From ea17fd354ca8afd3e8962a77236b1a9a59262fdd Mon Sep 17 00:00:00 2001 From: Damien Le Moal Date: Fri, 20 Nov 2020 10:55:18 +0900 Subject: [PATCH] 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: Damien Le Moal Reviewed-by: Christoph Hellwig Reviewed-by: Johannes Thumshirn Signed-off-by: Jens Axboe --- drivers/block/null_blk.h | 1 + drivers/block/null_blk_main.c | 20 +++++++++++++++++++- 2 files changed, 20 insertions(+), 1 deletion(-) diff --git a/drivers/block/null_blk.h b/drivers/block/null_blk.h index 63000ae..83504f3 100644 --- a/drivers/block/null_blk.h +++ b/drivers/block/null_blk.h @@ -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 */ diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c index b758b93..5357c3a 100644 --- a/drivers/block/null_blk_main.c +++ b/drivers/block/null_blk_main.c @@ -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; -- 2.7.4