Added additional field and better documentation for ForgetInodeOp.

fuseops/ops.go

@@ -214,15 +214,31 @@ func (o *SetInodeAttributesOp) Respond(err error) {
 	o.r.(*bazilfuse.SetattrRequest).Respond(&resp)
 }
 
-// Forget an inode ID previously issued (e.g. by LookUpInode or MkDir). The
-// kernel sends this when removing an inode from its internal caches.
+// Decrement the reference count for an inode ID previously issued by the file
+// system. The comments for the ops that implicitly increment the reference
+// count contain a note of this. For example, LookUpInodeOp and MkDirOp.
+//
+// If the reference count hits zero, the file system can forget about that ID
+// entirely, and even re-use it in future responses. The kernel guarantees that
+// it will not otherwise use it again.
+//
+// The reference count corresponds to fuse_inode::nlookup
+// (http://goo.gl/ut48S4). Some examples of where the kernel manipulates it:
+//
+//  *  (http://goo.gl/vPD9Oh) Any caller to fuse_iget increases the count.
+//  *  (http://goo.gl/B6tTTC) fuse_lookup_name calls fuse_iget.
+//  *  (http://goo.gl/IlcxWv) fuse_create_open calls fuse_iget.
+//  *  (http://goo.gl/VQMQul) fuse_dentry_revalidate increments after
+//     revalidating.
+//
 type ForgetInodeOp struct {
 	commonOp
 
-	// The inode to be forgotten. The kernel guarantees that the node ID will not
-	// be used in further calls to the file system (unless it is reissued by the
-	// file system).
+	// The inode whose reference count should be decremented.
 	ID InodeID
+
+	// The amount to decrement the reference count.
+	N int
 }
 
 func (o *ForgetInodeOp) Respond(err error) {