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Date: Fri, 20 May 2011 16:31:56 +0800
Message-ID: <BANLkTik5Od9tLg1F6mDFkzpViXR2ZcRmgA@mail.gmail.com>
Subject: Re: [PATCH] block: call elv_bio_merged() when merged
From: Shaohua Li <shaohua.li@intel.com>
To: Namhyung Kim <namhyung@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>, linux-kernel@vger.kernel.org,
        Divyesh Shah <dpshah@google.com>
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2011/5/20 Namhyung Kim <namhyung@gmail.com>:
> Commit 73c101011926 ("block: initial patch for on-stack per-task plugging")
> removed calls to elv_bio_merged() when @bio merged with @req. Re-add them.
>
> Signed-off-by: Namhyung Kim <namhyung@gmail.com>
> Cc: Divyesh Shah <dpshah@google.com>
> ---
> ?block/blk-core.c | ? ?2 ++
> ?1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 3fe00a14822a..4dc02ef5fc82 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -1132,6 +1132,7 @@ static bool bio_attempt_back_merge(struct request_queue *q, struct request *req,
> ? ? ? ?req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
>
> ? ? ? ?drive_stat_acct(req, 0);
> + ? ? ? elv_bio_merged(q, req, bio);
> ? ? ? ?return true;
> ?}
>
> @@ -1173,6 +1174,7 @@ static bool bio_attempt_front_merge(struct request_queue *q,
> ? ? ? ?req->ioprio = ioprio_best(req->ioprio, bio_prio(bio));
>
> ? ? ? ?drive_stat_acct(req, 0);
> + ? ? ? elv_bio_merged(q, req, bio);
> ? ? ? ?return true;
> ?}
Looks you should do this in __make_request. when the routine is called
in attempt_plug_merge, the request isn't added to elevator yet.

Thanks,
Shaohua
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