Move VFS sources into Kernel/.

2025-07-27 13:57:35 +00:00 · 2019-01-23 05:13:17 +01:00 · 2019-01-23 05:13:17 +01:00 · 754037874c
commit 754037874c
parent 19104570cc
49 changed files with 35 additions and 37 deletions
--- a/Kernel/CharacterDevice.cpp
+++ b/Kernel/CharacterDevice.cpp
@ -0,0 +1,16 @@
+#include "CharacterDevice.h"
+#include <LibC/errno_numbers.h>
+
+CharacterDevice::~CharacterDevice()
+{
+}
+
+RetainPtr<FileDescriptor> CharacterDevice::open(int& error, int options)
+{
+    return VFS::the().open(*this, error, options);
+}
+
+int CharacterDevice::ioctl(Process&, unsigned, unsigned)
+{
+    return -ENOTTY;
+}
--- a/Kernel/CharacterDevice.h
+++ b/Kernel/CharacterDevice.h
@ -0,0 +1,40 @@
+#pragma once
+
+#include <AK/Retainable.h>
+#include <AK/Types.h>
+#include "Limits.h"
+#include "FileDescriptor.h"
+
+class Process;
+
+class CharacterDevice : public Retainable<CharacterDevice> {
+public:
+    virtual ~CharacterDevice();
+
+    InodeMetadata metadata() const { return { }; }
+
+    virtual RetainPtr<FileDescriptor> open(int& error, int options);
+
+    virtual bool can_read(Process&) const = 0;
+    virtual bool can_write(Process&) const = 0;
+
+    virtual ssize_t read(Process&, byte* buffer, size_t bufferSize) = 0;
+    virtual ssize_t write(Process&, const byte* buffer, size_t bufferSize) = 0;
+
+    unsigned major() const { return m_major; }
+    unsigned minor() const { return m_minor; }
+
+    virtual bool is_tty() const { return false; }
+    virtual bool is_master_pty() const { return false; }
+
+    virtual int ioctl(Process&, unsigned request, unsigned arg);
+
+    virtual const char* class_name() const = 0;
+
+protected:
+    CharacterDevice(unsigned major, unsigned minor) : m_major(major), m_minor(minor) { }
+
+private:
+    unsigned m_major { 0 };
+    unsigned m_minor { 0 };
+};
--- a/Kernel/Console.h
+++ b/Kernel/Console.h
@ -2,7 +2,7 @@

 #include <AK/Compiler.h>
 #include <AK/Vector.h>
-#include <VirtualFileSystem/CharacterDevice.h>
+#include <Kernel/CharacterDevice.h>

 class ConsoleImplementation {
 public:
--- a/Kernel/DiskBackedFileSystem.cpp
+++ b/Kernel/DiskBackedFileSystem.cpp
@ -0,0 +1,75 @@
+#include "DiskBackedFileSystem.h"
+#include "i386.h"
+
+//#define DBFS_DEBUG
+
+DiskBackedFS::DiskBackedFS(RetainPtr<DiskDevice>&& device)
+    : m_device(move(device))
+{
+    ASSERT(m_device);
+}
+
+DiskBackedFS::~DiskBackedFS()
+{
+}
+
+bool DiskBackedFS::writeBlock(unsigned index, const ByteBuffer& data)
+{
+#ifdef DBFS_DEBUG
+    kprintf("DiskBackedFileSystem::writeBlock %u, size=%u\n", index, data.size());
+#endif
+    ASSERT(data.size() == blockSize());
+    DiskOffset baseOffset = static_cast<DiskOffset>(index) * static_cast<DiskOffset>(blockSize());
+    return device().write(baseOffset, blockSize(), data.pointer());
+}
+
+bool DiskBackedFS::writeBlocks(unsigned index, unsigned count, const ByteBuffer& data)
+{
+#ifdef DBFS_DEBUG
+    kprintf("DiskBackedFileSystem::writeBlocks %u x%u\n", index, count);
+#endif
+    DiskOffset baseOffset = static_cast<DiskOffset>(index) * static_cast<DiskOffset>(blockSize());
+    return device().write(baseOffset, count * blockSize(), data.pointer());
+}
+
+ByteBuffer DiskBackedFS::readBlock(unsigned index) const
+{
+#ifdef DBFS_DEBUG
+    kprintf("DiskBackedFileSystem::readBlock %u\n", index);
+#endif
+    auto buffer = ByteBuffer::create_uninitialized(blockSize());
+    //kprintf("created block buffer with size %u\n", blockSize());
+    DiskOffset baseOffset = static_cast<DiskOffset>(index) * static_cast<DiskOffset>(blockSize());
+    auto* bufferPointer = buffer.pointer();
+    bool success = device().read(baseOffset, blockSize(), bufferPointer);
+    ASSERT(success);
+    ASSERT(buffer.size() == blockSize());
+    return buffer;
+}
+
+ByteBuffer DiskBackedFS::readBlocks(unsigned index, unsigned count) const
+{
+    if (!count)
+        return nullptr;
+    if (count == 1)
+        return readBlock(index);
+    auto blocks = ByteBuffer::create_uninitialized(count * blockSize());
+    byte* out = blocks.pointer();
+
+    for (unsigned i = 0; i < count; ++i) {
+        auto block = readBlock(index + i);
+        if (!block)
+            return nullptr;
+        memcpy(out, block.pointer(), block.size());
+        out += blockSize();
+    }
+
+    return blocks;
+}
+
+void DiskBackedFS::setBlockSize(unsigned blockSize)
+{
+    if (blockSize == m_blockSize)
+        return;
+    m_blockSize = blockSize;
+}
--- a/Kernel/DiskBackedFileSystem.h
+++ b/Kernel/DiskBackedFileSystem.h
@ -0,0 +1,29 @@
+#pragma once
+
+#include "FileSystem.h"
+#include <AK/ByteBuffer.h>
+
+class DiskBackedFS : public FS {
+public:
+    virtual ~DiskBackedFS() override;
+
+    DiskDevice& device() { return *m_device; }
+    const DiskDevice& device() const { return *m_device; }
+
+    size_t blockSize() const { return m_blockSize; }
+
+protected:
+    explicit DiskBackedFS(RetainPtr<DiskDevice>&&);
+
+    void setBlockSize(unsigned);
+
+    ByteBuffer readBlock(unsigned index) const;
+    ByteBuffer readBlocks(unsigned index, unsigned count) const;
+
+    bool writeBlock(unsigned index, const ByteBuffer&);
+    bool writeBlocks(unsigned index, unsigned count, const ByteBuffer&);
+
+private:
+    size_t m_blockSize { 0 };
+    RetainPtr<DiskDevice> m_device;
+};
--- a/Kernel/DiskDevice.cpp
+++ b/Kernel/DiskDevice.cpp
@ -0,0 +1,43 @@
+#include "DiskDevice.h"
+
+DiskDevice::DiskDevice()
+{
+}
+
+DiskDevice::~DiskDevice()
+{
+}
+
+bool DiskDevice::read(DiskOffset offset, unsigned length, byte* out) const
+{
+    //kprintf("DD::read %u x%u\n", offset, length);
+    ASSERT((offset % block_size()) == 0);
+    ASSERT((length % block_size()) == 0);
+    dword firstBlock = offset / block_size();
+    dword endBlock = (offset + length) / block_size();
+    byte* outptr = out;
+    for (unsigned bi = firstBlock; bi < endBlock; ++bi) {
+        if (!read_block(bi, outptr))
+            return false;
+        outptr += block_size();
+    }
+    return true;
+}
+
+bool DiskDevice::write(DiskOffset offset, unsigned length, const byte* in)
+{
+    ASSERT((offset % block_size()) == 0);
+    ASSERT((length % block_size()) == 0);
+    dword firstBlock = offset / block_size();
+    dword endBlock = (offset + length) / block_size();
+    ASSERT(firstBlock <= 0xffffffff);
+    ASSERT(endBlock <= 0xffffffff);
+    const byte* inptr = in;
+    for (unsigned bi = firstBlock; bi < endBlock; ++bi) {
+        if (!write_block(bi, inptr))
+            return false;
+        inptr += block_size();
+    }
+    return true;
+}
+
--- a/Kernel/DiskDevice.h
+++ b/Kernel/DiskDevice.h
@ -0,0 +1,23 @@
+#pragma once
+
+#include <AK/Retainable.h>
+#include <AK/Types.h>
+
+// FIXME: Support 64-bit DiskOffset
+typedef dword DiskOffset;
+
+class DiskDevice : public Retainable<DiskDevice> {
+public:
+    virtual ~DiskDevice();
+
+    virtual unsigned block_size() const = 0;
+    virtual bool read_block(unsigned index, byte*) const = 0;
+    virtual bool write_block(unsigned index, const byte*) = 0;
+    virtual const char* class_name() const = 0;
+    bool read(DiskOffset, unsigned length, byte*) const;
+    bool write(DiskOffset, unsigned length, const byte*);
+
+protected:
+    DiskDevice();
+};
+
--- a/Kernel/Ext2FileSystem.cpp
+++ b/Kernel/Ext2FileSystem.cpp
--- a/Kernel/Ext2FileSystem.h
+++ b/Kernel/Ext2FileSystem.h
@ -0,0 +1,140 @@
+#pragma once
+
+#include "DiskBackedFileSystem.h"
+#include "UnixTypes.h"
+#include <AK/Buffer.h>
+#include <AK/OwnPtr.h>
+#include <AK/Lock.h>
+#include "ext2_fs.h"
+
+struct ext2_group_desc;
+struct ext2_inode;
+struct ext2_super_block;
+
+class Ext2FS;
+
+class Ext2FSInode final : public Inode {
+    friend class Ext2FS;
+public:
+    virtual ~Ext2FSInode() override;
+
+    size_t size() const { return m_raw_inode.i_size; }
+    bool is_symlink() const { return isSymbolicLink(m_raw_inode.i_mode); }
+
+    // ^Inode (Retainable magic)
+    virtual void one_retain_left() override;
+
+private:
+    // ^Inode
+    virtual ssize_t read_bytes(Unix::off_t, size_t, byte* buffer, FileDescriptor*) override;
+    virtual InodeMetadata metadata() const override;
+    virtual bool traverse_as_directory(Function<bool(const FS::DirectoryEntry&)>) override;
+    virtual InodeIdentifier lookup(const String& name) override;
+    virtual String reverse_lookup(InodeIdentifier) override;
+    virtual void flush_metadata() override;
+    virtual ssize_t write_bytes(Unix::off_t, size_t, const byte* data, FileDescriptor*) override;
+    virtual bool add_child(InodeIdentifier child_id, const String& name, byte file_type, int& error) override;
+    virtual bool remove_child(const String& name, int& error) override;
+    virtual RetainPtr<Inode> parent() const override;
+    virtual int set_atime(Unix::time_t) override;
+    virtual int set_ctime(Unix::time_t) override;
+    virtual int set_mtime(Unix::time_t) override;
+    virtual int increment_link_count() override;
+    virtual int decrement_link_count() override;
+
+    void populate_lookup_cache();
+
+    Ext2FS& fs();
+    const Ext2FS& fs() const;
+    Ext2FSInode(Ext2FS&, unsigned index, const ext2_inode&);
+
+    Lock m_lock;
+    Vector<unsigned> m_block_list;
+    HashMap<String, unsigned> m_lookup_cache;
+    ext2_inode m_raw_inode;
+    mutable InodeIdentifier m_parent_id;
+};
+
+class Ext2FS final : public DiskBackedFS {
+    friend class Ext2FSInode;
+public:
+    static RetainPtr<Ext2FS> create(RetainPtr<DiskDevice>&&);
+    virtual ~Ext2FS() override;
+    virtual bool initialize() override;
+
+private:
+    typedef unsigned BlockIndex;
+    typedef unsigned GroupIndex;
+    typedef unsigned InodeIndex;
+    explicit Ext2FS(RetainPtr<DiskDevice>&&);
+
+    const ext2_super_block& super_block() const;
+    const ext2_group_desc& group_descriptor(unsigned groupIndex) const;
+    unsigned first_block_of_group(unsigned groupIndex) const;
+    unsigned inodes_per_block() const;
+    unsigned inodes_per_group() const;
+    unsigned blocks_per_group() const;
+    unsigned inode_size() const;
+
+    bool write_ext2_inode(unsigned, const ext2_inode&);
+    ByteBuffer read_block_containing_inode(unsigned inode, unsigned& blockIndex, unsigned& offset) const;
+
+    ByteBuffer read_super_block() const;
+    bool write_super_block(const ext2_super_block&);
+
+    virtual const char* class_name() const override;
+    virtual InodeIdentifier root_inode() const override;
+    virtual RetainPtr<Inode> create_inode(InodeIdentifier parentInode, const String& name, Unix::mode_t, unsigned size, int& error) override;
+    virtual RetainPtr<Inode> create_directory(InodeIdentifier parentInode, const String& name, Unix::mode_t, int& error) override;
+    virtual RetainPtr<Inode> get_inode(InodeIdentifier) const override;
+
+    unsigned allocate_inode(unsigned preferredGroup, unsigned expectedSize);
+    Vector<BlockIndex> allocate_blocks(unsigned group, unsigned count);
+    unsigned group_index_from_inode(unsigned) const;
+
+    Vector<unsigned> block_list_for_inode(const ext2_inode&, bool include_block_list_blocks = false) const;
+    bool write_block_list_for_inode(InodeIndex, ext2_inode&, const Vector<BlockIndex>&);
+
+    void dump_block_bitmap(unsigned groupIndex) const;
+    void dump_inode_bitmap(unsigned groupIndex) const;
+
+    template<typename F> void traverse_inode_bitmap(unsigned groupIndex, F) const;
+    template<typename F> void traverse_block_bitmap(unsigned groupIndex, F) const;
+
+    bool add_inode_to_directory(InodeIndex parent, InodeIndex child, const String& name, byte fileType, int& error);
+    bool write_directory_inode(unsigned directoryInode, Vector<DirectoryEntry>&&);
+    bool get_inode_allocation_state(InodeIndex) const;
+    bool set_inode_allocation_state(unsigned inode, bool);
+    bool set_block_allocation_state(GroupIndex, BlockIndex, bool);
+
+    void uncache_inode(InodeIndex);
+    void free_inode(Ext2FSInode&);
+
+    struct BlockListShape {
+        unsigned direct_blocks { 0 };
+        unsigned indirect_blocks { 0 };
+        unsigned doubly_indirect_blocks { 0 };
+        unsigned triply_indirect_blocks { 0 };
+        unsigned meta_blocks { 0 };
+    };
+
+    BlockListShape compute_block_list_shape(unsigned blocks);
+
+    unsigned m_blockGroupCount { 0 };
+
+    mutable ByteBuffer m_cached_super_block;
+    mutable ByteBuffer m_cached_group_descriptor_table;
+
+    mutable Lock m_inode_cache_lock;
+    mutable HashMap<BlockIndex, RetainPtr<Ext2FSInode>> m_inode_cache;
+};
+
+inline Ext2FS& Ext2FSInode::fs()
+{
+    return static_cast<Ext2FS&>(Inode::fs());
+}
+
+inline const Ext2FS& Ext2FSInode::fs() const
+{
+    return static_cast<const Ext2FS&>(Inode::fs());
+}
--- a/Kernel/FIFO.h
+++ b/Kernel/FIFO.h
@ -3,7 +3,7 @@
 #include "DoubleBuffer.h"
 #include <AK/Retainable.h>
 #include <AK/RetainPtr.h>
-#include <VirtualFileSystem/UnixTypes.h>
+#include <Kernel/UnixTypes.h>

 class FIFO : public Retainable<FIFO> {
 public:
--- a/Kernel/FileBackedDiskDevice.cpp
+++ b/Kernel/FileBackedDiskDevice.cpp
@ -0,0 +1,82 @@
+#define _FILE_OFFSET_BITS 64
+
+#include "FileBackedDiskDevice.h"
+#include <cstring>
+#include <sys/stat.h>
+
+//#define FBBD_DEBUG
+#define IGNORE_FILE_LENGTH // Useful for e.g /dev/hda2
+
+RetainPtr<FileBackedDiskDevice> FileBackedDiskDevice::create(String&& image_path, unsigned block_size)
+{
+    return adopt(*new FileBackedDiskDevice(move(image_path), block_size));
+}
+
+FileBackedDiskDevice::FileBackedDiskDevice(String&& image_path, unsigned block_size)
+    : m_image_path(move(image_path))
+    , m_block_size(block_size)
+{
+    struct stat st;
+    int result = stat(m_image_path.characters(), &st);
+    ASSERT(result != -1);
+    m_file_length = st.st_size;
+    m_file = fopen(m_image_path.characters(), "r+");
+}
+
+FileBackedDiskDevice::~FileBackedDiskDevice()
+{
+}
+
+unsigned FileBackedDiskDevice::block_size() const
+{
+    return m_block_size;
+}
+
+bool FileBackedDiskDevice::read_block(unsigned index, byte* out) const
+{
+    DiskOffset offset = index * m_block_size;
+    return read_internal(offset, block_size(), out);
+}
+
+bool FileBackedDiskDevice::write_block(unsigned index, const byte* data)
+{
+    DiskOffset offset = index * m_block_size;
+    return write_internal(offset, block_size(), data);
+}
+
+bool FileBackedDiskDevice::read_internal(DiskOffset offset, unsigned length, byte* out) const
+{
+#ifndef IGNORE_FILE_LENGTH
+    if (offset + length >= m_fileLength)
+        return false;
+#endif
+#ifdef FBBD_DEBUG
+    printf("[FileBackedDiskDevice] Read device @ offset %llx, length %u\n", offset, length);
+#endif
+    fseeko(m_file, offset, SEEK_SET);
+    unsigned nread = fread(out, sizeof(byte), length, m_file);
+    ASSERT(nread == length);
+    return true;
+}
+
+bool FileBackedDiskDevice::write_internal(DiskOffset offset, unsigned length, const byte* data)
+{
+#ifndef IGNORE_FILE_LENGTH
+    if (offset + length >= m_fileLength)
+        return false;
+#endif
+#ifdef FBBD_DEBUG
+    printf("[FileBackedDiskDevice] Write device @ offset %llx, length %u\n", offset, length);
+#endif
+    fseeko(m_file, offset, SEEK_SET);
+    // size_t fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream);
+    unsigned nwritten = fwrite(data, sizeof(byte), length, m_file);
+    ASSERT(nwritten == length);
+    return true;
+}
+
+const char* FileBackedDiskDevice::class_name() const
+{
+    return "FileBackedDiskDevice";
+}
+
--- a/Kernel/FileBackedDiskDevice.h
+++ b/Kernel/FileBackedDiskDevice.h
@ -0,0 +1,33 @@
+#pragma once
+
+#include "DiskDevice.h"
+#include <AK/RetainPtr.h>
+#include <AK/AKString.h>
+#include <AK/Types.h>
+#include <stdio.h>
+
+class FileBackedDiskDevice final : public DiskDevice {
+public:
+    static RetainPtr<FileBackedDiskDevice> create(String&& image_path, unsigned block_size);
+    virtual ~FileBackedDiskDevice() override;
+
+    bool is_valid() const { return m_file; }
+
+    virtual unsigned block_size() const override;
+    virtual bool read_block(unsigned index, byte* out) const override;
+    virtual bool write_block(unsigned index, const byte*) override;
+
+private:
+    virtual const char* class_name() const override;
+
+    bool read_internal(DiskOffset, unsigned length, byte* out) const;
+    bool write_internal(DiskOffset, unsigned length, const byte* data);
+
+    FileBackedDiskDevice(String&& imagePath, unsigned block_size);
+
+    String m_image_path;
+    FILE* m_file { nullptr };
+    DiskOffset m_file_length { 0 };
+    unsigned m_block_size { 0 };
+};
+
--- a/Kernel/FileDescriptor.cpp
+++ b/Kernel/FileDescriptor.cpp
@ -0,0 +1,322 @@
+#include "FileDescriptor.h"
+#include "FileSystem.h"
+#include "CharacterDevice.h"
+#include <LibC/errno_numbers.h>
+#include "UnixTypes.h"
+#include <AK/BufferStream.h>
+#include "FIFO.h"
+#include "TTY.h"
+#include "MasterPTY.h"
+
+RetainPtr<FileDescriptor> FileDescriptor::create(RetainPtr<Inode>&& inode)
+{
+    return adopt(*new FileDescriptor(move(inode)));
+}
+
+RetainPtr<FileDescriptor> FileDescriptor::create(RetainPtr<CharacterDevice>&& device)
+{
+    return adopt(*new FileDescriptor(move(device)));
+}
+
+RetainPtr<FileDescriptor> FileDescriptor::create_pipe_writer(FIFO& fifo)
+{
+    return adopt(*new FileDescriptor(fifo, FIFO::Writer));
+}
+
+RetainPtr<FileDescriptor> FileDescriptor::create_pipe_reader(FIFO& fifo)
+{
+    return adopt(*new FileDescriptor(fifo, FIFO::Reader));
+}
+
+FileDescriptor::FileDescriptor(RetainPtr<Inode>&& inode)
+    : m_inode(move(inode))
+{
+}
+
+FileDescriptor::FileDescriptor(RetainPtr<CharacterDevice>&& device)
+    : m_device(move(device))
+{
+}
+
+FileDescriptor::~FileDescriptor()
+{
+    if (m_fifo)
+        m_fifo->close(fifo_direction());
+}
+
+RetainPtr<FileDescriptor> FileDescriptor::clone()
+{
+    RetainPtr<FileDescriptor> descriptor;
+    if (is_fifo()) {
+        descriptor = fifo_direction() == FIFO::Reader
+            ? FileDescriptor::create_pipe_reader(*m_fifo)
+            : FileDescriptor::create_pipe_writer(*m_fifo);
+    } else {
+        if (m_inode)
+            descriptor = FileDescriptor::create(m_inode.copyRef());
+        else {
+            descriptor = FileDescriptor::create(m_device.copyRef());
+        }
+    }
+    if (!descriptor)
+        return nullptr;
+    descriptor->m_current_offset = m_current_offset;
+    descriptor->m_is_blocking = m_is_blocking;
+    descriptor->m_file_flags = m_file_flags;
+    return descriptor;
+}
+
+bool additionWouldOverflow(Unix::off_t a, Unix::off_t b)
+{
+    ASSERT(a > 0);
+    uint64_t ua = a;
+    return (ua + b) > maxFileOffset;
+}
+
+int FileDescriptor::stat(Unix::stat* buffer)
+{
+    ASSERT(!is_fifo());
+    if (!m_inode && !m_device)
+        return -EBADF;
+
+    auto metadata = this->metadata();
+    if (!metadata.isValid())
+        return -EIO;
+
+    buffer->st_dev = 0; // FIXME
+    buffer->st_ino = metadata.inode.index();
+    buffer->st_mode = metadata.mode;
+    buffer->st_nlink = metadata.linkCount;
+    buffer->st_uid = metadata.uid;
+    buffer->st_gid = metadata.gid;
+    buffer->st_rdev = 0; // FIXME
+    buffer->st_size = metadata.size;
+    buffer->st_blksize = metadata.blockSize;
+    buffer->st_blocks = metadata.blockCount;
+    buffer->st_atime = metadata.atime;
+    buffer->st_mtime = metadata.mtime;
+    buffer->st_ctime = metadata.ctime;
+    return 0;
+}
+
+Unix::off_t FileDescriptor::seek(Unix::off_t offset, int whence)
+{
+    ASSERT(!is_fifo());
+    if (!m_inode && !m_device)
+        return -EBADF;
+
+    // FIXME: The file type should be cached on the vnode.
+    //        It's silly that we have to do a full metadata lookup here.
+    auto metadata = this->metadata();
+    if (!metadata.isValid())
+        return -EIO;
+
+    if (metadata.isSocket() || metadata.isFIFO())
+        return -ESPIPE;
+
+    Unix::off_t newOffset;
+
+    switch (whence) {
+    case SEEK_SET:
+        newOffset = offset;
+        break;
+    case SEEK_CUR:
+        newOffset = m_current_offset + offset;
+#ifndef SERENITY
+        if (additionWouldOverflow(m_currentOffset, offset))
+            return -EOVERFLOW;
+#endif
+        if (newOffset < 0)
+            return -EINVAL;
+        break;
+    case SEEK_END:
+        ASSERT(metadata.size); // FIXME: What do I do?
+        newOffset = metadata.size;
+        break;
+    default:
+        return -EINVAL;
+    }
+
+    m_current_offset = newOffset;
+    return m_current_offset;
+}
+
+ssize_t FileDescriptor::read(Process& process, byte* buffer, size_t count)
+{
+    if (is_fifo()) {
+        ASSERT(fifo_direction() == FIFO::Reader);
+        return m_fifo->read(buffer, count);
+    }
+    if (m_device) {
+        // FIXME: What should happen to m_currentOffset?
+        return m_device->read(process, buffer, count);
+    }
+    ASSERT(inode());
+    ssize_t nread = inode()->read_bytes(m_current_offset, count, buffer, this);
+    m_current_offset += nread;
+    return nread;
+}
+
+ssize_t FileDescriptor::write(Process& process, const byte* data, size_t size)
+{
+    if (is_fifo()) {
+        ASSERT(fifo_direction() == FIFO::Writer);
+        return m_fifo->write(data, size);
+    }
+    if (m_device) {
+        // FIXME: What should happen to m_currentOffset?
+        return m_device->write(process, data, size);
+    }
+    ASSERT(m_inode);
+    ssize_t nwritten = m_inode->write_bytes(m_current_offset, size, data, this);
+    m_current_offset += nwritten;
+    return nwritten;
+}
+
+bool FileDescriptor::can_write(Process& process)
+{
+    if (is_fifo()) {
+        ASSERT(fifo_direction() == FIFO::Writer);
+        return m_fifo->can_write();
+    }
+    if (m_device)
+        return m_device->can_write(process);
+    return true;
+}
+
+bool FileDescriptor::can_read(Process& process)
+{
+    if (is_fifo()) {
+        ASSERT(fifo_direction() == FIFO::Reader);
+        return m_fifo->can_read();
+    }
+    if (m_device)
+        return m_device->can_read(process);
+    return true;
+}
+
+ByteBuffer FileDescriptor::read_entire_file(Process& process)
+{
+    ASSERT(!is_fifo());
+
+    if (m_device) {
+        auto buffer = ByteBuffer::create_uninitialized(1024);
+        ssize_t nread = m_device->read(process, buffer.pointer(), buffer.size());
+        buffer.trim(nread);
+        return buffer;
+    }
+
+    ASSERT(m_inode);
+    return m_inode->read_entire(this);
+}
+
+bool FileDescriptor::is_directory() const
+{
+    ASSERT(!is_fifo());
+    return metadata().isDirectory();
+}
+
+ssize_t FileDescriptor::get_dir_entries(byte* buffer, size_t size)
+{
+    auto metadata = this->metadata();
+    if (!metadata.isValid())
+        return -EIO;
+    if (!metadata.isDirectory())
+        return -ENOTDIR;
+
+    // FIXME: Compute the actual size needed.
+    auto tempBuffer = ByteBuffer::create_uninitialized(2048);
+    BufferStream stream(tempBuffer);
+    VFS::the().traverse_directory_inode(*m_inode, [&stream] (auto& entry) {
+        stream << (dword)entry.inode.index();
+        stream << (byte)entry.fileType;
+        stream << (dword)entry.name_length;
+        stream << entry.name;
+        return true;
+    });
+
+    if (size < stream.offset())
+        return -1;
+
+    memcpy(buffer, tempBuffer.pointer(), stream.offset());
+    return stream.offset();
+}
+
+bool FileDescriptor::is_tty() const
+{
+    return m_device && m_device->is_tty();
+}
+
+const TTY* FileDescriptor::tty() const
+{
+    if (!is_tty())
+        return nullptr;
+    return static_cast<const TTY*>(m_device.ptr());
+}
+
+TTY* FileDescriptor::tty()
+{
+    if (!is_tty())
+        return nullptr;
+    return static_cast<TTY*>(m_device.ptr());
+}
+
+bool FileDescriptor::is_master_pty() const
+{
+    if (m_device)
+        return m_device->is_master_pty();
+    return false;
+}
+
+const MasterPTY* FileDescriptor::master_pty() const
+{
+    if (!is_master_pty())
+        return nullptr;
+    return static_cast<const MasterPTY*>(m_device.ptr());
+}
+
+MasterPTY* FileDescriptor::master_pty()
+{
+    if (!is_master_pty())
+        return nullptr;
+    return static_cast<MasterPTY*>(m_device.ptr());
+}
+
+int FileDescriptor::close()
+{
+    return 0;
+}
+
+String FileDescriptor::absolute_path()
+{
+    Stopwatch sw("absolute_path");
+    if (is_tty())
+        return tty()->tty_name();
+    if (is_fifo()) {
+        char buf[32];
+        ksprintf(buf, "fifo:%x", m_fifo.ptr());
+        return buf;
+    }
+    if (is_character_device()) {
+        char buf[128];
+        ksprintf(buf, "device:%u,%u (%s)", m_device->major(), m_device->minor(), m_device->class_name());
+        return buf;
+    }
+    ASSERT(m_inode);
+    return VFS::the().absolute_path(*m_inode);
+}
+
+FileDescriptor::FileDescriptor(FIFO& fifo, FIFO::Direction direction)
+    : m_is_blocking(true)
+    , m_fifo(fifo)
+    , m_fifo_direction(direction)
+{
+    m_fifo->open(direction);
+}
+
+InodeMetadata FileDescriptor::metadata() const
+{
+    if (m_inode)
+        return m_inode->metadata();
+    return { };
+}
--- a/Kernel/FileDescriptor.h
+++ b/Kernel/FileDescriptor.h
@ -0,0 +1,90 @@
+#pragma once
+
+#include "VirtualFileSystem.h"
+#include "InodeMetadata.h"
+#include "FIFO.h"
+#include <AK/ByteBuffer.h>
+#include <AK/CircularQueue.h>
+#include <AK/Retainable.h>
+
+class TTY;
+class MasterPTY;
+class Process;
+
+class FileDescriptor : public Retainable<FileDescriptor> {
+public:
+    static RetainPtr<FileDescriptor> create(RetainPtr<Inode>&&);
+    static RetainPtr<FileDescriptor> create(RetainPtr<CharacterDevice>&&);
+    static RetainPtr<FileDescriptor> create_pipe_writer(FIFO&);
+    static RetainPtr<FileDescriptor> create_pipe_reader(FIFO&);
+    ~FileDescriptor();
+
+    RetainPtr<FileDescriptor> clone();
+
+    int close();
+
+    Unix::off_t seek(Unix::off_t, int whence);
+    ssize_t read(Process&, byte*, size_t);
+    ssize_t write(Process&, const byte* data, size_t);
+    int stat(Unix::stat*);
+
+    bool can_read(Process&);
+    bool can_write(Process&);
+
+    ssize_t get_dir_entries(byte* buffer, size_t);
+
+    ByteBuffer read_entire_file(Process&);
+
+    String absolute_path();
+
+    bool is_directory() const;
+
+    bool is_character_device() const { return m_device.ptr(); }
+    CharacterDevice* character_device() { return m_device.ptr(); }
+    const CharacterDevice* character_device() const { return m_device.ptr(); }
+
+    bool is_tty() const;
+    const TTY* tty() const;
+    TTY* tty();
+
+    bool is_master_pty() const;
+    const MasterPTY* master_pty() const;
+    MasterPTY* master_pty();
+
+    InodeMetadata metadata() const;
+    Inode* inode() { return m_inode.ptr(); }
+    const Inode* inode() const { return m_inode.ptr(); }
+
+    bool supports_mmap() const { return m_inode && !m_device; }
+
+    bool is_blocking() const { return m_is_blocking; }
+    void set_blocking(bool b) { m_is_blocking = b; }
+
+    dword file_flags() const { return m_file_flags; }
+    void set_file_flags(dword flags) { m_file_flags = flags; }
+
+    bool is_fifo() const { return m_fifo; }
+    FIFO::Direction fifo_direction() { return m_fifo_direction; }
+
+    ByteBuffer& generator_cache() { return m_generator_cache; }
+
+private:
+    friend class VFS;
+    explicit FileDescriptor(RetainPtr<Inode>&&);
+    explicit FileDescriptor(RetainPtr<CharacterDevice>&&);
+    FileDescriptor(FIFO&, FIFO::Direction);
+
+    RetainPtr<Inode> m_inode;
+    RetainPtr<CharacterDevice> m_device;
+
+    Unix::off_t m_current_offset { 0 };
+
+    ByteBuffer m_generator_cache;
+
+    bool m_is_blocking { true };
+    dword m_file_flags { 0 };
+
+    RetainPtr<FIFO> m_fifo;
+    FIFO::Direction m_fifo_direction { FIFO::Neither };
+};
+
--- a/Kernel/FileSystem.cpp
+++ b/Kernel/FileSystem.cpp
@ -0,0 +1,151 @@
+#include <AK/Assertions.h>
+#include <AK/HashMap.h>
+#include <LibC/errno_numbers.h>
+#include "FileSystem.h"
+#include "MemoryManager.h"
+
+static dword s_lastFileSystemID;
+static HashMap<dword, FS*>* s_fs_map;
+static HashTable<Inode*>* s_inode_set;
+
+static HashMap<dword, FS*>& all_fses()
+{
+    if (!s_fs_map)
+        s_fs_map = new HashMap<dword, FS*>();
+    return *s_fs_map;
+}
+
+HashTable<Inode*>& all_inodes()
+{
+    if (!s_inode_set)
+        s_inode_set = new HashTable<Inode*>();
+    return *s_inode_set;
+}
+
+void FS::initialize_globals()
+{
+    s_lastFileSystemID = 0;
+    s_fs_map = nullptr;
+    s_inode_set = nullptr;
+}
+
+FS::FS()
+    : m_fsid(++s_lastFileSystemID)
+{
+    all_fses().set(m_fsid, this);
+}
+
+FS::~FS()
+{
+    all_fses().remove(m_fsid);
+}
+
+FS* FS::from_fsid(dword id)
+{
+    auto it = all_fses().find(id);
+    if (it != all_fses().end())
+        return (*it).value;
+    return nullptr;
+}
+
+ByteBuffer Inode::read_entire(FileDescriptor* descriptor)
+{
+    size_t initial_size = metadata().size ? metadata().size : 4096;
+    auto contents = ByteBuffer::create_uninitialized(initial_size);
+
+    ssize_t nread;
+    byte buffer[4096];
+    byte* out = contents.pointer();
+    Unix::off_t offset = 0;
+    for (;;) {
+        nread = read_bytes(offset, sizeof(buffer), buffer, descriptor);
+        ASSERT(nread <= (ssize_t)sizeof(buffer));
+        if (nread <= 0)
+            break;
+        memcpy(out, buffer, nread);
+        out += nread;
+        offset += nread;
+        ASSERT(offset <= (ssize_t)initial_size); // FIXME: Support dynamically growing the buffer.
+    }
+    if (nread < 0) {
+        kprintf("Inode::read_entire: ERROR: %d\n", nread);
+        return nullptr;
+    }
+
+    contents.trim(offset);
+    return contents;
+}
+
+FS::DirectoryEntry::DirectoryEntry(const char* n, InodeIdentifier i, byte ft)
+    : name_length(strlen(n))
+    , inode(i)
+    , fileType(ft)
+{
+    memcpy(name, n, name_length);
+    name[name_length] = '\0';
+}
+
+FS::DirectoryEntry::DirectoryEntry(const char* n, size_t nl, InodeIdentifier i, byte ft)
+    : name_length(nl)
+    , inode(i)
+    , fileType(ft)
+{
+    memcpy(name, n, nl);
+    name[nl] = '\0';
+}
+
+Inode::Inode(FS& fs, unsigned index)
+    : m_fs(fs)
+    , m_index(index)
+{
+    all_inodes().set(this);
+}
+
+Inode::~Inode()
+{
+    all_inodes().remove(this);
+}
+
+void Inode::will_be_destroyed()
+{
+    if (m_metadata_dirty)
+        flush_metadata();
+}
+
+int Inode::set_atime(Unix::time_t)
+{
+    return -ENOTIMPL;
+}
+
+int Inode::set_ctime(Unix::time_t)
+{
+    return -ENOTIMPL;
+}
+
+int Inode::set_mtime(Unix::time_t)
+{
+    return -ENOTIMPL;
+}
+
+int Inode::increment_link_count()
+{
+    return -ENOTIMPL;
+}
+
+int Inode::decrement_link_count()
+{
+    return -ENOTIMPL;
+}
+
+void FS::sync()
+{
+    for (auto* inode : all_inodes()) {
+        if (inode->is_metadata_dirty())
+            inode->flush_metadata();
+    }
+}
+
+void Inode::set_vmo(RetainPtr<VMObject>&& vmo)
+{
+    m_vmo = move(vmo);
+}
--- a/Kernel/FileSystem.h
+++ b/Kernel/FileSystem.h
@ -0,0 +1,148 @@
+#pragma once
+
+#include "DiskDevice.h"
+#include "InodeIdentifier.h"
+#include "InodeMetadata.h"
+#include "Limits.h"
+#include "UnixTypes.h"
+#include <AK/ByteBuffer.h>
+#include <AK/HashMap.h>
+#include <AK/OwnPtr.h>
+#include <AK/Retainable.h>
+#include <AK/RetainPtr.h>
+#include <AK/AKString.h>
+#include <AK/Function.h>
+#include <AK/kstdio.h>
+
+static const dword mepoch = 476763780;
+
+class Inode;
+class FileDescriptor;
+class VMObject;
+
+class FS : public Retainable<FS> {
+public:
+    static void initialize_globals();
+    virtual ~FS();
+
+    dword id() const { return m_fsid; }
+    static FS* from_fsid(dword);
+    static void sync();
+
+    virtual bool initialize() = 0;
+    virtual const char* class_name() const = 0;
+    virtual InodeIdentifier root_inode() const = 0;
+
+    bool is_readonly() const { return m_readonly; }
+
+    struct DirectoryEntry {
+        DirectoryEntry(const char* name, InodeIdentifier, byte fileType);
+        DirectoryEntry(const char* name, size_t name_length, InodeIdentifier, byte fileType);
+        char name[256];
+        size_t name_length { 0 };
+        InodeIdentifier inode;
+        byte fileType { 0 };
+    };
+
+    virtual RetainPtr<Inode> create_inode(InodeIdentifier parentInode, const String& name, Unix::mode_t, unsigned size, int& error) = 0;
+    virtual RetainPtr<Inode> create_directory(InodeIdentifier parentInode, const String& name, Unix::mode_t, int& error) = 0;
+
+    virtual RetainPtr<Inode> get_inode(InodeIdentifier) const = 0;
+
+protected:
+    FS();
+
+private:
+    dword m_fsid { 0 };
+    bool m_readonly { false };
+};
+
+class Inode : public Retainable<Inode> {
+    friend class VFS;
+public:
+    virtual ~Inode();
+
+    virtual void one_retain_left() { }
+
+    FS& fs() { return m_fs; }
+    const FS& fs() const { return m_fs; }
+    unsigned fsid() const;
+    unsigned index() const { return m_index; }
+
+    size_t size() const { return metadata().size; }
+    bool is_symlink() const { return metadata().isSymbolicLink(); }
+    bool is_directory() const { return metadata().isDirectory(); }
+    bool is_character_device() const { return metadata().isCharacterDevice(); }
+
+    InodeIdentifier identifier() const { return { fsid(), index() }; }
+    virtual InodeMetadata metadata() const = 0;
+
+    ByteBuffer read_entire(FileDescriptor* = nullptr);
+
+    virtual ssize_t read_bytes(Unix::off_t, size_t, byte* buffer, FileDescriptor*) = 0;
+    virtual bool traverse_as_directory(Function<bool(const FS::DirectoryEntry&)>) = 0;
+    virtual InodeIdentifier lookup(const String& name) = 0;
+    virtual String reverse_lookup(InodeIdentifier) = 0;
+    virtual ssize_t write_bytes(Unix::off_t, size_t, const byte* data, FileDescriptor*) = 0;
+    virtual bool add_child(InodeIdentifier child_id, const String& name, byte file_type, int& error) = 0;
+    virtual bool remove_child(const String& name, int& error) = 0;
+    virtual RetainPtr<Inode> parent() const = 0;
+
+    bool is_metadata_dirty() const { return m_metadata_dirty; }
+
+    virtual int set_atime(Unix::time_t);
+    virtual int set_ctime(Unix::time_t);
+    virtual int set_mtime(Unix::time_t);
+    virtual int increment_link_count();
+    virtual int decrement_link_count();
+
+    virtual void flush_metadata() = 0;
+
+    void will_be_destroyed();
+
+    void set_vmo(RetainPtr<VMObject>&&);
+    VMObject* vmo() { return m_vmo.ptr(); }
+    const VMObject* vmo() const { return m_vmo.ptr(); }
+
+protected:
+    Inode(FS& fs, unsigned index);
+
+    void set_metadata_dirty(bool b) { m_metadata_dirty = b; }
+private:
+    FS& m_fs;
+    unsigned m_index { 0 };
+    RetainPtr<VMObject> m_vmo;
+    bool m_metadata_dirty { false };
+};
+
+inline FS* InodeIdentifier::fs()
+{
+    return FS::from_fsid(m_fsid);
+}
+
+inline const FS* InodeIdentifier::fs() const
+{
+    return FS::from_fsid(m_fsid);
+}
+
+inline bool InodeIdentifier::is_root_inode() const
+{
+    return (*this) == fs()->root_inode();
+}
+
+inline unsigned Inode::fsid() const
+{
+    return m_fs.id();
+}
+
+namespace AK {
+
+template<>
+struct Traits<InodeIdentifier> {
+    // FIXME: This is a shitty hash.
+    static unsigned hash(const InodeIdentifier& inode) { return Traits<unsigned>::hash(inode.fsid()) + Traits<unsigned>::hash(inode.index()); }
+    static void dump(const InodeIdentifier& inode) { kprintf("%02u:%08u", inode.fsid(), inode.index()); }
+};
+
+}
+
--- a/Kernel/FullDevice.cpp
+++ b/Kernel/FullDevice.cpp
@ -0,0 +1,34 @@
+#include "FullDevice.h"
+#include "Limits.h"
+#include <LibC/errno_numbers.h>
+#include <AK/StdLibExtras.h>
+#include <AK/kstdio.h>
+
+FullDevice::FullDevice()
+    : CharacterDevice(1, 7)
+{
+}
+
+FullDevice::~FullDevice()
+{
+}
+
+bool FullDevice::can_read(Process&) const
+{
+    return true;
+}
+
+ssize_t FullDevice::read(Process&, byte* buffer, size_t bufferSize)
+{
+    size_t count = min(GoodBufferSize, bufferSize);
+    memset(buffer, 0, count);
+    return count;
+}
+
+ssize_t FullDevice::write(Process&, const byte*, size_t bufferSize)
+{
+    if (bufferSize == 0)
+        return 0;
+    return -ENOSPC;
+}
+
--- a/Kernel/FullDevice.h
+++ b/Kernel/FullDevice.h
@ -0,0 +1,19 @@
+#pragma once
+
+#include "CharacterDevice.h"
+
+class FullDevice final : public CharacterDevice {
+    AK_MAKE_ETERNAL
+public:
+    FullDevice();
+    virtual ~FullDevice() override;
+
+private:
+    // ^CharacterDevice
+    virtual ssize_t read(Process&, byte* buffer, size_t bufferSize) override;
+    virtual ssize_t write(Process&, const byte* buffer, size_t bufferSize) override;
+    virtual bool can_read(Process&) const override;
+    virtual bool can_write(Process&) const override { return true; }
+    virtual const char* class_name() const override { return "FullDevice"; }
+};
+
--- a/Kernel/GUIEventDevice.h
+++ b/Kernel/GUIEventDevice.h
@ -1,6 +1,6 @@
 #pragma once

-#include <VirtualFileSystem/CharacterDevice.h>
+#include <Kernel/CharacterDevice.h>

 class GUIEventDevice final : public CharacterDevice {
 public:
--- a/Kernel/IDEDiskDevice.h
+++ b/Kernel/IDEDiskDevice.h
@ -2,7 +2,7 @@

 #include <AK/Lock.h>
 #include <AK/RetainPtr.h>
-#include <VirtualFileSystem/DiskDevice.h>
+#include <Kernel/DiskDevice.h>
 #include "IRQHandler.h"

 class IDEDiskDevice final : public IRQHandler, public DiskDevice {
--- a/Kernel/InodeIdentifier.h
+++ b/Kernel/InodeIdentifier.h
@ -0,0 +1,42 @@
+#pragma once
+
+#include <AK/ByteBuffer.h>
+#include <AK/Types.h>
+
+class FS;
+struct InodeMetadata;
+
+class InodeIdentifier {
+public:
+    InodeIdentifier() { }
+    InodeIdentifier(dword fileSystemID, dword inode)
+        : m_fsid(fileSystemID)
+        , m_index(inode)
+    {
+    }
+
+    bool is_valid() const { return m_fsid != 0 && m_index != 0; }
+
+    dword fsid() const { return m_fsid; }
+    dword index() const { return m_index; }
+
+    FS* fs();
+    const FS* fs() const;
+
+    bool operator==(const InodeIdentifier& other) const
+    {
+        return m_fsid == other.m_fsid && m_index == other.m_index;
+    }
+
+    bool operator!=(const InodeIdentifier& other) const
+    {
+        return m_fsid != other.m_fsid || m_index != other.m_index;
+    }
+
+    bool is_root_inode() const;
+
+private:
+    dword m_fsid { 0 };
+    dword m_index { 0 };
+};
+
--- a/Kernel/InodeMetadata.h
+++ b/Kernel/InodeMetadata.h
@ -0,0 +1,57 @@
+#pragma once
+
+#include "InodeIdentifier.h"
+#include "UnixTypes.h"
+#include <AK/HashTable.h>
+
+inline bool isDirectory(Unix::mode_t mode) { return (mode & 0170000) == 0040000; }
+inline bool isCharacterDevice(Unix::mode_t mode) { return (mode & 0170000) == 0020000; }
+inline bool isBlockDevice(Unix::mode_t mode) { return (mode & 0170000) == 0060000; }
+inline bool isRegularFile(Unix::mode_t mode) { return (mode & 0170000) == 0100000; }
+inline bool isFIFO(Unix::mode_t mode) { return (mode & 0170000) == 0010000; }
+inline bool isSymbolicLink(Unix::mode_t mode) { return (mode & 0170000) == 0120000; }
+inline bool isSocket(Unix::mode_t mode) { return (mode & 0170000) == 0140000; }
+inline bool isSticky(Unix::mode_t mode) { return mode & 01000; }
+inline bool isSetUID(Unix::mode_t mode) { return mode & 04000; }
+inline bool isSetGID(Unix::mode_t mode) { return mode & 02000; }
+
+struct InodeMetadata {
+    bool isValid() const { return inode.is_valid(); }
+
+    bool mayExecute(uid_t u, const HashTable<gid_t>& g) const
+    {
+        if (uid == u)
+            return mode & 0100;
+        if (g.contains(gid))
+            return mode & 0010;
+        return mode & 0001;
+    }
+
+    bool isDirectory() const { return ::isDirectory(mode); }
+    bool isCharacterDevice() const { return ::isCharacterDevice(mode); }
+    bool isBlockDevice() const { return ::isBlockDevice(mode); }
+    bool isRegularFile() const { return ::isRegularFile(mode); }
+    bool isFIFO() const { return ::isFIFO(mode); }
+    bool isSymbolicLink() const { return ::isSymbolicLink(mode); }
+    bool isSocket() const { return ::isSocket(mode); }
+    bool isSticky() const { return ::isSticky(mode); }
+    bool isSetUID() const { return ::isSetUID(mode); }
+    bool isSetGID() const { return ::isSetGID(mode); }
+
+    InodeIdentifier inode;
+    Unix::off_t size { 0 };
+    Unix::mode_t mode { 0 };
+    Unix::uid_t uid { 0 };
+    Unix::gid_t gid { 0 };
+    Unix::nlink_t linkCount { 0 };
+    Unix::time_t atime { 0 };
+    Unix::time_t ctime { 0 };
+    Unix::time_t mtime { 0 };
+    Unix::time_t dtime { 0 };
+    Unix::blkcnt_t blockCount { 0 };
+    Unix::blksize_t blockSize { 0 };
+    unsigned majorDevice { 0 };
+    unsigned minorDevice { 0 };
+};
+
+
--- a/Kernel/Keyboard.h
+++ b/Kernel/Keyboard.h
@ -3,7 +3,7 @@
 #include <AK/Types.h>
 #include <AK/DoublyLinkedList.h>
 #include <AK/CircularQueue.h>
-#include <VirtualFileSystem/CharacterDevice.h>
+#include <Kernel/CharacterDevice.h>
 #include "IRQHandler.h"

 class KeyboardClient;
--- a/Kernel/Limits.h
+++ b/Kernel/Limits.h
@ -0,0 +1,9 @@
+#pragma once
+
+#include "UnixTypes.h"
+
+inline static const Unix::off_t maxFileOffset = 2147483647;
+
+static const size_t GoodBufferSize = 4096;
+
+
--- a/Kernel/Makefile
+++ b/Kernel/Makefile
@ -33,18 +33,18 @@ KERNEL_OBJS = \
       GUIEventDevice.o

 VFS_OBJS = \
-    ../VirtualFileSystem/DiskDevice.o \
-    ../VirtualFileSystem/CharacterDevice.o \
-    ../VirtualFileSystem/NullDevice.o \
-    ../VirtualFileSystem/FullDevice.o \
-    ../VirtualFileSystem/ZeroDevice.o \
-    ../VirtualFileSystem/RandomDevice.o \
-    ../VirtualFileSystem/FileSystem.o \
-    ../VirtualFileSystem/DiskBackedFileSystem.o \
-    ../VirtualFileSystem/Ext2FileSystem.o \
-    ../VirtualFileSystem/VirtualFileSystem.o \
-    ../VirtualFileSystem/FileDescriptor.o \
-    ../VirtualFileSystem/SyntheticFileSystem.o
+    DiskDevice.o \
+    CharacterDevice.o \
+    NullDevice.o \
+    FullDevice.o \
+    ZeroDevice.o \
+    RandomDevice.o \
+    FileSystem.o \
+    DiskBackedFileSystem.o \
+    Ext2FileSystem.o \
+    VirtualFileSystem.o \
+    FileDescriptor.o \
+    SyntheticFileSystem.o

 SHAREDGRAPHICS_OBJS = \
    ../SharedGraphics/Rect.o \
--- a/Kernel/MasterPTY.h
+++ b/Kernel/MasterPTY.h
@ -1,6 +1,6 @@
 #pragma once

-#include <VirtualFileSystem/CharacterDevice.h>
+#include <Kernel/CharacterDevice.h>
 #include "DoubleBuffer.h"

 class SlavePTY;
--- a/Kernel/MemoryManager.h
+++ b/Kernel/MemoryManager.h
@ -9,7 +9,7 @@
 #include <AK/Vector.h>
 #include <AK/HashTable.h>
 #include <AK/AKString.h>
-#include <VirtualFileSystem/VirtualFileSystem.h>
+#include <Kernel/VirtualFileSystem.h>

 #define PAGE_ROUND_UP(x) ((((dword)(x)) + PAGE_SIZE-1) & (~(PAGE_SIZE-1)))

--- a/Kernel/NullDevice.cpp
+++ b/Kernel/NullDevice.cpp
@ -0,0 +1,29 @@
+#include "NullDevice.h"
+#include "Limits.h"
+#include <AK/StdLibExtras.h>
+#include <AK/kstdio.h>
+
+NullDevice::NullDevice()
+    : CharacterDevice(1, 3)
+{
+}
+
+NullDevice::~NullDevice()
+{
+}
+
+bool NullDevice::can_read(Process&) const
+{
+    return true;
+}
+
+ssize_t NullDevice::read(Process&, byte*, size_t)
+{
+    return 0;
+}
+
+ssize_t NullDevice::write(Process&, const byte*, size_t bufferSize)
+{
+    return min(GoodBufferSize, bufferSize);
+}
+
--- a/Kernel/NullDevice.h
+++ b/Kernel/NullDevice.h
@ -0,0 +1,19 @@
+#pragma once
+
+#include "CharacterDevice.h"
+
+class NullDevice final : public CharacterDevice {
+    AK_MAKE_ETERNAL
+public:
+    NullDevice();
+    virtual ~NullDevice() override;
+
+private:
+    // ^CharacterDevice
+    virtual ssize_t read(Process&, byte* buffer, size_t bufferSize) override;
+    virtual ssize_t write(Process&, const byte* buffer, size_t bufferSize) override;
+    virtual bool can_write(Process&) const override { return true; }
+    virtual bool can_read(Process&) const override;
+    virtual const char* class_name() const override { return "CharacterDevice"; }
+};
+
--- a/Kernel/PS2MouseDevice.h
+++ b/Kernel/PS2MouseDevice.h
@ -1,6 +1,6 @@
 #pragma once

-#include <VirtualFileSystem/CharacterDevice.h>
+#include <Kernel/CharacterDevice.h>
 #include "IRQHandler.h"

 class PS2MouseDevice final : public IRQHandler, public CharacterDevice {
--- a/Kernel/PTYMultiplexer.h
+++ b/Kernel/PTYMultiplexer.h
@ -1,6 +1,6 @@
 #pragma once

-#include <VirtualFileSystem/CharacterDevice.h>
+#include <Kernel/CharacterDevice.h>
 #include <AK/Lock.h>

 class MasterPTY;
--- a/Kernel/ProcFileSystem.cpp
+++ b/Kernel/ProcFileSystem.cpp
@ -1,6 +1,6 @@
 #include "ProcFileSystem.h"
 #include "Process.h"
-#include <VirtualFileSystem/VirtualFileSystem.h>
+#include <Kernel/VirtualFileSystem.h>
 #include "system.h"
 #include "MemoryManager.h"
 #include "StdLib.h"
--- a/Kernel/ProcFileSystem.h
+++ b/Kernel/ProcFileSystem.h
@ -1,7 +1,7 @@
 #pragma once

 #include <AK/Types.h>
-#include <VirtualFileSystem/SyntheticFileSystem.h>
+#include <Kernel/SyntheticFileSystem.h>

 class Process;

--- a/Kernel/Process.cpp
+++ b/Kernel/Process.cpp
@ -4,8 +4,8 @@
 #include "StdLib.h"
 #include "i386.h"
 #include "system.h"
-#include <VirtualFileSystem/FileDescriptor.h>
-#include <VirtualFileSystem/VirtualFileSystem.h>
+#include <Kernel/FileDescriptor.h>
+#include <Kernel/VirtualFileSystem.h>
 #include "ELFLoader.h"
 #include "MemoryManager.h"
 #include "i8253.h"
--- a/Kernel/Process.h
+++ b/Kernel/Process.h
@ -6,8 +6,8 @@
 #include "TTY.h"
 #include "Syscall.h"
 #include "GUITypes.h"
-#include <VirtualFileSystem/VirtualFileSystem.h>
-#include <VirtualFileSystem/UnixTypes.h>
+#include <Kernel/VirtualFileSystem.h>
+#include <Kernel/UnixTypes.h>
 #include <AK/InlineLinkedList.h>
 #include <AK/AKString.h>
 #include <AK/Vector.h>
--- a/Kernel/RandomDevice.cpp
+++ b/Kernel/RandomDevice.cpp
@ -0,0 +1,53 @@
+#include "RandomDevice.h"
+#include "Limits.h"
+#include <AK/StdLibExtras.h>
+
+RandomDevice::RandomDevice()
+    : CharacterDevice(1, 8)
+{
+}
+
+RandomDevice::~RandomDevice()
+{
+}
+
+// Simple rand() and srand() borrowed from the POSIX standard:
+
+static unsigned long next = 1;
+
+#define MY_RAND_MAX 32767
+static int myrand()
+{
+    next = next * 1103515245 + 12345;
+    return((unsigned)(next/((MY_RAND_MAX + 1) * 2)) % (MY_RAND_MAX + 1));
+}
+
+#if 0
+static void mysrand(unsigned seed)
+{
+    next = seed;
+}
+#endif
+
+bool RandomDevice::can_read(Process&) const
+{
+    return true;
+}
+
+ssize_t RandomDevice::read(Process&, byte* buffer, size_t bufferSize)
+{
+    const int range = 'z' - 'a';
+    ssize_t nread = min(bufferSize, GoodBufferSize);
+    for (ssize_t i = 0; i < nread; ++i) {
+        dword r = myrand() % range;
+        buffer[i] = 'a' + r;
+    }
+    return nread;
+}
+
+ssize_t RandomDevice::write(Process&, const byte*, size_t bufferSize)
+{
+    // FIXME: Use input for entropy? I guess that could be a neat feature?
+    return min(GoodBufferSize, bufferSize);
+}
+
--- a/Kernel/RandomDevice.h
+++ b/Kernel/RandomDevice.h
@ -0,0 +1,19 @@
+#pragma once
+
+#include "CharacterDevice.h"
+
+class RandomDevice final : public CharacterDevice {
+    AK_MAKE_ETERNAL
+public:
+    RandomDevice();
+    virtual ~RandomDevice() override;
+
+private:
+    // ^CharacterDevice
+    virtual ssize_t read(Process&, byte* buffer, size_t bufferSize) override;
+    virtual ssize_t write(Process&, const byte* buffer, size_t bufferSize) override;
+    virtual bool can_read(Process&) const override;
+    virtual bool can_write(Process&) const override { return true; }
+    virtual const char* class_name() const override { return "RandomDevice"; }
+};
+
--- a/Kernel/SyntheticFileSystem.cpp
+++ b/Kernel/SyntheticFileSystem.cpp
@ -0,0 +1,307 @@
+#include "SyntheticFileSystem.h"
+#include "FileDescriptor.h"
+#include <LibC/errno_numbers.h>
+#include <AK/StdLibExtras.h>
+
+#ifndef SERENITY
+typedef int InterruptDisabler;
+#define ASSERT_INTERRUPTS_DISABLED()
+#endif
+
+//#define SYNTHFS_DEBUG
+
+RetainPtr<SynthFS> SynthFS::create()
+{
+    return adopt(*new SynthFS);
+}
+
+SynthFS::SynthFS()
+{
+}
+
+SynthFS::~SynthFS()
+{
+}
+
+bool SynthFS::initialize()
+{
+    // Add a File for the root directory.
+    // FIXME: This needs work.
+    auto root = adopt(*new SynthFSInode(*this, RootInodeIndex));
+    root->m_parent = { id(), RootInodeIndex };
+    root->m_metadata.mode = 0040555;
+    root->m_metadata.uid = 0;
+    root->m_metadata.gid = 0;
+    root->m_metadata.size = 0;
+    root->m_metadata.mtime = mepoch;
+    m_inodes.set(RootInodeIndex, move(root));
+
+#ifndef SERENITY
+    addFile(createTextFile("file", String("I'm a synthetic file!\n").toByteBuffer(), 0100644));
+    addFile(createTextFile("message", String("Hey! This isn't my bottle!\n").toByteBuffer(), 0100644));
+    addFile(createGeneratedFile("lunk", [] { return String("/home/andreas/file1").toByteBuffer(); }, 00120777));
+#endif
+    return true;
+}
+
+RetainPtr<SynthFSInode> SynthFS::create_directory(String&& name)
+{
+    auto file = adopt(*new SynthFSInode(*this, generate_inode_index()));
+    file->m_name = move(name);
+    file->m_metadata.size = 0;
+    file->m_metadata.uid = 0;
+    file->m_metadata.gid = 0;
+    file->m_metadata.mode = 0040555;
+    file->m_metadata.mtime = mepoch;
+    return file;
+}
+
+RetainPtr<SynthFSInode> SynthFS::create_text_file(String&& name, ByteBuffer&& contents, Unix::mode_t mode)
+{
+    auto file = adopt(*new SynthFSInode(*this, generate_inode_index()));
+    file->m_data = contents;
+    file->m_name = move(name);
+    file->m_metadata.size = file->m_data.size();
+    file->m_metadata.uid = 100;
+    file->m_metadata.gid = 200;
+    file->m_metadata.mode = mode;
+    file->m_metadata.mtime = mepoch;
+    return file;
+}
+
+RetainPtr<SynthFSInode> SynthFS::create_generated_file(String&& name, Function<ByteBuffer(SynthFSInode&)>&& generator, Unix::mode_t mode)
+{
+    auto file = adopt(*new SynthFSInode(*this, generate_inode_index()));
+    file->m_generator = move(generator);
+    file->m_name = move(name);
+    file->m_metadata.size = 0;
+    file->m_metadata.uid = 0;
+    file->m_metadata.gid = 0;
+    file->m_metadata.mode = mode;
+    file->m_metadata.mtime = mepoch;
+    return file;
+}
+
+RetainPtr<SynthFSInode> SynthFS::create_generated_file(String&& name, Function<ByteBuffer(SynthFSInode&)>&& read_callback, Function<ssize_t(SynthFSInode&, const ByteBuffer&)>&& write_callback, Unix::mode_t mode)
+{
+    auto file = adopt(*new SynthFSInode(*this, generate_inode_index()));
+    file->m_generator = move(read_callback);
+    file->m_write_callback = move(write_callback);
+    file->m_name = move(name);
+    file->m_metadata.size = 0;
+    file->m_metadata.uid = 0;
+    file->m_metadata.gid = 0;
+    file->m_metadata.mode = mode;
+    file->m_metadata.mtime = mepoch;
+    return file;
+}
+
+InodeIdentifier SynthFS::add_file(RetainPtr<SynthFSInode>&& file, InodeIndex parent)
+{
+    ASSERT_INTERRUPTS_DISABLED();
+    ASSERT(file);
+    auto it = m_inodes.find(parent);
+    ASSERT(it != m_inodes.end());
+    auto new_inode_id = file->identifier();
+    file->m_metadata.inode = new_inode_id;
+    file->m_parent = { id(), parent };
+    (*it).value->m_children.append(file.ptr());
+    m_inodes.set(new_inode_id.index(), move(file));
+    return new_inode_id;
+}
+
+bool SynthFS::remove_file(InodeIndex inode)
+{
+    ASSERT_INTERRUPTS_DISABLED();
+    auto it = m_inodes.find(inode);
+    if (it == m_inodes.end())
+        return false;
+    auto& file = *(*it).value;
+
+    auto pit = m_inodes.find(file.m_parent.index());
+    if (pit == m_inodes.end())
+        return false;
+    auto& parent = *(*pit).value;
+    for (size_t i = 0; i < parent.m_children.size(); ++i) {
+        if (parent.m_children[i]->m_metadata.inode.index() != inode) {
+            continue;
+        }
+        parent.m_children.remove(i);
+        break;
+    }
+
+    Vector<InodeIndex> indices_to_remove;
+    indices_to_remove.ensure_capacity(file.m_children.size());
+    for (auto& child : file.m_children)
+        indices_to_remove.unchecked_append(child->m_metadata.inode.index());
+    for (auto& index : indices_to_remove)
+        remove_file(index);
+    m_inodes.remove(inode);
+    return true;
+}
+
+const char* SynthFS::class_name() const
+{
+    return "synthfs";
+}
+
+InodeIdentifier SynthFS::root_inode() const
+{
+    return { id(), 1 };
+}
+
+RetainPtr<Inode> SynthFS::create_inode(InodeIdentifier parentInode, const String& name, Unix::mode_t mode, unsigned size, int& error)
+{
+    (void) parentInode;
+    (void) name;
+    (void) mode;
+    (void) size;
+    (void) error;
+    kprintf("FIXME: Implement SyntheticFileSystem::create_inode().\n");
+    return { };
+}
+
+RetainPtr<Inode> SynthFS::create_directory(InodeIdentifier, const String&, Unix::mode_t, int& error)
+{
+    error = -EROFS;
+    return nullptr;
+}
+
+auto SynthFS::generate_inode_index() -> InodeIndex
+{
+    return m_next_inode_index++;
+}
+
+RetainPtr<Inode> SynthFSInode::parent() const
+{
+    return fs().get_inode(m_parent);
+}
+
+RetainPtr<Inode> SynthFS::get_inode(InodeIdentifier inode) const
+{
+    auto it = m_inodes.find(inode.index());
+    if (it == m_inodes.end())
+        return { };
+    return (*it).value;
+}
+
+SynthFSInode::SynthFSInode(SynthFS& fs, unsigned index)
+    : Inode(fs, index)
+{
+    m_metadata.inode = { fs.id(), index };
+}
+
+SynthFSInode::~SynthFSInode()
+{
+}
+
+InodeMetadata SynthFSInode::metadata() const
+{
+    return m_metadata;
+}
+
+ssize_t SynthFSInode::read_bytes(Unix::off_t offset, size_t count, byte* buffer, FileDescriptor* descriptor)
+{
+#ifdef SYNTHFS_DEBUG
+    kprintf("SynthFS: read_bytes %u\n", index());
+#endif
+    ASSERT(offset >= 0);
+    ASSERT(buffer);
+
+    ByteBuffer generatedData;
+    if (m_generator) {
+        if (!descriptor) {
+            generatedData = m_generator(*this);
+        } else {
+            if (!descriptor->generator_cache())
+                descriptor->generator_cache() = m_generator(*this);
+            generatedData = descriptor->generator_cache();
+        }
+    }
+
+    auto* data = generatedData ? &generatedData : &m_data;
+    ssize_t nread = min(static_cast<Unix::off_t>(data->size() - offset), static_cast<Unix::off_t>(count));
+    memcpy(buffer, data->pointer() + offset, nread);
+    if (nread == 0 && descriptor && descriptor->generator_cache())
+        descriptor->generator_cache().clear();
+    return nread;
+}
+
+bool SynthFSInode::traverse_as_directory(Function<bool(const FS::DirectoryEntry&)> callback)
+{
+    InterruptDisabler disabler;
+#ifdef SYNTHFS_DEBUG
+    kprintf("SynthFS: traverse_as_directory %u\n", index());
+#endif
+
+    if (!m_metadata.isDirectory())
+        return false;
+
+    callback({ ".", 1, m_metadata.inode, 2 });
+    callback({ "..", 2, m_parent, 2 });
+
+    for (auto& child : m_children)
+        callback({ child->m_name.characters(), child->m_name.length(), child->m_metadata.inode, child->m_metadata.isDirectory() ? (byte)2 : (byte)1 });
+    return true;
+}
+
+InodeIdentifier SynthFSInode::lookup(const String& name)
+{
+    ASSERT(is_directory());
+    if (name == ".")
+        return identifier();
+    if (name == "..")
+        return m_parent;
+    for (auto& child : m_children) {
+        if (child->m_name == name)
+            return child->identifier();
+    }
+    return { };
+}
+
+String SynthFSInode::reverse_lookup(InodeIdentifier child_id)
+{
+    ASSERT(is_directory());
+    for (auto& child : m_children) {
+        if (child->identifier() == child_id)
+            return child->m_name;
+    }
+    return { };
+}
+
+void SynthFSInode::flush_metadata()
+{
+}
+
+ssize_t SynthFSInode::write_bytes(Unix::off_t offset, size_t size, const byte* buffer, FileDescriptor*)
+{
+    if (!m_write_callback)
+        return -EPERM;
+    // FIXME: Being able to write into SynthFS at a non-zero offset seems like something we should support..
+    ASSERT(offset == 0);
+    bool success = m_write_callback(*this, ByteBuffer::wrap((byte*)buffer, size));
+    ASSERT(success);
+    return 0;
+}
+
+bool SynthFSInode::add_child(InodeIdentifier child_id, const String& name, byte file_type, int& error)
+{
+    (void) child_id;
+    (void) name;
+    (void) file_type;
+    (void) error;
+    ASSERT_NOT_REACHED();
+    return false;
+}
+
+bool SynthFSInode::remove_child(const String& name, int& error)
+{
+    (void) name;
+    (void) error;
+    ASSERT_NOT_REACHED();
+    return false;
+}
+
+SynthFSInodeCustomData::~SynthFSInodeCustomData()
+{
+}
--- a/Kernel/SyntheticFileSystem.h
+++ b/Kernel/SyntheticFileSystem.h
@ -0,0 +1,90 @@
+#pragma once
+
+#include "FileSystem.h"
+#include "UnixTypes.h"
+#include <AK/HashMap.h>
+
+class SynthFSInode;
+
+class SynthFS : public FS {
+public:
+    virtual ~SynthFS() override;
+    static RetainPtr<SynthFS> create();
+
+    virtual bool initialize() override;
+    virtual const char* class_name() const override;
+    virtual InodeIdentifier root_inode() const override;
+    virtual RetainPtr<Inode> create_inode(InodeIdentifier parentInode, const String& name, Unix::mode_t, unsigned size, int& error) override;
+    virtual RetainPtr<Inode> create_directory(InodeIdentifier parentInode, const String& name, Unix::mode_t, int& error) override;
+    virtual RetainPtr<Inode> get_inode(InodeIdentifier) const override;
+
+protected:
+    typedef unsigned InodeIndex;
+
+    InodeIndex generate_inode_index();
+    static constexpr InodeIndex RootInodeIndex = 1;
+
+    SynthFS();
+
+    RetainPtr<SynthFSInode> create_directory(String&& name);
+    RetainPtr<SynthFSInode> create_text_file(String&& name, ByteBuffer&&, Unix::mode_t = 0010644);
+    RetainPtr<SynthFSInode> create_generated_file(String&& name, Function<ByteBuffer(SynthFSInode&)>&&, Unix::mode_t = 0100644);
+    RetainPtr<SynthFSInode> create_generated_file(String&& name, Function<ByteBuffer(SynthFSInode&)>&&, Function<ssize_t(SynthFSInode&, const ByteBuffer&)>&&, Unix::mode_t = 0100644);
+
+    InodeIdentifier add_file(RetainPtr<SynthFSInode>&&, InodeIndex parent = RootInodeIndex);
+    bool remove_file(InodeIndex);
+
+private:
+    InodeIndex m_next_inode_index { 2 };
+    HashMap<InodeIndex, RetainPtr<SynthFSInode>> m_inodes;
+};
+
+struct SynthFSInodeCustomData {
+    virtual ~SynthFSInodeCustomData();
+};
+
+class SynthFSInode final : public Inode {
+    friend class SynthFS;
+public:
+    virtual ~SynthFSInode() override;
+
+    void set_custom_data(OwnPtr<SynthFSInodeCustomData>&& custom_data) { m_custom_data = move(custom_data); }
+    SynthFSInodeCustomData* custom_data() { return m_custom_data.ptr(); }
+    const SynthFSInodeCustomData* custom_data() const { return m_custom_data.ptr(); }
+
+private:
+    // ^Inode
+    virtual ssize_t read_bytes(Unix::off_t, size_t, byte* buffer, FileDescriptor*) override;
+    virtual InodeMetadata metadata() const override;
+    virtual bool traverse_as_directory(Function<bool(const FS::DirectoryEntry&)>) override;
+    virtual InodeIdentifier lookup(const String& name) override;
+    virtual String reverse_lookup(InodeIdentifier) override;
+    virtual void flush_metadata() override;
+    virtual ssize_t write_bytes(Unix::off_t, size_t, const byte* buffer, FileDescriptor*) override;
+    virtual bool add_child(InodeIdentifier child_id, const String& name, byte file_type, int& error) override;
+    virtual bool remove_child(const String& name, int& error) override;
+    virtual RetainPtr<Inode> parent() const override;
+
+    SynthFS& fs();
+    const SynthFS& fs() const;
+    SynthFSInode(SynthFS&, unsigned index);
+
+    String m_name;
+    InodeIdentifier m_parent;
+    ByteBuffer m_data;
+    Function<ByteBuffer(SynthFSInode&)> m_generator;
+    Function<ssize_t(SynthFSInode&, const ByteBuffer&)> m_write_callback;
+    Vector<SynthFSInode*> m_children;
+    InodeMetadata m_metadata;
+    OwnPtr<SynthFSInodeCustomData> m_custom_data;
+};
+
+inline SynthFS& SynthFSInode::fs()
+{
+    return static_cast<SynthFS&>(Inode::fs());
+}
+
+inline const SynthFS& SynthFSInode::fs() const
+{
+    return static_cast<const SynthFS&>(Inode::fs());
+}
--- a/Kernel/TTY.h
+++ b/Kernel/TTY.h
@ -1,8 +1,8 @@
 #pragma once

 #include "DoubleBuffer.h"
-#include <VirtualFileSystem/CharacterDevice.h>
-#include <VirtualFileSystem/UnixTypes.h>
+#include <Kernel/CharacterDevice.h>
+#include <Kernel/UnixTypes.h>

 class Process;

--- a/Kernel/UnixTypes.h
+++ b/Kernel/UnixTypes.h
@ -0,0 +1,302 @@
+#pragma once
+
+extern "C" {
+
+#define FD_SETSIZE 64
+struct fd_set { unsigned char bits[FD_SETSIZE / 8];  };
+
+namespace Unix {
+
+#define WNOHANG 1
+
+#define SIG_DFL ((void*)0)
+#define SIG_ERR ((void*)-1)
+#define SIG_IGN ((void*)1)
+
+#define SEEK_SET 0
+#define SEEK_CUR 1
+#define SEEK_END 2
+
+#define MAP_SHARED 0x01
+#define MAP_PRIVATE 0x02
+#define MAP_FIXED 0x10
+#define MAP_ANONYMOUS 0x20
+#define MAP_ANON MAP_ANONYMOUS
+
+#define PROT_READ 0x1
+#define PROT_WRITE 0x2
+#define PROT_EXEC 0x4
+#define PROT_NONE 0x0
+
+#define F_DUPFD 0
+#define F_GETFD 1
+#define F_SETFD 2
+#define F_GETFL 3
+#define F_SETFL 4
+
+#define FD_CLOEXEC 1
+
+/* c_cc characters */
+#define VINTR 0
+#define VQUIT 1
+#define VERASE 2
+#define VKILL 3
+#define VEOF 4
+#define VTIME 5
+#define VMIN 6
+#define VSWTC 7
+#define VSTART 8
+#define VSTOP 9
+#define VSUSP 10
+#define VEOL 11
+#define VREPRINT 12
+#define VDISCARD 13
+#define VWERASE 14
+#define VLNEXT 15
+#define VEOL2 16
+
+/* c_iflag bits */
+#define IGNBRK	0000001
+#define BRKINT	0000002
+#define IGNPAR	0000004
+#define PARMRK	0000010
+#define INPCK	0000020
+#define ISTRIP	0000040
+#define INLCR	0000100
+#define IGNCR	0000200
+#define ICRNL	0000400
+#define IUCLC	0001000
+#define IXON	0002000
+#define IXANY	0004000
+#define IXOFF	0010000
+#define IMAXBEL	0020000
+#define IUTF8	0040000
+
+/* c_oflag bits */
+#define OPOST	0000001
+#define OLCUC	0000002
+#define ONLCR	0000004
+#define OCRNL	0000010
+#define ONOCR	0000020
+#define ONLRET	0000040
+#define OFILL	0000100
+#define OFDEL	0000200
+#if defined __USE_MISC || defined __USE_XOPEN
+# define NLDLY	0000400
+# define   NL0	0000000
+# define   NL1	0000400
+# define CRDLY	0003000
+# define   CR0	0000000
+# define   CR1	0001000
+# define   CR2	0002000
+# define   CR3	0003000
+# define TABDLY	0014000
+# define   TAB0	0000000
+# define   TAB1	0004000
+# define   TAB2	0010000
+# define   TAB3	0014000
+# define BSDLY	0020000
+# define   BS0	0000000
+# define   BS1	0020000
+# define FFDLY	0100000
+# define   FF0	0000000
+# define   FF1	0100000
+#endif
+
+#define VTDLY	0040000
+#define   VT0	0000000
+#define   VT1	0040000
+
+#ifdef __USE_MISC
+# define XTABS	0014000
+#endif
+
+/* c_cflag bit meaning */
+#ifdef __USE_MISC
+# define CBAUD	0010017
+#endif
+#define  B0	0000000		/* hang up */
+#define  B50	0000001
+#define  B75	0000002
+#define  B110	0000003
+#define  B134	0000004
+#define  B150	0000005
+#define  B200	0000006
+#define  B300	0000007
+#define  B600	0000010
+#define  B1200	0000011
+#define  B1800	0000012
+#define  B2400	0000013
+#define  B4800	0000014
+#define  B9600	0000015
+#define  B19200	0000016
+#define  B38400	0000017
+#ifdef __USE_MISC
+# define EXTA B19200
+# define EXTB B38400
+#endif
+#define CSIZE	0000060
+#define   CS5	0000000
+#define   CS6	0000020
+#define   CS7	0000040
+#define   CS8	0000060
+#define CSTOPB	0000100
+#define CREAD	0000200
+#define PARENB	0000400
+#define PARODD	0001000
+#define HUPCL	0002000
+#define CLOCAL	0004000
+#ifdef __USE_MISC
+# define CBAUDEX 0010000
+#endif
+#define  B57600   0010001
+#define  B115200  0010002
+#define  B230400  0010003
+#define  B460800  0010004
+#define  B500000  0010005
+#define  B576000  0010006
+#define  B921600  0010007
+#define  B1000000 0010010
+#define  B1152000 0010011
+#define  B1500000 0010012
+#define  B2000000 0010013
+#define  B2500000 0010014
+#define  B3000000 0010015
+#define  B3500000 0010016
+#define  B4000000 0010017
+#define __MAX_BAUD B4000000
+#ifdef __USE_MISC
+# define CIBAUD	  002003600000		/* input baud rate (not used) */
+# define CMSPAR   010000000000		/* mark or space (stick) parity */
+# define CRTSCTS  020000000000		/* flow control */
+#endif
+
+/* c_lflag bits */
+#define ISIG	0000001
+#define ICANON	0000002
+#if defined __USE_MISC || (defined __USE_XOPEN && !defined __USE_XOPEN2K)
+# define XCASE	0000004
+#endif
+#define ECHO	0000010
+#define ECHOE	0000020
+#define ECHOK	0000040
+#define ECHONL	0000100
+#define NOFLSH	0000200
+#define TOSTOP	0000400
+#ifdef __USE_MISC
+# define ECHOCTL 0001000
+# define ECHOPRT 0002000
+# define ECHOKE	 0004000
+# define FLUSHO	 0010000
+# define PENDIN	 0040000
+#endif
+#define IEXTEN	0100000
+#ifdef __USE_MISC
+# define EXTPROC 0200000
+#endif
+
+/* tcflow() and TCXONC use these */
+#define	TCOOFF		0
+#define	TCOON		1
+#define	TCIOFF		2
+#define	TCION		3
+
+/* tcflush() and TCFLSH use these */
+#define	TCIFLUSH	0
+#define	TCOFLUSH	1
+#define	TCIOFLUSH	2
+
+/* tcsetattr uses these */
+#define	TCSANOW		0
+#define	TCSADRAIN	1
+#define	TCSAFLUSH	2
+
+struct winsize {
+    unsigned short ws_row;
+    unsigned short ws_col;
+};
+
+typedef dword dev_t;
+typedef dword ino_t;
+typedef dword mode_t;
+typedef dword nlink_t;
+typedef dword uid_t;
+typedef dword gid_t;
+typedef dword clock_t;
+
+struct tms {
+    clock_t tms_utime;
+    clock_t tms_stime;
+    clock_t tms_cutime;
+    clock_t tms_cstime;
+};
+
+typedef void (*__sighandler_t)(int);
+typedef __sighandler_t sighandler_t;
+
+typedef dword sigset_t;
+typedef void siginfo_t;
+
+struct sigaction {
+    union {
+        void (*sa_handler)(int);
+        void (*sa_sigaction)(int, siginfo_t*, void*);
+    };
+    sigset_t sa_mask;
+    int sa_flags;
+    void (*sa_restorer)(void);
+};
+
+#define SA_NOCLDSTOP 1
+#define SA_NOCLDWAIT 2
+#define SA_SIGINFO 4
+
+#define SIG_BLOCK 0
+#define SIG_UNBLOCK 1
+#define SIG_SETMASK 2
+
+// FIXME: Support 64-bit offsets!
+typedef signed_dword off_t;
+typedef unsigned int time_t;
+
+struct utimbuf {
+    time_t actime;
+    time_t modtime;
+};
+
+typedef dword blksize_t;
+typedef dword blkcnt_t;
+
+#define NCCS 32
+
+typedef uint32_t tcflag_t;
+typedef uint8_t cc_t;
+
+struct termios {
+    tcflag_t c_iflag;
+    tcflag_t c_oflag;
+    tcflag_t c_cflag;
+    tcflag_t c_lflag;
+    cc_t     c_cc[NCCS];
+};
+
+struct stat {
+    dev_t     st_dev;     /* ID of device containing file */
+    ino_t     st_ino;     /* inode number */
+    mode_t    st_mode;    /* protection */
+    nlink_t   st_nlink;   /* number of hard links */
+    uid_t     st_uid;     /* user ID of owner */
+    gid_t     st_gid;     /* group ID of owner */
+    dev_t     st_rdev;    /* device ID (if special file) */
+    off_t     st_size;    /* total size, in bytes */
+    blksize_t st_blksize; /* blocksize for file system I/O */
+    blkcnt_t  st_blocks;  /* number of 512B blocks allocated */
+    time_t    st_atime;   /* time of last access */
+    time_t    st_mtime;   /* time of last modification */
+    time_t    st_ctime;   /* time of last status change */
+};
+
+}
+
+}
+
--- a/Kernel/VirtualFileSystem.cpp
+++ b/Kernel/VirtualFileSystem.cpp
@ -0,0 +1,425 @@
+#include "VirtualFileSystem.h"
+#include "FileDescriptor.h"
+#include "FileSystem.h"
+#include <AK/FileSystemPath.h>
+#include <AK/StringBuilder.h>
+#include <AK/kmalloc.h>
+#include <AK/kstdio.h>
+#include <AK/ktime.h>
+#include "CharacterDevice.h"
+#include <LibC/errno_numbers.h>
+
+//#define VFS_DEBUG
+
+static VFS* s_the;
+
+VFS& VFS::the()
+{
+    ASSERT(s_the);
+    return *s_the;
+}
+
+void VFS::initialize_globals()
+{
+    s_the = nullptr;
+    FS::initialize_globals();
+}
+
+VFS::VFS()
+{
+#ifdef VFS_DEBUG
+    kprintf("VFS: Constructing VFS\n");
+#endif
+    s_the = this;
+}
+
+VFS::~VFS()
+{
+}
+
+InodeIdentifier VFS::root_inode_id() const
+{
+    ASSERT(m_root_inode);
+    return m_root_inode->identifier();
+}
+
+bool VFS::mount(RetainPtr<FS>&& fileSystem, const String& path)
+{
+    ASSERT(fileSystem);
+    int error;
+    auto inode = resolve_path(path, root_inode_id(), error);
+    if (!inode.is_valid()) {
+        kprintf("VFS: mount can't resolve mount point '%s'\n", path.characters());
+        return false;
+    }
+
+    kprintf("VFS: mounting %s{%p} at %s (inode: %u)\n", fileSystem->class_name(), fileSystem.ptr(), path.characters(), inode.index());
+    // FIXME: check that this is not already a mount point
+    auto mount = make<Mount>(inode, move(fileSystem));
+    m_mounts.append(move(mount));
+    return true;
+}
+
+bool VFS::mount_root(RetainPtr<FS>&& fileSystem)
+{
+    if (m_root_inode) {
+        kprintf("VFS: mount_root can't mount another root\n");
+        return false;
+    }
+
+    auto mount = make<Mount>(InodeIdentifier(), move(fileSystem));
+
+    auto root_inode_id = mount->guest().fs()->root_inode();
+    auto root_inode = mount->guest().fs()->get_inode(root_inode_id);
+    if (!root_inode->is_directory()) {
+        kprintf("VFS: root inode (%02u:%08u) for / is not a directory :(\n", root_inode_id.fsid(), root_inode_id.index());
+        return false;
+    }
+
+    m_root_inode = move(root_inode);
+
+    kprintf("VFS: mounted root on %s{%p}\n",
+        m_root_inode->fs().class_name(),
+        &m_root_inode->fs());
+
+    m_mounts.append(move(mount));
+    return true;
+}
+
+auto VFS::find_mount_for_host(InodeIdentifier inode) -> Mount*
+{
+    for (auto& mount : m_mounts) {
+        if (mount->host() == inode)
+            return mount.ptr();
+    }
+    return nullptr;
+}
+
+auto VFS::find_mount_for_guest(InodeIdentifier inode) -> Mount*
+{
+    for (auto& mount : m_mounts) {
+        if (mount->guest() == inode)
+            return mount.ptr();
+    }
+    return nullptr;
+}
+
+bool VFS::is_vfs_root(InodeIdentifier inode) const
+{
+    return inode == root_inode_id();
+}
+
+void VFS::traverse_directory_inode(Inode& dir_inode, Function<bool(const FS::DirectoryEntry&)> callback)
+{
+    dir_inode.traverse_as_directory([&] (const FS::DirectoryEntry& entry) {
+        InodeIdentifier resolvedInode;
+        if (auto mount = find_mount_for_host(entry.inode))
+            resolvedInode = mount->guest();
+        else
+            resolvedInode = entry.inode;
+
+        if (dir_inode.identifier().is_root_inode() && !is_vfs_root(dir_inode.identifier()) && !strcmp(entry.name, "..")) {
+            auto mount = find_mount_for_guest(entry.inode);
+            ASSERT(mount);
+            resolvedInode = mount->host();
+        }
+        callback(FS::DirectoryEntry(entry.name, entry.name_length, resolvedInode, entry.fileType));
+        return true;
+    });
+}
+
+RetainPtr<FileDescriptor> VFS::open(RetainPtr<CharacterDevice>&& device, int& error, int options)
+{
+    // FIXME: Respect options.
+    (void) options;
+    (void) error;
+    return FileDescriptor::create(move(device));
+}
+
+RetainPtr<FileDescriptor> VFS::open(const String& path, int& error, int options, mode_t mode, InodeIdentifier base)
+{
+    auto inode_id = resolve_path(path, base, error, options);
+    auto inode = get_inode(inode_id);
+    if (!inode) {
+        if (options & O_CREAT)
+            return create(path, error, options, mode, base);
+        return nullptr;
+    }
+    auto metadata = inode->metadata();
+    if (metadata.isCharacterDevice()) {
+        auto it = m_character_devices.find(encodedDevice(metadata.majorDevice, metadata.minorDevice));
+        if (it == m_character_devices.end()) {
+            kprintf("VFS::open: no such character device %u,%u\n", metadata.majorDevice, metadata.minorDevice);
+            return nullptr;
+        }
+        return (*it).value->open(error, options);
+    }
+    return FileDescriptor::create(move(inode));
+}
+
+RetainPtr<FileDescriptor> VFS::create(const String& path, int& error, int options, mode_t mode, InodeIdentifier base)
+{
+    (void) options;
+    error = -EWHYTHO;
+
+    if (!isSocket(mode) && !isFIFO(mode) && !isBlockDevice(mode) && !isCharacterDevice(mode)) {
+        // Turn it into a regular file. (This feels rather hackish.)
+        mode |= 0100000;
+    }
+
+    // FIXME: This won't work nicely across mount boundaries.
+    FileSystemPath p(path);
+    if (!p.is_valid()) {
+        error = -EINVAL;
+        return nullptr;
+    }
+
+    InodeIdentifier parent_dir;
+    auto existing_file = resolve_path(path, base, error, 0, &parent_dir);
+    if (existing_file.is_valid()) {
+        error = -EEXIST;
+        return nullptr;
+    }
+    if (!parent_dir.is_valid()) {
+        error = -ENOENT;
+        return nullptr;
+    }
+    if (error != -ENOENT) {
+        return nullptr;
+    }
+    dbgprintf("VFS::create_file: '%s' in %u:%u\n", p.basename().characters(), parent_dir.fsid(), parent_dir.index());
+    auto new_file = parent_dir.fs()->create_inode(parent_dir, p.basename(), mode, 0, error);
+    if (!new_file)
+        return nullptr;
+
+    error = 0;
+    return FileDescriptor::create(move(new_file));
+}
+
+bool VFS::mkdir(const String& path, mode_t mode, InodeIdentifier base, int& error)
+{
+    error = -EWHYTHO;
+    // FIXME: This won't work nicely across mount boundaries.
+    FileSystemPath p(path);
+    if (!p.is_valid()) {
+        error = -EINVAL;
+        return false;
+    }
+
+    InodeIdentifier parent_dir;
+    auto existing_dir = resolve_path(path, base, error, 0, &parent_dir);
+    if (existing_dir.is_valid()) {
+        error = -EEXIST;
+        return false;
+    }
+    if (!parent_dir.is_valid()) {
+        error = -ENOENT;
+        return false;
+    }
+    if (error != -ENOENT) {
+        return false;
+    }
+    dbgprintf("VFS::mkdir: '%s' in %u:%u\n", p.basename().characters(), parent_dir.fsid(), parent_dir.index());
+    auto new_dir = base.fs()->create_directory(parent_dir, p.basename(), mode, error);
+    if (new_dir) {
+        error = 0;
+        return true;
+    }
+    return false;
+}
+
+bool VFS::unlink(const String& path, Inode& base, int& error)
+{
+    error = -EWHYTHO;
+    // FIXME: This won't work nicely across mount boundaries.
+    FileSystemPath p(path);
+    if (!p.is_valid()) {
+        error = -EINVAL;
+        return false;
+    }
+
+    InodeIdentifier parent_dir;
+    auto inode_id = resolve_path(path, base.identifier(), error, 0, &parent_dir);
+    if (!inode_id.is_valid()) {
+        error = -ENOENT;
+        return false;
+    }
+
+    auto parent_inode = get_inode(parent_dir);
+    // FIXME: The reverse_lookup here can definitely be avoided.
+    if (!parent_inode->remove_child(parent_inode->reverse_lookup(inode_id), error))
+        return false;
+
+    error = 0;
+    return true;
+}
+
+InodeIdentifier VFS::resolve_symbolic_link(InodeIdentifier base, Inode& symlink_inode, int& error)
+{
+    auto symlink_contents = symlink_inode.read_entire();
+    if (!symlink_contents)
+        return { };
+    auto linkee = String((const char*)symlink_contents.pointer(), symlink_contents.size());
+#ifdef VFS_DEBUG
+    kprintf("linkee (%s)(%u) from %u:%u\n", linkee.characters(), linkee.length(), base.fsid(), base.index());
+#endif
+    return resolve_path(linkee, base, error);
+}
+
+RetainPtr<Inode> VFS::get_inode(InodeIdentifier inode_id)
+{
+    if (!inode_id.is_valid())
+        return nullptr;
+    return inode_id.fs()->get_inode(inode_id);
+}
+
+String VFS::absolute_path(Inode& core_inode)
+{
+    int error;
+    Vector<InodeIdentifier> lineage;
+    RetainPtr<Inode> inode = &core_inode;
+    while (inode->identifier() != root_inode_id()) {
+        if (auto* mount = find_mount_for_guest(inode->identifier()))
+            lineage.append(mount->host());
+        else
+            lineage.append(inode->identifier());
+
+        InodeIdentifier parent_id;
+        if (inode->is_directory()) {
+            parent_id = resolve_path("..", inode->identifier(), error);
+        } else {
+            parent_id = inode->parent()->identifier();
+        }
+        ASSERT(parent_id.is_valid());
+        inode = get_inode(parent_id);
+    }
+    if (lineage.is_empty())
+        return "/";
+    lineage.append(root_inode_id());
+    StringBuilder builder;
+    for (size_t i = lineage.size() - 1; i >= 1; --i) {
+        auto& child = lineage[i - 1];
+        auto parent = lineage[i];
+        if (auto* mount = find_mount_for_host(parent))
+            parent = mount->guest();
+        builder.append('/');
+        auto parent_inode = get_inode(parent);
+        builder.append(parent_inode->reverse_lookup(child));
+    }
+    return builder.build();
+}
+
+InodeIdentifier VFS::resolve_path(const String& path, InodeIdentifier base, int& error, int options, InodeIdentifier* deepest_dir)
+{
+    if (path.is_empty()) {
+        error = -EINVAL;
+        return { };
+    }
+
+    auto parts = path.split('/');
+    InodeIdentifier crumb_id;
+
+    if (path[0] == '/')
+        crumb_id = root_inode_id();
+    else
+        crumb_id = base.is_valid() ? base : root_inode_id();
+
+    if (deepest_dir)
+        *deepest_dir = crumb_id;
+
+    for (unsigned i = 0; i < parts.size(); ++i) {
+        bool inode_was_root_at_head_of_loop = crumb_id.is_root_inode();
+        auto& part = parts[i];
+        if (part.is_empty())
+            break;
+        auto crumb_inode = get_inode(crumb_id);
+        if (!crumb_inode) {
+#ifdef VFS_DEBUG
+            kprintf("invalid metadata\n");
+#endif
+            error = -EIO;
+            return { };
+        }
+        auto metadata = crumb_inode->metadata();
+        if (!metadata.isDirectory()) {
+#ifdef VFS_DEBUG
+            kprintf("parent of <%s> not directory, it's inode %u:%u / %u:%u, mode: %u, size: %u\n", part.characters(), inode.fsid(), inode.index(), metadata.inode.fsid(), metadata.inode.index(), metadata.mode, metadata.size);
+#endif
+            error = -ENOTDIR;
+            return { };
+        }
+        auto parent = crumb_id;
+        crumb_id = crumb_inode->lookup(part);
+        if (!crumb_id.is_valid()) {
+#ifdef VFS_DEBUG
+            kprintf("child <%s>(%u) not found in directory, %02u:%08u\n", part.characters(), part.length(), parent.fsid(), parent.index());
+#endif
+            error = -ENOENT;
+            return { };
+        }
+#ifdef VFS_DEBUG
+        kprintf("<%s> %u:%u\n", part.characters(), inode.fsid(), inode.index());
+#endif
+        if (auto mount = find_mount_for_host(crumb_id)) {
+#ifdef VFS_DEBUG
+            kprintf("  -- is host\n");
+#endif
+            crumb_id = mount->guest();
+        }
+        if (inode_was_root_at_head_of_loop && crumb_id.is_root_inode() && !is_vfs_root(crumb_id) && part == "..") {
+#ifdef VFS_DEBUG
+            kprintf("  -- is guest\n");
+#endif
+            auto mount = find_mount_for_guest(crumb_id);
+            auto dir_inode = get_inode(mount->host());
+            crumb_id = dir_inode->lookup("..");
+        }
+        crumb_inode = get_inode(crumb_id);
+        metadata = crumb_inode->metadata();
+        if (metadata.isDirectory()) {
+            if (deepest_dir)
+                *deepest_dir = crumb_id;
+        }
+        if (metadata.isSymbolicLink()) {
+            if (i == parts.size() - 1) {
+                if (options & O_NOFOLLOW) {
+                    error = -ELOOP;
+                    return { };
+                }
+                if (options & O_NOFOLLOW_NOERROR)
+                    return crumb_id;
+            }
+            crumb_id = resolve_symbolic_link(parent, *crumb_inode, error);
+            if (!crumb_id.is_valid()) {
+                kprintf("Symbolic link resolution failed :(\n");
+                return { };
+            }
+        }
+    }
+
+    return crumb_id;
+}
+
+VFS::Mount::Mount(InodeIdentifier host, RetainPtr<FS>&& guest_fs)
+    : m_host(host)
+    , m_guest(guest_fs->root_inode())
+    , m_guest_fs(move(guest_fs))
+{
+}
+
+void VFS::register_character_device(CharacterDevice& device)
+{
+    m_character_devices.set(encodedDevice(device.major(), device.minor()), &device);
+}
+
+void VFS::for_each_mount(Function<void(const Mount&)> callback) const
+{
+    for (auto& mount : m_mounts) {
+        callback(*mount);
+    }
+}
+
+void VFS::sync()
+{
+    FS::sync();
+}
--- a/Kernel/VirtualFileSystem.h
+++ b/Kernel/VirtualFileSystem.h
@ -0,0 +1,103 @@
+#pragma once
+
+#include <AK/HashMap.h>
+#include <AK/OwnPtr.h>
+#include <AK/RetainPtr.h>
+#include <AK/AKString.h>
+#include <AK/Vector.h>
+#include <AK/Function.h>
+#include "InodeIdentifier.h"
+#include "InodeMetadata.h"
+#include "Limits.h"
+#include "FileSystem.h"
+
+#define O_RDONLY 0
+#define O_WRONLY 1
+#define O_RDWR 2
+#define O_CREAT 0100
+#define O_EXCL 0200
+#define O_NOCTTY 0400
+#define O_TRUNC 01000
+#define O_APPEND 02000
+#define O_NONBLOCK 04000
+#define O_DIRECTORY 00200000
+#define O_NOFOLLOW 00400000
+#define O_CLOEXEC 02000000
+#define O_NOFOLLOW_NOERROR 0x4000000
+
+class CharacterDevice;
+class FileDescriptor;
+
+inline constexpr dword encodedDevice(unsigned major, unsigned minor)
+{
+    return (minor & 0xff) | (major << 8) | ((minor & ~0xff) << 12);
+}
+
+class VFS;
+
+class VFS {
+    AK_MAKE_ETERNAL
+public:
+    static void initialize_globals();
+
+    class Mount {
+    public:
+        Mount(InodeIdentifier host, RetainPtr<FS>&&);
+
+        InodeIdentifier host() const { return m_host; }
+        InodeIdentifier guest() const { return m_guest; }
+
+        const FS& guest_fs() const { return *m_guest_fs; }
+
+    private:
+        InodeIdentifier m_host;
+        InodeIdentifier m_guest;
+        RetainPtr<FS> m_guest_fs;
+    };
+
+    static VFS& the() PURE;
+
+    VFS();
+    ~VFS();
+
+    bool mount_root(RetainPtr<FS>&&);
+    bool mount(RetainPtr<FS>&&, const String& path);
+
+    RetainPtr<FileDescriptor> open(RetainPtr<CharacterDevice>&&, int& error, int options);
+    RetainPtr<FileDescriptor> open(const String& path, int& error, int options, mode_t mode, InodeIdentifier base = InodeIdentifier());
+    RetainPtr<FileDescriptor> create(const String& path, int& error, int options, mode_t mode, InodeIdentifier base);
+    bool mkdir(const String& path, mode_t mode, InodeIdentifier base, int& error);
+    bool unlink(const String& path, Inode& base, int& error);
+
+    void register_character_device(CharacterDevice&);
+
+    size_t mount_count() const { return m_mounts.size(); }
+    void for_each_mount(Function<void(const Mount&)>) const;
+
+    String absolute_path(Inode&);
+
+    InodeIdentifier root_inode_id() const;
+    Inode* root_inode() { return m_root_inode.ptr(); }
+    const Inode* root_inode() const { return m_root_inode.ptr(); }
+
+    void sync();
+
+private:
+    friend class FileDescriptor;
+
+    RetainPtr<Inode> get_inode(InodeIdentifier);
+
+    bool is_vfs_root(InodeIdentifier) const;
+
+    void traverse_directory_inode(Inode&, Function<bool(const FS::DirectoryEntry&)>);
+    InodeIdentifier resolve_path(const String& path, InodeIdentifier base, int& error, int options = 0, InodeIdentifier* deepest_dir = nullptr);
+    InodeIdentifier resolve_symbolic_link(InodeIdentifier base, Inode& symlink_inode, int& error);
+
+    Mount* find_mount_for_host(InodeIdentifier);
+    Mount* find_mount_for_guest(InodeIdentifier);
+
+    RetainPtr<Inode> m_root_inode;
+    Vector<OwnPtr<Mount>> m_mounts;
+    HashMap<dword, CharacterDevice*> m_character_devices;
+};
+
--- a/Kernel/ZeroDevice.cpp
+++ b/Kernel/ZeroDevice.cpp
@ -0,0 +1,31 @@
+#include "ZeroDevice.h"
+#include "Limits.h"
+#include <AK/StdLibExtras.h>
+#include <AK/kstdio.h>
+
+ZeroDevice::ZeroDevice()
+    : CharacterDevice(1, 5)
+{
+}
+
+ZeroDevice::~ZeroDevice()
+{
+}
+
+bool ZeroDevice::can_read(Process&) const
+{
+    return true;
+}
+
+ssize_t ZeroDevice::read(Process&, byte* buffer, size_t bufferSize)
+{
+    size_t count = min(GoodBufferSize, bufferSize);
+    memset(buffer, 0, count);
+    return count;
+}
+
+ssize_t ZeroDevice::write(Process&, const byte*, size_t bufferSize)
+{
+    return min(GoodBufferSize, bufferSize);
+}
+
--- a/Kernel/ZeroDevice.h
+++ b/Kernel/ZeroDevice.h
@ -0,0 +1,19 @@
+#pragma once
+
+#include "CharacterDevice.h"
+
+class ZeroDevice final : public CharacterDevice {
+    AK_MAKE_ETERNAL
+public:
+    ZeroDevice();
+    virtual ~ZeroDevice() override;
+
+private:
+    // ^CharacterDevice
+    virtual ssize_t read(Process&, byte* buffer, size_t bufferSize) override;
+    virtual ssize_t write(Process&, const byte* buffer, size_t bufferSize) override;
+    virtual bool can_read(Process&) const override;
+    virtual bool can_write(Process&) const override { return true; }
+    virtual const char* class_name() const override { return "ZeroDevice"; }
+};
+
--- a/Kernel/ext2_fs.h
+++ b/Kernel/ext2_fs.h
@ -0,0 +1,750 @@
+/*
+ *  linux/include/linux/ext2_fs.h
+ *
+ * Copyright (C) 1992, 1993, 1994, 1995
+ * Remy Card (card@masi.ibp.fr)
+ * Laboratoire MASI - Institut Blaise Pascal
+ * Universite Pierre et Marie Curie (Paris VI)
+ *
+ *  from
+ *
+ *  linux/include/linux/minix_fs.h
+ *
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ */
+
+#ifndef _LINUX_EXT2_FS_H
+#define _LINUX_EXT2_FS_H
+
+#include "ext2_types.h"		/* Changed from linux/types.h */
+
+/*
+ * The second extended filesystem constants/structures
+ */
+
+/*
+ * Define EXT2FS_DEBUG to produce debug messages
+ */
+#undef EXT2FS_DEBUG
+
+/*
+ * Define EXT2_PREALLOCATE to preallocate data blocks for expanding files
+ */
+#define EXT2_PREALLOCATE
+#define EXT2_DEFAULT_PREALLOC_BLOCKS	8
+
+/*
+ * The second extended file system version
+ */
+#define EXT2FS_DATE		"95/08/09"
+#define EXT2FS_VERSION		"0.5b"
+
+/*
+ * Special inode numbers
+ */
+#define EXT2_BAD_INO		 1	/* Bad blocks inode */
+#define EXT2_ROOT_INO		 2	/* Root inode */
+#define EXT2_ACL_IDX_INO	 3	/* ACL inode */
+#define EXT2_ACL_DATA_INO	 4	/* ACL inode */
+#define EXT2_BOOT_LOADER_INO	 5	/* Boot loader inode */
+#define EXT2_UNDEL_DIR_INO	 6	/* Undelete directory inode */
+#define EXT2_RESIZE_INO		 7	/* Reserved group descriptors inode */
+#define EXT2_JOURNAL_INO	 8	/* Journal inode */
+
+/* First non-reserved inode for old ext2 filesystems */
+#define EXT2_GOOD_OLD_FIRST_INO	11
+
+/*
+ * The second extended file system magic number
+ */
+#define EXT2_SUPER_MAGIC	0xEF53
+
+#ifdef __KERNEL__
+#define EXT2_SB(sb)	(&((sb)->u.ext2_sb))
+#else
+/* Assume that user mode programs are passing in an ext2fs superblock, not
+ * a kernel struct super_block.  This will allow us to call the feature-test
+ * macros from user land. */
+#define EXT2_SB(sb)	(sb)
+#endif
+
+/*
+ * Maximal count of links to a file
+ */
+#define EXT2_LINK_MAX		65000
+
+/*
+ * Macro-instructions used to manage several block sizes
+ */
+#define EXT2_MIN_BLOCK_LOG_SIZE		10	/* 1024 */
+#define EXT2_MAX_BLOCK_LOG_SIZE		16	/* 65536 */
+#define EXT2_MIN_BLOCK_SIZE	(1 << EXT2_MIN_BLOCK_LOG_SIZE)
+#define EXT2_MAX_BLOCK_SIZE	(1 << EXT2_MAX_BLOCK_LOG_SIZE)
+#ifdef __KERNEL__
+#define EXT2_BLOCK_SIZE(s)	((s)->s_blocksize)
+#define EXT2_BLOCK_SIZE_BITS(s)	((s)->s_blocksize_bits)
+#define EXT2_ADDR_PER_BLOCK_BITS(s)	(EXT2_SB(s)->addr_per_block_bits)
+#define EXT2_INODE_SIZE(s)	(EXT2_SB(s)->s_inode_size)
+#define EXT2_FIRST_INO(s)	(EXT2_SB(s)->s_first_ino)
+#else
+#define EXT2_BLOCK_SIZE(s)	(EXT2_MIN_BLOCK_SIZE << (s)->s_log_block_size)
+#define EXT2_BLOCK_SIZE_BITS(s)	((s)->s_log_block_size + 10)
+#define EXT2_INODE_SIZE(s)	(((s)->s_rev_level == EXT2_GOOD_OLD_REV) ? \
+				 EXT2_GOOD_OLD_INODE_SIZE : (s)->s_inode_size)
+#define EXT2_FIRST_INO(s)	(((s)->s_rev_level == EXT2_GOOD_OLD_REV) ? \
+				 EXT2_GOOD_OLD_FIRST_INO : (s)->s_first_ino)
+#endif
+#define EXT2_ADDR_PER_BLOCK(s)	(EXT2_BLOCK_SIZE(s) / sizeof(__u32))
+
+/*
+ * Macro-instructions used to manage fragments
+ */
+#define EXT2_MIN_FRAG_SIZE		EXT2_MIN_BLOCK_SIZE
+#define EXT2_MAX_FRAG_SIZE		EXT2_MAX_BLOCK_SIZE
+#define EXT2_MIN_FRAG_LOG_SIZE		EXT2_MIN_BLOCK_LOG_SIZE
+#ifdef __KERNEL__
+# define EXT2_FRAG_SIZE(s)		(EXT2_SB(s)->s_frag_size)
+# define EXT2_FRAGS_PER_BLOCK(s)	(EXT2_SB(s)->s_frags_per_block)
+#else
+# define EXT2_FRAG_SIZE(s)		(EXT2_MIN_FRAG_SIZE << (s)->s_log_frag_size)
+# define EXT2_FRAGS_PER_BLOCK(s)	(EXT2_BLOCK_SIZE(s) / EXT2_FRAG_SIZE(s))
+#endif
+
+/*
+ * ACL structures
+ */
+struct ext2_acl_header	/* Header of Access Control Lists */
+{
+	__u32	aclh_size;
+	__u32	aclh_file_count;
+	__u32	aclh_acle_count;
+	__u32	aclh_first_acle;
+};
+
+struct ext2_acl_entry	/* Access Control List Entry */
+{
+	__u32	acle_size;
+	__u16	acle_perms;	/* Access permissions */
+	__u16	acle_type;	/* Type of entry */
+	__u16	acle_tag;	/* User or group identity */
+	__u16	acle_pad1;
+	__u32	acle_next;	/* Pointer on next entry for the */
+					/* same inode or on next free entry */
+};
+
+/*
+ * Structure of a blocks group descriptor
+ */
+struct ext2_group_desc
+{
+	__u32	bg_block_bitmap;	/* Blocks bitmap block */
+	__u32	bg_inode_bitmap;	/* Inodes bitmap block */
+	__u32	bg_inode_table;		/* Inodes table block */
+	__u16	bg_free_blocks_count;	/* Free blocks count */
+	__u16	bg_free_inodes_count;	/* Free inodes count */
+	__u16	bg_used_dirs_count;	/* Directories count */
+	__u16	bg_flags;
+	__u32	bg_reserved[2];
+	__u16	bg_itable_unused;	/* Unused inodes count */
+	__u16	bg_checksum;		/* crc16(s_uuid+grouo_num+group_desc)*/
+};
+
+struct ext4_group_desc
+{
+	__u32	bg_block_bitmap;	/* Blocks bitmap block */
+	__u32	bg_inode_bitmap;	/* Inodes bitmap block */
+	__u32	bg_inode_table;		/* Inodes table block */
+	__u16	bg_free_blocks_count;	/* Free blocks count */
+	__u16	bg_free_inodes_count;	/* Free inodes count */
+	__u16	bg_used_dirs_count;	/* Directories count */
+	__u16	bg_flags;
+	__u32	bg_reserved[2];
+	__u16	bg_itable_unused;	/* Unused inodes count */
+	__u16	bg_checksum;		/* crc16(s_uuid+grouo_num+group_desc)*/
+	__u32	bg_block_bitmap_hi;	/* Blocks bitmap block MSB */
+	__u32	bg_inode_bitmap_hi;	/* Inodes bitmap block MSB */
+	__u32	bg_inode_table_hi;	/* Inodes table block MSB */
+	__u16	bg_free_blocks_count_hi;/* Free blocks count MSB */
+	__u16	bg_free_inodes_count_hi;/* Free inodes count MSB */
+	__u16	bg_used_dirs_count_hi;	/* Directories count MSB */
+	__u16   bg_pad;
+	__u32	bg_reserved2[3];
+};
+
+#define EXT2_BG_INODE_UNINIT	0x0001 /* Inode table/bitmap not initialized */
+#define EXT2_BG_BLOCK_UNINIT	0x0002 /* Block bitmap not initialized */
+#define EXT2_BG_INODE_ZEROED	0x0004 /* On-disk itable initialized to zero */
+
+/*
+ * Data structures used by the directory indexing feature
+ *
+ * Note: all of the multibyte integer fields are little endian.
+ */
+
+/*
+ * Note: dx_root_info is laid out so that if it should somehow get
+ * overlaid by a dirent the two low bits of the hash version will be
+ * zero.  Therefore, the hash version mod 4 should never be 0.
+ * Sincerely, the paranoia department.
+ */
+struct ext2_dx_root_info {
+	__u32 reserved_zero;
+	__u8 hash_version; /* 0 now, 1 at release */
+	__u8 info_length; /* 8 */
+	__u8 indirect_levels;
+	__u8 unused_flags;
+};
+
+#define EXT2_HASH_LEGACY		0
+#define EXT2_HASH_HALF_MD4		1
+#define EXT2_HASH_TEA			2
+#define EXT2_HASH_LEGACY_UNSIGNED	3 /* reserved for userspace lib */
+#define EXT2_HASH_HALF_MD4_UNSIGNED	4 /* reserved for userspace lib */
+#define EXT2_HASH_TEA_UNSIGNED		5 /* reserved for userspace lib */
+
+#define EXT2_HASH_FLAG_INCOMPAT	0x1
+
+struct ext2_dx_entry {
+	__u32 hash;
+	__u32 block;
+};
+
+struct ext2_dx_countlimit {
+	__u16 limit;
+	__u16 count;
+};
+
+
+/*
+ * Macro-instructions used to manage group descriptors
+ */
+#define EXT2_MIN_DESC_SIZE             32
+#define EXT2_MIN_DESC_SIZE_64BIT       64
+#define EXT2_MAX_DESC_SIZE             EXT2_MIN_BLOCK_SIZE
+#define EXT2_DESC_SIZE(s)                                                \
+       ((EXT2_SB(s)->s_feature_incompat & EXT4_FEATURE_INCOMPAT_64BIT) ? \
+	(s)->s_desc_size : EXT2_MIN_DESC_SIZE)
+
+#define EXT2_BLOCKS_PER_GROUP(s)	(EXT2_SB(s)->s_blocks_per_group)
+#define EXT2_INODES_PER_GROUP(s)	(EXT2_SB(s)->s_inodes_per_group)
+#define EXT2_INODES_PER_BLOCK(s)	(EXT2_BLOCK_SIZE(s)/EXT2_INODE_SIZE(s))
+/* limits imposed by 16-bit value gd_free_{blocks,inode}_count */
+#define EXT2_MAX_BLOCKS_PER_GROUP(s)	((1 << 16) - 8)
+#define EXT2_MAX_INODES_PER_GROUP(s)	((1 << 16) - EXT2_INODES_PER_BLOCK(s))
+#ifdef __KERNEL__
+#define EXT2_DESC_PER_BLOCK(s)		(EXT2_SB(s)->s_desc_per_block)
+#define EXT2_DESC_PER_BLOCK_BITS(s)	(EXT2_SB(s)->s_desc_per_block_bits)
+#else
+#define EXT2_DESC_PER_BLOCK(s)		(EXT2_BLOCK_SIZE(s) / EXT2_DESC_SIZE(s))
+#endif
+
+/*
+ * Constants relative to the data blocks
+ */
+#define EXT2_NDIR_BLOCKS		12
+#define EXT2_IND_BLOCK			EXT2_NDIR_BLOCKS
+#define EXT2_DIND_BLOCK			(EXT2_IND_BLOCK + 1)
+#define EXT2_TIND_BLOCK			(EXT2_DIND_BLOCK + 1)
+#define EXT2_N_BLOCKS			(EXT2_TIND_BLOCK + 1)
+
+/*
+ * Inode flags
+ */
+#define EXT2_SECRM_FL			0x00000001 /* Secure deletion */
+#define EXT2_UNRM_FL			0x00000002 /* Undelete */
+#define EXT2_COMPR_FL			0x00000004 /* Compress file */
+#define EXT2_SYNC_FL			0x00000008 /* Synchronous updates */
+#define EXT2_IMMUTABLE_FL		0x00000010 /* Immutable file */
+#define EXT2_APPEND_FL			0x00000020 /* writes to file may only append */
+#define EXT2_NODUMP_FL			0x00000040 /* do not dump file */
+#define EXT2_NOATIME_FL			0x00000080 /* do not update atime */
+/* Reserved for compression usage... */
+#define EXT2_DIRTY_FL			0x00000100
+#define EXT2_COMPRBLK_FL		0x00000200 /* One or more compressed clusters */
+#define EXT2_NOCOMPR_FL			0x00000400 /* Access raw compressed data */
+#define EXT2_ECOMPR_FL			0x00000800 /* Compression error */
+/* End compression flags --- maybe not all used */
+#define EXT2_BTREE_FL			0x00001000 /* btree format dir */
+#define EXT2_INDEX_FL			0x00001000 /* hash-indexed directory */
+#define EXT2_IMAGIC_FL			0x00002000
+#define EXT3_JOURNAL_DATA_FL		0x00004000 /* file data should be journaled */
+#define EXT2_NOTAIL_FL			0x00008000 /* file tail should not be merged */
+#define EXT2_DIRSYNC_FL 		0x00010000 /* Synchronous directory modifications */
+#define EXT2_TOPDIR_FL			0x00020000 /* Top of directory hierarchies*/
+#define EXT4_HUGE_FILE_FL               0x00040000 /* Set to each huge file */
+#define EXT4_EXTENTS_FL 		0x00080000 /* Inode uses extents */
+#define EXT2_RESERVED_FL		0x80000000 /* reserved for ext2 lib */
+
+#define EXT2_FL_USER_VISIBLE		0x000BDFFF /* User visible flags */
+#define EXT2_FL_USER_MODIFIABLE		0x000080FF /* User modifiable flags */
+
+/*
+ * ioctl commands
+ */
+
+/* Used for online resize */
+struct ext2_new_group_input {
+	__u32 group;		/* Group number for this data */
+	__u32 block_bitmap;	/* Absolute block number of block bitmap */
+	__u32 inode_bitmap;	/* Absolute block number of inode bitmap */
+	__u32 inode_table;	/* Absolute block number of inode table start */
+	__u32 blocks_count;	/* Total number of blocks in this group */
+	__u16 reserved_blocks;	/* Number of reserved blocks in this group */
+	__u16 unused;		/* Number of reserved GDT blocks in group */
+};
+
+struct ext4_new_group_input {
+	__u32 group;		/* Group number for this data */
+	__u64 block_bitmap;	/* Absolute block number of block bitmap */
+	__u64 inode_bitmap;	/* Absolute block number of inode bitmap */
+	__u64 inode_table;	/* Absolute block number of inode table start */
+	__u32 blocks_count;	/* Total number of blocks in this group */
+	__u16 reserved_blocks;	/* Number of reserved blocks in this group */
+	__u16 unused;
+};
+
+#ifdef __GNU__			/* Needed for the Hurd */
+#define _IOT_ext2_new_group_input _IOT (_IOTS(__u32), 5, _IOTS(__u16), 2, 0, 0)
+#endif
+
+#define EXT2_IOC_GETFLAGS		_IOR('f', 1, long)
+#define EXT2_IOC_SETFLAGS		_IOW('f', 2, long)
+#define EXT2_IOC_GETVERSION		_IOR('v', 1, long)
+#define EXT2_IOC_SETVERSION		_IOW('v', 2, long)
+#define EXT2_IOC_GETVERSION_NEW		_IOR('f', 3, long)
+#define EXT2_IOC_SETVERSION_NEW		_IOW('f', 4, long)
+#define EXT2_IOC_GROUP_EXTEND		_IOW('f', 7, unsigned long)
+#define EXT2_IOC_GROUP_ADD		_IOW('f', 8,struct ext2_new_group_input)
+#define EXT4_IOC_GROUP_ADD		_IOW('f', 8,struct ext4_new_group_input)
+
+/*
+ * Structure of an inode on the disk
+ */
+struct ext2_inode {
+	__u16	i_mode;		/* File mode */
+	__u16	i_uid;		/* Low 16 bits of Owner Uid */
+	__u32	i_size;		/* Size in bytes */
+	__u32	i_atime;	/* Access time */
+	__u32	i_ctime;	/* Inode change time */
+	__u32	i_mtime;	/* Modification time */
+	__u32	i_dtime;	/* Deletion Time */
+	__u16	i_gid;		/* Low 16 bits of Group Id */
+	__u16	i_links_count;	/* Links count */
+	__u32	i_blocks;	/* Blocks count */
+	__u32	i_flags;	/* File flags */
+	union {
+		struct {
+			__u32	l_i_version; /* was l_i_reserved1 */
+		} linux1;
+		struct {
+			__u32  h_i_translator;
+		} hurd1;
+	} osd1;				/* OS dependent 1 */
+	__u32	i_block[EXT2_N_BLOCKS];/* Pointers to blocks */
+	__u32	i_generation;	/* File version (for NFS) */
+	__u32	i_file_acl;	/* File ACL */
+	__u32	i_dir_acl;	/* Directory ACL */
+	__u32	i_faddr;	/* Fragment address */
+	union {
+		struct {
+			__u16	l_i_blocks_hi;
+			__u16	l_i_file_acl_high;
+			__u16	l_i_uid_high;	/* these 2 fields    */
+			__u16	l_i_gid_high;	/* were reserved2[0] */
+			__u32	l_i_reserved2;
+		} linux2;
+		struct {
+			__u8	h_i_frag;	/* Fragment number */
+			__u8	h_i_fsize;	/* Fragment size */
+			__u16	h_i_mode_high;
+			__u16	h_i_uid_high;
+			__u16	h_i_gid_high;
+			__u32	h_i_author;
+		} hurd2;
+	} osd2;				/* OS dependent 2 */
+};
+
+/*
+ * Permanent part of an large inode on the disk
+ */
+struct ext2_inode_large {
+	__u16	i_mode;		/* File mode */
+	__u16	i_uid;		/* Low 16 bits of Owner Uid */
+	__u32	i_size;		/* Size in bytes */
+	__u32	i_atime;	/* Access time */
+	__u32	i_ctime;	/* Inode Change time */
+	__u32	i_mtime;	/* Modification time */
+	__u32	i_dtime;	/* Deletion Time */
+	__u16	i_gid;		/* Low 16 bits of Group Id */
+	__u16	i_links_count;	/* Links count */
+	__u32	i_blocks;	/* Blocks count */
+	__u32	i_flags;	/* File flags */
+	union {
+		struct {
+			__u32	l_i_version; /* was l_i_reserved1 */
+		} linux1;
+		struct {
+			__u32  h_i_translator;
+		} hurd1;
+	} osd1;				/* OS dependent 1 */
+	__u32	i_block[EXT2_N_BLOCKS];/* Pointers to blocks */
+	__u32	i_generation;	/* File version (for NFS) */
+	__u32	i_file_acl;	/* File ACL */
+	__u32	i_dir_acl;	/* Directory ACL */
+	__u32	i_faddr;	/* Fragment address */
+	union {
+		struct {
+			__u16	l_i_blocks_hi;
+			__u16	l_i_file_acl_high;
+			__u16	l_i_uid_high;	/* these 2 fields    */
+			__u16	l_i_gid_high;	/* were reserved2[0] */
+			__u32	l_i_reserved2;
+		} linux2;
+		struct {
+			__u8	h_i_frag;	/* Fragment number */
+			__u8	h_i_fsize;	/* Fragment size */
+			__u16	h_i_mode_high;
+			__u16	h_i_uid_high;
+			__u16	h_i_gid_high;
+			__u32	h_i_author;
+		} hurd2;
+	} osd2;				/* OS dependent 2 */
+	__u16	i_extra_isize;
+	__u16	i_pad1;
+	__u32	i_ctime_extra;	/* extra Change time (nsec << 2 | epoch) */
+	__u32	i_mtime_extra;	/* extra Modification time (nsec << 2 | epoch) */
+	__u32	i_atime_extra;	/* extra Access time (nsec << 2 | epoch) */
+	__u32	i_crtime;	/* File creation time */
+	__u32	i_crtime_extra;	/* extra File creation time (nsec << 2 | epoch)*/
+	__u32	i_version_hi;	/* high 32 bits for 64-bit version */
+};
+
+#define i_size_high	i_dir_acl
+
+#if defined(__KERNEL__) || defined(__linux__)
+#define i_reserved1	osd1.linux1.l_i_reserved1
+#define i_frag		osd2.linux2.l_i_frag
+#define i_fsize		osd2.linux2.l_i_fsize
+#define i_uid_low	i_uid
+#define i_gid_low	i_gid
+#define i_uid_high	osd2.linux2.l_i_uid_high
+#define i_gid_high	osd2.linux2.l_i_gid_high
+#define i_reserved2	osd2.linux2.l_i_reserved2
+#else
+#if defined(__GNU__)
+
+#define i_translator	osd1.hurd1.h_i_translator
+#define i_frag		osd2.hurd2.h_i_frag;
+#define i_fsize		osd2.hurd2.h_i_fsize;
+#define i_uid_high	osd2.hurd2.h_i_uid_high
+#define i_gid_high	osd2.hurd2.h_i_gid_high
+#define i_author	osd2.hurd2.h_i_author
+
+#endif  /* __GNU__ */
+#endif	/* defined(__KERNEL__) || defined(__linux__) */
+
+#define inode_uid(inode)	((inode).i_uid | (inode).osd2.linux2.l_i_uid_high << 16)
+#define inode_gid(inode)	((inode).i_gid | (inode).osd2.linux2.l_i_gid_high << 16)
+#define ext2fs_set_i_uid_high(inode,x) ((inode).osd2.linux2.l_i_uid_high = (x))
+#define ext2fs_set_i_gid_high(inode,x) ((inode).osd2.linux2.l_i_gid_high = (x))
+
+/*
+ * File system states
+ */
+#define EXT2_VALID_FS			0x0001	/* Unmounted cleanly */
+#define EXT2_ERROR_FS			0x0002	/* Errors detected */
+#define EXT3_ORPHAN_FS			0x0004	/* Orphans being recovered */
+
+/*
+ * Misc. filesystem flags
+ */
+#define EXT2_FLAGS_SIGNED_HASH		0x0001  /* Signed dirhash in use */
+#define EXT2_FLAGS_UNSIGNED_HASH	0x0002  /* Unsigned dirhash in use */
+#define EXT2_FLAGS_TEST_FILESYS		0x0004	/* OK for use on development code */
+
+/*
+ * Mount flags
+ */
+#define EXT2_MOUNT_CHECK		0x0001	/* Do mount-time checks */
+#define EXT2_MOUNT_GRPID		0x0004	/* Create files with directory's group */
+#define EXT2_MOUNT_DEBUG		0x0008	/* Some debugging messages */
+#define EXT2_MOUNT_ERRORS_CONT		0x0010	/* Continue on errors */
+#define EXT2_MOUNT_ERRORS_RO		0x0020	/* Remount fs ro on errors */
+#define EXT2_MOUNT_ERRORS_PANIC		0x0040	/* Panic on errors */
+#define EXT2_MOUNT_MINIX_DF		0x0080	/* Mimics the Minix statfs */
+#define EXT2_MOUNT_NO_UID32		0x0200  /* Disable 32-bit UIDs */
+
+#define clear_opt(o, opt)		o &= ~EXT2_MOUNT_##opt
+#define set_opt(o, opt)			o |= EXT2_MOUNT_##opt
+#define test_opt(sb, opt)		(EXT2_SB(sb)->s_mount_opt & \
+					 EXT2_MOUNT_##opt)
+/*
+ * Maximal mount counts between two filesystem checks
+ */
+#define EXT2_DFL_MAX_MNT_COUNT		20	/* Allow 20 mounts */
+#define EXT2_DFL_CHECKINTERVAL		0	/* Don't use interval check */
+
+/*
+ * Behaviour when detecting errors
+ */
+#define EXT2_ERRORS_CONTINUE		1	/* Continue execution */
+#define EXT2_ERRORS_RO			2	/* Remount fs read-only */
+#define EXT2_ERRORS_PANIC		3	/* Panic */
+#define EXT2_ERRORS_DEFAULT		EXT2_ERRORS_CONTINUE
+
+/*
+ * Structure of the super block
+ */
+struct ext2_super_block {
+	__u32	s_inodes_count;		/* Inodes count */
+	__u32	s_blocks_count;		/* Blocks count */
+	__u32	s_r_blocks_count;	/* Reserved blocks count */
+	__u32	s_free_blocks_count;	/* Free blocks count */
+	__u32	s_free_inodes_count;	/* Free inodes count */
+	__u32	s_first_data_block;	/* First Data Block */
+	__u32	s_log_block_size;	/* Block size */
+	__s32	s_log_frag_size;	/* Fragment size */
+	__u32	s_blocks_per_group;	/* # Blocks per group */
+	__u32	s_frags_per_group;	/* # Fragments per group */
+	__u32	s_inodes_per_group;	/* # Inodes per group */
+	__u32	s_mtime;		/* Mount time */
+	__u32	s_wtime;		/* Write time */
+	__u16	s_mnt_count;		/* Mount count */
+	__s16	s_max_mnt_count;	/* Maximal mount count */
+	__u16	s_magic;		/* Magic signature */
+	__u16	s_state;		/* File system state */
+	__u16	s_errors;		/* Behaviour when detecting errors */
+	__u16	s_minor_rev_level;	/* minor revision level */
+	__u32	s_lastcheck;		/* time of last check */
+	__u32	s_checkinterval;	/* max. time between checks */
+	__u32	s_creator_os;		/* OS */
+	__u32	s_rev_level;		/* Revision level */
+	__u16	s_def_resuid;		/* Default uid for reserved blocks */
+	__u16	s_def_resgid;		/* Default gid for reserved blocks */
+	/*
+	 * These fields are for EXT2_DYNAMIC_REV superblocks only.
+	 *
+	 * Note: the difference between the compatible feature set and
+	 * the incompatible feature set is that if there is a bit set
+	 * in the incompatible feature set that the kernel doesn't
+	 * know about, it should refuse to mount the filesystem.
+	 *
+	 * e2fsck's requirements are more strict; if it doesn't know
+	 * about a feature in either the compatible or incompatible
+	 * feature set, it must abort and not try to meddle with
+	 * things it doesn't understand...
+	 */
+	__u32	s_first_ino;		/* First non-reserved inode */
+	__u16   s_inode_size;		/* size of inode structure */
+	__u16	s_block_group_nr;	/* block group # of this superblock */
+	__u32	s_feature_compat;	/* compatible feature set */
+	__u32	s_feature_incompat;	/* incompatible feature set */
+	__u32	s_feature_ro_compat;	/* readonly-compatible feature set */
+	__u8	s_uuid[16];		/* 128-bit uuid for volume */
+	char	s_volume_name[16];	/* volume name */
+	char	s_last_mounted[64];	/* directory where last mounted */
+	__u32	s_algorithm_usage_bitmap; /* For compression */
+	/*
+	 * Performance hints.  Directory preallocation should only
+	 * happen if the EXT2_FEATURE_COMPAT_DIR_PREALLOC flag is on.
+	 */
+	__u8	s_prealloc_blocks;	/* Nr of blocks to try to preallocate*/
+	__u8	s_prealloc_dir_blocks;	/* Nr to preallocate for dirs */
+	__u16	s_reserved_gdt_blocks;	/* Per group table for online growth */
+	/*
+	 * Journaling support valid if EXT2_FEATURE_COMPAT_HAS_JOURNAL set.
+	 */
+	__u8	s_journal_uuid[16];	/* uuid of journal superblock */
+	__u32	s_journal_inum;		/* inode number of journal file */
+	__u32	s_journal_dev;		/* device number of journal file */
+	__u32	s_last_orphan;		/* start of list of inodes to delete */
+	__u32	s_hash_seed[4];		/* HTREE hash seed */
+	__u8	s_def_hash_version;	/* Default hash version to use */
+	__u8	s_jnl_backup_type; 	/* Default type of journal backup */
+	__u16	s_desc_size;		/* Group desc. size: INCOMPAT_64BIT */
+	__u32	s_default_mount_opts;
+	__u32	s_first_meta_bg;	/* First metablock group */
+	__u32	s_mkfs_time;		/* When the filesystem was created */
+	__u32	s_jnl_blocks[17]; 	/* Backup of the journal inode */
+	__u32	s_blocks_count_hi;	/* Blocks count high 32bits */
+	__u32	s_r_blocks_count_hi;	/* Reserved blocks count high 32 bits*/
+	__u32	s_free_blocks_hi; 	/* Free blocks count */
+	__u16	s_min_extra_isize;	/* All inodes have at least # bytes */
+	__u16	s_want_extra_isize; 	/* New inodes should reserve # bytes */
+	__u32	s_flags;		/* Miscellaneous flags */
+	__u16   s_raid_stride;		/* RAID stride */
+	__u16   s_mmp_interval;         /* # seconds to wait in MMP checking */
+	__u64   s_mmp_block;            /* Block for multi-mount protection */
+	__u32   s_raid_stripe_width;    /* blocks on all data disks (N*stride)*/
+	__u8	s_log_groups_per_flex;	/* FLEX_BG group size */
+	__u8    s_reserved_char_pad;
+	__u16	s_reserved_pad;		/* Padding to next 32bits */
+	__u32   s_reserved[162];        /* Padding to the end of the block */
+};
+
+/*
+ * Codes for operating systems
+ */
+#define EXT2_OS_LINUX		0
+#define EXT2_OS_HURD		1
+#define EXT2_OBSO_OS_MASIX	2
+#define EXT2_OS_FREEBSD		3
+#define EXT2_OS_LITES		4
+
+/*
+ * Revision levels
+ */
+#define EXT2_GOOD_OLD_REV	0	/* The good old (original) format */
+#define EXT2_DYNAMIC_REV	1	/* V2 format w/ dynamic inode sizes */
+
+#define EXT2_CURRENT_REV	EXT2_GOOD_OLD_REV
+#define EXT2_MAX_SUPP_REV	EXT2_DYNAMIC_REV
+
+#define EXT2_GOOD_OLD_INODE_SIZE 128
+
+/*
+ * Journal inode backup types
+ */
+#define EXT3_JNL_BACKUP_BLOCKS	1
+
+/*
+ * Feature set definitions
+ */
+
+#define EXT2_HAS_COMPAT_FEATURE(sb,mask)			\
+	( EXT2_SB(sb)->s_feature_compat & (mask) )
+#define EXT2_HAS_RO_COMPAT_FEATURE(sb,mask)			\
+	( EXT2_SB(sb)->s_feature_ro_compat & (mask) )
+#define EXT2_HAS_INCOMPAT_FEATURE(sb,mask)			\
+	( EXT2_SB(sb)->s_feature_incompat & (mask) )
+
+#define EXT2_FEATURE_COMPAT_DIR_PREALLOC	0x0001
+#define EXT2_FEATURE_COMPAT_IMAGIC_INODES	0x0002
+#define EXT3_FEATURE_COMPAT_HAS_JOURNAL		0x0004
+#define EXT2_FEATURE_COMPAT_EXT_ATTR		0x0008
+#define EXT2_FEATURE_COMPAT_RESIZE_INODE	0x0010
+#define EXT2_FEATURE_COMPAT_DIR_INDEX		0x0020
+#define EXT2_FEATURE_COMPAT_LAZY_BG		0x0040
+
+#define EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER	0x0001
+#define EXT2_FEATURE_RO_COMPAT_LARGE_FILE	0x0002
+/* #define EXT2_FEATURE_RO_COMPAT_BTREE_DIR	0x0004 not used */
+#define EXT4_FEATURE_RO_COMPAT_HUGE_FILE	0x0008
+#define EXT4_FEATURE_RO_COMPAT_GDT_CSUM		0x0010
+#define EXT4_FEATURE_RO_COMPAT_DIR_NLINK	0x0020
+#define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE	0x0040
+
+#define EXT2_FEATURE_INCOMPAT_COMPRESSION	0x0001
+#define EXT2_FEATURE_INCOMPAT_FILETYPE		0x0002
+#define EXT3_FEATURE_INCOMPAT_RECOVER		0x0004 /* Needs recovery */
+#define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV	0x0008 /* Journal device */
+#define EXT2_FEATURE_INCOMPAT_META_BG		0x0010
+#define EXT3_FEATURE_INCOMPAT_EXTENTS		0x0040
+#define EXT4_FEATURE_INCOMPAT_64BIT		0x0080
+#define EXT4_FEATURE_INCOMPAT_MMP		0x0100
+#define EXT4_FEATURE_INCOMPAT_FLEX_BG		0x0200
+
+
+#define EXT2_FEATURE_COMPAT_SUPP	0
+#define EXT2_FEATURE_INCOMPAT_SUPP	(EXT2_FEATURE_INCOMPAT_FILETYPE)
+#define EXT2_FEATURE_RO_COMPAT_SUPP	(EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER| \
+					 EXT2_FEATURE_RO_COMPAT_LARGE_FILE| \
+					 EXT4_FEATURE_RO_COMPAT_DIR_NLINK| \
+					 EXT2_FEATURE_RO_COMPAT_BTREE_DIR)
+
+/*
+ * Default values for user and/or group using reserved blocks
+ */
+#define EXT2_DEF_RESUID		0
+#define EXT2_DEF_RESGID		0
+
+/*
+ * Default mount options
+ */
+#define EXT2_DEFM_DEBUG		0x0001
+#define EXT2_DEFM_BSDGROUPS	0x0002
+#define EXT2_DEFM_XATTR_USER	0x0004
+#define EXT2_DEFM_ACL		0x0008
+#define EXT2_DEFM_UID16		0x0010
+#define EXT3_DEFM_JMODE		0x0060
+#define EXT3_DEFM_JMODE_DATA	0x0020
+#define EXT3_DEFM_JMODE_ORDERED	0x0040
+#define EXT3_DEFM_JMODE_WBACK	0x0060
+
+/*
+ * Structure of a directory entry
+ */
+#define EXT2_NAME_LEN 255
+
+struct ext2_dir_entry {
+	__u32	inode;			/* Inode number */
+	__u16	rec_len;		/* Directory entry length */
+	__u16	name_len;		/* Name length */
+	char	name[EXT2_NAME_LEN];	/* File name */
+};
+
+/*
+ * The new version of the directory entry.  Since EXT2 structures are
+ * stored in intel byte order, and the name_len field could never be
+ * bigger than 255 chars, it's safe to reclaim the extra byte for the
+ * file_type field.
+ */
+struct ext2_dir_entry_2 {
+	__u32	inode;			/* Inode number */
+	__u16	rec_len;		/* Directory entry length */
+	__u8	name_len;		/* Name length */
+	__u8	file_type;
+	char	name[EXT2_NAME_LEN];	/* File name */
+};
+
+/*
+ * Ext2 directory file types.  Only the low 3 bits are used.  The
+ * other bits are reserved for now.
+ */
+#define EXT2_FT_UNKNOWN		0
+#define EXT2_FT_REG_FILE	1
+#define EXT2_FT_DIR		2
+#define EXT2_FT_CHRDEV		3
+#define EXT2_FT_BLKDEV		4
+#define EXT2_FT_FIFO		5
+#define EXT2_FT_SOCK		6
+#define EXT2_FT_SYMLINK		7
+
+#define EXT2_FT_MAX		8
+
+/*
+ * EXT2_DIR_PAD defines the directory entries boundaries
+ *
+ * NOTE: It must be a multiple of 4
+ */
+#define EXT2_DIR_PAD			4
+#define EXT2_DIR_ROUND			(EXT2_DIR_PAD - 1)
+#define EXT2_DIR_REC_LEN(name_len)	(((name_len) + 8 + EXT2_DIR_ROUND) & \
+					 ~EXT2_DIR_ROUND)
+
+/*
+ * This structure will be used for multiple mount protection. It will be
+ * written into the block number saved in the s_mmp_block field in the
+ * superblock.
+ */
+#define	EXT2_MMP_MAGIC    0x004D4D50 /* ASCII for MMP */
+#define	EXT2_MMP_CLEAN    0xFF4D4D50 /* Value of mmp_seq for clean unmount */
+#define	EXT2_MMP_FSCK_ON  0xE24D4D50 /* Value of mmp_seq when being fscked */
+
+struct mmp_struct {
+	__u32	mmp_magic;
+	__u32	mmp_seq;
+	__u64	mmp_time;
+	char	mmp_nodename[64];
+	char	mmp_bdevname[32];
+	__u16	mmp_interval;
+	__u16	mmp_pad1;
+	__u32	mmp_pad2;
+};
+
+/*
+ * Interval in number of seconds to update the MMP sequence number.
+ */
+#define EXT2_MMP_DEF_INTERVAL	5
+
+#endif	/* _LINUX_EXT2_FS_H */
--- a/Kernel/ext2_types.h
+++ b/Kernel/ext2_types.h
@ -0,0 +1,145 @@
+/* 
+ * If linux/types.h is already been included, assume it has defined
+ * everything we need.  (cross fingers)  Other header files may have 
+ * also defined the types that we need.
+ */
+#if (!defined(_LINUX_TYPES_H) && !defined(_BLKID_TYPES_H) && \
+	!defined(_EXT2_TYPES_H))
+#define _EXT2_TYPES_H
+
+#define __S8_TYPEDEF __signed__ char
+#define __U8_TYPEDEF unsigned char
+#define __S16_TYPEDEF __signed__ short
+#define __U16_TYPEDEF unsigned short
+#define __S32_TYPEDEF __signed__ int
+#define __U32_TYPEDEF unsigned int
+#define __S64_TYPEDEF __signed__ long long
+#define __U64_TYPEDEF unsigned long long
+
+#ifdef __U8_TYPEDEF
+typedef __U8_TYPEDEF __u8;
+#else
+typedef unsigned char __u8;
+#endif
+
+#ifdef __S8_TYPEDEF
+typedef __S8_TYPEDEF __s8;
+#else
+typedef signed char __s8;
+#endif
+
+#ifdef __U16_TYPEDEF
+typedef __U16_TYPEDEF __u16;
+#else
+#if (4 == 2)
+typedef	unsigned int	__u16;
+#else
+#if (2 == 2)
+typedef	unsigned short	__u16;
+#else
+  ?==error: undefined 16 bit type
+#endif /* SIZEOF_SHORT == 2 */
+#endif /* SIZEOF_INT == 2 */
+#endif /* __U16_TYPEDEF */
+
+#ifdef __S16_TYPEDEF
+typedef __S16_TYPEDEF __s16;
+#else
+#if (4 == 2)
+typedef	int		__s16;
+#else
+#if (2 == 2)
+typedef	short		__s16;
+#else
+  ?==error: undefined 16 bit type
+#endif /* SIZEOF_SHORT == 2 */
+#endif /* SIZEOF_INT == 2 */
+#endif /* __S16_TYPEDEF */
+
+
+#ifdef __U32_TYPEDEF
+typedef __U32_TYPEDEF __u32;
+#else
+#if (4 == 4)
+typedef	unsigned int	__u32;
+#else
+#if (4 == 4)
+typedef	unsigned long	__u32;
+#else
+#if (2 == 4)
+typedef	unsigned short	__u32;
+#else
+ ?== error: undefined 32 bit type
+#endif /* SIZEOF_SHORT == 4 */
+#endif /* SIZEOF_LONG == 4 */
+#endif /* SIZEOF_INT == 4 */
+#endif /* __U32_TYPEDEF */
+
+#ifdef __S32_TYPEDEF
+typedef __S32_TYPEDEF __s32;
+#else
+#if (4 == 4)
+typedef	int		__s32;
+#else
+#if (4 == 4)
+typedef	long		__s32;
+#else
+#if (2 == 4)
+typedef	short		__s32;
+#else
+ ?== error: undefined 32 bit type
+#endif /* SIZEOF_SHORT == 4 */
+#endif /* SIZEOF_LONG == 4 */
+#endif /* SIZEOF_INT == 4 */
+#endif /* __S32_TYPEDEF */
+
+#ifdef __U64_TYPEDEF
+typedef __U64_TYPEDEF __u64;
+#else
+#if (4 == 8)
+typedef unsigned int	__u64;
+#else
+#if (4 == 8)
+typedef unsigned long	__u64;
+#else
+#if (8 == 8)
+typedef unsigned long long	__u64;
+#endif /* SIZEOF_LONG_LONG == 8 */
+#endif /* SIZEOF_LONG == 8 */
+#endif /* SIZEOF_INT == 8 */
+#endif /* __U64_TYPEDEF */
+
+#ifdef __S64_TYPEDEF
+typedef __S64_TYPEDEF __s64;
+#else
+#if (4 == 8)
+typedef int		__s64;
+#else
+#if (4 == 8)
+typedef long		__s64;
+#else
+#if (8 == 8)
+#if defined(__GNUC__)
+typedef __signed__ long long 	__s64;
+#else
+typedef signed long long 	__s64;
+#endif /* __GNUC__ */
+#endif /* SIZEOF_LONG_LONG == 8 */
+#endif /* SIZEOF_LONG == 8 */
+#endif /* SIZEOF_INT == 8 */
+#endif /* __S64_TYPEDEF */
+
+#undef __S8_TYPEDEF
+#undef __U8_TYPEDEF
+#undef __S16_TYPEDEF
+#undef __U16_TYPEDEF
+#undef __S32_TYPEDEF
+#undef __U32_TYPEDEF
+#undef __S64_TYPEDEF
+#undef __U64_TYPEDEF
+
+#endif /* _*_TYPES_H */
+
+/* These defines are needed for the public ext2fs.h header file */
+#define HAVE_SYS_TYPES_H 1
+#undef WORDS_BIGENDIAN
--- a/Kernel/init.cpp
+++ b/Kernel/init.cpp
@ -9,12 +9,12 @@
 #include "CMOS.h"
 #include "IDEDiskDevice.h"
 #include "KSyms.h"
-#include <VirtualFileSystem/NullDevice.h>
-#include <VirtualFileSystem/ZeroDevice.h>
-#include <VirtualFileSystem/FullDevice.h>
-#include <VirtualFileSystem/RandomDevice.h>
-#include <VirtualFileSystem/Ext2FileSystem.h>
-#include <VirtualFileSystem/VirtualFileSystem.h>
+#include <Kernel/NullDevice.h>
+#include <Kernel/ZeroDevice.h>
+#include <Kernel/FullDevice.h>
+#include <Kernel/RandomDevice.h>
+#include <Kernel/Ext2FileSystem.h>
+#include <Kernel/VirtualFileSystem.h>
 #include "GUIEventDevice.h"
 #include "MemoryManager.h"
 #include "ProcFileSystem.h"