Change in vdsm[master]: vm: update volume apparentsize after snapshot

Ayal Baron has posted comments on this change.

Change subject: vm: update volume apparentsize after snapshot
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Patch Set 3: (1 inline comment)

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File vdsm/libvirtvm.py
Line 2121:         # (the apparentsize is updated as last step in updateDriveParameters)
Line 2122:         self.stopDisksStatsCollection()
Line 2123: 
Line 2124:         try:
Line 2125:             while True:
The while loop here is just complicating things.  First, there are at most 2 runs.
Second, the only common denominator between the two runs is a single line - snapshotCreateXML.

How about removing it and doing something like (less code, less indentation and less complexity imo):

try:
    try:
        self._dom.snapshotCreateXML(snapxml, snapFlags)
    except Exception as e:
        # try again without the VIR_DOMAIN_SNAPSHOT_CREATE_QUIESCE flag.
        # At the moment libvirt is returning two generic errors
        # (INTERNAL_ERROR, ARGUMENT_UNSUPPORTED) which are too
        # broad to be caught (BZ#845635).
        snapFlags &= (~libvirt.VIR_DOMAIN_SNAPSHOT_CREATE_QUIESCE)
        # Here we don't need a full stacktrace (exc_info) but
        # it's still interesting knowing what was the error
        self.log.debug("Snapshot failed using the quiesce flag, trying "
                       "again without it (%s)", e)
        try:
            self._dom.snapshotCreateXML(snapxml, snapFlags)
        except Exception as e:
            self.log.error("Unable to take snapshot", exc_info=True)
            return errCode['snapshotErr']

# Update the drive information
    for drive in newDrives.values():
        self.updateDriveParameters(drive)

finally:
  self.startDisksStatsCollection()
Line 2126:                 try:
Line 2127:                     self._dom.snapshotCreateXML(snapxml, snapFlags)
Line 2128:                 except Exception as e:
Line 2129:                     # If we used VIR_DOMAIN_SNAPSHOT_CREATE_QUIESCE and the

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Gerrit-MessageType: comment
Gerrit-Change-Id: I472c2931551643914e6a09b54d3d96f371f34864
Gerrit-PatchSet: 3
Gerrit-Project: vdsm
Gerrit-Branch: master
Gerrit-Owner: Federico Simoncelli 
Gerrit-Reviewer: Ayal Baron 
Gerrit-Reviewer: Dan Kenigsberg 
Gerrit-Reviewer: Federico Simoncelli 
Gerrit-Reviewer: oVirt Jenkins CI Server