Support VFS2 save/restore.

Inode number consistency checks are now skipped in save/restore tests for
reasons described in greatest detail in StatTest.StateDoesntChangeAfterRename.
They pass in VFS1 due to the bug described in new test case
SimpleStatTest.DifferentFilesHaveDifferentDeviceInodeNumberPairs.

Fixes #1663

PiperOrigin-RevId: 338776148

1 files changed, 14 insertions, 10 deletions

diff --git a/pkg/sentry/vfs/vfs.go b/pkg/sentry/vfs/vfs.go
index 38d2701d2..48d6252f7 100644
--- a/pkg/sentry/vfs/vfs.go
+++ b/pkg/sentry/vfs/vfs.go
@@ -71,7 +71,7 @@ type VirtualFilesystem struct {
 	// points.
 	//
 	// mounts is analogous to Linux's mount_hashtable.
-	mounts mountTable
+	mounts mountTable `state:".([]*Mount)"`
 
 	// mountpoints maps mount points to mounts at those points in all
 	// namespaces. mountpoints is protected by mountMu.
@@ -780,23 +780,27 @@ func (vfs *VirtualFilesystem) RemoveXattrAt(ctx context.Context, creds *auth.Cre
 
 // SyncAllFilesystems has the semantics of Linux's sync(2).
 func (vfs *VirtualFilesystem) SyncAllFilesystems(ctx context.Context) error {
+	var retErr error
+	for fs := range vfs.getFilesystems() {
+		if err := fs.impl.Sync(ctx); err != nil && retErr == nil {
+			retErr = err
+		}
+		fs.DecRef(ctx)
+	}
+	return retErr
+}
+
+func (vfs *VirtualFilesystem) getFilesystems() map[*Filesystem]struct{} {
 	fss := make(map[*Filesystem]struct{})
 	vfs.filesystemsMu.Lock()
+	defer vfs.filesystemsMu.Unlock()
 	for fs := range vfs.filesystems {
 		if !fs.TryIncRef() {
 			continue
 		}
 		fss[fs] = struct{}{}
 	}
-	vfs.filesystemsMu.Unlock()
-	var retErr error
-	for fs := range fss {
-		if err := fs.impl.Sync(ctx); err != nil && retErr == nil {
-			retErr = err
-		}
-		fs.DecRef(ctx)
-	}
-	return retErr
+	return fss
 }
 
 // MkdirAllAt recursively creates non-existent directories on the given path