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-rw-r--r--block/blk-merge.c35
1 files changed, 30 insertions, 5 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c
index de5716d8..e01405a 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -76,6 +76,9 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
struct bio_vec bv, bvprv, *bvprvp = NULL;
struct bvec_iter iter;
unsigned seg_size = 0, nsegs = 0, sectors = 0;
+ unsigned front_seg_size = bio->bi_seg_front_size;
+ bool do_split = true;
+ struct bio *new = NULL;
bio_for_each_segment(bv, bio, iter) {
if (sectors + (bv.bv_len >> 9) > queue_max_sectors(q))
@@ -98,8 +101,11 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
seg_size += bv.bv_len;
bvprv = bv;
- bvprvp = &bv;
+ bvprvp = &bvprv;
sectors += bv.bv_len >> 9;
+
+ if (nsegs == 1 && seg_size > front_seg_size)
+ front_seg_size = seg_size;
continue;
}
new_segment:
@@ -108,16 +114,29 @@ new_segment:
nsegs++;
bvprv = bv;
- bvprvp = &bv;
+ bvprvp = &bvprv;
seg_size = bv.bv_len;
sectors += bv.bv_len >> 9;
+
+ if (nsegs == 1 && seg_size > front_seg_size)
+ front_seg_size = seg_size;
}
- *segs = nsegs;
- return NULL;
+ do_split = false;
split:
*segs = nsegs;
- return bio_split(bio, sectors, GFP_NOIO, bs);
+
+ if (do_split) {
+ new = bio_split(bio, sectors, GFP_NOIO, bs);
+ if (new)
+ bio = new;
+ }
+
+ bio->bi_seg_front_size = front_seg_size;
+ if (seg_size > bio->bi_seg_back_size)
+ bio->bi_seg_back_size = seg_size;
+
+ return do_split ? new : NULL;
}
void blk_queue_split(struct request_queue *q, struct bio **bio,
@@ -412,6 +431,12 @@ int blk_rq_map_sg(struct request_queue *q, struct request *rq,
if (sg)
sg_mark_end(sg);
+ /*
+ * Something must have been wrong if the figured number of
+ * segment is bigger than number of req's physical segments
+ */
+ WARN_ON(nsegs > rq->nr_phys_segments);
+
return nsegs;
}
EXPORT_SYMBOL(blk_rq_map_sg);
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