Re: [PATCH] rpc.nfsd: mount up nfsdfs is it doesn't appear to be mounted yet

[Steve Dickson <SteveD@redhat.com>]

On 08/30/2010 12:16 PM, Jeff Layton wrote:
> On Mon, 30 Aug 2010 11:51:48 -0400
> Steve Dickson <SteveD@redhat.com> wrote:
> 
>>
>>
>> On 08/28/2010 07:35 AM, Jeff Layton wrote:
>>> There's a bit of a chicken and egg problem when nfsd is run the first
>>> time. On Fedora/RHEL at least, /proc/fs/nfsd is mounted up whenever nfsd
>>> is plugged in via a modprobe.conf "install" directive.
>>>
>>> If someone runs rpc.nfsd without plugging in nfsd.ko first,
>>> /proc/fs/nfsd won't be mounted and rpc.nfsd will end up using the legacy
>>> nfsctl interface. After that, nfsd will be plugged in and subsequent
>>> rpc.nfsd invocations will use that instead.
>>>
>>> This is a problem as some nfsd command-line options are ignored when the
>>> legacy interface is used. It'll also be a problem for people who want
>>> IPv6 enabled servers. The upshot is that we really don't want to use the
>>> legacy interface unless there is no other option.
>> Well maybe its time we stop supporting the legacy interface... I
>> would rather stop supporting something nobody uses then added
>> some questionable code... Lets just error out when /proc/fs/nfsd
>> is not mounted and log what needs to happen...
>>
>> steved.
>>
> 
> Hmmm...if I had known that it was ok to stop supporting old kernels,
> the IPv6 support for rpc.nfsd would have been a heck of a lot easier to
> implement.
I thought you said the legacy interface would not work with IPV6 or
did I misunderstand you? 

> 
> I'm not sure I like throwing up our hands and bailing out with a log
> message. We'll be going from an at least somewhat carefully considered
> fallback mechanism to an outright failure to start in this situation.
> That doesn't really seem like an improvement to me...
This case will only happen when people start rpc.nfsd by hand (i.e. not
via some start-up script) which %99.999 of the users do not do
.
But the few that do start rpc.nfsd by hand, they are probably debugging
something, so logging a message saying /proc/fs/nfsd is not mount 
would be quite handy... IMHO... 


> 
> How this as an alternate proposal?
> 
> We attempt to mount up nfsdfs. If the "threads" file still isn't
> present after the attempt, we then log a warning and go with the
> nfsctl() interface?
Has anybody test this legacy interface lately?? Does anybody anybody
depend on the existence of this interface??? I would guess the answer
would be no to both questions... So I see this as an opportunity so
simplify the code... which is always a good thing... 

So I would have no problem saying from the next release of nfs-utils,
the legacy interface is no longer supported... especially if there are
issues with IPV6.

steved.