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Message-ID: <259badcd-fa15-8194-9e2c-d8fc2e1593bd@linux.dev>
Date: Mon, 31 Jul 2023 22:15:46 +0800
From: Chengming Zhou <chengming.zhou@...ux.dev>
To: Christoph Hellwig <hch@....de>
Cc: axboe@...nel.dk, ming.lei@...hat.com, linux-block@...r.kernel.org,
linux-kernel@...r.kernel.org, zhouchengming@...edance.com
Subject: Re: [PATCH v2 2/4] blk-flush: split queues for preflush and postflush
requests
On 2023/7/31 14:15, Christoph Hellwig wrote:
>> - list_for_each_entry_safe(rq, n, running, queuelist) {
>> + list_for_each_entry_safe(rq, n, preflush_running, queuelist) {
>> + unsigned int seq = blk_flush_cur_seq(rq);
>> +
>> + BUG_ON(seq != REQ_FSEQ_PREFLUSH && seq != REQ_FSEQ_POSTFLUSH);
>> + blk_flush_complete_seq(rq, fq, seq, error);
>> + }
>> +
>> + list_for_each_entry_safe(rq, n, postflush_running, queuelist) {
>> unsigned int seq = blk_flush_cur_seq(rq);
>>
>> BUG_ON(seq != REQ_FSEQ_PREFLUSH && seq != REQ_FSEQ_POSTFLUSH);
>
> Shouldn't the BUG_ON be split into one that only checks for PREFLUSH and
> one only for POSTFLUSH?
Ah yes, will fix it.
>
>> + if (fq->flush_pending_idx != fq->flush_running_idx)
>> + return;
>> +
>> + if (!list_empty(preflush_pending))
>> + first_rq = list_first_entry(preflush_pending, struct request, queuelist);
>> + else if (!list_empty(postflush_pending))
>> + first_rq = list_first_entry(postflush_pending, struct request, queuelist);
>> + else
>> return;
>
> Hmm, I don't think both lists can be empty here?
Yes if check fq->flush_pending_since != 0 before.
>
> I'd simplify this and avoid the overly long lines as:
>
> first_rq = list_first_entry_or_null(preflush_pending, struct request,
> queuelist);
> if (!first_rq)
> first_rq = list_first_entry_or_null(postflush_pending,
> struct request, queuelist);
>
This is better, will change it.
Thanks.
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