tree a5d94b86cf1eb759bfef5761015135d747e80561
parent 742c8fdc31e820503f9267070311d894978d1349
author Joe Thornber <ejt@redhat.com> 1481795851 -0500
committer Mike Snitzer <snitzer@redhat.com> 1488911311 -0500

dm cache: significant rework to leverage dm-bio-prison-v2

The cache policy interfaces have been updated to work well with the new
bio-prison v2 interface's ability to queue work immediately (promotion,
demotion, etc) -- overriding benefit being reduced latency on processing
IO through the cache.  Previously such work would be left for the DM
cache core to queue on various lists and then process in batches later
-- this caused a serious delay in latency for IO driven by the cache.

The background tracker code was factored out so that all cache policies
can make use of it.

Also, the "cleaner" policy has been removed and is now a variant of the
smq policy that simply disallows migrations.

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