[PATCH 2/5] iova: drop dead cached_node / cached32_node infrastructure

[Rik van Riel <riel@surriel.com>]

From: Rik van Riel <riel@meta.com>

After the augmented-rbtree port, cached_node and cached32_node are still
maintained on every insert and delete but are never consulted on the
allocation path. Drop the fields and their helpers.

The one piece of useful work in __cached_rbnode_delete_update() was
resetting iovad->max32_alloc_size when an iova in the 32-bit range was
freed (so the next 32-bit alloc can retry). That logic is preserved by
moving it inline into remove_iova().

No external consumers reference the cached_node fields.

Assisted-by: Claude:claude-opus-4.7
Signed-off-by: Rik van Riel <riel@surriel.com>
---
 drivers/iommu/iova.c | 35 +++--------------------------------
 include/linux/iova.h |  2 --
 2 files changed, 3 insertions(+), 34 deletions(-)

diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
index 953188e296f0..c358ce981cae 100644
--- a/drivers/iommu/iova.c
+++ b/drivers/iommu/iova.c
@@ -57,8 +57,6 @@ init_iova_domain(struct iova_domain *iovad, unsigned long granule,
 
 	spin_lock_init(&iovad->iova_rbtree_lock);
 	iovad->rbroot = RB_ROOT;
-	iovad->cached_node = &iovad->anchor.node;
-	iovad->cached32_node = &iovad->anchor.node;
 	iovad->granule = granule;
 	iovad->start_pfn = start_pfn;
 	iovad->dma_32bit_pfn = 1UL << (32 - iova_shift(iovad));
@@ -71,34 +69,6 @@ init_iova_domain(struct iova_domain *iovad, unsigned long granule,
 }
 EXPORT_SYMBOL_GPL(init_iova_domain);
 
-static void
-__cached_rbnode_insert_update(struct iova_domain *iovad, struct iova *new)
-{
-	if (new->pfn_hi < iovad->dma_32bit_pfn)
-		iovad->cached32_node = &new->node;
-	else
-		iovad->cached_node = &new->node;
-}
-
-static void
-__cached_rbnode_delete_update(struct iova_domain *iovad, struct iova *free)
-{
-	struct iova *cached_iova;
-
-	cached_iova = to_iova(iovad->cached32_node);
-	if (free == cached_iova ||
-	    (free->pfn_hi < iovad->dma_32bit_pfn &&
-	     free->pfn_lo >= cached_iova->pfn_lo))
-		iovad->cached32_node = rb_next(&free->node);
-
-	if (free->pfn_lo < iovad->dma_32bit_pfn)
-		iovad->max32_alloc_size = iovad->dma_32bit_pfn;
-
-	cached_iova = to_iova(iovad->cached_node);
-	if (free->pfn_lo >= cached_iova->pfn_lo)
-		iovad->cached_node = rb_next(&free->node);
-}
-
 /* Insert the iova into domain rbtree by holding writer lock */
 static void
 iova_insert_rbtree(struct rb_root *root, struct iova *iova,
@@ -221,7 +191,6 @@ static int __alloc_and_insert_iova_range(struct iova_domain *iovad,
 	new->pfn_hi = new_pfn + size - 1;
 
 	iova_insert_rbtree(&iovad->rbroot, new, gap_node);
-	__cached_rbnode_insert_update(iovad, new);
 
 	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
 	return 0;
@@ -308,7 +277,9 @@ static void remove_iova(struct iova_domain *iovad, struct iova *iova)
 	struct iova *next_iova = NULL;
 
 	assert_spin_locked(&iovad->iova_rbtree_lock);
-	__cached_rbnode_delete_update(iovad, iova);
+
+	if (iova->pfn_lo < iovad->dma_32bit_pfn)
+		iovad->max32_alloc_size = iovad->dma_32bit_pfn;
 
 	next_node = rb_next(&iova->node);
 	if (next_node) {
diff --git a/include/linux/iova.h b/include/linux/iova.h
index 52635a72c5c5..3c4cc81e5182 100644
--- a/include/linux/iova.h
+++ b/include/linux/iova.h
@@ -30,8 +30,6 @@ struct iova_rcache;
 struct iova_domain {
 	spinlock_t	iova_rbtree_lock; /* Lock to protect update of rbtree */
 	struct rb_root	rbroot;		/* iova domain rbtree root */
-	struct rb_node	*cached_node;	/* Save last alloced node */
-	struct rb_node	*cached32_node; /* Save last 32-bit alloced node */
 	unsigned long	granule;	/* pfn granularity for this domain */
 	unsigned long	start_pfn;	/* Lower limit for this domain */
 	unsigned long	dma_32bit_pfn;
-- 
2.52.0