Re: [dm-devel] [PATCH 04/25] nvme: split nvme status from block req->errors

[Johannes Thumshirn]

On Thu, Apr 06, 2017 at 05:39:23PM +0200, Christoph Hellwig wrote:
> We want our own clearly defined error field for NVMe passthrough commands,
> and the request errors field is going away in its current form.
> 
> Just store the status and result field in the nvme_request field from
> hardirq completion context (using a new helper) and then generate a
> Linux errno for the block layer only when we actually need it.
> 
> Because we can't overload the status value with a negative error code
> for cancelled command we now have a flags filed in struct nvme_request
> that contains a bit for this condition.
> 
> Signed-off-by: Christoph Hellwig 
> ---

Looks good,
Reviewed-by: Johannes Thumshirn 

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[dm-devel] [PATCH 04/25] nvme: split nvme status from block req->errors

[Christoph Hellwig]

We want our own clearly defined error field for NVMe passthrough commands,
and the request errors field is going away in its current form.

Just store the status and result field in the nvme_request field from
hardirq completion context (using a new helper) and then generate a
Linux errno for the block layer only when we actually need it.

Because we can't overload the status value with a negative error code
for cancelled command we now have a flags filed in struct nvme_request
that contains a bit for this condition.

Signed-off-by: Christoph Hellwig 
---
 drivers/nvme/host/core.c | 50 +++-
 drivers/nvme/host/fc.c   | 10 -
 drivers/nvme/host/lightnvm.c |  9 +---
 drivers/nvme/host/nvme.h | 33 +
 drivers/nvme/host/pci.c  | 11 +-
 drivers/nvme/host/rdma.c |  5 ++---
 drivers/nvme/target/loop.c   |  7 ++-
 7 files changed, 65 insertions(+), 60 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index dc05f41c3992..b73a86a78379 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -66,11 +66,24 @@ static DEFINE_SPINLOCK(dev_list_lock);
 
 static struct class *nvme_class;
 
+int nvme_error_status(struct request *req)
+{
+   switch (nvme_req(req)->status & 0x7ff) {
+   case NVME_SC_SUCCESS:
+   return 0;
+   case NVME_SC_CAP_EXCEEDED:
+   return -ENOSPC;
+   default:
+   return -EIO;
+   }
+}
+EXPORT_SYMBOL_GPL(nvme_error_status);
+
 static inline bool nvme_req_needs_retry(struct request *req)
 {
if (blk_noretry_request(req))
return false;
-   if (req->errors & NVME_SC_DNR)
+   if (nvme_req(req)->status & NVME_SC_DNR)
return false;
if (jiffies - req->start_time >= req->timeout)
return false;
@@ -81,23 +94,13 @@ static inline bool nvme_req_needs_retry(struct request *req)
 
 void nvme_complete_rq(struct request *req)
 {
-   int error = 0;
-
-   if (unlikely(req->errors)) {
-   if (nvme_req_needs_retry(req)) {
-   nvme_req(req)->retries++;
-   blk_mq_requeue_request(req,
-   !blk_mq_queue_stopped(req->q));
-   return;
-   }
-
-   if (blk_rq_is_passthrough(req))
-   error = req->errors;
-   else
-   error = nvme_error_status(req->errors);
+   if (unlikely(nvme_req(req)->status && nvme_req_needs_retry(req))) {
+   nvme_req(req)->retries++;
+   blk_mq_requeue_request(req, !blk_mq_queue_stopped(req->q));
+   return;
}
 
-   blk_mq_end_request(req, error);
+   blk_mq_end_request(req, nvme_error_status(req));
 }
 EXPORT_SYMBOL_GPL(nvme_complete_rq);
 
@@ -114,7 +117,9 @@ void nvme_cancel_request(struct request *req, void *data, 
bool reserved)
status = NVME_SC_ABORT_REQ;
if (blk_queue_dying(req->q))
status |= NVME_SC_DNR;
-   blk_mq_complete_request(req, status);
+   nvme_req(req)->status = status;
+   blk_mq_complete_request(req, 0);
+
 }
 EXPORT_SYMBOL_GPL(nvme_cancel_request);
 
@@ -357,6 +362,7 @@ int nvme_setup_cmd(struct nvme_ns *ns, struct request *req,
 
if (!(req->rq_flags & RQF_DONTPREP)) {
nvme_req(req)->retries = 0;
+   nvme_req(req)->flags = 0;
req->rq_flags |= RQF_DONTPREP;
}
 
@@ -411,7 +417,10 @@ int __nvme_submit_sync_cmd(struct request_queue *q, struct 
nvme_command *cmd,
blk_execute_rq(req->q, NULL, req, at_head);
if (result)
*result = nvme_req(req)->result;
-   ret = req->errors;
+   if (nvme_req(req)->flags & NVME_REQ_CANCELLED)
+   ret = -EINTR;
+   else
+   ret = nvme_req(req)->status;
  out:
blk_mq_free_request(req);
return ret;
@@ -496,7 +505,10 @@ int __nvme_submit_user_cmd(struct request_queue *q, struct 
nvme_command *cmd,
}
  submit:
blk_execute_rq(req->q, disk, req, 0);
-   ret = req->errors;
+   if (nvme_req(req)->flags & NVME_REQ_CANCELLED)
+   ret = -EINTR;
+   else
+   ret = nvme_req(req)->status;
if (result)
*result = le32_to_cpu(nvme_req(req)->result.u32);
if (meta && !ret && !write) {
diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index aad7f9c0be32..450733c8cd24 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -1148,6 +1148,7 @@ nvme_fc_fcpio_done(struct nvmefc_fcp_req *req)
struct nvme_fc_queue *queue = op->queue;
struct nvme_completion *cqe = >rsp_iu.cqe;
__le16 status = cpu_to_le16(NVME_SC_SUCCESS << 1);
+   union nvme_result result;
 
/*
 * WARNING:
@@ -1215,7 +1216,7 @@ nvme_fc_fcpio_done(struct