[BBLISA] Does read only really mean it?

[Bill Bogstad]

On Thu, Dec 5, 2013 at 10:03 AM, Edward Ned Harvey (bblisa4)
<bblisa4 at nedharvey.com> wrote:
>> From: bblisa-bounces at bblisa.org [mailto:bblisa-bounces at bblisa.org] On
>> Behalf Of Alex Aminoff
>>
>> Nevertheless, I tested it and unless I messed up my test, an NFS mount
>> with -o ro, you read a file on the mounted FS, and the access time is
>> updated.
>
> Oh - that could explain it right there -
>
> I think the client isn't the one doing the update.  I think your server is updating the last access time on the file, because the server served the file to the client.  The server doesn't necessarily know you mounted read-only.

That makes a lot of sense.   Alex doesn't say what version of the NFS
protocol he is using, but a quick check of the RFC for the MOUNT
protocol for NFSv3 (see page 105 for mount protocol
http://www.ietf.org/rfc/rfc1813.txt) doesn't seem to give a way for a
client to indicate that it wants to mount a filesystem as readonly.
Maybe someone who is more familiar with the NFS protocol can confirm
this.

More generally, my recollection of the various NFS protocols is that
they have always concentrated on ease of implementation/performance
rather then either de jure (POSIX) or de facto (general Unix/Linux
implementation) "standards".

Bill Bogstad