ore: Remove redundant dev_order(), more cleanups

Two cleanups:
* si->cur_comp, si->cur_pg where always calculated after
  the call to ore_calc_stripe_info() with the help of
  _dev_order(...). But these are already calculated by
  ore_calc_stripe_info() and can be just set there.
  (This is left over from the time that si->cur_comp, si->cur_pg
   were only used by raid code, but now the main loop manages
   them anyway even though they are ultimately not used in
   none raid code)

* si->cur_comp - For the very last stripe case, was set inside
  _ore_add_parity_unit(). This is not clear and will be wrong
  for coming raid6 so move this to only caller. Now si->cur_comp
  is only manipulated within _prepare_for_striping(), always next
  to the manipulation of cur_dev.
  Which is much easier to understand and follow.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
diff --git a/fs/exofs/ore_raid.c b/fs/exofs/ore_raid.c
index af417d3..d58a952 100644
--- a/fs/exofs/ore_raid.c
+++ b/fs/exofs/ore_raid.c
@@ -402,9 +402,8 @@
 
 	ore_calc_stripe_info(ios->layout, *offset, 0, &si);
 
-	p = si.unit_off / PAGE_SIZE;
-	c = _dev_order(ios->layout->group_width * ios->layout->mirrors_p1,
-		       ios->layout->mirrors_p1, si.par_dev, si.dev);
+	p = si.cur_pg;
+	c = si.cur_comp;
 	page = ios->sp2d->_1p_stripes[p].pages[c];
 
 	pg_len = PAGE_SIZE - (si.unit_off % PAGE_SIZE);
@@ -532,9 +531,8 @@
 		goto read_it;
 
 	ore_calc_stripe_info(ios->layout, offset, 0, &read_si);
-	p = read_si.unit_off / PAGE_SIZE;
-	c = _dev_order(ios->layout->group_width * ios->layout->mirrors_p1,
-		       ios->layout->mirrors_p1, read_si.par_dev, read_si.dev);
+	p = read_si.cur_pg;
+	c = read_si.cur_comp;
 
 	if (min_p == sp2d->pages_in_unit) {
 		/* Didn't do it yet */
@@ -638,9 +636,6 @@
 		si->cur_pg = _sp2d_min_pg(sp2d);
 		num_pages  = _sp2d_max_pg(sp2d) + 1 - si->cur_pg;
 
-		if (!cur_len) /* If last stripe operate on parity comp */
-			si->cur_comp = sp2d->data_devs;
-
 		if (!per_dev->length) {
 			per_dev->offset += si->cur_pg * PAGE_SIZE;
 			/* If first stripe, Read in all read4write pages