XArray: Fix xa_erase of 2-byte aligned entries

xas_store() was interpreting the entry it found in the array as a node
entry if the bottom two bits had value 2.  That's only true if either
the entry is in the root node or in a non-leaf node.

Signed-off-by: Matthew Wilcox <willy@infradead.org>

diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index 52f8ecff8c0cc3306e4785141161acc81313477a..bc202d468a6b0817ad1ca9fd1e23c420f77aeb0c 100644 (file)
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -1355,6 +1355,20 @@ static void check_align_1(struct xarray *xa, char *name)
        xa_destroy(xa);
 }
 
+static void check_align_2(struct xarray *xa, char *name)
+{
+       int i;
+
+       XA_BUG_ON(xa, !xa_empty(xa));
+
+       for (i = 0; i < 8; i++) {
+               XA_BUG_ON(xa, xa_store(xa, 0, name + i, GFP_KERNEL) != NULL);
+               xa_erase(xa, 0);
+       }
+
+       XA_BUG_ON(xa, !xa_empty(xa));
+}
+
 static noinline void check_align(struct xarray *xa)
 {
        char name[] = "Motorola 68000";
@@ -1363,7 +1377,7 @@ static noinline void check_align(struct xarray *xa)
        check_align_1(xa, name + 1);
        check_align_1(xa, name + 2);
        check_align_1(xa, name + 3);
-//     check_align_2(xa, name);
+       check_align_2(xa, name);
 }
 
 static LIST_HEAD(shadow_nodes);

diff --git a/lib/xarray.c b/lib/xarray.c
index 3f10198f00b77cc149203a89c7b631bbcf1ba708..2cc3798672f7dcc790d9147f1ca9b7f2ed90cb02 100644 (file)
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -800,7 +800,7 @@ void *xas_store(struct xa_state *xas, void *entry)
                 * entry is set to NULL.
                 */
                rcu_assign_pointer(*slot, entry);
-               if (xa_is_node(next))
+               if (xa_is_node(next) && (!node || node->shift))
                        xas_free_nodes(xas, xa_to_node(next));
                if (!node)
                        break;