[PATCH] md: Avoid oops when attempting to fix read errors on raid10

We should add to the counter for the rdev *after* checking if the rdev is
NULL!!!

Signed-off-by: Neil Brown <neilb@suse.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 617012b..ddc1dfc 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1435,9 +1435,9 @@
 						sl--;
 						d = r10_bio->devs[sl].devnum;
 						rdev = conf->mirrors[d].rdev;
-						atomic_add(s, &rdev->corrected_errors);
 						if (rdev &&
 						    test_bit(In_sync, &rdev->flags)) {
+							atomic_add(s, &rdev->corrected_errors);
 							if (sync_page_io(rdev->bdev,
 									 r10_bio->devs[sl].addr +
 									 sect + rdev->data_offset,