2 * linux/kernel/power/swap.c
4 * This file provides functions for reading the suspend image from
5 * and writing it to a swap partition.
7 * Copyright (C) 1998,2001-2005 Pavel Machek <pavel@suse.cz>
8 * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
10 * This file is released under the GPLv2.
14 #include <linux/module.h>
15 #include <linux/file.h>
16 #include <linux/delay.h>
17 #include <linux/bitops.h>
18 #include <linux/genhd.h>
19 #include <linux/device.h>
20 #include <linux/buffer_head.h>
21 #include <linux/bio.h>
22 #include <linux/blkdev.h>
23 #include <linux/swap.h>
24 #include <linux/swapops.h>
29 #define SWSUSP_SIG "S1SUSPEND"
31 struct swsusp_header {
32 char reserved[PAGE_SIZE - 20 - sizeof(sector_t) - sizeof(int)];
34 unsigned int flags; /* Flags to pass to the "boot" kernel */
37 } __attribute__((packed));
39 static struct swsusp_header *swsusp_header;
45 static unsigned short root_swap = 0xffff;
46 static struct block_device *resume_bdev;
49 * submit - submit BIO request.
51 * @off physical offset of page.
52 * @page: page we're reading or writing.
53 * @bio_chain: list of pending biod (for async reading)
55 * Straight from the textbook - allocate and initialize the bio.
56 * If we're reading, make sure the page is marked as dirty.
57 * Then submit it and, if @bio_chain == NULL, wait.
59 static int submit(int rw, pgoff_t page_off, struct page *page,
60 struct bio **bio_chain)
62 const int bio_rw = rw | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG);
65 bio = bio_alloc(__GFP_WAIT | __GFP_HIGH, 1);
66 bio->bi_sector = page_off * (PAGE_SIZE >> 9);
67 bio->bi_bdev = resume_bdev;
68 bio->bi_end_io = end_swap_bio_read;
70 if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) {
71 printk(KERN_ERR "PM: Adding page to bio failed at %ld\n",
80 if (bio_chain == NULL) {
81 submit_bio(bio_rw, bio);
82 wait_on_page_locked(page);
84 bio_set_pages_dirty(bio);
88 get_page(page); /* These pages are freed later */
89 bio->bi_private = *bio_chain;
91 submit_bio(bio_rw, bio);
96 static int bio_read_page(pgoff_t page_off, void *addr, struct bio **bio_chain)
98 return submit(READ, page_off, virt_to_page(addr), bio_chain);
101 static int bio_write_page(pgoff_t page_off, void *addr, struct bio **bio_chain)
103 return submit(WRITE, page_off, virt_to_page(addr), bio_chain);
106 static int wait_on_bio_chain(struct bio **bio_chain)
109 struct bio *next_bio;
112 if (bio_chain == NULL)
121 next_bio = bio->bi_private;
122 page = bio->bi_io_vec[0].bv_page;
123 wait_on_page_locked(page);
124 if (!PageUptodate(page) || PageError(page))
138 static int mark_swapfiles(sector_t start, unsigned int flags)
142 bio_read_page(swsusp_resume_block, swsusp_header, NULL);
143 if (!memcmp("SWAP-SPACE",swsusp_header->sig, 10) ||
144 !memcmp("SWAPSPACE2",swsusp_header->sig, 10)) {
145 memcpy(swsusp_header->orig_sig,swsusp_header->sig, 10);
146 memcpy(swsusp_header->sig,SWSUSP_SIG, 10);
147 swsusp_header->image = start;
148 swsusp_header->flags = flags;
149 error = bio_write_page(swsusp_resume_block,
150 swsusp_header, NULL);
152 printk(KERN_ERR "PM: Swap header not found!\n");
159 * swsusp_swap_check - check if the resume device is a swap device
160 * and get its index (if so)
163 static int swsusp_swap_check(void) /* This is called before saving image */
167 res = swap_type_of(swsusp_resume_device, swsusp_resume_block,
173 res = blkdev_get(resume_bdev, FMODE_WRITE);
177 res = set_blocksize(resume_bdev, PAGE_SIZE);
179 blkdev_put(resume_bdev, FMODE_WRITE);
185 * write_page - Write one page to given swap location.
186 * @buf: Address we're writing.
187 * @offset: Offset of the swap page we're writing to.
188 * @bio_chain: Link the next write BIO here
191 static int write_page(void *buf, sector_t offset, struct bio **bio_chain)
199 src = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
201 memcpy(src, buf, PAGE_SIZE);
204 bio_chain = NULL; /* Go synchronous */
210 return bio_write_page(offset, src, bio_chain);
214 * The swap map is a data structure used for keeping track of each page
215 * written to a swap partition. It consists of many swap_map_page
216 * structures that contain each an array of MAP_PAGE_SIZE swap entries.
217 * These structures are stored on the swap and linked together with the
218 * help of the .next_swap member.
220 * The swap map is created during suspend. The swap map pages are
221 * allocated and populated one at a time, so we only need one memory
222 * page to set up the entire structure.
224 * During resume we also only need to use one swap_map_page structure
228 #define MAP_PAGE_ENTRIES (PAGE_SIZE / sizeof(sector_t) - 1)
230 struct swap_map_page {
231 sector_t entries[MAP_PAGE_ENTRIES];
236 * The swap_map_handle structure is used for handling swap in
240 struct swap_map_handle {
241 struct swap_map_page *cur;
246 static void release_swap_writer(struct swap_map_handle *handle)
249 free_page((unsigned long)handle->cur);
253 static int get_swap_writer(struct swap_map_handle *handle)
255 handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL);
258 handle->cur_swap = alloc_swapdev_block(root_swap);
259 if (!handle->cur_swap) {
260 release_swap_writer(handle);
267 static int swap_write_page(struct swap_map_handle *handle, void *buf,
268 struct bio **bio_chain)
275 offset = alloc_swapdev_block(root_swap);
276 error = write_page(buf, offset, bio_chain);
279 handle->cur->entries[handle->k++] = offset;
280 if (handle->k >= MAP_PAGE_ENTRIES) {
281 error = wait_on_bio_chain(bio_chain);
284 offset = alloc_swapdev_block(root_swap);
287 handle->cur->next_swap = offset;
288 error = write_page(handle->cur, handle->cur_swap, NULL);
291 memset(handle->cur, 0, PAGE_SIZE);
292 handle->cur_swap = offset;
299 static int flush_swap_writer(struct swap_map_handle *handle)
301 if (handle->cur && handle->cur_swap)
302 return write_page(handle->cur, handle->cur_swap, NULL);
308 * save_image - save the suspend image data
311 static int save_image(struct swap_map_handle *handle,
312 struct snapshot_handle *snapshot,
313 unsigned int nr_to_write)
320 struct timeval start;
323 printk(KERN_INFO "PM: Saving image data pages (%u pages) ... ",
325 m = nr_to_write / 100;
330 do_gettimeofday(&start);
332 ret = snapshot_read_next(snapshot, PAGE_SIZE);
335 ret = swap_write_page(handle, data_of(*snapshot), &bio);
339 printk("\b\b\b\b%3d%%", nr_pages / m);
342 err2 = wait_on_bio_chain(&bio);
343 do_gettimeofday(&stop);
347 printk("\b\b\b\bdone\n");
350 swsusp_show_speed(&start, &stop, nr_to_write, "Wrote");
355 * enough_swap - Make sure we have enough swap to save the image.
357 * Returns TRUE or FALSE after checking the total amount of swap
358 * space avaiable from the resume partition.
361 static int enough_swap(unsigned int nr_pages)
363 unsigned int free_swap = count_swap_pages(root_swap, 1);
365 pr_debug("PM: Free swap pages: %u\n", free_swap);
366 return free_swap > nr_pages + PAGES_FOR_IO;
370 * swsusp_write - Write entire image and metadata.
371 * @flags: flags to pass to the "boot" kernel in the image header
373 * It is important _NOT_ to umount filesystems at this point. We want
374 * them synced (in case something goes wrong) but we DO not want to mark
375 * filesystem clean: it is not. (And it does not matter, if we resume
376 * correctly, we'll mark system clean, anyway.)
379 int swsusp_write(unsigned int flags)
381 struct swap_map_handle handle;
382 struct snapshot_handle snapshot;
383 struct swsusp_info *header;
386 error = swsusp_swap_check();
388 printk(KERN_ERR "PM: Cannot find swap device, try "
392 memset(&snapshot, 0, sizeof(struct snapshot_handle));
393 error = snapshot_read_next(&snapshot, PAGE_SIZE);
394 if (error < PAGE_SIZE) {
400 header = (struct swsusp_info *)data_of(snapshot);
401 if (!enough_swap(header->pages)) {
402 printk(KERN_ERR "PM: Not enough free swap\n");
406 error = get_swap_writer(&handle);
408 sector_t start = handle.cur_swap;
410 error = swap_write_page(&handle, header, NULL);
412 error = save_image(&handle, &snapshot,
416 flush_swap_writer(&handle);
417 printk(KERN_INFO "PM: S");
418 error = mark_swapfiles(start, flags);
423 free_all_swap_pages(root_swap);
425 release_swap_writer(&handle);
427 swsusp_close(FMODE_WRITE);
432 * The following functions allow us to read data using a swap map
433 * in a file-alike way
436 static void release_swap_reader(struct swap_map_handle *handle)
439 free_page((unsigned long)handle->cur);
443 static int get_swap_reader(struct swap_map_handle *handle, sector_t start)
450 handle->cur = (struct swap_map_page *)get_zeroed_page(__GFP_WAIT | __GFP_HIGH);
454 error = bio_read_page(start, handle->cur, NULL);
456 release_swap_reader(handle);
463 static int swap_read_page(struct swap_map_handle *handle, void *buf,
464 struct bio **bio_chain)
471 offset = handle->cur->entries[handle->k];
474 error = bio_read_page(offset, buf, bio_chain);
477 if (++handle->k >= MAP_PAGE_ENTRIES) {
478 error = wait_on_bio_chain(bio_chain);
480 offset = handle->cur->next_swap;
482 release_swap_reader(handle);
484 error = bio_read_page(offset, handle->cur, NULL);
490 * load_image - load the image using the swap map handle
491 * @handle and the snapshot handle @snapshot
492 * (assume there are @nr_pages pages to load)
495 static int load_image(struct swap_map_handle *handle,
496 struct snapshot_handle *snapshot,
497 unsigned int nr_to_read)
501 struct timeval start;
507 printk(KERN_INFO "PM: Loading image data pages (%u pages) ... ",
509 m = nr_to_read / 100;
514 do_gettimeofday(&start);
516 error = snapshot_write_next(snapshot, PAGE_SIZE);
519 error = swap_read_page(handle, data_of(*snapshot), &bio);
522 if (snapshot->sync_read)
523 error = wait_on_bio_chain(&bio);
527 printk("\b\b\b\b%3d%%", nr_pages / m);
530 err2 = wait_on_bio_chain(&bio);
531 do_gettimeofday(&stop);
535 printk("\b\b\b\bdone\n");
536 snapshot_write_finalize(snapshot);
537 if (!snapshot_image_loaded(snapshot))
541 swsusp_show_speed(&start, &stop, nr_to_read, "Read");
546 * swsusp_read - read the hibernation image.
547 * @flags_p: flags passed by the "frozen" kernel in the image header should
548 * be written into this memeory location
551 int swsusp_read(unsigned int *flags_p)
554 struct swap_map_handle handle;
555 struct snapshot_handle snapshot;
556 struct swsusp_info *header;
558 *flags_p = swsusp_header->flags;
559 if (IS_ERR(resume_bdev)) {
560 pr_debug("PM: Image device not initialised\n");
561 return PTR_ERR(resume_bdev);
564 memset(&snapshot, 0, sizeof(struct snapshot_handle));
565 error = snapshot_write_next(&snapshot, PAGE_SIZE);
566 if (error < PAGE_SIZE)
567 return error < 0 ? error : -EFAULT;
568 header = (struct swsusp_info *)data_of(snapshot);
569 error = get_swap_reader(&handle, swsusp_header->image);
571 error = swap_read_page(&handle, header, NULL);
573 error = load_image(&handle, &snapshot, header->pages - 1);
574 release_swap_reader(&handle);
577 pr_debug("PM: Image successfully loaded\n");
579 pr_debug("PM: Error %d resuming\n", error);
584 * swsusp_check - Check for swsusp signature in the resume device
587 int swsusp_check(void)
591 resume_bdev = open_by_devnum(swsusp_resume_device, FMODE_READ);
592 if (!IS_ERR(resume_bdev)) {
593 set_blocksize(resume_bdev, PAGE_SIZE);
594 memset(swsusp_header, 0, PAGE_SIZE);
595 error = bio_read_page(swsusp_resume_block,
596 swsusp_header, NULL);
600 if (!memcmp(SWSUSP_SIG, swsusp_header->sig, 10)) {
601 memcpy(swsusp_header->sig, swsusp_header->orig_sig, 10);
602 /* Reset swap signature now */
603 error = bio_write_page(swsusp_resume_block,
604 swsusp_header, NULL);
611 blkdev_put(resume_bdev, FMODE_READ);
613 pr_debug("PM: Signature found, resuming\n");
615 error = PTR_ERR(resume_bdev);
619 pr_debug("PM: Error %d checking image file\n", error);
625 * swsusp_close - close swap device.
628 void swsusp_close(fmode_t mode)
630 if (IS_ERR(resume_bdev)) {
631 pr_debug("PM: Image device not initialised\n");
635 blkdev_put(resume_bdev, mode);
638 static int swsusp_header_init(void)
640 swsusp_header = (struct swsusp_header*) __get_free_page(GFP_KERNEL);
642 panic("Could not allocate memory for swsusp_header\n");
646 core_initcall(swsusp_header_init);