linux-kernel - Re: [PATCH 14/25] ubifs: Add authentication nodes to journal

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Date:   Thu, 30 Aug 2018 15:41:03 +0200
From:   Sascha Hauer <s.hauer@...gutronix.de>
To:     Richard Weinberger <richard@....at>
Cc:     linux-mtd@...ts.infradead.org, David Gstir <david@...ma-star.at>,
        kernel@...gutronix.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 14/25] ubifs: Add authentication nodes to journal

On Wed, Aug 29, 2018 at 04:54:30PM +0200, Richard Weinberger wrote:
> Am Mittwoch, 29. August 2018, 16:38:34 CEST schrieb Sascha Hauer:
> > On Mon, Aug 27, 2018 at 10:48:26PM +0200, Richard Weinberger wrote:
> > > >  	release_head(c, BASEHD);
> > > >  	kfree(dent);
> > > > +	ubifs_add_dirt(c, lnum, ubifs_auth_node_sz(c));
> > > 
> > > You have to account it immediately because while a commit you have no longer
> > > a reference to them?
> > > Upon replay you should have since you scan LEBs anyway.
> > 
> > What do you mean here? Is that a suggestion to change something?
> 
> I don't fully understand how you keep the lprops dirty counter correct for
> auth nodes. Hence the question.
> 
> Auth nodes are not referenced by the index, so you have to keep track of
> them manually.

Yes. That's why I call ubifs_add_dirt(c, lnum, ubifs_auth_node_sz(c))
each time I create an auth node.

> Is your current approach "mark them dirty immediately and rely on LPT commit"
> to not get lost of an auth node?

Yes, I mark the auth nodes dirty in the assumption that the correct
values are written on a LPT commit.

> 
> I expected auth nodes getting dirtied also during journal reply.

Yes, this happens in replay.c replay_bud(). "used" gets increased with
every node found except when it's an auth node. Here "used" is not
increased, the result is that the auth node adds to the dirty space.

Sascha

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