util: Add get feature length 2 API to support direction parameter

Since feature identifier 0Dh: host memory buffer length is affected by the
direction as mentioned by the issue #1681.

Signed-off-by: Tokunori Ikegami <[email protected]>
[dwagner: reordered definitions and declerations]
Signed-off-by: Daniel Wagner <[email protected]>

Author: ikegami-t

src/libnvme.map

@@ -5,6 +5,7 @@ LIBNVME_1_2 {
 		nvme_ctrl_get_dhchap_host_key;
 		nvme_ctrl_set_dhchap_host_key;
 		nvmf_get_discovery_wargs;
+		nvme_get_feature_length2;
 };
 
 LIBNVME_1_1 {

src/nvme/util.c

@@ -494,6 +494,22 @@ int nvme_get_feature_length(int fid, __u32 cdw11, __u32 *len)
 	return 0;
 }
 
+int nvme_get_feature_length2(int fid, __u32 cdw11, enum nvme_data_tfr dir,
+			     __u32 *len)
+{
+	switch (fid) {
+	case NVME_FEAT_FID_HOST_MEM_BUF:
+		if (dir == NVME_DATA_TFR_HOST_TO_CTRL) {
+			*len = 0;
+			break;
+		}
+		fallthrough;
+	default:
+		return nvme_get_feature_length(fid, cdw11, len);
+	}
+	return 0;
+}
+
 int nvme_get_directive_receive_length(enum nvme_directive_dtype dtype,
 		enum nvme_directive_receive_doper doper, __u32 *len)
 {

src/nvme/util.h

@@ -17,6 +17,12 @@
  * libnvme utility functions
  */
 
+#if __has_attribute(__fallthrough__)
+# define fallthrough __attribute__((__fallthrough__))
+#else
+# define fallthrough do {} while (0) /* fallthrough */
+#endif
+
 /**
  * enum nvme_connect_err - nvme connect error codes
  * @ENVME_CONNECT_RESOLVE:	failed to resolve host
@@ -155,6 +161,37 @@ void nvme_init_copy_range_f1(struct nvme_copy_range_f1 *copy, __u16 *nlbs,
  */
 int nvme_get_feature_length(int fid, __u32 cdw11, __u32 *len);
 
+/**
+ * enum nvme_data_tfr - Data transfer direction of the command
+ * @NVME_DATA_TFR_NO_DATA_TFR:		No data transfer
+ * @NVME_DATA_TFR_HOST_TO_CTRL:		Host to controller
+ * @NVME_DATA_TFR_CTRL_TO_HOST:		Controller to host
+ * @NVME_DATA_TFR_BIDIRECTIONAL:	Bidirectional
+ */
+enum nvme_data_tfr {
+	NVME_DATA_TFR_NO_DATA_TFR,
+	NVME_DATA_TFR_HOST_TO_CTRL,
+	NVME_DATA_TFR_CTRL_TO_HOST,
+	NVME_DATA_TFR_BIDIRECTIONAL
+};
+
+/**
+ * nvme_get_feature_length2() - Retreive the command payload length for a
+ *			       specific feature identifier
+ * @fid:   Feature identifier, see &enum nvme_features_id.
+ * @cdw11: The cdw11 value may affect the transfer (only known fid is
+ *	   %NVME_FEAT_FID_HOST_ID)
+ * @dir:   Data transfer direction: false - host to controller, true -
+ *	   controller to host may affect the transfer (only known fid is
+ *	   %NVME_FEAT_FID_HOST_MEM_BUF).
+ * @len:   On success, set to this features payload length in bytes.
+ *
+ * Return: 0 on success, -1 with errno set to EINVAL if the function did not
+ * recognize &fid.
+ */
+int nvme_get_feature_length2(int fid, __u32 cdw11, enum nvme_data_tfr dir,
+			     __u32 *len);
+
 /**
  * nvme_get_directive_receive_length() - Get directive receive length
  * @dtype: Directive type, see &enum nvme_directive_dtype