mm/swap.c

/* */
This source file includes following definitions.
rw_swap_page
get_swap_page
swap_duplicate
swap_free
swap_in
try_to_swap_out
sys_idle
swap_out
try_to_free_page
add_mem_queue
free_page
__get_free_page
try_to_unuse
sys_swapoff
sys_swapon
si_swapinfo
   1 /*
   2  *  linux/mm/swap.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 /*
   8  * This file should contain most things doing the swapping from/to disk.
   9  * Started 18.12.91
  10  */
  11 
  12 #include <linux/mm.h>
  13 #include <linux/sched.h>
  14 #include <linux/head.h>
  15 #include <linux/kernel.h>
  16 #include <linux/errno.h>
  17 #include <linux/string.h>
  18 #include <linux/stat.h>
  19 
  20 #include <asm/system.h> /* for cli()/sti() */
  21 #include <asm/bitops.h>
  22 
  23 #define MAX_SWAPFILES 8
  24 
  25 #define SWP_USED        1
  26 #define SWP_WRITEOK     3
  27 
  28 #define SWP_TYPE(entry) (((entry) & 0xfe) >> 1)
  29 #define SWP_OFFSET(entry) ((entry) >> PAGE_SHIFT)
  30 #define SWP_ENTRY(type,offset) (((type) << 1) | ((offset) << PAGE_SHIFT))
  31 
  32 static int nr_swapfiles = 0;
  33 static struct wait_queue * lock_queue = NULL;
  34 
  35 static struct swap_info_struct {
  36         unsigned long flags;
  37         struct inode * swap_file;
  38         unsigned int swap_device;
  39         unsigned char * swap_map;
  40         char * swap_lockmap;
  41         int lowest_bit;
  42         int highest_bit;
  43 } swap_info[MAX_SWAPFILES];
  44 
  45 extern unsigned long free_page_list;
  46 extern int shm_swap (int);
  47 
  48 /*
  49  * The following are used to make sure we don't thrash too much...
  50  * NOTE!! NR_LAST_FREE_PAGES must be a power of 2...
  51  */
  52 #define NR_LAST_FREE_PAGES 32
  53 static unsigned long last_free_pages[NR_LAST_FREE_PAGES] = {0,};
  54 
  55 #define SWAP_BITS 4096
  56 
  57 void rw_swap_page(int rw, unsigned long entry, char * buf)
     /*  */
  58 {
  59         unsigned long type, offset;
  60         struct swap_info_struct * p;
  61 
  62         type = SWP_TYPE(entry);
  63         if (type >= nr_swapfiles) {
  64                 printk("Internal error: bad swap-device\n");
  65                 return;
  66         }
  67         p = &swap_info[type];
  68         offset = SWP_OFFSET(entry);
  69         if (offset >= SWAP_BITS) {
  70                 printk("rw_swap_page: weirdness\n");
  71                 return;
  72         }
  73         if (!(p->flags & SWP_USED)) {
  74                 printk("Trying to swap to unused swap-device\n");
  75                 return;
  76         }
  77         while (set_bit(offset,p->swap_lockmap))
  78                 sleep_on(&lock_queue);
  79         if (p->swap_device) {
  80                 ll_rw_page(rw,p->swap_device,offset,buf);
  81         } else if (p->swap_file) {
  82                 unsigned int zones[4];
  83                 unsigned int block = offset << 2;
  84                 int i;
  85 
  86                 for (i = 0; i < 4; i++)
  87                         if (!(zones[i] = bmap(p->swap_file,block++))) {
  88                                 printk("rw_swap_page: bad swap file\n");
  89                                 return;
  90                         }
  91                 ll_rw_swap_file(rw,p->swap_file->i_dev, zones,4,buf);
  92         } else
  93                 printk("re_swap_page: no swap file or device\n");
  94         if (clear_bit(offset,p->swap_lockmap))
  95                 printk("rw_swap_page: lock already cleared\n");
  96         wake_up(&lock_queue);
  97 }
  98 
  99 unsigned int get_swap_page(void)
     /*  */
 100 {
 101         struct swap_info_struct * p;
 102         unsigned int offset, type;
 103 
 104         p = swap_info;
 105         for (type = 0 ; type < nr_swapfiles ; type++,p++) {
 106                 if ((p->flags & SWP_WRITEOK) != SWP_WRITEOK)
 107                         continue;
 108                 for (offset = p->lowest_bit; offset <= p->highest_bit ; offset++) {
 109                         if (p->swap_map[offset])
 110                                 continue;
 111                         p->swap_map[offset] = 1;
 112                         if (offset == p->highest_bit)
 113                                 p->highest_bit--;
 114                         p->lowest_bit = offset;
 115                         return SWP_ENTRY(type,offset);
 116                 }
 117         }
 118         return 0;
 119 }
 120 
 121 unsigned long swap_duplicate(unsigned long entry)
     /*  */
 122 {
 123         struct swap_info_struct * p;
 124         unsigned long offset, type;
 125 
 126         if (!entry)
 127                 return 0;
 128         offset = SWP_OFFSET(entry);
 129         type = SWP_TYPE(entry);
 130         if (type == SHM_SWP_TYPE)
 131                 return entry;
 132         if (type >= nr_swapfiles) {
 133                 printk("Trying to duplicate nonexistent swap-page\n");
 134                 return 0;
 135         }
 136         p = type + swap_info;
 137         if (offset >= SWAP_BITS) {
 138                 printk("swap_free: weirness\n");
 139                 return 0;
 140         }
 141         if (!p->swap_map[offset]) {
 142                 printk("swap_duplicate: trying to duplicate unused page\n");
 143                 return 0;
 144         }
 145         p->swap_map[offset]++;
 146         return entry;
 147 }
 148 
 149 void swap_free(unsigned long entry)
     /*  */
 150 {
 151         struct swap_info_struct * p;
 152         unsigned long offset, type;
 153 
 154         if (!entry)
 155                 return;
 156         type = SWP_TYPE(entry);
 157         if (type == SHM_SWP_TYPE)
 158                 return;
 159         if (type >= nr_swapfiles) {
 160                 printk("Trying to free nonexistent swap-page\n");
 161                 return;
 162         }
 163         p = & swap_info[type];
 164         offset = SWP_OFFSET(entry);
 165         if (offset >= SWAP_BITS) {
 166                 printk("swap_free: weirness\n");
 167                 return;
 168         }
 169         if (!(p->flags & SWP_USED)) {
 170                 printk("Trying to free swap from unused swap-device\n");
 171                 return;
 172         }
 173         while (set_bit(offset,p->swap_lockmap))
 174                 sleep_on(&lock_queue);
 175         if (offset < p->lowest_bit)
 176                 p->lowest_bit = offset;
 177         if (offset > p->highest_bit)
 178                 p->highest_bit = offset;
 179         if (!p->swap_map[offset])
 180                 printk("swap_free: swap-space map bad (entry %08x)\n",entry);
 181         else
 182                 p->swap_map[offset]--;
 183         if (clear_bit(offset,p->swap_lockmap))
 184                 printk("swap_free: lock already cleared\n");
 185         wake_up(&lock_queue);
 186 }
 187 
 188 void swap_in(unsigned long *table_ptr)
     /*  */
 189 {
 190         unsigned long entry;
 191         unsigned long page;
 192 
 193         entry = *table_ptr;
 194         if (PAGE_PRESENT & entry) {
 195                 printk("trying to swap in present page\n");
 196                 return;
 197         }
 198         if (!entry) {
 199                 printk("No swap page in swap_in\n");
 200                 return;
 201         }
 202         if (SWP_TYPE(entry) == SHM_SWP_TYPE) 
 203                 return shm_no_page ((unsigned long *) table_ptr);
 204         page = get_free_page(GFP_KERNEL);
 205         if (!page) {
 206                 oom(current);
 207                 page = BAD_PAGE;
 208         } else  
 209                 read_swap_page(entry, (char *) page);
 210         if (*table_ptr != entry) {
 211                 free_page(page);
 212                 return;
 213         }
 214         *table_ptr = page | (PAGE_DIRTY | PAGE_PRIVATE);
 215         swap_free(entry);
 216 }
 217 
 218 static int try_to_swap_out(unsigned long * table_ptr)
     /*  */
 219 {
 220         int i;
 221         unsigned long page;
 222         unsigned long entry;
 223 
 224         page = *table_ptr;
 225         if (!(PAGE_PRESENT & page))
 226                 return 0;
 227         if (page >= high_memory) {
 228                 printk("try_to_swap_out: bad page (%08x)\n",page);
 229                 *table_ptr = 0;
 230                 return 0;
 231         }
 232         if (mem_map[MAP_NR(page)] & MAP_PAGE_RESERVED)
 233                 return 0;
 234         if (PAGE_ACCESSED & page) {
 235                 *table_ptr &= ~PAGE_ACCESSED;
 236                 return 0;
 237         }
 238         for (i = 0; i < NR_LAST_FREE_PAGES; i++)
 239                 if (last_free_pages[i] == (page & 0xfffff000))
 240                         return 0;
 241         if (PAGE_DIRTY & page) {
 242                 page &= 0xfffff000;
 243                 if (mem_map[MAP_NR(page)] != 1)
 244                         return 0;
 245                 if (!(entry = get_swap_page()))
 246                         return 0;
 247                 *table_ptr = entry;
 248                 invalidate();
 249                 write_swap_page(entry, (char *) page);
 250                 free_page(page);
 251                 return 1;
 252         }
 253         page &= 0xfffff000;
 254         *table_ptr = 0;
 255         invalidate();
 256         free_page(page);
 257         return 1 + mem_map[MAP_NR(page)];
 258 }
 259 
 260 /*
 261  * sys_idle() does nothing much: it just searches for likely candidates for
 262  * swapping out or forgetting about. This speeds up the search when we
 263  * actually have to swap.
 264  */
 265 int sys_idle(void)
     /*  */
 266 {
 267         need_resched = 1;
 268         return 0;
 269 }
 270 
 271 /*
 272  * Go through the page tables, searching for a user page that
 273  * we can swap out.
 274  * 
 275  * We now check that the process is swappable (normally only 'init'
 276  * is un-swappable), allowing high-priority processes which cannot be
 277  * swapped out (things like user-level device drivers (Not implemented)).
 278  */
 279 static int swap_out(unsigned int priority)
     /*  */
 280 {
 281         static int swap_task = 1;
 282         static int swap_table = 0;
 283         static int swap_page = 0;
 284         int counter = NR_TASKS*8;
 285         int pg_table;
 286         struct task_struct * p;
 287 
 288         counter >>= priority;
 289 check_task:
 290         if (counter-- < 0)
 291                 return 0;
 292         if (swap_task >= NR_TASKS) {
 293                 swap_task = 1;
 294                 goto check_task;
 295         }
 296         p = task[swap_task];
 297         if (!p || !p->swappable) {
 298                 swap_task++;
 299                 goto check_task;
 300         }
 301 check_dir:
 302         if (swap_table >= 1024) {
 303                 swap_table = 0;
 304                 swap_task++;
 305                 goto check_task;
 306         }
 307         pg_table = ((unsigned long *) p->tss.cr3)[swap_table];
 308         if (pg_table >= high_memory || (mem_map[MAP_NR(pg_table)] & MAP_PAGE_RESERVED)) {
 309                 swap_table++;
 310                 goto check_dir;
 311         }
 312         if (!(PAGE_PRESENT & pg_table)) {
 313                 printk("bad page-table at pg_dir[%d]: %08x\n",
 314                         swap_table,pg_table);
 315                 ((unsigned long *) p->tss.cr3)[swap_table] = 0;
 316                 swap_table++;
 317                 goto check_dir;
 318         }
 319         pg_table &= 0xfffff000;
 320 check_table:
 321         if (swap_page >= 1024) {
 322                 swap_page = 0;
 323                 swap_table++;
 324                 goto check_dir;
 325         }
 326         switch (try_to_swap_out(swap_page + (unsigned long *) pg_table)) {
 327                 case 0: break;
 328                 case 1: p->rss--; return 1;
 329                 default: p->rss--;
 330         }
 331         swap_page++;
 332         goto check_table;
 333 }
 334 
 335 static int try_to_free_page(void)
     /*  */
 336 {
 337         int i=6;
 338 
 339         while (i--) {
 340                 if (shrink_buffers(i))
 341                         return 1;
 342                 if (shm_swap(i))
 343                         return 1;
 344                 if (swap_out(i))
 345                         return 1;
 346         }
 347         return 0;
 348 }
 349 
 350 /*
 351  * Note that this must be atomic, or bad things will happen when
 352  * pages are requested in interrupts (as malloc can do). Thus the
 353  * cli/sti's.
 354  */
 355 static inline void add_mem_queue(unsigned long addr, unsigned long * queue)
     /*  */
 356 {
 357         addr &= 0xfffff000;
 358         *(unsigned long *) addr = *queue;
 359         *queue = addr;
 360 }
 361 
 362 /*
 363  * Free_page() adds the page to the free lists. This is optimized for
 364  * fast normal cases (no error jumps taken normally).
 365  *
 366  * The way to optimize jumps for gcc-2.2.2 is to:
 367  *  - select the "normal" case and put it inside the if () { XXX }
 368  *  - no else-statements if you can avoid them
 369  *
 370  * With the above two rules, you get a straight-line execution path
 371  * for the normal case, giving better asm-code.
 372  */
 373 void free_page(unsigned long addr)
     /*  */
 374 {
 375         if (addr < high_memory) {
 376                 unsigned short * map = mem_map + MAP_NR(addr);
 377 
 378                 if (*map) {
 379                         if (!(*map & MAP_PAGE_RESERVED)) {
 380                                 unsigned long flag;
 381 
 382                                 save_flags(flag);
 383                                 cli();
 384                                 if (!--*map) {
 385                                         if (nr_secondary_pages < MAX_SECONDARY_PAGES) {
 386                                                 add_mem_queue(addr,&secondary_page_list);
 387                                                 nr_secondary_pages++;
 388                                                 restore_flags(flag);
 389                                                 return;
 390                                         }
 391                                         add_mem_queue(addr,&free_page_list);
 392                                         nr_free_pages++;
 393                                 }
 394                                 restore_flags(flag);
 395                         }
 396                         return;
 397                 }
 398                 printk("Trying to free free memory (%08x): memory probabably corrupted\n",addr);
 399                 printk("PC = %08x\n",*(((unsigned long *)&addr)-1));
 400                 return;
 401         }
 402         printk("Trying to free nonexistent page %08x\n",addr);
 403         return;
 404 }
 405 
 406 /*
 407  * This is one ugly macro, but it simplifies checking, and makes
 408  * this speed-critical place reasonably fast, especially as we have
 409  * to do things with the interrupt flag etc.
 410  *
 411  * Note that this #define is heavily optimized to give fast code
 412  * for the normal case - the if-statements are ordered so that gcc-2.2.2
 413  * will make *no* jumps for the normal code. Don't touch unless you
 414  * know what you are doing.
 415  */
 416 #define REMOVE_FROM_MEM_QUEUE(queue,nr) \
 417         cli(); \
 418         if ((result = queue) != 0) { \
 419                 if (!(result & 0xfff) && result < high_memory) { \
 420                         queue = *(unsigned long *) result; \
 421                         if (!mem_map[MAP_NR(result)]) { \
 422                                 mem_map[MAP_NR(result)] = 1; \
 423                                 nr--; \
 424 last_free_pages[index = (index + 1) & (NR_LAST_FREE_PAGES - 1)] = result; \
 425                                 restore_flags(flag); \
 426                                 return result; \
 427                         } \
 428                         printk("Free page %08x has mem_map = %d\n", \
 429                                 result,mem_map[MAP_NR(result)]); \
 430                 } else \
 431                         printk("Result = 0x%08x - memory map destroyed\n", result); \
 432                 queue = 0; \
 433                 nr = 0; \
 434         } else if (nr) { \
 435                 printk(#nr " is %d, but " #queue " is empty\n",nr); \
 436                 nr = 0; \
 437         } \
 438         restore_flags(flag)
 439 
 440 /*
 441  * Get physical address of first (actually last :-) free page, and mark it
 442  * used. If no free pages left, return 0.
 443  *
 444  * Note that this is one of the most heavily called functions in the kernel,
 445  * so it's a bit timing-critical (especially as we have to disable interrupts
 446  * in it). See the above macro which does most of the work, and which is
 447  * optimized for a fast normal path of execution.
 448  */
 449 unsigned long __get_free_page(int priority)
     /*  */
 450 {
 451         unsigned long result, flag;
 452         static unsigned long index = 0;
 453 
 454         /* this routine can be called at interrupt time via
 455            malloc.  We want to make sure that the critical
 456            sections of code have interrupts disabled. -RAB
 457            Is this code reentrant? */
 458 
 459         save_flags(flag);
 460 repeat:
 461         REMOVE_FROM_MEM_QUEUE(free_page_list,nr_free_pages);
 462         if (priority == GFP_BUFFER)
 463                 return 0;
 464         if (priority != GFP_ATOMIC)
 465                 if (try_to_free_page())
 466                         goto repeat;
 467         REMOVE_FROM_MEM_QUEUE(secondary_page_list,nr_secondary_pages);
 468         return 0;
 469 }
 470 
 471 /*
 472  * Trying to stop swapping from a file is fraught with races, so
 473  * we repeat quite a bit here when we have to pause. swapoff()
 474  * isn't exactly timing-critical, so who cares?
 475  */
 476 static int try_to_unuse(unsigned int type)
     /*  */
 477 {
 478         int nr, pgt, pg;
 479         unsigned long page, *ppage;
 480         unsigned long tmp = 0;
 481         struct task_struct *p;
 482 
 483         nr = 0;
 484 /*
 485  * When we have to sleep, we restart the whole algorithm from the same
 486  * task we stopped in. That at least rids us of all races.
 487  */
 488 repeat:
 489         for (; nr < NR_TASKS ; nr++) {
 490                 p = task[nr];
 491                 if (!p)
 492                         continue;
 493                 for (pgt = 0 ; pgt < 1024 ; pgt++) {
 494                         ppage = pgt + ((unsigned long *) p->tss.cr3);
 495                         page = *ppage;
 496                         if (!page)
 497                                 continue;
 498                         if (!(page & PAGE_PRESENT) || (page >= high_memory)) {
 499                                 printk("try_to_unuse: bad page directory (%d,%d:%08x)\n",nr,pgt,page);
 500                                 *ppage = 0;
 501                                 continue;
 502                         }
 503                         if (mem_map[MAP_NR(page)] & MAP_PAGE_RESERVED)
 504                                 continue;
 505                         ppage = (unsigned long *) (page & 0xfffff000);  
 506                         for (pg = 0 ; pg < 1024 ; pg++,ppage++) {
 507                                 page = *ppage;
 508                                 if (!page)
 509                                         continue;
 510                                 if (page & PAGE_PRESENT) {
 511                                         if (page >= high_memory) {
 512                                                 printk("try_to_unuse: bad page table (%d,%d,%d:%08x)\n",nr,pgt,pg,page);
 513                                                 *ppage = 0;
 514                                         }
 515                                         continue;
 516                                 }
 517                                 if (SWP_TYPE(page) != type)
 518                                         continue;
 519                                 if (!tmp) {
 520                                         tmp = get_free_page(GFP_KERNEL);
 521                                         if (!tmp)
 522                                                 return -ENOMEM;
 523                                         goto repeat;
 524                                 }
 525                                 read_swap_page(page, (char *) tmp);
 526                                 if (*ppage == page) {
 527                                         *ppage = tmp | (PAGE_DIRTY | PAGE_PRIVATE);
 528                                         ++p->rss;
 529                                         swap_free(page);
 530                                         tmp = 0;
 531                                 }
 532                                 goto repeat;
 533                         }
 534                 }
 535         }
 536         free_page(tmp);
 537         return 0;
 538 }
 539 
 540 int sys_swapoff(const char * specialfile)
     /*  */
 541 {
 542         struct swap_info_struct * p;
 543         struct inode * inode;
 544         unsigned int type;
 545         int i;
 546 
 547         if (!suser())
 548                 return -EPERM;
 549         i = namei(specialfile,&inode);
 550         if (i)
 551                 return i;
 552         p = swap_info;
 553         for (type = 0 ; type < nr_swapfiles ; type++,p++) {
 554                 if ((p->flags & SWP_WRITEOK) != SWP_WRITEOK)
 555                         continue;
 556                 if (p->swap_file) {
 557                         if (p->swap_file == inode)
 558                                 break;
 559                 } else {
 560                         if (!S_ISBLK(inode->i_mode))
 561                                 continue;
 562                         if (p->swap_device == inode->i_rdev)
 563                                 break;
 564                 }
 565         }
 566         iput(inode);
 567         if (type >= nr_swapfiles)
 568                 return -EINVAL;
 569         p->flags = SWP_USED;
 570         i = try_to_unuse(type);
 571         if (i) {
 572                 p->flags = SWP_WRITEOK;
 573                 return i;
 574         }
 575         iput(p->swap_file);
 576         p->swap_file = NULL;
 577         p->swap_device = 0;
 578         free_page((long) p->swap_map);
 579         p->swap_map = NULL;
 580         free_page((long) p->swap_lockmap);
 581         p->swap_lockmap = NULL;
 582         p->flags = 0;
 583         return 0;
 584 }
 585 
 586 /*
 587  * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
 588  *
 589  * The swapon system call
 590  */
 591 int sys_swapon(const char * specialfile)
     /*  */
 592 {
 593         struct swap_info_struct * p;
 594         struct inode * swap_inode;
 595         unsigned int type;
 596         char * tmp;
 597         int i,j;
 598 
 599         if (!suser())
 600                 return -EPERM;
 601         p = swap_info;
 602         for (type = 0 ; type < nr_swapfiles ; type++,p++)
 603                 if (!(p->flags & SWP_USED))
 604                         break;
 605         if (type >= MAX_SWAPFILES)
 606                 return -EPERM;
 607         if (type >= nr_swapfiles)
 608                 nr_swapfiles = type+1;
 609         p->flags = SWP_USED;
 610         p->swap_file = NULL;
 611         p->swap_device = 0;
 612         p->swap_map = NULL;
 613         p->swap_lockmap = NULL;
 614         p->lowest_bit = 0;
 615         p->highest_bit = 0;
 616         i = namei(specialfile,&swap_inode);
 617         if (i) {
 618                 p->flags = 0;
 619                 return i;
 620         }
 621         if (swap_inode->i_count != 1) {
 622                 iput(swap_inode);
 623                 p->flags = 0;
 624                 return -EBUSY;
 625         }
 626         if (S_ISBLK(swap_inode->i_mode)) {
 627                 p->swap_device = swap_inode->i_rdev;
 628                 iput(swap_inode);
 629                 if (!p->swap_device) {
 630                         p->flags = 0;
 631                         return -ENODEV;
 632                 }
 633                 for (i = 0 ; i < nr_swapfiles ; i++) {
 634                         if (i == type)
 635                                 continue;
 636                         if (p->swap_device == swap_info[i].swap_device) {
 637                                 p->swap_device = 0;
 638                                 p->flags = 0;
 639                                 return -EBUSY;
 640                         }
 641                 }
 642         } else if (S_ISREG(swap_inode->i_mode))
 643                 p->swap_file = swap_inode;
 644         else {
 645                 iput(swap_inode);
 646                 p->flags = 0;
 647                 return -EINVAL;
 648         }
 649         tmp = (char *) get_free_page(GFP_USER);
 650         p->swap_lockmap = (char *) get_free_page(GFP_USER);
 651         if (!tmp || !p->swap_lockmap) {
 652                 printk("Unable to start swapping: out of memory :-)\n");
 653                 free_page((long) tmp);
 654                 free_page((long) p->swap_lockmap);
 655                 iput(p->swap_file);
 656                 p->swap_device = 0;
 657                 p->swap_file = NULL;
 658                 p->swap_map = NULL;
 659                 p->swap_lockmap = NULL;
 660                 p->flags = 0;
 661                 return -ENOMEM;
 662         }
 663         read_swap_page(SWP_ENTRY(type,0),tmp);
 664         if (strncmp("SWAP-SPACE",tmp+4086,10)) {
 665                 printk("Unable to find swap-space signature\n");
 666                 free_page((long) tmp);
 667                 free_page((long) p->swap_lockmap);
 668                 iput(p->swap_file);
 669                 p->swap_device = 0;
 670                 p->swap_file = NULL;
 671                 p->swap_map = NULL;
 672                 p->swap_lockmap = NULL;
 673                 p->flags = 0;
 674                 return -EINVAL;
 675         }
 676         memset(tmp+4086,0,10);
 677         j = 0;
 678         p->lowest_bit = 0;
 679         p->highest_bit = 0;
 680         for (i = 1 ; i < SWAP_BITS ; i++)
 681                 if (test_bit(i,tmp)) {
 682                         if (!p->lowest_bit)
 683                                 p->lowest_bit = i;
 684                         p->highest_bit = i;
 685                         j++;
 686                 }
 687         if (!j) {
 688                 printk("Empty swap-file\n");
 689                 free_page((long) tmp);
 690                 free_page((long) p->swap_lockmap);
 691                 iput(p->swap_file);
 692                 p->swap_device = 0;
 693                 p->swap_file = NULL;
 694                 p->swap_map = NULL;
 695                 p->swap_lockmap = NULL;
 696                 p->flags = 0;
 697                 return -EINVAL;
 698         }
 699         i = SWAP_BITS;
 700         while (i--)
 701                 if (test_bit(i,tmp))
 702                         tmp[i] = 0;
 703                 else
 704                         tmp[i] = 128;
 705         tmp[0] = 128;
 706         p->swap_map = tmp;
 707         p->flags = SWP_WRITEOK;
 708         printk("Adding Swap: %dk swap-space\n",j<<2);
 709         return 0;
 710 }
 711 
 712 void si_swapinfo(struct sysinfo *val)
     /*  */
 713 {
 714         unsigned int i, j;
 715 
 716         val->freeswap = val->totalswap = 0;
 717         for (i = 0; i < nr_swapfiles; i++) {
 718                 if (!(swap_info[i].flags & SWP_USED))
 719                         continue;
 720                 for (j = 0; j < 4096; ++j)
 721                         switch (swap_info[i].swap_map[j]) {
 722                                 case 128:
 723                                         continue;
 724                                 case 0:
 725                                         ++val->freeswap;
 726                                 default:
 727                                         ++val->totalswap;
 728                         }
 729         }
 730         val->freeswap <<= PAGE_SHIFT;
 731         val->totalswap <<= PAGE_SHIFT;
 732         return;
 733 }
/* */
root/mm/swap.c

DEFINITIONS
