[dm-devel] [PATCH 5/6] devmapper: do not flush I/O for DM_DEVICE_CREATE

[Benjamin Marzinski]

On Wed, May 04, 2016 at 07:57:29AM +0200, Hannes Reinecke wrote:
> DM_DEVICE_CREATE loads a new table, so there cannot be any
> I/O pending. Hence we should be setting the 'no flush'
> and 'skip lockfs' flag to avoid delays during creation.

ACK

-Ben

> 
> Signed-off-by: Hannes Reinecke <hare at suse.de>
> ---
>  libmultipath/devmapper.c | 25 ++++++++++++++++---------
>  1 file changed, 16 insertions(+), 9 deletions(-)
> 
> diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c
> index 04dcb72..0ae72fc 100644
> --- a/libmultipath/devmapper.c
> +++ b/libmultipath/devmapper.c
> @@ -294,16 +294,23 @@ dm_addmap (int task, const char *target, struct multipath *mpp,
>  	if (ro)
>  		dm_task_set_ro(dmt);
>  
> -	if ((task == DM_DEVICE_CREATE) && strlen(mpp->wwid) > 0){
> -		prefixed_uuid = MALLOC(UUID_PREFIX_LEN + strlen(mpp->wwid) + 1);
> -		if (!prefixed_uuid) {
> -			condlog(0, "cannot create prefixed uuid : %s",
> -				strerror(errno));
> -			goto addout;
> +	if (task == DM_DEVICE_CREATE) {
> +		if (strlen(mpp->wwid) > 0) {
> +			prefixed_uuid = MALLOC(UUID_PREFIX_LEN +
> +					       strlen(mpp->wwid) + 1);
> +			if (!prefixed_uuid) {
> +				condlog(0, "cannot create prefixed uuid : %s",
> +					strerror(errno));
> +				goto addout;
> +			}
> +			sprintf(prefixed_uuid, UUID_PREFIX "%s", mpp->wwid);
> +			if (!dm_task_set_uuid(dmt, prefixed_uuid))
> +				goto freeout;
>  		}
> -		sprintf(prefixed_uuid, UUID_PREFIX "%s", mpp->wwid);
> -		if (!dm_task_set_uuid(dmt, prefixed_uuid))
> -			goto freeout;
> +		dm_task_skip_lockfs(dmt);
> +#ifdef LIBDM_API_FLUSH
> +		dm_task_no_flush(dmt);
> +#endif
>  	}
>  
>  	if (mpp->attribute_flags & (1 << ATTR_MODE) &&
> -- 
> 2.6.6