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=-8.2 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 CAE49C35673 for ; Mon, 24 Feb 2020 00:35:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A283720675 for ; Mon, 24 Feb 2020 00:35:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727197AbgBXAfD (ORCPT ); Sun, 23 Feb 2020 19:35:03 -0500 Received: from mail105.syd.optusnet.com.au ([211.29.132.249]:43679 "EHLO mail105.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727151AbgBXAfD (ORCPT ); Sun, 23 Feb 2020 19:35:03 -0500 Received: from dread.disaster.area (pa49-195-185-106.pa.nsw.optusnet.com.au [49.195.185.106]) by mail105.syd.optusnet.com.au (Postfix) with ESMTPS id B52CD3A211E; Mon, 24 Feb 2020 11:34:57 +1100 (AEDT) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1j61i4-0004s8-0Y; Mon, 24 Feb 2020 11:34:56 +1100 Date: Mon, 24 Feb 2020 11:34:55 +1100 From: Dave Chinner To: ira.weiny@intel.com Cc: linux-kernel@vger.kernel.org, Alexander Viro , "Darrick J. Wong" , Dan Williams , 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 V4 09/13] fs/xfs: Add write aops lock to xfs layer Message-ID: <20200224003455.GY10776@dread.disaster.area> References: <20200221004134.30599-1-ira.weiny@intel.com> <20200221004134.30599-10-ira.weiny@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200221004134.30599-10-ira.weiny@intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.3 cv=LYdCFQXi c=1 sm=1 tr=0 a=bkRQb8bsQZKWSSj4M57YXw==:117 a=bkRQb8bsQZKWSSj4M57YXw==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=kj9zAlcOel0A:10 a=l697ptgUJYAA:10 a=QyXUC8HyAAAA:8 a=7-415B0cAAAA:8 a=jzfXMxHasCwLGlr9pT0A:9 a=CjuIK1q_8ugA:10 a=biEYGPWJfzWAr4FL6Ov7:22 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 20, 2020 at 04:41:30PM -0800, ira.weiny@intel.com wrote: > From: Ira Weiny > > XFS requires the use of the aops of an inode to quiesced prior to > changing it to/from the DAX aops vector. > > Take the aops write lock while changing DAX state. > > We define a new XFS_DAX_EXCL lock type to carry the lock through to > transaction completion. > > Signed-off-by: Ira Weiny > > --- > Changes from v3: > Change locking function names to reflect changes in previous > patches. > > Changes from V2: > Change name of patch (WAS: fs/xfs: Add lock/unlock state to xfs) > Remove the xfs specific lock and move to the vfs layer. > We still use XFS_LOCK_DAX_EXCL to be able to pass this > flag through to the transaction code. But we no longer > have a lock specific to xfs. This removes a lot of code > from the XFS layer, preps us for using this in ext4, and > is actually more straight forward now that all the > locking requirements are better known. > > Fix locking order comment > Rework for new 'state' names > (Other comments on the previous patch are not applicable with > new patch as much of the code was removed in favor of the vfs > level lock) > --- > fs/xfs/xfs_inode.c | 22 ++++++++++++++++++++-- > fs/xfs/xfs_inode.h | 7 +++++-- > 2 files changed, 25 insertions(+), 4 deletions(-) > > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c > index 35df324875db..5b014c428f0f 100644 > --- a/fs/xfs/xfs_inode.c > +++ b/fs/xfs/xfs_inode.c > @@ -142,12 +142,12 @@ xfs_ilock_attr_map_shared( > * > * Basic locking order: > * > - * i_rwsem -> i_mmap_lock -> page_lock -> i_ilock > + * s_dax_sem -> i_rwsem -> i_mmap_lock -> page_lock -> i_ilock > * > * mmap_sem locking order: > * > * i_rwsem -> page lock -> mmap_sem > - * mmap_sem -> i_mmap_lock -> page_lock > + * s_dax_sem -> mmap_sem -> i_mmap_lock -> page_lock > * > * The difference in mmap_sem locking order mean that we cannot hold the > * i_mmap_lock over syscall based read(2)/write(2) based IO. These IO paths can > @@ -182,6 +182,9 @@ xfs_ilock( > (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)); > ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_SUBCLASS_MASK)) == 0); > > + if (lock_flags & XFS_DAX_EXCL) > + inode_aops_down_write(VFS_I(ip)); I largely don't see the point of adding this to xfs_ilock/iunlock. It's only got one caller, so I don't see much point in adding it to an interface that has over a hundred other call sites that don't need or use this lock. just open code it where it is needed in the ioctl code. Cheers, Dave. -- Dave Chinner david@fromorbit.com