XArray: Fix xa_for_each with a single element at 0
The following sequence of calls would result in an infinite loop in
xa_find_after():
xa_store(xa, 0, x, GFP_KERNEL);
index = 0;
xa_for_each(xa, entry, index, ULONG_MAX, XA_PRESENT) { }
xa_find_after() was confusing the situation where we found no entry in
the tree with finding a multiorder entry, so it would look for the
successor entry forever. Just check for this case explicitly. Includes
a few new checks in the test suite to be sure this doesn't reappear.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
diff --git a/lib/xarray.c b/lib/xarray.c
index 8b176f0..c991ff4 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1829,6 +1829,8 @@ void *xa_find_after(struct xarray *xa, unsigned long *indexp,
entry = xas_find_marked(&xas, max, filter);
else
entry = xas_find(&xas, max);
+ if (xas.xa_node == XAS_BOUNDS)
+ break;
if (xas.xa_shift) {
if (xas.xa_index & ((1UL << xas.xa_shift) - 1))
continue;