The foreach_order_pgoff() helper takes advantage of the ability to
insert multi-order entries into a radix. It is currently used by
devm_memremap_pages() to minimize the number of entries in the pgmap
radix. Instead of dividing a range by a constant power-of-2 sized unit
and inserting an entry for each unit, it determines the maximum
power-of-2 sized entry (subject to alignment offset) that can be
inserted at each iteration.
Up-level this helper so it can be used for populating other radix
instances. For example asynchronous-memmap-initialization-thread lookups
arriving in a follow on change.
Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
include/linux/memremap.h | 25 +++++++++++++++++++++++++
kernel/memremap.c | 25 -------------------------
2 files changed, 25 insertions(+), 25 deletions(-)
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index bfdc7363b13b..bff314de3f55 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -126,6 +126,31 @@ struct dev_pagemap {
enum memory_type type;
};
+static inline unsigned long order_at(struct resource *res, unsigned long pgoff)
+{
+ unsigned long phys_pgoff = PHYS_PFN(res->start) + pgoff;
+ unsigned long nr_pages, mask;
+
+ nr_pages = PHYS_PFN(resource_size(res));
+ if (nr_pages == pgoff)
+ return ULONG_MAX;
+
+ /*
+ * What is the largest aligned power-of-2 range available from
+ * this resource pgoff to the end of the resource range,
+ * considering the alignment of the current pgoff?
+ */
+ mask = phys_pgoff | rounddown_pow_of_two(nr_pages - pgoff);
+ if (!mask)
+ return ULONG_MAX;
+
+ return find_first_bit(&mask, BITS_PER_LONG);
+}
+
+#define foreach_order_pgoff(res, order, pgoff) \
+ for (pgoff = 0, order = order_at((res), pgoff); order < ULONG_MAX; \
+ pgoff += 1UL << order, order = order_at((res), pgoff))
+
#ifdef CONFIG_ZONE_DEVICE
void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap,
void (*kill)(struct percpu_ref *));
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 85e4a7c576b2..fc2f28033460 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -16,31 +16,6 @@ static RADIX_TREE(pgmap_radix, GFP_KERNEL);
#define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1)
#define SECTION_SIZE (1UL << PA_SECTION_SHIFT)
-static unsigned long order_at(struct resource *res, unsigned long pgoff)
-{
- unsigned long phys_pgoff = PHYS_PFN(res->start) + pgoff;
- unsigned long nr_pages, mask;
-
- nr_pages = PHYS_PFN(resource_size(res));
- if (nr_pages == pgoff)
- return ULONG_MAX;
-
- /*
- * What is the largest aligned power-of-2 range available from
- * this resource pgoff to the end of the resource range,
- * considering the alignment of the current pgoff?
- */
- mask = phys_pgoff | rounddown_pow_of_two(nr_pages - pgoff);
- if (!mask)
- return ULONG_MAX;
-
- return find_first_bit(&mask, BITS_PER_LONG);
-}
-
-#define foreach_order_pgoff(res, order, pgoff) \
- for (pgoff = 0, order = order_at((res), pgoff); order < ULONG_MAX; \
- pgoff += 1UL << order, order = order_at((res), pgoff))
-
#if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
int device_private_entry_fault(struct vm_area_struct *vma,
unsigned long addr,
