Drop the null buffer pointer checks in all code that calls
xfs_alloc_read_agf and doesn't pass XFS_ALLOC_FLAG_TRYLOCK because
they're no longer necessary.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDave Chinner <dchinner@redhat.com>