dht: make lookup-unhashed=auto do something actually useful

The key concept here is to determine whether a directory is "clean" by
comparing its last-known-good topology to the current one for the
volume.  These are stored as "commit hashes" on the directory and the
volume root respectively.  The volume's commit hash changes whenever a
brick is added or removed, and a fix-layout is done.  A directory's
commit hash changes only when a full rebalance (not just fix-layout)
is done on it.  If all bricks are present and have a directory
commit hash that matches the volume commit hash, then we can assume
that every file is in its "proper" place. Therefore, if we look for
a file in that proper place and don't find it, we can assume it's not
on any other subvolume and *safely* skip the global (broadcast to all)
lookup.

Change-Id: Id6ce4593ba1f7daffa74cfab591cb45960629ae3
BUG: 1219637
Signed-off-by: Jeff Darcy <jdarcy@redhat.com>
Signed-off-by: Shyam <srangana@redhat.com>
Reviewed-on: http://review.gluster.org/7702
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Tested-by: NetBSD Build System
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-rebalance.c b/xlators/mgmt/glusterd/src/glusterd-rebalance.c
index 1566f54695f..9111c07b8fc 100644
--- a/xlators/mgmt/glusterd/src/glusterd-rebalance.c
+++ b/xlators/mgmt/glusterd/src/glusterd-rebalance.c
@@ -284,6 +284,9 @@ glusterd_handle_defrag_start (glusterd_volinfo_t *volinfo, char *op_errstr,
         runner_argprintf ( &runner, "*dht.rebalance-cmd=%d",cmd);
         runner_add_arg (&runner, "--xlator-option");
         runner_argprintf (&runner, "*dht.node-uuid=%s", uuid_utoa(MY_UUID));
+        runner_add_arg (&runner, "--xlator-option");
+        runner_argprintf (&runner, "*dht.commit-hash=%u",
+                          volinfo->rebal.commit_hash);
         runner_add_arg (&runner, "--socket-file");
         runner_argprintf (&runner, "%s",sockfile);
         runner_add_arg (&runner, "--pid-file");
@@ -725,6 +728,7 @@ glusterd_op_rebalance (dict_t *dict, char **op_errstr, dict_t *rsp_dict)
         char                    *task_id_str = NULL;
         dict_t                  *ctx = NULL;
         xlator_t                *this = NULL;
+        uint32_t                commit_hash;
 
         this = THIS;
         GF_ASSERT (this);
@@ -813,6 +817,9 @@ glusterd_op_rebalance (dict_t *dict, char **op_errstr, dict_t *rsp_dict)
                         glusterd_store_perform_node_state_store (volinfo);
                         break;
                 }
+                if (dict_get_uint32 (dict, "commit-hash", &commit_hash) == 0) {
+                        volinfo->rebal.commit_hash = commit_hash;
+                }
                 ret = glusterd_handle_defrag_start (volinfo, msg, sizeof (msg),
                                                     cmd, NULL, GD_OP_REBALANCE);
                 break;