maple_tree: rework mtree_alloc_{range,rrange}()

Patch series "Clean ups for maple tree", v4.

Some clean ups, mainly to make the code of maple tree more concise.
This patchset has passed the self-test.


This patch (of 10):

Use mas_empty_area{_rev}() to refactor mtree_alloc_{range,rrange}()

Link: https://lkml.kernel.org/r/20230524031247.65949-2-zhangpeng.00@bytedance.comSigned-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/maple_tree.c

@@ -6493,31 +6493,33 @@ int mtree_alloc_range(struct maple_tree *mt, unsigned long *startp,
 {
 	int ret = 0;
 
-	MA_STATE(mas, mt, min, min);
+	MA_STATE(mas, mt, 0, 0);
 	if (!mt_is_alloc(mt))
 		return -EINVAL;
 
 	if (WARN_ON_ONCE(mt_is_reserved(entry)))
 		return -EINVAL;
 
-	if (min > max)
-		return -EINVAL;
-
-	if (max < size)
-		return -EINVAL;
-
-	if (!size)
-		return -EINVAL;
-
 	mtree_lock(mt);
 retry:
-	mas.offset = 0;
-	mas.index = min;
-	mas.last = max - size + 1;
-	ret = mas_alloc(&mas, entry, size, startp);
+	ret = mas_empty_area(&mas, min, max, size);
+	if (ret)
+		goto unlock;
+
+	mas_insert(&mas, entry);
+	/*
+	 * mas_nomem() may release the lock, causing the allocated area
+	 * to be unavailable, so try to allocate a free area again.
+	 */
 	if (mas_nomem(&mas, gfp))
 		goto retry;
 
+	if (mas_is_err(&mas))
+		ret = xa_err(mas.node);
+	else
+		*startp = mas.index;
+
+unlock:
 	mtree_unlock(mt);
 	return ret;
 }
@@ -6529,28 +6531,33 @@ int mtree_alloc_rrange(struct maple_tree *mt, unsigned long *startp,
 {
 	int ret = 0;
 
-	MA_STATE(mas, mt, min, max - size + 1);
+	MA_STATE(mas, mt, 0, 0);
 	if (!mt_is_alloc(mt))
 		return -EINVAL;
 
 	if (WARN_ON_ONCE(mt_is_reserved(entry)))
 		return -EINVAL;
 
-	if (min > max)
-		return -EINVAL;
-
-	if (max < size - 1)
-		return -EINVAL;
-
-	if (!size)
-		return -EINVAL;
-
 	mtree_lock(mt);
 retry:
-	ret = mas_rev_alloc(&mas, min, max, entry, size, startp);
+	ret = mas_empty_area_rev(&mas, min, max, size);
+	if (ret)
+		goto unlock;
+
+	mas_insert(&mas, entry);
+	/*
+	 * mas_nomem() may release the lock, causing the allocated area
+	 * to be unavailable, so try to allocate a free area again.
+	 */
 	if (mas_nomem(&mas, gfp))
 		goto retry;
 
+	if (mas_is_err(&mas))
+		ret = xa_err(mas.node);
+	else
+		*startp = mas.index;
+
+unlock:
 	mtree_unlock(mt);
 	return ret;
 }