ubuntu@ubuntu:/tmp$ sudo btrfsck --repair /dev/dm-0 
enabling repair mode
Checking filesystem on /dev/dm-0
UUID: 98835533-e5aa-493a-98e7-c251172f7923
checking extents
cmds-check.c:3730: check_owner_ref: Assertion `rec->is_root` failed.
btrfs check[0x41d6cf]
btrfs check[0x41d6f3]
btrfs check[0x420711]
btrfs check[0x4210cc]
btrfs check[0x421b7a]
btrfs check(cmd_check+0xe2e)[0x423b93]
btrfs check(main+0x13b)[0x40e4a7]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0)[0x7f01748e5a40]
btrfs check(_start+0x29)[0x40e4d9]
ubuntu@ubuntu:/tmp$