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