tier/ctr: Solving DB Lock issue due to write contention from db connections

Problem: The DB on the brick is been accessed by CTR, for write and
tier migrator, for read and write. The write from tier migrator is reseting
the heat counters after a cycle. Since we are using sqlite, two connections
trying to write would cause a db lock contention. As a result CTR used to fail
to update the db.

Solution: Using the same db connection of CTR for reseting the heat counters.
1) Introducted a new IPC FOP for CTR
2) After the query do a ipc syncop to the underlying client xlator associated
   to the brick.
3) CTR in brick will catch the IPC FOP and cleat the heat counters.

Change-Id: I53306bfc08dcdba479deb4ccc154896521336150
BUG: 1260730
Signed-off-by: Joseph Fernandes <josferna@redhat.com>
Reviewed-on: http://review.gluster.org/12031
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Dan Lambright <dlambrig@redhat.com>
Tested-by: Dan Lambright <dlambrig@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/libglusterfs/src/common-utils.h b/libglusterfs/src/common-utils.h
index 2b1290a4380..77a8cdd51c7 100644
--- a/libglusterfs/src/common-utils.h
+++ b/libglusterfs/src/common-utils.h
@@ -126,6 +126,7 @@ enum _gf_client_pid
 
 enum _gf_xlator_ipc_targets {
         GF_IPC_TARGET_CHANGELOG = 0,
+        GF_IPC_TARGET_CTR = 1
 };
 
 typedef enum _gf_boolean gf_boolean_t;