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Message-ID: <860e64ce-8f2e-4c07-a95c-18f72fb87216@pengutronix.de>
Date: Thu, 29 Feb 2024 11:38:16 +0100
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Subject: Re: [PATCH nfs-utils] start-statd: use flock -x instead of -e for
 busybox compatibility
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To: Calum Mackay <calum.mackay@oracle.com>, NeilBrown <neilb@suse.de>,
 Steve Dickson <steved@redhat.com>
Cc: linux-nfs@vger.kernel.org, kernel@pengutronix.de
References: <20240228185644.2743036-1-a.fatoum@pengutronix.de>
 <fd6db153-669f-4635-bacf-a23b0f7d2c7c@oracle.com>
From: Ahmad Fatoum <a.fatoum@pengutronix.de>
In-Reply-To: <fd6db153-669f-4635-bacf-a23b0f7d2c7c@oracle.com>
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Hello Calum,

On 28.02.24 22:09, Calum Mackay wrote:
> On 28/02/2024 6:56 pm, Ahmad Fatoum wrote:
>> busybox flock(1) only supports -x and not -e. util-linux flock(1)
>> treats both -e and -x the same, documents them both in its man page,
>> but lists only -x in its help output.
>>
>> Referring to util-linux git, it seems both options were added between
>> util-linux-2.13-pre1 and util-linux-2.13-pre2 back in 2006, so there
>> should be no harm in switching over to flock -x to avoid confusing
>> error output when attempting to mount a NFS on a busybox system:
>>
>>    $ mount -t nfs 192.168.2.13:/home/afa/nfsroot/imx8mn-evk /mnt
>>    flock: invalid option -- 'e'
>>    BusyBox v1.36.0 () multi-call binary.
>>
>>    Usage: flock [-sxun] FD | { FILE [-c] PROG ARGS }
>>
>>    [Un]lock file descriptor, or lock FILE, run PROG
>>
>>            -s      Shared lock
>>            -x      Exclusive lock (default)
>>            -u      Unlock FD
>>            -n      Fail rather than wait
>>
>> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> 
> hi Ahmad,
> 
> Since the default is an exclusive lock, in both BusyBox and util-linux, might it be simpler just to run flock without that option?

That would be another possibility, yes. I don't mind the explicitness in
specifying an argument, but I don't feel strongly either way.

Cheers,
Ahmad

> 
> best wishes,
> calum.
> 
>> ---
>>   utils/statd/start-statd | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/utils/statd/start-statd b/utils/statd/start-statd
>> index b11a7d91a7f6..67a2f4ad8e0e 100755
>> --- a/utils/statd/start-statd
>> +++ b/utils/statd/start-statd
>> @@ -8,7 +8,7 @@ PATH="/sbin:/usr/sbin:/bin:/usr/bin"
>>     # Use flock to serialize the running of this script
>>   exec 9> /run/rpc.statd.lock
>> -flock -e 9
>> +flock -x 9
>>     if [ -s /run/rpc.statd.pid ] &&
>>          [ "1$(cat /run/rpc.statd.pid)" -gt 1 ] &&
> 
> 

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