linux-kernel - Re: Copy on write hard links?

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Message-ID: <CAFLxGvzCp1JDL5yfuk7oRBGqi+re=NZWr-mg6nahs9NjFyDYwA@mail.gmail.com>
Date:	Sun, 29 Sep 2013 09:14:25 +0200
From:	Richard Weinberger <richard.weinberger@...il.com>
To:	Pádraig Brady <P@...igbrady.com>
Cc:	Thomas Meyer <thomas@...3r.de>, Rob Landley <rob@...dley.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Copy on write hard links?

On Sun, Sep 29, 2013 at 7:22 AM, Pádraig Brady <P@...igbrady.com> wrote:
> On 09/25/2013 03:37 PM, richard -rw- weinberger wrote:
>> On Wed, Sep 25, 2013 at 4:28 PM, Thomas Meyer <thomas@...3r.de> wrote:
>>> Am Mittwoch, den 25.09.2013, 08:59 -0500 schrieb Rob Landley:
>>>> On 09/24/2013 01:36:56 PM, Thomas Meyer wrote:
>>>>> Hi,
>>>>>
>>>>> Is there such a thing?
>>>>
>>>> In the kernel's vfs layer?
>>>
>>> Yes, that would be a nice feature!
>>
>> You mean reflinks?
>> Currently only OCFS2 and btrfs support them.
>> Both using a fs specific ioctl().
>> IIRC GNU cp uses the btrfs specific one if the --reflink parameter is used.
>
> coreutils is waiting for a reflink syscall to materialize
> rather than adding new per filesystem support
> http://lwn.net/Articles/335380/

Is this the correct link? It's a proposal for a reflink() syscall.
But corrently both OCFS2 and btrfs are using ioctl().

Digging into GNU coreutils shows that their cp's
clone_file() only supports the btrfs ioctl().
I don't know what the GNU folks big plan is, maybe you know more. :-)

-- 
Thanks,
//richard
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