tcm_vhost: Multi-target support

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.

Changes in v2:
- Handle non-contiguous tpgt

Changes in v3:
- Simplfy lock in vhost_scsi_set_endpoint
- Return -EEXIST when does not match

Signed-off-by: Asias He <asias@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

2 files changed, 85 insertions, 50 deletions

diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
index 704e4f674776..81ecda54b923 100644
--- a/drivers/vhost/tcm_vhost.c
+++ b/drivers/vhost/tcm_vhost.c
@@ -59,8 +59,14 @@ 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];
+        char vs_vhost_wwpn[TRANSPORT_IQN_LEN];
+        bool vs_endpoint;
+
         struct vhost_dev dev;
         struct vhost_virtqueue vqs[3];
 
@@ -564,10 +570,10 @@ 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;
+        u8 target;
 
         /* Must use ioctl VHOST_SCSI_SET_ENDPOINT */
-        tv_tpg = vs->vs_tpg;
-        if (unlikely(!tv_tpg))
+        if (unlikely(!vs->vs_endpoint))
                 return;
 
         mutex_lock(&vq->mutex);
@@ -635,6 +641,28 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs)
                         break;
                 }
 
+                /* Extract the tpgt */
+                target = v_req.lun[1];
+                tv_tpg = vs->vs_tpg[target];
+
+                /* Target does not exist, fail the request */
+                if (unlikely(!tv_tpg)) {
+                        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;
+                }
+
                 exp_data_len = 0;
                 for (i = 0; i < data_num; i++)
                         exp_data_len += vq->iov[data_first + i].iov_len;
@@ -743,7 +771,8 @@ static int vhost_scsi_set_endpoint(
 {
         struct tcm_vhost_tport *tv_tport;
         struct tcm_vhost_tpg *tv_tpg;
-        int index;
+        bool match = false;
+        int index, ret;
 
         mutex_lock(&vs->dev.mutex);
         /* Verify that ring has been setup correctly. */
@@ -754,7 +783,6 @@ static int vhost_scsi_set_endpoint(
                         return -EFAULT;
                 }
         }
-        mutex_unlock(&vs->dev.mutex);
 
         mutex_lock(&tcm_vhost_mutex);
         list_for_each_entry(tv_tpg, &tcm_vhost_list, tv_tpg_list) {
@@ -769,30 +797,33 @@ 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)) {
-                        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) {
-                                mutex_unlock(&vs->dev.mutex);
-                                mutex_lock(&tv_tpg->tv_tpg_mutex);
-                                tv_tpg->tv_tpg_vhost_count--;
+                if (!strcmp(tv_tport->tport_name, t->vhost_wwpn)) {
+                        if (vs->vs_tpg[tv_tpg->tport_tpgt]) {
                                 mutex_unlock(&tv_tpg->tv_tpg_mutex);
+                                mutex_unlock(&tcm_vhost_mutex);
+                                mutex_unlock(&vs->dev.mutex);
                                 return -EEXIST;
                         }
-
-                        vs->vs_tpg = tv_tpg;
+                        tv_tpg->tv_tpg_vhost_count++;
+                        vs->vs_tpg[tv_tpg->tport_tpgt] = tv_tpg;
                         smp_mb__after_atomic_inc();
-                        mutex_unlock(&vs->dev.mutex);
-                        return 0;
+                        match = true;
                 }
                 mutex_unlock(&tv_tpg->tv_tpg_mutex);
         }
         mutex_unlock(&tcm_vhost_mutex);
-        return -EINVAL;
+
+        if (match) {
+                memcpy(vs->vs_vhost_wwpn, t->vhost_wwpn,
+                       sizeof(vs->vs_vhost_wwpn));
+                vs->vs_endpoint = true;
+                ret = 0;
+        } else {
+                ret = -EEXIST;
+        }
+
+        mutex_unlock(&vs->dev.mutex);
+        return ret;
 }
 
 static int vhost_scsi_clear_endpoint(
@@ -801,7 +832,8 @@ static int vhost_scsi_clear_endpoint(
 {
         struct tcm_vhost_tport *tv_tport;
         struct tcm_vhost_tpg *tv_tpg;
-        int index, ret;
+        int index, ret, i;
+        u8 target;
 
         mutex_lock(&vs->dev.mutex);
         /* Verify that ring has been setup correctly. */
@@ -811,27 +843,32 @@ static int vhost_scsi_clear_endpoint(
                         goto err;
                 }
         }
+        for (i = 0; i < VHOST_SCSI_MAX_TARGET; i++) {
+                target = i;
 
-        if (!vs->vs_tpg) {
-                ret = -ENODEV;
-                goto err;
-        }
-        tv_tpg = vs->vs_tpg;
-        tv_tport = tv_tpg->tport;
-
-        if (strcmp(tv_tport->tport_name, t->vhost_wwpn) ||
-            (tv_tpg->tport_tpgt != t->vhost_tpgt)) {
-                pr_warn("tv_tport->tport_name: %s, tv_tpg->tport_tpgt: %hu"
-                        " does not match t->vhost_wwpn: %s, t->vhost_tpgt: %hu\n",
-                        tv_tport->tport_name, tv_tpg->tport_tpgt,
-                        t->vhost_wwpn, t->vhost_tpgt);
-                ret = -EINVAL;
-                goto err;
+                tv_tpg = vs->vs_tpg[target];
+                if (!tv_tpg)
+                        continue;
+
+                tv_tport = tv_tpg->tport;
+                if (!tv_tport) {
+                        ret = -ENODEV;
+                        goto err;
+                }
+
+                if (strcmp(tv_tport->tport_name, t->vhost_wwpn)) {
+                        pr_warn("tv_tport->tport_name: %s, tv_tpg->tport_tpgt: %hu"
+                                " does not match t->vhost_wwpn: %s, t->vhost_tpgt: %hu\n",
+                                tv_tport->tport_name, tv_tpg->tport_tpgt,
+                                t->vhost_wwpn, t->vhost_tpgt);
+                        ret = -EINVAL;
+                        goto err;
+                }
+                tv_tpg->tv_tpg_vhost_count--;
+                vs->vs_tpg[target] = NULL;
+                vs->vs_endpoint = false;
         }
-        tv_tpg->tv_tpg_vhost_count--;
-        vs->vs_tpg = NULL;
         mutex_unlock(&vs->dev.mutex);
-
         return 0;
 
 err:
@@ -866,16 +903,12 @@ static int vhost_scsi_open(struct inode *inode, struct file *f)
 static int vhost_scsi_release(struct inode *inode, struct file *f)
 {
         struct vhost_scsi *s = f->private_data;
+        struct vhost_scsi_target t;
 
-        if (s->vs_tpg && s->vs_tpg->tport) {
-                struct vhost_scsi_target backend;
-
-                memcpy(backend.vhost_wwpn, s->vs_tpg->tport->tport_name,
-                                sizeof(backend.vhost_wwpn));
-                backend.vhost_tpgt = s->vs_tpg->tport_tpgt;
-                vhost_scsi_clear_endpoint(s, &backend);
-        }
-
+        mutex_lock(&s->dev.mutex);
+        memcpy(t.vhost_wwpn, s->vs_vhost_wwpn, sizeof(t.vhost_wwpn));
+        mutex_unlock(&s->dev.mutex);
+        vhost_scsi_clear_endpoint(s, &t);
         vhost_dev_stop(&s->dev);
         vhost_dev_cleanup(&s->dev, false);
         kfree(s);
diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h
index 47ee80b3adee..519a5504d347 100644
--- a/drivers/vhost/tcm_vhost.h
+++ b/drivers/vhost/tcm_vhost.h
@@ -93,9 +93,11 @@ struct tcm_vhost_tport {
  *
  * ABI Rev 0: July 2012 version starting point for v3.6-rc merge candidate +
  *            RFC-v2 vhost-scsi userspace.  Add GET_ABI_VERSION ioctl usage
+ * ABI Rev 1: January 2013. Ignore vhost_tpgt filed in struct vhost_scsi_target.
+ *            All the targets under vhost_wwpn can be seen and used by guset.
  */
 
-#define VHOST_SCSI_ABI_VERSION  0
+#define VHOST_SCSI_ABI_VERSION  1
 
 struct vhost_scsi_target {
         int abi_version;