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/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>
31 extern char resume_file
[];
33 #define SWSUSP_SIG "S1SUSPEND"
35 static struct swsusp_header
{
36 char reserved
[PAGE_SIZE
- 20 - sizeof(swp_entry_t
)];
40 } __attribute__((packed
, aligned(PAGE_SIZE
))) swsusp_header
;
46 static unsigned short root_swap
= 0xffff;
48 static int mark_swapfiles(swp_entry_t start
)
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)
65 pr_debug("swsusp: Partition is not swap space.\n");
72 * swsusp_swap_check - check if the resume device is a swap device
73 * and get its index (if so)
76 static int swsusp_swap_check(void) /* This is called before saving image */
78 int res
= swap_type_of(swsusp_resume_device
);
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.
93 static int write_page(void *buf
, unsigned long offset
)
99 entry
= swp_entry(root_swap
, offset
);
100 error
= rw_swap_page_sync(WRITE
, entry
, virt_to_page(buf
));
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.
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.
116 * During resume we also only need to use one swap_map_page structure
120 #define MAP_PAGE_ENTRIES (PAGE_SIZE / sizeof(long) - 1)
122 struct swap_map_page
{
123 unsigned long entries
[MAP_PAGE_ENTRIES
];
124 unsigned long next_swap
;
128 * The swap_map_handle structure is used for handling swap in
132 struct swap_map_handle
{
133 struct swap_map_page
*cur
;
134 unsigned long cur_swap
;
135 struct bitmap_page
*bitmap
;
139 static void release_swap_writer(struct swap_map_handle
*handle
)
142 free_page((unsigned long)handle
->cur
);
145 free_bitmap(handle
->bitmap
);
146 handle
->bitmap
= NULL
;
149 static int get_swap_writer(struct swap_map_handle
*handle
)
151 handle
->cur
= (struct swap_map_page
*)get_zeroed_page(GFP_KERNEL
);
154 handle
->bitmap
= alloc_bitmap(count_swap_pages(root_swap
, 0));
155 if (!handle
->bitmap
) {
156 release_swap_writer(handle
);
159 handle
->cur_swap
= alloc_swap_page(root_swap
, handle
->bitmap
);
160 if (!handle
->cur_swap
) {
161 release_swap_writer(handle
);
168 static int swap_write_page(struct swap_map_handle
*handle
, void *buf
)
171 unsigned long offset
;
175 offset
= alloc_swap_page(root_swap
, handle
->bitmap
);
176 error
= write_page(buf
, offset
);
179 handle
->cur
->entries
[handle
->k
++] = offset
;
180 if (handle
->k
>= MAP_PAGE_ENTRIES
) {
181 offset
= alloc_swap_page(root_swap
, handle
->bitmap
);
184 handle
->cur
->next_swap
= offset
;
185 error
= write_page(handle
->cur
, handle
->cur_swap
);
188 memset(handle
->cur
, 0, PAGE_SIZE
);
189 handle
->cur_swap
= offset
;
195 static int flush_swap_writer(struct swap_map_handle
*handle
)
197 if (handle
->cur
&& handle
->cur_swap
)
198 return write_page(handle
->cur
, handle
->cur_swap
);
204 * save_image - save the suspend image data
207 static int save_image(struct swap_map_handle
*handle
,
208 struct snapshot_handle
*snapshot
,
209 unsigned int nr_pages
)
215 printk("Saving image data pages (%u pages) ... ", nr_pages
);
221 ret
= snapshot_read_next(snapshot
, PAGE_SIZE
);
223 error
= swap_write_page(handle
, data_of(*snapshot
));
227 printk("\b\b\b\b%3d%%", nr_pages
/ m
);
232 printk("\b\b\b\bdone\n");
237 * enough_swap - Make sure we have enough swap to save the image.
239 * Returns TRUE or FALSE after checking the total amount of swap
240 * space avaiable from the resume partition.
243 static int enough_swap(unsigned int nr_pages
)
245 unsigned int free_swap
= count_swap_pages(root_swap
, 1);
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
);
253 * swsusp_write - Write entire image and metadata.
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.)
261 int swsusp_write(void)
263 struct swap_map_handle handle
;
264 struct snapshot_handle snapshot
;
265 struct swsusp_info
*header
;
269 if ((error
= swsusp_swap_check())) {
270 printk(KERN_ERR
"swsusp: Cannot find swap device, try swapon -a.\n");
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");
282 error
= get_swap_writer(&handle
);
284 start
= handle
.cur_swap
;
285 error
= swap_write_page(&handle
, header
);
288 error
= save_image(&handle
, &snapshot
, header
->pages
- 1);
290 flush_swap_writer(&handle
);
292 error
= mark_swapfiles(swp_entry(root_swap
, start
));
296 free_all_swap_pages(root_swap
, handle
.bitmap
);
297 release_swap_writer(&handle
);
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.
310 static atomic_t io_done
= ATOMIC_INIT(0);
312 static int end_io(struct bio
*bio
, unsigned int num
, int err
)
314 if (!test_bit(BIO_UPTODATE
, &bio
->bi_flags
))
315 panic("I/O error reading memory image");
316 atomic_set(&io_done
, 0);
320 static struct block_device
*resume_bdev
;
323 * submit - submit BIO request.
324 * @rw: READ or WRITE.
325 * @off physical offset of page.
326 * @page: page we're reading or writing.
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.
333 static int submit(int rw
, pgoff_t page_off
, void *page
)
338 bio
= bio_alloc(GFP_ATOMIC
, 1);
341 bio
->bi_sector
= page_off
* (PAGE_SIZE
>> 9);
342 bio
->bi_bdev
= resume_bdev
;
343 bio
->bi_end_io
= end_io
;
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
);
351 atomic_set(&io_done
, 1);
352 submit_bio(rw
| (1 << BIO_RW_SYNC
), bio
);
353 while (atomic_read(&io_done
))
356 bio_set_pages_dirty(bio
);
362 static int bio_read_page(pgoff_t page_off
, void *page
)
364 return submit(READ
, page_off
, page
);
367 static int bio_write_page(pgoff_t page_off
, void *page
)
369 return submit(WRITE
, page_off
, page
);
373 * The following functions allow us to read data using a swap map
374 * in a file-alike way
377 static void release_swap_reader(struct swap_map_handle
*handle
)
380 free_page((unsigned long)handle
->cur
);
384 static int get_swap_reader(struct swap_map_handle
*handle
,
389 if (!swp_offset(start
))
391 handle
->cur
= (struct swap_map_page
*)get_zeroed_page(GFP_ATOMIC
);
394 error
= bio_read_page(swp_offset(start
), handle
->cur
);
396 release_swap_reader(handle
);
403 static int swap_read_page(struct swap_map_handle
*handle
, void *buf
)
405 unsigned long offset
;
410 offset
= handle
->cur
->entries
[handle
->k
];
413 error
= bio_read_page(offset
, buf
);
416 if (++handle
->k
>= MAP_PAGE_ENTRIES
) {
418 offset
= handle
->cur
->next_swap
;
420 release_swap_reader(handle
);
422 error
= bio_read_page(offset
, handle
->cur
);
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)
433 static int load_image(struct swap_map_handle
*handle
,
434 struct snapshot_handle
*snapshot
,
435 unsigned int nr_pages
)
441 printk("Loading image data pages (%u pages) ... ", nr_pages
);
447 ret
= snapshot_write_next(snapshot
, PAGE_SIZE
);
449 error
= swap_read_page(handle
, data_of(*snapshot
));
453 printk("\b\b\b\b%3d%%", nr_pages
/ m
);
458 printk("\b\b\b\bdone\n");
459 if (!snapshot_image_loaded(snapshot
))
464 int swsusp_read(void)
467 struct swap_map_handle handle
;
468 struct snapshot_handle snapshot
;
469 struct swsusp_info
*header
;
471 if (IS_ERR(resume_bdev
)) {
472 pr_debug("swsusp: block device not initialised\n");
473 return PTR_ERR(resume_bdev
);
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
);
483 error
= swap_read_page(&handle
, header
);
485 error
= load_image(&handle
, &snapshot
, header
->pages
- 1);
486 release_swap_reader(&handle
);
488 blkdev_put(resume_bdev
);
491 pr_debug("swsusp: Reading resume file was successful\n");
493 pr_debug("swsusp: Error %d resuming\n", error
);
498 * swsusp_check - Check for swsusp signature in the resume device
501 int swsusp_check(void)
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
)))
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
);
519 blkdev_put(resume_bdev
);
521 pr_debug("swsusp: Signature found, resuming\n");
523 error
= PTR_ERR(resume_bdev
);
527 pr_debug("swsusp: Error %d check for resume file\n", error
);
533 * swsusp_close - close swap device.
536 void swsusp_close(void)
538 if (IS_ERR(resume_bdev
)) {
539 pr_debug("swsusp: block device not initialised\n");
543 blkdev_put(resume_bdev
);