[GFS2] Clean up inode number handling

This patch cleans up the inode number handling code. The main difference
is that instead of looking up the inodes using a struct gfs2_inum_host
we now use just the no_addr member of this structure. The tests relating
to no_formal_ino can then be done by the calling code. This has
advantages in that we want to do different things in different code
paths if the no_formal_ino doesn't match. In the NFS patch we want to
return -ESTALE, but in the ->lookup() path, its a bug in the fs if the
no_formal_ino doesn't match and thus we can withdraw in this case.

In order to later fix bz #201012, we need to be able to look up an inode
without knowing no_formal_ino, as the only information that is known to
us is the on-disk location of the inode in question.

This patch will also help us to fix bz #236099 at a later date by
cleaning up a lot of the code in that area.

There are no user visible changes as a result of this patch and there
are no changes to the on-disk format either.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/incore.h

@@ -213,8 +213,8 @@ enum {
 
 struct gfs2_inode {
 	struct inode i_inode;
-	struct gfs2_inum_host i_num;
-
+	u64 i_no_addr;
+	u64 i_no_formal_ino;
 	unsigned long i_flags;		/* GIF_... */
 
 	struct gfs2_dinode_host i_di; /* To be replaced by ref to block */