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=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 A0489C432C0 for ; Wed, 20 Nov 2019 12:51:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 787E9224F3 for ; Wed, 20 Nov 2019 12:51:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729860AbfKTMvS (ORCPT ); Wed, 20 Nov 2019 07:51:18 -0500 Received: from mx2.suse.de ([195.135.220.15]:38560 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729820AbfKTMvS (ORCPT ); Wed, 20 Nov 2019 07:51:18 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id A57F9B3B6; Wed, 20 Nov 2019 12:51:16 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 4E5B81E484C; Wed, 20 Nov 2019 13:51:16 +0100 (CET) Date: Wed, 20 Nov 2019 13:51:16 +0100 From: Jan Kara To: Ritesh Harjani Cc: jack@suse.cz, tytso@mit.edu, linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, mbobrowski@mbobrowski.org Subject: Re: [RFCv3 1/4] ext4: fix ext4_dax_read/write inode locking sequence for IOCB_NOWAIT Message-ID: <20191120125116.GB9509@quack2.suse.cz> References: <20191120050024.11161-1-riteshh@linux.ibm.com> <20191120050024.11161-2-riteshh@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191120050024.11161-2-riteshh@linux.ibm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed 20-11-19 10:30:21, Ritesh Harjani wrote: > Apparently our current rwsem code doesn't like doing the trylock, then > lock for real scheme. So change our dax read/write methods to just do the > trylock for the RWF_NOWAIT case. > This seems to fix AIM7 regression in some scalable filesystems upto ~25% > in some cases. Claimed in commit 942491c9e6d6 ("xfs: fix AIM7 regression") > > Signed-off-by: Ritesh Harjani Looks good to me. You can add: Reviewed-by: Jan Kara Honza > --- > fs/ext4/file.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/fs/ext4/file.c b/fs/ext4/file.c > index 6a7293a5cda2..977ac58dc718 100644 > --- a/fs/ext4/file.c > +++ b/fs/ext4/file.c > @@ -88,9 +88,10 @@ static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to) > struct inode *inode = file_inode(iocb->ki_filp); > ssize_t ret; > > - if (!inode_trylock_shared(inode)) { > - if (iocb->ki_flags & IOCB_NOWAIT) > + if (iocb->ki_flags & IOCB_NOWAIT) { > + if (!inode_trylock_shared(inode)) > return -EAGAIN; > + } else { > inode_lock_shared(inode); > } > /* > @@ -487,9 +488,10 @@ ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from) > bool extend = false; > struct inode *inode = file_inode(iocb->ki_filp); > > - if (!inode_trylock(inode)) { > - if (iocb->ki_flags & IOCB_NOWAIT) > + if (iocb->ki_flags & IOCB_NOWAIT) { > + if (!inode_trylock(inode)) > return -EAGAIN; > + } else { > inode_lock(inode); > } > > -- > 2.21.0 > -- Jan Kara SUSE Labs, CR