Re: [PATCH] tcm_vhost: Multi-target support

[Asias He <asias@redhat.com>]

On 02/01/2013 04:59 AM, Nicholas A. Bellinger wrote:
> On Thu, 2013-01-31 at 17:28 +0800, Asias He wrote:
>> Hello Nicholas,
>>
>> On 01/31/2013 03:33 PM, Asias He wrote:
>>> In order to take advantages of Paolo's multi-queue virito-scsi, we need
>>> multi-target support in tcm_vhost first. Otherwise all the requests go
>>> to one queue and other queues are idle.
>>>
>>> This patch makes:
>>>
>>> 1. All the targets under the wwpn is seen and can be used by guest.
>>> 2. No need to pass the tpgt number in struct vhost_scsi_target to
>>>    tcm_vhost.ko. Only wwpn is needed.
>>> 3. We can always pass max_target = 255 to guest now, since we abort the
>>>    request who's target id does not exist.
>>>
>>> Signed-off-by: Asias He <asias@redhat.com>
>>> ---
>>>  drivers/vhost/tcm_vhost.c | 115 ++++++++++++++++++++++++++++------------------
>>>  drivers/vhost/tcm_vhost.h |   4 +-
>>>  2 files changed, 74 insertions(+), 45 deletions(-)
>>>
>>> diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
>>> index 218deb6..d50cb95 100644
>>> --- a/drivers/vhost/tcm_vhost.c
>>> +++ b/drivers/vhost/tcm_vhost.c
>>> @@ -59,13 +59,18 @@ enum {
>>>  	VHOST_SCSI_VQ_IO = 2,
>>>  };
>>>  
>>> +#define VHOST_SCSI_MAX_TARGET 256
>>> +
>>>  struct vhost_scsi {
>>> -	struct tcm_vhost_tpg *vs_tpg;	/* Protected by vhost_scsi->dev.mutex */
>>> +	/* Protected by vhost_scsi->dev.mutex */
>>> +	struct tcm_vhost_tpg *vs_tpg[VHOST_SCSI_MAX_TARGET];
>>>  	struct vhost_dev dev;
>>>  	struct vhost_virtqueue vqs[3];
>>>  
>>>  	struct vhost_work vs_completion_work; /* cmd completion work item */
>>>  	struct llist_head vs_completion_list; /* cmd completion queue */
>>> +	char vs_vhost_wwpn[TRANSPORT_IQN_LEN];
>>> +	int vs_num_target;
>>>  };
>>>  
>>>  /* Local pointer to allocated TCM configfs fabric module */
>>> @@ -564,13 +569,7 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs)
>>>  	u32 exp_data_len, data_first, data_num, data_direction;
>>>  	unsigned out, in, i;
>>>  	int head, ret;
>>> -
>>> -	/* Must use ioctl VHOST_SCSI_SET_ENDPOINT */
>>> -	tv_tpg = vs->vs_tpg;
>>> -	if (unlikely(!tv_tpg)) {
>>> -		pr_err("%s endpoint not set\n", __func__);
>>> -		return;
>>> -	}
>>> +	u8 target;
>>>  
>>>  	mutex_lock(&vq->mutex);
>>>  	vhost_disable_notify(&vs->dev, vq);
>>> @@ -637,6 +636,35 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs)
>>>  			break;
>>>  		}
>>>  
>>> +		/* Extract the tpgt */
>>> +		target = v_req.lun[1];
>>> +
>>> +		/* Target does not exit, fail the request */
>>> +		if (unlikely(target >= vs->vs_num_target)) {
>>> +			struct virtio_scsi_cmd_resp __user *resp;
>>> +			struct virtio_scsi_cmd_resp rsp;
>>> +
>>> +			memset(&rsp, 0, sizeof(rsp));
>>> +			rsp.response = VIRTIO_SCSI_S_BAD_TARGET;
>>> +			resp = vq->iov[out].iov_base;
>>> +			ret = copy_to_user(resp, &rsp, sizeof(rsp));
>>> +			if (!ret)
>>> +				vhost_add_used_and_signal(&vs->dev,
>>> +						&vs->vqs[2], head, 0);
>>> +			else
>>> +				pr_err("Faulted on virtio_scsi_cmd_resp\n");
>>> +
>>> +			continue;
>>> +		}
>>> +
>>> +		tv_tpg = vs->vs_tpg[target];
>>> +		if (unlikely(!tv_tpg)) {
>>> +			/* Must use ioctl VHOST_SCSI_SET_ENDPOINT */
>>> +			pr_err("endpoint not set, target = %d\n", target);
>>> +			vhost_discard_vq_desc(vq, 1);
>>> +			break;
>>> +		}
>>> +
>>>  		exp_data_len = 0;
>>>  		for (i = 0; i < data_num; i++)
>>>  			exp_data_len += vq->iov[data_first + i].iov_len;
>>> @@ -771,14 +799,11 @@ static int vhost_scsi_set_endpoint(
>>>  		}
>>>  		tv_tport = tv_tpg->tport;
>>>  
>>> -		if (!strcmp(tv_tport->tport_name, t->vhost_wwpn) &&
>>> -		    (tv_tpg->tport_tpgt == t->vhost_tpgt)) {
>>> +		if (!strcmp(tv_tport->tport_name, t->vhost_wwpn)) {
>>>  			tv_tpg->tv_tpg_vhost_count++;
>>> -			mutex_unlock(&tv_tpg->tv_tpg_mutex);
>>> -			mutex_unlock(&tcm_vhost_mutex);
>>>  
>>>  			mutex_lock(&vs->dev.mutex);
>>> -			if (vs->vs_tpg) {
>>> +			if (vs->vs_tpg[tv_tpg->tport_tpgt - 1]) {
>>>  				mutex_unlock(&vs->dev.mutex);
>>>  				mutex_lock(&tv_tpg->tv_tpg_mutex);
>>>  				tv_tpg->tv_tpg_vhost_count--;
>>> @@ -786,15 +811,17 @@ static int vhost_scsi_set_endpoint(
>>>  				return -EEXIST;
>>>  			}
>>>  
>>> -			vs->vs_tpg = tv_tpg;
>>> +			vs->vs_tpg[tv_tpg->tport_tpgt - 1] = tv_tpg;
>>
>>
>> tv_tpg->tport_tpgt starts from 0, right? I thought it starts from 1,
>> because I always got it starts from 1 in targetcli.
>>
>> o- vhost
>>    o- naa.6001405bd4e8476d
>>       o- tpg1
>>          o- luns
>>             o- lun0
>>       o- tpg2
>>          o- luns
>>             o- lun0
>>       o- tpg3
>>          o- luns
>>             o- lun0
>>       o- tpg4
>>          o- luns
>>             o- lun0
>>
> 
> So at least with iscsi-target, we start from tpgt=1 to avoid some legacy
> initiators that have issues handling tgpt=0.
> 
> Given that rtslib/targetcli currently expect this with the "tpgs"
> feature is enabled, starting from tpgt=1 with tcm_vhost probably makes
> the most sense.

Okay. But tgpt can be 0, right?

I saw this setup:

  cd /sys/kernel/config/target
  mkdir -p core/fileio_0/fileio
  echo 'fd_dev_name=/home/pbonzini/test.img,fd_dev_size=5905580032' >
core/fileio_0/fileio/control
  echo 1 > core/fileio_0/fileio/enable
  mkdir -p vhost/naa.600140554cf3a18e/tpgt_0/lun/lun_0
  cd vhost/naa.600140554cf3a18e/tpgt_0
  ln -sf ../../../../../core/fileio_0/fileio/ lun/lun_0/virtual_scsi_port
  echo naa.60014053226f0388 > nexus

And this:

       ** Setup wwpn and tpgt
       $ wwpn="naa.0"
       $ tpgt=/sys/kernel/config/target/vhost/$wwpn/tpgt_0
       $ nexus=$tpgt/nexus
       $ mkdir -p $tpgt
       $ echo -n $wwpn > $nexus



>> If it is true. I will cook v2 of this patch.
>>
>> Also, the tv_tpg->tport_tpgt can be none-continuous. e.g.
>>
>> o- vhost
>>    o- naa.6001405bd4e8476d
>>       o- tpg1
>>          o- luns
>>             o- lun0
>>       o- tpg2
>>          o- luns
>>             o- lun0
>>       o- tpg4
>>          o- luns
>>             o- lun0
>>
>> I will handle this in v2.
>>
> 
> Correct, tpgt values may be optionally non-contiguous up to unsigned
> short.

ok.

> --nab
> 
> 


-- 
Asias