fsnotify: Add group pointer in fsnotify_init_mark()

Currently we initialize mark->group only in fsnotify_add_mark_lock().
However we will need to access fsnotify_ops of corresponding group from
fsnotify_put_mark() so we need mark->group initialized earlier. Do that
in fsnotify_init_mark() which has a consequence that once
fsnotify_init_mark() is called on a mark, the mark has to be destroyed
by fsnotify_put_mark().

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

@@ -305,7 +305,7 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
 
 	/* set up the new_fsn_mark and new_dn_mark */
 	new_fsn_mark = &new_dn_mark->fsn_mark;
-	fsnotify_init_mark(new_fsn_mark, dnotify_free_mark);
+	fsnotify_init_mark(new_fsn_mark, dnotify_group, dnotify_free_mark);
 	new_fsn_mark->mask = mask;
 	new_dn_mark->dn = NULL;
 
@@ -318,8 +318,7 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
 		dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark);
 		spin_lock(&fsn_mark->lock);
 	} else {
-		fsnotify_add_mark_locked(new_fsn_mark, dnotify_group, inode,
-					 NULL, 0);
+		fsnotify_add_mark_locked(new_fsn_mark, inode, NULL, 0);
 		spin_lock(&new_fsn_mark->lock);
 		fsn_mark = new_fsn_mark;
 		dn_mark = new_dn_mark;

fs/notify/fanotify/fanotify_user.c

@@ -628,8 +628,8 @@ static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
 	if (!mark)
 		return ERR_PTR(-ENOMEM);
 
-	fsnotify_init_mark(mark, fanotify_free_mark);
-	ret = fsnotify_add_mark_locked(mark, group, inode, mnt, 0);
+	fsnotify_init_mark(mark, group, fanotify_free_mark);
+	ret = fsnotify_add_mark_locked(mark, inode, mnt, 0);
 	if (ret) {
 		fsnotify_put_mark(mark);
 		return ERR_PTR(ret);

fs/notify/inotify/inotify_user.c

@@ -558,7 +558,7 @@ static int inotify_new_watch(struct fsnotify_group *group,
 	if (unlikely(!tmp_i_mark))
 		return -ENOMEM;
 
-	fsnotify_init_mark(&tmp_i_mark->fsn_mark, inotify_free_mark);
+	fsnotify_init_mark(&tmp_i_mark->fsn_mark, group, inotify_free_mark);
 	tmp_i_mark->fsn_mark.mask = mask;
 	tmp_i_mark->wd = -1;
 
@@ -574,8 +574,7 @@ static int inotify_new_watch(struct fsnotify_group *group,
 	}
 
 	/* we are on the idr, now get on the inode */
-	ret = fsnotify_add_mark_locked(&tmp_i_mark->fsn_mark, group, inode,
-				       NULL, 0);
+	ret = fsnotify_add_mark_locked(&tmp_i_mark->fsn_mark, inode, NULL, 0);
 	if (ret) {
 		/* we failed to get on the inode, get off the idr */
 		inotify_remove_from_idr(group, tmp_i_mark);

fs/notify/mark.c

@@ -563,10 +563,10 @@ out_err:
  * These marks may be used for the fsnotify backend to determine which
  * event types should be delivered to which group.
  */
-int fsnotify_add_mark_locked(struct fsnotify_mark *mark,
-			     struct fsnotify_group *group, struct inode *inode,
+int fsnotify_add_mark_locked(struct fsnotify_mark *mark, struct inode *inode,
 			     struct vfsmount *mnt, int allow_dups)
 {
+	struct fsnotify_group *group = mark->group;
 	int ret = 0;
 
 	BUG_ON(inode && mnt);
@@ -582,8 +582,6 @@ int fsnotify_add_mark_locked(struct fsnotify_mark *mark,
 	spin_lock(&mark->lock);
 	mark->flags |= FSNOTIFY_MARK_FLAG_ALIVE | FSNOTIFY_MARK_FLAG_ATTACHED;
 
-	fsnotify_get_group(group);
-	mark->group = group;
 	list_add(&mark->g_list, &group->marks_list);
 	atomic_inc(&group->num_marks);
 	fsnotify_get_mark(mark); /* for g_list */
@@ -608,12 +606,14 @@ err:
 	return ret;
 }
 
-int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group,
-		      struct inode *inode, struct vfsmount *mnt, int allow_dups)
+int fsnotify_add_mark(struct fsnotify_mark *mark, struct inode *inode,
+		      struct vfsmount *mnt, int allow_dups)
 {
 	int ret;
+	struct fsnotify_group *group = mark->group;
+
 	mutex_lock(&group->mark_mutex);
-	ret = fsnotify_add_mark_locked(mark, group, inode, mnt, allow_dups);
+	ret = fsnotify_add_mark_locked(mark, inode, mnt, allow_dups);
 	mutex_unlock(&group->mark_mutex);
 	return ret;
 }
@@ -732,12 +732,15 @@ void fsnotify_destroy_marks(struct fsnotify_mark_connector __rcu **connp)
  * Nothing fancy, just initialize lists and locks and counters.
  */
 void fsnotify_init_mark(struct fsnotify_mark *mark,
+			struct fsnotify_group *group,
 			void (*free_mark)(struct fsnotify_mark *mark))
 {
 	memset(mark, 0, sizeof(*mark));
 	spin_lock_init(&mark->lock);
 	atomic_set(&mark->refcnt, 1);
 	mark->free_mark = free_mark;
+	fsnotify_get_group(group);
+	mark->group = group;
 }
 
 /*

include/linux/fsnotify_backend.h

@@ -340,15 +340,17 @@ extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group
 
 /* Calculate mask of events for a list of marks */
 extern void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn);
-extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark));
+extern void fsnotify_init_mark(struct fsnotify_mark *mark,
+			       struct fsnotify_group *group,
+			       void (*free_mark)(struct fsnotify_mark *mark));
 /* Find mark belonging to given group in the list of marks */
 extern struct fsnotify_mark *fsnotify_find_mark(
 				struct fsnotify_mark_connector __rcu **connp,
 				struct fsnotify_group *group);
-/* attach the mark to both the group and the inode */
-extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group,
-			     struct inode *inode, struct vfsmount *mnt, int allow_dups);
-extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark, struct fsnotify_group *group,
+/* attach the mark to the inode or vfsmount */
+extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct inode *inode,
+			     struct vfsmount *mnt, int allow_dups);
+extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark,
 				    struct inode *inode, struct vfsmount *mnt, int allow_dups);
 /* given a group and a mark, flag mark to be freed when all references are dropped */
 extern void fsnotify_destroy_mark(struct fsnotify_mark *mark,

kernel/audit_fsnotify.c

@@ -103,15 +103,16 @@ struct audit_fsnotify_mark *audit_alloc_mark(struct audit_krule *krule, char *pa
 		goto out;
 	}
 
-	fsnotify_init_mark(&audit_mark->mark, audit_fsnotify_free_mark);
+	fsnotify_init_mark(&audit_mark->mark, audit_fsnotify_group,
+			   audit_fsnotify_free_mark);
 	audit_mark->mark.mask = AUDIT_FS_EVENTS;
 	audit_mark->path = pathname;
 	audit_update_mark(audit_mark, dentry->d_inode);
 	audit_mark->rule = krule;
 
-	ret = fsnotify_add_mark(&audit_mark->mark, audit_fsnotify_group, inode, NULL, true);
+	ret = fsnotify_add_mark(&audit_mark->mark, inode, NULL, true);
 	if (ret < 0) {
-		audit_fsnotify_mark_free(audit_mark);
+		fsnotify_put_mark(&audit_mark->mark);
 		audit_mark = ERR_PTR(ret);
 	}
 out:

kernel/audit_tree.c

@@ -154,7 +154,8 @@ static struct audit_chunk *alloc_chunk(int count)
 		INIT_LIST_HEAD(&chunk->owners[i].list);
 		chunk->owners[i].index = i;
 	}
-	fsnotify_init_mark(&chunk->mark, audit_tree_destroy_watch);
+	fsnotify_init_mark(&chunk->mark, audit_tree_group,
+			   audit_tree_destroy_watch);
 	chunk->mark.mask = FS_IN_IGNORED;
 	return chunk;
 }
@@ -262,7 +263,7 @@ static void untag_chunk(struct node *p)
 		spin_unlock(&entry->lock);
 		mutex_unlock(&entry->group->mark_mutex);
 		if (new)
-			free_chunk(new);
+			fsnotify_put_mark(&new->mark);
 		goto out;
 	}
 
@@ -286,8 +287,8 @@ static void untag_chunk(struct node *p)
 	if (!new)
 		goto Fallback;
 
-	if (fsnotify_add_mark_locked(&new->mark, entry->group,
-				     entry->connector->inode, NULL, 1)) {
+	if (fsnotify_add_mark_locked(&new->mark, entry->connector->inode,
+				     NULL, 1)) {
 		fsnotify_put_mark(&new->mark);
 		goto Fallback;
 	}
@@ -352,7 +353,7 @@ static int create_chunk(struct inode *inode, struct audit_tree *tree)
 		return -ENOMEM;
 
 	entry = &chunk->mark;
-	if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) {
+	if (fsnotify_add_mark(entry, inode, NULL, 0)) {
 		fsnotify_put_mark(entry);
 		return -ENOSPC;
 	}
@@ -428,11 +429,11 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
 		spin_unlock(&old_entry->lock);
 		mutex_unlock(&old_entry->group->mark_mutex);
 		fsnotify_put_mark(old_entry);
-		free_chunk(chunk);
+		fsnotify_put_mark(&chunk->mark);
 		return -ENOENT;
 	}
 
-	if (fsnotify_add_mark_locked(chunk_entry, old_entry->group,
+	if (fsnotify_add_mark_locked(chunk_entry,
 			     old_entry->connector->inode, NULL, 1)) {
 		spin_unlock(&old_entry->lock);
 		mutex_unlock(&old_entry->group->mark_mutex);

kernel/audit_watch.c

@@ -157,9 +157,10 @@ static struct audit_parent *audit_init_parent(struct path *path)
 
 	INIT_LIST_HEAD(&parent->watches);
 
-	fsnotify_init_mark(&parent->mark, audit_watch_free_mark);
+	fsnotify_init_mark(&parent->mark, audit_watch_group,
+			   audit_watch_free_mark);
 	parent->mark.mask = AUDIT_FS_WATCH;
-	ret = fsnotify_add_mark(&parent->mark, audit_watch_group, inode, NULL, 0);
+	ret = fsnotify_add_mark(&parent->mark, inode, NULL, 0);
 	if (ret < 0) {
 		audit_free_parent(parent);
 		return ERR_PTR(ret);