linux-phytec-ti

cifs: take read lock on GlobalSMBSes_lock in is_valid_oplock_break

...rather than a write lock. It doesn't change the list so a read lock
should be sufficient.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>