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, 15 insertions, 14 deletions

diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go
index 94d96261b..baecb88c4 100644
--- a/pkg/sentry/fsimpl/gofer/filesystem.go
+++ b/pkg/sentry/fsimpl/gofer/filesystem.go
@@ -35,7 +35,7 @@ import (
 
 // Sync implements vfs.FilesystemImpl.Sync.
 func (fs *filesystem) Sync(ctx context.Context) error {
-	// Snapshot current syncable dentries and special files.
+	// Snapshot current syncable dentries and special file FDs.
 	fs.syncMu.Lock()
 	ds := make([]*dentry, 0, len(fs.syncableDentries))
 	for d := range fs.syncableDentries {
@@ -53,22 +53,28 @@ func (fs *filesystem) Sync(ctx context.Context) error {
 	// regardless.
 	var retErr error
 
-	// Sync regular files.
+	// Sync syncable dentries.
 	for _, d := range ds {
-		err := d.syncCachedFile(ctx)
+		err := d.syncCachedFile(ctx, true /* forFilesystemSync */)
 		d.DecRef(ctx)
-		if err != nil && retErr == nil {
-			retErr = err
+		if err != nil {
+			ctx.Infof("gofer.filesystem.Sync: dentry.syncCachedFile failed: %v", err)
+			if retErr == nil {
+				retErr = err
+			}
 		}
 	}
 
 	// Sync special files, which may be writable but do not use dentry shared
 	// handles (so they won't be synced by the above).
 	for _, sffd := range sffds {
-		err := sffd.Sync(ctx)
+		err := sffd.sync(ctx, true /* forFilesystemSync */)
 		sffd.vfsfd.DecRef(ctx)
-		if err != nil && retErr == nil {
-			retErr = err
+		if err != nil {
+			ctx.Infof("gofer.filesystem.Sync: specialFileFD.sync failed: %v", err)
+			if retErr == nil {
+				retErr = err
+			}
 		}
 	}
 
@@ -229,7 +235,7 @@ func (fs *filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.Vir
 		return nil, err
 	}
 	if child != nil {
-		if !file.isNil() && inoFromPath(qid.Path) == child.ino {
+		if !file.isNil() && qid.Path == child.qidPath {
 			// The file at this path hasn't changed. Just update cached metadata.
 			file.close(ctx)
 			child.updateFromP9AttrsLocked(attrMask, &attr)
@@ -1512,7 +1518,6 @@ func (fs *filesystem) BoundEndpointAt(ctx context.Context, rp *vfs.ResolvingPath
 			d.IncRef()
 			return &endpoint{
 				dentry: d,
-				file:   d.file.file,
 				path:   opts.Addr,
 			}, nil
 		}
@@ -1591,7 +1596,3 @@ func (fs *filesystem) PrependPath(ctx context.Context, vfsroot, vd vfs.VirtualDe
 	defer fs.renameMu.RUnlock()
 	return genericPrependPath(vfsroot, vd.Mount(), vd.Dentry().Impl().(*dentry), b)
 }
-
-func (fs *filesystem) nextSyntheticIno() inodeNumber {
-	return inodeNumber(atomic.AddUint64(&fs.syntheticSeq, 1) | syntheticInoMask)
-}