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 <asm/uaccess.h>
36 struct block_device bdev;
37 struct inode vfs_inode;
40 static const struct address_space_operations def_blk_aops;
42 static inline struct bdev_inode *BDEV_I(struct inode *inode)
44 return container_of(inode, struct bdev_inode, vfs_inode);
47 struct block_device *I_BDEV(struct inode *inode)
49 return &BDEV_I(inode)->bdev;
51 EXPORT_SYMBOL(I_BDEV);
53 static void bdev_write_inode(struct block_device *bdev)
55 struct inode *inode = bdev->bd_inode;
58 spin_lock(&inode->i_lock);
59 while (inode->i_state & I_DIRTY) {
60 spin_unlock(&inode->i_lock);
61 ret = write_inode_now(inode, true);
63 char name[BDEVNAME_SIZE];
64 pr_warn_ratelimited("VFS: Dirty inode writeback failed "
65 "for block device %s (err=%d).\n",
66 bdevname(bdev, name), ret);
68 spin_lock(&inode->i_lock);
70 spin_unlock(&inode->i_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 && mapping->nrshadows == 0)
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)
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))
110 /* Size cannot be smaller than the size supported by the device */
111 if (size < bdev_logical_block_size(bdev))
114 /* Don't change the size if it is same as current */
115 if (bdev->bd_block_size != size) {
117 bdev->bd_block_size = size;
118 bdev->bd_inode->i_blkbits = blksize_bits(size);
124 EXPORT_SYMBOL(set_blocksize);
126 int sb_set_blocksize(struct super_block *sb, int size)
128 if (set_blocksize(sb->s_bdev, size))
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);
144 return sb_set_blocksize(sb, size);
147 EXPORT_SYMBOL(sb_min_blocksize);
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);
160 blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
162 struct file *file = iocb->ki_filp;
163 struct inode *inode = file->f_mapping->host;
166 return dax_do_io(iocb, inode, iter, offset, blkdev_get_block,
167 NULL, DIO_SKIP_DIO_COUNT);
168 return __blockdev_direct_IO(iocb, inode, I_BDEV(inode), iter, offset,
169 blkdev_get_block, NULL, NULL,
173 int __sync_blockdev(struct block_device *bdev, int wait)
178 return filemap_flush(bdev->bd_inode->i_mapping);
179 return filemap_write_and_wait(bdev->bd_inode->i_mapping);
183 * Write out and wait upon all the dirty data associated with a block
184 * device via its mapping. Does not take the superblock lock.
186 int sync_blockdev(struct block_device *bdev)
188 return __sync_blockdev(bdev, 1);
190 EXPORT_SYMBOL(sync_blockdev);
193 * Write out and wait upon all dirty data associated with this
194 * device. Filesystem data as well as the underlying block
195 * device. Takes the superblock lock.
197 int fsync_bdev(struct block_device *bdev)
199 struct super_block *sb = get_super(bdev);
201 int res = sync_filesystem(sb);
205 return sync_blockdev(bdev);
207 EXPORT_SYMBOL(fsync_bdev);
210 * freeze_bdev -- lock a filesystem and force it into a consistent state
211 * @bdev: blockdevice to lock
213 * If a superblock is found on this device, we take the s_umount semaphore
214 * on it to make sure nobody unmounts until the snapshot creation is done.
215 * The reference counter (bd_fsfreeze_count) guarantees that only the last
216 * unfreeze process can unfreeze the frozen filesystem actually when multiple
217 * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
218 * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
221 struct super_block *freeze_bdev(struct block_device *bdev)
223 struct super_block *sb;
226 mutex_lock(&bdev->bd_fsfreeze_mutex);
227 if (++bdev->bd_fsfreeze_count > 1) {
229 * We don't even need to grab a reference - the first call
230 * to freeze_bdev grab an active reference and only the last
231 * thaw_bdev drops it.
233 sb = get_super(bdev);
235 mutex_unlock(&bdev->bd_fsfreeze_mutex);
239 sb = get_active_super(bdev);
242 if (sb->s_op->freeze_super)
243 error = sb->s_op->freeze_super(sb);
245 error = freeze_super(sb);
247 deactivate_super(sb);
248 bdev->bd_fsfreeze_count--;
249 mutex_unlock(&bdev->bd_fsfreeze_mutex);
250 return ERR_PTR(error);
252 deactivate_super(sb);
255 mutex_unlock(&bdev->bd_fsfreeze_mutex);
256 return sb; /* thaw_bdev releases s->s_umount */
258 EXPORT_SYMBOL(freeze_bdev);
261 * thaw_bdev -- unlock filesystem
262 * @bdev: blockdevice to unlock
263 * @sb: associated superblock
265 * Unlocks the filesystem and marks it writeable again after freeze_bdev().
267 int thaw_bdev(struct block_device *bdev, struct super_block *sb)
271 mutex_lock(&bdev->bd_fsfreeze_mutex);
272 if (!bdev->bd_fsfreeze_count)
276 if (--bdev->bd_fsfreeze_count > 0)
282 if (sb->s_op->thaw_super)
283 error = sb->s_op->thaw_super(sb);
285 error = thaw_super(sb);
287 bdev->bd_fsfreeze_count++;
288 mutex_unlock(&bdev->bd_fsfreeze_mutex);
292 mutex_unlock(&bdev->bd_fsfreeze_mutex);
295 EXPORT_SYMBOL(thaw_bdev);
297 static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
299 return block_write_full_page(page, blkdev_get_block, wbc);
302 static int blkdev_readpage(struct file * file, struct page * page)
304 return block_read_full_page(page, blkdev_get_block);
307 static int blkdev_readpages(struct file *file, struct address_space *mapping,
308 struct list_head *pages, unsigned nr_pages)
310 return mpage_readpages(mapping, pages, nr_pages, blkdev_get_block);
313 static int blkdev_write_begin(struct file *file, struct address_space *mapping,
314 loff_t pos, unsigned len, unsigned flags,
315 struct page **pagep, void **fsdata)
317 return block_write_begin(mapping, pos, len, flags, pagep,
321 static int blkdev_write_end(struct file *file, struct address_space *mapping,
322 loff_t pos, unsigned len, unsigned copied,
323 struct page *page, void *fsdata)
326 ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
329 page_cache_release(page);
336 * for a block special file file_inode(file)->i_size is zero
337 * so we compute the size by hand (just as in block_read/write above)
339 static loff_t block_llseek(struct file *file, loff_t offset, int whence)
341 struct inode *bd_inode = file->f_mapping->host;
344 mutex_lock(&bd_inode->i_mutex);
345 retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
346 mutex_unlock(&bd_inode->i_mutex);
350 int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
352 struct inode *bd_inode = filp->f_mapping->host;
353 struct block_device *bdev = I_BDEV(bd_inode);
356 error = filemap_write_and_wait_range(filp->f_mapping, start, end);
361 * There is no need to serialise calls to blkdev_issue_flush with
362 * i_mutex and doing so causes performance issues with concurrent
363 * O_SYNC writers to a block device.
365 error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL);
366 if (error == -EOPNOTSUPP)
371 EXPORT_SYMBOL(blkdev_fsync);
374 * bdev_read_page() - Start reading a page from a block device
375 * @bdev: The device to read the page from
376 * @sector: The offset on the device to read the page to (need not be aligned)
377 * @page: The page to read
379 * On entry, the page should be locked. It will be unlocked when the page
380 * has been read. If the block driver implements rw_page synchronously,
381 * that will be true on exit from this function, but it need not be.
383 * Errors returned by this function are usually "soft", eg out of memory, or
384 * queue full; callers should try a different route to read this page rather
385 * than propagate an error back up the stack.
387 * Return: negative errno if an error occurs, 0 if submission was successful.
389 int bdev_read_page(struct block_device *bdev, sector_t sector,
392 const struct block_device_operations *ops = bdev->bd_disk->fops;
393 if (!ops->rw_page || bdev_get_integrity(bdev))
395 return ops->rw_page(bdev, sector + get_start_sect(bdev), page, READ);
397 EXPORT_SYMBOL_GPL(bdev_read_page);
400 * bdev_write_page() - Start writing a page to a block device
401 * @bdev: The device to write the page to
402 * @sector: The offset on the device to write the page to (need not be aligned)
403 * @page: The page to write
404 * @wbc: The writeback_control for the write
406 * On entry, the page should be locked and not currently under writeback.
407 * On exit, if the write started successfully, the page will be unlocked and
408 * under writeback. If the write failed already (eg the driver failed to
409 * queue the page to the device), the page will still be locked. If the
410 * caller is a ->writepage implementation, it will need to unlock the page.
412 * Errors returned by this function are usually "soft", eg out of memory, or
413 * queue full; callers should try a different route to write this page rather
414 * than propagate an error back up the stack.
416 * Return: negative errno if an error occurs, 0 if submission was successful.
418 int bdev_write_page(struct block_device *bdev, sector_t sector,
419 struct page *page, struct writeback_control *wbc)
422 int rw = (wbc->sync_mode == WB_SYNC_ALL) ? WRITE_SYNC : WRITE;
423 const struct block_device_operations *ops = bdev->bd_disk->fops;
424 if (!ops->rw_page || bdev_get_integrity(bdev))
426 set_page_writeback(page);
427 result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, rw);
429 end_page_writeback(page);
434 EXPORT_SYMBOL_GPL(bdev_write_page);
437 * bdev_direct_access() - Get the address for directly-accessibly memory
438 * @bdev: The device containing the memory
439 * @sector: The offset within the device
440 * @addr: Where to put the address of the memory
441 * @pfn: The Page Frame Number for the memory
442 * @size: The number of bytes requested
444 * If a block device is made up of directly addressable memory, this function
445 * will tell the caller the PFN and the address of the memory. The address
446 * may be directly dereferenced within the kernel without the need to call
447 * ioremap(), kmap() or similar. The PFN is suitable for inserting into
450 * Return: negative errno if an error occurs, otherwise the number of bytes
451 * accessible at this address.
453 long bdev_direct_access(struct block_device *bdev, sector_t sector,
454 void __pmem **addr, unsigned long *pfn, long size)
457 const struct block_device_operations *ops = bdev->bd_disk->fops;
460 * The device driver is allowed to sleep, in order to make the
461 * memory directly accessible.
467 if (!ops->direct_access)
469 if ((sector + DIV_ROUND_UP(size, 512)) >
470 part_nr_sects_read(bdev->bd_part))
472 sector += get_start_sect(bdev);
473 if (sector % (PAGE_SIZE / 512))
475 avail = ops->direct_access(bdev, sector, addr, pfn);
478 return min(avail, size);
480 EXPORT_SYMBOL_GPL(bdev_direct_access);
486 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
487 static struct kmem_cache * bdev_cachep __read_mostly;
489 static struct inode *bdev_alloc_inode(struct super_block *sb)
491 struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
494 return &ei->vfs_inode;
497 static void bdev_i_callback(struct rcu_head *head)
499 struct inode *inode = container_of(head, struct inode, i_rcu);
500 struct bdev_inode *bdi = BDEV_I(inode);
502 kmem_cache_free(bdev_cachep, bdi);
505 static void bdev_destroy_inode(struct inode *inode)
507 call_rcu(&inode->i_rcu, bdev_i_callback);
510 static void init_once(void *foo)
512 struct bdev_inode *ei = (struct bdev_inode *) foo;
513 struct block_device *bdev = &ei->bdev;
515 memset(bdev, 0, sizeof(*bdev));
516 mutex_init(&bdev->bd_mutex);
517 INIT_LIST_HEAD(&bdev->bd_inodes);
518 INIT_LIST_HEAD(&bdev->bd_list);
520 INIT_LIST_HEAD(&bdev->bd_holder_disks);
522 inode_init_once(&ei->vfs_inode);
523 /* Initialize mutex for freeze. */
524 mutex_init(&bdev->bd_fsfreeze_mutex);
527 static inline void __bd_forget(struct inode *inode)
529 list_del_init(&inode->i_devices);
530 inode->i_bdev = NULL;
531 inode->i_mapping = &inode->i_data;
534 static void bdev_evict_inode(struct inode *inode)
536 struct block_device *bdev = &BDEV_I(inode)->bdev;
538 truncate_inode_pages_final(&inode->i_data);
539 invalidate_inode_buffers(inode); /* is it needed here? */
541 spin_lock(&bdev_lock);
542 while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) {
543 __bd_forget(list_entry(p, struct inode, i_devices));
545 list_del_init(&bdev->bd_list);
546 spin_unlock(&bdev_lock);
549 static const struct super_operations bdev_sops = {
550 .statfs = simple_statfs,
551 .alloc_inode = bdev_alloc_inode,
552 .destroy_inode = bdev_destroy_inode,
553 .drop_inode = generic_delete_inode,
554 .evict_inode = bdev_evict_inode,
557 static struct dentry *bd_mount(struct file_system_type *fs_type,
558 int flags, const char *dev_name, void *data)
560 return mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC);
563 static struct file_system_type bd_type = {
566 .kill_sb = kill_anon_super,
569 struct super_block *blockdev_superblock __read_mostly;
570 EXPORT_SYMBOL_GPL(blockdev_superblock);
572 void __init bdev_cache_init(void)
575 static struct vfsmount *bd_mnt;
577 bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
578 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
579 SLAB_MEM_SPREAD|SLAB_PANIC),
581 err = register_filesystem(&bd_type);
583 panic("Cannot register bdev pseudo-fs");
584 bd_mnt = kern_mount(&bd_type);
586 panic("Cannot create bdev pseudo-fs");
587 blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */
591 * Most likely _very_ bad one - but then it's hardly critical for small
592 * /dev and can be fixed when somebody will need really large one.
593 * Keep in mind that it will be fed through icache hash function too.
595 static inline unsigned long hash(dev_t dev)
597 return MAJOR(dev)+MINOR(dev);
600 static int bdev_test(struct inode *inode, void *data)
602 return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
605 static int bdev_set(struct inode *inode, void *data)
607 BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
611 static LIST_HEAD(all_bdevs);
613 struct block_device *bdget(dev_t dev)
615 struct block_device *bdev;
618 inode = iget5_locked(blockdev_superblock, hash(dev),
619 bdev_test, bdev_set, &dev);
624 bdev = &BDEV_I(inode)->bdev;
626 if (inode->i_state & I_NEW) {
627 bdev->bd_contains = NULL;
628 bdev->bd_super = NULL;
629 bdev->bd_inode = inode;
630 bdev->bd_block_size = (1 << inode->i_blkbits);
631 bdev->bd_part_count = 0;
632 bdev->bd_invalidated = 0;
633 inode->i_mode = S_IFBLK;
635 inode->i_bdev = bdev;
636 inode->i_data.a_ops = &def_blk_aops;
637 mapping_set_gfp_mask(&inode->i_data, GFP_USER);
638 spin_lock(&bdev_lock);
639 list_add(&bdev->bd_list, &all_bdevs);
640 spin_unlock(&bdev_lock);
641 unlock_new_inode(inode);
646 EXPORT_SYMBOL(bdget);
649 * bdgrab -- Grab a reference to an already referenced block device
650 * @bdev: Block device to grab a reference to.
652 struct block_device *bdgrab(struct block_device *bdev)
654 ihold(bdev->bd_inode);
657 EXPORT_SYMBOL(bdgrab);
659 long nr_blockdev_pages(void)
661 struct block_device *bdev;
663 spin_lock(&bdev_lock);
664 list_for_each_entry(bdev, &all_bdevs, bd_list) {
665 ret += bdev->bd_inode->i_mapping->nrpages;
667 spin_unlock(&bdev_lock);
671 void bdput(struct block_device *bdev)
673 iput(bdev->bd_inode);
676 EXPORT_SYMBOL(bdput);
678 static struct block_device *bd_acquire(struct inode *inode)
680 struct block_device *bdev;
682 spin_lock(&bdev_lock);
683 bdev = inode->i_bdev;
685 ihold(bdev->bd_inode);
686 spin_unlock(&bdev_lock);
689 spin_unlock(&bdev_lock);
691 bdev = bdget(inode->i_rdev);
693 spin_lock(&bdev_lock);
694 if (!inode->i_bdev) {
696 * We take an additional reference to bd_inode,
697 * and it's released in clear_inode() of inode.
698 * So, we can access it via ->i_mapping always
701 ihold(bdev->bd_inode);
702 inode->i_bdev = bdev;
703 inode->i_mapping = bdev->bd_inode->i_mapping;
704 list_add(&inode->i_devices, &bdev->bd_inodes);
706 spin_unlock(&bdev_lock);
711 /* Call when you free inode */
713 void bd_forget(struct inode *inode)
715 struct block_device *bdev = NULL;
717 spin_lock(&bdev_lock);
718 if (!sb_is_blkdev_sb(inode->i_sb))
719 bdev = inode->i_bdev;
721 spin_unlock(&bdev_lock);
724 iput(bdev->bd_inode);
728 * bd_may_claim - test whether a block device can be claimed
729 * @bdev: block device of interest
730 * @whole: whole block device containing @bdev, may equal @bdev
731 * @holder: holder trying to claim @bdev
733 * Test whether @bdev can be claimed by @holder.
736 * spin_lock(&bdev_lock).
739 * %true if @bdev can be claimed, %false otherwise.
741 static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
744 if (bdev->bd_holder == holder)
745 return true; /* already a holder */
746 else if (bdev->bd_holder != NULL)
747 return false; /* held by someone else */
748 else if (bdev->bd_contains == bdev)
749 return true; /* is a whole device which isn't held */
751 else if (whole->bd_holder == bd_may_claim)
752 return true; /* is a partition of a device that is being partitioned */
753 else if (whole->bd_holder != NULL)
754 return false; /* is a partition of a held device */
756 return true; /* is a partition of an un-held device */
760 * bd_prepare_to_claim - prepare to claim a block device
761 * @bdev: block device of interest
762 * @whole: the whole device containing @bdev, may equal @bdev
763 * @holder: holder trying to claim @bdev
765 * Prepare to claim @bdev. This function fails if @bdev is already
766 * claimed by another holder and waits if another claiming is in
767 * progress. This function doesn't actually claim. On successful
768 * return, the caller has ownership of bd_claiming and bd_holder[s].
771 * spin_lock(&bdev_lock). Might release bdev_lock, sleep and regrab
775 * 0 if @bdev can be claimed, -EBUSY otherwise.
777 static int bd_prepare_to_claim(struct block_device *bdev,
778 struct block_device *whole, void *holder)
781 /* if someone else claimed, fail */
782 if (!bd_may_claim(bdev, whole, holder))
785 /* if claiming is already in progress, wait for it to finish */
786 if (whole->bd_claiming) {
787 wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
790 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
791 spin_unlock(&bdev_lock);
793 finish_wait(wq, &wait);
794 spin_lock(&bdev_lock);
803 * bd_start_claiming - start claiming a block device
804 * @bdev: block device of interest
805 * @holder: holder trying to claim @bdev
807 * @bdev is about to be opened exclusively. Check @bdev can be opened
808 * exclusively and mark that an exclusive open is in progress. Each
809 * successful call to this function must be matched with a call to
810 * either bd_finish_claiming() or bd_abort_claiming() (which do not
813 * This function is used to gain exclusive access to the block device
814 * without actually causing other exclusive open attempts to fail. It
815 * should be used when the open sequence itself requires exclusive
816 * access but may subsequently fail.
822 * Pointer to the block device containing @bdev on success, ERR_PTR()
825 static struct block_device *bd_start_claiming(struct block_device *bdev,
828 struct gendisk *disk;
829 struct block_device *whole;
835 * @bdev might not have been initialized properly yet, look up
836 * and grab the outer block device the hard way.
838 disk = get_gendisk(bdev->bd_dev, &partno);
840 return ERR_PTR(-ENXIO);
843 * Normally, @bdev should equal what's returned from bdget_disk()
844 * if partno is 0; however, some drivers (floppy) use multiple
845 * bdev's for the same physical device and @bdev may be one of the
846 * aliases. Keep @bdev if partno is 0. This means claimer
847 * tracking is broken for those devices but it has always been that
851 whole = bdget_disk(disk, 0);
853 whole = bdgrab(bdev);
855 module_put(disk->fops->owner);
858 return ERR_PTR(-ENOMEM);
860 /* prepare to claim, if successful, mark claiming in progress */
861 spin_lock(&bdev_lock);
863 err = bd_prepare_to_claim(bdev, whole, holder);
865 whole->bd_claiming = holder;
866 spin_unlock(&bdev_lock);
869 spin_unlock(&bdev_lock);
876 struct bd_holder_disk {
877 struct list_head list;
878 struct gendisk *disk;
882 static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
883 struct gendisk *disk)
885 struct bd_holder_disk *holder;
887 list_for_each_entry(holder, &bdev->bd_holder_disks, list)
888 if (holder->disk == disk)
893 static int add_symlink(struct kobject *from, struct kobject *to)
895 return sysfs_create_link(from, to, kobject_name(to));
898 static void del_symlink(struct kobject *from, struct kobject *to)
900 sysfs_remove_link(from, kobject_name(to));
904 * bd_link_disk_holder - create symlinks between holding disk and slave bdev
905 * @bdev: the claimed slave bdev
906 * @disk: the holding disk
908 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
910 * This functions creates the following sysfs symlinks.
912 * - from "slaves" directory of the holder @disk to the claimed @bdev
913 * - from "holders" directory of the @bdev to the holder @disk
915 * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
916 * passed to bd_link_disk_holder(), then:
918 * /sys/block/dm-0/slaves/sda --> /sys/block/sda
919 * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
921 * The caller must have claimed @bdev before calling this function and
922 * ensure that both @bdev and @disk are valid during the creation and
923 * lifetime of these symlinks.
929 * 0 on success, -errno on failure.
931 int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
933 struct bd_holder_disk *holder;
936 mutex_lock(&bdev->bd_mutex);
938 WARN_ON_ONCE(!bdev->bd_holder);
940 /* FIXME: remove the following once add_disk() handles errors */
941 if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
944 holder = bd_find_holder_disk(bdev, disk);
950 holder = kzalloc(sizeof(*holder), GFP_KERNEL);
956 INIT_LIST_HEAD(&holder->list);
960 ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
964 ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
968 * bdev could be deleted beneath us which would implicitly destroy
969 * the holder directory. Hold on to it.
971 kobject_get(bdev->bd_part->holder_dir);
973 list_add(&holder->list, &bdev->bd_holder_disks);
977 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
981 mutex_unlock(&bdev->bd_mutex);
984 EXPORT_SYMBOL_GPL(bd_link_disk_holder);
987 * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
988 * @bdev: the calimed slave bdev
989 * @disk: the holding disk
991 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
996 void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
998 struct bd_holder_disk *holder;
1000 mutex_lock(&bdev->bd_mutex);
1002 holder = bd_find_holder_disk(bdev, disk);
1004 if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
1005 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
1006 del_symlink(bdev->bd_part->holder_dir,
1007 &disk_to_dev(disk)->kobj);
1008 kobject_put(bdev->bd_part->holder_dir);
1009 list_del_init(&holder->list);
1013 mutex_unlock(&bdev->bd_mutex);
1015 EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
1019 * flush_disk - invalidates all buffer-cache entries on a disk
1021 * @bdev: struct block device to be flushed
1022 * @kill_dirty: flag to guide handling of dirty inodes
1024 * Invalidates all buffer-cache entries on a disk. It should be called
1025 * when a disk has been changed -- either by a media change or online
1028 static void flush_disk(struct block_device *bdev, bool kill_dirty)
1030 if (__invalidate_device(bdev, kill_dirty)) {
1031 char name[BDEVNAME_SIZE] = "";
1034 disk_name(bdev->bd_disk, 0, name);
1035 printk(KERN_WARNING "VFS: busy inodes on changed media or "
1036 "resized disk %s\n", name);
1041 if (disk_part_scan_enabled(bdev->bd_disk))
1042 bdev->bd_invalidated = 1;
1046 * check_disk_size_change - checks for disk size change and adjusts bdev size.
1047 * @disk: struct gendisk to check
1048 * @bdev: struct bdev to adjust.
1050 * This routine checks to see if the bdev size does not match the disk size
1051 * and adjusts it if it differs.
1053 void check_disk_size_change(struct gendisk *disk, struct block_device *bdev)
1055 loff_t disk_size, bdev_size;
1057 disk_size = (loff_t)get_capacity(disk) << 9;
1058 bdev_size = i_size_read(bdev->bd_inode);
1059 if (disk_size != bdev_size) {
1060 char name[BDEVNAME_SIZE];
1062 disk_name(disk, 0, name);
1064 "%s: detected capacity change from %lld to %lld\n",
1065 name, bdev_size, disk_size);
1066 i_size_write(bdev->bd_inode, disk_size);
1067 flush_disk(bdev, false);
1070 EXPORT_SYMBOL(check_disk_size_change);
1073 * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
1074 * @disk: struct gendisk to be revalidated
1076 * This routine is a wrapper for lower-level driver's revalidate_disk
1077 * call-backs. It is used to do common pre and post operations needed
1078 * for all revalidate_disk operations.
1080 int revalidate_disk(struct gendisk *disk)
1082 struct block_device *bdev;
1085 if (disk->fops->revalidate_disk)
1086 ret = disk->fops->revalidate_disk(disk);
1087 blk_integrity_revalidate(disk);
1088 bdev = bdget_disk(disk, 0);
1092 mutex_lock(&bdev->bd_mutex);
1093 check_disk_size_change(disk, bdev);
1094 bdev->bd_invalidated = 0;
1095 mutex_unlock(&bdev->bd_mutex);
1099 EXPORT_SYMBOL(revalidate_disk);
1102 * This routine checks whether a removable media has been changed,
1103 * and invalidates all buffer-cache-entries in that case. This
1104 * is a relatively slow routine, so we have to try to minimize using
1105 * it. Thus it is called only upon a 'mount' or 'open'. This
1106 * is the best way of combining speed and utility, I think.
1107 * People changing diskettes in the middle of an operation deserve
1110 int check_disk_change(struct block_device *bdev)
1112 struct gendisk *disk = bdev->bd_disk;
1113 const struct block_device_operations *bdops = disk->fops;
1114 unsigned int events;
1116 events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
1117 DISK_EVENT_EJECT_REQUEST);
1118 if (!(events & DISK_EVENT_MEDIA_CHANGE))
1121 flush_disk(bdev, true);
1122 if (bdops->revalidate_disk)
1123 bdops->revalidate_disk(bdev->bd_disk);
1127 EXPORT_SYMBOL(check_disk_change);
1129 void bd_set_size(struct block_device *bdev, loff_t size)
1131 unsigned bsize = bdev_logical_block_size(bdev);
1133 mutex_lock(&bdev->bd_inode->i_mutex);
1134 i_size_write(bdev->bd_inode, size);
1135 mutex_unlock(&bdev->bd_inode->i_mutex);
1136 while (bsize < PAGE_CACHE_SIZE) {
1141 bdev->bd_block_size = bsize;
1142 bdev->bd_inode->i_blkbits = blksize_bits(bsize);
1144 EXPORT_SYMBOL(bd_set_size);
1146 static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
1151 * mutex_lock(part->bd_mutex)
1152 * mutex_lock_nested(whole->bd_mutex, 1)
1155 static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
1157 struct gendisk *disk;
1158 struct module *owner;
1163 if (mode & FMODE_READ)
1165 if (mode & FMODE_WRITE)
1168 * hooks: /n/, see "layering violations".
1171 ret = devcgroup_inode_permission(bdev->bd_inode, perm);
1181 disk = get_gendisk(bdev->bd_dev, &partno);
1184 owner = disk->fops->owner;
1186 disk_block_events(disk);
1187 mutex_lock_nested(&bdev->bd_mutex, for_part);
1188 if (!bdev->bd_openers) {
1189 bdev->bd_disk = disk;
1190 bdev->bd_queue = disk->queue;
1191 bdev->bd_contains = bdev;
1192 bdev->bd_inode->i_flags = disk->fops->direct_access ? S_DAX : 0;
1195 bdev->bd_part = disk_get_part(disk, partno);
1200 if (disk->fops->open) {
1201 ret = disk->fops->open(bdev, mode);
1202 if (ret == -ERESTARTSYS) {
1203 /* Lost a race with 'disk' being
1204 * deleted, try again.
1207 disk_put_part(bdev->bd_part);
1208 bdev->bd_part = NULL;
1209 bdev->bd_disk = NULL;
1210 bdev->bd_queue = NULL;
1211 mutex_unlock(&bdev->bd_mutex);
1212 disk_unblock_events(disk);
1220 bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
1223 * If the device is invalidated, rescan partition
1224 * if open succeeded or failed with -ENOMEDIUM.
1225 * The latter is necessary to prevent ghost
1226 * partitions on a removed medium.
1228 if (bdev->bd_invalidated) {
1230 rescan_partitions(disk, bdev);
1231 else if (ret == -ENOMEDIUM)
1232 invalidate_partitions(disk, bdev);
1237 struct block_device *whole;
1238 whole = bdget_disk(disk, 0);
1243 ret = __blkdev_get(whole, mode, 1);
1246 bdev->bd_contains = whole;
1247 bdev->bd_part = disk_get_part(disk, partno);
1248 if (!(disk->flags & GENHD_FL_UP) ||
1249 !bdev->bd_part || !bdev->bd_part->nr_sects) {
1253 bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
1255 * If the partition is not aligned on a page
1256 * boundary, we can't do dax I/O to it.
1258 if ((bdev->bd_part->start_sect % (PAGE_SIZE / 512)) ||
1259 (bdev->bd_part->nr_sects % (PAGE_SIZE / 512)))
1260 bdev->bd_inode->i_flags &= ~S_DAX;
1263 if (bdev->bd_contains == bdev) {
1265 if (bdev->bd_disk->fops->open)
1266 ret = bdev->bd_disk->fops->open(bdev, mode);
1267 /* the same as first opener case, read comment there */
1268 if (bdev->bd_invalidated) {
1270 rescan_partitions(bdev->bd_disk, bdev);
1271 else if (ret == -ENOMEDIUM)
1272 invalidate_partitions(bdev->bd_disk, bdev);
1275 goto out_unlock_bdev;
1277 /* only one opener holds refs to the module and disk */
1283 bdev->bd_part_count++;
1284 mutex_unlock(&bdev->bd_mutex);
1285 disk_unblock_events(disk);
1289 disk_put_part(bdev->bd_part);
1290 bdev->bd_disk = NULL;
1291 bdev->bd_part = NULL;
1292 bdev->bd_queue = NULL;
1293 if (bdev != bdev->bd_contains)
1294 __blkdev_put(bdev->bd_contains, mode, 1);
1295 bdev->bd_contains = NULL;
1297 mutex_unlock(&bdev->bd_mutex);
1298 disk_unblock_events(disk);
1308 * blkdev_get - open a block device
1309 * @bdev: block_device to open
1310 * @mode: FMODE_* mask
1311 * @holder: exclusive holder identifier
1313 * Open @bdev with @mode. If @mode includes %FMODE_EXCL, @bdev is
1314 * open with exclusive access. Specifying %FMODE_EXCL with %NULL
1315 * @holder is invalid. Exclusive opens may nest for the same @holder.
1317 * On success, the reference count of @bdev is unchanged. On failure,
1324 * 0 on success, -errno on failure.
1326 int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
1328 struct block_device *whole = NULL;
1331 WARN_ON_ONCE((mode & FMODE_EXCL) && !holder);
1333 if ((mode & FMODE_EXCL) && holder) {
1334 whole = bd_start_claiming(bdev, holder);
1335 if (IS_ERR(whole)) {
1337 return PTR_ERR(whole);
1341 res = __blkdev_get(bdev, mode, 0);
1344 struct gendisk *disk = whole->bd_disk;
1346 /* finish claiming */
1347 mutex_lock(&bdev->bd_mutex);
1348 spin_lock(&bdev_lock);
1351 BUG_ON(!bd_may_claim(bdev, whole, holder));
1353 * Note that for a whole device bd_holders
1354 * will be incremented twice, and bd_holder
1355 * will be set to bd_may_claim before being
1358 whole->bd_holders++;
1359 whole->bd_holder = bd_may_claim;
1361 bdev->bd_holder = holder;
1364 /* tell others that we're done */
1365 BUG_ON(whole->bd_claiming != holder);
1366 whole->bd_claiming = NULL;
1367 wake_up_bit(&whole->bd_claiming, 0);
1369 spin_unlock(&bdev_lock);
1372 * Block event polling for write claims if requested. Any
1373 * write holder makes the write_holder state stick until
1374 * all are released. This is good enough and tracking
1375 * individual writeable reference is too fragile given the
1376 * way @mode is used in blkdev_get/put().
1378 if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder &&
1379 (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
1380 bdev->bd_write_holder = true;
1381 disk_block_events(disk);
1384 mutex_unlock(&bdev->bd_mutex);
1390 EXPORT_SYMBOL(blkdev_get);
1393 * blkdev_get_by_path - open a block device by name
1394 * @path: path to the block device to open
1395 * @mode: FMODE_* mask
1396 * @holder: exclusive holder identifier
1398 * Open the blockdevice described by the device file at @path. @mode
1399 * and @holder are identical to blkdev_get().
1401 * On success, the returned block_device has reference count of one.
1407 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1409 struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
1412 struct block_device *bdev;
1415 bdev = lookup_bdev(path);
1419 err = blkdev_get(bdev, mode, holder);
1421 return ERR_PTR(err);
1423 if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) {
1424 blkdev_put(bdev, mode);
1425 return ERR_PTR(-EACCES);
1430 EXPORT_SYMBOL(blkdev_get_by_path);
1433 * blkdev_get_by_dev - open a block device by device number
1434 * @dev: device number of block device to open
1435 * @mode: FMODE_* mask
1436 * @holder: exclusive holder identifier
1438 * Open the blockdevice described by device number @dev. @mode and
1439 * @holder are identical to blkdev_get().
1441 * Use it ONLY if you really do not have anything better - i.e. when
1442 * you are behind a truly sucky interface and all you are given is a
1443 * device number. _Never_ to be used for internal purposes. If you
1444 * ever need it - reconsider your API.
1446 * On success, the returned block_device has reference count of one.
1452 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1454 struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
1456 struct block_device *bdev;
1461 return ERR_PTR(-ENOMEM);
1463 err = blkdev_get(bdev, mode, holder);
1465 return ERR_PTR(err);
1469 EXPORT_SYMBOL(blkdev_get_by_dev);
1471 static int blkdev_open(struct inode * inode, struct file * filp)
1473 struct block_device *bdev;
1476 * Preserve backwards compatibility and allow large file access
1477 * even if userspace doesn't ask for it explicitly. Some mkfs
1478 * binary needs it. We might want to drop this workaround
1479 * during an unstable branch.
1481 filp->f_flags |= O_LARGEFILE;
1483 if (filp->f_flags & O_NDELAY)
1484 filp->f_mode |= FMODE_NDELAY;
1485 if (filp->f_flags & O_EXCL)
1486 filp->f_mode |= FMODE_EXCL;
1487 if ((filp->f_flags & O_ACCMODE) == 3)
1488 filp->f_mode |= FMODE_WRITE_IOCTL;
1490 bdev = bd_acquire(inode);
1494 filp->f_mapping = bdev->bd_inode->i_mapping;
1496 return blkdev_get(bdev, filp->f_mode, filp);
1499 static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
1501 struct gendisk *disk = bdev->bd_disk;
1502 struct block_device *victim = NULL;
1504 mutex_lock_nested(&bdev->bd_mutex, for_part);
1506 bdev->bd_part_count--;
1508 if (!--bdev->bd_openers) {
1509 WARN_ON_ONCE(bdev->bd_holders);
1510 sync_blockdev(bdev);
1513 * ->release can cause the queue to disappear, so flush all
1514 * dirty data before.
1516 bdev_write_inode(bdev);
1518 if (bdev->bd_contains == bdev) {
1519 if (disk->fops->release)
1520 disk->fops->release(disk, mode);
1522 if (!bdev->bd_openers) {
1523 struct module *owner = disk->fops->owner;
1525 disk_put_part(bdev->bd_part);
1526 bdev->bd_part = NULL;
1527 bdev->bd_disk = NULL;
1528 if (bdev != bdev->bd_contains)
1529 victim = bdev->bd_contains;
1530 bdev->bd_contains = NULL;
1535 mutex_unlock(&bdev->bd_mutex);
1538 __blkdev_put(victim, mode, 1);
1541 void blkdev_put(struct block_device *bdev, fmode_t mode)
1543 mutex_lock(&bdev->bd_mutex);
1545 if (mode & FMODE_EXCL) {
1549 * Release a claim on the device. The holder fields
1550 * are protected with bdev_lock. bd_mutex is to
1551 * synchronize disk_holder unlinking.
1553 spin_lock(&bdev_lock);
1555 WARN_ON_ONCE(--bdev->bd_holders < 0);
1556 WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0);
1558 /* bd_contains might point to self, check in a separate step */
1559 if ((bdev_free = !bdev->bd_holders))
1560 bdev->bd_holder = NULL;
1561 if (!bdev->bd_contains->bd_holders)
1562 bdev->bd_contains->bd_holder = NULL;
1564 spin_unlock(&bdev_lock);
1567 * If this was the last claim, remove holder link and
1568 * unblock evpoll if it was a write holder.
1570 if (bdev_free && bdev->bd_write_holder) {
1571 disk_unblock_events(bdev->bd_disk);
1572 bdev->bd_write_holder = false;
1577 * Trigger event checking and tell drivers to flush MEDIA_CHANGE
1578 * event. This is to ensure detection of media removal commanded
1579 * from userland - e.g. eject(1).
1581 disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE);
1583 mutex_unlock(&bdev->bd_mutex);
1585 __blkdev_put(bdev, mode, 0);
1587 EXPORT_SYMBOL(blkdev_put);
1589 static int blkdev_close(struct inode * inode, struct file * filp)
1591 struct block_device *bdev = I_BDEV(filp->f_mapping->host);
1592 blkdev_put(bdev, filp->f_mode);
1596 static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
1598 struct block_device *bdev = I_BDEV(file->f_mapping->host);
1599 fmode_t mode = file->f_mode;
1602 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
1603 * to updated it before every ioctl.
1605 if (file->f_flags & O_NDELAY)
1606 mode |= FMODE_NDELAY;
1608 mode &= ~FMODE_NDELAY;
1610 return blkdev_ioctl(bdev, mode, cmd, arg);
1614 * Write data to the block device. Only intended for the block device itself
1615 * and the raw driver which basically is a fake block device.
1617 * Does not take i_mutex for the write and thus is not for general purpose
1620 ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
1622 struct file *file = iocb->ki_filp;
1623 struct inode *bd_inode = file->f_mapping->host;
1624 loff_t size = i_size_read(bd_inode);
1625 struct blk_plug plug;
1628 if (bdev_read_only(I_BDEV(bd_inode)))
1631 if (!iov_iter_count(from))
1634 if (iocb->ki_pos >= size)
1637 iov_iter_truncate(from, size - iocb->ki_pos);
1639 blk_start_plug(&plug);
1640 ret = __generic_file_write_iter(iocb, from);
1643 err = generic_write_sync(file, iocb->ki_pos - ret, ret);
1647 blk_finish_plug(&plug);
1650 EXPORT_SYMBOL_GPL(blkdev_write_iter);
1652 ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
1654 struct file *file = iocb->ki_filp;
1655 struct inode *bd_inode = file->f_mapping->host;
1656 loff_t size = i_size_read(bd_inode);
1657 loff_t pos = iocb->ki_pos;
1663 iov_iter_truncate(to, size);
1664 return generic_file_read_iter(iocb, to);
1666 EXPORT_SYMBOL_GPL(blkdev_read_iter);
1669 * Try to release a page associated with block device when the system
1670 * is under memory pressure.
1672 static int blkdev_releasepage(struct page *page, gfp_t wait)
1674 struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;
1676 if (super && super->s_op->bdev_try_to_free_page)
1677 return super->s_op->bdev_try_to_free_page(super, page, wait);
1679 return try_to_free_buffers(page);
1682 static const struct address_space_operations def_blk_aops = {
1683 .readpage = blkdev_readpage,
1684 .readpages = blkdev_readpages,
1685 .writepage = blkdev_writepage,
1686 .write_begin = blkdev_write_begin,
1687 .write_end = blkdev_write_end,
1688 .writepages = generic_writepages,
1689 .releasepage = blkdev_releasepage,
1690 .direct_IO = blkdev_direct_IO,
1691 .is_dirty_writeback = buffer_check_dirty_writeback,
1694 const struct file_operations def_blk_fops = {
1695 .open = blkdev_open,
1696 .release = blkdev_close,
1697 .llseek = block_llseek,
1698 .read_iter = blkdev_read_iter,
1699 .write_iter = blkdev_write_iter,
1700 .mmap = generic_file_mmap,
1701 .fsync = blkdev_fsync,
1702 .unlocked_ioctl = block_ioctl,
1703 #ifdef CONFIG_COMPAT
1704 .compat_ioctl = compat_blkdev_ioctl,
1706 .splice_read = generic_file_splice_read,
1707 .splice_write = iter_file_splice_write,
1710 int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
1713 mm_segment_t old_fs = get_fs();
1715 res = blkdev_ioctl(bdev, 0, cmd, arg);
1720 EXPORT_SYMBOL(ioctl_by_bdev);
1723 * lookup_bdev - lookup a struct block_device by name
1724 * @pathname: special file representing the block device
1726 * Get a reference to the blockdevice at @pathname in the current
1727 * namespace if possible and return it. Return ERR_PTR(error)
1730 struct block_device *lookup_bdev(const char *pathname)
1732 struct block_device *bdev;
1733 struct inode *inode;
1737 if (!pathname || !*pathname)
1738 return ERR_PTR(-EINVAL);
1740 error = kern_path(pathname, LOOKUP_FOLLOW, &path);
1742 return ERR_PTR(error);
1744 inode = d_backing_inode(path.dentry);
1746 if (!S_ISBLK(inode->i_mode))
1749 if (path.mnt->mnt_flags & MNT_NODEV)
1752 bdev = bd_acquire(inode);
1759 bdev = ERR_PTR(error);
1762 EXPORT_SYMBOL(lookup_bdev);
1764 int __invalidate_device(struct block_device *bdev, bool kill_dirty)
1766 struct super_block *sb = get_super(bdev);
1771 * no need to lock the super, get_super holds the
1772 * read mutex so the filesystem cannot go away
1773 * under us (->put_super runs with the write lock
1776 shrink_dcache_sb(sb);
1777 res = invalidate_inodes(sb, kill_dirty);
1780 invalidate_bdev(bdev);
1783 EXPORT_SYMBOL(__invalidate_device);
1785 void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
1787 struct inode *inode, *old_inode = NULL;
1789 spin_lock(&blockdev_superblock->s_inode_list_lock);
1790 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
1791 struct address_space *mapping = inode->i_mapping;
1793 spin_lock(&inode->i_lock);
1794 if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
1795 mapping->nrpages == 0) {
1796 spin_unlock(&inode->i_lock);
1800 spin_unlock(&inode->i_lock);
1801 spin_unlock(&blockdev_superblock->s_inode_list_lock);
1803 * We hold a reference to 'inode' so it couldn't have been
1804 * removed from s_inodes list while we dropped the
1805 * s_inode_list_lock We cannot iput the inode now as we can
1806 * be holding the last reference and we cannot iput it under
1807 * s_inode_list_lock. So we keep the reference and iput it
1813 func(I_BDEV(inode), arg);
1815 spin_lock(&blockdev_superblock->s_inode_list_lock);
1817 spin_unlock(&blockdev_superblock->s_inode_list_lock);