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Date: Tue, 23 May 2023 14:00:14 -0400
From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
To: Peng Zhang <zhangpeng.00@...edance.com>
Cc: akpm@...ux-foundation.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, maple-tree@...ts.infradead.org
Subject: Re: [PATCH v3 09/10] maple_tree: Simplify and clean up
mas_wr_node_store()
* Peng Zhang <zhangpeng.00@...edance.com> [230522 01:07]:
> Simplify and clean up mas_wr_node_store(), remove unnecessary code.
>
> Signed-off-by: Peng Zhang <zhangpeng.00@...edance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> ---
> lib/maple_tree.c | 87 +++++++++++++++---------------------------------
> 1 file changed, 26 insertions(+), 61 deletions(-)
>
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index 1fc872f7683c..aa1472c45757 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -4075,52 +4075,27 @@ static inline int mas_wr_spanning_store(struct ma_wr_state *wr_mas)
> *
> * Return: True if stored, false otherwise
> */
> -static inline bool mas_wr_node_store(struct ma_wr_state *wr_mas)
> +static inline bool mas_wr_node_store(struct ma_wr_state *wr_mas,
> + unsigned char new_end)
> {
> struct ma_state *mas = wr_mas->mas;
> void __rcu **dst_slots;
> unsigned long *dst_pivots;
> - unsigned char dst_offset;
> - unsigned char new_end = wr_mas->node_end;
> - unsigned char offset;
> - unsigned char node_slots = mt_slots[wr_mas->type];
> + unsigned char dst_offset, offset_end = wr_mas->offset_end;
> struct maple_node reuse, *newnode;
> - unsigned char copy_size, max_piv = mt_pivots[wr_mas->type];
> + unsigned char copy_size, node_pivots = mt_pivots[wr_mas->type];
> bool in_rcu = mt_in_rcu(mas->tree);
>
> - offset = mas->offset;
> - if (mas->last == wr_mas->r_max) {
> - /* runs right to the end of the node */
> - if (mas->last == mas->max)
> - new_end = offset;
> - /* don't copy this offset */
> - wr_mas->offset_end++;
> - } else if (mas->last < wr_mas->r_max) {
> - /* new range ends in this range */
> - if (unlikely(wr_mas->r_max == ULONG_MAX))
> - mas_bulk_rebalance(mas, wr_mas->node_end, wr_mas->type);
> -
> - new_end++;
> - } else {
> - if (wr_mas->end_piv == mas->last)
> - wr_mas->offset_end++;
> -
> - new_end -= wr_mas->offset_end - offset - 1;
> - }
> -
> - /* new range starts within a range */
> - if (wr_mas->r_min < mas->index)
> - new_end++;
> -
> - /* Not enough room */
> - if (new_end >= node_slots)
> - return false;
> -
> - /* Not enough data. */
> + /* Check if there is enough data. The room is enough. */
> if (!mte_is_root(mas->node) && (new_end <= mt_min_slots[wr_mas->type]) &&
> !(mas->mas_flags & MA_STATE_BULK))
> return false;
>
> + if (mas->last == wr_mas->end_piv)
> + offset_end++; /* don't copy this offset */
> + else if (unlikely(wr_mas->r_max == ULONG_MAX))
> + mas_bulk_rebalance(mas, wr_mas->node_end, wr_mas->type);
> +
> /* set up node. */
> if (in_rcu) {
> mas_node_count(mas, 1);
> @@ -4137,47 +4112,36 @@ static inline bool mas_wr_node_store(struct ma_wr_state *wr_mas)
> dst_pivots = ma_pivots(newnode, wr_mas->type);
> dst_slots = ma_slots(newnode, wr_mas->type);
> /* Copy from start to insert point */
> - memcpy(dst_pivots, wr_mas->pivots, sizeof(unsigned long) * (offset + 1));
> - memcpy(dst_slots, wr_mas->slots, sizeof(void *) * (offset + 1));
> - dst_offset = offset;
> + memcpy(dst_pivots, wr_mas->pivots, sizeof(unsigned long) * mas->offset);
> + memcpy(dst_slots, wr_mas->slots, sizeof(void *) * mas->offset);
>
> /* Handle insert of new range starting after old range */
> if (wr_mas->r_min < mas->index) {
> - mas->offset++;
> - rcu_assign_pointer(dst_slots[dst_offset], wr_mas->content);
> - dst_pivots[dst_offset++] = mas->index - 1;
> + rcu_assign_pointer(dst_slots[mas->offset], wr_mas->content);
> + dst_pivots[mas->offset++] = mas->index - 1;
> }
>
> /* Store the new entry and range end. */
> - if (dst_offset < max_piv)
> - dst_pivots[dst_offset] = mas->last;
> - mas->offset = dst_offset;
> - rcu_assign_pointer(dst_slots[dst_offset], wr_mas->entry);
> + if (mas->offset < node_pivots)
> + dst_pivots[mas->offset] = mas->last;
> + rcu_assign_pointer(dst_slots[mas->offset], wr_mas->entry);
>
> /*
> * this range wrote to the end of the node or it overwrote the rest of
> * the data
> */
> - if (wr_mas->offset_end > wr_mas->node_end || mas->last >= mas->max) {
> - new_end = dst_offset;
> + if (offset_end > wr_mas->node_end)
> goto done;
> - }
>
> - dst_offset++;
> + dst_offset = mas->offset + 1;
> /* Copy to the end of node if necessary. */
> - copy_size = wr_mas->node_end - wr_mas->offset_end + 1;
> - memcpy(dst_slots + dst_offset, wr_mas->slots + wr_mas->offset_end,
> + copy_size = wr_mas->node_end - offset_end + 1;
> + memcpy(dst_slots + dst_offset, wr_mas->slots + offset_end,
> sizeof(void *) * copy_size);
> - if (dst_offset < max_piv) {
> - if (copy_size > max_piv - dst_offset)
> - copy_size = max_piv - dst_offset;
> -
> - memcpy(dst_pivots + dst_offset,
> - wr_mas->pivots + wr_mas->offset_end,
> - sizeof(unsigned long) * copy_size);
> - }
> + memcpy(dst_pivots + dst_offset, wr_mas->pivots + offset_end,
> + sizeof(unsigned long) * (copy_size - 1));
>
> - if ((wr_mas->node_end == node_slots - 1) && (new_end < node_slots - 1))
> + if (new_end < node_pivots)
> dst_pivots[new_end] = mas->max;
>
> done:
> @@ -4379,7 +4343,8 @@ static inline void mas_wr_modify(struct ma_wr_state *wr_mas)
>
> if (new_end == wr_mas->node_end && mas_wr_slot_store(wr_mas))
> return;
> - else if (mas_wr_node_store(wr_mas))
> +
> + if (mas_wr_node_store(wr_mas, new_end))
> return;
>
> if (mas_is_err(mas))
> --
> 2.20.1
>
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