1 files changed, 23 insertions, 1 deletions

diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 117794582f9f..b9b239fa5cfd 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -430,7 +430,7 @@ void ovl_inuse_unlock(struct dentry *dentry)
         }
 }
 
-/* Called must hold OVL_I(inode)->oi_lock */
+/* Caller must hold OVL_I(inode)->lock */
 static void ovl_cleanup_index(struct dentry *dentry)
 {
         struct inode *dir = ovl_indexdir(dentry->d_sb)->d_inode;
@@ -469,6 +469,9 @@ static void ovl_cleanup_index(struct dentry *dentry)
         err = PTR_ERR(index);
         if (!IS_ERR(index))
                 err = ovl_cleanup(dir, index);
+        else
+                index = NULL;
+
         inode_unlock(dir);
         if (err)
                 goto fail;
@@ -557,3 +560,22 @@ void ovl_nlink_end(struct dentry *dentry, bool locked)
                 mutex_unlock(&OVL_I(d_inode(dentry))->lock);
         }
 }
+
+int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir)
+{
+        /* Workdir should not be the same as upperdir */
+        if (workdir == upperdir)
+                goto err;
+
+        /* Workdir should not be subdir of upperdir and vice versa */
+        if (lock_rename(workdir, upperdir) != NULL)
+                goto err_unlock;
+
+        return 0;
+
+err_unlock:
+        unlock_rename(workdir, upperdir);
+err:
+        pr_err("overlayfs: failed to lock workdir+upperdir\n");
+        return -EIO;
+}