vm_page::Init().
* Made vm_page::wired_count private and added accessor methods.
* Added VMCache::fWiredPagesCount (the number of wired pages the cache
contains) and accessor methods.
* Made more use of vm_page::IsMapped().
* vm_copy_on_write_area(): Added vm_page_reservation* parameter that can be
used to request a special handling for wired pages. If given the wired pages
are replaced by copies and the original pages are moved to the upper cache.
* vm_copy_area():
- We don't need to do any wired ranges handling, if the source area is a
B_SHARED_AREA, since we don't touch the area's mappings in this case.
- We no longer wait for wired ranges of the concerned areas to disappear.
Instead we use the new vm_copy_on_write_area() feature and just let it
copy the wired pages. This fixes#6288, an issue introduced with the use
of user mutexes in libroot: When executing multiple concurrent fork()s all
but the first one would wait on the fork mutex, which (being a user mutex)
would wire a page that the vm_copy_area() of the first fork() would wait
for.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@37460 a95241bf-73f2-0310-859d-f6bbb57e9c96
b944766870