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From: Christoph Hellwig <hch@infradead.org>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	Brian Foster <bfoster@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] iomap: Ensure iop->uptodate matches PageUptodate
Date: Sun, 26 Jul 2020 16:15:04 +0100	[thread overview]
Message-ID: <20200726151504.GA24553@infradead.org> (raw)
In-Reply-To: <20200726091052.30576-1-willy@infradead.org>

On Sun, Jul 26, 2020 at 10:10:52AM +0100, Matthew Wilcox (Oracle) wrote:
> If the filesystem has block size < page size and we end up calling
> iomap_page_create() in iomap_page_mkwrite_actor(), the uptodate bits
> would be zero, which causes us to skip writeback of blocks which are
> !uptodate in iomap_writepage_map().  This can lead to user data loss.
> 
> Found using generic/127 with the THP patches.  I don't think this can be
> reproduced on mainline using that test (the THP code causes iomap_pages
> to be discarded more frequently), but inspection shows it can happen
> with an appropriate series of operations.

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>

  reply	other threads:[~2020-07-26 15:15 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-26  9:10 Matthew Wilcox (Oracle)
2020-07-26 15:15 ` Christoph Hellwig [this message]
2020-07-26 23:06 ` Dave Chinner
2020-07-26 23:20   ` Matthew Wilcox
2020-07-26 23:53     ` Dave Chinner
2020-07-28  9:23       ` Christoph Hellwig
2020-07-28 13:15         ` Matthew Wilcox

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