update chunk log after speculated chunks are verified to be present

Only done in checkPresentChunks, although retrieveChunks could also do
it. Does not seem necessary though, because git-annex never retrives
content without first checking if it's present AFAICR. And really this will
only be needed when using fsck. Puttting it here, rather than in fsck
avoids breaking an abstraction boundary, and is nice and inexpensive.

Remote/Helper/Chunked.hs

@@ -206,7 +206,7 @@ seekResume h encryptor chunkkeys checker = do
  -}
 removeChunks :: Remover -> UUID -> ChunkConfig -> EncKey -> Key -> Annex ()
 removeChunks remover u chunkconfig encryptor k = do
-	ls <- chunkKeys u chunkconfig k
+	ls <- map chunkKeyList <$> chunkKeys u chunkconfig k
 	mapM_ (remover . encryptor) (concat ls)
 	let chunksizes = catMaybes $ map (fromKey keyChunkSize <=< headMaybe) ls
 	forM_ chunksizes $ chunksRemoved u k . FixedSizeChunks . fromIntegral
@@ -245,7 +245,8 @@ retrieveChunks retriever u chunkconfig encryptor basek dest basep sink
 			(\e -> go (Just e) =<< chunkKeysOnly u chunkconfig basek)
 	| otherwise = go Nothing =<< chunkKeys u chunkconfig basek
   where
-	go pe ls = do
+	go pe cks = do
+		let ls = map chunkKeyList cks
 		currsize <- liftIO $ catchMaybeIO $ getFileSize dest
 		let ls' = maybe ls (setupResume ls) currsize
 		if any null ls'
@@ -359,14 +360,18 @@ checkPresentChunks checker u chunkconfig encryptor basek
   where
 	checklists Nothing [] = return False
 	checklists (Just deferrederror) [] = throwM deferrederror
-	checklists d (l:ls)
+	checklists d (ck:cks)
 		| not (null l) = do
 			v <- checkchunks l
 			case v of
-				Left e -> checklists (Just e) ls
-				Right True -> return True
-				Right False -> checklists Nothing ls
-		| otherwise = checklists d ls
+				Left e -> checklists (Just e) cks
+				Right True -> do
+					ensureChunksAreLogged u basek ck
+					return True
+				Right False -> checklists Nothing cks
+		| otherwise = checklists d cks
+	  where
+		l = chunkKeyList ck
 	
 	checkchunks :: [Key] -> Annex (Either SomeException Bool)
 	checkchunks [] = return (Right True)
@@ -379,6 +384,14 @@ checkPresentChunks checker u chunkconfig encryptor basek
 
 	check = tryNonAsync . checker . encryptor
 
+data ChunkKeys
+	= ChunkKeys [Key]
+	| SpeculativeChunkKeys (ChunkMethod, ChunkCount) [Key]
+
+chunkKeyList :: ChunkKeys -> [Key]
+chunkKeyList (ChunkKeys l) = l
+chunkKeyList (SpeculativeChunkKeys _ l) = l
+
 {- A key can be stored in a remote unchunked, or as a list of chunked keys.
  - This can be the case whether or not the remote is currently configured
  - to use chunking.
@@ -395,22 +408,22 @@ checkPresentChunks checker u chunkconfig encryptor basek
  - recover from data loss, where the chunk log didn't make it out,
  - though only as long as the ChunkConfig is unchanged.
  -}
-chunkKeys :: UUID -> ChunkConfig -> Key -> Annex [[Key]]
+chunkKeys :: UUID -> ChunkConfig -> Key -> Annex [ChunkKeys]
 chunkKeys = chunkKeys' False
 
 {- Same as chunkKeys, but excluding the unchunked key. -}
-chunkKeysOnly :: UUID -> ChunkConfig -> Key -> Annex [[Key]]
+chunkKeysOnly :: UUID -> ChunkConfig -> Key -> Annex [ChunkKeys]
 chunkKeysOnly = chunkKeys' True
 
-chunkKeys' :: Bool -> UUID -> ChunkConfig -> Key -> Annex [[Key]]
+chunkKeys' :: Bool -> UUID -> ChunkConfig -> Key -> Annex [ChunkKeys]
 chunkKeys' onlychunks u chunkconfig k = do
 	recorded <- getCurrentChunks u k
-	let recordedl  = map (toChunkList k) recorded
+	let recordedl = map (ChunkKeys . toChunkList k) recorded
 	return $ addspeculative recorded $ if onlychunks
 		then recordedl
 		else if noChunks chunkconfig
-			then [k] : recordedl
-			else recordedl ++ [[k]]
+			then ChunkKeys [k] : recordedl
+			else recordedl ++ [ChunkKeys [k]]
   where
 	addspeculative recorded l = case chunkconfig of
 		NoChunks -> l
@@ -422,10 +435,19 @@ chunkKeys' onlychunks u chunkconfig k = do
  				    v = (FixedSizeChunks chunksz, chunkcount)
 				in if v `elem` recorded
 					then l
-					else l ++ [toChunkList k v]
+					else l ++ [SpeculativeChunkKeys v (toChunkList k v)]
 		LegacyChunks _ -> l
 
 toChunkList :: Key -> (ChunkMethod, ChunkCount) -> [Key]
 toChunkList k (FixedSizeChunks chunksize, chunkcount) =
 	takeChunkKeyStream chunkcount $ chunkKeyStream k chunksize
 toChunkList _ (UnknownChunks _, _) = []
+
+{- When chunkKeys provided a speculative chunk list, and that has been
+ - verified to be present, use this to log it in the chunk log. This way,
+ - a later change to the chunk size of the remote won't prevent accessing
+ - the chunks. -}
+ensureChunksAreLogged :: UUID -> Key -> ChunkKeys -> Annex ()
+ensureChunksAreLogged u k (SpeculativeChunkKeys (chunkmethod, chunkcount) _) = 
+	chunksStored u k chunkmethod chunkcount
+ensureChunksAreLogged _ _ (ChunkKeys _) = return ()

doc/bugs/fsck_--key_without___34__chunking__34___information_in_git-annex_does_not_try_chunks.mdwn

@@ -24,3 +24,5 @@ but `annex fsck --key KEY --from remote --fast`, since it doesn't have an exact
 
 [[!meta author=yoh]]
 [[!tag projects/dandi]]
+
+> [[done]] --[[Joey]]