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

Theodore Tso wrote:
> We don't do this with the SCSI layer where we make a complete clone of
> the driver layer so that there is a /usr/src/linux/driver/scsi and
> /usr/src/linux/driver/scsi2, do we?  And we didn't do that with the
> networking layer either, as we added ipsec, ipv6, softnet, and a whole
> host of other changes and improvements.  
> 
> What we do instead is we have a series of patches, which can be made
> available in various experimental trees, and as they get more
> polishing and experience with people using it without any problems,
> they can get merged into the -mm tree, and then eventually, when they
> are deemed ready, into mainline.  That is also the normal Linux
> development process, and it's worked quite well up until now with ext3.

No, there is a key difference between ext3 and SCSI/etc.:  cruft is removed.

In ext3, old formats are supported for all eternity.


> Folks seem to be worried about ext3 being "too important to experiment
> with", but the fact remains, we've been doing continuous improvement
> with ext3 for quite some time, and it's been quite smooth.  The htree
> introduction was essentially completely painless, for example --- and

I disagree.  There were some distro annoyances as I recall.


> people liked the fact that they could get the features of indexed
> directories without needing to do a complete dump and restore of the
> filesystem.

Of course people always like new features.  :)

ext4 should allow you to deliver new features more rapidly, while 
keeping the existing ext3 happily stable.

	Jeff