On Thu, Mar 09, Balbir Singh wrote:
> > +/*
> > + * If we slept on waiting for other prunes to finish, there maybe are
> > + * some dentries the d_lru list that we have "overlooked" the last
> > + * time we called select_parent(). Therefor lets restart in this case.
> > + */
> > void shrink_dcache_parent(struct dentry * parent)
> > {
> > int found;
> > + struct super_block *sb = parent->d_sb;
> >
> > + again:
> > while ((found = select_parent(parent)) != 0)
> > prune_dcache(found);
> > +
> > + /* If we are called from generic_shutdown_super() during
> > + * umount of a filesystem, we want to check for other prunes */
> > + if (!sb->s_root && wait_on_prunes(sb))
> > + goto again;
> > }
>
> cosmetic - could we do this with a do { } while() loop instead of a goto?
>
> I think though that after select_parent(), wait_on_prunes() can sleep just
> once, so we do not need a goto. Just calling wait_on_prunes() should
> fix the race. For all the dentries missed in the race, wait_on_parent()
> will ensure that they are dput() by prune_one_dentry() before wait_on_parent()
> returns.
>
> But, I do not have anything against the goto, so this patch should be just
> fine.
>
No. Think about a dentry which parent isn't unhashed. This parent will end up
on the lru-list after the wait_on_prunes(). Therefore we have to do the
select_parent()/prune_dcache() again to get rid of all dentries.
And I missed the "goto vs. do...while()" against my colleagues here, too ;)
I'll send a followup.
> > if (root) {
> > sb->s_root = NULL;
> > - shrink_dcache_parent(root);
> > shrink_dcache_anon(&sb->s_anon);
> > + shrink_dcache_parent(root);
> > dput(root);
>
> This change might conflict with the NFS patches in -mm.
>
Hmm, right. Andrew, if you want a rediff against -mm just tell me. I'm
actually diff'ing against lates linux-2.6.git.
Regards,
Jan
--
Jan Blunck [email protected]
SuSE LINUX AG - A Novell company
Maxfeldstr. 5 +49-911-74053-608
D-90409 Nürnberg http://www.suse.de
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