UBI: prepare for protection tree improvements

This patch modifies @struct ubi_wl_entry and adds union which
contains only one element so far. This is just a preparation
for further changes which will kill the protection tree and
make UBI use a list instead.

Signed-off-by: Xiaochuan-Xu <xiaochuan-xu@cqu.edu.cn>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

2 files changed, 27 insertions, 24 deletions

diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 1c3fa18c26a..46a4763f8e7 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -95,7 +95,7 @@ enum {
 
 /**
  * struct ubi_wl_entry - wear-leveling entry.
- * @rb: link in the corresponding RB-tree
+ * @u.rb: link in the corresponding (free/used) RB-tree
  * @ec: erase counter
  * @pnum: physical eraseblock number
  *
@@ -104,7 +104,9 @@ enum {
  * RB-trees. See WL sub-system for details.
  */
 struct ubi_wl_entry {
-        struct rb_node rb;
+        union {
+                struct rb_node rb;
+        } u;
         int ec;
         int pnum;
 };
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index abf65ea414e..0279bf9dc72 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -220,7 +220,7 @@ static void wl_tree_add(struct ubi_wl_entry *e, struct rb_root *root)
                 struct ubi_wl_entry *e1;
 
                 parent = *p;
-                e1 = rb_entry(parent, struct ubi_wl_entry, rb);
+                e1 = rb_entry(parent, struct ubi_wl_entry, u.rb);
 
                 if (e->ec < e1->ec)
                         p = &(*p)->rb_left;
@@ -235,8 +235,8 @@ static void wl_tree_add(struct ubi_wl_entry *e, struct rb_root *root)
                 }
         }
 
-        rb_link_node(&e->rb, parent, p);
-        rb_insert_color(&e->rb, root);
+        rb_link_node(&e->u.rb, parent, p);
+        rb_insert_color(&e->u.rb, root);
 }
 
 /**
@@ -331,7 +331,7 @@ static int in_wl_tree(struct ubi_wl_entry *e, struct rb_root *root)
         while (p) {
                 struct ubi_wl_entry *e1;
 
-                e1 = rb_entry(p, struct ubi_wl_entry, rb);
+                e1 = rb_entry(p, struct ubi_wl_entry, u.rb);
 
                 if (e->pnum == e1->pnum) {
                         ubi_assert(e == e1);
@@ -413,14 +413,14 @@ static struct ubi_wl_entry *find_wl_entry(struct rb_root *root, int max)
         struct rb_node *p;
         struct ubi_wl_entry *e;
 
-        e = rb_entry(rb_first(root), struct ubi_wl_entry, rb);
+        e = rb_entry(rb_first(root), struct ubi_wl_entry, u.rb);
         max += e->ec;
 
         p = root->rb_node;
         while (p) {
                 struct ubi_wl_entry *e1;
 
-                e1 = rb_entry(p, struct ubi_wl_entry, rb);
+                e1 = rb_entry(p, struct ubi_wl_entry, u.rb);
                 if (e1->ec >= max)
                         p = p->rb_left;
                 else {
@@ -491,12 +491,13 @@ retry:
                  * eraseblock with erase counter greater or equivalent than the
                  * lowest erase counter plus %WL_FREE_MAX_DIFF.
                  */
-                first = rb_entry(rb_first(&ubi->free), struct ubi_wl_entry, rb);
-                last = rb_entry(rb_last(&ubi->free), struct ubi_wl_entry, rb);
+                first = rb_entry(rb_first(&ubi->free), struct ubi_wl_entry,
+                                        u.rb);
+                last = rb_entry(rb_last(&ubi->free), struct ubi_wl_entry, u.rb);
 
                 if (last->ec - first->ec < WL_FREE_MAX_DIFF)
                         e = rb_entry(ubi->free.rb_node,
-                                        struct ubi_wl_entry, rb);
+                                        struct ubi_wl_entry, u.rb);
                 else {
                         medium_ec = (first->ec + WL_FREE_MAX_DIFF)/2;
                         e = find_wl_entry(&ubi->free, medium_ec);
@@ -508,7 +509,7 @@ retry:
                  * For short term data we pick a physical eraseblock with the
                  * lowest erase counter as we expect it will be erased soon.
                  */
-                e = rb_entry(rb_first(&ubi->free), struct ubi_wl_entry, rb);
+                e = rb_entry(rb_first(&ubi->free), struct ubi_wl_entry, u.rb);
                 protect = ST_PROTECTION;
                 break;
         default:
@@ -522,7 +523,7 @@ retry:
          * be protected from being moved for some time.
          */
         paranoid_check_in_wl_tree(e, &ubi->free);
-        rb_erase(&e->rb, &ubi->free);
+        rb_erase(&e->u.rb, &ubi->free);
         prot_tree_add(ubi, e, pe, protect);
 
         dbg_wl("PEB %d EC %d, protection %d", e->pnum, e->ec, protect);
@@ -779,7 +780,7 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
                  * highly worn-out free physical eraseblock. If the erase
                  * counters differ much enough, start wear-leveling.
                  */
-                e1 = rb_entry(rb_first(&ubi->used), struct ubi_wl_entry, rb);
+                e1 = rb_entry(rb_first(&ubi->used), struct ubi_wl_entry, u.rb);
                 e2 = find_wl_entry(&ubi->free, WL_FREE_MAX_DIFF);
 
                 if (!(e2->ec - e1->ec >= UBI_WL_THRESHOLD)) {
@@ -788,21 +789,21 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
                         goto out_cancel;
                 }
                 paranoid_check_in_wl_tree(e1, &ubi->used);
-                rb_erase(&e1->rb, &ubi->used);
+                rb_erase(&e1->u.rb, &ubi->used);
                 dbg_wl("move PEB %d EC %d to PEB %d EC %d",
                        e1->pnum, e1->ec, e2->pnum, e2->ec);
         } else {
                 /* Perform scrubbing */
                 scrubbing = 1;
-                e1 = rb_entry(rb_first(&ubi->scrub), struct ubi_wl_entry, rb);
+                e1 = rb_entry(rb_first(&ubi->scrub), struct ubi_wl_entry, u.rb);
                 e2 = find_wl_entry(&ubi->free, WL_FREE_MAX_DIFF);
                 paranoid_check_in_wl_tree(e1, &ubi->scrub);
-                rb_erase(&e1->rb, &ubi->scrub);
+                rb_erase(&e1->u.rb, &ubi->scrub);
                 dbg_wl("scrub PEB %d to PEB %d", e1->pnum, e2->pnum);
         }
 
         paranoid_check_in_wl_tree(e2, &ubi->free);
-        rb_erase(&e2->rb, &ubi->free);
+        rb_erase(&e2->u.rb, &ubi->free);
         ubi->move_from = e1;
         ubi->move_to = e2;
         spin_unlock(&ubi->wl_lock);
@@ -1012,7 +1013,7 @@ static int ensure_wear_leveling(struct ubi_device *ubi)
                  * erase counter of free physical eraseblocks is greater then
                  * %UBI_WL_THRESHOLD.
                  */
-                e1 = rb_entry(rb_first(&ubi->used), struct ubi_wl_entry, rb);
+                e1 = rb_entry(rb_first(&ubi->used), struct ubi_wl_entry, u.rb);
                 e2 = find_wl_entry(&ubi->free, WL_FREE_MAX_DIFF);
 
                 if (!(e2->ec - e1->ec >= UBI_WL_THRESHOLD))
@@ -1214,10 +1215,10 @@ retry:
         } else {
                 if (in_wl_tree(e, &ubi->used)) {
                         paranoid_check_in_wl_tree(e, &ubi->used);
-                        rb_erase(&e->rb, &ubi->used);
+                        rb_erase(&e->u.rb, &ubi->used);
                 } else if (in_wl_tree(e, &ubi->scrub)) {
                         paranoid_check_in_wl_tree(e, &ubi->scrub);
-                        rb_erase(&e->rb, &ubi->scrub);
+                        rb_erase(&e->u.rb, &ubi->scrub);
                 } else {
                         err = prot_tree_del(ubi, e->pnum);
                         if (err) {
@@ -1279,7 +1280,7 @@ retry:
 
         if (in_wl_tree(e, &ubi->used)) {
                 paranoid_check_in_wl_tree(e, &ubi->used);
-                rb_erase(&e->rb, &ubi->used);
+                rb_erase(&e->u.rb, &ubi->used);
         } else {
                 int err;
 
@@ -1361,11 +1362,11 @@ static void tree_destroy(struct rb_root *root)
                 else if (rb->rb_right)
                         rb = rb->rb_right;
                 else {
-                        e = rb_entry(rb, struct ubi_wl_entry, rb);
+                        e = rb_entry(rb, struct ubi_wl_entry, u.rb);
 
                         rb = rb_parent(rb);
                         if (rb) {
-                                if (rb->rb_left == &e->rb)
+                                if (rb->rb_left == &e->u.rb)
                                         rb->rb_left = NULL;
                                 else
                                         rb->rb_right = NULL;