XArray: Add private interface for workingset node deletion

Move the tricky bits of dealing with the XArray from the workingset
code to the XArray.  Make it clear in the documentation that this is a
private interface, and only export it for the benefit of the test suite.

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

diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index 6b336098fca712d3e14743b29f493ee235af89d8..29db4e16eb89ed819098f314f38aa40c01d566a3 100644 (file)
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -1286,6 +1286,8 @@ static inline bool xa_is_advanced(const void *entry)
  */
 typedef void (*xa_update_node_t)(struct xa_node *node);
 
+void xa_delete_node(struct xa_node *, xa_update_node_t);
+
 /*
  * The xa_state is opaque to its users.  It contains various different pieces
  * of state involved in the current operation on the XArray.  It should be

diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index 1122c4453c87dc1bf1c08d75dfe85347b7dce200..64ae07b1bcf4d3e6db7f8bfe5854b0c442d88e26 100644 (file)
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -1600,14 +1600,9 @@ static noinline void shadow_remove(struct xarray *xa)
        xa_lock(xa);
        while ((node = list_first_entry_or_null(&shadow_nodes,
                                        struct xa_node, private_list))) {
-               XA_STATE(xas, node->array, 0);
                XA_BUG_ON(xa, node->array != xa);
                list_del_init(&node->private_list);
-               xas.xa_node = xa_parent_locked(node->array, node);
-               xas.xa_offset = node->offset;
-               xas.xa_shift = node->shift + XA_CHUNK_SHIFT;
-               xas_set_update(&xas, test_update_node);
-               xas_store(&xas, NULL);
+               xa_delete_node(node, test_update_node);
        }
        xa_unlock(xa);
 }

diff --git a/lib/xarray.c b/lib/xarray.c
index e9e641d3c0c31b872cb0eedbfbd03179a595d8ea..1fa5c5658e638352c9ba9f91d22431ef6d9f3e2f 100644 (file)
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1973,6 +1973,29 @@ unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
 }
 EXPORT_SYMBOL(xa_extract);
 
+/**
+ * xa_delete_node() - Private interface for workingset code.
+ * @node: Node to be removed from the tree.
+ * @update: Function to call to update ancestor nodes.
+ *
+ * Context: xa_lock must be held on entry and will not be released.
+ */
+void xa_delete_node(struct xa_node *node, xa_update_node_t update)
+{
+       struct xa_state xas = {
+               .xa = node->array,
+               .xa_index = (unsigned long)node->offset <<
+                               (node->shift + XA_CHUNK_SHIFT),
+               .xa_shift = node->shift + XA_CHUNK_SHIFT,
+               .xa_offset = node->offset,
+               .xa_node = xa_parent_locked(node->array, node),
+               .xa_update = update,
+       };
+
+       xas_store(&xas, NULL);
+}
+EXPORT_SYMBOL_GPL(xa_delete_node);     /* For the benefit of the test suite */
+
 /**
  * xa_destroy() - Free all internal data structures.
  * @xa: XArray.

diff --git a/mm/workingset.c b/mm/workingset.c
index 92e66113a5779e6a68db8c8f90934fae36e7d39d..e185bfb8bd4ef8cca2666d5b66dc98f131784561 100644 (file)
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -519,12 +519,11 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
                                          void *arg) __must_hold(lru_lock)
 {
        struct xa_node *node = container_of(item, struct xa_node, private_list);
-       XA_STATE(xas, node->array, 0);
        struct address_space *mapping;
        int ret;
 
        /*
-        * Page cache insertions and deletions synchroneously maintain
+        * Page cache insertions and deletions synchronously maintain
         * the shadow node LRU under the i_pages lock and the
         * lru_lock.  Because the page cache tree is emptied before
         * the inode can be destroyed, holding the lru_lock pins any
@@ -559,15 +558,7 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
        if (WARN_ON_ONCE(node->count != node->nr_values))
                goto out_invalid;
        mapping->nrexceptional -= node->nr_values;
-       xas.xa_node = xa_parent_locked(&mapping->i_pages, node);
-       xas.xa_offset = node->offset;
-       xas.xa_shift = node->shift + XA_CHUNK_SHIFT;
-       xas_set_update(&xas, workingset_update_node);
-       /*
-        * We could store a shadow entry here which was the minimum of the
-        * shadow entries we were tracking ...
-        */
-       xas_store(&xas, NULL);
+       xa_delete_node(node, workingset_update_node);
        __inc_lruvec_slab_state(node, WORKINGSET_NODERECLAIM);
 
 out_invalid: