On 08/03/2017 10:02 AM, Kevin Wolf wrote: > BDRV_O_ALLOW_RDWR is a flag that tells whether qemu can internally > reopen a node read-write temporarily because the user requested > read-write for the top-level image, but qemu decided that read-only is > enough for this node (a backing file). > > bdrv_reopen() is different, it is also used for cases where the user > changed their mind and wants to update the options. There is no reason > to forbid making a node read-write in that case.
Hmm, I wonder. https://bugzilla.redhat.com/show_bug.cgi?id=1465320 details a failure when starting qemu with a read-write NBD disk, then taking several snapshots (nbd <- snap1 <- snap2 <- snap3), then where intermediate commit (snap2 into nbd) works but live commit (snap3 into nbd) fails with a message that nbd does not support reopening. I'm presuming that your series may help to address that; I'll give it a spin and see what happens. But first, the code review: > > Signed-off-by: Kevin Wolf <kw...@redhat.com> > --- > include/block/block.h | 3 ++- > block.c | 11 +++++++---- > 2 files changed, 9 insertions(+), 5 deletions(-) > Reviewed-by: Eric Blake <ebl...@redhat.com> -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
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