From: Ian Kent <raven@themaw.net>
To: Jeff Mahoney <jeffm@suse.com>, autofs@vger.kernel.org
Subject: Re: mount -oaddr=<ipaddr> ?
Date: Fri, 08 Apr 2016 08:21:45 +0800 [thread overview]
Message-ID: <1460074905.3135.19.camel@themaw.net> (raw)
In-Reply-To: <5703BB28.9000508@suse.com>
On Tue, 2016-04-05 at 09:18 -0400, Jeff Mahoney wrote:
> On 4/4/16 11:12 PM, Ian Kent wrote:
> > On Mon, 2016-04-04 at 20:55 -0400, Jeff Mahoney wrote:
> > > Hi all -
> > >
> > > I'm investigating an issue where our user updated from SLE11 to
> > > SLE12
> > > and the hostname for autofs mounts stopped appearing in the
> > > 'mount'
> > > output. I know why this happens, what the reason for it being
> > > this
> > > way
> > > is, and that it can be overridden by setting the
> > > use_hostname_for_mounts=yes option (and the side effects). Before
> > > I
> > > go
> > > and write up the patch implementing it, is there a reason why
> > > autofs
> > > doesn't pass the hostname in the mount source and specify the ip
> > > address
> > > using the -oaddr=<ipaddr> option? Was this tried and found to be
> > > wanting somehow?
> >
> > TBH I didn't even consider doing that.
> >
> > But the daemon needs to be conservative in the options it uses
> > because
> > maps may be used with other platforms and unknown or non-standard
> > options can cause mount failures.
> >
> > While Linux mount.nfs(8) has the sloppy option (which maintainers
> > seem
> > to try and remove from time to time) other platforms probably don't.
> >
> > The addr=<address> option isn't listed as a valid option in nfs(5)
> > and
> > neither is it listed in on-line Solaris documentation that I could
> > find
> > so I'm not sure making the daemon use it is a good idea.
> >
> > Maybe there's another way...
> >
> > Note that I do need to be able to mount to a specific IP address
> > while
> > specifying the host name in the mount command but don't know of a
> > way todo it.
>
> After looking at it again, the kernel supports doing this but nfs
> -utils
> explicitly doesn't.
>
> A closer look at nfs-utils also shows that, given a hostname,
> mount.nfs
> will iterate over all available addresses matching the specification
> (e.g. constrained by proto=) and try to mount using each one. It will
> properly pass an addr= field to the kernel but it ignores the one
> passed
> on the mount command line. It will use getaddrinfo() to get the list
> of
> addresses for the remote host and then iterate over them, retrying
> until
> it finds one that works. So that part of it works, but the
> prioritization implemented by the replicated modules isn't. I wonder
> if
> it would make sense to move that to nfs-utils instead. It seems like
> it
> would be generally useful.
I'm not sure that's a good idea.
The syntax that would need to be supported by nfs-utils for this is used
by OSes that provide read-only replicated mount fail over.
So, as soon as that was added people will assume the Linux kernel NFS
client has this fail over support which it hasn't.
Ian
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prev parent reply other threads:[~2016-04-08 0:21 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-05 0:55 mount -oaddr=<ipaddr> ? Jeff Mahoney
2016-04-05 3:12 ` Ian Kent
2016-04-05 13:18 ` Jeff Mahoney
2016-04-08 0:21 ` Ian Kent [this message]
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