projects/linux·blob v3.10 · refs

1715 lines · 42.0 KiB

1/*
2 * linux/fs/block_dev.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright (C) 2001 Andrea Arcangeli <[email protected]> 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 <linux/aio.h>
31#include <asm/uaccess.h>
32#include "internal.h"
33
34struct bdev_inode {
35 struct block_device bdev;
36 struct inode vfs_inode;
37};
38
39static const struct address_space_operations def_blk_aops;
40
41static inline struct bdev_inode *BDEV_I(struct inode *inode)
42{
43 return container_of(inode, struct bdev_inode, vfs_inode);
44}
45
46inline struct block_device *I_BDEV(struct inode *inode)
47{
48 return &BDEV_I(inode)->bdev;
49}
50EXPORT_SYMBOL(I_BDEV);
51
52/*
53 * Move the inode from its current bdi to a new bdi. If the inode is dirty we
54 * need to move it onto the dirty list of @dst so that the inode is always on
55 * the right list.
56 */
57static void bdev_inode_switch_bdi(struct inode *inode,
58 struct backing_dev_info *dst)
59{
60 struct backing_dev_info *old = inode->i_data.backing_dev_info;
61
62 if (unlikely(dst == old)) /* deadlock avoidance */
63 return;
64 bdi_lock_two(&old->wb, &dst->wb);
65 spin_lock(&inode->i_lock);
66 inode->i_data.backing_dev_info = dst;
67 if (inode->i_state & I_DIRTY)
68 list_move(&inode->i_wb_list, &dst->wb.b_dirty);
69 spin_unlock(&inode->i_lock);
70 spin_unlock(&old->wb.list_lock);
71 spin_unlock(&dst->wb.list_lock);
72}
73
74/* Kill _all_ buffers and pagecache , dirty or not.. */
75void kill_bdev(struct block_device *bdev)
76{
77 struct address_space *mapping = bdev->bd_inode->i_mapping;
78
79 if (mapping->nrpages == 0)
80 return;
81
82 invalidate_bh_lrus();
83 truncate_inode_pages(mapping, 0);
84}
85EXPORT_SYMBOL(kill_bdev);
86
87/* Invalidate clean unused buffers and pagecache. */
88void invalidate_bdev(struct block_device *bdev)
89{
90 struct address_space *mapping = bdev->bd_inode->i_mapping;
91
92 if (mapping->nrpages == 0)
93 return;
94
95 invalidate_bh_lrus();
96 lru_add_drain_all(); /* make sure all lru add caches are flushed */
97 invalidate_mapping_pages(mapping, 0, -1);
98 /* 99% of the time, we don't need to flush the cleancache on the bdev.
99 * But, for the strange corners, lets be cautious
100 */
101 cleancache_invalidate_inode(mapping);
102}
103EXPORT_SYMBOL(invalidate_bdev);
104
105int set_blocksize(struct block_device *bdev, int size)
106{
107 /* Size must be a power of two, and between 512 and PAGE_SIZE */
108 if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
109 return -EINVAL;
110
111 /* Size cannot be smaller than the size supported by the device */
112 if (size < bdev_logical_block_size(bdev))
113 return -EINVAL;
114
115 /* Don't change the size if it is same as current */
116 if (bdev->bd_block_size != size) {
117 sync_blockdev(bdev);
118 bdev->bd_block_size = size;
119 bdev->bd_inode->i_blkbits = blksize_bits(size);
120 kill_bdev(bdev);
121 }
122 return 0;
123}
124
125EXPORT_SYMBOL(set_blocksize);
126
127int sb_set_blocksize(struct super_block *sb, int size)
128{
129 if (set_blocksize(sb->s_bdev, size))
130 return 0;
131 /* If we get here, we know size is power of two
132 * and it's value is between 512 and PAGE_SIZE */
133 sb->s_blocksize = size;
134 sb->s_blocksize_bits = blksize_bits(size);
135 return sb->s_blocksize;
136}
137
138EXPORT_SYMBOL(sb_set_blocksize);
139
140int sb_min_blocksize(struct super_block *sb, int size)
141{
142 int minsize = bdev_logical_block_size(sb->s_bdev);
143 if (size < minsize)
144 size = minsize;
145 return sb_set_blocksize(sb, size);
146}
147
148EXPORT_SYMBOL(sb_min_blocksize);
149
150static int
151blkdev_get_block(struct inode *inode, sector_t iblock,
152 struct buffer_head *bh, int create)
153{
154 bh->b_bdev = I_BDEV(inode);
155 bh->b_blocknr = iblock;
156 set_buffer_mapped(bh);
157 return 0;
158}
159
160static ssize_t
161blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
162 loff_t offset, unsigned long nr_segs)
163{
164 struct file *file = iocb->ki_filp;
165 struct inode *inode = file->f_mapping->host;
166
167 return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset,
168 nr_segs, blkdev_get_block, NULL, NULL, 0);
169}
170
171int __sync_blockdev(struct block_device *bdev, int wait)
172{
173 if (!bdev)
174 return 0;
175 if (!wait)
176 return filemap_flush(bdev->bd_inode->i_mapping);
177 return filemap_write_and_wait(bdev->bd_inode->i_mapping);
178}
179
180/*
181 * Write out and wait upon all the dirty data associated with a block
182 * device via its mapping. Does not take the superblock lock.
183 */
184int sync_blockdev(struct block_device *bdev)
185{
186 return __sync_blockdev(bdev, 1);
187}
188EXPORT_SYMBOL(sync_blockdev);
189
190/*
191 * Write out and wait upon all dirty data associated with this
192 * device. Filesystem data as well as the underlying block
193 * device. Takes the superblock lock.
194 */
195int fsync_bdev(struct block_device *bdev)
196{
197 struct super_block *sb = get_super(bdev);
198 if (sb) {
199 int res = sync_filesystem(sb);
200 drop_super(sb);
201 return res;
202 }
203 return sync_blockdev(bdev);
204}
205EXPORT_SYMBOL(fsync_bdev);
206
207/**
208 * freeze_bdev -- lock a filesystem and force it into a consistent state
209 * @bdev: blockdevice to lock
210 *
211 * If a superblock is found on this device, we take the s_umount semaphore
212 * on it to make sure nobody unmounts until the snapshot creation is done.
213 * The reference counter (bd_fsfreeze_count) guarantees that only the last
214 * unfreeze process can unfreeze the frozen filesystem actually when multiple
215 * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
216 * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
217 * actually.
218 */
219struct super_block *freeze_bdev(struct block_device *bdev)
220{
221 struct super_block *sb;
222 int error = 0;
223
224 mutex_lock(&bdev->bd_fsfreeze_mutex);
225 if (++bdev->bd_fsfreeze_count > 1) {
226 /*
227 * We don't even need to grab a reference - the first call
228 * to freeze_bdev grab an active reference and only the last
229 * thaw_bdev drops it.
230 */
231 sb = get_super(bdev);
232 drop_super(sb);
233 mutex_unlock(&bdev->bd_fsfreeze_mutex);
234 return sb;
235 }
236
237 sb = get_active_super(bdev);
238 if (!sb)
239 goto out;
240 error = freeze_super(sb);
241 if (error) {
242 deactivate_super(sb);
243 bdev->bd_fsfreeze_count--;
244 mutex_unlock(&bdev->bd_fsfreeze_mutex);
245 return ERR_PTR(error);
246 }
247 deactivate_super(sb);
248 out:
249 sync_blockdev(bdev);
250 mutex_unlock(&bdev->bd_fsfreeze_mutex);
251 return sb; /* thaw_bdev releases s->s_umount */
252}
253EXPORT_SYMBOL(freeze_bdev);
254
255/**
256 * thaw_bdev -- unlock filesystem
257 * @bdev: blockdevice to unlock
258 * @sb: associated superblock
259 *
260 * Unlocks the filesystem and marks it writeable again after freeze_bdev().
261 */
262int thaw_bdev(struct block_device *bdev, struct super_block *sb)
263{
264 int error = -EINVAL;
265
266 mutex_lock(&bdev->bd_fsfreeze_mutex);
267 if (!bdev->bd_fsfreeze_count)
268 goto out;
269
270 error = 0;
271 if (--bdev->bd_fsfreeze_count > 0)
272 goto out;
273
274 if (!sb)
275 goto out;
276
277 error = thaw_super(sb);
278 if (error) {
279 bdev->bd_fsfreeze_count++;
280 mutex_unlock(&bdev->bd_fsfreeze_mutex);
281 return error;
282 }
283out:
284 mutex_unlock(&bdev->bd_fsfreeze_mutex);
285 return 0;
286}
287EXPORT_SYMBOL(thaw_bdev);
288
289static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
290{
291 return block_write_full_page(page, blkdev_get_block, wbc);
292}
293
294static int blkdev_readpage(struct file * file, struct page * page)
295{
296 return block_read_full_page(page, blkdev_get_block);
297}
298
299static int blkdev_write_begin(struct file *file, struct address_space *mapping,
300 loff_t pos, unsigned len, unsigned flags,
301 struct page **pagep, void **fsdata)
302{
303 return block_write_begin(mapping, pos, len, flags, pagep,
304 blkdev_get_block);
305}
306
307static int blkdev_write_end(struct file *file, struct address_space *mapping,
308 loff_t pos, unsigned len, unsigned copied,
309 struct page *page, void *fsdata)
310{
311 int ret;
312 ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
313
314 unlock_page(page);
315 page_cache_release(page);
316
317 return ret;
318}
319
320/*
321 * private llseek:
322 * for a block special file file_inode(file)->i_size is zero
323 * so we compute the size by hand (just as in block_read/write above)
324 */
325static loff_t block_llseek(struct file *file, loff_t offset, int whence)
326{
327 struct inode *bd_inode = file->f_mapping->host;
328 loff_t size;
329 loff_t retval;
330
331 mutex_lock(&bd_inode->i_mutex);
332 size = i_size_read(bd_inode);
333
334 retval = -EINVAL;
335 switch (whence) {
336 case SEEK_END:
337 offset += size;
338 break;
339 case SEEK_CUR:
340 offset += file->f_pos;
341 case SEEK_SET:
342 break;
343 default:
344 goto out;
345 }
346 if (offset >= 0 && offset <= size) {
347 if (offset != file->f_pos) {
348 file->f_pos = offset;
349 }
350 retval = offset;
351 }
352out:
353 mutex_unlock(&bd_inode->i_mutex);
354 return retval;
355}
356
357int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
358{
359 struct inode *bd_inode = filp->f_mapping->host;
360 struct block_device *bdev = I_BDEV(bd_inode);
361 int error;
362
363 error = filemap_write_and_wait_range(filp->f_mapping, start, end);
364 if (error)
365 return error;
366
367 /*
368 * There is no need to serialise calls to blkdev_issue_flush with
369 * i_mutex and doing so causes performance issues with concurrent
370 * O_SYNC writers to a block device.
371 */
372 error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL);
373 if (error == -EOPNOTSUPP)
374 error = 0;
375
376 return error;
377}
378EXPORT_SYMBOL(blkdev_fsync);
379
380/*
381 * pseudo-fs
382 */
383
384static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
385static struct kmem_cache * bdev_cachep __read_mostly;
386
387static struct inode *bdev_alloc_inode(struct super_block *sb)
388{
389 struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
390 if (!ei)
391 return NULL;
392 return &ei->vfs_inode;
393}
394
395static void bdev_i_callback(struct rcu_head *head)
396{
397 struct inode *inode = container_of(head, struct inode, i_rcu);
398 struct bdev_inode *bdi = BDEV_I(inode);
399
400 kmem_cache_free(bdev_cachep, bdi);
401}
402
403static void bdev_destroy_inode(struct inode *inode)
404{
405 call_rcu(&inode->i_rcu, bdev_i_callback);
406}
407
408static void init_once(void *foo)
409{
410 struct bdev_inode *ei = (struct bdev_inode *) foo;
411 struct block_device *bdev = &ei->bdev;
412
413 memset(bdev, 0, sizeof(*bdev));
414 mutex_init(&bdev->bd_mutex);
415 INIT_LIST_HEAD(&bdev->bd_inodes);
416 INIT_LIST_HEAD(&bdev->bd_list);
417#ifdef CONFIG_SYSFS
418 INIT_LIST_HEAD(&bdev->bd_holder_disks);
419#endif
420 inode_init_once(&ei->vfs_inode);
421 /* Initialize mutex for freeze. */
422 mutex_init(&bdev->bd_fsfreeze_mutex);
423}
424
425static inline void __bd_forget(struct inode *inode)
426{
427 list_del_init(&inode->i_devices);
428 inode->i_bdev = NULL;
429 inode->i_mapping = &inode->i_data;
430}
431
432static void bdev_evict_inode(struct inode *inode)
433{
434 struct block_device *bdev = &BDEV_I(inode)->bdev;
435 struct list_head *p;
436 truncate_inode_pages(&inode->i_data, 0);
437 invalidate_inode_buffers(inode); /* is it needed here? */
438 clear_inode(inode);
439 spin_lock(&bdev_lock);
440 while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) {
441 __bd_forget(list_entry(p, struct inode, i_devices));
442 }
443 list_del_init(&bdev->bd_list);
444 spin_unlock(&bdev_lock);
445}
446
447static const struct super_operations bdev_sops = {
448 .statfs = simple_statfs,
449 .alloc_inode = bdev_alloc_inode,
450 .destroy_inode = bdev_destroy_inode,
451 .drop_inode = generic_delete_inode,
452 .evict_inode = bdev_evict_inode,
453};
454
455static struct dentry *bd_mount(struct file_system_type *fs_type,
456 int flags, const char *dev_name, void *data)
457{
458 return mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC);
459}
460
461static struct file_system_type bd_type = {
462 .name = "bdev",
463 .mount = bd_mount,
464 .kill_sb = kill_anon_super,
465};
466
467static struct super_block *blockdev_superblock __read_mostly;
468
469void __init bdev_cache_init(void)
470{
471 int err;
472 static struct vfsmount *bd_mnt;
473
474 bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
475 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
476 SLAB_MEM_SPREAD|SLAB_PANIC),
477 init_once);
478 err = register_filesystem(&bd_type);
479 if (err)
480 panic("Cannot register bdev pseudo-fs");
481 bd_mnt = kern_mount(&bd_type);
482 if (IS_ERR(bd_mnt))
483 panic("Cannot create bdev pseudo-fs");
484 blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */
485}
486
487/*
488 * Most likely _very_ bad one - but then it's hardly critical for small
489 * /dev and can be fixed when somebody will need really large one.
490 * Keep in mind that it will be fed through icache hash function too.
491 */
492static inline unsigned long hash(dev_t dev)
493{
494 return MAJOR(dev)+MINOR(dev);
495}
496
497static int bdev_test(struct inode *inode, void *data)
498{
499 return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
500}
501
502static int bdev_set(struct inode *inode, void *data)
503{
504 BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
505 return 0;
506}
507
508static LIST_HEAD(all_bdevs);
509
510struct block_device *bdget(dev_t dev)
511{
512 struct block_device *bdev;
513 struct inode *inode;
514
515 inode = iget5_locked(blockdev_superblock, hash(dev),
516 bdev_test, bdev_set, &dev);
517
518 if (!inode)
519 return NULL;
520
521 bdev = &BDEV_I(inode)->bdev;
522
523 if (inode->i_state & I_NEW) {
524 bdev->bd_contains = NULL;
525 bdev->bd_super = NULL;
526 bdev->bd_inode = inode;
527 bdev->bd_block_size = (1 << inode->i_blkbits);
528 bdev->bd_part_count = 0;
529 bdev->bd_invalidated = 0;
530 inode->i_mode = S_IFBLK;
531 inode->i_rdev = dev;
532 inode->i_bdev = bdev;
533 inode->i_data.a_ops = &def_blk_aops;
534 mapping_set_gfp_mask(&inode->i_data, GFP_USER);
535 inode->i_data.backing_dev_info = &default_backing_dev_info;
536 spin_lock(&bdev_lock);
537 list_add(&bdev->bd_list, &all_bdevs);
538 spin_unlock(&bdev_lock);
539 unlock_new_inode(inode);
540 }
541 return bdev;
542}
543
544EXPORT_SYMBOL(bdget);
545
546/**
547 * bdgrab -- Grab a reference to an already referenced block device
548 * @bdev: Block device to grab a reference to.
549 */
550struct block_device *bdgrab(struct block_device *bdev)
551{
552 ihold(bdev->bd_inode);
553 return bdev;
554}
555EXPORT_SYMBOL(bdgrab);
556
557long nr_blockdev_pages(void)
558{
559 struct block_device *bdev;
560 long ret = 0;
561 spin_lock(&bdev_lock);
562 list_for_each_entry(bdev, &all_bdevs, bd_list) {
563 ret += bdev->bd_inode->i_mapping->nrpages;
564 }
565 spin_unlock(&bdev_lock);
566 return ret;
567}
568
569void bdput(struct block_device *bdev)
570{
571 iput(bdev->bd_inode);
572}
573
574EXPORT_SYMBOL(bdput);
575
576static struct block_device *bd_acquire(struct inode *inode)
577{
578 struct block_device *bdev;
579
580 spin_lock(&bdev_lock);
581 bdev = inode->i_bdev;
582 if (bdev) {
583 ihold(bdev->bd_inode);
584 spin_unlock(&bdev_lock);
585 return bdev;
586 }
587 spin_unlock(&bdev_lock);
588
589 bdev = bdget(inode->i_rdev);
590 if (bdev) {
591 spin_lock(&bdev_lock);
592 if (!inode->i_bdev) {
593 /*
594 * We take an additional reference to bd_inode,
595 * and it's released in clear_inode() of inode.
596 * So, we can access it via ->i_mapping always
597 * without igrab().
598 */
599 ihold(bdev->bd_inode);
600 inode->i_bdev = bdev;
601 inode->i_mapping = bdev->bd_inode->i_mapping;
602 list_add(&inode->i_devices, &bdev->bd_inodes);
603 }
604 spin_unlock(&bdev_lock);
605 }
606 return bdev;
607}
608
609static inline int sb_is_blkdev_sb(struct super_block *sb)
610{
611 return sb == blockdev_superblock;
612}
613
614/* Call when you free inode */
615
616void bd_forget(struct inode *inode)
617{
618 struct block_device *bdev = NULL;
619
620 spin_lock(&bdev_lock);
621 if (!sb_is_blkdev_sb(inode->i_sb))
622 bdev = inode->i_bdev;
623 __bd_forget(inode);
624 spin_unlock(&bdev_lock);
625
626 if (bdev)
627 iput(bdev->bd_inode);
628}
629
630/**
631 * bd_may_claim - test whether a block device can be claimed
632 * @bdev: block device of interest
633 * @whole: whole block device containing @bdev, may equal @bdev
634 * @holder: holder trying to claim @bdev
635 *
636 * Test whether @bdev can be claimed by @holder.
637 *
638 * CONTEXT:
639 * spin_lock(&bdev_lock).
640 *
641 * RETURNS:
642 * %true if @bdev can be claimed, %false otherwise.
643 */
644static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
645 void *holder)
646{
647 if (bdev->bd_holder == holder)
648 return true; /* already a holder */
649 else if (bdev->bd_holder != NULL)
650 return false; /* held by someone else */
651 else if (bdev->bd_contains == bdev)
652 return true; /* is a whole device which isn't held */
653
654 else if (whole->bd_holder == bd_may_claim)
655 return true; /* is a partition of a device that is being partitioned */
656 else if (whole->bd_holder != NULL)
657 return false; /* is a partition of a held device */
658 else
659 return true; /* is a partition of an un-held device */
660}
661
662/**
663 * bd_prepare_to_claim - prepare to claim a block device
664 * @bdev: block device of interest
665 * @whole: the whole device containing @bdev, may equal @bdev
666 * @holder: holder trying to claim @bdev
667 *
668 * Prepare to claim @bdev. This function fails if @bdev is already
669 * claimed by another holder and waits if another claiming is in
670 * progress. This function doesn't actually claim. On successful
671 * return, the caller has ownership of bd_claiming and bd_holder[s].
672 *
673 * CONTEXT:
674 * spin_lock(&bdev_lock). Might release bdev_lock, sleep and regrab
675 * it multiple times.
676 *
677 * RETURNS:
678 * 0 if @bdev can be claimed, -EBUSY otherwise.
679 */
680static int bd_prepare_to_claim(struct block_device *bdev,
681 struct block_device *whole, void *holder)
682{
683retry:
684 /* if someone else claimed, fail */
685 if (!bd_may_claim(bdev, whole, holder))
686 return -EBUSY;
687
688 /* if claiming is already in progress, wait for it to finish */
689 if (whole->bd_claiming) {
690 wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
691 DEFINE_WAIT(wait);
692
693 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
694 spin_unlock(&bdev_lock);
695 schedule();
696 finish_wait(wq, &wait);
697 spin_lock(&bdev_lock);
698 goto retry;
699 }
700
701 /* yay, all mine */
702 return 0;
703}
704
705/**
706 * bd_start_claiming - start claiming a block device
707 * @bdev: block device of interest
708 * @holder: holder trying to claim @bdev
709 *
710 * @bdev is about to be opened exclusively. Check @bdev can be opened
711 * exclusively and mark that an exclusive open is in progress. Each
712 * successful call to this function must be matched with a call to
713 * either bd_finish_claiming() or bd_abort_claiming() (which do not
714 * fail).
715 *
716 * This function is used to gain exclusive access to the block device
717 * without actually causing other exclusive open attempts to fail. It
718 * should be used when the open sequence itself requires exclusive
719 * access but may subsequently fail.
720 *
721 * CONTEXT:
722 * Might sleep.
723 *
724 * RETURNS:
725 * Pointer to the block device containing @bdev on success, ERR_PTR()
726 * value on failure.
727 */
728static struct block_device *bd_start_claiming(struct block_device *bdev,
729 void *holder)
730{
731 struct gendisk *disk;
732 struct block_device *whole;
733 int partno, err;
734
735 might_sleep();
736
737 /*
738 * @bdev might not have been initialized properly yet, look up
739 * and grab the outer block device the hard way.
740 */
741 disk = get_gendisk(bdev->bd_dev, &partno);
742 if (!disk)
743 return ERR_PTR(-ENXIO);
744
745 /*
746 * Normally, @bdev should equal what's returned from bdget_disk()
747 * if partno is 0; however, some drivers (floppy) use multiple
748 * bdev's for the same physical device and @bdev may be one of the
749 * aliases. Keep @bdev if partno is 0. This means claimer
750 * tracking is broken for those devices but it has always been that
751 * way.
752 */
753 if (partno)
754 whole = bdget_disk(disk, 0);
755 else
756 whole = bdgrab(bdev);
757
758 module_put(disk->fops->owner);
759 put_disk(disk);
760 if (!whole)
761 return ERR_PTR(-ENOMEM);
762
763 /* prepare to claim, if successful, mark claiming in progress */
764 spin_lock(&bdev_lock);
765
766 err = bd_prepare_to_claim(bdev, whole, holder);
767 if (err == 0) {
768 whole->bd_claiming = holder;
769 spin_unlock(&bdev_lock);
770 return whole;
771 } else {
772 spin_unlock(&bdev_lock);
773 bdput(whole);
774 return ERR_PTR(err);
775 }
776}
777
778#ifdef CONFIG_SYSFS
779struct bd_holder_disk {
780 struct list_head list;
781 struct gendisk *disk;
782 int refcnt;
783};
784
785static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
786 struct gendisk *disk)
787{
788 struct bd_holder_disk *holder;
789
790 list_for_each_entry(holder, &bdev->bd_holder_disks, list)
791 if (holder->disk == disk)
792 return holder;
793 return NULL;
794}
795
796static int add_symlink(struct kobject *from, struct kobject *to)
797{
798 return sysfs_create_link(from, to, kobject_name(to));
799}
800
801static void del_symlink(struct kobject *from, struct kobject *to)
802{
803 sysfs_remove_link(from, kobject_name(to));
804}
805
806/**
807 * bd_link_disk_holder - create symlinks between holding disk and slave bdev
808 * @bdev: the claimed slave bdev
809 * @disk: the holding disk
810 *
811 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
812 *
813 * This functions creates the following sysfs symlinks.
814 *
815 * - from "slaves" directory of the holder @disk to the claimed @bdev
816 * - from "holders" directory of the @bdev to the holder @disk
817 *
818 * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
819 * passed to bd_link_disk_holder(), then:
820 *
821 * /sys/block/dm-0/slaves/sda --> /sys/block/sda
822 * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
823 *
824 * The caller must have claimed @bdev before calling this function and
825 * ensure that both @bdev and @disk are valid during the creation and
826 * lifetime of these symlinks.
827 *
828 * CONTEXT:
829 * Might sleep.
830 *
831 * RETURNS:
832 * 0 on success, -errno on failure.
833 */
834int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
835{
836 struct bd_holder_disk *holder;
837 int ret = 0;
838
839 mutex_lock(&bdev->bd_mutex);
840
841 WARN_ON_ONCE(!bdev->bd_holder);
842
843 /* FIXME: remove the following once add_disk() handles errors */
844 if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
845 goto out_unlock;
846
847 holder = bd_find_holder_disk(bdev, disk);
848 if (holder) {
849 holder->refcnt++;
850 goto out_unlock;
851 }
852
853 holder = kzalloc(sizeof(*holder), GFP_KERNEL);
854 if (!holder) {
855 ret = -ENOMEM;
856 goto out_unlock;
857 }
858
859 INIT_LIST_HEAD(&holder->list);
860 holder->disk = disk;
861 holder->refcnt = 1;
862
863 ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
864 if (ret)
865 goto out_free;
866
867 ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
868 if (ret)
869 goto out_del;
870 /*
871 * bdev could be deleted beneath us which would implicitly destroy
872 * the holder directory. Hold on to it.
873 */
874 kobject_get(bdev->bd_part->holder_dir);
875
876 list_add(&holder->list, &bdev->bd_holder_disks);
877 goto out_unlock;
878
879out_del:
880 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
881out_free:
882 kfree(holder);
883out_unlock:
884 mutex_unlock(&bdev->bd_mutex);
885 return ret;
886}
887EXPORT_SYMBOL_GPL(bd_link_disk_holder);
888
889/**
890 * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
891 * @bdev: the calimed slave bdev
892 * @disk: the holding disk
893 *
894 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
895 *
896 * CONTEXT:
897 * Might sleep.
898 */
899void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
900{
901 struct bd_holder_disk *holder;
902
903 mutex_lock(&bdev->bd_mutex);
904
905 holder = bd_find_holder_disk(bdev, disk);
906
907 if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
908 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
909 del_symlink(bdev->bd_part->holder_dir,
910 &disk_to_dev(disk)->kobj);
911 kobject_put(bdev->bd_part->holder_dir);
912 list_del_init(&holder->list);
913 kfree(holder);
914 }
915
916 mutex_unlock(&bdev->bd_mutex);
917}
918EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
919#endif
920
921/**
922 * flush_disk - invalidates all buffer-cache entries on a disk
923 *
924 * @bdev: struct block device to be flushed
925 * @kill_dirty: flag to guide handling of dirty inodes
926 *
927 * Invalidates all buffer-cache entries on a disk. It should be called
928 * when a disk has been changed -- either by a media change or online
929 * resize.
930 */
931static void flush_disk(struct block_device *bdev, bool kill_dirty)
932{
933 if (__invalidate_device(bdev, kill_dirty)) {
934 char name[BDEVNAME_SIZE] = "";
935
936 if (bdev->bd_disk)
937 disk_name(bdev->bd_disk, 0, name);
938 printk(KERN_WARNING "VFS: busy inodes on changed media or "
939 "resized disk %s\n", name);
940 }
941
942 if (!bdev->bd_disk)
943 return;
944 if (disk_part_scan_enabled(bdev->bd_disk))
945 bdev->bd_invalidated = 1;
946}
947
948/**
949 * check_disk_size_change - checks for disk size change and adjusts bdev size.
950 * @disk: struct gendisk to check
951 * @bdev: struct bdev to adjust.
952 *
953 * This routine checks to see if the bdev size does not match the disk size
954 * and adjusts it if it differs.
955 */
956void check_disk_size_change(struct gendisk *disk, struct block_device *bdev)
957{
958 loff_t disk_size, bdev_size;
959
960 disk_size = (loff_t)get_capacity(disk) << 9;
961 bdev_size = i_size_read(bdev->bd_inode);
962 if (disk_size != bdev_size) {
963 char name[BDEVNAME_SIZE];
964
965 disk_name(disk, 0, name);
966 printk(KERN_INFO
967 "%s: detected capacity change from %lld to %lld\n",
968 name, bdev_size, disk_size);
969 i_size_write(bdev->bd_inode, disk_size);
970 flush_disk(bdev, false);
971 }
972}
973EXPORT_SYMBOL(check_disk_size_change);
974
975/**
976 * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
977 * @disk: struct gendisk to be revalidated
978 *
979 * This routine is a wrapper for lower-level driver's revalidate_disk
980 * call-backs. It is used to do common pre and post operations needed
981 * for all revalidate_disk operations.
982 */
983int revalidate_disk(struct gendisk *disk)
984{
985 struct block_device *bdev;
986 int ret = 0;
987
988 if (disk->fops->revalidate_disk)
989 ret = disk->fops->revalidate_disk(disk);
990
991 bdev = bdget_disk(disk, 0);
992 if (!bdev)
993 return ret;
994
995 mutex_lock(&bdev->bd_mutex);
996 check_disk_size_change(disk, bdev);
997 bdev->bd_invalidated = 0;
998 mutex_unlock(&bdev->bd_mutex);
999 bdput(bdev);
1000 return ret;
1001}
1002EXPORT_SYMBOL(revalidate_disk);
1003
1004/*
1005 * This routine checks whether a removable media has been changed,
1006 * and invalidates all buffer-cache-entries in that case. This
1007 * is a relatively slow routine, so we have to try to minimize using
1008 * it. Thus it is called only upon a 'mount' or 'open'. This
1009 * is the best way of combining speed and utility, I think.
1010 * People changing diskettes in the middle of an operation deserve
1011 * to lose :-)
1012 */
1013int check_disk_change(struct block_device *bdev)
1014{
1015 struct gendisk *disk = bdev->bd_disk;
1016 const struct block_device_operations *bdops = disk->fops;
1017 unsigned int events;
1018
1019 events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
1020 DISK_EVENT_EJECT_REQUEST);
1021 if (!(events & DISK_EVENT_MEDIA_CHANGE))
1022 return 0;
1023
1024 flush_disk(bdev, true);
1025 if (bdops->revalidate_disk)
1026 bdops->revalidate_disk(bdev->bd_disk);
1027 return 1;
1028}
1029
1030EXPORT_SYMBOL(check_disk_change);
1031
1032void bd_set_size(struct block_device *bdev, loff_t size)
1033{
1034 unsigned bsize = bdev_logical_block_size(bdev);
1035
1036 mutex_lock(&bdev->bd_inode->i_mutex);
1037 i_size_write(bdev->bd_inode, size);
1038 mutex_unlock(&bdev->bd_inode->i_mutex);
1039 while (bsize < PAGE_CACHE_SIZE) {
1040 if (size & bsize)
1041 break;
1042 bsize <<= 1;
1043 }
1044 bdev->bd_block_size = bsize;
1045 bdev->bd_inode->i_blkbits = blksize_bits(bsize);
1046}
1047EXPORT_SYMBOL(bd_set_size);
1048
1049static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
1050
1051/*
1052 * bd_mutex locking:
1053 *
1054 * mutex_lock(part->bd_mutex)
1055 * mutex_lock_nested(whole->bd_mutex, 1)
1056 */
1057
1058static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
1059{
1060 struct gendisk *disk;
1061 struct module *owner;
1062 int ret;
1063 int partno;
1064 int perm = 0;
1065
1066 if (mode & FMODE_READ)
1067 perm |= MAY_READ;
1068 if (mode & FMODE_WRITE)
1069 perm |= MAY_WRITE;
1070 /*
1071 * hooks: /n/, see "layering violations".
1072 */
1073 if (!for_part) {
1074 ret = devcgroup_inode_permission(bdev->bd_inode, perm);
1075 if (ret != 0) {
1076 bdput(bdev);
1077 return ret;
1078 }
1079 }
1080
1081 restart:
1082
1083 ret = -ENXIO;
1084 disk = get_gendisk(bdev->bd_dev, &partno);
1085 if (!disk)
1086 goto out;
1087 owner = disk->fops->owner;
1088
1089 disk_block_events(disk);
1090 mutex_lock_nested(&bdev->bd_mutex, for_part);
1091 if (!bdev->bd_openers) {
1092 bdev->bd_disk = disk;
1093 bdev->bd_queue = disk->queue;
1094 bdev->bd_contains = bdev;
1095 if (!partno) {
1096 struct backing_dev_info *bdi;
1097
1098 ret = -ENXIO;
1099 bdev->bd_part = disk_get_part(disk, partno);
1100 if (!bdev->bd_part)
1101 goto out_clear;
1102
1103 ret = 0;
1104 if (disk->fops->open) {
1105 ret = disk->fops->open(bdev, mode);
1106 if (ret == -ERESTARTSYS) {
1107 /* Lost a race with 'disk' being
1108 * deleted, try again.
1109 * See md.c
1110 */
1111 disk_put_part(bdev->bd_part);
1112 bdev->bd_part = NULL;
1113 bdev->bd_disk = NULL;
1114 bdev->bd_queue = NULL;
1115 mutex_unlock(&bdev->bd_mutex);
1116 disk_unblock_events(disk);
1117 put_disk(disk);
1118 module_put(owner);
1119 goto restart;
1120 }
1121 }
1122
1123 if (!ret) {
1124 bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
1125 bdi = blk_get_backing_dev_info(bdev);
1126 if (bdi == NULL)
1127 bdi = &default_backing_dev_info;
1128 bdev_inode_switch_bdi(bdev->bd_inode, bdi);
1129 }
1130
1131 /*
1132 * If the device is invalidated, rescan partition
1133 * if open succeeded or failed with -ENOMEDIUM.
1134 * The latter is necessary to prevent ghost
1135 * partitions on a removed medium.
1136 */
1137 if (bdev->bd_invalidated) {
1138 if (!ret)
1139 rescan_partitions(disk, bdev);
1140 else if (ret == -ENOMEDIUM)
1141 invalidate_partitions(disk, bdev);
1142 }
1143 if (ret)
1144 goto out_clear;
1145 } else {
1146 struct block_device *whole;
1147 whole = bdget_disk(disk, 0);
1148 ret = -ENOMEM;
1149 if (!whole)
1150 goto out_clear;
1151 BUG_ON(for_part);
1152 ret = __blkdev_get(whole, mode, 1);
1153 if (ret)
1154 goto out_clear;
1155 bdev->bd_contains = whole;
1156 bdev_inode_switch_bdi(bdev->bd_inode,
1157 whole->bd_inode->i_data.backing_dev_info);
1158 bdev->bd_part = disk_get_part(disk, partno);
1159 if (!(disk->flags & GENHD_FL_UP) ||
1160 !bdev->bd_part || !bdev->bd_part->nr_sects) {
1161 ret = -ENXIO;
1162 goto out_clear;
1163 }
1164 bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
1165 }
1166 } else {
1167 if (bdev->bd_contains == bdev) {
1168 ret = 0;
1169 if (bdev->bd_disk->fops->open)
1170 ret = bdev->bd_disk->fops->open(bdev, mode);
1171 /* the same as first opener case, read comment there */
1172 if (bdev->bd_invalidated) {
1173 if (!ret)
1174 rescan_partitions(bdev->bd_disk, bdev);
1175 else if (ret == -ENOMEDIUM)
1176 invalidate_partitions(bdev->bd_disk, bdev);
1177 }
1178 if (ret)
1179 goto out_unlock_bdev;
1180 }
1181 /* only one opener holds refs to the module and disk */
1182 put_disk(disk);
1183 module_put(owner);
1184 }
1185 bdev->bd_openers++;
1186 if (for_part)
1187 bdev->bd_part_count++;
1188 mutex_unlock(&bdev->bd_mutex);
1189 disk_unblock_events(disk);
1190 return 0;
1191
1192 out_clear:
1193 disk_put_part(bdev->bd_part);
1194 bdev->bd_disk = NULL;
1195 bdev->bd_part = NULL;
1196 bdev->bd_queue = NULL;
1197 bdev_inode_switch_bdi(bdev->bd_inode, &default_backing_dev_info);
1198 if (bdev != bdev->bd_contains)
1199 __blkdev_put(bdev->bd_contains, mode, 1);
1200 bdev->bd_contains = NULL;
1201 out_unlock_bdev:
1202 mutex_unlock(&bdev->bd_mutex);
1203 disk_unblock_events(disk);
1204 put_disk(disk);
1205 module_put(owner);
1206 out:
1207 bdput(bdev);
1208
1209 return ret;
1210}
1211
1212/**
1213 * blkdev_get - open a block device
1214 * @bdev: block_device to open
1215 * @mode: FMODE_* mask
1216 * @holder: exclusive holder identifier
1217 *
1218 * Open @bdev with @mode. If @mode includes %FMODE_EXCL, @bdev is
1219 * open with exclusive access. Specifying %FMODE_EXCL with %NULL
1220 * @holder is invalid. Exclusive opens may nest for the same @holder.
1221 *
1222 * On success, the reference count of @bdev is unchanged. On failure,
1223 * @bdev is put.
1224 *
1225 * CONTEXT:
1226 * Might sleep.
1227 *
1228 * RETURNS:
1229 * 0 on success, -errno on failure.
1230 */
1231int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
1232{
1233 struct block_device *whole = NULL;
1234 int res;
1235
1236 WARN_ON_ONCE((mode & FMODE_EXCL) && !holder);
1237
1238 if ((mode & FMODE_EXCL) && holder) {
1239 whole = bd_start_claiming(bdev, holder);
1240 if (IS_ERR(whole)) {
1241 bdput(bdev);
1242 return PTR_ERR(whole);
1243 }
1244 }
1245
1246 res = __blkdev_get(bdev, mode, 0);
1247
1248 if (whole) {
1249 struct gendisk *disk = whole->bd_disk;
1250
1251 /* finish claiming */
1252 mutex_lock(&bdev->bd_mutex);
1253 spin_lock(&bdev_lock);
1254
1255 if (!res) {
1256 BUG_ON(!bd_may_claim(bdev, whole, holder));
1257 /*
1258 * Note that for a whole device bd_holders
1259 * will be incremented twice, and bd_holder
1260 * will be set to bd_may_claim before being
1261 * set to holder
1262 */
1263 whole->bd_holders++;
1264 whole->bd_holder = bd_may_claim;
1265 bdev->bd_holders++;
1266 bdev->bd_holder = holder;
1267 }
1268
1269 /* tell others that we're done */
1270 BUG_ON(whole->bd_claiming != holder);
1271 whole->bd_claiming = NULL;
1272 wake_up_bit(&whole->bd_claiming, 0);
1273
1274 spin_unlock(&bdev_lock);
1275
1276 /*
1277 * Block event polling for write claims if requested. Any
1278 * write holder makes the write_holder state stick until
1279 * all are released. This is good enough and tracking
1280 * individual writeable reference is too fragile given the
1281 * way @mode is used in blkdev_get/put().
1282 */
1283 if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder &&
1284 (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
1285 bdev->bd_write_holder = true;
1286 disk_block_events(disk);
1287 }
1288
1289 mutex_unlock(&bdev->bd_mutex);
1290 bdput(whole);
1291 }
1292
1293 return res;
1294}
1295EXPORT_SYMBOL(blkdev_get);
1296
1297/**
1298 * blkdev_get_by_path - open a block device by name
1299 * @path: path to the block device to open
1300 * @mode: FMODE_* mask
1301 * @holder: exclusive holder identifier
1302 *
1303 * Open the blockdevice described by the device file at @path. @mode
1304 * and @holder are identical to blkdev_get().
1305 *
1306 * On success, the returned block_device has reference count of one.
1307 *
1308 * CONTEXT:
1309 * Might sleep.
1310 *
1311 * RETURNS:
1312 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1313 */
1314struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
1315 void *holder)
1316{
1317 struct block_device *bdev;
1318 int err;
1319
1320 bdev = lookup_bdev(path);
1321 if (IS_ERR(bdev))
1322 return bdev;
1323
1324 err = blkdev_get(bdev, mode, holder);
1325 if (err)
1326 return ERR_PTR(err);
1327
1328 if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) {
1329 blkdev_put(bdev, mode);
1330 return ERR_PTR(-EACCES);
1331 }
1332
1333 return bdev;
1334}
1335EXPORT_SYMBOL(blkdev_get_by_path);
1336
1337/**
1338 * blkdev_get_by_dev - open a block device by device number
1339 * @dev: device number of block device to open
1340 * @mode: FMODE_* mask
1341 * @holder: exclusive holder identifier
1342 *
1343 * Open the blockdevice described by device number @dev. @mode and
1344 * @holder are identical to blkdev_get().
1345 *
1346 * Use it ONLY if you really do not have anything better - i.e. when
1347 * you are behind a truly sucky interface and all you are given is a
1348 * device number. _Never_ to be used for internal purposes. If you
1349 * ever need it - reconsider your API.
1350 *
1351 * On success, the returned block_device has reference count of one.
1352 *
1353 * CONTEXT:
1354 * Might sleep.
1355 *
1356 * RETURNS:
1357 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1358 */
1359struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
1360{
1361 struct block_device *bdev;
1362 int err;
1363
1364 bdev = bdget(dev);
1365 if (!bdev)
1366 return ERR_PTR(-ENOMEM);
1367
1368 err = blkdev_get(bdev, mode, holder);
1369 if (err)
1370 return ERR_PTR(err);
1371
1372 return bdev;
1373}
1374EXPORT_SYMBOL(blkdev_get_by_dev);
1375
1376static int blkdev_open(struct inode * inode, struct file * filp)
1377{
1378 struct block_device *bdev;
1379
1380 /*
1381 * Preserve backwards compatibility and allow large file access
1382 * even if userspace doesn't ask for it explicitly. Some mkfs
1383 * binary needs it. We might want to drop this workaround
1384 * during an unstable branch.
1385 */
1386 filp->f_flags |= O_LARGEFILE;
1387
1388 if (filp->f_flags & O_NDELAY)
1389 filp->f_mode |= FMODE_NDELAY;
1390 if (filp->f_flags & O_EXCL)
1391 filp->f_mode |= FMODE_EXCL;
1392 if ((filp->f_flags & O_ACCMODE) == 3)
1393 filp->f_mode |= FMODE_WRITE_IOCTL;
1394
1395 bdev = bd_acquire(inode);
1396 if (bdev == NULL)
1397 return -ENOMEM;
1398
1399 filp->f_mapping = bdev->bd_inode->i_mapping;
1400
1401 return blkdev_get(bdev, filp->f_mode, filp);
1402}
1403
1404static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
1405{
1406 struct gendisk *disk = bdev->bd_disk;
1407 struct block_device *victim = NULL;
1408
1409 mutex_lock_nested(&bdev->bd_mutex, for_part);
1410 if (for_part)
1411 bdev->bd_part_count--;
1412
1413 if (!--bdev->bd_openers) {
1414 WARN_ON_ONCE(bdev->bd_holders);
1415 sync_blockdev(bdev);
1416 kill_bdev(bdev);
1417 /* ->release can cause the old bdi to disappear,
1418 * so must switch it out first
1419 */
1420 bdev_inode_switch_bdi(bdev->bd_inode,
1421 &default_backing_dev_info);
1422 }
1423 if (bdev->bd_contains == bdev) {
1424 if (disk->fops->release)
1425 disk->fops->release(disk, mode);
1426 }
1427 if (!bdev->bd_openers) {
1428 struct module *owner = disk->fops->owner;
1429
1430 disk_put_part(bdev->bd_part);
1431 bdev->bd_part = NULL;
1432 bdev->bd_disk = NULL;
1433 if (bdev != bdev->bd_contains)
1434 victim = bdev->bd_contains;
1435 bdev->bd_contains = NULL;
1436
1437 put_disk(disk);
1438 module_put(owner);
1439 }
1440 mutex_unlock(&bdev->bd_mutex);
1441 bdput(bdev);
1442 if (victim)
1443 __blkdev_put(victim, mode, 1);
1444}
1445
1446void blkdev_put(struct block_device *bdev, fmode_t mode)
1447{
1448 mutex_lock(&bdev->bd_mutex);
1449
1450 if (mode & FMODE_EXCL) {
1451 bool bdev_free;
1452
1453 /*
1454 * Release a claim on the device. The holder fields
1455 * are protected with bdev_lock. bd_mutex is to
1456 * synchronize disk_holder unlinking.
1457 */
1458 spin_lock(&bdev_lock);
1459
1460 WARN_ON_ONCE(--bdev->bd_holders < 0);
1461 WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0);
1462
1463 /* bd_contains might point to self, check in a separate step */
1464 if ((bdev_free = !bdev->bd_holders))
1465 bdev->bd_holder = NULL;
1466 if (!bdev->bd_contains->bd_holders)
1467 bdev->bd_contains->bd_holder = NULL;
1468
1469 spin_unlock(&bdev_lock);
1470
1471 /*
1472 * If this was the last claim, remove holder link and
1473 * unblock evpoll if it was a write holder.
1474 */
1475 if (bdev_free && bdev->bd_write_holder) {
1476 disk_unblock_events(bdev->bd_disk);
1477 bdev->bd_write_holder = false;
1478 }
1479 }
1480
1481 /*
1482 * Trigger event checking and tell drivers to flush MEDIA_CHANGE
1483 * event. This is to ensure detection of media removal commanded
1484 * from userland - e.g. eject(1).
1485 */
1486 disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE);
1487
1488 mutex_unlock(&bdev->bd_mutex);
1489
1490 __blkdev_put(bdev, mode, 0);
1491}
1492EXPORT_SYMBOL(blkdev_put);
1493
1494static int blkdev_close(struct inode * inode, struct file * filp)
1495{
1496 struct block_device *bdev = I_BDEV(filp->f_mapping->host);
1497 blkdev_put(bdev, filp->f_mode);
1498 return 0;
1499}
1500
1501static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
1502{
1503 struct block_device *bdev = I_BDEV(file->f_mapping->host);
1504 fmode_t mode = file->f_mode;
1505
1506 /*
1507 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
1508 * to updated it before every ioctl.
1509 */
1510 if (file->f_flags & O_NDELAY)
1511 mode |= FMODE_NDELAY;
1512 else
1513 mode &= ~FMODE_NDELAY;
1514
1515 return blkdev_ioctl(bdev, mode, cmd, arg);
1516}
1517
1518/*
1519 * Write data to the block device. Only intended for the block device itself
1520 * and the raw driver which basically is a fake block device.
1521 *
1522 * Does not take i_mutex for the write and thus is not for general purpose
1523 * use.
1524 */
1525ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
1526 unsigned long nr_segs, loff_t pos)
1527{
1528 struct file *file = iocb->ki_filp;
1529 struct blk_plug plug;
1530 ssize_t ret;
1531
1532 BUG_ON(iocb->ki_pos != pos);
1533
1534 blk_start_plug(&plug);
1535 ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
1536 if (ret > 0 || ret == -EIOCBQUEUED) {
1537 ssize_t err;
1538
1539 err = generic_write_sync(file, pos, ret);
1540 if (err < 0 && ret > 0)
1541 ret = err;
1542 }
1543 blk_finish_plug(&plug);
1544 return ret;
1545}
1546EXPORT_SYMBOL_GPL(blkdev_aio_write);
1547
1548static ssize_t blkdev_aio_read(struct kiocb *iocb, const struct iovec *iov,
1549 unsigned long nr_segs, loff_t pos)
1550{
1551 struct file *file = iocb->ki_filp;
1552 struct inode *bd_inode = file->f_mapping->host;
1553 loff_t size = i_size_read(bd_inode);
1554
1555 if (pos >= size)
1556 return 0;
1557
1558 size -= pos;
1559 if (size < iocb->ki_left)
1560 nr_segs = iov_shorten((struct iovec *)iov, nr_segs, size);
1561 return generic_file_aio_read(iocb, iov, nr_segs, pos);
1562}
1563
1564/*
1565 * Try to release a page associated with block device when the system
1566 * is under memory pressure.
1567 */
1568static int blkdev_releasepage(struct page *page, gfp_t wait)
1569{
1570 struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;
1571
1572 if (super && super->s_op->bdev_try_to_free_page)
1573 return super->s_op->bdev_try_to_free_page(super, page, wait);
1574
1575 return try_to_free_buffers(page);
1576}
1577
1578static const struct address_space_operations def_blk_aops = {
1579 .readpage = blkdev_readpage,
1580 .writepage = blkdev_writepage,
1581 .write_begin = blkdev_write_begin,
1582 .write_end = blkdev_write_end,
1583 .writepages = generic_writepages,
1584 .releasepage = blkdev_releasepage,
1585 .direct_IO = blkdev_direct_IO,
1586};
1587
1588const struct file_operations def_blk_fops = {
1589 .open = blkdev_open,
1590 .release = blkdev_close,
1591 .llseek = block_llseek,
1592 .read = do_sync_read,
1593 .write = do_sync_write,
1594 .aio_read = blkdev_aio_read,
1595 .aio_write = blkdev_aio_write,
1596 .mmap = generic_file_mmap,
1597 .fsync = blkdev_fsync,
1598 .unlocked_ioctl = block_ioctl,
1599#ifdef CONFIG_COMPAT
1600 .compat_ioctl = compat_blkdev_ioctl,
1601#endif
1602 .splice_read = generic_file_splice_read,
1603 .splice_write = generic_file_splice_write,
1604};
1605
1606int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
1607{
1608 int res;
1609 mm_segment_t old_fs = get_fs();
1610 set_fs(KERNEL_DS);
1611 res = blkdev_ioctl(bdev, 0, cmd, arg);
1612 set_fs(old_fs);
1613 return res;
1614}
1615
1616EXPORT_SYMBOL(ioctl_by_bdev);
1617
1618/**
1619 * lookup_bdev - lookup a struct block_device by name
1620 * @pathname: special file representing the block device
1621 *
1622 * Get a reference to the blockdevice at @pathname in the current
1623 * namespace if possible and return it. Return ERR_PTR(error)
1624 * otherwise.
1625 */
1626struct block_device *lookup_bdev(const char *pathname)
1627{
1628 struct block_device *bdev;
1629 struct inode *inode;
1630 struct path path;
1631 int error;
1632
1633 if (!pathname || !*pathname)
1634 return ERR_PTR(-EINVAL);
1635
1636 error = kern_path(pathname, LOOKUP_FOLLOW, &path);
1637 if (error)
1638 return ERR_PTR(error);
1639
1640 inode = path.dentry->d_inode;
1641 error = -ENOTBLK;
1642 if (!S_ISBLK(inode->i_mode))
1643 goto fail;
1644 error = -EACCES;
1645 if (path.mnt->mnt_flags & MNT_NODEV)
1646 goto fail;
1647 error = -ENOMEM;
1648 bdev = bd_acquire(inode);
1649 if (!bdev)
1650 goto fail;
1651out:
1652 path_put(&path);
1653 return bdev;
1654fail:
1655 bdev = ERR_PTR(error);
1656 goto out;
1657}
1658EXPORT_SYMBOL(lookup_bdev);
1659
1660int __invalidate_device(struct block_device *bdev, bool kill_dirty)
1661{
1662 struct super_block *sb = get_super(bdev);
1663 int res = 0;
1664
1665 if (sb) {
1666 /*
1667 * no need to lock the super, get_super holds the
1668 * read mutex so the filesystem cannot go away
1669 * under us (->put_super runs with the write lock
1670 * hold).
1671 */
1672 shrink_dcache_sb(sb);
1673 res = invalidate_inodes(sb, kill_dirty);
1674 drop_super(sb);
1675 }
1676 invalidate_bdev(bdev);
1677 return res;
1678}
1679EXPORT_SYMBOL(__invalidate_device);
1680
1681void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
1682{
1683 struct inode *inode, *old_inode = NULL;
1684
1685 spin_lock(&inode_sb_list_lock);
1686 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
1687 struct address_space *mapping = inode->i_mapping;
1688
1689 spin_lock(&inode->i_lock);
1690 if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
1691 mapping->nrpages == 0) {
1692 spin_unlock(&inode->i_lock);
1693 continue;
1694 }
1695 __iget(inode);
1696 spin_unlock(&inode->i_lock);
1697 spin_unlock(&inode_sb_list_lock);
1698 /*
1699 * We hold a reference to 'inode' so it couldn't have been
1700 * removed from s_inodes list while we dropped the
1701 * inode_sb_list_lock. We cannot iput the inode now as we can
1702 * be holding the last reference and we cannot iput it under
1703 * inode_sb_list_lock. So we keep the reference and iput it
1704 * later.
1705 */
1706 iput(old_inode);
1707 old_inode = inode;
1708
1709 func(I_BDEV(inode), arg);
1710
1711 spin_lock(&inode_sb_list_lock);
1712 }
1713 spin_unlock(&inode_sb_list_lock);
1714 iput(old_inode);
1715}