On 10/23/24 9:20 PM, Wei Yang wrote:
On Wed, Aug 14, 2024 at 12:19:43PM -0400, Sidhartha Kumar wrote:
Users of mas_store_prealloc() enter this function with nodes already
preallocated. This means the store type must be already set. We can then
remove the call to mas_wr_store_type() and initialize the write state to
continue the partial walk that was done when determining the store type.
May I ask what is the partial walk here means?
It is the mas_wr_walk() in mas_wr_store_type() which is stopped because of it
is spanning write?
Yes, this is what I meant by the partial walk that's already been
started. It's the walk done by mas_wr_store_type().
I may lost some background, so the assumption here is mas_wr_store_type() has
already been invoked and the store type has been decided, right?
Ya users of mas_store_prealloc() should have already called
mas_preallocate() which does:
mas->store_type = mas_wr_store_type(&wr_mas);
request = mas_prealloc_calc(&wr_mas, entry);
to set the store type and allocate the nodes.
Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
---
lib/maple_tree.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 8c1a1a483395..73ce63d9c3a0 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -3979,9 +3979,6 @@ static inline void mas_wr_end_piv(struct ma_wr_state *wr_mas)
wr_mas->end_piv = wr_mas->pivots[wr_mas->offset_end];
else
wr_mas->end_piv = wr_mas->mas->max;
-
- if (!wr_mas->entry)
- mas_wr_extend_null(wr_mas);
}
static inline unsigned char mas_wr_new_end(struct ma_wr_state *wr_mas)
@@ -5532,8 +5529,19 @@ void mas_store_prealloc(struct ma_state *mas, void *entry)
{
MA_WR_STATE(wr_mas, mas, entry);
- mas_wr_prealloc_setup(&wr_mas);
- mas_wr_store_type(&wr_mas);
+ if (mas->store_type == wr_store_root) {
+ mas_wr_prealloc_setup(&wr_mas);
+ goto store;
+ }
+
+ mas_wr_walk_descend(&wr_mas);
This one does not descend the tree, just locate the offset in a node and
adjust min/max. So not look like to continue the partial walk to me.
+ if (mas->store_type != wr_spanning_store) {
+ /* set wr_mas->content to current slot */
+ wr_mas.content = mas_slot_locked(mas, wr_mas.slots, mas->offset);
+ mas_wr_end_piv(&wr_mas);
If not a spanning write, the previous walk should reach a leaf node, right?
Ya that's true.
I am not sure why we don't need to check extend null here. Because we have
already done it?
Ya we extend null in mas_wr_store_type() which has already been called
at this point.
/* At this point, we are at the leaf node that needs to be altered. */
mas_wr_end_piv(wr_mas);
if (!wr_mas->entry)
mas_wr_extend_null(wr_mas);
Thanks,
Sid
+ }
+
+store:
trace_ma_write(__func__, mas, 0, entry);
mas_wr_store_entry(&wr_mas);
MAS_WR_BUG_ON(&wr_mas, mas_is_err(mas));
--
2.46.0
