fsnotify: implement ordering between notifiers
fanotify needs to be able to specify that some groups get events before
others. They use this idea to make sure that a hierarchical storage
manager gets access to files before programs which actually use them. This
is purely infrastructure. Everything will have a priority of 0, but the
infrastructure will exist for it to be non-zero.
Signed-off-by: Eric Paris <eparis@redhat.com>
diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c
index 21ed106..4c29fcf 100644
--- a/fs/notify/inode_mark.c
+++ b/fs/notify/inode_mark.c
@@ -177,7 +177,8 @@
* Attach an initialized mark to a given inode.
* These marks may be used for the fsnotify backend to determine which
* event types should be delivered to which group and for which inodes. These
- * marks are ordered according to the group's location in memory.
+ * marks are ordered according to priority, highest number first, and then by
+ * the group's location in memory.
*/
int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
struct fsnotify_group *group, struct inode *inode,
@@ -211,7 +212,11 @@
goto out;
}
- if (mark->group < lmark->group)
+ if (mark->group->priority < lmark->group->priority)
+ continue;
+
+ if ((mark->group->priority == lmark->group->priority) &&
+ (mark->group < lmark->group))
continue;
hlist_add_before_rcu(&mark->i.i_list, &lmark->i.i_list);