xfs: fix log recovery when unknown rocompat bits are set

[ Upstream commit 74ad4693 ]

Log recovery has always run on read only mounts, even where the primary
superblock advertises unknown rocompat bits.  Due to a misunderstanding
between Eric and Darrick back in 2018, we accidentally changed the
superblock write verifier to shutdown the fs over that exact scenario.
As a result, the log cleaning that occurs at the end of the mounting
process fails if there are unknown rocompat bits set.

As we now allow writing of the superblock if there are unknown rocompat
bits set on a RO mount, we no longer want to turn off RO state to allow
log recovery to succeed on a RO mount.  Hence we also remove all the
(now unnecessary) RO state toggling from the log recovery path.

Fixes: 9e037cb7

 ("xfs: check for unknown v5 feature bits in superblock write verifier"
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Leah Rumancik <leah.rumancik@gmail.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>