xfs: split xfs_bmap_btalloc

Split out the nullfb case into a separate function to reduce the stack
footprint and make the code more readable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
1 file changed