1 files changed, 32 insertions, 45 deletions

diff --git a/drivers/md/bcache/bset.c b/drivers/md/bcache/bset.c
index 8f07fa6e1739..08768796b543 100644
--- a/drivers/md/bcache/bset.c
+++ b/drivers/md/bcache/bset.c
@@ -347,22 +347,19 @@ EXPORT_SYMBOL(bch_btree_keys_alloc);
 void bch_btree_keys_init(struct btree_keys *b, const struct btree_keys_ops *ops,
 			 bool *expensive_debug_checks)
 {
-	unsigned int i;
-
 	b->ops = ops;
 	b->expensive_debug_checks = expensive_debug_checks;
 	b->nsets = 0;
 	b->last_set_unwritten = 0;
 
-	/* XXX: shouldn't be needed */
-	for (i = 0; i < MAX_BSETS; i++)
-		b->set[i].size = 0;
 	/*
-	 * Second loop starts at 1 because b->keys[0]->data is the memory we
-	 * allocated
+	 * struct btree_keys in embedded in struct btree, and struct
+	 * bset_tree is embedded into struct btree_keys. They are all
+	 * initialized as 0 by kzalloc() in mca_bucket_alloc(), and
+	 * b->set[0].data is allocated in bch_btree_keys_alloc(), so we
+	 * don't have to initiate b->set[].size and b->set[].data here
+	 * any more.
 	 */
-	for (i = 1; i < MAX_BSETS; i++)
-		b->set[i].data = NULL;
 }
 EXPORT_SYMBOL(bch_btree_keys_init);
 
@@ -887,12 +884,22 @@ unsigned int bch_btree_insert_key(struct btree_keys *b, struct bkey *k,
 	struct bset *i = bset_tree_last(b)->data;
 	struct bkey *m, *prev = NULL;
 	struct btree_iter iter;
+	struct bkey preceding_key_on_stack = ZERO_KEY;
+	struct bkey *preceding_key_p = &preceding_key_on_stack;
 
 	BUG_ON(b->ops->is_extents && !KEY_SIZE(k));
 
-	m = bch_btree_iter_init(b, &iter, b->ops->is_extents
-				? PRECEDING_KEY(&START_KEY(k))
-				: PRECEDING_KEY(k));
+	/*
+	 * If k has preceding key, preceding_key_p will be set to address
+	 *  of k's preceding key; otherwise preceding_key_p will be set
+	 * to NULL inside preceding_key().
+	 */
+	if (b->ops->is_extents)
+		preceding_key(&START_KEY(k), &preceding_key_p);
+	else
+		preceding_key(k, &preceding_key_p);
+
+	m = bch_btree_iter_init(b, &iter, preceding_key_p);
 
 	if (b->ops->insert_fixup(b, k, &iter, replace_key))
 		return status;
@@ -960,45 +967,25 @@ static struct bset_search_iter bset_search_tree(struct bset_tree *t,
 	unsigned int inorder, j, n = 1;
 
 	do {
-		/*
-		 * A bit trick here.
-		 * If p < t->size, (int)(p - t->size) is a minus value and
-		 * the most significant bit is set, right shifting 31 bits
-		 * gets 1. If p >= t->size, the most significant bit is
-		 * not set, right shifting 31 bits gets 0.
-		 * So the following 2 lines equals to
-		 *	if (p >= t->size)
-		 *		p = 0;
-		 * but a branch instruction is avoided.
-		 */
 		unsigned int p = n << 4;
 
-		p &= ((int) (p - t->size)) >> 31;
-
-		prefetch(&t->tree[p]);
+		if (p < t->size)
+			prefetch(&t->tree[p]);
 
 		j = n;
 		f = &t->tree[j];
 
-		/*
-		 * Similar bit trick, use subtract operation to avoid a branch
-		 * instruction.
-		 *
-		 * n = (f->mantissa > bfloat_mantissa())
-		 *	? j * 2
-		 *	: j * 2 + 1;
-		 *
-		 * We need to subtract 1 from f->mantissa for the sign bit trick
-		 * to work  - that's done in make_bfloat()
-		 */
-		if (likely(f->exponent != 127))
-			n = j * 2 + (((unsigned int)
-				      (f->mantissa -
-				       bfloat_mantissa(search, f))) >> 31);
-		else
-			n = (bkey_cmp(tree_to_bkey(t, j), search) > 0)
-				? j * 2
-				: j * 2 + 1;
+		if (likely(f->exponent != 127)) {
+			if (f->mantissa >= bfloat_mantissa(search, f))
+				n = j * 2;
+			else
+				n = j * 2 + 1;
+		} else {
+			if (bkey_cmp(tree_to_bkey(t, j), search) > 0)
+				n = j * 2;
+			else
+				n = j * 2 + 1;
+		}
 	} while (n < t->size);
 
 	inorder = to_inorder(j, t);