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 lwkt_gettoken(&vm_token); 427 object = vm_object_allocate(OBJT_DEFAULT, 428 OFF_TO_IDX(offset + PAGE_MASK + size)); 429 swp_pager_meta_convert(object); 430 lwkt_reltoken(&vm_token); 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 lwkt_gettoken(&vm_token); 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 crit_enter(); 459 swp_pager_meta_free_all(object); 460 crit_exit(); 461 lwkt_reltoken(&vm_token); 462 } 463 464 /************************************************************************ 465 * SWAP PAGER BITMAP ROUTINES * 466 ************************************************************************/ 467 468 /* 469 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 470 * 471 * Allocate swap for the requested number of pages. The starting 472 * swap block number (a page index) is returned or SWAPBLK_NONE 473 * if the allocation failed. 474 * 475 * Also has the side effect of advising that somebody made a mistake 476 * when they configured swap and didn't configure enough. 477 * 478 * The caller must hold vm_token. 479 * This routine may not block. 480 * 481 * NOTE: vm_token must be held to avoid races with bitmap frees from 482 * vm_page_remove() via swap_pager_page_removed(). 483 */ 484 static __inline swblk_t 485 swp_pager_getswapspace(vm_object_t object, int npages) 486 { 487 swblk_t blk; 488 489 ASSERT_LWKT_TOKEN_HELD(&vm_token); 490 491 if ((blk = blist_alloc(swapblist, npages)) == SWAPBLK_NONE) { 492 if (swap_pager_full != 2) { 493 kprintf("swap_pager_getswapspace: failed\n"); 494 swap_pager_full = 2; 495 swap_pager_almost_full = 1; 496 } 497 } else { 498 swapacctspace(blk, -npages); 499 if (object->type == OBJT_SWAP) 500 vm_swap_anon_use += npages; 501 else 502 vm_swap_cache_use += npages; 503 swp_sizecheck(); 504 } 505 return(blk); 506 } 507 508 /* 509 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 510 * 511 * This routine returns the specified swap blocks back to the bitmap. 512 * 513 * Note: This routine may not block (it could in the old swap code), 514 * and through the use of the new blist routines it does not block. 515 * 516 * We must be called at splvm() to avoid races with bitmap frees from 517 * vm_page_remove() aka swap_pager_page_removed(). 518 * 519 * The caller must hold vm_token. 520 * This routine may not block. 521 */ 522 523 static __inline void 524 swp_pager_freeswapspace(vm_object_t object, swblk_t blk, int npages) 525 { 526 struct swdevt *sp = &swdevt[BLK2DEVIDX(blk)]; 527 528 sp->sw_nused -= npages; 529 if (object->type == OBJT_SWAP) 530 vm_swap_anon_use -= npages; 531 else 532 vm_swap_cache_use -= npages; 533 534 if (sp->sw_flags & SW_CLOSING) 535 return; 536 537 blist_free(swapblist, blk, npages); 538 vm_swap_size += npages; 539 swp_sizecheck(); 540 } 541 542 /* 543 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 544 * range within an object. 545 * 546 * This is a globally accessible routine. 547 * 548 * This routine removes swapblk assignments from swap metadata. 549 * 550 * The external callers of this routine typically have already destroyed 551 * or renamed vm_page_t's associated with this range in the object so 552 * we should be ok. 553 * 554 * No requirements. 555 */ 556 void 557 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_pindex_t size) 558 { 559 crit_enter(); 560 lwkt_gettoken(&vm_token); 561 swp_pager_meta_free(object, start, size); 562 lwkt_reltoken(&vm_token); 563 crit_exit(); 564 } 565 566 /* 567 * No requirements. 568 */ 569 void 570 swap_pager_freespace_all(vm_object_t object) 571 { 572 crit_enter(); 573 lwkt_gettoken(&vm_token); 574 swp_pager_meta_free_all(object); 575 lwkt_reltoken(&vm_token); 576 crit_exit(); 577 } 578 579 /* 580 * This function conditionally frees swap cache swap starting at 581 * (*basei) in the object. (count) swap blocks will be nominally freed. 582 * The actual number of blocks freed can be more or less than the 583 * requested number. 584 * 585 * This function nominally returns the number of blocks freed. However, 586 * the actual number of blocks freed may be less then the returned value. 587 * If the function is unable to exhaust the object or if it is able to 588 * free (approximately) the requested number of blocks it returns 589 * a value n > count. 590 * 591 * If we exhaust the object we will return a value n <= count. 592 * 593 * The caller must hold vm_token. 594 * 595 * WARNING! If count == 0 then -1 can be returned as a degenerate case, 596 * callers should always pass a count value > 0. 597 */ 598 static int swap_pager_condfree_callback(struct swblock *swap, void *data); 599 600 int 601 swap_pager_condfree(vm_object_t object, vm_pindex_t *basei, int count) 602 { 603 struct swfreeinfo info; 604 605 ASSERT_LWKT_TOKEN_HELD(&vm_token); 606 607 info.object = object; 608 info.basei = *basei; /* skip up to this page index */ 609 info.begi = count; /* max swap pages to destroy */ 610 info.endi = count * 8; /* max swblocks to scan */ 611 612 swblock_rb_tree_RB_SCAN(&object->swblock_root, rb_swblock_condcmp, 613 swap_pager_condfree_callback, &info); 614 *basei = info.basei; 615 if (info.endi < 0 && info.begi <= count) 616 info.begi = count + 1; 617 return(count - (int)info.begi); 618 } 619 620 /* 621 * The idea is to free whole meta-block to avoid fragmenting 622 * the swap space or disk I/O. We only do this if NO VM pages 623 * are present. 624 * 625 * We do not have to deal with clearing PG_SWAPPED in related VM 626 * pages because there are no related VM pages. 627 * 628 * The caller must hold vm_token. 629 */ 630 static int 631 swap_pager_condfree_callback(struct swblock *swap, void *data) 632 { 633 struct swfreeinfo *info = data; 634 vm_object_t object = info->object; 635 int i; 636 637 for (i = 0; i < SWAP_META_PAGES; ++i) { 638 if (vm_page_lookup(object, swap->swb_index + i)) 639 break; 640 } 641 info->basei = swap->swb_index + SWAP_META_PAGES; 642 if (i == SWAP_META_PAGES) { 643 info->begi -= swap->swb_count; 644 swap_pager_freespace(object, swap->swb_index, SWAP_META_PAGES); 645 } 646 --info->endi; 647 if ((int)info->begi < 0 || (int)info->endi < 0) 648 return(-1); 649 return(0); 650 } 651 652 /* 653 * Called by vm_page_alloc() when a new VM page is inserted 654 * into a VM object. Checks whether swap has been assigned to 655 * the page and sets PG_SWAPPED as necessary. 656 * 657 * No requirements. 658 */ 659 void 660 swap_pager_page_inserted(vm_page_t m) 661 { 662 if (m->object->swblock_count) { 663 crit_enter(); 664 lwkt_gettoken(&vm_token); 665 if (swp_pager_meta_ctl(m->object, m->pindex, 0) != SWAPBLK_NONE) 666 vm_page_flag_set(m, PG_SWAPPED); 667 lwkt_reltoken(&vm_token); 668 crit_exit(); 669 } 670 } 671 672 /* 673 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 674 * 675 * Assigns swap blocks to the specified range within the object. The 676 * swap blocks are not zerod. Any previous swap assignment is destroyed. 677 * 678 * Returns 0 on success, -1 on failure. 679 * 680 * The caller is responsible for avoiding races in the specified range. 681 * No other requirements. 682 */ 683 int 684 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 685 { 686 int n = 0; 687 swblk_t blk = SWAPBLK_NONE; 688 vm_pindex_t beg = start; /* save start index */ 689 690 crit_enter(); 691 lwkt_gettoken(&vm_token); 692 while (size) { 693 if (n == 0) { 694 n = BLIST_MAX_ALLOC; 695 while ((blk = swp_pager_getswapspace(object, n)) == 696 SWAPBLK_NONE) 697 { 698 n >>= 1; 699 if (n == 0) { 700 swp_pager_meta_free(object, beg, 701 start - beg); 702 lwkt_reltoken(&vm_token); 703 crit_exit(); 704 return(-1); 705 } 706 } 707 } 708 swp_pager_meta_build(object, start, blk); 709 --size; 710 ++start; 711 ++blk; 712 --n; 713 } 714 swp_pager_meta_free(object, start, n); 715 lwkt_reltoken(&vm_token); 716 crit_exit(); 717 return(0); 718 } 719 720 /* 721 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 722 * and destroy the source. 723 * 724 * Copy any valid swapblks from the source to the destination. In 725 * cases where both the source and destination have a valid swapblk, 726 * we keep the destination's. 727 * 728 * This routine is allowed to block. It may block allocating metadata 729 * indirectly through swp_pager_meta_build() or if paging is still in 730 * progress on the source. 731 * 732 * This routine can be called at any spl 733 * 734 * XXX vm_page_collapse() kinda expects us not to block because we 735 * supposedly do not need to allocate memory, but for the moment we 736 * *may* have to get a little memory from the zone allocator, but 737 * it is taken from the interrupt memory. We should be ok. 738 * 739 * The source object contains no vm_page_t's (which is just as well) 740 * 741 * The source object is of type OBJT_SWAP. 742 * 743 * The source and destination objects must be locked or 744 * inaccessible (XXX are they ?) 745 * 746 * The caller must hold vm_token. 747 */ 748 void 749 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 750 vm_pindex_t base_index, int destroysource) 751 { 752 vm_pindex_t i; 753 754 ASSERT_LWKT_TOKEN_HELD(&vm_token); 755 crit_enter(); 756 757 /* 758 * transfer source to destination. 759 */ 760 for (i = 0; i < dstobject->size; ++i) { 761 swblk_t dstaddr; 762 763 /* 764 * Locate (without changing) the swapblk on the destination, 765 * unless it is invalid in which case free it silently, or 766 * if the destination is a resident page, in which case the 767 * source is thrown away. 768 */ 769 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 770 771 if (dstaddr == SWAPBLK_NONE) { 772 /* 773 * Destination has no swapblk and is not resident, 774 * copy source. 775 */ 776 swblk_t srcaddr; 777 778 srcaddr = swp_pager_meta_ctl(srcobject, 779 base_index + i, SWM_POP); 780 781 if (srcaddr != SWAPBLK_NONE) 782 swp_pager_meta_build(dstobject, i, srcaddr); 783 } else { 784 /* 785 * Destination has valid swapblk or it is represented 786 * by a resident page. We destroy the sourceblock. 787 */ 788 swp_pager_meta_ctl(srcobject, base_index + i, SWM_FREE); 789 } 790 } 791 792 /* 793 * Free left over swap blocks in source. 794 * 795 * We have to revert the type to OBJT_DEFAULT so we do not accidently 796 * double-remove the object from the swap queues. 797 */ 798 if (destroysource) { 799 /* 800 * Reverting the type is not necessary, the caller is going 801 * to destroy srcobject directly, but I'm doing it here 802 * for consistency since we've removed the object from its 803 * queues. 804 */ 805 swp_pager_meta_free_all(srcobject); 806 if (srcobject->type == OBJT_SWAP) 807 srcobject->type = OBJT_DEFAULT; 808 } 809 crit_exit(); 810 } 811 812 /* 813 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 814 * the requested page. 815 * 816 * We determine whether good backing store exists for the requested 817 * page and return TRUE if it does, FALSE if it doesn't. 818 * 819 * If TRUE, we also try to determine how much valid, contiguous backing 820 * store exists before and after the requested page within a reasonable 821 * distance. We do not try to restrict it to the swap device stripe 822 * (that is handled in getpages/putpages). It probably isn't worth 823 * doing here. 824 * 825 * No requirements. 826 */ 827 boolean_t 828 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex) 829 { 830 swblk_t blk0; 831 832 /* 833 * do we have good backing store at the requested index ? 834 */ 835 836 crit_enter(); 837 lwkt_gettoken(&vm_token); 838 blk0 = swp_pager_meta_ctl(object, pindex, 0); 839 840 if (blk0 == SWAPBLK_NONE) { 841 lwkt_reltoken(&vm_token); 842 crit_exit(); 843 return (FALSE); 844 } 845 lwkt_reltoken(&vm_token); 846 crit_exit(); 847 return (TRUE); 848 } 849 850 /* 851 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 852 * 853 * This removes any associated swap backing store, whether valid or 854 * not, from the page. This operates on any VM object, not just OBJT_SWAP 855 * objects. 856 * 857 * This routine is typically called when a page is made dirty, at 858 * which point any associated swap can be freed. MADV_FREE also 859 * calls us in a special-case situation 860 * 861 * NOTE!!! If the page is clean and the swap was valid, the caller 862 * should make the page dirty before calling this routine. This routine 863 * does NOT change the m->dirty status of the page. Also: MADV_FREE 864 * depends on it. 865 * 866 * The page must be busied or soft-busied. 867 * The caller must hold vm_token if the caller does not wish to block here. 868 * No other requirements. 869 */ 870 void 871 swap_pager_unswapped(vm_page_t m) 872 { 873 if (m->flags & PG_SWAPPED) { 874 crit_enter(); 875 lwkt_gettoken(&vm_token); 876 KKASSERT(m->flags & PG_SWAPPED); 877 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); 878 vm_page_flag_clear(m, PG_SWAPPED); 879 lwkt_reltoken(&vm_token); 880 crit_exit(); 881 } 882 } 883 884 /* 885 * SWAP_PAGER_STRATEGY() - read, write, free blocks 886 * 887 * This implements a VM OBJECT strategy function using swap backing store. 888 * This can operate on any VM OBJECT type, not necessarily just OBJT_SWAP 889 * types. 890 * 891 * This is intended to be a cacheless interface (i.e. caching occurs at 892 * higher levels), and is also used as a swap-based SSD cache for vnode 893 * and device objects. 894 * 895 * All I/O goes directly to and from the swap device. 896 * 897 * We currently attempt to run I/O synchronously or asynchronously as 898 * the caller requests. This isn't perfect because we loose error 899 * sequencing when we run multiple ops in parallel to satisfy a request. 900 * But this is swap, so we let it all hang out. 901 * 902 * No requirements. 903 */ 904 void 905 swap_pager_strategy(vm_object_t object, struct bio *bio) 906 { 907 struct buf *bp = bio->bio_buf; 908 struct bio *nbio; 909 vm_pindex_t start; 910 vm_pindex_t biox_blkno = 0; 911 int count; 912 char *data; 913 struct bio *biox; 914 struct buf *bufx; 915 struct bio_track *track; 916 917 /* 918 * tracking for swapdev vnode I/Os 919 */ 920 if (bp->b_cmd == BUF_CMD_READ) 921 track = &swapdev_vp->v_track_read; 922 else 923 track = &swapdev_vp->v_track_write; 924 925 if (bp->b_bcount & PAGE_MASK) { 926 bp->b_error = EINVAL; 927 bp->b_flags |= B_ERROR | B_INVAL; 928 biodone(bio); 929 kprintf("swap_pager_strategy: bp %p offset %lld size %d, " 930 "not page bounded\n", 931 bp, (long long)bio->bio_offset, (int)bp->b_bcount); 932 return; 933 } 934 935 /* 936 * Clear error indication, initialize page index, count, data pointer. 937 */ 938 bp->b_error = 0; 939 bp->b_flags &= ~B_ERROR; 940 bp->b_resid = bp->b_bcount; 941 942 start = (vm_pindex_t)(bio->bio_offset >> PAGE_SHIFT); 943 count = howmany(bp->b_bcount, PAGE_SIZE); 944 data = bp->b_data; 945 946 /* 947 * Deal with BUF_CMD_FREEBLKS 948 */ 949 if (bp->b_cmd == BUF_CMD_FREEBLKS) { 950 /* 951 * FREE PAGE(s) - destroy underlying swap that is no longer 952 * needed. 953 */ 954 crit_enter(); 955 lwkt_gettoken(&vm_token); 956 swp_pager_meta_free(object, start, count); 957 lwkt_reltoken(&vm_token); 958 crit_exit(); 959 bp->b_resid = 0; 960 biodone(bio); 961 return; 962 } 963 964 /* 965 * We need to be able to create a new cluster of I/O's. We cannot 966 * use the caller fields of the passed bio so push a new one. 967 * 968 * Because nbio is just a placeholder for the cluster links, 969 * we can biodone() the original bio instead of nbio to make 970 * things a bit more efficient. 971 */ 972 nbio = push_bio(bio); 973 nbio->bio_offset = bio->bio_offset; 974 nbio->bio_caller_info1.cluster_head = NULL; 975 nbio->bio_caller_info2.cluster_tail = NULL; 976 977 biox = NULL; 978 bufx = NULL; 979 980 /* 981 * Execute read or write 982 */ 983 crit_enter(); 984 lwkt_gettoken(&vm_token); 985 while (count > 0) { 986 swblk_t blk; 987 988 /* 989 * Obtain block. If block not found and writing, allocate a 990 * new block and build it into the object. 991 */ 992 blk = swp_pager_meta_ctl(object, start, 0); 993 if ((blk == SWAPBLK_NONE) && bp->b_cmd != BUF_CMD_READ) { 994 blk = swp_pager_getswapspace(object, 1); 995 if (blk == SWAPBLK_NONE) { 996 bp->b_error = ENOMEM; 997 bp->b_flags |= B_ERROR; 998 break; 999 } 1000 swp_pager_meta_build(object, start, blk); 1001 } 1002 1003 /* 1004 * Do we have to flush our current collection? Yes if: 1005 * 1006 * - no swap block at this index 1007 * - swap block is not contiguous 1008 * - we cross a physical disk boundry in the 1009 * stripe. 1010 */ 1011 if ( 1012 biox && (biox_blkno + btoc(bufx->b_bcount) != blk || 1013 ((biox_blkno ^ blk) & dmmax_mask) 1014 ) 1015 ) { 1016 if (bp->b_cmd == BUF_CMD_READ) { 1017 ++mycpu->gd_cnt.v_swapin; 1018 mycpu->gd_cnt.v_swappgsin += btoc(bufx->b_bcount); 1019 } else { 1020 ++mycpu->gd_cnt.v_swapout; 1021 mycpu->gd_cnt.v_swappgsout += btoc(bufx->b_bcount); 1022 bufx->b_dirtyend = bufx->b_bcount; 1023 } 1024 1025 /* 1026 * Finished with this buf. 1027 */ 1028 KKASSERT(bufx->b_bcount != 0); 1029 if (bufx->b_cmd != BUF_CMD_READ) 1030 bufx->b_dirtyend = bufx->b_bcount; 1031 biox = NULL; 1032 bufx = NULL; 1033 } 1034 1035 /* 1036 * Add new swapblk to biox, instantiating biox if necessary. 1037 * Zero-fill reads are able to take a shortcut. 1038 */ 1039 if (blk == SWAPBLK_NONE) { 1040 /* 1041 * We can only get here if we are reading. Since 1042 * we are at splvm() we can safely modify b_resid, 1043 * even if chain ops are in progress. 1044 */ 1045 bzero(data, PAGE_SIZE); 1046 bp->b_resid -= PAGE_SIZE; 1047 } else { 1048 if (biox == NULL) { 1049 /* XXX chain count > 4, wait to <= 4 */ 1050 1051 bufx = getpbuf(NULL); 1052 biox = &bufx->b_bio1; 1053 cluster_append(nbio, bufx); 1054 bufx->b_flags |= (bufx->b_flags & B_ORDERED); 1055 bufx->b_cmd = bp->b_cmd; 1056 biox->bio_done = swap_chain_iodone; 1057 biox->bio_offset = (off_t)blk << PAGE_SHIFT; 1058 biox->bio_caller_info1.cluster_parent = nbio; 1059 biox_blkno = blk; 1060 bufx->b_bcount = 0; 1061 bufx->b_data = data; 1062 } 1063 bufx->b_bcount += PAGE_SIZE; 1064 } 1065 --count; 1066 ++start; 1067 data += PAGE_SIZE; 1068 } 1069 lwkt_reltoken(&vm_token); 1070 crit_exit(); 1071 1072 /* 1073 * Flush out last buffer 1074 */ 1075 if (biox) { 1076 if (bufx->b_cmd == BUF_CMD_READ) { 1077 ++mycpu->gd_cnt.v_swapin; 1078 mycpu->gd_cnt.v_swappgsin += btoc(bufx->b_bcount); 1079 } else { 1080 ++mycpu->gd_cnt.v_swapout; 1081 mycpu->gd_cnt.v_swappgsout += btoc(bufx->b_bcount); 1082 bufx->b_dirtyend = bufx->b_bcount; 1083 } 1084 KKASSERT(bufx->b_bcount); 1085 if (bufx->b_cmd != BUF_CMD_READ) 1086 bufx->b_dirtyend = bufx->b_bcount; 1087 /* biox, bufx = NULL */ 1088 } 1089 1090 /* 1091 * Now initiate all the I/O. Be careful looping on our chain as 1092 * I/O's may complete while we are still initiating them. 1093 * 1094 * If the request is a 100% sparse read no bios will be present 1095 * and we just biodone() the buffer. 1096 */ 1097 nbio->bio_caller_info2.cluster_tail = NULL; 1098 bufx = nbio->bio_caller_info1.cluster_head; 1099 1100 if (bufx) { 1101 while (bufx) { 1102 biox = &bufx->b_bio1; 1103 BUF_KERNPROC(bufx); 1104 bufx = bufx->b_cluster_next; 1105 vn_strategy(swapdev_vp, biox); 1106 } 1107 } else { 1108 biodone(bio); 1109 } 1110 1111 /* 1112 * Completion of the cluster will also call biodone_chain(nbio). 1113 * We never call biodone(nbio) so we don't have to worry about 1114 * setting up a bio_done callback. It's handled in the sub-IO. 1115 */ 1116 /**/ 1117 } 1118 1119 /* 1120 * biodone callback 1121 * 1122 * No requirements. 1123 */ 1124 static void 1125 swap_chain_iodone(struct bio *biox) 1126 { 1127 struct buf **nextp; 1128 struct buf *bufx; /* chained sub-buffer */ 1129 struct bio *nbio; /* parent nbio with chain glue */ 1130 struct buf *bp; /* original bp associated with nbio */ 1131 int chain_empty; 1132 1133 bufx = biox->bio_buf; 1134 nbio = biox->bio_caller_info1.cluster_parent; 1135 bp = nbio->bio_buf; 1136 1137 /* 1138 * Update the original buffer 1139 */ 1140 KKASSERT(bp != NULL); 1141 if (bufx->b_flags & B_ERROR) { 1142 atomic_set_int(&bufx->b_flags, B_ERROR); 1143 bp->b_error = bufx->b_error; /* race ok */ 1144 } else if (bufx->b_resid != 0) { 1145 atomic_set_int(&bufx->b_flags, B_ERROR); 1146 bp->b_error = EINVAL; /* race ok */ 1147 } else { 1148 atomic_subtract_int(&bp->b_resid, bufx->b_bcount); 1149 } 1150 1151 /* 1152 * Remove us from the chain. 1153 */ 1154 spin_lock(&bp->b_lock.lk_spinlock); 1155 nextp = &nbio->bio_caller_info1.cluster_head; 1156 while (*nextp != bufx) { 1157 KKASSERT(*nextp != NULL); 1158 nextp = &(*nextp)->b_cluster_next; 1159 } 1160 *nextp = bufx->b_cluster_next; 1161 chain_empty = (nbio->bio_caller_info1.cluster_head == NULL); 1162 spin_unlock(&bp->b_lock.lk_spinlock); 1163 1164 /* 1165 * Clean up bufx. If the chain is now empty we finish out 1166 * the parent. Note that we may be racing other completions 1167 * so we must use the chain_empty status from above. 1168 */ 1169 if (chain_empty) { 1170 if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) { 1171 atomic_set_int(&bp->b_flags, B_ERROR); 1172 bp->b_error = EINVAL; 1173 } 1174 biodone_chain(nbio); 1175 } 1176 relpbuf(bufx, NULL); 1177 } 1178 1179 /* 1180 * SWAP_PAGER_GETPAGES() - bring page in from swap 1181 * 1182 * The requested page may have to be brought in from swap. Calculate the 1183 * swap block and bring in additional pages if possible. All pages must 1184 * have contiguous swap block assignments and reside in the same object. 1185 * 1186 * The caller has a single vm_object_pip_add() reference prior to 1187 * calling us and we should return with the same. 1188 * 1189 * The caller has BUSY'd the page. We should return with (*mpp) left busy, 1190 * and any additinal pages unbusied. 1191 * 1192 * If the caller encounters a PG_RAM page it will pass it to us even though 1193 * it may be valid and dirty. We cannot overwrite the page in this case! 1194 * The case is used to allow us to issue pure read-aheads. 1195 * 1196 * NOTE! XXX This code does not entirely pipeline yet due to the fact that 1197 * the PG_RAM page is validated at the same time as mreq. What we 1198 * really need to do is issue a separate read-ahead pbuf. 1199 * 1200 * No requirements. 1201 */ 1202 static int 1203 swap_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess) 1204 { 1205 struct buf *bp; 1206 struct bio *bio; 1207 vm_page_t mreq; 1208 vm_page_t m; 1209 vm_offset_t kva; 1210 swblk_t blk; 1211 int i; 1212 int j; 1213 int raonly; 1214 vm_page_t marray[XIO_INTERNAL_PAGES]; 1215 1216 mreq = *mpp; 1217 1218 if (mreq->object != object) { 1219 panic("swap_pager_getpages: object mismatch %p/%p", 1220 object, 1221 mreq->object 1222 ); 1223 } 1224 1225 /* 1226 * We don't want to overwrite a fully valid page as it might be 1227 * dirty. This case can occur when e.g. vm_fault hits a perfectly 1228 * valid page with PG_RAM set. 1229 * 1230 * In this case we see if the next page is a suitable page-in 1231 * candidate and if it is we issue read-ahead. PG_RAM will be 1232 * set on the last page of the read-ahead to continue the pipeline. 1233 */ 1234 if (mreq->valid == VM_PAGE_BITS_ALL) { 1235 if (swap_burst_read == 0 || mreq->pindex + 1 >= object->size) 1236 return(VM_PAGER_OK); 1237 crit_enter(); 1238 lwkt_gettoken(&vm_token); 1239 blk = swp_pager_meta_ctl(object, mreq->pindex + 1, 0); 1240 if (blk == SWAPBLK_NONE) { 1241 lwkt_reltoken(&vm_token); 1242 crit_exit(); 1243 return(VM_PAGER_OK); 1244 } 1245 m = vm_page_lookup(object, mreq->pindex + 1); 1246 if (m == NULL) { 1247 m = vm_page_alloc(object, mreq->pindex + 1, 1248 VM_ALLOC_QUICK); 1249 if (m == NULL) { 1250 lwkt_reltoken(&vm_token); 1251 crit_exit(); 1252 return(VM_PAGER_OK); 1253 } 1254 } else { 1255 if ((m->flags & PG_BUSY) || m->busy || m->valid) { 1256 lwkt_reltoken(&vm_token); 1257 crit_exit(); 1258 return(VM_PAGER_OK); 1259 } 1260 vm_page_unqueue_nowakeup(m); 1261 vm_page_busy(m); 1262 } 1263 mreq = m; 1264 raonly = 1; 1265 lwkt_reltoken(&vm_token); 1266 crit_exit(); 1267 } else { 1268 raonly = 0; 1269 } 1270 1271 /* 1272 * Try to block-read contiguous pages from swap if sequential, 1273 * otherwise just read one page. Contiguous pages from swap must 1274 * reside within a single device stripe because the I/O cannot be 1275 * broken up across multiple stripes. 1276 * 1277 * Note that blk and iblk can be SWAPBLK_NONE but the loop is 1278 * set up such that the case(s) are handled implicitly. 1279 */ 1280 crit_enter(); 1281 lwkt_gettoken(&vm_token); 1282 blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0); 1283 marray[0] = mreq; 1284 1285 for (i = 1; swap_burst_read && 1286 i < XIO_INTERNAL_PAGES && 1287 mreq->pindex + i < object->size; ++i) { 1288 swblk_t iblk; 1289 1290 iblk = swp_pager_meta_ctl(object, mreq->pindex + i, 0); 1291 if (iblk != blk + i) 1292 break; 1293 if ((blk ^ iblk) & dmmax_mask) 1294 break; 1295 m = vm_page_lookup(object, mreq->pindex + i); 1296 if (m == NULL) { 1297 m = vm_page_alloc(object, mreq->pindex + i, 1298 VM_ALLOC_QUICK); 1299 if (m == NULL) 1300 break; 1301 } else { 1302 if ((m->flags & PG_BUSY) || m->busy || m->valid) 1303 break; 1304 vm_page_unqueue_nowakeup(m); 1305 vm_page_busy(m); 1306 } 1307 marray[i] = m; 1308 } 1309 if (i > 1) 1310 vm_page_flag_set(marray[i - 1], PG_RAM); 1311 1312 lwkt_reltoken(&vm_token); 1313 crit_exit(); 1314 1315 /* 1316 * If mreq is the requested page and we have nothing to do return 1317 * VM_PAGER_FAIL. If raonly is set mreq is just another read-ahead 1318 * page and must be cleaned up. 1319 */ 1320 if (blk == SWAPBLK_NONE) { 1321 KKASSERT(i == 1); 1322 if (raonly) { 1323 vnode_pager_freepage(mreq); 1324 return(VM_PAGER_OK); 1325 } else { 1326 return(VM_PAGER_FAIL); 1327 } 1328 } 1329 1330 /* 1331 * map our page(s) into kva for input 1332 */ 1333 bp = getpbuf_kva(&nsw_rcount); 1334 bio = &bp->b_bio1; 1335 kva = (vm_offset_t) bp->b_kvabase; 1336 bcopy(marray, bp->b_xio.xio_pages, i * sizeof(vm_page_t)); 1337 pmap_qenter(kva, bp->b_xio.xio_pages, i); 1338 1339 bp->b_data = (caddr_t)kva; 1340 bp->b_bcount = PAGE_SIZE * i; 1341 bp->b_xio.xio_npages = i; 1342 bio->bio_done = swp_pager_async_iodone; 1343 bio->bio_offset = (off_t)blk << PAGE_SHIFT; 1344 bio->bio_caller_info1.index = SWBIO_READ; 1345 1346 /* 1347 * Set index. If raonly set the index beyond the array so all 1348 * the pages are treated the same, otherwise the original mreq is 1349 * at index 0. 1350 */ 1351 if (raonly) 1352 bio->bio_driver_info = (void *)(intptr_t)i; 1353 else 1354 bio->bio_driver_info = (void *)(intptr_t)0; 1355 1356 for (j = 0; j < i; ++j) 1357 vm_page_flag_set(bp->b_xio.xio_pages[j], PG_SWAPINPROG); 1358 1359 mycpu->gd_cnt.v_swapin++; 1360 mycpu->gd_cnt.v_swappgsin += bp->b_xio.xio_npages; 1361 1362 /* 1363 * We still hold the lock on mreq, and our automatic completion routine 1364 * does not remove it. 1365 */ 1366 vm_object_pip_add(object, bp->b_xio.xio_npages); 1367 1368 /* 1369 * perform the I/O. NOTE!!! bp cannot be considered valid after 1370 * this point because we automatically release it on completion. 1371 * Instead, we look at the one page we are interested in which we 1372 * still hold a lock on even through the I/O completion. 1373 * 1374 * The other pages in our m[] array are also released on completion, 1375 * so we cannot assume they are valid anymore either. 1376 */ 1377 bp->b_cmd = BUF_CMD_READ; 1378 BUF_KERNPROC(bp); 1379 vn_strategy(swapdev_vp, bio); 1380 1381 /* 1382 * Wait for the page we want to complete. PG_SWAPINPROG is always 1383 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1384 * is set in the meta-data. 1385 * 1386 * If this is a read-ahead only we return immediately without 1387 * waiting for I/O. 1388 */ 1389 if (raonly) 1390 return(VM_PAGER_OK); 1391 1392 /* 1393 * Read-ahead includes originally requested page case. 1394 */ 1395 crit_enter(); 1396 lwkt_gettoken(&vm_token); 1397 while ((mreq->flags & PG_SWAPINPROG) != 0) { 1398 vm_page_flag_set(mreq, PG_WANTED | PG_REFERENCED); 1399 mycpu->gd_cnt.v_intrans++; 1400 if (tsleep(mreq, 0, "swread", hz*20)) { 1401 kprintf( 1402 "swap_pager: indefinite wait buffer: " 1403 " offset: %lld, size: %ld\n", 1404 (long long)bio->bio_offset, 1405 (long)bp->b_bcount 1406 ); 1407 } 1408 } 1409 lwkt_reltoken(&vm_token); 1410 crit_exit(); 1411 1412 /* 1413 * mreq is left bussied after completion, but all the other pages 1414 * are freed. If we had an unrecoverable read error the page will 1415 * not be valid. 1416 */ 1417 if (mreq->valid != VM_PAGE_BITS_ALL) 1418 return(VM_PAGER_ERROR); 1419 else 1420 return(VM_PAGER_OK); 1421 1422 /* 1423 * A final note: in a low swap situation, we cannot deallocate swap 1424 * and mark a page dirty here because the caller is likely to mark 1425 * the page clean when we return, causing the page to possibly revert 1426 * to all-zero's later. 1427 */ 1428 } 1429 1430 /* 1431 * swap_pager_putpages: 1432 * 1433 * Assign swap (if necessary) and initiate I/O on the specified pages. 1434 * 1435 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1436 * are automatically converted to SWAP objects. 1437 * 1438 * In a low memory situation we may block in vn_strategy(), but the new 1439 * vm_page reservation system coupled with properly written VFS devices 1440 * should ensure that no low-memory deadlock occurs. This is an area 1441 * which needs work. 1442 * 1443 * The parent has N vm_object_pip_add() references prior to 1444 * calling us and will remove references for rtvals[] that are 1445 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1446 * completion. 1447 * 1448 * The parent has soft-busy'd the pages it passes us and will unbusy 1449 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1450 * We need to unbusy the rest on I/O completion. 1451 * 1452 * No requirements. 1453 */ 1454 void 1455 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1456 boolean_t sync, int *rtvals) 1457 { 1458 int i; 1459 int n = 0; 1460 1461 if (count && m[0]->object != object) { 1462 panic("swap_pager_getpages: object mismatch %p/%p", 1463 object, 1464 m[0]->object 1465 ); 1466 } 1467 1468 /* 1469 * Step 1 1470 * 1471 * Turn object into OBJT_SWAP 1472 * check for bogus sysops 1473 * force sync if not pageout process 1474 */ 1475 if (object->type == OBJT_DEFAULT) { 1476 lwkt_gettoken(&vm_token); 1477 if (object->type == OBJT_DEFAULT) 1478 swp_pager_meta_convert(object); 1479 lwkt_reltoken(&vm_token); 1480 } 1481 1482 if (curthread != pagethread) 1483 sync = TRUE; 1484 1485 /* 1486 * Step 2 1487 * 1488 * Update nsw parameters from swap_async_max sysctl values. 1489 * Do not let the sysop crash the machine with bogus numbers. 1490 */ 1491 1492 if (swap_async_max != nsw_wcount_async_max) { 1493 int n; 1494 1495 /* 1496 * limit range 1497 */ 1498 if ((n = swap_async_max) > nswbuf / 2) 1499 n = nswbuf / 2; 1500 if (n < 1) 1501 n = 1; 1502 swap_async_max = n; 1503 1504 /* 1505 * Adjust difference ( if possible ). If the current async 1506 * count is too low, we may not be able to make the adjustment 1507 * at this time. 1508 */ 1509 crit_enter(); 1510 lwkt_gettoken(&vm_token); 1511 n -= nsw_wcount_async_max; 1512 if (nsw_wcount_async + n >= 0) { 1513 nsw_wcount_async += n; 1514 nsw_wcount_async_max += n; 1515 wakeup(&nsw_wcount_async); 1516 } 1517 lwkt_reltoken(&vm_token); 1518 crit_exit(); 1519 } 1520 1521 /* 1522 * Step 3 1523 * 1524 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1525 * The page is left dirty until the pageout operation completes 1526 * successfully. 1527 */ 1528 1529 for (i = 0; i < count; i += n) { 1530 struct buf *bp; 1531 struct bio *bio; 1532 swblk_t blk; 1533 int j; 1534 1535 /* 1536 * Maximum I/O size is limited by a number of factors. 1537 */ 1538 1539 n = min(BLIST_MAX_ALLOC, count - i); 1540 n = min(n, nsw_cluster_max); 1541 1542 crit_enter(); 1543 lwkt_gettoken(&vm_token); 1544 1545 /* 1546 * Get biggest block of swap we can. If we fail, fall 1547 * back and try to allocate a smaller block. Don't go 1548 * overboard trying to allocate space if it would overly 1549 * fragment swap. 1550 */ 1551 while ( 1552 (blk = swp_pager_getswapspace(object, n)) == SWAPBLK_NONE && 1553 n > 4 1554 ) { 1555 n >>= 1; 1556 } 1557 if (blk == SWAPBLK_NONE) { 1558 for (j = 0; j < n; ++j) 1559 rtvals[i+j] = VM_PAGER_FAIL; 1560 lwkt_reltoken(&vm_token); 1561 crit_exit(); 1562 continue; 1563 } 1564 1565 /* 1566 * The I/O we are constructing cannot cross a physical 1567 * disk boundry in the swap stripe. Note: we are still 1568 * at splvm(). 1569 */ 1570 if ((blk ^ (blk + n)) & dmmax_mask) { 1571 j = ((blk + dmmax) & dmmax_mask) - blk; 1572 swp_pager_freeswapspace(object, blk + j, n - j); 1573 n = j; 1574 } 1575 1576 /* 1577 * All I/O parameters have been satisfied, build the I/O 1578 * request and assign the swap space. 1579 */ 1580 if (sync == TRUE) 1581 bp = getpbuf_kva(&nsw_wcount_sync); 1582 else 1583 bp = getpbuf_kva(&nsw_wcount_async); 1584 bio = &bp->b_bio1; 1585 1586 pmap_qenter((vm_offset_t)bp->b_data, &m[i], n); 1587 1588 bp->b_bcount = PAGE_SIZE * n; 1589 bio->bio_offset = (off_t)blk << PAGE_SHIFT; 1590 1591 for (j = 0; j < n; ++j) { 1592 vm_page_t mreq = m[i+j]; 1593 1594 swp_pager_meta_build(mreq->object, mreq->pindex, 1595 blk + j); 1596 if (object->type == OBJT_SWAP) 1597 vm_page_dirty(mreq); 1598 rtvals[i+j] = VM_PAGER_OK; 1599 1600 vm_page_flag_set(mreq, PG_SWAPINPROG); 1601 bp->b_xio.xio_pages[j] = mreq; 1602 } 1603 bp->b_xio.xio_npages = n; 1604 1605 mycpu->gd_cnt.v_swapout++; 1606 mycpu->gd_cnt.v_swappgsout += bp->b_xio.xio_npages; 1607 1608 lwkt_reltoken(&vm_token); 1609 crit_exit(); 1610 1611 bp->b_dirtyoff = 0; /* req'd for NFS */ 1612 bp->b_dirtyend = bp->b_bcount; /* req'd for NFS */ 1613 bp->b_cmd = BUF_CMD_WRITE; 1614 bio->bio_caller_info1.index = SWBIO_WRITE; 1615 1616 /* 1617 * asynchronous 1618 */ 1619 if (sync == FALSE) { 1620 bio->bio_done = swp_pager_async_iodone; 1621 BUF_KERNPROC(bp); 1622 vn_strategy(swapdev_vp, bio); 1623 1624 for (j = 0; j < n; ++j) 1625 rtvals[i+j] = VM_PAGER_PEND; 1626 continue; 1627 } 1628 1629 /* 1630 * Issue synchrnously. 1631 * 1632 * Wait for the sync I/O to complete, then update rtvals. 1633 * We just set the rtvals[] to VM_PAGER_PEND so we can call 1634 * our async completion routine at the end, thus avoiding a 1635 * double-free. 1636 */ 1637 bio->bio_caller_info1.index |= SWBIO_SYNC; 1638 bio->bio_done = biodone_sync; 1639 bio->bio_flags |= BIO_SYNC; 1640 vn_strategy(swapdev_vp, bio); 1641 biowait(bio, "swwrt"); 1642 1643 for (j = 0; j < n; ++j) 1644 rtvals[i+j] = VM_PAGER_PEND; 1645 1646 /* 1647 * Now that we are through with the bp, we can call the 1648 * normal async completion, which frees everything up. 1649 */ 1650 swp_pager_async_iodone(bio); 1651 } 1652 } 1653 1654 /* 1655 * No requirements. 1656 */ 1657 void 1658 swap_pager_newswap(void) 1659 { 1660 swp_sizecheck(); 1661 } 1662 1663 /* 1664 * swp_pager_async_iodone: 1665 * 1666 * Completion routine for asynchronous reads and writes from/to swap. 1667 * Also called manually by synchronous code to finish up a bp. 1668 * 1669 * For READ operations, the pages are PG_BUSY'd. For WRITE operations, 1670 * the pages are vm_page_t->busy'd. For READ operations, we PG_BUSY 1671 * unbusy all pages except the 'main' request page. For WRITE 1672 * operations, we vm_page_t->busy'd unbusy all pages ( we can do this 1673 * because we marked them all VM_PAGER_PEND on return from putpages ). 1674 * 1675 * This routine may not block. 1676 * 1677 * No requirements. 1678 */ 1679 static void 1680 swp_pager_async_iodone(struct bio *bio) 1681 { 1682 struct buf *bp = bio->bio_buf; 1683 vm_object_t object = NULL; 1684 int i; 1685 int *nswptr; 1686 1687 /* 1688 * report error 1689 */ 1690 if (bp->b_flags & B_ERROR) { 1691 kprintf( 1692 "swap_pager: I/O error - %s failed; offset %lld," 1693 "size %ld, error %d\n", 1694 ((bio->bio_caller_info1.index & SWBIO_READ) ? 1695 "pagein" : "pageout"), 1696 (long long)bio->bio_offset, 1697 (long)bp->b_bcount, 1698 bp->b_error 1699 ); 1700 } 1701 1702 /* 1703 * set object, raise to splvm(). 1704 */ 1705 if (bp->b_xio.xio_npages) 1706 object = bp->b_xio.xio_pages[0]->object; 1707 crit_enter(); 1708 lwkt_gettoken(&vm_token); 1709 1710 /* 1711 * remove the mapping for kernel virtual 1712 */ 1713 pmap_qremove((vm_offset_t)bp->b_data, bp->b_xio.xio_npages); 1714 1715 /* 1716 * cleanup pages. If an error occurs writing to swap, we are in 1717 * very serious trouble. If it happens to be a disk error, though, 1718 * we may be able to recover by reassigning the swap later on. So 1719 * in this case we remove the m->swapblk assignment for the page 1720 * but do not free it in the rlist. The errornous block(s) are thus 1721 * never reallocated as swap. Redirty the page and continue. 1722 */ 1723 for (i = 0; i < bp->b_xio.xio_npages; ++i) { 1724 vm_page_t m = bp->b_xio.xio_pages[i]; 1725 1726 if (bp->b_flags & B_ERROR) { 1727 /* 1728 * If an error occurs I'd love to throw the swapblk 1729 * away without freeing it back to swapspace, so it 1730 * can never be used again. But I can't from an 1731 * interrupt. 1732 */ 1733 1734 if (bio->bio_caller_info1.index & SWBIO_READ) { 1735 /* 1736 * When reading, reqpage needs to stay 1737 * locked for the parent, but all other 1738 * pages can be freed. We still want to 1739 * wakeup the parent waiting on the page, 1740 * though. ( also: pg_reqpage can be -1 and 1741 * not match anything ). 1742 * 1743 * We have to wake specifically requested pages 1744 * up too because we cleared PG_SWAPINPROG and 1745 * someone may be waiting for that. 1746 * 1747 * NOTE: for reads, m->dirty will probably 1748 * be overridden by the original caller of 1749 * getpages so don't play cute tricks here. 1750 * 1751 * NOTE: We can't actually free the page from 1752 * here, because this is an interrupt. It 1753 * is not legal to mess with object->memq 1754 * from an interrupt. Deactivate the page 1755 * instead. 1756 */ 1757 1758 m->valid = 0; 1759 vm_page_flag_clear(m, PG_ZERO); 1760 vm_page_flag_clear(m, PG_SWAPINPROG); 1761 1762 /* 1763 * bio_driver_info holds the requested page 1764 * index. 1765 */ 1766 if (i != (int)(intptr_t)bio->bio_driver_info) { 1767 vm_page_deactivate(m); 1768 vm_page_wakeup(m); 1769 } else { 1770 vm_page_flash(m); 1771 } 1772 /* 1773 * If i == bp->b_pager.pg_reqpage, do not wake 1774 * the page up. The caller needs to. 1775 */ 1776 } else { 1777 /* 1778 * If a write error occurs remove the swap 1779 * assignment (note that PG_SWAPPED may or 1780 * may not be set depending on prior activity). 1781 * 1782 * Re-dirty OBJT_SWAP pages as there is no 1783 * other backing store, we can't throw the 1784 * page away. 1785 * 1786 * Non-OBJT_SWAP pages (aka swapcache) must 1787 * not be dirtied since they may not have 1788 * been dirty in the first place, and they 1789 * do have backing store (the vnode). 1790 */ 1791 swp_pager_meta_ctl(m->object, m->pindex, 1792 SWM_FREE); 1793 vm_page_flag_clear(m, PG_SWAPPED); 1794 if (m->object->type == OBJT_SWAP) { 1795 vm_page_dirty(m); 1796 vm_page_activate(m); 1797 } 1798 vm_page_flag_clear(m, PG_SWAPINPROG); 1799 vm_page_io_finish(m); 1800 } 1801 } else if (bio->bio_caller_info1.index & SWBIO_READ) { 1802 /* 1803 * NOTE: for reads, m->dirty will probably be 1804 * overridden by the original caller of getpages so 1805 * we cannot set them in order to free the underlying 1806 * swap in a low-swap situation. I don't think we'd 1807 * want to do that anyway, but it was an optimization 1808 * that existed in the old swapper for a time before 1809 * it got ripped out due to precisely this problem. 1810 * 1811 * clear PG_ZERO in page. 1812 * 1813 * If not the requested page then deactivate it. 1814 * 1815 * Note that the requested page, reqpage, is left 1816 * busied, but we still have to wake it up. The 1817 * other pages are released (unbusied) by 1818 * vm_page_wakeup(). We do not set reqpage's 1819 * valid bits here, it is up to the caller. 1820 */ 1821 1822 /* 1823 * NOTE: can't call pmap_clear_modify(m) from an 1824 * interrupt thread, the pmap code may have to map 1825 * non-kernel pmaps and currently asserts the case. 1826 */ 1827 /*pmap_clear_modify(m);*/ 1828 m->valid = VM_PAGE_BITS_ALL; 1829 vm_page_undirty(m); 1830 vm_page_flag_clear(m, PG_ZERO | PG_SWAPINPROG); 1831 vm_page_flag_set(m, PG_SWAPPED); 1832 1833 /* 1834 * We have to wake specifically requested pages 1835 * up too because we cleared PG_SWAPINPROG and 1836 * could be waiting for it in getpages. However, 1837 * be sure to not unbusy getpages specifically 1838 * requested page - getpages expects it to be 1839 * left busy. 1840 * 1841 * bio_driver_info holds the requested page 1842 */ 1843 if (i != (int)(intptr_t)bio->bio_driver_info) { 1844 vm_page_deactivate(m); 1845 vm_page_wakeup(m); 1846 } else { 1847 vm_page_flash(m); 1848 } 1849 } else { 1850 /* 1851 * Mark the page clean but do not mess with the 1852 * pmap-layer's modified state. That state should 1853 * also be clear since the caller protected the 1854 * page VM_PROT_READ, but allow the case. 1855 * 1856 * We are in an interrupt, avoid pmap operations. 1857 * 1858 * If we have a severe page deficit, deactivate the 1859 * page. Do not try to cache it (which would also 1860 * involve a pmap op), because the page might still 1861 * be read-heavy. 1862 * 1863 * When using the swap to cache clean vnode pages 1864 * we do not mess with the page dirty bits. 1865 */ 1866 if (m->object->type == OBJT_SWAP) 1867 vm_page_undirty(m); 1868 vm_page_flag_clear(m, PG_SWAPINPROG); 1869 vm_page_flag_set(m, PG_SWAPPED); 1870 if (vm_page_count_severe()) 1871 vm_page_deactivate(m); 1872 #if 0 1873 if (!vm_page_count_severe() || !vm_page_try_to_cache(m)) 1874 vm_page_protect(m, VM_PROT_READ); 1875 #endif 1876 vm_page_io_finish(m); 1877 } 1878 } 1879 1880 /* 1881 * adjust pip. NOTE: the original parent may still have its own 1882 * pip refs on the object. 1883 */ 1884 1885 if (object) 1886 vm_object_pip_wakeupn(object, bp->b_xio.xio_npages); 1887 1888 /* 1889 * Release the physical I/O buffer. 1890 * 1891 * NOTE: Due to synchronous operations in the write case b_cmd may 1892 * already be set to BUF_CMD_DONE and BIO_SYNC may have already 1893 * been cleared. 1894 */ 1895 if (bio->bio_caller_info1.index & SWBIO_READ) 1896 nswptr = &nsw_rcount; 1897 else if (bio->bio_caller_info1.index & SWBIO_SYNC) 1898 nswptr = &nsw_wcount_sync; 1899 else 1900 nswptr = &nsw_wcount_async; 1901 bp->b_cmd = BUF_CMD_DONE; 1902 relpbuf(bp, nswptr); 1903 lwkt_reltoken(&vm_token); 1904 crit_exit(); 1905 } 1906 1907 /* 1908 * Fault-in a potentially swapped page and remove the swap reference. 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 if (object->type == OBJT_VNODE) { 1918 /* 1919 * Any swap related to a vnode is due to swapcache. We must 1920 * vget() the vnode in case it is not active (otherwise 1921 * vref() will panic). Calling vm_object_page_remove() will 1922 * ensure that any swap ref is removed interlocked with the 1923 * page. clean_only is set to TRUE so we don't throw away 1924 * dirty pages. 1925 */ 1926 vp = object->handle; 1927 error = vget(vp, LK_SHARED | LK_RETRY | LK_CANRECURSE); 1928 if (error == 0) { 1929 vm_object_page_remove(object, pindex, pindex + 1, TRUE); 1930 vput(vp); 1931 } 1932 } else { 1933 /* 1934 * Otherwise it is a normal OBJT_SWAP object and we can 1935 * fault the page in and remove the swap. 1936 */ 1937 m = vm_fault_object_page(object, IDX_TO_OFF(pindex), 1938 VM_PROT_NONE, 1939 VM_FAULT_DIRTY | VM_FAULT_UNSWAP, 1940 &error); 1941 if (m) 1942 vm_page_unhold(m); 1943 } 1944 } 1945 1946 int 1947 swap_pager_swapoff(int devidx) 1948 { 1949 vm_object_t object; 1950 struct swblock *swap; 1951 swblk_t v; 1952 int i; 1953 1954 lwkt_gettoken(&vm_token); 1955 lwkt_gettoken(&vmobj_token); 1956 rescan: 1957 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1958 if (object->type == OBJT_SWAP || object->type == OBJT_VNODE) { 1959 RB_FOREACH(swap, swblock_rb_tree, &object->swblock_root) { 1960 for (i = 0; i < SWAP_META_PAGES; ++i) { 1961 v = swap->swb_pages[i]; 1962 if (v != SWAPBLK_NONE && 1963 BLK2DEVIDX(v) == devidx) { 1964 swp_pager_fault_page( 1965 object, 1966 swap->swb_index + i); 1967 goto rescan; 1968 } 1969 } 1970 } 1971 } 1972 } 1973 lwkt_reltoken(&vmobj_token); 1974 lwkt_reltoken(&vm_token); 1975 1976 /* 1977 * If we fail to locate all swblocks we just fail gracefully and 1978 * do not bother to restore paging on the swap device. If the 1979 * user wants to retry the user can retry. 1980 */ 1981 if (swdevt[devidx].sw_nused) 1982 return (1); 1983 else 1984 return (0); 1985 } 1986 1987 /************************************************************************ 1988 * SWAP META DATA * 1989 ************************************************************************ 1990 * 1991 * These routines manipulate the swap metadata stored in the 1992 * OBJT_SWAP object. All swp_*() routines must be called at 1993 * splvm() because swap can be freed up by the low level vm_page 1994 * code which might be called from interrupts beyond what splbio() covers. 1995 * 1996 * Swap metadata is implemented with a global hash and not directly 1997 * linked into the object. Instead the object simply contains 1998 * appropriate tracking counters. 1999 */ 2000 2001 /* 2002 * Lookup the swblock containing the specified swap block index. 2003 * 2004 * The caller must hold vm_token. 2005 */ 2006 static __inline 2007 struct swblock * 2008 swp_pager_lookup(vm_object_t object, vm_pindex_t index) 2009 { 2010 index &= ~SWAP_META_MASK; 2011 return (RB_LOOKUP(swblock_rb_tree, &object->swblock_root, index)); 2012 } 2013 2014 /* 2015 * Remove a swblock from the RB tree. 2016 * 2017 * The caller must hold vm_token. 2018 */ 2019 static __inline 2020 void 2021 swp_pager_remove(vm_object_t object, struct swblock *swap) 2022 { 2023 RB_REMOVE(swblock_rb_tree, &object->swblock_root, swap); 2024 } 2025 2026 /* 2027 * Convert default object to swap object if necessary 2028 * 2029 * The caller must hold vm_token. 2030 */ 2031 static void 2032 swp_pager_meta_convert(vm_object_t object) 2033 { 2034 if (object->type == OBJT_DEFAULT) { 2035 object->type = OBJT_SWAP; 2036 KKASSERT(object->swblock_count == 0); 2037 } 2038 } 2039 2040 /* 2041 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 2042 * 2043 * We first convert the object to a swap object if it is a default 2044 * object. Vnode objects do not need to be converted. 2045 * 2046 * The specified swapblk is added to the object's swap metadata. If 2047 * the swapblk is not valid, it is freed instead. Any previously 2048 * assigned swapblk is freed. 2049 * 2050 * The caller must hold vm_token. 2051 */ 2052 static void 2053 swp_pager_meta_build(vm_object_t object, vm_pindex_t index, swblk_t swapblk) 2054 { 2055 struct swblock *swap; 2056 struct swblock *oswap; 2057 2058 KKASSERT(swapblk != SWAPBLK_NONE); 2059 2060 /* 2061 * Convert object if necessary 2062 */ 2063 if (object->type == OBJT_DEFAULT) 2064 swp_pager_meta_convert(object); 2065 2066 /* 2067 * Locate swblock. If not found create, but if we aren't adding 2068 * anything just return. If we run out of space in the map we wait 2069 * and, since the hash table may have changed, retry. 2070 */ 2071 retry: 2072 swap = swp_pager_lookup(object, index); 2073 2074 if (swap == NULL) { 2075 int i; 2076 2077 swap = zalloc(swap_zone); 2078 if (swap == NULL) { 2079 vm_wait(0); 2080 goto retry; 2081 } 2082 swap->swb_index = index & ~SWAP_META_MASK; 2083 swap->swb_count = 0; 2084 2085 ++object->swblock_count; 2086 2087 for (i = 0; i < SWAP_META_PAGES; ++i) 2088 swap->swb_pages[i] = SWAPBLK_NONE; 2089 oswap = RB_INSERT(swblock_rb_tree, &object->swblock_root, swap); 2090 KKASSERT(oswap == NULL); 2091 } 2092 2093 /* 2094 * Delete prior contents of metadata 2095 */ 2096 2097 index &= SWAP_META_MASK; 2098 2099 if (swap->swb_pages[index] != SWAPBLK_NONE) { 2100 swp_pager_freeswapspace(object, swap->swb_pages[index], 1); 2101 --swap->swb_count; 2102 } 2103 2104 /* 2105 * Enter block into metadata 2106 */ 2107 swap->swb_pages[index] = swapblk; 2108 if (swapblk != SWAPBLK_NONE) 2109 ++swap->swb_count; 2110 } 2111 2112 /* 2113 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2114 * 2115 * The requested range of blocks is freed, with any associated swap 2116 * returned to the swap bitmap. 2117 * 2118 * This routine will free swap metadata structures as they are cleaned 2119 * out. This routine does *NOT* operate on swap metadata associated 2120 * with resident pages. 2121 * 2122 * The caller must hold vm_token. 2123 */ 2124 static int swp_pager_meta_free_callback(struct swblock *swb, void *data); 2125 2126 static void 2127 swp_pager_meta_free(vm_object_t object, vm_pindex_t index, vm_pindex_t count) 2128 { 2129 struct swfreeinfo info; 2130 2131 /* 2132 * Nothing to do 2133 */ 2134 if (object->swblock_count == 0) { 2135 KKASSERT(RB_EMPTY(&object->swblock_root)); 2136 return; 2137 } 2138 if (count == 0) 2139 return; 2140 2141 /* 2142 * Setup for RB tree scan. Note that the pindex range can be huge 2143 * due to the 64 bit page index space so we cannot safely iterate. 2144 */ 2145 info.object = object; 2146 info.basei = index & ~SWAP_META_MASK; 2147 info.begi = index; 2148 info.endi = index + count - 1; 2149 swblock_rb_tree_RB_SCAN(&object->swblock_root, rb_swblock_scancmp, 2150 swp_pager_meta_free_callback, &info); 2151 } 2152 2153 /* 2154 * The caller must hold vm_token. 2155 */ 2156 static 2157 int 2158 swp_pager_meta_free_callback(struct swblock *swap, void *data) 2159 { 2160 struct swfreeinfo *info = data; 2161 vm_object_t object = info->object; 2162 int index; 2163 int eindex; 2164 2165 /* 2166 * Figure out the range within the swblock. The wider scan may 2167 * return edge-case swap blocks when the start and/or end points 2168 * are in the middle of a block. 2169 */ 2170 if (swap->swb_index < info->begi) 2171 index = (int)info->begi & SWAP_META_MASK; 2172 else 2173 index = 0; 2174 2175 if (swap->swb_index + SWAP_META_PAGES > info->endi) 2176 eindex = (int)info->endi & SWAP_META_MASK; 2177 else 2178 eindex = SWAP_META_MASK; 2179 2180 /* 2181 * Scan and free the blocks. The loop terminates early 2182 * if (swap) runs out of blocks and could be freed. 2183 */ 2184 while (index <= eindex) { 2185 swblk_t v = swap->swb_pages[index]; 2186 2187 if (v != SWAPBLK_NONE) { 2188 swp_pager_freeswapspace(object, v, 1); 2189 swap->swb_pages[index] = SWAPBLK_NONE; 2190 if (--swap->swb_count == 0) { 2191 swp_pager_remove(object, swap); 2192 zfree(swap_zone, swap); 2193 --object->swblock_count; 2194 break; 2195 } 2196 } 2197 ++index; 2198 } 2199 /* swap may be invalid here due to zfree above */ 2200 return(0); 2201 } 2202 2203 /* 2204 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2205 * 2206 * This routine locates and destroys all swap metadata associated with 2207 * an object. 2208 * 2209 * The caller must hold vm_token. 2210 */ 2211 static void 2212 swp_pager_meta_free_all(vm_object_t object) 2213 { 2214 struct swblock *swap; 2215 int i; 2216 2217 while ((swap = RB_ROOT(&object->swblock_root)) != NULL) { 2218 swp_pager_remove(object, swap); 2219 for (i = 0; i < SWAP_META_PAGES; ++i) { 2220 swblk_t v = swap->swb_pages[i]; 2221 if (v != SWAPBLK_NONE) { 2222 --swap->swb_count; 2223 swp_pager_freeswapspace(object, v, 1); 2224 } 2225 } 2226 if (swap->swb_count != 0) 2227 panic("swap_pager_meta_free_all: swb_count != 0"); 2228 zfree(swap_zone, swap); 2229 --object->swblock_count; 2230 } 2231 KKASSERT(object->swblock_count == 0); 2232 } 2233 2234 /* 2235 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. 2236 * 2237 * This routine is capable of looking up, popping, or freeing 2238 * swapblk assignments in the swap meta data or in the vm_page_t. 2239 * The routine typically returns the swapblk being looked-up, or popped, 2240 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block 2241 * was invalid. This routine will automatically free any invalid 2242 * meta-data swapblks. 2243 * 2244 * It is not possible to store invalid swapblks in the swap meta data 2245 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking. 2246 * 2247 * When acting on a busy resident page and paging is in progress, we 2248 * have to wait until paging is complete but otherwise can act on the 2249 * busy page. 2250 * 2251 * SWM_FREE remove and free swap block from metadata 2252 * SWM_POP remove from meta data but do not free.. pop it out 2253 * 2254 * The caller must hold vm_token. 2255 */ 2256 static swblk_t 2257 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t index, int flags) 2258 { 2259 struct swblock *swap; 2260 swblk_t r1; 2261 2262 if (object->swblock_count == 0) 2263 return(SWAPBLK_NONE); 2264 2265 r1 = SWAPBLK_NONE; 2266 swap = swp_pager_lookup(object, index); 2267 2268 if (swap != NULL) { 2269 index &= SWAP_META_MASK; 2270 r1 = swap->swb_pages[index]; 2271 2272 if (r1 != SWAPBLK_NONE) { 2273 if (flags & SWM_FREE) { 2274 swp_pager_freeswapspace(object, r1, 1); 2275 r1 = SWAPBLK_NONE; 2276 } 2277 if (flags & (SWM_FREE|SWM_POP)) { 2278 swap->swb_pages[index] = SWAPBLK_NONE; 2279 if (--swap->swb_count == 0) { 2280 swp_pager_remove(object, swap); 2281 zfree(swap_zone, swap); 2282 --object->swblock_count; 2283 } 2284 } 2285 } 2286 } 2287 return(r1); 2288 } 2289