diff options
Diffstat (limited to 'fs/block_dev.c')
| -rw-r--r-- | fs/block_dev.c | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c index b3c1efff5e1..8c3c6899ccf 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -18,6 +18,7 @@ #include <linux/module.h> #include <linux/blkpg.h> #include <linux/buffer_head.h> +#include <linux/pagevec.h> #include <linux/writeback.h> #include <linux/mpage.h> #include <linux/mount.h> @@ -174,6 +175,151 @@ blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, iov, offset, nr_segs, blkdev_get_blocks, NULL); } +/* + * Write out and wait upon all the dirty data associated with a block + * device via its mapping. Does not take the superblock lock. + */ +int sync_blockdev(struct block_device *bdev) +{ + int ret = 0; + + if (bdev) + ret = filemap_write_and_wait(bdev->bd_inode->i_mapping); + return ret; +} +EXPORT_SYMBOL(sync_blockdev); + +/* + * Write out and wait upon all dirty data associated with this + * device. Filesystem data as well as the underlying block + * device. Takes the superblock lock. + */ +int fsync_bdev(struct block_device *bdev) +{ + struct super_block *sb = get_super(bdev); + if (sb) { + int res = fsync_super(sb); + drop_super(sb); + return res; + } + return sync_blockdev(bdev); +} + +/** + * freeze_bdev -- lock a filesystem and force it into a consistent state + * @bdev: blockdevice to lock + * + * This takes the block device bd_mount_sem to make sure no new mounts + * happen on bdev until thaw_bdev() is called. + * If a superblock is found on this device, we take the s_umount semaphore + * on it to make sure nobody unmounts until the snapshot creation is done. + * The reference counter (bd_fsfreeze_count) guarantees that only the last + * unfreeze process can unfreeze the frozen filesystem actually when multiple + * freeze requests arrive simultaneously. It counts up in freeze_bdev() and + * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze + * actually. + */ +struct super_block *freeze_bdev(struct block_device *bdev) +{ + struct super_block *sb; + int error = 0; + + mutex_lock(&bdev->bd_fsfreeze_mutex); + if (bdev->bd_fsfreeze_count > 0) { + bdev->bd_fsfreeze_count++; + sb = get_super(bdev); + mutex_unlock(&bdev->bd_fsfreeze_mutex); + return sb; + } + bdev->bd_fsfreeze_count++; + + down(&bdev->bd_mount_sem); + sb = get_super(bdev); + if (sb && !(sb->s_flags & MS_RDONLY)) { + sb->s_frozen = SB_FREEZE_WRITE; + smp_wmb(); + + __fsync_super(sb); + + sb->s_frozen = SB_FREEZE_TRANS; + smp_wmb(); + + sync_blockdev(sb->s_bdev); + + if (sb->s_op->freeze_fs) { + error = sb->s_op->freeze_fs(sb); + if (error) { + printk(KERN_ERR + "VFS:Filesystem freeze failed\n"); + sb->s_frozen = SB_UNFROZEN; + drop_super(sb); + up(&bdev->bd_mount_sem); + bdev->bd_fsfreeze_count--; + mutex_unlock(&bdev->bd_fsfreeze_mutex); + return ERR_PTR(error); + } + } + } + + sync_blockdev(bdev); + mutex_unlock(&bdev->bd_fsfreeze_mutex); + + return sb; /* thaw_bdev releases s->s_umount and bd_mount_sem */ +} +EXPORT_SYMBOL(freeze_bdev); + +/** + * thaw_bdev -- unlock filesystem + * @bdev: blockdevice to unlock + * @sb: associated superblock + * + * Unlocks the filesystem and marks it writeable again after freeze_bdev(). + */ +int thaw_bdev(struct block_device *bdev, struct super_block *sb) +{ + int error = 0; + + mutex_lock(&bdev->bd_fsfreeze_mutex); + if (!bdev->bd_fsfreeze_count) { + mutex_unlock(&bdev->bd_fsfreeze_mutex); + return -EINVAL; + } + + bdev->bd_fsfreeze_count--; + if (bdev->bd_fsfreeze_count > 0) { + if (sb) + drop_super(sb); + mutex_unlock(&bdev->bd_fsfreeze_mutex); + return 0; + } + + if (sb) { + BUG_ON(sb->s_bdev != bdev); + if (!(sb->s_flags & MS_RDONLY)) { + if (sb->s_op->unfreeze_fs) { + error = sb->s_op->unfreeze_fs(sb); + if (error) { + printk(KERN_ERR + "VFS:Filesystem thaw failed\n"); + sb->s_frozen = SB_FREEZE_TRANS; + bdev->bd_fsfreeze_count++; + mutex_unlock(&bdev->bd_fsfreeze_mutex); + return error; + } + } + sb->s_frozen = SB_UNFROZEN; + smp_wmb(); + wake_up(&sb->s_wait_unfrozen); + } + drop_super(sb); + } + + up(&bdev->bd_mount_sem); + mutex_unlock(&bdev->bd_fsfreeze_mutex); + return 0; +} +EXPORT_SYMBOL(thaw_bdev); + static int blkdev_writepage(struct page *page, struct writeback_control *wbc) { return block_write_full_page(page, blkdev_get_block, wbc); |