Deletion of a VolumeSnapshot object can causes deletion of a unbound VolumeSnapshotContent

[yuxiangqian]

checkContentAndBoundStatus returns four values:

1. the content (NOT necessarily bound to the given VS)
2. content's deletion policy == Delete, a boolean
3. content bound to given snapshot, a boolean
4. any error

processSnapshotWithDeletionTimestamp calls checkContentAndBoundStatus, then calls checkandRemoveSnapshotFinalizersAndCheckandDeleteContent without verifying binding

[yuxiangqian]

/assign

[yuxiangqian]

/cc @xing-yang

[xing-yang]

Reproduced it:

• create a dynamic snapshot (VS1) from a PVC, this should lead to the controller to create a VolumeSnapshotContent( VSC1)
• Update VSC1's VolumeSnapshotRef such that it points to a different VolumeSnapshot with name VS2, UID left to be empty.
• create a pre-provisioned snapshot (VS2) which points VSC1, the two should bind.
• readyToUse from VS1 becomes False as VSC1 no longer points to VS1.
• delete VS1. VSC1 will be deleted, however, it is bound to VS2 not VS1.

[xing-yang]

The fix is merged. Closing this.