[PATCH] nvmet-passthru: Cleanup nvmet_passthru_map_sg()

[Logan Gunthorpe]

On 2020-10-15 1:56 a.m., Christoph Hellwig wrote:
> On Fri, Oct 09, 2020 at 05:18:16PM -0600, Logan Gunthorpe wrote:
>>  static int nvmet_passthru_map_sg(struct nvmet_req *req, struct request *rq)
>>  {
>> -	int sg_cnt = req->sg_cnt;
>>  	struct scatterlist *sg;
>>  	int op_flags = 0;
>>  	struct bio *bio;
>>  	int i, ret;
>>  
>> +	if (req->sg_cnt > BIO_MAX_PAGES)
>> +		return -EINVAL;
> 
> Don't you need to handle larger requests as well?  Or at least
> limit MDTS?

No and Yes: there is already code in nvmet_passthru_override_id_ctrl()
to limit MDTS based on max_segments and max_hw_sectors. So any request
that doesn't pass this check should be from a misbehaving client and an
error should be appropriate.

Logan