kernel/power/swap.c

   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
  31 extern char resume_file[];
  32
  33 #define SWSUSP_SIG      "S1SUSPEND"
  34
  35 static 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
  46 static unsigned short root_swap = 0xffff;
  47
  48 static 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
  76 static 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
  93 static 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
 122 struct 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
 132 struct 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
 139 static 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
 149 static 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
 168 static 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
 195 static 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
 207 static 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
 243 static 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
 261 int swsusp_write(void)
 262 {
 263         struct swap_map_handle handle;
 264         struct snapshot_handle snapshot;
 265         struct swsusp_info *header;
 266         int error;
 267
 268         if ((error = swsusp_swap_check())) {
 269                 printk(KERN_ERR "swsusp: Cannot find swap device, try swapon -a.\n");
 270                 return error;
 271         }
 272         memset(&snapshot, 0, sizeof(struct snapshot_handle));
 273         error = snapshot_read_next(&snapshot, PAGE_SIZE);
 274         if (error < PAGE_SIZE)
 275                 return error < 0 ? error : -EFAULT;
 276         header = (struct swsusp_info *)data_of(snapshot);
 277         if (!enough_swap(header->pages)) {
 278                 printk(KERN_ERR "swsusp: Not enough free swap\n");
 279                 return -ENOSPC;
 280         }
 281         error = get_swap_writer(&handle);
 282         if (!error) {
 283                 unsigned long start = handle.cur_swap;
 284                 error = swap_write_page(&handle, header);
 285                 if (!error)
 286                         error = save_image(&handle, &snapshot,
 287                                         header->pages - 1);
 288                 if (!error) {
 289                         flush_swap_writer(&handle);
 290                         printk("S");
 291                         error = mark_swapfiles(swp_entry(root_swap, start));
 292                         printk("|\n");
 293                 }
 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
 310 static atomic_t io_done = ATOMIC_INIT(0);
 311
 312 static int end_io(struct bio *bio, unsigned int num, int err)
 313 {
 314         if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) {
 315                 printk(KERN_ERR "I/O error reading swsusp image.\n");
 316                 return -EIO;
 317         }
 318         atomic_set(&io_done, 0);
 319         return 0;
 320 }
 321
 322 static struct block_device *resume_bdev;
 323
 324 /**
 325  *      submit - submit BIO request.
 326  *      @rw:    READ or WRITE.
 327  *      @off    physical offset of page.
 328  *      @page:  page we're reading or writing.
 329  *
 330  *      Straight from the textbook - allocate and initialize the bio.
 331  *      If we're writing, make sure the page is marked as dirty.
 332  *      Then submit it and wait.
 333  */
 334
 335 static int submit(int rw, pgoff_t page_off, void *page)
 336 {
 337         int error = 0;
 338         struct bio *bio;
 339
 340         bio = bio_alloc(GFP_ATOMIC, 1);
 341         if (!bio)
 342                 return -ENOMEM;
 343         bio->bi_sector = page_off * (PAGE_SIZE >> 9);
 344         bio->bi_bdev = resume_bdev;
 345         bio->bi_end_io = end_io;
 346
 347         if (bio_add_page(bio, virt_to_page(page), PAGE_SIZE, 0) < PAGE_SIZE) {
 348                 printk("swsusp: ERROR: adding page to bio at %ld\n",page_off);
 349                 error = -EFAULT;
 350                 goto Done;
 351         }
 352
 353         atomic_set(&io_done, 1);
 354         submit_bio(rw | (1 << BIO_RW_SYNC), bio);
 355         while (atomic_read(&io_done))
 356                 yield();
 357         if (rw == READ)
 358                 bio_set_pages_dirty(bio);
 359  Done:
 360         bio_put(bio);
 361         return error;
 362 }
 363
 364 static int bio_read_page(pgoff_t page_off, void *page)
 365 {
 366         return submit(READ, page_off, page);
 367 }
 368
 369 static int bio_write_page(pgoff_t page_off, void *page)
 370 {
 371         return submit(WRITE, page_off, page);
 372 }
 373
 374 /**
 375  *      The following functions allow us to read data using a swap map
 376  *      in a file-alike way
 377  */
 378
 379 static void release_swap_reader(struct swap_map_handle *handle)
 380 {
 381         if (handle->cur)
 382                 free_page((unsigned long)handle->cur);
 383         handle->cur = NULL;
 384 }
 385
 386 static int get_swap_reader(struct swap_map_handle *handle,
 387                                       swp_entry_t start)
 388 {
 389         int error;
 390
 391         if (!swp_offset(start))
 392                 return -EINVAL;
 393         handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_ATOMIC);
 394         if (!handle->cur)
 395                 return -ENOMEM;
 396         error = bio_read_page(swp_offset(start), handle->cur);
 397         if (error) {
 398                 release_swap_reader(handle);
 399                 return error;
 400         }
 401         handle->k = 0;
 402         return 0;
 403 }
 404
 405 static int swap_read_page(struct swap_map_handle *handle, void *buf)
 406 {
 407         unsigned long offset;
 408         int error;
 409
 410         if (!handle->cur)
 411                 return -EINVAL;
 412         offset = handle->cur->entries[handle->k];
 413         if (!offset)
 414                 return -EFAULT;
 415         error = bio_read_page(offset, buf);
 416         if (error)
 417                 return error;
 418         if (++handle->k >= MAP_PAGE_ENTRIES) {
 419                 handle->k = 0;
 420                 offset = handle->cur->next_swap;
 421                 if (!offset)
 422                         release_swap_reader(handle);
 423                 else
 424                         error = bio_read_page(offset, handle->cur);
 425         }
 426         return error;
 427 }
 428
 429 /**
 430  *      load_image - load the image using the swap map handle
 431  *      @handle and the snapshot handle @snapshot
 432  *      (assume there are @nr_pages pages to load)
 433  */
 434
 435 static int load_image(struct swap_map_handle *handle,
 436                       struct snapshot_handle *snapshot,
 437                       unsigned int nr_pages)
 438 {
 439         unsigned int m;
 440         int ret;
 441         int error = 0;
 442
 443         printk("Loading image data pages (%u pages) ...     ", nr_pages);
 444         m = nr_pages / 100;
 445         if (!m)
 446                 m = 1;
 447         nr_pages = 0;
 448         do {
 449                 ret = snapshot_write_next(snapshot, PAGE_SIZE);
 450                 if (ret > 0) {
 451                         error = swap_read_page(handle, data_of(*snapshot));
 452                         if (error)
 453                                 break;
 454                         if (!(nr_pages % m))
 455                                 printk("\b\b\b\b%3d%%", nr_pages / m);
 456                         nr_pages++;
 457                 }
 458         } while (ret > 0);
 459         if (!error) {
 460                 printk("\b\b\b\bdone\n");
 461                 if (!snapshot_image_loaded(snapshot))
 462                         error = -ENODATA;
 463         }
 464         return error;
 465 }
 466
 467 int swsusp_read(void)
 468 {
 469         int error;
 470         struct swap_map_handle handle;
 471         struct snapshot_handle snapshot;
 472         struct swsusp_info *header;
 473
 474         if (IS_ERR(resume_bdev)) {
 475                 pr_debug("swsusp: block device not initialised\n");
 476                 return PTR_ERR(resume_bdev);
 477         }
 478
 479         memset(&snapshot, 0, sizeof(struct snapshot_handle));
 480         error = snapshot_write_next(&snapshot, PAGE_SIZE);
 481         if (error < PAGE_SIZE)
 482                 return error < 0 ? error : -EFAULT;
 483         header = (struct swsusp_info *)data_of(snapshot);
 484         error = get_swap_reader(&handle, swsusp_header.image);
 485         if (!error)
 486                 error = swap_read_page(&handle, header);
 487         if (!error)
 488                 error = load_image(&handle, &snapshot, header->pages - 1);
 489         release_swap_reader(&handle);
 490
 491         blkdev_put(resume_bdev);
 492
 493         if (!error)
 494                 pr_debug("swsusp: Reading resume file was successful\n");
 495         else
 496                 pr_debug("swsusp: Error %d resuming\n", error);
 497         return error;
 498 }
 499
 500 /**
 501  *      swsusp_check - Check for swsusp signature in the resume device
 502  */
 503
 504 int swsusp_check(void)
 505 {
 506         int error;
 507
 508         resume_bdev = open_by_devnum(swsusp_resume_device, FMODE_READ);
 509         if (!IS_ERR(resume_bdev)) {
 510                 set_blocksize(resume_bdev, PAGE_SIZE);
 511                 memset(&swsusp_header, 0, sizeof(swsusp_header));
 512                 if ((error = bio_read_page(0, &swsusp_header)))
 513                         return error;
 514                 if (!memcmp(SWSUSP_SIG, swsusp_header.sig, 10)) {
 515                         memcpy(swsusp_header.sig, swsusp_header.orig_sig, 10);
 516                         /* Reset swap signature now */
 517                         error = bio_write_page(0, &swsusp_header);
 518                 } else {
 519                         return -EINVAL;
 520                 }
 521                 if (error)
 522                         blkdev_put(resume_bdev);
 523                 else
 524                         pr_debug("swsusp: Signature found, resuming\n");
 525         } else {
 526                 error = PTR_ERR(resume_bdev);
 527         }
 528
 529         if (error)
 530                 pr_debug("swsusp: Error %d check for resume file\n", error);
 531
 532         return error;
 533 }
 534
 535 /**
 536  *      swsusp_close - close swap device.
 537  */
 538
 539 void swsusp_close(void)
 540 {
 541         if (IS_ERR(resume_bdev)) {
 542                 pr_debug("swsusp: block device not initialised\n");
 543                 return;
 544         }
 545
 546         blkdev_put(resume_bdev);
 547 }