On 2020/1/16 上午8:34, Michael Ruiz wrote:
> Hi,
>  I have a //@swap subvolume and i have a swapfile within it. I mount the 
> subvolume like such in fstab:
> 
> `rw,ssd,nofail,noautodefrag,nodatacow,nodatasum,subvolid=1234,subvol=/@swap`
> 
> It mounts correctly, but 1/15/20 4:20 PM kernel I get: 
> 
> `BTRFS warning (device dm-0): swapfile must not be copy-on-write`
> 
> I did chattr +C on the empty swapfile as per arch wiki instructions. The only 
> problem is that it does not work after reboot... Does btrfs allow subvolumes 
> to have different mount options?

If that file has nodatacow, then it may be possible that you had a
snapshot of that subvolume, and caused problem.

Thanks,
Qu