patch-2.3.16 linux/mm/bigmem.c

• Lines: 72
• Date: Thu Aug 26 12:36:07 1999
• Orig file: v2.3.15/linux/mm/bigmem.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.15/linux/mm/bigmem.c linux/mm/bigmem.c
@@ -0,0 +1,71 @@
+/*
+ * BIGMEM common code and variables.
+ *
+ * (C) 1999 Andrea Arcangeli, SuSE GmbH, andrea@suse.de
+ *          Gerhard Wichert, Siemens AG, Gerhard.Wichert@pdb.siemens.de
+ */
+
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/bigmem.h>
+
+unsigned long bigmem_mapnr;
+int nr_free_bigpages = 0;
+
+struct page * prepare_bigmem_swapout(struct page * page)
+{
+	/* if this is a bigmem page so it can't be swapped out directly
+	   otherwise the b_data buffer addresses will break
+	   the lowlevel device drivers. */
+	if (PageBIGMEM(page)) {
+		unsigned long regular_page;
+		unsigned long vaddr;
+
+		regular_page = __get_free_page(GFP_ATOMIC);
+		if (!regular_page)
+			return NULL;
+
+		vaddr = kmap(page_address(page), KM_READ);
+		copy_page(regular_page, vaddr);
+		kunmap(vaddr, KM_READ);
+
+		/* ok, we can just forget about our bigmem page since 
+		   we stored its data into the new regular_page. */
+		__free_page(page);
+
+		page = MAP_NR(regular_page) + mem_map;
+	}
+	return page;
+}
+
+struct page * replace_with_bigmem(struct page * page)
+{
+	if (!PageBIGMEM(page) && nr_free_bigpages) {
+		unsigned long kaddr;
+
+		kaddr = __get_free_page(GFP_ATOMIC|GFP_BIGMEM);
+		if (kaddr) {
+			struct page * bigmem_page;
+
+			bigmem_page = MAP_NR(kaddr) + mem_map;
+			if (PageBIGMEM(bigmem_page)) {
+				unsigned long vaddr;
+
+				vaddr = kmap(kaddr, KM_WRITE);
+				copy_page(vaddr, page_address(page));
+				kunmap(vaddr, KM_WRITE);
+
+				/* Preserve the caching of the swap_entry. */
+				bigmem_page->offset = page->offset;
+
+				/* We can just forget the old page since 
+				   we stored its data into the new
+				   bigmem_page. */
+				__free_page(page);
+
+				page = bigmem_page;
+			}
+		}
+	}
+	return page;
+}