swapfile.c revision 6eb396dc4a9781c5e7951143ab56ce5710687ab3
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 34DEFINE_SPINLOCK(swaplock); 35unsigned int nr_swapfiles; 36long total_swap_pages; 37static int swap_overflow; 38 39EXPORT_SYMBOL(total_swap_pages); 40 41static const char Bad_file[] = "Bad swap file entry "; 42static const char Unused_file[] = "Unused swap file entry "; 43static const char Bad_offset[] = "Bad swap offset entry "; 44static const char Unused_offset[] = "Unused swap offset entry "; 45 46struct swap_list_t swap_list = {-1, -1}; 47 48struct swap_info_struct swap_info[MAX_SWAPFILES]; 49 50static DECLARE_MUTEX(swapon_sem); 51 52/* 53 * We need this because the bdev->unplug_fn can sleep and we cannot 54 * hold swap_list_lock while calling the unplug_fn. And swap_list_lock 55 * cannot be turned into a semaphore. 56 */ 57static DECLARE_RWSEM(swap_unplug_sem); 58 59#define SWAPFILE_CLUSTER 256 60 61void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page) 62{ 63 swp_entry_t entry; 64 65 down_read(&swap_unplug_sem); 66 entry.val = page->private; 67 if (PageSwapCache(page)) { 68 struct block_device *bdev = swap_info[swp_type(entry)].bdev; 69 struct backing_dev_info *bdi; 70 71 /* 72 * If the page is removed from swapcache from under us (with a 73 * racy try_to_unuse/swapoff) we need an additional reference 74 * count to avoid reading garbage from page->private above. If 75 * the WARN_ON triggers during a swapoff it maybe the race 76 * condition and it's harmless. However if it triggers without 77 * swapoff it signals a problem. 78 */ 79 WARN_ON(page_count(page) <= 1); 80 81 bdi = bdev->bd_inode->i_mapping->backing_dev_info; 82 blk_run_backing_dev(bdi, page); 83 } 84 up_read(&swap_unplug_sem); 85} 86 87static inline unsigned long scan_swap_map(struct swap_info_struct *si) 88{ 89 unsigned long offset; 90 /* 91 * We try to cluster swap pages by allocating them 92 * sequentially in swap. Once we've allocated 93 * SWAPFILE_CLUSTER pages this way, however, we resort to 94 * first-free allocation, starting a new cluster. This 95 * prevents us from scattering swap pages all over the entire 96 * swap partition, so that we reduce overall disk seek times 97 * between swap pages. -- sct */ 98 if (si->cluster_nr) { 99 while (si->cluster_next <= si->highest_bit) { 100 offset = si->cluster_next++; 101 if (si->swap_map[offset]) 102 continue; 103 si->cluster_nr--; 104 goto got_page; 105 } 106 } 107 si->cluster_nr = SWAPFILE_CLUSTER; 108 109 /* try to find an empty (even not aligned) cluster. */ 110 offset = si->lowest_bit; 111 check_next_cluster: 112 if (offset+SWAPFILE_CLUSTER-1 <= si->highest_bit) 113 { 114 unsigned long nr; 115 for (nr = offset; nr < offset+SWAPFILE_CLUSTER; nr++) 116 if (si->swap_map[nr]) 117 { 118 offset = nr+1; 119 goto check_next_cluster; 120 } 121 /* We found a completly empty cluster, so start 122 * using it. 123 */ 124 goto got_page; 125 } 126 /* No luck, so now go finegrined as usual. -Andrea */ 127 for (offset = si->lowest_bit; offset <= si->highest_bit ; offset++) { 128 if (si->swap_map[offset]) 129 continue; 130 si->lowest_bit = offset+1; 131 got_page: 132 if (offset == si->lowest_bit) 133 si->lowest_bit++; 134 if (offset == si->highest_bit) 135 si->highest_bit--; 136 if (si->lowest_bit > si->highest_bit) { 137 si->lowest_bit = si->max; 138 si->highest_bit = 0; 139 } 140 si->swap_map[offset] = 1; 141 si->inuse_pages++; 142 nr_swap_pages--; 143 si->cluster_next = offset+1; 144 return offset; 145 } 146 si->lowest_bit = si->max; 147 si->highest_bit = 0; 148 return 0; 149} 150 151swp_entry_t get_swap_page(void) 152{ 153 struct swap_info_struct * p; 154 unsigned long offset; 155 swp_entry_t entry; 156 int type, wrapped = 0; 157 158 entry.val = 0; /* Out of memory */ 159 swap_list_lock(); 160 type = swap_list.next; 161 if (type < 0) 162 goto out; 163 if (nr_swap_pages <= 0) 164 goto out; 165 166 while (1) { 167 p = &swap_info[type]; 168 if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) { 169 swap_device_lock(p); 170 offset = scan_swap_map(p); 171 swap_device_unlock(p); 172 if (offset) { 173 entry = swp_entry(type,offset); 174 type = swap_info[type].next; 175 if (type < 0 || 176 p->prio != swap_info[type].prio) { 177 swap_list.next = swap_list.head; 178 } else { 179 swap_list.next = type; 180 } 181 goto out; 182 } 183 } 184 type = p->next; 185 if (!wrapped) { 186 if (type < 0 || p->prio != swap_info[type].prio) { 187 type = swap_list.head; 188 wrapped = 1; 189 } 190 } else 191 if (type < 0) 192 goto out; /* out of swap space */ 193 } 194out: 195 swap_list_unlock(); 196 return entry; 197} 198 199static struct swap_info_struct * swap_info_get(swp_entry_t entry) 200{ 201 struct swap_info_struct * p; 202 unsigned long offset, type; 203 204 if (!entry.val) 205 goto out; 206 type = swp_type(entry); 207 if (type >= nr_swapfiles) 208 goto bad_nofile; 209 p = & swap_info[type]; 210 if (!(p->flags & SWP_USED)) 211 goto bad_device; 212 offset = swp_offset(entry); 213 if (offset >= p->max) 214 goto bad_offset; 215 if (!p->swap_map[offset]) 216 goto bad_free; 217 swap_list_lock(); 218 if (p->prio > swap_info[swap_list.next].prio) 219 swap_list.next = type; 220 swap_device_lock(p); 221 return p; 222 223bad_free: 224 printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val); 225 goto out; 226bad_offset: 227 printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val); 228 goto out; 229bad_device: 230 printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val); 231 goto out; 232bad_nofile: 233 printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val); 234out: 235 return NULL; 236} 237 238static void swap_info_put(struct swap_info_struct * p) 239{ 240 swap_device_unlock(p); 241 swap_list_unlock(); 242} 243 244static int swap_entry_free(struct swap_info_struct *p, unsigned long offset) 245{ 246 int count = p->swap_map[offset]; 247 248 if (count < SWAP_MAP_MAX) { 249 count--; 250 p->swap_map[offset] = count; 251 if (!count) { 252 if (offset < p->lowest_bit) 253 p->lowest_bit = offset; 254 if (offset > p->highest_bit) 255 p->highest_bit = offset; 256 nr_swap_pages++; 257 p->inuse_pages--; 258 } 259 } 260 return count; 261} 262 263/* 264 * Caller has made sure that the swapdevice corresponding to entry 265 * is still around or has not been recycled. 266 */ 267void swap_free(swp_entry_t entry) 268{ 269 struct swap_info_struct * p; 270 271 p = swap_info_get(entry); 272 if (p) { 273 swap_entry_free(p, swp_offset(entry)); 274 swap_info_put(p); 275 } 276} 277 278/* 279 * How many references to page are currently swapped out? 280 */ 281static inline int page_swapcount(struct page *page) 282{ 283 int count = 0; 284 struct swap_info_struct *p; 285 swp_entry_t entry; 286 287 entry.val = page->private; 288 p = swap_info_get(entry); 289 if (p) { 290 /* Subtract the 1 for the swap cache itself */ 291 count = p->swap_map[swp_offset(entry)] - 1; 292 swap_info_put(p); 293 } 294 return count; 295} 296 297/* 298 * We can use this swap cache entry directly 299 * if there are no other references to it. 300 */ 301int can_share_swap_page(struct page *page) 302{ 303 int count; 304 305 BUG_ON(!PageLocked(page)); 306 count = page_mapcount(page); 307 if (count <= 1 && PageSwapCache(page)) 308 count += page_swapcount(page); 309 return count == 1; 310} 311 312/* 313 * Work out if there are any other processes sharing this 314 * swap cache page. Free it if you can. Return success. 315 */ 316int remove_exclusive_swap_page(struct page *page) 317{ 318 int retval; 319 struct swap_info_struct * p; 320 swp_entry_t entry; 321 322 BUG_ON(PagePrivate(page)); 323 BUG_ON(!PageLocked(page)); 324 325 if (!PageSwapCache(page)) 326 return 0; 327 if (PageWriteback(page)) 328 return 0; 329 if (page_count(page) != 2) /* 2: us + cache */ 330 return 0; 331 332 entry.val = page->private; 333 p = swap_info_get(entry); 334 if (!p) 335 return 0; 336 337 /* Is the only swap cache user the cache itself? */ 338 retval = 0; 339 if (p->swap_map[swp_offset(entry)] == 1) { 340 /* Recheck the page count with the swapcache lock held.. */ 341 write_lock_irq(&swapper_space.tree_lock); 342 if ((page_count(page) == 2) && !PageWriteback(page)) { 343 __delete_from_swap_cache(page); 344 SetPageDirty(page); 345 retval = 1; 346 } 347 write_unlock_irq(&swapper_space.tree_lock); 348 } 349 swap_info_put(p); 350 351 if (retval) { 352 swap_free(entry); 353 page_cache_release(page); 354 } 355 356 return retval; 357} 358 359/* 360 * Free the swap entry like above, but also try to 361 * free the page cache entry if it is the last user. 362 */ 363void free_swap_and_cache(swp_entry_t entry) 364{ 365 struct swap_info_struct * p; 366 struct page *page = NULL; 367 368 p = swap_info_get(entry); 369 if (p) { 370 if (swap_entry_free(p, swp_offset(entry)) == 1) 371 page = find_trylock_page(&swapper_space, entry.val); 372 swap_info_put(p); 373 } 374 if (page) { 375 int one_user; 376 377 BUG_ON(PagePrivate(page)); 378 page_cache_get(page); 379 one_user = (page_count(page) == 2); 380 /* Only cache user (+us), or swap space full? Free it! */ 381 if (!PageWriteback(page) && (one_user || vm_swap_full())) { 382 delete_from_swap_cache(page); 383 SetPageDirty(page); 384 } 385 unlock_page(page); 386 page_cache_release(page); 387 } 388} 389 390/* 391 * Always set the resulting pte to be nowrite (the same as COW pages 392 * after one process has exited). We don't know just how many PTEs will 393 * share this swap entry, so be cautious and let do_wp_page work out 394 * what to do if a write is requested later. 395 * 396 * vma->vm_mm->page_table_lock is held. 397 */ 398static void unuse_pte(struct vm_area_struct *vma, pte_t *pte, 399 unsigned long addr, swp_entry_t entry, struct page *page) 400{ 401 inc_mm_counter(vma->vm_mm, rss); 402 get_page(page); 403 set_pte_at(vma->vm_mm, addr, pte, 404 pte_mkold(mk_pte(page, vma->vm_page_prot))); 405 page_add_anon_rmap(page, vma, addr); 406 swap_free(entry); 407 /* 408 * Move the page to the active list so it is not 409 * immediately swapped out again after swapon. 410 */ 411 activate_page(page); 412} 413 414static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, 415 unsigned long addr, unsigned long end, 416 swp_entry_t entry, struct page *page) 417{ 418 pte_t *pte; 419 pte_t swp_pte = swp_entry_to_pte(entry); 420 421 pte = pte_offset_map(pmd, addr); 422 do { 423 /* 424 * swapoff spends a _lot_ of time in this loop! 425 * Test inline before going to call unuse_pte. 426 */ 427 if (unlikely(pte_same(*pte, swp_pte))) { 428 unuse_pte(vma, pte, addr, entry, page); 429 pte_unmap(pte); 430 return 1; 431 } 432 } while (pte++, addr += PAGE_SIZE, addr != end); 433 pte_unmap(pte - 1); 434 return 0; 435} 436 437static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, 438 unsigned long addr, unsigned long end, 439 swp_entry_t entry, struct page *page) 440{ 441 pmd_t *pmd; 442 unsigned long next; 443 444 pmd = pmd_offset(pud, addr); 445 do { 446 next = pmd_addr_end(addr, end); 447 if (pmd_none_or_clear_bad(pmd)) 448 continue; 449 if (unuse_pte_range(vma, pmd, addr, next, entry, page)) 450 return 1; 451 } while (pmd++, addr = next, addr != end); 452 return 0; 453} 454 455static inline int unuse_pud_range(struct vm_area_struct *vma, pgd_t *pgd, 456 unsigned long addr, unsigned long end, 457 swp_entry_t entry, struct page *page) 458{ 459 pud_t *pud; 460 unsigned long next; 461 462 pud = pud_offset(pgd, addr); 463 do { 464 next = pud_addr_end(addr, end); 465 if (pud_none_or_clear_bad(pud)) 466 continue; 467 if (unuse_pmd_range(vma, pud, addr, next, entry, page)) 468 return 1; 469 } while (pud++, addr = next, addr != end); 470 return 0; 471} 472 473static int unuse_vma(struct vm_area_struct *vma, 474 swp_entry_t entry, struct page *page) 475{ 476 pgd_t *pgd; 477 unsigned long addr, end, next; 478 479 if (page->mapping) { 480 addr = page_address_in_vma(page, vma); 481 if (addr == -EFAULT) 482 return 0; 483 else 484 end = addr + PAGE_SIZE; 485 } else { 486 addr = vma->vm_start; 487 end = vma->vm_end; 488 } 489 490 pgd = pgd_offset(vma->vm_mm, addr); 491 do { 492 next = pgd_addr_end(addr, end); 493 if (pgd_none_or_clear_bad(pgd)) 494 continue; 495 if (unuse_pud_range(vma, pgd, addr, next, entry, page)) 496 return 1; 497 } while (pgd++, addr = next, addr != end); 498 return 0; 499} 500 501static int unuse_mm(struct mm_struct *mm, 502 swp_entry_t entry, struct page *page) 503{ 504 struct vm_area_struct *vma; 505 506 if (!down_read_trylock(&mm->mmap_sem)) { 507 /* 508 * Activate page so shrink_cache is unlikely to unmap its 509 * ptes while lock is dropped, so swapoff can make progress. 510 */ 511 activate_page(page); 512 unlock_page(page); 513 down_read(&mm->mmap_sem); 514 lock_page(page); 515 } 516 spin_lock(&mm->page_table_lock); 517 for (vma = mm->mmap; vma; vma = vma->vm_next) { 518 if (vma->anon_vma && unuse_vma(vma, entry, page)) 519 break; 520 } 521 spin_unlock(&mm->page_table_lock); 522 up_read(&mm->mmap_sem); 523 /* 524 * Currently unuse_mm cannot fail, but leave error handling 525 * at call sites for now, since we change it from time to time. 526 */ 527 return 0; 528} 529 530/* 531 * Scan swap_map from current position to next entry still in use. 532 * Recycle to start on reaching the end, returning 0 when empty. 533 */ 534static unsigned int find_next_to_unuse(struct swap_info_struct *si, 535 unsigned int prev) 536{ 537 unsigned int max = si->max; 538 unsigned int i = prev; 539 int count; 540 541 /* 542 * No need for swap_device_lock(si) here: we're just looking 543 * for whether an entry is in use, not modifying it; false 544 * hits are okay, and sys_swapoff() has already prevented new 545 * allocations from this area (while holding swap_list_lock()). 546 */ 547 for (;;) { 548 if (++i >= max) { 549 if (!prev) { 550 i = 0; 551 break; 552 } 553 /* 554 * No entries in use at top of swap_map, 555 * loop back to start and recheck there. 556 */ 557 max = prev + 1; 558 prev = 0; 559 i = 1; 560 } 561 count = si->swap_map[i]; 562 if (count && count != SWAP_MAP_BAD) 563 break; 564 } 565 return i; 566} 567 568/* 569 * We completely avoid races by reading each swap page in advance, 570 * and then search for the process using it. All the necessary 571 * page table adjustments can then be made atomically. 572 */ 573static int try_to_unuse(unsigned int type) 574{ 575 struct swap_info_struct * si = &swap_info[type]; 576 struct mm_struct *start_mm; 577 unsigned short *swap_map; 578 unsigned short swcount; 579 struct page *page; 580 swp_entry_t entry; 581 unsigned int i = 0; 582 int retval = 0; 583 int reset_overflow = 0; 584 int shmem; 585 586 /* 587 * When searching mms for an entry, a good strategy is to 588 * start at the first mm we freed the previous entry from 589 * (though actually we don't notice whether we or coincidence 590 * freed the entry). Initialize this start_mm with a hold. 591 * 592 * A simpler strategy would be to start at the last mm we 593 * freed the previous entry from; but that would take less 594 * advantage of mmlist ordering, which clusters forked mms 595 * together, child after parent. If we race with dup_mmap(), we 596 * prefer to resolve parent before child, lest we miss entries 597 * duplicated after we scanned child: using last mm would invert 598 * that. Though it's only a serious concern when an overflowed 599 * swap count is reset from SWAP_MAP_MAX, preventing a rescan. 600 */ 601 start_mm = &init_mm; 602 atomic_inc(&init_mm.mm_users); 603 604 /* 605 * Keep on scanning until all entries have gone. Usually, 606 * one pass through swap_map is enough, but not necessarily: 607 * there are races when an instance of an entry might be missed. 608 */ 609 while ((i = find_next_to_unuse(si, i)) != 0) { 610 if (signal_pending(current)) { 611 retval = -EINTR; 612 break; 613 } 614 615 /* 616 * Get a page for the entry, using the existing swap 617 * cache page if there is one. Otherwise, get a clean 618 * page and read the swap into it. 619 */ 620 swap_map = &si->swap_map[i]; 621 entry = swp_entry(type, i); 622 page = read_swap_cache_async(entry, NULL, 0); 623 if (!page) { 624 /* 625 * Either swap_duplicate() failed because entry 626 * has been freed independently, and will not be 627 * reused since sys_swapoff() already disabled 628 * allocation from here, or alloc_page() failed. 629 */ 630 if (!*swap_map) 631 continue; 632 retval = -ENOMEM; 633 break; 634 } 635 636 /* 637 * Don't hold on to start_mm if it looks like exiting. 638 */ 639 if (atomic_read(&start_mm->mm_users) == 1) { 640 mmput(start_mm); 641 start_mm = &init_mm; 642 atomic_inc(&init_mm.mm_users); 643 } 644 645 /* 646 * Wait for and lock page. When do_swap_page races with 647 * try_to_unuse, do_swap_page can handle the fault much 648 * faster than try_to_unuse can locate the entry. This 649 * apparently redundant "wait_on_page_locked" lets try_to_unuse 650 * defer to do_swap_page in such a case - in some tests, 651 * do_swap_page and try_to_unuse repeatedly compete. 652 */ 653 wait_on_page_locked(page); 654 wait_on_page_writeback(page); 655 lock_page(page); 656 wait_on_page_writeback(page); 657 658 /* 659 * Remove all references to entry. 660 * Whenever we reach init_mm, there's no address space 661 * to search, but use it as a reminder to search shmem. 662 */ 663 shmem = 0; 664 swcount = *swap_map; 665 if (swcount > 1) { 666 if (start_mm == &init_mm) 667 shmem = shmem_unuse(entry, page); 668 else 669 retval = unuse_mm(start_mm, entry, page); 670 } 671 if (*swap_map > 1) { 672 int set_start_mm = (*swap_map >= swcount); 673 struct list_head *p = &start_mm->mmlist; 674 struct mm_struct *new_start_mm = start_mm; 675 struct mm_struct *prev_mm = start_mm; 676 struct mm_struct *mm; 677 678 atomic_inc(&new_start_mm->mm_users); 679 atomic_inc(&prev_mm->mm_users); 680 spin_lock(&mmlist_lock); 681 while (*swap_map > 1 && !retval && 682 (p = p->next) != &start_mm->mmlist) { 683 mm = list_entry(p, struct mm_struct, mmlist); 684 if (atomic_inc_return(&mm->mm_users) == 1) { 685 atomic_dec(&mm->mm_users); 686 continue; 687 } 688 spin_unlock(&mmlist_lock); 689 mmput(prev_mm); 690 prev_mm = mm; 691 692 cond_resched(); 693 694 swcount = *swap_map; 695 if (swcount <= 1) 696 ; 697 else if (mm == &init_mm) { 698 set_start_mm = 1; 699 shmem = shmem_unuse(entry, page); 700 } else 701 retval = unuse_mm(mm, entry, page); 702 if (set_start_mm && *swap_map < swcount) { 703 mmput(new_start_mm); 704 atomic_inc(&mm->mm_users); 705 new_start_mm = mm; 706 set_start_mm = 0; 707 } 708 spin_lock(&mmlist_lock); 709 } 710 spin_unlock(&mmlist_lock); 711 mmput(prev_mm); 712 mmput(start_mm); 713 start_mm = new_start_mm; 714 } 715 if (retval) { 716 unlock_page(page); 717 page_cache_release(page); 718 break; 719 } 720 721 /* 722 * How could swap count reach 0x7fff when the maximum 723 * pid is 0x7fff, and there's no way to repeat a swap 724 * page within an mm (except in shmem, where it's the 725 * shared object which takes the reference count)? 726 * We believe SWAP_MAP_MAX cannot occur in Linux 2.4. 727 * 728 * If that's wrong, then we should worry more about 729 * exit_mmap() and do_munmap() cases described above: 730 * we might be resetting SWAP_MAP_MAX too early here. 731 * We know "Undead"s can happen, they're okay, so don't 732 * report them; but do report if we reset SWAP_MAP_MAX. 733 */ 734 if (*swap_map == SWAP_MAP_MAX) { 735 swap_device_lock(si); 736 *swap_map = 1; 737 swap_device_unlock(si); 738 reset_overflow = 1; 739 } 740 741 /* 742 * If a reference remains (rare), we would like to leave 743 * the page in the swap cache; but try_to_unmap could 744 * then re-duplicate the entry once we drop page lock, 745 * so we might loop indefinitely; also, that page could 746 * not be swapped out to other storage meanwhile. So: 747 * delete from cache even if there's another reference, 748 * after ensuring that the data has been saved to disk - 749 * since if the reference remains (rarer), it will be 750 * read from disk into another page. Splitting into two 751 * pages would be incorrect if swap supported "shared 752 * private" pages, but they are handled by tmpfs files. 753 * 754 * Note shmem_unuse already deleted a swappage from 755 * the swap cache, unless the move to filepage failed: 756 * in which case it left swappage in cache, lowered its 757 * swap count to pass quickly through the loops above, 758 * and now we must reincrement count to try again later. 759 */ 760 if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) { 761 struct writeback_control wbc = { 762 .sync_mode = WB_SYNC_NONE, 763 }; 764 765 swap_writepage(page, &wbc); 766 lock_page(page); 767 wait_on_page_writeback(page); 768 } 769 if (PageSwapCache(page)) { 770 if (shmem) 771 swap_duplicate(entry); 772 else 773 delete_from_swap_cache(page); 774 } 775 776 /* 777 * So we could skip searching mms once swap count went 778 * to 1, we did not mark any present ptes as dirty: must 779 * mark page dirty so shrink_list will preserve it. 780 */ 781 SetPageDirty(page); 782 unlock_page(page); 783 page_cache_release(page); 784 785 /* 786 * Make sure that we aren't completely killing 787 * interactive performance. 788 */ 789 cond_resched(); 790 } 791 792 mmput(start_mm); 793 if (reset_overflow) { 794 printk(KERN_WARNING "swapoff: cleared swap entry overflow\n"); 795 swap_overflow = 0; 796 } 797 return retval; 798} 799 800/* 801 * After a successful try_to_unuse, if no swap is now in use, we know we 802 * can empty the mmlist. swap_list_lock must be held on entry and exit. 803 * Note that mmlist_lock nests inside swap_list_lock, and an mm must be 804 * added to the mmlist just after page_duplicate - before would be racy. 805 */ 806static void drain_mmlist(void) 807{ 808 struct list_head *p, *next; 809 unsigned int i; 810 811 for (i = 0; i < nr_swapfiles; i++) 812 if (swap_info[i].inuse_pages) 813 return; 814 spin_lock(&mmlist_lock); 815 list_for_each_safe(p, next, &init_mm.mmlist) 816 list_del_init(p); 817 spin_unlock(&mmlist_lock); 818} 819 820/* 821 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which 822 * corresponds to page offset `offset'. 823 */ 824sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset) 825{ 826 struct swap_extent *se = sis->curr_swap_extent; 827 struct swap_extent *start_se = se; 828 829 for ( ; ; ) { 830 struct list_head *lh; 831 832 if (se->start_page <= offset && 833 offset < (se->start_page + se->nr_pages)) { 834 return se->start_block + (offset - se->start_page); 835 } 836 lh = se->list.next; 837 if (lh == &sis->extent_list) 838 lh = lh->next; 839 se = list_entry(lh, struct swap_extent, list); 840 sis->curr_swap_extent = se; 841 BUG_ON(se == start_se); /* It *must* be present */ 842 } 843} 844 845/* 846 * Free all of a swapdev's extent information 847 */ 848static void destroy_swap_extents(struct swap_info_struct *sis) 849{ 850 while (!list_empty(&sis->extent_list)) { 851 struct swap_extent *se; 852 853 se = list_entry(sis->extent_list.next, 854 struct swap_extent, list); 855 list_del(&se->list); 856 kfree(se); 857 } 858} 859 860/* 861 * Add a block range (and the corresponding page range) into this swapdev's 862 * extent list. The extent list is kept sorted in page order. 863 * 864 * This function rather assumes that it is called in ascending page order. 865 */ 866static int 867add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, 868 unsigned long nr_pages, sector_t start_block) 869{ 870 struct swap_extent *se; 871 struct swap_extent *new_se; 872 struct list_head *lh; 873 874 lh = sis->extent_list.prev; /* The highest page extent */ 875 if (lh != &sis->extent_list) { 876 se = list_entry(lh, struct swap_extent, list); 877 BUG_ON(se->start_page + se->nr_pages != start_page); 878 if (se->start_block + se->nr_pages == start_block) { 879 /* Merge it */ 880 se->nr_pages += nr_pages; 881 return 0; 882 } 883 } 884 885 /* 886 * No merge. Insert a new extent, preserving ordering. 887 */ 888 new_se = kmalloc(sizeof(*se), GFP_KERNEL); 889 if (new_se == NULL) 890 return -ENOMEM; 891 new_se->start_page = start_page; 892 new_se->nr_pages = nr_pages; 893 new_se->start_block = start_block; 894 895 list_add_tail(&new_se->list, &sis->extent_list); 896 return 1; 897} 898 899/* 900 * A `swap extent' is a simple thing which maps a contiguous range of pages 901 * onto a contiguous range of disk blocks. An ordered list of swap extents 902 * is built at swapon time and is then used at swap_writepage/swap_readpage 903 * time for locating where on disk a page belongs. 904 * 905 * If the swapfile is an S_ISBLK block device, a single extent is installed. 906 * This is done so that the main operating code can treat S_ISBLK and S_ISREG 907 * swap files identically. 908 * 909 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap 910 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK 911 * swapfiles are handled *identically* after swapon time. 912 * 913 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks 914 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If 915 * some stray blocks are found which do not fall within the PAGE_SIZE alignment 916 * requirements, they are simply tossed out - we will never use those blocks 917 * for swapping. 918 * 919 * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This 920 * prevents root from shooting her foot off by ftruncating an in-use swapfile, 921 * which will scribble on the fs. 922 * 923 * The amount of disk space which a single swap extent represents varies. 924 * Typically it is in the 1-4 megabyte range. So we can have hundreds of 925 * extents in the list. To avoid much list walking, we cache the previous 926 * search location in `curr_swap_extent', and start new searches from there. 927 * This is extremely effective. The average number of iterations in 928 * map_swap_page() has been measured at about 0.3 per page. - akpm. 929 */ 930static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) 931{ 932 struct inode *inode; 933 unsigned blocks_per_page; 934 unsigned long page_no; 935 unsigned blkbits; 936 sector_t probe_block; 937 sector_t last_block; 938 sector_t lowest_block = -1; 939 sector_t highest_block = 0; 940 int nr_extents = 0; 941 int ret; 942 943 inode = sis->swap_file->f_mapping->host; 944 if (S_ISBLK(inode->i_mode)) { 945 ret = add_swap_extent(sis, 0, sis->max, 0); 946 *span = sis->pages; 947 goto done; 948 } 949 950 blkbits = inode->i_blkbits; 951 blocks_per_page = PAGE_SIZE >> blkbits; 952 953 /* 954 * Map all the blocks into the extent list. This code doesn't try 955 * to be very smart. 956 */ 957 probe_block = 0; 958 page_no = 0; 959 last_block = i_size_read(inode) >> blkbits; 960 while ((probe_block + blocks_per_page) <= last_block && 961 page_no < sis->max) { 962 unsigned block_in_page; 963 sector_t first_block; 964 965 first_block = bmap(inode, probe_block); 966 if (first_block == 0) 967 goto bad_bmap; 968 969 /* 970 * It must be PAGE_SIZE aligned on-disk 971 */ 972 if (first_block & (blocks_per_page - 1)) { 973 probe_block++; 974 goto reprobe; 975 } 976 977 for (block_in_page = 1; block_in_page < blocks_per_page; 978 block_in_page++) { 979 sector_t block; 980 981 block = bmap(inode, probe_block + block_in_page); 982 if (block == 0) 983 goto bad_bmap; 984 if (block != first_block + block_in_page) { 985 /* Discontiguity */ 986 probe_block++; 987 goto reprobe; 988 } 989 } 990 991 first_block >>= (PAGE_SHIFT - blkbits); 992 if (page_no) { /* exclude the header page */ 993 if (first_block < lowest_block) 994 lowest_block = first_block; 995 if (first_block > highest_block) 996 highest_block = first_block; 997 } 998 999 /* 1000 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks 1001 */ 1002 ret = add_swap_extent(sis, page_no, 1, first_block); 1003 if (ret < 0) 1004 goto out; 1005 nr_extents += ret; 1006 page_no++; 1007 probe_block += blocks_per_page; 1008reprobe: 1009 continue; 1010 } 1011 ret = nr_extents; 1012 *span = 1 + highest_block - lowest_block; 1013 if (page_no == 0) 1014 page_no = 1; /* force Empty message */ 1015 sis->max = page_no; 1016 sis->pages = page_no - 1; 1017 sis->highest_bit = page_no - 1; 1018done: 1019 sis->curr_swap_extent = list_entry(sis->extent_list.prev, 1020 struct swap_extent, list); 1021 goto out; 1022bad_bmap: 1023 printk(KERN_ERR "swapon: swapfile has holes\n"); 1024 ret = -EINVAL; 1025out: 1026 return ret; 1027} 1028 1029#if 0 /* We don't need this yet */ 1030#include <linux/backing-dev.h> 1031int page_queue_congested(struct page *page) 1032{ 1033 struct backing_dev_info *bdi; 1034 1035 BUG_ON(!PageLocked(page)); /* It pins the swap_info_struct */ 1036 1037 if (PageSwapCache(page)) { 1038 swp_entry_t entry = { .val = page->private }; 1039 struct swap_info_struct *sis; 1040 1041 sis = get_swap_info_struct(swp_type(entry)); 1042 bdi = sis->bdev->bd_inode->i_mapping->backing_dev_info; 1043 } else 1044 bdi = page->mapping->backing_dev_info; 1045 return bdi_write_congested(bdi); 1046} 1047#endif 1048 1049asmlinkage long sys_swapoff(const char __user * specialfile) 1050{ 1051 struct swap_info_struct * p = NULL; 1052 unsigned short *swap_map; 1053 struct file *swap_file, *victim; 1054 struct address_space *mapping; 1055 struct inode *inode; 1056 char * pathname; 1057 int i, type, prev; 1058 int err; 1059 1060 if (!capable(CAP_SYS_ADMIN)) 1061 return -EPERM; 1062 1063 pathname = getname(specialfile); 1064 err = PTR_ERR(pathname); 1065 if (IS_ERR(pathname)) 1066 goto out; 1067 1068 victim = filp_open(pathname, O_RDWR|O_LARGEFILE, 0); 1069 putname(pathname); 1070 err = PTR_ERR(victim); 1071 if (IS_ERR(victim)) 1072 goto out; 1073 1074 mapping = victim->f_mapping; 1075 prev = -1; 1076 swap_list_lock(); 1077 for (type = swap_list.head; type >= 0; type = swap_info[type].next) { 1078 p = swap_info + type; 1079 if ((p->flags & SWP_ACTIVE) == SWP_ACTIVE) { 1080 if (p->swap_file->f_mapping == mapping) 1081 break; 1082 } 1083 prev = type; 1084 } 1085 if (type < 0) { 1086 err = -EINVAL; 1087 swap_list_unlock(); 1088 goto out_dput; 1089 } 1090 if (!security_vm_enough_memory(p->pages)) 1091 vm_unacct_memory(p->pages); 1092 else { 1093 err = -ENOMEM; 1094 swap_list_unlock(); 1095 goto out_dput; 1096 } 1097 if (prev < 0) { 1098 swap_list.head = p->next; 1099 } else { 1100 swap_info[prev].next = p->next; 1101 } 1102 if (type == swap_list.next) { 1103 /* just pick something that's safe... */ 1104 swap_list.next = swap_list.head; 1105 } 1106 nr_swap_pages -= p->pages; 1107 total_swap_pages -= p->pages; 1108 p->flags &= ~SWP_WRITEOK; 1109 swap_list_unlock(); 1110 current->flags |= PF_SWAPOFF; 1111 err = try_to_unuse(type); 1112 current->flags &= ~PF_SWAPOFF; 1113 1114 /* wait for any unplug function to finish */ 1115 down_write(&swap_unplug_sem); 1116 up_write(&swap_unplug_sem); 1117 1118 if (err) { 1119 /* re-insert swap space back into swap_list */ 1120 swap_list_lock(); 1121 for (prev = -1, i = swap_list.head; i >= 0; prev = i, i = swap_info[i].next) 1122 if (p->prio >= swap_info[i].prio) 1123 break; 1124 p->next = i; 1125 if (prev < 0) 1126 swap_list.head = swap_list.next = p - swap_info; 1127 else 1128 swap_info[prev].next = p - swap_info; 1129 nr_swap_pages += p->pages; 1130 total_swap_pages += p->pages; 1131 p->flags |= SWP_WRITEOK; 1132 swap_list_unlock(); 1133 goto out_dput; 1134 } 1135 destroy_swap_extents(p); 1136 down(&swapon_sem); 1137 swap_list_lock(); 1138 drain_mmlist(); 1139 swap_device_lock(p); 1140 swap_file = p->swap_file; 1141 p->swap_file = NULL; 1142 p->max = 0; 1143 swap_map = p->swap_map; 1144 p->swap_map = NULL; 1145 p->flags = 0; 1146 swap_device_unlock(p); 1147 swap_list_unlock(); 1148 up(&swapon_sem); 1149 vfree(swap_map); 1150 inode = mapping->host; 1151 if (S_ISBLK(inode->i_mode)) { 1152 struct block_device *bdev = I_BDEV(inode); 1153 set_blocksize(bdev, p->old_block_size); 1154 bd_release(bdev); 1155 } else { 1156 down(&inode->i_sem); 1157 inode->i_flags &= ~S_SWAPFILE; 1158 up(&inode->i_sem); 1159 } 1160 filp_close(swap_file, NULL); 1161 err = 0; 1162 1163out_dput: 1164 filp_close(victim, NULL); 1165out: 1166 return err; 1167} 1168 1169#ifdef CONFIG_PROC_FS 1170/* iterator */ 1171static void *swap_start(struct seq_file *swap, loff_t *pos) 1172{ 1173 struct swap_info_struct *ptr = swap_info; 1174 int i; 1175 loff_t l = *pos; 1176 1177 down(&swapon_sem); 1178 1179 for (i = 0; i < nr_swapfiles; i++, ptr++) { 1180 if (!(ptr->flags & SWP_USED) || !ptr->swap_map) 1181 continue; 1182 if (!l--) 1183 return ptr; 1184 } 1185 1186 return NULL; 1187} 1188 1189static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) 1190{ 1191 struct swap_info_struct *ptr = v; 1192 struct swap_info_struct *endptr = swap_info + nr_swapfiles; 1193 1194 for (++ptr; ptr < endptr; ptr++) { 1195 if (!(ptr->flags & SWP_USED) || !ptr->swap_map) 1196 continue; 1197 ++*pos; 1198 return ptr; 1199 } 1200 1201 return NULL; 1202} 1203 1204static void swap_stop(struct seq_file *swap, void *v) 1205{ 1206 up(&swapon_sem); 1207} 1208 1209static int swap_show(struct seq_file *swap, void *v) 1210{ 1211 struct swap_info_struct *ptr = v; 1212 struct file *file; 1213 int len; 1214 1215 if (v == swap_info) 1216 seq_puts(swap, "Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n"); 1217 1218 file = ptr->swap_file; 1219 len = seq_path(swap, file->f_vfsmnt, file->f_dentry, " \t\n\\"); 1220 seq_printf(swap, "%*s%s\t%u\t%u\t%d\n", 1221 len < 40 ? 40 - len : 1, " ", 1222 S_ISBLK(file->f_dentry->d_inode->i_mode) ? 1223 "partition" : "file\t", 1224 ptr->pages << (PAGE_SHIFT - 10), 1225 ptr->inuse_pages << (PAGE_SHIFT - 10), 1226 ptr->prio); 1227 return 0; 1228} 1229 1230static struct seq_operations swaps_op = { 1231 .start = swap_start, 1232 .next = swap_next, 1233 .stop = swap_stop, 1234 .show = swap_show 1235}; 1236 1237static int swaps_open(struct inode *inode, struct file *file) 1238{ 1239 return seq_open(file, &swaps_op); 1240} 1241 1242static struct file_operations proc_swaps_operations = { 1243 .open = swaps_open, 1244 .read = seq_read, 1245 .llseek = seq_lseek, 1246 .release = seq_release, 1247}; 1248 1249static int __init procswaps_init(void) 1250{ 1251 struct proc_dir_entry *entry; 1252 1253 entry = create_proc_entry("swaps", 0, NULL); 1254 if (entry) 1255 entry->proc_fops = &proc_swaps_operations; 1256 return 0; 1257} 1258__initcall(procswaps_init); 1259#endif /* CONFIG_PROC_FS */ 1260 1261/* 1262 * Written 01/25/92 by Simmule Turner, heavily changed by Linus. 1263 * 1264 * The swapon system call 1265 */ 1266asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags) 1267{ 1268 struct swap_info_struct * p; 1269 char *name = NULL; 1270 struct block_device *bdev = NULL; 1271 struct file *swap_file = NULL; 1272 struct address_space *mapping; 1273 unsigned int type; 1274 int i, prev; 1275 int error; 1276 static int least_priority; 1277 union swap_header *swap_header = NULL; 1278 int swap_header_version; 1279 unsigned int nr_good_pages = 0; 1280 int nr_extents = 0; 1281 sector_t span; 1282 unsigned long maxpages = 1; 1283 int swapfilesize; 1284 unsigned short *swap_map; 1285 struct page *page = NULL; 1286 struct inode *inode = NULL; 1287 int did_down = 0; 1288 1289 if (!capable(CAP_SYS_ADMIN)) 1290 return -EPERM; 1291 swap_list_lock(); 1292 p = swap_info; 1293 for (type = 0 ; type < nr_swapfiles ; type++,p++) 1294 if (!(p->flags & SWP_USED)) 1295 break; 1296 error = -EPERM; 1297 /* 1298 * Test if adding another swap device is possible. There are 1299 * two limiting factors: 1) the number of bits for the swap 1300 * type swp_entry_t definition and 2) the number of bits for 1301 * the swap type in the swap ptes as defined by the different 1302 * architectures. To honor both limitations a swap entry 1303 * with swap offset 0 and swap type ~0UL is created, encoded 1304 * to a swap pte, decoded to a swp_entry_t again and finally 1305 * the swap type part is extracted. This will mask all bits 1306 * from the initial ~0UL that can't be encoded in either the 1307 * swp_entry_t or the architecture definition of a swap pte. 1308 */ 1309 if (type > swp_type(pte_to_swp_entry(swp_entry_to_pte(swp_entry(~0UL,0))))) { 1310 swap_list_unlock(); 1311 goto out; 1312 } 1313 if (type >= nr_swapfiles) 1314 nr_swapfiles = type+1; 1315 INIT_LIST_HEAD(&p->extent_list); 1316 p->flags = SWP_USED; 1317 p->swap_file = NULL; 1318 p->old_block_size = 0; 1319 p->swap_map = NULL; 1320 p->lowest_bit = 0; 1321 p->highest_bit = 0; 1322 p->cluster_nr = 0; 1323 p->inuse_pages = 0; 1324 spin_lock_init(&p->sdev_lock); 1325 p->next = -1; 1326 if (swap_flags & SWAP_FLAG_PREFER) { 1327 p->prio = 1328 (swap_flags & SWAP_FLAG_PRIO_MASK)>>SWAP_FLAG_PRIO_SHIFT; 1329 } else { 1330 p->prio = --least_priority; 1331 } 1332 swap_list_unlock(); 1333 name = getname(specialfile); 1334 error = PTR_ERR(name); 1335 if (IS_ERR(name)) { 1336 name = NULL; 1337 goto bad_swap_2; 1338 } 1339 swap_file = filp_open(name, O_RDWR|O_LARGEFILE, 0); 1340 error = PTR_ERR(swap_file); 1341 if (IS_ERR(swap_file)) { 1342 swap_file = NULL; 1343 goto bad_swap_2; 1344 } 1345 1346 p->swap_file = swap_file; 1347 mapping = swap_file->f_mapping; 1348 inode = mapping->host; 1349 1350 error = -EBUSY; 1351 for (i = 0; i < nr_swapfiles; i++) { 1352 struct swap_info_struct *q = &swap_info[i]; 1353 1354 if (i == type || !q->swap_file) 1355 continue; 1356 if (mapping == q->swap_file->f_mapping) 1357 goto bad_swap; 1358 } 1359 1360 error = -EINVAL; 1361 if (S_ISBLK(inode->i_mode)) { 1362 bdev = I_BDEV(inode); 1363 error = bd_claim(bdev, sys_swapon); 1364 if (error < 0) { 1365 bdev = NULL; 1366 goto bad_swap; 1367 } 1368 p->old_block_size = block_size(bdev); 1369 error = set_blocksize(bdev, PAGE_SIZE); 1370 if (error < 0) 1371 goto bad_swap; 1372 p->bdev = bdev; 1373 } else if (S_ISREG(inode->i_mode)) { 1374 p->bdev = inode->i_sb->s_bdev; 1375 down(&inode->i_sem); 1376 did_down = 1; 1377 if (IS_SWAPFILE(inode)) { 1378 error = -EBUSY; 1379 goto bad_swap; 1380 } 1381 } else { 1382 goto bad_swap; 1383 } 1384 1385 swapfilesize = i_size_read(inode) >> PAGE_SHIFT; 1386 1387 /* 1388 * Read the swap header. 1389 */ 1390 if (!mapping->a_ops->readpage) { 1391 error = -EINVAL; 1392 goto bad_swap; 1393 } 1394 page = read_cache_page(mapping, 0, 1395 (filler_t *)mapping->a_ops->readpage, swap_file); 1396 if (IS_ERR(page)) { 1397 error = PTR_ERR(page); 1398 goto bad_swap; 1399 } 1400 wait_on_page_locked(page); 1401 if (!PageUptodate(page)) 1402 goto bad_swap; 1403 kmap(page); 1404 swap_header = page_address(page); 1405 1406 if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10)) 1407 swap_header_version = 1; 1408 else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10)) 1409 swap_header_version = 2; 1410 else { 1411 printk("Unable to find swap-space signature\n"); 1412 error = -EINVAL; 1413 goto bad_swap; 1414 } 1415 1416 switch (swap_header_version) { 1417 case 1: 1418 printk(KERN_ERR "version 0 swap is no longer supported. " 1419 "Use mkswap -v1 %s\n", name); 1420 error = -EINVAL; 1421 goto bad_swap; 1422 case 2: 1423 /* Check the swap header's sub-version and the size of 1424 the swap file and bad block lists */ 1425 if (swap_header->info.version != 1) { 1426 printk(KERN_WARNING 1427 "Unable to handle swap header version %d\n", 1428 swap_header->info.version); 1429 error = -EINVAL; 1430 goto bad_swap; 1431 } 1432 1433 p->lowest_bit = 1; 1434 /* 1435 * Find out how many pages are allowed for a single swap 1436 * device. There are two limiting factors: 1) the number of 1437 * bits for the swap offset in the swp_entry_t type and 1438 * 2) the number of bits in the a swap pte as defined by 1439 * the different architectures. In order to find the 1440 * largest possible bit mask a swap entry with swap type 0 1441 * and swap offset ~0UL is created, encoded to a swap pte, 1442 * decoded to a swp_entry_t again and finally the swap 1443 * offset is extracted. This will mask all the bits from 1444 * the initial ~0UL mask that can't be encoded in either 1445 * the swp_entry_t or the architecture definition of a 1446 * swap pte. 1447 */ 1448 maxpages = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0,~0UL)))) - 1; 1449 if (maxpages > swap_header->info.last_page) 1450 maxpages = swap_header->info.last_page; 1451 p->highest_bit = maxpages - 1; 1452 1453 error = -EINVAL; 1454 if (!maxpages) 1455 goto bad_swap; 1456 if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) 1457 goto bad_swap; 1458 if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) 1459 goto bad_swap; 1460 1461 /* OK, set up the swap map and apply the bad block list */ 1462 if (!(p->swap_map = vmalloc(maxpages * sizeof(short)))) { 1463 error = -ENOMEM; 1464 goto bad_swap; 1465 } 1466 1467 error = 0; 1468 memset(p->swap_map, 0, maxpages * sizeof(short)); 1469 for (i=0; i<swap_header->info.nr_badpages; i++) { 1470 int page = swap_header->info.badpages[i]; 1471 if (page <= 0 || page >= swap_header->info.last_page) 1472 error = -EINVAL; 1473 else 1474 p->swap_map[page] = SWAP_MAP_BAD; 1475 } 1476 nr_good_pages = swap_header->info.last_page - 1477 swap_header->info.nr_badpages - 1478 1 /* header page */; 1479 if (error) 1480 goto bad_swap; 1481 } 1482 1483 if (swapfilesize && maxpages > swapfilesize) { 1484 printk(KERN_WARNING 1485 "Swap area shorter than signature indicates\n"); 1486 error = -EINVAL; 1487 goto bad_swap; 1488 } 1489 if (nr_good_pages) { 1490 p->swap_map[0] = SWAP_MAP_BAD; 1491 p->max = maxpages; 1492 p->pages = nr_good_pages; 1493 nr_extents = setup_swap_extents(p, &span); 1494 if (nr_extents < 0) { 1495 error = nr_extents; 1496 goto bad_swap; 1497 } 1498 nr_good_pages = p->pages; 1499 } 1500 if (!nr_good_pages) { 1501 printk(KERN_WARNING "Empty swap-file\n"); 1502 error = -EINVAL; 1503 goto bad_swap; 1504 } 1505 1506 down(&swapon_sem); 1507 swap_list_lock(); 1508 swap_device_lock(p); 1509 p->flags = SWP_ACTIVE; 1510 nr_swap_pages += nr_good_pages; 1511 total_swap_pages += nr_good_pages; 1512 1513 printk(KERN_INFO "Adding %uk swap on %s. " 1514 "Priority:%d extents:%d across:%lluk\n", 1515 nr_good_pages<<(PAGE_SHIFT-10), name, p->prio, 1516 nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10)); 1517 1518 /* insert swap space into swap_list: */ 1519 prev = -1; 1520 for (i = swap_list.head; i >= 0; i = swap_info[i].next) { 1521 if (p->prio >= swap_info[i].prio) { 1522 break; 1523 } 1524 prev = i; 1525 } 1526 p->next = i; 1527 if (prev < 0) { 1528 swap_list.head = swap_list.next = p - swap_info; 1529 } else { 1530 swap_info[prev].next = p - swap_info; 1531 } 1532 swap_device_unlock(p); 1533 swap_list_unlock(); 1534 up(&swapon_sem); 1535 error = 0; 1536 goto out; 1537bad_swap: 1538 if (bdev) { 1539 set_blocksize(bdev, p->old_block_size); 1540 bd_release(bdev); 1541 } 1542 destroy_swap_extents(p); 1543bad_swap_2: 1544 swap_list_lock(); 1545 swap_map = p->swap_map; 1546 p->swap_file = NULL; 1547 p->swap_map = NULL; 1548 p->flags = 0; 1549 if (!(swap_flags & SWAP_FLAG_PREFER)) 1550 ++least_priority; 1551 swap_list_unlock(); 1552 vfree(swap_map); 1553 if (swap_file) 1554 filp_close(swap_file, NULL); 1555out: 1556 if (page && !IS_ERR(page)) { 1557 kunmap(page); 1558 page_cache_release(page); 1559 } 1560 if (name) 1561 putname(name); 1562 if (did_down) { 1563 if (!error) 1564 inode->i_flags |= S_SWAPFILE; 1565 up(&inode->i_sem); 1566 } 1567 return error; 1568} 1569 1570void si_swapinfo(struct sysinfo *val) 1571{ 1572 unsigned int i; 1573 unsigned long nr_to_be_unused = 0; 1574 1575 swap_list_lock(); 1576 for (i = 0; i < nr_swapfiles; i++) { 1577 if (!(swap_info[i].flags & SWP_USED) || 1578 (swap_info[i].flags & SWP_WRITEOK)) 1579 continue; 1580 nr_to_be_unused += swap_info[i].inuse_pages; 1581 } 1582 val->freeswap = nr_swap_pages + nr_to_be_unused; 1583 val->totalswap = total_swap_pages + nr_to_be_unused; 1584 swap_list_unlock(); 1585} 1586 1587/* 1588 * Verify that a swap entry is valid and increment its swap map count. 1589 * 1590 * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as 1591 * "permanent", but will be reclaimed by the next swapoff. 1592 */ 1593int swap_duplicate(swp_entry_t entry) 1594{ 1595 struct swap_info_struct * p; 1596 unsigned long offset, type; 1597 int result = 0; 1598 1599 type = swp_type(entry); 1600 if (type >= nr_swapfiles) 1601 goto bad_file; 1602 p = type + swap_info; 1603 offset = swp_offset(entry); 1604 1605 swap_device_lock(p); 1606 if (offset < p->max && p->swap_map[offset]) { 1607 if (p->swap_map[offset] < SWAP_MAP_MAX - 1) { 1608 p->swap_map[offset]++; 1609 result = 1; 1610 } else if (p->swap_map[offset] <= SWAP_MAP_MAX) { 1611 if (swap_overflow++ < 5) 1612 printk(KERN_WARNING "swap_dup: swap entry overflow\n"); 1613 p->swap_map[offset] = SWAP_MAP_MAX; 1614 result = 1; 1615 } 1616 } 1617 swap_device_unlock(p); 1618out: 1619 return result; 1620 1621bad_file: 1622 printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val); 1623 goto out; 1624} 1625 1626struct swap_info_struct * 1627get_swap_info_struct(unsigned type) 1628{ 1629 return &swap_info[type]; 1630} 1631 1632/* 1633 * swap_device_lock prevents swap_map being freed. Don't grab an extra 1634 * reference on the swaphandle, it doesn't matter if it becomes unused. 1635 */ 1636int valid_swaphandles(swp_entry_t entry, unsigned long *offset) 1637{ 1638 int ret = 0, i = 1 << page_cluster; 1639 unsigned long toff; 1640 struct swap_info_struct *swapdev = swp_type(entry) + swap_info; 1641 1642 if (!page_cluster) /* no readahead */ 1643 return 0; 1644 toff = (swp_offset(entry) >> page_cluster) << page_cluster; 1645 if (!toff) /* first page is swap header */ 1646 toff++, i--; 1647 *offset = toff; 1648 1649 swap_device_lock(swapdev); 1650 do { 1651 /* Don't read-ahead past the end of the swap area */ 1652 if (toff >= swapdev->max) 1653 break; 1654 /* Don't read in free or bad pages */ 1655 if (!swapdev->swap_map[toff]) 1656 break; 1657 if (swapdev->swap_map[toff] == SWAP_MAP_BAD) 1658 break; 1659 toff++; 1660 ret++; 1661 } while (--i); 1662 swap_device_unlock(swapdev); 1663 return ret; 1664} 1665