Ubuntu and Live USB won't Boot after power cut 15.04 BTRFS

Question

I didn't think this was a problem until it happened to me twice on two different systems and have never seen this before.

First time I was running Xubuntu 15.04 on a Lenovo T61 using BTRFS. The battery was shot and I had a spare so I decided to do a hot swap while it was running. I guess I forgot the power, pulled out the battery and it shuts down. Afterward it won't boot, I just get black screen and nothing else. I figured it was a bad hard drive or shoddy RAM. This is a 1 hour old OS install so I figure I might as well reinstall. Load the disk in, select to reinstall, black screen nothing loads. RAM problem? I take out the RAM in the laptop, look for replacements but I don't have anything that old. I put it back in anyway, restart, and finally the Live DVD Xubuntu loads again. Weird...

Now, I'm running 15.04 on a dell laptop (btrfs too). I decided I want to try Kubuntu on it for kicks and extra functionality. It was acting real sluggish so I killed the power because I hate waiting. Yeah that's probably not kosher but my windows partition loads just fine. After booting back up, the Live USB Kubuntu won't load, nor will Ubuntu that's on the hard disk. I retry a couple times, tried the advance boot options. One gives me "Initializing RAM disk" and hangs. Others just black screen.

This problem might be the weirdest thing I've ever seen.

Answer 1

Figured it out, mostly. It's a bug with BTRFS. Check here: https://bbs.archlinux.org/viewtopic.php?id=195524

Answer 2

Ever since I switched to 15.04, also when I have an unclean boot, the system hangs saying it couldn't find the root btrfs volume, which I found quite strange and I think it might be related to this issue.

My setup is a bit complex and the layout is hand-made since the installer can't do this: I have an unencrypted /boot partition, then the rest of the disk is occupied by a LUKS partition containing a LVM PV with a VG containing two logical volumes: one for the root(formatted as btrfs with a subvolume for /home) and one for swap.

I usually 'solve' it by rebooting with the 3.16 kernel that I had in 14.10, which seems to always work. Unfortunately people who just installed 15.04 from scratch don't have this option.