cluster/afr: Avoid order mismatch in blocking entrylks

Problem:
When taking blocking entrylks, afr orders the entrylks based on
uuid_compare of gfids of parent dirs, if they are equal then it orders
them based on the basenames. While this approach works fine, the
implementation assumes loc->gfids to be populated at the time of
the comparison, but loc may have gfid in loc->inode->gfid instead
of loc->gfid which was leading to order mismatches and dead-locks.

Fix:
Implemented loc_gfid which gives gfid by checking both loc->gfid,
loc->inode->gfid. Used this for ordering the blocking entrylks.

Change-Id: Ib0db36bbaf0df09fa87c3c3bb6a834db74fc2154
BUG: 965987
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/5062
Reviewed-by: Krishnan Parthasarathi <kparthas@redhat.com>
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 13 insertions, 3 deletions

diff --git a/libglusterfs/src/xlator.c b/libglusterfs/src/xlator.c
index d8997bc7d..f9e5db671 100644
--- a/libglusterfs/src/xlator.c
+++ b/libglusterfs/src/xlator.c
@@ -618,10 +618,12 @@ out:
         return ret;
 }
 
-char*
-loc_gfid_utoa (loc_t *loc)
+void
+loc_gfid (loc_t *loc, uuid_t gfid)
 {
-        uuid_t  gfid={0};
+        if (!gfid)
+                goto out;
+        uuid_clear (gfid);
 
         if (!loc)
                 goto out;
@@ -630,6 +632,14 @@ loc_gfid_utoa (loc_t *loc)
         else if (loc->inode && (!uuid_is_null (loc->inode->gfid)))
                 uuid_copy (gfid, loc->inode->gfid);
 out:
+        return;
+}
+
+char*
+loc_gfid_utoa (loc_t *loc)
+{
+        uuid_t gfid;
+        loc_gfid (loc, gfid);
         return uuid_utoa (gfid);
 }