Re: [PATCH] struct loop_info64

[Linus Torvalds]

On Fri, 18 Apr 2003 [e-mail] wrote:
> +struct loop_info64 {
> +	int		   lo_number;		/* ioctl r/o */
> +	unsigned long long lo_device; 		/* ioctl r/o */
> +	unsigned long	   lo_inode; 		/* ioctl r/o */
> +	unsigned long long lo_rdevice; 		/* ioctl r/o */

Make these be explicitly sized, and try to put the 64-bit members at the 
beginning to avoid alignment and structure packing problems. Ie something 
more like

	struct loop_info64 {
		u64	lo_device;
		u64	lo_rdevice;
		u64	lo_inode;
		u32	lo_number;
		...

> +	int		   lo_offset;

Any reason to keep an "offset" as "int"? It should probably be "u64" as 
well.

If you call a structure "info64", make the fact that it's 64-bit
_explicit_. That way it will look and work the same on things like x86 and
x86-64, without the need to have translation layers for binary
compatibility.

We should literally have the rule that any user-visible data structures 
cannot use _any_ types other than u8/u16/u32/u64 (and _maybe_ the signed 
ones, if there is any real reason to).

		Linus