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Kernel: Ext2FS now does allocations better 

We only have to allocate at the beginning of the all functions and
can properly exit before any disk reads if we run out of memory.

This makes development little bit 'harder' since the {read,write}_block
user must allocate a buffer of atleast block_size bytes.

I also made disk access to cause kernel panic on error since the error
handling during file write is something I don't want to think now.
The filesystem can easily corrupt so, I feel like when disk io starts
to fail I'll come back to this.
This commit is contained in:
Bananymous 2023-03-23 23:22:31 +02:00
parent 2152b8b95f
commit 7d2ab53baa
2 changed files with 86 additions and 62 deletions
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4
kernel/include/kernel/FS/Ext2.h
View File

@ -185,8 +185,8 @@ namespace Kernel
BAN::ErrorOr<void> delete_inode(uint32_t);
BAN::ErrorOr<void> resize_inode(uint32_t, size_t);
BAN::ErrorOr<BAN::Vector<uint8_t>> read_block(uint32_t);
BAN::ErrorOr<void> write_block(uint32_t, BAN::Span<const uint8_t>);
void read_block(uint32_t, BAN::Span<uint8_t>);
void write_block(uint32_t, BAN::Span<const uint8_t>);
const Ext2::Superblock& superblock() const { return m_superblock; }

144
kernel/kernel/FS/Ext2.cpp
View File

@ -152,9 +152,12 @@ namespace Kernel
BAN::ErrorOr<BAN::RefPtr<Inode>> Ext2Inode::create(Ext2FS& fs, uint32_t inode_inode, BAN::StringView name)
{
BAN::Vector<uint8_t> block_buffer;
TRY(block_buffer.resize(fs.block_size()));
auto inode_location = TRY(fs.locate_inode(inode_inode));
auto inode_buffer = TRY(fs.read_block(inode_location.block));
auto& inode = *(Ext2::Inode*)(inode_buffer.data() + inode_location.offset);
fs.read_block(inode_location.block, block_buffer.span());
auto& inode = *(Ext2::Inode*)(block_buffer.data() + inode_location.offset);
Ext2Inode* result = new Ext2Inode(fs, inode, name, inode_inode);
if (result == nullptr)
return BAN::Error::from_errno(ENOMEM);
@ -166,8 +169,7 @@ namespace Kernel
uint32_t data_blocks_count = m_inode.blocks / (2 << m_fs.superblock().log_block_size);
uint32_t blocks_per_array = (1024 << m_fs.superblock().log_block_size) / sizeof(uint32_t);
if (asked_data_block >= data_blocks_count)
return BAN::Error::from_c_string("Ext2: no such block");
ASSERT(asked_data_block < data_blocks_count);
// Direct block
if (asked_data_block < 12)
@ -180,13 +182,17 @@ namespace Kernel
asked_data_block -= 12;
uint32_t block_size = m_fs.block_size();
BAN::Vector<uint8_t> block_buffer;
TRY(block_buffer.resize(block_size));
// Singly indirect block
if (asked_data_block < blocks_per_array)
{
if (m_inode.block[12] == 0)
return BAN::Error::from_errno(EIO);
auto block_array = TRY(m_fs.read_block(m_inode.block[12]));
uint32_t block = ((uint32_t*)block_array.data())[asked_data_block];
m_fs.read_block(m_inode.block[12], block_buffer.span()); // Block array
uint32_t block = ((uint32_t*)block_buffer.data())[asked_data_block];
if (block == 0)
return BAN::Error::from_errno(EIO);
return block;
@ -197,12 +203,12 @@ namespace Kernel
// Doubly indirect blocks
if (asked_data_block < blocks_per_array * blocks_per_array)
{
auto singly_indirect_array = TRY(m_fs.read_block(m_inode.block[13]));
uint32_t direct_block = ((uint32_t*)singly_indirect_array.data())[asked_data_block / blocks_per_array];
m_fs.read_block(m_inode.block[13], block_buffer.span()); // Singly indirect array
uint32_t direct_block = ((uint32_t*)block_buffer.data())[asked_data_block / blocks_per_array];
if (direct_block == 0)
return BAN::Error::from_errno(EIO);
auto block_array = TRY(m_fs.read_block(direct_block));
uint32_t block = ((uint32_t*)block_array.data())[asked_data_block % blocks_per_array];
m_fs.read_block(direct_block, block_buffer.span()); // Block array
uint32_t block = ((uint32_t*)block_buffer.data())[asked_data_block % blocks_per_array];
if (block == 0)
return BAN::Error::from_errno(EIO);
return block;
@ -213,16 +219,16 @@ namespace Kernel
// Triply indirect blocks
if (asked_data_block < blocks_per_array * blocks_per_array * blocks_per_array)
{
auto doubly_indirect_array = TRY(m_fs.read_block(m_inode.block[14]));
uint32_t singly_indirect_block = ((uint32_t*)doubly_indirect_array.data())[asked_data_block / (blocks_per_array * blocks_per_array)];
m_fs.read_block(m_inode.block[14], block_buffer.span()); // Doubly indirect array
uint32_t singly_indirect_block = ((uint32_t*)block_buffer.data())[asked_data_block / (blocks_per_array * blocks_per_array)];
if (singly_indirect_block == 0)
return BAN::Error::from_errno(EIO);
auto singly_indirect_array = TRY(m_fs.read_block(singly_indirect_block));
uint32_t direct_block = ((uint32_t*)singly_indirect_array.data())[(asked_data_block / blocks_per_array) % blocks_per_array];
m_fs.read_block(singly_indirect_block, block_buffer.span()); // Singly indirect array
uint32_t direct_block = ((uint32_t*)block_buffer.data())[(asked_data_block / blocks_per_array) % blocks_per_array];
if (direct_block == 0)
return BAN::Error::from_errno(EIO);
auto block_array = TRY(m_fs.read_block(direct_block));
uint32_t block = ((uint32_t*)block_array.data())[asked_data_block % blocks_per_array];
m_fs.read_block(direct_block, block_buffer.span()); // Block array
uint32_t block = ((uint32_t*)block_buffer.data())[asked_data_block % blocks_per_array];
if (block == 0)
return BAN::Error::from_errno(EIO);
return block;
@ -243,7 +249,9 @@ namespace Kernel
if (offset + count > m_inode.size)
count = m_inode.size - offset;
const uint32_t block_size = 1024 << m_fs.superblock().log_block_size;
uint32_t block_size = 1024 << m_fs.superblock().log_block_size;
BAN::Vector<uint8_t> block_buffer;
TRY(block_buffer.resize(block_size));
const uint32_t first_block = offset / block_size;
const uint32_t last_block = BAN::Math::div_round_up<uint32_t>(offset + count, block_size);
@ -253,12 +261,11 @@ namespace Kernel
for (uint32_t block = first_block; block < last_block; block++)
{
uint32_t block_index = TRY(data_block_index(block));
auto block_data = TRY(m_fs.read_block(block_index));
ASSERT(block_data.size() == block_size);
m_fs.read_block(block_index, block_buffer.span());
uint32_t copy_offset = (offset + n_read) % block_size;
uint32_t to_copy = BAN::Math::min<uint32_t>(block_size - copy_offset, count - n_read);
memcpy((uint8_t*)buffer + n_read, block_data.data() + copy_offset, to_copy);
memcpy((uint8_t*)buffer + n_read, block_buffer.data() + copy_offset, to_copy);
n_read += to_copy;
}
@ -274,6 +281,10 @@ namespace Kernel
if (name.size() > 255)
return BAN::Error::from_errno(ENAMETOOLONG);
uint32_t block_size = m_fs.block_size();
BAN::Vector<uint8_t> block_buffer;
TRY(block_buffer.resize(block_size));
auto error_or = directory_find_impl(name);
if (!error_or.is_error())
return BAN::Error::from_errno(EEXISTS);
@ -307,15 +318,15 @@ namespace Kernel
// Insert inode to this directory
uint32_t data_block_count = m_inode.blocks / (2 << m_fs.superblock().log_block_size);
uint32_t block_index = TRY(data_block_index(data_block_count - 1));
auto block_data = TRY(m_fs.read_block(block_index));
m_fs.read_block(block_index, block_buffer.span());
const uint8_t* block_data_end = block_data.data() + block_data.size();
const uint8_t* entry_addr = block_data.data();
const uint8_t* block_buffer_end = block_buffer.data() + block_size;
const uint8_t* entry_addr = block_buffer.data();
uint32_t needed_entry_len = sizeof(Ext2::LinkedDirectoryEntry) + name.size();
bool insered = false;
while (entry_addr < block_data_end)
while (entry_addr < block_buffer_end)
{
auto& entry = *(Ext2::LinkedDirectoryEntry*)entry_addr;
@ -327,12 +338,12 @@ namespace Kernel
auto& new_entry = *(Ext2::LinkedDirectoryEntry*)(entry_addr + entry.rec_len);
new_entry.inode = inode_index;
new_entry.rec_len = block_data_end - (uint8_t*)&new_entry;
new_entry.rec_len = block_buffer_end - (uint8_t*)&new_entry;
new_entry.name_len = name.size();
new_entry.file_type = Ext2::Enum::REG_FILE;
memcpy(new_entry.name, name.data(), name.size());
TRY(m_fs.write_block(block_index, block_data.span()));
m_fs.write_block(block_index, block_buffer.span());
insered = true;
break;
@ -352,17 +363,21 @@ namespace Kernel
if (!ifdir())
return BAN::Error::from_errno(ENOTDIR);
uint32_t block_size = m_fs.block_size();
BAN::Vector<uint8_t> block_buffer;
TRY(block_buffer.resize(block_size));
uint32_t data_block_count = m_inode.blocks / (2 << m_fs.superblock().log_block_size);
for (uint32_t i = 0; i < data_block_count; i++)
{
uint32_t block_index = TRY(data_block_index(i));
auto block_data = TRY(m_fs.read_block(block_index));
m_fs.read_block(block_index, block_buffer.span());
const uint8_t* block_data_end = block_data.data() + block_data.size();
const uint8_t* entry_addr = block_data.data();
const uint8_t* block_buffer_end = block_buffer.data() + block_size;
const uint8_t* entry_addr = block_buffer.data();
while (entry_addr < block_data_end)
while (entry_addr < block_buffer_end)
{
const auto& entry = *(const Ext2::LinkedDirectoryEntry*)entry_addr;
BAN::StringView entry_name(entry.name, entry.name_len);
@ -380,6 +395,10 @@ namespace Kernel
if (!ifdir())
return BAN::Error::from_errno(ENOTDIR);
uint32_t block_size = m_fs.block_size();
BAN::Vector<uint8_t> block_buffer;
TRY(block_buffer.resize(block_size));
uint32_t data_block_count = m_inode.blocks / (2 << m_fs.superblock().log_block_size);
BAN::Vector<BAN::RefPtr<Inode>> inodes;
@ -387,11 +406,11 @@ namespace Kernel
for (uint32_t i = 0; i < data_block_count; i++)
{
uint32_t block_index = TRY(data_block_index(i));
auto block_data = TRY(m_fs.read_block(block_index));
m_fs.read_block(block_index, block_buffer.span());
const uint8_t* block_data_end = block_data.data() + block_data.size();
const uint8_t* entry_addr = block_data.data();
while (entry_addr < block_data_end)
const uint8_t* block_buffer_end = block_buffer.data() + block_size;
const uint8_t* entry_addr = block_buffer.data();
while (entry_addr < block_buffer_end)
{
const auto& entry = *(const Ext2::LinkedDirectoryEntry*)entry_addr;
if (entry.inode)
@ -496,17 +515,23 @@ namespace Kernel
{
ASSERT(ext2_inode.size == 0);
uint32_t block_size = this->block_size();
BAN::Vector<uint8_t> bgd_buffer;
TRY(bgd_buffer.resize(block_size));
BAN::Vector<uint8_t> inode_bitmap;
TRY(inode_bitmap.resize(block_size));
uint32_t number_of_block_groups = BAN::Math::div_round_up(superblock().inodes_count, superblock().inodes_per_group);
for (uint32_t group = 0; group < number_of_block_groups; group++)
{
auto bgd_location = this->locate_block_group_descriptior(group);
auto bgd_buffer = TRY(this->read_block(bgd_location.block));
auto bgd_location = locate_block_group_descriptior(group);
read_block(bgd_location.block, bgd_buffer.span());
auto& bgd = *(Ext2::BlockGroupDescriptor*)(bgd_buffer.data() + bgd_location.offset);
if (bgd.free_inodes_count == 0)
continue;
auto inode_bitmap = TRY(read_block(bgd.inode_bitmap));
read_block(bgd.inode_bitmap, inode_bitmap.span());
for (uint32_t inode_offset = 0; inode_offset < superblock().inodes_per_group; inode_offset++)
{
uint32_t byte = inode_offset / 8;
@ -514,10 +539,10 @@ namespace Kernel
if ((inode_bitmap[byte] & (1 << bit)) == 0)
{
inode_bitmap[byte] |= (1 << bit);
TRY(write_block(bgd.inode_bitmap, inode_bitmap.span()));
write_block(bgd.inode_bitmap, inode_bitmap.span());
bgd.free_inodes_count--;
TRY(write_block(bgd_location.block, bgd_buffer.span()));
write_block(bgd_location.block, bgd_buffer.span());
return group * superblock().inodes_per_group + inode_offset + 1;
}
@ -527,37 +552,34 @@ namespace Kernel
return BAN::Error::from_c_string("No free inodes available in the whole filesystem");
}
BAN::ErrorOr<BAN::Vector<uint8_t>> Ext2FS::read_block(uint32_t block)
void Ext2FS::read_block(uint32_t block, BAN::Span<uint8_t> buffer)
{
uint32_t sector_size = m_partition.device().sector_size();
uint32_t block_size = this->block_size();
uint32_t sectors_per_block = block_size / sector_size;
BAN::Vector<uint8_t> block_buffer;
TRY(block_buffer.resize(block_size));
TRY(m_partition.read_sectors(block * sectors_per_block, sectors_per_block, block_buffer.data()));
return block_buffer;
ASSERT(buffer.size() >= block_size);
MUST(m_partition.read_sectors(block * sectors_per_block, sectors_per_block, buffer.data()));
}
BAN::ErrorOr<void> Ext2FS::write_block(uint32_t block, BAN::Span<const uint8_t> data)
void Ext2FS::write_block(uint32_t block, BAN::Span<const uint8_t> data)
{
uint32_t sector_size = m_partition.device().sector_size();
uint32_t block_size = this->block_size();
uint32_t sectors_per_block = block_size / sector_size;
ASSERT(data.size() <= block_size);
TRY(m_partition.write_sectors(block * sectors_per_block, sectors_per_block, data.data()));
return {};
MUST(m_partition.write_sectors(block * sectors_per_block, sectors_per_block, data.data()));
}
BAN::ErrorOr<Ext2FS::BlockLocation> Ext2FS::locate_inode(uint32_t inode_index)
{
if (inode_index >= superblock().inodes_count)
return BAN::Error::from_format("Asked to read inode {}, but only {} exist in the filesystem", inode_index, superblock().inodes_count);
ASSERT(inode_index < superblock().inodes_count);
uint32_t block_size = this->block_size();
BAN::Vector<uint8_t> bgd_buffer;
TRY(bgd_buffer.resize(block_size));
uint32_t inode_block_group = (inode_index - 1) / superblock().inodes_per_group;
uint32_t local_inode_index = (inode_index - 1) % superblock().inodes_per_group;
@ -565,20 +587,22 @@ namespace Kernel
uint32_t inode_table_byte_offset = (local_inode_index * superblock().inode_size);
auto bgd_location = locate_block_group_descriptior(inode_block_group);
auto bgd_buffer = TRY(read_block(bgd_location.block));
read_block(bgd_location.block, bgd_buffer.span());
auto& bgd = *(Ext2::BlockGroupDescriptor*)(bgd_buffer.data() + bgd_location.offset);
#if VERIFY_INODE_EXISTANCE
ASSERT(superblock().inodes_per_group <= block_size * 8);
auto inode_bitmap = TRY(read_block(bgd.inode_bitmap));
uint32_t byte = local_inode_index / 8;
uint32_t bit = local_inode_index % 8;
ASSERT(inode_bitmap[byte] & (1 << bit));
#endif
BlockLocation location;
location.block = bgd.inode_table + inode_table_byte_offset / block_size;
location.offset = inode_table_byte_offset % block_size;
#if VERIFY_INODE_EXISTANCE
// Note we reuse the bgd_buffer since it is not needed anymore
ASSERT(superblock().inodes_per_group <= block_size * 8);
read_block(bgd.inode_bitmap, bgd_buffer.span());
uint32_t byte = local_inode_index / 8;
uint32_t bit = local_inode_index % 8;
ASSERT(bgd_buffer[byte] & (1 << bit));
#endif
return location;
}