I had my laptop hanging and my wife simply pressed the power button to turn it off, now I can't boot as it fails with kernel panic.
My fs is btrfs on ssd with discard mount option.
The error I'm getting on kernel panic is:
BTRFS: failed to read log tree
BTRFS: open_ctree failed

As wiki page https://btrfs.wiki.kernel.org/index.php/Btrfs-zero-logsuggests, I tried to run btrfs-zero-log but it failed with:

Check tree block failed, want=49500766208, have=0
Check tree block failed, want=49500766208, have=0
Check tree block failed, want=49500766208, have=0
Check tree block failed, want=49500766208, have=0
Check tree block failed, want=49500766208, have=0
read block failed check_tree_block
Couldn't setup log root tree

Same wiki page suggests that I might need to patch btrfs if its prior to 3.15 but mine is 3.17, so I'm kinda stuck here... 

Also btrfs-image is not working either, with same messages, plus:
Open ctree failed
create failed (Success)

However I can see files via grub cli, so I guess it's not completely ruined...