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serenity/Kernel/FileSystem/Ext2FS/FileSystem.cpp
implicitfield 06d4672564 Kernel/Ext2FS: Store the block list as a HashMap rather than a Vector 
Since we now only store blocks that are actually allocated, it is
entirely valid for the block list to be empty, so this commit lifts the
restrictions on accessing inodes with an empty block list.
2024-06-29 19:16:08 +02:00

782 lines
30 KiB
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/*
* 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 <AK/IntegralMath.h>
#include <Kernel/Debug.h>
#include <Kernel/FileSystem/Ext2FS/FileSystem.h>
#include <Kernel/FileSystem/Ext2FS/Inode.h>
#include <Kernel/Tasks/Process.h>
#include <Kernel/UnixTypes.h>
namespace Kernel {
ErrorOr<NonnullRefPtr<FileSystem>> Ext2FS::try_create(OpenFileDescription& file_description, ReadonlyBytes)
{
return TRY(adopt_nonnull_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);
auto super_block_buffer = UserOrKernelBuffer::for_kernel_buffer((u8*)&m_super_block);
auto const superblock_physical_block_count = (sizeof(ext2_super_block) / device_block_size());
// FIXME: We currently have no ability of writing within a device block, but the ability to do so would allow us to use device block sizes larger than 1024.
VERIFY((sizeof(ext2_super_block) % device_block_size()) == 0);
// First superblock is always at offset 1024 (physical block index 2).
TRY(raw_write_blocks(1024 / device_block_size(), superblock_physical_block_count, super_block_buffer));
auto is_sparse = has_flag(get_features_readonly(), FeaturesReadOnly::SparseSuperblock);
for (auto group = 1u; group < m_block_group_count; ++group) {
auto first_block_in_group = first_block_of_group(group);
// Superblock copies with sparse layout are in group number 2 and powers of 3, 5, and 7.
if (!is_sparse || group == 2 || AK::is_power_of<3>(group - 1) || AK::is_power_of<5>(group - 1) || AK::is_power_of<7>(group - 1)) {
dbgln_if(EXT2_DEBUG, "Writing superblock backup to block group {} (block {})", group, first_block_in_group);
TRY(write_blocks(first_block_in_group, 1, super_block_buffer));
}
}
return {};
}
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) % device_block_size()) == 0);
auto super_block_buffer = UserOrKernelBuffer::for_kernel_buffer((u8*)&m_super_block);
TRY(raw_read_blocks(1024 / device_block_size(), (sizeof(ext2_super_block) / device_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 (super_block.s_state == EXT2_ERROR_FS)
dmesgln("Ext2FS: Was not unmounted cleanly, file system may be erroneous!");
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_logical_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(logical_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), logical_block_size());
BlockIndex first_block_of_bgdt = first_block_of_block_group_descriptors();
m_cached_group_descriptor_table = TRY(KBuffer::try_create_with_size("Ext2FS: Block group descriptors"sv, logical_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());
// Set filesystem to "error" state until we unmount cleanly.
dmesgln("Ext2FS: Mount successful, setting superblock to error state.");
m_super_block.s_state = EXT2_ERROR_FS;
TRY(flush_super_block());
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 & (logical_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::FeaturesOptional Ext2FS::get_features_optional() const
{
if (m_super_block.s_rev_level > 0)
return static_cast<Ext2FS::FeaturesOptional>(m_super_block.s_feature_compat);
return Ext2FS::FeaturesOptional::None;
}
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 = first_block_of_group(group_index);
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() - first_block_index().value()) / blocks_per_group() + 1;
}
Ext2FS::BlockIndex Ext2FS::first_block_of_group(GroupIndex group_index) const
{
return (group_index.value() - 1) * blocks_per_group() + first_block_index().value();
}
Ext2FS::BlockIndex Ext2FS::first_block_of_block_group_descriptors() const
{
return logical_block_size() == 1024 ? 2 : 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 logical_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, logical_block_size(), Memory::Region::Access::ReadWrite));
auto buffer = UserOrKernelBuffer::for_kernel_buffer(block->data());
TRY(read_block(bitmap_block_index, &buffer, logical_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<NonnullRefPtr<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<NonnullRefPtr<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().truncated_seconds_since_epoch();
e2inode.i_mode = mode;
e2inode.i_uid = static_cast<u16>(uid.value());
ext2fs_set_i_uid_high(e2inode, uid.value() >> 16);
e2inode.i_gid = static_cast<u16>(gid.value());
ext2fs_set_i_gid_high(e2inode, gid.value() >> 16);
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(Inode& mount_guest_inode)
{
MutexLocker locker(m_lock);
bool any_inode_busy = false;
for (auto& it : m_inode_cache) {
// We hold the last reference to the root inode, and the VFS Mount object holds the last reference to the mount_guest_inode,
// so they are allowed to have one more reference.
if ((it.value == m_root_inode || it.value->identifier() == mount_guest_inode.identifier()) && it.value->ref_count() > 2) {
dbgln_if(EXT2_DEBUG, "Ext2FS: Ignoring root or mount point inode's last reference");
continue;
}
// The Inode::all_instances list always holds one reference to all inodes, which we disregard.
if (it.value->ref_count() > 1) {
dbgln_if(EXT2_DEBUG, "Ext2FS: Busy inode {} ({} refs)", it.value->index(), it.value->ref_count());
any_inode_busy = true;
}
}
if (any_inode_busy)
return EBUSY;
m_inode_cache.clear();
m_root_inode = nullptr;
// Mark filesystem as valid before unmount.
dmesgln("Ext2FS: Clean unmount, setting superblock to valid state");
m_super_block.s_state = EXT2_VALID_FS;
TRY(flush_super_block());
BlockBasedFileSystem::remove_disk_cache_before_last_unmount();
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 const& [_, block_index] : blocks) {
VERIFY(block_index <= super_block().s_blocks_count && block_index != 0);
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().truncated_seconds_since_epoch();
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), logical_block_size());
auto first_block_of_bgdt = first_block_of_block_group_descriptors();
auto buffer = UserOrKernelBuffer::for_kernel_buffer((u8*)block_group_descriptors());
auto write_bgdt_to_block = [&](BlockIndex index) {
if (auto result = write_blocks(index, blocks_to_write, buffer); result.is_error())
dbgln("Ext2FS[{}]::flush_block_group_descriptor_table(): Failed to write blocks: {}", fsid(), result.error());
};
write_bgdt_to_block(first_block_of_bgdt);
auto is_sparse = has_flag(get_features_readonly(), FeaturesReadOnly::SparseSuperblock);
for (auto group = 1u; group < m_block_group_count; ++group) {
// First block is occupied by the super block
BlockIndex second_block_in_group = first_block_of_group(group).value() + 1;
// BGDT copies with sparse layout are in group number 2 and powers of 3, 5, and 7.
if (!is_sparse || group == 2 || AK::is_power_of<3>(group - 1) || AK::is_power_of<5>(group - 1) || AK::is_power_of<7>(group - 1)) {
dbgln_if(EXT2_DEBUG, "Writing block group descriptor table backup to block group {} (block {})", group, second_block_in_group);
write_bgdt_to_block(second_block_in_group);
}
}
}
ErrorOr<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());
return result.release_error();
}
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, logical_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, RefPtr<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();
});
}
auto result = BlockBasedFileSystem::flush_writes();
if (result.is_error()) {
dbgln("Ext2FS[{}]::flush_writes(): Failed to flush writes: {}", BlockBasedFileSystem::fsid(), result.error());
return result.release_error();
}
return {};
}
ErrorOr<NonnullRefPtr<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_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<NonnullRefPtr<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 NonnullRefPtr<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_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;
}
}
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