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 79FD1322DC8; Mon, 18 Aug 2025 14:08:38 +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=1755526118; cv=none; b=TqVfsIym7AdVaYUWU7ybhDB/OfpMBtdpNF7CvgoUlLQceqhEzB0tg4SB6qudtq/sV2P7mW83IjK353/FZ/fkuN7U/Xjt1pkAIDeu/6B9NbpM3JLCbg0VnCa/iabtpAsxfXb3v7bprTyq49Hwdg93qJp36B2V2e1SMRBkdjtBTd0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755526118; c=relaxed/simple; bh=2i2wVO4o/GNpC4rQDvnlH09GUGWTveWAHMNVYjpQBCk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Spt4yRKGh06z3O3sHV+O0BPcWXPF26zo0I+1JE5PdrA66nVm/6osoKrzHe/Qe0zdXlMp+tZMyqJLiN5aKkzZlicnT4d8kMg76yUumUvXjsobqUIbdlpi8ky1cEA9BduAdBoh2Cw6cR58qVek/9cOL9+DUgZFg99QWmhfKyJTKbI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=fSPtrNpH; 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="fSPtrNpH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0138BC4CEEB; Mon, 18 Aug 2025 14:08:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755526118; bh=2i2wVO4o/GNpC4rQDvnlH09GUGWTveWAHMNVYjpQBCk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fSPtrNpHeTzSiN6+GcsqKl7ErE8I+RPxcx1DdbnTghXSf/ERWfnBko2JgtxkbIsoA Xj7lxzNKYx4d6UgByvEo9iAf3lPqxN1POEmEdzSrxIeAc8W6qAoELCZhwJW+XYGu1q 2cXLFgQqFLmRu3yKDW4u0zZJ2sSBS4yj9zbPr7ZM= 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 6.16 464/570] pNFS: Fix stripe mapping in block/scsi layout Date: Mon, 18 Aug 2025 14:47:31 +0200 Message-ID: <20250818124523.737808663@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250818124505.781598737@linuxfoundation.org> References: <20250818124505.781598737@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 6.16-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 cab8809f0e0f..44306ac22353 100644 --- a/fs/nfs/blocklayout/dev.c +++ b/fs/nfs/blocklayout/dev.c @@ -257,10 +257,11 @@ 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", @@ -273,7 +274,7 @@ 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