Re: [RFC PATCH 0/4] namespacefs: Proof-of-Concept

From: ebiederm@xmission.com (Eric W. Biederman)
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Yordan Karadzhov \(VMware\)" <y.karadz@gmail.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	viro@zeniv.linux.org.uk, mingo@redhat.com, hagen@jauu.net,
	rppt@kernel.org, James.Bottomley@HansenPartnership.com,
	akpm@linux-foundation.org, vvs@virtuozzo.com,
	shakeelb@google.com, christian.brauner@ubuntu.com,
	mkoutny@suse.com, Linux Containers <containers@lists.linux.dev>
Subject: Re: [RFC PATCH 0/4] namespacefs: Proof-of-Concept
Date: Thu, 18 Nov 2021 13:22:16 -0600	[thread overview]
Message-ID: <87pmqxuv4n.fsf@email.froward.int.ebiederm.org> (raw)
In-Reply-To: <20211118140211.7d7673fb@gandalf.local.home> (Steven Rostedt's message of "Thu, 18 Nov 2021 14:02:11 -0500")

Steven Rostedt <rostedt@goodmis.org> writes:

> On Thu, 18 Nov 2021 12:55:07 -0600
> ebiederm@xmission.com (Eric W. Biederman) wrote:
>
>> Nacked-by: "Eric W. Biederman" <ebiederm@xmission.com>
>> 
>> Eric
>
> Eric, 
>
> As you can see, the subject says "Proof-of-Concept" and every patch in the
> the series says "RFC". All you did was point out problems with no help in
> fixing those problems, and then gave a nasty Nacked-by before it even got
> into a conversation.
>
> From this response, I have to say:
>
>   It is not correct to nack a proof of concept that is asking for
>   discussion.
>
> So, I nack your nack, because it's way to early to nack this.

I am refreshing my nack on the concept.  My nack has been in place for
good technical reasons since about 2006.

I see no way forward.  I do not see a compelling use case.

There have been many conversations in the past attempt to implement
something that requires a namespace of namespaces and they have never
gotten anywhere.

I see no attempt a due diligence or of actually understanding what
hierarchy already exists in namespaces.

I don't mean to be nasty but I do mean to be clear.  Without a
compelling new idea in this space I see no hope of an implementation.

What they are attempting to do makes it impossible to migrate a set of
process that uses this feature from one machine to another.  AKA this
would be a breaking change and a regression if merged.

The breaking and regression are caused by assigning names to namespaces
without putting those names into a namespace of their own.   That
appears fundamental to the concept not to the implementation.

Since the concept if merged would cause a regression it qualifies for
a nack.

We can explore what problems they are trying to solve with this and
explore other ways to solve those problems.  All I saw was a comment
about monitoring tools and wanting a global view.  I did not see
any comments about dealing with all of the reasons why a global view
tends to be a bad idea.

I should have added that we have to some extent a way to walk through
namespaces using ioctls on nsfs inodes.

Eric