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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
39static bool ext4_dio_supported(struct inode *inode)
40{
41 if (IS_ENABLED(CONFIG_FS_ENCRYPTION) && IS_ENCRYPTED(inode))
42 return false;
43 if (fsverity_active(inode))
44 return false;
45 if (ext4_should_journal_data(inode))
46 return false;
47 if (ext4_has_inline_data(inode))
48 return false;
49 return true;
50}
51
52static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
53{
54 ssize_t ret;
55 struct inode *inode = file_inode(iocb->ki_filp);
56
57 if (iocb->ki_flags & IOCB_NOWAIT) {
58 if (!inode_trylock_shared(inode))
59 return -EAGAIN;
60 } else {
61 inode_lock_shared(inode);
62 }
63
64 if (!ext4_dio_supported(inode)) {
65 inode_unlock_shared(inode);
66 /*
67 * Fallback to buffered I/O if the operation being performed on
68 * the inode is not supported by direct I/O. The IOCB_DIRECT
69 * flag needs to be cleared here in order to ensure that the
70 * direct I/O path within generic_file_read_iter() is not
71 * taken.
72 */
73 iocb->ki_flags &= ~IOCB_DIRECT;
74 return generic_file_read_iter(iocb, to);
75 }
76
77 ret = iomap_dio_rw(iocb, to, &ext4_iomap_ops, NULL,
78 is_sync_kiocb(iocb));
79 inode_unlock_shared(inode);
80
81 file_accessed(iocb->ki_filp);
82 return ret;
83}
84
85#ifdef CONFIG_FS_DAX
86static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
87{
88 struct inode *inode = file_inode(iocb->ki_filp);
89 ssize_t ret;
90
91 if (iocb->ki_flags & IOCB_NOWAIT) {
92 if (!inode_trylock_shared(inode))
93 return -EAGAIN;
94 } else {
95 inode_lock_shared(inode);
96 }
97 /*
98 * Recheck under inode lock - at this point we are sure it cannot
99 * change anymore
100 */
101 if (!IS_DAX(inode)) {
102 inode_unlock_shared(inode);
103 /* Fallback to buffered IO in case we cannot support DAX */
104 return generic_file_read_iter(iocb, to);
105 }
106 ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
107 inode_unlock_shared(inode);
108
109 file_accessed(iocb->ki_filp);
110 return ret;
111}
112#endif
113
114static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
115{
116 struct inode *inode = file_inode(iocb->ki_filp);
117
118 if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
119 return -EIO;
120
121 if (!iov_iter_count(to))
122 return 0; /* skip atime */
123
124#ifdef CONFIG_FS_DAX
125 if (IS_DAX(inode))
126 return ext4_dax_read_iter(iocb, to);
127#endif
128 if (iocb->ki_flags & IOCB_DIRECT)
129 return ext4_dio_read_iter(iocb, to);
130
131 return generic_file_read_iter(iocb, to);
132}
133
134/*
135 * Called when an inode is released. Note that this is different
136 * from ext4_file_open: open gets called at every open, but release
137 * gets called only when /all/ the files are closed.
138 */
139static int ext4_release_file(struct inode *inode, struct file *filp)
140{
141 if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
142 ext4_alloc_da_blocks(inode);
143 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
144 }
145 /* if we are the last writer on the inode, drop the block reservation */
146 if ((filp->f_mode & FMODE_WRITE) &&
147 (atomic_read(&inode->i_writecount) == 1) &&
148 !EXT4_I(inode)->i_reserved_data_blocks) {
149 down_write(&EXT4_I(inode)->i_data_sem);
150 ext4_discard_preallocations(inode, 0);
151 up_write(&EXT4_I(inode)->i_data_sem);
152 }
153 if (is_dx(inode) && filp->private_data)
154 ext4_htree_free_dir_info(filp->private_data);
155
156 return 0;
157}
158
159/*
160 * This tests whether the IO in question is block-aligned or not.
161 * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
162 * are converted to written only after the IO is complete. Until they are
163 * mapped, these blocks appear as holes, so dio_zero_block() will assume that
164 * it needs to zero out portions of the start and/or end block. If 2 AIO
165 * threads are at work on the same unwritten block, they must be synchronized
166 * or one thread will zero the other's data, causing corruption.
167 */
168static bool
169ext4_unaligned_io(struct inode *inode, struct iov_iter *from, loff_t pos)
170{
171 struct super_block *sb = inode->i_sb;
172 unsigned long blockmask = sb->s_blocksize - 1;
173
174 if ((pos | iov_iter_alignment(from)) & blockmask)
175 return true;
176
177 return false;
178}
179
180static bool
181ext4_extending_io(struct inode *inode, loff_t offset, size_t len)
182{
183 if (offset + len > i_size_read(inode) ||
184 offset + len > EXT4_I(inode)->i_disksize)
185 return true;
186 return false;
187}
188
189/* Is IO overwriting allocated and initialized blocks? */
190static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len)
191{
192 struct ext4_map_blocks map;
193 unsigned int blkbits = inode->i_blkbits;
194 int err, blklen;
195
196 if (pos + len > i_size_read(inode))
197 return false;
198
199 map.m_lblk = pos >> blkbits;
200 map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
201 blklen = map.m_len;
202
203 err = ext4_map_blocks(NULL, inode, &map, 0);
204 /*
205 * 'err==len' means that all of the blocks have been preallocated,
206 * regardless of whether they have been initialized or not. To exclude
207 * unwritten extents, we need to check m_flags.
208 */
209 return err == blklen && (map.m_flags & EXT4_MAP_MAPPED);
210}
211
212static ssize_t ext4_generic_write_checks(struct kiocb *iocb,
213 struct iov_iter *from)
214{
215 struct inode *inode = file_inode(iocb->ki_filp);
216 ssize_t ret;
217
218 if (unlikely(IS_IMMUTABLE(inode)))
219 return -EPERM;
220
221 ret = generic_write_checks(iocb, from);
222 if (ret <= 0)
223 return ret;
224
225 /*
226 * If we have encountered a bitmap-format file, the size limit
227 * is smaller than s_maxbytes, which is for extent-mapped files.
228 */
229 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
230 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
231
232 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
233 return -EFBIG;
234 iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
235 }
236
237 return iov_iter_count(from);
238}
239
240static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
241{
242 ssize_t ret, count;
243
244 count = ext4_generic_write_checks(iocb, from);
245 if (count <= 0)
246 return count;
247
248 ret = file_modified(iocb->ki_filp);
249 if (ret)
250 return ret;
251 return count;
252}
253
254static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
255 struct iov_iter *from)
256{
257 ssize_t ret;
258 struct inode *inode = file_inode(iocb->ki_filp);
259
260 if (iocb->ki_flags & IOCB_NOWAIT)
261 return -EOPNOTSUPP;
262
263 inode_lock(inode);
264 ret = ext4_write_checks(iocb, from);
265 if (ret <= 0)
266 goto out;
267
268 current->backing_dev_info = inode_to_bdi(inode);
269 ret = generic_perform_write(iocb->ki_filp, from, iocb->ki_pos);
270 current->backing_dev_info = NULL;
271
272out:
273 inode_unlock(inode);
274 if (likely(ret > 0)) {
275 iocb->ki_pos += ret;
276 ret = generic_write_sync(iocb, ret);
277 }
278
279 return ret;
280}
281
282static ssize_t ext4_handle_inode_extension(struct inode *inode, loff_t offset,
283 ssize_t written, size_t count)
284{
285 handle_t *handle;
286 bool truncate = false;
287 u8 blkbits = inode->i_blkbits;
288 ext4_lblk_t written_blk, end_blk;
289 int ret;
290
291 /*
292 * Note that EXT4_I(inode)->i_disksize can get extended up to
293 * inode->i_size while the I/O was running due to writeback of delalloc
294 * blocks. But, the code in ext4_iomap_alloc() is careful to use
295 * zeroed/unwritten extents if this is possible; thus we won't leave
296 * uninitialized blocks in a file even if we didn't succeed in writing
297 * as much as we intended.
298 */
299 WARN_ON_ONCE(i_size_read(inode) < EXT4_I(inode)->i_disksize);
300 if (offset + count <= EXT4_I(inode)->i_disksize) {
301 /*
302 * We need to ensure that the inode is removed from the orphan
303 * list if it has been added prematurely, due to writeback of
304 * delalloc blocks.
305 */
306 if (!list_empty(&EXT4_I(inode)->i_orphan) && inode->i_nlink) {
307 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
308
309 if (IS_ERR(handle)) {
310 ext4_orphan_del(NULL, inode);
311 return PTR_ERR(handle);
312 }
313
314 ext4_orphan_del(handle, inode);
315 ext4_journal_stop(handle);
316 }
317
318 return written;
319 }
320
321 if (written < 0)
322 goto truncate;
323
324 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
325 if (IS_ERR(handle)) {
326 written = PTR_ERR(handle);
327 goto truncate;
328 }
329
330 if (ext4_update_inode_size(inode, offset + written)) {
331 ret = ext4_mark_inode_dirty(handle, inode);
332 if (unlikely(ret)) {
333 written = ret;
334 ext4_journal_stop(handle);
335 goto truncate;
336 }
337 }
338
339 /*
340 * We may need to truncate allocated but not written blocks beyond EOF.
341 */
342 written_blk = ALIGN(offset + written, 1 << blkbits);
343 end_blk = ALIGN(offset + count, 1 << blkbits);
344 if (written_blk < end_blk && ext4_can_truncate(inode))
345 truncate = true;
346
347 /*
348 * Remove the inode from the orphan list if it has been extended and
349 * everything went OK.
350 */
351 if (!truncate && inode->i_nlink)
352 ext4_orphan_del(handle, inode);
353 ext4_journal_stop(handle);
354
355 if (truncate) {
356truncate:
357 ext4_truncate_failed_write(inode);
358 /*
359 * If the truncate operation failed early, then the inode may
360 * still be on the orphan list. In that case, we need to try
361 * remove the inode from the in-memory linked list.
362 */
363 if (inode->i_nlink)
364 ext4_orphan_del(NULL, inode);
365 }
366
367 return written;
368}
369
370static int ext4_dio_write_end_io(struct kiocb *iocb, ssize_t size,
371 int error, unsigned int flags)
372{
373 loff_t offset = iocb->ki_pos;
374 struct inode *inode = file_inode(iocb->ki_filp);
375
376 if (error)
377 return error;
378
379 if (size && flags & IOMAP_DIO_UNWRITTEN)
380 return ext4_convert_unwritten_extents(NULL, inode,
381 offset, size);
382
383 return 0;
384}
385
386static const struct iomap_dio_ops ext4_dio_write_ops = {
387 .end_io = ext4_dio_write_end_io,
388};
389
390/*
391 * The intention here is to start with shared lock acquired then see if any
392 * condition requires an exclusive inode lock. If yes, then we restart the
393 * whole operation by releasing the shared lock and acquiring exclusive lock.
394 *
395 * - For unaligned_io we never take shared lock as it may cause data corruption
396 * when two unaligned IO tries to modify the same block e.g. while zeroing.
397 *
398 * - For extending writes case we don't take the shared lock, since it requires
399 * updating inode i_disksize and/or orphan handling with exclusive lock.
400 *
401 * - shared locking will only be true mostly with overwrites. Otherwise we will
402 * switch to exclusive i_rwsem lock.
403 */
404static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from,
405 bool *ilock_shared, bool *extend)
406{
407 struct file *file = iocb->ki_filp;
408 struct inode *inode = file_inode(file);
409 loff_t offset;
410 size_t count;
411 ssize_t ret;
412
413restart:
414 ret = ext4_generic_write_checks(iocb, from);
415 if (ret <= 0)
416 goto out;
417
418 offset = iocb->ki_pos;
419 count = ret;
420 if (ext4_extending_io(inode, offset, count))
421 *extend = true;
422 /*
423 * Determine whether the IO operation will overwrite allocated
424 * and initialized blocks.
425 * We need exclusive i_rwsem for changing security info
426 * in file_modified().
427 */
428 if (*ilock_shared && (!IS_NOSEC(inode) || *extend ||
429 !ext4_overwrite_io(inode, offset, count))) {
430 if (iocb->ki_flags & IOCB_NOWAIT) {
431 ret = -EAGAIN;
432 goto out;
433 }
434 inode_unlock_shared(inode);
435 *ilock_shared = false;
436 inode_lock(inode);
437 goto restart;
438 }
439
440 ret = file_modified(file);
441 if (ret < 0)
442 goto out;
443
444 return count;
445out:
446 if (*ilock_shared)
447 inode_unlock_shared(inode);
448 else
449 inode_unlock(inode);
450 return ret;
451}
452
453static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
454{
455 ssize_t ret;
456 handle_t *handle;
457 struct inode *inode = file_inode(iocb->ki_filp);
458 loff_t offset = iocb->ki_pos;
459 size_t count = iov_iter_count(from);
460 const struct iomap_ops *iomap_ops = &ext4_iomap_ops;
461 bool extend = false, unaligned_io = false;
462 bool ilock_shared = true;
463
464 /*
465 * We initially start with shared inode lock unless it is
466 * unaligned IO which needs exclusive lock anyways.
467 */
468 if (ext4_unaligned_io(inode, from, offset)) {
469 unaligned_io = true;
470 ilock_shared = false;
471 }
472 /*
473 * Quick check here without any i_rwsem lock to see if it is extending
474 * IO. A more reliable check is done in ext4_dio_write_checks() with
475 * proper locking in place.
476 */
477 if (offset + count > i_size_read(inode))
478 ilock_shared = false;
479
480 if (iocb->ki_flags & IOCB_NOWAIT) {
481 if (ilock_shared) {
482 if (!inode_trylock_shared(inode))
483 return -EAGAIN;
484 } else {
485 if (!inode_trylock(inode))
486 return -EAGAIN;
487 }
488 } else {
489 if (ilock_shared)
490 inode_lock_shared(inode);
491 else
492 inode_lock(inode);
493 }
494
495 /* Fallback to buffered I/O if the inode does not support direct I/O. */
496 if (!ext4_dio_supported(inode)) {
497 if (ilock_shared)
498 inode_unlock_shared(inode);
499 else
500 inode_unlock(inode);
501 return ext4_buffered_write_iter(iocb, from);
502 }
503
504 ret = ext4_dio_write_checks(iocb, from, &ilock_shared, &extend);
505 if (ret <= 0)
506 return ret;
507
508 /* if we're going to block and IOCB_NOWAIT is set, return -EAGAIN */
509 if ((iocb->ki_flags & IOCB_NOWAIT) && (unaligned_io || extend)) {
510 ret = -EAGAIN;
511 goto out;
512 }
513
514 offset = iocb->ki_pos;
515 count = ret;
516
517 /*
518 * Unaligned direct IO must be serialized among each other as zeroing
519 * of partial blocks of two competing unaligned IOs can result in data
520 * corruption.
521 *
522 * So we make sure we don't allow any unaligned IO in flight.
523 * For IOs where we need not wait (like unaligned non-AIO DIO),
524 * below inode_dio_wait() may anyway become a no-op, since we start
525 * with exclusive lock.
526 */
527 if (unaligned_io)
528 inode_dio_wait(inode);
529
530 if (extend) {
531 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
532 if (IS_ERR(handle)) {
533 ret = PTR_ERR(handle);
534 goto out;
535 }
536
537 ret = ext4_orphan_add(handle, inode);
538 if (ret) {
539 ext4_journal_stop(handle);
540 goto out;
541 }
542
543 ext4_journal_stop(handle);
544 }
545
546 if (ilock_shared)
547 iomap_ops = &ext4_iomap_overwrite_ops;
548 ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops,
549 is_sync_kiocb(iocb) || unaligned_io || extend);
550 if (ret == -ENOTBLK)
551 ret = 0;
552
553 if (extend)
554 ret = ext4_handle_inode_extension(inode, offset, ret, count);
555
556out:
557 if (ilock_shared)
558 inode_unlock_shared(inode);
559 else
560 inode_unlock(inode);
561
562 if (ret >= 0 && iov_iter_count(from)) {
563 ssize_t err;
564 loff_t endbyte;
565
566 offset = iocb->ki_pos;
567 err = ext4_buffered_write_iter(iocb, from);
568 if (err < 0)
569 return err;
570
571 /*
572 * We need to ensure that the pages within the page cache for
573 * the range covered by this I/O are written to disk and
574 * invalidated. This is in attempt to preserve the expected
575 * direct I/O semantics in the case we fallback to buffered I/O
576 * to complete off the I/O request.
577 */
578 ret += err;
579 endbyte = offset + err - 1;
580 err = filemap_write_and_wait_range(iocb->ki_filp->f_mapping,
581 offset, endbyte);
582 if (!err)
583 invalidate_mapping_pages(iocb->ki_filp->f_mapping,
584 offset >> PAGE_SHIFT,
585 endbyte >> PAGE_SHIFT);
586 }
587
588 return ret;
589}
590
591#ifdef CONFIG_FS_DAX
592static ssize_t
593ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
594{
595 ssize_t ret;
596 size_t count;
597 loff_t offset;
598 handle_t *handle;
599 bool extend = false;
600 struct inode *inode = file_inode(iocb->ki_filp);
601
602 if (iocb->ki_flags & IOCB_NOWAIT) {
603 if (!inode_trylock(inode))
604 return -EAGAIN;
605 } else {
606 inode_lock(inode);
607 }
608
609 ret = ext4_write_checks(iocb, from);
610 if (ret <= 0)
611 goto out;
612
613 offset = iocb->ki_pos;
614 count = iov_iter_count(from);
615
616 if (offset + count > EXT4_I(inode)->i_disksize) {
617 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
618 if (IS_ERR(handle)) {
619 ret = PTR_ERR(handle);
620 goto out;
621 }
622
623 ret = ext4_orphan_add(handle, inode);
624 if (ret) {
625 ext4_journal_stop(handle);
626 goto out;
627 }
628
629 extend = true;
630 ext4_journal_stop(handle);
631 }
632
633 ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
634
635 if (extend)
636 ret = ext4_handle_inode_extension(inode, offset, ret, count);
637out:
638 inode_unlock(inode);
639 if (ret > 0)
640 ret = generic_write_sync(iocb, ret);
641 return ret;
642}
643#endif
644
645static ssize_t
646ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
647{
648 struct inode *inode = file_inode(iocb->ki_filp);
649
650 if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
651 return -EIO;
652
653#ifdef CONFIG_FS_DAX
654 if (IS_DAX(inode))
655 return ext4_dax_write_iter(iocb, from);
656#endif
657 if (iocb->ki_flags & IOCB_DIRECT)
658 return ext4_dio_write_iter(iocb, from);
659
660 return ext4_buffered_write_iter(iocb, from);
661}
662
663#ifdef CONFIG_FS_DAX
664static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf,
665 enum page_entry_size pe_size)
666{
667 int error = 0;
668 vm_fault_t result;
669 int retries = 0;
670 handle_t *handle = NULL;
671 struct inode *inode = file_inode(vmf->vma->vm_file);
672 struct super_block *sb = inode->i_sb;
673
674 /*
675 * We have to distinguish real writes from writes which will result in a
676 * COW page; COW writes should *not* poke the journal (the file will not
677 * be changed). Doing so would cause unintended failures when mounted
678 * read-only.
679 *
680 * We check for VM_SHARED rather than vmf->cow_page since the latter is
681 * unset for pe_size != PE_SIZE_PTE (i.e. only in do_cow_fault); for
682 * other sizes, dax_iomap_fault will handle splitting / fallback so that
683 * we eventually come back with a COW page.
684 */
685 bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
686 (vmf->vma->vm_flags & VM_SHARED);
687 pfn_t pfn;
688
689 if (write) {
690 sb_start_pagefault(sb);
691 file_update_time(vmf->vma->vm_file);
692 down_read(&EXT4_I(inode)->i_mmap_sem);
693retry:
694 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
695 EXT4_DATA_TRANS_BLOCKS(sb));
696 if (IS_ERR(handle)) {
697 up_read(&EXT4_I(inode)->i_mmap_sem);
698 sb_end_pagefault(sb);
699 return VM_FAULT_SIGBUS;
700 }
701 } else {
702 down_read(&EXT4_I(inode)->i_mmap_sem);
703 }
704 result = dax_iomap_fault(vmf, pe_size, &pfn, &error, &ext4_iomap_ops);
705 if (write) {
706 ext4_journal_stop(handle);
707
708 if ((result & VM_FAULT_ERROR) && error == -ENOSPC &&
709 ext4_should_retry_alloc(sb, &retries))
710 goto retry;
711 /* Handling synchronous page fault? */
712 if (result & VM_FAULT_NEEDDSYNC)
713 result = dax_finish_sync_fault(vmf, pe_size, pfn);
714 up_read(&EXT4_I(inode)->i_mmap_sem);
715 sb_end_pagefault(sb);
716 } else {
717 up_read(&EXT4_I(inode)->i_mmap_sem);
718 }
719
720 return result;
721}
722
723static vm_fault_t ext4_dax_fault(struct vm_fault *vmf)
724{
725 return ext4_dax_huge_fault(vmf, PE_SIZE_PTE);
726}
727
728static const struct vm_operations_struct ext4_dax_vm_ops = {
729 .fault = ext4_dax_fault,
730 .huge_fault = ext4_dax_huge_fault,
731 .page_mkwrite = ext4_dax_fault,
732 .pfn_mkwrite = ext4_dax_fault,
733};
734#else
735#define ext4_dax_vm_ops ext4_file_vm_ops
736#endif
737
738static const struct vm_operations_struct ext4_file_vm_ops = {
739 .fault = ext4_filemap_fault,
740 .map_pages = filemap_map_pages,
741 .page_mkwrite = ext4_page_mkwrite,
742};
743
744static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
745{
746 struct inode *inode = file->f_mapping->host;
747 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
748 struct dax_device *dax_dev = sbi->s_daxdev;
749
750 if (unlikely(ext4_forced_shutdown(sbi)))
751 return -EIO;
752
753 /*
754 * We don't support synchronous mappings for non-DAX files and
755 * for DAX files if underneath dax_device is not synchronous.
756 */
757 if (!daxdev_mapping_supported(vma, dax_dev))
758 return -EOPNOTSUPP;
759
760 file_accessed(file);
761 if (IS_DAX(file_inode(file))) {
762 vma->vm_ops = &ext4_dax_vm_ops;
763 vma->vm_flags |= VM_HUGEPAGE;
764 } else {
765 vma->vm_ops = &ext4_file_vm_ops;
766 }
767 return 0;
768}
769
770static int ext4_sample_last_mounted(struct super_block *sb,
771 struct vfsmount *mnt)
772{
773 struct ext4_sb_info *sbi = EXT4_SB(sb);
774 struct path path;
775 char buf[64], *cp;
776 handle_t *handle;
777 int err;
778
779 if (likely(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED))
780 return 0;
781
782 if (sb_rdonly(sb) || !sb_start_intwrite_trylock(sb))
783 return 0;
784
785 sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
786 /*
787 * Sample where the filesystem has been mounted and
788 * store it in the superblock for sysadmin convenience
789 * when trying to sort through large numbers of block
790 * devices or filesystem images.
791 */
792 memset(buf, 0, sizeof(buf));
793 path.mnt = mnt;
794 path.dentry = mnt->mnt_root;
795 cp = d_path(&path, buf, sizeof(buf));
796 err = 0;
797 if (IS_ERR(cp))
798 goto out;
799
800 handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
801 err = PTR_ERR(handle);
802 if (IS_ERR(handle))
803 goto out;
804 BUFFER_TRACE(sbi->s_sbh, "get_write_access");
805 err = ext4_journal_get_write_access(handle, sbi->s_sbh);
806 if (err)
807 goto out_journal;
808 strlcpy(sbi->s_es->s_last_mounted, cp,
809 sizeof(sbi->s_es->s_last_mounted));
810 ext4_handle_dirty_super(handle, sb);
811out_journal:
812 ext4_journal_stop(handle);
813out:
814 sb_end_intwrite(sb);
815 return err;
816}
817
818static int ext4_file_open(struct inode *inode, struct file *filp)
819{
820 int ret;
821
822 if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
823 return -EIO;
824
825 ret = ext4_sample_last_mounted(inode->i_sb, filp->f_path.mnt);
826 if (ret)
827 return ret;
828
829 ret = fscrypt_file_open(inode, filp);
830 if (ret)
831 return ret;
832
833 ret = fsverity_file_open(inode, filp);
834 if (ret)
835 return ret;
836
837 /*
838 * Set up the jbd2_inode if we are opening the inode for
839 * writing and the journal is present
840 */
841 if (filp->f_mode & FMODE_WRITE) {
842 ret = ext4_inode_attach_jinode(inode);
843 if (ret < 0)
844 return ret;
845 }
846
847 filp->f_mode |= FMODE_NOWAIT;
848 return dquot_file_open(inode, filp);
849}
850
851/*
852 * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
853 * by calling generic_file_llseek_size() with the appropriate maxbytes
854 * value for each.
855 */
856loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
857{
858 struct inode *inode = file->f_mapping->host;
859 loff_t maxbytes;
860
861 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
862 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
863 else
864 maxbytes = inode->i_sb->s_maxbytes;
865
866 switch (whence) {
867 default:
868 return generic_file_llseek_size(file, offset, whence,
869 maxbytes, i_size_read(inode));
870 case SEEK_HOLE:
871 inode_lock_shared(inode);
872 offset = iomap_seek_hole(inode, offset,
873 &ext4_iomap_report_ops);
874 inode_unlock_shared(inode);
875 break;
876 case SEEK_DATA:
877 inode_lock_shared(inode);
878 offset = iomap_seek_data(inode, offset,
879 &ext4_iomap_report_ops);
880 inode_unlock_shared(inode);
881 break;
882 }
883
884 if (offset < 0)
885 return offset;
886 return vfs_setpos(file, offset, maxbytes);
887}
888
889const struct file_operations ext4_file_operations = {
890 .llseek = ext4_llseek,
891 .read_iter = ext4_file_read_iter,
892 .write_iter = ext4_file_write_iter,
893 .iopoll = iomap_dio_iopoll,
894 .unlocked_ioctl = ext4_ioctl,
895#ifdef CONFIG_COMPAT
896 .compat_ioctl = ext4_compat_ioctl,
897#endif
898 .mmap = ext4_file_mmap,
899 .mmap_supported_flags = MAP_SYNC,
900 .open = ext4_file_open,
901 .release = ext4_release_file,
902 .fsync = ext4_sync_file,
903 .get_unmapped_area = thp_get_unmapped_area,
904 .splice_read = generic_file_splice_read,
905 .splice_write = iter_file_splice_write,
906 .fallocate = ext4_fallocate,
907};
908
909const struct inode_operations ext4_file_inode_operations = {
910 .setattr = ext4_setattr,
911 .getattr = ext4_file_getattr,
912 .listxattr = ext4_listxattr,
913 .get_acl = ext4_get_acl,
914 .set_acl = ext4_set_acl,
915 .fiemap = ext4_fiemap,
916};
917
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(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
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(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, 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 */
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(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, 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(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
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(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(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, ret);
306}
307
308static 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 */
337static 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
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(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
399static 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 */
421static 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
432restart:
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;
490out:
491 if (*ilock_shared)
492 inode_unlock_shared(inode);
493 else
494 inode_unlock(inode);
495 return ret;
496}
497
498static 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
592out:
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
628static ssize_t
629ext4_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 }
675out:
676 inode_unlock(inode);
677 if (ret > 0)
678 ret = generic_write_sync(iocb, ret);
679 return ret;
680}
681#endif
682
683static ssize_t
684ext4_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
702static 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);
731retry:
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
761static vm_fault_t ext4_dax_fault(struct vm_fault *vmf)
762{
763 return ext4_dax_huge_fault(vmf, 0);
764}
765
766static 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
776static 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
782static 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
807static 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 strncpy(sbi->s_es->s_last_mounted, cp,
848 sizeof(sbi->s_es->s_last_mounted));
849 ext4_superblock_csum_set(sb);
850 unlock_buffer(sbi->s_sbh);
851 ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
852out_journal:
853 ext4_journal_stop(handle);
854out:
855 sb_end_intwrite(sb);
856 return err;
857}
858
859static int ext4_file_open(struct inode *inode, struct file *filp)
860{
861 int ret;
862
863 if (unlikely(ext4_forced_shutdown(inode->i_sb)))
864 return -EIO;
865
866 ret = ext4_sample_last_mounted(inode->i_sb, filp->f_path.mnt);
867 if (ret)
868 return ret;
869
870 ret = fscrypt_file_open(inode, filp);
871 if (ret)
872 return ret;
873
874 ret = fsverity_file_open(inode, filp);
875 if (ret)
876 return ret;
877
878 /*
879 * Set up the jbd2_inode if we are opening the inode for
880 * writing and the journal is present
881 */
882 if (filp->f_mode & FMODE_WRITE) {
883 ret = ext4_inode_attach_jinode(inode);
884 if (ret < 0)
885 return ret;
886 }
887
888 filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC |
889 FMODE_DIO_PARALLEL_WRITE;
890 return dquot_file_open(inode, filp);
891}
892
893/*
894 * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
895 * by calling generic_file_llseek_size() with the appropriate maxbytes
896 * value for each.
897 */
898loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
899{
900 struct inode *inode = file->f_mapping->host;
901 loff_t maxbytes;
902
903 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
904 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
905 else
906 maxbytes = inode->i_sb->s_maxbytes;
907
908 switch (whence) {
909 default:
910 return generic_file_llseek_size(file, offset, whence,
911 maxbytes, i_size_read(inode));
912 case SEEK_HOLE:
913 inode_lock_shared(inode);
914 offset = iomap_seek_hole(inode, offset,
915 &ext4_iomap_report_ops);
916 inode_unlock_shared(inode);
917 break;
918 case SEEK_DATA:
919 inode_lock_shared(inode);
920 offset = iomap_seek_data(inode, offset,
921 &ext4_iomap_report_ops);
922 inode_unlock_shared(inode);
923 break;
924 }
925
926 if (offset < 0)
927 return offset;
928 return vfs_setpos(file, offset, maxbytes);
929}
930
931const struct file_operations ext4_file_operations = {
932 .llseek = ext4_llseek,
933 .read_iter = ext4_file_read_iter,
934 .write_iter = ext4_file_write_iter,
935 .iopoll = iocb_bio_iopoll,
936 .unlocked_ioctl = ext4_ioctl,
937#ifdef CONFIG_COMPAT
938 .compat_ioctl = ext4_compat_ioctl,
939#endif
940 .mmap = ext4_file_mmap,
941 .mmap_supported_flags = MAP_SYNC,
942 .open = ext4_file_open,
943 .release = ext4_release_file,
944 .fsync = ext4_sync_file,
945 .get_unmapped_area = thp_get_unmapped_area,
946 .splice_read = ext4_file_splice_read,
947 .splice_write = iter_file_splice_write,
948 .fallocate = ext4_fallocate,
949};
950
951const struct inode_operations ext4_file_inode_operations = {
952 .setattr = ext4_setattr,
953 .getattr = ext4_file_getattr,
954 .listxattr = ext4_listxattr,
955 .get_inode_acl = ext4_get_acl,
956 .set_acl = ext4_set_acl,
957 .fiemap = ext4_fiemap,
958 .fileattr_get = ext4_fileattr_get,
959 .fileattr_set = ext4_fileattr_set,
960};
961