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[kvmfornfv.git] / kernel / drivers / md / dm-cache-policy.h

diff --git a/kernel/drivers/md/dm-cache-policy.h b/kernel/drivers/md/dm-cache-policy.h
index f50fe36..05db56e 100644 (file)
--- a/kernel/drivers/md/dm-cache-policy.h
+++ b/kernel/drivers/md/dm-cache-policy.h
@@ -69,6 +69,18 @@ enum policy_operation {
        POLICY_REPLACE
 };
 
+/*
+ * 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.
  */
@@ -122,7 +134,8 @@ struct dm_cache_policy {
         */
        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
@@ -165,7 +178,9 @@ struct dm_cache_policy {
        int (*remove_cblock)(struct dm_cache_policy *p, dm_cblock_t cblock);
 
        /*
-        * Provide a dirty block to be written back by the core target.
+        * 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:
         *
@@ -173,7 +188,8 @@ struct dm_cache_policy {
         *
         * -ENODATA: no dirty blocks available
         */
-       int (*writeback_work)(struct dm_cache_policy *p, dm_oblock_t *oblock, dm_cblock_t *cblock);
+       int (*writeback_work)(struct dm_cache_policy *p, dm_oblock_t *oblock, dm_cblock_t *cblock,
+                             bool critical_only);
 
        /*
         * How full is the cache?
@@ -184,16 +200,16 @@ struct dm_cache_policy {
         * 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);