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, USER_AGENT_SANE_2 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 F3937C43331 for ; Mon, 30 Mar 2020 07:53:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CD8872073B for ; Mon, 30 Mar 2020 07:53:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729565AbgC3Hxq convert rfc822-to-8bit (ORCPT ); Mon, 30 Mar 2020 03:53:46 -0400 Received: from relay12.mail.gandi.net ([217.70.178.232]:43793 "EHLO relay12.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729413AbgC3Hxq (ORCPT ); Mon, 30 Mar 2020 03:53:46 -0400 Received: from xps13 (unknown [91.224.148.103]) (Authenticated sender: miquel.raynal@bootlin.com) by relay12.mail.gandi.net (Postfix) with ESMTPSA id E473F200009; Mon, 30 Mar 2020 07:53:42 +0000 (UTC) Date: Mon, 30 Mar 2020 09:53:41 +0200 From: Miquel Raynal To: Xiaoming Ni Cc: , , , , , , , Subject: Re: [PATCH] mtd:clear cache_state to avoid writing to bad clocks repeatedly Message-ID: <20200330095341.284048c3@xps13> In-Reply-To: <1585400477-65705-1-git-send-email-nixiaoming@huawei.com> References: <1585400477-65705-1-git-send-email-nixiaoming@huawei.com> Organization: Bootlin X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-pc-linux-gnu) 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 Hi Xiaoming, Xiaoming Ni wrote on Sat, 28 Mar 2020 21:01:17 +0800: > 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 clocks repeatedly. blocks > > Signed-off-by: Xiaoming Ni > --- > 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..98c25d6 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 Can you start your sentences with a capital letter please? * If > + * data cannot be written to the device. > + * clear cache_state to avoid writing to bad clocks repeatedly * Clear And also please break your lines à 80, not 70. > */ > - mtdblk->cache_state = STATE_EMPTY; > - return 0; > + if (ret == 0 || ret == -EIO) > + mtdblk->cache_state = STATE_EMPTY; > + return ret; > } > > Otherwise looks good to me. With the above addressed: Reviewed-by: Miquel Raynal Thanks, Miquèl