This function is only used by the iomap code, depends on being called
from it, and will soon stop poking into buffer head internals.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NAndreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>