block: Fix a buffer overrun in bio_integrity_split()

bio_integrity_split() seemed to be confusing pointers and arrays -
bip_vec in bio_integrity_payload was an array appended to the end of the
payload, so the bio_vecs in struct bio_pair should have come after the
bio_integrity_payload they're for.

Fix it by making bip_vec a pointer to the inline vecs - a later patch is
going to make more use of this pointer.

Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: Martin K. Petersen <martin.petersen@oracle.com>
diff --git a/include/linux/bio.h b/include/linux/bio.h
index b31036f..81004fd 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -182,7 +182,9 @@
 	unsigned short		bip_idx;	/* current bip_vec index */
 
 	struct work_struct	bip_work;	/* I/O completion */
-	struct bio_vec		bip_vec[0];	/* embedded bvec array */
+
+	struct bio_vec		*bip_vec;
+	struct bio_vec		bip_inline_vecs[0];/* embedded bvec array */
 };
 #endif /* CONFIG_BLK_DEV_INTEGRITY */