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

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Message-ID: <20190529134834.t6qjq2nkut37zpsf@MacBook-Pro-91.local>
Date:   Wed, 29 May 2019 09:48:36 -0400
From:   Josef Bacik <josef@...icpanda.com>
To:     xiubli@...hat.com
Cc:     josef@...icpanda.com, 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 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,

Josef