glusterd, cli: handle uuid conflicts in probe gracefully

A commonly faced problem among glusterfs users is: after a fresh
installation of glusterfs in a virtual machine, the VM image is
cloned to make multiple instances of the server. This breaks
glusterd because right after glusterfs installation on the first
boot glusterd would have created the node UUID and this gets
inherited into the clone. The result is wierd behavior at the time
of peer probe where glusterd does not (yet) deal with UUID
collisions in a user friendly way.

With this patch the peer which got the probe request will compare
the uuid of the machine which send the probe request with its own
uuid and send the proper error to cli if the uuids are same.

Change-Id: I091741ec863431fb6480a09a3f4c68a0906a3339
BUG: 811493
Signed-off-by: Raghavendra Bhat <raghavendra@redhat.com>
Reviewed-on: http://review.gluster.com/3612
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Amar Tumballi <amarts@redhat.com>
Reviewed-by: Anand Avati <avati@redhat.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-handler.c b/xlators/mgmt/glusterd/src/glusterd-handler.c
index 51b859857b2..63d53ef2a1e 100644
--- a/xlators/mgmt/glusterd/src/glusterd-handler.c
+++ b/xlators/mgmt/glusterd/src/glusterd-handler.c
@@ -1753,6 +1753,20 @@ glusterd_handle_probe_query (rpcsvc_request_t *req)
         gf_log ("glusterd", GF_LOG_INFO,
                 "Received probe from uuid: %s", uuid_utoa (probe_req.uuid));
 
+        /* Check for uuid collision and handle it in a user friendly way by
+         * sending the error.
+         */
+        if (!uuid_compare (probe_req.uuid, MY_UUID)) {
+                gf_log (THIS->name, GF_LOG_ERROR, "Peer uuid %s is same as "
+                        "local uuid. Please check the uuid of both the peers "
+                        "from %s/%s", uuid_utoa (probe_req.uuid),
+                        GLUSTERD_DEFAULT_WORKDIR, GLUSTERD_INFO_FILE);
+                rsp.op_ret = -1;
+                rsp.op_errno = GF_PROBE_SAME_UUID;
+                rsp.port = port;
+                goto respond;
+        }
+
         ret = glusterd_remote_hostname_get (req, remote_hostname,
                                             sizeof (remote_hostname));
         if (ret) {
@@ -1777,6 +1791,7 @@ glusterd_handle_probe_query (rpcsvc_request_t *req)
                 }
         }
 
+respond:
         uuid_copy (rsp.uuid, conf->uuid);
 
         rsp.hostname = probe_req.hostname;