VFS ROADMAP (and vfs01.patch stage 1 available for testing)

Allan Fields bsd at afields.ca
Fri Aug 13 16:43:14 PDT 2004

On Thu, Aug 12, 2004 at 06:19:40PM -0700, Matthew Dillon wrote:
>     This represents the first of the many stages that will be needed to
>     thread the VFS subsystem.  I am going to have commit the work
>     incrementally, stage by stage, to keep the number of bugs to a minimum.
> 	fetch http://leaf.dragonflybsd.org/~dillon/vfs01.patch
>     Some testing would be appreciated.  This patch will go in tomorrow.
>     --
>     The really nasty stuff starts at stage 3.  Before I can implement the
>     messaging interface I have to:

So I guess people can expect a little bit of instability in the
vnode interface for the next while (-- meaning frequent changes not
necessarily bugs).. ;)

> 	* VM objects will become mandatory for all filesystems and will
> 	  also be made directly accessible to the kernel without having
> 	  to enter the VFS layer (ultimately this will result in greatly
> 	  improved read() and write() performance).
> 	* Implement a bottom-up cache invalidation abstraction for 
> 	  namespace, attribute, and file data, so layered filesystems
> 	  work properly.

This could support a write to either the lower layer or the upper
layer and cache would be coherent between layers?

>     This is a pretty ambitious plan, it could take me into next year to 
>     finish it all but when it is done we will be extremely well positioned
>     for the ultimate goal of implementing fully transparent clustering.
> 						-Matt

 Allan Fields, AFRSL - http://afields.ca
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