From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nick Piggin Subject: Re: [patch 01/28] fs: d_validate fixes Date: Fri, 19 Nov 2010 16:01:08 +1100 Message-ID: <20101119050108.GB3284@amd> References: <20101116140900.039761100@kernel.dk> <20101116142028.254946611@kernel.dk> <20101118.125123.241932424.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: npiggin@kernel.dk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: David Miller Return-path: Content-Disposition: inline In-Reply-To: <20101118.125123.241932424.davem@davemloft.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Thu, Nov 18, 2010 at 12:51:23PM -0800, David Miller wrote: > From: Nick Piggin > Date: Wed, 17 Nov 2010 01:09:01 +1100 > > > d_validate has been broken for a long time. > > > > kmem_ptr_validate does not guarantee that a pointer can be dereferenced > > if it can go away at any time. Even rcu_read_lock doesn't help, because > > the pointer might be queued in RCU callbacks but not executed yet. > > > > So the parent cannot be checked, nor the name hashed. The dentry pointer > > can not be touched until it can be verified under lock. Hashing simply > > cannot be used. > > > > Instead, verify the parent/child relationship by traversing parent's > > d_child list. It's slow, but only ncpfs and the destaged smbfs care > > about it, at this point. > > > > Signed-off-by: Nick Piggin > > This won't apply because is conflicts with Christoph Hellwig's > RCU conversion of d_validate(). > > Which is a change that went in more than a month ago. Sorry yeah I had a local revert that I didn't send out, otherwise it should be a vanilla upstream kernel. > Thus I'd really appreciate if you mentioned what tree your patches are > against in your "0/N" posting, always. Try to remember. I'll put some time into polishing up a git tree and submitting the more interesting patches as well, this weekend. Thanks, Nick