[PATCH 1/7] mm/sparse.c: Introduce new function fill_subsection_map()

[Baoquan He]

Wrap the codes filling subsection map in section_activate() into
fill_subsection_map(), this makes section_activate() cleaner and
easier to follow.

Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
---
 mm/sparse.c | 45 ++++++++++++++++++++++++++++++++++-----------
 1 file changed, 34 insertions(+), 11 deletions(-)

diff --git a/mm/sparse.c b/mm/sparse.c
index c184b69460b7..9ad741ccbeb6 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -788,24 +788,28 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
 		depopulate_section_memmap(pfn, nr_pages, altmap);
 }
 
-static struct page * __meminit section_activate(int nid, unsigned long pfn,
-		unsigned long nr_pages, struct vmem_altmap *altmap)
+/**
+ * fill_subsection_map - fill subsection map of a memory region
+ * @pfn - start pfn of the memory range
+ * @nr_pages - number of pfns to add in the region
+ *
+ * This clears the related subsection map inside one section, and only
+ * intended for hotplug.
+ *
+ * Return:
+ * * 0		- On success.
+ * * -EINVAL	- Invalid memory region.
+ * * -EEXIST	- Subsection map has been set.
+ */
+static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
 {
-	DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
 	struct mem_section *ms = __pfn_to_section(pfn);
-	struct mem_section_usage *usage = NULL;
+	DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
 	unsigned long *subsection_map;
-	struct page *memmap;
 	int rc = 0;
 
 	subsection_mask_set(map, pfn, nr_pages);
 
-	if (!ms->usage) {
-		usage = kzalloc(mem_section_usage_size(), GFP_KERNEL);
-		if (!usage)
-			return ERR_PTR(-ENOMEM);
-		ms->usage = usage;
-	}
 	subsection_map = &ms->usage->subsection_map[0];
 
 	if (bitmap_empty(map, SUBSECTIONS_PER_SECTION))
@@ -816,6 +820,25 @@ static struct page * __meminit section_activate(int nid, unsigned long pfn,
 		bitmap_or(subsection_map, map, subsection_map,
 				SUBSECTIONS_PER_SECTION);
 
+	return rc;
+}
+
+static struct page * __meminit section_activate(int nid, unsigned long pfn,
+		unsigned long nr_pages, struct vmem_altmap *altmap)
+{
+	struct mem_section *ms = __pfn_to_section(pfn);
+	struct mem_section_usage *usage = NULL;
+	struct page *memmap;
+	int rc = 0;
+
+	if (!ms->usage) {
+		usage = kzalloc(mem_section_usage_size(), GFP_KERNEL);
+		if (!usage)
+			return ERR_PTR(-ENOMEM);
+		ms->usage = usage;
+	}
+
+	rc = fill_subsection_map(pfn, nr_pages);
 	if (rc) {
 		if (usage)
 			ms->usage = NULL;
-- 
2.17.2