dquot recovery should add verifiers to the dquot buffers that it
recovers changes into. Unfortunately, it doesn't attached the
verifiers to the buffers in a consistent manner. For example,
xlog_recover_dquot_pass2() reads dquot buffers without a verifier
and then writes it without ever having attached a verifier to the
buffer.

Further, dquot buffer recovery may write a dquot buffer that has not
been modified, or indeed, shoul dbe written because quotas are not
enabled and hence changes to the buffer were not replayed. In this
case, we again write buffers without verifiers attached because that
doesn't happen until after the buffer changes have been replayed.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>