BTRFS_IOC_DEV_INFO

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.
extern (C)
enum BTRFS_IOC_DEV_INFO = _IOWR!(btrfs_ioctl_dev_info_args)(BTRFS_IOCTL_MAGIC, 30);

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