[PATCH v2] nvme: check if the namespace supports metadata in nvme_map_user_request()

[Puranjay Mohan]

Keith Busch <kbusch at kernel.org> writes:

> On Tue, Aug 27, 2024 at 01:23:27PM +0000, Puranjay Mohan wrote:
>> @@ -119,9 +120,13 @@ static int nvme_map_user_request(struct request *req, u64 ubuffer,
>>  	struct request_queue *q = req->q;
>>  	struct nvme_ns *ns = q->queuedata;
>>  	struct block_device *bdev = ns ? ns->disk->part0 : NULL;
>> +	bool has_metadata = bdev && meta_buffer && meta_len;
>
> If this is an admin command, then bdev is NULL, so "has_metadata" is
> false.
>
>>  	struct bio *bio = NULL;
>>  	int ret;
>>  
>> +	if (has_metadata && !blk_get_integrity(bdev->bd_disk))
>> +		return -EINVAL;
>> +
>
> Since has_metadata is false, we continue on to process this admin
> command, but ignore the user's metadata settings. Do we want to return
> error there too?

As an admin command with metadata is an invalid configuration, we can
ignore the metada and go ahead with the admin command or I can add the
following after the above check:

	if (!bdev && (meta_buffer || meta_len))
    	return -EINVAL;

I don't know what is the best approach here.

Thanks,
Puranjay