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

Michael Poole wrote:
> Jeff Garzik writes:
> 
>> Andrew Morton wrote:
>>> Ted&co have been pretty good at avoiding compatibility problems.
>> Well, extents and 48bit make that track record demonstrably worse.
>>
>> Users are now forced to remember that, if they write to their
>> filesystem after using either $mmver or $korgver kernels, they are
>> locked out of using older kernels.
> 
> Users are also forced to remember that, if they use certain new
> distros or programs, they are locked out of using older kernels.  They
> are forced to remember that if they have certain newer hardware, they
> are locked out of using older kernels.  They are forced to remember
> that if they use ext3 (or XFS or JFS) _at all_ they are locked out of
> using older kernels.  Why single out this particular aspect of limited
> forward compatibility to harp on so much?

Because it's called backwards compat, when it isn't?
Because it is very difficult to find out which set of kernels you are 
locked out of?
Because the filesystem upgrade is stealthy, occurring as it does on the 
first data write?

	Jeff