Revert "md: improve partition detection in md array"

This reverts commit 5b479c91da90eef605f851508744bfe8269591a0.

Quoth Neil Brown:

  "It causes an oops when auto-detecting raid arrays, and it doesn't
   seem easy to fix.

   The array may not be 'open' when do_md_run is called, so
   bdev->bd_disk might be NULL, so bd_set_size can oops.

   This whole approach of opening an md device before it has been
   assembled just seems to get more and more painful.  I think I'm going
   to have to come up with something clever to provide both backward
   comparability with usage expectation, and sane integration into the
   rest of the kernel."

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 1b7130c..97ee870 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -2063,6 +2063,7 @@
 	 */
 	mddev->array_size = sectors>>1;
 	set_capacity(mddev->gendisk, mddev->array_size << 1);
+	mddev->changed = 1;
 	if (mddev->array_size > mddev->size && mddev->recovery_cp == MaxSector) {
 		mddev->recovery_cp = mddev->size << 1;
 		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);