From: Miklos Szeredi <miklos@szeredi.hu>
To: Jan Olszak <j.olszak@samsung.com>
Cc: David Howells <dhowells@redhat.com>,
"linux-unionfs@vger.kernel.org" <linux-unionfs@vger.kernel.org>
Subject: Re: Optional switching off cow in overlayfs
Date: Mon, 22 Jun 2015 13:32:09 +0200 [thread overview]
Message-ID: <CAJfpegsP-_MAKybYZ=uS3UCxsxL9Hv-cJ-GYrVL4h3B+tWZF9A@mail.gmail.com> (raw)
In-Reply-To: <5582D8F7.1060700@samsung.com>
On Thu, Jun 18, 2015 at 4:43 PM, Jan Olszak <j.olszak@samsung.com> wrote:
>
>
> On 06/18/2015 03:39 PM, David Howells wrote:
>>
>> Jan Olszak <j.olszak@samsung.com> wrote:
>>
>>> I was wondering about a small improvement to overlayfs - optional, per
>>> file
>>> copy of write.
>>>
>>> 1. By default overlayfs would work as usual.
>>> 2. If a file in 'lower' filesystem has an xattr set
>>> (e.g. trusted.overlay.cow=n) the file would not be copied.
>>>
>>> What do you think?
>>
>> Ummm. What's the use case? How do you handle the file being part of
>> multiple
>> overlays?
>>
>> David
>>
>
> I wan't to achieve 'files' granularity in overlayfs instead of 'directory'
> granularity.
> It would be useful in Linux containers configuration. Sometimes you don't
> have the
> power to change the images that are run inside containers and in one folder
> you have both:
> - files that have to be copied
> - files that don't really need to be copied
>
>
> trusted.overlay.cow==n indicates switching off copying the file to the upper
> layer.
> So with multiple overlays you would always have only one file from the
> lower-most dir.
What type filesystem is the lowest layer? Can you set immutable on
it (chattr +i)? That would be the logical way to say "nobody can
modify this file, not even root".
Thanks,
Miklos
next prev parent reply other threads:[~2015-06-22 11:32 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 [this message]
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
2015-06-23 16:07 ` Jan Olszak
2015-06-24 16:03 ` Jan Olszak
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