linux-kernel - Re: [RFC PATCH 0/7] cross rename

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Date:	Wed, 02 Oct 2013 22:36:29 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Miklos Szeredi <miklos@...redi.hu>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Christoph Hellwig <hch@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Howells <dhowells@...hat.com>,
	"zab@...hat.com" <zab@...hat.com>, Jan Kara <jack@...e.cz>,
	"Theodore Ts'o" <tytso@....edu>, Miklos Szeredi <mszeredi@...e.cz>
Subject: Re: [RFC PATCH 0/7] cross rename

Yes... Al  and I had a brief conversation about the complexities over IRC this evening.

Linus Torvalds <torvalds@...ux-foundation.org> wrote:
>On Wed, Oct 2, 2013 at 6:58 PM, H. Peter Anvin <hpa@...or.com> wrote:
>>
>> I would suggest it shouldn't be renameat2() but rather renameat3(),
>i.e.
>> rename file A -> B, if B exists rename B to C.  It may not be
>desirable
>> to expose the stale B in the same namespace as A, but still want it
>to
>> be possible to scavenge it.  Obviously, A=C is a valid subcase.
>
>I really *really* prefer to stay with two names. Miklos had an earlier
>three-name version, and it was hugely more complex, and it does not
>fit nearly as well in the model.
>
>Two directory entries is also what the current rename() effectively
>always does (clearing one, changing another). So doing the
>cross-rename model is actually fairly close to a normal rename. A
>three-way one is not actually at all similar.
>
>So I was actually very relieved to see this much simpler and cleaner
>model, because the alternative really was nasty. This one looks fairly
>simple and clean and straightforward. The previous was none of that.
>
>              Linus

-- 
Sent from my mobile phone.  Please pardon brevity and lack of formatting.
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