rbd: mark the original request as done if stat request fails

If stat request fails with something other than -ENOENT (which just
means that we need to copyup), the original object request is never
marked as done and therefore never completed.  Fix this by moving the
mark done + complete snippet from rbd_img_obj_parent_read_full() into
rbd_img_obj_exists_callback().  The former remains covered, as the
latter is its only caller (through rbd_img_obj_request_submit()).
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>
Reviewed-by: NAlex Elder <elder@linaro.org>
Reviewed-by: NDavid Disseldorp <ddiss@suse.de>

drivers/block/rbd.c

@@ -2742,8 +2742,8 @@ rbd_img_obj_parent_read_full_callback(struct rbd_img_request *img_request)
  * When the read completes, this page array will be transferred to
  * the original object request for the copyup operation.
  *
- * If an error occurs, record it as the result of the original
- * object request and mark it done so it gets completed.
+ * If an error occurs, it is recorded as the result of the original
+ * object request in rbd_img_obj_exists_callback().
  */
 static int rbd_img_obj_parent_read_full(struct rbd_obj_request *obj_request)
 {
@@ -2813,10 +2813,6 @@ static int rbd_img_obj_parent_read_full(struct rbd_obj_request *obj_request)
 		ceph_release_page_vector(pages, page_count);
 	if (parent_request)
 		rbd_img_request_put(parent_request);
-	obj_request->result = result;
-	obj_request->xferred = 0;
-	obj_request_done_set(obj_request);
-
 	return result;
 }
 
@@ -2868,19 +2864,25 @@ static void rbd_img_obj_exists_callback(struct rbd_obj_request *obj_request)
 		obj_request_existence_set(orig_request, true);
 	} else if (result == -ENOENT) {
 		obj_request_existence_set(orig_request, false);
-	} else if (result) {
-		orig_request->result = result;
-		goto out;
+	} else {
+		goto fail_orig_request;
 	}
 
 	/*
 	 * Resubmit the original request now that we have recorded
 	 * whether the target object exists.
 	 */
-	orig_request->result = rbd_img_obj_request_submit(orig_request);
-out:
-	if (orig_request->result)
-		rbd_obj_request_complete(orig_request);
+	result = rbd_img_obj_request_submit(orig_request);
+	if (result)
+		goto fail_orig_request;
+
+	return;
+
+fail_orig_request:
+	orig_request->result = result;
+	orig_request->xferred = 0;
+	obj_request_done_set(orig_request);
+	rbd_obj_request_complete(orig_request);
 }
 
 static int rbd_img_obj_exists_submit(struct rbd_obj_request *obj_request)