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Commit 45147fb5 authored by Yoshihiro Shimoda's avatar Yoshihiro Shimoda Committed by Christoph Hellwig
Browse files

block: add a helper function to merge the segments 



This patch adds a helper function whether a queue can merge
the segments by the DMA MAP layer (e.g. via IOMMU).

Signed-off-by: default avatarYoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarSimon Horman <horms+renesas@verge.net.au>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent db91427b

block/blk-settings.c

+23 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <linux/lcm.h>

#include <linux/jiffies.h>

#include <linux/gfp.h>

#include <linux/dma-mapping.h>



#include "blk.h"

#include "blk-wbt.h"
@@ -832,6 +833,28 @@ void blk_queue_write_cache(struct request_queue *q, bool wc, bool fua) 
}

EXPORT_SYMBOL_GPL(blk_queue_write_cache);



/**

 * blk_queue_can_use_dma_map_merging - configure queue for merging segments.

 * @q:		the request queue for the device

 * @dev:	the device pointer for dma

 *

 * Tell the block layer about merging the segments by dma map of @q.

 */

bool blk_queue_can_use_dma_map_merging(struct request_queue *q,

				       struct device *dev)

{

	unsigned long boundary = dma_get_merge_boundary(dev);



	if (!boundary)

		return false;



	/* No need to update max_segment_size. see blk_queue_virt_boundary() */

	blk_queue_virt_boundary(q, boundary);



	return true;

}

EXPORT_SYMBOL_GPL(blk_queue_can_use_dma_map_merging);



static int __init blk_settings_init(void)

{

	blk_max_low_pfn = max_low_pfn - 1;

include/linux/blkdev.h

+2 −0
Original line number Diff line number Diff line
@@ -1085,6 +1085,8 @@ extern void blk_queue_dma_alignment(struct request_queue *, int); 
extern void blk_queue_update_dma_alignment(struct request_queue *, int);

extern void blk_queue_rq_timeout(struct request_queue *, unsigned int);

extern void blk_queue_write_cache(struct request_queue *q, bool enabled, bool fua);

extern bool blk_queue_can_use_dma_map_merging(struct request_queue *q,

					      struct device *dev);



/*

 * Number of physical segments as sent to the device.