linux-kernel - [PATCH 05/19] radix-tree: Remove a use of root->height from delete

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Message-Id: <1460644642-30642-6-git-send-email-willy@linux.intel.com>
Date:	Thu, 14 Apr 2016 10:37:08 -0400
From:	Matthew Wilcox <willy@...ux.intel.com>
To:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Matthew Wilcox <willy@...ux.intel.com>, linux-mm@...ck.org,
	linux-fsdevel@...r.kernel.org,
	Konstantin Khlebnikov <koct9i@...il.com>,
	Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
	Jan Kara <jack@...e.com>, Neil Brown <neilb@...e.de>,
	Ross Zwisler <ross.zwisler@...ux.intel.com>
Subject: [PATCH 05/19] radix-tree: Remove a use of root->height from delete_node

If radix_tree_shrink returns whether it managed to shrink, then
__radix_tree_delete_node doesn't ned to query the tree to find out
whether it did any work or not.

Signed-off-by: Matthew Wilcox <willy@...ux.intel.com>
---
 lib/radix-tree.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index e963823..f85c8f5 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -1416,8 +1416,10 @@ unsigned long radix_tree_locate_item(struct radix_tree_root *root, void *item)
  *	radix_tree_shrink    -    shrink height of a radix tree to minimal
  *	@root		radix tree root
  */
-static inline void radix_tree_shrink(struct radix_tree_root *root)
+static inline bool radix_tree_shrink(struct radix_tree_root *root)
 {
+	bool shrunk = false;
+
 	/* try to shrink tree height */
 	while (root->height > 0) {
 		struct radix_tree_node *to_free = root->rnode;
@@ -1477,7 +1479,10 @@ static inline void radix_tree_shrink(struct radix_tree_root *root)
 			to_free->slots[0] = RADIX_TREE_RETRY;
 
 		radix_tree_node_free(to_free);
+		shrunk = true;
 	}
+
+	return shrunk;
 }
 
 /**
@@ -1500,11 +1505,8 @@ bool __radix_tree_delete_node(struct radix_tree_root *root,
 		struct radix_tree_node *parent;
 
 		if (node->count) {
-			if (node == indirect_to_ptr(root->rnode)) {
-				radix_tree_shrink(root);
-				if (root->height == 0)
-					deleted = true;
-			}
+			if (node == indirect_to_ptr(root->rnode))
+				deleted |= radix_tree_shrink(root);
 			return deleted;
 		}
 
-- 
2.8.0.rc3