XArray: Permit storing 2-byte-aligned pointers

On m68k, statically allocated pointers may only be two-byte aligned.
This clashes with the XArray's method for tagging internal pointers.
Permit storing these pointers in single slots (ie not in multislots).

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

1 files changed, 30 insertions, 0 deletions

diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index dc02eff562b8..6e0212a60b08 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -1184,6 +1184,35 @@ static noinline void check_store_range(struct xarray *xa)
         }
 }
 
+static void check_align_1(struct xarray *xa, char *name)
+{
+        int i;
+        unsigned int id;
+        unsigned long index;
+        void *entry;
+
+        for (i = 0; i < 8; i++) {
+                id = 0;
+                XA_BUG_ON(xa, xa_alloc(xa, &id, UINT_MAX, name + i, GFP_KERNEL)
+                                != 0);
+                XA_BUG_ON(xa, id != i);
+        }
+        xa_for_each(xa, index, entry)
+                XA_BUG_ON(xa, xa_is_err(entry));
+        xa_destroy(xa);
+}
+
+static noinline void check_align(struct xarray *xa)
+{
+        char name[] = "Motorola 68000";
+
+        check_align_1(xa, name);
+        check_align_1(xa, name + 1);
+        check_align_1(xa, name + 2);
+        check_align_1(xa, name + 3);
+//      check_align_2(xa, name);
+}
+
 static LIST_HEAD(shadow_nodes);
 
 static void test_update_node(struct xa_node *node)
@@ -1333,6 +1362,7 @@ static int xarray_checks(void)
         check_create_range(&array);
         check_store_range(&array);
         check_store_iter(&array);
+        check_align(&xa0);
 
         check_workingset(&array, 0);
         check_workingset(&array, 64);