158 struct vnode *sw_vp; 159 void *sw_id; 160 swblk_t sw_first; 161 swblk_t sw_end; 162 struct blist *sw_blist; 163 TAILQ_ENTRY(swdevt) sw_list; 164 sw_strategy_t *sw_strategy; 165 sw_close_t *sw_close; 166}; 167 168#define SW_CLOSING 0x04 169 170struct swblock { 171 struct swblock *swb_hnext; 172 vm_object_t swb_object; 173 vm_pindex_t swb_index; 174 int swb_count; 175 daddr_t swb_pages[SWAP_META_PAGES]; 176}; 177 178static struct mtx sw_dev_mtx; 179static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 180static struct swdevt *swdevhd; /* Allocate from here next */ 181static int nswapdev; /* Number of swap devices */ 182int swap_pager_avail; 183static int swdev_syscall_active = 0; /* serialize swap(on|off) */ 184 185static void swapdev_strategy(struct buf *, struct swdevt *sw); 186 187#define SWM_FREE 0x02 /* free, period */ 188#define SWM_POP 0x04 /* pop out */ 189 190int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 191static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 192static int nsw_rcount; /* free read buffers */ 193static int nsw_wcount_sync; /* limit write buffers / synchronous */ 194static int nsw_wcount_async; /* limit write buffers / asynchronous */ 195static int nsw_wcount_async_max;/* assigned maximum */ 196static int nsw_cluster_max; /* maximum VOP I/O allowed */ 197 198static struct swblock **swhash; 199static int swhash_mask; 200static struct mtx swhash_mtx; 201 202static int swap_async_max = 4; /* maximum in-progress async I/O's */ 203static struct sx sw_alloc_sx; 204 205 206SYSCTL_INT(_vm, OID_AUTO, swap_async_max, 207 CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops"); 208 209/* 210 * "named" and "unnamed" anon region objects. Try to reduce the overhead 211 * of searching a named list by hashing it just a little. 212 */ 213 214#define NOBJLISTS 8 215 216#define NOBJLIST(handle) \ 217 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 218 219static struct mtx sw_alloc_mtx; /* protect list manipulation */ 220static struct pagerlst swap_pager_object_list[NOBJLISTS]; 221static uma_zone_t swap_zone; 222 223/* 224 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 225 * calls hooked from other parts of the VM system and do not appear here. 226 * (see vm/swap_pager.h). 227 */ 228static vm_object_t 229 swap_pager_alloc(void *handle, vm_ooffset_t size, 230 vm_prot_t prot, vm_ooffset_t offset); 231static void swap_pager_dealloc(vm_object_t object); 232static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int); 233static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 234static boolean_t 235 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 236static void swap_pager_init(void); 237static void swap_pager_unswapped(vm_page_t); 238static void swap_pager_swapoff(struct swdevt *sp, int *sw_used); 239 240struct pagerops swappagerops = { 241 .pgo_init = swap_pager_init, /* early system initialization of pager */ 242 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 243 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 244 .pgo_getpages = swap_pager_getpages, /* pagein */ 245 .pgo_putpages = swap_pager_putpages, /* pageout */ 246 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 247 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 248}; 249 250/* 251 * dmmax is in page-sized chunks with the new swap system. It was 252 * dev-bsized chunks in the old. dmmax is always a power of 2. 253 * 254 * swap_*() routines are externally accessible. swp_*() routines are 255 * internal. 256 */ 257static int dmmax; 258static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 259static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 260 261SYSCTL_INT(_vm, OID_AUTO, dmmax, 262 CTLFLAG_RD, &dmmax, 0, "Maximum size of a swap block"); 263 264static void swp_sizecheck(void); 265static void swp_pager_async_iodone(struct buf *bp); 266static int swapongeom(struct thread *, struct vnode *); 267static int swaponvp(struct thread *, struct vnode *, u_long); 268 269/* 270 * Swap bitmap functions 271 */ 272static void swp_pager_freeswapspace(daddr_t blk, int npages); 273static daddr_t swp_pager_getswapspace(int npages); 274 275/* 276 * Metadata functions 277 */ 278static struct swblock **swp_pager_hash(vm_object_t object, vm_pindex_t index); 279static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 280static void swp_pager_meta_free(vm_object_t, vm_pindex_t, daddr_t); 281static void swp_pager_meta_free_all(vm_object_t); 282static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 283 284/* 285 * SWP_SIZECHECK() - update swap_pager_full indication 286 * 287 * update the swap_pager_almost_full indication and warn when we are 288 * about to run out of swap space, using lowat/hiwat hysteresis. 289 * 290 * Clear swap_pager_full ( task killing ) indication when lowat is met. 291 * 292 * No restrictions on call 293 * This routine may not block. 294 * This routine must be called at splvm() 295 */ 296static void 297swp_sizecheck(void) 298{ 299 300 if (swap_pager_avail < nswap_lowat) { 301 if (swap_pager_almost_full == 0) { 302 printf("swap_pager: out of swap space\n"); 303 swap_pager_almost_full = 1; 304 } 305 } else { 306 swap_pager_full = 0; 307 if (swap_pager_avail > nswap_hiwat) 308 swap_pager_almost_full = 0; 309 } 310} 311 312/* 313 * SWP_PAGER_HASH() - hash swap meta data 314 * 315 * This is an helper function which hashes the swapblk given 316 * the object and page index. It returns a pointer to a pointer 317 * to the object, or a pointer to a NULL pointer if it could not 318 * find a swapblk. 319 * 320 * This routine must be called at splvm(). 321 */ 322static struct swblock ** 323swp_pager_hash(vm_object_t object, vm_pindex_t index) 324{ 325 struct swblock **pswap; 326 struct swblock *swap; 327 328 index &= ~(vm_pindex_t)SWAP_META_MASK; 329 pswap = &swhash[(index ^ (int)(intptr_t)object) & swhash_mask]; 330 while ((swap = *pswap) != NULL) { 331 if (swap->swb_object == object && 332 swap->swb_index == index 333 ) { 334 break; 335 } 336 pswap = &swap->swb_hnext; 337 } 338 return (pswap); 339} 340 341/* 342 * SWAP_PAGER_INIT() - initialize the swap pager! 343 * 344 * Expected to be started from system init. NOTE: This code is run 345 * before much else so be careful what you depend on. Most of the VM 346 * system has yet to be initialized at this point. 347 */ 348static void 349swap_pager_init(void) 350{ 351 /* 352 * Initialize object lists 353 */ 354 int i; 355 356 for (i = 0; i < NOBJLISTS; ++i) 357 TAILQ_INIT(&swap_pager_object_list[i]); 358 mtx_init(&sw_alloc_mtx, "swap_pager list", NULL, MTX_DEF); 359 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 360 361 /* 362 * Device Stripe, in PAGE_SIZE'd blocks 363 */ 364 dmmax = SWB_NPAGES * 2; 365} 366 367/* 368 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 369 * 370 * Expected to be started from pageout process once, prior to entering 371 * its main loop. 372 */ 373void 374swap_pager_swap_init(void) 375{ 376 int n, n2; 377 378 /* 379 * Number of in-transit swap bp operations. Don't 380 * exhaust the pbufs completely. Make sure we 381 * initialize workable values (0 will work for hysteresis 382 * but it isn't very efficient). 383 * 384 * The nsw_cluster_max is constrained by the bp->b_pages[] 385 * array (MAXPHYS/PAGE_SIZE) and our locally defined 386 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 387 * constrained by the swap device interleave stripe size. 388 * 389 * Currently we hardwire nsw_wcount_async to 4. This limit is 390 * designed to prevent other I/O from having high latencies due to 391 * our pageout I/O. The value 4 works well for one or two active swap 392 * devices but is probably a little low if you have more. Even so, 393 * a higher value would probably generate only a limited improvement 394 * with three or four active swap devices since the system does not 395 * typically have to pageout at extreme bandwidths. We will want 396 * at least 2 per swap devices, and 4 is a pretty good value if you 397 * have one NFS swap device due to the command/ack latency over NFS. 398 * So it all works out pretty well. 399 */ 400 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER); 401 402 mtx_lock(&pbuf_mtx); 403 nsw_rcount = (nswbuf + 1) / 2; 404 nsw_wcount_sync = (nswbuf + 3) / 4; 405 nsw_wcount_async = 4; 406 nsw_wcount_async_max = nsw_wcount_async; 407 mtx_unlock(&pbuf_mtx); 408 409 /* 410 * Initialize our zone. Right now I'm just guessing on the number 411 * we need based on the number of pages in the system. Each swblock 412 * can hold 16 pages, so this is probably overkill. This reservation 413 * is typically limited to around 32MB by default. 414 */ 415 n = cnt.v_page_count / 2; 416 if (maxswzone && n > maxswzone / sizeof(struct swblock)) 417 n = maxswzone / sizeof(struct swblock); 418 n2 = n; 419 swap_zone = uma_zcreate("SWAPMETA", sizeof(struct swblock), NULL, NULL, 420 NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE | UMA_ZONE_VM); 421 do { 422 if (uma_zone_set_obj(swap_zone, NULL, n)) 423 break; 424 /* 425 * if the allocation failed, try a zone two thirds the 426 * size of the previous attempt. 427 */ 428 n -= ((n + 2) / 3); 429 } while (n > 0); 430 if (swap_zone == NULL) 431 panic("failed to create swap_zone."); 432 if (n2 != n) 433 printf("Swap zone entries reduced from %d to %d.\n", n2, n); 434 n2 = n; 435 436 /* 437 * Initialize our meta-data hash table. The swapper does not need to 438 * be quite as efficient as the VM system, so we do not use an 439 * oversized hash table. 440 * 441 * n: size of hash table, must be power of 2 442 * swhash_mask: hash table index mask 443 */ 444 for (n = 1; n < n2 / 8; n *= 2) 445 ; 446 swhash = malloc(sizeof(struct swblock *) * n, M_VMPGDATA, M_WAITOK | M_ZERO); 447 swhash_mask = n - 1; 448 mtx_init(&swhash_mtx, "swap_pager swhash", NULL, MTX_DEF); 449} 450 451/* 452 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 453 * its metadata structures. 454 * 455 * This routine is called from the mmap and fork code to create a new 456 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object 457 * and then converting it with swp_pager_meta_build(). 458 * 459 * This routine may block in vm_object_allocate() and create a named 460 * object lookup race, so we must interlock. We must also run at 461 * splvm() for the object lookup to handle races with interrupts, but 462 * we do not have to maintain splvm() in between the lookup and the 463 * add because (I believe) it is not possible to attempt to create 464 * a new swap object w/handle when a default object with that handle 465 * already exists. 466 * 467 * MPSAFE 468 */ 469static vm_object_t 470swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 471 vm_ooffset_t offset) 472{ 473 vm_object_t object; 474 vm_pindex_t pindex; 475 476 pindex = OFF_TO_IDX(offset + PAGE_MASK + size); 477 478 if (handle) { 479 mtx_lock(&Giant); 480 /* 481 * Reference existing named region or allocate new one. There 482 * should not be a race here against swp_pager_meta_build() 483 * as called from vm_page_remove() in regards to the lookup 484 * of the handle. 485 */ 486 sx_xlock(&sw_alloc_sx); 487 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 488 489 if (object != NULL) { 490 vm_object_reference(object); 491 } else { 492 object = vm_object_allocate(OBJT_DEFAULT, pindex); 493 object->handle = handle; 494 495 VM_OBJECT_LOCK(object); 496 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 497 VM_OBJECT_UNLOCK(object); 498 } 499 sx_xunlock(&sw_alloc_sx); 500 mtx_unlock(&Giant); 501 } else { 502 object = vm_object_allocate(OBJT_DEFAULT, pindex); 503 504 VM_OBJECT_LOCK(object); 505 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 506 VM_OBJECT_UNLOCK(object); 507 } 508 return (object); 509} 510 511/* 512 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 513 * 514 * The swap backing for the object is destroyed. The code is 515 * designed such that we can reinstantiate it later, but this 516 * routine is typically called only when the entire object is 517 * about to be destroyed. 518 * 519 * This routine may block, but no longer does. 520 * 521 * The object must be locked or unreferenceable. 522 */ 523static void 524swap_pager_dealloc(vm_object_t object) 525{ 526 int s; 527 528 /* 529 * Remove from list right away so lookups will fail if we block for 530 * pageout completion. 531 */ 532 if (object->handle != NULL) { 533 mtx_lock(&sw_alloc_mtx); 534 TAILQ_REMOVE(NOBJLIST(object->handle), object, pager_object_list); 535 mtx_unlock(&sw_alloc_mtx); 536 } 537 538 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 539 vm_object_pip_wait(object, "swpdea"); 540 541 /* 542 * Free all remaining metadata. We only bother to free it from 543 * the swap meta data. We do not attempt to free swapblk's still 544 * associated with vm_page_t's for this object. We do not care 545 * if paging is still in progress on some objects. 546 */ 547 s = splvm(); 548 swp_pager_meta_free_all(object); 549 splx(s); 550} 551 552/************************************************************************ 553 * SWAP PAGER BITMAP ROUTINES * 554 ************************************************************************/ 555 556/* 557 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 558 * 559 * Allocate swap for the requested number of pages. The starting 560 * swap block number (a page index) is returned or SWAPBLK_NONE 561 * if the allocation failed. 562 * 563 * Also has the side effect of advising that somebody made a mistake 564 * when they configured swap and didn't configure enough. 565 * 566 * Must be called at splvm() to avoid races with bitmap frees from 567 * vm_page_remove() aka swap_pager_page_removed(). 568 * 569 * This routine may not block 570 * This routine must be called at splvm(). 571 * 572 * We allocate in round-robin fashion from the configured devices. 573 */ 574static daddr_t 575swp_pager_getswapspace(int npages) 576{ 577 daddr_t blk; 578 struct swdevt *sp; 579 int i; 580 581 blk = SWAPBLK_NONE; 582 mtx_lock(&sw_dev_mtx); 583 sp = swdevhd; 584 for (i = 0; i < nswapdev; i++) { 585 if (sp == NULL) 586 sp = TAILQ_FIRST(&swtailq); 587 if (!(sp->sw_flags & SW_CLOSING)) { 588 blk = blist_alloc(sp->sw_blist, npages); 589 if (blk != SWAPBLK_NONE) { 590 blk += sp->sw_first; 591 sp->sw_used += npages; 592 swap_pager_avail -= npages; 593 swp_sizecheck(); 594 swdevhd = TAILQ_NEXT(sp, sw_list); 595 goto done; 596 } 597 } 598 sp = TAILQ_NEXT(sp, sw_list); 599 } 600 if (swap_pager_full != 2) { 601 printf("swap_pager_getswapspace(%d): failed\n", npages); 602 swap_pager_full = 2; 603 swap_pager_almost_full = 1; 604 } 605 swdevhd = NULL; 606done: 607 mtx_unlock(&sw_dev_mtx); 608 return (blk); 609} 610 611static struct swdevt * 612swp_pager_find_dev(daddr_t blk) 613{ 614 struct swdevt *sp; 615 616 mtx_lock(&sw_dev_mtx); 617 TAILQ_FOREACH(sp, &swtailq, sw_list) { 618 if (blk >= sp->sw_first && blk < sp->sw_end) { 619 mtx_unlock(&sw_dev_mtx); 620 return (sp); 621 } 622 } 623 panic("Swapdev not found"); 624} 625 626static void 627swp_pager_strategy(struct buf *bp) 628{ 629 struct swdevt *sp; 630 631 mtx_lock(&sw_dev_mtx); 632 TAILQ_FOREACH(sp, &swtailq, sw_list) { 633 if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) { 634 mtx_unlock(&sw_dev_mtx); 635 sp->sw_strategy(bp, sp); 636 return; 637 } 638 } 639 panic("Swapdev not found"); 640} 641 642 643/* 644 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 645 * 646 * This routine returns the specified swap blocks back to the bitmap. 647 * 648 * Note: This routine may not block (it could in the old swap code), 649 * and through the use of the new blist routines it does not block. 650 * 651 * We must be called at splvm() to avoid races with bitmap frees from 652 * vm_page_remove() aka swap_pager_page_removed(). 653 * 654 * This routine may not block 655 * This routine must be called at splvm(). 656 */ 657static void 658swp_pager_freeswapspace(daddr_t blk, int npages) 659{ 660 struct swdevt *sp; 661 662 mtx_lock(&sw_dev_mtx); 663 TAILQ_FOREACH(sp, &swtailq, sw_list) { 664 if (blk >= sp->sw_first && blk < sp->sw_end) { 665 sp->sw_used -= npages; 666 /* 667 * If we are attempting to stop swapping on 668 * this device, we don't want to mark any 669 * blocks free lest they be reused. 670 */ 671 if ((sp->sw_flags & SW_CLOSING) == 0) { 672 blist_free(sp->sw_blist, blk - sp->sw_first, 673 npages); 674 swap_pager_avail += npages; 675 swp_sizecheck(); 676 } 677 mtx_unlock(&sw_dev_mtx); 678 return; 679 } 680 } 681 panic("Swapdev not found"); 682} 683 684/* 685 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 686 * range within an object. 687 * 688 * This is a globally accessible routine. 689 * 690 * This routine removes swapblk assignments from swap metadata. 691 * 692 * The external callers of this routine typically have already destroyed 693 * or renamed vm_page_t's associated with this range in the object so 694 * we should be ok. 695 * 696 * This routine may be called at any spl. We up our spl to splvm temporarily 697 * in order to perform the metadata removal. 698 */ 699void 700swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 701{ 702 int s = splvm(); 703 704 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 705 swp_pager_meta_free(object, start, size); 706 splx(s); 707} 708 709/* 710 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 711 * 712 * Assigns swap blocks to the specified range within the object. The 713 * swap blocks are not zerod. Any previous swap assignment is destroyed. 714 * 715 * Returns 0 on success, -1 on failure. 716 */ 717int 718swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 719{ 720 int s; 721 int n = 0; 722 daddr_t blk = SWAPBLK_NONE; 723 vm_pindex_t beg = start; /* save start index */ 724 725 s = splvm(); 726 VM_OBJECT_LOCK(object); 727 while (size) { 728 if (n == 0) { 729 n = BLIST_MAX_ALLOC; 730 while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) { 731 n >>= 1; 732 if (n == 0) { 733 swp_pager_meta_free(object, beg, start - beg); 734 VM_OBJECT_UNLOCK(object); 735 splx(s); 736 return (-1); 737 } 738 } 739 } 740 swp_pager_meta_build(object, start, blk); 741 --size; 742 ++start; 743 ++blk; 744 --n; 745 } 746 swp_pager_meta_free(object, start, n); 747 VM_OBJECT_UNLOCK(object); 748 splx(s); 749 return (0); 750} 751 752/* 753 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 754 * and destroy the source. 755 * 756 * Copy any valid swapblks from the source to the destination. In 757 * cases where both the source and destination have a valid swapblk, 758 * we keep the destination's. 759 * 760 * This routine is allowed to block. It may block allocating metadata 761 * indirectly through swp_pager_meta_build() or if paging is still in 762 * progress on the source. 763 * 764 * This routine can be called at any spl 765 * 766 * XXX vm_page_collapse() kinda expects us not to block because we 767 * supposedly do not need to allocate memory, but for the moment we 768 * *may* have to get a little memory from the zone allocator, but 769 * it is taken from the interrupt memory. We should be ok. 770 * 771 * The source object contains no vm_page_t's (which is just as well) 772 * 773 * The source object is of type OBJT_SWAP. 774 * 775 * The source and destination objects must be locked or 776 * inaccessible (XXX are they ?) 777 */ 778void 779swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 780 vm_pindex_t offset, int destroysource) 781{ 782 vm_pindex_t i; 783 int s; 784 785 VM_OBJECT_LOCK_ASSERT(srcobject, MA_OWNED); 786 VM_OBJECT_LOCK_ASSERT(dstobject, MA_OWNED); 787 788 s = splvm(); 789 /* 790 * If destroysource is set, we remove the source object from the 791 * swap_pager internal queue now. 792 */ 793 if (destroysource) { 794 if (srcobject->handle != NULL) { 795 mtx_lock(&sw_alloc_mtx); 796 TAILQ_REMOVE( 797 NOBJLIST(srcobject->handle), 798 srcobject, 799 pager_object_list 800 ); 801 mtx_unlock(&sw_alloc_mtx); 802 } 803 } 804 805 /* 806 * transfer source to destination. 807 */ 808 for (i = 0; i < dstobject->size; ++i) { 809 daddr_t dstaddr; 810 811 /* 812 * Locate (without changing) the swapblk on the destination, 813 * unless it is invalid in which case free it silently, or 814 * if the destination is a resident page, in which case the 815 * source is thrown away. 816 */ 817 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 818 819 if (dstaddr == SWAPBLK_NONE) { 820 /* 821 * Destination has no swapblk and is not resident, 822 * copy source. 823 */ 824 daddr_t srcaddr; 825 826 srcaddr = swp_pager_meta_ctl( 827 srcobject, 828 i + offset, 829 SWM_POP 830 ); 831 832 if (srcaddr != SWAPBLK_NONE) { 833 /* 834 * swp_pager_meta_build() can sleep. 835 */ 836 vm_object_pip_add(srcobject, 1); 837 VM_OBJECT_UNLOCK(srcobject); 838 vm_object_pip_add(dstobject, 1); 839 swp_pager_meta_build(dstobject, i, srcaddr); 840 vm_object_pip_wakeup(dstobject); 841 VM_OBJECT_LOCK(srcobject); 842 vm_object_pip_wakeup(srcobject); 843 } 844 } else { 845 /* 846 * Destination has valid swapblk or it is represented 847 * by a resident page. We destroy the sourceblock. 848 */ 849 850 swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE); 851 } 852 } 853 854 /* 855 * Free left over swap blocks in source. 856 * 857 * We have to revert the type to OBJT_DEFAULT so we do not accidently 858 * double-remove the object from the swap queues. 859 */ 860 if (destroysource) { 861 swp_pager_meta_free_all(srcobject); 862 /* 863 * Reverting the type is not necessary, the caller is going 864 * to destroy srcobject directly, but I'm doing it here 865 * for consistency since we've removed the object from its 866 * queues. 867 */ 868 srcobject->type = OBJT_DEFAULT; 869 } 870 splx(s); 871} 872 873/* 874 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 875 * the requested page. 876 * 877 * We determine whether good backing store exists for the requested 878 * page and return TRUE if it does, FALSE if it doesn't. 879 * 880 * If TRUE, we also try to determine how much valid, contiguous backing 881 * store exists before and after the requested page within a reasonable 882 * distance. We do not try to restrict it to the swap device stripe 883 * (that is handled in getpages/putpages). It probably isn't worth 884 * doing here. 885 */ 886static boolean_t 887swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after) 888{ 889 daddr_t blk0; 890 int s; 891 892 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 893 /* 894 * do we have good backing store at the requested index ? 895 */ 896 s = splvm(); 897 blk0 = swp_pager_meta_ctl(object, pindex, 0); 898 899 if (blk0 == SWAPBLK_NONE) { 900 splx(s); 901 if (before) 902 *before = 0; 903 if (after) 904 *after = 0; 905 return (FALSE); 906 } 907 908 /* 909 * find backwards-looking contiguous good backing store 910 */ 911 if (before != NULL) { 912 int i; 913 914 for (i = 1; i < (SWB_NPAGES/2); ++i) { 915 daddr_t blk; 916 917 if (i > pindex) 918 break; 919 blk = swp_pager_meta_ctl(object, pindex - i, 0); 920 if (blk != blk0 - i) 921 break; 922 } 923 *before = (i - 1); 924 } 925 926 /* 927 * find forward-looking contiguous good backing store 928 */ 929 if (after != NULL) { 930 int i; 931 932 for (i = 1; i < (SWB_NPAGES/2); ++i) { 933 daddr_t blk; 934 935 blk = swp_pager_meta_ctl(object, pindex + i, 0); 936 if (blk != blk0 + i) 937 break; 938 } 939 *after = (i - 1); 940 } 941 splx(s); 942 return (TRUE); 943} 944 945/* 946 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 947 * 948 * This removes any associated swap backing store, whether valid or 949 * not, from the page. 950 * 951 * This routine is typically called when a page is made dirty, at 952 * which point any associated swap can be freed. MADV_FREE also 953 * calls us in a special-case situation 954 * 955 * NOTE!!! If the page is clean and the swap was valid, the caller 956 * should make the page dirty before calling this routine. This routine 957 * does NOT change the m->dirty status of the page. Also: MADV_FREE 958 * depends on it. 959 * 960 * This routine may not block 961 * This routine must be called at splvm() 962 */ 963static void 964swap_pager_unswapped(vm_page_t m) 965{ 966 967 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 968 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); 969} 970 971/* 972 * SWAP_PAGER_GETPAGES() - bring pages in from swap 973 * 974 * Attempt to retrieve (m, count) pages from backing store, but make 975 * sure we retrieve at least m[reqpage]. We try to load in as large 976 * a chunk surrounding m[reqpage] as is contiguous in swap and which 977 * belongs to the same object. 978 * 979 * The code is designed for asynchronous operation and 980 * immediate-notification of 'reqpage' but tends not to be 981 * used that way. Please do not optimize-out this algorithmic 982 * feature, I intend to improve on it in the future. 983 * 984 * The parent has a single vm_object_pip_add() reference prior to 985 * calling us and we should return with the same. 986 * 987 * The parent has BUSY'd the pages. We should return with 'm' 988 * left busy, but the others adjusted. 989 */ 990static int 991swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage) 992{ 993 struct buf *bp; 994 vm_page_t mreq; 995 int s; 996 int i; 997 int j; 998 daddr_t blk; 999 1000 mreq = m[reqpage]; 1001 1002 KASSERT(mreq->object == object, 1003 ("swap_pager_getpages: object mismatch %p/%p", 1004 object, mreq->object)); 1005 1006 /* 1007 * Calculate range to retrieve. The pages have already been assigned 1008 * their swapblks. We require a *contiguous* range but we know it to 1009 * not span devices. If we do not supply it, bad things 1010 * happen. Note that blk, iblk & jblk can be SWAPBLK_NONE, but the 1011 * loops are set up such that the case(s) are handled implicitly. 1012 * 1013 * The swp_*() calls must be made at splvm(). vm_page_free() does 1014 * not need to be, but it will go a little faster if it is. 1015 */ 1016 s = splvm(); 1017 blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0); 1018 1019 for (i = reqpage - 1; i >= 0; --i) { 1020 daddr_t iblk; 1021 1022 iblk = swp_pager_meta_ctl(m[i]->object, m[i]->pindex, 0); 1023 if (blk != iblk + (reqpage - i)) 1024 break; 1025 } 1026 ++i; 1027 1028 for (j = reqpage + 1; j < count; ++j) { 1029 daddr_t jblk; 1030 1031 jblk = swp_pager_meta_ctl(m[j]->object, m[j]->pindex, 0); 1032 if (blk != jblk - (j - reqpage)) 1033 break; 1034 } 1035 1036 /* 1037 * free pages outside our collection range. Note: we never free 1038 * mreq, it must remain busy throughout. 1039 */ 1040 vm_page_lock_queues(); 1041 { 1042 int k; 1043 1044 for (k = 0; k < i; ++k) 1045 vm_page_free(m[k]); 1046 for (k = j; k < count; ++k) 1047 vm_page_free(m[k]); 1048 } 1049 vm_page_unlock_queues(); 1050 splx(s); 1051 1052 1053 /* 1054 * Return VM_PAGER_FAIL if we have nothing to do. Return mreq 1055 * still busy, but the others unbusied. 1056 */ 1057 if (blk == SWAPBLK_NONE) 1058 return (VM_PAGER_FAIL); 1059 1060 /* 1061 * Getpbuf() can sleep. 1062 */ 1063 VM_OBJECT_UNLOCK(object); 1064 /* 1065 * Get a swap buffer header to perform the IO 1066 */ 1067 bp = getpbuf(&nsw_rcount); 1068 bp->b_flags |= B_PAGING; 1069 1070 /* 1071 * map our page(s) into kva for input 1072 */ 1073 pmap_qenter((vm_offset_t)bp->b_data, m + i, j - i); 1074 1075 bp->b_iocmd = BIO_READ; 1076 bp->b_iodone = swp_pager_async_iodone; 1077 bp->b_rcred = crhold(thread0.td_ucred); 1078 bp->b_wcred = crhold(thread0.td_ucred); 1079 bp->b_blkno = blk - (reqpage - i); 1080 bp->b_bcount = PAGE_SIZE * (j - i); 1081 bp->b_bufsize = PAGE_SIZE * (j - i); 1082 bp->b_pager.pg_reqpage = reqpage - i; 1083 1084 VM_OBJECT_LOCK(object); 1085 vm_page_lock_queues(); 1086 { 1087 int k; 1088 1089 for (k = i; k < j; ++k) { 1090 bp->b_pages[k - i] = m[k]; 1091 vm_page_flag_set(m[k], PG_SWAPINPROG); 1092 } 1093 } 1094 vm_page_unlock_queues(); 1095 VM_OBJECT_UNLOCK(object); 1096 bp->b_npages = j - i; 1097 1098 cnt.v_swapin++; 1099 cnt.v_swappgsin += bp->b_npages; 1100 1101 /* 1102 * We still hold the lock on mreq, and our automatic completion routine 1103 * does not remove it. 1104 */ 1105 VM_OBJECT_LOCK(mreq->object); 1106 vm_object_pip_add(mreq->object, bp->b_npages); 1107 VM_OBJECT_UNLOCK(mreq->object); 1108 1109 /* 1110 * perform the I/O. NOTE!!! bp cannot be considered valid after 1111 * this point because we automatically release it on completion. 1112 * Instead, we look at the one page we are interested in which we 1113 * still hold a lock on even through the I/O completion. 1114 * 1115 * The other pages in our m[] array are also released on completion, 1116 * so we cannot assume they are valid anymore either. 1117 * 1118 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1119 */ 1120 BUF_KERNPROC(bp); 1121 swp_pager_strategy(bp); 1122 1123 /* 1124 * wait for the page we want to complete. PG_SWAPINPROG is always 1125 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1126 * is set in the meta-data. 1127 */ 1128 s = splvm(); 1129 vm_page_lock_queues(); 1130 while ((mreq->flags & PG_SWAPINPROG) != 0) { 1131 vm_page_flag_set(mreq, PG_WANTED | PG_REFERENCED); 1132 cnt.v_intrans++; 1133 if (msleep(mreq, &vm_page_queue_mtx, PSWP, "swread", hz*20)) { 1134 printf( 1135 "swap_pager: indefinite wait buffer: device:" 1136 " %s, blkno: %ld, size: %ld\n", 1137 devtoname(bp->b_dev), (long)bp->b_blkno, 1138 bp->b_bcount 1139 ); 1140 } 1141 } 1142 vm_page_unlock_queues(); 1143 splx(s); 1144 1145 VM_OBJECT_LOCK(mreq->object); 1146 /* 1147 * mreq is left busied after completion, but all the other pages 1148 * are freed. If we had an unrecoverable read error the page will 1149 * not be valid. 1150 */ 1151 if (mreq->valid != VM_PAGE_BITS_ALL) { 1152 return (VM_PAGER_ERROR); 1153 } else { 1154 return (VM_PAGER_OK); 1155 } 1156 1157 /* 1158 * A final note: in a low swap situation, we cannot deallocate swap 1159 * and mark a page dirty here because the caller is likely to mark 1160 * the page clean when we return, causing the page to possibly revert 1161 * to all-zero's later. 1162 */ 1163} 1164 1165/* 1166 * swap_pager_putpages: 1167 * 1168 * Assign swap (if necessary) and initiate I/O on the specified pages. 1169 * 1170 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1171 * are automatically converted to SWAP objects. 1172 * 1173 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1174 * vm_page reservation system coupled with properly written VFS devices 1175 * should ensure that no low-memory deadlock occurs. This is an area 1176 * which needs work. 1177 * 1178 * The parent has N vm_object_pip_add() references prior to 1179 * calling us and will remove references for rtvals[] that are 1180 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1181 * completion. 1182 * 1183 * The parent has soft-busy'd the pages it passes us and will unbusy 1184 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1185 * We need to unbusy the rest on I/O completion. 1186 */ 1187void 1188swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1189 boolean_t sync, int *rtvals) 1190{ 1191 int i; 1192 int n = 0; 1193 1194 GIANT_REQUIRED; 1195 if (count && m[0]->object != object) { 1196 panic("swap_pager_getpages: object mismatch %p/%p", 1197 object, 1198 m[0]->object 1199 ); 1200 } 1201 1202 /* 1203 * Step 1 1204 * 1205 * Turn object into OBJT_SWAP 1206 * check for bogus sysops 1207 * force sync if not pageout process 1208 */ 1209 if (object->type != OBJT_SWAP) 1210 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1211 VM_OBJECT_UNLOCK(object); 1212 1213 if (curproc != pageproc) 1214 sync = TRUE; 1215 1216 /* 1217 * Step 2 1218 * 1219 * Update nsw parameters from swap_async_max sysctl values. 1220 * Do not let the sysop crash the machine with bogus numbers. 1221 */ 1222 mtx_lock(&pbuf_mtx); 1223 if (swap_async_max != nsw_wcount_async_max) { 1224 int n; 1225 int s; 1226 1227 /* 1228 * limit range 1229 */ 1230 if ((n = swap_async_max) > nswbuf / 2) 1231 n = nswbuf / 2; 1232 if (n < 1) 1233 n = 1; 1234 swap_async_max = n; 1235 1236 /* 1237 * Adjust difference ( if possible ). If the current async 1238 * count is too low, we may not be able to make the adjustment 1239 * at this time. 1240 */ 1241 s = splvm(); 1242 n -= nsw_wcount_async_max; 1243 if (nsw_wcount_async + n >= 0) { 1244 nsw_wcount_async += n; 1245 nsw_wcount_async_max += n; 1246 wakeup(&nsw_wcount_async); 1247 } 1248 splx(s); 1249 } 1250 mtx_unlock(&pbuf_mtx); 1251 1252 /* 1253 * Step 3 1254 * 1255 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1256 * The page is left dirty until the pageout operation completes 1257 * successfully. 1258 */ 1259 for (i = 0; i < count; i += n) { 1260 int s; 1261 int j; 1262 struct buf *bp; 1263 daddr_t blk; 1264 1265 /* 1266 * Maximum I/O size is limited by a number of factors. 1267 */ 1268 n = min(BLIST_MAX_ALLOC, count - i); 1269 n = min(n, nsw_cluster_max); 1270 1271 s = splvm(); 1272 1273 /* 1274 * Get biggest block of swap we can. If we fail, fall 1275 * back and try to allocate a smaller block. Don't go 1276 * overboard trying to allocate space if it would overly 1277 * fragment swap. 1278 */ 1279 while ( 1280 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE && 1281 n > 4 1282 ) { 1283 n >>= 1; 1284 } 1285 if (blk == SWAPBLK_NONE) { 1286 for (j = 0; j < n; ++j) 1287 rtvals[i+j] = VM_PAGER_FAIL; 1288 splx(s); 1289 continue; 1290 } 1291 1292 /* 1293 * All I/O parameters have been satisfied, build the I/O 1294 * request and assign the swap space. 1295 */ 1296 if (sync == TRUE) { 1297 bp = getpbuf(&nsw_wcount_sync); 1298 } else { 1299 bp = getpbuf(&nsw_wcount_async); 1300 bp->b_flags = B_ASYNC; 1301 } 1302 bp->b_flags |= B_PAGING; 1303 bp->b_iocmd = BIO_WRITE; 1304 1305 pmap_qenter((vm_offset_t)bp->b_data, &m[i], n); 1306 1307 bp->b_rcred = crhold(thread0.td_ucred); 1308 bp->b_wcred = crhold(thread0.td_ucred); 1309 bp->b_bcount = PAGE_SIZE * n; 1310 bp->b_bufsize = PAGE_SIZE * n; 1311 bp->b_blkno = blk; 1312 1313 VM_OBJECT_LOCK(object); 1314 for (j = 0; j < n; ++j) { 1315 vm_page_t mreq = m[i+j]; 1316 1317 swp_pager_meta_build( 1318 mreq->object, 1319 mreq->pindex, 1320 blk + j 1321 ); 1322 vm_page_dirty(mreq); 1323 rtvals[i+j] = VM_PAGER_OK; 1324 1325 vm_page_lock_queues(); 1326 vm_page_flag_set(mreq, PG_SWAPINPROG); 1327 vm_page_unlock_queues(); 1328 bp->b_pages[j] = mreq; 1329 } 1330 VM_OBJECT_UNLOCK(object); 1331 bp->b_npages = n; 1332 /* 1333 * Must set dirty range for NFS to work. 1334 */ 1335 bp->b_dirtyoff = 0; 1336 bp->b_dirtyend = bp->b_bcount; 1337 1338 cnt.v_swapout++; 1339 cnt.v_swappgsout += bp->b_npages; 1340 1341 splx(s); 1342 1343 /* 1344 * asynchronous 1345 * 1346 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1347 */ 1348 if (sync == FALSE) { 1349 bp->b_iodone = swp_pager_async_iodone; 1350 BUF_KERNPROC(bp); 1351 swp_pager_strategy(bp); 1352 1353 for (j = 0; j < n; ++j) 1354 rtvals[i+j] = VM_PAGER_PEND; 1355 /* restart outter loop */ 1356 continue; 1357 } 1358 1359 /* 1360 * synchronous 1361 * 1362 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1363 */ 1364 bp->b_iodone = bdone; 1365 swp_pager_strategy(bp); 1366 1367 /* 1368 * Wait for the sync I/O to complete, then update rtvals. 1369 * We just set the rtvals[] to VM_PAGER_PEND so we can call 1370 * our async completion routine at the end, thus avoiding a 1371 * double-free. 1372 */ 1373 s = splbio(); 1374 bwait(bp, PVM, "swwrt"); 1375 for (j = 0; j < n; ++j) 1376 rtvals[i+j] = VM_PAGER_PEND; 1377 /* 1378 * Now that we are through with the bp, we can call the 1379 * normal async completion, which frees everything up. 1380 */ 1381 swp_pager_async_iodone(bp); 1382 splx(s); 1383 } 1384 VM_OBJECT_LOCK(object); 1385} 1386 1387/* 1388 * swp_pager_async_iodone: 1389 * 1390 * Completion routine for asynchronous reads and writes from/to swap. 1391 * Also called manually by synchronous code to finish up a bp. 1392 * 1393 * For READ operations, the pages are PG_BUSY'd. For WRITE operations, 1394 * the pages are vm_page_t->busy'd. For READ operations, we PG_BUSY 1395 * unbusy all pages except the 'main' request page. For WRITE 1396 * operations, we vm_page_t->busy'd unbusy all pages ( we can do this 1397 * because we marked them all VM_PAGER_PEND on return from putpages ). 1398 * 1399 * This routine may not block. 1400 * This routine is called at splbio() or better 1401 * 1402 * We up ourselves to splvm() as required for various vm_page related 1403 * calls. 1404 */ 1405static void 1406swp_pager_async_iodone(struct buf *bp) 1407{ 1408 int s; 1409 int i; 1410 vm_object_t object = NULL; 1411 1412 bp->b_flags |= B_DONE; 1413 1414 /* 1415 * report error 1416 */ 1417 if (bp->b_ioflags & BIO_ERROR) { 1418 printf( 1419 "swap_pager: I/O error - %s failed; blkno %ld," 1420 "size %ld, error %d\n", 1421 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1422 (long)bp->b_blkno, 1423 (long)bp->b_bcount, 1424 bp->b_error 1425 ); 1426 } 1427 1428 /* 1429 * set object, raise to splvm(). 1430 */ 1431 s = splvm(); 1432 1433 /* 1434 * remove the mapping for kernel virtual 1435 */ 1436 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1437 1438 if (bp->b_npages) { 1439 object = bp->b_pages[0]->object; 1440 VM_OBJECT_LOCK(object); 1441 } 1442 vm_page_lock_queues(); 1443 /* 1444 * cleanup pages. If an error occurs writing to swap, we are in 1445 * very serious trouble. If it happens to be a disk error, though, 1446 * we may be able to recover by reassigning the swap later on. So 1447 * in this case we remove the m->swapblk assignment for the page 1448 * but do not free it in the rlist. The errornous block(s) are thus 1449 * never reallocated as swap. Redirty the page and continue. 1450 */ 1451 for (i = 0; i < bp->b_npages; ++i) { 1452 vm_page_t m = bp->b_pages[i]; 1453 1454 vm_page_flag_clear(m, PG_SWAPINPROG); 1455 1456 if (bp->b_ioflags & BIO_ERROR) { 1457 /* 1458 * If an error occurs I'd love to throw the swapblk 1459 * away without freeing it back to swapspace, so it 1460 * can never be used again. But I can't from an 1461 * interrupt. 1462 */ 1463 if (bp->b_iocmd == BIO_READ) { 1464 /* 1465 * When reading, reqpage needs to stay 1466 * locked for the parent, but all other 1467 * pages can be freed. We still want to 1468 * wakeup the parent waiting on the page, 1469 * though. ( also: pg_reqpage can be -1 and 1470 * not match anything ). 1471 * 1472 * We have to wake specifically requested pages 1473 * up too because we cleared PG_SWAPINPROG and 1474 * someone may be waiting for that. 1475 * 1476 * NOTE: for reads, m->dirty will probably 1477 * be overridden by the original caller of 1478 * getpages so don't play cute tricks here. 1479 * 1480 * XXX IT IS NOT LEGAL TO FREE THE PAGE HERE 1481 * AS THIS MESSES WITH object->memq, and it is 1482 * not legal to mess with object->memq from an 1483 * interrupt. 1484 */ 1485 m->valid = 0; 1486 if (i != bp->b_pager.pg_reqpage) 1487 vm_page_free(m); 1488 else 1489 vm_page_flash(m); 1490 /* 1491 * If i == bp->b_pager.pg_reqpage, do not wake 1492 * the page up. The caller needs to. 1493 */ 1494 } else { 1495 /* 1496 * If a write error occurs, reactivate page 1497 * so it doesn't clog the inactive list, 1498 * then finish the I/O. 1499 */ 1500 vm_page_dirty(m); 1501 vm_page_activate(m); 1502 vm_page_io_finish(m); 1503 } 1504 } else if (bp->b_iocmd == BIO_READ) { 1505 /* 1506 * For read success, clear dirty bits. Nobody should 1507 * have this page mapped but don't take any chances, 1508 * make sure the pmap modify bits are also cleared. 1509 * 1510 * NOTE: for reads, m->dirty will probably be 1511 * overridden by the original caller of getpages so 1512 * we cannot set them in order to free the underlying 1513 * swap in a low-swap situation. I don't think we'd 1514 * want to do that anyway, but it was an optimization 1515 * that existed in the old swapper for a time before 1516 * it got ripped out due to precisely this problem. 1517 * 1518 * If not the requested page then deactivate it. 1519 * 1520 * Note that the requested page, reqpage, is left 1521 * busied, but we still have to wake it up. The 1522 * other pages are released (unbusied) by 1523 * vm_page_wakeup(). We do not set reqpage's 1524 * valid bits here, it is up to the caller. 1525 */ 1526 pmap_clear_modify(m); 1527 m->valid = VM_PAGE_BITS_ALL; 1528 vm_page_undirty(m); 1529 1530 /* 1531 * We have to wake specifically requested pages 1532 * up too because we cleared PG_SWAPINPROG and 1533 * could be waiting for it in getpages. However, 1534 * be sure to not unbusy getpages specifically 1535 * requested page - getpages expects it to be 1536 * left busy. 1537 */ 1538 if (i != bp->b_pager.pg_reqpage) { 1539 vm_page_deactivate(m); 1540 vm_page_wakeup(m); 1541 } else { 1542 vm_page_flash(m); 1543 } 1544 } else { 1545 /* 1546 * For write success, clear the modify and dirty 1547 * status, then finish the I/O ( which decrements the 1548 * busy count and possibly wakes waiter's up ). 1549 */ 1550 pmap_clear_modify(m); 1551 vm_page_undirty(m); 1552 vm_page_io_finish(m); 1553 if (vm_page_count_severe()) 1554 vm_page_try_to_cache(m); 1555 } 1556 } 1557 vm_page_unlock_queues(); 1558 1559 /* 1560 * adjust pip. NOTE: the original parent may still have its own 1561 * pip refs on the object. 1562 */ 1563 if (object != NULL) { 1564 vm_object_pip_wakeupn(object, bp->b_npages); 1565 VM_OBJECT_UNLOCK(object); 1566 } 1567 1568 /* 1569 * release the physical I/O buffer 1570 */ 1571 relpbuf( 1572 bp, 1573 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount : 1574 ((bp->b_flags & B_ASYNC) ? 1575 &nsw_wcount_async : 1576 &nsw_wcount_sync 1577 ) 1578 ) 1579 ); 1580 splx(s); 1581} 1582 1583/* 1584 * swap_pager_isswapped: 1585 * 1586 * Return 1 if at least one page in the given object is paged 1587 * out to the given swap device. 1588 * 1589 * This routine may not block. 1590 */ 1591int 1592swap_pager_isswapped(vm_object_t object, struct swdevt *sp) 1593{ 1594 daddr_t index = 0; 1595 int bcount; 1596 int i; 1597 1598 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1599 for (bcount = 0; bcount < object->un_pager.swp.swp_bcount; bcount++) { 1600 struct swblock *swap; 1601 1602 mtx_lock(&swhash_mtx); 1603 if ((swap = *swp_pager_hash(object, index)) != NULL) { 1604 for (i = 0; i < SWAP_META_PAGES; ++i) { 1605 daddr_t v = swap->swb_pages[i]; 1606 if (v == SWAPBLK_NONE) 1607 continue; 1608 if (swp_pager_find_dev(v) == sp) { 1609 mtx_unlock(&swhash_mtx); 1610 return 1; 1611 } 1612 } 1613 } 1614 mtx_unlock(&swhash_mtx); 1615 index += SWAP_META_PAGES; 1616 if (index > 0x20000000) 1617 panic("swap_pager_isswapped: failed to locate all swap meta blocks"); 1618 } 1619 return 0; 1620} 1621 1622/* 1623 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in 1624 * 1625 * This routine dissociates the page at the given index within a 1626 * swap block from its backing store, paging it in if necessary. 1627 * If the page is paged in, it is placed in the inactive queue, 1628 * since it had its backing store ripped out from under it. 1629 * We also attempt to swap in all other pages in the swap block, 1630 * we only guarantee that the one at the specified index is 1631 * paged in. 1632 * 1633 * XXX - The code to page the whole block in doesn't work, so we 1634 * revert to the one-by-one behavior for now. Sigh. 1635 */ 1636static __inline void 1637swp_pager_force_pagein(struct swblock *swap, int idx) 1638{ 1639 vm_object_t object; 1640 vm_page_t m; 1641 vm_pindex_t pindex; 1642 1643 object = swap->swb_object; 1644 pindex = swap->swb_index; 1645 mtx_unlock(&swhash_mtx); 1646 1647 VM_OBJECT_LOCK(object); 1648 vm_object_pip_add(object, 1); 1649 m = vm_page_grab(object, pindex + idx, VM_ALLOC_NORMAL|VM_ALLOC_RETRY); 1650 if (m->valid == VM_PAGE_BITS_ALL) { 1651 vm_object_pip_subtract(object, 1); 1652 vm_page_lock_queues(); 1653 vm_page_activate(m); 1654 vm_page_dirty(m); 1655 vm_page_wakeup(m); 1656 vm_page_unlock_queues(); 1657 vm_pager_page_unswapped(m); 1658 VM_OBJECT_UNLOCK(object); 1659 return; 1660 } 1661 1662 if (swap_pager_getpages(object, &m, 1, 0) != 1663 VM_PAGER_OK) 1664 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/ 1665 vm_object_pip_subtract(object, 1); 1666 vm_page_lock_queues(); 1667 vm_page_dirty(m); 1668 vm_page_dontneed(m); 1669 vm_page_wakeup(m); 1670 vm_page_unlock_queues(); 1671 vm_pager_page_unswapped(m); 1672 VM_OBJECT_UNLOCK(object); 1673} 1674 1675 1676/* 1677 * swap_pager_swapoff: 1678 * 1679 * Page in all of the pages that have been paged out to the 1680 * given device. The corresponding blocks in the bitmap must be 1681 * marked as allocated and the device must be flagged SW_CLOSING. 1682 * There may be no processes swapped out to the device. 1683 * 1684 * The sw_used parameter points to the field in the swdev structure 1685 * that contains a count of the number of blocks still allocated 1686 * on the device. If we encounter objects with a nonzero pip count 1687 * in our scan, we use this number to determine if we're really done. 1688 * 1689 * This routine may block. 1690 */ 1691static void 1692swap_pager_swapoff(struct swdevt *sp, int *sw_used) 1693{ 1694 struct swblock **pswap; 1695 struct swblock *swap; 1696 vm_object_t waitobj; 1697 daddr_t v; 1698 int i, j; 1699 1700 GIANT_REQUIRED; 1701 1702full_rescan: 1703 waitobj = NULL; 1704 for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */ 1705restart: 1706 pswap = &swhash[i]; 1707 mtx_lock(&swhash_mtx); 1708 while ((swap = *pswap) != NULL) { 1709 for (j = 0; j < SWAP_META_PAGES; ++j) { 1710 v = swap->swb_pages[j]; 1711 if (v != SWAPBLK_NONE && 1712 swp_pager_find_dev(v) == sp) 1713 break; 1714 } 1715 if (j < SWAP_META_PAGES) { 1716 swp_pager_force_pagein(swap, j); 1717 goto restart; 1718 } else if (swap->swb_object->paging_in_progress) { 1719 if (!waitobj) 1720 waitobj = swap->swb_object; 1721 } 1722 pswap = &swap->swb_hnext; 1723 } 1724 mtx_unlock(&swhash_mtx); 1725 } 1726 if (waitobj && *sw_used) { 1727 /* 1728 * We wait on an arbitrary object to clock our rescans 1729 * to the rate of paging completion. 1730 */ 1731 VM_OBJECT_LOCK(waitobj); 1732 vm_object_pip_wait(waitobj, "swpoff"); 1733 VM_OBJECT_UNLOCK(waitobj); 1734 goto full_rescan; 1735 } 1736 if (*sw_used) 1737 panic("swapoff: failed to locate %d swap blocks", *sw_used); 1738} 1739 1740/************************************************************************ 1741 * SWAP META DATA * 1742 ************************************************************************ 1743 * 1744 * These routines manipulate the swap metadata stored in the 1745 * OBJT_SWAP object. All swp_*() routines must be called at 1746 * splvm() because swap can be freed up by the low level vm_page 1747 * code which might be called from interrupts beyond what splbio() covers. 1748 * 1749 * Swap metadata is implemented with a global hash and not directly 1750 * linked into the object. Instead the object simply contains 1751 * appropriate tracking counters. 1752 */ 1753 1754/* 1755 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1756 * 1757 * We first convert the object to a swap object if it is a default 1758 * object. 1759 * 1760 * The specified swapblk is added to the object's swap metadata. If 1761 * the swapblk is not valid, it is freed instead. Any previously 1762 * assigned swapblk is freed. 1763 * 1764 * This routine must be called at splvm(), except when used to convert 1765 * an OBJT_DEFAULT object into an OBJT_SWAP object. 1766 */ 1767static void 1768swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1769{ 1770 struct swblock *swap; 1771 struct swblock **pswap; 1772 int idx; 1773 1774 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1775 /* 1776 * Convert default object to swap object if necessary 1777 */ 1778 if (object->type != OBJT_SWAP) { 1779 object->type = OBJT_SWAP; 1780 object->un_pager.swp.swp_bcount = 0; 1781 1782 if (object->handle != NULL) { 1783 mtx_lock(&sw_alloc_mtx); 1784 TAILQ_INSERT_TAIL( 1785 NOBJLIST(object->handle), 1786 object, 1787 pager_object_list 1788 ); 1789 mtx_unlock(&sw_alloc_mtx); 1790 } 1791 } 1792 1793 /* 1794 * Locate hash entry. If not found create, but if we aren't adding 1795 * anything just return. If we run out of space in the map we wait 1796 * and, since the hash table may have changed, retry. 1797 */ 1798retry: 1799 mtx_lock(&swhash_mtx); 1800 pswap = swp_pager_hash(object, pindex); 1801 1802 if ((swap = *pswap) == NULL) { 1803 int i; 1804 1805 if (swapblk == SWAPBLK_NONE) 1806 goto done; 1807 1808 swap = *pswap = uma_zalloc(swap_zone, M_NOWAIT); 1809 if (swap == NULL) { 1810 mtx_unlock(&swhash_mtx); 1811 VM_OBJECT_UNLOCK(object); 1812 VM_WAIT; 1813 VM_OBJECT_LOCK(object); 1814 goto retry; 1815 } 1816 1817 swap->swb_hnext = NULL; 1818 swap->swb_object = object; 1819 swap->swb_index = pindex & ~(vm_pindex_t)SWAP_META_MASK; 1820 swap->swb_count = 0; 1821 1822 ++object->un_pager.swp.swp_bcount; 1823 1824 for (i = 0; i < SWAP_META_PAGES; ++i) 1825 swap->swb_pages[i] = SWAPBLK_NONE; 1826 } 1827 1828 /* 1829 * Delete prior contents of metadata 1830 */ 1831 idx = pindex & SWAP_META_MASK; 1832 1833 if (swap->swb_pages[idx] != SWAPBLK_NONE) { 1834 swp_pager_freeswapspace(swap->swb_pages[idx], 1); 1835 --swap->swb_count; 1836 } 1837 1838 /* 1839 * Enter block into metadata 1840 */ 1841 swap->swb_pages[idx] = swapblk; 1842 if (swapblk != SWAPBLK_NONE) 1843 ++swap->swb_count; 1844done: 1845 mtx_unlock(&swhash_mtx); 1846} 1847 1848/* 1849 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 1850 * 1851 * The requested range of blocks is freed, with any associated swap 1852 * returned to the swap bitmap. 1853 * 1854 * This routine will free swap metadata structures as they are cleaned 1855 * out. This routine does *NOT* operate on swap metadata associated 1856 * with resident pages. 1857 * 1858 * This routine must be called at splvm() 1859 */ 1860static void 1861swp_pager_meta_free(vm_object_t object, vm_pindex_t index, daddr_t count) 1862{ 1863 1864 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1865 if (object->type != OBJT_SWAP) 1866 return; 1867 1868 while (count > 0) { 1869 struct swblock **pswap; 1870 struct swblock *swap; 1871 1872 mtx_lock(&swhash_mtx); 1873 pswap = swp_pager_hash(object, index); 1874 1875 if ((swap = *pswap) != NULL) { 1876 daddr_t v = swap->swb_pages[index & SWAP_META_MASK]; 1877 1878 if (v != SWAPBLK_NONE) { 1879 swp_pager_freeswapspace(v, 1); 1880 swap->swb_pages[index & SWAP_META_MASK] = 1881 SWAPBLK_NONE; 1882 if (--swap->swb_count == 0) { 1883 *pswap = swap->swb_hnext; 1884 uma_zfree(swap_zone, swap); 1885 --object->un_pager.swp.swp_bcount; 1886 } 1887 } 1888 --count; 1889 ++index; 1890 } else { 1891 int n = SWAP_META_PAGES - (index & SWAP_META_MASK); 1892 count -= n; 1893 index += n; 1894 } 1895 mtx_unlock(&swhash_mtx); 1896 } 1897} 1898 1899/* 1900 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 1901 * 1902 * This routine locates and destroys all swap metadata associated with 1903 * an object. 1904 * 1905 * This routine must be called at splvm() 1906 */ 1907static void 1908swp_pager_meta_free_all(vm_object_t object) 1909{ 1910 daddr_t index = 0; 1911 1912 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1913 if (object->type != OBJT_SWAP) 1914 return; 1915 1916 while (object->un_pager.swp.swp_bcount) { 1917 struct swblock **pswap; 1918 struct swblock *swap; 1919 1920 mtx_lock(&swhash_mtx); 1921 pswap = swp_pager_hash(object, index); 1922 if ((swap = *pswap) != NULL) { 1923 int i; 1924 1925 for (i = 0; i < SWAP_META_PAGES; ++i) { 1926 daddr_t v = swap->swb_pages[i]; 1927 if (v != SWAPBLK_NONE) { 1928 --swap->swb_count; 1929 swp_pager_freeswapspace(v, 1); 1930 } 1931 } 1932 if (swap->swb_count != 0) 1933 panic("swap_pager_meta_free_all: swb_count != 0"); 1934 *pswap = swap->swb_hnext; 1935 uma_zfree(swap_zone, swap); 1936 --object->un_pager.swp.swp_bcount; 1937 } 1938 mtx_unlock(&swhash_mtx); 1939 index += SWAP_META_PAGES; 1940 if (index > 0x20000000) 1941 panic("swp_pager_meta_free_all: failed to locate all swap meta blocks"); 1942 } 1943} 1944 1945/* 1946 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. 1947 * 1948 * This routine is capable of looking up, popping, or freeing 1949 * swapblk assignments in the swap meta data or in the vm_page_t. 1950 * The routine typically returns the swapblk being looked-up, or popped, 1951 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block 1952 * was invalid. This routine will automatically free any invalid 1953 * meta-data swapblks. 1954 * 1955 * It is not possible to store invalid swapblks in the swap meta data 1956 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking. 1957 * 1958 * When acting on a busy resident page and paging is in progress, we 1959 * have to wait until paging is complete but otherwise can act on the 1960 * busy page. 1961 * 1962 * This routine must be called at splvm(). 1963 * 1964 * SWM_FREE remove and free swap block from metadata 1965 * SWM_POP remove from meta data but do not free.. pop it out 1966 */ 1967static daddr_t 1968swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags) 1969{ 1970 struct swblock **pswap; 1971 struct swblock *swap; 1972 daddr_t r1; 1973 int idx; 1974 1975 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1976 /* 1977 * The meta data only exists of the object is OBJT_SWAP 1978 * and even then might not be allocated yet. 1979 */ 1980 if (object->type != OBJT_SWAP) 1981 return (SWAPBLK_NONE); 1982 1983 r1 = SWAPBLK_NONE; 1984 mtx_lock(&swhash_mtx); 1985 pswap = swp_pager_hash(object, pindex); 1986 1987 if ((swap = *pswap) != NULL) { 1988 idx = pindex & SWAP_META_MASK; 1989 r1 = swap->swb_pages[idx]; 1990 1991 if (r1 != SWAPBLK_NONE) { 1992 if (flags & SWM_FREE) { 1993 swp_pager_freeswapspace(r1, 1); 1994 r1 = SWAPBLK_NONE; 1995 } 1996 if (flags & (SWM_FREE|SWM_POP)) { 1997 swap->swb_pages[idx] = SWAPBLK_NONE; 1998 if (--swap->swb_count == 0) { 1999 *pswap = swap->swb_hnext; 2000 uma_zfree(swap_zone, swap); 2001 --object->un_pager.swp.swp_bcount; 2002 } 2003 } 2004 } 2005 } 2006 mtx_unlock(&swhash_mtx); 2007 return (r1); 2008} 2009 2010/* 2011 * System call swapon(name) enables swapping on device name, 2012 * which must be in the swdevsw. Return EBUSY 2013 * if already swapping on this device. 2014 */ 2015#ifndef _SYS_SYSPROTO_H_ 2016struct swapon_args { 2017 char *name; 2018}; 2019#endif 2020 2021/* 2022 * MPSAFE 2023 */ 2024/* ARGSUSED */ 2025int 2026swapon(struct thread *td, struct swapon_args *uap) 2027{ 2028 struct vattr attr; 2029 struct vnode *vp; 2030 struct nameidata nd; 2031 int error; 2032 2033 mtx_lock(&Giant); 2034 error = suser(td); 2035 if (error) 2036 goto done2; 2037 2038 while (swdev_syscall_active) 2039 tsleep(&swdev_syscall_active, PUSER - 1, "swpon", 0); 2040 swdev_syscall_active = 1; 2041 2042 /* 2043 * Swap metadata may not fit in the KVM if we have physical 2044 * memory of >1GB. 2045 */ 2046 if (swap_zone == NULL) { 2047 error = ENOMEM; 2048 goto done; 2049 } 2050 2051 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, td); 2052 error = namei(&nd); 2053 if (error) 2054 goto done; 2055 2056 NDFREE(&nd, NDF_ONLY_PNBUF); 2057 vp = nd.ni_vp; 2058 2059 if (vn_isdisk(vp, &error)) { 2060 error = swapongeom(td, vp); 2061 } else if (vp->v_type == VREG && 2062 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2063 (error = VOP_GETATTR(vp, &attr, td->td_ucred, td)) == 0) { 2064 /* 2065 * Allow direct swapping to NFS regular files in the same 2066 * way that nfs_mountroot() sets up diskless swapping. 2067 */ 2068 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2069 } 2070 2071 if (error) 2072 vrele(vp); 2073done: 2074 swdev_syscall_active = 0; 2075 wakeup_one(&swdev_syscall_active); 2076done2: 2077 mtx_unlock(&Giant); 2078 return (error); 2079} 2080 2081static void
| 158 struct vnode *sw_vp; 159 void *sw_id; 160 swblk_t sw_first; 161 swblk_t sw_end; 162 struct blist *sw_blist; 163 TAILQ_ENTRY(swdevt) sw_list; 164 sw_strategy_t *sw_strategy; 165 sw_close_t *sw_close; 166}; 167 168#define SW_CLOSING 0x04 169 170struct swblock { 171 struct swblock *swb_hnext; 172 vm_object_t swb_object; 173 vm_pindex_t swb_index; 174 int swb_count; 175 daddr_t swb_pages[SWAP_META_PAGES]; 176}; 177 178static struct mtx sw_dev_mtx; 179static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 180static struct swdevt *swdevhd; /* Allocate from here next */ 181static int nswapdev; /* Number of swap devices */ 182int swap_pager_avail; 183static int swdev_syscall_active = 0; /* serialize swap(on|off) */ 184 185static void swapdev_strategy(struct buf *, struct swdevt *sw); 186 187#define SWM_FREE 0x02 /* free, period */ 188#define SWM_POP 0x04 /* pop out */ 189 190int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 191static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 192static int nsw_rcount; /* free read buffers */ 193static int nsw_wcount_sync; /* limit write buffers / synchronous */ 194static int nsw_wcount_async; /* limit write buffers / asynchronous */ 195static int nsw_wcount_async_max;/* assigned maximum */ 196static int nsw_cluster_max; /* maximum VOP I/O allowed */ 197 198static struct swblock **swhash; 199static int swhash_mask; 200static struct mtx swhash_mtx; 201 202static int swap_async_max = 4; /* maximum in-progress async I/O's */ 203static struct sx sw_alloc_sx; 204 205 206SYSCTL_INT(_vm, OID_AUTO, swap_async_max, 207 CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops"); 208 209/* 210 * "named" and "unnamed" anon region objects. Try to reduce the overhead 211 * of searching a named list by hashing it just a little. 212 */ 213 214#define NOBJLISTS 8 215 216#define NOBJLIST(handle) \ 217 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 218 219static struct mtx sw_alloc_mtx; /* protect list manipulation */ 220static struct pagerlst swap_pager_object_list[NOBJLISTS]; 221static uma_zone_t swap_zone; 222 223/* 224 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 225 * calls hooked from other parts of the VM system and do not appear here. 226 * (see vm/swap_pager.h). 227 */ 228static vm_object_t 229 swap_pager_alloc(void *handle, vm_ooffset_t size, 230 vm_prot_t prot, vm_ooffset_t offset); 231static void swap_pager_dealloc(vm_object_t object); 232static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int); 233static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 234static boolean_t 235 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 236static void swap_pager_init(void); 237static void swap_pager_unswapped(vm_page_t); 238static void swap_pager_swapoff(struct swdevt *sp, int *sw_used); 239 240struct pagerops swappagerops = { 241 .pgo_init = swap_pager_init, /* early system initialization of pager */ 242 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 243 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 244 .pgo_getpages = swap_pager_getpages, /* pagein */ 245 .pgo_putpages = swap_pager_putpages, /* pageout */ 246 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 247 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 248}; 249 250/* 251 * dmmax is in page-sized chunks with the new swap system. It was 252 * dev-bsized chunks in the old. dmmax is always a power of 2. 253 * 254 * swap_*() routines are externally accessible. swp_*() routines are 255 * internal. 256 */ 257static int dmmax; 258static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 259static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 260 261SYSCTL_INT(_vm, OID_AUTO, dmmax, 262 CTLFLAG_RD, &dmmax, 0, "Maximum size of a swap block"); 263 264static void swp_sizecheck(void); 265static void swp_pager_async_iodone(struct buf *bp); 266static int swapongeom(struct thread *, struct vnode *); 267static int swaponvp(struct thread *, struct vnode *, u_long); 268 269/* 270 * Swap bitmap functions 271 */ 272static void swp_pager_freeswapspace(daddr_t blk, int npages); 273static daddr_t swp_pager_getswapspace(int npages); 274 275/* 276 * Metadata functions 277 */ 278static struct swblock **swp_pager_hash(vm_object_t object, vm_pindex_t index); 279static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 280static void swp_pager_meta_free(vm_object_t, vm_pindex_t, daddr_t); 281static void swp_pager_meta_free_all(vm_object_t); 282static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 283 284/* 285 * SWP_SIZECHECK() - update swap_pager_full indication 286 * 287 * update the swap_pager_almost_full indication and warn when we are 288 * about to run out of swap space, using lowat/hiwat hysteresis. 289 * 290 * Clear swap_pager_full ( task killing ) indication when lowat is met. 291 * 292 * No restrictions on call 293 * This routine may not block. 294 * This routine must be called at splvm() 295 */ 296static void 297swp_sizecheck(void) 298{ 299 300 if (swap_pager_avail < nswap_lowat) { 301 if (swap_pager_almost_full == 0) { 302 printf("swap_pager: out of swap space\n"); 303 swap_pager_almost_full = 1; 304 } 305 } else { 306 swap_pager_full = 0; 307 if (swap_pager_avail > nswap_hiwat) 308 swap_pager_almost_full = 0; 309 } 310} 311 312/* 313 * SWP_PAGER_HASH() - hash swap meta data 314 * 315 * This is an helper function which hashes the swapblk given 316 * the object and page index. It returns a pointer to a pointer 317 * to the object, or a pointer to a NULL pointer if it could not 318 * find a swapblk. 319 * 320 * This routine must be called at splvm(). 321 */ 322static struct swblock ** 323swp_pager_hash(vm_object_t object, vm_pindex_t index) 324{ 325 struct swblock **pswap; 326 struct swblock *swap; 327 328 index &= ~(vm_pindex_t)SWAP_META_MASK; 329 pswap = &swhash[(index ^ (int)(intptr_t)object) & swhash_mask]; 330 while ((swap = *pswap) != NULL) { 331 if (swap->swb_object == object && 332 swap->swb_index == index 333 ) { 334 break; 335 } 336 pswap = &swap->swb_hnext; 337 } 338 return (pswap); 339} 340 341/* 342 * SWAP_PAGER_INIT() - initialize the swap pager! 343 * 344 * Expected to be started from system init. NOTE: This code is run 345 * before much else so be careful what you depend on. Most of the VM 346 * system has yet to be initialized at this point. 347 */ 348static void 349swap_pager_init(void) 350{ 351 /* 352 * Initialize object lists 353 */ 354 int i; 355 356 for (i = 0; i < NOBJLISTS; ++i) 357 TAILQ_INIT(&swap_pager_object_list[i]); 358 mtx_init(&sw_alloc_mtx, "swap_pager list", NULL, MTX_DEF); 359 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 360 361 /* 362 * Device Stripe, in PAGE_SIZE'd blocks 363 */ 364 dmmax = SWB_NPAGES * 2; 365} 366 367/* 368 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 369 * 370 * Expected to be started from pageout process once, prior to entering 371 * its main loop. 372 */ 373void 374swap_pager_swap_init(void) 375{ 376 int n, n2; 377 378 /* 379 * Number of in-transit swap bp operations. Don't 380 * exhaust the pbufs completely. Make sure we 381 * initialize workable values (0 will work for hysteresis 382 * but it isn't very efficient). 383 * 384 * The nsw_cluster_max is constrained by the bp->b_pages[] 385 * array (MAXPHYS/PAGE_SIZE) and our locally defined 386 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 387 * constrained by the swap device interleave stripe size. 388 * 389 * Currently we hardwire nsw_wcount_async to 4. This limit is 390 * designed to prevent other I/O from having high latencies due to 391 * our pageout I/O. The value 4 works well for one or two active swap 392 * devices but is probably a little low if you have more. Even so, 393 * a higher value would probably generate only a limited improvement 394 * with three or four active swap devices since the system does not 395 * typically have to pageout at extreme bandwidths. We will want 396 * at least 2 per swap devices, and 4 is a pretty good value if you 397 * have one NFS swap device due to the command/ack latency over NFS. 398 * So it all works out pretty well. 399 */ 400 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER); 401 402 mtx_lock(&pbuf_mtx); 403 nsw_rcount = (nswbuf + 1) / 2; 404 nsw_wcount_sync = (nswbuf + 3) / 4; 405 nsw_wcount_async = 4; 406 nsw_wcount_async_max = nsw_wcount_async; 407 mtx_unlock(&pbuf_mtx); 408 409 /* 410 * Initialize our zone. Right now I'm just guessing on the number 411 * we need based on the number of pages in the system. Each swblock 412 * can hold 16 pages, so this is probably overkill. This reservation 413 * is typically limited to around 32MB by default. 414 */ 415 n = cnt.v_page_count / 2; 416 if (maxswzone && n > maxswzone / sizeof(struct swblock)) 417 n = maxswzone / sizeof(struct swblock); 418 n2 = n; 419 swap_zone = uma_zcreate("SWAPMETA", sizeof(struct swblock), NULL, NULL, 420 NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE | UMA_ZONE_VM); 421 do { 422 if (uma_zone_set_obj(swap_zone, NULL, n)) 423 break; 424 /* 425 * if the allocation failed, try a zone two thirds the 426 * size of the previous attempt. 427 */ 428 n -= ((n + 2) / 3); 429 } while (n > 0); 430 if (swap_zone == NULL) 431 panic("failed to create swap_zone."); 432 if (n2 != n) 433 printf("Swap zone entries reduced from %d to %d.\n", n2, n); 434 n2 = n; 435 436 /* 437 * Initialize our meta-data hash table. The swapper does not need to 438 * be quite as efficient as the VM system, so we do not use an 439 * oversized hash table. 440 * 441 * n: size of hash table, must be power of 2 442 * swhash_mask: hash table index mask 443 */ 444 for (n = 1; n < n2 / 8; n *= 2) 445 ; 446 swhash = malloc(sizeof(struct swblock *) * n, M_VMPGDATA, M_WAITOK | M_ZERO); 447 swhash_mask = n - 1; 448 mtx_init(&swhash_mtx, "swap_pager swhash", NULL, MTX_DEF); 449} 450 451/* 452 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 453 * its metadata structures. 454 * 455 * This routine is called from the mmap and fork code to create a new 456 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object 457 * and then converting it with swp_pager_meta_build(). 458 * 459 * This routine may block in vm_object_allocate() and create a named 460 * object lookup race, so we must interlock. We must also run at 461 * splvm() for the object lookup to handle races with interrupts, but 462 * we do not have to maintain splvm() in between the lookup and the 463 * add because (I believe) it is not possible to attempt to create 464 * a new swap object w/handle when a default object with that handle 465 * already exists. 466 * 467 * MPSAFE 468 */ 469static vm_object_t 470swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 471 vm_ooffset_t offset) 472{ 473 vm_object_t object; 474 vm_pindex_t pindex; 475 476 pindex = OFF_TO_IDX(offset + PAGE_MASK + size); 477 478 if (handle) { 479 mtx_lock(&Giant); 480 /* 481 * Reference existing named region or allocate new one. There 482 * should not be a race here against swp_pager_meta_build() 483 * as called from vm_page_remove() in regards to the lookup 484 * of the handle. 485 */ 486 sx_xlock(&sw_alloc_sx); 487 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 488 489 if (object != NULL) { 490 vm_object_reference(object); 491 } else { 492 object = vm_object_allocate(OBJT_DEFAULT, pindex); 493 object->handle = handle; 494 495 VM_OBJECT_LOCK(object); 496 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 497 VM_OBJECT_UNLOCK(object); 498 } 499 sx_xunlock(&sw_alloc_sx); 500 mtx_unlock(&Giant); 501 } else { 502 object = vm_object_allocate(OBJT_DEFAULT, pindex); 503 504 VM_OBJECT_LOCK(object); 505 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 506 VM_OBJECT_UNLOCK(object); 507 } 508 return (object); 509} 510 511/* 512 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 513 * 514 * The swap backing for the object is destroyed. The code is 515 * designed such that we can reinstantiate it later, but this 516 * routine is typically called only when the entire object is 517 * about to be destroyed. 518 * 519 * This routine may block, but no longer does. 520 * 521 * The object must be locked or unreferenceable. 522 */ 523static void 524swap_pager_dealloc(vm_object_t object) 525{ 526 int s; 527 528 /* 529 * Remove from list right away so lookups will fail if we block for 530 * pageout completion. 531 */ 532 if (object->handle != NULL) { 533 mtx_lock(&sw_alloc_mtx); 534 TAILQ_REMOVE(NOBJLIST(object->handle), object, pager_object_list); 535 mtx_unlock(&sw_alloc_mtx); 536 } 537 538 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 539 vm_object_pip_wait(object, "swpdea"); 540 541 /* 542 * Free all remaining metadata. We only bother to free it from 543 * the swap meta data. We do not attempt to free swapblk's still 544 * associated with vm_page_t's for this object. We do not care 545 * if paging is still in progress on some objects. 546 */ 547 s = splvm(); 548 swp_pager_meta_free_all(object); 549 splx(s); 550} 551 552/************************************************************************ 553 * SWAP PAGER BITMAP ROUTINES * 554 ************************************************************************/ 555 556/* 557 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 558 * 559 * Allocate swap for the requested number of pages. The starting 560 * swap block number (a page index) is returned or SWAPBLK_NONE 561 * if the allocation failed. 562 * 563 * Also has the side effect of advising that somebody made a mistake 564 * when they configured swap and didn't configure enough. 565 * 566 * Must be called at splvm() to avoid races with bitmap frees from 567 * vm_page_remove() aka swap_pager_page_removed(). 568 * 569 * This routine may not block 570 * This routine must be called at splvm(). 571 * 572 * We allocate in round-robin fashion from the configured devices. 573 */ 574static daddr_t 575swp_pager_getswapspace(int npages) 576{ 577 daddr_t blk; 578 struct swdevt *sp; 579 int i; 580 581 blk = SWAPBLK_NONE; 582 mtx_lock(&sw_dev_mtx); 583 sp = swdevhd; 584 for (i = 0; i < nswapdev; i++) { 585 if (sp == NULL) 586 sp = TAILQ_FIRST(&swtailq); 587 if (!(sp->sw_flags & SW_CLOSING)) { 588 blk = blist_alloc(sp->sw_blist, npages); 589 if (blk != SWAPBLK_NONE) { 590 blk += sp->sw_first; 591 sp->sw_used += npages; 592 swap_pager_avail -= npages; 593 swp_sizecheck(); 594 swdevhd = TAILQ_NEXT(sp, sw_list); 595 goto done; 596 } 597 } 598 sp = TAILQ_NEXT(sp, sw_list); 599 } 600 if (swap_pager_full != 2) { 601 printf("swap_pager_getswapspace(%d): failed\n", npages); 602 swap_pager_full = 2; 603 swap_pager_almost_full = 1; 604 } 605 swdevhd = NULL; 606done: 607 mtx_unlock(&sw_dev_mtx); 608 return (blk); 609} 610 611static struct swdevt * 612swp_pager_find_dev(daddr_t blk) 613{ 614 struct swdevt *sp; 615 616 mtx_lock(&sw_dev_mtx); 617 TAILQ_FOREACH(sp, &swtailq, sw_list) { 618 if (blk >= sp->sw_first && blk < sp->sw_end) { 619 mtx_unlock(&sw_dev_mtx); 620 return (sp); 621 } 622 } 623 panic("Swapdev not found"); 624} 625 626static void 627swp_pager_strategy(struct buf *bp) 628{ 629 struct swdevt *sp; 630 631 mtx_lock(&sw_dev_mtx); 632 TAILQ_FOREACH(sp, &swtailq, sw_list) { 633 if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) { 634 mtx_unlock(&sw_dev_mtx); 635 sp->sw_strategy(bp, sp); 636 return; 637 } 638 } 639 panic("Swapdev not found"); 640} 641 642 643/* 644 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 645 * 646 * This routine returns the specified swap blocks back to the bitmap. 647 * 648 * Note: This routine may not block (it could in the old swap code), 649 * and through the use of the new blist routines it does not block. 650 * 651 * We must be called at splvm() to avoid races with bitmap frees from 652 * vm_page_remove() aka swap_pager_page_removed(). 653 * 654 * This routine may not block 655 * This routine must be called at splvm(). 656 */ 657static void 658swp_pager_freeswapspace(daddr_t blk, int npages) 659{ 660 struct swdevt *sp; 661 662 mtx_lock(&sw_dev_mtx); 663 TAILQ_FOREACH(sp, &swtailq, sw_list) { 664 if (blk >= sp->sw_first && blk < sp->sw_end) { 665 sp->sw_used -= npages; 666 /* 667 * If we are attempting to stop swapping on 668 * this device, we don't want to mark any 669 * blocks free lest they be reused. 670 */ 671 if ((sp->sw_flags & SW_CLOSING) == 0) { 672 blist_free(sp->sw_blist, blk - sp->sw_first, 673 npages); 674 swap_pager_avail += npages; 675 swp_sizecheck(); 676 } 677 mtx_unlock(&sw_dev_mtx); 678 return; 679 } 680 } 681 panic("Swapdev not found"); 682} 683 684/* 685 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 686 * range within an object. 687 * 688 * This is a globally accessible routine. 689 * 690 * This routine removes swapblk assignments from swap metadata. 691 * 692 * The external callers of this routine typically have already destroyed 693 * or renamed vm_page_t's associated with this range in the object so 694 * we should be ok. 695 * 696 * This routine may be called at any spl. We up our spl to splvm temporarily 697 * in order to perform the metadata removal. 698 */ 699void 700swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 701{ 702 int s = splvm(); 703 704 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 705 swp_pager_meta_free(object, start, size); 706 splx(s); 707} 708 709/* 710 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 711 * 712 * Assigns swap blocks to the specified range within the object. The 713 * swap blocks are not zerod. Any previous swap assignment is destroyed. 714 * 715 * Returns 0 on success, -1 on failure. 716 */ 717int 718swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 719{ 720 int s; 721 int n = 0; 722 daddr_t blk = SWAPBLK_NONE; 723 vm_pindex_t beg = start; /* save start index */ 724 725 s = splvm(); 726 VM_OBJECT_LOCK(object); 727 while (size) { 728 if (n == 0) { 729 n = BLIST_MAX_ALLOC; 730 while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) { 731 n >>= 1; 732 if (n == 0) { 733 swp_pager_meta_free(object, beg, start - beg); 734 VM_OBJECT_UNLOCK(object); 735 splx(s); 736 return (-1); 737 } 738 } 739 } 740 swp_pager_meta_build(object, start, blk); 741 --size; 742 ++start; 743 ++blk; 744 --n; 745 } 746 swp_pager_meta_free(object, start, n); 747 VM_OBJECT_UNLOCK(object); 748 splx(s); 749 return (0); 750} 751 752/* 753 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 754 * and destroy the source. 755 * 756 * Copy any valid swapblks from the source to the destination. In 757 * cases where both the source and destination have a valid swapblk, 758 * we keep the destination's. 759 * 760 * This routine is allowed to block. It may block allocating metadata 761 * indirectly through swp_pager_meta_build() or if paging is still in 762 * progress on the source. 763 * 764 * This routine can be called at any spl 765 * 766 * XXX vm_page_collapse() kinda expects us not to block because we 767 * supposedly do not need to allocate memory, but for the moment we 768 * *may* have to get a little memory from the zone allocator, but 769 * it is taken from the interrupt memory. We should be ok. 770 * 771 * The source object contains no vm_page_t's (which is just as well) 772 * 773 * The source object is of type OBJT_SWAP. 774 * 775 * The source and destination objects must be locked or 776 * inaccessible (XXX are they ?) 777 */ 778void 779swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 780 vm_pindex_t offset, int destroysource) 781{ 782 vm_pindex_t i; 783 int s; 784 785 VM_OBJECT_LOCK_ASSERT(srcobject, MA_OWNED); 786 VM_OBJECT_LOCK_ASSERT(dstobject, MA_OWNED); 787 788 s = splvm(); 789 /* 790 * If destroysource is set, we remove the source object from the 791 * swap_pager internal queue now. 792 */ 793 if (destroysource) { 794 if (srcobject->handle != NULL) { 795 mtx_lock(&sw_alloc_mtx); 796 TAILQ_REMOVE( 797 NOBJLIST(srcobject->handle), 798 srcobject, 799 pager_object_list 800 ); 801 mtx_unlock(&sw_alloc_mtx); 802 } 803 } 804 805 /* 806 * transfer source to destination. 807 */ 808 for (i = 0; i < dstobject->size; ++i) { 809 daddr_t dstaddr; 810 811 /* 812 * Locate (without changing) the swapblk on the destination, 813 * unless it is invalid in which case free it silently, or 814 * if the destination is a resident page, in which case the 815 * source is thrown away. 816 */ 817 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 818 819 if (dstaddr == SWAPBLK_NONE) { 820 /* 821 * Destination has no swapblk and is not resident, 822 * copy source. 823 */ 824 daddr_t srcaddr; 825 826 srcaddr = swp_pager_meta_ctl( 827 srcobject, 828 i + offset, 829 SWM_POP 830 ); 831 832 if (srcaddr != SWAPBLK_NONE) { 833 /* 834 * swp_pager_meta_build() can sleep. 835 */ 836 vm_object_pip_add(srcobject, 1); 837 VM_OBJECT_UNLOCK(srcobject); 838 vm_object_pip_add(dstobject, 1); 839 swp_pager_meta_build(dstobject, i, srcaddr); 840 vm_object_pip_wakeup(dstobject); 841 VM_OBJECT_LOCK(srcobject); 842 vm_object_pip_wakeup(srcobject); 843 } 844 } else { 845 /* 846 * Destination has valid swapblk or it is represented 847 * by a resident page. We destroy the sourceblock. 848 */ 849 850 swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE); 851 } 852 } 853 854 /* 855 * Free left over swap blocks in source. 856 * 857 * We have to revert the type to OBJT_DEFAULT so we do not accidently 858 * double-remove the object from the swap queues. 859 */ 860 if (destroysource) { 861 swp_pager_meta_free_all(srcobject); 862 /* 863 * Reverting the type is not necessary, the caller is going 864 * to destroy srcobject directly, but I'm doing it here 865 * for consistency since we've removed the object from its 866 * queues. 867 */ 868 srcobject->type = OBJT_DEFAULT; 869 } 870 splx(s); 871} 872 873/* 874 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 875 * the requested page. 876 * 877 * We determine whether good backing store exists for the requested 878 * page and return TRUE if it does, FALSE if it doesn't. 879 * 880 * If TRUE, we also try to determine how much valid, contiguous backing 881 * store exists before and after the requested page within a reasonable 882 * distance. We do not try to restrict it to the swap device stripe 883 * (that is handled in getpages/putpages). It probably isn't worth 884 * doing here. 885 */ 886static boolean_t 887swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after) 888{ 889 daddr_t blk0; 890 int s; 891 892 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 893 /* 894 * do we have good backing store at the requested index ? 895 */ 896 s = splvm(); 897 blk0 = swp_pager_meta_ctl(object, pindex, 0); 898 899 if (blk0 == SWAPBLK_NONE) { 900 splx(s); 901 if (before) 902 *before = 0; 903 if (after) 904 *after = 0; 905 return (FALSE); 906 } 907 908 /* 909 * find backwards-looking contiguous good backing store 910 */ 911 if (before != NULL) { 912 int i; 913 914 for (i = 1; i < (SWB_NPAGES/2); ++i) { 915 daddr_t blk; 916 917 if (i > pindex) 918 break; 919 blk = swp_pager_meta_ctl(object, pindex - i, 0); 920 if (blk != blk0 - i) 921 break; 922 } 923 *before = (i - 1); 924 } 925 926 /* 927 * find forward-looking contiguous good backing store 928 */ 929 if (after != NULL) { 930 int i; 931 932 for (i = 1; i < (SWB_NPAGES/2); ++i) { 933 daddr_t blk; 934 935 blk = swp_pager_meta_ctl(object, pindex + i, 0); 936 if (blk != blk0 + i) 937 break; 938 } 939 *after = (i - 1); 940 } 941 splx(s); 942 return (TRUE); 943} 944 945/* 946 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 947 * 948 * This removes any associated swap backing store, whether valid or 949 * not, from the page. 950 * 951 * This routine is typically called when a page is made dirty, at 952 * which point any associated swap can be freed. MADV_FREE also 953 * calls us in a special-case situation 954 * 955 * NOTE!!! If the page is clean and the swap was valid, the caller 956 * should make the page dirty before calling this routine. This routine 957 * does NOT change the m->dirty status of the page. Also: MADV_FREE 958 * depends on it. 959 * 960 * This routine may not block 961 * This routine must be called at splvm() 962 */ 963static void 964swap_pager_unswapped(vm_page_t m) 965{ 966 967 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 968 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); 969} 970 971/* 972 * SWAP_PAGER_GETPAGES() - bring pages in from swap 973 * 974 * Attempt to retrieve (m, count) pages from backing store, but make 975 * sure we retrieve at least m[reqpage]. We try to load in as large 976 * a chunk surrounding m[reqpage] as is contiguous in swap and which 977 * belongs to the same object. 978 * 979 * The code is designed for asynchronous operation and 980 * immediate-notification of 'reqpage' but tends not to be 981 * used that way. Please do not optimize-out this algorithmic 982 * feature, I intend to improve on it in the future. 983 * 984 * The parent has a single vm_object_pip_add() reference prior to 985 * calling us and we should return with the same. 986 * 987 * The parent has BUSY'd the pages. We should return with 'm' 988 * left busy, but the others adjusted. 989 */ 990static int 991swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage) 992{ 993 struct buf *bp; 994 vm_page_t mreq; 995 int s; 996 int i; 997 int j; 998 daddr_t blk; 999 1000 mreq = m[reqpage]; 1001 1002 KASSERT(mreq->object == object, 1003 ("swap_pager_getpages: object mismatch %p/%p", 1004 object, mreq->object)); 1005 1006 /* 1007 * Calculate range to retrieve. The pages have already been assigned 1008 * their swapblks. We require a *contiguous* range but we know it to 1009 * not span devices. If we do not supply it, bad things 1010 * happen. Note that blk, iblk & jblk can be SWAPBLK_NONE, but the 1011 * loops are set up such that the case(s) are handled implicitly. 1012 * 1013 * The swp_*() calls must be made at splvm(). vm_page_free() does 1014 * not need to be, but it will go a little faster if it is. 1015 */ 1016 s = splvm(); 1017 blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0); 1018 1019 for (i = reqpage - 1; i >= 0; --i) { 1020 daddr_t iblk; 1021 1022 iblk = swp_pager_meta_ctl(m[i]->object, m[i]->pindex, 0); 1023 if (blk != iblk + (reqpage - i)) 1024 break; 1025 } 1026 ++i; 1027 1028 for (j = reqpage + 1; j < count; ++j) { 1029 daddr_t jblk; 1030 1031 jblk = swp_pager_meta_ctl(m[j]->object, m[j]->pindex, 0); 1032 if (blk != jblk - (j - reqpage)) 1033 break; 1034 } 1035 1036 /* 1037 * free pages outside our collection range. Note: we never free 1038 * mreq, it must remain busy throughout. 1039 */ 1040 vm_page_lock_queues(); 1041 { 1042 int k; 1043 1044 for (k = 0; k < i; ++k) 1045 vm_page_free(m[k]); 1046 for (k = j; k < count; ++k) 1047 vm_page_free(m[k]); 1048 } 1049 vm_page_unlock_queues(); 1050 splx(s); 1051 1052 1053 /* 1054 * Return VM_PAGER_FAIL if we have nothing to do. Return mreq 1055 * still busy, but the others unbusied. 1056 */ 1057 if (blk == SWAPBLK_NONE) 1058 return (VM_PAGER_FAIL); 1059 1060 /* 1061 * Getpbuf() can sleep. 1062 */ 1063 VM_OBJECT_UNLOCK(object); 1064 /* 1065 * Get a swap buffer header to perform the IO 1066 */ 1067 bp = getpbuf(&nsw_rcount); 1068 bp->b_flags |= B_PAGING; 1069 1070 /* 1071 * map our page(s) into kva for input 1072 */ 1073 pmap_qenter((vm_offset_t)bp->b_data, m + i, j - i); 1074 1075 bp->b_iocmd = BIO_READ; 1076 bp->b_iodone = swp_pager_async_iodone; 1077 bp->b_rcred = crhold(thread0.td_ucred); 1078 bp->b_wcred = crhold(thread0.td_ucred); 1079 bp->b_blkno = blk - (reqpage - i); 1080 bp->b_bcount = PAGE_SIZE * (j - i); 1081 bp->b_bufsize = PAGE_SIZE * (j - i); 1082 bp->b_pager.pg_reqpage = reqpage - i; 1083 1084 VM_OBJECT_LOCK(object); 1085 vm_page_lock_queues(); 1086 { 1087 int k; 1088 1089 for (k = i; k < j; ++k) { 1090 bp->b_pages[k - i] = m[k]; 1091 vm_page_flag_set(m[k], PG_SWAPINPROG); 1092 } 1093 } 1094 vm_page_unlock_queues(); 1095 VM_OBJECT_UNLOCK(object); 1096 bp->b_npages = j - i; 1097 1098 cnt.v_swapin++; 1099 cnt.v_swappgsin += bp->b_npages; 1100 1101 /* 1102 * We still hold the lock on mreq, and our automatic completion routine 1103 * does not remove it. 1104 */ 1105 VM_OBJECT_LOCK(mreq->object); 1106 vm_object_pip_add(mreq->object, bp->b_npages); 1107 VM_OBJECT_UNLOCK(mreq->object); 1108 1109 /* 1110 * perform the I/O. NOTE!!! bp cannot be considered valid after 1111 * this point because we automatically release it on completion. 1112 * Instead, we look at the one page we are interested in which we 1113 * still hold a lock on even through the I/O completion. 1114 * 1115 * The other pages in our m[] array are also released on completion, 1116 * so we cannot assume they are valid anymore either. 1117 * 1118 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1119 */ 1120 BUF_KERNPROC(bp); 1121 swp_pager_strategy(bp); 1122 1123 /* 1124 * wait for the page we want to complete. PG_SWAPINPROG is always 1125 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1126 * is set in the meta-data. 1127 */ 1128 s = splvm(); 1129 vm_page_lock_queues(); 1130 while ((mreq->flags & PG_SWAPINPROG) != 0) { 1131 vm_page_flag_set(mreq, PG_WANTED | PG_REFERENCED); 1132 cnt.v_intrans++; 1133 if (msleep(mreq, &vm_page_queue_mtx, PSWP, "swread", hz*20)) { 1134 printf( 1135 "swap_pager: indefinite wait buffer: device:" 1136 " %s, blkno: %ld, size: %ld\n", 1137 devtoname(bp->b_dev), (long)bp->b_blkno, 1138 bp->b_bcount 1139 ); 1140 } 1141 } 1142 vm_page_unlock_queues(); 1143 splx(s); 1144 1145 VM_OBJECT_LOCK(mreq->object); 1146 /* 1147 * mreq is left busied after completion, but all the other pages 1148 * are freed. If we had an unrecoverable read error the page will 1149 * not be valid. 1150 */ 1151 if (mreq->valid != VM_PAGE_BITS_ALL) { 1152 return (VM_PAGER_ERROR); 1153 } else { 1154 return (VM_PAGER_OK); 1155 } 1156 1157 /* 1158 * A final note: in a low swap situation, we cannot deallocate swap 1159 * and mark a page dirty here because the caller is likely to mark 1160 * the page clean when we return, causing the page to possibly revert 1161 * to all-zero's later. 1162 */ 1163} 1164 1165/* 1166 * swap_pager_putpages: 1167 * 1168 * Assign swap (if necessary) and initiate I/O on the specified pages. 1169 * 1170 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1171 * are automatically converted to SWAP objects. 1172 * 1173 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1174 * vm_page reservation system coupled with properly written VFS devices 1175 * should ensure that no low-memory deadlock occurs. This is an area 1176 * which needs work. 1177 * 1178 * The parent has N vm_object_pip_add() references prior to 1179 * calling us and will remove references for rtvals[] that are 1180 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1181 * completion. 1182 * 1183 * The parent has soft-busy'd the pages it passes us and will unbusy 1184 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1185 * We need to unbusy the rest on I/O completion. 1186 */ 1187void 1188swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1189 boolean_t sync, int *rtvals) 1190{ 1191 int i; 1192 int n = 0; 1193 1194 GIANT_REQUIRED; 1195 if (count && m[0]->object != object) { 1196 panic("swap_pager_getpages: object mismatch %p/%p", 1197 object, 1198 m[0]->object 1199 ); 1200 } 1201 1202 /* 1203 * Step 1 1204 * 1205 * Turn object into OBJT_SWAP 1206 * check for bogus sysops 1207 * force sync if not pageout process 1208 */ 1209 if (object->type != OBJT_SWAP) 1210 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1211 VM_OBJECT_UNLOCK(object); 1212 1213 if (curproc != pageproc) 1214 sync = TRUE; 1215 1216 /* 1217 * Step 2 1218 * 1219 * Update nsw parameters from swap_async_max sysctl values. 1220 * Do not let the sysop crash the machine with bogus numbers. 1221 */ 1222 mtx_lock(&pbuf_mtx); 1223 if (swap_async_max != nsw_wcount_async_max) { 1224 int n; 1225 int s; 1226 1227 /* 1228 * limit range 1229 */ 1230 if ((n = swap_async_max) > nswbuf / 2) 1231 n = nswbuf / 2; 1232 if (n < 1) 1233 n = 1; 1234 swap_async_max = n; 1235 1236 /* 1237 * Adjust difference ( if possible ). If the current async 1238 * count is too low, we may not be able to make the adjustment 1239 * at this time. 1240 */ 1241 s = splvm(); 1242 n -= nsw_wcount_async_max; 1243 if (nsw_wcount_async + n >= 0) { 1244 nsw_wcount_async += n; 1245 nsw_wcount_async_max += n; 1246 wakeup(&nsw_wcount_async); 1247 } 1248 splx(s); 1249 } 1250 mtx_unlock(&pbuf_mtx); 1251 1252 /* 1253 * Step 3 1254 * 1255 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1256 * The page is left dirty until the pageout operation completes 1257 * successfully. 1258 */ 1259 for (i = 0; i < count; i += n) { 1260 int s; 1261 int j; 1262 struct buf *bp; 1263 daddr_t blk; 1264 1265 /* 1266 * Maximum I/O size is limited by a number of factors. 1267 */ 1268 n = min(BLIST_MAX_ALLOC, count - i); 1269 n = min(n, nsw_cluster_max); 1270 1271 s = splvm(); 1272 1273 /* 1274 * Get biggest block of swap we can. If we fail, fall 1275 * back and try to allocate a smaller block. Don't go 1276 * overboard trying to allocate space if it would overly 1277 * fragment swap. 1278 */ 1279 while ( 1280 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE && 1281 n > 4 1282 ) { 1283 n >>= 1; 1284 } 1285 if (blk == SWAPBLK_NONE) { 1286 for (j = 0; j < n; ++j) 1287 rtvals[i+j] = VM_PAGER_FAIL; 1288 splx(s); 1289 continue; 1290 } 1291 1292 /* 1293 * All I/O parameters have been satisfied, build the I/O 1294 * request and assign the swap space. 1295 */ 1296 if (sync == TRUE) { 1297 bp = getpbuf(&nsw_wcount_sync); 1298 } else { 1299 bp = getpbuf(&nsw_wcount_async); 1300 bp->b_flags = B_ASYNC; 1301 } 1302 bp->b_flags |= B_PAGING; 1303 bp->b_iocmd = BIO_WRITE; 1304 1305 pmap_qenter((vm_offset_t)bp->b_data, &m[i], n); 1306 1307 bp->b_rcred = crhold(thread0.td_ucred); 1308 bp->b_wcred = crhold(thread0.td_ucred); 1309 bp->b_bcount = PAGE_SIZE * n; 1310 bp->b_bufsize = PAGE_SIZE * n; 1311 bp->b_blkno = blk; 1312 1313 VM_OBJECT_LOCK(object); 1314 for (j = 0; j < n; ++j) { 1315 vm_page_t mreq = m[i+j]; 1316 1317 swp_pager_meta_build( 1318 mreq->object, 1319 mreq->pindex, 1320 blk + j 1321 ); 1322 vm_page_dirty(mreq); 1323 rtvals[i+j] = VM_PAGER_OK; 1324 1325 vm_page_lock_queues(); 1326 vm_page_flag_set(mreq, PG_SWAPINPROG); 1327 vm_page_unlock_queues(); 1328 bp->b_pages[j] = mreq; 1329 } 1330 VM_OBJECT_UNLOCK(object); 1331 bp->b_npages = n; 1332 /* 1333 * Must set dirty range for NFS to work. 1334 */ 1335 bp->b_dirtyoff = 0; 1336 bp->b_dirtyend = bp->b_bcount; 1337 1338 cnt.v_swapout++; 1339 cnt.v_swappgsout += bp->b_npages; 1340 1341 splx(s); 1342 1343 /* 1344 * asynchronous 1345 * 1346 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1347 */ 1348 if (sync == FALSE) { 1349 bp->b_iodone = swp_pager_async_iodone; 1350 BUF_KERNPROC(bp); 1351 swp_pager_strategy(bp); 1352 1353 for (j = 0; j < n; ++j) 1354 rtvals[i+j] = VM_PAGER_PEND; 1355 /* restart outter loop */ 1356 continue; 1357 } 1358 1359 /* 1360 * synchronous 1361 * 1362 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1363 */ 1364 bp->b_iodone = bdone; 1365 swp_pager_strategy(bp); 1366 1367 /* 1368 * Wait for the sync I/O to complete, then update rtvals. 1369 * We just set the rtvals[] to VM_PAGER_PEND so we can call 1370 * our async completion routine at the end, thus avoiding a 1371 * double-free. 1372 */ 1373 s = splbio(); 1374 bwait(bp, PVM, "swwrt"); 1375 for (j = 0; j < n; ++j) 1376 rtvals[i+j] = VM_PAGER_PEND; 1377 /* 1378 * Now that we are through with the bp, we can call the 1379 * normal async completion, which frees everything up. 1380 */ 1381 swp_pager_async_iodone(bp); 1382 splx(s); 1383 } 1384 VM_OBJECT_LOCK(object); 1385} 1386 1387/* 1388 * swp_pager_async_iodone: 1389 * 1390 * Completion routine for asynchronous reads and writes from/to swap. 1391 * Also called manually by synchronous code to finish up a bp. 1392 * 1393 * For READ operations, the pages are PG_BUSY'd. For WRITE operations, 1394 * the pages are vm_page_t->busy'd. For READ operations, we PG_BUSY 1395 * unbusy all pages except the 'main' request page. For WRITE 1396 * operations, we vm_page_t->busy'd unbusy all pages ( we can do this 1397 * because we marked them all VM_PAGER_PEND on return from putpages ). 1398 * 1399 * This routine may not block. 1400 * This routine is called at splbio() or better 1401 * 1402 * We up ourselves to splvm() as required for various vm_page related 1403 * calls. 1404 */ 1405static void 1406swp_pager_async_iodone(struct buf *bp) 1407{ 1408 int s; 1409 int i; 1410 vm_object_t object = NULL; 1411 1412 bp->b_flags |= B_DONE; 1413 1414 /* 1415 * report error 1416 */ 1417 if (bp->b_ioflags & BIO_ERROR) { 1418 printf( 1419 "swap_pager: I/O error - %s failed; blkno %ld," 1420 "size %ld, error %d\n", 1421 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1422 (long)bp->b_blkno, 1423 (long)bp->b_bcount, 1424 bp->b_error 1425 ); 1426 } 1427 1428 /* 1429 * set object, raise to splvm(). 1430 */ 1431 s = splvm(); 1432 1433 /* 1434 * remove the mapping for kernel virtual 1435 */ 1436 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1437 1438 if (bp->b_npages) { 1439 object = bp->b_pages[0]->object; 1440 VM_OBJECT_LOCK(object); 1441 } 1442 vm_page_lock_queues(); 1443 /* 1444 * cleanup pages. If an error occurs writing to swap, we are in 1445 * very serious trouble. If it happens to be a disk error, though, 1446 * we may be able to recover by reassigning the swap later on. So 1447 * in this case we remove the m->swapblk assignment for the page 1448 * but do not free it in the rlist. The errornous block(s) are thus 1449 * never reallocated as swap. Redirty the page and continue. 1450 */ 1451 for (i = 0; i < bp->b_npages; ++i) { 1452 vm_page_t m = bp->b_pages[i]; 1453 1454 vm_page_flag_clear(m, PG_SWAPINPROG); 1455 1456 if (bp->b_ioflags & BIO_ERROR) { 1457 /* 1458 * If an error occurs I'd love to throw the swapblk 1459 * away without freeing it back to swapspace, so it 1460 * can never be used again. But I can't from an 1461 * interrupt. 1462 */ 1463 if (bp->b_iocmd == BIO_READ) { 1464 /* 1465 * When reading, reqpage needs to stay 1466 * locked for the parent, but all other 1467 * pages can be freed. We still want to 1468 * wakeup the parent waiting on the page, 1469 * though. ( also: pg_reqpage can be -1 and 1470 * not match anything ). 1471 * 1472 * We have to wake specifically requested pages 1473 * up too because we cleared PG_SWAPINPROG and 1474 * someone may be waiting for that. 1475 * 1476 * NOTE: for reads, m->dirty will probably 1477 * be overridden by the original caller of 1478 * getpages so don't play cute tricks here. 1479 * 1480 * XXX IT IS NOT LEGAL TO FREE THE PAGE HERE 1481 * AS THIS MESSES WITH object->memq, and it is 1482 * not legal to mess with object->memq from an 1483 * interrupt. 1484 */ 1485 m->valid = 0; 1486 if (i != bp->b_pager.pg_reqpage) 1487 vm_page_free(m); 1488 else 1489 vm_page_flash(m); 1490 /* 1491 * If i == bp->b_pager.pg_reqpage, do not wake 1492 * the page up. The caller needs to. 1493 */ 1494 } else { 1495 /* 1496 * If a write error occurs, reactivate page 1497 * so it doesn't clog the inactive list, 1498 * then finish the I/O. 1499 */ 1500 vm_page_dirty(m); 1501 vm_page_activate(m); 1502 vm_page_io_finish(m); 1503 } 1504 } else if (bp->b_iocmd == BIO_READ) { 1505 /* 1506 * For read success, clear dirty bits. Nobody should 1507 * have this page mapped but don't take any chances, 1508 * make sure the pmap modify bits are also cleared. 1509 * 1510 * NOTE: for reads, m->dirty will probably be 1511 * overridden by the original caller of getpages so 1512 * we cannot set them in order to free the underlying 1513 * swap in a low-swap situation. I don't think we'd 1514 * want to do that anyway, but it was an optimization 1515 * that existed in the old swapper for a time before 1516 * it got ripped out due to precisely this problem. 1517 * 1518 * If not the requested page then deactivate it. 1519 * 1520 * Note that the requested page, reqpage, is left 1521 * busied, but we still have to wake it up. The 1522 * other pages are released (unbusied) by 1523 * vm_page_wakeup(). We do not set reqpage's 1524 * valid bits here, it is up to the caller. 1525 */ 1526 pmap_clear_modify(m); 1527 m->valid = VM_PAGE_BITS_ALL; 1528 vm_page_undirty(m); 1529 1530 /* 1531 * We have to wake specifically requested pages 1532 * up too because we cleared PG_SWAPINPROG and 1533 * could be waiting for it in getpages. However, 1534 * be sure to not unbusy getpages specifically 1535 * requested page - getpages expects it to be 1536 * left busy. 1537 */ 1538 if (i != bp->b_pager.pg_reqpage) { 1539 vm_page_deactivate(m); 1540 vm_page_wakeup(m); 1541 } else { 1542 vm_page_flash(m); 1543 } 1544 } else { 1545 /* 1546 * For write success, clear the modify and dirty 1547 * status, then finish the I/O ( which decrements the 1548 * busy count and possibly wakes waiter's up ). 1549 */ 1550 pmap_clear_modify(m); 1551 vm_page_undirty(m); 1552 vm_page_io_finish(m); 1553 if (vm_page_count_severe()) 1554 vm_page_try_to_cache(m); 1555 } 1556 } 1557 vm_page_unlock_queues(); 1558 1559 /* 1560 * adjust pip. NOTE: the original parent may still have its own 1561 * pip refs on the object. 1562 */ 1563 if (object != NULL) { 1564 vm_object_pip_wakeupn(object, bp->b_npages); 1565 VM_OBJECT_UNLOCK(object); 1566 } 1567 1568 /* 1569 * release the physical I/O buffer 1570 */ 1571 relpbuf( 1572 bp, 1573 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount : 1574 ((bp->b_flags & B_ASYNC) ? 1575 &nsw_wcount_async : 1576 &nsw_wcount_sync 1577 ) 1578 ) 1579 ); 1580 splx(s); 1581} 1582 1583/* 1584 * swap_pager_isswapped: 1585 * 1586 * Return 1 if at least one page in the given object is paged 1587 * out to the given swap device. 1588 * 1589 * This routine may not block. 1590 */ 1591int 1592swap_pager_isswapped(vm_object_t object, struct swdevt *sp) 1593{ 1594 daddr_t index = 0; 1595 int bcount; 1596 int i; 1597 1598 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1599 for (bcount = 0; bcount < object->un_pager.swp.swp_bcount; bcount++) { 1600 struct swblock *swap; 1601 1602 mtx_lock(&swhash_mtx); 1603 if ((swap = *swp_pager_hash(object, index)) != NULL) { 1604 for (i = 0; i < SWAP_META_PAGES; ++i) { 1605 daddr_t v = swap->swb_pages[i]; 1606 if (v == SWAPBLK_NONE) 1607 continue; 1608 if (swp_pager_find_dev(v) == sp) { 1609 mtx_unlock(&swhash_mtx); 1610 return 1; 1611 } 1612 } 1613 } 1614 mtx_unlock(&swhash_mtx); 1615 index += SWAP_META_PAGES; 1616 if (index > 0x20000000) 1617 panic("swap_pager_isswapped: failed to locate all swap meta blocks"); 1618 } 1619 return 0; 1620} 1621 1622/* 1623 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in 1624 * 1625 * This routine dissociates the page at the given index within a 1626 * swap block from its backing store, paging it in if necessary. 1627 * If the page is paged in, it is placed in the inactive queue, 1628 * since it had its backing store ripped out from under it. 1629 * We also attempt to swap in all other pages in the swap block, 1630 * we only guarantee that the one at the specified index is 1631 * paged in. 1632 * 1633 * XXX - The code to page the whole block in doesn't work, so we 1634 * revert to the one-by-one behavior for now. Sigh. 1635 */ 1636static __inline void 1637swp_pager_force_pagein(struct swblock *swap, int idx) 1638{ 1639 vm_object_t object; 1640 vm_page_t m; 1641 vm_pindex_t pindex; 1642 1643 object = swap->swb_object; 1644 pindex = swap->swb_index; 1645 mtx_unlock(&swhash_mtx); 1646 1647 VM_OBJECT_LOCK(object); 1648 vm_object_pip_add(object, 1); 1649 m = vm_page_grab(object, pindex + idx, VM_ALLOC_NORMAL|VM_ALLOC_RETRY); 1650 if (m->valid == VM_PAGE_BITS_ALL) { 1651 vm_object_pip_subtract(object, 1); 1652 vm_page_lock_queues(); 1653 vm_page_activate(m); 1654 vm_page_dirty(m); 1655 vm_page_wakeup(m); 1656 vm_page_unlock_queues(); 1657 vm_pager_page_unswapped(m); 1658 VM_OBJECT_UNLOCK(object); 1659 return; 1660 } 1661 1662 if (swap_pager_getpages(object, &m, 1, 0) != 1663 VM_PAGER_OK) 1664 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/ 1665 vm_object_pip_subtract(object, 1); 1666 vm_page_lock_queues(); 1667 vm_page_dirty(m); 1668 vm_page_dontneed(m); 1669 vm_page_wakeup(m); 1670 vm_page_unlock_queues(); 1671 vm_pager_page_unswapped(m); 1672 VM_OBJECT_UNLOCK(object); 1673} 1674 1675 1676/* 1677 * swap_pager_swapoff: 1678 * 1679 * Page in all of the pages that have been paged out to the 1680 * given device. The corresponding blocks in the bitmap must be 1681 * marked as allocated and the device must be flagged SW_CLOSING. 1682 * There may be no processes swapped out to the device. 1683 * 1684 * The sw_used parameter points to the field in the swdev structure 1685 * that contains a count of the number of blocks still allocated 1686 * on the device. If we encounter objects with a nonzero pip count 1687 * in our scan, we use this number to determine if we're really done. 1688 * 1689 * This routine may block. 1690 */ 1691static void 1692swap_pager_swapoff(struct swdevt *sp, int *sw_used) 1693{ 1694 struct swblock **pswap; 1695 struct swblock *swap; 1696 vm_object_t waitobj; 1697 daddr_t v; 1698 int i, j; 1699 1700 GIANT_REQUIRED; 1701 1702full_rescan: 1703 waitobj = NULL; 1704 for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */ 1705restart: 1706 pswap = &swhash[i]; 1707 mtx_lock(&swhash_mtx); 1708 while ((swap = *pswap) != NULL) { 1709 for (j = 0; j < SWAP_META_PAGES; ++j) { 1710 v = swap->swb_pages[j]; 1711 if (v != SWAPBLK_NONE && 1712 swp_pager_find_dev(v) == sp) 1713 break; 1714 } 1715 if (j < SWAP_META_PAGES) { 1716 swp_pager_force_pagein(swap, j); 1717 goto restart; 1718 } else if (swap->swb_object->paging_in_progress) { 1719 if (!waitobj) 1720 waitobj = swap->swb_object; 1721 } 1722 pswap = &swap->swb_hnext; 1723 } 1724 mtx_unlock(&swhash_mtx); 1725 } 1726 if (waitobj && *sw_used) { 1727 /* 1728 * We wait on an arbitrary object to clock our rescans 1729 * to the rate of paging completion. 1730 */ 1731 VM_OBJECT_LOCK(waitobj); 1732 vm_object_pip_wait(waitobj, "swpoff"); 1733 VM_OBJECT_UNLOCK(waitobj); 1734 goto full_rescan; 1735 } 1736 if (*sw_used) 1737 panic("swapoff: failed to locate %d swap blocks", *sw_used); 1738} 1739 1740/************************************************************************ 1741 * SWAP META DATA * 1742 ************************************************************************ 1743 * 1744 * These routines manipulate the swap metadata stored in the 1745 * OBJT_SWAP object. All swp_*() routines must be called at 1746 * splvm() because swap can be freed up by the low level vm_page 1747 * code which might be called from interrupts beyond what splbio() covers. 1748 * 1749 * Swap metadata is implemented with a global hash and not directly 1750 * linked into the object. Instead the object simply contains 1751 * appropriate tracking counters. 1752 */ 1753 1754/* 1755 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1756 * 1757 * We first convert the object to a swap object if it is a default 1758 * object. 1759 * 1760 * The specified swapblk is added to the object's swap metadata. If 1761 * the swapblk is not valid, it is freed instead. Any previously 1762 * assigned swapblk is freed. 1763 * 1764 * This routine must be called at splvm(), except when used to convert 1765 * an OBJT_DEFAULT object into an OBJT_SWAP object. 1766 */ 1767static void 1768swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1769{ 1770 struct swblock *swap; 1771 struct swblock **pswap; 1772 int idx; 1773 1774 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1775 /* 1776 * Convert default object to swap object if necessary 1777 */ 1778 if (object->type != OBJT_SWAP) { 1779 object->type = OBJT_SWAP; 1780 object->un_pager.swp.swp_bcount = 0; 1781 1782 if (object->handle != NULL) { 1783 mtx_lock(&sw_alloc_mtx); 1784 TAILQ_INSERT_TAIL( 1785 NOBJLIST(object->handle), 1786 object, 1787 pager_object_list 1788 ); 1789 mtx_unlock(&sw_alloc_mtx); 1790 } 1791 } 1792 1793 /* 1794 * Locate hash entry. If not found create, but if we aren't adding 1795 * anything just return. If we run out of space in the map we wait 1796 * and, since the hash table may have changed, retry. 1797 */ 1798retry: 1799 mtx_lock(&swhash_mtx); 1800 pswap = swp_pager_hash(object, pindex); 1801 1802 if ((swap = *pswap) == NULL) { 1803 int i; 1804 1805 if (swapblk == SWAPBLK_NONE) 1806 goto done; 1807 1808 swap = *pswap = uma_zalloc(swap_zone, M_NOWAIT); 1809 if (swap == NULL) { 1810 mtx_unlock(&swhash_mtx); 1811 VM_OBJECT_UNLOCK(object); 1812 VM_WAIT; 1813 VM_OBJECT_LOCK(object); 1814 goto retry; 1815 } 1816 1817 swap->swb_hnext = NULL; 1818 swap->swb_object = object; 1819 swap->swb_index = pindex & ~(vm_pindex_t)SWAP_META_MASK; 1820 swap->swb_count = 0; 1821 1822 ++object->un_pager.swp.swp_bcount; 1823 1824 for (i = 0; i < SWAP_META_PAGES; ++i) 1825 swap->swb_pages[i] = SWAPBLK_NONE; 1826 } 1827 1828 /* 1829 * Delete prior contents of metadata 1830 */ 1831 idx = pindex & SWAP_META_MASK; 1832 1833 if (swap->swb_pages[idx] != SWAPBLK_NONE) { 1834 swp_pager_freeswapspace(swap->swb_pages[idx], 1); 1835 --swap->swb_count; 1836 } 1837 1838 /* 1839 * Enter block into metadata 1840 */ 1841 swap->swb_pages[idx] = swapblk; 1842 if (swapblk != SWAPBLK_NONE) 1843 ++swap->swb_count; 1844done: 1845 mtx_unlock(&swhash_mtx); 1846} 1847 1848/* 1849 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 1850 * 1851 * The requested range of blocks is freed, with any associated swap 1852 * returned to the swap bitmap. 1853 * 1854 * This routine will free swap metadata structures as they are cleaned 1855 * out. This routine does *NOT* operate on swap metadata associated 1856 * with resident pages. 1857 * 1858 * This routine must be called at splvm() 1859 */ 1860static void 1861swp_pager_meta_free(vm_object_t object, vm_pindex_t index, daddr_t count) 1862{ 1863 1864 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1865 if (object->type != OBJT_SWAP) 1866 return; 1867 1868 while (count > 0) { 1869 struct swblock **pswap; 1870 struct swblock *swap; 1871 1872 mtx_lock(&swhash_mtx); 1873 pswap = swp_pager_hash(object, index); 1874 1875 if ((swap = *pswap) != NULL) { 1876 daddr_t v = swap->swb_pages[index & SWAP_META_MASK]; 1877 1878 if (v != SWAPBLK_NONE) { 1879 swp_pager_freeswapspace(v, 1); 1880 swap->swb_pages[index & SWAP_META_MASK] = 1881 SWAPBLK_NONE; 1882 if (--swap->swb_count == 0) { 1883 *pswap = swap->swb_hnext; 1884 uma_zfree(swap_zone, swap); 1885 --object->un_pager.swp.swp_bcount; 1886 } 1887 } 1888 --count; 1889 ++index; 1890 } else { 1891 int n = SWAP_META_PAGES - (index & SWAP_META_MASK); 1892 count -= n; 1893 index += n; 1894 } 1895 mtx_unlock(&swhash_mtx); 1896 } 1897} 1898 1899/* 1900 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 1901 * 1902 * This routine locates and destroys all swap metadata associated with 1903 * an object. 1904 * 1905 * This routine must be called at splvm() 1906 */ 1907static void 1908swp_pager_meta_free_all(vm_object_t object) 1909{ 1910 daddr_t index = 0; 1911 1912 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1913 if (object->type != OBJT_SWAP) 1914 return; 1915 1916 while (object->un_pager.swp.swp_bcount) { 1917 struct swblock **pswap; 1918 struct swblock *swap; 1919 1920 mtx_lock(&swhash_mtx); 1921 pswap = swp_pager_hash(object, index); 1922 if ((swap = *pswap) != NULL) { 1923 int i; 1924 1925 for (i = 0; i < SWAP_META_PAGES; ++i) { 1926 daddr_t v = swap->swb_pages[i]; 1927 if (v != SWAPBLK_NONE) { 1928 --swap->swb_count; 1929 swp_pager_freeswapspace(v, 1); 1930 } 1931 } 1932 if (swap->swb_count != 0) 1933 panic("swap_pager_meta_free_all: swb_count != 0"); 1934 *pswap = swap->swb_hnext; 1935 uma_zfree(swap_zone, swap); 1936 --object->un_pager.swp.swp_bcount; 1937 } 1938 mtx_unlock(&swhash_mtx); 1939 index += SWAP_META_PAGES; 1940 if (index > 0x20000000) 1941 panic("swp_pager_meta_free_all: failed to locate all swap meta blocks"); 1942 } 1943} 1944 1945/* 1946 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. 1947 * 1948 * This routine is capable of looking up, popping, or freeing 1949 * swapblk assignments in the swap meta data or in the vm_page_t. 1950 * The routine typically returns the swapblk being looked-up, or popped, 1951 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block 1952 * was invalid. This routine will automatically free any invalid 1953 * meta-data swapblks. 1954 * 1955 * It is not possible to store invalid swapblks in the swap meta data 1956 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking. 1957 * 1958 * When acting on a busy resident page and paging is in progress, we 1959 * have to wait until paging is complete but otherwise can act on the 1960 * busy page. 1961 * 1962 * This routine must be called at splvm(). 1963 * 1964 * SWM_FREE remove and free swap block from metadata 1965 * SWM_POP remove from meta data but do not free.. pop it out 1966 */ 1967static daddr_t 1968swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags) 1969{ 1970 struct swblock **pswap; 1971 struct swblock *swap; 1972 daddr_t r1; 1973 int idx; 1974 1975 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1976 /* 1977 * The meta data only exists of the object is OBJT_SWAP 1978 * and even then might not be allocated yet. 1979 */ 1980 if (object->type != OBJT_SWAP) 1981 return (SWAPBLK_NONE); 1982 1983 r1 = SWAPBLK_NONE; 1984 mtx_lock(&swhash_mtx); 1985 pswap = swp_pager_hash(object, pindex); 1986 1987 if ((swap = *pswap) != NULL) { 1988 idx = pindex & SWAP_META_MASK; 1989 r1 = swap->swb_pages[idx]; 1990 1991 if (r1 != SWAPBLK_NONE) { 1992 if (flags & SWM_FREE) { 1993 swp_pager_freeswapspace(r1, 1); 1994 r1 = SWAPBLK_NONE; 1995 } 1996 if (flags & (SWM_FREE|SWM_POP)) { 1997 swap->swb_pages[idx] = SWAPBLK_NONE; 1998 if (--swap->swb_count == 0) { 1999 *pswap = swap->swb_hnext; 2000 uma_zfree(swap_zone, swap); 2001 --object->un_pager.swp.swp_bcount; 2002 } 2003 } 2004 } 2005 } 2006 mtx_unlock(&swhash_mtx); 2007 return (r1); 2008} 2009 2010/* 2011 * System call swapon(name) enables swapping on device name, 2012 * which must be in the swdevsw. Return EBUSY 2013 * if already swapping on this device. 2014 */ 2015#ifndef _SYS_SYSPROTO_H_ 2016struct swapon_args { 2017 char *name; 2018}; 2019#endif 2020 2021/* 2022 * MPSAFE 2023 */ 2024/* ARGSUSED */ 2025int 2026swapon(struct thread *td, struct swapon_args *uap) 2027{ 2028 struct vattr attr; 2029 struct vnode *vp; 2030 struct nameidata nd; 2031 int error; 2032 2033 mtx_lock(&Giant); 2034 error = suser(td); 2035 if (error) 2036 goto done2; 2037 2038 while (swdev_syscall_active) 2039 tsleep(&swdev_syscall_active, PUSER - 1, "swpon", 0); 2040 swdev_syscall_active = 1; 2041 2042 /* 2043 * Swap metadata may not fit in the KVM if we have physical 2044 * memory of >1GB. 2045 */ 2046 if (swap_zone == NULL) { 2047 error = ENOMEM; 2048 goto done; 2049 } 2050 2051 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, td); 2052 error = namei(&nd); 2053 if (error) 2054 goto done; 2055 2056 NDFREE(&nd, NDF_ONLY_PNBUF); 2057 vp = nd.ni_vp; 2058 2059 if (vn_isdisk(vp, &error)) { 2060 error = swapongeom(td, vp); 2061 } else if (vp->v_type == VREG && 2062 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2063 (error = VOP_GETATTR(vp, &attr, td->td_ucred, td)) == 0) { 2064 /* 2065 * Allow direct swapping to NFS regular files in the same 2066 * way that nfs_mountroot() sets up diskless swapping. 2067 */ 2068 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2069 } 2070 2071 if (error) 2072 vrele(vp); 2073done: 2074 swdev_syscall_active = 0; 2075 wakeup_one(&swdev_syscall_active); 2076done2: 2077 mtx_unlock(&Giant); 2078 return (error); 2079} 2080 2081static void
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