raidz_test: Fix ZIO ABDs initialization

 - When filling ABDs of several segments, consider offset.
 - "Corrupt" ABDs with actually different data to fail something.

Signed-off-by: Alexander Motin <alexander.motin@TrueNAS.com>

Author: amotin

cmd/raidz_test/raidz_test.c

@@ -265,9 +265,21 @@ cmp_data(raidz_test_opts_t *opts, raidz_map_t *rm)
 
 static int
 init_rand(void *data, size_t size, void *private)
+{
+	size_t *offsetp = (size_t *)private;
+	size_t offset = *offsetp;
+
+	VERIFY3U(offset + size, <=, SPA_MAXBLOCKSIZE);
+	memcpy(data, (char *)rand_data + offset, size);
+	*offsetp = offset + size;
+	return (0);
+}
+
+static int
+corrupt_rand_fill(void *data, size_t size, void *private)
 {
 	(void) private;
-	memcpy(data, rand_data, size);
+	memset(data, 0xAA, size);
 	return (0);
 }
 
@@ -279,15 +291,16 @@ corrupt_colums(raidz_map_t *rm, const int *tgts, const int cnt)
 		for (int i = 0; i < cnt; i++) {
 			raidz_col_t *col = &rr->rr_col[tgts[i]];
 			abd_iterate_func(col->rc_abd, 0, col->rc_size,
-			    init_rand, NULL);
+			    corrupt_rand_fill, NULL);
 		}
 	}
 }
 
 void
 init_zio_abd(zio_t *zio)
 {
-	abd_iterate_func(zio->io_abd, 0, zio->io_size, init_rand, NULL);
+	size_t offset = 0;
+	abd_iterate_func(zio->io_abd, 0, zio->io_size, init_rand, &offset);
 }
 
 static void