fix reading the block for ptrack backups

Author: alubennikova

src/backup.c

@@ -2668,25 +2668,30 @@ get_last_ptrack_lsn(void)
 }
 
 char *
-pg_ptrack_get_block(Oid relOid,
+pg_ptrack_get_block(Oid tblsOid,
+					Oid relOid,
 					BlockNumber blknum,
 					size_t *result_size)
 {
 	PGresult   *res;
-	char	   *params[2];
+	char	   *params[3];
 	char	   *result;
 	char	   *val;
 
 	params[0] = palloc(64);
 	params[1] = palloc(64);
+	params[2] = palloc(64);
 
 	/*
 	 * Use backup_conn, cause we can do it from any database.
 	 */
-	sprintf(params[0], "%i", relOid);
-	sprintf(params[1], "%u", blknum);
-	res = pgut_execute(backup_conn, "SELECT pg_ptrack_get_block($1, $2)",
-					2, (const char **)params, true);
+	sprintf(params[0], "%i", tblsOid);
+	sprintf(params[1], "%i", relOid);
+	sprintf(params[2], "%u", blknum);
+
+// 	elog(WARNING, "pg_ptrack_get_block(%i, %i, %u)", tblsOid, relOid, blknum);
+	res = pgut_execute(backup_conn, "SELECT pg_ptrack_get_block($1, $2, $3)",
+					3, (const char **)params, true);
 
 	if (PQnfields(res) != 1)
 		elog(WARNING, "cannot get file block for relation oid %u",
@@ -2695,16 +2700,14 @@ pg_ptrack_get_block(Oid relOid,
 	val = PQgetvalue(res, 0, 0);
 
 	if (strcmp("x", val+1) == 0)
-	{
-		/* Ptrack file is missing */
 		return NULL;
-	}
 
 	result = (char *) PQunescapeBytea((unsigned char *) PQgetvalue(res, 0, 0),
 									  result_size);
 	PQclear(res);
 	pfree(params[0]);
 	pfree(params[1]);
+	pfree(params[2]);
 
 	return result;
 }

src/data.c

@@ -227,7 +227,7 @@ backup_data_page(pgFile *file, XLogRecPtr prev_backup_start_lsn,
 {
 	BackupPageHeader	header;
 	Page 				page = malloc(BLCKSZ);
-	Page 				compressed_page = malloc(BLCKSZ);
+	Page 				compressed_page;
 	size_t				write_buffer_size;
 	char				write_buffer[BLCKSZ+sizeof(header)];
 
@@ -243,9 +243,19 @@ backup_data_page(pgFile *file, XLogRecPtr prev_backup_start_lsn,
 	{
 		while(!page_is_valid && try_again)
 		{
+			int result = read_page_from_file(file, blknum,
+											 in, out, page);
+
 			try_again--;
-			page_is_valid = read_page_from_file(file, blknum,
-												in, out, page);
+			/* This block was truncated. Do nothing */
+			if (result == 0)
+			{
+				free(page);
+				return;
+			}
+
+			if (result == 1)
+				page_is_valid = true;
 		}
 	}
 
@@ -254,13 +264,27 @@ backup_data_page(pgFile *file, XLogRecPtr prev_backup_start_lsn,
 	{
 		size_t page_size = 0;
 		free(page);
-		page = (Page) pg_ptrack_get_block(file->relOid, blknum, &page_size);
-	}
+		page = NULL;
+
+		page = (Page) pg_ptrack_get_block(file->tblspcOid, file->relOid, blknum, &page_size);
 
+		if (page == NULL)
+		{
+			elog(WARNING, "File %s, block %u, file was truncated",
+					file->path, blknum);
+			return;
+		}
+
+		if (page_size != BLCKSZ)
+			elog(ERROR, "File: %s, block %u, expected block size %lu,"
+					  "but read %d, try again",
+					   file->path, blknum, page_size, BLCKSZ);
+	}
 
 
 	file->read_size += BLCKSZ;
 
+	compressed_page = malloc(BLCKSZ);
 	header.block = blknum;
 	header.compressed_size = do_compress(compressed_page, BLCKSZ,
 										 page, BLCKSZ, compress_alg);

src/pg_probackup.h

@@ -320,7 +320,7 @@ extern const char *deparse_backup_mode(BackupMode mode);
 extern void process_block_change(ForkNumber forknum, RelFileNode rnode,
 								 BlockNumber blkno);
 
-extern char *pg_ptrack_get_block(Oid relOid, BlockNumber blknum,
+extern char *pg_ptrack_get_block(Oid tblsOid, Oid relOid, BlockNumber blknum,
 								 size_t *result_size);
 /* in restore.c */
 extern int do_restore_or_validate(time_t target_backup_id,