Anthony Liguori <aligu...@us.ibm.com> wrote: > Image files have two types of data: immutable data that describes things like > image size, backing files, etc. and mutable data that includes offset and > reference count tables. > > Today, image formats aggressively cache mutable data to improve performance. > In > some cases, this happens before a guest even starts. When dealing with live > migration, since a file is open on two machines, the caching of meta data can > lead to data corruption. > > This patch addresses this by introducing a mechanism to invalidate any cached > mutable data a block driver may have which is then used by the live migration > code. > > NB, this still requires coherent shared storage. Addressing migration without > coherent shared storage (i.e. NFS) requires additional work. > > Signed-off-by: Anthony Liguori <aligu...@us.ibm.com>
For the NFS case, we just need 2 different case: - outgoing: nothing to do (generic code already do an fsync()) - incoming: we need to reopen the image. For the rest, I agree. Once told that, I can implement my changes here. Later, Juan.
