From patchwork Fri May 25 02:55:15 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ross Zwisler X-Patchwork-Id: 10425971 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 7B50A602D8 for ; Fri, 25 May 2018 02:57:37 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6CBFC294DD for ; Fri, 25 May 2018 02:57:37 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5F7B6294DF; Fri, 25 May 2018 02:57:37 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 026AA294CC for ; Fri, 25 May 2018 02:57:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755273AbeEYC42 (ORCPT ); Thu, 24 May 2018 22:56:28 -0400 Received: from mga05.intel.com ([192.55.52.43]:22225 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754385AbeEYCzd (ORCPT ); Thu, 24 May 2018 22:55:33 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 May 2018 19:55:23 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.49,438,1520924400"; d="scan'208";a="42054621" Received: from theros.lm.intel.com ([10.232.112.164]) by fmsmga007.fm.intel.com with ESMTP; 24 May 2018 19:55:23 -0700 From: Ross Zwisler To: Toshi Kani , Mike Snitzer , dm-devel@redhat.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, Ross Zwisler Subject: [PATCH 4/7] dm: prevent DAX mounts if not supported Date: Thu, 24 May 2018 20:55:15 -0600 Message-Id: <20180525025518.11405-5-ross.zwisler@linux.intel.com> X-Mailer: git-send-email 2.14.3 In-Reply-To: <20180525025518.11405-1-ross.zwisler@linux.intel.com> References: <20180525025518.11405-1-ross.zwisler@linux.intel.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently the code in dm_dax_direct_access() only checks whether the target type has a direct_access() operation defined, not whether the underlying block devices all support DAX. This latter property can be seen by looking at whether we set the QUEUE_FLAG_DAX request queue flag when creating the DM device. This is problematic if we have, for example, a dm-linear device made up of a PMEM namespace in fsdax mode followed by a ramdisk from BRD. QUEUE_FLAG_DAX won't be set on the dm-linear device's request queue, but we have a working direct_access() entry point and the first member of the dm-linear set *does* support DAX. This allows the user to create a filesystem on the dm-linear device, and then mount it with DAX. The filesystem's bdev_dax_supported() test will pass because it'll operate on the first member of the dm-linear device, which happens to be a fsdax PMEM namespace. All DAX I/O will then fail to that dm-linear device because the lack of QUEUE_FLAG_DAX prevents fs_dax_get_by_bdev() from working. This means that the struct dax_device isn't ever set in the filesystem, so dax_direct_access() will always return -EOPNOTSUPP. By failing out of dm_dax_direct_access() if QUEUE_FLAG_DAX isn't set we let the filesystem know we don't support DAX at mount time. The filesystem will then silently fall back and remove the dax mount option, causing it to work properly. Signed-off-by: Ross Zwisler Fixes: commit 545ed20e6df6 ("dm: add infrastructure for DAX support") --- drivers/md/dm.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 0a7b0107ca78..9728433362d1 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1050,14 +1050,13 @@ static long dm_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, if (!ti) goto out; - if (!ti->type->direct_access) + if (!blk_queue_dax(md->queue)) goto out; len = max_io_len(sector, ti) / PAGE_SECTORS; if (len < 1) goto out; nr_pages = min(len, nr_pages); - if (ti->type->direct_access) - ret = ti->type->direct_access(ti, pgoff, nr_pages, kaddr, pfn); + ret = ti->type->direct_access(ti, pgoff, nr_pages, kaddr, pfn); out: dm_put_live_table(md, srcu_idx);