Re: [PATCH 10/20] nvme: freeze the queue over ->lba_shift updates

From: Sagi Grimberg <sagi@grimberg.me>
To: Christoph Hellwig <hch@lst.de>, linux-nvme@lists.infradead.org
Cc: Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@kernel.dk>,
	Damien Le Moal <Damien.LeMoal@wdc.com>
Subject: Re: [PATCH 10/20] nvme: freeze the queue over ->lba_shift updates
Date: Tue, 29 Sep 2020 01:48:03 -0700	[thread overview]
Message-ID: <39b98188-2803-2f49-e225-8d3fbe3bfb1f@grimberg.me> (raw)
In-Reply-To: <20200928123502.435373-11-hch@lst.de>

> Ensure that there can't be any I/O in flight went we change the disk
> geometry in nvme_update_ns_info, most notable the LBA size by lifting
> the queue free from nvme_update_disk_info into the caller

The queue is frozen on the queue logical block size, why should
we care about I/O while ns->lba_shift?

> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   drivers/nvme/host/core.c | 20 ++++++++++++++------
>   1 file changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 443aba9c9fdd11..82cd03c0ba21ba 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -2021,7 +2021,7 @@ static void nvme_update_disk_info(struct gendisk *disk,
>   		/* unsupported block size, set capacity to 0 later */
>   		bs = (1 << 9);
>   	}
> -	blk_mq_freeze_queue(disk->queue);
> +
>   	blk_integrity_unregister(disk);
>   
>   	atomic_bs = phys_bs = bs;
> @@ -2086,8 +2086,6 @@ static void nvme_update_disk_info(struct gendisk *disk,
>   		set_disk_ro(disk, true);
>   	else
>   		set_disk_ro(disk, false);
> -
> -	blk_mq_unfreeze_queue(disk->queue);
>   }
>   
>   static inline bool nvme_first_scan(struct gendisk *disk)
> @@ -2133,6 +2131,7 @@ static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_id_ns *id)
>   	struct nvme_ctrl *ctrl = ns->ctrl;
>   	int ret;
>   
> +	blk_mq_freeze_queue(ns->disk->queue);
>   	/*
>   	 * If identify namespace failed, use default 512 byte block size so
>   	 * block layer can use before failing read/write for 0 capacity.
> @@ -2150,30 +2149,39 @@ static int nvme_update_ns_info(struct nvme_ns *ns, struct nvme_id_ns *id)
>   			dev_warn(ctrl->device,
>   				"failed to add zoned namespace:%u ret:%d\n",
>   				ns->head->ns_id, ret);
> -			return ret;
> +			goto out_unfreeze;
>   		}
>   		break;
>   	default:
>   		dev_warn(ctrl->device, "unknown csi:%u ns:%u\n",
>   			ns->head->ids.csi, ns->head->ns_id);
> -		return -ENODEV;
> +		ret = -ENODEV;
> +		goto out_unfreeze;
>   	}
>   
>   	ret = nvme_configure_metadata(ns, id);
>   	if (ret)
> -		return ret;
> +		goto out_unfreeze;
>   	nvme_set_chunk_sectors(ns, id);
>   	nvme_update_disk_info(ns->disk, ns, id);
> +	blk_mq_unfreeze_queue(ns->disk->queue);
> +
>   #ifdef CONFIG_NVME_MULTIPATH
>   	if (ns->head->disk) {
> +		blk_mq_freeze_queue(ns->head->disk->queue);
>   		nvme_update_disk_info(ns->head->disk, ns, id);
>   		blk_stack_limits(&ns->head->disk->queue->limits,
>   				 &ns->queue->limits, 0);
>   		blk_queue_update_readahead(ns->head->disk->queue);
>   		nvme_update_bdev_size(ns->head->disk);
> +		blk_mq_unfreeze_queue(ns->head->disk->queue);
>   	}
>   #endif
>   	return 0;
> +
> +out_unfreeze:
> +	blk_mq_unfreeze_queue(ns->disk->queue);
> +	return ret;
>   }
>   
>   static int nvme_validate_ns(struct nvme_ns *ns)
> 

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