linux-kernel - Re: [NFS] NFS on loopback locks up entire system(2.6.23-rc6)?

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Message-ID: <92cbf19b0709210920p3647788dl11d8c4e0cee1f70f@mail.gmail.com>
Date:	Fri, 21 Sep 2007 09:20:06 -0700
From:	"Chakri n" <chakriin5@...il.com>
To:	"Trond Myklebust" <Trond.Myklebust@...app.com>
Cc:	nfs@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [NFS] NFS on loopback locks up entire system(2.6.23-rc6)?

Thanks.

I was using flock (BSD locking) and I think the problem should be
solved if I move my application to use POSIX locks.

And any option to avoid processes waiting indefinitely to free pages
from NFS requests waiting on unresponsive NFS server?

Thanks
--Chakri

On 9/21/07, Trond Myklebust <Trond.Myklebust@...app.com> wrote:
> On Thu, 2007-09-20 at 20:12 -0700, Chakri n wrote:
> > Thanks Trond, for clarifying this for me.
> >
> > I have seen similar behavior when a remote NFS server is not
> > available. Many processes wait end up waiting in nfs_release_page. So,
> > what will happen if the remote server is not available,
> > nfs_release_page cannot free the memory since it waits on rpc request
> > to complete, which never completes and processes wait in there for
> > ever?
> >
> > And unfortunately in my case, I cannot use "mount --bind". I want to
> > use the same file system from two different nodes, and I want file &
> > record locking to be consistent. The only way to make sure locking is
> > consistent is to use loopback NFS on 1 host and NFS mount the same
> > file system on other nodes, so that NFS server ensures file & record
> > locking to be consistent. Is there any alternative to this?
> >
> > Is it possible or any efforts to integrate ext3 or other local file
> > systems locking & network file system locking, so that user can use
> > "mount --bind" on local host and NFS mount on remote nodes, but file &
> > record locking will be consistent between both the nodes?
>
> Could you be a bit more specific? Is the problem that your application
> is using BSD locks (flock()) instead of POSIX locks?
>
> Cheers
>    Trond
>
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