linux-kernel - Re: [PATCH] nbd:clear NBD_BOUND flag when NBD connection is closed

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Message-Id: <a1da3fff285fe13d04522f1a6e72bdc1@linux.vnet.ibm.com>
Date:   Thu, 13 Dec 2018 08:21:49 -0600
From:   Adriana Kobylak <anoo@...ux.ibm.com>
To:     medadyoung@...il.com, joel@....id.au, jk@...abs.org
Cc:     jbacik@...com, axboe@...nel.dk, linux-block@...r.kernel.org,
        openbmc@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        nbd@...er.debian.org,
        openbmc <openbmc-bounces+anoo=linux.ibm.com@...ts.ozlabs.org>
Subject: Re: [PATCH] nbd:clear NBD_BOUND flag when NBD connection is closed

On 2018-12-11 00:17, medadyoung@...il.com wrote:
> From: Medad <medadyoung@...il.com>
> 
>     If we do NOT clear NBD_BOUND flag when NBD connection is closed,
>     then the original NBD device could not be used again.
> 
> Signed-off-by: Medad <medadyoung@...il.com>

Tested on Witherspoon (OpenPOWER P9 with AST2500) and verified with
this patch that the NBD device could be disconnected/reconnected.

Tested by: Adriana Kobylak <anoo@...ux.ibm.com>

> ---
>  drivers/block/nbd.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> index 64278f4..5c88490 100644
> --- a/drivers/block/nbd.c
> +++ b/drivers/block/nbd.c
> @@ -277,10 +277,14 @@ static void sock_shutdown(struct nbd_device *nbd)
>  	struct nbd_config *config = nbd->config;
>  	int i;
> 
> -	if (config->num_connections == 0)
> +	if (config->num_connections == 0) {
> +		clear_bit(NBD_BOUND, &config->runtime_flags);
>  		return;
> -	if (test_and_set_bit(NBD_DISCONNECTED, &config->runtime_flags))
> +	}
> +	if (test_and_set_bit(NBD_DISCONNECTED, &config->runtime_flags)) {
> +		clear_bit(NBD_BOUND, &config->runtime_flags);
>  		return;
> +	}
> 
>  	for (i = 0; i < config->num_connections; i++) {
>  		struct nbd_sock *nsock = config->socks[i];
> @@ -944,7 +948,7 @@ static int nbd_reconnect_socket(struct nbd_device
> *nbd, unsigned long arg)
>  		sockfd_put(old);
> 
>  		clear_bit(NBD_DISCONNECTED, &config->runtime_flags);
> -
> +		clear_bit(NBD_BOUND, &config->runtime_flags);
>  		/* We take the tx_mutex in an error path in the recv_work, so we
>  		 * need to queue_work outside of the tx_mutex.
>  		 */
> @@ -1020,6 +1024,7 @@ static int nbd_disconnect(struct nbd_device *nbd)
>  	dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");
>  	set_bit(NBD_DISCONNECT_REQUESTED, &config->runtime_flags);
>  	send_disconnects(nbd);
> +	clear_bit(NBD_BOUND, &config->runtime_flags);
>  	return 0;
>  }