block/blk-cgroup.c: free per-blkcg data when freeing the blkcg
block/blk-cgroup.c: free per-blkcg data when freeing the blkcg

Currently, per-blkcg data is freed each time a policy is deactivated,
that is also upon scheduler switch. However, when switching from a
scheduler implementing a policy which requires per-blkcg data to
another one, that same policy might be active on other devices, and
therefore those same per-blkcg data could be still in use.
This commit lets per-blkcg data be freed when the blkcg is freed
instead of on policy deactivation.

Signed-off-by: Arianna Avanzini <20b1b82ea87150022f6495522a9f5e355ea8b305@gmail.com>
Reported-and-tested-by: Michael Kaminsky <1c0136e1d49997c360e9751f7feb432f479c8183@cs.cmu.edu>
Fixes: e48453c3 ("block, cgroup: implement policy-specific per-blkcg data")
Signed-off-by: Jens Axboe <cd8c6775e60d6f67a6984377324e5290df3d5358@fb.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs