fsnotify: add flags to fsnotify_mark_entries

To differentiate between inode and vfsmount (or other future) types of
marks we add a flags field and set the inode bit on inode marks (the only
currently supported type of mark)

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

fs/notify/inode_mark.c

@@ -322,6 +322,8 @@ int fsnotify_add_mark(struct fsnotify_mark_entry *entry,
 	if (unlikely(!inode))
 		return -EINVAL;
 
+	entry->flags = FSNOTIFY_MARK_FLAG_INODE;
+
 	/*
 	 * if this group isn't being testing for inode type events we need
 	 * to start testing

include/linux/fsnotify_backend.h

@@ -267,6 +267,9 @@ struct fsnotify_mark_entry {
 		struct fsnotify_vfsmount_mark m;
 	};
 	struct list_head free_g_list;	/* tmp list used when freeing this mark */
+#define FSNOTIFY_MARK_FLAG_INODE	0x01
+#define FSNOTIFY_MARK_FLAG_VFSMOUNT	0x02
+	unsigned int flags;		/* vfsmount or inode mark? */
 	void (*free_mark)(struct fsnotify_mark_entry *entry); /* called on final put+free */
 };