On 09/14/2010 04:47 AM, Avi Kivity wrote:
On 09/13/2010 04:34 PM, Anthony Liguori wrote:
On 09/13/2010 09:13 AM, Kevin Wolf wrote:
I think the only real advantage is that we fix NFS migration, right?
That's the one that we know about, yes.
The rest is not a specific scenario, but a strong feeling that
having an
image opened twice at the same time feels dangerous.
We've never really had clear semantics about live migration and
block driver's life cycles. At a high level, for live migration to
work, we need the following sequence:
1) src> flush all pending writes to disk
2) <barrier>
3) dst> invalidate any cached data
4) dst> start guest
That's pretty complicated, compared to
1) src> close
1.5) <barrier>
2) dst> open
3) dst> start guest
You need to make sure the open happens *after* the close.
You're just using close to flush all pending writes or open to
invalidate any cached data.