[PATCHv2] nvme: generate uevent once a multipath namespace is operational again

[Sagi Grimberg]

> In an all paths down scenario I/O will be requeued or aborted, so no
> further I/O will be ongoing on this namespace.
> This leaves upper layers like MD unable to determine if the namespace
> becomes operational again after a successful controller reset.
> This patch will send an uevent per multipathed namespace once the
> underlying controller is LIVE, allowing MD to start resync.
> 
> Changes to v1:
> - use disk_uevent() as suggested by hch
> 
> Signed-off-by: Hannes Reinecke <hare at suse.de>
> ---
>   drivers/nvme/host/multipath.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
> index 0551796517e6..ecc99bd5f8ad 100644
> --- a/drivers/nvme/host/multipath.c
> +++ b/drivers/nvme/host/multipath.c
> @@ -100,8 +100,11 @@ void nvme_kick_requeue_lists(struct nvme_ctrl *ctrl)
>   
>   	down_read(&ctrl->namespaces_rwsem);
>   	list_for_each_entry(ns, &ctrl->namespaces, list) {
> -		if (ns->head->disk)
> -			kblockd_schedule_work(&ns->head->requeue_work);
> +		if (!ns->head->disk)
> +			continue;
> +		kblockd_schedule_work(&ns->head->requeue_work);
> +		if (ctrl->state == NVME_CTRL_LIVE)
> +			disk_uevent(ns->head->disk, KOBJ_CHANGE);
>   	}
>   	up_read(&ctrl->namespaces_rwsem);
>   }

Why only for multipath namespaces though? This is not needed for 
non-multipath namespaces