dm zoned: allocate zone by device index

When allocating a zone, pass in an indicator on which device the zone
should be allocated; this increases performance for a multi-device
setup because reclaim will now allocate zones on the device for which
reclaim is running.
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>

drivers/md/dm-zoned-metadata.c

@@ -2050,7 +2050,7 @@ struct dm_zone *dmz_get_chunk_mapping(struct dmz_metadata *zmd, unsigned int chu
 			goto out;
 
 		/* Allocate a random zone */
-		dzone = dmz_alloc_zone(zmd, alloc_flags);
+		dzone = dmz_alloc_zone(zmd, 0, alloc_flags);
 		if (!dzone) {
 			if (dmz_dev_is_dying(zmd)) {
 				dzone = ERR_PTR(-EIO);
@@ -2156,7 +2156,7 @@ struct dm_zone *dmz_get_chunk_buffer(struct dmz_metadata *zmd,
 		goto out;
 
 	/* Allocate a random zone */
-	bzone = dmz_alloc_zone(zmd, alloc_flags);
+	bzone = dmz_alloc_zone(zmd, 0, alloc_flags);
 	if (!bzone) {
 		if (dmz_dev_is_dying(zmd)) {
 			bzone = ERR_PTR(-EIO);
@@ -2187,11 +2187,12 @@ struct dm_zone *dmz_get_chunk_buffer(struct dmz_metadata *zmd,
  * Get an unmapped (free) zone.
  * This must be called with the mapping lock held.
  */
-struct dm_zone *dmz_alloc_zone(struct dmz_metadata *zmd, unsigned long flags)
+struct dm_zone *dmz_alloc_zone(struct dmz_metadata *zmd, unsigned int dev_idx,
+			       unsigned long flags)
 {
 	struct list_head *list;
 	struct dm_zone *zone;
-	unsigned int dev_idx = 0;
+	int i = 0;
 
 again:
 	if (flags & DMZ_ALLOC_CACHE)
@@ -2207,8 +2208,12 @@ struct dm_zone *dmz_alloc_zone(struct dmz_metadata *zmd, unsigned long flags)
 		 */
 		if (!(flags & DMZ_ALLOC_RECLAIM))
 			return NULL;
-		if (dev_idx < zmd->nr_devs) {
-			dev_idx++;
+		/*
+		 * Try to allocate from other devices
+		 */
+		if (i < zmd->nr_devs) {
+			dev_idx = (dev_idx + 1) % zmd->nr_devs;
+			i++;
 			goto again;
 		}
 

drivers/md/dm-zoned-reclaim.c

@@ -288,7 +288,8 @@ static int dmz_reclaim_rnd_data(struct dmz_reclaim *zrc, struct dm_zone *dzone)
 	/* Get a free random or sequential zone */
 	dmz_lock_map(zmd);
 again:
-	szone = dmz_alloc_zone(zmd, alloc_flags | DMZ_ALLOC_RECLAIM);
+	szone = dmz_alloc_zone(zmd, zrc->dev_idx,
+			       alloc_flags | DMZ_ALLOC_RECLAIM);
 	if (!szone && alloc_flags == DMZ_ALLOC_SEQ && dmz_nr_cache_zones(zmd)) {
 		alloc_flags = DMZ_ALLOC_RND;
 		goto again;

drivers/md/dm-zoned.h

@@ -214,7 +214,8 @@ bool dmz_dev_is_dying(struct dmz_metadata *zmd);
 #define DMZ_ALLOC_SEQ		0x04
 #define DMZ_ALLOC_RECLAIM	0x10
 
-struct dm_zone *dmz_alloc_zone(struct dmz_metadata *zmd, unsigned long flags);
+struct dm_zone *dmz_alloc_zone(struct dmz_metadata *zmd,
+			       unsigned int dev_idx, unsigned long flags);
 void dmz_free_zone(struct dmz_metadata *zmd, struct dm_zone *zone);
 
 void dmz_map_zone(struct dmz_metadata *zmd, struct dm_zone *zone,