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Message-ID: <20140221002107.GB7232@thunk.org> Date: Thu, 20 Feb 2014 19:21:07 -0500 From: Theodore Ts'o <tytso@....edu> To: Jan Kara <jack@...e.cz> Cc: Maxim Patlasov <MPatlasov@...allels.com>, adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH] ext4: avoid exposure of stale data in ext4_punch_hole() -v2 On Fri, Sep 27, 2013 at 06:05:17PM +0200, Jan Kara wrote: > On Fri 27-09-13 19:54:03, Maxim Patlasov wrote: > > While handling punch-hole fallocate, it's useless to truncate page cache > > before removing the range from extent tree (or block map in indirect case) > > because page cache can be re-populated (by read-ahead or read(2) or mmap-ed > > read) immediately after truncating page cache, but before updating extent > > tree (or block map). In that case the user will see stale data even after > > fallocate is completed. > > > > Changed in v2 (Thanks to Jan Kara): > > - Until the problem of data corruption resulting from pages backed by > > already freed blocks is fully resolved, the simple thing we can do now > > is to add another truncation of pagecache after punch hole is done. > The patch looks good. You can add: > Reviewed-by: Jan Kara <jack@...e.cz> I was going through old patches, and it looks like this one got dropped. My apologies. As far as I can tell, the underlying problem in the VFS/MM layer hasn't been solved yet (Jan, can you confirm?), so I've queued this patch for the next merge window. - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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