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Date:   Thu, 10 Aug 2023 17:58:35 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Chengming Zhou <zhouchengming@bytedance.com>
Cc:     Christoph Hellwig <hch@lst.de>,
        Chuck Lever III <chuck.lever@oracle.com>,
        Jens Axboe <axboe@kernel.dk>, Chuck Lever <cel@kernel.org>,
        "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
        Damien Le Moal <dlemoal@kernel.org>
Subject: Re: [PATCH RFC] block: Revert 615939a2ae73
Message-ID: <20230810155835.GF28000@lst.de>
References: <169158653156.2034.8363987273532378512.stgit@bazille.1015granger.net> <d51b0683-8872-4e10-8589-5c6de8db61d4@kernel.dk> <20230809161105.GA2304@lst.de> <9BADCC53-72E9-44FB-80C8-CEBC9897809D@oracle.com> <20230809214913.GA9902@lst.de> <86ce2299-ce42-c0bb-e577-9d23f8af494c@bytedance.com>
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On Thu, Aug 10, 2023 at 11:42:50AM +0800, Chengming Zhou wrote:
> Christoph, it would be very helpful if you share some thoughts
> and directions.

I am not quite sure where the problems could even be.  I think the
interesting aspects are:

 - we are not directly processing through the normal submission path
   instead of adding the command to the flush_data_in_flight list and
   then going through blk_kick_flush.  So a command now gets executed
   earlier than it did before.

 - given that it only happens with SATA, it must be in some way related
   to the fact that ATA flush commands are not queud, that is when a
   flush is outstanding no other command can't.