Primary purpose of change: to support the mmap implementation, VM must
know both (a) about some block metadata for FS cache blocks, i.e.
inode numbers and inode offsets where applicable; and (b) know about
*all* cache blocks, i.e. also of the FS primary caches and not just
the blocks that spill into the secondary one. This changes the
interface and VM data structures.
This change is only for the interface (libminixfs) and VM data
structures; the filesystem code is unmodified, so although the
secondary cache will be used as normal, blocks will not be annotated
with inode information until the FS is modified to provide this
information. Until it is modified, mmap of files will fail gracefully
on such filesystems.
This is indicated to VFS/VM by returning ENOSYS for REQ_PEEK.
Change-Id: I1d2df6c485e6c5e89eb28d9055076cc02629594e
. make vm be able to use malloc() by overriding brk()
and minix_mmap() functions
. phys regions can then be malloc()ed and free()d instead
of being in an avl tree, which is slightly faster
. 'offset' field in phys_region can go too (offset is implied
by position in array) but leads to bigger code changes
Introduce explicit abstractions for different mapping types,
handling the instantiation, forking, pagefaults and freeing of
anonymous memory, direct physical mappings, shared memory and
physically contiguous anonymous memory as separate types, making
region.c more generic.
Also some other genericification like merging the 3 munmap cases
into one.
COW and SMAP safemap code is still implicit in region.c.
