[Issue #320] always backup and always restore pg_filenode.map

Author: gsmolk

src/data.c

@@ -711,8 +711,9 @@ backup_non_data_file(pgFile *file, pgFile *prev_file,
 	/*
 	 * If nonedata file exists in previous backup
 	 * and its mtime is less than parent backup start time ... */
-	if (prev_file && file->exists_in_prev &&
-		file->mtime <= parent_backup_time)
+	if ((pg_strcasecmp(file->name, RELMAPPER_FILENAME) != 0) &&
+		(prev_file && file->exists_in_prev &&
+		 file->mtime <= parent_backup_time))
 	{
 
 		file->crc = fio_get_crc32(from_fullpath, FIO_DB_HOST, false);

src/pg_probackup.h

@@ -70,7 +70,8 @@ extern const char  *PROGRAM_EMAIL;
 #define BACKUP_RO_LOCK_FILE		"backup_ro.pid"
 #define DATABASE_FILE_LIST		"backup_content.control"
 #define PG_BACKUP_LABEL_FILE	"backup_label"
-#define PG_TABLESPACE_MAP_FILE "tablespace_map"
+#define PG_TABLESPACE_MAP_FILE	"tablespace_map"
+#define RELMAPPER_FILENAME		"pg_filenode.map"
 #define EXTERNAL_DIR			"external_directories/externaldir"
 #define DATABASE_MAP			"database_map"
 #define HEADER_MAP  			"page_header_map"

src/restore.c

@@ -903,6 +903,11 @@ restore_chain(pgBackup *dest_backup, parray *parent_chain,
 			if (parray_bsearch(dest_backup->files, file, pgFileCompareRelPathWithExternal))
 				redundant = false;
 
+			/* pg_filenode.map are always restored, because it's crc cannot be trusted */
+			if (file->external_dir_num == 0 &&
+				pg_strcasecmp(file->name, RELMAPPER_FILENAME) == 0)
+				redundant = true;
+
 			/* do not delete the useful internal directories */
 			if (S_ISDIR(file->mode) && !redundant)
 				continue;