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https://github.com/SerenityOS/serenity
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30861daa93
Before this change, we had File::mmap() which did all the work of setting up a VMObject, and then creating a Region in the current process's address space. This patch simplifies the interface by removing the region part. Files now only have to return a suitable VMObject from vmobject_for_mmap(), and then sys$mmap() itself will take care of actually mapping it into the address space. This fixes an issue where we'd try to block on I/O (for inode metadata lookup) while holding the address space spinlock. It also reduces time spent holding the address space lock.
38 lines
1.2 KiB
C++
38 lines
1.2 KiB
C++
/*
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* Copyright (c) 2021, 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/Types.h>
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#include <Kernel/Devices/CharacterDevice.h>
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#include <Kernel/PhysicalAddress.h>
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namespace Kernel {
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class MemoryDevice final : public CharacterDevice {
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friend class DeviceManagement;
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public:
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static NonnullLockRefPtr<MemoryDevice> must_create();
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~MemoryDevice();
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virtual ErrorOr<NonnullLockRefPtr<Memory::VMObject>> vmobject_for_mmap(Process&, Memory::VirtualRange const&, u64& offset, bool shared) override;
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private:
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MemoryDevice();
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virtual StringView class_name() const override { return "MemoryDevice"sv; }
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virtual bool can_read(OpenFileDescription const&, u64) const override { return true; }
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virtual bool can_write(OpenFileDescription const&, u64) const override { return false; }
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virtual bool is_seekable() const override { return true; }
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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 { return EINVAL; }
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bool is_allowed_range(PhysicalAddress, Memory::VirtualRange const&) const;
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};
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}
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