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/file.h>
  16 #include <linux/utsname.h>
  17 #include <linux/delay.h>
  18 #include <linux/bitops.h>
  19 #include <linux/genhd.h>
  20 #include <linux/device.h>
  21 #include <linux/buffer_head.h>
  22 #include <linux/bio.h>
  23 #include <linux/blkdev.h>
  24 #include <linux/swap.h>
  25 #include <linux/swapops.h>
  26 #include <linux/pm.h>
  27
  28 #include "power.h"
  29
  30 #define SWSUSP_SIG      "S1SUSPEND"
  31
  32 struct swsusp_header {
  33         char reserved[PAGE_SIZE - 20 - sizeof(sector_t) - sizeof(int)];
  34         sector_t image;
  35         unsigned int flags;     /* Flags to pass to the "boot" kernel */
  36         char    orig_sig[10];
  37         char    sig[10];
  38 } __attribute__((packed));
  39
  40 static struct swsusp_header *swsusp_header;
  41
  42 /*
  43  * General things
  44  */
  45
  46 static unsigned short root_swap = 0xffff;
  47 static struct block_device *resume_bdev;
  48
  49 /**
  50  *      submit - submit BIO request.
  51  *      @rw:    READ or WRITE.
  52  *      @off    physical offset of page.
  53  *      @page:  page we're reading or writing.
  54  *      @bio_chain: list of pending biod (for async reading)
  55  *
  56  *      Straight from the textbook - allocate and initialize the bio.
  57  *      If we're reading, make sure the page is marked as dirty.
  58  *      Then submit it and, if @bio_chain == NULL, wait.
  59  */
  60 static int submit(int rw, pgoff_t page_off, struct page *page,
  61                         struct bio **bio_chain)
  62 {
  63         const int bio_rw = rw | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG);
  64         struct bio *bio;
  65
  66         bio = bio_alloc(__GFP_WAIT | __GFP_HIGH, 1);
  67         if (!bio)
  68                 return -ENOMEM;
  69         bio->bi_sector = page_off * (PAGE_SIZE >> 9);
  70         bio->bi_bdev = resume_bdev;
  71         bio->bi_end_io = end_swap_bio_read;
  72
  73         if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) {
  74                 printk(KERN_ERR "PM: Adding page to bio failed at %ld\n",
  75                         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(bio_rw, 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(bio_rw, bio);
  95         }
  96         return 0;
  97 }
  98
  99 static 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
 104 static 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
 109 static 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
 141 static int mark_swapfiles(sector_t start, unsigned int flags)
 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                 swsusp_header->flags = flags;
 152                 error = bio_write_page(swsusp_resume_block,
 153                                         swsusp_header, NULL);
 154         } else {
 155                 printk(KERN_ERR "PM: Swap header not found!\n");
 156                 error = -ENODEV;
 157         }
 158         return error;
 159 }
 160
 161 /**
 162  *      swsusp_swap_check - check if the resume device is a swap device
 163  *      and get its index (if so)
 164  */
 165
 166 static int swsusp_swap_check(void) /* This is called before saving image */
 167 {
 168         int res;
 169
 170         res = swap_type_of(swsusp_resume_device, swsusp_resume_block,
 171                         &resume_bdev);
 172         if (res < 0)
 173                 return res;
 174
 175         root_swap = res;
 176         res = blkdev_get(resume_bdev, FMODE_WRITE);
 177         if (res)
 178                 return res;
 179
 180         res = set_blocksize(resume_bdev, PAGE_SIZE);
 181         if (res < 0)
 182                 blkdev_put(resume_bdev, FMODE_WRITE);
 183
 184         return res;
 185 }
 186
 187 /**
 188  *      write_page - Write one page to given swap location.
 189  *      @buf:           Address we're writing.
 190  *      @offset:        Offset of the swap page we're writing to.
 191  *      @bio_chain:     Link the next write BIO here
 192  */
 193
 194 static int write_page(void *buf, sector_t offset, struct bio **bio_chain)
 195 {
 196         void *src;
 197
 198         if (!offset)
 199                 return -ENOSPC;
 200
 201         if (bio_chain) {
 202                 src = (void *)__get_free_page(__GFP_WAIT | __GFP_HIGH);
 203                 if (src) {
 204                         memcpy(src, buf, PAGE_SIZE);
 205                 } else {
 206                         WARN_ON_ONCE(1);
 207                         bio_chain = NULL;       /* Go synchronous */
 208                         src = buf;
 209                 }
 210         } else {
 211                 src = buf;
 212         }
 213         return bio_write_page(offset, src, bio_chain);
 214 }
 215
 216 /*
 217  *      The swap map is a data structure used for keeping track of each page
 218  *      written to a swap partition.  It consists of many swap_map_page
 219  *      structures that contain each an array of MAP_PAGE_SIZE swap entries.
 220  *      These structures are stored on the swap and linked together with the
 221  *      help of the .next_swap member.
 222  *
 223  *      The swap map is created during suspend.  The swap map pages are
 224  *      allocated and populated one at a time, so we only need one memory
 225  *      page to set up the entire structure.
 226  *
 227  *      During resume we also only need to use one swap_map_page structure
 228  *      at a time.
 229  */
 230
 231 #define MAP_PAGE_ENTRIES        (PAGE_SIZE / sizeof(sector_t) - 1)
 232
 233 struct swap_map_page {
 234         sector_t entries[MAP_PAGE_ENTRIES];
 235         sector_t next_swap;
 236 };
 237
 238 /**
 239  *      The swap_map_handle structure is used for handling swap in
 240  *      a file-alike way
 241  */
 242
 243 struct swap_map_handle {
 244         struct swap_map_page *cur;
 245         sector_t cur_swap;
 246         unsigned int k;
 247 };
 248
 249 static void release_swap_writer(struct swap_map_handle *handle)
 250 {
 251         if (handle->cur)
 252                 free_page((unsigned long)handle->cur);
 253         handle->cur = NULL;
 254 }
 255
 256 static int get_swap_writer(struct swap_map_handle *handle)
 257 {
 258         handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL);
 259         if (!handle->cur)
 260                 return -ENOMEM;
 261         handle->cur_swap = alloc_swapdev_block(root_swap);
 262         if (!handle->cur_swap) {
 263                 release_swap_writer(handle);
 264                 return -ENOSPC;
 265         }
 266         handle->k = 0;
 267         return 0;
 268 }
 269
 270 static int swap_write_page(struct swap_map_handle *handle, void *buf,
 271                                 struct bio **bio_chain)
 272 {
 273         int error = 0;
 274         sector_t offset;
 275
 276         if (!handle->cur)
 277                 return -EINVAL;
 278         offset = alloc_swapdev_block(root_swap);
 279         error = write_page(buf, offset, bio_chain);
 280         if (error)
 281                 return error;
 282         handle->cur->entries[handle->k++] = offset;
 283         if (handle->k >= MAP_PAGE_ENTRIES) {
 284                 error = wait_on_bio_chain(bio_chain);
 285                 if (error)
 286                         goto out;
 287                 offset = alloc_swapdev_block(root_swap);
 288                 if (!offset)
 289                         return -ENOSPC;
 290                 handle->cur->next_swap = offset;
 291                 error = write_page(handle->cur, handle->cur_swap, NULL);
 292                 if (error)
 293                         goto out;
 294                 memset(handle->cur, 0, PAGE_SIZE);
 295                 handle->cur_swap = offset;
 296                 handle->k = 0;
 297         }
 298  out:
 299         return error;
 300 }
 301
 302 static int flush_swap_writer(struct swap_map_handle *handle)
 303 {
 304         if (handle->cur && handle->cur_swap)
 305                 return write_page(handle->cur, handle->cur_swap, NULL);
 306         else
 307                 return -EINVAL;
 308 }
 309
 310 /**
 311  *      save_image - save the suspend image data
 312  */
 313
 314 static int save_image(struct swap_map_handle *handle,
 315                       struct snapshot_handle *snapshot,
 316                       unsigned int nr_to_write)
 317 {
 318         unsigned int m;
 319         int ret;
 320         int error = 0;
 321         int nr_pages;
 322         int err2;
 323         struct bio *bio;
 324         struct timeval start;
 325         struct timeval stop;
 326
 327         printk(KERN_INFO "PM: Saving image data pages (%u pages) ...     ",
 328                 nr_to_write);
 329         m = nr_to_write / 100;
 330         if (!m)
 331                 m = 1;
 332         nr_pages = 0;
 333         bio = NULL;
 334         do_gettimeofday(&start);
 335         do {
 336                 ret = snapshot_read_next(snapshot, PAGE_SIZE);
 337                 if (ret > 0) {
 338                         error = swap_write_page(handle, data_of(*snapshot),
 339                                                 &bio);
 340                         if (error)
 341                                 break;
 342                         if (!(nr_pages % m))
 343                                 printk("\b\b\b\b%3d%%", nr_pages / m);
 344                         nr_pages++;
 345                 }
 346         } while (ret > 0);
 347         err2 = wait_on_bio_chain(&bio);
 348         do_gettimeofday(&stop);
 349         if (!error)
 350                 error = err2;
 351         if (!error)
 352                 printk("\b\b\b\bdone\n");
 353         swsusp_show_speed(&start, &stop, nr_to_write, "Wrote");
 354         return error;
 355 }
 356
 357 /**
 358  *      enough_swap - Make sure we have enough swap to save the image.
 359  *
 360  *      Returns TRUE or FALSE after checking the total amount of swap
 361  *      space avaiable from the resume partition.
 362  */
 363
 364 static int enough_swap(unsigned int nr_pages)
 365 {
 366         unsigned int free_swap = count_swap_pages(root_swap, 1);
 367
 368         pr_debug("PM: Free swap pages: %u\n", free_swap);
 369         return free_swap > nr_pages + PAGES_FOR_IO;
 370 }
 371
 372 /**
 373  *      swsusp_write - Write entire image and metadata.
 374  *      @flags: flags to pass to the "boot" kernel in the image header
 375  *
 376  *      It is important _NOT_ to umount filesystems at this point. We want
 377  *      them synced (in case something goes wrong) but we DO not want to mark
 378  *      filesystem clean: it is not. (And it does not matter, if we resume
 379  *      correctly, we'll mark system clean, anyway.)
 380  */
 381
 382 int swsusp_write(unsigned int flags)
 383 {
 384         struct swap_map_handle handle;
 385         struct snapshot_handle snapshot;
 386         struct swsusp_info *header;
 387         int error;
 388
 389         error = swsusp_swap_check();
 390         if (error) {
 391                 printk(KERN_ERR "PM: Cannot find swap device, try "
 392                                 "swapon -a.\n");
 393                 return error;
 394         }
 395         memset(&snapshot, 0, sizeof(struct snapshot_handle));
 396         error = snapshot_read_next(&snapshot, PAGE_SIZE);
 397         if (error < PAGE_SIZE) {
 398                 if (error >= 0)
 399                         error = -EFAULT;
 400
 401                 goto out;
 402         }
 403         header = (struct swsusp_info *)data_of(snapshot);
 404         if (!enough_swap(header->pages)) {
 405                 printk(KERN_ERR "PM: Not enough free swap\n");
 406                 error = -ENOSPC;
 407                 goto out;
 408         }
 409         error = get_swap_writer(&handle);
 410         if (!error) {
 411                 sector_t start = handle.cur_swap;
 412
 413                 error = swap_write_page(&handle, header, NULL);
 414                 if (!error)
 415                         error = save_image(&handle, &snapshot,
 416                                         header->pages - 1);
 417
 418                 if (!error) {
 419                         flush_swap_writer(&handle);
 420                         printk(KERN_INFO "PM: S");
 421                         error = mark_swapfiles(start, flags);
 422                         printk("|\n");
 423                 }
 424         }
 425         if (error)
 426                 free_all_swap_pages(root_swap);
 427
 428         release_swap_writer(&handle);
 429  out:
 430         swsusp_close(FMODE_WRITE);
 431         return error;
 432 }
 433
 434 /**
 435  *      The following functions allow us to read data using a swap map
 436  *      in a file-alike way
 437  */
 438
 439 static void release_swap_reader(struct swap_map_handle *handle)
 440 {
 441         if (handle->cur)
 442                 free_page((unsigned long)handle->cur);
 443         handle->cur = NULL;
 444 }
 445
 446 static int get_swap_reader(struct swap_map_handle *handle, sector_t start)
 447 {
 448         int error;
 449
 450         if (!start)
 451                 return -EINVAL;
 452
 453         handle->cur = (struct swap_map_page *)get_zeroed_page(__GFP_WAIT | __GFP_HIGH);
 454         if (!handle->cur)
 455                 return -ENOMEM;
 456
 457         error = bio_read_page(start, handle->cur, NULL);
 458         if (error) {
 459                 release_swap_reader(handle);
 460                 return error;
 461         }
 462         handle->k = 0;
 463         return 0;
 464 }
 465
 466 static int swap_read_page(struct swap_map_handle *handle, void *buf,
 467                                 struct bio **bio_chain)
 468 {
 469         sector_t offset;
 470         int error;
 471
 472         if (!handle->cur)
 473                 return -EINVAL;
 474         offset = handle->cur->entries[handle->k];
 475         if (!offset)
 476                 return -EFAULT;
 477         error = bio_read_page(offset, buf, bio_chain);
 478         if (error)
 479                 return error;
 480         if (++handle->k >= MAP_PAGE_ENTRIES) {
 481                 error = wait_on_bio_chain(bio_chain);
 482                 handle->k = 0;
 483                 offset = handle->cur->next_swap;
 484                 if (!offset)
 485                         release_swap_reader(handle);
 486                 else if (!error)
 487                         error = bio_read_page(offset, handle->cur, NULL);
 488         }
 489         return error;
 490 }
 491
 492 /**
 493  *      load_image - load the image using the swap map handle
 494  *      @handle and the snapshot handle @snapshot
 495  *      (assume there are @nr_pages pages to load)
 496  */
 497
 498 static int load_image(struct swap_map_handle *handle,
 499                       struct snapshot_handle *snapshot,
 500                       unsigned int nr_to_read)
 501 {
 502         unsigned int m;
 503         int error = 0;
 504         struct timeval start;
 505         struct timeval stop;
 506         struct bio *bio;
 507         int err2;
 508         unsigned nr_pages;
 509
 510         printk(KERN_INFO "PM: Loading image data pages (%u pages) ...     ",
 511                 nr_to_read);
 512         m = nr_to_read / 100;
 513         if (!m)
 514                 m = 1;
 515         nr_pages = 0;
 516         bio = NULL;
 517         do_gettimeofday(&start);
 518         for ( ; ; ) {
 519                 error = snapshot_write_next(snapshot, PAGE_SIZE);
 520                 if (error <= 0)
 521                         break;
 522                 error = swap_read_page(handle, data_of(*snapshot), &bio);
 523                 if (error)
 524                         break;
 525                 if (snapshot->sync_read)
 526                         error = wait_on_bio_chain(&bio);
 527                 if (error)
 528                         break;
 529                 if (!(nr_pages % m))
 530                         printk("\b\b\b\b%3d%%", nr_pages / m);
 531                 nr_pages++;
 532         }
 533         err2 = wait_on_bio_chain(&bio);
 534         do_gettimeofday(&stop);
 535         if (!error)
 536                 error = err2;
 537         if (!error) {
 538                 printk("\b\b\b\bdone\n");
 539                 snapshot_write_finalize(snapshot);
 540                 if (!snapshot_image_loaded(snapshot))
 541                         error = -ENODATA;
 542         }
 543         swsusp_show_speed(&start, &stop, nr_to_read, "Read");
 544         return error;
 545 }
 546
 547 /**
 548  *      swsusp_read - read the hibernation image.
 549  *      @flags_p: flags passed by the "frozen" kernel in the image header should
 550  *                be written into this memeory location
 551  */
 552
 553 int swsusp_read(unsigned int *flags_p)
 554 {
 555         int error;
 556         struct swap_map_handle handle;
 557         struct snapshot_handle snapshot;
 558         struct swsusp_info *header;
 559
 560         *flags_p = swsusp_header->flags;
 561         if (IS_ERR(resume_bdev)) {
 562                 pr_debug("PM: Image device not initialised\n");
 563                 return PTR_ERR(resume_bdev);
 564         }
 565
 566         memset(&snapshot, 0, sizeof(struct snapshot_handle));
 567         error = snapshot_write_next(&snapshot, PAGE_SIZE);
 568         if (error < PAGE_SIZE)
 569                 return error < 0 ? error : -EFAULT;
 570         header = (struct swsusp_info *)data_of(snapshot);
 571         error = get_swap_reader(&handle, swsusp_header->image);
 572         if (!error)
 573                 error = swap_read_page(&handle, header, NULL);
 574         if (!error)
 575                 error = load_image(&handle, &snapshot, header->pages - 1);
 576         release_swap_reader(&handle);
 577
 578         blkdev_put(resume_bdev, FMODE_READ);
 579
 580         if (!error)
 581                 pr_debug("PM: Image successfully loaded\n");
 582         else
 583                 pr_debug("PM: Error %d resuming\n", error);
 584         return error;
 585 }
 586
 587 /**
 588  *      swsusp_check - Check for swsusp signature in the resume device
 589  */
 590
 591 int swsusp_check(void)
 592 {
 593         int error;
 594
 595         resume_bdev = open_by_devnum(swsusp_resume_device, FMODE_READ);
 596         if (!IS_ERR(resume_bdev)) {
 597                 set_blocksize(resume_bdev, PAGE_SIZE);
 598                 memset(swsusp_header, 0, PAGE_SIZE);
 599                 error = bio_read_page(swsusp_resume_block,
 600                                         swsusp_header, NULL);
 601                 if (error)
 602                         return error;
 603
 604                 if (!memcmp(SWSUSP_SIG, swsusp_header->sig, 10)) {
 605                         memcpy(swsusp_header->sig, swsusp_header->orig_sig, 10);
 606                         /* Reset swap signature now */
 607                         error = bio_write_page(swsusp_resume_block,
 608                                                 swsusp_header, NULL);
 609                 } else {
 610                         return -EINVAL;
 611                 }
 612                 if (error)
 613                         blkdev_put(resume_bdev, FMODE_READ);
 614                 else
 615                         pr_debug("PM: Signature found, resuming\n");
 616         } else {
 617                 error = PTR_ERR(resume_bdev);
 618         }
 619
 620         if (error)
 621                 pr_debug("PM: Error %d checking image file\n", error);
 622
 623         return error;
 624 }
 625
 626 /**
 627  *      swsusp_close - close swap device.
 628  */
 629
 630 void swsusp_close(fmode_t mode)
 631 {
 632         if (IS_ERR(resume_bdev)) {
 633                 pr_debug("PM: Image device not initialised\n");
 634                 return;
 635         }
 636
 637         blkdev_put(resume_bdev, mode);
 638 }
 639
 640 static int swsusp_header_init(void)
 641 {
 642         swsusp_header = (struct swsusp_header*) __get_free_page(GFP_KERNEL);
 643         if (!swsusp_header)
 644                 panic("Could not allocate memory for swsusp_header\n");
 645         return 0;
 646 }
 647
 648 core_initcall(swsusp_header_init);