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-rw-r--r--block/ll_rw_blk.c24
-rw-r--r--include/linux/blkdev.h1
2 files changed, 25 insertions, 0 deletions
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 8b919940b2a..14af36c5cdb 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -760,6 +760,30 @@ void blk_queue_dma_alignment(struct request_queue *q, int mask)
EXPORT_SYMBOL(blk_queue_dma_alignment);
/**
+ * blk_queue_update_dma_alignment - update dma length and memory alignment
+ * @q: the request queue for the device
+ * @mask: alignment mask
+ *
+ * description:
+ * update required memory and length aligment for direct dma transactions.
+ * If the requested alignment is larger than the current alignment, then
+ * the current queue alignment is updated to the new value, otherwise it
+ * is left alone. The design of this is to allow multiple objects
+ * (driver, device, transport etc) to set their respective
+ * alignments without having them interfere.
+ *
+ **/
+void blk_queue_update_dma_alignment(struct request_queue *q, int mask)
+{
+ BUG_ON(mask > PAGE_SIZE);
+
+ if (mask > q->dma_alignment)
+ q->dma_alignment = mask;
+}
+
+EXPORT_SYMBOL(blk_queue_update_dma_alignment);
+
+/**
* blk_queue_find_tag - find a request by its tag and queue
* @q: The request queue for the device
* @tag: The tag of the request
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index d18ee67b40f..81e99e51630 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -766,6 +766,7 @@ extern void blk_queue_segment_boundary(struct request_queue *, unsigned long);
extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn);
extern void blk_queue_merge_bvec(struct request_queue *, merge_bvec_fn *);
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_softirq_done(struct request_queue *, softirq_done_fn *);
extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev);
extern int blk_queue_ordered(struct request_queue *, unsigned, prepare_flush_fn *);