Kernel: Turns global Custody and Inode tables into InlineLinkedLists

Yet more of this same thing. Each one of these patches has a small but
noticeable impact on the steady-state kmalloc numbers. :^)

Kernel/FileSystem/Custody.cpp

@@ -4,18 +4,18 @@
 #include <Kernel/FileSystem/Inode.h>
 #include <Kernel/Lock.h>
 
-static Lockable<HashTable<Custody*>>& all_custodies()
+static Lockable<InlineLinkedList<Custody>>& all_custodies()
 {
-    static Lockable<HashTable<Custody*>>* table;
+    static Lockable<InlineLinkedList<Custody>>* list;
-    if (!table)
+    if (!list)
-        table = new Lockable<HashTable<Custody*>>;
+        list = new Lockable<InlineLinkedList<Custody>>;
-    return *table;
+    return *list;
 }
 
 Custody* Custody::get_if_cached(Custody* parent, const String& name)
 {
     LOCKER(all_custodies().lock());
-    for (auto& custody : all_custodies().resource()) {
+    for (auto* custody = all_custodies().resource().head(); custody; custody = custody->next()) {
         if (custody->is_deleted())
             continue;
         if (custody->is_mounted_on())
@@ -47,7 +47,7 @@ Custody::Custody(Custody* parent, const String& name, Inode& inode)
     , m_inode(inode)
 {
     LOCKER(all_custodies().lock());
-    all_custodies().resource().set(this);
+    all_custodies().resource().append(this);
 }
 
 Custody::~Custody()

Kernel/FileSystem/Custody.h

@@ -2,15 +2,17 @@
 
 #include <AK/AKString.h>
 #include <AK/Badge.h>
-#include <AK/RefPtr.h>
+#include <AK/InlineLinkedList.h>
 #include <AK/RefCounted.h>
+#include <AK/RefPtr.h>
 
 class Inode;
 class VFS;
 
 // FIXME: Custody needs some locking.
 
-class Custody : public RefCounted<Custody> {
+class Custody : public RefCounted<Custody>
+    , public InlineLinkedListNode<Custody> {
 public:
     static Custody* get_if_cached(Custody* parent, const String& name);
     static NonnullRefPtr<Custody> get_or_create(Custody* parent, const String& name, Inode&);
@@ -35,6 +37,10 @@ public:
     void did_mount_on(Badge<VFS>);
     void did_rename(Badge<VFS>, const String& name);
 
+    // For InlineLinkedListNode.
+    Custody* m_next { nullptr };
+    Custody* m_prev { nullptr };
+
 private:
     Custody(Custody* parent, const String& name, Inode&);
 

Kernel/FileSystem/Inode.cpp

@@ -5,12 +5,12 @@
 #include <Kernel/Net/LocalSocket.h>
 #include <Kernel/VM/InodeVMObject.h>
 
-HashTable<Inode*>& all_inodes()
+InlineLinkedList<Inode>& all_inodes()
 {
-    static HashTable<Inode*>* s_inode_set;
+    static InlineLinkedList<Inode>* list;
-    if (!s_inode_set)
+    if (!list)
-        s_inode_set = new HashTable<Inode*>();
+        list = new InlineLinkedList<Inode>;
-    return *s_inode_set;
+    return *list;
 }
 
 void Inode::sync()
@@ -18,7 +18,7 @@ void Inode::sync()
     NonnullRefPtrVector<Inode, 32> inodes;
     {
         InterruptDisabler disabler;
-        for (auto* inode : all_inodes()) {
+        for (auto* inode = all_inodes().head(); inode; inode = inode->next()) {
             if (inode->is_metadata_dirty())
                 inodes.append(*inode);
         }
@@ -63,7 +63,7 @@ Inode::Inode(FS& fs, unsigned index)
     : m_fs(fs)
     , m_index(index)
 {
-    all_inodes().set(this);
+    all_inodes().append(this);
 }
 
 Inode::~Inode()

Kernel/FileSystem/Inode.h

@@ -2,6 +2,7 @@
 
 #include <AK/AKString.h>
 #include <AK/Function.h>
+#include <AK/InlineLinkedList.h>
 #include <AK/RefCounted.h>
 #include <AK/WeakPtr.h>
 #include <Kernel/FileSystem/FileSystem.h>
@@ -15,7 +16,9 @@ class InodeVMObject;
 class InodeWatcher;
 class LocalSocket;
 
-class Inode : public RefCounted<Inode>, public Weakable<Inode> {
+class Inode : public RefCounted<Inode>
+    , public Weakable<Inode>
+    , public InlineLinkedListNode<Inode> {
     friend class VFS;
     friend class FS;
 
@@ -77,6 +80,10 @@ public:
     void register_watcher(Badge<InodeWatcher>, InodeWatcher&);
     void unregister_watcher(Badge<InodeWatcher>, InodeWatcher&);
 
+    // For InlineLinkedListNode.
+    Inode* m_next { nullptr };
+    Inode* m_prev { nullptr };
+
 protected:
     Inode(FS& fs, unsigned index);
     void set_metadata_dirty(bool);

Kernel/FileSystem/ProcFS.cpp

@@ -593,11 +593,11 @@ Optional<KBuffer> procfs$all(InodeIdentifier)
 
 Optional<KBuffer> procfs$inodes(InodeIdentifier)
 {
-    extern HashTable<Inode*>& all_inodes();
+    extern InlineLinkedList<Inode>& all_inodes();
     KBufferBuilder builder;
-    for (auto it : all_inodes()) {
+    InterruptDisabler disabler;
-        RefPtr<Inode> inode = *it;
+    for (auto* inode = all_inodes().head(); inode; inode = inode->next()) {
-        builder.appendf("Inode{K%x} %02u:%08u (%u)\n", inode.ptr(), inode->fsid(), inode->index(), inode->ref_count());
+        builder.appendf("Inode{K%x} %02u:%08u (%u)\n", inode, inode->fsid(), inode->index(), inode->ref_count());
     }
     return builder.build();
 }