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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/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/security.h>
28#include <linux/part_stat.h>
29#include <linux/uaccess.h>
30#include <linux/stat.h>
31#include "../fs/internal.h"
32#include "blk.h"
33
34/* Should we allow writing to mounted block devices? */
35static bool bdev_allow_write_mounted = IS_ENABLED(CONFIG_BLK_DEV_WRITE_MOUNTED);
36
37struct bdev_inode {
38 struct block_device bdev;
39 struct inode vfs_inode;
40};
41
42static inline struct bdev_inode *BDEV_I(struct inode *inode)
43{
44 return container_of(inode, struct bdev_inode, vfs_inode);
45}
46
47static inline struct inode *BD_INODE(struct block_device *bdev)
48{
49 return &container_of(bdev, struct bdev_inode, bdev)->vfs_inode;
50}
51
52struct block_device *I_BDEV(struct inode *inode)
53{
54 return &BDEV_I(inode)->bdev;
55}
56EXPORT_SYMBOL(I_BDEV);
57
58struct block_device *file_bdev(struct file *bdev_file)
59{
60 return I_BDEV(bdev_file->f_mapping->host);
61}
62EXPORT_SYMBOL(file_bdev);
63
64static void bdev_write_inode(struct block_device *bdev)
65{
66 struct inode *inode = BD_INODE(bdev);
67 int ret;
68
69 spin_lock(&inode->i_lock);
70 while (inode->i_state & I_DIRTY) {
71 spin_unlock(&inode->i_lock);
72 ret = write_inode_now(inode, true);
73 if (ret)
74 pr_warn_ratelimited(
75 "VFS: Dirty inode writeback failed for block device %pg (err=%d).\n",
76 bdev, ret);
77 spin_lock(&inode->i_lock);
78 }
79 spin_unlock(&inode->i_lock);
80}
81
82/* Kill _all_ buffers and pagecache , dirty or not.. */
83static void kill_bdev(struct block_device *bdev)
84{
85 struct address_space *mapping = bdev->bd_mapping;
86
87 if (mapping_empty(mapping))
88 return;
89
90 invalidate_bh_lrus();
91 truncate_inode_pages(mapping, 0);
92}
93
94/* Invalidate clean unused buffers and pagecache. */
95void invalidate_bdev(struct block_device *bdev)
96{
97 struct address_space *mapping = bdev->bd_mapping;
98
99 if (mapping->nrpages) {
100 invalidate_bh_lrus();
101 lru_add_drain_all(); /* make sure all lru add caches are flushed */
102 invalidate_mapping_pages(mapping, 0, -1);
103 }
104}
105EXPORT_SYMBOL(invalidate_bdev);
106
107/*
108 * Drop all buffers & page cache for given bdev range. This function bails
109 * with error if bdev has other exclusive owner (such as filesystem).
110 */
111int truncate_bdev_range(struct block_device *bdev, blk_mode_t mode,
112 loff_t lstart, loff_t lend)
113{
114 /*
115 * If we don't hold exclusive handle for the device, upgrade to it
116 * while we discard the buffer cache to avoid discarding buffers
117 * under live filesystem.
118 */
119 if (!(mode & BLK_OPEN_EXCL)) {
120 int err = bd_prepare_to_claim(bdev, truncate_bdev_range, NULL);
121 if (err)
122 goto invalidate;
123 }
124
125 truncate_inode_pages_range(bdev->bd_mapping, lstart, lend);
126 if (!(mode & BLK_OPEN_EXCL))
127 bd_abort_claiming(bdev, truncate_bdev_range);
128 return 0;
129
130invalidate:
131 /*
132 * Someone else has handle exclusively open. Try invalidating instead.
133 * The 'end' argument is inclusive so the rounding is safe.
134 */
135 return invalidate_inode_pages2_range(bdev->bd_mapping,
136 lstart >> PAGE_SHIFT,
137 lend >> PAGE_SHIFT);
138}
139
140static void set_init_blocksize(struct block_device *bdev)
141{
142 unsigned int bsize = bdev_logical_block_size(bdev);
143 loff_t size = i_size_read(BD_INODE(bdev));
144
145 while (bsize < PAGE_SIZE) {
146 if (size & bsize)
147 break;
148 bsize <<= 1;
149 }
150 BD_INODE(bdev)->i_blkbits = blksize_bits(bsize);
151}
152
153int set_blocksize(struct file *file, int size)
154{
155 struct inode *inode = file->f_mapping->host;
156 struct block_device *bdev = I_BDEV(inode);
157
158 if (blk_validate_block_size(size))
159 return -EINVAL;
160
161 /* Size cannot be smaller than the size supported by the device */
162 if (size < bdev_logical_block_size(bdev))
163 return -EINVAL;
164
165 if (!file->private_data)
166 return -EINVAL;
167
168 /* Don't change the size if it is same as current */
169 if (inode->i_blkbits != blksize_bits(size)) {
170 sync_blockdev(bdev);
171 inode->i_blkbits = blksize_bits(size);
172 kill_bdev(bdev);
173 }
174 return 0;
175}
176
177EXPORT_SYMBOL(set_blocksize);
178
179int sb_set_blocksize(struct super_block *sb, int size)
180{
181 if (set_blocksize(sb->s_bdev_file, size))
182 return 0;
183 /* If we get here, we know size is power of two
184 * and it's value is between 512 and PAGE_SIZE */
185 sb->s_blocksize = size;
186 sb->s_blocksize_bits = blksize_bits(size);
187 return sb->s_blocksize;
188}
189
190EXPORT_SYMBOL(sb_set_blocksize);
191
192int sb_min_blocksize(struct super_block *sb, int size)
193{
194 int minsize = bdev_logical_block_size(sb->s_bdev);
195 if (size < minsize)
196 size = minsize;
197 return sb_set_blocksize(sb, size);
198}
199
200EXPORT_SYMBOL(sb_min_blocksize);
201
202int sync_blockdev_nowait(struct block_device *bdev)
203{
204 if (!bdev)
205 return 0;
206 return filemap_flush(bdev->bd_mapping);
207}
208EXPORT_SYMBOL_GPL(sync_blockdev_nowait);
209
210/*
211 * Write out and wait upon all the dirty data associated with a block
212 * device via its mapping. Does not take the superblock lock.
213 */
214int sync_blockdev(struct block_device *bdev)
215{
216 if (!bdev)
217 return 0;
218 return filemap_write_and_wait(bdev->bd_mapping);
219}
220EXPORT_SYMBOL(sync_blockdev);
221
222int sync_blockdev_range(struct block_device *bdev, loff_t lstart, loff_t lend)
223{
224 return filemap_write_and_wait_range(bdev->bd_mapping,
225 lstart, lend);
226}
227EXPORT_SYMBOL(sync_blockdev_range);
228
229/**
230 * bdev_freeze - lock a filesystem and force it into a consistent state
231 * @bdev: blockdevice to lock
232 *
233 * If a superblock is found on this device, we take the s_umount semaphore
234 * on it to make sure nobody unmounts until the snapshot creation is done.
235 * The reference counter (bd_fsfreeze_count) guarantees that only the last
236 * unfreeze process can unfreeze the frozen filesystem actually when multiple
237 * freeze requests arrive simultaneously. It counts up in bdev_freeze() and
238 * count down in bdev_thaw(). When it becomes 0, thaw_bdev() will unfreeze
239 * actually.
240 *
241 * Return: On success zero is returned, negative error code on failure.
242 */
243int bdev_freeze(struct block_device *bdev)
244{
245 int error = 0;
246
247 mutex_lock(&bdev->bd_fsfreeze_mutex);
248
249 if (atomic_inc_return(&bdev->bd_fsfreeze_count) > 1) {
250 mutex_unlock(&bdev->bd_fsfreeze_mutex);
251 return 0;
252 }
253
254 mutex_lock(&bdev->bd_holder_lock);
255 if (bdev->bd_holder_ops && bdev->bd_holder_ops->freeze) {
256 error = bdev->bd_holder_ops->freeze(bdev);
257 lockdep_assert_not_held(&bdev->bd_holder_lock);
258 } else {
259 mutex_unlock(&bdev->bd_holder_lock);
260 error = sync_blockdev(bdev);
261 }
262
263 if (error)
264 atomic_dec(&bdev->bd_fsfreeze_count);
265
266 mutex_unlock(&bdev->bd_fsfreeze_mutex);
267 return error;
268}
269EXPORT_SYMBOL(bdev_freeze);
270
271/**
272 * bdev_thaw - unlock filesystem
273 * @bdev: blockdevice to unlock
274 *
275 * Unlocks the filesystem and marks it writeable again after bdev_freeze().
276 *
277 * Return: On success zero is returned, negative error code on failure.
278 */
279int bdev_thaw(struct block_device *bdev)
280{
281 int error = -EINVAL, nr_freeze;
282
283 mutex_lock(&bdev->bd_fsfreeze_mutex);
284
285 /*
286 * If this returns < 0 it means that @bd_fsfreeze_count was
287 * already 0 and no decrement was performed.
288 */
289 nr_freeze = atomic_dec_if_positive(&bdev->bd_fsfreeze_count);
290 if (nr_freeze < 0)
291 goto out;
292
293 error = 0;
294 if (nr_freeze > 0)
295 goto out;
296
297 mutex_lock(&bdev->bd_holder_lock);
298 if (bdev->bd_holder_ops && bdev->bd_holder_ops->thaw) {
299 error = bdev->bd_holder_ops->thaw(bdev);
300 lockdep_assert_not_held(&bdev->bd_holder_lock);
301 } else {
302 mutex_unlock(&bdev->bd_holder_lock);
303 }
304
305 if (error)
306 atomic_inc(&bdev->bd_fsfreeze_count);
307out:
308 mutex_unlock(&bdev->bd_fsfreeze_mutex);
309 return error;
310}
311EXPORT_SYMBOL(bdev_thaw);
312
313/*
314 * pseudo-fs
315 */
316
317static __cacheline_aligned_in_smp DEFINE_MUTEX(bdev_lock);
318static struct kmem_cache *bdev_cachep __ro_after_init;
319
320static struct inode *bdev_alloc_inode(struct super_block *sb)
321{
322 struct bdev_inode *ei = alloc_inode_sb(sb, bdev_cachep, GFP_KERNEL);
323
324 if (!ei)
325 return NULL;
326 memset(&ei->bdev, 0, sizeof(ei->bdev));
327
328 if (security_bdev_alloc(&ei->bdev)) {
329 kmem_cache_free(bdev_cachep, ei);
330 return NULL;
331 }
332 return &ei->vfs_inode;
333}
334
335static void bdev_free_inode(struct inode *inode)
336{
337 struct block_device *bdev = I_BDEV(inode);
338
339 free_percpu(bdev->bd_stats);
340 kfree(bdev->bd_meta_info);
341 security_bdev_free(bdev);
342
343 if (!bdev_is_partition(bdev)) {
344 if (bdev->bd_disk && bdev->bd_disk->bdi)
345 bdi_put(bdev->bd_disk->bdi);
346 kfree(bdev->bd_disk);
347 }
348
349 if (MAJOR(bdev->bd_dev) == BLOCK_EXT_MAJOR)
350 blk_free_ext_minor(MINOR(bdev->bd_dev));
351
352 kmem_cache_free(bdev_cachep, BDEV_I(inode));
353}
354
355static void init_once(void *data)
356{
357 struct bdev_inode *ei = data;
358
359 inode_init_once(&ei->vfs_inode);
360}
361
362static void bdev_evict_inode(struct inode *inode)
363{
364 truncate_inode_pages_final(&inode->i_data);
365 invalidate_inode_buffers(inode); /* is it needed here? */
366 clear_inode(inode);
367}
368
369static const struct super_operations bdev_sops = {
370 .statfs = simple_statfs,
371 .alloc_inode = bdev_alloc_inode,
372 .free_inode = bdev_free_inode,
373 .drop_inode = generic_delete_inode,
374 .evict_inode = bdev_evict_inode,
375};
376
377static int bd_init_fs_context(struct fs_context *fc)
378{
379 struct pseudo_fs_context *ctx = init_pseudo(fc, BDEVFS_MAGIC);
380 if (!ctx)
381 return -ENOMEM;
382 fc->s_iflags |= SB_I_CGROUPWB;
383 ctx->ops = &bdev_sops;
384 return 0;
385}
386
387static struct file_system_type bd_type = {
388 .name = "bdev",
389 .init_fs_context = bd_init_fs_context,
390 .kill_sb = kill_anon_super,
391};
392
393struct super_block *blockdev_superblock __ro_after_init;
394static struct vfsmount *blockdev_mnt __ro_after_init;
395EXPORT_SYMBOL_GPL(blockdev_superblock);
396
397void __init bdev_cache_init(void)
398{
399 int err;
400
401 bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
402 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
403 SLAB_ACCOUNT|SLAB_PANIC),
404 init_once);
405 err = register_filesystem(&bd_type);
406 if (err)
407 panic("Cannot register bdev pseudo-fs");
408 blockdev_mnt = kern_mount(&bd_type);
409 if (IS_ERR(blockdev_mnt))
410 panic("Cannot create bdev pseudo-fs");
411 blockdev_superblock = blockdev_mnt->mnt_sb; /* For writeback */
412}
413
414struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
415{
416 struct block_device *bdev;
417 struct inode *inode;
418
419 inode = new_inode(blockdev_superblock);
420 if (!inode)
421 return NULL;
422 inode->i_mode = S_IFBLK;
423 inode->i_rdev = 0;
424 inode->i_data.a_ops = &def_blk_aops;
425 mapping_set_gfp_mask(&inode->i_data, GFP_USER);
426
427 bdev = I_BDEV(inode);
428 mutex_init(&bdev->bd_fsfreeze_mutex);
429 spin_lock_init(&bdev->bd_size_lock);
430 mutex_init(&bdev->bd_holder_lock);
431 atomic_set(&bdev->__bd_flags, partno);
432 bdev->bd_mapping = &inode->i_data;
433 bdev->bd_queue = disk->queue;
434 if (partno && bdev_test_flag(disk->part0, BD_HAS_SUBMIT_BIO))
435 bdev_set_flag(bdev, BD_HAS_SUBMIT_BIO);
436 bdev->bd_stats = alloc_percpu(struct disk_stats);
437 if (!bdev->bd_stats) {
438 iput(inode);
439 return NULL;
440 }
441 bdev->bd_disk = disk;
442 return bdev;
443}
444
445void bdev_set_nr_sectors(struct block_device *bdev, sector_t sectors)
446{
447 spin_lock(&bdev->bd_size_lock);
448 i_size_write(BD_INODE(bdev), (loff_t)sectors << SECTOR_SHIFT);
449 bdev->bd_nr_sectors = sectors;
450 spin_unlock(&bdev->bd_size_lock);
451}
452
453void bdev_add(struct block_device *bdev, dev_t dev)
454{
455 struct inode *inode = BD_INODE(bdev);
456 if (bdev_stable_writes(bdev))
457 mapping_set_stable_writes(bdev->bd_mapping);
458 bdev->bd_dev = dev;
459 inode->i_rdev = dev;
460 inode->i_ino = dev;
461 insert_inode_hash(inode);
462}
463
464void bdev_unhash(struct block_device *bdev)
465{
466 remove_inode_hash(BD_INODE(bdev));
467}
468
469void bdev_drop(struct block_device *bdev)
470{
471 iput(BD_INODE(bdev));
472}
473
474long nr_blockdev_pages(void)
475{
476 struct inode *inode;
477 long ret = 0;
478
479 spin_lock(&blockdev_superblock->s_inode_list_lock);
480 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list)
481 ret += inode->i_mapping->nrpages;
482 spin_unlock(&blockdev_superblock->s_inode_list_lock);
483
484 return ret;
485}
486
487/**
488 * bd_may_claim - test whether a block device can be claimed
489 * @bdev: block device of interest
490 * @holder: holder trying to claim @bdev
491 * @hops: holder ops
492 *
493 * Test whether @bdev can be claimed by @holder.
494 *
495 * RETURNS:
496 * %true if @bdev can be claimed, %false otherwise.
497 */
498static bool bd_may_claim(struct block_device *bdev, void *holder,
499 const struct blk_holder_ops *hops)
500{
501 struct block_device *whole = bdev_whole(bdev);
502
503 lockdep_assert_held(&bdev_lock);
504
505 if (bdev->bd_holder) {
506 /*
507 * The same holder can always re-claim.
508 */
509 if (bdev->bd_holder == holder) {
510 if (WARN_ON_ONCE(bdev->bd_holder_ops != hops))
511 return false;
512 return true;
513 }
514 return false;
515 }
516
517 /*
518 * If the whole devices holder is set to bd_may_claim, a partition on
519 * the device is claimed, but not the whole device.
520 */
521 if (whole != bdev &&
522 whole->bd_holder && whole->bd_holder != bd_may_claim)
523 return false;
524 return true;
525}
526
527/**
528 * bd_prepare_to_claim - claim a block device
529 * @bdev: block device of interest
530 * @holder: holder trying to claim @bdev
531 * @hops: holder ops.
532 *
533 * Claim @bdev. This function fails if @bdev is already claimed by another
534 * holder and waits if another claiming is in progress. return, the caller
535 * has ownership of bd_claiming and bd_holder[s].
536 *
537 * RETURNS:
538 * 0 if @bdev can be claimed, -EBUSY otherwise.
539 */
540int bd_prepare_to_claim(struct block_device *bdev, void *holder,
541 const struct blk_holder_ops *hops)
542{
543 struct block_device *whole = bdev_whole(bdev);
544
545 if (WARN_ON_ONCE(!holder))
546 return -EINVAL;
547retry:
548 mutex_lock(&bdev_lock);
549 /* if someone else claimed, fail */
550 if (!bd_may_claim(bdev, holder, hops)) {
551 mutex_unlock(&bdev_lock);
552 return -EBUSY;
553 }
554
555 /* if claiming is already in progress, wait for it to finish */
556 if (whole->bd_claiming) {
557 wait_queue_head_t *wq = __var_waitqueue(&whole->bd_claiming);
558 DEFINE_WAIT(wait);
559
560 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
561 mutex_unlock(&bdev_lock);
562 schedule();
563 finish_wait(wq, &wait);
564 goto retry;
565 }
566
567 /* yay, all mine */
568 whole->bd_claiming = holder;
569 mutex_unlock(&bdev_lock);
570 return 0;
571}
572EXPORT_SYMBOL_GPL(bd_prepare_to_claim); /* only for the loop driver */
573
574static void bd_clear_claiming(struct block_device *whole, void *holder)
575{
576 lockdep_assert_held(&bdev_lock);
577 /* tell others that we're done */
578 BUG_ON(whole->bd_claiming != holder);
579 whole->bd_claiming = NULL;
580 wake_up_var(&whole->bd_claiming);
581}
582
583/**
584 * bd_finish_claiming - finish claiming of a block device
585 * @bdev: block device of interest
586 * @holder: holder that has claimed @bdev
587 * @hops: block device holder operations
588 *
589 * Finish exclusive open of a block device. Mark the device as exlusively
590 * open by the holder and wake up all waiters for exclusive open to finish.
591 */
592static void bd_finish_claiming(struct block_device *bdev, void *holder,
593 const struct blk_holder_ops *hops)
594{
595 struct block_device *whole = bdev_whole(bdev);
596
597 mutex_lock(&bdev_lock);
598 BUG_ON(!bd_may_claim(bdev, holder, hops));
599 /*
600 * Note that for a whole device bd_holders will be incremented twice,
601 * and bd_holder will be set to bd_may_claim before being set to holder
602 */
603 whole->bd_holders++;
604 whole->bd_holder = bd_may_claim;
605 bdev->bd_holders++;
606 mutex_lock(&bdev->bd_holder_lock);
607 bdev->bd_holder = holder;
608 bdev->bd_holder_ops = hops;
609 mutex_unlock(&bdev->bd_holder_lock);
610 bd_clear_claiming(whole, holder);
611 mutex_unlock(&bdev_lock);
612}
613
614/**
615 * bd_abort_claiming - abort claiming of a block device
616 * @bdev: block device of interest
617 * @holder: holder that has claimed @bdev
618 *
619 * Abort claiming of a block device when the exclusive open failed. This can be
620 * also used when exclusive open is not actually desired and we just needed
621 * to block other exclusive openers for a while.
622 */
623void bd_abort_claiming(struct block_device *bdev, void *holder)
624{
625 mutex_lock(&bdev_lock);
626 bd_clear_claiming(bdev_whole(bdev), holder);
627 mutex_unlock(&bdev_lock);
628}
629EXPORT_SYMBOL(bd_abort_claiming);
630
631static void bd_end_claim(struct block_device *bdev, void *holder)
632{
633 struct block_device *whole = bdev_whole(bdev);
634 bool unblock = false;
635
636 /*
637 * Release a claim on the device. The holder fields are protected with
638 * bdev_lock. open_mutex is used to synchronize disk_holder unlinking.
639 */
640 mutex_lock(&bdev_lock);
641 WARN_ON_ONCE(bdev->bd_holder != holder);
642 WARN_ON_ONCE(--bdev->bd_holders < 0);
643 WARN_ON_ONCE(--whole->bd_holders < 0);
644 if (!bdev->bd_holders) {
645 mutex_lock(&bdev->bd_holder_lock);
646 bdev->bd_holder = NULL;
647 bdev->bd_holder_ops = NULL;
648 mutex_unlock(&bdev->bd_holder_lock);
649 if (bdev_test_flag(bdev, BD_WRITE_HOLDER))
650 unblock = true;
651 }
652 if (!whole->bd_holders)
653 whole->bd_holder = NULL;
654 mutex_unlock(&bdev_lock);
655
656 /*
657 * If this was the last claim, remove holder link and unblock evpoll if
658 * it was a write holder.
659 */
660 if (unblock) {
661 disk_unblock_events(bdev->bd_disk);
662 bdev_clear_flag(bdev, BD_WRITE_HOLDER);
663 }
664}
665
666static void blkdev_flush_mapping(struct block_device *bdev)
667{
668 WARN_ON_ONCE(bdev->bd_holders);
669 sync_blockdev(bdev);
670 kill_bdev(bdev);
671 bdev_write_inode(bdev);
672}
673
674static void blkdev_put_whole(struct block_device *bdev)
675{
676 if (atomic_dec_and_test(&bdev->bd_openers))
677 blkdev_flush_mapping(bdev);
678 if (bdev->bd_disk->fops->release)
679 bdev->bd_disk->fops->release(bdev->bd_disk);
680}
681
682static int blkdev_get_whole(struct block_device *bdev, blk_mode_t mode)
683{
684 struct gendisk *disk = bdev->bd_disk;
685 int ret;
686
687 if (disk->fops->open) {
688 ret = disk->fops->open(disk, mode);
689 if (ret) {
690 /* avoid ghost partitions on a removed medium */
691 if (ret == -ENOMEDIUM &&
692 test_bit(GD_NEED_PART_SCAN, &disk->state))
693 bdev_disk_changed(disk, true);
694 return ret;
695 }
696 }
697
698 if (!atomic_read(&bdev->bd_openers))
699 set_init_blocksize(bdev);
700 atomic_inc(&bdev->bd_openers);
701 if (test_bit(GD_NEED_PART_SCAN, &disk->state)) {
702 /*
703 * Only return scanning errors if we are called from contexts
704 * that explicitly want them, e.g. the BLKRRPART ioctl.
705 */
706 ret = bdev_disk_changed(disk, false);
707 if (ret && (mode & BLK_OPEN_STRICT_SCAN)) {
708 blkdev_put_whole(bdev);
709 return ret;
710 }
711 }
712 return 0;
713}
714
715static int blkdev_get_part(struct block_device *part, blk_mode_t mode)
716{
717 struct gendisk *disk = part->bd_disk;
718 int ret;
719
720 ret = blkdev_get_whole(bdev_whole(part), mode);
721 if (ret)
722 return ret;
723
724 ret = -ENXIO;
725 if (!bdev_nr_sectors(part))
726 goto out_blkdev_put;
727
728 if (!atomic_read(&part->bd_openers)) {
729 disk->open_partitions++;
730 set_init_blocksize(part);
731 }
732 atomic_inc(&part->bd_openers);
733 return 0;
734
735out_blkdev_put:
736 blkdev_put_whole(bdev_whole(part));
737 return ret;
738}
739
740int bdev_permission(dev_t dev, blk_mode_t mode, void *holder)
741{
742 int ret;
743
744 ret = devcgroup_check_permission(DEVCG_DEV_BLOCK,
745 MAJOR(dev), MINOR(dev),
746 ((mode & BLK_OPEN_READ) ? DEVCG_ACC_READ : 0) |
747 ((mode & BLK_OPEN_WRITE) ? DEVCG_ACC_WRITE : 0));
748 if (ret)
749 return ret;
750
751 /* Blocking writes requires exclusive opener */
752 if (mode & BLK_OPEN_RESTRICT_WRITES && !holder)
753 return -EINVAL;
754
755 /*
756 * We're using error pointers to indicate to ->release() when we
757 * failed to open that block device. Also this doesn't make sense.
758 */
759 if (WARN_ON_ONCE(IS_ERR(holder)))
760 return -EINVAL;
761
762 return 0;
763}
764
765static void blkdev_put_part(struct block_device *part)
766{
767 struct block_device *whole = bdev_whole(part);
768
769 if (atomic_dec_and_test(&part->bd_openers)) {
770 blkdev_flush_mapping(part);
771 whole->bd_disk->open_partitions--;
772 }
773 blkdev_put_whole(whole);
774}
775
776struct block_device *blkdev_get_no_open(dev_t dev)
777{
778 struct block_device *bdev;
779 struct inode *inode;
780
781 inode = ilookup(blockdev_superblock, dev);
782 if (!inode && IS_ENABLED(CONFIG_BLOCK_LEGACY_AUTOLOAD)) {
783 blk_request_module(dev);
784 inode = ilookup(blockdev_superblock, dev);
785 if (inode)
786 pr_warn_ratelimited(
787"block device autoloading is deprecated and will be removed.\n");
788 }
789 if (!inode)
790 return NULL;
791
792 /* switch from the inode reference to a device mode one: */
793 bdev = &BDEV_I(inode)->bdev;
794 if (!kobject_get_unless_zero(&bdev->bd_device.kobj))
795 bdev = NULL;
796 iput(inode);
797 return bdev;
798}
799
800void blkdev_put_no_open(struct block_device *bdev)
801{
802 put_device(&bdev->bd_device);
803}
804
805static bool bdev_writes_blocked(struct block_device *bdev)
806{
807 return bdev->bd_writers < 0;
808}
809
810static void bdev_block_writes(struct block_device *bdev)
811{
812 bdev->bd_writers--;
813}
814
815static void bdev_unblock_writes(struct block_device *bdev)
816{
817 bdev->bd_writers++;
818}
819
820static bool bdev_may_open(struct block_device *bdev, blk_mode_t mode)
821{
822 if (bdev_allow_write_mounted)
823 return true;
824 /* Writes blocked? */
825 if (mode & BLK_OPEN_WRITE && bdev_writes_blocked(bdev))
826 return false;
827 if (mode & BLK_OPEN_RESTRICT_WRITES && bdev->bd_writers > 0)
828 return false;
829 return true;
830}
831
832static void bdev_claim_write_access(struct block_device *bdev, blk_mode_t mode)
833{
834 if (bdev_allow_write_mounted)
835 return;
836
837 /* Claim exclusive or shared write access. */
838 if (mode & BLK_OPEN_RESTRICT_WRITES)
839 bdev_block_writes(bdev);
840 else if (mode & BLK_OPEN_WRITE)
841 bdev->bd_writers++;
842}
843
844static inline bool bdev_unclaimed(const struct file *bdev_file)
845{
846 return bdev_file->private_data == BDEV_I(bdev_file->f_mapping->host);
847}
848
849static void bdev_yield_write_access(struct file *bdev_file)
850{
851 struct block_device *bdev;
852
853 if (bdev_allow_write_mounted)
854 return;
855
856 if (bdev_unclaimed(bdev_file))
857 return;
858
859 bdev = file_bdev(bdev_file);
860
861 if (bdev_file->f_mode & FMODE_WRITE_RESTRICTED)
862 bdev_unblock_writes(bdev);
863 else if (bdev_file->f_mode & FMODE_WRITE)
864 bdev->bd_writers--;
865}
866
867/**
868 * bdev_open - open a block device
869 * @bdev: block device to open
870 * @mode: open mode (BLK_OPEN_*)
871 * @holder: exclusive holder identifier
872 * @hops: holder operations
873 * @bdev_file: file for the block device
874 *
875 * Open the block device. If @holder is not %NULL, the block device is opened
876 * with exclusive access. Exclusive opens may nest for the same @holder.
877 *
878 * CONTEXT:
879 * Might sleep.
880 *
881 * RETURNS:
882 * zero on success, -errno on failure.
883 */
884int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder,
885 const struct blk_holder_ops *hops, struct file *bdev_file)
886{
887 bool unblock_events = true;
888 struct gendisk *disk = bdev->bd_disk;
889 int ret;
890
891 if (holder) {
892 mode |= BLK_OPEN_EXCL;
893 ret = bd_prepare_to_claim(bdev, holder, hops);
894 if (ret)
895 return ret;
896 } else {
897 if (WARN_ON_ONCE(mode & BLK_OPEN_EXCL))
898 return -EIO;
899 }
900
901 disk_block_events(disk);
902
903 mutex_lock(&disk->open_mutex);
904 ret = -ENXIO;
905 if (!disk_live(disk))
906 goto abort_claiming;
907 if (!try_module_get(disk->fops->owner))
908 goto abort_claiming;
909 ret = -EBUSY;
910 if (!bdev_may_open(bdev, mode))
911 goto put_module;
912 if (bdev_is_partition(bdev))
913 ret = blkdev_get_part(bdev, mode);
914 else
915 ret = blkdev_get_whole(bdev, mode);
916 if (ret)
917 goto put_module;
918 bdev_claim_write_access(bdev, mode);
919 if (holder) {
920 bd_finish_claiming(bdev, holder, hops);
921
922 /*
923 * Block event polling for write claims if requested. Any write
924 * holder makes the write_holder state stick until all are
925 * released. This is good enough and tracking individual
926 * writeable reference is too fragile given the way @mode is
927 * used in blkdev_get/put().
928 */
929 if ((mode & BLK_OPEN_WRITE) &&
930 !bdev_test_flag(bdev, BD_WRITE_HOLDER) &&
931 (disk->event_flags & DISK_EVENT_FLAG_BLOCK_ON_EXCL_WRITE)) {
932 bdev_set_flag(bdev, BD_WRITE_HOLDER);
933 unblock_events = false;
934 }
935 }
936 mutex_unlock(&disk->open_mutex);
937
938 if (unblock_events)
939 disk_unblock_events(disk);
940
941 bdev_file->f_flags |= O_LARGEFILE;
942 bdev_file->f_mode |= FMODE_CAN_ODIRECT;
943 if (bdev_nowait(bdev))
944 bdev_file->f_mode |= FMODE_NOWAIT;
945 if (mode & BLK_OPEN_RESTRICT_WRITES)
946 bdev_file->f_mode |= FMODE_WRITE_RESTRICTED;
947 bdev_file->f_mapping = bdev->bd_mapping;
948 bdev_file->f_wb_err = filemap_sample_wb_err(bdev_file->f_mapping);
949 bdev_file->private_data = holder;
950
951 return 0;
952put_module:
953 module_put(disk->fops->owner);
954abort_claiming:
955 if (holder)
956 bd_abort_claiming(bdev, holder);
957 mutex_unlock(&disk->open_mutex);
958 disk_unblock_events(disk);
959 return ret;
960}
961
962/*
963 * If BLK_OPEN_WRITE_IOCTL is set then this is a historical quirk
964 * associated with the floppy driver where it has allowed ioctls if the
965 * file was opened for writing, but does not allow reads or writes.
966 * Make sure that this quirk is reflected in @f_flags.
967 *
968 * It can also happen if a block device is opened as O_RDWR | O_WRONLY.
969 */
970static unsigned blk_to_file_flags(blk_mode_t mode)
971{
972 unsigned int flags = 0;
973
974 if ((mode & (BLK_OPEN_READ | BLK_OPEN_WRITE)) ==
975 (BLK_OPEN_READ | BLK_OPEN_WRITE))
976 flags |= O_RDWR;
977 else if (mode & BLK_OPEN_WRITE_IOCTL)
978 flags |= O_RDWR | O_WRONLY;
979 else if (mode & BLK_OPEN_WRITE)
980 flags |= O_WRONLY;
981 else if (mode & BLK_OPEN_READ)
982 flags |= O_RDONLY; /* homeopathic, because O_RDONLY is 0 */
983 else
984 WARN_ON_ONCE(true);
985
986 if (mode & BLK_OPEN_NDELAY)
987 flags |= O_NDELAY;
988
989 return flags;
990}
991
992struct file *bdev_file_open_by_dev(dev_t dev, blk_mode_t mode, void *holder,
993 const struct blk_holder_ops *hops)
994{
995 struct file *bdev_file;
996 struct block_device *bdev;
997 unsigned int flags;
998 int ret;
999
1000 ret = bdev_permission(dev, mode, holder);
1001 if (ret)
1002 return ERR_PTR(ret);
1003
1004 bdev = blkdev_get_no_open(dev);
1005 if (!bdev)
1006 return ERR_PTR(-ENXIO);
1007
1008 flags = blk_to_file_flags(mode);
1009 bdev_file = alloc_file_pseudo_noaccount(BD_INODE(bdev),
1010 blockdev_mnt, "", flags | O_LARGEFILE, &def_blk_fops);
1011 if (IS_ERR(bdev_file)) {
1012 blkdev_put_no_open(bdev);
1013 return bdev_file;
1014 }
1015 ihold(BD_INODE(bdev));
1016
1017 ret = bdev_open(bdev, mode, holder, hops, bdev_file);
1018 if (ret) {
1019 /* We failed to open the block device. Let ->release() know. */
1020 bdev_file->private_data = ERR_PTR(ret);
1021 fput(bdev_file);
1022 return ERR_PTR(ret);
1023 }
1024 return bdev_file;
1025}
1026EXPORT_SYMBOL(bdev_file_open_by_dev);
1027
1028struct file *bdev_file_open_by_path(const char *path, blk_mode_t mode,
1029 void *holder,
1030 const struct blk_holder_ops *hops)
1031{
1032 struct file *file;
1033 dev_t dev;
1034 int error;
1035
1036 error = lookup_bdev(path, &dev);
1037 if (error)
1038 return ERR_PTR(error);
1039
1040 file = bdev_file_open_by_dev(dev, mode, holder, hops);
1041 if (!IS_ERR(file) && (mode & BLK_OPEN_WRITE)) {
1042 if (bdev_read_only(file_bdev(file))) {
1043 fput(file);
1044 file = ERR_PTR(-EACCES);
1045 }
1046 }
1047
1048 return file;
1049}
1050EXPORT_SYMBOL(bdev_file_open_by_path);
1051
1052static inline void bd_yield_claim(struct file *bdev_file)
1053{
1054 struct block_device *bdev = file_bdev(bdev_file);
1055 void *holder = bdev_file->private_data;
1056
1057 lockdep_assert_held(&bdev->bd_disk->open_mutex);
1058
1059 if (WARN_ON_ONCE(IS_ERR_OR_NULL(holder)))
1060 return;
1061
1062 if (!bdev_unclaimed(bdev_file))
1063 bd_end_claim(bdev, holder);
1064}
1065
1066void bdev_release(struct file *bdev_file)
1067{
1068 struct block_device *bdev = file_bdev(bdev_file);
1069 void *holder = bdev_file->private_data;
1070 struct gendisk *disk = bdev->bd_disk;
1071
1072 /* We failed to open that block device. */
1073 if (IS_ERR(holder))
1074 goto put_no_open;
1075
1076 /*
1077 * Sync early if it looks like we're the last one. If someone else
1078 * opens the block device between now and the decrement of bd_openers
1079 * then we did a sync that we didn't need to, but that's not the end
1080 * of the world and we want to avoid long (could be several minute)
1081 * syncs while holding the mutex.
1082 */
1083 if (atomic_read(&bdev->bd_openers) == 1)
1084 sync_blockdev(bdev);
1085
1086 mutex_lock(&disk->open_mutex);
1087 bdev_yield_write_access(bdev_file);
1088
1089 if (holder)
1090 bd_yield_claim(bdev_file);
1091
1092 /*
1093 * Trigger event checking and tell drivers to flush MEDIA_CHANGE
1094 * event. This is to ensure detection of media removal commanded
1095 * from userland - e.g. eject(1).
1096 */
1097 disk_flush_events(disk, DISK_EVENT_MEDIA_CHANGE);
1098
1099 if (bdev_is_partition(bdev))
1100 blkdev_put_part(bdev);
1101 else
1102 blkdev_put_whole(bdev);
1103 mutex_unlock(&disk->open_mutex);
1104
1105 module_put(disk->fops->owner);
1106put_no_open:
1107 blkdev_put_no_open(bdev);
1108}
1109
1110/**
1111 * bdev_fput - yield claim to the block device and put the file
1112 * @bdev_file: open block device
1113 *
1114 * Yield claim on the block device and put the file. Ensure that the
1115 * block device can be reclaimed before the file is closed which is a
1116 * deferred operation.
1117 */
1118void bdev_fput(struct file *bdev_file)
1119{
1120 if (WARN_ON_ONCE(bdev_file->f_op != &def_blk_fops))
1121 return;
1122
1123 if (bdev_file->private_data) {
1124 struct block_device *bdev = file_bdev(bdev_file);
1125 struct gendisk *disk = bdev->bd_disk;
1126
1127 mutex_lock(&disk->open_mutex);
1128 bdev_yield_write_access(bdev_file);
1129 bd_yield_claim(bdev_file);
1130 /*
1131 * Tell release we already gave up our hold on the
1132 * device and if write restrictions are available that
1133 * we already gave up write access to the device.
1134 */
1135 bdev_file->private_data = BDEV_I(bdev_file->f_mapping->host);
1136 mutex_unlock(&disk->open_mutex);
1137 }
1138
1139 fput(bdev_file);
1140}
1141EXPORT_SYMBOL(bdev_fput);
1142
1143/**
1144 * lookup_bdev() - Look up a struct block_device by name.
1145 * @pathname: Name of the block device in the filesystem.
1146 * @dev: Pointer to the block device's dev_t, if found.
1147 *
1148 * Lookup the block device's dev_t at @pathname in the current
1149 * namespace if possible and return it in @dev.
1150 *
1151 * Context: May sleep.
1152 * Return: 0 if succeeded, negative errno otherwise.
1153 */
1154int lookup_bdev(const char *pathname, dev_t *dev)
1155{
1156 struct inode *inode;
1157 struct path path;
1158 int error;
1159
1160 if (!pathname || !*pathname)
1161 return -EINVAL;
1162
1163 error = kern_path(pathname, LOOKUP_FOLLOW, &path);
1164 if (error)
1165 return error;
1166
1167 inode = d_backing_inode(path.dentry);
1168 error = -ENOTBLK;
1169 if (!S_ISBLK(inode->i_mode))
1170 goto out_path_put;
1171 error = -EACCES;
1172 if (!may_open_dev(&path))
1173 goto out_path_put;
1174
1175 *dev = inode->i_rdev;
1176 error = 0;
1177out_path_put:
1178 path_put(&path);
1179 return error;
1180}
1181EXPORT_SYMBOL(lookup_bdev);
1182
1183/**
1184 * bdev_mark_dead - mark a block device as dead
1185 * @bdev: block device to operate on
1186 * @surprise: indicate a surprise removal
1187 *
1188 * Tell the file system that this devices or media is dead. If @surprise is set
1189 * to %true the device or media is already gone, if not we are preparing for an
1190 * orderly removal.
1191 *
1192 * This calls into the file system, which then typicall syncs out all dirty data
1193 * and writes back inodes and then invalidates any cached data in the inodes on
1194 * the file system. In addition we also invalidate the block device mapping.
1195 */
1196void bdev_mark_dead(struct block_device *bdev, bool surprise)
1197{
1198 mutex_lock(&bdev->bd_holder_lock);
1199 if (bdev->bd_holder_ops && bdev->bd_holder_ops->mark_dead)
1200 bdev->bd_holder_ops->mark_dead(bdev, surprise);
1201 else {
1202 mutex_unlock(&bdev->bd_holder_lock);
1203 sync_blockdev(bdev);
1204 }
1205
1206 invalidate_bdev(bdev);
1207}
1208/*
1209 * New drivers should not use this directly. There are some drivers however
1210 * that needs this for historical reasons. For example, the DASD driver has
1211 * historically had a shutdown to offline mode that doesn't actually remove the
1212 * gendisk that otherwise looks a lot like a safe device removal.
1213 */
1214EXPORT_SYMBOL_GPL(bdev_mark_dead);
1215
1216void sync_bdevs(bool wait)
1217{
1218 struct inode *inode, *old_inode = NULL;
1219
1220 spin_lock(&blockdev_superblock->s_inode_list_lock);
1221 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
1222 struct address_space *mapping = inode->i_mapping;
1223 struct block_device *bdev;
1224
1225 spin_lock(&inode->i_lock);
1226 if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
1227 mapping->nrpages == 0) {
1228 spin_unlock(&inode->i_lock);
1229 continue;
1230 }
1231 __iget(inode);
1232 spin_unlock(&inode->i_lock);
1233 spin_unlock(&blockdev_superblock->s_inode_list_lock);
1234 /*
1235 * We hold a reference to 'inode' so it couldn't have been
1236 * removed from s_inodes list while we dropped the
1237 * s_inode_list_lock We cannot iput the inode now as we can
1238 * be holding the last reference and we cannot iput it under
1239 * s_inode_list_lock. So we keep the reference and iput it
1240 * later.
1241 */
1242 iput(old_inode);
1243 old_inode = inode;
1244 bdev = I_BDEV(inode);
1245
1246 mutex_lock(&bdev->bd_disk->open_mutex);
1247 if (!atomic_read(&bdev->bd_openers)) {
1248 ; /* skip */
1249 } else if (wait) {
1250 /*
1251 * We keep the error status of individual mapping so
1252 * that applications can catch the writeback error using
1253 * fsync(2). See filemap_fdatawait_keep_errors() for
1254 * details.
1255 */
1256 filemap_fdatawait_keep_errors(inode->i_mapping);
1257 } else {
1258 filemap_fdatawrite(inode->i_mapping);
1259 }
1260 mutex_unlock(&bdev->bd_disk->open_mutex);
1261
1262 spin_lock(&blockdev_superblock->s_inode_list_lock);
1263 }
1264 spin_unlock(&blockdev_superblock->s_inode_list_lock);
1265 iput(old_inode);
1266}
1267
1268/*
1269 * Handle STATX_{DIOALIGN, WRITE_ATOMIC} for block devices.
1270 */
1271void bdev_statx(struct path *path, struct kstat *stat,
1272 u32 request_mask)
1273{
1274 struct inode *backing_inode;
1275 struct block_device *bdev;
1276
1277 if (!(request_mask & (STATX_DIOALIGN | STATX_WRITE_ATOMIC)))
1278 return;
1279
1280 backing_inode = d_backing_inode(path->dentry);
1281
1282 /*
1283 * Note that backing_inode is the inode of a block device node file,
1284 * not the block device's internal inode. Therefore it is *not* valid
1285 * to use I_BDEV() here; the block device has to be looked up by i_rdev
1286 * instead.
1287 */
1288 bdev = blkdev_get_no_open(backing_inode->i_rdev);
1289 if (!bdev)
1290 return;
1291
1292 if (request_mask & STATX_DIOALIGN) {
1293 stat->dio_mem_align = bdev_dma_alignment(bdev) + 1;
1294 stat->dio_offset_align = bdev_logical_block_size(bdev);
1295 stat->result_mask |= STATX_DIOALIGN;
1296 }
1297
1298 if (request_mask & STATX_WRITE_ATOMIC && bdev_can_atomic_write(bdev)) {
1299 struct request_queue *bd_queue = bdev->bd_queue;
1300
1301 generic_fill_statx_atomic_writes(stat,
1302 queue_atomic_write_unit_min_bytes(bd_queue),
1303 queue_atomic_write_unit_max_bytes(bd_queue));
1304 }
1305
1306 blkdev_put_no_open(bdev);
1307}
1308
1309bool disk_live(struct gendisk *disk)
1310{
1311 return !inode_unhashed(BD_INODE(disk->part0));
1312}
1313EXPORT_SYMBOL_GPL(disk_live);
1314
1315unsigned int block_size(struct block_device *bdev)
1316{
1317 return 1 << BD_INODE(bdev)->i_blkbits;
1318}
1319EXPORT_SYMBOL_GPL(block_size);
1320
1321static int __init setup_bdev_allow_write_mounted(char *str)
1322{
1323 if (kstrtobool(str, &bdev_allow_write_mounted))
1324 pr_warn("Invalid option string for bdev_allow_write_mounted:"
1325 " '%s'\n", str);
1326 return 1;
1327}
1328__setup("bdev_allow_write_mounted=", setup_bdev_allow_write_mounted);