This doesn't change anything for the compiler, but hch thought it would
make the code clearer.

I moved the reference counting into its own little inline.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Acked-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>