s390/dasd: add query host access to volume support

With this feature, applications can query if a DASD volume is online
to another operating system instances by checking the online status of
all attached hosts from the storage server.

Reviewed-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Stefan Haberland <stefan.haberland@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/block/dasd.c

@@ -75,6 +75,8 @@ static void dasd_block_timeout(unsigned long);
 static void __dasd_process_erp(struct dasd_device *, struct dasd_ccw_req *);
 static void dasd_profile_init(struct dasd_profile *, struct dentry *);
 static void dasd_profile_exit(struct dasd_profile *);
+static void dasd_hosts_init(struct dentry *, struct dasd_device *);
+static void dasd_hosts_exit(struct dasd_device *);
 
 /*
  * SECTION: Operations on the device structure.
@@ -267,6 +269,7 @@ static int dasd_state_known_to_basic(struct dasd_device *device)
 		dasd_debugfs_setup(dev_name(&device->cdev->dev),
 				   dasd_debugfs_root_entry);
 	dasd_profile_init(&device->profile, device->debugfs_dentry);
+	dasd_hosts_init(device->debugfs_dentry, device);
 
 	/* register 'device' debug area, used for all DBF_DEV_XXX calls */
 	device->debug_area = debug_register(dev_name(&device->cdev->dev), 4, 1,
@@ -304,6 +307,7 @@ static int dasd_state_basic_to_known(struct dasd_device *device)
 		return rc;
 	dasd_device_clear_timer(device);
 	dasd_profile_exit(&device->profile);
+	dasd_hosts_exit(device);
 	debugfs_remove(device->debugfs_dentry);
 	DBF_DEV_EVENT(DBF_EMERG, device, "%p debug area deleted", device);
 	if (device->debug_area != NULL) {
@@ -1150,6 +1154,58 @@ int dasd_profile_on(struct dasd_profile *profile)
 
 #endif				/* CONFIG_DASD_PROFILE */
 
+static int dasd_hosts_show(struct seq_file *m, void *v)
+{
+	struct dasd_device *device;
+	int rc = -EOPNOTSUPP;
+
+	device = m->private;
+	dasd_get_device(device);
+
+	if (device->discipline->hosts_print)
+		rc = device->discipline->hosts_print(device, m);
+
+	dasd_put_device(device);
+	return rc;
+}
+
+static int dasd_hosts_open(struct inode *inode, struct file *file)
+{
+	struct dasd_device *device = inode->i_private;
+
+	return single_open(file, dasd_hosts_show, device);
+}
+
+static const struct file_operations dasd_hosts_fops = {
+	.owner		= THIS_MODULE,
+	.open		= dasd_hosts_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static void dasd_hosts_exit(struct dasd_device *device)
+{
+	debugfs_remove(device->hosts_dentry);
+	device->hosts_dentry = NULL;
+}
+
+static void dasd_hosts_init(struct dentry *base_dentry,
+			    struct dasd_device *device)
+{
+	struct dentry *pde;
+	umode_t mode;
+
+	if (!base_dentry)
+		return;
+
+	mode = S_IRUSR | S_IFREG;
+	pde = debugfs_create_file("host_access_list", mode, base_dentry,
+				  device, &dasd_hosts_fops);
+	if (pde && !IS_ERR(pde))
+		device->hosts_dentry = pde;
+}
+
 /*
  * Allocate memory for a channel program with 'cplength' channel
  * command words and 'datasize' additional space. There are two

drivers/s390/block/dasd_devmap.c

@@ -981,6 +981,32 @@ dasd_safe_offline_store(struct device *dev, struct device_attribute *attr,
 
 static DEVICE_ATTR(safe_offline, 0200, NULL, dasd_safe_offline_store);
 
+static ssize_t
+dasd_access_show(struct device *dev, struct device_attribute *attr,
+		 char *buf)
+{
+	struct ccw_device *cdev = to_ccwdev(dev);
+	struct dasd_device *device;
+	int count;
+
+	device = dasd_device_from_cdev(cdev);
+	if (IS_ERR(device))
+		return PTR_ERR(device);
+
+	if (device->discipline->host_access_count)
+		count = device->discipline->host_access_count(device);
+	else
+		count = -EOPNOTSUPP;
+
+	dasd_put_device(device);
+	if (count < 0)
+		return count;
+
+	return sprintf(buf, "%d\n", count);
+}
+
+static DEVICE_ATTR(host_access_count, 0444, dasd_access_show, NULL);
+
 static ssize_t
 dasd_discipline_show(struct device *dev, struct device_attribute *attr,
 		     char *buf)
@@ -1471,6 +1497,7 @@ static struct attribute * dasd_attrs[] = {
 	&dev_attr_reservation_policy.attr,
 	&dev_attr_last_known_reservation_state.attr,
 	&dev_attr_safe_offline.attr,
+	&dev_attr_host_access_count.attr,
 	&dev_attr_path_masks.attr,
 	NULL,
 };

drivers/s390/block/dasd_eckd.c

@@ -19,6 +19,7 @@
 #include <linux/module.h>
 #include <linux/compat.h>
 #include <linux/init.h>
+#include <linux/seq_file.h>
 
 #include <asm/css_chars.h>
 #include <asm/debug.h>
@@ -4627,6 +4628,167 @@ static int dasd_eckd_read_message_buffer(struct dasd_device *device,
 	return rc;
 }
 
+static int dasd_eckd_query_host_access(struct dasd_device *device,
+				       struct dasd_psf_query_host_access *data)
+{
+	struct dasd_eckd_private *private = device->private;
+	struct dasd_psf_query_host_access *host_access;
+	struct dasd_psf_prssd_data *prssdp;
+	struct dasd_ccw_req *cqr;
+	struct ccw1 *ccw;
+	int rc;
+
+	/* not available for HYPER PAV alias devices */
+	if (!device->block && private->lcu->pav == HYPER_PAV)
+		return -EOPNOTSUPP;
+
+	cqr = dasd_smalloc_request(DASD_ECKD_MAGIC, 1 /* PSF */	+ 1 /* RSSD */,
+				   sizeof(struct dasd_psf_prssd_data) + 1,
+				   device);
+	if (IS_ERR(cqr)) {
+		DBF_EVENT_DEVID(DBF_WARNING, device->cdev, "%s",
+				"Could not allocate read message buffer request");
+		return PTR_ERR(cqr);
+	}
+	host_access = kzalloc(sizeof(*host_access), GFP_KERNEL | GFP_DMA);
+	if (!host_access) {
+		dasd_sfree_request(cqr, device);
+		DBF_EVENT_DEVID(DBF_WARNING, device->cdev, "%s",
+				"Could not allocate host_access buffer");
+		return -ENOMEM;
+	}
+	cqr->startdev = device;
+	cqr->memdev = device;
+	cqr->block = NULL;
+	cqr->retries = 256;
+	cqr->expires = 10 * HZ;
+
+	/* Prepare for Read Subsystem Data */
+	prssdp = (struct dasd_psf_prssd_data *) cqr->data;
+	memset(prssdp, 0, sizeof(struct dasd_psf_prssd_data));
+	prssdp->order = PSF_ORDER_PRSSD;
+	prssdp->suborder = PSF_SUBORDER_QHA;	/* query host access */
+	/* LSS and Volume that will be queried */
+	prssdp->lss = private->ned->ID;
+	prssdp->volume = private->ned->unit_addr;
+	/* all other bytes of prssdp must be zero */
+
+	ccw = cqr->cpaddr;
+	ccw->cmd_code = DASD_ECKD_CCW_PSF;
+	ccw->count = sizeof(struct dasd_psf_prssd_data);
+	ccw->flags |= CCW_FLAG_CC;
+	ccw->flags |= CCW_FLAG_SLI;
+	ccw->cda = (__u32)(addr_t) prssdp;
+
+	/* Read Subsystem Data - query host access */
+	ccw++;
+	ccw->cmd_code = DASD_ECKD_CCW_RSSD;
+	ccw->count = sizeof(struct dasd_psf_query_host_access);
+	ccw->flags |= CCW_FLAG_SLI;
+	ccw->cda = (__u32)(addr_t) host_access;
+
+	cqr->buildclk = get_tod_clock();
+	cqr->status = DASD_CQR_FILLED;
+	rc = dasd_sleep_on(cqr);
+	if (rc == 0) {
+		*data = *host_access;
+	} else {
+		DBF_EVENT_DEVID(DBF_WARNING, device->cdev,
+				"Reading host access data failed with rc=%d\n",
+				rc);
+		rc = -EOPNOTSUPP;
+	}
+
+	dasd_sfree_request(cqr, cqr->memdev);
+	kfree(host_access);
+	return rc;
+}
+/*
+ * return number of grouped devices
+ */
+static int dasd_eckd_host_access_count(struct dasd_device *device)
+{
+	struct dasd_psf_query_host_access *access;
+	struct dasd_ckd_path_group_entry *entry;
+	struct dasd_ckd_host_information *info;
+	int count = 0;
+	int rc, i;
+
+	access = kzalloc(sizeof(*access), GFP_NOIO);
+	if (!access) {
+		DBF_EVENT_DEVID(DBF_WARNING, device->cdev, "%s",
+				"Could not allocate access buffer");
+		return -ENOMEM;
+	}
+	rc = dasd_eckd_query_host_access(device, access);
+	if (rc) {
+		kfree(access);
+		return rc;
+	}
+
+	info = (struct dasd_ckd_host_information *)
+		access->host_access_information;
+	for (i = 0; i < info->entry_count; i++) {
+		entry = (struct dasd_ckd_path_group_entry *)
+			(info->entry + i * info->entry_size);
+		if (entry->status_flags & DASD_ECKD_PG_GROUPED)
+			count++;
+	}
+
+	kfree(access);
+	return count;
+}
+
+/*
+ * write host access information to a sequential file
+ */
+static int dasd_hosts_print(struct dasd_device *device, struct seq_file *m)
+{
+	struct dasd_psf_query_host_access *access;
+	struct dasd_ckd_path_group_entry *entry;
+	struct dasd_ckd_host_information *info;
+	char sysplex[9] = "";
+	int rc, i, j;
+
+	access = kzalloc(sizeof(*access), GFP_NOIO);
+	if (!access) {
+		DBF_EVENT_DEVID(DBF_WARNING, device->cdev, "%s",
+				"Could not allocate access buffer");
+		return -ENOMEM;
+	}
+	rc = dasd_eckd_query_host_access(device, access);
+	if (rc) {
+		kfree(access);
+		return rc;
+	}
+
+	info = (struct dasd_ckd_host_information *)
+		access->host_access_information;
+	for (i = 0; i < info->entry_count; i++) {
+		entry = (struct dasd_ckd_path_group_entry *)
+			(info->entry + i * info->entry_size);
+		/* PGID */
+		seq_puts(m, "pgid ");
+		for (j = 0; j < 11; j++)
+			seq_printf(m, "%02x", entry->pgid[j]);
+		seq_putc(m, '\n');
+		/* FLAGS */
+		seq_printf(m, "status_flags %02x\n", entry->status_flags);
+		/* SYSPLEX NAME */
+		memcpy(&sysplex, &entry->sysplex_name, sizeof(sysplex) - 1);
+		EBCASC(sysplex, sizeof(sysplex));
+		seq_printf(m, "sysplex_name %8s\n", sysplex);
+		/* SUPPORTED CYLINDER */
+		seq_printf(m, "supported_cylinder %d\n", entry->cylinder);
+		/* TIMESTAMP */
+		seq_printf(m, "timestamp %lu\n", (unsigned long)
+			   entry->timestamp);
+	}
+	kfree(access);
+
+	return 0;
+}
+
 /*
  * Perform Subsystem Function - CUIR response
  */
@@ -5099,6 +5261,8 @@ static struct dasd_discipline dasd_eckd_discipline = {
 	.get_uid = dasd_eckd_get_uid,
 	.kick_validate = dasd_eckd_kick_validate_server,
 	.check_attention = dasd_eckd_check_attention,
+	.host_access_count = dasd_eckd_host_access_count,
+	.hosts_print = dasd_hosts_print,
 };
 
 static int __init

drivers/s390/block/dasd_eckd.h

@@ -53,6 +53,7 @@
  */
 #define PSF_ORDER_PRSSD			 0x18
 #define PSF_ORDER_CUIR_RESPONSE		 0x1A
+#define PSF_SUBORDER_QHA		 0x1C
 #define PSF_ORDER_SSC			 0x1D
 
 /*
@@ -81,6 +82,8 @@
 #define ATTENTION_LENGTH_CUIR		 0x0e
 #define ATTENTION_FORMAT_CUIR		 0x01
 
+#define DASD_ECKD_PG_GROUPED		 0x10
+
 /*
  * Size that is reportet for large volumes in the old 16-bit no_cyl field
  */
@@ -403,13 +406,41 @@ struct dasd_psf_cuir_response {
 	__u8 ssid;
 } __packed;
 
+struct dasd_ckd_path_group_entry {
+	__u8 status_flags;
+	__u8 pgid[11];
+	__u8 sysplex_name[8];
+	__u32 timestamp;
+	__u32 cylinder;
+	__u8 reserved[4];
+} __packed;
+
+struct dasd_ckd_host_information {
+	__u8 access_flags;
+	__u8 entry_size;
+	__u16 entry_count;
+	__u8 entry[16390];
+} __packed;
+
+struct dasd_psf_query_host_access {
+	__u8 access_flag;
+	__u8 version;
+	__u16 CKD_length;
+	__u16 SCSI_length;
+	__u8 unused[10];
+	__u8 host_access_information[16394];
+} __packed;
+
 /*
  * Perform Subsystem Function - Prepare for Read Subsystem Data
  */
 struct dasd_psf_prssd_data {
 	unsigned char order;
 	unsigned char flags;
-	unsigned char reserved[4];
+	unsigned char reserved1;
+	unsigned char reserved2;
+	unsigned char lss;
+	unsigned char volume;
 	unsigned char suborder;
 	unsigned char varies[5];
 } __attribute__ ((packed));

drivers/s390/block/dasd_int.h

@@ -365,6 +365,8 @@ struct dasd_discipline {
 	int (*get_uid) (struct dasd_device *, struct dasd_uid *);
 	void (*kick_validate) (struct dasd_device *);
 	int (*check_attention)(struct dasd_device *, __u8);
+	int (*host_access_count)(struct dasd_device *);
+	int (*hosts_print)(struct dasd_device *, struct seq_file *);
 };
 
 extern struct dasd_discipline *dasd_diag_discipline_pointer;
@@ -487,6 +489,7 @@ struct dasd_device {
 	unsigned long blk_timeout;
 
 	struct dentry *debugfs_dentry;
+	struct dentry *hosts_dentry;
 	struct dasd_profile profile;
 };