fsnotify: clear ignored mask on modify

On inode modification we clear the ignored mask for all of the marks on the
inode.  This allows userspace to ignore accesses to inodes until there is
something different.
Signed-off-by: NEric Paris <eparis@redhat.com>

fs/notify/fsnotify.c

@@ -140,6 +140,33 @@ void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
 }
 EXPORT_SYMBOL_GPL(__fsnotify_parent);
 
+void __fsnotify_flush_ignored_mask(struct inode *inode, void *data, int data_is)
+{
+	struct fsnotify_mark *mark;
+	struct hlist_node *node;
+
+	if (!hlist_empty(&inode->i_fsnotify_marks)) {
+		spin_lock(&inode->i_lock);
+		hlist_for_each_entry(mark, node, &inode->i_fsnotify_marks, i.i_list) {
+			mark->ignored_mask = 0;
+		}
+		spin_unlock(&inode->i_lock);
+	}
+
+	if (data_is == FSNOTIFY_EVENT_PATH) {
+		struct vfsmount *mnt;
+
+		mnt = ((struct path *)data)->mnt;
+		if (mnt && !hlist_empty(&mnt->mnt_fsnotify_marks)) {
+			spin_lock(&mnt->mnt_root->d_lock);
+			hlist_for_each_entry(mark, node, &mnt->mnt_fsnotify_marks, m.m_list) {
+				mark->ignored_mask = 0;
+			}
+			spin_unlock(&mnt->mnt_root->d_lock);
+		}
+	}
+}
+
 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,
@@ -170,6 +197,7 @@ static bool needed_by_vfsmount(__u32 test_mask, struct vfsmount *mnt)
 
 	return (test_mask & mnt->mnt_fsnotify_mask);
 }
+
 /*
  * This is the main call to fsnotify.  The VFS calls into hook specific functions
  * in linux/fsnotify.h.  Those functions then in turn call here.  Here will call
@@ -190,6 +218,9 @@ void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, const
 	    list_empty(&fsnotify_vfsmount_groups))
                 return;
  
+	if (mask & FS_MODIFY)
+		__fsnotify_flush_ignored_mask(to_tell, data, data_is);
+
 	/* if none of the directed listeners or vfsmount listeners care */
 	if (!(test_mask & fsnotify_inode_mask) &&
 	    !(test_mask & fsnotify_vfsmount_mask))