[PATCH 1/6] fsnotify: introduce new group mutex

[Lino Sanfilippo <LinoSanfilippo@gmx.de>]

This patch intoduces a group specific mutex that is used to synchronize all 
group related data/tasks for which no dedicated lock exists yet. 

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
---
 fs/notify/group.c                |    1 +
 include/linux/fsnotify_backend.h |    1 +
 2 files changed, 2 insertions(+), 0 deletions(-)

Please apply this against commit 9f71741c75e5206e1fea72ddf2adf5661105444d of
branch 'origin/for-next' from git.infradead.org/users/eparis/notify.git

 Eric, as you can see i chose to introduce a new mutex instead of using the 
 notification_mutex since you may be right with you concerns about performance.
 I guess its ok since its what you preferred.

diff --git a/fs/notify/group.c b/fs/notify/group.c
index d309f38..cc341d3 100644
--- a/fs/notify/group.c
+++ b/fs/notify/group.c
@@ -90,6 +90,7 @@ struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
 	 */
 	atomic_set(&group->num_marks, 1);
 
+	mutex_init(&group->mutex);
 	mutex_init(&group->notification_mutex);
 	INIT_LIST_HEAD(&group->notification_list);
 	init_waitqueue_head(&group->notification_waitq);
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index add1351..6a3c660 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -125,6 +125,7 @@ struct fsnotify_group {
 
 	const struct fsnotify_ops *ops;	/* how this group handles things */
 
+	struct mutex mutex;
 	/* needed to send notification to userspace */
 	struct mutex notification_mutex;	/* protect the notification_list */
 	struct list_head notification_list;	/* list of event_holder this group needs to send to userspace */
-- 
1.5.6.5