Convert the main rq mapper (blk_rq_map_sg()) to the sg helper setup.

Signed-off-by: Jens Axboe <[EMAIL PROTECTED]>
---
 block/ll_rw_blk.c |   19 ++++++++++++-------
 1 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 17e1889..b01a5f2 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -30,6 +30,7 @@
 #include <linux/cpu.h>
 #include <linux/blktrace_api.h>
 #include <linux/fault-inject.h>
+#include <linux/scatterlist.h>
 
 /*
  * for max sense size
@@ -1307,9 +1308,11 @@ static int blk_hw_contig_segment(request_queue_t *q, 
struct bio *bio,
  * map a request to scatterlist, return number of sg entries setup. Caller
  * must make sure sg can hold rq->nr_phys_segments entries
  */
-int blk_rq_map_sg(request_queue_t *q, struct request *rq, struct scatterlist 
*sg)
+int blk_rq_map_sg(request_queue_t *q, struct request *rq,
+                 struct scatterlist *sglist)
 {
        struct bio_vec *bvec, *bvprv;
+       struct scatterlist *next_sg, *sg;
        struct bio *bio;
        int nsegs, i, cluster;
 
@@ -1320,6 +1323,7 @@ int blk_rq_map_sg(request_queue_t *q, struct request *rq, 
struct scatterlist *sg
         * for each bio in rq
         */
        bvprv = NULL;
+       sg = next_sg = &sglist[0];
        rq_for_each_bio(bio, rq) {
                /*
                 * for each segment in bio
@@ -1328,7 +1332,7 @@ int blk_rq_map_sg(request_queue_t *q, struct request *rq, 
struct scatterlist *sg
                        int nbytes = bvec->bv_len;
 
                        if (bvprv && cluster) {
-                               if (sg[nsegs - 1].length + nbytes > 
q->max_segment_size)
+                               if (sg->length + nbytes > q->max_segment_size)
                                        goto new_segment;
 
                                if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec))
@@ -1336,14 +1340,15 @@ int blk_rq_map_sg(request_queue_t *q, struct request 
*rq, struct scatterlist *sg
                                if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec))
                                        goto new_segment;
 
-                               sg[nsegs - 1].length += nbytes;
+                               sg->length += nbytes;
                        } else {
 new_segment:
-                               memset(&sg[nsegs],0,sizeof(struct scatterlist));
-                               sg[nsegs].page = bvec->bv_page;
-                               sg[nsegs].length = nbytes;
-                               sg[nsegs].offset = bvec->bv_offset;
+                               sg = next_sg;
+                               next_sg = sg_next(sg);
 
+                               sg->page = bvec->bv_page;
+                               sg->length = nbytes;
+                               sg->offset = bvec->bv_offset;
                                nsegs++;
                        }
                        bvprv = bvec;
-- 
1.5.2.rc1

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