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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id ED4CEC61DDC for ; Sat, 29 Aug 2026 06:26:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type: Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Message-ID:Date :Subject:CC:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=ktiYUYsUp5uCXnvJH/BfqE9fq8l5SXsVdqzLvfHOlV4=; b=lZtaPhuqL8zLFvQljhWXKwB8rM T28skkd2PY6Mje1wl65ppJHj8KZ5PZWR1U4recm9Uni+VTvRuz36PXPhNH8zXE61z++jAv1xcPy7a MMzfVYSq98aM8p3SXZVT9rD9EhLcEczvzcbvZgQUo7iEuKNZF/RnaxSe+5nFOCFXtbs/udRcWJnLI 8M7VuzOQYs8u7dB4Fzn5jbzYFhFj0t8dJbnpd3cQYR63A9rApBohIva6JeFyYnOy0PapPYzesW+bY tqdlRlT7OicSaq7G2UH842K0Hrjn1UDAihcK2C/346OV3CwYxa2CX1GRB3wx141RrEzNtwiuijfj/ 9CxmlgHA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x0CVn-00000006mYU-22Ua; Sat, 29 Aug 2026 06:25:55 +0000 Received: from canpmsgout08.his.huawei.com ([113.46.200.223]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x0CVa-00000006mPj-2Ss9; Sat, 29 Aug 2026 06:25:44 +0000 dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=ktiYUYsUp5uCXnvJH/BfqE9fq8l5SXsVdqzLvfHOlV4=; b=C7JNq/9nW8O1L4+qB8K+5l2GGzD9N3sj5EVi4EnDL5oF6x+3kjr/TdY9xkttUhd/epZ+ev4bJ 5hgEztLJqonv6F5ys20YZ0BjHoNMDdhG8jwXb6tQTPxKCRn3gSjQig20fZertp3RZEGPOPARqMX 1uaVaJBSLupvQPWZ6L7moek= Received: from mail.maildlp.com (unknown [172.19.163.15]) by canpmsgout08.his.huawei.com (SkyGuard) with ESMTPS id 4hX4jJ3V8WzmVXs; Sat, 29 Aug 2026 14:14:44 +0800 (CST) Received: from dggpemr100018.china.huawei.com (unknown [7.185.36.64]) by mail.maildlp.com (Postfix) with ESMTPS id 17D3B40578; Sat, 29 Aug 2026 14:25:32 +0800 (CST) Received: from huawei.com (10.50.85.155) by dggpemr100018.china.huawei.com (7.185.36.64) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.36; Sat, 29 Aug 2026 14:25:31 +0800 From: zhouminqiang To: , , , , , CC: , , , , , , Subject: [PATCH v2 3/7] jffs2: write verify: add byte-by-byte comparison on mismatch Date: Sat, 29 Aug 2026 14:16:53 +0800 Message-ID: <20260829061658.306854-4-zhouminqiang2@huawei.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260829061658.306854-1-zhouminqiang2@huawei.com> References: <20260829061658.306854-1-zhouminqiang2@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.50.85.155] X-ClientProxiedBy: kwepems100001.china.huawei.com (7.221.188.238) To dggpemr100018.china.huawei.com (7.185.36.64) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260828_232543_014792_32FC39F9 X-CRM114-Status: GOOD ( 14.25 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org jffs2_verify_write() uses memcmp() to compare the write buffer against data read back from flash. On mismatch, the current code dumps the entire source and read-back data, which will become impractical once the verify path is extended to NOR flash where a single write can span PAGE_SIZE. Add a byte-by-byte comparison after the memcmp() mismatch path to locate the exact mismatch offset, reporting the first differing offset and dumping up to 128 bytes of both the source and read-back data. memcmp() remains on the hotpath for successful writes, and the byte-by-byte loop only runs when an error is actually detected. Signed-off-by: zhouminqiang --- fs/jffs2/wbuf.c | 46 ++++++++++++++++++++++++++++------------------ 1 file changed, 28 insertions(+), 18 deletions(-) diff --git a/fs/jffs2/wbuf.c b/fs/jffs2/wbuf.c index f10be57c5543..74e169dedab7 100644 --- a/fs/jffs2/wbuf.c +++ b/fs/jffs2/wbuf.c @@ -231,7 +231,7 @@ static int jffs2_verify_write(struct jffs2_sb_info *c, unsigned char *buf, uint32_t ofs) { int ret; - size_t retlen; + size_t retlen, i; char *eccstr; void *verify_buf; @@ -246,10 +246,10 @@ static int jffs2_verify_write(struct jffs2_sb_info *c, unsigned char *buf, if (ret && ret != -EUCLEAN && ret != -EBADMSG) { pr_warn("%s(): Read back of page at %08x failed: %d\n", - __func__, c->wbuf_ofs, ret); + __func__, ofs, ret); goto out_free; } else if (retlen != c->wbuf_pagesize) { - pr_warn("%s(): Read back of page at %08x gave short read: %zd not %d\n", + pr_warn("%s(): Read back of page at %08x gave short read: %zu not %d\n", __func__, ofs, retlen, c->wbuf_pagesize); ret = -EIO; goto out_free; @@ -259,24 +259,34 @@ static int jffs2_verify_write(struct jffs2_sb_info *c, unsigned char *buf, goto out_free; } - if (ret == -EUCLEAN) - eccstr = "corrected"; - else if (ret == -EBADMSG) - eccstr = "correction failed"; - else - eccstr = "OK or unused"; + for (i = 0; i < c->wbuf_pagesize; i++) { + uint8_t c1 = ((uint8_t *)buf)[i]; + uint8_t c2 = ((uint8_t *)verify_buf)[i]; + int dump_len; - pr_warn("Write verify error (ECC %s) at %08x. Wrote:\n", - eccstr, c->wbuf_ofs); - print_hex_dump(KERN_WARNING, "", DUMP_PREFIX_OFFSET, 16, 1, - c->wbuf, c->wbuf_pagesize, 0); + if (c1 == c2) + continue; - pr_warn("Read back:\n"); - print_hex_dump(KERN_WARNING, "", DUMP_PREFIX_OFFSET, 16, 1, - verify_buf, c->wbuf_pagesize, 0); + if (ret == -EUCLEAN) + eccstr = "corrected"; + else if (ret == -EBADMSG) + eccstr = "correction failed"; + else + eccstr = "OK or unused"; - kfree(verify_buf); - return -EIO; + dump_len = min_t(int, 128, c->wbuf_pagesize - i); + pr_warn("Write verify error (ECC %s) at %08x (+%zu/%d). Wrote:\n", + eccstr, ofs, i, c->wbuf_pagesize); + print_hex_dump(KERN_WARNING, "", DUMP_PREFIX_OFFSET, 16, 1, + buf + i, dump_len, 0); + + pr_warn("Read back:\n"); + print_hex_dump(KERN_WARNING, "", DUMP_PREFIX_OFFSET, 16, 1, + verify_buf + i, dump_len, 0); + + ret = -EIO; + goto out_free; + } out_free: kfree(verify_buf); -- 2.52.0