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@redhat.com> for pointing it out)
So there is no running daemon needed, and/or special setup.
We Add the osd_login_prog Kernel module parameters which defaults to:
/sbin/osd_login
Kernel try's to upcall the program specified in osd_login_prog. If the file is
not found or the execution fails Kernel will disable any farther upcalls, by
zeroing out osd_login_prog, Until Admin re-enables it by setting the
osd_login_prog parameter to a proper program.
Also add text about the osd_login program command line API to:
Documentation/filesystems/nfs/pnfs.txt
and documentation of the new osd_login_prog module parameter to:
Documentation/kernel-parameters.txt
TODO: Add timeout option in the case osd_login program gets
stuck
Signed-off-by: Sachin Bhamare <sbhamare@panasas.com>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
18d98f6c04