read_block() and write_block() now accept the count (how many bytes to read
or write) and offset (where in the block to start; defaults to 0). Using these
new APIs, we can avoid doing copies between intermediary buffers in a lot more
cases. Hopefully this improves performance or something.
This was supposed to be the foundation for some kind of pre-kernel
environment, but nobody is working on it right now, so let's move
everything back into the kernel and remove all the confusion.
Since a Region is basically a view into a potentially larger VMObject,
it was always necessary to include the Region starting offset when
accessing its underlying physical pages.
Until now, you had to do that manually, but this patch adds a simple
Region::physical_page() for read-only access and a physical_page_slot()
when you want a mutable reference to the RefPtr<PhysicalPage> itself.
A lot of code is simplified by making use of this.
The next commit is going to make it bigger again by increasing the size of Lock,
so make use of bitfields to make sure FileDescription still fits into 64 bytes,
and so can still be allocated with the SlabAllocator.
In contrast to the previous patchset that was reverted, this time we use
a "special" method to access a file with block size of 512 bytes (like
a harddrive essentially).
We were allowing this dangerous kind of thing:
RefPtr<Base> base;
RefPtr<Derived> derived = base;
This patch changes the {Nonnull,}RefPtr constructors so this is no
longer possible.
To downcast one of these pointers, there is now static_ptr_cast<T>:
RefPtr<Derived> derived = static_ptr_cast<Derived>(base);
Fixing this exposed a ton of cowboy-downcasts in various places,
which we're now forced to fix. :^)
This was causing some obvious-in-hindsight but hard to spot bugs where
we'd implicitly convert the bool to an integer type and carry on with
the number 1 instead of the actual value().
Also, duplicate data in dbg() and klog() calls were removed.
In addition, leakage of virtual address to kernel log is prevented.
This is done by replacing kprintf() calls to dbg() calls with the
leaked data instead.
Also, other kprintf() calls were replaced with klog().
We don't have to log the process name/PID/TID, dbg() automatically adds
that as a prefix to every line.
Also we don't have to do .characters() on Strings passed to dbg() :^)
You can now mmap a file as private and writable, and the changes you
make will only be visible to you.
This works because internally a MAP_PRIVATE region is backed by a
unique PrivateInodeVMObject instead of using the globally shared
SharedInodeVMObject like we always did before. :^)
Fixes#1045.
