From 306c827c876378ddc128b030b8838a8e811743f2 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Thu, 15 Aug 2024 08:27:54 +0200
Subject: [PATCH v0] pg_upgrade support for upgrading to checksums enabled

---
 src/bin/pg_upgrade/controldata.c   | 17 +++++------------
 src/bin/pg_upgrade/file.c          | 21 ++++++++++++++++++++-
 src/bin/pg_upgrade/pg_upgrade.h    |  3 ++-
 src/bin/pg_upgrade/relfilenumber.c |  2 +-
 4 files changed, 28 insertions(+), 15 deletions(-)

diff --git a/src/bin/pg_upgrade/controldata.c b/src/bin/pg_upgrade/controldata.c
index 854c6887a23..16d0b84b337 100644
--- a/src/bin/pg_upgrade/controldata.c
+++ b/src/bin/pg_upgrade/controldata.c
@@ -693,18 +693,11 @@ check_control_data(ControlData *oldctrl,
 	 * check_for_isn_and_int8_passing_mismatch().
 	 */
 
-	/*
-	 * We might eventually allow upgrades from checksum to no-checksum
-	 * clusters.
-	 */
-	if (oldctrl->data_checksum_version == 0 &&
-		newctrl->data_checksum_version != 0)
-		pg_fatal("old cluster does not use data checksums but the new one does");
-	else if (oldctrl->data_checksum_version != 0 &&
-			 newctrl->data_checksum_version == 0)
-		pg_fatal("old cluster uses data checksums but the new one does not");
-	else if (oldctrl->data_checksum_version != newctrl->data_checksum_version)
-		pg_fatal("old and new cluster pg_controldata checksum versions do not match");
+	if (user_opts.transfer_mode != TRANSFER_MODE_COPY)
+	{
+		if (oldctrl->data_checksum_version != newctrl->data_checksum_version)
+			pg_fatal("when upgrading between clusters with different data checksum settings, transfer mode --copy must be used");
+	}
 }
 
 
diff --git a/src/bin/pg_upgrade/file.c b/src/bin/pg_upgrade/file.c
index 73932504cae..cef33b8f6eb 100644
--- a/src/bin/pg_upgrade/file.c
+++ b/src/bin/pg_upgrade/file.c
@@ -80,12 +80,14 @@ cloneFile(const char *src, const char *dst,
  */
 void
 copyFile(const char *src, const char *dst,
-		 const char *schemaName, const char *relName)
+		 const char *schemaName, const char *relName,
+		 int segno)
 {
 #ifndef WIN32
 	int			src_fd;
 	int			dest_fd;
 	char	   *buffer;
+	BlockNumber blocknum;
 
 	if ((src_fd = open(src, O_RDONLY | PG_BINARY, 0)) < 0)
 		pg_fatal("error while copying relation \"%s.%s\": could not open file \"%s\": %m",
@@ -101,6 +103,8 @@ copyFile(const char *src, const char *dst,
 
 	buffer = (char *) pg_malloc(COPY_BUF_SIZE);
 
+	blocknum = segno * old_cluster.controldata.largesz;
+
 	/* perform data copying i.e read src source, write to destination */
 	while (true)
 	{
@@ -113,6 +117,19 @@ copyFile(const char *src, const char *dst,
 		if (nbytes == 0)
 			break;
 
+		if (new_cluster.controldata.data_checksum_version == 1)
+		{
+			for (int i = 0; i < 50 && i * BLCKSZ < nbytes; i++)
+			{
+				uint16		csum;
+				char	   *block = buffer + i * BLCKSZ;
+				PageHeader	header = (PageHeader) block;
+
+				csum = pg_checksum_page(block, blocknum + i);
+				header->pd_checksum = csum;
+			}
+		}
+
 		errno = 0;
 		if (write(dest_fd, buffer, nbytes) != nbytes)
 		{
@@ -122,6 +139,8 @@ copyFile(const char *src, const char *dst,
 			pg_fatal("error while copying relation \"%s.%s\": could not write file \"%s\": %m",
 					 schemaName, relName, dst);
 		}
+
+		blocknum += 50;
 	}
 
 	pg_free(buffer);
diff --git a/src/bin/pg_upgrade/pg_upgrade.h b/src/bin/pg_upgrade/pg_upgrade.h
index cdb6e2b7597..c6a4ade53a7 100644
--- a/src/bin/pg_upgrade/pg_upgrade.h
+++ b/src/bin/pg_upgrade/pg_upgrade.h
@@ -404,7 +404,8 @@ bool		pid_lock_file_exists(const char *datadir);
 void		cloneFile(const char *src, const char *dst,
 					  const char *schemaName, const char *relName);
 void		copyFile(const char *src, const char *dst,
-					 const char *schemaName, const char *relName);
+					 const char *schemaName, const char *relName,
+					 int segno);
 void		copyFileByRange(const char *src, const char *dst,
 							const char *schemaName, const char *relName);
 void		linkFile(const char *src, const char *dst,
diff --git a/src/bin/pg_upgrade/relfilenumber.c b/src/bin/pg_upgrade/relfilenumber.c
index 1d3054d78bd..2ae69d71159 100644
--- a/src/bin/pg_upgrade/relfilenumber.c
+++ b/src/bin/pg_upgrade/relfilenumber.c
@@ -250,7 +250,7 @@ transfer_relfile(FileNameMap *map, const char *type_suffix, bool vm_must_add_fro
 				case TRANSFER_MODE_COPY:
 					pg_log(PG_VERBOSE, "copying \"%s\" to \"%s\"",
 						   old_file, new_file);
-					copyFile(old_file, new_file, map->nspname, map->relname);
+					copyFile(old_file, new_file, map->nspname, map->relname, segno);
 					break;
 				case TRANSFER_MODE_COPY_FILE_RANGE:
 					pg_log(PG_VERBOSE, "copying \"%s\" to \"%s\" with copy_file_range",
-- 
2.46.0