glusterd: Get maximum supported op-version in a cluster

gluster volume get <VOLNAME> cluster.opversion gives us the current
op-version on which the cluster is operating. There is no command
that lets the user know the maximum supported op-version that the
cluster can run on.

This patch adds a new global option cluster.max-op-version, that
can be used to retrieve the maximum supported op-version in a
cluster.

Usage:
	# gluster volume get all cluster.max-op-version

Example output:

Option                                  Value
------                                  -----
cluster.max-op-version                  30900

NOTE: The only way to test this feature for now is to set the
GD_OP_VERSION_MAX macro to different values (30800 for 3.8,30900
for 3.9, and so on) and rebuild glusterd. Since the regression test
framework currently doesn't have support to simulate these tests,
there are no accompanying regression tests for this feature. It
should be possible to add tests once glusto comes in and makes it
easier to run a heterogeneous cluster.

Change-Id: I547480ee5e7912664784643e436feb198b6d16d0
BUG: 1365822
Signed-off-by: Samikshan Bairagya <samikshan@gmail.com>
Reviewed-on: http://review.gluster.org/16283
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Atin Mukherjee <amukherj@redhat.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-op-sm.c b/xlators/mgmt/glusterd/src/glusterd-op-sm.c
index c2b0f53dcc4..ffae6296404 100644
--- a/xlators/mgmt/glusterd/src/glusterd-op-sm.c
+++ b/xlators/mgmt/glusterd/src/glusterd-op-sm.c
@@ -67,6 +67,7 @@ glusterd_all_vol_opts valid_all_vol_opts[] = {
         { GLUSTERD_QUORUM_RATIO_KEY },
         { GLUSTERD_SHARED_STORAGE_KEY },
         { GLUSTERD_GLOBAL_OP_VERSION_KEY },
+        { GLUSTERD_MAX_OP_VERSION_KEY },
         { NULL },
 };
 
@@ -2471,6 +2472,25 @@ out:
         return ret;
 }
 
+int
+glusterd_op_get_max_opversion (char **op_errstr, dict_t *rsp_dict)
+{
+        int                     ret             = -1;
+
+        GF_VALIDATE_OR_GOTO (THIS->name, rsp_dict, out);
+
+        ret = dict_set_int32 (rsp_dict, "max-opversion", GD_OP_VERSION_MAX);
+        if (ret) {
+                gf_msg (THIS->name, GF_LOG_ERROR, 0, GD_MSG_DICT_SET_FAILED,
+                        "Setting value for max-opversion to dict failed");
+                goto out;
+        }
+
+out:
+        gf_msg_debug (THIS->name, 0, "Returning %d", ret);
+        return ret;
+}
+
 static int
 glusterd_set_shared_storage (dict_t *dict, char *key, char *value,
                              char **op_errstr)
@@ -7955,6 +7975,7 @@ glusterd_op_free_ctx (glusterd_op_t op, void *ctx)
                 case GD_OP_STATEDUMP_VOLUME:
                 case GD_OP_CLEARLOCKS_VOLUME:
                 case GD_OP_DEFRAG_BRICK_VOLUME:
+                case GD_OP_MAX_OPVERSION:
                         dict_unref (ctx);
                         break;
                 default: