rbd: don't print warning if not mapping a parent

The presence of the LAYERING bit in an rbd image's feature mask does
not guarantee the image actually has a parent image.  Currently that
bit is set only when a clone (i.e., image with a parent) is created,
but it is (currently) not cleared if that clone gets flattened back
into a "normal" image.  A "parent_id" query will leave the
parent_spec for the image being mapped a null pointer, but will not
return an error.

Currently, whenever an image with the LAYERED feature gets mapped, a
warning about the use of layered images gets printed.  But we don't
want to do this for a flattened image, so print the warning only
if we find there is a parent spec after the probe.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 4c9869545073536d81581711e678c7df30f4b415..2d34aea772bed4cc94807de0d4719875af669da5 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -4567,13 +4567,14 @@ static int rbd_dev_v2_probe(struct rbd_device *rbd_dev)
                ret = rbd_dev_v2_parent_info(rbd_dev);
                if (ret)
                        goto out_err;
-
                /*
-                * Don't print a warning for parent images.  We can
-                * tell this point because we won't know its pool
-                * name yet (just its pool id).
+                * Print a warning if this image has a parent.
+                * Don't print it if the image now being probed
+                * is itself a parent.  We can tell at this point
+                * because we won't know its pool name yet (just its
+                * pool id).
                 */
-               if (rbd_dev->spec->pool_name)
+               if (rbd_dev->parent_spec && rbd_dev->spec->pool_name)
                        rbd_warn(rbd_dev, "WARNING: kernel layering "
                                        "is EXPERIMENTAL!");
        }