Use QLIST_INSERT_HEAD_RCU and rcu_read_lock/unlock instead of rwlocks.
Use v9fs_synth_mutex as a write-only mutex to handle concurrent writers.
Signed-off-by: NHarsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>