.

wcfs/misc.go

@@ -112,11 +112,17 @@ func asctx(fctx *fuse.Context) context.Context {
 // In wcfs we have dynamic files (e.g. /head/watch) and this way we have to
 // avoid returning ENOSYS on nodes, that do not need file handles.
 //
-// fsNode is like nodefs.defaultNode, but Open returns to kernel fh=0 and
-// FOPEN_KEEP_CACHE - similarly how openless case is handled there.
-type fsNode struct{
+// fsNode is like nodefs.defaultNode, but by default Open returns to kernel
+// fh=0 and FOPEN_KEEP_CACHE - similarly how openless case is handled there.
+//
+// fsNode behaviour can be additionally controlled via fsOptions.
+//
+// fsNode should be created via newFSNode.
+type fsNode struct {
 	nodefs.Node
 
+	opt *fsOptions
+
 	// cache for path
 	// we don't use hardlinks / don't want to pay locks + traversal price every time.
 	xpath atomic.Value
@@ -129,9 +135,23 @@ func (n *fsNode) Open(flags uint32, fctx *fuse.Context) (nodefs.File, fuse.Statu
 	}, fuse.OK
 }
 
-func newFSNode() fsNode { // NOTE not pointer
+// fsOptions allows to tune fsNode behaviour.
+type fsOptions struct {
+	// Sticky nodes are not removed from inode tree on FORGET.
+	// Correspondingly OnForget is never called on a sticky node.
+	Sticky bool
+}
+
+var fSticky = &fsOptions{Sticky: true} // frequently used shortcut XXX -> newFSticky?
+
+func (n *fsNode) Deletable() bool {
+	return !n.opt.Sticky
+}
+
+func newFSNode(opt *fsOptions) fsNode { // NOTE not pointer
 	return fsNode{
 		Node: nodefs.NewDefaultNode(),
+		opt:  opt,
 	}
 }
 
@@ -161,6 +181,8 @@ func (n *fsNode) path() string {
 
 
 // NewStaticFile creates nodefs.Node for file with static data.
+//
+// Created file is sticky.
 func NewStaticFile(data []byte) *SmallFile {
 	return newSmallFile(func() []byte {
 		return data
@@ -178,13 +200,15 @@ type SmallFile struct {
 
 func newSmallFile(readData func() []byte, fuseFlags uint32) *SmallFile {
 	return &SmallFile{
-		fsNode:    newFSNode(),
+		fsNode:    newFSNode(&fsOptions{Sticky: true}),
 		fuseFlags: fuseFlags,
 		readData:  readData,
 	}
 }
 
 // NewSmallFile creates nodefs.Node for file with dynamic, but always small, data.
+//
+// Created file is sticky.
 func NewSmallFile(readData func() []byte) *SmallFile {
 	return newSmallFile(readData, fuse.FOPEN_DIRECT_IO)
 }

wcfs/wcfs.go

@@ -1078,13 +1078,13 @@ func (root *Root) lookup(name string, fctx *fuse.Context) (_ *Head, err error) {
 
 	// XXX -> newHead()
 	revDir = &Head{
-		fsNode: newFSNode(),
+		fsNode: newFSNode(&fsOptions{Sticky: false}),	// XXX + Head.OnForget() -> del root.revTab[]
 		rev:    rev,
 		zconn:  zconnRev,
 	}
 
 	bfdir := &BigFileDir{
-		fsNode:      newFSNode(),
+		fsNode:      newFSNode(&fsOptions{Sticky: false}),	// XXX + BigFileDir.OnForget()
 		head:        revDir,
 		fileTab:     make(map[zodb.Oid]*BigFile),
 		indexLooked: nil, // δbtree index not needed/used for @revX/
@@ -1151,7 +1151,7 @@ func (head *Head) bigopen(ctx context.Context, oid zodb.Oid) (_ *BigFile, err er
 
 //	zconn.Incref()
 	f := &BigFile{
-		fsNode:  newFSNode(),
+		fsNode:  newFSNode(&fsOptions{Sticky: false}),	// XXX + BigFile.OnForget -> del .head.bfdir.fileTab[]
 		head:    head,
 		zbf:     zbf,
 		zbfSize: zbfSize,
@@ -1548,12 +1548,12 @@ func main() {
 	// mount root + head/
 	// XXX -> newHead()
 	head := &Head{
-		fsNode: newFSNode(),
+		fsNode: newFSNode(fSticky),
 		rev:    0,
 		zconn:  zhead,
 	}
 	bfdir := &BigFileDir{
-		fsNode:      newFSNode(),
+		fsNode:      newFSNode(fSticky),
 		head:        head,
 		fileTab:     make(map[zodb.Oid]*BigFile),
 		indexLooked: δbtree.NewPathSet(),
@@ -1561,7 +1561,7 @@ func main() {
 	head.bfdir = bfdir
 
 	root := &Root{
-		fsNode: newFSNode(),
+		fsNode: newFSNode(fSticky),
 		zstor:  zstor,
 		zdb:    zdb,
 		head:   head,
@@ -1601,7 +1601,7 @@ func main() {
 	mkfile(head, "at", NewSmallFile(head.readAt))   // TODO mtime(at) = tidtime(at)
 
 	// for debugging/testing
-	_wcfs := newFSNode()
+	_wcfs := newFSNode(fSticky)
 	mkdir(root, ".wcfs", &_wcfs)
 	mkfile(&_wcfs, "zurl", NewStaticFile([]byte(zurl)))
 
@@ -1612,7 +1612,7 @@ func main() {
 	// There can be multiple openers. Once opened, the file must be read,
 	// as wcfs blocks waiting for data to be read before XXX.
 	mkfile(&_wcfs, "zhead", &_wcfs_Zhead{
-		fsNode: newFSNode(),
+		fsNode: newFSNode(fSticky),
 	})
 
 	// XXX place = ok?