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

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  1 /*
  2  *  linux/fs/ext4/file.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/file.c
 12  *
 13  *  Copyright (C) 1991, 1992  Linus Torvalds
 14  *
 15  *  ext4 fs regular file handling primitives
 16  *
 17  *  64-bit file support on 64-bit platforms by Jakub Jelinek
 18  *      (jj@sunsite.ms.mff.cuni.cz)
 19  */
 20 
 21 #include <linux/time.h>
 22 #include <linux/fs.h>
 23 #include <linux/mount.h>
 24 #include <linux/path.h>
 25 #include <linux/dax.h>
 26 #include <linux/quotaops.h>
 27 #include <linux/pagevec.h>
 28 #include <linux/uio.h>
 29 #include "ext4.h"
 30 #include "ext4_jbd2.h"
 31 #include "xattr.h"
 32 #include "acl.h"
 33 
 34 /*
 35  * Called when an inode is released. Note that this is different
 36  * from ext4_file_open: open gets called at every open, but release
 37  * gets called only when /all/ the files are closed.
 38  */
 39 static int ext4_release_file(struct inode *inode, struct file *filp)
 40 {
 41         if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
 42                 ext4_alloc_da_blocks(inode);
 43                 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
 44         }
 45         /* if we are the last writer on the inode, drop the block reservation */
 46         if ((filp->f_mode & FMODE_WRITE) &&
 47                         (atomic_read(&inode->i_writecount) == 1) &&
 48                         !EXT4_I(inode)->i_reserved_data_blocks)
 49         {
 50                 down_write(&EXT4_I(inode)->i_data_sem);
 51                 ext4_discard_preallocations(inode);
 52                 up_write(&EXT4_I(inode)->i_data_sem);
 53         }
 54         if (is_dx(inode) && filp->private_data)
 55                 ext4_htree_free_dir_info(filp->private_data);
 56 
 57         return 0;
 58 }
 59 
 60 static void ext4_unwritten_wait(struct inode *inode)
 61 {
 62         wait_queue_head_t *wq = ext4_ioend_wq(inode);
 63 
 64         wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_unwritten) == 0));
 65 }
 66 
 67 /*
 68  * This tests whether the IO in question is block-aligned or not.
 69  * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
 70  * are converted to written only after the IO is complete.  Until they are
 71  * mapped, these blocks appear as holes, so dio_zero_block() will assume that
 72  * it needs to zero out portions of the start and/or end block.  If 2 AIO
 73  * threads are at work on the same unwritten block, they must be synchronized
 74  * or one thread will zero the other's data, causing corruption.
 75  */
 76 static int
 77 ext4_unaligned_aio(struct inode *inode, struct iov_iter *from, loff_t pos)
 78 {
 79         struct super_block *sb = inode->i_sb;
 80         int blockmask = sb->s_blocksize - 1;
 81 
 82         if (pos >= ALIGN(i_size_read(inode), sb->s_blocksize))
 83                 return 0;
 84 
 85         if ((pos | iov_iter_alignment(from)) & blockmask)
 86                 return 1;
 87 
 88         return 0;
 89 }
 90 
 91 static ssize_t
 92 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 93 {
 94         struct file *file = iocb->ki_filp;
 95         struct inode *inode = file_inode(iocb->ki_filp);
 96         struct mutex *aio_mutex = NULL;
 97         struct blk_plug plug;
 98         int o_direct = iocb->ki_flags & IOCB_DIRECT;
 99         int overwrite = 0;
100         ssize_t ret;
101 
102         /*
103          * Unaligned direct AIO must be serialized; see comment above
104          * In the case of O_APPEND, assume that we must always serialize
105          */
106         if (o_direct &&
107             ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
108             !is_sync_kiocb(iocb) &&
109             (iocb->ki_flags & IOCB_APPEND ||
110              ext4_unaligned_aio(inode, from, iocb->ki_pos))) {
111                 aio_mutex = ext4_aio_mutex(inode);
112                 mutex_lock(aio_mutex);
113                 ext4_unwritten_wait(inode);
114         }
115 
116         mutex_lock(&inode->i_mutex);
117         ret = generic_write_checks(iocb, from);
118         if (ret <= 0)
119                 goto out;
120 
121         /*
122          * If we have encountered a bitmap-format file, the size limit
123          * is smaller than s_maxbytes, which is for extent-mapped files.
124          */
125         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
126                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
127 
128                 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes) {
129                         ret = -EFBIG;
130                         goto out;
131                 }
132                 iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
133         }
134 
135         iocb->private = &overwrite;
136         if (o_direct) {
137                 size_t length = iov_iter_count(from);
138                 loff_t pos = iocb->ki_pos;
139                 blk_start_plug(&plug);
140 
141                 /* check whether we do a DIO overwrite or not */
142                 if (ext4_should_dioread_nolock(inode) && !aio_mutex &&
143                     !file->f_mapping->nrpages && pos + length <= i_size_read(inode)) {
144                         struct ext4_map_blocks map;
145                         unsigned int blkbits = inode->i_blkbits;
146                         int err, len;
147 
148                         map.m_lblk = pos >> blkbits;
149                         map.m_len = (EXT4_BLOCK_ALIGN(pos + length, blkbits) >> blkbits)
150                                 - map.m_lblk;
151                         len = map.m_len;
152 
153                         err = ext4_map_blocks(NULL, inode, &map, 0);
154                         /*
155                          * 'err==len' means that all of blocks has
156                          * been preallocated no matter they are
157                          * initialized or not.  For excluding
158                          * unwritten extents, we need to check
159                          * m_flags.  There are two conditions that
160                          * indicate for initialized extents.  1) If we
161                          * hit extent cache, EXT4_MAP_MAPPED flag is
162                          * returned; 2) If we do a real lookup,
163                          * non-flags are returned.  So we should check
164                          * these two conditions.
165                          */
166                         if (err == len && (map.m_flags & EXT4_MAP_MAPPED))
167                                 overwrite = 1;
168                 }
169         }
170 
171         ret = __generic_file_write_iter(iocb, from);
172         mutex_unlock(&inode->i_mutex);
173 
174         if (ret > 0) {
175                 ssize_t err;
176 
177                 err = generic_write_sync(file, iocb->ki_pos - ret, ret);
178                 if (err < 0)
179                         ret = err;
180         }
181         if (o_direct)
182                 blk_finish_plug(&plug);
183 
184         if (aio_mutex)
185                 mutex_unlock(aio_mutex);
186         return ret;
187 
188 out:
189         mutex_unlock(&inode->i_mutex);
190         if (aio_mutex)
191                 mutex_unlock(aio_mutex);
192         return ret;
193 }
194 
195 #ifdef CONFIG_FS_DAX
196 static void ext4_end_io_unwritten(struct buffer_head *bh, int uptodate)
197 {
198         struct inode *inode = bh->b_assoc_map->host;
199         /* XXX: breaks on 32-bit > 16TB. Is that even supported? */
200         loff_t offset = (loff_t)(uintptr_t)bh->b_private << inode->i_blkbits;
201         int err;
202         if (!uptodate)
203                 return;
204         WARN_ON(!buffer_unwritten(bh));
205         err = ext4_convert_unwritten_extents(NULL, inode, offset, bh->b_size);
206 }
207 
208 static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
209 {
210         int result;
211         handle_t *handle = NULL;
212         struct inode *inode = file_inode(vma->vm_file);
213         struct super_block *sb = inode->i_sb;
214         bool write = vmf->flags & FAULT_FLAG_WRITE;
215 
216         if (write) {
217                 sb_start_pagefault(sb);
218                 file_update_time(vma->vm_file);
219                 down_read(&EXT4_I(inode)->i_mmap_sem);
220                 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
221                                                 EXT4_DATA_TRANS_BLOCKS(sb));
222         } else
223                 down_read(&EXT4_I(inode)->i_mmap_sem);
224 
225         if (IS_ERR(handle))
226                 result = VM_FAULT_SIGBUS;
227         else
228                 result = __dax_fault(vma, vmf, ext4_get_block_dax,
229                                                 ext4_end_io_unwritten);
230 
231         if (write) {
232                 if (!IS_ERR(handle))
233                         ext4_journal_stop(handle);
234                 up_read(&EXT4_I(inode)->i_mmap_sem);
235                 sb_end_pagefault(sb);
236         } else
237                 up_read(&EXT4_I(inode)->i_mmap_sem);
238 
239         return result;
240 }
241 
242 static int ext4_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
243                                                 pmd_t *pmd, unsigned int flags)
244 {
245         int result;
246         handle_t *handle = NULL;
247         struct inode *inode = file_inode(vma->vm_file);
248         struct super_block *sb = inode->i_sb;
249         bool write = flags & FAULT_FLAG_WRITE;
250 
251         if (write) {
252                 sb_start_pagefault(sb);
253                 file_update_time(vma->vm_file);
254                 down_read(&EXT4_I(inode)->i_mmap_sem);
255                 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
256                                 ext4_chunk_trans_blocks(inode,
257                                                         PMD_SIZE / PAGE_SIZE));
258         } else
259                 down_read(&EXT4_I(inode)->i_mmap_sem);
260 
261         if (IS_ERR(handle))
262                 result = VM_FAULT_SIGBUS;
263         else
264                 result = __dax_pmd_fault(vma, addr, pmd, flags,
265                                 ext4_get_block_dax, ext4_end_io_unwritten);
266 
267         if (write) {
268                 if (!IS_ERR(handle))
269                         ext4_journal_stop(handle);
270                 up_read(&EXT4_I(inode)->i_mmap_sem);
271                 sb_end_pagefault(sb);
272         } else
273                 up_read(&EXT4_I(inode)->i_mmap_sem);
274 
275         return result;
276 }
277 
278 static int ext4_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
279 {
280         int err;
281         struct inode *inode = file_inode(vma->vm_file);
282 
283         sb_start_pagefault(inode->i_sb);
284         file_update_time(vma->vm_file);
285         down_read(&EXT4_I(inode)->i_mmap_sem);
286         err = __dax_mkwrite(vma, vmf, ext4_get_block_dax,
287                             ext4_end_io_unwritten);
288         up_read(&EXT4_I(inode)->i_mmap_sem);
289         sb_end_pagefault(inode->i_sb);
290 
291         return err;
292 }
293 
294 /*
295  * Handle write fault for VM_MIXEDMAP mappings. Similarly to ext4_dax_mkwrite()
296  * handler we check for races agaist truncate. Note that since we cycle through
297  * i_mmap_sem, we are sure that also any hole punching that began before we
298  * were called is finished by now and so if it included part of the file we
299  * are working on, our pte will get unmapped and the check for pte_same() in
300  * wp_pfn_shared() fails. Thus fault gets retried and things work out as
301  * desired.
302  */
303 static int ext4_dax_pfn_mkwrite(struct vm_area_struct *vma,
304                                 struct vm_fault *vmf)
305 {
306         struct inode *inode = file_inode(vma->vm_file);
307         struct super_block *sb = inode->i_sb;
308         int ret = VM_FAULT_NOPAGE;
309         loff_t size;
310 
311         sb_start_pagefault(sb);
312         file_update_time(vma->vm_file);
313         down_read(&EXT4_I(inode)->i_mmap_sem);
314         size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
315         if (vmf->pgoff >= size)
316                 ret = VM_FAULT_SIGBUS;
317         up_read(&EXT4_I(inode)->i_mmap_sem);
318         sb_end_pagefault(sb);
319 
320         return ret;
321 }
322 
323 static const struct vm_operations_struct ext4_dax_vm_ops = {
324         .fault          = ext4_dax_fault,
325         .pmd_fault      = ext4_dax_pmd_fault,
326         .page_mkwrite   = ext4_dax_mkwrite,
327         .pfn_mkwrite    = ext4_dax_pfn_mkwrite,
328 };
329 #else
330 #define ext4_dax_vm_ops ext4_file_vm_ops
331 #endif
332 
333 static const struct vm_operations_struct ext4_file_vm_ops = {
334         .fault          = ext4_filemap_fault,
335         .map_pages      = filemap_map_pages,
336         .page_mkwrite   = ext4_page_mkwrite,
337 };
338 
339 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
340 {
341         struct inode *inode = file->f_mapping->host;
342 
343         if (ext4_encrypted_inode(inode)) {
344                 int err = ext4_get_encryption_info(inode);
345                 if (err)
346                         return 0;
347                 if (ext4_encryption_info(inode) == NULL)
348                         return -ENOKEY;
349         }
350         file_accessed(file);
351         if (IS_DAX(file_inode(file))) {
352                 vma->vm_ops = &ext4_dax_vm_ops;
353                 vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
354         } else {
355                 vma->vm_ops = &ext4_file_vm_ops;
356         }
357         return 0;
358 }
359 
360 static int ext4_file_open(struct inode * inode, struct file * filp)
361 {
362         struct super_block *sb = inode->i_sb;
363         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
364         struct vfsmount *mnt = filp->f_path.mnt;
365         struct path path;
366         char buf[64], *cp;
367         int ret;
368 
369         if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
370                      !(sb->s_flags & MS_RDONLY))) {
371                 sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
372                 /*
373                  * Sample where the filesystem has been mounted and
374                  * store it in the superblock for sysadmin convenience
375                  * when trying to sort through large numbers of block
376                  * devices or filesystem images.
377                  */
378                 memset(buf, 0, sizeof(buf));
379                 path.mnt = mnt;
380                 path.dentry = mnt->mnt_root;
381                 cp = d_path(&path, buf, sizeof(buf));
382                 if (!IS_ERR(cp)) {
383                         handle_t *handle;
384                         int err;
385 
386                         handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
387                         if (IS_ERR(handle))
388                                 return PTR_ERR(handle);
389                         BUFFER_TRACE(sbi->s_sbh, "get_write_access");
390                         err = ext4_journal_get_write_access(handle, sbi->s_sbh);
391                         if (err) {
392                                 ext4_journal_stop(handle);
393                                 return err;
394                         }
395                         strlcpy(sbi->s_es->s_last_mounted, cp,
396                                 sizeof(sbi->s_es->s_last_mounted));
397                         ext4_handle_dirty_super(handle, sb);
398                         ext4_journal_stop(handle);
399                 }
400         }
401         if (ext4_encrypted_inode(inode)) {
402                 ret = ext4_get_encryption_info(inode);
403                 if (ret)
404                         return -EACCES;
405                 if (ext4_encryption_info(inode) == NULL)
406                         return -ENOKEY;
407         }
408         /*
409          * Set up the jbd2_inode if we are opening the inode for
410          * writing and the journal is present
411          */
412         if (filp->f_mode & FMODE_WRITE) {
413                 ret = ext4_inode_attach_jinode(inode);
414                 if (ret < 0)
415                         return ret;
416         }
417         return dquot_file_open(inode, filp);
418 }
419 
420 /*
421  * Here we use ext4_map_blocks() to get a block mapping for a extent-based
422  * file rather than ext4_ext_walk_space() because we can introduce
423  * SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same
424  * function.  When extent status tree has been fully implemented, it will
425  * track all extent status for a file and we can directly use it to
426  * retrieve the offset for SEEK_DATA/SEEK_HOLE.
427  */
428 
429 /*
430  * When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to
431  * lookup page cache to check whether or not there has some data between
432  * [startoff, endoff] because, if this range contains an unwritten extent,
433  * we determine this extent as a data or a hole according to whether the
434  * page cache has data or not.
435  */
436 static int ext4_find_unwritten_pgoff(struct inode *inode,
437                                      int whence,
438                                      struct ext4_map_blocks *map,
439                                      loff_t *offset)
440 {
441         struct pagevec pvec;
442         unsigned int blkbits;
443         pgoff_t index;
444         pgoff_t end;
445         loff_t endoff;
446         loff_t startoff;
447         loff_t lastoff;
448         int found = 0;
449 
450         blkbits = inode->i_sb->s_blocksize_bits;
451         startoff = *offset;
452         lastoff = startoff;
453         endoff = (loff_t)(map->m_lblk + map->m_len) << blkbits;
454 
455         index = startoff >> PAGE_CACHE_SHIFT;
456         end = endoff >> PAGE_CACHE_SHIFT;
457 
458         pagevec_init(&pvec, 0);
459         do {
460                 int i, num;
461                 unsigned long nr_pages;
462 
463                 num = min_t(pgoff_t, end - index, PAGEVEC_SIZE - 1) + 1;
464                 nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
465                                           (pgoff_t)num);
466                 if (nr_pages == 0)
467                         break;
468 
469                 for (i = 0; i < nr_pages; i++) {
470                         struct page *page = pvec.pages[i];
471                         struct buffer_head *bh, *head;
472 
473                         /*
474                          * If current offset is smaller than the page offset,
475                          * there is a hole at this offset.
476                          */
477                         if (whence == SEEK_HOLE && lastoff < endoff &&
478                             lastoff < page_offset(pvec.pages[i])) {
479                                 found = 1;
480                                 *offset = lastoff;
481                                 goto out;
482                         }
483 
484                         if (page->index > end)
485                                 goto out;
486 
487                         lock_page(page);
488 
489                         if (unlikely(page->mapping != inode->i_mapping)) {
490                                 unlock_page(page);
491                                 continue;
492                         }
493 
494                         if (!page_has_buffers(page)) {
495                                 unlock_page(page);
496                                 continue;
497                         }
498 
499                         if (page_has_buffers(page)) {
500                                 lastoff = page_offset(page);
501                                 bh = head = page_buffers(page);
502                                 do {
503                                         if (lastoff + bh->b_size <= startoff)
504                                                 goto next;
505                                         if (buffer_uptodate(bh) ||
506                                             buffer_unwritten(bh)) {
507                                                 if (whence == SEEK_DATA)
508                                                         found = 1;
509                                         } else {
510                                                 if (whence == SEEK_HOLE)
511                                                         found = 1;
512                                         }
513                                         if (found) {
514                                                 *offset = max_t(loff_t,
515                                                         startoff, lastoff);
516                                                 unlock_page(page);
517                                                 goto out;
518                                         }
519 next:
520                                         lastoff += bh->b_size;
521                                         bh = bh->b_this_page;
522                                 } while (bh != head);
523                         }
524 
525                         lastoff = page_offset(page) + PAGE_SIZE;
526                         unlock_page(page);
527                 }
528 
529                 /* The no. of pages is less than our desired, we are done. */
530                 if (nr_pages < num)
531                         break;
532 
533                 index = pvec.pages[i - 1]->index + 1;
534                 pagevec_release(&pvec);
535         } while (index <= end);
536 
537         if (whence == SEEK_HOLE && lastoff < endoff) {
538                 found = 1;
539                 *offset = lastoff;
540         }
541 out:
542         pagevec_release(&pvec);
543         return found;
544 }
545 
546 /*
547  * ext4_seek_data() retrieves the offset for SEEK_DATA.
548  */
549 static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
550 {
551         struct inode *inode = file->f_mapping->host;
552         struct ext4_map_blocks map;
553         struct extent_status es;
554         ext4_lblk_t start, last, end;
555         loff_t dataoff, isize;
556         int blkbits;
557         int ret = 0;
558 
559         mutex_lock(&inode->i_mutex);
560 
561         isize = i_size_read(inode);
562         if (offset < 0 || offset >= isize) {
563                 mutex_unlock(&inode->i_mutex);
564                 return -ENXIO;
565         }
566 
567         blkbits = inode->i_sb->s_blocksize_bits;
568         start = offset >> blkbits;
569         last = start;
570         end = isize >> blkbits;
571         dataoff = offset;
572 
573         do {
574                 map.m_lblk = last;
575                 map.m_len = end - last + 1;
576                 ret = ext4_map_blocks(NULL, inode, &map, 0);
577                 if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
578                         if (last != start)
579                                 dataoff = (loff_t)last << blkbits;
580                         break;
581                 }
582 
583                 /*
584                  * If there is a delay extent at this offset,
585                  * it will be as a data.
586                  */
587                 ext4_es_find_delayed_extent_range(inode, last, last, &es);
588                 if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) {
589                         if (last != start)
590                                 dataoff = (loff_t)last << blkbits;
591                         break;
592                 }
593 
594                 /*
595                  * If there is a unwritten extent at this offset,
596                  * it will be as a data or a hole according to page
597                  * cache that has data or not.
598                  */
599                 if (map.m_flags & EXT4_MAP_UNWRITTEN) {
600                         int unwritten;
601                         unwritten = ext4_find_unwritten_pgoff(inode, SEEK_DATA,
602                                                               &map, &dataoff);
603                         if (unwritten)
604                                 break;
605                 }
606 
607                 last++;
608                 dataoff = (loff_t)last << blkbits;
609         } while (last <= end);
610 
611         mutex_unlock(&inode->i_mutex);
612 
613         if (dataoff > isize)
614                 return -ENXIO;
615 
616         return vfs_setpos(file, dataoff, maxsize);
617 }
618 
619 /*
620  * ext4_seek_hole() retrieves the offset for SEEK_HOLE.
621  */
622 static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
623 {
624         struct inode *inode = file->f_mapping->host;
625         struct ext4_map_blocks map;
626         struct extent_status es;
627         ext4_lblk_t start, last, end;
628         loff_t holeoff, isize;
629         int blkbits;
630         int ret = 0;
631 
632         mutex_lock(&inode->i_mutex);
633 
634         isize = i_size_read(inode);
635         if (offset < 0 || offset >= isize) {
636                 mutex_unlock(&inode->i_mutex);
637                 return -ENXIO;
638         }
639 
640         blkbits = inode->i_sb->s_blocksize_bits;
641         start = offset >> blkbits;
642         last = start;
643         end = isize >> blkbits;
644         holeoff = offset;
645 
646         do {
647                 map.m_lblk = last;
648                 map.m_len = end - last + 1;
649                 ret = ext4_map_blocks(NULL, inode, &map, 0);
650                 if (ret > 0 && !(map.m_flags & EXT4_MAP_UNWRITTEN)) {
651                         last += ret;
652                         holeoff = (loff_t)last << blkbits;
653                         continue;
654                 }
655 
656                 /*
657                  * If there is a delay extent at this offset,
658                  * we will skip this extent.
659                  */
660                 ext4_es_find_delayed_extent_range(inode, last, last, &es);
661                 if (es.es_len != 0 && in_range(last, es.es_lblk, es.es_len)) {
662                         last = es.es_lblk + es.es_len;
663                         holeoff = (loff_t)last << blkbits;
664                         continue;
665                 }
666 
667                 /*
668                  * If there is a unwritten extent at this offset,
669                  * it will be as a data or a hole according to page
670                  * cache that has data or not.
671                  */
672                 if (map.m_flags & EXT4_MAP_UNWRITTEN) {
673                         int unwritten;
674                         unwritten = ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
675                                                               &map, &holeoff);
676                         if (!unwritten) {
677                                 last += ret;
678                                 holeoff = (loff_t)last << blkbits;
679                                 continue;
680                         }
681                 }
682 
683                 /* find a hole */
684                 break;
685         } while (last <= end);
686 
687         mutex_unlock(&inode->i_mutex);
688 
689         if (holeoff > isize)
690                 holeoff = isize;
691 
692         return vfs_setpos(file, holeoff, maxsize);
693 }
694 
695 /*
696  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
697  * by calling generic_file_llseek_size() with the appropriate maxbytes
698  * value for each.
699  */
700 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
701 {
702         struct inode *inode = file->f_mapping->host;
703         loff_t maxbytes;
704 
705         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
706                 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
707         else
708                 maxbytes = inode->i_sb->s_maxbytes;
709 
710         switch (whence) {
711         case SEEK_SET:
712         case SEEK_CUR:
713         case SEEK_END:
714                 return generic_file_llseek_size(file, offset, whence,
715                                                 maxbytes, i_size_read(inode));
716         case SEEK_DATA:
717                 return ext4_seek_data(file, offset, maxbytes);
718         case SEEK_HOLE:
719                 return ext4_seek_hole(file, offset, maxbytes);
720         }
721 
722         return -EINVAL;
723 }
724 
725 const struct file_operations ext4_file_operations = {
726         .llseek         = ext4_llseek,
727         .read_iter      = generic_file_read_iter,
728         .write_iter     = ext4_file_write_iter,
729         .unlocked_ioctl = ext4_ioctl,
730 #ifdef CONFIG_COMPAT
731         .compat_ioctl   = ext4_compat_ioctl,
732 #endif
733         .mmap           = ext4_file_mmap,
734         .open           = ext4_file_open,
735         .release        = ext4_release_file,
736         .fsync          = ext4_sync_file,
737         .splice_read    = generic_file_splice_read,
738         .splice_write   = iter_file_splice_write,
739         .fallocate      = ext4_fallocate,
740 };
741 
742 const struct inode_operations ext4_file_inode_operations = {
743         .setattr        = ext4_setattr,
744         .getattr        = ext4_getattr,
745         .setxattr       = generic_setxattr,
746         .getxattr       = generic_getxattr,
747         .listxattr      = ext4_listxattr,
748         .removexattr    = generic_removexattr,
749         .get_acl        = ext4_get_acl,
750         .set_acl        = ext4_set_acl,
751         .fiemap         = ext4_fiemap,
752 };
753 
754 

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