On Tue, Jan 17, 2012 at 03:05:29PM +0100, Kevin Wolf wrote: > Am 17.01.2012 14:50, schrieb Marcelo Tosatti: > > On Tue, Jan 17, 2012 at 02:27:04PM +0100, Kevin Wolf wrote: > >> Am 13.01.2012 14:14, schrieb Stefan Hajnoczi: > >>> From: Marcelo Tosatti <mtosa...@redhat.com> > >>> > >>> Add support for streaming data from an intermediate section of the > >>> image chain (see patch and documentation for details). > >>> > >>> Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com> > >>> Signed-off-by: Stefan Hajnoczi <stefa...@linux.vnet.ibm.com> > >> > >> I'm afraid that in the review for the previous version I couldn't see > >> the wood for the trees... This does limit the COR requests issued by > >> image streaming, but not those issued by the guest. Am I missing > >> something? This is not what we want, is it? > > > > What you mean "limit the COR requests"? > > base -> sn1 -> sn2 > > You only want to copy the content of sn1 into sn2 and keep base. The > streaming coroutine is doing the right thing because it checks > is_allocated_base. However, if it is the guest that reads some data from > base, COR copies it into sn2 even though it's in the common base file.
Ah, yes. > Maybe streaming shouldn't enable normal COR on images, but instead of > calling bdrv_co_read it could directly call bdrv_co_copy_on_readv(). That would work.
