* Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx> [230517 04:59]:
> Add comment for mas_wr_append(), move mas_update_gap() into
> mas_wr_append(), and other cleanups to make mas_wr_modify() cleaner.
>
> Signed-off-by: Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx>
> ---
> lib/maple_tree.c | 33 ++++++++++++++++++++-------------
> 1 file changed, 20 insertions(+), 13 deletions(-)
>
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index 3b9d227f3d7d..bbe4c6f2858c 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -4308,6 +4308,12 @@ static inline unsigned char mas_wr_new_end(struct ma_wr_state *wr_mas)
> return new_end;
> }
>
> +/*
> + * mas_wr_append: Attempt to append
> + * @wr_mas: the maple write state
> + *
> + * Return: True if appended, false otherwise
> + */
> static inline bool mas_wr_append(struct ma_wr_state *wr_mas)
> {
> unsigned char end = wr_mas->node_end;
> @@ -4315,7 +4321,11 @@ static inline bool mas_wr_append(struct ma_wr_state *wr_mas)
> struct ma_state *mas = wr_mas->mas;
> unsigned char node_pivots = mt_pivots[wr_mas->type];
>
> + if (!(mas->offset == wr_mas->node_end))
> + return false;
> +
> if ((mas->index != wr_mas->r_min) && (mas->last == wr_mas->r_max)) {
> + /* Append to end of range */
> if (new_end < node_pivots)
> wr_mas->pivots[new_end] = wr_mas->pivots[end];
>
> @@ -4323,13 +4333,10 @@ static inline bool mas_wr_append(struct ma_wr_state *wr_mas)
> ma_set_meta(wr_mas->node, maple_leaf_64, 0, new_end);
>
> rcu_assign_pointer(wr_mas->slots[new_end], wr_mas->entry);
> - mas->offset = new_end;
> wr_mas->pivots[end] = mas->index - 1;
> -
> - return true;
> - }
> -
> - if ((mas->index == wr_mas->r_min) && (mas->last < wr_mas->r_max)) {
> + mas->offset = new_end;
> + } else if ((mas->index == wr_mas->r_min) && (mas->last < wr_mas->r_max)) {
> + /* Append to start of range */
> if (new_end < node_pivots)
> wr_mas->pivots[new_end] = wr_mas->pivots[end];
>
> @@ -4339,10 +4346,13 @@ static inline bool mas_wr_append(struct ma_wr_state *wr_mas)
>
> wr_mas->pivots[end] = mas->last;
> rcu_assign_pointer(wr_mas->slots[end], wr_mas->entry);
> - return true;
> + } else {
> + return false;
I don't think we can get here with your changes, what do you think? If
so, we can move the metadata setting to the outside of the if/else. I
checked by adding a BUG_ON() and the test code never gets here.
My thinking is, we know offset == node_end and new_end == node_end + 1..
so we must be inserting into the last slot and only adding one entry.
> }
>
> - return false;
> + if (!wr_mas->content || !wr_mas->entry)
> + mas_update_gap(mas);
> + return true;
> }
>
> /*
> @@ -4382,12 +4392,9 @@ static inline void mas_wr_modify(struct ma_wr_state *wr_mas)
> if (new_end >= mt_slots[wr_mas->type])
> goto slow_path;
>
> - if (wr_mas->entry && (wr_mas->node_end < mt_slots[wr_mas->type] - 1) &&
> - (mas->offset == wr_mas->node_end) && mas_wr_append(wr_mas)) {
> - if (!wr_mas->content || !wr_mas->entry)
> - mas_update_gap(mas);
> + /* Attempt to append */
> + if (new_end == wr_mas->node_end + 1 && mas_wr_append(wr_mas))
> return;
> - }
>
> if ((wr_mas->offset_end - mas->offset <= 1) && mas_wr_slot_store(wr_mas))
> return;
> --
> 2.20.1
>
