linux-kernel - Re: [PATCH 1/2] block: export __blk_complete

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Date:   Fri, 15 Jun 2018 10:22:46 +0800
From:   "jianchao.wang" <jianchao.w.wang@...cle.com>
To:     Ming Lei <tom.leiming@...il.com>
Cc:     Jens Axboe <axboe@...nel.dk>, Christoph Hellwig <hch@....de>,
        James Bottomley <jejb@...ux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        linux-block <linux-block@...r.kernel.org>,
        Linux SCSI List <linux-scsi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] block: export __blk_complete_request

Hi Ming

On 06/15/2018 10:17 AM, Ming Lei wrote:
> On Fri, Jun 15, 2018 at 9:57 AM, Jianchao Wang
> <jianchao.w.wang@...cle.com> wrote:
>> After f6e7d48 (block: remove BLK_EH_HANDLED), LLDD is responsible
>> to complete the timed out request, however, for blk-legacy, the
>> 'complete' is still marked, blk_complete_request will do nothing,
>> we export __blk_complete_request for LLDD to complete the request
>> in timeout path.
>>
>> Signed-off-by: Jianchao Wang <jianchao.w.wang@...cle.com>
>> ---
>>  block/blk-softirq.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/block/blk-softirq.c b/block/blk-softirq.c
>> index 01e2b35..15c1f5e 100644
>> --- a/block/blk-softirq.c
>> +++ b/block/blk-softirq.c
>> @@ -144,6 +144,7 @@ void __blk_complete_request(struct request *req)
>>
>>         local_irq_restore(flags);
>>  }
>> +EXPORT_SYMBOL(__blk_complete_request);
>>
>>  /**
>>   * blk_complete_request - end I/O on a request
>> --
>> 2.7.4
>>
> 
> Looks non-blk-mq timeout code need to convert to ref-counter
> based approach too?

IMO, ref-counter is just to fix the blk-mq req life recycle issue.
It cannot replace the blk_mark_rq_complete which could avoid the race between
timeout and io completion path.
Or maybe my understanding is wrong ...

Thanks
Jianchao
>