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

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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: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Peng Zhang 2023-05-24 11:12:45 +08:00 committed by Andrew Morton
parent 2e1da329b4
commit e6d1ffd611
1 changed files with 19 additions and 34 deletions
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53
lib/maple_tree.c
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@ -4202,49 +4202,34 @@ done:
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];
gap |= !mt_slot_locked(mas->tree, wr_mas->slots, offset);
gap |= !mt_slot_locked(mas->tree, wr_mas->slots, 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;
/* 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;
} 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. */
}
/* 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;
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);
mas_update_gap(mas);
/*
* 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;