[dm-devel] [PATCH v2 5/5] dm mpath: add ability to disable partition creation

[Chandra Seetharaman]

Reviewed-by: Chandra Seetharaman <sekharan at us.ibm.com>


On Tue, 2012-05-08 at 17:56 -0400, Mike Snitzer wrote:
> From: Hannes Reinecke <hare at suse.de>
> 
> When multipath devices are being used as disks for VM Guests any
> partition scanning / setup should be done within the VM Guest, not from
> host.  So we need to a mechanism to switch off partition scanning and
> creation via kpartx.
> 
> The new 'no_partitions' feature serves as a notifier to kpartx to _not_
> create partitions on these multipath devices.
> 
> Signed-off-by: Hannes Reinecke <hare at suse.de>
> Signed-off-by: Mike Snitzer <snitzer at redhat.com>
> ---
>  drivers/md/dm-mpath.c |   13 +++++++++++--
>  1 files changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
> index 0fc6849..1039e7f 100644
> --- a/drivers/md/dm-mpath.c
> +++ b/drivers/md/dm-mpath.c
> @@ -85,6 +85,7 @@ struct multipath {
>  	unsigned queue_if_no_path:1;	/* Queue I/O if last path fails? */
>  	unsigned saved_queue_if_no_path:1; /* Saved state during suspension */
>  	unsigned use_default_hw_handler:1; /* Use attached device handler */
> +	unsigned no_partitions:1;	/* Avoid partition scanning */
> 
>  	unsigned pg_init_retries;	/* Number of times to retry pg_init */
>  	unsigned pg_init_count;		/* Number of times pg_init called */
> @@ -770,7 +771,7 @@ static int parse_features(struct dm_arg_set *as, struct multipath *m)
>  	const char *arg_name;
> 
>  	static struct dm_arg _args[] = {
> -		{0, 6, "invalid number of feature args"},
> +		{0, 7, "invalid number of feature args"},
>  		{1, 50, "pg_init_retries must be between 1 and 50"},
>  		{0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
>  	};
> @@ -796,6 +797,11 @@ static int parse_features(struct dm_arg_set *as, struct multipath *m)
>  			continue;
>  		}
> 
> +		if (!strcasecmp(arg_name, "no_partitions")) {
> +			m->no_partitions = 1;
> +			continue;
> +		}
> +
>  		if (!strcasecmp(arg_name, "pg_init_retries") &&
>  		    (argc >= 1)) {
>  			r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
> @@ -1380,7 +1386,8 @@ static int multipath_status(struct dm_target *ti, status_type_t type,
>  		DMEMIT("%u ", m->queue_if_no_path +
>  			      (m->pg_init_retries > 0) * 2 +
>  			      (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
> -			      m->use_default_hw_handler);
> +			      m->use_default_hw_handler +
> +			      m->no_partitions);
>  		if (m->queue_if_no_path)
>  			DMEMIT("queue_if_no_path ");
>  		if (m->pg_init_retries)
> @@ -1389,6 +1396,8 @@ static int multipath_status(struct dm_target *ti, status_type_t type,
>  			DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
>  		if (m->use_default_hw_handler)
>  			DMEMIT("default_hw_handler ");
> +		if (m->no_partitions)
> +			DMEMIT("no_partitions ");
>  	}
> 
>  	if (!m->hw_handler_name || type == STATUSTYPE_INFO)