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Re: VOP_GETATTR: locking protocol change proposal


> The vnode locking requirement currently allows to call VOP_GETATTR()
> on an unlocked vnode.  This is orthogonal to all other operations that
> read data or metadata and want at least a shared lock.  It also asks
> for trouble as the attributes may change while the operation is in
> progress.
> With the attached diff the locking protocol requests at least a shared
> lock and all calls to VOP_GETATTR() outside of file systems respect it.
> The calls from file systems need review (NFS server is suspicious at least).
> I will commit this diff around Oct 14 if noone objects.

postgresql assumes instant lseek(SEEK_END) to get the size of
their heap files.

as fsync etc keeps the vnode lock during i/o, it might cause severe
performance regression.


> --
> Juergen Hannken-Illjes - - TU Braunschweig 
> (Germany)

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