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

[Qi Yong]

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
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