configfs: accessing item hierarchy during rmdir(2)
Add a notification callback, ops->disconnect_notify(). It has the same
prototype as ->drop_item(), but it will be called just before the item
linkage is broken. This way, configfs users who want to do work while
the object is still in the heirarchy have a chance.
Client drivers will still need to config_item_put() in their
->drop_item(), if they implement it. They need do nothing in
->disconnect_notify(). They don't have to provide it if they don't
care. But someone who wants to be notified before ci_parent is set to
NULL can now be notified.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
diff --git a/Documentation/filesystems/configfs/configfs.txt b/Documentation/filesystems/configfs/configfs.txt
index 21f038e..aef74cd 100644
--- a/Documentation/filesystems/configfs/configfs.txt
+++ b/Documentation/filesystems/configfs/configfs.txt
@@ -238,6 +238,8 @@
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 @@
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