Re: [PATCH 3/3] nvme: change the interface between nvme and lightnvm

["Matias Bjørling" <mb@lightnvm.io>]

On 11/25/2015 01:42 PM, Wenwei Tao wrote:
> When nvme devices were removed, we need to handle the targets
> build upon them properly: remove the existing targets, block
> creations of new ones. To do this clean up job well, we
> need to change the interface between nvme and lightnvm.
>
> Signed-off-by: Wenwei Tao <ww.tao0320@gmail.com>
> ---
>   drivers/nvme/host/lightnvm.c | 17 ++++++++++++++++-
>   drivers/nvme/host/nvme.h     |  1 +
>   drivers/nvme/host/pci.c      | 10 ++++++----
>   3 files changed, 23 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/nvme/host/lightnvm.c b/drivers/nvme/host/lightnvm.c
> index e0b7b95..3f4ffb7 100644
> --- a/drivers/nvme/host/lightnvm.c
> +++ b/drivers/nvme/host/lightnvm.c
> @@ -468,6 +468,14 @@ static void nvme_nvm_dev_dma_free(void *pool, void *ppa_list,
>   	dma_pool_free(pool, ppa_list, dma_handler);
>   }
>
> +static void nvme_nvm_dev_remove(struct request_queue *q)
> +{
> +	struct nvme_ns *ns = q->queuedata;
> +
> +	kref_put(&ns->kref, nvme_free_ns);
> +
> +}
> +
>   static struct nvm_dev_ops nvme_nvm_dev_ops = {
>   	.identity		= nvme_nvm_identity,
>
> @@ -482,13 +490,20 @@ static struct nvm_dev_ops nvme_nvm_dev_ops = {
>   	.destroy_dma_pool	= nvme_nvm_destroy_dma_pool,
>   	.dev_dma_alloc		= nvme_nvm_dev_dma_alloc,
>   	.dev_dma_free		= nvme_nvm_dev_dma_free,
> +	.dev_remove		= nvme_nvm_dev_remove,
>
>   	.max_phys_sect		= 64,
>   };
>
>   int nvme_nvm_register(struct request_queue *q, char *disk_name)
>   {
> -	return nvm_register(q, disk_name, &nvme_nvm_dev_ops);
> +	int ret;
> +	struct nvme_ns *ns = q->queuedata;
> +
> +	ret = nvm_register(q, disk_name, &nvme_nvm_dev_ops);
> +	if (!ret)
> +		kref_get(&ns->kref);
> +	return ret;
>   }
>
>   void nvme_nvm_unregister(struct request_queue *q, char *disk_name)
> diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
> index fdb4e5b..251ec9d 100644
> --- a/drivers/nvme/host/nvme.h
> +++ b/drivers/nvme/host/nvme.h
> @@ -116,6 +116,7 @@ static inline u64 nvme_block_nr(struct nvme_ns *ns, sector_t sector)
>   	return (sector >> (ns->lba_shift - 9));
>   }
>
> +void nvme_free_ns(struct kref *kref);
>   int nvme_submit_sync_cmd(struct request_queue *q, struct nvme_command *cmd,
>   		void *buf, unsigned bufflen);
>   int __nvme_submit_sync_cmd(struct request_queue *q, struct nvme_command *cmd,
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 8187df2..f63223d 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -1960,13 +1960,10 @@ static int nvme_compat_ioctl(struct block_device *bdev, fmode_t mode,
>   #endif
>
>   static void nvme_free_dev(struct kref *kref);
> -static void nvme_free_ns(struct kref *kref)
> +void nvme_free_ns(struct kref *kref)
>   {
>   	struct nvme_ns *ns = container_of(kref, struct nvme_ns, kref);
>
> -	if (ns->type == NVME_NS_LIGHTNVM)
> -		nvme_nvm_unregister(ns->queue, ns->disk->disk_name);
> -
>   	spin_lock(&dev_list_lock);
>   	ns->disk->private_data = NULL;
>   	spin_unlock(&dev_list_lock);
> @@ -2533,6 +2530,11 @@ static void nvme_ns_remove(struct nvme_ns *ns)
>   {
>   	bool kill = nvme_io_incapable(ns->dev) && !blk_queue_dying(ns->queue);
>
> +	if (ns->type == NVME_NS_LIGHTNVM) {
> +		nvme_nvm_unregister(ns->queue, ns->disk->disk_name);
> +		ns->type = 0;

Do we need to set it to zero, since we won't use it after its been removed?

> +	}
> +
>   	if (kill)
>   		blk_set_queue_dying(ns->queue);
>   	if (ns->disk->flags & GENHD_FL_UP)
>