On 04/06/2012 01:08 AM, Paolo Bonzini wrote:
Il 06/04/2012 06:36, Eric Blake ha scritto:
> If only qemu could get 'drive-reopen' inside 'transaction'...
Just a quick answer to this: if qemu could get 'drive-reopen' inside
'transaction', the standalone command could be made safe just as easily.
In fact, in QEMU 1.1 the blockdev-snapshot-sync command got a similar
treatment: it became transactionable, _and_ the standalone command
became a simple wrapper around a 1-command transaction.
Good point. So unless we have a situation where we want to do
'drive-reopen' on multiple disks at once, we don't actually have to use
a transaction command to reopen a single disk. Meanwhile, for
similarity with blockdev-snapshot-sync, it looks like I will someday be
adding a VIR_DOMAIN_BLOCK_JOB_ABORT_ATOMIC flag, which fails if qemu
lacks support for reopen within a transaction, and assuming that qemu
exposes a way to see which commands are transactionable.
--
Eric Blake eblake(a)redhat.com +1-919-301-3266
Libvirt virtualization library
http://libvirt.org