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/iomap.h>
19#include <linux/module.h>
20#include "blk.h"
21
22static inline struct inode *bdev_file_inode(struct file *file)
23{
24 return file->f_mapping->host;
25}
26
27static blk_opf_t dio_bio_write_op(struct kiocb *iocb)
28{
29 blk_opf_t opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
30
31 /* avoid the need for a I/O completion work item */
32 if (iocb_is_dsync(iocb))
33 opf |= REQ_FUA;
34 return opf;
35}
36
37static bool blkdev_dio_unaligned(struct block_device *bdev, loff_t pos,
38 struct iov_iter *iter)
39{
40 return pos & (bdev_logical_block_size(bdev) - 1) ||
41 !bdev_iter_is_aligned(bdev, iter);
42}
43
44#define DIO_INLINE_BIO_VECS 4
45
46static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb,
47 struct iov_iter *iter, unsigned int nr_pages)
48{
49 struct block_device *bdev = I_BDEV(inode: iocb->ki_filp->f_mapping->host);
50 struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs;
51 loff_t pos = iocb->ki_pos;
52 bool should_dirty = false;
53 struct bio bio;
54 ssize_t ret;
55
56 if (blkdev_dio_unaligned(bdev, pos, iter))
57 return -EINVAL;
58
59 if (nr_pages <= DIO_INLINE_BIO_VECS)
60 vecs = inline_vecs;
61 else {
62 vecs = kmalloc_array(n: nr_pages, size: sizeof(struct bio_vec),
63 GFP_KERNEL);
64 if (!vecs)
65 return -ENOMEM;
66 }
67
68 if (iov_iter_rw(i: iter) == READ) {
69 bio_init(bio: &bio, bdev, table: vecs, max_vecs: nr_pages, opf: REQ_OP_READ);
70 if (user_backed_iter(i: iter))
71 should_dirty = true;
72 } else {
73 bio_init(bio: &bio, bdev, table: vecs, max_vecs: nr_pages, opf: dio_bio_write_op(iocb));
74 }
75 bio.bi_iter.bi_sector = pos >> SECTOR_SHIFT;
76 bio.bi_write_hint = file_inode(f: iocb->ki_filp)->i_write_hint;
77 bio.bi_ioprio = iocb->ki_ioprio;
78
79 ret = bio_iov_iter_get_pages(bio: &bio, iter);
80 if (unlikely(ret))
81 goto out;
82 ret = bio.bi_iter.bi_size;
83
84 if (iov_iter_rw(i: iter) == WRITE)
85 task_io_account_write(bytes: ret);
86
87 if (iocb->ki_flags & IOCB_NOWAIT)
88 bio.bi_opf |= REQ_NOWAIT;
89
90 submit_bio_wait(bio: &bio);
91
92 bio_release_pages(bio: &bio, mark_dirty: should_dirty);
93 if (unlikely(bio.bi_status))
94 ret = blk_status_to_errno(status: bio.bi_status);
95
96out:
97 if (vecs != inline_vecs)
98 kfree(objp: vecs);
99
100 bio_uninit(&bio);
101
102 return ret;
103}
104
105enum {
106 DIO_SHOULD_DIRTY = 1,
107 DIO_IS_SYNC = 2,
108};
109
110struct blkdev_dio {
111 union {
112 struct kiocb *iocb;
113 struct task_struct *waiter;
114 };
115 size_t size;
116 atomic_t ref;
117 unsigned int flags;
118 struct bio bio ____cacheline_aligned_in_smp;
119};
120
121static struct bio_set blkdev_dio_pool;
122
123static void blkdev_bio_end_io(struct bio *bio)
124{
125 struct blkdev_dio *dio = bio->bi_private;
126 bool should_dirty = dio->flags & DIO_SHOULD_DIRTY;
127
128 if (bio->bi_status && !dio->bio.bi_status)
129 dio->bio.bi_status = bio->bi_status;
130
131 if (atomic_dec_and_test(v: &dio->ref)) {
132 if (!(dio->flags & DIO_IS_SYNC)) {
133 struct kiocb *iocb = dio->iocb;
134 ssize_t ret;
135
136 WRITE_ONCE(iocb->private, NULL);
137
138 if (likely(!dio->bio.bi_status)) {
139 ret = dio->size;
140 iocb->ki_pos += ret;
141 } else {
142 ret = blk_status_to_errno(status: dio->bio.bi_status);
143 }
144
145 dio->iocb->ki_complete(iocb, ret);
146 bio_put(&dio->bio);
147 } else {
148 struct task_struct *waiter = dio->waiter;
149
150 WRITE_ONCE(dio->waiter, NULL);
151 blk_wake_io_task(waiter);
152 }
153 }
154
155 if (should_dirty) {
156 bio_check_pages_dirty(bio);
157 } else {
158 bio_release_pages(bio, mark_dirty: false);
159 bio_put(bio);
160 }
161}
162
163static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
164 unsigned int nr_pages)
165{
166 struct block_device *bdev = I_BDEV(inode: iocb->ki_filp->f_mapping->host);
167 struct blk_plug plug;
168 struct blkdev_dio *dio;
169 struct bio *bio;
170 bool is_read = (iov_iter_rw(i: iter) == READ), is_sync;
171 blk_opf_t opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb);
172 loff_t pos = iocb->ki_pos;
173 int ret = 0;
174
175 if (blkdev_dio_unaligned(bdev, pos, iter))
176 return -EINVAL;
177
178 if (iocb->ki_flags & IOCB_ALLOC_CACHE)
179 opf |= REQ_ALLOC_CACHE;
180 bio = bio_alloc_bioset(bdev, nr_vecs: nr_pages, opf, GFP_KERNEL,
181 bs: &blkdev_dio_pool);
182 dio = container_of(bio, struct blkdev_dio, bio);
183 atomic_set(v: &dio->ref, i: 1);
184 /*
185 * Grab an extra reference to ensure the dio structure which is embedded
186 * into the first bio stays around.
187 */
188 bio_get(bio);
189
190 is_sync = is_sync_kiocb(kiocb: iocb);
191 if (is_sync) {
192 dio->flags = DIO_IS_SYNC;
193 dio->waiter = current;
194 } else {
195 dio->flags = 0;
196 dio->iocb = iocb;
197 }
198
199 dio->size = 0;
200 if (is_read && user_backed_iter(i: iter))
201 dio->flags |= DIO_SHOULD_DIRTY;
202
203 blk_start_plug(&plug);
204
205 for (;;) {
206 bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT;
207 bio->bi_write_hint = file_inode(f: iocb->ki_filp)->i_write_hint;
208 bio->bi_private = dio;
209 bio->bi_end_io = blkdev_bio_end_io;
210 bio->bi_ioprio = iocb->ki_ioprio;
211
212 ret = bio_iov_iter_get_pages(bio, iter);
213 if (unlikely(ret)) {
214 bio->bi_status = BLK_STS_IOERR;
215 bio_endio(bio);
216 break;
217 }
218 if (iocb->ki_flags & IOCB_NOWAIT) {
219 /*
220 * This is nonblocking IO, and we need to allocate
221 * another bio if we have data left to map. As we
222 * cannot guarantee that one of the sub bios will not
223 * fail getting issued FOR NOWAIT and as error results
224 * are coalesced across all of them, be safe and ask for
225 * a retry of this from blocking context.
226 */
227 if (unlikely(iov_iter_count(iter))) {
228 bio_release_pages(bio, mark_dirty: false);
229 bio_clear_flag(bio, bit: BIO_REFFED);
230 bio_put(bio);
231 blk_finish_plug(&plug);
232 return -EAGAIN;
233 }
234 bio->bi_opf |= REQ_NOWAIT;
235 }
236
237 if (is_read) {
238 if (dio->flags & DIO_SHOULD_DIRTY)
239 bio_set_pages_dirty(bio);
240 } else {
241 task_io_account_write(bytes: bio->bi_iter.bi_size);
242 }
243 dio->size += bio->bi_iter.bi_size;
244 pos += bio->bi_iter.bi_size;
245
246 nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS);
247 if (!nr_pages) {
248 submit_bio(bio);
249 break;
250 }
251 atomic_inc(v: &dio->ref);
252 submit_bio(bio);
253 bio = bio_alloc(bdev, nr_vecs: nr_pages, opf, GFP_KERNEL);
254 }
255
256 blk_finish_plug(&plug);
257
258 if (!is_sync)
259 return -EIOCBQUEUED;
260
261 for (;;) {
262 set_current_state(TASK_UNINTERRUPTIBLE);
263 if (!READ_ONCE(dio->waiter))
264 break;
265 blk_io_schedule();
266 }
267 __set_current_state(TASK_RUNNING);
268
269 if (!ret)
270 ret = blk_status_to_errno(status: dio->bio.bi_status);
271 if (likely(!ret))
272 ret = dio->size;
273
274 bio_put(&dio->bio);
275 return ret;
276}
277
278static void blkdev_bio_end_io_async(struct bio *bio)
279{
280 struct blkdev_dio *dio = container_of(bio, struct blkdev_dio, bio);
281 struct kiocb *iocb = dio->iocb;
282 ssize_t ret;
283
284 WRITE_ONCE(iocb->private, NULL);
285
286 if (likely(!bio->bi_status)) {
287 ret = dio->size;
288 iocb->ki_pos += ret;
289 } else {
290 ret = blk_status_to_errno(status: bio->bi_status);
291 }
292
293 iocb->ki_complete(iocb, ret);
294
295 if (dio->flags & DIO_SHOULD_DIRTY) {
296 bio_check_pages_dirty(bio);
297 } else {
298 bio_release_pages(bio, mark_dirty: false);
299 bio_put(bio);
300 }
301}
302
303static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb,
304 struct iov_iter *iter,
305 unsigned int nr_pages)
306{
307 struct block_device *bdev = I_BDEV(inode: iocb->ki_filp->f_mapping->host);
308 bool is_read = iov_iter_rw(i: iter) == READ;
309 blk_opf_t opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb);
310 struct blkdev_dio *dio;
311 struct bio *bio;
312 loff_t pos = iocb->ki_pos;
313 int ret = 0;
314
315 if (blkdev_dio_unaligned(bdev, pos, iter))
316 return -EINVAL;
317
318 if (iocb->ki_flags & IOCB_ALLOC_CACHE)
319 opf |= REQ_ALLOC_CACHE;
320 bio = bio_alloc_bioset(bdev, nr_vecs: nr_pages, opf, GFP_KERNEL,
321 bs: &blkdev_dio_pool);
322 dio = container_of(bio, struct blkdev_dio, bio);
323 dio->flags = 0;
324 dio->iocb = iocb;
325 bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT;
326 bio->bi_write_hint = file_inode(f: iocb->ki_filp)->i_write_hint;
327 bio->bi_end_io = blkdev_bio_end_io_async;
328 bio->bi_ioprio = iocb->ki_ioprio;
329
330 if (iov_iter_is_bvec(i: iter)) {
331 /*
332 * Users don't rely on the iterator being in any particular
333 * state for async I/O returning -EIOCBQUEUED, hence we can
334 * avoid expensive iov_iter_advance(). Bypass
335 * bio_iov_iter_get_pages() and set the bvec directly.
336 */
337 bio_iov_bvec_set(bio, iter);
338 } else {
339 ret = bio_iov_iter_get_pages(bio, iter);
340 if (unlikely(ret)) {
341 bio_put(bio);
342 return ret;
343 }
344 }
345 dio->size = bio->bi_iter.bi_size;
346
347 if (is_read) {
348 if (user_backed_iter(i: iter)) {
349 dio->flags |= DIO_SHOULD_DIRTY;
350 bio_set_pages_dirty(bio);
351 }
352 } else {
353 task_io_account_write(bytes: bio->bi_iter.bi_size);
354 }
355
356 if (iocb->ki_flags & IOCB_NOWAIT)
357 bio->bi_opf |= REQ_NOWAIT;
358
359 if (iocb->ki_flags & IOCB_HIPRI) {
360 bio->bi_opf |= REQ_POLLED;
361 submit_bio(bio);
362 WRITE_ONCE(iocb->private, bio);
363 } else {
364 submit_bio(bio);
365 }
366 return -EIOCBQUEUED;
367}
368
369static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
370{
371 unsigned int nr_pages;
372
373 if (!iov_iter_count(i: iter))
374 return 0;
375
376 nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS + 1);
377 if (likely(nr_pages <= BIO_MAX_VECS)) {
378 if (is_sync_kiocb(kiocb: iocb))
379 return __blkdev_direct_IO_simple(iocb, iter, nr_pages);
380 return __blkdev_direct_IO_async(iocb, iter, nr_pages);
381 }
382 return __blkdev_direct_IO(iocb, iter, nr_pages: bio_max_segs(nr_segs: nr_pages));
383}
384
385static int blkdev_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
386 unsigned int flags, struct iomap *iomap, struct iomap *srcmap)
387{
388 struct block_device *bdev = I_BDEV(inode);
389 loff_t isize = i_size_read(inode);
390
391 iomap->bdev = bdev;
392 iomap->offset = ALIGN_DOWN(offset, bdev_logical_block_size(bdev));
393 if (iomap->offset >= isize)
394 return -EIO;
395 iomap->type = IOMAP_MAPPED;
396 iomap->addr = iomap->offset;
397 iomap->length = isize - iomap->offset;
398 iomap->flags |= IOMAP_F_BUFFER_HEAD; /* noop for !CONFIG_BUFFER_HEAD */
399 return 0;
400}
401
402static const struct iomap_ops blkdev_iomap_ops = {
403 .iomap_begin = blkdev_iomap_begin,
404};
405
406#ifdef CONFIG_BUFFER_HEAD
407static int blkdev_get_block(struct inode *inode, sector_t iblock,
408 struct buffer_head *bh, int create)
409{
410 bh->b_bdev = I_BDEV(inode);
411 bh->b_blocknr = iblock;
412 set_buffer_mapped(bh);
413 return 0;
414}
415
416/*
417 * We cannot call mpage_writepages() as it does not take the buffer lock.
418 * We must use block_write_full_folio() directly which holds the buffer
419 * lock. The buffer lock provides the synchronisation with writeback
420 * that filesystems rely on when they use the blockdev's mapping.
421 */
422static int blkdev_writepages(struct address_space *mapping,
423 struct writeback_control *wbc)
424{
425 struct blk_plug plug;
426 int err;
427
428 blk_start_plug(&plug);
429 err = write_cache_pages(mapping, wbc, writepage: block_write_full_folio,
430 data: blkdev_get_block);
431 blk_finish_plug(&plug);
432
433 return err;
434}
435
436static int blkdev_read_folio(struct file *file, struct folio *folio)
437{
438 return block_read_full_folio(folio, blkdev_get_block);
439}
440
441static void blkdev_readahead(struct readahead_control *rac)
442{
443 mpage_readahead(rac, get_block: blkdev_get_block);
444}
445
446static int blkdev_write_begin(struct file *file, struct address_space *mapping,
447 loff_t pos, unsigned len, struct page **pagep, void **fsdata)
448{
449 return block_write_begin(mapping, pos, len, pagep, get_block: blkdev_get_block);
450}
451
452static int blkdev_write_end(struct file *file, struct address_space *mapping,
453 loff_t pos, unsigned len, unsigned copied, struct page *page,
454 void *fsdata)
455{
456 int ret;
457 ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
458
459 unlock_page(page);
460 put_page(page);
461
462 return ret;
463}
464
465const struct address_space_operations def_blk_aops = {
466 .dirty_folio = block_dirty_folio,
467 .invalidate_folio = block_invalidate_folio,
468 .read_folio = blkdev_read_folio,
469 .readahead = blkdev_readahead,
470 .writepages = blkdev_writepages,
471 .write_begin = blkdev_write_begin,
472 .write_end = blkdev_write_end,
473 .migrate_folio = buffer_migrate_folio_norefs,
474 .is_dirty_writeback = buffer_check_dirty_writeback,
475};
476#else /* CONFIG_BUFFER_HEAD */
477static int blkdev_read_folio(struct file *file, struct folio *folio)
478{
479 return iomap_read_folio(folio, &blkdev_iomap_ops);
480}
481
482static void blkdev_readahead(struct readahead_control *rac)
483{
484 iomap_readahead(rac, &blkdev_iomap_ops);
485}
486
487static int blkdev_map_blocks(struct iomap_writepage_ctx *wpc,
488 struct inode *inode, loff_t offset, unsigned int len)
489{
490 loff_t isize = i_size_read(inode);
491
492 if (WARN_ON_ONCE(offset >= isize))
493 return -EIO;
494 if (offset >= wpc->iomap.offset &&
495 offset < wpc->iomap.offset + wpc->iomap.length)
496 return 0;
497 return blkdev_iomap_begin(inode, offset, isize - offset,
498 IOMAP_WRITE, &wpc->iomap, NULL);
499}
500
501static const struct iomap_writeback_ops blkdev_writeback_ops = {
502 .map_blocks = blkdev_map_blocks,
503};
504
505static int blkdev_writepages(struct address_space *mapping,
506 struct writeback_control *wbc)
507{
508 struct iomap_writepage_ctx wpc = { };
509
510 return iomap_writepages(mapping, wbc, &wpc, &blkdev_writeback_ops);
511}
512
513const struct address_space_operations def_blk_aops = {
514 .dirty_folio = filemap_dirty_folio,
515 .release_folio = iomap_release_folio,
516 .invalidate_folio = iomap_invalidate_folio,
517 .read_folio = blkdev_read_folio,
518 .readahead = blkdev_readahead,
519 .writepages = blkdev_writepages,
520 .is_partially_uptodate = iomap_is_partially_uptodate,
521 .error_remove_folio = generic_error_remove_folio,
522 .migrate_folio = filemap_migrate_folio,
523};
524#endif /* CONFIG_BUFFER_HEAD */
525
526/*
527 * for a block special file file_inode(file)->i_size is zero
528 * so we compute the size by hand (just as in block_read/write above)
529 */
530static loff_t blkdev_llseek(struct file *file, loff_t offset, int whence)
531{
532 struct inode *bd_inode = bdev_file_inode(file);
533 loff_t retval;
534
535 inode_lock(inode: bd_inode);
536 retval = fixed_size_llseek(file, offset, whence, size: i_size_read(inode: bd_inode));
537 inode_unlock(inode: bd_inode);
538 return retval;
539}
540
541static int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
542 int datasync)
543{
544 struct block_device *bdev = I_BDEV(inode: filp->f_mapping->host);
545 int error;
546
547 error = file_write_and_wait_range(file: filp, start, end);
548 if (error)
549 return error;
550
551 /*
552 * There is no need to serialise calls to blkdev_issue_flush with
553 * i_mutex and doing so causes performance issues with concurrent
554 * O_SYNC writers to a block device.
555 */
556 error = blkdev_issue_flush(bdev);
557 if (error == -EOPNOTSUPP)
558 error = 0;
559
560 return error;
561}
562
563/**
564 * file_to_blk_mode - get block open flags from file flags
565 * @file: file whose open flags should be converted
566 *
567 * Look at file open flags and generate corresponding block open flags from
568 * them. The function works both for file just being open (e.g. during ->open
569 * callback) and for file that is already open. This is actually non-trivial
570 * (see comment in the function).
571 */
572blk_mode_t file_to_blk_mode(struct file *file)
573{
574 blk_mode_t mode = 0;
575
576 if (file->f_mode & FMODE_READ)
577 mode |= BLK_OPEN_READ;
578 if (file->f_mode & FMODE_WRITE)
579 mode |= BLK_OPEN_WRITE;
580 /*
581 * do_dentry_open() clears O_EXCL from f_flags, use file->private_data
582 * to determine whether the open was exclusive for already open files.
583 */
584 if (file->private_data)
585 mode |= BLK_OPEN_EXCL;
586 else if (file->f_flags & O_EXCL)
587 mode |= BLK_OPEN_EXCL;
588 if (file->f_flags & O_NDELAY)
589 mode |= BLK_OPEN_NDELAY;
590
591 /*
592 * If all bits in O_ACCMODE set (aka O_RDWR | O_WRONLY), the floppy
593 * driver has historically allowed ioctls as if the file was opened for
594 * writing, but does not allow and actual reads or writes.
595 */
596 if ((file->f_flags & O_ACCMODE) == (O_RDWR | O_WRONLY))
597 mode |= BLK_OPEN_WRITE_IOCTL;
598
599 return mode;
600}
601
602static int blkdev_open(struct inode *inode, struct file *filp)
603{
604 struct block_device *bdev;
605 blk_mode_t mode;
606 int ret;
607
608 mode = file_to_blk_mode(file: filp);
609 /* Use the file as the holder. */
610 if (mode & BLK_OPEN_EXCL)
611 filp->private_data = filp;
612 ret = bdev_permission(dev: inode->i_rdev, mode, holder: filp->private_data);
613 if (ret)
614 return ret;
615
616 bdev = blkdev_get_no_open(dev: inode->i_rdev);
617 if (!bdev)
618 return -ENXIO;
619
620 ret = bdev_open(bdev, mode, holder: filp->private_data, NULL, bdev_file: filp);
621 if (ret)
622 blkdev_put_no_open(bdev);
623 return ret;
624}
625
626static int blkdev_release(struct inode *inode, struct file *filp)
627{
628 bdev_release(bdev_file: filp);
629 return 0;
630}
631
632static ssize_t
633blkdev_direct_write(struct kiocb *iocb, struct iov_iter *from)
634{
635 size_t count = iov_iter_count(i: from);
636 ssize_t written;
637
638 written = kiocb_invalidate_pages(iocb, count);
639 if (written) {
640 if (written == -EBUSY)
641 return 0;
642 return written;
643 }
644
645 written = blkdev_direct_IO(iocb, iter: from);
646 if (written > 0) {
647 kiocb_invalidate_post_direct_write(iocb, count);
648 iocb->ki_pos += written;
649 count -= written;
650 }
651 if (written != -EIOCBQUEUED)
652 iov_iter_revert(i: from, bytes: count - iov_iter_count(i: from));
653 return written;
654}
655
656static ssize_t blkdev_buffered_write(struct kiocb *iocb, struct iov_iter *from)
657{
658 return iomap_file_buffered_write(iocb, from, ops: &blkdev_iomap_ops);
659}
660
661/*
662 * Write data to the block device. Only intended for the block device itself
663 * and the raw driver which basically is a fake block device.
664 *
665 * Does not take i_mutex for the write and thus is not for general purpose
666 * use.
667 */
668static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
669{
670 struct file *file = iocb->ki_filp;
671 struct block_device *bdev = I_BDEV(inode: file->f_mapping->host);
672 struct inode *bd_inode = bdev->bd_inode;
673 loff_t size = bdev_nr_bytes(bdev);
674 size_t shorted = 0;
675 ssize_t ret;
676
677 if (bdev_read_only(bdev))
678 return -EPERM;
679
680 if (IS_SWAPFILE(bd_inode) && !is_hibernate_resume_dev(dev: bd_inode->i_rdev))
681 return -ETXTBSY;
682
683 if (!iov_iter_count(i: from))
684 return 0;
685
686 if (iocb->ki_pos >= size)
687 return -ENOSPC;
688
689 if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
690 return -EOPNOTSUPP;
691
692 size -= iocb->ki_pos;
693 if (iov_iter_count(i: from) > size) {
694 shorted = iov_iter_count(i: from) - size;
695 iov_iter_truncate(i: from, count: size);
696 }
697
698 ret = file_update_time(file);
699 if (ret)
700 return ret;
701
702 if (iocb->ki_flags & IOCB_DIRECT) {
703 ret = blkdev_direct_write(iocb, from);
704 if (ret >= 0 && iov_iter_count(i: from))
705 ret = direct_write_fallback(iocb, iter: from, direct_written: ret,
706 buffered_written: blkdev_buffered_write(iocb, from));
707 } else {
708 ret = blkdev_buffered_write(iocb, from);
709 }
710
711 if (ret > 0)
712 ret = generic_write_sync(iocb, count: ret);
713 iov_iter_reexpand(i: from, count: iov_iter_count(i: from) + shorted);
714 return ret;
715}
716
717static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
718{
719 struct block_device *bdev = I_BDEV(inode: iocb->ki_filp->f_mapping->host);
720 loff_t size = bdev_nr_bytes(bdev);
721 loff_t pos = iocb->ki_pos;
722 size_t shorted = 0;
723 ssize_t ret = 0;
724 size_t count;
725
726 if (unlikely(pos + iov_iter_count(to) > size)) {
727 if (pos >= size)
728 return 0;
729 size -= pos;
730 shorted = iov_iter_count(i: to) - size;
731 iov_iter_truncate(i: to, count: size);
732 }
733
734 count = iov_iter_count(i: to);
735 if (!count)
736 goto reexpand; /* skip atime */
737
738 if (iocb->ki_flags & IOCB_DIRECT) {
739 ret = kiocb_write_and_wait(iocb, count);
740 if (ret < 0)
741 goto reexpand;
742 file_accessed(file: iocb->ki_filp);
743
744 ret = blkdev_direct_IO(iocb, iter: to);
745 if (ret >= 0) {
746 iocb->ki_pos += ret;
747 count -= ret;
748 }
749 iov_iter_revert(i: to, bytes: count - iov_iter_count(i: to));
750 if (ret < 0 || !count)
751 goto reexpand;
752 }
753
754 ret = filemap_read(iocb, to, already_read: ret);
755
756reexpand:
757 if (unlikely(shorted))
758 iov_iter_reexpand(i: to, count: iov_iter_count(i: to) + shorted);
759 return ret;
760}
761
762#define BLKDEV_FALLOC_FL_SUPPORTED \
763 (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | \
764 FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE)
765
766static long blkdev_fallocate(struct file *file, int mode, loff_t start,
767 loff_t len)
768{
769 struct inode *inode = bdev_file_inode(file);
770 struct block_device *bdev = I_BDEV(inode);
771 loff_t end = start + len - 1;
772 loff_t isize;
773 int error;
774
775 /* Fail if we don't recognize the flags. */
776 if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
777 return -EOPNOTSUPP;
778
779 /* Don't go off the end of the device. */
780 isize = bdev_nr_bytes(bdev);
781 if (start >= isize)
782 return -EINVAL;
783 if (end >= isize) {
784 if (mode & FALLOC_FL_KEEP_SIZE) {
785 len = isize - start;
786 end = start + len - 1;
787 } else
788 return -EINVAL;
789 }
790
791 /*
792 * Don't allow IO that isn't aligned to logical block size.
793 */
794 if ((start | len) & (bdev_logical_block_size(bdev) - 1))
795 return -EINVAL;
796
797 filemap_invalidate_lock(mapping: inode->i_mapping);
798
799 /*
800 * Invalidate the page cache, including dirty pages, for valid
801 * de-allocate mode calls to fallocate().
802 */
803 switch (mode) {
804 case FALLOC_FL_ZERO_RANGE:
805 case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
806 error = truncate_bdev_range(bdev, mode: file_to_blk_mode(file), lstart: start, lend: end);
807 if (error)
808 goto fail;
809
810 error = blkdev_issue_zeroout(bdev, sector: start >> SECTOR_SHIFT,
811 nr_sects: len >> SECTOR_SHIFT, GFP_KERNEL,
812 BLKDEV_ZERO_NOUNMAP);
813 break;
814 case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
815 error = truncate_bdev_range(bdev, mode: file_to_blk_mode(file), lstart: start, lend: end);
816 if (error)
817 goto fail;
818
819 error = blkdev_issue_zeroout(bdev, sector: start >> SECTOR_SHIFT,
820 nr_sects: len >> SECTOR_SHIFT, GFP_KERNEL,
821 BLKDEV_ZERO_NOFALLBACK);
822 break;
823 case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
824 error = truncate_bdev_range(bdev, mode: file_to_blk_mode(file), lstart: start, lend: end);
825 if (error)
826 goto fail;
827
828 error = blkdev_issue_discard(bdev, sector: start >> SECTOR_SHIFT,
829 nr_sects: len >> SECTOR_SHIFT, GFP_KERNEL);
830 break;
831 default:
832 error = -EOPNOTSUPP;
833 }
834
835 fail:
836 filemap_invalidate_unlock(mapping: inode->i_mapping);
837 return error;
838}
839
840static int blkdev_mmap(struct file *file, struct vm_area_struct *vma)
841{
842 struct inode *bd_inode = bdev_file_inode(file);
843
844 if (bdev_read_only(bdev: I_BDEV(inode: bd_inode)))
845 return generic_file_readonly_mmap(file, vma);
846
847 return generic_file_mmap(file, vma);
848}
849
850const struct file_operations def_blk_fops = {
851 .open = blkdev_open,
852 .release = blkdev_release,
853 .llseek = blkdev_llseek,
854 .read_iter = blkdev_read_iter,
855 .write_iter = blkdev_write_iter,
856 .iopoll = iocb_bio_iopoll,
857 .mmap = blkdev_mmap,
858 .fsync = blkdev_fsync,
859 .unlocked_ioctl = blkdev_ioctl,
860#ifdef CONFIG_COMPAT
861 .compat_ioctl = compat_blkdev_ioctl,
862#endif
863 .splice_read = filemap_splice_read,
864 .splice_write = iter_file_splice_write,
865 .fallocate = blkdev_fallocate,
866};
867
868static __init int blkdev_init(void)
869{
870 return bioset_init(&blkdev_dio_pool, 4,
871 offsetof(struct blkdev_dio, bio),
872 flags: BIOSET_NEED_BVECS|BIOSET_PERCPU_CACHE);
873}
874module_init(blkdev_init);
875

source code of linux/block/fops.c