1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/ext4/file.c
4 *
5 * Copyright (C) 1992, 1993, 1994, 1995
6 * Remy Card (card@masi.ibp.fr)
7 * Laboratoire MASI - Institut Blaise Pascal
8 * Universite Pierre et Marie Curie (Paris VI)
9 *
10 * from
11 *
12 * linux/fs/minix/file.c
13 *
14 * Copyright (C) 1991, 1992 Linus Torvalds
15 *
16 * ext4 fs regular file handling primitives
17 *
18 * 64-bit file support on 64-bit platforms by Jakub Jelinek
19 * (jj@sunsite.ms.mff.cuni.cz)
20 */
21
22#include <linux/time.h>
23#include <linux/fs.h>
24#include <linux/iomap.h>
25#include <linux/mount.h>
26#include <linux/path.h>
27#include <linux/dax.h>
28#include <linux/quotaops.h>
29#include <linux/pagevec.h>
30#include <linux/uio.h>
31#include <linux/mman.h>
32#include <linux/backing-dev.h>
33#include "ext4.h"
34#include "ext4_jbd2.h"
35#include "xattr.h"
36#include "acl.h"
37#include "truncate.h"
38
39/*
40 * Returns %true if the given DIO request should be attempted with DIO, or
41 * %false if it should fall back to buffered I/O.
42 *
43 * DIO isn't well specified; when it's unsupported (either due to the request
44 * being misaligned, or due to the file not supporting DIO at all), filesystems
45 * either fall back to buffered I/O or return EINVAL. For files that don't use
46 * any special features like encryption or verity, ext4 has traditionally
47 * returned EINVAL for misaligned DIO. iomap_dio_rw() uses this convention too.
48 * In this case, we should attempt the DIO, *not* fall back to buffered I/O.
49 *
50 * In contrast, in cases where DIO is unsupported due to ext4 features, ext4
51 * traditionally falls back to buffered I/O.
52 *
53 * This function implements the traditional ext4 behavior in all these cases.
54 */
55static bool ext4_should_use_dio(struct kiocb *iocb, struct iov_iter *iter)
56{
57 struct inode *inode = file_inode(f: iocb->ki_filp);
58 u32 dio_align = ext4_dio_alignment(inode);
59
60 if (dio_align == 0)
61 return false;
62
63 if (dio_align == 1)
64 return true;
65
66 return IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(iter), dio_align);
67}
68
69static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
70{
71 ssize_t ret;
72 struct inode *inode = file_inode(f: iocb->ki_filp);
73
74 if (iocb->ki_flags & IOCB_NOWAIT) {
75 if (!inode_trylock_shared(inode))
76 return -EAGAIN;
77 } else {
78 inode_lock_shared(inode);
79 }
80
81 if (!ext4_should_use_dio(iocb, iter: to)) {
82 inode_unlock_shared(inode);
83 /*
84 * Fallback to buffered I/O if the operation being performed on
85 * the inode is not supported by direct I/O. The IOCB_DIRECT
86 * flag needs to be cleared here in order to ensure that the
87 * direct I/O path within generic_file_read_iter() is not
88 * taken.
89 */
90 iocb->ki_flags &= ~IOCB_DIRECT;
91 return generic_file_read_iter(iocb, to);
92 }
93
94 ret = iomap_dio_rw(iocb, iter: to, ops: &ext4_iomap_ops, NULL, dio_flags: 0, NULL, done_before: 0);
95 inode_unlock_shared(inode);
96
97 file_accessed(file: iocb->ki_filp);
98 return ret;
99}
100
101#ifdef CONFIG_FS_DAX
102static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
103{
104 struct inode *inode = file_inode(f: iocb->ki_filp);
105 ssize_t ret;
106
107 if (iocb->ki_flags & IOCB_NOWAIT) {
108 if (!inode_trylock_shared(inode))
109 return -EAGAIN;
110 } else {
111 inode_lock_shared(inode);
112 }
113 /*
114 * Recheck under inode lock - at this point we are sure it cannot
115 * change anymore
116 */
117 if (!IS_DAX(inode)) {
118 inode_unlock_shared(inode);
119 /* Fallback to buffered IO in case we cannot support DAX */
120 return generic_file_read_iter(iocb, to);
121 }
122 ret = dax_iomap_rw(iocb, iter: to, ops: &ext4_iomap_ops);
123 inode_unlock_shared(inode);
124
125 file_accessed(file: iocb->ki_filp);
126 return ret;
127}
128#endif
129
130static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
131{
132 struct inode *inode = file_inode(f: iocb->ki_filp);
133
134 if (unlikely(ext4_forced_shutdown(inode->i_sb)))
135 return -EIO;
136
137 if (!iov_iter_count(i: to))
138 return 0; /* skip atime */
139
140#ifdef CONFIG_FS_DAX
141 if (IS_DAX(inode))
142 return ext4_dax_read_iter(iocb, to);
143#endif
144 if (iocb->ki_flags & IOCB_DIRECT)
145 return ext4_dio_read_iter(iocb, to);
146
147 return generic_file_read_iter(iocb, to);
148}
149
150static ssize_t ext4_file_splice_read(struct file *in, loff_t *ppos,
151 struct pipe_inode_info *pipe,
152 size_t len, unsigned int flags)
153{
154 struct inode *inode = file_inode(f: in);
155
156 if (unlikely(ext4_forced_shutdown(inode->i_sb)))
157 return -EIO;
158 return filemap_splice_read(in, ppos, pipe, len, flags);
159}
160
161/*
162 * Called when an inode is released. Note that this is different
163 * from ext4_file_open: open gets called at every open, but release
164 * gets called only when /all/ the files are closed.
165 */
166static int ext4_release_file(struct inode *inode, struct file *filp)
167{
168 if (ext4_test_inode_state(inode, bit: EXT4_STATE_DA_ALLOC_CLOSE)) {
169 ext4_alloc_da_blocks(inode);
170 ext4_clear_inode_state(inode, bit: EXT4_STATE_DA_ALLOC_CLOSE);
171 }
172 /* if we are the last writer on the inode, drop the block reservation */
173 if ((filp->f_mode & FMODE_WRITE) &&
174 (atomic_read(v: &inode->i_writecount) == 1) &&
175 !EXT4_I(inode)->i_reserved_data_blocks) {
176 down_write(sem: &EXT4_I(inode)->i_data_sem);
177 ext4_discard_preallocations(inode);
178 up_write(sem: &EXT4_I(inode)->i_data_sem);
179 }
180 if (is_dx(inode) && filp->private_data)
181 ext4_htree_free_dir_info(p: filp->private_data);
182
183 return 0;
184}
185
186/*
187 * This tests whether the IO in question is block-aligned or not.
188 * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
189 * are converted to written only after the IO is complete. Until they are
190 * mapped, these blocks appear as holes, so dio_zero_block() will assume that
191 * it needs to zero out portions of the start and/or end block. If 2 AIO
192 * threads are at work on the same unwritten block, they must be synchronized
193 * or one thread will zero the other's data, causing corruption.
194 */
195static bool
196ext4_unaligned_io(struct inode *inode, struct iov_iter *from, loff_t pos)
197{
198 struct super_block *sb = inode->i_sb;
199 unsigned long blockmask = sb->s_blocksize - 1;
200
201 if ((pos | iov_iter_alignment(i: from)) & blockmask)
202 return true;
203
204 return false;
205}
206
207static bool
208ext4_extending_io(struct inode *inode, loff_t offset, size_t len)
209{
210 if (offset + len > i_size_read(inode) ||
211 offset + len > EXT4_I(inode)->i_disksize)
212 return true;
213 return false;
214}
215
216/* Is IO overwriting allocated or initialized blocks? */
217static bool ext4_overwrite_io(struct inode *inode,
218 loff_t pos, loff_t len, bool *unwritten)
219{
220 struct ext4_map_blocks map;
221 unsigned int blkbits = inode->i_blkbits;
222 int err, blklen;
223
224 if (pos + len > i_size_read(inode))
225 return false;
226
227 map.m_lblk = pos >> blkbits;
228 map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
229 blklen = map.m_len;
230
231 err = ext4_map_blocks(NULL, inode, map: &map, flags: 0);
232 if (err != blklen)
233 return false;
234 /*
235 * 'err==len' means that all of the blocks have been preallocated,
236 * regardless of whether they have been initialized or not. We need to
237 * check m_flags to distinguish the unwritten extents.
238 */
239 *unwritten = !(map.m_flags & EXT4_MAP_MAPPED);
240 return true;
241}
242
243static ssize_t ext4_generic_write_checks(struct kiocb *iocb,
244 struct iov_iter *from)
245{
246 struct inode *inode = file_inode(f: iocb->ki_filp);
247 ssize_t ret;
248
249 if (unlikely(IS_IMMUTABLE(inode)))
250 return -EPERM;
251
252 ret = generic_write_checks(iocb, from);
253 if (ret <= 0)
254 return ret;
255
256 /*
257 * If we have encountered a bitmap-format file, the size limit
258 * is smaller than s_maxbytes, which is for extent-mapped files.
259 */
260 if (!(ext4_test_inode_flag(inode, bit: EXT4_INODE_EXTENTS))) {
261 struct ext4_sb_info *sbi = EXT4_SB(sb: inode->i_sb);
262
263 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
264 return -EFBIG;
265 iov_iter_truncate(i: from, count: sbi->s_bitmap_maxbytes - iocb->ki_pos);
266 }
267
268 return iov_iter_count(i: from);
269}
270
271static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
272{
273 ssize_t ret, count;
274
275 count = ext4_generic_write_checks(iocb, from);
276 if (count <= 0)
277 return count;
278
279 ret = file_modified(file: iocb->ki_filp);
280 if (ret)
281 return ret;
282 return count;
283}
284
285static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
286 struct iov_iter *from)
287{
288 ssize_t ret;
289 struct inode *inode = file_inode(f: iocb->ki_filp);
290
291 if (iocb->ki_flags & IOCB_NOWAIT)
292 return -EOPNOTSUPP;
293
294 inode_lock(inode);
295 ret = ext4_write_checks(iocb, from);
296 if (ret <= 0)
297 goto out;
298
299 ret = generic_perform_write(iocb, from);
300
301out:
302 inode_unlock(inode);
303 if (unlikely(ret <= 0))
304 return ret;
305 return generic_write_sync(iocb, count: ret);
306}
307
308static ssize_t ext4_handle_inode_extension(struct inode *inode, loff_t offset,
309 ssize_t written, ssize_t count)
310{
311 handle_t *handle;
312
313 lockdep_assert_held_write(&inode->i_rwsem);
314 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
315 if (IS_ERR(ptr: handle))
316 return PTR_ERR(ptr: handle);
317
318 if (ext4_update_inode_size(inode, newsize: offset + written)) {
319 int ret = ext4_mark_inode_dirty(handle, inode);
320 if (unlikely(ret)) {
321 ext4_journal_stop(handle);
322 return ret;
323 }
324 }
325
326 if ((written == count) && inode->i_nlink)
327 ext4_orphan_del(handle, inode);
328 ext4_journal_stop(handle);
329
330 return written;
331}
332
333/*
334 * Clean up the inode after DIO or DAX extending write has completed and the
335 * inode size has been updated using ext4_handle_inode_extension().
336 */
337static void ext4_inode_extension_cleanup(struct inode *inode, bool need_trunc)
338{
339 lockdep_assert_held_write(&inode->i_rwsem);
340 if (need_trunc) {
341 ext4_truncate_failed_write(inode);
342 /*
343 * If the truncate operation failed early, then the inode may
344 * still be on the orphan list. In that case, we need to try
345 * remove the inode from the in-memory linked list.
346 */
347 if (inode->i_nlink)
348 ext4_orphan_del(NULL, inode);
349 return;
350 }
351 /*
352 * If i_disksize got extended either due to writeback of delalloc
353 * blocks or extending truncate while the DIO was running we could fail
354 * to cleanup the orphan list in ext4_handle_inode_extension(). Do it
355 * now.
356 */
357 if (!list_empty(head: &EXT4_I(inode)->i_orphan) && inode->i_nlink) {
358 handle_t *handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
359
360 if (IS_ERR(ptr: handle)) {
361 /*
362 * The write has successfully completed. Not much to
363 * do with the error here so just cleanup the orphan
364 * list and hope for the best.
365 */
366 ext4_orphan_del(NULL, inode);
367 return;
368 }
369 ext4_orphan_del(handle, inode);
370 ext4_journal_stop(handle);
371 }
372}
373
374static int ext4_dio_write_end_io(struct kiocb *iocb, ssize_t size,
375 int error, unsigned int flags)
376{
377 loff_t pos = iocb->ki_pos;
378 struct inode *inode = file_inode(f: iocb->ki_filp);
379
380
381 if (!error && size && (flags & IOMAP_DIO_UNWRITTEN) &&
382 (iocb->ki_flags & IOCB_ATOMIC))
383 error = ext4_convert_unwritten_extents_atomic(NULL, inode, offset: pos,
384 len: size);
385 else if (!error && size && flags & IOMAP_DIO_UNWRITTEN)
386 error = ext4_convert_unwritten_extents(NULL, inode, offset: pos, len: size);
387 if (error)
388 return error;
389 /*
390 * Note that EXT4_I(inode)->i_disksize can get extended up to
391 * inode->i_size while the I/O was running due to writeback of delalloc
392 * blocks. But the code in ext4_iomap_alloc() is careful to use
393 * zeroed/unwritten extents if this is possible; thus we won't leave
394 * uninitialized blocks in a file even if we didn't succeed in writing
395 * as much as we intended. Also we can race with truncate or write
396 * expanding the file so we have to be a bit careful here.
397 */
398 if (pos + size <= READ_ONCE(EXT4_I(inode)->i_disksize) &&
399 pos + size <= i_size_read(inode))
400 return 0;
401 error = ext4_handle_inode_extension(inode, offset: pos, written: size, count: size);
402 return error < 0 ? error : 0;
403}
404
405static const struct iomap_dio_ops ext4_dio_write_ops = {
406 .end_io = ext4_dio_write_end_io,
407};
408
409/*
410 * The intention here is to start with shared lock acquired then see if any
411 * condition requires an exclusive inode lock. If yes, then we restart the
412 * whole operation by releasing the shared lock and acquiring exclusive lock.
413 *
414 * - For unaligned_io we never take shared lock as it may cause data corruption
415 * when two unaligned IO tries to modify the same block e.g. while zeroing.
416 *
417 * - For extending writes case we don't take the shared lock, since it requires
418 * updating inode i_disksize and/or orphan handling with exclusive lock.
419 *
420 * - shared locking will only be true mostly with overwrites, including
421 * initialized blocks and unwritten blocks. For overwrite unwritten blocks
422 * we protect splitting extents by i_data_sem in ext4_inode_info, so we can
423 * also release exclusive i_rwsem lock.
424 *
425 * - Otherwise we will switch to exclusive i_rwsem lock.
426 */
427static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from,
428 bool *ilock_shared, bool *extend,
429 bool *unwritten, int *dio_flags)
430{
431 struct file *file = iocb->ki_filp;
432 struct inode *inode = file_inode(f: file);
433 loff_t offset;
434 size_t count;
435 ssize_t ret;
436 bool overwrite, unaligned_io;
437
438restart:
439 ret = ext4_generic_write_checks(iocb, from);
440 if (ret <= 0)
441 goto out;
442
443 offset = iocb->ki_pos;
444 count = ret;
445
446 unaligned_io = ext4_unaligned_io(inode, from, pos: offset);
447 *extend = ext4_extending_io(inode, offset, len: count);
448 overwrite = ext4_overwrite_io(inode, pos: offset, len: count, unwritten);
449
450 /*
451 * Determine whether we need to upgrade to an exclusive lock. This is
452 * required to change security info in file_modified(), for extending
453 * I/O, any form of non-overwrite I/O, and unaligned I/O to unwritten
454 * extents (as partial block zeroing may be required).
455 *
456 * Note that unaligned writes are allowed under shared lock so long as
457 * they are pure overwrites. Otherwise, concurrent unaligned writes risk
458 * data corruption due to partial block zeroing in the dio layer, and so
459 * the I/O must occur exclusively.
460 */
461 if (*ilock_shared &&
462 ((!IS_NOSEC(inode) || *extend || !overwrite ||
463 (unaligned_io && *unwritten)))) {
464 if (iocb->ki_flags & IOCB_NOWAIT) {
465 ret = -EAGAIN;
466 goto out;
467 }
468 inode_unlock_shared(inode);
469 *ilock_shared = false;
470 inode_lock(inode);
471 goto restart;
472 }
473
474 /*
475 * Now that locking is settled, determine dio flags and exclusivity
476 * requirements. We don't use DIO_OVERWRITE_ONLY because we enforce
477 * behavior already. The inode lock is already held exclusive if the
478 * write is non-overwrite or extending, so drain all outstanding dio and
479 * set the force wait dio flag.
480 */
481 if (!*ilock_shared && (unaligned_io || *extend)) {
482 if (iocb->ki_flags & IOCB_NOWAIT) {
483 ret = -EAGAIN;
484 goto out;
485 }
486 if (unaligned_io && (!overwrite || *unwritten))
487 inode_dio_wait(inode);
488 *dio_flags = IOMAP_DIO_FORCE_WAIT;
489 }
490
491 ret = file_modified(file);
492 if (ret < 0)
493 goto out;
494
495 return count;
496out:
497 if (*ilock_shared)
498 inode_unlock_shared(inode);
499 else
500 inode_unlock(inode);
501 return ret;
502}
503
504static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
505{
506 ssize_t ret;
507 handle_t *handle;
508 struct inode *inode = file_inode(f: iocb->ki_filp);
509 loff_t offset = iocb->ki_pos;
510 size_t count = iov_iter_count(i: from);
511 const struct iomap_ops *iomap_ops = &ext4_iomap_ops;
512 bool extend = false, unwritten = false;
513 bool ilock_shared = true;
514 int dio_flags = 0;
515
516 /*
517 * Quick check here without any i_rwsem lock to see if it is extending
518 * IO. A more reliable check is done in ext4_dio_write_checks() with
519 * proper locking in place.
520 */
521 if (offset + count > i_size_read(inode))
522 ilock_shared = false;
523
524 if (iocb->ki_flags & IOCB_NOWAIT) {
525 if (ilock_shared) {
526 if (!inode_trylock_shared(inode))
527 return -EAGAIN;
528 } else {
529 if (!inode_trylock(inode))
530 return -EAGAIN;
531 }
532 } else {
533 if (ilock_shared)
534 inode_lock_shared(inode);
535 else
536 inode_lock(inode);
537 }
538
539 /* Fallback to buffered I/O if the inode does not support direct I/O. */
540 if (!ext4_should_use_dio(iocb, iter: from)) {
541 if (ilock_shared)
542 inode_unlock_shared(inode);
543 else
544 inode_unlock(inode);
545 return ext4_buffered_write_iter(iocb, from);
546 }
547
548 /*
549 * Prevent inline data from being created since we are going to allocate
550 * blocks for DIO. We know the inode does not currently have inline data
551 * because ext4_should_use_dio() checked for it, but we have to clear
552 * the state flag before the write checks because a lock cycle could
553 * introduce races with other writers.
554 */
555 ext4_clear_inode_state(inode, bit: EXT4_STATE_MAY_INLINE_DATA);
556
557 ret = ext4_dio_write_checks(iocb, from, ilock_shared: &ilock_shared, extend: &extend,
558 unwritten: &unwritten, dio_flags: &dio_flags);
559 if (ret <= 0)
560 return ret;
561
562 offset = iocb->ki_pos;
563 count = ret;
564
565 if (extend) {
566 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
567 if (IS_ERR(ptr: handle)) {
568 ret = PTR_ERR(ptr: handle);
569 goto out;
570 }
571
572 ret = ext4_orphan_add(handle, inode);
573 ext4_journal_stop(handle);
574 if (ret)
575 goto out;
576 }
577
578 if (ilock_shared && !unwritten)
579 iomap_ops = &ext4_iomap_overwrite_ops;
580 ret = iomap_dio_rw(iocb, iter: from, ops: iomap_ops, dops: &ext4_dio_write_ops,
581 dio_flags, NULL, done_before: 0);
582 if (ret == -ENOTBLK)
583 ret = 0;
584 if (extend) {
585 /*
586 * We always perform extending DIO write synchronously so by
587 * now the IO is completed and ext4_handle_inode_extension()
588 * was called. Cleanup the inode in case of error or race with
589 * writeback of delalloc blocks.
590 */
591 WARN_ON_ONCE(ret == -EIOCBQUEUED);
592 ext4_inode_extension_cleanup(inode, need_trunc: ret < 0);
593 }
594
595out:
596 if (ilock_shared)
597 inode_unlock_shared(inode);
598 else
599 inode_unlock(inode);
600
601 if (ret >= 0 && iov_iter_count(i: from)) {
602 ssize_t err;
603 loff_t endbyte;
604
605 /*
606 * There is no support for atomic writes on buffered-io yet,
607 * we should never fallback to buffered-io for DIO atomic
608 * writes.
609 */
610 WARN_ON_ONCE(iocb->ki_flags & IOCB_ATOMIC);
611
612 offset = iocb->ki_pos;
613 err = ext4_buffered_write_iter(iocb, from);
614 if (err < 0)
615 return err;
616
617 /*
618 * We need to ensure that the pages within the page cache for
619 * the range covered by this I/O are written to disk and
620 * invalidated. This is in attempt to preserve the expected
621 * direct I/O semantics in the case we fallback to buffered I/O
622 * to complete off the I/O request.
623 */
624 ret += err;
625 endbyte = offset + err - 1;
626 err = filemap_write_and_wait_range(mapping: iocb->ki_filp->f_mapping,
627 lstart: offset, lend: endbyte);
628 if (!err)
629 invalidate_mapping_pages(mapping: iocb->ki_filp->f_mapping,
630 start: offset >> PAGE_SHIFT,
631 end: endbyte >> PAGE_SHIFT);
632 }
633
634 return ret;
635}
636
637#ifdef CONFIG_FS_DAX
638static ssize_t
639ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
640{
641 ssize_t ret;
642 size_t count;
643 loff_t offset;
644 handle_t *handle;
645 bool extend = false;
646 struct inode *inode = file_inode(f: iocb->ki_filp);
647
648 if (iocb->ki_flags & IOCB_NOWAIT) {
649 if (!inode_trylock(inode))
650 return -EAGAIN;
651 } else {
652 inode_lock(inode);
653 }
654
655 ret = ext4_write_checks(iocb, from);
656 if (ret <= 0)
657 goto out;
658
659 offset = iocb->ki_pos;
660 count = iov_iter_count(i: from);
661
662 if (offset + count > EXT4_I(inode)->i_disksize) {
663 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
664 if (IS_ERR(ptr: handle)) {
665 ret = PTR_ERR(ptr: handle);
666 goto out;
667 }
668
669 ret = ext4_orphan_add(handle, inode);
670 if (ret) {
671 ext4_journal_stop(handle);
672 goto out;
673 }
674
675 extend = true;
676 ext4_journal_stop(handle);
677 }
678
679 ret = dax_iomap_rw(iocb, iter: from, ops: &ext4_iomap_ops);
680
681 if (extend) {
682 ret = ext4_handle_inode_extension(inode, offset, written: ret, count);
683 ext4_inode_extension_cleanup(inode, need_trunc: ret < (ssize_t)count);
684 }
685out:
686 inode_unlock(inode);
687 if (ret > 0)
688 ret = generic_write_sync(iocb, count: ret);
689 return ret;
690}
691#endif
692
693static ssize_t
694ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
695{
696 int ret;
697 struct inode *inode = file_inode(f: iocb->ki_filp);
698
699 ret = ext4_emergency_state(sb: inode->i_sb);
700 if (unlikely(ret))
701 return ret;
702
703#ifdef CONFIG_FS_DAX
704 if (IS_DAX(inode))
705 return ext4_dax_write_iter(iocb, from);
706#endif
707
708 if (iocb->ki_flags & IOCB_ATOMIC) {
709 size_t len = iov_iter_count(i: from);
710
711 if (len < EXT4_SB(sb: inode->i_sb)->s_awu_min ||
712 len > EXT4_SB(sb: inode->i_sb)->s_awu_max)
713 return -EINVAL;
714
715 ret = generic_atomic_write_valid(iocb, iter: from);
716 if (ret)
717 return ret;
718 }
719
720 if (iocb->ki_flags & IOCB_DIRECT)
721 return ext4_dio_write_iter(iocb, from);
722 else
723 return ext4_buffered_write_iter(iocb, from);
724}
725
726#ifdef CONFIG_FS_DAX
727static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf, unsigned int order)
728{
729 int error = 0;
730 vm_fault_t result;
731 int retries = 0;
732 handle_t *handle = NULL;
733 struct inode *inode = file_inode(f: vmf->vma->vm_file);
734 struct super_block *sb = inode->i_sb;
735
736 /*
737 * We have to distinguish real writes from writes which will result in a
738 * COW page; COW writes should *not* poke the journal (the file will not
739 * be changed). Doing so would cause unintended failures when mounted
740 * read-only.
741 *
742 * We check for VM_SHARED rather than vmf->cow_page since the latter is
743 * unset for order != 0 (i.e. only in do_cow_fault); for
744 * other sizes, dax_iomap_fault will handle splitting / fallback so that
745 * we eventually come back with a COW page.
746 */
747 bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
748 (vmf->vma->vm_flags & VM_SHARED);
749 struct address_space *mapping = vmf->vma->vm_file->f_mapping;
750 pfn_t pfn;
751
752 if (write) {
753 sb_start_pagefault(sb);
754 file_update_time(file: vmf->vma->vm_file);
755 filemap_invalidate_lock_shared(mapping);
756retry:
757 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
758 EXT4_DATA_TRANS_BLOCKS(sb));
759 if (IS_ERR(ptr: handle)) {
760 filemap_invalidate_unlock_shared(mapping);
761 sb_end_pagefault(sb);
762 return VM_FAULT_SIGBUS;
763 }
764 } else {
765 filemap_invalidate_lock_shared(mapping);
766 }
767 result = dax_iomap_fault(vmf, order, pfnp: &pfn, errp: &error, ops: &ext4_iomap_ops);
768 if (write) {
769 ext4_journal_stop(handle);
770
771 if ((result & VM_FAULT_ERROR) && error == -ENOSPC &&
772 ext4_should_retry_alloc(sb, retries: &retries))
773 goto retry;
774 /* Handling synchronous page fault? */
775 if (result & VM_FAULT_NEEDDSYNC)
776 result = dax_finish_sync_fault(vmf, order, pfn);
777 filemap_invalidate_unlock_shared(mapping);
778 sb_end_pagefault(sb);
779 } else {
780 filemap_invalidate_unlock_shared(mapping);
781 }
782
783 return result;
784}
785
786static vm_fault_t ext4_dax_fault(struct vm_fault *vmf)
787{
788 return ext4_dax_huge_fault(vmf, order: 0);
789}
790
791static const struct vm_operations_struct ext4_dax_vm_ops = {
792 .fault = ext4_dax_fault,
793 .huge_fault = ext4_dax_huge_fault,
794 .page_mkwrite = ext4_dax_fault,
795 .pfn_mkwrite = ext4_dax_fault,
796};
797#else
798#define ext4_dax_vm_ops ext4_file_vm_ops
799#endif
800
801static const struct vm_operations_struct ext4_file_vm_ops = {
802 .fault = filemap_fault,
803 .map_pages = filemap_map_pages,
804 .page_mkwrite = ext4_page_mkwrite,
805};
806
807static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
808{
809 int ret;
810 struct inode *inode = file->f_mapping->host;
811 struct dax_device *dax_dev = EXT4_SB(sb: inode->i_sb)->s_daxdev;
812
813 if (file->f_mode & FMODE_WRITE)
814 ret = ext4_emergency_state(sb: inode->i_sb);
815 else
816 ret = ext4_forced_shutdown(sb: inode->i_sb) ? -EIO : 0;
817 if (unlikely(ret))
818 return ret;
819
820 /*
821 * We don't support synchronous mappings for non-DAX files and
822 * for DAX files if underneath dax_device is not synchronous.
823 */
824 if (!daxdev_mapping_supported(vma, dax_dev))
825 return -EOPNOTSUPP;
826
827 file_accessed(file);
828 if (IS_DAX(file_inode(file))) {
829 vma->vm_ops = &ext4_dax_vm_ops;
830 vm_flags_set(vma, VM_HUGEPAGE);
831 } else {
832 vma->vm_ops = &ext4_file_vm_ops;
833 }
834 return 0;
835}
836
837static int ext4_sample_last_mounted(struct super_block *sb,
838 struct vfsmount *mnt)
839{
840 struct ext4_sb_info *sbi = EXT4_SB(sb);
841 struct path path;
842 char buf[64], *cp;
843 handle_t *handle;
844 int err;
845
846 if (likely(ext4_test_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED)))
847 return 0;
848
849 if (ext4_emergency_state(sb) || sb_rdonly(sb) ||
850 !sb_start_intwrite_trylock(sb))
851 return 0;
852
853 ext4_set_mount_flag(sb, bit: EXT4_MF_MNTDIR_SAMPLED);
854 /*
855 * Sample where the filesystem has been mounted and
856 * store it in the superblock for sysadmin convenience
857 * when trying to sort through large numbers of block
858 * devices or filesystem images.
859 */
860 memset(buf, 0, sizeof(buf));
861 path.mnt = mnt;
862 path.dentry = mnt->mnt_root;
863 cp = d_path(&path, buf, sizeof(buf));
864 err = 0;
865 if (IS_ERR(ptr: cp))
866 goto out;
867
868 handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
869 err = PTR_ERR(ptr: handle);
870 if (IS_ERR(ptr: handle))
871 goto out;
872 BUFFER_TRACE(sbi->s_sbh, "get_write_access");
873 err = ext4_journal_get_write_access(handle, sb, sbi->s_sbh,
874 EXT4_JTR_NONE);
875 if (err)
876 goto out_journal;
877 lock_buffer(bh: sbi->s_sbh);
878 strtomem_pad(sbi->s_es->s_last_mounted, cp, 0);
879 ext4_superblock_csum_set(sb);
880 unlock_buffer(bh: sbi->s_sbh);
881 ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
882out_journal:
883 ext4_journal_stop(handle);
884out:
885 sb_end_intwrite(sb);
886 return err;
887}
888
889static int ext4_file_open(struct inode *inode, struct file *filp)
890{
891 int ret;
892
893 if (filp->f_mode & FMODE_WRITE)
894 ret = ext4_emergency_state(sb: inode->i_sb);
895 else
896 ret = ext4_forced_shutdown(sb: inode->i_sb) ? -EIO : 0;
897 if (unlikely(ret))
898 return ret;
899
900 ret = ext4_sample_last_mounted(sb: inode->i_sb, mnt: filp->f_path.mnt);
901 if (ret)
902 return ret;
903
904 ret = fscrypt_file_open(inode, filp);
905 if (ret)
906 return ret;
907
908 ret = fsverity_file_open(inode, filp);
909 if (ret)
910 return ret;
911
912 /*
913 * Set up the jbd2_inode if we are opening the inode for
914 * writing and the journal is present
915 */
916 if (filp->f_mode & FMODE_WRITE) {
917 ret = ext4_inode_attach_jinode(inode);
918 if (ret < 0)
919 return ret;
920 }
921
922 if (ext4_inode_can_atomic_write(inode))
923 filp->f_mode |= FMODE_CAN_ATOMIC_WRITE;
924
925 filp->f_mode |= FMODE_NOWAIT | FMODE_CAN_ODIRECT;
926 return dquot_file_open(inode, file: filp);
927}
928
929/*
930 * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
931 * by calling generic_file_llseek_size() with the appropriate maxbytes
932 * value for each.
933 */
934loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
935{
936 struct inode *inode = file->f_mapping->host;
937 loff_t maxbytes = ext4_get_maxbytes(inode);
938
939 switch (whence) {
940 default:
941 return generic_file_llseek_size(file, offset, whence,
942 maxsize: maxbytes, eof: i_size_read(inode));
943 case SEEK_HOLE:
944 inode_lock_shared(inode);
945 offset = iomap_seek_hole(inode, offset,
946 ops: &ext4_iomap_report_ops);
947 inode_unlock_shared(inode);
948 break;
949 case SEEK_DATA:
950 inode_lock_shared(inode);
951 offset = iomap_seek_data(inode, offset,
952 ops: &ext4_iomap_report_ops);
953 inode_unlock_shared(inode);
954 break;
955 }
956
957 if (offset < 0)
958 return offset;
959 return vfs_setpos(file, offset, maxsize: maxbytes);
960}
961
962const struct file_operations ext4_file_operations = {
963 .llseek = ext4_llseek,
964 .read_iter = ext4_file_read_iter,
965 .write_iter = ext4_file_write_iter,
966 .iopoll = iocb_bio_iopoll,
967 .unlocked_ioctl = ext4_ioctl,
968#ifdef CONFIG_COMPAT
969 .compat_ioctl = ext4_compat_ioctl,
970#endif
971 .mmap = ext4_file_mmap,
972 .open = ext4_file_open,
973 .release = ext4_release_file,
974 .fsync = ext4_sync_file,
975 .get_unmapped_area = thp_get_unmapped_area,
976 .splice_read = ext4_file_splice_read,
977 .splice_write = iter_file_splice_write,
978 .fallocate = ext4_fallocate,
979 .fop_flags = FOP_MMAP_SYNC | FOP_BUFFER_RASYNC |
980 FOP_DIO_PARALLEL_WRITE,
981};
982
983const struct inode_operations ext4_file_inode_operations = {
984 .setattr = ext4_setattr,
985 .getattr = ext4_file_getattr,
986 .listxattr = ext4_listxattr,
987 .get_inode_acl = ext4_get_acl,
988 .set_acl = ext4_set_acl,
989 .fiemap = ext4_fiemap,
990 .fileattr_get = ext4_fileattr_get,
991 .fileattr_set = ext4_fileattr_set,
992};
993
994

source code of linux/fs/ext4/file.c