Introduce new interfaces:

* NodeFileSystem: interface for defining filesystems in terms of inodes.

* FsNode: interface for inodes to be used by NodeFileSystem

* PathNodeFs: NodeFileSystem that assumes bijective mapping between
  inodes and paths

* Change inode to Inode, a public (but mostly opaque) type.

fuse/Makefile

@@ -12,7 +12,6 @@ MANUAL_GOFILES=api.go \
 	direntry.go\
 	files.go \
 	fsmount.go \
-	fsinode.go \
 	fsconnector.go \
 	fuse.go \
 	handle.go \
@@ -25,6 +24,7 @@ MANUAL_GOFILES=api.go \
 	mount.go \
 	mountstate.go \
 	opcode.go \
+	pathfs.go \
 	pathdebug.go \
 	fsops.go \
 	readonlyfs.go \

fuse/api.go

@@ -8,7 +8,7 @@ import (
 
 // Types for users to implement.
 
-type InodeFs interface {
+type NodeFileSystem interface {
 	Unmount()
 	Mount(conn *FileSystemConnector)
 	StatFs() *StatfsOut
@@ -17,8 +17,9 @@ type InodeFs interface {
 
 type FsNode interface {
 	// The following are called by the FileSystemConnector
-	Inode() *inode
-	SetInode(node *inode)
+	Inode() *Inode
+	SetInode(node *Inode)
+	
 	RmChild(name string, child FsNode)
 	AddChild(name string, child FsNode)
 
@@ -137,6 +138,7 @@ type File interface {
 	Fsync(*FsyncIn) (code Status)
 }
 
+// Wrap a File return in this to set FUSE flags.
 type WithFlags struct {
 	File
 

fuse/fsconnector.go

@@ -32,7 +32,7 @@ type FileSystemConnector struct {
 
 	fsInit   RawFsInit
 	inodeMap HandleMap
-	rootNode *inode
+	rootNode *Inode
 }
 
 func NewFileSystemConnector(fs FileSystem, opts *FileSystemOptions) (me *FileSystemConnector) {
@@ -56,17 +56,17 @@ func (me *FileSystemConnector) verify() {
 	root.verify(me.rootNode.mountPoint)
 }
 
-func (me *FileSystemConnector) newInode(isDir bool) *inode {
-	data := new(inode)
+func (me *FileSystemConnector) newInode(isDir bool) *Inode {
+	data := new(Inode)
 	data.nodeId = me.inodeMap.Register(&data.handled)
 	if isDir {
-		data.children = make(map[string]*inode, initDirSize)
+		data.children = make(map[string]*Inode, initDirSize)
 	}
 
 	return data
 }
 
-func (me *FileSystemConnector) lookupUpdate(parent *inode, name string, isDir bool, lookupCount int) *inode {
+func (me *FileSystemConnector) lookupUpdate(parent *Inode, name string, isDir bool, lookupCount int) *Inode {
 	defer me.verify()
 
 	parent.treeLock.Lock()
@@ -83,7 +83,7 @@ func (me *FileSystemConnector) lookupUpdate(parent *inode, name string, isDir bo
 	return data
 }
 
-func (me *FileSystemConnector) lookupMount(parent *inode, name string, lookupCount int) (mount *fileSystemMount) {
+func (me *FileSystemConnector) lookupMount(parent *Inode, name string, lookupCount int) (mount *fileSystemMount) {
 	parent.treeLock.RLock()
 	defer parent.treeLock.RUnlock()
 	if parent.mounts == nil {
@@ -100,11 +100,11 @@ func (me *FileSystemConnector) lookupMount(parent *inode, name string, lookupCou
 	return nil
 }
 
-func (me *FileSystemConnector) getInodeData(nodeid uint64) *inode {
+func (me *FileSystemConnector) getInodeData(nodeid uint64) *Inode {
 	if nodeid == FUSE_ROOT_ID {
 		return me.rootNode
 	}
-	return (*inode)(unsafe.Pointer(DecodeHandle(nodeid)))
+	return (*Inode)(unsafe.Pointer(DecodeHandle(nodeid)))
 }
 
 func (me *FileSystemConnector) forgetUpdate(nodeId uint64, forgetCount int) {
@@ -119,7 +119,7 @@ func (me *FileSystemConnector) forgetUpdate(nodeId uint64, forgetCount int) {
 	me.considerDropInode(node)
 }
 
-func (me *FileSystemConnector) considerDropInode(n *inode) (drop bool) {
+func (me *FileSystemConnector) considerDropInode(n *Inode) (drop bool) {
 	delChildren := []string{}
 	for k, v := range n.children {
 		if v.mountPoint == nil && me.considerDropInode(v) {
@@ -146,7 +146,7 @@ func (me *FileSystemConnector) considerDropInode(n *inode) (drop bool) {
 	return len(n.openFiles) == 0 
 }
 
-func (me *FileSystemConnector) renameUpdate(oldParent *inode, oldName string, newParent *inode, newName string) {
+func (me *FileSystemConnector) renameUpdate(oldParent *Inode, oldName string, newParent *Inode, newName string) {
 	defer me.verify()
 	oldParent.treeLock.Lock()
 	defer oldParent.treeLock.Unlock()
@@ -163,7 +163,7 @@ func (me *FileSystemConnector) renameUpdate(oldParent *inode, oldName string, ne
 	newParent.addChild(newName, node)
 }
 
-func (me *FileSystemConnector) unlinkUpdate(parent *inode, name string) {
+func (me *FileSystemConnector) unlinkUpdate(parent *Inode, name string) {
 	defer me.verify()
 	
 	parent.treeLock.Lock()
@@ -174,7 +174,7 @@ func (me *FileSystemConnector) unlinkUpdate(parent *inode, name string) {
 
 // Walk the file system starting from the root. Will return nil if
 // node not found.
-func (me *FileSystemConnector) findLastKnownInode(fullPath string) (*inode, []string) {
+func (me *FileSystemConnector) findLastKnownInode(fullPath string) (*Inode, []string) {
 	if fullPath == "" {
 		return me.rootNode, nil
 	}
@@ -203,7 +203,7 @@ func (me *FileSystemConnector) findLastKnownInode(fullPath string) (*inode, []st
 	return node, nil
 }
 
-func (me *FileSystemConnector) findInode(fullPath string) *inode {
+func (me *FileSystemConnector) findInode(fullPath string) *Inode {
 	n, rest := me.findLastKnownInode(fullPath)
 	if len(rest) > 0 {
 		return nil
@@ -217,7 +217,7 @@ func (me *FileSystemConnector) findInode(fullPath string) *inode {
 // system there.  If opts is nil, the mount options of the root file
 // system are inherited.  The encompassing filesystem should pretend
 // the mount point does not exist.  If it does, it will generate an
-// inode with the same, which will cause Mount() to return EBUSY.
+// Inode with the same, which will cause Mount() to return EBUSY.
 //
 // Return values:
 //
@@ -257,8 +257,8 @@ func (me *FileSystemConnector) Mount(mountPoint string, fs FileSystem, opts *Fil
 		opts = me.rootNode.mountPoint.options
 	}
 
-	ifs := newInodeFs(fs)
-	node.mountFs(ifs, opts)
+	nodeFs := NewPathNodeFs(fs)
+	node.mountFs(nodeFs, opts)
 	parent.addChild(base, node)
 
 	if parent.mounts == nil {
@@ -275,7 +275,7 @@ func (me *FileSystemConnector) Mount(mountPoint string, fs FileSystem, opts *Fil
 }
 
 func (me *FileSystemConnector) mountRoot(fs FileSystem, opts *FileSystemOptions) {
-	ifs := newInodeFs(fs)
+	ifs := NewPathNodeFs(fs)
 	me.rootNode.mountFs(ifs, opts)
 	ifs.Mount(me)
 	me.verify()

fuse/fsmount.go

@@ -24,10 +24,10 @@ type openedFile struct {
 
 type fileSystemMount struct {
 	// The file system we mounted here.
-	fs InodeFs
+	fs NodeFileSystem
 
 	// Node that we were mounted on.
-	mountInode *inode
+	mountInode *Inode
 
 	// Options for the mount.
 	options *FileSystemOptions
@@ -69,7 +69,7 @@ func (me *FileSystemConnector) getOpenedFile(h uint64) *openedFile {
 	return b
 }
 
-func (me *fileSystemMount) unregisterFileHandle(handle uint64, node *inode) *openedFile {
+func (me *fileSystemMount) unregisterFileHandle(handle uint64, node *Inode) *openedFile {
 	obj := me.openFiles.Forget(handle)
 	opened := (*openedFile)(unsafe.Pointer(obj))
 	node.openFilesMutex.Lock()
@@ -90,7 +90,7 @@ func (me *fileSystemMount) unregisterFileHandle(handle uint64, node *inode) *ope
 	return opened
 }
 
-func (me *fileSystemMount) registerFileHandle(node *inode, dir rawDir, f File, flags uint32) (uint64, *openedFile) {
+func (me *fileSystemMount) registerFileHandle(node *Inode, dir rawDir, f File, flags uint32) (uint64, *openedFile) {
 	node.openFilesMutex.Lock()
 	defer node.openFilesMutex.Unlock()
 	b := &openedFile{

fuse/fsops.go

@@ -22,7 +22,7 @@ func (me *FileSystemConnector) Lookup(header *InHeader, name string) (out *Entry
 	return out, status
 }
 
-func (me *FileSystemConnector) internalMountLookup(mount *fileSystemMount, lookupCount int) (out *EntryOut, status Status, node *inode) {
+func (me *FileSystemConnector) internalMountLookup(mount *fileSystemMount, lookupCount int) (out *EntryOut, status Status, node *Inode) {
 	fi, err := mount.fs.Root().GetAttr(nil, nil)
 	if err == ENOENT && mount.options.NegativeTimeout > 0.0 {
 		return NegativeEntry(mount.options.NegativeTimeout), OK, nil
@@ -41,7 +41,7 @@ func (me *FileSystemConnector) internalMountLookup(mount *fileSystemMount, looku
 	return out, OK, mount.mountInode
 }
 
-func (me *FileSystemConnector) internalLookup(parent *inode, name string, lookupCount int, context *Context) (out *EntryOut, code Status, node *inode) {
+func (me *FileSystemConnector) internalLookup(parent *Inode, name string, lookupCount int, context *Context) (out *EntryOut, code Status, node *Inode) {
 	if mount := me.lookupMount(parent, name, lookupCount); mount != nil {
 		return me.internalMountLookup(mount, lookupCount)
 	}
@@ -199,7 +199,7 @@ func (me *FileSystemConnector) Mknod(header *InHeader, input *MknodIn, name stri
 	return out, code
 }
 
-func (me *FileSystemConnector) createChild(parent *inode, name string, fi *os.FileInfo, fsi FsNode) (out *EntryOut, child *inode) {
+func (me *FileSystemConnector) createChild(parent *Inode, name string, fi *os.FileInfo, fsi FsNode) (out *EntryOut, child *Inode) {
 	child = parent.createChild(name, fi.IsDirectory(), fsi, me)
 	out = parent.mount.fileInfoToEntry(fi)
 	out.Ino = child.nodeId

fuse/inode.go

@@ -6,7 +6,7 @@ import (
 )
 
 // The inode reflects the kernel's idea of the inode.
-type inode struct {
+type Inode struct {
 	handled Handled
 
 	// Constant during lifetime.
@@ -27,7 +27,7 @@ type inode struct {
 	// All data below is protected by treeLock.
 	fsInode     FsNode
 	
-	children    map[string]*inode
+	children    map[string]*Inode
 
 	// Contains directories that function as mounts. The entries
 	// are duplicated in children.
@@ -43,7 +43,47 @@ type inode struct {
 	mount *fileSystemMount
 }
 
-func (me *inode) createChild(name string, isDir bool, fsi FsNode, conn *FileSystemConnector) *inode {
+// public methods.
+
+// LockTree() Locks the mutex used for tree operations, and returns the
+// unlock function.
+func (me *Inode) LockTree() (func()) {
+	// TODO - this API is tricky.
+	me.treeLock.Lock()
+	return func() { me.treeLock.Unlock() }
+}
+
+// Returns any open file, preferably a r/w one.
+func (me *Inode) AnyFile() (file File) {
+	me.openFilesMutex.Lock()
+	defer me.openFilesMutex.Unlock()
+	
+	for _, f := range me.openFiles {
+		if file == nil || f.OpenFlags & O_ANYWRITE != 0 {
+			file = f.file
+		}
+	}
+	return file
+}
+
+// Returns an open writable file for the given Inode.
+func (me *Inode) WritableFiles() (files []File) {
+	me.openFilesMutex.Lock()
+	defer me.openFilesMutex.Unlock()
+
+	for _, f := range me.openFiles {
+		if f.OpenFlags & O_ANYWRITE != 0 {
+			files = append(files, f.file)
+		}
+	}
+	return files
+}
+
+func (me *Inode) IsDir() bool {
+	return me.children != nil
+}
+
+func (me *Inode) createChild(name string, isDir bool, fsi FsNode, conn *FileSystemConnector) *Inode {
 	me.treeLock.Lock()
 	defer me.treeLock.Unlock()
 
@@ -62,7 +102,7 @@ func (me *inode) createChild(name string, isDir bool, fsi FsNode, conn *FileSyst
 	return ch
 }
 
-func (me *inode) getChild(name string) (child *inode) {
+func (me *Inode) getChild(name string) (child *Inode) {
 	me.treeLock.Lock()
 	defer me.treeLock.Unlock()
 	
@@ -70,20 +110,22 @@ func (me *inode) getChild(name string) (child *inode) {
 }
 
 // Must be called with treeLock for the mount held.
-func (me *inode) addChild(name string, child *inode) {
+func (me *Inode) addChild(name string, child *Inode) {
 	if paranoia {
 		ch := me.children[name]
 		if ch != nil {
-			panic(fmt.Sprintf("Already have an inode with same name: %v: %v", name, ch))
+			panic(fmt.Sprintf("Already have an Inode with same name: %v: %v", name, ch))
 		}
 	}
-
 	me.children[name] = child
-	me.fsInode.AddChild(name, child.fsInode)
+
+	if child.mountPoint == nil {
+		me.fsInode.AddChild(name, child.fsInode)
+	}
 }
 
 // Must be called with treeLock for the mount held.
-func (me *inode) rmChild(name string) (ch *inode) {
+func (me *Inode) rmChild(name string) (ch *Inode) {
 	ch = me.children[name]
 	if ch != nil {
 		me.children[name] = nil, false
@@ -93,7 +135,7 @@ func (me *inode) rmChild(name string) (ch *inode) {
 }
 
 // Can only be called on untouched inodes.
-func (me *inode) mountFs(fs *inodeFs, opts *FileSystemOptions) {
+func (me *Inode) mountFs(fs NodeFileSystem, opts *FileSystemOptions) {
 	me.mountPoint = &fileSystemMount{
 		fs:         fs,
 		openFiles:  NewHandleMap(true),
@@ -107,7 +149,7 @@ func (me *inode) mountFs(fs *inodeFs, opts *FileSystemOptions) {
 }
 
 // Must be called with treeLock held.
-func (me *inode) canUnmount() bool {
+func (me *Inode) canUnmount() bool {
 	for _, v := range me.children {
 		if v.mountPoint != nil {
 			// This access may be out of date, but it is no
@@ -124,11 +166,7 @@ func (me *inode) canUnmount() bool {
 	return len(me.openFiles) == 0
 }
 
-func (me *inode) IsDir() bool {
-	return me.children != nil
-}
-
-func (me *inode) getMountDirEntries() (out []DirEntry) {
+func (me *Inode) getMountDirEntries() (out []DirEntry) {
 	me.treeLock.RLock()
 	defer me.treeLock.RUnlock()
 
@@ -141,35 +179,9 @@ func (me *inode) getMountDirEntries() (out []DirEntry) {
 	return out
 }
 
-// Returns any open file, preferably a r/w one.
-func (me *inode) getAnyFile() (file File) {
-	me.openFilesMutex.Lock()
-	defer me.openFilesMutex.Unlock()
-	
-	for _, f := range me.openFiles {
-		if file == nil || f.OpenFlags & O_ANYWRITE != 0 {
-			file = f.file
-		}
-	}
-	return file
-}
-
-// Returns an open writable file for the given inode.
-func (me *inode) getWritableFiles() (files []File) {
-	me.openFilesMutex.Lock()
-	defer me.openFilesMutex.Unlock()
-
-	for _, f := range me.openFiles {
-		if f.OpenFlags & O_ANYWRITE != 0 {
-			files = append(files, f.file)
-		}
-	}
-	return files
-}
-
 const initDirSize = 20
 
-func (me *inode) verify(cur *fileSystemMount) {
+func (me *Inode) verify(cur *fileSystemMount) {
 	if me.mountPoint != nil {
 		if me != me.mountPoint.mountInode {
 			panic("mountpoint mismatch")