Btrfs: cleanup: don't check the same thing twice

btrfs_read_fs_root_no_name() already checks if btrfs_root_refs()
is zero and returns ENOENT in this case. There is no need to do
it again in six places.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

fs/btrfs/export.c

@@ -82,11 +82,6 @@ static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
 		goto fail;
 	}
 
-	if (btrfs_root_refs(&root->root_item) == 0) {
-		err = -ENOENT;
-		goto fail;
-	}
-
 	key.objectid = objectid;
 	btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
 	key.offset = 0;

fs/btrfs/file.c

@@ -308,10 +308,6 @@ static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info,
 		ret = PTR_ERR(inode_root);
 		goto cleanup;
 	}
-	if (btrfs_root_refs(&inode_root->root_item) == 0) {
-		ret = -ENOENT;
-		goto cleanup;
-	}
 
 	key.objectid = defrag->ino;
 	btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);

fs/btrfs/inode.c

@@ -2262,11 +2262,6 @@ static noinline int relink_extent_backref(struct btrfs_path *path,
 			return 0;
 		return PTR_ERR(root);
 	}
-	if (btrfs_root_refs(&root->root_item) == 0) {
-		srcu_read_unlock(&fs_info->subvol_srcu, index);
-		/* parse ENOENT to 0 */
-		return 0;
-	}
 
 	/* step 2: get inode */
 	key.objectid = backref->inum;
@@ -4821,11 +4816,6 @@ static int fixup_tree_root_location(struct btrfs_root *root,
 		goto out;
 	}
 
-	if (btrfs_root_refs(&new_root->root_item) == 0) {
-		err = -ENOENT;
-		goto out;
-	}
-
 	*sub_root = new_root;
 	location->objectid = btrfs_root_dirid(&new_root->root_item);
 	location->type = BTRFS_INODE_ITEM_KEY;

fs/btrfs/ioctl.c

@@ -2951,11 +2951,6 @@ static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp)
 		goto out;
 	}
 
-	if (btrfs_root_refs(&new_root->root_item) == 0) {
-		ret = -ENOENT;
-		goto out;
-	}
-
 	path = btrfs_alloc_path();
 	if (!path) {
 		ret = -ENOMEM;

fs/btrfs/super.c

@@ -775,9 +775,6 @@ static struct dentry *get_default_root(struct super_block *sb,
 	if (IS_ERR(new_root))
 		return ERR_CAST(new_root);
 
-	if (btrfs_root_refs(&new_root->root_item) == 0)
-		return ERR_PTR(-ENOENT);
-
 	dir_id = btrfs_root_dirid(&new_root->root_item);
 setup_root:
 	location.objectid = dir_id;