Btrfs devel - Sep 2013 - [PATCH] Btrfs: more efficient inode tree replace operation

Instead of removing the current inode from the red black tree
and then add the new one, just use the red black tree replace
operation, which is more efficient.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
---
 fs/btrfs/inode.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 26992ee..aa22926 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4688,11 +4688,11 @@ static void inode_tree_add(struct inode *inode)
 	struct btrfs_inode *entry;
 	struct rb_node **p;
 	struct rb_node *parent;
+	struct rb_node *new = &BTRFS_I(inode)->rb_node;
 	u64 ino = btrfs_ino(inode);
 
 	if (inode_unhashed(inode))
 		return;
-again:
 	parent = NULL;
 	spin_lock(&root->inode_lock);
 	p = &root->inode_tree.rb_node;
@@ -4707,14 +4707,14 @@ again:
 		else {
 			WARN_ON(!(entry->vfs_inode.i_state &
 				  (I_WILL_FREE | I_FREEING)));
-			rb_erase(parent, &root->inode_tree);
+			rb_replace_node(parent, new, &root->inode_tree);
 			RB_CLEAR_NODE(parent);
 			spin_unlock(&root->inode_lock);
-			goto again;
+			return;
 		}
 	}
-	rb_link_node(&BTRFS_I(inode)->rb_node, parent, p);
-	rb_insert_color(&BTRFS_I(inode)->rb_node, &root->inode_tree);
+	rb_link_node(new, parent, p);
+	rb_insert_color(new, &root->inode_tree);
 	spin_unlock(&root->inode_lock);
 }
 
-- 
1.7.9.5

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On Mon, Sep 02, 2013 at 12:19:13PM +0100, Filipe David Borba Manana
wrote:
> Instead of removing the current inode from the red black tree
> and then add the new one, just use the red black tree replace
> operation, which is more efficient.
Yup, this looks correct to me.

Reviewed-by: Zach Brown <zab@redhat.com>

- z
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