Re: [PATCH 0/9] gfs2: Bugs in "Use GL_NOBLOCK flag for non-blocking lookups"

[Al Viro <viro@zeniv.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.