From patchwork Mon Apr 18 21:35:38 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Kara X-Patchwork-Id: 611906 X-Patchwork-Delegate: tytso@mit.edu Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3qphKx4KSRz9sXR for ; Tue, 19 Apr 2016 07:36:37 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752698AbcDRVge (ORCPT ); Mon, 18 Apr 2016 17:36:34 -0400 Received: from mx2.suse.de ([195.135.220.15]:33791 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752172AbcDRVf4 (ORCPT ); Mon, 18 Apr 2016 17:35:56 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id AF4C5ACEF; Mon, 18 Apr 2016 21:35:51 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 74C321E096A; Mon, 18 Apr 2016 23:35:46 +0200 (CEST) From: Jan Kara To: linux-fsdevel@vger.kernel.org Cc: linux-ext4@vger.kernel.org, linux-mm@kvack.org, Ross Zwisler , Dan Williams , linux-nvdimm@lists.01.org, Matthew Wilcox , Jan Kara Subject: [PATCH 15/18] dax: Allow DAX code to replace exceptional entries Date: Mon, 18 Apr 2016 23:35:38 +0200 Message-Id: <1461015341-20153-16-git-send-email-jack@suse.cz> X-Mailer: git-send-email 2.6.6 In-Reply-To: <1461015341-20153-1-git-send-email-jack@suse.cz> References: <1461015341-20153-1-git-send-email-jack@suse.cz> Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org Currently we forbid page_cache_tree_insert() to replace exceptional radix tree entries for DAX inodes. However to make DAX faults race free we will lock radix tree entries and when hole is created, we need to replace such locked radix tree entry with a hole page. So modify page_cache_tree_insert() to allow that. Signed-off-by: Jan Kara Reviewed-by: Ross Zwisler --- include/linux/dax.h | 1 + mm/filemap.c | 18 +++++++++++------- 2 files changed, 12 insertions(+), 7 deletions(-) diff --git a/include/linux/dax.h b/include/linux/dax.h index bef5c44f71b3..fd4aeae65ed7 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -3,6 +3,7 @@ #include #include +#include #include /* We use lowest available exceptional entry bit for locking */ diff --git a/mm/filemap.c b/mm/filemap.c index f2479af09da9..3effd5c8f2f6 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -597,14 +597,18 @@ static int page_cache_tree_insert(struct address_space *mapping, if (!radix_tree_exceptional_entry(p)) return -EEXIST; - if (WARN_ON(dax_mapping(mapping))) - return -EINVAL; - - if (shadowp) - *shadowp = p; mapping->nrexceptional--; - if (node) - workingset_node_shadows_dec(node); + if (!dax_mapping(mapping)) { + if (shadowp) + *shadowp = p; + if (node) + workingset_node_shadows_dec(node); + } else { + /* DAX can replace empty locked entry with a hole */ + WARN_ON_ONCE(p != + (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | + RADIX_DAX_ENTRY_LOCK)); + } } radix_tree_replace_slot(slot, page); mapping->nrpages++;