From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935310AbdEWPKh (ORCPT ); Tue, 23 May 2017 11:10:37 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:36697 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758683AbdEWPKe (ORCPT ); Tue, 23 May 2017 11:10:34 -0400 Authentication-Results: infradead.org; dkim=none (message not signed) header.d=none;infradead.org; dmarc=none action=none header.from=fb.com; Date: Tue, 23 May 2017 08:09:48 -0700 From: Shaohua Li To: Christoph Hellwig CC: , , , , Subject: Re: [PATCH 1/5] kernfs: implement i_generation Message-ID: <20170523150946.GA6123@smirco-mbp.DHCP.thefacebook.com> References: <1840aeeff2e745d223b01514a433b4b7f20040a6.1495490800.git.shli@fb.com> <20170523074112.GD29525@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20170523074112.GD29525@infradead.org> User-Agent: Mutt/1.8.0 (2017-02-23) X-Originating-IP: [2620:10d:c090:180::46f1] X-ClientProxiedBy: BN6PR05CA0018.namprd05.prod.outlook.com (10.174.92.159) To BN6PR15MB1635.namprd15.prod.outlook.com (10.175.131.9) X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN6PR15MB1635: X-MS-Office365-Filtering-Correlation-Id: 725ba19e-544c-46af-d104-08d4a1edc6cc X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(22001)(201703131423075)(201703031133081);SRVR:BN6PR15MB1635; 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This is required to implement exportfs > > operations. > > > > Signed-off-by: Shaohua Li > > --- > > fs/kernfs/dir.c | 2 ++ > > fs/kernfs/inode.c | 1 + > > include/linux/kernfs.h | 2 ++ > > 3 files changed, 5 insertions(+) > > > > diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c > > index db5900aaa..09d093e 100644 > > --- a/fs/kernfs/dir.c > > +++ b/fs/kernfs/dir.c > > @@ -634,6 +634,7 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root, > > if (ret < 0) > > goto err_out2; > > kn->ino = ret; > > + kn->generation = atomic_inc_return(&root->next_generation); > > i_generation is only supposed to be valid on a per-inode basis, so this > global counter seems really odd. What's the difference between per-inode or per-super? The i_generation doesn't need to be consecutive for an inode. I checked other fs, a lot of filesystems implement i_generation in this way, for example, f2fs, ext4. Thanks, Shaohua