* Wei Yang <richard.weiyang@xxxxxxxxx> [240908 10:06]:
> In function mast_fill_bnode(), we first clear some fields of
> maple_big_node and set the 'type' unconditionally before return. This
> means we won't leverage any information in maple_big_node and it is safe
> to clear the whole structure.
>
> In maple_big_node, we define slot and padding/gap in a union. And based
> on current definition of MAPLE_BIG_NODE_SLOTS/GAPS, padding is always
> less than slot and part of the gap is overlapped by slot.
>
> For example on 64bit system:
>
> MAPLE_BIG_NODE_SLOT is 34
> MAPLE_BIG_NODE_GAP is 21
>
> With this knowledge, current code may clear some space by twice. And
> this could be avoid by clearing the structure as a whole.
>
> Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
> CC: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
>
> ---
> v2: correct the change log on clearing all maple_big_node currently
Thanks!
> ---
> lib/maple_tree.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index c3370c7449c2..b459fe1a3ebe 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -3134,10 +3134,7 @@ static inline void mast_fill_bnode(struct maple_subtree_state *mast,
> bool cp = true;
> unsigned char split;
>
> - memset(mast->bn->gap, 0, sizeof(unsigned long) * ARRAY_SIZE(mast->bn->gap));
> - memset(mast->bn->slot, 0, sizeof(unsigned long) * ARRAY_SIZE(mast->bn->slot));
> - memset(mast->bn->pivot, 0, sizeof(unsigned long) * ARRAY_SIZE(mast->bn->pivot));
> - mast->bn->b_end = 0;
> + memset(mast->bn, 0, sizeof(struct maple_big_node));
>
> if (mte_is_root(mas->node)) {
> cp = false;
> --
> 2.34.1
>
