[libvirt] [PATCH 1/2] LXC: add support for --config in setmaxmem command

[chenhanxiao at cn.fujitsu.com]

> -----Original Message-----
> From: Michal Privoznik [mailto:mprivozn at redhat.com]
> Sent: Thursday, July 24, 2014 5:00 PM
> To: Chen, Hanxiao/陈 晗霄; libvir-list at redhat.com
> Subject: Re: [libvirt] [PATCH 1/2] LXC: add support for --config in setmaxmem
> command
> 
> On 16.07.2014 11:51, Chen Hanxiao wrote:
> > In lxc, we could not use setmaxmem command
> > with --config options.
> > This patch will add support for this.
> >
> > Signed-off-by: Chen Hanxiao <chenhanxiao at cn.fujitsu.com>
> > ---
> >   src/lxc/lxc_driver.c | 69
> ++++++++++++++++++++++++++++++++++------------------
> >   1 file changed, 46 insertions(+), 23 deletions(-)
> >
> > diff --git a/src/lxc/lxc_driver.c b/src/lxc/lxc_driver.c
> > index b7b4b02..be6ee19 100644
> > --- a/src/lxc/lxc_driver.c
> > +++ b/src/lxc/lxc_driver.c
> > @@ -721,10 +721,10 @@ static int lxcDomainSetMemoryFlags(virDomainPtr dom,
> unsigned long newmem,
> >       virLXCDomainObjPrivatePtr priv;
> >       virLXCDriverPtr driver = dom->conn->privateData;
> >       virLXCDriverConfigPtr cfg = NULL;
> > -    unsigned long oldmax = 0;
> >
> >       virCheckFlags(VIR_DOMAIN_AFFECT_LIVE |
> > -                  VIR_DOMAIN_AFFECT_CONFIG, -1);
> > +                  VIR_DOMAIN_AFFECT_CONFIG |
> > +                  VIR_DOMAIN_MEM_MAXIMUM, -1);
> >
> >       if (!(vm = lxcDomObjFromDomain(dom)))
> >           goto cleanup;
> > @@ -743,32 +743,55 @@ static int lxcDomainSetMemoryFlags(virDomainPtr dom,
> unsigned long newmem,
> >                                           &persistentDef) < 0)
> >           goto cleanup;
> >
> > -    if (flags & VIR_DOMAIN_AFFECT_LIVE)
> > -        oldmax = vm->def->mem.max_balloon;
> > -    if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
> > -        if (!oldmax || oldmax > persistentDef->mem.max_balloon)
> > -            oldmax = persistentDef->mem.max_balloon;
> > -    }
> > +    if (flags & VIR_DOMAIN_MEM_MAXIMUM) {
> > +        if (flags & VIR_DOMAIN_AFFECT_LIVE) {
> > +            if (newmem < vm->def->mem.cur_balloon) {
> > +                virReportError(VIR_ERR_OPERATION_INVALID, "%s",
> > +                           _("Cannot resize the max memory less than current"
> > +                             " memory for an active domain"));
> > +                goto cleanup;
> > +            }
> > +            vm->def->mem.max_balloon = newmem;
> 
> Are things that easy? Don't we need to communicate this with the
> lxc_controler somehow? Even though you allow only extending, I think
> unless we are 100% sure guest will see the resize, we shouldn't allow this.
> 
I focused on '--config', 
so I kept what the original lxcDomainSetMaxMemory did.
It looks that guest could not see the resize, and we shouldn't allow this.

> > +        }
> >
> > -    if (newmem > oldmax) {
> > -        virReportError(VIR_ERR_INVALID_ARG,
> > -                       "%s", _("Cannot set memory higher than max memory"));
> > -        goto cleanup;
> > -    }
> > +        if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
> > +            sa_assert(persistentDef);
> 
> Is this assert needed? Did clang complain or is this just a pure lefover
> from copying from qemu_driver.c?
> 
> > +            persistentDef->mem.max_balloon = newmem;
> > +            if (persistentDef->mem.cur_balloon > newmem)
> > +                persistentDef->mem.cur_balloon = newmem;
> > +            if (virDomainSaveConfig(cfg->configDir, persistentDef) < 0)
> > +                goto cleanup;
> > +        }
> > +    } else {
> > +        unsigned long oldmax = 0;
> >
> > -    if (flags & VIR_DOMAIN_AFFECT_LIVE) {
> > -        if (virCgroupSetMemory(priv->cgroup, newmem) < 0) {
> > -            virReportError(VIR_ERR_OPERATION_FAILED,
> > -                           "%s", _("Failed to set memory for domain"));
> > -            goto cleanup;
> > +        if (flags & VIR_DOMAIN_AFFECT_LIVE)
> > +            oldmax = vm->def->mem.max_balloon;
> > +        if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
> > +            if (!oldmax || oldmax > persistentDef->mem.max_balloon)
> > +                oldmax = persistentDef->mem.max_balloon;
> >           }
> > -    }
> >
> > -    if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
> > -        sa_assert(persistentDef);
> 
> Well, since it has been here already, I think we can leave it in your
> patch too.
> 
> > -        persistentDef->mem.cur_balloon = newmem;
> > -        if (virDomainSaveConfig(cfg->configDir, persistentDef) < 0)
> > +        if (newmem > oldmax) {
> > +            virReportError(VIR_ERR_INVALID_ARG,
> > +                           "%s", _("Cannot set memory higher than max memory"));
> >               goto cleanup;
> > +        }
> > +
> > +        if (flags & VIR_DOMAIN_AFFECT_LIVE) {
> > +            if (virCgroupSetMemory(priv->cgroup, newmem) < 0) {
> > +                virReportError(VIR_ERR_OPERATION_FAILED,
> > +                               "%s", _("Failed to set memory for domain"));
> > +                goto cleanup;
> > +            }
> > +        }
> > +
> > +        if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
> > +            sa_assert(persistentDef);
> > +            persistentDef->mem.cur_balloon = newmem;
> > +            if (virDomainSaveConfig(cfg->configDir, persistentDef) < 0)
> > +                goto cleanup;
> > +        }
> >       }
> >
> >       ret = 0;
> >
> 
> But what I miss in this patch is, what would:
> 
> virDomainSetMaxMemoryFlags(dom, newmem, VIR_DOMAIN_AFFECT_CURRENT |
> VIR_DOMAIN_MEM_MAXIMUM)
> 
> do? I mean, the _CURRENT is not translated to _LIVE or _CONFIG anywhere
> in the function.

I put that section in 2/2 patch.
I'll add a description in v2.

Thanks,
- Chen