On Wed, Oct 16, 2013 at 12:13:43AM -0700, Christoph Hellwig wrote:
> On Tue, Oct 15, 2013 at 04:39:29PM -0400, J. Bruce Fields wrote:
> > From: "J. Bruce Fields" <bfields@xxxxxxxxxx>
> >
> > Once we've found any connected parent, we know all our parents are
> > connected--that's true even if there's a concurrent rename. May as well
> > clear them all at once.
> >
> > Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
>
> Looks good,
>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
>
> > 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);
> > + clear_disconnected(target_dir);
> > noprogress = 0;
> > } else if (pd == mnt->mnt_sb->s_root) {
> > printk(KERN_ERR "export: Eeek filesystem root is not connected, impossible\n");
>
> You might as well throw a patch in to make this condition a BUG_ON, it
> would indicate a nasty bug in the dcache and has never triggered in the
> last 10 years as far as I know.
We've seen some ugly crashes made uglier by unnecessary BUG()s. I guess
that wouldn't be the case here as we're not holding any critical locks
and all we're going to kill is an nfsd thread or open_by_handle caller.
And like you say it's a very unlikely case anyway.
So, OK, I'll turn this case into a BUG_ON in a separate patch.
--b.
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