MDEV-20307: Remove a useless debug check to save stack space

fil_space_encrypt(): Remove the debug check that decrypts the
just encrypted page. We are exercising the decryption of encrypted
pages enough via --suite=encryption,mariabackup. It is a waste of
computing resources to decrypt every page immediately after encrypting it.

The redundant check had been added in
commit 2bedc397 (MDEV-9931).

storage/innobase/fil/fil0crypt.cc

 /*****************************************************************************
 Copyright (C) 2013, 2015, Google Inc. All Rights Reserved.
-Copyright (c) 2014, 2019, MariaDB Corporation.
+Copyright (c) 2014, 2020, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -706,47 +706,8 @@ fil_space_encrypt(
 	fil_space_crypt_t* crypt_data = space->crypt_data;
 	ut_ad(space->n_pending_ios > 0);
 	ulint zip_size = fsp_flags_get_zip_size(space->flags);
-	byte* tmp = fil_encrypt_buf(crypt_data, space->id, offset, lsn, src_frame, zip_size, dst_frame);
-
-#ifdef UNIV_DEBUG
-	if (tmp) {
-		/* Verify that encrypted buffer is not corrupted */
-		dberr_t err = DB_SUCCESS;
-		byte* src = src_frame;
-		bool page_compressed_encrypted = (mach_read_from_2(tmp+FIL_PAGE_TYPE) == FIL_PAGE_PAGE_COMPRESSED_ENCRYPTED);
-		byte uncomp_mem[UNIV_PAGE_SIZE_MAX];
-		byte tmp_mem[UNIV_PAGE_SIZE_MAX];
-		ulint size = (zip_size) ? zip_size : UNIV_PAGE_SIZE;
-
-		if (page_compressed_encrypted) {
-			memcpy(uncomp_mem, src, srv_page_size);
-			ulint unzipped1 = fil_page_decompress(
-				tmp_mem, uncomp_mem);
-			ut_ad(unzipped1);
-			if (unzipped1 != srv_page_size) {
-				src = uncomp_mem;
-			}
-		}
-
-		ut_ad(!buf_page_is_corrupted(true, src, zip_size, space));
-		ut_ad(fil_space_decrypt(crypt_data, tmp_mem, size, tmp, &err));
-		ut_ad(err == DB_SUCCESS);
-
-		/* Need to decompress the page if it was also compressed */
-		if (page_compressed_encrypted) {
-			byte buf[UNIV_PAGE_SIZE_MAX];
-			memcpy(buf, tmp_mem, srv_page_size);
-			ulint unzipped2 = fil_page_decompress(tmp_mem, buf);
-			ut_ad(unzipped2);
-		}
-
-		memcpy(tmp_mem + FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION,
-		       src + FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION, 8);
-		ut_ad(!memcmp(src, tmp_mem, size));
-	}
-#endif /* UNIV_DEBUG */
-
-	return tmp;
+	return fil_encrypt_buf(crypt_data, space->id, offset, lsn,
+			       src_frame, zip_size, dst_frame);
 }
 
 /******************************************************************

storage/xtradb/fil/fil0crypt.cc

 /*****************************************************************************
 Copyright (C) 2013, 2015, Google Inc. All Rights Reserved.
-Copyright (c) 2014, 2019, MariaDB Corporation.
+Copyright (c) 2014, 2020, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -706,47 +706,8 @@ fil_space_encrypt(
 	fil_space_crypt_t* crypt_data = space->crypt_data;
 	ut_ad(space->n_pending_ios > 0);
 	ulint zip_size = fsp_flags_get_zip_size(space->flags);
-	byte* tmp = fil_encrypt_buf(crypt_data, space->id, offset, lsn, src_frame, zip_size, dst_frame);
-
-#ifdef UNIV_DEBUG
-	if (tmp) {
-		/* Verify that encrypted buffer is not corrupted */
-		dberr_t err = DB_SUCCESS;
-		byte* src = src_frame;
-		bool page_compressed_encrypted = (mach_read_from_2(tmp+FIL_PAGE_TYPE) == FIL_PAGE_PAGE_COMPRESSED_ENCRYPTED);
-		byte uncomp_mem[UNIV_PAGE_SIZE_MAX];
-		byte tmp_mem[UNIV_PAGE_SIZE_MAX];
-		ulint size = (zip_size) ? zip_size : UNIV_PAGE_SIZE;
-
-		if (page_compressed_encrypted) {
-			memcpy(uncomp_mem, src, srv_page_size);
-			ulint unzipped1 = fil_page_decompress(
-				tmp_mem, uncomp_mem);
-			ut_ad(unzipped1);
-			if (unzipped1 != srv_page_size) {
-				src = uncomp_mem;
-			}
-		}
-
-		ut_ad(!buf_page_is_corrupted(true, src, zip_size, space));
-		ut_ad(fil_space_decrypt(crypt_data, tmp_mem, size, tmp, &err));
-		ut_ad(err == DB_SUCCESS);
-
-		/* Need to decompress the page if it was also compressed */
-		if (page_compressed_encrypted) {
-			byte buf[UNIV_PAGE_SIZE_MAX];
-			memcpy(buf, tmp_mem, srv_page_size);
-			ulint unzipped2 = fil_page_decompress(tmp_mem, buf);
-			ut_ad(unzipped2);
-		}
-
-		memcpy(tmp_mem + FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION,
-		       src + FIL_PAGE_FILE_FLUSH_LSN_OR_KEY_VERSION, 8);
-		ut_ad(!memcmp(src, tmp_mem, size));
-	}
-#endif /* UNIV_DEBUG */
-
-	return tmp;
+	return fil_encrypt_buf(crypt_data, space->id, offset, lsn,
+			       src_frame, zip_size, dst_frame);
 }
 
 /******************************************************************