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>

2 files changed, 34 insertions, 1 deletions

diff --git a/xlators/features/changetimerecorder/src/changetimerecorder.c b/xlators/features/changetimerecorder/src/changetimerecorder.c
index 5df9cb9097b..609be07fa7e 100644
--- a/xlators/features/changetimerecorder/src/changetimerecorder.c
+++ b/xlators/features/changetimerecorder/src/changetimerecorder.c
@@ -1379,6 +1379,36 @@ out:
                     fd, size, off, flags, xdata);
         return 0;
 }
+
+/*******************************ctr_ipc****************************************/
+
+/* IPC Call from tier migrator to clear the heat on the DB */
+int32_t
+ctr_ipc (call_frame_t *frame, xlator_t *this, int32_t op, dict_t *xdata)
+{
+        int ret                         = -1;
+        gf_ctr_private_t *_priv         = NULL;
+
+        GF_ASSERT(this);
+        _priv = this->private;
+        GF_ASSERT (_priv);
+        GF_ASSERT(_priv->_db_conn);
+
+        if (op != GF_IPC_TARGET_CTR)
+                goto wind;
+
+        ret = clear_files_heat (_priv->_db_conn);
+
+        STACK_UNWIND_STRICT (ipc, frame, ret, 0, NULL);
+        return 0;
+
+ wind:
+        STACK_WIND (frame, default_ipc_cbk, FIRST_CHILD (this),
+                    FIRST_CHILD (this)->fops->ipc, op, xdata);
+        return 0;
+}
+
+
 /******************************************************************************/
 
 int
@@ -1596,7 +1626,9 @@ struct xlator_fops fops = {
         .writev      = ctr_writev,
         .setattr      = ctr_setattr,
         /*read fops*/
-        .readv       = ctr_readv
+        .readv       = ctr_readv,
+        /* IPC call*/
+        .ipc          = ctr_ipc
 };
 
 struct xlator_cbks cbks = {
diff --git a/xlators/features/changetimerecorder/src/ctr-helper.h b/xlators/features/changetimerecorder/src/ctr-helper.h
index 0c4f3e2cd8c..cff79756603 100644
--- a/xlators/features/changetimerecorder/src/ctr-helper.h
+++ b/xlators/features/changetimerecorder/src/ctr-helper.h
@@ -17,6 +17,7 @@
 #include "iatt.h"
 #include "glusterfs.h"
 #include "xlator.h"
+#include "defaults.h"
 #include "logging.h"
 #include "common-utils.h"
 #include <time.h>