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).

Yoshihiro Shimoda committed 7 years ago

Commit 45147fb1 parent db914272 files · +25 −0Browse files

Unified · Split

2 files

@@ -12,6 +12,7 @@ · 11 unmodified lines
12	12	#include <linux/lcm.h>
13	13	#include <linux/jiffies.h>
14	14	#include <linux/gfp.h>
	15	+#include <linux/dma-mapping.h>
15	16
16	17	#include "blk.h"
17	18	#include "blk-wbt.h"
@@ -832,6 +833,28 @@ void blk_queue_write_cache(struct request_queue *q, bool wc, bool fua) · 814 unmodified lines
832	833	}
833	834	EXPORT_SYMBOL_GPL(blk_queue_write_cache);
834	835
	836	+/**
	837	+ * blk_queue_can_use_dma_map_merging - configure queue for merging segments.
	838	+ * @q: the request queue for the device
	839	+ * @dev: the device pointer for dma
	840	+ *
	841	+ * Tell the block layer about merging the segments by dma map of @q.
	842	+ */
	843	+bool blk_queue_can_use_dma_map_merging(struct request_queue *q,
	844	+ struct device *dev)
	845	+{
	846	+ unsigned long boundary = dma_get_merge_boundary(dev);
	847	+
	848	+ if (!boundary)
	849	+ return false;
	850	+
	851	+ /* No need to update max_segment_size. see blk_queue_virt_boundary() */
	852	+ blk_queue_virt_boundary(q, boundary);
	853	+
	854	+ return true;
	855	+}
	856	+EXPORT_SYMBOL_GPL(blk_queue_can_use_dma_map_merging);
	857	+
835	858	static int __init blk_settings_init(void)
836	859	{
837	860	blk_max_low_pfn = max_low_pfn - 1;

@@ -1085,6 +1085,8 @@ extern void blk_queue_dma_alignment(struct request_queue *, int); · 1084 unmodified lines
1085	1085	extern void blk_queue_update_dma_alignment(struct request_queue *, int);
1086	1086	extern void blk_queue_rq_timeout(struct request_queue *, unsigned int);
1087	1087	extern void blk_queue_write_cache(struct request_queue *q, bool enabled, bool fua);
	1088	+extern bool blk_queue_can_use_dma_map_merging(struct request_queue *q,
	1089	+ struct device *dev);
1088	1090
1089	1091	/*
1090	1092	* Number of physical segments as sent to the device.