linux-kernel - Re: [RFC PATCH] nbd: set the default nbds

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Message-ID: <63658620-7d1f-f626-b637-8f551ca07f95@redhat.com>
Date:   Thu, 30 May 2019 09:22:32 +0800
From:   Xiubo Li <xiubli@...hat.com>
To:     Josef Bacik <josef@...icpanda.com>
Cc:     axboe@...nel.dk, nbd@...er.debian.org, mchristi@...hat.com,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        atumball@...hat.com
Subject: Re: [RFC PATCH] nbd: set the default nbds_max to 0

On 2019/5/29 21:48, Josef Bacik wrote:
> On Wed, May 29, 2019 at 04:08:36PM +0800, xiubli@...hat.com wrote:
>> From: Xiubo Li <xiubli@...hat.com>
>>
>> There is one problem that when trying to check the nbd device
>> NBD_CMD_STATUS and at the same time insert the nbd.ko module,
>> we can randomly get some of the 16 /dev/nbd{0~15} are connected,
>> but they are not. This is because that the udev service in user
>> space will try to open /dev/nbd{0~15} devices to do some sanity
>> check when they are added in "__init nbd_init()" and then close
>> it asynchronousely.
>>
>> Signed-off-by: Xiubo Li <xiubli@...hat.com>
>> ---
>>
>> Not sure whether this patch make sense here, coz this issue can be
>> avoided by setting the "nbds_max=0" when inserting the nbd.ko modules.
>>
> Yeah I'd rather not make this the default, as of right now most people still
> probably use the old method of configuration and it may surprise them to
> suddenly have to do nbds_max=16 to make their stuff work.  Thanks,

Sure, make sense to me :-)

So this patch here in the mail list will as one note and reminder to 
other who may hit the same issue in future.

Thanks.
BRs
Xiubo


> Josef
>