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, 2 insertions, 2 deletions

diff --git a/libglusterfs/src/gfdb/gfdb_sqlite3_helper.c b/libglusterfs/src/gfdb/gfdb_sqlite3_helper.c
index 0e27e00ed05..0cc294a5410 100644
--- a/libglusterfs/src/gfdb/gfdb_sqlite3_helper.c
+++ b/libglusterfs/src/gfdb/gfdb_sqlite3_helper.c
@@ -1195,10 +1195,10 @@ gf_sql_clear_counters (gf_sql_connection_t *sql_conn)
 
         CHECK_SQL_CONN (sql_conn, out);
 
-        query_str = "BEGIN;UPDATE "
+        query_str = "UPDATE "
                     GF_FILE_TABLE
                     " SET " GF_COL_READ_FREQ_CNTR " = 0 , "
-                    GF_COL_WRITE_FREQ_CNTR " = 0 ;COMMIT;";
+                    GF_COL_WRITE_FREQ_CNTR " = 0 ;";
 
         ret = sqlite3_exec (sql_conn->sqlite3_db_conn, query_str, NULL, NULL,
                                 &sql_strerror);