Kernel: Writes to disk are not synchronous anymore

Implement "proper" DiskCache syncing
This commit is contained in:
Bananymous 2023-09-11 01:25:16 +03:00
parent 82b049204d
commit b0c22b61ec
4 changed files with 72 additions and 24 deletions

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@ -7,16 +7,18 @@
namespace Kernel
{
class StorageDevice;
class DiskCache
{
public:
DiskCache(size_t sector_size);
DiskCache(size_t sector_size, StorageDevice&);
~DiskCache();
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();
BAN::ErrorOr<void> sync();
size_t release_clean_pages(size_t);
size_t release_pages(size_t);
void release_all_pages();
@ -32,6 +34,7 @@ namespace Kernel
private:
const size_t m_sector_size;
StorageDevice& m_device;
BAN::Vector<PageCache> m_cache;
};

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@ -76,12 +76,15 @@ namespace Kernel
BAN::Vector<Partition*>& partitions() { return m_partitions; }
const BAN::Vector<Partition*>& partitions() const { return m_partitions; }
BAN::ErrorOr<void> sync_disk_cache();
protected:
virtual BAN::ErrorOr<void> read_sectors_impl(uint64_t lba, uint8_t sector_count, uint8_t* buffer) = 0;
virtual BAN::ErrorOr<void> write_sectors_impl(uint64_t lba, uint8_t sector_count, const uint8_t* buffer) = 0;
void add_disk_cache();
private:
SpinLock m_lock;
BAN::Optional<DiskCache> m_disk_cache;
BAN::Vector<Partition*> m_partitions;

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@ -8,8 +8,9 @@
namespace Kernel
{
DiskCache::DiskCache(size_t sector_size)
DiskCache::DiskCache(size_t sector_size, StorageDevice& device)
: m_sector_size(sector_size)
, m_device(device)
{
ASSERT(PAGE_SIZE % m_sector_size == 0);
ASSERT(PAGE_SIZE / m_sector_size <= sizeof(PageCache::sector_mask) * 8);
@ -31,7 +32,6 @@ namespace Kernel
LockGuard page_table_locker(page_table);
ASSERT(page_table.is_page_free(0));
CriticalScope _;
for (auto& cache : m_cache)
{
if (cache.first_sector < page_cache_start)
@ -42,6 +42,7 @@ namespace Kernel
if (!(cache.sector_mask & (1 << page_cache_offset)))
continue;
CriticalScope _;
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);
@ -62,8 +63,6 @@ namespace Kernel
LockGuard page_table_locker(page_table);
ASSERT(page_table.is_page_free(0));
CriticalScope _;
size_t index = 0;
// Search the cache if the have this sector in memory
@ -76,9 +75,12 @@ namespace Kernel
if (cache.first_sector > page_cache_start)
break;
{
CriticalScope _;
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)
@ -104,25 +106,51 @@ namespace Kernel
return ret.error();
}
{
CriticalScope _;
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);
}
return {};
}
void DiskCache::sync()
BAN::ErrorOr<void> DiskCache::sync()
{
BAN::Vector<uint8_t> sector_buffer;
TRY(sector_buffer.resize(m_sector_size));
PageTable& page_table = PageTable::current();
LockGuard page_table_locker(page_table);
ASSERT(page_table.is_page_free(0));
for (auto& cache : m_cache)
{
for (int i = 0; cache.dirty_mask; i++)
{
if (!(cache.dirty_mask & (1 << i)))
continue;
{
CriticalScope _;
for (auto& cache : m_cache)
ASSERT(cache.dirty_mask == 0);
page_table.map_page_at(cache.paddr, 0, PageTable::Flags::Present);
memcpy(sector_buffer.data(), (void*)(i * m_sector_size), m_sector_size);
page_table.unmap_page(0);
}
TRY(m_device.write_sectors_impl(cache.first_sector + i, 1, sector_buffer.data()));
cache.dirty_mask &= ~(1 << i);
}
}
return {};
}
size_t DiskCache::release_clean_pages(size_t page_count)
{
// NOTE: There might not actually be page_count pages after this
// function returns. The synchronization must be done elsewhere.
CriticalScope _;
size_t released = 0;
for (size_t i = 0; i < m_cache.size() && released < page_count;)
@ -147,8 +175,9 @@ namespace Kernel
size_t released = release_clean_pages(page_count);
if (released >= page_count)
return released;
ASSERT_NOT_REACHED();
if (!sync().is_error())
released += release_clean_pages(page_count - released);
return released;
}
void DiskCache::release_all_pages()

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@ -3,6 +3,7 @@
#include <BAN/StringView.h>
#include <BAN/UTF8.h>
#include <kernel/FS/VirtualFileSystem.h>
#include <kernel/LockGuard.h>
#include <kernel/PCI.h>
#include <kernel/Storage/StorageDevice.h>
#include <kernel/Thread.h>
@ -257,15 +258,26 @@ namespace Kernel
void StorageDevice::add_disk_cache()
{
LockGuard _(m_lock);
ASSERT(!m_disk_cache.has_value());
m_disk_cache = DiskCache(sector_size());
m_disk_cache = DiskCache(sector_size(), *this);
}
BAN::ErrorOr<void> StorageDevice::sync_disk_cache()
{
LockGuard _(m_lock);
if (m_disk_cache.has_value())
TRY(m_disk_cache->sync());
return {};
}
BAN::ErrorOr<void> StorageDevice::read_sectors(uint64_t lba, uint8_t sector_count, uint8_t* buffer)
{
for (uint8_t offset = 0; offset < sector_count; offset++)
{
Thread::TerminateBlocker _(Thread::current());
LockGuard _(m_lock);
Thread::TerminateBlocker blocker(Thread::current());
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))
@ -283,11 +295,12 @@ namespace Kernel
// TODO: use disk cache for dirty pages. I don't wanna think about how to do it safely now
for (uint8_t offset = 0; offset < sector_count; offset++)
{
Thread::TerminateBlocker _(Thread::current());
LockGuard _(m_lock);
Thread::TerminateBlocker blocker(Thread::current());
const uint8_t* buffer_ptr = buffer + offset * sector_size();
if (!m_disk_cache.has_value() || m_disk_cache->write_to_cache(lba + offset, buffer_ptr, true).is_error())
TRY(write_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 {};