Merge branch 'drm-nouveau-fixes-3.9' of git://anongit.freedesktop.org/git/nouveau...
[linux-2.6/libata-dev.git] / fs / block_dev.c
blobaae187a7f94a661edb82189496242fdac4c33fcf
1 /*
2 * linux/fs/block_dev.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
6 */
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"
33 struct bdev_inode {
34 struct block_device bdev;
35 struct inode vfs_inode;
38 static const struct address_space_operations def_blk_aops;
40 static inline struct bdev_inode *BDEV_I(struct inode *inode)
42 return container_of(inode, struct bdev_inode, vfs_inode);
45 inline struct block_device *I_BDEV(struct inode *inode)
47 return &BDEV_I(inode)->bdev;
49 EXPORT_SYMBOL(I_BDEV);
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.
56 static void bdev_inode_switch_bdi(struct inode *inode,
57 struct backing_dev_info *dst)
59 struct backing_dev_info *old = inode->i_data.backing_dev_info;
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);
73 /* Kill _all_ buffers and pagecache , dirty or not.. */
74 void kill_bdev(struct block_device *bdev)
76 struct address_space *mapping = bdev->bd_inode->i_mapping;
78 if (mapping->nrpages == 0)
79 return;
81 invalidate_bh_lrus();
82 truncate_inode_pages(mapping, 0);
84 EXPORT_SYMBOL(kill_bdev);
86 /* Invalidate clean unused buffers and pagecache. */
87 void invalidate_bdev(struct block_device *bdev)
89 struct address_space *mapping = bdev->bd_inode->i_mapping;
91 if (mapping->nrpages == 0)
92 return;
94 invalidate_bh_lrus();
95 lru_add_drain_all(); /* make sure all lru add caches are flushed */
96 invalidate_mapping_pages(mapping, 0, -1);
97 /* 99% of the time, we don't need to flush the cleancache on the bdev.
98 * But, for the strange corners, lets be cautious
100 cleancache_invalidate_inode(mapping);
102 EXPORT_SYMBOL(invalidate_bdev);
104 int set_blocksize(struct block_device *bdev, int size)
106 /* Size must be a power of two, and between 512 and PAGE_SIZE */
107 if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
108 return -EINVAL;
110 /* Size cannot be smaller than the size supported by the device */
111 if (size < bdev_logical_block_size(bdev))
112 return -EINVAL;
114 /* Don't change the size if it is same as current */
115 if (bdev->bd_block_size != size) {
116 sync_blockdev(bdev);
117 bdev->bd_block_size = size;
118 bdev->bd_inode->i_blkbits = blksize_bits(size);
119 kill_bdev(bdev);
121 return 0;
124 EXPORT_SYMBOL(set_blocksize);
126 int sb_set_blocksize(struct super_block *sb, int size)
128 if (set_blocksize(sb->s_bdev, size))
129 return 0;
130 /* If we get here, we know size is power of two
131 * and it's value is between 512 and PAGE_SIZE */
132 sb->s_blocksize = size;
133 sb->s_blocksize_bits = blksize_bits(size);
134 return sb->s_blocksize;
137 EXPORT_SYMBOL(sb_set_blocksize);
139 int sb_min_blocksize(struct super_block *sb, int size)
141 int minsize = bdev_logical_block_size(sb->s_bdev);
142 if (size < minsize)
143 size = minsize;
144 return sb_set_blocksize(sb, size);
147 EXPORT_SYMBOL(sb_min_blocksize);
149 static int
150 blkdev_get_block(struct inode *inode, sector_t iblock,
151 struct buffer_head *bh, int create)
153 bh->b_bdev = I_BDEV(inode);
154 bh->b_blocknr = iblock;
155 set_buffer_mapped(bh);
156 return 0;
159 static ssize_t
160 blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
161 loff_t offset, unsigned long nr_segs)
163 struct file *file = iocb->ki_filp;
164 struct inode *inode = file->f_mapping->host;
166 return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset,
167 nr_segs, blkdev_get_block, NULL, NULL, 0);
170 int __sync_blockdev(struct block_device *bdev, int wait)
172 if (!bdev)
173 return 0;
174 if (!wait)
175 return filemap_flush(bdev->bd_inode->i_mapping);
176 return filemap_write_and_wait(bdev->bd_inode->i_mapping);
180 * Write out and wait upon all the dirty data associated with a block
181 * device via its mapping. Does not take the superblock lock.
183 int sync_blockdev(struct block_device *bdev)
185 return __sync_blockdev(bdev, 1);
187 EXPORT_SYMBOL(sync_blockdev);
190 * Write out and wait upon all dirty data associated with this
191 * device. Filesystem data as well as the underlying block
192 * device. Takes the superblock lock.
194 int fsync_bdev(struct block_device *bdev)
196 struct super_block *sb = get_super(bdev);
197 if (sb) {
198 int res = sync_filesystem(sb);
199 drop_super(sb);
200 return res;
202 return sync_blockdev(bdev);
204 EXPORT_SYMBOL(fsync_bdev);
207 * freeze_bdev -- lock a filesystem and force it into a consistent state
208 * @bdev: blockdevice to lock
210 * If a superblock is found on this device, we take the s_umount semaphore
211 * on it to make sure nobody unmounts until the snapshot creation is done.
212 * The reference counter (bd_fsfreeze_count) guarantees that only the last
213 * unfreeze process can unfreeze the frozen filesystem actually when multiple
214 * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
215 * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
216 * actually.
218 struct super_block *freeze_bdev(struct block_device *bdev)
220 struct super_block *sb;
221 int error = 0;
223 mutex_lock(&bdev->bd_fsfreeze_mutex);
224 if (++bdev->bd_fsfreeze_count > 1) {
226 * We don't even need to grab a reference - the first call
227 * to freeze_bdev grab an active reference and only the last
228 * thaw_bdev drops it.
230 sb = get_super(bdev);
231 drop_super(sb);
232 mutex_unlock(&bdev->bd_fsfreeze_mutex);
233 return sb;
236 sb = get_active_super(bdev);
237 if (!sb)
238 goto out;
239 error = freeze_super(sb);
240 if (error) {
241 deactivate_super(sb);
242 bdev->bd_fsfreeze_count--;
243 mutex_unlock(&bdev->bd_fsfreeze_mutex);
244 return ERR_PTR(error);
246 deactivate_super(sb);
247 out:
248 sync_blockdev(bdev);
249 mutex_unlock(&bdev->bd_fsfreeze_mutex);
250 return sb; /* thaw_bdev releases s->s_umount */
252 EXPORT_SYMBOL(freeze_bdev);
255 * thaw_bdev -- unlock filesystem
256 * @bdev: blockdevice to unlock
257 * @sb: associated superblock
259 * Unlocks the filesystem and marks it writeable again after freeze_bdev().
261 int thaw_bdev(struct block_device *bdev, struct super_block *sb)
263 int error = -EINVAL;
265 mutex_lock(&bdev->bd_fsfreeze_mutex);
266 if (!bdev->bd_fsfreeze_count)
267 goto out;
269 error = 0;
270 if (--bdev->bd_fsfreeze_count > 0)
271 goto out;
273 if (!sb)
274 goto out;
276 error = thaw_super(sb);
277 if (error) {
278 bdev->bd_fsfreeze_count++;
279 mutex_unlock(&bdev->bd_fsfreeze_mutex);
280 return error;
282 out:
283 mutex_unlock(&bdev->bd_fsfreeze_mutex);
284 return 0;
286 EXPORT_SYMBOL(thaw_bdev);
288 static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
290 return block_write_full_page(page, blkdev_get_block, wbc);
293 static int blkdev_readpage(struct file * file, struct page * page)
295 return block_read_full_page(page, blkdev_get_block);
298 static int blkdev_write_begin(struct file *file, struct address_space *mapping,
299 loff_t pos, unsigned len, unsigned flags,
300 struct page **pagep, void **fsdata)
302 return block_write_begin(mapping, pos, len, flags, pagep,
303 blkdev_get_block);
306 static int blkdev_write_end(struct file *file, struct address_space *mapping,
307 loff_t pos, unsigned len, unsigned copied,
308 struct page *page, void *fsdata)
310 int ret;
311 ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
313 unlock_page(page);
314 page_cache_release(page);
316 return ret;
320 * private llseek:
321 * for a block special file file_inode(file)->i_size is zero
322 * so we compute the size by hand (just as in block_read/write above)
324 static loff_t block_llseek(struct file *file, loff_t offset, int whence)
326 struct inode *bd_inode = file->f_mapping->host;
327 loff_t size;
328 loff_t retval;
330 mutex_lock(&bd_inode->i_mutex);
331 size = i_size_read(bd_inode);
333 retval = -EINVAL;
334 switch (whence) {
335 case SEEK_END:
336 offset += size;
337 break;
338 case SEEK_CUR:
339 offset += file->f_pos;
340 case SEEK_SET:
341 break;
342 default:
343 goto out;
345 if (offset >= 0 && offset <= size) {
346 if (offset != file->f_pos) {
347 file->f_pos = offset;
349 retval = offset;
351 out:
352 mutex_unlock(&bd_inode->i_mutex);
353 return retval;
356 int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
358 struct inode *bd_inode = filp->f_mapping->host;
359 struct block_device *bdev = I_BDEV(bd_inode);
360 int error;
362 error = filemap_write_and_wait_range(filp->f_mapping, start, end);
363 if (error)
364 return error;
367 * There is no need to serialise calls to blkdev_issue_flush with
368 * i_mutex and doing so causes performance issues with concurrent
369 * O_SYNC writers to a block device.
371 error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL);
372 if (error == -EOPNOTSUPP)
373 error = 0;
375 return error;
377 EXPORT_SYMBOL(blkdev_fsync);
380 * pseudo-fs
383 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
384 static struct kmem_cache * bdev_cachep __read_mostly;
386 static struct inode *bdev_alloc_inode(struct super_block *sb)
388 struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
389 if (!ei)
390 return NULL;
391 return &ei->vfs_inode;
394 static void bdev_i_callback(struct rcu_head *head)
396 struct inode *inode = container_of(head, struct inode, i_rcu);
397 struct bdev_inode *bdi = BDEV_I(inode);
399 kmem_cache_free(bdev_cachep, bdi);
402 static void bdev_destroy_inode(struct inode *inode)
404 call_rcu(&inode->i_rcu, bdev_i_callback);
407 static void init_once(void *foo)
409 struct bdev_inode *ei = (struct bdev_inode *) foo;
410 struct block_device *bdev = &ei->bdev;
412 memset(bdev, 0, sizeof(*bdev));
413 mutex_init(&bdev->bd_mutex);
414 INIT_LIST_HEAD(&bdev->bd_inodes);
415 INIT_LIST_HEAD(&bdev->bd_list);
416 #ifdef CONFIG_SYSFS
417 INIT_LIST_HEAD(&bdev->bd_holder_disks);
418 #endif
419 inode_init_once(&ei->vfs_inode);
420 /* Initialize mutex for freeze. */
421 mutex_init(&bdev->bd_fsfreeze_mutex);
424 static inline void __bd_forget(struct inode *inode)
426 list_del_init(&inode->i_devices);
427 inode->i_bdev = NULL;
428 inode->i_mapping = &inode->i_data;
431 static void bdev_evict_inode(struct inode *inode)
433 struct block_device *bdev = &BDEV_I(inode)->bdev;
434 struct list_head *p;
435 truncate_inode_pages(&inode->i_data, 0);
436 invalidate_inode_buffers(inode); /* is it needed here? */
437 clear_inode(inode);
438 spin_lock(&bdev_lock);
439 while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) {
440 __bd_forget(list_entry(p, struct inode, i_devices));
442 list_del_init(&bdev->bd_list);
443 spin_unlock(&bdev_lock);
446 static const struct super_operations bdev_sops = {
447 .statfs = simple_statfs,
448 .alloc_inode = bdev_alloc_inode,
449 .destroy_inode = bdev_destroy_inode,
450 .drop_inode = generic_delete_inode,
451 .evict_inode = bdev_evict_inode,
454 static struct dentry *bd_mount(struct file_system_type *fs_type,
455 int flags, const char *dev_name, void *data)
457 return mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC);
460 static struct file_system_type bd_type = {
461 .name = "bdev",
462 .mount = bd_mount,
463 .kill_sb = kill_anon_super,
466 static struct super_block *blockdev_superblock __read_mostly;
468 void __init bdev_cache_init(void)
470 int err;
471 static struct vfsmount *bd_mnt;
473 bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
474 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
475 SLAB_MEM_SPREAD|SLAB_PANIC),
476 init_once);
477 err = register_filesystem(&bd_type);
478 if (err)
479 panic("Cannot register bdev pseudo-fs");
480 bd_mnt = kern_mount(&bd_type);
481 if (IS_ERR(bd_mnt))
482 panic("Cannot create bdev pseudo-fs");
483 blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */
487 * Most likely _very_ bad one - but then it's hardly critical for small
488 * /dev and can be fixed when somebody will need really large one.
489 * Keep in mind that it will be fed through icache hash function too.
491 static inline unsigned long hash(dev_t dev)
493 return MAJOR(dev)+MINOR(dev);
496 static int bdev_test(struct inode *inode, void *data)
498 return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
501 static int bdev_set(struct inode *inode, void *data)
503 BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
504 return 0;
507 static LIST_HEAD(all_bdevs);
509 struct block_device *bdget(dev_t dev)
511 struct block_device *bdev;
512 struct inode *inode;
514 inode = iget5_locked(blockdev_superblock, hash(dev),
515 bdev_test, bdev_set, &dev);
517 if (!inode)
518 return NULL;
520 bdev = &BDEV_I(inode)->bdev;
522 if (inode->i_state & I_NEW) {
523 bdev->bd_contains = NULL;
524 bdev->bd_super = NULL;
525 bdev->bd_inode = inode;
526 bdev->bd_block_size = (1 << inode->i_blkbits);
527 bdev->bd_part_count = 0;
528 bdev->bd_invalidated = 0;
529 inode->i_mode = S_IFBLK;
530 inode->i_rdev = dev;
531 inode->i_bdev = bdev;
532 inode->i_data.a_ops = &def_blk_aops;
533 mapping_set_gfp_mask(&inode->i_data, GFP_USER);
534 inode->i_data.backing_dev_info = &default_backing_dev_info;
535 spin_lock(&bdev_lock);
536 list_add(&bdev->bd_list, &all_bdevs);
537 spin_unlock(&bdev_lock);
538 unlock_new_inode(inode);
540 return bdev;
543 EXPORT_SYMBOL(bdget);
546 * bdgrab -- Grab a reference to an already referenced block device
547 * @bdev: Block device to grab a reference to.
549 struct block_device *bdgrab(struct block_device *bdev)
551 ihold(bdev->bd_inode);
552 return bdev;
554 EXPORT_SYMBOL(bdgrab);
556 long nr_blockdev_pages(void)
558 struct block_device *bdev;
559 long ret = 0;
560 spin_lock(&bdev_lock);
561 list_for_each_entry(bdev, &all_bdevs, bd_list) {
562 ret += bdev->bd_inode->i_mapping->nrpages;
564 spin_unlock(&bdev_lock);
565 return ret;
568 void bdput(struct block_device *bdev)
570 iput(bdev->bd_inode);
573 EXPORT_SYMBOL(bdput);
575 static struct block_device *bd_acquire(struct inode *inode)
577 struct block_device *bdev;
579 spin_lock(&bdev_lock);
580 bdev = inode->i_bdev;
581 if (bdev) {
582 ihold(bdev->bd_inode);
583 spin_unlock(&bdev_lock);
584 return bdev;
586 spin_unlock(&bdev_lock);
588 bdev = bdget(inode->i_rdev);
589 if (bdev) {
590 spin_lock(&bdev_lock);
591 if (!inode->i_bdev) {
593 * We take an additional reference to bd_inode,
594 * and it's released in clear_inode() of inode.
595 * So, we can access it via ->i_mapping always
596 * without igrab().
598 ihold(bdev->bd_inode);
599 inode->i_bdev = bdev;
600 inode->i_mapping = bdev->bd_inode->i_mapping;
601 list_add(&inode->i_devices, &bdev->bd_inodes);
603 spin_unlock(&bdev_lock);
605 return bdev;
608 static inline int sb_is_blkdev_sb(struct super_block *sb)
610 return sb == blockdev_superblock;
613 /* Call when you free inode */
615 void bd_forget(struct inode *inode)
617 struct block_device *bdev = NULL;
619 spin_lock(&bdev_lock);
620 if (inode->i_bdev) {
621 if (!sb_is_blkdev_sb(inode->i_sb))
622 bdev = inode->i_bdev;
623 __bd_forget(inode);
625 spin_unlock(&bdev_lock);
627 if (bdev)
628 iput(bdev->bd_inode);
632 * bd_may_claim - test whether a block device can be claimed
633 * @bdev: block device of interest
634 * @whole: whole block device containing @bdev, may equal @bdev
635 * @holder: holder trying to claim @bdev
637 * Test whether @bdev can be claimed by @holder.
639 * CONTEXT:
640 * spin_lock(&bdev_lock).
642 * RETURNS:
643 * %true if @bdev can be claimed, %false otherwise.
645 static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
646 void *holder)
648 if (bdev->bd_holder == holder)
649 return true; /* already a holder */
650 else if (bdev->bd_holder != NULL)
651 return false; /* held by someone else */
652 else if (bdev->bd_contains == bdev)
653 return true; /* is a whole device which isn't held */
655 else if (whole->bd_holder == bd_may_claim)
656 return true; /* is a partition of a device that is being partitioned */
657 else if (whole->bd_holder != NULL)
658 return false; /* is a partition of a held device */
659 else
660 return true; /* is a partition of an un-held device */
664 * bd_prepare_to_claim - prepare to claim a block device
665 * @bdev: block device of interest
666 * @whole: the whole device containing @bdev, may equal @bdev
667 * @holder: holder trying to claim @bdev
669 * Prepare to claim @bdev. This function fails if @bdev is already
670 * claimed by another holder and waits if another claiming is in
671 * progress. This function doesn't actually claim. On successful
672 * return, the caller has ownership of bd_claiming and bd_holder[s].
674 * CONTEXT:
675 * spin_lock(&bdev_lock). Might release bdev_lock, sleep and regrab
676 * it multiple times.
678 * RETURNS:
679 * 0 if @bdev can be claimed, -EBUSY otherwise.
681 static int bd_prepare_to_claim(struct block_device *bdev,
682 struct block_device *whole, void *holder)
684 retry:
685 /* if someone else claimed, fail */
686 if (!bd_may_claim(bdev, whole, holder))
687 return -EBUSY;
689 /* if claiming is already in progress, wait for it to finish */
690 if (whole->bd_claiming) {
691 wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
692 DEFINE_WAIT(wait);
694 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
695 spin_unlock(&bdev_lock);
696 schedule();
697 finish_wait(wq, &wait);
698 spin_lock(&bdev_lock);
699 goto retry;
702 /* yay, all mine */
703 return 0;
707 * bd_start_claiming - start claiming a block device
708 * @bdev: block device of interest
709 * @holder: holder trying to claim @bdev
711 * @bdev is about to be opened exclusively. Check @bdev can be opened
712 * exclusively and mark that an exclusive open is in progress. Each
713 * successful call to this function must be matched with a call to
714 * either bd_finish_claiming() or bd_abort_claiming() (which do not
715 * fail).
717 * This function is used to gain exclusive access to the block device
718 * without actually causing other exclusive open attempts to fail. It
719 * should be used when the open sequence itself requires exclusive
720 * access but may subsequently fail.
722 * CONTEXT:
723 * Might sleep.
725 * RETURNS:
726 * Pointer to the block device containing @bdev on success, ERR_PTR()
727 * value on failure.
729 static struct block_device *bd_start_claiming(struct block_device *bdev,
730 void *holder)
732 struct gendisk *disk;
733 struct block_device *whole;
734 int partno, err;
736 might_sleep();
739 * @bdev might not have been initialized properly yet, look up
740 * and grab the outer block device the hard way.
742 disk = get_gendisk(bdev->bd_dev, &partno);
743 if (!disk)
744 return ERR_PTR(-ENXIO);
747 * Normally, @bdev should equal what's returned from bdget_disk()
748 * if partno is 0; however, some drivers (floppy) use multiple
749 * bdev's for the same physical device and @bdev may be one of the
750 * aliases. Keep @bdev if partno is 0. This means claimer
751 * tracking is broken for those devices but it has always been that
752 * way.
754 if (partno)
755 whole = bdget_disk(disk, 0);
756 else
757 whole = bdgrab(bdev);
759 module_put(disk->fops->owner);
760 put_disk(disk);
761 if (!whole)
762 return ERR_PTR(-ENOMEM);
764 /* prepare to claim, if successful, mark claiming in progress */
765 spin_lock(&bdev_lock);
767 err = bd_prepare_to_claim(bdev, whole, holder);
768 if (err == 0) {
769 whole->bd_claiming = holder;
770 spin_unlock(&bdev_lock);
771 return whole;
772 } else {
773 spin_unlock(&bdev_lock);
774 bdput(whole);
775 return ERR_PTR(err);
779 #ifdef CONFIG_SYSFS
780 struct bd_holder_disk {
781 struct list_head list;
782 struct gendisk *disk;
783 int refcnt;
786 static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
787 struct gendisk *disk)
789 struct bd_holder_disk *holder;
791 list_for_each_entry(holder, &bdev->bd_holder_disks, list)
792 if (holder->disk == disk)
793 return holder;
794 return NULL;
797 static int add_symlink(struct kobject *from, struct kobject *to)
799 return sysfs_create_link(from, to, kobject_name(to));
802 static void del_symlink(struct kobject *from, struct kobject *to)
804 sysfs_remove_link(from, kobject_name(to));
808 * bd_link_disk_holder - create symlinks between holding disk and slave bdev
809 * @bdev: the claimed slave bdev
810 * @disk: the holding disk
812 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
814 * This functions creates the following sysfs symlinks.
816 * - from "slaves" directory of the holder @disk to the claimed @bdev
817 * - from "holders" directory of the @bdev to the holder @disk
819 * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
820 * passed to bd_link_disk_holder(), then:
822 * /sys/block/dm-0/slaves/sda --> /sys/block/sda
823 * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
825 * The caller must have claimed @bdev before calling this function and
826 * ensure that both @bdev and @disk are valid during the creation and
827 * lifetime of these symlinks.
829 * CONTEXT:
830 * Might sleep.
832 * RETURNS:
833 * 0 on success, -errno on failure.
835 int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
837 struct bd_holder_disk *holder;
838 int ret = 0;
840 mutex_lock(&bdev->bd_mutex);
842 WARN_ON_ONCE(!bdev->bd_holder);
844 /* FIXME: remove the following once add_disk() handles errors */
845 if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
846 goto out_unlock;
848 holder = bd_find_holder_disk(bdev, disk);
849 if (holder) {
850 holder->refcnt++;
851 goto out_unlock;
854 holder = kzalloc(sizeof(*holder), GFP_KERNEL);
855 if (!holder) {
856 ret = -ENOMEM;
857 goto out_unlock;
860 INIT_LIST_HEAD(&holder->list);
861 holder->disk = disk;
862 holder->refcnt = 1;
864 ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
865 if (ret)
866 goto out_free;
868 ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
869 if (ret)
870 goto out_del;
872 * bdev could be deleted beneath us which would implicitly destroy
873 * the holder directory. Hold on to it.
875 kobject_get(bdev->bd_part->holder_dir);
877 list_add(&holder->list, &bdev->bd_holder_disks);
878 goto out_unlock;
880 out_del:
881 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
882 out_free:
883 kfree(holder);
884 out_unlock:
885 mutex_unlock(&bdev->bd_mutex);
886 return ret;
888 EXPORT_SYMBOL_GPL(bd_link_disk_holder);
891 * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
892 * @bdev: the calimed slave bdev
893 * @disk: the holding disk
895 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
897 * CONTEXT:
898 * Might sleep.
900 void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
902 struct bd_holder_disk *holder;
904 mutex_lock(&bdev->bd_mutex);
906 holder = bd_find_holder_disk(bdev, disk);
908 if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
909 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
910 del_symlink(bdev->bd_part->holder_dir,
911 &disk_to_dev(disk)->kobj);
912 kobject_put(bdev->bd_part->holder_dir);
913 list_del_init(&holder->list);
914 kfree(holder);
917 mutex_unlock(&bdev->bd_mutex);
919 EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
920 #endif
923 * flush_disk - invalidates all buffer-cache entries on a disk
925 * @bdev: struct block device to be flushed
926 * @kill_dirty: flag to guide handling of dirty inodes
928 * Invalidates all buffer-cache entries on a disk. It should be called
929 * when a disk has been changed -- either by a media change or online
930 * resize.
932 static void flush_disk(struct block_device *bdev, bool kill_dirty)
934 if (__invalidate_device(bdev, kill_dirty)) {
935 char name[BDEVNAME_SIZE] = "";
937 if (bdev->bd_disk)
938 disk_name(bdev->bd_disk, 0, name);
939 printk(KERN_WARNING "VFS: busy inodes on changed media or "
940 "resized disk %s\n", name);
943 if (!bdev->bd_disk)
944 return;
945 if (disk_part_scan_enabled(bdev->bd_disk))
946 bdev->bd_invalidated = 1;
950 * check_disk_size_change - checks for disk size change and adjusts bdev size.
951 * @disk: struct gendisk to check
952 * @bdev: struct bdev to adjust.
954 * This routine checks to see if the bdev size does not match the disk size
955 * and adjusts it if it differs.
957 void check_disk_size_change(struct gendisk *disk, struct block_device *bdev)
959 loff_t disk_size, bdev_size;
961 disk_size = (loff_t)get_capacity(disk) << 9;
962 bdev_size = i_size_read(bdev->bd_inode);
963 if (disk_size != bdev_size) {
964 char name[BDEVNAME_SIZE];
966 disk_name(disk, 0, name);
967 printk(KERN_INFO
968 "%s: detected capacity change from %lld to %lld\n",
969 name, bdev_size, disk_size);
970 i_size_write(bdev->bd_inode, disk_size);
971 flush_disk(bdev, false);
974 EXPORT_SYMBOL(check_disk_size_change);
977 * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
978 * @disk: struct gendisk to be revalidated
980 * This routine is a wrapper for lower-level driver's revalidate_disk
981 * call-backs. It is used to do common pre and post operations needed
982 * for all revalidate_disk operations.
984 int revalidate_disk(struct gendisk *disk)
986 struct block_device *bdev;
987 int ret = 0;
989 if (disk->fops->revalidate_disk)
990 ret = disk->fops->revalidate_disk(disk);
992 bdev = bdget_disk(disk, 0);
993 if (!bdev)
994 return ret;
996 mutex_lock(&bdev->bd_mutex);
997 check_disk_size_change(disk, bdev);
998 bdev->bd_invalidated = 0;
999 mutex_unlock(&bdev->bd_mutex);
1000 bdput(bdev);
1001 return ret;
1003 EXPORT_SYMBOL(revalidate_disk);
1006 * This routine checks whether a removable media has been changed,
1007 * and invalidates all buffer-cache-entries in that case. This
1008 * is a relatively slow routine, so we have to try to minimize using
1009 * it. Thus it is called only upon a 'mount' or 'open'. This
1010 * is the best way of combining speed and utility, I think.
1011 * People changing diskettes in the middle of an operation deserve
1012 * to lose :-)
1014 int check_disk_change(struct block_device *bdev)
1016 struct gendisk *disk = bdev->bd_disk;
1017 const struct block_device_operations *bdops = disk->fops;
1018 unsigned int events;
1020 events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
1021 DISK_EVENT_EJECT_REQUEST);
1022 if (!(events & DISK_EVENT_MEDIA_CHANGE))
1023 return 0;
1025 flush_disk(bdev, true);
1026 if (bdops->revalidate_disk)
1027 bdops->revalidate_disk(bdev->bd_disk);
1028 return 1;
1031 EXPORT_SYMBOL(check_disk_change);
1033 void bd_set_size(struct block_device *bdev, loff_t size)
1035 unsigned bsize = bdev_logical_block_size(bdev);
1037 mutex_lock(&bdev->bd_inode->i_mutex);
1038 i_size_write(bdev->bd_inode, size);
1039 mutex_unlock(&bdev->bd_inode->i_mutex);
1040 while (bsize < PAGE_CACHE_SIZE) {
1041 if (size & bsize)
1042 break;
1043 bsize <<= 1;
1045 bdev->bd_block_size = bsize;
1046 bdev->bd_inode->i_blkbits = blksize_bits(bsize);
1048 EXPORT_SYMBOL(bd_set_size);
1050 static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
1053 * bd_mutex locking:
1055 * mutex_lock(part->bd_mutex)
1056 * mutex_lock_nested(whole->bd_mutex, 1)
1059 static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
1061 struct gendisk *disk;
1062 struct module *owner;
1063 int ret;
1064 int partno;
1065 int perm = 0;
1067 if (mode & FMODE_READ)
1068 perm |= MAY_READ;
1069 if (mode & FMODE_WRITE)
1070 perm |= MAY_WRITE;
1072 * hooks: /n/, see "layering violations".
1074 if (!for_part) {
1075 ret = devcgroup_inode_permission(bdev->bd_inode, perm);
1076 if (ret != 0) {
1077 bdput(bdev);
1078 return ret;
1082 restart:
1084 ret = -ENXIO;
1085 disk = get_gendisk(bdev->bd_dev, &partno);
1086 if (!disk)
1087 goto out;
1088 owner = disk->fops->owner;
1090 disk_block_events(disk);
1091 mutex_lock_nested(&bdev->bd_mutex, for_part);
1092 if (!bdev->bd_openers) {
1093 bdev->bd_disk = disk;
1094 bdev->bd_queue = disk->queue;
1095 bdev->bd_contains = bdev;
1096 if (!partno) {
1097 struct backing_dev_info *bdi;
1099 ret = -ENXIO;
1100 bdev->bd_part = disk_get_part(disk, partno);
1101 if (!bdev->bd_part)
1102 goto out_clear;
1104 ret = 0;
1105 if (disk->fops->open) {
1106 ret = disk->fops->open(bdev, mode);
1107 if (ret == -ERESTARTSYS) {
1108 /* Lost a race with 'disk' being
1109 * deleted, try again.
1110 * See md.c
1112 disk_put_part(bdev->bd_part);
1113 bdev->bd_part = NULL;
1114 bdev->bd_disk = NULL;
1115 bdev->bd_queue = NULL;
1116 mutex_unlock(&bdev->bd_mutex);
1117 disk_unblock_events(disk);
1118 put_disk(disk);
1119 module_put(owner);
1120 goto restart;
1124 if (!ret) {
1125 bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
1126 bdi = blk_get_backing_dev_info(bdev);
1127 if (bdi == NULL)
1128 bdi = &default_backing_dev_info;
1129 bdev_inode_switch_bdi(bdev->bd_inode, bdi);
1133 * If the device is invalidated, rescan partition
1134 * if open succeeded or failed with -ENOMEDIUM.
1135 * The latter is necessary to prevent ghost
1136 * partitions on a removed medium.
1138 if (bdev->bd_invalidated) {
1139 if (!ret)
1140 rescan_partitions(disk, bdev);
1141 else if (ret == -ENOMEDIUM)
1142 invalidate_partitions(disk, bdev);
1144 if (ret)
1145 goto out_clear;
1146 } else {
1147 struct block_device *whole;
1148 whole = bdget_disk(disk, 0);
1149 ret = -ENOMEM;
1150 if (!whole)
1151 goto out_clear;
1152 BUG_ON(for_part);
1153 ret = __blkdev_get(whole, mode, 1);
1154 if (ret)
1155 goto out_clear;
1156 bdev->bd_contains = whole;
1157 bdev_inode_switch_bdi(bdev->bd_inode,
1158 whole->bd_inode->i_data.backing_dev_info);
1159 bdev->bd_part = disk_get_part(disk, partno);
1160 if (!(disk->flags & GENHD_FL_UP) ||
1161 !bdev->bd_part || !bdev->bd_part->nr_sects) {
1162 ret = -ENXIO;
1163 goto out_clear;
1165 bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
1167 } else {
1168 if (bdev->bd_contains == bdev) {
1169 ret = 0;
1170 if (bdev->bd_disk->fops->open)
1171 ret = bdev->bd_disk->fops->open(bdev, mode);
1172 /* the same as first opener case, read comment there */
1173 if (bdev->bd_invalidated) {
1174 if (!ret)
1175 rescan_partitions(bdev->bd_disk, bdev);
1176 else if (ret == -ENOMEDIUM)
1177 invalidate_partitions(bdev->bd_disk, bdev);
1179 if (ret)
1180 goto out_unlock_bdev;
1182 /* only one opener holds refs to the module and disk */
1183 put_disk(disk);
1184 module_put(owner);
1186 bdev->bd_openers++;
1187 if (for_part)
1188 bdev->bd_part_count++;
1189 mutex_unlock(&bdev->bd_mutex);
1190 disk_unblock_events(disk);
1191 return 0;
1193 out_clear:
1194 disk_put_part(bdev->bd_part);
1195 bdev->bd_disk = NULL;
1196 bdev->bd_part = NULL;
1197 bdev->bd_queue = NULL;
1198 bdev_inode_switch_bdi(bdev->bd_inode, &default_backing_dev_info);
1199 if (bdev != bdev->bd_contains)
1200 __blkdev_put(bdev->bd_contains, mode, 1);
1201 bdev->bd_contains = NULL;
1202 out_unlock_bdev:
1203 mutex_unlock(&bdev->bd_mutex);
1204 disk_unblock_events(disk);
1205 put_disk(disk);
1206 module_put(owner);
1207 out:
1208 bdput(bdev);
1210 return ret;
1214 * blkdev_get - open a block device
1215 * @bdev: block_device to open
1216 * @mode: FMODE_* mask
1217 * @holder: exclusive holder identifier
1219 * Open @bdev with @mode. If @mode includes %FMODE_EXCL, @bdev is
1220 * open with exclusive access. Specifying %FMODE_EXCL with %NULL
1221 * @holder is invalid. Exclusive opens may nest for the same @holder.
1223 * On success, the reference count of @bdev is unchanged. On failure,
1224 * @bdev is put.
1226 * CONTEXT:
1227 * Might sleep.
1229 * RETURNS:
1230 * 0 on success, -errno on failure.
1232 int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
1234 struct block_device *whole = NULL;
1235 int res;
1237 WARN_ON_ONCE((mode & FMODE_EXCL) && !holder);
1239 if ((mode & FMODE_EXCL) && holder) {
1240 whole = bd_start_claiming(bdev, holder);
1241 if (IS_ERR(whole)) {
1242 bdput(bdev);
1243 return PTR_ERR(whole);
1247 res = __blkdev_get(bdev, mode, 0);
1249 if (whole) {
1250 struct gendisk *disk = whole->bd_disk;
1252 /* finish claiming */
1253 mutex_lock(&bdev->bd_mutex);
1254 spin_lock(&bdev_lock);
1256 if (!res) {
1257 BUG_ON(!bd_may_claim(bdev, whole, holder));
1259 * Note that for a whole device bd_holders
1260 * will be incremented twice, and bd_holder
1261 * will be set to bd_may_claim before being
1262 * set to holder
1264 whole->bd_holders++;
1265 whole->bd_holder = bd_may_claim;
1266 bdev->bd_holders++;
1267 bdev->bd_holder = holder;
1270 /* tell others that we're done */
1271 BUG_ON(whole->bd_claiming != holder);
1272 whole->bd_claiming = NULL;
1273 wake_up_bit(&whole->bd_claiming, 0);
1275 spin_unlock(&bdev_lock);
1278 * Block event polling for write claims if requested. Any
1279 * write holder makes the write_holder state stick until
1280 * all are released. This is good enough and tracking
1281 * individual writeable reference is too fragile given the
1282 * way @mode is used in blkdev_get/put().
1284 if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder &&
1285 (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
1286 bdev->bd_write_holder = true;
1287 disk_block_events(disk);
1290 mutex_unlock(&bdev->bd_mutex);
1291 bdput(whole);
1294 return res;
1296 EXPORT_SYMBOL(blkdev_get);
1299 * blkdev_get_by_path - open a block device by name
1300 * @path: path to the block device to open
1301 * @mode: FMODE_* mask
1302 * @holder: exclusive holder identifier
1304 * Open the blockdevice described by the device file at @path. @mode
1305 * and @holder are identical to blkdev_get().
1307 * On success, the returned block_device has reference count of one.
1309 * CONTEXT:
1310 * Might sleep.
1312 * RETURNS:
1313 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1315 struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
1316 void *holder)
1318 struct block_device *bdev;
1319 int err;
1321 bdev = lookup_bdev(path);
1322 if (IS_ERR(bdev))
1323 return bdev;
1325 err = blkdev_get(bdev, mode, holder);
1326 if (err)
1327 return ERR_PTR(err);
1329 if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) {
1330 blkdev_put(bdev, mode);
1331 return ERR_PTR(-EACCES);
1334 return bdev;
1336 EXPORT_SYMBOL(blkdev_get_by_path);
1339 * blkdev_get_by_dev - open a block device by device number
1340 * @dev: device number of block device to open
1341 * @mode: FMODE_* mask
1342 * @holder: exclusive holder identifier
1344 * Open the blockdevice described by device number @dev. @mode and
1345 * @holder are identical to blkdev_get().
1347 * Use it ONLY if you really do not have anything better - i.e. when
1348 * you are behind a truly sucky interface and all you are given is a
1349 * device number. _Never_ to be used for internal purposes. If you
1350 * ever need it - reconsider your API.
1352 * On success, the returned block_device has reference count of one.
1354 * CONTEXT:
1355 * Might sleep.
1357 * RETURNS:
1358 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1360 struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
1362 struct block_device *bdev;
1363 int err;
1365 bdev = bdget(dev);
1366 if (!bdev)
1367 return ERR_PTR(-ENOMEM);
1369 err = blkdev_get(bdev, mode, holder);
1370 if (err)
1371 return ERR_PTR(err);
1373 return bdev;
1375 EXPORT_SYMBOL(blkdev_get_by_dev);
1377 static int blkdev_open(struct inode * inode, struct file * filp)
1379 struct block_device *bdev;
1382 * Preserve backwards compatibility and allow large file access
1383 * even if userspace doesn't ask for it explicitly. Some mkfs
1384 * binary needs it. We might want to drop this workaround
1385 * during an unstable branch.
1387 filp->f_flags |= O_LARGEFILE;
1389 if (filp->f_flags & O_NDELAY)
1390 filp->f_mode |= FMODE_NDELAY;
1391 if (filp->f_flags & O_EXCL)
1392 filp->f_mode |= FMODE_EXCL;
1393 if ((filp->f_flags & O_ACCMODE) == 3)
1394 filp->f_mode |= FMODE_WRITE_IOCTL;
1396 bdev = bd_acquire(inode);
1397 if (bdev == NULL)
1398 return -ENOMEM;
1400 filp->f_mapping = bdev->bd_inode->i_mapping;
1402 return blkdev_get(bdev, filp->f_mode, filp);
1405 static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
1407 int ret = 0;
1408 struct gendisk *disk = bdev->bd_disk;
1409 struct block_device *victim = NULL;
1411 mutex_lock_nested(&bdev->bd_mutex, for_part);
1412 if (for_part)
1413 bdev->bd_part_count--;
1415 if (!--bdev->bd_openers) {
1416 WARN_ON_ONCE(bdev->bd_holders);
1417 sync_blockdev(bdev);
1418 kill_bdev(bdev);
1419 /* ->release can cause the old bdi to disappear,
1420 * so must switch it out first
1422 bdev_inode_switch_bdi(bdev->bd_inode,
1423 &default_backing_dev_info);
1425 if (bdev->bd_contains == bdev) {
1426 if (disk->fops->release)
1427 ret = disk->fops->release(disk, mode);
1429 if (!bdev->bd_openers) {
1430 struct module *owner = disk->fops->owner;
1432 disk_put_part(bdev->bd_part);
1433 bdev->bd_part = NULL;
1434 bdev->bd_disk = NULL;
1435 if (bdev != bdev->bd_contains)
1436 victim = bdev->bd_contains;
1437 bdev->bd_contains = NULL;
1439 put_disk(disk);
1440 module_put(owner);
1442 mutex_unlock(&bdev->bd_mutex);
1443 bdput(bdev);
1444 if (victim)
1445 __blkdev_put(victim, mode, 1);
1446 return ret;
1449 int blkdev_put(struct block_device *bdev, fmode_t mode)
1451 mutex_lock(&bdev->bd_mutex);
1453 if (mode & FMODE_EXCL) {
1454 bool bdev_free;
1457 * Release a claim on the device. The holder fields
1458 * are protected with bdev_lock. bd_mutex is to
1459 * synchronize disk_holder unlinking.
1461 spin_lock(&bdev_lock);
1463 WARN_ON_ONCE(--bdev->bd_holders < 0);
1464 WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0);
1466 /* bd_contains might point to self, check in a separate step */
1467 if ((bdev_free = !bdev->bd_holders))
1468 bdev->bd_holder = NULL;
1469 if (!bdev->bd_contains->bd_holders)
1470 bdev->bd_contains->bd_holder = NULL;
1472 spin_unlock(&bdev_lock);
1475 * If this was the last claim, remove holder link and
1476 * unblock evpoll if it was a write holder.
1478 if (bdev_free && bdev->bd_write_holder) {
1479 disk_unblock_events(bdev->bd_disk);
1480 bdev->bd_write_holder = false;
1485 * Trigger event checking and tell drivers to flush MEDIA_CHANGE
1486 * event. This is to ensure detection of media removal commanded
1487 * from userland - e.g. eject(1).
1489 disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE);
1491 mutex_unlock(&bdev->bd_mutex);
1493 return __blkdev_put(bdev, mode, 0);
1495 EXPORT_SYMBOL(blkdev_put);
1497 static int blkdev_close(struct inode * inode, struct file * filp)
1499 struct block_device *bdev = I_BDEV(filp->f_mapping->host);
1501 return blkdev_put(bdev, filp->f_mode);
1504 static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
1506 struct block_device *bdev = I_BDEV(file->f_mapping->host);
1507 fmode_t mode = file->f_mode;
1510 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
1511 * to updated it before every ioctl.
1513 if (file->f_flags & O_NDELAY)
1514 mode |= FMODE_NDELAY;
1515 else
1516 mode &= ~FMODE_NDELAY;
1518 return blkdev_ioctl(bdev, mode, cmd, arg);
1522 * Write data to the block device. Only intended for the block device itself
1523 * and the raw driver which basically is a fake block device.
1525 * Does not take i_mutex for the write and thus is not for general purpose
1526 * use.
1528 ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
1529 unsigned long nr_segs, loff_t pos)
1531 struct file *file = iocb->ki_filp;
1532 struct blk_plug plug;
1533 ssize_t ret;
1535 BUG_ON(iocb->ki_pos != pos);
1537 blk_start_plug(&plug);
1538 ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
1539 if (ret > 0 || ret == -EIOCBQUEUED) {
1540 ssize_t err;
1542 err = generic_write_sync(file, pos, ret);
1543 if (err < 0 && ret > 0)
1544 ret = err;
1546 blk_finish_plug(&plug);
1547 return ret;
1549 EXPORT_SYMBOL_GPL(blkdev_aio_write);
1551 static ssize_t blkdev_aio_read(struct kiocb *iocb, const struct iovec *iov,
1552 unsigned long nr_segs, loff_t pos)
1554 struct file *file = iocb->ki_filp;
1555 struct inode *bd_inode = file->f_mapping->host;
1556 loff_t size = i_size_read(bd_inode);
1558 if (pos >= size)
1559 return 0;
1561 size -= pos;
1562 if (size < INT_MAX)
1563 nr_segs = iov_shorten((struct iovec *)iov, nr_segs, size);
1564 return generic_file_aio_read(iocb, iov, nr_segs, pos);
1568 * Try to release a page associated with block device when the system
1569 * is under memory pressure.
1571 static int blkdev_releasepage(struct page *page, gfp_t wait)
1573 struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;
1575 if (super && super->s_op->bdev_try_to_free_page)
1576 return super->s_op->bdev_try_to_free_page(super, page, wait);
1578 return try_to_free_buffers(page);
1581 static const struct address_space_operations def_blk_aops = {
1582 .readpage = blkdev_readpage,
1583 .writepage = blkdev_writepage,
1584 .write_begin = blkdev_write_begin,
1585 .write_end = blkdev_write_end,
1586 .writepages = generic_writepages,
1587 .releasepage = blkdev_releasepage,
1588 .direct_IO = blkdev_direct_IO,
1591 const struct file_operations def_blk_fops = {
1592 .open = blkdev_open,
1593 .release = blkdev_close,
1594 .llseek = block_llseek,
1595 .read = do_sync_read,
1596 .write = do_sync_write,
1597 .aio_read = blkdev_aio_read,
1598 .aio_write = blkdev_aio_write,
1599 .mmap = generic_file_mmap,
1600 .fsync = blkdev_fsync,
1601 .unlocked_ioctl = block_ioctl,
1602 #ifdef CONFIG_COMPAT
1603 .compat_ioctl = compat_blkdev_ioctl,
1604 #endif
1605 .splice_read = generic_file_splice_read,
1606 .splice_write = generic_file_splice_write,
1609 int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
1611 int res;
1612 mm_segment_t old_fs = get_fs();
1613 set_fs(KERNEL_DS);
1614 res = blkdev_ioctl(bdev, 0, cmd, arg);
1615 set_fs(old_fs);
1616 return res;
1619 EXPORT_SYMBOL(ioctl_by_bdev);
1622 * lookup_bdev - lookup a struct block_device by name
1623 * @pathname: special file representing the block device
1625 * Get a reference to the blockdevice at @pathname in the current
1626 * namespace if possible and return it. Return ERR_PTR(error)
1627 * otherwise.
1629 struct block_device *lookup_bdev(const char *pathname)
1631 struct block_device *bdev;
1632 struct inode *inode;
1633 struct path path;
1634 int error;
1636 if (!pathname || !*pathname)
1637 return ERR_PTR(-EINVAL);
1639 error = kern_path(pathname, LOOKUP_FOLLOW, &path);
1640 if (error)
1641 return ERR_PTR(error);
1643 inode = path.dentry->d_inode;
1644 error = -ENOTBLK;
1645 if (!S_ISBLK(inode->i_mode))
1646 goto fail;
1647 error = -EACCES;
1648 if (path.mnt->mnt_flags & MNT_NODEV)
1649 goto fail;
1650 error = -ENOMEM;
1651 bdev = bd_acquire(inode);
1652 if (!bdev)
1653 goto fail;
1654 out:
1655 path_put(&path);
1656 return bdev;
1657 fail:
1658 bdev = ERR_PTR(error);
1659 goto out;
1661 EXPORT_SYMBOL(lookup_bdev);
1663 int __invalidate_device(struct block_device *bdev, bool kill_dirty)
1665 struct super_block *sb = get_super(bdev);
1666 int res = 0;
1668 if (sb) {
1670 * no need to lock the super, get_super holds the
1671 * read mutex so the filesystem cannot go away
1672 * under us (->put_super runs with the write lock
1673 * hold).
1675 shrink_dcache_sb(sb);
1676 res = invalidate_inodes(sb, kill_dirty);
1677 drop_super(sb);
1679 invalidate_bdev(bdev);
1680 return res;
1682 EXPORT_SYMBOL(__invalidate_device);
1684 void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
1686 struct inode *inode, *old_inode = NULL;
1688 spin_lock(&inode_sb_list_lock);
1689 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
1690 struct address_space *mapping = inode->i_mapping;
1692 spin_lock(&inode->i_lock);
1693 if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
1694 mapping->nrpages == 0) {
1695 spin_unlock(&inode->i_lock);
1696 continue;
1698 __iget(inode);
1699 spin_unlock(&inode->i_lock);
1700 spin_unlock(&inode_sb_list_lock);
1702 * We hold a reference to 'inode' so it couldn't have been
1703 * removed from s_inodes list while we dropped the
1704 * inode_sb_list_lock. We cannot iput the inode now as we can
1705 * be holding the last reference and we cannot iput it under
1706 * inode_sb_list_lock. So we keep the reference and iput it
1707 * later.
1709 iput(old_inode);
1710 old_inode = inode;
1712 func(I_BDEV(inode), arg);
1714 spin_lock(&inode_sb_list_lock);
1716 spin_unlock(&inode_sb_list_lock);
1717 iput(old_inode);