Re: [Ext2-devel] [RFC 0/13] extents and 48bit ext3

Qi Yong
2006-06-20T06:15:34Z

Linus Torvalds wrote:

>On Fri, 9 Jun 2006, Stephen C. Tweedie wrote:
>
>
>>When is the Linux syscall interface enough? When should we just bump it
>>and cut out all the compatibility interfaces?
>>
>>No, we don't; we let people configure certain obsolete bits out (a.out
>>support etc), but we keep it in the tree despite the indirection cost to
>>maintain multiple interfaces etc.
>>
>>
>
>Right. WE ADD NEW SYSTEM CALLS. WE DO NOT EXTEND THE OLD ONES IN WAYS THAT
>MIGHT BREAK OLD USERS.
>
>Your point was exactly what?
>
>Btw, where did that 2TB limit number come from? Afaik, it should be 16TB
>for a 4kB filesystem, no?
>
>

Partition tables describe partitions in units of one sector.
2^(32+9) = 2T

To prevent integer overflow, we should use only 31 bits of a 32-bit integer.
2^(31+12) = 8T

There's _terrible_ hacks to really get to 16T.

-- qiyong