. test74 for mmap functionality
. vm: add a mem_file memory type that specifies an mmap()ped
memory range, backed by a file
. add fdref, an object that keeps track of FD references within
VM per process and so knows how to de-duplicate the use of FD's
by various mmap()ped ranges; there can be many more than there can
be FD's
. turned off for now, enable with 'filemap=1' as boot option
Change-Id: I640b1126cdaa522a0560301cf6732b7661555672
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
