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maple_tree: add mas_wr_new_end() to calculate new_end accurately 

The previous new_end calculation is inaccurate, because it assumes that
two new pivots must be added (this is inaccurate), and sometimes it will
miss the fast path and enter the slow path.  Add mas_wr_new_end() to
accurately calculate new_end to make the conditions for entering the fast
path more accurate.

Link: https://lkml.kernel.org/r/20230524031247.65949-7-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 11:12:43 +08:00 committed by Andrew Morton
parent 8c995a6314
commit c6fc9e4a5c
1 changed files with 23 additions and 11 deletions
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34
lib/maple_tree.c
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@ -4296,6 +4296,21 @@ static inline void mas_wr_extend_null(struct ma_wr_state *wr_mas)
}
}
static inline unsigned char mas_wr_new_end(struct ma_wr_state *wr_mas)
{
struct ma_state *mas = wr_mas->mas;
unsigned char new_end = wr_mas->node_end + 2;
new_end -= wr_mas->offset_end - mas->offset;
if (wr_mas->r_min == mas->index)
new_end--;
if (wr_mas->end_piv == mas->last)
new_end--;
return new_end;
}
static inline bool mas_wr_append(struct ma_wr_state *wr_mas)
{
unsigned char end = wr_mas->node_end;
@ -4351,9 +4366,8 @@ static void mas_wr_bnode(struct ma_wr_state *wr_mas)
static inline void mas_wr_modify(struct ma_wr_state *wr_mas)
{
unsigned char node_slots;
unsigned char node_size;
struct ma_state *mas = wr_mas->mas;
unsigned char new_end;
/* Direct replacement */
if (wr_mas->r_min == mas->index && wr_mas->r_max == mas->last) {
@ -4363,17 +4377,15 @@ static inline void mas_wr_modify(struct ma_wr_state *wr_mas)
return;
}
/* Attempt to append */
node_slots = mt_slots[wr_mas->type];
node_size = wr_mas->node_end - wr_mas->offset_end + mas->offset + 2;
if (mas->max == ULONG_MAX)
node_size++;
/* slot and node store will not fit, go to the slow path */
if (unlikely(node_size >= node_slots))
/*
* new_end exceeds the size of the maple node and cannot enter the fast
* path.
*/
new_end = mas_wr_new_end(wr_mas);
if (new_end >= mt_slots[wr_mas->type])
goto slow_path;
if (wr_mas->entry && (wr_mas->node_end < node_slots - 1) &&
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);