From 24e423c71489f35cf9120339b6cc4bf74f6fb57e Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Mon, 3 Dec 2018 12:58:42 -0800
Subject: [PATCH] ircd::fs: Add support test for fallocate().

---
 include/ircd/fs/support.h |  3 +++
 ircd/fs.cc                | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/include/ircd/fs/support.h b/include/ircd/fs/support.h
index 5d21812d7..ad11f13b6 100644
--- a/include/ircd/fs/support.h
+++ b/include/ircd/fs/support.h
@@ -20,4 +20,7 @@ namespace ircd::fs::support
 
 	// Test if O_DIRECT supported at target path
 	bool direct_io(const string_view &path);
+
+	// Test if fallocate() is supported at target path
+	bool fallocate(const string_view &path, const write_opts &wopts = write_opts_default);
 }
diff --git a/ircd/fs.cc b/ircd/fs.cc
index 91a2d90b3..fdf316945 100644
--- a/ircd/fs.cc
+++ b/ircd/fs.cc
@@ -313,6 +313,40 @@ ircd::fs::path(std::string s)
 // fs/support.h
 //
 
+bool
+ircd::fs::support::fallocate(const string_view &path,
+                             const write_opts &wopts)
+try
+{
+	const fd::opts opts
+	{
+		std::ios::out
+	};
+
+	fs::fd fd
+	{
+		path, opts
+	};
+
+	fs::allocate(fd, info::page_size, wopts);
+	return true;
+}
+catch(const std::system_error &e)
+{
+	const auto &ec(e.code());
+	if(system_category(ec)) switch(ec.value())
+	{
+		case int(std::errc::invalid_argument):
+		case int(std::errc::operation_not_supported):
+			return false;
+
+		default:
+			break;
+	}
+
+	throw;
+}
+
 bool
 ircd::fs::support::direct_io(const string_view &path)
 try