From: Jan Olszak <j.olszak@samsung.com>
To: David Howells <dhowells@redhat.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
"linux-unionfs@vger.kernel.org" <linux-unionfs@vger.kernel.org>
Subject: Re: Optional switching off cow in overlayfs
Date: Tue, 23 Jun 2015 18:05:39 +0200 [thread overview]
Message-ID: <558983D3.3040205@samsung.com> (raw)
In-Reply-To: <32715.1435065828@warthog.procyon.org.uk>
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On 06/23/2015 03:23 PM, David Howells wrote:
> Jan Olszak <j.olszak@samsung.com> wrote:
>
>> Why not just say: "rename causes copy" and leave everything as it is now.
> That's another option - but your whole proposal was that we specifically don't
> copy up these files IIRC.
Yes, so let's modify the proposal:
Overlayfs checks xattr "trusted.overlay.cow" to switch COW off whenever
it's possible.
1. This would be an optimization/convenience option, not a sercurity
option.
2. By default overlayfs uses COW like it does now
3. trusted.overlay.cow=="n" means:
1. Unlink, open, setattr etc. use the original inode from lowerdir
2. Unmodifying operations also use inode from lowerdir
3. Other operations (rename) may copy the file if it's required by
the implementation of overlayfs
Thanks,
Jan
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next prev parent reply other threads:[~2015-06-23 16:05 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-18 13:25 Optional switching off cow in overlayfs Jan Olszak
2015-06-18 13:39 ` David Howells
2015-06-18 14:43 ` Jan Olszak
2015-06-22 11:32 ` Miklos Szeredi
2015-06-22 13:45 ` Jan Olszak
2015-06-22 13:53 ` Miklos Szeredi
2015-06-22 14:26 ` Jan Olszak
2015-06-22 14:37 ` Miklos Szeredi
2015-06-22 15:32 ` Jan Olszak
2015-06-23 9:27 ` David Howells
2015-06-23 10:36 ` Jan Olszak
2015-06-23 13:23 ` David Howells
2015-06-23 16:05 ` Jan Olszak [this message]
2015-06-23 16:07 ` Jan Olszak
2015-06-24 16:03 ` Jan Olszak
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