Re: [PATCH 4/4] dcache: don't clear DCACHE_DISCONNECTED too early

[Christoph Hellwig <hch@infradead.org>]

On Mon, Sep 09, 2013 at 01:46:47AM +0100, Al Viro wrote:
> On Sat, Sep 07, 2013 at 02:46:01PM -0400, J. Bruce Fields wrote:
> > From: "J. Bruce Fields" <bfields@redhat.com>
> > 
> > DCACHE_DISCONNECTED should not be cleared until we're sure the dentry is
> > connected all the way up to the root of the filesystem.  It *shouldn't*
> > be cleared as soon as the dentry is connected to a parent.  That will
> > cause bugs at least on exportable filesystems.
> 
> Then you probably want this
>                 if (!IS_ROOT(pd)) {
>                         /* must have found a connected parent - great */
>                         spin_lock(&pd->d_lock);
>                         pd->d_flags &= ~DCACHE_DISCONNECTED;
>                         spin_unlock(&pd->d_lock);
>                         noprogress = 0;
> to go through all intermediates, clearing DCACHE_DISCONNECTED on all of
> them; O(depth^2) can suck when we have a long chain of directories...

Aka call reconnect_path() from fs/exportfs/expfs.c on it.