Re: VFS 64-bit clean? Not yet (was Re: large-file-system)

Linus Torvalds (torvalds@transmeta.com)
21 Feb 1998 21:33:54 GMT

In article <199802212047.PAA01146@netcom.ca>, <aem@netcom.ca> wrote:
>> The rest of us would like to NOT see performance go to hell.
>> It would be nice to be able to master a DVD disk. That requires
>> only 2 to 4 bits more than we have now. Going with signed sectors
>> would be 9 more bits. Remember, this is exponential expansion.
>
>[DVD uses UDF v1.2]
>You need 47-bit inode numbers for UDF: 16-bit partition,
>31-bit block. If you throw in an offset too, that's another
>11-bits (2k blocks) at least.

That's not strictly true: you don't need 47-bit inode numbers, you need
a 47-bit or larger "file handle" the same way NFS has a 256-bit file
handle.

Which is not to say that a 64-bit inode number should be dismissed as
one way of implementing things, but I think that it tends to be a lot
more efficient to throw some thought at a problem before you try to fix
it with brute strength. Almost always the brute-strength approach ("add
more bits", in this case) is the wrong one.

Linus

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