tunedasd: add copy_pair swap capability

Add an option to tunedasd to trigger a copy pair swap using the appropriate
ioctl for DASD devices.

      -s, --copy-pair-swap COPY_PAIR

This command requires a comma separated pair of primary,secondary to be
specified. In case of success the old secondary will become the new primary
device and the old primary will become a secondary device.

Example:

tunedasd /dev/dasda -s 0.0.9700,0.0.9740

This will set the old secondary device 0.0.9740 as the new primary.
The old primary device 0.0.9700 will automatically become a secondary
device.

Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

libdasd/dasd_ioctl.c

@@ -452,3 +452,31 @@ int dasd_reset_profile(const char *device)
 
 	return 0;
 }
+
+/*
+ * Initiate the swap of a copy pairs primary,secondary relation.
+ * The old secondary will become the new primary and vice versa.
+ *
+ * @param[in] device node	device node's name
+ * @param[in] copy_pair data	pointer to dasd copypair data with:
+ *				'primary' old primary, becoming secondary
+ *				'secondary' old secondary, becoming primary.
+ *
+ * @retval errno	in case of failure
+ * @retval 0		in case of success
+ * @retval 1		swap data invalid
+ * @retval 2		no active device found
+ * @retval 3		wrong primary specified
+ * @retval 4		secondary device not found
+ * @retval 5		swap already running
+ */
+int dasd_copy_swap(const char *device, struct dasd_copypair_swap_data *data)
+{
+	int fd;
+
+	fd = dasd_open_device(device, O_RDONLY);
+	RUN_IOCTL(fd, BIODASDPPRCSWAP, data);
+	dasd_close_device(fd);
+
+	return 0;
+}