Commit 526f36f3 authored by Dev Jain's avatar Dev Jain Committed by Andrew Morton
Browse files

maple tree: add some comments 

Add comments explaining the fields for maple_metadata, since "end" is
ambiguous and "gap" can be confused as the largest gap, whereas it is
actually the offset of the largest gap.

Add comment for mas_ascend() to explain, whose min and max we are trying
to find.  Explain that, for example, if we are already on offset zero,
then the parent min is mas->min, otherwise we need to walk up to find the
implied pivot min.

Link: https://lkml.kernel.org/r/20250703063338.51509-1-dev.jain@arm.com


Signed-off-by: default avatarDev Jain <dev.jain@arm.com>
Reviewed-by: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 8aa2c0bf

include/linux/maple_tree.h

+2 −2
Original line number Diff line number Diff line
@@ -75,8 +75,8 @@ 
 * searching for gaps or any other code that needs to find the end of the data.

 */

struct maple_metadata {

	unsigned char end;

	unsigned char gap;

	unsigned char end;	/* end of data */

	unsigned char gap;	/* offset of largest gap */

};



/*

lib/maple_tree.c

+7 −1
Original line number Diff line number Diff line
@@ -1053,7 +1053,7 @@ static inline void mte_set_gap(const struct maple_enode *mn, 
 * mas_ascend() - Walk up a level of the tree.

 * @mas: The maple state

 *

 * Sets the @mas->max and @mas->min to the correct values when walking up.  This

 * Sets the @mas->max and @mas->min for the parent node of mas->node.  This

 * may cause several levels of walking up to find the correct min and max.

 * May find a dead node which will cause a premature return.

 * Return: 1 on dead node, 0 otherwise
@@ -1098,6 +1098,12 @@ static int mas_ascend(struct ma_state *mas) 


	min = 0;

	max = ULONG_MAX;



	/*

	 * !mas->offset implies that parent node min == mas->min.

	 * mas->offset > 0 implies that we need to walk up to find the

	 * implied pivot min.

	 */

	if (!mas->offset) {

		min = mas->min;

		set_min = true;