On 2016-02-21, at 3:28 PM, James Bottomley wrote:
> That said, I still can't reproduce this, so you're going to have to
> help me find it. Current theory is ll_merge_request_fn() it looks like
> there's scope for miscalculation in there. Can you instrument this
> line
>
> /* Merge is OK... */
> req->nr_phys_segments = total_phys_segments;
>
> To add just before the return
>
> if (req->nr_phys_segments != __blk_recalc_rq_segments(rq->q, rq->bio, false)
> printk("MISMATCH IN MERGE: got %d, should get %d\n",
> req->nr_phys_segments,
> __blk_recalc_rq_segments(rq->q, rq->bio, false));
This didn't trigger. There were some typos:
diff --git a/block/blk-merge.c b/block/blk-merge.c
index d9c3a75..e8969ef 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -545,6 +545,12 @@ static int ll_merge_requests_fn(struct request_queue *q, struct request *req,
/* Merge is OK... */
req->nr_phys_segments = total_phys_segments;
+
+if (req->nr_phys_segments != __blk_recalc_rq_segments(req->q, req->bio, false))
+ printk("MISMATCH IN MERGE: got %d, should get %d\n",
+ req->nr_phys_segments,
+ __blk_recalc_rq_segments(req->q, req->bio, false));
+
return 1;
}
Any more ideas?
Dave
--
John David Anglin dave.anglin@xxxxxxxx
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