linux-kernel - Re: End of FAT directories

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Date:	Fri, 29 Apr 2011 00:44:16 +0900
From:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:	Michael Karcher <kernel@...rcher.dialup.fu-berlin.de>
Cc:	Pavel Machek <pavel@....cz>, dosfstools <daniel@...ian.org>,
	mtools <Alain@...ux.lu>, linux-kernel@...r.kernel.org
Subject: Re: End of FAT directories

Michael Karcher <kernel@...rcher.dialup.fu-berlin.de> writes:

> Am Donnerstag, den 28.04.2011, 15:25 +0200 schrieb Pavel Machek:
>> > >  For overwriting the
>> > > zeroed entry, why we have to check all entries until see next zeroed
>> > > (yeah, now, we allowed the crappy data after zeroed)?
>> > My point was not about checking all entries until the next zeroed entry,
>> > which is overcomplicating stuff. I meant that if we hit the end (i.e.
>> > the first zeroed entry) when searching for free slots, in that case we
>> > just clear the one entry directly following the inserted entries. This
>> > makes sure that no files magically appear. I *do* understand that
>> This sounds like a good idea, and costs nothing. I hope we can
>> convince Ogawa...
>
> I am going to implement that and publish a patch. If the patch is clean
> enough, maybe we can convince him. But the freedom of open source can't
> prevent me from using a patch like that, of course. And maybe it also
> helps when the patch gets some testing.

Of course, it's good to publish. However if you can't detect buggy or
corrupted directory, I wouldn't ack to help buggy stuff.

So it can be the mount option, but I can't see at all the point it is
in-kernel as FS.

>> Kernel should stop at zero invalid entry.

I'm not complaining to stop at zero. Rather I acked already if it didn't
overwrite after zeroed entry.

>> fsck should consider any garbage past zero entry as an error, and zero
>> it out. (Complaining about duplicate blocks is unhelpful but better
>> than nothing.  It should really zero the garbage out.)
>
> In fact, what you describe is something I would call "consistent". I was
> not implying that kernel and dosfsck should do exactly the same thing,
> but I was implying that the kernel and dosfsck should either both or
> none consider entries past the gap as existing file.
> Current state is: both consider past-gap entries valid. Your described
> state will be: none consider past-gap entries valid. The behaviour you
> describe is exactly what I would imagine as best way to go. Maybe fsck
> should ask for "shift post-gap entries/create a dummy deleted entry"
> vs. "clear post-gap entries".

Yes. Also my opinion is the fsck should get ack from user to overwrite
data or salvage (has possibility to salvage) if interactive mode, then
fixes it.

Thanks.
-- 
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
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