From 299894cc9001b09e3e9685f2709b49e7e1092ccc Mon Sep 17 00:00:00 2001 From: Joel Becker Date: Fri, 6 Oct 2006 17:33:23 -0700 Subject: 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 Signed-off-by: Mark Fasheh --- Documentation/filesystems/configfs/configfs.txt | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'Documentation/filesystems') diff --git a/Documentation/filesystems/configfs/configfs.txt b/Documentation/filesystems/configfs/configfs.txt index 21f038e66724..aef74cdecc21 100644 --- 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 -- cgit v1.2.3