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authorRafael J. Wysocki <rjw@sisk.pl>2006-03-23 06:00:00 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-23 10:38:07 -0500
commit61159a314bca6408320c3173c1282c64f5cdaa76 (patch)
tree8e1b7627443da0fd52b2fac66366dde9f7871f1e /kernel/power/swap.c
parentf577eb30afdc68233f25d4d82b04102129262365 (diff)
[PATCH] swsusp: separate swap-writing/reading code
Move the swap-writing/reading code of swsusp to a separate file. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/power/swap.c')
-rw-r--r--kernel/power/swap.c544
1 files changed, 544 insertions, 0 deletions
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
new file mode 100644
index 000000000000..9177f3f73a6c
--- /dev/null
+++ b/kernel/power/swap.c
@@ -0,0 +1,544 @@
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/smp_lock.h>
16#include <linux/file.h>
17#include <linux/utsname.h>
18#include <linux/version.h>
19#include <linux/delay.h>
20#include <linux/bitops.h>
21#include <linux/genhd.h>
22#include <linux/device.h>
23#include <linux/buffer_head.h>
24#include <linux/bio.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
35static struct swsusp_header {
36 char reserved[PAGE_SIZE - 20 - sizeof(swp_entry_t)];
37 swp_entry_t image;
38 char orig_sig[10];
39 char sig[10];
40} __attribute__((packed, aligned(PAGE_SIZE))) swsusp_header;
41
42/*
43 * Saving part...
44 */
45
46static unsigned short root_swap = 0xffff;
47
48static int mark_swapfiles(swp_entry_t start)
49{
50 int error;
51
52 rw_swap_page_sync(READ,
53 swp_entry(root_swap, 0),
54 virt_to_page((unsigned long)&swsusp_header));
55 if (!memcmp("SWAP-SPACE",swsusp_header.sig, 10) ||
56 !memcmp("SWAPSPACE2",swsusp_header.sig, 10)) {
57 memcpy(swsusp_header.orig_sig,swsusp_header.sig, 10);
58 memcpy(swsusp_header.sig,SWSUSP_SIG, 10);
59 swsusp_header.image = start;
60 error = rw_swap_page_sync(WRITE,
61 swp_entry(root_swap, 0),
62 virt_to_page((unsigned long)
63 &swsusp_header));
64 } else {
65 pr_debug("swsusp: Partition is not swap space.\n");
66 error = -ENODEV;
67 }
68 return error;
69}
70
71/**
72 * swsusp_swap_check - check if the resume device is a swap device
73 * and get its index (if so)
74 */
75
76static int swsusp_swap_check(void) /* This is called before saving image */
77{
78 int res = swap_type_of(swsusp_resume_device);
79
80 if (res >= 0) {
81 root_swap = res;
82 return 0;
83 }
84 return res;
85}
86
87/**
88 * write_page - Write one page to given swap location.
89 * @buf: Address we're writing.
90 * @offset: Offset of the swap page we're writing to.
91 */
92
93static int write_page(void *buf, unsigned long offset)
94{
95 swp_entry_t entry;
96 int error = -ENOSPC;
97
98 if (offset) {
99 entry = swp_entry(root_swap, offset);
100 error = rw_swap_page_sync(WRITE, entry, virt_to_page(buf));
101 }
102 return error;
103}
104
105/*
106 * The swap map is a data structure used for keeping track of each page
107 * written to a swap partition. It consists of many swap_map_page
108 * structures that contain each an array of MAP_PAGE_SIZE swap entries.
109 * These structures are stored on the swap and linked together with the
110 * help of the .next_swap member.
111 *
112 * The swap map is created during suspend. The swap map pages are
113 * allocated and populated one at a time, so we only need one memory
114 * page to set up the entire structure.
115 *
116 * During resume we also only need to use one swap_map_page structure
117 * at a time.
118 */
119
120#define MAP_PAGE_ENTRIES (PAGE_SIZE / sizeof(long) - 1)
121
122struct swap_map_page {
123 unsigned long entries[MAP_PAGE_ENTRIES];
124 unsigned long next_swap;
125};
126
127/**
128 * The swap_map_handle structure is used for handling swap in
129 * a file-alike way
130 */
131
132struct swap_map_handle {
133 struct swap_map_page *cur;
134 unsigned long cur_swap;
135 struct bitmap_page *bitmap;
136 unsigned int k;
137};
138
139static void release_swap_writer(struct swap_map_handle *handle)
140{
141 if (handle->cur)
142 free_page((unsigned long)handle->cur);
143 handle->cur = NULL;
144 if (handle->bitmap)
145 free_bitmap(handle->bitmap);
146 handle->bitmap = NULL;
147}
148
149static int get_swap_writer(struct swap_map_handle *handle)
150{
151 handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL);
152 if (!handle->cur)
153 return -ENOMEM;
154 handle->bitmap = alloc_bitmap(count_swap_pages(root_swap, 0));
155 if (!handle->bitmap) {
156 release_swap_writer(handle);
157 return -ENOMEM;
158 }
159 handle->cur_swap = alloc_swap_page(root_swap, handle->bitmap);
160 if (!handle->cur_swap) {
161 release_swap_writer(handle);
162 return -ENOSPC;
163 }
164 handle->k = 0;
165 return 0;
166}
167
168static int swap_write_page(struct swap_map_handle *handle, void *buf)
169{
170 int error;
171 unsigned long offset;
172
173 if (!handle->cur)
174 return -EINVAL;
175 offset = alloc_swap_page(root_swap, handle->bitmap);
176 error = write_page(buf, offset);
177 if (error)
178 return error;
179 handle->cur->entries[handle->k++] = offset;
180 if (handle->k >= MAP_PAGE_ENTRIES) {
181 offset = alloc_swap_page(root_swap, handle->bitmap);
182 if (!offset)
183 return -ENOSPC;
184 handle->cur->next_swap = offset;
185 error = write_page(handle->cur, handle->cur_swap);
186 if (error)
187 return error;
188 memset(handle->cur, 0, PAGE_SIZE);
189 handle->cur_swap = offset;
190 handle->k = 0;
191 }
192 return 0;
193}
194
195static int flush_swap_writer(struct swap_map_handle *handle)
196{
197 if (handle->cur && handle->cur_swap)
198 return write_page(handle->cur, handle->cur_swap);
199 else
200 return -EINVAL;
201}
202
203/**
204 * save_image - save the suspend image data
205 */
206
207static int save_image(struct swap_map_handle *handle,
208 struct snapshot_handle *snapshot,
209 unsigned int nr_pages)
210{
211 unsigned int m;
212 int ret;
213 int error = 0;
214
215 printk("Saving image data pages (%u pages) ... ", nr_pages);
216 m = nr_pages / 100;
217 if (!m)
218 m = 1;
219 nr_pages = 0;
220 do {
221 ret = snapshot_read_next(snapshot, PAGE_SIZE);
222 if (ret > 0) {
223 error = swap_write_page(handle, data_of(*snapshot));
224 if (error)
225 break;
226 if (!(nr_pages % m))
227 printk("\b\b\b\b%3d%%", nr_pages / m);
228 nr_pages++;
229 }
230 } while (ret > 0);
231 if (!error)
232 printk("\b\b\b\bdone\n");
233 return error;
234}
235
236/**
237 * enough_swap - Make sure we have enough swap to save the image.
238 *
239 * Returns TRUE or FALSE after checking the total amount of swap
240 * space avaiable from the resume partition.
241 */
242
243static int enough_swap(unsigned int nr_pages)
244{
245 unsigned int free_swap = count_swap_pages(root_swap, 1);
246
247 pr_debug("swsusp: free swap pages: %u\n", free_swap);
248 return free_swap > (nr_pages + PAGES_FOR_IO +
249 (nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE);
250}
251
252/**
253 * swsusp_write - Write entire image and metadata.
254 *
255 * It is important _NOT_ to umount filesystems at this point. We want
256 * them synced (in case something goes wrong) but we DO not want to mark
257 * filesystem clean: it is not. (And it does not matter, if we resume
258 * correctly, we'll mark system clean, anyway.)
259 */
260
261int swsusp_write(void)
262{
263 struct swap_map_handle handle;
264 struct snapshot_handle snapshot;
265 struct swsusp_info *header;
266 unsigned long start;
267 int error;
268
269 if ((error = swsusp_swap_check())) {
270 printk(KERN_ERR "swsusp: Cannot find swap device, try swapon -a.\n");
271 return error;
272 }
273 memset(&snapshot, 0, sizeof(struct snapshot_handle));
274 error = snapshot_read_next(&snapshot, PAGE_SIZE);
275 if (error < PAGE_SIZE)
276 return error < 0 ? error : -EFAULT;
277 header = (struct swsusp_info *)data_of(snapshot);
278 if (!enough_swap(header->pages)) {
279 printk(KERN_ERR "swsusp: Not enough free swap\n");
280 return -ENOSPC;
281 }
282 error = get_swap_writer(&handle);
283 if (!error) {
284 start = handle.cur_swap;
285 error = swap_write_page(&handle, header);
286 }
287 if (!error)
288 error = save_image(&handle, &snapshot, header->pages - 1);
289 if (!error) {
290 flush_swap_writer(&handle);
291 printk("S");
292 error = mark_swapfiles(swp_entry(root_swap, start));
293 printk("|\n");
294 }
295 if (error)
296 free_all_swap_pages(root_swap, handle.bitmap);
297 release_swap_writer(&handle);
298 return error;
299}
300
301/*
302 * Using bio to read from swap.
303 * This code requires a bit more work than just using buffer heads
304 * but, it is the recommended way for 2.5/2.6.
305 * The following are to signal the beginning and end of I/O. Bios
306 * finish asynchronously, while we want them to happen synchronously.
307 * A simple atomic_t, and a wait loop take care of this problem.
308 */
309
310static atomic_t io_done = ATOMIC_INIT(0);
311
312static int end_io(struct bio *bio, unsigned int num, int err)
313{
314 if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
315 panic("I/O error reading memory image");
316 atomic_set(&io_done, 0);
317 return 0;
318}
319
320static struct block_device *resume_bdev;
321
322/**
323 * submit - submit BIO request.
324 * @rw: READ or WRITE.
325 * @off physical offset of page.
326 * @page: page we're reading or writing.
327 *
328 * Straight from the textbook - allocate and initialize the bio.
329 * If we're writing, make sure the page is marked as dirty.
330 * Then submit it and wait.
331 */
332
333static int submit(int rw, pgoff_t page_off, void *page)
334{
335 int error = 0;
336 struct bio *bio;
337
338 bio = bio_alloc(GFP_ATOMIC, 1);
339 if (!bio)
340 return -ENOMEM;
341 bio->bi_sector = page_off * (PAGE_SIZE >> 9);
342 bio->bi_bdev = resume_bdev;
343 bio->bi_end_io = end_io;
344
345 if (bio_add_page(bio, virt_to_page(page), PAGE_SIZE, 0) < PAGE_SIZE) {
346 printk("swsusp: ERROR: adding page to bio at %ld\n",page_off);
347 error = -EFAULT;
348 goto Done;
349 }
350
351 atomic_set(&io_done, 1);
352 submit_bio(rw | (1 << BIO_RW_SYNC), bio);
353 while (atomic_read(&io_done))
354 yield();
355 if (rw == READ)
356 bio_set_pages_dirty(bio);
357 Done:
358 bio_put(bio);
359 return error;
360}
361
362static int bio_read_page(pgoff_t page_off, void *page)
363{
364 return submit(READ, page_off, page);
365}
366
367static int bio_write_page(pgoff_t page_off, void *page)
368{
369 return submit(WRITE, page_off, page);
370}
371
372/**
373 * The following functions allow us to read data using a swap map
374 * in a file-alike way
375 */
376
377static void release_swap_reader(struct swap_map_handle *handle)
378{
379 if (handle->cur)
380 free_page((unsigned long)handle->cur);
381 handle->cur = NULL;
382}
383
384static int get_swap_reader(struct swap_map_handle *handle,
385 swp_entry_t start)
386{
387 int error;
388
389 if (!swp_offset(start))
390 return -EINVAL;
391 handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_ATOMIC);
392 if (!handle->cur)
393 return -ENOMEM;
394 error = bio_read_page(swp_offset(start), handle->cur);
395 if (error) {
396 release_swap_reader(handle);
397 return error;
398 }
399 handle->k = 0;
400 return 0;
401}
402
403static int swap_read_page(struct swap_map_handle *handle, void *buf)
404{
405 unsigned long offset;
406 int error;
407
408 if (!handle->cur)
409 return -EINVAL;
410 offset = handle->cur->entries[handle->k];
411 if (!offset)
412 return -EFAULT;
413 error = bio_read_page(offset, buf);
414 if (error)
415 return error;
416 if (++handle->k >= MAP_PAGE_ENTRIES) {
417 handle->k = 0;
418 offset = handle->cur->next_swap;
419 if (!offset)
420 release_swap_reader(handle);
421 else
422 error = bio_read_page(offset, handle->cur);
423 }
424 return error;
425}
426
427/**
428 * load_image - load the image using the swap map handle
429 * @handle and the snapshot handle @snapshot
430 * (assume there are @nr_pages pages to load)
431 */
432
433static int load_image(struct swap_map_handle *handle,
434 struct snapshot_handle *snapshot,
435 unsigned int nr_pages)
436{
437 unsigned int m;
438 int ret;
439 int error = 0;
440
441 printk("Loading image data pages (%u pages) ... ", nr_pages);
442 m = nr_pages / 100;
443 if (!m)
444 m = 1;
445 nr_pages = 0;
446 do {
447 ret = snapshot_write_next(snapshot, PAGE_SIZE);
448 if (ret > 0) {
449 error = swap_read_page(handle, data_of(*snapshot));
450 if (error)
451 break;
452 if (!(nr_pages % m))
453 printk("\b\b\b\b%3d%%", nr_pages / m);
454 nr_pages++;
455 }
456 } while (ret > 0);
457 if (!error)
458 printk("\b\b\b\bdone\n");
459 if (!snapshot_image_loaded(snapshot))
460 error = -ENODATA;
461 return error;
462}
463
464int swsusp_read(void)
465{
466 int error;
467 struct swap_map_handle handle;
468 struct snapshot_handle snapshot;
469 struct swsusp_info *header;
470
471 if (IS_ERR(resume_bdev)) {
472 pr_debug("swsusp: block device not initialised\n");
473 return PTR_ERR(resume_bdev);
474 }
475
476 memset(&snapshot, 0, sizeof(struct snapshot_handle));
477 error = snapshot_write_next(&snapshot, PAGE_SIZE);
478 if (error < PAGE_SIZE)
479 return error < 0 ? error : -EFAULT;
480 header = (struct swsusp_info *)data_of(snapshot);
481 error = get_swap_reader(&handle, swsusp_header.image);
482 if (!error)
483 error = swap_read_page(&handle, header);
484 if (!error)
485 error = load_image(&handle, &snapshot, header->pages - 1);
486 release_swap_reader(&handle);
487
488 blkdev_put(resume_bdev);
489
490 if (!error)
491 pr_debug("swsusp: Reading resume file was successful\n");
492 else
493 pr_debug("swsusp: Error %d resuming\n", error);
494 return error;
495}
496
497/**
498 * swsusp_check - Check for swsusp signature in the resume device
499 */
500
501int swsusp_check(void)
502{
503 int error;
504
505 resume_bdev = open_by_devnum(swsusp_resume_device, FMODE_READ);
506 if (!IS_ERR(resume_bdev)) {
507 set_blocksize(resume_bdev, PAGE_SIZE);
508 memset(&swsusp_header, 0, sizeof(swsusp_header));
509 if ((error = bio_read_page(0, &swsusp_header)))
510 return error;
511 if (!memcmp(SWSUSP_SIG, swsusp_header.sig, 10)) {
512 memcpy(swsusp_header.sig, swsusp_header.orig_sig, 10);
513 /* Reset swap signature now */
514 error = bio_write_page(0, &swsusp_header);
515 } else {
516 return -EINVAL;
517 }
518 if (error)
519 blkdev_put(resume_bdev);
520 else
521 pr_debug("swsusp: Signature found, resuming\n");
522 } else {
523 error = PTR_ERR(resume_bdev);
524 }
525
526 if (error)
527 pr_debug("swsusp: Error %d check for resume file\n", error);
528
529 return error;
530}
531
532/**
533 * swsusp_close - close swap device.
534 */
535
536void swsusp_close(void)
537{
538 if (IS_ERR(resume_bdev)) {
539 pr_debug("swsusp: block device not initialised\n");
540 return;
541 }
542
543 blkdev_put(resume_bdev);
544}