1/*
2 * linux/kernel/power/swap.c
3 *
4 * This file provides functions for reading the suspend image from
5 * and writing it to a swap partition.
6 *
7 * Copyright (C) 1998,2001-2005 Pavel Machek <pavel@suse.cz>
8 * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
9 *
10 * This file is released under the GPLv2.
11 *
12 */
13
14#include <linux/module.h>
15#include <linux/file.h>
16#include <linux/utsname.h>
17#include <linux/version.h>
18#include <linux/delay.h>
19#include <linux/bitops.h>
20#include <linux/genhd.h>
21#include <linux/device.h>
22#include <linux/buffer_head.h>
23#include <linux/bio.h>
24#include <linux/blkdev.h>
25#include <linux/swap.h>
26#include <linux/swapops.h>
27#include <linux/pm.h>
28
29#include "power.h"
30
31extern char resume_file[];
32
33#define SWSUSP_SIG	"S1SUSPEND"
34
35struct swsusp_header {
36	char reserved[PAGE_SIZE - 20 - sizeof(sector_t)];
37	sector_t image;
38	char	orig_sig[10];
39	char	sig[10];
40} __attribute__((packed));
41
42static struct swsusp_header *swsusp_header;
43
44/*
45 * General things
46 */
47
48static unsigned short root_swap = 0xffff;
49static struct block_device *resume_bdev;
50
51/**
52 *	submit - submit BIO request.
53 *	@rw:	READ or WRITE.
54 *	@off	physical offset of page.
55 *	@page:	page we're reading or writing.
56 *	@bio_chain: list of pending biod (for async reading)
57 *
58 *	Straight from the textbook - allocate and initialize the bio.
59 *	If we're reading, make sure the page is marked as dirty.
60 *	Then submit it and, if @bio_chain == NULL, wait.
61 */
62static int submit(int rw, pgoff_t page_off, struct page *page,
63			struct bio **bio_chain)
64{
65	struct bio *bio;
66
67	bio = bio_alloc(__GFP_WAIT | __GFP_HIGH, 1);
68	if (!bio)
69		return -ENOMEM;
70	bio->bi_sector = page_off * (PAGE_SIZE >> 9);
71	bio->bi_bdev = resume_bdev;
72	bio->bi_end_io = end_swap_bio_read;
73
74	if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) {
75		printk("swsusp: ERROR: adding page to bio at %ld\n", page_off);
76		bio_put(bio);
77		return -EFAULT;
78	}
79
80	lock_page(page);
81	bio_get(bio);
82
83	if (bio_chain == NULL) {
84		submit_bio(rw | (1 << BIO_RW_SYNC), bio);
85		wait_on_page_locked(page);
86		if (rw == READ)
87			bio_set_pages_dirty(bio);
88		bio_put(bio);
89	} else {
90		if (rw == READ)
91			get_page(page);	/* These pages are freed later */
92		bio->bi_private = *bio_chain;
93		*bio_chain = bio;
94		submit_bio(rw | (1 << BIO_RW_SYNC), bio);
95	}
96	return 0;
97}
98
99static int bio_read_page(pgoff_t page_off, void *addr, struct bio **bio_chain)
100{
101	return submit(READ, page_off, virt_to_page(addr), bio_chain);
102}
103
104static int bio_write_page(pgoff_t page_off, void *addr, struct bio **bio_chain)
105{
106	return submit(WRITE, page_off, virt_to_page(addr), bio_chain);
107}
108
109static int wait_on_bio_chain(struct bio **bio_chain)
110{
111	struct bio *bio;
112	struct bio *next_bio;
113	int ret = 0;
114
115	if (bio_chain == NULL)
116		return 0;
117
118	bio = *bio_chain;
119	if (bio == NULL)
120		return 0;
121	while (bio) {
122		struct page *page;
123
124		next_bio = bio->bi_private;
125		page = bio->bi_io_vec[0].bv_page;
126		wait_on_page_locked(page);
127		if (!PageUptodate(page) || PageError(page))
128			ret = -EIO;
129		put_page(page);
130		bio_put(bio);
131		bio = next_bio;
132	}
133	*bio_chain = NULL;
134	return ret;
135}
136
137/*
138 * Saving part
139 */
140
141static int mark_swapfiles(sector_t start)
142{
143	int error;
144
145	bio_read_page(swsusp_resume_block, swsusp_header, NULL);
146	if (!memcmp("SWAP-SPACE",swsusp_header->sig, 10) ||
147	    !memcmp("SWAPSPACE2",swsusp_header->sig, 10)) {
148		memcpy(swsusp_header->orig_sig,swsusp_header->sig, 10);
149		memcpy(swsusp_header->sig,SWSUSP_SIG, 10);
150		swsusp_header->image = start;
151		error = bio_write_page(swsusp_resume_block,
152					swsusp_header, NULL);
153	} else {
154		printk(KERN_ERR "swsusp: Swap header not found!\n");
155		error = -ENODEV;
156	}
157	return error;
158}
159
160/**
161 *	swsusp_swap_check - check if the resume device is a swap device
162 *	and get its index (if so)
163 */
164
165static int swsusp_swap_check(void) /* This is called before saving image */
166{
167	int res;
168
169	res = swap_type_of(swsusp_resume_device, swsusp_resume_block,
170			&resume_bdev);
171	if (res < 0)
172		return res;
173
174	root_swap = res;
175	res = blkdev_get(resume_bdev, FMODE_WRITE, O_RDWR);
176	if (res)
177		return res;
178
179	res = set_blocksize(resume_bdev, PAGE_SIZE);
180	if (res < 0)
181		blkdev_put(resume_bdev);
182
183	return res;
184}
185
186/**
187 *	write_page - Write one page to given swap location.
188 *	@buf:		Address we're writing.
189 *	@offset:	Offset of the swap page we're writing to.
190 *	@bio_chain:	Link the next write BIO here
191 */
192
193static int write_page(void *buf, sector_t offset, struct bio **bio_chain)
194{
195	void *src;
196
197	if (!offset)
198		return -ENOSPC;
199
200	if (bio_chain) {
201		src = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
202		if (src) {
203			memcpy(src, buf, PAGE_SIZE);
204		} else {
205			WARN_ON_ONCE(1);
206			bio_chain = NULL;	/* Go synchronous */
207			src = buf;
208		}
209	} else {
210		src = buf;
211	}
212	return bio_write_page(offset, src, bio_chain);
213}
214
215/*
216 *	The swap map is a data structure used for keeping track of each page
217 *	written to a swap partition.  It consists of many swap_map_page
218 *	structures that contain each an array of MAP_PAGE_SIZE swap entries.
219 *	These structures are stored on the swap and linked together with the
220 *	help of the .next_swap member.
221 *
222 *	The swap map is created during suspend.  The swap map pages are
223 *	allocated and populated one at a time, so we only need one memory
224 *	page to set up the entire structure.
225 *
226 *	During resume we also only need to use one swap_map_page structure
227 *	at a time.
228 */
229
230#define MAP_PAGE_ENTRIES	(PAGE_SIZE / sizeof(sector_t) - 1)
231
232struct swap_map_page {
233	sector_t entries[MAP_PAGE_ENTRIES];
234	sector_t next_swap;
235};
236
237/**
238 *	The swap_map_handle structure is used for handling swap in
239 *	a file-alike way
240 */
241
242struct swap_map_handle {
243	struct swap_map_page *cur;
244	sector_t cur_swap;
245	unsigned int k;
246};
247
248static void release_swap_writer(struct swap_map_handle *handle)
249{
250	if (handle->cur)
251		free_page((unsigned long)handle->cur);
252	handle->cur = NULL;
253}
254
255static int get_swap_writer(struct swap_map_handle *handle)
256{
257	handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL);
258	if (!handle->cur)
259		return -ENOMEM;
260	handle->cur_swap = alloc_swapdev_block(root_swap);
261	if (!handle->cur_swap) {
262		release_swap_writer(handle);
263		return -ENOSPC;
264	}
265	handle->k = 0;
266	return 0;
267}
268
269static int swap_write_page(struct swap_map_handle *handle, void *buf,
270				struct bio **bio_chain)
271{
272	int error = 0;
273	sector_t offset;
274
275	if (!handle->cur)
276		return -EINVAL;
277	offset = alloc_swapdev_block(root_swap);
278	error = write_page(buf, offset, bio_chain);
279	if (error)
280		return error;
281	handle->cur->entries[handle->k++] = offset;
282	if (handle->k >= MAP_PAGE_ENTRIES) {
283		error = wait_on_bio_chain(bio_chain);
284		if (error)
285			goto out;
286		offset = alloc_swapdev_block(root_swap);
287		if (!offset)
288			return -ENOSPC;
289		handle->cur->next_swap = offset;
290		error = write_page(handle->cur, handle->cur_swap, NULL);
291		if (error)
292			goto out;
293		memset(handle->cur, 0, PAGE_SIZE);
294		handle->cur_swap = offset;
295		handle->k = 0;
296	}
297 out:
298	return error;
299}
300
301static int flush_swap_writer(struct swap_map_handle *handle)
302{
303	if (handle->cur && handle->cur_swap)
304		return write_page(handle->cur, handle->cur_swap, NULL);
305	else
306		return -EINVAL;
307}
308
309/**
310 *	save_image - save the suspend image data
311 */
312
313static int save_image(struct swap_map_handle *handle,
314                      struct snapshot_handle *snapshot,
315                      unsigned int nr_to_write)
316{
317	unsigned int m;
318	int ret;
319	int error = 0;
320	int nr_pages;
321	int err2;
322	struct bio *bio;
323	struct timeval start;
324	struct timeval stop;
325
326	printk("Saving image data pages (%u pages) ...     ", nr_to_write);
327	m = nr_to_write / 100;
328	if (!m)
329		m = 1;
330	nr_pages = 0;
331	bio = NULL;
332	do_gettimeofday(&start);
333	do {
334		ret = snapshot_read_next(snapshot, PAGE_SIZE);
335		if (ret > 0) {
336			error = swap_write_page(handle, data_of(*snapshot),
337						&bio);
338			if (error)
339				break;
340			if (!(nr_pages % m))
341				printk("\b\b\b\b%3d%%", nr_pages / m);
342			nr_pages++;
343		}
344	} while (ret > 0);
345	err2 = wait_on_bio_chain(&bio);
346	do_gettimeofday(&stop);
347	if (!error)
348		error = err2;
349	if (!error)
350		printk("\b\b\b\bdone\n");
351	swsusp_show_speed(&start, &stop, nr_to_write, "Wrote");
352	return error;
353}
354
355/**
356 *	enough_swap - Make sure we have enough swap to save the image.
357 *
358 *	Returns TRUE or FALSE after checking the total amount of swap
359 *	space avaiable from the resume partition.
360 */
361
362static int enough_swap(unsigned int nr_pages)
363{
364	unsigned int free_swap = count_swap_pages(root_swap, 1);
365
366	pr_debug("swsusp: free swap pages: %u\n", free_swap);
367	return free_swap > nr_pages + PAGES_FOR_IO;
368}
369
370/**
371 *	swsusp_write - Write entire image and metadata.
372 *
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.)
377 */
378
379int swsusp_write(void)
380{
381	struct swap_map_handle handle;
382	struct snapshot_handle snapshot;
383	struct swsusp_info *header;
384	int error;
385
386	error = swsusp_swap_check();
387	if (error) {
388		printk(KERN_ERR "swsusp: Cannot find swap device, try "
389				"swapon -a.\n");
390		return error;
391	}
392	memset(&snapshot, 0, sizeof(struct snapshot_handle));
393	error = snapshot_read_next(&snapshot, PAGE_SIZE);
394	if (error < PAGE_SIZE) {
395		if (error >= 0)
396			error = -EFAULT;
397
398		goto out;
399	}
400	header = (struct swsusp_info *)data_of(snapshot);
401	if (!enough_swap(header->pages)) {
402		printk(KERN_ERR "swsusp: Not enough free swap\n");
403		error = -ENOSPC;
404		goto out;
405	}
406	error = get_swap_writer(&handle);
407	if (!error) {
408		sector_t start = handle.cur_swap;
409
410		error = swap_write_page(&handle, header, NULL);
411		if (!error)
412			error = save_image(&handle, &snapshot,
413					header->pages - 1);
414
415		if (!error) {
416			flush_swap_writer(&handle);
417			printk("S");
418			error = mark_swapfiles(start);
419			printk("|\n");
420		}
421	}
422	if (error)
423		free_all_swap_pages(root_swap);
424
425	release_swap_writer(&handle);
426 out:
427	swsusp_close();
428	return error;
429}
430
431/**
432 *	The following functions allow us to read data using a swap map
433 *	in a file-alike way
434 */
435
436static void release_swap_reader(struct swap_map_handle *handle)
437{
438	if (handle->cur)
439		free_page((unsigned long)handle->cur);
440	handle->cur = NULL;
441}
442
443static int get_swap_reader(struct swap_map_handle *handle, sector_t start)
444{
445	int error;
446
447	if (!start)
448		return -EINVAL;
449
450	handle->cur = (struct swap_map_page *)get_zeroed_page(__GFP_WAIT | __GFP_HIGH);
451	if (!handle->cur)
452		return -ENOMEM;
453
454	error = bio_read_page(start, handle->cur, NULL);
455	if (error) {
456		release_swap_reader(handle);
457		return error;
458	}
459	handle->k = 0;
460	return 0;
461}
462
463static int swap_read_page(struct swap_map_handle *handle, void *buf,
464				struct bio **bio_chain)
465{
466	sector_t offset;
467	int error;
468
469	if (!handle->cur)
470		return -EINVAL;
471	offset = handle->cur->entries[handle->k];
472	if (!offset)
473		return -EFAULT;
474	error = bio_read_page(offset, buf, bio_chain);
475	if (error)
476		return error;
477	if (++handle->k >= MAP_PAGE_ENTRIES) {
478		error = wait_on_bio_chain(bio_chain);
479		handle->k = 0;
480		offset = handle->cur->next_swap;
481		if (!offset)
482			release_swap_reader(handle);
483		else if (!error)
484			error = bio_read_page(offset, handle->cur, NULL);
485	}
486	return error;
487}
488
489/**
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)
493 */
494
495static int load_image(struct swap_map_handle *handle,
496                      struct snapshot_handle *snapshot,
497                      unsigned int nr_to_read)
498{
499	unsigned int m;
500	int error = 0;
501	struct timeval start;
502	struct timeval stop;
503	struct bio *bio;
504	int err2;
505	unsigned nr_pages;
506
507	printk("Loading image data pages (%u pages) ...     ", nr_to_read);
508	m = nr_to_read / 100;
509	if (!m)
510		m = 1;
511	nr_pages = 0;
512	bio = NULL;
513	do_gettimeofday(&start);
514	for ( ; ; ) {
515		error = snapshot_write_next(snapshot, PAGE_SIZE);
516		if (error <= 0)
517			break;
518		error = swap_read_page(handle, data_of(*snapshot), &bio);
519		if (error)
520			break;
521		if (snapshot->sync_read)
522			error = wait_on_bio_chain(&bio);
523		if (error)
524			break;
525		if (!(nr_pages % m))
526			printk("\b\b\b\b%3d%%", nr_pages / m);
527		nr_pages++;
528	}
529	err2 = wait_on_bio_chain(&bio);
530	do_gettimeofday(&stop);
531	if (!error)
532		error = err2;
533	if (!error) {
534		printk("\b\b\b\bdone\n");
535		snapshot_write_finalize(snapshot);
536		if (!snapshot_image_loaded(snapshot))
537			error = -ENODATA;
538	}
539	swsusp_show_speed(&start, &stop, nr_to_read, "Read");
540	return error;
541}
542
543int swsusp_read(void)
544{
545	int error;
546	struct swap_map_handle handle;
547	struct snapshot_handle snapshot;
548	struct swsusp_info *header;
549
550	if (IS_ERR(resume_bdev)) {
551		pr_debug("swsusp: block device not initialised\n");
552		return PTR_ERR(resume_bdev);
553	}
554
555	memset(&snapshot, 0, sizeof(struct snapshot_handle));
556	error = snapshot_write_next(&snapshot, PAGE_SIZE);
557	if (error < PAGE_SIZE)
558		return error < 0 ? error : -EFAULT;
559	header = (struct swsusp_info *)data_of(snapshot);
560	error = get_swap_reader(&handle, swsusp_header->image);
561	if (!error)
562		error = swap_read_page(&handle, header, NULL);
563	if (!error)
564		error = load_image(&handle, &snapshot, header->pages - 1);
565	release_swap_reader(&handle);
566
567	blkdev_put(resume_bdev);
568
569	if (!error)
570		pr_debug("swsusp: Reading resume file was successful\n");
571	else
572		pr_debug("swsusp: Error %d resuming\n", error);
573	return error;
574}
575
576/**
577 *      swsusp_check - Check for swsusp signature in the resume device
578 */
579
580int swsusp_check(void)
581{
582	int error;
583
584	resume_bdev = open_by_devnum(swsusp_resume_device, FMODE_READ);
585	if (!IS_ERR(resume_bdev)) {
586		set_blocksize(resume_bdev, PAGE_SIZE);
587		memset(swsusp_header, 0, PAGE_SIZE);
588		error = bio_read_page(swsusp_resume_block,
589					swsusp_header, NULL);
590		if (error)
591			return error;
592
593		if (!memcmp(SWSUSP_SIG, swsusp_header->sig, 10)) {
594			memcpy(swsusp_header->sig, swsusp_header->orig_sig, 10);
595			/* Reset swap signature now */
596			error = bio_write_page(swsusp_resume_block,
597						swsusp_header, NULL);
598		} else {
599			return -EINVAL;
600		}
601		if (error)
602			blkdev_put(resume_bdev);
603		else
604			pr_debug("swsusp: Signature found, resuming\n");
605	} else {
606		error = PTR_ERR(resume_bdev);
607	}
608
609	if (error)
610		pr_debug("swsusp: Error %d check for resume file\n", error);
611
612	return error;
613}
614
615/**
616 *	swsusp_close - close swap device.
617 */
618
619void swsusp_close(void)
620{
621	if (IS_ERR(resume_bdev)) {
622		pr_debug("swsusp: block device not initialised\n");
623		return;
624	}
625
626	blkdev_put(resume_bdev);
627}
628
629static int swsusp_header_init(void)
630{
631	swsusp_header = (struct swsusp_header*) __get_free_page(GFP_KERNEL);
632	if (!swsusp_header)
633		panic("Could not allocate memory for swsusp_header\n");
634	return 0;
635}
636
637core_initcall(swsusp_header_init);
638