mm/swap.c

/* */
This source file includes following definitions.
bitop
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 #include <asm/system.h> /* for cli()/sti() */
  20 
  21 #define MAX_SWAPFILES 8
  22 
  23 #define SWP_USED        1
  24 #define SWP_WRITEOK     3
  25 
  26 #define SWP_TYPE(entry) (((entry) & 0xffe) >> 1)
  27 #define SWP_OFFSET(entry) ((entry) >> PAGE_SHIFT)
  28 #define SWP_ENTRY(type,offset) (((type) << 1) | ((offset) << PAGE_SHIFT))
  29 
  30 static int nr_swapfiles = 0;
  31 static struct wait_queue * lock_queue = NULL;
  32 
  33 static struct swap_info_struct {
  34         unsigned long flags;
  35         struct inode * swap_file;
  36         unsigned int swap_device;
  37         unsigned char * swap_map;
  38         char * swap_lockmap;
  39         int lowest_bit;
  40         int highest_bit;
  41 } swap_info[MAX_SWAPFILES];
  42 
  43 extern unsigned long free_page_list;
  44 
  45 /*
  46  * The following are used to make sure we don't thrash too much...
  47  * NOTE!! NR_LAST_FREE_PAGES must be a power of 2...
  48  */
  49 #define NR_LAST_FREE_PAGES 32
  50 static unsigned long last_free_pages[NR_LAST_FREE_PAGES] = {0,};
  51 
  52 #define SWAP_BITS 4096
  53 
  54 #define bitop(name,op) \
  55 static inline int name(char * addr,unsigned int nr) \
  56 { \
  57 int __res; \
  58 __asm__ __volatile__("bt" op " %1,%2; adcl $0,%0" \
  59 :"=g" (__res) \
  60 :"r" (nr),"m" (*(addr)),"0" (0)); \
  61 return __res; \
  62 }
  63 
  64 bitop(bit,"")
     /*  */
  65 bitop(setbit,"s")
  66 bitop(clrbit,"r")
  67 
  68 void rw_swap_page(int rw, unsigned long entry, char * buf)
  69 {
  70         unsigned long type, offset;
  71         struct swap_info_struct * p;
  72 
  73         type = SWP_TYPE(entry);
  74         if (type >= nr_swapfiles) {
  75                 printk("Internal error: bad swap-device\n");
  76                 return;
  77         }
  78         p = &swap_info[type];
  79         offset = SWP_OFFSET(entry);
  80         if (offset >= SWAP_BITS) {
  81                 printk("rw_swap_page: weirdness\n");
  82                 return;
  83         }
  84         if (!(p->flags & SWP_USED)) {
  85                 printk("Trying to swap to unused swap-device\n");
  86                 return;
  87         }
  88         while (setbit(p->swap_lockmap,offset))
  89                 sleep_on(&lock_queue);
  90         if (p->swap_device) {
  91                 ll_rw_page(rw,p->swap_device,offset,buf);
  92         } else if (p->swap_file) {
  93                 unsigned int zones[4];
  94                 unsigned int block = offset << 2;
  95                 int i;
  96 
  97                 for (i = 0; i < 4; i++)
  98                         if (!(zones[i] = bmap(p->swap_file,block++))) {
  99                                 printk("rw_swap_page: bad swap file\n");
 100                                 return;
 101                         }
 102                 ll_rw_swap_file(rw,p->swap_file->i_dev, zones,4,buf);
 103         } else
 104                 printk("re_swap_page: no swap file or device\n");
 105         if (!clrbit(p->swap_lockmap,offset))
 106                 printk("rw_swap_page: lock already cleared\n");
 107         wake_up(&lock_queue);
 108 }
 109 
 110 static unsigned int get_swap_page(void)
     /*  */
 111 {
 112         struct swap_info_struct * p;
 113         unsigned int offset, type;
 114 
 115         p = swap_info;
 116         for (type = 0 ; type < nr_swapfiles ; type++,p++) {
 117                 if ((p->flags & SWP_WRITEOK) != SWP_WRITEOK)
 118                         continue;
 119                 for (offset = p->lowest_bit; offset <= p->highest_bit ; offset++) {
 120                         if (p->swap_map[offset])
 121                                 continue;
 122                         p->swap_map[offset] = 1;
 123                         if (offset == p->highest_bit)
 124                                 p->highest_bit--;
 125                         p->lowest_bit = offset;
 126                         return SWP_ENTRY(type,offset);
 127                 }
 128         }
 129         return 0;
 130 }
 131 
 132 unsigned long swap_duplicate(unsigned long entry)
     /*  */
 133 {
 134         struct swap_info_struct * p;
 135         unsigned long offset, type;
 136 
 137         if (!entry)
 138                 return 0;
 139         offset = SWP_OFFSET(entry);
 140         type = SWP_TYPE(entry);
 141         if (type >= nr_swapfiles) {
 142                 printk("Trying to duplicate nonexistent swap-page\n");
 143                 return 0;
 144         }
 145         p = type + swap_info;
 146         if (offset >= SWAP_BITS) {
 147                 printk("swap_free: weirness\n");
 148                 return 0;
 149         }
 150         if (!p->swap_map[offset]) {
 151                 printk("swap_duplicate: trying to duplicate unused page\n");
 152                 return 0;
 153         }
 154         p->swap_map[offset]++;
 155         return entry;
 156 }
 157 
 158 void swap_free(unsigned long entry)
     /*  */
 159 {
 160         struct swap_info_struct * p;
 161         unsigned long offset, type;
 162 
 163         if (!entry)
 164                 return;
 165         type = SWP_TYPE(entry);
 166         if (type >= nr_swapfiles) {
 167                 printk("Trying to free nonexistent swap-page\n");
 168                 return;
 169         }
 170         p = & swap_info[type];
 171         offset = SWP_OFFSET(entry);
 172         if (offset >= SWAP_BITS) {
 173                 printk("swap_free: weirness\n");
 174                 return;
 175         }
 176         if (!(p->flags & SWP_USED)) {
 177                 printk("Trying to free swap from unused swap-device\n");
 178                 return;
 179         }
 180         while (setbit(p->swap_lockmap,offset))
 181                 sleep_on(&lock_queue);
 182         if (offset < p->lowest_bit)
 183                 p->lowest_bit = offset;
 184         if (offset > p->highest_bit)
 185                 p->highest_bit = offset;
 186         if (!p->swap_map[offset])
 187                 printk("swap_free: swap-space map bad (entry %08x)\n",entry);
 188         else
 189                 p->swap_map[offset]--;
 190         if (!clrbit(p->swap_lockmap,offset))
 191                 printk("swap_free: lock already cleared\n");
 192         wake_up(&lock_queue);
 193 }
 194 
 195 void swap_in(unsigned long *table_ptr)
     /*  */
 196 {
 197         unsigned long entry;
 198         unsigned long page;
 199 
 200         entry = *table_ptr;
 201         if (PAGE_PRESENT & entry) {
 202                 printk("trying to swap in present page\n");
 203                 return;
 204         }
 205         if (!entry) {
 206                 printk("No swap page in swap_in\n");
 207                 return;
 208         }
 209         page = get_free_page(GFP_KERNEL);
 210         if (!page) {
 211                 oom(current);
 212                 page = BAD_PAGE;
 213         } else  
 214                 read_swap_page(entry, (char *) page);
 215         if (*table_ptr != entry) {
 216                 free_page(page);
 217                 return;
 218         }
 219         *table_ptr = page | (PAGE_DIRTY | PAGE_PRIVATE);
 220         swap_free(entry);
 221 }
 222 
 223 static int try_to_swap_out(unsigned long * table_ptr)
     /*  */
 224 {
 225         int i;
 226         unsigned long page;
 227         unsigned long entry;
 228 
 229         page = *table_ptr;
 230         if (!(PAGE_PRESENT & page))
 231                 return 0;
 232         if (page >= high_memory) {
 233                 printk("try_to_swap_out: bad page (%08x)\n",page);
 234                 *table_ptr = 0;
 235                 return 0;
 236         }
 237         if (mem_map[MAP_NR(page)] & MAP_PAGE_RESERVED)
 238                 return 0;
 239         if (PAGE_ACCESSED & page) {
 240                 *table_ptr &= ~PAGE_ACCESSED;
 241                 return 0;
 242         }
 243         for (i = 0; i < NR_LAST_FREE_PAGES; i++)
 244                 if (last_free_pages[i] == (page & 0xfffff000))
 245                         return 0;
 246         if (PAGE_DIRTY & page) {
 247                 page &= 0xfffff000;
 248                 if (mem_map[MAP_NR(page)] != 1)
 249                         return 0;
 250                 if (!(entry = get_swap_page()))
 251                         return 0;
 252                 *table_ptr = entry;
 253                 invalidate();
 254                 write_swap_page(entry, (char *) page);
 255                 free_page(page);
 256                 return 1;
 257         }
 258         page &= 0xfffff000;
 259         *table_ptr = 0;
 260         invalidate();
 261         free_page(page);
 262         return 1 + mem_map[MAP_NR(page)];
 263 }
 264 
 265 /*
 266  * sys_idle() does nothing much: it just searches for likely candidates for
 267  * swapping out or forgetting about. This speeds up the search when we
 268  * actually have to swap.
 269  */
 270 int sys_idle(void)
     /*  */
 271 {
 272         need_resched = 1;
 273         return 0;
 274 }
 275 
 276 /*
 277  * Go through the page tables, searching for a user page that
 278  * we can swap out.
 279  * 
 280  * We now check that the process is swappable (normally only 'init'
 281  * is un-swappable), allowing high-priority processes which cannot be
 282  * swapped out (things like user-level device drivers (Not implemented)).
 283  */
 284 static int swap_out(unsigned int priority)
     /*  */
 285 {
 286         static int swap_task = 1;
 287         static int swap_table = 0;
 288         static int swap_page = 0;
 289         int counter = NR_TASKS*8;
 290         int pg_table;
 291         struct task_struct * p;
 292 
 293         counter >>= priority;
 294 check_task:
 295         if (counter-- < 0)
 296                 return 0;
 297         if (swap_task >= NR_TASKS) {
 298                 swap_task = 1;
 299                 goto check_task;
 300         }
 301         p = task[swap_task];
 302         if (!p || !p->swappable) {
 303                 swap_task++;
 304                 goto check_task;
 305         }
 306 check_dir:
 307         if (swap_table >= 1024) {
 308                 swap_table = 0;
 309                 swap_task++;
 310                 goto check_task;
 311         }
 312         pg_table = ((unsigned long *) p->tss.cr3)[swap_table];
 313         if (pg_table >= high_memory || (mem_map[MAP_NR(pg_table)] & MAP_PAGE_RESERVED)) {
 314                 swap_table++;
 315                 goto check_dir;
 316         }
 317         if (!(PAGE_PRESENT & pg_table)) {
 318                 printk("bad page-table at pg_dir[%d]: %08x\n",
 319                         swap_table,pg_table);
 320                 ((unsigned long *) p->tss.cr3)[swap_table] = 0;
 321                 swap_table++;
 322                 goto check_dir;
 323         }
 324         pg_table &= 0xfffff000;
 325 check_table:
 326         if (swap_page >= 1024) {
 327                 swap_page = 0;
 328                 swap_table++;
 329                 goto check_dir;
 330         }
 331         switch (try_to_swap_out(swap_page + (unsigned long *) pg_table)) {
 332                 case 0: break;
 333                 case 1: p->rss--; return 1;
 334                 default: p->rss--;
 335         }
 336         swap_page++;
 337         goto check_table;
 338 }
 339 
 340 static int try_to_free_page(void)
     /*  */
 341 {
 342         int i=6;
 343 
 344         while (i--) {
 345                 if (shrink_buffers(i))
 346                         return 1;
 347                 if (swap_out(i))
 348                         return 1;
 349         }
 350         return 0;
 351 }
 352 
 353 /*
 354  * Note that this must be atomic, or bad things will happen when
 355  * pages are requested in interrupts (as malloc can do). Thus the
 356  * cli/sti's.
 357  */
 358 static inline void add_mem_queue(unsigned long addr, unsigned long * queue)
     /*  */
 359 {
 360         addr &= 0xfffff000;
 361         *(unsigned long *) addr = *queue;
 362         *queue = addr;
 363 }
 364 
 365 /*
 366  * Free_page() adds the page to the free lists. This is optimized for
 367  * fast normal cases (no error jumps taken normally).
 368  *
 369  * The way to optimize jumps for gcc-2.2.2 is to:
 370  *  - select the "normal" case and put it inside the if () { XXX }
 371  *  - no else-statements if you can avoid them
 372  *
 373  * With the above two rules, you get a straight-line execution path
 374  * for the normal case, giving better asm-code.
 375  */
 376 void free_page(unsigned long addr)
     /*  */
 377 {
 378         if (addr < high_memory) {
 379                 unsigned short * map = mem_map + MAP_NR(addr);
 380 
 381                 if (*map) {
 382                         if (!(*map & MAP_PAGE_RESERVED)) {
 383                                 unsigned long flag;
 384 
 385                                 save_flags(flag);
 386                                 cli();
 387                                 if (!--*map) {
 388                                         if (nr_secondary_pages < MAX_SECONDARY_PAGES) {
 389                                                 add_mem_queue(addr,&secondary_page_list);
 390                                                 nr_secondary_pages++;
 391                                                 restore_flags(flag);
 392                                                 return;
 393                                         }
 394                                         add_mem_queue(addr,&free_page_list);
 395                                         nr_free_pages++;
 396                                 }
 397                                 restore_flags(flag);
 398                         }
 399                         return;
 400                 }
 401                 printk("Trying to free free memory (%08x): memory probabably corrupted\n",addr);
 402                 return;
 403         }
 404         printk("Trying to free nonexistent page %08x\n",addr);
 405         return;
 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                                 printk("try_to_unuse: bad page directory (%d,%d:%08x)\n",nr,pgt,page);
 502                                 *ppage = 0;
 503                                 continue;
 504                         }
 505                         if (mem_map[MAP_NR(page)] & MAP_PAGE_RESERVED)
 506                                 continue;
 507                         ppage = (unsigned long *) (page & 0xfffff000);  
 508                         for (pg = 0 ; pg < 1024 ; pg++,ppage++) {
 509                                 page = *ppage;
 510                                 if (!page)
 511                                         continue;
 512                                 if (page & PAGE_PRESENT) {
 513                                         if (page >= high_memory) {
 514                                                 printk("try_to_unuse: bad page table (%d,%d,%d:%08x)\n",nr,pgt,pg,page);
 515                                                 *ppage = 0;
 516                                         }
 517                                         continue;
 518                                 }
 519                                 if (SWP_TYPE(page) != type)
 520                                         continue;
 521                                 if (!tmp) {
 522                                         tmp = get_free_page(GFP_KERNEL);
 523                                         if (!tmp)
 524                                                 return -ENOMEM;
 525                                         goto repeat;
 526                                 }
 527                                 read_swap_page(page, (char *) tmp);
 528                                 if (*ppage == page) {
 529                                         *ppage = tmp | (PAGE_DIRTY | PAGE_PRIVATE);
 530                                         ++p->rss;
 531                                         swap_free(page);
 532                                         tmp = 0;
 533                                 }
 534                                 goto repeat;
 535                         }
 536                 }
 537         }
 538         free_page(tmp);
 539         return 0;
 540 }
 541 
 542 int sys_swapoff(const char * specialfile)
     /*  */
 543 {
 544         struct swap_info_struct * p;
 545         struct inode * inode;
 546         unsigned int type;
 547         int i;
 548 
 549         if (!suser())
 550                 return -EPERM;
 551         i = namei(specialfile,&inode);
 552         if (i)
 553                 return i;
 554         p = swap_info;
 555         for (type = 0 ; type < nr_swapfiles ; type++,p++) {
 556                 if ((p->flags & SWP_WRITEOK) != SWP_WRITEOK)
 557                         continue;
 558                 if (p->swap_file) {
 559                         if (p->swap_file == inode)
 560                                 break;
 561                 } else {
 562                         if (!S_ISBLK(inode->i_mode))
 563                                 continue;
 564                         if (p->swap_device == inode->i_rdev)
 565                                 break;
 566                 }
 567         }
 568         iput(inode);
 569         if (type >= nr_swapfiles)
 570                 return -EINVAL;
 571         p->flags = SWP_USED;
 572         i = try_to_unuse(type);
 573         if (i) {
 574                 p->flags = SWP_WRITEOK;
 575                 return i;
 576         }
 577         iput(p->swap_file);
 578         p->swap_file = NULL;
 579         p->swap_device = 0;
 580         free_page((long) p->swap_map);
 581         p->swap_map = NULL;
 582         free_page((long) p->swap_lockmap);
 583         p->swap_lockmap = NULL;
 584         p->flags = 0;
 585         return 0;
 586 }
 587 
 588 /*
 589  * Written 01/25/92 by Simmule Turner, heavily changed by Linus.
 590  *
 591  * The swapon system call
 592  */
 593 int sys_swapon(const char * specialfile)
     /*  */
 594 {
 595         struct swap_info_struct * p;
 596         struct inode * swap_inode;
 597         unsigned int type;
 598         char * tmp;
 599         int i,j;
 600 
 601         if (!suser())
 602                 return -EPERM;
 603         p = swap_info;
 604         for (type = 0 ; type < nr_swapfiles ; type++,p++)
 605                 if (!(p->flags & SWP_USED))
 606                         break;
 607         if (type >= MAX_SWAPFILES)
 608                 return -EPERM;
 609         if (type >= nr_swapfiles)
 610                 nr_swapfiles = type+1;
 611         p->flags = SWP_USED;
 612         p->swap_file = NULL;
 613         p->swap_device = 0;
 614         p->swap_map = NULL;
 615         p->swap_lockmap = NULL;
 616         p->lowest_bit = 0;
 617         p->highest_bit = 0;
 618         i = namei(specialfile,&swap_inode);
 619         if (i) {
 620                 p->flags = 0;
 621                 return i;
 622         }
 623         if (swap_inode->i_count != 1) {
 624                 iput(swap_inode);
 625                 p->flags = 0;
 626                 return -EBUSY;
 627         }
 628         if (S_ISBLK(swap_inode->i_mode)) {
 629                 p->swap_device = swap_inode->i_rdev;
 630                 iput(swap_inode);
 631                 if (!p->swap_device) {
 632                         p->flags = 0;
 633                         return -ENODEV;
 634                 }
 635                 for (i = 0 ; i < nr_swapfiles ; i++) {
 636                         if (i == type)
 637                                 continue;
 638                         if (p->swap_device == swap_info[i].swap_device) {
 639                                 p->swap_device = 0;
 640                                 p->flags = 0;
 641                                 return -EBUSY;
 642                         }
 643                 }
 644         } else if (S_ISREG(swap_inode->i_mode))
 645                 p->swap_file = swap_inode;
 646         else {
 647                 iput(swap_inode);
 648                 p->flags = 0;
 649                 return -EINVAL;
 650         }
 651         tmp = (char *) get_free_page(GFP_USER);
 652         p->swap_lockmap = (char *) get_free_page(GFP_USER);
 653         if (!tmp || !p->swap_lockmap) {
 654                 printk("Unable to start swapping: out of memory :-)\n");
 655                 free_page((long) tmp);
 656                 free_page((long) p->swap_lockmap);
 657                 iput(p->swap_file);
 658                 p->swap_device = 0;
 659                 p->swap_file = NULL;
 660                 p->swap_map = NULL;
 661                 p->swap_lockmap = NULL;
 662                 p->flags = 0;
 663                 return -ENOMEM;
 664         }
 665         read_swap_page(SWP_ENTRY(type,0),tmp);
 666         if (strncmp("SWAP-SPACE",tmp+4086,10)) {
 667                 printk("Unable to find swap-space signature\n");
 668                 free_page((long) tmp);
 669                 free_page((long) p->swap_lockmap);
 670                 iput(p->swap_file);
 671                 p->swap_device = 0;
 672                 p->swap_file = NULL;
 673                 p->swap_map = NULL;
 674                 p->swap_lockmap = NULL;
 675                 p->flags = 0;
 676                 return -EINVAL;
 677         }
 678         memset(tmp+4086,0,10);
 679         j = 0;
 680         p->lowest_bit = 0;
 681         p->highest_bit = 0;
 682         for (i = 1 ; i < SWAP_BITS ; i++)
 683                 if (bit(tmp,i)) {
 684                         if (!p->lowest_bit)
 685                                 p->lowest_bit = i;
 686                         p->highest_bit = i;
 687                         j++;
 688                 }
 689         if (!j) {
 690                 printk("Empty swap-file\n");
 691                 free_page((long) tmp);
 692                 free_page((long) p->swap_lockmap);
 693                 iput(p->swap_file);
 694                 p->swap_device = 0;
 695                 p->swap_file = NULL;
 696                 p->swap_map = NULL;
 697                 p->swap_lockmap = NULL;
 698                 p->flags = 0;
 699                 return -EINVAL;
 700         }
 701         i = SWAP_BITS;
 702         while (i--)
 703                 if (bit(tmp,i))
 704                         tmp[i] = 0;
 705                 else
 706                         tmp[i] = 128;
 707         tmp[0] = 128;
 708         p->swap_map = tmp;
 709         p->flags = SWP_WRITEOK;
 710         printk("Adding Swap: %dk swap-space\n",j<<2);
 711         return 0;
 712 }
 713 
 714 void si_swapinfo(struct sysinfo *val)
     /*  */
 715 {
 716         unsigned int i, j;
 717 
 718         val->freeswap = val->totalswap = 0;
 719         for (i = 0; i < nr_swapfiles; i++) {
 720                 if (!(swap_info[i].flags & SWP_USED))
 721                         continue;
 722                 for (j = 0; j < 4096; ++j)
 723                         switch (swap_info[i].swap_map[j]) {
 724                                 case 128:
 725                                         continue;
 726                                 case 0:
 727                                         ++val->freeswap;
 728                                 default:
 729                                         ++val->totalswap;
 730                         }
 731         }
 732         val->freeswap <<= PAGE_SHIFT;
 733         val->totalswap <<= PAGE_SHIFT;
 734         return;
 735 }
/* */
root/mm/swap.c

DEFINITIONS
