o/snapstate: put MaybeReboot edges on link-snap in AddLinkNewBaseOrKe…

…rnel and LinkNewBaseOrKernel

Sometimes during a remodel, we need to create link-snap tasks for snaps
that are already installed, but not yet considered boot participants.
These tasks were missing reboot boundaries, which caused the tasks to be
marked as done before the reboot completed.

tests/nested/manual/remodel-offline exhibits this behavior, where core22
already is installed, but not the model's base snap. The link-snap task
that was created during the remodel was being marked as done before the
reboot that the task triggers completed.

With this change, the entire remodel change will not be marked as done
until that link-snap task triggers is completed

overlord/snapstate/snapstate.go

@@ -3428,6 +3428,7 @@ func LinkNewBaseOrKernel(st *state.State, name string, fromChange string) (*stat
 	linkSnap.Set("snap-setup-task", prepareSnap.ID())
 	linkSnap.WaitFor(prev)
 	ts.AddTask(linkSnap)
+	ts.MarkEdge(linkSnap, MaybeRebootEdge)
 	// prepare-snap is the last task that carries no system modifications
 	ts.MarkEdge(prepareSnap, LastBeforeLocalModificationsEdge)
 	ts.MarkEdge(prepareSnap, SnapSetupEdge)
@@ -3490,6 +3491,7 @@ func AddLinkNewBaseOrKernel(st *state.State, ts *state.TaskSet) (*state.TaskSet,
 	linkSnap.Set("snap-setup-task", snapSetupTask.ID())
 	linkSnap.WaitFor(prev)
 	ts.AddTask(linkSnap)
+	ts.MarkEdge(linkSnap, MaybeRebootEdge)
 	// make sure that remodel can identify which tasks introduce actual
 	// changes to the system and order them correctly
 	if edgeTask := ts.MaybeEdge(LastBeforeLocalModificationsEdge); edgeTask == nil {

overlord/snapstate/snapstate_test.go

@@ -8162,6 +8162,7 @@ func (s *snapmgrTestSuite) testRemodelLinkNewBaseOrKernelHappy(c *C, model *asse
 	c.Assert(tLink.Kind(), Equals, "link-snap")
 	c.Assert(tLink.Summary(), Equals, `Make snap "some-kernel" (2) available to the system during remodel`)
 	c.Assert(tLink.WaitTasks(), DeepEquals, []*state.Task{tUpdateGadgetAssets})
+	c.Assert(ts.MaybeEdge(snapstate.MaybeRebootEdge), Equals, tLink)
 
 	ts, err = snapstate.LinkNewBaseOrKernel(s.state, "some-base", "")
 	c.Assert(err, IsNil)
@@ -8175,6 +8176,7 @@ func (s *snapmgrTestSuite) testRemodelLinkNewBaseOrKernelHappy(c *C, model *asse
 	c.Assert(tPrepare.Has("snap-setup"), Equals, true)
 	c.Assert(tLink.Kind(), Equals, "link-snap")
 	c.Assert(tLink.Summary(), Equals, `Make snap "some-base" (1) available to the system during remodel`)
+	c.Assert(ts.MaybeEdge(snapstate.MaybeRebootEdge), Equals, tLink)
 }
 
 func (s *snapmgrTestSuite) TestRemodelLinkNewBaseOrKernelBadType(c *C) {
@@ -8291,6 +8293,7 @@ func (s *snapmgrTestSuite) testRemodelAddLinkNewBaseOrKernel(c *C, model *assert
 		c.Assert(tsk.Get("snap-setup-task", &ssID), IsNil)
 		c.Assert(ssID, Equals, tPrepare.ID())
 	}
+	c.Assert(tsNew.MaybeEdge(snapstate.MaybeRebootEdge), Equals, tLink)
 
 	// try with base snap
 	si = &snap.SideInfo{RealName: "some-base", Revision: snap.R(1)}
@@ -8313,6 +8316,7 @@ func (s *snapmgrTestSuite) testRemodelAddLinkNewBaseOrKernel(c *C, model *assert
 	var ssID string
 	c.Assert(tLink.Get("snap-setup-task", &ssID), IsNil)
 	c.Assert(ssID, Equals, tPrepare.ID())
+	c.Assert(tsNew.MaybeEdge(snapstate.MaybeRebootEdge), Equals, tLink)
 
 	// but bails when there is no task with snap setup
 	ts = state.NewTaskSet()