XArray: Fix xa_alloc when id exceeds max

Specifying a starting ID greater than the maximum ID isn't something
attempted very often, but it should fail.  It was succeeding due to
xas_find_marked() returning the wrong error state, so add tests for
both xa_alloc() and xas_find_marked().

Fixes: b803b428 ("xarray: Add XArray iterators")
Signed-off-by: Matthew Wilcox <willy@infradead.org>

lib/test_xarray.c

@@ -633,6 +633,15 @@ static noinline void check_xa_alloc(void)
 				GFP_KERNEL) != -ENOSPC);
 	XA_BUG_ON(&xa0, id != 0xffffffffU);
 	xa_destroy(&xa0);
+
+	id = 10;
+	XA_BUG_ON(&xa0, xa_alloc(&xa0, &id, 5, xa_mk_index(id),
+				GFP_KERNEL) != -ENOSPC);
+	XA_BUG_ON(&xa0, xa_store_index(&xa0, 3, GFP_KERNEL) != 0);
+	XA_BUG_ON(&xa0, xa_alloc(&xa0, &id, 5, xa_mk_index(id),
+				GFP_KERNEL) != -ENOSPC);
+	xa_erase_index(&xa0, 3);
+	XA_BUG_ON(&xa0, !xa_empty(&xa0));
 }
 
 static noinline void __check_store_iter(struct xarray *xa, unsigned long start,
@@ -822,10 +831,34 @@ static noinline void check_find_2(struct xarray *xa)
 	xa_destroy(xa);
 }
 
+static noinline void check_find_3(struct xarray *xa)
+{
+	XA_STATE(xas, xa, 0);
+	unsigned long i, j, k;
+	void *entry;
+
+	for (i = 0; i < 100; i++) {
+		for (j = 0; j < 100; j++) {
+			for (k = 0; k < 100; k++) {
+				xas_set(&xas, j);
+				xas_for_each_marked(&xas, entry, k, XA_MARK_0)
+					;
+				if (j > k)
+					XA_BUG_ON(xa,
+						xas.xa_node != XAS_RESTART);
+			}
+		}
+		xa_store_index(xa, i, GFP_KERNEL);
+		xa_set_mark(xa, i, XA_MARK_0);
+	}
+	xa_destroy(xa);
+}
+
 static noinline void check_find(struct xarray *xa)
 {
 	check_find_1(xa);
 	check_find_2(xa);
+	check_find_3(xa);
 	check_multi_find(xa);
 	check_multi_find_2(xa);
 }

lib/xarray.c

@@ -1131,7 +1131,7 @@ void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
 		entry = xa_head(xas->xa);
 		xas->xa_node = NULL;
 		if (xas->xa_index > max_index(entry))
-			goto bounds;
+			goto out;
 		if (!xa_is_node(entry)) {
 			if (xa_marked(xas->xa, mark))
 				return entry;
@@ -1180,11 +1180,9 @@ void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
 	}
 
 out:
-	if (!max)
+	if (xas->xa_index > max)
 		goto max;
-bounds:
-	xas->xa_node = XAS_BOUNDS;
-	return NULL;
+	return set_bounds(xas);
 max:
 	xas->xa_node = XAS_RESTART;
 	return NULL;