fsnotify: include vfsmount in should_send_event when appropriate

To ensure that a group will not duplicate events when it receives it based
on the vfsmount and the inode should_send_event test we should distinguish
those two cases.  We pass a vfsmount to this function so groups can make
their own determinations.

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

fs/notify/dnotify/dnotify.c

@@ -133,8 +133,8 @@ static int dnotify_handle_event(struct fsnotify_group *group,
  * userspace notification for that pair.
  */
 static bool dnotify_should_send_event(struct fsnotify_group *group,
-				      struct inode *inode, __u32 mask,
-				      void *data, int data_type)
+				      struct inode *inode, struct vfsmount *mnt,
+				      __u32 mask, void *data, int data_type)
 {
 	struct fsnotify_mark_entry *entry;
 	bool send;

fs/notify/fsnotify.c

@@ -135,13 +135,12 @@ void __fsnotify_parent(struct file *file, struct dentry *dentry, __u32 mask)
 }
 EXPORT_SYMBOL_GPL(__fsnotify_parent);
 
-static void send_to_group(__u32 mask,
-			  struct fsnotify_group *group,
-			  void *data, int data_is, const char *file_name,
-			  u32 cookie, struct fsnotify_event **event,
-			  struct inode *to_tell)
+static void send_to_group(struct fsnotify_group *group, struct inode *to_tell,
+			  struct vfsmount *mnt, __u32 mask, void *data,
+			  int data_is, u32 cookie, const char *file_name,
+			  struct fsnotify_event **event)
 {
-	if (!group->ops->should_send_event(group, to_tell, mask,
+	if (!group->ops->should_send_event(group, to_tell, mnt, mask,
 					   data, data_is))
 		return;
 	if (!*event) {
@@ -159,15 +158,9 @@ static void send_to_group(__u32 mask,
 	group->ops->handle_event(group, *event);
 }
 
-static bool needed_by_vfsmount(__u32 test_mask, void *data, int data_is)
+static bool needed_by_vfsmount(__u32 test_mask, struct vfsmount *mnt)
 {
-	struct path *path;
-
-	if (data_is == FSNOTIFY_EVENT_PATH)
-		path = (struct path *)data;
-	else if (data_is == FSNOTIFY_EVENT_FILE)
-		path = &((struct file *)data)->f_path;
-	else
+	if (!mnt)
 		return false;
 
 	/* hook in this when mnt->mnt_fsnotify_mask is defined */
@@ -184,6 +177,7 @@ void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, const
 {
 	struct fsnotify_group *group;
 	struct fsnotify_event *event = NULL;
+	struct vfsmount *mnt = NULL;
 	int idx;
 	/* global tests shouldn't care about events on child only the specific event */
 	__u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
@@ -198,10 +192,15 @@ void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, const
 	    !(test_mask & fsnotify_vfsmount_mask))
                 return;
 
+	if (data_is == FSNOTIFY_EVENT_PATH)
+		mnt = ((struct path *)data)->mnt;
+	else if (data_is == FSNOTIFY_EVENT_FILE)
+		mnt = ((struct file *)data)->f_path.mnt;
+
 	/* if this inode's directed listeners don't care and nothing on the vfsmount
 	 * listeners list cares, nothing to do */
 	if (!(test_mask & to_tell->i_fsnotify_mask) &&
-	    !needed_by_vfsmount(test_mask, data, data_is))
+	    !needed_by_vfsmount(test_mask, mnt))
                 return;
 
 	/*
@@ -214,16 +213,16 @@ void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, const
 	if (test_mask & to_tell->i_fsnotify_mask) {
 		list_for_each_entry_rcu(group, &fsnotify_inode_groups, inode_group_list) {
 			if (test_mask & group->mask) {
-				send_to_group(mask, group, data, data_is,
-					      file_name, cookie, &event, to_tell);
+				send_to_group(group, to_tell, NULL, mask, data, data_is,
+					      cookie, file_name, &event);
 			}
 		}
 	}
-	if (needed_by_vfsmount(test_mask, data, data_is)) {
+	if (needed_by_vfsmount(test_mask, mnt)) {
 		list_for_each_entry_rcu(group, &fsnotify_vfsmount_groups, vfsmount_group_list) {
 			if (test_mask & group->mask) {
-				send_to_group(mask, group, data, data_is,
-					      file_name, cookie, &event, to_tell);
+				send_to_group(group, to_tell, mnt, mask, data, data_is,
+					      cookie, file_name, &event);
 			}
 		}
 	}

fs/notify/inotify/inotify_fsnotify.c

@@ -141,7 +141,8 @@ static void inotify_freeing_mark(struct fsnotify_mark_entry *entry, struct fsnot
 }
 
 static bool inotify_should_send_event(struct fsnotify_group *group, struct inode *inode,
-				      __u32 mask, void *data, int data_type)
+				      struct vfsmount *mnt, __u32 mask, void *data,
+				      int data_type)
 {
 	struct fsnotify_mark_entry *entry;
 	bool send;

include/linux/fsnotify_backend.h

@@ -79,7 +79,8 @@ struct fsnotify_event_private_data;
  */
 struct fsnotify_ops {
 	bool (*should_send_event)(struct fsnotify_group *group, struct inode *inode,
-				  __u32 mask, void *data, int data_type);
+				  struct vfsmount *mnt, __u32 mask, void *data,
+				  int data_type);
 	int (*handle_event)(struct fsnotify_group *group, struct fsnotify_event *event);
 	void (*free_group_priv)(struct fsnotify_group *group);
 	void (*freeing_mark)(struct fsnotify_mark_entry *entry, struct fsnotify_group *group);

kernel/audit_tree.c

@@ -920,7 +920,8 @@ static void audit_tree_freeing_mark(struct fsnotify_mark_entry *entry, struct fs
 }
 
 static bool audit_tree_send_event(struct fsnotify_group *group, struct inode *inode,
-				  __u32 mask, void *data, int data_type)
+				  struct vfsmount *mnt, __u32 mask, void *data,
+				  int data_type)
 {
 	return 0;
 }

kernel/audit_watch.c

@@ -514,7 +514,8 @@ void audit_remove_watch_rule(struct audit_krule *krule)
 }
 
 static bool audit_watch_should_send_event(struct fsnotify_group *group, struct inode *inode,
-					  __u32 mask, void *data, int data_type)
+					  struct vfsmount *mnt, __u32 mask, void *data,
+					  int data_type)
 {
 	struct fsnotify_mark_entry *entry;
 	bool send;