From 359eea71d98e7f2cf9efb5e65bb59a240bedb131 Mon Sep 17 00:00:00 2001
From: Fam Zheng <famz@redhat.com>
Date: Tue, 23 Sep 2014 15:49:27 +0800
Subject: [PATCH] virtio-scsi: Two stages processing of cmd request

Mechanical change, in preparation for bdrv_io_plug/bdrv_io_unplug.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/scsi/virtio-scsi-dataplane.c |  4 +++-
 hw/scsi/virtio-scsi.c           | 20 ++++++++++++--------
 include/hw/virtio/virtio-scsi.h |  3 ++-
 3 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
index acbf622ed8f2..11f570540727 100644
--- a/hw/scsi/virtio-scsi-dataplane.c
+++ b/hw/scsi/virtio-scsi-dataplane.c
@@ -126,7 +126,9 @@ static void virtio_scsi_iothread_handle_cmd(EventNotifier *notifier)
 
     event_notifier_test_and_clear(notifier);
     while ((req = virtio_scsi_pop_req_vring(s, vring))) {
-        virtio_scsi_handle_cmd_req(s, req);
+        if (virtio_scsi_handle_cmd_req_prepare(s, req)) {
+            virtio_scsi_handle_cmd_req_submit(s, req);
+        }
     }
 }
 
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 57efe656598a..6cf070f70ede 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -449,10 +449,9 @@ static void virtio_scsi_fail_cmd_req(VirtIOSCSIReq *req)
     virtio_scsi_complete_cmd_req(req);
 }
 
-void virtio_scsi_handle_cmd_req(VirtIOSCSI *s, VirtIOSCSIReq *req)
+bool virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req)
 {
     VirtIOSCSICommon *vs = &s->parent_obj;
-    int n;
     SCSIDevice *d;
     int rc;
 
@@ -464,14 +463,14 @@ void virtio_scsi_handle_cmd_req(VirtIOSCSI *s, VirtIOSCSIReq *req)
         } else {
             virtio_scsi_bad_req();
         }
-        return;
+        return false;
     }
 
     d = virtio_scsi_device_find(s, req->req.cmd.lun);
     if (!d) {
         req->resp.cmd.response = VIRTIO_SCSI_S_BAD_TARGET;
         virtio_scsi_complete_cmd_req(req);
-        return;
+        return false;
     }
     if (s->dataplane_started && bdrv_get_aio_context(d->conf.bs) != s->ctx) {
         aio_context_acquire(s->ctx);
@@ -487,11 +486,14 @@ void virtio_scsi_handle_cmd_req(VirtIOSCSI *s, VirtIOSCSIReq *req)
             req->sreq->cmd.xfer > req->qsgl.size)) {
         req->resp.cmd.response = VIRTIO_SCSI_S_OVERRUN;
         virtio_scsi_complete_cmd_req(req);
-        return;
+        return false;
     }
+    return true;
+}
 
-    n = scsi_req_enqueue(req->sreq);
-    if (n) {
+void virtio_scsi_handle_cmd_req_submit(VirtIOSCSI *s, VirtIOSCSIReq *req)
+{
+    if (scsi_req_enqueue(req->sreq)) {
         scsi_req_continue(req->sreq);
     }
 }
@@ -507,7 +509,9 @@ static void virtio_scsi_handle_cmd(VirtIODevice *vdev, VirtQueue *vq)
         return;
     }
     while ((req = virtio_scsi_pop_req(s, vq))) {
-        virtio_scsi_handle_cmd_req(s, req);
+        if (virtio_scsi_handle_cmd_req_prepare(s, req)) {
+            virtio_scsi_handle_cmd_req_submit(s, req);
+        }
     }
 }
 
diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
index 1a6a919960b0..1cc759a64402 100644
--- a/include/hw/virtio/virtio-scsi.h
+++ b/include/hw/virtio/virtio-scsi.h
@@ -256,7 +256,8 @@ void virtio_scsi_common_realize(DeviceState *dev, Error **errp,
 
 void virtio_scsi_common_unrealize(DeviceState *dev, Error **errp);
 void virtio_scsi_handle_ctrl_req(VirtIOSCSI *s, VirtIOSCSIReq *req);
-void virtio_scsi_handle_cmd_req(VirtIOSCSI *s, VirtIOSCSIReq *req);
+bool virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req);
+void virtio_scsi_handle_cmd_req_submit(VirtIOSCSI *s, VirtIOSCSIReq *req);
 VirtIOSCSIReq *virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq);
 void virtio_scsi_free_req(VirtIOSCSIReq *req);
 void virtio_scsi_push_event(VirtIOSCSI *s, SCSIDevice *dev,