fuse: clarify the calling convention for entry/delete notify.

fuse/nodefs/fsconnector.go

@@ -392,7 +392,8 @@ func (c *FileSystemConnector) FileNotify(node *Inode, off int64, length int64) f
 
 // EntryNotify makes the kernel forget the entry data from the given
 // name from a directory.  After this call, the kernel will issue a
-// new lookup request for the given name when necessary.
+// new lookup request for the given name when necessary. No filesystem
+// related locks should be held when calling this.
 func (c *FileSystemConnector) EntryNotify(node *Inode, name string) fuse.Status {
 	var nId uint64
 	if node == c.rootNode {
@@ -408,7 +409,8 @@ func (c *FileSystemConnector) EntryNotify(node *Inode, name string) fuse.Status
 }
 
 // DeleteNotify signals to the kernel that the named entry in dir for
-// the child disappeared.
+// the child disappeared. No filesystem related locks should be held
+// when calling this.
 func (c *FileSystemConnector) DeleteNotify(dir *Inode, child *Inode, name string) fuse.Status {
 	var nId uint64
 

fuse/server.go

@@ -401,7 +401,8 @@ func (ms *Server) InodeNotify(node uint64, off int64, length int64) Status {
 // DeleteNotify notifies the kernel that an entry is removed from a
 // directory.  In many cases, this is equivalent to EntryNotify,
 // except when the directory is in use, eg. as working directory of
-// some process.
+// some process. You should not hold any FUSE filesystem locks, as that
+// can lead to deadlock.
 func (ms *Server) DeleteNotify(parent uint64, child uint64, name string) Status {
 	if ms.kernelSettings.Minor < 18 {
 		return ms.EntryNotify(parent, name)
@@ -440,7 +441,8 @@ func (ms *Server) DeleteNotify(parent uint64, child uint64, name string) Status
 }
 
 // EntryNotify should be used if the existence status of an entry
-// within a directory changes.
+// within a directory changes. You should not hold any FUSE filesystem
+// locks, as that can lead to deadlock.
 func (ms *Server) EntryNotify(parent uint64, name string) Status {
 	req := request{
 		inHeader: &InHeader{