linux-kernel - Re: [PATCH] nfsd: have __write_ports_add/delxprt get/put lockd references for transports

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Date:	Thu, 17 Jun 2010 10:37:56 -0400
From:	Jeff Layton <jlayton@...hat.com>
To:	Jeff Layton <jlayton@...hat.com>
Cc:	bfields@...ldses.org, linux-nfs@...r.kernel.org,
	chris@...ne.freeserve.co.uk, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nfsd: have __write_ports_add/delxprt get/put lockd
 references for transports

On Thu, 17 Jun 2010 10:17:47 -0400
Jeff Layton <jlayton@...hat.com> wrote:

> nfsd_last_thread expects that any socket on sv_permsocks will hold a
> lockd reference. Make sure that __write_ports_addxprt takes a lockd
> reference for each socket it creates and have __write_ports_delxprt
> release references when it closes a socket.
> 
> Signed-off-by: Jeff Layton <jlayton@...hat.com>
> ---
>  fs/nfsd/nfsctl.c |   59 ++++++++++++++++++++++++++++++++++++++---------------
>  1 files changed, 42 insertions(+), 17 deletions(-)
> 
> diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> index 9e8645a..365aee0 100644
> --- a/fs/nfsd/nfsctl.c
> +++ b/fs/nfsd/nfsctl.c
> @@ -989,6 +989,21 @@ static ssize_t __write_ports_delfd(char *buf)
>  	return len;
>  }
>  
> +static int
> +nfsd_shutdown_xprt(const char *transport, const unsigned short family,
> +		     const int port)
> +{
> +	struct svc_xprt *xprt;
> +
> +	xprt = svc_find_xprt(nfsd_serv, transport, family, port);
> +	if (xprt == NULL)
> +		return -ENOTCONN;
> +
> +	svc_close_xprt(xprt);
> +	svc_xprt_put(xprt);
> +	return 0;
> +}
> +
>  /*
>   * A transport listener is added by writing it's transport name and
>   * a port number.
> @@ -996,7 +1011,6 @@ static ssize_t __write_ports_delfd(char *buf)
>  static ssize_t __write_ports_addxprt(char *buf)
>  {
>  	char transport[16];
> -	struct svc_xprt *xprt;
>  	int port, err;
>  
>  	if (sscanf(buf, "%15s %4u", transport, &port) != 2)
> @@ -1014,20 +1028,29 @@ static ssize_t __write_ports_addxprt(char *buf)
>  	if (err < 0)
>  		goto out_err;
>  
> +	err = lockd_up();
> +	if (err != 0) {
> +		nfsd_shutdown_xprt(transport, PF_INET, port);
> +		goto out_err;
> +	}
> +
>  	err = svc_create_xprt(nfsd_serv, transport,
>  				PF_INET6, port, SVC_SOCK_ANONYMOUS);
> -	if (err < 0 && err != -EAFNOSUPPORT)
> -		goto out_close;
> +	if (err < 0 && err != -EAFNOSUPPORT) {
> +		nfsd_shutdown_xprt(transport, PF_INET, port);
> +		goto out_err;
> +	}
> +
> +	err = lockd_up();
> +	if (err != 0) {
> +		nfsd_shutdown_xprt(transport, PF_INET6, port);
> +		nfsd_shutdown_xprt(transport, PF_INET, port);

Oops, I just realized I made a mistake here. We need to release the
lockd reference that was taken earlier here. Let me respin and I'll
resend...

> +		goto out_err;
> +	}
>  
>  	/* Decrease the count, but don't shut down the service */
>  	nfsd_serv->sv_nrthreads--;
>  	return 0;
> -out_close:
> -	xprt = svc_find_xprt(nfsd_serv, transport, PF_INET, port);
> -	if (xprt != NULL) {
> -		svc_close_xprt(xprt);
> -		svc_xprt_put(xprt);
> -	}
>  out_err:
>  	svc_destroy(nfsd_serv);
>  	return err;
> @@ -1039,9 +1062,8 @@ out_err:
>   */
>  static ssize_t __write_ports_delxprt(char *buf)
>  {
> -	struct svc_xprt *xprt;
>  	char transport[16];
> -	int port;
> +	int port, err;
>  
>  	if (sscanf(&buf[1], "%15s %4u", transport, &port) != 2)
>  		return -EINVAL;
> @@ -1049,13 +1071,16 @@ static ssize_t __write_ports_delxprt(char *buf)
>  	if (port < 1 || port > USHRT_MAX || nfsd_serv == NULL)
>  		return -EINVAL;
>  
> -	xprt = svc_find_xprt(nfsd_serv, transport, AF_UNSPEC, port);
> -	if (xprt == NULL)
> -		return -ENOTCONN;
> +	/* PF_INET6 sockets are considered optional */
> +	err = nfsd_shutdown_xprt(transport, PF_INET6, port);
> +	if (err == 0)
> +		lockd_down();
>  
> -	svc_close_xprt(xprt);
> -	svc_xprt_put(xprt);
> -	return 0;
> +	err = nfsd_shutdown_xprt(transport, PF_INET, port);
> +	if (err == 0)
> +		lockd_down();
> +
> +	return err;
>  }
>  
>  static ssize_t __write_ports(struct file *file, char *buf, size_t size)


-- 
Jeff Layton <jlayton@...hat.com>
--
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