lib/nvme: Add spdk_nvme_ns_get_ctrlr to the public api

This can be used in callbacks when a user has a namespace but needs to
call controller specific functions such as alloc_io_qpair.

Change-Id: I00c931e2846e42f540c17f3254fe97a45e9bd079
Signed-off-by: Seth Howell <seth.howell@intel.com>
Reviewed-on: https://review.gerrithub.io/375022
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>

CHANGELOG.md

@@ -29,6 +29,9 @@ into account when splitting I/O requests.
 The HotplugEnable option in `[Nvme]` sections of the configuration file is now
 "No" by default. It was previously "Yes".
 
+The NVMe library now includes a function spdk_nvme_ns_get_ctrlr which returns the
+NVMe Controller associated with a given namespace.
+
 ### NVMe-oF Target (nvmf)
 
 The NVMe-oF target no longer requires any in capsule data buffers to run, and
@@ -42,6 +45,7 @@ additional clarity when constructing spdk_mempools. Previously, -1 could be
 passed and the library would choose a reasonable default, but this new value
 makes it explicit that the default is being used.
 
+
 ## v17.07: Build system improvements, userspace vhost-blk target, and GPT bdev
 
 ### Build System

include/spdk/nvme.h

@@ -847,6 +847,14 @@ const struct spdk_nvme_ns_data *spdk_nvme_ns_get_data(struct spdk_nvme_ns *ns);
  */
 uint32_t spdk_nvme_ns_get_id(struct spdk_nvme_ns *ns);
 
+/**
+ * \brief Get the Controller with which this namespace is associated.
+ *
+ * This function is thread safe and can be called at any point while the controller is attached to
+ *  the SPDK NVMe driver.
+ */
+struct spdk_nvme_ctrlr *spdk_nvme_ns_get_ctrlr(struct spdk_nvme_ns *ns);
+
 /**
  * \brief Determine whether a namespace is active.
  *

lib/nvme/nvme_ns.c

@@ -143,6 +143,12 @@ spdk_nvme_ns_is_active(struct spdk_nvme_ns *ns)
 	return nsdata->ncap != 0;
 }
 
+struct spdk_nvme_ctrlr *
+spdk_nvme_ns_get_ctrlr(struct spdk_nvme_ns *ns)
+{
+	return ns->ctrlr;
+}
+
 uint32_t
 spdk_nvme_ns_get_max_io_xfer_size(struct spdk_nvme_ns *ns)
 {