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Date: Fri, 1 Aug 2008 11:03:59 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Neil Brown <neilb@suse.de>
Subject: Re: [RFC] Reinstate NFS exportability for JFFS2.
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On Fri, Aug 01, 2008 at 12:14:17PM +1000, Neil Brown wrote:

> It sounds to me like the core problem here is that the locking regime
> imposed by the VFS simply isn't suitable for JFFS2 .. and a bunch of
> other filesystems.
> 
> This seems to suggest that the VFS should be changed.
> Superficially, it seems that changing the locking rules so that the
> callee takes i_mutex rather than the caller taking it would help and,
> in the case of JFFS2, make f->sem redundant.  Does that match your
> understanding?

Huh?  How could that possibly help?  You are not changing the sequence
of operations on locks, you only slightly modify the timing; how could
that possibly eliminate a deadlock?  Moreover, how the _hell_ could
making exclusion area smaller make f->sem redundant?