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Date:   Tue, 26 May 2020 11:44:28 -0500
From:   Goldwyn Rodrigues <rgoldwyn@suse.de>
To:     Johannes Thumshirn <Johannes.Thumshirn@wdc.com>
Cc:     "linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>,
        "hch@infradead.org" <hch@infradead.org>,
        "dsterba@suse.cz" <dsterba@suse.cz>
Subject: Re: [PATCH 4/7] btrfs: Switch to iomap_dio_rw() for dio
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On 15:03 26/05, Johannes Thumshirn wrote:
> Just as a heads up, this one gives me lot's of Page cache invalidation
> failure prints from dio_warn_stale_pagecache() on btrfs/004 with 
> current misc-next:
> 
<snip>

> [   23.696400] Page cache invalidation failure on direct I/O.  Possible data corruption due to collision with buffered I/O!
> [   23.698115] File: /mnt/scratch/bgnoise/p0/f0 PID: 6562 Comm: fsstress
> 
> I have no idea yet why but I'm investigating.

This is caused because we are trying to release a page when the extent
has locked the page and release page returns false. To minimize the
effect, I had proposed a patch [1] in v6. However, this created
more extent locking issues and so was dropped.

[1] https://patchwork.kernel.org/patch/11275063/

-- 
Goldwyn