Backref error

[Hegyi László <laci200270@xxxxxxxxx>]

Hello guys!

I have a 2TB disk formatted to btrfs.My notebook broke last may, so I 
haven't used it in a long time, only to backup a few files, but from a 
windows pc(using windows btrfs driver), and maybe (i don't remember) put 
a few files to the disk.Then my thinkpadlinux-btrfs@xxxxxxxxxxxxxxx 
arrived, and tried to backup from my ssd from the reinstall.Got some 
random error, after a few hours of reading random forum posts I resolved 
it with zero-log.The error occurred a few times, always resolved it with 
zero log.Then yesterday i tried to write to it got a different error( 
https://pastebin.com/ZxNWaFX8 ) tried the usual zero log didn't helped, 
okay forum post reading suggested to do btrfs repair 
--init-extent-tables now that command is running utilizing one of my CPU 
cores 100% and only doing I/O access once in a few minutes(according to 
the HDD caddy indicator).Dev stats didn't say any errors, nor btrfs 
repair only a space cache mismatch https://pastebin.com/eJh4EBx9 any 
ideas? Also shall I cancel the init extent trees or just wait until 
finishes?And how much time shall it take?It spams my console output like 
this https://pastebin.com/6LjjXuin. Thank you for all of your help and 
sorry if my grammar is bad my native language isn't English