glusterd: Start rebalance only where required

Gluster was starting rebalance processes on peers where it wasn't
required in two cases.
- For a normal rebalance command on a volume, rebalance processes were
  started on all peers instead of just the peers which contain bricks of
  the volume
- For rebalance process being restarted by a volume sync, caused by a
  new peer being probed or a peer restarting, rebalance processes were
  started on all peers, for both a normal rebalance and for remove-brick
  needing rebalance.

This patch adds a new check before starting rebalance process in the
above two cases.
- For rebalance process required by a rebalance command, each peer will
  check if it contains atleast one brick of the volume
- For rebalance process required by a remove-brick command, each peer
  will check if it contains atleast one of the bricks being removed

Change-Id: I512da16994f0d5482889c3a009c46dc20a8a15bb
BUG: 1031887
Signed-off-by: Kaushal M <kaushal@redhat.com>
Reviewed-on: http://review.gluster.org/6301
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Krutika Dhananjay <kdhananj@redhat.com>
Reviewed-by: Anand Avati <avati@redhat.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-rebalance.c b/xlators/mgmt/glusterd/src/glusterd-rebalance.c
index 031de2c9b..214f40c66 100644
--- a/xlators/mgmt/glusterd/src/glusterd-rebalance.c
+++ b/xlators/mgmt/glusterd/src/glusterd-rebalance.c
@@ -665,9 +665,11 @@ glusterd_op_rebalance (dict_t *dict, char **op_errstr, dict_t *rsp_dict)
                         uuid_parse (task_id_str, volinfo->rebal.rebalance_id) ;
                         volinfo->rebal.op = GD_OP_REBALANCE;
                 }
+                if (!gd_should_i_start_rebalance (volinfo))
+                        break;
                 ret = glusterd_handle_defrag_start (volinfo, msg, sizeof (msg),
                                                     cmd, NULL, GD_OP_REBALANCE);
-                 break;
+                break;
         case GF_DEFRAG_CMD_STOP:
                 /* Clear task-id only on explicitly stopping rebalance.
                  * Also clear the stored operation, so it doesn't cause trouble