mm/swapfile.c

   1 /*
   2  *  linux/mm/swapfile.c
   3  *
   4  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
   5  *  Swap reorganised 29.12.95, Stephen Tweedie
   6  */
   7
   8 #include <linux/mm.h>
   9 #include <linux/smp.h>
  10 #include <linux/smp_lock.h>
  11 #include <linux/sched.h>
  12 #include <linux/head.h>
  13 #include <linux/kernel.h>
  14 #include <linux/kernel_stat.h>
  15 #include <linux/errno.h>
  16 #include <linux/string.h>
  17 #include <linux/stat.h>
  18 #include <linux/swap.h>
  19 #include <linux/fs.h>
  20 #include <linux/swapctl.h>
  21 #include <linux/malloc.h>
  22 #include <linux/blkdev.h> /* for blk_size */
  23 #include <linux/vmalloc.h>
  24 #include <linux/pagemap.h>
  25 #include <linux/shm.h>
  26
  27 #include <asm/bitops.h>
  28 #include <asm/pgtable.h>
  29
  30 unsigned int nr_swapfiles = 0;
  31
  32 struct swap_list_t swap_list = {-1, -1};
  33
  34 struct swap_info_struct swap_info[MAX_SWAPFILES];
  35
  36
  37 static inline int scan_swap_map(struct swap_info_struct *si)
  38 {
  39         unsigned long offset;
  40         /*
  41          * We try to cluster swap pages by allocating them
  42          * sequentially in swap.  Once we've allocated
  43          * SWAP_CLUSTER_MAX pages this way, however, we resort to
  44          * first-free allocation, starting a new cluster.  This
  45          * prevents us from scattering swap pages all over the entire
  46          * swap partition, so that we reduce overall disk seek times
  47          * between swap pages.  -- sct */
  48         if (si->cluster_nr) {
  49                 while (si->cluster_next <= si->highest_bit) {
  50                         offset = si->cluster_next++;
  51                         if (si->swap_map[offset])
  52                                 continue;
  53                         if (test_bit(offset, si->swap_lockmap))
  54                                 continue;
  55                         si->cluster_nr--;
  56                         goto got_page;
  57                 }
  58         }
  59         si->cluster_nr = SWAP_CLUSTER_MAX;
  60         for (offset = si->lowest_bit; offset <= si->highest_bit ; offset++) {
  61                 if (si->swap_map[offset])
  62                         continue;
  63                 if (test_bit(offset, si->swap_lockmap))
  64                         continue;
  65                 si->lowest_bit = offset;
  66 got_page:
  67                 si->swap_map[offset] = 1;
  68                 nr_swap_pages--;
  69                 if (offset == si->highest_bit)
  70                         si->highest_bit--;
  71                 si->cluster_next = offset;
  72                 return offset;
  73         }
  74         return 0;
  75 }
  76
  77 unsigned long get_swap_page(void)
  78 {
  79         struct swap_info_struct * p;
  80         unsigned long offset, entry;
  81         int type, wrapped = 0;
  82
  83         type = swap_list.next;
  84         if (type < 0)
  85                 return 0;
  86         if (nr_swap_pages == 0)
  87                 return 0;
  88
  89         while (1) {
  90                 p = &swap_info[type];
  91                 if ((p->flags & SWP_WRITEOK) == SWP_WRITEOK) {
  92                         offset = scan_swap_map(p);
  93                         if (offset) {
  94                                 entry = SWP_ENTRY(type,offset);
  95                                 type = swap_info[type].next;
  96                                 if (type < 0 ||
  97                                         p->prio != swap_info[type].prio)
  98                                 {
  99                                                 swap_list.next = swap_list.head;
 100                                 }
 101                                 else
 102                                 {
 103                                         swap_list.next = type;
 104                                 }
 105                                 return entry;
 106                         }
 107                 }
 108                 type = p->next;
 109                 if (!wrapped) {
 110                         if (type < 0 || p->prio != swap_info[type].prio) {
 111                                 type = swap_list.head;
 112                                 wrapped = 1;
 113                         }
 114                 } else if (type < 0) {
 115                         return 0;       /* out of swap space */
 116                 }
 117         }
 118 }
 119
 120
 121 void swap_free(unsigned long entry)
 122 {
 123         struct swap_info_struct * p;
 124         unsigned long offset, type;
 125
 126         if (!entry)
 127                 goto out;
 128
 129         type = SWP_TYPE(entry);
 130         if (type & SHM_SWP_TYPE)
 131                 goto out;
 132         if (type >= nr_swapfiles)
 133                 goto bad_nofile;
 134         p = & swap_info[type];
 135         if (!(p->flags & SWP_USED))
 136                 goto bad_device;
 137         if (p->prio > swap_info[swap_list.next].prio)
 138                 swap_list.next = swap_list.head;
 139         offset = SWP_OFFSET(entry);
 140         if (offset >= p->max)
 141                 goto bad_offset;
 142         if (offset < p->lowest_bit)
 143                 p->lowest_bit = offset;
 144         if (offset > p->highest_bit)
 145                 p->highest_bit = offset;
 146         if (!p->swap_map[offset])
 147                 goto bad_free;
 148         if (p->swap_map[offset] < SWAP_MAP_MAX) {
 149                 if (!--p->swap_map[offset])
 150                         nr_swap_pages++;
 151         }
 152 #ifdef DEBUG_SWAP
 153         printk("DebugVM: swap_free(entry %08lx, count now %d)\n",
 154                entry, p->swap_map[offset]);
 155 #endif
 156 out:
 157         return;
 158
 159 bad_nofile:
 160         printk("swap_free: Trying to free nonexistent swap-page\n");
 161         goto out;
 162 bad_device:
 163         printk("swap_free: Trying to free swap from unused swap-device\n");
 164         goto out;
 165 bad_offset:
 166         printk("swap_free: offset exceeds max\n");
 167         goto out;
 168 bad_free:
 169         printk("swap_free: swap-space map bad (entry %08lx)\n",entry);
 170         goto out;
 171 }
 172
 173 /*
 174  * The swap entry has been read in advance, and we return 1 to indicate
 175  * that the page has been used or is no longer needed.
 176  *
 177  * Always set the resulting pte to be nowrite (the same as COW pages
 178  * after one process has exited).  We don't know just how many PTEs will
 179  * share this swap entry, so be cautious and let do_wp_page work out
 180  * what to do if a write is requested later.
 181  */
 182 static inline void unuse_pte(struct vm_area_struct * vma, unsigned long address,
 183         pte_t *dir, unsigned long entry, unsigned long page)
 184 {
 185         pte_t pte = *dir;
 186
 187         if (pte_none(pte))
 188                 return;
 189         if (pte_present(pte)) {
 190                 /* If this entry is swap-cached, then page must already
 191                    hold the right address for any copies in physical
 192                    memory */
 193                 if (pte_page(pte) != page)
 194                         return;
 195                 /* We will be removing the swap cache in a moment, so... */
 196                 set_pte(dir, pte_mkdirty(pte));
 197                 return;
 198         }
 199         if (pte_val(pte) != entry)
 200                 return;
 201         set_pte(dir, pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
 202         swap_free(entry);
 203         atomic_inc(&mem_map[MAP_NR(page)].count);
 204         ++vma->vm_mm->rss;
 205 }
 206
 207 static inline void unuse_pmd(struct vm_area_struct * vma, pmd_t *dir,
 208         unsigned long address, unsigned long size, unsigned long offset,
 209         unsigned long entry, unsigned long page)
 210 {
 211         pte_t * pte;
 212         unsigned long end;
 213
 214         if (pmd_none(*dir))
 215                 return;
 216         if (pmd_bad(*dir)) {
 217                 printk("unuse_pmd: bad pmd (%08lx)\n", pmd_val(*dir));
 218                 pmd_clear(dir);
 219                 return;
 220         }
 221         pte = pte_offset(dir, address);
 222         offset += address & PMD_MASK;
 223         address &= ~PMD_MASK;
 224         end = address + size;
 225         if (end > PMD_SIZE)
 226                 end = PMD_SIZE;
 227         do {
 228                 unuse_pte(vma, offset+address-vma->vm_start, pte, entry, page);
 229                 address += PAGE_SIZE;
 230                 pte++;
 231         } while (address < end);
 232 }
 233
 234 static inline void unuse_pgd(struct vm_area_struct * vma, pgd_t *dir,
 235         unsigned long address, unsigned long size,
 236         unsigned long entry, unsigned long page)
 237 {
 238         pmd_t * pmd;
 239         unsigned long offset, end;
 240
 241         if (pgd_none(*dir))
 242                 return;
 243         if (pgd_bad(*dir)) {
 244                 printk("unuse_pgd: bad pgd (%08lx)\n", pgd_val(*dir));
 245                 pgd_clear(dir);
 246                 return;
 247         }
 248         pmd = pmd_offset(dir, address);
 249         offset = address & PGDIR_MASK;
 250         address &= ~PGDIR_MASK;
 251         end = address + size;
 252         if (end > PGDIR_SIZE)
 253                 end = PGDIR_SIZE;
 254         do {
 255                 unuse_pmd(vma, pmd, address, end - address, offset, entry,
 256                           page);
 257                 address = (address + PMD_SIZE) & PMD_MASK;
 258                 pmd++;
 259         } while (address < end);
 260 }
 261
 262 static void unuse_vma(struct vm_area_struct * vma, pgd_t *pgdir,
 263                         unsigned long entry, unsigned long page)
 264 {
 265         unsigned long start = vma->vm_start, end = vma->vm_end;
 266
 267         while (start < end) {
 268                 unuse_pgd(vma, pgdir, start, end - start, entry, page);
 269                 start = (start + PGDIR_SIZE) & PGDIR_MASK;
 270                 pgdir++;
 271         }
 272 }
 273
 274 static void unuse_process(struct mm_struct * mm, unsigned long entry,
 275                         unsigned long page)
 276 {
 277         struct vm_area_struct* vma;
 278
 279         /*
 280          * Go through process' page directory.
 281          */
 282         if (!mm || mm == &init_mm)
 283                 return;
 284         for (vma = mm->mmap; vma; vma = vma->vm_next) {
 285                 pgd_t * pgd = pgd_offset(mm, vma->vm_start);
 286                 unuse_vma(vma, pgd, entry, page);
 287         }
 288         return;
 289 }
 290
 291 /*
 292  * We completely avoid races by reading each swap page in advance,
 293  * and then search for the process using it.  All the necessary
 294  * page table adjustments can then be made atomically.
 295  */
 296 static int try_to_unuse(unsigned int type)
 297 {
 298         struct swap_info_struct * si = &swap_info[type];
 299         struct task_struct *p;
 300         unsigned long page = 0;
 301         struct page *page_map;
 302         unsigned long entry;
 303         int i;
 304
 305         while (1) {
 306                 /*
 307                  * Find a swap page in use and read it in.
 308                  */
 309                 for (i = 1 , entry = 0; i < si->max ; i++) {
 310                         if (si->swap_map[i] > 0 && si->swap_map[i] != SWAP_MAP_BAD) {
 311                                 entry = SWP_ENTRY(type, i);
 312                                 break;
 313                         }
 314                 }
 315                 if (!entry)
 316                         break;
 317
 318                 /* Get a page for the entry, using the existing swap
 319                    cache page if there is one.  Otherwise, get a clean
 320                    page and read the swap into it. */
 321                 page_map = read_swap_cache(entry);
 322                 if (!page_map)
 323                         return -ENOMEM;
 324                 page = page_address(page_map);
 325                 read_lock(&tasklist_lock);
 326                 for_each_task(p)
 327                         unuse_process(p->mm, entry, page);
 328                 read_unlock(&tasklist_lock);
 329                 shm_unuse(entry, page);
 330                 /* Now get rid of the extra reference to the temporary
 331                    page we've been using. */
 332                 if (PageSwapCache(page_map))
 333                         delete_from_swap_cache(page_map);
 334                 free_page(page);
 335                 if (si->swap_map[i] != 0) {
 336                         if (si->swap_map[i] != SWAP_MAP_MAX)
 337                                 printk("try_to_unuse: entry %08lx "
 338                                        "not in use\n", entry);
 339                         si->swap_map[i] = 0;
 340                         nr_swap_pages++;
 341                 }
 342         }
 343         return 0;
 344 }
 345
 346 asmlinkage int sys_swapoff(const char * specialfile)
 347 {
 348         struct swap_info_struct * p = NULL;
 349         struct dentry * dentry;
 350         struct file filp;
 351         int i, type, prev;
 352         int err = -EPERM;
 353
 354         lock_kernel();
 355         if (!capable(CAP_SYS_ADMIN))
 356                 goto out;
 357
 358         dentry = namei(specialfile);
 359         err = PTR_ERR(dentry);
 360         if (IS_ERR(dentry))
 361                 goto out;
 362
 363         prev = -1;
 364         for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
 365                 p = swap_info + type;
 366                 if ((p->flags & SWP_WRITEOK) == SWP_WRITEOK) {
 367                         if (p->swap_file) {
 368                                 if (p->swap_file == dentry)
 369                                   break;
 370                         } else {
 371                                 if (S_ISBLK(dentry->d_inode->i_mode)
 372                                     && (p->swap_device == dentry->d_inode->i_rdev))
 373                                   break;
 374                         }
 375                 }
 376                 prev = type;
 377         }
 378         err = -EINVAL;
 379         if (type < 0){
 380                 dput(dentry);
 381                 goto out;
 382         }
 383         if (prev < 0) {
 384                 swap_list.head = p->next;
 385         } else {
 386                 swap_info[prev].next = p->next;
 387         }
 388         if (type == swap_list.next) {
 389                 /* just pick something that's safe... */
 390                 swap_list.next = swap_list.head;
 391         }
 392         p->flags = SWP_USED;
 393         err = try_to_unuse(type);
 394         if (err) {
 395                 dput(dentry);
 396                 /* re-insert swap space back into swap_list */
 397                 for (prev = -1, i = swap_list.head; i >= 0; prev = i, i = swap_info[i].next)
 398                         if (p->prio >= swap_info[i].prio)
 399                                 break;
 400                 p->next = i;
 401                 if (prev < 0)
 402                         swap_list.head = swap_list.next = p - swap_info;
 403                 else
 404                         swap_info[prev].next = p - swap_info;
 405                 p->flags = SWP_WRITEOK;
 406                 goto out;
 407         }
 408         if(p->swap_device){
 409                 memset(&filp, 0, sizeof(filp));
 410                 filp.f_dentry = dentry;
 411                 filp.f_mode = 3; /* read write */
 412                 /* open it again to get fops */
 413                 if( !blkdev_open(dentry->d_inode, &filp) &&
 414                    filp.f_op && filp.f_op->release){
 415                         filp.f_op->release(dentry->d_inode,&filp);
 416                         filp.f_op->release(dentry->d_inode,&filp);
 417                 }
 418         }
 419         dput(dentry);
 420
 421         nr_swap_pages -= p->pages;
 422         dput(p->swap_file);
 423         p->swap_file = NULL;
 424         p->swap_device = 0;
 425         vfree(p->swap_map);
 426         p->swap_map = NULL;
 427         vfree(p->swap_lockmap);
 428         p->swap_lockmap = NULL;
 429         p->flags = 0;
 430         err = 0;
 431 out:
 432         unlock_kernel();
 433         return err;
 434 }
 435
 436 int get_swaparea_info(char *buf)
 437 {
 438         char * page = (char *) __get_free_page(GFP_KERNEL);
 439         struct swap_info_struct *ptr = swap_info;
 440         int i, j, len = 0, usedswap;
 441
 442         if (!page)
 443                 return -ENOMEM;
 444
 445         len += sprintf(buf, "Filename\t\t\tType\t\tSize\tUsed\tPriority\n");
 446         for (i = 0 ; i < nr_swapfiles ; i++, ptr++) {
 447                 if (ptr->flags & SWP_USED) {
 448                         char * path = d_path(ptr->swap_file, page, PAGE_SIZE);
 449
 450                         len += sprintf(buf + len, "%-31s ", path);
 451
 452                         if (!ptr->swap_device)
 453                                 len += sprintf(buf + len, "file\t\t");
 454                         else
 455                                 len += sprintf(buf + len, "partition\t");
 456
 457                         usedswap = 0;
 458                         for (j = 0; j < ptr->max; ++j)
 459                                 switch (ptr->swap_map[j]) {
 460                                         case SWAP_MAP_BAD:
 461                                         case 0:
 462                                                 continue;
 463                                         default:
 464                                                 usedswap++;
 465                                 }
 466                         len += sprintf(buf + len, "%d\t%d\t%d\n", ptr->pages << (PAGE_SHIFT - 10),
 467                                 usedswap << (PAGE_SHIFT - 10), ptr->prio);
 468                 }
 469         }
 470         free_page((unsigned long) page);
 471         return len;
 472 }
 473
 474 /*
 475  * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
 476  *
 477  * The swapon system call
 478  */
 479 asmlinkage int sys_swapon(const char * specialfile, int swap_flags)
 480 {
 481         struct swap_info_struct * p;
 482         struct dentry * swap_dentry;
 483         unsigned int type;
 484         int i, j, prev;
 485         int error = -EPERM;
 486         struct file filp;
 487         static int least_priority = 0;
 488         union swap_header *swap_header = 0;
 489         int swap_header_version;
 490         int lock_map_size = PAGE_SIZE;
 491         int nr_good_pages = 0;
 492         char tmp_lock_map = 0;
 493
 494         lock_kernel();
 495         if (!capable(CAP_SYS_ADMIN))
 496                 goto out;
 497         memset(&filp, 0, sizeof(filp));
 498         p = swap_info;
 499         for (type = 0 ; type < nr_swapfiles ; type++,p++)
 500                 if (!(p->flags & SWP_USED))
 501                         break;
 502         if (type >= MAX_SWAPFILES)
 503                 goto out;
 504         if (type >= nr_swapfiles)
 505                 nr_swapfiles = type+1;
 506         p->flags = SWP_USED;
 507         p->swap_file = NULL;
 508         p->swap_device = 0;
 509         p->swap_map = NULL;
 510         p->swap_lockmap = NULL;
 511         p->lowest_bit = 0;
 512         p->highest_bit = 0;
 513         p->cluster_nr = 0;
 514         p->max = 1;
 515         p->next = -1;
 516         if (swap_flags & SWAP_FLAG_PREFER) {
 517                 p->prio =
 518                   (swap_flags & SWAP_FLAG_PRIO_MASK)>>SWAP_FLAG_PRIO_SHIFT;
 519         } else {
 520                 p->prio = --least_priority;
 521         }
 522         swap_dentry = namei(specialfile);
 523         error = PTR_ERR(swap_dentry);
 524         if (IS_ERR(swap_dentry))
 525                 goto bad_swap_2;
 526
 527         p->swap_file = swap_dentry;
 528         error = -EINVAL;
 529
 530         if (S_ISBLK(swap_dentry->d_inode->i_mode)) {
 531                 p->swap_device = swap_dentry->d_inode->i_rdev;
 532                 set_blocksize(p->swap_device, PAGE_SIZE);
 533
 534                 filp.f_dentry = swap_dentry;
 535                 filp.f_mode = 3; /* read write */
 536                 error = blkdev_open(swap_dentry->d_inode, &filp);
 537                 if (error)
 538                         goto bad_swap_2;
 539                 set_blocksize(p->swap_device, PAGE_SIZE);
 540                 error = -ENODEV;
 541                 if (!p->swap_device ||
 542                     (blk_size[MAJOR(p->swap_device)] &&
 543                      !blk_size[MAJOR(p->swap_device)][MINOR(p->swap_device)]))
 544                         goto bad_swap;
 545                 error = -EBUSY;
 546                 for (i = 0 ; i < nr_swapfiles ; i++) {
 547                         if (i == type)
 548                                 continue;
 549                         if (p->swap_device == swap_info[i].swap_device)
 550                                 goto bad_swap;
 551                 }
 552         } else if (!S_ISREG(swap_dentry->d_inode->i_mode))
 553                 goto bad_swap;
 554         swap_header = (void *) __get_free_page(GFP_USER);
 555         if (!swap_header) {
 556                 printk("Unable to start swapping: out of memory :-)\n");
 557                 error = -ENOMEM;
 558                 goto bad_swap;
 559         }
 560
 561         p->swap_lockmap = &tmp_lock_map;
 562         rw_swap_page_nocache(READ, SWP_ENTRY(type,0), (char *) swap_header);
 563         p->swap_lockmap = 0;
 564
 565         if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10))
 566                 swap_header_version = 1;
 567         else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10))
 568                 swap_header_version = 2;
 569         else {
 570                 printk("Unable to find swap-space signature\n");
 571                 error = -EINVAL;
 572                 goto bad_swap;
 573         }
 574
 575         switch (swap_header_version) {
 576         case 1:
 577                 memset(((char *) swap_header)+PAGE_SIZE-10,0,10);
 578                 j = 0;
 579                 p->lowest_bit = 0;
 580                 p->highest_bit = 0;
 581                 for (i = 1 ; i < 8*PAGE_SIZE ; i++) {
 582                         if (test_bit(i,(char *) swap_header)) {
 583                                 if (!p->lowest_bit)
 584                                         p->lowest_bit = i;
 585                                 p->highest_bit = i;
 586                                 p->max = i+1;
 587                                 j++;
 588                         }
 589                 }
 590                 nr_good_pages = j;
 591                 p->swap_map = vmalloc(p->max * sizeof(short));
 592                 if (!p->swap_map) {
 593                         error = -ENOMEM;
 594                         goto bad_swap;
 595                 }
 596                 for (i = 1 ; i < p->max ; i++) {
 597                         if (test_bit(i,(char *) swap_header))
 598                                 p->swap_map[i] = 0;
 599                         else
 600                                 p->swap_map[i] = SWAP_MAP_BAD;
 601                 }
 602                 break;
 603
 604         case 2:
 605                 /* Check the swap header's sub-version and the size of
 606                    the swap file and bad block lists */
 607                 if (swap_header->info.version != 1) {
 608                         printk(KERN_WARNING
 609                                "Unable to handle swap header version %d\n",
 610                                swap_header->info.version);
 611                         error = -EINVAL;
 612                         goto bad_swap;
 613                 }
 614
 615                 p->lowest_bit  = 1;
 616                 p->highest_bit = swap_header->info.last_page - 1;
 617                 p->max         = swap_header->info.last_page;
 618
 619                 if (p->max >= 0x7fffffffL/PAGE_SIZE ||
 620                     (void *) &swap_header->info.badpages[swap_header->info.nr_badpages-1] >= (void *) swap_header->magic.magic) {
 621                         error = -EINVAL;
 622                         goto bad_swap;
 623                 }
 624
 625                 /* OK, set up the swap map and apply the bad block list */
 626                 if (!(p->swap_map = vmalloc (p->max * sizeof(short)))) {
 627                         error = -ENOMEM;
 628                         goto bad_swap;
 629                 }
 630
 631                 error = 0;
 632                 memset(p->swap_map, 0, p->max * sizeof(short));
 633                 for (i=0; i<swap_header->info.nr_badpages; i++) {
 634                         int page = swap_header->info.badpages[i];
 635                         if (page <= 0 || page >= swap_header->info.last_page)
 636                                 error = -EINVAL;
 637                         else
 638                                 p->swap_map[page] = SWAP_MAP_BAD;
 639                 }
 640                 nr_good_pages = swap_header->info.last_page - i;
 641                 lock_map_size = (p->max + 7) / 8;
 642                 if (error)
 643                         goto bad_swap;
 644         }
 645
 646         if (!nr_good_pages) {
 647                 printk(KERN_WARNING "Empty swap-file\n");
 648                 error = -EINVAL;
 649                 goto bad_swap;
 650         }
 651         p->swap_map[0] = SWAP_MAP_BAD;
 652         if (!(p->swap_lockmap = vmalloc (lock_map_size))) {
 653                 error = -ENOMEM;
 654                 goto bad_swap;
 655         }
 656         memset(p->swap_lockmap,0,lock_map_size);
 657         p->flags = SWP_WRITEOK;
 658         p->pages = nr_good_pages;
 659         nr_swap_pages += nr_good_pages;
 660         printk(KERN_INFO "Adding Swap: %dk swap-space (priority %d)\n",
 661                nr_good_pages<<(PAGE_SHIFT-10), p->prio);
 662
 663         /* insert swap space into swap_list: */
 664         prev = -1;
 665         for (i = swap_list.head; i >= 0; i = swap_info[i].next) {
 666                 if (p->prio >= swap_info[i].prio) {
 667                         break;
 668                 }
 669                 prev = i;
 670         }
 671         p->next = i;
 672         if (prev < 0) {
 673                 swap_list.head = swap_list.next = p - swap_info;
 674         } else {
 675                 swap_info[prev].next = p - swap_info;
 676         }
 677         error = 0;
 678         goto out;
 679 bad_swap:
 680         if(filp.f_op && filp.f_op->release)
 681                 filp.f_op->release(filp.f_dentry->d_inode,&filp);
 682 bad_swap_2:
 683         if (p->swap_lockmap)
 684                 vfree(p->swap_lockmap);
 685         if (p->swap_map)
 686                 vfree(p->swap_map);
 687         dput(p->swap_file);
 688         p->swap_device = 0;
 689         p->swap_file = NULL;
 690         p->swap_map = NULL;
 691         p->swap_lockmap = NULL;
 692         p->flags = 0;
 693 out:
 694         if (swap_header)
 695                 free_page((long) swap_header);
 696         unlock_kernel();
 697         return error;
 698 }
 699
 700 void si_swapinfo(struct sysinfo *val)
 701 {
 702         unsigned int i, j;
 703
 704         val->freeswap = val->totalswap = 0;
 705         for (i = 0; i < nr_swapfiles; i++) {
 706                 if ((swap_info[i].flags & SWP_WRITEOK) != SWP_WRITEOK)
 707                         continue;
 708                 for (j = 0; j < swap_info[i].max; ++j)
 709                         switch (swap_info[i].swap_map[j]) {
 710                                 case SWAP_MAP_BAD:
 711                                         continue;
 712                                 case 0:
 713                                         ++val->freeswap;
 714                                 default:
 715                                         ++val->totalswap;
 716                         }
 717         }
 718         val->freeswap <<= PAGE_SHIFT;
 719         val->totalswap <<= PAGE_SHIFT;
 720         return;
 721 }
 722