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Ext2FS: Use KBuffers for the cached bitmap blocks

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Also cache the block group descriptor table in a KBuffer on file system
initialization, instead of on first access.

This reduces pressure on the kmalloc heap somewhat.
This commit is contained in:
Andreas Kling 2019-11-03 00:10:24 +01:00
parent ddd8332015
commit 1e36d899f1
2 changed files with 15 additions and 22 deletions
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13
Kernel/FileSystem/Ext2FileSystem.h
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@ -1,6 +1,7 @@
#pragma once
#include <AK/Bitmap.h>
#include <Kernel/KBuffer.h>
#include <Kernel/FileSystem/DiskBackedFileSystem.h>
#include <Kernel/FileSystem/Inode.h>
#include <Kernel/FileSystem/ext2_fs.h>
@ -80,7 +81,9 @@ private:
explicit Ext2FS(NonnullRefPtr<DiskDevice>&&);
const ext2_super_block& super_block() const { return m_super_block; }
const ext2_group_desc& group_descriptor(unsigned groupIndex) const;
const ext2_group_desc& group_descriptor(GroupIndex) const;
ext2_group_desc* block_group_descriptors() { return (ext2_group_desc*)m_cached_group_descriptor_table.value().data(); }
const ext2_group_desc* block_group_descriptors() const { return (const ext2_group_desc*)m_cached_group_descriptor_table.value().data(); }
void flush_block_group_descriptor_table();
unsigned first_block_of_group(unsigned groupIndex) const;
unsigned inodes_per_block() const;
@ -130,7 +133,7 @@ private:
unsigned m_block_group_count { 0 };
mutable ext2_super_block m_super_block;
mutable ByteBuffer m_cached_group_descriptor_table;
mutable Optional<KBuffer> m_cached_group_descriptor_table;
mutable HashMap<BlockIndex, RefPtr<Ext2FSInode>> m_inode_cache;
@ -138,13 +141,13 @@ private:
bool m_block_group_descriptors_dirty { false };
struct CachedBitmap {
CachedBitmap(BlockIndex bi, ByteBuffer&& buf)
CachedBitmap(BlockIndex bi, KBuffer&& buf)
: bitmap_block_index(bi)
, buffer(buf)
, buffer(move(buf))
{}
BlockIndex bitmap_block_index { 0 };
bool dirty { false };
ByteBuffer buffer;
KBuffer buffer;
Bitmap bitmap(u32 blocks_per_group) { return Bitmap::wrap(buffer.data(), blocks_per_group); }
};