On 03/14/2016 09:44 AM, Kevin Wolf wrote: > Writethrough mode is going to become a BlockBackend feature rather than > a BDS one, so forbid it in places where we won't be able to support it > when the code finally matches the envisioned design. > > We only allowed setting the cache mode of non-root nodes after the 2.5 > release, so we're still free to make this change. > > The target of block jobs is now always opened in a writeback mode > because it doesn't have a BlockBackend attached. This makes more sense > anyway because block jobs know when to flush. If the graph is modified > on job completion, the original cache mode moves to the new root, so > for the guest device writethough always stays enabled if it was > configured this way. > > Signed-off-by: Kevin Wolf <kw...@redhat.com> > --- > block.c | 7 ++++ > blockdev.c | 19 ++++++++- > tests/qemu-iotests/142 | 50 +++++++++++------------ > tests/qemu-iotests/142.out | 98 > +++++++++------------------------------------- > 4 files changed, 68 insertions(+), 106 deletions(-) >
Reviewed-by: Eric Blake <ebl...@redhat.com> > +++ b/tests/qemu-iotests/142 > @@ -96,36 +96,36 @@ function check_cache_all() > # bs->backing > > echo -e "cache.direct=on on none0" Pre-existing, but 'echo -e' is non-portable (even in bash, you can set options such that it changes behavior). printf is better, if we're worried about it. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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