From: Josef Bacik Date: Mon, 15 Oct 2012 17:43:18 +0000 (-0400) Subject: Btrfs: optimize leaf_space_used X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=41be1f3b40b87de33cd2e7463dce88596dbdccc4;p=openwrt%2Fstaging%2Fblogic.git Btrfs: optimize leaf_space_used This gets called at least 4 times for every level while adding an object, and it involves 3 kmapping calls, which on my box take about 5us a piece. So instead use a token, which brings us down to 1 kmap call and makes this function take 1/3 of the time per call. Thanks, Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index e8b32641ea90..e7bea1d5f75f 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -3298,14 +3298,21 @@ static noinline int split_node(struct btrfs_trans_handle *trans, */ static int leaf_space_used(struct extent_buffer *l, int start, int nr) { + struct btrfs_item *start_item; + struct btrfs_item *end_item; + struct btrfs_map_token token; int data_len; int nritems = btrfs_header_nritems(l); int end = min(nritems, start + nr) - 1; if (!nr) return 0; - data_len = btrfs_item_end_nr(l, start); - data_len = data_len - btrfs_item_offset_nr(l, end); + btrfs_init_map_token(&token); + start_item = btrfs_item_nr(l, start); + end_item = btrfs_item_nr(l, end); + data_len = btrfs_token_item_offset(l, start_item, &token) + + btrfs_token_item_size(l, start_item, &token); + data_len = data_len - btrfs_token_item_offset(l, end_item, &token); data_len += sizeof(struct btrfs_item) * nr; WARN_ON(data_len < 0); return data_len;