block: Fix bio_copy_data()

The memcpy() in bio_copy_data() was using the wrong offset vars, leading
to data corruption in weird unusual setups.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-stable <stable@vger.kernel.org> # >= v3.9
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/bio.c b/fs/bio.c
index b3b20ed..ea5035d 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -917,8 +917,8 @@
 		src_p = kmap_atomic(src_bv->bv_page);
 		dst_p = kmap_atomic(dst_bv->bv_page);
 
-		memcpy(dst_p + dst_bv->bv_offset,
-		       src_p + src_bv->bv_offset,
+		memcpy(dst_p + dst_offset,
+		       src_p + src_offset,
 		       bytes);
 
 		kunmap_atomic(dst_p);