Commit 65790ff9 authored by Joe Thornber's avatar Joe Thornber Committed by Mike Snitzer

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