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Ext2FS: Shrink Ext2FSDirectoryEntry from 16 to 12 bytes

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The way we read/write directories is very inefficient, and this doesn't
solve any of that. It does however reduce memory usage of directory
entry vectors by 25% which has nice immediate benefits.
This commit is contained in:
Andreas Kling 2021-02-11 22:45:50 +01:00
parent cef73f2010
commit a280cdf9ba
2 changed files with 9 additions and 8 deletions
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14
Kernel/FileSystem/Ext2FileSystem.cpp
View file

@ -46,7 +46,7 @@ static const ssize_t max_inline_symlink_length = 60;
struct Ext2FSDirectoryEntry { struct Ext2FSDirectoryEntry {
String name; String name;
InodeIdentifier inode; Ext2FS::InodeIndex inode_index { 0 };
u8 file_type { 0 }; u8 file_type { 0 };
}; };
@ -1020,7 +1020,7 @@ KResult Ext2FSInode::write_directory(const Vector<Ext2FSDirectoryEntry>& entries
dbgln("* Inode: {}, name_len: {}, rec_len: {}, file_type: {}, name: {}", entry.inode.index(), u16(entry.name.length()), u16(record_length), u8(entry.file_type), entry.name); dbgln("* Inode: {}, name_len: {}, rec_len: {}, file_type: {}, name: {}", entry.inode.index(), u16(entry.name.length()), u16(record_length), u8(entry.file_type), entry.name);
#endif #endif
stream << u32(entry.inode.index()); stream << u32(entry.inode_index);
stream << u16(record_length); stream << u16(record_length);
stream << u8(entry.name.length()); stream << u8(entry.name.length());
stream << u8(entry.file_type); stream << u8(entry.file_type);
@ -1069,7 +1069,7 @@ KResult Ext2FSInode::add_child(Inode& child, const StringView& name, mode_t mode
name_already_exists = true; name_already_exists = true;
return false; return false;
} }
entries.append({ entry.name, entry.inode, entry.file_type }); entries.append({ entry.name, entry.inode.index(), entry.file_type });
return true; return true;
}); });
@ -1085,7 +1085,7 @@ KResult Ext2FSInode::add_child(Inode& child, const StringView& name, mode_t mode
if (result.is_error()) if (result.is_error())
return result; return result;
entries.empend(name, child.identifier(), to_ext2_file_type(mode)); entries.empend(name, child.index(), to_ext2_file_type(mode));
result = write_directory(entries); result = write_directory(entries);
if (result.is_error()) if (result.is_error())
return result; return result;
@ -1117,7 +1117,7 @@ KResult Ext2FSInode::remove_child(const StringView& name)
Vector<Ext2FSDirectoryEntry> entries; Vector<Ext2FSDirectoryEntry> entries;
KResult result = traverse_as_directory([&](auto& entry) { KResult result = traverse_as_directory([&](auto& entry) {
if (name != entry.name) if (name != entry.name)
entries.append({ entry.name, entry.inode, entry.file_type }); entries.append({ entry.name, entry.inode.index(), entry.file_type });
return true; return true;
}); });
if (result.is_error()) if (result.is_error())
@ -1444,8 +1444,8 @@ KResult Ext2FS::create_directory(Ext2FSInode& parent_inode, const String& name,
#endif #endif
Vector<Ext2FSDirectoryEntry> entries; Vector<Ext2FSDirectoryEntry> entries;
entries.empend(".", inode->identifier(), static_cast<u8>(EXT2_FT_DIR)); entries.empend(".", inode->index(), static_cast<u8>(EXT2_FT_DIR));
entries.empend("..", parent_inode.identifier(), static_cast<u8>(EXT2_FT_DIR)); entries.empend("..", parent_inode.index(), static_cast<u8>(EXT2_FT_DIR));
auto result = static_cast<Ext2FSInode&>(*inode).write_directory(entries); auto result = static_cast<Ext2FSInode&>(*inode).write_directory(entries);
if (result.is_error()) if (result.is_error())

3
Kernel/FileSystem/Ext2FileSystem.h
View file

@ -98,6 +98,8 @@ class Ext2FS final : public BlockBasedFS {
friend class Ext2FSInode; friend class Ext2FSInode;
public: public:
using InodeIndex = u32;
static NonnullRefPtr<Ext2FS> create(FileDescription&); static NonnullRefPtr<Ext2FS> create(FileDescription&);
virtual ~Ext2FS() override; virtual ~Ext2FS() override;
@ -117,7 +119,6 @@ public:
private: private:
typedef unsigned BlockIndex; typedef unsigned BlockIndex;
typedef unsigned GroupIndex; typedef unsigned GroupIndex;
typedef unsigned InodeIndex;
explicit Ext2FS(FileDescription&); explicit Ext2FS(FileDescription&);
const ext2_super_block& super_block() const { return m_super_block; } const ext2_super_block& super_block() const { return m_super_block; }