From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753316AbdF2SbG (ORCPT ); Thu, 29 Jun 2017 14:31:06 -0400 Received: from fieldses.org ([173.255.197.46]:51016 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753234AbdF2Saz (ORCPT ); Thu, 29 Jun 2017 14:30:55 -0400 Date: Thu, 29 Jun 2017 14:30:53 -0400 From: "J. Bruce Fields" To: "Darrick J. Wong" Cc: William Koh , Andreas Dilger , "Theodore Ts'o" , linux-ext4 , lkml , Kernel Team , linux-fsdevel , Trond Myklebust , xfs Subject: Re: [PATCH] fs: ext4: inode->i_generation not assigned 0. Message-ID: <20170629183053.GA4178@fieldses.org> References: <20A40B3C-E179-432B-B56F-BDAAF0CD2E1F@dilger.ca> <7CD38230-D961-428F-B2E9-2C0E28CAF442@fb.com> <20170629045940.GB5865@birch.djwong.org> <20170629143551.GB1651@fieldses.org> <20170629172528.GA5869@birch.djwong.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170629172528.GA5869@birch.djwong.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 29, 2017 at 10:25:28AM -0700, Darrick J. Wong wrote: > Was there ever a version of NFS (or more generally callers of the > exportfs code) that couldn't deal with i_generation in the file handle, > and therefore we invented this generation hack to work around the loss > of the generation information? > > There's a comment in xfs_fs_encode_fh about not supporting 64bit inodes > with subtree_check (which seems to require one ino/gen pair for the file > and a second pair for the file's parent) on NFSv2 because v2 doesn't > provide enough space for all the file handle information, but that's the > furthest I got with lazy-mining the git history. :) There's a comment in fs/ext4/super.c:ext4_nfs_get_inode * Currently we don't know the generation for parent directory, so * a generation of 0 means "accept any" But I don't see that used. It was used once upon a time; I see it actually used in old 2.5 code in nfsd_get_dentry. Hm. --b.