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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
8#include <linux/init.h>
9#include <linux/mm.h>
10#include <linux/fcntl.h>
11#include <linux/slab.h>
12#include <linux/kmod.h>
13#include <linux/major.h>
14#include <linux/device_cgroup.h>
15#include <linux/highmem.h>
16#include <linux/blkdev.h>
17#include <linux/backing-dev.h>
18#include <linux/module.h>
19#include <linux/blkpg.h>
20#include <linux/magic.h>
21#include <linux/buffer_head.h>
22#include <linux/swap.h>
23#include <linux/pagevec.h>
24#include <linux/writeback.h>
25#include <linux/mpage.h>
26#include <linux/mount.h>
27#include <linux/pseudo_fs.h>
28#include <linux/uio.h>
29#include <linux/namei.h>
30#include <linux/log2.h>
31#include <linux/cleancache.h>
32#include <linux/task_io_accounting_ops.h>
33#include <linux/falloc.h>
34#include <linux/part_stat.h>
35#include <linux/uaccess.h>
36#include <linux/suspend.h>
37#include "internal.h"
38
39struct bdev_inode {
40 struct block_device bdev;
41 struct inode vfs_inode;
42};
43
44static const struct address_space_operations def_blk_aops;
45
46static inline struct bdev_inode *BDEV_I(struct inode *inode)
47{
48 return container_of(inode, struct bdev_inode, vfs_inode);
49}
50
51struct block_device *I_BDEV(struct inode *inode)
52{
53 return &BDEV_I(inode)->bdev;
54}
55EXPORT_SYMBOL(I_BDEV);
56
57static void bdev_write_inode(struct block_device *bdev)
58{
59 struct inode *inode = bdev->bd_inode;
60 int ret;
61
62 spin_lock(&inode->i_lock);
63 while (inode->i_state & I_DIRTY) {
64 spin_unlock(&inode->i_lock);
65 ret = write_inode_now(inode, true);
66 if (ret) {
67 char name[BDEVNAME_SIZE];
68 pr_warn_ratelimited("VFS: Dirty inode writeback failed "
69 "for block device %s (err=%d).\n",
70 bdevname(bdev, name), ret);
71 }
72 spin_lock(&inode->i_lock);
73 }
74 spin_unlock(&inode->i_lock);
75}
76
77/* Kill _all_ buffers and pagecache , dirty or not.. */
78static void kill_bdev(struct block_device *bdev)
79{
80 struct address_space *mapping = bdev->bd_inode->i_mapping;
81
82 if (mapping_empty(mapping))
83 return;
84
85 invalidate_bh_lrus();
86 truncate_inode_pages(mapping, 0);
87}
88
89/* Invalidate clean unused buffers and pagecache. */
90void invalidate_bdev(struct block_device *bdev)
91{
92 struct address_space *mapping = bdev->bd_inode->i_mapping;
93
94 if (mapping->nrpages) {
95 invalidate_bh_lrus();
96 lru_add_drain_all(); /* make sure all lru add caches are flushed */
97 invalidate_mapping_pages(mapping, 0, -1);
98 }
99 /* 99% of the time, we don't need to flush the cleancache on the bdev.
100 * But, for the strange corners, lets be cautious
101 */
102 cleancache_invalidate_inode(mapping);
103}
104EXPORT_SYMBOL(invalidate_bdev);
105
106/*
107 * Drop all buffers & page cache for given bdev range. This function bails
108 * with error if bdev has other exclusive owner (such as filesystem).
109 */
110int truncate_bdev_range(struct block_device *bdev, fmode_t mode,
111 loff_t lstart, loff_t lend)
112{
113 /*
114 * If we don't hold exclusive handle for the device, upgrade to it
115 * while we discard the buffer cache to avoid discarding buffers
116 * under live filesystem.
117 */
118 if (!(mode & FMODE_EXCL)) {
119 int err = bd_prepare_to_claim(bdev, truncate_bdev_range);
120 if (err)
121 goto invalidate;
122 }
123
124 truncate_inode_pages_range(bdev->bd_inode->i_mapping, lstart, lend);
125 if (!(mode & FMODE_EXCL))
126 bd_abort_claiming(bdev, truncate_bdev_range);
127 return 0;
128
129invalidate:
130 /*
131 * Someone else has handle exclusively open. Try invalidating instead.
132 * The 'end' argument is inclusive so the rounding is safe.
133 */
134 return invalidate_inode_pages2_range(bdev->bd_inode->i_mapping,
135 lstart >> PAGE_SHIFT,
136 lend >> PAGE_SHIFT);
137}
138
139static void set_init_blocksize(struct block_device *bdev)
140{
141 unsigned int bsize = bdev_logical_block_size(bdev);
142 loff_t size = i_size_read(bdev->bd_inode);
143
144 while (bsize < PAGE_SIZE) {
145 if (size & bsize)
146 break;
147 bsize <<= 1;
148 }
149 bdev->bd_inode->i_blkbits = blksize_bits(bsize);
150}
151
152int set_blocksize(struct block_device *bdev, int size)
153{
154 /* Size must be a power of two, and between 512 and PAGE_SIZE */
155 if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
156 return -EINVAL;
157
158 /* Size cannot be smaller than the size supported by the device */
159 if (size < bdev_logical_block_size(bdev))
160 return -EINVAL;
161
162 /* Don't change the size if it is same as current */
163 if (bdev->bd_inode->i_blkbits != blksize_bits(size)) {
164 sync_blockdev(bdev);
165 bdev->bd_inode->i_blkbits = blksize_bits(size);
166 kill_bdev(bdev);
167 }
168 return 0;
169}
170
171EXPORT_SYMBOL(set_blocksize);
172
173int sb_set_blocksize(struct super_block *sb, int size)
174{
175 if (set_blocksize(sb->s_bdev, size))
176 return 0;
177 /* If we get here, we know size is power of two
178 * and it's value is between 512 and PAGE_SIZE */
179 sb->s_blocksize = size;
180 sb->s_blocksize_bits = blksize_bits(size);
181 return sb->s_blocksize;
182}
183
184EXPORT_SYMBOL(sb_set_blocksize);
185
186int sb_min_blocksize(struct super_block *sb, int size)
187{
188 int minsize = bdev_logical_block_size(sb->s_bdev);
189 if (size < minsize)
190 size = minsize;
191 return sb_set_blocksize(sb, size);
192}
193
194EXPORT_SYMBOL(sb_min_blocksize);
195
196static int
197blkdev_get_block(struct inode *inode, sector_t iblock,
198 struct buffer_head *bh, int create)
199{
200 bh->b_bdev = I_BDEV(inode);
201 bh->b_blocknr = iblock;
202 set_buffer_mapped(bh);
203 return 0;
204}
205
206static struct inode *bdev_file_inode(struct file *file)
207{
208 return file->f_mapping->host;
209}
210
211static unsigned int dio_bio_write_op(struct kiocb *iocb)
212{
213 unsigned int op = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
214
215 /* avoid the need for a I/O completion work item */
216 if (iocb->ki_flags & IOCB_DSYNC)
217 op |= REQ_FUA;
218 return op;
219}
220
221#define DIO_INLINE_BIO_VECS 4
222
223static void blkdev_bio_end_io_simple(struct bio *bio)
224{
225 struct task_struct *waiter = bio->bi_private;
226
227 WRITE_ONCE(bio->bi_private, NULL);
228 blk_wake_io_task(waiter);
229}
230
231static ssize_t
232__blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
233 unsigned int nr_pages)
234{
235 struct file *file = iocb->ki_filp;
236 struct block_device *bdev = I_BDEV(bdev_file_inode(file));
237 struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs;
238 loff_t pos = iocb->ki_pos;
239 bool should_dirty = false;
240 struct bio bio;
241 ssize_t ret;
242 blk_qc_t qc;
243
244 if ((pos | iov_iter_alignment(iter)) &
245 (bdev_logical_block_size(bdev) - 1))
246 return -EINVAL;
247
248 if (nr_pages <= DIO_INLINE_BIO_VECS)
249 vecs = inline_vecs;
250 else {
251 vecs = kmalloc_array(nr_pages, sizeof(struct bio_vec),
252 GFP_KERNEL);
253 if (!vecs)
254 return -ENOMEM;
255 }
256
257 bio_init(&bio, vecs, nr_pages);
258 bio_set_dev(&bio, bdev);
259 bio.bi_iter.bi_sector = pos >> 9;
260 bio.bi_write_hint = iocb->ki_hint;
261 bio.bi_private = current;
262 bio.bi_end_io = blkdev_bio_end_io_simple;
263 bio.bi_ioprio = iocb->ki_ioprio;
264
265 ret = bio_iov_iter_get_pages(&bio, iter);
266 if (unlikely(ret))
267 goto out;
268 ret = bio.bi_iter.bi_size;
269
270 if (iov_iter_rw(iter) == READ) {
271 bio.bi_opf = REQ_OP_READ;
272 if (iter_is_iovec(iter))
273 should_dirty = true;
274 } else {
275 bio.bi_opf = dio_bio_write_op(iocb);
276 task_io_account_write(ret);
277 }
278 if (iocb->ki_flags & IOCB_NOWAIT)
279 bio.bi_opf |= REQ_NOWAIT;
280 if (iocb->ki_flags & IOCB_HIPRI)
281 bio_set_polled(&bio, iocb);
282
283 qc = submit_bio(&bio);
284 for (;;) {
285 set_current_state(TASK_UNINTERRUPTIBLE);
286 if (!READ_ONCE(bio.bi_private))
287 break;
288 if (!(iocb->ki_flags & IOCB_HIPRI) ||
289 !blk_poll(bdev_get_queue(bdev), qc, true))
290 blk_io_schedule();
291 }
292 __set_current_state(TASK_RUNNING);
293
294 bio_release_pages(&bio, should_dirty);
295 if (unlikely(bio.bi_status))
296 ret = blk_status_to_errno(bio.bi_status);
297
298out:
299 if (vecs != inline_vecs)
300 kfree(vecs);
301
302 bio_uninit(&bio);
303
304 return ret;
305}
306
307struct blkdev_dio {
308 union {
309 struct kiocb *iocb;
310 struct task_struct *waiter;
311 };
312 size_t size;
313 atomic_t ref;
314 bool multi_bio : 1;
315 bool should_dirty : 1;
316 bool is_sync : 1;
317 struct bio bio;
318};
319
320static struct bio_set blkdev_dio_pool;
321
322static int blkdev_iopoll(struct kiocb *kiocb, bool wait)
323{
324 struct block_device *bdev = I_BDEV(kiocb->ki_filp->f_mapping->host);
325 struct request_queue *q = bdev_get_queue(bdev);
326
327 return blk_poll(q, READ_ONCE(kiocb->ki_cookie), wait);
328}
329
330static void blkdev_bio_end_io(struct bio *bio)
331{
332 struct blkdev_dio *dio = bio->bi_private;
333 bool should_dirty = dio->should_dirty;
334
335 if (bio->bi_status && !dio->bio.bi_status)
336 dio->bio.bi_status = bio->bi_status;
337
338 if (!dio->multi_bio || atomic_dec_and_test(&dio->ref)) {
339 if (!dio->is_sync) {
340 struct kiocb *iocb = dio->iocb;
341 ssize_t ret;
342
343 if (likely(!dio->bio.bi_status)) {
344 ret = dio->size;
345 iocb->ki_pos += ret;
346 } else {
347 ret = blk_status_to_errno(dio->bio.bi_status);
348 }
349
350 dio->iocb->ki_complete(iocb, ret, 0);
351 if (dio->multi_bio)
352 bio_put(&dio->bio);
353 } else {
354 struct task_struct *waiter = dio->waiter;
355
356 WRITE_ONCE(dio->waiter, NULL);
357 blk_wake_io_task(waiter);
358 }
359 }
360
361 if (should_dirty) {
362 bio_check_pages_dirty(bio);
363 } else {
364 bio_release_pages(bio, false);
365 bio_put(bio);
366 }
367}
368
369static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
370 unsigned int nr_pages)
371{
372 struct file *file = iocb->ki_filp;
373 struct inode *inode = bdev_file_inode(file);
374 struct block_device *bdev = I_BDEV(inode);
375 struct blk_plug plug;
376 struct blkdev_dio *dio;
377 struct bio *bio;
378 bool is_poll = (iocb->ki_flags & IOCB_HIPRI) != 0;
379 bool is_read = (iov_iter_rw(iter) == READ), is_sync;
380 loff_t pos = iocb->ki_pos;
381 blk_qc_t qc = BLK_QC_T_NONE;
382 int ret = 0;
383
384 if ((pos | iov_iter_alignment(iter)) &
385 (bdev_logical_block_size(bdev) - 1))
386 return -EINVAL;
387
388 bio = bio_alloc_bioset(GFP_KERNEL, nr_pages, &blkdev_dio_pool);
389
390 dio = container_of(bio, struct blkdev_dio, bio);
391 dio->is_sync = is_sync = is_sync_kiocb(iocb);
392 if (dio->is_sync) {
393 dio->waiter = current;
394 bio_get(bio);
395 } else {
396 dio->iocb = iocb;
397 }
398
399 dio->size = 0;
400 dio->multi_bio = false;
401 dio->should_dirty = is_read && iter_is_iovec(iter);
402
403 /*
404 * Don't plug for HIPRI/polled IO, as those should go straight
405 * to issue
406 */
407 if (!is_poll)
408 blk_start_plug(&plug);
409
410 for (;;) {
411 bio_set_dev(bio, bdev);
412 bio->bi_iter.bi_sector = pos >> 9;
413 bio->bi_write_hint = iocb->ki_hint;
414 bio->bi_private = dio;
415 bio->bi_end_io = blkdev_bio_end_io;
416 bio->bi_ioprio = iocb->ki_ioprio;
417
418 ret = bio_iov_iter_get_pages(bio, iter);
419 if (unlikely(ret)) {
420 bio->bi_status = BLK_STS_IOERR;
421 bio_endio(bio);
422 break;
423 }
424
425 if (is_read) {
426 bio->bi_opf = REQ_OP_READ;
427 if (dio->should_dirty)
428 bio_set_pages_dirty(bio);
429 } else {
430 bio->bi_opf = dio_bio_write_op(iocb);
431 task_io_account_write(bio->bi_iter.bi_size);
432 }
433 if (iocb->ki_flags & IOCB_NOWAIT)
434 bio->bi_opf |= REQ_NOWAIT;
435
436 dio->size += bio->bi_iter.bi_size;
437 pos += bio->bi_iter.bi_size;
438
439 nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS);
440 if (!nr_pages) {
441 bool polled = false;
442
443 if (iocb->ki_flags & IOCB_HIPRI) {
444 bio_set_polled(bio, iocb);
445 polled = true;
446 }
447
448 qc = submit_bio(bio);
449
450 if (polled)
451 WRITE_ONCE(iocb->ki_cookie, qc);
452 break;
453 }
454
455 if (!dio->multi_bio) {
456 /*
457 * AIO needs an extra reference to ensure the dio
458 * structure which is embedded into the first bio
459 * stays around.
460 */
461 if (!is_sync)
462 bio_get(bio);
463 dio->multi_bio = true;
464 atomic_set(&dio->ref, 2);
465 } else {
466 atomic_inc(&dio->ref);
467 }
468
469 submit_bio(bio);
470 bio = bio_alloc(GFP_KERNEL, nr_pages);
471 }
472
473 if (!is_poll)
474 blk_finish_plug(&plug);
475
476 if (!is_sync)
477 return -EIOCBQUEUED;
478
479 for (;;) {
480 set_current_state(TASK_UNINTERRUPTIBLE);
481 if (!READ_ONCE(dio->waiter))
482 break;
483
484 if (!(iocb->ki_flags & IOCB_HIPRI) ||
485 !blk_poll(bdev_get_queue(bdev), qc, true))
486 blk_io_schedule();
487 }
488 __set_current_state(TASK_RUNNING);
489
490 if (!ret)
491 ret = blk_status_to_errno(dio->bio.bi_status);
492 if (likely(!ret))
493 ret = dio->size;
494
495 bio_put(&dio->bio);
496 return ret;
497}
498
499static ssize_t
500blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
501{
502 unsigned int nr_pages;
503
504 if (!iov_iter_count(iter))
505 return 0;
506
507 nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS + 1);
508 if (is_sync_kiocb(iocb) && nr_pages <= BIO_MAX_VECS)
509 return __blkdev_direct_IO_simple(iocb, iter, nr_pages);
510
511 return __blkdev_direct_IO(iocb, iter, bio_max_segs(nr_pages));
512}
513
514static __init int blkdev_init(void)
515{
516 return bioset_init(&blkdev_dio_pool, 4, offsetof(struct blkdev_dio, bio), BIOSET_NEED_BVECS);
517}
518module_init(blkdev_init);
519
520int __sync_blockdev(struct block_device *bdev, int wait)
521{
522 if (!bdev)
523 return 0;
524 if (!wait)
525 return filemap_flush(bdev->bd_inode->i_mapping);
526 return filemap_write_and_wait(bdev->bd_inode->i_mapping);
527}
528
529/*
530 * Write out and wait upon all the dirty data associated with a block
531 * device via its mapping. Does not take the superblock lock.
532 */
533int sync_blockdev(struct block_device *bdev)
534{
535 return __sync_blockdev(bdev, 1);
536}
537EXPORT_SYMBOL(sync_blockdev);
538
539/*
540 * Write out and wait upon all dirty data associated with this
541 * device. Filesystem data as well as the underlying block
542 * device. Takes the superblock lock.
543 */
544int fsync_bdev(struct block_device *bdev)
545{
546 struct super_block *sb = get_super(bdev);
547 if (sb) {
548 int res = sync_filesystem(sb);
549 drop_super(sb);
550 return res;
551 }
552 return sync_blockdev(bdev);
553}
554EXPORT_SYMBOL(fsync_bdev);
555
556/**
557 * freeze_bdev -- lock a filesystem and force it into a consistent state
558 * @bdev: blockdevice to lock
559 *
560 * If a superblock is found on this device, we take the s_umount semaphore
561 * on it to make sure nobody unmounts until the snapshot creation is done.
562 * The reference counter (bd_fsfreeze_count) guarantees that only the last
563 * unfreeze process can unfreeze the frozen filesystem actually when multiple
564 * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
565 * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
566 * actually.
567 */
568int freeze_bdev(struct block_device *bdev)
569{
570 struct super_block *sb;
571 int error = 0;
572
573 mutex_lock(&bdev->bd_fsfreeze_mutex);
574 if (++bdev->bd_fsfreeze_count > 1)
575 goto done;
576
577 sb = get_active_super(bdev);
578 if (!sb)
579 goto sync;
580 if (sb->s_op->freeze_super)
581 error = sb->s_op->freeze_super(sb);
582 else
583 error = freeze_super(sb);
584 deactivate_super(sb);
585
586 if (error) {
587 bdev->bd_fsfreeze_count--;
588 goto done;
589 }
590 bdev->bd_fsfreeze_sb = sb;
591
592sync:
593 sync_blockdev(bdev);
594done:
595 mutex_unlock(&bdev->bd_fsfreeze_mutex);
596 return error;
597}
598EXPORT_SYMBOL(freeze_bdev);
599
600/**
601 * thaw_bdev -- unlock filesystem
602 * @bdev: blockdevice to unlock
603 *
604 * Unlocks the filesystem and marks it writeable again after freeze_bdev().
605 */
606int thaw_bdev(struct block_device *bdev)
607{
608 struct super_block *sb;
609 int error = -EINVAL;
610
611 mutex_lock(&bdev->bd_fsfreeze_mutex);
612 if (!bdev->bd_fsfreeze_count)
613 goto out;
614
615 error = 0;
616 if (--bdev->bd_fsfreeze_count > 0)
617 goto out;
618
619 sb = bdev->bd_fsfreeze_sb;
620 if (!sb)
621 goto out;
622
623 if (sb->s_op->thaw_super)
624 error = sb->s_op->thaw_super(sb);
625 else
626 error = thaw_super(sb);
627 if (error)
628 bdev->bd_fsfreeze_count++;
629 else
630 bdev->bd_fsfreeze_sb = NULL;
631out:
632 mutex_unlock(&bdev->bd_fsfreeze_mutex);
633 return error;
634}
635EXPORT_SYMBOL(thaw_bdev);
636
637static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
638{
639 return block_write_full_page(page, blkdev_get_block, wbc);
640}
641
642static int blkdev_readpage(struct file * file, struct page * page)
643{
644 return block_read_full_page(page, blkdev_get_block);
645}
646
647static void blkdev_readahead(struct readahead_control *rac)
648{
649 mpage_readahead(rac, blkdev_get_block);
650}
651
652static int blkdev_write_begin(struct file *file, struct address_space *mapping,
653 loff_t pos, unsigned len, unsigned flags,
654 struct page **pagep, void **fsdata)
655{
656 return block_write_begin(mapping, pos, len, flags, pagep,
657 blkdev_get_block);
658}
659
660static int blkdev_write_end(struct file *file, struct address_space *mapping,
661 loff_t pos, unsigned len, unsigned copied,
662 struct page *page, void *fsdata)
663{
664 int ret;
665 ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
666
667 unlock_page(page);
668 put_page(page);
669
670 return ret;
671}
672
673/*
674 * private llseek:
675 * for a block special file file_inode(file)->i_size is zero
676 * so we compute the size by hand (just as in block_read/write above)
677 */
678static loff_t block_llseek(struct file *file, loff_t offset, int whence)
679{
680 struct inode *bd_inode = bdev_file_inode(file);
681 loff_t retval;
682
683 inode_lock(bd_inode);
684 retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
685 inode_unlock(bd_inode);
686 return retval;
687}
688
689int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
690{
691 struct inode *bd_inode = bdev_file_inode(filp);
692 struct block_device *bdev = I_BDEV(bd_inode);
693 int error;
694
695 error = file_write_and_wait_range(filp, start, end);
696 if (error)
697 return error;
698
699 /*
700 * There is no need to serialise calls to blkdev_issue_flush with
701 * i_mutex and doing so causes performance issues with concurrent
702 * O_SYNC writers to a block device.
703 */
704 error = blkdev_issue_flush(bdev);
705 if (error == -EOPNOTSUPP)
706 error = 0;
707
708 return error;
709}
710EXPORT_SYMBOL(blkdev_fsync);
711
712/**
713 * bdev_read_page() - Start reading a page from a block device
714 * @bdev: The device to read the page from
715 * @sector: The offset on the device to read the page to (need not be aligned)
716 * @page: The page to read
717 *
718 * On entry, the page should be locked. It will be unlocked when the page
719 * has been read. If the block driver implements rw_page synchronously,
720 * that will be true on exit from this function, but it need not be.
721 *
722 * Errors returned by this function are usually "soft", eg out of memory, or
723 * queue full; callers should try a different route to read this page rather
724 * than propagate an error back up the stack.
725 *
726 * Return: negative errno if an error occurs, 0 if submission was successful.
727 */
728int bdev_read_page(struct block_device *bdev, sector_t sector,
729 struct page *page)
730{
731 const struct block_device_operations *ops = bdev->bd_disk->fops;
732 int result = -EOPNOTSUPP;
733
734 if (!ops->rw_page || bdev_get_integrity(bdev))
735 return result;
736
737 result = blk_queue_enter(bdev->bd_disk->queue, 0);
738 if (result)
739 return result;
740 result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
741 REQ_OP_READ);
742 blk_queue_exit(bdev->bd_disk->queue);
743 return result;
744}
745
746/**
747 * bdev_write_page() - Start writing a page to a block device
748 * @bdev: The device to write the page to
749 * @sector: The offset on the device to write the page to (need not be aligned)
750 * @page: The page to write
751 * @wbc: The writeback_control for the write
752 *
753 * On entry, the page should be locked and not currently under writeback.
754 * On exit, if the write started successfully, the page will be unlocked and
755 * under writeback. If the write failed already (eg the driver failed to
756 * queue the page to the device), the page will still be locked. If the
757 * caller is a ->writepage implementation, it will need to unlock the page.
758 *
759 * Errors returned by this function are usually "soft", eg out of memory, or
760 * queue full; callers should try a different route to write this page rather
761 * than propagate an error back up the stack.
762 *
763 * Return: negative errno if an error occurs, 0 if submission was successful.
764 */
765int bdev_write_page(struct block_device *bdev, sector_t sector,
766 struct page *page, struct writeback_control *wbc)
767{
768 int result;
769 const struct block_device_operations *ops = bdev->bd_disk->fops;
770
771 if (!ops->rw_page || bdev_get_integrity(bdev))
772 return -EOPNOTSUPP;
773 result = blk_queue_enter(bdev->bd_disk->queue, 0);
774 if (result)
775 return result;
776
777 set_page_writeback(page);
778 result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
779 REQ_OP_WRITE);
780 if (result) {
781 end_page_writeback(page);
782 } else {
783 clean_page_buffers(page);
784 unlock_page(page);
785 }
786 blk_queue_exit(bdev->bd_disk->queue);
787 return result;
788}
789
790/*
791 * pseudo-fs
792 */
793
794static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
795static struct kmem_cache * bdev_cachep __read_mostly;
796
797static struct inode *bdev_alloc_inode(struct super_block *sb)
798{
799 struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
800
801 if (!ei)
802 return NULL;
803 memset(&ei->bdev, 0, sizeof(ei->bdev));
804 ei->bdev.bd_bdi = &noop_backing_dev_info;
805 return &ei->vfs_inode;
806}
807
808static void bdev_free_inode(struct inode *inode)
809{
810 struct block_device *bdev = I_BDEV(inode);
811
812 free_percpu(bdev->bd_stats);
813 kfree(bdev->bd_meta_info);
814
815 if (!bdev_is_partition(bdev))
816 kfree(bdev->bd_disk);
817 kmem_cache_free(bdev_cachep, BDEV_I(inode));
818}
819
820static void init_once(void *data)
821{
822 struct bdev_inode *ei = data;
823
824 inode_init_once(&ei->vfs_inode);
825}
826
827static void bdev_evict_inode(struct inode *inode)
828{
829 struct block_device *bdev = &BDEV_I(inode)->bdev;
830 truncate_inode_pages_final(&inode->i_data);
831 invalidate_inode_buffers(inode); /* is it needed here? */
832 clear_inode(inode);
833 /* Detach inode from wb early as bdi_put() may free bdi->wb */
834 inode_detach_wb(inode);
835 if (bdev->bd_bdi != &noop_backing_dev_info) {
836 bdi_put(bdev->bd_bdi);
837 bdev->bd_bdi = &noop_backing_dev_info;
838 }
839}
840
841static const struct super_operations bdev_sops = {
842 .statfs = simple_statfs,
843 .alloc_inode = bdev_alloc_inode,
844 .free_inode = bdev_free_inode,
845 .drop_inode = generic_delete_inode,
846 .evict_inode = bdev_evict_inode,
847};
848
849static int bd_init_fs_context(struct fs_context *fc)
850{
851 struct pseudo_fs_context *ctx = init_pseudo(fc, BDEVFS_MAGIC);
852 if (!ctx)
853 return -ENOMEM;
854 fc->s_iflags |= SB_I_CGROUPWB;
855 ctx->ops = &bdev_sops;
856 return 0;
857}
858
859static struct file_system_type bd_type = {
860 .name = "bdev",
861 .init_fs_context = bd_init_fs_context,
862 .kill_sb = kill_anon_super,
863};
864
865struct super_block *blockdev_superblock __read_mostly;
866EXPORT_SYMBOL_GPL(blockdev_superblock);
867
868void __init bdev_cache_init(void)
869{
870 int err;
871 static struct vfsmount *bd_mnt;
872
873 bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
874 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
875 SLAB_MEM_SPREAD|SLAB_ACCOUNT|SLAB_PANIC),
876 init_once);
877 err = register_filesystem(&bd_type);
878 if (err)
879 panic("Cannot register bdev pseudo-fs");
880 bd_mnt = kern_mount(&bd_type);
881 if (IS_ERR(bd_mnt))
882 panic("Cannot create bdev pseudo-fs");
883 blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */
884}
885
886struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
887{
888 struct block_device *bdev;
889 struct inode *inode;
890
891 inode = new_inode(blockdev_superblock);
892 if (!inode)
893 return NULL;
894 inode->i_mode = S_IFBLK;
895 inode->i_rdev = 0;
896 inode->i_data.a_ops = &def_blk_aops;
897 mapping_set_gfp_mask(&inode->i_data, GFP_USER);
898
899 bdev = I_BDEV(inode);
900 mutex_init(&bdev->bd_fsfreeze_mutex);
901 spin_lock_init(&bdev->bd_size_lock);
902 bdev->bd_disk = disk;
903 bdev->bd_partno = partno;
904 bdev->bd_inode = inode;
905#ifdef CONFIG_SYSFS
906 INIT_LIST_HEAD(&bdev->bd_holder_disks);
907#endif
908 bdev->bd_stats = alloc_percpu(struct disk_stats);
909 if (!bdev->bd_stats) {
910 iput(inode);
911 return NULL;
912 }
913 return bdev;
914}
915
916void bdev_add(struct block_device *bdev, dev_t dev)
917{
918 bdev->bd_dev = dev;
919 bdev->bd_inode->i_rdev = dev;
920 bdev->bd_inode->i_ino = dev;
921 insert_inode_hash(bdev->bd_inode);
922}
923
924static struct block_device *bdget(dev_t dev)
925{
926 struct inode *inode;
927
928 inode = ilookup(blockdev_superblock, dev);
929 if (!inode)
930 return NULL;
931 return &BDEV_I(inode)->bdev;
932}
933
934/**
935 * bdgrab -- Grab a reference to an already referenced block device
936 * @bdev: Block device to grab a reference to.
937 *
938 * Returns the block_device with an additional reference when successful,
939 * or NULL if the inode is already beeing freed.
940 */
941struct block_device *bdgrab(struct block_device *bdev)
942{
943 if (!igrab(bdev->bd_inode))
944 return NULL;
945 return bdev;
946}
947EXPORT_SYMBOL(bdgrab);
948
949long nr_blockdev_pages(void)
950{
951 struct inode *inode;
952 long ret = 0;
953
954 spin_lock(&blockdev_superblock->s_inode_list_lock);
955 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list)
956 ret += inode->i_mapping->nrpages;
957 spin_unlock(&blockdev_superblock->s_inode_list_lock);
958
959 return ret;
960}
961
962void bdput(struct block_device *bdev)
963{
964 iput(bdev->bd_inode);
965}
966EXPORT_SYMBOL(bdput);
967
968/**
969 * bd_may_claim - test whether a block device can be claimed
970 * @bdev: block device of interest
971 * @whole: whole block device containing @bdev, may equal @bdev
972 * @holder: holder trying to claim @bdev
973 *
974 * Test whether @bdev can be claimed by @holder.
975 *
976 * CONTEXT:
977 * spin_lock(&bdev_lock).
978 *
979 * RETURNS:
980 * %true if @bdev can be claimed, %false otherwise.
981 */
982static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
983 void *holder)
984{
985 if (bdev->bd_holder == holder)
986 return true; /* already a holder */
987 else if (bdev->bd_holder != NULL)
988 return false; /* held by someone else */
989 else if (whole == bdev)
990 return true; /* is a whole device which isn't held */
991
992 else if (whole->bd_holder == bd_may_claim)
993 return true; /* is a partition of a device that is being partitioned */
994 else if (whole->bd_holder != NULL)
995 return false; /* is a partition of a held device */
996 else
997 return true; /* is a partition of an un-held device */
998}
999
1000/**
1001 * bd_prepare_to_claim - claim a block device
1002 * @bdev: block device of interest
1003 * @holder: holder trying to claim @bdev
1004 *
1005 * Claim @bdev. This function fails if @bdev is already claimed by another
1006 * holder and waits if another claiming is in progress. return, the caller
1007 * has ownership of bd_claiming and bd_holder[s].
1008 *
1009 * RETURNS:
1010 * 0 if @bdev can be claimed, -EBUSY otherwise.
1011 */
1012int bd_prepare_to_claim(struct block_device *bdev, void *holder)
1013{
1014 struct block_device *whole = bdev_whole(bdev);
1015
1016 if (WARN_ON_ONCE(!holder))
1017 return -EINVAL;
1018retry:
1019 spin_lock(&bdev_lock);
1020 /* if someone else claimed, fail */
1021 if (!bd_may_claim(bdev, whole, holder)) {
1022 spin_unlock(&bdev_lock);
1023 return -EBUSY;
1024 }
1025
1026 /* if claiming is already in progress, wait for it to finish */
1027 if (whole->bd_claiming) {
1028 wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
1029 DEFINE_WAIT(wait);
1030
1031 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
1032 spin_unlock(&bdev_lock);
1033 schedule();
1034 finish_wait(wq, &wait);
1035 goto retry;
1036 }
1037
1038 /* yay, all mine */
1039 whole->bd_claiming = holder;
1040 spin_unlock(&bdev_lock);
1041 return 0;
1042}
1043EXPORT_SYMBOL_GPL(bd_prepare_to_claim); /* only for the loop driver */
1044
1045static void bd_clear_claiming(struct block_device *whole, void *holder)
1046{
1047 lockdep_assert_held(&bdev_lock);
1048 /* tell others that we're done */
1049 BUG_ON(whole->bd_claiming != holder);
1050 whole->bd_claiming = NULL;
1051 wake_up_bit(&whole->bd_claiming, 0);
1052}
1053
1054/**
1055 * bd_finish_claiming - finish claiming of a block device
1056 * @bdev: block device of interest
1057 * @holder: holder that has claimed @bdev
1058 *
1059 * Finish exclusive open of a block device. Mark the device as exlusively
1060 * open by the holder and wake up all waiters for exclusive open to finish.
1061 */
1062static void bd_finish_claiming(struct block_device *bdev, void *holder)
1063{
1064 struct block_device *whole = bdev_whole(bdev);
1065
1066 spin_lock(&bdev_lock);
1067 BUG_ON(!bd_may_claim(bdev, whole, holder));
1068 /*
1069 * Note that for a whole device bd_holders will be incremented twice,
1070 * and bd_holder will be set to bd_may_claim before being set to holder
1071 */
1072 whole->bd_holders++;
1073 whole->bd_holder = bd_may_claim;
1074 bdev->bd_holders++;
1075 bdev->bd_holder = holder;
1076 bd_clear_claiming(whole, holder);
1077 spin_unlock(&bdev_lock);
1078}
1079
1080/**
1081 * bd_abort_claiming - abort claiming of a block device
1082 * @bdev: block device of interest
1083 * @holder: holder that has claimed @bdev
1084 *
1085 * Abort claiming of a block device when the exclusive open failed. This can be
1086 * also used when exclusive open is not actually desired and we just needed
1087 * to block other exclusive openers for a while.
1088 */
1089void bd_abort_claiming(struct block_device *bdev, void *holder)
1090{
1091 spin_lock(&bdev_lock);
1092 bd_clear_claiming(bdev_whole(bdev), holder);
1093 spin_unlock(&bdev_lock);
1094}
1095EXPORT_SYMBOL(bd_abort_claiming);
1096
1097#ifdef CONFIG_SYSFS
1098struct bd_holder_disk {
1099 struct list_head list;
1100 struct gendisk *disk;
1101 int refcnt;
1102};
1103
1104static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
1105 struct gendisk *disk)
1106{
1107 struct bd_holder_disk *holder;
1108
1109 list_for_each_entry(holder, &bdev->bd_holder_disks, list)
1110 if (holder->disk == disk)
1111 return holder;
1112 return NULL;
1113}
1114
1115static int add_symlink(struct kobject *from, struct kobject *to)
1116{
1117 return sysfs_create_link(from, to, kobject_name(to));
1118}
1119
1120static void del_symlink(struct kobject *from, struct kobject *to)
1121{
1122 sysfs_remove_link(from, kobject_name(to));
1123}
1124
1125/**
1126 * bd_link_disk_holder - create symlinks between holding disk and slave bdev
1127 * @bdev: the claimed slave bdev
1128 * @disk: the holding disk
1129 *
1130 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
1131 *
1132 * This functions creates the following sysfs symlinks.
1133 *
1134 * - from "slaves" directory of the holder @disk to the claimed @bdev
1135 * - from "holders" directory of the @bdev to the holder @disk
1136 *
1137 * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
1138 * passed to bd_link_disk_holder(), then:
1139 *
1140 * /sys/block/dm-0/slaves/sda --> /sys/block/sda
1141 * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
1142 *
1143 * The caller must have claimed @bdev before calling this function and
1144 * ensure that both @bdev and @disk are valid during the creation and
1145 * lifetime of these symlinks.
1146 *
1147 * CONTEXT:
1148 * Might sleep.
1149 *
1150 * RETURNS:
1151 * 0 on success, -errno on failure.
1152 */
1153int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
1154{
1155 struct bd_holder_disk *holder;
1156 int ret = 0;
1157
1158 mutex_lock(&bdev->bd_disk->open_mutex);
1159
1160 WARN_ON_ONCE(!bdev->bd_holder);
1161
1162 /* FIXME: remove the following once add_disk() handles errors */
1163 if (WARN_ON(!disk->slave_dir || !bdev->bd_holder_dir))
1164 goto out_unlock;
1165
1166 holder = bd_find_holder_disk(bdev, disk);
1167 if (holder) {
1168 holder->refcnt++;
1169 goto out_unlock;
1170 }
1171
1172 holder = kzalloc(sizeof(*holder), GFP_KERNEL);
1173 if (!holder) {
1174 ret = -ENOMEM;
1175 goto out_unlock;
1176 }
1177
1178 INIT_LIST_HEAD(&holder->list);
1179 holder->disk = disk;
1180 holder->refcnt = 1;
1181
1182 ret = add_symlink(disk->slave_dir, bdev_kobj(bdev));
1183 if (ret)
1184 goto out_free;
1185
1186 ret = add_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
1187 if (ret)
1188 goto out_del;
1189 /*
1190 * bdev could be deleted beneath us which would implicitly destroy
1191 * the holder directory. Hold on to it.
1192 */
1193 kobject_get(bdev->bd_holder_dir);
1194
1195 list_add(&holder->list, &bdev->bd_holder_disks);
1196 goto out_unlock;
1197
1198out_del:
1199 del_symlink(disk->slave_dir, bdev_kobj(bdev));
1200out_free:
1201 kfree(holder);
1202out_unlock:
1203 mutex_unlock(&bdev->bd_disk->open_mutex);
1204 return ret;
1205}
1206EXPORT_SYMBOL_GPL(bd_link_disk_holder);
1207
1208/**
1209 * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
1210 * @bdev: the calimed slave bdev
1211 * @disk: the holding disk
1212 *
1213 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
1214 *
1215 * CONTEXT:
1216 * Might sleep.
1217 */
1218void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
1219{
1220 struct bd_holder_disk *holder;
1221
1222 mutex_lock(&bdev->bd_disk->open_mutex);
1223
1224 holder = bd_find_holder_disk(bdev, disk);
1225
1226 if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
1227 del_symlink(disk->slave_dir, bdev_kobj(bdev));
1228 del_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
1229 kobject_put(bdev->bd_holder_dir);
1230 list_del_init(&holder->list);
1231 kfree(holder);
1232 }
1233
1234 mutex_unlock(&bdev->bd_disk->open_mutex);
1235}
1236EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
1237#endif
1238
1239static void blkdev_flush_mapping(struct block_device *bdev)
1240{
1241 WARN_ON_ONCE(bdev->bd_holders);
1242 sync_blockdev(bdev);
1243 kill_bdev(bdev);
1244 bdev_write_inode(bdev);
1245}
1246
1247static int blkdev_get_whole(struct block_device *bdev, fmode_t mode)
1248{
1249 struct gendisk *disk = bdev->bd_disk;
1250 int ret = 0;
1251
1252 if (disk->fops->open) {
1253 ret = disk->fops->open(bdev, mode);
1254 if (ret) {
1255 /* avoid ghost partitions on a removed medium */
1256 if (ret == -ENOMEDIUM &&
1257 test_bit(GD_NEED_PART_SCAN, &disk->state))
1258 bdev_disk_changed(disk, true);
1259 return ret;
1260 }
1261 }
1262
1263 if (!bdev->bd_openers) {
1264 set_init_blocksize(bdev);
1265 if (bdev->bd_bdi == &noop_backing_dev_info)
1266 bdev->bd_bdi = bdi_get(disk->queue->backing_dev_info);
1267 }
1268 if (test_bit(GD_NEED_PART_SCAN, &disk->state))
1269 bdev_disk_changed(disk, false);
1270 bdev->bd_openers++;
1271 return 0;;
1272}
1273
1274static void blkdev_put_whole(struct block_device *bdev, fmode_t mode)
1275{
1276 if (!--bdev->bd_openers)
1277 blkdev_flush_mapping(bdev);
1278 if (bdev->bd_disk->fops->release)
1279 bdev->bd_disk->fops->release(bdev->bd_disk, mode);
1280}
1281
1282static int blkdev_get_part(struct block_device *part, fmode_t mode)
1283{
1284 struct gendisk *disk = part->bd_disk;
1285 struct block_device *whole;
1286 int ret;
1287
1288 if (part->bd_openers)
1289 goto done;
1290
1291 whole = bdgrab(disk->part0);
1292 ret = blkdev_get_whole(whole, mode);
1293 if (ret)
1294 goto out_put_whole;
1295
1296 ret = -ENXIO;
1297 if (!bdev_nr_sectors(part))
1298 goto out_blkdev_put;
1299
1300 disk->open_partitions++;
1301 set_init_blocksize(part);
1302 if (part->bd_bdi == &noop_backing_dev_info)
1303 part->bd_bdi = bdi_get(disk->queue->backing_dev_info);
1304done:
1305 part->bd_openers++;
1306 return 0;
1307
1308out_blkdev_put:
1309 blkdev_put_whole(whole, mode);
1310out_put_whole:
1311 bdput(whole);
1312 return ret;
1313}
1314
1315static void blkdev_put_part(struct block_device *part, fmode_t mode)
1316{
1317 struct block_device *whole = bdev_whole(part);
1318
1319 if (--part->bd_openers)
1320 return;
1321 blkdev_flush_mapping(part);
1322 whole->bd_disk->open_partitions--;
1323 blkdev_put_whole(whole, mode);
1324 bdput(whole);
1325}
1326
1327struct block_device *blkdev_get_no_open(dev_t dev)
1328{
1329 struct block_device *bdev;
1330 struct gendisk *disk;
1331
1332 bdev = bdget(dev);
1333 if (!bdev) {
1334 blk_request_module(dev);
1335 bdev = bdget(dev);
1336 if (!bdev)
1337 return NULL;
1338 }
1339
1340 disk = bdev->bd_disk;
1341 if (!kobject_get_unless_zero(&disk_to_dev(disk)->kobj))
1342 goto bdput;
1343 if ((disk->flags & (GENHD_FL_UP | GENHD_FL_HIDDEN)) != GENHD_FL_UP)
1344 goto put_disk;
1345 if (!try_module_get(bdev->bd_disk->fops->owner))
1346 goto put_disk;
1347 return bdev;
1348put_disk:
1349 put_disk(disk);
1350bdput:
1351 bdput(bdev);
1352 return NULL;
1353}
1354
1355void blkdev_put_no_open(struct block_device *bdev)
1356{
1357 module_put(bdev->bd_disk->fops->owner);
1358 put_disk(bdev->bd_disk);
1359 bdput(bdev);
1360}
1361
1362/**
1363 * blkdev_get_by_dev - open a block device by device number
1364 * @dev: device number of block device to open
1365 * @mode: FMODE_* mask
1366 * @holder: exclusive holder identifier
1367 *
1368 * Open the block device described by device number @dev. If @mode includes
1369 * %FMODE_EXCL, the block device is opened with exclusive access. Specifying
1370 * %FMODE_EXCL with a %NULL @holder is invalid. Exclusive opens may nest for
1371 * the same @holder.
1372 *
1373 * Use this interface ONLY if you really do not have anything better - i.e. when
1374 * you are behind a truly sucky interface and all you are given is a device
1375 * number. Everything else should use blkdev_get_by_path().
1376 *
1377 * CONTEXT:
1378 * Might sleep.
1379 *
1380 * RETURNS:
1381 * Reference to the block_device on success, ERR_PTR(-errno) on failure.
1382 */
1383struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
1384{
1385 bool unblock_events = true;
1386 struct block_device *bdev;
1387 struct gendisk *disk;
1388 int ret;
1389
1390 ret = devcgroup_check_permission(DEVCG_DEV_BLOCK,
1391 MAJOR(dev), MINOR(dev),
1392 ((mode & FMODE_READ) ? DEVCG_ACC_READ : 0) |
1393 ((mode & FMODE_WRITE) ? DEVCG_ACC_WRITE : 0));
1394 if (ret)
1395 return ERR_PTR(ret);
1396
1397 bdev = blkdev_get_no_open(dev);
1398 if (!bdev)
1399 return ERR_PTR(-ENXIO);
1400 disk = bdev->bd_disk;
1401
1402 if (mode & FMODE_EXCL) {
1403 ret = bd_prepare_to_claim(bdev, holder);
1404 if (ret)
1405 goto put_blkdev;
1406 }
1407
1408 disk_block_events(disk);
1409
1410 mutex_lock(&disk->open_mutex);
1411 ret = -ENXIO;
1412 if (!(disk->flags & GENHD_FL_UP))
1413 goto abort_claiming;
1414 if (bdev_is_partition(bdev))
1415 ret = blkdev_get_part(bdev, mode);
1416 else
1417 ret = blkdev_get_whole(bdev, mode);
1418 if (ret)
1419 goto abort_claiming;
1420 if (mode & FMODE_EXCL) {
1421 bd_finish_claiming(bdev, holder);
1422
1423 /*
1424 * Block event polling for write claims if requested. Any write
1425 * holder makes the write_holder state stick until all are
1426 * released. This is good enough and tracking individual
1427 * writeable reference is too fragile given the way @mode is
1428 * used in blkdev_get/put().
1429 */
1430 if ((mode & FMODE_WRITE) && !bdev->bd_write_holder &&
1431 (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
1432 bdev->bd_write_holder = true;
1433 unblock_events = false;
1434 }
1435 }
1436 mutex_unlock(&disk->open_mutex);
1437
1438 if (unblock_events)
1439 disk_unblock_events(disk);
1440 return bdev;
1441
1442abort_claiming:
1443 if (mode & FMODE_EXCL)
1444 bd_abort_claiming(bdev, holder);
1445 mutex_unlock(&disk->open_mutex);
1446 disk_unblock_events(disk);
1447put_blkdev:
1448 blkdev_put_no_open(bdev);
1449 return ERR_PTR(ret);
1450}
1451EXPORT_SYMBOL(blkdev_get_by_dev);
1452
1453/**
1454 * blkdev_get_by_path - open a block device by name
1455 * @path: path to the block device to open
1456 * @mode: FMODE_* mask
1457 * @holder: exclusive holder identifier
1458 *
1459 * Open the block device described by the device file at @path. If @mode
1460 * includes %FMODE_EXCL, the block device is opened with exclusive access.
1461 * Specifying %FMODE_EXCL with a %NULL @holder is invalid. Exclusive opens may
1462 * nest for the same @holder.
1463 *
1464 * CONTEXT:
1465 * Might sleep.
1466 *
1467 * RETURNS:
1468 * Reference to the block_device on success, ERR_PTR(-errno) on failure.
1469 */
1470struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
1471 void *holder)
1472{
1473 struct block_device *bdev;
1474 dev_t dev;
1475 int error;
1476
1477 error = lookup_bdev(path, &dev);
1478 if (error)
1479 return ERR_PTR(error);
1480
1481 bdev = blkdev_get_by_dev(dev, mode, holder);
1482 if (!IS_ERR(bdev) && (mode & FMODE_WRITE) && bdev_read_only(bdev)) {
1483 blkdev_put(bdev, mode);
1484 return ERR_PTR(-EACCES);
1485 }
1486
1487 return bdev;
1488}
1489EXPORT_SYMBOL(blkdev_get_by_path);
1490
1491static int blkdev_open(struct inode * inode, struct file * filp)
1492{
1493 struct block_device *bdev;
1494
1495 /*
1496 * Preserve backwards compatibility and allow large file access
1497 * even if userspace doesn't ask for it explicitly. Some mkfs
1498 * binary needs it. We might want to drop this workaround
1499 * during an unstable branch.
1500 */
1501 filp->f_flags |= O_LARGEFILE;
1502
1503 filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
1504
1505 if (filp->f_flags & O_NDELAY)
1506 filp->f_mode |= FMODE_NDELAY;
1507 if (filp->f_flags & O_EXCL)
1508 filp->f_mode |= FMODE_EXCL;
1509 if ((filp->f_flags & O_ACCMODE) == 3)
1510 filp->f_mode |= FMODE_WRITE_IOCTL;
1511
1512 bdev = blkdev_get_by_dev(inode->i_rdev, filp->f_mode, filp);
1513 if (IS_ERR(bdev))
1514 return PTR_ERR(bdev);
1515 filp->f_mapping = bdev->bd_inode->i_mapping;
1516 filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
1517 return 0;
1518}
1519
1520void blkdev_put(struct block_device *bdev, fmode_t mode)
1521{
1522 struct gendisk *disk = bdev->bd_disk;
1523
1524 /*
1525 * Sync early if it looks like we're the last one. If someone else
1526 * opens the block device between now and the decrement of bd_openers
1527 * then we did a sync that we didn't need to, but that's not the end
1528 * of the world and we want to avoid long (could be several minute)
1529 * syncs while holding the mutex.
1530 */
1531 if (bdev->bd_openers == 1)
1532 sync_blockdev(bdev);
1533
1534 mutex_lock(&disk->open_mutex);
1535 if (mode & FMODE_EXCL) {
1536 struct block_device *whole = bdev_whole(bdev);
1537 bool bdev_free;
1538
1539 /*
1540 * Release a claim on the device. The holder fields
1541 * are protected with bdev_lock. open_mutex is to
1542 * synchronize disk_holder unlinking.
1543 */
1544 spin_lock(&bdev_lock);
1545
1546 WARN_ON_ONCE(--bdev->bd_holders < 0);
1547 WARN_ON_ONCE(--whole->bd_holders < 0);
1548
1549 if ((bdev_free = !bdev->bd_holders))
1550 bdev->bd_holder = NULL;
1551 if (!whole->bd_holders)
1552 whole->bd_holder = NULL;
1553
1554 spin_unlock(&bdev_lock);
1555
1556 /*
1557 * If this was the last claim, remove holder link and
1558 * unblock evpoll if it was a write holder.
1559 */
1560 if (bdev_free && bdev->bd_write_holder) {
1561 disk_unblock_events(disk);
1562 bdev->bd_write_holder = false;
1563 }
1564 }
1565
1566 /*
1567 * Trigger event checking and tell drivers to flush MEDIA_CHANGE
1568 * event. This is to ensure detection of media removal commanded
1569 * from userland - e.g. eject(1).
1570 */
1571 disk_flush_events(disk, DISK_EVENT_MEDIA_CHANGE);
1572
1573 if (bdev_is_partition(bdev))
1574 blkdev_put_part(bdev, mode);
1575 else
1576 blkdev_put_whole(bdev, mode);
1577 mutex_unlock(&disk->open_mutex);
1578
1579 blkdev_put_no_open(bdev);
1580}
1581EXPORT_SYMBOL(blkdev_put);
1582
1583static int blkdev_close(struct inode * inode, struct file * filp)
1584{
1585 struct block_device *bdev = I_BDEV(bdev_file_inode(filp));
1586 blkdev_put(bdev, filp->f_mode);
1587 return 0;
1588}
1589
1590static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
1591{
1592 struct block_device *bdev = I_BDEV(bdev_file_inode(file));
1593 fmode_t mode = file->f_mode;
1594
1595 /*
1596 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
1597 * to updated it before every ioctl.
1598 */
1599 if (file->f_flags & O_NDELAY)
1600 mode |= FMODE_NDELAY;
1601 else
1602 mode &= ~FMODE_NDELAY;
1603
1604 return blkdev_ioctl(bdev, mode, cmd, arg);
1605}
1606
1607/*
1608 * Write data to the block device. Only intended for the block device itself
1609 * and the raw driver which basically is a fake block device.
1610 *
1611 * Does not take i_mutex for the write and thus is not for general purpose
1612 * use.
1613 */
1614static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
1615{
1616 struct file *file = iocb->ki_filp;
1617 struct inode *bd_inode = bdev_file_inode(file);
1618 loff_t size = i_size_read(bd_inode);
1619 struct blk_plug plug;
1620 size_t shorted = 0;
1621 ssize_t ret;
1622
1623 if (bdev_read_only(I_BDEV(bd_inode)))
1624 return -EPERM;
1625
1626 if (IS_SWAPFILE(bd_inode) && !is_hibernate_resume_dev(bd_inode->i_rdev))
1627 return -ETXTBSY;
1628
1629 if (!iov_iter_count(from))
1630 return 0;
1631
1632 if (iocb->ki_pos >= size)
1633 return -ENOSPC;
1634
1635 if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
1636 return -EOPNOTSUPP;
1637
1638 size -= iocb->ki_pos;
1639 if (iov_iter_count(from) > size) {
1640 shorted = iov_iter_count(from) - size;
1641 iov_iter_truncate(from, size);
1642 }
1643
1644 blk_start_plug(&plug);
1645 ret = __generic_file_write_iter(iocb, from);
1646 if (ret > 0)
1647 ret = generic_write_sync(iocb, ret);
1648 iov_iter_reexpand(from, iov_iter_count(from) + shorted);
1649 blk_finish_plug(&plug);
1650 return ret;
1651}
1652
1653static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
1654{
1655 struct file *file = iocb->ki_filp;
1656 struct inode *bd_inode = bdev_file_inode(file);
1657 loff_t size = i_size_read(bd_inode);
1658 loff_t pos = iocb->ki_pos;
1659 size_t shorted = 0;
1660 ssize_t ret;
1661
1662 if (pos >= size)
1663 return 0;
1664
1665 size -= pos;
1666 if (iov_iter_count(to) > size) {
1667 shorted = iov_iter_count(to) - size;
1668 iov_iter_truncate(to, size);
1669 }
1670
1671 ret = generic_file_read_iter(iocb, to);
1672 iov_iter_reexpand(to, iov_iter_count(to) + shorted);
1673 return ret;
1674}
1675
1676static int blkdev_writepages(struct address_space *mapping,
1677 struct writeback_control *wbc)
1678{
1679 return generic_writepages(mapping, wbc);
1680}
1681
1682static const struct address_space_operations def_blk_aops = {
1683 .set_page_dirty = __set_page_dirty_buffers,
1684 .readpage = blkdev_readpage,
1685 .readahead = blkdev_readahead,
1686 .writepage = blkdev_writepage,
1687 .write_begin = blkdev_write_begin,
1688 .write_end = blkdev_write_end,
1689 .writepages = blkdev_writepages,
1690 .direct_IO = blkdev_direct_IO,
1691 .migratepage = buffer_migrate_page_norefs,
1692 .is_dirty_writeback = buffer_check_dirty_writeback,
1693};
1694
1695#define BLKDEV_FALLOC_FL_SUPPORTED \
1696 (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | \
1697 FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE)
1698
1699static long blkdev_fallocate(struct file *file, int mode, loff_t start,
1700 loff_t len)
1701{
1702 struct block_device *bdev = I_BDEV(bdev_file_inode(file));
1703 loff_t end = start + len - 1;
1704 loff_t isize;
1705 int error;
1706
1707 /* Fail if we don't recognize the flags. */
1708 if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
1709 return -EOPNOTSUPP;
1710
1711 /* Don't go off the end of the device. */
1712 isize = i_size_read(bdev->bd_inode);
1713 if (start >= isize)
1714 return -EINVAL;
1715 if (end >= isize) {
1716 if (mode & FALLOC_FL_KEEP_SIZE) {
1717 len = isize - start;
1718 end = start + len - 1;
1719 } else
1720 return -EINVAL;
1721 }
1722
1723 /*
1724 * Don't allow IO that isn't aligned to logical block size.
1725 */
1726 if ((start | len) & (bdev_logical_block_size(bdev) - 1))
1727 return -EINVAL;
1728
1729 /* Invalidate the page cache, including dirty pages. */
1730 error = truncate_bdev_range(bdev, file->f_mode, start, end);
1731 if (error)
1732 return error;
1733
1734 switch (mode) {
1735 case FALLOC_FL_ZERO_RANGE:
1736 case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
1737 error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
1738 GFP_KERNEL, BLKDEV_ZERO_NOUNMAP);
1739 break;
1740 case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
1741 error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
1742 GFP_KERNEL, BLKDEV_ZERO_NOFALLBACK);
1743 break;
1744 case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
1745 error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
1746 GFP_KERNEL, 0);
1747 break;
1748 default:
1749 return -EOPNOTSUPP;
1750 }
1751 if (error)
1752 return error;
1753
1754 /*
1755 * Invalidate the page cache again; if someone wandered in and dirtied
1756 * a page, we just discard it - userspace has no way of knowing whether
1757 * the write happened before or after discard completing...
1758 */
1759 return truncate_bdev_range(bdev, file->f_mode, start, end);
1760}
1761
1762const struct file_operations def_blk_fops = {
1763 .open = blkdev_open,
1764 .release = blkdev_close,
1765 .llseek = block_llseek,
1766 .read_iter = blkdev_read_iter,
1767 .write_iter = blkdev_write_iter,
1768 .iopoll = blkdev_iopoll,
1769 .mmap = generic_file_mmap,
1770 .fsync = blkdev_fsync,
1771 .unlocked_ioctl = block_ioctl,
1772#ifdef CONFIG_COMPAT
1773 .compat_ioctl = compat_blkdev_ioctl,
1774#endif
1775 .splice_read = generic_file_splice_read,
1776 .splice_write = iter_file_splice_write,
1777 .fallocate = blkdev_fallocate,
1778};
1779
1780/**
1781 * lookup_bdev - lookup a struct block_device by name
1782 * @pathname: special file representing the block device
1783 * @dev: return value of the block device's dev_t
1784 *
1785 * Get a reference to the blockdevice at @pathname in the current
1786 * namespace if possible and return it. Return ERR_PTR(error)
1787 * otherwise.
1788 */
1789int lookup_bdev(const char *pathname, dev_t *dev)
1790{
1791 struct inode *inode;
1792 struct path path;
1793 int error;
1794
1795 if (!pathname || !*pathname)
1796 return -EINVAL;
1797
1798 error = kern_path(pathname, LOOKUP_FOLLOW, &path);
1799 if (error)
1800 return error;
1801
1802 inode = d_backing_inode(path.dentry);
1803 error = -ENOTBLK;
1804 if (!S_ISBLK(inode->i_mode))
1805 goto out_path_put;
1806 error = -EACCES;
1807 if (!may_open_dev(&path))
1808 goto out_path_put;
1809
1810 *dev = inode->i_rdev;
1811 error = 0;
1812out_path_put:
1813 path_put(&path);
1814 return error;
1815}
1816EXPORT_SYMBOL(lookup_bdev);
1817
1818int __invalidate_device(struct block_device *bdev, bool kill_dirty)
1819{
1820 struct super_block *sb = get_super(bdev);
1821 int res = 0;
1822
1823 if (sb) {
1824 /*
1825 * no need to lock the super, get_super holds the
1826 * read mutex so the filesystem cannot go away
1827 * under us (->put_super runs with the write lock
1828 * hold).
1829 */
1830 shrink_dcache_sb(sb);
1831 res = invalidate_inodes(sb, kill_dirty);
1832 drop_super(sb);
1833 }
1834 invalidate_bdev(bdev);
1835 return res;
1836}
1837EXPORT_SYMBOL(__invalidate_device);
1838
1839void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
1840{
1841 struct inode *inode, *old_inode = NULL;
1842
1843 spin_lock(&blockdev_superblock->s_inode_list_lock);
1844 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
1845 struct address_space *mapping = inode->i_mapping;
1846 struct block_device *bdev;
1847
1848 spin_lock(&inode->i_lock);
1849 if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
1850 mapping->nrpages == 0) {
1851 spin_unlock(&inode->i_lock);
1852 continue;
1853 }
1854 __iget(inode);
1855 spin_unlock(&inode->i_lock);
1856 spin_unlock(&blockdev_superblock->s_inode_list_lock);
1857 /*
1858 * We hold a reference to 'inode' so it couldn't have been
1859 * removed from s_inodes list while we dropped the
1860 * s_inode_list_lock We cannot iput the inode now as we can
1861 * be holding the last reference and we cannot iput it under
1862 * s_inode_list_lock. So we keep the reference and iput it
1863 * later.
1864 */
1865 iput(old_inode);
1866 old_inode = inode;
1867 bdev = I_BDEV(inode);
1868
1869 mutex_lock(&bdev->bd_disk->open_mutex);
1870 if (bdev->bd_openers)
1871 func(bdev, arg);
1872 mutex_unlock(&bdev->bd_disk->open_mutex);
1873
1874 spin_lock(&blockdev_superblock->s_inode_list_lock);
1875 }
1876 spin_unlock(&blockdev_superblock->s_inode_list_lock);
1877 iput(old_inode);
1878}