Re: New experimental btrfs branch ready for testing

[Chris Mason <chris.mason@oracle.com>]

On Mon, Jun 01, 2009 at 05:04:47PM -0400, Chris Mason wrote:
> Hello everyone,
> 
> Yan Zheng has been doing some major surgery to the back references and
> extent allocation code, tackling bottlenecks in the code that tracks
> extents.  It scales better with many snapshots and performs better in
> the common case of no snapshots at all.
> 
> THE NEW CODE IS A FORWARD ROLLING DISK FORMAT CHANGE.  This means it is
> compatible with the current btrfs disk format, but once you mount a
> filesystem with the new code, it WILL NO LONGER BE MOUNTABLE FROM OLD
> KERNELS.  Old kernels spit out an error message when you try them on new
> format filesystems.

Just a quick note that I'm having some issues with the backward
compatibility code on 32 bit kernels.  It can still read all the old
items but it is having problems with creating new backrefs.

32bit is working fine on an entirely new format FS, and my 64 bit box
can read and write the old format FS just fine.  I'm hoping to track
this one down today, but it would be a good idea to wait if you want to
try the new code on old filesystems on 32 bit machines.

If you do hit crashes, please don't immediately reformat your FS if you
can avoid it.  We should be able to fix most problems people hit.

-chris