From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anton Altaparmakov Subject: Re: Bug in error recovery in fs/buffer.c::__block_prepare_write() Date: Fri, 10 Jun 2005 14:05:15 +0100 Message-ID: <1118408715.31710.62.camel@imp.csi.cam.ac.uk> References: <1118408464.31710.54.camel@imp.csi.cam.ac.uk> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: fsdevel , lkml Return-path: Received: from ppsw-0.csi.cam.ac.uk ([131.111.8.130]:59827 "EHLO ppsw-0.csi.cam.ac.uk") by vger.kernel.org with ESMTP id S261536AbVFJNFY (ORCPT ); Fri, 10 Jun 2005 09:05:24 -0400 To: Al Viro , Linus Torvalds , Andrew Morton In-Reply-To: <1118408464.31710.54.camel@imp.csi.cam.ac.uk> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Here is the second patch (patch B). On Fri, 2005-06-10 at 14:01 +0100, Anton Altaparmakov wrote: [snip] > B) If we cannot safely allow buffer_new buffers to "leak out" of > __block_prepare_write(), then we simply would need to run a quick loop > over the buffers clearing buffer_new on each of them if it is set just > before returning "success" to the caller of __block_prepare_write(). [snip] The patch for this is simple, too (it is below). > Andrew/Linus, I would suggest that you apply at least A and perhaps B if > you deem it necessary or want to be on the safe side. > > Having had a look at the code it would seem perfectly safe to leave > buffer_new() set and ignore patch B but I may be wrong which is why I > did both. Signed-off-by: Anton Altaparmakov Best regards, Anton -- Anton Altaparmakov (replace at with @) Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK Linux NTFS maintainer / IRC: #ntfs on irc.freenode.net WWW: http://linux-ntfs.sf.net/ & http://www-stu.christs.cam.ac.uk/~aia21/ --- linux-2.6.git/fs/buffer.c.old2 2005-06-10 13:35:03.000000000 +0100 +++ linux-2.6.git/fs/buffer.c 2005-06-10 13:38:14.000000000 +0100 @@ -1992,9 +1992,14 @@ static int __block_prepare_write(struct if (!buffer_uptodate(*wait_bh)) err = -EIO; } - if (!err) + if (!err) { + bh = head; + do { + if (buffer_new(bh)) + clear_buffer_new(bh); + } while ((bh = bh->b_this_page) != head); return err; - + } /* Error case: */ /* * Zero out any newly allocated blocks to avoid exposing stale