virDomainSaveConfig calls virDomainDefFormat which was setting the caps
to NULL, thus keeping the old behaviour (i.e. not looking at
netprefix). This patch adds the virCapsPtr to the function and allows
the configuration to be saved and skipping interface names that were
registered with virCapabilitiesSetNetPrefix().
Signed-off-by: NJoao Martins <joao.m.martins@oracle.com>

Every single call to qemuDomainEventQueue() uses the following pattern:

    if (event)
        qemuDomainEventQueue(driver, event);

Let's move the check for valid event to qemuDomainEventQueue and
simplify all callers.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

This patch reverts commit 76c61cdc.

VIR_DOMAIN_DISK_MIRROR_STATE_ABORT says we asked for a block job to be
aborted rather than saying it was aborted. Let's just use
VIR_DOMAIN_DISK_MIRROR_STATE_NONE consistently whenever a block job
finishes since no caller depends on VIR_DOMAIN_DISK_MIRROR_STATE_ABORT
(anymore) to check whether a block job failed or it was cancelled.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

By switching block jobs to use domain conditions, we can drop some
pretty complicated code in NBD storage migration.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

The wrapper is useful for calling qemuBlockJobEventProcess with the
event details stored in disk's privateData, which is the most likely
usage of qemuBlockJobEventProcess.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

Most virDomainDiskIndexByName callers do not care about the index; what
they really want is a disk def pointer.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

qemuBlockJobSyncBegin and qemuBlockJobSyncEnd delimit a region of code
where block job events are processed "synchronously".
qemuBlockJobSyncWait and qemuBlockJobSyncWaitWithTimeout wait for an
event generated by a block job.

The Wait* functions may be called multiple times while the synchronous
block job is active. Any pending block job event will be processed by
only when Wait* or End is called.  disk->blockJobStatus is reset by
these functions, so if it is needed a pointer to a
virConnectDomainEventBlockJobStatus variable should be passed as the
last argument. It is safe to pass NULL if you do not care about the
block job status.

All functions assume the VM object is locked. The Wait* functions will
unlock the object for as long as they are waiting. They will return -1
and report an error if the domain exits before an event is received.

Typical use is as follows:

  virQEMUDriverPtr driver;
  virDomainObjPtr vm; /* locked */
  virDomainDiskDefPtr disk;
  virConnectDomainEventBlockJobStatus status;

  qemuBlockJobSyncBegin(disk);

  ... start block job ...

  if (qemuBlockJobSyncWait(driver, vm, disk, &status) < 0) {
      /* domain died while waiting for event */
      ret = -1;
      goto error;
  }

  ... possibly start other block jobs
      or wait for further events ...

  qemuBlockJobSyncEnd(driver, vm, disk, NULL);

To perform other tasks periodically while waiting for an event:

  virQEMUDriverPtr driver;
  virDomainObjPtr vm; /* locked */
  virDomainDiskDefPtr disk;
  virConnectDomainEventBlockJobStatus status;
  unsigned long long timeout = 500 * 1000ull; /* milliseconds */

  qemuBlockJobSyncBegin(disk);

  ... start block job ...

  do {
      ... do other task ...

      if (qemuBlockJobSyncWaitWithTimeout(driver, vm, disk,
                                          timeout, &status) < 0) {
          /* domain died while waiting for event */
          ret = -1;
          goto error;
      }
  } while (status == -1);

  qemuBlockJobSyncEnd(driver, vm, disk, NULL);
Signed-off-by: NMichael Chapman <mike@very.puzzling.org>

We will want to use synchronous block jobs from qemu_migration as well,
so split this function out into a new source file.
Signed-off-by: NMichael Chapman <mike@very.puzzling.org>