From mboxrd@z Thu Jan 1 00:00:00 1970 From: Miklos Szeredi Subject: Re: [PATCH v3 5/5] ovl: consistent st_ino/d_ino Date: Wed, 21 Jun 2017 10:53:02 +0200 Message-ID: References: <1496307779-2766-1-git-send-email-amir73il@gmail.com> <1496307779-2766-6-git-send-email-amir73il@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: Received: from mail-ot0-f196.google.com ([74.125.82.196]:34552 "EHLO mail-ot0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752704AbdFUIxE (ORCPT ); Wed, 21 Jun 2017 04:53:04 -0400 Received: by mail-ot0-f196.google.com with SMTP id p48so18458247otc.1 for ; Wed, 21 Jun 2017 01:53:03 -0700 (PDT) In-Reply-To: Sender: linux-unionfs-owner@vger.kernel.org List-Id: linux-unionfs@vger.kernel.org To: Amir Goldstein Cc: Chandan Rajendra , "linux-unionfs@vger.kernel.org" On Wed, Jun 21, 2017 at 10:49 AM, Amir Goldstein wrote: > On Wed, Jun 21, 2017 at 11:45 AM, Miklos Szeredi wrote: >> On Wed, Jun 21, 2017 at 10:38 AM, Miklos Szeredi wrote: >>> On Wed, Jun 21, 2017 at 10:20 AM, Miklos Szeredi wrote: >>> >>>> Right. The problem is when dir becomes impure due to rename between >>>> two getdents(2) calls. We can't call ovl_dir_reset() because the >>>> offset is not zero. We could do a "cache with head cut off" starting >>>> from the current offset in the dir and finish with that. Yeah, it's >>>> probably less complexity than trying to intercept the actor... >>> >>> On the other hand, we'll need to accommodate the native directory >>> indexing (i.e. seekdir(3) hell) in the cache, which is going to add to >>> complexity. Ugh. >> >> Another idea: we are allowed to omit directory entries added after >> the opendir/rewinddir. So if there was a simple way to filter out >> newly added entries which have origin then we are fine. >> > > Then how about this: implement an actor that ONLY looks in > overlay dcache for the entries. > If entry is in dcache then can take inode number from overlay > inode. > If entry is not in dcache AND the file was just moved into dir > (quite unlinkely) then write off d_ino as a transient inconsistency. Note: in theory the "just moved into dir" can be two weeks before. In practice it's unlikely that two calls of getdents(2) will be so far apart in time. Still, this feels a bit too hacky. Thanks, Miklos