From e22cd98a4f8ee82bc84276a61f9ddb95ca2aa098 Mon Sep 17 00:00:00 2001
From: Emery Hemingway <emery@vfemail.net>
Date: Thu, 17 Mar 2016 16:29:27 +0100
Subject: [PATCH] File_system::Connection: session upgrading

Upgrade the File_system session RAM quota when an Out_of_metadata
exception is caught.

Issue #1751
Issue #1909
---
 .../include/file_system_session/connection.h  | 75 +++++++++++++++++--
 1 file changed, 68 insertions(+), 7 deletions(-)

diff --git a/repos/os/include/file_system_session/connection.h b/repos/os/include/file_system_session/connection.h
index f6802cdc33..691e350658 100644
--- a/repos/os/include/file_system_session/connection.h
+++ b/repos/os/include/file_system_session/connection.h
@@ -5,7 +5,7 @@
  */
 
 /*
- * Copyright (C) 2012-2013 Genode Labs GmbH
+ * Copyright (C) 2012-2016 Genode Labs GmbH
  *
  * This file is part of the Genode OS framework, which is distributed
  * under the terms of the GNU General Public License version 2.
@@ -17,9 +17,11 @@
 #include <file_system_session/client.h>
 #include <base/connection.h>
 #include <base/allocator.h>
+#include <util/retry.h>
 
 namespace File_system {
 
+	struct Connection_base;
 	struct Connection;
 
 	/* recommended packet transmission buffer size */
@@ -28,7 +30,10 @@ namespace File_system {
 }
 
 
-struct File_system::Connection : Genode::Connection<Session>, Session_client
+/**
+ * The base implementation of a File_system connection
+ */
+struct File_system::Connection_base : Genode::Connection<Session>, Session_client
 {
 	/**
 	 * Constructor
@@ -36,12 +41,15 @@ struct File_system::Connection : Genode::Connection<Session>, Session_client
 	 * \param tx_buffer_alloc  allocator used for managing the
 	 *                         transmission buffer
 	 * \param tx_buf_size      size of transmission buffer in bytes
+	 * \param label            session label
+	 * \param root             root directory of session
+	 * \param writeable        session is writable
 	 */
-	Connection(Genode::Range_allocator &tx_block_alloc,
-	           size_t                   tx_buf_size = DEFAULT_TX_BUF_SIZE,
-	           char const              *label       = "",
-	           char const              *root        = "/",
-	           bool                     writeable   = true)
+	Connection_base(Genode::Range_allocator &tx_block_alloc,
+	                size_t                   tx_buf_size = DEFAULT_TX_BUF_SIZE,
+	                char const              *label       = "",
+	                char const              *root        = "/",
+	                bool                     writeable   = true)
 	:
 		Genode::Connection<Session>(
 			session("ram_quota=%zd, "
@@ -56,4 +64,57 @@ struct File_system::Connection : Genode::Connection<Session>, Session_client
 	{ }
 };
 
+
+/**
+ * A File_system connection that upgrades its RAM quota
+ */
+struct File_system::Connection : File_system::Connection_base
+{
+	/* reuse constructor */
+	using Connection_base::Connection_base;
+
+	/**
+	 * Upgrade the session quota in response to Out_of_metadata
+	 */
+	void upgrade_ram()
+	{
+		PWRN("upgrading File_system session");
+		Genode::env()->parent()->upgrade(cap(), "ram=8K");
+	}
+
+	enum { UPGRADE_ATTEMPTS = 2 };
+
+	Dir_handle dir(Path const &path, bool create) override
+	{
+		return Genode::retry<Out_of_metadata>(
+			[&] () { return Session_client::dir(path, create); },
+			[&] () { upgrade_ram(); },
+			UPGRADE_ATTEMPTS);
+	}
+
+	File_handle file(Dir_handle dir, Name const &name, Mode mode, bool create) override
+	{
+		return Genode::retry<Out_of_metadata>(
+			[&] () { return Session_client::file(dir, name, mode, create); },
+			[&] () { upgrade_ram(); },
+			UPGRADE_ATTEMPTS);
+	}
+
+	Symlink_handle symlink(Dir_handle dir, Name const &name, bool create) override
+	{
+		return Genode::retry<Out_of_metadata>(
+			[&] () { return Session_client::symlink(dir, name, create); },
+			[&] () { upgrade_ram(); },
+			UPGRADE_ATTEMPTS);
+	}
+
+	Node_handle node(Path const &path) override
+	{
+		return Genode::retry<Out_of_metadata>(
+			[&] () { return Session_client::node(path); },
+			[&] () { upgrade_ram(); },
+			UPGRADE_ATTEMPTS);
+	}
+};
+
 #endif /* _INCLUDE__FILE_SYSTEM_SESSION__CONNECTION_H_ */