xfs: clean up realtime type usage [v1.1] The realtime code uses xfs_rtblock_t and xfs_fsblock_t in a lot of places, and it's very confusing. Clean up all the type usage so that an xfs_rtblock_t is always a block within the realtime volume, an xfs_fileoff_t is always a file offset within a realtime metadata file, and an xfs_rtxnumber_t is always a rt extent within the realtime volume. v1.1: various cleanups suggested by hch With a bit of luck, this should all go splendidly. Signed-off-by: Darrick J. Wong <djwong@kernel.org>