+
+ snapshot_src = (subvol_inum) { 0 };
+ } else {
+ /*
+ * Creating a snapshot - we're not allocating a new inode, but
+ * we do have to lookup the root inode of the subvolume we're
+ * snapshotting and update it (in the new snapshot):
+ */
+
+ if (!snapshot_src.inum) {
+ /* Inode wasn't specified, just snapshot: */
+ struct bch_subvolume s;
+
+ ret = bch2_subvolume_get(trans, snapshot_src.subvol, true,
+ BTREE_ITER_CACHED, &s);
+ if (ret)
+ goto err;
+
+ snapshot_src.inum = le64_to_cpu(s.inode);
+ }
+
+ ret = bch2_inode_peek(trans, &inode_iter, new_inode, snapshot_src,
+ BTREE_ITER_INTENT);
+ if (ret)
+ goto err;
+
+ if (new_inode->bi_subvol != snapshot_src.subvol) {
+ /* Not a subvolume root: */
+ ret = -EINVAL;
+ goto err;
+ }
+
+ /*
+ * If we're not root, we have to own the subvolume being
+ * snapshotted:
+ */
+ if (uid && new_inode->bi_uid != uid) {
+ ret = -EPERM;
+ goto err;
+ }
+
+ flags |= BCH_CREATE_SUBVOL;