Description of problem:

A specific live merge can leave volumes in an illegal state, e.g. as a result of BZ 1314082.

In this case the merge actually completes on the host, but the merged volumes are not removed from with the storage domain or the database.

If the VM were to be restarted in this state, it would restart successfully with the active volume of each disk now being the original leaf volume, i.e. the one merged from and the one that should have been previously removed.

This can result in out-of-date data blocks being accessed, if the parent volume had been written to after the merge had completed.

If a subsequent merge is performed, again potentially out-of-date blocks might be merged back.


Version-Release number of selected component (if applicable):

RHEV 3.6.4
RHEL 7.2 host;
   vdsm-4.17.23-0.el7ev


How reproducible:

Every time.


Steps to Reproduce:
1. Encounter BZ 1314082.
2. Restart the VM.

OR:

1. Create a VM with one disk.
2. Create a snapshot.
3. Modify the database to set the base image's imagestatus = 4 (illegal).
4. On the SPM host, change the 'LEGALITY' field in the volume metadata for the leaf volume to "ILLEGAL".
5. Start the VM.


Actual results:

VM starts up with an 'out-of-date' active volume.


Expected results:

VM not allowed to start.


Additional info: