Description of problem:
gluster snapshot delete volume <volname>
          (or)
gluster snapshot delete all

The above two commands might fail if some operation which acquires the
lock comes in between.

Explanation :
snapshot delete volume <volname> does a multiple RPC when tried to
do deletion of multiple snapshots in a volume. If some other operation
which acquires the lock comes in between, then snapshot delete will fail
with "another transaction in progress" error.


Version-Release number of selected component (if applicable):


How reproducible:
1/1


Steps to Reproduce:
1. issue a snapshot delete volume <volname> (say volname is vol1)
2. when step (1) is in progress, issue another command which takes a lock on volume vol1

Actual results:
snapshot delete fails with another transaction in progress.

Expected results:
command should not fail. 


Additional info:
Its better to give certain retries before failing.