Re: [PATCH 2/2] Fix journal detection on HFS+.

[Roman Zippel <zippel@linux-m68k.org>]

Hi,

On Tue, 25 Nov 2008, Warren Turkal wrote:

> On Sat, Nov 22, 2008 at 8:52 PM, Roman Zippel <zippel@linux-m68k.org> wrote:
> > I'm curious how common it is to have the journal bit set but no journal block,
> > I haven't seen this case so far.
> 
> It's so uncommon that the technote for HFS+ doesn't mention it.
> However, I did find [1], and it's (c) by Apple. Look at the comment at
> [2] to see what tipped me off.

That likely also means the journal bit is cleared. If you want to verify 
this, you should check the actual kernel source and there I can't find 
anywhere, that they handle a zero journal block specially, thus it will 
result in a failure to replay the journal, so I don't see why we should 
allow write access to the volume in this case.

> > IMO more useful would be to read the journal block and check if there is
> > anything that needs to be replayed.
> > If you're interested in a second step you could replay the journal, it's not
> > that difficult to do, it's pretty much just copying blocks around.
> 
> I am actually looking into doing the journal replaying, but i haven't
> gotten around to it yet.

That's why I suggested to do the replay check first, as it's relatively 
simple to do.

bye, Roman