[S390] dasd: Add support for raw ECKD access.

Normal I/O operations through the DASD device driver give only access
to the data fields of an ECKD device even for track based I/O.
This patch extends the DASD device driver to give access to whole
ECKD tracks including count, key and data fields.

Signed-off-by: Stefan Haberland <stefan.haberland@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/dasd.h

@@ -73,6 +73,7 @@ typedef struct dasd_information2_t {
  * 0x02: use diag discipline (diag)
  * 0x04: set the device initially online (internal use only)
  * 0x08: enable ERP related logging
+ * 0x20: give access to raw eckd data
  */
 #define DASD_FEATURE_DEFAULT	     0x00
 #define DASD_FEATURE_READONLY	     0x01
@@ -81,6 +82,7 @@ typedef struct dasd_information2_t {
 #define DASD_FEATURE_ERPLOG	     0x08
 #define DASD_FEATURE_FAILFAST	     0x10
 #define DASD_FEATURE_FAILONSLCK      0x20
+#define DASD_FEATURE_USERAW	     0x40
 
 #define DASD_PARTN_BITS 2
 

drivers/s390/block/dasd.c

@@ -369,6 +369,11 @@ dasd_state_ready_to_online(struct dasd_device * device)
 	device->state = DASD_STATE_ONLINE;
 	if (device->block) {
 		dasd_schedule_block_bh(device->block);
+		if ((device->features & DASD_FEATURE_USERAW)) {
+			disk = device->block->gdp;
+			kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
+			return 0;
+		}
 		disk = device->block->bdev->bd_disk;
 		disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
 		while ((part = disk_part_iter_next(&piter)))
@@ -394,7 +399,7 @@ static int dasd_state_online_to_ready(struct dasd_device *device)
 			return rc;
 	}
 	device->state = DASD_STATE_READY;
-	if (device->block) {
+	if (device->block && !(device->features & DASD_FEATURE_USERAW)) {
 		disk = device->block->bdev->bd_disk;
 		disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
 		while ((part = disk_part_iter_next(&piter)))
@@ -2258,8 +2263,20 @@ static void dasd_setup_queue(struct dasd_block *block)
 {
 	int max;
 
-	blk_queue_logical_block_size(block->request_queue, block->bp_block);
-	max = block->base->discipline->max_blocks << block->s2b_shift;
+	if (block->base->features & DASD_FEATURE_USERAW) {
+		/*
+		 * the max_blocks value for raw_track access is 256
+		 * it is higher than the native ECKD value because we
+		 * only need one ccw per track
+		 * so the max_hw_sectors are
+		 * 2048 x 512B = 1024kB = 16 tracks
+		 */
+		max = 2048;
+	} else {
+		max = block->base->discipline->max_blocks << block->s2b_shift;
+	}
+	blk_queue_logical_block_size(block->request_queue,
+				     block->bp_block);
 	blk_queue_max_hw_sectors(block->request_queue, max);
 	blk_queue_max_segments(block->request_queue, -1L);
 	/* with page sized segments we can translate each segement into

drivers/s390/block/dasd_devmap.c

@@ -208,6 +208,8 @@ dasd_feature_list(char *str, char **endp)
 			features |= DASD_FEATURE_READONLY;
 		else if (len == 4 && !strncmp(str, "diag", 4))
 			features |= DASD_FEATURE_USEDIAG;
+		else if (len == 3 && !strncmp(str, "raw", 3))
+			features |= DASD_FEATURE_USERAW;
 		else if (len == 6 && !strncmp(str, "erplog", 6))
 			features |= DASD_FEATURE_ERPLOG;
 		else if (len == 8 && !strncmp(str, "failfast", 8))
@@ -857,7 +859,7 @@ dasd_use_diag_store(struct device *dev, struct device_attribute *attr,
 	spin_lock(&dasd_devmap_lock);
 	/* Changing diag discipline flag is only allowed in offline state. */
 	rc = count;
-	if (!devmap->device) {
+	if (!devmap->device && !(devmap->features & DASD_FEATURE_USERAW)) {
 		if (val)
 			devmap->features |= DASD_FEATURE_USEDIAG;
 		else
@@ -870,6 +872,56 @@ dasd_use_diag_store(struct device *dev, struct device_attribute *attr,
 
 static DEVICE_ATTR(use_diag, 0644, dasd_use_diag_show, dasd_use_diag_store);
 
+/*
+ * use_raw controls whether the driver should give access to raw eckd data or
+ * operate in standard mode
+ */
+static ssize_t
+dasd_use_raw_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct dasd_devmap *devmap;
+	int use_raw;
+
+	devmap = dasd_find_busid(dev_name(dev));
+	if (!IS_ERR(devmap))
+		use_raw = (devmap->features & DASD_FEATURE_USERAW) != 0;
+	else
+		use_raw = (DASD_FEATURE_DEFAULT & DASD_FEATURE_USERAW) != 0;
+	return sprintf(buf, use_raw ? "1\n" : "0\n");
+}
+
+static ssize_t
+dasd_use_raw_store(struct device *dev, struct device_attribute *attr,
+		    const char *buf, size_t count)
+{
+	struct dasd_devmap *devmap;
+	ssize_t rc;
+	unsigned long val;
+
+	devmap = dasd_devmap_from_cdev(to_ccwdev(dev));
+	if (IS_ERR(devmap))
+		return PTR_ERR(devmap);
+
+	if ((strict_strtoul(buf, 10, &val) != 0) || val > 1)
+		return -EINVAL;
+
+	spin_lock(&dasd_devmap_lock);
+	/* Changing diag discipline flag is only allowed in offline state. */
+	rc = count;
+	if (!devmap->device && !(devmap->features & DASD_FEATURE_USEDIAG)) {
+		if (val)
+			devmap->features |= DASD_FEATURE_USERAW;
+		else
+			devmap->features &= ~DASD_FEATURE_USERAW;
+	} else
+		rc = -EPERM;
+	spin_unlock(&dasd_devmap_lock);
+	return rc;
+}
+
+static DEVICE_ATTR(raw_track_access, 0644, dasd_use_raw_show,
+		   dasd_use_raw_store);
+
 static ssize_t
 dasd_discipline_show(struct device *dev, struct device_attribute *attr,
 		     char *buf)
@@ -1232,6 +1284,7 @@ static struct attribute * dasd_attrs[] = {
 	&dev_attr_vendor.attr,
 	&dev_attr_uid.attr,
 	&dev_attr_use_diag.attr,
+	&dev_attr_raw_track_access.attr,
 	&dev_attr_eer_enabled.attr,
 	&dev_attr_erplog.attr,
 	&dev_attr_failfast.attr,