linux-kernel - Re: RFC: Revert move default dialect from CIFS to to SMB3

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Date:   Fri, 1 Sep 2017 20:56:50 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Steve French <smfrench@...il.com>
Cc:     "L. A. Walsh" <linux-cifs@...nx.org>,
        Thorsten Leemhuis <linux@...mhuis.info>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "linux-cifs@...r.kernel.org" <linux-cifs@...r.kernel.org>,
        Pavel Shilovsky <pshilov@...rosoft.com>
Subject: Re: RFC: Revert move default dialect from CIFS to to SMB3

On Fri, Sep 1, 2017 at 7:16 PM, Steve French <smfrench@...il.com> wrote:
>
> The default was SMB1 (CIFS) and was recently changed to SMB3.
> The dialect still can be overridden by specifying "vers=1.0" or "vers=2.1"
> etc. on mount.
>
> We just put together a patch to better explain the default changes
> (with additional warning messages) as suggested.
>
> SMB3 is significantly better than SMB2.1 (supporting encrypted shares
> and sessions for example, and requiring support for "secure negotiate")
> and some servers require SMB3 minimum as a result,

The default shouldn't be about "best and most secure", but "most
convenient, while still not actively *IN*secure"

So "some servers require 3.0" may be true, but if it's also the case
that "most servers still don't do 3.0 at all", then it's a "some" vs
"most".

Which is the most common one? That should be the default.

I realize that eventually we'll have auto-negotiation, but that's
clearly not for 4.13. So in the meantime the only issue is what the
right default should be without auto-negotiation.

So it should be about what the failure rate is. If trying for smb3 has
a high failure rate because people simply don't have that yet, then
making that the default was clearly the wrong choice.

Because being "better" is immaterial if it doesn't work.

              Linus