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Date:   Fri, 26 May 2023 08:41:23 +0200
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>, linux-btrfs@vger.kernel.org,
        Johannes Thumshirn <johannes.thumshirn@wdc.com>,
        Qu Wenruo <wqu@suse.com>
Subject: Re: [PATCH 15/21] btrfs: remove the extent_buffer lookup in btree
 block checksumming
Message-ID: <20230526064123.GA10378@lst.de>
References: <20230503152441.1141019-1-hch@lst.de> <20230503152441.1141019-16-hch@lst.de> <1442e52f-9ba1-d9fa-f439-34d31b46800f@gmx.com>
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On Fri, May 26, 2023 at 02:39:54PM +0800, Qu Wenruo wrote:
>> +	if (WARN_ON_ONCE(found_start != eb->start))
>> +		return BLK_STS_IOERR;
>> +	if (WARN_ON_ONCE(!PageUptodate(eb->pages[0])))
>> +		return BLK_STS_IOERR;
>
> Unfortunately this is screwing up subpage support.
>
> Previously subpage goes its own helper, which replaces the uptodate
> check to using the subpage helper.
>
> Since PageUptodate flag is only set when all eb in that page is uptodate.
> If we have a hole in the page range, the page will never be marked Uptodate.
>
> Thus for any subpage mount, this would lead to transaction abort during
> metadata writeback.
>
> We have btrfs_page_clamp_test_uptodate() for this usage.

True, this should use the sub page helper.  Or maybe just drop
this assert altogether?