From: Liam R. Howlett <Liam.Howlett@oracle.com>
Date: Thu, 21 Apr 2022 00:37:48 +0000 (-0400)
Subject: maple_tree: Add preallocation support
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=52b644111e699d183ad4bc0fa961e572f143f79c;p=users%2Fjedix%2Flinux-maple.git

maple_tree: Add preallocation support

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---

diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
index 8f4d87129a3e..ded42d306287 100644
--- a/include/linux/maple_tree.h
+++ b/include/linux/maple_tree.h
@@ -454,8 +454,10 @@ void *mas_walk(struct ma_state *mas);
 void *mas_store(struct ma_state *mas, void *entry);
 void *mas_erase(struct ma_state *mas);
 int mas_store_gfp(struct ma_state *mas, void *entry, gfp_t gfp);
+void mas_store_prealloc(struct ma_state *mas, void *entry);
 void *mas_find(struct ma_state *mas, unsigned long max);
 void *mas_find_rev(struct ma_state *mas, unsigned long min);
+int mas_preallocate(struct ma_state *mas, void *entry, gfp_t gfp);
 
 bool mas_nomem(struct ma_state *mas, gfp_t gfp);
 void mas_pause(struct ma_state *mas);
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index d6a10216521e..c955cdef79be 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -5548,6 +5548,44 @@ retry:
 	return 0;
 }
 
+/**
+ * mas_store_prealloc() - Store a value into the tree using memeory
+ * preallocated in the maple state.
+ * @mas: The maple state
+ * @entry: The entry to store.
+ */
+void mas_store_prealloc(struct ma_state *mas, void *entry)
+{
+	MA_WR_STATE(wr_mas, mas, entry);
+
+	mas_wr_store_setup(&wr_mas);
+	trace_ma_write(__func__, mas, 0, entry);
+	mas_wr_store_entry(&wr_mas);
+	BUG_ON(mas_is_err(mas));
+	mas_destroy(mas);
+}
+
+/**
+ * mas_preallocate() - Preallocate enough nodes for a store operation
+ * @mas: The maple state
+ * @entry: The entry that will be stored
+ *
+ * Return: 0 on success, -ENOMEM if memory could not be allocated.
+ */
+int mas_preallocate(struct ma_state *mas, void *entry, gfp_t gfp)
+{
+
+	mas_set_alloc_req(mas, 1 + mas_mt_height(mas) * 3);
+	mas_alloc_nodes(mas, gfp);
+	if (likely(mas->node != MA_ERROR(-ENOMEM)))
+		return 0;
+
+	mas_set_alloc_req(mas, 0);
+	mas_destroy(mas);
+	mas->node = MAS_START;
+	return -ENOMEM;
+}
+
 /*
  * mas_expected_entries() - Set the expected number of entries that will be inserted.
  * @mas: The maple state