fuse: support handleless read/write that skips the OPEN opcode.

fuse/nodefs/fileless_test.go

@@ -9,14 +9,22 @@ import (
 
 type nodeReadNode struct {
 	Node
+	noOpen bool
 	data   []byte
 }
 
-func newNodeReadNode(d []byte) *nodeReadNode {
-	return &nodeReadNode{NewDefaultNode(), d}
+func newNodeReadNode(noOpen bool, d []byte) *nodeReadNode {
+	return &nodeReadNode{
+		Node:   NewDefaultNode(),
+		noOpen: noOpen,
+		data:   d,
+	}
 }
 
 func (n *nodeReadNode) Open(flags uint32, context *fuse.Context) (file File, code fuse.Status) {
+	if n.noOpen {
+		return nil, fuse.ENOSYS
+	}
 	return nil, fuse.OK
 }
 
@@ -31,17 +39,53 @@ func (n *nodeReadNode) Read(file File, dest []byte, off int64, context *fuse.Con
 func (n *nodeReadNode) Lookup(out *fuse.Attr, name string, context *fuse.Context) (*Inode, fuse.Status) {
 	out.Mode = fuse.S_IFREG | 0644
 	out.Size = uint64(len(name))
-	ch := n.Inode().NewChild(name, false, newNodeReadNode([]byte(name)))
+	ch := n.Inode().NewChild(name, false, newNodeReadNode(n.noOpen, []byte(name)))
 	return ch, fuse.OK
 }
 
+func TestNoOpen(t *testing.T) {
+	dir, err := ioutil.TempDir("", "nodefs")
+	if err != nil {
+		t.Fatalf("TempDir: %v", err)
+	}
+
+	root := newNodeReadNode(true, nil)
+	root.noOpen = true
+
+	s, _, err := MountRoot(dir, root, nil)
+	if err != nil {
+		t.Fatalf("MountRoot: %v", err)
+	}
+	s.SetDebug(VerboseTest())
+	defer s.Unmount()
+	go s.Serve()
+	content, err := ioutil.ReadFile(dir + "/file")
+	if err != nil {
+		t.Fatalf("ReadFile: %v", err)
+	}
+	want := "file"
+	if string(content) != want {
+		t.Fatalf("got %q, want %q", content, want)
+	}
+
+	content, err = ioutil.ReadFile(dir + "/file2")
+	if err != nil {
+		t.Fatalf("ReadFile: %v", err)
+	}
+
+	want = "file2"
+	if string(content) != want {
+		t.Fatalf("got %q, want %q", content, want)
+	}
+}
+
 func TestNodeRead(t *testing.T) {
 	dir, err := ioutil.TempDir("", "nodefs")
 	if err != nil {
 		t.Fatalf("TempDir: %v", err)
 	}
 
-	root := newNodeReadNode(nil)
+	root := newNodeReadNode(false, nil)
 	s, _, err := MountRoot(dir, root, nil)
 	if err != nil {
 		t.Fatalf("MountRoot: %v", err)
@@ -56,4 +100,5 @@ func TestNodeRead(t *testing.T) {
 	if string(content) != want {
 		t.Fatalf("got %q, want %q", content, want)
 	}
+
 }

fuse/opcode.go

@@ -79,7 +79,7 @@ func doInit(server *Server, req *request) {
 	server.reqMu.Lock()
 	server.kernelSettings = *input
 	server.kernelSettings.Flags = input.Flags & (CAP_ASYNC_READ | CAP_BIG_WRITES | CAP_FILE_OPS |
-		CAP_AUTO_INVAL_DATA | CAP_READDIRPLUS)
+		CAP_AUTO_INVAL_DATA | CAP_READDIRPLUS | CAP_NO_OPEN_SUPPORT)
 
 	if input.Minor >= 13 {
 		server.setSplice()

fuse/print.go

@@ -39,9 +39,9 @@ func init() {
 		CAP_AUTO_INVAL_DATA:  "AUTO_INVAL_DATA",
 		CAP_READDIRPLUS:      "READDIRPLUS",
 		CAP_READDIRPLUS_AUTO: "READDIRPLUS_AUTO",
-		CAP_FUSE_ASYNC_DIO:       "ASYNC_DIO",
-		CAP_FUSE_WRITEBACK_CACHE: "WRITEBACK_CACHE",
-		CAP_FUSE_NO_OPEN_SUPPORT: "NO_OPEN_SUPPORT",
+		CAP_ASYNC_DIO:        "ASYNC_DIO",
+		CAP_WRITEBACK_CACHE:  "WRITEBACK_CACHE",
+		CAP_NO_OPEN_SUPPORT:  "NO_OPEN_SUPPORT",
 	}
 	releaseFlagNames = map[int64]string{
 		RELEASE_FLUSH: "FLUSH",

fuse/request_linux.go

@@ -5,5 +5,5 @@ const outputHeaderSize = 160
 const (
 	_FUSE_KERNEL_VERSION   = 7
 	_MINIMUM_MINOR_VERSION = 12
-	_OUR_MINOR_VERSION     = 21
+	_OUR_MINOR_VERSION     = 23
 )

fuse/types.go

@@ -158,9 +158,9 @@ const (
 	CAP_AUTO_INVAL_DATA  = (1 << 12)
 	CAP_READDIRPLUS      = (1 << 13)
 	CAP_READDIRPLUS_AUTO = (1 << 14)
-	CAP_FUSE_ASYNC_DIO       = (1 << 15)
-	CAP_FUSE_WRITEBACK_CACHE = (1 << 16)
-	CAP_FUSE_NO_OPEN_SUPPORT = (1 << 17)
+	CAP_ASYNC_DIO        = (1 << 15)
+	CAP_WRITEBACK_CACHE  = (1 << 16)
+	CAP_NO_OPEN_SUPPORT  = (1 << 17)
 )
 
 type InitIn struct {