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SubjectRe: [PATCH v1] virtio-scsi: get and set the queue limits for sg device


On Tue 21 Aug 2012 04:53:59 PM CST, Stefan Hajnoczi wrote:
> On Tue, Aug 21, 2012 at 9:26 AM, Cong Meng <mc@linux.vnet.ibm.com> wrote:
>> Each virtio scsi HBA has global request queue limits. But the passthrough
>> LUNs (scsi-generic) come from different host HBAs may have different request
>> queue limits. If the guest sends commands that exceed the host limits, the
>> commands will be rejected by host HAB.
>>
>> This patch addresses this issue by getting the per-LUN queue limits via the the
>> newly added virtio control request, then setting them properly.
>>
>> Signed-off-by: Cong Meng <mc@linux.vnet.ibm.com>
>> ---
>> drivers/scsi/virtio_scsi.c | 113 +++++++++++++++++++++++++++++++++++++------
>> include/linux/virtio_scsi.h | 18 +++++++
>> 2 files changed, 116 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
>> index 173cb39..ec5066f 100644
>> --- a/drivers/scsi/virtio_scsi.c
>> +++ b/drivers/scsi/virtio_scsi.c
>> @@ -35,12 +35,14 @@ struct virtio_scsi_cmd {
>> struct virtio_scsi_cmd_req cmd;
>> struct virtio_scsi_ctrl_tmf_req tmf;
>> struct virtio_scsi_ctrl_an_req an;
>> + struct virtio_scsi_ctrl_lq_req lq;
>> } req;
>> union {
>> struct virtio_scsi_cmd_resp cmd;
>> struct virtio_scsi_ctrl_tmf_resp tmf;
>> struct virtio_scsi_ctrl_an_resp an;
>> struct virtio_scsi_event evt;
>> + struct virtio_scsi_ctrl_lq_resp lq;
>> } resp;
>> } ____cacheline_aligned_in_smp;
>>
>> @@ -469,6 +471,46 @@ out:
>> return ret;
>> }
>>
>> +static u32 virtscsi_lun_query(struct scsi_device *sdev, u32 *value, u32 subtype)
>> +{
>> + struct Scsi_Host *shost = sdev->host;
>> + struct virtio_scsi *vscsi = shost_priv(shost);
>> + DECLARE_COMPLETION_ONSTACK(comp);
>> + struct virtio_scsi_cmd *cmd;
>> + struct virtio_scsi_target_state *tgt = vscsi->tgt[sdev->id];
>> + unsigned int ret = VIRTIO_SCSI_S_FAILURE;
>> +
>> + cmd = mempool_alloc(virtscsi_cmd_pool, GFP_ATOMIC);
>> + if (!cmd)
>> + goto out;
>> +
>> + memset(cmd, 0, sizeof(*cmd));
>> + cmd->comp = &comp;
>> + cmd->req.lq = (struct virtio_scsi_ctrl_lq_req){
>> + .type = VIRTIO_SCSI_T_LUN_QUERY,
>> + .subtype = subtype,
>> + .lun[0] = 1,
>> + .lun[1] = sdev->id,
>> + .lun[2] = (sdev->lun >> 8) | 0x40,
>> + .lun[3] = sdev->lun & 0xff,
>
> The LUN addressing code has been duplicated several times now. How
> about replacing it with something like

sure. I will include it.

Thnaks.
Cong.

>
> static void virtio_scsi_set_lun(u8 *lun, struct scsi_device *sdev)
> {
> lun[0] = 1;
> lun[1] = sdev->id;
> lun[2] = (sdev->lun >> 8) | 0x40;
> lun[3] = sdev->lun & 0xff;
> lun[4] = lun[5] = lun[6] = lun[7] = 0;
> }
>



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