fsnotify: add group priorities

This introduces an ordering to fsnotify groups.  With purely asynchronous
notification based "things" implementing fsnotify (inotify, dnotify) ordering
isn't particularly important.  But if people want to use fsnotify for the
basis of sycronous notification or blocking notification ordering becomes
important.

eg. A Hierarchical Storage Management listener would need to get its event
before an AV scanner could get its event (since the HSM would need to
bring the data in for the AV scanner to scan.)  Typically asynchronous notification
would want to run after the AV scanner made any relevant access decisions
so as to not send notification about an event that was denied.

Signed-off-by: Eric Paris <eparis@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index be4a36ed2008..8b2e095e5907 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -140,6 +140,7 @@ struct fsnotify_group {
 					 * a group */
 	struct list_head marks_list;	/* all inode marks for this group */
 
+	unsigned int priority;		/* order of this group compared to others */
 	/* prevents double list_del of group_list.  protected by global fsnotify_grp_mutex */
 	bool on_inode_group_list;
 	bool on_vfsmount_group_list;