1 files changed, 88 insertions, 0 deletions
diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index 2ac365e97cc..a280a1e7be3 100644
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -2206,6 +2206,94 @@ FileSync(File file, uint32 wait_event_info)
 	return returnCode;
 }
 
+/*
+ * Zero a region of the file.
+ *
+ * Returns 0 on success, -1 otherwise. In the latter case errno is set to the
+ * appropriate error.
+ */
+int
+FileZero(File file, off_t offset, off_t amount, uint32 wait_event_info)
+{
+	int			returnCode;
+	ssize_t		written;
+
+	Assert(FileIsValid(file));
+
+	DO_DB(elog(LOG, "FileZero: %d (%s) " INT64_FORMAT " " INT64_FORMAT,
+			   file, VfdCache[file].fileName,
+			   (int64) offset, (int64) amount));
+
+	returnCode = FileAccess(file);
+	if (returnCode < 0)
+		return returnCode;
+
+	pgstat_report_wait_start(wait_event_info);
+	written = pg_pwrite_zeros(VfdCache[file].fd, amount, offset);
+	pgstat_report_wait_end();
+
+	if (written < 0)
+		return -1;
+	else if (written != amount)
+	{
+		/* if errno is unset, assume problem is no disk space */
+		if (errno == 0)
+			errno = ENOSPC;
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * Try to reserve file space with posix_fallocate(). If posix_fallocate() is
+ * not implemented on the operating system or fails with EINVAL / EOPNOTSUPP,
+ * use FileZero() instead.
+ *
+ * Note that at least glibc() implements posix_fallocate() in userspace if not
+ * implemented by the filesystem. That's not the case for all environments
+ * though.
+ *
+ * Returns 0 on success, -1 otherwise. In the latter case errno is set to the
+ * appropriate error.
+ */
+int
+FileFallocate(File file, off_t offset, off_t amount, uint32 wait_event_info)
+{
+#ifdef HAVE_POSIX_FALLOCATE
+	int			returnCode;
+
+	Assert(FileIsValid(file));
+
+	DO_DB(elog(LOG, "FileFallocate: %d (%s) " INT64_FORMAT " " INT64_FORMAT,
+			   file, VfdCache[file].fileName,
+			   (int64) offset, (int64) amount));
+
+	returnCode = FileAccess(file);
+	if (returnCode < 0)
+		return -1;
+
+	pgstat_report_wait_start(wait_event_info);
+	returnCode = posix_fallocate(VfdCache[file].fd, offset, amount);
+	pgstat_report_wait_end();
+
+	if (returnCode == 0)
+		return 0;
+
+	/* for compatibility with %m printing etc */
+	errno = returnCode;
+
+	/*
+	 * Return in cases of a "real" failure, if fallocate is not supported,
+	 * fall through to the FileZero() backed implementation.
+	 */
+	if (returnCode != EINVAL && returnCode != EOPNOTSUPP)
+		return -1;
+#endif
+
+	return FileZero(file, offset, amount, wait_event_info);
+}
+
 off_t
 FileSize(File file)
 {