To: mrmacman_g4@mac.com
CC: yjf@stanford.edu, linux-kernel@vger.kernel.org,
       fuse-devel@lists.sourceforge.net, mc@cs.stanford.edu
In-reply-to: <0EFE5EBF-93C7-11D9-A59F-000393ACC76E@mac.com> (message from Kyle
	Moffett on Sun, 13 Mar 2005 08:51:54 -0500)
Subject: Re: [MC] [CHECKER] Need help on mmap on FUSE (linux user-land file system)
References: <Pine.GSO.4.44.0503122327090.7685-100000@elaine24.Stanford.EDU> <0EFE5EBF-93C7-11D9-A59F-000393ACC76E@mac.com>
Message-Id: <E1DAmi5-0001OI-00@dorka.pomaz.szeredi.hu>
From: Miklos Szeredi <miklos@szeredi.hu>
Date: Mon, 14 Mar 2005 11:22:05 +0100
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 759
Lines: 19

> > Forget to mention, we are checking linux 2.6.  It appears to us
> > that mmap doesnt' work for FUSE in linux 2.6.
> 
> IIRC, the reason mmap doesn't work on FUSE is because when it
> dirties pages they cannot be flushed reliably, because writing them
> out involves calling a userspace process which may allocate RAM,
> etc.

Yes.  To be precise this only affects writable shared mmap(), which is
not used by the great majority of applications.  Any other kind of
memory mapping should work OK.

Thanks,
Miklos
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