block: pass correct prot_buf pointer to integrity metadata processing function

The prot_buf pointer passed to the generate/verify functions is incorrect for the second and subsequent range, making it impossible to verify the guard tag. The patch correctly increments the prot_buf pointer by the tuple size for each pass.

---

index 5cbd5d9..c7cbf60 100644
@@ -226,13 +226,13 @@ static int bio_integrity_process(struct bio *bio,
 	iter.disk_name = bio->bi_bdev->bd_disk->disk_name;
 	iter.interval = bi->interval;
 	iter.seed = bip_get_seed(bip);
-	iter.prot_buf = prot_buf;
 
 	bio_for_each_segment(bv, bio, bviter) {
 		void *kaddr = kmap_atomic(bv.bv_page);
 
 		iter.data_buf = kaddr + bv.bv_offset;
 		iter.data_size = bv.bv_len;
+		iter.prot_buf = prot_buf;
 
 		ret = proc_fn(&iter);
 		if (ret) {

@@ -241,6 +241,7 @@ static int bio_integrity_process(struct bio *bio,
 		}
 
 		kunmap_atomic(kaddr);
+		prot_buf += bi->tuple_size;
 	}
 	return ret;
 }

Hey Sam,

Sam> The prot_buf pointer passed to the generate/verify functions is Sam> incorrect for the second and subsequent range, making it impossible Sam> to verify the guard tag. The patch correctly increments the Sam> prot_buf pointer by the tuple size for each pass.

prot_buf is just a temporary variable used to get the kernel address of the buffer pointer. We only care about iter.prot_buf and that gets incremented by the generate or verify functions.

Are your data buffers page aligned? Things are going to break if they aren't...

Martin K. Petersen	Oracle Linux Engineering