![KAMEZAWA Hiroyuki](/assets/img/avatar_default.png)
When taking a memory snapshot in hibernate_snapshot(), all (directly called) memory allocations use GFP_ATOMIC. Hence swap misusage during hibernation never occurs. But from a pessimistic point of view, there is no guarantee that no page allcation has __GFP_WAIT. It is better to have a global indication "we enter hibernation, don't use swap!". This patch tries to freeze new-swap-allocation during hibernation. (All user processes are frozenm so swapin is not a concern). This way, no updates will happen to swap_map[] between hibernate_snapshot() and save_image(). Swap is thawed when swsusp_free() is called. We can be assured that swap corruption will not occur. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Hugh Dickins <hughd@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Ondrej Zary <linux@rainbow-software.org> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
690 lines
16 KiB
C
690 lines
16 KiB
C
/*
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* linux/kernel/power/swap.c
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*
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* This file provides functions for reading the suspend image from
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* and writing it to a swap partition.
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*
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* Copyright (C) 1998,2001-2005 Pavel Machek <pavel@ucw.cz>
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* Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
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*
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* This file is released under the GPLv2.
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*
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*/
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#include <linux/module.h>
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#include <linux/file.h>
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#include <linux/delay.h>
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#include <linux/bitops.h>
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#include <linux/genhd.h>
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#include <linux/device.h>
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#include <linux/buffer_head.h>
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#include <linux/bio.h>
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#include <linux/blkdev.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/pm.h>
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#include <linux/slab.h>
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#include "power.h"
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#define SWSUSP_SIG "S1SUSPEND"
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/*
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* The swap map is a data structure used for keeping track of each page
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* written to a swap partition. It consists of many swap_map_page
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* structures that contain each an array of MAP_PAGE_ENTRIES swap entries.
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* These structures are stored on the swap and linked together with the
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* help of the .next_swap member.
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*
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* The swap map is created during suspend. The swap map pages are
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* allocated and populated one at a time, so we only need one memory
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* page to set up the entire structure.
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*
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* During resume we also only need to use one swap_map_page structure
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* at a time.
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*/
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#define MAP_PAGE_ENTRIES (PAGE_SIZE / sizeof(sector_t) - 1)
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struct swap_map_page {
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sector_t entries[MAP_PAGE_ENTRIES];
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sector_t next_swap;
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};
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/**
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* The swap_map_handle structure is used for handling swap in
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* a file-alike way
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*/
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struct swap_map_handle {
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struct swap_map_page *cur;
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sector_t cur_swap;
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sector_t first_sector;
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unsigned int k;
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};
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struct swsusp_header {
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char reserved[PAGE_SIZE - 20 - sizeof(sector_t) - sizeof(int)];
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sector_t image;
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unsigned int flags; /* Flags to pass to the "boot" kernel */
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char orig_sig[10];
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char sig[10];
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} __attribute__((packed));
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static struct swsusp_header *swsusp_header;
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/**
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* The following functions are used for tracing the allocated
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* swap pages, so that they can be freed in case of an error.
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*/
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struct swsusp_extent {
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struct rb_node node;
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unsigned long start;
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unsigned long end;
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};
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static struct rb_root swsusp_extents = RB_ROOT;
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static int swsusp_extents_insert(unsigned long swap_offset)
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{
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struct rb_node **new = &(swsusp_extents.rb_node);
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struct rb_node *parent = NULL;
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struct swsusp_extent *ext;
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/* Figure out where to put the new node */
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while (*new) {
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ext = container_of(*new, struct swsusp_extent, node);
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parent = *new;
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if (swap_offset < ext->start) {
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/* Try to merge */
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if (swap_offset == ext->start - 1) {
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ext->start--;
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return 0;
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}
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new = &((*new)->rb_left);
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} else if (swap_offset > ext->end) {
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/* Try to merge */
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if (swap_offset == ext->end + 1) {
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ext->end++;
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return 0;
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}
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new = &((*new)->rb_right);
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} else {
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/* It already is in the tree */
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return -EINVAL;
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}
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}
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/* Add the new node and rebalance the tree. */
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ext = kzalloc(sizeof(struct swsusp_extent), GFP_KERNEL);
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if (!ext)
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return -ENOMEM;
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ext->start = swap_offset;
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ext->end = swap_offset;
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rb_link_node(&ext->node, parent, new);
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rb_insert_color(&ext->node, &swsusp_extents);
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return 0;
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}
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/**
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* alloc_swapdev_block - allocate a swap page and register that it has
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* been allocated, so that it can be freed in case of an error.
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*/
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sector_t alloc_swapdev_block(int swap)
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{
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unsigned long offset;
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offset = swp_offset(get_swap_for_hibernation(swap));
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if (offset) {
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if (swsusp_extents_insert(offset))
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swap_free_for_hibernation(swp_entry(swap, offset));
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else
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return swapdev_block(swap, offset);
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}
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return 0;
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}
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/**
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* free_all_swap_pages - free swap pages allocated for saving image data.
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* It also frees the extents used to register which swap entries had been
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* allocated.
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*/
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void free_all_swap_pages(int swap)
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{
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struct rb_node *node;
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while ((node = swsusp_extents.rb_node)) {
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struct swsusp_extent *ext;
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unsigned long offset;
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ext = container_of(node, struct swsusp_extent, node);
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rb_erase(node, &swsusp_extents);
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for (offset = ext->start; offset <= ext->end; offset++)
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swap_free_for_hibernation(swp_entry(swap, offset));
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kfree(ext);
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}
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}
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int swsusp_swap_in_use(void)
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{
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return (swsusp_extents.rb_node != NULL);
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}
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/*
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* General things
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*/
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static unsigned short root_swap = 0xffff;
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struct block_device *hib_resume_bdev;
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/*
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* Saving part
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*/
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static int mark_swapfiles(struct swap_map_handle *handle, unsigned int flags)
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{
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int error;
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hib_bio_read_page(swsusp_resume_block, swsusp_header, NULL);
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if (!memcmp("SWAP-SPACE",swsusp_header->sig, 10) ||
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!memcmp("SWAPSPACE2",swsusp_header->sig, 10)) {
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memcpy(swsusp_header->orig_sig,swsusp_header->sig, 10);
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memcpy(swsusp_header->sig,SWSUSP_SIG, 10);
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swsusp_header->image = handle->first_sector;
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swsusp_header->flags = flags;
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error = hib_bio_write_page(swsusp_resume_block,
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swsusp_header, NULL);
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} else {
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printk(KERN_ERR "PM: Swap header not found!\n");
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error = -ENODEV;
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}
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return error;
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}
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/**
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* swsusp_swap_check - check if the resume device is a swap device
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* and get its index (if so)
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*
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* This is called before saving image
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*/
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static int swsusp_swap_check(void)
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{
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int res;
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res = swap_type_of(swsusp_resume_device, swsusp_resume_block,
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&hib_resume_bdev);
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if (res < 0)
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return res;
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root_swap = res;
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res = blkdev_get(hib_resume_bdev, FMODE_WRITE);
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if (res)
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return res;
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res = set_blocksize(hib_resume_bdev, PAGE_SIZE);
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if (res < 0)
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blkdev_put(hib_resume_bdev, FMODE_WRITE);
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return res;
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}
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/**
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* write_page - Write one page to given swap location.
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* @buf: Address we're writing.
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* @offset: Offset of the swap page we're writing to.
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* @bio_chain: Link the next write BIO here
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*/
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static int write_page(void *buf, sector_t offset, struct bio **bio_chain)
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{
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void *src;
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if (!offset)
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return -ENOSPC;
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if (bio_chain) {
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src = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
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if (src) {
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memcpy(src, buf, PAGE_SIZE);
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} else {
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WARN_ON_ONCE(1);
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bio_chain = NULL; /* Go synchronous */
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src = buf;
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}
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} else {
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src = buf;
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}
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return hib_bio_write_page(offset, src, bio_chain);
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}
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static void release_swap_writer(struct swap_map_handle *handle)
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{
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if (handle->cur)
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free_page((unsigned long)handle->cur);
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handle->cur = NULL;
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}
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static int get_swap_writer(struct swap_map_handle *handle)
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{
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int ret;
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ret = swsusp_swap_check();
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if (ret) {
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if (ret != -ENOSPC)
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printk(KERN_ERR "PM: Cannot find swap device, try "
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"swapon -a.\n");
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return ret;
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}
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handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL);
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if (!handle->cur) {
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ret = -ENOMEM;
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goto err_close;
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}
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handle->cur_swap = alloc_swapdev_block(root_swap);
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if (!handle->cur_swap) {
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ret = -ENOSPC;
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goto err_rel;
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}
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handle->k = 0;
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handle->first_sector = handle->cur_swap;
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return 0;
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err_rel:
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release_swap_writer(handle);
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err_close:
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swsusp_close(FMODE_WRITE);
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return ret;
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}
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static int swap_write_page(struct swap_map_handle *handle, void *buf,
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struct bio **bio_chain)
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{
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int error = 0;
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sector_t offset;
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if (!handle->cur)
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return -EINVAL;
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offset = alloc_swapdev_block(root_swap);
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error = write_page(buf, offset, bio_chain);
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if (error)
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return error;
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handle->cur->entries[handle->k++] = offset;
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if (handle->k >= MAP_PAGE_ENTRIES) {
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error = hib_wait_on_bio_chain(bio_chain);
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if (error)
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goto out;
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offset = alloc_swapdev_block(root_swap);
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if (!offset)
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return -ENOSPC;
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handle->cur->next_swap = offset;
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error = write_page(handle->cur, handle->cur_swap, NULL);
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if (error)
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goto out;
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memset(handle->cur, 0, PAGE_SIZE);
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handle->cur_swap = offset;
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handle->k = 0;
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}
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out:
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return error;
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}
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static int flush_swap_writer(struct swap_map_handle *handle)
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{
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if (handle->cur && handle->cur_swap)
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return write_page(handle->cur, handle->cur_swap, NULL);
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else
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return -EINVAL;
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}
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static int swap_writer_finish(struct swap_map_handle *handle,
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unsigned int flags, int error)
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{
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if (!error) {
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flush_swap_writer(handle);
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printk(KERN_INFO "PM: S");
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error = mark_swapfiles(handle, flags);
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printk("|\n");
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}
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if (error)
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free_all_swap_pages(root_swap);
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release_swap_writer(handle);
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swsusp_close(FMODE_WRITE);
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return error;
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}
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/**
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* save_image - save the suspend image data
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*/
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static int save_image(struct swap_map_handle *handle,
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struct snapshot_handle *snapshot,
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unsigned int nr_to_write)
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{
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unsigned int m;
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int ret;
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int nr_pages;
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int err2;
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struct bio *bio;
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struct timeval start;
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struct timeval stop;
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printk(KERN_INFO "PM: Saving image data pages (%u pages) ... ",
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nr_to_write);
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m = nr_to_write / 100;
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if (!m)
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m = 1;
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nr_pages = 0;
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bio = NULL;
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do_gettimeofday(&start);
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while (1) {
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ret = snapshot_read_next(snapshot);
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if (ret <= 0)
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break;
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ret = swap_write_page(handle, data_of(*snapshot), &bio);
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if (ret)
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break;
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if (!(nr_pages % m))
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printk(KERN_CONT "\b\b\b\b%3d%%", nr_pages / m);
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nr_pages++;
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}
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err2 = hib_wait_on_bio_chain(&bio);
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do_gettimeofday(&stop);
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if (!ret)
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ret = err2;
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if (!ret)
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printk(KERN_CONT "\b\b\b\bdone\n");
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else
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printk(KERN_CONT "\n");
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swsusp_show_speed(&start, &stop, nr_to_write, "Wrote");
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return ret;
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}
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/**
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* enough_swap - Make sure we have enough swap to save the image.
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*
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* Returns TRUE or FALSE after checking the total amount of swap
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* space avaiable from the resume partition.
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*/
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static int enough_swap(unsigned int nr_pages)
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{
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unsigned int free_swap = count_swap_pages(root_swap, 1);
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pr_debug("PM: Free swap pages: %u\n", free_swap);
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return free_swap > nr_pages + PAGES_FOR_IO;
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}
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/**
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* swsusp_write - Write entire image and metadata.
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* @flags: flags to pass to the "boot" kernel in the image header
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*
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* It is important _NOT_ to umount filesystems at this point. We want
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* them synced (in case something goes wrong) but we DO not want to mark
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* filesystem clean: it is not. (And it does not matter, if we resume
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* correctly, we'll mark system clean, anyway.)
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*/
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int swsusp_write(unsigned int flags)
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{
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struct swap_map_handle handle;
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struct snapshot_handle snapshot;
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struct swsusp_info *header;
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unsigned long pages;
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int error;
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pages = snapshot_get_image_size();
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error = get_swap_writer(&handle);
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if (error) {
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printk(KERN_ERR "PM: Cannot get swap writer\n");
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return error;
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}
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if (!enough_swap(pages)) {
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printk(KERN_ERR "PM: Not enough free swap\n");
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error = -ENOSPC;
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goto out_finish;
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}
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memset(&snapshot, 0, sizeof(struct snapshot_handle));
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error = snapshot_read_next(&snapshot);
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if (error < PAGE_SIZE) {
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if (error >= 0)
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error = -EFAULT;
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goto out_finish;
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}
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header = (struct swsusp_info *)data_of(snapshot);
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error = swap_write_page(&handle, header, NULL);
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if (!error)
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error = save_image(&handle, &snapshot, pages - 1);
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out_finish:
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error = swap_writer_finish(&handle, flags, error);
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return error;
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}
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/**
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* The following functions allow us to read data using a swap map
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* in a file-alike way
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*/
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static void release_swap_reader(struct swap_map_handle *handle)
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{
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if (handle->cur)
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free_page((unsigned long)handle->cur);
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handle->cur = NULL;
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}
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static int get_swap_reader(struct swap_map_handle *handle,
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unsigned int *flags_p)
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{
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int error;
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*flags_p = swsusp_header->flags;
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if (!swsusp_header->image) /* how can this happen? */
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return -EINVAL;
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handle->cur = (struct swap_map_page *)get_zeroed_page(__GFP_WAIT | __GFP_HIGH);
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if (!handle->cur)
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return -ENOMEM;
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error = hib_bio_read_page(swsusp_header->image, handle->cur, NULL);
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if (error) {
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release_swap_reader(handle);
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return error;
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}
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handle->k = 0;
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return 0;
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}
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static int swap_read_page(struct swap_map_handle *handle, void *buf,
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struct bio **bio_chain)
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{
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sector_t offset;
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int error;
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if (!handle->cur)
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return -EINVAL;
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offset = handle->cur->entries[handle->k];
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if (!offset)
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return -EFAULT;
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error = hib_bio_read_page(offset, buf, bio_chain);
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if (error)
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return error;
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if (++handle->k >= MAP_PAGE_ENTRIES) {
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error = hib_wait_on_bio_chain(bio_chain);
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handle->k = 0;
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offset = handle->cur->next_swap;
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if (!offset)
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release_swap_reader(handle);
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else if (!error)
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error = hib_bio_read_page(offset, handle->cur, NULL);
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}
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return error;
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}
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static int swap_reader_finish(struct swap_map_handle *handle)
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{
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release_swap_reader(handle);
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return 0;
|
|
}
|
|
|
|
/**
|
|
* load_image - load the image using the swap map handle
|
|
* @handle and the snapshot handle @snapshot
|
|
* (assume there are @nr_pages pages to load)
|
|
*/
|
|
|
|
static int load_image(struct swap_map_handle *handle,
|
|
struct snapshot_handle *snapshot,
|
|
unsigned int nr_to_read)
|
|
{
|
|
unsigned int m;
|
|
int error = 0;
|
|
struct timeval start;
|
|
struct timeval stop;
|
|
struct bio *bio;
|
|
int err2;
|
|
unsigned nr_pages;
|
|
|
|
printk(KERN_INFO "PM: Loading image data pages (%u pages) ... ",
|
|
nr_to_read);
|
|
m = nr_to_read / 100;
|
|
if (!m)
|
|
m = 1;
|
|
nr_pages = 0;
|
|
bio = NULL;
|
|
do_gettimeofday(&start);
|
|
for ( ; ; ) {
|
|
error = snapshot_write_next(snapshot);
|
|
if (error <= 0)
|
|
break;
|
|
error = swap_read_page(handle, data_of(*snapshot), &bio);
|
|
if (error)
|
|
break;
|
|
if (snapshot->sync_read)
|
|
error = hib_wait_on_bio_chain(&bio);
|
|
if (error)
|
|
break;
|
|
if (!(nr_pages % m))
|
|
printk("\b\b\b\b%3d%%", nr_pages / m);
|
|
nr_pages++;
|
|
}
|
|
err2 = hib_wait_on_bio_chain(&bio);
|
|
do_gettimeofday(&stop);
|
|
if (!error)
|
|
error = err2;
|
|
if (!error) {
|
|
printk("\b\b\b\bdone\n");
|
|
snapshot_write_finalize(snapshot);
|
|
if (!snapshot_image_loaded(snapshot))
|
|
error = -ENODATA;
|
|
} else
|
|
printk("\n");
|
|
swsusp_show_speed(&start, &stop, nr_to_read, "Read");
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* swsusp_read - read the hibernation image.
|
|
* @flags_p: flags passed by the "frozen" kernel in the image header should
|
|
* be written into this memeory location
|
|
*/
|
|
|
|
int swsusp_read(unsigned int *flags_p)
|
|
{
|
|
int error;
|
|
struct swap_map_handle handle;
|
|
struct snapshot_handle snapshot;
|
|
struct swsusp_info *header;
|
|
|
|
memset(&snapshot, 0, sizeof(struct snapshot_handle));
|
|
error = snapshot_write_next(&snapshot);
|
|
if (error < PAGE_SIZE)
|
|
return error < 0 ? error : -EFAULT;
|
|
header = (struct swsusp_info *)data_of(snapshot);
|
|
error = get_swap_reader(&handle, flags_p);
|
|
if (error)
|
|
goto end;
|
|
if (!error)
|
|
error = swap_read_page(&handle, header, NULL);
|
|
if (!error)
|
|
error = load_image(&handle, &snapshot, header->pages - 1);
|
|
swap_reader_finish(&handle);
|
|
end:
|
|
if (!error)
|
|
pr_debug("PM: Image successfully loaded\n");
|
|
else
|
|
pr_debug("PM: Error %d resuming\n", error);
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* swsusp_check - Check for swsusp signature in the resume device
|
|
*/
|
|
|
|
int swsusp_check(void)
|
|
{
|
|
int error;
|
|
|
|
hib_resume_bdev = open_by_devnum(swsusp_resume_device, FMODE_READ);
|
|
if (!IS_ERR(hib_resume_bdev)) {
|
|
set_blocksize(hib_resume_bdev, PAGE_SIZE);
|
|
memset(swsusp_header, 0, PAGE_SIZE);
|
|
error = hib_bio_read_page(swsusp_resume_block,
|
|
swsusp_header, NULL);
|
|
if (error)
|
|
goto put;
|
|
|
|
if (!memcmp(SWSUSP_SIG, swsusp_header->sig, 10)) {
|
|
memcpy(swsusp_header->sig, swsusp_header->orig_sig, 10);
|
|
/* Reset swap signature now */
|
|
error = hib_bio_write_page(swsusp_resume_block,
|
|
swsusp_header, NULL);
|
|
} else {
|
|
error = -EINVAL;
|
|
}
|
|
|
|
put:
|
|
if (error)
|
|
blkdev_put(hib_resume_bdev, FMODE_READ);
|
|
else
|
|
pr_debug("PM: Signature found, resuming\n");
|
|
} else {
|
|
error = PTR_ERR(hib_resume_bdev);
|
|
}
|
|
|
|
if (error)
|
|
pr_debug("PM: Error %d checking image file\n", error);
|
|
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* swsusp_close - close swap device.
|
|
*/
|
|
|
|
void swsusp_close(fmode_t mode)
|
|
{
|
|
if (IS_ERR(hib_resume_bdev)) {
|
|
pr_debug("PM: Image device not initialised\n");
|
|
return;
|
|
}
|
|
|
|
blkdev_put(hib_resume_bdev, mode);
|
|
}
|
|
|
|
static int swsusp_header_init(void)
|
|
{
|
|
swsusp_header = (struct swsusp_header*) __get_free_page(GFP_KERNEL);
|
|
if (!swsusp_header)
|
|
panic("Could not allocate memory for swsusp_header\n");
|
|
return 0;
|
|
}
|
|
|
|
core_initcall(swsusp_header_init);
|