nvme/cuse: Poll the io_msg queue when the admin queue is polled

Users already have to poll the admin queue, so embed the io_msg
queue polling there to simplify the API.

Signed-off-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/472833 (master)

(cherry picked from commit 11739f3cb1)
Change-Id: I4d4d3be100be0798bee4096e0bbda96e20d2405e
Signed-off-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/472963
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>

doc/nvme.md

@@ -283,11 +283,12 @@ locations:
 ~~~
 
 Requests from CUSE are handled by pthreads when controller and namespaces are created.
-Those pass the I/O or admin commands via a ring to a thread that processes them using
-spdk_nvme_io_msg_process().
+During the handling of CUSE requests, operations may be forwarded to an internal NVMe
+queue pair. The user must poll this internal queue pair periodically by polling
+the admin qpair for the associated NVMe controller.
 
 Ioctls that request information attained when attaching NVMe controller receive an
-immediate response, without passing them through the ring.
+immediate response, without passing them to the internal queue pair.
 
 This interface reserves one qpair for sending down the I/O for each controller.
 

include/spdk/nvme.h

@@ -1246,26 +1246,6 @@ int spdk_nvme_ctrlr_cmd_io_raw_with_md(struct spdk_nvme_ctrlr *ctrlr,
 int32_t spdk_nvme_qpair_process_completions(struct spdk_nvme_qpair *qpair,
 		uint32_t max_completions);
 
-/**
- * Process IO message sent to controller from external module.
- *
- * This call process requests from the ring, send IO to an allocated qpair or
- * admin commands in its context. This call is non-blocking and intended to be
- * polled by SPDK thread to provide safe environment for NVMe request
- * completition sent by external module to controller.
- *
- * The caller must ensure that each controller is polled by only one thread at
- * a time.
- *
- * This function may be called at any point while the controller is attached to
- * the SPDK NVMe driver.
- *
- * \param ctrlr Opaque handle to NVMe controller.
- *
- * \return number of processed external IO messages.
- */
-int spdk_nvme_io_msg_process(struct spdk_nvme_ctrlr *ctrlr);
-
 /**
  * Send the given admin command to the NVMe controller.
  *

lib/nvme/nvme_ctrlr.c

@@ -34,6 +34,7 @@
 #include "spdk/stdinc.h"
 
 #include "nvme_internal.h"
+#include "nvme_io_msg.h"
 
 #include "spdk/env.h"
 #include "spdk/string.h"
@@ -2646,14 +2647,30 @@ int32_t
 spdk_nvme_ctrlr_process_admin_completions(struct spdk_nvme_ctrlr *ctrlr)
 {
 	int32_t num_completions;
+	int32_t rc;
 
 	nvme_robust_mutex_lock(&ctrlr->ctrlr_lock);
+
 	if (ctrlr->keep_alive_interval_ticks) {
 		nvme_ctrlr_keep_alive(ctrlr);
 	}
-	num_completions = spdk_nvme_qpair_process_completions(ctrlr->adminq, 0);
+
+	rc = spdk_nvme_io_msg_process(ctrlr);
+	if (rc < 0) {
+		nvme_robust_mutex_unlock(&ctrlr->ctrlr_lock);
+		return rc;
+	}
+	num_completions = rc;
+
+	rc = spdk_nvme_qpair_process_completions(ctrlr->adminq, 0);
 	nvme_robust_mutex_unlock(&ctrlr->ctrlr_lock);
 
+	if (rc < 0) {
+		num_completions = rc;
+	} else {
+		num_completions += rc;
+	}
+
 	return num_completions;
 }
 

lib/nvme/nvme_io_msg.h

@@ -58,6 +58,26 @@ struct nvme_io_msg_producer {
 int nvme_io_msg_send(struct spdk_nvme_ctrlr *ctrlr, uint32_t nsid, spdk_nvme_io_msg_fn fn,
 		     void *arg);
 
+/**
+ * Process IO message sent to controller from external module.
+ *
+ * This call process requests from the ring, send IO to an allocated qpair or
+ * admin commands in its context. This call is non-blocking and intended to be
+ * polled by SPDK thread to provide safe environment for NVMe request
+ * completition sent by external module to controller.
+ *
+ * The caller must ensure that each controller is polled by only one thread at
+ * a time.
+ *
+ * This function may be called at any point while the controller is attached to
+ * the SPDK NVMe driver.
+ *
+ * \param ctrlr Opaque handle to NVMe controller.
+ *
+ * \return number of processed external IO messages.
+ */
+int spdk_nvme_io_msg_process(struct spdk_nvme_ctrlr *ctrlr);
+
 int nvme_io_msg_ctrlr_start(struct spdk_nvme_ctrlr *ctrlr,
 			    struct nvme_io_msg_producer *io_msg_producer);
 void nvme_io_msg_ctrlr_stop(struct spdk_nvme_ctrlr *ctrlr,

module/bdev/nvme/bdev_nvme.c

@@ -210,13 +210,6 @@ bdev_nvme_poll_adminq(void *arg)
 {
 	struct spdk_nvme_ctrlr *ctrlr = arg;
 
-	/* Process io messages that were passed from non-polled mode threads
-	 * to this ctrlr. This is used as part of nvme cuse support for surfacing
-	 * /dev nodes that can be used by standard Linux management applications
-	 * like nvme-cli.
-	 */
-	spdk_nvme_io_msg_process(ctrlr);
-
 	return spdk_nvme_ctrlr_process_admin_completions(ctrlr);
 }