From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E56801EEA55; Tue, 26 Aug 2025 13:54:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756216492; cv=none; b=Kf6EqJcf9umQw6nBvxm+6KA5OcZajQWdksL6y3CUrxd6R7dB8QTIXFQ/ED7EJCY/3IEfrjVLj+Ri+egaB8+KZUaNeDsY+FO3iuoA/jNlXFi5T3JRrAgKxTsyDjKo+cy+FEvbcZf0V+ydr/nIDi7nNl5ZrRi7XGyV1JZkOmgVnwE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756216492; c=relaxed/simple; bh=L8Ng7aNo0pGzGnKux3FlRX1Xj35IJi1HRTbmMPkQ1ZU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TsLMHu/mzgi5QIeIoczbds2EbNfwci/P+VAdd2DpfxqEuf9y2L8MiheSmm6LocqXxszXvSFDZ1W05t1WC21yKK9cn54KCj9DGSy227qaEd+xe5AypfqBnoykYh8iU7rfuwRdUg1TliKpLq2yyQPO+zkDxYRSuqmTUJSY6VDA6Q4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=u5ryBeVT; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="u5ryBeVT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6F1EBC4CEF1; Tue, 26 Aug 2025 13:54:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1756216491; bh=L8Ng7aNo0pGzGnKux3FlRX1Xj35IJi1HRTbmMPkQ1ZU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=u5ryBeVTo+x0spz4Bt93gaGsFhmTBq7s80esvYS5pfE0onOoHkRJG1ORyj1dwmIbs N1HDPPQ9Ry0agkAZhtEImHpR2Ex8wEMzu8leT0ZHVGM0C5csv7MvEd4I/FCRgfE1a4 ZB/mkaaGB393JeuXlBeFRjGJpt1o3JnUyzdEcT+8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sergey Bashirov , Christoph Hellwig , Trond Myklebust , Sasha Levin Subject: [PATCH 5.15 430/644] pNFS: Fix stripe mapping in block/scsi layout Date: Tue, 26 Aug 2025 13:08:41 +0200 Message-ID: <20250826110957.117791169@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250826110946.507083938@linuxfoundation.org> References: <20250826110946.507083938@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sergey Bashirov [ Upstream commit 81438498a285759f31e843ac4800f82a5ce6521f ] Because of integer division, we need to carefully calculate the disk offset. Consider the example below for a stripe of 6 volumes, a chunk size of 4096, and an offset of 70000. chunk = div_u64(offset, dev->chunk_size) = 70000 / 4096 = 17 offset = chunk * dev->chunk_size = 17 * 4096 = 69632 disk_offset_wrong = div_u64(offset, dev->nr_children) = 69632 / 6 = 11605 disk_chunk = div_u64(chunk, dev->nr_children) = 17 / 6 = 2 disk_offset = disk_chunk * dev->chunk_size = 2 * 4096 = 8192 Signed-off-by: Sergey Bashirov Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20250701122341.199112-1-sergeybashirov@gmail.com Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin --- fs/nfs/blocklayout/dev.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/nfs/blocklayout/dev.c b/fs/nfs/blocklayout/dev.c index 16412d6636e8..4e176d7d704d 100644 --- a/fs/nfs/blocklayout/dev.c +++ b/fs/nfs/blocklayout/dev.c @@ -199,10 +199,11 @@ static bool bl_map_stripe(struct pnfs_block_dev *dev, u64 offset, struct pnfs_block_dev *child; u64 chunk; u32 chunk_idx; + u64 disk_chunk; u64 disk_offset; chunk = div_u64(offset, dev->chunk_size); - div_u64_rem(chunk, dev->nr_children, &chunk_idx); + disk_chunk = div_u64_rem(chunk, dev->nr_children, &chunk_idx); if (chunk_idx >= dev->nr_children) { dprintk("%s: invalid chunk idx %d (%lld/%lld)\n", @@ -215,7 +216,7 @@ static bool bl_map_stripe(struct pnfs_block_dev *dev, u64 offset, offset = chunk * dev->chunk_size; /* disk offset of the stripe */ - disk_offset = div_u64(offset, dev->nr_children); + disk_offset = disk_chunk * dev->chunk_size; child = &dev->children[chunk_idx]; child->map(child, disk_offset, map); -- 2.39.5