Re: [PATCH 07/11] exportfs: Allow filehandle lookup to cross internal mount points.

["NeilBrown" <neilb@suse.de>]

On Thu, 29 Jul 2021, J. Bruce Fields wrote:
> On Wed, Jul 28, 2021 at 08:37:45AM +1000, NeilBrown wrote:
> > @@ -232,6 +239,68 @@ reconnect_path(struct vfsmount *mnt, struct dentry *target_dir, char *nbuf)
> >  	}
> >  	dput(dentry);
> >  	clear_disconnected(target_dir);
> 
> Minor nit--I'd prefer the following in a separate function.

Fair.  Are you thinking "a separate function that is called here" or "a
separate function that needs to be called by whoever called
exportfs_decode_fh_raw()" if they happen to want the vfsmnt to be
updated?

NeilBrown

> 
> --b.
> 
> > +
> > +	/* Need to find appropriate vfsmount, which might not exist yet.
> > +	 * We may need to trigger automount points.
> > +	 */
> > +	path.mnt = mnt;
> > +	path.dentry = target_dir;
> > +	vfs_getattr_nosec(&path, &stat, 0, AT_STATX_DONT_SYNC);
> > +	target_dev = stat.dev;
> > +
> > +	path.dentry = mnt->mnt_root;
> > +	vfs_getattr_nosec(&path, &stat, 0, AT_STATX_DONT_SYNC);
> > +
> > +	while (stat.dev != target_dev) {
> > +		/* walk up the dcache tree from target_dir, recording the
> > +		 * location of the most recent change in dev number,
> > +		 * until we find a mountpoint.
> > +		 * If there was no change in show_dev result before the
> > +		 * mountpount, the vfsmount at the mountpoint is what we want.
> > +		 * If there was, we need to trigger an automount where the
> > +		 * show_dev() result changed.
> > +		 */