dquot_transfer() acquires own references to dquots via dqget(). Thus it waits
for dq_lock which creates a lock inversion because dq_lock ranks above
transaction start but transaction is already started in ocfs2_setattr(). Fix
the problem by passing own references directly to __dquot_transfer.
Acked-by: Joel Becker <Joel.Becker@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>