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maple_tree: add cp_is_new_root() helper

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Add a helper to do what is needed when the maple copy node contains a new
root node.  This is useful for future commits and is self-documenting
code.

[Liam.Howlett@oracle.com: remove warnings on older compilers]
  Link: https://lkml.kernel.org/r/malwmirqnpuxqkqrobcmzfkmmxipoyzwfs2nwc5fbpxlt2r2ej@wchmjtaljvw3
[akpm@linux-foundation.org: s/cp->slot[0]/&cp->slot[0]/, per Liam]
Link: https://lkml.kernel.org/r/20260130205935.2559335-22-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andrew Ballance <andrewjballance@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christian Kujau <lists@nerdbynature.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Liam R. Howlett
2026-01-30 15:59:26 -05:00
committed by Andrew Morton
parent 62e9d349af
commit b00a1804e6
1 changed files with 38 additions and 32 deletions
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70
lib/maple_tree.c
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@@ -3337,6 +3337,43 @@ static void mas_spanning_rebalance(struct ma_state *mas,
mas_spanning_rebalance_loop(mas, mast, count);
}
static inline bool cp_is_new_root(struct maple_copy *cp, struct ma_state *mas)
{
if (cp->min || cp->max != ULONG_MAX)
return false;
if (cp->d_count != 1) {
enum maple_type mt = maple_arange_64;
if (!mt_is_alloc(mas->tree))
mt = maple_range_64;
cp->data = cp->d_count;
cp->s_count = 0;
dst_setup(cp, mas, mt);
init_cp_src(cp);
node_copy(mas, cp->src[0].node, 0, cp->data, cp->max, maple_copy,
cp->dst[0].node, 0, mt);
node_finalise(cp->dst[0].node, mt, cp->end + 1);
/*
* Warning, see cp_leaf_init() comment and rcu_assign_pointer()
* documentation. Since this is a new root, there are no
* read-side operations that can view it until it is insert into
* the tree after an rcu_assign_pointer() call.
*/
ma_init_slot(&cp->slot[0], cp->dst[0].node, mt);
cp->height++;
}
WARN_ON_ONCE(cp->dst[0].node != mte_to_node(
mt_slot_locked(mas->tree, cp->slot, 0)));
cp->dst[0].node->parent = ma_parent_ptr(mas_tree_parent(mas));
mas->min = 0;
mas->max = ULONG_MAX;
mas->depth = 0;
mas->node = mas_root_locked(mas);
return true;
}
/*
* spanning_ascend() - See if a spanning store operation has to keep walking up
* the tree
@@ -3359,39 +3396,8 @@ static bool spanning_ascend(struct maple_copy *cp, struct ma_state *mas,
}
cp_dst_to_slots(cp, l_wr_mas->mas->min, r_wr_mas->mas->max, mas);
if (!cp->min && cp->max == ULONG_MAX) {
/* New root */
if (cp->d_count != 1) {
enum maple_type mt = maple_arange_64;
if (!mt_is_alloc(mas->tree))
mt = maple_range_64;
cp->data = cp->d_count;
cp->s_count = 0;
dst_setup(cp, mas, mt);
init_cp_src(cp);
node_copy(mas, cp->src[0].node, 0, cp->data, cp->max, maple_copy,
cp->dst[0].node, 0, mt);
node_finalise(cp->dst[0].node, mt, cp->end + 1);
/*
* Warning, see cp_leaf_init() comment and rcu_assign_pointer()
* documentation. Since this is a new root, there are no
* read-side operations that can view it until it is insert into
* the tree after an rcu_assign_pointer() call.
*/
ma_init_slot(&cp->slot[0], cp->dst[0].node, mt);
cp->height++;
}
WARN_ON_ONCE(cp->dst[0].node != mte_to_node(
mt_slot_locked(mas->tree, cp->slot, 0)));
cp->dst[0].node->parent = ma_parent_ptr(mas_tree_parent(mas));
mas->min = 0;
mas->max = ULONG_MAX;
mas->depth = 0;
mas->node = mas_root_locked(mas);
if (cp_is_new_root(cp, mas))
return false;
}
/* Converged and has a single destination */
if ((cp->d_count == 1) &&