Arch Linux

Some (obscure) mount options are supported by ext[23], but not by ext4. If these are used with the latest kernel, the kernel will simply refuse to mount the fs.

This is particularly bad if it is the rootfs, as it will give you a read-only root, without the possibility of editing fstab to fix the issue. (Of course it can be done, but you have to get creative ;-) ). [-1]

I posted a patch to the ext4 list[0] that fixes the issue. It was acked by one of the maintainers, but don't has not been applied yet.

We should either backport this patch or revert the change to using ext4 (I obviously prefer the former).

[-1] https://bbs.archlinux.org/viewtopic.php?pid=1062947
[0] http://news.gmane.org/gmane.comp.file-systems.ext4