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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 14BE7C38BE0 for ; Mon, 24 Feb 2020 19:57:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EA85820CC7 for ; Mon, 24 Feb 2020 19:57:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727304AbgBXT5i (ORCPT ); Mon, 24 Feb 2020 14:57:38 -0500 Received: from mga05.intel.com ([192.55.52.43]:14001 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726593AbgBXT5h (ORCPT ); Mon, 24 Feb 2020 14:57:37 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Feb 2020 11:57:37 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,481,1574150400"; d="scan'208";a="255695319" Received: from iweiny-desk2.sc.intel.com ([10.3.52.157]) by orsmga002.jf.intel.com with ESMTP; 24 Feb 2020 11:57:36 -0800 Date: Mon, 24 Feb 2020 11:57:36 -0800 From: Ira Weiny To: Dave Chinner 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: <20200224195735.GA11565@iweiny-DESK2.sc.intel.com> References: <20200221004134.30599-1-ira.weiny@intel.com> <20200221004134.30599-10-ira.weiny@intel.com> <20200224003455.GY10776@dread.disaster.area> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200224003455.GY10776@dread.disaster.area> User-Agent: Mutt/1.11.1 (2018-12-01) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Feb 24, 2020 at 11:34:55AM +1100, Dave Chinner wrote: > On Thu, Feb 20, 2020 at 04:41:30PM -0800, ira.weiny@intel.com wrote: > > From: Ira Weiny > > [snip] > > > > 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. I know it seems overkill but if we don't do this we need to code a flag to be returned from xfs_ioctl_setattr_dax_invalidate(). This flag is then used in xfs_ioctl_setattr_get_trans() to create the transaction log item which can then be properly used to unlock the lock in xfs_inode_item_release() I don't know of a cleaner way to communicate to xfs_inode_item_release() to unlock i_aops_sem after the transaction is complete. Ira > > Cheers, > > Dave. > -- > Dave Chinner > david@fromorbit.com