fsnotify: correctly handle return codes from listeners

When fsnotify groups return errors they are ignored.  For permissions
events these should be passed back up the stack, but for most events these
should continue to be ignored.

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

fs/notify/fsnotify.c

@@ -252,20 +252,23 @@ int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
 
 		if (inode_group > vfsmount_group) {
 			/* handle inode */
-			send_to_group(to_tell, NULL, inode_mark, NULL, mask, data,
-				      data_is, cookie, file_name, &event);
+			ret = send_to_group(to_tell, NULL, inode_mark, NULL, mask, data,
+					    data_is, cookie, file_name, &event);
 			/* we didn't use the vfsmount_mark */
 			vfsmount_group = NULL;
 		} else if (vfsmount_group > inode_group) {
-			send_to_group(to_tell, mnt, NULL, vfsmount_mark, mask, data,
-				      data_is, cookie, file_name, &event);
+			ret = send_to_group(to_tell, mnt, NULL, vfsmount_mark, mask, data,
+					    data_is, cookie, file_name, &event);
 			inode_group = NULL;
 		} else {
-			send_to_group(to_tell, mnt, inode_mark, vfsmount_mark,
-				      mask, data, data_is, cookie, file_name,
-				      &event);
+			ret = send_to_group(to_tell, mnt, inode_mark, vfsmount_mark,
+					    mask, data, data_is, cookie, file_name,
+					    &event);
 		}
 
+		if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS))
+			goto out;
+
 		if (inode_group)
 			inode_node = srcu_dereference(inode_node->next,
 						      &fsnotify_mark_srcu);
@@ -273,7 +276,8 @@ int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
 			vfsmount_node = srcu_dereference(vfsmount_node->next,
 							 &fsnotify_mark_srcu);
 	}
-
+	ret = 0;
+out:
 	srcu_read_unlock(&fsnotify_mark_srcu, idx);
 	/*
 	 * fsnotify_create_event() took a reference so the event can't be cleaned

include/linux/fsnotify_backend.h

@@ -64,6 +64,8 @@
 
 #define FS_MOVE			(FS_MOVED_FROM | FS_MOVED_TO)
 
+#define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM)
+
 #define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
 			     FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN | \
 			     FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE | \