As described in my previous comment, the fs was available in read-write mode again.
I added another disk to the btrfs and with the additional space I was able to rerun and successfully finish the btrfs balance operation (as described in https://www.slicewise.net/debian/balancierung-eines-vollen- btrfs-dateisystems/ ): btrfs balance start x Done, had to relocate 2797 out of 2797 chunks So my file system is completely rescued now. To sum it up: There is no way I could reproduce this error again with a recent kernel. All I can say is that Kernel 4.2.0-27.32~14.04.1-generic 4.2.8-ckt1 ran into unexpected behaviour when doing a btrfs balance: Expected Result: Error "enospc errors during balance" (at least) Actual Result: Kernel bug in dmesg, Filesystem goes read-only, Input/Output errors occur, many directories are not readable even in read-only mode, even ls does not work. It seems as if the system totally screwed it up. Suggested Fix: All of these problems should be avoidable because the later reboot "healed" them (Error "enospc errors during balance" reported, fs mounted read-write, but btrfs balance still fails, which is totally fine at this point) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1559723 Title: soft lockup during btrfs balance To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1559723/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
