1 /* 2 * (MPSAFE) 3 * 4 * Copyright (c) 1998-2010 The DragonFly Project. All rights reserved. 5 * 6 * This code is derived from software contributed to The DragonFly Project 7 * by Matthew Dillon <dillon@backplane.com> 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in 17 * the documentation and/or other materials provided with the 18 * distribution. 19 * 3. Neither the name of The DragonFly Project nor the names of its 20 * contributors may be used to endorse or promote products derived 21 * from this software without specific, prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 24 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 26 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 27 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 29 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 30 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 31 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 32 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 33 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * Copyright (c) 1994 John S. Dyson 37 * Copyright (c) 1990 University of Utah. 38 * Copyright (c) 1991, 1993 39 * The Regents of the University of California. All rights reserved. 40 * 41 * This code is derived from software contributed to Berkeley by 42 * the Systems Programming Group of the University of Utah Computer 43 * Science Department. 44 * 45 * Redistribution and use in source and binary forms, with or without 46 * modification, are permitted provided that the following conditions 47 * are met: 48 * 1. Redistributions of source code must retain the above copyright 49 * notice, this list of conditions and the following disclaimer. 50 * 2. Redistributions in binary form must reproduce the above copyright 51 * notice, this list of conditions and the following disclaimer in the 52 * documentation and/or other materials provided with the distribution. 53 * 3. All advertising materials mentioning features or use of this software 54 * must display the following acknowledgement: 55 * This product includes software developed by the University of 56 * California, Berkeley and its contributors. 57 * 4. Neither the name of the University nor the names of its contributors 58 * may be used to endorse or promote products derived from this software 59 * without specific prior written permission. 60 * 61 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 62 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 63 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 64 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 65 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 66 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 67 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 68 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 69 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 70 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 71 * SUCH DAMAGE. 72 * 73 * New Swap System 74 * Matthew Dillon 75 * 76 * Radix Bitmap 'blists'. 77 * 78 * - The new swapper uses the new radix bitmap code. This should scale 79 * to arbitrarily small or arbitrarily large swap spaces and an almost 80 * arbitrary degree of fragmentation. 81 * 82 * Features: 83 * 84 * - on the fly reallocation of swap during putpages. The new system 85 * does not try to keep previously allocated swap blocks for dirty 86 * pages. 87 * 88 * - on the fly deallocation of swap 89 * 90 * - No more garbage collection required. Unnecessarily allocated swap 91 * blocks only exist for dirty vm_page_t's now and these are already 92 * cycled (in a high-load system) by the pager. We also do on-the-fly 93 * removal of invalidated swap blocks when a page is destroyed 94 * or renamed. 95 * 96 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$ 97 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94 98 * $FreeBSD: src/sys/vm/swap_pager.c,v 1.130.2.12 2002/08/31 21:15:55 dillon Exp $ 99 */ 100 101 #include <sys/param.h> 102 #include <sys/systm.h> 103 #include <sys/conf.h> 104 #include <sys/kernel.h> 105 #include <sys/proc.h> 106 #include <sys/buf.h> 107 #include <sys/vnode.h> 108 #include <sys/malloc.h> 109 #include <sys/vmmeter.h> 110 #include <sys/sysctl.h> 111 #include <sys/blist.h> 112 #include <sys/lock.h> 113 #include <sys/thread2.h> 114 115 #ifndef MAX_PAGEOUT_CLUSTER 116 #define MAX_PAGEOUT_CLUSTER 16 117 #endif 118 119 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER 120 121 #include "opt_swap.h" 122 #include <vm/vm.h> 123 #include <vm/vm_object.h> 124 #include <vm/vm_page.h> 125 #include <vm/vm_pager.h> 126 #include <vm/vm_pageout.h> 127 #include <vm/swap_pager.h> 128 #include <vm/vm_extern.h> 129 #include <vm/vm_zone.h> 130 #include <vm/vnode_pager.h> 131 132 #include <sys/buf2.h> 133 #include <vm/vm_page2.h> 134 135 #define SWM_FREE 0x02 /* free, period */ 136 #define SWM_POP 0x04 /* pop out */ 137 138 #define SWBIO_READ 0x01 139 #define SWBIO_WRITE 0x02 140 #define SWBIO_SYNC 0x04 141 142 struct swfreeinfo { 143 vm_object_t object; 144 vm_pindex_t basei; 145 vm_pindex_t begi; 146 vm_pindex_t endi; /* inclusive */ 147 }; 148 149 /* 150 * vm_swap_size is in page-sized chunks now. It was DEV_BSIZE'd chunks 151 * in the old system. 152 */ 153 154 int swap_pager_full; /* swap space exhaustion (task killing) */ 155 int vm_swap_cache_use; 156 int vm_swap_anon_use; 157 158 static int swap_pager_almost_full; /* swap space exhaustion (w/ hysteresis)*/ 159 static int nsw_rcount; /* free read buffers */ 160 static int nsw_wcount_sync; /* limit write buffers / synchronous */ 161 static int nsw_wcount_async; /* limit write buffers / asynchronous */ 162 static int nsw_wcount_async_max;/* assigned maximum */ 163 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 164 165 struct blist *swapblist; 166 static int swap_async_max = 4; /* maximum in-progress async I/O's */ 167 static int swap_burst_read = 0; /* allow burst reading */ 168 169 /* from vm_swap.c */ 170 extern struct vnode *swapdev_vp; 171 extern struct swdevt *swdevt; 172 extern int nswdev; 173 174 #define BLK2DEVIDX(blk) (nswdev > 1 ? blk / dmmax % nswdev : 0) 175 176 SYSCTL_INT(_vm, OID_AUTO, swap_async_max, 177 CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops"); 178 SYSCTL_INT(_vm, OID_AUTO, swap_burst_read, 179 CTLFLAG_RW, &swap_burst_read, 0, "Allow burst reads for pageins"); 180 181 SYSCTL_INT(_vm, OID_AUTO, swap_cache_use, 182 CTLFLAG_RD, &vm_swap_cache_use, 0, ""); 183 SYSCTL_INT(_vm, OID_AUTO, swap_anon_use, 184 CTLFLAG_RD, &vm_swap_anon_use, 0, ""); 185 SYSCTL_INT(_vm, OID_AUTO, swap_size, 186 CTLFLAG_RD, &vm_swap_size, 0, ""); 187 188 vm_zone_t swap_zone; 189 190 /* 191 * Red-Black tree for swblock entries 192 * 193 * The caller must hold vm_token 194 */ 195 RB_GENERATE2(swblock_rb_tree, swblock, swb_entry, rb_swblock_compare, 196 vm_pindex_t, swb_index); 197 198 int 199 rb_swblock_compare(struct swblock *swb1, struct swblock *swb2) 200 { 201 if (swb1->swb_index < swb2->swb_index) 202 return(-1); 203 if (swb1->swb_index > swb2->swb_index) 204 return(1); 205 return(0); 206 } 207 208 static 209 int 210 rb_swblock_scancmp(struct swblock *swb, void *data) 211 { 212 struct swfreeinfo *info = data; 213 214 if (swb->swb_index < info->basei) 215 return(-1); 216 if (swb->swb_index > info->endi) 217 return(1); 218 return(0); 219 } 220 221 static 222 int 223 rb_swblock_condcmp(struct swblock *swb, void *data) 224 { 225 struct swfreeinfo *info = data; 226 227 if (swb->swb_index < info->basei) 228 return(-1); 229 return(0); 230 } 231 232 /* 233 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 234 * calls hooked from other parts of the VM system and do not appear here. 235 * (see vm/swap_pager.h). 236 */ 237 238 static void swap_pager_dealloc (vm_object_t object); 239 static int swap_pager_getpage (vm_object_t, vm_page_t *, int); 240 static void swap_chain_iodone(struct bio *biox); 241 242 struct pagerops swappagerops = { 243 swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 244 swap_pager_getpage, /* pagein */ 245 swap_pager_putpages, /* pageout */ 246 swap_pager_haspage /* get backing store status for page */ 247 }; 248 249 /* 250 * dmmax is in page-sized chunks with the new swap system. It was 251 * dev-bsized chunks in the old. dmmax is always a power of 2. 252 * 253 * swap_*() routines are externally accessible. swp_*() routines are 254 * internal. 255 */ 256 257 int dmmax; 258 static int dmmax_mask; 259 int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 260 int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 261 262 static __inline void swp_sizecheck (void); 263 static void swp_pager_async_iodone (struct bio *bio); 264 265 /* 266 * Swap bitmap functions 267 */ 268 269 static __inline void swp_pager_freeswapspace(vm_object_t object, 270 swblk_t blk, int npages); 271 static __inline swblk_t swp_pager_getswapspace(vm_object_t object, int npages); 272 273 /* 274 * Metadata functions 275 */ 276 277 static void swp_pager_meta_convert(vm_object_t); 278 static void swp_pager_meta_build(vm_object_t, vm_pindex_t, swblk_t); 279 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 280 static void swp_pager_meta_free_all(vm_object_t); 281 static swblk_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 282 283 /* 284 * SWP_SIZECHECK() - update swap_pager_full indication 285 * 286 * update the swap_pager_almost_full indication and warn when we are 287 * about to run out of swap space, using lowat/hiwat hysteresis. 288 * 289 * Clear swap_pager_full ( task killing ) indication when lowat is met. 290 * 291 * No restrictions on call 292 * This routine may not block. 293 * SMP races are ok. 294 */ 295 static __inline void 296 swp_sizecheck(void) 297 { 298 if (vm_swap_size < nswap_lowat) { 299 if (swap_pager_almost_full == 0) { 300 kprintf("swap_pager: out of swap space\n"); 301 swap_pager_almost_full = 1; 302 } 303 } else { 304 swap_pager_full = 0; 305 if (vm_swap_size > nswap_hiwat) 306 swap_pager_almost_full = 0; 307 } 308 } 309 310 /* 311 * SWAP_PAGER_INIT() - initialize the swap pager! 312 * 313 * Expected to be started from system init. NOTE: This code is run 314 * before much else so be careful what you depend on. Most of the VM 315 * system has yet to be initialized at this point. 316 * 317 * Called from the low level boot code only. 318 */ 319 static void 320 swap_pager_init(void *arg __unused) 321 { 322 /* 323 * Device Stripe, in PAGE_SIZE'd blocks 324 */ 325 dmmax = SWB_NPAGES * 2; 326 dmmax_mask = ~(dmmax - 1); 327 } 328 SYSINIT(vm_mem, SI_BOOT1_VM, SI_ORDER_THIRD, swap_pager_init, NULL) 329 330 /* 331 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 332 * 333 * Expected to be started from pageout process once, prior to entering 334 * its main loop. 335 * 336 * Called from the low level boot code only. 337 */ 338 void 339 swap_pager_swap_init(void) 340 { 341 int n, n2; 342 343 /* 344 * Number of in-transit swap bp operations. Don't 345 * exhaust the pbufs completely. Make sure we 346 * initialize workable values (0 will work for hysteresis 347 * but it isn't very efficient). 348 * 349 * The nsw_cluster_max is constrained by the number of pages an XIO 350 * holds, i.e., (MAXPHYS/PAGE_SIZE) and our locally defined 351 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 352 * constrained by the swap device interleave stripe size. 353 * 354 * Currently we hardwire nsw_wcount_async to 4. This limit is 355 * designed to prevent other I/O from having high latencies due to 356 * our pageout I/O. The value 4 works well for one or two active swap 357 * devices but is probably a little low if you have more. Even so, 358 * a higher value would probably generate only a limited improvement 359 * with three or four active swap devices since the system does not 360 * typically have to pageout at extreme bandwidths. We will want 361 * at least 2 per swap devices, and 4 is a pretty good value if you 362 * have one NFS swap device due to the command/ack latency over NFS. 363 * So it all works out pretty well. 364 */ 365 366 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER); 367 368 nsw_rcount = (nswbuf + 1) / 2; 369 nsw_wcount_sync = (nswbuf + 3) / 4; 370 nsw_wcount_async = 4; 371 nsw_wcount_async_max = nsw_wcount_async; 372 373 /* 374 * The zone is dynamically allocated so generally size it to 375 * maxswzone (32MB to 512MB of KVM). Set a minimum size based 376 * on physical memory of around 8x (each swblock can hold 16 pages). 377 * 378 * With the advent of SSDs (vs HDs) the practical (swap:memory) ratio 379 * has increased dramatically. 380 */ 381 n = vmstats.v_page_count / 2; 382 if (maxswzone && n < maxswzone / sizeof(struct swblock)) 383 n = maxswzone / sizeof(struct swblock); 384 n2 = n; 385 386 do { 387 swap_zone = zinit( 388 "SWAPMETA", 389 sizeof(struct swblock), 390 n, 391 ZONE_INTERRUPT, 392 1); 393 if (swap_zone != NULL) 394 break; 395 /* 396 * if the allocation failed, try a zone two thirds the 397 * size of the previous attempt. 398 */ 399 n -= ((n + 2) / 3); 400 } while (n > 0); 401 402 if (swap_zone == NULL) 403 panic("swap_pager_swap_init: swap_zone == NULL"); 404 if (n2 != n) 405 kprintf("Swap zone entries reduced from %d to %d.\n", n2, n); 406 } 407 408 /* 409 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 410 * its metadata structures. 411 * 412 * This routine is called from the mmap and fork code to create a new 413 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object 414 * and then converting it with swp_pager_meta_convert(). 415 * 416 * We only support unnamed objects. 417 * 418 * No restrictions. 419 */ 420 vm_object_t 421 swap_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t offset) 422 { 423 vm_object_t object; 424 425 KKASSERT(handle == NULL); 426 object = vm_object_allocate(OBJT_DEFAULT, 427 OFF_TO_IDX(offset + PAGE_MASK + size)); 428 vm_object_hold(object); 429 swp_pager_meta_convert(object); 430 vm_object_drop(object); 431 432 return (object); 433 } 434 435 /* 436 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 437 * 438 * The swap backing for the object is destroyed. The code is 439 * designed such that we can reinstantiate it later, but this 440 * routine is typically called only when the entire object is 441 * about to be destroyed. 442 * 443 * The object must be locked or unreferenceable. 444 * No other requirements. 445 */ 446 static void 447 swap_pager_dealloc(vm_object_t object) 448 { 449 vm_object_hold(object); 450 vm_object_pip_wait(object, "swpdea"); 451 452 /* 453 * Free all remaining metadata. We only bother to free it from 454 * the swap meta data. We do not attempt to free swapblk's still 455 * associated with vm_page_t's for this object. We do not care 456 * if paging is still in progress on some objects. 457 */ 458 swp_pager_meta_free_all(object); 459 vm_object_drop(object); 460 } 461 462 /************************************************************************ 463 * SWAP PAGER BITMAP ROUTINES * 464 ************************************************************************/ 465 466 /* 467 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 468 * 469 * Allocate swap for the requested number of pages. The starting 470 * swap block number (a page index) is returned or SWAPBLK_NONE 471 * if the allocation failed. 472 * 473 * Also has the side effect of advising that somebody made a mistake 474 * when they configured swap and didn't configure enough. 475 * 476 * The caller must hold the object. 477 * This routine may not block. 478 */ 479 static __inline swblk_t 480 swp_pager_getswapspace(vm_object_t object, int npages) 481 { 482 swblk_t blk; 483 484 lwkt_gettoken(&vm_token); 485 if ((blk = blist_alloc(swapblist, npages)) == SWAPBLK_NONE) { 486 if (swap_pager_full != 2) { 487 kprintf("swap_pager_getswapspace: failed\n"); 488 swap_pager_full = 2; 489 swap_pager_almost_full = 1; 490 } 491 } else { 492 swapacctspace(blk, -npages); 493 if (object->type == OBJT_SWAP) 494 vm_swap_anon_use += npages; 495 else 496 vm_swap_cache_use += npages; 497 swp_sizecheck(); 498 } 499 lwkt_reltoken(&vm_token); 500 return(blk); 501 } 502 503 /* 504 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 505 * 506 * This routine returns the specified swap blocks back to the bitmap. 507 * 508 * Note: This routine may not block (it could in the old swap code), 509 * and through the use of the new blist routines it does not block. 510 * 511 * We must be called at splvm() to avoid races with bitmap frees from 512 * vm_page_remove() aka swap_pager_page_removed(). 513 * 514 * This routine may not block. 515 */ 516 517 static __inline void 518 swp_pager_freeswapspace(vm_object_t object, swblk_t blk, int npages) 519 { 520 struct swdevt *sp = &swdevt[BLK2DEVIDX(blk)]; 521 522 lwkt_gettoken(&vm_token); 523 sp->sw_nused -= npages; 524 if (object->type == OBJT_SWAP) 525 vm_swap_anon_use -= npages; 526 else 527 vm_swap_cache_use -= npages; 528 529 if (sp->sw_flags & SW_CLOSING) { 530 lwkt_reltoken(&vm_token); 531 return; 532 } 533 534 blist_free(swapblist, blk, npages); 535 vm_swap_size += npages; 536 swp_sizecheck(); 537 lwkt_reltoken(&vm_token); 538 } 539 540 /* 541 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 542 * range within an object. 543 * 544 * This is a globally accessible routine. 545 * 546 * This routine removes swapblk assignments from swap metadata. 547 * 548 * The external callers of this routine typically have already destroyed 549 * or renamed vm_page_t's associated with this range in the object so 550 * we should be ok. 551 * 552 * No requirements. 553 */ 554 void 555 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_pindex_t size) 556 { 557 vm_object_hold(object); 558 swp_pager_meta_free(object, start, size); 559 vm_object_drop(object); 560 } 561 562 /* 563 * No requirements. 564 */ 565 void 566 swap_pager_freespace_all(vm_object_t object) 567 { 568 vm_object_hold(object); 569 swp_pager_meta_free_all(object); 570 vm_object_drop(object); 571 } 572 573 /* 574 * This function conditionally frees swap cache swap starting at 575 * (*basei) in the object. (count) swap blocks will be nominally freed. 576 * The actual number of blocks freed can be more or less than the 577 * requested number. 578 * 579 * This function nominally returns the number of blocks freed. However, 580 * the actual number of blocks freed may be less then the returned value. 581 * If the function is unable to exhaust the object or if it is able to 582 * free (approximately) the requested number of blocks it returns 583 * a value n > count. 584 * 585 * If we exhaust the object we will return a value n <= count. 586 * 587 * The caller must hold the object. 588 * 589 * WARNING! If count == 0 then -1 can be returned as a degenerate case, 590 * callers should always pass a count value > 0. 591 */ 592 static int swap_pager_condfree_callback(struct swblock *swap, void *data); 593 594 int 595 swap_pager_condfree(vm_object_t object, vm_pindex_t *basei, int count) 596 { 597 struct swfreeinfo info; 598 599 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 600 601 info.object = object; 602 info.basei = *basei; /* skip up to this page index */ 603 info.begi = count; /* max swap pages to destroy */ 604 info.endi = count * 8; /* max swblocks to scan */ 605 606 swblock_rb_tree_RB_SCAN(&object->swblock_root, rb_swblock_condcmp, 607 swap_pager_condfree_callback, &info); 608 *basei = info.basei; 609 if (info.endi < 0 && info.begi <= count) 610 info.begi = count + 1; 611 return(count - (int)info.begi); 612 } 613 614 /* 615 * The idea is to free whole meta-block to avoid fragmenting 616 * the swap space or disk I/O. We only do this if NO VM pages 617 * are present. 618 * 619 * We do not have to deal with clearing PG_SWAPPED in related VM 620 * pages because there are no related VM pages. 621 * 622 * The caller must hold the object. 623 */ 624 static int 625 swap_pager_condfree_callback(struct swblock *swap, void *data) 626 { 627 struct swfreeinfo *info = data; 628 vm_object_t object = info->object; 629 int i; 630 631 for (i = 0; i < SWAP_META_PAGES; ++i) { 632 if (vm_page_lookup(object, swap->swb_index + i)) 633 break; 634 } 635 info->basei = swap->swb_index + SWAP_META_PAGES; 636 if (i == SWAP_META_PAGES) { 637 info->begi -= swap->swb_count; 638 swap_pager_freespace(object, swap->swb_index, SWAP_META_PAGES); 639 } 640 --info->endi; 641 if ((int)info->begi < 0 || (int)info->endi < 0) 642 return(-1); 643 lwkt_yield(); 644 return(0); 645 } 646 647 /* 648 * Called by vm_page_alloc() when a new VM page is inserted 649 * into a VM object. Checks whether swap has been assigned to 650 * the page and sets PG_SWAPPED as necessary. 651 * 652 * No requirements. 653 */ 654 void 655 swap_pager_page_inserted(vm_page_t m) 656 { 657 if (m->object->swblock_count) { 658 vm_object_hold(m->object); 659 if (swp_pager_meta_ctl(m->object, m->pindex, 0) != SWAPBLK_NONE) 660 vm_page_flag_set(m, PG_SWAPPED); 661 vm_object_drop(m->object); 662 } 663 } 664 665 /* 666 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 667 * 668 * Assigns swap blocks to the specified range within the object. The 669 * swap blocks are not zerod. Any previous swap assignment is destroyed. 670 * 671 * Returns 0 on success, -1 on failure. 672 * 673 * The caller is responsible for avoiding races in the specified range. 674 * No other requirements. 675 */ 676 int 677 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 678 { 679 int n = 0; 680 swblk_t blk = SWAPBLK_NONE; 681 vm_pindex_t beg = start; /* save start index */ 682 683 vm_object_hold(object); 684 685 while (size) { 686 if (n == 0) { 687 n = BLIST_MAX_ALLOC; 688 while ((blk = swp_pager_getswapspace(object, n)) == 689 SWAPBLK_NONE) 690 { 691 n >>= 1; 692 if (n == 0) { 693 swp_pager_meta_free(object, beg, 694 start - beg); 695 vm_object_drop(object); 696 return(-1); 697 } 698 } 699 } 700 swp_pager_meta_build(object, start, blk); 701 --size; 702 ++start; 703 ++blk; 704 --n; 705 } 706 swp_pager_meta_free(object, start, n); 707 vm_object_drop(object); 708 return(0); 709 } 710 711 /* 712 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 713 * and destroy the source. 714 * 715 * Copy any valid swapblks from the source to the destination. In 716 * cases where both the source and destination have a valid swapblk, 717 * we keep the destination's. 718 * 719 * This routine is allowed to block. It may block allocating metadata 720 * indirectly through swp_pager_meta_build() or if paging is still in 721 * progress on the source. 722 * 723 * XXX vm_page_collapse() kinda expects us not to block because we 724 * supposedly do not need to allocate memory, but for the moment we 725 * *may* have to get a little memory from the zone allocator, but 726 * it is taken from the interrupt memory. We should be ok. 727 * 728 * The source object contains no vm_page_t's (which is just as well) 729 * The source object is of type OBJT_SWAP. 730 * 731 * The source and destination objects must be held by the caller. 732 */ 733 void 734 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 735 vm_pindex_t base_index, int destroysource) 736 { 737 vm_pindex_t i; 738 739 ASSERT_LWKT_TOKEN_HELD(vm_object_token(srcobject)); 740 ASSERT_LWKT_TOKEN_HELD(vm_object_token(dstobject)); 741 742 /* 743 * transfer source to destination. 744 */ 745 for (i = 0; i < dstobject->size; ++i) { 746 swblk_t dstaddr; 747 748 /* 749 * Locate (without changing) the swapblk on the destination, 750 * unless it is invalid in which case free it silently, or 751 * if the destination is a resident page, in which case the 752 * source is thrown away. 753 */ 754 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 755 756 if (dstaddr == SWAPBLK_NONE) { 757 /* 758 * Destination has no swapblk and is not resident, 759 * copy source. 760 */ 761 swblk_t srcaddr; 762 763 srcaddr = swp_pager_meta_ctl(srcobject, 764 base_index + i, SWM_POP); 765 766 if (srcaddr != SWAPBLK_NONE) 767 swp_pager_meta_build(dstobject, i, srcaddr); 768 } else { 769 /* 770 * Destination has valid swapblk or it is represented 771 * by a resident page. We destroy the sourceblock. 772 */ 773 swp_pager_meta_ctl(srcobject, base_index + i, SWM_FREE); 774 } 775 } 776 777 /* 778 * Free left over swap blocks in source. 779 * 780 * We have to revert the type to OBJT_DEFAULT so we do not accidently 781 * double-remove the object from the swap queues. 782 */ 783 if (destroysource) { 784 /* 785 * Reverting the type is not necessary, the caller is going 786 * to destroy srcobject directly, but I'm doing it here 787 * for consistency since we've removed the object from its 788 * queues. 789 */ 790 swp_pager_meta_free_all(srcobject); 791 if (srcobject->type == OBJT_SWAP) 792 srcobject->type = OBJT_DEFAULT; 793 } 794 } 795 796 /* 797 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 798 * the requested page. 799 * 800 * We determine whether good backing store exists for the requested 801 * page and return TRUE if it does, FALSE if it doesn't. 802 * 803 * If TRUE, we also try to determine how much valid, contiguous backing 804 * store exists before and after the requested page within a reasonable 805 * distance. We do not try to restrict it to the swap device stripe 806 * (that is handled in getpages/putpages). It probably isn't worth 807 * doing here. 808 * 809 * No requirements. 810 */ 811 boolean_t 812 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex) 813 { 814 swblk_t blk0; 815 816 /* 817 * do we have good backing store at the requested index ? 818 */ 819 vm_object_hold(object); 820 blk0 = swp_pager_meta_ctl(object, pindex, 0); 821 822 if (blk0 == SWAPBLK_NONE) { 823 vm_object_drop(object); 824 return (FALSE); 825 } 826 vm_object_drop(object); 827 return (TRUE); 828 } 829 830 /* 831 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 832 * 833 * This removes any associated swap backing store, whether valid or 834 * not, from the page. This operates on any VM object, not just OBJT_SWAP 835 * objects. 836 * 837 * This routine is typically called when a page is made dirty, at 838 * which point any associated swap can be freed. MADV_FREE also 839 * calls us in a special-case situation 840 * 841 * NOTE!!! If the page is clean and the swap was valid, the caller 842 * should make the page dirty before calling this routine. This routine 843 * does NOT change the m->dirty status of the page. Also: MADV_FREE 844 * depends on it. 845 * 846 * The page must be busied or soft-busied. 847 * The caller can hold the object to avoid blocking, else we might block. 848 * No other requirements. 849 */ 850 void 851 swap_pager_unswapped(vm_page_t m) 852 { 853 if (m->flags & PG_SWAPPED) { 854 vm_object_hold(m->object); 855 KKASSERT(m->flags & PG_SWAPPED); 856 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); 857 vm_page_flag_clear(m, PG_SWAPPED); 858 vm_object_drop(m->object); 859 } 860 } 861 862 /* 863 * SWAP_PAGER_STRATEGY() - read, write, free blocks 864 * 865 * This implements a VM OBJECT strategy function using swap backing store. 866 * This can operate on any VM OBJECT type, not necessarily just OBJT_SWAP 867 * types. 868 * 869 * This is intended to be a cacheless interface (i.e. caching occurs at 870 * higher levels), and is also used as a swap-based SSD cache for vnode 871 * and device objects. 872 * 873 * All I/O goes directly to and from the swap device. 874 * 875 * We currently attempt to run I/O synchronously or asynchronously as 876 * the caller requests. This isn't perfect because we loose error 877 * sequencing when we run multiple ops in parallel to satisfy a request. 878 * But this is swap, so we let it all hang out. 879 * 880 * No requirements. 881 */ 882 void 883 swap_pager_strategy(vm_object_t object, struct bio *bio) 884 { 885 struct buf *bp = bio->bio_buf; 886 struct bio *nbio; 887 vm_pindex_t start; 888 vm_pindex_t biox_blkno = 0; 889 int count; 890 char *data; 891 struct bio *biox; 892 struct buf *bufx; 893 struct bio_track *track; 894 895 /* 896 * tracking for swapdev vnode I/Os 897 */ 898 if (bp->b_cmd == BUF_CMD_READ) 899 track = &swapdev_vp->v_track_read; 900 else 901 track = &swapdev_vp->v_track_write; 902 903 if (bp->b_bcount & PAGE_MASK) { 904 bp->b_error = EINVAL; 905 bp->b_flags |= B_ERROR | B_INVAL; 906 biodone(bio); 907 kprintf("swap_pager_strategy: bp %p offset %lld size %d, " 908 "not page bounded\n", 909 bp, (long long)bio->bio_offset, (int)bp->b_bcount); 910 return; 911 } 912 913 /* 914 * Clear error indication, initialize page index, count, data pointer. 915 */ 916 bp->b_error = 0; 917 bp->b_flags &= ~B_ERROR; 918 bp->b_resid = bp->b_bcount; 919 920 start = (vm_pindex_t)(bio->bio_offset >> PAGE_SHIFT); 921 count = howmany(bp->b_bcount, PAGE_SIZE); 922 data = bp->b_data; 923 924 /* 925 * Deal with BUF_CMD_FREEBLKS 926 */ 927 if (bp->b_cmd == BUF_CMD_FREEBLKS) { 928 /* 929 * FREE PAGE(s) - destroy underlying swap that is no longer 930 * needed. 931 */ 932 vm_object_hold(object); 933 swp_pager_meta_free(object, start, count); 934 vm_object_drop(object); 935 bp->b_resid = 0; 936 biodone(bio); 937 return; 938 } 939 940 /* 941 * We need to be able to create a new cluster of I/O's. We cannot 942 * use the caller fields of the passed bio so push a new one. 943 * 944 * Because nbio is just a placeholder for the cluster links, 945 * we can biodone() the original bio instead of nbio to make 946 * things a bit more efficient. 947 */ 948 nbio = push_bio(bio); 949 nbio->bio_offset = bio->bio_offset; 950 nbio->bio_caller_info1.cluster_head = NULL; 951 nbio->bio_caller_info2.cluster_tail = NULL; 952 953 biox = NULL; 954 bufx = NULL; 955 956 /* 957 * Execute read or write 958 */ 959 vm_object_hold(object); 960 961 while (count > 0) { 962 swblk_t blk; 963 964 /* 965 * Obtain block. If block not found and writing, allocate a 966 * new block and build it into the object. 967 */ 968 blk = swp_pager_meta_ctl(object, start, 0); 969 if ((blk == SWAPBLK_NONE) && bp->b_cmd != BUF_CMD_READ) { 970 blk = swp_pager_getswapspace(object, 1); 971 if (blk == SWAPBLK_NONE) { 972 bp->b_error = ENOMEM; 973 bp->b_flags |= B_ERROR; 974 break; 975 } 976 swp_pager_meta_build(object, start, blk); 977 } 978 979 /* 980 * Do we have to flush our current collection? Yes if: 981 * 982 * - no swap block at this index 983 * - swap block is not contiguous 984 * - we cross a physical disk boundry in the 985 * stripe. 986 */ 987 if ( 988 biox && (biox_blkno + btoc(bufx->b_bcount) != blk || 989 ((biox_blkno ^ blk) & dmmax_mask) 990 ) 991 ) { 992 if (bp->b_cmd == BUF_CMD_READ) { 993 ++mycpu->gd_cnt.v_swapin; 994 mycpu->gd_cnt.v_swappgsin += btoc(bufx->b_bcount); 995 } else { 996 ++mycpu->gd_cnt.v_swapout; 997 mycpu->gd_cnt.v_swappgsout += btoc(bufx->b_bcount); 998 bufx->b_dirtyend = bufx->b_bcount; 999 } 1000 1001 /* 1002 * Finished with this buf. 1003 */ 1004 KKASSERT(bufx->b_bcount != 0); 1005 if (bufx->b_cmd != BUF_CMD_READ) 1006 bufx->b_dirtyend = bufx->b_bcount; 1007 biox = NULL; 1008 bufx = NULL; 1009 } 1010 1011 /* 1012 * Add new swapblk to biox, instantiating biox if necessary. 1013 * Zero-fill reads are able to take a shortcut. 1014 */ 1015 if (blk == SWAPBLK_NONE) { 1016 /* 1017 * We can only get here if we are reading. Since 1018 * we are at splvm() we can safely modify b_resid, 1019 * even if chain ops are in progress. 1020 */ 1021 bzero(data, PAGE_SIZE); 1022 bp->b_resid -= PAGE_SIZE; 1023 } else { 1024 if (biox == NULL) { 1025 /* XXX chain count > 4, wait to <= 4 */ 1026 1027 bufx = getpbuf(NULL); 1028 biox = &bufx->b_bio1; 1029 cluster_append(nbio, bufx); 1030 bufx->b_flags |= (bufx->b_flags & B_ORDERED); 1031 bufx->b_cmd = bp->b_cmd; 1032 biox->bio_done = swap_chain_iodone; 1033 biox->bio_offset = (off_t)blk << PAGE_SHIFT; 1034 biox->bio_caller_info1.cluster_parent = nbio; 1035 biox_blkno = blk; 1036 bufx->b_bcount = 0; 1037 bufx->b_data = data; 1038 } 1039 bufx->b_bcount += PAGE_SIZE; 1040 } 1041 --count; 1042 ++start; 1043 data += PAGE_SIZE; 1044 } 1045 1046 vm_object_drop(object); 1047 1048 /* 1049 * Flush out last buffer 1050 */ 1051 if (biox) { 1052 if (bufx->b_cmd == BUF_CMD_READ) { 1053 ++mycpu->gd_cnt.v_swapin; 1054 mycpu->gd_cnt.v_swappgsin += btoc(bufx->b_bcount); 1055 } else { 1056 ++mycpu->gd_cnt.v_swapout; 1057 mycpu->gd_cnt.v_swappgsout += btoc(bufx->b_bcount); 1058 bufx->b_dirtyend = bufx->b_bcount; 1059 } 1060 KKASSERT(bufx->b_bcount); 1061 if (bufx->b_cmd != BUF_CMD_READ) 1062 bufx->b_dirtyend = bufx->b_bcount; 1063 /* biox, bufx = NULL */ 1064 } 1065 1066 /* 1067 * Now initiate all the I/O. Be careful looping on our chain as 1068 * I/O's may complete while we are still initiating them. 1069 * 1070 * If the request is a 100% sparse read no bios will be present 1071 * and we just biodone() the buffer. 1072 */ 1073 nbio->bio_caller_info2.cluster_tail = NULL; 1074 bufx = nbio->bio_caller_info1.cluster_head; 1075 1076 if (bufx) { 1077 while (bufx) { 1078 biox = &bufx->b_bio1; 1079 BUF_KERNPROC(bufx); 1080 bufx = bufx->b_cluster_next; 1081 vn_strategy(swapdev_vp, biox); 1082 } 1083 } else { 1084 biodone(bio); 1085 } 1086 1087 /* 1088 * Completion of the cluster will also call biodone_chain(nbio). 1089 * We never call biodone(nbio) so we don't have to worry about 1090 * setting up a bio_done callback. It's handled in the sub-IO. 1091 */ 1092 /**/ 1093 } 1094 1095 /* 1096 * biodone callback 1097 * 1098 * No requirements. 1099 */ 1100 static void 1101 swap_chain_iodone(struct bio *biox) 1102 { 1103 struct buf **nextp; 1104 struct buf *bufx; /* chained sub-buffer */ 1105 struct bio *nbio; /* parent nbio with chain glue */ 1106 struct buf *bp; /* original bp associated with nbio */ 1107 int chain_empty; 1108 1109 bufx = biox->bio_buf; 1110 nbio = biox->bio_caller_info1.cluster_parent; 1111 bp = nbio->bio_buf; 1112 1113 /* 1114 * Update the original buffer 1115 */ 1116 KKASSERT(bp != NULL); 1117 if (bufx->b_flags & B_ERROR) { 1118 atomic_set_int(&bufx->b_flags, B_ERROR); 1119 bp->b_error = bufx->b_error; /* race ok */ 1120 } else if (bufx->b_resid != 0) { 1121 atomic_set_int(&bufx->b_flags, B_ERROR); 1122 bp->b_error = EINVAL; /* race ok */ 1123 } else { 1124 atomic_subtract_int(&bp->b_resid, bufx->b_bcount); 1125 } 1126 1127 /* 1128 * Remove us from the chain. 1129 */ 1130 spin_lock(&bp->b_lock.lk_spinlock); 1131 nextp = &nbio->bio_caller_info1.cluster_head; 1132 while (*nextp != bufx) { 1133 KKASSERT(*nextp != NULL); 1134 nextp = &(*nextp)->b_cluster_next; 1135 } 1136 *nextp = bufx->b_cluster_next; 1137 chain_empty = (nbio->bio_caller_info1.cluster_head == NULL); 1138 spin_unlock(&bp->b_lock.lk_spinlock); 1139 1140 /* 1141 * Clean up bufx. If the chain is now empty we finish out 1142 * the parent. Note that we may be racing other completions 1143 * so we must use the chain_empty status from above. 1144 */ 1145 if (chain_empty) { 1146 if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) { 1147 atomic_set_int(&bp->b_flags, B_ERROR); 1148 bp->b_error = EINVAL; 1149 } 1150 biodone_chain(nbio); 1151 } 1152 relpbuf(bufx, NULL); 1153 } 1154 1155 /* 1156 * SWAP_PAGER_GETPAGES() - bring page in from swap 1157 * 1158 * The requested page may have to be brought in from swap. Calculate the 1159 * swap block and bring in additional pages if possible. All pages must 1160 * have contiguous swap block assignments and reside in the same object. 1161 * 1162 * The caller has a single vm_object_pip_add() reference prior to 1163 * calling us and we should return with the same. 1164 * 1165 * The caller has BUSY'd the page. We should return with (*mpp) left busy, 1166 * and any additinal pages unbusied. 1167 * 1168 * If the caller encounters a PG_RAM page it will pass it to us even though 1169 * it may be valid and dirty. We cannot overwrite the page in this case! 1170 * The case is used to allow us to issue pure read-aheads. 1171 * 1172 * NOTE! XXX This code does not entirely pipeline yet due to the fact that 1173 * the PG_RAM page is validated at the same time as mreq. What we 1174 * really need to do is issue a separate read-ahead pbuf. 1175 * 1176 * No requirements. 1177 */ 1178 static int 1179 swap_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess) 1180 { 1181 struct buf *bp; 1182 struct bio *bio; 1183 vm_page_t mreq; 1184 vm_page_t m; 1185 vm_offset_t kva; 1186 swblk_t blk; 1187 int i; 1188 int j; 1189 int raonly; 1190 int error; 1191 u_int32_t flags; 1192 vm_page_t marray[XIO_INTERNAL_PAGES]; 1193 1194 mreq = *mpp; 1195 1196 vm_object_hold(object); 1197 if (mreq->object != object) { 1198 panic("swap_pager_getpages: object mismatch %p/%p", 1199 object, 1200 mreq->object 1201 ); 1202 } 1203 1204 /* 1205 * We don't want to overwrite a fully valid page as it might be 1206 * dirty. This case can occur when e.g. vm_fault hits a perfectly 1207 * valid page with PG_RAM set. 1208 * 1209 * In this case we see if the next page is a suitable page-in 1210 * candidate and if it is we issue read-ahead. PG_RAM will be 1211 * set on the last page of the read-ahead to continue the pipeline. 1212 */ 1213 if (mreq->valid == VM_PAGE_BITS_ALL) { 1214 if (swap_burst_read == 0 || mreq->pindex + 1 >= object->size) { 1215 vm_object_drop(object); 1216 return(VM_PAGER_OK); 1217 } 1218 blk = swp_pager_meta_ctl(object, mreq->pindex + 1, 0); 1219 if (blk == SWAPBLK_NONE) { 1220 vm_object_drop(object); 1221 return(VM_PAGER_OK); 1222 } 1223 m = vm_page_lookup_busy_try(object, mreq->pindex + 1, 1224 TRUE, &error); 1225 if (error) { 1226 vm_object_drop(object); 1227 return(VM_PAGER_OK); 1228 } else if (m == NULL) { 1229 /* 1230 * Use VM_ALLOC_QUICK to avoid blocking on cache 1231 * page reuse. 1232 */ 1233 m = vm_page_alloc(object, mreq->pindex + 1, 1234 VM_ALLOC_QUICK); 1235 if (m == NULL) { 1236 vm_object_drop(object); 1237 return(VM_PAGER_OK); 1238 } 1239 } else { 1240 if (m->valid) { 1241 vm_page_wakeup(m); 1242 vm_object_drop(object); 1243 return(VM_PAGER_OK); 1244 } 1245 vm_page_unqueue_nowakeup(m); 1246 } 1247 /* page is busy */ 1248 mreq = m; 1249 raonly = 1; 1250 } else { 1251 raonly = 0; 1252 } 1253 1254 /* 1255 * Try to block-read contiguous pages from swap if sequential, 1256 * otherwise just read one page. Contiguous pages from swap must 1257 * reside within a single device stripe because the I/O cannot be 1258 * broken up across multiple stripes. 1259 * 1260 * Note that blk and iblk can be SWAPBLK_NONE but the loop is 1261 * set up such that the case(s) are handled implicitly. 1262 */ 1263 blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0); 1264 marray[0] = mreq; 1265 1266 for (i = 1; swap_burst_read && 1267 i < XIO_INTERNAL_PAGES && 1268 mreq->pindex + i < object->size; ++i) { 1269 swblk_t iblk; 1270 1271 iblk = swp_pager_meta_ctl(object, mreq->pindex + i, 0); 1272 if (iblk != blk + i) 1273 break; 1274 if ((blk ^ iblk) & dmmax_mask) 1275 break; 1276 m = vm_page_lookup_busy_try(object, mreq->pindex + i, 1277 TRUE, &error); 1278 if (error) { 1279 break; 1280 } else if (m == NULL) { 1281 /* 1282 * Use VM_ALLOC_QUICK to avoid blocking on cache 1283 * page reuse. 1284 */ 1285 m = vm_page_alloc(object, mreq->pindex + i, 1286 VM_ALLOC_QUICK); 1287 if (m == NULL) 1288 break; 1289 } else { 1290 if (m->valid) { 1291 vm_page_wakeup(m); 1292 break; 1293 } 1294 vm_page_unqueue_nowakeup(m); 1295 } 1296 /* page is busy */ 1297 marray[i] = m; 1298 } 1299 if (i > 1) 1300 vm_page_flag_set(marray[i - 1], PG_RAM); 1301 1302 /* 1303 * If mreq is the requested page and we have nothing to do return 1304 * VM_PAGER_FAIL. If raonly is set mreq is just another read-ahead 1305 * page and must be cleaned up. 1306 */ 1307 if (blk == SWAPBLK_NONE) { 1308 KKASSERT(i == 1); 1309 if (raonly) { 1310 vnode_pager_freepage(mreq); 1311 vm_object_drop(object); 1312 return(VM_PAGER_OK); 1313 } else { 1314 vm_object_drop(object); 1315 return(VM_PAGER_FAIL); 1316 } 1317 } 1318 1319 /* 1320 * map our page(s) into kva for input 1321 */ 1322 bp = getpbuf_kva(&nsw_rcount); 1323 bio = &bp->b_bio1; 1324 kva = (vm_offset_t) bp->b_kvabase; 1325 bcopy(marray, bp->b_xio.xio_pages, i * sizeof(vm_page_t)); 1326 pmap_qenter(kva, bp->b_xio.xio_pages, i); 1327 1328 bp->b_data = (caddr_t)kva; 1329 bp->b_bcount = PAGE_SIZE * i; 1330 bp->b_xio.xio_npages = i; 1331 bio->bio_done = swp_pager_async_iodone; 1332 bio->bio_offset = (off_t)blk << PAGE_SHIFT; 1333 bio->bio_caller_info1.index = SWBIO_READ; 1334 1335 /* 1336 * Set index. If raonly set the index beyond the array so all 1337 * the pages are treated the same, otherwise the original mreq is 1338 * at index 0. 1339 */ 1340 if (raonly) 1341 bio->bio_driver_info = (void *)(intptr_t)i; 1342 else 1343 bio->bio_driver_info = (void *)(intptr_t)0; 1344 1345 for (j = 0; j < i; ++j) 1346 vm_page_flag_set(bp->b_xio.xio_pages[j], PG_SWAPINPROG); 1347 1348 mycpu->gd_cnt.v_swapin++; 1349 mycpu->gd_cnt.v_swappgsin += bp->b_xio.xio_npages; 1350 1351 /* 1352 * We still hold the lock on mreq, and our automatic completion routine 1353 * does not remove it. 1354 */ 1355 vm_object_pip_add(object, bp->b_xio.xio_npages); 1356 1357 /* 1358 * perform the I/O. NOTE!!! bp cannot be considered valid after 1359 * this point because we automatically release it on completion. 1360 * Instead, we look at the one page we are interested in which we 1361 * still hold a lock on even through the I/O completion. 1362 * 1363 * The other pages in our m[] array are also released on completion, 1364 * so we cannot assume they are valid anymore either. 1365 */ 1366 bp->b_cmd = BUF_CMD_READ; 1367 BUF_KERNPROC(bp); 1368 vn_strategy(swapdev_vp, bio); 1369 1370 /* 1371 * Wait for the page we want to complete. PG_SWAPINPROG is always 1372 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1373 * is set in the meta-data. 1374 * 1375 * If this is a read-ahead only we return immediately without 1376 * waiting for I/O. 1377 */ 1378 if (raonly) { 1379 vm_object_drop(object); 1380 return(VM_PAGER_OK); 1381 } 1382 1383 /* 1384 * Read-ahead includes originally requested page case. 1385 */ 1386 for (;;) { 1387 flags = mreq->flags; 1388 cpu_ccfence(); 1389 if ((flags & PG_SWAPINPROG) == 0) 1390 break; 1391 tsleep_interlock(mreq, 0); 1392 if (!atomic_cmpset_int(&mreq->flags, flags, 1393 flags | PG_WANTED | PG_REFERENCED)) { 1394 continue; 1395 } 1396 mycpu->gd_cnt.v_intrans++; 1397 if (tsleep(mreq, PINTERLOCKED, "swread", hz*20)) { 1398 kprintf( 1399 "swap_pager: indefinite wait buffer: " 1400 " offset: %lld, size: %ld\n", 1401 (long long)bio->bio_offset, 1402 (long)bp->b_bcount 1403 ); 1404 } 1405 } 1406 1407 /* 1408 * mreq is left bussied after completion, but all the other pages 1409 * are freed. If we had an unrecoverable read error the page will 1410 * not be valid. 1411 */ 1412 vm_object_drop(object); 1413 if (mreq->valid != VM_PAGE_BITS_ALL) 1414 return(VM_PAGER_ERROR); 1415 else 1416 return(VM_PAGER_OK); 1417 1418 /* 1419 * A final note: in a low swap situation, we cannot deallocate swap 1420 * and mark a page dirty here because the caller is likely to mark 1421 * the page clean when we return, causing the page to possibly revert 1422 * to all-zero's later. 1423 */ 1424 } 1425 1426 /* 1427 * swap_pager_putpages: 1428 * 1429 * Assign swap (if necessary) and initiate I/O on the specified pages. 1430 * 1431 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1432 * are automatically converted to SWAP objects. 1433 * 1434 * In a low memory situation we may block in vn_strategy(), but the new 1435 * vm_page reservation system coupled with properly written VFS devices 1436 * should ensure that no low-memory deadlock occurs. This is an area 1437 * which needs work. 1438 * 1439 * The parent has N vm_object_pip_add() references prior to 1440 * calling us and will remove references for rtvals[] that are 1441 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1442 * completion. 1443 * 1444 * The parent has soft-busy'd the pages it passes us and will unbusy 1445 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1446 * We need to unbusy the rest on I/O completion. 1447 * 1448 * No requirements. 1449 */ 1450 void 1451 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1452 boolean_t sync, int *rtvals) 1453 { 1454 int i; 1455 int n = 0; 1456 1457 vm_object_hold(object); 1458 1459 if (count && m[0]->object != object) { 1460 panic("swap_pager_getpages: object mismatch %p/%p", 1461 object, 1462 m[0]->object 1463 ); 1464 } 1465 1466 /* 1467 * Step 1 1468 * 1469 * Turn object into OBJT_SWAP 1470 * check for bogus sysops 1471 * force sync if not pageout process 1472 */ 1473 if (object->type == OBJT_DEFAULT) { 1474 if (object->type == OBJT_DEFAULT) 1475 swp_pager_meta_convert(object); 1476 } 1477 1478 if (curthread != pagethread) 1479 sync = TRUE; 1480 1481 /* 1482 * Step 2 1483 * 1484 * Update nsw parameters from swap_async_max sysctl values. 1485 * Do not let the sysop crash the machine with bogus numbers. 1486 */ 1487 1488 if (swap_async_max != nsw_wcount_async_max) { 1489 int n; 1490 1491 /* 1492 * limit range 1493 */ 1494 if ((n = swap_async_max) > nswbuf / 2) 1495 n = nswbuf / 2; 1496 if (n < 1) 1497 n = 1; 1498 swap_async_max = n; 1499 1500 /* 1501 * Adjust difference ( if possible ). If the current async 1502 * count is too low, we may not be able to make the adjustment 1503 * at this time. 1504 * 1505 * vm_token needed for nsw_wcount sleep interlock 1506 */ 1507 lwkt_gettoken(&vm_token); 1508 n -= nsw_wcount_async_max; 1509 if (nsw_wcount_async + n >= 0) { 1510 nsw_wcount_async += n; 1511 nsw_wcount_async_max += n; 1512 wakeup(&nsw_wcount_async); 1513 } 1514 lwkt_reltoken(&vm_token); 1515 } 1516 1517 /* 1518 * Step 3 1519 * 1520 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1521 * The page is left dirty until the pageout operation completes 1522 * successfully. 1523 */ 1524 1525 for (i = 0; i < count; i += n) { 1526 struct buf *bp; 1527 struct bio *bio; 1528 swblk_t blk; 1529 int j; 1530 1531 /* 1532 * Maximum I/O size is limited by a number of factors. 1533 */ 1534 1535 n = min(BLIST_MAX_ALLOC, count - i); 1536 n = min(n, nsw_cluster_max); 1537 1538 lwkt_gettoken(&vm_token); 1539 1540 /* 1541 * Get biggest block of swap we can. If we fail, fall 1542 * back and try to allocate a smaller block. Don't go 1543 * overboard trying to allocate space if it would overly 1544 * fragment swap. 1545 */ 1546 while ( 1547 (blk = swp_pager_getswapspace(object, n)) == SWAPBLK_NONE && 1548 n > 4 1549 ) { 1550 n >>= 1; 1551 } 1552 if (blk == SWAPBLK_NONE) { 1553 for (j = 0; j < n; ++j) 1554 rtvals[i+j] = VM_PAGER_FAIL; 1555 lwkt_reltoken(&vm_token); 1556 continue; 1557 } 1558 1559 /* 1560 * The I/O we are constructing cannot cross a physical 1561 * disk boundry in the swap stripe. Note: we are still 1562 * at splvm(). 1563 */ 1564 if ((blk ^ (blk + n)) & dmmax_mask) { 1565 j = ((blk + dmmax) & dmmax_mask) - blk; 1566 swp_pager_freeswapspace(object, blk + j, n - j); 1567 n = j; 1568 } 1569 1570 /* 1571 * All I/O parameters have been satisfied, build the I/O 1572 * request and assign the swap space. 1573 */ 1574 if (sync == TRUE) 1575 bp = getpbuf_kva(&nsw_wcount_sync); 1576 else 1577 bp = getpbuf_kva(&nsw_wcount_async); 1578 bio = &bp->b_bio1; 1579 1580 lwkt_reltoken(&vm_token); 1581 1582 pmap_qenter((vm_offset_t)bp->b_data, &m[i], n); 1583 1584 bp->b_bcount = PAGE_SIZE * n; 1585 bio->bio_offset = (off_t)blk << PAGE_SHIFT; 1586 1587 for (j = 0; j < n; ++j) { 1588 vm_page_t mreq = m[i+j]; 1589 1590 swp_pager_meta_build(mreq->object, mreq->pindex, 1591 blk + j); 1592 if (object->type == OBJT_SWAP) 1593 vm_page_dirty(mreq); 1594 rtvals[i+j] = VM_PAGER_OK; 1595 1596 vm_page_flag_set(mreq, PG_SWAPINPROG); 1597 bp->b_xio.xio_pages[j] = mreq; 1598 } 1599 bp->b_xio.xio_npages = n; 1600 1601 mycpu->gd_cnt.v_swapout++; 1602 mycpu->gd_cnt.v_swappgsout += bp->b_xio.xio_npages; 1603 1604 bp->b_dirtyoff = 0; /* req'd for NFS */ 1605 bp->b_dirtyend = bp->b_bcount; /* req'd for NFS */ 1606 bp->b_cmd = BUF_CMD_WRITE; 1607 bio->bio_caller_info1.index = SWBIO_WRITE; 1608 1609 /* 1610 * asynchronous 1611 */ 1612 if (sync == FALSE) { 1613 bio->bio_done = swp_pager_async_iodone; 1614 BUF_KERNPROC(bp); 1615 vn_strategy(swapdev_vp, bio); 1616 1617 for (j = 0; j < n; ++j) 1618 rtvals[i+j] = VM_PAGER_PEND; 1619 continue; 1620 } 1621 1622 /* 1623 * Issue synchrnously. 1624 * 1625 * Wait for the sync I/O to complete, then update rtvals. 1626 * We just set the rtvals[] to VM_PAGER_PEND so we can call 1627 * our async completion routine at the end, thus avoiding a 1628 * double-free. 1629 */ 1630 bio->bio_caller_info1.index |= SWBIO_SYNC; 1631 bio->bio_done = biodone_sync; 1632 bio->bio_flags |= BIO_SYNC; 1633 vn_strategy(swapdev_vp, bio); 1634 biowait(bio, "swwrt"); 1635 1636 for (j = 0; j < n; ++j) 1637 rtvals[i+j] = VM_PAGER_PEND; 1638 1639 /* 1640 * Now that we are through with the bp, we can call the 1641 * normal async completion, which frees everything up. 1642 */ 1643 swp_pager_async_iodone(bio); 1644 } 1645 vm_object_drop(object); 1646 } 1647 1648 /* 1649 * No requirements. 1650 */ 1651 void 1652 swap_pager_newswap(void) 1653 { 1654 swp_sizecheck(); 1655 } 1656 1657 /* 1658 * swp_pager_async_iodone: 1659 * 1660 * Completion routine for asynchronous reads and writes from/to swap. 1661 * Also called manually by synchronous code to finish up a bp. 1662 * 1663 * For READ operations, the pages are PG_BUSY'd. For WRITE operations, 1664 * the pages are vm_page_t->busy'd. For READ operations, we PG_BUSY 1665 * unbusy all pages except the 'main' request page. For WRITE 1666 * operations, we vm_page_t->busy'd unbusy all pages ( we can do this 1667 * because we marked them all VM_PAGER_PEND on return from putpages ). 1668 * 1669 * This routine may not block. 1670 * 1671 * No requirements. 1672 */ 1673 static void 1674 swp_pager_async_iodone(struct bio *bio) 1675 { 1676 struct buf *bp = bio->bio_buf; 1677 vm_object_t object = NULL; 1678 int i; 1679 int *nswptr; 1680 1681 /* 1682 * report error 1683 */ 1684 if (bp->b_flags & B_ERROR) { 1685 kprintf( 1686 "swap_pager: I/O error - %s failed; offset %lld," 1687 "size %ld, error %d\n", 1688 ((bio->bio_caller_info1.index & SWBIO_READ) ? 1689 "pagein" : "pageout"), 1690 (long long)bio->bio_offset, 1691 (long)bp->b_bcount, 1692 bp->b_error 1693 ); 1694 } 1695 1696 /* 1697 * set object, raise to splvm(). 1698 */ 1699 if (bp->b_xio.xio_npages) 1700 object = bp->b_xio.xio_pages[0]->object; 1701 1702 /* 1703 * remove the mapping for kernel virtual 1704 */ 1705 pmap_qremove((vm_offset_t)bp->b_data, bp->b_xio.xio_npages); 1706 1707 /* 1708 * cleanup pages. If an error occurs writing to swap, we are in 1709 * very serious trouble. If it happens to be a disk error, though, 1710 * we may be able to recover by reassigning the swap later on. So 1711 * in this case we remove the m->swapblk assignment for the page 1712 * but do not free it in the rlist. The errornous block(s) are thus 1713 * never reallocated as swap. Redirty the page and continue. 1714 */ 1715 for (i = 0; i < bp->b_xio.xio_npages; ++i) { 1716 vm_page_t m = bp->b_xio.xio_pages[i]; 1717 1718 if (bp->b_flags & B_ERROR) { 1719 /* 1720 * If an error occurs I'd love to throw the swapblk 1721 * away without freeing it back to swapspace, so it 1722 * can never be used again. But I can't from an 1723 * interrupt. 1724 */ 1725 1726 if (bio->bio_caller_info1.index & SWBIO_READ) { 1727 /* 1728 * When reading, reqpage needs to stay 1729 * locked for the parent, but all other 1730 * pages can be freed. We still want to 1731 * wakeup the parent waiting on the page, 1732 * though. ( also: pg_reqpage can be -1 and 1733 * not match anything ). 1734 * 1735 * We have to wake specifically requested pages 1736 * up too because we cleared PG_SWAPINPROG and 1737 * someone may be waiting for that. 1738 * 1739 * NOTE: for reads, m->dirty will probably 1740 * be overridden by the original caller of 1741 * getpages so don't play cute tricks here. 1742 * 1743 * NOTE: We can't actually free the page from 1744 * here, because this is an interrupt. It 1745 * is not legal to mess with object->memq 1746 * from an interrupt. Deactivate the page 1747 * instead. 1748 */ 1749 1750 m->valid = 0; 1751 vm_page_flag_clear(m, PG_ZERO); 1752 vm_page_flag_clear(m, PG_SWAPINPROG); 1753 1754 /* 1755 * bio_driver_info holds the requested page 1756 * index. 1757 */ 1758 if (i != (int)(intptr_t)bio->bio_driver_info) { 1759 vm_page_deactivate(m); 1760 vm_page_wakeup(m); 1761 } else { 1762 vm_page_flash(m); 1763 } 1764 /* 1765 * If i == bp->b_pager.pg_reqpage, do not wake 1766 * the page up. The caller needs to. 1767 */ 1768 } else { 1769 /* 1770 * If a write error occurs remove the swap 1771 * assignment (note that PG_SWAPPED may or 1772 * may not be set depending on prior activity). 1773 * 1774 * Re-dirty OBJT_SWAP pages as there is no 1775 * other backing store, we can't throw the 1776 * page away. 1777 * 1778 * Non-OBJT_SWAP pages (aka swapcache) must 1779 * not be dirtied since they may not have 1780 * been dirty in the first place, and they 1781 * do have backing store (the vnode). 1782 */ 1783 vm_page_busy_wait(m, FALSE, "swadpg"); 1784 swp_pager_meta_ctl(m->object, m->pindex, 1785 SWM_FREE); 1786 vm_page_flag_clear(m, PG_SWAPPED); 1787 if (m->object->type == OBJT_SWAP) { 1788 vm_page_dirty(m); 1789 vm_page_activate(m); 1790 } 1791 vm_page_flag_clear(m, PG_SWAPINPROG); 1792 vm_page_io_finish(m); 1793 vm_page_wakeup(m); 1794 } 1795 } else if (bio->bio_caller_info1.index & SWBIO_READ) { 1796 /* 1797 * NOTE: for reads, m->dirty will probably be 1798 * overridden by the original caller of getpages so 1799 * we cannot set them in order to free the underlying 1800 * swap in a low-swap situation. I don't think we'd 1801 * want to do that anyway, but it was an optimization 1802 * that existed in the old swapper for a time before 1803 * it got ripped out due to precisely this problem. 1804 * 1805 * clear PG_ZERO in page. 1806 * 1807 * If not the requested page then deactivate it. 1808 * 1809 * Note that the requested page, reqpage, is left 1810 * busied, but we still have to wake it up. The 1811 * other pages are released (unbusied) by 1812 * vm_page_wakeup(). We do not set reqpage's 1813 * valid bits here, it is up to the caller. 1814 */ 1815 1816 /* 1817 * NOTE: can't call pmap_clear_modify(m) from an 1818 * interrupt thread, the pmap code may have to map 1819 * non-kernel pmaps and currently asserts the case. 1820 */ 1821 /*pmap_clear_modify(m);*/ 1822 m->valid = VM_PAGE_BITS_ALL; 1823 vm_page_undirty(m); 1824 vm_page_flag_clear(m, PG_ZERO | PG_SWAPINPROG); 1825 vm_page_flag_set(m, PG_SWAPPED); 1826 1827 /* 1828 * We have to wake specifically requested pages 1829 * up too because we cleared PG_SWAPINPROG and 1830 * could be waiting for it in getpages. However, 1831 * be sure to not unbusy getpages specifically 1832 * requested page - getpages expects it to be 1833 * left busy. 1834 * 1835 * bio_driver_info holds the requested page 1836 */ 1837 if (i != (int)(intptr_t)bio->bio_driver_info) { 1838 vm_page_deactivate(m); 1839 vm_page_wakeup(m); 1840 } else { 1841 vm_page_flash(m); 1842 } 1843 } else { 1844 /* 1845 * Mark the page clean but do not mess with the 1846 * pmap-layer's modified state. That state should 1847 * also be clear since the caller protected the 1848 * page VM_PROT_READ, but allow the case. 1849 * 1850 * We are in an interrupt, avoid pmap operations. 1851 * 1852 * If we have a severe page deficit, deactivate the 1853 * page. Do not try to cache it (which would also 1854 * involve a pmap op), because the page might still 1855 * be read-heavy. 1856 * 1857 * When using the swap to cache clean vnode pages 1858 * we do not mess with the page dirty bits. 1859 */ 1860 vm_page_busy_wait(m, FALSE, "swadpg"); 1861 if (m->object->type == OBJT_SWAP) 1862 vm_page_undirty(m); 1863 vm_page_flag_clear(m, PG_SWAPINPROG); 1864 vm_page_flag_set(m, PG_SWAPPED); 1865 if (vm_page_count_severe()) 1866 vm_page_deactivate(m); 1867 #if 0 1868 if (!vm_page_count_severe() || !vm_page_try_to_cache(m)) 1869 vm_page_protect(m, VM_PROT_READ); 1870 #endif 1871 vm_page_io_finish(m); 1872 vm_page_wakeup(m); 1873 } 1874 } 1875 1876 /* 1877 * adjust pip. NOTE: the original parent may still have its own 1878 * pip refs on the object. 1879 */ 1880 1881 if (object) 1882 vm_object_pip_wakeup_n(object, bp->b_xio.xio_npages); 1883 1884 /* 1885 * Release the physical I/O buffer. 1886 * 1887 * NOTE: Due to synchronous operations in the write case b_cmd may 1888 * already be set to BUF_CMD_DONE and BIO_SYNC may have already 1889 * been cleared. 1890 * 1891 * Use vm_token to interlock nsw_rcount/wcount wakeup? 1892 */ 1893 lwkt_gettoken(&vm_token); 1894 if (bio->bio_caller_info1.index & SWBIO_READ) 1895 nswptr = &nsw_rcount; 1896 else if (bio->bio_caller_info1.index & SWBIO_SYNC) 1897 nswptr = &nsw_wcount_sync; 1898 else 1899 nswptr = &nsw_wcount_async; 1900 bp->b_cmd = BUF_CMD_DONE; 1901 relpbuf(bp, nswptr); 1902 lwkt_reltoken(&vm_token); 1903 } 1904 1905 /* 1906 * Fault-in a potentially swapped page and remove the swap reference. 1907 * 1908 * object must be held. 1909 */ 1910 static __inline void 1911 swp_pager_fault_page(vm_object_t object, vm_pindex_t pindex) 1912 { 1913 struct vnode *vp; 1914 vm_page_t m; 1915 int error; 1916 1917 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 1918 1919 if (object->type == OBJT_VNODE) { 1920 /* 1921 * Any swap related to a vnode is due to swapcache. We must 1922 * vget() the vnode in case it is not active (otherwise 1923 * vref() will panic). Calling vm_object_page_remove() will 1924 * ensure that any swap ref is removed interlocked with the 1925 * page. clean_only is set to TRUE so we don't throw away 1926 * dirty pages. 1927 */ 1928 vp = object->handle; 1929 error = vget(vp, LK_SHARED | LK_RETRY | LK_CANRECURSE); 1930 if (error == 0) { 1931 vm_object_page_remove(object, pindex, pindex + 1, TRUE); 1932 vput(vp); 1933 } 1934 } else { 1935 /* 1936 * Otherwise it is a normal OBJT_SWAP object and we can 1937 * fault the page in and remove the swap. 1938 */ 1939 m = vm_fault_object_page(object, IDX_TO_OFF(pindex), 1940 VM_PROT_NONE, 1941 VM_FAULT_DIRTY | VM_FAULT_UNSWAP, 1942 &error); 1943 if (m) 1944 vm_page_unhold(m); 1945 } 1946 } 1947 1948 int 1949 swap_pager_swapoff(int devidx) 1950 { 1951 vm_object_t object; 1952 struct swblock *swap; 1953 swblk_t v; 1954 int i; 1955 1956 lwkt_gettoken(&vmobj_token); 1957 rescan: 1958 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1959 if (object->type != OBJT_SWAP && object->type != OBJT_VNODE) 1960 continue; 1961 vm_object_hold(object); 1962 if (object->type == OBJT_SWAP || object->type == OBJT_VNODE) { 1963 RB_FOREACH(swap, 1964 swblock_rb_tree, &object->swblock_root) { 1965 for (i = 0; i < SWAP_META_PAGES; ++i) { 1966 v = swap->swb_pages[i]; 1967 if (v != SWAPBLK_NONE && 1968 BLK2DEVIDX(v) == devidx) { 1969 swp_pager_fault_page( 1970 object, 1971 swap->swb_index + i); 1972 vm_object_drop(object); 1973 goto rescan; 1974 } 1975 } 1976 } 1977 } 1978 vm_object_drop(object); 1979 } 1980 lwkt_reltoken(&vmobj_token); 1981 1982 /* 1983 * If we fail to locate all swblocks we just fail gracefully and 1984 * do not bother to restore paging on the swap device. If the 1985 * user wants to retry the user can retry. 1986 */ 1987 if (swdevt[devidx].sw_nused) 1988 return (1); 1989 else 1990 return (0); 1991 } 1992 1993 /************************************************************************ 1994 * SWAP META DATA * 1995 ************************************************************************ 1996 * 1997 * These routines manipulate the swap metadata stored in the 1998 * OBJT_SWAP object. All swp_*() routines must be called at 1999 * splvm() because swap can be freed up by the low level vm_page 2000 * code which might be called from interrupts beyond what splbio() covers. 2001 * 2002 * Swap metadata is implemented with a global hash and not directly 2003 * linked into the object. Instead the object simply contains 2004 * appropriate tracking counters. 2005 */ 2006 2007 /* 2008 * Lookup the swblock containing the specified swap block index. 2009 * 2010 * The caller must hold the object. 2011 */ 2012 static __inline 2013 struct swblock * 2014 swp_pager_lookup(vm_object_t object, vm_pindex_t index) 2015 { 2016 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 2017 index &= ~SWAP_META_MASK; 2018 return (RB_LOOKUP(swblock_rb_tree, &object->swblock_root, index)); 2019 } 2020 2021 /* 2022 * Remove a swblock from the RB tree. 2023 * 2024 * The caller must hold the object. 2025 */ 2026 static __inline 2027 void 2028 swp_pager_remove(vm_object_t object, struct swblock *swap) 2029 { 2030 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 2031 RB_REMOVE(swblock_rb_tree, &object->swblock_root, swap); 2032 } 2033 2034 /* 2035 * Convert default object to swap object if necessary 2036 * 2037 * The caller must hold the object. 2038 */ 2039 static void 2040 swp_pager_meta_convert(vm_object_t object) 2041 { 2042 if (object->type == OBJT_DEFAULT) { 2043 object->type = OBJT_SWAP; 2044 KKASSERT(object->swblock_count == 0); 2045 } 2046 } 2047 2048 /* 2049 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 2050 * 2051 * We first convert the object to a swap object if it is a default 2052 * object. Vnode objects do not need to be converted. 2053 * 2054 * The specified swapblk is added to the object's swap metadata. If 2055 * the swapblk is not valid, it is freed instead. Any previously 2056 * assigned swapblk is freed. 2057 * 2058 * The caller must hold the object. 2059 */ 2060 static void 2061 swp_pager_meta_build(vm_object_t object, vm_pindex_t index, swblk_t swapblk) 2062 { 2063 struct swblock *swap; 2064 struct swblock *oswap; 2065 2066 KKASSERT(swapblk != SWAPBLK_NONE); 2067 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 2068 2069 /* 2070 * Convert object if necessary 2071 */ 2072 if (object->type == OBJT_DEFAULT) 2073 swp_pager_meta_convert(object); 2074 2075 /* 2076 * Locate swblock. If not found create, but if we aren't adding 2077 * anything just return. If we run out of space in the map we wait 2078 * and, since the hash table may have changed, retry. 2079 */ 2080 retry: 2081 swap = swp_pager_lookup(object, index); 2082 2083 if (swap == NULL) { 2084 int i; 2085 2086 swap = zalloc(swap_zone); 2087 if (swap == NULL) { 2088 vm_wait(0); 2089 goto retry; 2090 } 2091 swap->swb_index = index & ~SWAP_META_MASK; 2092 swap->swb_count = 0; 2093 2094 ++object->swblock_count; 2095 2096 for (i = 0; i < SWAP_META_PAGES; ++i) 2097 swap->swb_pages[i] = SWAPBLK_NONE; 2098 oswap = RB_INSERT(swblock_rb_tree, &object->swblock_root, swap); 2099 KKASSERT(oswap == NULL); 2100 } 2101 2102 /* 2103 * Delete prior contents of metadata 2104 */ 2105 2106 index &= SWAP_META_MASK; 2107 2108 if (swap->swb_pages[index] != SWAPBLK_NONE) { 2109 swp_pager_freeswapspace(object, swap->swb_pages[index], 1); 2110 --swap->swb_count; 2111 } 2112 2113 /* 2114 * Enter block into metadata 2115 */ 2116 swap->swb_pages[index] = swapblk; 2117 if (swapblk != SWAPBLK_NONE) 2118 ++swap->swb_count; 2119 } 2120 2121 /* 2122 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2123 * 2124 * The requested range of blocks is freed, with any associated swap 2125 * returned to the swap bitmap. 2126 * 2127 * This routine will free swap metadata structures as they are cleaned 2128 * out. This routine does *NOT* operate on swap metadata associated 2129 * with resident pages. 2130 * 2131 * The caller must hold the object. 2132 */ 2133 static int swp_pager_meta_free_callback(struct swblock *swb, void *data); 2134 2135 static void 2136 swp_pager_meta_free(vm_object_t object, vm_pindex_t index, vm_pindex_t count) 2137 { 2138 struct swfreeinfo info; 2139 2140 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 2141 2142 /* 2143 * Nothing to do 2144 */ 2145 if (object->swblock_count == 0) { 2146 KKASSERT(RB_EMPTY(&object->swblock_root)); 2147 return; 2148 } 2149 if (count == 0) 2150 return; 2151 2152 /* 2153 * Setup for RB tree scan. Note that the pindex range can be huge 2154 * due to the 64 bit page index space so we cannot safely iterate. 2155 */ 2156 info.object = object; 2157 info.basei = index & ~SWAP_META_MASK; 2158 info.begi = index; 2159 info.endi = index + count - 1; 2160 swblock_rb_tree_RB_SCAN(&object->swblock_root, rb_swblock_scancmp, 2161 swp_pager_meta_free_callback, &info); 2162 } 2163 2164 /* 2165 * The caller must hold the object. 2166 */ 2167 static 2168 int 2169 swp_pager_meta_free_callback(struct swblock *swap, void *data) 2170 { 2171 struct swfreeinfo *info = data; 2172 vm_object_t object = info->object; 2173 int index; 2174 int eindex; 2175 2176 /* 2177 * Figure out the range within the swblock. The wider scan may 2178 * return edge-case swap blocks when the start and/or end points 2179 * are in the middle of a block. 2180 */ 2181 if (swap->swb_index < info->begi) 2182 index = (int)info->begi & SWAP_META_MASK; 2183 else 2184 index = 0; 2185 2186 if (swap->swb_index + SWAP_META_PAGES > info->endi) 2187 eindex = (int)info->endi & SWAP_META_MASK; 2188 else 2189 eindex = SWAP_META_MASK; 2190 2191 /* 2192 * Scan and free the blocks. The loop terminates early 2193 * if (swap) runs out of blocks and could be freed. 2194 */ 2195 while (index <= eindex) { 2196 swblk_t v = swap->swb_pages[index]; 2197 2198 if (v != SWAPBLK_NONE) { 2199 swap->swb_pages[index] = SWAPBLK_NONE; 2200 if (--swap->swb_count == 0) { 2201 swp_pager_remove(object, swap); 2202 zfree(swap_zone, swap); 2203 --object->swblock_count; 2204 break; 2205 } 2206 swp_pager_freeswapspace(object, v, 1); /* can block */ 2207 } 2208 ++index; 2209 } 2210 /* swap may be invalid here due to zfree above */ 2211 return(0); 2212 } 2213 2214 /* 2215 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2216 * 2217 * This routine locates and destroys all swap metadata associated with 2218 * an object. 2219 * 2220 * The caller must hold the object. 2221 */ 2222 static void 2223 swp_pager_meta_free_all(vm_object_t object) 2224 { 2225 struct swblock *swap; 2226 int i; 2227 2228 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 2229 2230 while ((swap = RB_ROOT(&object->swblock_root)) != NULL) { 2231 swp_pager_remove(object, swap); 2232 for (i = 0; i < SWAP_META_PAGES; ++i) { 2233 swblk_t v = swap->swb_pages[i]; 2234 if (v != SWAPBLK_NONE) { 2235 --swap->swb_count; 2236 swp_pager_freeswapspace(object, v, 1); 2237 } 2238 } 2239 if (swap->swb_count != 0) 2240 panic("swap_pager_meta_free_all: swb_count != 0"); 2241 zfree(swap_zone, swap); 2242 --object->swblock_count; 2243 } 2244 KKASSERT(object->swblock_count == 0); 2245 } 2246 2247 /* 2248 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. 2249 * 2250 * This routine is capable of looking up, popping, or freeing 2251 * swapblk assignments in the swap meta data or in the vm_page_t. 2252 * The routine typically returns the swapblk being looked-up, or popped, 2253 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block 2254 * was invalid. This routine will automatically free any invalid 2255 * meta-data swapblks. 2256 * 2257 * It is not possible to store invalid swapblks in the swap meta data 2258 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking. 2259 * 2260 * When acting on a busy resident page and paging is in progress, we 2261 * have to wait until paging is complete but otherwise can act on the 2262 * busy page. 2263 * 2264 * SWM_FREE remove and free swap block from metadata 2265 * SWM_POP remove from meta data but do not free.. pop it out 2266 * 2267 * The caller must hold the object. 2268 */ 2269 static swblk_t 2270 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t index, int flags) 2271 { 2272 struct swblock *swap; 2273 swblk_t r1; 2274 2275 if (object->swblock_count == 0) 2276 return(SWAPBLK_NONE); 2277 2278 r1 = SWAPBLK_NONE; 2279 swap = swp_pager_lookup(object, index); 2280 2281 if (swap != NULL) { 2282 index &= SWAP_META_MASK; 2283 r1 = swap->swb_pages[index]; 2284 2285 if (r1 != SWAPBLK_NONE) { 2286 if (flags & (SWM_FREE|SWM_POP)) { 2287 swap->swb_pages[index] = SWAPBLK_NONE; 2288 if (--swap->swb_count == 0) { 2289 swp_pager_remove(object, swap); 2290 zfree(swap_zone, swap); 2291 --object->swblock_count; 2292 } 2293 } 2294 if (flags & SWM_FREE) { 2295 swp_pager_freeswapspace(object, r1, 1); 2296 r1 = SWAPBLK_NONE; 2297 } 2298 } 2299 } 2300 return(r1); 2301 } 2302