linux-kernel - Re: [PATCH 0/7] Permit filesystem local caching and NFS superblock sharing [try #13]

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Date:	Tue, 05 Sep 2006 20:20:17 +0800
From:	Ian Kent <raven@...maw.net>
To:	David Howells <dhowells@...hat.com>
Cc:	Trond Myklebust <trond.myklebust@....uio.no>,
	Andrew Morton <akpm@...l.org>, torvalds@...l.org,
	steved@...hat.com, linux-fsdevel@...r.kernel.org,
	linux-cachefs@...hat.com, nfsv4@...ux-nfs.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/7] Permit filesystem local caching and NFS superblock
	sharing [try #13]

On Tue, 2006-09-05 at 11:37 +0100, David Howells wrote:
> Ian Kent <raven@...maw.net> wrote:
> 
> > > As long as you don't rely on stat...mkdir working.  That can go wrong if the
> > > dentry gets booted from the dcache by memory pressure in the "...".
> > 
> > I'm not clear on your point here.
> 
> I was wondering if you were going to rely on stat() forcing the dentry to be
> correctly initialised before you did mkdir(), but it seems not.
> 
> > If I stat a path and it exists then all is good and I'm done.
> > If I stat a path and I get something other than ENOENT then all is bad
> > and I return fail.
> > Otherwise I can just attempt to create the directory and fail if all is
> > bad with that.
> 
> Okay, I suppose.  But that still doesn't seem to deal with the case of creating
> a directory on the client that then overlays a symlink on the server that you
> can't yet access.

We're largely performing user space actions at this point.
Wouldn't the subsequent call to mount(8) catch that?

> 
> You may also get ENOENT because you stat a symlink, though you'll get EEXIST
> from mkdir, even if there's nothing at the far end.

Don't think this is something I need to care about either.
I can't mount on a symlink so the error return would be the correct way
to deal with it.

Ian


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