From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 78CF3C31E45 for ; Thu, 13 Jun 2019 16:11:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4E12D20679 for ; Thu, 13 Jun 2019 16:11:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560442269; bh=Y1WnJruasGRm3U9AQ0OHPrzS3NNHvnFoLXqzcfF6xUc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=c/R7ByAMpP3rUBCGdDwgt1IetYz5HH7xtCvk/ma7nhSXVE6cL2ljn+ooI7+xweiWR Gj1obR8LEz5n1B+Broo7FABZmn7XmMkZZyq3wPiYT44zGcObwWDyzHCBBRCbHF2HbR RSDoYbVp5uYnunO2SQiA63svb4boB7NdDq05l2zg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391516AbfFMQLI (ORCPT ); Thu, 13 Jun 2019 12:11:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:60794 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731243AbfFMIng (ORCPT ); Thu, 13 Jun 2019 04:43:36 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3034321743; Thu, 13 Jun 2019 08:43:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560415415; bh=Y1WnJruasGRm3U9AQ0OHPrzS3NNHvnFoLXqzcfF6xUc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qkjH+IubBh9ctBlt0I9eYgoUO5stz5jKwN9idzd6n9JkOJn+xca6P+u+OOs4y8PlY VIvEWQ6g/XcEgoHFhajD+8AajwI8aHH7IB9W5IQpJCWptgkVhf1JBj+2us0T9vJIiV EE7110csV9G40ye2jgtSrvn9VIi3a0SEDds+Iz6Y= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eddie Horng , Amir Goldstein , Miklos Szeredi Subject: [PATCH 4.19 117/118] ovl: support stacked SEEK_HOLE/SEEK_DATA Date: Thu, 13 Jun 2019 10:34:15 +0200 Message-Id: <20190613075651.140948053@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190613075643.642092651@linuxfoundation.org> References: <20190613075643.642092651@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Amir Goldstein commit 9e46b840c7053b5f7a245e98cd239b60d189a96c upstream. Overlay file f_pos is the master copy that is preserved through copy up and modified on read/write, but only real fs knows how to SEEK_HOLE/SEEK_DATA and real fs may impose limitations that are more strict than ->s_maxbytes for specific files, so we use the real file to perform seeks. We do not call real fs for SEEK_CUR:0 query and for SEEK_SET:0 requests. Fixes: d1d04ef8572b ("ovl: stack file ops") Reported-by: Eddie Horng Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman --- fs/overlayfs/file.c | 44 ++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 40 insertions(+), 4 deletions(-) --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -146,11 +146,47 @@ static int ovl_release(struct inode *ino static loff_t ovl_llseek(struct file *file, loff_t offset, int whence) { - struct inode *realinode = ovl_inode_real(file_inode(file)); + struct inode *inode = file_inode(file); + struct fd real; + const struct cred *old_cred; + ssize_t ret; - return generic_file_llseek_size(file, offset, whence, - realinode->i_sb->s_maxbytes, - i_size_read(realinode)); + /* + * The two special cases below do not need to involve real fs, + * so we can optimizing concurrent callers. + */ + if (offset == 0) { + if (whence == SEEK_CUR) + return file->f_pos; + + if (whence == SEEK_SET) + return vfs_setpos(file, 0, 0); + } + + ret = ovl_real_fdget(file, &real); + if (ret) + return ret; + + /* + * Overlay file f_pos is the master copy that is preserved + * through copy up and modified on read/write, but only real + * fs knows how to SEEK_HOLE/SEEK_DATA and real fs may impose + * limitations that are more strict than ->s_maxbytes for specific + * files, so we use the real file to perform seeks. + */ + inode_lock(inode); + real.file->f_pos = file->f_pos; + + old_cred = ovl_override_creds(inode->i_sb); + ret = vfs_llseek(real.file, offset, whence); + revert_creds(old_cred); + + file->f_pos = real.file->f_pos; + inode_unlock(inode); + + fdput(real); + + return ret; } static void ovl_file_accessed(struct file *file)