We don't have an nvme status to report if the driver's .queue_rq()
returns an error without dispatching the requested nvme command. Use the
return value from blk_execute_rq() for all passthrough commands so the
caller may know their command was not successful.

If the command is from the target passthrough interface and fails to
dispatch, synthesize the response back to the host as a internal target
error.

Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 drivers/nvme/host/core.c       | 16 ++++++++++++----
 drivers/nvme/host/ioctl.c      |  6 +-----
 drivers/nvme/host/nvme.h       |  2 +-
 drivers/nvme/target/passthru.c |  8 ++++----
 4 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 10bb8406e067..62af5fe7a0ce 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c

@@ -972,12 +972,12 @@ int __nvme_submit_sync_cmd(struct request_queue *q, struct nvme_command *cmd,
                        goto out;
        }

-       blk_execute_rq(NULL, req, at_head);
+       ret = blk_execute_rq(NULL, req, at_head);
        if (result)
                *result = nvme_req(req)->result;
        if (nvme_req(req)->flags & NVME_REQ_CANCELLED)
                ret = -EINTR;
-       else
+       else if (nvme_req(req)->status)