Re: [PATCH 4/5] NFS: remove RPC PipeFS mount point reference from blocklayout routines

On Tue, 2011-11-29 at 23:30 +0800, Peng Tao wrote: 

On Tue, Nov 29, 2011 at 11:18 PM, Trond Myklebust
[off-list ref] wrote:

quoted

On Tue, 2011-11-29 at 23:10 +0800, Peng Tao wrote:

quoted

On Tue, Nov 29, 2011 at 9:35 PM, Myklebust, Trond
[off-list ref] wrote:

quoted

quoted

-----Original Message-----
From: tao.peng@emc.com [mailto:tao.peng@emc.com]
Sent: Tuesday, November 29, 2011 7:40 AM
To: skinsbursky@parallels.com
Cc: Myklebust, Trond; linux-nfs@vger.kernel.org; xemul@parallels.com;
neilb@suse.de; netdev@vger.kernel.org; linux-kernel@vger.kernel.org;
jbottomley@parallels.com; bfields@fieldses.org; davem@davemloft.net;
devel@openvz.org
Subject: RE: [PATCH 4/5] NFS: remove RPC PipeFS mount point reference
from blocklayout routines

quoted

-----Original Message-----
From: Stanislav Kinsbursky [mailto:skinsbursky@parallels.com]
Sent: Tuesday, November 29, 2011 8:19 PM
To: Peng, Tao
Cc: Trond.Myklebust@netapp.com; linux-nfs@vger.kernel.org; Pavel
Emelianov; neilb@suse.de; netdev@vger.kernel.org;
linux-kernel@vger.kernel.org; James Bottomley; bfields@fieldses.org;
davem@davemloft.net; devel@openvz.org
Subject: Re: [PATCH 4/5] NFS: remove RPC PipeFS mount point reference
from blocklayout routines

29.11.2011 16:00, tao.peng@emc.com пишет:

quoted

quoted

-----Original Message-----
From: linux-nfs-owner@vger.kernel.org
[mailto:linux-nfs-owner@vger.kernel.org] On Behalf Of

Stanislav

quoted

quoted

Kinsbursky
Sent: Tuesday, November 29, 2011 6:11 PM
To: Trond.Myklebust@netapp.com
Cc: linux-nfs@vger.kernel.org; xemul@parallels.com; neilb@suse.de;
netdev@vger.kernel.org; linux- kernel@vger.kernel.org;
jbottomley@parallels.com; bfields@fieldses.org;
davem@davemloft.net; devel@openvz.org
Subject: [PATCH 4/5] NFS: remove RPC PipeFS mount point reference
from blocklayout routines

This is a cleanup patch. We don't need this reference anymore,
because blocklayout pipes dentries now creates and destroys in
per-net operations and on PipeFS mount/umount notification.
Note that nfs4blocklayout_register_net() now returns 0 instead of
-ENOENT in case of PipeFS superblock absence. This is ok, because
blocklayout pipe dentry will be created on PipeFS mount event.

When is the "pipefs mount event" going to happen? When inserting
kernel modules or when user issues

mount command?

quoted

When user issues mount command.
Kernel mounts of PipeFS has been removed with all these patch sets
I've sent already.

Then it is going to break blocklayout user space program blkmapd, which is
stared before mounting any file system and it tries to open the pipe file
when started.

Why on earth is blkmapd doing this instead of listening for file creation notifications like the other rpc_pipefs daemons do?

Not sure how the original implementer chose this but I think it is
likely because we do not expect the pipe file to be created or deleted
dynamically.

Unless blkmapd can pin the sunrpc module (which it shouldn't be able to)
then that assumption would be wrong. Please look into fixing blkmapd...

Sorry, I don't quite get it. Do you mean sunrpc module may be removed
while nfs/blocklayout modules are still in use? Please explain it a
bit. Thanks.

I mean that I'm perfectly entitled to do

'modprobe -r blocklayoutdriver'

and when I do that, then I expect blkmapd to close the rpc pipe and wait
for a new one to be created just like rpc.idmapd and rpc.gssd do when I
remove the nfs and sunrpc modules.

-- 
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust@netapp.com
www.netapp.com