Commit 3850e13f authored by Keith Busch's avatar Keith Busch Committed by Jens Axboe
Browse files

block: export dma_alignment attribute 



User space may want to know how to align their buffers to avoid
bouncing. Export the queue attribute.

Signed-off-by: default avatarKeith Busch <kbusch@kernel.org>
Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220610195830.3574005-4-kbusch@fb.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent c58c0074

Documentation/ABI/stable/sysfs-block

+9 −0
Original line number Diff line number Diff line
@@ -260,6 +260,15 @@ Description: 
		for discards, and don't read this file.





What:		/sys/block/<disk>/queue/dma_alignment

Date:		May 2022

Contact:	linux-block@vger.kernel.org

Description:

		Reports the alignment that user space addresses must have to be

		used for raw block device access with O_DIRECT and other driver

		specific passthrough mechanisms.





What:		/sys/block/<disk>/queue/fua

Date:		May 2018

Contact:	linux-block@vger.kernel.org

block/blk-sysfs.c

+7 −0
Original line number Diff line number Diff line
@@ -274,6 +274,11 @@ static ssize_t queue_virt_boundary_mask_show(struct request_queue *q, char *page 
	return queue_var_show(q->limits.virt_boundary_mask, page);

}



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

{

	return queue_var_show(queue_dma_alignment(q), page);

}



#define QUEUE_SYSFS_BIT_FNS(name, flag, neg)				\

static ssize_t								\

queue_##name##_show(struct request_queue *q, char *page)		\
@@ -606,6 +611,7 @@ QUEUE_RO_ENTRY(queue_dax, "dax"); 
QUEUE_RW_ENTRY(queue_io_timeout, "io_timeout");

QUEUE_RW_ENTRY(queue_wb_lat, "wbt_lat_usec");

QUEUE_RO_ENTRY(queue_virt_boundary_mask, "virt_boundary_mask");

QUEUE_RO_ENTRY(queue_dma_alignment, "dma_alignment");



#ifdef CONFIG_BLK_DEV_THROTTLING_LOW

QUEUE_RW_ENTRY(blk_throtl_sample_time, "throttle_sample_time");
@@ -667,6 +673,7 @@ static struct attribute *queue_attrs[] = { 
	&blk_throtl_sample_time_entry.attr,

#endif

	&queue_virt_boundary_mask_entry.attr,

	&queue_dma_alignment_entry.attr,

	NULL,

};