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

["Warren Turkal" <wt@penguintechs.org>]

I have a drive that has the property of having the journal bit set and
having 0 in the journal_info_block field that mounts in rw on MacOS X.
That's how I discovered the problem.

wt

On Thu, Nov 27, 2008 at 8:21 AM, Roman Zippel <zippel@linux-m68k.org> wrote:
> 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
>