chunks: close all opened MmapFiles on NewDirReader error path (#575)

Signed-off-by: Pavel Borzenkov <pavel.borzenkov@gmail.com>

CHANGELOG.md

@@ -3,6 +3,7 @@
  - [REMOVED] `FromData` is considered unused so was removed.
  - [FEATURE] Added option WALSegmentSize -1 to disable the WAL.
  - [BUGFIX] Fsync the meta file to persist it on disk to avoid data loss in case of a host crash.
+ - [BUGFIX] Fix fd and vm_area leak on error path in chunks.NewDirReader
 
 ## 0.6.1
   - [BUGFIX] Update `last` after appending a non-overlapping chunk in `chunks.MergeOverlappingChunks`. [#539](https://github.com/prometheus/tsdb/pull/539)

chunks/chunks.go

@@ -410,11 +410,14 @@ func NewDirReader(dir string, pool chunkenc.Pool) (*Reader, error) {
 	var (
 		bs   []ByteSlice
 		cs   []io.Closer
+		merr tsdb_errors.MultiError
 	)
 	for _, fn := range files {
 		f, err := fileutil.OpenMmapFile(fn)
 		if err != nil {
-			return nil, errors.Wrapf(err, "mmap files")
+			merr.Add(errors.Wrap(err, "mmap files"))
+			merr.Add(closeAll(cs))
+			return nil, merr
 		}
 		cs = append(cs, f)
 		bs = append(bs, realByteSlice(f.Bytes()))
@@ -422,7 +425,6 @@ func NewDirReader(dir string, pool chunkenc.Pool) (*Reader, error) {
 
 	reader, err := newReader(bs, cs, pool)
 	if err != nil {
-		var merr tsdb_errors.MultiError
 		merr.Add(err)
 		merr.Add(closeAll(cs))
 		return nil, merr