[S390] dasd: add hyper PAV support to DASD device driver, part 1

Parallel access volumes (PAV) is a storage server feature, that allows
to start multiple channel programs on the same DASD in parallel. It
defines alias devices which can be used as alternative paths to the
same disk. With the old base PAV support we only needed rudimentary
functionality in the DASD device driver. As the mapping between base
and alias devices was static, we just had to export an identifier
(uid) and could leave the combining of devices to external layers
like a device mapper multipath.
Now hyper PAV removes the requirement to dedicate alias devices to
specific base devices. Instead each alias devices can be combined with
multiple base device on a per request basis. This requires full
support by the DASD device driver as now each channel program itself
has to identify the target base device.
The changes to the dasd device driver and the ECKD discipline are:
- Separate subchannel device representation (dasd_device) from block
  device representation (dasd_block). Only base devices are block
  devices.
- Gather information about base and alias devices and possible
  combinations.
- For each request decide which dasd_device should be used (base or
  alias) and build specific channel program.
- Support summary unit checks, which allow the storage server to
  upgrade / downgrade between base and hyper PAV at runtime (support
  is mandatory).

Signed-off-by: Stefan Weinhuber <wein@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 37 insertions, 57 deletions

diff --git a/drivers/s390/block/dasd_devmap.c b/drivers/s390/block/dasd_devmap.c
index 0c67258fb9ec..f4fb40257348 100644
--- a/drivers/s390/block/dasd_devmap.c
+++ b/drivers/s390/block/dasd_devmap.c
@@ -49,22 +49,6 @@ struct dasd_devmap {
 };
 
 /*
- * dasd_server_ssid_map contains a globally unique storage server subsystem ID.
- * dasd_server_ssid_list contains the list of all subsystem IDs accessed by
- * the DASD device driver.
- */
-struct dasd_server_ssid_map {
-        struct list_head list;
-        struct system_id {
-                char vendor[4];
-                char serial[15];
-                __u16 ssid;
-        } sid;
-};
-
-static struct list_head dasd_server_ssid_list;
-
-/*
  * Parameter parsing functions for dasd= parameter. The syntax is:
  *   <devno>            : (0x)?[0-9a-fA-F]+
  *   <busid>            : [0-0a-f]\.[0-9a-f]\.(0x)?[0-9a-fA-F]+
@@ -721,8 +705,9 @@ dasd_ro_store(struct device *dev, struct device_attribute *attr,
                 devmap->features &= ~DASD_FEATURE_READONLY;
         if (devmap->device)
                 devmap->device->features = devmap->features;
-        if (devmap->device && devmap->device->gdp)
-                set_disk_ro(devmap->device->gdp, val);
+        if (devmap->device && devmap->device->block
+            && devmap->device->block->gdp)
+                set_disk_ro(devmap->device->block->gdp, val);
         spin_unlock(&dasd_devmap_lock);
         return count;
 }
@@ -893,12 +878,16 @@ dasd_alias_show(struct device *dev, struct device_attribute *attr, char *buf)
 
         devmap = dasd_find_busid(dev->bus_id);
         spin_lock(&dasd_devmap_lock);
-        if (!IS_ERR(devmap))
-                alias = devmap->uid.alias;
+        if (IS_ERR(devmap) || strlen(devmap->uid.vendor) == 0) {
+                spin_unlock(&dasd_devmap_lock);
+                return sprintf(buf, "0\n");
+        }
+        if (devmap->uid.type == UA_BASE_PAV_ALIAS ||
+            devmap->uid.type == UA_HYPER_PAV_ALIAS)
+                alias = 1;
         else
                 alias = 0;
         spin_unlock(&dasd_devmap_lock);
-
         return sprintf(buf, alias ? "1\n" : "0\n");
 }
 
@@ -930,19 +919,36 @@ static ssize_t
 dasd_uid_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
         struct dasd_devmap *devmap;
-        char uid[UID_STRLEN];
+        char uid_string[UID_STRLEN];
+        char ua_string[3];
+        struct dasd_uid *uid;
 
         devmap = dasd_find_busid(dev->bus_id);
         spin_lock(&dasd_devmap_lock);
-        if (!IS_ERR(devmap) && strlen(devmap->uid.vendor) > 0)
-                snprintf(uid, sizeof(uid), "%s.%s.%04x.%02x",
-                         devmap->uid.vendor, devmap->uid.serial,
-                         devmap->uid.ssid, devmap->uid.unit_addr);
-        else
-                uid[0] = 0;
+        if (IS_ERR(devmap) || strlen(devmap->uid.vendor) == 0) {
+                spin_unlock(&dasd_devmap_lock);
+                return sprintf(buf, "\n");
+        }
+        uid = &devmap->uid;
+        switch (uid->type) {
+        case UA_BASE_DEVICE:
+                sprintf(ua_string, "%02x", uid->real_unit_addr);
+                break;
+        case UA_BASE_PAV_ALIAS:
+                sprintf(ua_string, "%02x", uid->base_unit_addr);
+                break;
+        case UA_HYPER_PAV_ALIAS:
+                sprintf(ua_string, "xx");
+                break;
+        default:
+                /* should not happen, treat like base device */
+                sprintf(ua_string, "%02x", uid->real_unit_addr);
+                break;
+        }
+        snprintf(uid_string, sizeof(uid_string), "%s.%s.%04x.%s",
+                 uid->vendor, uid->serial, uid->ssid, ua_string);
         spin_unlock(&dasd_devmap_lock);
-
-        return snprintf(buf, PAGE_SIZE, "%s\n", uid);
+        return snprintf(buf, PAGE_SIZE, "%s\n", uid_string);
 }
 
 static DEVICE_ATTR(uid, 0444, dasd_uid_show, NULL);
@@ -1040,39 +1046,16 @@ int
 dasd_set_uid(struct ccw_device *cdev, struct dasd_uid *uid)
 {
         struct dasd_devmap *devmap;
-        struct dasd_server_ssid_map *srv, *tmp;
 
         devmap = dasd_find_busid(cdev->dev.bus_id);
         if (IS_ERR(devmap))
                 return PTR_ERR(devmap);
 
-        /* generate entry for server_ssid_map */
-        srv = (struct dasd_server_ssid_map *)
-                kzalloc(sizeof(struct dasd_server_ssid_map), GFP_KERNEL);
-        if (!srv)
-                return -ENOMEM;
-        strncpy(srv->sid.vendor, uid->vendor, sizeof(srv->sid.vendor) - 1);
-        strncpy(srv->sid.serial, uid->serial, sizeof(srv->sid.serial) - 1);
-        srv->sid.ssid = uid->ssid;
-
-        /* server is already contained ? */
         spin_lock(&dasd_devmap_lock);
         devmap->uid = *uid;
-        list_for_each_entry(tmp, &dasd_server_ssid_list, list) {
-                if (!memcmp(&srv->sid, &tmp->sid,
-                            sizeof(struct system_id))) {
-                        kfree(srv);
-                        srv = NULL;
-                        break;
-                }
-        }
-
-        /* add servermap to serverlist */
-        if (srv)
-                list_add(&srv->list, &dasd_server_ssid_list);
         spin_unlock(&dasd_devmap_lock);
 
-        return (srv ? 1 : 0);
+        return 0;
 }
 EXPORT_SYMBOL_GPL(dasd_set_uid);
 
@@ -1138,9 +1121,6 @@ dasd_devmap_init(void)
         dasd_max_devindex = 0;
         for (i = 0; i < 256; i++)
                 INIT_LIST_HEAD(&dasd_hashlists[i]);
-
-        /* Initialize servermap structure. */
-        INIT_LIST_HEAD(&dasd_server_ssid_list);
         return 0;
 }