dm cache: add cache block invalidation support
Cache block invalidation is removing an entry from the cache without writing it back. Cache blocks can be invalidated via the 'invalidate_cblocks' message, which takes an arbitrary number of cblock ranges: invalidate_cblocks [<cblock>|<cblock begin>-<cblock end>]* E.g. dmsetup message my_cache 0 invalidate_cblocks 2345 3456-4567 5678-6789 Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Joe Thornber
Mike Snitzer
parent
532906aa7f
commit
65790ff919
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@ -244,12 +244,22 @@ The message format is:
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E.g.
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dmsetup message my_cache 0 sequential_threshold 1024
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Invalidation is removing an entry from the cache without writing it
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back. Cache blocks can be invalidated via the invalidate_cblocks
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message, which takes an arbitrary number of cblock ranges.
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invalidate_cblocks [<cblock>|<cblock begin>-<cblock end>]*
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E.g.
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dmsetup message my_cache 0 invalidate_cblocks 2345 3456-4567 5678-6789
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Examples
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========
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The test suite can be found here:
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https://github.com/jthornber/thinp-test-suite
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https://github.com/jthornber/device-mapper-test-suite
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dmsetup create my_cache --table '0 41943040 cache /dev/mapper/metadata \
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/dev/mapper/ssd /dev/mapper/origin 512 1 writeback default 0'
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@ -150,6 +150,25 @@ struct cache_stats {
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atomic_t discard_count;
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};
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/*
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* Defines a range of cblocks, begin to (end - 1) are in the range. end is
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* the one-past-the-end value.
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*/
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struct cblock_range {
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dm_cblock_t begin;
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dm_cblock_t end;
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};
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struct invalidation_request {
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struct list_head list;
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struct cblock_range *cblocks;
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atomic_t complete;
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int err;
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wait_queue_head_t result_wait;
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};
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struct cache {
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struct dm_target *ti;
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struct dm_target_callbacks callbacks;
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@ -241,6 +260,7 @@ struct cache {
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bool need_tick_bio:1;
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bool sized:1;
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bool invalidate:1;
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bool commit_requested:1;
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bool loaded_mappings:1;
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bool loaded_discards:1;
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@ -251,6 +271,12 @@ struct cache {
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struct cache_features features;
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struct cache_stats stats;
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/*
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* Invalidation fields.
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*/
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spinlock_t invalidation_lock;
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struct list_head invalidation_requests;
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};
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struct per_bio_data {
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@ -283,6 +309,7 @@ struct dm_cache_migration {
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bool demote:1;
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bool promote:1;
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bool requeue_holder:1;
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bool invalidate:1;
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struct dm_bio_prison_cell *old_ocell;
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struct dm_bio_prison_cell *new_ocell;
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@ -904,8 +931,11 @@ static void migration_success_post_commit(struct dm_cache_migration *mg)
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list_add_tail(&mg->list, &cache->quiesced_migrations);
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spin_unlock_irqrestore(&cache->lock, flags);
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} else
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} else {
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if (mg->invalidate)
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policy_remove_mapping(cache->policy, mg->old_oblock);
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cleanup_migration(mg);
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}
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} else {
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if (mg->requeue_holder)
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@ -1115,6 +1145,7 @@ static void promote(struct cache *cache, struct prealloc *structs,
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mg->demote = false;
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mg->promote = true;
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mg->requeue_holder = true;
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mg->invalidate = false;
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mg->cache = cache;
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mg->new_oblock = oblock;
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mg->cblock = cblock;
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@ -1137,6 +1168,7 @@ static void writeback(struct cache *cache, struct prealloc *structs,
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mg->demote = false;
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mg->promote = false;
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mg->requeue_holder = true;
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mg->invalidate = false;
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mg->cache = cache;
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mg->old_oblock = oblock;
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mg->cblock = cblock;
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@ -1161,6 +1193,7 @@ static void demote_then_promote(struct cache *cache, struct prealloc *structs,
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mg->demote = true;
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mg->promote = true;
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mg->requeue_holder = true;
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mg->invalidate = false;
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mg->cache = cache;
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mg->old_oblock = old_oblock;
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mg->new_oblock = new_oblock;
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@ -1188,6 +1221,7 @@ static void invalidate(struct cache *cache, struct prealloc *structs,
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mg->demote = true;
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mg->promote = false;
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mg->requeue_holder = true;
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mg->invalidate = true;
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mg->cache = cache;
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mg->old_oblock = oblock;
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mg->cblock = cblock;
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@ -1524,6 +1558,58 @@ static void writeback_some_dirty_blocks(struct cache *cache)
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prealloc_free_structs(cache, &structs);
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}
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/*----------------------------------------------------------------
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* Invalidations.
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* Dropping something from the cache *without* writing back.
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*--------------------------------------------------------------*/
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static void process_invalidation_request(struct cache *cache, struct invalidation_request *req)
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{
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int r = 0;
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uint64_t begin = from_cblock(req->cblocks->begin);
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uint64_t end = from_cblock(req->cblocks->end);
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while (begin != end) {
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r = policy_remove_cblock(cache->policy, to_cblock(begin));
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if (!r) {
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r = dm_cache_remove_mapping(cache->cmd, to_cblock(begin));
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if (r)
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break;
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} else if (r == -ENODATA) {
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/* harmless, already unmapped */
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r = 0;
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} else {
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DMERR("policy_remove_cblock failed");
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break;
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}
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begin++;
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}
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cache->commit_requested = true;
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req->err = r;
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atomic_set(&req->complete, 1);
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wake_up(&req->result_wait);
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}
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static void process_invalidation_requests(struct cache *cache)
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{
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struct list_head list;
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struct invalidation_request *req, *tmp;
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INIT_LIST_HEAD(&list);
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spin_lock(&cache->invalidation_lock);
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list_splice_init(&cache->invalidation_requests, &list);
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spin_unlock(&cache->invalidation_lock);
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list_for_each_entry_safe (req, tmp, &list, list)
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process_invalidation_request(cache, req);
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}
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/*----------------------------------------------------------------
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* Main worker loop
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*--------------------------------------------------------------*/
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@ -1593,7 +1679,8 @@ static int more_work(struct cache *cache)
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!bio_list_empty(&cache->deferred_writethrough_bios) ||
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!list_empty(&cache->quiesced_migrations) ||
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!list_empty(&cache->completed_migrations) ||
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!list_empty(&cache->need_commit_migrations);
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!list_empty(&cache->need_commit_migrations) ||
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cache->invalidate;
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}
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static void do_worker(struct work_struct *ws)
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@ -1605,6 +1692,7 @@ static void do_worker(struct work_struct *ws)
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writeback_some_dirty_blocks(cache);
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process_deferred_writethrough_bios(cache);
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process_deferred_bios(cache);
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process_invalidation_requests(cache);
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}
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process_migrations(cache, &cache->quiesced_migrations, issue_copy);
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@ -2271,6 +2359,7 @@ static int cache_create(struct cache_args *ca, struct cache **result)
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cache->need_tick_bio = true;
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cache->sized = false;
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cache->invalidate = false;
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cache->commit_requested = false;
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cache->loaded_mappings = false;
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cache->loaded_discards = false;
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@ -2284,6 +2373,9 @@ static int cache_create(struct cache_args *ca, struct cache **result)
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atomic_set(&cache->stats.commit_count, 0);
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atomic_set(&cache->stats.discard_count, 0);
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spin_lock_init(&cache->invalidation_lock);
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INIT_LIST_HEAD(&cache->invalidation_requests);
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*result = cache;
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return 0;
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@ -2833,7 +2925,128 @@ err:
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}
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/*
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* Supports <key> <value>.
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* A cache block range can take two forms:
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*
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* i) A single cblock, eg. '3456'
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* ii) A begin and end cblock with dots between, eg. 123-234
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*/
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static int parse_cblock_range(struct cache *cache, const char *str,
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struct cblock_range *result)
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{
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char dummy;
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uint64_t b, e;
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int r;
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/*
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* Try and parse form (ii) first.
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*/
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r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy);
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if (r < 0)
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return r;
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if (r == 2) {
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result->begin = to_cblock(b);
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result->end = to_cblock(e);
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return 0;
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}
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/*
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* That didn't work, try form (i).
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*/
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r = sscanf(str, "%llu%c", &b, &dummy);
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if (r < 0)
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return r;
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if (r == 1) {
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result->begin = to_cblock(b);
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result->end = to_cblock(from_cblock(result->begin) + 1u);
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return 0;
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}
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DMERR("invalid cblock range '%s'", str);
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return -EINVAL;
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}
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static int validate_cblock_range(struct cache *cache, struct cblock_range *range)
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{
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uint64_t b = from_cblock(range->begin);
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uint64_t e = from_cblock(range->end);
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uint64_t n = from_cblock(cache->cache_size);
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if (b >= n) {
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DMERR("begin cblock out of range: %llu >= %llu", b, n);
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return -EINVAL;
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}
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if (e > n) {
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DMERR("end cblock out of range: %llu > %llu", e, n);
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return -EINVAL;
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}
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if (b >= e) {
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DMERR("invalid cblock range: %llu >= %llu", b, e);
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return -EINVAL;
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}
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return 0;
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}
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static int request_invalidation(struct cache *cache, struct cblock_range *range)
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{
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struct invalidation_request req;
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INIT_LIST_HEAD(&req.list);
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req.cblocks = range;
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atomic_set(&req.complete, 0);
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req.err = 0;
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init_waitqueue_head(&req.result_wait);
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spin_lock(&cache->invalidation_lock);
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list_add(&req.list, &cache->invalidation_requests);
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spin_unlock(&cache->invalidation_lock);
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wake_worker(cache);
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wait_event(req.result_wait, atomic_read(&req.complete));
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return req.err;
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}
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static int process_invalidate_cblocks_message(struct cache *cache, unsigned count,
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const char **cblock_ranges)
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{
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int r = 0;
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unsigned i;
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struct cblock_range range;
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if (!passthrough_mode(&cache->features)) {
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DMERR("cache has to be in passthrough mode for invalidation");
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return -EPERM;
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}
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for (i = 0; i < count; i++) {
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r = parse_cblock_range(cache, cblock_ranges[i], &range);
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if (r)
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break;
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r = validate_cblock_range(cache, &range);
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if (r)
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break;
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/*
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* Pass begin and end origin blocks to the worker and wake it.
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*/
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r = request_invalidation(cache, &range);
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if (r)
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break;
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}
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return r;
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}
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/*
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* Supports
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* "<key> <value>"
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* and
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* "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
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*
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* The key migration_threshold is supported by the cache target core.
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*/
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@ -2841,6 +3054,12 @@ static int cache_message(struct dm_target *ti, unsigned argc, char **argv)
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{
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struct cache *cache = ti->private;
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if (!argc)
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return -EINVAL;
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if (!strcmp(argv[0], "invalidate_cblocks"))
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return process_invalidate_cblocks_message(cache, argc - 1, (const char **) argv + 1);
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if (argc != 2)
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return -EINVAL;
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