ipv4: fix redirect handling
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / block_dev.c
blobb07f1da1de4e34470fd64af913c9366e0d6c8513
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/buffer_head.h>
20 #include <linux/pagevec.h>
21 #include <linux/writeback.h>
22 #include <linux/mpage.h>
23 #include <linux/mount.h>
24 #include <linux/uio.h>
25 #include <linux/namei.h>
26 #include <linux/log2.h>
27 #include <linux/kmemleak.h>
28 #include <asm/uaccess.h>
29 #include "internal.h"
31 struct bdev_inode {
32 struct block_device bdev;
33 struct inode vfs_inode;
36 static const struct address_space_operations def_blk_aops;
38 static inline struct bdev_inode *BDEV_I(struct inode *inode)
40 return container_of(inode, struct bdev_inode, vfs_inode);
43 inline struct block_device *I_BDEV(struct inode *inode)
45 return &BDEV_I(inode)->bdev;
47 EXPORT_SYMBOL(I_BDEV);
50 * Move the inode from its current bdi to a new bdi. If the inode is dirty we
51 * need to move it onto the dirty list of @dst so that the inode is always on
52 * the right list.
54 static void bdev_inode_switch_bdi(struct inode *inode,
55 struct backing_dev_info *dst)
57 struct backing_dev_info *old = inode->i_data.backing_dev_info;
59 if (unlikely(dst == old)) /* deadlock avoidance */
60 return;
61 bdi_lock_two(&old->wb, &dst->wb);
62 spin_lock(&inode->i_lock);
63 inode->i_data.backing_dev_info = dst;
64 if (inode->i_state & I_DIRTY)
65 list_move(&inode->i_wb_list, &dst->wb.b_dirty);
66 spin_unlock(&inode->i_lock);
67 spin_unlock(&old->wb.list_lock);
68 spin_unlock(&dst->wb.list_lock);
71 static sector_t max_block(struct block_device *bdev)
73 sector_t retval = ~((sector_t)0);
74 loff_t sz = i_size_read(bdev->bd_inode);
76 if (sz) {
77 unsigned int size = block_size(bdev);
78 unsigned int sizebits = blksize_bits(size);
79 retval = (sz >> sizebits);
81 return retval;
84 /* Kill _all_ buffers and pagecache , dirty or not.. */
85 static void kill_bdev(struct block_device *bdev)
87 if (bdev->bd_inode->i_mapping->nrpages == 0)
88 return;
89 invalidate_bh_lrus();
90 truncate_inode_pages(bdev->bd_inode->i_mapping, 0);
93 int set_blocksize(struct block_device *bdev, int size)
95 /* Size must be a power of two, and between 512 and PAGE_SIZE */
96 if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
97 return -EINVAL;
99 /* Size cannot be smaller than the size supported by the device */
100 if (size < bdev_logical_block_size(bdev))
101 return -EINVAL;
103 /* Don't change the size if it is same as current */
104 if (bdev->bd_block_size != size) {
105 sync_blockdev(bdev);
106 bdev->bd_block_size = size;
107 bdev->bd_inode->i_blkbits = blksize_bits(size);
108 kill_bdev(bdev);
110 return 0;
113 EXPORT_SYMBOL(set_blocksize);
115 int sb_set_blocksize(struct super_block *sb, int size)
117 if (set_blocksize(sb->s_bdev, size))
118 return 0;
119 /* If we get here, we know size is power of two
120 * and it's value is between 512 and PAGE_SIZE */
121 sb->s_blocksize = size;
122 sb->s_blocksize_bits = blksize_bits(size);
123 return sb->s_blocksize;
126 EXPORT_SYMBOL(sb_set_blocksize);
128 int sb_min_blocksize(struct super_block *sb, int size)
130 int minsize = bdev_logical_block_size(sb->s_bdev);
131 if (size < minsize)
132 size = minsize;
133 return sb_set_blocksize(sb, size);
136 EXPORT_SYMBOL(sb_min_blocksize);
138 static int
139 blkdev_get_block(struct inode *inode, sector_t iblock,
140 struct buffer_head *bh, int create)
142 if (iblock >= max_block(I_BDEV(inode))) {
143 if (create)
144 return -EIO;
147 * for reads, we're just trying to fill a partial page.
148 * return a hole, they will have to call get_block again
149 * before they can fill it, and they will get -EIO at that
150 * time
152 return 0;
154 bh->b_bdev = I_BDEV(inode);
155 bh->b_blocknr = iblock;
156 set_buffer_mapped(bh);
157 return 0;
160 static int
161 blkdev_get_blocks(struct inode *inode, sector_t iblock,
162 struct buffer_head *bh, int create)
164 sector_t end_block = max_block(I_BDEV(inode));
165 unsigned long max_blocks = bh->b_size >> inode->i_blkbits;
167 if ((iblock + max_blocks) > end_block) {
168 max_blocks = end_block - iblock;
169 if ((long)max_blocks <= 0) {
170 if (create)
171 return -EIO; /* write fully beyond EOF */
173 * It is a read which is fully beyond EOF. We return
174 * a !buffer_mapped buffer
176 max_blocks = 0;
180 bh->b_bdev = I_BDEV(inode);
181 bh->b_blocknr = iblock;
182 bh->b_size = max_blocks << inode->i_blkbits;
183 if (max_blocks)
184 set_buffer_mapped(bh);
185 return 0;
188 static ssize_t
189 blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
190 loff_t offset, unsigned long nr_segs)
192 struct file *file = iocb->ki_filp;
193 struct inode *inode = file->f_mapping->host;
195 return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset,
196 nr_segs, blkdev_get_blocks, NULL, NULL, 0);
199 int __sync_blockdev(struct block_device *bdev, int wait)
201 if (!bdev)
202 return 0;
203 if (!wait)
204 return filemap_flush(bdev->bd_inode->i_mapping);
205 return filemap_write_and_wait(bdev->bd_inode->i_mapping);
209 * Write out and wait upon all the dirty data associated with a block
210 * device via its mapping. Does not take the superblock lock.
212 int sync_blockdev(struct block_device *bdev)
214 return __sync_blockdev(bdev, 1);
216 EXPORT_SYMBOL(sync_blockdev);
219 * Write out and wait upon all dirty data associated with this
220 * device. Filesystem data as well as the underlying block
221 * device. Takes the superblock lock.
223 int fsync_bdev(struct block_device *bdev)
225 struct super_block *sb = get_super(bdev);
226 if (sb) {
227 int res = sync_filesystem(sb);
228 drop_super(sb);
229 return res;
231 return sync_blockdev(bdev);
233 EXPORT_SYMBOL(fsync_bdev);
236 * freeze_bdev -- lock a filesystem and force it into a consistent state
237 * @bdev: blockdevice to lock
239 * If a superblock is found on this device, we take the s_umount semaphore
240 * on it to make sure nobody unmounts until the snapshot creation is done.
241 * The reference counter (bd_fsfreeze_count) guarantees that only the last
242 * unfreeze process can unfreeze the frozen filesystem actually when multiple
243 * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
244 * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
245 * actually.
247 struct super_block *freeze_bdev(struct block_device *bdev)
249 struct super_block *sb;
250 int error = 0;
252 mutex_lock(&bdev->bd_fsfreeze_mutex);
253 if (++bdev->bd_fsfreeze_count > 1) {
255 * We don't even need to grab a reference - the first call
256 * to freeze_bdev grab an active reference and only the last
257 * thaw_bdev drops it.
259 sb = get_super(bdev);
260 drop_super(sb);
261 mutex_unlock(&bdev->bd_fsfreeze_mutex);
262 return sb;
265 sb = get_active_super(bdev);
266 if (!sb)
267 goto out;
268 error = freeze_super(sb);
269 if (error) {
270 deactivate_super(sb);
271 bdev->bd_fsfreeze_count--;
272 mutex_unlock(&bdev->bd_fsfreeze_mutex);
273 return ERR_PTR(error);
275 deactivate_super(sb);
276 out:
277 sync_blockdev(bdev);
278 mutex_unlock(&bdev->bd_fsfreeze_mutex);
279 return sb; /* thaw_bdev releases s->s_umount */
281 EXPORT_SYMBOL(freeze_bdev);
284 * thaw_bdev -- unlock filesystem
285 * @bdev: blockdevice to unlock
286 * @sb: associated superblock
288 * Unlocks the filesystem and marks it writeable again after freeze_bdev().
290 int thaw_bdev(struct block_device *bdev, struct super_block *sb)
292 int error = -EINVAL;
294 mutex_lock(&bdev->bd_fsfreeze_mutex);
295 if (!bdev->bd_fsfreeze_count)
296 goto out;
298 error = 0;
299 if (--bdev->bd_fsfreeze_count > 0)
300 goto out;
302 if (!sb)
303 goto out;
305 error = thaw_super(sb);
306 if (error) {
307 bdev->bd_fsfreeze_count++;
308 mutex_unlock(&bdev->bd_fsfreeze_mutex);
309 return error;
311 out:
312 mutex_unlock(&bdev->bd_fsfreeze_mutex);
313 return 0;
315 EXPORT_SYMBOL(thaw_bdev);
317 static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
319 return block_write_full_page(page, blkdev_get_block, wbc);
322 static int blkdev_readpage(struct file * file, struct page * page)
324 return block_read_full_page(page, blkdev_get_block);
327 static int blkdev_write_begin(struct file *file, struct address_space *mapping,
328 loff_t pos, unsigned len, unsigned flags,
329 struct page **pagep, void **fsdata)
331 return block_write_begin(mapping, pos, len, flags, pagep,
332 blkdev_get_block);
335 static int blkdev_write_end(struct file *file, struct address_space *mapping,
336 loff_t pos, unsigned len, unsigned copied,
337 struct page *page, void *fsdata)
339 int ret;
340 ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
342 unlock_page(page);
343 page_cache_release(page);
345 return ret;
349 * private llseek:
350 * for a block special file file->f_path.dentry->d_inode->i_size is zero
351 * so we compute the size by hand (just as in block_read/write above)
353 static loff_t block_llseek(struct file *file, loff_t offset, int origin)
355 struct inode *bd_inode = file->f_mapping->host;
356 loff_t size;
357 loff_t retval;
359 mutex_lock(&bd_inode->i_mutex);
360 size = i_size_read(bd_inode);
362 retval = -EINVAL;
363 switch (origin) {
364 case SEEK_END:
365 offset += size;
366 break;
367 case SEEK_CUR:
368 offset += file->f_pos;
369 case SEEK_SET:
370 break;
371 default:
372 goto out;
374 if (offset >= 0 && offset <= size) {
375 if (offset != file->f_pos) {
376 file->f_pos = offset;
378 retval = offset;
380 out:
381 mutex_unlock(&bd_inode->i_mutex);
382 return retval;
385 int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
387 struct inode *bd_inode = filp->f_mapping->host;
388 struct block_device *bdev = I_BDEV(bd_inode);
389 int error;
391 error = filemap_write_and_wait_range(filp->f_mapping, start, end);
392 if (error)
393 return error;
396 * There is no need to serialise calls to blkdev_issue_flush with
397 * i_mutex and doing so causes performance issues with concurrent
398 * O_SYNC writers to a block device.
400 error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL);
401 if (error == -EOPNOTSUPP)
402 error = 0;
404 return error;
406 EXPORT_SYMBOL(blkdev_fsync);
409 * pseudo-fs
412 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
413 static struct kmem_cache * bdev_cachep __read_mostly;
415 static struct inode *bdev_alloc_inode(struct super_block *sb)
417 struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
418 if (!ei)
419 return NULL;
420 return &ei->vfs_inode;
423 static void bdev_i_callback(struct rcu_head *head)
425 struct inode *inode = container_of(head, struct inode, i_rcu);
426 struct bdev_inode *bdi = BDEV_I(inode);
428 INIT_LIST_HEAD(&inode->i_dentry);
429 kmem_cache_free(bdev_cachep, bdi);
432 static void bdev_destroy_inode(struct inode *inode)
434 call_rcu(&inode->i_rcu, bdev_i_callback);
437 static void init_once(void *foo)
439 struct bdev_inode *ei = (struct bdev_inode *) foo;
440 struct block_device *bdev = &ei->bdev;
442 memset(bdev, 0, sizeof(*bdev));
443 mutex_init(&bdev->bd_mutex);
444 INIT_LIST_HEAD(&bdev->bd_inodes);
445 INIT_LIST_HEAD(&bdev->bd_list);
446 #ifdef CONFIG_SYSFS
447 INIT_LIST_HEAD(&bdev->bd_holder_disks);
448 #endif
449 inode_init_once(&ei->vfs_inode);
450 /* Initialize mutex for freeze. */
451 mutex_init(&bdev->bd_fsfreeze_mutex);
454 static inline void __bd_forget(struct inode *inode)
456 list_del_init(&inode->i_devices);
457 inode->i_bdev = NULL;
458 inode->i_mapping = &inode->i_data;
461 static void bdev_evict_inode(struct inode *inode)
463 struct block_device *bdev = &BDEV_I(inode)->bdev;
464 struct list_head *p;
465 truncate_inode_pages(&inode->i_data, 0);
466 invalidate_inode_buffers(inode); /* is it needed here? */
467 end_writeback(inode);
468 spin_lock(&bdev_lock);
469 while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) {
470 __bd_forget(list_entry(p, struct inode, i_devices));
472 list_del_init(&bdev->bd_list);
473 spin_unlock(&bdev_lock);
476 static const struct super_operations bdev_sops = {
477 .statfs = simple_statfs,
478 .alloc_inode = bdev_alloc_inode,
479 .destroy_inode = bdev_destroy_inode,
480 .drop_inode = generic_delete_inode,
481 .evict_inode = bdev_evict_inode,
484 static struct dentry *bd_mount(struct file_system_type *fs_type,
485 int flags, const char *dev_name, void *data)
487 return mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, 0x62646576);
490 static struct file_system_type bd_type = {
491 .name = "bdev",
492 .mount = bd_mount,
493 .kill_sb = kill_anon_super,
496 struct super_block *blockdev_superblock __read_mostly;
498 void __init bdev_cache_init(void)
500 int err;
501 struct vfsmount *bd_mnt;
503 bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
504 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
505 SLAB_MEM_SPREAD|SLAB_PANIC),
506 init_once);
507 err = register_filesystem(&bd_type);
508 if (err)
509 panic("Cannot register bdev pseudo-fs");
510 bd_mnt = kern_mount(&bd_type);
511 if (IS_ERR(bd_mnt))
512 panic("Cannot create bdev pseudo-fs");
514 * This vfsmount structure is only used to obtain the
515 * blockdev_superblock, so tell kmemleak not to report it.
517 kmemleak_not_leak(bd_mnt);
518 blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */
522 * Most likely _very_ bad one - but then it's hardly critical for small
523 * /dev and can be fixed when somebody will need really large one.
524 * Keep in mind that it will be fed through icache hash function too.
526 static inline unsigned long hash(dev_t dev)
528 return MAJOR(dev)+MINOR(dev);
531 static int bdev_test(struct inode *inode, void *data)
533 return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
536 static int bdev_set(struct inode *inode, void *data)
538 BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
539 return 0;
542 static LIST_HEAD(all_bdevs);
544 struct block_device *bdget(dev_t dev)
546 struct block_device *bdev;
547 struct inode *inode;
549 inode = iget5_locked(blockdev_superblock, hash(dev),
550 bdev_test, bdev_set, &dev);
552 if (!inode)
553 return NULL;
555 bdev = &BDEV_I(inode)->bdev;
557 if (inode->i_state & I_NEW) {
558 bdev->bd_contains = NULL;
559 bdev->bd_super = NULL;
560 bdev->bd_inode = inode;
561 bdev->bd_block_size = (1 << inode->i_blkbits);
562 bdev->bd_part_count = 0;
563 bdev->bd_invalidated = 0;
564 inode->i_mode = S_IFBLK;
565 inode->i_rdev = dev;
566 inode->i_bdev = bdev;
567 inode->i_data.a_ops = &def_blk_aops;
568 mapping_set_gfp_mask(&inode->i_data, GFP_USER);
569 inode->i_data.backing_dev_info = &default_backing_dev_info;
570 spin_lock(&bdev_lock);
571 list_add(&bdev->bd_list, &all_bdevs);
572 spin_unlock(&bdev_lock);
573 unlock_new_inode(inode);
575 return bdev;
578 EXPORT_SYMBOL(bdget);
581 * bdgrab -- Grab a reference to an already referenced block device
582 * @bdev: Block device to grab a reference to.
584 struct block_device *bdgrab(struct block_device *bdev)
586 ihold(bdev->bd_inode);
587 return bdev;
590 long nr_blockdev_pages(void)
592 struct block_device *bdev;
593 long ret = 0;
594 spin_lock(&bdev_lock);
595 list_for_each_entry(bdev, &all_bdevs, bd_list) {
596 ret += bdev->bd_inode->i_mapping->nrpages;
598 spin_unlock(&bdev_lock);
599 return ret;
602 void bdput(struct block_device *bdev)
604 iput(bdev->bd_inode);
607 EXPORT_SYMBOL(bdput);
609 static struct block_device *bd_acquire(struct inode *inode)
611 struct block_device *bdev;
613 spin_lock(&bdev_lock);
614 bdev = inode->i_bdev;
615 if (bdev) {
616 ihold(bdev->bd_inode);
617 spin_unlock(&bdev_lock);
618 return bdev;
620 spin_unlock(&bdev_lock);
622 bdev = bdget(inode->i_rdev);
623 if (bdev) {
624 spin_lock(&bdev_lock);
625 if (!inode->i_bdev) {
627 * We take an additional reference to bd_inode,
628 * and it's released in clear_inode() of inode.
629 * So, we can access it via ->i_mapping always
630 * without igrab().
632 ihold(bdev->bd_inode);
633 inode->i_bdev = bdev;
634 inode->i_mapping = bdev->bd_inode->i_mapping;
635 list_add(&inode->i_devices, &bdev->bd_inodes);
637 spin_unlock(&bdev_lock);
639 return bdev;
642 /* Call when you free inode */
644 void bd_forget(struct inode *inode)
646 struct block_device *bdev = NULL;
648 spin_lock(&bdev_lock);
649 if (inode->i_bdev) {
650 if (!sb_is_blkdev_sb(inode->i_sb))
651 bdev = inode->i_bdev;
652 __bd_forget(inode);
654 spin_unlock(&bdev_lock);
656 if (bdev)
657 iput(bdev->bd_inode);
661 * bd_may_claim - test whether a block device can be claimed
662 * @bdev: block device of interest
663 * @whole: whole block device containing @bdev, may equal @bdev
664 * @holder: holder trying to claim @bdev
666 * Test whether @bdev can be claimed by @holder.
668 * CONTEXT:
669 * spin_lock(&bdev_lock).
671 * RETURNS:
672 * %true if @bdev can be claimed, %false otherwise.
674 static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
675 void *holder)
677 if (bdev->bd_holder == holder)
678 return true; /* already a holder */
679 else if (bdev->bd_holder != NULL)
680 return false; /* held by someone else */
681 else if (bdev->bd_contains == bdev)
682 return true; /* is a whole device which isn't held */
684 else if (whole->bd_holder == bd_may_claim)
685 return true; /* is a partition of a device that is being partitioned */
686 else if (whole->bd_holder != NULL)
687 return false; /* is a partition of a held device */
688 else
689 return true; /* is a partition of an un-held device */
693 * bd_prepare_to_claim - prepare to claim a block device
694 * @bdev: block device of interest
695 * @whole: the whole device containing @bdev, may equal @bdev
696 * @holder: holder trying to claim @bdev
698 * Prepare to claim @bdev. This function fails if @bdev is already
699 * claimed by another holder and waits if another claiming is in
700 * progress. This function doesn't actually claim. On successful
701 * return, the caller has ownership of bd_claiming and bd_holder[s].
703 * CONTEXT:
704 * spin_lock(&bdev_lock). Might release bdev_lock, sleep and regrab
705 * it multiple times.
707 * RETURNS:
708 * 0 if @bdev can be claimed, -EBUSY otherwise.
710 static int bd_prepare_to_claim(struct block_device *bdev,
711 struct block_device *whole, void *holder)
713 retry:
714 /* if someone else claimed, fail */
715 if (!bd_may_claim(bdev, whole, holder))
716 return -EBUSY;
718 /* if claiming is already in progress, wait for it to finish */
719 if (whole->bd_claiming) {
720 wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
721 DEFINE_WAIT(wait);
723 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
724 spin_unlock(&bdev_lock);
725 schedule();
726 finish_wait(wq, &wait);
727 spin_lock(&bdev_lock);
728 goto retry;
731 /* yay, all mine */
732 return 0;
736 * bd_start_claiming - start claiming a block device
737 * @bdev: block device of interest
738 * @holder: holder trying to claim @bdev
740 * @bdev is about to be opened exclusively. Check @bdev can be opened
741 * exclusively and mark that an exclusive open is in progress. Each
742 * successful call to this function must be matched with a call to
743 * either bd_finish_claiming() or bd_abort_claiming() (which do not
744 * fail).
746 * This function is used to gain exclusive access to the block device
747 * without actually causing other exclusive open attempts to fail. It
748 * should be used when the open sequence itself requires exclusive
749 * access but may subsequently fail.
751 * CONTEXT:
752 * Might sleep.
754 * RETURNS:
755 * Pointer to the block device containing @bdev on success, ERR_PTR()
756 * value on failure.
758 static struct block_device *bd_start_claiming(struct block_device *bdev,
759 void *holder)
761 struct gendisk *disk;
762 struct block_device *whole;
763 int partno, err;
765 might_sleep();
768 * @bdev might not have been initialized properly yet, look up
769 * and grab the outer block device the hard way.
771 disk = get_gendisk(bdev->bd_dev, &partno);
772 if (!disk)
773 return ERR_PTR(-ENXIO);
776 * Normally, @bdev should equal what's returned from bdget_disk()
777 * if partno is 0; however, some drivers (floppy) use multiple
778 * bdev's for the same physical device and @bdev may be one of the
779 * aliases. Keep @bdev if partno is 0. This means claimer
780 * tracking is broken for those devices but it has always been that
781 * way.
783 if (partno)
784 whole = bdget_disk(disk, 0);
785 else
786 whole = bdgrab(bdev);
788 module_put(disk->fops->owner);
789 put_disk(disk);
790 if (!whole)
791 return ERR_PTR(-ENOMEM);
793 /* prepare to claim, if successful, mark claiming in progress */
794 spin_lock(&bdev_lock);
796 err = bd_prepare_to_claim(bdev, whole, holder);
797 if (err == 0) {
798 whole->bd_claiming = holder;
799 spin_unlock(&bdev_lock);
800 return whole;
801 } else {
802 spin_unlock(&bdev_lock);
803 bdput(whole);
804 return ERR_PTR(err);
808 #ifdef CONFIG_SYSFS
809 struct bd_holder_disk {
810 struct list_head list;
811 struct gendisk *disk;
812 int refcnt;
815 static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
816 struct gendisk *disk)
818 struct bd_holder_disk *holder;
820 list_for_each_entry(holder, &bdev->bd_holder_disks, list)
821 if (holder->disk == disk)
822 return holder;
823 return NULL;
826 static int add_symlink(struct kobject *from, struct kobject *to)
828 return sysfs_create_link(from, to, kobject_name(to));
831 static void del_symlink(struct kobject *from, struct kobject *to)
833 sysfs_remove_link(from, kobject_name(to));
837 * bd_link_disk_holder - create symlinks between holding disk and slave bdev
838 * @bdev: the claimed slave bdev
839 * @disk: the holding disk
841 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
843 * This functions creates the following sysfs symlinks.
845 * - from "slaves" directory of the holder @disk to the claimed @bdev
846 * - from "holders" directory of the @bdev to the holder @disk
848 * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
849 * passed to bd_link_disk_holder(), then:
851 * /sys/block/dm-0/slaves/sda --> /sys/block/sda
852 * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
854 * The caller must have claimed @bdev before calling this function and
855 * ensure that both @bdev and @disk are valid during the creation and
856 * lifetime of these symlinks.
858 * CONTEXT:
859 * Might sleep.
861 * RETURNS:
862 * 0 on success, -errno on failure.
864 int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
866 struct bd_holder_disk *holder;
867 int ret = 0;
869 mutex_lock(&bdev->bd_mutex);
871 WARN_ON_ONCE(!bdev->bd_holder);
873 /* FIXME: remove the following once add_disk() handles errors */
874 if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
875 goto out_unlock;
877 holder = bd_find_holder_disk(bdev, disk);
878 if (holder) {
879 holder->refcnt++;
880 goto out_unlock;
883 holder = kzalloc(sizeof(*holder), GFP_KERNEL);
884 if (!holder) {
885 ret = -ENOMEM;
886 goto out_unlock;
889 INIT_LIST_HEAD(&holder->list);
890 holder->disk = disk;
891 holder->refcnt = 1;
893 ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
894 if (ret)
895 goto out_free;
897 ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
898 if (ret)
899 goto out_del;
901 * bdev could be deleted beneath us which would implicitly destroy
902 * the holder directory. Hold on to it.
904 kobject_get(bdev->bd_part->holder_dir);
906 list_add(&holder->list, &bdev->bd_holder_disks);
907 goto out_unlock;
909 out_del:
910 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
911 out_free:
912 kfree(holder);
913 out_unlock:
914 mutex_unlock(&bdev->bd_mutex);
915 return ret;
917 EXPORT_SYMBOL_GPL(bd_link_disk_holder);
920 * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
921 * @bdev: the calimed slave bdev
922 * @disk: the holding disk
924 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
926 * CONTEXT:
927 * Might sleep.
929 void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
931 struct bd_holder_disk *holder;
933 mutex_lock(&bdev->bd_mutex);
935 holder = bd_find_holder_disk(bdev, disk);
937 if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
938 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
939 del_symlink(bdev->bd_part->holder_dir,
940 &disk_to_dev(disk)->kobj);
941 kobject_put(bdev->bd_part->holder_dir);
942 list_del_init(&holder->list);
943 kfree(holder);
946 mutex_unlock(&bdev->bd_mutex);
948 EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
949 #endif
952 * flush_disk - invalidates all buffer-cache entries on a disk
954 * @bdev: struct block device to be flushed
955 * @kill_dirty: flag to guide handling of dirty inodes
957 * Invalidates all buffer-cache entries on a disk. It should be called
958 * when a disk has been changed -- either by a media change or online
959 * resize.
961 static void flush_disk(struct block_device *bdev, bool kill_dirty)
963 if (__invalidate_device(bdev, kill_dirty)) {
964 char name[BDEVNAME_SIZE] = "";
966 if (bdev->bd_disk)
967 disk_name(bdev->bd_disk, 0, name);
968 printk(KERN_WARNING "VFS: busy inodes on changed media or "
969 "resized disk %s\n", name);
972 if (!bdev->bd_disk)
973 return;
974 if (disk_part_scan_enabled(bdev->bd_disk))
975 bdev->bd_invalidated = 1;
979 * check_disk_size_change - checks for disk size change and adjusts bdev size.
980 * @disk: struct gendisk to check
981 * @bdev: struct bdev to adjust.
983 * This routine checks to see if the bdev size does not match the disk size
984 * and adjusts it if it differs.
986 void check_disk_size_change(struct gendisk *disk, struct block_device *bdev)
988 loff_t disk_size, bdev_size;
990 disk_size = (loff_t)get_capacity(disk) << 9;
991 bdev_size = i_size_read(bdev->bd_inode);
992 if (disk_size != bdev_size) {
993 char name[BDEVNAME_SIZE];
995 disk_name(disk, 0, name);
996 printk(KERN_INFO
997 "%s: detected capacity change from %lld to %lld\n",
998 name, bdev_size, disk_size);
999 i_size_write(bdev->bd_inode, disk_size);
1000 flush_disk(bdev, false);
1003 EXPORT_SYMBOL(check_disk_size_change);
1006 * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
1007 * @disk: struct gendisk to be revalidated
1009 * This routine is a wrapper for lower-level driver's revalidate_disk
1010 * call-backs. It is used to do common pre and post operations needed
1011 * for all revalidate_disk operations.
1013 int revalidate_disk(struct gendisk *disk)
1015 struct block_device *bdev;
1016 int ret = 0;
1018 if (disk->fops->revalidate_disk)
1019 ret = disk->fops->revalidate_disk(disk);
1021 bdev = bdget_disk(disk, 0);
1022 if (!bdev)
1023 return ret;
1025 mutex_lock(&bdev->bd_mutex);
1026 check_disk_size_change(disk, bdev);
1027 mutex_unlock(&bdev->bd_mutex);
1028 bdput(bdev);
1029 return ret;
1031 EXPORT_SYMBOL(revalidate_disk);
1034 * This routine checks whether a removable media has been changed,
1035 * and invalidates all buffer-cache-entries in that case. This
1036 * is a relatively slow routine, so we have to try to minimize using
1037 * it. Thus it is called only upon a 'mount' or 'open'. This
1038 * is the best way of combining speed and utility, I think.
1039 * People changing diskettes in the middle of an operation deserve
1040 * to lose :-)
1042 int check_disk_change(struct block_device *bdev)
1044 struct gendisk *disk = bdev->bd_disk;
1045 const struct block_device_operations *bdops = disk->fops;
1046 unsigned int events;
1048 events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
1049 DISK_EVENT_EJECT_REQUEST);
1050 if (!(events & DISK_EVENT_MEDIA_CHANGE))
1051 return 0;
1053 flush_disk(bdev, true);
1054 if (bdops->revalidate_disk)
1055 bdops->revalidate_disk(bdev->bd_disk);
1056 return 1;
1059 EXPORT_SYMBOL(check_disk_change);
1061 void bd_set_size(struct block_device *bdev, loff_t size)
1063 unsigned bsize = bdev_logical_block_size(bdev);
1065 bdev->bd_inode->i_size = size;
1066 while (bsize < PAGE_CACHE_SIZE) {
1067 if (size & bsize)
1068 break;
1069 bsize <<= 1;
1071 bdev->bd_block_size = bsize;
1072 bdev->bd_inode->i_blkbits = blksize_bits(bsize);
1074 EXPORT_SYMBOL(bd_set_size);
1076 static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
1079 * bd_mutex locking:
1081 * mutex_lock(part->bd_mutex)
1082 * mutex_lock_nested(whole->bd_mutex, 1)
1085 static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
1087 struct gendisk *disk;
1088 struct module *owner;
1089 int ret;
1090 int partno;
1091 int perm = 0;
1093 if (mode & FMODE_READ)
1094 perm |= MAY_READ;
1095 if (mode & FMODE_WRITE)
1096 perm |= MAY_WRITE;
1098 * hooks: /n/, see "layering violations".
1100 if (!for_part) {
1101 ret = devcgroup_inode_permission(bdev->bd_inode, perm);
1102 if (ret != 0) {
1103 bdput(bdev);
1104 return ret;
1108 restart:
1110 ret = -ENXIO;
1111 disk = get_gendisk(bdev->bd_dev, &partno);
1112 if (!disk)
1113 goto out;
1114 owner = disk->fops->owner;
1116 disk_block_events(disk);
1117 mutex_lock_nested(&bdev->bd_mutex, for_part);
1118 if (!bdev->bd_openers) {
1119 bdev->bd_disk = disk;
1120 bdev->bd_contains = bdev;
1121 if (!partno) {
1122 struct backing_dev_info *bdi;
1124 ret = -ENXIO;
1125 bdev->bd_part = disk_get_part(disk, partno);
1126 if (!bdev->bd_part)
1127 goto out_clear;
1129 ret = 0;
1130 if (disk->fops->open) {
1131 ret = disk->fops->open(bdev, mode);
1132 if (ret == -ERESTARTSYS) {
1133 /* Lost a race with 'disk' being
1134 * deleted, try again.
1135 * See md.c
1137 disk_put_part(bdev->bd_part);
1138 bdev->bd_part = NULL;
1139 bdev->bd_disk = NULL;
1140 mutex_unlock(&bdev->bd_mutex);
1141 disk_unblock_events(disk);
1142 put_disk(disk);
1143 module_put(owner);
1144 goto restart;
1148 if (!ret && !bdev->bd_openers) {
1149 bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
1150 bdi = blk_get_backing_dev_info(bdev);
1151 if (bdi == NULL)
1152 bdi = &default_backing_dev_info;
1153 bdev_inode_switch_bdi(bdev->bd_inode, bdi);
1157 * If the device is invalidated, rescan partition
1158 * if open succeeded or failed with -ENOMEDIUM.
1159 * The latter is necessary to prevent ghost
1160 * partitions on a removed medium.
1162 if (bdev->bd_invalidated && (!ret || ret == -ENOMEDIUM))
1163 rescan_partitions(disk, bdev);
1164 if (ret)
1165 goto out_clear;
1166 } else {
1167 struct block_device *whole;
1168 whole = bdget_disk(disk, 0);
1169 ret = -ENOMEM;
1170 if (!whole)
1171 goto out_clear;
1172 BUG_ON(for_part);
1173 ret = __blkdev_get(whole, mode, 1);
1174 if (ret)
1175 goto out_clear;
1176 bdev->bd_contains = whole;
1177 bdev_inode_switch_bdi(bdev->bd_inode,
1178 whole->bd_inode->i_data.backing_dev_info);
1179 bdev->bd_part = disk_get_part(disk, partno);
1180 if (!(disk->flags & GENHD_FL_UP) ||
1181 !bdev->bd_part || !bdev->bd_part->nr_sects) {
1182 ret = -ENXIO;
1183 goto out_clear;
1185 bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
1187 } else {
1188 if (bdev->bd_contains == bdev) {
1189 ret = 0;
1190 if (bdev->bd_disk->fops->open)
1191 ret = bdev->bd_disk->fops->open(bdev, mode);
1192 /* the same as first opener case, read comment there */
1193 if (bdev->bd_invalidated && (!ret || ret == -ENOMEDIUM))
1194 rescan_partitions(bdev->bd_disk, bdev);
1195 if (ret)
1196 goto out_unlock_bdev;
1198 /* only one opener holds refs to the module and disk */
1199 put_disk(disk);
1200 module_put(owner);
1202 bdev->bd_openers++;
1203 if (for_part)
1204 bdev->bd_part_count++;
1205 mutex_unlock(&bdev->bd_mutex);
1206 disk_unblock_events(disk);
1207 return 0;
1209 out_clear:
1210 disk_put_part(bdev->bd_part);
1211 bdev->bd_disk = NULL;
1212 bdev->bd_part = NULL;
1213 bdev_inode_switch_bdi(bdev->bd_inode, &default_backing_dev_info);
1214 if (bdev != bdev->bd_contains)
1215 __blkdev_put(bdev->bd_contains, mode, 1);
1216 bdev->bd_contains = NULL;
1217 out_unlock_bdev:
1218 mutex_unlock(&bdev->bd_mutex);
1219 disk_unblock_events(disk);
1220 put_disk(disk);
1221 module_put(owner);
1222 out:
1223 bdput(bdev);
1225 return ret;
1229 * blkdev_get - open a block device
1230 * @bdev: block_device to open
1231 * @mode: FMODE_* mask
1232 * @holder: exclusive holder identifier
1234 * Open @bdev with @mode. If @mode includes %FMODE_EXCL, @bdev is
1235 * open with exclusive access. Specifying %FMODE_EXCL with %NULL
1236 * @holder is invalid. Exclusive opens may nest for the same @holder.
1238 * On success, the reference count of @bdev is unchanged. On failure,
1239 * @bdev is put.
1241 * CONTEXT:
1242 * Might sleep.
1244 * RETURNS:
1245 * 0 on success, -errno on failure.
1247 int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
1249 struct block_device *whole = NULL;
1250 int res;
1252 WARN_ON_ONCE((mode & FMODE_EXCL) && !holder);
1254 if ((mode & FMODE_EXCL) && holder) {
1255 whole = bd_start_claiming(bdev, holder);
1256 if (IS_ERR(whole)) {
1257 bdput(bdev);
1258 return PTR_ERR(whole);
1262 res = __blkdev_get(bdev, mode, 0);
1264 if (whole) {
1265 struct gendisk *disk = whole->bd_disk;
1267 /* finish claiming */
1268 mutex_lock(&bdev->bd_mutex);
1269 spin_lock(&bdev_lock);
1271 if (!res) {
1272 BUG_ON(!bd_may_claim(bdev, whole, holder));
1274 * Note that for a whole device bd_holders
1275 * will be incremented twice, and bd_holder
1276 * will be set to bd_may_claim before being
1277 * set to holder
1279 whole->bd_holders++;
1280 whole->bd_holder = bd_may_claim;
1281 bdev->bd_holders++;
1282 bdev->bd_holder = holder;
1285 /* tell others that we're done */
1286 BUG_ON(whole->bd_claiming != holder);
1287 whole->bd_claiming = NULL;
1288 wake_up_bit(&whole->bd_claiming, 0);
1290 spin_unlock(&bdev_lock);
1293 * Block event polling for write claims if requested. Any
1294 * write holder makes the write_holder state stick until
1295 * all are released. This is good enough and tracking
1296 * individual writeable reference is too fragile given the
1297 * way @mode is used in blkdev_get/put().
1299 if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder &&
1300 (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
1301 bdev->bd_write_holder = true;
1302 disk_block_events(disk);
1305 mutex_unlock(&bdev->bd_mutex);
1306 bdput(whole);
1309 return res;
1311 EXPORT_SYMBOL(blkdev_get);
1314 * blkdev_get_by_path - open a block device by name
1315 * @path: path to the block device to open
1316 * @mode: FMODE_* mask
1317 * @holder: exclusive holder identifier
1319 * Open the blockdevice described by the device file at @path. @mode
1320 * and @holder are identical to blkdev_get().
1322 * On success, the returned block_device has reference count of one.
1324 * CONTEXT:
1325 * Might sleep.
1327 * RETURNS:
1328 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1330 struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
1331 void *holder)
1333 struct block_device *bdev;
1334 int err;
1336 bdev = lookup_bdev(path);
1337 if (IS_ERR(bdev))
1338 return bdev;
1340 err = blkdev_get(bdev, mode, holder);
1341 if (err)
1342 return ERR_PTR(err);
1344 if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) {
1345 blkdev_put(bdev, mode);
1346 return ERR_PTR(-EACCES);
1349 return bdev;
1351 EXPORT_SYMBOL(blkdev_get_by_path);
1354 * blkdev_get_by_dev - open a block device by device number
1355 * @dev: device number of block device to open
1356 * @mode: FMODE_* mask
1357 * @holder: exclusive holder identifier
1359 * Open the blockdevice described by device number @dev. @mode and
1360 * @holder are identical to blkdev_get().
1362 * Use it ONLY if you really do not have anything better - i.e. when
1363 * you are behind a truly sucky interface and all you are given is a
1364 * device number. _Never_ to be used for internal purposes. If you
1365 * ever need it - reconsider your API.
1367 * On success, the returned block_device has reference count of one.
1369 * CONTEXT:
1370 * Might sleep.
1372 * RETURNS:
1373 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1375 struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
1377 struct block_device *bdev;
1378 int err;
1380 bdev = bdget(dev);
1381 if (!bdev)
1382 return ERR_PTR(-ENOMEM);
1384 err = blkdev_get(bdev, mode, holder);
1385 if (err)
1386 return ERR_PTR(err);
1388 return bdev;
1390 EXPORT_SYMBOL(blkdev_get_by_dev);
1392 static int blkdev_open(struct inode * inode, struct file * filp)
1394 struct block_device *bdev;
1397 * Preserve backwards compatibility and allow large file access
1398 * even if userspace doesn't ask for it explicitly. Some mkfs
1399 * binary needs it. We might want to drop this workaround
1400 * during an unstable branch.
1402 filp->f_flags |= O_LARGEFILE;
1404 if (filp->f_flags & O_NDELAY)
1405 filp->f_mode |= FMODE_NDELAY;
1406 if (filp->f_flags & O_EXCL)
1407 filp->f_mode |= FMODE_EXCL;
1408 if ((filp->f_flags & O_ACCMODE) == 3)
1409 filp->f_mode |= FMODE_WRITE_IOCTL;
1411 bdev = bd_acquire(inode);
1412 if (bdev == NULL)
1413 return -ENOMEM;
1415 filp->f_mapping = bdev->bd_inode->i_mapping;
1417 return blkdev_get(bdev, filp->f_mode, filp);
1420 static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
1422 int ret = 0;
1423 struct gendisk *disk = bdev->bd_disk;
1424 struct block_device *victim = NULL;
1426 mutex_lock_nested(&bdev->bd_mutex, for_part);
1427 if (for_part)
1428 bdev->bd_part_count--;
1430 if (!--bdev->bd_openers) {
1431 WARN_ON_ONCE(bdev->bd_holders);
1432 sync_blockdev(bdev);
1433 kill_bdev(bdev);
1434 /* ->release can cause the old bdi to disappear,
1435 * so must switch it out first
1437 bdev_inode_switch_bdi(bdev->bd_inode,
1438 &default_backing_dev_info);
1440 if (bdev->bd_contains == bdev) {
1441 if (disk->fops->release)
1442 ret = disk->fops->release(disk, mode);
1444 if (!bdev->bd_openers) {
1445 struct module *owner = disk->fops->owner;
1447 disk_put_part(bdev->bd_part);
1448 bdev->bd_part = NULL;
1449 bdev->bd_disk = NULL;
1450 if (bdev != bdev->bd_contains)
1451 victim = bdev->bd_contains;
1452 bdev->bd_contains = NULL;
1454 put_disk(disk);
1455 module_put(owner);
1457 mutex_unlock(&bdev->bd_mutex);
1458 bdput(bdev);
1459 if (victim)
1460 __blkdev_put(victim, mode, 1);
1461 return ret;
1464 int blkdev_put(struct block_device *bdev, fmode_t mode)
1466 mutex_lock(&bdev->bd_mutex);
1468 if (mode & FMODE_EXCL) {
1469 bool bdev_free;
1472 * Release a claim on the device. The holder fields
1473 * are protected with bdev_lock. bd_mutex is to
1474 * synchronize disk_holder unlinking.
1476 spin_lock(&bdev_lock);
1478 WARN_ON_ONCE(--bdev->bd_holders < 0);
1479 WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0);
1481 /* bd_contains might point to self, check in a separate step */
1482 if ((bdev_free = !bdev->bd_holders))
1483 bdev->bd_holder = NULL;
1484 if (!bdev->bd_contains->bd_holders)
1485 bdev->bd_contains->bd_holder = NULL;
1487 spin_unlock(&bdev_lock);
1490 * If this was the last claim, remove holder link and
1491 * unblock evpoll if it was a write holder.
1493 if (bdev_free && bdev->bd_write_holder) {
1494 disk_unblock_events(bdev->bd_disk);
1495 bdev->bd_write_holder = false;
1500 * Trigger event checking and tell drivers to flush MEDIA_CHANGE
1501 * event. This is to ensure detection of media removal commanded
1502 * from userland - e.g. eject(1).
1504 disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE);
1506 mutex_unlock(&bdev->bd_mutex);
1508 return __blkdev_put(bdev, mode, 0);
1510 EXPORT_SYMBOL(blkdev_put);
1512 static int blkdev_close(struct inode * inode, struct file * filp)
1514 struct block_device *bdev = I_BDEV(filp->f_mapping->host);
1516 return blkdev_put(bdev, filp->f_mode);
1519 static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
1521 struct block_device *bdev = I_BDEV(file->f_mapping->host);
1522 fmode_t mode = file->f_mode;
1525 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
1526 * to updated it before every ioctl.
1528 if (file->f_flags & O_NDELAY)
1529 mode |= FMODE_NDELAY;
1530 else
1531 mode &= ~FMODE_NDELAY;
1533 return blkdev_ioctl(bdev, mode, cmd, arg);
1537 * Write data to the block device. Only intended for the block device itself
1538 * and the raw driver which basically is a fake block device.
1540 * Does not take i_mutex for the write and thus is not for general purpose
1541 * use.
1543 ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
1544 unsigned long nr_segs, loff_t pos)
1546 struct file *file = iocb->ki_filp;
1547 ssize_t ret;
1549 BUG_ON(iocb->ki_pos != pos);
1551 ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
1552 if (ret > 0 || ret == -EIOCBQUEUED) {
1553 ssize_t err;
1555 err = generic_write_sync(file, pos, ret);
1556 if (err < 0 && ret > 0)
1557 ret = err;
1559 return ret;
1561 EXPORT_SYMBOL_GPL(blkdev_aio_write);
1564 * Try to release a page associated with block device when the system
1565 * is under memory pressure.
1567 static int blkdev_releasepage(struct page *page, gfp_t wait)
1569 struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;
1571 if (super && super->s_op->bdev_try_to_free_page)
1572 return super->s_op->bdev_try_to_free_page(super, page, wait);
1574 return try_to_free_buffers(page);
1577 static const struct address_space_operations def_blk_aops = {
1578 .readpage = blkdev_readpage,
1579 .writepage = blkdev_writepage,
1580 .write_begin = blkdev_write_begin,
1581 .write_end = blkdev_write_end,
1582 .writepages = generic_writepages,
1583 .releasepage = blkdev_releasepage,
1584 .direct_IO = blkdev_direct_IO,
1587 const struct file_operations def_blk_fops = {
1588 .open = blkdev_open,
1589 .release = blkdev_close,
1590 .llseek = block_llseek,
1591 .read = do_sync_read,
1592 .write = do_sync_write,
1593 .aio_read = generic_file_aio_read,
1594 .aio_write = blkdev_aio_write,
1595 .mmap = generic_file_mmap,
1596 .fsync = blkdev_fsync,
1597 .unlocked_ioctl = block_ioctl,
1598 #ifdef CONFIG_COMPAT
1599 .compat_ioctl = compat_blkdev_ioctl,
1600 #endif
1601 .splice_read = generic_file_splice_read,
1602 .splice_write = generic_file_splice_write,
1605 int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
1607 int res;
1608 mm_segment_t old_fs = get_fs();
1609 set_fs(KERNEL_DS);
1610 res = blkdev_ioctl(bdev, 0, cmd, arg);
1611 set_fs(old_fs);
1612 return res;
1615 EXPORT_SYMBOL(ioctl_by_bdev);
1618 * lookup_bdev - lookup a struct block_device by name
1619 * @pathname: special file representing the block device
1621 * Get a reference to the blockdevice at @pathname in the current
1622 * namespace if possible and return it. Return ERR_PTR(error)
1623 * otherwise.
1625 struct block_device *lookup_bdev(const char *pathname)
1627 struct block_device *bdev;
1628 struct inode *inode;
1629 struct path path;
1630 int error;
1632 if (!pathname || !*pathname)
1633 return ERR_PTR(-EINVAL);
1635 error = kern_path(pathname, LOOKUP_FOLLOW, &path);
1636 if (error)
1637 return ERR_PTR(error);
1639 inode = path.dentry->d_inode;
1640 error = -ENOTBLK;
1641 if (!S_ISBLK(inode->i_mode))
1642 goto fail;
1643 error = -EACCES;
1644 if (path.mnt->mnt_flags & MNT_NODEV)
1645 goto fail;
1646 error = -ENOMEM;
1647 bdev = bd_acquire(inode);
1648 if (!bdev)
1649 goto fail;
1650 out:
1651 path_put(&path);
1652 return bdev;
1653 fail:
1654 bdev = ERR_PTR(error);
1655 goto out;
1657 EXPORT_SYMBOL(lookup_bdev);
1659 int __invalidate_device(struct block_device *bdev, bool kill_dirty)
1661 struct super_block *sb = get_super(bdev);
1662 int res = 0;
1664 if (sb) {
1666 * no need to lock the super, get_super holds the
1667 * read mutex so the filesystem cannot go away
1668 * under us (->put_super runs with the write lock
1669 * hold).
1671 shrink_dcache_sb(sb);
1672 res = invalidate_inodes(sb, kill_dirty);
1673 drop_super(sb);
1675 invalidate_bdev(bdev);
1676 return res;
1678 EXPORT_SYMBOL(__invalidate_device);