Problem: If a fop takes lock, and completes its operation,
it waits for 1 second before releasing the lock. However,
If ec find any lock contention within this time period,
it release the lock immediately before time expires. As we
take lock on first brick, for few operations, like read, it
might happen that discovery of lock contention might take
long time and can degrades the performance.

Solution: Provide an option to enable/disable eager lock.
If eager lock is disabled, lock will be released as soon
as fop completes.

gluster v set <VOLUME NAME> disperse.eager-lock on
gluster v set <VOLUME NAME> disperse.eager-lock off

Change-Id: I000985a787eba3c190fdcd5981dfbf04e64af166
BUG: 1314649
Signed-off-by: Ashish Pandey <aspandey@redhat.com>
Reviewed-on: http://review.gluster.org/13605
Smoke: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
Tested-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
CentOS-regression: Gluster Build System <jenkins@build.gluster.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>

Now heal-info does an open() on the file being examined so that
the client at some point sees open-fd count being > 1 and releases
the eager-lock so that heal-info doesn't remain blocked forever
until IO completes.

Change-Id: Icc478098e2bc7234408728b54d8185102b3540dc
BUG: 1297695
Signed-off-by: Krutika Dhananjay <kdhananj@redhat.com>
Reviewed-on: http://review.gluster.org/13326
Reviewed-by: Ravishankar N <ravishankar@redhat.com>
Smoke: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
Tested-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.com>