Using rewrite-corrupted means quorum may issue writes to its children
just from receiving read requests from its parents.  Thus, it must take
the WRITE permission when rewrite-corrupted is used.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20201113211718.261671-2-mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>