hspace: change handling of N+1 bad clusters

Currently we just print a fake result and exit early. This is bad, since
it doesn't use the same codepaths for all the result printing, and has
already led to a bug where hspace looks like completely ignoring the
tiered specs request.

This patch changes the code to override the computation, instead of the
printout, thus allowing tiered specs results for such cases.

hspace.hs

@@ -296,11 +296,8 @@ main = do
   printKeys $ printStats PInitial ini_stats
 
   let bad_nodes = fst $ Cluster.computeBadItems nl il
-  when (length bad_nodes > 0) $ do
-         -- This is failn1 case, so we print the same final stats and
-         -- exit early
-         printResults nl num_instances 0 [(FailN1, 1)]
-         exitWith ExitSuccess
+      stop_allocation = length bad_nodes > 0
+      result_noalloc = ([(FailN1, 1)]::FailStats, nl, [])
 
   -- utility functions
   let iofspec spx = Instance.create "new" (rspecMem spx) (rspecDsk spx)
@@ -319,8 +316,10 @@ main = do
   (case optTieredSpec opts of
      Nothing -> return ()
      Just tspec -> do
-       let tresu = tieredAlloc nl il (iofspec tspec) req_nodes []
-       (_, trl_nl, trl_ixes) <- exitifbad tresu
+       (_, trl_nl, trl_ixes) <-
+           if stop_allocation
+           then return result_noalloc
+           else exitifbad (tieredAlloc nl il (iofspec tspec) req_nodes [])
        let fin_trl_ixes = reverse trl_ixes
            ix_byspec = groupBy ((==) `on` Instance.specOf) fin_trl_ixes
            spec_map = map (\ixs -> (Instance.specOf $ head ixs, length ixs))
@@ -347,8 +346,10 @@ main = do
 
   -- Run the standard (avg-mode) allocation
 
-  let result = iterateDepth nl il reqinst req_nodes []
-  (ereason, fin_nl, ixes) <- exitifbad result
+  (ereason, fin_nl, ixes) <-
+      if stop_allocation
+      then return result_noalloc
+      else exitifbad (iterateDepth nl il reqinst req_nodes [])
 
   let allocs = length ixes
       fin_ixes = reverse ixes