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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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4
Kernel/FileSystem/OpenFileDescription.cpp
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@ -374,9 +374,9 @@ InodeMetadata OpenFileDescription::metadata() const
return {};
}
ErrorOr<Memory::Region*> OpenFileDescription::mmap(Process& process, Memory::AddressSpace& address_space, Memory::VirtualRange const& range, u64 offset, int prot, bool shared)
ErrorOr<NonnullLockRefPtr<Memory::VMObject>> OpenFileDescription::vmobject_for_mmap(Process& process, Memory::VirtualRange const& range, u64& offset, bool shared)
{
return m_file->mmap(process, address_space, *this, range, offset, prot, shared);
return m_file->vmobject_for_mmap(process, range, offset, shared);
}
ErrorOr<void> OpenFileDescription::truncate(u64 length)