Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933614AbcDMDCF (ORCPT ); Tue, 12 Apr 2016 23:02:05 -0400 Received: from mga03.intel.com ([134.134.136.65]:11711 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933165AbcDMDCD (ORCPT ); Tue, 12 Apr 2016 23:02:03 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,477,1455004800"; d="scan'208";a="84106998" Date: Tue, 12 Apr 2016 23:01:56 -0400 From: Matthew Wilcox To: Toshi Kani Cc: akpm@linux-foundation.org, dan.j.williams@intel.com, linux-nvdimm@ml01.01.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Ts'o" , Andreas Dilger , Jan Kara , Ross Zwisler , linux-ext4@vger.kernel.org Subject: Re: [PATCH v2 2/5] ext4: call dax_get_unmapped_area() for DAX pmd mappings Message-ID: <20160413030156.GN2781@linux.intel.com> References: <1460493572-31667-1-git-send-email-toshi.kani@hpe.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1460493572-31667-1-git-send-email-toshi.kani@hpe.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1094 Lines: 31 On Tue, Apr 12, 2016 at 02:39:29PM -0600, Toshi Kani wrote: > To support DAX pmd mappings with unmodified applications, > filesystems need to align an mmap address by the pmd size. > @@ -708,6 +708,9 @@ const struct file_operations ext4_file_operations = { > .open = ext4_file_open, > .release = ext4_release_file, > .fsync = ext4_sync_file, > +#ifdef CONFIG_FS_DAX > + .get_unmapped_area = dax_get_unmapped_area, > +#endif > .splice_read = generic_file_splice_read, > .splice_write = iter_file_splice_write, > .fallocate = ext4_fallocate, Could you do something like: #ifdef CONFIG_FS_DAX struct page *read_dax_sector(struct block_device *bdev, sector_t n); +unsigned long dax_get_unmapped_area(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, unsigned long flags); #else static inline struct page *read_dax_sector(struct block_device *bdev, sector_t n) { return ERR_PTR(-ENXIO); } +#define dax_get_unmapped_area NULL #endif in patch 1/5. Then there's no need for the ifdefs in each filesystem.