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Date:   Wed, 8 Mar 2023 15:28:18 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Qu Wenruo <quwenruo.btrfs@gmx.com>
Cc:     Christoph Hellwig <hch@lst.de>, Chris Mason <clm@fb.com>,
        Josef Bacik <josef@toxicpanda.com>,
        David Sterba <dsterba@suse.com>,
        Damien Le Moal <damien.lemoal@wdc.com>,
        Naohiro Aota <naohiro.aota@wdc.com>,
        Johannes Thumshirn <johannes.thumshirn@wdc.com>,
        Qu Wenruo <wqu@suse.com>, Jens Axboe <axboe@kernel.dk>,
        "Darrick J. Wong" <djwong@kernel.org>, linux-block@vger.kernel.org,
        linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 03/34] btrfs: add a btrfs_inode pointer to struct
 btrfs_bio
Message-ID: <20230308142817.GA14929@lst.de>
References: <20230121065031.1139353-1-hch@lst.de> <20230121065031.1139353-4-hch@lst.de> <88b2fae1-8d95-2172-7bc4-c5dfc4ff7410@gmx.com> <20230307144106.GA19477@lst.de> <96f5c29c-1b25-66af-1ba1-731ae39d912d@gmx.com> <5aff53ea-0666-d4d6-3bf1-07b3674a405a@gmx.com>
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On Wed, Mar 08, 2023 at 02:04:26PM +0800, Qu Wenruo wrote:
> BTW, I also checked if I can craft a scrub specific version of 
> btrfs_submit_bio().
>
> The result doesn't look good at all.
>
> Without a btrfs_bio structure, it's already pretty hard to properly put 
> bioc, decrease the bio counter.
>
> Or I need to create a scrub_bio, and re-implement all the needed endio 
> function handling.
>
> So please really consider the simplest case, one just wants to read/write 
> some data using logical + mirror_num, without any btrfs inode nor csum 
> verification.

As said before with a little more work we could get away without the
inode.  But the above sounds a little strange to me.  Can you share
your current code?  Maybe I can come up with some better ideas.