1/* 2 * linux/mm/swapfile.c 3 * 4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds 5 * Swap reorganised 29.12.95, Stephen Tweedie 6 */ 7 8#include <linux/mm.h> 9#include <linux/hugetlb.h> 10#include <linux/mman.h> 11#include <linux/slab.h> 12#include <linux/kernel_stat.h> 13#include <linux/swap.h> 14#include <linux/vmalloc.h> 15#include <linux/pagemap.h> 16#include <linux/namei.h> 17#include <linux/shm.h> 18#include <linux/blkdev.h> 19#include <linux/writeback.h> 20#include <linux/proc_fs.h> 21#include <linux/seq_file.h> 22#include <linux/init.h> 23#include <linux/module.h> 24#include <linux/rmap.h> 25#include <linux/security.h> 26#include <linux/backing-dev.h> 27#include <linux/mutex.h> 28#include <linux/capability.h> 29#include <linux/syscalls.h> 30 31#include <asm/pgtable.h> 32#include <asm/tlbflush.h> 33#include <linux/swapops.h> 34 35DEFINE_SPINLOCK(swap_lock); 36unsigned int nr_swapfiles; 37long total_swap_pages; 38static int swap_overflow; 39 40static const char Bad_file[] = "Bad swap file entry "; 41static const char Unused_file[] = "Unused swap file entry "; 42static const char Bad_offset[] = "Bad swap offset entry "; 43static const char Unused_offset[] = "Unused swap offset entry "; 44 45struct swap_list_t swap_list = {-1, -1}; 46 47static struct swap_info_struct swap_info[MAX_SWAPFILES]; 48 49static DEFINE_MUTEX(swapon_mutex); 50 51/* 52 * We need this because the bdev->unplug_fn can sleep and we cannot 53 * hold swap_lock while calling the unplug_fn. And swap_lock 54 * cannot be turned into a mutex. 55 */ 56static DECLARE_RWSEM(swap_unplug_sem); 57 58void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page) 59{ 60 swp_entry_t entry; 61 62 down_read(&swap_unplug_sem); 63 entry.val = page_private(page); 64 if (PageSwapCache(page)) { 65 struct block_device *bdev = swap_info[swp_type(entry)].bdev; 66 struct backing_dev_info *bdi; 67 68 /* 69 * If the page is removed from swapcache from under us (with a 70 * racy try_to_unuse/swapoff) we need an additional reference 71 * count to avoid reading garbage from page_private(page) above. 72 * If the WARN_ON triggers during a swapoff it maybe the race 73 * condition and it's harmless. However if it triggers without 74 * swapoff it signals a problem. 75 */ 76 WARN_ON(page_count(page) <= 1); 77 78 bdi = bdev->bd_inode->i_mapping->backing_dev_info; 79 blk_run_backing_dev(bdi, page); 80 } 81 up_read(&swap_unplug_sem); 82} 83 84#define SWAPFILE_CLUSTER 256 85#define LATENCY_LIMIT 256 86 87static inline unsigned long scan_swap_map(struct swap_info_struct *si) 88{ 89 unsigned long offset, last_in_cluster; 90 int latency_ration = LATENCY_LIMIT; 91 92 /* 93 * We try to cluster swap pages by allocating them sequentially 94 * in swap. Once we've allocated SWAPFILE_CLUSTER pages this 95 * way, however, we resort to first-free allocation, starting 96 * a new cluster. This prevents us from scattering swap pages 97 * all over the entire swap partition, so that we reduce 98 * overall disk seek times between swap pages. -- sct 99 * But we do now try to find an empty cluster. -Andrea 100 */ 101 102 si->flags += SWP_SCANNING; 103 if (unlikely(!si->cluster_nr)) { 104 si->cluster_nr = SWAPFILE_CLUSTER - 1; 105 if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) 106 goto lowest; 107 spin_unlock(&swap_lock); 108 109 offset = si->lowest_bit; 110 last_in_cluster = offset + SWAPFILE_CLUSTER - 1; 111 112 /* Locate the first empty (unaligned) cluster */ 113 for (; last_in_cluster <= si->highest_bit; offset++) { 114 if (si->swap_map[offset]) 115 last_in_cluster = offset + SWAPFILE_CLUSTER; 116 else if (offset == last_in_cluster) { 117 spin_lock(&swap_lock); 118 si->cluster_next = offset-SWAPFILE_CLUSTER+1; 119 goto cluster; 120 } 121 if (unlikely(--latency_ration < 0)) { 122 cond_resched(); 123 latency_ration = LATENCY_LIMIT; 124 } 125 } 126 spin_lock(&swap_lock); 127 goto lowest; 128 } 129 130 si->cluster_nr--; 131cluster: 132 offset = si->cluster_next; 133 if (offset > si->highest_bit) 134lowest: offset = si->lowest_bit; 135checks: if (!(si->flags & SWP_WRITEOK)) 136 goto no_page; 137 if (!si->highest_bit) 138 goto no_page; 139 if (!si->swap_map[offset]) { 140 if (offset == si->lowest_bit) 141 si->lowest_bit++; 142 if (offset == si->highest_bit) 143 si->highest_bit--; 144 si->inuse_pages++; 145 if (si->inuse_pages == si->pages) { 146 si->lowest_bit = si->max; 147 si->highest_bit = 0; 148 } 149 si->swap_map[offset] = 1; 150 si->cluster_next = offset + 1; 151 si->flags -= SWP_SCANNING; 152 return offset; 153 } 154 155 spin_unlock(&swap_lock); 156 while (++offset <= si->highest_bit) { 157 if (!si->swap_map[offset]) { 158 spin_lock(&swap_lock); 159 goto checks; 160 } 161 if (unlikely(--latency_ration < 0)) { 162 cond_resched(); 163 latency_ration = LATENCY_LIMIT; 164 } 165 } 166 spin_lock(&swap_lock); 167 goto lowest; 168 169no_page: 170 si->flags -= SWP_SCANNING; 171 return 0; 172} 173 174swp_entry_t get_swap_page(void) 175{ 176 struct swap_info_struct *si; 177 pgoff_t offset; 178 int type, next; 179 int wrapped = 0; 180 181 spin_lock(&swap_lock); 182 if (nr_swap_pages <= 0) 183 goto noswap; 184 nr_swap_pages--; 185 186 for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) { 187 si = swap_info + type; 188 next = si->next; 189 if (next < 0 || 190 (!wrapped && si->prio != swap_info[next].prio)) { 191 next = swap_list.head; 192 wrapped++; 193 } 194 195 if (!si->highest_bit) 196 continue; 197 if (!(si->flags & SWP_WRITEOK)) 198 continue; 199 200 swap_list.next = next; 201 offset = scan_swap_map(si); 202 if (offset) { 203 spin_unlock(&swap_lock); 204 return swp_entry(type, offset); 205 } 206 next = swap_list.next; 207 } 208 209 nr_swap_pages++; 210noswap: 211 spin_unlock(&swap_lock); 212 return (swp_entry_t) {0}; 213} 214 215swp_entry_t get_swap_page_of_type(int type) 216{ 217 struct swap_info_struct *si; 218 pgoff_t offset; 219 220 spin_lock(&swap_lock); 221 si = swap_info + type; 222 if (si->flags & SWP_WRITEOK) { 223 nr_swap_pages--; 224 offset = scan_swap_map(si); 225 if (offset) { 226 spin_unlock(&swap_lock); 227 return swp_entry(type, offset); 228 } 229 nr_swap_pages++; 230 } 231 spin_unlock(&swap_lock); 232 return (swp_entry_t) {0}; 233} 234 235static struct swap_info_struct * swap_info_get(swp_entry_t entry) 236{ 237 struct swap_info_struct * p; 238 unsigned long offset, type; 239 240 if (!entry.val) 241 goto out; 242 type = swp_type(entry); 243 if (type >= nr_swapfiles) 244 goto bad_nofile; 245 p = & swap_info[type]; 246 if (!(p->flags & SWP_USED)) 247 goto bad_device; 248 offset = swp_offset(entry); 249 if (offset >= p->max) 250 goto bad_offset; 251 if (!p->swap_map[offset]) 252 goto bad_free; 253 spin_lock(&swap_lock); 254 return p; 255 256bad_free: 257 printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val); 258 goto out; 259bad_offset: 260 printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val); 261 goto out; 262bad_device: 263 printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val); 264 goto out; 265bad_nofile: 266 printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val); 267out: 268 return NULL; 269} 270 271static int swap_entry_free(struct swap_info_struct *p, unsigned long offset) 272{ 273 int count = p->swap_map[offset]; 274 275 if (count < SWAP_MAP_MAX) { 276 count--; 277 p->swap_map[offset] = count; 278 if (!count) { 279 if (offset < p->lowest_bit) 280 p->lowest_bit = offset; 281 if (offset > p->highest_bit) 282 p->highest_bit = offset; 283 if (p->prio > swap_info[swap_list.next].prio) 284 swap_list.next = p - swap_info; 285 nr_swap_pages++; 286 p->inuse_pages--; 287 } 288 } 289 return count; 290} 291 292/* 293 * Caller has made sure that the swapdevice corresponding to entry 294 * is still around or has not been recycled. 295 */ 296void swap_free(swp_entry_t entry) 297{ 298 struct swap_info_struct * p; 299 300 p = swap_info_get(entry); 301 if (p) { 302 swap_entry_free(p, swp_offset(entry)); 303 spin_unlock(&swap_lock); 304 } 305} 306 307/* 308 * How many references to page are currently swapped out? 309 */ 310static inline int page_swapcount(struct page *page) 311{ 312 int count = 0; 313 struct swap_info_struct *p; 314 swp_entry_t entry; 315 316 entry.val = page_private(page); 317 p = swap_info_get(entry); 318 if (p) { 319 /* Subtract the 1 for the swap cache itself */ 320 count = p->swap_map[swp_offset(entry)] - 1; 321 spin_unlock(&swap_lock); 322 } 323 return count; 324} 325 326/* 327 * We can use this swap cache entry directly 328 * if there are no other references to it. 329 */ 330int can_share_swap_page(struct page *page) 331{ 332 int count; 333 334 BUG_ON(!PageLocked(page)); 335 count = page_mapcount(page); 336 if (count <= 1 && PageSwapCache(page)) 337 count += page_swapcount(page); 338 return count == 1; 339} 340 341/* 342 * Work out if there are any other processes sharing this 343 * swap cache page. Free it if you can. Return success. 344 */ 345int remove_exclusive_swap_page(struct page *page) 346{ 347 int retval; 348 struct swap_info_struct * p; 349 swp_entry_t entry; 350 351 BUG_ON(PagePrivate(page)); 352 BUG_ON(!PageLocked(page)); 353 354 if (!PageSwapCache(page)) 355 return 0; 356 if (PageWriteback(page)) 357 return 0; 358 if (page_count(page) != 2) /* 2: us + cache */ 359 return 0; 360 361 entry.val = page_private(page); 362 p = swap_info_get(entry); 363 if (!p) 364 return 0; 365 366 /* Is the only swap cache user the cache itself? */ 367 retval = 0; 368 if (p->swap_map[swp_offset(entry)] == 1) { 369 /* Recheck the page count with the swapcache lock held.. */ 370 write_lock_irq(&swapper_space.tree_lock); 371 if ((page_count(page) == 2) && !PageWriteback(page)) { 372 __delete_from_swap_cache(page); 373 SetPageDirty(page); 374 retval = 1; 375 } 376 write_unlock_irq(&swapper_space.tree_lock); 377 } 378 spin_unlock(&swap_lock); 379 380 if (retval) { 381 swap_free(entry); 382 page_cache_release(page); 383 } 384 385 return retval; 386} 387 388/* 389 * Free the swap entry like above, but also try to 390 * free the page cache entry if it is the last user. 391 */ 392void free_swap_and_cache(swp_entry_t entry) 393{ 394 struct swap_info_struct * p; 395 struct page *page = NULL; 396 397 if (is_migration_entry(entry)) 398 return; 399 400 p = swap_info_get(entry); 401 if (p) { 402 if (swap_entry_free(p, swp_offset(entry)) == 1) { 403 page = find_get_page(&swapper_space, entry.val); 404 if (page && unlikely(TestSetPageLocked(page))) { 405 page_cache_release(page); 406 page = NULL; 407 } 408 } 409 spin_unlock(&swap_lock); 410 } 411 if (page) { 412 int one_user; 413 414 BUG_ON(PagePrivate(page)); 415 one_user = (page_count(page) == 2); 416 /* Only cache user (+us), or swap space full? Free it! */ 417 /* Also recheck PageSwapCache after page is locked (above) */ 418 if (PageSwapCache(page) && !PageWriteback(page) && 419 (one_user || vm_swap_full())) { 420 delete_from_swap_cache(page); 421 SetPageDirty(page); 422 } 423 unlock_page(page); 424 page_cache_release(page); 425 } 426} 427 428#ifdef CONFIG_SOFTWARE_SUSPEND 429/* 430 * Find the swap type that corresponds to given device (if any). 431 * 432 * @offset - number of the PAGE_SIZE-sized block of the device, starting 433 * from 0, in which the swap header is expected to be located. 434 * 435 * This is needed for the suspend to disk (aka swsusp). 436 */ 437int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) 438{ 439 struct block_device *bdev = NULL; 440 int i; 441 442 if (device) 443 bdev = bdget(device); 444 445 spin_lock(&swap_lock); 446 for (i = 0; i < nr_swapfiles; i++) { 447 struct swap_info_struct *sis = swap_info + i; 448 449 if (!(sis->flags & SWP_WRITEOK)) 450 continue; 451 452 if (!bdev) { 453 if (bdev_p) 454 *bdev_p = sis->bdev; 455 456 spin_unlock(&swap_lock); 457 return i; 458 } 459 if (bdev == sis->bdev) { 460 struct swap_extent *se; 461 462 se = list_entry(sis->extent_list.next, 463 struct swap_extent, list); 464 if (se->start_block == offset) { 465 if (bdev_p) 466 *bdev_p = sis->bdev; 467 468 spin_unlock(&swap_lock); 469 bdput(bdev); 470 return i; 471 } 472 } 473 } 474 spin_unlock(&swap_lock); 475 if (bdev) 476 bdput(bdev); 477 478 return -ENODEV; 479} 480 481/* 482 * Return either the total number of swap pages of given type, or the number 483 * of free pages of that type (depending on @free) 484 * 485 * This is needed for software suspend 486 */ 487unsigned int count_swap_pages(int type, int free) 488{ 489 unsigned int n = 0; 490 491 if (type < nr_swapfiles) { 492 spin_lock(&swap_lock); 493 if (swap_info[type].flags & SWP_WRITEOK) { 494 n = swap_info[type].pages; 495 if (free) 496 n -= swap_info[type].inuse_pages; 497 } 498 spin_unlock(&swap_lock); 499 } 500 return n; 501} 502#endif 503 504/* 505 * No need to decide whether this PTE shares the swap entry with others, 506 * just let do_wp_page work it out if a write is requested later - to 507 * force COW, vm_page_prot omits write permission from any private vma. 508 */ 509static void unuse_pte(struct vm_area_struct *vma, pte_t *pte, 510 unsigned long addr, swp_entry_t entry, struct page *page) 511{ 512 inc_mm_counter(vma->vm_mm, anon_rss); 513 get_page(page); 514 set_pte_at(vma->vm_mm, addr, pte, 515 pte_mkold(mk_pte(page, vma->vm_page_prot))); 516 page_add_anon_rmap(page, vma, addr); 517 swap_free(entry); 518 /* 519 * Move the page to the active list so it is not 520 * immediately swapped out again after swapon. 521 */ 522 activate_page(page); 523} 524 525static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, 526 unsigned long addr, unsigned long end, 527 swp_entry_t entry, struct page *page) 528{ 529 pte_t swp_pte = swp_entry_to_pte(entry); 530 pte_t *pte; 531 spinlock_t *ptl; 532 int found = 0; 533 534 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); 535 do { 536 /* 537 * swapoff spends a _lot_ of time in this loop! 538 * Test inline before going to call unuse_pte. 539 */ 540 if (unlikely(pte_same(*pte, swp_pte))) { 541 unuse_pte(vma, pte++, addr, entry, page); 542 found = 1; 543 break; 544 } 545 } while (pte++, addr += PAGE_SIZE, addr != end); 546 pte_unmap_unlock(pte - 1, ptl); 547 return found; 548} 549 550static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, 551 unsigned long addr, unsigned long end, 552 swp_entry_t entry, struct page *page) 553{ 554 pmd_t *pmd; 555 unsigned long next; 556 557 pmd = pmd_offset(pud, addr); 558 do { 559 next = pmd_addr_end(addr, end); 560 if (pmd_none_or_clear_bad(pmd)) 561 continue; 562 if (unuse_pte_range(vma, pmd, addr, next, entry, page)) 563 return 1; 564 } while (pmd++, addr = next, addr != end); 565 return 0; 566} 567 568static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd, 569 unsigned long addr, unsigned long end, 570 swp_entry_t entry, struct page *page) 571{ 572 pud_t *pud; 573 unsigned long next; 574 575 pud = pud_offset(pgd, addr); 576 do { 577 next = pud_addr_end(addr, end); 578 if (pud_none_or_clear_bad(pud)) 579 continue; 580 if (unuse_pmd_range(vma, pud, addr, next, entry, page)) 581 return 1; 582 } while (pud++, addr = next, addr != end); 583 return 0; 584} 585 586static int unuse_vma(struct vm_area_struct *vma, 587 swp_entry_t entry, struct page *page) 588{ 589 pgd_t *pgd; 590 unsigned long addr, end, next; 591 592 if (page->mapping) { 593 addr = page_address_in_vma(page, vma); 594 if (addr == -EFAULT) 595 return 0; 596 else 597 end = addr + PAGE_SIZE; 598 } else { 599 addr = vma->vm_start; 600 end = vma->vm_end; 601 } 602 603 pgd = pgd_offset(vma->vm_mm, addr); 604 do { 605 next = pgd_addr_end(addr, end); 606 if (pgd_none_or_clear_bad(pgd)) 607 continue; 608 if (unuse_pud_range(vma, pgd, addr, next, entry, page)) 609 return 1; 610 } while (pgd++, addr = next, addr != end); 611 return 0; 612} 613 614static int unuse_mm(struct mm_struct *mm, 615 swp_entry_t entry, struct page *page) 616{ 617 struct vm_area_struct *vma; 618 619 if (!down_read_trylock(&mm->mmap_sem)) { 620 /* 621 * Activate page so shrink_cache is unlikely to unmap its 622 * ptes while lock is dropped, so swapoff can make progress. 623 */ 624 activate_page(page); 625 unlock_page(page); 626 down_read(&mm->mmap_sem); 627 lock_page(page); 628 } 629 for (vma = mm->mmap; vma; vma = vma->vm_next) { 630 if (vma->anon_vma && unuse_vma(vma, entry, page)) 631 break; 632 } 633 up_read(&mm->mmap_sem); 634 /* 635 * Currently unuse_mm cannot fail, but leave error handling 636 * at call sites for now, since we change it from time to time. 637 */ 638 return 0; 639} 640 641/* 642 * Scan swap_map from current position to next entry still in use. 643 * Recycle to start on reaching the end, returning 0 when empty. 644 */ 645static unsigned int find_next_to_unuse(struct swap_info_struct *si, 646 unsigned int prev) 647{ 648 unsigned int max = si->max; 649 unsigned int i = prev; 650 int count; 651 652 /* 653 * No need for swap_lock here: we're just looking 654 * for whether an entry is in use, not modifying it; false 655 * hits are okay, and sys_swapoff() has already prevented new 656 * allocations from this area (while holding swap_lock). 657 */ 658 for (;;) { 659 if (++i >= max) { 660 if (!prev) { 661 i = 0; 662 break; 663 } 664 /* 665 * No entries in use at top of swap_map, 666 * loop back to start and recheck there. 667 */ 668 max = prev + 1; 669 prev = 0; 670 i = 1; 671 } 672 count = si->swap_map[i]; 673 if (count && count != SWAP_MAP_BAD) 674 break; 675 } 676 return i; 677} 678 679/* 680 * We completely avoid races by reading each swap page in advance, 681 * and then search for the process using it. All the necessary 682 * page table adjustments can then be made atomically. 683 */ 684static int try_to_unuse(unsigned int type) 685{ 686 struct swap_info_struct * si = &swap_info[type]; 687 struct mm_struct *start_mm; 688 unsigned short *swap_map; 689 unsigned short swcount; 690 struct page *page; 691 swp_entry_t entry; 692 unsigned int i = 0; 693 int retval = 0; 694 int reset_overflow = 0; 695 int shmem; 696 697 /* 698 * When searching mms for an entry, a good strategy is to 699 * start at the first mm we freed the previous entry from 700 * (though actually we don't notice whether we or coincidence 701 * freed the entry). Initialize this start_mm with a hold. 702 * 703 * A simpler strategy would be to start at the last mm we 704 * freed the previous entry from; but that would take less 705 * advantage of mmlist ordering, which clusters forked mms 706 * together, child after parent. If we race with dup_mmap(), we 707 * prefer to resolve parent before child, lest we miss entries 708 * duplicated after we scanned child: using last mm would invert 709 * that. Though it's only a serious concern when an overflowed 710 * swap count is reset from SWAP_MAP_MAX, preventing a rescan. 711 */ 712 start_mm = &init_mm; 713 atomic_inc(&init_mm.mm_users); 714 715 /* 716 * Keep on scanning until all entries have gone. Usually, 717 * one pass through swap_map is enough, but not necessarily: 718 * there are races when an instance of an entry might be missed. 719 */ 720 while ((i = find_next_to_unuse(si, i)) != 0) { 721 if (signal_pending(current)) { 722 retval = -EINTR; 723 break; 724 } 725 726 /* 727 * Get a page for the entry, using the existing swap 728 * cache page if there is one. Otherwise, get a clean 729 * page and read the swap into it. 730 */ 731 swap_map = &si->swap_map[i]; 732 entry = swp_entry(type, i); 733 page = read_swap_cache_async(entry, NULL, 0); 734 if (!page) { 735 /* 736 * Either swap_duplicate() failed because entry 737 * has been freed independently, and will not be 738 * reused since sys_swapoff() already disabled 739 * allocation from here, or alloc_page() failed. 740 */ 741 if (!*swap_map) 742 continue; 743 retval = -ENOMEM; 744 break; 745 } 746 747 /* 748 * Don't hold on to start_mm if it looks like exiting. 749 */ 750 if (atomic_read(&start_mm->mm_users) == 1) { 751 mmput(start_mm); 752 start_mm = &init_mm; 753 atomic_inc(&init_mm.mm_users); 754 } 755 756 /* 757 * Wait for and lock page. When do_swap_page races with 758 * try_to_unuse, do_swap_page can handle the fault much 759 * faster than try_to_unuse can locate the entry. This 760 * apparently redundant "wait_on_page_locked" lets try_to_unuse 761 * defer to do_swap_page in such a case - in some tests, 762 * do_swap_page and try_to_unuse repeatedly compete. 763 */ 764 wait_on_page_locked(page); 765 wait_on_page_writeback(page); 766 lock_page(page); 767 wait_on_page_writeback(page); 768 769 /* 770 * Remove all references to entry. 771 * Whenever we reach init_mm, there's no address space 772 * to search, but use it as a reminder to search shmem. 773 */ 774 shmem = 0; 775 swcount = *swap_map; 776 if (swcount > 1) { 777 if (start_mm == &init_mm) 778 shmem = shmem_unuse(entry, page); 779 else 780 retval = unuse_mm(start_mm, entry, page); 781 } 782 if (*swap_map > 1) { 783 int set_start_mm = (*swap_map >= swcount); 784 struct list_head *p = &start_mm->mmlist; 785 struct mm_struct *new_start_mm = start_mm; 786 struct mm_struct *prev_mm = start_mm; 787 struct mm_struct *mm; 788 789 atomic_inc(&new_start_mm->mm_users); 790 atomic_inc(&prev_mm->mm_users); 791 spin_lock(&mmlist_lock); 792 while (*swap_map > 1 && !retval && 793 (p = p->next) != &start_mm->mmlist) { 794 mm = list_entry(p, struct mm_struct, mmlist); 795 if (!atomic_inc_not_zero(&mm->mm_users)) 796 continue; 797 spin_unlock(&mmlist_lock); 798 mmput(prev_mm); 799 prev_mm = mm; 800 801 cond_resched(); 802 803 swcount = *swap_map; 804 if (swcount <= 1) 805 ; 806 else if (mm == &init_mm) { 807 set_start_mm = 1; 808 shmem = shmem_unuse(entry, page); 809 } else 810 retval = unuse_mm(mm, entry, page); 811 if (set_start_mm && *swap_map < swcount) { 812 mmput(new_start_mm); 813 atomic_inc(&mm->mm_users); 814 new_start_mm = mm; 815 set_start_mm = 0; 816 } 817 spin_lock(&mmlist_lock); 818 } 819 spin_unlock(&mmlist_lock); 820 mmput(prev_mm); 821 mmput(start_mm); 822 start_mm = new_start_mm; 823 } 824 if (retval) { 825 unlock_page(page); 826 page_cache_release(page); 827 break; 828 } 829 830 /* 831 * How could swap count reach 0x7fff when the maximum 832 * pid is 0x7fff, and there's no way to repeat a swap 833 * page within an mm (except in shmem, where it's the 834 * shared object which takes the reference count)? 835 * We believe SWAP_MAP_MAX cannot occur in Linux 2.4. 836 * 837 * If that's wrong, then we should worry more about 838 * exit_mmap() and do_munmap() cases described above: 839 * we might be resetting SWAP_MAP_MAX too early here. 840 * We know "Undead"s can happen, they're okay, so don't 841 * report them; but do report if we reset SWAP_MAP_MAX. 842 */ 843 if (*swap_map == SWAP_MAP_MAX) { 844 spin_lock(&swap_lock); 845 *swap_map = 1; 846 spin_unlock(&swap_lock); 847 reset_overflow = 1; 848 } 849 850 /* 851 * If a reference remains (rare), we would like to leave 852 * the page in the swap cache; but try_to_unmap could 853 * then re-duplicate the entry once we drop page lock, 854 * so we might loop indefinitely; also, that page could 855 * not be swapped out to other storage meanwhile. So: 856 * delete from cache even if there's another reference, 857 * after ensuring that the data has been saved to disk - 858 * since if the reference remains (rarer), it will be 859 * read from disk into another page. Splitting into two 860 * pages would be incorrect if swap supported "shared 861 * private" pages, but they are handled by tmpfs files. 862 * 863 * Note shmem_unuse already deleted a swappage from 864 * the swap cache, unless the move to filepage failed: 865 * in which case it left swappage in cache, lowered its 866 * swap count to pass quickly through the loops above, 867 * and now we must reincrement count to try again later. 868 */ 869 if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) { 870 struct writeback_control wbc = { 871 .sync_mode = WB_SYNC_NONE, 872 }; 873 874 swap_writepage(page, &wbc); 875 lock_page(page); 876 wait_on_page_writeback(page); 877 } 878 if (PageSwapCache(page)) { 879 if (shmem) 880 swap_duplicate(entry); 881 else 882 delete_from_swap_cache(page); 883 } 884 885 /* 886 * So we could skip searching mms once swap count went 887 * to 1, we did not mark any present ptes as dirty: must 888 * mark page dirty so shrink_list will preserve it. 889 */ 890 SetPageDirty(page); 891 unlock_page(page); 892 page_cache_release(page); 893 894 /* 895 * Make sure that we aren't completely killing 896 * interactive performance. 897 */ 898 cond_resched(); 899 } 900 901 mmput(start_mm); 902 if (reset_overflow) { 903 printk(KERN_WARNING "swapoff: cleared swap entry overflow\n"); 904 swap_overflow = 0; 905 } 906 return retval; 907} 908 909/* 910 * After a successful try_to_unuse, if no swap is now in use, we know 911 * we can empty the mmlist. swap_lock must be held on entry and exit. 912 * Note that mmlist_lock nests inside swap_lock, and an mm must be 913 * added to the mmlist just after page_duplicate - before would be racy. 914 */ 915static void drain_mmlist(void) 916{ 917 struct list_head *p, *next; 918 unsigned int i; 919 920 for (i = 0; i < nr_swapfiles; i++) 921 if (swap_info[i].inuse_pages) 922 return; 923 spin_lock(&mmlist_lock); 924 list_for_each_safe(p, next, &init_mm.mmlist) 925 list_del_init(p); 926 spin_unlock(&mmlist_lock); 927} 928 929/* 930 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which 931 * corresponds to page offset `offset'. 932 */ 933sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset) 934{ 935 struct swap_extent *se = sis->curr_swap_extent; 936 struct swap_extent *start_se = se; 937 938 for ( ; ; ) { 939 struct list_head *lh; 940 941 if (se->start_page <= offset && 942 offset < (se->start_page + se->nr_pages)) { 943 return se->start_block + (offset - se->start_page); 944 } 945 lh = se->list.next; 946 if (lh == &sis->extent_list) 947 lh = lh->next; 948 se = list_entry(lh, struct swap_extent, list); 949 sis->curr_swap_extent = se; 950 BUG_ON(se == start_se); /* It *must* be present */ 951 } 952} 953 954#ifdef CONFIG_SOFTWARE_SUSPEND 955/* 956 * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev 957 * corresponding to given index in swap_info (swap type). 958 */ 959sector_t swapdev_block(int swap_type, pgoff_t offset) 960{ 961 struct swap_info_struct *sis; 962 963 if (swap_type >= nr_swapfiles) 964 return 0; 965 966 sis = swap_info + swap_type; 967 return (sis->flags & SWP_WRITEOK) ? map_swap_page(sis, offset) : 0; 968} 969#endif /* CONFIG_SOFTWARE_SUSPEND */ 970 971/* 972 * Free all of a swapdev's extent information 973 */ 974static void destroy_swap_extents(struct swap_info_struct *sis) 975{ 976 while (!list_empty(&sis->extent_list)) { 977 struct swap_extent *se; 978 979 se = list_entry(sis->extent_list.next, 980 struct swap_extent, list); 981 list_del(&se->list); 982 kfree(se); 983 } 984} 985 986/* 987 * Add a block range (and the corresponding page range) into this swapdev's 988 * extent list. The extent list is kept sorted in page order. 989 * 990 * This function rather assumes that it is called in ascending page order. 991 */ 992static int 993add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, 994 unsigned long nr_pages, sector_t start_block) 995{ 996 struct swap_extent *se; 997 struct swap_extent *new_se; 998 struct list_head *lh; 999 1000 lh = sis->extent_list.prev; /* The highest page extent */ 1001 if (lh != &sis->extent_list) { 1002 se = list_entry(lh, struct swap_extent, list); 1003 BUG_ON(se->start_page + se->nr_pages != start_page); 1004 if (se->start_block + se->nr_pages == start_block) { 1005 /* Merge it */ 1006 se->nr_pages += nr_pages; 1007 return 0; 1008 } 1009 } 1010 1011 /* 1012 * No merge. Insert a new extent, preserving ordering. 1013 */ 1014 new_se = kmalloc(sizeof(*se), GFP_KERNEL); 1015 if (new_se == NULL) 1016 return -ENOMEM; 1017 new_se->start_page = start_page; 1018 new_se->nr_pages = nr_pages; 1019 new_se->start_block = start_block; 1020 1021 list_add_tail(&new_se->list, &sis->extent_list); 1022 return 1; 1023} 1024 1025/* 1026 * A `swap extent' is a simple thing which maps a contiguous range of pages 1027 * onto a contiguous range of disk blocks. An ordered list of swap extents 1028 * is built at swapon time and is then used at swap_writepage/swap_readpage 1029 * time for locating where on disk a page belongs. 1030 * 1031 * If the swapfile is an S_ISBLK block device, a single extent is installed. 1032 * This is done so that the main operating code can treat S_ISBLK and S_ISREG 1033 * swap files identically. 1034 * 1035 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap 1036 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK 1037 * swapfiles are handled *identically* after swapon time. 1038 * 1039 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks 1040 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If 1041 * some stray blocks are found which do not fall within the PAGE_SIZE alignment 1042 * requirements, they are simply tossed out - we will never use those blocks 1043 * for swapping. 1044 * 1045 * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This 1046 * prevents root from shooting her foot off by ftruncating an in-use swapfile, 1047 * which will scribble on the fs. 1048 * 1049 * The amount of disk space which a single swap extent represents varies. 1050 * Typically it is in the 1-4 megabyte range. So we can have hundreds of 1051 * extents in the list. To avoid much list walking, we cache the previous 1052 * search location in `curr_swap_extent', and start new searches from there. 1053 * This is extremely effective. The average number of iterations in 1054 * map_swap_page() has been measured at about 0.3 per page. - akpm. 1055 */ 1056static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) 1057{ 1058 struct inode *inode; 1059 unsigned blocks_per_page; 1060 unsigned long page_no; 1061 unsigned blkbits; 1062 sector_t probe_block; 1063 sector_t last_block; 1064 sector_t lowest_block = -1; 1065 sector_t highest_block = 0; 1066 int nr_extents = 0; 1067 int ret; 1068 1069 inode = sis->swap_file->f_mapping->host; 1070 if (S_ISBLK(inode->i_mode)) { 1071 ret = add_swap_extent(sis, 0, sis->max, 0); 1072 *span = sis->pages; 1073 goto done; 1074 } 1075 1076 blkbits = inode->i_blkbits; 1077 blocks_per_page = PAGE_SIZE >> blkbits; 1078 1079 /* 1080 * Map all the blocks into the extent list. This code doesn't try 1081 * to be very smart. 1082 */ 1083 probe_block = 0; 1084 page_no = 0; 1085 last_block = i_size_read(inode) >> blkbits; 1086 while ((probe_block + blocks_per_page) <= last_block && 1087 page_no < sis->max) { 1088 unsigned block_in_page; 1089 sector_t first_block; 1090 1091 first_block = bmap(inode, probe_block); 1092 if (first_block == 0) 1093 goto bad_bmap; 1094 1095 /* 1096 * It must be PAGE_SIZE aligned on-disk 1097 */ 1098 if (first_block & (blocks_per_page - 1)) { 1099 probe_block++; 1100 goto reprobe; 1101 } 1102 1103 for (block_in_page = 1; block_in_page < blocks_per_page; 1104 block_in_page++) { 1105 sector_t block; 1106 1107 block = bmap(inode, probe_block + block_in_page); 1108 if (block == 0) 1109 goto bad_bmap; 1110 if (block != first_block + block_in_page) { 1111 /* Discontiguity */ 1112 probe_block++; 1113 goto reprobe; 1114 } 1115 } 1116 1117 first_block >>= (PAGE_SHIFT - blkbits); 1118 if (page_no) { /* exclude the header page */ 1119 if (first_block < lowest_block) 1120 lowest_block = first_block; 1121 if (first_block > highest_block) 1122 highest_block = first_block; 1123 } 1124 1125 /* 1126 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks 1127 */ 1128 ret = add_swap_extent(sis, page_no, 1, first_block); 1129 if (ret < 0) 1130 goto out; 1131 nr_extents += ret; 1132 page_no++; 1133 probe_block += blocks_per_page; 1134reprobe: 1135 continue; 1136 } 1137 ret = nr_extents; 1138 *span = 1 + highest_block - lowest_block; 1139 if (page_no == 0) 1140 page_no = 1; /* force Empty message */ 1141 sis->max = page_no; 1142 sis->pages = page_no - 1; 1143 sis->highest_bit = page_no - 1; 1144done: 1145 sis->curr_swap_extent = list_entry(sis->extent_list.prev, 1146 struct swap_extent, list); 1147 goto out; 1148bad_bmap: 1149 printk(KERN_ERR "swapon: swapfile has holes\n"); 1150 ret = -EINVAL; 1151out: 1152 return ret; 1153} 1154 1155 1156asmlinkage long sys_swapoff(const char __user * specialfile) 1157{ 1158 struct swap_info_struct * p = NULL; 1159 unsigned short *swap_map; 1160 struct file *swap_file, *victim; 1161 struct address_space *mapping; 1162 struct inode *inode; 1163 char * pathname; 1164 int i, type, prev; 1165 int err; 1166 1167 if (!capable(CAP_SYS_ADMIN)) 1168 return -EPERM; 1169 1170 pathname = getname(specialfile); 1171 err = PTR_ERR(pathname); 1172 if (IS_ERR(pathname)) 1173 goto out; 1174 1175 victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0); 1176 putname(pathname); 1177 err = PTR_ERR(victim); 1178 if (IS_ERR(victim)) 1179 goto out; 1180 1181 mapping = victim->f_mapping; 1182 prev = -1; 1183 spin_lock(&swap_lock); 1184 for (type = swap_list.head; type >= 0; type = swap_info[type].next) { 1185 p = swap_info + type; 1186 if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) { 1187 if (p->swap_file->f_mapping == mapping) 1188 break; 1189 } 1190 prev = type; 1191 } 1192 if (type < 0) { 1193 err = -EINVAL; 1194 spin_unlock(&swap_lock); 1195 goto out_dput; 1196 } 1197 if (!security_vm_enough_memory(p->pages)) 1198 vm_unacct_memory(p->pages); 1199 else { 1200 err = -ENOMEM; 1201 spin_unlock(&swap_lock); 1202 goto out_dput; 1203 } 1204 if (prev < 0) { 1205 swap_list.head = p->next; 1206 } else { 1207 swap_info[prev].next = p->next; 1208 } 1209 if (type == swap_list.next) { 1210 /* just pick something that's safe... */ 1211 swap_list.next = swap_list.head; 1212 } 1213 nr_swap_pages -= p->pages; 1214 total_swap_pages -= p->pages; 1215 p->flags &= ~SWP_WRITEOK; 1216 spin_unlock(&swap_lock); 1217 1218 current->flags |= PF_SWAPOFF; 1219 err = try_to_unuse(type); 1220 current->flags &= ~PF_SWAPOFF; 1221 1222 if (err) { 1223 /* re-insert swap space back into swap_list */ 1224 spin_lock(&swap_lock); 1225 for (prev = -1, i = swap_list.head; i >= 0; prev = i, i = swap_info[i].next) 1226 if (p->prio >= swap_info[i].prio) 1227 break; 1228 p->next = i; 1229 if (prev < 0) 1230 swap_list.head = swap_list.next = p - swap_info; 1231 else 1232 swap_info[prev].next = p - swap_info; 1233 nr_swap_pages += p->pages; 1234 total_swap_pages += p->pages; 1235 p->flags |= SWP_WRITEOK; 1236 spin_unlock(&swap_lock); 1237 goto out_dput; 1238 } 1239 1240 /* wait for any unplug function to finish */ 1241 down_write(&swap_unplug_sem); 1242 up_write(&swap_unplug_sem); 1243 1244 destroy_swap_extents(p); 1245 mutex_lock(&swapon_mutex); 1246 spin_lock(&swap_lock); 1247 drain_mmlist(); 1248 1249 /* wait for anyone still in scan_swap_map */ 1250 p->highest_bit = 0; /* cuts scans short */ 1251 while (p->flags >= SWP_SCANNING) { 1252 spin_unlock(&swap_lock); 1253 schedule_timeout_uninterruptible(1); 1254 spin_lock(&swap_lock); 1255 } 1256 1257 swap_file = p->swap_file; 1258 p->swap_file = NULL; 1259 p->max = 0; 1260 swap_map = p->swap_map; 1261 p->swap_map = NULL; 1262 p->flags = 0; 1263 spin_unlock(&swap_lock); 1264 mutex_unlock(&swapon_mutex); 1265 vfree(swap_map); 1266 inode = mapping->host; 1267 if (S_ISBLK(inode->i_mode)) { 1268 struct block_device *bdev = I_BDEV(inode); 1269 set_blocksize(bdev, p->old_block_size); 1270 bd_release(bdev); 1271 } else { 1272 mutex_lock(&inode->i_mutex); 1273 inode->i_flags &= ~S_SWAPFILE; 1274 mutex_unlock(&inode->i_mutex); 1275 } 1276 filp_close(swap_file, NULL); 1277 err = 0; 1278 1279out_dput: 1280 filp_close(victim, NULL); 1281out: 1282 return err; 1283} 1284 1285#ifdef CONFIG_PROC_FS 1286/* iterator */ 1287static void *swap_start(struct seq_file *swap, loff_t *pos) 1288{ 1289 struct swap_info_struct *ptr = swap_info; 1290 int i; 1291 loff_t l = *pos; 1292 1293 mutex_lock(&swapon_mutex); 1294 1295 if (!l) 1296 return SEQ_START_TOKEN; 1297 1298 for (i = 0; i < nr_swapfiles; i++, ptr++) { 1299 if (!(ptr->flags & SWP_USED) || !ptr->swap_map) 1300 continue; 1301 if (!--l) 1302 return ptr; 1303 } 1304 1305 return NULL; 1306} 1307 1308static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) 1309{ 1310 struct swap_info_struct *ptr; 1311 struct swap_info_struct *endptr = swap_info + nr_swapfiles; 1312 1313 if (v == SEQ_START_TOKEN) 1314 ptr = swap_info; 1315 else { 1316 ptr = v; 1317 ptr++; 1318 } 1319 1320 for (; ptr < endptr; ptr++) { 1321 if (!(ptr->flags & SWP_USED) || !ptr->swap_map) 1322 continue; 1323 ++*pos; 1324 return ptr; 1325 } 1326 1327 return NULL; 1328} 1329 1330static void swap_stop(struct seq_file *swap, void *v) 1331{ 1332 mutex_unlock(&swapon_mutex); 1333} 1334 1335static int swap_show(struct seq_file *swap, void *v) 1336{ 1337 struct swap_info_struct *ptr = v; 1338 struct file *file; 1339 int len; 1340 1341 if (ptr == SEQ_START_TOKEN) { 1342 seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n"); 1343 return 0; 1344 } 1345 1346 file = ptr->swap_file; 1347 len = seq_path(swap, file->f_path.mnt, file->f_path.dentry, " \t\n\\"); 1348 seq_printf(swap, "%*s%s\t%u\t%u\t%d\n", 1349 len < 40 ? 40 - len : 1, " ", 1350 S_ISBLK(file->f_path.dentry->d_inode->i_mode) ? 1351 "partition" : "file\t", 1352 ptr->pages << (PAGE_SHIFT - 10), 1353 ptr->inuse_pages << (PAGE_SHIFT - 10), 1354 ptr->prio); 1355 return 0; 1356} 1357 1358static const struct seq_operations swaps_op = { 1359 .start = swap_start, 1360 .next = swap_next, 1361 .stop = swap_stop, 1362 .show = swap_show 1363}; 1364 1365static int swaps_open(struct inode *inode, struct file *file) 1366{ 1367 return seq_open(file, &swaps_op); 1368} 1369 1370static const struct file_operations proc_swaps_operations = { 1371 .open = swaps_open, 1372 .read = seq_read, 1373 .llseek = seq_lseek, 1374 .release = seq_release, 1375}; 1376 1377static int __init procswaps_init(void) 1378{ 1379 struct proc_dir_entry *entry; 1380 1381 entry = create_proc_entry("swaps", 0, NULL); 1382 if (entry) 1383 entry->proc_fops = &proc_swaps_operations; 1384 return 0; 1385} 1386__initcall(procswaps_init); 1387#endif /* CONFIG_PROC_FS */ 1388 1389/* 1390 * Written 01/25/92 by Simmule Turner, heavily changed by Linus. 1391 * 1392 * The swapon system call 1393 */ 1394asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags) 1395{ 1396 struct swap_info_struct * p; 1397 char *name = NULL; 1398 struct block_device *bdev = NULL; 1399 struct file *swap_file = NULL; 1400 struct address_space *mapping; 1401 unsigned int type; 1402 int i, prev; 1403 int error; 1404 static int least_priority; 1405 union swap_header *swap_header = NULL; 1406 int swap_header_version; 1407 unsigned int nr_good_pages = 0; 1408 int nr_extents = 0; 1409 sector_t span; 1410 unsigned long maxpages = 1; 1411 int swapfilesize; 1412 unsigned short *swap_map; 1413 struct page *page = NULL; 1414 struct inode *inode = NULL; 1415 int did_down = 0; 1416 1417 if (!capable(CAP_SYS_ADMIN)) 1418 return -EPERM; 1419 spin_lock(&swap_lock); 1420 p = swap_info; 1421 for (type = 0 ; type < nr_swapfiles ; type++,p++) 1422 if (!(p->flags & SWP_USED)) 1423 break; 1424 error = -EPERM; 1425 if (type >= MAX_SWAPFILES) { 1426 spin_unlock(&swap_lock); 1427 goto out; 1428 } 1429 if (type >= nr_swapfiles) 1430 nr_swapfiles = type+1; 1431 INIT_LIST_HEAD(&p->extent_list); 1432 p->flags = SWP_USED; 1433 p->swap_file = NULL; 1434 p->old_block_size = 0; 1435 p->swap_map = NULL; 1436 p->lowest_bit = 0; 1437 p->highest_bit = 0; 1438 p->cluster_nr = 0; 1439 p->inuse_pages = 0; 1440 p->next = -1; 1441 if (swap_flags & SWAP_FLAG_PREFER) { 1442 p->prio = 1443 (swap_flags & SWAP_FLAG_PRIO_MASK)>>SWAP_FLAG_PRIO_SHIFT; 1444 } else { 1445 p->prio = --least_priority; 1446 } 1447 spin_unlock(&swap_lock); 1448 name = getname(specialfile); 1449 error = PTR_ERR(name); 1450 if (IS_ERR(name)) { 1451 name = NULL; 1452 goto bad_swap_2; 1453 } 1454 swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0); 1455 error = PTR_ERR(swap_file); 1456 if (IS_ERR(swap_file)) { 1457 swap_file = NULL; 1458 goto bad_swap_2; 1459 } 1460 1461 p->swap_file = swap_file; 1462 mapping = swap_file->f_mapping; 1463 inode = mapping->host; 1464 1465 error = -EBUSY; 1466 for (i = 0; i < nr_swapfiles; i++) { 1467 struct swap_info_struct *q = &swap_info[i]; 1468 1469 if (i == type || !q->swap_file) 1470 continue; 1471 if (mapping == q->swap_file->f_mapping) 1472 goto bad_swap; 1473 } 1474 1475 error = -EINVAL; 1476 if (S_ISBLK(inode->i_mode)) { 1477 bdev = I_BDEV(inode); 1478 error = bd_claim(bdev, sys_swapon); 1479 if (error < 0) { 1480 bdev = NULL; 1481 error = -EINVAL; 1482 goto bad_swap; 1483 } 1484 p->old_block_size = block_size(bdev); 1485 error = set_blocksize(bdev, PAGE_SIZE); 1486 if (error < 0) 1487 goto bad_swap; 1488 p->bdev = bdev; 1489 } else if (S_ISREG(inode->i_mode)) { 1490 p->bdev = inode->i_sb->s_bdev; 1491 mutex_lock(&inode->i_mutex); 1492 did_down = 1; 1493 if (IS_SWAPFILE(inode)) { 1494 error = -EBUSY; 1495 goto bad_swap; 1496 } 1497 } else { 1498 goto bad_swap; 1499 } 1500 1501 swapfilesize = i_size_read(inode) >> PAGE_SHIFT; 1502 1503 /* 1504 * Read the swap header. 1505 */ 1506 if (!mapping->a_ops->readpage) { 1507 error = -EINVAL; 1508 goto bad_swap; 1509 } 1510 page = read_mapping_page(mapping, 0, swap_file); 1511 if (IS_ERR(page)) { 1512 error = PTR_ERR(page); 1513 goto bad_swap; 1514 } 1515 kmap(page); 1516 swap_header = page_address(page); 1517 1518 if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10)) 1519 swap_header_version = 1; 1520 else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10)) 1521 swap_header_version = 2; 1522 else { 1523 printk(KERN_ERR "Unable to find swap-space signature\n"); 1524 error = -EINVAL; 1525 goto bad_swap; 1526 } 1527 1528 switch (swap_header_version) { 1529 case 1: 1530 printk(KERN_ERR "version 0 swap is no longer supported. " 1531 "Use mkswap -v1 %s\n", name); 1532 error = -EINVAL; 1533 goto bad_swap; 1534 case 2: 1535 /* Check the swap header's sub-version and the size of 1536 the swap file and bad block lists */ 1537 if (swap_header->info.version != 1) { 1538 printk(KERN_WARNING 1539 "Unable to handle swap header version %d\n", 1540 swap_header->info.version); 1541 error = -EINVAL; 1542 goto bad_swap; 1543 } 1544 1545 p->lowest_bit = 1; 1546 p->cluster_next = 1; 1547 1548 /* 1549 * Find out how many pages are allowed for a single swap 1550 * device. There are two limiting factors: 1) the number of 1551 * bits for the swap offset in the swp_entry_t type and 1552 * 2) the number of bits in the a swap pte as defined by 1553 * the different architectures. In order to find the 1554 * largest possible bit mask a swap entry with swap type 0 1555 * and swap offset ~0UL is created, encoded to a swap pte, 1556 * decoded to a swp_entry_t again and finally the swap 1557 * offset is extracted. This will mask all the bits from 1558 * the initial ~0UL mask that can't be encoded in either 1559 * the swp_entry_t or the architecture definition of a 1560 * swap pte. 1561 */ 1562 maxpages = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0,~0UL)))) - 1; 1563 if (maxpages > swap_header->info.last_page) 1564 maxpages = swap_header->info.last_page; 1565 p->highest_bit = maxpages - 1; 1566 1567 error = -EINVAL; 1568 if (!maxpages) 1569 goto bad_swap; 1570 if (swapfilesize && maxpages > swapfilesize) { 1571 printk(KERN_WARNING 1572 "Swap area shorter than signature indicates\n"); 1573 goto bad_swap; 1574 } 1575 if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) 1576 goto bad_swap; 1577 if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) 1578 goto bad_swap; 1579 1580 /* OK, set up the swap map and apply the bad block list */ 1581 if (!(p->swap_map = vmalloc(maxpages * sizeof(short)))) { 1582 error = -ENOMEM; 1583 goto bad_swap; 1584 } 1585 1586 error = 0; 1587 memset(p->swap_map, 0, maxpages * sizeof(short)); 1588 for (i = 0; i < swap_header->info.nr_badpages; i++) { 1589 int page_nr = swap_header->info.badpages[i]; 1590 if (page_nr <= 0 || page_nr >= swap_header->info.last_page) 1591 error = -EINVAL; 1592 else 1593 p->swap_map[page_nr] = SWAP_MAP_BAD; 1594 } 1595 nr_good_pages = swap_header->info.last_page - 1596 swap_header->info.nr_badpages - 1597 1 /* header page */; 1598 if (error) 1599 goto bad_swap; 1600 } 1601 1602 if (nr_good_pages) { 1603 p->swap_map[0] = SWAP_MAP_BAD; 1604 p->max = maxpages; 1605 p->pages = nr_good_pages; 1606 nr_extents = setup_swap_extents(p, &span); 1607 if (nr_extents < 0) { 1608 error = nr_extents; 1609 goto bad_swap; 1610 } 1611 nr_good_pages = p->pages; 1612 } 1613 if (!nr_good_pages) { 1614 printk(KERN_WARNING "Empty swap-file\n"); 1615 error = -EINVAL; 1616 goto bad_swap; 1617 } 1618 1619 mutex_lock(&swapon_mutex); 1620 spin_lock(&swap_lock); 1621 p->flags = SWP_ACTIVE; 1622 nr_swap_pages += nr_good_pages; 1623 total_swap_pages += nr_good_pages; 1624 1625 printk(KERN_INFO "Adding %uk swap on %s. " 1626 "Priority:%d extents:%d across:%lluk\n", 1627 nr_good_pages<<(PAGE_SHIFT-10), name, p->prio, 1628 nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10)); 1629 1630 /* insert swap space into swap_list: */ 1631 prev = -1; 1632 for (i = swap_list.head; i >= 0; i = swap_info[i].next) { 1633 if (p->prio >= swap_info[i].prio) { 1634 break; 1635 } 1636 prev = i; 1637 } 1638 p->next = i; 1639 if (prev < 0) { 1640 swap_list.head = swap_list.next = p - swap_info; 1641 } else { 1642 swap_info[prev].next = p - swap_info; 1643 } 1644 spin_unlock(&swap_lock); 1645 mutex_unlock(&swapon_mutex); 1646 error = 0; 1647 goto out; 1648bad_swap: 1649 if (bdev) { 1650 set_blocksize(bdev, p->old_block_size); 1651 bd_release(bdev); 1652 } 1653 destroy_swap_extents(p); 1654bad_swap_2: 1655 spin_lock(&swap_lock); 1656 swap_map = p->swap_map; 1657 p->swap_file = NULL; 1658 p->swap_map = NULL; 1659 p->flags = 0; 1660 if (!(swap_flags & SWAP_FLAG_PREFER)) 1661 ++least_priority; 1662 spin_unlock(&swap_lock); 1663 vfree(swap_map); 1664 if (swap_file) 1665 filp_close(swap_file, NULL); 1666out: 1667 if (page && !IS_ERR(page)) { 1668 kunmap(page); 1669 page_cache_release(page); 1670 } 1671 if (name) 1672 putname(name); 1673 if (did_down) { 1674 if (!error) 1675 inode->i_flags |= S_SWAPFILE; 1676 mutex_unlock(&inode->i_mutex); 1677 } 1678 return error; 1679} 1680 1681void si_swapinfo(struct sysinfo *val) 1682{ 1683 unsigned int i; 1684 unsigned long nr_to_be_unused = 0; 1685 1686 spin_lock(&swap_lock); 1687 for (i = 0; i < nr_swapfiles; i++) { 1688 if (!(swap_info[i].flags & SWP_USED) || 1689 (swap_info[i].flags & SWP_WRITEOK)) 1690 continue; 1691 nr_to_be_unused += swap_info[i].inuse_pages; 1692 } 1693 val->freeswap = nr_swap_pages + nr_to_be_unused; 1694 val->totalswap = total_swap_pages + nr_to_be_unused; 1695 spin_unlock(&swap_lock); 1696} 1697 1698/* 1699 * Verify that a swap entry is valid and increment its swap map count. 1700 * 1701 * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as 1702 * "permanent", but will be reclaimed by the next swapoff. 1703 */ 1704int swap_duplicate(swp_entry_t entry) 1705{ 1706 struct swap_info_struct * p; 1707 unsigned long offset, type; 1708 int result = 0; 1709 1710 if (is_migration_entry(entry)) 1711 return 1; 1712 1713 type = swp_type(entry); 1714 if (type >= nr_swapfiles) 1715 goto bad_file; 1716 p = type + swap_info; 1717 offset = swp_offset(entry); 1718 1719 spin_lock(&swap_lock); 1720 if (offset < p->max && p->swap_map[offset]) { 1721 if (p->swap_map[offset] < SWAP_MAP_MAX - 1) { 1722 p->swap_map[offset]++; 1723 result = 1; 1724 } else if (p->swap_map[offset] <= SWAP_MAP_MAX) { 1725 if (swap_overflow++ < 5) 1726 printk(KERN_WARNING "swap_dup: swap entry overflow\n"); 1727 p->swap_map[offset] = SWAP_MAP_MAX; 1728 result = 1; 1729 } 1730 } 1731 spin_unlock(&swap_lock); 1732out: 1733 return result; 1734 1735bad_file: 1736 printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val); 1737 goto out; 1738} 1739 1740struct swap_info_struct * 1741get_swap_info_struct(unsigned type) 1742{ 1743 return &swap_info[type]; 1744} 1745 1746/* 1747 * swap_lock prevents swap_map being freed. Don't grab an extra 1748 * reference on the swaphandle, it doesn't matter if it becomes unused. 1749 */ 1750int valid_swaphandles(swp_entry_t entry, unsigned long *offset) 1751{ 1752 int our_page_cluster = page_cluster; 1753 int ret = 0, i = 1 << our_page_cluster; 1754 unsigned long toff; 1755 struct swap_info_struct *swapdev = swp_type(entry) + swap_info; 1756 1757 if (!our_page_cluster) /* no readahead */ 1758 return 0; 1759 toff = (swp_offset(entry) >> our_page_cluster) << our_page_cluster; 1760 if (!toff) /* first page is swap header */ 1761 toff++, i--; 1762 *offset = toff; 1763 1764 spin_lock(&swap_lock); 1765 do { 1766 /* Don't read-ahead past the end of the swap area */ 1767 if (toff >= swapdev->max) 1768 break; 1769 /* Don't read in free or bad pages */ 1770 if (!swapdev->swap_map[toff]) 1771 break; 1772 if (swapdev->swap_map[toff] == SWAP_MAP_BAD) 1773 break; 1774 toff++; 1775 ret++; 1776 } while (--i); 1777 spin_unlock(&swap_lock); 1778 return ret; 1779} 1780