3 files changed, 41 insertions, 4 deletions

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 9fe760baf69f..84d3e2047de3 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -463,8 +463,6 @@ SYSCALL_DEFINE3(fanotify_init, unsigned int, flags, unsigned int, event_f_flags,
 
         if (event_f_flags)
                 return -EINVAL;
-        if (priority)
-                return -EINVAL;
 
         if (!capable(CAP_SYS_ADMIN))
                 return -EACCES;
@@ -483,6 +481,8 @@ SYSCALL_DEFINE3(fanotify_init, unsigned int, flags, unsigned int, event_f_flags,
         if (IS_ERR(group))
                 return PTR_ERR(group);
 
+        group->priority = priority;
+
         fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
         if (fd < 0)
                 goto out_put_group;
diff --git a/fs/notify/group.c b/fs/notify/group.c
index 9e9eb406afdd..ada913fd4f7f 100644
--- a/fs/notify/group.c
+++ b/fs/notify/group.c
@@ -89,10 +89,27 @@ void fsnotify_recalc_group_mask(struct fsnotify_group *group)
 
 void fsnotify_add_vfsmount_group(struct fsnotify_group *group)
 {
+        struct fsnotify_group *group_iter;
+        unsigned int priority = group->priority;
+
         mutex_lock(&fsnotify_grp_mutex);
 
-        if (!group->on_vfsmount_group_list)
+        if (!group->on_vfsmount_group_list) {
+                list_for_each_entry(group_iter, &fsnotify_vfsmount_groups,
+                                    vfsmount_group_list) {
+                        /* insert in front of this one? */
+                        if (priority < group_iter->priority) {
+                                /* list_add_tail() insert in front of group_iter */
+                                list_add_tail_rcu(&group->inode_group_list,
+                                                  &group_iter->inode_group_list);
+                                goto out;
+                        }
+                }
+
+                /* apparently we need to be the last entry */
                 list_add_tail_rcu(&group->vfsmount_group_list, &fsnotify_vfsmount_groups);
+        }
+out:
         group->on_vfsmount_group_list = 1;
 
         mutex_unlock(&fsnotify_grp_mutex);
@@ -100,10 +117,27 @@ void fsnotify_add_vfsmount_group(struct fsnotify_group *group)
 
 void fsnotify_add_inode_group(struct fsnotify_group *group)
 {
+        struct fsnotify_group *group_iter;
+        unsigned int priority = group->priority;
+
         mutex_lock(&fsnotify_grp_mutex);
 
-        if (!group->on_inode_group_list)
+        /* add to global group list, priority 0 first, UINT_MAX last */
+        if (!group->on_inode_group_list) {
+                list_for_each_entry(group_iter, &fsnotify_inode_groups,
+                                    inode_group_list) {
+                        if (priority < group_iter->priority) {
+                                /* list_add_tail() insert in front of group_iter */
+                                list_add_tail_rcu(&group->inode_group_list,
+                                                  &group_iter->inode_group_list);
+                                goto out;
+                        }
+                }
+
+                /* apparently we need to be the last entry */
                 list_add_tail_rcu(&group->inode_group_list, &fsnotify_inode_groups);
+        }
+out:
         group->on_inode_group_list = 1;
 
         mutex_unlock(&fsnotify_grp_mutex);
@@ -226,6 +260,8 @@ struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
         spin_lock_init(&group->mark_lock);
         INIT_LIST_HEAD(&group->marks_list);
 
+        group->priority = UINT_MAX;
+
         group->ops = ops;
 
         return group;
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;