NVMe: Reread partitions on metadata formats

This patch has the driver automatically reread partitions if a namespace
has a separate metadata format. Previously revalidating a disk was
sufficient to get the correct capacity set on such formatted drives,
but partitions that may exist would not have been surfaced.

Reported-by: Paul Grabinar <[e-mail]>
Signed-off-by: Keith Busch <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Tested-by: Paul Grabinar <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

drivers/block/nvme-core.c

···
 		goto out_free_disk;
 
 	add_disk(ns->disk);
-	if (ns->ms)
-		revalidate_disk(ns->disk);
+	if (ns->ms) {
+		struct block_device *bd = bdget_disk(ns->disk, 0);
+		if (!bd)
+			return;
+		if (blkdev_get(bd, FMODE_READ, NULL)) {
+			bdput(bd);
+			return;
+		}
+		blkdev_reread_part(bd);
+		blkdev_put(bd, FMODE_READ);
+	}
 	return;
  out_free_disk:
 	kfree(disk);