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Date: Fri, 10 May 2024 16:19:36 +0900
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Subject: Re: [PATCH v3 3/3] nvme: multipath: pr_notice when iopolicy changes
To: John Meneghini <jmeneghi@redhat.com>, tj@kernel.org,
 josef@toxicpanda.com, axboe@kernel.dk, kbusch@kernel.org, hch@lst.de,
 sagi@grimberg.me, emilne@redhat.com, hare@kernel.org
Cc: linux-block@vger.kernel.org, cgroups@vger.kernel.org,
 linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
 jrani@purestorage.com, randyj@purestorage.com, aviv.coro@ibm.com
References: <20240403141756.88233-1-hare@kernel.org>
 <20240509204324.832846-4-jmeneghi@redhat.com>
Content-Language: en-US
From: Damien Le Moal <dlemoal@kernel.org>
Organization: Western Digital Research
In-Reply-To: <20240509204324.832846-4-jmeneghi@redhat.com>
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On 5/10/24 05:43, John Meneghini wrote:
> Send a pr_notice when ever the iopolicy on a subsystem
> is changed. This is important for support reasons. It
> is fully expected that users will be changing the iopolicy
> with active IO in progress.
> 
> Signed-off-by: John Meneghini <jmeneghi@redhat.com>
> ---
>  drivers/nvme/host/multipath.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
> index e9330bb1990b..0286e44a081f 100644
> --- a/drivers/nvme/host/multipath.c
> +++ b/drivers/nvme/host/multipath.c
> @@ -67,6 +67,10 @@ static int nvme_activate_iopolicy(struct nvme_subsystem *subsys, int iopolicy)
>  		}
>  	}
>  	mutex_unlock(&subsys->lock);
> +
> +	pr_notice("%s: %s enable %d status %d for subsysnqn %s\n", __func__,
> +			nvme_iopolicy_names[iopolicy], enable, ret, subsys->subnqn);
> +
>  	return ret;
>  }
>  
> @@ -890,6 +894,8 @@ void nvme_subsys_iopolicy_update(struct nvme_subsystem *subsys, int iopolicy)
>  {
>  	struct nvme_ctrl *ctrl;
>  
> +	int old_iopolicy = READ_ONCE(subsys->iopolicy);

No need for the white line before this.

> +
>  	WRITE_ONCE(subsys->iopolicy, iopolicy);
>  
>  	mutex_lock(&nvme_subsystems_lock);
> @@ -898,6 +904,10 @@ void nvme_subsys_iopolicy_update(struct nvme_subsystem *subsys, int iopolicy)
>  		nvme_mpath_clear_ctrl_paths(ctrl);
>  	}
>  	mutex_unlock(&nvme_subsystems_lock);
> +
> +	pr_notice("%s: changed from %s to %s for subsysnqn %s\n", __func__,
> +			nvme_iopolicy_names[old_iopolicy], nvme_iopolicy_names[iopolicy],
> +			subsys->subnqn);

Using dev_notice(&subsys->dev, "...", ...); may be better. Same for the other
messages.

>  }
>  
>  static ssize_t nvme_subsys_iopolicy_store(struct device *dev,

-- 
Damien Le Moal
Western Digital Research