refactor multi errors

Signed-off-by: Krasi Georgiev <kgeorgie@redhat.com>

block.go

@@ -277,9 +277,10 @@ func OpenBlock(logger log.Logger, dir string, pool chunkenc.Pool) (pb *Block, er
 	var closers []io.Closer
 	defer func() {
 		if err != nil {
-			for _, c := range closers {
-				c.Close()
-			}
+			var merr MultiError
+			merr.Add(err)
+			merr.Add(closeAll(closers))
+			err = merr.Err()
 		}
 	}()
 	meta, err := readMetaFile(dir)

chunks/chunks.go

@@ -342,7 +342,7 @@ func NewDirReader(dir string, pool chunkenc.Pool) (*Reader, error) {
 }
 
 func (s *Reader) Close() error {
-	return closeAll(s.cs...)
+	return closeAll(s.cs)
 }
 
 // Size returns the size of the chunks.
@@ -410,7 +410,7 @@ func sequenceFiles(dir string) ([]string, error) {
 	return res, nil
 }
 
-func closeAll(cs ...io.Closer) (err error) {
+func closeAll(cs []io.Closer) (err error) {
 	for _, c := range cs {
 		if e := c.Close(); e != nil {
 			err = e

compact.go

@@ -582,7 +582,7 @@ func (c *LeveledCompactor) write(dest string, meta *BlockMeta, blocks ...BlockRe
 
 // populateBlock fills the index and chunk writers with new data gathered as the union
 // of the provided blocks. It returns meta information for the new block.
-func (c *LeveledCompactor) populateBlock(blocks []BlockReader, meta *BlockMeta, indexw IndexWriter, chunkw ChunkWriter) error {
+func (c *LeveledCompactor) populateBlock(blocks []BlockReader, meta *BlockMeta, indexw IndexWriter, chunkw ChunkWriter) (err error) {
 	if len(blocks) == 0 {
 		return errors.New("cannot populate block from no readers")
 	}
@@ -592,7 +592,12 @@ func (c *LeveledCompactor) populateBlock(blocks []BlockReader, meta *BlockMeta,
 		allSymbols = make(map[string]struct{}, 1<<16)
 		closers    = []io.Closer{}
 	)
-	defer func() { closeAll(closers...) }()
+	defer func() {
+		var merr MultiError
+		merr.Add(err)
+		merr.Add(closeAll(closers))
+		err = merr.Err()
+	}()
 
 	for i, b := range blocks {
 		indexr, err := b.Index()

db.go

@@ -1097,7 +1097,7 @@ func (es MultiError) Err() error {
 	return es
 }
 
-func closeAll(cs ...io.Closer) error {
+func closeAll(cs []io.Closer) error {
 	var merr MultiError
 
 	for _, c := range cs {