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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
5 * Copyright (C) 2016 - 2020 Christoph Hellwig
6 */
7#include <linux/init.h>
8#include <linux/mm.h>
9#include <linux/blkdev.h>
10#include <linux/buffer_head.h>
11#include <linux/mpage.h>
12#include <linux/uio.h>
13#include <linux/namei.h>
14#include <linux/task_io_accounting_ops.h>
15#include <linux/falloc.h>
16#include <linux/suspend.h>
17#include <linux/fs.h>
18#include <linux/module.h>
19#include "blk.h"
20
21static inline struct inode *bdev_file_inode(struct file *file)
22{
23 return file->f_mapping->host;
24}
25
26static int blkdev_get_block(struct inode *inode, sector_t iblock,
27 struct buffer_head *bh, int create)
28{
29 bh->b_bdev = I_BDEV(inode);
30 bh->b_blocknr = iblock;
31 set_buffer_mapped(bh);
32 return 0;
33}
34
35static blk_opf_t dio_bio_write_op(struct kiocb *iocb)
36{
37 blk_opf_t opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
38
39 /* avoid the need for a I/O completion work item */
40 if (iocb_is_dsync(iocb))
41 opf |= REQ_FUA;
42 return opf;
43}
44
45static bool blkdev_dio_unaligned(struct block_device *bdev, loff_t pos,
46 struct iov_iter *iter)
47{
48 return pos & (bdev_logical_block_size(bdev) - 1) ||
49 !bdev_iter_is_aligned(bdev, iter);
50}
51
52#define DIO_INLINE_BIO_VECS 4
53
54static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb,
55 struct iov_iter *iter, unsigned int nr_pages)
56{
57 struct block_device *bdev = iocb->ki_filp->private_data;
58 struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs;
59 loff_t pos = iocb->ki_pos;
60 bool should_dirty = false;
61 struct bio bio;
62 ssize_t ret;
63
64 if (blkdev_dio_unaligned(bdev, pos, iter))
65 return -EINVAL;
66
67 if (nr_pages <= DIO_INLINE_BIO_VECS)
68 vecs = inline_vecs;
69 else {
70 vecs = kmalloc_array(nr_pages, sizeof(struct bio_vec),
71 GFP_KERNEL);
72 if (!vecs)
73 return -ENOMEM;
74 }
75
76 if (iov_iter_rw(iter) == READ) {
77 bio_init(&bio, bdev, vecs, nr_pages, REQ_OP_READ);
78 if (user_backed_iter(iter))
79 should_dirty = true;
80 } else {
81 bio_init(&bio, bdev, vecs, nr_pages, dio_bio_write_op(iocb));
82 }
83 bio.bi_iter.bi_sector = pos >> SECTOR_SHIFT;
84 bio.bi_ioprio = iocb->ki_ioprio;
85
86 ret = bio_iov_iter_get_pages(&bio, iter);
87 if (unlikely(ret))
88 goto out;
89 ret = bio.bi_iter.bi_size;
90
91 if (iov_iter_rw(iter) == WRITE)
92 task_io_account_write(ret);
93
94 if (iocb->ki_flags & IOCB_NOWAIT)
95 bio.bi_opf |= REQ_NOWAIT;
96
97 submit_bio_wait(&bio);
98
99 bio_release_pages(&bio, should_dirty);
100 if (unlikely(bio.bi_status))
101 ret = blk_status_to_errno(bio.bi_status);
102
103out:
104 if (vecs != inline_vecs)
105 kfree(vecs);
106
107 bio_uninit(&bio);
108
109 return ret;
110}
111
112enum {
113 DIO_SHOULD_DIRTY = 1,
114 DIO_IS_SYNC = 2,
115};
116
117struct blkdev_dio {
118 union {
119 struct kiocb *iocb;
120 struct task_struct *waiter;
121 };
122 size_t size;
123 atomic_t ref;
124 unsigned int flags;
125 struct bio bio ____cacheline_aligned_in_smp;
126};
127
128static struct bio_set blkdev_dio_pool;
129
130static void blkdev_bio_end_io(struct bio *bio)
131{
132 struct blkdev_dio *dio = bio->bi_private;
133 bool should_dirty = dio->flags & DIO_SHOULD_DIRTY;
134
135 if (bio->bi_status && !dio->bio.bi_status)
136 dio->bio.bi_status = bio->bi_status;
137
138 if (atomic_dec_and_test(&dio->ref)) {
139 if (!(dio->flags & DIO_IS_SYNC)) {
140 struct kiocb *iocb = dio->iocb;
141 ssize_t ret;
142
143 WRITE_ONCE(iocb->private, NULL);
144
145 if (likely(!dio->bio.bi_status)) {
146 ret = dio->size;
147 iocb->ki_pos += ret;
148 } else {
149 ret = blk_status_to_errno(dio->bio.bi_status);
150 }
151
152 dio->iocb->ki_complete(iocb, ret);
153 bio_put(&dio->bio);
154 } else {
155 struct task_struct *waiter = dio->waiter;
156
157 WRITE_ONCE(dio->waiter, NULL);
158 blk_wake_io_task(waiter);
159 }
160 }
161
162 if (should_dirty) {
163 bio_check_pages_dirty(bio);
164 } else {
165 bio_release_pages(bio, false);
166 bio_put(bio);
167 }
168}
169
170static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
171 unsigned int nr_pages)
172{
173 struct block_device *bdev = iocb->ki_filp->private_data;
174 struct blk_plug plug;
175 struct blkdev_dio *dio;
176 struct bio *bio;
177 bool is_read = (iov_iter_rw(iter) == READ), is_sync;
178 blk_opf_t opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb);
179 loff_t pos = iocb->ki_pos;
180 int ret = 0;
181
182 if (blkdev_dio_unaligned(bdev, pos, iter))
183 return -EINVAL;
184
185 if (iocb->ki_flags & IOCB_ALLOC_CACHE)
186 opf |= REQ_ALLOC_CACHE;
187 bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL,
188 &blkdev_dio_pool);
189 dio = container_of(bio, struct blkdev_dio, bio);
190 atomic_set(&dio->ref, 1);
191 /*
192 * Grab an extra reference to ensure the dio structure which is embedded
193 * into the first bio stays around.
194 */
195 bio_get(bio);
196
197 is_sync = is_sync_kiocb(iocb);
198 if (is_sync) {
199 dio->flags = DIO_IS_SYNC;
200 dio->waiter = current;
201 } else {
202 dio->flags = 0;
203 dio->iocb = iocb;
204 }
205
206 dio->size = 0;
207 if (is_read && user_backed_iter(iter))
208 dio->flags |= DIO_SHOULD_DIRTY;
209
210 blk_start_plug(&plug);
211
212 for (;;) {
213 bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT;
214 bio->bi_private = dio;
215 bio->bi_end_io = blkdev_bio_end_io;
216 bio->bi_ioprio = iocb->ki_ioprio;
217
218 ret = bio_iov_iter_get_pages(bio, iter);
219 if (unlikely(ret)) {
220 bio->bi_status = BLK_STS_IOERR;
221 bio_endio(bio);
222 break;
223 }
224
225 if (is_read) {
226 if (dio->flags & DIO_SHOULD_DIRTY)
227 bio_set_pages_dirty(bio);
228 } else {
229 task_io_account_write(bio->bi_iter.bi_size);
230 }
231 if (iocb->ki_flags & IOCB_NOWAIT)
232 bio->bi_opf |= REQ_NOWAIT;
233
234 dio->size += bio->bi_iter.bi_size;
235 pos += bio->bi_iter.bi_size;
236
237 nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS);
238 if (!nr_pages) {
239 submit_bio(bio);
240 break;
241 }
242 atomic_inc(&dio->ref);
243 submit_bio(bio);
244 bio = bio_alloc(bdev, nr_pages, opf, GFP_KERNEL);
245 }
246
247 blk_finish_plug(&plug);
248
249 if (!is_sync)
250 return -EIOCBQUEUED;
251
252 for (;;) {
253 set_current_state(TASK_UNINTERRUPTIBLE);
254 if (!READ_ONCE(dio->waiter))
255 break;
256 blk_io_schedule();
257 }
258 __set_current_state(TASK_RUNNING);
259
260 if (!ret)
261 ret = blk_status_to_errno(dio->bio.bi_status);
262 if (likely(!ret))
263 ret = dio->size;
264
265 bio_put(&dio->bio);
266 return ret;
267}
268
269static void blkdev_bio_end_io_async(struct bio *bio)
270{
271 struct blkdev_dio *dio = container_of(bio, struct blkdev_dio, bio);
272 struct kiocb *iocb = dio->iocb;
273 ssize_t ret;
274
275 WRITE_ONCE(iocb->private, NULL);
276
277 if (likely(!bio->bi_status)) {
278 ret = dio->size;
279 iocb->ki_pos += ret;
280 } else {
281 ret = blk_status_to_errno(bio->bi_status);
282 }
283
284 iocb->ki_complete(iocb, ret);
285
286 if (dio->flags & DIO_SHOULD_DIRTY) {
287 bio_check_pages_dirty(bio);
288 } else {
289 bio_release_pages(bio, false);
290 bio_put(bio);
291 }
292}
293
294static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb,
295 struct iov_iter *iter,
296 unsigned int nr_pages)
297{
298 struct block_device *bdev = iocb->ki_filp->private_data;
299 bool is_read = iov_iter_rw(iter) == READ;
300 blk_opf_t opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb);
301 struct blkdev_dio *dio;
302 struct bio *bio;
303 loff_t pos = iocb->ki_pos;
304 int ret = 0;
305
306 if (blkdev_dio_unaligned(bdev, pos, iter))
307 return -EINVAL;
308
309 if (iocb->ki_flags & IOCB_ALLOC_CACHE)
310 opf |= REQ_ALLOC_CACHE;
311 bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL,
312 &blkdev_dio_pool);
313 dio = container_of(bio, struct blkdev_dio, bio);
314 dio->flags = 0;
315 dio->iocb = iocb;
316 bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT;
317 bio->bi_end_io = blkdev_bio_end_io_async;
318 bio->bi_ioprio = iocb->ki_ioprio;
319
320 if (iov_iter_is_bvec(iter)) {
321 /*
322 * Users don't rely on the iterator being in any particular
323 * state for async I/O returning -EIOCBQUEUED, hence we can
324 * avoid expensive iov_iter_advance(). Bypass
325 * bio_iov_iter_get_pages() and set the bvec directly.
326 */
327 bio_iov_bvec_set(bio, iter);
328 } else {
329 ret = bio_iov_iter_get_pages(bio, iter);
330 if (unlikely(ret)) {
331 bio_put(bio);
332 return ret;
333 }
334 }
335 dio->size = bio->bi_iter.bi_size;
336
337 if (is_read) {
338 if (user_backed_iter(iter)) {
339 dio->flags |= DIO_SHOULD_DIRTY;
340 bio_set_pages_dirty(bio);
341 }
342 } else {
343 task_io_account_write(bio->bi_iter.bi_size);
344 }
345
346 if (iocb->ki_flags & IOCB_HIPRI) {
347 bio->bi_opf |= REQ_POLLED | REQ_NOWAIT;
348 submit_bio(bio);
349 WRITE_ONCE(iocb->private, bio);
350 } else {
351 if (iocb->ki_flags & IOCB_NOWAIT)
352 bio->bi_opf |= REQ_NOWAIT;
353 submit_bio(bio);
354 }
355 return -EIOCBQUEUED;
356}
357
358static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
359{
360 unsigned int nr_pages;
361
362 if (!iov_iter_count(iter))
363 return 0;
364
365 nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS + 1);
366 if (likely(nr_pages <= BIO_MAX_VECS)) {
367 if (is_sync_kiocb(iocb))
368 return __blkdev_direct_IO_simple(iocb, iter, nr_pages);
369 return __blkdev_direct_IO_async(iocb, iter, nr_pages);
370 }
371 return __blkdev_direct_IO(iocb, iter, bio_max_segs(nr_pages));
372}
373
374static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
375{
376 return block_write_full_page(page, blkdev_get_block, wbc);
377}
378
379static int blkdev_read_folio(struct file *file, struct folio *folio)
380{
381 return block_read_full_folio(folio, blkdev_get_block);
382}
383
384static void blkdev_readahead(struct readahead_control *rac)
385{
386 mpage_readahead(rac, blkdev_get_block);
387}
388
389static int blkdev_write_begin(struct file *file, struct address_space *mapping,
390 loff_t pos, unsigned len, struct page **pagep, void **fsdata)
391{
392 return block_write_begin(mapping, pos, len, pagep, blkdev_get_block);
393}
394
395static int blkdev_write_end(struct file *file, struct address_space *mapping,
396 loff_t pos, unsigned len, unsigned copied, struct page *page,
397 void *fsdata)
398{
399 int ret;
400 ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
401
402 unlock_page(page);
403 put_page(page);
404
405 return ret;
406}
407
408const struct address_space_operations def_blk_aops = {
409 .dirty_folio = block_dirty_folio,
410 .invalidate_folio = block_invalidate_folio,
411 .read_folio = blkdev_read_folio,
412 .readahead = blkdev_readahead,
413 .writepage = blkdev_writepage,
414 .write_begin = blkdev_write_begin,
415 .write_end = blkdev_write_end,
416 .direct_IO = blkdev_direct_IO,
417 .migrate_folio = buffer_migrate_folio_norefs,
418 .is_dirty_writeback = buffer_check_dirty_writeback,
419};
420
421/*
422 * for a block special file file_inode(file)->i_size is zero
423 * so we compute the size by hand (just as in block_read/write above)
424 */
425static loff_t blkdev_llseek(struct file *file, loff_t offset, int whence)
426{
427 struct inode *bd_inode = bdev_file_inode(file);
428 loff_t retval;
429
430 inode_lock(bd_inode);
431 retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
432 inode_unlock(bd_inode);
433 return retval;
434}
435
436static int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
437 int datasync)
438{
439 struct block_device *bdev = filp->private_data;
440 int error;
441
442 error = file_write_and_wait_range(filp, start, end);
443 if (error)
444 return error;
445
446 /*
447 * There is no need to serialise calls to blkdev_issue_flush with
448 * i_mutex and doing so causes performance issues with concurrent
449 * O_SYNC writers to a block device.
450 */
451 error = blkdev_issue_flush(bdev);
452 if (error == -EOPNOTSUPP)
453 error = 0;
454
455 return error;
456}
457
458static int blkdev_open(struct inode *inode, struct file *filp)
459{
460 struct block_device *bdev;
461
462 /*
463 * Preserve backwards compatibility and allow large file access
464 * even if userspace doesn't ask for it explicitly. Some mkfs
465 * binary needs it. We might want to drop this workaround
466 * during an unstable branch.
467 */
468 filp->f_flags |= O_LARGEFILE;
469 filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
470
471 if (filp->f_flags & O_NDELAY)
472 filp->f_mode |= FMODE_NDELAY;
473 if (filp->f_flags & O_EXCL)
474 filp->f_mode |= FMODE_EXCL;
475 if ((filp->f_flags & O_ACCMODE) == 3)
476 filp->f_mode |= FMODE_WRITE_IOCTL;
477
478 bdev = blkdev_get_by_dev(inode->i_rdev, filp->f_mode, filp);
479 if (IS_ERR(bdev))
480 return PTR_ERR(bdev);
481
482 filp->private_data = bdev;
483 filp->f_mapping = bdev->bd_inode->i_mapping;
484 filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
485 return 0;
486}
487
488static int blkdev_close(struct inode *inode, struct file *filp)
489{
490 struct block_device *bdev = filp->private_data;
491
492 blkdev_put(bdev, filp->f_mode);
493 return 0;
494}
495
496/*
497 * Write data to the block device. Only intended for the block device itself
498 * and the raw driver which basically is a fake block device.
499 *
500 * Does not take i_mutex for the write and thus is not for general purpose
501 * use.
502 */
503static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
504{
505 struct block_device *bdev = iocb->ki_filp->private_data;
506 struct inode *bd_inode = bdev->bd_inode;
507 loff_t size = bdev_nr_bytes(bdev);
508 struct blk_plug plug;
509 size_t shorted = 0;
510 ssize_t ret;
511
512 if (bdev_read_only(bdev))
513 return -EPERM;
514
515 if (IS_SWAPFILE(bd_inode) && !is_hibernate_resume_dev(bd_inode->i_rdev))
516 return -ETXTBSY;
517
518 if (!iov_iter_count(from))
519 return 0;
520
521 if (iocb->ki_pos >= size)
522 return -ENOSPC;
523
524 if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
525 return -EOPNOTSUPP;
526
527 size -= iocb->ki_pos;
528 if (iov_iter_count(from) > size) {
529 shorted = iov_iter_count(from) - size;
530 iov_iter_truncate(from, size);
531 }
532
533 blk_start_plug(&plug);
534 ret = __generic_file_write_iter(iocb, from);
535 if (ret > 0)
536 ret = generic_write_sync(iocb, ret);
537 iov_iter_reexpand(from, iov_iter_count(from) + shorted);
538 blk_finish_plug(&plug);
539 return ret;
540}
541
542static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
543{
544 struct block_device *bdev = iocb->ki_filp->private_data;
545 loff_t size = bdev_nr_bytes(bdev);
546 loff_t pos = iocb->ki_pos;
547 size_t shorted = 0;
548 ssize_t ret = 0;
549 size_t count;
550
551 if (unlikely(pos + iov_iter_count(to) > size)) {
552 if (pos >= size)
553 return 0;
554 size -= pos;
555 shorted = iov_iter_count(to) - size;
556 iov_iter_truncate(to, size);
557 }
558
559 count = iov_iter_count(to);
560 if (!count)
561 goto reexpand; /* skip atime */
562
563 if (iocb->ki_flags & IOCB_DIRECT) {
564 struct address_space *mapping = iocb->ki_filp->f_mapping;
565
566 if (iocb->ki_flags & IOCB_NOWAIT) {
567 if (filemap_range_needs_writeback(mapping, pos,
568 pos + count - 1)) {
569 ret = -EAGAIN;
570 goto reexpand;
571 }
572 } else {
573 ret = filemap_write_and_wait_range(mapping, pos,
574 pos + count - 1);
575 if (ret < 0)
576 goto reexpand;
577 }
578
579 file_accessed(iocb->ki_filp);
580
581 ret = blkdev_direct_IO(iocb, to);
582 if (ret >= 0) {
583 iocb->ki_pos += ret;
584 count -= ret;
585 }
586 iov_iter_revert(to, count - iov_iter_count(to));
587 if (ret < 0 || !count)
588 goto reexpand;
589 }
590
591 ret = filemap_read(iocb, to, ret);
592
593reexpand:
594 if (unlikely(shorted))
595 iov_iter_reexpand(to, iov_iter_count(to) + shorted);
596 return ret;
597}
598
599#define BLKDEV_FALLOC_FL_SUPPORTED \
600 (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | \
601 FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE)
602
603static long blkdev_fallocate(struct file *file, int mode, loff_t start,
604 loff_t len)
605{
606 struct inode *inode = bdev_file_inode(file);
607 struct block_device *bdev = I_BDEV(inode);
608 loff_t end = start + len - 1;
609 loff_t isize;
610 int error;
611
612 /* Fail if we don't recognize the flags. */
613 if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
614 return -EOPNOTSUPP;
615
616 /* Don't go off the end of the device. */
617 isize = bdev_nr_bytes(bdev);
618 if (start >= isize)
619 return -EINVAL;
620 if (end >= isize) {
621 if (mode & FALLOC_FL_KEEP_SIZE) {
622 len = isize - start;
623 end = start + len - 1;
624 } else
625 return -EINVAL;
626 }
627
628 /*
629 * Don't allow IO that isn't aligned to logical block size.
630 */
631 if ((start | len) & (bdev_logical_block_size(bdev) - 1))
632 return -EINVAL;
633
634 filemap_invalidate_lock(inode->i_mapping);
635
636 /* Invalidate the page cache, including dirty pages. */
637 error = truncate_bdev_range(bdev, file->f_mode, start, end);
638 if (error)
639 goto fail;
640
641 switch (mode) {
642 case FALLOC_FL_ZERO_RANGE:
643 case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
644 error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
645 len >> SECTOR_SHIFT, GFP_KERNEL,
646 BLKDEV_ZERO_NOUNMAP);
647 break;
648 case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
649 error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
650 len >> SECTOR_SHIFT, GFP_KERNEL,
651 BLKDEV_ZERO_NOFALLBACK);
652 break;
653 case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
654 error = blkdev_issue_discard(bdev, start >> SECTOR_SHIFT,
655 len >> SECTOR_SHIFT, GFP_KERNEL);
656 break;
657 default:
658 error = -EOPNOTSUPP;
659 }
660
661 fail:
662 filemap_invalidate_unlock(inode->i_mapping);
663 return error;
664}
665
666const struct file_operations def_blk_fops = {
667 .open = blkdev_open,
668 .release = blkdev_close,
669 .llseek = blkdev_llseek,
670 .read_iter = blkdev_read_iter,
671 .write_iter = blkdev_write_iter,
672 .iopoll = iocb_bio_iopoll,
673 .mmap = generic_file_mmap,
674 .fsync = blkdev_fsync,
675 .unlocked_ioctl = blkdev_ioctl,
676#ifdef CONFIG_COMPAT
677 .compat_ioctl = compat_blkdev_ioctl,
678#endif
679 .splice_read = generic_file_splice_read,
680 .splice_write = iter_file_splice_write,
681 .fallocate = blkdev_fallocate,
682};
683
684static __init int blkdev_init(void)
685{
686 return bioset_init(&blkdev_dio_pool, 4,
687 offsetof(struct blkdev_dio, bio),
688 BIOSET_NEED_BVECS|BIOSET_PERCPU_CACHE);
689}
690module_init(blkdev_init);