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, 5 insertions, 2 deletions

diff --git a/Kernel/FileSystem/Inode.h b/Kernel/FileSystem/Inode.h
index 6eb78be34d..3b027402e6 100644
--- a/Kernel/FileSystem/Inode.h
+++ b/Kernel/FileSystem/Inode.h
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, sin-ack <sin-ack@protonmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -111,8 +112,10 @@ protected:
     void set_metadata_dirty(bool);
     KResult prepare_to_write_data();
 
-    void did_add_child(const InodeIdentifier&);
-    void did_remove_child(const InodeIdentifier&);
+    void did_add_child(InodeIdentifier const& child_id, String const& name);
+    void did_remove_child(InodeIdentifier const& child_id, String const& name);
+    void did_modify_contents();
+    void did_delete_self();
 
     mutable Lock m_lock { "Inode" };