patch-1.3.57 linux/mm/page_io.c

• Lines: 109
• Date: Tue Jan 9 20:56:47 1996
• Orig file: v1.3.56/linux/mm/page_io.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.56/linux/mm/page_io.c linux/mm/page_io.c
@@ -0,0 +1,108 @@
+/*
+ *  linux/mm/page_io.c
+ *
+ *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
+ *
+ *  Swap reorganised 29.12.95, 
+ *  Asynchronous swapping added 30.12.95. 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/locks.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>
+
+static struct wait_queue * lock_queue = NULL;
+
+void rw_swap_page(int rw, unsigned long entry, char * buf)
+{
+	unsigned long type, offset;
+	struct swap_info_struct * p;
+
+	type = SWP_TYPE(entry);
+	if (type >= nr_swapfiles) {
+		printk("Internal error: bad swap-device\n");
+		return;
+	}
+	p = &swap_info[type];
+	offset = SWP_OFFSET(entry);
+	if (offset >= p->max) {
+		printk("rw_swap_page: weirdness\n");
+		return;
+	}
+	if (p->swap_map && !p->swap_map[offset]) {
+		printk("Hmm.. Trying to use unallocated swap (%08lx)\n", entry);
+		return;
+	}
+	if (!(p->flags & SWP_USED)) {
+		printk("Trying to swap to unused swap-device\n");
+		return;
+	}
+	while (set_bit(offset,p->swap_lockmap))
+		sleep_on(&lock_queue);
+	if (rw == READ)
+		kstat.pswpin++;
+	else
+		kstat.pswpout++;
+	if (p->swap_device) {
+		ll_rw_page(rw,p->swap_device,offset,buf);
+	} else if (p->swap_file) {
+		struct inode *swapf = p->swap_file;
+		unsigned int zones[PAGE_SIZE/512];
+		int i;
+		if (swapf->i_op->bmap == NULL
+			&& swapf->i_op->smap != NULL){
+			/*
+				With MsDOS, we use msdos_smap which return
+				a sector number (not a cluster or block number).
+				It is a patch to enable the UMSDOS project.
+				Other people are working on better solution.
+
+				It sounds like ll_rw_swap_file defined
+				it operation size (sector size) based on
+				PAGE_SIZE and the number of block to read.
+				So using bmap or smap should work even if
+				smap will require more blocks.
+			*/
+			int j;
+			unsigned int block = offset << 3;
+
+			for (i=0, j=0; j< PAGE_SIZE ; i++, j += 512){
+				if (!(zones[i] = swapf->i_op->smap(swapf,block++))) {
+					printk("rw_swap_page: bad swap file\n");
+					return;
+				}
+			}
+		}else{
+			int j;
+			unsigned int block = offset
+				<< (PAGE_SHIFT - swapf->i_sb->s_blocksize_bits);
+
+			for (i=0, j=0; j< PAGE_SIZE ; i++, j +=swapf->i_sb->s_blocksize)
+				if (!(zones[i] = bmap(swapf,block++))) {
+					printk("rw_swap_page: bad swap file\n");
+					return;
+				}
+		}
+		ll_rw_swap_file(rw,swapf->i_dev, zones, i,buf);
+	} else
+		printk("re_swap_page: no swap file or device\n");
+	if (offset && !clear_bit(offset,p->swap_lockmap))
+		printk("rw_swap_page: lock already cleared\n");
+	wake_up(&lock_queue);
+}
+