GFS2: Add Orlov allocator

Just like ext3, this works on the root directory and any directory
with the +T flag set. Also, just like ext3, any subdirectory created
in one of the just mentioned cases will be allocated to a random
resource group (GFS2 equivalent of a block group).

If you are creating a set of directories, each of which will contain a
job running on a different node, then by setting +T on the parent
directory before creating the subdirectories, each will land up in a
different resource group, and thus resource group contention between
nodes will be kept to a minimum.

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

fs/gfs2/bmap.c

@@ -1178,7 +1178,7 @@ static int do_grow(struct inode *inode, u64 size)
 		if (error)
 			return error;
 
-		error = gfs2_inplace_reserve(ip, 1);
+		error = gfs2_inplace_reserve(ip, 1, 0);
 		if (error)
 			goto do_grow_qunlock;
 		unstuff = 1;