Messages in this thread | | | Date | Thu, 9 Mar 2006 12:00:25 +0100 | From | Jan Blunck <> | Subject | Re: [PATCH] Fix shrink_dcache_parent() against shrink_dcache_memory() race (updated patch) |
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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 jblunck@suse.de SuSE LINUX AG - A Novell company Maxfeldstr. 5 +49-911-74053-608 D-90409 Nürnberg http://www.suse.de - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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