Problems mounting HFS+ partitions for writing

[Rick Buitenman <rickmb@xs4all.nl>]

Several Gentoo ppc users (including myself) are reporting the problem of
suddenly only being able to mount their hfs+ partitions read-only.

dmesg says:
HFS+-fs warning: Filesystem was not cleanly unmounted, running
fsck.hfsplus is recommended. leaving read-only

A little googling tells me this problem is not unique to one single
distribution:

http://www.redhat.com/archives/fedora-devel-list/2004-January/msg00711.html
http://jodok.muellers.ms/linuxppc/
http://forums.gentoo.org/viewtopic.php?t=119954
http://linux.derkeiler.com/Newsgroups/comp.os.linux.development.system/2003-11/0019.html

fsck.hfsplus doesn't seem to exist in any distribution (?)
Remounting only seems to work in some cases.
Fixing the partition from OSX doesn't solve the problem.
The partition remains writable under OSX directly and via MOL.

In some cases the problem simply disappears for no apparent reason.

Since this is where the real ppc-guru's hang out, I thought I'd ask
around here.