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Date:   Mon, 12 Sep 2022 15:58:35 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Josef Bacik <josef@toxicpanda.com>
Cc:     Christoph Hellwig <hch@lst.de>, Chris Mason <clm@fb.com>,
        David Sterba <dsterba@suse.com>,
        Damien Le Moal <damien.lemoal@wdc.com>,
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        linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        osandov@osandov.com
Subject: Re: [PATCH 07/17] btrfs: allow btrfs_submit_bio to split bios
Message-ID: <20220912135835.GC723@lst.de>
References: <20220901074216.1849941-1-hch@lst.de> <20220901074216.1849941-8-hch@lst.de> <YxkFUeLBWhnufb7U@localhost.localdomain>
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On Wed, Sep 07, 2022 at 04:55:45PM -0400, Josef Bacik wrote:
> I'm worried about this for the ONE_ORDERED case.  We specifically used the
> ONE_ORDERED thing because our file_offset was the start, but our length could go
> past the range of the ordered extent, and then we wouldn't find our ordered
> extent and things would go quite wrong.
> 
> Instead we should do something like
> 
> if (!(orig->bi_opf & REQ_BTRFS_ONE_ORDERED))
> 	orig_bbio->file_offset += map_length;
> 
> I've cc'ed Omar since he's the one who added this and I'm a little confused
> about how this can happen.

I have to say I found the logic quite confusing as well, and when I
broke it during development of this series xfstests did not complain
either.  So shedding some more light on the flag would be really
helpful.