dm cache: pass a new 'critical' flag to the policies when requesting writeback work

We only allow non critical writeback if the origin is idle.  It is up
to the policy to decide what writeback work is critical.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-cache-policy-cleaner.c b/drivers/md/dm-cache-policy-cleaner.c
index 004e463c9423cd7fe81d8f2256b63877b02aebf0..240c9f0e85e74e864624f0cb972c5b4394eaf11f 100644 (file)
--- a/drivers/md/dm-cache-policy-cleaner.c
+++ b/drivers/md/dm-cache-policy-cleaner.c
@@ -359,7 +359,8 @@ static struct wb_cache_entry *get_next_dirty_entry(struct policy *p)
 
 static int wb_writeback_work(struct dm_cache_policy *pe,
                             dm_oblock_t *oblock,
-                            dm_cblock_t *cblock)
+                            dm_cblock_t *cblock,
+                            bool critical_only)
 {
        int r = -ENOENT;
        struct policy *p = to_policy(pe);

diff --git a/drivers/md/dm-cache-policy-internal.h b/drivers/md/dm-cache-policy-internal.h
index c198e6defb9cd53009b2c61ba0dd1ae3c30d6483..776c685167e660bb6e37af9ec7a843584f54a44c 100644 (file)
--- a/drivers/md/dm-cache-policy-internal.h
+++ b/drivers/md/dm-cache-policy-internal.h
@@ -55,9 +55,10 @@ static inline int policy_walk_mappings(struct dm_cache_policy *p,
 
 static inline int policy_writeback_work(struct dm_cache_policy *p,
                                        dm_oblock_t *oblock,
-                                       dm_cblock_t *cblock)
+                                       dm_cblock_t *cblock,
+                                       bool critical_only)
 {
-       return p->writeback_work ? p->writeback_work(p, oblock, cblock) : -ENOENT;
+       return p->writeback_work ? p->writeback_work(p, oblock, cblock, critical_only) : -ENOENT;
 }
 
 static inline void policy_remove_mapping(struct dm_cache_policy *p, dm_oblock_t oblock)

diff --git a/drivers/md/dm-cache-policy-mq.c b/drivers/md/dm-cache-policy-mq.c
index 515d44bf24d3de874a3a58f521de7446710c4527..7cbae125879c7079bc87c7fb3d96ea13462a782e 100644 (file)
--- a/drivers/md/dm-cache-policy-mq.c
+++ b/drivers/md/dm-cache-policy-mq.c
@@ -1236,7 +1236,7 @@ static int __mq_writeback_work(struct mq_policy *mq, dm_oblock_t *oblock,
 }
 
 static int mq_writeback_work(struct dm_cache_policy *p, dm_oblock_t *oblock,
-                            dm_cblock_t *cblock)
+                            dm_cblock_t *cblock, bool critical_only)
 {
        int r;
        struct mq_policy *mq = to_mq_policy(p);

diff --git a/drivers/md/dm-cache-policy.h b/drivers/md/dm-cache-policy.h
index 5524e21e483654d5dc44b8b8944f9404b84b0292..6106ca3aa350a62326558e61c296e801b9fbe12b 100644 (file)
--- a/drivers/md/dm-cache-policy.h
+++ b/drivers/md/dm-cache-policy.h
@@ -178,7 +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:
         *
@@ -186,7 +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?

diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 940c7b2b5ab44163bef02d094f02b9971a0d0175..5a9cd2c5a359f64d7fea598747f26251558ea4d9 100644 (file)
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -1787,6 +1787,7 @@ static void writeback_some_dirty_blocks(struct cache *cache)
        dm_cblock_t cblock;
        struct prealloc structs;
        struct dm_bio_prison_cell *old_ocell;
+       bool busy = !iot_idle_for(&cache->origin_tracker, HZ);
 
        memset(&structs, 0, sizeof(structs));
 
@@ -1794,7 +1795,7 @@ static void writeback_some_dirty_blocks(struct cache *cache)
                if (prealloc_data_structs(cache, &structs))
                        break;
 
-               r = policy_writeback_work(cache->policy, &oblock, &cblock);
+               r = policy_writeback_work(cache->policy, &oblock, &cblock, busy);
                if (r)
                        break;