Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751927Ab2HTL0u (ORCPT ); Mon, 20 Aug 2012 07:26:50 -0400 Received: from mail-lb0-f174.google.com ([209.85.217.174]:37804 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750791Ab2HTL0s (ORCPT ); Mon, 20 Aug 2012 07:26:48 -0400 MIME-Version: 1.0 Reply-To: sedat.dilek@gmail.com In-Reply-To: <8326.1345459098@jrobl> References: <20120816204440.GA8808@ymail.com> <20120817010519.GA2440@ymail.com> <8326.1345459098@jrobl> Date: Mon, 20 Aug 2012 13:26:46 +0200 Message-ID: Subject: Re: [overlayfs/port] overlayfs: v13 port attempt to kernel 3.5 From: Sedat Dilek To: "J. R. Okajima" Cc: Andrew Watts , Linus Torvalds , linux-fsdevel@vger.kernel.org, LKML , Daniel Baumann Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2166 Lines: 55 On Mon, Aug 20, 2012 at 12:38 PM, J. R. Okajima wrote: > > Sedat Dilek: >> The other part to run a Linux live-system is a "Union FileSystem" - >> this part is missing (speaking of upstream). >> >> Since years AUFS seems to be the choice #1 in a lot of distros to >> workaround the problem. >> NOTE: AUFS was rejected from upstream (to say not accepted). > > Exactly. > The reason was that linux rejects all union-type filesystems but > UnionMount (which is union-type mount). > Later, the development of UnionMount seems to be almost stopped. The > essential design of overlayfs is based upon UnionMount, and I have > pointed out several issues such as > - for users, the inode number may change silently. eg. copy-up. > - hardlinks may break by copy-up. > - read(2) may get an obsoleted filedata (fstat(2) for metadata too). > - fcntl(F_SETLK) may be broken by copy-up. > - unnecessary copy-up may happen, for example mmap(MAP_PRIVATE) after > open(O_RDWR). > - Later I noticed one more thing. /proc/PID/{fd/,exe} may not work > correctly for overlayfs ... > - etc... > They are called "unPOSIXy behavior", and unforunately many of them are > NOT seem to be addressed in recent patches either. > > Also I have posted > If the development of UnionMount is really stopped, then I'd ask people > to consider merging aufs as well as overlayfs. > but I am not sure whether LKML people are still waiting for UnionMount > and rejecting aufs. > Okajima san /o\, thanks for the short summary of history, quick overview of AUFS features and OverlayFS design. I can't say much about AUFS, I just simply used it for so long. But it looks like you agree with me that something should happen in case of Union Filesystem's. Anyway, as said I would like to see an upstream solution in the near future. If this will be AUFS, I am OK with that decision. Regards, - Sedat - > J. R. Okajima -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/