Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/…

…kernel/git/mszeredi/vfs

Pull overlayfs fixes from Miklos Szeredi:
 "Fix two bugs in copy-up code. One introduced in 4.11 and one in
  4.12-rc"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: don't set origin on broken lower hardlink
  ovl: copy-up: don't unlock between lookup and link

fs/overlayfs/copy_up.c

@@ -330,15 +330,9 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
 		.link = link
 	};
 
-	upper = lookup_one_len(dentry->d_name.name, upperdir,
-			       dentry->d_name.len);
-	err = PTR_ERR(upper);
-	if (IS_ERR(upper))
-		goto out;
-
 	err = security_inode_copy_up(dentry, &new_creds);
 	if (err < 0)
-		goto out1;
+		goto out;
 
 	if (new_creds)
 		old_creds = override_creds(new_creds);
@@ -362,7 +356,7 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
 	}
 
 	if (err)
-		goto out2;
+		goto out;
 
 	if (S_ISREG(stat->mode)) {
 		struct path upperpath;
@@ -398,10 +392,23 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
 	/*
 	 * Store identifier of lower inode in upper inode xattr to
 	 * allow lookup of the copy up origin inode.
+	 *
+	 * Don't set origin when we are breaking the association with a lower
+	 * hard link.
 	 */
-	err = ovl_set_origin(dentry, lowerpath->dentry, temp);
-	if (err)
+	if (S_ISDIR(stat->mode) || stat->nlink == 1) {
+		err = ovl_set_origin(dentry, lowerpath->dentry, temp);
+		if (err)
+			goto out_cleanup;
+	}
+
+	upper = lookup_one_len(dentry->d_name.name, upperdir,
+			       dentry->d_name.len);
+	if (IS_ERR(upper)) {
+		err = PTR_ERR(upper);
+		upper = NULL;
 		goto out_cleanup;
+	}
 
 	if (tmpfile)
 		err = ovl_do_link(temp, udir, upper, true);
@@ -416,17 +423,15 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
 
 	/* Restore timestamps on parent (best effort) */
 	ovl_set_timestamps(upperdir, pstat);
-out2:
+out:
 	dput(temp);
-out1:
 	dput(upper);
-out:
 	return err;
 
 out_cleanup:
 	if (!tmpfile)
 		ovl_cleanup(wdir, temp);
-	goto out2;
+	goto out;
 }
 
 /*