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 */
55 static bool ext4_should_use_dio(struct kiocb *iocb, struct iov_iter *iter)
56 {
57 struct inode *inode = file_inode(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
69 static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
70 {
71 ssize_t ret;
72 struct inode *inode = file_inode(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, 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, to, &ext4_iomap_ops, NULL, 0, NULL, 0);
95 inode_unlock_shared(inode);
96
97 file_accessed(iocb->ki_filp);
98 return ret;
99 }
100
101 #ifdef CONFIG_FS_DAX
102 static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
103 {
104 struct inode *inode = file_inode(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, to, &ext4_iomap_ops);
123 inode_unlock_shared(inode);
124
125 file_accessed(iocb->ki_filp);
126 return ret;
127 }
128 #endif
129
130 static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
131 {
132 struct inode *inode = file_inode(iocb->ki_filp);
133
134 if (unlikely(ext4_forced_shutdown(inode->i_sb)))
135 return -EIO;
136
137 if (!iov_iter_count(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
150 static 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(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 */
166 static int ext4_release_file(struct inode *inode, struct file *filp)
167 {
168 if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
169 ext4_alloc_da_blocks(inode);
170 ext4_clear_inode_state(inode, 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(&inode->i_writecount) == 1) &&
175 !EXT4_I(inode)->i_reserved_data_blocks) {
176 down_write(&EXT4_I(inode)->i_data_sem);
177 ext4_discard_preallocations(inode);
178 up_write(&EXT4_I(inode)->i_data_sem);
179 }
180 if (is_dx(inode) && filp->private_data)
181 ext4_htree_free_dir_info(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 */
195 static bool
196 ext4_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(from)) & blockmask)
202 return true;
203
204 return false;
205 }
206
207 static bool
208 ext4_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? */
217 static 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, 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
243 static ssize_t ext4_generic_write_checks(struct kiocb *iocb,
244 struct iov_iter *from)
245 {
246 struct inode *inode = file_inode(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, EXT4_INODE_EXTENTS))) {
261 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
262
263 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
264 return -EFBIG;
265 iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
266 }
267
268 return iov_iter_count(from);
269 }
270
271 static 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(iocb->ki_filp);
280 if (ret)
281 return ret;
282 return count;
283 }
284
285 static 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(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
301 out:
302 inode_unlock(inode);
303 if (unlikely(ret <= 0))
304 return ret;
305 return generic_write_sync(iocb, ret);
306 }
307
308 static ssize_t ext4_handle_inode_extension(struct inode *inode, loff_t offset,
309 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(handle))
316 return PTR_ERR(handle);
317
318 if (ext4_update_inode_size(inode, offset + count)) {
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 (inode->i_nlink)
327 ext4_orphan_del(handle, inode);
328 ext4_journal_stop(handle);
329
330 return count;
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 */
337 static void ext4_inode_extension_cleanup(struct inode *inode, ssize_t count)
338 {
339 lockdep_assert_held_write(&inode->i_rwsem);
340 if (count < 0) {
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(&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(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
374 static 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(iocb->ki_filp);
379
380 if (!error && size && flags & IOMAP_DIO_UNWRITTEN)
381 error = ext4_convert_unwritten_extents(NULL, inode, pos, size);
382 if (error)
383 return error;
384 /*
385 * Note that EXT4_I(inode)->i_disksize can get extended up to
386 * inode->i_size while the I/O was running due to writeback of delalloc
387 * blocks. But the code in ext4_iomap_alloc() is careful to use
388 * zeroed/unwritten extents if this is possible; thus we won't leave
389 * uninitialized blocks in a file even if we didn't succeed in writing
390 * as much as we intended. Also we can race with truncate or write
391 * expanding the file so we have to be a bit careful here.
392 */
393 if (pos + size <= READ_ONCE(EXT4_I(inode)->i_disksize) &&
394 pos + size <= i_size_read(inode))
395 return size;
396 return ext4_handle_inode_extension(inode, pos, size);
397 }
398
399 static const struct iomap_dio_ops ext4_dio_write_ops = {
400 .end_io = ext4_dio_write_end_io,
401 };
402
403 /*
404 * The intention here is to start with shared lock acquired then see if any
405 * condition requires an exclusive inode lock. If yes, then we restart the
406 * whole operation by releasing the shared lock and acquiring exclusive lock.
407 *
408 * - For unaligned_io we never take shared lock as it may cause data corruption
409 * when two unaligned IO tries to modify the same block e.g. while zeroing.
410 *
411 * - For extending writes case we don't take the shared lock, since it requires
412 * updating inode i_disksize and/or orphan handling with exclusive lock.
413 *
414 * - shared locking will only be true mostly with overwrites, including
415 * initialized blocks and unwritten blocks. For overwrite unwritten blocks
416 * we protect splitting extents by i_data_sem in ext4_inode_info, so we can
417 * also release exclusive i_rwsem lock.
418 *
419 * - Otherwise we will switch to exclusive i_rwsem lock.
420 */
421 static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from,
422 bool *ilock_shared, bool *extend,
423 bool *unwritten, int *dio_flags)
424 {
425 struct file *file = iocb->ki_filp;
426 struct inode *inode = file_inode(file);
427 loff_t offset;
428 size_t count;
429 ssize_t ret;
430 bool overwrite, unaligned_io;
431
432 restart:
433 ret = ext4_generic_write_checks(iocb, from);
434 if (ret <= 0)
435 goto out;
436
437 offset = iocb->ki_pos;
438 count = ret;
439
440 unaligned_io = ext4_unaligned_io(inode, from, offset);
441 *extend = ext4_extending_io(inode, offset, count);
442 overwrite = ext4_overwrite_io(inode, offset, count, unwritten);
443
444 /*
445 * Determine whether we need to upgrade to an exclusive lock. This is
446 * required to change security info in file_modified(), for extending
447 * I/O, any form of non-overwrite I/O, and unaligned I/O to unwritten
448 * extents (as partial block zeroing may be required).
449 *
450 * Note that unaligned writes are allowed under shared lock so long as
451 * they are pure overwrites. Otherwise, concurrent unaligned writes risk
452 * data corruption due to partial block zeroing in the dio layer, and so
453 * the I/O must occur exclusively.
454 */
455 if (*ilock_shared &&
456 ((!IS_NOSEC(inode) || *extend || !overwrite ||
457 (unaligned_io && *unwritten)))) {
458 if (iocb->ki_flags & IOCB_NOWAIT) {
459 ret = -EAGAIN;
460 goto out;
461 }
462 inode_unlock_shared(inode);
463 *ilock_shared = false;
464 inode_lock(inode);
465 goto restart;
466 }
467
468 /*
469 * Now that locking is settled, determine dio flags and exclusivity
470 * requirements. We don't use DIO_OVERWRITE_ONLY because we enforce
471 * behavior already. The inode lock is already held exclusive if the
472 * write is non-overwrite or extending, so drain all outstanding dio and
473 * set the force wait dio flag.
474 */
475 if (!*ilock_shared && (unaligned_io || *extend)) {
476 if (iocb->ki_flags & IOCB_NOWAIT) {
477 ret = -EAGAIN;
478 goto out;
479 }
480 if (unaligned_io && (!overwrite || *unwritten))
481 inode_dio_wait(inode);
482 *dio_flags = IOMAP_DIO_FORCE_WAIT;
483 }
484
485 ret = file_modified(file);
486 if (ret < 0)
487 goto out;
488
489 return count;
490 out:
491 if (*ilock_shared)
492 inode_unlock_shared(inode);
493 else
494 inode_unlock(inode);
495 return ret;
496 }
497
498 static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
499 {
500 ssize_t ret;
501 handle_t *handle;
502 struct inode *inode = file_inode(iocb->ki_filp);
503 loff_t offset = iocb->ki_pos;
504 size_t count = iov_iter_count(from);
505 const struct iomap_ops *iomap_ops = &ext4_iomap_ops;
506 bool extend = false, unwritten = false;
507 bool ilock_shared = true;
508 int dio_flags = 0;
509
510 /*
511 * Quick check here without any i_rwsem lock to see if it is extending
512 * IO. A more reliable check is done in ext4_dio_write_checks() with
513 * proper locking in place.
514 */
515 if (offset + count > i_size_read(inode))
516 ilock_shared = false;
517
518 if (iocb->ki_flags & IOCB_NOWAIT) {
519 if (ilock_shared) {
520 if (!inode_trylock_shared(inode))
521 return -EAGAIN;
522 } else {
523 if (!inode_trylock(inode))
524 return -EAGAIN;
525 }
526 } else {
527 if (ilock_shared)
528 inode_lock_shared(inode);
529 else
530 inode_lock(inode);
531 }
532
533 /* Fallback to buffered I/O if the inode does not support direct I/O. */
534 if (!ext4_should_use_dio(iocb, from)) {
535 if (ilock_shared)
536 inode_unlock_shared(inode);
537 else
538 inode_unlock(inode);
539 return ext4_buffered_write_iter(iocb, from);
540 }
541
542 /*
543 * Prevent inline data from being created since we are going to allocate
544 * blocks for DIO. We know the inode does not currently have inline data
545 * because ext4_should_use_dio() checked for it, but we have to clear
546 * the state flag before the write checks because a lock cycle could
547 * introduce races with other writers.
548 */
549 ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
550
551 ret = ext4_dio_write_checks(iocb, from, &ilock_shared, &extend,
552 &unwritten, &dio_flags);
553 if (ret <= 0)
554 return ret;
555
556 offset = iocb->ki_pos;
557 count = ret;
558
559 if (extend) {
560 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
561 if (IS_ERR(handle)) {
562 ret = PTR_ERR(handle);
563 goto out;
564 }
565
566 ret = ext4_orphan_add(handle, inode);
567 if (ret) {
568 ext4_journal_stop(handle);
569 goto out;
570 }
571
572 ext4_journal_stop(handle);
573 }
574
575 if (ilock_shared && !unwritten)
576 iomap_ops = &ext4_iomap_overwrite_ops;
577 ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops,
578 dio_flags, NULL, 0);
579 if (ret == -ENOTBLK)
580 ret = 0;
581 if (extend) {
582 /*
583 * We always perform extending DIO write synchronously so by
584 * now the IO is completed and ext4_handle_inode_extension()
585 * was called. Cleanup the inode in case of error or race with
586 * writeback of delalloc blocks.
587 */
588 WARN_ON_ONCE(ret == -EIOCBQUEUED);
589 ext4_inode_extension_cleanup(inode, ret);
590 }
591
592 out:
593 if (ilock_shared)
594 inode_unlock_shared(inode);
595 else
596 inode_unlock(inode);
597
598 if (ret >= 0 && iov_iter_count(from)) {
599 ssize_t err;
600 loff_t endbyte;
601
602 offset = iocb->ki_pos;
603 err = ext4_buffered_write_iter(iocb, from);
604 if (err < 0)
605 return err;
606
607 /*
608 * We need to ensure that the pages within the page cache for
609 * the range covered by this I/O are written to disk and
610 * invalidated. This is in attempt to preserve the expected
611 * direct I/O semantics in the case we fallback to buffered I/O
612 * to complete off the I/O request.
613 */
614 ret += err;
615 endbyte = offset + err - 1;
616 err = filemap_write_and_wait_range(iocb->ki_filp->f_mapping,
617 offset, endbyte);
618 if (!err)
619 invalidate_mapping_pages(iocb->ki_filp->f_mapping,
620 offset >> PAGE_SHIFT,
621 endbyte >> PAGE_SHIFT);
622 }
623
624 return ret;
625 }
626
627 #ifdef CONFIG_FS_DAX
628 static ssize_t
629 ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
630 {
631 ssize_t ret;
632 size_t count;
633 loff_t offset;
634 handle_t *handle;
635 bool extend = false;
636 struct inode *inode = file_inode(iocb->ki_filp);
637
638 if (iocb->ki_flags & IOCB_NOWAIT) {
639 if (!inode_trylock(inode))
640 return -EAGAIN;
641 } else {
642 inode_lock(inode);
643 }
644
645 ret = ext4_write_checks(iocb, from);
646 if (ret <= 0)
647 goto out;
648
649 offset = iocb->ki_pos;
650 count = iov_iter_count(from);
651
652 if (offset + count > EXT4_I(inode)->i_disksize) {
653 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
654 if (IS_ERR(handle)) {
655 ret = PTR_ERR(handle);
656 goto out;
657 }
658
659 ret = ext4_orphan_add(handle, inode);
660 if (ret) {
661 ext4_journal_stop(handle);
662 goto out;
663 }
664
665 extend = true;
666 ext4_journal_stop(handle);
667 }
668
669 ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
670
671 if (extend) {
672 ret = ext4_handle_inode_extension(inode, offset, ret);
673 ext4_inode_extension_cleanup(inode, ret);
674 }
675 out:
676 inode_unlock(inode);
677 if (ret > 0)
678 ret = generic_write_sync(iocb, ret);
679 return ret;
680 }
681 #endif
682
683 static ssize_t
684 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
685 {
686 struct inode *inode = file_inode(iocb->ki_filp);
687
688 if (unlikely(ext4_forced_shutdown(inode->i_sb)))
689 return -EIO;
690
691 #ifdef CONFIG_FS_DAX
692 if (IS_DAX(inode))
693 return ext4_dax_write_iter(iocb, from);
694 #endif
695 if (iocb->ki_flags & IOCB_DIRECT)
696 return ext4_dio_write_iter(iocb, from);
697 else
698 return ext4_buffered_write_iter(iocb, from);
699 }
700
701 #ifdef CONFIG_FS_DAX
702 static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf, unsigned int order)
703 {
704 int error = 0;
705 vm_fault_t result;
706 int retries = 0;
707 handle_t *handle = NULL;
708 struct inode *inode = file_inode(vmf->vma->vm_file);
709 struct super_block *sb = inode->i_sb;
710
711 /*
712 * We have to distinguish real writes from writes which will result in a
713 * COW page; COW writes should *not* poke the journal (the file will not
714 * be changed). Doing so would cause unintended failures when mounted
715 * read-only.
716 *
717 * We check for VM_SHARED rather than vmf->cow_page since the latter is
718 * unset for order != 0 (i.e. only in do_cow_fault); for
719 * other sizes, dax_iomap_fault will handle splitting / fallback so that
720 * we eventually come back with a COW page.
721 */
722 bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
723 (vmf->vma->vm_flags & VM_SHARED);
724 struct address_space *mapping = vmf->vma->vm_file->f_mapping;
725 pfn_t pfn;
726
727 if (write) {
728 sb_start_pagefault(sb);
729 file_update_time(vmf->vma->vm_file);
730 filemap_invalidate_lock_shared(mapping);
731 retry:
732 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
733 EXT4_DATA_TRANS_BLOCKS(sb));
734 if (IS_ERR(handle)) {
735 filemap_invalidate_unlock_shared(mapping);
736 sb_end_pagefault(sb);
737 return VM_FAULT_SIGBUS;
738 }
739 } else {
740 filemap_invalidate_lock_shared(mapping);
741 }
742 result = dax_iomap_fault(vmf, order, &pfn, &error, &ext4_iomap_ops);
743 if (write) {
744 ext4_journal_stop(handle);
745
746 if ((result & VM_FAULT_ERROR) && error == -ENOSPC &&
747 ext4_should_retry_alloc(sb, &retries))
748 goto retry;
749 /* Handling synchronous page fault? */
750 if (result & VM_FAULT_NEEDDSYNC)
751 result = dax_finish_sync_fault(vmf, order, pfn);
752 filemap_invalidate_unlock_shared(mapping);
753 sb_end_pagefault(sb);
754 } else {
755 filemap_invalidate_unlock_shared(mapping);
756 }
757
758 return result;
759 }
760
761 static vm_fault_t ext4_dax_fault(struct vm_fault *vmf)
762 {
763 return ext4_dax_huge_fault(vmf, 0);
764 }
765
766 static const struct vm_operations_struct ext4_dax_vm_ops = {
767 .fault = ext4_dax_fault,
768 .huge_fault = ext4_dax_huge_fault,
769 .page_mkwrite = ext4_dax_fault,
770 .pfn_mkwrite = ext4_dax_fault,
771 };
772 #else
773 #define ext4_dax_vm_ops ext4_file_vm_ops
774 #endif
775
776 static const struct vm_operations_struct ext4_file_vm_ops = {
777 .fault = filemap_fault,
778 .map_pages = filemap_map_pages,
779 .page_mkwrite = ext4_page_mkwrite,
780 };
781
782 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
783 {
784 struct inode *inode = file->f_mapping->host;
785 struct dax_device *dax_dev = EXT4_SB(inode->i_sb)->s_daxdev;
786
787 if (unlikely(ext4_forced_shutdown(inode->i_sb)))
788 return -EIO;
789
790 /*
791 * We don't support synchronous mappings for non-DAX files and
792 * for DAX files if underneath dax_device is not synchronous.
793 */
794 if (!daxdev_mapping_supported(vma, dax_dev))
795 return -EOPNOTSUPP;
796
797 file_accessed(file);
798 if (IS_DAX(file_inode(file))) {
799 vma->vm_ops = &ext4_dax_vm_ops;
800 vm_flags_set(vma, VM_HUGEPAGE);
801 } else {
802 vma->vm_ops = &ext4_file_vm_ops;
803 }
804 return 0;
805 }
806
807 static int ext4_sample_last_mounted(struct super_block *sb,
808 struct vfsmount *mnt)
809 {
810 struct ext4_sb_info *sbi = EXT4_SB(sb);
811 struct path path;
812 char buf[64], *cp;
813 handle_t *handle;
814 int err;
815
816 if (likely(ext4_test_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED)))
817 return 0;
818
819 if (sb_rdonly(sb) || !sb_start_intwrite_trylock(sb))
820 return 0;
821
822 ext4_set_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED);
823 /*
824 * Sample where the filesystem has been mounted and
825 * store it in the superblock for sysadmin convenience
826 * when trying to sort through large numbers of block
827 * devices or filesystem images.
828 */
829 memset(buf, 0, sizeof(buf));
830 path.mnt = mnt;
831 path.dentry = mnt->mnt_root;
832 cp = d_path(&path, buf, sizeof(buf));
833 err = 0;
834 if (IS_ERR(cp))
835 goto out;
836
837 handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
838 err = PTR_ERR(handle);
839 if (IS_ERR(handle))
840 goto out;
841 BUFFER_TRACE(sbi->s_sbh, "get_write_access");
842 err = ext4_journal_get_write_access(handle, sb, sbi->s_sbh,
843 EXT4_JTR_NONE);
844 if (err)
845 goto out_journal;
846 lock_buffer(sbi->s_sbh);
847 strtomem_pad(sbi->s_es->s_last_mounted, cp, 0);
848 ext4_superblock_csum_set(sb);
849 unlock_buffer(sbi->s_sbh);
850 ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
851 out_journal:
852 ext4_journal_stop(handle);
853 out:
854 sb_end_intwrite(sb);
855 return err;
856 }
857
858 static int ext4_file_open(struct inode *inode, struct file *filp)
859 {
860 int ret;
861
862 if (unlikely(ext4_forced_shutdown(inode->i_sb)))
863 return -EIO;
864
865 ret = ext4_sample_last_mounted(inode->i_sb, filp->f_path.mnt);
866 if (ret)
867 return ret;
868
869 ret = fscrypt_file_open(inode, filp);
870 if (ret)
871 return ret;
872
873 ret = fsverity_file_open(inode, filp);
874 if (ret)
875 return ret;
876
877 /*
878 * Set up the jbd2_inode if we are opening the inode for
879 * writing and the journal is present
880 */
881 if (filp->f_mode & FMODE_WRITE) {
882 ret = ext4_inode_attach_jinode(inode);
883 if (ret < 0)
884 return ret;
885 }
886
887 filp->f_mode |= FMODE_NOWAIT | FMODE_CAN_ODIRECT;
888 return dquot_file_open(inode, filp);
889 }
890
891 /*
892 * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
893 * by calling generic_file_llseek_size() with the appropriate maxbytes
894 * value for each.
895 */
896 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
897 {
898 struct inode *inode = file->f_mapping->host;
899 loff_t maxbytes;
900
901 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
902 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
903 else
904 maxbytes = inode->i_sb->s_maxbytes;
905
906 switch (whence) {
907 default:
908 return generic_file_llseek_size(file, offset, whence,
909 maxbytes, i_size_read(inode));
910 case SEEK_HOLE:
911 inode_lock_shared(inode);
912 offset = iomap_seek_hole(inode, offset,
913 &ext4_iomap_report_ops);
914 inode_unlock_shared(inode);
915 break;
916 case SEEK_DATA:
917 inode_lock_shared(inode);
918 offset = iomap_seek_data(inode, offset,
919 &ext4_iomap_report_ops);
920 inode_unlock_shared(inode);
921 break;
922 }
923
924 if (offset < 0)
925 return offset;
926 return vfs_setpos(file, offset, maxbytes);
927 }
928
929 const struct file_operations ext4_file_operations = {
930 .llseek = ext4_llseek,
931 .read_iter = ext4_file_read_iter,
932 .write_iter = ext4_file_write_iter,
933 .iopoll = iocb_bio_iopoll,
934 .unlocked_ioctl = ext4_ioctl,
935 #ifdef CONFIG_COMPAT
936 .compat_ioctl = ext4_compat_ioctl,
937 #endif
938 .mmap = ext4_file_mmap,
939 .open = ext4_file_open,
940 .release = ext4_release_file,
941 .fsync = ext4_sync_file,
942 .get_unmapped_area = thp_get_unmapped_area,
943 .splice_read = ext4_file_splice_read,
944 .splice_write = iter_file_splice_write,
945 .fallocate = ext4_fallocate,
946 .fop_flags = FOP_MMAP_SYNC | FOP_BUFFER_RASYNC |
947 FOP_DIO_PARALLEL_WRITE,
948 };
949
950 const struct inode_operations ext4_file_inode_operations = {
951 .setattr = ext4_setattr,
952 .getattr = ext4_file_getattr,
953 .listxattr = ext4_listxattr,
954 .get_inode_acl = ext4_get_acl,
955 .set_acl = ext4_set_acl,
956 .fiemap = ext4_fiemap,
957 .fileattr_get = ext4_fileattr_get,
958 .fileattr_set = ext4_fileattr_set,
959 };
960
961
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