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From: Miklos Szeredi <miklos@szeredi.hu>
To: Michal Suchanek <hramrach@centrum.cz>
Cc: Jiri Kosina <jkosina@suse.cz>, Ric Wheeler <ricwheeler@gmail.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	David Howells <dhowells@redhat.com>, Ian Kent <ikent@redhat.com>,
	Jeff Moyer <jmoyer@redhat.com>,
	Christoph Hellwig <hch@infradead.org>
Subject: Re: Unionmount status?
Date: Fri, 15 Apr 2011 14:48:05 +0200	[thread overview]
Message-ID: <BANLkTinmWtL0U2L7+DFeHW0R9Kpy-JevcA@mail.gmail.com> (raw)
In-Reply-To: <BANLkTikHKGLQvShJBL0P7XJ9XQ3EpgYxuQ@mail.gmail.com>

On Fri, Apr 15, 2011 at 2:34 PM, Michal Suchanek <hramrach@centrum.cz> wrote:
> On 15 April 2011 14:29, Miklos Szeredi <miklos@szeredi.hu> wrote:
>> 2) take whiteout/opaque support from union mounts and use that
>
> How far from importing full unionmount is that?

Whiteout/opaque support is quite separate from the rest of union
mounts, and could be reusable for overlayfs.

There are several reasons why I didn't want to go that way with:

- lots of filesystems would have to be updated
- it introduces incompatibility in the filesystem format, which can be
a real pain (not for tmpfs, obviously, since tmpfs doesn't have a
persistent backing)

There *are* advantages to doing whiteouts in the filesystem, for
example it makes file removal atomic.  But atomicity is something that
needs to be addressed in lots of other places (e.g. copy up) not just
during whiteout, and there are other ways to do that than push the
responsibility into each and every filesystem.

Thanks,
Miklos

  reply	other threads:[~2011-04-15 12:48 UTC|newest]

Thread overview: 94+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-12 15:00 Unionmount status? Michal Suchanek
2011-04-12 20:31 ` Ric Wheeler
2011-04-12 21:36   ` Michal Suchanek
2011-04-13 14:18     ` Jiri Kosina
2011-04-13 15:13       ` Michal Suchanek
2011-04-14  8:38         ` Miklos Szeredi
2011-04-14  9:48           ` Sedat Dilek
2011-04-14  9:58             ` Miklos Szeredi
2011-04-15 11:22           ` Michal Suchanek
2011-04-15 11:31             ` Miklos Szeredi
2011-04-15 11:51               ` Michal Suchanek
2011-04-15 12:29                 ` Miklos Szeredi
2011-04-15 12:34                   ` Michal Suchanek
2011-04-15 12:48                     ` Miklos Szeredi [this message]
2011-04-15 21:48                   ` Hugh Dickins
2011-04-15 22:18                   ` Andreas Dilger
2011-04-18 13:31                     ` Michal Suchanek
2011-04-19 20:04                       ` [PATCH] tmpfs: implement generic xattr support Miklos Szeredi
2011-04-20  2:18                         ` Phillip Lougher
2011-04-20 13:43                           ` Miklos Szeredi
2011-04-21  6:59                             ` Michal Suchanek
2011-04-21  9:08                               ` Miklos Szeredi
2011-04-21 10:59                                 ` Michal Suchanek
2011-04-21 14:58                                   ` Jordi Pujol
2011-04-21 15:22                                     ` Michal Suchanek
2011-04-21 15:43                                       ` Michal Suchanek
2011-04-21 17:26                                         ` Miklos Szeredi
2011-04-21 19:17                                           ` Michal Suchanek
2011-04-20 16:00                         ` Serge E. Hallyn
2011-05-12  4:20                         ` Hugh Dickins
2011-05-12  7:52                           ` Michal Suchanek
2011-05-12 12:27                           ` Miklos Szeredi
2011-05-12 14:00                             ` Miklos Szeredi
2011-05-12 16:52                               ` Hugh Dickins
2011-04-18 13:34                     ` Unionmount status? Michal Suchanek
2011-04-18 13:37                     ` Michal Suchanek
2011-04-13 17:26     ` Ric Wheeler
2011-04-13 18:58       ` Michal Suchanek
2011-04-13 19:11         ` Ric Wheeler
2011-04-13 19:47           ` Michal Suchanek
2011-04-14  4:50             ` Ian Kent
2011-04-14  9:32               ` Michal Suchanek
2011-04-14  9:40                 ` Miklos Szeredi
2011-04-14 13:21                   ` Ric Wheeler
2011-04-14 14:54                     ` Michal Suchanek
2011-04-15 16:31                       ` Ric Wheeler
2011-04-14 19:14             ` David Howells
2011-06-29  9:39               ` Union mount and overlayfs bake off? Ric Wheeler
2011-06-29 11:40                 ` Michal Suchanek
2011-06-29 10:17               ` David Howells
2011-06-30 12:44                 ` Miklos Szeredi
2011-07-10  8:28                 ` Union mount and lockdep design issues Ric Wheeler
2011-07-10 13:48                   ` Peter Zijlstra
2011-07-11  8:35                     ` Michal Suchanek
2011-07-11 11:01                   ` David Howells
2011-07-11 12:00                     ` Peter Zijlstra
2011-07-11 13:36                       ` Michal Suchanek
2011-07-11 13:50                         ` Ian Kent
2011-07-11 16:17                           ` Michal Suchanek
2011-07-11 17:23                             ` Ian Kent
2011-07-11 18:08                               ` Michal Suchanek
2011-07-12  8:30                                 ` Miklos Szeredi
2011-07-12  9:58                                   ` Michal Suchanek
2011-07-12 11:45                                     ` Miklos Szeredi
2011-07-12 18:49                                       ` Michal Suchanek
2011-07-13  9:49                                         ` Miklos Szeredi
2011-07-13 12:02                                 ` David Howells
2011-07-13 13:20                                   ` Miklos Szeredi
2011-07-14  0:57                                   ` David Howells
2011-07-11 13:54                     ` David Howells
2011-07-11 14:02                       ` Peter Zijlstra
2011-07-11 14:50                         ` [PATCH 1/2] VFS: Pass mount flags to sget() David Howells
2011-07-11 14:50                         ` [PATCH 2/2] union-mount: Duplicate the i_{, dir_}mutex lock classes and use for upper layer David Howells
  -- strict thread matches above, loose matches on Subject: below --
2010-03-19  0:21 UnionMount status? Michal Suchanek
2010-03-19  6:10 ` J. R. Okajima
2010-03-19 20:28   ` Michal Suchanek
2010-03-19 20:59     ` J. R. Okajima
2010-03-19 18:03 ` Valerie Aurora
2010-03-19 21:47   ` Michal Suchanek
2010-03-20 16:41     ` Michal Suchanek
2010-03-23 23:02     ` Valerie Aurora
2010-04-01 15:36       ` Michal Suchanek
2010-07-14 13:12     ` Michal Suchanek
2010-07-14 19:30       ` Valerie Aurora
2010-07-19 16:06         ` Michal Suchanek
2010-08-10 16:52           ` Valerie Aurora
     [not found]             ` <AANLkTik+S2femtfOQvAYMayfN2N=PGvVL8J9=AD3_VCa@mail.gmail.com>
2010-08-16 18:52               ` Valerie Aurora
2010-08-17 12:03                 ` Michal Suchanek
2010-08-17 14:31                   ` Michal Suchanek
2010-08-17 19:51                     ` Valerie Aurora
2010-08-18 11:30                       ` Michal Suchanek
2010-08-18 19:06                         ` Valerie Aurora
2010-08-18 19:25                           ` Michal Suchanek
2010-07-12 13:01   ` Michal Suchanek

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