configfs: accessing item hierarchy during rmdir(2)

[safe/jmp/linux-2.6] / Documentation / filesystems / configfs / configfs.txt

diff --git a/Documentation/filesystems/configfs/configfs.txt b/Documentation/filesystems/configfs/configfs.txt
index 21f038e..aef74cd 100644 (file)
--- a/Documentation/filesystems/configfs/configfs.txt
+++ b/Documentation/filesystems/configfs/configfs.txt
@@ -238,6 +238,8 @@ config_item_type.
                struct config_group *(*make_group)(struct config_group *group,
                                                   const char *name);
                int (*commit_item)(struct config_item *item);
+               void (*disconnect_notify)(struct config_group *group,
+                                         struct config_item *item);
                void (*drop_item)(struct config_group *group,
                                  struct config_item *item);
        };
@@ -268,6 +270,16 @@ the item in other threads, the memory is safe.  It may take some time
 for the item to actually disappear from the subsystem's usage.  But it
 is gone from configfs.
 
+When drop_item() is called, the item's linkage has already been torn
+down.  It no longer has a reference on its parent and has no place in
+the item hierarchy.  If a client needs to do some cleanup before this
+teardown happens, the subsystem can implement the
+ct_group_ops->disconnect_notify() method.  The method is called after
+configfs has removed the item from the filesystem view but before the
+item is removed from its parent group.  Like drop_item(),
+disconnect_notify() is void and cannot fail.  Client subsystems should
+not drop any references here, as they still must do it in drop_item().
+
 A config_group cannot be removed while it still has child items.  This
 is implemented in the configfs rmdir(2) code.  ->drop_item() will not be
 called, as the item has not been dropped.  rmdir(2) will fail, as the