rbd: implement feature checks
Version 2 images have two sets of feature bit fields. The first
indicates features possibly used by the image. The second indicates
features that the client *must* support in order to use the image.
When an image (or snapshot) is first examined, we need to make sure
that the local implementation supports the image's required
features. If not, fail the probe for the image.
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 f11b839..0f260a6 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -70,6 +70,14 @@
#define RBD_IMAGE_ID_LEN_MAX 64
#define RBD_OBJ_PREFIX_LEN_MAX 64
+/* Feature bits */
+
+#define RBD_FEATURE_LAYERING 1
+
+/* Features supported by this (client software) implementation. */
+
+#define RBD_FEATURES_ALL (0)
+
/*
* An RBD device name will be "rbd#", where the "rbd" comes from
* RBD_DRV_NAME above, and # is a unique integer identifier.
@@ -2226,6 +2234,7 @@
__le64 features;
__le64 incompat;
} features_buf = { 0 };
+ u64 incompat;
int ret;
ret = rbd_req_sync_exec(rbd_dev, rbd_dev->header_name,
@@ -2236,6 +2245,11 @@
dout("%s: rbd_req_sync_exec returned %d\n", __func__, ret);
if (ret < 0)
return ret;
+
+ incompat = le64_to_cpu(features_buf.incompat);
+ if (incompat & ~RBD_FEATURES_ALL)
+ return -ENOTSUPP;
+
*snap_features = le64_to_cpu(features_buf.features);
dout(" snap_id 0x%016llx features = 0x%016llx incompat = 0x%016llx\n",
@@ -2977,7 +2991,7 @@
if (ret < 0)
goto out_err;
- /* Get the features for the image */
+ /* Get the and check features for the image */
ret = rbd_dev_v2_features(rbd_dev);
if (ret < 0)