Change in vdsm[master]: snapshot: Start the snapshot module

fromani at redhat.com fromani at redhat.com
Thu Jul 2 10:53:10 UTC 2015


Francesco Romani has posted comments on this change.

Change subject: snapshot: Start the snapshot module
......................................................................


Patch Set 6:

(1 comment)

https://gerrit.ovirt.org/#/c/43018/6//COMMIT_MSG
Commit Message:

Line 10: include only the GuestAgent class, responsible for freezing and thawing
Line 11: guest file systems during a snapshot.
Line 12: 
Line 13: Freezing or thawing filesystems can fail because of many reasons;
Line 14: libvirt driver does not support freezing, guest agent is not installed
> under what conditions libvirt driver do not support it?
in our case, it seems pretty simple (and pretty scary):

  static int
  qemuDomainSnapshotFSFreeze(virQEMUDriverPtr driver ATTRIBUTE_UNUSED,
                             virDomainObjPtr vm,
                             const char **mountpoints,
                             unsigned int nmountpoints)
  {
      qemuDomainObjPrivatePtr priv = vm->privateData;
      int frozen;

      if (!qemuDomainAgentAvailable(vm, true))
          return -1;

      qemuDomainObjEnterAgent(vm);
      frozen = qemuAgentFSFreeze(priv->agent, mountpoints, nmountpoints);
      qemuDomainObjExitAgent(vm);
      return frozen < 0 ? -2 : frozen;
  }
Line 15: or not running or guest agent failure. We detect the first two cases, and
Line 16: treat any other libvirt error as guest agent failure.
Line 17: 
Line 18: The errors are reported back to engine so it can handled them correctly.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I8e4c54f461039de99823c3b80a10be0a960c4273
Gerrit-PatchSet: 6
Gerrit-Project: vdsm
Gerrit-Branch: master
Gerrit-Owner: Nir Soffer <nsoffer at redhat.com>
Gerrit-Reviewer: Adam Litke <alitke at redhat.com>
Gerrit-Reviewer: Allon Mureinik <amureini at redhat.com>
Gerrit-Reviewer: Dan Kenigsberg <danken at redhat.com>
Gerrit-Reviewer: Daniel Erez <derez at redhat.com>
Gerrit-Reviewer: Francesco Romani <fromani at redhat.com>
Gerrit-Reviewer: Jenkins CI
Gerrit-Reviewer: Maor Lipchuk <mlipchuk at redhat.com>
Gerrit-Reviewer: Martin Polednik <mpolednik at redhat.com>
Gerrit-Reviewer: Michal Skrivanek <michal.skrivanek at redhat.com>
Gerrit-Reviewer: Nir Soffer <nsoffer at redhat.com>
Gerrit-Reviewer: Vinzenz Feenstra <vfeenstr at redhat.com>
Gerrit-Reviewer: automation at ovirt.org
Gerrit-HasComments: Yes


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