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

From: Jeff Garzik
Date: Fri Jun 09 2006 - 14:55:51 EST


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



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