block: add blk_rq_aligned helper function
This adds blk_rq_aligned helper function to see if alignment and
padding requirement is satisfied for DMA transfer. This also converts
blk_rq_map_kern and __blk_rq_map_user to use the helper function.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 358ac42..9c25492 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -899,6 +899,13 @@
return q ? q->dma_alignment : 511;
}
+static inline int blk_rq_aligned(struct request_queue *q, void *addr,
+ unsigned int len)
+{
+ unsigned int alignment = queue_dma_alignment(q) | q->dma_pad_mask;
+ return !((unsigned long)addr & alignment) && !(len & alignment);
+}
+
/* assumes size > 256 */
static inline unsigned int blksize_bits(unsigned int size)
{