fix handling of tenative cursor presence if protection strategy doesn't use it (#714)

Before this PR, we would panic in the `check` phase of `endpoint.Send()`'s `TryBatchDestroy` call in the following cases: the current protection strategy does NOT produce a tentative replication cursor AND
  * `FromVersion` is a tentative cursor bookmark
  * `FromVersion` is a snapshot, and there exists a tentative cursor bookmark for that snapshot
  * `FromVersion` is a bookmark != tentative cursor bookmark, but there exists a tentative cursor bookmark for the same snapshot as the `FromVersion` bookmark

In those cases, the `check` concluded that we would delete `FromVersion`.
It came to that conclusion because the tentative cursor isn't part of `obsoleteAbs` if the protection strategy doesn't produce a tentative replication cursor.

The scenarios above can happen if the user changes the protection strategy from "with tentative cursor" to one "without tentative replication cursor", while there is a tentative replication cursor on disk.
The workaround was to rename the tentative cursor.

In all cases above, `TryBatchDestroy` would have destroyed the tentative cursor.

In case 1, that would fail the `Send` step and potentially break replication if the cursor is the last common bookmark. The `check` conclusion was correct.

In cases 2 and 3, deleting the tentative cursor would have been fine because `FromVersion` was a different entity than the tentative cursor. So, destroying the tentative cursor would be the right call.

The solution in this PR is as follows:
* add the `FromVersion` to the `liveAbs` set of live abstractions
* rewrite the `check` closure to use the full dataset path (`fullpath`) to identify the concrete ZFS object instead of the `zfs.FilesystemVersionEqualIdentity`, which is only identified by matching GUID.
  * Holds have no dataset path and are not the `FromVersion` in any case, so disregard them.

fixes #666

This commit is contained in:

Christian Schwarz

2023-07-04 20:21:48 +02:00

committed by

GitHub

parent bc5e1ede04

commit bbdc6f5465

5 changed files with 200 additions and 29 deletions

									
										platformtest/tests/generated_cases.go
									
		+1
		
												View File
												
				@@ -20,6 +20,7 @@ var Cases = []Case{BatchDestroy,

					ReplicationIncrementalCleansUpStaleAbstractionsWithCacheOnSecondReplication,

					ReplicationIncrementalCleansUpStaleAbstractionsWithoutCacheOnSecondReplication,

					ReplicationIncrementalDestroysStepHoldsIffIncrementalStepHoldsAreDisabledButStepHoldsExist,

					ReplicationIncrementalHandlesFromVersionEqTentativeCursorCorrectly,

					ReplicationIncrementalIsPossibleIfCommonSnapshotIsDestroyed,

					ReplicationInitialAll,

					ReplicationInitialFail,