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authorJens Axboe <jens.axboe@oracle.com>2007-10-17 19:34:11 +0200
committerJens Axboe <jens.axboe@oracle.com>2007-10-17 19:34:11 +0200
commitba951841ceb7fa5b06ad48caa5270cc2ae17941e (patch)
treefda194f4506fb2af93895d3aac1902051678e8e0 /block
parenta3bec5c5aea0da263111c4d8f8eabc1f8560d7bf (diff)
downloadlinux-ba951841ceb7fa5b06ad48caa5270cc2ae17941e.tar.gz
[BLOCK] blk_rq_map_sg() next_sg fixup
Don't ever use sg_next() on the last entry, it may not be valid!

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block')
-rw-r--r--block/ll_rw_blk.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 9e3f3cc85d0d..3935469e3662 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -1322,8 +1322,8 @@ int blk_rq_map_sg(struct request_queue *q, struct request *rq,
 		  struct scatterlist *sglist)
 {
 	struct bio_vec *bvec, *bvprv;
-	struct scatterlist *next_sg, *sg;
 	struct req_iterator iter;
+	struct scatterlist *sg;
 	int nsegs, cluster;
 
 	nsegs = 0;
@@ -1333,7 +1333,7 @@ int blk_rq_map_sg(struct request_queue *q, struct request *rq,
 	 * for each bio in rq
 	 */
 	bvprv = NULL;
-	sg = next_sg = &sglist[0];
+	sg = NULL;
 	rq_for_each_segment(bvec, rq, iter) {
 		int nbytes = bvec->bv_len;
 
@@ -1349,8 +1349,10 @@ int blk_rq_map_sg(struct request_queue *q, struct request *rq,
 			sg->length += nbytes;
 		} else {
 new_segment:
-			sg = next_sg;
-			next_sg = sg_next(sg);
+			if (!sg)
+				sg = sglist;
+			else
+				sg = sg_next(sg);
 
 			memset(sg, 0, sizeof(*sg));
 			sg->page = bvec->bv_page;