Btrf: cleanup: don't check for root_refs == 0 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 three more places.

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

fs/btrfs/file.c

@@ -310,11 +310,6 @@ static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info,
 		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);
 	key.offset = 0;

fs/btrfs/relocation.c

@@ -2354,9 +2354,6 @@ again:
 			if (IS_ERR(root))
 				continue;
 
-			if (btrfs_root_refs(&root->root_item) == 0)
-				continue;
-
 			trans = btrfs_join_transaction(root);
 			BUG_ON(IS_ERR(trans));
 

fs/btrfs/scrub.c

@@ -3217,11 +3217,6 @@ static int copy_nocow_pages_for_inode(u64 inum, u64 offset, u64 root, void *ctx)
 		return PTR_ERR(local_root);
 	}
 
-	if (btrfs_root_refs(&local_root->root_item) == 0) {
-		srcu_read_unlock(&fs_info->subvol_srcu, srcu_index);
-		return -ENOENT;
-	}
-
 	key.type = BTRFS_INODE_ITEM_KEY;
 	key.objectid = inum;
 	key.offset = 0;