Re: [libvirt] [PATCH v1 06/11] network: Create real network status files
On 30.11.2012 20:04, Laine Stump wrote:
On 11/19/2012 11:51 AM, Michal Privoznik wrote:
> Currently, we are only keeping a inactive XML configuration
> in status dir. This is no longer enough as we need to keep
> this class_id attribute so we don't overwrite old entries
> when the daemon restarts.
Aha! So you're looking at solving the problem in a different way - save
everything to the status file rather than recomputing it as you restart.
While I like the idea of having the network status file hold this
information, I think its reliability is suspect. What if a guest's
process is terminated while libvirtd isn't running? Or what if libvirtd
exits unexpectedly after the commands to setup bandwidth have been
executed, but before the new network state file has been written (or
vice versa, depending on the code).
Also, networks aren't properly shut down when the host is being shutdown
(there's no equivalent to the libvirt-guests service, although at least
one person a month or two ago requested it).
If guest is being shut down, the networkReleaseActualDevice() is called,
isn't it? And this should update the floor_sum. Even if libvirtd is
restarted and qemu process dies meanwhile, qemuProcessStop is called and
this calls the networkReleaseActualDevice() so I think we are safe here.
If everybody agrees that saving this info to a file and re-reading it on
start up is reliable, though, then we might as well do the same thing
with the device pool (although it's currently a bit different - the
inuse count is stored in the virNetworkDef rather than Obj, and is
reported during net-dumpxml)
With new code we can update this.
> However, since there has already
> been a libvirt release
*a* libvirt release? :-)
That 'a' belongs to 'release'. It doesn't matter which release it
was.
Yeah, now that I re-read it again it's a mess :)
> which has just <network/> as root element,
> and we want to keep things compatible, detect that loaded
> status file is older one, and don't scream about it.
> ---
> src/conf/network_conf.c | 199 ++++++++++++++++++++++++++++++++++---------
> src/conf/network_conf.h | 2 +
> src/libvirt_private.syms | 1 +
> src/network/bridge_driver.c | 9 +--
> 4 files changed, 165 insertions(+), 46 deletions(-)
>
ACK.