This commit introduces message fields, library calls and their calls
in libminxfs for using the new secondary cache, without actually
including that functionality yet. This is to make bisecting problems
that might not be due to the new cache code and reading the patches
easier, and forces the fallback in libminixfs to be working in the
absence of the secondary cache functionality.
Change-Id: I76fc5242864db63d134f86d1ce1446b0072ea337
. move cache size heuristic from mfs there
so mfs and ext2 can share it
. add vfs credentials retrieving function, with
backwards compatability from previous struct
format, to be used by both ext2 and mfs
. fix for ext2 - STATICINIT was fed no.
of bytes instead of no. of elements, overallocating
memory by a megabyte or two for the superblock
