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1/*
2 * linux/fs/block_dev.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
6 */
7
8#include <linux/init.h>
9#include <linux/mm.h>
10#include <linux/fcntl.h>
11#include <linux/slab.h>
12#include <linux/kmod.h>
13#include <linux/major.h>
14#include <linux/device_cgroup.h>
15#include <linux/highmem.h>
16#include <linux/blkdev.h>
17#include <linux/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/pagevec.h>
23#include <linux/writeback.h>
24#include <linux/mpage.h>
25#include <linux/mount.h>
26#include <linux/uio.h>
27#include <linux/namei.h>
28#include <linux/log2.h>
29#include <linux/cleancache.h>
30#include <asm/uaccess.h>
31#include "internal.h"
32
33struct bdev_inode {
34 struct block_device bdev;
35 struct inode vfs_inode;
36};
37
38static const struct address_space_operations def_blk_aops;
39
40static inline struct bdev_inode *BDEV_I(struct inode *inode)
41{
42 return container_of(inode, struct bdev_inode, vfs_inode);
43}
44
45inline struct block_device *I_BDEV(struct inode *inode)
46{
47 return &BDEV_I(inode)->bdev;
48}
49EXPORT_SYMBOL(I_BDEV);
50
51/*
52 * Move the inode from its current bdi to a new bdi. If the inode is dirty we
53 * need to move it onto the dirty list of @dst so that the inode is always on
54 * the right list.
55 */
56static void bdev_inode_switch_bdi(struct inode *inode,
57 struct backing_dev_info *dst)
58{
59 struct backing_dev_info *old = inode->i_data.backing_dev_info;
60
61 if (unlikely(dst == old)) /* deadlock avoidance */
62 return;
63 bdi_lock_two(&old->wb, &dst->wb);
64 spin_lock(&inode->i_lock);
65 inode->i_data.backing_dev_info = dst;
66 if (inode->i_state & I_DIRTY)
67 list_move(&inode->i_wb_list, &dst->wb.b_dirty);
68 spin_unlock(&inode->i_lock);
69 spin_unlock(&old->wb.list_lock);
70 spin_unlock(&dst->wb.list_lock);
71}
72
73sector_t blkdev_max_block(struct block_device *bdev)
74{
75 sector_t retval = ~((sector_t)0);
76 loff_t sz = i_size_read(bdev->bd_inode);
77
78 if (sz) {
79 unsigned int size = block_size(bdev);
80 unsigned int sizebits = blksize_bits(size);
81 retval = (sz >> sizebits);
82 }
83 return retval;
84}
85
86/* Kill _all_ buffers and pagecache , dirty or not.. */
87void kill_bdev(struct block_device *bdev)
88{
89 struct address_space *mapping = bdev->bd_inode->i_mapping;
90
91 if (mapping->nrpages == 0)
92 return;
93
94 invalidate_bh_lrus();
95 truncate_inode_pages(mapping, 0);
96}
97EXPORT_SYMBOL(kill_bdev);
98
99/* Invalidate clean unused buffers and pagecache. */
100void invalidate_bdev(struct block_device *bdev)
101{
102 struct address_space *mapping = bdev->bd_inode->i_mapping;
103
104 if (mapping->nrpages == 0)
105 return;
106
107 invalidate_bh_lrus();
108 lru_add_drain_all(); /* make sure all lru add caches are flushed */
109 invalidate_mapping_pages(mapping, 0, -1);
110 /* 99% of the time, we don't need to flush the cleancache on the bdev.
111 * But, for the strange corners, lets be cautious
112 */
113 cleancache_invalidate_inode(mapping);
114}
115EXPORT_SYMBOL(invalidate_bdev);
116
117int set_blocksize(struct block_device *bdev, int size)
118{
119 /* Size must be a power of two, and between 512 and PAGE_SIZE */
120 if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
121 return -EINVAL;
122
123 /* Size cannot be smaller than the size supported by the device */
124 if (size < bdev_logical_block_size(bdev))
125 return -EINVAL;
126
127 /* Don't change the size if it is same as current */
128 if (bdev->bd_block_size != size) {
129 sync_blockdev(bdev);
130 bdev->bd_block_size = size;
131 bdev->bd_inode->i_blkbits = blksize_bits(size);
132 kill_bdev(bdev);
133 }
134 return 0;
135}
136
137EXPORT_SYMBOL(set_blocksize);
138
139int sb_set_blocksize(struct super_block *sb, int size)
140{
141 if (set_blocksize(sb->s_bdev, size))
142 return 0;
143 /* If we get here, we know size is power of two
144 * and it's value is between 512 and PAGE_SIZE */
145 sb->s_blocksize = size;
146 sb->s_blocksize_bits = blksize_bits(size);
147 return sb->s_blocksize;
148}
149
150EXPORT_SYMBOL(sb_set_blocksize);
151
152int sb_min_blocksize(struct super_block *sb, int size)
153{
154 int minsize = bdev_logical_block_size(sb->s_bdev);
155 if (size < minsize)
156 size = minsize;
157 return sb_set_blocksize(sb, size);
158}
159
160EXPORT_SYMBOL(sb_min_blocksize);
161
162static int
163blkdev_get_block(struct inode *inode, sector_t iblock,
164 struct buffer_head *bh, int create)
165{
166 if (iblock >= blkdev_max_block(I_BDEV(inode))) {
167 if (create)
168 return -EIO;
169
170 /*
171 * for reads, we're just trying to fill a partial page.
172 * return a hole, they will have to call get_block again
173 * before they can fill it, and they will get -EIO at that
174 * time
175 */
176 return 0;
177 }
178 bh->b_bdev = I_BDEV(inode);
179 bh->b_blocknr = iblock;
180 set_buffer_mapped(bh);
181 return 0;
182}
183
184static int
185blkdev_get_blocks(struct inode *inode, sector_t iblock,
186 struct buffer_head *bh, int create)
187{
188 sector_t end_block = blkdev_max_block(I_BDEV(inode));
189 unsigned long max_blocks = bh->b_size >> inode->i_blkbits;
190
191 if ((iblock + max_blocks) > end_block) {
192 max_blocks = end_block - iblock;
193 if ((long)max_blocks <= 0) {
194 if (create)
195 return -EIO; /* write fully beyond EOF */
196 /*
197 * It is a read which is fully beyond EOF. We return
198 * a !buffer_mapped buffer
199 */
200 max_blocks = 0;
201 }
202 }
203
204 bh->b_bdev = I_BDEV(inode);
205 bh->b_blocknr = iblock;
206 bh->b_size = max_blocks << inode->i_blkbits;
207 if (max_blocks)
208 set_buffer_mapped(bh);
209 return 0;
210}
211
212static ssize_t
213blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
214 loff_t offset, unsigned long nr_segs)
215{
216 struct file *file = iocb->ki_filp;
217 struct inode *inode = file->f_mapping->host;
218
219 return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset,
220 nr_segs, blkdev_get_blocks, NULL, NULL, 0);
221}
222
223int __sync_blockdev(struct block_device *bdev, int wait)
224{
225 if (!bdev)
226 return 0;
227 if (!wait)
228 return filemap_flush(bdev->bd_inode->i_mapping);
229 return filemap_write_and_wait(bdev->bd_inode->i_mapping);
230}
231
232/*
233 * Write out and wait upon all the dirty data associated with a block
234 * device via its mapping. Does not take the superblock lock.
235 */
236int sync_blockdev(struct block_device *bdev)
237{
238 return __sync_blockdev(bdev, 1);
239}
240EXPORT_SYMBOL(sync_blockdev);
241
242/*
243 * Write out and wait upon all dirty data associated with this
244 * device. Filesystem data as well as the underlying block
245 * device. Takes the superblock lock.
246 */
247int fsync_bdev(struct block_device *bdev)
248{
249 struct super_block *sb = get_super(bdev);
250 if (sb) {
251 int res = sync_filesystem(sb);
252 drop_super(sb);
253 return res;
254 }
255 return sync_blockdev(bdev);
256}
257EXPORT_SYMBOL(fsync_bdev);
258
259/**
260 * freeze_bdev -- lock a filesystem and force it into a consistent state
261 * @bdev: blockdevice to lock
262 *
263 * If a superblock is found on this device, we take the s_umount semaphore
264 * on it to make sure nobody unmounts until the snapshot creation is done.
265 * The reference counter (bd_fsfreeze_count) guarantees that only the last
266 * unfreeze process can unfreeze the frozen filesystem actually when multiple
267 * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
268 * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
269 * actually.
270 */
271struct super_block *freeze_bdev(struct block_device *bdev)
272{
273 struct super_block *sb;
274 int error = 0;
275
276 mutex_lock(&bdev->bd_fsfreeze_mutex);
277 if (++bdev->bd_fsfreeze_count > 1) {
278 /*
279 * We don't even need to grab a reference - the first call
280 * to freeze_bdev grab an active reference and only the last
281 * thaw_bdev drops it.
282 */
283 sb = get_super(bdev);
284 drop_super(sb);
285 mutex_unlock(&bdev->bd_fsfreeze_mutex);
286 return sb;
287 }
288
289 sb = get_active_super(bdev);
290 if (!sb)
291 goto out;
292 error = freeze_super(sb);
293 if (error) {
294 deactivate_super(sb);
295 bdev->bd_fsfreeze_count--;
296 mutex_unlock(&bdev->bd_fsfreeze_mutex);
297 return ERR_PTR(error);
298 }
299 deactivate_super(sb);
300 out:
301 sync_blockdev(bdev);
302 mutex_unlock(&bdev->bd_fsfreeze_mutex);
303 return sb; /* thaw_bdev releases s->s_umount */
304}
305EXPORT_SYMBOL(freeze_bdev);
306
307/**
308 * thaw_bdev -- unlock filesystem
309 * @bdev: blockdevice to unlock
310 * @sb: associated superblock
311 *
312 * Unlocks the filesystem and marks it writeable again after freeze_bdev().
313 */
314int thaw_bdev(struct block_device *bdev, struct super_block *sb)
315{
316 int error = -EINVAL;
317
318 mutex_lock(&bdev->bd_fsfreeze_mutex);
319 if (!bdev->bd_fsfreeze_count)
320 goto out;
321
322 error = 0;
323 if (--bdev->bd_fsfreeze_count > 0)
324 goto out;
325
326 if (!sb)
327 goto out;
328
329 error = thaw_super(sb);
330 if (error) {
331 bdev->bd_fsfreeze_count++;
332 mutex_unlock(&bdev->bd_fsfreeze_mutex);
333 return error;
334 }
335out:
336 mutex_unlock(&bdev->bd_fsfreeze_mutex);
337 return 0;
338}
339EXPORT_SYMBOL(thaw_bdev);
340
341static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
342{
343 return block_write_full_page(page, blkdev_get_block, wbc);
344}
345
346static int blkdev_readpage(struct file * file, struct page * page)
347{
348 return block_read_full_page(page, blkdev_get_block);
349}
350
351static int blkdev_write_begin(struct file *file, struct address_space *mapping,
352 loff_t pos, unsigned len, unsigned flags,
353 struct page **pagep, void **fsdata)
354{
355 return block_write_begin(mapping, pos, len, flags, pagep,
356 blkdev_get_block);
357}
358
359static int blkdev_write_end(struct file *file, struct address_space *mapping,
360 loff_t pos, unsigned len, unsigned copied,
361 struct page *page, void *fsdata)
362{
363 int ret;
364 ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
365
366 unlock_page(page);
367 page_cache_release(page);
368
369 return ret;
370}
371
372/*
373 * private llseek:
374 * for a block special file file->f_path.dentry->d_inode->i_size is zero
375 * so we compute the size by hand (just as in block_read/write above)
376 */
377static loff_t block_llseek(struct file *file, loff_t offset, int origin)
378{
379 struct inode *bd_inode = file->f_mapping->host;
380 loff_t size;
381 loff_t retval;
382
383 mutex_lock(&bd_inode->i_mutex);
384 size = i_size_read(bd_inode);
385
386 retval = -EINVAL;
387 switch (origin) {
388 case SEEK_END:
389 offset += size;
390 break;
391 case SEEK_CUR:
392 offset += file->f_pos;
393 case SEEK_SET:
394 break;
395 default:
396 goto out;
397 }
398 if (offset >= 0 && offset <= size) {
399 if (offset != file->f_pos) {
400 file->f_pos = offset;
401 }
402 retval = offset;
403 }
404out:
405 mutex_unlock(&bd_inode->i_mutex);
406 return retval;
407}
408
409int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
410{
411 struct inode *bd_inode = filp->f_mapping->host;
412 struct block_device *bdev = I_BDEV(bd_inode);
413 int error;
414
415 error = filemap_write_and_wait_range(filp->f_mapping, start, end);
416 if (error)
417 return error;
418
419 /*
420 * There is no need to serialise calls to blkdev_issue_flush with
421 * i_mutex and doing so causes performance issues with concurrent
422 * O_SYNC writers to a block device.
423 */
424 error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL);
425 if (error == -EOPNOTSUPP)
426 error = 0;
427
428 return error;
429}
430EXPORT_SYMBOL(blkdev_fsync);
431
432/*
433 * pseudo-fs
434 */
435
436static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
437static struct kmem_cache * bdev_cachep __read_mostly;
438
439static struct inode *bdev_alloc_inode(struct super_block *sb)
440{
441 struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
442 if (!ei)
443 return NULL;
444 return &ei->vfs_inode;
445}
446
447static void bdev_i_callback(struct rcu_head *head)
448{
449 struct inode *inode = container_of(head, struct inode, i_rcu);
450 struct bdev_inode *bdi = BDEV_I(inode);
451
452 kmem_cache_free(bdev_cachep, bdi);
453}
454
455static void bdev_destroy_inode(struct inode *inode)
456{
457 call_rcu(&inode->i_rcu, bdev_i_callback);
458}
459
460static void init_once(void *foo)
461{
462 struct bdev_inode *ei = (struct bdev_inode *) foo;
463 struct block_device *bdev = &ei->bdev;
464
465 memset(bdev, 0, sizeof(*bdev));
466 mutex_init(&bdev->bd_mutex);
467 INIT_LIST_HEAD(&bdev->bd_inodes);
468 INIT_LIST_HEAD(&bdev->bd_list);
469#ifdef CONFIG_SYSFS
470 INIT_LIST_HEAD(&bdev->bd_holder_disks);
471#endif
472 inode_init_once(&ei->vfs_inode);
473 /* Initialize mutex for freeze. */
474 mutex_init(&bdev->bd_fsfreeze_mutex);
475}
476
477static inline void __bd_forget(struct inode *inode)
478{
479 list_del_init(&inode->i_devices);
480 inode->i_bdev = NULL;
481 inode->i_mapping = &inode->i_data;
482}
483
484static void bdev_evict_inode(struct inode *inode)
485{
486 struct block_device *bdev = &BDEV_I(inode)->bdev;
487 struct list_head *p;
488 truncate_inode_pages(&inode->i_data, 0);
489 invalidate_inode_buffers(inode); /* is it needed here? */
490 clear_inode(inode);
491 spin_lock(&bdev_lock);
492 while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) {
493 __bd_forget(list_entry(p, struct inode, i_devices));
494 }
495 list_del_init(&bdev->bd_list);
496 spin_unlock(&bdev_lock);
497}
498
499static const struct super_operations bdev_sops = {
500 .statfs = simple_statfs,
501 .alloc_inode = bdev_alloc_inode,
502 .destroy_inode = bdev_destroy_inode,
503 .drop_inode = generic_delete_inode,
504 .evict_inode = bdev_evict_inode,
505};
506
507static struct dentry *bd_mount(struct file_system_type *fs_type,
508 int flags, const char *dev_name, void *data)
509{
510 return mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC);
511}
512
513static struct file_system_type bd_type = {
514 .name = "bdev",
515 .mount = bd_mount,
516 .kill_sb = kill_anon_super,
517};
518
519static struct super_block *blockdev_superblock __read_mostly;
520
521void __init bdev_cache_init(void)
522{
523 int err;
524 static struct vfsmount *bd_mnt;
525
526 bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
527 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
528 SLAB_MEM_SPREAD|SLAB_PANIC),
529 init_once);
530 err = register_filesystem(&bd_type);
531 if (err)
532 panic("Cannot register bdev pseudo-fs");
533 bd_mnt = kern_mount(&bd_type);
534 if (IS_ERR(bd_mnt))
535 panic("Cannot create bdev pseudo-fs");
536 blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */
537}
538
539/*
540 * Most likely _very_ bad one - but then it's hardly critical for small
541 * /dev and can be fixed when somebody will need really large one.
542 * Keep in mind that it will be fed through icache hash function too.
543 */
544static inline unsigned long hash(dev_t dev)
545{
546 return MAJOR(dev)+MINOR(dev);
547}
548
549static int bdev_test(struct inode *inode, void *data)
550{
551 return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
552}
553
554static int bdev_set(struct inode *inode, void *data)
555{
556 BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
557 return 0;
558}
559
560static LIST_HEAD(all_bdevs);
561
562struct block_device *bdget(dev_t dev)
563{
564 struct block_device *bdev;
565 struct inode *inode;
566
567 inode = iget5_locked(blockdev_superblock, hash(dev),
568 bdev_test, bdev_set, &dev);
569
570 if (!inode)
571 return NULL;
572
573 bdev = &BDEV_I(inode)->bdev;
574
575 if (inode->i_state & I_NEW) {
576 bdev->bd_contains = NULL;
577 bdev->bd_super = NULL;
578 bdev->bd_inode = inode;
579 bdev->bd_block_size = (1 << inode->i_blkbits);
580 bdev->bd_part_count = 0;
581 bdev->bd_invalidated = 0;
582 inode->i_mode = S_IFBLK;
583 inode->i_rdev = dev;
584 inode->i_bdev = bdev;
585 inode->i_data.a_ops = &def_blk_aops;
586 mapping_set_gfp_mask(&inode->i_data, GFP_USER);
587 inode->i_data.backing_dev_info = &default_backing_dev_info;
588 spin_lock(&bdev_lock);
589 list_add(&bdev->bd_list, &all_bdevs);
590 spin_unlock(&bdev_lock);
591 unlock_new_inode(inode);
592 }
593 return bdev;
594}
595
596EXPORT_SYMBOL(bdget);
597
598/**
599 * bdgrab -- Grab a reference to an already referenced block device
600 * @bdev: Block device to grab a reference to.
601 */
602struct block_device *bdgrab(struct block_device *bdev)
603{
604 ihold(bdev->bd_inode);
605 return bdev;
606}
607
608long nr_blockdev_pages(void)
609{
610 struct block_device *bdev;
611 long ret = 0;
612 spin_lock(&bdev_lock);
613 list_for_each_entry(bdev, &all_bdevs, bd_list) {
614 ret += bdev->bd_inode->i_mapping->nrpages;
615 }
616 spin_unlock(&bdev_lock);
617 return ret;
618}
619
620void bdput(struct block_device *bdev)
621{
622 iput(bdev->bd_inode);
623}
624
625EXPORT_SYMBOL(bdput);
626
627static struct block_device *bd_acquire(struct inode *inode)
628{
629 struct block_device *bdev;
630
631 spin_lock(&bdev_lock);
632 bdev = inode->i_bdev;
633 if (bdev) {
634 ihold(bdev->bd_inode);
635 spin_unlock(&bdev_lock);
636 return bdev;
637 }
638 spin_unlock(&bdev_lock);
639
640 bdev = bdget(inode->i_rdev);
641 if (bdev) {
642 spin_lock(&bdev_lock);
643 if (!inode->i_bdev) {
644 /*
645 * We take an additional reference to bd_inode,
646 * and it's released in clear_inode() of inode.
647 * So, we can access it via ->i_mapping always
648 * without igrab().
649 */
650 ihold(bdev->bd_inode);
651 inode->i_bdev = bdev;
652 inode->i_mapping = bdev->bd_inode->i_mapping;
653 list_add(&inode->i_devices, &bdev->bd_inodes);
654 }
655 spin_unlock(&bdev_lock);
656 }
657 return bdev;
658}
659
660static inline int sb_is_blkdev_sb(struct super_block *sb)
661{
662 return sb == blockdev_superblock;
663}
664
665/* Call when you free inode */
666
667void bd_forget(struct inode *inode)
668{
669 struct block_device *bdev = NULL;
670
671 spin_lock(&bdev_lock);
672 if (inode->i_bdev) {
673 if (!sb_is_blkdev_sb(inode->i_sb))
674 bdev = inode->i_bdev;
675 __bd_forget(inode);
676 }
677 spin_unlock(&bdev_lock);
678
679 if (bdev)
680 iput(bdev->bd_inode);
681}
682
683/**
684 * bd_may_claim - test whether a block device can be claimed
685 * @bdev: block device of interest
686 * @whole: whole block device containing @bdev, may equal @bdev
687 * @holder: holder trying to claim @bdev
688 *
689 * Test whether @bdev can be claimed by @holder.
690 *
691 * CONTEXT:
692 * spin_lock(&bdev_lock).
693 *
694 * RETURNS:
695 * %true if @bdev can be claimed, %false otherwise.
696 */
697static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
698 void *holder)
699{
700 if (bdev->bd_holder == holder)
701 return true; /* already a holder */
702 else if (bdev->bd_holder != NULL)
703 return false; /* held by someone else */
704 else if (bdev->bd_contains == bdev)
705 return true; /* is a whole device which isn't held */
706
707 else if (whole->bd_holder == bd_may_claim)
708 return true; /* is a partition of a device that is being partitioned */
709 else if (whole->bd_holder != NULL)
710 return false; /* is a partition of a held device */
711 else
712 return true; /* is a partition of an un-held device */
713}
714
715/**
716 * bd_prepare_to_claim - prepare to claim a block device
717 * @bdev: block device of interest
718 * @whole: the whole device containing @bdev, may equal @bdev
719 * @holder: holder trying to claim @bdev
720 *
721 * Prepare to claim @bdev. This function fails if @bdev is already
722 * claimed by another holder and waits if another claiming is in
723 * progress. This function doesn't actually claim. On successful
724 * return, the caller has ownership of bd_claiming and bd_holder[s].
725 *
726 * CONTEXT:
727 * spin_lock(&bdev_lock). Might release bdev_lock, sleep and regrab
728 * it multiple times.
729 *
730 * RETURNS:
731 * 0 if @bdev can be claimed, -EBUSY otherwise.
732 */
733static int bd_prepare_to_claim(struct block_device *bdev,
734 struct block_device *whole, void *holder)
735{
736retry:
737 /* if someone else claimed, fail */
738 if (!bd_may_claim(bdev, whole, holder))
739 return -EBUSY;
740
741 /* if claiming is already in progress, wait for it to finish */
742 if (whole->bd_claiming) {
743 wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
744 DEFINE_WAIT(wait);
745
746 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
747 spin_unlock(&bdev_lock);
748 schedule();
749 finish_wait(wq, &wait);
750 spin_lock(&bdev_lock);
751 goto retry;
752 }
753
754 /* yay, all mine */
755 return 0;
756}
757
758/**
759 * bd_start_claiming - start claiming a block device
760 * @bdev: block device of interest
761 * @holder: holder trying to claim @bdev
762 *
763 * @bdev is about to be opened exclusively. Check @bdev can be opened
764 * exclusively and mark that an exclusive open is in progress. Each
765 * successful call to this function must be matched with a call to
766 * either bd_finish_claiming() or bd_abort_claiming() (which do not
767 * fail).
768 *
769 * This function is used to gain exclusive access to the block device
770 * without actually causing other exclusive open attempts to fail. It
771 * should be used when the open sequence itself requires exclusive
772 * access but may subsequently fail.
773 *
774 * CONTEXT:
775 * Might sleep.
776 *
777 * RETURNS:
778 * Pointer to the block device containing @bdev on success, ERR_PTR()
779 * value on failure.
780 */
781static struct block_device *bd_start_claiming(struct block_device *bdev,
782 void *holder)
783{
784 struct gendisk *disk;
785 struct block_device *whole;
786 int partno, err;
787
788 might_sleep();
789
790 /*
791 * @bdev might not have been initialized properly yet, look up
792 * and grab the outer block device the hard way.
793 */
794 disk = get_gendisk(bdev->bd_dev, &partno);
795 if (!disk)
796 return ERR_PTR(-ENXIO);
797
798 /*
799 * Normally, @bdev should equal what's returned from bdget_disk()
800 * if partno is 0; however, some drivers (floppy) use multiple
801 * bdev's for the same physical device and @bdev may be one of the
802 * aliases. Keep @bdev if partno is 0. This means claimer
803 * tracking is broken for those devices but it has always been that
804 * way.
805 */
806 if (partno)
807 whole = bdget_disk(disk, 0);
808 else
809 whole = bdgrab(bdev);
810
811 module_put(disk->fops->owner);
812 put_disk(disk);
813 if (!whole)
814 return ERR_PTR(-ENOMEM);
815
816 /* prepare to claim, if successful, mark claiming in progress */
817 spin_lock(&bdev_lock);
818
819 err = bd_prepare_to_claim(bdev, whole, holder);
820 if (err == 0) {
821 whole->bd_claiming = holder;
822 spin_unlock(&bdev_lock);
823 return whole;
824 } else {
825 spin_unlock(&bdev_lock);
826 bdput(whole);
827 return ERR_PTR(err);
828 }
829}
830
831#ifdef CONFIG_SYSFS
832struct bd_holder_disk {
833 struct list_head list;
834 struct gendisk *disk;
835 int refcnt;
836};
837
838static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
839 struct gendisk *disk)
840{
841 struct bd_holder_disk *holder;
842
843 list_for_each_entry(holder, &bdev->bd_holder_disks, list)
844 if (holder->disk == disk)
845 return holder;
846 return NULL;
847}
848
849static int add_symlink(struct kobject *from, struct kobject *to)
850{
851 return sysfs_create_link(from, to, kobject_name(to));
852}
853
854static void del_symlink(struct kobject *from, struct kobject *to)
855{
856 sysfs_remove_link(from, kobject_name(to));
857}
858
859/**
860 * bd_link_disk_holder - create symlinks between holding disk and slave bdev
861 * @bdev: the claimed slave bdev
862 * @disk: the holding disk
863 *
864 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
865 *
866 * This functions creates the following sysfs symlinks.
867 *
868 * - from "slaves" directory of the holder @disk to the claimed @bdev
869 * - from "holders" directory of the @bdev to the holder @disk
870 *
871 * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
872 * passed to bd_link_disk_holder(), then:
873 *
874 * /sys/block/dm-0/slaves/sda --> /sys/block/sda
875 * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
876 *
877 * The caller must have claimed @bdev before calling this function and
878 * ensure that both @bdev and @disk are valid during the creation and
879 * lifetime of these symlinks.
880 *
881 * CONTEXT:
882 * Might sleep.
883 *
884 * RETURNS:
885 * 0 on success, -errno on failure.
886 */
887int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
888{
889 struct bd_holder_disk *holder;
890 int ret = 0;
891
892 mutex_lock(&bdev->bd_mutex);
893
894 WARN_ON_ONCE(!bdev->bd_holder);
895
896 /* FIXME: remove the following once add_disk() handles errors */
897 if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
898 goto out_unlock;
899
900 holder = bd_find_holder_disk(bdev, disk);
901 if (holder) {
902 holder->refcnt++;
903 goto out_unlock;
904 }
905
906 holder = kzalloc(sizeof(*holder), GFP_KERNEL);
907 if (!holder) {
908 ret = -ENOMEM;
909 goto out_unlock;
910 }
911
912 INIT_LIST_HEAD(&holder->list);
913 holder->disk = disk;
914 holder->refcnt = 1;
915
916 ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
917 if (ret)
918 goto out_free;
919
920 ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
921 if (ret)
922 goto out_del;
923 /*
924 * bdev could be deleted beneath us which would implicitly destroy
925 * the holder directory. Hold on to it.
926 */
927 kobject_get(bdev->bd_part->holder_dir);
928
929 list_add(&holder->list, &bdev->bd_holder_disks);
930 goto out_unlock;
931
932out_del:
933 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
934out_free:
935 kfree(holder);
936out_unlock:
937 mutex_unlock(&bdev->bd_mutex);
938 return ret;
939}
940EXPORT_SYMBOL_GPL(bd_link_disk_holder);
941
942/**
943 * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
944 * @bdev: the calimed slave bdev
945 * @disk: the holding disk
946 *
947 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
948 *
949 * CONTEXT:
950 * Might sleep.
951 */
952void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
953{
954 struct bd_holder_disk *holder;
955
956 mutex_lock(&bdev->bd_mutex);
957
958 holder = bd_find_holder_disk(bdev, disk);
959
960 if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
961 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
962 del_symlink(bdev->bd_part->holder_dir,
963 &disk_to_dev(disk)->kobj);
964 kobject_put(bdev->bd_part->holder_dir);
965 list_del_init(&holder->list);
966 kfree(holder);
967 }
968
969 mutex_unlock(&bdev->bd_mutex);
970}
971EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
972#endif
973
974/**
975 * flush_disk - invalidates all buffer-cache entries on a disk
976 *
977 * @bdev: struct block device to be flushed
978 * @kill_dirty: flag to guide handling of dirty inodes
979 *
980 * Invalidates all buffer-cache entries on a disk. It should be called
981 * when a disk has been changed -- either by a media change or online
982 * resize.
983 */
984static void flush_disk(struct block_device *bdev, bool kill_dirty)
985{
986 if (__invalidate_device(bdev, kill_dirty)) {
987 char name[BDEVNAME_SIZE] = "";
988
989 if (bdev->bd_disk)
990 disk_name(bdev->bd_disk, 0, name);
991 printk(KERN_WARNING "VFS: busy inodes on changed media or "
992 "resized disk %s\n", name);
993 }
994
995 if (!bdev->bd_disk)
996 return;
997 if (disk_part_scan_enabled(bdev->bd_disk))
998 bdev->bd_invalidated = 1;
999}
1000
1001/**
1002 * check_disk_size_change - checks for disk size change and adjusts bdev size.
1003 * @disk: struct gendisk to check
1004 * @bdev: struct bdev to adjust.
1005 *
1006 * This routine checks to see if the bdev size does not match the disk size
1007 * and adjusts it if it differs.
1008 */
1009void check_disk_size_change(struct gendisk *disk, struct block_device *bdev)
1010{
1011 loff_t disk_size, bdev_size;
1012
1013 disk_size = (loff_t)get_capacity(disk) << 9;
1014 bdev_size = i_size_read(bdev->bd_inode);
1015 if (disk_size != bdev_size) {
1016 char name[BDEVNAME_SIZE];
1017
1018 disk_name(disk, 0, name);
1019 printk(KERN_INFO
1020 "%s: detected capacity change from %lld to %lld\n",
1021 name, bdev_size, disk_size);
1022 i_size_write(bdev->bd_inode, disk_size);
1023 flush_disk(bdev, false);
1024 }
1025}
1026EXPORT_SYMBOL(check_disk_size_change);
1027
1028/**
1029 * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
1030 * @disk: struct gendisk to be revalidated
1031 *
1032 * This routine is a wrapper for lower-level driver's revalidate_disk
1033 * call-backs. It is used to do common pre and post operations needed
1034 * for all revalidate_disk operations.
1035 */
1036int revalidate_disk(struct gendisk *disk)
1037{
1038 struct block_device *bdev;
1039 int ret = 0;
1040
1041 if (disk->fops->revalidate_disk)
1042 ret = disk->fops->revalidate_disk(disk);
1043
1044 bdev = bdget_disk(disk, 0);
1045 if (!bdev)
1046 return ret;
1047
1048 mutex_lock(&bdev->bd_mutex);
1049 check_disk_size_change(disk, bdev);
1050 mutex_unlock(&bdev->bd_mutex);
1051 bdput(bdev);
1052 return ret;
1053}
1054EXPORT_SYMBOL(revalidate_disk);
1055
1056/*
1057 * This routine checks whether a removable media has been changed,
1058 * and invalidates all buffer-cache-entries in that case. This
1059 * is a relatively slow routine, so we have to try to minimize using
1060 * it. Thus it is called only upon a 'mount' or 'open'. This
1061 * is the best way of combining speed and utility, I think.
1062 * People changing diskettes in the middle of an operation deserve
1063 * to lose :-)
1064 */
1065int check_disk_change(struct block_device *bdev)
1066{
1067 struct gendisk *disk = bdev->bd_disk;
1068 const struct block_device_operations *bdops = disk->fops;
1069 unsigned int events;
1070
1071 events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
1072 DISK_EVENT_EJECT_REQUEST);
1073 if (!(events & DISK_EVENT_MEDIA_CHANGE))
1074 return 0;
1075
1076 flush_disk(bdev, true);
1077 if (bdops->revalidate_disk)
1078 bdops->revalidate_disk(bdev->bd_disk);
1079 return 1;
1080}
1081
1082EXPORT_SYMBOL(check_disk_change);
1083
1084void bd_set_size(struct block_device *bdev, loff_t size)
1085{
1086 unsigned bsize = bdev_logical_block_size(bdev);
1087
1088 bdev->bd_inode->i_size = size;
1089 while (bsize < PAGE_CACHE_SIZE) {
1090 if (size & bsize)
1091 break;
1092 bsize <<= 1;
1093 }
1094 bdev->bd_block_size = bsize;
1095 bdev->bd_inode->i_blkbits = blksize_bits(bsize);
1096}
1097EXPORT_SYMBOL(bd_set_size);
1098
1099static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
1100
1101/*
1102 * bd_mutex locking:
1103 *
1104 * mutex_lock(part->bd_mutex)
1105 * mutex_lock_nested(whole->bd_mutex, 1)
1106 */
1107
1108static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
1109{
1110 struct gendisk *disk;
1111 struct module *owner;
1112 int ret;
1113 int partno;
1114 int perm = 0;
1115
1116 if (mode & FMODE_READ)
1117 perm |= MAY_READ;
1118 if (mode & FMODE_WRITE)
1119 perm |= MAY_WRITE;
1120 /*
1121 * hooks: /n/, see "layering violations".
1122 */
1123 if (!for_part) {
1124 ret = devcgroup_inode_permission(bdev->bd_inode, perm);
1125 if (ret != 0) {
1126 bdput(bdev);
1127 return ret;
1128 }
1129 }
1130
1131 restart:
1132
1133 ret = -ENXIO;
1134 disk = get_gendisk(bdev->bd_dev, &partno);
1135 if (!disk)
1136 goto out;
1137 owner = disk->fops->owner;
1138
1139 disk_block_events(disk);
1140 mutex_lock_nested(&bdev->bd_mutex, for_part);
1141 if (!bdev->bd_openers) {
1142 bdev->bd_disk = disk;
1143 bdev->bd_queue = disk->queue;
1144 bdev->bd_contains = bdev;
1145 if (!partno) {
1146 struct backing_dev_info *bdi;
1147
1148 ret = -ENXIO;
1149 bdev->bd_part = disk_get_part(disk, partno);
1150 if (!bdev->bd_part)
1151 goto out_clear;
1152
1153 ret = 0;
1154 if (disk->fops->open) {
1155 ret = disk->fops->open(bdev, mode);
1156 if (ret == -ERESTARTSYS) {
1157 /* Lost a race with 'disk' being
1158 * deleted, try again.
1159 * See md.c
1160 */
1161 disk_put_part(bdev->bd_part);
1162 bdev->bd_part = NULL;
1163 bdev->bd_disk = NULL;
1164 bdev->bd_queue = NULL;
1165 mutex_unlock(&bdev->bd_mutex);
1166 disk_unblock_events(disk);
1167 put_disk(disk);
1168 module_put(owner);
1169 goto restart;
1170 }
1171 }
1172
1173 if (!ret && !bdev->bd_openers) {
1174 bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
1175 bdi = blk_get_backing_dev_info(bdev);
1176 if (bdi == NULL)
1177 bdi = &default_backing_dev_info;
1178 bdev_inode_switch_bdi(bdev->bd_inode, bdi);
1179 }
1180
1181 /*
1182 * If the device is invalidated, rescan partition
1183 * if open succeeded or failed with -ENOMEDIUM.
1184 * The latter is necessary to prevent ghost
1185 * partitions on a removed medium.
1186 */
1187 if (bdev->bd_invalidated) {
1188 if (!ret)
1189 rescan_partitions(disk, bdev);
1190 else if (ret == -ENOMEDIUM)
1191 invalidate_partitions(disk, bdev);
1192 }
1193 if (ret)
1194 goto out_clear;
1195 } else {
1196 struct block_device *whole;
1197 whole = bdget_disk(disk, 0);
1198 ret = -ENOMEM;
1199 if (!whole)
1200 goto out_clear;
1201 BUG_ON(for_part);
1202 ret = __blkdev_get(whole, mode, 1);
1203 if (ret)
1204 goto out_clear;
1205 bdev->bd_contains = whole;
1206 bdev_inode_switch_bdi(bdev->bd_inode,
1207 whole->bd_inode->i_data.backing_dev_info);
1208 bdev->bd_part = disk_get_part(disk, partno);
1209 if (!(disk->flags & GENHD_FL_UP) ||
1210 !bdev->bd_part || !bdev->bd_part->nr_sects) {
1211 ret = -ENXIO;
1212 goto out_clear;
1213 }
1214 bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
1215 }
1216 } else {
1217 if (bdev->bd_contains == bdev) {
1218 ret = 0;
1219 if (bdev->bd_disk->fops->open)
1220 ret = bdev->bd_disk->fops->open(bdev, mode);
1221 /* the same as first opener case, read comment there */
1222 if (bdev->bd_invalidated) {
1223 if (!ret)
1224 rescan_partitions(bdev->bd_disk, bdev);
1225 else if (ret == -ENOMEDIUM)
1226 invalidate_partitions(bdev->bd_disk, bdev);
1227 }
1228 if (ret)
1229 goto out_unlock_bdev;
1230 }
1231 /* only one opener holds refs to the module and disk */
1232 put_disk(disk);
1233 module_put(owner);
1234 }
1235 bdev->bd_openers++;
1236 if (for_part)
1237 bdev->bd_part_count++;
1238 mutex_unlock(&bdev->bd_mutex);
1239 disk_unblock_events(disk);
1240 return 0;
1241
1242 out_clear:
1243 disk_put_part(bdev->bd_part);
1244 bdev->bd_disk = NULL;
1245 bdev->bd_part = NULL;
1246 bdev->bd_queue = NULL;
1247 bdev_inode_switch_bdi(bdev->bd_inode, &default_backing_dev_info);
1248 if (bdev != bdev->bd_contains)
1249 __blkdev_put(bdev->bd_contains, mode, 1);
1250 bdev->bd_contains = NULL;
1251 out_unlock_bdev:
1252 mutex_unlock(&bdev->bd_mutex);
1253 disk_unblock_events(disk);
1254 put_disk(disk);
1255 module_put(owner);
1256 out:
1257 bdput(bdev);
1258
1259 return ret;
1260}
1261
1262/**
1263 * blkdev_get - open a block device
1264 * @bdev: block_device to open
1265 * @mode: FMODE_* mask
1266 * @holder: exclusive holder identifier
1267 *
1268 * Open @bdev with @mode. If @mode includes %FMODE_EXCL, @bdev is
1269 * open with exclusive access. Specifying %FMODE_EXCL with %NULL
1270 * @holder is invalid. Exclusive opens may nest for the same @holder.
1271 *
1272 * On success, the reference count of @bdev is unchanged. On failure,
1273 * @bdev is put.
1274 *
1275 * CONTEXT:
1276 * Might sleep.
1277 *
1278 * RETURNS:
1279 * 0 on success, -errno on failure.
1280 */
1281int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
1282{
1283 struct block_device *whole = NULL;
1284 int res;
1285
1286 WARN_ON_ONCE((mode & FMODE_EXCL) && !holder);
1287
1288 if ((mode & FMODE_EXCL) && holder) {
1289 whole = bd_start_claiming(bdev, holder);
1290 if (IS_ERR(whole)) {
1291 bdput(bdev);
1292 return PTR_ERR(whole);
1293 }
1294 }
1295
1296 res = __blkdev_get(bdev, mode, 0);
1297
1298 if (whole) {
1299 struct gendisk *disk = whole->bd_disk;
1300
1301 /* finish claiming */
1302 mutex_lock(&bdev->bd_mutex);
1303 spin_lock(&bdev_lock);
1304
1305 if (!res) {
1306 BUG_ON(!bd_may_claim(bdev, whole, holder));
1307 /*
1308 * Note that for a whole device bd_holders
1309 * will be incremented twice, and bd_holder
1310 * will be set to bd_may_claim before being
1311 * set to holder
1312 */
1313 whole->bd_holders++;
1314 whole->bd_holder = bd_may_claim;
1315 bdev->bd_holders++;
1316 bdev->bd_holder = holder;
1317 }
1318
1319 /* tell others that we're done */
1320 BUG_ON(whole->bd_claiming != holder);
1321 whole->bd_claiming = NULL;
1322 wake_up_bit(&whole->bd_claiming, 0);
1323
1324 spin_unlock(&bdev_lock);
1325
1326 /*
1327 * Block event polling for write claims if requested. Any
1328 * write holder makes the write_holder state stick until
1329 * all are released. This is good enough and tracking
1330 * individual writeable reference is too fragile given the
1331 * way @mode is used in blkdev_get/put().
1332 */
1333 if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder &&
1334 (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
1335 bdev->bd_write_holder = true;
1336 disk_block_events(disk);
1337 }
1338
1339 mutex_unlock(&bdev->bd_mutex);
1340 bdput(whole);
1341 }
1342
1343 return res;
1344}
1345EXPORT_SYMBOL(blkdev_get);
1346
1347/**
1348 * blkdev_get_by_path - open a block device by name
1349 * @path: path to the block device to open
1350 * @mode: FMODE_* mask
1351 * @holder: exclusive holder identifier
1352 *
1353 * Open the blockdevice described by the device file at @path. @mode
1354 * and @holder are identical to blkdev_get().
1355 *
1356 * On success, the returned block_device has reference count of one.
1357 *
1358 * CONTEXT:
1359 * Might sleep.
1360 *
1361 * RETURNS:
1362 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1363 */
1364struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
1365 void *holder)
1366{
1367 struct block_device *bdev;
1368 int err;
1369
1370 bdev = lookup_bdev(path);
1371 if (IS_ERR(bdev))
1372 return bdev;
1373
1374 err = blkdev_get(bdev, mode, holder);
1375 if (err)
1376 return ERR_PTR(err);
1377
1378 if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) {
1379 blkdev_put(bdev, mode);
1380 return ERR_PTR(-EACCES);
1381 }
1382
1383 return bdev;
1384}
1385EXPORT_SYMBOL(blkdev_get_by_path);
1386
1387/**
1388 * blkdev_get_by_dev - open a block device by device number
1389 * @dev: device number of block device to open
1390 * @mode: FMODE_* mask
1391 * @holder: exclusive holder identifier
1392 *
1393 * Open the blockdevice described by device number @dev. @mode and
1394 * @holder are identical to blkdev_get().
1395 *
1396 * Use it ONLY if you really do not have anything better - i.e. when
1397 * you are behind a truly sucky interface and all you are given is a
1398 * device number. _Never_ to be used for internal purposes. If you
1399 * ever need it - reconsider your API.
1400 *
1401 * On success, the returned block_device has reference count of one.
1402 *
1403 * CONTEXT:
1404 * Might sleep.
1405 *
1406 * RETURNS:
1407 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1408 */
1409struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
1410{
1411 struct block_device *bdev;
1412 int err;
1413
1414 bdev = bdget(dev);
1415 if (!bdev)
1416 return ERR_PTR(-ENOMEM);
1417
1418 err = blkdev_get(bdev, mode, holder);
1419 if (err)
1420 return ERR_PTR(err);
1421
1422 return bdev;
1423}
1424EXPORT_SYMBOL(blkdev_get_by_dev);
1425
1426static int blkdev_open(struct inode * inode, struct file * filp)
1427{
1428 struct block_device *bdev;
1429
1430 /*
1431 * Preserve backwards compatibility and allow large file access
1432 * even if userspace doesn't ask for it explicitly. Some mkfs
1433 * binary needs it. We might want to drop this workaround
1434 * during an unstable branch.
1435 */
1436 filp->f_flags |= O_LARGEFILE;
1437
1438 if (filp->f_flags & O_NDELAY)
1439 filp->f_mode |= FMODE_NDELAY;
1440 if (filp->f_flags & O_EXCL)
1441 filp->f_mode |= FMODE_EXCL;
1442 if ((filp->f_flags & O_ACCMODE) == 3)
1443 filp->f_mode |= FMODE_WRITE_IOCTL;
1444
1445 bdev = bd_acquire(inode);
1446 if (bdev == NULL)
1447 return -ENOMEM;
1448
1449 filp->f_mapping = bdev->bd_inode->i_mapping;
1450
1451 return blkdev_get(bdev, filp->f_mode, filp);
1452}
1453
1454static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
1455{
1456 int ret = 0;
1457 struct gendisk *disk = bdev->bd_disk;
1458 struct block_device *victim = NULL;
1459
1460 mutex_lock_nested(&bdev->bd_mutex, for_part);
1461 if (for_part)
1462 bdev->bd_part_count--;
1463
1464 if (!--bdev->bd_openers) {
1465 WARN_ON_ONCE(bdev->bd_holders);
1466 sync_blockdev(bdev);
1467 kill_bdev(bdev);
1468 /* ->release can cause the old bdi to disappear,
1469 * so must switch it out first
1470 */
1471 bdev_inode_switch_bdi(bdev->bd_inode,
1472 &default_backing_dev_info);
1473 }
1474 if (bdev->bd_contains == bdev) {
1475 if (disk->fops->release)
1476 ret = disk->fops->release(disk, mode);
1477 }
1478 if (!bdev->bd_openers) {
1479 struct module *owner = disk->fops->owner;
1480
1481 disk_put_part(bdev->bd_part);
1482 bdev->bd_part = NULL;
1483 bdev->bd_disk = NULL;
1484 if (bdev != bdev->bd_contains)
1485 victim = bdev->bd_contains;
1486 bdev->bd_contains = NULL;
1487
1488 put_disk(disk);
1489 module_put(owner);
1490 }
1491 mutex_unlock(&bdev->bd_mutex);
1492 bdput(bdev);
1493 if (victim)
1494 __blkdev_put(victim, mode, 1);
1495 return ret;
1496}
1497
1498int blkdev_put(struct block_device *bdev, fmode_t mode)
1499{
1500 mutex_lock(&bdev->bd_mutex);
1501
1502 if (mode & FMODE_EXCL) {
1503 bool bdev_free;
1504
1505 /*
1506 * Release a claim on the device. The holder fields
1507 * are protected with bdev_lock. bd_mutex is to
1508 * synchronize disk_holder unlinking.
1509 */
1510 spin_lock(&bdev_lock);
1511
1512 WARN_ON_ONCE(--bdev->bd_holders < 0);
1513 WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0);
1514
1515 /* bd_contains might point to self, check in a separate step */
1516 if ((bdev_free = !bdev->bd_holders))
1517 bdev->bd_holder = NULL;
1518 if (!bdev->bd_contains->bd_holders)
1519 bdev->bd_contains->bd_holder = NULL;
1520
1521 spin_unlock(&bdev_lock);
1522
1523 /*
1524 * If this was the last claim, remove holder link and
1525 * unblock evpoll if it was a write holder.
1526 */
1527 if (bdev_free && bdev->bd_write_holder) {
1528 disk_unblock_events(bdev->bd_disk);
1529 bdev->bd_write_holder = false;
1530 }
1531 }
1532
1533 /*
1534 * Trigger event checking and tell drivers to flush MEDIA_CHANGE
1535 * event. This is to ensure detection of media removal commanded
1536 * from userland - e.g. eject(1).
1537 */
1538 disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE);
1539
1540 mutex_unlock(&bdev->bd_mutex);
1541
1542 return __blkdev_put(bdev, mode, 0);
1543}
1544EXPORT_SYMBOL(blkdev_put);
1545
1546static int blkdev_close(struct inode * inode, struct file * filp)
1547{
1548 struct block_device *bdev = I_BDEV(filp->f_mapping->host);
1549
1550 return blkdev_put(bdev, filp->f_mode);
1551}
1552
1553static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
1554{
1555 struct block_device *bdev = I_BDEV(file->f_mapping->host);
1556 fmode_t mode = file->f_mode;
1557
1558 /*
1559 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
1560 * to updated it before every ioctl.
1561 */
1562 if (file->f_flags & O_NDELAY)
1563 mode |= FMODE_NDELAY;
1564 else
1565 mode &= ~FMODE_NDELAY;
1566
1567 return blkdev_ioctl(bdev, mode, cmd, arg);
1568}
1569
1570/*
1571 * Write data to the block device. Only intended for the block device itself
1572 * and the raw driver which basically is a fake block device.
1573 *
1574 * Does not take i_mutex for the write and thus is not for general purpose
1575 * use.
1576 */
1577ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
1578 unsigned long nr_segs, loff_t pos)
1579{
1580 struct file *file = iocb->ki_filp;
1581 ssize_t ret;
1582
1583 BUG_ON(iocb->ki_pos != pos);
1584
1585 ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
1586 if (ret > 0 || ret == -EIOCBQUEUED) {
1587 ssize_t err;
1588
1589 err = generic_write_sync(file, pos, ret);
1590 if (err < 0 && ret > 0)
1591 ret = err;
1592 }
1593 return ret;
1594}
1595EXPORT_SYMBOL_GPL(blkdev_aio_write);
1596
1597/*
1598 * Try to release a page associated with block device when the system
1599 * is under memory pressure.
1600 */
1601static int blkdev_releasepage(struct page *page, gfp_t wait)
1602{
1603 struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;
1604
1605 if (super && super->s_op->bdev_try_to_free_page)
1606 return super->s_op->bdev_try_to_free_page(super, page, wait);
1607
1608 return try_to_free_buffers(page);
1609}
1610
1611static const struct address_space_operations def_blk_aops = {
1612 .readpage = blkdev_readpage,
1613 .writepage = blkdev_writepage,
1614 .write_begin = blkdev_write_begin,
1615 .write_end = blkdev_write_end,
1616 .writepages = generic_writepages,
1617 .releasepage = blkdev_releasepage,
1618 .direct_IO = blkdev_direct_IO,
1619};
1620
1621const struct file_operations def_blk_fops = {
1622 .open = blkdev_open,
1623 .release = blkdev_close,
1624 .llseek = block_llseek,
1625 .read = do_sync_read,
1626 .write = do_sync_write,
1627 .aio_read = generic_file_aio_read,
1628 .aio_write = blkdev_aio_write,
1629 .mmap = generic_file_mmap,
1630 .fsync = blkdev_fsync,
1631 .unlocked_ioctl = block_ioctl,
1632#ifdef CONFIG_COMPAT
1633 .compat_ioctl = compat_blkdev_ioctl,
1634#endif
1635 .splice_read = generic_file_splice_read,
1636 .splice_write = generic_file_splice_write,
1637};
1638
1639int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
1640{
1641 int res;
1642 mm_segment_t old_fs = get_fs();
1643 set_fs(KERNEL_DS);
1644 res = blkdev_ioctl(bdev, 0, cmd, arg);
1645 set_fs(old_fs);
1646 return res;
1647}
1648
1649EXPORT_SYMBOL(ioctl_by_bdev);
1650
1651/**
1652 * lookup_bdev - lookup a struct block_device by name
1653 * @pathname: special file representing the block device
1654 *
1655 * Get a reference to the blockdevice at @pathname in the current
1656 * namespace if possible and return it. Return ERR_PTR(error)
1657 * otherwise.
1658 */
1659struct block_device *lookup_bdev(const char *pathname)
1660{
1661 struct block_device *bdev;
1662 struct inode *inode;
1663 struct path path;
1664 int error;
1665
1666 if (!pathname || !*pathname)
1667 return ERR_PTR(-EINVAL);
1668
1669 error = kern_path(pathname, LOOKUP_FOLLOW, &path);
1670 if (error)
1671 return ERR_PTR(error);
1672
1673 inode = path.dentry->d_inode;
1674 error = -ENOTBLK;
1675 if (!S_ISBLK(inode->i_mode))
1676 goto fail;
1677 error = -EACCES;
1678 if (path.mnt->mnt_flags & MNT_NODEV)
1679 goto fail;
1680 error = -ENOMEM;
1681 bdev = bd_acquire(inode);
1682 if (!bdev)
1683 goto fail;
1684out:
1685 path_put(&path);
1686 return bdev;
1687fail:
1688 bdev = ERR_PTR(error);
1689 goto out;
1690}
1691EXPORT_SYMBOL(lookup_bdev);
1692
1693int __invalidate_device(struct block_device *bdev, bool kill_dirty)
1694{
1695 struct super_block *sb = get_super(bdev);
1696 int res = 0;
1697
1698 if (sb) {
1699 /*
1700 * no need to lock the super, get_super holds the
1701 * read mutex so the filesystem cannot go away
1702 * under us (->put_super runs with the write lock
1703 * hold).
1704 */
1705 shrink_dcache_sb(sb);
1706 res = invalidate_inodes(sb, kill_dirty);
1707 drop_super(sb);
1708 }
1709 invalidate_bdev(bdev);
1710 return res;
1711}
1712EXPORT_SYMBOL(__invalidate_device);