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[BLOCK] blk_rq_map_sg() next_sg fixup

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Don't ever use sg_next() on the last entry, it may not be valid!

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jens Axboe 2007-10-17 19:34:11 +02:00
parent a3bec5c5ae
commit ba951841ce
1 changed files with 6 additions and 4 deletions
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10
block/ll_rw_blk.c
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@ -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;