forked from Bananymous/banan-os
122 lines
3.7 KiB
C++
122 lines
3.7 KiB
C++
#pragma once
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#include <BAN/HashMap.h>
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#include <BAN/Iteration.h>
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#include <kernel/FS/FileSystem.h>
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#include <kernel/FS/TmpFS/Inode.h>
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#include <kernel/SpinLock.h>
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namespace Kernel
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{
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template<typename F>
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concept for_each_indirect_paddr_allocating_callback = requires(F func, paddr_t paddr, bool was_allocated)
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{
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requires BAN::is_same_v<decltype(func(paddr, was_allocated)), BAN::Iteration>;
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};
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class TmpFileSystem : public FileSystem
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{
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public:
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static constexpr size_t no_page_limit = SIZE_MAX;
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public:
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static BAN::ErrorOr<TmpFileSystem*> create(size_t max_pages, mode_t, uid_t, gid_t);
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~TmpFileSystem();
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virtual BAN::RefPtr<Inode> root_inode() override { return m_root_inode; }
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BAN::ErrorOr<BAN::RefPtr<TmpInode>> open_inode(ino_t ino);
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// FIXME: read_block and write_block should not require external buffer
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// probably some wrapper like PageTable::with_fast_page could work?
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void read_inode(ino_t ino, TmpInodeInfo& out);
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void write_inode(ino_t ino, const TmpInodeInfo&);
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void delete_inode(ino_t ino);
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BAN::ErrorOr<ino_t> allocate_inode(const TmpInodeInfo&);
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void read_block(size_t index, BAN::ByteSpan buffer);
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void write_block(size_t index, BAN::ConstByteSpan buffer);
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void free_block(size_t index);
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BAN::ErrorOr<size_t> allocate_block();
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private:
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struct PageInfo
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{
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enum Flags : paddr_t
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{
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Present = 1 << 0,
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};
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// 12 bottom bits of paddr can be used as flags, since
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// paddr will always be page aligned.
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static constexpr size_t flag_bits = 12;
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static constexpr paddr_t flags_mask = (1 << flag_bits) - 1;
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static constexpr paddr_t paddr_mask = ~flags_mask;
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static_assert((1 << flag_bits) <= PAGE_SIZE);
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paddr_t paddr() const { return raw & paddr_mask; }
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paddr_t flags() const { return raw & flags_mask; }
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void set_paddr(paddr_t paddr) { raw = (raw & flags_mask) | (paddr & paddr_mask); }
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void set_flags(paddr_t flags) { raw = (raw & paddr_mask) | (flags & flags_mask); }
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paddr_t raw { 0 };
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};
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struct InodeLocation
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{
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paddr_t paddr;
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size_t index;
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};
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private:
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TmpFileSystem(size_t max_pages);
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BAN::ErrorOr<void> initialize(mode_t, uid_t, gid_t);
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InodeLocation find_inode(ino_t ino);
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paddr_t find_block(size_t index);
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template<for_each_indirect_paddr_allocating_callback F>
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BAN::ErrorOr<void> for_each_indirect_paddr_allocating(PageInfo page_info, F callback, size_t depth);
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template<for_each_indirect_paddr_allocating_callback F>
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BAN::ErrorOr<BAN::Iteration> for_each_indirect_paddr_allocating_internal(PageInfo page_info, F callback, size_t depth);
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paddr_t find_indirect(PageInfo root, size_t index, size_t depth);
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private:
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RecursiveSpinLock m_lock;
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BAN::HashMap<ino_t, BAN::RefPtr<TmpInode>> m_inode_cache;
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BAN::RefPtr<TmpDirectoryInode> m_root_inode;
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// We store pages with triple indirection.
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// With 64-bit pointers we can store 512^3 pages of data (512 GiB)
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// which should be enough for now.
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// In future this should be dynamically calculated based on maximum
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// number of pages for this file system.
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PageInfo m_data_pages {};
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static constexpr size_t first_data_page = 1;
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static constexpr size_t max_data_pages =
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(PAGE_SIZE / sizeof(PageInfo)) *
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(PAGE_SIZE / sizeof(PageInfo)) *
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(PAGE_SIZE / sizeof(PageInfo));
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// We store inodes in pages with double indirection.
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// With 64-bit pointers we can store 512^2 pages of inodes
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// which should be enough for now.
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// In future this should be dynamically calculated based on maximum
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// number of pages for this file system.
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PageInfo m_inode_pages;
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static constexpr size_t first_inode = 1;
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static constexpr size_t max_inodes =
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(PAGE_SIZE / sizeof(PageInfo)) *
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(PAGE_SIZE / sizeof(PageInfo)) *
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(PAGE_SIZE / sizeof(TmpInodeInfo));
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const size_t m_max_pages;
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};
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} |