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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 BEDB0C433DB for ; Wed, 23 Dec 2020 16:28:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 83E7C22242 for ; Wed, 23 Dec 2020 16:28:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726047AbgLWQ2W (ORCPT ); Wed, 23 Dec 2020 11:28:22 -0500 Received: from verein.lst.de ([213.95.11.211]:34933 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725807AbgLWQ2W (ORCPT ); Wed, 23 Dec 2020 11:28:22 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 2FC4F67373; Wed, 23 Dec 2020 17:27:38 +0100 (CET) Date: Wed, 23 Dec 2020 17:27:37 +0100 From: Christoph Hellwig To: Minwoo Im Cc: Christoph Hellwig , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, Keith Busch , Jens Axboe , Sagi Grimberg Subject: Re: [RFC] nvme: set block size during namespace validation Message-ID: <20201223162737.GA8688@lst.de> References: <20201223150136.4221-1-minwoo.im.dev@gmail.com> <20201223154904.GA5967@lst.de> <20201223161650.GA13354@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201223161650.GA13354@localhost.localdomain> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Thu, Dec 24, 2020 at 01:16:50AM +0900, Minwoo Im wrote: > Hello, > > On 20-12-23 16:49:04, Christoph Hellwig wrote: > > set_blocksize just sets the block sise used for buffer heads and should > > not be called by the driver. blkdev_get updates the block size, so > > you must already have the fd re-reading the partition table open? > > I'm not entirely sure how we can work around this except by avoiding > > buffer head I/O in the partition reread code. Note that this affects > > all block drivers where the block size could change at runtime. > > Thank you Christoph for your comment on this. > > Agreed. BLKRRPART leads us to block_read_full_page which takes buffer > heads for I/O. > > Yes, __blkdev_get() sets i_blkbits of block device inode via > set_init_blocksize. And Yes again as nvme-cli already opened the block > device fd and requests the BLKRRPART with that fd. Also, __bdev_get() > only updates the i_blkbits(blocksize) in case bdev->bd_openers == 0 which > is the first time to open this block device. > > Then, how about having NVMe driver prevent underflow case for the > request->__data_len is smaller than the logical block size like: Not sure this helps. I think we need to fix this proper and in the block layer. The long term fix is to stop messing with i_blksize at all, but that is going to take very long. I think for now the only thing we can do is to set a flag in the gendisk when the block size changes and then reject all I/O until the next first open that sets the blocksize.