block: introduce blk_queue_clear_zone_settings()

Introduce the internal function blk_queue_clear_zone_settings() to
cleanup all limits and resources related to zoned block devices. This
new function is called from blk_queue_set_zoned() when a disk zoned
model is set to BLK_ZONED_NONE. This particular case can happens when a
partition is created on a host-aware scsi disk.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@edc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: damien-lemoal

block/blk-settings.c

@@ -910,6 +910,8 @@ void blk_queue_set_zoned(struct gendisk *disk, enum blk_zoned_model model)
 		 */
 		blk_queue_zone_write_granularity(q,
 						queue_logical_block_size(q));
+	} else {
+		blk_queue_clear_zone_settings(q);
 	}
 }
 EXPORT_SYMBOL_GPL(blk_queue_set_zoned);

block/blk-zoned.c

@@ -549,3 +549,20 @@ int blk_revalidate_disk_zones(struct gendisk *disk,
 	return ret;
 }
 EXPORT_SYMBOL_GPL(blk_revalidate_disk_zones);
+
+void blk_queue_clear_zone_settings(struct request_queue *q)
+{
+	blk_mq_freeze_queue(q);
+
+	blk_queue_free_zone_bitmaps(q);
+	blk_queue_flag_clear(QUEUE_FLAG_ZONE_RESETALL, q);
+	q->required_elevator_features &= ~ELEVATOR_F_ZBD_SEQ_WRITE;
+	q->nr_zones = 0;
+	q->max_open_zones = 0;
+	q->max_active_zones = 0;
+	q->limits.chunk_sectors = 0;
+	q->limits.zone_write_granularity = 0;
+	q->limits.max_zone_append_sectors = 0;
+
+	blk_mq_unfreeze_queue(q);
+}

block/blk.h

@@ -334,8 +334,10 @@ struct bio *blk_next_bio(struct bio *bio, unsigned int nr_pages, gfp_t gfp);
 
 #ifdef CONFIG_BLK_DEV_ZONED
 void blk_queue_free_zone_bitmaps(struct request_queue *q);
+void blk_queue_clear_zone_settings(struct request_queue *q);
 #else
 static inline void blk_queue_free_zone_bitmaps(struct request_queue *q) {}
+static inline void blk_queue_clear_zone_settings(struct request_queue *q) {}
 #endif
 
 int blk_alloc_devt(struct block_device *part, dev_t *devt);