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Re: VOP_WRITE without vnode lock

On Thu, Aug 07, 2008 at 11:38:48AM -0400, der Mouse wrote:
> > Is it safe (regarding data consistency) to VOP_WRITE() to a vnode
> > without holding the vnode lock when:
> > [...]
> > - Data written is always the same that would have been read before.
> I'm curious - why do the write at all, if you know this is the case?

Part of ffs snapshot renovation. When a block gets written we have to save
it on the snapshot vnode. So for a snapshot reader the data does not change
while the on-disk position of the data changes.

Juergen Hannken-Illjes - - TU Braunschweig 

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