Re: [PATCH 1/2] qemu: introduce locking option for disk source of qemu

On Fri, Jan 22, 2021 at 21:32:05 -0500, Masayoshi Mizuma wrote: > From: Masayoshi Mizuma <m.mizuma(a)jp.fujitsu.com&gt; > > Introduce locking option for disk source of qemu. > It may be useful to avoid file lock issues. Lock issues usually mean that you are doing something wrong. > locking option supports three switches; 'auto', 'on' and 'off'. > The default behaivor will work if locking option isn't set. > > Example of the usage: > > <disk type='file' device='disk'> > <driver name='qemu' type='qcow2' cache='none'/> > <source file='/tmp/QEMUGuest1.img' locking='off'/> > <target dev='hda' bus='ide'/> > <address type='drive' controller='0' bus='0' target='0' unit='0'/> > </disk> > > Signed-off-by: Masayoshi Mizuma <m.mizuma(a)jp.fujitsu.com&gt; > --- > docs/schemas/domaincommon.rng | 9 +++++++++ > src/conf/domain_conf.c | 8 ++++++++ > src/conf/storage_source_conf.c | 9 +++++++++ > src/conf/storage_source_conf.h | 14 ++++++++++++++ > src/libvirt_private.syms | 1 + > src/qemu/qemu_block.c | 5 +++++ > 6 files changed, 46 insertions(+) Few quick notes: - I'm not entirely persuaded that we should at this at all - qemu locking works to prevent user mistakes - you really need to know what to expect if you use images which are used by multiple VMs - you really need to add some form of justification, the current one definitely is insufficient and thus I'm inclined to NACKing the concept of enabling setting of the locks completely