Message-ID: <496B4BBE.5040701@steeleye.com>
Date: Mon, 12 Jan 2009 08:55:10 -0500
From: Paul Clements <paul.clements@steeleye.com>
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To: Pavel Machek <pavel@suse.cz>
CC: kernel list <linux-kernel@vger.kernel.org>, Andrew Morton <akpm@osdl.org>
Subject: Re: do not allow two nbd-clients at same time
References: <20081208213542.GA10134@elf.ucw.cz> <20081208225758.GA2872@elf.ucw.cz> <20090112110322.GA2001@elf.ucw.cz>
In-Reply-To: <20090112110322.GA2001@elf.ucw.cz>
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Pavel Machek wrote:
> Two nbd-clients at same time are bad idea, and cause WARN_ON from nbd
> in 2.6.28-rc7 from sysfs_add_one. This simply prevents that from
> happening.

Thanks for this. But I think we also need the following:

--- drivers/block/nbd.c        2008-12-24 18:26:37.000000000 -0500
+++ drivers/block/nbd.c 2009-01-12 08:50:17.000000000 -0500
@@ -406,6 +406,7 @@ static int nbd_do_it(struct nbd_device *
         ret = sysfs_create_file(&disk_to_dev(lo->disk)->kobj, 
&pid_attr.attr);
         if (ret) {
                 printk(KERN_ERR "nbd: sysfs_create_file failed!");
+               lo->pid = 0;
                 return ret;
         }


To zero out pid in the error case. Otherwise, it looks good.

Thanks,
Paul

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