Merge tag 'xarray-5.18' of git://git.infradead.org/users/willy/xarray

Pull XArray updates from Matthew Wilcox:

 - Documentation update

 - Fix test-suite build after move of bitmap.h

 - Fix xas_create_range() when a large entry is already present

 - Fix xas_split() of a shadow entry

* tag 'xarray-5.18' of git://git.infradead.org/users/willy/xarray:
  XArray: Update the LRU list in xas_split()
  XArray: Fix xas_create_range() when multi-order entry present
  XArray: Include bitmap.h from xarray.h
  XArray: Document the locking requirement for the xa_state

4 files changed, 36 insertions, 5 deletions

diff --git a/Documentation/core-api/xarray.rst b/Documentation/core-api/xarray.rst
index a137a0e6d068..77e0ece2b1d6 100644
--- a/Documentation/core-api/xarray.rst
+++ b/Documentation/core-api/xarray.rst
@@ -315,11 +315,15 @@ indeed the normal API is implemented in terms of the advanced API.  The
 advanced API is only available to modules with a GPL-compatible license.
 
 The advanced API is based around the xa_state.  This is an opaque data
-structure which you declare on the stack using the XA_STATE()
-macro.  This macro initialises the xa_state ready to start walking
-around the XArray.  It is used as a cursor to maintain the position
-in the XArray and let you compose various operations together without
-having to restart from the top every time.
+structure which you declare on the stack using the XA_STATE() macro.
+This macro initialises the xa_state ready to start walking around the
+XArray.  It is used as a cursor to maintain the position in the XArray
+and let you compose various operations together without having to restart
+from the top every time.  The contents of the xa_state are protected by
+the rcu_read_lock() or the xas_lock().  If you need to drop whichever of
+those locks is protecting your state and tree, you must call xas_pause()
+so that future calls do not rely on the parts of the state which were
+left unprotected.
 
 The xa_state is also used to store errors.  You can call
 xas_error() to retrieve the error.  All operations check whether
diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index bb52b786be1b..72feab5ea8d4 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -9,6 +9,7 @@
  * See Documentation/core-api/xarray.rst for how to use the XArray.
  */
 
+#include <linux/bitmap.h>
 #include <linux/bug.h>
 #include <linux/compiler.h>
 #include <linux/gfp.h>
diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index 8b1c318189ce..e77d4856442c 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -1463,6 +1463,25 @@ unlock:
 	XA_BUG_ON(xa, !xa_empty(xa));
 }
 
+static noinline void check_create_range_5(struct xarray *xa,
+		unsigned long index, unsigned int order)
+{
+	XA_STATE_ORDER(xas, xa, index, order);
+	unsigned int i;
+
+	xa_store_order(xa, index, order, xa_mk_index(index), GFP_KERNEL);
+
+	for (i = 0; i < order + 10; i++) {
+		do {
+			xas_lock(&xas);
+			xas_create_range(&xas);
+			xas_unlock(&xas);
+		} while (xas_nomem(&xas, GFP_KERNEL));
+	}
+
+	xa_destroy(xa);
+}
+
 static noinline void check_create_range(struct xarray *xa)
 {
 	unsigned int order;
@@ -1490,6 +1509,9 @@ static noinline void check_create_range(struct xarray *xa)
 		check_create_range_4(xa, (3U << order) + 1, order);
 		check_create_range_4(xa, (3U << order) - 1, order);
 		check_create_range_4(xa, (1U << 24) + 1, order);
+
+		check_create_range_5(xa, 0, order);
+		check_create_range_5(xa, (1U << order), order);
 	}
 
 	check_create_range_3();
diff --git a/lib/xarray.c b/lib/xarray.c
index b95e92598b9c..4acc88ea7c21 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -722,6 +722,8 @@ void xas_create_range(struct xa_state *xas)
 
 		for (;;) {
 			struct xa_node *node = xas->xa_node;
+			if (node->shift >= shift)
+				break;
 			xas->xa_node = xa_parent_locked(xas->xa, node);
 			xas->xa_offset = node->offset - 1;
 			if (node->offset != 0)
@@ -1079,6 +1081,7 @@ void xas_split(struct xa_state *xas, void *entry, unsigned int order)
 					xa_mk_node(child));
 			if (xa_is_value(curr))
 				values--;
+			xas_update(xas, child);
 		} else {
 			unsigned int canon = offset - xas->xa_sibs;
 
@@ -1093,6 +1096,7 @@ void xas_split(struct xa_state *xas, void *entry, unsigned int order)
 	} while (offset-- > xas->xa_offset);
 
 	node->nr_values += values;
+	xas_update(xas, node);
 }
 EXPORT_SYMBOL_GPL(xas_split);
 #endif