[Ocfs2-tools-devel] [PATCH 2/2] libo2cb: Adds support for global heartbeat

[Joel Becker]

On Thu, Dec 16, 2010 at 02:14:06PM -0800, Sunil Mushran wrote:
> Add support for global heartbeat in libo2cb. This patch adds functions
> to start and stop global heartbeat, toggle between global and local heartbeat,
> list active heartbeats, etc. The functionality added does not modify the
> semantics of the local heartbeat mode.
> 
> Signed-off-by: Sunil Mushran <sunil.mushran at oracle.com>
> ---
>  include/o2cb/o2cb.h |   12 ++++
>  libo2cb/o2cb_abi.c  |  181 +++++++++++++++++++++++++++++++++++++++++++-------
>  libo2cb/o2cb_abi.h  |    1 +
>  3 files changed, 168 insertions(+), 26 deletions(-)
> 
> diff --git a/include/o2cb/o2cb.h b/include/o2cb/o2cb.h
> index 4f8bcae..8526ad7 100644
> --- a/include/o2cb/o2cb.h
> +++ b/include/o2cb/o2cb.h
> @@ -71,6 +71,12 @@ void o2cb_free_cluster_list(char **clusters);
>  errcode_t o2cb_list_nodes(char *cluster_name, char ***nodes);
>  void o2cb_free_nodes_list(char **nodes);
>  
> +errcode_t o2cb_list_hb_regions(char *cluster_name, char ***regions);
> +void o2cb_free_hb_regions_list(char **regions);
> +
> +errcode_t o2cb_global_heartbeat_mode(char *cluster_name, int *global);
> +errcode_t o2cb_set_heartbeat_mode(char *cluster_name, char *mode);
> +
>  errcode_t o2cb_control_daemon_debug(char **debug);
>  
>  struct o2cb_cluster_desc {
> @@ -95,6 +101,12 @@ struct o2cb_region_desc {
>   * begin_group_join().  Regular programs (not mount.ocfs2) should provide
>   * a mountpoint that does not begin with a '/'.  Eg, fsck could use "fsck"
>   */
> +errcode_t o2cb_start_heartbeat(struct o2cb_cluster_desc *cluster,
> +			       struct o2cb_region_desc *region);
> +
> +errcode_t o2cb_stop_heartbeat(struct o2cb_cluster_desc *cluster,
> +			      struct o2cb_region_desc *region);
> +
>  errcode_t o2cb_begin_group_join(struct o2cb_cluster_desc *cluster,
>  				struct o2cb_region_desc *region);
>  errcode_t o2cb_complete_group_join(struct o2cb_cluster_desc *cluster,
> diff --git a/libo2cb/o2cb_abi.c b/libo2cb/o2cb_abi.c
> index e2f2f3f..df069d1 100644
> --- a/libo2cb/o2cb_abi.c
> +++ b/libo2cb/o2cb_abi.c
> @@ -1193,13 +1193,46 @@ out:
>  	return err;
>  }
>  
> -/* For ref counting purposes, we need to know whether this process
> - * called o2cb_create_heartbeat_region_disk. If it did, then we want
> - * to drop the reference taken during startup, otherwise that
> - * reference was dropped automatically at process shutdown so there's
> - * no need to drop one here. */
> -static errcode_t classic_group_leave(struct o2cb_cluster_desc *cluster,
> -				     struct o2cb_region_desc *region)
> +errcode_t o2cb_start_heartbeat(struct o2cb_cluster_desc *cluster,
> +			       struct o2cb_region_desc *region)
> +{
> +	errcode_t ret, up_ret;
> +	int semid, global = 0;
> +
> +	ret = o2cb_mutex_down_lookup(region->r_name, &semid);
> +	if (ret)
> +		return ret;
> +
> +	ret = o2cb_global_heartbeat_mode(cluster->c_cluster, &global);
> +	if (ret)
> +		goto up;
> +
> +	ret = o2cb_create_heartbeat_region(cluster->c_cluster,
> +					   region->r_name,
> +					   region->r_device_name,
> +					   region->r_block_bytes,
> +					   region->r_start_block,
> +					   region->r_blocks);
> +	if (ret && ret != O2CB_ET_REGION_EXISTS)
> +		goto up;
> +
> +	if (global && ret == O2CB_ET_REGION_EXISTS) {
> +		ret = 0;
> +		goto up;
> +	}
> +
> +	ret = __o2cb_get_ref(semid, !region->r_persist);
> +	/* XXX: Maybe stop heartbeat on error here? */
> +up:
> +	up_ret = o2cb_mutex_up(semid);
> +	if (up_ret && !ret)
> +		ret = up_ret;
> +
> +	return ret;
> +}
> +
> +errcode_t o2cb_stop_heartbeat(struct o2cb_cluster_desc *cluster,
> +			      struct o2cb_region_desc *region)
>  {
>  	errcode_t ret, up_ret;
>  	int hb_refs;
> @@ -1247,34 +1280,45 @@ up:
>  
>  done:
>  	return ret;
> +
> +}
> +
> +/* For ref counting purposes, we need to know whether this process
> + * called o2cb_create_heartbeat_region_disk. If it did, then we want
> + * to drop the reference taken during startup, otherwise that
> + * reference was dropped automatically at process shutdown so there's
> + * no need to drop one here. */
> +static errcode_t classic_group_leave(struct o2cb_cluster_desc *cluster,
> +				     struct o2cb_region_desc *region)
> +{
> +	errcode_t ret;
> +	int global = 0;
> +
> +	ret = o2cb_global_heartbeat_mode(cluster->c_cluster, &global);
> +	if (ret)
> +		goto bail;
> +
> +	if (!global)
> +		ret = o2cb_stop_heartbeat(cluster, region);
> +
> +bail:
> +	return ret;
>  }
>  
>  static errcode_t classic_begin_group_join(struct o2cb_cluster_desc *cluster,
>  					  struct o2cb_region_desc *region)
>  {
> -	errcode_t ret, up_ret;
> -	int semid;
> +	errcode_t ret;
> +	int global = 0;
>  
> -	ret = o2cb_mutex_down_lookup(region->r_name, &semid);
> +	ret = o2cb_global_heartbeat_mode(cluster->c_cluster, &global);
>  	if (ret)
> -		return ret;
> +		goto bail;
>  
> -	ret = o2cb_create_heartbeat_region(cluster->c_cluster,
> -					   region->r_name,
> -					   region->r_device_name,
> -					   region->r_block_bytes,
> -					   region->r_start_block,
> -					   region->r_blocks);
> -	if (ret && ret != O2CB_ET_REGION_EXISTS)
> -		goto up;
> -
> -	ret = __o2cb_get_ref(semid, !region->r_persist);
> -	/* XXX: Maybe stop heartbeat on error here? */
> -up:
> -	up_ret = o2cb_mutex_up(semid);
> -	if (up_ret && !ret)
> -		ret = up_ret;
> +	if (!global)
> +		ret = o2cb_start_heartbeat(cluster, region);
>  
> +bail:
>  	return ret;
>  }
>  
> @@ -1934,6 +1978,91 @@ void o2cb_free_nodes_list(char **nodes)
>  	o2cb_free_dir_list(nodes);
>  }
>  
> +errcode_t o2cb_list_hb_regions(char *cluster_name, char ***regions)
> +{
> +	char path[PATH_MAX];
> +	errcode_t ret;
> +
> +	if (configfs_path == NULL)
> +		return O2CB_ET_SERVICE_UNAVAILABLE;
> +
> +	ret = snprintf(path, PATH_MAX - 1, O2CB_FORMAT_HEARTBEAT_DIR,
> +		       configfs_path, cluster_name);
> +	if ((ret <= 0) || (ret == (PATH_MAX - 1)))
> +		return O2CB_ET_INTERNAL_FAILURE;
> +
> +	return o2cb_list_dir(path, regions);
> +}
> +
> +void o2cb_free_hb_regions_list(char **regions)
> +{
> +	o2cb_free_dir_list(regions);
> +}
> +
> +errcode_t o2cb_global_heartbeat_mode(char *cluster_name, int *global)
> +{
> +	char attr_path[PATH_MAX];
> +	char _fake_cluster_name[NAME_MAX];
> +	char attr_value[16];
> +	errcode_t ret;
> +
> +	if (!cluster_name) {
> +		ret = _fake_default_cluster(_fake_cluster_name);
> +		if (ret)
> +			return ret;
> +		cluster_name = _fake_cluster_name;
> +	}
> +
> +	ret = snprintf(attr_path, PATH_MAX - 1, O2CB_FORMAT_HEARTBEAT_MODE,
> +		       configfs_path, cluster_name);
> +	if ((ret <= 0) || (ret == (PATH_MAX - 1)))
> +		return O2CB_ET_INTERNAL_FAILURE;
> +
> +	*global = 0;
> +
> +	ret = o2cb_get_attribute(attr_path, attr_value, sizeof(attr_value) - 1);
> +	if (ret) {
> +		if (ret == O2CB_ET_SERVICE_UNAVAILABLE)
> +			ret = 0;
> +		return ret;
> +	}
> +
> +	/* wipeout the last newline character */
> +	do_strchomp(attr_value);

	Still not using tools_strchomp()?  Everything else looks good.

Joel


-- 

"The nearest approach to immortality on Earth is a government
 bureau."
	- James F. Byrnes

Joel Becker
Senior Development Manager
Oracle
E-mail: joel.becker at oracle.com
Phone: (650) 506-8127