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	Sat, 20 Jan 2024 01:38:59 +0000
Date: Sat, 20 Jan 2024 01:38:59 +0000
From: Al Viro <viro@zeniv.linux.org.uk>
To: Andreas Gruenbacher <agruenba@redhat.com>
Cc: gfs2@lists.linux.dev
Subject: Re: [PATCH 0/9] gfs2: Bugs in "Use GL_NOBLOCK flag for non-blocking
 lookups"
Message-ID: <20240120013859.GA2207555@ZenIV>
References: <20240119212056.805617-1-agruenba@redhat.com>
 <20240120013639.GB2087318@ZenIV>
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Sender: Al Viro <viro@ftp.linux.org.uk>

On Sat, Jan 20, 2024 at 01:36:39AM +0000, Al Viro wrote:
> On Fri, Jan 19, 2024 at 10:20:47PM +0100, Andreas Gruenbacher wrote:
> > Hello,
> > 
> > Al Viro has reported issues with commit dd00aaeb3432 ("gfs2: Use
> > GL_NOBLOCK flag for non-blocking lookups"):
> > 
> > * First, parent can now be NULL and dereferencing it in
> >   gfs2_dir_check(d_inode(parent), &dentry->d_name, ip) isn't going to
> >   work;
> 
> Nit: parent can't be NULL; what can be NULL in RCU mode is d_inode(parent) when
> sampled inside ->d_revalidate().  IOW, it's not d_inode(parent) evaluation
> that breaks, but passing the resulting NULL inode pointer to gfs2_dir_check().

Nevermind, the way it's written parent will be NULL in RCU case.  Sorry about
the noise.