Commit f4f84586 authored by Damien Le Moal's avatar Damien Le Moal Committed by Jens Axboe
Browse files

null_blk: Introduce fua attribute 



Add the fua configfs attribute and module parameter to allow
configuring if the device supports FUA or not. Using this attribute
has an effect on the null_blk device only if memory backing is enabled
together with a write cache (cache_size option).

This new attribute allows configuring a null_blk device with a write
cache but without FUA support. This is convenient to test the block
layer flush machinery.

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>
Reviewed-by: default avatarChaitanya Kulkarni <kch@nvidia.com>
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/20240408014128.205141-18-dlemoal@kernel.org


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 997a1f08

drivers/block/null_blk/main.c

+10 −2
Original line number Diff line number Diff line
@@ -225,6 +225,10 @@ static unsigned long g_cache_size; 
module_param_named(cache_size, g_cache_size, ulong, 0444);

MODULE_PARM_DESC(mbps, "Cache size in MiB for memory-backed device. Default: 0 (none)");



static bool g_fua = true;

module_param_named(fua, g_fua, bool, 0444);

MODULE_PARM_DESC(zoned, "Enable/disable FUA support when cache_size is used. Default: true");



static unsigned int g_mbps;

module_param_named(mbps, g_mbps, uint, 0444);

MODULE_PARM_DESC(mbps, "Limit maximum bandwidth (in MiB/s). Default: 0 (no limit)");
@@ -446,6 +450,7 @@ NULLB_DEVICE_ATTR(virt_boundary, bool, NULL); 
NULLB_DEVICE_ATTR(no_sched, bool, NULL);

NULLB_DEVICE_ATTR(shared_tags, bool, NULL);

NULLB_DEVICE_ATTR(shared_tag_bitmap, bool, NULL);

NULLB_DEVICE_ATTR(fua, bool, NULL);



static ssize_t nullb_device_power_show(struct config_item *item, char *page)

{
@@ -593,6 +598,7 @@ static struct configfs_attribute *nullb_device_attrs[] = { 
	&nullb_device_attr_no_sched,

	&nullb_device_attr_shared_tags,

	&nullb_device_attr_shared_tag_bitmap,

	&nullb_device_attr_fua,

	NULL,

};
@@ -671,7 +677,7 @@ 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,

			"badblocks,blocking,blocksize,cache_size,"

			"badblocks,blocking,blocksize,cache_size,fua,"

			"completion_nsec,discard,home_node,hw_queue_depth,"

			"irqmode,max_sectors,mbps,memory_backed,no_sched,"

			"poll_queues,power,queue_mode,shared_tag_bitmap,"
@@ -763,6 +769,8 @@ static struct nullb_device *null_alloc_dev(void) 
	dev->no_sched = g_no_sched;

	dev->shared_tags = g_shared_tags;

	dev->shared_tag_bitmap = g_shared_tag_bitmap;

	dev->fua = g_fua;



	return dev;

}
@@ -1920,7 +1928,7 @@ static int null_add_dev(struct nullb_device *dev) 


	if (dev->cache_size > 0) {

		set_bit(NULLB_DEV_FL_CACHE, &nullb->dev->flags);

		blk_queue_write_cache(nullb->q, true, true);

		blk_queue_write_cache(nullb->q, true, dev->fua);

	}



	nullb->q->queuedata = nullb;

drivers/block/null_blk/null_blk.h

+1 −0
Original line number Diff line number Diff line
@@ -105,6 +105,7 @@ struct nullb_device { 
	bool no_sched; /* no IO scheduler for the device */

	bool shared_tags; /* share tag set between devices for blk-mq */

	bool shared_tag_bitmap; /* use hostwide shared tags */

	bool fua; /* Support FUA */

};



struct nullb {