dm cache: speed up writing of the hint array
It's far quicker to always delete the hint array and recreate with
dm_array_new() because we avoid the copying caused by mutation.
Also simplifies the policy interface, replacing the walk_hints() with
the simpler get_hint().
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-cache-policy.h b/drivers/md/dm-cache-policy.h
index 05db56e..aa10b14 100644
--- a/drivers/md/dm-cache-policy.h
+++ b/drivers/md/dm-cache-policy.h
@@ -90,9 +90,6 @@
dm_cblock_t cblock; /* POLICY_HIT, POLICY_NEW, POLICY_REPLACE */
};
-typedef int (*policy_walk_fn)(void *context, dm_cblock_t cblock,
- dm_oblock_t oblock, uint32_t hint);
-
/*
* The cache policy object. Just a bunch of methods. It is envisaged that
* this structure will be embedded in a bigger, policy specific structure
@@ -158,8 +155,11 @@
int (*load_mapping)(struct dm_cache_policy *p, dm_oblock_t oblock,
dm_cblock_t cblock, uint32_t hint, bool hint_valid);
- int (*walk_mappings)(struct dm_cache_policy *p, policy_walk_fn fn,
- void *context);
+ /*
+ * Gets the hint for a given cblock. Called in a single threaded
+ * context. So no locking required.
+ */
+ uint32_t (*get_hint)(struct dm_cache_policy *p, dm_cblock_t cblock);
/*
* Override functions used on the error paths of the core target.