tree affc57a30e5db203fac2133344e29c0dad4865e5
parent 04f17c802f447e76d13ade5bb78fbbf34baef0f8
author Joe Thornber <ejt@redhat.com> 1376049896 +0100
committer Mike Snitzer <snitzer@redhat.com> 1377262934 -0400

dm space map: optimise sm_ll_dec and sm_ll_inc

Prior to this patch these methods did a lookup followed by an insert.
Instead they now call a common mutate function that adjusts the value
according to a callback function.  This avoids traversing the data
structures twice and hence improves performance.

Also factor out sm_ll_lookup_big_ref_count() for use by both
sm_ll_lookup() and sm_ll_mutate().

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>