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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/Devices/KCOVDevice.h
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@ -22,7 +22,7 @@ public:
static void free_process();
// ^File
ErrorOr<Memory::Region*> mmap(Process&, Memory::AddressSpace&, OpenFileDescription&, Memory::VirtualRange const&, u64 offset, int prot, bool shared) override;
ErrorOr<NonnullLockRefPtr<Memory::VMObject>> vmobject_for_mmap(Process&, Memory::VirtualRange const&, u64& offset, bool shared) override;
ErrorOr<NonnullLockRefPtr<OpenFileDescription>> open(int options) override;
protected: