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

DEFINITIONS
