Merge tag 'xarray-5.4' of git://git.infradead.org/users/willy/linux-dax

Pull XArray fixes from Matthew Wilcox:
 "These all fix various bugs, some of which people have tripped over and
  some of which have been caught by automatic tools"

* tag 'xarray-5.4' of git://git.infradead.org/users/willy/linux-dax:
  idr: Fix idr_alloc_u32 on 32-bit systems
  idr: Fix integer overflow in idr_for_each_entry
  radix tree: Remove radix_tree_iter_find
  idr: Fix idr_get_next_ul race with idr_remove
  XArray: Fix xas_next() with a single entry at 0

4 files changed, 40 insertions, 21 deletions

diff --git a/lib/idr.c b/lib/idr.c
index 66a374892482..c2cf2c52bbde 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -215,7 +215,7 @@ int idr_for_each(const struct idr *idr,
 EXPORT_SYMBOL(idr_for_each);
 
 /**
- * idr_get_next() - Find next populated entry.
+ * idr_get_next_ul() - Find next populated entry.
  * @idr: IDR handle.
  * @nextid: Pointer to an ID.
  *
@@ -224,7 +224,7 @@ EXPORT_SYMBOL(idr_for_each);
  * to the ID of the found value.  To use in a loop, the value pointed to by
  * nextid must be incremented by the user.
  */
-void *idr_get_next(struct idr *idr, int *nextid)
+void *idr_get_next_ul(struct idr *idr, unsigned long *nextid)
 {
 	struct radix_tree_iter iter;
 	void __rcu **slot;
@@ -245,18 +245,14 @@ void *idr_get_next(struct idr *idr, int *nextid)
 	}
 	if (!slot)
 		return NULL;
-	id = iter.index + base;
-
-	if (WARN_ON_ONCE(id > INT_MAX))
-		return NULL;
 
-	*nextid = id;
+	*nextid = iter.index + base;
 	return entry;
 }
-EXPORT_SYMBOL(idr_get_next);
+EXPORT_SYMBOL(idr_get_next_ul);
 
 /**
- * idr_get_next_ul() - Find next populated entry.
+ * idr_get_next() - Find next populated entry.
  * @idr: IDR handle.
  * @nextid: Pointer to an ID.
  *
@@ -265,22 +261,17 @@ EXPORT_SYMBOL(idr_get_next);
  * to the ID of the found value.  To use in a loop, the value pointed to by
  * nextid must be incremented by the user.
  */
-void *idr_get_next_ul(struct idr *idr, unsigned long *nextid)
+void *idr_get_next(struct idr *idr, int *nextid)
 {
-	struct radix_tree_iter iter;
-	void __rcu **slot;
-	unsigned long base = idr->idr_base;
 	unsigned long id = *nextid;
+	void *entry = idr_get_next_ul(idr, &id);
 
-	id = (id < base) ? 0 : id - base;
-	slot = radix_tree_iter_find(&idr->idr_rt, &iter, id);
-	if (!slot)
+	if (WARN_ON_ONCE(id > INT_MAX))
 		return NULL;
-
-	*nextid = iter.index + base;
-	return rcu_dereference_raw(*slot);
+	*nextid = id;
+	return entry;
 }
-EXPORT_SYMBOL(idr_get_next_ul);
+EXPORT_SYMBOL(idr_get_next);
 
 /**
  * idr_replace() - replace pointer for given ID.
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 18c1dfbb1765..c8fa1d274530 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -1529,7 +1529,7 @@ void __rcu **idr_get_free(struct radix_tree_root *root,
 			offset = radix_tree_find_next_bit(node, IDR_FREE,
 							offset + 1);
 			start = next_index(start, node, offset);
-			if (start > max)
+			if (start > max || start == 0)
 				return ERR_PTR(-ENOSPC);
 			while (offset == RADIX_TREE_MAP_SIZE) {
 				offset = node->offset + 1;
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index 9d631a7b6a70..7df4f7f395bf 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -1110,6 +1110,28 @@ static noinline void check_find_entry(struct xarray *xa)
 	XA_BUG_ON(xa, !xa_empty(xa));
 }
 
+static noinline void check_move_tiny(struct xarray *xa)
+{
+	XA_STATE(xas, xa, 0);
+
+	XA_BUG_ON(xa, !xa_empty(xa));
+	rcu_read_lock();
+	XA_BUG_ON(xa, xas_next(&xas) != NULL);
+	XA_BUG_ON(xa, xas_next(&xas) != NULL);
+	rcu_read_unlock();
+	xa_store_index(xa, 0, GFP_KERNEL);
+	rcu_read_lock();
+	xas_set(&xas, 0);
+	XA_BUG_ON(xa, xas_next(&xas) != xa_mk_index(0));
+	XA_BUG_ON(xa, xas_next(&xas) != NULL);
+	xas_set(&xas, 0);
+	XA_BUG_ON(xa, xas_prev(&xas) != xa_mk_index(0));
+	XA_BUG_ON(xa, xas_prev(&xas) != NULL);
+	rcu_read_unlock();
+	xa_erase_index(xa, 0);
+	XA_BUG_ON(xa, !xa_empty(xa));
+}
+
 static noinline void check_move_small(struct xarray *xa, unsigned long idx)
 {
 	XA_STATE(xas, xa, 0);
@@ -1217,6 +1239,8 @@ static noinline void check_move(struct xarray *xa)
 
 	xa_destroy(xa);
 
+	check_move_tiny(xa);
+
 	for (i = 0; i < 16; i++)
 		check_move_small(xa, 1UL << i);
 
diff --git a/lib/xarray.c b/lib/xarray.c
index 446b956c9188..1237c213f52b 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -994,6 +994,8 @@ void *__xas_prev(struct xa_state *xas)
 
 	if (!xas_frozen(xas->xa_node))
 		xas->xa_index--;
+	if (!xas->xa_node)
+		return set_bounds(xas);
 	if (xas_not_node(xas->xa_node))
 		return xas_load(xas);
 
@@ -1031,6 +1033,8 @@ void *__xas_next(struct xa_state *xas)
 
 	if (!xas_frozen(xas->xa_node))
 		xas->xa_index++;
+	if (!xas->xa_node)
+		return set_bounds(xas);
 	if (xas_not_node(xas->xa_node))
 		return xas_load(xas);