Commit ccdbf0aa authored by Damien Le Moal's avatar Damien Le Moal Committed by Jens Axboe
Browse files

block: Allow zero value of max_zone_append_sectors queue limit 



In preparation for adding a generic zone append emulation using zone
write plugging, allow device drivers supporting zoned block device to
set a the max_zone_append_sectors queue limit of a device to 0 to
indicate the lack of native support for zone append operations and that
the block layer should emulate these operations using regular write
operations.

blk_queue_max_zone_append_sectors() is modified to allow passing 0 as
the max_zone_append_sectors argument. The function
queue_max_zone_append_sectors() is also modified to ensure that the
minimum of the max_hw_sectors and chunk_sectors limit is used whenever
the max_zone_append_sectors limit is 0. This minimum is consistent with
the value set for the max_zone_append_sectors limit by the function
blk_validate_zoned_limits() when limits for a queue are validated.

The helper functions queue_emulates_zone_append() and
bdev_emulates_zone_append() are added to test if a queue (or block
device) emulates zone append operations.

In order for blk_revalidate_disk_zones() to accept zoned block devices
relying on zone append emulation, the direct check to the
max_zone_append_sectors queue limit of the disk is replaced by a check
using the value returned by queue_max_zone_append_sectors(). Similarly,
queue_zone_append_max_show() is modified to use the same accessor so
that the sysfs attribute advertizes the non-zero limit that will be
used, regardless if it is for native or emulated commands.

For stacking drivers, a top device should not need to care if the
underlying devices have native or emulated zone append operations.
blk_stack_limits() is thus modified to set the top device
max_zone_append_sectors limit using the new accessor
queue_limits_max_zone_append_sectors(). queue_max_zone_append_sectors()
is modified to use this function as well. Stacking drivers that require
zone append emulation, e.g. dm-crypt, can still request this feature by
calling blk_queue_max_zone_append_sectors() with a 0 limit.

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/20240408014128.205141-10-dlemoal@kernel.org


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 843283e9

block/blk-core.c

+1 −1
Original line number Diff line number Diff line
@@ -602,7 +602,7 @@ static inline blk_status_t blk_check_zone_append(struct request_queue *q, 
		return BLK_STS_IOERR;



	/* Make sure the BIO is small enough and will not get split */

	if (nr_sectors > q->limits.max_zone_append_sectors)

	if (nr_sectors > queue_max_zone_append_sectors(q))

		return BLK_STS_IOERR;



	bio->bi_opf |= REQ_NOMERGE;

block/blk-settings.c

+19 −11
Original line number Diff line number Diff line
@@ -412,24 +412,32 @@ EXPORT_SYMBOL(blk_queue_max_write_zeroes_sectors); 
 * blk_queue_max_zone_append_sectors - set max sectors for a single zone append

 * @q:  the request queue for the device

 * @max_zone_append_sectors: maximum number of sectors to write per command

 *

 * Sets the maximum number of sectors allowed for zone append commands. If

 * Specifying 0 for @max_zone_append_sectors indicates that the queue does

 * not natively support zone append operations and that the block layer must

 * emulate these operations using regular writes.

 **/

void blk_queue_max_zone_append_sectors(struct request_queue *q,

		unsigned int max_zone_append_sectors)

{

	unsigned int max_sectors;

	unsigned int max_sectors = 0;



	if (WARN_ON(!blk_queue_is_zoned(q)))

		return;



	max_sectors = min(q->limits.max_hw_sectors, max_zone_append_sectors);

	if (max_zone_append_sectors) {

		max_sectors = min(q->limits.max_hw_sectors,

				  max_zone_append_sectors);

		max_sectors = min(q->limits.chunk_sectors, max_sectors);



		/*

	 * Signal eventual driver bugs resulting in the max_zone_append sectors limit

	 * being 0 due to a 0 argument, the chunk_sectors limit (zone size) not set,

	 * or the max_hw_sectors limit not set.

		 * Signal eventual driver bugs resulting in the max_zone_append

		 * sectors limit being 0 due to the chunk_sectors limit (zone

		 * size) not set or the max_hw_sectors limit not set.

		 */

	WARN_ON(!max_sectors);

		WARN_ON_ONCE(!max_sectors);

	}



	q->limits.max_zone_append_sectors = max_sectors;

}
@@ -756,8 +764,8 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, 
	t->max_dev_sectors = min_not_zero(t->max_dev_sectors, b->max_dev_sectors);

	t->max_write_zeroes_sectors = min(t->max_write_zeroes_sectors,

					b->max_write_zeroes_sectors);

	t->max_zone_append_sectors = min(t->max_zone_append_sectors,

					b->max_zone_append_sectors);

	t->max_zone_append_sectors = min(queue_limits_max_zone_append_sectors(t),

					 queue_limits_max_zone_append_sectors(b));

	t->bounce = max(t->bounce, b->bounce);



	t->seg_boundary_mask = min_not_zero(t->seg_boundary_mask,

block/blk-sysfs.c

+1 −1
Original line number Diff line number Diff line
@@ -224,7 +224,7 @@ static ssize_t queue_zone_write_granularity_show(struct request_queue *q, 


static ssize_t queue_zone_append_max_show(struct request_queue *q, char *page)

{

	unsigned long long max_sectors = q->limits.max_zone_append_sectors;

	unsigned long long max_sectors = queue_max_zone_append_sectors(q);



	return sprintf(page, "%llu\n", max_sectors << SECTOR_SHIFT);

}

block/blk-zoned.c

+1 −1
Original line number Diff line number Diff line
@@ -1692,7 +1692,7 @@ int blk_revalidate_disk_zones(struct gendisk *disk, 
		return -ENODEV;

	}



	if (!q->limits.max_zone_append_sectors) {

	if (!queue_max_zone_append_sectors(q)) {

		pr_warn("%s: Invalid 0 maximum zone append limit\n",

			disk->disk_name);

		return -ENODEV;

include/linux/blkdev.h

+20 −3
Original line number Diff line number Diff line
@@ -1173,12 +1173,29 @@ static inline unsigned int queue_max_segment_size(const struct request_queue *q) 
	return q->limits.max_segment_size;

}



static inline unsigned int queue_max_zone_append_sectors(const struct request_queue *q)

static inline unsigned int queue_limits_max_zone_append_sectors(struct queue_limits *l)

{

	unsigned int max_sectors = min(l->chunk_sectors, l->max_hw_sectors);



	const struct queue_limits *l = &q->limits;

	return min_not_zero(l->max_zone_append_sectors, max_sectors);

}



static inline unsigned int queue_max_zone_append_sectors(struct request_queue *q)

{

	if (!blk_queue_is_zoned(q))

		return 0;



	return min(l->max_zone_append_sectors, l->max_sectors);

	return queue_limits_max_zone_append_sectors(&q->limits);

}



static inline bool queue_emulates_zone_append(struct request_queue *q)

{

	return blk_queue_is_zoned(q) && !q->limits.max_zone_append_sectors;

}



static inline bool bdev_emulates_zone_append(struct block_device *bdev)

{

	return queue_emulates_zone_append(bdev_get_queue(bdev));

}



static inline unsigned int