Rcently needed to mount my hfsplus formatted external disk on my Raspberry Pi. I would get a
mount: warning: ext_disk/ seems to be mounted read-only.
Finally I figured out that doing a
fsck.hfsplus on the disk and remounting worked well.
The steps I took:
$ sudo apt-get install hfsplus hfsutils hfsprogs $ fsck.hfsplus -f /dev/sdaX $ mount -o force /dev/sdaX /mnt/