--- zzzz-none-000/linux-3.10.107/drivers/md/dm-cache-policy.h	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/drivers/md/dm-cache-policy.h	2021-02-04 17:41:59.000000000 +0000
@@ -70,6 +70,18 @@
 };
 
 /*
+ * When issuing a POLICY_REPLACE the policy needs to make a callback to
+ * lock the block being demoted.  This doesn't need to occur during a
+ * writeback operation since the block remains in the cache.
+ */
+struct policy_locker;
+typedef int (*policy_lock_fn)(struct policy_locker *l, dm_oblock_t oblock);
+
+struct policy_locker {
+	policy_lock_fn fn;
+};
+
+/*
  * This is the instruction passed back to the core target.
  */
 struct policy_result {
@@ -122,7 +134,8 @@
 	 */
 	int (*map)(struct dm_cache_policy *p, dm_oblock_t oblock,
 		   bool can_block, bool can_migrate, bool discarded_oblock,
-		   struct bio *bio, struct policy_result *result);
+		   struct bio *bio, struct policy_locker *locker,
+		   struct policy_result *result);
 
 	/*
 	 * Sometimes we want to see if a block is in the cache, without
@@ -135,9 +148,6 @@
 	 */
 	int (*lookup)(struct dm_cache_policy *p, dm_oblock_t oblock, dm_cblock_t *cblock);
 
-	/*
-	 * oblock must be a mapped block.  Must not block.
-	 */
 	void (*set_dirty)(struct dm_cache_policy *p, dm_oblock_t oblock);
 	void (*clear_dirty)(struct dm_cache_policy *p, dm_oblock_t oblock);
 
@@ -159,8 +169,27 @@
 	void (*force_mapping)(struct dm_cache_policy *p, dm_oblock_t current_oblock,
 			      dm_oblock_t new_oblock);
 
-	int (*writeback_work)(struct dm_cache_policy *p, dm_oblock_t *oblock, dm_cblock_t *cblock);
+	/*
+	 * This is called via the invalidate_cblocks message.  It is
+	 * possible the particular cblock has already been removed due to a
+	 * write io in passthrough mode.  In which case this should return
+	 * -ENODATA.
+	 */
+	int (*remove_cblock)(struct dm_cache_policy *p, dm_cblock_t cblock);
 
+	/*
+	 * Provide a dirty block to be written back by the core target.  If
+	 * critical_only is set then the policy should only provide work if
+	 * it urgently needs it.
+	 *
+	 * Returns:
+	 *
+	 * 0 and @cblock,@oblock: block to write back provided
+	 *
+	 * -ENODATA: no dirty blocks available
+	 */
+	int (*writeback_work)(struct dm_cache_policy *p, dm_oblock_t *oblock, dm_cblock_t *cblock,
+			      bool critical_only);
 
 	/*
 	 * How full is the cache?
@@ -171,16 +200,16 @@
 	 * Because of where we sit in the block layer, we can be asked to
 	 * map a lot of little bios that are all in the same block (no
 	 * queue merging has occurred).  To stop the policy being fooled by
-	 * these the core target sends regular tick() calls to the policy.
+	 * these, the core target sends regular tick() calls to the policy.
 	 * The policy should only count an entry as hit once per tick.
 	 */
-	void (*tick)(struct dm_cache_policy *p);
+	void (*tick)(struct dm_cache_policy *p, bool can_block);
 
 	/*
 	 * Configuration.
 	 */
-	int (*emit_config_values)(struct dm_cache_policy *p,
-				  char *result, unsigned maxlen);
+	int (*emit_config_values)(struct dm_cache_policy *p, char *result,
+				  unsigned maxlen, ssize_t *sz_ptr);
 	int (*set_config_value)(struct dm_cache_policy *p,
 				const char *key, const char *value);
 
@@ -210,6 +239,12 @@
 	unsigned version[CACHE_POLICY_VERSION_SIZE];
 
 	/*
+	 * For use by an alias dm_cache_policy_type to point to the
+	 * real dm_cache_policy_type.
+	 */
+	struct dm_cache_policy_type *real;
+
+	/*
 	 * Policies may store a hint for each each cache block.
 	 * Currently the size of this hint must be 0 or 4 bytes but we
 	 * expect to relax this in future.