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TOMOYO Linux Cross Reference
Linux/fs/ext4/inode.c

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  1 /*
  2  *  linux/fs/ext4/inode.c
  3  *
  4  * Copyright (C) 1992, 1993, 1994, 1995
  5  * Remy Card (card@masi.ibp.fr)
  6  * Laboratoire MASI - Institut Blaise Pascal
  7  * Universite Pierre et Marie Curie (Paris VI)
  8  *
  9  *  from
 10  *
 11  *  linux/fs/minix/inode.c
 12  *
 13  *  Copyright (C) 1991, 1992  Linus Torvalds
 14  *
 15  *  64-bit file support on 64-bit platforms by Jakub Jelinek
 16  *      (jj@sunsite.ms.mff.cuni.cz)
 17  *
 18  *  Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
 19  */
 20 
 21 #include <linux/fs.h>
 22 #include <linux/time.h>
 23 #include <linux/highuid.h>
 24 #include <linux/pagemap.h>
 25 #include <linux/dax.h>
 26 #include <linux/quotaops.h>
 27 #include <linux/string.h>
 28 #include <linux/buffer_head.h>
 29 #include <linux/writeback.h>
 30 #include <linux/pagevec.h>
 31 #include <linux/mpage.h>
 32 #include <linux/namei.h>
 33 #include <linux/uio.h>
 34 #include <linux/bio.h>
 35 #include <linux/workqueue.h>
 36 #include <linux/kernel.h>
 37 #include <linux/printk.h>
 38 #include <linux/slab.h>
 39 #include <linux/bitops.h>
 40 #include <linux/iomap.h>
 41 
 42 #include "ext4_jbd2.h"
 43 #include "xattr.h"
 44 #include "acl.h"
 45 #include "truncate.h"
 46 
 47 #include <trace/events/ext4.h>
 48 
 49 #define MPAGE_DA_EXTENT_TAIL 0x01
 50 
 51 static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw,
 52                               struct ext4_inode_info *ei)
 53 {
 54         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 55         __u32 csum;
 56         __u16 dummy_csum = 0;
 57         int offset = offsetof(struct ext4_inode, i_checksum_lo);
 58         unsigned int csum_size = sizeof(dummy_csum);
 59 
 60         csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)raw, offset);
 61         csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, csum_size);
 62         offset += csum_size;
 63         csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
 64                            EXT4_GOOD_OLD_INODE_SIZE - offset);
 65 
 66         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
 67                 offset = offsetof(struct ext4_inode, i_checksum_hi);
 68                 csum = ext4_chksum(sbi, csum, (__u8 *)raw +
 69                                    EXT4_GOOD_OLD_INODE_SIZE,
 70                                    offset - EXT4_GOOD_OLD_INODE_SIZE);
 71                 if (EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi)) {
 72                         csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum,
 73                                            csum_size);
 74                         offset += csum_size;
 75                 }
 76                 csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
 77                                    EXT4_INODE_SIZE(inode->i_sb) - offset);
 78         }
 79 
 80         return csum;
 81 }
 82 
 83 static int ext4_inode_csum_verify(struct inode *inode, struct ext4_inode *raw,
 84                                   struct ext4_inode_info *ei)
 85 {
 86         __u32 provided, calculated;
 87 
 88         if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
 89             cpu_to_le32(EXT4_OS_LINUX) ||
 90             !ext4_has_metadata_csum(inode->i_sb))
 91                 return 1;
 92 
 93         provided = le16_to_cpu(raw->i_checksum_lo);
 94         calculated = ext4_inode_csum(inode, raw, ei);
 95         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
 96             EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
 97                 provided |= ((__u32)le16_to_cpu(raw->i_checksum_hi)) << 16;
 98         else
 99                 calculated &= 0xFFFF;
100 
101         return provided == calculated;
102 }
103 
104 static void ext4_inode_csum_set(struct inode *inode, struct ext4_inode *raw,
105                                 struct ext4_inode_info *ei)
106 {
107         __u32 csum;
108 
109         if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
110             cpu_to_le32(EXT4_OS_LINUX) ||
111             !ext4_has_metadata_csum(inode->i_sb))
112                 return;
113 
114         csum = ext4_inode_csum(inode, raw, ei);
115         raw->i_checksum_lo = cpu_to_le16(csum & 0xFFFF);
116         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
117             EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
118                 raw->i_checksum_hi = cpu_to_le16(csum >> 16);
119 }
120 
121 static inline int ext4_begin_ordered_truncate(struct inode *inode,
122                                               loff_t new_size)
123 {
124         trace_ext4_begin_ordered_truncate(inode, new_size);
125         /*
126          * If jinode is zero, then we never opened the file for
127          * writing, so there's no need to call
128          * jbd2_journal_begin_ordered_truncate() since there's no
129          * outstanding writes we need to flush.
130          */
131         if (!EXT4_I(inode)->jinode)
132                 return 0;
133         return jbd2_journal_begin_ordered_truncate(EXT4_JOURNAL(inode),
134                                                    EXT4_I(inode)->jinode,
135                                                    new_size);
136 }
137 
138 static void ext4_invalidatepage(struct page *page, unsigned int offset,
139                                 unsigned int length);
140 static int __ext4_journalled_writepage(struct page *page, unsigned int len);
141 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh);
142 static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
143                                   int pextents);
144 
145 /*
146  * Test whether an inode is a fast symlink.
147  */
148 int ext4_inode_is_fast_symlink(struct inode *inode)
149 {
150         int ea_blocks = EXT4_I(inode)->i_file_acl ?
151                 EXT4_CLUSTER_SIZE(inode->i_sb) >> 9 : 0;
152 
153         if (ext4_has_inline_data(inode))
154                 return 0;
155 
156         return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
157 }
158 
159 /*
160  * Restart the transaction associated with *handle.  This does a commit,
161  * so before we call here everything must be consistently dirtied against
162  * this transaction.
163  */
164 int ext4_truncate_restart_trans(handle_t *handle, struct inode *inode,
165                                  int nblocks)
166 {
167         int ret;
168 
169         /*
170          * Drop i_data_sem to avoid deadlock with ext4_map_blocks.  At this
171          * moment, get_block can be called only for blocks inside i_size since
172          * page cache has been already dropped and writes are blocked by
173          * i_mutex. So we can safely drop the i_data_sem here.
174          */
175         BUG_ON(EXT4_JOURNAL(inode) == NULL);
176         jbd_debug(2, "restarting handle %p\n", handle);
177         up_write(&EXT4_I(inode)->i_data_sem);
178         ret = ext4_journal_restart(handle, nblocks);
179         down_write(&EXT4_I(inode)->i_data_sem);
180         ext4_discard_preallocations(inode);
181 
182         return ret;
183 }
184 
185 /*
186  * Called at the last iput() if i_nlink is zero.
187  */
188 void ext4_evict_inode(struct inode *inode)
189 {
190         handle_t *handle;
191         int err;
192 
193         trace_ext4_evict_inode(inode);
194 
195         if (inode->i_nlink) {
196                 /*
197                  * When journalling data dirty buffers are tracked only in the
198                  * journal. So although mm thinks everything is clean and
199                  * ready for reaping the inode might still have some pages to
200                  * write in the running transaction or waiting to be
201                  * checkpointed. Thus calling jbd2_journal_invalidatepage()
202                  * (via truncate_inode_pages()) to discard these buffers can
203                  * cause data loss. Also even if we did not discard these
204                  * buffers, we would have no way to find them after the inode
205                  * is reaped and thus user could see stale data if he tries to
206                  * read them before the transaction is checkpointed. So be
207                  * careful and force everything to disk here... We use
208                  * ei->i_datasync_tid to store the newest transaction
209                  * containing inode's data.
210                  *
211                  * Note that directories do not have this problem because they
212                  * don't use page cache.
213                  */
214                 if (inode->i_ino != EXT4_JOURNAL_INO &&
215                     ext4_should_journal_data(inode) &&
216                     (S_ISLNK(inode->i_mode) || S_ISREG(inode->i_mode))) {
217                         journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
218                         tid_t commit_tid = EXT4_I(inode)->i_datasync_tid;
219 
220                         jbd2_complete_transaction(journal, commit_tid);
221                         filemap_write_and_wait(&inode->i_data);
222                 }
223                 truncate_inode_pages_final(&inode->i_data);
224 
225                 goto no_delete;
226         }
227 
228         if (is_bad_inode(inode))
229                 goto no_delete;
230         dquot_initialize(inode);
231 
232         if (ext4_should_order_data(inode))
233                 ext4_begin_ordered_truncate(inode, 0);
234         truncate_inode_pages_final(&inode->i_data);
235 
236         /*
237          * Protect us against freezing - iput() caller didn't have to have any
238          * protection against it
239          */
240         sb_start_intwrite(inode->i_sb);
241         handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE,
242                                     ext4_blocks_for_truncate(inode)+3);
243         if (IS_ERR(handle)) {
244                 ext4_std_error(inode->i_sb, PTR_ERR(handle));
245                 /*
246                  * If we're going to skip the normal cleanup, we still need to
247                  * make sure that the in-core orphan linked list is properly
248                  * cleaned up.
249                  */
250                 ext4_orphan_del(NULL, inode);
251                 sb_end_intwrite(inode->i_sb);
252                 goto no_delete;
253         }
254 
255         if (IS_SYNC(inode))
256                 ext4_handle_sync(handle);
257         inode->i_size = 0;
258         err = ext4_mark_inode_dirty(handle, inode);
259         if (err) {
260                 ext4_warning(inode->i_sb,
261                              "couldn't mark inode dirty (err %d)", err);
262                 goto stop_handle;
263         }
264         if (inode->i_blocks) {
265                 err = ext4_truncate(inode);
266                 if (err) {
267                         ext4_error(inode->i_sb,
268                                    "couldn't truncate inode %lu (err %d)",
269                                    inode->i_ino, err);
270                         goto stop_handle;
271                 }
272         }
273 
274         /*
275          * ext4_ext_truncate() doesn't reserve any slop when it
276          * restarts journal transactions; therefore there may not be
277          * enough credits left in the handle to remove the inode from
278          * the orphan list and set the dtime field.
279          */
280         if (!ext4_handle_has_enough_credits(handle, 3)) {
281                 err = ext4_journal_extend(handle, 3);
282                 if (err > 0)
283                         err = ext4_journal_restart(handle, 3);
284                 if (err != 0) {
285                         ext4_warning(inode->i_sb,
286                                      "couldn't extend journal (err %d)", err);
287                 stop_handle:
288                         ext4_journal_stop(handle);
289                         ext4_orphan_del(NULL, inode);
290                         sb_end_intwrite(inode->i_sb);
291                         goto no_delete;
292                 }
293         }
294 
295         /*
296          * Kill off the orphan record which ext4_truncate created.
297          * AKPM: I think this can be inside the above `if'.
298          * Note that ext4_orphan_del() has to be able to cope with the
299          * deletion of a non-existent orphan - this is because we don't
300          * know if ext4_truncate() actually created an orphan record.
301          * (Well, we could do this if we need to, but heck - it works)
302          */
303         ext4_orphan_del(handle, inode);
304         EXT4_I(inode)->i_dtime  = get_seconds();
305 
306         /*
307          * One subtle ordering requirement: if anything has gone wrong
308          * (transaction abort, IO errors, whatever), then we can still
309          * do these next steps (the fs will already have been marked as
310          * having errors), but we can't free the inode if the mark_dirty
311          * fails.
312          */
313         if (ext4_mark_inode_dirty(handle, inode))
314                 /* If that failed, just do the required in-core inode clear. */
315                 ext4_clear_inode(inode);
316         else
317                 ext4_free_inode(handle, inode);
318         ext4_journal_stop(handle);
319         sb_end_intwrite(inode->i_sb);
320         return;
321 no_delete:
322         ext4_clear_inode(inode);        /* We must guarantee clearing of inode... */
323 }
324 
325 #ifdef CONFIG_QUOTA
326 qsize_t *ext4_get_reserved_space(struct inode *inode)
327 {
328         return &EXT4_I(inode)->i_reserved_quota;
329 }
330 #endif
331 
332 /*
333  * Called with i_data_sem down, which is important since we can call
334  * ext4_discard_preallocations() from here.
335  */
336 void ext4_da_update_reserve_space(struct inode *inode,
337                                         int used, int quota_claim)
338 {
339         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
340         struct ext4_inode_info *ei = EXT4_I(inode);
341 
342         spin_lock(&ei->i_block_reservation_lock);
343         trace_ext4_da_update_reserve_space(inode, used, quota_claim);
344         if (unlikely(used > ei->i_reserved_data_blocks)) {
345                 ext4_warning(inode->i_sb, "%s: ino %lu, used %d "
346                          "with only %d reserved data blocks",
347                          __func__, inode->i_ino, used,
348                          ei->i_reserved_data_blocks);
349                 WARN_ON(1);
350                 used = ei->i_reserved_data_blocks;
351         }
352 
353         /* Update per-inode reservations */
354         ei->i_reserved_data_blocks -= used;
355         percpu_counter_sub(&sbi->s_dirtyclusters_counter, used);
356 
357         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
358 
359         /* Update quota subsystem for data blocks */
360         if (quota_claim)
361                 dquot_claim_block(inode, EXT4_C2B(sbi, used));
362         else {
363                 /*
364                  * We did fallocate with an offset that is already delayed
365                  * allocated. So on delayed allocated writeback we should
366                  * not re-claim the quota for fallocated blocks.
367                  */
368                 dquot_release_reservation_block(inode, EXT4_C2B(sbi, used));
369         }
370 
371         /*
372          * If we have done all the pending block allocations and if
373          * there aren't any writers on the inode, we can discard the
374          * inode's preallocations.
375          */
376         if ((ei->i_reserved_data_blocks == 0) &&
377             (atomic_read(&inode->i_writecount) == 0))
378                 ext4_discard_preallocations(inode);
379 }
380 
381 static int __check_block_validity(struct inode *inode, const char *func,
382                                 unsigned int line,
383                                 struct ext4_map_blocks *map)
384 {
385         if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), map->m_pblk,
386                                    map->m_len)) {
387                 ext4_error_inode(inode, func, line, map->m_pblk,
388                                  "lblock %lu mapped to illegal pblock "
389                                  "(length %d)", (unsigned long) map->m_lblk,
390                                  map->m_len);
391                 return -EFSCORRUPTED;
392         }
393         return 0;
394 }
395 
396 int ext4_issue_zeroout(struct inode *inode, ext4_lblk_t lblk, ext4_fsblk_t pblk,
397                        ext4_lblk_t len)
398 {
399         int ret;
400 
401         if (ext4_encrypted_inode(inode))
402                 return fscrypt_zeroout_range(inode, lblk, pblk, len);
403 
404         ret = sb_issue_zeroout(inode->i_sb, pblk, len, GFP_NOFS);
405         if (ret > 0)
406                 ret = 0;
407 
408         return ret;
409 }
410 
411 #define check_block_validity(inode, map)        \
412         __check_block_validity((inode), __func__, __LINE__, (map))
413 
414 #ifdef ES_AGGRESSIVE_TEST
415 static void ext4_map_blocks_es_recheck(handle_t *handle,
416                                        struct inode *inode,
417                                        struct ext4_map_blocks *es_map,
418                                        struct ext4_map_blocks *map,
419                                        int flags)
420 {
421         int retval;
422 
423         map->m_flags = 0;
424         /*
425          * There is a race window that the result is not the same.
426          * e.g. xfstests #223 when dioread_nolock enables.  The reason
427          * is that we lookup a block mapping in extent status tree with
428          * out taking i_data_sem.  So at the time the unwritten extent
429          * could be converted.
430          */
431         down_read(&EXT4_I(inode)->i_data_sem);
432         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
433                 retval = ext4_ext_map_blocks(handle, inode, map, flags &
434                                              EXT4_GET_BLOCKS_KEEP_SIZE);
435         } else {
436                 retval = ext4_ind_map_blocks(handle, inode, map, flags &
437                                              EXT4_GET_BLOCKS_KEEP_SIZE);
438         }
439         up_read((&EXT4_I(inode)->i_data_sem));
440 
441         /*
442          * We don't check m_len because extent will be collpased in status
443          * tree.  So the m_len might not equal.
444          */
445         if (es_map->m_lblk != map->m_lblk ||
446             es_map->m_flags != map->m_flags ||
447             es_map->m_pblk != map->m_pblk) {
448                 printk("ES cache assertion failed for inode: %lu "
449                        "es_cached ex [%d/%d/%llu/%x] != "
450                        "found ex [%d/%d/%llu/%x] retval %d flags %x\n",
451                        inode->i_ino, es_map->m_lblk, es_map->m_len,
452                        es_map->m_pblk, es_map->m_flags, map->m_lblk,
453                        map->m_len, map->m_pblk, map->m_flags,
454                        retval, flags);
455         }
456 }
457 #endif /* ES_AGGRESSIVE_TEST */
458 
459 /*
460  * The ext4_map_blocks() function tries to look up the requested blocks,
461  * and returns if the blocks are already mapped.
462  *
463  * Otherwise it takes the write lock of the i_data_sem and allocate blocks
464  * and store the allocated blocks in the result buffer head and mark it
465  * mapped.
466  *
467  * If file type is extents based, it will call ext4_ext_map_blocks(),
468  * Otherwise, call with ext4_ind_map_blocks() to handle indirect mapping
469  * based files
470  *
471  * On success, it returns the number of blocks being mapped or allocated.  if
472  * create==0 and the blocks are pre-allocated and unwritten, the resulting @map
473  * is marked as unwritten. If the create == 1, it will mark @map as mapped.
474  *
475  * It returns 0 if plain look up failed (blocks have not been allocated), in
476  * that case, @map is returned as unmapped but we still do fill map->m_len to
477  * indicate the length of a hole starting at map->m_lblk.
478  *
479  * It returns the error in case of allocation failure.
480  */
481 int ext4_map_blocks(handle_t *handle, struct inode *inode,
482                     struct ext4_map_blocks *map, int flags)
483 {
484         struct extent_status es;
485         int retval;
486         int ret = 0;
487 #ifdef ES_AGGRESSIVE_TEST
488         struct ext4_map_blocks orig_map;
489 
490         memcpy(&orig_map, map, sizeof(*map));
491 #endif
492 
493         map->m_flags = 0;
494         ext_debug("ext4_map_blocks(): inode %lu, flag %d, max_blocks %u,"
495                   "logical block %lu\n", inode->i_ino, flags, map->m_len,
496                   (unsigned long) map->m_lblk);
497 
498         /*
499          * ext4_map_blocks returns an int, and m_len is an unsigned int
500          */
501         if (unlikely(map->m_len > INT_MAX))
502                 map->m_len = INT_MAX;
503 
504         /* We can handle the block number less than EXT_MAX_BLOCKS */
505         if (unlikely(map->m_lblk >= EXT_MAX_BLOCKS))
506                 return -EFSCORRUPTED;
507 
508         /* Lookup extent status tree firstly */
509         if (ext4_es_lookup_extent(inode, map->m_lblk, &es)) {
510                 if (ext4_es_is_written(&es) || ext4_es_is_unwritten(&es)) {
511                         map->m_pblk = ext4_es_pblock(&es) +
512                                         map->m_lblk - es.es_lblk;
513                         map->m_flags |= ext4_es_is_written(&es) ?
514                                         EXT4_MAP_MAPPED : EXT4_MAP_UNWRITTEN;
515                         retval = es.es_len - (map->m_lblk - es.es_lblk);
516                         if (retval > map->m_len)
517                                 retval = map->m_len;
518                         map->m_len = retval;
519                 } else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) {
520                         map->m_pblk = 0;
521                         retval = es.es_len - (map->m_lblk - es.es_lblk);
522                         if (retval > map->m_len)
523                                 retval = map->m_len;
524                         map->m_len = retval;
525                         retval = 0;
526                 } else {
527                         BUG_ON(1);
528                 }
529 #ifdef ES_AGGRESSIVE_TEST
530                 ext4_map_blocks_es_recheck(handle, inode, map,
531                                            &orig_map, flags);
532 #endif
533                 goto found;
534         }
535 
536         /*
537          * Try to see if we can get the block without requesting a new
538          * file system block.
539          */
540         down_read(&EXT4_I(inode)->i_data_sem);
541         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
542                 retval = ext4_ext_map_blocks(handle, inode, map, flags &
543                                              EXT4_GET_BLOCKS_KEEP_SIZE);
544         } else {
545                 retval = ext4_ind_map_blocks(handle, inode, map, flags &
546                                              EXT4_GET_BLOCKS_KEEP_SIZE);
547         }
548         if (retval > 0) {
549                 unsigned int status;
550 
551                 if (unlikely(retval != map->m_len)) {
552                         ext4_warning(inode->i_sb,
553                                      "ES len assertion failed for inode "
554                                      "%lu: retval %d != map->m_len %d",
555                                      inode->i_ino, retval, map->m_len);
556                         WARN_ON(1);
557                 }
558 
559                 status = map->m_flags & EXT4_MAP_UNWRITTEN ?
560                                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
561                 if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
562                     !(status & EXTENT_STATUS_WRITTEN) &&
563                     ext4_find_delalloc_range(inode, map->m_lblk,
564                                              map->m_lblk + map->m_len - 1))
565                         status |= EXTENT_STATUS_DELAYED;
566                 ret = ext4_es_insert_extent(inode, map->m_lblk,
567                                             map->m_len, map->m_pblk, status);
568                 if (ret < 0)
569                         retval = ret;
570         }
571         up_read((&EXT4_I(inode)->i_data_sem));
572 
573 found:
574         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
575                 ret = check_block_validity(inode, map);
576                 if (ret != 0)
577                         return ret;
578         }
579 
580         /* If it is only a block(s) look up */
581         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
582                 return retval;
583 
584         /*
585          * Returns if the blocks have already allocated
586          *
587          * Note that if blocks have been preallocated
588          * ext4_ext_get_block() returns the create = 0
589          * with buffer head unmapped.
590          */
591         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED)
592                 /*
593                  * If we need to convert extent to unwritten
594                  * we continue and do the actual work in
595                  * ext4_ext_map_blocks()
596                  */
597                 if (!(flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN))
598                         return retval;
599 
600         /*
601          * Here we clear m_flags because after allocating an new extent,
602          * it will be set again.
603          */
604         map->m_flags &= ~EXT4_MAP_FLAGS;
605 
606         /*
607          * New blocks allocate and/or writing to unwritten extent
608          * will possibly result in updating i_data, so we take
609          * the write lock of i_data_sem, and call get_block()
610          * with create == 1 flag.
611          */
612         down_write(&EXT4_I(inode)->i_data_sem);
613 
614         /*
615          * We need to check for EXT4 here because migrate
616          * could have changed the inode type in between
617          */
618         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
619                 retval = ext4_ext_map_blocks(handle, inode, map, flags);
620         } else {
621                 retval = ext4_ind_map_blocks(handle, inode, map, flags);
622 
623                 if (retval > 0 && map->m_flags & EXT4_MAP_NEW) {
624                         /*
625                          * We allocated new blocks which will result in
626                          * i_data's format changing.  Force the migrate
627                          * to fail by clearing migrate flags
628                          */
629                         ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
630                 }
631 
632                 /*
633                  * Update reserved blocks/metadata blocks after successful
634                  * block allocation which had been deferred till now. We don't
635                  * support fallocate for non extent files. So we can update
636                  * reserve space here.
637                  */
638                 if ((retval > 0) &&
639                         (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE))
640                         ext4_da_update_reserve_space(inode, retval, 1);
641         }
642 
643         if (retval > 0) {
644                 unsigned int status;
645 
646                 if (unlikely(retval != map->m_len)) {
647                         ext4_warning(inode->i_sb,
648                                      "ES len assertion failed for inode "
649                                      "%lu: retval %d != map->m_len %d",
650                                      inode->i_ino, retval, map->m_len);
651                         WARN_ON(1);
652                 }
653 
654                 /*
655                  * We have to zeroout blocks before inserting them into extent
656                  * status tree. Otherwise someone could look them up there and
657                  * use them before they are really zeroed. We also have to
658                  * unmap metadata before zeroing as otherwise writeback can
659                  * overwrite zeros with stale data from block device.
660                  */
661                 if (flags & EXT4_GET_BLOCKS_ZERO &&
662                     map->m_flags & EXT4_MAP_MAPPED &&
663                     map->m_flags & EXT4_MAP_NEW) {
664                         clean_bdev_aliases(inode->i_sb->s_bdev, map->m_pblk,
665                                            map->m_len);
666                         ret = ext4_issue_zeroout(inode, map->m_lblk,
667                                                  map->m_pblk, map->m_len);
668                         if (ret) {
669                                 retval = ret;
670                                 goto out_sem;
671                         }
672                 }
673 
674                 /*
675                  * If the extent has been zeroed out, we don't need to update
676                  * extent status tree.
677                  */
678                 if ((flags & EXT4_GET_BLOCKS_PRE_IO) &&
679                     ext4_es_lookup_extent(inode, map->m_lblk, &es)) {
680                         if (ext4_es_is_written(&es))
681                                 goto out_sem;
682                 }
683                 status = map->m_flags & EXT4_MAP_UNWRITTEN ?
684                                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
685                 if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
686                     !(status & EXTENT_STATUS_WRITTEN) &&
687                     ext4_find_delalloc_range(inode, map->m_lblk,
688                                              map->m_lblk + map->m_len - 1))
689                         status |= EXTENT_STATUS_DELAYED;
690                 ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
691                                             map->m_pblk, status);
692                 if (ret < 0) {
693                         retval = ret;
694                         goto out_sem;
695                 }
696         }
697 
698 out_sem:
699         up_write((&EXT4_I(inode)->i_data_sem));
700         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
701                 ret = check_block_validity(inode, map);
702                 if (ret != 0)
703                         return ret;
704 
705                 /*
706                  * Inodes with freshly allocated blocks where contents will be
707                  * visible after transaction commit must be on transaction's
708                  * ordered data list.
709                  */
710                 if (map->m_flags & EXT4_MAP_NEW &&
711                     !(map->m_flags & EXT4_MAP_UNWRITTEN) &&
712                     !(flags & EXT4_GET_BLOCKS_ZERO) &&
713                     !IS_NOQUOTA(inode) &&
714                     ext4_should_order_data(inode)) {
715                         if (flags & EXT4_GET_BLOCKS_IO_SUBMIT)
716                                 ret = ext4_jbd2_inode_add_wait(handle, inode);
717                         else
718                                 ret = ext4_jbd2_inode_add_write(handle, inode);
719                         if (ret)
720                                 return ret;
721                 }
722         }
723         return retval;
724 }
725 
726 /*
727  * Update EXT4_MAP_FLAGS in bh->b_state. For buffer heads attached to pages
728  * we have to be careful as someone else may be manipulating b_state as well.
729  */
730 static void ext4_update_bh_state(struct buffer_head *bh, unsigned long flags)
731 {
732         unsigned long old_state;
733         unsigned long new_state;
734 
735         flags &= EXT4_MAP_FLAGS;
736 
737         /* Dummy buffer_head? Set non-atomically. */
738         if (!bh->b_page) {
739                 bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | flags;
740                 return;
741         }
742         /*
743          * Someone else may be modifying b_state. Be careful! This is ugly but
744          * once we get rid of using bh as a container for mapping information
745          * to pass to / from get_block functions, this can go away.
746          */
747         do {
748                 old_state = READ_ONCE(bh->b_state);
749                 new_state = (old_state & ~EXT4_MAP_FLAGS) | flags;
750         } while (unlikely(
751                  cmpxchg(&bh->b_state, old_state, new_state) != old_state));
752 }
753 
754 static int _ext4_get_block(struct inode *inode, sector_t iblock,
755                            struct buffer_head *bh, int flags)
756 {
757         struct ext4_map_blocks map;
758         int ret = 0;
759 
760         if (ext4_has_inline_data(inode))
761                 return -ERANGE;
762 
763         map.m_lblk = iblock;
764         map.m_len = bh->b_size >> inode->i_blkbits;
765 
766         ret = ext4_map_blocks(ext4_journal_current_handle(), inode, &map,
767                               flags);
768         if (ret > 0) {
769                 map_bh(bh, inode->i_sb, map.m_pblk);
770                 ext4_update_bh_state(bh, map.m_flags);
771                 bh->b_size = inode->i_sb->s_blocksize * map.m_len;
772                 ret = 0;
773         } else if (ret == 0) {
774                 /* hole case, need to fill in bh->b_size */
775                 bh->b_size = inode->i_sb->s_blocksize * map.m_len;
776         }
777         return ret;
778 }
779 
780 int ext4_get_block(struct inode *inode, sector_t iblock,
781                    struct buffer_head *bh, int create)
782 {
783         return _ext4_get_block(inode, iblock, bh,
784                                create ? EXT4_GET_BLOCKS_CREATE : 0);
785 }
786 
787 /*
788  * Get block function used when preparing for buffered write if we require
789  * creating an unwritten extent if blocks haven't been allocated.  The extent
790  * will be converted to written after the IO is complete.
791  */
792 int ext4_get_block_unwritten(struct inode *inode, sector_t iblock,
793                              struct buffer_head *bh_result, int create)
794 {
795         ext4_debug("ext4_get_block_unwritten: inode %lu, create flag %d\n",
796                    inode->i_ino, create);
797         return _ext4_get_block(inode, iblock, bh_result,
798                                EXT4_GET_BLOCKS_IO_CREATE_EXT);
799 }
800 
801 /* Maximum number of blocks we map for direct IO at once. */
802 #define DIO_MAX_BLOCKS 4096
803 
804 /*
805  * Get blocks function for the cases that need to start a transaction -
806  * generally difference cases of direct IO and DAX IO. It also handles retries
807  * in case of ENOSPC.
808  */
809 static int ext4_get_block_trans(struct inode *inode, sector_t iblock,
810                                 struct buffer_head *bh_result, int flags)
811 {
812         int dio_credits;
813         handle_t *handle;
814         int retries = 0;
815         int ret;
816 
817         /* Trim mapping request to maximum we can map at once for DIO */
818         if (bh_result->b_size >> inode->i_blkbits > DIO_MAX_BLOCKS)
819                 bh_result->b_size = DIO_MAX_BLOCKS << inode->i_blkbits;
820         dio_credits = ext4_chunk_trans_blocks(inode,
821                                       bh_result->b_size >> inode->i_blkbits);
822 retry:
823         handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, dio_credits);
824         if (IS_ERR(handle))
825                 return PTR_ERR(handle);
826 
827         ret = _ext4_get_block(inode, iblock, bh_result, flags);
828         ext4_journal_stop(handle);
829 
830         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
831                 goto retry;
832         return ret;
833 }
834 
835 /* Get block function for DIO reads and writes to inodes without extents */
836 int ext4_dio_get_block(struct inode *inode, sector_t iblock,
837                        struct buffer_head *bh, int create)
838 {
839         /* We don't expect handle for direct IO */
840         WARN_ON_ONCE(ext4_journal_current_handle());
841 
842         if (!create)
843                 return _ext4_get_block(inode, iblock, bh, 0);
844         return ext4_get_block_trans(inode, iblock, bh, EXT4_GET_BLOCKS_CREATE);
845 }
846 
847 /*
848  * Get block function for AIO DIO writes when we create unwritten extent if
849  * blocks are not allocated yet. The extent will be converted to written
850  * after IO is complete.
851  */
852 static int ext4_dio_get_block_unwritten_async(struct inode *inode,
853                 sector_t iblock, struct buffer_head *bh_result, int create)
854 {
855         int ret;
856 
857         /* We don't expect handle for direct IO */
858         WARN_ON_ONCE(ext4_journal_current_handle());
859 
860         ret = ext4_get_block_trans(inode, iblock, bh_result,
861                                    EXT4_GET_BLOCKS_IO_CREATE_EXT);
862 
863         /*
864          * When doing DIO using unwritten extents, we need io_end to convert
865          * unwritten extents to written on IO completion. We allocate io_end
866          * once we spot unwritten extent and store it in b_private. Generic
867          * DIO code keeps b_private set and furthermore passes the value to
868          * our completion callback in 'private' argument.
869          */
870         if (!ret && buffer_unwritten(bh_result)) {
871                 if (!bh_result->b_private) {
872                         ext4_io_end_t *io_end;
873 
874                         io_end = ext4_init_io_end(inode, GFP_KERNEL);
875                         if (!io_end)
876                                 return -ENOMEM;
877                         bh_result->b_private = io_end;
878                         ext4_set_io_unwritten_flag(inode, io_end);
879                 }
880                 set_buffer_defer_completion(bh_result);
881         }
882 
883         return ret;
884 }
885 
886 /*
887  * Get block function for non-AIO DIO writes when we create unwritten extent if
888  * blocks are not allocated yet. The extent will be converted to written
889  * after IO is complete from ext4_ext_direct_IO() function.
890  */
891 static int ext4_dio_get_block_unwritten_sync(struct inode *inode,
892                 sector_t iblock, struct buffer_head *bh_result, int create)
893 {
894         int ret;
895 
896         /* We don't expect handle for direct IO */
897         WARN_ON_ONCE(ext4_journal_current_handle());
898 
899         ret = ext4_get_block_trans(inode, iblock, bh_result,
900                                    EXT4_GET_BLOCKS_IO_CREATE_EXT);
901 
902         /*
903          * Mark inode as having pending DIO writes to unwritten extents.
904          * ext4_ext_direct_IO() checks this flag and converts extents to
905          * written.
906          */
907         if (!ret && buffer_unwritten(bh_result))
908                 ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
909 
910         return ret;
911 }
912 
913 static int ext4_dio_get_block_overwrite(struct inode *inode, sector_t iblock,
914                    struct buffer_head *bh_result, int create)
915 {
916         int ret;
917 
918         ext4_debug("ext4_dio_get_block_overwrite: inode %lu, create flag %d\n",
919                    inode->i_ino, create);
920         /* We don't expect handle for direct IO */
921         WARN_ON_ONCE(ext4_journal_current_handle());
922 
923         ret = _ext4_get_block(inode, iblock, bh_result, 0);
924         /*
925          * Blocks should have been preallocated! ext4_file_write_iter() checks
926          * that.
927          */
928         WARN_ON_ONCE(!buffer_mapped(bh_result) || buffer_unwritten(bh_result));
929 
930         return ret;
931 }
932 
933 
934 /*
935  * `handle' can be NULL if create is zero
936  */
937 struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
938                                 ext4_lblk_t block, int map_flags)
939 {
940         struct ext4_map_blocks map;
941         struct buffer_head *bh;
942         int create = map_flags & EXT4_GET_BLOCKS_CREATE;
943         int err;
944 
945         J_ASSERT(handle != NULL || create == 0);
946 
947         map.m_lblk = block;
948         map.m_len = 1;
949         err = ext4_map_blocks(handle, inode, &map, map_flags);
950 
951         if (err == 0)
952                 return create ? ERR_PTR(-ENOSPC) : NULL;
953         if (err < 0)
954                 return ERR_PTR(err);
955 
956         bh = sb_getblk(inode->i_sb, map.m_pblk);
957         if (unlikely(!bh))
958                 return ERR_PTR(-ENOMEM);
959         if (map.m_flags & EXT4_MAP_NEW) {
960                 J_ASSERT(create != 0);
961                 J_ASSERT(handle != NULL);
962 
963                 /*
964                  * Now that we do not always journal data, we should
965                  * keep in mind whether this should always journal the
966                  * new buffer as metadata.  For now, regular file
967                  * writes use ext4_get_block instead, so it's not a
968                  * problem.
969                  */
970                 lock_buffer(bh);
971                 BUFFER_TRACE(bh, "call get_create_access");
972                 err = ext4_journal_get_create_access(handle, bh);
973                 if (unlikely(err)) {
974                         unlock_buffer(bh);
975                         goto errout;
976                 }
977                 if (!buffer_uptodate(bh)) {
978                         memset(bh->b_data, 0, inode->i_sb->s_blocksize);
979                         set_buffer_uptodate(bh);
980                 }
981                 unlock_buffer(bh);
982                 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
983                 err = ext4_handle_dirty_metadata(handle, inode, bh);
984                 if (unlikely(err))
985                         goto errout;
986         } else
987                 BUFFER_TRACE(bh, "not a new buffer");
988         return bh;
989 errout:
990         brelse(bh);
991         return ERR_PTR(err);
992 }
993 
994 struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
995                                ext4_lblk_t block, int map_flags)
996 {
997         struct buffer_head *bh;
998 
999         bh = ext4_getblk(handle, inode, block, map_flags);
1000         if (IS_ERR(bh))
1001                 return bh;
1002         if (!bh || buffer_uptodate(bh))
1003                 return bh;
1004         ll_rw_block(REQ_OP_READ, REQ_META | REQ_PRIO, 1, &bh);
1005         wait_on_buffer(bh);
1006         if (buffer_uptodate(bh))
1007                 return bh;
1008         put_bh(bh);
1009         return ERR_PTR(-EIO);
1010 }
1011 
1012 int ext4_walk_page_buffers(handle_t *handle,
1013                            struct buffer_head *head,
1014                            unsigned from,
1015                            unsigned to,
1016                            int *partial,
1017                            int (*fn)(handle_t *handle,
1018                                      struct buffer_head *bh))
1019 {
1020         struct buffer_head *bh;
1021         unsigned block_start, block_end;
1022         unsigned blocksize = head->b_size;
1023         int err, ret = 0;
1024         struct buffer_head *next;
1025 
1026         for (bh = head, block_start = 0;
1027              ret == 0 && (bh != head || !block_start);
1028              block_start = block_end, bh = next) {
1029                 next = bh->b_this_page;
1030                 block_end = block_start + blocksize;
1031                 if (block_end <= from || block_start >= to) {
1032                         if (partial && !buffer_uptodate(bh))
1033                                 *partial = 1;
1034                         continue;
1035                 }
1036                 err = (*fn)(handle, bh);
1037                 if (!ret)
1038                         ret = err;
1039         }
1040         return ret;
1041 }
1042 
1043 /*
1044  * To preserve ordering, it is essential that the hole instantiation and
1045  * the data write be encapsulated in a single transaction.  We cannot
1046  * close off a transaction and start a new one between the ext4_get_block()
1047  * and the commit_write().  So doing the jbd2_journal_start at the start of
1048  * prepare_write() is the right place.
1049  *
1050  * Also, this function can nest inside ext4_writepage().  In that case, we
1051  * *know* that ext4_writepage() has generated enough buffer credits to do the
1052  * whole page.  So we won't block on the journal in that case, which is good,
1053  * because the caller may be PF_MEMALLOC.
1054  *
1055  * By accident, ext4 can be reentered when a transaction is open via
1056  * quota file writes.  If we were to commit the transaction while thus
1057  * reentered, there can be a deadlock - we would be holding a quota
1058  * lock, and the commit would never complete if another thread had a
1059  * transaction open and was blocking on the quota lock - a ranking
1060  * violation.
1061  *
1062  * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
1063  * will _not_ run commit under these circumstances because handle->h_ref
1064  * is elevated.  We'll still have enough credits for the tiny quotafile
1065  * write.
1066  */
1067 int do_journal_get_write_access(handle_t *handle,
1068                                 struct buffer_head *bh)
1069 {
1070         int dirty = buffer_dirty(bh);
1071         int ret;
1072 
1073         if (!buffer_mapped(bh) || buffer_freed(bh))
1074                 return 0;
1075         /*
1076          * __block_write_begin() could have dirtied some buffers. Clean
1077          * the dirty bit as jbd2_journal_get_write_access() could complain
1078          * otherwise about fs integrity issues. Setting of the dirty bit
1079          * by __block_write_begin() isn't a real problem here as we clear
1080          * the bit before releasing a page lock and thus writeback cannot
1081          * ever write the buffer.
1082          */
1083         if (dirty)
1084                 clear_buffer_dirty(bh);
1085         BUFFER_TRACE(bh, "get write access");
1086         ret = ext4_journal_get_write_access(handle, bh);
1087         if (!ret && dirty)
1088                 ret = ext4_handle_dirty_metadata(handle, NULL, bh);
1089         return ret;
1090 }
1091 
1092 #ifdef CONFIG_EXT4_FS_ENCRYPTION
1093 static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
1094                                   get_block_t *get_block)
1095 {
1096         unsigned from = pos & (PAGE_SIZE - 1);
1097         unsigned to = from + len;
1098         struct inode *inode = page->mapping->host;
1099         unsigned block_start, block_end;
1100         sector_t block;
1101         int err = 0;
1102         unsigned blocksize = inode->i_sb->s_blocksize;
1103         unsigned bbits;
1104         struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
1105         bool decrypt = false;
1106 
1107         BUG_ON(!PageLocked(page));
1108         BUG_ON(from > PAGE_SIZE);
1109         BUG_ON(to > PAGE_SIZE);
1110         BUG_ON(from > to);
1111 
1112         if (!page_has_buffers(page))
1113                 create_empty_buffers(page, blocksize, 0);
1114         head = page_buffers(page);
1115         bbits = ilog2(blocksize);
1116         block = (sector_t)page->index << (PAGE_SHIFT - bbits);
1117 
1118         for (bh = head, block_start = 0; bh != head || !block_start;
1119             block++, block_start = block_end, bh = bh->b_this_page) {
1120                 block_end = block_start + blocksize;
1121                 if (block_end <= from || block_start >= to) {
1122                         if (PageUptodate(page)) {
1123                                 if (!buffer_uptodate(bh))
1124                                         set_buffer_uptodate(bh);
1125                         }
1126                         continue;
1127                 }
1128                 if (buffer_new(bh))
1129                         clear_buffer_new(bh);
1130                 if (!buffer_mapped(bh)) {
1131                         WARN_ON(bh->b_size != blocksize);
1132                         err = get_block(inode, block, bh, 1);
1133                         if (err)
1134                                 break;
1135                         if (buffer_new(bh)) {
1136                                 clean_bdev_bh_alias(bh);
1137                                 if (PageUptodate(page)) {
1138                                         clear_buffer_new(bh);
1139                                         set_buffer_uptodate(bh);
1140                                         mark_buffer_dirty(bh);
1141                                         continue;
1142                                 }
1143                                 if (block_end > to || block_start < from)
1144                                         zero_user_segments(page, to, block_end,
1145                                                            block_start, from);
1146                                 continue;
1147                         }
1148                 }
1149                 if (PageUptodate(page)) {
1150                         if (!buffer_uptodate(bh))
1151                                 set_buffer_uptodate(bh);
1152                         continue;
1153                 }
1154                 if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
1155                     !buffer_unwritten(bh) &&
1156                     (block_start < from || block_end > to)) {
1157                         ll_rw_block(REQ_OP_READ, 0, 1, &bh);
1158                         *wait_bh++ = bh;
1159                         decrypt = ext4_encrypted_inode(inode) &&
1160                                 S_ISREG(inode->i_mode);
1161                 }
1162         }
1163         /*
1164          * If we issued read requests, let them complete.
1165          */
1166         while (wait_bh > wait) {
1167                 wait_on_buffer(*--wait_bh);
1168                 if (!buffer_uptodate(*wait_bh))
1169                         err = -EIO;
1170         }
1171         if (unlikely(err))
1172                 page_zero_new_buffers(page, from, to);
1173         else if (decrypt)
1174                 err = fscrypt_decrypt_page(page->mapping->host, page,
1175                                 PAGE_SIZE, 0, page->index);
1176         return err;
1177 }
1178 #endif
1179 
1180 static int ext4_write_begin(struct file *file, struct address_space *mapping,
1181                             loff_t pos, unsigned len, unsigned flags,
1182                             struct page **pagep, void **fsdata)
1183 {
1184         struct inode *inode = mapping->host;
1185         int ret, needed_blocks;
1186         handle_t *handle;
1187         int retries = 0;
1188         struct page *page;
1189         pgoff_t index;
1190         unsigned from, to;
1191 
1192         trace_ext4_write_begin(inode, pos, len, flags);
1193         /*
1194          * Reserve one block more for addition to orphan list in case
1195          * we allocate blocks but write fails for some reason
1196          */
1197         needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
1198         index = pos >> PAGE_SHIFT;
1199         from = pos & (PAGE_SIZE - 1);
1200         to = from + len;
1201 
1202         if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
1203                 ret = ext4_try_to_write_inline_data(mapping, inode, pos, len,
1204                                                     flags, pagep);
1205                 if (ret < 0)
1206                         return ret;
1207                 if (ret == 1)
1208                         return 0;
1209         }
1210 
1211         /*
1212          * grab_cache_page_write_begin() can take a long time if the
1213          * system is thrashing due to memory pressure, or if the page
1214          * is being written back.  So grab it first before we start
1215          * the transaction handle.  This also allows us to allocate
1216          * the page (if needed) without using GFP_NOFS.
1217          */
1218 retry_grab:
1219         page = grab_cache_page_write_begin(mapping, index, flags);
1220         if (!page)
1221                 return -ENOMEM;
1222         unlock_page(page);
1223 
1224 retry_journal:
1225         handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, needed_blocks);
1226         if (IS_ERR(handle)) {
1227                 put_page(page);
1228                 return PTR_ERR(handle);
1229         }
1230 
1231         lock_page(page);
1232         if (page->mapping != mapping) {
1233                 /* The page got truncated from under us */
1234                 unlock_page(page);
1235                 put_page(page);
1236                 ext4_journal_stop(handle);
1237                 goto retry_grab;
1238         }
1239         /* In case writeback began while the page was unlocked */
1240         wait_for_stable_page(page);
1241 
1242 #ifdef CONFIG_EXT4_FS_ENCRYPTION
1243         if (ext4_should_dioread_nolock(inode))
1244                 ret = ext4_block_write_begin(page, pos, len,
1245                                              ext4_get_block_unwritten);
1246         else
1247                 ret = ext4_block_write_begin(page, pos, len,
1248                                              ext4_get_block);
1249 #else
1250         if (ext4_should_dioread_nolock(inode))
1251                 ret = __block_write_begin(page, pos, len,
1252                                           ext4_get_block_unwritten);
1253         else
1254                 ret = __block_write_begin(page, pos, len, ext4_get_block);
1255 #endif
1256         if (!ret && ext4_should_journal_data(inode)) {
1257                 ret = ext4_walk_page_buffers(handle, page_buffers(page),
1258                                              from, to, NULL,
1259                                              do_journal_get_write_access);
1260         }
1261 
1262         if (ret) {
1263                 unlock_page(page);
1264                 /*
1265                  * __block_write_begin may have instantiated a few blocks
1266                  * outside i_size.  Trim these off again. Don't need
1267                  * i_size_read because we hold i_mutex.
1268                  *
1269                  * Add inode to orphan list in case we crash before
1270                  * truncate finishes
1271                  */
1272                 if (pos + len > inode->i_size && ext4_can_truncate(inode))
1273                         ext4_orphan_add(handle, inode);
1274 
1275                 ext4_journal_stop(handle);
1276                 if (pos + len > inode->i_size) {
1277                         ext4_truncate_failed_write(inode);
1278                         /*
1279                          * If truncate failed early the inode might
1280                          * still be on the orphan list; we need to
1281                          * make sure the inode is removed from the
1282                          * orphan list in that case.
1283                          */
1284                         if (inode->i_nlink)
1285                                 ext4_orphan_del(NULL, inode);
1286                 }
1287 
1288                 if (ret == -ENOSPC &&
1289                     ext4_should_retry_alloc(inode->i_sb, &retries))
1290                         goto retry_journal;
1291                 put_page(page);
1292                 return ret;
1293         }
1294         *pagep = page;
1295         return ret;
1296 }
1297 
1298 /* For write_end() in data=journal mode */
1299 static int write_end_fn(handle_t *handle, struct buffer_head *bh)
1300 {
1301         int ret;
1302         if (!buffer_mapped(bh) || buffer_freed(bh))
1303                 return 0;
1304         set_buffer_uptodate(bh);
1305         ret = ext4_handle_dirty_metadata(handle, NULL, bh);
1306         clear_buffer_meta(bh);
1307         clear_buffer_prio(bh);
1308         return ret;
1309 }
1310 
1311 /*
1312  * We need to pick up the new inode size which generic_commit_write gave us
1313  * `file' can be NULL - eg, when called from page_symlink().
1314  *
1315  * ext4 never places buffers on inode->i_mapping->private_list.  metadata
1316  * buffers are managed internally.
1317  */
1318 static int ext4_write_end(struct file *file,
1319                           struct address_space *mapping,
1320                           loff_t pos, unsigned len, unsigned copied,
1321                           struct page *page, void *fsdata)
1322 {
1323         handle_t *handle = ext4_journal_current_handle();
1324         struct inode *inode = mapping->host;
1325         loff_t old_size = inode->i_size;
1326         int ret = 0, ret2;
1327         int i_size_changed = 0;
1328 
1329         trace_ext4_write_end(inode, pos, len, copied);
1330         if (ext4_has_inline_data(inode)) {
1331                 ret = ext4_write_inline_data_end(inode, pos, len,
1332                                                  copied, page);
1333                 if (ret < 0) {
1334                         unlock_page(page);
1335                         put_page(page);
1336                         goto errout;
1337                 }
1338                 copied = ret;
1339         } else
1340                 copied = block_write_end(file, mapping, pos,
1341                                          len, copied, page, fsdata);
1342         /*
1343          * it's important to update i_size while still holding page lock:
1344          * page writeout could otherwise come in and zero beyond i_size.
1345          */
1346         i_size_changed = ext4_update_inode_size(inode, pos + copied);
1347         unlock_page(page);
1348         put_page(page);
1349 
1350         if (old_size < pos)
1351                 pagecache_isize_extended(inode, old_size, pos);
1352         /*
1353          * Don't mark the inode dirty under page lock. First, it unnecessarily
1354          * makes the holding time of page lock longer. Second, it forces lock
1355          * ordering of page lock and transaction start for journaling
1356          * filesystems.
1357          */
1358         if (i_size_changed)
1359                 ext4_mark_inode_dirty(handle, inode);
1360 
1361         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1362                 /* if we have allocated more blocks and copied
1363                  * less. We will have blocks allocated outside
1364                  * inode->i_size. So truncate them
1365                  */
1366                 ext4_orphan_add(handle, inode);
1367 errout:
1368         ret2 = ext4_journal_stop(handle);
1369         if (!ret)
1370                 ret = ret2;
1371 
1372         if (pos + len > inode->i_size) {
1373                 ext4_truncate_failed_write(inode);
1374                 /*
1375                  * If truncate failed early the inode might still be
1376                  * on the orphan list; we need to make sure the inode
1377                  * is removed from the orphan list in that case.
1378                  */
1379                 if (inode->i_nlink)
1380                         ext4_orphan_del(NULL, inode);
1381         }
1382 
1383         return ret ? ret : copied;
1384 }
1385 
1386 /*
1387  * This is a private version of page_zero_new_buffers() which doesn't
1388  * set the buffer to be dirty, since in data=journalled mode we need
1389  * to call ext4_handle_dirty_metadata() instead.
1390  */
1391 static void ext4_journalled_zero_new_buffers(handle_t *handle,
1392                                             struct page *page,
1393                                             unsigned from, unsigned to)
1394 {
1395         unsigned int block_start = 0, block_end;
1396         struct buffer_head *head, *bh;
1397 
1398         bh = head = page_buffers(page);
1399         do {
1400                 block_end = block_start + bh->b_size;
1401                 if (buffer_new(bh)) {
1402                         if (block_end > from && block_start < to) {
1403                                 if (!PageUptodate(page)) {
1404                                         unsigned start, size;
1405 
1406                                         start = max(from, block_start);
1407                                         size = min(to, block_end) - start;
1408 
1409                                         zero_user(page, start, size);
1410                                         write_end_fn(handle, bh);
1411                                 }
1412                                 clear_buffer_new(bh);
1413                         }
1414                 }
1415                 block_start = block_end;
1416                 bh = bh->b_this_page;
1417         } while (bh != head);
1418 }
1419 
1420 static int ext4_journalled_write_end(struct file *file,
1421                                      struct address_space *mapping,
1422                                      loff_t pos, unsigned len, unsigned copied,
1423                                      struct page *page, void *fsdata)
1424 {
1425         handle_t *handle = ext4_journal_current_handle();
1426         struct inode *inode = mapping->host;
1427         loff_t old_size = inode->i_size;
1428         int ret = 0, ret2;
1429         int partial = 0;
1430         unsigned from, to;
1431         int size_changed = 0;
1432 
1433         trace_ext4_journalled_write_end(inode, pos, len, copied);
1434         from = pos & (PAGE_SIZE - 1);
1435         to = from + len;
1436 
1437         BUG_ON(!ext4_handle_valid(handle));
1438 
1439         if (ext4_has_inline_data(inode)) {
1440                 ret = ext4_write_inline_data_end(inode, pos, len,
1441                                                  copied, page);
1442                 if (ret < 0) {
1443                         unlock_page(page);
1444                         put_page(page);
1445                         goto errout;
1446                 }
1447                 copied = ret;
1448         } else if (unlikely(copied < len) && !PageUptodate(page)) {
1449                 copied = 0;
1450                 ext4_journalled_zero_new_buffers(handle, page, from, to);
1451         } else {
1452                 if (unlikely(copied < len))
1453                         ext4_journalled_zero_new_buffers(handle, page,
1454                                                          from + copied, to);
1455                 ret = ext4_walk_page_buffers(handle, page_buffers(page), from,
1456                                              from + copied, &partial,
1457                                              write_end_fn);
1458                 if (!partial)
1459                         SetPageUptodate(page);
1460         }
1461         size_changed = ext4_update_inode_size(inode, pos + copied);
1462         ext4_set_inode_state(inode, EXT4_STATE_JDATA);
1463         EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
1464         unlock_page(page);
1465         put_page(page);
1466 
1467         if (old_size < pos)
1468                 pagecache_isize_extended(inode, old_size, pos);
1469 
1470         if (size_changed) {
1471                 ret2 = ext4_mark_inode_dirty(handle, inode);
1472                 if (!ret)
1473                         ret = ret2;
1474         }
1475 
1476         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1477                 /* if we have allocated more blocks and copied
1478                  * less. We will have blocks allocated outside
1479                  * inode->i_size. So truncate them
1480                  */
1481                 ext4_orphan_add(handle, inode);
1482 
1483 errout:
1484         ret2 = ext4_journal_stop(handle);
1485         if (!ret)
1486                 ret = ret2;
1487         if (pos + len > inode->i_size) {
1488                 ext4_truncate_failed_write(inode);
1489                 /*
1490                  * If truncate failed early the inode might still be
1491                  * on the orphan list; we need to make sure the inode
1492                  * is removed from the orphan list in that case.
1493                  */
1494                 if (inode->i_nlink)
1495                         ext4_orphan_del(NULL, inode);
1496         }
1497 
1498         return ret ? ret : copied;
1499 }
1500 
1501 /*
1502  * Reserve space for a single cluster
1503  */
1504 static int ext4_da_reserve_space(struct inode *inode)
1505 {
1506         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1507         struct ext4_inode_info *ei = EXT4_I(inode);
1508         int ret;
1509 
1510         /*
1511          * We will charge metadata quota at writeout time; this saves
1512          * us from metadata over-estimation, though we may go over by
1513          * a small amount in the end.  Here we just reserve for data.
1514          */
1515         ret = dquot_reserve_block(inode, EXT4_C2B(sbi, 1));
1516         if (ret)
1517                 return ret;
1518 
1519         spin_lock(&ei->i_block_reservation_lock);
1520         if (ext4_claim_free_clusters(sbi, 1, 0)) {
1521                 spin_unlock(&ei->i_block_reservation_lock);
1522                 dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
1523                 return -ENOSPC;
1524         }
1525         ei->i_reserved_data_blocks++;
1526         trace_ext4_da_reserve_space(inode);
1527         spin_unlock(&ei->i_block_reservation_lock);
1528 
1529         return 0;       /* success */
1530 }
1531 
1532 static void ext4_da_release_space(struct inode *inode, int to_free)
1533 {
1534         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1535         struct ext4_inode_info *ei = EXT4_I(inode);
1536 
1537         if (!to_free)
1538                 return;         /* Nothing to release, exit */
1539 
1540         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1541 
1542         trace_ext4_da_release_space(inode, to_free);
1543         if (unlikely(to_free > ei->i_reserved_data_blocks)) {
1544                 /*
1545                  * if there aren't enough reserved blocks, then the
1546                  * counter is messed up somewhere.  Since this
1547                  * function is called from invalidate page, it's
1548                  * harmless to return without any action.
1549                  */
1550                 ext4_warning(inode->i_sb, "ext4_da_release_space: "
1551                          "ino %lu, to_free %d with only %d reserved "
1552                          "data blocks", inode->i_ino, to_free,
1553                          ei->i_reserved_data_blocks);
1554                 WARN_ON(1);
1555                 to_free = ei->i_reserved_data_blocks;
1556         }
1557         ei->i_reserved_data_blocks -= to_free;
1558 
1559         /* update fs dirty data blocks counter */
1560         percpu_counter_sub(&sbi->s_dirtyclusters_counter, to_free);
1561 
1562         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1563 
1564         dquot_release_reservation_block(inode, EXT4_C2B(sbi, to_free));
1565 }
1566 
1567 static void ext4_da_page_release_reservation(struct page *page,
1568                                              unsigned int offset,
1569                                              unsigned int length)
1570 {
1571         int to_release = 0, contiguous_blks = 0;
1572         struct buffer_head *head, *bh;
1573         unsigned int curr_off = 0;
1574         struct inode *inode = page->mapping->host;
1575         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1576         unsigned int stop = offset + length;
1577         int num_clusters;
1578         ext4_fsblk_t lblk;
1579 
1580         BUG_ON(stop > PAGE_SIZE || stop < length);
1581 
1582         head = page_buffers(page);
1583         bh = head;
1584         do {
1585                 unsigned int next_off = curr_off + bh->b_size;
1586 
1587                 if (next_off > stop)
1588                         break;
1589 
1590                 if ((offset <= curr_off) && (buffer_delay(bh))) {
1591                         to_release++;
1592                         contiguous_blks++;
1593                         clear_buffer_delay(bh);
1594                 } else if (contiguous_blks) {
1595                         lblk = page->index <<
1596                                (PAGE_SHIFT - inode->i_blkbits);
1597                         lblk += (curr_off >> inode->i_blkbits) -
1598                                 contiguous_blks;
1599                         ext4_es_remove_extent(inode, lblk, contiguous_blks);
1600                         contiguous_blks = 0;
1601                 }
1602                 curr_off = next_off;
1603         } while ((bh = bh->b_this_page) != head);
1604 
1605         if (contiguous_blks) {
1606                 lblk = page->index << (PAGE_SHIFT - inode->i_blkbits);
1607                 lblk += (curr_off >> inode->i_blkbits) - contiguous_blks;
1608                 ext4_es_remove_extent(inode, lblk, contiguous_blks);
1609         }
1610 
1611         /* If we have released all the blocks belonging to a cluster, then we
1612          * need to release the reserved space for that cluster. */
1613         num_clusters = EXT4_NUM_B2C(sbi, to_release);
1614         while (num_clusters > 0) {
1615                 lblk = (page->index << (PAGE_SHIFT - inode->i_blkbits)) +
1616                         ((num_clusters - 1) << sbi->s_cluster_bits);
1617                 if (sbi->s_cluster_ratio == 1 ||
1618                     !ext4_find_delalloc_cluster(inode, lblk))
1619                         ext4_da_release_space(inode, 1);
1620 
1621                 num_clusters--;
1622         }
1623 }
1624 
1625 /*
1626  * Delayed allocation stuff
1627  */
1628 
1629 struct mpage_da_data {
1630         struct inode *inode;
1631         struct writeback_control *wbc;
1632 
1633         pgoff_t first_page;     /* The first page to write */
1634         pgoff_t next_page;      /* Current page to examine */
1635         pgoff_t last_page;      /* Last page to examine */
1636         /*
1637          * Extent to map - this can be after first_page because that can be
1638          * fully mapped. We somewhat abuse m_flags to store whether the extent
1639          * is delalloc or unwritten.
1640          */
1641         struct ext4_map_blocks map;
1642         struct ext4_io_submit io_submit;        /* IO submission data */
1643 };
1644 
1645 static void mpage_release_unused_pages(struct mpage_da_data *mpd,
1646                                        bool invalidate)
1647 {
1648         int nr_pages, i;
1649         pgoff_t index, end;
1650         struct pagevec pvec;
1651         struct inode *inode = mpd->inode;
1652         struct address_space *mapping = inode->i_mapping;
1653 
1654         /* This is necessary when next_page == 0. */
1655         if (mpd->first_page >= mpd->next_page)
1656                 return;
1657 
1658         index = mpd->first_page;
1659         end   = mpd->next_page - 1;
1660         if (invalidate) {
1661                 ext4_lblk_t start, last;
1662                 start = index << (PAGE_SHIFT - inode->i_blkbits);
1663                 last = end << (PAGE_SHIFT - inode->i_blkbits);
1664                 ext4_es_remove_extent(inode, start, last - start + 1);
1665         }
1666 
1667         pagevec_init(&pvec, 0);
1668         while (index <= end) {
1669                 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
1670                 if (nr_pages == 0)
1671                         break;
1672                 for (i = 0; i < nr_pages; i++) {
1673                         struct page *page = pvec.pages[i];
1674                         if (page->index > end)
1675                                 break;
1676                         BUG_ON(!PageLocked(page));
1677                         BUG_ON(PageWriteback(page));
1678                         if (invalidate) {
1679                                 if (page_mapped(page))
1680                                         clear_page_dirty_for_io(page);
1681                                 block_invalidatepage(page, 0, PAGE_SIZE);
1682                                 ClearPageUptodate(page);
1683                         }
1684                         unlock_page(page);
1685                 }
1686                 index = pvec.pages[nr_pages - 1]->index + 1;
1687                 pagevec_release(&pvec);
1688         }
1689 }
1690 
1691 static void ext4_print_free_blocks(struct inode *inode)
1692 {
1693         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1694         struct super_block *sb = inode->i_sb;
1695         struct ext4_inode_info *ei = EXT4_I(inode);
1696 
1697         ext4_msg(sb, KERN_CRIT, "Total free blocks count %lld",
1698                EXT4_C2B(EXT4_SB(inode->i_sb),
1699                         ext4_count_free_clusters(sb)));
1700         ext4_msg(sb, KERN_CRIT, "Free/Dirty block details");
1701         ext4_msg(sb, KERN_CRIT, "free_blocks=%lld",
1702                (long long) EXT4_C2B(EXT4_SB(sb),
1703                 percpu_counter_sum(&sbi->s_freeclusters_counter)));
1704         ext4_msg(sb, KERN_CRIT, "dirty_blocks=%lld",
1705                (long long) EXT4_C2B(EXT4_SB(sb),
1706                 percpu_counter_sum(&sbi->s_dirtyclusters_counter)));
1707         ext4_msg(sb, KERN_CRIT, "Block reservation details");
1708         ext4_msg(sb, KERN_CRIT, "i_reserved_data_blocks=%u",
1709                  ei->i_reserved_data_blocks);
1710         return;
1711 }
1712 
1713 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh)
1714 {
1715         return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh);
1716 }
1717 
1718 /*
1719  * This function is grabs code from the very beginning of
1720  * ext4_map_blocks, but assumes that the caller is from delayed write
1721  * time. This function looks up the requested blocks and sets the
1722  * buffer delay bit under the protection of i_data_sem.
1723  */
1724 static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
1725                               struct ext4_map_blocks *map,
1726                               struct buffer_head *bh)
1727 {
1728         struct extent_status es;
1729         int retval;
1730         sector_t invalid_block = ~((sector_t) 0xffff);
1731 #ifdef ES_AGGRESSIVE_TEST
1732         struct ext4_map_blocks orig_map;
1733 
1734         memcpy(&orig_map, map, sizeof(*map));
1735 #endif
1736 
1737         if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
1738                 invalid_block = ~0;
1739 
1740         map->m_flags = 0;
1741         ext_debug("ext4_da_map_blocks(): inode %lu, max_blocks %u,"
1742                   "logical block %lu\n", inode->i_ino, map->m_len,
1743                   (unsigned long) map->m_lblk);
1744 
1745         /* Lookup extent status tree firstly */
1746         if (ext4_es_lookup_extent(inode, iblock, &es)) {
1747                 if (ext4_es_is_hole(&es)) {
1748                         retval = 0;
1749                         down_read(&EXT4_I(inode)->i_data_sem);
1750                         goto add_delayed;
1751                 }
1752 
1753                 /*
1754                  * Delayed extent could be allocated by fallocate.
1755                  * So we need to check it.
1756                  */
1757                 if (ext4_es_is_delayed(&es) && !ext4_es_is_unwritten(&es)) {
1758                         map_bh(bh, inode->i_sb, invalid_block);
1759                         set_buffer_new(bh);
1760                         set_buffer_delay(bh);
1761                         return 0;
1762                 }
1763 
1764                 map->m_pblk = ext4_es_pblock(&es) + iblock - es.es_lblk;
1765                 retval = es.es_len - (iblock - es.es_lblk);
1766                 if (retval > map->m_len)
1767                         retval = map->m_len;
1768                 map->m_len = retval;
1769                 if (ext4_es_is_written(&es))
1770                         map->m_flags |= EXT4_MAP_MAPPED;
1771                 else if (ext4_es_is_unwritten(&es))
1772                         map->m_flags |= EXT4_MAP_UNWRITTEN;
1773                 else
1774                         BUG_ON(1);
1775 
1776 #ifdef ES_AGGRESSIVE_TEST
1777                 ext4_map_blocks_es_recheck(NULL, inode, map, &orig_map, 0);
1778 #endif
1779                 return retval;
1780         }
1781 
1782         /*
1783          * Try to see if we can get the block without requesting a new
1784          * file system block.
1785          */
1786         down_read(&EXT4_I(inode)->i_data_sem);
1787         if (ext4_has_inline_data(inode))
1788                 retval = 0;
1789         else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
1790                 retval = ext4_ext_map_blocks(NULL, inode, map, 0);
1791         else
1792                 retval = ext4_ind_map_blocks(NULL, inode, map, 0);
1793 
1794 add_delayed:
1795         if (retval == 0) {
1796                 int ret;
1797                 /*
1798                  * XXX: __block_prepare_write() unmaps passed block,
1799                  * is it OK?
1800                  */
1801                 /*
1802                  * If the block was allocated from previously allocated cluster,
1803                  * then we don't need to reserve it again. However we still need
1804                  * to reserve metadata for every block we're going to write.
1805                  */
1806                 if (EXT4_SB(inode->i_sb)->s_cluster_ratio == 1 ||
1807                     !ext4_find_delalloc_cluster(inode, map->m_lblk)) {
1808                         ret = ext4_da_reserve_space(inode);
1809                         if (ret) {
1810                                 /* not enough space to reserve */
1811                                 retval = ret;
1812                                 goto out_unlock;
1813                         }
1814                 }
1815 
1816                 ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
1817                                             ~0, EXTENT_STATUS_DELAYED);
1818                 if (ret) {
1819                         retval = ret;
1820                         goto out_unlock;
1821                 }
1822 
1823                 map_bh(bh, inode->i_sb, invalid_block);
1824                 set_buffer_new(bh);
1825                 set_buffer_delay(bh);
1826         } else if (retval > 0) {
1827                 int ret;
1828                 unsigned int status;
1829 
1830                 if (unlikely(retval != map->m_len)) {
1831                         ext4_warning(inode->i_sb,
1832                                      "ES len assertion failed for inode "
1833                                      "%lu: retval %d != map->m_len %d",
1834                                      inode->i_ino, retval, map->m_len);
1835                         WARN_ON(1);
1836                 }
1837 
1838                 status = map->m_flags & EXT4_MAP_UNWRITTEN ?
1839                                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
1840                 ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
1841                                             map->m_pblk, status);
1842                 if (ret != 0)
1843                         retval = ret;
1844         }
1845 
1846 out_unlock:
1847         up_read((&EXT4_I(inode)->i_data_sem));
1848 
1849         return retval;
1850 }
1851 
1852 /*
1853  * This is a special get_block_t callback which is used by
1854  * ext4_da_write_begin().  It will either return mapped block or
1855  * reserve space for a single block.
1856  *
1857  * For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
1858  * We also have b_blocknr = -1 and b_bdev initialized properly
1859  *
1860  * For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
1861  * We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
1862  * initialized properly.
1863  */
1864 int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
1865                            struct buffer_head *bh, int create)
1866 {
1867         struct ext4_map_blocks map;
1868         int ret = 0;
1869 
1870         BUG_ON(create == 0);
1871         BUG_ON(bh->b_size != inode->i_sb->s_blocksize);
1872 
1873         map.m_lblk = iblock;
1874         map.m_len = 1;
1875 
1876         /*
1877          * first, we need to know whether the block is allocated already
1878          * preallocated blocks are unmapped but should treated
1879          * the same as allocated blocks.
1880          */
1881         ret = ext4_da_map_blocks(inode, iblock, &map, bh);
1882         if (ret <= 0)
1883                 return ret;
1884 
1885         map_bh(bh, inode->i_sb, map.m_pblk);
1886         ext4_update_bh_state(bh, map.m_flags);
1887 
1888         if (buffer_unwritten(bh)) {
1889                 /* A delayed write to unwritten bh should be marked
1890                  * new and mapped.  Mapped ensures that we don't do
1891                  * get_block multiple times when we write to the same
1892                  * offset and new ensures that we do proper zero out
1893                  * for partial write.
1894                  */
1895                 set_buffer_new(bh);
1896                 set_buffer_mapped(bh);
1897         }
1898         return 0;
1899 }
1900 
1901 static int bget_one(handle_t *handle, struct buffer_head *bh)
1902 {
1903         get_bh(bh);
1904         return 0;
1905 }
1906 
1907 static int bput_one(handle_t *handle, struct buffer_head *bh)
1908 {
1909         put_bh(bh);
1910         return 0;
1911 }
1912 
1913 static int __ext4_journalled_writepage(struct page *page,
1914                                        unsigned int len)
1915 {
1916         struct address_space *mapping = page->mapping;
1917         struct inode *inode = mapping->host;
1918         struct buffer_head *page_bufs = NULL;
1919         handle_t *handle = NULL;
1920         int ret = 0, err = 0;
1921         int inline_data = ext4_has_inline_data(inode);
1922         struct buffer_head *inode_bh = NULL;
1923 
1924         ClearPageChecked(page);
1925 
1926         if (inline_data) {
1927                 BUG_ON(page->index != 0);
1928                 BUG_ON(len > ext4_get_max_inline_size(inode));
1929                 inode_bh = ext4_journalled_write_inline_data(inode, len, page);
1930                 if (inode_bh == NULL)
1931                         goto out;
1932         } else {
1933                 page_bufs = page_buffers(page);
1934                 if (!page_bufs) {
1935                         BUG();
1936                         goto out;
1937                 }
1938                 ext4_walk_page_buffers(handle, page_bufs, 0, len,
1939                                        NULL, bget_one);
1940         }
1941         /*
1942          * We need to release the page lock before we start the
1943          * journal, so grab a reference so the page won't disappear
1944          * out from under us.
1945          */
1946         get_page(page);
1947         unlock_page(page);
1948 
1949         handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
1950                                     ext4_writepage_trans_blocks(inode));
1951         if (IS_ERR(handle)) {
1952                 ret = PTR_ERR(handle);
1953                 put_page(page);
1954                 goto out_no_pagelock;
1955         }
1956         BUG_ON(!ext4_handle_valid(handle));
1957 
1958         lock_page(page);
1959         put_page(page);
1960         if (page->mapping != mapping) {
1961                 /* The page got truncated from under us */
1962                 ext4_journal_stop(handle);
1963                 ret = 0;
1964                 goto out;
1965         }
1966 
1967         if (inline_data) {
1968                 BUFFER_TRACE(inode_bh, "get write access");
1969                 ret = ext4_journal_get_write_access(handle, inode_bh);
1970 
1971                 err = ext4_handle_dirty_metadata(handle, inode, inode_bh);
1972 
1973         } else {
1974                 ret = ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL,
1975                                              do_journal_get_write_access);
1976 
1977                 err = ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL,
1978                                              write_end_fn);
1979         }
1980         if (ret == 0)
1981                 ret = err;
1982         EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
1983         err = ext4_journal_stop(handle);
1984         if (!ret)
1985                 ret = err;
1986 
1987         if (!ext4_has_inline_data(inode))
1988                 ext4_walk_page_buffers(NULL, page_bufs, 0, len,
1989                                        NULL, bput_one);
1990         ext4_set_inode_state(inode, EXT4_STATE_JDATA);
1991 out:
1992         unlock_page(page);
1993 out_no_pagelock:
1994         brelse(inode_bh);
1995         return ret;
1996 }
1997 
1998 /*
1999  * Note that we don't need to start a transaction unless we're journaling data
2000  * because we should have holes filled from ext4_page_mkwrite(). We even don't
2001  * need to file the inode to the transaction's list in ordered mode because if
2002  * we are writing back data added by write(), the inode is already there and if
2003  * we are writing back data modified via mmap(), no one guarantees in which
2004  * transaction the data will hit the disk. In case we are journaling data, we
2005  * cannot start transaction directly because transaction start ranks above page
2006  * lock so we have to do some magic.
2007  *
2008  * This function can get called via...
2009  *   - ext4_writepages after taking page lock (have journal handle)
2010  *   - journal_submit_inode_data_buffers (no journal handle)
2011  *   - shrink_page_list via the kswapd/direct reclaim (no journal handle)
2012  *   - grab_page_cache when doing write_begin (have journal handle)
2013  *
2014  * We don't do any block allocation in this function. If we have page with
2015  * multiple blocks we need to write those buffer_heads that are mapped. This
2016  * is important for mmaped based write. So if we do with blocksize 1K
2017  * truncate(f, 1024);
2018  * a = mmap(f, 0, 4096);
2019  * a[0] = 'a';
2020  * truncate(f, 4096);
2021  * we have in the page first buffer_head mapped via page_mkwrite call back
2022  * but other buffer_heads would be unmapped but dirty (dirty done via the
2023  * do_wp_page). So writepage should write the first block. If we modify
2024  * the mmap area beyond 1024 we will again get a page_fault and the
2025  * page_mkwrite callback will do the block allocation and mark the
2026  * buffer_heads mapped.
2027  *
2028  * We redirty the page if we have any buffer_heads that is either delay or
2029  * unwritten in the page.
2030  *
2031  * We can get recursively called as show below.
2032  *
2033  *      ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
2034  *              ext4_writepage()
2035  *
2036  * But since we don't do any block allocation we should not deadlock.
2037  * Page also have the dirty flag cleared so we don't get recurive page_lock.
2038  */
2039 static int ext4_writepage(struct page *page,
2040                           struct writeback_control *wbc)
2041 {
2042         int ret = 0;
2043         loff_t size;
2044         unsigned int len;
2045         struct buffer_head *page_bufs = NULL;
2046         struct inode *inode = page->mapping->host;
2047         struct ext4_io_submit io_submit;
2048         bool keep_towrite = false;
2049 
2050         trace_ext4_writepage(page);
2051         size = i_size_read(inode);
2052         if (page->index == size >> PAGE_SHIFT)
2053                 len = size & ~PAGE_MASK;
2054         else
2055                 len = PAGE_SIZE;
2056 
2057         page_bufs = page_buffers(page);
2058         /*
2059          * We cannot do block allocation or other extent handling in this
2060          * function. If there are buffers needing that, we have to redirty
2061          * the page. But we may reach here when we do a journal commit via
2062          * journal_submit_inode_data_buffers() and in that case we must write
2063          * allocated buffers to achieve data=ordered mode guarantees.
2064          *
2065          * Also, if there is only one buffer per page (the fs block
2066          * size == the page size), if one buffer needs block
2067          * allocation or needs to modify the extent tree to clear the
2068          * unwritten flag, we know that the page can't be written at
2069          * all, so we might as well refuse the write immediately.
2070          * Unfortunately if the block size != page size, we can't as
2071          * easily detect this case using ext4_walk_page_buffers(), but
2072          * for the extremely common case, this is an optimization that
2073          * skips a useless round trip through ext4_bio_write_page().
2074          */
2075         if (ext4_walk_page_buffers(NULL, page_bufs, 0, len, NULL,
2076                                    ext4_bh_delay_or_unwritten)) {
2077                 redirty_page_for_writepage(wbc, page);
2078                 if ((current->flags & PF_MEMALLOC) ||
2079                     (inode->i_sb->s_blocksize == PAGE_SIZE)) {
2080                         /*
2081                          * For memory cleaning there's no point in writing only
2082                          * some buffers. So just bail out. Warn if we came here
2083                          * from direct reclaim.
2084                          */
2085                         WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD))
2086                                                         == PF_MEMALLOC);
2087                         unlock_page(page);
2088                         return 0;
2089                 }
2090                 keep_towrite = true;
2091         }
2092 
2093         if (PageChecked(page) && ext4_should_journal_data(inode))
2094                 /*
2095                  * It's mmapped pagecache.  Add buffers and journal it.  There
2096                  * doesn't seem much point in redirtying the page here.
2097                  */
2098                 return __ext4_journalled_writepage(page, len);
2099 
2100         ext4_io_submit_init(&io_submit, wbc);
2101         io_submit.io_end = ext4_init_io_end(inode, GFP_NOFS);
2102         if (!io_submit.io_end) {
2103                 redirty_page_for_writepage(wbc, page);
2104                 unlock_page(page);
2105                 return -ENOMEM;
2106         }
2107         ret = ext4_bio_write_page(&io_submit, page, len, wbc, keep_towrite);
2108         ext4_io_submit(&io_submit);
2109         /* Drop io_end reference we got from init */
2110         ext4_put_io_end_defer(io_submit.io_end);
2111         return ret;
2112 }
2113 
2114 static int mpage_submit_page(struct mpage_da_data *mpd, struct page *page)
2115 {
2116         int len;
2117         loff_t size = i_size_read(mpd->inode);
2118         int err;
2119 
2120         BUG_ON(page->index != mpd->first_page);
2121         if (page->index == size >> PAGE_SHIFT)
2122                 len = size & ~PAGE_MASK;
2123         else
2124                 len = PAGE_SIZE;
2125         clear_page_dirty_for_io(page);
2126         err = ext4_bio_write_page(&mpd->io_submit, page, len, mpd->wbc, false);
2127         if (!err)
2128                 mpd->wbc->nr_to_write--;
2129         mpd->first_page++;
2130 
2131         return err;
2132 }
2133 
2134 #define BH_FLAGS ((1 << BH_Unwritten) | (1 << BH_Delay))
2135 
2136 /*
2137  * mballoc gives us at most this number of blocks...
2138  * XXX: That seems to be only a limitation of ext4_mb_normalize_request().
2139  * The rest of mballoc seems to handle chunks up to full group size.
2140  */
2141 #define MAX_WRITEPAGES_EXTENT_LEN 2048
2142 
2143 /*
2144  * mpage_add_bh_to_extent - try to add bh to extent of blocks to map
2145  *
2146  * @mpd - extent of blocks
2147  * @lblk - logical number of the block in the file
2148  * @bh - buffer head we want to add to the extent
2149  *
2150  * The function is used to collect contig. blocks in the same state. If the
2151  * buffer doesn't require mapping for writeback and we haven't started the
2152  * extent of buffers to map yet, the function returns 'true' immediately - the
2153  * caller can write the buffer right away. Otherwise the function returns true
2154  * if the block has been added to the extent, false if the block couldn't be
2155  * added.
2156  */
2157 static bool mpage_add_bh_to_extent(struct mpage_da_data *mpd, ext4_lblk_t lblk,
2158                                    struct buffer_head *bh)
2159 {
2160         struct ext4_map_blocks *map = &mpd->map;
2161 
2162         /* Buffer that doesn't need mapping for writeback? */
2163         if (!buffer_dirty(bh) || !buffer_mapped(bh) ||
2164             (!buffer_delay(bh) && !buffer_unwritten(bh))) {
2165                 /* So far no extent to map => we write the buffer right away */
2166                 if (map->m_len == 0)
2167                         return true;
2168                 return false;
2169         }
2170 
2171         /* First block in the extent? */
2172         if (map->m_len == 0) {
2173                 map->m_lblk = lblk;
2174                 map->m_len = 1;
2175                 map->m_flags = bh->b_state & BH_FLAGS;
2176                 return true;
2177         }
2178 
2179         /* Don't go larger than mballoc is willing to allocate */
2180         if (map->m_len >= MAX_WRITEPAGES_EXTENT_LEN)
2181                 return false;
2182 
2183         /* Can we merge the block to our big extent? */
2184         if (lblk == map->m_lblk + map->m_len &&
2185             (bh->b_state & BH_FLAGS) == map->m_flags) {
2186                 map->m_len++;
2187                 return true;
2188         }
2189         return false;
2190 }
2191 
2192 /*
2193  * mpage_process_page_bufs - submit page buffers for IO or add them to extent
2194  *
2195  * @mpd - extent of blocks for mapping
2196  * @head - the first buffer in the page
2197  * @bh - buffer we should start processing from
2198  * @lblk - logical number of the block in the file corresponding to @bh
2199  *
2200  * Walk through page buffers from @bh upto @head (exclusive) and either submit
2201  * the page for IO if all buffers in this page were mapped and there's no
2202  * accumulated extent of buffers to map or add buffers in the page to the
2203  * extent of buffers to map. The function returns 1 if the caller can continue
2204  * by processing the next page, 0 if it should stop adding buffers to the
2205  * extent to map because we cannot extend it anymore. It can also return value
2206  * < 0 in case of error during IO submission.
2207  */
2208 static int mpage_process_page_bufs(struct mpage_da_data *mpd,
2209                                    struct buffer_head *head,
2210                                    struct buffer_head *bh,
2211                                    ext4_lblk_t lblk)
2212 {
2213         struct inode *inode = mpd->inode;
2214         int err;
2215         ext4_lblk_t blocks = (i_size_read(inode) + (1 << inode->i_blkbits) - 1)
2216                                                         >> inode->i_blkbits;
2217 
2218         do {
2219                 BUG_ON(buffer_locked(bh));
2220 
2221                 if (lblk >= blocks || !mpage_add_bh_to_extent(mpd, lblk, bh)) {
2222                         /* Found extent to map? */
2223                         if (mpd->map.m_len)
2224                                 return 0;
2225                         /* Everything mapped so far and we hit EOF */
2226                         break;
2227                 }
2228         } while (lblk++, (bh = bh->b_this_page) != head);
2229         /* So far everything mapped? Submit the page for IO. */
2230         if (mpd->map.m_len == 0) {
2231                 err = mpage_submit_page(mpd, head->b_page);
2232                 if (err < 0)
2233                         return err;
2234         }
2235         return lblk < blocks;
2236 }
2237 
2238 /*
2239  * mpage_map_buffers - update buffers corresponding to changed extent and
2240  *                     submit fully mapped pages for IO
2241  *
2242  * @mpd - description of extent to map, on return next extent to map
2243  *
2244  * Scan buffers corresponding to changed extent (we expect corresponding pages
2245  * to be already locked) and update buffer state according to new extent state.
2246  * We map delalloc buffers to their physical location, clear unwritten bits,
2247  * and mark buffers as uninit when we perform writes to unwritten extents
2248  * and do extent conversion after IO is finished. If the last page is not fully
2249  * mapped, we update @map to the next extent in the last page that needs
2250  * mapping. Otherwise we submit the page for IO.
2251  */
2252 static int mpage_map_and_submit_buffers(struct mpage_da_data *mpd)
2253 {
2254         struct pagevec pvec;
2255         int nr_pages, i;
2256         struct inode *inode = mpd->inode;
2257         struct buffer_head *head, *bh;
2258         int bpp_bits = PAGE_SHIFT - inode->i_blkbits;
2259         pgoff_t start, end;
2260         ext4_lblk_t lblk;
2261         sector_t pblock;
2262         int err;
2263 
2264         start = mpd->map.m_lblk >> bpp_bits;
2265         end = (mpd->map.m_lblk + mpd->map.m_len - 1) >> bpp_bits;
2266         lblk = start << bpp_bits;
2267         pblock = mpd->map.m_pblk;
2268 
2269         pagevec_init(&pvec, 0);
2270         while (start <= end) {
2271                 nr_pages = pagevec_lookup(&pvec, inode->i_mapping, start,
2272                                           PAGEVEC_SIZE);
2273                 if (nr_pages == 0)
2274                         break;
2275                 for (i = 0; i < nr_pages; i++) {
2276                         struct page *page = pvec.pages[i];
2277 
2278                         if (page->index > end)
2279                                 break;
2280                         /* Up to 'end' pages must be contiguous */
2281                         BUG_ON(page->index != start);
2282                         bh = head = page_buffers(page);
2283                         do {
2284                                 if (lblk < mpd->map.m_lblk)
2285                                         continue;
2286                                 if (lblk >= mpd->map.m_lblk + mpd->map.m_len) {
2287                                         /*
2288                                          * Buffer after end of mapped extent.
2289                                          * Find next buffer in the page to map.
2290                                          */
2291                                         mpd->map.m_len = 0;
2292                                         mpd->map.m_flags = 0;
2293                                         /*
2294                                          * FIXME: If dioread_nolock supports
2295                                          * blocksize < pagesize, we need to make
2296                                          * sure we add size mapped so far to
2297                                          * io_end->size as the following call
2298                                          * can submit the page for IO.
2299                                          */
2300                                         err = mpage_process_page_bufs(mpd, head,
2301                                                                       bh, lblk);
2302                                         pagevec_release(&pvec);
2303                                         if (err > 0)
2304                                                 err = 0;
2305                                         return err;
2306                                 }
2307                                 if (buffer_delay(bh)) {
2308                                         clear_buffer_delay(bh);
2309                                         bh->b_blocknr = pblock++;
2310                                 }
2311                                 clear_buffer_unwritten(bh);
2312                         } while (lblk++, (bh = bh->b_this_page) != head);
2313 
2314                         /*
2315                          * FIXME: This is going to break if dioread_nolock
2316                          * supports blocksize < pagesize as we will try to
2317                          * convert potentially unmapped parts of inode.
2318                          */
2319                         mpd->io_submit.io_end->size += PAGE_SIZE;
2320                         /* Page fully mapped - let IO run! */
2321                         err = mpage_submit_page(mpd, page);
2322                         if (err < 0) {
2323                                 pagevec_release(&pvec);
2324                                 return err;
2325                         }
2326                         start++;
2327                 }
2328                 pagevec_release(&pvec);
2329         }
2330         /* Extent fully mapped and matches with page boundary. We are done. */
2331         mpd->map.m_len = 0;
2332         mpd->map.m_flags = 0;
2333         return 0;
2334 }
2335 
2336 static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
2337 {
2338         struct inode *inode = mpd->inode;
2339         struct ext4_map_blocks *map = &mpd->map;
2340         int get_blocks_flags;
2341         int err, dioread_nolock;
2342 
2343         trace_ext4_da_write_pages_extent(inode, map);
2344         /*
2345          * Call ext4_map_blocks() to allocate any delayed allocation blocks, or
2346          * to convert an unwritten extent to be initialized (in the case
2347          * where we have written into one or more preallocated blocks).  It is
2348          * possible that we're going to need more metadata blocks than
2349          * previously reserved. However we must not fail because we're in
2350          * writeback and there is nothing we can do about it so it might result
2351          * in data loss.  So use reserved blocks to allocate metadata if
2352          * possible.
2353          *
2354          * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE if
2355          * the blocks in question are delalloc blocks.  This indicates
2356          * that the blocks and quotas has already been checked when
2357          * the data was copied into the page cache.
2358          */
2359         get_blocks_flags = EXT4_GET_BLOCKS_CREATE |
2360                            EXT4_GET_BLOCKS_METADATA_NOFAIL |
2361                            EXT4_GET_BLOCKS_IO_SUBMIT;
2362         dioread_nolock = ext4_should_dioread_nolock(inode);
2363         if (dioread_nolock)
2364                 get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
2365         if (map->m_flags & (1 << BH_Delay))
2366                 get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
2367 
2368         err = ext4_map_blocks(handle, inode, map, get_blocks_flags);
2369         if (err < 0)
2370                 return err;
2371         if (dioread_nolock && (map->m_flags & EXT4_MAP_UNWRITTEN)) {
2372                 if (!mpd->io_submit.io_end->handle &&
2373                     ext4_handle_valid(handle)) {
2374                         mpd->io_submit.io_end->handle = handle->h_rsv_handle;
2375                         handle->h_rsv_handle = NULL;
2376                 }
2377                 ext4_set_io_unwritten_flag(inode, mpd->io_submit.io_end);
2378         }
2379 
2380         BUG_ON(map->m_len == 0);
2381         if (map->m_flags & EXT4_MAP_NEW) {
2382                 clean_bdev_aliases(inode->i_sb->s_bdev, map->m_pblk,
2383                                    map->m_len);
2384         }
2385         return 0;
2386 }
2387 
2388 /*
2389  * mpage_map_and_submit_extent - map extent starting at mpd->lblk of length
2390  *                               mpd->len and submit pages underlying it for IO
2391  *
2392  * @handle - handle for journal operations
2393  * @mpd - extent to map
2394  * @give_up_on_write - we set this to true iff there is a fatal error and there
2395  *                     is no hope of writing the data. The caller should discard
2396  *                     dirty pages to avoid infinite loops.
2397  *
2398  * The function maps extent starting at mpd->lblk of length mpd->len. If it is
2399  * delayed, blocks are allocated, if it is unwritten, we may need to convert
2400  * them to initialized or split the described range from larger unwritten
2401  * extent. Note that we need not map all the described range since allocation
2402  * can return less blocks or the range is covered by more unwritten extents. We
2403  * cannot map more because we are limited by reserved transaction credits. On
2404  * the other hand we always make sure that the last touched page is fully
2405  * mapped so that it can be written out (and thus forward progress is
2406  * guaranteed). After mapping we submit all mapped pages for IO.
2407  */
2408 static int mpage_map_and_submit_extent(handle_t *handle,
2409                                        struct mpage_da_data *mpd,
2410                                        bool *give_up_on_write)
2411 {
2412         struct inode *inode = mpd->inode;
2413         struct ext4_map_blocks *map = &mpd->map;
2414         int err;
2415         loff_t disksize;
2416         int progress = 0;
2417 
2418         mpd->io_submit.io_end->offset =
2419                                 ((loff_t)map->m_lblk) << inode->i_blkbits;
2420         do {
2421                 err = mpage_map_one_extent(handle, mpd);
2422                 if (err < 0) {
2423                         struct super_block *sb = inode->i_sb;
2424 
2425                         if (EXT4_SB(sb)->s_mount_flags & EXT4_MF_FS_ABORTED)
2426                                 goto invalidate_dirty_pages;
2427                         /*
2428                          * Let the uper layers retry transient errors.
2429                          * In the case of ENOSPC, if ext4_count_free_blocks()
2430                          * is non-zero, a commit should free up blocks.
2431                          */
2432                         if ((err == -ENOMEM) ||
2433                             (err == -ENOSPC && ext4_count_free_clusters(sb))) {
2434                                 if (progress)
2435                                         goto update_disksize;
2436                                 return err;
2437                         }
2438                         ext4_msg(sb, KERN_CRIT,
2439                                  "Delayed block allocation failed for "
2440                                  "inode %lu at logical offset %llu with"
2441                                  " max blocks %u with error %d",
2442                                  inode->i_ino,
2443                                  (unsigned long long)map->m_lblk,
2444                                  (unsigned)map->m_len, -err);
2445                         ext4_msg(sb, KERN_CRIT,
2446                                  "This should not happen!! Data will "
2447                                  "be lost\n");
2448                         if (err == -ENOSPC)
2449                                 ext4_print_free_blocks(inode);
2450                 invalidate_dirty_pages:
2451                         *give_up_on_write = true;
2452                         return err;
2453                 }
2454                 progress = 1;
2455                 /*
2456                  * Update buffer state, submit mapped pages, and get us new
2457                  * extent to map
2458                  */
2459                 err = mpage_map_and_submit_buffers(mpd);
2460                 if (err < 0)
2461                         goto update_disksize;
2462         } while (map->m_len);
2463 
2464 update_disksize:
2465         /*
2466          * Update on-disk size after IO is submitted.  Races with
2467          * truncate are avoided by checking i_size under i_data_sem.
2468          */
2469         disksize = ((loff_t)mpd->first_page) << PAGE_SHIFT;
2470         if (disksize > EXT4_I(inode)->i_disksize) {
2471                 int err2;
2472                 loff_t i_size;
2473 
2474                 down_write(&EXT4_I(inode)->i_data_sem);
2475                 i_size = i_size_read(inode);
2476                 if (disksize > i_size)
2477                         disksize = i_size;
2478                 if (disksize > EXT4_I(inode)->i_disksize)
2479                         EXT4_I(inode)->i_disksize = disksize;
2480                 err2 = ext4_mark_inode_dirty(handle, inode);
2481                 up_write(&EXT4_I(inode)->i_data_sem);
2482                 if (err2)
2483                         ext4_error(inode->i_sb,
2484                                    "Failed to mark inode %lu dirty",
2485                                    inode->i_ino);
2486                 if (!err)
2487                         err = err2;
2488         }
2489         return err;
2490 }
2491 
2492 /*
2493  * Calculate the total number of credits to reserve for one writepages
2494  * iteration. This is called from ext4_writepages(). We map an extent of
2495  * up to MAX_WRITEPAGES_EXTENT_LEN blocks and then we go on and finish mapping
2496  * the last partial page. So in total we can map MAX_WRITEPAGES_EXTENT_LEN +
2497  * bpp - 1 blocks in bpp different extents.
2498  */
2499 static int ext4_da_writepages_trans_blocks(struct inode *inode)
2500 {
2501         int bpp = ext4_journal_blocks_per_page(inode);
2502 
2503         return ext4_meta_trans_blocks(inode,
2504                                 MAX_WRITEPAGES_EXTENT_LEN + bpp - 1, bpp);
2505 }
2506 
2507 /*
2508  * mpage_prepare_extent_to_map - find & lock contiguous range of dirty pages
2509  *                               and underlying extent to map
2510  *
2511  * @mpd - where to look for pages
2512  *
2513  * Walk dirty pages in the mapping. If they are fully mapped, submit them for
2514  * IO immediately. When we find a page which isn't mapped we start accumulating
2515  * extent of buffers underlying these pages that needs mapping (formed by
2516  * either delayed or unwritten buffers). We also lock the pages containing
2517  * these buffers. The extent found is returned in @mpd structure (starting at
2518  * mpd->lblk with length mpd->len blocks).
2519  *
2520  * Note that this function can attach bios to one io_end structure which are
2521  * neither logically nor physically contiguous. Although it may seem as an
2522  * unnecessary complication, it is actually inevitable in blocksize < pagesize
2523  * case as we need to track IO to all buffers underlying a page in one io_end.
2524  */
2525 static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
2526 {
2527         struct address_space *mapping = mpd->inode->i_mapping;
2528         struct pagevec pvec;
2529         unsigned int nr_pages;
2530         long left = mpd->wbc->nr_to_write;
2531         pgoff_t index = mpd->first_page;
2532         pgoff_t end = mpd->last_page;
2533         int tag;
2534         int i, err = 0;
2535         int blkbits = mpd->inode->i_blkbits;
2536         ext4_lblk_t lblk;
2537         struct buffer_head *head;
2538 
2539         if (mpd->wbc->sync_mode == WB_SYNC_ALL || mpd->wbc->tagged_writepages)
2540                 tag = PAGECACHE_TAG_TOWRITE;
2541         else
2542                 tag = PAGECACHE_TAG_DIRTY;
2543 
2544         pagevec_init(&pvec, 0);
2545         mpd->map.m_len = 0;
2546         mpd->next_page = index;
2547         while (index <= end) {
2548                 nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
2549                               min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
2550                 if (nr_pages == 0)
2551                         goto out;
2552 
2553                 for (i = 0; i < nr_pages; i++) {
2554                         struct page *page = pvec.pages[i];
2555 
2556                         /*
2557                          * At this point, the page may be truncated or
2558                          * invalidated (changing page->mapping to NULL), or
2559                          * even swizzled back from swapper_space to tmpfs file
2560                          * mapping. However, page->index will not change
2561                          * because we have a reference on the page.
2562                          */
2563                         if (page->index > end)
2564                                 goto out;
2565 
2566                         /*
2567                          * Accumulated enough dirty pages? This doesn't apply
2568                          * to WB_SYNC_ALL mode. For integrity sync we have to
2569                          * keep going because someone may be concurrently
2570                          * dirtying pages, and we might have synced a lot of
2571                          * newly appeared dirty pages, but have not synced all
2572                          * of the old dirty pages.
2573                          */
2574                         if (mpd->wbc->sync_mode == WB_SYNC_NONE && left <= 0)
2575                                 goto out;
2576 
2577                         /* If we can't merge this page, we are done. */
2578                         if (mpd->map.m_len > 0 && mpd->next_page != page->index)
2579                                 goto out;
2580 
2581                         lock_page(page);
2582                         /*
2583                          * If the page is no longer dirty, or its mapping no
2584                          * longer corresponds to inode we are writing (which
2585                          * means it has been truncated or invalidated), or the
2586                          * page is already under writeback and we are not doing
2587                          * a data integrity writeback, skip the page
2588                          */
2589                         if (!PageDirty(page) ||
2590                             (PageWriteback(page) &&
2591                              (mpd->wbc->sync_mode == WB_SYNC_NONE)) ||
2592                             unlikely(page->mapping != mapping)) {
2593                                 unlock_page(page);
2594                                 continue;
2595                         }
2596 
2597                         wait_on_page_writeback(page);
2598                         BUG_ON(PageWriteback(page));
2599 
2600                         if (mpd->map.m_len == 0)
2601                                 mpd->first_page = page->index;
2602                         mpd->next_page = page->index + 1;
2603                         /* Add all dirty buffers to mpd */
2604                         lblk = ((ext4_lblk_t)page->index) <<
2605                                 (PAGE_SHIFT - blkbits);
2606                         head = page_buffers(page);
2607                         err = mpage_process_page_bufs(mpd, head, head, lblk);
2608                         if (err <= 0)
2609                                 goto out;
2610                         err = 0;
2611                         left--;
2612                 }
2613                 pagevec_release(&pvec);
2614                 cond_resched();
2615         }
2616         return 0;
2617 out:
2618         pagevec_release(&pvec);
2619         return err;
2620 }
2621 
2622 static int __writepage(struct page *page, struct writeback_control *wbc,
2623                        void *data)
2624 {
2625         struct address_space *mapping = data;
2626         int ret = ext4_writepage(page, wbc);
2627         mapping_set_error(mapping, ret);
2628         return ret;
2629 }
2630 
2631 static int ext4_writepages(struct address_space *mapping,
2632                            struct writeback_control *wbc)
2633 {
2634         pgoff_t writeback_index = 0;
2635         long nr_to_write = wbc->nr_to_write;
2636         int range_whole = 0;
2637         int cycled = 1;
2638         handle_t *handle = NULL;
2639         struct mpage_da_data mpd;
2640         struct inode *inode = mapping->host;
2641         int needed_blocks, rsv_blocks = 0, ret = 0;
2642         struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
2643         bool done;
2644         struct blk_plug plug;
2645         bool give_up_on_write = false;
2646 
2647         percpu_down_read(&sbi->s_journal_flag_rwsem);
2648         trace_ext4_writepages(inode, wbc);
2649 
2650         if (dax_mapping(mapping)) {
2651                 ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev,
2652                                                   wbc);
2653                 goto out_writepages;
2654         }
2655 
2656         /*
2657          * No pages to write? This is mainly a kludge to avoid starting
2658          * a transaction for special inodes like journal inode on last iput()
2659          * because that could violate lock ordering on umount
2660          */
2661         if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
2662                 goto out_writepages;
2663 
2664         if (ext4_should_journal_data(inode)) {
2665                 struct blk_plug plug;
2666 
2667                 blk_start_plug(&plug);
2668                 ret = write_cache_pages(mapping, wbc, __writepage, mapping);
2669                 blk_finish_plug(&plug);
2670                 goto out_writepages;
2671         }
2672 
2673         /*
2674          * If the filesystem has aborted, it is read-only, so return
2675          * right away instead of dumping stack traces later on that
2676          * will obscure the real source of the problem.  We test
2677          * EXT4_MF_FS_ABORTED instead of sb->s_flag's MS_RDONLY because
2678          * the latter could be true if the filesystem is mounted
2679          * read-only, and in that case, ext4_writepages should
2680          * *never* be called, so if that ever happens, we would want
2681          * the stack trace.
2682          */
2683         if (unlikely(sbi->s_mount_flags & EXT4_MF_FS_ABORTED)) {
2684                 ret = -EROFS;
2685                 goto out_writepages;
2686         }
2687 
2688         if (ext4_should_dioread_nolock(inode)) {
2689                 /*
2690                  * We may need to convert up to one extent per block in
2691                  * the page and we may dirty the inode.
2692                  */
2693                 rsv_blocks = 1 + (PAGE_SIZE >> inode->i_blkbits);
2694         }
2695 
2696         /*
2697          * If we have inline data and arrive here, it means that
2698          * we will soon create the block for the 1st page, so
2699          * we'd better clear the inline data here.
2700          */
2701         if (ext4_has_inline_data(inode)) {
2702                 /* Just inode will be modified... */
2703                 handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
2704                 if (IS_ERR(handle)) {
2705                         ret = PTR_ERR(handle);
2706                         goto out_writepages;
2707                 }
2708                 BUG_ON(ext4_test_inode_state(inode,
2709                                 EXT4_STATE_MAY_INLINE_DATA));
2710                 ext4_destroy_inline_data(handle, inode);
2711                 ext4_journal_stop(handle);
2712         }
2713 
2714         if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2715                 range_whole = 1;
2716 
2717         if (wbc->range_cyclic) {
2718                 writeback_index = mapping->writeback_index;
2719                 if (writeback_index)
2720                         cycled = 0;
2721                 mpd.first_page = writeback_index;
2722                 mpd.last_page = -1;
2723         } else {
2724                 mpd.first_page = wbc->range_start >> PAGE_SHIFT;
2725                 mpd.last_page = wbc->range_end >> PAGE_SHIFT;
2726         }
2727 
2728         mpd.inode = inode;
2729         mpd.wbc = wbc;
2730         ext4_io_submit_init(&mpd.io_submit, wbc);
2731 retry:
2732         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
2733                 tag_pages_for_writeback(mapping, mpd.first_page, mpd.last_page);
2734         done = false;
2735         blk_start_plug(&plug);
2736         while (!done && mpd.first_page <= mpd.last_page) {
2737                 /* For each extent of pages we use new io_end */
2738                 mpd.io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
2739                 if (!mpd.io_submit.io_end) {
2740                         ret = -ENOMEM;
2741                         break;
2742                 }
2743 
2744                 /*
2745                  * We have two constraints: We find one extent to map and we
2746                  * must always write out whole page (makes a difference when
2747                  * blocksize < pagesize) so that we don't block on IO when we
2748                  * try to write out the rest of the page. Journalled mode is
2749                  * not supported by delalloc.
2750                  */
2751                 BUG_ON(ext4_should_journal_data(inode));
2752                 needed_blocks = ext4_da_writepages_trans_blocks(inode);
2753 
2754                 /* start a new transaction */
2755                 handle = ext4_journal_start_with_reserve(inode,
2756                                 EXT4_HT_WRITE_PAGE, needed_blocks, rsv_blocks);
2757                 if (IS_ERR(handle)) {
2758                         ret = PTR_ERR(handle);
2759                         ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
2760                                "%ld pages, ino %lu; err %d", __func__,
2761                                 wbc->nr_to_write, inode->i_ino, ret);
2762                         /* Release allocated io_end */
2763                         ext4_put_io_end(mpd.io_submit.io_end);
2764                         break;
2765                 }
2766 
2767                 trace_ext4_da_write_pages(inode, mpd.first_page, mpd.wbc);
2768                 ret = mpage_prepare_extent_to_map(&mpd);
2769                 if (!ret) {
2770                         if (mpd.map.m_len)
2771                                 ret = mpage_map_and_submit_extent(handle, &mpd,
2772                                         &give_up_on_write);
2773                         else {
2774                                 /*
2775                                  * We scanned the whole range (or exhausted
2776                                  * nr_to_write), submitted what was mapped and
2777                                  * didn't find anything needing mapping. We are
2778                                  * done.
2779                                  */
2780                                 done = true;
2781                         }
2782                 }
2783                 /*
2784                  * Caution: If the handle is synchronous,
2785                  * ext4_journal_stop() can wait for transaction commit
2786                  * to finish which may depend on writeback of pages to
2787                  * complete or on page lock to be released.  In that
2788                  * case, we have to wait until after after we have
2789                  * submitted all the IO, released page locks we hold,
2790                  * and dropped io_end reference (for extent conversion
2791                  * to be able to complete) before stopping the handle.
2792                  */
2793                 if (!ext4_handle_valid(handle) || handle->h_sync == 0) {
2794                         ext4_journal_stop(handle);
2795                         handle = NULL;
2796                 }
2797                 /* Submit prepared bio */
2798                 ext4_io_submit(&mpd.io_submit);
2799                 /* Unlock pages we didn't use */
2800                 mpage_release_unused_pages(&mpd, give_up_on_write);
2801                 /*
2802                  * Drop our io_end reference we got from init. We have
2803                  * to be careful and use deferred io_end finishing if
2804                  * we are still holding the transaction as we can
2805                  * release the last reference to io_end which may end
2806                  * up doing unwritten extent conversion.
2807                  */
2808                 if (handle) {
2809                         ext4_put_io_end_defer(mpd.io_submit.io_end);
2810                         ext4_journal_stop(handle);
2811                 } else
2812                         ext4_put_io_end(mpd.io_submit.io_end);
2813 
2814                 if (ret == -ENOSPC && sbi->s_journal) {
2815                         /*
2816                          * Commit the transaction which would
2817                          * free blocks released in the transaction
2818                          * and try again
2819                          */
2820                         jbd2_journal_force_commit_nested(sbi->s_journal);
2821                         ret = 0;
2822                         continue;
2823                 }
2824                 /* Fatal error - ENOMEM, EIO... */
2825                 if (ret)
2826                         break;
2827         }
2828         blk_finish_plug(&plug);
2829         if (!ret && !cycled && wbc->nr_to_write > 0) {
2830                 cycled = 1;
2831                 mpd.last_page = writeback_index - 1;
2832                 mpd.first_page = 0;
2833                 goto retry;
2834         }
2835 
2836         /* Update index */
2837         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
2838                 /*
2839                  * Set the writeback_index so that range_cyclic
2840                  * mode will write it back later
2841                  */
2842                 mapping->writeback_index = mpd.first_page;
2843 
2844 out_writepages:
2845         trace_ext4_writepages_result(inode, wbc, ret,
2846                                      nr_to_write - wbc->nr_to_write);
2847         percpu_up_read(&sbi->s_journal_flag_rwsem);
2848         return ret;
2849 }
2850 
2851 static int ext4_nonda_switch(struct super_block *sb)
2852 {
2853         s64 free_clusters, dirty_clusters;
2854         struct ext4_sb_info *sbi = EXT4_SB(sb);
2855 
2856         /*
2857          * switch to non delalloc mode if we are running low
2858          * on free block. The free block accounting via percpu
2859          * counters can get slightly wrong with percpu_counter_batch getting
2860          * accumulated on each CPU without updating global counters
2861          * Delalloc need an accurate free block accounting. So switch
2862          * to non delalloc when we are near to error range.
2863          */
2864         free_clusters =
2865                 percpu_counter_read_positive(&sbi->s_freeclusters_counter);
2866         dirty_clusters =
2867                 percpu_counter_read_positive(&sbi->s_dirtyclusters_counter);
2868         /*
2869          * Start pushing delalloc when 1/2 of free blocks are dirty.
2870          */
2871         if (dirty_clusters && (free_clusters < 2 * dirty_clusters))
2872                 try_to_writeback_inodes_sb(sb, WB_REASON_FS_FREE_SPACE);
2873 
2874         if (2 * free_clusters < 3 * dirty_clusters ||
2875             free_clusters < (dirty_clusters + EXT4_FREECLUSTERS_WATERMARK)) {
2876                 /*
2877                  * free block count is less than 150% of dirty blocks
2878                  * or free blocks is less than watermark
2879                  */
2880                 return 1;
2881         }
2882         return 0;
2883 }
2884 
2885 /* We always reserve for an inode update; the superblock could be there too */
2886 static int ext4_da_write_credits(struct inode *inode, loff_t pos, unsigned len)
2887 {
2888         if (likely(ext4_has_feature_large_file(inode->i_sb)))
2889                 return 1;
2890 
2891         if (pos + len <= 0x7fffffffULL)
2892                 return 1;
2893 
2894         /* We might need to update the superblock to set LARGE_FILE */
2895         return 2;
2896 }
2897 
2898 static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
2899                                loff_t pos, unsigned len, unsigned flags,
2900                                struct page **pagep, void **fsdata)
2901 {
2902         int ret, retries = 0;
2903         struct page *page;
2904         pgoff_t index;
2905         struct inode *inode = mapping->host;
2906         handle_t *handle;
2907 
2908         index = pos >> PAGE_SHIFT;
2909 
2910         if (ext4_nonda_switch(inode->i_sb) ||
2911             S_ISLNK(inode->i_mode)) {
2912                 *fsdata = (void *)FALL_BACK_TO_NONDELALLOC;
2913                 return ext4_write_begin(file, mapping, pos,
2914                                         len, flags, pagep, fsdata);
2915         }
2916         *fsdata = (void *)0;
2917         trace_ext4_da_write_begin(inode, pos, len, flags);
2918 
2919         if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
2920                 ret = ext4_da_write_inline_data_begin(mapping, inode,
2921                                                       pos, len, flags,
2922                                                       pagep, fsdata);
2923                 if (ret < 0)
2924                         return ret;
2925                 if (ret == 1)
2926                         return 0;
2927         }
2928 
2929         /*
2930          * grab_cache_page_write_begin() can take a long time if the
2931          * system is thrashing due to memory pressure, or if the page
2932          * is being written back.  So grab it first before we start
2933          * the transaction handle.  This also allows us to allocate
2934          * the page (if needed) without using GFP_NOFS.
2935          */
2936 retry_grab:
2937         page = grab_cache_page_write_begin(mapping, index, flags);
2938         if (!page)
2939                 return -ENOMEM;
2940         unlock_page(page);
2941 
2942         /*
2943          * With delayed allocation, we don't log the i_disksize update
2944          * if there is delayed block allocation. But we still need
2945          * to journalling the i_disksize update if writes to the end
2946          * of file which has an already mapped buffer.
2947          */
2948 retry_journal:
2949         handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
2950                                 ext4_da_write_credits(inode, pos, len));
2951         if (IS_ERR(handle)) {
2952                 put_page(page);
2953                 return PTR_ERR(handle);
2954         }
2955 
2956         lock_page(page);
2957         if (page->mapping != mapping) {
2958                 /* The page got truncated from under us */
2959                 unlock_page(page);
2960                 put_page(page);
2961                 ext4_journal_stop(handle);
2962                 goto retry_grab;
2963         }
2964         /* In case writeback began while the page was unlocked */
2965         wait_for_stable_page(page);
2966 
2967 #ifdef CONFIG_EXT4_FS_ENCRYPTION
2968         ret = ext4_block_write_begin(page, pos, len,
2969                                      ext4_da_get_block_prep);
2970 #else
2971         ret = __block_write_begin(page, pos, len, ext4_da_get_block_prep);
2972 #endif
2973         if (ret < 0) {
2974                 unlock_page(page);
2975                 ext4_journal_stop(handle);
2976                 /*
2977                  * block_write_begin may have instantiated a few blocks
2978                  * outside i_size.  Trim these off again. Don't need
2979                  * i_size_read because we hold i_mutex.
2980                  */
2981                 if (pos + len > inode->i_size)
2982                         ext4_truncate_failed_write(inode);
2983 
2984                 if (ret == -ENOSPC &&
2985                     ext4_should_retry_alloc(inode->i_sb, &retries))
2986                         goto retry_journal;
2987 
2988                 put_page(page);
2989                 return ret;
2990         }
2991 
2992         *pagep = page;
2993         return ret;
2994 }
2995 
2996 /*
2997  * Check if we should update i_disksize
2998  * when write to the end of file but not require block allocation
2999  */
3000 static int ext4_da_should_update_i_disksize(struct page *page,
3001                                             unsigned long offset)
3002 {
3003         struct buffer_head *bh;
3004         struct inode *inode = page->mapping->host;
3005         unsigned int idx;
3006         int i;
3007 
3008         bh = page_buffers(page);
3009         idx = offset >> inode->i_blkbits;
3010 
3011         for (i = 0; i < idx; i++)
3012                 bh = bh->b_this_page;
3013 
3014         if (!buffer_mapped(bh) || (buffer_delay(bh)) || buffer_unwritten(bh))
3015                 return 0;
3016         return 1;
3017 }
3018 
3019 static int ext4_da_write_end(struct file *file,
3020                              struct address_space *mapping,
3021                              loff_t pos, unsigned len, unsigned copied,
3022                              struct page *page, void *fsdata)
3023 {
3024         struct inode *inode = mapping->host;
3025         int ret = 0, ret2;
3026         handle_t *handle = ext4_journal_current_handle();
3027         loff_t new_i_size;
3028         unsigned long start, end;
3029         int write_mode = (int)(unsigned long)fsdata;
3030 
3031         if (write_mode == FALL_BACK_TO_NONDELALLOC)
3032                 return ext4_write_end(file, mapping, pos,
3033                                       len, copied, page, fsdata);
3034 
3035         trace_ext4_da_write_end(inode, pos, len, copied);
3036         start = pos & (PAGE_SIZE - 1);
3037         end = start + copied - 1;
3038 
3039         /*
3040          * generic_write_end() will run mark_inode_dirty() if i_size
3041          * changes.  So let's piggyback the i_disksize mark_inode_dirty
3042          * into that.
3043          */
3044         new_i_size = pos + copied;
3045         if (copied && new_i_size > EXT4_I(inode)->i_disksize) {
3046                 if (ext4_has_inline_data(inode) ||
3047                     ext4_da_should_update_i_disksize(page, end)) {
3048                         ext4_update_i_disksize(inode, new_i_size);
3049                         /* We need to mark inode dirty even if
3050                          * new_i_size is less that inode->i_size
3051                          * bu greater than i_disksize.(hint delalloc)
3052                          */
3053                         ext4_mark_inode_dirty(handle, inode);
3054                 }
3055         }
3056 
3057         if (write_mode != CONVERT_INLINE_DATA &&
3058             ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) &&
3059             ext4_has_inline_data(inode))
3060                 ret2 = ext4_da_write_inline_data_end(inode, pos, len, copied,
3061                                                      page);
3062         else
3063                 ret2 = generic_write_end(file, mapping, pos, len, copied,
3064                                                         page, fsdata);
3065 
3066         copied = ret2;
3067         if (ret2 < 0)
3068                 ret = ret2;
3069         ret2 = ext4_journal_stop(handle);
3070         if (!ret)
3071                 ret = ret2;
3072 
3073         return ret ? ret : copied;
3074 }
3075 
3076 static void ext4_da_invalidatepage(struct page *page, unsigned int offset,
3077                                    unsigned int length)
3078 {
3079         /*
3080          * Drop reserved blocks
3081          */
3082         BUG_ON(!PageLocked(page));
3083         if (!page_has_buffers(page))
3084                 goto out;
3085 
3086         ext4_da_page_release_reservation(page, offset, length);
3087 
3088 out:
3089         ext4_invalidatepage(page, offset, length);
3090 
3091         return;
3092 }
3093 
3094 /*
3095  * Force all delayed allocation blocks to be allocated for a given inode.
3096  */
3097 int ext4_alloc_da_blocks(struct inode *inode)
3098 {
3099         trace_ext4_alloc_da_blocks(inode);
3100 
3101         if (!EXT4_I(inode)->i_reserved_data_blocks)
3102                 return 0;
3103 
3104         /*
3105          * We do something simple for now.  The filemap_flush() will
3106          * also start triggering a write of the data blocks, which is
3107          * not strictly speaking necessary (and for users of
3108          * laptop_mode, not even desirable).  However, to do otherwise
3109          * would require replicating code paths in:
3110          *
3111          * ext4_writepages() ->
3112          *    write_cache_pages() ---> (via passed in callback function)
3113          *        __mpage_da_writepage() -->
3114          *           mpage_add_bh_to_extent()
3115          *           mpage_da_map_blocks()
3116          *
3117          * The problem is that write_cache_pages(), located in
3118          * mm/page-writeback.c, marks pages clean in preparation for
3119          * doing I/O, which is not desirable if we're not planning on
3120          * doing I/O at all.
3121          *
3122          * We could call write_cache_pages(), and then redirty all of
3123          * the pages by calling redirty_page_for_writepage() but that
3124          * would be ugly in the extreme.  So instead we would need to
3125          * replicate parts of the code in the above functions,
3126          * simplifying them because we wouldn't actually intend to
3127          * write out the pages, but rather only collect contiguous
3128          * logical block extents, call the multi-block allocator, and
3129          * then update the buffer heads with the block allocations.
3130          *
3131          * For now, though, we'll cheat by calling filemap_flush(),
3132          * which will map the blocks, and start the I/O, but not
3133          * actually wait for the I/O to complete.
3134          */
3135         return filemap_flush(inode->i_mapping);
3136 }
3137 
3138 /*
3139  * bmap() is special.  It gets used by applications such as lilo and by
3140  * the swapper to find the on-disk block of a specific piece of data.
3141  *
3142  * Naturally, this is dangerous if the block concerned is still in the
3143  * journal.  If somebody makes a swapfile on an ext4 data-journaling
3144  * filesystem and enables swap, then they may get a nasty shock when the
3145  * data getting swapped to that swapfile suddenly gets overwritten by
3146  * the original zero's written out previously to the journal and
3147  * awaiting writeback in the kernel's buffer cache.
3148  *
3149  * So, if we see any bmap calls here on a modified, data-journaled file,
3150  * take extra steps to flush any blocks which might be in the cache.
3151  */
3152 static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
3153 {
3154         struct inode *inode = mapping->host;
3155         journal_t *journal;
3156         int err;
3157 
3158         /*
3159          * We can get here for an inline file via the FIBMAP ioctl
3160          */
3161         if (ext4_has_inline_data(inode))
3162                 return 0;
3163 
3164         if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
3165                         test_opt(inode->i_sb, DELALLOC)) {
3166                 /*
3167                  * With delalloc we want to sync the file
3168                  * so that we can make sure we allocate
3169                  * blocks for file
3170                  */
3171                 filemap_write_and_wait(mapping);
3172         }
3173 
3174         if (EXT4_JOURNAL(inode) &&
3175             ext4_test_inode_state(inode, EXT4_STATE_JDATA)) {
3176                 /*
3177                  * This is a REALLY heavyweight approach, but the use of
3178                  * bmap on dirty files is expected to be extremely rare:
3179                  * only if we run lilo or swapon on a freshly made file
3180                  * do we expect this to happen.
3181                  *
3182                  * (bmap requires CAP_SYS_RAWIO so this does not
3183                  * represent an unprivileged user DOS attack --- we'd be
3184                  * in trouble if mortal users could trigger this path at
3185                  * will.)
3186                  *
3187                  * NB. EXT4_STATE_JDATA is not set on files other than
3188                  * regular files.  If somebody wants to bmap a directory
3189                  * or symlink and gets confused because the buffer
3190                  * hasn't yet been flushed to disk, they deserve
3191                  * everything they get.
3192                  */
3193 
3194                 ext4_clear_inode_state(inode, EXT4_STATE_JDATA);
3195                 journal = EXT4_JOURNAL(inode);
3196                 jbd2_journal_lock_updates(journal);
3197                 err = jbd2_journal_flush(journal);
3198                 jbd2_journal_unlock_updates(journal);
3199 
3200                 if (err)
3201                         return 0;
3202         }
3203 
3204         return generic_block_bmap(mapping, block, ext4_get_block);
3205 }
3206 
3207 static int ext4_readpage(struct file *file, struct page *page)
3208 {
3209         int ret = -EAGAIN;
3210         struct inode *inode = page->mapping->host;
3211 
3212         trace_ext4_readpage(page);
3213 
3214         if (ext4_has_inline_data(inode))
3215                 ret = ext4_readpage_inline(inode, page);
3216 
3217         if (ret == -EAGAIN)
3218                 return ext4_mpage_readpages(page->mapping, NULL, page, 1);
3219 
3220         return ret;
3221 }
3222 
3223 static int
3224 ext4_readpages(struct file *file, struct address_space *mapping,
3225                 struct list_head *pages, unsigned nr_pages)
3226 {
3227         struct inode *inode = mapping->host;
3228 
3229         /* If the file has inline data, no need to do readpages. */
3230         if (ext4_has_inline_data(inode))
3231                 return 0;
3232 
3233         return ext4_mpage_readpages(mapping, pages, NULL, nr_pages);
3234 }
3235 
3236 static void ext4_invalidatepage(struct page *page, unsigned int offset,
3237                                 unsigned int length)
3238 {
3239         trace_ext4_invalidatepage(page, offset, length);
3240 
3241         /* No journalling happens on data buffers when this function is used */
3242         WARN_ON(page_has_buffers(page) && buffer_jbd(page_buffers(page)));
3243 
3244         block_invalidatepage(page, offset, length);
3245 }
3246 
3247 static int __ext4_journalled_invalidatepage(struct page *page,
3248                                             unsigned int offset,
3249                                             unsigned int length)
3250 {
3251         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
3252 
3253         trace_ext4_journalled_invalidatepage(page, offset, length);
3254 
3255         /*
3256          * If it's a full truncate we just forget about the pending dirtying
3257          */
3258         if (offset == 0 && length == PAGE_SIZE)
3259                 ClearPageChecked(page);
3260 
3261         return jbd2_journal_invalidatepage(journal, page, offset, length);
3262 }
3263 
3264 /* Wrapper for aops... */
3265 static void ext4_journalled_invalidatepage(struct page *page,
3266                                            unsigned int offset,
3267                                            unsigned int length)
3268 {
3269         WARN_ON(__ext4_journalled_invalidatepage(page, offset, length) < 0);
3270 }
3271 
3272 static int ext4_releasepage(struct page *page, gfp_t wait)
3273 {
3274         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
3275 
3276         trace_ext4_releasepage(page);
3277 
3278         /* Page has dirty journalled data -> cannot release */
3279         if (PageChecked(page))
3280                 return 0;
3281         if (journal)
3282                 return jbd2_journal_try_to_free_buffers(journal, page, wait);
3283         else
3284                 return try_to_free_buffers(page);
3285 }
3286 
3287 #ifdef CONFIG_FS_DAX
3288 static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
3289                             unsigned flags, struct iomap *iomap)
3290 {
3291         unsigned int blkbits = inode->i_blkbits;
3292         unsigned long first_block = offset >> blkbits;
3293         unsigned long last_block = (offset + length - 1) >> blkbits;
3294         struct ext4_map_blocks map;
3295         int ret;
3296 
3297         if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
3298                 return -ERANGE;
3299 
3300         map.m_lblk = first_block;
3301         map.m_len = last_block - first_block + 1;
3302 
3303         if (!(flags & IOMAP_WRITE)) {
3304                 ret = ext4_map_blocks(NULL, inode, &map, 0);
3305         } else {
3306                 int dio_credits;
3307                 handle_t *handle;
3308                 int retries = 0;
3309 
3310                 /* Trim mapping request to maximum we can map at once for DIO */
3311                 if (map.m_len > DIO_MAX_BLOCKS)
3312                         map.m_len = DIO_MAX_BLOCKS;
3313                 dio_credits = ext4_chunk_trans_blocks(inode, map.m_len);
3314 retry:
3315                 /*
3316                  * Either we allocate blocks and then we don't get unwritten
3317                  * extent so we have reserved enough credits, or the blocks
3318                  * are already allocated and unwritten and in that case
3319                  * extent conversion fits in the credits as well.
3320                  */
3321                 handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS,
3322                                             dio_credits);
3323                 if (IS_ERR(handle))
3324                         return PTR_ERR(handle);
3325 
3326                 ret = ext4_map_blocks(handle, inode, &map,
3327                                       EXT4_GET_BLOCKS_CREATE_ZERO);
3328                 if (ret < 0) {
3329                         ext4_journal_stop(handle);
3330                         if (ret == -ENOSPC &&
3331                             ext4_should_retry_alloc(inode->i_sb, &retries))
3332                                 goto retry;
3333                         return ret;
3334                 }
3335 
3336                 /*
3337                  * If we added blocks beyond i_size, we need to make sure they
3338                  * will get truncated if we crash before updating i_size in
3339                  * ext4_iomap_end(). For faults we don't need to do that (and
3340                  * even cannot because for orphan list operations inode_lock is
3341                  * required) - if we happen to instantiate block beyond i_size,
3342                  * it is because we race with truncate which has already added
3343                  * the inode to the orphan list.
3344                  */
3345                 if (!(flags & IOMAP_FAULT) && first_block + map.m_len >
3346                     (i_size_read(inode) + (1 << blkbits) - 1) >> blkbits) {
3347                         int err;
3348 
3349                         err = ext4_orphan_add(handle, inode);
3350                         if (err < 0) {
3351                                 ext4_journal_stop(handle);
3352                                 return err;
3353                         }
3354                 }
3355                 ext4_journal_stop(handle);
3356         }
3357 
3358         iomap->flags = 0;
3359         iomap->bdev = inode->i_sb->s_bdev;
3360         iomap->offset = first_block << blkbits;
3361 
3362         if (ret == 0) {
3363                 iomap->type = IOMAP_HOLE;
3364                 iomap->blkno = IOMAP_NULL_BLOCK;
3365                 iomap->length = (u64)map.m_len << blkbits;
3366         } else {
3367                 if (map.m_flags & EXT4_MAP_MAPPED) {
3368                         iomap->type = IOMAP_MAPPED;
3369                 } else if (map.m_flags & EXT4_MAP_UNWRITTEN) {
3370                         iomap->type = IOMAP_UNWRITTEN;
3371                 } else {
3372                         WARN_ON_ONCE(1);
3373                         return -EIO;
3374                 }
3375                 iomap->blkno = (sector_t)map.m_pblk << (blkbits - 9);
3376                 iomap->length = (u64)map.m_len << blkbits;
3377         }
3378 
3379         if (map.m_flags & EXT4_MAP_NEW)
3380                 iomap->flags |= IOMAP_F_NEW;
3381         return 0;
3382 }
3383 
3384 static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length,
3385                           ssize_t written, unsigned flags, struct iomap *iomap)
3386 {
3387         int ret = 0;
3388         handle_t *handle;
3389         int blkbits = inode->i_blkbits;
3390         bool truncate = false;
3391 
3392         if (!(flags & IOMAP_WRITE) || (flags & IOMAP_FAULT))
3393                 return 0;
3394 
3395         handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
3396         if (IS_ERR(handle)) {
3397                 ret = PTR_ERR(handle);
3398                 goto orphan_del;
3399         }
3400         if (ext4_update_inode_size(inode, offset + written))
3401                 ext4_mark_inode_dirty(handle, inode);
3402         /*
3403          * We may need to truncate allocated but not written blocks beyond EOF.
3404          */
3405         if (iomap->offset + iomap->length > 
3406             ALIGN(inode->i_size, 1 << blkbits)) {
3407                 ext4_lblk_t written_blk, end_blk;
3408 
3409                 written_blk = (offset + written) >> blkbits;
3410                 end_blk = (offset + length) >> blkbits;
3411                 if (written_blk < end_blk && ext4_can_truncate(inode))
3412                         truncate = true;
3413         }
3414         /*
3415          * Remove inode from orphan list if we were extending a inode and
3416          * everything went fine.
3417          */
3418         if (!truncate && inode->i_nlink &&
3419             !list_empty(&EXT4_I(inode)->i_orphan))
3420                 ext4_orphan_del(handle, inode);
3421         ext4_journal_stop(handle);
3422         if (truncate) {
3423                 ext4_truncate_failed_write(inode);
3424 orphan_del:
3425                 /*
3426                  * If truncate failed early the inode might still be on the
3427                  * orphan list; we need to make sure the inode is removed from
3428                  * the orphan list in that case.
3429                  */
3430                 if (inode->i_nlink)
3431                         ext4_orphan_del(NULL, inode);
3432         }
3433         return ret;
3434 }
3435 
3436 struct iomap_ops ext4_iomap_ops = {
3437         .iomap_begin            = ext4_iomap_begin,
3438         .iomap_end              = ext4_iomap_end,
3439 };
3440 
3441 #endif
3442 
3443 static int ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
3444                             ssize_t size, void *private)
3445 {
3446         ext4_io_end_t *io_end = private;
3447 
3448         /* if not async direct IO just return */
3449         if (!io_end)
3450                 return 0;
3451 
3452         ext_debug("ext4_end_io_dio(): io_end 0x%p "
3453                   "for inode %lu, iocb 0x%p, offset %llu, size %zd\n",
3454                   io_end, io_end->inode->i_ino, iocb, offset, size);
3455 
3456         /*
3457          * Error during AIO DIO. We cannot convert unwritten extents as the
3458          * data was not written. Just clear the unwritten flag and drop io_end.
3459          */
3460         if (size <= 0) {
3461                 ext4_clear_io_unwritten_flag(io_end);
3462                 size = 0;
3463         }
3464         io_end->offset = offset;
3465         io_end->size = size;
3466         ext4_put_io_end(io_end);
3467 
3468         return 0;
3469 }
3470 
3471 /*
3472  * Handling of direct IO writes.
3473  *
3474  * For ext4 extent files, ext4 will do direct-io write even to holes,
3475  * preallocated extents, and those write extend the file, no need to
3476  * fall back to buffered IO.
3477  *
3478  * For holes, we fallocate those blocks, mark them as unwritten
3479  * If those blocks were preallocated, we mark sure they are split, but
3480  * still keep the range to write as unwritten.
3481  *
3482  * The unwritten extents will be converted to written when DIO is completed.
3483  * For async direct IO, since the IO may still pending when return, we
3484  * set up an end_io call back function, which will do the conversion
3485  * when async direct IO completed.
3486  *
3487  * If the O_DIRECT write will extend the file then add this inode to the
3488  * orphan list.  So recovery will truncate it back to the original size
3489  * if the machine crashes during the write.
3490  *
3491  */
3492 static ssize_t ext4_direct_IO_write(struct kiocb *iocb, struct iov_iter *iter)
3493 {
3494         struct file *file = iocb->ki_filp;
3495         struct inode *inode = file->f_mapping->host;
3496         struct ext4_inode_info *ei = EXT4_I(inode);
3497         ssize_t ret;
3498         loff_t offset = iocb->ki_pos;
3499         size_t count = iov_iter_count(iter);
3500         int overwrite = 0;
3501         get_block_t *get_block_func = NULL;
3502         int dio_flags = 0;
3503         loff_t final_size = offset + count;
3504         int orphan = 0;
3505         handle_t *handle;
3506 
3507         if (final_size > inode->i_size) {
3508                 /* Credits for sb + inode write */
3509                 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
3510                 if (IS_ERR(handle)) {
3511                         ret = PTR_ERR(handle);
3512                         goto out;
3513                 }
3514                 ret = ext4_orphan_add(handle, inode);
3515                 if (ret) {
3516                         ext4_journal_stop(handle);
3517                         goto out;
3518                 }
3519                 orphan = 1;
3520                 ei->i_disksize = inode->i_size;
3521                 ext4_journal_stop(handle);
3522         }
3523 
3524         BUG_ON(iocb->private == NULL);
3525 
3526         /*
3527          * Make all waiters for direct IO properly wait also for extent
3528          * conversion. This also disallows race between truncate() and
3529          * overwrite DIO as i_dio_count needs to be incremented under i_mutex.
3530          */
3531         inode_dio_begin(inode);
3532 
3533         /* If we do a overwrite dio, i_mutex locking can be released */
3534         overwrite = *((int *)iocb->private);
3535 
3536         if (overwrite)
3537                 inode_unlock(inode);
3538 
3539         /*
3540          * For extent mapped files we could direct write to holes and fallocate.
3541          *
3542          * Allocated blocks to fill the hole are marked as unwritten to prevent
3543          * parallel buffered read to expose the stale data before DIO complete
3544          * the data IO.
3545          *
3546          * As to previously fallocated extents, ext4 get_block will just simply
3547          * mark the buffer mapped but still keep the extents unwritten.
3548          *
3549          * For non AIO case, we will convert those unwritten extents to written
3550          * after return back from blockdev_direct_IO. That way we save us from
3551          * allocating io_end structure and also the overhead of offloading
3552          * the extent convertion to a workqueue.
3553          *
3554          * For async DIO, the conversion needs to be deferred when the
3555          * IO is completed. The ext4 end_io callback function will be
3556          * called to take care of the conversion work.  Here for async
3557          * case, we allocate an io_end structure to hook to the iocb.
3558          */
3559         iocb->private = NULL;
3560         if (overwrite)
3561                 get_block_func = ext4_dio_get_block_overwrite;
3562         else if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) ||
3563                    round_down(offset, 1 << inode->i_blkbits) >= inode->i_size) {
3564                 get_block_func = ext4_dio_get_block;
3565                 dio_flags = DIO_LOCKING | DIO_SKIP_HOLES;
3566         } else if (is_sync_kiocb(iocb)) {
3567                 get_block_func = ext4_dio_get_block_unwritten_sync;
3568                 dio_flags = DIO_LOCKING;
3569         } else {
3570                 get_block_func = ext4_dio_get_block_unwritten_async;
3571                 dio_flags = DIO_LOCKING;
3572         }
3573 #ifdef CONFIG_EXT4_FS_ENCRYPTION
3574         BUG_ON(ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode));
3575 #endif
3576         ret = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
3577                                    get_block_func, ext4_end_io_dio, NULL,
3578                                    dio_flags);
3579 
3580         if (ret > 0 && !overwrite && ext4_test_inode_state(inode,
3581                                                 EXT4_STATE_DIO_UNWRITTEN)) {
3582                 int err;
3583                 /*
3584                  * for non AIO case, since the IO is already
3585                  * completed, we could do the conversion right here
3586                  */
3587                 err = ext4_convert_unwritten_extents(NULL, inode,
3588                                                      offset, ret);
3589                 if (err < 0)
3590                         ret = err;
3591                 ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
3592         }
3593 
3594         inode_dio_end(inode);
3595         /* take i_mutex locking again if we do a ovewrite dio */
3596         if (overwrite)
3597                 inode_lock(inode);
3598 
3599         if (ret < 0 && final_size > inode->i_size)
3600                 ext4_truncate_failed_write(inode);
3601 
3602         /* Handle extending of i_size after direct IO write */
3603         if (orphan) {
3604                 int err;
3605 
3606                 /* Credits for sb + inode write */
3607                 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
3608                 if (IS_ERR(handle)) {
3609                         /* This is really bad luck. We've written the data
3610                          * but cannot extend i_size. Bail out and pretend
3611                          * the write failed... */
3612                         ret = PTR_ERR(handle);
3613                         if (inode->i_nlink)
3614                                 ext4_orphan_del(NULL, inode);
3615 
3616                         goto out;
3617                 }
3618                 if (inode->i_nlink)
3619                         ext4_orphan_del(handle, inode);
3620                 if (ret > 0) {
3621                         loff_t end = offset + ret;
3622                         if (end > inode->i_size) {
3623                                 ei->i_disksize = end;
3624                                 i_size_write(inode, end);
3625                                 /*
3626                                  * We're going to return a positive `ret'
3627                                  * here due to non-zero-length I/O, so there's
3628                                  * no way of reporting error returns from
3629                                  * ext4_mark_inode_dirty() to userspace.  So
3630                                  * ignore it.
3631                                  */
3632                                 ext4_mark_inode_dirty(handle, inode);
3633                         }
3634                 }
3635                 err = ext4_journal_stop(handle);
3636                 if (ret == 0)
3637                         ret = err;
3638         }
3639 out:
3640         return ret;
3641 }
3642 
3643 static ssize_t ext4_direct_IO_read(struct kiocb *iocb, struct iov_iter *iter)
3644 {
3645         struct address_space *mapping = iocb->ki_filp->f_mapping;
3646         struct inode *inode = mapping->host;
3647         size_t count = iov_iter_count(iter);
3648         ssize_t ret;
3649 
3650         /*
3651          * Shared inode_lock is enough for us - it protects against concurrent
3652          * writes & truncates and since we take care of writing back page cache,
3653          * we are protected against page writeback as well.
3654          */
3655         inode_lock_shared(inode);
3656         ret = filemap_write_and_wait_range(mapping, iocb->ki_pos,
3657                                            iocb->ki_pos + count);
3658         if (ret)
3659                 goto out_unlock;
3660         ret = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev,
3661                                    iter, ext4_dio_get_block, NULL, NULL, 0);
3662 out_unlock:
3663         inode_unlock_shared(inode);
3664         return ret;
3665 }
3666 
3667 static ssize_t ext4_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
3668 {
3669         struct file *file = iocb->ki_filp;
3670         struct inode *inode = file->f_mapping->host;
3671         size_t count = iov_iter_count(iter);
3672         loff_t offset = iocb->ki_pos;
3673         ssize_t ret;
3674 
3675 #ifdef CONFIG_EXT4_FS_ENCRYPTION
3676         if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode))
3677                 return 0;
3678 #endif
3679 
3680         /*
3681          * If we are doing data journalling we don't support O_DIRECT
3682          */
3683         if (ext4_should_journal_data(inode))
3684                 return 0;
3685 
3686         /* Let buffer I/O handle the inline data case. */
3687         if (ext4_has_inline_data(inode))
3688                 return 0;
3689 
3690         /* DAX uses iomap path now */
3691         if (WARN_ON_ONCE(IS_DAX(inode)))
3692                 return 0;
3693 
3694         trace_ext4_direct_IO_enter(inode, offset, count, iov_iter_rw(iter));
3695         if (iov_iter_rw(iter) == READ)
3696                 ret = ext4_direct_IO_read(iocb, iter);
3697         else
3698                 ret = ext4_direct_IO_write(iocb, iter);
3699         trace_ext4_direct_IO_exit(inode, offset, count, iov_iter_rw(iter), ret);
3700         return ret;
3701 }
3702 
3703 /*
3704  * Pages can be marked dirty completely asynchronously from ext4's journalling
3705  * activity.  By filemap_sync_pte(), try_to_unmap_one(), etc.  We cannot do
3706  * much here because ->set_page_dirty is called under VFS locks.  The page is
3707  * not necessarily locked.
3708  *
3709  * We cannot just dirty the page and leave attached buffers clean, because the
3710  * buffers' dirty state is "definitive".  We cannot just set the buffers dirty
3711  * or jbddirty because all the journalling code will explode.
3712  *
3713  * So what we do is to mark the page "pending dirty" and next time writepage
3714  * is called, propagate that into the buffers appropriately.
3715  */
3716 static int ext4_journalled_set_page_dirty(struct page *page)
3717 {
3718         SetPageChecked(page);
3719         return __set_page_dirty_nobuffers(page);
3720 }
3721 
3722 static int ext4_set_page_dirty(struct page *page)
3723 {
3724         WARN_ON_ONCE(!PageLocked(page) && !PageDirty(page));
3725         WARN_ON_ONCE(!page_has_buffers(page));
3726         return __set_page_dirty_buffers(page);
3727 }
3728 
3729 static const struct address_space_operations ext4_aops = {
3730         .readpage               = ext4_readpage,
3731         .readpages              = ext4_readpages,
3732         .writepage              = ext4_writepage,
3733         .writepages             = ext4_writepages,
3734         .write_begin            = ext4_write_begin,
3735         .write_end              = ext4_write_end,
3736         .set_page_dirty         = ext4_set_page_dirty,
3737         .bmap                   = ext4_bmap,
3738         .invalidatepage         = ext4_invalidatepage,
3739         .releasepage            = ext4_releasepage,
3740         .direct_IO              = ext4_direct_IO,
3741         .migratepage            = buffer_migrate_page,
3742         .is_partially_uptodate  = block_is_partially_uptodate,
3743         .error_remove_page      = generic_error_remove_page,
3744 };
3745 
3746 static const struct address_space_operations ext4_journalled_aops = {
3747         .readpage               = ext4_readpage,
3748         .readpages              = ext4_readpages,
3749         .writepage              = ext4_writepage,
3750         .writepages             = ext4_writepages,
3751         .write_begin            = ext4_write_begin,
3752         .write_end              = ext4_journalled_write_end,
3753         .set_page_dirty         = ext4_journalled_set_page_dirty,
3754         .bmap                   = ext4_bmap,
3755         .invalidatepage         = ext4_journalled_invalidatepage,
3756         .releasepage            = ext4_releasepage,
3757         .direct_IO              = ext4_direct_IO,
3758         .is_partially_uptodate  = block_is_partially_uptodate,
3759         .error_remove_page      = generic_error_remove_page,
3760 };
3761 
3762 static const struct address_space_operations ext4_da_aops = {
3763         .readpage               = ext4_readpage,
3764         .readpages              = ext4_readpages,
3765         .writepage              = ext4_writepage,
3766         .writepages             = ext4_writepages,
3767         .write_begin            = ext4_da_write_begin,
3768         .write_end              = ext4_da_write_end,
3769         .set_page_dirty         = ext4_set_page_dirty,
3770         .bmap                   = ext4_bmap,
3771         .invalidatepage         = ext4_da_invalidatepage,
3772         .releasepage            = ext4_releasepage,
3773         .direct_IO              = ext4_direct_IO,
3774         .migratepage            = buffer_migrate_page,
3775         .is_partially_uptodate  = block_is_partially_uptodate,
3776         .error_remove_page      = generic_error_remove_page,
3777 };
3778 
3779 void ext4_set_aops(struct inode *inode)
3780 {
3781         switch (ext4_inode_journal_mode(inode)) {
3782         case EXT4_INODE_ORDERED_DATA_MODE:
3783         case EXT4_INODE_WRITEBACK_DATA_MODE:
3784                 break;
3785         case EXT4_INODE_JOURNAL_DATA_MODE:
3786                 inode->i_mapping->a_ops = &ext4_journalled_aops;
3787                 return;
3788         default:
3789                 BUG();
3790         }
3791         if (test_opt(inode->i_sb, DELALLOC))
3792                 inode->i_mapping->a_ops = &ext4_da_aops;
3793         else
3794                 inode->i_mapping->a_ops = &ext4_aops;
3795 }
3796 
3797 static int __ext4_block_zero_page_range(handle_t *handle,
3798                 struct address_space *mapping, loff_t from, loff_t length)
3799 {
3800         ext4_fsblk_t index = from >> PAGE_SHIFT;
3801         unsigned offset = from & (PAGE_SIZE-1);
3802         unsigned blocksize, pos;
3803         ext4_lblk_t iblock;
3804         struct inode *inode = mapping->host;
3805         struct buffer_head *bh;
3806         struct page *page;
3807         int err = 0;
3808 
3809         page = find_or_create_page(mapping, from >> PAGE_SHIFT,
3810                                    mapping_gfp_constraint(mapping, ~__GFP_FS));
3811         if (!page)
3812                 return -ENOMEM;
3813 
3814         blocksize = inode->i_sb->s_blocksize;
3815 
3816         iblock = index << (PAGE_SHIFT - inode->i_sb->s_blocksize_bits);
3817 
3818         if (!page_has_buffers(page))
3819                 create_empty_buffers(page, blocksize, 0);
3820 
3821         /* Find the buffer that contains "offset" */
3822         bh = page_buffers(page);
3823         pos = blocksize;
3824         while (offset >= pos) {
3825                 bh = bh->b_this_page;
3826                 iblock++;
3827                 pos += blocksize;
3828         }
3829         if (buffer_freed(bh)) {
3830                 BUFFER_TRACE(bh, "freed: skip");
3831                 goto unlock;
3832         }
3833         if (!buffer_mapped(bh)) {
3834                 BUFFER_TRACE(bh, "unmapped");
3835                 ext4_get_block(inode, iblock, bh, 0);
3836                 /* unmapped? It's a hole - nothing to do */
3837                 if (!buffer_mapped(bh)) {
3838                         BUFFER_TRACE(bh, "still unmapped");
3839                         goto unlock;
3840                 }
3841         }
3842 
3843         /* Ok, it's mapped. Make sure it's up-to-date */
3844         if (PageUptodate(page))
3845                 set_buffer_uptodate(bh);
3846 
3847         if (!buffer_uptodate(bh)) {
3848                 err = -EIO;
3849                 ll_rw_block(REQ_OP_READ, 0, 1, &bh);
3850                 wait_on_buffer(bh);
3851                 /* Uhhuh. Read error. Complain and punt. */
3852                 if (!buffer_uptodate(bh))
3853                         goto unlock;
3854                 if (S_ISREG(inode->i_mode) &&
3855                     ext4_encrypted_inode(inode)) {
3856                         /* We expect the key to be set. */
3857                         BUG_ON(!fscrypt_has_encryption_key(inode));
3858                         BUG_ON(blocksize != PAGE_SIZE);
3859                         WARN_ON_ONCE(fscrypt_decrypt_page(page->mapping->host,
3860                                                 page, PAGE_SIZE, 0, page->index));
3861                 }
3862         }
3863         if (ext4_should_journal_data(inode)) {
3864                 BUFFER_TRACE(bh, "get write access");
3865                 err = ext4_journal_get_write_access(handle, bh);
3866                 if (err)
3867                         goto unlock;
3868         }
3869         zero_user(page, offset, length);
3870         BUFFER_TRACE(bh, "zeroed end of block");
3871 
3872         if (ext4_should_journal_data(inode)) {
3873                 err = ext4_handle_dirty_metadata(handle, inode, bh);
3874         } else {
3875                 err = 0;
3876                 mark_buffer_dirty(bh);
3877                 if (ext4_should_order_data(inode))
3878                         err = ext4_jbd2_inode_add_write(handle, inode);
3879         }
3880 
3881 unlock:
3882         unlock_page(page);
3883         put_page(page);
3884         return err;
3885 }
3886 
3887 /*
3888  * ext4_block_zero_page_range() zeros out a mapping of length 'length'
3889  * starting from file offset 'from'.  The range to be zero'd must
3890  * be contained with in one block.  If the specified range exceeds
3891  * the end of the block it will be shortened to end of the block
3892  * that cooresponds to 'from'
3893  */
3894 static int ext4_block_zero_page_range(handle_t *handle,
3895                 struct address_space *mapping, loff_t from, loff_t length)
3896 {
3897         struct inode *inode = mapping->host;
3898         unsigned offset = from & (PAGE_SIZE-1);
3899         unsigned blocksize = inode->i_sb->s_blocksize;
3900         unsigned max = blocksize - (offset & (blocksize - 1));
3901 
3902         /*
3903          * correct length if it does not fall between
3904          * 'from' and the end of the block
3905          */
3906         if (length > max || length < 0)
3907                 length = max;
3908 
3909         if (IS_DAX(inode)) {
3910                 return iomap_zero_range(inode, from, length, NULL,
3911                                         &ext4_iomap_ops);
3912         }
3913         return __ext4_block_zero_page_range(handle, mapping, from, length);
3914 }
3915 
3916 /*
3917  * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
3918  * up to the end of the block which corresponds to `from'.
3919  * This required during truncate. We need to physically zero the tail end
3920  * of that block so it doesn't yield old data if the file is later grown.
3921  */
3922 static int ext4_block_truncate_page(handle_t *handle,
3923                 struct address_space *mapping, loff_t from)
3924 {
3925         unsigned offset = from & (PAGE_SIZE-1);
3926         unsigned length;
3927         unsigned blocksize;
3928         struct inode *inode = mapping->host;
3929 
3930         /* If we are processing an encrypted inode during orphan list handling */
3931         if (ext4_encrypted_inode(inode) && !fscrypt_has_encryption_key(inode))
3932                 return 0;
3933 
3934         blocksize = inode->i_sb->s_blocksize;
3935         length = blocksize - (offset & (blocksize - 1));
3936 
3937         return ext4_block_zero_page_range(handle, mapping, from, length);
3938 }
3939 
3940 int ext4_zero_partial_blocks(handle_t *handle, struct inode *inode,
3941                              loff_t lstart, loff_t length)
3942 {
3943         struct super_block *sb = inode->i_sb;
3944         struct address_space *mapping = inode->i_mapping;
3945         unsigned partial_start, partial_end;
3946         ext4_fsblk_t start, end;
3947         loff_t byte_end = (lstart + length - 1);
3948         int err = 0;
3949 
3950         partial_start = lstart & (sb->s_blocksize - 1);
3951         partial_end = byte_end & (sb->s_blocksize - 1);
3952 
3953         start = lstart >> sb->s_blocksize_bits;
3954         end = byte_end >> sb->s_blocksize_bits;
3955 
3956         /* Handle partial zero within the single block */
3957         if (start == end &&
3958             (partial_start || (partial_end != sb->s_blocksize - 1))) {
3959                 err = ext4_block_zero_page_range(handle, mapping,
3960                                                  lstart, length);
3961                 return err;
3962         }
3963         /* Handle partial zero out on the start of the range */
3964         if (partial_start) {
3965                 err = ext4_block_zero_page_range(handle, mapping,
3966                                                  lstart, sb->s_blocksize);
3967                 if (err)
3968                         return err;
3969         }
3970         /* Handle partial zero out on the end of the range */
3971         if (partial_end != sb->s_blocksize - 1)
3972                 err = ext4_block_zero_page_range(handle, mapping,
3973                                                  byte_end - partial_end,
3974                                                  partial_end + 1);
3975         return err;
3976 }
3977 
3978 int ext4_can_truncate(struct inode *inode)
3979 {
3980         if (S_ISREG(inode->i_mode))
3981                 return 1;
3982         if (S_ISDIR(inode->i_mode))
3983                 return 1;
3984         if (S_ISLNK(inode->i_mode))
3985                 return !ext4_inode_is_fast_symlink(inode);
3986         return 0;
3987 }
3988 
3989 /*
3990  * We have to make sure i_disksize gets properly updated before we truncate
3991  * page cache due to hole punching or zero range. Otherwise i_disksize update
3992  * can get lost as it may have been postponed to submission of writeback but
3993  * that will never happen after we truncate page cache.
3994  */
3995 int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset,
3996                                       loff_t len)
3997 {
3998         handle_t *handle;
3999         loff_t size = i_size_read(inode);
4000 
4001         WARN_ON(!inode_is_locked(inode));
4002         if (offset > size || offset + len < size)
4003                 return 0;
4004 
4005         if (EXT4_I(inode)->i_disksize >= size)
4006                 return 0;
4007 
4008         handle = ext4_journal_start(inode, EXT4_HT_MISC, 1);
4009         if (IS_ERR(handle))
4010                 return PTR_ERR(handle);
4011         ext4_update_i_disksize(inode, size);
4012         ext4_mark_inode_dirty(handle, inode);
4013         ext4_journal_stop(handle);
4014 
4015         return 0;
4016 }
4017 
4018 /*
4019  * ext4_punch_hole: punches a hole in a file by releasing the blocks
4020  * associated with the given offset and length
4021  *
4022  * @inode:  File inode
4023  * @offset: The offset where the hole will begin
4024  * @len:    The length of the hole
4025  *
4026  * Returns: 0 on success or negative on failure
4027  */
4028 
4029 int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
4030 {
4031         struct super_block *sb = inode->i_sb;
4032         ext4_lblk_t first_block, stop_block;
4033         struct address_space *mapping = inode->i_mapping;
4034         loff_t first_block_offset, last_block_offset;
4035         handle_t *handle;
4036         unsigned int credits;
4037         int ret = 0;
4038 
4039         if (!S_ISREG(inode->i_mode))
4040                 return -EOPNOTSUPP;
4041 
4042         trace_ext4_punch_hole(inode, offset, length, 0);
4043 
4044         /*
4045          * Write out all dirty pages to avoid race conditions
4046          * Then release them.
4047          */
4048         if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
4049                 ret = filemap_write_and_wait_range(mapping, offset,
4050                                                    offset + length - 1);
4051                 if (ret)
4052                         return ret;
4053         }
4054 
4055         inode_lock(inode);
4056 
4057         /* No need to punch hole beyond i_size */
4058         if (offset >= inode->i_size)
4059                 goto out_mutex;
4060 
4061         /*
4062          * If the hole extends beyond i_size, set the hole
4063          * to end after the page that contains i_size
4064          */
4065         if (offset + length > inode->i_size) {
4066                 length = inode->i_size +
4067                    PAGE_SIZE - (inode->i_size & (PAGE_SIZE - 1)) -
4068                    offset;
4069         }
4070 
4071         if (offset & (sb->s_blocksize - 1) ||
4072             (offset + length) & (sb->s_blocksize - 1)) {
4073                 /*
4074                  * Attach jinode to inode for jbd2 if we do any zeroing of
4075                  * partial block
4076                  */
4077                 ret = ext4_inode_attach_jinode(inode);
4078                 if (ret < 0)
4079                         goto out_mutex;
4080 
4081         }
4082 
4083         /* Wait all existing dio workers, newcomers will block on i_mutex */
4084         ext4_inode_block_unlocked_dio(inode);
4085         inode_dio_wait(inode);
4086 
4087         /*
4088          * Prevent page faults from reinstantiating pages we have released from
4089          * page cache.
4090          */
4091         down_write(&EXT4_I(inode)->i_mmap_sem);
4092         first_block_offset = round_up(offset, sb->s_blocksize);
4093         last_block_offset = round_down((offset + length), sb->s_blocksize) - 1;
4094 
4095         /* Now release the pages and zero block aligned part of pages*/
4096         if (last_block_offset > first_block_offset) {
4097                 ret = ext4_update_disksize_before_punch(inode, offset, length);
4098                 if (ret)
4099                         goto out_dio;
4100                 truncate_pagecache_range(inode, first_block_offset,
4101                                          last_block_offset);
4102         }
4103 
4104         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
4105                 credits = ext4_writepage_trans_blocks(inode);
4106         else
4107                 credits = ext4_blocks_for_truncate(inode);
4108         handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
4109         if (IS_ERR(handle)) {
4110                 ret = PTR_ERR(handle);
4111                 ext4_std_error(sb, ret);
4112                 goto out_dio;
4113         }
4114 
4115         ret = ext4_zero_partial_blocks(handle, inode, offset,
4116                                        length);
4117         if (ret)
4118                 goto out_stop;
4119 
4120         first_block = (offset + sb->s_blocksize - 1) >>
4121                 EXT4_BLOCK_SIZE_BITS(sb);
4122         stop_block = (offset + length) >> EXT4_BLOCK_SIZE_BITS(sb);
4123 
4124         /* If there are no blocks to remove, return now */
4125         if (first_block >= stop_block)
4126                 goto out_stop;
4127 
4128         down_write(&EXT4_I(inode)->i_data_sem);
4129         ext4_discard_preallocations(inode);
4130 
4131         ret = ext4_es_remove_extent(inode, first_block,
4132                                     stop_block - first_block);
4133         if (ret) {
4134                 up_write(&EXT4_I(inode)->i_data_sem);
4135                 goto out_stop;
4136         }
4137 
4138         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
4139                 ret = ext4_ext_remove_space(inode, first_block,
4140                                             stop_block - 1);
4141         else
4142                 ret = ext4_ind_remove_space(handle, inode, first_block,
4143                                             stop_block);
4144 
4145         up_write(&EXT4_I(inode)->i_data_sem);
4146         if (IS_SYNC(inode))
4147                 ext4_handle_sync(handle);
4148 
4149         inode->i_mtime = inode->i_ctime = current_time(inode);
4150         ext4_mark_inode_dirty(handle, inode);
4151 out_stop:
4152         ext4_journal_stop(handle);
4153 out_dio:
4154         up_write(&EXT4_I(inode)->i_mmap_sem);
4155         ext4_inode_resume_unlocked_dio(inode);
4156 out_mutex:
4157         inode_unlock(inode);
4158         return ret;
4159 }
4160 
4161 int ext4_inode_attach_jinode(struct inode *inode)
4162 {
4163         struct ext4_inode_info *ei = EXT4_I(inode);
4164         struct jbd2_inode *jinode;
4165 
4166         if (ei->jinode || !EXT4_SB(inode->i_sb)->s_journal)
4167                 return 0;
4168 
4169         jinode = jbd2_alloc_inode(GFP_KERNEL);
4170         spin_lock(&inode->i_lock);
4171         if (!ei->jinode) {
4172                 if (!jinode) {
4173                         spin_unlock(&inode->i_lock);
4174                         return -ENOMEM;
4175                 }
4176                 ei->jinode = jinode;
4177                 jbd2_journal_init_jbd_inode(ei->jinode, inode);
4178                 jinode = NULL;
4179         }
4180         spin_unlock(&inode->i_lock);
4181         if (unlikely(jinode != NULL))
4182                 jbd2_free_inode(jinode);
4183         return 0;
4184 }
4185 
4186 /*
4187  * ext4_truncate()
4188  *
4189  * We block out ext4_get_block() block instantiations across the entire
4190  * transaction, and VFS/VM ensures that ext4_truncate() cannot run
4191  * simultaneously on behalf of the same inode.
4192  *
4193  * As we work through the truncate and commit bits of it to the journal there
4194  * is one core, guiding principle: the file's tree must always be consistent on
4195  * disk.  We must be able to restart the truncate after a crash.
4196  *
4197  * The file's tree may be transiently inconsistent in memory (although it
4198  * probably isn't), but whenever we close off and commit a journal transaction,
4199  * the contents of (the filesystem + the journal) must be consistent and
4200  * restartable.  It's pretty simple, really: bottom up, right to left (although
4201  * left-to-right works OK too).
4202  *
4203  * Note that at recovery time, journal replay occurs *before* the restart of
4204  * truncate against the orphan inode list.
4205  *
4206  * The committed inode has the new, desired i_size (which is the same as
4207  * i_disksize in this case).  After a crash, ext4_orphan_cleanup() will see
4208  * that this inode's truncate did not complete and it will again call
4209  * ext4_truncate() to have another go.  So there will be instantiated blocks
4210  * to the right of the truncation point in a crashed ext4 filesystem.  But
4211  * that's fine - as long as they are linked from the inode, the post-crash
4212  * ext4_truncate() run will find them and release them.
4213  */
4214 int ext4_truncate(struct inode *inode)
4215 {
4216         struct ext4_inode_info *ei = EXT4_I(inode);
4217         unsigned int credits;
4218         int err = 0;
4219         handle_t *handle;
4220         struct address_space *mapping = inode->i_mapping;
4221 
4222         /*
4223          * There is a possibility that we're either freeing the inode
4224          * or it's a completely new inode. In those cases we might not
4225          * have i_mutex locked because it's not necessary.
4226          */
4227         if (!(inode->i_state & (I_NEW|I_FREEING)))
4228                 WARN_ON(!inode_is_locked(inode));
4229         trace_ext4_truncate_enter(inode);
4230 
4231         if (!ext4_can_truncate(inode))
4232                 return 0;
4233 
4234         ext4_clear_inode_flag(inode, EXT4_INODE_EOFBLOCKS);
4235 
4236         if (inode->i_size == 0 && !test_opt(inode->i_sb, NO_AUTO_DA_ALLOC))
4237                 ext4_set_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
4238 
4239         if (ext4_has_inline_data(inode)) {
4240                 int has_inline = 1;
4241 
4242                 ext4_inline_data_truncate(inode, &has_inline);
4243                 if (has_inline)
4244                         return 0;
4245         }
4246 
4247         /* If we zero-out tail of the page, we have to create jinode for jbd2 */
4248         if (inode->i_size & (inode->i_sb->s_blocksize - 1)) {
4249                 if (ext4_inode_attach_jinode(inode) < 0)
4250                         return 0;
4251         }
4252 
4253         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
4254                 credits = ext4_writepage_trans_blocks(inode);
4255         else
4256                 credits = ext4_blocks_for_truncate(inode);
4257 
4258         handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
4259         if (IS_ERR(handle))
4260                 return PTR_ERR(handle);
4261 
4262         if (inode->i_size & (inode->i_sb->s_blocksize - 1))
4263                 ext4_block_truncate_page(handle, mapping, inode->i_size);
4264 
4265         /*
4266          * We add the inode to the orphan list, so that if this
4267          * truncate spans multiple transactions, and we crash, we will
4268          * resume the truncate when the filesystem recovers.  It also
4269          * marks the inode dirty, to catch the new size.
4270          *
4271          * Implication: the file must always be in a sane, consistent
4272          * truncatable state while each transaction commits.
4273          */
4274         err = ext4_orphan_add(handle, inode);
4275         if (err)
4276                 goto out_stop;
4277 
4278         down_write(&EXT4_I(inode)->i_data_sem);
4279 
4280         ext4_discard_preallocations(inode);
4281 
4282         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
4283                 err = ext4_ext_truncate(handle, inode);
4284         else
4285                 ext4_ind_truncate(handle, inode);
4286 
4287         up_write(&ei->i_data_sem);
4288         if (err)
4289                 goto out_stop;
4290 
4291         if (IS_SYNC(inode))
4292                 ext4_handle_sync(handle);
4293 
4294 out_stop:
4295         /*
4296          * If this was a simple ftruncate() and the file will remain alive,
4297          * then we need to clear up the orphan record which we created above.
4298          * However, if this was a real unlink then we were called by
4299          * ext4_evict_inode(), and we allow that function to clean up the
4300          * orphan info for us.
4301          */
4302         if (inode->i_nlink)
4303                 ext4_orphan_del(handle, inode);
4304 
4305         inode->i_mtime = inode->i_ctime = current_time(inode);
4306         ext4_mark_inode_dirty(handle, inode);
4307         ext4_journal_stop(handle);
4308 
4309         trace_ext4_truncate_exit(inode);
4310         return err;
4311 }
4312 
4313 /*
4314  * ext4_get_inode_loc returns with an extra refcount against the inode's
4315  * underlying buffer_head on success. If 'in_mem' is true, we have all
4316  * data in memory that is needed to recreate the on-disk version of this
4317  * inode.
4318  */
4319 static int __ext4_get_inode_loc(struct inode *inode,
4320                                 struct ext4_iloc *iloc, int in_mem)
4321 {
4322         struct ext4_group_desc  *gdp;
4323         struct buffer_head      *bh;
4324         struct super_block      *sb = inode->i_sb;
4325         ext4_fsblk_t            block;
4326         int                     inodes_per_block, inode_offset;
4327 
4328         iloc->bh = NULL;
4329         if (!ext4_valid_inum(sb, inode->i_ino))
4330                 return -EFSCORRUPTED;
4331 
4332         iloc->block_group = (inode->i_ino - 1) / EXT4_INODES_PER_GROUP(sb);
4333         gdp = ext4_get_group_desc(sb, iloc->block_group, NULL);
4334         if (!gdp)
4335                 return -EIO;
4336 
4337         /*
4338          * Figure out the offset within the block group inode table
4339          */
4340         inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
4341         inode_offset = ((inode->i_ino - 1) %
4342                         EXT4_INODES_PER_GROUP(sb));
4343         block = ext4_inode_table(sb, gdp) + (inode_offset / inodes_per_block);
4344         iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb);
4345 
4346         bh = sb_getblk(sb, block);
4347         if (unlikely(!bh))
4348                 return -ENOMEM;
4349         if (!buffer_uptodate(bh)) {
4350                 lock_buffer(bh);
4351 
4352                 /*
4353                  * If the buffer has the write error flag, we have failed
4354                  * to write out another inode in the same block.  In this
4355                  * case, we don't have to read the block because we may
4356                  * read the old inode data successfully.
4357                  */
4358                 if (buffer_write_io_error(bh) && !buffer_uptodate(bh))
4359                         set_buffer_uptodate(bh);
4360 
4361                 if (buffer_uptodate(bh)) {
4362                         /* someone brought it uptodate while we waited */
4363                         unlock_buffer(bh);
4364                         goto has_buffer;
4365                 }
4366 
4367                 /*
4368                  * If we have all information of the inode in memory and this
4369                  * is the only valid inode in the block, we need not read the
4370                  * block.
4371                  */
4372                 if (in_mem) {
4373                         struct buffer_head *bitmap_bh;
4374                         int i, start;
4375 
4376                         start = inode_offset & ~(inodes_per_block - 1);
4377 
4378                         /* Is the inode bitmap in cache? */
4379                         bitmap_bh = sb_getblk(sb, ext4_inode_bitmap(sb, gdp));
4380                         if (unlikely(!bitmap_bh))
4381                                 goto make_io;
4382 
4383                         /*
4384                          * If the inode bitmap isn't in cache then the
4385                          * optimisation may end up performing two reads instead
4386                          * of one, so skip it.
4387                          */
4388                         if (!buffer_uptodate(bitmap_bh)) {
4389                                 brelse(bitmap_bh);
4390                                 goto make_io;
4391                         }
4392                         for (i = start; i < start + inodes_per_block; i++) {
4393                                 if (i == inode_offset)
4394                                         continue;
4395                                 if (ext4_test_bit(i, bitmap_bh->b_data))
4396                                         break;
4397                         }
4398                         brelse(bitmap_bh);
4399                         if (i == start + inodes_per_block) {
4400                                 /* all other inodes are free, so skip I/O */
4401                                 memset(bh->b_data, 0, bh->b_size);
4402                                 set_buffer_uptodate(bh);
4403                                 unlock_buffer(bh);
4404                                 goto has_buffer;
4405                         }
4406                 }
4407 
4408 make_io:
4409                 /*
4410                  * If we need to do any I/O, try to pre-readahead extra
4411                  * blocks from the inode table.
4412                  */
4413                 if (EXT4_SB(sb)->s_inode_readahead_blks) {
4414                         ext4_fsblk_t b, end, table;
4415                         unsigned num;
4416                         __u32 ra_blks = EXT4_SB(sb)->s_inode_readahead_blks;
4417 
4418                         table = ext4_inode_table(sb, gdp);
4419                         /* s_inode_readahead_blks is always a power of 2 */
4420                         b = block & ~((ext4_fsblk_t) ra_blks - 1);
4421                         if (table > b)
4422                                 b = table;
4423                         end = b + ra_blks;
4424                         num = EXT4_INODES_PER_GROUP(sb);
4425                         if (ext4_has_group_desc_csum(sb))
4426                                 num -= ext4_itable_unused_count(sb, gdp);
4427                         table += num / inodes_per_block;
4428                         if (end > table)
4429                                 end = table;
4430                         while (b <= end)
4431                                 sb_breadahead(sb, b++);
4432                 }
4433 
4434                 /*
4435                  * There are other valid inodes in the buffer, this inode
4436                  * has in-inode xattrs, or we don't have this inode in memory.
4437                  * Read the block from disk.
4438                  */
4439                 trace_ext4_load_inode(inode);
4440                 get_bh(bh);
4441                 bh->b_end_io = end_buffer_read_sync;
4442                 submit_bh(REQ_OP_READ, REQ_META | REQ_PRIO, bh);
4443                 wait_on_buffer(bh);
4444                 if (!buffer_uptodate(bh)) {
4445                         EXT4_ERROR_INODE_BLOCK(inode, block,
4446                                                "unable to read itable block");
4447                         brelse(bh);
4448                         return -EIO;
4449                 }
4450         }
4451 has_buffer:
4452         iloc->bh = bh;
4453         return 0;
4454 }
4455 
4456 int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
4457 {
4458         /* We have all inode data except xattrs in memory here. */
4459         return __ext4_get_inode_loc(inode, iloc,
4460                 !ext4_test_inode_state(inode, EXT4_STATE_XATTR));
4461 }
4462 
4463 void ext4_set_inode_flags(struct inode *inode)
4464 {
4465         unsigned int flags = EXT4_I(inode)->i_flags;
4466         unsigned int new_fl = 0;
4467 
4468         if (flags & EXT4_SYNC_FL)
4469                 new_fl |= S_SYNC;
4470         if (flags & EXT4_APPEND_FL)
4471                 new_fl |= S_APPEND;
4472         if (flags & EXT4_IMMUTABLE_FL)
4473                 new_fl |= S_IMMUTABLE;
4474         if (flags & EXT4_NOATIME_FL)
4475                 new_fl |= S_NOATIME;
4476         if (flags & EXT4_DIRSYNC_FL)
4477                 new_fl |= S_DIRSYNC;
4478         if (test_opt(inode->i_sb, DAX) && S_ISREG(inode->i_mode) &&
4479             !ext4_should_journal_data(inode) && !ext4_has_inline_data(inode) &&
4480             !ext4_encrypted_inode(inode))
4481                 new_fl |= S_DAX;
4482         inode_set_flags(inode, new_fl,
4483                         S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|S_DAX);
4484 }
4485 
4486 /* Propagate flags from i_flags to EXT4_I(inode)->i_flags */
4487 void ext4_get_inode_flags(struct ext4_inode_info *ei)
4488 {
4489         unsigned int vfs_fl;
4490         unsigned long old_fl, new_fl;
4491 
4492         do {
4493                 vfs_fl = ei->vfs_inode.i_flags;
4494                 old_fl = ei->i_flags;
4495                 new_fl = old_fl & ~(EXT4_SYNC_FL|EXT4_APPEND_FL|
4496                                 EXT4_IMMUTABLE_FL|EXT4_NOATIME_FL|
4497                                 EXT4_DIRSYNC_FL);
4498                 if (vfs_fl & S_SYNC)
4499                         new_fl |= EXT4_SYNC_FL;
4500                 if (vfs_fl & S_APPEND)
4501                         new_fl |= EXT4_APPEND_FL;
4502                 if (vfs_fl & S_IMMUTABLE)
4503                         new_fl |= EXT4_IMMUTABLE_FL;
4504                 if (vfs_fl & S_NOATIME)
4505                         new_fl |= EXT4_NOATIME_FL;
4506                 if (vfs_fl & S_DIRSYNC)
4507                         new_fl |= EXT4_DIRSYNC_FL;
4508         } while (cmpxchg(&ei->i_flags, old_fl, new_fl) != old_fl);
4509 }
4510 
4511 static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode,
4512                                   struct ext4_inode_info *ei)
4513 {
4514         blkcnt_t i_blocks ;
4515         struct inode *inode = &(ei->vfs_inode);
4516         struct super_block *sb = inode->i_sb;
4517 
4518         if (ext4_has_feature_huge_file(sb)) {
4519                 /* we are using combined 48 bit field */
4520                 i_blocks = ((u64)le16_to_cpu(raw_inode->i_blocks_high)) << 32 |
4521                                         le32_to_cpu(raw_inode->i_blocks_lo);
4522                 if (ext4_test_inode_flag(inode, EXT4_INODE_HUGE_FILE)) {
4523                         /* i_blocks represent file system block size */
4524                         return i_blocks  << (inode->i_blkbits - 9);
4525                 } else {
4526                         return i_blocks;
4527                 }
4528         } else {
4529                 return le32_to_cpu(raw_inode->i_blocks_lo);
4530         }
4531 }
4532 
4533 static inline void ext4_iget_extra_inode(struct inode *inode,
4534                                          struct ext4_inode *raw_inode,
4535                                          struct ext4_inode_info *ei)
4536 {
4537         __le32 *magic = (void *)raw_inode +
4538                         EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize;
4539         if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize + sizeof(__le32) <=
4540             EXT4_INODE_SIZE(inode->i_sb) &&
4541             *magic == cpu_to_le32(EXT4_XATTR_MAGIC)) {
4542                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
4543                 ext4_find_inline_data_nolock(inode);
4544         } else
4545                 EXT4_I(inode)->i_inline_off = 0;
4546 }
4547 
4548 int ext4_get_projid(struct inode *inode, kprojid_t *projid)
4549 {
4550         if (!ext4_has_feature_project(inode->i_sb))
4551                 return -EOPNOTSUPP;
4552         *projid = EXT4_I(inode)->i_projid;
4553         return 0;
4554 }
4555 
4556 struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
4557 {
4558         struct ext4_iloc iloc;
4559         struct ext4_inode *raw_inode;
4560         struct ext4_inode_info *ei;
4561         struct inode *inode;
4562         journal_t *journal = EXT4_SB(sb)->s_journal;
4563         long ret;
4564         loff_t size;
4565         int block;
4566         uid_t i_uid;
4567         gid_t i_gid;
4568         projid_t i_projid;
4569 
4570         inode = iget_locked(sb, ino);
4571         if (!inode)
4572                 return ERR_PTR(-ENOMEM);
4573         if (!(inode->i_state & I_NEW))
4574                 return inode;
4575 
4576         ei = EXT4_I(inode);
4577         iloc.bh = NULL;
4578 
4579         ret = __ext4_get_inode_loc(inode, &iloc, 0);
4580         if (ret < 0)
4581                 goto bad_inode;
4582         raw_inode = ext4_raw_inode(&iloc);
4583 
4584         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
4585                 ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
4586                 if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
4587                         EXT4_INODE_SIZE(inode->i_sb) ||
4588                     (ei->i_extra_isize & 3)) {
4589                         EXT4_ERROR_INODE(inode,
4590                                          "bad extra_isize %u (inode size %u)",
4591                                          ei->i_extra_isize,
4592                                          EXT4_INODE_SIZE(inode->i_sb));
4593                         ret = -EFSCORRUPTED;
4594                         goto bad_inode;
4595                 }
4596         } else
4597                 ei->i_extra_isize = 0;
4598 
4599         /* Precompute checksum seed for inode metadata */
4600         if (ext4_has_metadata_csum(sb)) {
4601                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
4602                 __u32 csum;
4603                 __le32 inum = cpu_to_le32(inode->i_ino);
4604                 __le32 gen = raw_inode->i_generation;
4605                 csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&inum,
4606                                    sizeof(inum));
4607                 ei->i_csum_seed = ext4_chksum(sbi, csum, (__u8 *)&gen,
4608                                               sizeof(gen));
4609         }
4610 
4611         if (!ext4_inode_csum_verify(inode, raw_inode, ei)) {
4612                 EXT4_ERROR_INODE(inode, "checksum invalid");
4613                 ret = -EFSBADCRC;
4614                 goto bad_inode;
4615         }
4616 
4617         inode->i_mode = le16_to_cpu(raw_inode->i_mode);
4618         i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
4619         i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
4620         if (ext4_has_feature_project(sb) &&
4621             EXT4_INODE_SIZE(sb) > EXT4_GOOD_OLD_INODE_SIZE &&
4622             EXT4_FITS_IN_INODE(raw_inode, ei, i_projid))
4623                 i_projid = (projid_t)le32_to_cpu(raw_inode->i_projid);
4624         else
4625                 i_projid = EXT4_DEF_PROJID;
4626 
4627         if (!(test_opt(inode->i_sb, NO_UID32))) {
4628                 i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
4629                 i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
4630         }
4631         i_uid_write(inode, i_uid);
4632         i_gid_write(inode, i_gid);
4633         ei->i_projid = make_kprojid(&init_user_ns, i_projid);
4634         set_nlink(inode, le16_to_cpu(raw_inode->i_links_count));
4635 
4636         ext4_clear_state_flags(ei);     /* Only relevant on 32-bit archs */
4637         ei->i_inline_off = 0;
4638         ei->i_dir_start_lookup = 0;
4639         ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
4640         /* We now have enough fields to check if the inode was active or not.
4641          * This is needed because nfsd might try to access dead inodes
4642          * the test is that same one that e2fsck uses
4643          * NeilBrown 1999oct15
4644          */
4645         if (inode->i_nlink == 0) {
4646                 if ((inode->i_mode == 0 ||
4647                      !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) &&
4648                     ino != EXT4_BOOT_LOADER_INO) {
4649                         /* this inode is deleted */
4650                         ret = -ESTALE;
4651                         goto bad_inode;
4652                 }
4653                 /* The only unlinked inodes we let through here have
4654                  * valid i_mode and are being read by the orphan
4655                  * recovery code: that's fine, we're about to complete
4656                  * the process of deleting those.
4657                  * OR it is the EXT4_BOOT_LOADER_INO which is
4658                  * not initialized on a new filesystem. */
4659         }
4660         ei->i_flags = le32_to_cpu(raw_inode->i_flags);
4661         inode->i_blocks = ext4_inode_blocks(raw_inode, ei);
4662         ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo);
4663         if (ext4_has_feature_64bit(sb))
4664                 ei->i_file_acl |=
4665                         ((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32;
4666         inode->i_size = ext4_isize(raw_inode);
4667         if ((size = i_size_read(inode)) < 0) {
4668                 EXT4_ERROR_INODE(inode, "bad i_size value: %lld", size);
4669                 ret = -EFSCORRUPTED;
4670                 goto bad_inode;
4671         }
4672         ei->i_disksize = inode->i_size;
4673 #ifdef CONFIG_QUOTA
4674         ei->i_reserved_quota = 0;
4675 #endif
4676         inode->i_generation = le32_to_cpu(raw_inode->i_generation);
4677         ei->i_block_group = iloc.block_group;
4678         ei->i_last_alloc_group = ~0;
4679         /*
4680          * NOTE! The in-memory inode i_data array is in little-endian order
4681          * even on big-endian machines: we do NOT byteswap the block numbers!
4682          */
4683         for (block = 0; block < EXT4_N_BLOCKS; block++)
4684                 ei->i_data[block] = raw_inode->i_block[block];
4685         INIT_LIST_HEAD(&ei->i_orphan);
4686 
4687         /*
4688          * Set transaction id's of transactions that have to be committed
4689          * to finish f[data]sync. We set them to currently running transaction
4690          * as we cannot be sure that the inode or some of its metadata isn't
4691          * part of the transaction - the inode could have been reclaimed and
4692          * now it is reread from disk.
4693          */
4694         if (journal) {
4695                 transaction_t *transaction;
4696                 tid_t tid;
4697 
4698                 read_lock(&journal->j_state_lock);
4699                 if (journal->j_running_transaction)
4700                         transaction = journal->j_running_transaction;
4701                 else
4702                         transaction = journal->j_committing_transaction;
4703                 if (transaction)
4704                         tid = transaction->t_tid;
4705                 else
4706                         tid = journal->j_commit_sequence;
4707                 read_unlock(&journal->j_state_lock);
4708                 ei->i_sync_tid = tid;
4709                 ei->i_datasync_tid = tid;
4710         }
4711 
4712         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
4713                 if (ei->i_extra_isize == 0) {
4714                         /* The extra space is currently unused. Use it. */
4715                         BUILD_BUG_ON(sizeof(struct ext4_inode) & 3);
4716                         ei->i_extra_isize = sizeof(struct ext4_inode) -
4717                                             EXT4_GOOD_OLD_INODE_SIZE;
4718                 } else {
4719                         ext4_iget_extra_inode(inode, raw_inode, ei);
4720                 }
4721         }
4722 
4723         EXT4_INODE_GET_XTIME(i_ctime, inode, raw_inode);
4724         EXT4_INODE_GET_XTIME(i_mtime, inode, raw_inode);
4725         EXT4_INODE_GET_XTIME(i_atime, inode, raw_inode);
4726         EXT4_EINODE_GET_XTIME(i_crtime, ei, raw_inode);
4727 
4728         if (likely(!test_opt2(inode->i_sb, HURD_COMPAT))) {
4729                 inode->i_version = le32_to_cpu(raw_inode->i_disk_version);
4730                 if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
4731                         if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
4732                                 inode->i_version |=
4733                     (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
4734                 }
4735         }
4736 
4737         ret = 0;
4738         if (ei->i_file_acl &&
4739             !ext4_data_block_valid(EXT4_SB(sb), ei->i_file_acl, 1)) {
4740                 EXT4_ERROR_INODE(inode, "bad extended attribute block %llu",
4741                                  ei->i_file_acl);
4742                 ret = -EFSCORRUPTED;
4743                 goto bad_inode;
4744         } else if (!ext4_has_inline_data(inode)) {
4745                 if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
4746                         if ((S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
4747                             (S_ISLNK(inode->i_mode) &&
4748                              !ext4_inode_is_fast_symlink(inode))))
4749                                 /* Validate extent which is part of inode */
4750                                 ret = ext4_ext_check_inode(inode);
4751                 } else if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
4752                            (S_ISLNK(inode->i_mode) &&
4753                             !ext4_inode_is_fast_symlink(inode))) {
4754                         /* Validate block references which are part of inode */
4755                         ret = ext4_ind_check_inode(inode);
4756                 }
4757         }
4758         if (ret)
4759                 goto bad_inode;
4760 
4761         if (S_ISREG(inode->i_mode)) {
4762                 inode->i_op = &ext4_file_inode_operations;
4763                 inode->i_fop = &ext4_file_operations;
4764                 ext4_set_aops(inode);
4765         } else if (S_ISDIR(inode->i_mode)) {
4766                 inode->i_op = &ext4_dir_inode_operations;
4767                 inode->i_fop = &ext4_dir_operations;
4768         } else if (S_ISLNK(inode->i_mode)) {
4769                 if (ext4_encrypted_inode(inode)) {
4770                         inode->i_op = &ext4_encrypted_symlink_inode_operations;
4771                         ext4_set_aops(inode);
4772                 } else if (ext4_inode_is_fast_symlink(inode)) {
4773                         inode->i_link = (char *)ei->i_data;
4774                         inode->i_op = &ext4_fast_symlink_inode_operations;
4775                         nd_terminate_link(ei->i_data, inode->i_size,
4776                                 sizeof(ei->i_data) - 1);
4777                 } else {
4778                         inode->i_op = &ext4_symlink_inode_operations;
4779                         ext4_set_aops(inode);
4780                 }
4781                 inode_nohighmem(inode);
4782         } else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
4783               S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
4784                 inode->i_op = &ext4_special_inode_operations;
4785                 if (raw_inode->i_block[0])
4786                         init_special_inode(inode, inode->i_mode,
4787                            old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
4788                 else
4789                         init_special_inode(inode, inode->i_mode,
4790                            new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
4791         } else if (ino == EXT4_BOOT_LOADER_INO) {
4792                 make_bad_inode(inode);
4793         } else {
4794                 ret = -EFSCORRUPTED;
4795                 EXT4_ERROR_INODE(inode, "bogus i_mode (%o)", inode->i_mode);
4796                 goto bad_inode;
4797         }
4798         brelse(iloc.bh);
4799         ext4_set_inode_flags(inode);
4800         unlock_new_inode(inode);
4801         return inode;
4802 
4803 bad_inode:
4804         brelse(iloc.bh);
4805         iget_failed(inode);
4806         return ERR_PTR(ret);
4807 }
4808 
4809 struct inode *ext4_iget_normal(struct super_block *sb, unsigned long ino)
4810 {
4811         if (ino < EXT4_FIRST_INO(sb) && ino != EXT4_ROOT_INO)
4812                 return ERR_PTR(-EFSCORRUPTED);
4813         return ext4_iget(sb, ino);
4814 }
4815 
4816 static int ext4_inode_blocks_set(handle_t *handle,
4817                                 struct ext4_inode *raw_inode,
4818                                 struct ext4_inode_info *ei)
4819 {
4820         struct inode *inode = &(ei->vfs_inode);
4821         u64 i_blocks = inode->i_blocks;
4822         struct super_block *sb = inode->i_sb;
4823 
4824         if (i_blocks <= ~0U) {
4825                 /*
4826                  * i_blocks can be represented in a 32 bit variable
4827                  * as multiple of 512 bytes
4828                  */
4829                 raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
4830                 raw_inode->i_blocks_high = 0;
4831                 ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
4832                 return 0;
4833         }
4834         if (!ext4_has_feature_huge_file(sb))
4835                 return -EFBIG;
4836 
4837         if (i_blocks <= 0xffffffffffffULL) {
4838                 /*
4839                  * i_blocks can be represented in a 48 bit variable
4840                  * as multiple of 512 bytes
4841                  */
4842                 raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
4843                 raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
4844                 ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
4845         } else {
4846                 ext4_set_inode_flag(inode, EXT4_INODE_HUGE_FILE);
4847                 /* i_block is stored in file system block size */
4848                 i_blocks = i_blocks >> (inode->i_blkbits - 9);
4849                 raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
4850                 raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
4851         }
4852         return 0;
4853 }
4854 
4855 struct other_inode {
4856         unsigned long           orig_ino;
4857         struct ext4_inode       *raw_inode;
4858 };
4859 
4860 static int other_inode_match(struct inode * inode, unsigned long ino,
4861                              void *data)
4862 {
4863         struct other_inode *oi = (struct other_inode *) data;
4864 
4865         if ((inode->i_ino != ino) ||
4866             (inode->i_state & (I_FREEING | I_WILL_FREE | I_NEW |
4867                                I_DIRTY_SYNC | I_DIRTY_DATASYNC)) ||
4868             ((inode->i_state & I_DIRTY_TIME) == 0))
4869                 return 0;
4870         spin_lock(&inode->i_lock);
4871         if (((inode->i_state & (I_FREEING | I_WILL_FREE | I_NEW |
4872                                 I_DIRTY_SYNC | I_DIRTY_DATASYNC)) == 0) &&
4873             (inode->i_state & I_DIRTY_TIME)) {
4874                 struct ext4_inode_info  *ei = EXT4_I(inode);
4875 
4876                 inode->i_state &= ~(I_DIRTY_TIME | I_DIRTY_TIME_EXPIRED);
4877                 spin_unlock(&inode->i_lock);
4878 
4879                 spin_lock(&ei->i_raw_lock);
4880                 EXT4_INODE_SET_XTIME(i_ctime, inode, oi->raw_inode);
4881                 EXT4_INODE_SET_XTIME(i_mtime, inode, oi->raw_inode);
4882                 EXT4_INODE_SET_XTIME(i_atime, inode, oi->raw_inode);
4883                 ext4_inode_csum_set(inode, oi->raw_inode, ei);
4884                 spin_unlock(&ei->i_raw_lock);
4885                 trace_ext4_other_inode_update_time(inode, oi->orig_ino);
4886                 return -1;
4887         }
4888         spin_unlock(&inode->i_lock);
4889         return -1;
4890 }
4891 
4892 /*
4893  * Opportunistically update the other time fields for other inodes in
4894  * the same inode table block.
4895  */
4896 static void ext4_update_other_inodes_time(struct super_block *sb,
4897                                           unsigned long orig_ino, char *buf)
4898 {
4899         struct other_inode oi;
4900         unsigned long ino;
4901         int i, inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
4902         int inode_size = EXT4_INODE_SIZE(sb);
4903 
4904         oi.orig_ino = orig_ino;
4905         /*
4906          * Calculate the first inode in the inode table block.  Inode
4907          * numbers are one-based.  That is, the first inode in a block
4908          * (assuming 4k blocks and 256 byte inodes) is (n*16 + 1).
4909          */
4910         ino = ((orig_ino - 1) & ~(inodes_per_block - 1)) + 1;
4911         for (i = 0; i < inodes_per_block; i++, ino++, buf += inode_size) {
4912                 if (ino == orig_ino)
4913                         continue;
4914                 oi.raw_inode = (struct ext4_inode *) buf;
4915                 (void) find_inode_nowait(sb, ino, other_inode_match, &oi);
4916         }
4917 }
4918 
4919 /*
4920  * Post the struct inode info into an on-disk inode location in the
4921  * buffer-cache.  This gobbles the caller's reference to the
4922  * buffer_head in the inode location struct.
4923  *
4924  * The caller must have write access to iloc->bh.
4925  */
4926 static int ext4_do_update_inode(handle_t *handle,
4927                                 struct inode *inode,
4928                                 struct ext4_iloc *iloc)
4929 {
4930         struct ext4_inode *raw_inode = ext4_raw_inode(iloc);
4931         struct ext4_inode_info *ei = EXT4_I(inode);
4932         struct buffer_head *bh = iloc->bh;
4933         struct super_block *sb = inode->i_sb;
4934         int err = 0, rc, block;
4935         int need_datasync = 0, set_large_file = 0;
4936         uid_t i_uid;
4937         gid_t i_gid;
4938         projid_t i_projid;
4939 
4940         spin_lock(&ei->i_raw_lock);
4941 
4942         /* For fields not tracked in the in-memory inode,
4943          * initialise them to zero for new inodes. */
4944         if (ext4_test_inode_state(inode, EXT4_STATE_NEW))
4945                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
4946 
4947         ext4_get_inode_flags(ei);
4948         raw_inode->i_mode = cpu_to_le16(inode->i_mode);
4949         i_uid = i_uid_read(inode);
4950         i_gid = i_gid_read(inode);
4951         i_projid = from_kprojid(&init_user_ns, ei->i_projid);
4952         if (!(test_opt(inode->i_sb, NO_UID32))) {
4953                 raw_inode->i_uid_low = cpu_to_le16(low_16_bits(i_uid));
4954                 raw_inode->i_gid_low = cpu_to_le16(low_16_bits(i_gid));
4955 /*
4956  * Fix up interoperability with old kernels. Otherwise, old inodes get
4957  * re-used with the upper 16 bits of the uid/gid intact
4958  */
4959                 if (ei->i_dtime && list_empty(&ei->i_orphan)) {
4960                         raw_inode->i_uid_high = 0;
4961                         raw_inode->i_gid_high = 0;
4962                 } else {
4963                         raw_inode->i_uid_high =
4964                                 cpu_to_le16(high_16_bits(i_uid));
4965                         raw_inode->i_gid_high =
4966                                 cpu_to_le16(high_16_bits(i_gid));
4967                 }
4968         } else {
4969                 raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(i_uid));
4970                 raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(i_gid));
4971                 raw_inode->i_uid_high = 0;
4972                 raw_inode->i_gid_high = 0;
4973         }
4974         raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
4975 
4976         EXT4_INODE_SET_XTIME(i_ctime, inode, raw_inode);
4977         EXT4_INODE_SET_XTIME(i_mtime, inode, raw_inode);
4978         EXT4_INODE_SET_XTIME(i_atime, inode, raw_inode);
4979         EXT4_EINODE_SET_XTIME(i_crtime, ei, raw_inode);
4980 
4981         err = ext4_inode_blocks_set(handle, raw_inode, ei);
4982         if (err) {
4983                 spin_unlock(&ei->i_raw_lock);
4984                 goto out_brelse;
4985         }
4986         raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
4987         raw_inode->i_flags = cpu_to_le32(ei->i_flags & 0xFFFFFFFF);
4988         if (likely(!test_opt2(inode->i_sb, HURD_COMPAT)))
4989                 raw_inode->i_file_acl_high =
4990                         cpu_to_le16(ei->i_file_acl >> 32);
4991         raw_inode->i_file_acl_lo = cpu_to_le32(ei->i_file_acl);
4992         if (ei->i_disksize != ext4_isize(raw_inode)) {
4993                 ext4_isize_set(raw_inode, ei->i_disksize);
4994                 need_datasync = 1;
4995         }
4996         if (ei->i_disksize > 0x7fffffffULL) {
4997                 if (!ext4_has_feature_large_file(sb) ||
4998                                 EXT4_SB(sb)->s_es->s_rev_level ==
4999                     cpu_to_le32(EXT4_GOOD_OLD_REV))
5000                         set_large_file = 1;
5001         }
5002         raw_inode->i_generation = cpu_to_le32(inode->i_generation);
5003         if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
5004                 if (old_valid_dev(inode->i_rdev)) {
5005                         raw_inode->i_block[0] =
5006                                 cpu_to_le32(old_encode_dev(inode->i_rdev));
5007                         raw_inode->i_block[1] = 0;
5008                 } else {
5009                         raw_inode->i_block[0] = 0;
5010                         raw_inode->i_block[1] =
5011                                 cpu_to_le32(new_encode_dev(inode->i_rdev));
5012                         raw_inode->i_block[2] = 0;
5013                 }
5014         } else if (!ext4_has_inline_data(inode)) {
5015                 for (block = 0; block < EXT4_N_BLOCKS; block++)
5016                         raw_inode->i_block[block] = ei->i_data[block];
5017         }
5018 
5019         if (likely(!test_opt2(inode->i_sb, HURD_COMPAT))) {
5020                 raw_inode->i_disk_version = cpu_to_le32(inode->i_version);
5021                 if (ei->i_extra_isize) {
5022                         if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
5023                                 raw_inode->i_version_hi =
5024                                         cpu_to_le32(inode->i_version >> 32);
5025                         raw_inode->i_extra_isize =
5026                                 cpu_to_le16(ei->i_extra_isize);
5027                 }
5028         }
5029 
5030         BUG_ON(!ext4_has_feature_project(inode->i_sb) &&
5031                i_projid != EXT4_DEF_PROJID);
5032 
5033         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
5034             EXT4_FITS_IN_INODE(raw_inode, ei, i_projid))
5035                 raw_inode->i_projid = cpu_to_le32(i_projid);
5036 
5037         ext4_inode_csum_set(inode, raw_inode, ei);
5038         spin_unlock(&ei->i_raw_lock);
5039         if (inode->i_sb->s_flags & MS_LAZYTIME)
5040                 ext4_update_other_inodes_time(inode->i_sb, inode->i_ino,
5041                                               bh->b_data);
5042 
5043         BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
5044         rc = ext4_handle_dirty_metadata(handle, NULL, bh);
5045         if (!err)
5046                 err = rc;
5047         ext4_clear_inode_state(inode, EXT4_STATE_NEW);
5048         if (set_large_file) {
5049                 BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get write access");
5050                 err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
5051                 if (err)
5052                         goto out_brelse;
5053                 ext4_update_dynamic_rev(sb);
5054                 ext4_set_feature_large_file(sb);
5055                 ext4_handle_sync(handle);
5056                 err = ext4_handle_dirty_super(handle, sb);
5057         }
5058         ext4_update_inode_fsync_trans(handle, inode, need_datasync);
5059 out_brelse:
5060         brelse(bh);
5061         ext4_std_error(inode->i_sb, err);
5062         return err;
5063 }
5064 
5065 /*
5066  * ext4_write_inode()
5067  *
5068  * We are called from a few places:
5069  *
5070  * - Within generic_file_aio_write() -> generic_write_sync() for O_SYNC files.
5071  *   Here, there will be no transaction running. We wait for any running
5072  *   transaction to commit.
5073  *
5074  * - Within flush work (sys_sync(), kupdate and such).
5075  *   We wait on commit, if told to.
5076  *
5077  * - Within iput_final() -> write_inode_now()
5078  *   We wait on commit, if told to.
5079  *
5080  * In all cases it is actually safe for us to return without doing anything,
5081  * because the inode has been copied into a raw inode buffer in
5082  * ext4_mark_inode_dirty().  This is a correctness thing for WB_SYNC_ALL
5083  * writeback.
5084  *
5085  * Note that we are absolutely dependent upon all inode dirtiers doing the
5086  * right thing: they *must* call mark_inode_dirty() after dirtying info in
5087  * which we are interested.
5088  *
5089  * It would be a bug for them to not do this.  The code:
5090  *
5091  *      mark_inode_dirty(inode)
5092  *      stuff();
5093  *      inode->i_size = expr;
5094  *
5095  * is in error because write_inode() could occur while `stuff()' is running,
5096  * and the new i_size will be lost.  Plus the inode will no longer be on the
5097  * superblock's dirty inode list.
5098  */
5099 int ext4_write_inode(struct inode *inode, struct writeback_control *wbc)
5100 {
5101         int err;
5102 
5103         if (WARN_ON_ONCE(current->flags & PF_MEMALLOC))
5104                 return 0;
5105 
5106         if (EXT4_SB(inode->i_sb)->s_journal) {
5107                 if (ext4_journal_current_handle()) {
5108                         jbd_debug(1, "called recursively, non-PF_MEMALLOC!\n");
5109                         dump_stack();
5110                         return -EIO;
5111                 }
5112 
5113                 /*
5114                  * No need to force transaction in WB_SYNC_NONE mode. Also
5115                  * ext4_sync_fs() will force the commit after everything is
5116                  * written.
5117                  */
5118                 if (wbc->sync_mode != WB_SYNC_ALL || wbc->for_sync)
5119                         return 0;
5120 
5121                 err = ext4_force_commit(inode->i_sb);
5122         } else {
5123                 struct ext4_iloc iloc;
5124 
5125                 err = __ext4_get_inode_loc(inode, &iloc, 0);
5126                 if (err)
5127                         return err;
5128                 /*
5129                  * sync(2) will flush the whole buffer cache. No need to do
5130                  * it here separately for each inode.
5131                  */
5132                 if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync)
5133                         sync_dirty_buffer(iloc.bh);
5134                 if (buffer_req(iloc.bh) && !buffer_uptodate(iloc.bh)) {
5135                         EXT4_ERROR_INODE_BLOCK(inode, iloc.bh->b_blocknr,
5136                                          "IO error syncing inode");
5137                         err = -EIO;
5138                 }
5139                 brelse(iloc.bh);
5140         }
5141         return err;
5142 }
5143 
5144 /*
5145  * In data=journal mode ext4_journalled_invalidatepage() may fail to invalidate
5146  * buffers that are attached to a page stradding i_size and are undergoing
5147  * commit. In that case we have to wait for commit to finish and try again.
5148  */
5149 static void ext4_wait_for_tail_page_commit(struct inode *inode)
5150 {
5151         struct page *page;
5152         unsigned offset;
5153         journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
5154         tid_t commit_tid = 0;
5155         int ret;
5156 
5157         offset = inode->i_size & (PAGE_SIZE - 1);
5158         /*
5159          * All buffers in the last page remain valid? Then there's nothing to
5160          * do. We do the check mainly to optimize the common PAGE_SIZE ==
5161          * blocksize case
5162          */
5163         if (offset > PAGE_SIZE - (1 << inode->i_blkbits))
5164                 return;
5165         while (1) {
5166                 page = find_lock_page(inode->i_mapping,
5167                                       inode->i_size >> PAGE_SHIFT);
5168                 if (!page)
5169                         return;
5170                 ret = __ext4_journalled_invalidatepage(page, offset,
5171                                                 PAGE_SIZE - offset);
5172                 unlock_page(page);
5173                 put_page(page);
5174                 if (ret != -EBUSY)
5175                         return;
5176                 commit_tid = 0;
5177                 read_lock(&journal->j_state_lock);
5178                 if (journal->j_committing_transaction)
5179                         commit_tid = journal->j_committing_transaction->t_tid;
5180                 read_unlock(&journal->j_state_lock);
5181                 if (commit_tid)
5182                         jbd2_log_wait_commit(journal, commit_tid);
5183         }
5184 }
5185 
5186 /*
5187  * ext4_setattr()
5188  *
5189  * Called from notify_change.
5190  *
5191  * We want to trap VFS attempts to truncate the file as soon as
5192  * possible.  In particular, we want to make sure that when the VFS
5193  * shrinks i_size, we put the inode on the orphan list and modify
5194  * i_disksize immediately, so that during the subsequent flushing of
5195  * dirty pages and freeing of disk blocks, we can guarantee that any
5196  * commit will leave the blocks being flushed in an unused state on
5197  * disk.  (On recovery, the inode will get truncated and the blocks will
5198  * be freed, so we have a strong guarantee that no future commit will
5199  * leave these blocks visible to the user.)
5200  *
5201  * Another thing we have to assure is that if we are in ordered mode
5202  * and inode is still attached to the committing transaction, we must
5203  * we start writeout of all the dirty pages which are being truncated.
5204  * This way we are sure that all the data written in the previous
5205  * transaction are already on disk (truncate waits for pages under
5206  * writeback).
5207  *
5208  * Called with inode->i_mutex down.
5209  */
5210 int ext4_setattr(struct dentry *dentry, struct iattr *attr)
5211 {
5212         struct inode *inode = d_inode(dentry);
5213         int error, rc = 0;
5214         int orphan = 0;
5215         const unsigned int ia_valid = attr->ia_valid;
5216 
5217         error = setattr_prepare(dentry, attr);
5218         if (error)
5219                 return error;
5220 
5221         if (is_quota_modification(inode, attr)) {
5222                 error = dquot_initialize(inode);
5223                 if (error)
5224                         return error;
5225         }
5226         if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, inode->i_uid)) ||
5227             (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, inode->i_gid))) {
5228                 handle_t *handle;
5229 
5230                 /* (user+group)*(old+new) structure, inode write (sb,
5231                  * inode block, ? - but truncate inode update has it) */
5232                 handle = ext4_journal_start(inode, EXT4_HT_QUOTA,
5233                         (EXT4_MAXQUOTAS_INIT_BLOCKS(inode->i_sb) +
5234                          EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb)) + 3);
5235                 if (IS_ERR(handle)) {
5236                         error = PTR_ERR(handle);
5237                         goto err_out;
5238                 }
5239                 error = dquot_transfer(inode, attr);
5240                 if (error) {
5241                         ext4_journal_stop(handle);
5242                         return error;
5243                 }
5244                 /* Update corresponding info in inode so that everything is in
5245                  * one transaction */
5246                 if (attr->ia_valid & ATTR_UID)
5247                         inode->i_uid = attr->ia_uid;
5248                 if (attr->ia_valid & ATTR_GID)
5249                         inode->i_gid = attr->ia_gid;
5250                 error = ext4_mark_inode_dirty(handle, inode);
5251                 ext4_journal_stop(handle);
5252         }
5253 
5254         if (attr->ia_valid & ATTR_SIZE) {
5255                 handle_t *handle;
5256                 loff_t oldsize = inode->i_size;
5257                 int shrink = (attr->ia_size <= inode->i_size);
5258 
5259                 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
5260                         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
5261 
5262                         if (attr->ia_size > sbi->s_bitmap_maxbytes)
5263                                 return -EFBIG;
5264                 }
5265                 if (!S_ISREG(inode->i_mode))
5266                         return -EINVAL;
5267 
5268                 if (IS_I_VERSION(inode) && attr->ia_size != inode->i_size)
5269                         inode_inc_iversion(inode);
5270 
5271                 if (ext4_should_order_data(inode) &&
5272                     (attr->ia_size < inode->i_size)) {
5273                         error = ext4_begin_ordered_truncate(inode,
5274                                                             attr->ia_size);
5275                         if (error)
5276                                 goto err_out;
5277                 }
5278                 if (attr->ia_size != inode->i_size) {
5279                         handle = ext4_journal_start(inode, EXT4_HT_INODE, 3);
5280                         if (IS_ERR(handle)) {
5281                                 error = PTR_ERR(handle);
5282                                 goto err_out;
5283                         }
5284                         if (ext4_handle_valid(handle) && shrink) {
5285                                 error = ext4_orphan_add(handle, inode);
5286                                 orphan = 1;
5287                         }
5288                         /*
5289                          * Update c/mtime on truncate up, ext4_truncate() will
5290                          * update c/mtime in shrink case below
5291                          */
5292                         if (!shrink) {
5293                                 inode->i_mtime = current_time(inode);
5294                                 inode->i_ctime = inode->i_mtime;
5295                         }
5296                         down_write(&EXT4_I(inode)->i_data_sem);
5297                         EXT4_I(inode)->i_disksize = attr->ia_size;
5298                         rc = ext4_mark_inode_dirty(handle, inode);
5299                         if (!error)
5300                                 error = rc;
5301                         /*
5302                          * We have to update i_size under i_data_sem together
5303                          * with i_disksize to avoid races with writeback code
5304                          * running ext4_wb_update_i_disksize().
5305                          */
5306                         if (!error)
5307                                 i_size_write(inode, attr->ia_size);
5308                         up_write(&EXT4_I(inode)->i_data_sem);
5309                         ext4_journal_stop(handle);
5310                         if (error) {
5311                                 if (orphan)
5312                                         ext4_orphan_del(NULL, inode);
5313                                 goto err_out;
5314                         }
5315                 }
5316                 if (!shrink)
5317                         pagecache_isize_extended(inode, oldsize, inode->i_size);
5318 
5319                 /*
5320                  * Blocks are going to be removed from the inode. Wait
5321                  * for dio in flight.  Temporarily disable
5322                  * dioread_nolock to prevent livelock.
5323                  */
5324                 if (orphan) {
5325                         if (!ext4_should_journal_data(inode)) {
5326                                 ext4_inode_block_unlocked_dio(inode);
5327                                 inode_dio_wait(inode);
5328                                 ext4_inode_resume_unlocked_dio(inode);
5329                         } else
5330                                 ext4_wait_for_tail_page_commit(inode);
5331                 }
5332                 down_write(&EXT4_I(inode)->i_mmap_sem);
5333                 /*
5334                  * Truncate pagecache after we've waited for commit
5335                  * in data=journal mode to make pages freeable.
5336                  */
5337                 truncate_pagecache(inode, inode->i_size);
5338                 if (shrink) {
5339                         rc = ext4_truncate(inode);
5340                         if (rc)
5341                                 error = rc;
5342                 }
5343                 up_write(&EXT4_I(inode)->i_mmap_sem);
5344         }
5345 
5346         if (!error) {
5347                 setattr_copy(inode, attr);
5348                 mark_inode_dirty(inode);
5349         }
5350 
5351         /*
5352          * If the call to ext4_truncate failed to get a transaction handle at
5353          * all, we need to clean up the in-core orphan list manually.
5354          */
5355         if (orphan && inode->i_nlink)
5356                 ext4_orphan_del(NULL, inode);
5357 
5358         if (!error && (ia_valid & ATTR_MODE))
5359                 rc = posix_acl_chmod(inode, inode->i_mode);
5360 
5361 err_out:
5362         ext4_std_error(inode->i_sb, error);
5363         if (!error)
5364                 error = rc;
5365         return error;
5366 }
5367 
5368 int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry,
5369                  struct kstat *stat)
5370 {
5371         struct inode *inode;
5372         unsigned long long delalloc_blocks;
5373 
5374         inode = d_inode(dentry);
5375         generic_fillattr(inode, stat);
5376 
5377         /*
5378          * If there is inline data in the inode, the inode will normally not
5379          * have data blocks allocated (it may have an external xattr block).
5380          * Report at least one sector for such files, so tools like tar, rsync,
5381          * others doen't incorrectly think the file is completely sparse.
5382          */
5383         if (unlikely(ext4_has_inline_data(inode)))
5384                 stat->blocks += (stat->size + 511) >> 9;
5385 
5386         /*
5387          * We can't update i_blocks if the block allocation is delayed
5388          * otherwise in the case of system crash before the real block
5389          * allocation is done, we will have i_blocks inconsistent with
5390          * on-disk file blocks.
5391          * We always keep i_blocks updated together with real
5392          * allocation. But to not confuse with user, stat
5393          * will return the blocks that include the delayed allocation
5394          * blocks for this file.
5395          */
5396         delalloc_blocks = EXT4_C2B(EXT4_SB(inode->i_sb),
5397                                    EXT4_I(inode)->i_reserved_data_blocks);
5398         stat->blocks += delalloc_blocks << (inode->i_sb->s_blocksize_bits - 9);
5399         return 0;
5400 }
5401 
5402 static int ext4_index_trans_blocks(struct inode *inode, int lblocks,
5403                                    int pextents)
5404 {
5405         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
5406                 return ext4_ind_trans_blocks(inode, lblocks);
5407         return ext4_ext_index_trans_blocks(inode, pextents);
5408 }
5409 
5410 /*
5411  * Account for index blocks, block groups bitmaps and block group
5412  * descriptor blocks if modify datablocks and index blocks
5413  * worse case, the indexs blocks spread over different block groups
5414  *
5415  * If datablocks are discontiguous, they are possible to spread over
5416  * different block groups too. If they are contiguous, with flexbg,
5417  * they could still across block group boundary.
5418  *
5419  * Also account for superblock, inode, quota and xattr blocks
5420  */
5421 static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
5422                                   int pextents)
5423 {
5424         ext4_group_t groups, ngroups = ext4_get_groups_count(inode->i_sb);
5425         int gdpblocks;
5426         int idxblocks;
5427         int ret = 0;
5428 
5429         /*
5430          * How many index blocks need to touch to map @lblocks logical blocks
5431          * to @pextents physical extents?
5432          */
5433         idxblocks = ext4_index_trans_blocks(inode, lblocks, pextents);
5434 
5435         ret = idxblocks;
5436 
5437         /*
5438          * Now let's see how many group bitmaps and group descriptors need
5439          * to account
5440          */
5441         groups = idxblocks + pextents;
5442         gdpblocks = groups;
5443         if (groups > ngroups)
5444                 groups = ngroups;
5445         if (groups > EXT4_SB(inode->i_sb)->s_gdb_count)
5446                 gdpblocks = EXT4_SB(inode->i_sb)->s_gdb_count;
5447 
5448         /* bitmaps and block group descriptor blocks */
5449         ret += groups + gdpblocks;
5450 
5451         /* Blocks for super block, inode, quota and xattr blocks */
5452         ret += EXT4_META_TRANS_BLOCKS(inode->i_sb);
5453 
5454         return ret;
5455 }
5456 
5457 /*
5458  * Calculate the total number of credits to reserve to fit
5459  * the modification of a single pages into a single transaction,
5460  * which may include multiple chunks of block allocations.
5461  *
5462  * This could be called via ext4_write_begin()
5463  *
5464  * We need to consider the worse case, when
5465  * one new block per extent.
5466  */
5467 int ext4_writepage_trans_blocks(struct inode *inode)
5468 {
5469         int bpp = ext4_journal_blocks_per_page(inode);
5470         int ret;
5471 
5472         ret = ext4_meta_trans_blocks(inode, bpp, bpp);
5473 
5474         /* Account for data blocks for journalled mode */
5475         if (ext4_should_journal_data(inode))
5476                 ret += bpp;
5477         return ret;
5478 }
5479 
5480 /*
5481  * Calculate the journal credits for a chunk of data modification.
5482  *
5483  * This is called from DIO, fallocate or whoever calling
5484  * ext4_map_blocks() to map/allocate a chunk of contiguous disk blocks.
5485  *
5486  * journal buffers for data blocks are not included here, as DIO
5487  * and fallocate do no need to journal data buffers.
5488  */
5489 int ext4_chunk_trans_blocks(struct inode *inode, int nrblocks)
5490 {
5491         return ext4_meta_trans_blocks(inode, nrblocks, 1);
5492 }
5493 
5494 /*
5495  * The caller must have previously called ext4_reserve_inode_write().
5496  * Give this, we know that the caller already has write access to iloc->bh.
5497  */
5498 int ext4_mark_iloc_dirty(handle_t *handle,
5499                          struct inode *inode, struct ext4_iloc *iloc)
5500 {
5501         int err = 0;
5502 
5503         if (IS_I_VERSION(inode))
5504                 inode_inc_iversion(inode);
5505 
5506         /* the do_update_inode consumes one bh->b_count */
5507         get_bh(iloc->bh);
5508 
5509         /* ext4_do_update_inode() does jbd2_journal_dirty_metadata */
5510         err = ext4_do_update_inode(handle, inode, iloc);
5511         put_bh(iloc->bh);
5512         return err;
5513 }
5514 
5515 /*
5516  * On success, We end up with an outstanding reference count against
5517  * iloc->bh.  This _must_ be cleaned up later.
5518  */
5519 
5520 int
5521 ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
5522                          struct ext4_iloc *iloc)
5523 {
5524         int err;
5525 
5526         err = ext4_get_inode_loc(inode, iloc);
5527         if (!err) {
5528                 BUFFER_TRACE(iloc->bh, "get_write_access");
5529                 err = ext4_journal_get_write_access(handle, iloc->bh);
5530                 if (err) {
5531                         brelse(iloc->bh);
5532                         iloc->bh = NULL;
5533                 }
5534         }
5535         ext4_std_error(inode->i_sb, err);
5536         return err;
5537 }
5538 
5539 /*
5540  * Expand an inode by new_extra_isize bytes.
5541  * Returns 0 on success or negative error number on failure.
5542  */
5543 static int ext4_expand_extra_isize(struct inode *inode,
5544                                    unsigned int new_extra_isize,
5545                                    struct ext4_iloc iloc,
5546                                    handle_t *handle)
5547 {
5548         struct ext4_inode *raw_inode;
5549         struct ext4_xattr_ibody_header *header;
5550 
5551         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
5552                 return 0;
5553 
5554         raw_inode = ext4_raw_inode(&iloc);
5555 
5556         header = IHDR(inode, raw_inode);
5557 
5558         /* No extended attributes present */
5559         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR) ||
5560             header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)) {
5561                 memset((void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE, 0,
5562                         new_extra_isize);
5563                 EXT4_I(inode)->i_extra_isize = new_extra_isize;
5564                 return 0;
5565         }
5566 
5567         /* try to expand with EAs present */
5568         return ext4_expand_extra_isize_ea(inode, new_extra_isize,
5569                                           raw_inode, handle);
5570 }
5571 
5572 /*
5573  * What we do here is to mark the in-core inode as clean with respect to inode
5574  * dirtiness (it may still be data-dirty).
5575  * This means that the in-core inode may be reaped by prune_icache
5576  * without having to perform any I/O.  This is a very good thing,
5577  * because *any* task may call prune_icache - even ones which
5578  * have a transaction open against a different journal.
5579  *
5580  * Is this cheating?  Not really.  Sure, we haven't written the
5581  * inode out, but prune_icache isn't a user-visible syncing function.
5582  * Whenever the user wants stuff synced (sys_sync, sys_msync, sys_fsync)
5583  * we start and wait on commits.
5584  */
5585 int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
5586 {
5587         struct ext4_iloc iloc;
5588         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
5589         static unsigned int mnt_count;
5590         int err, ret;
5591 
5592         might_sleep();
5593         trace_ext4_mark_inode_dirty(inode, _RET_IP_);
5594         err = ext4_reserve_inode_write(handle, inode, &iloc);
5595         if (err)
5596                 return err;
5597         if (EXT4_I(inode)->i_extra_isize < sbi->s_want_extra_isize &&
5598             !ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND)) {
5599                 /*
5600                  * In nojournal mode, we can immediately attempt to expand
5601                  * the inode.  When journaled, we first need to obtain extra
5602                  * buffer credits since we may write into the EA block
5603                  * with this same handle. If journal_extend fails, then it will
5604                  * only result in a minor loss of functionality for that inode.
5605                  * If this is felt to be critical, then e2fsck should be run to
5606                  * force a large enough s_min_extra_isize.
5607                  */
5608                 if (!ext4_handle_valid(handle) ||
5609                     jbd2_journal_extend(handle,
5610                              EXT4_DATA_TRANS_BLOCKS(inode->i_sb)) == 0) {
5611                         ret = ext4_expand_extra_isize(inode,
5612                                                       sbi->s_want_extra_isize,
5613                                                       iloc, handle);
5614                         if (ret) {
5615                                 if (mnt_count !=
5616                                         le16_to_cpu(sbi->s_es->s_mnt_count)) {
5617                                         ext4_warning(inode->i_sb,
5618                                         "Unable to expand inode %lu. Delete"
5619                                         " some EAs or run e2fsck.",
5620                                         inode->i_ino);
5621                                         mnt_count =
5622                                           le16_to_cpu(sbi->s_es->s_mnt_count);
5623                                 }
5624                         }
5625                 }
5626         }
5627         return ext4_mark_iloc_dirty(handle, inode, &iloc);
5628 }
5629 
5630 /*
5631  * ext4_dirty_inode() is called from __mark_inode_dirty()
5632  *
5633  * We're really interested in the case where a file is being extended.
5634  * i_size has been changed by generic_commit_write() and we thus need
5635  * to include the updated inode in the current transaction.
5636  *
5637  * Also, dquot_alloc_block() will always dirty the inode when blocks
5638  * are allocated to the file.
5639  *
5640  * If the inode is marked synchronous, we don't honour that here - doing
5641  * so would cause a commit on atime updates, which we don't bother doing.
5642  * We handle synchronous inodes at the highest possible level.
5643  *
5644  * If only the I_DIRTY_TIME flag is set, we can skip everything.  If
5645  * I_DIRTY_TIME and I_DIRTY_SYNC is set, the only inode fields we need
5646  * to copy into the on-disk inode structure are the timestamp files.
5647  */
5648 void ext4_dirty_inode(struct inode *inode, int flags)
5649 {
5650         handle_t *handle;
5651 
5652         if (flags == I_DIRTY_TIME)
5653                 return;
5654         handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
5655         if (IS_ERR(handle))
5656                 goto out;
5657 
5658         ext4_mark_inode_dirty(handle, inode);
5659 
5660         ext4_journal_stop(handle);
5661 out:
5662         return;
5663 }
5664 
5665 #if 0
5666 /*
5667  * Bind an inode's backing buffer_head into this transaction, to prevent
5668  * it from being flushed to disk early.  Unlike
5669  * ext4_reserve_inode_write, this leaves behind no bh reference and
5670  * returns no iloc structure, so the caller needs to repeat the iloc
5671  * lookup to mark the inode dirty later.
5672  */
5673 static int ext4_pin_inode(handle_t *handle, struct inode *inode)
5674 {
5675         struct ext4_iloc iloc;
5676 
5677         int err = 0;
5678         if (handle) {
5679                 err = ext4_get_inode_loc(inode, &iloc);
5680                 if (!err) {
5681                         BUFFER_TRACE(iloc.bh, "get_write_access");
5682                         err = jbd2_journal_get_write_access(handle, iloc.bh);
5683                         if (!err)
5684                                 err = ext4_handle_dirty_metadata(handle,
5685                                                                  NULL,
5686                                                                  iloc.bh);
5687                         brelse(iloc.bh);
5688                 }
5689         }
5690         ext4_std_error(inode->i_sb, err);
5691         return err;
5692 }
5693 #endif
5694 
5695 int ext4_change_inode_journal_flag(struct inode *inode, int val)
5696 {
5697         journal_t *journal;
5698         handle_t *handle;
5699         int err;
5700         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
5701 
5702         /*
5703          * We have to be very careful here: changing a data block's
5704          * journaling status dynamically is dangerous.  If we write a
5705          * data block to the journal, change the status and then delete
5706          * that block, we risk forgetting to revoke the old log record
5707          * from the journal and so a subsequent replay can corrupt data.
5708          * So, first we make sure that the journal is empty and that
5709          * nobody is changing anything.
5710          */
5711 
5712         journal = EXT4_JOURNAL(inode);
5713         if (!journal)
5714                 return 0;
5715         if (is_journal_aborted(journal))
5716                 return -EROFS;
5717 
5718         /* Wait for all existing dio workers */
5719         ext4_inode_block_unlocked_dio(inode);
5720         inode_dio_wait(inode);
5721 
5722         /*
5723          * Before flushing the journal and switching inode's aops, we have
5724          * to flush all dirty data the inode has. There can be outstanding
5725          * delayed allocations, there can be unwritten extents created by
5726          * fallocate or buffered writes in dioread_nolock mode covered by
5727          * dirty data which can be converted only after flushing the dirty
5728          * data (and journalled aops don't know how to handle these cases).
5729          */
5730         if (val) {
5731                 down_write(&EXT4_I(inode)->i_mmap_sem);
5732                 err = filemap_write_and_wait(inode->i_mapping);
5733                 if (err < 0) {
5734                         up_write(&EXT4_I(inode)->i_mmap_sem);
5735                         ext4_inode_resume_unlocked_dio(inode);
5736                         return err;
5737                 }
5738         }
5739 
5740         percpu_down_write(&sbi->s_journal_flag_rwsem);
5741         jbd2_journal_lock_updates(journal);
5742 
5743         /*
5744          * OK, there are no updates running now, and all cached data is
5745          * synced to disk.  We are now in a completely consistent state
5746          * which doesn't have anything in the journal, and we know that
5747          * no filesystem updates are running, so it is safe to modify
5748          * the inode's in-core data-journaling state flag now.
5749          */
5750 
5751         if (val)
5752                 ext4_set_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
5753         else {
5754                 err = jbd2_journal_flush(journal);
5755                 if (err < 0) {
5756                         jbd2_journal_unlock_updates(journal);
5757                         percpu_up_write(&sbi->s_journal_flag_rwsem);
5758                         ext4_inode_resume_unlocked_dio(inode);
5759                         return err;
5760                 }
5761                 ext4_clear_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
5762         }
5763         ext4_set_aops(inode);
5764         /*
5765          * Update inode->i_flags after EXT4_INODE_JOURNAL_DATA was updated.
5766          * E.g. S_DAX may get cleared / set.
5767          */
5768         ext4_set_inode_flags(inode);
5769 
5770         jbd2_journal_unlock_updates(journal);
5771         percpu_up_write(&sbi->s_journal_flag_rwsem);
5772 
5773         if (val)
5774                 up_write(&EXT4_I(inode)->i_mmap_sem);
5775         ext4_inode_resume_unlocked_dio(inode);
5776 
5777         /* Finally we can mark the inode as dirty. */
5778 
5779         handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
5780         if (IS_ERR(handle))
5781                 return PTR_ERR(handle);
5782 
5783         err = ext4_mark_inode_dirty(handle, inode);
5784         ext4_handle_sync(handle);
5785         ext4_journal_stop(handle);
5786         ext4_std_error(inode->i_sb, err);
5787 
5788         return err;
5789 }
5790 
5791 static int ext4_bh_unmapped(handle_t *handle, struct buffer_head *bh)
5792 {
5793         return !buffer_mapped(bh);
5794 }
5795 
5796 int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
5797 {
5798         struct page *page = vmf->page;
5799         loff_t size;
5800         unsigned long len;
5801         int ret;
5802         struct file *file = vma->vm_file;
5803         struct inode *inode = file_inode(file);
5804         struct address_space *mapping = inode->i_mapping;
5805         handle_t *handle;
5806         get_block_t *get_block;
5807         int retries = 0;
5808 
5809         sb_start_pagefault(inode->i_sb);
5810         file_update_time(vma->vm_file);
5811 
5812         down_read(&EXT4_I(inode)->i_mmap_sem);
5813 
5814         ret = ext4_convert_inline_data(inode);
5815         if (ret)
5816                 goto out_ret;
5817 
5818         /* Delalloc case is easy... */
5819         if (test_opt(inode->i_sb, DELALLOC) &&
5820             !ext4_should_journal_data(inode) &&
5821             !ext4_nonda_switch(inode->i_sb)) {
5822                 do {
5823                         ret = block_page_mkwrite(vma, vmf,
5824                                                    ext4_da_get_block_prep);
5825                 } while (ret == -ENOSPC &&
5826                        ext4_should_retry_alloc(inode->i_sb, &retries));
5827                 goto out_ret;
5828         }
5829 
5830         lock_page(page);
5831         size = i_size_read(inode);
5832         /* Page got truncated from under us? */