Commit 843283e9 authored by Damien Le Moal's avatar Damien Le Moal Committed by Jens Axboe
Browse files

block: Fake max open zones limit when there is no limit 



For a zoned block device that has no limit on the number of open zones
and no limit on the number of active zones, the zone write plug mempool
is created with a size of 128 zone write plugs. For such case, set the
device max_open_zones queue limit to this value to indicate to the user
the potential performance penalty that may happen when writing
simultaneously to more zones than the mempool size.

Signed-off-by: default avatarDamien Le Moal <dlemoal@kernel.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Reviewed-by: default avatarBart Van Assche <bvanassche@acm.org>
Tested-by: default avatarHans Holmberg <hans.holmberg@wdc.com>
Tested-by: default avatarDennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240408014128.205141-9-dlemoal@kernel.org


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent dd291d77

block/blk-zoned.c

+35 −6
Original line number Diff line number Diff line
@@ -1503,6 +1503,38 @@ struct blk_revalidate_zone_args { 
	sector_t	sector;

};



/*

 * Update the disk zone resources information and device queue limits.

 * The disk queue is frozen when this is executed.

 */

static int disk_update_zone_resources(struct gendisk *disk,

				      struct blk_revalidate_zone_args *args)

{

	struct request_queue *q = disk->queue;

	struct queue_limits lim;



	disk->nr_zones = args->nr_zones;

	disk->zone_capacity = args->zone_capacity;

	swap(disk->seq_zones_wlock, args->seq_zones_wlock);

	swap(disk->conv_zones_bitmap, args->conv_zones_bitmap);



	/*

	 * If the device has no limit on the maximum number of open and active

	 * zones, set its max open zone limit to the mempool size to indicate

	 * to the user that there is a potential performance impact due to

	 * dynamic zone write plug allocation when simultaneously writing to

	 * more zones than the size of the mempool.

	 */

	if (disk->zone_wplugs_pool) {

		lim = queue_limits_start_update(q);

		if (!lim.max_open_zones && !lim.max_active_zones)

			lim.max_open_zones = disk->zone_wplugs_pool->min_nr;

		return queue_limits_commit_update(q, &lim);

	}



	return 0;

}



/*

 * Helper function to check the validity of zones of a zoned block device.

 */
@@ -1703,17 +1735,14 @@ int blk_revalidate_disk_zones(struct gendisk *disk, 
	 */

	blk_mq_freeze_queue(q);

	if (ret > 0) {

		disk->nr_zones = args.nr_zones;

		disk->zone_capacity = args.zone_capacity;

		swap(disk->seq_zones_wlock, args.seq_zones_wlock);

		swap(disk->conv_zones_bitmap, args.conv_zones_bitmap);

		ret = disk_update_zone_resources(disk, &args);

		if (update_driver_data)

			update_driver_data(disk);

		ret = 0;

	} else {

		pr_warn("%s: failed to revalidate zones\n", disk->disk_name);

		disk_free_zone_resources(disk);

	}

	if (ret)

		disk_free_zone_resources(disk);

	blk_mq_unfreeze_queue(q);



	kfree(args.seq_zones_wlock);