[Linux-cachefs] Re: [PATCH 7/5] Optimise d_find_alias()

[Al Viro]

On Fri, Mar 03, 2006 at 03:45:52AM -0800, Andrew Morton wrote:
> David Howells <dhowells at redhat.com> wrote:
> >
> >  struct dentry * d_find_alias(struct inode *inode)
> >   {
> >  -	struct dentry *de;
> >  -	spin_lock(&dcache_lock);
> >  -	de = __d_find_alias(inode, 0);
> >  -	spin_unlock(&dcache_lock);
> >  +	struct dentry *de = NULL;
> >  +	if (!list_empty(&inode->i_dentry)) {
> >  +		spin_lock(&dcache_lock);
> >  +		de = __d_find_alias(inode, 0);
> >  +		spin_unlock(&dcache_lock);
> >  +	}
> >   	return de;
> >   }
> 
> How can we get away without a barrier?

What would it buy you?