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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(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(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
102static 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
130static 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(EXT4_SB(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/*
151 * Called when an inode is released. Note that this is different
152 * from ext4_file_open: open gets called at every open, but release
153 * gets called only when /all/ the files are closed.
154 */
155static int ext4_release_file(struct inode *inode, struct file *filp)
156{
157 if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
158 ext4_alloc_da_blocks(inode);
159 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
160 }
161 /* if we are the last writer on the inode, drop the block reservation */
162 if ((filp->f_mode & FMODE_WRITE) &&
163 (atomic_read(&inode->i_writecount) == 1) &&
164 !EXT4_I(inode)->i_reserved_data_blocks) {
165 down_write(&EXT4_I(inode)->i_data_sem);
166 ext4_discard_preallocations(inode, 0);
167 up_write(&EXT4_I(inode)->i_data_sem);
168 }
169 if (is_dx(inode) && filp->private_data)
170 ext4_htree_free_dir_info(filp->private_data);
171
172 return 0;
173}
174
175/*
176 * This tests whether the IO in question is block-aligned or not.
177 * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
178 * are converted to written only after the IO is complete. Until they are
179 * mapped, these blocks appear as holes, so dio_zero_block() will assume that
180 * it needs to zero out portions of the start and/or end block. If 2 AIO
181 * threads are at work on the same unwritten block, they must be synchronized
182 * or one thread will zero the other's data, causing corruption.
183 */
184static bool
185ext4_unaligned_io(struct inode *inode, struct iov_iter *from, loff_t pos)
186{
187 struct super_block *sb = inode->i_sb;
188 unsigned long blockmask = sb->s_blocksize - 1;
189
190 if ((pos | iov_iter_alignment(from)) & blockmask)
191 return true;
192
193 return false;
194}
195
196static bool
197ext4_extending_io(struct inode *inode, loff_t offset, size_t len)
198{
199 if (offset + len > i_size_read(inode) ||
200 offset + len > EXT4_I(inode)->i_disksize)
201 return true;
202 return false;
203}
204
205/* Is IO overwriting allocated and initialized blocks? */
206static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len)
207{
208 struct ext4_map_blocks map;
209 unsigned int blkbits = inode->i_blkbits;
210 int err, blklen;
211
212 if (pos + len > i_size_read(inode))
213 return false;
214
215 map.m_lblk = pos >> blkbits;
216 map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
217 blklen = map.m_len;
218
219 err = ext4_map_blocks(NULL, inode, &map, 0);
220 /*
221 * 'err==len' means that all of the blocks have been preallocated,
222 * regardless of whether they have been initialized or not. To exclude
223 * unwritten extents, we need to check m_flags.
224 */
225 return err == blklen && (map.m_flags & EXT4_MAP_MAPPED);
226}
227
228static ssize_t ext4_generic_write_checks(struct kiocb *iocb,
229 struct iov_iter *from)
230{
231 struct inode *inode = file_inode(iocb->ki_filp);
232 ssize_t ret;
233
234 if (unlikely(IS_IMMUTABLE(inode)))
235 return -EPERM;
236
237 ret = generic_write_checks(iocb, from);
238 if (ret <= 0)
239 return ret;
240
241 /*
242 * If we have encountered a bitmap-format file, the size limit
243 * is smaller than s_maxbytes, which is for extent-mapped files.
244 */
245 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
246 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
247
248 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
249 return -EFBIG;
250 iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
251 }
252
253 return iov_iter_count(from);
254}
255
256static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
257{
258 ssize_t ret, count;
259
260 count = ext4_generic_write_checks(iocb, from);
261 if (count <= 0)
262 return count;
263
264 ret = file_modified(iocb->ki_filp);
265 if (ret)
266 return ret;
267 return count;
268}
269
270static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
271 struct iov_iter *from)
272{
273 ssize_t ret;
274 struct inode *inode = file_inode(iocb->ki_filp);
275
276 if (iocb->ki_flags & IOCB_NOWAIT)
277 return -EOPNOTSUPP;
278
279 inode_lock(inode);
280 ret = ext4_write_checks(iocb, from);
281 if (ret <= 0)
282 goto out;
283
284 current->backing_dev_info = inode_to_bdi(inode);
285 ret = generic_perform_write(iocb, from);
286 current->backing_dev_info = NULL;
287
288out:
289 inode_unlock(inode);
290 if (likely(ret > 0)) {
291 iocb->ki_pos += ret;
292 ret = generic_write_sync(iocb, ret);
293 }
294
295 return ret;
296}
297
298static ssize_t ext4_handle_inode_extension(struct inode *inode, loff_t offset,
299 ssize_t written, size_t count)
300{
301 handle_t *handle;
302 bool truncate = false;
303 u8 blkbits = inode->i_blkbits;
304 ext4_lblk_t written_blk, end_blk;
305 int ret;
306
307 /*
308 * Note that EXT4_I(inode)->i_disksize can get extended up to
309 * inode->i_size while the I/O was running due to writeback of delalloc
310 * blocks. But, the code in ext4_iomap_alloc() is careful to use
311 * zeroed/unwritten extents if this is possible; thus we won't leave
312 * uninitialized blocks in a file even if we didn't succeed in writing
313 * as much as we intended.
314 */
315 WARN_ON_ONCE(i_size_read(inode) < EXT4_I(inode)->i_disksize);
316 if (offset + count <= EXT4_I(inode)->i_disksize) {
317 /*
318 * We need to ensure that the inode is removed from the orphan
319 * list if it has been added prematurely, due to writeback of
320 * delalloc blocks.
321 */
322 if (!list_empty(&EXT4_I(inode)->i_orphan) && inode->i_nlink) {
323 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
324
325 if (IS_ERR(handle)) {
326 ext4_orphan_del(NULL, inode);
327 return PTR_ERR(handle);
328 }
329
330 ext4_orphan_del(handle, inode);
331 ext4_journal_stop(handle);
332 }
333
334 return written;
335 }
336
337 if (written < 0)
338 goto truncate;
339
340 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
341 if (IS_ERR(handle)) {
342 written = PTR_ERR(handle);
343 goto truncate;
344 }
345
346 if (ext4_update_inode_size(inode, offset + written)) {
347 ret = ext4_mark_inode_dirty(handle, inode);
348 if (unlikely(ret)) {
349 written = ret;
350 ext4_journal_stop(handle);
351 goto truncate;
352 }
353 }
354
355 /*
356 * We may need to truncate allocated but not written blocks beyond EOF.
357 */
358 written_blk = ALIGN(offset + written, 1 << blkbits);
359 end_blk = ALIGN(offset + count, 1 << blkbits);
360 if (written_blk < end_blk && ext4_can_truncate(inode))
361 truncate = true;
362
363 /*
364 * Remove the inode from the orphan list if it has been extended and
365 * everything went OK.
366 */
367 if (!truncate && inode->i_nlink)
368 ext4_orphan_del(handle, inode);
369 ext4_journal_stop(handle);
370
371 if (truncate) {
372truncate:
373 ext4_truncate_failed_write(inode);
374 /*
375 * If the truncate operation failed early, then the inode may
376 * still be on the orphan list. In that case, we need to try
377 * remove the inode from the in-memory linked list.
378 */
379 if (inode->i_nlink)
380 ext4_orphan_del(NULL, inode);
381 }
382
383 return written;
384}
385
386static int ext4_dio_write_end_io(struct kiocb *iocb, ssize_t size,
387 int error, unsigned int flags)
388{
389 loff_t pos = iocb->ki_pos;
390 struct inode *inode = file_inode(iocb->ki_filp);
391
392 if (error)
393 return error;
394
395 if (size && flags & IOMAP_DIO_UNWRITTEN) {
396 error = ext4_convert_unwritten_extents(NULL, inode, pos, size);
397 if (error < 0)
398 return error;
399 }
400 /*
401 * If we are extending the file, we have to update i_size here before
402 * page cache gets invalidated in iomap_dio_rw(). Otherwise racing
403 * buffered reads could zero out too much from page cache pages. Update
404 * of on-disk size will happen later in ext4_dio_write_iter() where
405 * we have enough information to also perform orphan list handling etc.
406 * Note that we perform all extending writes synchronously under
407 * i_rwsem held exclusively so i_size update is safe here in that case.
408 * If the write was not extending, we cannot see pos > i_size here
409 * because operations reducing i_size like truncate wait for all
410 * outstanding DIO before updating i_size.
411 */
412 pos += size;
413 if (pos > i_size_read(inode))
414 i_size_write(inode, pos);
415
416 return 0;
417}
418
419static const struct iomap_dio_ops ext4_dio_write_ops = {
420 .end_io = ext4_dio_write_end_io,
421};
422
423/*
424 * The intention here is to start with shared lock acquired then see if any
425 * condition requires an exclusive inode lock. If yes, then we restart the
426 * whole operation by releasing the shared lock and acquiring exclusive lock.
427 *
428 * - For unaligned_io we never take shared lock as it may cause data corruption
429 * when two unaligned IO tries to modify the same block e.g. while zeroing.
430 *
431 * - For extending writes case we don't take the shared lock, since it requires
432 * updating inode i_disksize and/or orphan handling with exclusive lock.
433 *
434 * - shared locking will only be true mostly with overwrites. Otherwise we will
435 * switch to exclusive i_rwsem lock.
436 */
437static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from,
438 bool *ilock_shared, bool *extend)
439{
440 struct file *file = iocb->ki_filp;
441 struct inode *inode = file_inode(file);
442 loff_t offset;
443 size_t count;
444 ssize_t ret;
445
446restart:
447 ret = ext4_generic_write_checks(iocb, from);
448 if (ret <= 0)
449 goto out;
450
451 offset = iocb->ki_pos;
452 count = ret;
453 if (ext4_extending_io(inode, offset, count))
454 *extend = true;
455 /*
456 * Determine whether the IO operation will overwrite allocated
457 * and initialized blocks.
458 * We need exclusive i_rwsem for changing security info
459 * in file_modified().
460 */
461 if (*ilock_shared && (!IS_NOSEC(inode) || *extend ||
462 !ext4_overwrite_io(inode, offset, count))) {
463 if (iocb->ki_flags & IOCB_NOWAIT) {
464 ret = -EAGAIN;
465 goto out;
466 }
467 inode_unlock_shared(inode);
468 *ilock_shared = false;
469 inode_lock(inode);
470 goto restart;
471 }
472
473 ret = file_modified(file);
474 if (ret < 0)
475 goto out;
476
477 return count;
478out:
479 if (*ilock_shared)
480 inode_unlock_shared(inode);
481 else
482 inode_unlock(inode);
483 return ret;
484}
485
486static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
487{
488 ssize_t ret;
489 handle_t *handle;
490 struct inode *inode = file_inode(iocb->ki_filp);
491 loff_t offset = iocb->ki_pos;
492 size_t count = iov_iter_count(from);
493 const struct iomap_ops *iomap_ops = &ext4_iomap_ops;
494 bool extend = false, unaligned_io = false;
495 bool ilock_shared = true;
496
497 /*
498 * We initially start with shared inode lock unless it is
499 * unaligned IO which needs exclusive lock anyways.
500 */
501 if (ext4_unaligned_io(inode, from, offset)) {
502 unaligned_io = true;
503 ilock_shared = false;
504 }
505 /*
506 * Quick check here without any i_rwsem lock to see if it is extending
507 * IO. A more reliable check is done in ext4_dio_write_checks() with
508 * proper locking in place.
509 */
510 if (offset + count > i_size_read(inode))
511 ilock_shared = false;
512
513 if (iocb->ki_flags & IOCB_NOWAIT) {
514 if (ilock_shared) {
515 if (!inode_trylock_shared(inode))
516 return -EAGAIN;
517 } else {
518 if (!inode_trylock(inode))
519 return -EAGAIN;
520 }
521 } else {
522 if (ilock_shared)
523 inode_lock_shared(inode);
524 else
525 inode_lock(inode);
526 }
527
528 /* Fallback to buffered I/O if the inode does not support direct I/O. */
529 if (!ext4_should_use_dio(iocb, from)) {
530 if (ilock_shared)
531 inode_unlock_shared(inode);
532 else
533 inode_unlock(inode);
534 return ext4_buffered_write_iter(iocb, from);
535 }
536
537 ret = ext4_dio_write_checks(iocb, from, &ilock_shared, &extend);
538 if (ret <= 0)
539 return ret;
540
541 /* if we're going to block and IOCB_NOWAIT is set, return -EAGAIN */
542 if ((iocb->ki_flags & IOCB_NOWAIT) && (unaligned_io || extend)) {
543 ret = -EAGAIN;
544 goto out;
545 }
546 /*
547 * Make sure inline data cannot be created anymore since we are going
548 * to allocate blocks for DIO. We know the inode does not have any
549 * inline data now because ext4_dio_supported() checked for that.
550 */
551 ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
552
553 offset = iocb->ki_pos;
554 count = ret;
555
556 /*
557 * Unaligned direct IO must be serialized among each other as zeroing
558 * of partial blocks of two competing unaligned IOs can result in data
559 * corruption.
560 *
561 * So we make sure we don't allow any unaligned IO in flight.
562 * For IOs where we need not wait (like unaligned non-AIO DIO),
563 * below inode_dio_wait() may anyway become a no-op, since we start
564 * with exclusive lock.
565 */
566 if (unaligned_io)
567 inode_dio_wait(inode);
568
569 if (extend) {
570 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
571 if (IS_ERR(handle)) {
572 ret = PTR_ERR(handle);
573 goto out;
574 }
575
576 ret = ext4_orphan_add(handle, inode);
577 if (ret) {
578 ext4_journal_stop(handle);
579 goto out;
580 }
581
582 ext4_journal_stop(handle);
583 }
584
585 if (ilock_shared)
586 iomap_ops = &ext4_iomap_overwrite_ops;
587 ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops,
588 (unaligned_io || extend) ? IOMAP_DIO_FORCE_WAIT : 0,
589 NULL, 0);
590 if (ret == -ENOTBLK)
591 ret = 0;
592
593 if (extend)
594 ret = ext4_handle_inode_extension(inode, offset, ret, count);
595
596out:
597 if (ilock_shared)
598 inode_unlock_shared(inode);
599 else
600 inode_unlock(inode);
601
602 if (ret >= 0 && iov_iter_count(from)) {
603 ssize_t err;
604 loff_t endbyte;
605
606 offset = iocb->ki_pos;
607 err = ext4_buffered_write_iter(iocb, from);
608 if (err < 0)
609 return err;
610
611 /*
612 * We need to ensure that the pages within the page cache for
613 * the range covered by this I/O are written to disk and
614 * invalidated. This is in attempt to preserve the expected
615 * direct I/O semantics in the case we fallback to buffered I/O
616 * to complete off the I/O request.
617 */
618 ret += err;
619 endbyte = offset + err - 1;
620 err = filemap_write_and_wait_range(iocb->ki_filp->f_mapping,
621 offset, endbyte);
622 if (!err)
623 invalidate_mapping_pages(iocb->ki_filp->f_mapping,
624 offset >> PAGE_SHIFT,
625 endbyte >> PAGE_SHIFT);
626 }
627
628 return ret;
629}
630
631#ifdef CONFIG_FS_DAX
632static ssize_t
633ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
634{
635 ssize_t ret;
636 size_t count;
637 loff_t offset;
638 handle_t *handle;
639 bool extend = false;
640 struct inode *inode = file_inode(iocb->ki_filp);
641
642 if (iocb->ki_flags & IOCB_NOWAIT) {
643 if (!inode_trylock(inode))
644 return -EAGAIN;
645 } else {
646 inode_lock(inode);
647 }
648
649 ret = ext4_write_checks(iocb, from);
650 if (ret <= 0)
651 goto out;
652
653 offset = iocb->ki_pos;
654 count = iov_iter_count(from);
655
656 if (offset + count > EXT4_I(inode)->i_disksize) {
657 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
658 if (IS_ERR(handle)) {
659 ret = PTR_ERR(handle);
660 goto out;
661 }
662
663 ret = ext4_orphan_add(handle, inode);
664 if (ret) {
665 ext4_journal_stop(handle);
666 goto out;
667 }
668
669 extend = true;
670 ext4_journal_stop(handle);
671 }
672
673 ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
674
675 if (extend)
676 ret = ext4_handle_inode_extension(inode, offset, ret, count);
677out:
678 inode_unlock(inode);
679 if (ret > 0)
680 ret = generic_write_sync(iocb, ret);
681 return ret;
682}
683#endif
684
685static ssize_t
686ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
687{
688 struct inode *inode = file_inode(iocb->ki_filp);
689
690 if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
691 return -EIO;
692
693#ifdef CONFIG_FS_DAX
694 if (IS_DAX(inode))
695 return ext4_dax_write_iter(iocb, from);
696#endif
697 if (iocb->ki_flags & IOCB_DIRECT)
698 return ext4_dio_write_iter(iocb, from);
699 else
700 return ext4_buffered_write_iter(iocb, from);
701}
702
703#ifdef CONFIG_FS_DAX
704static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf,
705 enum page_entry_size pe_size)
706{
707 int error = 0;
708 vm_fault_t result;
709 int retries = 0;
710 handle_t *handle = NULL;
711 struct inode *inode = file_inode(vmf->vma->vm_file);
712 struct super_block *sb = inode->i_sb;
713
714 /*
715 * We have to distinguish real writes from writes which will result in a
716 * COW page; COW writes should *not* poke the journal (the file will not
717 * be changed). Doing so would cause unintended failures when mounted
718 * read-only.
719 *
720 * We check for VM_SHARED rather than vmf->cow_page since the latter is
721 * unset for pe_size != PE_SIZE_PTE (i.e. only in do_cow_fault); for
722 * other sizes, dax_iomap_fault will handle splitting / fallback so that
723 * we eventually come back with a COW page.
724 */
725 bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
726 (vmf->vma->vm_flags & VM_SHARED);
727 struct address_space *mapping = vmf->vma->vm_file->f_mapping;
728 pfn_t pfn;
729
730 if (write) {
731 sb_start_pagefault(sb);
732 file_update_time(vmf->vma->vm_file);
733 filemap_invalidate_lock_shared(mapping);
734retry:
735 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
736 EXT4_DATA_TRANS_BLOCKS(sb));
737 if (IS_ERR(handle)) {
738 filemap_invalidate_unlock_shared(mapping);
739 sb_end_pagefault(sb);
740 return VM_FAULT_SIGBUS;
741 }
742 } else {
743 filemap_invalidate_lock_shared(mapping);
744 }
745 result = dax_iomap_fault(vmf, pe_size, &pfn, &error, &ext4_iomap_ops);
746 if (write) {
747 ext4_journal_stop(handle);
748
749 if ((result & VM_FAULT_ERROR) && error == -ENOSPC &&
750 ext4_should_retry_alloc(sb, &retries))
751 goto retry;
752 /* Handling synchronous page fault? */
753 if (result & VM_FAULT_NEEDDSYNC)
754 result = dax_finish_sync_fault(vmf, pe_size, pfn);
755 filemap_invalidate_unlock_shared(mapping);
756 sb_end_pagefault(sb);
757 } else {
758 filemap_invalidate_unlock_shared(mapping);
759 }
760
761 return result;
762}
763
764static vm_fault_t ext4_dax_fault(struct vm_fault *vmf)
765{
766 return ext4_dax_huge_fault(vmf, PE_SIZE_PTE);
767}
768
769static const struct vm_operations_struct ext4_dax_vm_ops = {
770 .fault = ext4_dax_fault,
771 .huge_fault = ext4_dax_huge_fault,
772 .page_mkwrite = ext4_dax_fault,
773 .pfn_mkwrite = ext4_dax_fault,
774};
775#else
776#define ext4_dax_vm_ops ext4_file_vm_ops
777#endif
778
779static const struct vm_operations_struct ext4_file_vm_ops = {
780 .fault = filemap_fault,
781 .map_pages = filemap_map_pages,
782 .page_mkwrite = ext4_page_mkwrite,
783};
784
785static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
786{
787 struct inode *inode = file->f_mapping->host;
788 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
789 struct dax_device *dax_dev = sbi->s_daxdev;
790
791 if (unlikely(ext4_forced_shutdown(sbi)))
792 return -EIO;
793
794 /*
795 * We don't support synchronous mappings for non-DAX files and
796 * for DAX files if underneath dax_device is not synchronous.
797 */
798 if (!daxdev_mapping_supported(vma, dax_dev))
799 return -EOPNOTSUPP;
800
801 file_accessed(file);
802 if (IS_DAX(file_inode(file))) {
803 vma->vm_ops = &ext4_dax_vm_ops;
804 vma->vm_flags |= VM_HUGEPAGE;
805 } else {
806 vma->vm_ops = &ext4_file_vm_ops;
807 }
808 return 0;
809}
810
811static int ext4_sample_last_mounted(struct super_block *sb,
812 struct vfsmount *mnt)
813{
814 struct ext4_sb_info *sbi = EXT4_SB(sb);
815 struct path path;
816 char buf[64], *cp;
817 handle_t *handle;
818 int err;
819
820 if (likely(ext4_test_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED)))
821 return 0;
822
823 if (sb_rdonly(sb) || !sb_start_intwrite_trylock(sb))
824 return 0;
825
826 ext4_set_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED);
827 /*
828 * Sample where the filesystem has been mounted and
829 * store it in the superblock for sysadmin convenience
830 * when trying to sort through large numbers of block
831 * devices or filesystem images.
832 */
833 memset(buf, 0, sizeof(buf));
834 path.mnt = mnt;
835 path.dentry = mnt->mnt_root;
836 cp = d_path(&path, buf, sizeof(buf));
837 err = 0;
838 if (IS_ERR(cp))
839 goto out;
840
841 handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
842 err = PTR_ERR(handle);
843 if (IS_ERR(handle))
844 goto out;
845 BUFFER_TRACE(sbi->s_sbh, "get_write_access");
846 err = ext4_journal_get_write_access(handle, sb, sbi->s_sbh,
847 EXT4_JTR_NONE);
848 if (err)
849 goto out_journal;
850 lock_buffer(sbi->s_sbh);
851 strncpy(sbi->s_es->s_last_mounted, cp,
852 sizeof(sbi->s_es->s_last_mounted));
853 ext4_superblock_csum_set(sb);
854 unlock_buffer(sbi->s_sbh);
855 ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
856out_journal:
857 ext4_journal_stop(handle);
858out:
859 sb_end_intwrite(sb);
860 return err;
861}
862
863static int ext4_file_open(struct inode *inode, struct file *filp)
864{
865 int ret;
866
867 if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
868 return -EIO;
869
870 ret = ext4_sample_last_mounted(inode->i_sb, filp->f_path.mnt);
871 if (ret)
872 return ret;
873
874 ret = fscrypt_file_open(inode, filp);
875 if (ret)
876 return ret;
877
878 ret = fsverity_file_open(inode, filp);
879 if (ret)
880 return ret;
881
882 /*
883 * Set up the jbd2_inode if we are opening the inode for
884 * writing and the journal is present
885 */
886 if (filp->f_mode & FMODE_WRITE) {
887 ret = ext4_inode_attach_jinode(inode);
888 if (ret < 0)
889 return ret;
890 }
891
892 filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
893 return dquot_file_open(inode, filp);
894}
895
896/*
897 * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
898 * by calling generic_file_llseek_size() with the appropriate maxbytes
899 * value for each.
900 */
901loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
902{
903 struct inode *inode = file->f_mapping->host;
904 loff_t maxbytes;
905
906 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
907 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
908 else
909 maxbytes = inode->i_sb->s_maxbytes;
910
911 switch (whence) {
912 default:
913 return generic_file_llseek_size(file, offset, whence,
914 maxbytes, i_size_read(inode));
915 case SEEK_HOLE:
916 inode_lock_shared(inode);
917 offset = iomap_seek_hole(inode, offset,
918 &ext4_iomap_report_ops);
919 inode_unlock_shared(inode);
920 break;
921 case SEEK_DATA:
922 inode_lock_shared(inode);
923 offset = iomap_seek_data(inode, offset,
924 &ext4_iomap_report_ops);
925 inode_unlock_shared(inode);
926 break;
927 }
928
929 if (offset < 0)
930 return offset;
931 return vfs_setpos(file, offset, maxbytes);
932}
933
934const struct file_operations ext4_file_operations = {
935 .llseek = ext4_llseek,
936 .read_iter = ext4_file_read_iter,
937 .write_iter = ext4_file_write_iter,
938 .iopoll = iocb_bio_iopoll,
939 .unlocked_ioctl = ext4_ioctl,
940#ifdef CONFIG_COMPAT
941 .compat_ioctl = ext4_compat_ioctl,
942#endif
943 .mmap = ext4_file_mmap,
944 .mmap_supported_flags = MAP_SYNC,
945 .open = ext4_file_open,
946 .release = ext4_release_file,
947 .fsync = ext4_sync_file,
948 .get_unmapped_area = thp_get_unmapped_area,
949 .splice_read = generic_file_splice_read,
950 .splice_write = iter_file_splice_write,
951 .fallocate = ext4_fallocate,
952};
953
954const struct inode_operations ext4_file_inode_operations = {
955 .setattr = ext4_setattr,
956 .getattr = ext4_file_getattr,
957 .listxattr = ext4_listxattr,
958 .get_inode_acl = ext4_get_acl,
959 .set_acl = ext4_set_acl,
960 .fiemap = ext4_fiemap,
961 .fileattr_get = ext4_fileattr_get,
962 .fileattr_set = ext4_fileattr_set,
963};
964
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#ifdef CONFIG_FS_DAX
35static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
36{
37 struct inode *inode = file_inode(iocb->ki_filp);
38 ssize_t ret;
39
40 inode_lock_shared(inode);
41 /*
42 * Recheck under inode lock - at this point we are sure it cannot
43 * change anymore
44 */
45 if (!IS_DAX(inode)) {
46 inode_unlock_shared(inode);
47 /* Fallback to buffered IO in case we cannot support DAX */
48 return generic_file_read_iter(iocb, to);
49 }
50 ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
51 inode_unlock_shared(inode);
52
53 file_accessed(iocb->ki_filp);
54 return ret;
55}
56#endif
57
58static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
59{
60 if (!iov_iter_count(to))
61 return 0; /* skip atime */
62
63#ifdef CONFIG_FS_DAX
64 if (IS_DAX(file_inode(iocb->ki_filp)))
65 return ext4_dax_read_iter(iocb, to);
66#endif
67 return generic_file_read_iter(iocb, to);
68}
69
70/*
71 * Called when an inode is released. Note that this is different
72 * from ext4_file_open: open gets called at every open, but release
73 * gets called only when /all/ the files are closed.
74 */
75static int ext4_release_file(struct inode *inode, struct file *filp)
76{
77 if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
78 ext4_alloc_da_blocks(inode);
79 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
80 }
81 /* if we are the last writer on the inode, drop the block reservation */
82 if ((filp->f_mode & FMODE_WRITE) &&
83 (atomic_read(&inode->i_writecount) == 1) &&
84 !EXT4_I(inode)->i_reserved_data_blocks)
85 {
86 down_write(&EXT4_I(inode)->i_data_sem);
87 ext4_discard_preallocations(inode);
88 up_write(&EXT4_I(inode)->i_data_sem);
89 }
90 if (is_dx(inode) && filp->private_data)
91 ext4_htree_free_dir_info(filp->private_data);
92
93 return 0;
94}
95
96static void ext4_unwritten_wait(struct inode *inode)
97{
98 wait_queue_head_t *wq = ext4_ioend_wq(inode);
99
100 wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_unwritten) == 0));
101}
102
103/*
104 * This tests whether the IO in question is block-aligned or not.
105 * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
106 * are converted to written only after the IO is complete. Until they are
107 * mapped, these blocks appear as holes, so dio_zero_block() will assume that
108 * it needs to zero out portions of the start and/or end block. If 2 AIO
109 * threads are at work on the same unwritten block, they must be synchronized
110 * or one thread will zero the other's data, causing corruption.
111 */
112static int
113ext4_unaligned_aio(struct inode *inode, struct iov_iter *from, loff_t pos)
114{
115 struct super_block *sb = inode->i_sb;
116 int blockmask = sb->s_blocksize - 1;
117
118 if (pos >= i_size_read(inode))
119 return 0;
120
121 if ((pos | iov_iter_alignment(from)) & blockmask)
122 return 1;
123
124 return 0;
125}
126
127/* Is IO overwriting allocated and initialized blocks? */
128static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len)
129{
130 struct ext4_map_blocks map;
131 unsigned int blkbits = inode->i_blkbits;
132 int err, blklen;
133
134 if (pos + len > i_size_read(inode))
135 return false;
136
137 map.m_lblk = pos >> blkbits;
138 map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
139 blklen = map.m_len;
140
141 err = ext4_map_blocks(NULL, inode, &map, 0);
142 /*
143 * 'err==len' means that all of the blocks have been preallocated,
144 * regardless of whether they have been initialized or not. To exclude
145 * unwritten extents, we need to check m_flags.
146 */
147 return err == blklen && (map.m_flags & EXT4_MAP_MAPPED);
148}
149
150static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
151{
152 struct inode *inode = file_inode(iocb->ki_filp);
153 ssize_t ret;
154
155 ret = generic_write_checks(iocb, from);
156 if (ret <= 0)
157 return ret;
158 /*
159 * If we have encountered a bitmap-format file, the size limit
160 * is smaller than s_maxbytes, which is for extent-mapped files.
161 */
162 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
163 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
164
165 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
166 return -EFBIG;
167 iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
168 }
169 return iov_iter_count(from);
170}
171
172#ifdef CONFIG_FS_DAX
173static ssize_t
174ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
175{
176 struct inode *inode = file_inode(iocb->ki_filp);
177 ssize_t ret;
178 bool overwrite = false;
179
180 inode_lock(inode);
181 ret = ext4_write_checks(iocb, from);
182 if (ret <= 0)
183 goto out;
184 ret = file_remove_privs(iocb->ki_filp);
185 if (ret)
186 goto out;
187 ret = file_update_time(iocb->ki_filp);
188 if (ret)
189 goto out;
190
191 if (ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from))) {
192 overwrite = true;
193 downgrade_write(&inode->i_rwsem);
194 }
195 ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
196out:
197 if (!overwrite)
198 inode_unlock(inode);
199 else
200 inode_unlock_shared(inode);
201 if (ret > 0)
202 ret = generic_write_sync(iocb, ret);
203 return ret;
204}
205#endif
206
207static ssize_t
208ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
209{
210 struct inode *inode = file_inode(iocb->ki_filp);
211 int o_direct = iocb->ki_flags & IOCB_DIRECT;
212 int unaligned_aio = 0;
213 int overwrite = 0;
214 ssize_t ret;
215
216#ifdef CONFIG_FS_DAX
217 if (IS_DAX(inode))
218 return ext4_dax_write_iter(iocb, from);
219#endif
220
221 inode_lock(inode);
222 ret = ext4_write_checks(iocb, from);
223 if (ret <= 0)
224 goto out;
225
226 /*
227 * Unaligned direct AIO must be serialized among each other as zeroing
228 * of partial blocks of two competing unaligned AIOs can result in data
229 * corruption.
230 */
231 if (o_direct && ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
232 !is_sync_kiocb(iocb) &&
233 ext4_unaligned_aio(inode, from, iocb->ki_pos)) {
234 unaligned_aio = 1;
235 ext4_unwritten_wait(inode);
236 }
237
238 iocb->private = &overwrite;
239 /* Check whether we do a DIO overwrite or not */
240 if (o_direct && ext4_should_dioread_nolock(inode) && !unaligned_aio &&
241 ext4_overwrite_io(inode, iocb->ki_pos, iov_iter_count(from)))
242 overwrite = 1;
243
244 ret = __generic_file_write_iter(iocb, from);
245 inode_unlock(inode);
246
247 if (ret > 0)
248 ret = generic_write_sync(iocb, ret);
249
250 return ret;
251
252out:
253 inode_unlock(inode);
254 return ret;
255}
256
257#ifdef CONFIG_FS_DAX
258static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
259{
260 int result;
261 struct inode *inode = file_inode(vma->vm_file);
262 struct super_block *sb = inode->i_sb;
263 bool write = vmf->flags & FAULT_FLAG_WRITE;
264
265 if (write) {
266 sb_start_pagefault(sb);
267 file_update_time(vma->vm_file);
268 }
269 down_read(&EXT4_I(inode)->i_mmap_sem);
270 result = dax_iomap_fault(vma, vmf, &ext4_iomap_ops);
271 up_read(&EXT4_I(inode)->i_mmap_sem);
272 if (write)
273 sb_end_pagefault(sb);
274
275 return result;
276}
277
278static int ext4_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
279 pmd_t *pmd, unsigned int flags)
280{
281 int result;
282 struct inode *inode = file_inode(vma->vm_file);
283 struct super_block *sb = inode->i_sb;
284 bool write = flags & FAULT_FLAG_WRITE;
285
286 if (write) {
287 sb_start_pagefault(sb);
288 file_update_time(vma->vm_file);
289 }
290 down_read(&EXT4_I(inode)->i_mmap_sem);
291 result = dax_iomap_pmd_fault(vma, addr, pmd, flags,
292 &ext4_iomap_ops);
293 up_read(&EXT4_I(inode)->i_mmap_sem);
294 if (write)
295 sb_end_pagefault(sb);
296
297 return result;
298}
299
300/*
301 * Handle write fault for VM_MIXEDMAP mappings. Similarly to ext4_dax_fault()
302 * handler we check for races agaist truncate. Note that since we cycle through
303 * i_mmap_sem, we are sure that also any hole punching that began before we
304 * were called is finished by now and so if it included part of the file we
305 * are working on, our pte will get unmapped and the check for pte_same() in
306 * wp_pfn_shared() fails. Thus fault gets retried and things work out as
307 * desired.
308 */
309static int ext4_dax_pfn_mkwrite(struct vm_area_struct *vma,
310 struct vm_fault *vmf)
311{
312 struct inode *inode = file_inode(vma->vm_file);
313 struct super_block *sb = inode->i_sb;
314 loff_t size;
315 int ret;
316
317 sb_start_pagefault(sb);
318 file_update_time(vma->vm_file);
319 down_read(&EXT4_I(inode)->i_mmap_sem);
320 size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
321 if (vmf->pgoff >= size)
322 ret = VM_FAULT_SIGBUS;
323 else
324 ret = dax_pfn_mkwrite(vma, vmf);
325 up_read(&EXT4_I(inode)->i_mmap_sem);
326 sb_end_pagefault(sb);
327
328 return ret;
329}
330
331static const struct vm_operations_struct ext4_dax_vm_ops = {
332 .fault = ext4_dax_fault,
333 .pmd_fault = ext4_dax_pmd_fault,
334 .page_mkwrite = ext4_dax_fault,
335 .pfn_mkwrite = ext4_dax_pfn_mkwrite,
336};
337#else
338#define ext4_dax_vm_ops ext4_file_vm_ops
339#endif
340
341static const struct vm_operations_struct ext4_file_vm_ops = {
342 .fault = ext4_filemap_fault,
343 .map_pages = filemap_map_pages,
344 .page_mkwrite = ext4_page_mkwrite,
345};
346
347static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
348{
349 struct inode *inode = file->f_mapping->host;
350
351 if (ext4_encrypted_inode(inode)) {
352 int err = fscrypt_get_encryption_info(inode);
353 if (err)
354 return 0;
355 if (!fscrypt_has_encryption_key(inode))
356 return -ENOKEY;
357 }
358 file_accessed(file);
359 if (IS_DAX(file_inode(file))) {
360 vma->vm_ops = &ext4_dax_vm_ops;
361 vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
362 } else {
363 vma->vm_ops = &ext4_file_vm_ops;
364 }
365 return 0;
366}
367
368static int ext4_file_open(struct inode * inode, struct file * filp)
369{
370 struct super_block *sb = inode->i_sb;
371 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
372 struct vfsmount *mnt = filp->f_path.mnt;
373 struct dentry *dir;
374 struct path path;
375 char buf[64], *cp;
376 int ret;
377
378 if (unlikely(!(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED) &&
379 !(sb->s_flags & MS_RDONLY))) {
380 sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
381 /*
382 * Sample where the filesystem has been mounted and
383 * store it in the superblock for sysadmin convenience
384 * when trying to sort through large numbers of block
385 * devices or filesystem images.
386 */
387 memset(buf, 0, sizeof(buf));
388 path.mnt = mnt;
389 path.dentry = mnt->mnt_root;
390 cp = d_path(&path, buf, sizeof(buf));
391 if (!IS_ERR(cp)) {
392 handle_t *handle;
393 int err;
394
395 handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
396 if (IS_ERR(handle))
397 return PTR_ERR(handle);
398 BUFFER_TRACE(sbi->s_sbh, "get_write_access");
399 err = ext4_journal_get_write_access(handle, sbi->s_sbh);
400 if (err) {
401 ext4_journal_stop(handle);
402 return err;
403 }
404 strlcpy(sbi->s_es->s_last_mounted, cp,
405 sizeof(sbi->s_es->s_last_mounted));
406 ext4_handle_dirty_super(handle, sb);
407 ext4_journal_stop(handle);
408 }
409 }
410 if (ext4_encrypted_inode(inode)) {
411 ret = fscrypt_get_encryption_info(inode);
412 if (ret)
413 return -EACCES;
414 if (!fscrypt_has_encryption_key(inode))
415 return -ENOKEY;
416 }
417
418 dir = dget_parent(file_dentry(filp));
419 if (ext4_encrypted_inode(d_inode(dir)) &&
420 !fscrypt_has_permitted_context(d_inode(dir), inode)) {
421 ext4_warning(inode->i_sb,
422 "Inconsistent encryption contexts: %lu/%lu",
423 (unsigned long) d_inode(dir)->i_ino,
424 (unsigned long) inode->i_ino);
425 dput(dir);
426 return -EPERM;
427 }
428 dput(dir);
429 /*
430 * Set up the jbd2_inode if we are opening the inode for
431 * writing and the journal is present
432 */
433 if (filp->f_mode & FMODE_WRITE) {
434 ret = ext4_inode_attach_jinode(inode);
435 if (ret < 0)
436 return ret;
437 }
438 return dquot_file_open(inode, filp);
439}
440
441/*
442 * Here we use ext4_map_blocks() to get a block mapping for a extent-based
443 * file rather than ext4_ext_walk_space() because we can introduce
444 * SEEK_DATA/SEEK_HOLE for block-mapped and extent-mapped file at the same
445 * function. When extent status tree has been fully implemented, it will
446 * track all extent status for a file and we can directly use it to
447 * retrieve the offset for SEEK_DATA/SEEK_HOLE.
448 */
449
450/*
451 * When we retrieve the offset for SEEK_DATA/SEEK_HOLE, we would need to
452 * lookup page cache to check whether or not there has some data between
453 * [startoff, endoff] because, if this range contains an unwritten extent,
454 * we determine this extent as a data or a hole according to whether the
455 * page cache has data or not.
456 */
457static int ext4_find_unwritten_pgoff(struct inode *inode,
458 int whence,
459 ext4_lblk_t end_blk,
460 loff_t *offset)
461{
462 struct pagevec pvec;
463 unsigned int blkbits;
464 pgoff_t index;
465 pgoff_t end;
466 loff_t endoff;
467 loff_t startoff;
468 loff_t lastoff;
469 int found = 0;
470
471 blkbits = inode->i_sb->s_blocksize_bits;
472 startoff = *offset;
473 lastoff = startoff;
474 endoff = (loff_t)end_blk << blkbits;
475
476 index = startoff >> PAGE_SHIFT;
477 end = endoff >> PAGE_SHIFT;
478
479 pagevec_init(&pvec, 0);
480 do {
481 int i, num;
482 unsigned long nr_pages;
483
484 num = min_t(pgoff_t, end - index, PAGEVEC_SIZE);
485 nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index,
486 (pgoff_t)num);
487 if (nr_pages == 0) {
488 if (whence == SEEK_DATA)
489 break;
490
491 BUG_ON(whence != SEEK_HOLE);
492 /*
493 * If this is the first time to go into the loop and
494 * offset is not beyond the end offset, it will be a
495 * hole at this offset
496 */
497 if (lastoff == startoff || lastoff < endoff)
498 found = 1;
499 break;
500 }
501
502 /*
503 * If this is the first time to go into the loop and
504 * offset is smaller than the first page offset, it will be a
505 * hole at this offset.
506 */
507 if (lastoff == startoff && whence == SEEK_HOLE &&
508 lastoff < page_offset(pvec.pages[0])) {
509 found = 1;
510 break;
511 }
512
513 for (i = 0; i < nr_pages; i++) {
514 struct page *page = pvec.pages[i];
515 struct buffer_head *bh, *head;
516
517 /*
518 * If the current offset is not beyond the end of given
519 * range, it will be a hole.
520 */
521 if (lastoff < endoff && whence == SEEK_HOLE &&
522 page->index > end) {
523 found = 1;
524 *offset = lastoff;
525 goto out;
526 }
527
528 lock_page(page);
529
530 if (unlikely(page->mapping != inode->i_mapping)) {
531 unlock_page(page);
532 continue;
533 }
534
535 if (!page_has_buffers(page)) {
536 unlock_page(page);
537 continue;
538 }
539
540 if (page_has_buffers(page)) {
541 lastoff = page_offset(page);
542 bh = head = page_buffers(page);
543 do {
544 if (buffer_uptodate(bh) ||
545 buffer_unwritten(bh)) {
546 if (whence == SEEK_DATA)
547 found = 1;
548 } else {
549 if (whence == SEEK_HOLE)
550 found = 1;
551 }
552 if (found) {
553 *offset = max_t(loff_t,
554 startoff, lastoff);
555 unlock_page(page);
556 goto out;
557 }
558 lastoff += bh->b_size;
559 bh = bh->b_this_page;
560 } while (bh != head);
561 }
562
563 lastoff = page_offset(page) + PAGE_SIZE;
564 unlock_page(page);
565 }
566
567 /*
568 * The no. of pages is less than our desired, that would be a
569 * hole in there.
570 */
571 if (nr_pages < num && whence == SEEK_HOLE) {
572 found = 1;
573 *offset = lastoff;
574 break;
575 }
576
577 index = pvec.pages[i - 1]->index + 1;
578 pagevec_release(&pvec);
579 } while (index <= end);
580
581out:
582 pagevec_release(&pvec);
583 return found;
584}
585
586/*
587 * ext4_seek_data() retrieves the offset for SEEK_DATA.
588 */
589static loff_t ext4_seek_data(struct file *file, loff_t offset, loff_t maxsize)
590{
591 struct inode *inode = file->f_mapping->host;
592 struct extent_status es;
593 ext4_lblk_t start, last, end;
594 loff_t dataoff, isize;
595 int blkbits;
596 int ret;
597
598 inode_lock(inode);
599
600 isize = i_size_read(inode);
601 if (offset >= isize) {
602 inode_unlock(inode);
603 return -ENXIO;
604 }
605
606 blkbits = inode->i_sb->s_blocksize_bits;
607 start = offset >> blkbits;
608 last = start;
609 end = isize >> blkbits;
610 dataoff = offset;
611
612 do {
613 ret = ext4_get_next_extent(inode, last, end - last + 1, &es);
614 if (ret <= 0) {
615 /* No extent found -> no data */
616 if (ret == 0)
617 ret = -ENXIO;
618 inode_unlock(inode);
619 return ret;
620 }
621
622 last = es.es_lblk;
623 if (last != start)
624 dataoff = (loff_t)last << blkbits;
625 if (!ext4_es_is_unwritten(&es))
626 break;
627
628 /*
629 * If there is a unwritten extent at this offset,
630 * it will be as a data or a hole according to page
631 * cache that has data or not.
632 */
633 if (ext4_find_unwritten_pgoff(inode, SEEK_DATA,
634 es.es_lblk + es.es_len, &dataoff))
635 break;
636 last += es.es_len;
637 dataoff = (loff_t)last << blkbits;
638 cond_resched();
639 } while (last <= end);
640
641 inode_unlock(inode);
642
643 if (dataoff > isize)
644 return -ENXIO;
645
646 return vfs_setpos(file, dataoff, maxsize);
647}
648
649/*
650 * ext4_seek_hole() retrieves the offset for SEEK_HOLE.
651 */
652static loff_t ext4_seek_hole(struct file *file, loff_t offset, loff_t maxsize)
653{
654 struct inode *inode = file->f_mapping->host;
655 struct extent_status es;
656 ext4_lblk_t start, last, end;
657 loff_t holeoff, isize;
658 int blkbits;
659 int ret;
660
661 inode_lock(inode);
662
663 isize = i_size_read(inode);
664 if (offset >= isize) {
665 inode_unlock(inode);
666 return -ENXIO;
667 }
668
669 blkbits = inode->i_sb->s_blocksize_bits;
670 start = offset >> blkbits;
671 last = start;
672 end = isize >> blkbits;
673 holeoff = offset;
674
675 do {
676 ret = ext4_get_next_extent(inode, last, end - last + 1, &es);
677 if (ret < 0) {
678 inode_unlock(inode);
679 return ret;
680 }
681 /* Found a hole? */
682 if (ret == 0 || es.es_lblk > last) {
683 if (last != start)
684 holeoff = (loff_t)last << blkbits;
685 break;
686 }
687 /*
688 * If there is a unwritten extent at this offset,
689 * it will be as a data or a hole according to page
690 * cache that has data or not.
691 */
692 if (ext4_es_is_unwritten(&es) &&
693 ext4_find_unwritten_pgoff(inode, SEEK_HOLE,
694 last + es.es_len, &holeoff))
695 break;
696
697 last += es.es_len;
698 holeoff = (loff_t)last << blkbits;
699 cond_resched();
700 } while (last <= end);
701
702 inode_unlock(inode);
703
704 if (holeoff > isize)
705 holeoff = isize;
706
707 return vfs_setpos(file, holeoff, maxsize);
708}
709
710/*
711 * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
712 * by calling generic_file_llseek_size() with the appropriate maxbytes
713 * value for each.
714 */
715loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
716{
717 struct inode *inode = file->f_mapping->host;
718 loff_t maxbytes;
719
720 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
721 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
722 else
723 maxbytes = inode->i_sb->s_maxbytes;
724
725 switch (whence) {
726 case SEEK_SET:
727 case SEEK_CUR:
728 case SEEK_END:
729 return generic_file_llseek_size(file, offset, whence,
730 maxbytes, i_size_read(inode));
731 case SEEK_DATA:
732 return ext4_seek_data(file, offset, maxbytes);
733 case SEEK_HOLE:
734 return ext4_seek_hole(file, offset, maxbytes);
735 }
736
737 return -EINVAL;
738}
739
740const struct file_operations ext4_file_operations = {
741 .llseek = ext4_llseek,
742 .read_iter = ext4_file_read_iter,
743 .write_iter = ext4_file_write_iter,
744 .unlocked_ioctl = ext4_ioctl,
745#ifdef CONFIG_COMPAT
746 .compat_ioctl = ext4_compat_ioctl,
747#endif
748 .mmap = ext4_file_mmap,
749 .open = ext4_file_open,
750 .release = ext4_release_file,
751 .fsync = ext4_sync_file,
752 .get_unmapped_area = thp_get_unmapped_area,
753 .splice_read = generic_file_splice_read,
754 .splice_write = iter_file_splice_write,
755 .fallocate = ext4_fallocate,
756};
757
758const struct inode_operations ext4_file_inode_operations = {
759 .setattr = ext4_setattr,
760 .getattr = ext4_getattr,
761 .listxattr = ext4_listxattr,
762 .get_acl = ext4_get_acl,
763 .set_acl = ext4_set_acl,
764 .fiemap = ext4_fiemap,
765};
766