Bug In ext4 in kernels > 2.6.39 - Not mounting with arguments/options I specify in fstab on root remount

[Matt Parnell <mparnell@gmail.com>]

Hi all... I usually run my system the zen kernel (zen-kernel.org), but
I've tried this with the default Archlinux kernel (pretty much a
vanilla build) as well and for some reason, the root drive won't mount
with the options I desire on anything above .29 The drive is an SSD,
and this is really getting on my nerves. I've looked at the
initscripts, fstab, everything else, and I just can't get any of this
to work properly. It was mounting with all the options I specified in
2.6.39, but since some change to the kernel (or something else?) I
can't mount with my options anymore. On top of this all, I've tried
using both /dev/root and /dev/sdb1, but for some reason the kernel's
only wanting to use /dev/root - I'm wondering if there's some kind of
conflict due to that symlink...

I know this isn't my initscripts, as I've also tried this using
openrc, aside from the default arch init system, and because upon
downgrading to 2.6.39 everything is working normally again, I know it
is the kernel. Information:

grub.cfg:

linux	/boot/linux-zen root=/dev/sdb1 ro rootfstype=ext4
rootflags=data=writeback noatime barrier=0 discard noinitrd

fstab:

/dev/sdb1 / ext4 data=writeback,noatime,nodiratime,barrier=0,discard 0 1

Upon attempting to remount manually, I only get the following when I
try to use the options I specified above:

EXT4-fs (sdb1): Cannot change data mode on remount

Interestingly, this also happened and worked, which I think is a bug,
how can barrier=0 and 1 at the same time?

EXT4-fs (sdb1): re-mounted. Opts: user_xattr,barrier=1,barrier=0

I'm currently using a .39 kernel and can live with it for now, but I
thought this was serious enough that the ext4 devs should hear about
it. If you need any more information, just let me know.

Thanks!

Matt Parnell