Btrfs: add snapshot/subvolume destroy ioctl

This patch adds snapshot/subvolume destroy ioctl.  A subvolume that isn't being
used and doesn't contains links to other subvolumes can be destroyed.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 6d6d06cb6dfc..0242c8babae9 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -676,6 +676,7 @@ static int btrfs_unfreeze(struct super_block *sb)
 }
 
 static struct super_operations btrfs_super_ops = {
+        .drop_inode     = btrfs_drop_inode,
         .delete_inode   = btrfs_delete_inode,
         .put_super      = btrfs_put_super,
         .sync_fs        = btrfs_sync_fs,