dht: make lookup-unhashed=auto do something actually useful

The key concept here is to determine whether a directory is "clean" by
comparing its last-known-good topology to the current one for the
volume.  These are stored as "commit hashes" on the directory and the
volume root respectively.  The volume's commit hash changes whenever a
brick is added or removed, and a fix-layout is done.  A directory's
commit hash changes only when a full rebalance (not just fix-layout)
is done on it.  If all bricks are present and have a directory
commit hash that matches the volume commit hash, then we can assume
that every file is in its "proper" place. Therefore, if we look for
a file in that proper place and don't find it, we can assume it's not
on any other subvolume and *safely* skip the global (broadcast to all)
lookup.

Change-Id: Id6ce4593ba1f7daffa74cfab591cb45960629ae3
BUG: 1219637
Signed-off-by: Jeff Darcy <jdarcy@redhat.com>
Signed-off-by: Shyam <srangana@redhat.com>
Reviewed-on: http://review.gluster.org/7702
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Tested-by: NetBSD Build System
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/tests/bugs/distribute/bug-921408.t b/tests/bugs/distribute/bug-921408.t
index b1887f8ae2..559114bb85 100755
--- a/tests/bugs/distribute/bug-921408.t
+++ b/tests/bugs/distribute/bug-921408.t
@@ -37,7 +37,7 @@ addbr_rebal_till_layout_change()
                 then
                         break
                 fi
-                NEW_LAYOUT=`get_layout $B0/${V0}0`
+                NEW_LAYOUT=`get_layout $B0/${V0}0 | cut -c11-34`
                 if [ $OLD_LAYOUT == $NEW_LAYOUT ]
                 then
                         i=`expr $i + 1`;
@@ -64,7 +64,7 @@ TEST touch $M0/test/test
 fd=`fd_available`
 TEST fd_open $fd "rw" $M0/test/test
 
-OLD_LAYOUT=`get_layout $B0/${V0}0`
+OLD_LAYOUT=`get_layout $B0/${V0}0 | cut -c11-34`
 
 addbr_rebal_till_layout_change 1