[Qemu-devel] [PATCH 1/3] scsi/virtio-scsi: Properly flush I/Os inflight during an unplug

[Eric Farman <farman@linux.vnet.ibm.com>]

When an unplug is triggered via QMP, the routine scsi_req_cancel
is called to cancel any outstanding requests.  However, the I/Os
themselves were instantiated via an asynchronous call that will
drive scsi_*_complete routines after the unplug call stack finishes.
As all references to the request have been released by the cancel
thread, the scsi_*_complete routines experience a range of failures
when it attempts to manipulate the released storage.

Before we exit back to scsi_req_cancel, we need to inform the
asynchronous tasks that they were canceled.  This will handle all
the cleanup work performed by scsi_*_complete before we release
all the references to the affected request(s).

Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
---
 hw/scsi/virtio-scsi.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 6dcdd1b..a8fde04 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -339,6 +339,7 @@ static void virtio_scsi_request_cancelled(SCSIRequest *r)
         req->resp.cmd->response = VIRTIO_SCSI_S_ABORTED;
     }
     virtio_scsi_complete_req(req);
+    bdrv_drain_all();
 }
 
 static void virtio_scsi_fail_cmd_req(VirtIOSCSIReq *req)
-- 
1.7.9.5