scst: Add "dummy" LUN support (merge r4874 and r4875 from the trunk)

git-svn-id: http://svn.code.sf.net/p/scst/svn/branches/2.2.x@4883 d57e44dd-8a1f-0410-8b47-8ef2f437770f

scst/README

@@ -902,6 +902,15 @@ Intended to be used for performance measurements at the same way as
 blocksize, read_only, removable. See vdisk_fileio above for description
 of those parameters.
 
+vdisk_nullio also has extra attribute:
+
+ - dummy - if this flag is set, LUNs corresponding to this device will
+   not appear at the initiator side. This is because SCST will set the
+   PERIPHERAL QUALIFIER qualifier field to 1 (not connected) and the
+   PERIPHERAL DEVICE TYPE to 0x1f (no device) in the INQUIRY response.
+   See also SPC-4 for more information. It is designed to be used as a
+   "dummy" placeholder on LUN 0, if LUN 0 is not desired.
+
 Handler vcdrom allows emulation of a virtual CDROM device using an ISO
 file as backend. It doesn't have any parameters.
 
@@ -992,7 +1001,7 @@ description of those parameters.
 Each vdisk_nullio's device has the following attributes in
 /sys/kernel/scst_tgt/devices/device_name: blocksize, read_only,
 removable, size_mb, t10_dev_id, threads_num, threads_pool_type, type,
-usn. See above description of those parameters.
+usn, dummy. See above description of those parameters.
 
 Each vcdrom's device has the following attributes in
 /sys/kernel/scst_tgt/devices/device_name: filename, size_mb,

scst/README_in-tree

@@ -766,6 +766,15 @@ Intended to be used for performance measurements at the same way as
 blocksize, read_only, removable. See vdisk_fileio above for description
 of those parameters.
 
+vdisk_nullio also has extra attribute:
+
+ - dummy - if this flag is set, LUNs corresponding to this device will
+   not appear at the initiator side. This is because SCST will set the
+   PERIPHERAL QUALIFIER qualifier field to 1 (not connected) and the
+   PERIPHERAL DEVICE TYPE to 0x1f (no device) in the INQUIRY response.
+   See also SPC-4 for more information. It is designed to be used as a
+   "dummy" placeholder on LUN 0, if LUN 0 is not desired.
+
 Handler vcdrom allows emulation of a virtual CDROM device using an ISO
 file as backend. It doesn't have any parameters.
 
@@ -850,7 +859,7 @@ description of those parameters.
 Each vdisk_nullio's device has the following attributes in
 /sys/kernel/scst_tgt/devices/device_name: blocksize, read_only,
 removable, size_mb, t10_dev_id, threads_num, threads_pool_type, type,
-usn. See above description of those parameters.
+usn, dummy. See above description of those parameters.
 
 Each vcdrom's device has the following attributes in
 /sys/kernel/scst_tgt/devices/device_name: filename, size_mb,

scst/src/dev_handlers/scst_vdisk.c

@@ -105,6 +105,7 @@ static struct scst_trace_log vdisk_local_trace_tbl[] = {
 #define DEF_WRITE_THROUGH		0
 #define DEF_NV_CACHE			0
 #define DEF_O_DIRECT			0
+#define DEF_DUMMY			0
 #define DEF_REMOVABLE			0
 #define DEF_THIN_PROVISIONED		0
 
@@ -153,6 +154,7 @@ struct scst_vdisk_dev {
 	unsigned int nullio:1;
 	unsigned int blockio:1;
 	unsigned int cdrom_empty:1;
+	unsigned int dummy:1;
 	unsigned int removable:1;
 	unsigned int thin_provisioned:1;
 
@@ -264,6 +266,8 @@ static ssize_t vdisk_sysfs_nv_cache_show(struct kobject *kobj,
 	struct kobj_attribute *attr, char *buf);
 static ssize_t vdisk_sysfs_o_direct_show(struct kobject *kobj,
 	struct kobj_attribute *attr, char *buf);
+static ssize_t vdev_sysfs_dummy_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf);
 static ssize_t vdisk_sysfs_removable_show(struct kobject *kobj,
 	struct kobj_attribute *attr, char *buf);
 static ssize_t vdev_sysfs_filename_show(struct kobject *kobj,
@@ -296,6 +300,8 @@ static struct kobj_attribute vdisk_nv_cache_attr =
 	__ATTR(nv_cache, S_IRUGO, vdisk_sysfs_nv_cache_show, NULL);
 static struct kobj_attribute vdisk_o_direct_attr =
 	__ATTR(o_direct, S_IRUGO, vdisk_sysfs_o_direct_show, NULL);
+static struct kobj_attribute vdev_dummy_attr =
+	__ATTR(dummy, S_IRUGO, vdev_sysfs_dummy_show, NULL);
 static struct kobj_attribute vdisk_removable_attr =
 	__ATTR(removable, S_IRUGO, vdisk_sysfs_removable_show, NULL);
 static struct kobj_attribute vdisk_filename_attr =
@@ -346,6 +352,7 @@ static const struct attribute *vdisk_nullio_attrs[] = {
 	&vdev_size_attr.attr,
 	&vdisk_blocksize_attr.attr,
 	&vdisk_rd_only_attr.attr,
+	&vdev_dummy_attr.attr,
 	&vdisk_removable_attr.attr,
 	&vdev_t10_dev_id_attr.attr,
 	&vdev_usn_attr.attr,
@@ -467,7 +474,7 @@ static struct scst_dev_type vdisk_null_devtype = {
 	.add_device =		vdisk_add_nullio_device,
 	.del_device =		vdisk_del_device,
 	.dev_attrs =		vdisk_nullio_attrs,
-	.add_device_parameters = "blocksize, read_only, removable",
+	.add_device_parameters = "blocksize, read_only, dummy, removable",
 #endif
 #if defined(CONFIG_SCST_DEBUG) || defined(CONFIG_SCST_TRACING)
 	.default_trace_flags =	SCST_DEFAULT_DEV_LOG_FLAGS,
@@ -1457,7 +1464,8 @@ static void vdisk_exec_inquiry(struct scst_cmd *cmd)
 		goto out_put;
 	}
 
-	buf[0] = cmd->dev->type;      /* type dev */
+	buf[0] = virt_dev->dummy ? SCSI_INQ_PQ_NOT_CON << 5 | 0x1f :
+		 SCSI_INQ_PQ_CON << 5 | cmd->dev->type;
 	/* Vital Product */
 	if (cmd->cdb[1] & EVPD) {
 		if (0 == cmd->cdb[2]) {
@@ -3336,6 +3344,10 @@ static void vdisk_report_registering(const struct scst_vdisk_dev *virt_dev)
 		i += snprintf(&buf[i], sizeof(buf) - i, "%sTHIN PROVISIONED",
 			(j == i) ? "(" : ", ");
 
+	if (virt_dev->dummy)
+		i += snprintf(&buf[i], sizeof(buf) - i, "%sDUMMY",
+			(j == i) ? "(" : ", ");
+
 	if (j == i)
 		PRINT_INFO("%s", buf);
 	else
@@ -3411,6 +3423,7 @@ static int vdev_create(struct scst_dev_type *devt,
 	virt_dev->vdev_devt = devt;
 
 	virt_dev->rd_only = DEF_RD_ONLY;
+	virt_dev->dummy = DEF_DUMMY;
 	virt_dev->removable = DEF_REMOVABLE;
 	virt_dev->thin_provisioned = DEF_THIN_PROVISIONED;
 
@@ -3455,7 +3468,7 @@ static void vdev_destroy(struct scst_vdisk_dev *virt_dev)
 #ifndef CONFIG_SCST_PROC
 
 static int vdev_parse_add_dev_params(struct scst_vdisk_dev *virt_dev,
-	char *params, const char *allowed_params[])
+	char *params, const char *const allowed_params[])
 {
 	int res = 0;
 	unsigned long val;
@@ -3477,7 +3490,7 @@ static int vdev_parse_add_dev_params(struct scst_vdisk_dev *virt_dev,
 		}
 
 		if (allowed_params != NULL) {
-			const char **a = allowed_params;
+			const char *const *a = allowed_params;
 			bool allowed = false;
 
 			while (*a != NULL) {
@@ -3554,6 +3567,13 @@ static int vdev_parse_add_dev_params(struct scst_vdisk_dev *virt_dev,
 		} else if (!strcasecmp("read_only", p)) {
 			virt_dev->rd_only = val;
 			TRACE_DBG("READ ONLY %d", virt_dev->rd_only);
+		} else if (!strcasecmp("dummy", p)) {
+			if (val > 1) {
+				res = -EINVAL;
+				goto out;
+			}
+			virt_dev->dummy = val;
+			TRACE_DBG("DUMMY %d", virt_dev->dummy);
 		} else if (!strcasecmp("removable", p)) {
 			virt_dev->removable = val;
 			TRACE_DBG("REMOVABLE %d", virt_dev->removable);
@@ -3650,8 +3670,8 @@ out_destroy:
 static int vdev_blockio_add_device(const char *device_name, char *params)
 {
 	int res = 0;
-	const char *allowed_params[] = { "filename", "read_only", "removable",
-					 "blocksize", "nv_cache",
+	const char *const allowed_params[] = { "filename", "read_only",
+					 "removable", "blocksize", "nv_cache",
 					 "thin_provisioned", NULL };
 	struct scst_vdisk_dev *virt_dev;
 
@@ -3705,8 +3725,9 @@ out_destroy:
 static int vdev_nullio_add_device(const char *device_name, char *params)
 {
 	int res = 0;
-	const char *allowed_params[] = { "read_only", "removable",
-					 "blocksize", NULL };
+	static const char *const allowed_params[] = {
+		"read_only", "dummy", "removable", "blocksize", NULL
+	};
 	struct scst_vdisk_dev *virt_dev;
 
 	TRACE_ENTRY();
@@ -4289,6 +4310,17 @@ static ssize_t vdisk_sysfs_o_direct_show(struct kobject *kobj,
 	return pos;
 }
 
+static ssize_t vdev_sysfs_dummy_show(struct kobject *kobj,
+				     struct kobj_attribute *attr, char *buf)
+{
+	struct scst_device *dev = container_of(kobj, struct scst_device,
+					       dev_kobj);
+	struct scst_vdisk_dev *virt_dev = dev->dh_priv;
+
+	return sprintf(buf, "%d\n%s", virt_dev->dummy,
+		 virt_dev->dummy != DEF_DUMMY ? SCST_SYSFS_KEY_MARK "\n" : "");
+}
+
 static ssize_t vdisk_sysfs_removable_show(struct kobject *kobj,
 	struct kobj_attribute *attr, char *buf)
 {

scstadmin/scstadmin.sysfs/man5/scst.conf.5

@@ -149,6 +149,16 @@ HANDLER vdisk_blockio {
 .br
 }
 .IP
+HANDLER vdisk_nullio {
+.br
+	DEVICE dummy {
+.br
+		dummy 1
+.br
+	}
+.br
+}
+.IP
 HANDLER vcdrom {
 .br
 	DEVICE cdrom1 {
@@ -208,6 +218,9 @@ TARGET_DRIVER qla2x00t {
 	TARGET 25:00:00:f0:98:87:92:f3 {
 .br
 		enabled 1
+.br
+		LUN 0 dummy
+.br
 .IP
 		GROUP INI1 {
 .br