projects/linux·blob v5.16 · refs

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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 <[email protected]> SuSE
5 * Copyright (C) 2016 - 2020 Christoph Hellwig
6 */
7
8#include <linux/init.h>
9#include <linux/mm.h>
10#include <linux/slab.h>
11#include <linux/kmod.h>
12#include <linux/major.h>
13#include <linux/device_cgroup.h>
14#include <linux/blkdev.h>
15#include <linux/blk-integrity.h>
16#include <linux/backing-dev.h>
17#include <linux/module.h>
18#include <linux/blkpg.h>
19#include <linux/magic.h>
20#include <linux/buffer_head.h>
21#include <linux/swap.h>
22#include <linux/writeback.h>
23#include <linux/mount.h>
24#include <linux/pseudo_fs.h>
25#include <linux/uio.h>
26#include <linux/namei.h>
27#include <linux/cleancache.h>
28#include <linux/part_stat.h>
29#include <linux/uaccess.h>
30#include "../fs/internal.h"
31#include "blk.h"
32
33struct bdev_inode {
34 struct block_device bdev;
35 struct inode vfs_inode;
36};
37
38static inline struct bdev_inode *BDEV_I(struct inode *inode)
39{
40 return container_of(inode, struct bdev_inode, vfs_inode);
41}
42
43struct block_device *I_BDEV(struct inode *inode)
44{
45 return &BDEV_I(inode)->bdev;
46}
47EXPORT_SYMBOL(I_BDEV);
48
49static void bdev_write_inode(struct block_device *bdev)
50{
51 struct inode *inode = bdev->bd_inode;
52 int ret;
53
54 spin_lock(&inode->i_lock);
55 while (inode->i_state & I_DIRTY) {
56 spin_unlock(&inode->i_lock);
57 ret = write_inode_now(inode, true);
58 if (ret) {
59 char name[BDEVNAME_SIZE];
60 pr_warn_ratelimited("VFS: Dirty inode writeback failed "
61 "for block device %s (err=%d).\n",
62 bdevname(bdev, name), ret);
63 }
64 spin_lock(&inode->i_lock);
65 }
66 spin_unlock(&inode->i_lock);
67}
68
69/* Kill _all_ buffers and pagecache , dirty or not.. */
70static void kill_bdev(struct block_device *bdev)
71{
72 struct address_space *mapping = bdev->bd_inode->i_mapping;
73
74 if (mapping_empty(mapping))
75 return;
76
77 invalidate_bh_lrus();
78 truncate_inode_pages(mapping, 0);
79}
80
81/* Invalidate clean unused buffers and pagecache. */
82void invalidate_bdev(struct block_device *bdev)
83{
84 struct address_space *mapping = bdev->bd_inode->i_mapping;
85
86 if (mapping->nrpages) {
87 invalidate_bh_lrus();
88 lru_add_drain_all(); /* make sure all lru add caches are flushed */
89 invalidate_mapping_pages(mapping, 0, -1);
90 }
91 /* 99% of the time, we don't need to flush the cleancache on the bdev.
92 * But, for the strange corners, lets be cautious
93 */
94 cleancache_invalidate_inode(mapping);
95}
96EXPORT_SYMBOL(invalidate_bdev);
97
98/*
99 * Drop all buffers & page cache for given bdev range. This function bails
100 * with error if bdev has other exclusive owner (such as filesystem).
101 */
102int truncate_bdev_range(struct block_device *bdev, fmode_t mode,
103 loff_t lstart, loff_t lend)
104{
105 /*
106 * If we don't hold exclusive handle for the device, upgrade to it
107 * while we discard the buffer cache to avoid discarding buffers
108 * under live filesystem.
109 */
110 if (!(mode & FMODE_EXCL)) {
111 int err = bd_prepare_to_claim(bdev, truncate_bdev_range);
112 if (err)
113 goto invalidate;
114 }
115
116 truncate_inode_pages_range(bdev->bd_inode->i_mapping, lstart, lend);
117 if (!(mode & FMODE_EXCL))
118 bd_abort_claiming(bdev, truncate_bdev_range);
119 return 0;
120
121invalidate:
122 /*
123 * Someone else has handle exclusively open. Try invalidating instead.
124 * The 'end' argument is inclusive so the rounding is safe.
125 */
126 return invalidate_inode_pages2_range(bdev->bd_inode->i_mapping,
127 lstart >> PAGE_SHIFT,
128 lend >> PAGE_SHIFT);
129}
130
131static void set_init_blocksize(struct block_device *bdev)
132{
133 unsigned int bsize = bdev_logical_block_size(bdev);
134 loff_t size = i_size_read(bdev->bd_inode);
135
136 while (bsize < PAGE_SIZE) {
137 if (size & bsize)
138 break;
139 bsize <<= 1;
140 }
141 bdev->bd_inode->i_blkbits = blksize_bits(bsize);
142}
143
144int set_blocksize(struct block_device *bdev, int size)
145{
146 /* Size must be a power of two, and between 512 and PAGE_SIZE */
147 if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
148 return -EINVAL;
149
150 /* Size cannot be smaller than the size supported by the device */
151 if (size < bdev_logical_block_size(bdev))
152 return -EINVAL;
153
154 /* Don't change the size if it is same as current */
155 if (bdev->bd_inode->i_blkbits != blksize_bits(size)) {
156 sync_blockdev(bdev);
157 bdev->bd_inode->i_blkbits = blksize_bits(size);
158 kill_bdev(bdev);
159 }
160 return 0;
161}
162
163EXPORT_SYMBOL(set_blocksize);
164
165int sb_set_blocksize(struct super_block *sb, int size)
166{
167 if (set_blocksize(sb->s_bdev, size))
168 return 0;
169 /* If we get here, we know size is power of two
170 * and it's value is between 512 and PAGE_SIZE */
171 sb->s_blocksize = size;
172 sb->s_blocksize_bits = blksize_bits(size);
173 return sb->s_blocksize;
174}
175
176EXPORT_SYMBOL(sb_set_blocksize);
177
178int sb_min_blocksize(struct super_block *sb, int size)
179{
180 int minsize = bdev_logical_block_size(sb->s_bdev);
181 if (size < minsize)
182 size = minsize;
183 return sb_set_blocksize(sb, size);
184}
185
186EXPORT_SYMBOL(sb_min_blocksize);
187
188int sync_blockdev_nowait(struct block_device *bdev)
189{
190 if (!bdev)
191 return 0;
192 return filemap_flush(bdev->bd_inode->i_mapping);
193}
194EXPORT_SYMBOL_GPL(sync_blockdev_nowait);
195
196/*
197 * Write out and wait upon all the dirty data associated with a block
198 * device via its mapping. Does not take the superblock lock.
199 */
200int sync_blockdev(struct block_device *bdev)
201{
202 if (!bdev)
203 return 0;
204 return filemap_write_and_wait(bdev->bd_inode->i_mapping);
205}
206EXPORT_SYMBOL(sync_blockdev);
207
208/*
209 * Write out and wait upon all dirty data associated with this
210 * device. Filesystem data as well as the underlying block
211 * device. Takes the superblock lock.
212 */
213int fsync_bdev(struct block_device *bdev)
214{
215 struct super_block *sb = get_super(bdev);
216 if (sb) {
217 int res = sync_filesystem(sb);
218 drop_super(sb);
219 return res;
220 }
221 return sync_blockdev(bdev);
222}
223EXPORT_SYMBOL(fsync_bdev);
224
225/**
226 * freeze_bdev -- lock a filesystem and force it into a consistent state
227 * @bdev: blockdevice to lock
228 *
229 * If a superblock is found on this device, we take the s_umount semaphore
230 * on it to make sure nobody unmounts until the snapshot creation is done.
231 * The reference counter (bd_fsfreeze_count) guarantees that only the last
232 * unfreeze process can unfreeze the frozen filesystem actually when multiple
233 * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
234 * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
235 * actually.
236 */
237int freeze_bdev(struct block_device *bdev)
238{
239 struct super_block *sb;
240 int error = 0;
241
242 mutex_lock(&bdev->bd_fsfreeze_mutex);
243 if (++bdev->bd_fsfreeze_count > 1)
244 goto done;
245
246 sb = get_active_super(bdev);
247 if (!sb)
248 goto sync;
249 if (sb->s_op->freeze_super)
250 error = sb->s_op->freeze_super(sb);
251 else
252 error = freeze_super(sb);
253 deactivate_super(sb);
254
255 if (error) {
256 bdev->bd_fsfreeze_count--;
257 goto done;
258 }
259 bdev->bd_fsfreeze_sb = sb;
260
261sync:
262 sync_blockdev(bdev);
263done:
264 mutex_unlock(&bdev->bd_fsfreeze_mutex);
265 return error;
266}
267EXPORT_SYMBOL(freeze_bdev);
268
269/**
270 * thaw_bdev -- unlock filesystem
271 * @bdev: blockdevice to unlock
272 *
273 * Unlocks the filesystem and marks it writeable again after freeze_bdev().
274 */
275int thaw_bdev(struct block_device *bdev)
276{
277 struct super_block *sb;
278 int error = -EINVAL;
279
280 mutex_lock(&bdev->bd_fsfreeze_mutex);
281 if (!bdev->bd_fsfreeze_count)
282 goto out;
283
284 error = 0;
285 if (--bdev->bd_fsfreeze_count > 0)
286 goto out;
287
288 sb = bdev->bd_fsfreeze_sb;
289 if (!sb)
290 goto out;
291
292 if (sb->s_op->thaw_super)
293 error = sb->s_op->thaw_super(sb);
294 else
295 error = thaw_super(sb);
296 if (error)
297 bdev->bd_fsfreeze_count++;
298 else
299 bdev->bd_fsfreeze_sb = NULL;
300out:
301 mutex_unlock(&bdev->bd_fsfreeze_mutex);
302 return error;
303}
304EXPORT_SYMBOL(thaw_bdev);
305
306/**
307 * bdev_read_page() - Start reading a page from a block device
308 * @bdev: The device to read the page from
309 * @sector: The offset on the device to read the page to (need not be aligned)
310 * @page: The page to read
311 *
312 * On entry, the page should be locked. It will be unlocked when the page
313 * has been read. If the block driver implements rw_page synchronously,
314 * that will be true on exit from this function, but it need not be.
315 *
316 * Errors returned by this function are usually "soft", eg out of memory, or
317 * queue full; callers should try a different route to read this page rather
318 * than propagate an error back up the stack.
319 *
320 * Return: negative errno if an error occurs, 0 if submission was successful.
321 */
322int bdev_read_page(struct block_device *bdev, sector_t sector,
323 struct page *page)
324{
325 const struct block_device_operations *ops = bdev->bd_disk->fops;
326 int result = -EOPNOTSUPP;
327
328 if (!ops->rw_page || bdev_get_integrity(bdev))
329 return result;
330
331 result = blk_queue_enter(bdev_get_queue(bdev), 0);
332 if (result)
333 return result;
334 result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
335 REQ_OP_READ);
336 blk_queue_exit(bdev_get_queue(bdev));
337 return result;
338}
339
340/**
341 * bdev_write_page() - Start writing a page to a block device
342 * @bdev: The device to write the page to
343 * @sector: The offset on the device to write the page to (need not be aligned)
344 * @page: The page to write
345 * @wbc: The writeback_control for the write
346 *
347 * On entry, the page should be locked and not currently under writeback.
348 * On exit, if the write started successfully, the page will be unlocked and
349 * under writeback. If the write failed already (eg the driver failed to
350 * queue the page to the device), the page will still be locked. If the
351 * caller is a ->writepage implementation, it will need to unlock the page.
352 *
353 * Errors returned by this function are usually "soft", eg out of memory, or
354 * queue full; callers should try a different route to write this page rather
355 * than propagate an error back up the stack.
356 *
357 * Return: negative errno if an error occurs, 0 if submission was successful.
358 */
359int bdev_write_page(struct block_device *bdev, sector_t sector,
360 struct page *page, struct writeback_control *wbc)
361{
362 int result;
363 const struct block_device_operations *ops = bdev->bd_disk->fops;
364
365 if (!ops->rw_page || bdev_get_integrity(bdev))
366 return -EOPNOTSUPP;
367 result = blk_queue_enter(bdev_get_queue(bdev), 0);
368 if (result)
369 return result;
370
371 set_page_writeback(page);
372 result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
373 REQ_OP_WRITE);
374 if (result) {
375 end_page_writeback(page);
376 } else {
377 clean_page_buffers(page);
378 unlock_page(page);
379 }
380 blk_queue_exit(bdev_get_queue(bdev));
381 return result;
382}
383
384/*
385 * pseudo-fs
386 */
387
388static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
389static struct kmem_cache * bdev_cachep __read_mostly;
390
391static struct inode *bdev_alloc_inode(struct super_block *sb)
392{
393 struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
394
395 if (!ei)
396 return NULL;
397 memset(&ei->bdev, 0, sizeof(ei->bdev));
398 return &ei->vfs_inode;
399}
400
401static void bdev_free_inode(struct inode *inode)
402{
403 struct block_device *bdev = I_BDEV(inode);
404
405 free_percpu(bdev->bd_stats);
406 kfree(bdev->bd_meta_info);
407
408 if (!bdev_is_partition(bdev)) {
409 if (bdev->bd_disk && bdev->bd_disk->bdi)
410 bdi_put(bdev->bd_disk->bdi);
411 kfree(bdev->bd_disk);
412 }
413
414 if (MAJOR(bdev->bd_dev) == BLOCK_EXT_MAJOR)
415 blk_free_ext_minor(MINOR(bdev->bd_dev));
416
417 kmem_cache_free(bdev_cachep, BDEV_I(inode));
418}
419
420static void init_once(void *data)
421{
422 struct bdev_inode *ei = data;
423
424 inode_init_once(&ei->vfs_inode);
425}
426
427static void bdev_evict_inode(struct inode *inode)
428{
429 truncate_inode_pages_final(&inode->i_data);
430 invalidate_inode_buffers(inode); /* is it needed here? */
431 clear_inode(inode);
432}
433
434static const struct super_operations bdev_sops = {
435 .statfs = simple_statfs,
436 .alloc_inode = bdev_alloc_inode,
437 .free_inode = bdev_free_inode,
438 .drop_inode = generic_delete_inode,
439 .evict_inode = bdev_evict_inode,
440};
441
442static int bd_init_fs_context(struct fs_context *fc)
443{
444 struct pseudo_fs_context *ctx = init_pseudo(fc, BDEVFS_MAGIC);
445 if (!ctx)
446 return -ENOMEM;
447 fc->s_iflags |= SB_I_CGROUPWB;
448 ctx->ops = &bdev_sops;
449 return 0;
450}
451
452static struct file_system_type bd_type = {
453 .name = "bdev",
454 .init_fs_context = bd_init_fs_context,
455 .kill_sb = kill_anon_super,
456};
457
458struct super_block *blockdev_superblock __read_mostly;
459EXPORT_SYMBOL_GPL(blockdev_superblock);
460
461void __init bdev_cache_init(void)
462{
463 int err;
464 static struct vfsmount *bd_mnt;
465
466 bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
467 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
468 SLAB_MEM_SPREAD|SLAB_ACCOUNT|SLAB_PANIC),
469 init_once);
470 err = register_filesystem(&bd_type);
471 if (err)
472 panic("Cannot register bdev pseudo-fs");
473 bd_mnt = kern_mount(&bd_type);
474 if (IS_ERR(bd_mnt))
475 panic("Cannot create bdev pseudo-fs");
476 blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */
477}
478
479struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
480{
481 struct block_device *bdev;
482 struct inode *inode;
483
484 inode = new_inode(blockdev_superblock);
485 if (!inode)
486 return NULL;
487 inode->i_mode = S_IFBLK;
488 inode->i_rdev = 0;
489 inode->i_data.a_ops = &def_blk_aops;
490 mapping_set_gfp_mask(&inode->i_data, GFP_USER);
491
492 bdev = I_BDEV(inode);
493 mutex_init(&bdev->bd_fsfreeze_mutex);
494 spin_lock_init(&bdev->bd_size_lock);
495 bdev->bd_partno = partno;
496 bdev->bd_inode = inode;
497 bdev->bd_queue = disk->queue;
498 bdev->bd_stats = alloc_percpu(struct disk_stats);
499 if (!bdev->bd_stats) {
500 iput(inode);
501 return NULL;
502 }
503 bdev->bd_disk = disk;
504 return bdev;
505}
506
507void bdev_add(struct block_device *bdev, dev_t dev)
508{
509 bdev->bd_dev = dev;
510 bdev->bd_inode->i_rdev = dev;
511 bdev->bd_inode->i_ino = dev;
512 insert_inode_hash(bdev->bd_inode);
513}
514
515long nr_blockdev_pages(void)
516{
517 struct inode *inode;
518 long ret = 0;
519
520 spin_lock(&blockdev_superblock->s_inode_list_lock);
521 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list)
522 ret += inode->i_mapping->nrpages;
523 spin_unlock(&blockdev_superblock->s_inode_list_lock);
524
525 return ret;
526}
527
528/**
529 * bd_may_claim - test whether a block device can be claimed
530 * @bdev: block device of interest
531 * @whole: whole block device containing @bdev, may equal @bdev
532 * @holder: holder trying to claim @bdev
533 *
534 * Test whether @bdev can be claimed by @holder.
535 *
536 * CONTEXT:
537 * spin_lock(&bdev_lock).
538 *
539 * RETURNS:
540 * %true if @bdev can be claimed, %false otherwise.
541 */
542static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
543 void *holder)
544{
545 if (bdev->bd_holder == holder)
546 return true; /* already a holder */
547 else if (bdev->bd_holder != NULL)
548 return false; /* held by someone else */
549 else if (whole == bdev)
550 return true; /* is a whole device which isn't held */
551
552 else if (whole->bd_holder == bd_may_claim)
553 return true; /* is a partition of a device that is being partitioned */
554 else if (whole->bd_holder != NULL)
555 return false; /* is a partition of a held device */
556 else
557 return true; /* is a partition of an un-held device */
558}
559
560/**
561 * bd_prepare_to_claim - claim a block device
562 * @bdev: block device of interest
563 * @holder: holder trying to claim @bdev
564 *
565 * Claim @bdev. This function fails if @bdev is already claimed by another
566 * holder and waits if another claiming is in progress. return, the caller
567 * has ownership of bd_claiming and bd_holder[s].
568 *
569 * RETURNS:
570 * 0 if @bdev can be claimed, -EBUSY otherwise.
571 */
572int bd_prepare_to_claim(struct block_device *bdev, void *holder)
573{
574 struct block_device *whole = bdev_whole(bdev);
575
576 if (WARN_ON_ONCE(!holder))
577 return -EINVAL;
578retry:
579 spin_lock(&bdev_lock);
580 /* if someone else claimed, fail */
581 if (!bd_may_claim(bdev, whole, holder)) {
582 spin_unlock(&bdev_lock);
583 return -EBUSY;
584 }
585
586 /* if claiming is already in progress, wait for it to finish */
587 if (whole->bd_claiming) {
588 wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
589 DEFINE_WAIT(wait);
590
591 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
592 spin_unlock(&bdev_lock);
593 schedule();
594 finish_wait(wq, &wait);
595 goto retry;
596 }
597
598 /* yay, all mine */
599 whole->bd_claiming = holder;
600 spin_unlock(&bdev_lock);
601 return 0;
602}
603EXPORT_SYMBOL_GPL(bd_prepare_to_claim); /* only for the loop driver */
604
605static void bd_clear_claiming(struct block_device *whole, void *holder)
606{
607 lockdep_assert_held(&bdev_lock);
608 /* tell others that we're done */
609 BUG_ON(whole->bd_claiming != holder);
610 whole->bd_claiming = NULL;
611 wake_up_bit(&whole->bd_claiming, 0);
612}
613
614/**
615 * bd_finish_claiming - finish claiming of a block device
616 * @bdev: block device of interest
617 * @holder: holder that has claimed @bdev
618 *
619 * Finish exclusive open of a block device. Mark the device as exlusively
620 * open by the holder and wake up all waiters for exclusive open to finish.
621 */
622static void bd_finish_claiming(struct block_device *bdev, void *holder)
623{
624 struct block_device *whole = bdev_whole(bdev);
625
626 spin_lock(&bdev_lock);
627 BUG_ON(!bd_may_claim(bdev, whole, holder));
628 /*
629 * Note that for a whole device bd_holders will be incremented twice,
630 * and bd_holder will be set to bd_may_claim before being set to holder
631 */
632 whole->bd_holders++;
633 whole->bd_holder = bd_may_claim;
634 bdev->bd_holders++;
635 bdev->bd_holder = holder;
636 bd_clear_claiming(whole, holder);
637 spin_unlock(&bdev_lock);
638}
639
640/**
641 * bd_abort_claiming - abort claiming of a block device
642 * @bdev: block device of interest
643 * @holder: holder that has claimed @bdev
644 *
645 * Abort claiming of a block device when the exclusive open failed. This can be
646 * also used when exclusive open is not actually desired and we just needed
647 * to block other exclusive openers for a while.
648 */
649void bd_abort_claiming(struct block_device *bdev, void *holder)
650{
651 spin_lock(&bdev_lock);
652 bd_clear_claiming(bdev_whole(bdev), holder);
653 spin_unlock(&bdev_lock);
654}
655EXPORT_SYMBOL(bd_abort_claiming);
656
657static void blkdev_flush_mapping(struct block_device *bdev)
658{
659 WARN_ON_ONCE(bdev->bd_holders);
660 sync_blockdev(bdev);
661 kill_bdev(bdev);
662 bdev_write_inode(bdev);
663}
664
665static int blkdev_get_whole(struct block_device *bdev, fmode_t mode)
666{
667 struct gendisk *disk = bdev->bd_disk;
668 int ret = 0;
669
670 if (disk->fops->open) {
671 ret = disk->fops->open(bdev, mode);
672 if (ret) {
673 /* avoid ghost partitions on a removed medium */
674 if (ret == -ENOMEDIUM &&
675 test_bit(GD_NEED_PART_SCAN, &disk->state))
676 bdev_disk_changed(disk, true);
677 return ret;
678 }
679 }
680
681 if (!bdev->bd_openers)
682 set_init_blocksize(bdev);
683 if (test_bit(GD_NEED_PART_SCAN, &disk->state))
684 bdev_disk_changed(disk, false);
685 bdev->bd_openers++;
686 return 0;;
687}
688
689static void blkdev_put_whole(struct block_device *bdev, fmode_t mode)
690{
691 if (!--bdev->bd_openers)
692 blkdev_flush_mapping(bdev);
693 if (bdev->bd_disk->fops->release)
694 bdev->bd_disk->fops->release(bdev->bd_disk, mode);
695}
696
697static int blkdev_get_part(struct block_device *part, fmode_t mode)
698{
699 struct gendisk *disk = part->bd_disk;
700 int ret;
701
702 if (part->bd_openers)
703 goto done;
704
705 ret = blkdev_get_whole(bdev_whole(part), mode);
706 if (ret)
707 return ret;
708
709 ret = -ENXIO;
710 if (!bdev_nr_sectors(part))
711 goto out_blkdev_put;
712
713 disk->open_partitions++;
714 set_init_blocksize(part);
715done:
716 part->bd_openers++;
717 return 0;
718
719out_blkdev_put:
720 blkdev_put_whole(bdev_whole(part), mode);
721 return ret;
722}
723
724static void blkdev_put_part(struct block_device *part, fmode_t mode)
725{
726 struct block_device *whole = bdev_whole(part);
727
728 if (--part->bd_openers)
729 return;
730 blkdev_flush_mapping(part);
731 whole->bd_disk->open_partitions--;
732 blkdev_put_whole(whole, mode);
733}
734
735struct block_device *blkdev_get_no_open(dev_t dev)
736{
737 struct block_device *bdev;
738 struct inode *inode;
739
740 inode = ilookup(blockdev_superblock, dev);
741 if (!inode) {
742 blk_request_module(dev);
743 inode = ilookup(blockdev_superblock, dev);
744 if (!inode)
745 return NULL;
746 }
747
748 /* switch from the inode reference to a device mode one: */
749 bdev = &BDEV_I(inode)->bdev;
750 if (!kobject_get_unless_zero(&bdev->bd_device.kobj))
751 bdev = NULL;
752 iput(inode);
753
754 if (!bdev)
755 return NULL;
756 if ((bdev->bd_disk->flags & GENHD_FL_HIDDEN)) {
757 put_device(&bdev->bd_device);
758 return NULL;
759 }
760
761 return bdev;
762}
763
764void blkdev_put_no_open(struct block_device *bdev)
765{
766 put_device(&bdev->bd_device);
767}
768
769/**
770 * blkdev_get_by_dev - open a block device by device number
771 * @dev: device number of block device to open
772 * @mode: FMODE_* mask
773 * @holder: exclusive holder identifier
774 *
775 * Open the block device described by device number @dev. If @mode includes
776 * %FMODE_EXCL, the block device is opened with exclusive access. Specifying
777 * %FMODE_EXCL with a %NULL @holder is invalid. Exclusive opens may nest for
778 * the same @holder.
779 *
780 * Use this interface ONLY if you really do not have anything better - i.e. when
781 * you are behind a truly sucky interface and all you are given is a device
782 * number. Everything else should use blkdev_get_by_path().
783 *
784 * CONTEXT:
785 * Might sleep.
786 *
787 * RETURNS:
788 * Reference to the block_device on success, ERR_PTR(-errno) on failure.
789 */
790struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
791{
792 bool unblock_events = true;
793 struct block_device *bdev;
794 struct gendisk *disk;
795 int ret;
796
797 ret = devcgroup_check_permission(DEVCG_DEV_BLOCK,
798 MAJOR(dev), MINOR(dev),
799 ((mode & FMODE_READ) ? DEVCG_ACC_READ : 0) |
800 ((mode & FMODE_WRITE) ? DEVCG_ACC_WRITE : 0));
801 if (ret)
802 return ERR_PTR(ret);
803
804 bdev = blkdev_get_no_open(dev);
805 if (!bdev)
806 return ERR_PTR(-ENXIO);
807 disk = bdev->bd_disk;
808
809 if (mode & FMODE_EXCL) {
810 ret = bd_prepare_to_claim(bdev, holder);
811 if (ret)
812 goto put_blkdev;
813 }
814
815 disk_block_events(disk);
816
817 mutex_lock(&disk->open_mutex);
818 ret = -ENXIO;
819 if (!disk_live(disk))
820 goto abort_claiming;
821 if (!try_module_get(disk->fops->owner))
822 goto abort_claiming;
823 if (bdev_is_partition(bdev))
824 ret = blkdev_get_part(bdev, mode);
825 else
826 ret = blkdev_get_whole(bdev, mode);
827 if (ret)
828 goto put_module;
829 if (mode & FMODE_EXCL) {
830 bd_finish_claiming(bdev, holder);
831
832 /*
833 * Block event polling for write claims if requested. Any write
834 * holder makes the write_holder state stick until all are
835 * released. This is good enough and tracking individual
836 * writeable reference is too fragile given the way @mode is
837 * used in blkdev_get/put().
838 */
839 if ((mode & FMODE_WRITE) && !bdev->bd_write_holder &&
840 (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
841 bdev->bd_write_holder = true;
842 unblock_events = false;
843 }
844 }
845 mutex_unlock(&disk->open_mutex);
846
847 if (unblock_events)
848 disk_unblock_events(disk);
849 return bdev;
850put_module:
851 module_put(disk->fops->owner);
852abort_claiming:
853 if (mode & FMODE_EXCL)
854 bd_abort_claiming(bdev, holder);
855 mutex_unlock(&disk->open_mutex);
856 disk_unblock_events(disk);
857put_blkdev:
858 blkdev_put_no_open(bdev);
859 return ERR_PTR(ret);
860}
861EXPORT_SYMBOL(blkdev_get_by_dev);
862
863/**
864 * blkdev_get_by_path - open a block device by name
865 * @path: path to the block device to open
866 * @mode: FMODE_* mask
867 * @holder: exclusive holder identifier
868 *
869 * Open the block device described by the device file at @path. If @mode
870 * includes %FMODE_EXCL, the block device is opened with exclusive access.
871 * Specifying %FMODE_EXCL with a %NULL @holder is invalid. Exclusive opens may
872 * nest for the same @holder.
873 *
874 * CONTEXT:
875 * Might sleep.
876 *
877 * RETURNS:
878 * Reference to the block_device on success, ERR_PTR(-errno) on failure.
879 */
880struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
881 void *holder)
882{
883 struct block_device *bdev;
884 dev_t dev;
885 int error;
886
887 error = lookup_bdev(path, &dev);
888 if (error)
889 return ERR_PTR(error);
890
891 bdev = blkdev_get_by_dev(dev, mode, holder);
892 if (!IS_ERR(bdev) && (mode & FMODE_WRITE) && bdev_read_only(bdev)) {
893 blkdev_put(bdev, mode);
894 return ERR_PTR(-EACCES);
895 }
896
897 return bdev;
898}
899EXPORT_SYMBOL(blkdev_get_by_path);
900
901void blkdev_put(struct block_device *bdev, fmode_t mode)
902{
903 struct gendisk *disk = bdev->bd_disk;
904
905 /*
906 * Sync early if it looks like we're the last one. If someone else
907 * opens the block device between now and the decrement of bd_openers
908 * then we did a sync that we didn't need to, but that's not the end
909 * of the world and we want to avoid long (could be several minute)
910 * syncs while holding the mutex.
911 */
912 if (bdev->bd_openers == 1)
913 sync_blockdev(bdev);
914
915 mutex_lock(&disk->open_mutex);
916 if (mode & FMODE_EXCL) {
917 struct block_device *whole = bdev_whole(bdev);
918 bool bdev_free;
919
920 /*
921 * Release a claim on the device. The holder fields
922 * are protected with bdev_lock. open_mutex is to
923 * synchronize disk_holder unlinking.
924 */
925 spin_lock(&bdev_lock);
926
927 WARN_ON_ONCE(--bdev->bd_holders < 0);
928 WARN_ON_ONCE(--whole->bd_holders < 0);
929
930 if ((bdev_free = !bdev->bd_holders))
931 bdev->bd_holder = NULL;
932 if (!whole->bd_holders)
933 whole->bd_holder = NULL;
934
935 spin_unlock(&bdev_lock);
936
937 /*
938 * If this was the last claim, remove holder link and
939 * unblock evpoll if it was a write holder.
940 */
941 if (bdev_free && bdev->bd_write_holder) {
942 disk_unblock_events(disk);
943 bdev->bd_write_holder = false;
944 }
945 }
946
947 /*
948 * Trigger event checking and tell drivers to flush MEDIA_CHANGE
949 * event. This is to ensure detection of media removal commanded
950 * from userland - e.g. eject(1).
951 */
952 disk_flush_events(disk, DISK_EVENT_MEDIA_CHANGE);
953
954 if (bdev_is_partition(bdev))
955 blkdev_put_part(bdev, mode);
956 else
957 blkdev_put_whole(bdev, mode);
958 mutex_unlock(&disk->open_mutex);
959
960 module_put(disk->fops->owner);
961 blkdev_put_no_open(bdev);
962}
963EXPORT_SYMBOL(blkdev_put);
964
965/**
966 * lookup_bdev - lookup a struct block_device by name
967 * @pathname: special file representing the block device
968 * @dev: return value of the block device's dev_t
969 *
970 * Lookup the block device's dev_t at @pathname in the current
971 * namespace if possible and return it by @dev.
972 *
973 * RETURNS:
974 * 0 if succeeded, errno otherwise.
975 */
976int lookup_bdev(const char *pathname, dev_t *dev)
977{
978 struct inode *inode;
979 struct path path;
980 int error;
981
982 if (!pathname || !*pathname)
983 return -EINVAL;
984
985 error = kern_path(pathname, LOOKUP_FOLLOW, &path);
986 if (error)
987 return error;
988
989 inode = d_backing_inode(path.dentry);
990 error = -ENOTBLK;
991 if (!S_ISBLK(inode->i_mode))
992 goto out_path_put;
993 error = -EACCES;
994 if (!may_open_dev(&path))
995 goto out_path_put;
996
997 *dev = inode->i_rdev;
998 error = 0;
999out_path_put:
1000 path_put(&path);
1001 return error;
1002}
1003EXPORT_SYMBOL(lookup_bdev);
1004
1005int __invalidate_device(struct block_device *bdev, bool kill_dirty)
1006{
1007 struct super_block *sb = get_super(bdev);
1008 int res = 0;
1009
1010 if (sb) {
1011 /*
1012 * no need to lock the super, get_super holds the
1013 * read mutex so the filesystem cannot go away
1014 * under us (->put_super runs with the write lock
1015 * hold).
1016 */
1017 shrink_dcache_sb(sb);
1018 res = invalidate_inodes(sb, kill_dirty);
1019 drop_super(sb);
1020 }
1021 invalidate_bdev(bdev);
1022 return res;
1023}
1024EXPORT_SYMBOL(__invalidate_device);
1025
1026void sync_bdevs(bool wait)
1027{
1028 struct inode *inode, *old_inode = NULL;
1029
1030 spin_lock(&blockdev_superblock->s_inode_list_lock);
1031 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
1032 struct address_space *mapping = inode->i_mapping;
1033 struct block_device *bdev;
1034
1035 spin_lock(&inode->i_lock);
1036 if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
1037 mapping->nrpages == 0) {
1038 spin_unlock(&inode->i_lock);
1039 continue;
1040 }
1041 __iget(inode);
1042 spin_unlock(&inode->i_lock);
1043 spin_unlock(&blockdev_superblock->s_inode_list_lock);
1044 /*
1045 * We hold a reference to 'inode' so it couldn't have been
1046 * removed from s_inodes list while we dropped the
1047 * s_inode_list_lock We cannot iput the inode now as we can
1048 * be holding the last reference and we cannot iput it under
1049 * s_inode_list_lock. So we keep the reference and iput it
1050 * later.
1051 */
1052 iput(old_inode);
1053 old_inode = inode;
1054 bdev = I_BDEV(inode);
1055
1056 mutex_lock(&bdev->bd_disk->open_mutex);
1057 if (!bdev->bd_openers) {
1058 ; /* skip */
1059 } else if (wait) {
1060 /*
1061 * We keep the error status of individual mapping so
1062 * that applications can catch the writeback error using
1063 * fsync(2). See filemap_fdatawait_keep_errors() for
1064 * details.
1065 */
1066 filemap_fdatawait_keep_errors(inode->i_mapping);
1067 } else {
1068 filemap_fdatawrite(inode->i_mapping);
1069 }
1070 mutex_unlock(&bdev->bd_disk->open_mutex);
1071
1072 spin_lock(&blockdev_superblock->s_inode_list_lock);
1073 }
1074 spin_unlock(&blockdev_superblock->s_inode_list_lock);
1075 iput(old_inode);
1076}