From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6EA7BCA9EA0 for ; Tue, 22 Oct 2019 16:51:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4C6982084B for ; Tue, 22 Oct 2019 16:51:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732881AbfJVQvb (ORCPT ); Tue, 22 Oct 2019 12:51:31 -0400 Received: from mga02.intel.com ([134.134.136.20]:31181 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727885AbfJVQvb (ORCPT ); Tue, 22 Oct 2019 12:51:31 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 22 Oct 2019 09:51:29 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,216,1569308400"; d="scan'208";a="201737358" Received: from iweiny-desk2.sc.intel.com ([10.3.52.157]) by orsmga006.jf.intel.com with ESMTP; 22 Oct 2019 09:51:29 -0700 Date: Tue, 22 Oct 2019 09:51:29 -0700 From: Ira Weiny To: Boaz Harrosh Cc: linux-kernel@vger.kernel.org, Alexander Viro , "Darrick J. Wong" , Dan Williams , Dave Chinner , Christoph Hellwig , "Theodore Y. Ts'o" , Jan Kara , linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH 1/5] fs/stat: Define DAX statx attribute Message-ID: <20191022165128.GA5432@iweiny-DESK2.sc.intel.com> References: <20191020155935.12297-1-ira.weiny@intel.com> <20191020155935.12297-2-ira.weiny@intel.com> <119b57ed-2799-c499-00df-50da80d23612@plexistor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <119b57ed-2799-c499-00df-50da80d23612@plexistor.com> User-Agent: Mutt/1.11.1 (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 22, 2019 at 02:32:04PM +0300, Boaz Harrosh wrote: > On 20/10/2019 18:59, ira.weiny@intel.com wrote: > > From: Ira Weiny > > > > In order for users to determine if a file is currently operating in DAX > > mode (effective DAX). Define a statx attribute value and set that > > attribute if the effective DAX flag is set. > > > > To go along with this we propose the following addition to the statx man > > page: > > > > STATX_ATTR_DAX > > > > DAX (cpu direct access) is a file mode that attempts to minimize > > software cache effects for both I/O and memory mappings of this > > file. It requires a capable device, a compatible filesystem > > block size, and filesystem opt-in. It generally assumes all > > accesses are via cpu load / store instructions which can > > minimize overhead for small accesses, but adversely affect cpu > > utilization for large transfers. File I/O is done directly > > to/from user-space buffers. While the DAX property tends to > > result in data being transferred synchronously it does not give > > the guarantees of synchronous I/O that data and necessary > > metadata are transferred. Memory mapped I/O may be performed > > with direct mappings that bypass system memory buffering. Again > > while memory-mapped I/O tends to result in data being > > transferred synchronously it does not guarantee synchronous > > metadata updates. A dax file may optionally support being mapped > > with the MAP_SYNC flag which does allow cpu store operations to > > be considered synchronous modulo cpu cache effects. > > > > Signed-off-by: Ira Weiny > > --- > > fs/stat.c | 3 +++ > > include/uapi/linux/stat.h | 1 + > > 2 files changed, 4 insertions(+) > > > > diff --git a/fs/stat.c b/fs/stat.c > > index c38e4c2e1221..59ca360c1ffb 100644 > > --- a/fs/stat.c > > +++ b/fs/stat.c > > @@ -77,6 +77,9 @@ int vfs_getattr_nosec(const struct path *path, struct kstat *stat, > > if (IS_AUTOMOUNT(inode)) > > stat->attributes |= STATX_ATTR_AUTOMOUNT; > > > > + if (inode->i_flags & S_DAX) > > Is there a reason not to use IS_DAX(inode) ? No, just forgot there was a macro when this was written. Changed. Thanks, Ira > > > + stat->attributes |= STATX_ATTR_DAX; > > + > > if (inode->i_op->getattr) > > return inode->i_op->getattr(path, stat, request_mask, > > query_flags); > > diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h > > index 7b35e98d3c58..5b0962121ef7 100644 > > --- a/include/uapi/linux/stat.h > > +++ b/include/uapi/linux/stat.h > > @@ -169,6 +169,7 @@ struct statx { > > #define STATX_ATTR_ENCRYPTED 0x00000800 /* [I] File requires key to decrypt in fs */ > > > > #define STATX_ATTR_AUTOMOUNT 0x00001000 /* Dir: Automount trigger */ > > +#define STATX_ATTR_DAX 0x00002000 /* [I] File is DAX */ > > > > > > #endif /* _UAPI_LINUX_STAT_H */ > > >