From 68104d7cf321fff64346145b652647aeec10f70d Mon Sep 17 00:00:00 2001
From: Derek Collison <derek@nats.io>
Date: Wed, 9 Feb 2022 16:23:59 -0800
Subject: [PATCH] During a filestore snapshot we generate the fss files but
 were not cleaning them up if the block was deleted before a server restart.

https://gist.github.com/nekufa/010185dfb59261f222a0042d3a7d2a1c

Signed-off-by: Derek Collison <derek@nats.io>
---
 server/filestore.go   | 16 +++++++++++++-
 server/norace_test.go | 49 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/server/filestore.go b/server/filestore.go
index 055a8dea..04382869 100644
--- a/server/filestore.go
+++ b/server/filestore.go
@@ -30,6 +30,7 @@ import (
 	"net"
 	"os"
 	"path"
+	"path/filepath"
 	"runtime"
 	"sort"
 	"sync"
@@ -187,6 +188,8 @@ const (
 	indexScan = "%d.idx"
 	// used to load per subject meta information.
 	fssScan = "%d.fss"
+	// to look for orphans
+	fssScanAll = "*.fss"
 	// used to store our block encryption key.
 	keyScan = "%d.key"
 	// This is where we keep state on consumers.
@@ -890,7 +893,6 @@ func (fs *fileStore) recoverMsgs() error {
 						fs.psmc[subj] += ss.Msgs
 					}
 				}
-
 			} else {
 				return err
 			}
@@ -909,6 +911,14 @@ func (fs *fileStore) recoverMsgs() error {
 		return err
 	}
 
+	// We had a bug that would leave fss files around during a snapshot.
+	// Clean them up here if we see them.
+	if fms, err := filepath.Glob(path.Join(mdir, fssScanAll)); err == nil && len(fms) > 0 {
+		for _, fn := range fms {
+			os.Remove(fn)
+		}
+	}
+
 	// Limits checks and enforcement.
 	fs.enforceMsgLimit()
 	fs.enforceBytesLimit()
@@ -4326,6 +4336,10 @@ func (mb *msgBlock) dirtyCloseWithRemove(remove bool) {
 			os.Remove(mb.mfn)
 			mb.mfn = _EMPTY_
 		}
+		if mb.sfn != _EMPTY_ {
+			os.Remove(mb.sfn)
+			mb.sfn = _EMPTY_
+		}
 	}
 }
 
diff --git a/server/norace_test.go b/server/norace_test.go
index 968f582c..80164b76 100644
--- a/server/norace_test.go
+++ b/server/norace_test.go
@@ -29,6 +29,8 @@ import (
 	"net"
 	"net/http"
 	"net/url"
+	"path"
+	"path/filepath"
 	"runtime"
 	"runtime/debug"
 	"strconv"
@@ -4275,3 +4277,50 @@ func TestNoRaceJetStreamSparseConsumers(t *testing.T) {
 		})
 	}
 }
+
+func TestNoRaceFileStoreSubjectInfoWithSnapshotCleanup(t *testing.T) {
+	storeDir := createDir(t, JetStreamStoreDir)
+	defer removeDir(t, storeDir)
+
+	fs, err := newFileStore(FileStoreConfig{StoreDir: storeDir, BlockSize: 1024 * 1024}, StreamConfig{Name: "TEST", Storage: FileStorage})
+	require_NoError(t, err)
+	defer fs.Stop()
+
+	n, msg := 10_000, []byte(strings.Repeat("Z", 1024))
+	for i := 0; i < n; i++ {
+		_, _, err := fs.StoreMsg(fmt.Sprintf("X.%d", i), nil, msg)
+		require_NoError(t, err)
+	}
+
+	// Snapshot causes us to write out per subject info, fss files.
+	// We want to make sure they get cleaned up.
+	sr, err := fs.Snapshot(5*time.Second, false, false)
+	require_NoError(t, err)
+	var buf [4 * 1024 * 1024]byte
+	for {
+		if _, err = sr.Reader.Read(buf[:]); err == io.EOF {
+			break
+		}
+		require_NoError(t, err)
+	}
+
+	var seqs []uint64
+	for i := 1; i <= n; i++ {
+		seqs = append(seqs, uint64(i))
+	}
+	// Randomly delete msgs, make sure we cleanup as we empty the message blocks.
+	rand.Shuffle(len(seqs), func(i, j int) { seqs[i], seqs[j] = seqs[j], seqs[i] })
+
+	for _, seq := range seqs {
+		_, err := fs.RemoveMsg(seq)
+		require_NoError(t, err)
+	}
+
+	// We will have cleanup the main .blk and .idx sans the lmb, but we should not have any *.fss files.
+	fms, err := filepath.Glob(path.Join(storeDir, msgDir, fssScanAll))
+	require_NoError(t, err)
+
+	if len(fms) > 0 {
+		t.Fatalf("Expected to find no fss files, found %d", len(fms))
+	}
+}