Commit 20f6814b authored by Joe Thornber's avatar Joe Thornber Committed by Mike Snitzer

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: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 066dbaa3
...@@ -359,7 +359,8 @@ static struct wb_cache_entry *get_next_dirty_entry(struct policy *p) ...@@ -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, static int wb_writeback_work(struct dm_cache_policy *pe,
dm_oblock_t *oblock, dm_oblock_t *oblock,
dm_cblock_t *cblock) dm_cblock_t *cblock,
bool critical_only)
{ {
int r = -ENOENT; int r = -ENOENT;
struct policy *p = to_policy(pe); struct policy *p = to_policy(pe);
......
...@@ -55,9 +55,10 @@ static inline int policy_walk_mappings(struct dm_cache_policy *p, ...@@ -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, static inline int policy_writeback_work(struct dm_cache_policy *p,
dm_oblock_t *oblock, 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) static inline void policy_remove_mapping(struct dm_cache_policy *p, dm_oblock_t oblock)
......
...@@ -1236,7 +1236,7 @@ static int __mq_writeback_work(struct mq_policy *mq, dm_oblock_t *oblock, ...@@ -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, 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; int r;
struct mq_policy *mq = to_mq_policy(p); struct mq_policy *mq = to_mq_policy(p);
......
...@@ -178,7 +178,9 @@ struct dm_cache_policy { ...@@ -178,7 +178,9 @@ struct dm_cache_policy {
int (*remove_cblock)(struct dm_cache_policy *p, dm_cblock_t cblock); 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: * Returns:
* *
...@@ -186,7 +188,8 @@ struct dm_cache_policy { ...@@ -186,7 +188,8 @@ struct dm_cache_policy {
* *
* -ENODATA: no dirty blocks available * -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? * How full is the cache?
......
...@@ -1787,6 +1787,7 @@ static void writeback_some_dirty_blocks(struct cache *cache) ...@@ -1787,6 +1787,7 @@ static void writeback_some_dirty_blocks(struct cache *cache)
dm_cblock_t cblock; dm_cblock_t cblock;
struct prealloc structs; struct prealloc structs;
struct dm_bio_prison_cell *old_ocell; struct dm_bio_prison_cell *old_ocell;
bool busy = !iot_idle_for(&cache->origin_tracker, HZ);
memset(&structs, 0, sizeof(structs)); memset(&structs, 0, sizeof(structs));
...@@ -1794,7 +1795,7 @@ static void writeback_some_dirty_blocks(struct cache *cache) ...@@ -1794,7 +1795,7 @@ static void writeback_some_dirty_blocks(struct cache *cache)
if (prealloc_data_structs(cache, &structs)) if (prealloc_data_structs(cache, &structs))
break; break;
r = policy_writeback_work(cache->policy, &oblock, &cblock); r = policy_writeback_work(cache->policy, &oblock, &cblock, busy);
if (r) if (r)
break; break;
......
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