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From: Chris Mason <mason@suse.com>
To: Olaf Hering <olh@suse.de>
Subject: Re: [PATCH] cramfs corruption after BLKFLSBUF on loop device
Date: Thu, 1 Jun 2006 16:29:19 -0400
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Cc: Andrew Morton <akpm@osdl.org>, linux-kernel@vger.kernel.org,
       Al Viro <viro@ftp.linux.org.uk>
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On Thursday 01 June 2006 16:20, Olaf Hering wrote:
>  On Thu, Jun 01, Chris Mason wrote:
> > I think this will work (but have not tested it).  Another option is to
> > create a read_cache_page that pins the page via a page flag
> > that invalidate_mapping_pages will honor.
>
> PageLocked or PageDirty, the latter only with a mb().

The problem is we need the bit to be set before we set the page up to date.  A 
locked page will never make it through the readpage() mechanisms and a dirty 
page that isn't up to date is not quite legal.

For cramfs, dirty would work I suppose.

-chris