dm cache: promotion optimisation for writes
authorJoe Thornber <ejt@redhat.com>
Thu, 31 Oct 2013 17:55:48 +0000 (13:55 -0400)
committerMike Snitzer <snitzer@redhat.com>
Sat, 9 Nov 2013 23:20:26 +0000 (18:20 -0500)
commitc9d28d5d09a0fd5f02f1321c8e18ff7d9f92270b
tree480183ffb8ce716748a319df07820f23477e3be7
parentc86c30706caa02ffe303e6b87d53ef6a077d4cca
dm cache: promotion optimisation for writes

If a write block triggers promotion and covers a whole block we can
avoid a copy.

Introduce dm_{hook,unhook}_bio to simplify saving and restoring bio
fields (bi_private is now used by overwrite).  Switch writethrough
support over to using these helpers too.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
drivers/md/dm-cache-target.c