[dm-devel] [PATCH 01/12] libmultipath: add wwid for "struct uevent" to record wwid of uevent

[Benjamin Marzinski]

On Tue, Dec 27, 2016 at 04:03:18PM +0800, tang.junhui at zte.com.cn wrote:
> From: tang.junhui <tang.junhui at zte.com.cn>
> 
> Add "char *wwid" to point WWID of uevent. This member identifies
> the LUN ID which the path belongs to, and it is used for merging
> uevents. WWID possibly did not exist in uevent yet, so ->wwid
> would be NULL, those uevents would not be merged, but be proccessed
> as old way.

Right now, multipath users are allowed configure devices to set the wwid
based on any udev environment variable (or even use a callout, although
this is deprecated). With this patch, that breaks. If the udev sets
ID_SERIAL for a device, that is its wwid, right?  Do you know if rbd
devices have ID_SERIAL set? If so, this change will break them.  Even if
this change doesn't break any devices in their default configurations,
we would need to disallow changing how the wwid is set for this patch
to be safe.

-Ben 

> 
> Change-Id: Ie6b076363b3735dc7de10184b27fa799b499af0e
> Signed-off-by: tang.junhui <tang.junhui at zte.com.cn>
> ---
>  libmultipath/uevent.c | 2 ++
>  libmultipath/uevent.h | 1 +
>  2 files changed, 3 insertions(+)
> 
> diff --git a/libmultipath/uevent.c b/libmultipath/uevent.c
> index 7edcce1..ef1bafe 100644
> --- a/libmultipath/uevent.c
> +++ b/libmultipath/uevent.c
> @@ -424,6 +424,8 @@ struct uevent *uevent_from_udev_device(struct udev_device *dev)
>  			uev->devpath = uev->envp[i] + 8;
>  		if (strcmp(name, "ACTION") == 0)
>  			uev->action = uev->envp[i] + 7;
> +		if (strcmp(name, "ID_SERIAL") == 0)
> +			uev->wwid = uev->envp[i] + 10;
>  		i++;
>  		if (i == HOTPLUG_NUM_ENVP - 1)
>  			break;
> diff --git a/libmultipath/uevent.h b/libmultipath/uevent.h
> index 9d22dcd..7bfccef 100644
> --- a/libmultipath/uevent.h
> +++ b/libmultipath/uevent.h
> @@ -22,6 +22,7 @@ struct uevent {
>  	char *devpath;
>  	char *action;
>  	char *kernel;
> +	char *wwid;
>  	unsigned long seqnum;
>  	char *envp[HOTPLUG_NUM_ENVP];
>  };
> -- 
> 2.8.1.windows.1
>