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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 
 41 #include "ext4_jbd2.h"
 42 #include "xattr.h"
 43 #include "acl.h"
 44 #include "truncate.h"
 45 
 46 #include <trace/events/ext4.h>
 47 
 48 #define MPAGE_DA_EXTENT_TAIL 0x01
 49 
 50 static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw,
 51                               struct ext4_inode_info *ei)
 52 {
 53         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 54         __u16 csum_lo;
 55         __u16 csum_hi = 0;
 56         __u32 csum;
 57 
 58         csum_lo = le16_to_cpu(raw->i_checksum_lo);
 59         raw->i_checksum_lo = 0;
 60         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
 61             EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi)) {
 62                 csum_hi = le16_to_cpu(raw->i_checksum_hi);
 63                 raw->i_checksum_hi = 0;
 64         }
 65 
 66         csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)raw,
 67                            EXT4_INODE_SIZE(inode->i_sb));
 68 
 69         raw->i_checksum_lo = cpu_to_le16(csum_lo);
 70         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
 71             EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
 72                 raw->i_checksum_hi = cpu_to_le16(csum_hi);
 73 
 74         return csum;
 75 }
 76 
 77 static int ext4_inode_csum_verify(struct inode *inode, struct ext4_inode *raw,
 78                                   struct ext4_inode_info *ei)
 79 {
 80         __u32 provided, calculated;
 81 
 82         if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
 83             cpu_to_le32(EXT4_OS_LINUX) ||
 84             !ext4_has_metadata_csum(inode->i_sb))
 85                 return 1;
 86 
 87         provided = le16_to_cpu(raw->i_checksum_lo);
 88         calculated = ext4_inode_csum(inode, raw, ei);
 89         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
 90             EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
 91                 provided |= ((__u32)le16_to_cpu(raw->i_checksum_hi)) << 16;
 92         else
 93                 calculated &= 0xFFFF;
 94 
 95         return provided == calculated;
 96 }
 97 
 98 static void ext4_inode_csum_set(struct inode *inode, struct ext4_inode *raw,
 99                                 struct ext4_inode_info *ei)
100 {
101         __u32 csum;
102 
103         if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
104             cpu_to_le32(EXT4_OS_LINUX) ||
105             !ext4_has_metadata_csum(inode->i_sb))
106                 return;
107 
108         csum = ext4_inode_csum(inode, raw, ei);
109         raw->i_checksum_lo = cpu_to_le16(csum & 0xFFFF);
110         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
111             EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
112                 raw->i_checksum_hi = cpu_to_le16(csum >> 16);
113 }
114 
115 static inline int ext4_begin_ordered_truncate(struct inode *inode,
116                                               loff_t new_size)
117 {
118         trace_ext4_begin_ordered_truncate(inode, new_size);
119         /*
120          * If jinode is zero, then we never opened the file for
121          * writing, so there's no need to call
122          * jbd2_journal_begin_ordered_truncate() since there's no
123          * outstanding writes we need to flush.
124          */
125         if (!EXT4_I(inode)->jinode)
126                 return 0;
127         return jbd2_journal_begin_ordered_truncate(EXT4_JOURNAL(inode),
128                                                    EXT4_I(inode)->jinode,
129                                                    new_size);
130 }
131 
132 static void ext4_invalidatepage(struct page *page, unsigned int offset,
133                                 unsigned int length);
134 static int __ext4_journalled_writepage(struct page *page, unsigned int len);
135 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh);
136 static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
137                                   int pextents);
138 
139 /*
140  * Test whether an inode is a fast symlink.
141  */
142 int ext4_inode_is_fast_symlink(struct inode *inode)
143 {
144         int ea_blocks = EXT4_I(inode)->i_file_acl ?
145                 EXT4_CLUSTER_SIZE(inode->i_sb) >> 9 : 0;
146 
147         if (ext4_has_inline_data(inode))
148                 return 0;
149 
150         return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
151 }
152 
153 /*
154  * Restart the transaction associated with *handle.  This does a commit,
155  * so before we call here everything must be consistently dirtied against
156  * this transaction.
157  */
158 int ext4_truncate_restart_trans(handle_t *handle, struct inode *inode,
159                                  int nblocks)
160 {
161         int ret;
162 
163         /*
164          * Drop i_data_sem to avoid deadlock with ext4_map_blocks.  At this
165          * moment, get_block can be called only for blocks inside i_size since
166          * page cache has been already dropped and writes are blocked by
167          * i_mutex. So we can safely drop the i_data_sem here.
168          */
169         BUG_ON(EXT4_JOURNAL(inode) == NULL);
170         jbd_debug(2, "restarting handle %p\n", handle);
171         up_write(&EXT4_I(inode)->i_data_sem);
172         ret = ext4_journal_restart(handle, nblocks);
173         down_write(&EXT4_I(inode)->i_data_sem);
174         ext4_discard_preallocations(inode);
175 
176         return ret;
177 }
178 
179 /*
180  * Called at the last iput() if i_nlink is zero.
181  */
182 void ext4_evict_inode(struct inode *inode)
183 {
184         handle_t *handle;
185         int err;
186 
187         trace_ext4_evict_inode(inode);
188 
189         if (inode->i_nlink) {
190                 /*
191                  * When journalling data dirty buffers are tracked only in the
192                  * journal. So although mm thinks everything is clean and
193                  * ready for reaping the inode might still have some pages to
194                  * write in the running transaction or waiting to be
195                  * checkpointed. Thus calling jbd2_journal_invalidatepage()
196                  * (via truncate_inode_pages()) to discard these buffers can
197                  * cause data loss. Also even if we did not discard these
198                  * buffers, we would have no way to find them after the inode
199                  * is reaped and thus user could see stale data if he tries to
200                  * read them before the transaction is checkpointed. So be
201                  * careful and force everything to disk here... We use
202                  * ei->i_datasync_tid to store the newest transaction
203                  * containing inode's data.
204                  *
205                  * Note that directories do not have this problem because they
206                  * don't use page cache.
207                  */
208                 if (inode->i_ino != EXT4_JOURNAL_INO &&
209                     ext4_should_journal_data(inode) &&
210                     (S_ISLNK(inode->i_mode) || S_ISREG(inode->i_mode))) {
211                         journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
212                         tid_t commit_tid = EXT4_I(inode)->i_datasync_tid;
213 
214                         jbd2_complete_transaction(journal, commit_tid);
215                         filemap_write_and_wait(&inode->i_data);
216                 }
217                 truncate_inode_pages_final(&inode->i_data);
218 
219                 goto no_delete;
220         }
221 
222         if (is_bad_inode(inode))
223                 goto no_delete;
224         dquot_initialize(inode);
225 
226         if (ext4_should_order_data(inode))
227                 ext4_begin_ordered_truncate(inode, 0);
228         truncate_inode_pages_final(&inode->i_data);
229 
230         /*
231          * Protect us against freezing - iput() caller didn't have to have any
232          * protection against it
233          */
234         sb_start_intwrite(inode->i_sb);
235         handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE,
236                                     ext4_blocks_for_truncate(inode)+3);
237         if (IS_ERR(handle)) {
238                 ext4_std_error(inode->i_sb, PTR_ERR(handle));
239                 /*
240                  * If we're going to skip the normal cleanup, we still need to
241                  * make sure that the in-core orphan linked list is properly
242                  * cleaned up.
243                  */
244                 ext4_orphan_del(NULL, inode);
245                 sb_end_intwrite(inode->i_sb);
246                 goto no_delete;
247         }
248 
249         if (IS_SYNC(inode))
250                 ext4_handle_sync(handle);
251         inode->i_size = 0;
252         err = ext4_mark_inode_dirty(handle, inode);
253         if (err) {
254                 ext4_warning(inode->i_sb,
255                              "couldn't mark inode dirty (err %d)", err);
256                 goto stop_handle;
257         }
258         if (inode->i_blocks)
259                 ext4_truncate(inode);
260 
261         /*
262          * ext4_ext_truncate() doesn't reserve any slop when it
263          * restarts journal transactions; therefore there may not be
264          * enough credits left in the handle to remove the inode from
265          * the orphan list and set the dtime field.
266          */
267         if (!ext4_handle_has_enough_credits(handle, 3)) {
268                 err = ext4_journal_extend(handle, 3);
269                 if (err > 0)
270                         err = ext4_journal_restart(handle, 3);
271                 if (err != 0) {
272                         ext4_warning(inode->i_sb,
273                                      "couldn't extend journal (err %d)", err);
274                 stop_handle:
275                         ext4_journal_stop(handle);
276                         ext4_orphan_del(NULL, inode);
277                         sb_end_intwrite(inode->i_sb);
278                         goto no_delete;
279                 }
280         }
281 
282         /*
283          * Kill off the orphan record which ext4_truncate created.
284          * AKPM: I think this can be inside the above `if'.
285          * Note that ext4_orphan_del() has to be able to cope with the
286          * deletion of a non-existent orphan - this is because we don't
287          * know if ext4_truncate() actually created an orphan record.
288          * (Well, we could do this if we need to, but heck - it works)
289          */
290         ext4_orphan_del(handle, inode);
291         EXT4_I(inode)->i_dtime  = get_seconds();
292 
293         /*
294          * One subtle ordering requirement: if anything has gone wrong
295          * (transaction abort, IO errors, whatever), then we can still
296          * do these next steps (the fs will already have been marked as
297          * having errors), but we can't free the inode if the mark_dirty
298          * fails.
299          */
300         if (ext4_mark_inode_dirty(handle, inode))
301                 /* If that failed, just do the required in-core inode clear. */
302                 ext4_clear_inode(inode);
303         else
304                 ext4_free_inode(handle, inode);
305         ext4_journal_stop(handle);
306         sb_end_intwrite(inode->i_sb);
307         return;
308 no_delete:
309         ext4_clear_inode(inode);        /* We must guarantee clearing of inode... */
310 }
311 
312 #ifdef CONFIG_QUOTA
313 qsize_t *ext4_get_reserved_space(struct inode *inode)
314 {
315         return &EXT4_I(inode)->i_reserved_quota;
316 }
317 #endif
318 
319 /*
320  * Called with i_data_sem down, which is important since we can call
321  * ext4_discard_preallocations() from here.
322  */
323 void ext4_da_update_reserve_space(struct inode *inode,
324                                         int used, int quota_claim)
325 {
326         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
327         struct ext4_inode_info *ei = EXT4_I(inode);
328 
329         spin_lock(&ei->i_block_reservation_lock);
330         trace_ext4_da_update_reserve_space(inode, used, quota_claim);
331         if (unlikely(used > ei->i_reserved_data_blocks)) {
332                 ext4_warning(inode->i_sb, "%s: ino %lu, used %d "
333                          "with only %d reserved data blocks",
334                          __func__, inode->i_ino, used,
335                          ei->i_reserved_data_blocks);
336                 WARN_ON(1);
337                 used = ei->i_reserved_data_blocks;
338         }
339 
340         /* Update per-inode reservations */
341         ei->i_reserved_data_blocks -= used;
342         percpu_counter_sub(&sbi->s_dirtyclusters_counter, used);
343 
344         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
345 
346         /* Update quota subsystem for data blocks */
347         if (quota_claim)
348                 dquot_claim_block(inode, EXT4_C2B(sbi, used));
349         else {
350                 /*
351                  * We did fallocate with an offset that is already delayed
352                  * allocated. So on delayed allocated writeback we should
353                  * not re-claim the quota for fallocated blocks.
354                  */
355                 dquot_release_reservation_block(inode, EXT4_C2B(sbi, used));
356         }
357 
358         /*
359          * If we have done all the pending block allocations and if
360          * there aren't any writers on the inode, we can discard the
361          * inode's preallocations.
362          */
363         if ((ei->i_reserved_data_blocks == 0) &&
364             (atomic_read(&inode->i_writecount) == 0))
365                 ext4_discard_preallocations(inode);
366 }
367 
368 static int __check_block_validity(struct inode *inode, const char *func,
369                                 unsigned int line,
370                                 struct ext4_map_blocks *map)
371 {
372         if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), map->m_pblk,
373                                    map->m_len)) {
374                 ext4_error_inode(inode, func, line, map->m_pblk,
375                                  "lblock %lu mapped to illegal pblock "
376                                  "(length %d)", (unsigned long) map->m_lblk,
377                                  map->m_len);
378                 return -EFSCORRUPTED;
379         }
380         return 0;
381 }
382 
383 int ext4_issue_zeroout(struct inode *inode, ext4_lblk_t lblk, ext4_fsblk_t pblk,
384                        ext4_lblk_t len)
385 {
386         int ret;
387 
388         if (ext4_encrypted_inode(inode))
389                 return ext4_encrypted_zeroout(inode, lblk, pblk, len);
390 
391         ret = sb_issue_zeroout(inode->i_sb, pblk, len, GFP_NOFS);
392         if (ret > 0)
393                 ret = 0;
394 
395         return ret;
396 }
397 
398 #define check_block_validity(inode, map)        \
399         __check_block_validity((inode), __func__, __LINE__, (map))
400 
401 #ifdef ES_AGGRESSIVE_TEST
402 static void ext4_map_blocks_es_recheck(handle_t *handle,
403                                        struct inode *inode,
404                                        struct ext4_map_blocks *es_map,
405                                        struct ext4_map_blocks *map,
406                                        int flags)
407 {
408         int retval;
409 
410         map->m_flags = 0;
411         /*
412          * There is a race window that the result is not the same.
413          * e.g. xfstests #223 when dioread_nolock enables.  The reason
414          * is that we lookup a block mapping in extent status tree with
415          * out taking i_data_sem.  So at the time the unwritten extent
416          * could be converted.
417          */
418         down_read(&EXT4_I(inode)->i_data_sem);
419         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
420                 retval = ext4_ext_map_blocks(handle, inode, map, flags &
421                                              EXT4_GET_BLOCKS_KEEP_SIZE);
422         } else {
423                 retval = ext4_ind_map_blocks(handle, inode, map, flags &
424                                              EXT4_GET_BLOCKS_KEEP_SIZE);
425         }
426         up_read((&EXT4_I(inode)->i_data_sem));
427 
428         /*
429          * We don't check m_len because extent will be collpased in status
430          * tree.  So the m_len might not equal.
431          */
432         if (es_map->m_lblk != map->m_lblk ||
433             es_map->m_flags != map->m_flags ||
434             es_map->m_pblk != map->m_pblk) {
435                 printk("ES cache assertion failed for inode: %lu "
436                        "es_cached ex [%d/%d/%llu/%x] != "
437                        "found ex [%d/%d/%llu/%x] retval %d flags %x\n",
438                        inode->i_ino, es_map->m_lblk, es_map->m_len,
439                        es_map->m_pblk, es_map->m_flags, map->m_lblk,
440                        map->m_len, map->m_pblk, map->m_flags,
441                        retval, flags);
442         }
443 }
444 #endif /* ES_AGGRESSIVE_TEST */
445 
446 /*
447  * The ext4_map_blocks() function tries to look up the requested blocks,
448  * and returns if the blocks are already mapped.
449  *
450  * Otherwise it takes the write lock of the i_data_sem and allocate blocks
451  * and store the allocated blocks in the result buffer head and mark it
452  * mapped.
453  *
454  * If file type is extents based, it will call ext4_ext_map_blocks(),
455  * Otherwise, call with ext4_ind_map_blocks() to handle indirect mapping
456  * based files
457  *
458  * On success, it returns the number of blocks being mapped or allocated.  if
459  * create==0 and the blocks are pre-allocated and unwritten, the resulting @map
460  * is marked as unwritten. If the create == 1, it will mark @map as mapped.
461  *
462  * It returns 0 if plain look up failed (blocks have not been allocated), in
463  * that case, @map is returned as unmapped but we still do fill map->m_len to
464  * indicate the length of a hole starting at map->m_lblk.
465  *
466  * It returns the error in case of allocation failure.
467  */
468 int ext4_map_blocks(handle_t *handle, struct inode *inode,
469                     struct ext4_map_blocks *map, int flags)
470 {
471         struct extent_status es;
472         int retval;
473         int ret = 0;
474 #ifdef ES_AGGRESSIVE_TEST
475         struct ext4_map_blocks orig_map;
476 
477         memcpy(&orig_map, map, sizeof(*map));
478 #endif
479 
480         map->m_flags = 0;
481         ext_debug("ext4_map_blocks(): inode %lu, flag %d, max_blocks %u,"
482                   "logical block %lu\n", inode->i_ino, flags, map->m_len,
483                   (unsigned long) map->m_lblk);
484 
485         /*
486          * ext4_map_blocks returns an int, and m_len is an unsigned int
487          */
488         if (unlikely(map->m_len > INT_MAX))
489                 map->m_len = INT_MAX;
490 
491         /* We can handle the block number less than EXT_MAX_BLOCKS */
492         if (unlikely(map->m_lblk >= EXT_MAX_BLOCKS))
493                 return -EFSCORRUPTED;
494 
495         /* Lookup extent status tree firstly */
496         if (ext4_es_lookup_extent(inode, map->m_lblk, &es)) {
497                 if (ext4_es_is_written(&es) || ext4_es_is_unwritten(&es)) {
498                         map->m_pblk = ext4_es_pblock(&es) +
499                                         map->m_lblk - es.es_lblk;
500                         map->m_flags |= ext4_es_is_written(&es) ?
501                                         EXT4_MAP_MAPPED : EXT4_MAP_UNWRITTEN;
502                         retval = es.es_len - (map->m_lblk - es.es_lblk);
503                         if (retval > map->m_len)
504                                 retval = map->m_len;
505                         map->m_len = retval;
506                 } else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) {
507                         map->m_pblk = 0;
508                         retval = es.es_len - (map->m_lblk - es.es_lblk);
509                         if (retval > map->m_len)
510                                 retval = map->m_len;
511                         map->m_len = retval;
512                         retval = 0;
513                 } else {
514                         BUG_ON(1);
515                 }
516 #ifdef ES_AGGRESSIVE_TEST
517                 ext4_map_blocks_es_recheck(handle, inode, map,
518                                            &orig_map, flags);
519 #endif
520                 goto found;
521         }
522 
523         /*
524          * Try to see if we can get the block without requesting a new
525          * file system block.
526          */
527         down_read(&EXT4_I(inode)->i_data_sem);
528         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
529                 retval = ext4_ext_map_blocks(handle, inode, map, flags &
530                                              EXT4_GET_BLOCKS_KEEP_SIZE);
531         } else {
532                 retval = ext4_ind_map_blocks(handle, inode, map, flags &
533                                              EXT4_GET_BLOCKS_KEEP_SIZE);
534         }
535         if (retval > 0) {
536                 unsigned int status;
537 
538                 if (unlikely(retval != map->m_len)) {
539                         ext4_warning(inode->i_sb,
540                                      "ES len assertion failed for inode "
541                                      "%lu: retval %d != map->m_len %d",
542                                      inode->i_ino, retval, map->m_len);
543                         WARN_ON(1);
544                 }
545 
546                 status = map->m_flags & EXT4_MAP_UNWRITTEN ?
547                                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
548                 if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
549                     !(status & EXTENT_STATUS_WRITTEN) &&
550                     ext4_find_delalloc_range(inode, map->m_lblk,
551                                              map->m_lblk + map->m_len - 1))
552                         status |= EXTENT_STATUS_DELAYED;
553                 ret = ext4_es_insert_extent(inode, map->m_lblk,
554                                             map->m_len, map->m_pblk, status);
555                 if (ret < 0)
556                         retval = ret;
557         }
558         up_read((&EXT4_I(inode)->i_data_sem));
559 
560 found:
561         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
562                 ret = check_block_validity(inode, map);
563                 if (ret != 0)
564                         return ret;
565         }
566 
567         /* If it is only a block(s) look up */
568         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
569                 return retval;
570 
571         /*
572          * Returns if the blocks have already allocated
573          *
574          * Note that if blocks have been preallocated
575          * ext4_ext_get_block() returns the create = 0
576          * with buffer head unmapped.
577          */
578         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED)
579                 /*
580                  * If we need to convert extent to unwritten
581                  * we continue and do the actual work in
582                  * ext4_ext_map_blocks()
583                  */
584                 if (!(flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN))
585                         return retval;
586 
587         /*
588          * Here we clear m_flags because after allocating an new extent,
589          * it will be set again.
590          */
591         map->m_flags &= ~EXT4_MAP_FLAGS;
592 
593         /*
594          * New blocks allocate and/or writing to unwritten extent
595          * will possibly result in updating i_data, so we take
596          * the write lock of i_data_sem, and call get_block()
597          * with create == 1 flag.
598          */
599         down_write(&EXT4_I(inode)->i_data_sem);
600 
601         /*
602          * We need to check for EXT4 here because migrate
603          * could have changed the inode type in between
604          */
605         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
606                 retval = ext4_ext_map_blocks(handle, inode, map, flags);
607         } else {
608                 retval = ext4_ind_map_blocks(handle, inode, map, flags);
609 
610                 if (retval > 0 && map->m_flags & EXT4_MAP_NEW) {
611                         /*
612                          * We allocated new blocks which will result in
613                          * i_data's format changing.  Force the migrate
614                          * to fail by clearing migrate flags
615                          */
616                         ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
617                 }
618 
619                 /*
620                  * Update reserved blocks/metadata blocks after successful
621                  * block allocation which had been deferred till now. We don't
622                  * support fallocate for non extent files. So we can update
623                  * reserve space here.
624                  */
625                 if ((retval > 0) &&
626                         (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE))
627                         ext4_da_update_reserve_space(inode, retval, 1);
628         }
629 
630         if (retval > 0) {
631                 unsigned int status;
632 
633                 if (unlikely(retval != map->m_len)) {
634                         ext4_warning(inode->i_sb,
635                                      "ES len assertion failed for inode "
636                                      "%lu: retval %d != map->m_len %d",
637                                      inode->i_ino, retval, map->m_len);
638                         WARN_ON(1);
639                 }
640 
641                 /*
642                  * We have to zeroout blocks before inserting them into extent
643                  * status tree. Otherwise someone could look them up there and
644                  * use them before they are really zeroed.
645                  */
646                 if (flags & EXT4_GET_BLOCKS_ZERO &&
647                     map->m_flags & EXT4_MAP_MAPPED &&
648                     map->m_flags & EXT4_MAP_NEW) {
649                         ret = ext4_issue_zeroout(inode, map->m_lblk,
650                                                  map->m_pblk, map->m_len);
651                         if (ret) {
652                                 retval = ret;
653                                 goto out_sem;
654                         }
655                 }
656 
657                 /*
658                  * If the extent has been zeroed out, we don't need to update
659                  * extent status tree.
660                  */
661                 if ((flags & EXT4_GET_BLOCKS_PRE_IO) &&
662                     ext4_es_lookup_extent(inode, map->m_lblk, &es)) {
663                         if (ext4_es_is_written(&es))
664                                 goto out_sem;
665                 }
666                 status = map->m_flags & EXT4_MAP_UNWRITTEN ?
667                                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
668                 if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
669                     !(status & EXTENT_STATUS_WRITTEN) &&
670                     ext4_find_delalloc_range(inode, map->m_lblk,
671                                              map->m_lblk + map->m_len - 1))
672                         status |= EXTENT_STATUS_DELAYED;
673                 ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
674                                             map->m_pblk, status);
675                 if (ret < 0) {
676                         retval = ret;
677                         goto out_sem;
678                 }
679         }
680 
681 out_sem:
682         up_write((&EXT4_I(inode)->i_data_sem));
683         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
684                 ret = check_block_validity(inode, map);
685                 if (ret != 0)
686                         return ret;
687 
688                 /*
689                  * Inodes with freshly allocated blocks where contents will be
690                  * visible after transaction commit must be on transaction's
691                  * ordered data list.
692                  */
693                 if (map->m_flags & EXT4_MAP_NEW &&
694                     !(map->m_flags & EXT4_MAP_UNWRITTEN) &&
695                     !(flags & EXT4_GET_BLOCKS_ZERO) &&
696                     !IS_NOQUOTA(inode) &&
697                     ext4_should_order_data(inode)) {
698                         ret = ext4_jbd2_file_inode(handle, inode);
699                         if (ret)
700                                 return ret;
701                 }
702         }
703         return retval;
704 }
705 
706 /*
707  * Update EXT4_MAP_FLAGS in bh->b_state. For buffer heads attached to pages
708  * we have to be careful as someone else may be manipulating b_state as well.
709  */
710 static void ext4_update_bh_state(struct buffer_head *bh, unsigned long flags)
711 {
712         unsigned long old_state;
713         unsigned long new_state;
714 
715         flags &= EXT4_MAP_FLAGS;
716 
717         /* Dummy buffer_head? Set non-atomically. */
718         if (!bh->b_page) {
719                 bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | flags;
720                 return;
721         }
722         /*
723          * Someone else may be modifying b_state. Be careful! This is ugly but
724          * once we get rid of using bh as a container for mapping information
725          * to pass to / from get_block functions, this can go away.
726          */
727         do {
728                 old_state = READ_ONCE(bh->b_state);
729                 new_state = (old_state & ~EXT4_MAP_FLAGS) | flags;
730         } while (unlikely(
731                  cmpxchg(&bh->b_state, old_state, new_state) != old_state));
732 }
733 
734 static int _ext4_get_block(struct inode *inode, sector_t iblock,
735                            struct buffer_head *bh, int flags)
736 {
737         struct ext4_map_blocks map;
738         int ret = 0;
739 
740         if (ext4_has_inline_data(inode))
741                 return -ERANGE;
742 
743         map.m_lblk = iblock;
744         map.m_len = bh->b_size >> inode->i_blkbits;
745 
746         ret = ext4_map_blocks(ext4_journal_current_handle(), inode, &map,
747                               flags);
748         if (ret > 0) {
749                 map_bh(bh, inode->i_sb, map.m_pblk);
750                 ext4_update_bh_state(bh, map.m_flags);
751                 bh->b_size = inode->i_sb->s_blocksize * map.m_len;
752                 ret = 0;
753         }
754         return ret;
755 }
756 
757 int ext4_get_block(struct inode *inode, sector_t iblock,
758                    struct buffer_head *bh, int create)
759 {
760         return _ext4_get_block(inode, iblock, bh,
761                                create ? EXT4_GET_BLOCKS_CREATE : 0);
762 }
763 
764 /*
765  * Get block function used when preparing for buffered write if we require
766  * creating an unwritten extent if blocks haven't been allocated.  The extent
767  * will be converted to written after the IO is complete.
768  */
769 int ext4_get_block_unwritten(struct inode *inode, sector_t iblock,
770                              struct buffer_head *bh_result, int create)
771 {
772         ext4_debug("ext4_get_block_unwritten: inode %lu, create flag %d\n",
773                    inode->i_ino, create);
774         return _ext4_get_block(inode, iblock, bh_result,
775                                EXT4_GET_BLOCKS_IO_CREATE_EXT);
776 }
777 
778 /* Maximum number of blocks we map for direct IO at once. */
779 #define DIO_MAX_BLOCKS 4096
780 
781 /*
782  * Get blocks function for the cases that need to start a transaction -
783  * generally difference cases of direct IO and DAX IO. It also handles retries
784  * in case of ENOSPC.
785  */
786 static int ext4_get_block_trans(struct inode *inode, sector_t iblock,
787                                 struct buffer_head *bh_result, int flags)
788 {
789         int dio_credits;
790         handle_t *handle;
791         int retries = 0;
792         int ret;
793 
794         /* Trim mapping request to maximum we can map at once for DIO */
795         if (bh_result->b_size >> inode->i_blkbits > DIO_MAX_BLOCKS)
796                 bh_result->b_size = DIO_MAX_BLOCKS << inode->i_blkbits;
797         dio_credits = ext4_chunk_trans_blocks(inode,
798                                       bh_result->b_size >> inode->i_blkbits);
799 retry:
800         handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, dio_credits);
801         if (IS_ERR(handle))
802                 return PTR_ERR(handle);
803 
804         ret = _ext4_get_block(inode, iblock, bh_result, flags);
805         ext4_journal_stop(handle);
806 
807         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
808                 goto retry;
809         return ret;
810 }
811 
812 /* Get block function for DIO reads and writes to inodes without extents */
813 int ext4_dio_get_block(struct inode *inode, sector_t iblock,
814                        struct buffer_head *bh, int create)
815 {
816         /* We don't expect handle for direct IO */
817         WARN_ON_ONCE(ext4_journal_current_handle());
818 
819         if (!create)
820                 return _ext4_get_block(inode, iblock, bh, 0);
821         return ext4_get_block_trans(inode, iblock, bh, EXT4_GET_BLOCKS_CREATE);
822 }
823 
824 /*
825  * Get block function for AIO DIO writes when we create unwritten extent if
826  * blocks are not allocated yet. The extent will be converted to written
827  * after IO is complete.
828  */
829 static int ext4_dio_get_block_unwritten_async(struct inode *inode,
830                 sector_t iblock, struct buffer_head *bh_result, int create)
831 {
832         int ret;
833 
834         /* We don't expect handle for direct IO */
835         WARN_ON_ONCE(ext4_journal_current_handle());
836 
837         ret = ext4_get_block_trans(inode, iblock, bh_result,
838                                    EXT4_GET_BLOCKS_IO_CREATE_EXT);
839 
840         /*
841          * When doing DIO using unwritten extents, we need io_end to convert
842          * unwritten extents to written on IO completion. We allocate io_end
843          * once we spot unwritten extent and store it in b_private. Generic
844          * DIO code keeps b_private set and furthermore passes the value to
845          * our completion callback in 'private' argument.
846          */
847         if (!ret && buffer_unwritten(bh_result)) {
848                 if (!bh_result->b_private) {
849                         ext4_io_end_t *io_end;
850 
851                         io_end = ext4_init_io_end(inode, GFP_KERNEL);
852                         if (!io_end)
853                                 return -ENOMEM;
854                         bh_result->b_private = io_end;
855                         ext4_set_io_unwritten_flag(inode, io_end);
856                 }
857                 set_buffer_defer_completion(bh_result);
858         }
859 
860         return ret;
861 }
862 
863 /*
864  * Get block function for non-AIO DIO writes when we create unwritten extent if
865  * blocks are not allocated yet. The extent will be converted to written
866  * after IO is complete from ext4_ext_direct_IO() function.
867  */
868 static int ext4_dio_get_block_unwritten_sync(struct inode *inode,
869                 sector_t iblock, struct buffer_head *bh_result, int create)
870 {
871         int ret;
872 
873         /* We don't expect handle for direct IO */
874         WARN_ON_ONCE(ext4_journal_current_handle());
875 
876         ret = ext4_get_block_trans(inode, iblock, bh_result,
877                                    EXT4_GET_BLOCKS_IO_CREATE_EXT);
878 
879         /*
880          * Mark inode as having pending DIO writes to unwritten extents.
881          * ext4_ext_direct_IO() checks this flag and converts extents to
882          * written.
883          */
884         if (!ret && buffer_unwritten(bh_result))
885                 ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
886 
887         return ret;
888 }
889 
890 static int ext4_dio_get_block_overwrite(struct inode *inode, sector_t iblock,
891                    struct buffer_head *bh_result, int create)
892 {
893         int ret;
894 
895         ext4_debug("ext4_dio_get_block_overwrite: inode %lu, create flag %d\n",
896                    inode->i_ino, create);
897         /* We don't expect handle for direct IO */
898         WARN_ON_ONCE(ext4_journal_current_handle());
899 
900         ret = _ext4_get_block(inode, iblock, bh_result, 0);
901         /*
902          * Blocks should have been preallocated! ext4_file_write_iter() checks
903          * that.
904          */
905         WARN_ON_ONCE(!buffer_mapped(bh_result) || buffer_unwritten(bh_result));
906 
907         return ret;
908 }
909 
910 
911 /*
912  * `handle' can be NULL if create is zero
913  */
914 struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
915                                 ext4_lblk_t block, int map_flags)
916 {
917         struct ext4_map_blocks map;
918         struct buffer_head *bh;
919         int create = map_flags & EXT4_GET_BLOCKS_CREATE;
920         int err;
921 
922         J_ASSERT(handle != NULL || create == 0);
923 
924         map.m_lblk = block;
925         map.m_len = 1;
926         err = ext4_map_blocks(handle, inode, &map, map_flags);
927 
928         if (err == 0)
929                 return create ? ERR_PTR(-ENOSPC) : NULL;
930         if (err < 0)
931                 return ERR_PTR(err);
932 
933         bh = sb_getblk(inode->i_sb, map.m_pblk);
934         if (unlikely(!bh))
935                 return ERR_PTR(-ENOMEM);
936         if (map.m_flags & EXT4_MAP_NEW) {
937                 J_ASSERT(create != 0);
938                 J_ASSERT(handle != NULL);
939 
940                 /*
941                  * Now that we do not always journal data, we should
942                  * keep in mind whether this should always journal the
943                  * new buffer as metadata.  For now, regular file
944                  * writes use ext4_get_block instead, so it's not a
945                  * problem.
946                  */
947                 lock_buffer(bh);
948                 BUFFER_TRACE(bh, "call get_create_access");
949                 err = ext4_journal_get_create_access(handle, bh);
950                 if (unlikely(err)) {
951                         unlock_buffer(bh);
952                         goto errout;
953                 }
954                 if (!buffer_uptodate(bh)) {
955                         memset(bh->b_data, 0, inode->i_sb->s_blocksize);
956                         set_buffer_uptodate(bh);
957                 }
958                 unlock_buffer(bh);
959                 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
960                 err = ext4_handle_dirty_metadata(handle, inode, bh);
961                 if (unlikely(err))
962                         goto errout;
963         } else
964                 BUFFER_TRACE(bh, "not a new buffer");
965         return bh;
966 errout:
967         brelse(bh);
968         return ERR_PTR(err);
969 }
970 
971 struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
972                                ext4_lblk_t block, int map_flags)
973 {
974         struct buffer_head *bh;
975 
976         bh = ext4_getblk(handle, inode, block, map_flags);
977         if (IS_ERR(bh))
978                 return bh;
979         if (!bh || buffer_uptodate(bh))
980                 return bh;
981         ll_rw_block(READ | REQ_META | REQ_PRIO, 1, &bh);
982         wait_on_buffer(bh);
983         if (buffer_uptodate(bh))
984                 return bh;
985         put_bh(bh);
986         return ERR_PTR(-EIO);
987 }
988 
989 int ext4_walk_page_buffers(handle_t *handle,
990                            struct buffer_head *head,
991                            unsigned from,
992                            unsigned to,
993                            int *partial,
994                            int (*fn)(handle_t *handle,
995                                      struct buffer_head *bh))
996 {
997         struct buffer_head *bh;
998         unsigned block_start, block_end;
999         unsigned blocksize = head->b_size;
1000         int err, ret = 0;
1001         struct buffer_head *next;
1002 
1003         for (bh = head, block_start = 0;
1004              ret == 0 && (bh != head || !block_start);
1005              block_start = block_end, bh = next) {
1006                 next = bh->b_this_page;
1007                 block_end = block_start + blocksize;
1008                 if (block_end <= from || block_start >= to) {
1009                         if (partial && !buffer_uptodate(bh))
1010                                 *partial = 1;
1011                         continue;
1012                 }
1013                 err = (*fn)(handle, bh);
1014                 if (!ret)
1015                         ret = err;
1016         }
1017         return ret;
1018 }
1019 
1020 /*
1021  * To preserve ordering, it is essential that the hole instantiation and
1022  * the data write be encapsulated in a single transaction.  We cannot
1023  * close off a transaction and start a new one between the ext4_get_block()
1024  * and the commit_write().  So doing the jbd2_journal_start at the start of
1025  * prepare_write() is the right place.
1026  *
1027  * Also, this function can nest inside ext4_writepage().  In that case, we
1028  * *know* that ext4_writepage() has generated enough buffer credits to do the
1029  * whole page.  So we won't block on the journal in that case, which is good,
1030  * because the caller may be PF_MEMALLOC.
1031  *
1032  * By accident, ext4 can be reentered when a transaction is open via
1033  * quota file writes.  If we were to commit the transaction while thus
1034  * reentered, there can be a deadlock - we would be holding a quota
1035  * lock, and the commit would never complete if another thread had a
1036  * transaction open and was blocking on the quota lock - a ranking
1037  * violation.
1038  *
1039  * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
1040  * will _not_ run commit under these circumstances because handle->h_ref
1041  * is elevated.  We'll still have enough credits for the tiny quotafile
1042  * write.
1043  */
1044 int do_journal_get_write_access(handle_t *handle,
1045                                 struct buffer_head *bh)
1046 {
1047         int dirty = buffer_dirty(bh);
1048         int ret;
1049 
1050         if (!buffer_mapped(bh) || buffer_freed(bh))
1051                 return 0;
1052         /*
1053          * __block_write_begin() could have dirtied some buffers. Clean
1054          * the dirty bit as jbd2_journal_get_write_access() could complain
1055          * otherwise about fs integrity issues. Setting of the dirty bit
1056          * by __block_write_begin() isn't a real problem here as we clear
1057          * the bit before releasing a page lock and thus writeback cannot
1058          * ever write the buffer.
1059          */
1060         if (dirty)
1061                 clear_buffer_dirty(bh);
1062         BUFFER_TRACE(bh, "get write access");
1063         ret = ext4_journal_get_write_access(handle, bh);
1064         if (!ret && dirty)
1065                 ret = ext4_handle_dirty_metadata(handle, NULL, bh);
1066         return ret;
1067 }
1068 
1069 #ifdef CONFIG_EXT4_FS_ENCRYPTION
1070 static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
1071                                   get_block_t *get_block)
1072 {
1073         unsigned from = pos & (PAGE_SIZE - 1);
1074         unsigned to = from + len;
1075         struct inode *inode = page->mapping->host;
1076         unsigned block_start, block_end;
1077         sector_t block;
1078         int err = 0;
1079         unsigned blocksize = inode->i_sb->s_blocksize;
1080         unsigned bbits;
1081         struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
1082         bool decrypt = false;
1083 
1084         BUG_ON(!PageLocked(page));
1085         BUG_ON(from > PAGE_SIZE);
1086         BUG_ON(to > PAGE_SIZE);
1087         BUG_ON(from > to);
1088 
1089         if (!page_has_buffers(page))
1090                 create_empty_buffers(page, blocksize, 0);
1091         head = page_buffers(page);
1092         bbits = ilog2(blocksize);
1093         block = (sector_t)page->index << (PAGE_SHIFT - bbits);
1094 
1095         for (bh = head, block_start = 0; bh != head || !block_start;
1096             block++, block_start = block_end, bh = bh->b_this_page) {
1097                 block_end = block_start + blocksize;
1098                 if (block_end <= from || block_start >= to) {
1099                         if (PageUptodate(page)) {
1100                                 if (!buffer_uptodate(bh))
1101                                         set_buffer_uptodate(bh);
1102                         }
1103                         continue;
1104                 }
1105                 if (buffer_new(bh))
1106                         clear_buffer_new(bh);
1107                 if (!buffer_mapped(bh)) {
1108                         WARN_ON(bh->b_size != blocksize);
1109                         err = get_block(inode, block, bh, 1);
1110                         if (err)
1111                                 break;
1112                         if (buffer_new(bh)) {
1113                                 unmap_underlying_metadata(bh->b_bdev,
1114                                                           bh->b_blocknr);
1115                                 if (PageUptodate(page)) {
1116                                         clear_buffer_new(bh);
1117                                         set_buffer_uptodate(bh);
1118                                         mark_buffer_dirty(bh);
1119                                         continue;
1120                                 }
1121                                 if (block_end > to || block_start < from)
1122                                         zero_user_segments(page, to, block_end,
1123                                                            block_start, from);
1124                                 continue;
1125                         }
1126                 }
1127                 if (PageUptodate(page)) {
1128                         if (!buffer_uptodate(bh))
1129                                 set_buffer_uptodate(bh);
1130                         continue;
1131                 }
1132                 if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
1133                     !buffer_unwritten(bh) &&
1134                     (block_start < from || block_end > to)) {
1135                         ll_rw_block(READ, 1, &bh);
1136                         *wait_bh++ = bh;
1137                         decrypt = ext4_encrypted_inode(inode) &&
1138                                 S_ISREG(inode->i_mode);
1139                 }
1140         }
1141         /*
1142          * If we issued read requests, let them complete.
1143          */
1144         while (wait_bh > wait) {
1145                 wait_on_buffer(*--wait_bh);
1146                 if (!buffer_uptodate(*wait_bh))
1147                         err = -EIO;
1148         }
1149         if (unlikely(err))
1150                 page_zero_new_buffers(page, from, to);
1151         else if (decrypt)
1152                 err = ext4_decrypt(page);
1153         return err;
1154 }
1155 #endif
1156 
1157 static int ext4_write_begin(struct file *file, struct address_space *mapping,
1158                             loff_t pos, unsigned len, unsigned flags,
1159                             struct page **pagep, void **fsdata)
1160 {
1161         struct inode *inode = mapping->host;
1162         int ret, needed_blocks;
1163         handle_t *handle;
1164         int retries = 0;
1165         struct page *page;
1166         pgoff_t index;
1167         unsigned from, to;
1168 
1169         trace_ext4_write_begin(inode, pos, len, flags);
1170         /*
1171          * Reserve one block more for addition to orphan list in case
1172          * we allocate blocks but write fails for some reason
1173          */
1174         needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
1175         index = pos >> PAGE_SHIFT;
1176         from = pos & (PAGE_SIZE - 1);
1177         to = from + len;
1178 
1179         if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
1180                 ret = ext4_try_to_write_inline_data(mapping, inode, pos, len,
1181                                                     flags, pagep);
1182                 if (ret < 0)
1183                         return ret;
1184                 if (ret == 1)
1185                         return 0;
1186         }
1187 
1188         /*
1189          * grab_cache_page_write_begin() can take a long time if the
1190          * system is thrashing due to memory pressure, or if the page
1191          * is being written back.  So grab it first before we start
1192          * the transaction handle.  This also allows us to allocate
1193          * the page (if needed) without using GFP_NOFS.
1194          */
1195 retry_grab:
1196         page = grab_cache_page_write_begin(mapping, index, flags);
1197         if (!page)
1198                 return -ENOMEM;
1199         unlock_page(page);
1200 
1201 retry_journal:
1202         handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, needed_blocks);
1203         if (IS_ERR(handle)) {
1204                 put_page(page);
1205                 return PTR_ERR(handle);
1206         }
1207 
1208         lock_page(page);
1209         if (page->mapping != mapping) {
1210                 /* The page got truncated from under us */
1211                 unlock_page(page);
1212                 put_page(page);
1213                 ext4_journal_stop(handle);
1214                 goto retry_grab;
1215         }
1216         /* In case writeback began while the page was unlocked */
1217         wait_for_stable_page(page);
1218 
1219 #ifdef CONFIG_EXT4_FS_ENCRYPTION
1220         if (ext4_should_dioread_nolock(inode))
1221                 ret = ext4_block_write_begin(page, pos, len,
1222                                              ext4_get_block_unwritten);
1223         else
1224                 ret = ext4_block_write_begin(page, pos, len,
1225                                              ext4_get_block);
1226 #else
1227         if (ext4_should_dioread_nolock(inode))
1228                 ret = __block_write_begin(page, pos, len,
1229                                           ext4_get_block_unwritten);
1230         else
1231                 ret = __block_write_begin(page, pos, len, ext4_get_block);
1232 #endif
1233         if (!ret && ext4_should_journal_data(inode)) {
1234                 ret = ext4_walk_page_buffers(handle, page_buffers(page),
1235                                              from, to, NULL,
1236                                              do_journal_get_write_access);
1237         }
1238 
1239         if (ret) {
1240                 unlock_page(page);
1241                 /*
1242                  * __block_write_begin may have instantiated a few blocks
1243                  * outside i_size.  Trim these off again. Don't need
1244                  * i_size_read because we hold i_mutex.
1245                  *
1246                  * Add inode to orphan list in case we crash before
1247                  * truncate finishes
1248                  */
1249                 if (pos + len > inode->i_size && ext4_can_truncate(inode))
1250                         ext4_orphan_add(handle, inode);
1251 
1252                 ext4_journal_stop(handle);
1253                 if (pos + len > inode->i_size) {
1254                         ext4_truncate_failed_write(inode);
1255                         /*
1256                          * If truncate failed early the inode might
1257                          * still be on the orphan list; we need to
1258                          * make sure the inode is removed from the
1259                          * orphan list in that case.
1260                          */
1261                         if (inode->i_nlink)
1262                                 ext4_orphan_del(NULL, inode);
1263                 }
1264 
1265                 if (ret == -ENOSPC &&
1266                     ext4_should_retry_alloc(inode->i_sb, &retries))
1267                         goto retry_journal;
1268                 put_page(page);
1269                 return ret;
1270         }
1271         *pagep = page;
1272         return ret;
1273 }
1274 
1275 /* For write_end() in data=journal mode */
1276 static int write_end_fn(handle_t *handle, struct buffer_head *bh)
1277 {
1278         int ret;
1279         if (!buffer_mapped(bh) || buffer_freed(bh))
1280                 return 0;
1281         set_buffer_uptodate(bh);
1282         ret = ext4_handle_dirty_metadata(handle, NULL, bh);
1283         clear_buffer_meta(bh);
1284         clear_buffer_prio(bh);
1285         return ret;
1286 }
1287 
1288 /*
1289  * We need to pick up the new inode size which generic_commit_write gave us
1290  * `file' can be NULL - eg, when called from page_symlink().
1291  *
1292  * ext4 never places buffers on inode->i_mapping->private_list.  metadata
1293  * buffers are managed internally.
1294  */
1295 static int ext4_write_end(struct file *file,
1296                           struct address_space *mapping,
1297                           loff_t pos, unsigned len, unsigned copied,
1298                           struct page *page, void *fsdata)
1299 {
1300         handle_t *handle = ext4_journal_current_handle();
1301         struct inode *inode = mapping->host;
1302         loff_t old_size = inode->i_size;
1303         int ret = 0, ret2;
1304         int i_size_changed = 0;
1305 
1306         trace_ext4_write_end(inode, pos, len, copied);
1307         if (ext4_has_inline_data(inode)) {
1308                 ret = ext4_write_inline_data_end(inode, pos, len,
1309                                                  copied, page);
1310                 if (ret < 0)
1311                         goto errout;
1312                 copied = ret;
1313         } else
1314                 copied = block_write_end(file, mapping, pos,
1315                                          len, copied, page, fsdata);
1316         /*
1317          * it's important to update i_size while still holding page lock:
1318          * page writeout could otherwise come in and zero beyond i_size.
1319          */
1320         i_size_changed = ext4_update_inode_size(inode, pos + copied);
1321         unlock_page(page);
1322         put_page(page);
1323 
1324         if (old_size < pos)
1325                 pagecache_isize_extended(inode, old_size, pos);
1326         /*
1327          * Don't mark the inode dirty under page lock. First, it unnecessarily
1328          * makes the holding time of page lock longer. Second, it forces lock
1329          * ordering of page lock and transaction start for journaling
1330          * filesystems.
1331          */
1332         if (i_size_changed)
1333                 ext4_mark_inode_dirty(handle, inode);
1334 
1335         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1336                 /* if we have allocated more blocks and copied
1337                  * less. We will have blocks allocated outside
1338                  * inode->i_size. So truncate them
1339                  */
1340                 ext4_orphan_add(handle, inode);
1341 errout:
1342         ret2 = ext4_journal_stop(handle);
1343         if (!ret)
1344                 ret = ret2;
1345 
1346         if (pos + len > inode->i_size) {
1347                 ext4_truncate_failed_write(inode);
1348                 /*
1349                  * If truncate failed early the inode might still be
1350                  * on the orphan list; we need to make sure the inode
1351                  * is removed from the orphan list in that case.
1352                  */
1353                 if (inode->i_nlink)
1354                         ext4_orphan_del(NULL, inode);
1355         }
1356 
1357         return ret ? ret : copied;
1358 }
1359 
1360 /*
1361  * This is a private version of page_zero_new_buffers() which doesn't
1362  * set the buffer to be dirty, since in data=journalled mode we need
1363  * to call ext4_handle_dirty_metadata() instead.
1364  */
1365 static void zero_new_buffers(struct page *page, unsigned from, unsigned to)
1366 {
1367         unsigned int block_start = 0, block_end;
1368         struct buffer_head *head, *bh;
1369 
1370         bh = head = page_buffers(page);
1371         do {
1372                 block_end = block_start + bh->b_size;
1373                 if (buffer_new(bh)) {
1374                         if (block_end > from && block_start < to) {
1375                                 if (!PageUptodate(page)) {
1376                                         unsigned start, size;
1377 
1378                                         start = max(from, block_start);
1379                                         size = min(to, block_end) - start;
1380 
1381                                         zero_user(page, start, size);
1382                                         set_buffer_uptodate(bh);
1383                                 }
1384                                 clear_buffer_new(bh);
1385                         }
1386                 }
1387                 block_start = block_end;
1388                 bh = bh->b_this_page;
1389         } while (bh != head);
1390 }
1391 
1392 static int ext4_journalled_write_end(struct file *file,
1393                                      struct address_space *mapping,
1394                                      loff_t pos, unsigned len, unsigned copied,
1395                                      struct page *page, void *fsdata)
1396 {
1397         handle_t *handle = ext4_journal_current_handle();
1398         struct inode *inode = mapping->host;
1399         loff_t old_size = inode->i_size;
1400         int ret = 0, ret2;
1401         int partial = 0;
1402         unsigned from, to;
1403         int size_changed = 0;
1404 
1405         trace_ext4_journalled_write_end(inode, pos, len, copied);
1406         from = pos & (PAGE_SIZE - 1);
1407         to = from + len;
1408 
1409         BUG_ON(!ext4_handle_valid(handle));
1410 
1411         if (ext4_has_inline_data(inode))
1412                 copied = ext4_write_inline_data_end(inode, pos, len,
1413                                                     copied, page);
1414         else {
1415                 if (copied < len) {
1416                         if (!PageUptodate(page))
1417                                 copied = 0;
1418                         zero_new_buffers(page, from+copied, to);
1419                 }
1420 
1421                 ret = ext4_walk_page_buffers(handle, page_buffers(page), from,
1422                                              to, &partial, write_end_fn);
1423                 if (!partial)
1424                         SetPageUptodate(page);
1425         }
1426         size_changed = ext4_update_inode_size(inode, pos + copied);
1427         ext4_set_inode_state(inode, EXT4_STATE_JDATA);
1428         EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
1429         unlock_page(page);
1430         put_page(page);
1431 
1432         if (old_size < pos)
1433                 pagecache_isize_extended(inode, old_size, pos);
1434 
1435         if (size_changed) {
1436                 ret2 = ext4_mark_inode_dirty(handle, inode);
1437                 if (!ret)
1438                         ret = ret2;
1439         }
1440 
1441         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1442                 /* if we have allocated more blocks and copied
1443                  * less. We will have blocks allocated outside
1444                  * inode->i_size. So truncate them
1445                  */
1446                 ext4_orphan_add(handle, inode);
1447 
1448         ret2 = ext4_journal_stop(handle);
1449         if (!ret)
1450                 ret = ret2;
1451         if (pos + len > inode->i_size) {
1452                 ext4_truncate_failed_write(inode);
1453                 /*
1454                  * If truncate failed early the inode might still be
1455                  * on the orphan list; we need to make sure the inode
1456                  * is removed from the orphan list in that case.
1457                  */
1458                 if (inode->i_nlink)
1459                         ext4_orphan_del(NULL, inode);
1460         }
1461 
1462         return ret ? ret : copied;
1463 }
1464 
1465 /*
1466  * Reserve space for a single cluster
1467  */
1468 static int ext4_da_reserve_space(struct inode *inode)
1469 {
1470         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1471         struct ext4_inode_info *ei = EXT4_I(inode);
1472         int ret;
1473 
1474         /*
1475          * We will charge metadata quota at writeout time; this saves
1476          * us from metadata over-estimation, though we may go over by
1477          * a small amount in the end.  Here we just reserve for data.
1478          */
1479         ret = dquot_reserve_block(inode, EXT4_C2B(sbi, 1));
1480         if (ret)
1481                 return ret;
1482 
1483         spin_lock(&ei->i_block_reservation_lock);
1484         if (ext4_claim_free_clusters(sbi, 1, 0)) {
1485                 spin_unlock(&ei->i_block_reservation_lock);
1486                 dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
1487                 return -ENOSPC;
1488         }
1489         ei->i_reserved_data_blocks++;
1490         trace_ext4_da_reserve_space(inode);
1491         spin_unlock(&ei->i_block_reservation_lock);
1492 
1493         return 0;       /* success */
1494 }
1495 
1496 static void ext4_da_release_space(struct inode *inode, int to_free)
1497 {
1498         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1499         struct ext4_inode_info *ei = EXT4_I(inode);
1500 
1501         if (!to_free)
1502                 return;         /* Nothing to release, exit */
1503 
1504         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1505 
1506         trace_ext4_da_release_space(inode, to_free);
1507         if (unlikely(to_free > ei->i_reserved_data_blocks)) {
1508                 /*
1509                  * if there aren't enough reserved blocks, then the
1510                  * counter is messed up somewhere.  Since this
1511                  * function is called from invalidate page, it's
1512                  * harmless to return without any action.
1513                  */
1514                 ext4_warning(inode->i_sb, "ext4_da_release_space: "
1515                          "ino %lu, to_free %d with only %d reserved "
1516                          "data blocks", inode->i_ino, to_free,
1517                          ei->i_reserved_data_blocks);
1518                 WARN_ON(1);
1519                 to_free = ei->i_reserved_data_blocks;
1520         }
1521         ei->i_reserved_data_blocks -= to_free;
1522 
1523         /* update fs dirty data blocks counter */
1524         percpu_counter_sub(&sbi->s_dirtyclusters_counter, to_free);
1525 
1526         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1527 
1528         dquot_release_reservation_block(inode, EXT4_C2B(sbi, to_free));
1529 }
1530 
1531 static void ext4_da_page_release_reservation(struct page *page,
1532                                              unsigned int offset,
1533                                              unsigned int length)
1534 {
1535         int to_release = 0, contiguous_blks = 0;
1536         struct buffer_head *head, *bh;
1537         unsigned int curr_off = 0;
1538         struct inode *inode = page->mapping->host;
1539         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1540         unsigned int stop = offset + length;
1541         int num_clusters;
1542         ext4_fsblk_t lblk;
1543 
1544         BUG_ON(stop > PAGE_SIZE || stop < length);
1545 
1546         head = page_buffers(page);
1547         bh = head;
1548         do {
1549                 unsigned int next_off = curr_off + bh->b_size;
1550 
1551                 if (next_off > stop)
1552                         break;
1553 
1554                 if ((offset <= curr_off) && (buffer_delay(bh))) {
1555                         to_release++;
1556                         contiguous_blks++;
1557                         clear_buffer_delay(bh);
1558                 } else if (contiguous_blks) {
1559                         lblk = page->index <<
1560                                (PAGE_SHIFT - inode->i_blkbits);
1561                         lblk += (curr_off >> inode->i_blkbits) -
1562                                 contiguous_blks;
1563                         ext4_es_remove_extent(inode, lblk, contiguous_blks);
1564                         contiguous_blks = 0;
1565                 }
1566                 curr_off = next_off;
1567         } while ((bh = bh->b_this_page) != head);
1568 
1569         if (contiguous_blks) {
1570                 lblk = page->index << (PAGE_SHIFT - inode->i_blkbits);
1571                 lblk += (curr_off >> inode->i_blkbits) - contiguous_blks;
1572                 ext4_es_remove_extent(inode, lblk, contiguous_blks);
1573         }
1574 
1575         /* If we have released all the blocks belonging to a cluster, then we
1576          * need to release the reserved space for that cluster. */
1577         num_clusters = EXT4_NUM_B2C(sbi, to_release);
1578         while (num_clusters > 0) {
1579                 lblk = (page->index << (PAGE_SHIFT - inode->i_blkbits)) +
1580                         ((num_clusters - 1) << sbi->s_cluster_bits);
1581                 if (sbi->s_cluster_ratio == 1 ||
1582                     !ext4_find_delalloc_cluster(inode, lblk))
1583                         ext4_da_release_space(inode, 1);
1584 
1585                 num_clusters--;
1586         }
1587 }
1588 
1589 /*
1590  * Delayed allocation stuff
1591  */
1592 
1593 struct mpage_da_data {
1594         struct inode *inode;
1595         struct writeback_control *wbc;
1596 
1597         pgoff_t first_page;     /* The first page to write */
1598         pgoff_t next_page;      /* Current page to examine */
1599         pgoff_t last_page;      /* Last page to examine */
1600         /*
1601          * Extent to map - this can be after first_page because that can be
1602          * fully mapped. We somewhat abuse m_flags to store whether the extent
1603          * is delalloc or unwritten.
1604          */
1605         struct ext4_map_blocks map;
1606         struct ext4_io_submit io_submit;        /* IO submission data */
1607 };
1608 
1609 static void mpage_release_unused_pages(struct mpage_da_data *mpd,
1610                                        bool invalidate)
1611 {
1612         int nr_pages, i;
1613         pgoff_t index, end;
1614         struct pagevec pvec;
1615         struct inode *inode = mpd->inode;
1616         struct address_space *mapping = inode->i_mapping;
1617 
1618         /* This is necessary when next_page == 0. */
1619         if (mpd->first_page >= mpd->next_page)
1620                 return;
1621 
1622         index = mpd->first_page;
1623         end   = mpd->next_page - 1;
1624         if (invalidate) {
1625                 ext4_lblk_t start, last;
1626                 start = index << (PAGE_SHIFT - inode->i_blkbits);
1627                 last = end << (PAGE_SHIFT - inode->i_blkbits);
1628                 ext4_es_remove_extent(inode, start, last - start + 1);
1629         }
1630 
1631         pagevec_init(&pvec, 0);
1632         while (index <= end) {
1633                 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
1634                 if (nr_pages == 0)
1635                         break;
1636                 for (i = 0; i < nr_pages; i++) {
1637                         struct page *page = pvec.pages[i];
1638                         if (page->index > end)
1639                                 break;
1640                         BUG_ON(!PageLocked(page));
1641                         BUG_ON(PageWriteback(page));
1642                         if (invalidate) {
1643                                 block_invalidatepage(page, 0, PAGE_SIZE);
1644                                 ClearPageUptodate(page);
1645                         }
1646                         unlock_page(page);
1647                 }
1648                 index = pvec.pages[nr_pages - 1]->index + 1;
1649                 pagevec_release(&pvec);
1650         }
1651 }
1652 
1653 static void ext4_print_free_blocks(struct inode *inode)
1654 {
1655         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1656         struct super_block *sb = inode->i_sb;
1657         struct ext4_inode_info *ei = EXT4_I(inode);
1658 
1659         ext4_msg(sb, KERN_CRIT, "Total free blocks count %lld",
1660                EXT4_C2B(EXT4_SB(inode->i_sb),
1661                         ext4_count_free_clusters(sb)));
1662         ext4_msg(sb, KERN_CRIT, "Free/Dirty block details");
1663         ext4_msg(sb, KERN_CRIT, "free_blocks=%lld",
1664                (long long) EXT4_C2B(EXT4_SB(sb),
1665                 percpu_counter_sum(&sbi->s_freeclusters_counter)));
1666         ext4_msg(sb, KERN_CRIT, "dirty_blocks=%lld",
1667                (long long) EXT4_C2B(EXT4_SB(sb),
1668                 percpu_counter_sum(&sbi->s_dirtyclusters_counter)));
1669         ext4_msg(sb, KERN_CRIT, "Block reservation details");
1670         ext4_msg(sb, KERN_CRIT, "i_reserved_data_blocks=%u",
1671                  ei->i_reserved_data_blocks);
1672         return;
1673 }
1674 
1675 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh)
1676 {
1677         return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh);
1678 }
1679 
1680 /*
1681  * This function is grabs code from the very beginning of
1682  * ext4_map_blocks, but assumes that the caller is from delayed write
1683  * time. This function looks up the requested blocks and sets the
1684  * buffer delay bit under the protection of i_data_sem.
1685  */
1686 static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
1687                               struct ext4_map_blocks *map,
1688                               struct buffer_head *bh)
1689 {
1690         struct extent_status es;
1691         int retval;
1692         sector_t invalid_block = ~((sector_t) 0xffff);
1693 #ifdef ES_AGGRESSIVE_TEST
1694         struct ext4_map_blocks orig_map;
1695 
1696         memcpy(&orig_map, map, sizeof(*map));
1697 #endif
1698 
1699         if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
1700                 invalid_block = ~0;
1701 
1702         map->m_flags = 0;
1703         ext_debug("ext4_da_map_blocks(): inode %lu, max_blocks %u,"
1704                   "logical block %lu\n", inode->i_ino, map->m_len,
1705                   (unsigned long) map->m_lblk);
1706 
1707         /* Lookup extent status tree firstly */
1708         if (ext4_es_lookup_extent(inode, iblock, &es)) {
1709                 if (ext4_es_is_hole(&es)) {
1710                         retval = 0;
1711                         down_read(&EXT4_I(inode)->i_data_sem);
1712                         goto add_delayed;
1713                 }
1714 
1715                 /*
1716                  * Delayed extent could be allocated by fallocate.
1717                  * So we need to check it.
1718                  */
1719                 if (ext4_es_is_delayed(&es) && !ext4_es_is_unwritten(&es)) {
1720                         map_bh(bh, inode->i_sb, invalid_block);
1721                         set_buffer_new(bh);
1722                         set_buffer_delay(bh);
1723                         return 0;
1724                 }
1725 
1726                 map->m_pblk = ext4_es_pblock(&es) + iblock - es.es_lblk;
1727                 retval = es.es_len - (iblock - es.es_lblk);
1728                 if (retval > map->m_len)
1729                         retval = map->m_len;
1730                 map->m_len = retval;
1731                 if (ext4_es_is_written(&es))
1732                         map->m_flags |= EXT4_MAP_MAPPED;
1733                 else if (ext4_es_is_unwritten(&es))
1734                         map->m_flags |= EXT4_MAP_UNWRITTEN;
1735                 else
1736                         BUG_ON(1);
1737 
1738 #ifdef ES_AGGRESSIVE_TEST
1739                 ext4_map_blocks_es_recheck(NULL, inode, map, &orig_map, 0);
1740 #endif
1741                 return retval;
1742         }
1743 
1744         /*
1745          * Try to see if we can get the block without requesting a new
1746          * file system block.
1747          */
1748         down_read(&EXT4_I(inode)->i_data_sem);
1749         if (ext4_has_inline_data(inode))
1750                 retval = 0;
1751         else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
1752                 retval = ext4_ext_map_blocks(NULL, inode, map, 0);
1753         else
1754                 retval = ext4_ind_map_blocks(NULL, inode, map, 0);
1755 
1756 add_delayed:
1757         if (retval == 0) {
1758                 int ret;
1759                 /*
1760                  * XXX: __block_prepare_write() unmaps passed block,
1761                  * is it OK?
1762                  */
1763                 /*
1764                  * If the block was allocated from previously allocated cluster,
1765                  * then we don't need to reserve it again. However we still need
1766                  * to reserve metadata for every block we're going to write.
1767                  */
1768                 if (EXT4_SB(inode->i_sb)->s_cluster_ratio == 1 ||
1769                     !ext4_find_delalloc_cluster(inode, map->m_lblk)) {
1770                         ret = ext4_da_reserve_space(inode);
1771                         if (ret) {
1772                                 /* not enough space to reserve */
1773                                 retval = ret;
1774                                 goto out_unlock;
1775                         }
1776                 }
1777 
1778                 ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
1779                                             ~0, EXTENT_STATUS_DELAYED);
1780                 if (ret) {
1781                         retval = ret;
1782                         goto out_unlock;
1783                 }
1784 
1785                 map_bh(bh, inode->i_sb, invalid_block);
1786                 set_buffer_new(bh);
1787                 set_buffer_delay(bh);
1788         } else if (retval > 0) {
1789                 int ret;
1790                 unsigned int status;
1791 
1792                 if (unlikely(retval != map->m_len)) {
1793                         ext4_warning(inode->i_sb,
1794                                      "ES len assertion failed for inode "
1795                                      "%lu: retval %d != map->m_len %d",
1796                                      inode->i_ino, retval, map->m_len);
1797                         WARN_ON(1);
1798                 }
1799 
1800                 status = map->m_flags & EXT4_MAP_UNWRITTEN ?
1801                                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
1802                 ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
1803                                             map->m_pblk, status);
1804                 if (ret != 0)
1805                         retval = ret;
1806         }
1807 
1808 out_unlock:
1809         up_read((&EXT4_I(inode)->i_data_sem));
1810 
1811         return retval;
1812 }
1813 
1814 /*
1815  * This is a special get_block_t callback which is used by
1816  * ext4_da_write_begin().  It will either return mapped block or
1817  * reserve space for a single block.
1818  *
1819  * For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
1820  * We also have b_blocknr = -1 and b_bdev initialized properly
1821  *
1822  * For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
1823  * We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
1824  * initialized properly.
1825  */
1826 int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
1827                            struct buffer_head *bh, int create)
1828 {
1829         struct ext4_map_blocks map;
1830         int ret = 0;
1831 
1832         BUG_ON(create == 0);
1833         BUG_ON(bh->b_size != inode->i_sb->s_blocksize);
1834 
1835         map.m_lblk = iblock;
1836         map.m_len = 1;
1837 
1838         /*
1839          * first, we need to know whether the block is allocated already
1840          * preallocated blocks are unmapped but should treated
1841          * the same as allocated blocks.
1842          */
1843         ret = ext4_da_map_blocks(inode, iblock, &map, bh);
1844         if (ret <= 0)
1845                 return ret;
1846 
1847         map_bh(bh, inode->i_sb, map.m_pblk);
1848         ext4_update_bh_state(bh, map.m_flags);
1849 
1850         if (buffer_unwritten(bh)) {
1851                 /* A delayed write to unwritten bh should be marked
1852                  * new and mapped.  Mapped ensures that we don't do
1853                  * get_block multiple times when we write to the same
1854                  * offset and new ensures that we do proper zero out
1855                  * for partial write.
1856                  */
1857                 set_buffer_new(bh);
1858                 set_buffer_mapped(bh);
1859         }
1860         return 0;
1861 }
1862 
1863 static int bget_one(handle_t *handle, struct buffer_head *bh)
1864 {
1865         get_bh(bh);
1866         return 0;
1867 }
1868 
1869 static int bput_one(handle_t *handle, struct buffer_head *bh)
1870 {
1871         put_bh(bh);
1872         return 0;
1873 }
1874 
1875 static int __ext4_journalled_writepage(struct page *page,
1876                                        unsigned int len)
1877 {
1878         struct address_space *mapping = page->mapping;
1879         struct inode *inode = mapping->host;
1880         struct buffer_head *page_bufs = NULL;
1881         handle_t *handle = NULL;
1882         int ret = 0, err = 0;
1883         int inline_data = ext4_has_inline_data(inode);
1884         struct buffer_head *inode_bh = NULL;
1885 
1886         ClearPageChecked(page);
1887 
1888         if (inline_data) {
1889                 BUG_ON(page->index != 0);
1890                 BUG_ON(len > ext4_get_max_inline_size(inode));
1891                 inode_bh = ext4_journalled_write_inline_data(inode, len, page);
1892                 if (inode_bh == NULL)
1893                         goto out;
1894         } else {
1895                 page_bufs = page_buffers(page);
1896                 if (!page_bufs) {
1897                         BUG();
1898                         goto out;
1899                 }
1900                 ext4_walk_page_buffers(handle, page_bufs, 0, len,
1901                                        NULL, bget_one);
1902         }
1903         /*
1904          * We need to release the page lock before we start the
1905          * journal, so grab a reference so the page won't disappear
1906          * out from under us.
1907          */
1908         get_page(page);
1909         unlock_page(page);
1910 
1911         handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
1912                                     ext4_writepage_trans_blocks(inode));
1913         if (IS_ERR(handle)) {
1914                 ret = PTR_ERR(handle);
1915                 put_page(page);
1916                 goto out_no_pagelock;
1917         }
1918         BUG_ON(!ext4_handle_valid(handle));
1919 
1920         lock_page(page);
1921         put_page(page);
1922         if (page->mapping != mapping) {
1923                 /* The page got truncated from under us */
1924                 ext4_journal_stop(handle);
1925                 ret = 0;
1926                 goto out;
1927         }
1928 
1929         if (inline_data) {
1930                 BUFFER_TRACE(inode_bh, "get write access");
1931                 ret = ext4_journal_get_write_access(handle, inode_bh);
1932 
1933                 err = ext4_handle_dirty_metadata(handle, inode, inode_bh);
1934 
1935         } else {
1936                 ret = ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL,
1937                                              do_journal_get_write_access);
1938 
1939                 err = ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL,
1940                                              write_end_fn);
1941         }
1942         if (ret == 0)
1943                 ret = err;
1944         EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
1945         err = ext4_journal_stop(handle);
1946         if (!ret)
1947                 ret = err;
1948 
1949         if (!ext4_has_inline_data(inode))
1950                 ext4_walk_page_buffers(NULL, page_bufs, 0, len,
1951                                        NULL, bput_one);
1952         ext4_set_inode_state(inode, EXT4_STATE_JDATA);
1953 out:
1954         unlock_page(page);
1955 out_no_pagelock:
1956         brelse(inode_bh);
1957         return ret;
1958 }
1959 
1960 /*
1961  * Note that we don't need to start a transaction unless we're journaling data
1962  * because we should have holes filled from ext4_page_mkwrite(). We even don't
1963  * need to file the inode to the transaction's list in ordered mode because if
1964  * we are writing back data added by write(), the inode is already there and if
1965  * we are writing back data modified via mmap(), no one guarantees in which
1966  * transaction the data will hit the disk. In case we are journaling data, we
1967  * cannot start transaction directly because transaction start ranks above page
1968  * lock so we have to do some magic.
1969  *
1970  * This function can get called via...
1971  *   - ext4_writepages after taking page lock (have journal handle)
1972  *   - journal_submit_inode_data_buffers (no journal handle)
1973  *   - shrink_page_list via the kswapd/direct reclaim (no journal handle)
1974  *   - grab_page_cache when doing write_begin (have journal handle)
1975  *
1976  * We don't do any block allocation in this function. If we have page with
1977  * multiple blocks we need to write those buffer_heads that are mapped. This
1978  * is important for mmaped based write. So if we do with blocksize 1K
1979  * truncate(f, 1024);
1980  * a = mmap(f, 0, 4096);
1981  * a[0] = 'a';
1982  * truncate(f, 4096);
1983  * we have in the page first buffer_head mapped via page_mkwrite call back
1984  * but other buffer_heads would be unmapped but dirty (dirty done via the
1985  * do_wp_page). So writepage should write the first block. If we modify
1986  * the mmap area beyond 1024 we will again get a page_fault and the
1987  * page_mkwrite callback will do the block allocation and mark the
1988  * buffer_heads mapped.
1989  *
1990  * We redirty the page if we have any buffer_heads that is either delay or
1991  * unwritten in the page.
1992  *
1993  * We can get recursively called as show below.
1994  *
1995  *      ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
1996  *              ext4_writepage()
1997  *
1998  * But since we don't do any block allocation we should not deadlock.
1999  * Page also have the dirty flag cleared so we don't get recurive page_lock.
2000  */
2001 static int ext4_writepage(struct page *page,
2002                           struct writeback_control *wbc)
2003 {
2004         int ret = 0;
2005         loff_t size;
2006         unsigned int len;
2007         struct buffer_head *page_bufs = NULL;
2008         struct inode *inode = page->mapping->host;
2009         struct ext4_io_submit io_submit;
2010         bool keep_towrite = false;
2011 
2012         trace_ext4_writepage(page);
2013         size = i_size_read(inode);
2014         if (page->index == size >> PAGE_SHIFT)
2015                 len = size & ~PAGE_MASK;
2016         else
2017                 len = PAGE_SIZE;
2018 
2019         page_bufs = page_buffers(page);
2020         /*
2021          * We cannot do block allocation or other extent handling in this
2022          * function. If there are buffers needing that, we have to redirty
2023          * the page. But we may reach here when we do a journal commit via
2024          * journal_submit_inode_data_buffers() and in that case we must write
2025          * allocated buffers to achieve data=ordered mode guarantees.
2026          *
2027          * Also, if there is only one buffer per page (the fs block
2028          * size == the page size), if one buffer needs block
2029          * allocation or needs to modify the extent tree to clear the
2030          * unwritten flag, we know that the page can't be written at
2031          * all, so we might as well refuse the write immediately.
2032          * Unfortunately if the block size != page size, we can't as
2033          * easily detect this case using ext4_walk_page_buffers(), but
2034          * for the extremely common case, this is an optimization that
2035          * skips a useless round trip through ext4_bio_write_page().
2036          */
2037         if (ext4_walk_page_buffers(NULL, page_bufs, 0, len, NULL,
2038                                    ext4_bh_delay_or_unwritten)) {
2039                 redirty_page_for_writepage(wbc, page);
2040                 if ((current->flags & PF_MEMALLOC) ||
2041                     (inode->i_sb->s_blocksize == PAGE_SIZE)) {
2042                         /*
2043                          * For memory cleaning there's no point in writing only
2044                          * some buffers. So just bail out. Warn if we came here
2045                          * from direct reclaim.
2046                          */
2047                         WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD))
2048                                                         == PF_MEMALLOC);
2049                         unlock_page(page);
2050                         return 0;
2051                 }
2052                 keep_towrite = true;
2053         }
2054 
2055         if (PageChecked(page) && ext4_should_journal_data(inode))
2056                 /*
2057                  * It's mmapped pagecache.  Add buffers and journal it.  There
2058                  * doesn't seem much point in redirtying the page here.
2059                  */
2060                 return __ext4_journalled_writepage(page, len);
2061 
2062         ext4_io_submit_init(&io_submit, wbc);
2063         io_submit.io_end = ext4_init_io_end(inode, GFP_NOFS);
2064         if (!io_submit.io_end) {
2065                 redirty_page_for_writepage(wbc, page);
2066                 unlock_page(page);
2067                 return -ENOMEM;
2068         }
2069         ret = ext4_bio_write_page(&io_submit, page, len, wbc, keep_towrite);
2070         ext4_io_submit(&io_submit);
2071         /* Drop io_end reference we got from init */
2072         ext4_put_io_end_defer(io_submit.io_end);
2073         return ret;
2074 }
2075 
2076 static int mpage_submit_page(struct mpage_da_data *mpd, struct page *page)
2077 {
2078         int len;
2079         loff_t size = i_size_read(mpd->inode);
2080         int err;
2081 
2082         BUG_ON(page->index != mpd->first_page);
2083         if (page->index == size >> PAGE_SHIFT)
2084                 len = size & ~PAGE_MASK;
2085         else
2086                 len = PAGE_SIZE;
2087         clear_page_dirty_for_io(page);
2088         err = ext4_bio_write_page(&mpd->io_submit, page, len, mpd->wbc, false);
2089         if (!err)
2090                 mpd->wbc->nr_to_write--;
2091         mpd->first_page++;
2092 
2093         return err;
2094 }
2095 
2096 #define BH_FLAGS ((1 << BH_Unwritten) | (1 << BH_Delay))
2097 
2098 /*
2099  * mballoc gives us at most this number of blocks...
2100  * XXX: That seems to be only a limitation of ext4_mb_normalize_request().
2101  * The rest of mballoc seems to handle chunks up to full group size.
2102  */
2103 #define MAX_WRITEPAGES_EXTENT_LEN 2048
2104 
2105 /*
2106  * mpage_add_bh_to_extent - try to add bh to extent of blocks to map
2107  *
2108  * @mpd - extent of blocks
2109  * @lblk - logical number of the block in the file
2110  * @bh - buffer head we want to add to the extent
2111  *
2112  * The function is used to collect contig. blocks in the same state. If the
2113  * buffer doesn't require mapping for writeback and we haven't started the
2114  * extent of buffers to map yet, the function returns 'true' immediately - the
2115  * caller can write the buffer right away. Otherwise the function returns true
2116  * if the block has been added to the extent, false if the block couldn't be
2117  * added.
2118  */
2119 static bool mpage_add_bh_to_extent(struct mpage_da_data *mpd, ext4_lblk_t lblk,
2120                                    struct buffer_head *bh)
2121 {
2122         struct ext4_map_blocks *map = &mpd->map;
2123 
2124         /* Buffer that doesn't need mapping for writeback? */
2125         if (!buffer_dirty(bh) || !buffer_mapped(bh) ||
2126             (!buffer_delay(bh) && !buffer_unwritten(bh))) {
2127                 /* So far no extent to map => we write the buffer right away */
2128                 if (map->m_len == 0)
2129                         return true;
2130                 return false;
2131         }
2132 
2133         /* First block in the extent? */
2134         if (map->m_len == 0) {
2135                 map->m_lblk = lblk;
2136                 map->m_len = 1;
2137                 map->m_flags = bh->b_state & BH_FLAGS;
2138                 return true;
2139         }
2140 
2141         /* Don't go larger than mballoc is willing to allocate */
2142         if (map->m_len >= MAX_WRITEPAGES_EXTENT_LEN)
2143                 return false;
2144 
2145         /* Can we merge the block to our big extent? */
2146         if (lblk == map->m_lblk + map->m_len &&
2147             (bh->b_state & BH_FLAGS) == map->m_flags) {
2148                 map->m_len++;
2149                 return true;
2150         }
2151         return false;
2152 }
2153 
2154 /*
2155  * mpage_process_page_bufs - submit page buffers for IO or add them to extent
2156  *
2157  * @mpd - extent of blocks for mapping
2158  * @head - the first buffer in the page
2159  * @bh - buffer we should start processing from
2160  * @lblk - logical number of the block in the file corresponding to @bh
2161  *
2162  * Walk through page buffers from @bh upto @head (exclusive) and either submit
2163  * the page for IO if all buffers in this page were mapped and there's no
2164  * accumulated extent of buffers to map or add buffers in the page to the
2165  * extent of buffers to map. The function returns 1 if the caller can continue
2166  * by processing the next page, 0 if it should stop adding buffers to the
2167  * extent to map because we cannot extend it anymore. It can also return value
2168  * < 0 in case of error during IO submission.
2169  */
2170 static int mpage_process_page_bufs(struct mpage_da_data *mpd,
2171                                    struct buffer_head *head,
2172                                    struct buffer_head *bh,
2173                                    ext4_lblk_t lblk)
2174 {
2175         struct inode *inode = mpd->inode;
2176         int err;
2177         ext4_lblk_t blocks = (i_size_read(inode) + (1 << inode->i_blkbits) - 1)
2178                                                         >> inode->i_blkbits;
2179 
2180         do {
2181                 BUG_ON(buffer_locked(bh));
2182 
2183                 if (lblk >= blocks || !mpage_add_bh_to_extent(mpd, lblk, bh)) {
2184                         /* Found extent to map? */
2185                         if (mpd->map.m_len)
2186                                 return 0;
2187                         /* Everything mapped so far and we hit EOF */
2188                         break;
2189                 }
2190         } while (lblk++, (bh = bh->b_this_page) != head);
2191         /* So far everything mapped? Submit the page for IO. */
2192         if (mpd->map.m_len == 0) {
2193                 err = mpage_submit_page(mpd, head->b_page);
2194                 if (err < 0)
2195                         return err;
2196         }
2197         return lblk < blocks;
2198 }
2199 
2200 /*
2201  * mpage_map_buffers - update buffers corresponding to changed extent and
2202  *                     submit fully mapped pages for IO
2203  *
2204  * @mpd - description of extent to map, on return next extent to map
2205  *
2206  * Scan buffers corresponding to changed extent (we expect corresponding pages
2207  * to be already locked) and update buffer state according to new extent state.
2208  * We map delalloc buffers to their physical location, clear unwritten bits,
2209  * and mark buffers as uninit when we perform writes to unwritten extents
2210  * and do extent conversion after IO is finished. If the last page is not fully
2211  * mapped, we update @map to the next extent in the last page that needs
2212  * mapping. Otherwise we submit the page for IO.
2213  */
2214 static int mpage_map_and_submit_buffers(struct mpage_da_data *mpd)
2215 {
2216         struct pagevec pvec;
2217         int nr_pages, i;
2218         struct inode *inode = mpd->inode;
2219         struct buffer_head *head, *bh;
2220         int bpp_bits = PAGE_SHIFT - inode->i_blkbits;
2221         pgoff_t start, end;
2222         ext4_lblk_t lblk;
2223         sector_t pblock;
2224         int err;
2225 
2226         start = mpd->map.m_lblk >> bpp_bits;
2227         end = (mpd->map.m_lblk + mpd->map.m_len - 1) >> bpp_bits;
2228         lblk = start << bpp_bits;
2229         pblock = mpd->map.m_pblk;
2230 
2231         pagevec_init(&pvec, 0);
2232         while (start <= end) {
2233                 nr_pages = pagevec_lookup(&pvec, inode->i_mapping, start,
2234                                           PAGEVEC_SIZE);
2235                 if (nr_pages == 0)
2236                         break;
2237                 for (i = 0; i < nr_pages; i++) {
2238                         struct page *page = pvec.pages[i];
2239 
2240                         if (page->index > end)
2241                                 break;
2242                         /* Up to 'end' pages must be contiguous */
2243                         BUG_ON(page->index != start);
2244                         bh = head = page_buffers(page);
2245                         do {
2246                                 if (lblk < mpd->map.m_lblk)
2247                                         continue;
2248                                 if (lblk >= mpd->map.m_lblk + mpd->map.m_len) {
2249                                         /*
2250                                          * Buffer after end of mapped extent.
2251                                          * Find next buffer in the page to map.
2252                                          */
2253                                         mpd->map.m_len = 0;
2254                                         mpd->map.m_flags = 0;
2255                                         /*
2256                                          * FIXME: If dioread_nolock supports
2257                                          * blocksize < pagesize, we need to make
2258                                          * sure we add size mapped so far to
2259                                          * io_end->size as the following call
2260                                          * can submit the page for IO.
2261                                          */
2262                                         err = mpage_process_page_bufs(mpd, head,
2263                                                                       bh, lblk);
2264                                         pagevec_release(&pvec);
2265                                         if (err > 0)
2266                                                 err = 0;
2267                                         return err;
2268                                 }
2269                                 if (buffer_delay(bh)) {
2270                                         clear_buffer_delay(bh);
2271                                         bh->b_blocknr = pblock++;
2272                                 }
2273                                 clear_buffer_unwritten(bh);
2274                         } while (lblk++, (bh = bh->b_this_page) != head);
2275 
2276                         /*
2277                          * FIXME: This is going to break if dioread_nolock
2278                          * supports blocksize < pagesize as we will try to
2279                          * convert potentially unmapped parts of inode.
2280                          */
2281                         mpd->io_submit.io_end->size += PAGE_SIZE;
2282                         /* Page fully mapped - let IO run! */
2283                         err = mpage_submit_page(mpd, page);
2284                         if (err < 0) {
2285                                 pagevec_release(&pvec);
2286                                 return err;
2287                         }
2288                         start++;
2289                 }
2290                 pagevec_release(&pvec);
2291         }
2292         /* Extent fully mapped and matches with page boundary. We are done. */
2293         mpd->map.m_len = 0;
2294         mpd->map.m_flags = 0;
2295         return 0;
2296 }
2297 
2298 static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
2299 {
2300         struct inode *inode = mpd->inode;
2301         struct ext4_map_blocks *map = &mpd->map;
2302         int get_blocks_flags;
2303         int err, dioread_nolock;
2304 
2305         trace_ext4_da_write_pages_extent(inode, map);
2306         /*
2307          * Call ext4_map_blocks() to allocate any delayed allocation blocks, or
2308          * to convert an unwritten extent to be initialized (in the case
2309          * where we have written into one or more preallocated blocks).  It is
2310          * possible that we're going to need more metadata blocks than
2311          * previously reserved. However we must not fail because we're in
2312          * writeback and there is nothing we can do about it so it might result
2313          * in data loss.  So use reserved blocks to allocate metadata if
2314          * possible.
2315          *
2316          * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE if
2317          * the blocks in question are delalloc blocks.  This indicates
2318          * that the blocks and quotas has already been checked when
2319          * the data was copied into the page cache.
2320          */
2321         get_blocks_flags = EXT4_GET_BLOCKS_CREATE |
2322                            EXT4_GET_BLOCKS_METADATA_NOFAIL;
2323         dioread_nolock = ext4_should_dioread_nolock(inode);
2324         if (dioread_nolock)
2325                 get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
2326         if (map->m_flags & (1 << BH_Delay))
2327                 get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
2328 
2329         err = ext4_map_blocks(handle, inode, map, get_blocks_flags);
2330         if (err < 0)
2331                 return err;
2332         if (dioread_nolock && (map->m_flags & EXT4_MAP_UNWRITTEN)) {
2333                 if (!mpd->io_submit.io_end->handle &&
2334                     ext4_handle_valid(handle)) {
2335                         mpd->io_submit.io_end->handle = handle->h_rsv_handle;
2336                         handle->h_rsv_handle = NULL;
2337                 }
2338                 ext4_set_io_unwritten_flag(inode, mpd->io_submit.io_end);
2339         }
2340 
2341         BUG_ON(map->m_len == 0);
2342         if (map->m_flags & EXT4_MAP_NEW) {
2343                 struct block_device *bdev = inode->i_sb->s_bdev;
2344                 int i;
2345 
2346                 for (i = 0; i < map->m_len; i++)
2347                         unmap_underlying_metadata(bdev, map->m_pblk + i);
2348         }
2349         return 0;
2350 }
2351 
2352 /*
2353  * mpage_map_and_submit_extent - map extent starting at mpd->lblk of length
2354  *                               mpd->len and submit pages underlying it for IO
2355  *
2356  * @handle - handle for journal operations
2357  * @mpd - extent to map
2358  * @give_up_on_write - we set this to true iff there is a fatal error and there
2359  *                     is no hope of writing the data. The caller should discard
2360  *                     dirty pages to avoid infinite loops.
2361  *
2362  * The function maps extent starting at mpd->lblk of length mpd->len. If it is
2363  * delayed, blocks are allocated, if it is unwritten, we may need to convert
2364  * them to initialized or split the described range from larger unwritten
2365  * extent. Note that we need not map all the described range since allocation
2366  * can return less blocks or the range is covered by more unwritten extents. We
2367  * cannot map more because we are limited by reserved transaction credits. On
2368  * the other hand we always make sure that the last touched page is fully
2369  * mapped so that it can be written out (and thus forward progress is
2370  * guaranteed). After mapping we submit all mapped pages for IO.
2371  */
2372 static int mpage_map_and_submit_extent(handle_t *handle,
2373                                        struct mpage_da_data *mpd,
2374                                        bool *give_up_on_write)
2375 {
2376         struct inode *inode = mpd->inode;
2377         struct ext4_map_blocks *map = &mpd->map;
2378         int err;
2379         loff_t disksize;
2380         int progress = 0;
2381 
2382         mpd->io_submit.io_end->offset =
2383                                 ((loff_t)map->m_lblk) << inode->i_blkbits;
2384         do {
2385                 err = mpage_map_one_extent(handle, mpd);
2386                 if (err < 0) {
2387                         struct super_block *sb = inode->i_sb;
2388 
2389                         if (EXT4_SB(sb)->s_mount_flags & EXT4_MF_FS_ABORTED)
2390                                 goto invalidate_dirty_pages;
2391                         /*
2392                          * Let the uper layers retry transient errors.
2393                          * In the case of ENOSPC, if ext4_count_free_blocks()
2394                          * is non-zero, a commit should free up blocks.
2395                          */
2396                         if ((err == -ENOMEM) ||
2397                             (err == -ENOSPC && ext4_count_free_clusters(sb))) {
2398                                 if (progress)
2399                                         goto update_disksize;
2400                                 return err;
2401                         }
2402                         ext4_msg(sb, KERN_CRIT,
2403                                  "Delayed block allocation failed for "
2404                                  "inode %lu at logical offset %llu with"
2405                                  " max blocks %u with error %d",
2406                                  inode->i_ino,
2407                                  (unsigned long long)map->m_lblk,
2408                                  (unsigned)map->m_len, -err);
2409                         ext4_msg(sb, KERN_CRIT,
2410                                  "This should not happen!! Data will "
2411                                  "be lost\n");
2412                         if (err == -ENOSPC)
2413                                 ext4_print_free_blocks(inode);
2414                 invalidate_dirty_pages:
2415                         *give_up_on_write = true;
2416                         return err;
2417                 }
2418                 progress = 1;
2419                 /*
2420                  * Update buffer state, submit mapped pages, and get us new
2421                  * extent to map
2422                  */
2423                 err = mpage_map_and_submit_buffers(mpd);
2424                 if (err < 0)
2425                         goto update_disksize;
2426         } while (map->m_len);
2427 
2428 update_disksize:
2429         /*
2430          * Update on-disk size after IO is submitted.  Races with
2431          * truncate are avoided by checking i_size under i_data_sem.
2432          */
2433         disksize = ((loff_t)mpd->first_page) << PAGE_SHIFT;
2434         if (disksize > EXT4_I(inode)->i_disksize) {
2435                 int err2;
2436                 loff_t i_size;
2437 
2438                 down_write(&EXT4_I(inode)->i_data_sem);
2439                 i_size = i_size_read(inode);
2440                 if (disksize > i_size)
2441                         disksize = i_size;
2442                 if (disksize > EXT4_I(inode)->i_disksize)
2443                         EXT4_I(inode)->i_disksize = disksize;
2444                 err2 = ext4_mark_inode_dirty(handle, inode);
2445                 up_write(&EXT4_I(inode)->i_data_sem);
2446                 if (err2)
2447                         ext4_error(inode->i_sb,
2448                                    "Failed to mark inode %lu dirty",
2449                                    inode->i_ino);
2450                 if (!err)
2451                         err = err2;
2452         }
2453         return err;
2454 }
2455 
2456 /*
2457  * Calculate the total number of credits to reserve for one writepages
2458  * iteration. This is called from ext4_writepages(). We map an extent of
2459  * up to MAX_WRITEPAGES_EXTENT_LEN blocks and then we go on and finish mapping
2460  * the last partial page. So in total we can map MAX_WRITEPAGES_EXTENT_LEN +
2461  * bpp - 1 blocks in bpp different extents.
2462  */
2463 static int ext4_da_writepages_trans_blocks(struct inode *inode)
2464 {
2465         int bpp = ext4_journal_blocks_per_page(inode);
2466 
2467         return ext4_meta_trans_blocks(inode,
2468                                 MAX_WRITEPAGES_EXTENT_LEN + bpp - 1, bpp);
2469 }
2470 
2471 /*
2472  * mpage_prepare_extent_to_map - find & lock contiguous range of dirty pages
2473  *                               and underlying extent to map
2474  *
2475  * @mpd - where to look for pages
2476  *
2477  * Walk dirty pages in the mapping. If they are fully mapped, submit them for
2478  * IO immediately. When we find a page which isn't mapped we start accumulating
2479  * extent of buffers underlying these pages that needs mapping (formed by
2480  * either delayed or unwritten buffers). We also lock the pages containing
2481  * these buffers. The extent found is returned in @mpd structure (starting at
2482  * mpd->lblk with length mpd->len blocks).
2483  *
2484  * Note that this function can attach bios to one io_end structure which are
2485  * neither logically nor physically contiguous. Although it may seem as an
2486  * unnecessary complication, it is actually inevitable in blocksize < pagesize
2487  * case as we need to track IO to all buffers underlying a page in one io_end.
2488  */
2489 static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
2490 {
2491         struct address_space *mapping = mpd->inode->i_mapping;
2492         struct pagevec pvec;
2493         unsigned int nr_pages;
2494         long left = mpd->wbc->nr_to_write;
2495         pgoff_t index = mpd->first_page;
2496         pgoff_t end = mpd->last_page;
2497         int tag;
2498         int i, err = 0;
2499         int blkbits = mpd->inode->i_blkbits;
2500         ext4_lblk_t lblk;
2501         struct buffer_head *head;
2502 
2503         if (mpd->wbc->sync_mode == WB_SYNC_ALL || mpd->wbc->tagged_writepages)
2504                 tag = PAGECACHE_TAG_TOWRITE;
2505         else
2506                 tag = PAGECACHE_TAG_DIRTY;
2507 
2508         pagevec_init(&pvec, 0);
2509         mpd->map.m_len = 0;
2510         mpd->next_page = index;
2511         while (index <= end) {
2512                 nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
2513                               min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
2514                 if (nr_pages == 0)
2515                         goto out;
2516 
2517                 for (i = 0; i < nr_pages; i++) {
2518                         struct page *page = pvec.pages[i];
2519 
2520                         /*
2521                          * At this point, the page may be truncated or
2522                          * invalidated (changing page->mapping to NULL), or
2523                          * even swizzled back from swapper_space to tmpfs file
2524                          * mapping. However, page->index will not change
2525                          * because we have a reference on the page.
2526                          */
2527                         if (page->index > end)
2528                                 goto out;
2529 
2530                         /*
2531                          * Accumulated enough dirty pages? This doesn't apply
2532                          * to WB_SYNC_ALL mode. For integrity sync we have to
2533                          * keep going because someone may be concurrently
2534                          * dirtying pages, and we might have synced a lot of
2535                          * newly appeared dirty pages, but have not synced all
2536                          * of the old dirty pages.
2537                          */
2538                         if (mpd->wbc->sync_mode == WB_SYNC_NONE && left <= 0)
2539                                 goto out;
2540 
2541                         /* If we can't merge this page, we are done. */
2542                         if (mpd->map.m_len > 0 && mpd->next_page != page->index)
2543                                 goto out;
2544 
2545                         lock_page(page);
2546                         /*
2547                          * If the page is no longer dirty, or its mapping no
2548                          * longer corresponds to inode we are writing (which
2549                          * means it has been truncated or invalidated), or the
2550                          * page is already under writeback and we are not doing
2551                          * a data integrity writeback, skip the page
2552                          */
2553                         if (!PageDirty(page) ||
2554                             (PageWriteback(page) &&
2555                              (mpd->wbc->sync_mode == WB_SYNC_NONE)) ||
2556                             unlikely(page->mapping != mapping)) {
2557                                 unlock_page(page);
2558                                 continue;
2559                         }
2560 
2561                         wait_on_page_writeback(page);
2562                         BUG_ON(PageWriteback(page));
2563 
2564                         if (mpd->map.m_len == 0)
2565                                 mpd->first_page = page->index;
2566                         mpd->next_page = page->index + 1;
2567                         /* Add all dirty buffers to mpd */
2568                         lblk = ((ext4_lblk_t)page->index) <<
2569                                 (PAGE_SHIFT - blkbits);
2570                         head = page_buffers(page);
2571                         err = mpage_process_page_bufs(mpd, head, head, lblk);
2572                         if (err <= 0)
2573                                 goto out;
2574                         err = 0;
2575                         left--;
2576                 }
2577                 pagevec_release(&pvec);
2578                 cond_resched();
2579         }
2580         return 0;
2581 out:
2582         pagevec_release(&pvec);
2583         return err;
2584 }
2585 
2586 static int __writepage(struct page *page, struct writeback_control *wbc,
2587                        void *data)
2588 {
2589         struct address_space *mapping = data;
2590         int ret = ext4_writepage(page, wbc);
2591         mapping_set_error(mapping, ret);
2592         return ret;
2593 }
2594 
2595 static int ext4_writepages(struct address_space *mapping,
2596                            struct writeback_control *wbc)
2597 {
2598         pgoff_t writeback_index = 0;
2599         long nr_to_write = wbc->nr_to_write;
2600         int range_whole = 0;
2601         int cycled = 1;
2602         handle_t *handle = NULL;
2603         struct mpage_da_data mpd;
2604         struct inode *inode = mapping->host;
2605         int needed_blocks, rsv_blocks = 0, ret = 0;
2606         struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
2607         bool done;
2608         struct blk_plug plug;
2609         bool give_up_on_write = false;
2610 
2611         trace_ext4_writepages(inode, wbc);
2612 
2613         if (dax_mapping(mapping))
2614                 return dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev,
2615                                                    wbc);
2616 
2617         /*
2618          * No pages to write? This is mainly a kludge to avoid starting
2619          * a transaction for special inodes like journal inode on last iput()
2620          * because that could violate lock ordering on umount
2621          */
2622         if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
2623                 goto out_writepages;
2624 
2625         if (ext4_should_journal_data(inode)) {
2626                 struct blk_plug plug;
2627 
2628                 blk_start_plug(&plug);
2629                 ret = write_cache_pages(mapping, wbc, __writepage, mapping);
2630                 blk_finish_plug(&plug);
2631                 goto out_writepages;
2632         }
2633 
2634         /*
2635          * If the filesystem has aborted, it is read-only, so return
2636          * right away instead of dumping stack traces later on that
2637          * will obscure the real source of the problem.  We test
2638          * EXT4_MF_FS_ABORTED instead of sb->s_flag's MS_RDONLY because
2639          * the latter could be true if the filesystem is mounted
2640          * read-only, and in that case, ext4_writepages should
2641          * *never* be called, so if that ever happens, we would want
2642          * the stack trace.
2643          */
2644         if (unlikely(sbi->s_mount_flags & EXT4_MF_FS_ABORTED)) {
2645                 ret = -EROFS;
2646                 goto out_writepages;
2647         }
2648 
2649         if (ext4_should_dioread_nolock(inode)) {
2650                 /*
2651                  * We may need to convert up to one extent per block in
2652                  * the page and we may dirty the inode.
2653                  */
2654                 rsv_blocks = 1 + (PAGE_SIZE >> inode->i_blkbits);
2655         }
2656 
2657         /*
2658          * If we have inline data and arrive here, it means that
2659          * we will soon create the block for the 1st page, so
2660          * we'd better clear the inline data here.
2661          */
2662         if (ext4_has_inline_data(inode)) {
2663                 /* Just inode will be modified... */
2664                 handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
2665                 if (IS_ERR(handle)) {
2666                         ret = PTR_ERR(handle);
2667                         goto out_writepages;
2668                 }
2669                 BUG_ON(ext4_test_inode_state(inode,
2670                                 EXT4_STATE_MAY_INLINE_DATA));
2671                 ext4_destroy_inline_data(handle, inode);
2672                 ext4_journal_stop(handle);
2673         }
2674 
2675         if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2676                 range_whole = 1;
2677 
2678         if (wbc->range_cyclic) {
2679                 writeback_index = mapping->writeback_index;
2680                 if (writeback_index)
2681                         cycled = 0;
2682                 mpd.first_page = writeback_index;
2683                 mpd.last_page = -1;
2684         } else {
2685                 mpd.first_page = wbc->range_start >> PAGE_SHIFT;
2686                 mpd.last_page = wbc->range_end >> PAGE_SHIFT;
2687         }
2688 
2689         mpd.inode = inode;
2690         mpd.wbc = wbc;
2691         ext4_io_submit_init(&mpd.io_submit, wbc);
2692 retry:
2693         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
2694                 tag_pages_for_writeback(mapping, mpd.first_page, mpd.last_page);
2695         done = false;
2696         blk_start_plug(&plug);
2697         while (!done && mpd.first_page <= mpd.last_page) {
2698                 /* For each extent of pages we use new io_end */
2699                 mpd.io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
2700                 if (!mpd.io_submit.io_end) {
2701                         ret = -ENOMEM;
2702                         break;
2703                 }
2704 
2705                 /*
2706                  * We have two constraints: We find one extent to map and we
2707                  * must always write out whole page (makes a difference when
2708                  * blocksize < pagesize) so that we don't block on IO when we
2709                  * try to write out the rest of the page. Journalled mode is
2710                  * not supported by delalloc.
2711                  */
2712                 BUG_ON(ext4_should_journal_data(inode));
2713                 needed_blocks = ext4_da_writepages_trans_blocks(inode);
2714 
2715                 /* start a new transaction */
2716                 handle = ext4_journal_start_with_reserve(inode,
2717                                 EXT4_HT_WRITE_PAGE, needed_blocks, rsv_blocks);
2718                 if (IS_ERR(handle)) {
2719                         ret = PTR_ERR(handle);
2720                         ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
2721                                "%ld pages, ino %lu; err %d", __func__,
2722                                 wbc->nr_to_write, inode->i_ino, ret);
2723                         /* Release allocated io_end */
2724                         ext4_put_io_end(mpd.io_submit.io_end);
2725                         break;
2726                 }
2727 
2728                 trace_ext4_da_write_pages(inode, mpd.first_page, mpd.wbc);
2729                 ret = mpage_prepare_extent_to_map(&mpd);
2730                 if (!ret) {
2731                         if (mpd.map.m_len)
2732                                 ret = mpage_map_and_submit_extent(handle, &mpd,
2733                                         &give_up_on_write);
2734                         else {
2735                                 /*
2736                                  * We scanned the whole range (or exhausted
2737                                  * nr_to_write), submitted what was mapped and
2738                                  * didn't find anything needing mapping. We are
2739                                  * done.
2740                                  */
2741                                 done = true;
2742                         }
2743                 }
2744                 /*
2745                  * Caution: If the handle is synchronous,
2746                  * ext4_journal_stop() can wait for transaction commit
2747                  * to finish which may depend on writeback of pages to
2748                  * complete or on page lock to be released.  In that
2749                  * case, we have to wait until after after we have
2750                  * submitted all the IO, released page locks we hold,
2751                  * and dropped io_end reference (for extent conversion
2752                  * to be able to complete) before stopping the handle.
2753                  */
2754                 if (!ext4_handle_valid(handle) || handle->h_sync == 0) {
2755                         ext4_journal_stop(handle);
2756                         handle = NULL;
2757                 }
2758                 /* Submit prepared bio */
2759                 ext4_io_submit(&mpd.io_submit);
2760                 /* Unlock pages we didn't use */
2761                 mpage_release_unused_pages(&mpd, give_up_on_write);
2762                 /*
2763                  * Drop our io_end reference we got from init. We have
2764                  * to be careful and use deferred io_end finishing if
2765                  * we are still holding the transaction as we can
2766                  * release the last reference to io_end which may end
2767                  * up doing unwritten extent conversion.
2768                  */
2769                 if (handle) {
2770                         ext4_put_io_end_defer(mpd.io_submit.io_end);
2771                         ext4_journal_stop(handle);
2772                 } else
2773                         ext4_put_io_end(mpd.io_submit.io_end);
2774 
2775                 if (ret == -ENOSPC && sbi->s_journal) {
2776                         /*
2777                          * Commit the transaction which would
2778                          * free blocks released in the transaction
2779                          * and try again
2780                          */
2781                         jbd2_journal_force_commit_nested(sbi->s_journal);
2782                         ret = 0;
2783                         continue;
2784                 }
2785                 /* Fatal error - ENOMEM, EIO... */
2786                 if (ret)
2787                         break;
2788         }
2789         blk_finish_plug(&plug);
2790         if (!ret && !cycled && wbc->nr_to_write > 0) {
2791                 cycled = 1;
2792                 mpd.last_page = writeback_index - 1;
2793                 mpd.first_page = 0;
2794                 goto retry;
2795         }
2796 
2797         /* Update index */
2798         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
2799                 /*
2800                  * Set the writeback_index so that range_cyclic
2801                  * mode will write it back later
2802                  */
2803                 mapping->writeback_index = mpd.first_page;
2804 
2805 out_writepages:
2806         trace_ext4_writepages_result(inode, wbc, ret,
2807                                      nr_to_write - wbc->nr_to_write);
2808         return ret;
2809 }
2810 
2811 static int ext4_nonda_switch(struct super_block *sb)
2812 {
2813         s64 free_clusters, dirty_clusters;
2814         struct ext4_sb_info *sbi = EXT4_SB(sb);
2815 
2816         /*
2817          * switch to non delalloc mode if we are running low
2818          * on free block. The free block accounting via percpu
2819          * counters can get slightly wrong with percpu_counter_batch getting
2820          * accumulated on each CPU without updating global counters
2821          * Delalloc need an accurate free block accounting. So switch
2822          * to non delalloc when we are near to error range.
2823          */
2824         free_clusters =
2825                 percpu_counter_read_positive(&sbi->s_freeclusters_counter);
2826         dirty_clusters =
2827                 percpu_counter_read_positive(&sbi->s_dirtyclusters_counter);
2828         /*
2829          * Start pushing delalloc when 1/2 of free blocks are dirty.
2830          */
2831         if (dirty_clusters && (free_clusters < 2 * dirty_clusters))
2832                 try_to_writeback_inodes_sb(sb, WB_REASON_FS_FREE_SPACE);
2833 
2834         if (2 * free_clusters < 3 * dirty_clusters ||
2835             free_clusters < (dirty_clusters + EXT4_FREECLUSTERS_WATERMARK)) {
2836                 /*
2837                  * free block count is less than 150% of dirty blocks
2838                  * or free blocks is less than watermark
2839                  */
2840                 return 1;
2841         }
2842         return 0;
2843 }
2844 
2845 /* We always reserve for an inode update; the superblock could be there too */
2846 static int ext4_da_write_credits(struct inode *inode, loff_t pos, unsigned len)
2847 {
2848         if (likely(ext4_has_feature_large_file(inode->i_sb)))
2849                 return 1;
2850 
2851         if (pos + len <= 0x7fffffffULL)
2852                 return 1;
2853 
2854         /* We might need to update the superblock to set LARGE_FILE */
2855         return 2;
2856 }
2857 
2858 static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
2859                                loff_t pos, unsigned len, unsigned flags,
2860                                struct page **pagep, void **fsdata)
2861 {
2862         int ret, retries = 0;
2863         struct page *page;
2864         pgoff_t index;
2865         struct inode *inode = mapping->host;
2866         handle_t *handle;
2867 
2868         index = pos >> PAGE_SHIFT;
2869 
2870         if (ext4_nonda_switch(inode->i_sb)) {
2871                 *fsdata = (void *)FALL_BACK_TO_NONDELALLOC;
2872                 return ext4_write_begin(file, mapping, pos,
2873                                         len, flags, pagep, fsdata);
2874         }
2875         *fsdata = (void *)0;
2876         trace_ext4_da_write_begin(inode, pos, len, flags);
2877 
2878         if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
2879                 ret = ext4_da_write_inline_data_begin(mapping, inode,
2880                                                       pos, len, flags,
2881                                                       pagep, fsdata);
2882                 if (ret < 0)
2883                         return ret;
2884                 if (ret == 1)
2885                         return 0;
2886         }
2887 
2888         /*
2889          * grab_cache_page_write_begin() can take a long time if the
2890          * system is thrashing due to memory pressure, or if the page
2891          * is being written back.  So grab it first before we start
2892          * the transaction handle.  This also allows us to allocate
2893          * the page (if needed) without using GFP_NOFS.
2894          */
2895 retry_grab:
2896         page = grab_cache_page_write_begin(mapping, index, flags);
2897         if (!page)
2898                 return -ENOMEM;
2899         unlock_page(page);
2900 
2901         /*
2902          * With delayed allocation, we don't log the i_disksize update
2903          * if there is delayed block allocation. But we still need
2904          * to journalling the i_disksize update if writes to the end
2905          * of file which has an already mapped buffer.
2906          */
2907 retry_journal:
2908         handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
2909                                 ext4_da_write_credits(inode, pos, len));
2910         if (IS_ERR(handle)) {
2911                 put_page(page);
2912                 return PTR_ERR(handle);
2913         }
2914 
2915         lock_page(page);
2916         if (page->mapping != mapping) {
2917                 /* The page got truncated from under us */
2918                 unlock_page(page);
2919                 put_page(page);
2920                 ext4_journal_stop(handle);
2921                 goto retry_grab;
2922         }
2923         /* In case writeback began while the page was unlocked */
2924         wait_for_stable_page(page);
2925 
2926 #ifdef CONFIG_EXT4_FS_ENCRYPTION
2927         ret = ext4_block_write_begin(page, pos, len,
2928                                      ext4_da_get_block_prep);
2929 #else
2930         ret = __block_write_begin(page, pos, len, ext4_da_get_block_prep);
2931 #endif
2932         if (ret < 0) {
2933                 unlock_page(page);
2934                 ext4_journal_stop(handle);
2935                 /*
2936                  * block_write_begin may have instantiated a few blocks
2937                  * outside i_size.  Trim these off again. Don't need
2938                  * i_size_read because we hold i_mutex.
2939                  */
2940                 if (pos + len > inode->i_size)
2941                         ext4_truncate_failed_write(inode);
2942 
2943                 if (ret == -ENOSPC &&
2944                     ext4_should_retry_alloc(inode->i_sb, &retries))
2945                         goto retry_journal;
2946 
2947                 put_page(page);
2948                 return ret;
2949         }
2950 
2951         *pagep = page;
2952         return ret;
2953 }
2954 
2955 /*
2956  * Check if we should update i_disksize
2957  * when write to the end of file but not require block allocation
2958  */
2959 static int ext4_da_should_update_i_disksize(struct page *page,
2960                                             unsigned long offset)
2961 {
2962         struct buffer_head *bh;
2963         struct inode *inode = page->mapping->host;
2964         unsigned int idx;
2965         int i;
2966 
2967         bh = page_buffers(page);
2968         idx = offset >> inode->i_blkbits;
2969 
2970         for (i = 0; i < idx; i++)
2971                 bh = bh->b_this_page;
2972 
2973         if (!buffer_mapped(bh) || (buffer_delay(bh)) || buffer_unwritten(bh))
2974                 return 0;
2975         return 1;
2976 }
2977 
2978 static int ext4_da_write_end(struct file *file,
2979                              struct address_space *mapping,
2980                              loff_t pos, unsigned len, unsigned copied,
2981                              struct page *page, void *fsdata)
2982 {
2983         struct inode *inode = mapping->host;
2984         int ret = 0, ret2;
2985         handle_t *handle = ext4_journal_current_handle();
2986         loff_t new_i_size;
2987         unsigned long start, end;
2988         int write_mode = (int)(unsigned long)fsdata;
2989 
2990         if (write_mode == FALL_BACK_TO_NONDELALLOC)
2991                 return ext4_write_end(file, mapping, pos,
2992                                       len, copied, page, fsdata);
2993 
2994         trace_ext4_da_write_end(inode, pos, len, copied);
2995         start = pos & (PAGE_SIZE - 1);
2996         end = start + copied - 1;
2997 
2998         /*
2999          * generic_write_end() will run mark_inode_dirty() if i_size
3000          * changes.  So let's piggyback the i_disksize mark_inode_dirty
3001          * into that.
3002          */
3003         new_i_size = pos + copied;
3004         if (copied && new_i_size > EXT4_I(inode)->i_disksize) {
3005                 if (ext4_has_inline_data(inode) ||
3006                     ext4_da_should_update_i_disksize(page, end)) {
3007                         ext4_update_i_disksize(inode, new_i_size);
3008                         /* We need to mark inode dirty even if
3009                          * new_i_size is less that inode->i_size
3010                          * bu greater than i_disksize.(hint delalloc)
3011                          */
3012                         ext4_mark_inode_dirty(handle, inode);
3013                 }
3014         }
3015 
3016         if (write_mode != CONVERT_INLINE_DATA &&
3017             ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) &&
3018             ext4_has_inline_data(inode))
3019                 ret2 = ext4_da_write_inline_data_end(inode, pos, len, copied,
3020                                                      page);
3021         else
3022                 ret2 = generic_write_end(file, mapping, pos, len, copied,
3023                                                         page, fsdata);
3024 
3025         copied = ret2;
3026         if (ret2 < 0)
3027                 ret = ret2;
3028         ret2 = ext4_journal_stop(handle);
3029         if (!ret)
3030                 ret = ret2;
3031 
3032         return ret ? ret : copied;
3033 }
3034 
3035 static void ext4_da_invalidatepage(struct page *page, unsigned int offset,
3036                                    unsigned int length)
3037 {
3038         /*
3039          * Drop reserved blocks
3040          */
3041         BUG_ON(!PageLocked(page));
3042         if (!page_has_buffers(page))
3043                 goto out;
3044 
3045         ext4_da_page_release_reservation(page, offset, length);
3046 
3047 out:
3048         ext4_invalidatepage(page, offset, length);
3049 
3050         return;
3051 }
3052 
3053 /*
3054  * Force all delayed allocation blocks to be allocated for a given inode.
3055  */
3056 int ext4_alloc_da_blocks(struct inode *inode)
3057 {
3058         trace_ext4_alloc_da_blocks(inode);
3059 
3060         if (!EXT4_I(inode)->i_reserved_data_blocks)
3061                 return 0;
3062 
3063         /*
3064          * We do something simple for now.  The filemap_flush() will
3065          * also start triggering a write of the data blocks, which is
3066          * not strictly speaking necessary (and for users of
3067          * laptop_mode, not even desirable).  However, to do otherwise
3068          * would require replicating code paths in:
3069          *
3070          * ext4_writepages() ->
3071          *    write_cache_pages() ---> (via passed in callback function)
3072          *        __mpage_da_writepage() -->
3073          *           mpage_add_bh_to_extent()
3074          *           mpage_da_map_blocks()
3075          *
3076          * The problem is that write_cache_pages(), located in
3077          * mm/page-writeback.c, marks pages clean in preparation for
3078          * doing I/O, which is not desirable if we're not planning on
3079          * doing I/O at all.
3080          *
3081          * We could call write_cache_pages(), and then redirty all of
3082          * the pages by calling redirty_page_for_writepage() but that
3083          * would be ugly in the extreme.  So instead we would need to
3084          * replicate parts of the code in the above functions,
3085          * simplifying them because we wouldn't actually intend to
3086          * write out the pages, but rather only collect contiguous
3087          * logical block extents, call the multi-block allocator, and
3088          * then update the buffer heads with the block allocations.
3089          *
3090          * For now, though, we'll cheat by calling filemap_flush(),
3091          * which will map the blocks, and start the I/O, but not
3092          * actually wait for the I/O to complete.
3093          */
3094         return filemap_flush(inode->i_mapping);
3095 }
3096 
3097 /*
3098  * bmap() is special.  It gets used by applications such as lilo and by
3099  * the swapper to find the on-disk block of a specific piece of data.
3100  *
3101  * Naturally, this is dangerous if the block concerned is still in the
3102  * journal.  If somebody makes a swapfile on an ext4 data-journaling
3103  * filesystem and enables swap, then they may get a nasty shock when the
3104  * data getting swapped to that swapfile suddenly gets overwritten by
3105  * the original zero's written out previously to the journal and
3106  * awaiting writeback in the kernel's buffer cache.
3107  *
3108  * So, if we see any bmap calls here on a modified, data-journaled file,
3109  * take extra steps to flush any blocks which might be in the cache.
3110  */
3111 static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
3112 {
3113         struct inode *inode = mapping->host;
3114         journal_t *journal;
3115         int err;
3116 
3117         /*
3118          * We can get here for an inline file via the FIBMAP ioctl
3119          */
3120         if (ext4_has_inline_data(inode))
3121                 return 0;
3122 
3123         if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
3124                         test_opt(inode->i_sb, DELALLOC)) {
3125                 /*
3126                  * With delalloc we want to sync the file
3127                  * so that we can make sure we allocate
3128                  * blocks for file
3129                  */
3130                 filemap_write_and_wait(mapping);
3131         }
3132 
3133         if (EXT4_JOURNAL(inode) &&
3134             ext4_test_inode_state(inode, EXT4_STATE_JDATA)) {
3135                 /*
3136                  * This is a REALLY heavyweight approach, but the use of
3137                  * bmap on dirty files is expected to be extremely rare:
3138                  * only if we run lilo or swapon on a freshly made file
3139                  * do we expect this to happen.
3140                  *
3141                  * (bmap requires CAP_SYS_RAWIO so this does not
3142                  * represent an unprivileged user DOS attack --- we'd be
3143                  * in trouble if mortal users could trigger this path at
3144                  * will.)
3145                  *
3146                  * NB. EXT4_STATE_JDATA is not set on files other than
3147                  * regular files.  If somebody wants to bmap a directory
3148                  * or symlink and gets confused because the buffer
3149                  * hasn't yet been flushed to disk, they deserve
3150                  * everything they get.
3151                  */
3152 
3153                 ext4_clear_inode_state(inode, EXT4_STATE_JDATA);
3154                 journal = EXT4_JOURNAL(inode);
3155                 jbd2_journal_lock_updates(journal);
3156                 err = jbd2_journal_flush(journal);
3157                 jbd2_journal_unlock_updates(journal);
3158 
3159                 if (err)
3160                         return 0;
3161         }
3162 
3163         return generic_block_bmap(mapping, block, ext4_get_block);
3164 }
3165 
3166 static int ext4_readpage(struct file *file, struct page *page)
3167 {
3168         int ret = -EAGAIN;
3169         struct inode *inode = page->mapping->host;
3170 
3171         trace_ext4_readpage(page);
3172 
3173         if (ext4_has_inline_data(inode))
3174                 ret = ext4_readpage_inline(inode, page);
3175 
3176         if (ret == -EAGAIN)
3177                 return ext4_mpage_readpages(page->mapping, NULL, page, 1);
3178 
3179         return ret;
3180 }
3181 
3182 static int
3183 ext4_readpages(struct file *file, struct address_space *mapping,
3184                 struct list_head *pages, unsigned nr_pages)
3185 {
3186         struct inode *inode = mapping->host;
3187 
3188         /* If the file has inline data, no need to do readpages. */
3189         if (ext4_has_inline_data(inode))
3190                 return 0;
3191 
3192         return ext4_mpage_readpages(mapping, pages, NULL, nr_pages);
3193 }
3194 
3195 static void ext4_invalidatepage(struct page *page, unsigned int offset,
3196                                 unsigned int length)
3197 {
3198         trace_ext4_invalidatepage(page, offset, length);
3199 
3200         /* No journalling happens on data buffers when this function is used */
3201         WARN_ON(page_has_buffers(page) && buffer_jbd(page_buffers(page)));
3202 
3203         block_invalidatepage(page, offset, length);
3204 }
3205 
3206 static int __ext4_journalled_invalidatepage(struct page *page,
3207                                             unsigned int offset,
3208                                             unsigned int length)
3209 {
3210         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
3211 
3212         trace_ext4_journalled_invalidatepage(page, offset, length);
3213 
3214         /*
3215          * If it's a full truncate we just forget about the pending dirtying
3216          */
3217         if (offset == 0 && length == PAGE_SIZE)
3218                 ClearPageChecked(page);
3219 
3220         return jbd2_journal_invalidatepage(journal, page, offset, length);
3221 }
3222 
3223 /* Wrapper for aops... */
3224 static void ext4_journalled_invalidatepage(struct page *page,
3225                                            unsigned int offset,
3226                                            unsigned int length)
3227 {
3228         WARN_ON(__ext4_journalled_invalidatepage(page, offset, length) < 0);
3229 }
3230 
3231 static int ext4_releasepage(struct page *page, gfp_t wait)
3232 {
3233         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
3234 
3235         trace_ext4_releasepage(page);
3236 
3237         /* Page has dirty journalled data -> cannot release */
3238         if (PageChecked(page))
3239                 return 0;
3240         if (journal)
3241                 return jbd2_journal_try_to_free_buffers(journal, page, wait);
3242         else
3243                 return try_to_free_buffers(page);
3244 }
3245 
3246 #ifdef CONFIG_FS_DAX
3247 int ext4_dax_mmap_get_block(struct inode *inode, sector_t iblock,
3248                             struct buffer_head *bh_result, int create)
3249 {
3250         int ret, err;
3251         int credits;
3252         struct ext4_map_blocks map;
3253         handle_t *handle = NULL;
3254         int flags = 0;
3255 
3256         ext4_debug("ext4_dax_mmap_get_block: inode %lu, create flag %d\n",
3257                    inode->i_ino, create);
3258         map.m_lblk = iblock;
3259         map.m_len = bh_result->b_size >> inode->i_blkbits;
3260         credits = ext4_chunk_trans_blocks(inode, map.m_len);
3261         if (create) {
3262                 flags |= EXT4_GET_BLOCKS_PRE_IO | EXT4_GET_BLOCKS_CREATE_ZERO;
3263                 handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, credits);
3264                 if (IS_ERR(handle)) {
3265                         ret = PTR_ERR(handle);
3266                         return ret;
3267                 }
3268         }
3269 
3270         ret = ext4_map_blocks(handle, inode, &map, flags);
3271         if (create) {
3272                 err = ext4_journal_stop(handle);
3273                 if (ret >= 0 && err < 0)
3274                         ret = err;
3275         }
3276         if (ret <= 0)
3277                 goto out;
3278         if (map.m_flags & EXT4_MAP_UNWRITTEN) {
3279                 int err2;
3280 
3281                 /*
3282                  * We are protected by i_mmap_sem so we know block cannot go
3283                  * away from under us even though we dropped i_data_sem.
3284                  * Convert extent to written and write zeros there.
3285                  *
3286                  * Note: We may get here even when create == 0.
3287                  */
3288                 handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, credits);
3289                 if (IS_ERR(handle)) {
3290                         ret = PTR_ERR(handle);
3291                         goto out;
3292                 }
3293 
3294                 err = ext4_map_blocks(handle, inode, &map,
3295                       EXT4_GET_BLOCKS_CONVERT | EXT4_GET_BLOCKS_CREATE_ZERO);
3296                 if (err < 0)
3297                         ret = err;
3298                 err2 = ext4_journal_stop(handle);
3299                 if (err2 < 0 && ret > 0)
3300                         ret = err2;
3301         }
3302 out:
3303         WARN_ON_ONCE(ret == 0 && create);
3304         if (ret > 0) {
3305                 map_bh(bh_result, inode->i_sb, map.m_pblk);
3306                 /*
3307                  * At least for now we have to clear BH_New so that DAX code
3308                  * doesn't attempt to zero blocks again in a racy way.
3309                  */
3310                 map.m_flags &= ~EXT4_MAP_NEW;
3311                 ext4_update_bh_state(bh_result, map.m_flags);
3312                 bh_result->b_size = map.m_len << inode->i_blkbits;
3313                 ret = 0;
3314         }
3315         return ret;
3316 }
3317 #endif
3318 
3319 static int ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
3320                             ssize_t size, void *private)
3321 {
3322         ext4_io_end_t *io_end = private;
3323 
3324         /* if not async direct IO just return */
3325         if (!io_end)
3326                 return 0;
3327 
3328         ext_debug("ext4_end_io_dio(): io_end 0x%p "
3329                   "for inode %lu, iocb 0x%p, offset %llu, size %zd\n",
3330                   io_end, io_end->inode->i_ino, iocb, offset, size);
3331 
3332         /*
3333          * Error during AIO DIO. We cannot convert unwritten extents as the
3334          * data was not written. Just clear the unwritten flag and drop io_end.
3335          */
3336         if (size <= 0) {
3337                 ext4_clear_io_unwritten_flag(io_end);
3338                 size = 0;
3339         }
3340         io_end->offset = offset;
3341         io_end->size = size;
3342         ext4_put_io_end(io_end);
3343 
3344         return 0;
3345 }
3346 
3347 /*
3348  * For ext4 extent files, ext4 will do direct-io write to holes,
3349  * preallocated extents, and those write extend the file, no need to
3350  * fall back to buffered IO.
3351  *
3352  * For holes, we fallocate those blocks, mark them as unwritten
3353  * If those blocks were preallocated, we mark sure they are split, but
3354  * still keep the range to write as unwritten.
3355  *
3356  * The unwritten extents will be converted to written when DIO is completed.
3357  * For async direct IO, since the IO may still pending when return, we
3358  * set up an end_io call back function, which will do the conversion
3359  * when async direct IO completed.
3360  *
3361  * If the O_DIRECT write will extend the file then add this inode to the
3362  * orphan list.  So recovery will truncate it back to the original size
3363  * if the machine crashes during the write.
3364  *
3365  */
3366 static ssize_t ext4_ext_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
3367                                   loff_t offset)
3368 {
3369         struct file *file = iocb->ki_filp;
3370         struct inode *inode = file->f_mapping->host;
3371         ssize_t ret;
3372         size_t count = iov_iter_count(iter);
3373         int overwrite = 0;
3374         get_block_t *get_block_func = NULL;
3375         int dio_flags = 0;
3376         loff_t final_size = offset + count;
3377 
3378         /* Use the old path for reads and writes beyond i_size. */
3379         if (iov_iter_rw(iter) != WRITE || final_size > inode->i_size)
3380                 return ext4_ind_direct_IO(iocb, iter, offset);
3381 
3382         BUG_ON(iocb->private == NULL);
3383 
3384         /*
3385          * Make all waiters for direct IO properly wait also for extent
3386          * conversion. This also disallows race between truncate() and
3387          * overwrite DIO as i_dio_count needs to be incremented under i_mutex.
3388          */
3389         if (iov_iter_rw(iter) == WRITE)
3390                 inode_dio_begin(inode);
3391 
3392         /* If we do a overwrite dio, i_mutex locking can be released */
3393         overwrite = *((int *)iocb->private);
3394 
3395         if (overwrite)
3396                 inode_unlock(inode);
3397 
3398         /*
3399          * We could direct write to holes and fallocate.
3400          *
3401          * Allocated blocks to fill the hole are marked as unwritten to prevent
3402          * parallel buffered read to expose the stale data before DIO complete
3403          * the data IO.
3404          *
3405          * As to previously fallocated extents, ext4 get_block will just simply
3406          * mark the buffer mapped but still keep the extents unwritten.
3407          *
3408          * For non AIO case, we will convert those unwritten extents to written
3409          * after return back from blockdev_direct_IO. That way we save us from
3410          * allocating io_end structure and also the overhead of offloading
3411          * the extent convertion to a workqueue.
3412          *
3413          * For async DIO, the conversion needs to be deferred when the
3414          * IO is completed. The ext4 end_io callback function will be
3415          * called to take care of the conversion work.  Here for async
3416          * case, we allocate an io_end structure to hook to the iocb.
3417          */
3418         iocb->private = NULL;
3419         if (overwrite)
3420                 get_block_func = ext4_dio_get_block_overwrite;
3421         else if (is_sync_kiocb(iocb)) {
3422                 get_block_func = ext4_dio_get_block_unwritten_sync;
3423                 dio_flags = DIO_LOCKING;
3424         } else {
3425                 get_block_func = ext4_dio_get_block_unwritten_async;
3426                 dio_flags = DIO_LOCKING;
3427         }
3428 #ifdef CONFIG_EXT4_FS_ENCRYPTION
3429         BUG_ON(ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode));
3430 #endif
3431         if (IS_DAX(inode))
3432                 ret = dax_do_io(iocb, inode, iter, offset, get_block_func,
3433                                 ext4_end_io_dio, dio_flags);
3434         else
3435                 ret = __blockdev_direct_IO(iocb, inode,
3436                                            inode->i_sb->s_bdev, iter, offset,
3437                                            get_block_func,
3438                                            ext4_end_io_dio, NULL, dio_flags);
3439 
3440         if (ret > 0 && !overwrite && ext4_test_inode_state(inode,
3441                                                 EXT4_STATE_DIO_UNWRITTEN)) {
3442                 int err;
3443                 /*
3444                  * for non AIO case, since the IO is already
3445                  * completed, we could do the conversion right here
3446                  */
3447                 err = ext4_convert_unwritten_extents(NULL, inode,
3448                                                      offset, ret);
3449                 if (err < 0)
3450                         ret = err;
3451                 ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
3452         }
3453 
3454         if (iov_iter_rw(iter) == WRITE)
3455                 inode_dio_end(inode);
3456         /* take i_mutex locking again if we do a ovewrite dio */
3457         if (overwrite)
3458                 inode_lock(inode);
3459 
3460         return ret;
3461 }
3462 
3463 static ssize_t ext4_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
3464                               loff_t offset)
3465 {
3466         struct file *file = iocb->ki_filp;
3467         struct inode *inode = file->f_mapping->host;
3468         size_t count = iov_iter_count(iter);
3469         ssize_t ret;
3470 
3471 #ifdef CONFIG_EXT4_FS_ENCRYPTION
3472         if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode))
3473                 return 0;
3474 #endif
3475 
3476         /*
3477          * If we are doing data journalling we don't support O_DIRECT
3478          */
3479         if (ext4_should_journal_data(inode))
3480                 return 0;
3481 
3482         /* Let buffer I/O handle the inline data case. */
3483         if (ext4_has_inline_data(inode))
3484                 return 0;
3485 
3486         trace_ext4_direct_IO_enter(inode, offset, count, iov_iter_rw(iter));
3487         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
3488                 ret = ext4_ext_direct_IO(iocb, iter, offset);
3489         else
3490                 ret = ext4_ind_direct_IO(iocb, iter, offset);
3491         trace_ext4_direct_IO_exit(inode, offset, count, iov_iter_rw(iter), ret);
3492         return ret;
3493 }
3494 
3495 /*
3496  * Pages can be marked dirty completely asynchronously from ext4's journalling
3497  * activity.  By filemap_sync_pte(), try_to_unmap_one(), etc.  We cannot do
3498  * much here because ->set_page_dirty is called under VFS locks.  The page is
3499  * not necessarily locked.
3500  *
3501  * We cannot just dirty the page and leave attached buffers clean, because the
3502  * buffers' dirty state is "definitive".  We cannot just set the buffers dirty
3503  * or jbddirty because all the journalling code will explode.
3504  *
3505  * So what we do is to mark the page "pending dirty" and next time writepage
3506  * is called, propagate that into the buffers appropriately.
3507  */
3508 static int ext4_journalled_set_page_dirty(struct page *page)
3509 {
3510         SetPageChecked(page);
3511         return __set_page_dirty_nobuffers(page);
3512 }
3513 
3514 static const struct address_space_operations ext4_aops = {
3515         .readpage               = ext4_readpage,
3516         .readpages              = ext4_readpages,
3517         .writepage              = ext4_writepage,
3518         .writepages             = ext4_writepages,
3519         .write_begin            = ext4_write_begin,
3520         .write_end              = ext4_write_end,
3521         .bmap                   = ext4_bmap,
3522         .invalidatepage         = ext4_invalidatepage,
3523         .releasepage            = ext4_releasepage,
3524         .direct_IO              = ext4_direct_IO,
3525         .migratepage            = buffer_migrate_page,
3526         .is_partially_uptodate  = block_is_partially_uptodate,
3527         .error_remove_page      = generic_error_remove_page,
3528 };
3529 
3530 static const struct address_space_operations ext4_journalled_aops = {
3531         .readpage               = ext4_readpage,
3532         .readpages              = ext4_readpages,
3533         .writepage              = ext4_writepage,
3534         .writepages             = ext4_writepages,
3535         .write_begin            = ext4_write_begin,
3536         .write_end              = ext4_journalled_write_end,
3537         .set_page_dirty         = ext4_journalled_set_page_dirty,
3538         .bmap                   = ext4_bmap,
3539         .invalidatepage         = ext4_journalled_invalidatepage,
3540         .releasepage            = ext4_releasepage,
3541         .direct_IO              = ext4_direct_IO,
3542         .is_partially_uptodate  = block_is_partially_uptodate,
3543         .error_remove_page      = generic_error_remove_page,
3544 };
3545 
3546 static const struct address_space_operations ext4_da_aops = {
3547         .readpage               = ext4_readpage,
3548         .readpages              = ext4_readpages,
3549         .writepage              = ext4_writepage,
3550         .writepages             = ext4_writepages,
3551         .write_begin            = ext4_da_write_begin,
3552         .write_end              = ext4_da_write_end,
3553         .bmap                   = ext4_bmap,
3554         .invalidatepage         = ext4_da_invalidatepage,
3555         .releasepage            = ext4_releasepage,
3556         .direct_IO              = ext4_direct_IO,
3557         .migratepage            = buffer_migrate_page,
3558         .is_partially_uptodate  = block_is_partially_uptodate,
3559         .error_remove_page      = generic_error_remove_page,
3560 };
3561 
3562 void ext4_set_aops(struct inode *inode)
3563 {
3564         switch (ext4_inode_journal_mode(inode)) {
3565         case EXT4_INODE_ORDERED_DATA_MODE:
3566                 ext4_set_inode_state(inode, EXT4_STATE_ORDERED_MODE);
3567                 break;
3568         case EXT4_INODE_WRITEBACK_DATA_MODE:
3569                 ext4_clear_inode_state(inode, EXT4_STATE_ORDERED_MODE);
3570                 break;
3571         case EXT4_INODE_JOURNAL_DATA_MODE:
3572                 inode->i_mapping->a_ops = &ext4_journalled_aops;
3573                 return;
3574         default:
3575                 BUG();
3576         }
3577         if (test_opt(inode->i_sb, DELALLOC))
3578                 inode->i_mapping->a_ops = &ext4_da_aops;
3579         else
3580                 inode->i_mapping->a_ops = &ext4_aops;
3581 }
3582 
3583 static int __ext4_block_zero_page_range(handle_t *handle,
3584                 struct address_space *mapping, loff_t from, loff_t length)
3585 {
3586         ext4_fsblk_t index = from >> PAGE_SHIFT;
3587         unsigned offset = from & (PAGE_SIZE-1);
3588         unsigned blocksize, pos;
3589         ext4_lblk_t iblock;
3590         struct inode *inode = mapping->host;
3591         struct buffer_head *bh;
3592         struct page *page;
3593         int err = 0;
3594 
3595         page = find_or_create_page(mapping, from >> PAGE_SHIFT,
3596                                    mapping_gfp_constraint(mapping, ~__GFP_FS));
3597         if (!page)
3598                 return -ENOMEM;
3599 
3600         blocksize = inode->i_sb->s_blocksize;
3601 
3602         iblock = index << (PAGE_SHIFT - inode->i_sb->s_blocksize_bits);
3603 
3604         if (!page_has_buffers(page))
3605                 create_empty_buffers(page, blocksize, 0);
3606 
3607         /* Find the buffer that contains "offset" */
3608         bh = page_buffers(page);
3609         pos = blocksize;
3610         while (offset >= pos) {
3611                 bh = bh->b_this_page;
3612                 iblock++;
3613                 pos += blocksize;
3614         }
3615         if (buffer_freed(bh)) {
3616                 BUFFER_TRACE(bh, "freed: skip");
3617                 goto unlock;
3618         }
3619         if (!buffer_mapped(bh)) {
3620                 BUFFER_TRACE(bh, "unmapped");
3621                 ext4_get_block(inode, iblock, bh, 0);
3622                 /* unmapped? It's a hole - nothing to do */
3623                 if (!buffer_mapped(bh)) {
3624                         BUFFER_TRACE(bh, "still unmapped");
3625                         goto unlock;
3626                 }
3627         }
3628 
3629         /* Ok, it's mapped. Make sure it's up-to-date */
3630         if (PageUptodate(page))
3631                 set_buffer_uptodate(bh);
3632 
3633         if (!buffer_uptodate(bh)) {
3634                 err = -EIO;
3635                 ll_rw_block(READ, 1, &bh);
3636                 wait_on_buffer(bh);
3637                 /* Uhhuh. Read error. Complain and punt. */
3638                 if (!buffer_uptodate(bh))
3639                         goto unlock;
3640                 if (S_ISREG(inode->i_mode) &&
3641                     ext4_encrypted_inode(inode)) {
3642                         /* We expect the key to be set. */
3643                         BUG_ON(!ext4_has_encryption_key(inode));
3644                         BUG_ON(blocksize != PAGE_SIZE);
3645                         WARN_ON_ONCE(ext4_decrypt(page));
3646                 }
3647         }
3648         if (ext4_should_journal_data(inode)) {
3649                 BUFFER_TRACE(bh, "get write access");
3650                 err = ext4_journal_get_write_access(handle, bh);
3651                 if (err)
3652                         goto unlock;
3653         }
3654         zero_user(page, offset, length);
3655         BUFFER_TRACE(bh, "zeroed end of block");
3656 
3657         if (ext4_should_journal_data(inode)) {
3658                 err = ext4_handle_dirty_metadata(handle, inode, bh);
3659         } else {
3660                 err = 0;
3661                 mark_buffer_dirty(bh);
3662                 if (ext4_test_inode_state(inode, EXT4_STATE_ORDERED_MODE))
3663                         err = ext4_jbd2_file_inode(handle, inode);
3664         }
3665 
3666 unlock:
3667         unlock_page(page);
3668         put_page(page);
3669         return err;
3670 }
3671 
3672 /*
3673  * ext4_block_zero_page_range() zeros out a mapping of length 'length'
3674  * starting from file offset 'from'.  The range to be zero'd must
3675  * be contained with in one block.  If the specified range exceeds
3676  * the end of the block it will be shortened to end of the block
3677  * that cooresponds to 'from'
3678  */
3679 static int ext4_block_zero_page_range(handle_t *handle,
3680                 struct address_space *mapping, loff_t from, loff_t length)
3681 {
3682         struct inode *inode = mapping->host;
3683         unsigned offset = from & (PAGE_SIZE-1);
3684         unsigned blocksize = inode->i_sb->s_blocksize;
3685         unsigned max = blocksize - (offset & (blocksize - 1));
3686 
3687         /*
3688          * correct length if it does not fall between
3689          * 'from' and the end of the block
3690          */
3691         if (length > max || length < 0)
3692                 length = max;
3693 
3694         if (IS_DAX(inode))
3695                 return dax_zero_page_range(inode, from, length, ext4_get_block);
3696         return __ext4_block_zero_page_range(handle, mapping, from, length);
3697 }
3698 
3699 /*
3700  * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
3701  * up to the end of the block which corresponds to `from'.
3702  * This required during truncate. We need to physically zero the tail end
3703  * of that block so it doesn't yield old data if the file is later grown.
3704  */
3705 static int ext4_block_truncate_page(handle_t *handle,
3706                 struct address_space *mapping, loff_t from)
3707 {
3708         unsigned offset = from & (PAGE_SIZE-1);
3709         unsigned length;
3710         unsigned blocksize;
3711         struct inode *inode = mapping->host;
3712 
3713         blocksize = inode->i_sb->s_blocksize;
3714         length = blocksize - (offset & (blocksize - 1));
3715 
3716         return ext4_block_zero_page_range(handle, mapping, from, length);
3717 }
3718 
3719 int ext4_zero_partial_blocks(handle_t *handle, struct inode *inode,
3720                              loff_t lstart, loff_t length)
3721 {
3722         struct super_block *sb = inode->i_sb;
3723         struct address_space *mapping = inode->i_mapping;
3724         unsigned partial_start, partial_end;
3725         ext4_fsblk_t start, end;
3726         loff_t byte_end = (lstart + length - 1);
3727         int err = 0;
3728 
3729         partial_start = lstart & (sb->s_blocksize - 1);
3730         partial_end = byte_end & (sb->s_blocksize - 1);
3731 
3732         start = lstart >> sb->s_blocksize_bits;
3733         end = byte_end >> sb->s_blocksize_bits;
3734 
3735         /* Handle partial zero within the single block */
3736         if (start == end &&
3737             (partial_start || (partial_end != sb->s_blocksize - 1))) {
3738                 err = ext4_block_zero_page_range(handle, mapping,
3739                                                  lstart, length);
3740                 return err;
3741         }
3742         /* Handle partial zero out on the start of the range */
3743         if (partial_start) {
3744                 err = ext4_block_zero_page_range(handle, mapping,
3745                                                  lstart, sb->s_blocksize);
3746                 if (err)
3747                         return err;
3748         }
3749         /* Handle partial zero out on the end of the range */
3750         if (partial_end != sb->s_blocksize - 1)
3751                 err = ext4_block_zero_page_range(handle, mapping,
3752                                                  byte_end - partial_end,
3753                                                  partial_end + 1);
3754         return err;
3755 }
3756 
3757 int ext4_can_truncate(struct inode *inode)
3758 {
3759         if (S_ISREG(inode->i_mode))
3760                 return 1;
3761         if (S_ISDIR(inode->i_mode))
3762                 return 1;
3763         if (S_ISLNK(inode->i_mode))
3764                 return !ext4_inode_is_fast_symlink(inode);
3765         return 0;
3766 }
3767 
3768 /*
3769  * We have to make sure i_disksize gets properly updated before we truncate
3770  * page cache due to hole punching or zero range. Otherwise i_disksize update
3771  * can get lost as it may have been postponed to submission of writeback but
3772  * that will never happen after we truncate page cache.
3773  */
3774 int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset,
3775                                       loff_t len)
3776 {
3777         handle_t *handle;
3778         loff_t size = i_size_read(inode);
3779 
3780         WARN_ON(!inode_is_locked(inode));
3781         if (offset > size || offset + len < size)
3782                 return 0;
3783 
3784         if (EXT4_I(inode)->i_disksize >= size)
3785                 return 0;
3786 
3787         handle = ext4_journal_start(inode, EXT4_HT_MISC, 1);
3788         if (IS_ERR(handle))
3789                 return PTR_ERR(handle);
3790         ext4_update_i_disksize(inode, size);
3791         ext4_mark_inode_dirty(handle, inode);
3792         ext4_journal_stop(handle);
3793 
3794         return 0;
3795 }
3796 
3797 /*
3798  * ext4_punch_hole: punches a hole in a file by releaseing the blocks
3799  * associated with the given offset and length
3800  *
3801  * @inode:  File inode
3802  * @offset: The offset where the hole will begin
3803  * @len:    The length of the hole
3804  *
3805  * Returns: 0 on success or negative on failure
3806  */
3807 
3808 int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
3809 {
3810         struct super_block *sb = inode->i_sb;
3811         ext4_lblk_t first_block, stop_block;
3812         struct address_space *mapping = inode->i_mapping;
3813         loff_t first_block_offset, last_block_offset;
3814         handle_t *handle;
3815         unsigned int credits;
3816         int ret = 0;
3817 
3818         if (!S_ISREG(inode->i_mode))
3819                 return -EOPNOTSUPP;
3820 
3821         trace_ext4_punch_hole(inode, offset, length, 0);
3822 
3823         /*
3824          * Write out all dirty pages to avoid race conditions
3825          * Then release them.
3826          */
3827         if (mapping->nrpages && mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
3828                 ret = filemap_write_and_wait_range(mapping, offset,
3829                                                    offset + length - 1);
3830                 if (ret)
3831                         return ret;
3832         }
3833 
3834         inode_lock(inode);
3835 
3836         /* No need to punch hole beyond i_size */
3837         if (offset >= inode->i_size)
3838                 goto out_mutex;
3839 
3840         /*
3841          * If the hole extends beyond i_size, set the hole
3842          * to end after the page that contains i_size
3843          */
3844         if (offset + length > inode->i_size) {
3845                 length = inode->i_size +
3846                    PAGE_SIZE - (inode->i_size & (PAGE_SIZE - 1)) -
3847                    offset;
3848         }
3849 
3850         if (offset & (sb->s_blocksize - 1) ||
3851             (offset + length) & (sb->s_blocksize - 1)) {
3852                 /*
3853                  * Attach jinode to inode for jbd2 if we do any zeroing of
3854                  * partial block
3855                  */
3856                 ret = ext4_inode_attach_jinode(inode);
3857                 if (ret < 0)
3858                         goto out_mutex;
3859 
3860         }
3861 
3862         /* Wait all existing dio workers, newcomers will block on i_mutex */
3863         ext4_inode_block_unlocked_dio(inode);
3864         inode_dio_wait(inode);
3865 
3866         /*
3867          * Prevent page faults from reinstantiating pages we have released from
3868          * page cache.
3869          */
3870         down_write(&EXT4_I(inode)->i_mmap_sem);
3871         first_block_offset = round_up(offset, sb->s_blocksize);
3872         last_block_offset = round_down((offset + length), sb->s_blocksize) - 1;
3873 
3874         /* Now release the pages and zero block aligned part of pages*/
3875         if (last_block_offset > first_block_offset) {
3876                 ret = ext4_update_disksize_before_punch(inode, offset, length);
3877                 if (ret)
3878                         goto out_dio;
3879                 truncate_pagecache_range(inode, first_block_offset,
3880                                          last_block_offset);
3881         }
3882 
3883         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
3884                 credits = ext4_writepage_trans_blocks(inode);
3885         else
3886                 credits = ext4_blocks_for_truncate(inode);
3887         handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
3888         if (IS_ERR(handle)) {
3889                 ret = PTR_ERR(handle);
3890                 ext4_std_error(sb, ret);
3891                 goto out_dio;
3892         }
3893 
3894         ret = ext4_zero_partial_blocks(handle, inode, offset,
3895                                        length);
3896         if (ret)
3897                 goto out_stop;
3898 
3899         first_block = (offset + sb->s_blocksize - 1) >>
3900                 EXT4_BLOCK_SIZE_BITS(sb);
3901         stop_block = (offset + length) >> EXT4_BLOCK_SIZE_BITS(sb);
3902 
3903         /* If there are no blocks to remove, return now */
3904         if (first_block >= stop_block)
3905                 goto out_stop;
3906 
3907         down_write(&EXT4_I(inode)->i_data_sem);
3908         ext4_discard_preallocations(inode);
3909 
3910         ret = ext4_es_remove_extent(inode, first_block,
3911                                     stop_block - first_block);
3912         if (ret) {
3913                 up_write(&EXT4_I(inode)->i_data_sem);
3914                 goto out_stop;
3915         }
3916 
3917         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
3918                 ret = ext4_ext_remove_space(inode, first_block,
3919                                             stop_block - 1);
3920         else
3921                 ret = ext4_ind_remove_space(handle, inode, first_block,
3922                                             stop_block);
3923 
3924         up_write(&EXT4_I(inode)->i_data_sem);
3925         if (IS_SYNC(inode))
3926                 ext4_handle_sync(handle);
3927 
3928         inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
3929         ext4_mark_inode_dirty(handle, inode);
3930 out_stop:
3931         ext4_journal_stop(handle);
3932 out_dio:
3933         up_write(&EXT4_I(inode)->i_mmap_sem);
3934         ext4_inode_resume_unlocked_dio(inode);
3935 out_mutex:
3936         inode_unlock(inode);
3937         return ret;
3938 }
3939 
3940 int ext4_inode_attach_jinode(struct inode *inode)
3941 {
3942         struct ext4_inode_info *ei = EXT4_I(inode);
3943         struct jbd2_inode *jinode;
3944 
3945         if (ei->jinode || !EXT4_SB(inode->i_sb)->s_journal)
3946                 return 0;
3947 
3948         jinode = jbd2_alloc_inode(GFP_KERNEL);
3949         spin_lock(&inode->i_lock);
3950         if (!ei->jinode) {
3951                 if (!jinode) {
3952                         spin_unlock(&inode->i_lock);
3953                         return -ENOMEM;
3954                 }
3955                 ei->jinode = jinode;
3956                 jbd2_journal_init_jbd_inode(ei->jinode, inode);
3957                 jinode = NULL;
3958         }
3959         spin_unlock(&inode->i_lock);
3960         if (unlikely(jinode != NULL))
3961                 jbd2_free_inode(jinode);
3962         return 0;
3963 }
3964 
3965 /*
3966  * ext4_truncate()
3967  *
3968  * We block out ext4_get_block() block instantiations across the entire
3969  * transaction, and VFS/VM ensures that ext4_truncate() cannot run
3970  * simultaneously on behalf of the same inode.
3971  *
3972  * As we work through the truncate and commit bits of it to the journal there
3973  * is one core, guiding principle: the file's tree must always be consistent on
3974  * disk.  We must be able to restart the truncate after a crash.
3975  *
3976  * The file's tree may be transiently inconsistent in memory (although it
3977  * probably isn't), but whenever we close off and commit a journal transaction,
3978  * the contents of (the filesystem + the journal) must be consistent and
3979  * restartable.  It's pretty simple, really: bottom up, right to left (although
3980  * left-to-right works OK too).
3981  *
3982  * Note that at recovery time, journal replay occurs *before* the restart of
3983  * truncate against the orphan inode list.
3984  *
3985  * The committed inode has the new, desired i_size (which is the same as
3986  * i_disksize in this case).  After a crash, ext4_orphan_cleanup() will see
3987  * that this inode's truncate did not complete and it will again call
3988  * ext4_truncate() to have another go.  So there will be instantiated blocks
3989  * to the right of the truncation point in a crashed ext4 filesystem.  But
3990  * that's fine - as long as they are linked from the inode, the post-crash
3991  * ext4_truncate() run will find them and release them.
3992  */
3993 void ext4_truncate(struct inode *inode)
3994 {
3995         struct ext4_inode_info *ei = EXT4_I(inode);
3996         unsigned int credits;
3997         handle_t *handle;
3998         struct address_space *mapping = inode->i_mapping;
3999 
4000         /*
4001          * There is a possibility that we're either freeing the inode
4002          * or it's a completely new inode. In those cases we might not
4003          * have i_mutex locked because it's not necessary.
4004          */
4005         if (!(inode->i_state & (I_NEW|I_FREEING)))
4006                 WARN_ON(!inode_is_locked(inode));
4007         trace_ext4_truncate_enter(inode);
4008 
4009         if (!ext4_can_truncate(inode))
4010                 return;
4011 
4012         ext4_clear_inode_flag(inode, EXT4_INODE_EOFBLOCKS);
4013 
4014         if (inode->i_size == 0 && !test_opt(inode->i_sb, NO_AUTO_DA_ALLOC))
4015                 ext4_set_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
4016 
4017         if (ext4_has_inline_data(inode)) {
4018                 int has_inline = 1;
4019 
4020                 ext4_inline_data_truncate(inode, &has_inline);
4021                 if (has_inline)
4022                         return;
4023         }
4024 
4025         /* If we zero-out tail of the page, we have to create jinode for jbd2 */
4026         if (inode->i_size & (inode->i_sb->s_blocksize - 1)) {
4027                 if (ext4_inode_attach_jinode(inode) < 0)
4028                         return;
4029         }
4030 
4031         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
4032                 credits = ext4_writepage_trans_blocks(inode);
4033         else
4034                 credits = ext4_blocks_for_truncate(inode);
4035 
4036         handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
4037         if (IS_ERR(handle)) {
4038                 ext4_std_error(inode->i_sb, PTR_ERR(handle));
4039                 return;
4040         }
4041 
4042         if (inode->i_size & (inode->i_sb->s_blocksize - 1))
4043                 ext4_block_truncate_page(handle, mapping, inode->i_size);
4044 
4045         /*
4046          * We add the inode to the orphan list, so that if this
4047          * truncate spans multiple transactions, and we crash, we will
4048          * resume the truncate when the filesystem recovers.  It also
4049          * marks the inode dirty, to catch the new size.
4050          *
4051          * Implication: the file must always be in a sane, consistent
4052          * truncatable state while each transaction commits.
4053          */
4054         if (ext4_orphan_add(handle, inode))
4055                 goto out_stop;
4056 
4057         down_write(&EXT4_I(inode)->i_data_sem);
4058 
4059         ext4_discard_preallocations(inode);
4060 
4061         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
4062                 ext4_ext_truncate(handle, inode);
4063         else
4064                 ext4_ind_truncate(handle, inode);
4065 
4066         up_write(&ei->i_data_sem);
4067 
4068         if (IS_SYNC(inode))
4069                 ext4_handle_sync(handle);
4070 
4071 out_stop:
4072         /*
4073          * If this was a simple ftruncate() and the file will remain alive,
4074          * then we need to clear up the orphan record which we created above.
4075          * However, if this was a real unlink then we were called by
4076          * ext4_evict_inode(), and we allow that function to clean up the
4077          * orphan info for us.
4078          */
4079         if (inode->i_nlink)
4080                 ext4_orphan_del(handle, inode);
4081 
4082         inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
4083         ext4_mark_inode_dirty(handle, inode);
4084         ext4_journal_stop(handle);
4085 
4086         trace_ext4_truncate_exit(inode);
4087 }
4088 
4089 /*
4090  * ext4_get_inode_loc returns with an extra refcount against the inode's
4091  * underlying buffer_head on success. If 'in_mem' is true, we have all
4092  * data in memory that is needed to recreate the on-disk version of this
4093  * inode.
4094  */
4095 static int __ext4_get_inode_loc(struct inode *inode,
4096                                 struct ext4_iloc *iloc, int in_mem)
4097 {
4098         struct ext4_group_desc  *gdp;
4099         struct buffer_head      *bh;
4100         struct super_block      *sb = inode->i_sb;
4101         ext4_fsblk_t            block;
4102         int                     inodes_per_block, inode_offset;
4103 
4104         iloc->bh = NULL;
4105         if (!ext4_valid_inum(sb, inode->i_ino))
4106                 return -EFSCORRUPTED;
4107 
4108         iloc->block_group = (inode->i_ino - 1) / EXT4_INODES_PER_GROUP(sb);
4109         gdp = ext4_get_group_desc(sb, iloc->block_group, NULL);
4110         if (!gdp)
4111                 return -EIO;
4112 
4113         /*
4114          * Figure out the offset within the block group inode table
4115          */
4116         inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
4117         inode_offset = ((inode->i_ino - 1) %
4118                         EXT4_INODES_PER_GROUP(sb));
4119         block = ext4_inode_table(sb, gdp) + (inode_offset / inodes_per_block);
4120         iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb);
4121 
4122         bh = sb_getblk(sb, block);
4123         if (unlikely(!bh))
4124                 return -ENOMEM;
4125         if (!buffer_uptodate(bh)) {
4126                 lock_buffer(bh);
4127 
4128                 /*
4129                  * If the buffer has the write error flag, we have failed
4130                  * to write out another inode in the same block.  In this
4131                  * case, we don't have to read the block because we may
4132                  * read the old inode data successfully.
4133                  */
4134                 if (buffer_write_io_error(bh) && !buffer_uptodate(bh))
4135                         set_buffer_uptodate(bh);
4136 
4137                 if (buffer_uptodate(bh)) {
4138                         /* someone brought it uptodate while we waited */
4139                         unlock_buffer(bh);
4140                         goto has_buffer;
4141                 }
4142 
4143                 /*
4144                  * If we have all information of the inode in memory and this
4145                  * is the only valid inode in the block, we need not read the
4146                  * block.
4147                  */
4148                 if (in_mem) {
4149                         struct buffer_head *bitmap_bh;
4150                         int i, start;
4151 
4152                         start = inode_offset & ~(inodes_per_block - 1);
4153 
4154                         /* Is the inode bitmap in cache? */
4155                         bitmap_bh = sb_getblk(sb, ext4_inode_bitmap(sb, gdp));
4156                         if (unlikely(!bitmap_bh))
4157                                 goto make_io;
4158 
4159                         /*
4160                          * If the inode bitmap isn't in cache then the
4161                          * optimisation may end up performing two reads instead
4162                          * of one, so skip it.
4163                          */
4164                         if (!buffer_uptodate(bitmap_bh)) {
4165                                 brelse(bitmap_bh);
4166                                 goto make_io;
4167                         }
4168                         for (i = start; i < start + inodes_per_block; i++) {
4169                                 if (i == inode_offset)
4170                                         continue;
4171                                 if (ext4_test_bit(i, bitmap_bh->b_data))
4172                                         break;
4173                         }
4174                         brelse(bitmap_bh);
4175                         if (i == start + inodes_per_block) {
4176                                 /* all other inodes are free, so skip I/O */
4177                                 memset(bh->b_data, 0, bh->b_size);
4178                                 set_buffer_uptodate(bh);
4179                                 unlock_buffer(bh);
4180                                 goto has_buffer;
4181                         }
4182                 }
4183 
4184 make_io:
4185                 /*
4186                  * If we need to do any I/O, try to pre-readahead extra
4187                  * blocks from the inode table.
4188                  */
4189                 if (EXT4_SB(sb)->s_inode_readahead_blks) {
4190                         ext4_fsblk_t b, end, table;
4191                         unsigned num;
4192                         __u32 ra_blks = EXT4_SB(sb)->s_inode_readahead_blks;
4193 
4194                         table = ext4_inode_table(sb, gdp);
4195                         /* s_inode_readahead_blks is always a power of 2 */
4196                         b = block & ~((ext4_fsblk_t) ra_blks - 1);
4197                         if (table > b)
4198                                 b = table;
4199                         end = b + ra_blks;
4200                         num = EXT4_INODES_PER_GROUP(sb);
4201                         if (ext4_has_group_desc_csum(sb))
4202                                 num -= ext4_itable_unused_count(sb, gdp);
4203                         table += num / inodes_per_block;
4204                         if (end > table)
4205                                 end = table;
4206                         while (b <= end)
4207                                 sb_breadahead(sb, b++);
4208                 }
4209 
4210                 /*
4211                  * There are other valid inodes in the buffer, this inode
4212                  * has in-inode xattrs, or we don't have this inode in memory.
4213                  * Read the block from disk.
4214                  */
4215                 trace_ext4_load_inode(inode);
4216                 get_bh(bh);
4217                 bh->b_end_io = end_buffer_read_sync;
4218                 submit_bh(READ | REQ_META | REQ_PRIO, bh);
4219                 wait_on_buffer(bh);
4220                 if (!buffer_uptodate(bh)) {
4221                         EXT4_ERROR_INODE_BLOCK(inode, block,
4222                                                "unable to read itable block");
4223                         brelse(bh);
4224                         return -EIO;
4225                 }
4226         }
4227 has_buffer:
4228         iloc->bh = bh;
4229         return 0;
4230 }
4231 
4232 int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
4233 {
4234         /* We have all inode data except xattrs in memory here. */
4235         return __ext4_get_inode_loc(inode, iloc,
4236                 !ext4_test_inode_state(inode, EXT4_STATE_XATTR));
4237 }
4238 
4239 void ext4_set_inode_flags(struct inode *inode)
4240 {
4241         unsigned int flags = EXT4_I(inode)->i_flags;
4242         unsigned int new_fl = 0;
4243 
4244         if (flags & EXT4_SYNC_FL)
4245                 new_fl |= S_SYNC;
4246         if (flags & EXT4_APPEND_FL)
4247                 new_fl |= S_APPEND;
4248         if (flags & EXT4_IMMUTABLE_FL)
4249                 new_fl |= S_IMMUTABLE;
4250         if (flags & EXT4_NOATIME_FL)
4251                 new_fl |= S_NOATIME;
4252         if (flags & EXT4_DIRSYNC_FL)
4253                 new_fl |= S_DIRSYNC;
4254         if (test_opt(inode->i_sb, DAX) && S_ISREG(inode->i_mode))
4255                 new_fl |= S_DAX;
4256         inode_set_flags(inode, new_fl,
4257                         S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|S_DAX);
4258 }
4259 
4260 /* Propagate flags from i_flags to EXT4_I(inode)->i_flags */
4261 void ext4_get_inode_flags(struct ext4_inode_info *ei)
4262 {
4263         unsigned int vfs_fl;
4264         unsigned long old_fl, new_fl;
4265 
4266         do {
4267                 vfs_fl = ei->vfs_inode.i_flags;
4268                 old_fl = ei->i_flags;
4269                 new_fl = old_fl & ~(EXT4_SYNC_FL|EXT4_APPEND_FL|
4270                                 EXT4_IMMUTABLE_FL|EXT4_NOATIME_FL|
4271                                 EXT4_DIRSYNC_FL);
4272                 if (vfs_fl & S_SYNC)
4273                         new_fl |= EXT4_SYNC_FL;
4274                 if (vfs_fl & S_APPEND)
4275                         new_fl |= EXT4_APPEND_FL;
4276                 if (vfs_fl & S_IMMUTABLE)
4277                         new_fl |= EXT4_IMMUTABLE_FL;
4278                 if (vfs_fl & S_NOATIME)
4279                         new_fl |= EXT4_NOATIME_FL;
4280                 if (vfs_fl & S_DIRSYNC)
4281                         new_fl |= EXT4_DIRSYNC_FL;
4282         } while (cmpxchg(&ei->i_flags, old_fl, new_fl) != old_fl);
4283 }
4284 
4285 static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode,
4286                                   struct ext4_inode_info *ei)
4287 {
4288         blkcnt_t i_blocks ;
4289         struct inode *inode = &(ei->vfs_inode);
4290         struct super_block *sb = inode->i_sb;
4291 
4292         if (ext4_has_feature_huge_file(sb)) {
4293                 /* we are using combined 48 bit field */
4294                 i_blocks = ((u64)le16_to_cpu(raw_inode->i_blocks_high)) << 32 |
4295                                         le32_to_cpu(raw_inode->i_blocks_lo);
4296                 if (ext4_test_inode_flag(inode, EXT4_INODE_HUGE_FILE)) {
4297                         /* i_blocks represent file system block size */
4298                         return i_blocks  << (inode->i_blkbits - 9);
4299                 } else {
4300                         return i_blocks;
4301                 }
4302         } else {
4303                 return le32_to_cpu(raw_inode->i_blocks_lo);
4304         }
4305 }
4306 
4307 static inline void ext4_iget_extra_inode(struct inode *inode,
4308                                          struct ext4_inode *raw_inode,
4309                                          struct ext4_inode_info *ei)
4310 {
4311         __le32 *magic = (void *)raw_inode +
4312                         EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize;
4313         if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC)) {
4314                 ext4_set_inode_state(inode, EXT4_STATE_XATTR);
4315                 ext4_find_inline_data_nolock(inode);
4316         } else
4317                 EXT4_I(inode)->i_inline_off = 0;
4318 }
4319 
4320 int ext4_get_projid(struct inode *inode, kprojid_t *projid)
4321 {
4322         if (!EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb, EXT4_FEATURE_RO_COMPAT_PROJECT))
4323                 return -EOPNOTSUPP;
4324         *projid = EXT4_I(inode)->i_projid;
4325         return 0;
4326 }
4327 
4328 struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
4329 {
4330         struct ext4_iloc iloc;
4331         struct ext4_inode *raw_inode;
4332         struct ext4_inode_info *ei;
4333         struct inode *inode;
4334         journal_t *journal = EXT4_SB(sb)->s_journal;
4335         long ret;
4336         int block;
4337         uid_t i_uid;
4338         gid_t i_gid;
4339         projid_t i_projid;
4340 
4341         inode = iget_locked(sb, ino);
4342         if (!inode)
4343                 return ERR_PTR(-ENOMEM);
4344         if (!(inode->i_state & I_NEW))
4345                 return inode;
4346 
4347         ei = EXT4_I(inode);
4348         iloc.bh = NULL;
4349 
4350         ret = __ext4_get_inode_loc(inode, &iloc, 0);
4351         if (ret < 0)
4352                 goto bad_inode;
4353         raw_inode = ext4_raw_inode(&iloc);
4354 
4355         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
4356                 ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
4357                 if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
4358                     EXT4_INODE_SIZE(inode->i_sb)) {
4359                         EXT4_ERROR_INODE(inode, "bad extra_isize (%u != %u)",
4360                                 EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize,
4361                                 EXT4_INODE_SIZE(inode->i_sb));
4362                         ret = -EFSCORRUPTED;
4363                         goto bad_inode;
4364                 }
4365         } else
4366                 ei->i_extra_isize = 0;
4367 
4368         /* Precompute checksum seed for inode metadata */
4369         if (ext4_has_metadata_csum(sb)) {
4370                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
4371                 __u32 csum;
4372                 __le32 inum = cpu_to_le32(inode->i_ino);
4373                 __le32 gen = raw_inode->i_generation;
4374                 csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&inum,
4375                                    sizeof(inum));
4376                 ei->i_csum_seed = ext4_chksum(sbi, csum, (__u8 *)&gen,
4377                                               sizeof(gen));
4378         }
4379 
4380         if (!ext4_inode_csum_verify(inode, raw_inode, ei)) {
4381                 EXT4_ERROR_INODE(inode, "checksum invalid");
4382                 ret = -EFSBADCRC;
4383                 goto bad_inode;
4384         }
4385 
4386         inode->i_mode = le16_to_cpu(raw_inode->i_mode);
4387         i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
4388         i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
4389         if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_PROJECT) &&
4390             EXT4_INODE_SIZE(sb) > EXT4_GOOD_OLD_INODE_SIZE &&
4391             EXT4_FITS_IN_INODE(raw_inode, ei, i_projid))
4392                 i_projid = (projid_t)le32_to_cpu(raw_inode->i_projid);
4393         else
4394                 i_projid = EXT4_DEF_PROJID;
4395 
4396         if (!(test_opt(inode->i_sb, NO_UID32))) {
4397                 i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
4398                 i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
4399         }
4400         i_uid_write(inode, i_uid);
4401         i_gid_write(inode, i_gid);
4402         ei->i_projid = make_kprojid(&init_user_ns, i_projid);
4403         set_nlink(inode, le16_to_cpu(raw_inode->i_links_count));
4404 
4405         ext4_clear_state_flags(ei);     /* Only relevant on 32-bit archs */
4406         ei->i_inline_off = 0;
4407         ei->i_dir_start_lookup = 0;
4408         ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
4409         /* We now have enough fields to check if the inode was active or not.
4410          * This is needed because nfsd might try to access dead inodes
4411          * the test is that same one that e2fsck uses
4412          * NeilBrown 1999oct15
4413          */
4414         if (inode->i_nlink == 0) {
4415                 if ((inode->i_mode == 0 ||
4416                      !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) &&
4417                     ino != EXT4_BOOT_LOADER_INO) {
4418                         /* this inode is deleted */
4419                         ret = -ESTALE;
4420                         goto bad_inode;
4421                 }
4422                 /* The only unlinked inodes we let through here have
4423                  * valid i_mode and are being read by the orphan
4424                  * recovery code: that's fine, we're about to complete
4425                  * the process of deleting those.
4426                  * OR it is the EXT4_BOOT_LOADER_INO which is
4427                  * not initialized on a new filesystem. */
4428         }
4429         ei->i_flags = le32_to_cpu(raw_inode->i_flags);
4430         inode->i_blocks = ext4_inode_blocks(raw_inode, ei);
4431         ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo);
4432         if (ext4_has_feature_64bit(sb))
4433                 ei->i_file_acl |=
4434                         ((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32;
4435         inode->i_size = ext4_isize(raw_inode);
4436         ei->i_disksize = inode->i_size;
4437 #ifdef CONFIG_QUOTA
4438         ei->i_reserved_quota = 0;
4439 #endif
4440         inode->i_generation = le32_to_cpu(raw_inode->i_generation);
4441         ei->i_block_group = iloc.block_group;
4442         ei->i_last_alloc_group = ~0;
4443         /*
4444          * NOTE! The in-memory inode i_data array is in little-endian order
4445          * even on big-endian machines: we do NOT byteswap the block numbers!
4446          */
4447         for (block = 0; block < EXT4_N_BLOCKS; block++)
4448                 ei->i_data[block] = raw_inode->i_block[block];
4449         INIT_LIST_HEAD(&ei->i_orphan);
4450 
4451         /*
4452          * Set transaction id's of transactions that have to be committed
4453          * to finish f[data]sync. We set them to currently running transaction
4454          * as we cannot be sure that the inode or some of its metadata isn't
4455          * part of the transaction - the inode could have been reclaimed and
4456          * now it is reread from disk.
4457          */
4458         if (journal) {
4459                 transaction_t *transaction;
4460                 tid_t tid;
4461 
4462                 read_lock(&journal->j_state_lock);
4463                 if (journal->j_running_transaction)
4464                         transaction = journal->j_running_transaction;
4465                 else
4466                         transaction = journal->j_committing_transaction;
4467                 if (transaction)
4468                         tid = transaction->t_tid;
4469                 else
4470                         tid = journal->j_commit_sequence;
4471                 read_unlock(&journal->j_state_lock);
4472                 ei->i_sync_tid = tid;
4473                 ei->i_datasync_tid = tid;
4474         }
4475 
4476         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
4477                 if (ei->i_extra_isize == 0) {
4478                         /* The extra space is currently unused. Use it. */
4479                         ei->i_extra_isize = sizeof(struct ext4_inode) -
4480                                             EXT4_GOOD_OLD_INODE_SIZE;
4481                 } else {
4482                         ext4_iget_extra_inode(inode, raw_inode, ei);
4483                 }
4484         }
4485 
4486         EXT4_INODE_GET_XTIME(i_ctime, inode, raw_inode);
4487         EXT4_INODE_GET_XTIME(i_mtime, inode, raw_inode);
4488         EXT4_INODE_GET_XTIME(i_atime, inode, raw_inode);
4489         EXT4_EINODE_GET_XTIME(i_crtime, ei, raw_inode);
4490 
4491         if (likely(!test_opt2(inode->i_sb, HURD_COMPAT))) {
4492                 inode->i_version = le32_to_cpu(raw_inode->i_disk_version);
4493                 if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
4494                         if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
4495                                 inode->i_version |=
4496                     (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
4497                 }
4498         }
4499 
4500         ret = 0;
4501         if (ei->i_file_acl &&
4502             !ext4_data_block_valid(EXT4_SB(sb), ei->i_file_acl, 1)) {
4503                 EXT4_ERROR_INODE(inode, "bad extended attribute block %llu",
4504                                  ei->i_file_acl);
4505                 ret = -EFSCORRUPTED;
4506                 goto bad_inode;
4507         } else if (!ext4_has_inline_data(inode)) {
4508                 if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
4509                         if ((S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
4510                             (S_ISLNK(inode->i_mode) &&
4511                              !ext4_inode_is_fast_symlink(inode))))
4512                                 /* Validate extent which is part of inode */
4513                                 ret = ext4_ext_check_inode(inode);
4514                 } else if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
4515                            (S_ISLNK(inode->i_mode) &&
4516                             !ext4_inode_is_fast_symlink(inode))) {
4517                         /* Validate block references which are part of inode */
4518                         ret = ext4_ind_check_inode(inode);
4519                 }
4520         }
4521         if (ret)
4522                 goto bad_inode;
4523 
4524         if (S_ISREG(inode->i_mode)) {
4525                 inode->i_op = &ext4_file_inode_operations;
4526                 inode->i_fop = &ext4_file_operations;
4527                 ext4_set_aops(inode);
4528         } else if (S_ISDIR(inode->i_mode)) {
4529                 inode->i_op = &ext4_dir_inode_operations;
4530                 inode->i_fop = &ext4_dir_operations;
4531         } else if (S_ISLNK(inode->i_mode)) {
4532                 if (ext4_encrypted_inode(inode)) {
4533                         inode->i_op = &ext4_encrypted_symlink_inode_operations;
4534                         ext4_set_aops(inode);
4535                 } else if (ext4_inode_is_fast_symlink(inode)) {
4536                         inode->i_link = (char *)ei->i_data;
4537                         inode->i_op = &ext4_fast_symlink_inode_operations;
4538                         nd_terminate_link(ei->i_data, inode->i_size,
4539                                 sizeof(ei->i_data) - 1);
4540                 } else {
4541                         inode->i_op = &ext4_symlink_inode_operations;
4542                         ext4_set_aops(inode);
4543                 }
4544                 inode_nohighmem(inode);
4545         } else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
4546               S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
4547                 inode->i_op = &ext4_special_inode_operations;
4548                 if (raw_inode->i_block[0])
4549                         init_special_inode(inode, inode->i_mode,
4550                            old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
4551                 else
4552                         init_special_inode(inode, inode->i_mode,
4553                            new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
4554         } else if (ino == EXT4_BOOT_LOADER_INO) {
4555                 make_bad_inode(inode);
4556         } else {
4557                 ret = -EFSCORRUPTED;
4558                 EXT4_ERROR_INODE(inode, "bogus i_mode (%o)", inode->i_mode);
4559                 goto bad_inode;
4560         }
4561         brelse(iloc.bh);
4562         ext4_set_inode_flags(inode);
4563         unlock_new_inode(inode);
4564         return inode;
4565 
4566 bad_inode:
4567         brelse(iloc.bh);
4568         iget_failed(inode);
4569         return ERR_PTR(ret);
4570 }
4571 
4572 struct inode *ext4_iget_normal(struct super_block *sb, unsigned long ino)
4573 {
4574         if (ino < EXT4_FIRST_INO(sb) && ino != EXT4_ROOT_INO)
4575                 return ERR_PTR(-EFSCORRUPTED);
4576         return ext4_iget(sb, ino);
4577 }
4578 
4579 static int ext4_inode_blocks_set(handle_t *handle,
4580                                 struct ext4_inode *raw_inode,
4581                                 struct ext4_inode_info *ei)
4582 {
4583         struct inode *inode = &(ei->vfs_inode);
4584         u64 i_blocks = inode->i_blocks;
4585         struct super_block *sb = inode->i_sb;
4586 
4587         if (i_blocks <= ~0U) {
4588                 /*
4589                  * i_blocks can be represented in a 32 bit variable
4590                  * as multiple of 512 bytes
4591                  */
4592                 raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
4593                 raw_inode->i_blocks_high = 0;
4594                 ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
4595                 return 0;
4596         }
4597         if (!ext4_has_feature_huge_file(sb))
4598                 return -EFBIG;
4599 
4600         if (i_blocks <= 0xffffffffffffULL) {
4601                 /*
4602                  * i_blocks can be represented in a 48 bit variable
4603                  * as multiple of 512 bytes
4604                  */
4605                 raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
4606                 raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
4607                 ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
4608         } else {
4609                 ext4_set_inode_flag(inode, EXT4_INODE_HUGE_FILE);
4610                 /* i_block is stored in file system block size */
4611                 i_blocks = i_blocks >> (inode->i_blkbits - 9);
4612                 raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
4613                 raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
4614         }
4615         return 0;
4616 }
4617 
4618 struct other_inode {
4619         unsigned long           orig_ino;
4620         struct ext4_inode       *raw_inode;
4621 };
4622 
4623 static int other_inode_match(struct inode * inode, unsigned long ino,
4624                              void *data)
4625 {
4626         struct other_inode *oi = (struct other_inode *) data;
4627 
4628         if ((inode->i_ino != ino) ||
4629             (inode->i_state & (I_FREEING | I_WILL_FREE | I_NEW |
4630                                I_DIRTY_SYNC | I_DIRTY_DATASYNC)) ||
4631             ((inode->i_state & I_DIRTY_TIME) == 0))
4632                 return 0;
4633         spin_lock(&inode->i_lock);
4634         if (((inode->i_state & (I_FREEING | I_WILL_FREE | I_NEW |
4635                                 I_DIRTY_SYNC | I_DIRTY_DATASYNC)) == 0) &&
4636             (inode->i_state & I_DIRTY_TIME)) {
4637                 struct ext4_inode_info  *ei = EXT4_I(inode);
4638 
4639                 inode->i_state &= ~(I_DIRTY_TIME | I_DIRTY_TIME_EXPIRED);
4640                 spin_unlock(&inode->i_lock);
4641 
4642                 spin_lock(&ei->i_raw_lock);
4643                 EXT4_INODE_SET_XTIME(i_ctime, inode, oi->raw_inode);
4644                 EXT4_INODE_SET_XTIME(i_mtime, inode, oi->raw_inode);
4645                 EXT4_INODE_SET_XTIME(i_atime, inode, oi->raw_inode);
4646                 ext4_inode_csum_set(inode, oi->raw_inode, ei);
4647                 spin_unlock(&ei->i_raw_lock);
4648                 trace_ext4_other_inode_update_time(inode, oi->orig_ino);
4649                 return -1;
4650         }
4651         spin_unlock(&inode->i_lock);
4652         return -1;
4653 }
4654 
4655 /*
4656  * Opportunistically update the other time fields for other inodes in
4657  * the same inode table block.
4658  */
4659 static void ext4_update_other_inodes_time(struct super_block *sb,
4660                                           unsigned long orig_ino, char *buf)
4661 {
4662         struct other_inode oi;
4663         unsigned long ino;
4664         int i, inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
4665         int inode_size = EXT4_INODE_SIZE(sb);
4666 
4667         oi.orig_ino = orig_ino;
4668         /*
4669          * Calculate the first inode in the inode table block.  Inode
4670          * numbers are one-based.  That is, the first inode in a block
4671          * (assuming 4k blocks and 256 byte inodes) is (n*16 + 1).
4672          */
4673         ino = ((orig_ino - 1) & ~(inodes_per_block - 1)) + 1;
4674         for (i = 0; i < inodes_per_block; i++, ino++, buf += inode_size) {
4675                 if (ino == orig_ino)
4676                         continue;
4677                 oi.raw_inode = (struct ext4_inode *) buf;
4678                 (void) find_inode_nowait(sb, ino, other_inode_match, &oi);
4679         }
4680 }
4681 
4682 /*
4683  * Post the struct inode info into an on-disk inode location in the
4684  * buffer-cache.  This gobbles the caller's reference to the
4685  * buffer_head in the inode location struct.
4686  *
4687  * The caller must have write access to iloc->bh.
4688  */
4689 static int ext4_do_update_inode(handle_t *handle,
4690                                 struct inode *inode,
4691                                 struct ext4_iloc *iloc)
4692 {
4693         struct ext4_inode *raw_inode = ext4_raw_inode(iloc);
4694         struct ext4_inode_info *ei = EXT4_I(inode);
4695         struct buffer_head *bh = iloc->bh;
4696         struct super_block *sb = inode->i_sb;
4697         int err = 0, rc, block;
4698         int need_datasync = 0, set_large_file = 0;
4699         uid_t i_uid;
4700         gid_t i_gid;
4701         projid_t i_projid;
4702 
4703         spin_lock(&ei->i_raw_lock);
4704 
4705         /* For fields not tracked in the in-memory inode,
4706          * initialise them to zero for new inodes. */
4707         if (ext4_test_inode_state(inode, EXT4_STATE_NEW))
4708                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
4709 
4710         ext4_get_inode_flags(ei);
4711         raw_inode->i_mode = cpu_to_le16(inode->i_mode);
4712         i_uid = i_uid_read(inode);
4713         i_gid = i_gid_read(inode);
4714         i_projid = from_kprojid(&init_user_ns, ei->i_projid);
4715         if (!(test_opt(inode->i_sb, NO_UID32))) {
4716                 raw_inode->i_uid_low = cpu_to_le16(low_16_bits(i_uid));
4717                 raw_inode->i_gid_low = cpu_to_le16(low_16_bits(i_gid));
4718 /*
4719  * Fix up interoperability with old kernels. Otherwise, old inodes get
4720  * re-used with the upper 16 bits of the uid/gid intact
4721  */
4722                 if (!ei->i_dtime) {
4723                         raw_inode->i_uid_high =
4724                                 cpu_to_le16(high_16_bits(i_uid));
4725                         raw_inode->i_gid_high =
4726                                 cpu_to_le16(high_16_bits(i_gid));
4727                 } else {
4728                         raw_inode->i_uid_high = 0;
4729                         raw_inode->i_gid_high = 0;
4730                 }
4731         } else {
4732                 raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(i_uid));
4733                 raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(i_gid));
4734                 raw_inode->i_uid_high = 0;
4735                 raw_inode->i_gid_high = 0;
4736         }
4737         raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
4738 
4739         EXT4_INODE_SET_XTIME(i_ctime, inode, raw_inode);
4740         EXT4_INODE_SET_XTIME(i_mtime, inode, raw_inode);
4741         EXT4_INODE_SET_XTIME(i_atime, inode, raw_inode);
4742         EXT4_EINODE_SET_XTIME(i_crtime, ei, raw_inode);
4743 
4744         err = ext4_inode_blocks_set(handle, raw_inode, ei);
4745         if (err) {
4746                 spin_unlock(&ei->i_raw_lock);
4747                 goto out_brelse;
4748         }
4749         raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
4750         raw_inode->i_flags = cpu_to_le32(ei->i_flags & 0xFFFFFFFF);
4751         if (likely(!test_opt2(inode->i_sb, HURD_COMPAT)))
4752                 raw_inode->i_file_acl_high =
4753                         cpu_to_le16(ei->i_file_acl >> 32);
4754         raw_inode->i_file_acl_lo = cpu_to_le32(ei->i_file_acl);
4755         if (ei->i_disksize != ext4_isize(raw_inode)) {
4756                 ext4_isize_set(raw_inode, ei->i_disksize);
4757                 need_datasync = 1;
4758         }
4759         if (ei->i_disksize > 0x7fffffffULL) {
4760                 if (!ext4_has_feature_large_file(sb) ||
4761                                 EXT4_SB(sb)->s_es->s_rev_level ==
4762                     cpu_to_le32(EXT4_GOOD_OLD_REV))
4763                         set_large_file = 1;
4764         }
4765         raw_inode->i_generation = cpu_to_le32(inode->i_generation);
4766         if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
4767                 if (old_valid_dev(inode->i_rdev)) {
4768                         raw_inode->i_block[0] =
4769                                 cpu_to_le32(old_encode_dev(inode->i_rdev));
4770                         raw_inode->i_block[1] = 0;
4771                 } else {
4772                         raw_inode->i_block[0] = 0;
4773                         raw_inode->i_block[1] =
4774                                 cpu_to_le32(new_encode_dev(inode->i_rdev));
4775                         raw_inode->i_block[2] = 0;
4776                 }
4777         } else if (!ext4_has_inline_data(inode)) {
4778                 for (block = 0; block < EXT4_N_BLOCKS; block++)
4779                         raw_inode->i_block[block] = ei->i_data[block];
4780         }
4781 
4782         if (likely(!test_opt2(inode->i_sb, HURD_COMPAT))) {
4783                 raw_inode->i_disk_version = cpu_to_le32(inode->i_version);
4784                 if (ei->i_extra_isize) {
4785                         if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
4786                                 raw_inode->i_version_hi =
4787                                         cpu_to_le32(inode->i_version >> 32);
4788                         raw_inode->i_extra_isize =
4789                                 cpu_to_le16(ei->i_extra_isize);
4790                 }
4791         }
4792 
4793         BUG_ON(!EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,
4794                         EXT4_FEATURE_RO_COMPAT_PROJECT) &&
4795                i_projid != EXT4_DEF_PROJID);
4796 
4797         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
4798             EXT4_FITS_IN_INODE(raw_inode, ei, i_projid))
4799                 raw_inode->i_projid = cpu_to_le32(i_projid);
4800 
4801         ext4_inode_csum_set(inode, raw_inode, ei);
4802         spin_unlock(&ei->i_raw_lock);
4803         if (inode->i_sb->s_flags & MS_LAZYTIME)
4804                 ext4_update_other_inodes_time(inode->i_sb, inode->i_ino,
4805                                               bh->b_data);
4806 
4807         BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
4808         rc = ext4_handle_dirty_metadata(handle, NULL, bh);
4809         if (!err)
4810                 err = rc;
4811         ext4_clear_inode_state(inode, EXT4_STATE_NEW);
4812         if (set_large_file) {
4813                 BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get write access");
4814                 err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
4815                 if (err)
4816                         goto out_brelse;
4817                 ext4_update_dynamic_rev(sb);
4818                 ext4_set_feature_large_file(sb);
4819                 ext4_handle_sync(handle);
4820                 err = ext4_handle_dirty_super(handle, sb);
4821         }
4822         ext4_update_inode_fsync_trans(handle, inode, need_datasync);
4823 out_brelse:
4824         brelse(bh);
4825         ext4_std_error(inode->i_sb, err);
4826         return err;
4827 }
4828 
4829 /*
4830  * ext4_write_inode()
4831  *
4832  * We are called from a few places:
4833  *
4834  * - Within generic_file_aio_write() -> generic_write_sync() for O_SYNC files.
4835  *   Here, there will be no transaction running. We wait for any running
4836  *   transaction to commit.
4837  *
4838  * - Within flush work (sys_sync(), kupdate and such).
4839  *   We wait on commit, if told to.
4840  *
4841  * - Within iput_final() -> write_inode_now()
4842  *   We wait on commit, if told to.
4843  *
4844  * In all cases it is actually safe for us to return without doing anything,
4845  * because the inode has been copied into a raw inode buffer in
4846  * ext4_mark_inode_dirty().  This is a correctness thing for WB_SYNC_ALL
4847  * writeback.
4848  *
4849  * Note that we are absolutely dependent upon all inode dirtiers doing the
4850  * right thing: they *must* call mark_inode_dirty() after dirtying info in
4851  * which we are interested.
4852  *
4853  * It would be a bug for them to not do this.  The code:
4854  *
4855  *      mark_inode_dirty(inode)
4856  *      stuff();
4857  *      inode->i_size = expr;
4858  *
4859  * is in error because write_inode() could occur while `stuff()' is running,
4860  * and the new i_size will be lost.  Plus the inode will no longer be on the
4861  * superblock's dirty inode list.
4862  */
4863 int ext4_write_inode(struct inode *inode, struct writeback_control *wbc)
4864 {
4865         int err;
4866 
4867         if (WARN_ON_ONCE(current->flags & PF_MEMALLOC))
4868                 return 0;
4869 
4870         if (EXT4_SB(inode->i_sb)->s_journal) {
4871                 if (ext4_journal_current_handle()) {
4872                         jbd_debug(1, "called recursively, non-PF_MEMALLOC!\n");
4873                         dump_stack();
4874                         return -EIO;
4875                 }
4876 
4877                 /*
4878                  * No need to force transaction in WB_SYNC_NONE mode. Also
4879                  * ext4_sync_fs() will force the commit after everything is
4880                  * written.
4881                  */
4882                 if (wbc->sync_mode != WB_SYNC_ALL || wbc->for_sync)
4883                         return 0;
4884 
4885                 err = ext4_force_commit(inode->i_sb);
4886         } else {
4887                 struct ext4_iloc iloc;
4888 
4889                 err = __ext4_get_inode_loc(inode, &iloc, 0);
4890                 if (err)
4891                         return err;
4892                 /*
4893                  * sync(2) will flush the whole buffer cache. No need to do
4894                  * it here separately for each inode.
4895                  */
4896                 if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync)
4897                         sync_dirty_buffer(iloc.bh);
4898                 if (buffer_req(iloc.bh) && !buffer_uptodate(iloc.bh)) {
4899                         EXT4_ERROR_INODE_BLOCK(inode, iloc.bh->b_blocknr,
4900                                          "IO error syncing inode");
4901                         err = -EIO;
4902                 }
4903                 brelse(iloc.bh);
4904         }
4905         return err;
4906 }
4907 
4908 /*
4909  * In data=journal mode ext4_journalled_invalidatepage() may fail to invalidate
4910  * buffers that are attached to a page stradding i_size and are undergoing
4911  * commit. In that case we have to wait for commit to finish and try again.
4912  */
4913 static void ext4_wait_for_tail_page_commit(struct inode *inode)
4914 {
4915         struct page *page;
4916         unsigned offset;
4917         journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
4918         tid_t commit_tid = 0;
4919         int ret;
4920 
4921         offset = inode->i_size & (PAGE_SIZE - 1);
4922         /*
4923          * All buffers in the last page remain valid? Then there's nothing to
4924          * do. We do the check mainly to optimize the common PAGE_SIZE ==
4925          * blocksize case
4926          */
4927         if (offset > PAGE_SIZE - (1 << inode->i_blkbits))
4928                 return;
4929         while (1) {
4930                 page = find_lock_page(inode->i_mapping,
4931                                       inode->i_size >> PAGE_SHIFT);
4932                 if (!page)
4933                         return;
4934                 ret = __ext4_journalled_invalidatepage(page, offset,
4935                                                 PAGE_SIZE - offset);
4936                 unlock_page(page);
4937                 put_page(page);
4938                 if (ret != -EBUSY)
4939                         return;
4940                 commit_tid = 0;
4941                 read_lock(&journal->j_state_lock);
4942                 if (journal->j_committing_transaction)
4943                         commit_tid = journal->j_committing_transaction->t_tid;
4944                 read_unlock(&journal->j_state_lock);
4945                 if (commit_tid)
4946                         jbd2_log_wait_commit(journal, commit_tid);
4947         }
4948 }
4949 
4950 /*
4951  * ext4_setattr()
4952  *
4953  * Called from notify_change.
4954  *
4955  * We want to trap VFS attempts to truncate the file as soon as
4956  * possible.  In particular, we want to make sure that when the VFS
4957  * shrinks i_size, we put the inode on the orphan list and modify
4958  * i_disksize immediately, so that during the subsequent flushing of
4959  * dirty pages and freeing of disk blocks, we can guarantee that any
4960  * commit will leave the blocks being flushed in an unused state on
4961  * disk.  (On recovery, the inode will get truncated and the blocks will
4962  * be freed, so we have a strong guarantee that no future commit will
4963  * leave these blocks visible to the user.)
4964  *
4965  * Another thing we have to assure is that if we are in ordered mode
4966  * and inode is still attached to the committing transaction, we must
4967  * we start writeout of all the dirty pages which are being truncated.
4968  * This way we are sure that all the data written in the previous
4969  * transaction are already on disk (truncate waits for pages under
4970  * writeback).
4971  *
4972  * Called with inode->i_mutex down.
4973  */
4974 int ext4_setattr(struct dentry *dentry, struct iattr *attr)
4975 {
4976         struct inode *inode = d_inode(dentry);
4977         int error, rc = 0;
4978         int orphan = 0;
4979         const unsigned int ia_valid = attr->ia_valid;
4980 
4981         error = inode_change_ok(inode, attr);
4982         if (error)
4983                 return error;
4984 
4985         if (is_quota_modification(inode, attr)) {
4986                 error = dquot_initialize(inode);
4987                 if (error)
4988                         return error;
4989         }
4990         if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, inode->i_uid)) ||
4991             (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, inode->i_gid))) {
4992                 handle_t *handle;
4993 
4994                 /* (user+group)*(old+new) structure, inode write (sb,
4995                  * inode block, ? - but truncate inode update has it) */
4996                 handle = ext4_journal_start(inode, EXT4_HT_QUOTA,
4997                         (EXT4_MAXQUOTAS_INIT_BLOCKS(inode->i_sb) +
4998                          EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb)) + 3);
4999                 if (IS_ERR(handle)) {
5000                         error = PTR_ERR(handle);
5001                         goto err_out;
5002                 }
5003                 error = dquot_transfer(inode, attr);
5004                 if (error) {
5005                         ext4_journal_stop(handle);
5006                         return error;
5007                 }
5008                 /* Update corresponding info in inode so that everything is in
5009                  * one transaction */
5010                 if (attr->ia_valid & ATTR_UID)
5011                         inode->i_uid = attr->ia_uid;
5012                 if (attr->ia_valid & ATTR_GID)
5013                         inode->i_gid = attr->ia_gid;
5014                 error = ext4_mark_inode_dirty(handle, inode);
5015                 ext4_journal_stop(handle);
5016         }
5017 
5018         if (attr->ia_valid & ATTR_SIZE) {
5019                 handle_t *handle;
5020                 loff_t oldsize = inode->i_size;
5021                 int shrink = (attr->ia_size <= inode->i_size);
5022 
5023                 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
5024                         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
5025 
5026                         if (attr->ia_size > sbi->s_bitmap_maxbytes)
5027                                 return -EFBIG;
5028                 }
5029                 if (!S_ISREG(inode->i_mode))
5030                         return -EINVAL;
5031 
5032                 if (IS_I_VERSION(inode) && attr->ia_size != inode->i_size)
5033                         inode_inc_iversion(inode);
5034 
5035                 if (ext4_should_order_data(inode) &&
5036                     (attr->ia_size < inode->i_size)) {
5037                         error = ext4_begin_ordered_truncate(inode,
5038                                                             attr->ia_size);
5039                         if (error)
5040                                 goto err_out;
5041                 }
5042                 if (attr->ia_size != inode->i_size) {
5043                         handle = ext4_journal_start(inode, EXT4_HT_INODE, 3);
5044                         if (IS_ERR(handle)) {
5045                                 error = PTR_ERR(handle);
5046                                 goto err_out;
5047                         }
5048                         if (ext4_handle_valid(handle) && shrink) {
5049                                 error = ext4_orphan_add(handle, inode);
5050                                 orphan = 1;
5051                         }
5052                         /*
5053                          * Update c/mtime on truncate up, ext4_truncate() will
5054                          * update c/mtime in shrink case below
5055                          */
5056                         if (!shrink) {
5057                                 inode->i_mtime = ext4_current_time(inode);
5058                                 inode->i_ctime = inode->i_mtime;
5059                         }
5060                         down_write(&EXT4_I(inode)->i_data_sem);
5061                         EXT4_I(inode)->i_disksize = attr->ia_size;
5062                         rc = ext4_mark_inode_dirty(handle, inode);
5063                         if (!error)
5064                                 error = rc;
5065                         /*
5066                          * We have to update i_size under i_data_sem together
5067                          * with i_disksize to avoid races with writeback code
5068                          * running ext4_wb_update_i_disksize().
5069                          */
5070                         if (!error)
5071                                 i_size_write(inode, attr->ia_size);
5072                         up_write(&EXT4_I(inode)->i_data_sem);
5073                         ext4_journal_stop(handle);
5074                         if (error) {
5075                                 if (orphan)
5076                                         ext4_orphan_del(NULL, inode);
5077                                 goto err_out;
5078                         }
5079                 }
5080                 if (!shrink)
5081                         pagecache_isize_extended(inode, oldsize, inode->i_size);
5082 
5083                 /*
5084                  * Blocks are going to be removed from the inode. Wait
5085                  * for dio in flight.  Temporarily disable
5086                  * dioread_nolock to prevent livelock.
5087                  */
5088                 if (orphan) {
5089                         if (!ext4_should_journal_data(inode)) {
5090                                 ext4_inode_block_unlocked_dio(inode);
5091                                 inode_dio_wait(inode);
5092                                 ext4_inode_resume_unlocked_dio(inode);
5093                         } else
5094                                 ext4_wait_for_tail_page_commit(inode);
5095                 }
5096                 down_write(&EXT4_I(inode)->i_mmap_sem);
5097                 /*
5098                  * Truncate pagecache after we've waited for commit
5099                  * in data=journal mode to make pages freeable.
5100                  */
5101                 truncate_pagecache(inode, inode->i_size);
5102                 if (shrink)
5103                         ext4_truncate(inode);
5104                 up_write(&EXT4_I(inode)->i_mmap_sem);
5105         }
5106 
5107         if (!rc) {
5108                 setattr_copy(inode, attr);
5109                 mark_inode_dirty(inode);
5110         }
5111 
5112         /*
5113          * If the call to ext4_truncate failed to get a transaction handle at
5114          * all, we need to clean up the in-core orphan list manually.
5115          */
5116         if (orphan && inode->i_nlink)
5117                 ext4_orphan_del(NULL, inode);
5118 
5119         if (!rc && (ia_valid & ATTR_MODE))
5120                 rc = posix_acl_chmod(inode, inode->i_mode);
5121 
5122 err_out:
5123         ext4_std_error(inode->i_sb, error);
5124         if (!error)
5125                 error = rc;
5126         return error;
5127 }
5128 
5129 int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry,
5130                  struct kstat *stat)
5131 {
5132         struct inode *inode;
5133         unsigned long long delalloc_blocks;
5134 
5135         inode = d_inode(dentry);
5136         generic_fillattr(inode, stat);
5137 
5138         /*
5139          * If there is inline data in the inode, the inode will normally not
5140          * have data blocks allocated (it may have an external xattr block).
5141          * Report at least one sector for such files, so tools like tar, rsync,
5142          * others doen't incorrectly think the file is completely sparse.
5143          */
5144         if (unlikely(ext4_has_inline_data(inode)))
5145                 stat->blocks += (stat->size + 511) >> 9;
5146 
5147         /*
5148          * We can't update i_blocks if the block allocation is delayed
5149          * otherwise in the case of system crash before the real block
5150          * allocation is done, we will have i_blocks inconsistent with
5151          * on-disk file blocks.
5152          * We always keep i_blocks updated together with real
5153          * allocation. But to not confuse with user, stat
5154          * will return the blocks that include the delayed allocation
5155          * blocks for this file.
5156          */
5157         delalloc_blocks = EXT4_C2B(EXT4_SB(inode->i_sb),
5158                                    EXT4_I(inode)->i_reserved_data_blocks);
5159         stat->blocks += delalloc_blocks << (inode->i_sb->s_blocksize_bits - 9);
5160         return 0;
5161 }
5162 
5163 static int ext4_index_trans_blocks(struct inode *inode, int lblocks,
5164                                    int pextents)
5165 {
5166         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
5167                 return ext4_ind_trans_blocks(inode, lblocks);
5168         return ext4_ext_index_trans_blocks(inode, pextents);
5169 }
5170 
5171 /*
5172  * Account for index blocks, block groups bitmaps and block group
5173  * descriptor blocks if modify datablocks and index blocks
5174  * worse case, the indexs blocks spread over different block groups
5175  *
5176  * If datablocks are discontiguous, they are possible to spread over
5177  * different block groups too. If they are contiguous, with flexbg,
5178  * they could still across block group boundary.
5179  *
5180  * Also account for superblock, inode, quota and xattr blocks
5181  */
5182 static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
5183                                   int pextents)
5184 {
5185         ext4_group_t groups, ngroups = ext4_get_groups_count(inode->i_sb);
5186         int gdpblocks;
5187         int idxblocks;
5188         int ret = 0;
5189 
5190         /*
5191          * How many index blocks need to touch to map @lblocks logical blocks
5192          * to @pextents physical extents?
5193          */
5194         idxblocks = ext4_index_trans_blocks(inode, lblocks, pextents);
5195 
5196         ret = idxblocks;
5197 
5198         /*
5199          * Now let's see how many group bitmaps and group descriptors need
5200          * to account
5201          */
5202         groups = idxblocks + pextents;
5203         gdpblocks = groups;
5204         if (groups > ngroups)
5205                 groups = ngroups;
5206         if (groups > EXT4_SB(inode->i_sb)->s_gdb_count)
5207                 gdpblocks = EXT4_SB(inode->i_sb)->s_gdb_count;
5208 
5209         /* bitmaps and block group descriptor blocks */
5210         ret += groups + gdpblocks;
5211 
5212         /* Blocks for super block, inode, quota and xattr blocks */
5213         ret += EXT4_META_TRANS_BLOCKS(inode->i_sb);
5214 
5215         return ret;
5216 }
5217 
5218 /*
5219  * Calculate the total number of credits to reserve to fit
5220  * the modification of a single pages into a single transaction,
5221  * which may include multiple chunks of block allocations.
5222  *
5223  * This could be called via ext4_write_begin()
5224  *
5225  * We need to consider the worse case, when
5226  * one new block per extent.
5227  */
5228 int ext4_writepage_trans_blocks(struct inode *inode)
5229 {
5230         int bpp = ext4_journal_blocks_per_page(inode);
5231         int ret;
5232 
5233         ret = ext4_meta_trans_blocks(inode, bpp, bpp);
5234 
5235         /* Account for data blocks for journalled mode */
5236         if (ext4_should_journal_data(inode))
5237                 ret += bpp;
5238         return ret;
5239 }
5240 
5241 /*
5242  * Calculate the journal credits for a chunk of data modification.
5243  *
5244  * This is called from DIO, fallocate or whoever calling
5245  * ext4_map_blocks() to map/allocate a chunk of contiguous disk blocks.
5246  *
5247  * journal buffers for data blocks are not included here, as DIO
5248  * and fallocate do no need to journal data buffers.
5249  */
5250 int ext4_chunk_trans_blocks(struct inode *inode, int nrblocks)
5251 {
5252         return ext4_meta_trans_blocks(inode, nrblocks, 1);
5253 }
5254 
5255 /*
5256  * The caller must have previously called ext4_reserve_inode_write().
5257  * Give this, we know that the caller already has write access to iloc->bh.
5258  */
5259 int ext4_mark_iloc_dirty(handle_t *handle,
5260                          struct inode *inode, struct ext4_iloc *iloc)
5261 {
5262         int err = 0;
5263 
5264         if (IS_I_VERSION(inode))
5265                 inode_inc_iversion(inode);
5266 
5267         /* the do_update_inode consumes one bh->b_count */
5268         get_bh(iloc->bh);
5269 
5270         /* ext4_do_update_inode() does jbd2_journal_dirty_metadata */
5271         err = ext4_do_update_inode(handle, inode, iloc);
5272         put_bh(iloc->bh);
5273         return err;
5274 }
5275 
5276 /*
5277  * On success, We end up with an outstanding reference count against
5278  * iloc->bh.  This _must_ be cleaned up later.
5279  */
5280 
5281 int
5282 ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
5283                          struct ext4_iloc *iloc)
5284 {
5285         int err;
5286 
5287         err = ext4_get_inode_loc(inode, iloc);
5288         if (!err) {
5289                 BUFFER_TRACE(iloc->bh, "get_write_access");
5290                 err = ext4_journal_get_write_access(handle, iloc->bh);
5291                 if (err) {
5292                         brelse(iloc->bh);
5293                         iloc->bh = NULL;
5294                 }
5295         }
5296         ext4_std_error(inode->i_sb, err);
5297         return err;
5298 }
5299 
5300 /*
5301  * Expand an inode by new_extra_isize bytes.
5302  * Returns 0 on success or negative error number on failure.
5303  */
5304 static int ext4_expand_extra_isize(struct inode *inode,
5305                                    unsigned int new_extra_isize,
5306                                    struct ext4_iloc iloc,
5307                                    handle_t *handle)
5308 {
5309         struct ext4_inode *raw_inode;
5310         struct ext4_xattr_ibody_header *header;
5311 
5312         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
5313                 return 0;
5314 
5315         raw_inode = ext4_raw_inode(&iloc);
5316 
5317         header = IHDR(inode, raw_inode);
5318 
5319         /* No extended attributes present */
5320         if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR) ||
5321             header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)) {
5322                 memset((void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE, 0,
5323                         new_extra_isize);
5324                 EXT4_I(inode)->i_extra_isize = new_extra_isize;
5325                 return 0;
5326         }
5327 
5328         /* try to expand with EAs present */
5329         return ext4_expand_extra_isize_ea(inode, new_extra_isize,
5330                                           raw_inode, handle);
5331 }
5332 
5333 /*
5334  * What we do here is to mark the in-core inode as clean with respect to inode
5335  * dirtiness (it may still be data-dirty).
5336  * This means that the in-core inode may be reaped by prune_icache
5337  * without having to perform any I/O.  This is a very good thing,
5338  * because *any* task may call prune_icache - even ones which
5339  * have a transaction open against a different journal.
5340  *
5341  * Is this cheating?  Not really.  Sure, we haven't written the
5342  * inode out, but prune_icache isn't a user-visible syncing function.
5343  * Whenever the user wants stuff synced (sys_sync, sys_msync, sys_fsync)
5344  * we start and wait on commits.
5345  */
5346 int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
5347 {
5348         struct ext4_iloc iloc;
5349         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
5350         static unsigned int mnt_count;
5351         int err, ret;
5352 
5353         might_sleep();
5354         trace_ext4_mark_inode_dirty(inode, _RET_IP_);
5355         err = ext4_reserve_inode_write(handle, inode, &iloc);
5356         if (err)
5357                 return err;
5358         if (ext4_handle_valid(handle) &&
5359             EXT4_I(inode)->i_extra_isize < sbi->s_want_extra_isize &&
5360             !ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND)) {
5361                 /*
5362                  * We need extra buffer credits since we may write into EA block
5363                  * with this same handle. If journal_extend fails, then it will
5364                  * only result in a minor loss of functionality for that inode.
5365                  * If this is felt to be critical, then e2fsck should be run to
5366                  * force a large enough s_min_extra_isize.
5367                  */
5368                 if ((jbd2_journal_extend(handle,
5369                              EXT4_DATA_TRANS_BLOCKS(inode->i_sb))) == 0) {
5370                         ret = ext4_expand_extra_isize(inode,
5371                                                       sbi->s_want_extra_isize,
5372                                                       iloc, handle);
5373                         if (ret) {
5374                                 ext4_set_inode_state(inode,
5375                                                      EXT4_STATE_NO_EXPAND);
5376                                 if (mnt_count !=
5377                                         le16_to_cpu(sbi->s_es->s_mnt_count)) {
5378                                         ext4_warning(inode->i_sb,
5379                                         "Unable to expand inode %lu. Delete"
5380                                         " some EAs or run e2fsck.",
5381                                         inode->i_ino);
5382                                         mnt_count =
5383                                           le16_to_cpu(sbi->s_es->s_mnt_count);
5384                                 }
5385                         }
5386                 }
5387         }
5388         return ext4_mark_iloc_dirty(handle, inode, &iloc);
5389 }
5390 
5391 /*
5392  * ext4_dirty_inode() is called from __mark_inode_dirty()
5393  *
5394  * We're really interested in the case where a file is being extended.
5395  * i_size has been changed by generic_commit_write() and we thus need
5396  * to include the updated inode in the current transaction.
5397  *
5398  * Also, dquot_alloc_block() will always dirty the inode when blocks
5399  * are allocated to the file.
5400  *
5401  * If the inode is marked synchronous, we don't honour that here - doing
5402  * so would cause a commit on atime updates, which we don't bother doing.
5403  * We handle synchronous inodes at the highest possible level.
5404  *
5405  * If only the I_DIRTY_TIME flag is set, we can skip everything.  If
5406  * I_DIRTY_TIME and I_DIRTY_SYNC is set, the only inode fields we need
5407  * to copy into the on-disk inode structure are the timestamp files.
5408  */
5409 void ext4_dirty_inode(struct inode *inode, int flags)
5410 {
5411         handle_t *handle;
5412 
5413         if (flags == I_DIRTY_TIME)
5414                 return;
5415         handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
5416         if (IS_ERR(handle))
5417                 goto out;
5418 
5419         ext4_mark_inode_dirty(handle, inode);
5420 
5421         ext4_journal_stop(handle);
5422 out:
5423         return;
5424 }
5425 
5426 #if 0
5427 /*
5428  * Bind an inode's backing buffer_head into this transaction, to prevent
5429  * it from being flushed to disk early.  Unlike
5430  * ext4_reserve_inode_write, this leaves behind no bh reference and
5431  * returns no iloc structure, so the caller needs to repeat the iloc
5432  * lookup to mark the inode dirty later.
5433  */
5434 static int ext4_pin_inode(handle_t *handle, struct inode *inode)
5435 {
5436         struct ext4_iloc iloc;
5437 
5438         int err = 0;
5439         if (handle) {
5440                 err = ext4_get_inode_loc(inode, &iloc);
5441                 if (!err) {
5442                         BUFFER_TRACE(iloc.bh, "get_write_access");
5443                         err = jbd2_journal_get_write_access(handle, iloc.bh);
5444                         if (!err)
5445                                 err = ext4_handle_dirty_metadata(handle,
5446                                                                  NULL,
5447                                                                  iloc.bh);
5448                         brelse(iloc.bh);
5449                 }
5450         }
5451         ext4_std_error(inode->i_sb, err);
5452         return err;
5453 }
5454 #endif
5455 
5456 int ext4_change_inode_journal_flag(struct inode *inode, int val)
5457 {
5458         journal_t *journal;
5459         handle_t *handle;
5460         int err;
5461 
5462         /*
5463          * We have to be very careful here: changing a data block's
5464          * journaling status dynamically is dangerous.  If we write a
5465          * data block to the journal, change the status and then delete
5466          * that block, we risk forgetting to revoke the old log record
5467          * from the journal and so a subsequent replay can corrupt data.
5468          * So, first we make sure that the journal is empty and that
5469          * nobody is changing anything.
5470          */
5471 
5472         journal = EXT4_JOURNAL(inode);
5473         if (!journal)
5474                 return 0;
5475         if (is_journal_aborted(journal))
5476                 return -EROFS;
5477         /* We have to allocate physical blocks for delalloc blocks
5478          * before flushing journal. otherwise delalloc blocks can not
5479          * be allocated any more. even more truncate on delalloc blocks
5480          * could trigger BUG by flushing delalloc blocks in journal.
5481          * There is no delalloc block in non-journal data mode.
5482          */
5483         if (val && test_opt(inode->i_sb, DELALLOC)) {
5484                 err = ext4_alloc_da_blocks(inode);
5485                 if (err < 0)
5486                         return err;
5487         }
5488 
5489         /* Wait for all existing dio workers */
5490         ext4_inode_block_unlocked_dio(inode);
5491         inode_dio_wait(inode);
5492 
5493         jbd2_journal_lock_updates(journal);
5494 
5495         /*
5496          * OK, there are no updates running now, and all cached data is
5497          * synced to disk.  We are now in a completely consistent state
5498          * which doesn't have anything in the journal, and we know that
5499          * no filesystem updates are running, so it is safe to modify
5500          * the inode's in-core data-journaling state flag now.
5501          */
5502 
5503         if (val)
5504                 ext4_set_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
5505         else {
5506                 err = jbd2_journal_flush(journal);
5507                 if (err < 0) {
5508                         jbd2_journal_unlock_updates(journal);
5509                         ext4_inode_resume_unlocked_dio(inode);
5510                         return err;
5511                 }
5512                 ext4_clear_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
5513         }
5514         ext4_set_aops(inode);
5515 
5516         jbd2_journal_unlock_updates(journal);
5517         ext4_inode_resume_unlocked_dio(inode);
5518 
5519         /* Finally we can mark the inode as dirty. */
5520 
5521         handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
5522         if (IS_ERR(handle))
5523                 return PTR_ERR(handle);
5524 
5525         err = ext4_mark_inode_dirty(handle, inode);
5526         ext4_handle_sync(handle);
5527         ext4_journal_stop(handle);
5528         ext4_std_error(inode->i_sb, err);
5529 
5530         return err;
5531 }
5532 
5533 static int ext4_bh_unmapped(handle_t *handle, struct buffer_head *bh)
5534 {
5535         return !buffer_mapped(bh);
5536 }
5537 
5538 int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
5539 {
5540         struct page *page = vmf->page;
5541         loff_t size;
5542         unsigned long len;
5543         int ret;
5544         struct file *file = vma->vm_file;
5545         struct inode *inode = file_inode(file);
5546         struct address_space *mapping = inode->i_mapping;
5547         handle_t *handle;
5548         get_block_t *get_block;
5549         int retries = 0;
5550 
5551         sb_start_pagefault(inode->i_sb);
5552         file_update_time(vma->vm_file);
5553 
5554         down_read(&EXT4_I(inode)->i_mmap_sem);
5555         /* Delalloc case is easy... */
5556         if (test_opt(inode->i_sb, DELALLOC) &&
5557             !ext4_should_journal_data(inode) &&
5558             !ext4_nonda_switch(inode->i_sb)) {
5559                 do {
5560                         ret = block_page_mkwrite(vma, vmf,
5561                                                    ext4_da_get_block_prep);
5562                 } while (ret == -ENOSPC &&
5563                        ext4_should_retry_alloc(inode->i_sb, &retries));
5564                 goto out_ret;
5565         }
5566 
5567         lock_page(page);
5568         size = i_size_read(inode);
5569         /* Page got truncated from under us? */
5570         if (page->mapping != mapping || page_offset(page) > size) {
5571                 unlock_page(page);
5572                 ret = VM_FAULT_NOPAGE;
5573                 goto out;
5574         }
5575 
5576         if (page->index == size >> PAGE_SHIFT)
5577                 len = size & ~PAGE_MASK;
5578         else
5579                 len = PAGE_SIZE;
5580         /*
5581          * Return if we have all the buffers mapped. This avoids the need to do
5582          * journal_start/journal_stop which can block and take a long time
5583          */
5584         if (page_has_buffers(page)) {
5585                 if (!ext4_walk_page_buffers(NULL, page_buffers(page),
5586                                             0, len, NULL,
5587                                             ext4_bh_unmapped)) {
5588                         /* Wait so that we don't change page under IO */
5589                         wait_for_stable_page(page);
5590                         ret = VM_FAULT_LOCKED;
5591                         goto out;
5592                 }
5593         }
5594         unlock_page(page);
5595         /* OK, we need to fill the hole... */
5596         if (ext4_should_dioread_nolock(inode))
5597                 get_block = ext4_get_block_unwritten;
5598         else
5599                 get_block = ext4_get_block;
5600 retry_alloc:
5601         handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
5602                                     ext4_writepage_trans_blocks(inode));
5603         if (IS_ERR(handle)) {
5604                 ret = VM_FAULT_SIGBUS;
5605                 goto out;
5606         }
5607         ret = block_page_mkwrite(vma, vmf, get_block);
5608         if (!ret && ext4_should_journal_data(inode)) {
5609                 if (ext4_walk_page_buffers(handle, page_buffers(page), 0,
5610                           PAGE_SIZE, NULL, do_journal_get_write_access)) {
5611                         unlock_page(page);
5612                         ret = VM_FAULT_SIGBUS;
5613                         ext4_journal_stop(handle);
5614                         goto out;
5615                 }
5616                 ext4_set_inode_state(inode, EXT4_STATE_JDATA);
5617         }
5618         ext4_journal_stop(handle);
5619         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
5620                 goto retry_alloc;
5621 out_ret:
5622         ret = block_page_mkwrite_return(ret);
5623 out:
5624         up_read(&EXT4_I(inode)->i_mmap_sem);
5625         sb_end_pagefault(inode->i_sb);
5626         return ret;
5627 }
5628 
5629 int ext4_filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
5630 {
5631         struct inode *inode = file_inode(vma->vm_file);
5632         int err;
5633 
5634         down_read(&EXT4_I(inode)->i_mmap_sem);
5635         err = filemap_fault(vma, vmf);
5636         up_read(&EXT4_I(inode)->i_mmap_sem);
5637 
5638         return err;
5639 }
5640 
5641 /*
5642  * Find the first extent at or after @lblk in an inode that is not a hole.
5643  * Search for @map_len blocks at most. The extent is returned in @result.
5644  *
5645  * The function returns 1 if we found an extent. The function returns 0 in
5646  * case there is no extent at or after @lblk and in that case also sets
5647  * @result->es_len to 0. In case of error, the error code is returned.
5648  */
5649 int ext4_get_next_extent(struct inode *inode, ext4_lblk_t lblk,
5650                          unsigned int map_len, struct extent_status *result)
5651 {
5652         struct ext4_map_blocks map;
5653         struct extent_status es = {};
5654         int ret;
5655 
5656         map.m_lblk = lblk;
5657         map.m_len = map_len;
5658 
5659         /*
5660          * For non-extent based files this loop may iterate several times since
5661          * we do not determine full hole size.
5662          */
5663         while (map.m_len > 0) {
5664                 ret = ext4_map_blocks(NULL, inode, &map, 0);
5665                 if (ret < 0)
5666                         return ret;
5667                 /* There's extent covering m_lblk? Just return it. */
5668                 if (ret > 0) {
5669                         int status;
5670 
5671                         ext4_es_store_pblock(result, map.m_pblk);
5672                         result->es_lblk = map.m_lblk;
5673                         result->es_len = map.m_len;
5674                         if (map.m_flags & EXT4_MAP_UNWRITTEN)
5675                                 status = EXTENT_STATUS_UNWRITTEN;
5676                         else
5677                                 status = EXTENT_STATUS_WRITTEN;
5678                         ext4_es_store_status(result, status);
5679                         return 1;
5680                 }
5681                 ext4_es_find_delayed_extent_range(inode, map.m_lblk,
5682                                                   map.m_lblk + map.m_len - 1,
5683                                                   &es);
5684                 /* Is delalloc data before next block in extent tree? */
5685                 if (es.es_len && es.es_lblk < map.m_lblk + map.m_len) {
5686                         ext4_lblk_t offset = 0;
5687 
5688                         if (es.es_lblk < lblk)
5689                                 offset = lblk - es.es_lblk;
5690                         result->es_lblk = es.es_lblk + offset;
5691                         ext4_es_store_pblock(result,
5692                                              ext4_es_pblock(&es) + offset);
5693                         result->es_len = es.es_len - offset;
5694                         ext4_es_store_status(result, ext4_es_status(&es));
5695 
5696                         return 1;
5697                 }
5698                 /* There's a hole at m_lblk, advance us after it */
5699                 map.m_lblk += map.m_len;
5700                 map_len -= map.m_len;
5701                 map.m_len = map_len;
5702                 cond_resched();
5703         }
5704         result->es_len = 0;
5705         return 0;
5706 }
5707 

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