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Re: tstile syndrome

On Sep 1, 2009, at 9:32 AM, David Holland 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. The reason that you don't end up copy- pasting 30 copies, etc. is because it gives you a chance to dump the completely irrational locking protocol that currently exists.

-- thorpej

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