Kernel: Implement multi-watch InodeWatcher :^)

This patch modifies InodeWatcher to switch to a one watcher, multiple
watches architecture.  The following changes have been made:

- The watch_file syscall is removed, and in its place the
  create_iwatcher, iwatcher_add_watch and iwatcher_remove_watch calls
  have been added.
- InodeWatcher now holds multiple WatchDescriptions for each file that
  is being watched.
- The InodeWatcher file descriptor can be read from to receive events on
  all watched files.

Co-authored-by: Gunnar Beutner <gunnar@beutner.name>

1 files changed, 18 insertions, 0 deletions

diff --git a/Kernel/API/InodeWatcherFlags.h b/Kernel/API/InodeWatcherFlags.h
new file mode 100644
index 0000000000..c9cdf42b1f
--- /dev/null
+++ b/Kernel/API/InodeWatcherFlags.h
@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2021, sin-ack <sin-ack@protonmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/EnumBits.h>
+#include <AK/Types.h>
+
+enum class InodeWatcherFlags : u32 {
+    None = 0,
+    Nonblock = 1 << 0,
+    CloseOnExec = 1 << 1,
+};
+
+AK_ENUM_BITWISE_OPERATORS(InodeWatcherFlags);