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Kernel: Simplify the File memory-mapping API

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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.
This commit is contained in:
Andreas Kling 2022-08-23 18:51:18 +02:00
parent cf16b2c8e6
commit 30861daa93
15 changed files with 49 additions and 58 deletions
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2
Kernel/Graphics/DisplayConnector.h
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@ -137,7 +137,7 @@ private:
virtual bool can_write(OpenFileDescription const&, u64) const final override { return true; }
virtual ErrorOr<size_t> read(OpenFileDescription&, u64, UserOrKernelBuffer&, size_t) override final;
virtual ErrorOr<size_t> write(OpenFileDescription&, u64, UserOrKernelBuffer const&, size_t) override final;
virtual ErrorOr<Memory::Region*> mmap(Process&, Memory::AddressSpace&, OpenFileDescription&, Memory::VirtualRange const&, u64, int, bool) override final;
virtual ErrorOr<NonnullLockRefPtr<Memory::VMObject>> vmobject_for_mmap(Process&, Memory::VirtualRange const&, u64&, bool) override final;
virtual ErrorOr<void> ioctl(OpenFileDescription&, unsigned request, Userspace<void*> arg) override final;
virtual StringView class_name() const override final { return "DisplayConnector"sv; }