https://man7.org/linux/man-pages/man3/posix_fallocate.3.html#ERRORS:
> EOPNOTSUPP
> The filesystem containing the file referred to by fd does not support
> this operation. This error code can be returned by C libraries that
> don't perform the emulation shown in NOTES, such as **musl libc**.
I've encountered this problem on Alpine Linux running inside an LXC
container on Ubuntu with data on ZFS.