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Subject: Re: [PATCH] vfs: automount should ignore LOOKUP_FOLLOW
From: Ian Kent <raven@themaw.net>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
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Date: Fri, 09 Sep 2011 11:37:44 +0800
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On Thu, 2011-09-08 at 22:54 +0100, Al Viro wrote:
> On Thu, Sep 08, 2011 at 01:19:49PM -0700, Linus Torvalds wrote:
> 
> > >> I'm inclined to apply the patch as a regression fix, but I'll let this
> > >> thread try to convince me for another day..
> > >
> > > IIRC, that matches traditional SunOS behaviour and it actually does make
> > > sense; you want wildcard expansion and ls -l to be doable even when there's
> > > a stuck NFS server. ?IOW, non-triggering lstat(2) is a matter of usability...
> > 
> > non-triggering lstat() isn't the issue, afaik. We never trigger on lstat.
> > 
> > nontriggering *stat()* is the issue. We didn't *use* to trigger on
> > stat() either. Now in 2.6.38+ we do.
> 
> Yes.  Again, IIRC that's what SunOS implementation had been doing all along;
> I think the reason was that stat()+open()+fstat() getting different results
> for stat and fstat would spook quite a few programs, but I could be easily
> wrong on that.

Yes, that the sort of problem that we see.

For example, find(1) has had problems with this sort of inconsistency
with before and after comparisons it makes as it walks the directory
tree.

Ian