dm zoned: add a 'reserved' zone flag

Instead of counting the number of reserved zones in dmz_free_zone(),
mark the zone as 'reserved' during allocation and simplify
dmz_free_zone().
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

@@ -1743,6 +1743,7 @@ static int dmz_load_mapping(struct dmz_metadata *zmd)
 			atomic_inc(&zmd->unmap_nr_rnd);
 		} else if (atomic_read(&zmd->nr_reserved_seq_zones) < zmd->nr_reserved_seq) {
 			list_add_tail(&dzone->link, &zmd->reserved_seq_zones_list);
+			set_bit(DMZ_RESERVED, &dzone->flags);
 			atomic_inc(&zmd->nr_reserved_seq_zones);
 			zmd->nr_seq--;
 		} else {
@@ -2168,8 +2169,7 @@ void dmz_free_zone(struct dmz_metadata *zmd, struct dm_zone *zone)
 	} else if (dmz_is_rnd(zone)) {
 		list_add_tail(&zone->link, &zmd->unmap_rnd_list);
 		atomic_inc(&zmd->unmap_nr_rnd);
-	} else if (atomic_read(&zmd->nr_reserved_seq_zones) <
-		   zmd->nr_reserved_seq) {
+	} else if (dmz_is_reserved(zone)) {
 		list_add_tail(&zone->link, &zmd->reserved_seq_zones_list);
 		atomic_inc(&zmd->nr_reserved_seq_zones);
 	} else {

drivers/md/dm-zoned.h

@@ -123,6 +123,7 @@ enum {
 	DMZ_META,
 	DMZ_DATA,
 	DMZ_BUF,
+	DMZ_RESERVED,
 
 	/* Zone internal state */
 	DMZ_RECLAIM,
@@ -140,6 +141,7 @@ enum {
 #define dmz_is_offline(z)	test_bit(DMZ_OFFLINE, &(z)->flags)
 #define dmz_is_readonly(z)	test_bit(DMZ_READ_ONLY, &(z)->flags)
 #define dmz_in_reclaim(z)	test_bit(DMZ_RECLAIM, &(z)->flags)
+#define dmz_is_reserved(z)	test_bit(DMZ_RESERVED, &(z)->flags)
 #define dmz_seq_write_err(z)	test_bit(DMZ_SEQ_WRITE_ERR, &(z)->flags)
 #define dmz_reclaim_should_terminate(z) \
 				test_bit(DMZ_RECLAIM_TERMINATE, &(z)->flags)