> + * io_uring block file commands, see IORING_OP_URING_CMD. > + * It's a different number space from ioctl(), reuse the block's code 0x12. > + */ > +#define BLOCK_URING_CMD_DISCARD _IO(0x12, 0) Please just start out at some arbitrary boundary, but don't reuse the ioctl code from an ioctl that does something vaguely similar for no good reason. The rest looks good.