rbd: show the entire chain of parent images
Make /sys/bus/rbd/devices/<id>/parent show the entire chain of parent
images. While at it, kernel sprintf() doesn't return negative values,
casting to unsigned long long is no longer necessary and there is no
good reason to split into multiple sprintf() calls.
Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: Alex Elder <elder@linaro.org>
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 703b728..7847fbb 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -3685,46 +3685,36 @@
}
/*
- * 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;
+ for ( ; rbd_dev->parent; rbd_dev = rbd_dev->parent) {
+ struct rbd_spec *spec = rbd_dev->parent_spec;
- 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(&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);
+ }
- 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);
+ return count;
}
static ssize_t rbd_image_refresh(struct device *dev,