Re: [libvirt] [PATCH v2 6/7] domain_lock: Implement metadata locking
On Tue, Aug 14, 2018 at 01:19:42PM +0200, Michal Privoznik wrote:
In order for our drivers to lock resources for metadata change we
need set of new APIs. Fortunately, we don't have to care about
every possible device a domain can have. We care only about those
which can live on a network filesystem and hence can be accessed
by multiple daemons at the same time. These devices are covered
in virDomainLockMetadataLock() and only a small fraction of
those can be hotplugged (covered in the rest of the introduced
APIs).
I'm not sure I understand the rationale behind saying we only care
about resources on network filesystems.
If I have 2 locally running guests, and both have a serial port
backed by a physical serial port, eg
<serial type="dev">
<source path="/dev/ttyS0"/>
<target port="1"/>
</serial>
we *do* care about locking /dev/ttyS0, as libvirtd isn't doing
mutual exclusion checks anywhere else for the /dev/ttyS0 device
node.
In general I think we need to lock every single file resource
that is labelled for a guest, regardless of whether its local
or remote.
Regards,
Daniel
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