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Date: Fri, 04 Mar 2011 11:21:54 -0500
From: Steve Dickson <SteveD@redhat.com>
To: Masatake YAMATO <yamato@redhat.com>
CC: linux-nfs@vger.kernel.org
Subject: Re: [PATCH 1/2] Read /etc/exports.d/*.export as extra export files
References: <20110217.215900.388120588347145930.yamato@redhat.com>	<20110303.230122.1012453714437438591.yamato@redhat.com>	<4D6FFF80.6030102@RedHat.com> <20110304.151026.946624858093159104.yamato@redhat.com>
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On 03/04/2011 01:10 AM, Masatake YAMATO wrote:
> Hi,
> 
> thank you for replying.
Again.. my apologies for taking so long... 

> 
>> On 03/03/2011 09:01 AM, Masatake YAMATO wrote:
>>> No comment?
>> Sorry about that... I was traveling for the couple weeks... 
>>
>> Would you happen to have an example script on how 
>> this new feature would be used? I just want to run 
>> some quick tests...
>>
>> tia,
>>
>> steved.
> 
> Could you try following one?
> 
> # cd /tmp
> # mkdir /tmp/alpha
> # mkdir /tmp/beta
> # mkdir /etc/exports.d
> # mkdir /etc/exports.d
> # echo '/tmp/alpha *(ro)' > /etc/exports.d/alpha.export
> # echo '/tmp/beta *(ro)'  > /etc/exports.d/beta.export
> # /etc/init.d nfs restart
> 
> After above setting up, when you do `exportfs', following lines 
> may be included in the output:
> 
>     /tmp/alpha	 <world>
>     /tmp/beta        <world>
Question... Where is the race? Meaning who is reading the exports
file while its being modified?

The reason I ask is exporting (or re-exporting) pretty serial:

exportfs read /etc/exports
exportfs writes the new exports to /var/lib/nfs/etab
mountd notices etab has changed and rereads its.
mountd flush the kernel cache cause the kernel to do upcalls to get the new exports.

So since exportfs command not a daemon I don't see why 
   cp exports.new /etc/exports && exportfs -arv

isn't all that is needed.  What am I missing?

steved.