Kernel: Split the Ext2FileSystem.{cpp,h} files into smaller components

11 files changed, 840 insertions, 797 deletions

diff --git a/Kernel/Arch/x86/init.cpp b/Kernel/Arch/x86/init.cpp
index fb165e9d34..070d5da303 100644
--- a/Kernel/Arch/x86/init.cpp
+++ b/Kernel/Arch/x86/init.cpp
@@ -29,7 +29,6 @@
 #include <Kernel/Devices/SelfTTYDevice.h>
 #include <Kernel/Devices/SerialDevice.h>
 #include <Kernel/Devices/ZeroDevice.h>
-#include <Kernel/FileSystem/Ext2FileSystem.h>
 #include <Kernel/FileSystem/SysFS/Registry.h>
 #include <Kernel/FileSystem/SysFS/Subsystems/Firmware/Directory.h>
 #include <Kernel/FileSystem/VirtualFileSystem.h>
diff --git a/Kernel/CMakeLists.txt b/Kernel/CMakeLists.txt
index d57afe29a9..da64657a43 100644
--- a/Kernel/CMakeLists.txt
+++ b/Kernel/CMakeLists.txt
@@ -111,7 +111,8 @@ set(KERNEL_SOURCES
     FileSystem/Custody.cpp
     FileSystem/DevPtsFS/FileSystem.cpp
     FileSystem/DevPtsFS/Inode.cpp
-    FileSystem/Ext2FileSystem.cpp
+    FileSystem/Ext2FS/FileSystem.cpp
+    FileSystem/Ext2FS/Inode.cpp
     FileSystem/FATFS/FileSystem.cpp
     FileSystem/FATFS/Inode.cpp
     FileSystem/FIFO.cpp
diff --git a/Kernel/FileSystem/ext2_fs.h b/Kernel/FileSystem/Ext2FS/Definitions.h
index 7f4194dcf5..8d18b67355 100644
--- a/Kernel/FileSystem/ext2_fs.h
+++ b/Kernel/FileSystem/Ext2FS/Definitions.h
@@ -16,6 +16,8 @@
 #ifndef _LINUX_EXT2_FS_H
 #define _LINUX_EXT2_FS_H
 
+static constexpr size_t max_block_size = 4096;
+
 #include "ext2_types.h" /* Changed from linux/types.h */
 
 /*
@@ -510,18 +512,18 @@ struct ext2_super_block {
     __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...
-	 */
+     * 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 */
@@ -533,15 +535,15 @@ struct ext2_super_block {
     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.
-	 */
+     * 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.
-	 */
+     * 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 */
diff --git a/Kernel/FileSystem/Ext2FS/DirectoryEntry.h b/Kernel/FileSystem/Ext2FS/DirectoryEntry.h
new file mode 100644
index 0000000000..53d8f04504
--- /dev/null
+++ b/Kernel/FileSystem/Ext2FS/DirectoryEntry.h
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2022, Liav A. <liavalb@hotmail.co.il>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/OwnPtr.h>
+#include <AK/Types.h>
+#include <Kernel/FileSystem/Inode.h>
+#include <Kernel/KString.h>
+
+namespace Kernel {
+
+struct Ext2FSDirectoryEntry {
+    NonnullOwnPtr<KString> name;
+    InodeIndex inode_index { 0 };
+    u8 file_type { 0 };
+    u16 record_length { 0 };
+};
+
+}
diff --git a/Kernel/FileSystem/Ext2FS/FileSystem.cpp b/Kernel/FileSystem/Ext2FS/FileSystem.cpp
new file mode 100644
index 0000000000..8fe5f3e6f0
--- /dev/null
+++ b/Kernel/FileSystem/Ext2FS/FileSystem.cpp
@@ -0,0 +1,697 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2021, sin-ack <sin-ack@protonmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <Kernel/Debug.h>
+#include <Kernel/FileSystem/Ext2FS/FileSystem.h>
+#include <Kernel/FileSystem/Ext2FS/Inode.h>
+#include <Kernel/Process.h>
+#include <Kernel/UnixTypes.h>
+
+namespace Kernel {
+
+ErrorOr<NonnullLockRefPtr<FileSystem>> Ext2FS::try_create(OpenFileDescription& file_description)
+{
+    return TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) Ext2FS(file_description)));
+}
+
+Ext2FS::Ext2FS(OpenFileDescription& file_description)
+    : BlockBasedFileSystem(file_description)
+{
+}
+
+Ext2FS::~Ext2FS() = default;
+
+ErrorOr<void> Ext2FS::flush_super_block()
+{
+    MutexLocker locker(m_lock);
+    VERIFY((sizeof(ext2_super_block) % logical_block_size()) == 0);
+    auto super_block_buffer = UserOrKernelBuffer::for_kernel_buffer((u8*)&m_super_block);
+    return raw_write_blocks(2, (sizeof(ext2_super_block) / logical_block_size()), super_block_buffer);
+}
+
+ext2_group_desc const& Ext2FS::group_descriptor(GroupIndex group_index) const
+{
+    // FIXME: Should this fail gracefully somehow?
+    VERIFY(group_index <= m_block_group_count);
+    VERIFY(group_index > 0);
+    return block_group_descriptors()[group_index.value() - 1];
+}
+
+bool Ext2FS::is_initialized_while_locked()
+{
+    VERIFY(m_lock.is_locked());
+    return !m_root_inode.is_null();
+}
+
+ErrorOr<void> Ext2FS::initialize_while_locked()
+{
+    VERIFY(m_lock.is_locked());
+    VERIFY(!is_initialized_while_locked());
+
+    VERIFY((sizeof(ext2_super_block) % logical_block_size()) == 0);
+    auto super_block_buffer = UserOrKernelBuffer::for_kernel_buffer((u8*)&m_super_block);
+    TRY(raw_read_blocks(2, (sizeof(ext2_super_block) / logical_block_size()), super_block_buffer));
+
+    auto const& super_block = this->super_block();
+    if constexpr (EXT2_DEBUG) {
+        dmesgln("Ext2FS: super block magic: {:04x} (super block size: {})", super_block.s_magic, sizeof(ext2_super_block));
+    }
+    if (super_block.s_magic != EXT2_SUPER_MAGIC) {
+        dmesgln("Ext2FS: Bad super block magic");
+        return EINVAL;
+    }
+
+    if constexpr (EXT2_DEBUG) {
+        dmesgln("Ext2FS: {} inodes, {} blocks", super_block.s_inodes_count, super_block.s_blocks_count);
+        dmesgln("Ext2FS: Block size: {}", EXT2_BLOCK_SIZE(&super_block));
+        dmesgln("Ext2FS: First data block: {}", super_block.s_first_data_block);
+        dmesgln("Ext2FS: Inodes per block: {}", inodes_per_block());
+        dmesgln("Ext2FS: Inodes per group: {}", inodes_per_group());
+        dmesgln("Ext2FS: Free inodes: {}", super_block.s_free_inodes_count);
+        dmesgln("Ext2FS: Descriptors per block: {}", EXT2_DESC_PER_BLOCK(&super_block));
+        dmesgln("Ext2FS: Descriptor size: {}", EXT2_DESC_SIZE(&super_block));
+    }
+
+    set_block_size(EXT2_BLOCK_SIZE(&super_block));
+    set_fragment_size(EXT2_FRAG_SIZE(&super_block));
+
+    // Note: This depends on the block size being available.
+    TRY(BlockBasedFileSystem::initialize_while_locked());
+
+    VERIFY(block_size() <= (int)max_block_size);
+
+    m_block_group_count = ceil_div(super_block.s_blocks_count, super_block.s_blocks_per_group);
+
+    if (m_block_group_count == 0) {
+        dmesgln("Ext2FS: no block groups :(");
+        return EINVAL;
+    }
+
+    auto blocks_to_read = ceil_div(m_block_group_count * sizeof(ext2_group_desc), block_size());
+    BlockIndex first_block_of_bgdt = block_size() == 1024 ? 2 : 1;
+    m_cached_group_descriptor_table = TRY(KBuffer::try_create_with_size("Ext2FS: Block group descriptors"sv, block_size() * blocks_to_read, Memory::Region::Access::ReadWrite));
+    auto buffer = UserOrKernelBuffer::for_kernel_buffer(m_cached_group_descriptor_table->data());
+    TRY(read_blocks(first_block_of_bgdt, blocks_to_read, buffer));
+
+    if constexpr (EXT2_DEBUG) {
+        for (unsigned i = 1; i <= m_block_group_count; ++i) {
+            auto const& group = group_descriptor(i);
+            dbgln("Ext2FS: group[{}] ( block_bitmap: {}, inode_bitmap: {}, inode_table: {} )", i, group.bg_block_bitmap, group.bg_inode_bitmap, group.bg_inode_table);
+        }
+    }
+
+    m_root_inode = TRY(build_root_inode());
+    return {};
+}
+
+Inode& Ext2FS::root_inode()
+{
+    return *m_root_inode;
+}
+
+bool Ext2FS::find_block_containing_inode(InodeIndex inode, BlockIndex& block_index, unsigned& offset) const
+{
+    auto const& super_block = this->super_block();
+
+    if (inode != EXT2_ROOT_INO && inode < EXT2_FIRST_INO(&super_block))
+        return false;
+
+    if (inode > super_block.s_inodes_count)
+        return false;
+
+    auto const& bgd = group_descriptor(group_index_from_inode(inode));
+
+    u64 full_offset = ((inode.value() - 1) % inodes_per_group()) * inode_size();
+    block_index = bgd.bg_inode_table + (full_offset >> EXT2_BLOCK_SIZE_BITS(&super_block));
+    offset = full_offset & (block_size() - 1);
+
+    return true;
+}
+
+Ext2FS::BlockListShape Ext2FS::compute_block_list_shape(unsigned blocks) const
+{
+    BlockListShape shape;
+    unsigned const entries_per_block = EXT2_ADDR_PER_BLOCK(&super_block());
+    unsigned blocks_remaining = blocks;
+
+    shape.direct_blocks = min((unsigned)EXT2_NDIR_BLOCKS, blocks_remaining);
+    blocks_remaining -= shape.direct_blocks;
+    if (!blocks_remaining)
+        return shape;
+
+    shape.indirect_blocks = min(blocks_remaining, entries_per_block);
+    shape.meta_blocks += 1;
+    blocks_remaining -= shape.indirect_blocks;
+    if (!blocks_remaining)
+        return shape;
+
+    shape.doubly_indirect_blocks = min(blocks_remaining, entries_per_block * entries_per_block);
+    shape.meta_blocks += 1;
+    shape.meta_blocks += ceil_div(shape.doubly_indirect_blocks, entries_per_block);
+    blocks_remaining -= shape.doubly_indirect_blocks;
+    if (!blocks_remaining)
+        return shape;
+
+    shape.triply_indirect_blocks = min(blocks_remaining, entries_per_block * entries_per_block * entries_per_block);
+    shape.meta_blocks += 1;
+    shape.meta_blocks += ceil_div(shape.triply_indirect_blocks, entries_per_block * entries_per_block);
+    shape.meta_blocks += ceil_div(shape.triply_indirect_blocks, entries_per_block);
+    blocks_remaining -= shape.triply_indirect_blocks;
+    VERIFY(blocks_remaining == 0);
+    return shape;
+}
+
+u8 Ext2FS::internal_file_type_to_directory_entry_type(DirectoryEntryView const& entry) const
+{
+    switch (entry.file_type) {
+    case EXT2_FT_REG_FILE:
+        return DT_REG;
+    case EXT2_FT_DIR:
+        return DT_DIR;
+    case EXT2_FT_CHRDEV:
+        return DT_CHR;
+    case EXT2_FT_BLKDEV:
+        return DT_BLK;
+    case EXT2_FT_FIFO:
+        return DT_FIFO;
+    case EXT2_FT_SOCK:
+        return DT_SOCK;
+    case EXT2_FT_SYMLINK:
+        return DT_LNK;
+    default:
+        return DT_UNKNOWN;
+    }
+}
+
+Ext2FS::FeaturesReadOnly Ext2FS::get_features_readonly() const
+{
+    if (m_super_block.s_rev_level > 0)
+        return static_cast<Ext2FS::FeaturesReadOnly>(m_super_block.s_feature_ro_compat);
+    return Ext2FS::FeaturesReadOnly::None;
+}
+
+u64 Ext2FS::inodes_per_block() const
+{
+    return EXT2_INODES_PER_BLOCK(&super_block());
+}
+
+u64 Ext2FS::inodes_per_group() const
+{
+    return EXT2_INODES_PER_GROUP(&super_block());
+}
+
+u64 Ext2FS::inode_size() const
+{
+    return EXT2_INODE_SIZE(&super_block());
+}
+u64 Ext2FS::blocks_per_group() const
+{
+    return EXT2_BLOCKS_PER_GROUP(&super_block());
+}
+
+ErrorOr<void> Ext2FS::write_ext2_inode(InodeIndex inode, ext2_inode const& e2inode)
+{
+    BlockIndex block_index;
+    unsigned offset;
+    if (!find_block_containing_inode(inode, block_index, offset))
+        return EINVAL;
+    auto buffer = UserOrKernelBuffer::for_kernel_buffer(const_cast<u8*>((u8 const*)&e2inode));
+    return write_block(block_index, buffer, inode_size(), offset);
+}
+
+auto Ext2FS::allocate_blocks(GroupIndex preferred_group_index, size_t count) -> ErrorOr<Vector<BlockIndex>>
+{
+    dbgln_if(EXT2_DEBUG, "Ext2FS: allocate_blocks(preferred group: {}, count {})", preferred_group_index, count);
+    if (count == 0)
+        return Vector<BlockIndex> {};
+
+    Vector<BlockIndex> blocks;
+    TRY(blocks.try_ensure_capacity(count));
+
+    MutexLocker locker(m_lock);
+    auto group_index = preferred_group_index;
+
+    if (!group_descriptor(preferred_group_index).bg_free_blocks_count) {
+        group_index = 1;
+    }
+
+    while (blocks.size() < count) {
+        bool found_a_group = false;
+        if (group_descriptor(group_index).bg_free_blocks_count) {
+            found_a_group = true;
+        } else {
+            if (group_index == preferred_group_index)
+                group_index = 1;
+            for (; group_index <= m_block_group_count; group_index = GroupIndex { group_index.value() + 1 }) {
+                if (group_descriptor(group_index).bg_free_blocks_count) {
+                    found_a_group = true;
+                    break;
+                }
+            }
+        }
+
+        VERIFY(found_a_group);
+        auto const& bgd = group_descriptor(group_index);
+
+        auto* cached_bitmap = TRY(get_bitmap_block(bgd.bg_block_bitmap));
+
+        int blocks_in_group = min(blocks_per_group(), super_block().s_blocks_count);
+        auto block_bitmap = cached_bitmap->bitmap(blocks_in_group);
+
+        BlockIndex first_block_in_group = (group_index.value() - 1) * blocks_per_group() + first_block_index().value();
+        size_t free_region_size = 0;
+        auto first_unset_bit_index = block_bitmap.find_longest_range_of_unset_bits(count - blocks.size(), free_region_size);
+        VERIFY(first_unset_bit_index.has_value());
+        dbgln_if(EXT2_DEBUG, "Ext2FS: allocating free region of size: {} [{}]", free_region_size, group_index);
+        for (size_t i = 0; i < free_region_size; ++i) {
+            BlockIndex block_index = (first_unset_bit_index.value() + i) + first_block_in_group.value();
+            TRY(set_block_allocation_state(block_index, true));
+            blocks.unchecked_append(block_index);
+            dbgln_if(EXT2_DEBUG, "  allocated > {}", block_index);
+        }
+    }
+
+    VERIFY(blocks.size() == count);
+    return blocks;
+}
+
+ErrorOr<InodeIndex> Ext2FS::allocate_inode(GroupIndex preferred_group)
+{
+    dbgln_if(EXT2_DEBUG, "Ext2FS: allocate_inode(preferred_group: {})", preferred_group);
+    MutexLocker locker(m_lock);
+
+    // FIXME: We shouldn't refuse to allocate an inode if there is no group that can house the whole thing.
+    //        In those cases we should just spread it across multiple groups.
+    auto is_suitable_group = [this](auto group_index) {
+        auto& bgd = group_descriptor(group_index);
+        return bgd.bg_free_inodes_count && bgd.bg_free_blocks_count >= 1;
+    };
+
+    GroupIndex group_index;
+    if (preferred_group.value() && is_suitable_group(preferred_group)) {
+        group_index = preferred_group;
+    } else {
+        for (unsigned i = 1; i <= m_block_group_count; ++i) {
+            if (is_suitable_group(i)) {
+                group_index = i;
+                break;
+            }
+        }
+    }
+
+    if (!group_index) {
+        dmesgln("Ext2FS: allocate_inode: no suitable group found for new inode");
+        return ENOSPC;
+    }
+
+    dbgln_if(EXT2_DEBUG, "Ext2FS: allocate_inode: found suitable group [{}] for new inode :^)", group_index);
+
+    auto const& bgd = group_descriptor(group_index);
+    unsigned inodes_in_group = min(inodes_per_group(), super_block().s_inodes_count);
+    InodeIndex first_inode_in_group = (group_index.value() - 1) * inodes_per_group() + 1;
+
+    auto* cached_bitmap = TRY(get_bitmap_block(bgd.bg_inode_bitmap));
+    auto inode_bitmap = cached_bitmap->bitmap(inodes_in_group);
+    for (size_t i = 0; i < inode_bitmap.size(); ++i) {
+        if (inode_bitmap.get(i))
+            continue;
+        inode_bitmap.set(i, true);
+
+        auto inode_index = InodeIndex(first_inode_in_group.value() + i);
+
+        cached_bitmap->dirty = true;
+        m_super_block.s_free_inodes_count--;
+        m_super_block_dirty = true;
+        const_cast<ext2_group_desc&>(bgd).bg_free_inodes_count--;
+        m_block_group_descriptors_dirty = true;
+
+        // In case the inode cache had this cached as "non-existent", uncache that info.
+        m_inode_cache.remove(inode_index.value());
+
+        return inode_index;
+    }
+
+    dmesgln("Ext2FS: allocate_inode found no available inode, despite bgd claiming there are inodes :(");
+    return EIO;
+}
+
+Ext2FS::GroupIndex Ext2FS::group_index_from_block_index(BlockIndex block_index) const
+{
+    if (!block_index)
+        return 0;
+    return (block_index.value() - 1) / blocks_per_group() + 1;
+}
+
+auto Ext2FS::group_index_from_inode(InodeIndex inode) const -> GroupIndex
+{
+    if (!inode)
+        return 0;
+    return (inode.value() - 1) / inodes_per_group() + 1;
+}
+
+ErrorOr<bool> Ext2FS::get_inode_allocation_state(InodeIndex index) const
+{
+    MutexLocker locker(m_lock);
+    if (index == 0)
+        return EINVAL;
+    auto group_index = group_index_from_inode(index);
+    auto const& bgd = group_descriptor(group_index);
+    unsigned index_in_group = index.value() - ((group_index.value() - 1) * inodes_per_group());
+    unsigned bit_index = (index_in_group - 1) % inodes_per_group();
+
+    auto* cached_bitmap = TRY(const_cast<Ext2FS&>(*this).get_bitmap_block(bgd.bg_inode_bitmap));
+    return cached_bitmap->bitmap(inodes_per_group()).get(bit_index);
+}
+
+ErrorOr<void> Ext2FS::update_bitmap_block(BlockIndex bitmap_block, size_t bit_index, bool new_state, u32& super_block_counter, u16& group_descriptor_counter)
+{
+    auto* cached_bitmap = TRY(get_bitmap_block(bitmap_block));
+    bool current_state = cached_bitmap->bitmap(blocks_per_group()).get(bit_index);
+    if (current_state == new_state) {
+        dbgln("Ext2FS: Bit {} in bitmap block {} had unexpected state {}", bit_index, bitmap_block, current_state);
+        return EIO;
+    }
+    cached_bitmap->bitmap(blocks_per_group()).set(bit_index, new_state);
+    cached_bitmap->dirty = true;
+
+    if (new_state) {
+        --super_block_counter;
+        --group_descriptor_counter;
+    } else {
+        ++super_block_counter;
+        ++group_descriptor_counter;
+    }
+
+    m_super_block_dirty = true;
+    m_block_group_descriptors_dirty = true;
+    return {};
+}
+
+ErrorOr<void> Ext2FS::set_inode_allocation_state(InodeIndex inode_index, bool new_state)
+{
+    MutexLocker locker(m_lock);
+    auto group_index = group_index_from_inode(inode_index);
+    unsigned index_in_group = inode_index.value() - ((group_index.value() - 1) * inodes_per_group());
+    unsigned bit_index = (index_in_group - 1) % inodes_per_group();
+
+    dbgln_if(EXT2_DEBUG, "Ext2FS: set_inode_allocation_state: Inode {} -> {}", inode_index, new_state);
+    auto& bgd = const_cast<ext2_group_desc&>(group_descriptor(group_index));
+    return update_bitmap_block(bgd.bg_inode_bitmap, bit_index, new_state, m_super_block.s_free_inodes_count, bgd.bg_free_inodes_count);
+}
+
+Ext2FS::BlockIndex Ext2FS::first_block_index() const
+{
+    return block_size() == 1024 ? 1 : 0;
+}
+
+ErrorOr<Ext2FS::CachedBitmap*> Ext2FS::get_bitmap_block(BlockIndex bitmap_block_index)
+{
+    for (auto& cached_bitmap : m_cached_bitmaps) {
+        if (cached_bitmap->bitmap_block_index == bitmap_block_index)
+            return cached_bitmap.ptr();
+    }
+
+    auto block = TRY(KBuffer::try_create_with_size("Ext2FS: Cached bitmap block"sv, block_size(), Memory::Region::Access::ReadWrite));
+    auto buffer = UserOrKernelBuffer::for_kernel_buffer(block->data());
+    TRY(read_block(bitmap_block_index, &buffer, block_size()));
+    auto new_bitmap = TRY(adopt_nonnull_own_or_enomem(new (nothrow) CachedBitmap(bitmap_block_index, move(block))));
+    TRY(m_cached_bitmaps.try_append(move(new_bitmap)));
+    return m_cached_bitmaps.last().ptr();
+}
+
+ErrorOr<void> Ext2FS::set_block_allocation_state(BlockIndex block_index, bool new_state)
+{
+    VERIFY(block_index != 0);
+    MutexLocker locker(m_lock);
+
+    auto group_index = group_index_from_block_index(block_index);
+    unsigned index_in_group = (block_index.value() - first_block_index().value()) - ((group_index.value() - 1) * blocks_per_group());
+    unsigned bit_index = index_in_group % blocks_per_group();
+    auto& bgd = const_cast<ext2_group_desc&>(group_descriptor(group_index));
+
+    dbgln_if(EXT2_DEBUG, "Ext2FS: Block {} state -> {} (in bitmap block {})", block_index, new_state, bgd.bg_block_bitmap);
+    return update_bitmap_block(bgd.bg_block_bitmap, bit_index, new_state, m_super_block.s_free_blocks_count, bgd.bg_free_blocks_count);
+}
+
+ErrorOr<NonnullLockRefPtr<Inode>> Ext2FS::create_directory(Ext2FSInode& parent_inode, StringView name, mode_t mode, UserID uid, GroupID gid)
+{
+    MutexLocker locker(m_lock);
+    VERIFY(is_directory(mode));
+
+    auto inode = TRY(create_inode(parent_inode, name, mode, 0, uid, gid));
+
+    dbgln_if(EXT2_DEBUG, "Ext2FS: create_directory: created new directory named '{} with inode {}", name, inode->index());
+
+    Vector<Ext2FSDirectoryEntry> entries;
+    auto current_directory_name = TRY(KString::try_create("."sv));
+    TRY(entries.try_empend(move(current_directory_name), inode->index(), static_cast<u8>(EXT2_FT_DIR)));
+    auto parent_directory_name = TRY(KString::try_create(".."sv));
+    TRY(entries.try_empend(move(parent_directory_name), parent_inode.index(), static_cast<u8>(EXT2_FT_DIR)));
+
+    TRY(static_cast<Ext2FSInode&>(*inode).write_directory(entries));
+    TRY(parent_inode.increment_link_count());
+
+    auto& bgd = const_cast<ext2_group_desc&>(group_descriptor(group_index_from_inode(inode->identifier().index())));
+    ++bgd.bg_used_dirs_count;
+    m_block_group_descriptors_dirty = true;
+
+    return inode;
+}
+
+ErrorOr<NonnullLockRefPtr<Inode>> Ext2FS::create_inode(Ext2FSInode& parent_inode, StringView name, mode_t mode, dev_t dev, UserID uid, GroupID gid)
+{
+    if (name.length() > EXT2_NAME_LEN)
+        return ENAMETOOLONG;
+
+    if (parent_inode.m_raw_inode.i_links_count == 0)
+        return ENOENT;
+
+    ext2_inode e2inode {};
+    auto now = kgettimeofday().to_truncated_seconds();
+    e2inode.i_mode = mode;
+    e2inode.i_uid = uid.value();
+    e2inode.i_gid = gid.value();
+    e2inode.i_size = 0;
+    e2inode.i_atime = now;
+    e2inode.i_ctime = now;
+    e2inode.i_mtime = now;
+    e2inode.i_dtime = 0;
+    e2inode.i_flags = 0;
+
+    // For directories, add +1 link count for the "." entry in self.
+    e2inode.i_links_count = is_directory(mode);
+
+    if (is_character_device(mode))
+        e2inode.i_block[0] = dev;
+    else if (is_block_device(mode))
+        e2inode.i_block[1] = dev;
+
+    auto inode_id = TRY(allocate_inode());
+
+    dbgln_if(EXT2_DEBUG, "Ext2FS: writing initial metadata for inode {}", inode_id.value());
+    TRY(write_ext2_inode(inode_id, e2inode));
+
+    auto new_inode = TRY(get_inode({ fsid(), inode_id }));
+
+    dbgln_if(EXT2_DEBUG, "Ext2FS: Adding inode '{}' (mode {:o}) to parent directory {}", name, mode, parent_inode.index());
+    TRY(parent_inode.add_child(*new_inode, name, mode));
+    return new_inode;
+}
+
+void Ext2FS::uncache_inode(InodeIndex index)
+{
+    MutexLocker locker(m_lock);
+    m_inode_cache.remove(index);
+}
+
+unsigned Ext2FS::total_block_count() const
+{
+    MutexLocker locker(m_lock);
+    return super_block().s_blocks_count;
+}
+
+unsigned Ext2FS::free_block_count() const
+{
+    MutexLocker locker(m_lock);
+    return super_block().s_free_blocks_count;
+}
+
+unsigned Ext2FS::total_inode_count() const
+{
+    MutexLocker locker(m_lock);
+    return super_block().s_inodes_count;
+}
+
+unsigned Ext2FS::free_inode_count() const
+{
+    MutexLocker locker(m_lock);
+    return super_block().s_free_inodes_count;
+}
+
+ErrorOr<void> Ext2FS::prepare_to_clear_last_mount()
+{
+    MutexLocker locker(m_lock);
+    for (auto& it : m_inode_cache) {
+        if (it.value->ref_count() > 1)
+            return EBUSY;
+    }
+
+    BlockBasedFileSystem::remove_disk_cache_before_last_unmount();
+    m_inode_cache.clear();
+    m_root_inode = nullptr;
+    return {};
+}
+
+ErrorOr<void> Ext2FS::free_inode(Ext2FSInode& inode)
+{
+    MutexLocker locker(m_lock);
+    VERIFY(inode.m_raw_inode.i_links_count == 0);
+    dbgln_if(EXT2_DEBUG, "Ext2FS[{}]::free_inode(): Inode {} has no more links, time to delete!", fsid(), inode.index());
+
+    // Mark all blocks used by this inode as free.
+    {
+        auto blocks = TRY(inode.compute_block_list_with_meta_blocks());
+        for (auto block_index : blocks) {
+            VERIFY(block_index <= super_block().s_blocks_count);
+            if (block_index.value())
+                TRY(set_block_allocation_state(block_index, false));
+        }
+    }
+
+    // If the inode being freed is a directory, update block group directory counter.
+    if (inode.is_directory()) {
+        auto& bgd = const_cast<ext2_group_desc&>(group_descriptor(group_index_from_inode(inode.index())));
+        --bgd.bg_used_dirs_count;
+        dbgln_if(EXT2_DEBUG, "Ext2FS[{}]::free_inode(): Decremented bg_used_dirs_count to {} for inode {}", fsid(), bgd.bg_used_dirs_count, inode.index());
+        m_block_group_descriptors_dirty = true;
+    }
+
+    // NOTE: After this point, the inode metadata is wiped.
+    memset(&inode.m_raw_inode, 0, sizeof(ext2_inode));
+    inode.m_raw_inode.i_dtime = kgettimeofday().to_truncated_seconds();
+    TRY(write_ext2_inode(inode.index(), inode.m_raw_inode));
+
+    // Mark the inode as free.
+    TRY(set_inode_allocation_state(inode.index(), false));
+
+    return {};
+}
+
+void Ext2FS::flush_block_group_descriptor_table()
+{
+    MutexLocker locker(m_lock);
+    auto blocks_to_write = ceil_div(m_block_group_count * sizeof(ext2_group_desc), block_size());
+    auto first_block_of_bgdt = block_size() == 1024 ? 2 : 1;
+    auto buffer = UserOrKernelBuffer::for_kernel_buffer((u8*)block_group_descriptors());
+    if (auto result = write_blocks(first_block_of_bgdt, blocks_to_write, buffer); result.is_error())
+        dbgln("Ext2FS[{}]::flush_block_group_descriptor_table(): Failed to write blocks: {}", fsid(), result.error());
+}
+
+void Ext2FS::flush_writes()
+{
+    {
+        MutexLocker locker(m_lock);
+        if (m_super_block_dirty) {
+            auto result = flush_super_block();
+            if (result.is_error()) {
+                dbgln("Ext2FS[{}]::flush_writes(): Failed to write superblock: {}", fsid(), result.error());
+                // FIXME: We should handle this error.
+                VERIFY_NOT_REACHED();
+            }
+            m_super_block_dirty = false;
+        }
+        if (m_block_group_descriptors_dirty) {
+            flush_block_group_descriptor_table();
+            m_block_group_descriptors_dirty = false;
+        }
+        for (auto& cached_bitmap : m_cached_bitmaps) {
+            if (cached_bitmap->dirty) {
+                auto buffer = UserOrKernelBuffer::for_kernel_buffer(cached_bitmap->buffer->data());
+                if (auto result = write_block(cached_bitmap->bitmap_block_index, buffer, block_size()); result.is_error()) {
+                    dbgln("Ext2FS[{}]::flush_writes(): Failed to write blocks: {}", fsid(), result.error());
+                }
+                cached_bitmap->dirty = false;
+                dbgln_if(EXT2_DEBUG, "Ext2FS[{}]::flush_writes(): Flushed bitmap block {}", fsid(), cached_bitmap->bitmap_block_index);
+            }
+        }
+
+        // Uncache Inodes that are only kept alive by the index-to-inode lookup cache.
+        // We don't uncache Inodes that are being watched by at least one InodeWatcher.
+
+        // FIXME: It would be better to keep a capped number of Inodes around.
+        //        The problem is that they are quite heavy objects, and use a lot of heap memory
+        //        for their (child name lookup) and (block list) caches.
+
+        m_inode_cache.remove_all_matching([](InodeIndex, LockRefPtr<Ext2FSInode> const& cached_inode) {
+            // NOTE: If we're asked to look up an inode by number (via get_inode) and it turns out
+            //       to not exist, we remember the fact that it doesn't exist by caching a nullptr.
+            //       This seems like a reasonable time to uncache ideas about unknown inodes, so do that.
+            if (cached_inode == nullptr)
+                return true;
+
+            return cached_inode->ref_count() == 1 && !cached_inode->has_watchers();
+        });
+    }
+
+    BlockBasedFileSystem::flush_writes();
+}
+
+ErrorOr<NonnullLockRefPtr<Ext2FSInode>> Ext2FS::build_root_inode() const
+{
+    MutexLocker locker(m_lock);
+    BlockIndex block_index;
+    unsigned offset;
+    if (!find_block_containing_inode(EXT2_ROOT_INO, block_index, offset))
+        return EINVAL;
+
+    auto inode = TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) Ext2FSInode(const_cast<Ext2FS&>(*this), EXT2_ROOT_INO)));
+
+    auto buffer = UserOrKernelBuffer::for_kernel_buffer(reinterpret_cast<u8*>(&inode->m_raw_inode));
+    TRY(read_block(block_index, &buffer, sizeof(ext2_inode), offset));
+    return inode;
+}
+
+ErrorOr<NonnullLockRefPtr<Inode>> Ext2FS::get_inode(InodeIdentifier inode) const
+{
+    MutexLocker locker(m_lock);
+    VERIFY(inode.fsid() == fsid());
+    VERIFY(m_root_inode);
+
+    if (inode.index() == EXT2_ROOT_INO)
+        return *m_root_inode;
+
+    {
+        auto it = m_inode_cache.find(inode.index());
+        if (it != m_inode_cache.end()) {
+            if (!it->value)
+                return ENOENT;
+            return NonnullLockRefPtr<Inode> { *it->value };
+        }
+    }
+
+    auto inode_allocation_state = TRY(get_inode_allocation_state(inode.index()));
+
+    if (!inode_allocation_state) {
+        TRY(m_inode_cache.try_set(inode.index(), nullptr));
+        return ENOENT;
+    }
+
+    BlockIndex block_index;
+    unsigned offset;
+    if (!find_block_containing_inode(inode.index(), block_index, offset))
+        return EINVAL;
+
+    auto new_inode = TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) Ext2FSInode(const_cast<Ext2FS&>(*this), inode.index())));
+
+    auto buffer = UserOrKernelBuffer::for_kernel_buffer(reinterpret_cast<u8*>(&new_inode->m_raw_inode));
+    TRY(read_block(block_index, &buffer, sizeof(ext2_inode), offset));
+
+    TRY(m_inode_cache.try_set(inode.index(), new_inode));
+    return new_inode;
+}
+
+}
diff --git a/Kernel/FileSystem/Ext2FileSystem.h b/Kernel/FileSystem/Ext2FS/FileSystem.h
index 88bcf278c3..aa6efd90ec 100644
--- a/Kernel/FileSystem/Ext2FileSystem.h
+++ b/Kernel/FileSystem/Ext2FS/FileSystem.h
@@ -9,75 +9,14 @@
 #include <AK/Bitmap.h>
 #include <AK/HashMap.h>
 #include <Kernel/FileSystem/BlockBasedFileSystem.h>
+#include <Kernel/FileSystem/Ext2FS/Definitions.h>
 #include <Kernel/FileSystem/Inode.h>
-#include <Kernel/FileSystem/ext2_fs.h>
 #include <Kernel/KBuffer.h>
 #include <Kernel/UnixTypes.h>
 
-struct ext2_group_desc;
-struct ext2_inode;
-struct ext2_super_block;
-
 namespace Kernel {
 
-class Ext2FS;
-struct Ext2FSDirectoryEntry;
-
-class Ext2FSInode final : public Inode {
-    friend class Ext2FS;
-
-public:
-    virtual ~Ext2FSInode() override;
-
-    u64 size() const;
-    bool is_symlink() const { return Kernel::is_symlink(m_raw_inode.i_mode); }
-    bool is_directory() const { return Kernel::is_directory(m_raw_inode.i_mode); }
-
-private:
-    // ^Inode
-    virtual ErrorOr<size_t> read_bytes_locked(off_t, size_t, UserOrKernelBuffer& buffer, OpenFileDescription*) const override;
-    virtual InodeMetadata metadata() const override;
-    virtual ErrorOr<void> traverse_as_directory(Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)>) const override;
-    virtual ErrorOr<NonnullLockRefPtr<Inode>> lookup(StringView name) override;
-    virtual ErrorOr<void> flush_metadata() override;
-    virtual ErrorOr<size_t> write_bytes_locked(off_t, size_t, UserOrKernelBuffer const& data, OpenFileDescription*) override;
-    virtual ErrorOr<NonnullLockRefPtr<Inode>> create_child(StringView name, mode_t, dev_t, UserID, GroupID) override;
-    virtual ErrorOr<void> add_child(Inode& child, StringView name, mode_t) override;
-    virtual ErrorOr<void> remove_child(StringView name) override;
-    virtual ErrorOr<void> update_timestamps(Optional<time_t> atime, Optional<time_t> ctime, Optional<time_t> mtime) override;
-    virtual ErrorOr<void> increment_link_count() override;
-    virtual ErrorOr<void> decrement_link_count() override;
-    virtual ErrorOr<void> chmod(mode_t) override;
-    virtual ErrorOr<void> chown(UserID, GroupID) override;
-    virtual ErrorOr<void> truncate(u64) override;
-    virtual ErrorOr<int> get_block_address(int) override;
-
-    ErrorOr<void> write_directory(Vector<Ext2FSDirectoryEntry>&);
-    ErrorOr<void> populate_lookup_cache();
-    ErrorOr<void> resize(u64);
-    ErrorOr<void> write_indirect_block(BlockBasedFileSystem::BlockIndex, Span<BlockBasedFileSystem::BlockIndex>);
-    ErrorOr<void> grow_doubly_indirect_block(BlockBasedFileSystem::BlockIndex, size_t, Span<BlockBasedFileSystem::BlockIndex>, Vector<BlockBasedFileSystem::BlockIndex>&, unsigned&);
-    ErrorOr<void> shrink_doubly_indirect_block(BlockBasedFileSystem::BlockIndex, size_t, size_t, unsigned&);
-    ErrorOr<void> grow_triply_indirect_block(BlockBasedFileSystem::BlockIndex, size_t, Span<BlockBasedFileSystem::BlockIndex>, Vector<BlockBasedFileSystem::BlockIndex>&, unsigned&);
-    ErrorOr<void> shrink_triply_indirect_block(BlockBasedFileSystem::BlockIndex, size_t, size_t, unsigned&);
-    ErrorOr<void> flush_block_list();
-
-    ErrorOr<void> compute_block_list_with_exclusive_locking();
-    ErrorOr<Vector<BlockBasedFileSystem::BlockIndex>> compute_block_list() const;
-    ErrorOr<Vector<BlockBasedFileSystem::BlockIndex>> compute_block_list_with_meta_blocks() const;
-    ErrorOr<Vector<BlockBasedFileSystem::BlockIndex>> compute_block_list_impl(bool include_block_list_blocks) const;
-    ErrorOr<Vector<BlockBasedFileSystem::BlockIndex>> compute_block_list_impl_internal(ext2_inode const&, bool include_block_list_blocks) const;
-
-    Ext2FS& fs();
-    Ext2FS const& fs() const;
-    Ext2FSInode(Ext2FS&, InodeIndex);
-
-    Vector<BlockBasedFileSystem::BlockIndex> m_block_list;
-    HashMap<NonnullOwnPtr<KString>, InodeIndex> m_lookup_cache;
-    ext2_inode m_raw_inode {};
-
-    Mutex m_block_list_lock { "BlockList"sv };
-};
+class Ext2FSInode;
 
 class Ext2FS final : public BlockBasedFileSystem {
     friend class Ext2FSInode;
@@ -103,6 +42,9 @@ public:
 
     FeaturesReadOnly get_features_readonly() const;
 
+    virtual StringView class_name() const override { return "Ext2FS"sv; }
+    virtual Inode& root_inode() override;
+
 private:
     AK_TYPEDEF_DISTINCT_ORDERED_ID(unsigned, GroupIndex);
 
@@ -129,8 +71,6 @@ private:
     virtual bool is_initialized_while_locked() override;
 
     virtual ErrorOr<void> prepare_to_clear_last_mount() override;
-    virtual StringView class_name() const override { return "Ext2FS"sv; }
-    virtual Ext2FSInode& root_inode() override;
     ErrorOr<NonnullLockRefPtr<Inode>> get_inode(InodeIdentifier) const;
     ErrorOr<NonnullLockRefPtr<Inode>> create_inode(Ext2FSInode& parent_inode, StringView name, mode_t, dev_t, UserID, GroupID);
     ErrorOr<NonnullLockRefPtr<Inode>> create_directory(Ext2FSInode& parent_inode, StringView name, mode_t, UserID, GroupID);
@@ -188,14 +128,4 @@ private:
     LockRefPtr<Ext2FSInode> m_root_inode;
 };
 
-inline Ext2FS& Ext2FSInode::fs()
-{
-    return static_cast<Ext2FS&>(Inode::fs());
-}
-
-inline Ext2FS const& Ext2FSInode::fs() const
-{
-    return static_cast<Ext2FS const&>(Inode::fs());
-}
-
 }
diff --git a/Kernel/FileSystem/Ext2FileSystem.cpp b/Kernel/FileSystem/Ext2FS/Inode.cpp
index 15aa39c1e2..ecf28273d1 100644
--- a/Kernel/FileSystem/Ext2FileSystem.cpp
+++ b/Kernel/FileSystem/Ext2FS/Inode.cpp
@@ -5,31 +5,17 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/HashMap.h>
 #include <AK/MemoryStream.h>
-#include <AK/StdLibExtras.h>
-#include <AK/StringView.h>
 #include <Kernel/API/POSIX/errno.h>
 #include <Kernel/Debug.h>
-#include <Kernel/Devices/BlockDevice.h>
-#include <Kernel/FileSystem/Ext2FileSystem.h>
-#include <Kernel/FileSystem/OpenFileDescription.h>
-#include <Kernel/FileSystem/ext2_fs.h>
-#include <Kernel/Process.h>
+#include <Kernel/FileSystem/Ext2FS/Inode.h>
+#include <Kernel/FileSystem/InodeMetadata.h>
 #include <Kernel/UnixTypes.h>
 
 namespace Kernel {
 
-static constexpr size_t max_block_size = 4096;
 static constexpr size_t max_inline_symlink_length = 60;
 
-struct Ext2FSDirectoryEntry {
-    NonnullOwnPtr<KString> name;
-    InodeIndex inode_index { 0 };
-    u8 file_type { 0 };
-    u16 record_length { 0 };
-};
-
 static u8 to_ext2_file_type(mode_t mode)
 {
     if (is_regular_file(mode))
@@ -49,158 +35,6 @@ static u8 to_ext2_file_type(mode_t mode)
     return EXT2_FT_UNKNOWN;
 }
 
-ErrorOr<NonnullLockRefPtr<FileSystem>> Ext2FS::try_create(OpenFileDescription& file_description)
-{
-    return TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) Ext2FS(file_description)));
-}
-
-Ext2FS::Ext2FS(OpenFileDescription& file_description)
-    : BlockBasedFileSystem(file_description)
-{
-}
-
-Ext2FS::~Ext2FS() = default;
-
-ErrorOr<void> Ext2FS::flush_super_block()
-{
-    MutexLocker locker(m_lock);
-    VERIFY((sizeof(ext2_super_block) % logical_block_size()) == 0);
-    auto super_block_buffer = UserOrKernelBuffer::for_kernel_buffer((u8*)&m_super_block);
-    return raw_write_blocks(2, (sizeof(ext2_super_block) / logical_block_size()), super_block_buffer);
-}
-
-ext2_group_desc const& Ext2FS::group_descriptor(GroupIndex group_index) const
-{
-    // FIXME: Should this fail gracefully somehow?
-    VERIFY(group_index <= m_block_group_count);
-    VERIFY(group_index > 0);
-    return block_group_descriptors()[group_index.value() - 1];
-}
-
-bool Ext2FS::is_initialized_while_locked()
-{
-    VERIFY(m_lock.is_locked());
-    return !m_root_inode.is_null();
-}
-
-ErrorOr<void> Ext2FS::initialize_while_locked()
-{
-    VERIFY(m_lock.is_locked());
-    VERIFY(!is_initialized_while_locked());
-
-    VERIFY((sizeof(ext2_super_block) % logical_block_size()) == 0);
-    auto super_block_buffer = UserOrKernelBuffer::for_kernel_buffer((u8*)&m_super_block);
-    TRY(raw_read_blocks(2, (sizeof(ext2_super_block) / logical_block_size()), super_block_buffer));
-
-    auto const& super_block = this->super_block();
-    if constexpr (EXT2_DEBUG) {
-        dmesgln("Ext2FS: super block magic: {:04x} (super block size: {})", super_block.s_magic, sizeof(ext2_super_block));
-    }
-    if (super_block.s_magic != EXT2_SUPER_MAGIC) {
-        dmesgln("Ext2FS: Bad super block magic");
-        return EINVAL;
-    }
-
-    if constexpr (EXT2_DEBUG) {
-        dmesgln("Ext2FS: {} inodes, {} blocks", super_block.s_inodes_count, super_block.s_blocks_count);
-        dmesgln("Ext2FS: Block size: {}", EXT2_BLOCK_SIZE(&super_block));
-        dmesgln("Ext2FS: First data block: {}", super_block.s_first_data_block);
-        dmesgln("Ext2FS: Inodes per block: {}", inodes_per_block());
-        dmesgln("Ext2FS: Inodes per group: {}", inodes_per_group());
-        dmesgln("Ext2FS: Free inodes: {}", super_block.s_free_inodes_count);
-        dmesgln("Ext2FS: Descriptors per block: {}", EXT2_DESC_PER_BLOCK(&super_block));
-        dmesgln("Ext2FS: Descriptor size: {}", EXT2_DESC_SIZE(&super_block));
-    }
-
-    set_block_size(EXT2_BLOCK_SIZE(&super_block));
-    set_fragment_size(EXT2_FRAG_SIZE(&super_block));
-
-    // Note: This depends on the block size being available.
-    TRY(BlockBasedFileSystem::initialize_while_locked());
-
-    VERIFY(block_size() <= (int)max_block_size);
-
-    m_block_group_count = ceil_div(super_block.s_blocks_count, super_block.s_blocks_per_group);
-
-    if (m_block_group_count == 0) {
-        dmesgln("Ext2FS: no block groups :(");
-        return EINVAL;
-    }
-
-    auto blocks_to_read = ceil_div(m_block_group_count * sizeof(ext2_group_desc), block_size());
-    BlockIndex first_block_of_bgdt = block_size() == 1024 ? 2 : 1;
-    m_cached_group_descriptor_table = TRY(KBuffer::try_create_with_size("Ext2FS: Block group descriptors"sv, block_size() * blocks_to_read, Memory::Region::Access::ReadWrite));
-    auto buffer = UserOrKernelBuffer::for_kernel_buffer(m_cached_group_descriptor_table->data());
-    TRY(read_blocks(first_block_of_bgdt, blocks_to_read, buffer));
-
-    if constexpr (EXT2_DEBUG) {
-        for (unsigned i = 1; i <= m_block_group_count; ++i) {
-            auto const& group = group_descriptor(i);
-            dbgln("Ext2FS: group[{}] ( block_bitmap: {}, inode_bitmap: {}, inode_table: {} )", i, group.bg_block_bitmap, group.bg_inode_bitmap, group.bg_inode_table);
-        }
-    }
-
-    m_root_inode = TRY(build_root_inode());
-    return {};
-}
-
-Ext2FSInode& Ext2FS::root_inode()
-{
-    return *m_root_inode;
-}
-
-bool Ext2FS::find_block_containing_inode(InodeIndex inode, BlockIndex& block_index, unsigned& offset) const
-{
-    auto const& super_block = this->super_block();
-
-    if (inode != EXT2_ROOT_INO && inode < EXT2_FIRST_INO(&super_block))
-        return false;
-
-    if (inode > super_block.s_inodes_count)
-        return false;
-
-    auto const& bgd = group_descriptor(group_index_from_inode(inode));
-
-    u64 full_offset = ((inode.value() - 1) % inodes_per_group()) * inode_size();
-    block_index = bgd.bg_inode_table + (full_offset >> EXT2_BLOCK_SIZE_BITS(&super_block));
-    offset = full_offset & (block_size() - 1);
-
-    return true;
-}
-
-Ext2FS::BlockListShape Ext2FS::compute_block_list_shape(unsigned blocks) const
-{
-    BlockListShape shape;
-    unsigned const entries_per_block = EXT2_ADDR_PER_BLOCK(&super_block());
-    unsigned blocks_remaining = blocks;
-
-    shape.direct_blocks = min((unsigned)EXT2_NDIR_BLOCKS, blocks_remaining);
-    blocks_remaining -= shape.direct_blocks;
-    if (!blocks_remaining)
-        return shape;
-
-    shape.indirect_blocks = min(blocks_remaining, entries_per_block);
-    shape.meta_blocks += 1;
-    blocks_remaining -= shape.indirect_blocks;
-    if (!blocks_remaining)
-        return shape;
-
-    shape.doubly_indirect_blocks = min(blocks_remaining, entries_per_block * entries_per_block);
-    shape.meta_blocks += 1;
-    shape.meta_blocks += ceil_div(shape.doubly_indirect_blocks, entries_per_block);
-    blocks_remaining -= shape.doubly_indirect_blocks;
-    if (!blocks_remaining)
-        return shape;
-
-    shape.triply_indirect_blocks = min(blocks_remaining, entries_per_block * entries_per_block * entries_per_block);
-    shape.meta_blocks += 1;
-    shape.meta_blocks += ceil_div(shape.triply_indirect_blocks, entries_per_block * entries_per_block);
-    shape.meta_blocks += ceil_div(shape.triply_indirect_blocks, entries_per_block);
-    blocks_remaining -= shape.triply_indirect_blocks;
-    VERIFY(blocks_remaining == 0);
-    return shape;
-}
-
 ErrorOr<void> Ext2FSInode::write_indirect_block(BlockBasedFileSystem::BlockIndex block, Span<BlockBasedFileSystem::BlockIndex> blocks_indices)
 {
     auto const entries_per_block = EXT2_ADDR_PER_BLOCK(&fs().super_block());
@@ -530,7 +364,7 @@ ErrorOr<Vector<Ext2FS::BlockIndex>> Ext2FSInode::compute_block_list_impl_interna
     // If the path is longer than 60 characters, a block is allocated, and the
     // block contains the destination path. The file size corresponds to the
     // path length of the destination.
-    if (::is_symlink(e2inode.i_mode) && e2inode.i_blocks == 0)
+    if (Kernel::is_symlink(e2inode.i_mode) && e2inode.i_blocks == 0)
         block_count = 0;
 
     dbgln_if(EXT2_DEBUG, "Ext2FSInode[{}]::block_list_for_inode(): i_size={}, i_blocks={}, block_count={}", identifier(), e2inode.i_size, e2inode.i_blocks, block_count);
@@ -613,100 +447,6 @@ ErrorOr<Vector<Ext2FS::BlockIndex>> Ext2FSInode::compute_block_list_impl_interna
     return list;
 }
 
-ErrorOr<void> Ext2FS::free_inode(Ext2FSInode& inode)
-{
-    MutexLocker locker(m_lock);
-    VERIFY(inode.m_raw_inode.i_links_count == 0);
-    dbgln_if(EXT2_DEBUG, "Ext2FS[{}]::free_inode(): Inode {} has no more links, time to delete!", fsid(), inode.index());
-
-    // Mark all blocks used by this inode as free.
-    {
-        auto blocks = TRY(inode.compute_block_list_with_meta_blocks());
-        for (auto block_index : blocks) {
-            VERIFY(block_index <= super_block().s_blocks_count);
-            if (block_index.value())
-                TRY(set_block_allocation_state(block_index, false));
-        }
-    }
-
-    // If the inode being freed is a directory, update block group directory counter.
-    if (inode.is_directory()) {
-        auto& bgd = const_cast<ext2_group_desc&>(group_descriptor(group_index_from_inode(inode.index())));
-        --bgd.bg_used_dirs_count;
-        dbgln_if(EXT2_DEBUG, "Ext2FS[{}]::free_inode(): Decremented bg_used_dirs_count to {} for inode {}", fsid(), bgd.bg_used_dirs_count, inode.index());
-        m_block_group_descriptors_dirty = true;
-    }
-
-    // NOTE: After this point, the inode metadata is wiped.
-    memset(&inode.m_raw_inode, 0, sizeof(ext2_inode));
-    inode.m_raw_inode.i_dtime = kgettimeofday().to_truncated_seconds();
-    TRY(write_ext2_inode(inode.index(), inode.m_raw_inode));
-
-    // Mark the inode as free.
-    TRY(set_inode_allocation_state(inode.index(), false));
-
-    return {};
-}
-
-void Ext2FS::flush_block_group_descriptor_table()
-{
-    MutexLocker locker(m_lock);
-    auto blocks_to_write = ceil_div(m_block_group_count * sizeof(ext2_group_desc), block_size());
-    auto first_block_of_bgdt = block_size() == 1024 ? 2 : 1;
-    auto buffer = UserOrKernelBuffer::for_kernel_buffer((u8*)block_group_descriptors());
-    if (auto result = write_blocks(first_block_of_bgdt, blocks_to_write, buffer); result.is_error())
-        dbgln("Ext2FS[{}]::flush_block_group_descriptor_table(): Failed to write blocks: {}", fsid(), result.error());
-}
-
-void Ext2FS::flush_writes()
-{
-    {
-        MutexLocker locker(m_lock);
-        if (m_super_block_dirty) {
-            auto result = flush_super_block();
-            if (result.is_error()) {
-                dbgln("Ext2FS[{}]::flush_writes(): Failed to write superblock: {}", fsid(), result.error());
-                // FIXME: We should handle this error.
-                VERIFY_NOT_REACHED();
-            }
-            m_super_block_dirty = false;
-        }
-        if (m_block_group_descriptors_dirty) {
-            flush_block_group_descriptor_table();
-            m_block_group_descriptors_dirty = false;
-        }
-        for (auto& cached_bitmap : m_cached_bitmaps) {
-            if (cached_bitmap->dirty) {
-                auto buffer = UserOrKernelBuffer::for_kernel_buffer(cached_bitmap->buffer->data());
-                if (auto result = write_block(cached_bitmap->bitmap_block_index, buffer, block_size()); result.is_error()) {
-                    dbgln("Ext2FS[{}]::flush_writes(): Failed to write blocks: {}", fsid(), result.error());
-                }
-                cached_bitmap->dirty = false;
-                dbgln_if(EXT2_DEBUG, "Ext2FS[{}]::flush_writes(): Flushed bitmap block {}", fsid(), cached_bitmap->bitmap_block_index);
-            }
-        }
-
-        // Uncache Inodes that are only kept alive by the index-to-inode lookup cache.
-        // We don't uncache Inodes that are being watched by at least one InodeWatcher.
-
-        // FIXME: It would be better to keep a capped number of Inodes around.
-        //        The problem is that they are quite heavy objects, and use a lot of heap memory
-        //        for their (child name lookup) and (block list) caches.
-
-        m_inode_cache.remove_all_matching([](InodeIndex, LockRefPtr<Ext2FSInode> const& cached_inode) {
-            // NOTE: If we're asked to look up an inode by number (via get_inode) and it turns out
-            //       to not exist, we remember the fact that it doesn't exist by caching a nullptr.
-            //       This seems like a reasonable time to uncache ideas about unknown inodes, so do that.
-            if (cached_inode == nullptr)
-                return true;
-
-            return cached_inode->ref_count() == 1 && !cached_inode->has_watchers();
-        });
-    }
-
-    BlockBasedFileSystem::flush_writes();
-}
-
 Ext2FSInode::Ext2FSInode(Ext2FS& fs, InodeIndex index)
     : Inode(fs, index)
 {
@@ -770,60 +510,6 @@ ErrorOr<void> Ext2FSInode::flush_metadata()
     return {};
 }
 
-ErrorOr<NonnullLockRefPtr<Ext2FSInode>> Ext2FS::build_root_inode() const
-{
-    MutexLocker locker(m_lock);
-    BlockIndex block_index;
-    unsigned offset;
-    if (!find_block_containing_inode(EXT2_ROOT_INO, block_index, offset))
-        return EINVAL;
-
-    auto inode = TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) Ext2FSInode(const_cast<Ext2FS&>(*this), EXT2_ROOT_INO)));
-
-    auto buffer = UserOrKernelBuffer::for_kernel_buffer(reinterpret_cast<u8*>(&inode->m_raw_inode));
-    TRY(read_block(block_index, &buffer, sizeof(ext2_inode), offset));
-    return inode;
-}
-
-ErrorOr<NonnullLockRefPtr<Inode>> Ext2FS::get_inode(InodeIdentifier inode) const
-{
-    MutexLocker locker(m_lock);
-    VERIFY(inode.fsid() == fsid());
-    VERIFY(m_root_inode);
-
-    if (inode.index() == EXT2_ROOT_INO)
-        return *m_root_inode;
-
-    {
-        auto it = m_inode_cache.find(inode.index());
-        if (it != m_inode_cache.end()) {
-            if (!it->value)
-                return ENOENT;
-            return NonnullLockRefPtr<Inode> { *it->value };
-        }
-    }
-
-    auto inode_allocation_state = TRY(get_inode_allocation_state(inode.index()));
-
-    if (!inode_allocation_state) {
-        TRY(m_inode_cache.try_set(inode.index(), nullptr));
-        return ENOENT;
-    }
-
-    BlockIndex block_index;
-    unsigned offset;
-    if (!find_block_containing_inode(inode.index(), block_index, offset))
-        return EINVAL;
-
-    auto new_inode = TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) Ext2FSInode(const_cast<Ext2FS&>(*this), inode.index())));
-
-    auto buffer = UserOrKernelBuffer::for_kernel_buffer(reinterpret_cast<u8*>(&new_inode->m_raw_inode));
-    TRY(read_block(block_index, &buffer, sizeof(ext2_inode), offset));
-
-    TRY(m_inode_cache.try_set(inode.index(), new_inode));
-    return new_inode;
-}
-
 ErrorOr<void> Ext2FSInode::compute_block_list_with_exclusive_locking()
 {
     // Note: We verify that the inode mutex is being held locked. Because only the read_bytes_locked()
@@ -1043,35 +729,6 @@ ErrorOr<size_t> Ext2FSInode::write_bytes_locked(off_t offset, size_t count, User
     return nwritten;
 }
 
-u8 Ext2FS::internal_file_type_to_directory_entry_type(DirectoryEntryView const& entry) const
-{
-    switch (entry.file_type) {
-    case EXT2_FT_REG_FILE:
-        return DT_REG;
-    case EXT2_FT_DIR:
-        return DT_DIR;
-    case EXT2_FT_CHRDEV:
-        return DT_CHR;
-    case EXT2_FT_BLKDEV:
-        return DT_BLK;
-    case EXT2_FT_FIFO:
-        return DT_FIFO;
-    case EXT2_FT_SOCK:
-        return DT_SOCK;
-    case EXT2_FT_SYMLINK:
-        return DT_LNK;
-    default:
-        return DT_UNKNOWN;
-    }
-}
-
-Ext2FS::FeaturesReadOnly Ext2FS::get_features_readonly() const
-{
-    if (m_super_block.s_rev_level > 0)
-        return static_cast<Ext2FS::FeaturesReadOnly>(m_super_block.s_feature_ro_compat);
-    return Ext2FS::FeaturesReadOnly::None;
-}
-
 ErrorOr<void> Ext2FSInode::traverse_as_directory(Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)> callback) const
 {
     VERIFY(is_directory());
@@ -1088,14 +745,15 @@ ErrorOr<void> Ext2FSInode::traverse_as_directory(Function<ErrorOr<void>(FileSyst
     for (u64 offset = 0; offset < file_size; offset += block_size) {
         TRY(read_bytes(offset, block_size, buf, nullptr));
 
-        auto* entry = reinterpret_cast<ext2_dir_entry_2*>(buffer);
-        auto* entries_end = reinterpret_cast<ext2_dir_entry_2*>(buffer + block_size);
+        using ext2_extended_dir_entry = ext2_dir_entry_2;
+        auto* entry = reinterpret_cast<ext2_extended_dir_entry*>(buffer);
+        auto* entries_end = reinterpret_cast<ext2_extended_dir_entry*>(buffer + block_size);
         while (entry < entries_end) {
             if (entry->inode != 0) {
                 dbgln_if(EXT2_DEBUG, "Ext2FSInode[{}]::traverse_as_directory(): inode {}, name_len: {}, rec_len: {}, file_type: {}, name: {}", identifier(), entry->inode, entry->name_len, entry->rec_len, entry->file_type, StringView(entry->name, entry->name_len));
                 TRY(callback({ { entry->name, entry->name_len }, { fsid(), entry->inode }, entry->file_type }));
             }
-            entry = (ext2_dir_entry_2*)((char*)entry + entry->rec_len);
+            entry = (ext2_extended_dir_entry*)((char*)entry + entry->rec_len);
         }
     }
 
@@ -1161,7 +819,7 @@ ErrorOr<void> Ext2FSInode::write_directory(Vector<Ext2FSDirectoryEntry>& entries
 
 ErrorOr<NonnullLockRefPtr<Inode>> Ext2FSInode::create_child(StringView name, mode_t mode, dev_t dev, UserID uid, GroupID gid)
 {
-    if (::is_directory(mode))
+    if (Kernel::is_directory(mode))
         return fs().create_directory(*this, name, mode, uid, gid);
     return fs().create_inode(*this, name, mode, dev, uid, gid);
 }
@@ -1234,314 +892,6 @@ ErrorOr<void> Ext2FSInode::remove_child(StringView name)
     return {};
 }
 
-u64 Ext2FS::inodes_per_block() const
-{
-    return EXT2_INODES_PER_BLOCK(&super_block());
-}
-
-u64 Ext2FS::inodes_per_group() const
-{
-    return EXT2_INODES_PER_GROUP(&super_block());
-}
-
-u64 Ext2FS::inode_size() const
-{
-    return EXT2_INODE_SIZE(&super_block());
-}
-u64 Ext2FS::blocks_per_group() const
-{
-    return EXT2_BLOCKS_PER_GROUP(&super_block());
-}
-
-ErrorOr<void> Ext2FS::write_ext2_inode(InodeIndex inode, ext2_inode const& e2inode)
-{
-    BlockIndex block_index;
-    unsigned offset;
-    if (!find_block_containing_inode(inode, block_index, offset))
-        return EINVAL;
-    auto buffer = UserOrKernelBuffer::for_kernel_buffer(const_cast<u8*>((u8 const*)&e2inode));
-    return write_block(block_index, buffer, inode_size(), offset);
-}
-
-auto Ext2FS::allocate_blocks(GroupIndex preferred_group_index, size_t count) -> ErrorOr<Vector<BlockIndex>>
-{
-    dbgln_if(EXT2_DEBUG, "Ext2FS: allocate_blocks(preferred group: {}, count {})", preferred_group_index, count);
-    if (count == 0)
-        return Vector<BlockIndex> {};
-
-    Vector<BlockIndex> blocks;
-    TRY(blocks.try_ensure_capacity(count));
-
-    MutexLocker locker(m_lock);
-    auto group_index = preferred_group_index;
-
-    if (!group_descriptor(preferred_group_index).bg_free_blocks_count) {
-        group_index = 1;
-    }
-
-    while (blocks.size() < count) {
-        bool found_a_group = false;
-        if (group_descriptor(group_index).bg_free_blocks_count) {
-            found_a_group = true;
-        } else {
-            if (group_index == preferred_group_index)
-                group_index = 1;
-            for (; group_index <= m_block_group_count; group_index = GroupIndex { group_index.value() + 1 }) {
-                if (group_descriptor(group_index).bg_free_blocks_count) {
-                    found_a_group = true;
-                    break;
-                }
-            }
-        }
-
-        VERIFY(found_a_group);
-        auto const& bgd = group_descriptor(group_index);
-
-        auto* cached_bitmap = TRY(get_bitmap_block(bgd.bg_block_bitmap));
-
-        int blocks_in_group = min(blocks_per_group(), super_block().s_blocks_count);
-        auto block_bitmap = cached_bitmap->bitmap(blocks_in_group);
-
-        BlockIndex first_block_in_group = (group_index.value() - 1) * blocks_per_group() + first_block_index().value();
-        size_t free_region_size = 0;
-        auto first_unset_bit_index = block_bitmap.find_longest_range_of_unset_bits(count - blocks.size(), free_region_size);
-        VERIFY(first_unset_bit_index.has_value());
-        dbgln_if(EXT2_DEBUG, "Ext2FS: allocating free region of size: {} [{}]", free_region_size, group_index);
-        for (size_t i = 0; i < free_region_size; ++i) {
-            BlockIndex block_index = (first_unset_bit_index.value() + i) + first_block_in_group.value();
-            TRY(set_block_allocation_state(block_index, true));
-            blocks.unchecked_append(block_index);
-            dbgln_if(EXT2_DEBUG, "  allocated > {}", block_index);
-        }
-    }
-
-    VERIFY(blocks.size() == count);
-    return blocks;
-}
-
-ErrorOr<InodeIndex> Ext2FS::allocate_inode(GroupIndex preferred_group)
-{
-    dbgln_if(EXT2_DEBUG, "Ext2FS: allocate_inode(preferred_group: {})", preferred_group);
-    MutexLocker locker(m_lock);
-
-    // FIXME: We shouldn't refuse to allocate an inode if there is no group that can house the whole thing.
-    //        In those cases we should just spread it across multiple groups.
-    auto is_suitable_group = [this](auto group_index) {
-        auto& bgd = group_descriptor(group_index);
-        return bgd.bg_free_inodes_count && bgd.bg_free_blocks_count >= 1;
-    };
-
-    GroupIndex group_index;
-    if (preferred_group.value() && is_suitable_group(preferred_group)) {
-        group_index = preferred_group;
-    } else {
-        for (unsigned i = 1; i <= m_block_group_count; ++i) {
-            if (is_suitable_group(i)) {
-                group_index = i;
-                break;
-            }
-        }
-    }
-
-    if (!group_index) {
-        dmesgln("Ext2FS: allocate_inode: no suitable group found for new inode");
-        return ENOSPC;
-    }
-
-    dbgln_if(EXT2_DEBUG, "Ext2FS: allocate_inode: found suitable group [{}] for new inode :^)", group_index);
-
-    auto const& bgd = group_descriptor(group_index);
-    unsigned inodes_in_group = min(inodes_per_group(), super_block().s_inodes_count);
-    InodeIndex first_inode_in_group = (group_index.value() - 1) * inodes_per_group() + 1;
-
-    auto* cached_bitmap = TRY(get_bitmap_block(bgd.bg_inode_bitmap));
-    auto inode_bitmap = cached_bitmap->bitmap(inodes_in_group);
-    for (size_t i = 0; i < inode_bitmap.size(); ++i) {
-        if (inode_bitmap.get(i))
-            continue;
-        inode_bitmap.set(i, true);
-
-        auto inode_index = InodeIndex(first_inode_in_group.value() + i);
-
-        cached_bitmap->dirty = true;
-        m_super_block.s_free_inodes_count--;
-        m_super_block_dirty = true;
-        const_cast<ext2_group_desc&>(bgd).bg_free_inodes_count--;
-        m_block_group_descriptors_dirty = true;
-
-        // In case the inode cache had this cached as "non-existent", uncache that info.
-        m_inode_cache.remove(inode_index.value());
-
-        return inode_index;
-    }
-
-    dmesgln("Ext2FS: allocate_inode found no available inode, despite bgd claiming there are inodes :(");
-    return EIO;
-}
-
-Ext2FS::GroupIndex Ext2FS::group_index_from_block_index(BlockIndex block_index) const
-{
-    if (!block_index)
-        return 0;
-    return (block_index.value() - 1) / blocks_per_group() + 1;
-}
-
-auto Ext2FS::group_index_from_inode(InodeIndex inode) const -> GroupIndex
-{
-    if (!inode)
-        return 0;
-    return (inode.value() - 1) / inodes_per_group() + 1;
-}
-
-ErrorOr<bool> Ext2FS::get_inode_allocation_state(InodeIndex index) const
-{
-    MutexLocker locker(m_lock);
-    if (index == 0)
-        return EINVAL;
-    auto group_index = group_index_from_inode(index);
-    auto const& bgd = group_descriptor(group_index);
-    unsigned index_in_group = index.value() - ((group_index.value() - 1) * inodes_per_group());
-    unsigned bit_index = (index_in_group - 1) % inodes_per_group();
-
-    auto* cached_bitmap = TRY(const_cast<Ext2FS&>(*this).get_bitmap_block(bgd.bg_inode_bitmap));
-    return cached_bitmap->bitmap(inodes_per_group()).get(bit_index);
-}
-
-ErrorOr<void> Ext2FS::update_bitmap_block(BlockIndex bitmap_block, size_t bit_index, bool new_state, u32& super_block_counter, u16& group_descriptor_counter)
-{
-    auto* cached_bitmap = TRY(get_bitmap_block(bitmap_block));
-    bool current_state = cached_bitmap->bitmap(blocks_per_group()).get(bit_index);
-    if (current_state == new_state) {
-        dbgln("Ext2FS: Bit {} in bitmap block {} had unexpected state {}", bit_index, bitmap_block, current_state);
-        return EIO;
-    }
-    cached_bitmap->bitmap(blocks_per_group()).set(bit_index, new_state);
-    cached_bitmap->dirty = true;
-
-    if (new_state) {
-        --super_block_counter;
-        --group_descriptor_counter;
-    } else {
-        ++super_block_counter;
-        ++group_descriptor_counter;
-    }
-
-    m_super_block_dirty = true;
-    m_block_group_descriptors_dirty = true;
-    return {};
-}
-
-ErrorOr<void> Ext2FS::set_inode_allocation_state(InodeIndex inode_index, bool new_state)
-{
-    MutexLocker locker(m_lock);
-    auto group_index = group_index_from_inode(inode_index);
-    unsigned index_in_group = inode_index.value() - ((group_index.value() - 1) * inodes_per_group());
-    unsigned bit_index = (index_in_group - 1) % inodes_per_group();
-
-    dbgln_if(EXT2_DEBUG, "Ext2FS: set_inode_allocation_state: Inode {} -> {}", inode_index, new_state);
-    auto& bgd = const_cast<ext2_group_desc&>(group_descriptor(group_index));
-    return update_bitmap_block(bgd.bg_inode_bitmap, bit_index, new_state, m_super_block.s_free_inodes_count, bgd.bg_free_inodes_count);
-}
-
-Ext2FS::BlockIndex Ext2FS::first_block_index() const
-{
-    return block_size() == 1024 ? 1 : 0;
-}
-
-ErrorOr<Ext2FS::CachedBitmap*> Ext2FS::get_bitmap_block(BlockIndex bitmap_block_index)
-{
-    for (auto& cached_bitmap : m_cached_bitmaps) {
-        if (cached_bitmap->bitmap_block_index == bitmap_block_index)
-            return cached_bitmap.ptr();
-    }
-
-    auto block = TRY(KBuffer::try_create_with_size("Ext2FS: Cached bitmap block"sv, block_size(), Memory::Region::Access::ReadWrite));
-    auto buffer = UserOrKernelBuffer::for_kernel_buffer(block->data());
-    TRY(read_block(bitmap_block_index, &buffer, block_size()));
-    auto new_bitmap = TRY(adopt_nonnull_own_or_enomem(new (nothrow) CachedBitmap(bitmap_block_index, move(block))));
-    TRY(m_cached_bitmaps.try_append(move(new_bitmap)));
-    return m_cached_bitmaps.last().ptr();
-}
-
-ErrorOr<void> Ext2FS::set_block_allocation_state(BlockIndex block_index, bool new_state)
-{
-    VERIFY(block_index != 0);
-    MutexLocker locker(m_lock);
-
-    auto group_index = group_index_from_block_index(block_index);
-    unsigned index_in_group = (block_index.value() - first_block_index().value()) - ((group_index.value() - 1) * blocks_per_group());
-    unsigned bit_index = index_in_group % blocks_per_group();
-    auto& bgd = const_cast<ext2_group_desc&>(group_descriptor(group_index));
-
-    dbgln_if(EXT2_DEBUG, "Ext2FS: Block {} state -> {} (in bitmap block {})", block_index, new_state, bgd.bg_block_bitmap);
-    return update_bitmap_block(bgd.bg_block_bitmap, bit_index, new_state, m_super_block.s_free_blocks_count, bgd.bg_free_blocks_count);
-}
-
-ErrorOr<NonnullLockRefPtr<Inode>> Ext2FS::create_directory(Ext2FSInode& parent_inode, StringView name, mode_t mode, UserID uid, GroupID gid)
-{
-    MutexLocker locker(m_lock);
-    VERIFY(is_directory(mode));
-
-    auto inode = TRY(create_inode(parent_inode, name, mode, 0, uid, gid));
-
-    dbgln_if(EXT2_DEBUG, "Ext2FS: create_directory: created new directory named '{} with inode {}", name, inode->index());
-
-    Vector<Ext2FSDirectoryEntry> entries;
-    auto current_directory_name = TRY(KString::try_create("."sv));
-    TRY(entries.try_empend(move(current_directory_name), inode->index(), static_cast<u8>(EXT2_FT_DIR)));
-    auto parent_directory_name = TRY(KString::try_create(".."sv));
-    TRY(entries.try_empend(move(parent_directory_name), parent_inode.index(), static_cast<u8>(EXT2_FT_DIR)));
-
-    TRY(static_cast<Ext2FSInode&>(*inode).write_directory(entries));
-    TRY(parent_inode.increment_link_count());
-
-    auto& bgd = const_cast<ext2_group_desc&>(group_descriptor(group_index_from_inode(inode->identifier().index())));
-    ++bgd.bg_used_dirs_count;
-    m_block_group_descriptors_dirty = true;
-
-    return inode;
-}
-
-ErrorOr<NonnullLockRefPtr<Inode>> Ext2FS::create_inode(Ext2FSInode& parent_inode, StringView name, mode_t mode, dev_t dev, UserID uid, GroupID gid)
-{
-    if (name.length() > EXT2_NAME_LEN)
-        return ENAMETOOLONG;
-
-    if (parent_inode.m_raw_inode.i_links_count == 0)
-        return ENOENT;
-
-    ext2_inode e2inode {};
-    auto now = kgettimeofday().to_truncated_seconds();
-    e2inode.i_mode = mode;
-    e2inode.i_uid = uid.value();
-    e2inode.i_gid = gid.value();
-    e2inode.i_size = 0;
-    e2inode.i_atime = now;
-    e2inode.i_ctime = now;
-    e2inode.i_mtime = now;
-    e2inode.i_dtime = 0;
-    e2inode.i_flags = 0;
-
-    // For directories, add +1 link count for the "." entry in self.
-    e2inode.i_links_count = is_directory(mode);
-
-    if (is_character_device(mode))
-        e2inode.i_block[0] = dev;
-    else if (is_block_device(mode))
-        e2inode.i_block[1] = dev;
-
-    auto inode_id = TRY(allocate_inode());
-
-    dbgln_if(EXT2_DEBUG, "Ext2FS: writing initial metadata for inode {}", inode_id.value());
-    TRY(write_ext2_inode(inode_id, e2inode));
-
-    auto new_inode = TRY(get_inode({ fsid(), inode_id }));
-
-    dbgln_if(EXT2_DEBUG, "Ext2FS: Adding inode '{}' (mode {:o}) to parent directory {}", name, mode, parent_inode.index());
-    TRY(parent_inode.add_child(*new_inode, name, mode));
-    return new_inode;
-}
-
 ErrorOr<void> Ext2FSInode::populate_lookup_cache()
 {
     VERIFY(m_inode_lock.is_exclusively_locked_by_current_thread());
@@ -1632,12 +982,6 @@ ErrorOr<void> Ext2FSInode::decrement_link_count()
     return {};
 }
 
-void Ext2FS::uncache_inode(InodeIndex index)
-{
-    MutexLocker locker(m_lock);
-    m_inode_cache.remove(index);
-}
-
 ErrorOr<void> Ext2FSInode::chmod(mode_t mode)
 {
     MutexLocker locker(m_inode_lock);
@@ -1682,41 +1026,4 @@ ErrorOr<int> Ext2FSInode::get_block_address(int index)
     return m_block_list[index].value();
 }
 
-unsigned Ext2FS::total_block_count() const
-{
-    MutexLocker locker(m_lock);
-    return super_block().s_blocks_count;
-}
-
-unsigned Ext2FS::free_block_count() const
-{
-    MutexLocker locker(m_lock);
-    return super_block().s_free_blocks_count;
-}
-
-unsigned Ext2FS::total_inode_count() const
-{
-    MutexLocker locker(m_lock);
-    return super_block().s_inodes_count;
-}
-
-unsigned Ext2FS::free_inode_count() const
-{
-    MutexLocker locker(m_lock);
-    return super_block().s_free_inodes_count;
-}
-
-ErrorOr<void> Ext2FS::prepare_to_clear_last_mount()
-{
-    MutexLocker locker(m_lock);
-    for (auto& it : m_inode_cache) {
-        if (it.value->ref_count() > 1)
-            return EBUSY;
-    }
-
-    BlockBasedFileSystem::remove_disk_cache_before_last_unmount();
-    m_inode_cache.clear();
-    m_root_inode = nullptr;
-    return {};
-}
 }
diff --git a/Kernel/FileSystem/Ext2FS/Inode.h b/Kernel/FileSystem/Ext2FS/Inode.h
new file mode 100644
index 0000000000..c4c0d67801
--- /dev/null
+++ b/Kernel/FileSystem/Ext2FS/Inode.h
@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/HashMap.h>
+#include <Kernel/FileSystem/Ext2FS/Definitions.h>
+#include <Kernel/FileSystem/Ext2FS/DirectoryEntry.h>
+#include <Kernel/FileSystem/Ext2FS/FileSystem.h>
+#include <Kernel/FileSystem/Inode.h>
+#include <Kernel/UnixTypes.h>
+
+namespace Kernel {
+
+class Ext2FSInode final : public Inode {
+    friend class Ext2FS;
+
+public:
+    virtual ~Ext2FSInode() override;
+
+    u64 size() const;
+    bool is_symlink() const { return Kernel::is_symlink(m_raw_inode.i_mode); }
+    bool is_directory() const { return Kernel::is_directory(m_raw_inode.i_mode); }
+
+private:
+    // ^Inode
+    virtual ErrorOr<size_t> read_bytes_locked(off_t, size_t, UserOrKernelBuffer& buffer, OpenFileDescription*) const override;
+    virtual InodeMetadata metadata() const override;
+    virtual ErrorOr<void> traverse_as_directory(Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)>) const override;
+    virtual ErrorOr<NonnullLockRefPtr<Inode>> lookup(StringView name) override;
+    virtual ErrorOr<void> flush_metadata() override;
+    virtual ErrorOr<size_t> write_bytes_locked(off_t, size_t, UserOrKernelBuffer const& data, OpenFileDescription*) override;
+    virtual ErrorOr<NonnullLockRefPtr<Inode>> create_child(StringView name, mode_t, dev_t, UserID, GroupID) override;
+    virtual ErrorOr<void> add_child(Inode& child, StringView name, mode_t) override;
+    virtual ErrorOr<void> remove_child(StringView name) override;
+    virtual ErrorOr<void> update_timestamps(Optional<time_t> atime, Optional<time_t> ctime, Optional<time_t> mtime) override;
+    virtual ErrorOr<void> increment_link_count() override;
+    virtual ErrorOr<void> decrement_link_count() override;
+    virtual ErrorOr<void> chmod(mode_t) override;
+    virtual ErrorOr<void> chown(UserID, GroupID) override;
+    virtual ErrorOr<void> truncate(u64) override;
+    virtual ErrorOr<int> get_block_address(int) override;
+
+    ErrorOr<void> write_directory(Vector<Ext2FSDirectoryEntry>&);
+    ErrorOr<void> populate_lookup_cache();
+    ErrorOr<void> resize(u64);
+    ErrorOr<void> write_indirect_block(BlockBasedFileSystem::BlockIndex, Span<BlockBasedFileSystem::BlockIndex>);
+    ErrorOr<void> grow_doubly_indirect_block(BlockBasedFileSystem::BlockIndex, size_t, Span<BlockBasedFileSystem::BlockIndex>, Vector<BlockBasedFileSystem::BlockIndex>&, unsigned&);
+    ErrorOr<void> shrink_doubly_indirect_block(BlockBasedFileSystem::BlockIndex, size_t, size_t, unsigned&);
+    ErrorOr<void> grow_triply_indirect_block(BlockBasedFileSystem::BlockIndex, size_t, Span<BlockBasedFileSystem::BlockIndex>, Vector<BlockBasedFileSystem::BlockIndex>&, unsigned&);
+    ErrorOr<void> shrink_triply_indirect_block(BlockBasedFileSystem::BlockIndex, size_t, size_t, unsigned&);
+    ErrorOr<void> flush_block_list();
+
+    ErrorOr<void> compute_block_list_with_exclusive_locking();
+    ErrorOr<Vector<BlockBasedFileSystem::BlockIndex>> compute_block_list() const;
+    ErrorOr<Vector<BlockBasedFileSystem::BlockIndex>> compute_block_list_with_meta_blocks() const;
+    ErrorOr<Vector<BlockBasedFileSystem::BlockIndex>> compute_block_list_impl(bool include_block_list_blocks) const;
+    ErrorOr<Vector<BlockBasedFileSystem::BlockIndex>> compute_block_list_impl_internal(ext2_inode const&, bool include_block_list_blocks) const;
+
+    Ext2FS& fs();
+    Ext2FS const& fs() const;
+    Ext2FSInode(Ext2FS&, InodeIndex);
+
+    Vector<BlockBasedFileSystem::BlockIndex> m_block_list;
+    HashMap<NonnullOwnPtr<KString>, InodeIndex> m_lookup_cache;
+    ext2_inode m_raw_inode {};
+
+    Mutex m_block_list_lock { "BlockList"sv };
+};
+
+inline Ext2FS& Ext2FSInode::fs()
+{
+    return static_cast<Ext2FS&>(Inode::fs());
+}
+
+inline Ext2FS const& Ext2FSInode::fs() const
+{
+    return static_cast<Ext2FS const&>(Inode::fs());
+}
+
+}
diff --git a/Kernel/FileSystem/ext2_types.h b/Kernel/FileSystem/Ext2FS/ext2_types.h
index 420e6236fb..420e6236fb 100644
--- a/Kernel/FileSystem/ext2_types.h
+++ b/Kernel/FileSystem/Ext2FS/ext2_types.h
diff --git a/Kernel/Storage/StorageManagement.cpp b/Kernel/Storage/StorageManagement.cpp
index 49f2d0b323..3040571203 100644
--- a/Kernel/Storage/StorageManagement.cpp
+++ b/Kernel/Storage/StorageManagement.cpp
@@ -20,7 +20,7 @@
 #include <Kernel/CommandLine.h>
 #include <Kernel/Devices/BlockDevice.h>
 #include <Kernel/Devices/DeviceManagement.h>
-#include <Kernel/FileSystem/Ext2FileSystem.h>
+#include <Kernel/FileSystem/Ext2FS/FileSystem.h>
 #include <Kernel/FileSystem/VirtualFileSystem.h>
 #include <Kernel/Panic.h>
 #include <Kernel/Storage/ATA/AHCI/Controller.h>
diff --git a/Kernel/Syscalls/mount.cpp b/Kernel/Syscalls/mount.cpp
index 4d1d9e503e..037b027b84 100644
--- a/Kernel/Syscalls/mount.cpp
+++ b/Kernel/Syscalls/mount.cpp
@@ -6,7 +6,7 @@
 
 #include <Kernel/FileSystem/Custody.h>
 #include <Kernel/FileSystem/DevPtsFS/FileSystem.h>
-#include <Kernel/FileSystem/Ext2FileSystem.h>
+#include <Kernel/FileSystem/Ext2FS/FileSystem.h>
 #include <Kernel/FileSystem/FATFS/FileSystem.h>
 #include <Kernel/FileSystem/ISO9660FS/FileSystem.h>
 #include <Kernel/FileSystem/Plan9FS/FileSystem.h>