Synchronization of collision table

Adding synchronization around metadata collision segment pages.
This part of metadata is modified when cacheline is mapped/unmapped
and when dirty status changes.

Synchronization on page level is required on top of cacheline
and hash bucket locks to assure metadata flush always reads
consistent state when copying entire collision table memory
page.

Signed-off-by: Adam Rutkowski <adam.j.rutkowski@intel.com>

src/engine/engine_common.c

@@ -260,8 +260,10 @@ static void ocf_engine_map_cache_line(struct ocf_request *req,
 	ocf_metadata_add_to_partition(cache, part_id, *cache_line);
 
 	/* Add the block to the corresponding collision list */
+	ocf_metadata_start_collision_shared_access(cache, *cache_line);
 	ocf_metadata_add_to_collision(cache, core_id, core_line, hash_index,
 			*cache_line);
+	ocf_metadata_end_collision_shared_access(cache, *cache_line);
 
 	ocf_eviction_init_cache_line(cache, *cache_line, part_id);
 
@@ -295,9 +297,17 @@ static void ocf_engine_map_hndl_error(struct ocf_cache *cache,
 		case LOOKUP_MAPPED:
 			OCF_DEBUG_RQ(req, "Canceling cache line %u",
 					entry->coll_idx);
+
+			ocf_metadata_start_collision_shared_access(cache,
+					entry->coll_idx);
+
 			set_cache_line_invalid_no_flush(cache, 0,
 					ocf_line_end_sector(cache),
 					entry->coll_idx);
+
+			ocf_metadata_end_collision_shared_access(cache,
+					entry->coll_idx);
+
 			break;
 
 		default: