[PATCH v2] lib/btree.c: optimise the code by previously getpos function

[Leno Hou]

This patch optimized the code by previously getpos function call.
Therefore, It's takes the convenience to understand logic of code.

v2:
  - getpos() returns errorno if not found the key

v1:
  - cleanup code by using getpos()

Signed-off-by: Leno Hou <leno...@gmail.com>
---
 lib/btree.c | 50 +++++++++++++++++++++-----------------------------
 1 file changed, 21 insertions(+), 29 deletions(-)

diff --git a/lib/btree.c b/lib/btree.c
index f93a945..8604773 100644
--- a/lib/btree.c
+++ b/lib/btree.c
@@ -238,6 +238,18 @@ static int keyzero(struct btree_geo *geo, unsigned long 
*key)
        return 1;
 }
 
+static int getpos(struct btree_geo *geo, unsigned long *node,
+               unsigned long *key)
+{
+       unsigned int i;
+
+       for (i = 0; i < geo->no_pairs; i++) {
+               if (keycmp(geo, node, i, key) <= 0)
+                       return i;
+       }
+       return -ENOENT;
+}
+
 void *btree_lookup(struct btree_head *head, struct btree_geo *geo,
                unsigned long *key)
 {
@@ -248,10 +260,8 @@ void *btree_lookup(struct btree_head *head, struct 
btree_geo *geo,
                return NULL;
 
        for ( ; height > 1; height--) {
-               for (i = 0; i < geo->no_pairs; i++)
-                       if (keycmp(geo, node, i, key) <= 0)
-                               break;
-               if (i == geo->no_pairs)
+               i = getpos(geo, node, key);
+               if (i < 0)
                        return NULL;
                node = bval(geo, node, i);
                if (!node)
@@ -278,10 +288,8 @@ int btree_update(struct btree_head *head, struct btree_geo 
*geo,
                return -ENOENT;
 
        for ( ; height > 1; height--) {
-               for (i = 0; i < geo->no_pairs; i++)
-                       if (keycmp(geo, node, i, key) <= 0)
-                               break;
-               if (i == geo->no_pairs)
+               i = getpos(geo, node, key);
+               if (i < 0)
                        return -ENOENT;
                node = bval(geo, node, i);
                if (!node)
@@ -326,10 +334,8 @@ void *btree_get_prev(struct btree_head *head, struct 
btree_geo *geo,
 
        node = head->node;
        for (height = head->height ; height > 1; height--) {
-               for (i = 0; i < geo->no_pairs; i++)
-                       if (keycmp(geo, node, i, key) <= 0)
-                               break;
-               if (i == geo->no_pairs)
+               i = getpos(geo, node, key);
+               if (i < 0)
                        goto miss;
                oldnode = node;
                node = bval(geo, node, i);
@@ -360,18 +366,6 @@ void *btree_get_prev(struct btree_head *head, struct 
btree_geo *geo,
 }
 EXPORT_SYMBOL_GPL(btree_get_prev);
 
-static int getpos(struct btree_geo *geo, unsigned long *node,
-               unsigned long *key)
-{
-       int i;
-
-       for (i = 0; i < geo->no_pairs; i++) {
-               if (keycmp(geo, node, i, key) <= 0)
-                       break;
-       }
-       return i;
-}
-
 static int getfill(struct btree_geo *geo, unsigned long *node, int start)
 {
        int i;
@@ -392,11 +386,9 @@ static unsigned long *find_level(struct btree_head *head, 
struct btree_geo *geo,
        int i, height;
 
        for (height = head->height; height > level; height--) {
-               for (i = 0; i < geo->no_pairs; i++)
-                       if (keycmp(geo, node, i, key) <= 0)
-                               break;
+               i = getpos(geo, node, key);
 
-               if ((i == geo->no_pairs) || !bval(geo, node, i)) {
+               if ((i < 0) || !bval(geo, node, i)) {
                        /* right-most key is too large, update it */
                        /* FIXME: If the right-most key on higher levels is
                         * always zero, this wouldn't be necessary. */
@@ -466,7 +458,7 @@ static int btree_insert_level(struct btree_head *head, 
struct btree_geo *geo,
        /* two identical keys are not allowed */
        BUG_ON(pos < fill && keycmp(geo, node, pos, key) == 0);
 
-       if (fill == geo->no_pairs) {
+       if (fill < 0) {
                /* need to split node */
                unsigned long *new;
 
-- 
2.7.4