Add the new external read function. Its temporarily in jdata.c
even though the protoype is in ops_file.h - this will change
shortly. The current implementation will change to a page cache
one when that happens.

In order to effect the above changes, the various internal inodes
now have Linux inodes attached to them. We keep the references to
the Linux inodes, rather than the gfs2_inodes in the super block.

In order to get everything to work correctly I've had to reorder
the init sequence on mount (which I should probably have done
earlier when .gfs2_admin was made visible).
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

Removing the gfs2_databuf structure and using gfs2_bufdata instead
is a step towards allowing journaling of data without requiring the
metadata header on each journaled block. The idea is to merge the
code paths for ordered data with that of journaled data, with the
log operations in lops.c tacking account of the different types of
buffers as they are presented to it. Largely the code path for
metadata will be similar too, but obviously through a different set
of log operations.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>

This patch contains all the core files for GFS2.
Signed-off-by: NDavid Teigland <teigland@redhat.com>
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>