Re: 2.5.28 and partitions

[Alexander Viro]

On Thu, 25 Jul 2002 [e-mail] wrote:

> Just saw some new partition code in 2.5.28. Good!
> I like almost all I see, except for one thing:
> 
> +struct parsed_partitions {
> +       char name[40];
> +       struct {
> +               unsigned long from;
> +               unsigned long size;
> +               int flags;
> +       } parts[MAX_PART];
> +       int next;
> +       int limit;
> +};
> 
> and I object to the long instead of u64 or so.

Separate set of patches.  As it is, struct hd_struct is still there and
still not modified.  And it has unsigned long.  It will become sector_t.

Actually, I'm not all that sure that we want u64 here.  The thing being,
start_sect shouldn't be bigger than sector_t (see how it's used).  And
64bit arithmetics on 32bit boxen sucks big way.  I'm not too concerned
about adding start_sect per se - it's done once per request and it's
noise compared to the rest of work.  However, long long for sector_t
will hit in a lot of more interesting code paths.

That stuff becomes an issue for 2Tb disks.  Do we actually have something
that large attached to 32bit boxen?
 
> With 2^32 sectors one can handle up to 2^41 bytes, 2 TiB.
> Already today people want RAIDs that are larger, and
> few years from now we'll have single disks that are larger.

... and still use i386 with these disks?  ia64 is stillborn, but x86-64
promises to be more useful than Itanic.

u64 for sector_t doesn't change anything for 64bit boxen that might be
interested in really large disks and screws 32bit ones that shouldn't
have to pay for that...