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https://github.com/RGBCube/serenity
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This device is a block device that allows a user to effectively treat an Inode as a block device. The static construction method is given an OpenFileDescription reference but validates that: - The description has a valid custody (so it's not some arbitrary file). Failing this requirement will yield EINVAL. - The description custody points to an Inode which is a regular file, as we only support (seekable) regular files. Failing this requirement will yield ENOTSUP. LoopDevice can be used to mount a regular file on the filesystem like other supported types of (physical) block devices.
62 lines
2 KiB
C++
62 lines
2 KiB
C++
/*
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* Copyright (c) 2024, Liav A. <liavalb@hotmail.co.il>
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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 <AK/Badge.h>
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#include <AK/IntrusiveList.h>
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#include <Kernel/Devices/BlockDevice.h>
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#include <Kernel/FileSystem/Inode.h>
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#include <Kernel/Forward.h>
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#include <Kernel/Library/ListedRefCounted.h>
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namespace Kernel {
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class LoopDevice final : public BlockDevice {
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friend class DeviceManagement;
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public:
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virtual bool unref() const override;
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virtual ~LoopDevice() = default;
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void remove(Badge<DeviceControlDevice>);
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static ErrorOr<NonnullRefPtr<LoopDevice>> create_with_file_description(OpenFileDescription&);
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virtual StringView class_name() const override { return "LoopDevice"sv; }
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virtual ErrorOr<size_t> read(OpenFileDescription&, u64, UserOrKernelBuffer&, size_t) override;
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virtual ErrorOr<size_t> write(OpenFileDescription&, u64, UserOrKernelBuffer const&, size_t) override;
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virtual bool can_read(OpenFileDescription const&, u64) const override;
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virtual bool can_write(OpenFileDescription const&, u64) const override;
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virtual ErrorOr<void> ioctl(OpenFileDescription&, unsigned request, Userspace<void*> arg) override;
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virtual bool is_loop_device() const override { return true; }
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unsigned index() const { return m_index; }
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Inode const& inode() const { return m_backing_custody->inode(); }
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Inode& inode() { return m_backing_custody->inode(); }
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Custody const& custody() const { return *m_backing_custody; }
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Custody& custody() { return *m_backing_custody; }
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private:
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virtual void start_request(AsyncBlockDeviceRequest&) override;
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LoopDevice(NonnullRefPtr<Custody>, unsigned index);
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NonnullRefPtr<Custody> const m_backing_custody;
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unsigned const m_index { 0 };
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mutable IntrusiveListNode<LoopDevice, NonnullRefPtr<LoopDevice>> m_list_node;
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public:
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using List = IntrusiveList<&LoopDevice::m_list_node>;
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static SpinlockProtected<LoopDevice::List, LockRank::None>& all_instances();
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};
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}
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