Introduce Deletable() in node API, rather than hardcoded synthetic variable.

fuse/api.go

@@ -29,8 +29,14 @@ type FsNode interface {
 	SetInode(node *Inode)
 
 	Lookup(name string, context *Context) (fi *os.FileInfo, node FsNode, code Status)
-	OnForget()
 
+	// Deletable() should return true if this inode may be
+	// discarded from the children list. This will be called from
+	// within the treeLock critical section, so you cannot look at
+	// other inodes.
+	Deletable() bool
+	OnForget()
+	
 	// Misc.
 	Access(mode uint32, context *Context) (code Status)
 	Readlink(c *Context) ([]byte, Status)

fuse/defaultnode.go

@@ -39,6 +39,10 @@ func (me *DefaultFsNode) SetInode(node *Inode) {
 	me.inode = node
 }
 
+func (me *DefaultFsNode) Deletable() bool {
+	return true
+}
+
 func (me *DefaultFsNode) Inode() *Inode {
 	return me.inode
 }

fuse/fsconnector.go

@@ -161,7 +161,7 @@ func (me *FileSystemConnector) recursiveConsiderDropInode(n *Inode) (drop bool)
 		ch.fsInode.OnForget()
 	}
 
-	if len(n.children) > 0 || n.lookupCount > 0 || n.synthetic {
+	if len(n.children) > 0 || n.lookupCount > 0 || !n.FsNode().Deletable() {
 		return false
 	}
 	if n == me.rootNode || n.mountPoint != nil {

fuse/inode.go

@@ -52,12 +52,10 @@ type Inode struct {
 	//
 	// The lookupCount is exclusively used for managing the
 	// lifetime of nodeId variable.  It is ok for a node to have 0
-	// == lookupCount.  This can happen if the inode is synthetic.
+	// == lookupCount.  This can happen if the inode return false
+	// for Deletable().
 	lookupCount int
 
-	// This is to prevent lookupCount==0 node from being dropped.
-	synthetic bool
-
 	// Non-nil if this inode is a mountpoint, ie. the Root of a
 	// NodeFileSystem.
 	mountPoint *fileSystemMount
@@ -135,13 +133,6 @@ func (me *Inode) IsDir() bool {
 	return me.children != nil
 }
 
-// CreateChild() creates node for synthetic use
-func (me *Inode) NewSynthetic(isDir bool, fsi FsNode) *Inode {
-	ch := me.New(isDir, fsi)
-	ch.synthetic = true
-	return ch
-}
-
 func (me *Inode) New(isDir bool, fsi FsNode) *Inode {
 	ch := newInode(isDir, fsi)
 	ch.mount = me.mount

fuse/memnode.go

@@ -62,7 +62,7 @@ type memNode struct {
 
 func (me *memNode) newNode(isdir bool) *memNode {
 	n := me.fs.newNode()
-	me.Inode().NewSynthetic(isdir, n)
+	me.Inode().New(isdir, n)
 	return n
 }
 

zipfs/memtree.go

@@ -92,6 +92,10 @@ func (me *memNode) Open(flags uint32, context *fuse.Context) (fuseFile fuse.File
 	return fuse.NewDataFile(me.file.Data()), fuse.OK
 }
 
+func (me *memNode) Deletable() bool {
+	return false
+}
+
 func (me *memNode) GetAttr(file fuse.File, context *fuse.Context) (*os.FileInfo, fuse.Status) {
 	if me.Inode().IsDir() {
 		return &os.FileInfo{
@@ -114,7 +118,7 @@ func (me *MemTreeFs) addFile(name string, f MemFile) {
 				fsnode.file = f
 			}
 
-			child = node.NewSynthetic(fsnode.file == nil, fsnode)
+			child = node.New(fsnode.file == nil, fsnode)
 			node.AddChild(c, child)
 		}
 		node = child