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 */
ext4_should_use_dio(struct kiocb * iocb,struct iov_iter * iter)55 static bool ext4_should_use_dio(struct kiocb *iocb, struct iov_iter *iter)
56 {
57 struct inode *inode = file_inode(iocb->ki_filp);
58 u32 dio_align = ext4_dio_alignment(inode);
59
60 if (dio_align == 0)
61 return false;
62
63 if (dio_align == 1)
64 return true;
65
66 return IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(iter), dio_align);
67 }
68
ext4_dio_read_iter(struct kiocb * iocb,struct iov_iter * to)69 static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
70 {
71 ssize_t ret;
72 struct inode *inode = file_inode(iocb->ki_filp);
73
74 if (iocb->ki_flags & IOCB_NOWAIT) {
75 if (!inode_trylock_shared(inode))
76 return -EAGAIN;
77 } else {
78 inode_lock_shared(inode);
79 }
80
81 if (!ext4_should_use_dio(iocb, to)) {
82 inode_unlock_shared(inode);
83 /*
84 * Fallback to buffered I/O if the operation being performed on
85 * the inode is not supported by direct I/O. The IOCB_DIRECT
86 * flag needs to be cleared here in order to ensure that the
87 * direct I/O path within generic_file_read_iter() is not
88 * taken.
89 */
90 iocb->ki_flags &= ~IOCB_DIRECT;
91 return generic_file_read_iter(iocb, to);
92 }
93
94 ret = iomap_dio_rw(iocb, to, &ext4_iomap_ops, NULL, 0, NULL, 0);
95 inode_unlock_shared(inode);
96
97 file_accessed(iocb->ki_filp);
98 return ret;
99 }
100
101 #ifdef CONFIG_FS_DAX
ext4_dax_read_iter(struct kiocb * iocb,struct iov_iter * to)102 static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
103 {
104 struct inode *inode = file_inode(iocb->ki_filp);
105 ssize_t ret;
106
107 if (iocb->ki_flags & IOCB_NOWAIT) {
108 if (!inode_trylock_shared(inode))
109 return -EAGAIN;
110 } else {
111 inode_lock_shared(inode);
112 }
113 /*
114 * Recheck under inode lock - at this point we are sure it cannot
115 * change anymore
116 */
117 if (!IS_DAX(inode)) {
118 inode_unlock_shared(inode);
119 /* Fallback to buffered IO in case we cannot support DAX */
120 return generic_file_read_iter(iocb, to);
121 }
122 ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
123 inode_unlock_shared(inode);
124
125 file_accessed(iocb->ki_filp);
126 return ret;
127 }
128 #endif
129
ext4_file_read_iter(struct kiocb * iocb,struct iov_iter * to)130 static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
131 {
132 struct inode *inode = file_inode(iocb->ki_filp);
133
134 if (unlikely(ext4_forced_shutdown(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 */
ext4_release_file(struct inode * inode,struct file * filp)155 static 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 */
184 static bool
ext4_unaligned_io(struct inode * inode,struct iov_iter * from,loff_t pos)185 ext4_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
196 static bool
ext4_extending_io(struct inode * inode,loff_t offset,size_t len)197 ext4_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? */
ext4_overwrite_io(struct inode * inode,loff_t pos,loff_t len)206 static 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
ext4_generic_write_checks(struct kiocb * iocb,struct iov_iter * from)228 static 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
ext4_write_checks(struct kiocb * iocb,struct iov_iter * from)256 static 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
ext4_buffered_write_iter(struct kiocb * iocb,struct iov_iter * from)270 static 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
288 out:
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
ext4_handle_inode_extension(struct inode * inode,loff_t offset,ssize_t count)298 static ssize_t ext4_handle_inode_extension(struct inode *inode, loff_t offset,
299 ssize_t count)
300 {
301 handle_t *handle;
302
303 lockdep_assert_held_write(&inode->i_rwsem);
304 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
305 if (IS_ERR(handle))
306 return PTR_ERR(handle);
307
308 if (ext4_update_inode_size(inode, offset + count)) {
309 int ret = ext4_mark_inode_dirty(handle, inode);
310 if (unlikely(ret)) {
311 ext4_journal_stop(handle);
312 return ret;
313 }
314 }
315
316 if (inode->i_nlink)
317 ext4_orphan_del(handle, inode);
318 ext4_journal_stop(handle);
319
320 return count;
321 }
322
323 /*
324 * Clean up the inode after DIO or DAX extending write has completed and the
325 * inode size has been updated using ext4_handle_inode_extension().
326 */
ext4_inode_extension_cleanup(struct inode * inode,ssize_t count)327 static void ext4_inode_extension_cleanup(struct inode *inode, ssize_t count)
328 {
329 lockdep_assert_held_write(&inode->i_rwsem);
330 if (count < 0) {
331 ext4_truncate_failed_write(inode);
332 /*
333 * If the truncate operation failed early, then the inode may
334 * still be on the orphan list. In that case, we need to try
335 * remove the inode from the in-memory linked list.
336 */
337 if (inode->i_nlink)
338 ext4_orphan_del(NULL, inode);
339 return;
340 }
341 /*
342 * If i_disksize got extended either due to writeback of delalloc
343 * blocks or extending truncate while the DIO was running we could fail
344 * to cleanup the orphan list in ext4_handle_inode_extension(). Do it
345 * now.
346 */
347 if (!list_empty(&EXT4_I(inode)->i_orphan) && inode->i_nlink) {
348 handle_t *handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
349
350 if (IS_ERR(handle)) {
351 /*
352 * The write has successfully completed. Not much to
353 * do with the error here so just cleanup the orphan
354 * list and hope for the best.
355 */
356 ext4_orphan_del(NULL, inode);
357 return;
358 }
359 ext4_orphan_del(handle, inode);
360 ext4_journal_stop(handle);
361 }
362 }
363
ext4_dio_write_end_io(struct kiocb * iocb,ssize_t size,int error,unsigned int flags)364 static int ext4_dio_write_end_io(struct kiocb *iocb, ssize_t size,
365 int error, unsigned int flags)
366 {
367 loff_t pos = iocb->ki_pos;
368 struct inode *inode = file_inode(iocb->ki_filp);
369
370 if (!error && size && flags & IOMAP_DIO_UNWRITTEN)
371 error = ext4_convert_unwritten_extents(NULL, inode, pos, size);
372 if (error)
373 return error;
374 /*
375 * Note that EXT4_I(inode)->i_disksize can get extended up to
376 * inode->i_size while the I/O was running due to writeback of delalloc
377 * blocks. But the code in ext4_iomap_alloc() is careful to use
378 * zeroed/unwritten extents if this is possible; thus we won't leave
379 * uninitialized blocks in a file even if we didn't succeed in writing
380 * as much as we intended. Also we can race with truncate or write
381 * expanding the file so we have to be a bit careful here.
382 */
383 if (pos + size <= READ_ONCE(EXT4_I(inode)->i_disksize) &&
384 pos + size <= i_size_read(inode))
385 return size;
386 return ext4_handle_inode_extension(inode, pos, size);
387 }
388
389 static const struct iomap_dio_ops ext4_dio_write_ops = {
390 .end_io = ext4_dio_write_end_io,
391 };
392
393 /*
394 * The intention here is to start with shared lock acquired then see if any
395 * condition requires an exclusive inode lock. If yes, then we restart the
396 * whole operation by releasing the shared lock and acquiring exclusive lock.
397 *
398 * - For unaligned_io we never take shared lock as it may cause data corruption
399 * when two unaligned IO tries to modify the same block e.g. while zeroing.
400 *
401 * - For extending writes case we don't take the shared lock, since it requires
402 * updating inode i_disksize and/or orphan handling with exclusive lock.
403 *
404 * - shared locking will only be true mostly with overwrites. Otherwise we will
405 * switch to exclusive i_rwsem lock.
406 */
ext4_dio_write_checks(struct kiocb * iocb,struct iov_iter * from,bool * ilock_shared,bool * extend)407 static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from,
408 bool *ilock_shared, bool *extend)
409 {
410 struct file *file = iocb->ki_filp;
411 struct inode *inode = file_inode(file);
412 loff_t offset;
413 size_t count;
414 ssize_t ret;
415
416 restart:
417 ret = ext4_generic_write_checks(iocb, from);
418 if (ret <= 0)
419 goto out;
420
421 offset = iocb->ki_pos;
422 count = ret;
423 if (ext4_extending_io(inode, offset, count))
424 *extend = true;
425 /*
426 * Determine whether the IO operation will overwrite allocated
427 * and initialized blocks.
428 * We need exclusive i_rwsem for changing security info
429 * in file_modified().
430 */
431 if (*ilock_shared && (!IS_NOSEC(inode) || *extend ||
432 !ext4_overwrite_io(inode, offset, count))) {
433 if (iocb->ki_flags & IOCB_NOWAIT) {
434 ret = -EAGAIN;
435 goto out;
436 }
437 inode_unlock_shared(inode);
438 *ilock_shared = false;
439 inode_lock(inode);
440 goto restart;
441 }
442
443 ret = file_modified(file);
444 if (ret < 0)
445 goto out;
446
447 return count;
448 out:
449 if (*ilock_shared)
450 inode_unlock_shared(inode);
451 else
452 inode_unlock(inode);
453 return ret;
454 }
455
ext4_dio_write_iter(struct kiocb * iocb,struct iov_iter * from)456 static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
457 {
458 ssize_t ret;
459 handle_t *handle;
460 struct inode *inode = file_inode(iocb->ki_filp);
461 loff_t offset = iocb->ki_pos;
462 size_t count = iov_iter_count(from);
463 const struct iomap_ops *iomap_ops = &ext4_iomap_ops;
464 bool extend = false, unaligned_io = false;
465 bool ilock_shared = true;
466
467 /*
468 * We initially start with shared inode lock unless it is
469 * unaligned IO which needs exclusive lock anyways.
470 */
471 if (ext4_unaligned_io(inode, from, offset)) {
472 unaligned_io = true;
473 ilock_shared = false;
474 }
475 /*
476 * Quick check here without any i_rwsem lock to see if it is extending
477 * IO. A more reliable check is done in ext4_dio_write_checks() with
478 * proper locking in place.
479 */
480 if (offset + count > i_size_read(inode))
481 ilock_shared = false;
482
483 if (iocb->ki_flags & IOCB_NOWAIT) {
484 if (ilock_shared) {
485 if (!inode_trylock_shared(inode))
486 return -EAGAIN;
487 } else {
488 if (!inode_trylock(inode))
489 return -EAGAIN;
490 }
491 } else {
492 if (ilock_shared)
493 inode_lock_shared(inode);
494 else
495 inode_lock(inode);
496 }
497
498 /* Fallback to buffered I/O if the inode does not support direct I/O. */
499 if (!ext4_should_use_dio(iocb, from)) {
500 if (ilock_shared)
501 inode_unlock_shared(inode);
502 else
503 inode_unlock(inode);
504 return ext4_buffered_write_iter(iocb, from);
505 }
506
507 ret = ext4_dio_write_checks(iocb, from, &ilock_shared, &extend);
508 if (ret <= 0)
509 return ret;
510
511 /* if we're going to block and IOCB_NOWAIT is set, return -EAGAIN */
512 if ((iocb->ki_flags & IOCB_NOWAIT) && (unaligned_io || extend)) {
513 ret = -EAGAIN;
514 goto out;
515 }
516 /*
517 * Make sure inline data cannot be created anymore since we are going
518 * to allocate blocks for DIO. We know the inode does not have any
519 * inline data now because ext4_dio_supported() checked for that.
520 */
521 ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
522
523 offset = iocb->ki_pos;
524 count = ret;
525
526 /*
527 * Unaligned direct IO must be serialized among each other as zeroing
528 * of partial blocks of two competing unaligned IOs can result in data
529 * corruption.
530 *
531 * So we make sure we don't allow any unaligned IO in flight.
532 * For IOs where we need not wait (like unaligned non-AIO DIO),
533 * below inode_dio_wait() may anyway become a no-op, since we start
534 * with exclusive lock.
535 */
536 if (unaligned_io)
537 inode_dio_wait(inode);
538
539 if (extend) {
540 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
541 if (IS_ERR(handle)) {
542 ret = PTR_ERR(handle);
543 goto out;
544 }
545
546 ret = ext4_orphan_add(handle, inode);
547 if (ret) {
548 ext4_journal_stop(handle);
549 goto out;
550 }
551
552 ext4_journal_stop(handle);
553 }
554
555 if (ilock_shared)
556 iomap_ops = &ext4_iomap_overwrite_ops;
557 ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops,
558 (unaligned_io || extend) ? IOMAP_DIO_FORCE_WAIT : 0,
559 NULL, 0);
560 if (ret == -ENOTBLK)
561 ret = 0;
562 if (extend) {
563 /*
564 * We always perform extending DIO write synchronously so by
565 * now the IO is completed and ext4_handle_inode_extension()
566 * was called. Cleanup the inode in case of error or race with
567 * writeback of delalloc blocks.
568 */
569 WARN_ON_ONCE(ret == -EIOCBQUEUED);
570 ext4_inode_extension_cleanup(inode, ret);
571 }
572
573 out:
574 if (ilock_shared)
575 inode_unlock_shared(inode);
576 else
577 inode_unlock(inode);
578
579 if (ret >= 0 && iov_iter_count(from)) {
580 ssize_t err;
581 loff_t endbyte;
582
583 offset = iocb->ki_pos;
584 err = ext4_buffered_write_iter(iocb, from);
585 if (err < 0)
586 return err;
587
588 /*
589 * We need to ensure that the pages within the page cache for
590 * the range covered by this I/O are written to disk and
591 * invalidated. This is in attempt to preserve the expected
592 * direct I/O semantics in the case we fallback to buffered I/O
593 * to complete off the I/O request.
594 */
595 ret += err;
596 endbyte = offset + err - 1;
597 err = filemap_write_and_wait_range(iocb->ki_filp->f_mapping,
598 offset, endbyte);
599 if (!err)
600 invalidate_mapping_pages(iocb->ki_filp->f_mapping,
601 offset >> PAGE_SHIFT,
602 endbyte >> PAGE_SHIFT);
603 }
604
605 return ret;
606 }
607
608 #ifdef CONFIG_FS_DAX
609 static ssize_t
ext4_dax_write_iter(struct kiocb * iocb,struct iov_iter * from)610 ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
611 {
612 ssize_t ret;
613 size_t count;
614 loff_t offset;
615 handle_t *handle;
616 bool extend = false;
617 struct inode *inode = file_inode(iocb->ki_filp);
618
619 if (iocb->ki_flags & IOCB_NOWAIT) {
620 if (!inode_trylock(inode))
621 return -EAGAIN;
622 } else {
623 inode_lock(inode);
624 }
625
626 ret = ext4_write_checks(iocb, from);
627 if (ret <= 0)
628 goto out;
629
630 offset = iocb->ki_pos;
631 count = iov_iter_count(from);
632
633 if (offset + count > EXT4_I(inode)->i_disksize) {
634 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
635 if (IS_ERR(handle)) {
636 ret = PTR_ERR(handle);
637 goto out;
638 }
639
640 ret = ext4_orphan_add(handle, inode);
641 if (ret) {
642 ext4_journal_stop(handle);
643 goto out;
644 }
645
646 extend = true;
647 ext4_journal_stop(handle);
648 }
649
650 ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
651
652 if (extend) {
653 ret = ext4_handle_inode_extension(inode, offset, ret);
654 ext4_inode_extension_cleanup(inode, ret);
655 }
656 out:
657 inode_unlock(inode);
658 if (ret > 0)
659 ret = generic_write_sync(iocb, ret);
660 return ret;
661 }
662 #endif
663
664 static ssize_t
ext4_file_write_iter(struct kiocb * iocb,struct iov_iter * from)665 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
666 {
667 struct inode *inode = file_inode(iocb->ki_filp);
668
669 if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
670 return -EIO;
671
672 #ifdef CONFIG_FS_DAX
673 if (IS_DAX(inode))
674 return ext4_dax_write_iter(iocb, from);
675 #endif
676 if (iocb->ki_flags & IOCB_DIRECT)
677 return ext4_dio_write_iter(iocb, from);
678 else
679 return ext4_buffered_write_iter(iocb, from);
680 }
681
682 #ifdef CONFIG_FS_DAX
ext4_dax_huge_fault(struct vm_fault * vmf,enum page_entry_size pe_size)683 static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf,
684 enum page_entry_size pe_size)
685 {
686 int error = 0;
687 vm_fault_t result;
688 int retries = 0;
689 handle_t *handle = NULL;
690 struct inode *inode = file_inode(vmf->vma->vm_file);
691 struct super_block *sb = inode->i_sb;
692
693 /*
694 * We have to distinguish real writes from writes which will result in a
695 * COW page; COW writes should *not* poke the journal (the file will not
696 * be changed). Doing so would cause unintended failures when mounted
697 * read-only.
698 *
699 * We check for VM_SHARED rather than vmf->cow_page since the latter is
700 * unset for pe_size != PE_SIZE_PTE (i.e. only in do_cow_fault); for
701 * other sizes, dax_iomap_fault will handle splitting / fallback so that
702 * we eventually come back with a COW page.
703 */
704 bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
705 (vmf->vma->vm_flags & VM_SHARED);
706 struct address_space *mapping = vmf->vma->vm_file->f_mapping;
707 pfn_t pfn;
708
709 if (write) {
710 sb_start_pagefault(sb);
711 file_update_time(vmf->vma->vm_file);
712 filemap_invalidate_lock_shared(mapping);
713 retry:
714 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
715 EXT4_DATA_TRANS_BLOCKS(sb));
716 if (IS_ERR(handle)) {
717 filemap_invalidate_unlock_shared(mapping);
718 sb_end_pagefault(sb);
719 return VM_FAULT_SIGBUS;
720 }
721 } else {
722 filemap_invalidate_lock_shared(mapping);
723 }
724 result = dax_iomap_fault(vmf, pe_size, &pfn, &error, &ext4_iomap_ops);
725 if (write) {
726 ext4_journal_stop(handle);
727
728 if ((result & VM_FAULT_ERROR) && error == -ENOSPC &&
729 ext4_should_retry_alloc(sb, &retries))
730 goto retry;
731 /* Handling synchronous page fault? */
732 if (result & VM_FAULT_NEEDDSYNC)
733 result = dax_finish_sync_fault(vmf, pe_size, pfn);
734 filemap_invalidate_unlock_shared(mapping);
735 sb_end_pagefault(sb);
736 } else {
737 filemap_invalidate_unlock_shared(mapping);
738 }
739
740 return result;
741 }
742
ext4_dax_fault(struct vm_fault * vmf)743 static vm_fault_t ext4_dax_fault(struct vm_fault *vmf)
744 {
745 return ext4_dax_huge_fault(vmf, PE_SIZE_PTE);
746 }
747
748 static const struct vm_operations_struct ext4_dax_vm_ops = {
749 .fault = ext4_dax_fault,
750 .huge_fault = ext4_dax_huge_fault,
751 .page_mkwrite = ext4_dax_fault,
752 .pfn_mkwrite = ext4_dax_fault,
753 };
754 #else
755 #define ext4_dax_vm_ops ext4_file_vm_ops
756 #endif
757
758 static const struct vm_operations_struct ext4_file_vm_ops = {
759 .fault = filemap_fault,
760 .map_pages = filemap_map_pages,
761 .page_mkwrite = ext4_page_mkwrite,
762 };
763
ext4_file_mmap(struct file * file,struct vm_area_struct * vma)764 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
765 {
766 struct inode *inode = file->f_mapping->host;
767 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
768 struct dax_device *dax_dev = sbi->s_daxdev;
769
770 if (unlikely(ext4_forced_shutdown(sbi)))
771 return -EIO;
772
773 /*
774 * We don't support synchronous mappings for non-DAX files and
775 * for DAX files if underneath dax_device is not synchronous.
776 */
777 if (!daxdev_mapping_supported(vma, dax_dev))
778 return -EOPNOTSUPP;
779
780 file_accessed(file);
781 if (IS_DAX(file_inode(file))) {
782 vma->vm_ops = &ext4_dax_vm_ops;
783 vm_flags_set(vma, VM_HUGEPAGE);
784 } else {
785 vma->vm_ops = &ext4_file_vm_ops;
786 }
787 return 0;
788 }
789
ext4_sample_last_mounted(struct super_block * sb,struct vfsmount * mnt)790 static int ext4_sample_last_mounted(struct super_block *sb,
791 struct vfsmount *mnt)
792 {
793 struct ext4_sb_info *sbi = EXT4_SB(sb);
794 struct path path;
795 char buf[64], *cp;
796 handle_t *handle;
797 int err;
798
799 if (likely(ext4_test_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED)))
800 return 0;
801
802 if (sb_rdonly(sb) || !sb_start_intwrite_trylock(sb))
803 return 0;
804
805 ext4_set_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED);
806 /*
807 * Sample where the filesystem has been mounted and
808 * store it in the superblock for sysadmin convenience
809 * when trying to sort through large numbers of block
810 * devices or filesystem images.
811 */
812 memset(buf, 0, sizeof(buf));
813 path.mnt = mnt;
814 path.dentry = mnt->mnt_root;
815 cp = d_path(&path, buf, sizeof(buf));
816 err = 0;
817 if (IS_ERR(cp))
818 goto out;
819
820 handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
821 err = PTR_ERR(handle);
822 if (IS_ERR(handle))
823 goto out;
824 BUFFER_TRACE(sbi->s_sbh, "get_write_access");
825 err = ext4_journal_get_write_access(handle, sb, sbi->s_sbh,
826 EXT4_JTR_NONE);
827 if (err)
828 goto out_journal;
829 lock_buffer(sbi->s_sbh);
830 strncpy(sbi->s_es->s_last_mounted, cp,
831 sizeof(sbi->s_es->s_last_mounted));
832 ext4_superblock_csum_set(sb);
833 unlock_buffer(sbi->s_sbh);
834 ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
835 out_journal:
836 ext4_journal_stop(handle);
837 out:
838 sb_end_intwrite(sb);
839 return err;
840 }
841
ext4_file_open(struct inode * inode,struct file * filp)842 static int ext4_file_open(struct inode *inode, struct file *filp)
843 {
844 int ret;
845
846 if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
847 return -EIO;
848
849 ret = ext4_sample_last_mounted(inode->i_sb, filp->f_path.mnt);
850 if (ret)
851 return ret;
852
853 ret = fscrypt_file_open(inode, filp);
854 if (ret)
855 return ret;
856
857 ret = fsverity_file_open(inode, filp);
858 if (ret)
859 return ret;
860
861 /*
862 * Set up the jbd2_inode if we are opening the inode for
863 * writing and the journal is present
864 */
865 if (filp->f_mode & FMODE_WRITE) {
866 ret = ext4_inode_attach_jinode(inode);
867 if (ret < 0)
868 return ret;
869 }
870
871 filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
872 return dquot_file_open(inode, filp);
873 }
874
875 /*
876 * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
877 * by calling generic_file_llseek_size() with the appropriate maxbytes
878 * value for each.
879 */
ext4_llseek(struct file * file,loff_t offset,int whence)880 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
881 {
882 struct inode *inode = file->f_mapping->host;
883 loff_t maxbytes;
884
885 if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
886 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
887 else
888 maxbytes = inode->i_sb->s_maxbytes;
889
890 switch (whence) {
891 default:
892 return generic_file_llseek_size(file, offset, whence,
893 maxbytes, i_size_read(inode));
894 case SEEK_HOLE:
895 inode_lock_shared(inode);
896 offset = iomap_seek_hole(inode, offset,
897 &ext4_iomap_report_ops);
898 inode_unlock_shared(inode);
899 break;
900 case SEEK_DATA:
901 inode_lock_shared(inode);
902 offset = iomap_seek_data(inode, offset,
903 &ext4_iomap_report_ops);
904 inode_unlock_shared(inode);
905 break;
906 }
907
908 if (offset < 0)
909 return offset;
910 return vfs_setpos(file, offset, maxbytes);
911 }
912
913 const struct file_operations ext4_file_operations = {
914 .llseek = ext4_llseek,
915 .read_iter = ext4_file_read_iter,
916 .write_iter = ext4_file_write_iter,
917 .iopoll = iocb_bio_iopoll,
918 .unlocked_ioctl = ext4_ioctl,
919 #ifdef CONFIG_COMPAT
920 .compat_ioctl = ext4_compat_ioctl,
921 #endif
922 .mmap = ext4_file_mmap,
923 .mmap_supported_flags = MAP_SYNC,
924 .open = ext4_file_open,
925 .release = ext4_release_file,
926 .fsync = ext4_sync_file,
927 .get_unmapped_area = thp_get_unmapped_area,
928 .splice_read = generic_file_splice_read,
929 .splice_write = iter_file_splice_write,
930 .fallocate = ext4_fallocate,
931 };
932
933 const struct inode_operations ext4_file_inode_operations = {
934 .setattr = ext4_setattr,
935 .getattr = ext4_file_getattr,
936 .listxattr = ext4_listxattr,
937 .get_acl = ext4_get_acl,
938 .set_acl = ext4_set_acl,
939 .fiemap = ext4_fiemap,
940 .fileattr_get = ext4_fileattr_get,
941 .fileattr_set = ext4_fileattr_set,
942 };
943
944