* Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx> [230515 09:18]:
> Make the code for detecting spanning writes more concise.
>
> Signed-off-by: Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx>
> ---
> lib/maple_tree.c | 36 +++++++++---------------------------
> 1 file changed, 9 insertions(+), 27 deletions(-)
>
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index 43a25d3042c1b..fbb6efc40e576 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -3728,41 +3728,23 @@ static bool mas_is_span_wr(struct ma_wr_state *wr_mas)
> {
> unsigned long max;
> unsigned long last = wr_mas->mas->last;
> - unsigned long piv = wr_mas->r_max;
> enum maple_type type = wr_mas->type;
> void *entry = wr_mas->entry;
>
> - /* Contained in this pivot */
> - if (piv > last)
I test this first since it is far more likely than the rest of the cases
in this function. Most writes will land in a leaf node eventually, so
this will be true most of the time. I'd like to keep it as a fast path.
> + max = unlikely(ma_is_leaf(type)) ? wr_mas->mas->max : wr_mas->r_max;
Please expand this to multiple lines. It is better to be more clear
than compact lines of code.
> + if (last < max) {
> + /* Contained in this pivot or this leaf node */
> return false;
> -
> - max = wr_mas->mas->max;
> - if (unlikely(ma_is_leaf(type))) {
> - /* Fits in the node, but may span slots. */
> - if (last < max)
> - return false;
> -
> - /* Writes to the end of the node but not null. */
> - if ((last == max) && entry)
> - return false;
> -
> + } else if (last == max) {
> /*
> - * Writing ULONG_MAX is not a spanning write regardless of the
> - * value being written as long as the range fits in the node.
> + * The last entry of leaf node cannot be NULL unless it is the
> + * rightmost node (writing ULONG_MAX), otherwise it spans slots.
> + * If this is not leaf node, detect spanning store wr walk.
> */
> - if ((last == ULONG_MAX) && (last == max))
> - return false;
> - } else if (piv == last) {
> - if (entry)
> - return false;
> -
> - /* Detect spanning store wr walk */
> - if (last == ULONG_MAX)
> + if (entry || last == ULONG_MAX)
> return false;
> }
> -
> - trace_ma_write(__func__, wr_mas->mas, piv, entry);
> -
> + trace_ma_write(__func__, wr_mas->mas, wr_mas->r_max, entry);
> return true;
> }
>
> --
> 2.20.1
>
