mirror of
https://github.com/SerenityOS/serenity
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fea3cb5ff9
This commit reached that goal of "safely discarding" a filesystem by doing the following: 1. Stop using the s_file_system_map HashMap as it was an unsafe measure to access pointers of FileSystems. Instead, make sure to register all FileSystems at the VFS layer, with an IntrusiveList, to avoid problems related to OOM conditions. 2. Make sure to cleanly remove the DiskCache object from a BlockBased filesystem, so the destructor of such object will not need to do that in the destruction point. 3. For ext2 filesystems, don't cache the root inode at m_inode_cache HashMap. The reason for this is that when unmounting an ext2 filesystem, we lookup at the cache to see if there's a reference to a cached inode and if that's the case, we fail with EBUSY. If we keep the m_root_inode also being referenced at the m_inode_cache map, we have 2 references to that object, which will lead to fail with EBUSY. Also, it's much simpler to always ask for a root inode and get it immediately from m_root_inode, instead of looking up the cache for that inode.
54 lines
1.7 KiB
C++
54 lines
1.7 KiB
C++
/*
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* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <Kernel/FileSystem/FileBackedFileSystem.h>
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#include <Kernel/Locking/MutexProtected.h>
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namespace Kernel {
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class BlockBasedFileSystem : public FileBackedFileSystem {
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public:
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AK_TYPEDEF_DISTINCT_ORDERED_ID(u64, BlockIndex);
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virtual ~BlockBasedFileSystem() override;
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u64 logical_block_size() const { return m_logical_block_size; };
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virtual void flush_writes() override;
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void flush_writes_impl();
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protected:
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explicit BlockBasedFileSystem(OpenFileDescription&);
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virtual ErrorOr<void> initialize_while_locked() override;
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ErrorOr<void> read_block(BlockIndex, UserOrKernelBuffer*, size_t count, u64 offset = 0, bool allow_cache = true) const;
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ErrorOr<void> read_blocks(BlockIndex, unsigned count, UserOrKernelBuffer&, bool allow_cache = true) const;
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ErrorOr<void> raw_read(BlockIndex, UserOrKernelBuffer&);
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ErrorOr<void> raw_write(BlockIndex, UserOrKernelBuffer const&);
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ErrorOr<void> raw_read_blocks(BlockIndex index, size_t count, UserOrKernelBuffer&);
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ErrorOr<void> raw_write_blocks(BlockIndex index, size_t count, UserOrKernelBuffer const&);
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ErrorOr<void> write_block(BlockIndex, UserOrKernelBuffer const&, size_t count, u64 offset = 0, bool allow_cache = true);
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ErrorOr<void> write_blocks(BlockIndex, unsigned count, UserOrKernelBuffer const&, bool allow_cache = true);
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u64 m_logical_block_size { 512 };
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void remove_disk_cache_before_last_unmount();
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private:
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DiskCache& cache() const;
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void flush_specific_block_if_needed(BlockIndex index);
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mutable MutexProtected<OwnPtr<DiskCache>> m_cache;
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};
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}
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