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