[libvirt] [PATCH 11/15] qemu: domain: Add private data for NBD migration storage source definition

[Peter Krempa]

On Tue, May 22, 2018 at 20:26:56 -0400, John Ferlan wrote:
> 
> 
> On 05/18/2018 07:29 AM, Peter Krempa wrote:
> > Allow saving various aspects necessary to do NBD migration via blockdev
> > by storing a 'virStorageSource' in the disk private data meant to store
> > the NBD target of migration. Along with this add code to parse and
> > format it into the status XML.
> > 
> > Signed-off-by: Peter Krempa <pkrempa at redhat.com>
> > ---
> >  src/qemu/qemu_domain.c | 162 ++++++++++++++++++++++++++++++++++++++++++++++---
> >  src/qemu/qemu_domain.h |   1 +
> >  2 files changed, 156 insertions(+), 7 deletions(-)
> > 
> > diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
> > index 94a9c5d1bc..632c025bef 100644
> > --- a/src/qemu/qemu_domain.c
> > +++ b/src/qemu/qemu_domain.c
> 
> [...]
> 
> 
> > 
> > @@ -2092,6 +2155,7 @@ qemuDomainObjPrivateXMLFormatJob(virBufferPtr buf,
> >      virBuffer attrBuf = VIR_BUFFER_INITIALIZER;
> >      virBuffer childBuf = VIR_BUFFER_INITIALIZER;
> >      qemuDomainJob job = priv->job.active;
> > +    int ret = -1;
> > 
> >      if (!qemuDomainTrackJob(job))
> >          job = QEMU_JOB_NONE;
> > @@ -2115,13 +2179,23 @@ qemuDomainObjPrivateXMLFormatJob(virBufferPtr buf,
> >      if (priv->job.asyncJob != QEMU_ASYNC_JOB_NONE)
> >          virBufferAsprintf(&attrBuf, " flags='0x%lx'", priv->job.apiFlags);
> > 
> > -    if (priv->job.asyncJob == QEMU_ASYNC_JOB_MIGRATION_OUT)
> > -        qemuDomainObjPrivateXMLFormatNBDMigration(&childBuf, vm);
> > +    if (priv->job.asyncJob == QEMU_ASYNC_JOB_MIGRATION_OUT &&
> > +        qemuDomainObjPrivateXMLFormatNBDMigration(&childBuf, vm) < 0)
> > +        goto cleanup;
> > 
> >      if (priv->job.migParams)
> >          qemuMigrationParamsFormat(&childBuf, priv->job.migParams);
> > 
> > -    return virXMLFormatElement(buf, "job", &attrBuf, &childBuf);
> > +    if (virXMLFormatElement(buf, "job", &attrBuf, &childBuf) < 0)
> > +        goto cleanup;
> > +
> > +    ret = 0;
> > +
> > + cleanup:
> > +    virBufferFreeAndReset(&attrBuf);
> > +    virBufferFreeAndReset(&childBuf);
> 
> So I assume the lack of FreeAndReset was existing prior to this patch
> since d8be0f4bc?

Yes. I assumed that virXMLFormatElement clears them on error, but it
apparently does not, so adding them here actually fixes a possible bug.

This chagne would be necessary even with the above assumption being
valid as this patch adds a possible error code path.
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