Commit ea17fd35 authored by Damien Le Moal's avatar Damien Le Moal Committed by Jens Axboe
Browse files

null_blk: Allow controlling max_hw_sectors limit 



Add the module option and configfs attribute max_sectors to allow
configuring the maximum size of a command issued to a null_blk device.
This allows exercising the block layer BIO splitting with different
limits than the default BLK_SAFE_MAX_SECTORS. This is also useful for
testing the zone append write path of file systems as the max_hw_sectors
limit value is also used for the max_zone_append_sectors limit.

Signed-off-by: default avatarDamien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 0ec4d913

drivers/block/null_blk.h

+1 −0
Original line number Diff line number Diff line
@@ -85,6 +85,7 @@ struct nullb_device { 
	unsigned int home_node; /* home node for the device */

	unsigned int queue_mode; /* block interface */

	unsigned int blocksize; /* block size */

	unsigned int max_sectors; /* Max sectors per command */

	unsigned int irqmode; /* IRQ completion handler */

	unsigned int hw_queue_depth; /* queue depth */

	unsigned int index; /* index of the disk, only valid with a disk */

drivers/block/null_blk_main.c

+19 −1
Original line number Diff line number Diff line
@@ -152,6 +152,10 @@ static int g_bs = 512; 
module_param_named(bs, g_bs, int, 0444);

MODULE_PARM_DESC(bs, "Block size (in bytes)");



static int g_max_sectors;

module_param_named(max_sectors, g_max_sectors, int, 0444);

MODULE_PARM_DESC(max_sectors, "Maximum size of a command (in 512B sectors)");



static unsigned int nr_devices = 1;

module_param(nr_devices, uint, 0444);

MODULE_PARM_DESC(nr_devices, "Number of devices to register");
@@ -346,6 +350,7 @@ NULLB_DEVICE_ATTR(submit_queues, uint, nullb_apply_submit_queues); 
NULLB_DEVICE_ATTR(home_node, uint, NULL);

NULLB_DEVICE_ATTR(queue_mode, uint, NULL);

NULLB_DEVICE_ATTR(blocksize, uint, NULL);

NULLB_DEVICE_ATTR(max_sectors, uint, NULL);

NULLB_DEVICE_ATTR(irqmode, uint, NULL);

NULLB_DEVICE_ATTR(hw_queue_depth, uint, NULL);

NULLB_DEVICE_ATTR(index, uint, NULL);
@@ -463,6 +468,7 @@ static struct configfs_attribute *nullb_device_attrs[] = { 
	&nullb_device_attr_home_node,

	&nullb_device_attr_queue_mode,

	&nullb_device_attr_blocksize,

	&nullb_device_attr_max_sectors,

	&nullb_device_attr_irqmode,

	&nullb_device_attr_hw_queue_depth,

	&nullb_device_attr_index,
@@ -533,7 +539,7 @@ nullb_group_drop_item(struct config_group *group, struct config_item *item) 
static ssize_t memb_group_features_show(struct config_item *item, char *page)

{

	return snprintf(page, PAGE_SIZE,

			"memory_backed,discard,bandwidth,cache,badblocks,zoned,zone_size,zone_capacity,zone_nr_conv,zone_max_open,zone_max_active\n");

			"memory_backed,discard,bandwidth,cache,badblocks,zoned,zone_size,zone_capacity,zone_nr_conv,zone_max_open,zone_max_active,blocksize,max_sectors\n");

}



CONFIGFS_ATTR_RO(memb_group_, features);
@@ -588,6 +594,7 @@ static struct nullb_device *null_alloc_dev(void) 
	dev->home_node = g_home_node;

	dev->queue_mode = g_queue_mode;

	dev->blocksize = g_bs;

	dev->max_sectors = g_max_sectors;

	dev->irqmode = g_irqmode;

	dev->hw_queue_depth = g_hw_queue_depth;

	dev->blocking = g_blocking;
@@ -1867,6 +1874,11 @@ static int null_add_dev(struct nullb_device *dev) 


	blk_queue_logical_block_size(nullb->q, dev->blocksize);

	blk_queue_physical_block_size(nullb->q, dev->blocksize);

	if (!dev->max_sectors)

		dev->max_sectors = queue_max_hw_sectors(nullb->q);

	dev->max_sectors = min_t(unsigned int, dev->max_sectors,

				 BLK_DEF_MAX_SECTORS);

	blk_queue_max_hw_sectors(nullb->q, dev->max_sectors);



	null_config_discard(nullb);
@@ -1910,6 +1922,12 @@ static int __init null_init(void) 
		g_bs = PAGE_SIZE;

	}



	if (g_max_sectors > BLK_DEF_MAX_SECTORS) {

		pr_warn("invalid max sectors\n");

		pr_warn("defaults max sectors to %u\n", BLK_DEF_MAX_SECTORS);

		g_max_sectors = BLK_DEF_MAX_SECTORS;

	}



	if (g_home_node != NUMA_NO_NODE && g_home_node >= nr_online_nodes) {

		pr_err("invalid home_node value\n");

		g_home_node = NUMA_NO_NODE;

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