On Thu, 2012-03-15 at 23:23 -0700, Boaz Harrosh wrote:
> From: Sachin Bhamare <sbhamare@xxxxxxxxxxx>
>
> The pnfs-objects protocol mandates that we autologin into devices not
> present in the system, according to information specified in the
> get_device_info returned from the server.
>
> The Protocol specifies two login hints.
> 1. An IP address:port combination
> 2. A string URI which is constructed as a URL with a protocol prefix
> followed by :// and a string as address. For each protocol prefix
> the string-address format might be different.
>
> We only support the second option. The first option is just redundant
> to the second one.
> NOTE: The Kernel part of autologin does not parse the URI string. It
> just channels it to a user-mode script. So any new login protocols should
> only update the user-mode script which is a part of the nfs-utils package,
> but the Kernel need not change.
>
> We implement the autologin by using the call_usermodehelper() API.
> (Thanks to Steve Dickson <steved@xxxxxxxxxx> for pointing it out)
> So there is no running daemon needed, and or special setup.
>
> All is needed is that "/sbin/osd_login" script exists.
> TODO:
> "osd_login" is an hard coded name. If not present we will rate_limit
> print to dmsg and keep failing. In such cases we should stop trying
> and provide sysfs interface for re-enabling autologin. For example,
> we could ZERO out the script name and let user-mode set a new script
> name.
> [Q] Where in sysfs should a layout-driver put its things?
Please see fs/nfs/cache_lib.c, which already does this sort of thing.
The right thing to do is not sysfs, but a kernel module parameter.
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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