Re: VFS

Andrew E. Mileski (aem@netcom.ca)
Sun, 16 Nov 1997 17:32:28 -0500 (EST)


[CC'd to linux-kernel and linux_udf]

> I was wondering, is using memory adresses as inode numbers portable to
> 64-bit architectures?

An excellent question! :-) I hope you don't mind it I share the answer.

Virtual inode numbers are completely portable to any architecture.

There are far less than 4GB of inodes on even the largest system.
Truncating a LARGE addresss [say 256-bits] to even the lower 32-bits
would not cause problems. Even with a wrap it will never wrap far
enough to cause a problem, because the inodes are in the kernel
memory space, which is far less than 4GB in size [typically a few MB].

To be precise:
NR_INODE < (((ino_t) ~0) / sizeof(struct inode))

--
Andrew E. Mileski   mailto:aem@netcom.ca