UFS2 (was Re: Junior kernel hacking)

[David Rhodus]

I'm not sure we want to do snapshots inside the filesystem
the way FreeBSD did them by modifying the UFS/FFS layer.
With the current VFS messaging work being done we'll be
abel perform the domain boundary at the messaging line.
We en-term will take each filesystem into a single thread. Then
taking all the VOP's and queueing them onto a single thread
representing the filesystem. Using the messaging infrastructure
as the boundary will enable use to queue all incoming messages
and wait for the undergoing I/O to finish.
Since that is actually something with a dependancy that is not
yet complete then another way to look at achieving what I'm
sure your really going for is avoiding having to fsck on an unclean
shutdown. I estimate with two or three complete 16 hour days of
work one could integrate the journaling code from Apple. It has
been nicely self-contained for us. You can download the files
here...
http://machdep.com/drhodus/vfs_journal.c
http://machdep.com/drhodus/vfs_journal.h
-DR

On Jan 14, 2004, at 2:17 AM, Kip Macy wrote:

Backporting snapshots would also be nice.

			-Kip

On Tue, 13 Jan 2004, Jeffrey Hsu wrote:

Depending on your degree of comfort working on filesystem code, a good
project is backporting the UFS2 size extensions.
							Jeffrey