patch-1.3.57 linux/mm/swap_state.c

• Lines: 112
• Date: Tue Jan 9 20:41:31 1996
• Orig file: v1.3.56/linux/mm/swap_state.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.56/linux/mm/swap_state.c linux/mm/swap_state.c
@@ -0,0 +1,111 @@
+/*
+ *  linux/mm/swap_state.c
+ *
+ *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
+ *  Swap reorganised 29.12.95, Stephen Tweedie
+ */
+
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/head.h>
+#include <linux/kernel.h>
+#include <linux/kernel_stat.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/stat.h>
+#include <linux/swap.h>
+#include <linux/fs.h>
+#include <linux/swapctl.h>
+
+#include <asm/dma.h>
+#include <asm/system.h> /* for cli()/sti() */
+#include <asm/segment.h> /* for memcpy_to/fromfs */
+#include <asm/bitops.h>
+#include <asm/pgtable.h>
+
+/*
+ * To save us from swapping out pages which have just been swapped in and
+ * have not been modified since then, we keep in swap_cache[page>>PAGE_SHIFT]
+ * the swap entry which was last used to fill the page, or zero if the
+ * page does not currently correspond to a page in swap. PAGE_DIRTY makes
+ * this info useless.
+ */
+unsigned long *swap_cache;
+
+#ifdef SWAP_CACHE_INFO
+unsigned long swap_cache_add_total = 0;
+unsigned long swap_cache_add_success = 0;
+unsigned long swap_cache_del_total = 0;
+unsigned long swap_cache_del_success = 0;
+unsigned long swap_cache_find_total = 0;
+unsigned long swap_cache_find_success = 0;
+
+void show_swap_cache_info(void)
+{
+	printk("Swap cache: add %ld/%ld, delete %ld/%ld, find %ld/%ld\n",
+		swap_cache_add_total, swap_cache_add_success, 
+		swap_cache_del_total, swap_cache_del_success,
+		swap_cache_find_total, swap_cache_find_success);
+}
+#endif
+
+int add_to_swap_cache(unsigned long addr, unsigned long entry)
+{
+	struct swap_info_struct * p = &swap_info[SWP_TYPE(entry)];
+
+#ifdef SWAP_CACHE_INFO
+	swap_cache_add_total++;
+#endif
+	if ((p->flags & SWP_WRITEOK) == SWP_WRITEOK) {
+		entry = xchg(swap_cache + MAP_NR(addr), entry);
+		if (entry)  {
+			printk("swap_cache: replacing non-NULL entry\n");
+		}
+#ifdef SWAP_CACHE_INFO
+		swap_cache_add_success++;
+#endif
+		return 1;
+	}
+	return 0;
+}
+
+unsigned long init_swap_cache(unsigned long mem_start,
+	unsigned long mem_end)
+{
+	unsigned long swap_cache_size;
+
+	mem_start = (mem_start + 15) & ~15;
+	swap_cache = (unsigned long *) mem_start;
+	swap_cache_size = MAP_NR(mem_end);
+	memset(swap_cache, 0, swap_cache_size * sizeof (unsigned long));
+	return (unsigned long) (swap_cache + swap_cache_size);
+}
+
+void swap_duplicate(unsigned long entry)
+{
+	struct swap_info_struct * p;
+	unsigned long offset, type;
+
+	if (!entry)
+		return;
+	offset = SWP_OFFSET(entry);
+	type = SWP_TYPE(entry);
+	if (type & SHM_SWP_TYPE)
+		return;
+	if (type >= nr_swapfiles) {
+		printk("Trying to duplicate nonexistent swap-page\n");
+		return;
+	}
+	p = type + swap_info;
+	if (offset >= p->max) {
+		printk("swap_duplicate: weirdness\n");
+		return;
+	}
+	if (!p->swap_map[offset]) {
+		printk("swap_duplicate: trying to duplicate unused page\n");
+		return;
+	}
+	p->swap_map[offset]++;
+	return;
+}
+