Re: + xarray-add-xas_split-fix.patch added to -mm tree

[Matthew Wilcox <willy@infradead.org>]

On Tue, Sep 08, 2020 at 11:06:44PM +0100, Matthew Wilcox wrote:
> On Fri, Sep 04, 2020 at 10:23:53AM -0700, akpm@linux-foundation.org wrote:
> > From: Andrew Morton <akpm@linux-foundation.org>
> > Subject: xarray-add-xas_split-fix
> 
> Can I ask you to add another -fix patch?

... updated to also fix the documentation.  Thanks, Mauro.

commit 71c3da6f580dc6ce98143d92da768c85638d4518
Author: Matthew Wilcox (Oracle) <willy@infradead.org>
Date:   Tue Sep 8 17:55:22 2020 -0400

    fix xarray split

diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index 16fe5adcac62..8262c3f05a5d 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -1524,6 +1524,9 @@ static void check_split_1(struct xarray *xa, unsigned long index,
 	}
 	XA_BUG_ON(xa, i != 1 << order);
 
+	xa_set_mark(xa, index, XA_MARK_0);
+	XA_BUG_ON(xa, !xa_get_mark(xa, index, XA_MARK_0));
+
 	xa_destroy(xa);
 }
 
diff --git a/lib/xarray.c b/lib/xarray.c
index ff3652657bd8..b573db455c43 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -973,10 +973,11 @@ static void node_set_marks(struct xa_node *node, unsigned int offset,
 	xa_mark_t mark = XA_MARK_0;
 
 	for (;;) {
-		if (marks & (1 << (__force unsigned int)mark))
+		if (marks & (1 << (__force unsigned int)mark)) {
 			node_set_mark(node, offset, mark);
-		if (child)
-			node_mark_all(child, mark);
+			if (child)
+				node_mark_all(child, mark);
+		}
 		if (mark == XA_MARK_MAX)
 			break;
 		mark_inc(mark);
@@ -984,8 +985,18 @@ static void node_set_marks(struct xa_node *node, unsigned int offset,
 }
 
 /**
- * Allocate memory for splitting an entry of @order size into the order
- * stored in the @xas.
+ * xas_split_alloc() - Allocate memory for splitting an entry.
+ * @xas: XArray operation state.
+ * @entry: New entry which will be stored in the array.
+ * @order: New entry order.
+ * @gfp: Memory allocation flags.
+ *
+ * This function should be called before calling xas_split().
+ * If necessary, it will allocate new nodes (and fill them with @entry)
+ * to prepare for the upcoming split of an entry of @order size into
+ * entries of the order stored in the @xas.
+ *
+ * Context: May sleep if @gfp flags permit.
  */
 void xas_split_alloc(struct xa_state *xas, void *entry, unsigned int order,
 		gfp_t gfp)