fsnotify: Move locking into fsnotify_recalc_mask()

Move locking of locks protecting a list of marks into
fsnotify_recalc_mask(). This reduces code churn in the following patch
which changes the lock protecting the list of marks.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/notify/dnotify/dnotify.c

@@ -69,8 +69,7 @@ static void dnotify_recalc_inode_mask(struct fsnotify_mark *fsn_mark)
 	if (old_mask == new_mask)
 		return;
 
-	if (fsn_mark->connector)
-		fsnotify_recalc_inode_mask(fsn_mark->connector->inode);
+	fsnotify_recalc_mask(fsn_mark->connector);
 }
 
 /*

fs/notify/fsnotify.h

@@ -14,9 +14,6 @@ extern void fsnotify_flush_notify(struct fsnotify_group *group);
 /* protects reads of inode and vfsmount marks list */
 extern struct srcu_struct fsnotify_mark_srcu;
 
-/* Calculate mask of events for a list of marks */
-extern u32 fsnotify_recalc_mask(struct fsnotify_mark_connector *conn);
-
 /* compare two groups for sorting of marks lists */
 extern int fsnotify_compare_groups(struct fsnotify_group *a,
 				   struct fsnotify_group *b);

fs/notify/inode_mark.c

@@ -30,17 +30,9 @@
 
 #include "../internal.h"
 
-/*
- * Recalculate the inode->i_fsnotify_mask, or the mask of all FS_* event types
- * any notifier is interested in hearing for this inode.
- */
 void fsnotify_recalc_inode_mask(struct inode *inode)
 {
-	spin_lock(&inode->i_lock);
-	inode->i_fsnotify_mask = fsnotify_recalc_mask(inode->i_fsnotify_marks);
-	spin_unlock(&inode->i_lock);
-
-	__fsnotify_update_child_dentry_flags(inode);
+	fsnotify_recalc_mask(inode->i_fsnotify_marks);
 }
 
 struct inode *fsnotify_destroy_inode_mark(struct fsnotify_mark *mark)
@@ -57,14 +49,10 @@ struct inode *fsnotify_destroy_inode_mark(struct fsnotify_mark *mark)
 	empty = hlist_empty(&mark->connector->list);
 	mark->connector = NULL;
 
-	/*
-	 * this mark is now off the inode->i_fsnotify_marks list and we
-	 * hold the inode->i_lock, so this is the perfect time to update the
-	 * inode->i_fsnotify_mask
-	 */
-	inode->i_fsnotify_mask = fsnotify_recalc_mask(inode->i_fsnotify_marks);
 	spin_unlock(&inode->i_lock);
 
+	fsnotify_recalc_mask(inode->i_fsnotify_marks);
+
 	return empty ? inode : NULL;
 }
 

fs/notify/mark.c

@@ -105,18 +105,40 @@ void fsnotify_put_mark(struct fsnotify_mark *mark)
 	}
 }
 
-/* Calculate mask of events for a list of marks */
-u32 fsnotify_recalc_mask(struct fsnotify_mark_connector *conn)
+static void __fsnotify_recalc_mask(struct fsnotify_mark_connector *conn)
 {
 	u32 new_mask = 0;
 	struct fsnotify_mark *mark;
 
-	if (!conn)
-		return 0;
-
 	hlist_for_each_entry(mark, &conn->list, obj_list)
 		new_mask |= mark->mask;
-	return new_mask;
+	if (conn->flags & FSNOTIFY_OBJ_TYPE_INODE)
+		conn->inode->i_fsnotify_mask = new_mask;
+	else if (conn->flags & FSNOTIFY_OBJ_TYPE_VFSMOUNT)
+		real_mount(conn->mnt)->mnt_fsnotify_mask = new_mask;
+}
+
+/*
+ * Calculate mask of events for a list of marks. The caller must make sure
+ * connector cannot disappear under us (usually by holding a mark->lock or
+ * mark->group->mark_mutex for a mark on this list).
+ */
+void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn)
+{
+	if (!conn)
+		return;
+
+	if (conn->flags & FSNOTIFY_OBJ_TYPE_INODE)
+		spin_lock(&conn->inode->i_lock);
+	else
+		spin_lock(&conn->mnt->mnt_root->d_lock);
+	__fsnotify_recalc_mask(conn);
+	if (conn->flags & FSNOTIFY_OBJ_TYPE_INODE) {
+		spin_unlock(&conn->inode->i_lock);
+		__fsnotify_update_child_dentry_flags(conn->inode);
+	} else {
+		spin_unlock(&conn->mnt->mnt_root->d_lock);
+	}
 }
 
 /*
@@ -423,10 +445,8 @@ int fsnotify_add_mark_locked(struct fsnotify_mark *mark,
 	if (ret)
 		goto err;
 
-	if (inode)
-		fsnotify_recalc_inode_mask(inode);
-	else
-		fsnotify_recalc_vfsmount_mask(mnt);
+	if (mark->mask)
+		fsnotify_recalc_mask(mark->connector);
 
 	return ret;
 err:

fs/notify/vfsmount_mark.c

@@ -34,17 +34,9 @@ void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group)
 	fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_OBJ_TYPE_VFSMOUNT);
 }
 
-/*
- * Recalculate the mnt->mnt_fsnotify_mask, or the mask of all FS_* event types
- * any notifier is interested in hearing for this mount point
- */
 void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt)
 {
-	struct mount *m = real_mount(mnt);
-
-	spin_lock(&mnt->mnt_root->d_lock);
-	m->mnt_fsnotify_mask = fsnotify_recalc_mask(m->mnt_fsnotify_marks);
-	spin_unlock(&mnt->mnt_root->d_lock);
+	fsnotify_recalc_mask(real_mount(mnt)->mnt_fsnotify_marks);
 }
 
 void fsnotify_destroy_vfsmount_mark(struct fsnotify_mark *mark)
@@ -60,8 +52,9 @@ void fsnotify_destroy_vfsmount_mark(struct fsnotify_mark *mark)
 	hlist_del_init_rcu(&mark->obj_list);
 	mark->connector = NULL;
 
-	m->mnt_fsnotify_mask = fsnotify_recalc_mask(m->mnt_fsnotify_marks);
 	spin_unlock(&mnt->mnt_root->d_lock);
+
+	fsnotify_recalc_mask(m->mnt_fsnotify_marks);
 }
 
 /*

include/linux/fsnotify_backend.h

@@ -327,6 +327,8 @@ extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group
 
 /* functions used to manipulate the marks attached to inodes */
 
+/* Calculate mask of events for a list of marks */
+extern void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn);
 /* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */
 extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt);
 /* run all marks associated with an inode and update inode->i_fsnotify_mask */