[RFC 09/16] mm/cma: introduce cma_total_pages() for future use

[Joonsoo Kim <iamjoonsoo.kim@lge.com>]

In the following patches, total reserved page count is needed to
initialize ZONE_CMA. This is the preparation step for that.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
 include/linux/cma.h |    9 +++++++++
 mm/cma.c            |   17 +++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/include/linux/cma.h b/include/linux/cma.h
index a93438b..aeaea90 100644
--- a/include/linux/cma.h
+++ b/include/linux/cma.h
@@ -15,6 +15,9 @@
 
 struct cma;
 
+#ifdef CONFIG_CMA
+extern unsigned long cma_total_pages(unsigned long node_start_pfn,
+				unsigned long node_end_pfn);
 extern phys_addr_t cma_get_base(struct cma *cma);
 extern unsigned long cma_get_size(struct cma *cma);
 
@@ -27,4 +30,10 @@ extern int cma_init_reserved_mem(phys_addr_t base,
 					struct cma **res_cma);
 extern struct page *cma_alloc(struct cma *cma, int count, unsigned int align);
 extern bool cma_release(struct cma *cma, struct page *pages, int count);
+
+#else
+static inline unsigned long cma_total_pages(unsigned long node_start_pfn,
+				unsigned long node_end_pfn) { return 0; }
+
+#endif /* CONFIG_CMA */
 #endif
diff --git a/mm/cma.c b/mm/cma.c
index c35ceef..f817b91 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -40,6 +40,23 @@ struct cma cma_areas[MAX_CMA_AREAS];
 unsigned cma_area_count;
 static DEFINE_MUTEX(cma_mutex);
 
+unsigned long cma_total_pages(unsigned long node_start_pfn,
+				unsigned long node_end_pfn)
+{
+	int i;
+	unsigned long total_pages = 0;
+
+	for (i = 0; i < cma_area_count; i++) {
+		struct cma *cma = &cma_areas[i];
+
+		if (node_start_pfn <= cma->base_pfn &&
+			cma->base_pfn < node_end_pfn)
+			total_pages += cma->count;
+	}
+
+	return total_pages;
+}
+
 phys_addr_t cma_get_base(struct cma *cma)
 {
 	return PFN_PHYS(cma->base_pfn);
-- 
1.7.9.5

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