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/malloc.h>
   9 #include <linux/smp_lock.h>
  10 #include <linux/kernel_stat.h>
  11 #include <linux/swap.h>
  12 #include <linux/swapctl.h>
  13 #include <linux/blkdev.h> /* for blk_size */
  14 #include <linux/vmalloc.h>
  15 #include <linux/pagemap.h>
  16 #include <linux/shm.h>
  17
  18 #include <asm/pgtable.h>
  19
  20 unsigned int nr_swapfiles = 0;
  21
  22 struct swap_list_t swap_list = {-1, -1};
  23
  24 struct swap_info_struct swap_info[MAX_SWAPFILES];
  25
  26 #define SWAPFILE_CLUSTER 256
  27
  28 static inline int scan_swap_map(struct swap_info_struct *si)
  29 {
  30         unsigned long offset;
  31         /*
  32          * We try to cluster swap pages by allocating them
  33          * sequentially in swap.  Once we've allocated
  34          * SWAPFILE_CLUSTER pages this way, however, we resort to
  35          * first-free allocation, starting a new cluster.  This
  36          * prevents us from scattering swap pages all over the entire
  37          * swap partition, so that we reduce overall disk seek times
  38          * between swap pages.  -- sct */
  39         if (si->cluster_nr) {
  40                 while (si->cluster_next <= si->highest_bit) {
  41                         offset = si->cluster_next++;
  42                         if (si->swap_map[offset])
  43                                 continue;
  44                         si->cluster_nr--;
  45                         goto got_page;
  46                 }
  47         }
  48         si->cluster_nr = SWAPFILE_CLUSTER;
  49         for (offset = si->lowest_bit; offset <= si->highest_bit ; offset++) {
  50                 if (si->swap_map[offset])
  51                         continue;
  52                 si->lowest_bit = offset;
  53 got_page:
  54                 si->swap_map[offset] = 1;
  55                 nr_swap_pages--;
  56                 if (offset == si->highest_bit)
  57                         si->highest_bit--;
  58                 si->cluster_next = offset;
  59                 return offset;
  60         }
  61         return 0;
  62 }
  63
  64 unsigned long get_swap_page(void)
  65 {
  66         struct swap_info_struct * p;
  67         unsigned long offset, entry;
  68         int type, wrapped = 0;
  69
  70         type = swap_list.next;
  71         if (type < 0)
  72                 return 0;
  73         if (nr_swap_pages == 0)
  74                 return 0;
  75
  76         while (1) {
  77                 p = &swap_info[type];
  78                 if ((p->flags & SWP_WRITEOK) == SWP_WRITEOK) {
  79                         offset = scan_swap_map(p);
  80                         if (offset) {
  81                                 entry = SWP_ENTRY(type,offset);
  82                                 type = swap_info[type].next;
  83                                 if (type < 0 ||
  84                                         p->prio != swap_info[type].prio)
  85                                 {
  86                                                 swap_list.next = swap_list.head;
  87                                 }
  88                                 else
  89                                 {
  90                                         swap_list.next = type;
  91                                 }
  92                                 return entry;
  93                         }
  94                 }
  95                 type = p->next;
  96                 if (!wrapped) {
  97                         if (type < 0 || p->prio != swap_info[type].prio) {
  98                                 type = swap_list.head;
  99                                 wrapped = 1;
 100                         }
 101                 } else if (type < 0) {
 102                         return 0;       /* out of swap space */
 103                 }
 104         }
 105 }
 106
 107
 108 void swap_free(unsigned long entry)
 109 {
 110         struct swap_info_struct * p;
 111         unsigned long offset, type;
 112
 113         if (!entry)
 114                 goto out;
 115
 116         type = SWP_TYPE(entry);
 117         if (type & SHM_SWP_TYPE)
 118                 goto out;
 119         if (type >= nr_swapfiles)
 120                 goto bad_nofile;
 121         p = & swap_info[type];
 122         if (!(p->flags & SWP_USED))
 123                 goto bad_device;
 124         if (p->prio > swap_info[swap_list.next].prio)
 125                 swap_list.next = swap_list.head;
 126         offset = SWP_OFFSET(entry);
 127         if (offset >= p->max)
 128                 goto bad_offset;
 129         if (offset < p->lowest_bit)
 130                 p->lowest_bit = offset;
 131         if (offset > p->highest_bit)
 132                 p->highest_bit = offset;
 133         if (!p->swap_map[offset])
 134                 goto bad_free;
 135         if (p->swap_map[offset] < SWAP_MAP_MAX) {
 136                 if (!--p->swap_map[offset])
 137                         nr_swap_pages++;
 138         }
 139 #ifdef DEBUG_SWAP
 140         printk("DebugVM: swap_free(entry %08lx, count now %d)\n",
 141                entry, p->swap_map[offset]);
 142 #endif
 143 out:
 144         return;
 145
 146 bad_nofile:
 147         printk("swap_free: Trying to free nonexistent swap-page\n");
 148         goto out;
 149 bad_device:
 150         printk("swap_free: Trying to free swap from unused swap-device\n");
 151         goto out;
 152 bad_offset:
 153         printk("swap_free: offset exceeds max\n");
 154         goto out;
 155 bad_free:
 156         printk("swap_free: swap-space map bad (entry %08lx)\n",entry);
 157         goto out;
 158 }
 159
 160 /*
 161  * The swap entry has been read in advance, and we return 1 to indicate
 162  * that the page has been used or is no longer needed.
 163  *
 164  * Always set the resulting pte to be nowrite (the same as COW pages
 165  * after one process has exited).  We don't know just how many PTEs will
 166  * share this swap entry, so be cautious and let do_wp_page work out
 167  * what to do if a write is requested later.
 168  */
 169 static inline void unuse_pte(struct vm_area_struct * vma, unsigned long address,
 170         pte_t *dir, unsigned long entry, unsigned long page)
 171 {
 172         pte_t pte = *dir;
 173
 174         if (pte_none(pte))
 175                 return;
 176         if (pte_present(pte)) {
 177                 /* If this entry is swap-cached, then page must already
 178                    hold the right address for any copies in physical
 179                    memory */
 180                 if (pte_page(pte) != page)
 181                         return;
 182                 /* We will be removing the swap cache in a moment, so... */
 183                 set_pte(dir, pte_mkdirty(pte));
 184                 return;
 185         }
 186         if (pte_val(pte) != entry)
 187                 return;
 188         set_pte(dir, pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
 189         swap_free(entry);
 190         get_page(mem_map + MAP_NR(page));
 191         ++vma->vm_mm->rss;
 192 }
 193
 194 static inline void unuse_pmd(struct vm_area_struct * vma, pmd_t *dir,
 195         unsigned long address, unsigned long size, unsigned long offset,
 196         unsigned long entry, unsigned long page)
 197 {
 198         pte_t * pte;
 199         unsigned long end;
 200
 201         if (pmd_none(*dir))
 202                 return;
 203         if (pmd_bad(*dir)) {
 204                 printk("unuse_pmd: bad pmd (%08lx)\n", pmd_val(*dir));
 205                 pmd_clear(dir);
 206                 return;
 207         }
 208         pte = pte_offset(dir, address);
 209         offset += address & PMD_MASK;
 210         address &= ~PMD_MASK;
 211         end = address + size;
 212         if (end > PMD_SIZE)
 213                 end = PMD_SIZE;
 214         do {
 215                 unuse_pte(vma, offset+address-vma->vm_start, pte, entry, page);
 216                 address += PAGE_SIZE;
 217                 pte++;
 218         } while (address < end);
 219 }
 220
 221 static inline void unuse_pgd(struct vm_area_struct * vma, pgd_t *dir,
 222         unsigned long address, unsigned long size,
 223         unsigned long entry, unsigned long page)
 224 {
 225         pmd_t * pmd;
 226         unsigned long offset, end;
 227
 228         if (pgd_none(*dir))
 229                 return;
 230         if (pgd_bad(*dir)) {
 231                 printk("unuse_pgd: bad pgd (%08lx)\n", pgd_val(*dir));
 232                 pgd_clear(dir);
 233                 return;
 234         }
 235         pmd = pmd_offset(dir, address);
 236         offset = address & PGDIR_MASK;
 237         address &= ~PGDIR_MASK;
 238         end = address + size;
 239         if (end > PGDIR_SIZE)
 240                 end = PGDIR_SIZE;
 241         do {
 242                 unuse_pmd(vma, pmd, address, end - address, offset, entry,
 243                           page);
 244                 address = (address + PMD_SIZE) & PMD_MASK;
 245                 pmd++;
 246         } while (address < end);
 247 }
 248
 249 static void unuse_vma(struct vm_area_struct * vma, pgd_t *pgdir,
 250                         unsigned long entry, unsigned long page)
 251 {
 252         unsigned long start = vma->vm_start, end = vma->vm_end;
 253
 254         while (start < end) {
 255                 unuse_pgd(vma, pgdir, start, end - start, entry, page);
 256                 start = (start + PGDIR_SIZE) & PGDIR_MASK;
 257                 pgdir++;
 258         }
 259 }
 260
 261 static void unuse_process(struct mm_struct * mm, unsigned long entry,
 262                         unsigned long page)
 263 {
 264         struct vm_area_struct* vma;
 265
 266         /*
 267          * Go through process' page directory.
 268          */
 269         if (!mm)
 270                 return;
 271         for (vma = mm->mmap; vma; vma = vma->vm_next) {
 272                 pgd_t * pgd = pgd_offset(mm, vma->vm_start);
 273                 unuse_vma(vma, pgd, entry, page);
 274         }
 275         return;
 276 }
 277
 278 /*
 279  * We completely avoid races by reading each swap page in advance,
 280  * and then search for the process using it.  All the necessary
 281  * page table adjustments can then be made atomically.
 282  */
 283 static int try_to_unuse(unsigned int type)
 284 {
 285         struct swap_info_struct * si = &swap_info[type];
 286         struct task_struct *p;
 287         struct page *page_map;
 288         unsigned long entry, page;
 289         int i;
 290
 291         while (1) {
 292                 /*
 293                  * Find a swap page in use and read it in.
 294                  */
 295                 for (i = 1; i < si->max ; i++) {
 296                         if (si->swap_map[i] > 0 && si->swap_map[i] != SWAP_MAP_BAD) {
 297                                 goto found_entry;
 298                         }
 299                 }
 300                 break;
 301
 302         found_entry:
 303                 entry = SWP_ENTRY(type, i);
 304
 305                 /* Get a page for the entry, using the existing swap
 306                    cache page if there is one.  Otherwise, get a clean
 307                    page and read the swap into it. */
 308                 page_map = read_swap_cache(entry);
 309                 if (!page_map) {
 310                         /*
 311                          * Continue searching if the entry became unused.
 312                          */
 313                         if (si->swap_map[i] == 0)
 314                                 continue;
 315                         return -ENOMEM;
 316                 }
 317                 page = page_address(page_map);
 318                 read_lock(&tasklist_lock);
 319                 for_each_task(p)
 320                         unuse_process(p->mm, entry, page);
 321                 read_unlock(&tasklist_lock);
 322                 shm_unuse(entry, page);
 323                 /* Now get rid of the extra reference to the temporary
 324                    page we've been using. */
 325                 if (PageSwapCache(page_map))
 326                         delete_from_swap_cache(page_map);
 327                 __free_page(page_map);
 328                 /*
 329                  * Check for and clear any overflowed swap map counts.
 330                  */
 331                 if (si->swap_map[i] != 0) {
 332                         if (si->swap_map[i] != SWAP_MAP_MAX)
 333                                 printk(KERN_ERR
 334                                         "try_to_unuse: entry %08lx count=%d\n",
 335                                         entry, si->swap_map[i]);
 336                         si->swap_map[i] = 0;
 337                         nr_swap_pages++;
 338                 }
 339         }
 340         return 0;
 341 }
 342
 343 asmlinkage int sys_swapoff(const char * specialfile)
 344 {
 345         struct swap_info_struct * p = NULL;
 346         struct dentry * dentry;
 347         struct file filp;
 348         int i, type, prev;
 349         int err = -EPERM;
 350
 351         lock_kernel();
 352         if (!capable(CAP_SYS_ADMIN))
 353                 goto out;
 354
 355         dentry = namei(specialfile);
 356         err = PTR_ERR(dentry);
 357         if (IS_ERR(dentry))
 358                 goto out;
 359
 360         prev = -1;
 361         for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
 362                 p = swap_info + type;
 363                 if ((p->flags & SWP_WRITEOK) == SWP_WRITEOK) {
 364                         if (p->swap_file) {
 365                                 if (p->swap_file == dentry)
 366                                   break;
 367                         } else {
 368                                 if (S_ISBLK(dentry->d_inode->i_mode)
 369                                     && (p->swap_device == dentry->d_inode->i_rdev))
 370                                   break;
 371                         }
 372                 }
 373                 prev = type;
 374         }
 375         err = -EINVAL;
 376         if (type < 0)
 377                 goto out_dput;
 378
 379         if (prev < 0) {
 380                 swap_list.head = p->next;
 381         } else {
 382                 swap_info[prev].next = p->next;
 383         }
 384         if (type == swap_list.next) {
 385                 /* just pick something that's safe... */
 386                 swap_list.next = swap_list.head;
 387         }
 388         p->flags = SWP_USED;
 389         err = try_to_unuse(type);
 390         if (err) {
 391                 /* re-insert swap space back into swap_list */
 392                 for (prev = -1, i = swap_list.head; i >= 0; prev = i, i = swap_info[i].next)
 393                         if (p->prio >= swap_info[i].prio)
 394                                 break;
 395                 p->next = i;
 396                 if (prev < 0)
 397                         swap_list.head = swap_list.next = p - swap_info;
 398                 else
 399                         swap_info[prev].next = p - swap_info;
 400                 p->flags = SWP_WRITEOK;
 401                 goto out_dput;
 402         }
 403         if(p->swap_device){
 404                 memset(&filp, 0, sizeof(filp));
 405                 filp.f_dentry = dentry;
 406                 filp.f_mode = 3; /* read write */
 407                 /* open it again to get fops */
 408                 if( !blkdev_open(dentry->d_inode, &filp) &&
 409                    filp.f_op && filp.f_op->release){
 410                         filp.f_op->release(dentry->d_inode,&filp);
 411                         filp.f_op->release(dentry->d_inode,&filp);
 412                 }
 413         }
 414         dput(dentry);
 415
 416         dentry = p->swap_file;
 417         p->swap_file = NULL;
 418         nr_swap_pages -= p->pages;
 419         p->swap_device = 0;
 420         vfree(p->swap_map);
 421         p->swap_map = NULL;
 422         p->flags = 0;
 423         err = 0;
 424
 425 out_dput:
 426         dput(dentry);
 427 out:
 428         unlock_kernel();
 429         return err;
 430 }
 431
 432 int get_swaparea_info(char *buf)
 433 {
 434         char * page = (char *) __get_free_page(GFP_KERNEL);
 435         struct swap_info_struct *ptr = swap_info;
 436         int i, j, len = 0, usedswap;
 437
 438         if (!page)
 439                 return -ENOMEM;
 440
 441         len += sprintf(buf, "Filename\t\t\tType\t\tSize\tUsed\tPriority\n");
 442         for (i = 0 ; i < nr_swapfiles ; i++, ptr++) {
 443                 if (ptr->flags & SWP_USED) {
 444                         char * path = d_path(ptr->swap_file, page, PAGE_SIZE);
 445
 446                         len += sprintf(buf + len, "%-31s ", path);
 447
 448                         if (!ptr->swap_device)
 449                                 len += sprintf(buf + len, "file\t\t");
 450                         else
 451                                 len += sprintf(buf + len, "partition\t");
 452
 453                         usedswap = 0;
 454                         for (j = 0; j < ptr->max; ++j)
 455                                 switch (ptr->swap_map[j]) {
 456                                         case SWAP_MAP_BAD:
 457                                         case 0:
 458                                                 continue;
 459                                         default:
 460                                                 usedswap++;
 461                                 }
 462                         len += sprintf(buf + len, "%d\t%d\t%d\n", ptr->pages << (PAGE_SHIFT - 10),
 463                                 usedswap << (PAGE_SHIFT - 10), ptr->prio);
 464                 }
 465         }
 466         free_page((unsigned long) page);
 467         return len;
 468 }
 469
 470 int is_swap_partition(kdev_t dev) {
 471         struct swap_info_struct *ptr = swap_info;
 472         int i;
 473
 474         for (i = 0 ; i < nr_swapfiles ; i++, ptr++) {
 475                 if (ptr->flags & SWP_USED)
 476                         if (ptr->swap_device == dev)
 477                                 return 1;
 478         }
 479         return 0;
 480 }
 481
 482 /*
 483  * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
 484  *
 485  * The swapon system call
 486  */
 487 asmlinkage int sys_swapon(const char * specialfile, int swap_flags)
 488 {
 489         struct swap_info_struct * p;
 490         struct dentry * swap_dentry;
 491         unsigned int type;
 492         int i, j, prev;
 493         int error = -EPERM;
 494         struct file filp;
 495         static int least_priority = 0;
 496         union swap_header *swap_header = 0;
 497         int swap_header_version;
 498         int lock_map_size = PAGE_SIZE;
 499         int nr_good_pages = 0;
 500         unsigned long maxpages;
 501         int swapfilesize;
 502
 503         lock_kernel();
 504         if (!capable(CAP_SYS_ADMIN))
 505                 goto out;
 506         memset(&filp, 0, sizeof(filp));
 507         p = swap_info;
 508         for (type = 0 ; type < nr_swapfiles ; type++,p++)
 509                 if (!(p->flags & SWP_USED))
 510                         break;
 511         if (type >= MAX_SWAPFILES)
 512                 goto out;
 513         if (type >= nr_swapfiles)
 514                 nr_swapfiles = type+1;
 515         p->flags = SWP_USED;
 516         p->swap_file = NULL;
 517         p->swap_device = 0;
 518         p->swap_map = NULL;
 519         p->lowest_bit = 0;
 520         p->highest_bit = 0;
 521         p->cluster_nr = 0;
 522         p->max = 1;
 523         p->next = -1;
 524         if (swap_flags & SWAP_FLAG_PREFER) {
 525                 p->prio =
 526                   (swap_flags & SWAP_FLAG_PRIO_MASK)>>SWAP_FLAG_PRIO_SHIFT;
 527         } else {
 528                 p->prio = --least_priority;
 529         }
 530         swap_dentry = namei(specialfile);
 531         error = PTR_ERR(swap_dentry);
 532         if (IS_ERR(swap_dentry))
 533                 goto bad_swap_2;
 534
 535         p->swap_file = swap_dentry;
 536         error = -EINVAL;
 537
 538         if (S_ISBLK(swap_dentry->d_inode->i_mode)) {
 539                 kdev_t dev = swap_dentry->d_inode->i_rdev;
 540
 541                 p->swap_device = dev;
 542                 set_blocksize(dev, PAGE_SIZE);
 543
 544                 filp.f_dentry = swap_dentry;
 545                 filp.f_mode = 3; /* read write */
 546                 error = blkdev_open(swap_dentry->d_inode, &filp);
 547                 if (error)
 548                         goto bad_swap_2;
 549                 set_blocksize(dev, PAGE_SIZE);
 550                 error = -ENODEV;
 551                 if (!dev || (blk_size[MAJOR(dev)] &&
 552                      !blk_size[MAJOR(dev)][MINOR(dev)]))
 553                         goto bad_swap;
 554                 error = -EBUSY;
 555                 for (i = 0 ; i < nr_swapfiles ; i++) {
 556                         if (i == type)
 557                                 continue;
 558                         if (dev == swap_info[i].swap_device)
 559                                 goto bad_swap;
 560                 }
 561                 swapfilesize = 0;
 562                 if (blk_size[MAJOR(dev)])
 563                         swapfilesize = blk_size[MAJOR(dev)][MINOR(dev)]
 564                                 / (PAGE_SIZE / 1024);
 565         } else if (S_ISREG(swap_dentry->d_inode->i_mode)) {
 566                 error = -EBUSY;
 567                 for (i = 0 ; i < nr_swapfiles ; i++) {
 568                         if (i == type || !swap_info[i].swap_file)
 569                                 continue;
 570                         if (swap_dentry->d_inode == swap_info[i].swap_file->d_inode)
 571                                 goto bad_swap;
 572                 }
 573                 swapfilesize = swap_dentry->d_inode->i_size / PAGE_SIZE;
 574         } else
 575                 goto bad_swap;
 576
 577         swap_header = (void *) __get_free_page(GFP_USER);
 578         if (!swap_header) {
 579                 printk("Unable to start swapping: out of memory :-)\n");
 580                 error = -ENOMEM;
 581                 goto bad_swap;
 582         }
 583
 584         lock_page(mem_map + MAP_NR(swap_header));
 585         rw_swap_page_nolock(READ, SWP_ENTRY(type,0), (char *) swap_header, 1);
 586
 587         if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10))
 588                 swap_header_version = 1;
 589         else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10))
 590                 swap_header_version = 2;
 591         else {
 592                 printk("Unable to find swap-space signature\n");
 593                 error = -EINVAL;
 594                 goto bad_swap;
 595         }
 596
 597         switch (swap_header_version) {
 598         case 1:
 599                 memset(((char *) swap_header)+PAGE_SIZE-10,0,10);
 600                 j = 0;
 601                 p->lowest_bit = 0;
 602                 p->highest_bit = 0;
 603                 for (i = 1 ; i < 8*PAGE_SIZE ; i++) {
 604                         if (test_bit(i,(char *) swap_header)) {
 605                                 if (!p->lowest_bit)
 606                                         p->lowest_bit = i;
 607                                 p->highest_bit = i;
 608                                 p->max = i+1;
 609                                 j++;
 610                         }
 611                 }
 612                 nr_good_pages = j;
 613                 p->swap_map = vmalloc(p->max * sizeof(short));
 614                 if (!p->swap_map) {
 615                         error = -ENOMEM;
 616                         goto bad_swap;
 617                 }
 618                 for (i = 1 ; i < p->max ; i++) {
 619                         if (test_bit(i,(char *) swap_header))
 620                                 p->swap_map[i] = 0;
 621                         else
 622                                 p->swap_map[i] = SWAP_MAP_BAD;
 623                 }
 624                 break;
 625
 626         case 2:
 627                 /* Check the swap header's sub-version and the size of
 628                    the swap file and bad block lists */
 629                 if (swap_header->info.version != 1) {
 630                         printk(KERN_WARNING
 631                                "Unable to handle swap header version %d\n",
 632                                swap_header->info.version);
 633                         error = -EINVAL;
 634                         goto bad_swap;
 635                 }
 636
 637                 p->lowest_bit  = 1;
 638                 p->highest_bit = swap_header->info.last_page - 1;
 639                 p->max         = swap_header->info.last_page;
 640
 641                 maxpages = SWP_OFFSET(SWP_ENTRY(0,~0UL));
 642                 if (p->max >= maxpages)
 643                         p->max = maxpages-1;
 644
 645                 error = -EINVAL;
 646                 if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
 647                         goto bad_swap;
 648
 649                 /* OK, set up the swap map and apply the bad block list */
 650                 if (!(p->swap_map = vmalloc (p->max * sizeof(short)))) {
 651                         error = -ENOMEM;
 652                         goto bad_swap;
 653                 }
 654
 655                 error = 0;
 656                 memset(p->swap_map, 0, p->max * sizeof(short));
 657                 for (i=0; i<swap_header->info.nr_badpages; i++) {
 658                         int page = swap_header->info.badpages[i];
 659                         if (page <= 0 || page >= swap_header->info.last_page)
 660                                 error = -EINVAL;
 661                         else
 662                                 p->swap_map[page] = SWAP_MAP_BAD;
 663                 }
 664                 nr_good_pages = swap_header->info.last_page -
 665                                 swap_header->info.nr_badpages -
 666                                 1 /* header page */;
 667                 lock_map_size = (p->max + 7) / 8;
 668                 if (error)
 669                         goto bad_swap;
 670         }
 671
 672         if (swapfilesize && p->max > swapfilesize) {
 673                 printk(KERN_WARNING
 674                        "Swap area shorter than signature indicates\n");
 675                 error = -EINVAL;
 676                 goto bad_swap;
 677         }
 678         if (!nr_good_pages) {
 679                 printk(KERN_WARNING "Empty swap-file\n");
 680                 error = -EINVAL;
 681                 goto bad_swap;
 682         }
 683         p->swap_map[0] = SWAP_MAP_BAD;
 684         p->flags = SWP_WRITEOK;
 685         p->pages = nr_good_pages;
 686         nr_swap_pages += nr_good_pages;
 687         printk(KERN_INFO "Adding Swap: %dk swap-space (priority %d)\n",
 688                nr_good_pages<<(PAGE_SHIFT-10), p->prio);
 689
 690         /* insert swap space into swap_list: */
 691         prev = -1;
 692         for (i = swap_list.head; i >= 0; i = swap_info[i].next) {
 693                 if (p->prio >= swap_info[i].prio) {
 694                         break;
 695                 }
 696                 prev = i;
 697         }
 698         p->next = i;
 699         if (prev < 0) {
 700                 swap_list.head = swap_list.next = p - swap_info;
 701         } else {
 702                 swap_info[prev].next = p - swap_info;
 703         }
 704         error = 0;
 705         goto out;
 706 bad_swap:
 707         if(filp.f_op && filp.f_op->release)
 708                 filp.f_op->release(filp.f_dentry->d_inode,&filp);
 709 bad_swap_2:
 710         if (p->swap_map)
 711                 vfree(p->swap_map);
 712         dput(p->swap_file);
 713         p->swap_device = 0;
 714         p->swap_file = NULL;
 715         p->swap_map = NULL;
 716         p->flags = 0;
 717         if (!(swap_flags & SWAP_FLAG_PREFER))
 718                 ++least_priority;
 719 out:
 720         if (swap_header)
 721                 free_page((long) swap_header);
 722         unlock_kernel();
 723         return error;
 724 }
 725
 726 void si_swapinfo(struct sysinfo *val)
 727 {
 728         unsigned int i, j;
 729
 730         val->freeswap = val->totalswap = 0;
 731         for (i = 0; i < nr_swapfiles; i++) {
 732                 if ((swap_info[i].flags & SWP_WRITEOK) != SWP_WRITEOK)
 733                         continue;
 734                 for (j = 0; j < swap_info[i].max; ++j)
 735                         switch (swap_info[i].swap_map[j]) {
 736                                 case SWAP_MAP_BAD:
 737                                         continue;
 738                                 case 0:
 739                                         ++val->freeswap;
 740                                 default:
 741                                         ++val->totalswap;
 742                         }
 743         }
 744         val->freeswap <<= PAGE_SHIFT;
 745         val->totalswap <<= PAGE_SHIFT;
 746         return;
 747 }