dm cache: policy ignore hints if generated by different version
When reading the dm cache metadata from disk, ignore the policy hints
unless they were generated by the same major version number of the same
policy module.
The hints are considered to be private data belonging to the specific
module that generated them and there is no requirement for them to make
sense to different versions of the policy that generated them.
Policy modules are all required to work fine if no previous hints are
supplied (or if existing hints are lost).
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-cache-metadata.h b/drivers/md/dm-cache-metadata.h
index 135864e..f45cef2 100644
--- a/drivers/md/dm-cache-metadata.h
+++ b/drivers/md/dm-cache-metadata.h
@@ -89,7 +89,7 @@
dm_cblock_t cblock, bool dirty,
uint32_t hint, bool hint_valid);
int dm_cache_load_mappings(struct dm_cache_metadata *cmd,
- const char *policy_name,
+ struct dm_cache_policy *policy,
load_mapping_fn fn,
void *context);