projects/linux·blob v6.6 · 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/part_stat.h>
28#include <linux/uaccess.h>
29#include <linux/stat.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 pr_warn_ratelimited(
60 "VFS: Dirty inode writeback failed for block device %pg (err=%d).\n",
61 bdev, ret);
62 spin_lock(&inode->i_lock);
63 }
64 spin_unlock(&inode->i_lock);
65}
66
67/* Kill _all_ buffers and pagecache , dirty or not.. */
68static void kill_bdev(struct block_device *bdev)
69{
70 struct address_space *mapping = bdev->bd_inode->i_mapping;
71
72 if (mapping_empty(mapping))
73 return;
74
75 invalidate_bh_lrus();
76 truncate_inode_pages(mapping, 0);
77}
78
79/* Invalidate clean unused buffers and pagecache. */
80void invalidate_bdev(struct block_device *bdev)
81{
82 struct address_space *mapping = bdev->bd_inode->i_mapping;
83
84 if (mapping->nrpages) {
85 invalidate_bh_lrus();
86 lru_add_drain_all(); /* make sure all lru add caches are flushed */
87 invalidate_mapping_pages(mapping, 0, -1);
88 }
89}
90EXPORT_SYMBOL(invalidate_bdev);
91
92/*
93 * Drop all buffers & page cache for given bdev range. This function bails
94 * with error if bdev has other exclusive owner (such as filesystem).
95 */
96int truncate_bdev_range(struct block_device *bdev, blk_mode_t mode,
97 loff_t lstart, loff_t lend)
98{
99 /*
100 * If we don't hold exclusive handle for the device, upgrade to it
101 * while we discard the buffer cache to avoid discarding buffers
102 * under live filesystem.
103 */
104 if (!(mode & BLK_OPEN_EXCL)) {
105 int err = bd_prepare_to_claim(bdev, truncate_bdev_range, NULL);
106 if (err)
107 goto invalidate;
108 }
109
110 truncate_inode_pages_range(bdev->bd_inode->i_mapping, lstart, lend);
111 if (!(mode & BLK_OPEN_EXCL))
112 bd_abort_claiming(bdev, truncate_bdev_range);
113 return 0;
114
115invalidate:
116 /*
117 * Someone else has handle exclusively open. Try invalidating instead.
118 * The 'end' argument is inclusive so the rounding is safe.
119 */
120 return invalidate_inode_pages2_range(bdev->bd_inode->i_mapping,
121 lstart >> PAGE_SHIFT,
122 lend >> PAGE_SHIFT);
123}
124
125static void set_init_blocksize(struct block_device *bdev)
126{
127 unsigned int bsize = bdev_logical_block_size(bdev);
128 loff_t size = i_size_read(bdev->bd_inode);
129
130 while (bsize < PAGE_SIZE) {
131 if (size & bsize)
132 break;
133 bsize <<= 1;
134 }
135 bdev->bd_inode->i_blkbits = blksize_bits(bsize);
136}
137
138int set_blocksize(struct block_device *bdev, int size)
139{
140 /* Size must be a power of two, and between 512 and PAGE_SIZE */
141 if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
142 return -EINVAL;
143
144 /* Size cannot be smaller than the size supported by the device */
145 if (size < bdev_logical_block_size(bdev))
146 return -EINVAL;
147
148 /* Don't change the size if it is same as current */
149 if (bdev->bd_inode->i_blkbits != blksize_bits(size)) {
150 sync_blockdev(bdev);
151 bdev->bd_inode->i_blkbits = blksize_bits(size);
152 kill_bdev(bdev);
153 }
154 return 0;
155}
156
157EXPORT_SYMBOL(set_blocksize);
158
159int sb_set_blocksize(struct super_block *sb, int size)
160{
161 if (set_blocksize(sb->s_bdev, size))
162 return 0;
163 /* If we get here, we know size is power of two
164 * and it's value is between 512 and PAGE_SIZE */
165 sb->s_blocksize = size;
166 sb->s_blocksize_bits = blksize_bits(size);
167 return sb->s_blocksize;
168}
169
170EXPORT_SYMBOL(sb_set_blocksize);
171
172int sb_min_blocksize(struct super_block *sb, int size)
173{
174 int minsize = bdev_logical_block_size(sb->s_bdev);
175 if (size < minsize)
176 size = minsize;
177 return sb_set_blocksize(sb, size);
178}
179
180EXPORT_SYMBOL(sb_min_blocksize);
181
182int sync_blockdev_nowait(struct block_device *bdev)
183{
184 if (!bdev)
185 return 0;
186 return filemap_flush(bdev->bd_inode->i_mapping);
187}
188EXPORT_SYMBOL_GPL(sync_blockdev_nowait);
189
190/*
191 * Write out and wait upon all the dirty data associated with a block
192 * device via its mapping. Does not take the superblock lock.
193 */
194int sync_blockdev(struct block_device *bdev)
195{
196 if (!bdev)
197 return 0;
198 return filemap_write_and_wait(bdev->bd_inode->i_mapping);
199}
200EXPORT_SYMBOL(sync_blockdev);
201
202int sync_blockdev_range(struct block_device *bdev, loff_t lstart, loff_t lend)
203{
204 return filemap_write_and_wait_range(bdev->bd_inode->i_mapping,
205 lstart, lend);
206}
207EXPORT_SYMBOL(sync_blockdev_range);
208
209/**
210 * freeze_bdev - lock a filesystem and force it into a consistent state
211 * @bdev: blockdevice to lock
212 *
213 * If a superblock is found on this device, we take the s_umount semaphore
214 * on it to make sure nobody unmounts until the snapshot creation is done.
215 * The reference counter (bd_fsfreeze_count) guarantees that only the last
216 * unfreeze process can unfreeze the frozen filesystem actually when multiple
217 * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
218 * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
219 * actually.
220 */
221int freeze_bdev(struct block_device *bdev)
222{
223 struct super_block *sb;
224 int error = 0;
225
226 mutex_lock(&bdev->bd_fsfreeze_mutex);
227 if (++bdev->bd_fsfreeze_count > 1)
228 goto done;
229
230 sb = get_active_super(bdev);
231 if (!sb)
232 goto sync;
233 if (sb->s_op->freeze_super)
234 error = sb->s_op->freeze_super(sb, FREEZE_HOLDER_USERSPACE);
235 else
236 error = freeze_super(sb, FREEZE_HOLDER_USERSPACE);
237 deactivate_super(sb);
238
239 if (error) {
240 bdev->bd_fsfreeze_count--;
241 goto done;
242 }
243 bdev->bd_fsfreeze_sb = sb;
244
245sync:
246 sync_blockdev(bdev);
247done:
248 mutex_unlock(&bdev->bd_fsfreeze_mutex);
249 return error;
250}
251EXPORT_SYMBOL(freeze_bdev);
252
253/**
254 * thaw_bdev - unlock filesystem
255 * @bdev: blockdevice to unlock
256 *
257 * Unlocks the filesystem and marks it writeable again after freeze_bdev().
258 */
259int thaw_bdev(struct block_device *bdev)
260{
261 struct super_block *sb;
262 int error = -EINVAL;
263
264 mutex_lock(&bdev->bd_fsfreeze_mutex);
265 if (!bdev->bd_fsfreeze_count)
266 goto out;
267
268 error = 0;
269 if (--bdev->bd_fsfreeze_count > 0)
270 goto out;
271
272 sb = bdev->bd_fsfreeze_sb;
273 if (!sb)
274 goto out;
275
276 if (sb->s_op->thaw_super)
277 error = sb->s_op->thaw_super(sb, FREEZE_HOLDER_USERSPACE);
278 else
279 error = thaw_super(sb, FREEZE_HOLDER_USERSPACE);
280 if (error)
281 bdev->bd_fsfreeze_count++;
282 else
283 bdev->bd_fsfreeze_sb = NULL;
284out:
285 mutex_unlock(&bdev->bd_fsfreeze_mutex);
286 return error;
287}
288EXPORT_SYMBOL(thaw_bdev);
289
290/*
291 * pseudo-fs
292 */
293
294static __cacheline_aligned_in_smp DEFINE_MUTEX(bdev_lock);
295static struct kmem_cache * bdev_cachep __read_mostly;
296
297static struct inode *bdev_alloc_inode(struct super_block *sb)
298{
299 struct bdev_inode *ei = alloc_inode_sb(sb, bdev_cachep, GFP_KERNEL);
300
301 if (!ei)
302 return NULL;
303 memset(&ei->bdev, 0, sizeof(ei->bdev));
304 return &ei->vfs_inode;
305}
306
307static void bdev_free_inode(struct inode *inode)
308{
309 struct block_device *bdev = I_BDEV(inode);
310
311 free_percpu(bdev->bd_stats);
312 kfree(bdev->bd_meta_info);
313
314 if (!bdev_is_partition(bdev)) {
315 if (bdev->bd_disk && bdev->bd_disk->bdi)
316 bdi_put(bdev->bd_disk->bdi);
317 kfree(bdev->bd_disk);
318 }
319
320 if (MAJOR(bdev->bd_dev) == BLOCK_EXT_MAJOR)
321 blk_free_ext_minor(MINOR(bdev->bd_dev));
322
323 kmem_cache_free(bdev_cachep, BDEV_I(inode));
324}
325
326static void init_once(void *data)
327{
328 struct bdev_inode *ei = data;
329
330 inode_init_once(&ei->vfs_inode);
331}
332
333static void bdev_evict_inode(struct inode *inode)
334{
335 truncate_inode_pages_final(&inode->i_data);
336 invalidate_inode_buffers(inode); /* is it needed here? */
337 clear_inode(inode);
338}
339
340static const struct super_operations bdev_sops = {
341 .statfs = simple_statfs,
342 .alloc_inode = bdev_alloc_inode,
343 .free_inode = bdev_free_inode,
344 .drop_inode = generic_delete_inode,
345 .evict_inode = bdev_evict_inode,
346};
347
348static int bd_init_fs_context(struct fs_context *fc)
349{
350 struct pseudo_fs_context *ctx = init_pseudo(fc, BDEVFS_MAGIC);
351 if (!ctx)
352 return -ENOMEM;
353 fc->s_iflags |= SB_I_CGROUPWB;
354 ctx->ops = &bdev_sops;
355 return 0;
356}
357
358static struct file_system_type bd_type = {
359 .name = "bdev",
360 .init_fs_context = bd_init_fs_context,
361 .kill_sb = kill_anon_super,
362};
363
364struct super_block *blockdev_superblock __read_mostly;
365EXPORT_SYMBOL_GPL(blockdev_superblock);
366
367void __init bdev_cache_init(void)
368{
369 int err;
370 static struct vfsmount *bd_mnt;
371
372 bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
373 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
374 SLAB_MEM_SPREAD|SLAB_ACCOUNT|SLAB_PANIC),
375 init_once);
376 err = register_filesystem(&bd_type);
377 if (err)
378 panic("Cannot register bdev pseudo-fs");
379 bd_mnt = kern_mount(&bd_type);
380 if (IS_ERR(bd_mnt))
381 panic("Cannot create bdev pseudo-fs");
382 blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */
383}
384
385struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
386{
387 struct block_device *bdev;
388 struct inode *inode;
389
390 inode = new_inode(blockdev_superblock);
391 if (!inode)
392 return NULL;
393 inode->i_mode = S_IFBLK;
394 inode->i_rdev = 0;
395 inode->i_data.a_ops = &def_blk_aops;
396 mapping_set_gfp_mask(&inode->i_data, GFP_USER);
397
398 bdev = I_BDEV(inode);
399 mutex_init(&bdev->bd_fsfreeze_mutex);
400 spin_lock_init(&bdev->bd_size_lock);
401 mutex_init(&bdev->bd_holder_lock);
402 bdev->bd_partno = partno;
403 bdev->bd_inode = inode;
404 bdev->bd_queue = disk->queue;
405 if (partno)
406 bdev->bd_has_submit_bio = disk->part0->bd_has_submit_bio;
407 else
408 bdev->bd_has_submit_bio = false;
409 bdev->bd_stats = alloc_percpu(struct disk_stats);
410 if (!bdev->bd_stats) {
411 iput(inode);
412 return NULL;
413 }
414 bdev->bd_disk = disk;
415 return bdev;
416}
417
418void bdev_set_nr_sectors(struct block_device *bdev, sector_t sectors)
419{
420 spin_lock(&bdev->bd_size_lock);
421 i_size_write(bdev->bd_inode, (loff_t)sectors << SECTOR_SHIFT);
422 bdev->bd_nr_sectors = sectors;
423 spin_unlock(&bdev->bd_size_lock);
424}
425
426void bdev_add(struct block_device *bdev, dev_t dev)
427{
428 bdev->bd_dev = dev;
429 bdev->bd_inode->i_rdev = dev;
430 bdev->bd_inode->i_ino = dev;
431 insert_inode_hash(bdev->bd_inode);
432}
433
434long nr_blockdev_pages(void)
435{
436 struct inode *inode;
437 long ret = 0;
438
439 spin_lock(&blockdev_superblock->s_inode_list_lock);
440 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list)
441 ret += inode->i_mapping->nrpages;
442 spin_unlock(&blockdev_superblock->s_inode_list_lock);
443
444 return ret;
445}
446
447/**
448 * bd_may_claim - test whether a block device can be claimed
449 * @bdev: block device of interest
450 * @holder: holder trying to claim @bdev
451 * @hops: holder ops
452 *
453 * Test whether @bdev can be claimed by @holder.
454 *
455 * RETURNS:
456 * %true if @bdev can be claimed, %false otherwise.
457 */
458static bool bd_may_claim(struct block_device *bdev, void *holder,
459 const struct blk_holder_ops *hops)
460{
461 struct block_device *whole = bdev_whole(bdev);
462
463 lockdep_assert_held(&bdev_lock);
464
465 if (bdev->bd_holder) {
466 /*
467 * The same holder can always re-claim.
468 */
469 if (bdev->bd_holder == holder) {
470 if (WARN_ON_ONCE(bdev->bd_holder_ops != hops))
471 return false;
472 return true;
473 }
474 return false;
475 }
476
477 /*
478 * If the whole devices holder is set to bd_may_claim, a partition on
479 * the device is claimed, but not the whole device.
480 */
481 if (whole != bdev &&
482 whole->bd_holder && whole->bd_holder != bd_may_claim)
483 return false;
484 return true;
485}
486
487/**
488 * bd_prepare_to_claim - claim a block device
489 * @bdev: block device of interest
490 * @holder: holder trying to claim @bdev
491 * @hops: holder ops.
492 *
493 * Claim @bdev. This function fails if @bdev is already claimed by another
494 * holder and waits if another claiming is in progress. return, the caller
495 * has ownership of bd_claiming and bd_holder[s].
496 *
497 * RETURNS:
498 * 0 if @bdev can be claimed, -EBUSY otherwise.
499 */
500int bd_prepare_to_claim(struct block_device *bdev, void *holder,
501 const struct blk_holder_ops *hops)
502{
503 struct block_device *whole = bdev_whole(bdev);
504
505 if (WARN_ON_ONCE(!holder))
506 return -EINVAL;
507retry:
508 mutex_lock(&bdev_lock);
509 /* if someone else claimed, fail */
510 if (!bd_may_claim(bdev, holder, hops)) {
511 mutex_unlock(&bdev_lock);
512 return -EBUSY;
513 }
514
515 /* if claiming is already in progress, wait for it to finish */
516 if (whole->bd_claiming) {
517 wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
518 DEFINE_WAIT(wait);
519
520 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
521 mutex_unlock(&bdev_lock);
522 schedule();
523 finish_wait(wq, &wait);
524 goto retry;
525 }
526
527 /* yay, all mine */
528 whole->bd_claiming = holder;
529 mutex_unlock(&bdev_lock);
530 return 0;
531}
532EXPORT_SYMBOL_GPL(bd_prepare_to_claim); /* only for the loop driver */
533
534static void bd_clear_claiming(struct block_device *whole, void *holder)
535{
536 lockdep_assert_held(&bdev_lock);
537 /* tell others that we're done */
538 BUG_ON(whole->bd_claiming != holder);
539 whole->bd_claiming = NULL;
540 wake_up_bit(&whole->bd_claiming, 0);
541}
542
543/**
544 * bd_finish_claiming - finish claiming of a block device
545 * @bdev: block device of interest
546 * @holder: holder that has claimed @bdev
547 * @hops: block device holder operations
548 *
549 * Finish exclusive open of a block device. Mark the device as exlusively
550 * open by the holder and wake up all waiters for exclusive open to finish.
551 */
552static void bd_finish_claiming(struct block_device *bdev, void *holder,
553 const struct blk_holder_ops *hops)
554{
555 struct block_device *whole = bdev_whole(bdev);
556
557 mutex_lock(&bdev_lock);
558 BUG_ON(!bd_may_claim(bdev, holder, hops));
559 /*
560 * Note that for a whole device bd_holders will be incremented twice,
561 * and bd_holder will be set to bd_may_claim before being set to holder
562 */
563 whole->bd_holders++;
564 whole->bd_holder = bd_may_claim;
565 bdev->bd_holders++;
566 mutex_lock(&bdev->bd_holder_lock);
567 bdev->bd_holder = holder;
568 bdev->bd_holder_ops = hops;
569 mutex_unlock(&bdev->bd_holder_lock);
570 bd_clear_claiming(whole, holder);
571 mutex_unlock(&bdev_lock);
572}
573
574/**
575 * bd_abort_claiming - abort claiming of a block device
576 * @bdev: block device of interest
577 * @holder: holder that has claimed @bdev
578 *
579 * Abort claiming of a block device when the exclusive open failed. This can be
580 * also used when exclusive open is not actually desired and we just needed
581 * to block other exclusive openers for a while.
582 */
583void bd_abort_claiming(struct block_device *bdev, void *holder)
584{
585 mutex_lock(&bdev_lock);
586 bd_clear_claiming(bdev_whole(bdev), holder);
587 mutex_unlock(&bdev_lock);
588}
589EXPORT_SYMBOL(bd_abort_claiming);
590
591static void bd_end_claim(struct block_device *bdev, void *holder)
592{
593 struct block_device *whole = bdev_whole(bdev);
594 bool unblock = false;
595
596 /*
597 * Release a claim on the device. The holder fields are protected with
598 * bdev_lock. open_mutex is used to synchronize disk_holder unlinking.
599 */
600 mutex_lock(&bdev_lock);
601 WARN_ON_ONCE(bdev->bd_holder != holder);
602 WARN_ON_ONCE(--bdev->bd_holders < 0);
603 WARN_ON_ONCE(--whole->bd_holders < 0);
604 if (!bdev->bd_holders) {
605 mutex_lock(&bdev->bd_holder_lock);
606 bdev->bd_holder = NULL;
607 bdev->bd_holder_ops = NULL;
608 mutex_unlock(&bdev->bd_holder_lock);
609 if (bdev->bd_write_holder)
610 unblock = true;
611 }
612 if (!whole->bd_holders)
613 whole->bd_holder = NULL;
614 mutex_unlock(&bdev_lock);
615
616 /*
617 * If this was the last claim, remove holder link and unblock evpoll if
618 * it was a write holder.
619 */
620 if (unblock) {
621 disk_unblock_events(bdev->bd_disk);
622 bdev->bd_write_holder = false;
623 }
624}
625
626static void blkdev_flush_mapping(struct block_device *bdev)
627{
628 WARN_ON_ONCE(bdev->bd_holders);
629 sync_blockdev(bdev);
630 kill_bdev(bdev);
631 bdev_write_inode(bdev);
632}
633
634static int blkdev_get_whole(struct block_device *bdev, blk_mode_t mode)
635{
636 struct gendisk *disk = bdev->bd_disk;
637 int ret;
638
639 if (disk->fops->open) {
640 ret = disk->fops->open(disk, mode);
641 if (ret) {
642 /* avoid ghost partitions on a removed medium */
643 if (ret == -ENOMEDIUM &&
644 test_bit(GD_NEED_PART_SCAN, &disk->state))
645 bdev_disk_changed(disk, true);
646 return ret;
647 }
648 }
649
650 if (!atomic_read(&bdev->bd_openers))
651 set_init_blocksize(bdev);
652 if (test_bit(GD_NEED_PART_SCAN, &disk->state))
653 bdev_disk_changed(disk, false);
654 atomic_inc(&bdev->bd_openers);
655 return 0;
656}
657
658static void blkdev_put_whole(struct block_device *bdev)
659{
660 if (atomic_dec_and_test(&bdev->bd_openers))
661 blkdev_flush_mapping(bdev);
662 if (bdev->bd_disk->fops->release)
663 bdev->bd_disk->fops->release(bdev->bd_disk);
664}
665
666static int blkdev_get_part(struct block_device *part, blk_mode_t mode)
667{
668 struct gendisk *disk = part->bd_disk;
669 int ret;
670
671 ret = blkdev_get_whole(bdev_whole(part), mode);
672 if (ret)
673 return ret;
674
675 ret = -ENXIO;
676 if (!bdev_nr_sectors(part))
677 goto out_blkdev_put;
678
679 if (!atomic_read(&part->bd_openers)) {
680 disk->open_partitions++;
681 set_init_blocksize(part);
682 }
683 atomic_inc(&part->bd_openers);
684 return 0;
685
686out_blkdev_put:
687 blkdev_put_whole(bdev_whole(part));
688 return ret;
689}
690
691static void blkdev_put_part(struct block_device *part)
692{
693 struct block_device *whole = bdev_whole(part);
694
695 if (atomic_dec_and_test(&part->bd_openers)) {
696 blkdev_flush_mapping(part);
697 whole->bd_disk->open_partitions--;
698 }
699 blkdev_put_whole(whole);
700}
701
702struct block_device *blkdev_get_no_open(dev_t dev)
703{
704 struct block_device *bdev;
705 struct inode *inode;
706
707 inode = ilookup(blockdev_superblock, dev);
708 if (!inode && IS_ENABLED(CONFIG_BLOCK_LEGACY_AUTOLOAD)) {
709 blk_request_module(dev);
710 inode = ilookup(blockdev_superblock, dev);
711 if (inode)
712 pr_warn_ratelimited(
713"block device autoloading is deprecated and will be removed.\n");
714 }
715 if (!inode)
716 return NULL;
717
718 /* switch from the inode reference to a device mode one: */
719 bdev = &BDEV_I(inode)->bdev;
720 if (!kobject_get_unless_zero(&bdev->bd_device.kobj))
721 bdev = NULL;
722 iput(inode);
723 return bdev;
724}
725
726void blkdev_put_no_open(struct block_device *bdev)
727{
728 put_device(&bdev->bd_device);
729}
730
731/**
732 * blkdev_get_by_dev - open a block device by device number
733 * @dev: device number of block device to open
734 * @mode: open mode (BLK_OPEN_*)
735 * @holder: exclusive holder identifier
736 * @hops: holder operations
737 *
738 * Open the block device described by device number @dev. If @holder is not
739 * %NULL, the block device is opened with exclusive access. Exclusive opens may
740 * nest for the same @holder.
741 *
742 * Use this interface ONLY if you really do not have anything better - i.e. when
743 * you are behind a truly sucky interface and all you are given is a device
744 * number. Everything else should use blkdev_get_by_path().
745 *
746 * CONTEXT:
747 * Might sleep.
748 *
749 * RETURNS:
750 * Reference to the block_device on success, ERR_PTR(-errno) on failure.
751 */
752struct block_device *blkdev_get_by_dev(dev_t dev, blk_mode_t mode, void *holder,
753 const struct blk_holder_ops *hops)
754{
755 bool unblock_events = true;
756 struct block_device *bdev;
757 struct gendisk *disk;
758 int ret;
759
760 ret = devcgroup_check_permission(DEVCG_DEV_BLOCK,
761 MAJOR(dev), MINOR(dev),
762 ((mode & BLK_OPEN_READ) ? DEVCG_ACC_READ : 0) |
763 ((mode & BLK_OPEN_WRITE) ? DEVCG_ACC_WRITE : 0));
764 if (ret)
765 return ERR_PTR(ret);
766
767 bdev = blkdev_get_no_open(dev);
768 if (!bdev)
769 return ERR_PTR(-ENXIO);
770 disk = bdev->bd_disk;
771
772 if (holder) {
773 mode |= BLK_OPEN_EXCL;
774 ret = bd_prepare_to_claim(bdev, holder, hops);
775 if (ret)
776 goto put_blkdev;
777 } else {
778 if (WARN_ON_ONCE(mode & BLK_OPEN_EXCL)) {
779 ret = -EIO;
780 goto put_blkdev;
781 }
782 }
783
784 disk_block_events(disk);
785
786 mutex_lock(&disk->open_mutex);
787 ret = -ENXIO;
788 if (!disk_live(disk))
789 goto abort_claiming;
790 if (!try_module_get(disk->fops->owner))
791 goto abort_claiming;
792 if (bdev_is_partition(bdev))
793 ret = blkdev_get_part(bdev, mode);
794 else
795 ret = blkdev_get_whole(bdev, mode);
796 if (ret)
797 goto put_module;
798 if (holder) {
799 bd_finish_claiming(bdev, holder, hops);
800
801 /*
802 * Block event polling for write claims if requested. Any write
803 * holder makes the write_holder state stick until all are
804 * released. This is good enough and tracking individual
805 * writeable reference is too fragile given the way @mode is
806 * used in blkdev_get/put().
807 */
808 if ((mode & BLK_OPEN_WRITE) && !bdev->bd_write_holder &&
809 (disk->event_flags & DISK_EVENT_FLAG_BLOCK_ON_EXCL_WRITE)) {
810 bdev->bd_write_holder = true;
811 unblock_events = false;
812 }
813 }
814 mutex_unlock(&disk->open_mutex);
815
816 if (unblock_events)
817 disk_unblock_events(disk);
818 return bdev;
819put_module:
820 module_put(disk->fops->owner);
821abort_claiming:
822 if (holder)
823 bd_abort_claiming(bdev, holder);
824 mutex_unlock(&disk->open_mutex);
825 disk_unblock_events(disk);
826put_blkdev:
827 blkdev_put_no_open(bdev);
828 return ERR_PTR(ret);
829}
830EXPORT_SYMBOL(blkdev_get_by_dev);
831
832/**
833 * blkdev_get_by_path - open a block device by name
834 * @path: path to the block device to open
835 * @mode: open mode (BLK_OPEN_*)
836 * @holder: exclusive holder identifier
837 * @hops: holder operations
838 *
839 * Open the block device described by the device file at @path. If @holder is
840 * not %NULL, the block device is opened with exclusive access. Exclusive opens
841 * may nest for the same @holder.
842 *
843 * CONTEXT:
844 * Might sleep.
845 *
846 * RETURNS:
847 * Reference to the block_device on success, ERR_PTR(-errno) on failure.
848 */
849struct block_device *blkdev_get_by_path(const char *path, blk_mode_t mode,
850 void *holder, const struct blk_holder_ops *hops)
851{
852 struct block_device *bdev;
853 dev_t dev;
854 int error;
855
856 error = lookup_bdev(path, &dev);
857 if (error)
858 return ERR_PTR(error);
859
860 bdev = blkdev_get_by_dev(dev, mode, holder, hops);
861 if (!IS_ERR(bdev) && (mode & BLK_OPEN_WRITE) && bdev_read_only(bdev)) {
862 blkdev_put(bdev, holder);
863 return ERR_PTR(-EACCES);
864 }
865
866 return bdev;
867}
868EXPORT_SYMBOL(blkdev_get_by_path);
869
870void blkdev_put(struct block_device *bdev, void *holder)
871{
872 struct gendisk *disk = bdev->bd_disk;
873
874 /*
875 * Sync early if it looks like we're the last one. If someone else
876 * opens the block device between now and the decrement of bd_openers
877 * then we did a sync that we didn't need to, but that's not the end
878 * of the world and we want to avoid long (could be several minute)
879 * syncs while holding the mutex.
880 */
881 if (atomic_read(&bdev->bd_openers) == 1)
882 sync_blockdev(bdev);
883
884 mutex_lock(&disk->open_mutex);
885 if (holder)
886 bd_end_claim(bdev, holder);
887
888 /*
889 * Trigger event checking and tell drivers to flush MEDIA_CHANGE
890 * event. This is to ensure detection of media removal commanded
891 * from userland - e.g. eject(1).
892 */
893 disk_flush_events(disk, DISK_EVENT_MEDIA_CHANGE);
894
895 if (bdev_is_partition(bdev))
896 blkdev_put_part(bdev);
897 else
898 blkdev_put_whole(bdev);
899 mutex_unlock(&disk->open_mutex);
900
901 module_put(disk->fops->owner);
902 blkdev_put_no_open(bdev);
903}
904EXPORT_SYMBOL(blkdev_put);
905
906/**
907 * lookup_bdev() - Look up a struct block_device by name.
908 * @pathname: Name of the block device in the filesystem.
909 * @dev: Pointer to the block device's dev_t, if found.
910 *
911 * Lookup the block device's dev_t at @pathname in the current
912 * namespace if possible and return it in @dev.
913 *
914 * Context: May sleep.
915 * Return: 0 if succeeded, negative errno otherwise.
916 */
917int lookup_bdev(const char *pathname, dev_t *dev)
918{
919 struct inode *inode;
920 struct path path;
921 int error;
922
923 if (!pathname || !*pathname)
924 return -EINVAL;
925
926 error = kern_path(pathname, LOOKUP_FOLLOW, &path);
927 if (error)
928 return error;
929
930 inode = d_backing_inode(path.dentry);
931 error = -ENOTBLK;
932 if (!S_ISBLK(inode->i_mode))
933 goto out_path_put;
934 error = -EACCES;
935 if (!may_open_dev(&path))
936 goto out_path_put;
937
938 *dev = inode->i_rdev;
939 error = 0;
940out_path_put:
941 path_put(&path);
942 return error;
943}
944EXPORT_SYMBOL(lookup_bdev);
945
946/**
947 * bdev_mark_dead - mark a block device as dead
948 * @bdev: block device to operate on
949 * @surprise: indicate a surprise removal
950 *
951 * Tell the file system that this devices or media is dead. If @surprise is set
952 * to %true the device or media is already gone, if not we are preparing for an
953 * orderly removal.
954 *
955 * This calls into the file system, which then typicall syncs out all dirty data
956 * and writes back inodes and then invalidates any cached data in the inodes on
957 * the file system. In addition we also invalidate the block device mapping.
958 */
959void bdev_mark_dead(struct block_device *bdev, bool surprise)
960{
961 mutex_lock(&bdev->bd_holder_lock);
962 if (bdev->bd_holder_ops && bdev->bd_holder_ops->mark_dead)
963 bdev->bd_holder_ops->mark_dead(bdev, surprise);
964 else
965 sync_blockdev(bdev);
966 mutex_unlock(&bdev->bd_holder_lock);
967
968 invalidate_bdev(bdev);
969}
970#ifdef CONFIG_DASD_MODULE
971/*
972 * Drivers should not use this directly, but the DASD driver has historically
973 * had a shutdown to offline mode that doesn't actually remove the gendisk
974 * that otherwise looks a lot like a safe device removal.
975 */
976EXPORT_SYMBOL_GPL(bdev_mark_dead);
977#endif
978
979void sync_bdevs(bool wait)
980{
981 struct inode *inode, *old_inode = NULL;
982
983 spin_lock(&blockdev_superblock->s_inode_list_lock);
984 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
985 struct address_space *mapping = inode->i_mapping;
986 struct block_device *bdev;
987
988 spin_lock(&inode->i_lock);
989 if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
990 mapping->nrpages == 0) {
991 spin_unlock(&inode->i_lock);
992 continue;
993 }
994 __iget(inode);
995 spin_unlock(&inode->i_lock);
996 spin_unlock(&blockdev_superblock->s_inode_list_lock);
997 /*
998 * We hold a reference to 'inode' so it couldn't have been
999 * removed from s_inodes list while we dropped the
1000 * s_inode_list_lock We cannot iput the inode now as we can
1001 * be holding the last reference and we cannot iput it under
1002 * s_inode_list_lock. So we keep the reference and iput it
1003 * later.
1004 */
1005 iput(old_inode);
1006 old_inode = inode;
1007 bdev = I_BDEV(inode);
1008
1009 mutex_lock(&bdev->bd_disk->open_mutex);
1010 if (!atomic_read(&bdev->bd_openers)) {
1011 ; /* skip */
1012 } else if (wait) {
1013 /*
1014 * We keep the error status of individual mapping so
1015 * that applications can catch the writeback error using
1016 * fsync(2). See filemap_fdatawait_keep_errors() for
1017 * details.
1018 */
1019 filemap_fdatawait_keep_errors(inode->i_mapping);
1020 } else {
1021 filemap_fdatawrite(inode->i_mapping);
1022 }
1023 mutex_unlock(&bdev->bd_disk->open_mutex);
1024
1025 spin_lock(&blockdev_superblock->s_inode_list_lock);
1026 }
1027 spin_unlock(&blockdev_superblock->s_inode_list_lock);
1028 iput(old_inode);
1029}
1030
1031/*
1032 * Handle STATX_DIOALIGN for block devices.
1033 *
1034 * Note that the inode passed to this is the inode of a block device node file,
1035 * not the block device's internal inode. Therefore it is *not* valid to use
1036 * I_BDEV() here; the block device has to be looked up by i_rdev instead.
1037 */
1038void bdev_statx_dioalign(struct inode *inode, struct kstat *stat)
1039{
1040 struct block_device *bdev;
1041
1042 bdev = blkdev_get_no_open(inode->i_rdev);
1043 if (!bdev)
1044 return;
1045
1046 stat->dio_mem_align = bdev_dma_alignment(bdev) + 1;
1047 stat->dio_offset_align = bdev_logical_block_size(bdev);
1048 stat->result_mask |= STATX_DIOALIGN;
1049
1050 blkdev_put_no_open(bdev);
1051}