1 files changed, 62 insertions, 16 deletions

diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index b12c1b0d3e1d..3b48640f89d5 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -155,6 +155,7 @@ struct ubd {
 	/* name (and fd, below) of the file opened for writing, either the
 	 * backing or the cow file. */
 	char *file;
+	char *serial;
 	int count;
 	int fd;
 	__u64 size;
@@ -180,6 +181,7 @@ struct ubd {
 
 #define DEFAULT_UBD { \
 	.file = 		NULL, \
+	.serial =		NULL, \
 	.count =		0, \
 	.fd =			-1, \
 	.size =			-1, \
@@ -272,7 +274,7 @@ static int ubd_setup_common(char *str, int *index_out, char **error_out)
 {
 	struct ubd *ubd_dev;
 	struct openflags flags = global_openflags;
-	char *backing_file;
+	char *file, *backing_file, *serial;
 	int n, err = 0, i;
 
 	if(index_out) *index_out = -1;
@@ -368,24 +370,27 @@ static int ubd_setup_common(char *str, int *index_out, char **error_out)
 	goto out;
 
 break_loop:
-	backing_file = strchr(str, ',');
+	file = strsep(&str, ",:");
+	if (*file == '\0')
+		file = NULL;
 
-	if (backing_file == NULL)
-		backing_file = strchr(str, ':');
+	backing_file = strsep(&str, ",:");
+	if (*backing_file == '\0')
+		backing_file = NULL;
 
-	if(backing_file != NULL){
-		if(ubd_dev->no_cow){
-			*error_out = "Can't specify both 'd' and a cow file";
-			goto out;
-		}
-		else {
-			*backing_file = '\0';
-			backing_file++;
-		}
+	serial = strsep(&str, ",:");
+	if (*serial == '\0')
+		serial = NULL;
+
+	if (backing_file && ubd_dev->no_cow) {
+		*error_out = "Can't specify both 'd' and a cow file";
+		goto out;
 	}
+
 	err = 0;
-	ubd_dev->file = str;
+	ubd_dev->file = file;
 	ubd_dev->cow.file = backing_file;
+	ubd_dev->serial = serial;
 	ubd_dev->boot_openflags = flags;
 out:
 	mutex_unlock(&ubd_lock);
@@ -406,7 +411,7 @@ static int ubd_setup(char *str)
 
 __setup("ubd", ubd_setup);
 __uml_help(ubd_setup,
-"ubd<n><flags>=<filename>[(:|,)<filename2>]\n"
+"ubd<n><flags>=<filename>[(:|,)<filename2>][(:|,)<serial>]\n"
 "    This is used to associate a device with a file in the underlying\n"
 "    filesystem. When specifying two filenames, the first one is the\n"
 "    COW name and the second is the backing file name. As separator you can\n"
@@ -429,6 +434,12 @@ __uml_help(ubd_setup,
 "    UMLs and file locking will be turned off - this is appropriate for a\n"
 "    cluster filesystem and inappropriate at almost all other times.\n\n"
 "    't' will disable trim/discard support on the device (enabled by default).\n\n"
+"    An optional device serial number can be exposed using the serial parameter\n"
+"    on the cmdline which is exposed as a sysfs entry. This is particularly\n"
+"    useful when a unique number should be given to the device. Note when\n"
+"    specifying a label, the filename2 must be also presented. It can be\n"
+"    an empty string, in which case the backing file is not used:\n"
+"       ubd0=File,,Serial\n"
 );
 
 static int udb_setup(char *str)
@@ -868,6 +879,41 @@ static void ubd_device_release(struct device *dev)
 	*ubd_dev = ((struct ubd) DEFAULT_UBD);
 }
 
+static ssize_t serial_show(struct device *dev,
+			   struct device_attribute *attr, char *buf)
+{
+	struct gendisk *disk = dev_to_disk(dev);
+	struct ubd *ubd_dev = disk->private_data;
+
+	if (!ubd_dev)
+		return 0;
+
+	return sprintf(buf, "%s", ubd_dev->serial);
+}
+
+static DEVICE_ATTR_RO(serial);
+
+static struct attribute *ubd_attrs[] = {
+	&dev_attr_serial.attr,
+	NULL,
+};
+
+static umode_t ubd_attrs_are_visible(struct kobject *kobj,
+				     struct attribute *a, int n)
+{
+	return a->mode;
+}
+
+static const struct attribute_group ubd_attr_group = {
+	.attrs = ubd_attrs,
+	.is_visible = ubd_attrs_are_visible,
+};
+
+static const struct attribute_group *ubd_attr_groups[] = {
+	&ubd_attr_group,
+	NULL,
+};
+
 static int ubd_disk_register(int major, u64 size, int unit,
 			     struct gendisk **disk_out)
 {
@@ -899,7 +945,7 @@ static int ubd_disk_register(int major, u64 size, int unit,
 
 	disk->private_data = &ubd_devs[unit];
 	disk->queue = ubd_devs[unit].queue;
-	device_add_disk(parent, disk, NULL);
+	device_add_disk(parent, disk, ubd_attr_groups);
 
 	*disk_out = disk;
 	return 0;