linux-kernel - Re: [PATCH 0/2] vfs: ensure that dentries are revalidated on open (try #2)

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Date:	Wed, 11 Nov 2009 17:26:10 +0900
From:	Trond Myklebust <trond.myklebust@....uio.no>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	Jeff Layton <jlayton@...hat.com>, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, linux-nfs@...r.kernel.org,
	ebiederm@...ssion.com, adobriyan@...il.com,
	viro@...IV.linux.org.uk, jamie@...reable.org
Subject: Re: [PATCH 0/2] vfs: ensure that dentries are revalidated on open
 (try #2)

On Wed, 2009-11-11 at 08:57 +0100, Miklos Szeredi wrote:
> On Tue, 10 Nov 2009, Jeff Layton wrote:
> > This is the second attempt to fix this problem. The first one attempted
> > to fix this in procfs, but Eric Biederman pointed out that file bind
> > mounts have a similar problem. This set attempts to fix the issue at a
> > higher level, in the generic VFS layer.
> 
> I suspect the correct fix would be to clean up the open API so that
> NFSv4 doesn't have to hack its stateful open routine into the
> ->lookup() and ->d_revalidate() methods.

I've been working on that. I hope to have patches soon...

> Having said that, doing revalidation for proc symlinks and bind mounts
> (and not just for opens) might make sense.  This is something similar
> to FS_REVAL_DOT, so perhaps make it conditional on this flag (or a
> new, appropriately named one).

Aren't both proc symlinks and bind mounts pretty much guaranteed to
point to a valid dentry? Once we fix the open case, I can't see that we
need to do much more. Networked filesystems may want to revalidate the
inode attributes, but not the dentry itself...

Cheers
  Trond

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