forked from Bananymous/banan-os
Kernel: Rewrite DiskCache
We now cache only clean pages since I don't want to think about syncing the disk later.
This commit is contained in:
parent
2f52001c6d
commit
104894c0c7
|
@ -7,16 +7,14 @@
|
|||
namespace Kernel
|
||||
{
|
||||
|
||||
class StorageDevice;
|
||||
|
||||
class DiskCache
|
||||
{
|
||||
public:
|
||||
DiskCache(StorageDevice&);
|
||||
DiskCache(size_t sector_size);
|
||||
~DiskCache();
|
||||
|
||||
BAN::ErrorOr<void> read_sector(uint64_t sector, uint8_t* buffer);
|
||||
BAN::ErrorOr<void> write_sector(uint64_t sector, const uint8_t* buffer);
|
||||
bool read_from_cache(uint64_t sector, uint8_t* buffer);
|
||||
BAN::ErrorOr<void> write_to_cache(uint64_t sector, const uint8_t* buffer, bool dirty);
|
||||
|
||||
void sync();
|
||||
size_t release_clean_pages(size_t);
|
||||
|
@ -30,15 +28,10 @@ namespace Kernel
|
|||
uint64_t first_sector { 0 };
|
||||
uint8_t sector_mask { 0 };
|
||||
uint8_t dirty_mask { 0 };
|
||||
|
||||
void sync(StorageDevice&);
|
||||
BAN::ErrorOr<void> read_sector(StorageDevice&, uint64_t sector, uint8_t* buffer);
|
||||
BAN::ErrorOr<void> write_sector(StorageDevice&, uint64_t sector, const uint8_t* buffer);
|
||||
};
|
||||
|
||||
private:
|
||||
SpinLock m_lock;
|
||||
StorageDevice& m_device;
|
||||
const size_t m_sector_size;
|
||||
BAN::Vector<PageCache> m_cache;
|
||||
};
|
||||
|
||||
|
|
|
@ -81,7 +81,7 @@ namespace Kernel
|
|||
void add_disk_cache();
|
||||
|
||||
private:
|
||||
DiskCache* m_disk_cache { nullptr };
|
||||
BAN::Optional<DiskCache> m_disk_cache;
|
||||
BAN::Vector<Partition*> m_partitions;
|
||||
|
||||
friend class DiskCache;
|
||||
|
|
|
@ -8,105 +8,121 @@
|
|||
namespace Kernel
|
||||
{
|
||||
|
||||
DiskCache::DiskCache(StorageDevice& device)
|
||||
: m_device(device)
|
||||
{ }
|
||||
DiskCache::DiskCache(size_t sector_size)
|
||||
: m_sector_size(sector_size)
|
||||
{
|
||||
ASSERT(PAGE_SIZE % m_sector_size == 0);
|
||||
ASSERT(PAGE_SIZE / m_sector_size <= sizeof(PageCache::sector_mask) * 8);
|
||||
ASSERT(PAGE_SIZE / m_sector_size <= sizeof(PageCache::dirty_mask) * 8);
|
||||
}
|
||||
|
||||
DiskCache::~DiskCache()
|
||||
{
|
||||
release_all_pages();
|
||||
}
|
||||
|
||||
BAN::ErrorOr<void> DiskCache::read_sector(uint64_t sector, uint8_t* buffer)
|
||||
bool DiskCache::read_from_cache(uint64_t sector, uint8_t* buffer)
|
||||
{
|
||||
ASSERT(m_device.sector_size() <= PAGE_SIZE);
|
||||
uint64_t sectors_per_page = PAGE_SIZE / m_sector_size;
|
||||
uint64_t page_cache_offset = sector % sectors_per_page;
|
||||
uint64_t page_cache_start = sector - page_cache_offset;
|
||||
|
||||
LockGuard _(m_lock);
|
||||
PageTable& page_table = PageTable::current();
|
||||
LockGuard page_table_locker(page_table);
|
||||
ASSERT(page_table.is_page_free(0));
|
||||
|
||||
uint64_t sectors_per_page = PAGE_SIZE / m_device.sector_size();
|
||||
ASSERT(sectors_per_page <= sizeof(PageCache::sector_mask) * 8);
|
||||
CriticalScope _;
|
||||
for (auto& cache : m_cache)
|
||||
{
|
||||
if (cache.first_sector < page_cache_start)
|
||||
continue;
|
||||
if (cache.first_sector > page_cache_start)
|
||||
break;
|
||||
|
||||
uint64_t page_cache_start = sector / sectors_per_page * sectors_per_page;
|
||||
if (!(cache.sector_mask & (1 << page_cache_offset)))
|
||||
continue;
|
||||
|
||||
page_table.map_page_at(cache.paddr, 0, PageTable::Flags::Present);
|
||||
memcpy(buffer, (void*)(page_cache_offset * m_sector_size), m_sector_size);
|
||||
page_table.unmap_page(0);
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
return false;
|
||||
};
|
||||
|
||||
BAN::ErrorOr<void> DiskCache::write_to_cache(uint64_t sector, const uint8_t* buffer, bool dirty)
|
||||
{
|
||||
uint64_t sectors_per_page = PAGE_SIZE / m_sector_size;
|
||||
uint64_t page_cache_offset = sector % sectors_per_page;
|
||||
uint64_t page_cache_start = sector - page_cache_offset;
|
||||
|
||||
PageTable& page_table = PageTable::current();
|
||||
LockGuard page_table_locker(page_table);
|
||||
ASSERT(page_table.is_page_free(0));
|
||||
|
||||
CriticalScope _;
|
||||
|
||||
// Check if we already have a cache for this page
|
||||
// FIXME: binary search
|
||||
size_t index = 0;
|
||||
|
||||
// Search the cache if the have this sector in memory
|
||||
for (; index < m_cache.size(); index++)
|
||||
{
|
||||
if (m_cache[index].first_sector < page_cache_start)
|
||||
auto& cache = m_cache[index];
|
||||
|
||||
if (cache.first_sector < page_cache_start)
|
||||
continue;
|
||||
if (m_cache[index].first_sector > page_cache_start)
|
||||
if (cache.first_sector > page_cache_start)
|
||||
break;
|
||||
TRY(m_cache[index].read_sector(m_device, sector, buffer));
|
||||
|
||||
page_table.map_page_at(cache.paddr, 0, PageTable::Flags::ReadWrite | PageTable::Flags::Present);
|
||||
memcpy((void*)(page_cache_offset * m_sector_size), buffer, m_sector_size);
|
||||
page_table.unmap_page(0);
|
||||
|
||||
cache.sector_mask |= 1 << page_cache_offset;
|
||||
if (dirty)
|
||||
cache.dirty_mask |= 1 << page_cache_offset;
|
||||
|
||||
return {};
|
||||
}
|
||||
|
||||
// Try to allocate new cache
|
||||
if (paddr_t paddr = Heap::get().take_free_page())
|
||||
// Try to add new page to the cache
|
||||
paddr_t paddr = Heap::get().take_free_page();
|
||||
if (paddr == 0)
|
||||
return BAN::Error::from_errno(ENOMEM);
|
||||
|
||||
PageCache cache;
|
||||
cache.paddr = paddr;
|
||||
cache.first_sector = page_cache_start;
|
||||
cache.sector_mask = 1 << page_cache_offset;
|
||||
cache.dirty_mask = dirty ? cache.sector_mask : 0;
|
||||
|
||||
if (auto ret = m_cache.insert(index, cache); ret.is_error())
|
||||
{
|
||||
MUST(m_cache.insert(index, { .paddr = paddr, .first_sector = page_cache_start }));
|
||||
TRY(m_cache[index].read_sector(m_device, sector, buffer));
|
||||
return {};
|
||||
Heap::get().release_page(paddr);
|
||||
return ret.error();
|
||||
}
|
||||
|
||||
// Could not allocate new cache, read from disk
|
||||
TRY(m_device.read_sectors_impl(sector, 1, buffer));
|
||||
return {};
|
||||
}
|
||||
page_table.map_page_at(cache.paddr, 0, PageTable::Flags::Present);
|
||||
memcpy((void*)(page_cache_offset * m_sector_size), buffer, m_sector_size);
|
||||
page_table.unmap_page(0);
|
||||
|
||||
BAN::ErrorOr<void> DiskCache::write_sector(uint64_t sector, const uint8_t* buffer)
|
||||
{
|
||||
ASSERT(m_device.sector_size() <= PAGE_SIZE);
|
||||
|
||||
LockGuard _(m_lock);
|
||||
|
||||
uint64_t sectors_per_page = PAGE_SIZE / m_device.sector_size();
|
||||
ASSERT(sectors_per_page <= sizeof(PageCache::sector_mask) * 8);
|
||||
|
||||
uint64_t page_cache_start = sector / sectors_per_page * sectors_per_page;
|
||||
|
||||
// Check if we already have a cache for this page
|
||||
// FIXME: binary search
|
||||
size_t index = 0;
|
||||
for (; index < m_cache.size(); index++)
|
||||
{
|
||||
if (m_cache[index].first_sector < page_cache_start)
|
||||
continue;
|
||||
if (m_cache[index].first_sector > page_cache_start)
|
||||
break;
|
||||
TRY(m_cache[index].write_sector(m_device, sector, buffer));
|
||||
return {};
|
||||
}
|
||||
|
||||
// Try to allocate new cache
|
||||
if (paddr_t paddr = Heap::get().take_free_page())
|
||||
{
|
||||
MUST(m_cache.insert(index, { .paddr = paddr, .first_sector = page_cache_start }));
|
||||
TRY(m_cache[index].write_sector(m_device, sector, buffer));
|
||||
return {};
|
||||
}
|
||||
|
||||
// Could not allocate new cache, write to disk
|
||||
TRY(m_device.write_sectors_impl(sector, 1, buffer));
|
||||
return {};
|
||||
}
|
||||
|
||||
void DiskCache::sync()
|
||||
{
|
||||
ASSERT(m_device.sector_size() <= PAGE_SIZE);
|
||||
|
||||
LockGuard _(m_lock);
|
||||
for (auto& cache_block : m_cache)
|
||||
cache_block.sync(m_device);
|
||||
CriticalScope _;
|
||||
for (auto& cache : m_cache)
|
||||
ASSERT(cache.dirty_mask == 0);
|
||||
}
|
||||
|
||||
size_t DiskCache::release_clean_pages(size_t page_count)
|
||||
{
|
||||
ASSERT(m_device.sector_size() <= PAGE_SIZE);
|
||||
|
||||
// NOTE: There might not actually be page_count pages after this
|
||||
// function returns. The synchronization must be done elsewhere.
|
||||
LockGuard _(m_lock);
|
||||
CriticalScope _;
|
||||
|
||||
size_t released = 0;
|
||||
for (size_t i = 0; i < m_cache.size() && released < page_count;)
|
||||
|
@ -128,138 +144,16 @@ namespace Kernel
|
|||
|
||||
size_t DiskCache::release_pages(size_t page_count)
|
||||
{
|
||||
ASSERT(m_device.sector_size() <= PAGE_SIZE);
|
||||
|
||||
size_t released = release_clean_pages(page_count);
|
||||
if (released >= page_count)
|
||||
return released;
|
||||
|
||||
// NOTE: There might not actually be page_count pages after this
|
||||
// function returns. The synchronization must be done elsewhere.
|
||||
LockGuard _(m_lock);
|
||||
|
||||
while (!m_cache.empty() && released < page_count)
|
||||
{
|
||||
m_cache.back().sync(m_device);
|
||||
Heap::get().release_page(m_cache.back().paddr);
|
||||
m_cache.pop_back();
|
||||
released++;
|
||||
}
|
||||
|
||||
(void)m_cache.shrink_to_fit();
|
||||
|
||||
return released;
|
||||
ASSERT_NOT_REACHED();
|
||||
}
|
||||
|
||||
void DiskCache::release_all_pages()
|
||||
{
|
||||
ASSERT(m_device.sector_size() <= PAGE_SIZE);
|
||||
|
||||
LockGuard _(m_lock);
|
||||
|
||||
for (auto& cache_block : m_cache)
|
||||
{
|
||||
cache_block.sync(m_device);
|
||||
Heap::get().release_page(cache_block.paddr);
|
||||
}
|
||||
|
||||
m_cache.clear();
|
||||
}
|
||||
|
||||
void DiskCache::PageCache::sync(StorageDevice& device)
|
||||
{
|
||||
if (this->dirty_mask == 0)
|
||||
return;
|
||||
|
||||
ASSERT(device.sector_size() <= PAGE_SIZE);
|
||||
|
||||
PageTable& page_table = PageTable::current();
|
||||
|
||||
page_table.lock();
|
||||
ASSERT(page_table.is_page_free(0));
|
||||
|
||||
page_table.map_page_at(this->paddr, 0, PageTable::Flags::ReadWrite | PageTable::Flags::Present);
|
||||
|
||||
for (size_t i = 0; i < PAGE_SIZE / device.sector_size(); i++)
|
||||
{
|
||||
if (!(this->dirty_mask & (1 << i)))
|
||||
continue;
|
||||
MUST(device.write_sectors_impl(this->first_sector + i, 1, (const uint8_t*)(i * device.sector_size())));
|
||||
// FIXME: race condition between here :)
|
||||
this->dirty_mask &= ~(1 << i);
|
||||
}
|
||||
|
||||
page_table.unmap_page(0);
|
||||
|
||||
page_table.unlock();
|
||||
}
|
||||
|
||||
BAN::ErrorOr<void> DiskCache::PageCache::read_sector(StorageDevice& device, uint64_t sector, uint8_t* buffer)
|
||||
{
|
||||
ASSERT(device.sector_size() <= PAGE_SIZE);
|
||||
|
||||
uint64_t sectors_per_page = PAGE_SIZE / device.sector_size();
|
||||
uint64_t sector_offset = sector - this->first_sector;
|
||||
|
||||
ASSERT(sector_offset < sectors_per_page);
|
||||
|
||||
PageTable& page_table = PageTable::current();
|
||||
|
||||
page_table.lock();
|
||||
ASSERT(page_table.is_page_free(0));
|
||||
|
||||
page_table.map_page_at(this->paddr, 0, PageTable::Flags::ReadWrite | PageTable::Flags::Present);
|
||||
|
||||
// Sector not yet cached
|
||||
if (!(this->sector_mask & (1 << sector_offset)))
|
||||
{
|
||||
TRY(device.read_sectors_impl(sector, 1, buffer));
|
||||
|
||||
CriticalScope _;
|
||||
memcpy((void*)(sector_offset * device.sector_size()), buffer, device.sector_size());
|
||||
this->sector_mask |= 1 << sector_offset;
|
||||
}
|
||||
else
|
||||
{
|
||||
CriticalScope _;
|
||||
memcpy(buffer, (const void*)(sector_offset * device.sector_size()), device.sector_size());
|
||||
}
|
||||
|
||||
page_table.unmap_page(0);
|
||||
|
||||
page_table.unlock();
|
||||
|
||||
return {};
|
||||
}
|
||||
|
||||
BAN::ErrorOr<void> DiskCache::PageCache::write_sector(StorageDevice& device, uint64_t sector, const uint8_t* buffer)
|
||||
{
|
||||
ASSERT(device.sector_size() <= PAGE_SIZE);
|
||||
|
||||
uint64_t sectors_per_page = PAGE_SIZE / device.sector_size();
|
||||
uint64_t sector_offset = sector - this->first_sector;
|
||||
|
||||
ASSERT(sector_offset < sectors_per_page);
|
||||
|
||||
PageTable& page_table = PageTable::current();
|
||||
|
||||
page_table.lock();
|
||||
ASSERT(page_table.is_page_free(0));
|
||||
|
||||
page_table.map_page_at(this->paddr, 0, PageTable::Flags::ReadWrite | PageTable::Flags::Present);
|
||||
|
||||
{
|
||||
CriticalScope _;
|
||||
memcpy((void*)(sector_offset * device.sector_size()), buffer, device.sector_size());
|
||||
this->sector_mask |= 1 << sector_offset;
|
||||
this->dirty_mask |= 1 << sector_offset;
|
||||
}
|
||||
|
||||
page_table.unmap_page(0);
|
||||
|
||||
page_table.unlock();
|
||||
|
||||
return {};
|
||||
release_pages(m_cache.size());
|
||||
}
|
||||
|
||||
}
|
|
@ -251,35 +251,41 @@ namespace Kernel
|
|||
|
||||
StorageDevice::~StorageDevice()
|
||||
{
|
||||
if (m_disk_cache)
|
||||
delete m_disk_cache;
|
||||
m_disk_cache = nullptr;
|
||||
}
|
||||
|
||||
void StorageDevice::add_disk_cache()
|
||||
{
|
||||
ASSERT(m_disk_cache == nullptr);
|
||||
m_disk_cache = new DiskCache(*this);
|
||||
ASSERT(m_disk_cache);
|
||||
ASSERT(!m_disk_cache.has_value());
|
||||
m_disk_cache = DiskCache(sector_size());
|
||||
}
|
||||
|
||||
BAN::ErrorOr<void> StorageDevice::read_sectors(uint64_t lba, uint8_t sector_count, uint8_t* buffer)
|
||||
{
|
||||
if (!m_disk_cache)
|
||||
return read_sectors_impl(lba, sector_count, buffer);
|
||||
for (uint8_t sector = 0; sector < sector_count; sector++)
|
||||
TRY(m_disk_cache->read_sector(lba + sector, buffer + sector * sector_size()));
|
||||
for (uint8_t offset = 0; offset < sector_count; offset++)
|
||||
{
|
||||
uint8_t* buffer_ptr = buffer + offset * sector_size();
|
||||
if (m_disk_cache.has_value())
|
||||
if (m_disk_cache->read_from_cache(lba + offset, buffer_ptr))
|
||||
continue;
|
||||
TRY(read_sectors_impl(lba + offset, 1, buffer_ptr));
|
||||
if (m_disk_cache.has_value())
|
||||
(void)m_disk_cache->write_to_cache(lba + offset, buffer_ptr, false);
|
||||
}
|
||||
|
||||
return {};
|
||||
}
|
||||
|
||||
BAN::ErrorOr<void> StorageDevice::write_sectors(uint64_t lba, uint8_t sector_count, const uint8_t* buffer)
|
||||
{
|
||||
if (!m_disk_cache)
|
||||
return write_sectors_impl(lba, sector_count, buffer);
|
||||
// TODO: use disk cache for dirty pages. I don't wanna think about how to do it safely now
|
||||
for (uint8_t sector = 0; sector < sector_count; sector++)
|
||||
TRY(m_disk_cache->write_sector(lba + sector, buffer + sector * sector_size()));
|
||||
{
|
||||
TRY(write_sectors_impl(lba + sector, 1, buffer));
|
||||
if (m_disk_cache.has_value())
|
||||
(void)m_disk_cache->write_to_cache(lba + sector, buffer + sector * sector_size(), false);
|
||||
}
|
||||
|
||||
return {};
|
||||
}
|
||||
|
||||
|
||||
}
|
Loading…
Reference in New Issue