Btrfs: fix wrong reserved space when deleting a snapshot/subvolume

When deleting a snapshot/subvolume, we need remove root ref/backref,
dir entries and update the dir inode, so we must reserve free space
for those operations.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 56d92549389c61af18421aa5470821e55ce7c8c6..b908960c97466612a3ec6e631b6134536c8d86fb 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2064,6 +2064,8 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
        struct btrfs_root *dest = NULL;
        struct btrfs_ioctl_vol_args *vol_args;
        struct btrfs_trans_handle *trans;
+       struct btrfs_block_rsv block_rsv;
+       u64 qgroup_reserved;
        int namelen;
        int ret;
        int err = 0;
@@ -2153,12 +2155,23 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
        if (err)
                goto out_up_write;
 
+       btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
+       /*
+        * One for dir inode, two for dir entries, two for root
+        * ref/backref.
+        */
+       err = btrfs_subvolume_reserve_metadata(root, &block_rsv,
+                                              5, &qgroup_reserved);
+       if (err)
+               goto out_up_write;
+
        trans = btrfs_start_transaction(root, 0);
        if (IS_ERR(trans)) {
                err = PTR_ERR(trans);
-               goto out_up_write;
+               goto out_release;
        }
-       trans->block_rsv = &root->fs_info->global_block_rsv;
+       trans->block_rsv = &block_rsv;
+       trans->bytes_reserved = block_rsv.size;
 
        ret = btrfs_unlink_subvol(trans, root, dir,
                                dest->root_key.objectid,
@@ -2188,10 +2201,14 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
                }
        }
 out_end_trans:
+       trans->block_rsv = NULL;
+       trans->bytes_reserved = 0;
        ret = btrfs_end_transaction(trans, root);
        if (ret && !err)
                err = ret;
        inode->i_flags |= S_DEAD;
+out_release:
+       btrfs_subvolume_release_metadata(root, &block_rsv, qgroup_reserved);
 out_up_write:
        up_write(&root->fs_info->subvol_sem);
 out_unlock: