diff options
| -rw-r--r-- | drivers/md/dm-cache-policy-cleaner.c | 3 | ||||
| -rw-r--r-- | drivers/md/dm-cache-policy-internal.h | 5 | ||||
| -rw-r--r-- | drivers/md/dm-cache-policy-mq.c | 41 | ||||
| -rw-r--r-- | drivers/md/dm-cache-policy.h | 15 | ||||
| -rw-r--r-- | drivers/md/dm-cache-target.c | 58 |
5 files changed, 85 insertions, 37 deletions
diff --git a/drivers/md/dm-cache-policy-cleaner.c b/drivers/md/dm-cache-policy-cleaner.c index b04d1f9..004e463 100644 --- a/drivers/md/dm-cache-policy-cleaner.c +++ b/drivers/md/dm-cache-policy-cleaner.c @@ -171,7 +171,8 @@ static void remove_cache_hash_entry(struct wb_cache_entry *e) /* Public interface (see dm-cache-policy.h */ static int wb_map(struct dm_cache_policy *pe, 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) { struct policy *p = to_policy(pe); struct wb_cache_entry *e; diff --git a/drivers/md/dm-cache-policy-internal.h b/drivers/md/dm-cache-policy-internal.h index 2256a1f..c198e6d 100644 --- a/drivers/md/dm-cache-policy-internal.h +++ b/drivers/md/dm-cache-policy-internal.h @@ -16,9 +16,10 @@ */ static inline int policy_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) { - return p->map(p, oblock, can_block, can_migrate, discarded_oblock, bio, result); + return p->map(p, oblock, can_block, can_migrate, discarded_oblock, bio, locker, result); } static inline int policy_lookup(struct dm_cache_policy *p, dm_oblock_t oblock, dm_cblock_t *cblock) diff --git a/drivers/md/dm-cache-policy-mq.c b/drivers/md/dm-cache-policy-mq.c index 3ddd116..515d44b 100644 --- a/drivers/md/dm-cache-policy-mq.c +++ b/drivers/md/dm-cache-policy-mq.c @@ -693,9 +693,10 @@ static void requeue(struct mq_policy *mq, struct entry *e) * - set the hit count to a hard coded value other than 1, eg, is it better * if it goes in at level 2? */ -static int demote_cblock(struct mq_policy *mq, dm_oblock_t *oblock) +static int demote_cblock(struct mq_policy *mq, + struct policy_locker *locker, dm_oblock_t *oblock) { - struct entry *demoted = pop(mq, &mq->cache_clean); + struct entry *demoted = peek(&mq->cache_clean); if (!demoted) /* @@ -707,6 +708,13 @@ static int demote_cblock(struct mq_policy *mq, dm_oblock_t *oblock) */ return -ENOSPC; + if (locker->fn(locker, demoted->oblock)) + /* + * We couldn't lock the demoted block. + */ + return -EBUSY; + + del(mq, demoted); *oblock = demoted->oblock; free_entry(&mq->cache_pool, demoted); @@ -795,6 +803,7 @@ static int cache_entry_found(struct mq_policy *mq, * finding which cache block to use. */ static int pre_cache_to_cache(struct mq_policy *mq, struct entry *e, + struct policy_locker *locker, struct policy_result *result) { int r; @@ -803,11 +812,12 @@ static int pre_cache_to_cache(struct mq_policy *mq, struct entry *e, /* Ensure there's a free cblock in the cache */ if (epool_empty(&mq->cache_pool)) { result->op = POLICY_REPLACE; - r = demote_cblock(mq, &result->old_oblock); + r = demote_cblock(mq, locker, &result->old_oblock); if (r) { result->op = POLICY_MISS; return 0; } + } else result->op = POLICY_NEW; @@ -829,7 +839,8 @@ static int pre_cache_to_cache(struct mq_policy *mq, struct entry *e, static int pre_cache_entry_found(struct mq_policy *mq, struct entry *e, bool can_migrate, bool discarded_oblock, - int data_dir, struct policy_result *result) + int data_dir, struct policy_locker *locker, + struct policy_result *result) { int r = 0; @@ -842,7 +853,7 @@ static int pre_cache_entry_found(struct mq_policy *mq, struct entry *e, else { requeue(mq, e); - r = pre_cache_to_cache(mq, e, result); + r = pre_cache_to_cache(mq, e, locker, result); } return r; @@ -872,6 +883,7 @@ static void insert_in_pre_cache(struct mq_policy *mq, } static void insert_in_cache(struct mq_policy *mq, dm_oblock_t oblock, + struct policy_locker *locker, struct policy_result *result) { int r; @@ -879,7 +891,7 @@ static void insert_in_cache(struct mq_policy *mq, dm_oblock_t oblock, if (epool_empty(&mq->cache_pool)) { result->op = POLICY_REPLACE; - r = demote_cblock(mq, &result->old_oblock); + r = demote_cblock(mq, locker, &result->old_oblock); if (unlikely(r)) { result->op = POLICY_MISS; insert_in_pre_cache(mq, oblock); @@ -907,11 +919,12 @@ static void insert_in_cache(struct mq_policy *mq, dm_oblock_t oblock, static int no_entry_found(struct mq_policy *mq, dm_oblock_t oblock, bool can_migrate, bool discarded_oblock, - int data_dir, struct policy_result *result) + int data_dir, struct policy_locker *locker, + struct policy_result *result) { if (adjusted_promote_threshold(mq, discarded_oblock, data_dir) <= 1) { if (can_migrate) - insert_in_cache(mq, oblock, result); + insert_in_cache(mq, oblock, locker, result); else return -EWOULDBLOCK; } else { @@ -928,7 +941,8 @@ static int no_entry_found(struct mq_policy *mq, dm_oblock_t oblock, */ static int map(struct mq_policy *mq, dm_oblock_t oblock, bool can_migrate, bool discarded_oblock, - int data_dir, struct policy_result *result) + int data_dir, struct policy_locker *locker, + struct policy_result *result) { int r = 0; struct entry *e = hash_lookup(mq, oblock); @@ -942,11 +956,11 @@ static int map(struct mq_policy *mq, dm_oblock_t oblock, else if (e) r = pre_cache_entry_found(mq, e, can_migrate, discarded_oblock, - data_dir, result); + data_dir, locker, result); else r = no_entry_found(mq, oblock, can_migrate, discarded_oblock, - data_dir, result); + data_dir, locker, result); if (r == -EWOULDBLOCK) result->op = POLICY_MISS; @@ -1012,7 +1026,8 @@ static void copy_tick(struct mq_policy *mq) static int mq_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) { int r; struct mq_policy *mq = to_mq_policy(p); @@ -1028,7 +1043,7 @@ static int mq_map(struct dm_cache_policy *p, dm_oblock_t oblock, iot_examine_bio(&mq->tracker, bio); r = map(mq, oblock, can_migrate, discarded_oblock, - bio_data_dir(bio), result); + bio_data_dir(bio), locker, result); mutex_unlock(&mq->lock); diff --git a/drivers/md/dm-cache-policy.h b/drivers/md/dm-cache-policy.h index f50fe36..5524e21 100644 --- a/drivers/md/dm-cache-policy.h +++ b/drivers/md/dm-cache-policy.h @@ -70,6 +70,18 @@ enum policy_operation { }; /* + * 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 @@ 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 diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index 41b2594..d598248 100644 --- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -1439,16 +1439,43 @@ static void inc_miss_counter(struct cache *cache, struct bio *bio) &cache->stats.read_miss : &cache->stats.write_miss); } +/*----------------------------------------------------------------*/ + +struct old_oblock_lock { + struct policy_locker locker; + struct cache *cache; + struct prealloc *structs; + struct dm_bio_prison_cell *cell; +}; + +static int null_locker(struct policy_locker *locker, dm_oblock_t b) +{ + /* This should never be called */ + BUG(); + return 0; +} + +static int cell_locker(struct policy_locker *locker, dm_oblock_t b) +{ + struct old_oblock_lock *l = container_of(locker, struct old_oblock_lock, locker); + struct dm_bio_prison_cell *cell_prealloc = prealloc_get_cell(l->structs); + + return bio_detain(l->cache, b, NULL, cell_prealloc, + (cell_free_fn) prealloc_put_cell, + l->structs, &l->cell); +} + static void process_bio(struct cache *cache, struct prealloc *structs, struct bio *bio) { int r; bool release_cell = true; dm_oblock_t block = get_bio_block(cache, bio); - struct dm_bio_prison_cell *cell_prealloc, *old_ocell, *new_ocell; + struct dm_bio_prison_cell *cell_prealloc, *new_ocell; struct policy_result lookup_result; bool passthrough = passthrough_mode(&cache->features); bool discarded_block, can_migrate; + struct old_oblock_lock ool; /* * Check to see if that block is currently migrating. @@ -1463,8 +1490,12 @@ static void process_bio(struct cache *cache, struct prealloc *structs, discarded_block = is_discarded_oblock(cache, block); can_migrate = !passthrough && (discarded_block || spare_migration_bandwidth(cache)); + ool.locker.fn = cell_locker; + ool.cache = cache; + ool.structs = structs; + ool.cell = NULL; r = policy_map(cache->policy, block, true, can_migrate, discarded_block, - bio, &lookup_result); + bio, &ool.locker, &lookup_result); if (r == -EWOULDBLOCK) /* migration has been denied */ @@ -1521,27 +1552,11 @@ static void process_bio(struct cache *cache, struct prealloc *structs, break; case POLICY_REPLACE: - cell_prealloc = prealloc_get_cell(structs); - r = bio_detain(cache, lookup_result.old_oblock, bio, cell_prealloc, - (cell_free_fn) prealloc_put_cell, - structs, &old_ocell); - if (r > 0) { - /* - * We have to be careful to avoid lock inversion of - * the cells. So we back off, and wait for the - * old_ocell to become free. - */ - policy_force_mapping(cache->policy, block, - lookup_result.old_oblock); - atomic_inc(&cache->stats.cache_cell_clash); - break; - } atomic_inc(&cache->stats.demotion); atomic_inc(&cache->stats.promotion); - demote_then_promote(cache, structs, lookup_result.old_oblock, block, lookup_result.cblock, - old_ocell, new_ocell); + ool.cell, new_ocell); release_cell = false; break; @@ -2589,6 +2604,9 @@ static int __cache_map(struct cache *cache, struct bio *bio, struct dm_bio_priso bool discarded_block; struct policy_result lookup_result; struct per_bio_data *pb = init_per_bio_data(bio, pb_data_size); + struct old_oblock_lock ool; + + ool.locker.fn = null_locker; if (unlikely(from_oblock(block) >= from_oblock(cache->origin_blocks))) { /* @@ -2627,7 +2645,7 @@ static int __cache_map(struct cache *cache, struct bio *bio, struct dm_bio_priso discarded_block = is_discarded_oblock(cache, block); r = policy_map(cache->policy, block, false, can_migrate, discarded_block, - bio, &lookup_result); + bio, &ool.locker, &lookup_result); if (r == -EWOULDBLOCK) { cell_defer(cache, *cell, true); return DM_MAPIO_SUBMITTED; |
