3 files changed, 20 insertions, 7 deletions
diff --git a/pkg/sentry/fs/flags.go b/pkg/sentry/fs/flags.go
index 1278f9c78..0fab876a9 100644
--- a/pkg/sentry/fs/flags.go
+++ b/pkg/sentry/fs/flags.go
@@ -28,7 +28,11 @@ type FileFlags struct {
 	// NonBlocking indicates that I/O should not block.
 	NonBlocking bool
 
-	// Sync indicates that any writes should be synchronous.
+	// DSync indicates that each write will flush data and metadata required to
+	// read the file's contents.
+	DSync bool
+
+	// Sync indicates that each write will flush data and all file metadata.
 	Sync bool
 
 	// Append indicates this file is append only.
@@ -96,6 +100,9 @@ func (f FileFlags) ToLinux() (mask uint) {
 	if f.NonBlocking {
 		mask |= linux.O_NONBLOCK
 	}
+	if f.DSync {
+		mask |= linux.O_DSYNC
+	}
 	if f.Sync {
 		mask |= linux.O_SYNC
 	}
diff --git a/pkg/sentry/fs/fs_state_autogen.go b/pkg/sentry/fs/fs_state_autogen.go
index 78505db1d..5ea2669e6 100755
--- a/pkg/sentry/fs/fs_state_autogen.go
+++ b/pkg/sentry/fs/fs_state_autogen.go
@@ -342,6 +342,7 @@ func (x *FileFlags) save(m state.Map) {
 	x.beforeSave()
 	m.Save("Direct", &x.Direct)
 	m.Save("NonBlocking", &x.NonBlocking)
+	m.Save("DSync", &x.DSync)
 	m.Save("Sync", &x.Sync)
 	m.Save("Append", &x.Append)
 	m.Save("Read", &x.Read)
@@ -358,6 +359,7 @@ func (x *FileFlags) afterLoad() {}
 func (x *FileFlags) load(m state.Map) {
 	m.Load("Direct", &x.Direct)
 	m.Load("NonBlocking", &x.NonBlocking)
+	m.Load("DSync", &x.DSync)
 	m.Load("Sync", &x.Sync)
 	m.Load("Append", &x.Append)
 	m.Load("Read", &x.Read)
diff --git a/pkg/sentry/fs/mount_overlay.go b/pkg/sentry/fs/mount_overlay.go
index 4fcdd6c01..299712cd7 100644
--- a/pkg/sentry/fs/mount_overlay.go
+++ b/pkg/sentry/fs/mount_overlay.go
@@ -66,13 +66,17 @@ func (o *overlayMountSourceOperations) Revalidate(ctx context.Context, name stri
 		panic("an overlay cannot revalidate file objects from the lower fs")
 	}
 
-	// Do we have anything to revalidate?
-	if child.overlay.upper == nil {
-		return false
+	var revalidate bool
+	child.overlay.copyMu.RLock()
+	if child.overlay.upper != nil {
+		// Does the upper require revalidation?
+		revalidate = o.upper.Revalidate(ctx, name, parent.overlay.upper, child.overlay.upper)
+	} else {
+		// Nothing to revalidate.
+		revalidate = false
 	}
-
-	// Does the upper require revalidation?
-	return o.upper.Revalidate(ctx, name, parent.overlay.upper, child.overlay.upper)
+	child.overlay.copyMu.RUnlock()
+	return revalidate
 }
 
 // Keep implements MountSourceOperations by delegating to the upper