radix-tree: create node_tag_set()

Similar to node_tag_clear(), factor node_tag_set() out of
radix_tree_range_tag_if_tagged().

Link: http://lkml.kernel.org/r/1480369871-5271-51-git-send-email-mawilcox@linuxonhyperv.com
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 19 insertions, 22 deletions

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 8c5911eae5e2..a90a4371deb8 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -991,6 +991,22 @@ static void node_tag_clear(struct radix_tree_root *root,
                 root_tag_clear(root, tag);
 }
 
+static void node_tag_set(struct radix_tree_root *root,
+                                struct radix_tree_node *node,
+                                unsigned int tag, unsigned int offset)
+{
+        while (node) {
+                if (tag_get(node, tag, offset))
+                        return;
+                tag_set(node, tag, offset);
+                offset = node->offset;
+                node = node->parent;
+        }
+
+        if (!root_tag_get(root, tag))
+                root_tag_set(root, tag);
+}
+
 /**
  *      radix_tree_tag_clear - clear a tag on a radix tree node
  *      @root:          radix tree root
@@ -1229,7 +1245,7 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
                 unsigned long nr_to_tag,
                 unsigned int iftag, unsigned int settag)
 {
-        struct radix_tree_node *parent, *node, *child;
+        struct radix_tree_node *node, *child;
         unsigned long maxindex;
         unsigned long tagged = 0;
         unsigned long index = *first_indexp;
@@ -1264,22 +1280,8 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
                         continue;
                 }
 
-                /* tag the leaf */
                 tagged++;
-                tag_set(node, settag, offset);
-
-                /* walk back up the path tagging interior nodes */
-                parent = node;
-                for (;;) {
-                        offset = parent->offset;
-                        parent = parent->parent;
-                        if (!parent)
-                                break;
-                        /* stop if we find a node with the tag already set */
-                        if (tag_get(parent, settag, offset))
-                                break;
-                        tag_set(parent, settag, offset);
-                }
+                node_tag_set(root, node, settag, offset);
  next:
                 /* Go to next entry in node */
                 index = ((index >> node->shift) + 1) << node->shift;
@@ -1301,12 +1303,7 @@ unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
                 if (tagged >= nr_to_tag)
                         break;
         }
-        /*
-         * We need not to tag the root tag if there is no tag which is set with
-         * settag within the range from *first_indexp to last_index.
-         */
-        if (tagged > 0)
-                root_tag_set(root, settag);
+
         *first_indexp = index;
 
         return tagged;