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Commit 8c081b52 authored by Joe Thornber's avatar Joe Thornber Committed by Mike Snitzer
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dm cache: simplify deferred set reference count increments 



Factor out inc_and_issue and inc_ds helpers to simplify deferred set
reference count increments.  Also cleanup cache_map to consistently call
cell_defer and inc_ds when the bio is DM_MAPIO_REMAPPED.

No functional change.

Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent e5aea7b4

drivers/md/dm-cache-target.c

+77 −46
Original line number Diff line number Diff line
@@ -718,6 +718,22 @@ static int bio_triggers_commit(struct cache *cache, struct bio *bio) 
	return bio->bi_rw & (REQ_FLUSH | REQ_FUA);

}



/*

 * You must increment the deferred set whilst the prison cell is held.  To

 * encourage this, we ask for 'cell' to be passed in.

 */

static void inc_ds(struct cache *cache, struct bio *bio,

		   struct dm_bio_prison_cell *cell)

{

	size_t pb_data_size = get_per_bio_data_size(cache);

	struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);



	BUG_ON(!cell);

	BUG_ON(pb->all_io_entry);



	pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);

}



static void issue(struct cache *cache, struct bio *bio)

{

	unsigned long flags;
@@ -737,6 +753,12 @@ static void issue(struct cache *cache, struct bio *bio) 
	spin_unlock_irqrestore(&cache->lock, flags);

}



static void inc_and_issue(struct cache *cache, struct bio *bio, struct dm_bio_prison_cell *cell)

{

	inc_ds(cache, bio, cell);

	issue(cache, bio);

}



static void defer_writethrough_bio(struct cache *cache, struct bio *bio)

{

	unsigned long flags;
@@ -1015,6 +1037,11 @@ static void issue_overwrite(struct dm_cache_migration *mg, struct bio *bio) 


	dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg);

	remap_to_cache_dirty(mg->cache, bio, mg->new_oblock, mg->cblock);



	/*

	 * No need to inc_ds() here, since the cell will be held for the

	 * duration of the io.

	 */

	generic_make_request(bio);

}
@@ -1115,7 +1142,6 @@ static void check_for_quiesced_migrations(struct cache *cache, 
		return;



	INIT_LIST_HEAD(&work);

	if (pb->all_io_entry)

	dm_deferred_entry_dec(pb->all_io_entry, &work);



	if (!list_empty(&work))
@@ -1252,6 +1278,11 @@ static void process_flush_bio(struct cache *cache, struct bio *bio) 
	else

		remap_to_cache(cache, bio, 0);



	/*

	 * REQ_FLUSH is not directed at any particular block so we don't

	 * need to inc_ds().  REQ_FUA's are split into a write + REQ_FLUSH

	 * by dm-core.

	 */

	issue(cache, bio);

}
@@ -1301,15 +1332,6 @@ static void inc_miss_counter(struct cache *cache, struct bio *bio) 
		   &cache->stats.read_miss : &cache->stats.write_miss);

}



static void issue_cache_bio(struct cache *cache, struct bio *bio,

			    struct per_bio_data *pb,

			    dm_oblock_t oblock, dm_cblock_t cblock)

{

	pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);

	remap_to_cache_dirty(cache, bio, oblock, cblock);

	issue(cache, bio);

}



static void process_bio(struct cache *cache, struct prealloc *structs,

			struct bio *bio)

{
@@ -1318,8 +1340,6 @@ static void process_bio(struct cache *cache, struct prealloc *structs, 
	dm_oblock_t block = get_bio_block(cache, bio);

	struct dm_bio_prison_cell *cell_prealloc, *old_ocell, *new_ocell;

	struct policy_result lookup_result;

	size_t pb_data_size = get_per_bio_data_size(cache);

	struct per_bio_data *pb = get_per_bio_data(bio, pb_data_size);

	bool discarded_block = is_discarded_oblock(cache, block);

	bool passthrough = passthrough_mode(&cache->features);

	bool can_migrate = !passthrough && (discarded_block || spare_migration_bandwidth(cache));
@@ -1359,9 +1379,8 @@ static void process_bio(struct cache *cache, struct prealloc *structs, 


			} else {

				/* FIXME: factor out issue_origin() */

				pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);

				remap_to_origin_clear_discard(cache, bio, block);

				issue(cache, bio);

				inc_and_issue(cache, bio, new_ocell);

			}

		} else {

			inc_hit_counter(cache, bio);
@@ -1369,20 +1388,21 @@ static void process_bio(struct cache *cache, struct prealloc *structs, 
			if (bio_data_dir(bio) == WRITE &&

			    writethrough_mode(&cache->features) &&

			    !is_dirty(cache, lookup_result.cblock)) {

				pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);

				remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock);

				issue(cache, bio);

			} else

				issue_cache_bio(cache, bio, pb, block, lookup_result.cblock);

				inc_and_issue(cache, bio, new_ocell);



			} else  {

				remap_to_cache_dirty(cache, bio, block, lookup_result.cblock);

				inc_and_issue(cache, bio, new_ocell);

			}

		}



		break;



	case POLICY_MISS:

		inc_miss_counter(cache, bio);

		pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);

		remap_to_origin_clear_discard(cache, bio, block);

		issue(cache, bio);

		inc_and_issue(cache, bio, new_ocell);

		break;



	case POLICY_NEW:
@@ -1501,6 +1521,9 @@ static void process_deferred_flush_bios(struct cache *cache, bool submit_bios) 
	bio_list_init(&cache->deferred_flush_bios);

	spin_unlock_irqrestore(&cache->lock, flags);



	/*

	 * These bios have already been through inc_ds()

	 */

	while ((bio = bio_list_pop(&bios)))

		submit_bios ? generic_make_request(bio) : bio_io_error(bio);

}
@@ -1518,6 +1541,9 @@ static void process_deferred_writethrough_bios(struct cache *cache) 
	bio_list_init(&cache->deferred_writethrough_bios);

	spin_unlock_irqrestore(&cache->lock, flags);



	/*

	 * These bios have already been through inc_ds()

	 */

	while ((bio = bio_list_pop(&bios)))

		generic_make_request(bio);

}
@@ -2406,16 +2432,13 @@ static int cache_ctr(struct dm_target *ti, unsigned argc, char **argv) 
	return r;

}



static int cache_map(struct dm_target *ti, struct bio *bio)

static int __cache_map(struct cache *cache, struct bio *bio, struct dm_bio_prison_cell **cell)

{

	struct cache *cache = ti->private;



	int r;

	dm_oblock_t block = get_bio_block(cache, bio);

	size_t pb_data_size = get_per_bio_data_size(cache);

	bool can_migrate = false;

	bool discarded_block;

	struct dm_bio_prison_cell *cell;

	struct policy_result lookup_result;

	struct per_bio_data *pb = init_per_bio_data(bio, pb_data_size);
@@ -2437,15 +2460,15 @@ static int cache_map(struct dm_target *ti, struct bio *bio) 
	/*

	 * Check to see if that block is currently migrating.

	 */

	cell = alloc_prison_cell(cache);

	if (!cell) {

	*cell = alloc_prison_cell(cache);

	if (!*cell) {

		defer_bio(cache, bio);

		return DM_MAPIO_SUBMITTED;

	}



	r = bio_detain(cache, block, bio, cell,

	r = bio_detain(cache, block, bio, *cell,

		       (cell_free_fn) free_prison_cell,

		       cache, &cell);

		       cache, cell);

	if (r) {

		if (r < 0)

			defer_bio(cache, bio);
@@ -2458,11 +2481,12 @@ static int cache_map(struct dm_target *ti, struct bio *bio) 
	r = policy_map(cache->policy, block, false, can_migrate, discarded_block,

		       bio, &lookup_result);

	if (r == -EWOULDBLOCK) {

		cell_defer(cache, cell, true);

		cell_defer(cache, *cell, true);

		return DM_MAPIO_SUBMITTED;



	} else if (r) {

		DMERR_LIMIT("Unexpected return from cache replacement policy: %d", r);

		cell_defer(cache, *cell, false);

		bio_io_error(bio);

		return DM_MAPIO_SUBMITTED;

	}
@@ -2476,52 +2500,44 @@ static int cache_map(struct dm_target *ti, struct bio *bio) 
				 * We need to invalidate this block, so

				 * defer for the worker thread.

				 */

				cell_defer(cache, cell, true);

				cell_defer(cache, *cell, true);

				r = DM_MAPIO_SUBMITTED;



			} else {

				pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);

				inc_miss_counter(cache, bio);

				remap_to_origin_clear_discard(cache, bio, block);



				cell_defer(cache, cell, false);

			}



		} else {

			inc_hit_counter(cache, bio);

			pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);



			if (bio_data_dir(bio) == WRITE && writethrough_mode(&cache->features) &&

			    !is_dirty(cache, lookup_result.cblock))

				remap_to_origin_then_cache(cache, bio, block, lookup_result.cblock);

			else

				remap_to_cache_dirty(cache, bio, block, lookup_result.cblock);



			cell_defer(cache, cell, false);

		}

		break;



	case POLICY_MISS:

		inc_miss_counter(cache, bio);

		pb->all_io_entry = dm_deferred_entry_inc(cache->all_io_ds);



		if (pb->req_nr != 0) {

			/*

			 * This is a duplicate writethrough io that is no

			 * longer needed because the block has been demoted.

			 */

			bio_endio(bio, 0);

			cell_defer(cache, cell, false);

			return DM_MAPIO_SUBMITTED;

		} else {

			cell_defer(cache, *cell, false);

			r = DM_MAPIO_SUBMITTED;



		} else

			remap_to_origin_clear_discard(cache, bio, block);

			cell_defer(cache, cell, false);

		}



		break;



	default:

		DMERR_LIMIT("%s: erroring bio: unknown policy op: %u", __func__,

			    (unsigned) lookup_result.op);

		cell_defer(cache, *cell, false);

		bio_io_error(bio);

		r = DM_MAPIO_SUBMITTED;

	}
@@ -2529,6 +2545,21 @@ static int cache_map(struct dm_target *ti, struct bio *bio) 
	return r;

}



static int cache_map(struct dm_target *ti, struct bio *bio)

{

	int r;

	struct dm_bio_prison_cell *cell;

	struct cache *cache = ti->private;



	r = __cache_map(cache, bio, &cell);

	if (r == DM_MAPIO_REMAPPED) {

		inc_ds(cache, bio, cell);

		cell_defer(cache, cell, false);

	}



	return r;

}



static int cache_end_io(struct dm_target *ti, struct bio *bio, int error)

{

	struct cache *cache = ti->private;
@@ -3072,7 +3103,7 @@ static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits) 


static struct target_type cache_target = {

	.name = "cache",

	.version = {1, 4, 0},

	.version = {1, 5, 0},

	.module = THIS_MODULE,

	.ctr = cache_ctr,

	.dtr = cache_dtr,