block: move header for /proc/partitions to seq_start

The seq_start call is the better place for the header for the file, that
way we don't have to be mucking in the class structure to try to figure
out if this is the first partition or not.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

block/genhd.c

@@ -305,6 +305,10 @@ static int find_start(struct device *dev, void *data)
 static void *part_start(struct seq_file *part, loff_t *pos)
 {
 	struct device *dev;
+	loff_t n = *pos;
+
+	if (!n)
+		seq_puts(part, "major minor  #blocks  name\n\n");
 
 	mutex_lock(&block_class_lock);
 	dev = class_find_device(&block_class, NULL, (void *)pos, find_start);
@@ -338,9 +342,6 @@ static int show_partition(struct seq_file *part, void *v)
 	int n;
 	char buf[BDEVNAME_SIZE];
 
-	if (&sgp->dev.node == block_class.devices.next)
-		seq_puts(part, "major minor  #blocks  name\n\n");
-
 	/* Don't show non-partitionable removeable devices or empty devices */
 	if (!get_capacity(sgp) ||
 			(sgp->minors == 1 && (sgp->flags & GENHD_FL_REMOVABLE)))