Commit e4eb37cc authored by Damien Le Moal's avatar Damien Le Moal Committed by Jens Axboe
Browse files

block: Remove elevator required features 



The only elevator feature ever implemented is ELEVATOR_F_ZBD_SEQ_WRITE
for signaling that a scheduler implements zone write locking to tightly
control the dispatching order of write operations to zoned block
devices. With the removal of zone write locking support in mq-deadline
and the reliance of all block device drivers on the block layer zone
write plugging to control ordering of write operations to zones, the
elevator feature ELEVATOR_F_ZBD_SEQ_WRITE is completely unused.
Remove it, and also remove the now unused code for filtering the
possible schedulers for a block device based on required features.

Signed-off-by: default avatarDamien Le Moal <dlemoal@kernel.org>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.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/20240408014128.205141-23-dlemoal@kernel.org


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent fde02699

block/blk-settings.c

+0 −16
Original line number Diff line number Diff line
@@ -1052,22 +1052,6 @@ void blk_queue_write_cache(struct request_queue *q, bool wc, bool fua) 
}

EXPORT_SYMBOL_GPL(blk_queue_write_cache);



/**

 * blk_queue_required_elevator_features - Set a queue required elevator features

 * @q:		the request queue for the target device

 * @features:	Required elevator features OR'ed together

 *

 * Tell the block layer that for the device controlled through @q, only the

 * only elevators that can be used are those that implement at least the set of

 * features specified by @features.

 */

void blk_queue_required_elevator_features(struct request_queue *q,

					  unsigned int features)

{

	q->required_elevator_features = features;

}

EXPORT_SYMBOL_GPL(blk_queue_required_elevator_features);



/**

 * blk_queue_can_use_dma_map_merging - configure queue for merging segments.

 * @q:		the request queue for the device

block/elevator.c

+5 −41
Original line number Diff line number Diff line
@@ -83,13 +83,6 @@ bool elv_bio_merge_ok(struct request *rq, struct bio *bio) 
}

EXPORT_SYMBOL(elv_bio_merge_ok);



static inline bool elv_support_features(struct request_queue *q,

		const struct elevator_type *e)

{

	return (q->required_elevator_features & e->elevator_features) ==

		q->required_elevator_features;

}



/**

 * elevator_match - Check whether @e's name or alias matches @name

 * @e: Scheduler to test
@@ -120,7 +113,7 @@ static struct elevator_type *elevator_find_get(struct request_queue *q, 


	spin_lock(&elv_list_lock);

	e = __elevator_find(name);

	if (e && (!elv_support_features(q, e) || !elevator_tryget(e)))

	if (e && (!elevator_tryget(e)))

		e = NULL;

	spin_unlock(&elv_list_lock);

	return e;
@@ -580,34 +573,8 @@ static struct elevator_type *elevator_get_default(struct request_queue *q) 
}



/*

 * Get the first elevator providing the features required by the request queue.

 * Default to "none" if no matching elevator is found.

 */

static struct elevator_type *elevator_get_by_features(struct request_queue *q)

{

	struct elevator_type *e, *found = NULL;



	spin_lock(&elv_list_lock);



	list_for_each_entry(e, &elv_list, list) {

		if (elv_support_features(q, e)) {

			found = e;

			break;

		}

	}



	if (found && !elevator_tryget(found))

		found = NULL;



	spin_unlock(&elv_list_lock);

	return found;

}



/*

 * For a device queue that has no required features, use the default elevator

 * settings. Otherwise, use the first elevator available matching the required

 * features. If no suitable elevator is find or if the chosen elevator

 * initialization fails, fall back to the "none" elevator (no elevator).

 * Use the default elevator settings. If the chosen elevator initialization

 * fails, fall back to the "none" elevator (no elevator).

 */

void elevator_init_mq(struct request_queue *q)

{
@@ -622,10 +589,7 @@ void elevator_init_mq(struct request_queue *q) 
	if (unlikely(q->elevator))

		return;



	if (!q->required_elevator_features)

	e = elevator_get_default(q);

	else

		e = elevator_get_by_features(q);

	if (!e)

		return;
@@ -781,7 +745,7 @@ ssize_t elv_iosched_show(struct request_queue *q, char *name) 
	list_for_each_entry(e, &elv_list, list) {

		if (e == cur)

			len += sprintf(name+len, "[%s] ", e->elevator_name);

		else if (elv_support_features(q, e))

		else

			len += sprintf(name+len, "%s ", e->elevator_name);

	}

	spin_unlock(&elv_list_lock);

block/elevator.h

+0 −1
Original line number Diff line number Diff line
@@ -74,7 +74,6 @@ struct elevator_type 
	struct elv_fs_entry *elevator_attrs;

	const char *elevator_name;

	const char *elevator_alias;

	const unsigned int elevator_features;

	struct module *elevator_owner;

#ifdef CONFIG_BLK_DEBUG_FS

	const struct blk_mq_debugfs_attr *queue_debugfs_attrs;

include/linux/blkdev.h

+0 −10
Original line number Diff line number Diff line
@@ -453,8 +453,6 @@ struct request_queue { 


	atomic_t		nr_active_requests_shared_tags;



	unsigned int		required_elevator_features;



	struct blk_mq_tags	*sched_shared_tags;



	struct list_head	icq_list;
@@ -958,14 +956,6 @@ disk_alloc_independent_access_ranges(struct gendisk *disk, int nr_ia_ranges); 
void disk_set_independent_access_ranges(struct gendisk *disk,

				struct blk_independent_access_ranges *iars);



/*

 * Elevator features for blk_queue_required_elevator_features:

 */

/* Supports zoned block devices sequential write constraint */

#define ELEVATOR_F_ZBD_SEQ_WRITE	(1U << 0)



extern void blk_queue_required_elevator_features(struct request_queue *q,

						 unsigned int features);

extern bool blk_queue_can_use_dma_map_merging(struct request_queue *q,

					      struct device *dev);