From ba951841ceb7fa5b06ad48caa5270cc2ae17941e Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 17 Oct 2007 19:34:11 +0200 Subject: [PATCH] [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 --- block/ll_rw_blk.c | 10 ++++++---- 1 file 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;