[PATCH v7 21/28] fanotify: Support merging of error events

@@ -111,6 +111,16 @@ static bool fanotify_name_event_equal(struct fanotify_name_event *fne1,
 	return fanotify_info_equal(info1, info2);
 }
 
+static bool fanotify_error_event_equal(struct fanotify_error_event *fee1,
+				       struct fanotify_error_event *fee2)
+{
+	/* Error events against the same file system are always merged. */
+	if (!fanotify_fsid_equal(&fee1->fsid, &fee2->fsid))
+		return false;
+
+	return true;
+}
+
 static bool fanotify_should_merge(struct fanotify_event *old,
 				  struct fanotify_event *new)
 {

@@ -141,6 +151,9 @@ static bool fanotify_should_merge(struct fanotify_event *old,
 	case FANOTIFY_EVENT_TYPE_FID_NAME:
 		return fanotify_name_event_equal(FANOTIFY_NE(old),
 						 FANOTIFY_NE(new));
+	case FANOTIFY_EVENT_TYPE_FS_ERROR:
+		return fanotify_error_event_equal(FANOTIFY_EE(old),
+						  FANOTIFY_EE(new));
 	default:
 		WARN_ON_ONCE(1);
 	}

@@ -148,6 +161,22 @@ static bool fanotify_should_merge(struct fanotify_event *old,
 	return false;
 }
 
+static void fanotify_merge_error_event(struct fanotify_error_event *dest,
+				       struct fanotify_error_event *origin)
+{
+	dest->err_count++;
+}
+
+static void fanotify_merge_event(struct fanotify_event *dest,
+				 struct fanotify_event *origin)
+{
+	dest->mask |= origin->mask;
+
+	if (origin->type == FANOTIFY_EVENT_TYPE_FS_ERROR)
+		fanotify_merge_error_event(FANOTIFY_EE(dest),
+					   FANOTIFY_EE(origin));
+}
+
 /* Limit event merges to limit CPU overhead per event */
 #define FANOTIFY_MAX_MERGE_EVENTS 128
 

@@ -175,7 +204,7 @@ static int fanotify_merge(struct fsnotify_group *group,
 		if (++i > FANOTIFY_MAX_MERGE_EVENTS)
 			break;
 		if (fanotify_should_merge(old, new)) {
-			old->mask |= new->mask;
+			fanotify_merge_event(old, new);
 			return 1;
 		}
 	}

@@ -577,7 +606,8 @@ static struct fanotify_event *fanotify_alloc_name_event(struct inode *id,
 static struct fanotify_event *fanotify_alloc_error_event(
 						struct fsnotify_group *group,
 						__kernel_fsid_t *fsid,
-						const void *data, int data_type)
+						const void *data, int data_type,
+						unsigned int *hash)
 {
 	struct fs_error_report *report =
 			fsnotify_data_error_report(data, data_type);

@@ -591,6 +621,9 @@ static struct fanotify_event *fanotify_alloc_error_event(
 		return NULL;
 
 	fee->fae.type = FANOTIFY_EVENT_TYPE_FS_ERROR;
+	fee->err_count = 1;
+
+	*hash ^= fanotify_hash_fsid(fsid);
 
 	return &fee->fae;
 }

@@ -664,7 +697,7 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
 		event = fanotify_alloc_perm_event(path, gfp);
 	} else if (fanotify_is_error_event(mask)) {
 		event = fanotify_alloc_error_event(group, fsid, data,
-						   data_type);
+						   data_type, &hash);
 	} else if (name_event && (file_name || child)) {
 		event = fanotify_alloc_name_event(id, fsid, file_name, child,
 						  &hash, gfp);

@@ -199,6 +199,9 @@ FANOTIFY_NE(struct fanotify_event *event)
 
 struct fanotify_error_event {
 	struct fanotify_event fae;
+	u32 err_count; /* Suppressed errors count */
+
+	__kernel_fsid_t fsid; /* FSID this error refers to. */
 };
 
 static inline struct fanotify_error_event *

@@ -332,7 +335,6 @@ static inline struct path *fanotify_event_path(struct fanotify_event *event)
 static inline bool fanotify_is_hashed_event(u32 mask)
 {
 	return !(fanotify_is_perm_event(mask) ||
-		 fanotify_is_error_event(mask) ||
 		 fsnotify_is_overflow_event(mask));
 }