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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 6A157C47247 for ; Thu, 7 May 2020 07:53:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 494D2207DD for ; Thu, 7 May 2020 07:53:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726267AbgEGHxq (ORCPT ); Thu, 7 May 2020 03:53:46 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:3834 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725862AbgEGHxq (ORCPT ); Thu, 7 May 2020 03:53:46 -0400 Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 1481E6579506A334BFF2; Thu, 7 May 2020 15:53:44 +0800 (CST) Received: from [127.0.0.1] (10.67.102.197) by DGGEMS401-HUB.china.huawei.com (10.3.19.201) with Microsoft SMTP Server id 14.3.487.0; Thu, 7 May 2020 15:53:38 +0800 Subject: ping; [PATCH v4] mtd: clear cache_state to avoid writing to bad blocks repeatedly To: , , CC: , , , , , References: <1585618319-119741-1-git-send-email-nixiaoming@huawei.com> From: Xiaoming Ni Message-ID: <528b61f3-bddb-d508-8f18-37cebec9e5eb@huawei.com> Date: Thu, 7 May 2020 15:53:32 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: <1585618319-119741-1-git-send-email-nixiaoming@huawei.com> Content-Type: text/plain; charset="gbk"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.102.197] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ping On 2020/3/31 9:31, Xiaoming Ni wrote: > The function call process is as follows: > mtd_blktrans_work() > while (1) > do_blktrans_request() > mtdblock_writesect() > do_cached_write() > write_cached_data() /*if cache_state is STATE_DIRTY*/ > erase_write() > > write_cached_data() returns failure without modifying cache_state > and cache_offset. So when do_cached_write() is called again, > write_cached_data() will be called again to perform erase_write() > on the same cache_offset. > > But if this cache_offset points to a bad block, erase_write() will > always return -EIO. Writing to this mtdblk is equivalent to losing > the current data, and repeatedly writing to the bad block. > > Repeatedly writing a bad block has no real benefits, > but brings some negative effects: > 1 Lost subsequent data > 2 Loss of flash device life > 3 erase_write() bad blocks are very time-consuming. For example: > the function do_erase_oneblock() in chips/cfi_cmdset_0020.c or > chips/cfi_cmdset_0002.c may take more than 20 seconds to return > > Therefore, when erase_write() returns -EIO in write_cached_data(), > clear cache_state to avoid writing to bad blocks repeatedly. > > Signed-off-by: Xiaoming Ni > Reviewed-by: Miquel Raynal > --- > drivers/mtd/mtdblock.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/drivers/mtd/mtdblock.c b/drivers/mtd/mtdblock.c > index 078e0f6..32e52d8 100644 > --- a/drivers/mtd/mtdblock.c > +++ b/drivers/mtd/mtdblock.c > @@ -89,8 +89,6 @@ static int write_cached_data (struct mtdblk_dev *mtdblk) > > ret = erase_write (mtd, mtdblk->cache_offset, > mtdblk->cache_size, mtdblk->cache_data); > - if (ret) > - return ret; > > /* > * Here we could arguably set the cache state to STATE_CLEAN. > @@ -98,9 +96,14 @@ static int write_cached_data (struct mtdblk_dev *mtdblk) > * be notified if this content is altered on the flash by other > * means. Let's declare it empty and leave buffering tasks to > * the buffer cache instead. > + * > + * If this cache_offset points to a bad block, data cannot be > + * written to the device. Clear cache_state to avoid writing to > + * bad blocks repeatedly. > */ > - mtdblk->cache_state = STATE_EMPTY; > - return 0; > + if (ret == 0 || ret == -EIO) > + mtdblk->cache_state = STATE_EMPTY; > + return ret; > } > > >