block: Poison bip buffer with 0x88 to expose missing DMAs

---

diff --git a/fs/bio-integrity.c b/fs/bio-integrity.c
--- a/fs/bio-integrity.c
+++ b/fs/bio-integrity.c
@@ -343,6 +343,7 @@ int bio_integrity_prep(struct bio *bio)
 		return -EIO;
 	}
 
+	memset(buf, 0x88, len);
 	end = (((unsigned long) buf) + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 	start = ((unsigned long) buf) >> PAGE_SHIFT;
 	nr_pages = end - start;