tree 9cfe1ba112421a7b18515d7854836a1b76aacb0b
parent b61d9509628fea995196a96b4c1713fa67dade88
author Joe Thornber <ejt@redhat.com> 1432891256 +0100
committer Mike Snitzer <snitzer@redhat.com> 1434057181 -0400

dm cache: age and write back cache entries even without active IO

The policy tick() method is normally called from interrupt context.
Both the mq and smq policies do some bottom half work for the tick
method in their map functions.  However if no IO is going through the
cache, then that bottom half work doesn't occur.  With these policies
this means recently hit entries do not age and do not get written
back as early as we'd like.

Fix this by introducing a new 'can_block' parameter to the tick()
method.  When this is set the bottom half work occurs immediately.
'can_block' is set when the tick method is called every second by the
core target (not in interrupt context).

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