xfs: improve rt metadata use for scrub

This short series makes some small changes to the way we handle the
realtime metadata inodes.  First, we now make sure that the bitmap and
summary file forks are always loaded at mount time so that every
scrubber won't have to call xfs_iread_extents.  This won't be easy if
we're, say, cross-referencing realtime space allocations.  The second
change makes the ILOCK annotations more consistent with the rest of XFS.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
-----BEGIN PGP SIGNATURE-----
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=hpdT
-----END PGP SIGNATURE-----