fuse: forget fs.Node instances on request by the kernel

Forget fs.Node instances once the kernel frees the corresponding nodeId.
This ensures that restic does not run out of memory on large snapshots.

internal/fuse/fuse_test.go

@@ -119,7 +119,7 @@ func TestFuseFile(t *testing.T) {
 	root := &Root{repo: repo, blobCache: bloblru.New(blobCacheSize)}
 
 	inode := inodeFromNode(1, node)
-	f, err := newFile(root, inode, node)
+	f, err := newFile(root, func() {}, inode, node)
 	rtest.OK(t, err)
 	of, err := f.Open(context.TODO(), nil, nil)
 	rtest.OK(t, err)
@@ -162,7 +162,7 @@ func TestFuseDir(t *testing.T) {
 	}
 	parentInode := inodeFromName(0, "parent")
 	inode := inodeFromName(1, "foo")
-	d, err := newDir(root, inode, parentInode, node)
+	d, err := newDir(root, func() {}, inode, parentInode, node)
 	rtest.OK(t, err)
 
 	// don't open the directory as that would require setting up a proper tree blob
@@ -276,7 +276,7 @@ func TestLink(t *testing.T) {
 		{Name: "foo", Value: []byte("bar")},
 	}}
 
-	lnk, err := newLink(&Root{}, 42, node)
+	lnk, err := newLink(&Root{}, func() {}, 42, node)
 	rtest.OK(t, err)
 	target, err := lnk.Readlink(context.TODO(), nil)
 	rtest.OK(t, err)