radix_tree: clean away saw_unset_tag leftovers

radix_tree_tag_get()'s BUG (when it sees a tag after saw_unset_tag) was
unsafe and removed in 2.6.34, but the pointless saw_unset_tag left behind.

Remove it now, and return 0 as soon as we see unset tag - we already rely
upon the root tag to be correct, returning 0 immediately if it's not set.

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 8 deletions

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index a2f9da59c197..d9df7454519c 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -576,7 +576,6 @@ int radix_tree_tag_get(struct radix_tree_root *root,
 {
         unsigned int height, shift;
         struct radix_tree_node *node;
-        int saw_unset_tag = 0;
 
         /* check the root's tag bit */
         if (!root_tag_get(root, tag))
@@ -603,15 +602,10 @@ int radix_tree_tag_get(struct radix_tree_root *root,
                         return 0;
 
                 offset = (index >> shift) & RADIX_TREE_MAP_MASK;
-
-                /*
-                 * This is just a debug check.  Later, we can bale as soon as
-                 * we see an unset tag.
-                 */
                 if (!tag_get(node, tag, offset))
-                        saw_unset_tag = 1;
+                        return 0;
                 if (height == 1)
-                        return !!tag_get(node, tag, offset);
+                        return 1;
                 node = rcu_dereference_raw(node->slots[offset]);
                 shift -= RADIX_TREE_MAP_SHIFT;
                 height--;