[PATCH 1/2] nvme: skip namespaces which are about to be removed

[edmund.nadolski@intel.com (Nadolski, Edmund)]

On 8/1/2019 1:16 AM, Hannes Reinecke wrote:
> nvme_ns_remove() will only remove the namespaces from the list at
> the very last step, so we might run into situations where we iterate
> over namespaces which are about to be deleted.
> To avoid crashes we should be skipping all namespaces with the
> NVME_NS_REMOVING flag set.
> 
> Signed-off-by: Hannes Reinecke <hare at suse.com>
> ---
>   drivers/nvme/host/core.c | 19 ++++++++++++++++++-
>   1 file changed, 18 insertions(+), 1 deletion(-)
> 

LGTM, just a (probably lame) question: is the check also needed in
nvme_[start|stop|sync]_queues()?

Ed

> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index fcfff0a17a17..177fa4185775 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -1303,9 +1303,12 @@ static void nvme_update_formats(struct nvme_ctrl *ctrl)
>   	struct nvme_ns *ns;
>   
>   	down_read(&ctrl->namespaces_rwsem);
> -	list_for_each_entry(ns, &ctrl->namespaces, list)
> +	list_for_each_entry(ns, &ctrl->namespaces, list) {
> +		if (test_bit(NVME_NS_REMOVING, &ns->flags))
> +			continue;
>   		if (ns->disk && nvme_revalidate_disk(ns->disk))
>   			nvme_set_queue_dying(ns);
> +	}
>   	up_read(&ctrl->namespaces_rwsem);
>   
>   	nvme_remove_invalid_namespaces(ctrl, NVME_NSID_ALL);
> @@ -1698,6 +1701,10 @@ static void __nvme_revalidate_disk(struct gendisk *disk, struct nvme_id_ns *id)
>   {
>   	struct nvme_ns *ns = disk->private_data;
>   
> +	/* if ns is removing we cannot mangle with the request queue */
> +	if (test_bit(NVME_NS_REMOVING, &ns->flags))
> +		return;
> +
>   	/*
>   	 * If identify namespace failed, use default 512 byte block size so
>   	 * block layer can use before failing read/write for 0 capacity.
> @@ -2776,6 +2783,10 @@ static int nvme_dev_user_cmd(struct nvme_ctrl *ctrl, void __user *argp)
>   		ret = -EINVAL;
>   		goto out_unlock;
>   	}
> +	if (test_bit(NVME_NS_REMOVING, &ns->flags)) {
> +		ret = -ENODEV;
> +		goto out_unlock;
> +	}
>   
>   	dev_warn(ctrl->device,
>   		"using deprecated NVME_IOCTL_IO_CMD ioctl on the char device!\n");
> @@ -3255,6 +3266,10 @@ static struct nvme_ns *nvme_find_get_ns(struct nvme_ctrl *ctrl, unsigned nsid)
>   		if (ns->head->ns_id == nsid) {
>   			if (!kref_get_unless_zero(&ns->kref))
>   				continue;
> +			if (test_bit(NVME_NS_REMOVING, &ns->flags)) {
> +				nvme_put_ns(ns);
> +				continue;
> +			}
>   			ret = ns;
>   			break;
>   		}
> @@ -3445,6 +3460,8 @@ static void nvme_remove_invalid_namespaces(struct nvme_ctrl *ctrl,
>   
>   	down_write(&ctrl->namespaces_rwsem);
>   	list_for_each_entry_safe(ns, next, &ctrl->namespaces, list) {
> +		if (test_bit(NVME_NS_REMOVING, &ns->flags))
> +			continue;
>   		if (ns->head->ns_id > nsid || test_bit(NVME_NS_DEAD, &ns->flags))
>   			list_move_tail(&ns->list, &rm_list);
>   	}
>