backport of commit b1657dd

.changelog/20550.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+csi: Fixed a bug where concurrent mount and unmount operations could unstage volumes needed by another allocation
+```

client/pluginmanager/csimanager/volume.go

@@ -253,6 +253,10 @@ func (v *volumeManager) MountVolume(ctx context.Context, vol *structs.CSIVolume,
 	logger := v.logger.With("volume_id", vol.ID, "alloc_id", alloc.ID)
 	ctx = hclog.WithContext(ctx, logger)
 
+	// Claim before we stage/publish to prevent interleaved Unmount for another
+	// alloc from unstaging between stage/publish steps below
+	v.usageTracker.Claim(alloc.ID, vol.ID, vol.Namespace, usage)
+
 	if v.requiresStaging {
 		err = v.stageVolume(ctx, vol, usage, publishContext)
 	}
@@ -261,10 +265,6 @@ func (v *volumeManager) MountVolume(ctx context.Context, vol *structs.CSIVolume,
 		mountInfo, err = v.publishVolume(ctx, vol, alloc, usage, publishContext)
 	}
 
-	if err == nil {
-		v.usageTracker.Claim(alloc.ID, vol.ID, vol.Namespace, usage)
-	}
-
 	event := structs.NewNodeEvent().
 		SetSubsystem(structs.NodeEventSubsystemStorage).
 		SetMessage("Mount volume").
@@ -274,6 +274,7 @@ func (v *volumeManager) MountVolume(ctx context.Context, vol *structs.CSIVolume,
 	} else {
 		event.AddDetail("success", "false")
 		event.AddDetail("error", err.Error())
+		v.usageTracker.Free(alloc.ID, vol.ID, vol.Namespace, usage)
 	}
 
 	v.eventer(event)

client/pluginmanager/csimanager/volume_test.go

@@ -9,14 +9,17 @@ import (
 	"os"
 	"runtime"
 	"testing"
+	"time"
 
+	"github.com/hashicorp/go-hclog"
 	"github.com/hashicorp/nomad/ci"
 	"github.com/hashicorp/nomad/helper/mount"
 	"github.com/hashicorp/nomad/helper/testlog"
 	"github.com/hashicorp/nomad/nomad/mock"
 	"github.com/hashicorp/nomad/nomad/structs"
 	"github.com/hashicorp/nomad/plugins/csi"
 	csifake "github.com/hashicorp/nomad/plugins/csi/fake"
+	"github.com/shoenig/test/must"
 	"github.com/stretchr/testify/require"
 )
 
@@ -526,3 +529,71 @@ func TestVolumeManager_MountVolumeEvents(t *testing.T) {
 	require.Equal(t, "vol", e.Details["volume_id"])
 	require.Equal(t, "true", e.Details["success"])
 }
+
+// TestVolumeManager_InterleavedStaging tests that a volume cannot be unstaged
+// if another alloc has staged but not yet published
+func TestVolumeManager_InterleavedStaging(t *testing.T) {
+	ci.Parallel(t)
+
+	tmpPath := t.TempDir()
+	csiFake := &csifake.Client{}
+
+	logger := testlog.HCLogger(t)
+	ctx := hclog.WithContext(context.Background(), logger)
+
+	manager := newVolumeManager(logger,
+		func(e *structs.NodeEvent) {}, csiFake,
+		tmpPath, tmpPath, true, "i-example")
+
+	alloc0, alloc1 := mock.Alloc(), mock.Alloc()
+	vol := &structs.CSIVolume{ID: "vol", Namespace: "ns"}
+	usage := &UsageOptions{
+		AccessMode:     structs.CSIVolumeAccessModeMultiNodeMultiWriter,
+		AttachmentMode: structs.CSIVolumeAttachmentModeFilesystem,
+	}
+	pubCtx := map[string]string{}
+
+	// first alloc has previously claimed the volume
+	manager.usageTracker.Claim(alloc0.ID, vol.ID, vol.Namespace, usage)
+
+	alloc0WaitCh := make(chan struct{})
+	alloc1WaitCh := make(chan struct{})
+
+	// this goroutine simulates MountVolume, but with control over interleaving
+	// by waiting for the other alloc to check if should unstage before trying
+	// to publish
+	manager.usageTracker.Claim(alloc1.ID, vol.ID, vol.Namespace, usage)
+	must.NoError(t, manager.stageVolume(ctx, vol, usage, pubCtx))
+
+	go func() {
+		defer close(alloc1WaitCh)
+		<-alloc0WaitCh
+		_, err := manager.publishVolume(ctx, vol, alloc1, usage, pubCtx)
+		must.NoError(t, err)
+	}()
+
+	must.NoError(t, manager.UnmountVolume(ctx, vol.Namespace, vol.ID, "foo", alloc0.ID, usage))
+	close(alloc0WaitCh)
+
+	testTimeoutCtx, cancel := context.WithTimeout(context.TODO(), time.Second)
+	t.Cleanup(cancel)
+
+	select {
+	case <-alloc1WaitCh:
+	case <-testTimeoutCtx.Done():
+		t.Fatal("test timed out")
+	}
+
+	key := volumeUsageKey{
+		id:        vol.ID,
+		ns:        vol.Namespace,
+		usageOpts: *usage,
+	}
+
+	manager.usageTracker.stateMu.Lock()
+	t.Cleanup(manager.usageTracker.stateMu.Unlock)
+	must.Eq(t, []string{alloc1.ID}, manager.usageTracker.state[key])
+
+	must.Eq(t, 1, csiFake.NodeUnpublishVolumeCallCount, must.Sprint("expected 1 unpublish call"))
+	must.Eq(t, 0, csiFake.NodeUnstageVolumeCallCount, must.Sprint("expected no unstage call"))
+}