Commit e6d1ffd6 authored by Peng Zhang's avatar Peng Zhang Committed by Andrew Morton
Browse files

maple_tree: rework mas_wr_slot_store() to be cleaner and more efficient. 

Get whether the two gaps to be overwritten are empty to avoid calling
mas_update_gap() all the time.  Also clean up the code and add comments.

Link: https://lkml.kernel.org/r/20230524031247.65949-9-zhangpeng.00@bytedance.com


Signed-off-by: default avatarPeng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 2e1da329

lib/maple_tree.c

+19 −34
Original line number Diff line number Diff line
@@ -4202,49 +4202,34 @@ static inline bool mas_wr_node_store(struct ma_wr_state *wr_mas) 
static inline bool mas_wr_slot_store(struct ma_wr_state *wr_mas)

{

	struct ma_state *mas = wr_mas->mas;

	unsigned long lmax; /* Logical max. */

	unsigned char offset = mas->offset;

	bool gap = false;



	if ((wr_mas->r_max > mas->last) && ((wr_mas->r_min != mas->index) ||

				  (offset != wr_mas->node_end)))

	if (wr_mas->offset_end - offset != 1)

		return false;



	if (offset == wr_mas->node_end - 1)

		lmax = mas->max;

	else

		lmax = wr_mas->pivots[offset + 1];



	/* going to overwrite too many slots. */

	if (lmax < mas->last)

		return false;



	if (wr_mas->r_min == mas->index) {

		/* overwriting two or more ranges with one. */

		if (lmax == mas->last)

			return false;

	gap |= !mt_slot_locked(mas->tree, wr_mas->slots, offset);

	gap |= !mt_slot_locked(mas->tree, wr_mas->slots, offset + 1);



		/* Overwriting all of offset and a portion of offset + 1. */

	if (mas->index == wr_mas->r_min) {

		/* Overwriting the range and over a part of the next range. */

		rcu_assign_pointer(wr_mas->slots[offset], wr_mas->entry);

		wr_mas->pivots[offset] = mas->last;

		goto done;

	}



	/* Doesn't end on the next range end. */

	if (lmax != mas->last)

		return false;



	/* Overwriting a portion of offset and all of offset + 1 */

	if ((offset + 1 < mt_pivots[wr_mas->type]) &&

	    (wr_mas->entry || wr_mas->pivots[offset + 1]))

		wr_mas->pivots[offset + 1] = mas->last;



	} else {

		/* Overwriting a part of the range and over the next range */

		rcu_assign_pointer(wr_mas->slots[offset + 1], wr_mas->entry);

		wr_mas->pivots[offset] = mas->index - 1;

		mas->offset++; /* Keep mas accurate. */

	}



done:

	trace_ma_write(__func__, mas, 0, wr_mas->entry);

	/*

	 * Only update gap when the new entry is empty or there is an empty

	 * entry in the original two ranges.

	 */

	if (!wr_mas->entry || gap)

		mas_update_gap(mas);



	return true;

}
@@ -4391,7 +4376,7 @@ static inline void mas_wr_modify(struct ma_wr_state *wr_mas) 
	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))

	if (new_end == wr_mas->node_end && mas_wr_slot_store(wr_mas))

		return;

	else if (mas_wr_node_store(wr_mas))

		return;