brd: add ram disk visibility option

Currenly ram disk is not visiable inside /proc/partitions. This was
done for compatibility reasons here: 53978d0a. But some utilities
expect disk presents in /proc/partitions.
Let's add module's option and let's administrator chose visibility behaviour.
By default, old behaviour preserved.
Signed-off-by: NDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: NJens Axboe <axboe@fb.com>

drivers/block/brd.c

@@ -442,12 +442,15 @@ static int rd_nr;
 int rd_size = CONFIG_BLK_DEV_RAM_SIZE;
 static int max_part;
 static int part_shift;
+static int part_show = 0;
 module_param(rd_nr, int, S_IRUGO);
 MODULE_PARM_DESC(rd_nr, "Maximum number of brd devices");
 module_param(rd_size, int, S_IRUGO);
 MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes.");
 module_param(max_part, int, S_IRUGO);
 MODULE_PARM_DESC(max_part, "Maximum number of partitions per RAM disk");
+module_param(part_show, int, S_IRUGO);
+MODULE_PARM_DESC(part_show, "Control RAM disk visibility in /proc/partitions");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR);
 MODULE_ALIAS("rd");
@@ -501,7 +504,8 @@ static struct brd_device *brd_alloc(int i)
 	disk->fops		= &brd_fops;
 	disk->private_data	= brd;
 	disk->queue		= brd->brd_queue;
-	disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
+	if (!part_show)
+		disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
 	sprintf(disk->disk_name, "ram%d", i);
 	set_capacity(disk, rd_size * 2);