btrfs: Move may_destroy_subvol() from ioctl.c to inode.c
This is a preparation work to refactor btrfs_ioctl_snap_destroy()
and to allow rmdir(2) to delete an empty subvolume.
Signed-off-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ minor update of the function comment ]
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index f444798..1e51ca4 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4326,6 +4326,61 @@ int btrfs_unlink_subvol(struct btrfs_trans_handle *trans,
return ret;
}
+/*
+ * Helper to check if the subvolume references other subvolumes or if it's
+ * default.
+ */
+noinline int may_destroy_subvol(struct btrfs_root *root)
+{
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct btrfs_path *path;
+ struct btrfs_dir_item *di;
+ struct btrfs_key key;
+ u64 dir_id;
+ int ret;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ /* Make sure this root isn't set as the default subvol */
+ dir_id = btrfs_super_root_dir(fs_info->super_copy);
+ di = btrfs_lookup_dir_item(NULL, fs_info->tree_root, path,
+ dir_id, "default", 7, 0);
+ if (di && !IS_ERR(di)) {
+ btrfs_dir_item_key_to_cpu(path->nodes[0], di, &key);
+ if (key.objectid == root->root_key.objectid) {
+ ret = -EPERM;
+ btrfs_err(fs_info,
+ "deleting default subvolume %llu is not allowed",
+ key.objectid);
+ goto out;
+ }
+ btrfs_release_path(path);
+ }
+
+ key.objectid = root->root_key.objectid;
+ key.type = BTRFS_ROOT_REF_KEY;
+ key.offset = (u64)-1;
+
+ ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
+ if (ret < 0)
+ goto out;
+ BUG_ON(ret == 0);
+
+ ret = 0;
+ if (path->slots[0] > 0) {
+ path->slots[0]--;
+ btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+ if (key.objectid == root->root_key.objectid &&
+ key.type == BTRFS_ROOT_REF_KEY)
+ ret = -ENOTEMPTY;
+ }
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);