1 files changed, 23 insertions, 33 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 703b728e05fa..7847fbb949ff 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -3685,46 +3685,36 @@ static ssize_t rbd_snap_show(struct device *dev,
 }
 
 /*
- * For an rbd v2 image, shows the pool id, image id, and snapshot id
- * for the parent image.  If there is no parent, simply shows
- * "(no parent image)".
+ * For a v2 image, shows the chain of parent images, separated by empty
+ * lines.  For v1 images or if there is no parent, shows "(no parent
+ * image)".
  */
 static ssize_t rbd_parent_show(struct device *dev,
-			     struct device_attribute *attr,
-			     char *buf)
+			       struct device_attribute *attr,
+			       char *buf)
 {
 	struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
-	struct rbd_spec *spec = rbd_dev->parent_spec;
-	int count;
-	char *bufp = buf;
+	ssize_t count = 0;
 
-	if (!spec)
+	if (!rbd_dev->parent)
 		return sprintf(buf, "(no parent image)\n");
 
-	count = sprintf(bufp, "pool_id %llu\npool_name %s\n",
-			(unsigned long long) spec->pool_id, spec->pool_name);
-	if (count < 0)
-		return count;
-	bufp += count;
-
-	count = sprintf(bufp, "image_id %s\nimage_name %s\n", spec->image_id,
-			spec->image_name ? spec->image_name : "(unknown)");
-	if (count < 0)
-		return count;
-	bufp += count;
-
-	count = sprintf(bufp, "snap_id %llu\nsnap_name %s\n",
-			(unsigned long long) spec->snap_id, spec->snap_name);
-	if (count < 0)
-		return count;
-	bufp += count;
-
-	count = sprintf(bufp, "overlap %llu\n", rbd_dev->parent_overlap);
-	if (count < 0)
-		return count;
-	bufp += count;
-
-	return (ssize_t) (bufp - buf);
+	for ( ; rbd_dev->parent; rbd_dev = rbd_dev->parent) {
+		struct rbd_spec *spec = rbd_dev->parent_spec;
+
+		count += sprintf(&buf[count], "%s"
+			    "pool_id %llu\npool_name %s\n"
+			    "image_id %s\nimage_name %s\n"
+			    "snap_id %llu\nsnap_name %s\n"
+			    "overlap %llu\n",
+			    !count ? "" : "\n", /* first? */
+			    spec->pool_id, spec->pool_name,
+			    spec->image_id, spec->image_name ?: "(unknown)",
+			    spec->snap_id, spec->snap_name,
+			    rbd_dev->parent_overlap);
+	}
+
+	return count;
 }
 
 static ssize_t rbd_image_refresh(struct device *dev,