Re: tstile syndrome

[Adam Hamsik <haaaad%gmail.com@localhost>]

Hi,
On Sep,Sunday 13 2009, at 11:26 PM, David Holland wrote:

> On Fri, Sep 11, 2009 at 03:14:09PM -0700, Jason Thorpe wrote:
> > > Such as? Please give clear examples. Moving the locks to below the  
> > > VFS
> > > layer does not change any of the ordering constraints or any of the
> > > hard problems (vnode recycle, rename, etc.) but only forces cutting
> > > and pasting 30 copies of what was previously FS-independent code  
> > > into
> > > every FS.
> >
> > Not true at all.  In Mac OS X, there is no exposed vnode-level  
> > locking
> > at the VFS layer or in the VFS<->file system interface.  Everything  
> > is
> > handled at the lower layers.
>
> How does this simplify the hard problems (vnode recycle, rename,
> etc.)?

I think that ZFS is nice example how rename can be handled look at  
zfs_rename.

> Please give clear examples.
>
> Also, how does it work with layers? And how do you make atomic
> create/mkdir work correctly?

I think that you should provide working example, because AFAIK current  
locking scheme doesn't work e.g. unionfs. Asking others to prove that  
their solution works, when it doesn't work, now doesn't seems right to  
me. In ZFS almost all locking was pushed to the FS level and it works.

Regards

Adam.