From mboxrd@z Thu Jan  1 00:00:00 1970
From: Hin-Tak Leung <htl10@users.sourceforge.net>
Subject: hfsplus foldercount (Re: hfsplus BUG(), kmap and journalling.)
Date: Fri, 2 Nov 2012 05:43:41 +0000 (GMT)
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Cc: linux-fsdevel@vger.kernel.org,
	Till Kamppeter <till.kamppeter@gmail.com>,
	Naohiro Aota <naota@elisp.net>
To: Vyacheslav Dubeyko <slava@dubeyko.com>
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--- On Tue, 30/10/12, Vyacheslav Dubeyko <slava@dubeyko.com> wrote:

<snipped>
> [snip]
> > BTW, I think I see another bug - unrelated to
> journalling - in the current hfs+=20
> > code: folder counts are not updated correctly. It seems
> that hfs+ folders have=20
> > recursive folder counts (i.e. a parent dir knows how
> many sub-dir's it has,=20
> > without needing to recurse down), and this is currently
> not updated correctly.=20
> > One way of demo'ing this is to:
> >=20
> >=A0 =A0=A0=A0(make sure fs is fsck-clean ;
> mount)
> >=20
> >=A0 =A0=A0=A0cp -ipr
> somedir_with_some_files/ some_hfs+_place/someplace_inside/
> >=20
> >=A0 =A0=A0=A0(umount; run fsck_hfs again,
> now it complains about folder counts)
> >=20
> > The actual message looks a it like this:
> >=20
> > ** Checking catalog hierarchy.
> >=A0 =A0=A0=A0HasFolderCount flag needs to be
> set (id =3D 393055)
> >=A0 =A0=A0=A0(It should be 0x10 instead of
> 0)
> >=A0 =A0=A0=A0Incorrect folder count in a
> directory (id =3D 205)
> >=A0 =A0=A0=A0(It should be 18 instead of
> 17)
>=20
> Sorry, I can't reproduce this issue. I tried to reproduce as
> you
> described. Maybe, do you miss something?

Since it is easily producible for me, I thought I'd have a look one day=
=2E.. got side-tracked to look at Apple's xnu kernel's file system driv=
er on journal, and turned out to be interesting. Just grep -R -i folder=
count shows, among other things, a very important comment:

bsd/hfs/hfs_vfsutils.c:	/* kHFSHasFolderCount is only supported/updated=
 on HFSX volumes */

So the foldercount feature is "optional" and only switched on for the c=
asesitive variant of HFS+ . Yes, while my primary interests is in journ=
alling, for inter-operation with linux, I somewhat naively always chose=
 to format my test volumes as HFSX, rather than the the plain case-pres=
erving-but-not-sensitive variant, not knowing there are important diffe=
rences.

I'll find some time to have a look at what else is hiding in Apple's xn=
u kernel code... there are probably more interesting "optional" but imp=
ortant differences.

Hin-Tak
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