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Re: tstile syndrome

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,

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.



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