Files
serenity/Kernel/FileSystem/DevLoopFS/Inode.h
implicitfield 6a4ceb6bf2 Kernel: Avoid double-locking devices when trying to acquire them
Previously, you'd occasionally see this sort of construct (simplified):
```
return FooDevice::all_instances().with([&](auto& list) {
    for (auto& device : list) {
        if (/* search condition */)
            continue;
        return do_something_that_reacquires(device.index());
    }
    return ENOENT;
});
```

This would only work if the relevant `all_instances()` used a recursive
spinlock, since reacquiring the device would lock that again.

To get around this, a new helper has been added in `Device` through
which devices can be accessed whilst locking the device list, removing
the need to loop through the device type's `all_instances()`.
2025-06-05 22:02:40 +02:00

49 lines
1.7 KiB
C++

/*
* Copyright (c) 2024, Liav A. <liavalb@hotmail.co.il>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Types.h>
#include <Kernel/Devices/Loop/LoopDevice.h>
#include <Kernel/FileSystem/DevLoopFS/FileSystem.h>
#include <Kernel/FileSystem/Inode.h>
namespace Kernel {
class DevLoopFSInode final : public Inode {
friend class DevLoopFS;
public:
virtual ~DevLoopFSInode() override;
DevLoopFS& fs() { return static_cast<DevLoopFS&>(Inode::fs()); }
DevLoopFS const& fs() const { return static_cast<DevLoopFS const&>(Inode::fs()); }
private:
DevLoopFSInode(DevLoopFS&, InodeIndex, LockWeakPtr<LoopDevice>);
// NOTE: This constructor is used for the root inode only.
DevLoopFSInode(DevLoopFS&);
// ^Inode
virtual ErrorOr<size_t> read_bytes_locked(off_t, size_t, UserOrKernelBuffer& buffer, OpenFileDescription*) const override;
virtual InodeMetadata metadata() const override;
virtual ErrorOr<void> traverse_as_directory(Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)>) const override;
virtual ErrorOr<NonnullRefPtr<Inode>> lookup(StringView name) override;
virtual ErrorOr<void> flush_metadata() override;
virtual ErrorOr<size_t> write_bytes_locked(off_t, size_t, UserOrKernelBuffer const& buffer, OpenFileDescription*) override;
virtual ErrorOr<NonnullRefPtr<Inode>> create_child(StringView name, mode_t, dev_t, UserID, GroupID) override;
virtual ErrorOr<void> add_child(Inode&, StringView name, mode_t) override;
virtual ErrorOr<void> remove_child(StringView name) override;
virtual ErrorOr<void> chmod(mode_t) override;
virtual ErrorOr<void> chown(UserID, GroupID) override;
LockWeakPtr<LoopDevice> m_loop_device;
InodeMetadata m_metadata;
};
}