RGBCube/serenity
1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-05-31 07:58:11 +00:00
Code Issues Activity Actions

Kernel: Add a write cache to DiskBackedFS.

Browse source 
This way you can spam small write()s on a file without the kernel writing
to disk every single time. Flushes are included in the FS::sync() operation
and will get triggered regularly by syncd. :^)
This commit is contained in:
Andreas Kling 2019-04-25 22:05:53 +02:00
parent e0cdc5db0d
commit 44673c4f3b
5 changed files with 49 additions and 13 deletions
Download patch file Download diff file Expand all files Collapse all files

37
Kernel/FileSystem/DiskBackedFileSystem.cpp
View file

@ -66,8 +66,10 @@ bool DiskBackedFS::write_block(unsigned index, const ByteBuffer& data)
if (auto* cached_block = block_cache().resource().get({ fsid(), index }))
cached_block->m_buffer = data;
}
DiskOffset base_offset = static_cast<DiskOffset>(index) * static_cast<DiskOffset>(block_size());
return device().write(base_offset, block_size(), data.pointer());
LOCKER(m_lock);
m_write_cache.set(index, data.isolated_copy());
return true;
}
bool DiskBackedFS::write_blocks(unsigned index, unsigned count, const ByteBuffer& data)
@ -75,16 +77,9 @@ bool DiskBackedFS::write_blocks(unsigned index, unsigned count, const ByteBuffer
#ifdef DBFS_DEBUG
kprintf("DiskBackedFileSystem::write_blocks %u x%u\n", index, count);
#endif
// FIXME: Maybe reorder this so we send out the write commands before updating cache?
{
LOCKER(block_cache().lock());
for (unsigned i = 0; i < count; ++i) {
if (auto* cached_block = block_cache().resource().get({ fsid(), index + i }))
cached_block->m_buffer = data.slice(i * block_size(), block_size());
}
}
DiskOffset base_offset = static_cast<DiskOffset>(index) * static_cast<DiskOffset>(block_size());
return device().write(base_offset, count * block_size(), data.pointer());
for (unsigned i = 0; i < count; ++i)
write_block(index + i, data.slice(i * block_size(), block_size()));
return true;
}
ByteBuffer DiskBackedFS::read_block(unsigned index) const
@ -92,6 +87,13 @@ ByteBuffer DiskBackedFS::read_block(unsigned index) const
#ifdef DBFS_DEBUG
kprintf("DiskBackedFileSystem::read_block %u\n", index);
#endif
{
LOCKER(m_lock);
if (auto it = m_write_cache.find(index); it != m_write_cache.end())
return it->value;
}
{
LOCKER(block_cache().lock());
if (auto* cached_block = block_cache().resource().get({ fsid(), index }))
@ -105,6 +107,7 @@ ByteBuffer DiskBackedFS::read_block(unsigned index) const
bool success = device().read(base_offset, block_size(), buffer_pointer);
ASSERT(success);
ASSERT(buffer.size() == block_size());
{
LOCKER(block_cache().lock());
block_cache().resource().put({ fsid(), index }, CachedBlock({ fsid(), index }, buffer));
@ -138,3 +141,13 @@ void DiskBackedFS::set_block_size(unsigned block_size)
return;
m_block_size = block_size;
}
void DiskBackedFS::flush_writes()
{
LOCKER(m_lock);
for (auto& it : m_write_cache) {
DiskOffset base_offset = static_cast<DiskOffset>(it.key) * static_cast<DiskOffset>(block_size());
device().write(base_offset, block_size(), it.value.data());
}
m_write_cache.clear();
}