fsnotify: move s_fsnotify_connectors into fsnotify_sb_info

Move the s_fsnotify_connectors counter into the per-sb fsnotify state.
Suggested-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20240317184154.1200192-9-amir73il@gmail.com>

include/linux/fs.h

@@ -1302,12 +1302,6 @@ struct super_block {
 	/* Number of inodes with nlink == 0 but still referenced */
 	atomic_long_t s_remove_count;
 
-	/*
-	 * Number of inode/mount/sb objects that are being watched, note that
-	 * inodes objects are currently double-accounted.
-	 */
-	atomic_long_t s_fsnotify_connectors;
-
 	/* Read-only state of the superblock is being changed */
 	int s_readonly_remount;
 

include/linux/fsnotify.h

@@ -20,7 +20,13 @@
 /* Are there any inode/mount/sb objects that are being watched at all? */
 static inline bool fsnotify_sb_has_watchers(struct super_block *sb)
 {
-	return atomic_long_read(fsnotify_sb_watched_objects(sb));
+	struct fsnotify_sb_info *sbinfo = fsnotify_sb_info(sb);
+
+	/* Were any marks ever added to any object on this sb? */
+	if (!sbinfo)
+		return false;
+
+	return atomic_long_read(&sbinfo->watched_objects);
 }
 
 /*

include/linux/fsnotify_backend.h

@@ -483,6 +483,11 @@ struct fsnotify_mark_connector {
  */
 struct fsnotify_sb_info {
 	struct fsnotify_mark_connector __rcu *sb_marks;
+	/*
+	 * Number of inode/mount/sb objects that are being watched in this sb.
+	 * Note that inodes objects are currently double-accounted.
+	 */
+	atomic_long_t watched_objects;
 };
 
 static inline struct fsnotify_sb_info *fsnotify_sb_info(struct super_block *sb)
@@ -496,7 +501,7 @@ static inline struct fsnotify_sb_info *fsnotify_sb_info(struct super_block *sb)
 
 static inline atomic_long_t *fsnotify_sb_watched_objects(struct super_block *sb)
 {
-	return &sb->s_fsnotify_connectors;
+	return &fsnotify_sb_info(sb)->watched_objects;
 }
 
 /*