Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752659AbdFNXRz (ORCPT ); Wed, 14 Jun 2017 19:17:55 -0400 Received: from mga04.intel.com ([192.55.52.120]:26429 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752121AbdFNXRy (ORCPT ); Wed, 14 Jun 2017 19:17:54 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.39,341,1493708400"; d="scan'208";a="868072016" Subject: [PATCH v4 13/14] libnvdimm, pmem: gate cache management on QUEUE_FLAG_WC in pmem_dax_flush() From: Dan Williams To: linux-nvdimm@lists.01.org Cc: Jan Kara , Matthew Wilcox , x86@kernel.org, linux-kernel@vger.kernel.org, Jeff Moyer , linux-fsdevel@vger.kernel.org, Ross Zwisler , Christoph Hellwig Date: Wed, 14 Jun 2017 16:11:26 -0700 Message-ID: <149748185051.10107.3746460181917620940.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <149703989611.20620.6907872165215640212.stgit@dwillia2-desk3.amr.corp.intel.com> References: <149703989611.20620.6907872165215640212.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.17.1-9-g687f MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1619 Lines: 44 Some platforms arrange for cpu caches to be flushed on power-fail. On those platforms there is no requirement that the kernel track and flush potentially dirty cache lines. Given that we still insert entries into the radix for locking purposes this patch only disables the cache flush loop, not the dirty tracking. Userspace can override the default cache setting via the block device queue "write_cache" attribute in sysfs. Cc: Jeff Moyer Cc: Christoph Hellwig Cc: Matthew Wilcox Cc: Ross Zwisler Suggested-by: Jan Kara Signed-off-by: Dan Williams --- Changes since v3: * move the check of QUEUE_FLAG_WC into the pmem driver directly (Jan) drivers/nvdimm/pmem.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c index 06f6c27ec1e9..49938b246a7b 100644 --- a/drivers/nvdimm/pmem.c +++ b/drivers/nvdimm/pmem.c @@ -244,7 +244,16 @@ static size_t pmem_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, static void pmem_dax_flush(struct dax_device *dax_dev, pgoff_t pgoff, void *addr, size_t size) { - arch_wb_cache_pmem(addr, size); + struct pmem_device *pmem = dax_get_private(dax_dev); + struct gendisk *disk = pmem->disk; + struct request_queue *q = disk->queue; + + /* + * Only perform cache management when the queue has caching + * enabled. + */ + if (test_bit(QUEUE_FLAG_WC, &q->queue_flags)) + arch_wb_cache_pmem(addr, size); } static const struct dax_operations pmem_dax_ops = {