Re: [PATCH] nvme: add a compat_ioctl handler for NVME_IOCTL_SUBMIT_IO

[Christoph Hellwig]

> +static int nvme_compat_ioctl(struct block_device *bdev, fmode_t mode,
> +		unsigned int cmd, unsigned long arg)
> +{
> +	if (cmd == NVME_IOCTL_SUBMIT_IO32)
> +		return nvme_ioctl(bdev, mode, NVME_IOCTL_SUBMIT_IO, arg);

I think this really need a comment explaining what is going on, including
why not translating anything works in this specific case.

> +
> +	return nvme_ioctl(bdev, mode, cmd, arg);
> +}

This function should also be under CONFIG_COMPAT, with a

#define nvme_compat_ioctl	NULL

in the #else branch.

> index d99b5a772698..52699a26b9b3 100644
> --- a/include/uapi/linux/nvme_ioctl.h
> +++ b/include/uapi/linux/nvme_ioctl.h
> @@ -24,6 +24,21 @@ struct nvme_user_io {
>  	__u16	appmask;
>  };
>  
> +struct nvme_user_io32 {
> +	__u8	opcode;
> +	__u8	flags;
> +	__u16	control;
> +	__u16	nblocks;
> +	__u16	rsvd;
> +	__u64	metadata;
> +	__u64	addr;
> +	__u64	slba;
> +	__u32	dsmgmt;
> +	__u32	reftag;
> +	__u16	apptag;
> +	__u16	appmask;
> +} __attribute__((packed));

This should not be exposed in the UAPI header.  I think it should just
go into the #ifdef CONFIG_COMPAT block in core.c near the comment and
the compat_ioctl handler.