Line data Source code
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/part_stat.h>
28 : #include <linux/uaccess.h>
29 : #include <linux/stat.h>
30 : #include "../fs/internal.h"
31 : #include "blk.h"
32 :
33 : struct bdev_inode {
34 : struct block_device bdev;
35 : struct inode vfs_inode;
36 : };
37 :
38 : static inline struct bdev_inode *BDEV_I(struct inode *inode)
39 : {
40 0 : return container_of(inode, struct bdev_inode, vfs_inode);
41 : }
42 :
43 0 : struct block_device *I_BDEV(struct inode *inode)
44 : {
45 0 : return &BDEV_I(inode)->bdev;
46 : }
47 : EXPORT_SYMBOL(I_BDEV);
48 :
49 0 : static void bdev_write_inode(struct block_device *bdev)
50 : {
51 0 : struct inode *inode = bdev->bd_inode;
52 : int ret;
53 :
54 0 : spin_lock(&inode->i_lock);
55 0 : while (inode->i_state & I_DIRTY) {
56 0 : spin_unlock(&inode->i_lock);
57 0 : ret = write_inode_now(inode, true);
58 0 : if (ret)
59 0 : pr_warn_ratelimited(
60 : "VFS: Dirty inode writeback failed for block device %pg (err=%d).\n",
61 : bdev, ret);
62 0 : spin_lock(&inode->i_lock);
63 : }
64 0 : spin_unlock(&inode->i_lock);
65 0 : }
66 :
67 : /* Kill _all_ buffers and pagecache , dirty or not.. */
68 0 : static void kill_bdev(struct block_device *bdev)
69 : {
70 0 : struct address_space *mapping = bdev->bd_inode->i_mapping;
71 :
72 0 : if (mapping_empty(mapping))
73 : return;
74 :
75 0 : invalidate_bh_lrus();
76 0 : truncate_inode_pages(mapping, 0);
77 : }
78 :
79 : /* Invalidate clean unused buffers and pagecache. */
80 0 : void invalidate_bdev(struct block_device *bdev)
81 : {
82 0 : struct address_space *mapping = bdev->bd_inode->i_mapping;
83 :
84 0 : if (mapping->nrpages) {
85 0 : invalidate_bh_lrus();
86 0 : lru_add_drain_all(); /* make sure all lru add caches are flushed */
87 0 : invalidate_mapping_pages(mapping, 0, -1);
88 : }
89 0 : }
90 : EXPORT_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 : */
96 0 : int truncate_bdev_range(struct block_device *bdev, fmode_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 0 : if (!(mode & FMODE_EXCL)) {
105 0 : int err = bd_prepare_to_claim(bdev, truncate_bdev_range);
106 0 : if (err)
107 : goto invalidate;
108 : }
109 :
110 0 : truncate_inode_pages_range(bdev->bd_inode->i_mapping, lstart, lend);
111 0 : if (!(mode & FMODE_EXCL))
112 : bd_abort_claiming(bdev, truncate_bdev_range);
113 : return 0;
114 :
115 : invalidate:
116 : /*
117 : * Someone else has handle exclusively open. Try invalidating instead.
118 : * The 'end' argument is inclusive so the rounding is safe.
119 : */
120 0 : return invalidate_inode_pages2_range(bdev->bd_inode->i_mapping,
121 0 : lstart >> PAGE_SHIFT,
122 0 : lend >> PAGE_SHIFT);
123 : }
124 :
125 0 : static void set_init_blocksize(struct block_device *bdev)
126 : {
127 0 : unsigned int bsize = bdev_logical_block_size(bdev);
128 0 : loff_t size = i_size_read(bdev->bd_inode);
129 :
130 0 : while (bsize < PAGE_SIZE) {
131 0 : if (size & bsize)
132 : break;
133 0 : bsize <<= 1;
134 : }
135 0 : bdev->bd_inode->i_blkbits = blksize_bits(bsize);
136 0 : }
137 :
138 0 : int set_blocksize(struct block_device *bdev, int size)
139 : {
140 : /* Size must be a power of two, and between 512 and PAGE_SIZE */
141 0 : 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 0 : if (size < bdev_logical_block_size(bdev))
146 : return -EINVAL;
147 :
148 : /* Don't change the size if it is same as current */
149 0 : if (bdev->bd_inode->i_blkbits != blksize_bits(size)) {
150 0 : sync_blockdev(bdev);
151 0 : bdev->bd_inode->i_blkbits = blksize_bits(size);
152 0 : kill_bdev(bdev);
153 : }
154 : return 0;
155 : }
156 :
157 : EXPORT_SYMBOL(set_blocksize);
158 :
159 0 : int sb_set_blocksize(struct super_block *sb, int size)
160 : {
161 0 : 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 0 : sb->s_blocksize = size;
166 0 : sb->s_blocksize_bits = blksize_bits(size);
167 0 : return sb->s_blocksize;
168 : }
169 :
170 : EXPORT_SYMBOL(sb_set_blocksize);
171 :
172 0 : int sb_min_blocksize(struct super_block *sb, int size)
173 : {
174 0 : int minsize = bdev_logical_block_size(sb->s_bdev);
175 0 : if (size < minsize)
176 0 : size = minsize;
177 0 : return sb_set_blocksize(sb, size);
178 : }
179 :
180 : EXPORT_SYMBOL(sb_min_blocksize);
181 :
182 17 : int sync_blockdev_nowait(struct block_device *bdev)
183 : {
184 17 : if (!bdev)
185 : return 0;
186 0 : return filemap_flush(bdev->bd_inode->i_mapping);
187 : }
188 : EXPORT_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 : */
194 17 : int sync_blockdev(struct block_device *bdev)
195 : {
196 17 : if (!bdev)
197 : return 0;
198 0 : return filemap_write_and_wait(bdev->bd_inode->i_mapping);
199 : }
200 : EXPORT_SYMBOL(sync_blockdev);
201 :
202 0 : int sync_blockdev_range(struct block_device *bdev, loff_t lstart, loff_t lend)
203 : {
204 0 : return filemap_write_and_wait_range(bdev->bd_inode->i_mapping,
205 : lstart, lend);
206 : }
207 : EXPORT_SYMBOL(sync_blockdev_range);
208 :
209 : /*
210 : * Write out and wait upon all dirty data associated with this
211 : * device. Filesystem data as well as the underlying block
212 : * device. Takes the superblock lock.
213 : */
214 0 : int fsync_bdev(struct block_device *bdev)
215 : {
216 0 : struct super_block *sb = get_super(bdev);
217 0 : if (sb) {
218 0 : int res = sync_filesystem(sb);
219 0 : drop_super(sb);
220 0 : return res;
221 : }
222 : return sync_blockdev(bdev);
223 : }
224 : EXPORT_SYMBOL(fsync_bdev);
225 :
226 : /**
227 : * freeze_bdev - lock a filesystem and force it into a consistent state
228 : * @bdev: blockdevice to lock
229 : *
230 : * If a superblock is found on this device, we take the s_umount semaphore
231 : * on it to make sure nobody unmounts until the snapshot creation is done.
232 : * The reference counter (bd_fsfreeze_count) guarantees that only the last
233 : * unfreeze process can unfreeze the frozen filesystem actually when multiple
234 : * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
235 : * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
236 : * actually.
237 : */
238 0 : int freeze_bdev(struct block_device *bdev)
239 : {
240 : struct super_block *sb;
241 0 : int error = 0;
242 :
243 0 : mutex_lock(&bdev->bd_fsfreeze_mutex);
244 0 : if (++bdev->bd_fsfreeze_count > 1)
245 : goto done;
246 :
247 0 : sb = get_active_super(bdev);
248 0 : if (!sb)
249 : goto sync;
250 0 : if (sb->s_op->freeze_super)
251 0 : error = sb->s_op->freeze_super(sb);
252 : else
253 0 : error = freeze_super(sb);
254 0 : deactivate_super(sb);
255 :
256 0 : if (error) {
257 0 : bdev->bd_fsfreeze_count--;
258 0 : goto done;
259 : }
260 0 : bdev->bd_fsfreeze_sb = sb;
261 :
262 : sync:
263 : sync_blockdev(bdev);
264 : done:
265 0 : mutex_unlock(&bdev->bd_fsfreeze_mutex);
266 0 : return error;
267 : }
268 : EXPORT_SYMBOL(freeze_bdev);
269 :
270 : /**
271 : * thaw_bdev - unlock filesystem
272 : * @bdev: blockdevice to unlock
273 : *
274 : * Unlocks the filesystem and marks it writeable again after freeze_bdev().
275 : */
276 0 : int thaw_bdev(struct block_device *bdev)
277 : {
278 : struct super_block *sb;
279 0 : int error = -EINVAL;
280 :
281 0 : mutex_lock(&bdev->bd_fsfreeze_mutex);
282 0 : if (!bdev->bd_fsfreeze_count)
283 : goto out;
284 :
285 0 : error = 0;
286 0 : if (--bdev->bd_fsfreeze_count > 0)
287 : goto out;
288 :
289 0 : sb = bdev->bd_fsfreeze_sb;
290 0 : if (!sb)
291 : goto out;
292 :
293 0 : if (sb->s_op->thaw_super)
294 0 : error = sb->s_op->thaw_super(sb);
295 : else
296 0 : error = thaw_super(sb);
297 0 : if (error)
298 0 : bdev->bd_fsfreeze_count++;
299 : else
300 0 : bdev->bd_fsfreeze_sb = NULL;
301 : out:
302 0 : mutex_unlock(&bdev->bd_fsfreeze_mutex);
303 0 : return error;
304 : }
305 : EXPORT_SYMBOL(thaw_bdev);
306 :
307 : /*
308 : * pseudo-fs
309 : */
310 :
311 : static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
312 : static struct kmem_cache * bdev_cachep __read_mostly;
313 :
314 1 : static struct inode *bdev_alloc_inode(struct super_block *sb)
315 : {
316 2 : struct bdev_inode *ei = alloc_inode_sb(sb, bdev_cachep, GFP_KERNEL);
317 :
318 1 : if (!ei)
319 : return NULL;
320 1 : memset(&ei->bdev, 0, sizeof(ei->bdev));
321 1 : return &ei->vfs_inode;
322 : }
323 :
324 0 : static void bdev_free_inode(struct inode *inode)
325 : {
326 0 : struct block_device *bdev = I_BDEV(inode);
327 :
328 0 : free_percpu(bdev->bd_stats);
329 0 : kfree(bdev->bd_meta_info);
330 :
331 0 : if (!bdev_is_partition(bdev)) {
332 0 : if (bdev->bd_disk && bdev->bd_disk->bdi)
333 0 : bdi_put(bdev->bd_disk->bdi);
334 0 : kfree(bdev->bd_disk);
335 : }
336 :
337 0 : if (MAJOR(bdev->bd_dev) == BLOCK_EXT_MAJOR)
338 0 : blk_free_ext_minor(MINOR(bdev->bd_dev));
339 :
340 0 : kmem_cache_free(bdev_cachep, BDEV_I(inode));
341 0 : }
342 :
343 11 : static void init_once(void *data)
344 : {
345 11 : struct bdev_inode *ei = data;
346 :
347 11 : inode_init_once(&ei->vfs_inode);
348 11 : }
349 :
350 0 : static void bdev_evict_inode(struct inode *inode)
351 : {
352 0 : truncate_inode_pages_final(&inode->i_data);
353 0 : invalidate_inode_buffers(inode); /* is it needed here? */
354 0 : clear_inode(inode);
355 0 : }
356 :
357 : static const struct super_operations bdev_sops = {
358 : .statfs = simple_statfs,
359 : .alloc_inode = bdev_alloc_inode,
360 : .free_inode = bdev_free_inode,
361 : .drop_inode = generic_delete_inode,
362 : .evict_inode = bdev_evict_inode,
363 : };
364 :
365 1 : static int bd_init_fs_context(struct fs_context *fc)
366 : {
367 1 : struct pseudo_fs_context *ctx = init_pseudo(fc, BDEVFS_MAGIC);
368 1 : if (!ctx)
369 : return -ENOMEM;
370 1 : fc->s_iflags |= SB_I_CGROUPWB;
371 1 : ctx->ops = &bdev_sops;
372 1 : return 0;
373 : }
374 :
375 : static struct file_system_type bd_type = {
376 : .name = "bdev",
377 : .init_fs_context = bd_init_fs_context,
378 : .kill_sb = kill_anon_super,
379 : };
380 :
381 : struct super_block *blockdev_superblock __read_mostly;
382 : EXPORT_SYMBOL_GPL(blockdev_superblock);
383 :
384 1 : void __init bdev_cache_init(void)
385 : {
386 : int err;
387 : static struct vfsmount *bd_mnt;
388 :
389 1 : bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
390 : 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
391 : SLAB_MEM_SPREAD|SLAB_ACCOUNT|SLAB_PANIC),
392 : init_once);
393 1 : err = register_filesystem(&bd_type);
394 1 : if (err)
395 0 : panic("Cannot register bdev pseudo-fs");
396 1 : bd_mnt = kern_mount(&bd_type);
397 2 : if (IS_ERR(bd_mnt))
398 0 : panic("Cannot create bdev pseudo-fs");
399 1 : blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */
400 1 : }
401 :
402 0 : struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
403 : {
404 : struct block_device *bdev;
405 : struct inode *inode;
406 :
407 0 : inode = new_inode(blockdev_superblock);
408 0 : if (!inode)
409 : return NULL;
410 0 : inode->i_mode = S_IFBLK;
411 0 : inode->i_rdev = 0;
412 0 : inode->i_data.a_ops = &def_blk_aops;
413 0 : mapping_set_gfp_mask(&inode->i_data, GFP_USER);
414 :
415 0 : bdev = I_BDEV(inode);
416 0 : mutex_init(&bdev->bd_fsfreeze_mutex);
417 0 : spin_lock_init(&bdev->bd_size_lock);
418 0 : bdev->bd_partno = partno;
419 0 : bdev->bd_inode = inode;
420 0 : bdev->bd_queue = disk->queue;
421 0 : bdev->bd_stats = alloc_percpu(struct disk_stats);
422 0 : if (!bdev->bd_stats) {
423 0 : iput(inode);
424 0 : return NULL;
425 : }
426 0 : bdev->bd_disk = disk;
427 0 : return bdev;
428 : }
429 :
430 0 : void bdev_add(struct block_device *bdev, dev_t dev)
431 : {
432 0 : bdev->bd_dev = dev;
433 0 : bdev->bd_inode->i_rdev = dev;
434 0 : bdev->bd_inode->i_ino = dev;
435 0 : insert_inode_hash(bdev->bd_inode);
436 0 : }
437 :
438 2 : long nr_blockdev_pages(void)
439 : {
440 : struct inode *inode;
441 2 : long ret = 0;
442 :
443 4 : spin_lock(&blockdev_superblock->s_inode_list_lock);
444 4 : list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list)
445 2 : ret += inode->i_mapping->nrpages;
446 4 : spin_unlock(&blockdev_superblock->s_inode_list_lock);
447 :
448 2 : return ret;
449 : }
450 :
451 : /**
452 : * bd_may_claim - test whether a block device can be claimed
453 : * @bdev: block device of interest
454 : * @whole: whole block device containing @bdev, may equal @bdev
455 : * @holder: holder trying to claim @bdev
456 : *
457 : * Test whether @bdev can be claimed by @holder.
458 : *
459 : * CONTEXT:
460 : * spin_lock(&bdev_lock).
461 : *
462 : * RETURNS:
463 : * %true if @bdev can be claimed, %false otherwise.
464 : */
465 0 : static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
466 : void *holder)
467 : {
468 0 : if (bdev->bd_holder == holder)
469 : return true; /* already a holder */
470 0 : else if (bdev->bd_holder != NULL)
471 : return false; /* held by someone else */
472 0 : else if (whole == bdev)
473 : return true; /* is a whole device which isn't held */
474 :
475 0 : else if (whole->bd_holder == bd_may_claim)
476 : return true; /* is a partition of a device that is being partitioned */
477 0 : else if (whole->bd_holder != NULL)
478 : return false; /* is a partition of a held device */
479 : else
480 0 : return true; /* is a partition of an un-held device */
481 : }
482 :
483 : /**
484 : * bd_prepare_to_claim - claim a block device
485 : * @bdev: block device of interest
486 : * @holder: holder trying to claim @bdev
487 : *
488 : * Claim @bdev. This function fails if @bdev is already claimed by another
489 : * holder and waits if another claiming is in progress. return, the caller
490 : * has ownership of bd_claiming and bd_holder[s].
491 : *
492 : * RETURNS:
493 : * 0 if @bdev can be claimed, -EBUSY otherwise.
494 : */
495 0 : int bd_prepare_to_claim(struct block_device *bdev, void *holder)
496 : {
497 0 : struct block_device *whole = bdev_whole(bdev);
498 :
499 0 : if (WARN_ON_ONCE(!holder))
500 : return -EINVAL;
501 : retry:
502 0 : spin_lock(&bdev_lock);
503 : /* if someone else claimed, fail */
504 0 : if (!bd_may_claim(bdev, whole, holder)) {
505 0 : spin_unlock(&bdev_lock);
506 0 : return -EBUSY;
507 : }
508 :
509 : /* if claiming is already in progress, wait for it to finish */
510 0 : if (whole->bd_claiming) {
511 0 : wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
512 0 : DEFINE_WAIT(wait);
513 :
514 0 : prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
515 0 : spin_unlock(&bdev_lock);
516 0 : schedule();
517 0 : finish_wait(wq, &wait);
518 : goto retry;
519 : }
520 :
521 : /* yay, all mine */
522 0 : whole->bd_claiming = holder;
523 0 : spin_unlock(&bdev_lock);
524 0 : return 0;
525 : }
526 : EXPORT_SYMBOL_GPL(bd_prepare_to_claim); /* only for the loop driver */
527 :
528 0 : static void bd_clear_claiming(struct block_device *whole, void *holder)
529 : {
530 : lockdep_assert_held(&bdev_lock);
531 : /* tell others that we're done */
532 0 : BUG_ON(whole->bd_claiming != holder);
533 0 : whole->bd_claiming = NULL;
534 0 : wake_up_bit(&whole->bd_claiming, 0);
535 0 : }
536 :
537 : /**
538 : * bd_finish_claiming - finish claiming of a block device
539 : * @bdev: block device of interest
540 : * @holder: holder that has claimed @bdev
541 : *
542 : * Finish exclusive open of a block device. Mark the device as exlusively
543 : * open by the holder and wake up all waiters for exclusive open to finish.
544 : */
545 0 : static void bd_finish_claiming(struct block_device *bdev, void *holder)
546 : {
547 0 : struct block_device *whole = bdev_whole(bdev);
548 :
549 0 : spin_lock(&bdev_lock);
550 0 : BUG_ON(!bd_may_claim(bdev, whole, holder));
551 : /*
552 : * Note that for a whole device bd_holders will be incremented twice,
553 : * and bd_holder will be set to bd_may_claim before being set to holder
554 : */
555 0 : whole->bd_holders++;
556 0 : whole->bd_holder = bd_may_claim;
557 0 : bdev->bd_holders++;
558 0 : bdev->bd_holder = holder;
559 0 : bd_clear_claiming(whole, holder);
560 0 : spin_unlock(&bdev_lock);
561 0 : }
562 :
563 : /**
564 : * bd_abort_claiming - abort claiming of a block device
565 : * @bdev: block device of interest
566 : * @holder: holder that has claimed @bdev
567 : *
568 : * Abort claiming of a block device when the exclusive open failed. This can be
569 : * also used when exclusive open is not actually desired and we just needed
570 : * to block other exclusive openers for a while.
571 : */
572 0 : void bd_abort_claiming(struct block_device *bdev, void *holder)
573 : {
574 0 : spin_lock(&bdev_lock);
575 0 : bd_clear_claiming(bdev_whole(bdev), holder);
576 0 : spin_unlock(&bdev_lock);
577 0 : }
578 : EXPORT_SYMBOL(bd_abort_claiming);
579 :
580 0 : static void blkdev_flush_mapping(struct block_device *bdev)
581 : {
582 0 : WARN_ON_ONCE(bdev->bd_holders);
583 0 : sync_blockdev(bdev);
584 0 : kill_bdev(bdev);
585 0 : bdev_write_inode(bdev);
586 0 : }
587 :
588 0 : static int blkdev_get_whole(struct block_device *bdev, fmode_t mode)
589 : {
590 0 : struct gendisk *disk = bdev->bd_disk;
591 : int ret;
592 :
593 0 : if (disk->fops->open) {
594 0 : ret = disk->fops->open(bdev, mode);
595 0 : if (ret) {
596 : /* avoid ghost partitions on a removed medium */
597 0 : if (ret == -ENOMEDIUM &&
598 0 : test_bit(GD_NEED_PART_SCAN, &disk->state))
599 0 : bdev_disk_changed(disk, true);
600 : return ret;
601 : }
602 : }
603 :
604 0 : if (!atomic_read(&bdev->bd_openers))
605 0 : set_init_blocksize(bdev);
606 0 : if (test_bit(GD_NEED_PART_SCAN, &disk->state))
607 0 : bdev_disk_changed(disk, false);
608 0 : atomic_inc(&bdev->bd_openers);
609 0 : return 0;
610 : }
611 :
612 0 : static void blkdev_put_whole(struct block_device *bdev, fmode_t mode)
613 : {
614 0 : if (atomic_dec_and_test(&bdev->bd_openers))
615 0 : blkdev_flush_mapping(bdev);
616 0 : if (bdev->bd_disk->fops->release)
617 0 : bdev->bd_disk->fops->release(bdev->bd_disk, mode);
618 0 : }
619 :
620 0 : static int blkdev_get_part(struct block_device *part, fmode_t mode)
621 : {
622 0 : struct gendisk *disk = part->bd_disk;
623 : int ret;
624 :
625 0 : if (atomic_read(&part->bd_openers))
626 : goto done;
627 :
628 0 : ret = blkdev_get_whole(bdev_whole(part), mode);
629 0 : if (ret)
630 : return ret;
631 :
632 0 : ret = -ENXIO;
633 0 : if (!bdev_nr_sectors(part))
634 : goto out_blkdev_put;
635 :
636 0 : disk->open_partitions++;
637 0 : set_init_blocksize(part);
638 : done:
639 0 : atomic_inc(&part->bd_openers);
640 0 : return 0;
641 :
642 : out_blkdev_put:
643 0 : blkdev_put_whole(bdev_whole(part), mode);
644 0 : return ret;
645 : }
646 :
647 0 : static void blkdev_put_part(struct block_device *part, fmode_t mode)
648 : {
649 0 : struct block_device *whole = bdev_whole(part);
650 :
651 0 : if (!atomic_dec_and_test(&part->bd_openers))
652 : return;
653 0 : blkdev_flush_mapping(part);
654 0 : whole->bd_disk->open_partitions--;
655 0 : blkdev_put_whole(whole, mode);
656 : }
657 :
658 0 : struct block_device *blkdev_get_no_open(dev_t dev)
659 : {
660 : struct block_device *bdev;
661 : struct inode *inode;
662 :
663 0 : inode = ilookup(blockdev_superblock, dev);
664 0 : if (!inode && IS_ENABLED(CONFIG_BLOCK_LEGACY_AUTOLOAD)) {
665 0 : blk_request_module(dev);
666 0 : inode = ilookup(blockdev_superblock, dev);
667 0 : if (inode)
668 0 : pr_warn_ratelimited(
669 : "block device autoloading is deprecated and will be removed.\n");
670 : }
671 0 : if (!inode)
672 : return NULL;
673 :
674 : /* switch from the inode reference to a device mode one: */
675 0 : bdev = &BDEV_I(inode)->bdev;
676 0 : if (!kobject_get_unless_zero(&bdev->bd_device.kobj))
677 0 : bdev = NULL;
678 0 : iput(inode);
679 0 : return bdev;
680 : }
681 :
682 0 : void blkdev_put_no_open(struct block_device *bdev)
683 : {
684 0 : put_device(&bdev->bd_device);
685 0 : }
686 :
687 : /**
688 : * blkdev_get_by_dev - open a block device by device number
689 : * @dev: device number of block device to open
690 : * @mode: FMODE_* mask
691 : * @holder: exclusive holder identifier
692 : *
693 : * Open the block device described by device number @dev. If @mode includes
694 : * %FMODE_EXCL, the block device is opened with exclusive access. Specifying
695 : * %FMODE_EXCL with a %NULL @holder is invalid. Exclusive opens may nest for
696 : * the same @holder.
697 : *
698 : * Use this interface ONLY if you really do not have anything better - i.e. when
699 : * you are behind a truly sucky interface and all you are given is a device
700 : * number. Everything else should use blkdev_get_by_path().
701 : *
702 : * CONTEXT:
703 : * Might sleep.
704 : *
705 : * RETURNS:
706 : * Reference to the block_device on success, ERR_PTR(-errno) on failure.
707 : */
708 0 : struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
709 : {
710 0 : bool unblock_events = true;
711 : struct block_device *bdev;
712 : struct gendisk *disk;
713 : int ret;
714 :
715 0 : ret = devcgroup_check_permission(DEVCG_DEV_BLOCK,
716 0 : MAJOR(dev), MINOR(dev),
717 0 : ((mode & FMODE_READ) ? DEVCG_ACC_READ : 0) |
718 0 : ((mode & FMODE_WRITE) ? DEVCG_ACC_WRITE : 0));
719 : if (ret)
720 : return ERR_PTR(ret);
721 :
722 0 : bdev = blkdev_get_no_open(dev);
723 0 : if (!bdev)
724 : return ERR_PTR(-ENXIO);
725 0 : disk = bdev->bd_disk;
726 :
727 0 : if (mode & FMODE_EXCL) {
728 0 : ret = bd_prepare_to_claim(bdev, holder);
729 0 : if (ret)
730 : goto put_blkdev;
731 : }
732 :
733 0 : disk_block_events(disk);
734 :
735 0 : mutex_lock(&disk->open_mutex);
736 0 : ret = -ENXIO;
737 0 : if (!disk_live(disk))
738 : goto abort_claiming;
739 0 : if (!try_module_get(disk->fops->owner))
740 : goto abort_claiming;
741 0 : if (bdev_is_partition(bdev))
742 0 : ret = blkdev_get_part(bdev, mode);
743 : else
744 0 : ret = blkdev_get_whole(bdev, mode);
745 0 : if (ret)
746 : goto put_module;
747 0 : if (mode & FMODE_EXCL) {
748 0 : bd_finish_claiming(bdev, holder);
749 :
750 : /*
751 : * Block event polling for write claims if requested. Any write
752 : * holder makes the write_holder state stick until all are
753 : * released. This is good enough and tracking individual
754 : * writeable reference is too fragile given the way @mode is
755 : * used in blkdev_get/put().
756 : */
757 0 : if ((mode & FMODE_WRITE) && !bdev->bd_write_holder &&
758 0 : (disk->event_flags & DISK_EVENT_FLAG_BLOCK_ON_EXCL_WRITE)) {
759 0 : bdev->bd_write_holder = true;
760 0 : unblock_events = false;
761 : }
762 : }
763 0 : mutex_unlock(&disk->open_mutex);
764 :
765 0 : if (unblock_events)
766 0 : disk_unblock_events(disk);
767 : return bdev;
768 : put_module:
769 : module_put(disk->fops->owner);
770 : abort_claiming:
771 0 : if (mode & FMODE_EXCL)
772 : bd_abort_claiming(bdev, holder);
773 0 : mutex_unlock(&disk->open_mutex);
774 0 : disk_unblock_events(disk);
775 : put_blkdev:
776 0 : blkdev_put_no_open(bdev);
777 0 : return ERR_PTR(ret);
778 : }
779 : EXPORT_SYMBOL(blkdev_get_by_dev);
780 :
781 : /**
782 : * blkdev_get_by_path - open a block device by name
783 : * @path: path to the block device to open
784 : * @mode: FMODE_* mask
785 : * @holder: exclusive holder identifier
786 : *
787 : * Open the block device described by the device file at @path. If @mode
788 : * includes %FMODE_EXCL, the block device is opened with exclusive access.
789 : * Specifying %FMODE_EXCL with a %NULL @holder is invalid. Exclusive opens may
790 : * nest for the same @holder.
791 : *
792 : * CONTEXT:
793 : * Might sleep.
794 : *
795 : * RETURNS:
796 : * Reference to the block_device on success, ERR_PTR(-errno) on failure.
797 : */
798 0 : struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
799 : void *holder)
800 : {
801 : struct block_device *bdev;
802 : dev_t dev;
803 : int error;
804 :
805 0 : error = lookup_bdev(path, &dev);
806 0 : if (error)
807 0 : return ERR_PTR(error);
808 :
809 0 : bdev = blkdev_get_by_dev(dev, mode, holder);
810 0 : if (!IS_ERR(bdev) && (mode & FMODE_WRITE) && bdev_read_only(bdev)) {
811 0 : blkdev_put(bdev, mode);
812 0 : return ERR_PTR(-EACCES);
813 : }
814 :
815 : return bdev;
816 : }
817 : EXPORT_SYMBOL(blkdev_get_by_path);
818 :
819 0 : void blkdev_put(struct block_device *bdev, fmode_t mode)
820 : {
821 0 : struct gendisk *disk = bdev->bd_disk;
822 :
823 : /*
824 : * Sync early if it looks like we're the last one. If someone else
825 : * opens the block device between now and the decrement of bd_openers
826 : * then we did a sync that we didn't need to, but that's not the end
827 : * of the world and we want to avoid long (could be several minute)
828 : * syncs while holding the mutex.
829 : */
830 0 : if (atomic_read(&bdev->bd_openers) == 1)
831 : sync_blockdev(bdev);
832 :
833 0 : mutex_lock(&disk->open_mutex);
834 0 : if (mode & FMODE_EXCL) {
835 0 : struct block_device *whole = bdev_whole(bdev);
836 : bool bdev_free;
837 :
838 : /*
839 : * Release a claim on the device. The holder fields
840 : * are protected with bdev_lock. open_mutex is to
841 : * synchronize disk_holder unlinking.
842 : */
843 0 : spin_lock(&bdev_lock);
844 :
845 0 : WARN_ON_ONCE(--bdev->bd_holders < 0);
846 0 : WARN_ON_ONCE(--whole->bd_holders < 0);
847 :
848 0 : if ((bdev_free = !bdev->bd_holders))
849 0 : bdev->bd_holder = NULL;
850 0 : if (!whole->bd_holders)
851 0 : whole->bd_holder = NULL;
852 :
853 0 : spin_unlock(&bdev_lock);
854 :
855 : /*
856 : * If this was the last claim, remove holder link and
857 : * unblock evpoll if it was a write holder.
858 : */
859 0 : if (bdev_free && bdev->bd_write_holder) {
860 0 : disk_unblock_events(disk);
861 0 : bdev->bd_write_holder = false;
862 : }
863 : }
864 :
865 : /*
866 : * Trigger event checking and tell drivers to flush MEDIA_CHANGE
867 : * event. This is to ensure detection of media removal commanded
868 : * from userland - e.g. eject(1).
869 : */
870 0 : disk_flush_events(disk, DISK_EVENT_MEDIA_CHANGE);
871 :
872 0 : if (bdev_is_partition(bdev))
873 0 : blkdev_put_part(bdev, mode);
874 : else
875 0 : blkdev_put_whole(bdev, mode);
876 0 : mutex_unlock(&disk->open_mutex);
877 :
878 0 : module_put(disk->fops->owner);
879 0 : blkdev_put_no_open(bdev);
880 0 : }
881 : EXPORT_SYMBOL(blkdev_put);
882 :
883 : /**
884 : * lookup_bdev() - Look up a struct block_device by name.
885 : * @pathname: Name of the block device in the filesystem.
886 : * @dev: Pointer to the block device's dev_t, if found.
887 : *
888 : * Lookup the block device's dev_t at @pathname in the current
889 : * namespace if possible and return it in @dev.
890 : *
891 : * Context: May sleep.
892 : * Return: 0 if succeeded, negative errno otherwise.
893 : */
894 0 : int lookup_bdev(const char *pathname, dev_t *dev)
895 : {
896 : struct inode *inode;
897 : struct path path;
898 : int error;
899 :
900 0 : if (!pathname || !*pathname)
901 : return -EINVAL;
902 :
903 0 : error = kern_path(pathname, LOOKUP_FOLLOW, &path);
904 0 : if (error)
905 : return error;
906 :
907 0 : inode = d_backing_inode(path.dentry);
908 0 : error = -ENOTBLK;
909 0 : if (!S_ISBLK(inode->i_mode))
910 : goto out_path_put;
911 0 : error = -EACCES;
912 0 : if (!may_open_dev(&path))
913 : goto out_path_put;
914 :
915 0 : *dev = inode->i_rdev;
916 0 : error = 0;
917 : out_path_put:
918 0 : path_put(&path);
919 0 : return error;
920 : }
921 : EXPORT_SYMBOL(lookup_bdev);
922 :
923 0 : int __invalidate_device(struct block_device *bdev, bool kill_dirty)
924 : {
925 0 : struct super_block *sb = get_super(bdev);
926 0 : int res = 0;
927 :
928 0 : if (sb) {
929 : /*
930 : * no need to lock the super, get_super holds the
931 : * read mutex so the filesystem cannot go away
932 : * under us (->put_super runs with the write lock
933 : * hold).
934 : */
935 0 : shrink_dcache_sb(sb);
936 0 : res = invalidate_inodes(sb, kill_dirty);
937 0 : drop_super(sb);
938 : }
939 0 : invalidate_bdev(bdev);
940 0 : return res;
941 : }
942 : EXPORT_SYMBOL(__invalidate_device);
943 :
944 0 : void sync_bdevs(bool wait)
945 : {
946 0 : struct inode *inode, *old_inode = NULL;
947 :
948 0 : spin_lock(&blockdev_superblock->s_inode_list_lock);
949 0 : list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
950 0 : struct address_space *mapping = inode->i_mapping;
951 : struct block_device *bdev;
952 :
953 0 : spin_lock(&inode->i_lock);
954 0 : if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
955 0 : mapping->nrpages == 0) {
956 0 : spin_unlock(&inode->i_lock);
957 0 : continue;
958 : }
959 0 : __iget(inode);
960 0 : spin_unlock(&inode->i_lock);
961 0 : spin_unlock(&blockdev_superblock->s_inode_list_lock);
962 : /*
963 : * We hold a reference to 'inode' so it couldn't have been
964 : * removed from s_inodes list while we dropped the
965 : * s_inode_list_lock We cannot iput the inode now as we can
966 : * be holding the last reference and we cannot iput it under
967 : * s_inode_list_lock. So we keep the reference and iput it
968 : * later.
969 : */
970 0 : iput(old_inode);
971 0 : old_inode = inode;
972 0 : bdev = I_BDEV(inode);
973 :
974 0 : mutex_lock(&bdev->bd_disk->open_mutex);
975 0 : if (!atomic_read(&bdev->bd_openers)) {
976 : ; /* skip */
977 0 : } else if (wait) {
978 : /*
979 : * We keep the error status of individual mapping so
980 : * that applications can catch the writeback error using
981 : * fsync(2). See filemap_fdatawait_keep_errors() for
982 : * details.
983 : */
984 0 : filemap_fdatawait_keep_errors(inode->i_mapping);
985 : } else {
986 0 : filemap_fdatawrite(inode->i_mapping);
987 : }
988 0 : mutex_unlock(&bdev->bd_disk->open_mutex);
989 :
990 0 : spin_lock(&blockdev_superblock->s_inode_list_lock);
991 : }
992 0 : spin_unlock(&blockdev_superblock->s_inode_list_lock);
993 0 : iput(old_inode);
994 0 : }
995 :
996 : /*
997 : * Handle STATX_DIOALIGN for block devices.
998 : *
999 : * Note that the inode passed to this is the inode of a block device node file,
1000 : * not the block device's internal inode. Therefore it is *not* valid to use
1001 : * I_BDEV() here; the block device has to be looked up by i_rdev instead.
1002 : */
1003 0 : void bdev_statx_dioalign(struct inode *inode, struct kstat *stat)
1004 : {
1005 : struct block_device *bdev;
1006 :
1007 0 : bdev = blkdev_get_no_open(inode->i_rdev);
1008 0 : if (!bdev)
1009 : return;
1010 :
1011 0 : stat->dio_mem_align = bdev_dma_alignment(bdev) + 1;
1012 0 : stat->dio_offset_align = bdev_logical_block_size(bdev);
1013 0 : stat->result_mask |= STATX_DIOALIGN;
1014 :
1015 : blkdev_put_no_open(bdev);
1016 : }
|
