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-rw-r--r--block/blk-merge.c19
-rw-r--r--include/linux/bio.h7
2 files changed, 24 insertions, 2 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 5efc9e7a68b7..857dce7634b6 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -95,6 +95,9 @@ new_hw_segment:
nr_hw_segs++;
}
+ if (nr_phys_segs == 1 && seg_size > rq->bio->bi_seg_front_size)
+ rq->bio->bi_seg_front_size = seg_size;
+
nr_phys_segs++;
bvprv = bv;
seg_size = bv->bv_len;
@@ -106,6 +109,10 @@ new_hw_segment:
rq->bio->bi_hw_front_size = hw_seg_size;
if (hw_seg_size > rq->biotail->bi_hw_back_size)
rq->biotail->bi_hw_back_size = hw_seg_size;
+ if (nr_phys_segs == 1 && seg_size > rq->bio->bi_seg_front_size)
+ rq->bio->bi_seg_front_size = seg_size;
+ if (seg_size > rq->biotail->bi_seg_back_size)
+ rq->biotail->bi_seg_back_size = seg_size;
rq->nr_phys_segments = nr_phys_segs;
rq->nr_hw_segments = nr_hw_segs;
}
@@ -133,7 +140,8 @@ static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
if (!BIOVEC_PHYS_MERGEABLE(__BVEC_END(bio), __BVEC_START(nxt)))
return 0;
- if (bio->bi_size + nxt->bi_size > q->max_segment_size)
+ if (bio->bi_seg_back_size + nxt->bi_seg_front_size >
+ q->max_segment_size)
return 0;
/*
@@ -377,6 +385,8 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
{
int total_phys_segments;
int total_hw_segments;
+ unsigned int seg_size =
+ req->biotail->bi_seg_back_size + next->bio->bi_seg_front_size;
/*
* First check if the either of the requests are re-queued
@@ -392,8 +402,13 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
return 0;
total_phys_segments = req->nr_phys_segments + next->nr_phys_segments;
- if (blk_phys_contig_segment(q, req->biotail, next->bio))
+ if (blk_phys_contig_segment(q, req->biotail, next->bio)) {
+ if (req->nr_phys_segments == 1)
+ req->bio->bi_seg_front_size = seg_size;
+ if (next->nr_phys_segments == 1)
+ next->biotail->bi_seg_back_size = seg_size;
total_phys_segments--;
+ }
if (total_phys_segments > q->max_phys_segments)
return 0;
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 0933a14e6414..3d8394732d94 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -98,6 +98,13 @@ struct bio {
unsigned int bi_size; /* residual I/O count */
/*
+ * To keep track of the max segment size, we account for the
+ * sizes of the first and last mergeable segments in this bio.
+ */
+ unsigned int bi_seg_front_size;
+ unsigned int bi_seg_back_size;
+
+ /*
* To keep track of the max hw size, we account for the
* sizes of the first and last virtually mergeable segments
* in this bio