glusterd: Prevent rebalance starting with old clients

Glusterd will prevent rebalance from starting when clients older than
glusterfs-v3.6.0 are connected to a volume. This is needed as running
rebalance with old clients connected could lead to data loss in some
cases. The DHT xlator on newer clients (>= 3.6.0) has been fixed to
prevent the data loss issues.

Change-Id: If58640236382a2fc13f73f6b43777f01713859f7
BUG: 1136201
Signed-off-by: Kaushal M <kaushal@redhat.com>
Reviewed-on: http://review.gluster.org/8583
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Atin Mukherjee <amukherj@redhat.com>
Reviewed-by: Krishnan Parthasarathi <kparthas@redhat.com>
Tested-by: Krishnan Parthasarathi <kparthas@redhat.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-utils.c b/xlators/mgmt/glusterd/src/glusterd-utils.c
index d8ad209caab..375e58e3e87 100644
--- a/xlators/mgmt/glusterd/src/glusterd-utils.c
+++ b/xlators/mgmt/glusterd/src/glusterd-utils.c
@@ -13905,3 +13905,42 @@ out:
         gf_log ("glusterd", GF_LOG_DEBUG, "Returning %d", ret);
         return ret;
 }
+
+int
+glusterd_check_client_op_version_support (char *volname, uint32_t op_version,
+                                          char **op_errstr)
+{
+        int                     ret = 0;
+        xlator_t                *this = NULL;
+        glusterd_conf_t         *priv = NULL;
+        rpc_transport_t         *xprt = NULL;
+
+        this = THIS;
+        GF_ASSERT(this);
+        priv = this->private;
+        GF_ASSERT(priv);
+
+        pthread_mutex_lock (&priv->xprt_lock);
+        list_for_each_entry (xprt, &priv->xprt_list, list) {
+                if ((!strcmp(volname, xprt->peerinfo.volname)) &&
+                    ((op_version > xprt->peerinfo.max_op_version) ||
+                     (op_version < xprt->peerinfo.min_op_version))) {
+                        ret = -1;
+                        break;
+                }
+        }
+        pthread_mutex_unlock (&priv->xprt_lock);
+
+        if (ret) {
+                gf_log (this->name, GF_LOG_ERROR, "One or more clients "
+                        "don't support the required op-version");
+                if (op_errstr)
+                        ret = gf_asprintf (op_errstr, "One or more connected "
+                                           "clients cannot support the feature "
+                                           "being set. These clients need to be"
+                                           " upgraded or disconnected before "
+                                           "running this command again");
+                return -1;
+        }
+        return 0;
+}