fsnotify: Remove fsnotify_duplicate_mark()

There are only two calls sites of fsnotify_duplicate_mark(). Those are
in kernel/audit_tree.c and both are bogus. Vfsmount pointer is unused
for audit tree, inode pointer and group gets set in
fsnotify_add_mark_locked() later anyway, mask and free_mark are already
set in alloc_chunk(). In fact, calling fsnotify_duplicate_mark() is
actively harmful because following fsnotify_add_mark_locked() will leak
group reference by overwriting the group pointer. So just remove the two
calls to fsnotify_duplicate_mark() and the function.
Signed-off-by: Jan Kara <jack@suse.cz>
[PM: line wrapping to fit in 80 chars]
Signed-off-by: Paul Moore <paul@paul-moore.com>

fs/notify/mark.c

@@ -510,18 +510,6 @@ void fsnotify_detach_group_marks(struct fsnotify_group *group)
 	}
 }
 
-void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old)
-{
-	assert_spin_locked(&old->lock);
-	new->inode = old->inode;
-	new->mnt = old->mnt;
-	if (old->group)
-		fsnotify_get_group(old->group);
-	new->group = old->group;
-	new->mask = old->mask;
-	new->free_mark = old->free_mark;
-}
-
 /*
  * Nothing fancy, just initialize lists and locks and counters.
  */

include/linux/fsnotify_backend.h

@@ -324,8 +324,6 @@ extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(str
 extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode);
 /* find (and take a reference) to a mark associated with group and vfsmount */
 extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt);
-/* copy the values from old into new */
-extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old);
 /* set the ignored_mask of a mark */
 extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask);
 /* set the mask of a mark (might pin the object into memory */

kernel/audit_tree.c

@@ -258,8 +258,8 @@ static void untag_chunk(struct node *p)
 	if (!new)
 		goto Fallback;
 
-	fsnotify_duplicate_mark(&new->mark, entry);
-	if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.inode, NULL, 1)) {
+	if (fsnotify_add_mark(&new->mark,
+			      entry->group, entry->inode, NULL, 1)) {
 		fsnotify_put_mark(&new->mark);
 		goto Fallback;
 	}
@@ -395,8 +395,8 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
 		return -ENOENT;
 	}
 
-	fsnotify_duplicate_mark(chunk_entry, old_entry);
-	if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->inode, NULL, 1)) {
+	if (fsnotify_add_mark(chunk_entry,
+			      old_entry->group, old_entry->inode, NULL, 1)) {
 		spin_unlock(&old_entry->lock);
 		fsnotify_put_mark(chunk_entry);
 		fsnotify_put_mark(old_entry);