Re: [PATCH 15/27] NSM: Add nsm_lookup() function

["J. Bruce Fields" <bfields@fieldses.org>]

On Fri, Dec 05, 2008 at 07:03:46PM -0500, Chuck Lever wrote:
> Introduce a new API to fs/lockd/mon.c that allows nlm_host_rebooted()
> to lookup up nsm_handles via the contents of an nlm_reboot struct.
> 
> The new function is equivalent to calling nsm_find() with @create set
> to zero, but it takes a struct nlm_reboot instead of separate
> arguments.

For next time: would prefer this combined with the following patch (on
the try-to-introduce-new-code-with-its-users principal), but OK for now;
applied.--b.

> 
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
> 
>  fs/lockd/mon.c              |   64 +++++++++++++++++++++++++++++++++++++++++++
>  include/linux/lockd/lockd.h |    1 +
>  2 files changed, 65 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/lockd/mon.c b/fs/lockd/mon.c
> index e0a799d..65fb904 100644
> --- a/fs/lockd/mon.c
> +++ b/fs/lockd/mon.c
> @@ -202,6 +202,29 @@ void nsm_unmonitor(const struct nlm_host *host)
>  	}
>  }
>  
> +static struct nsm_handle *nsm_lookup_hostname(const char *hostname,
> +					      const size_t len)
> +{
> +	struct nsm_handle *nsm;
> +
> +	list_for_each_entry(nsm, &nsm_handles, sm_link)
> +		if (strlen(nsm->sm_name) == len &&
> +		    memcmp(nsm->sm_name, hostname, len) == 0)
> +			return nsm;
> +	return NULL;
> +}
> +
> +static struct nsm_handle *nsm_lookup_priv(const struct nsm_private *priv)
> +{
> +	struct nsm_handle *nsm;
> +
> +	list_for_each_entry(nsm, &nsm_handles, sm_link)
> +		if (memcmp(nsm->sm_priv.data, priv->data,
> +					sizeof(priv->data)) == 0)
> +			return nsm;
> +	return NULL;
> +}
> +
>  /*
>   * Construct a unique cookie to match this nsm_handle to this monitored
>   * host.  It is passed to the local rpc.statd via NSMPROC_MON, and
> @@ -298,6 +321,47 @@ retry:
>  }
>  
>  /**
> + * nsm_reboot_lookup - match NLMPROC_SM_NOTIFY arguments to an nsm_handle
> + * @info: pointer to NLMPROC_SM_NOTIFY arguments
> + *
> + * Returns a matching nsm_handle if found in the nsm cache; the returned
> + * nsm_handle's reference count is bumped and sm_monitored is cleared.
> + * Otherwise returns NULL if some error occurred.
> + */
> +struct nsm_handle *nsm_reboot_lookup(const struct nlm_reboot *info)
> +{
> +	struct nsm_handle *cached;
> +
> +	spin_lock(&nsm_lock);
> +
> +	if (nsm_use_hostnames && info->mon != NULL)
> +		cached = nsm_lookup_hostname(info->mon, info->len);
> +	else
> +		cached = nsm_lookup_priv(&info->priv);
> +
> +	if (unlikely(cached == NULL)) {
> +		spin_unlock(&nsm_lock);
> +		dprintk("lockd: never saw rebooted peer '%.*s' before\n",
> +				info->len, info->mon);
> +		return cached;
> +	}
> +
> +	atomic_inc(&cached->sm_count);
> +	spin_unlock(&nsm_lock);
> +
> +	/*
> +	 * During subsequent lock activity, force a fresh
> +	 * notification to be set up for this host.
> +	 */
> +	cached->sm_monitored = 0;
> +
> +	dprintk("lockd: host %s (%s) rebooted, cnt %d\n",
> +			cached->sm_name, cached->sm_addrbuf,
> +			atomic_read(&cached->sm_count));
> +	return cached;
> +}
> +
> +/**
>   * nsm_release - Release an NSM handle
>   * @nsm: pointer to handle to be released
>   *
> diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
> index 2a3533e..5e3ad92 100644
> --- a/include/linux/lockd/lockd.h
> +++ b/include/linux/lockd/lockd.h
> @@ -251,6 +251,7 @@ struct nsm_handle *nsm_find(const struct sockaddr *sap, const size_t salen,
>  					const char *hostname,
>  					const size_t hostname_len,
>  					const int create);
> +struct nsm_handle *nsm_reboot_lookup(const struct nlm_reboot *info);
>  void		  nsm_release(struct nsm_handle *nsm);
>  
>  /*
>