[PATCH 02/18] fs: add get_acl helper

[Christoph Hellwig]

On Thu, Dec 12, 2013 at 08:06:09PM +0100, Andreas Gruenbacher wrote:
> > +	/*
> > +	 * A filesystem can force a ACL callback by just never filling the
> > +	 * ACL cache. But normally you'd fill the cache either at inode
> > +	 * instantiation time, or on the first ->get_acl call.
> > +	 *
> > +	 * If the filesystem doesn't have a get_acl() function at all, we'll
> > +	 * just create the negative cache entry.
> > +	 */
> > +	if (!inode->i_op->get_acl) {
> > +		set_cached_acl(inode, type, NULL);
> > +		return ERR_PTR(-EAGAIN);
> 
> The function should return NULL here.

Indeed.  EAGAIN is the convention check_acl() in fs/namei.c uses,
but it will return that automatically if we just return NULL here.