dm zoned: separate random and cache zones

Instead of lumping emulated zones together with random zones we
should be handling them as separate 'cache' zones. This improves
code readability and allows an easier implementation of different
cache policies.

Also add additional allocation flags, to separate the type (cache,
random, or sequential) from the purpose (eg reclaim).

Also switch the allocation policy to not use random zones as buffer
zones if cache zones are present. This avoids a performance drop when
all cache zones are used.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

1 files changed, 13 insertions, 6 deletions

diff --git a/drivers/md/dm-zoned-target.c b/drivers/md/dm-zoned-target.c
index b586fc67d931..2770e293a97b 100644
--- a/drivers/md/dm-zoned-target.c
+++ b/drivers/md/dm-zoned-target.c
@@ -190,7 +190,8 @@ static int dmz_handle_read(struct dmz_target *dmz, struct dm_zone *zone,
 	DMDEBUG("(%s): READ chunk %llu -> %s zone %u, block %llu, %u blocks",
 		dmz_metadata_label(zmd),
 		(unsigned long long)dmz_bio_chunk(zmd, bio),
-		(dmz_is_rnd(zone) ? "RND" : "SEQ"),
+		(dmz_is_rnd(zone) ? "RND" :
+		 (dmz_is_cache(zone) ? "CACHE" : "SEQ")),
 		zone->id,
 		(unsigned long long)chunk_block, nr_blocks);
 
@@ -198,7 +199,8 @@ static int dmz_handle_read(struct dmz_target *dmz, struct dm_zone *zone,
 	bzone = zone->bzone;
 	while (chunk_block < end_block) {
 		nr_blocks = 0;
-		if (dmz_is_rnd(zone) || chunk_block < zone->wp_block) {
+		if (dmz_is_rnd(zone) || dmz_is_cache(zone) ||
+		    chunk_block < zone->wp_block) {
 			/* Test block validity in the data zone */
 			ret = dmz_block_valid(zmd, zone, chunk_block);
 			if (ret < 0)
@@ -331,11 +333,13 @@ static int dmz_handle_write(struct dmz_target *dmz, struct dm_zone *zone,
 	DMDEBUG("(%s): WRITE chunk %llu -> %s zone %u, block %llu, %u blocks",
 		dmz_metadata_label(zmd),
 		(unsigned long long)dmz_bio_chunk(zmd, bio),
-		(dmz_is_rnd(zone) ? "RND" : "SEQ"),
+		(dmz_is_rnd(zone) ? "RND" :
+		 (dmz_is_cache(zone) ? "CACHE" : "SEQ")),
 		zone->id,
 		(unsigned long long)chunk_block, nr_blocks);
 
-	if (dmz_is_rnd(zone) || chunk_block == zone->wp_block) {
+	if (dmz_is_rnd(zone) || dmz_is_cache(zone) ||
+	    chunk_block == zone->wp_block) {
 		/*
 		 * zone is a random zone or it is a sequential zone
 		 * and the BIO is aligned to the zone write pointer:
@@ -381,7 +385,8 @@ static int dmz_handle_discard(struct dmz_target *dmz, struct dm_zone *zone,
 	 * Invalidate blocks in the data zone and its
 	 * buffer zone if one is mapped.
 	 */
-	if (dmz_is_rnd(zone) || chunk_block < zone->wp_block)
+	if (dmz_is_rnd(zone) || dmz_is_cache(zone) ||
+	    chunk_block < zone->wp_block)
 		ret = dmz_invalidate_blocks(zmd, zone, chunk_block, nr_blocks);
 	if (ret == 0 && zone->bzone)
 		ret = dmz_invalidate_blocks(zmd, zone->bzone,
@@ -1065,8 +1070,10 @@ static void dmz_status(struct dm_target *ti, status_type_t type,
 
 	switch (type) {
 	case STATUSTYPE_INFO:
-		DMEMIT("%u zones %u/%u random %u/%u sequential",
+		DMEMIT("%u zones %u/%u cache %u/%u random %u/%u sequential",
 		       dmz_nr_zones(dmz->metadata),
+		       dmz_nr_unmap_cache_zones(dmz->metadata),
+		       dmz_nr_cache_zones(dmz->metadata),
 		       dmz_nr_unmap_rnd_zones(dmz->metadata),
 		       dmz_nr_rnd_zones(dmz->metadata),
 		       dmz_nr_unmap_seq_zones(dmz->metadata),