Uncovered a mmap() bug that came along this far. file_offset
parameter of do_mmap() was assigned to the mapped vma as is, i.e.
as a byte offset. This caused problems since most page fault and
other internal code assumed this was a page frame number. This is now
fixed. This came along unnoticed since all mmaps until now started at
file offset 0.
Increased inode block pointers to 40. The current maximum allowed (and checked).
Updates to file size after every file write ensures subsequent writes can
correctly operate using updated file size information (i.e. not try to add
more pages that are already present). We cannot do this inside write() because
directory writes rely on byte-granularity updates on file buffers, whereas
file updates are by page-granularity (currently).
It turned out we used one version of kmalloc for malloc() and another for kfree()!
Now fixed.
Added parent-child relationship to tasks. Need to polish handling CLONE_PARENT and THREAD.
l4_unmap now returns -1 if given range was only partially unmapped.
do_munmap() now only unmaps address ranges that have correspondence in
the unmapped vmas. Trying to unmap regions with no correspondent vmas
causes problems in corner cases, e.g. mm0 that tries to mmap its own
address space during initialisation would unmap its whole address space
and fail to execute.
When sys_munmap() splits a vma, the new vma had no copy of the objects
in the original vma. Now we fixed that using a vma_copy_links() function
which can also be used as part of fork().
Still testing sys_munmap(). It now correctly spots and unmaps the overlapping vma.
The issue now is that if a split occurs, we forgot to add same objects to new vma.
File open was failing when using 2 files with same name. TODO: Look at it in the future.
Need to increase writeable file size in fs0. 16 pages don't work.
do_munmap currently shrinks, splits, destroys vmas and unmaps the given
virtual address range from the task. Unmapped pages may go completely unused
but page reclamation will be done in another part of the pager rather than
directly on the munmap instance.
- Fixed an important bug with shadow object handling.
When a shadow is dropped, if there are references left
to it, both the object in front and dropped object becomes
a shadow of the original object underneath. We had thought
of this case but had not increase the shadow count.
- Added a test mechanism that tests the number of objects,
vmfiles, shadows etc. by first counting them and trying to
reach the same number by other means, i.e. per-object-shadow counts.
It discovered a plethora of bugs.
- Added new set of functions to register objects, files and tasks
globally with the pager, these functions introduce a refcount as
well as adding structures to linked lists.
- fork/exit now seems to work stably i.e. no negative shadow counts etc.
