From b97ea2fa1dbb98b1d0eba17c07e6589e9f88b314 Mon Sep 17 00:00:00 2001
From: Alex Elder <elder@inktank.com>
Date: Tue, 9 Oct 2012 13:50:17 -0700
Subject: [PATCH] --- yaml --- r: 347559 b: refs/heads/master c:
 d889140c4a1c5edb6a7bd90392b9d878bfaccfb6 h: refs/heads/master i:   347557:
 9a7c42702e4c6bc0776f5bef746e09523c25a888   347555:
 ef9e7a50824e932bfc953951d155c41b345661e4   347551:
 c64a76d4271418785768c057b41fa568b3b61759 v: v3

---
 [refs]                    |  2 +-
 trunk/drivers/block/rbd.c | 16 +++++++++++++++-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index 1e7d61edd6a4..65c2a1cd8aa9 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 117973fb4c91f3fd913127577e9f71b3aa6cb556
+refs/heads/master: d889140c4a1c5edb6a7bd90392b9d878bfaccfb6
diff --git a/trunk/drivers/block/rbd.c b/trunk/drivers/block/rbd.c
index f11b839166ef..0f260a6e97c4 100644
--- a/trunk/drivers/block/rbd.c
+++ b/trunk/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 @@ static int _rbd_dev_v2_snap_features(struct rbd_device *rbd_dev, u64 snap_id,
 		__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 @@ static int _rbd_dev_v2_snap_features(struct rbd_device *rbd_dev, u64 snap_id,
 	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 @@ static int rbd_dev_v2_probe(struct rbd_device *rbd_dev)
 	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)