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 written,size_t count)298 static 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) {
372 truncate:
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
ext4_dio_write_end_io(struct kiocb * iocb,ssize_t size,int error,unsigned int flags)386 static 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
419 static 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 */
ext4_dio_write_checks(struct kiocb * iocb,struct iov_iter * from,bool * ilock_shared,bool * extend)437 static 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
446 restart:
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;
478 out:
479 if (*ilock_shared)
480 inode_unlock_shared(inode);
481 else
482 inode_unlock(inode);
483 return ret;
484 }
485
ext4_dio_write_iter(struct kiocb * iocb,struct iov_iter * from)486 static 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
596 out:
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
632 static ssize_t
ext4_dax_write_iter(struct kiocb * iocb,struct iov_iter * from)633 ext4_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);
677 out:
678 inode_unlock(inode);
679 if (ret > 0)
680 ret = generic_write_sync(iocb, ret);
681 return ret;
682 }
683 #endif
684
685 static ssize_t
ext4_file_write_iter(struct kiocb * iocb,struct iov_iter * from)686 ext4_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
ext4_dax_huge_fault(struct vm_fault * vmf,enum page_entry_size pe_size)704 static 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);
734 retry:
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
ext4_dax_fault(struct vm_fault * vmf)764 static vm_fault_t ext4_dax_fault(struct vm_fault *vmf)
765 {
766 return ext4_dax_huge_fault(vmf, PE_SIZE_PTE);
767 }
768
769 static 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
779 static 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
ext4_file_mmap(struct file * file,struct vm_area_struct * vma)785 static 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
ext4_sample_last_mounted(struct super_block * sb,struct vfsmount * mnt)811 static 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);
856 out_journal:
857 ext4_journal_stop(handle);
858 out:
859 sb_end_intwrite(sb);
860 return err;
861 }
862
ext4_file_open(struct inode * inode,struct file * filp)863 static 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 */
ext4_llseek(struct file * file,loff_t offset,int whence)901 loff_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
934 const 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
954 const struct inode_operations ext4_file_inode_operations = {
955 .setattr = ext4_setattr,
956 .getattr = ext4_file_getattr,
957 .listxattr = ext4_listxattr,
958 .get_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
965