Re: [PATCH 1/2] handling 64bit values for st_ino]

[Peter Staubach]

Al Viro wrote:

> [My apologies, forgot to Cc the first half...]
>
> Date: Thu, 10 Nov 2005 00:27:29 +0000
> From: Al Viro <viro@xxxxxxxxxxxxxxxx>
> To: Linus Torvalds <torvalds@xxxxxxxx>
> Subject: [PATCH 1/2] handling 64bit values for st_ino
> User-Agent: Mutt/1.4.1i
>
> 	We certainly do not want 64bit kernel ino_t, since that would
> screw icache lookups for no good reason; fs with 64bit keys used to
> identify inodes can just use iget5().
>  

Has this potential degradation been measured?  This is a lot of extra
complexity which needs to justified by the resulting performance.

> 	Fix is pretty cheap and consists of two parts:
> 1) widen struct kstat ->ino to u64, add a macro (check_inumber()) to
> be used in callers of ->getattr() that want to store ->ino in possibly
> narrower fields and care about overflows (stuff like sys_old_stat() with
> its 16bit st_ino clearly doesn't ;-)

It seems to me that a type with a name which better matches the intended
semantics would be a better choice than u64.  Even something like ino64_t
would help file systems maintainers to correctly implement the appropriate
support.

   Thanx...

      ps
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