[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, 124 insertions, 1 deletions

diff --git a/drivers/s390/block/dasd_eckd.h b/drivers/s390/block/dasd_eckd.h
index 712ff1650134c..fc2509c939bc4 100644
--- a/drivers/s390/block/dasd_eckd.h
+++ b/drivers/s390/block/dasd_eckd.h
@@ -39,6 +39,8 @@
 #define DASD_ECKD_CCW_READ_CKD_MT	 0x9e
 #define DASD_ECKD_CCW_WRITE_CKD_MT	 0x9d
 #define DASD_ECKD_CCW_RESERVE		 0xB4
+#define DASD_ECKD_CCW_PFX		 0xE7
+#define DASD_ECKD_CCW_RSCK		 0xF9
 
 /*
  * Perform Subsystem Function / Sub-Orders
@@ -137,6 +139,25 @@ struct LO_eckd_data {
 	__u16 length;
 } __attribute__ ((packed));
 
+/* Prefix data for format 0x00 and 0x01 */
+struct PFX_eckd_data {
+	unsigned char format;
+	struct {
+		unsigned char define_extend:1;
+		unsigned char time_stamp:1;
+		unsigned char verify_base:1;
+		unsigned char hyper_pav:1;
+		unsigned char reserved:4;
+	} __attribute__ ((packed)) validity;
+	__u8 base_address;
+	__u8 aux;
+	__u8 base_lss;
+	__u8 reserved[7];
+	struct DE_eckd_data define_extend;
+	struct LO_eckd_data locate_record;
+	__u8 LO_extended_data[4];
+} __attribute__ ((packed));
+
 struct dasd_eckd_characteristics {
 	__u16 cu_type;
 	struct {
@@ -254,7 +275,9 @@ struct dasd_eckd_confdata {
 		} __attribute__ ((packed)) ned;
 		struct {
 			unsigned char flags;            /* byte  0    */
-			unsigned char res2[7];          /* byte  1- 7 */
+			unsigned char res1;		/* byte  1    */
+			__u16 format;			/* byte  2-3  */
+			unsigned char res2[4];		/* byte  4-7  */
 			unsigned char sua_flags;	/* byte  8    */
 			__u8 base_unit_addr;            /* byte  9    */
 			unsigned char res3[22];	        /* byte 10-31 */
@@ -343,6 +366,11 @@ struct dasd_eckd_path {
 	__u8 npm;
 };
 
+struct dasd_rssd_features {
+	char feature[256];
+} __attribute__((packed));
+
+
 /*
  * Perform Subsystem Function - Prepare for Read Subsystem Data
  */
@@ -365,4 +393,99 @@ struct dasd_psf_ssc_data {
 	unsigned char reserved[59];
 } __attribute__((packed));
 
+
+/*
+ * some structures and definitions for alias handling
+ */
+struct dasd_unit_address_configuration {
+	struct {
+		char ua_type;
+		char base_ua;
+	} unit[256];
+} __attribute__((packed));
+
+
+#define MAX_DEVICES_PER_LCU 256
+
+/* flags on the LCU  */
+#define NEED_UAC_UPDATE  0x01
+#define UPDATE_PENDING	0x02
+
+enum pavtype {NO_PAV, BASE_PAV, HYPER_PAV};
+
+
+struct alias_root {
+	struct list_head serverlist;
+	spinlock_t lock;
+};
+
+struct alias_server {
+	struct list_head server;
+	struct dasd_uid uid;
+	struct list_head lculist;
+};
+
+struct summary_unit_check_work_data {
+	char reason;
+	struct dasd_device *device;
+	struct work_struct worker;
+};
+
+struct read_uac_work_data {
+	struct dasd_device *device;
+	struct delayed_work dwork;
+};
+
+struct alias_lcu {
+	struct list_head lcu;
+	struct dasd_uid uid;
+	enum pavtype pav;
+	char flags;
+	spinlock_t lock;
+	struct list_head grouplist;
+	struct list_head active_devices;
+	struct list_head inactive_devices;
+	struct dasd_unit_address_configuration *uac;
+	struct summary_unit_check_work_data suc_data;
+	struct read_uac_work_data ruac_data;
+	struct dasd_ccw_req *rsu_cqr;
+};
+
+struct alias_pav_group {
+	struct list_head group;
+	struct dasd_uid uid;
+	struct alias_lcu *lcu;
+	struct list_head baselist;
+	struct list_head aliaslist;
+	struct dasd_device *next;
+};
+
+
+struct dasd_eckd_private {
+	struct dasd_eckd_characteristics rdc_data;
+	struct dasd_eckd_confdata conf_data;
+	struct dasd_eckd_path path_data;
+	struct eckd_count count_area[5];
+	int init_cqr_status;
+	int uses_cdl;
+	struct attrib_data_t attrib;	/* e.g. cache operations */
+	struct dasd_rssd_features features;
+
+	/* alias managemnet */
+	struct dasd_uid uid;
+	struct alias_pav_group *pavgroup;
+	struct alias_lcu *lcu;
+	int count;
+};
+
+
+
+int dasd_alias_make_device_known_to_lcu(struct dasd_device *);
+void dasd_alias_disconnect_device_from_lcu(struct dasd_device *);
+int dasd_alias_add_device(struct dasd_device *);
+int dasd_alias_remove_device(struct dasd_device *);
+struct dasd_device *dasd_alias_get_start_dev(struct dasd_device *);
+void dasd_alias_handle_summary_unit_check(struct dasd_device *, struct irb *);
+void dasd_eckd_reset_ccw_to_base_io(struct dasd_ccw_req *);
+
 #endif				/* DASD_ECKD_H */