md-cache: Register the list of xattrs with cache-invalidation

Issue:
md-cache caches a specified list of xattrs, and when cache invalidation
is enabled, it makes sense to recieve invalidation only when those xattrs
are modified by other clients. But the current implementation of upcall
is that, it will send invalidation when any of the on-disk xattrs is modified.

Solution:
md-cache sends a list of xattrs that it is interested in, to upcall by
issuing an ipc(). The challenge here is to make sure everytime a brick
goes offline and comes back up, the ipc() needs to be issued to the
bricks. Hence ipc() is sent from md-cache every time there is a
CHILD_UP/CHILD_MODIFIED event.

TODO:
There will be patches following, in cluster xlators, to implement ipc fop.

Change-Id: I6efcf3df474f5ce6eabd3d6694c00c7bd89bc25d
BUG: 1211863
Signed-off-by: Poornima G <pgurusid@redhat.com>
Reviewed-on: http://review.gluster.org/15002
Smoke: Gluster Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Rajesh Joseph <rjoseph@redhat.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Prashanth Pai <ppai@redhat.com>
Reviewed-by: Raghavendra G <rgowdapp@redhat.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/libglusterfs/src/dict.c b/libglusterfs/src/dict.c
index 6f7adb51589..96cb9e94bda 100644
--- a/libglusterfs/src/dict.c
+++ b/libglusterfs/src/dict.c
@@ -473,6 +473,26 @@ dict_get (dict_t *this, char *key)
         return NULL;
 }
 
+int
+dict_key_count (dict_t *this)
+{
+        int ret = -1;
+
+        if (!this) {
+                gf_msg_callingfn ("dict", GF_LOG_WARNING, EINVAL,
+                                  LG_MSG_INVALID_ARG, "dict passed is NULL");
+                return ret;
+        }
+
+        LOCK (&this->lock);
+        {
+                ret = this->count;
+        }
+        UNLOCK (&this->lock);
+
+        return ret;
+}
+
 void
 dict_del (dict_t *this, char *key)
 {