bdev: Add spdk_bdev_get_acwu function

This function is required for NVMf implementation
for compare and write fused command.

Signed-off-by: Maciej Szwed <maciej.szwed@intel.com>
Change-Id: If41611f5c0b8e4ed8eec66f09858c724f1800d59

Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/477914
Community-CI: Broadcom SPDK FC-NVMe CI <spdk-ci.pdl@broadcom.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Paul Luse <paul.e.luse@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>

CHANGELOG.md

@@ -135,6 +135,8 @@ The functions `spdk_reactor_enable_framework_monitor_context_switch()` and
 Added spdk_bdev_io_get_nvme_fused_status function for translating bdev_io status to NVMe status
 code for fused compare-and-write operation.
 
+Added spdk_bdev_get_acwu function for getting block device atomic compare and write unit size.
+
 ## v19.10:
 
 ### rpc

include/spdk/bdev.h

@@ -505,6 +505,14 @@ bool spdk_bdev_has_write_cache(const struct spdk_bdev *bdev);
  */
 const struct spdk_uuid *spdk_bdev_get_uuid(const struct spdk_bdev *bdev);
 
+/**
+ * Get block device atomic compare and write unit.
+ *
+ * \param bdev Block device to query.
+ * \return Atomic compare and write unit for this bdev in blocks.
+ */
+uint16_t spdk_bdev_get_acwu(const struct spdk_bdev *bdev);
+
 /**
  * Get block device metadata size.
  *

lib/bdev/bdev.c

@@ -2855,6 +2855,12 @@ spdk_bdev_get_uuid(const struct spdk_bdev *bdev)
 	return &bdev->uuid;
 }
 
+uint16_t
+spdk_bdev_get_acwu(const struct spdk_bdev *bdev)
+{
+	return bdev->acwu;
+}
+
 uint32_t
 spdk_bdev_get_md_size(const struct spdk_bdev *bdev)
 {