4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
8 #include <linux/init.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/backing-dev.h>
18 #include <linux/module.h>
19 #include <linux/blkpg.h>
20 #include <linux/magic.h>
21 #include <linux/buffer_head.h>
22 #include <linux/swap.h>
23 #include <linux/pagevec.h>
24 #include <linux/writeback.h>
25 #include <linux/mpage.h>
26 #include <linux/mount.h>
27 #include <linux/uio.h>
28 #include <linux/namei.h>
29 #include <linux/log2.h>
30 #include <linux/cleancache.h>
31 #include <linux/dax.h>
32 #include <linux/badblocks.h>
33 #include <asm/uaccess.h>
37 struct block_device bdev;
38 struct inode vfs_inode;
41 static const struct address_space_operations def_blk_aops;
43 static inline struct bdev_inode *BDEV_I(struct inode *inode)
45 return container_of(inode, struct bdev_inode, vfs_inode);
48 struct block_device *I_BDEV(struct inode *inode)
50 return &BDEV_I(inode)->bdev;
52 EXPORT_SYMBOL(I_BDEV);
54 void __vfs_msg(struct super_block *sb, const char *prefix, const char *fmt, ...)
62 printk_ratelimited("%sVFS (%s): %pV\n", prefix, sb->s_id, &vaf);
66 static void bdev_write_inode(struct block_device *bdev)
68 struct inode *inode = bdev->bd_inode;
71 spin_lock(&inode->i_lock);
72 while (inode->i_state & I_DIRTY) {
73 spin_unlock(&inode->i_lock);
74 ret = write_inode_now(inode, true);
76 char name[BDEVNAME_SIZE];
77 pr_warn_ratelimited("VFS: Dirty inode writeback failed "
78 "for block device %s (err=%d).\n",
79 bdevname(bdev, name), ret);
81 spin_lock(&inode->i_lock);
83 spin_unlock(&inode->i_lock);
86 /* Kill _all_ buffers and pagecache , dirty or not.. */
87 void kill_bdev(struct block_device *bdev)
89 struct address_space *mapping = bdev->bd_inode->i_mapping;
91 if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
95 truncate_inode_pages(mapping, 0);
97 EXPORT_SYMBOL(kill_bdev);
99 /* Invalidate clean unused buffers and pagecache. */
100 void invalidate_bdev(struct block_device *bdev)
102 struct address_space *mapping = bdev->bd_inode->i_mapping;
104 if (mapping->nrpages == 0)
107 invalidate_bh_lrus();
108 lru_add_drain_all(); /* make sure all lru add caches are flushed */
109 invalidate_mapping_pages(mapping, 0, -1);
110 /* 99% of the time, we don't need to flush the cleancache on the bdev.
111 * But, for the strange corners, lets be cautious
113 cleancache_invalidate_inode(mapping);
115 EXPORT_SYMBOL(invalidate_bdev);
117 int set_blocksize(struct block_device *bdev, int size)
119 /* Size must be a power of two, and between 512 and PAGE_SIZE */
120 if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
123 /* Size cannot be smaller than the size supported by the device */
124 if (size < bdev_logical_block_size(bdev))
127 /* Don't change the size if it is same as current */
128 if (bdev->bd_block_size != size) {
130 bdev->bd_block_size = size;
131 bdev->bd_inode->i_blkbits = blksize_bits(size);
137 EXPORT_SYMBOL(set_blocksize);
139 int sb_set_blocksize(struct super_block *sb, int size)
141 if (set_blocksize(sb->s_bdev, size))
143 /* If we get here, we know size is power of two
144 * and it's value is between 512 and PAGE_SIZE */
145 sb->s_blocksize = size;
146 sb->s_blocksize_bits = blksize_bits(size);
147 return sb->s_blocksize;
150 EXPORT_SYMBOL(sb_set_blocksize);
152 int sb_min_blocksize(struct super_block *sb, int size)
154 int minsize = bdev_logical_block_size(sb->s_bdev);
157 return sb_set_blocksize(sb, size);
160 EXPORT_SYMBOL(sb_min_blocksize);
163 blkdev_get_block(struct inode *inode, sector_t iblock,
164 struct buffer_head *bh, int create)
166 bh->b_bdev = I_BDEV(inode);
167 bh->b_blocknr = iblock;
168 set_buffer_mapped(bh);
172 static struct inode *bdev_file_inode(struct file *file)
174 return file->f_mapping->host;
178 blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
180 struct file *file = iocb->ki_filp;
181 struct inode *inode = bdev_file_inode(file);
184 return dax_do_io(iocb, inode, iter, blkdev_get_block,
185 NULL, DIO_SKIP_DIO_COUNT);
186 return __blockdev_direct_IO(iocb, inode, I_BDEV(inode), iter,
187 blkdev_get_block, NULL, NULL,
191 int __sync_blockdev(struct block_device *bdev, int wait)
196 return filemap_flush(bdev->bd_inode->i_mapping);
197 return filemap_write_and_wait(bdev->bd_inode->i_mapping);
201 * Write out and wait upon all the dirty data associated with a block
202 * device via its mapping. Does not take the superblock lock.
204 int sync_blockdev(struct block_device *bdev)
206 return __sync_blockdev(bdev, 1);
208 EXPORT_SYMBOL(sync_blockdev);
211 * Write out and wait upon all dirty data associated with this
212 * device. Filesystem data as well as the underlying block
213 * device. Takes the superblock lock.
215 int fsync_bdev(struct block_device *bdev)
217 struct super_block *sb = get_super(bdev);
219 int res = sync_filesystem(sb);
223 return sync_blockdev(bdev);
225 EXPORT_SYMBOL(fsync_bdev);
228 * freeze_bdev -- lock a filesystem and force it into a consistent state
229 * @bdev: blockdevice to lock
231 * If a superblock is found on this device, we take the s_umount semaphore
232 * on it to make sure nobody unmounts until the snapshot creation is done.
233 * The reference counter (bd_fsfreeze_count) guarantees that only the last
234 * unfreeze process can unfreeze the frozen filesystem actually when multiple
235 * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
236 * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
239 struct super_block *freeze_bdev(struct block_device *bdev)
241 struct super_block *sb;
244 mutex_lock(&bdev->bd_fsfreeze_mutex);
245 if (++bdev->bd_fsfreeze_count > 1) {
247 * We don't even need to grab a reference - the first call
248 * to freeze_bdev grab an active reference and only the last
249 * thaw_bdev drops it.
251 sb = get_super(bdev);
253 mutex_unlock(&bdev->bd_fsfreeze_mutex);
257 sb = get_active_super(bdev);
260 if (sb->s_op->freeze_super)
261 error = sb->s_op->freeze_super(sb);
263 error = freeze_super(sb);
265 deactivate_super(sb);
266 bdev->bd_fsfreeze_count--;
267 mutex_unlock(&bdev->bd_fsfreeze_mutex);
268 return ERR_PTR(error);
270 deactivate_super(sb);
273 mutex_unlock(&bdev->bd_fsfreeze_mutex);
274 return sb; /* thaw_bdev releases s->s_umount */
276 EXPORT_SYMBOL(freeze_bdev);
279 * thaw_bdev -- unlock filesystem
280 * @bdev: blockdevice to unlock
281 * @sb: associated superblock
283 * Unlocks the filesystem and marks it writeable again after freeze_bdev().
285 int thaw_bdev(struct block_device *bdev, struct super_block *sb)
289 mutex_lock(&bdev->bd_fsfreeze_mutex);
290 if (!bdev->bd_fsfreeze_count)
294 if (--bdev->bd_fsfreeze_count > 0)
300 if (sb->s_op->thaw_super)
301 error = sb->s_op->thaw_super(sb);
303 error = thaw_super(sb);
305 bdev->bd_fsfreeze_count++;
306 mutex_unlock(&bdev->bd_fsfreeze_mutex);
310 mutex_unlock(&bdev->bd_fsfreeze_mutex);
313 EXPORT_SYMBOL(thaw_bdev);
315 static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
317 return block_write_full_page(page, blkdev_get_block, wbc);
320 static int blkdev_readpage(struct file * file, struct page * page)
322 return block_read_full_page(page, blkdev_get_block);
325 static int blkdev_readpages(struct file *file, struct address_space *mapping,
326 struct list_head *pages, unsigned nr_pages)
328 return mpage_readpages(mapping, pages, nr_pages, blkdev_get_block);
331 static int blkdev_write_begin(struct file *file, struct address_space *mapping,
332 loff_t pos, unsigned len, unsigned flags,
333 struct page **pagep, void **fsdata)
335 return block_write_begin(mapping, pos, len, flags, pagep,
339 static int blkdev_write_end(struct file *file, struct address_space *mapping,
340 loff_t pos, unsigned len, unsigned copied,
341 struct page *page, void *fsdata)
344 ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
354 * for a block special file file_inode(file)->i_size is zero
355 * so we compute the size by hand (just as in block_read/write above)
357 static loff_t block_llseek(struct file *file, loff_t offset, int whence)
359 struct inode *bd_inode = bdev_file_inode(file);
362 inode_lock(bd_inode);
363 retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
364 inode_unlock(bd_inode);
368 int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
370 struct inode *bd_inode = bdev_file_inode(filp);
371 struct block_device *bdev = I_BDEV(bd_inode);
374 error = filemap_write_and_wait_range(filp->f_mapping, start, end);
379 * There is no need to serialise calls to blkdev_issue_flush with
380 * i_mutex and doing so causes performance issues with concurrent
381 * O_SYNC writers to a block device.
383 error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL);
384 if (error == -EOPNOTSUPP)
389 EXPORT_SYMBOL(blkdev_fsync);
392 * bdev_read_page() - Start reading a page from a block device
393 * @bdev: The device to read the page from
394 * @sector: The offset on the device to read the page to (need not be aligned)
395 * @page: The page to read
397 * On entry, the page should be locked. It will be unlocked when the page
398 * has been read. If the block driver implements rw_page synchronously,
399 * that will be true on exit from this function, but it need not be.
401 * Errors returned by this function are usually "soft", eg out of memory, or
402 * queue full; callers should try a different route to read this page rather
403 * than propagate an error back up the stack.
405 * Return: negative errno if an error occurs, 0 if submission was successful.
407 int bdev_read_page(struct block_device *bdev, sector_t sector,
410 const struct block_device_operations *ops = bdev->bd_disk->fops;
411 int result = -EOPNOTSUPP;
413 if (!ops->rw_page || bdev_get_integrity(bdev))
416 result = blk_queue_enter(bdev->bd_queue, false);
419 result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
421 blk_queue_exit(bdev->bd_queue);
424 EXPORT_SYMBOL_GPL(bdev_read_page);
427 * bdev_write_page() - Start writing a page to a block device
428 * @bdev: The device to write the page to
429 * @sector: The offset on the device to write the page to (need not be aligned)
430 * @page: The page to write
431 * @wbc: The writeback_control for the write
433 * On entry, the page should be locked and not currently under writeback.
434 * On exit, if the write started successfully, the page will be unlocked and
435 * under writeback. If the write failed already (eg the driver failed to
436 * queue the page to the device), the page will still be locked. If the
437 * caller is a ->writepage implementation, it will need to unlock the page.
439 * Errors returned by this function are usually "soft", eg out of memory, or
440 * queue full; callers should try a different route to write this page rather
441 * than propagate an error back up the stack.
443 * Return: negative errno if an error occurs, 0 if submission was successful.
445 int bdev_write_page(struct block_device *bdev, sector_t sector,
446 struct page *page, struct writeback_control *wbc)
449 const struct block_device_operations *ops = bdev->bd_disk->fops;
451 if (!ops->rw_page || bdev_get_integrity(bdev))
453 result = blk_queue_enter(bdev->bd_queue, false);
457 set_page_writeback(page);
458 result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
461 end_page_writeback(page);
464 blk_queue_exit(bdev->bd_queue);
467 EXPORT_SYMBOL_GPL(bdev_write_page);
470 * bdev_direct_access() - Get the address for directly-accessibly memory
471 * @bdev: The device containing the memory
472 * @dax: control and output parameters for ->direct_access
474 * If a block device is made up of directly addressable memory, this function
475 * will tell the caller the PFN and the address of the memory. The address
476 * may be directly dereferenced within the kernel without the need to call
477 * ioremap(), kmap() or similar. The PFN is suitable for inserting into
480 * Return: negative errno if an error occurs, otherwise the number of bytes
481 * accessible at this address.
483 long bdev_direct_access(struct block_device *bdev, struct blk_dax_ctl *dax)
485 sector_t sector = dax->sector;
486 long avail, size = dax->size;
487 const struct block_device_operations *ops = bdev->bd_disk->fops;
490 * The device driver is allowed to sleep, in order to make the
491 * memory directly accessible.
497 if (!blk_queue_dax(bdev_get_queue(bdev)) || !ops->direct_access)
499 if ((sector + DIV_ROUND_UP(size, 512)) >
500 part_nr_sects_read(bdev->bd_part))
502 sector += get_start_sect(bdev);
503 if (sector % (PAGE_SIZE / 512))
505 avail = ops->direct_access(bdev, sector, &dax->addr, &dax->pfn, size);
508 if (avail > 0 && avail & ~PAGE_MASK)
510 return min(avail, size);
512 EXPORT_SYMBOL_GPL(bdev_direct_access);
515 * bdev_dax_supported() - Check if the device supports dax for filesystem
516 * @sb: The superblock of the device
517 * @blocksize: The block size of the device
519 * This is a library function for filesystems to check if the block device
520 * can be mounted with dax option.
522 * Return: negative errno if unsupported, 0 if supported.
524 int bdev_dax_supported(struct super_block *sb, int blocksize)
526 struct blk_dax_ctl dax = {
532 if (blocksize != PAGE_SIZE) {
533 vfs_msg(sb, KERN_ERR, "error: unsupported blocksize for dax");
537 err = bdev_direct_access(sb->s_bdev, &dax);
541 vfs_msg(sb, KERN_ERR,
542 "error: device does not support dax");
545 vfs_msg(sb, KERN_ERR,
546 "error: unaligned partition for dax");
549 vfs_msg(sb, KERN_ERR,
550 "error: dax access failed (%d)", err);
557 EXPORT_SYMBOL_GPL(bdev_dax_supported);
560 * bdev_dax_capable() - Return if the raw device is capable for dax
561 * @bdev: The device for raw block device access
563 bool bdev_dax_capable(struct block_device *bdev)
565 struct blk_dax_ctl dax = {
569 if (!IS_ENABLED(CONFIG_FS_DAX))
573 if (bdev_direct_access(bdev, &dax) < 0)
576 dax.sector = bdev->bd_part->nr_sects - (PAGE_SIZE / 512);
577 if (bdev_direct_access(bdev, &dax) < 0)
587 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
588 static struct kmem_cache * bdev_cachep __read_mostly;
590 static struct inode *bdev_alloc_inode(struct super_block *sb)
592 struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
595 return &ei->vfs_inode;
598 static void bdev_i_callback(struct rcu_head *head)
600 struct inode *inode = container_of(head, struct inode, i_rcu);
601 struct bdev_inode *bdi = BDEV_I(inode);
603 kmem_cache_free(bdev_cachep, bdi);
606 static void bdev_destroy_inode(struct inode *inode)
608 call_rcu(&inode->i_rcu, bdev_i_callback);
611 static void init_once(void *foo)
613 struct bdev_inode *ei = (struct bdev_inode *) foo;
614 struct block_device *bdev = &ei->bdev;
616 memset(bdev, 0, sizeof(*bdev));
617 mutex_init(&bdev->bd_mutex);
618 INIT_LIST_HEAD(&bdev->bd_list);
620 INIT_LIST_HEAD(&bdev->bd_holder_disks);
622 inode_init_once(&ei->vfs_inode);
623 /* Initialize mutex for freeze. */
624 mutex_init(&bdev->bd_fsfreeze_mutex);
627 static void bdev_evict_inode(struct inode *inode)
629 struct block_device *bdev = &BDEV_I(inode)->bdev;
630 truncate_inode_pages_final(&inode->i_data);
631 invalidate_inode_buffers(inode); /* is it needed here? */
633 spin_lock(&bdev_lock);
634 list_del_init(&bdev->bd_list);
635 spin_unlock(&bdev_lock);
638 static const struct super_operations bdev_sops = {
639 .statfs = simple_statfs,
640 .alloc_inode = bdev_alloc_inode,
641 .destroy_inode = bdev_destroy_inode,
642 .drop_inode = generic_delete_inode,
643 .evict_inode = bdev_evict_inode,
646 static struct dentry *bd_mount(struct file_system_type *fs_type,
647 int flags, const char *dev_name, void *data)
650 dent = mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC);
652 dent->d_sb->s_iflags |= SB_I_CGROUPWB;
656 static struct file_system_type bd_type = {
659 .kill_sb = kill_anon_super,
662 struct super_block *blockdev_superblock __read_mostly;
663 EXPORT_SYMBOL_GPL(blockdev_superblock);
665 void __init bdev_cache_init(void)
668 static struct vfsmount *bd_mnt;
670 bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
671 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
672 SLAB_MEM_SPREAD|SLAB_ACCOUNT|SLAB_PANIC),
674 err = register_filesystem(&bd_type);
676 panic("Cannot register bdev pseudo-fs");
677 bd_mnt = kern_mount(&bd_type);
679 panic("Cannot create bdev pseudo-fs");
680 blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */
684 * Most likely _very_ bad one - but then it's hardly critical for small
685 * /dev and can be fixed when somebody will need really large one.
686 * Keep in mind that it will be fed through icache hash function too.
688 static inline unsigned long hash(dev_t dev)
690 return MAJOR(dev)+MINOR(dev);
693 static int bdev_test(struct inode *inode, void *data)
695 return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
698 static int bdev_set(struct inode *inode, void *data)
700 BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
704 static LIST_HEAD(all_bdevs);
706 struct block_device *bdget(dev_t dev)
708 struct block_device *bdev;
711 inode = iget5_locked(blockdev_superblock, hash(dev),
712 bdev_test, bdev_set, &dev);
717 bdev = &BDEV_I(inode)->bdev;
719 if (inode->i_state & I_NEW) {
720 bdev->bd_contains = NULL;
721 bdev->bd_super = NULL;
722 bdev->bd_inode = inode;
723 bdev->bd_block_size = (1 << inode->i_blkbits);
724 bdev->bd_part_count = 0;
725 bdev->bd_invalidated = 0;
726 inode->i_mode = S_IFBLK;
728 inode->i_bdev = bdev;
729 inode->i_data.a_ops = &def_blk_aops;
730 mapping_set_gfp_mask(&inode->i_data, GFP_USER);
731 spin_lock(&bdev_lock);
732 list_add(&bdev->bd_list, &all_bdevs);
733 spin_unlock(&bdev_lock);
734 unlock_new_inode(inode);
739 EXPORT_SYMBOL(bdget);
742 * bdgrab -- Grab a reference to an already referenced block device
743 * @bdev: Block device to grab a reference to.
745 struct block_device *bdgrab(struct block_device *bdev)
747 ihold(bdev->bd_inode);
750 EXPORT_SYMBOL(bdgrab);
752 long nr_blockdev_pages(void)
754 struct block_device *bdev;
756 spin_lock(&bdev_lock);
757 list_for_each_entry(bdev, &all_bdevs, bd_list) {
758 ret += bdev->bd_inode->i_mapping->nrpages;
760 spin_unlock(&bdev_lock);
764 void bdput(struct block_device *bdev)
766 iput(bdev->bd_inode);
769 EXPORT_SYMBOL(bdput);
771 static struct block_device *bd_acquire(struct inode *inode)
773 struct block_device *bdev;
775 spin_lock(&bdev_lock);
776 bdev = inode->i_bdev;
779 spin_unlock(&bdev_lock);
782 spin_unlock(&bdev_lock);
784 bdev = bdget(inode->i_rdev);
786 spin_lock(&bdev_lock);
787 if (!inode->i_bdev) {
789 * We take an additional reference to bd_inode,
790 * and it's released in clear_inode() of inode.
791 * So, we can access it via ->i_mapping always
795 inode->i_bdev = bdev;
796 inode->i_mapping = bdev->bd_inode->i_mapping;
798 spin_unlock(&bdev_lock);
803 /* Call when you free inode */
805 void bd_forget(struct inode *inode)
807 struct block_device *bdev = NULL;
809 spin_lock(&bdev_lock);
810 if (!sb_is_blkdev_sb(inode->i_sb))
811 bdev = inode->i_bdev;
812 inode->i_bdev = NULL;
813 inode->i_mapping = &inode->i_data;
814 spin_unlock(&bdev_lock);
821 * bd_may_claim - test whether a block device can be claimed
822 * @bdev: block device of interest
823 * @whole: whole block device containing @bdev, may equal @bdev
824 * @holder: holder trying to claim @bdev
826 * Test whether @bdev can be claimed by @holder.
829 * spin_lock(&bdev_lock).
832 * %true if @bdev can be claimed, %false otherwise.
834 static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
837 if (bdev->bd_holder == holder)
838 return true; /* already a holder */
839 else if (bdev->bd_holder != NULL)
840 return false; /* held by someone else */
841 else if (bdev->bd_contains == bdev)
842 return true; /* is a whole device which isn't held */
844 else if (whole->bd_holder == bd_may_claim)
845 return true; /* is a partition of a device that is being partitioned */
846 else if (whole->bd_holder != NULL)
847 return false; /* is a partition of a held device */
849 return true; /* is a partition of an un-held device */
853 * bd_prepare_to_claim - prepare to claim a block device
854 * @bdev: block device of interest
855 * @whole: the whole device containing @bdev, may equal @bdev
856 * @holder: holder trying to claim @bdev
858 * Prepare to claim @bdev. This function fails if @bdev is already
859 * claimed by another holder and waits if another claiming is in
860 * progress. This function doesn't actually claim. On successful
861 * return, the caller has ownership of bd_claiming and bd_holder[s].
864 * spin_lock(&bdev_lock). Might release bdev_lock, sleep and regrab
868 * 0 if @bdev can be claimed, -EBUSY otherwise.
870 static int bd_prepare_to_claim(struct block_device *bdev,
871 struct block_device *whole, void *holder)
874 /* if someone else claimed, fail */
875 if (!bd_may_claim(bdev, whole, holder))
878 /* if claiming is already in progress, wait for it to finish */
879 if (whole->bd_claiming) {
880 wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
883 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
884 spin_unlock(&bdev_lock);
886 finish_wait(wq, &wait);
887 spin_lock(&bdev_lock);
896 * bd_start_claiming - start claiming a block device
897 * @bdev: block device of interest
898 * @holder: holder trying to claim @bdev
900 * @bdev is about to be opened exclusively. Check @bdev can be opened
901 * exclusively and mark that an exclusive open is in progress. Each
902 * successful call to this function must be matched with a call to
903 * either bd_finish_claiming() or bd_abort_claiming() (which do not
906 * This function is used to gain exclusive access to the block device
907 * without actually causing other exclusive open attempts to fail. It
908 * should be used when the open sequence itself requires exclusive
909 * access but may subsequently fail.
915 * Pointer to the block device containing @bdev on success, ERR_PTR()
918 static struct block_device *bd_start_claiming(struct block_device *bdev,
921 struct gendisk *disk;
922 struct block_device *whole;
928 * @bdev might not have been initialized properly yet, look up
929 * and grab the outer block device the hard way.
931 disk = get_gendisk(bdev->bd_dev, &partno);
933 return ERR_PTR(-ENXIO);
936 * Normally, @bdev should equal what's returned from bdget_disk()
937 * if partno is 0; however, some drivers (floppy) use multiple
938 * bdev's for the same physical device and @bdev may be one of the
939 * aliases. Keep @bdev if partno is 0. This means claimer
940 * tracking is broken for those devices but it has always been that
944 whole = bdget_disk(disk, 0);
946 whole = bdgrab(bdev);
948 module_put(disk->fops->owner);
951 return ERR_PTR(-ENOMEM);
953 /* prepare to claim, if successful, mark claiming in progress */
954 spin_lock(&bdev_lock);
956 err = bd_prepare_to_claim(bdev, whole, holder);
958 whole->bd_claiming = holder;
959 spin_unlock(&bdev_lock);
962 spin_unlock(&bdev_lock);
969 struct bd_holder_disk {
970 struct list_head list;
971 struct gendisk *disk;
975 static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
976 struct gendisk *disk)
978 struct bd_holder_disk *holder;
980 list_for_each_entry(holder, &bdev->bd_holder_disks, list)
981 if (holder->disk == disk)
986 static int add_symlink(struct kobject *from, struct kobject *to)
988 return sysfs_create_link(from, to, kobject_name(to));
991 static void del_symlink(struct kobject *from, struct kobject *to)
993 sysfs_remove_link(from, kobject_name(to));
997 * bd_link_disk_holder - create symlinks between holding disk and slave bdev
998 * @bdev: the claimed slave bdev
999 * @disk: the holding disk
1001 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
1003 * This functions creates the following sysfs symlinks.
1005 * - from "slaves" directory of the holder @disk to the claimed @bdev
1006 * - from "holders" directory of the @bdev to the holder @disk
1008 * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
1009 * passed to bd_link_disk_holder(), then:
1011 * /sys/block/dm-0/slaves/sda --> /sys/block/sda
1012 * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
1014 * The caller must have claimed @bdev before calling this function and
1015 * ensure that both @bdev and @disk are valid during the creation and
1016 * lifetime of these symlinks.
1022 * 0 on success, -errno on failure.
1024 int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
1026 struct bd_holder_disk *holder;
1029 mutex_lock(&bdev->bd_mutex);
1031 WARN_ON_ONCE(!bdev->bd_holder);
1033 /* FIXME: remove the following once add_disk() handles errors */
1034 if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
1037 holder = bd_find_holder_disk(bdev, disk);
1043 holder = kzalloc(sizeof(*holder), GFP_KERNEL);
1049 INIT_LIST_HEAD(&holder->list);
1050 holder->disk = disk;
1053 ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
1057 ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
1061 * bdev could be deleted beneath us which would implicitly destroy
1062 * the holder directory. Hold on to it.
1064 kobject_get(bdev->bd_part->holder_dir);
1066 list_add(&holder->list, &bdev->bd_holder_disks);
1070 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
1074 mutex_unlock(&bdev->bd_mutex);
1077 EXPORT_SYMBOL_GPL(bd_link_disk_holder);
1080 * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
1081 * @bdev: the calimed slave bdev
1082 * @disk: the holding disk
1084 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
1089 void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
1091 struct bd_holder_disk *holder;
1093 mutex_lock(&bdev->bd_mutex);
1095 holder = bd_find_holder_disk(bdev, disk);
1097 if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
1098 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
1099 del_symlink(bdev->bd_part->holder_dir,
1100 &disk_to_dev(disk)->kobj);
1101 kobject_put(bdev->bd_part->holder_dir);
1102 list_del_init(&holder->list);
1106 mutex_unlock(&bdev->bd_mutex);
1108 EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
1112 * flush_disk - invalidates all buffer-cache entries on a disk
1114 * @bdev: struct block device to be flushed
1115 * @kill_dirty: flag to guide handling of dirty inodes
1117 * Invalidates all buffer-cache entries on a disk. It should be called
1118 * when a disk has been changed -- either by a media change or online
1121 static void flush_disk(struct block_device *bdev, bool kill_dirty)
1123 if (__invalidate_device(bdev, kill_dirty)) {
1124 printk(KERN_WARNING "VFS: busy inodes on changed media or "
1125 "resized disk %s\n",
1126 bdev->bd_disk ? bdev->bd_disk->disk_name : "");
1131 if (disk_part_scan_enabled(bdev->bd_disk))
1132 bdev->bd_invalidated = 1;
1136 * check_disk_size_change - checks for disk size change and adjusts bdev size.
1137 * @disk: struct gendisk to check
1138 * @bdev: struct bdev to adjust.
1140 * This routine checks to see if the bdev size does not match the disk size
1141 * and adjusts it if it differs.
1143 void check_disk_size_change(struct gendisk *disk, struct block_device *bdev)
1145 loff_t disk_size, bdev_size;
1147 disk_size = (loff_t)get_capacity(disk) << 9;
1148 bdev_size = i_size_read(bdev->bd_inode);
1149 if (disk_size != bdev_size) {
1151 "%s: detected capacity change from %lld to %lld\n",
1152 disk->disk_name, bdev_size, disk_size);
1153 i_size_write(bdev->bd_inode, disk_size);
1154 flush_disk(bdev, false);
1157 EXPORT_SYMBOL(check_disk_size_change);
1160 * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
1161 * @disk: struct gendisk to be revalidated
1163 * This routine is a wrapper for lower-level driver's revalidate_disk
1164 * call-backs. It is used to do common pre and post operations needed
1165 * for all revalidate_disk operations.
1167 int revalidate_disk(struct gendisk *disk)
1169 struct block_device *bdev;
1172 if (disk->fops->revalidate_disk)
1173 ret = disk->fops->revalidate_disk(disk);
1174 blk_integrity_revalidate(disk);
1175 bdev = bdget_disk(disk, 0);
1179 mutex_lock(&bdev->bd_mutex);
1180 check_disk_size_change(disk, bdev);
1181 bdev->bd_invalidated = 0;
1182 mutex_unlock(&bdev->bd_mutex);
1186 EXPORT_SYMBOL(revalidate_disk);
1189 * This routine checks whether a removable media has been changed,
1190 * and invalidates all buffer-cache-entries in that case. This
1191 * is a relatively slow routine, so we have to try to minimize using
1192 * it. Thus it is called only upon a 'mount' or 'open'. This
1193 * is the best way of combining speed and utility, I think.
1194 * People changing diskettes in the middle of an operation deserve
1197 int check_disk_change(struct block_device *bdev)
1199 struct gendisk *disk = bdev->bd_disk;
1200 const struct block_device_operations *bdops = disk->fops;
1201 unsigned int events;
1203 events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
1204 DISK_EVENT_EJECT_REQUEST);
1205 if (!(events & DISK_EVENT_MEDIA_CHANGE))
1208 flush_disk(bdev, true);
1209 if (bdops->revalidate_disk)
1210 bdops->revalidate_disk(bdev->bd_disk);
1214 EXPORT_SYMBOL(check_disk_change);
1216 void bd_set_size(struct block_device *bdev, loff_t size)
1218 unsigned bsize = bdev_logical_block_size(bdev);
1220 inode_lock(bdev->bd_inode);
1221 i_size_write(bdev->bd_inode, size);
1222 inode_unlock(bdev->bd_inode);
1223 while (bsize < PAGE_SIZE) {
1228 bdev->bd_block_size = bsize;
1229 bdev->bd_inode->i_blkbits = blksize_bits(bsize);
1231 EXPORT_SYMBOL(bd_set_size);
1233 static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
1238 * mutex_lock(part->bd_mutex)
1239 * mutex_lock_nested(whole->bd_mutex, 1)
1242 static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
1244 struct gendisk *disk;
1245 struct module *owner;
1250 if (mode & FMODE_READ)
1252 if (mode & FMODE_WRITE)
1255 * hooks: /n/, see "layering violations".
1258 ret = devcgroup_inode_permission(bdev->bd_inode, perm);
1268 disk = get_gendisk(bdev->bd_dev, &partno);
1271 owner = disk->fops->owner;
1273 disk_block_events(disk);
1274 mutex_lock_nested(&bdev->bd_mutex, for_part);
1275 if (!bdev->bd_openers) {
1276 bdev->bd_disk = disk;
1277 bdev->bd_queue = disk->queue;
1278 bdev->bd_contains = bdev;
1279 bdev->bd_inode->i_flags = 0;
1283 bdev->bd_part = disk_get_part(disk, partno);
1288 if (disk->fops->open) {
1289 ret = disk->fops->open(bdev, mode);
1290 if (ret == -ERESTARTSYS) {
1291 /* Lost a race with 'disk' being
1292 * deleted, try again.
1295 disk_put_part(bdev->bd_part);
1296 bdev->bd_part = NULL;
1297 bdev->bd_disk = NULL;
1298 bdev->bd_queue = NULL;
1299 mutex_unlock(&bdev->bd_mutex);
1300 disk_unblock_events(disk);
1308 bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
1309 if (!bdev_dax_capable(bdev))
1310 bdev->bd_inode->i_flags &= ~S_DAX;
1314 * If the device is invalidated, rescan partition
1315 * if open succeeded or failed with -ENOMEDIUM.
1316 * The latter is necessary to prevent ghost
1317 * partitions on a removed medium.
1319 if (bdev->bd_invalidated) {
1321 rescan_partitions(disk, bdev);
1322 else if (ret == -ENOMEDIUM)
1323 invalidate_partitions(disk, bdev);
1329 struct block_device *whole;
1330 whole = bdget_disk(disk, 0);
1335 ret = __blkdev_get(whole, mode, 1);
1338 bdev->bd_contains = whole;
1339 bdev->bd_part = disk_get_part(disk, partno);
1340 if (!(disk->flags & GENHD_FL_UP) ||
1341 !bdev->bd_part || !bdev->bd_part->nr_sects) {
1345 bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
1346 if (!bdev_dax_capable(bdev))
1347 bdev->bd_inode->i_flags &= ~S_DAX;
1350 if (bdev->bd_contains == bdev) {
1352 if (bdev->bd_disk->fops->open)
1353 ret = bdev->bd_disk->fops->open(bdev, mode);
1354 /* the same as first opener case, read comment there */
1355 if (bdev->bd_invalidated) {
1357 rescan_partitions(bdev->bd_disk, bdev);
1358 else if (ret == -ENOMEDIUM)
1359 invalidate_partitions(bdev->bd_disk, bdev);
1362 goto out_unlock_bdev;
1364 /* only one opener holds refs to the module and disk */
1370 bdev->bd_part_count++;
1371 mutex_unlock(&bdev->bd_mutex);
1372 disk_unblock_events(disk);
1376 disk_put_part(bdev->bd_part);
1377 bdev->bd_disk = NULL;
1378 bdev->bd_part = NULL;
1379 bdev->bd_queue = NULL;
1380 if (bdev != bdev->bd_contains)
1381 __blkdev_put(bdev->bd_contains, mode, 1);
1382 bdev->bd_contains = NULL;
1384 mutex_unlock(&bdev->bd_mutex);
1385 disk_unblock_events(disk);
1395 * blkdev_get - open a block device
1396 * @bdev: block_device to open
1397 * @mode: FMODE_* mask
1398 * @holder: exclusive holder identifier
1400 * Open @bdev with @mode. If @mode includes %FMODE_EXCL, @bdev is
1401 * open with exclusive access. Specifying %FMODE_EXCL with %NULL
1402 * @holder is invalid. Exclusive opens may nest for the same @holder.
1404 * On success, the reference count of @bdev is unchanged. On failure,
1411 * 0 on success, -errno on failure.
1413 int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
1415 struct block_device *whole = NULL;
1418 WARN_ON_ONCE((mode & FMODE_EXCL) && !holder);
1420 if ((mode & FMODE_EXCL) && holder) {
1421 whole = bd_start_claiming(bdev, holder);
1422 if (IS_ERR(whole)) {
1424 return PTR_ERR(whole);
1428 res = __blkdev_get(bdev, mode, 0);
1431 struct gendisk *disk = whole->bd_disk;
1433 /* finish claiming */
1434 mutex_lock(&bdev->bd_mutex);
1435 spin_lock(&bdev_lock);
1438 BUG_ON(!bd_may_claim(bdev, whole, holder));
1440 * Note that for a whole device bd_holders
1441 * will be incremented twice, and bd_holder
1442 * will be set to bd_may_claim before being
1445 whole->bd_holders++;
1446 whole->bd_holder = bd_may_claim;
1448 bdev->bd_holder = holder;
1451 /* tell others that we're done */
1452 BUG_ON(whole->bd_claiming != holder);
1453 whole->bd_claiming = NULL;
1454 wake_up_bit(&whole->bd_claiming, 0);
1456 spin_unlock(&bdev_lock);
1459 * Block event polling for write claims if requested. Any
1460 * write holder makes the write_holder state stick until
1461 * all are released. This is good enough and tracking
1462 * individual writeable reference is too fragile given the
1463 * way @mode is used in blkdev_get/put().
1465 if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder &&
1466 (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
1467 bdev->bd_write_holder = true;
1468 disk_block_events(disk);
1471 mutex_unlock(&bdev->bd_mutex);
1477 EXPORT_SYMBOL(blkdev_get);
1480 * blkdev_get_by_path - open a block device by name
1481 * @path: path to the block device to open
1482 * @mode: FMODE_* mask
1483 * @holder: exclusive holder identifier
1485 * Open the blockdevice described by the device file at @path. @mode
1486 * and @holder are identical to blkdev_get().
1488 * On success, the returned block_device has reference count of one.
1494 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1496 struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
1499 struct block_device *bdev;
1502 bdev = lookup_bdev(path);
1506 err = blkdev_get(bdev, mode, holder);
1508 return ERR_PTR(err);
1510 if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) {
1511 blkdev_put(bdev, mode);
1512 return ERR_PTR(-EACCES);
1517 EXPORT_SYMBOL(blkdev_get_by_path);
1520 * blkdev_get_by_dev - open a block device by device number
1521 * @dev: device number of block device to open
1522 * @mode: FMODE_* mask
1523 * @holder: exclusive holder identifier
1525 * Open the blockdevice described by device number @dev. @mode and
1526 * @holder are identical to blkdev_get().
1528 * Use it ONLY if you really do not have anything better - i.e. when
1529 * you are behind a truly sucky interface and all you are given is a
1530 * device number. _Never_ to be used for internal purposes. If you
1531 * ever need it - reconsider your API.
1533 * On success, the returned block_device has reference count of one.
1539 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1541 struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
1543 struct block_device *bdev;
1548 return ERR_PTR(-ENOMEM);
1550 err = blkdev_get(bdev, mode, holder);
1552 return ERR_PTR(err);
1556 EXPORT_SYMBOL(blkdev_get_by_dev);
1558 static int blkdev_open(struct inode * inode, struct file * filp)
1560 struct block_device *bdev;
1563 * Preserve backwards compatibility and allow large file access
1564 * even if userspace doesn't ask for it explicitly. Some mkfs
1565 * binary needs it. We might want to drop this workaround
1566 * during an unstable branch.
1568 filp->f_flags |= O_LARGEFILE;
1570 if (filp->f_flags & O_NDELAY)
1571 filp->f_mode |= FMODE_NDELAY;
1572 if (filp->f_flags & O_EXCL)
1573 filp->f_mode |= FMODE_EXCL;
1574 if ((filp->f_flags & O_ACCMODE) == 3)
1575 filp->f_mode |= FMODE_WRITE_IOCTL;
1577 bdev = bd_acquire(inode);
1581 filp->f_mapping = bdev->bd_inode->i_mapping;
1583 return blkdev_get(bdev, filp->f_mode, filp);
1586 static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
1588 struct gendisk *disk = bdev->bd_disk;
1589 struct block_device *victim = NULL;
1591 mutex_lock_nested(&bdev->bd_mutex, for_part);
1593 bdev->bd_part_count--;
1595 if (!--bdev->bd_openers) {
1596 WARN_ON_ONCE(bdev->bd_holders);
1597 sync_blockdev(bdev);
1600 bdev_write_inode(bdev);
1602 * Detaching bdev inode from its wb in __destroy_inode()
1603 * is too late: the queue which embeds its bdi (along with
1604 * root wb) can be gone as soon as we put_disk() below.
1606 inode_detach_wb(bdev->bd_inode);
1608 if (bdev->bd_contains == bdev) {
1609 if (disk->fops->release)
1610 disk->fops->release(disk, mode);
1612 if (!bdev->bd_openers) {
1613 struct module *owner = disk->fops->owner;
1615 disk_put_part(bdev->bd_part);
1616 bdev->bd_part = NULL;
1617 bdev->bd_disk = NULL;
1618 if (bdev != bdev->bd_contains)
1619 victim = bdev->bd_contains;
1620 bdev->bd_contains = NULL;
1625 mutex_unlock(&bdev->bd_mutex);
1628 __blkdev_put(victim, mode, 1);
1631 void blkdev_put(struct block_device *bdev, fmode_t mode)
1633 mutex_lock(&bdev->bd_mutex);
1635 if (mode & FMODE_EXCL) {
1639 * Release a claim on the device. The holder fields
1640 * are protected with bdev_lock. bd_mutex is to
1641 * synchronize disk_holder unlinking.
1643 spin_lock(&bdev_lock);
1645 WARN_ON_ONCE(--bdev->bd_holders < 0);
1646 WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0);
1648 /* bd_contains might point to self, check in a separate step */
1649 if ((bdev_free = !bdev->bd_holders))
1650 bdev->bd_holder = NULL;
1651 if (!bdev->bd_contains->bd_holders)
1652 bdev->bd_contains->bd_holder = NULL;
1654 spin_unlock(&bdev_lock);
1657 * If this was the last claim, remove holder link and
1658 * unblock evpoll if it was a write holder.
1660 if (bdev_free && bdev->bd_write_holder) {
1661 disk_unblock_events(bdev->bd_disk);
1662 bdev->bd_write_holder = false;
1667 * Trigger event checking and tell drivers to flush MEDIA_CHANGE
1668 * event. This is to ensure detection of media removal commanded
1669 * from userland - e.g. eject(1).
1671 disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE);
1673 mutex_unlock(&bdev->bd_mutex);
1675 __blkdev_put(bdev, mode, 0);
1677 EXPORT_SYMBOL(blkdev_put);
1679 static int blkdev_close(struct inode * inode, struct file * filp)
1681 struct block_device *bdev = I_BDEV(bdev_file_inode(filp));
1682 blkdev_put(bdev, filp->f_mode);
1686 static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
1688 struct block_device *bdev = I_BDEV(bdev_file_inode(file));
1689 fmode_t mode = file->f_mode;
1692 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
1693 * to updated it before every ioctl.
1695 if (file->f_flags & O_NDELAY)
1696 mode |= FMODE_NDELAY;
1698 mode &= ~FMODE_NDELAY;
1700 return blkdev_ioctl(bdev, mode, cmd, arg);
1704 * Write data to the block device. Only intended for the block device itself
1705 * and the raw driver which basically is a fake block device.
1707 * Does not take i_mutex for the write and thus is not for general purpose
1710 ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
1712 struct file *file = iocb->ki_filp;
1713 struct inode *bd_inode = bdev_file_inode(file);
1714 loff_t size = i_size_read(bd_inode);
1715 struct blk_plug plug;
1718 if (bdev_read_only(I_BDEV(bd_inode)))
1721 if (!iov_iter_count(from))
1724 if (iocb->ki_pos >= size)
1727 iov_iter_truncate(from, size - iocb->ki_pos);
1729 blk_start_plug(&plug);
1730 ret = __generic_file_write_iter(iocb, from);
1732 ret = generic_write_sync(iocb, ret);
1733 blk_finish_plug(&plug);
1736 EXPORT_SYMBOL_GPL(blkdev_write_iter);
1738 ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
1740 struct file *file = iocb->ki_filp;
1741 struct inode *bd_inode = bdev_file_inode(file);
1742 loff_t size = i_size_read(bd_inode);
1743 loff_t pos = iocb->ki_pos;
1749 iov_iter_truncate(to, size);
1750 return generic_file_read_iter(iocb, to);
1752 EXPORT_SYMBOL_GPL(blkdev_read_iter);
1755 * Try to release a page associated with block device when the system
1756 * is under memory pressure.
1758 static int blkdev_releasepage(struct page *page, gfp_t wait)
1760 struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;
1762 if (super && super->s_op->bdev_try_to_free_page)
1763 return super->s_op->bdev_try_to_free_page(super, page, wait);
1765 return try_to_free_buffers(page);
1768 static int blkdev_writepages(struct address_space *mapping,
1769 struct writeback_control *wbc)
1771 if (dax_mapping(mapping)) {
1772 struct block_device *bdev = I_BDEV(mapping->host);
1774 return dax_writeback_mapping_range(mapping, bdev, wbc);
1776 return generic_writepages(mapping, wbc);
1779 static const struct address_space_operations def_blk_aops = {
1780 .readpage = blkdev_readpage,
1781 .readpages = blkdev_readpages,
1782 .writepage = blkdev_writepage,
1783 .write_begin = blkdev_write_begin,
1784 .write_end = blkdev_write_end,
1785 .writepages = blkdev_writepages,
1786 .releasepage = blkdev_releasepage,
1787 .direct_IO = blkdev_direct_IO,
1788 .is_dirty_writeback = buffer_check_dirty_writeback,
1791 const struct file_operations def_blk_fops = {
1792 .open = blkdev_open,
1793 .release = blkdev_close,
1794 .llseek = block_llseek,
1795 .read_iter = blkdev_read_iter,
1796 .write_iter = blkdev_write_iter,
1797 .mmap = generic_file_mmap,
1798 .fsync = blkdev_fsync,
1799 .unlocked_ioctl = block_ioctl,
1800 #ifdef CONFIG_COMPAT
1801 .compat_ioctl = compat_blkdev_ioctl,
1803 .splice_read = generic_file_splice_read,
1804 .splice_write = iter_file_splice_write,
1807 int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
1810 mm_segment_t old_fs = get_fs();
1812 res = blkdev_ioctl(bdev, 0, cmd, arg);
1817 EXPORT_SYMBOL(ioctl_by_bdev);
1820 * lookup_bdev - lookup a struct block_device by name
1821 * @pathname: special file representing the block device
1823 * Get a reference to the blockdevice at @pathname in the current
1824 * namespace if possible and return it. Return ERR_PTR(error)
1827 struct block_device *lookup_bdev(const char *pathname)
1829 struct block_device *bdev;
1830 struct inode *inode;
1834 if (!pathname || !*pathname)
1835 return ERR_PTR(-EINVAL);
1837 error = kern_path(pathname, LOOKUP_FOLLOW, &path);
1839 return ERR_PTR(error);
1841 inode = d_backing_inode(path.dentry);
1843 if (!S_ISBLK(inode->i_mode))
1846 if (!may_open_dev(&path))
1849 bdev = bd_acquire(inode);
1856 bdev = ERR_PTR(error);
1859 EXPORT_SYMBOL(lookup_bdev);
1861 int __invalidate_device(struct block_device *bdev, bool kill_dirty)
1863 struct super_block *sb = get_super(bdev);
1868 * no need to lock the super, get_super holds the
1869 * read mutex so the filesystem cannot go away
1870 * under us (->put_super runs with the write lock
1873 shrink_dcache_sb(sb);
1874 res = invalidate_inodes(sb, kill_dirty);
1877 invalidate_bdev(bdev);
1880 EXPORT_SYMBOL(__invalidate_device);
1882 void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
1884 struct inode *inode, *old_inode = NULL;
1886 spin_lock(&blockdev_superblock->s_inode_list_lock);
1887 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
1888 struct address_space *mapping = inode->i_mapping;
1890 spin_lock(&inode->i_lock);
1891 if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
1892 mapping->nrpages == 0) {
1893 spin_unlock(&inode->i_lock);
1897 spin_unlock(&inode->i_lock);
1898 spin_unlock(&blockdev_superblock->s_inode_list_lock);
1900 * We hold a reference to 'inode' so it couldn't have been
1901 * removed from s_inodes list while we dropped the
1902 * s_inode_list_lock We cannot iput the inode now as we can
1903 * be holding the last reference and we cannot iput it under
1904 * s_inode_list_lock. So we keep the reference and iput it
1910 func(I_BDEV(inode), arg);
1912 spin_lock(&blockdev_superblock->s_inode_list_lock);
1914 spin_unlock(&blockdev_superblock->s_inode_list_lock);