refactor(pio): Add distinct variables for offset and length

Author: Artyom Ivanov

src/jrd/os/posix/unix.cpp

@@ -320,13 +320,16 @@ void PIO_extend(thread_db* tdbb, jrd_file* file, const ULONG extPages, const USH
 	if (file->fil_flags & FIL_no_fast_extend)
 		return;
 
-	const off_t filePages = PIO_get_number_of_pages(file, pageSize);
-	const off_t extendBy = MIN(MAX_ULONG - filePages, extPages);
+	const ULONG filePages = PIO_get_number_of_pages(file, pageSize);
+	const ULONG extendBy = MIN(MAX_ULONG - filePages, extPages);
+
+	const off_t offset = static_cast<off_t>(filePages) * pageSize;
+	const off_t length = static_cast<off_t>(extendBy) * pageSize;
 
 	int r;
 	for (r = 0; r < IO_RETRY; r++)
 	{
-		int err = fallocate(file->fil_desc, 0, filePages * pageSize, extendBy * pageSize);
+		int err = fallocate(file->fil_desc, 0, offset, length);
 		if (err == 0)
 			break;