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 swp_pager_meta_free_all(object); 459 lwkt_reltoken(&vm_token); 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 vm_token. 477 * This routine may not block. 478 * 479 * NOTE: vm_token must be held to avoid races with bitmap frees from 480 * vm_page_remove() via swap_pager_page_removed(). 481 */ 482 static __inline swblk_t 483 swp_pager_getswapspace(vm_object_t object, int npages) 484 { 485 swblk_t blk; 486 487 ASSERT_LWKT_TOKEN_HELD(&vm_token); 488 489 if ((blk = blist_alloc(swapblist, npages)) == SWAPBLK_NONE) { 490 if (swap_pager_full != 2) { 491 kprintf("swap_pager_getswapspace: failed\n"); 492 swap_pager_full = 2; 493 swap_pager_almost_full = 1; 494 } 495 } else { 496 swapacctspace(blk, -npages); 497 if (object->type == OBJT_SWAP) 498 vm_swap_anon_use += npages; 499 else 500 vm_swap_cache_use += npages; 501 swp_sizecheck(); 502 } 503 return(blk); 504 } 505 506 /* 507 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 508 * 509 * This routine returns the specified swap blocks back to the bitmap. 510 * 511 * Note: This routine may not block (it could in the old swap code), 512 * and through the use of the new blist routines it does not block. 513 * 514 * We must be called at splvm() to avoid races with bitmap frees from 515 * vm_page_remove() aka swap_pager_page_removed(). 516 * 517 * The caller must hold vm_token. 518 * This routine may not block. 519 */ 520 521 static __inline void 522 swp_pager_freeswapspace(vm_object_t object, swblk_t blk, int npages) 523 { 524 struct swdevt *sp = &swdevt[BLK2DEVIDX(blk)]; 525 526 sp->sw_nused -= npages; 527 if (object->type == OBJT_SWAP) 528 vm_swap_anon_use -= npages; 529 else 530 vm_swap_cache_use -= npages; 531 532 if (sp->sw_flags & SW_CLOSING) 533 return; 534 535 blist_free(swapblist, blk, npages); 536 vm_swap_size += npages; 537 swp_sizecheck(); 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 lwkt_gettoken(&vm_token); 558 swp_pager_meta_free(object, start, size); 559 lwkt_reltoken(&vm_token); 560 } 561 562 /* 563 * No requirements. 564 */ 565 void 566 swap_pager_freespace_all(vm_object_t object) 567 { 568 lwkt_gettoken(&vm_token); 569 swp_pager_meta_free_all(object); 570 lwkt_reltoken(&vm_token); 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 vm_token. 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_token); 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 vm_token. 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 return(0); 644 } 645 646 /* 647 * Called by vm_page_alloc() when a new VM page is inserted 648 * into a VM object. Checks whether swap has been assigned to 649 * the page and sets PG_SWAPPED as necessary. 650 * 651 * No requirements. 652 */ 653 void 654 swap_pager_page_inserted(vm_page_t m) 655 { 656 if (m->object->swblock_count) { 657 lwkt_gettoken(&vm_token); 658 if (swp_pager_meta_ctl(m->object, m->pindex, 0) != SWAPBLK_NONE) 659 vm_page_flag_set(m, PG_SWAPPED); 660 lwkt_reltoken(&vm_token); 661 } 662 } 663 664 /* 665 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 666 * 667 * Assigns swap blocks to the specified range within the object. The 668 * swap blocks are not zerod. Any previous swap assignment is destroyed. 669 * 670 * Returns 0 on success, -1 on failure. 671 * 672 * The caller is responsible for avoiding races in the specified range. 673 * No other requirements. 674 */ 675 int 676 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 677 { 678 int n = 0; 679 swblk_t blk = SWAPBLK_NONE; 680 vm_pindex_t beg = start; /* save start index */ 681 682 lwkt_gettoken(&vm_token); 683 while (size) { 684 if (n == 0) { 685 n = BLIST_MAX_ALLOC; 686 while ((blk = swp_pager_getswapspace(object, n)) == 687 SWAPBLK_NONE) 688 { 689 n >>= 1; 690 if (n == 0) { 691 swp_pager_meta_free(object, beg, 692 start - beg); 693 lwkt_reltoken(&vm_token); 694 return(-1); 695 } 696 } 697 } 698 swp_pager_meta_build(object, start, blk); 699 --size; 700 ++start; 701 ++blk; 702 --n; 703 } 704 swp_pager_meta_free(object, start, n); 705 lwkt_reltoken(&vm_token); 706 return(0); 707 } 708 709 /* 710 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 711 * and destroy the source. 712 * 713 * Copy any valid swapblks from the source to the destination. In 714 * cases where both the source and destination have a valid swapblk, 715 * we keep the destination's. 716 * 717 * This routine is allowed to block. It may block allocating metadata 718 * indirectly through swp_pager_meta_build() or if paging is still in 719 * progress on the source. 720 * 721 * This routine can be called at any spl 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 * 730 * The source object is of type OBJT_SWAP. 731 * 732 * The source and destination objects must be locked or 733 * inaccessible (XXX are they ?) 734 * 735 * The caller must hold vm_token. 736 */ 737 void 738 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 739 vm_pindex_t base_index, int destroysource) 740 { 741 vm_pindex_t i; 742 743 ASSERT_LWKT_TOKEN_HELD(&vm_token); 744 745 /* 746 * transfer source to destination. 747 */ 748 for (i = 0; i < dstobject->size; ++i) { 749 swblk_t dstaddr; 750 751 /* 752 * Locate (without changing) the swapblk on the destination, 753 * unless it is invalid in which case free it silently, or 754 * if the destination is a resident page, in which case the 755 * source is thrown away. 756 */ 757 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 758 759 if (dstaddr == SWAPBLK_NONE) { 760 /* 761 * Destination has no swapblk and is not resident, 762 * copy source. 763 */ 764 swblk_t srcaddr; 765 766 srcaddr = swp_pager_meta_ctl(srcobject, 767 base_index + i, SWM_POP); 768 769 if (srcaddr != SWAPBLK_NONE) 770 swp_pager_meta_build(dstobject, i, srcaddr); 771 } else { 772 /* 773 * Destination has valid swapblk or it is represented 774 * by a resident page. We destroy the sourceblock. 775 */ 776 swp_pager_meta_ctl(srcobject, base_index + i, SWM_FREE); 777 } 778 } 779 780 /* 781 * Free left over swap blocks in source. 782 * 783 * We have to revert the type to OBJT_DEFAULT so we do not accidently 784 * double-remove the object from the swap queues. 785 */ 786 if (destroysource) { 787 /* 788 * Reverting the type is not necessary, the caller is going 789 * to destroy srcobject directly, but I'm doing it here 790 * for consistency since we've removed the object from its 791 * queues. 792 */ 793 swp_pager_meta_free_all(srcobject); 794 if (srcobject->type == OBJT_SWAP) 795 srcobject->type = OBJT_DEFAULT; 796 } 797 } 798 799 /* 800 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 801 * the requested page. 802 * 803 * We determine whether good backing store exists for the requested 804 * page and return TRUE if it does, FALSE if it doesn't. 805 * 806 * If TRUE, we also try to determine how much valid, contiguous backing 807 * store exists before and after the requested page within a reasonable 808 * distance. We do not try to restrict it to the swap device stripe 809 * (that is handled in getpages/putpages). It probably isn't worth 810 * doing here. 811 * 812 * No requirements. 813 */ 814 boolean_t 815 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex) 816 { 817 swblk_t blk0; 818 819 /* 820 * do we have good backing store at the requested index ? 821 */ 822 823 lwkt_gettoken(&vm_token); 824 blk0 = swp_pager_meta_ctl(object, pindex, 0); 825 826 if (blk0 == SWAPBLK_NONE) { 827 lwkt_reltoken(&vm_token); 828 return (FALSE); 829 } 830 lwkt_reltoken(&vm_token); 831 return (TRUE); 832 } 833 834 /* 835 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 836 * 837 * This removes any associated swap backing store, whether valid or 838 * not, from the page. This operates on any VM object, not just OBJT_SWAP 839 * objects. 840 * 841 * This routine is typically called when a page is made dirty, at 842 * which point any associated swap can be freed. MADV_FREE also 843 * calls us in a special-case situation 844 * 845 * NOTE!!! If the page is clean and the swap was valid, the caller 846 * should make the page dirty before calling this routine. This routine 847 * does NOT change the m->dirty status of the page. Also: MADV_FREE 848 * depends on it. 849 * 850 * The page must be busied or soft-busied. 851 * The caller must hold vm_token if the caller does not wish to block here. 852 * No other requirements. 853 */ 854 void 855 swap_pager_unswapped(vm_page_t m) 856 { 857 if (m->flags & PG_SWAPPED) { 858 lwkt_gettoken(&vm_token); 859 KKASSERT(m->flags & PG_SWAPPED); 860 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); 861 vm_page_flag_clear(m, PG_SWAPPED); 862 lwkt_reltoken(&vm_token); 863 } 864 } 865 866 /* 867 * SWAP_PAGER_STRATEGY() - read, write, free blocks 868 * 869 * This implements a VM OBJECT strategy function using swap backing store. 870 * This can operate on any VM OBJECT type, not necessarily just OBJT_SWAP 871 * types. 872 * 873 * This is intended to be a cacheless interface (i.e. caching occurs at 874 * higher levels), and is also used as a swap-based SSD cache for vnode 875 * and device objects. 876 * 877 * All I/O goes directly to and from the swap device. 878 * 879 * We currently attempt to run I/O synchronously or asynchronously as 880 * the caller requests. This isn't perfect because we loose error 881 * sequencing when we run multiple ops in parallel to satisfy a request. 882 * But this is swap, so we let it all hang out. 883 * 884 * No requirements. 885 */ 886 void 887 swap_pager_strategy(vm_object_t object, struct bio *bio) 888 { 889 struct buf *bp = bio->bio_buf; 890 struct bio *nbio; 891 vm_pindex_t start; 892 vm_pindex_t biox_blkno = 0; 893 int count; 894 char *data; 895 struct bio *biox; 896 struct buf *bufx; 897 struct bio_track *track; 898 899 /* 900 * tracking for swapdev vnode I/Os 901 */ 902 if (bp->b_cmd == BUF_CMD_READ) 903 track = &swapdev_vp->v_track_read; 904 else 905 track = &swapdev_vp->v_track_write; 906 907 if (bp->b_bcount & PAGE_MASK) { 908 bp->b_error = EINVAL; 909 bp->b_flags |= B_ERROR | B_INVAL; 910 biodone(bio); 911 kprintf("swap_pager_strategy: bp %p offset %lld size %d, " 912 "not page bounded\n", 913 bp, (long long)bio->bio_offset, (int)bp->b_bcount); 914 return; 915 } 916 917 /* 918 * Clear error indication, initialize page index, count, data pointer. 919 */ 920 bp->b_error = 0; 921 bp->b_flags &= ~B_ERROR; 922 bp->b_resid = bp->b_bcount; 923 924 start = (vm_pindex_t)(bio->bio_offset >> PAGE_SHIFT); 925 count = howmany(bp->b_bcount, PAGE_SIZE); 926 data = bp->b_data; 927 928 /* 929 * Deal with BUF_CMD_FREEBLKS 930 */ 931 if (bp->b_cmd == BUF_CMD_FREEBLKS) { 932 /* 933 * FREE PAGE(s) - destroy underlying swap that is no longer 934 * needed. 935 */ 936 lwkt_gettoken(&vm_token); 937 swp_pager_meta_free(object, start, count); 938 lwkt_reltoken(&vm_token); 939 bp->b_resid = 0; 940 biodone(bio); 941 return; 942 } 943 944 /* 945 * We need to be able to create a new cluster of I/O's. We cannot 946 * use the caller fields of the passed bio so push a new one. 947 * 948 * Because nbio is just a placeholder for the cluster links, 949 * we can biodone() the original bio instead of nbio to make 950 * things a bit more efficient. 951 */ 952 nbio = push_bio(bio); 953 nbio->bio_offset = bio->bio_offset; 954 nbio->bio_caller_info1.cluster_head = NULL; 955 nbio->bio_caller_info2.cluster_tail = NULL; 956 957 biox = NULL; 958 bufx = NULL; 959 960 /* 961 * Execute read or write 962 */ 963 lwkt_gettoken(&vm_token); 964 while (count > 0) { 965 swblk_t blk; 966 967 /* 968 * Obtain block. If block not found and writing, allocate a 969 * new block and build it into the object. 970 */ 971 blk = swp_pager_meta_ctl(object, start, 0); 972 if ((blk == SWAPBLK_NONE) && bp->b_cmd != BUF_CMD_READ) { 973 blk = swp_pager_getswapspace(object, 1); 974 if (blk == SWAPBLK_NONE) { 975 bp->b_error = ENOMEM; 976 bp->b_flags |= B_ERROR; 977 break; 978 } 979 swp_pager_meta_build(object, start, blk); 980 } 981 982 /* 983 * Do we have to flush our current collection? Yes if: 984 * 985 * - no swap block at this index 986 * - swap block is not contiguous 987 * - we cross a physical disk boundry in the 988 * stripe. 989 */ 990 if ( 991 biox && (biox_blkno + btoc(bufx->b_bcount) != blk || 992 ((biox_blkno ^ blk) & dmmax_mask) 993 ) 994 ) { 995 if (bp->b_cmd == BUF_CMD_READ) { 996 ++mycpu->gd_cnt.v_swapin; 997 mycpu->gd_cnt.v_swappgsin += btoc(bufx->b_bcount); 998 } else { 999 ++mycpu->gd_cnt.v_swapout; 1000 mycpu->gd_cnt.v_swappgsout += btoc(bufx->b_bcount); 1001 bufx->b_dirtyend = bufx->b_bcount; 1002 } 1003 1004 /* 1005 * Finished with this buf. 1006 */ 1007 KKASSERT(bufx->b_bcount != 0); 1008 if (bufx->b_cmd != BUF_CMD_READ) 1009 bufx->b_dirtyend = bufx->b_bcount; 1010 biox = NULL; 1011 bufx = NULL; 1012 } 1013 1014 /* 1015 * Add new swapblk to biox, instantiating biox if necessary. 1016 * Zero-fill reads are able to take a shortcut. 1017 */ 1018 if (blk == SWAPBLK_NONE) { 1019 /* 1020 * We can only get here if we are reading. Since 1021 * we are at splvm() we can safely modify b_resid, 1022 * even if chain ops are in progress. 1023 */ 1024 bzero(data, PAGE_SIZE); 1025 bp->b_resid -= PAGE_SIZE; 1026 } else { 1027 if (biox == NULL) { 1028 /* XXX chain count > 4, wait to <= 4 */ 1029 1030 bufx = getpbuf(NULL); 1031 biox = &bufx->b_bio1; 1032 cluster_append(nbio, bufx); 1033 bufx->b_flags |= (bufx->b_flags & B_ORDERED); 1034 bufx->b_cmd = bp->b_cmd; 1035 biox->bio_done = swap_chain_iodone; 1036 biox->bio_offset = (off_t)blk << PAGE_SHIFT; 1037 biox->bio_caller_info1.cluster_parent = nbio; 1038 biox_blkno = blk; 1039 bufx->b_bcount = 0; 1040 bufx->b_data = data; 1041 } 1042 bufx->b_bcount += PAGE_SIZE; 1043 } 1044 --count; 1045 ++start; 1046 data += PAGE_SIZE; 1047 } 1048 lwkt_reltoken(&vm_token); 1049 1050 /* 1051 * Flush out last buffer 1052 */ 1053 if (biox) { 1054 if (bufx->b_cmd == BUF_CMD_READ) { 1055 ++mycpu->gd_cnt.v_swapin; 1056 mycpu->gd_cnt.v_swappgsin += btoc(bufx->b_bcount); 1057 } else { 1058 ++mycpu->gd_cnt.v_swapout; 1059 mycpu->gd_cnt.v_swappgsout += btoc(bufx->b_bcount); 1060 bufx->b_dirtyend = bufx->b_bcount; 1061 } 1062 KKASSERT(bufx->b_bcount); 1063 if (bufx->b_cmd != BUF_CMD_READ) 1064 bufx->b_dirtyend = bufx->b_bcount; 1065 /* biox, bufx = NULL */ 1066 } 1067 1068 /* 1069 * Now initiate all the I/O. Be careful looping on our chain as 1070 * I/O's may complete while we are still initiating them. 1071 * 1072 * If the request is a 100% sparse read no bios will be present 1073 * and we just biodone() the buffer. 1074 */ 1075 nbio->bio_caller_info2.cluster_tail = NULL; 1076 bufx = nbio->bio_caller_info1.cluster_head; 1077 1078 if (bufx) { 1079 while (bufx) { 1080 biox = &bufx->b_bio1; 1081 BUF_KERNPROC(bufx); 1082 bufx = bufx->b_cluster_next; 1083 vn_strategy(swapdev_vp, biox); 1084 } 1085 } else { 1086 biodone(bio); 1087 } 1088 1089 /* 1090 * Completion of the cluster will also call biodone_chain(nbio). 1091 * We never call biodone(nbio) so we don't have to worry about 1092 * setting up a bio_done callback. It's handled in the sub-IO. 1093 */ 1094 /**/ 1095 } 1096 1097 /* 1098 * biodone callback 1099 * 1100 * No requirements. 1101 */ 1102 static void 1103 swap_chain_iodone(struct bio *biox) 1104 { 1105 struct buf **nextp; 1106 struct buf *bufx; /* chained sub-buffer */ 1107 struct bio *nbio; /* parent nbio with chain glue */ 1108 struct buf *bp; /* original bp associated with nbio */ 1109 int chain_empty; 1110 1111 bufx = biox->bio_buf; 1112 nbio = biox->bio_caller_info1.cluster_parent; 1113 bp = nbio->bio_buf; 1114 1115 /* 1116 * Update the original buffer 1117 */ 1118 KKASSERT(bp != NULL); 1119 if (bufx->b_flags & B_ERROR) { 1120 atomic_set_int(&bufx->b_flags, B_ERROR); 1121 bp->b_error = bufx->b_error; /* race ok */ 1122 } else if (bufx->b_resid != 0) { 1123 atomic_set_int(&bufx->b_flags, B_ERROR); 1124 bp->b_error = EINVAL; /* race ok */ 1125 } else { 1126 atomic_subtract_int(&bp->b_resid, bufx->b_bcount); 1127 } 1128 1129 /* 1130 * Remove us from the chain. 1131 */ 1132 spin_lock(&bp->b_lock.lk_spinlock); 1133 nextp = &nbio->bio_caller_info1.cluster_head; 1134 while (*nextp != bufx) { 1135 KKASSERT(*nextp != NULL); 1136 nextp = &(*nextp)->b_cluster_next; 1137 } 1138 *nextp = bufx->b_cluster_next; 1139 chain_empty = (nbio->bio_caller_info1.cluster_head == NULL); 1140 spin_unlock(&bp->b_lock.lk_spinlock); 1141 1142 /* 1143 * Clean up bufx. If the chain is now empty we finish out 1144 * the parent. Note that we may be racing other completions 1145 * so we must use the chain_empty status from above. 1146 */ 1147 if (chain_empty) { 1148 if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) { 1149 atomic_set_int(&bp->b_flags, B_ERROR); 1150 bp->b_error = EINVAL; 1151 } 1152 biodone_chain(nbio); 1153 } 1154 relpbuf(bufx, NULL); 1155 } 1156 1157 /* 1158 * SWAP_PAGER_GETPAGES() - bring page in from swap 1159 * 1160 * The requested page may have to be brought in from swap. Calculate the 1161 * swap block and bring in additional pages if possible. All pages must 1162 * have contiguous swap block assignments and reside in the same object. 1163 * 1164 * The caller has a single vm_object_pip_add() reference prior to 1165 * calling us and we should return with the same. 1166 * 1167 * The caller has BUSY'd the page. We should return with (*mpp) left busy, 1168 * and any additinal pages unbusied. 1169 * 1170 * If the caller encounters a PG_RAM page it will pass it to us even though 1171 * it may be valid and dirty. We cannot overwrite the page in this case! 1172 * The case is used to allow us to issue pure read-aheads. 1173 * 1174 * NOTE! XXX This code does not entirely pipeline yet due to the fact that 1175 * the PG_RAM page is validated at the same time as mreq. What we 1176 * really need to do is issue a separate read-ahead pbuf. 1177 * 1178 * No requirements. 1179 */ 1180 static int 1181 swap_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess) 1182 { 1183 struct buf *bp; 1184 struct bio *bio; 1185 vm_page_t mreq; 1186 vm_page_t m; 1187 vm_offset_t kva; 1188 swblk_t blk; 1189 int i; 1190 int j; 1191 int raonly; 1192 vm_page_t marray[XIO_INTERNAL_PAGES]; 1193 1194 mreq = *mpp; 1195 1196 if (mreq->object != object) { 1197 panic("swap_pager_getpages: object mismatch %p/%p", 1198 object, 1199 mreq->object 1200 ); 1201 } 1202 1203 /* 1204 * We don't want to overwrite a fully valid page as it might be 1205 * dirty. This case can occur when e.g. vm_fault hits a perfectly 1206 * valid page with PG_RAM set. 1207 * 1208 * In this case we see if the next page is a suitable page-in 1209 * candidate and if it is we issue read-ahead. PG_RAM will be 1210 * set on the last page of the read-ahead to continue the pipeline. 1211 */ 1212 if (mreq->valid == VM_PAGE_BITS_ALL) { 1213 if (swap_burst_read == 0 || mreq->pindex + 1 >= object->size) 1214 return(VM_PAGER_OK); 1215 lwkt_gettoken(&vm_token); 1216 blk = swp_pager_meta_ctl(object, mreq->pindex + 1, 0); 1217 if (blk == SWAPBLK_NONE) { 1218 lwkt_reltoken(&vm_token); 1219 return(VM_PAGER_OK); 1220 } 1221 m = vm_page_lookup(object, mreq->pindex + 1); 1222 if (m == NULL) { 1223 m = vm_page_alloc(object, mreq->pindex + 1, 1224 VM_ALLOC_QUICK); 1225 if (m == NULL) { 1226 lwkt_reltoken(&vm_token); 1227 return(VM_PAGER_OK); 1228 } 1229 } else { 1230 if ((m->flags & PG_BUSY) || m->busy || m->valid) { 1231 lwkt_reltoken(&vm_token); 1232 return(VM_PAGER_OK); 1233 } 1234 vm_page_unqueue_nowakeup(m); 1235 vm_page_busy(m); 1236 } 1237 mreq = m; 1238 raonly = 1; 1239 lwkt_reltoken(&vm_token); 1240 } else { 1241 raonly = 0; 1242 } 1243 1244 /* 1245 * Try to block-read contiguous pages from swap if sequential, 1246 * otherwise just read one page. Contiguous pages from swap must 1247 * reside within a single device stripe because the I/O cannot be 1248 * broken up across multiple stripes. 1249 * 1250 * Note that blk and iblk can be SWAPBLK_NONE but the loop is 1251 * set up such that the case(s) are handled implicitly. 1252 */ 1253 lwkt_gettoken(&vm_token); 1254 blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0); 1255 marray[0] = mreq; 1256 1257 for (i = 1; swap_burst_read && 1258 i < XIO_INTERNAL_PAGES && 1259 mreq->pindex + i < object->size; ++i) { 1260 swblk_t iblk; 1261 1262 iblk = swp_pager_meta_ctl(object, mreq->pindex + i, 0); 1263 if (iblk != blk + i) 1264 break; 1265 if ((blk ^ iblk) & dmmax_mask) 1266 break; 1267 m = vm_page_lookup(object, mreq->pindex + i); 1268 if (m == NULL) { 1269 m = vm_page_alloc(object, mreq->pindex + i, 1270 VM_ALLOC_QUICK); 1271 if (m == NULL) 1272 break; 1273 } else { 1274 if ((m->flags & PG_BUSY) || m->busy || m->valid) 1275 break; 1276 vm_page_unqueue_nowakeup(m); 1277 vm_page_busy(m); 1278 } 1279 marray[i] = m; 1280 } 1281 if (i > 1) 1282 vm_page_flag_set(marray[i - 1], PG_RAM); 1283 1284 lwkt_reltoken(&vm_token); 1285 1286 /* 1287 * If mreq is the requested page and we have nothing to do return 1288 * VM_PAGER_FAIL. If raonly is set mreq is just another read-ahead 1289 * page and must be cleaned up. 1290 */ 1291 if (blk == SWAPBLK_NONE) { 1292 KKASSERT(i == 1); 1293 if (raonly) { 1294 vnode_pager_freepage(mreq); 1295 return(VM_PAGER_OK); 1296 } else { 1297 return(VM_PAGER_FAIL); 1298 } 1299 } 1300 1301 /* 1302 * map our page(s) into kva for input 1303 */ 1304 bp = getpbuf_kva(&nsw_rcount); 1305 bio = &bp->b_bio1; 1306 kva = (vm_offset_t) bp->b_kvabase; 1307 bcopy(marray, bp->b_xio.xio_pages, i * sizeof(vm_page_t)); 1308 pmap_qenter(kva, bp->b_xio.xio_pages, i); 1309 1310 bp->b_data = (caddr_t)kva; 1311 bp->b_bcount = PAGE_SIZE * i; 1312 bp->b_xio.xio_npages = i; 1313 bio->bio_done = swp_pager_async_iodone; 1314 bio->bio_offset = (off_t)blk << PAGE_SHIFT; 1315 bio->bio_caller_info1.index = SWBIO_READ; 1316 1317 /* 1318 * Set index. If raonly set the index beyond the array so all 1319 * the pages are treated the same, otherwise the original mreq is 1320 * at index 0. 1321 */ 1322 if (raonly) 1323 bio->bio_driver_info = (void *)(intptr_t)i; 1324 else 1325 bio->bio_driver_info = (void *)(intptr_t)0; 1326 1327 for (j = 0; j < i; ++j) 1328 vm_page_flag_set(bp->b_xio.xio_pages[j], PG_SWAPINPROG); 1329 1330 mycpu->gd_cnt.v_swapin++; 1331 mycpu->gd_cnt.v_swappgsin += bp->b_xio.xio_npages; 1332 1333 /* 1334 * We still hold the lock on mreq, and our automatic completion routine 1335 * does not remove it. 1336 */ 1337 vm_object_pip_add(object, bp->b_xio.xio_npages); 1338 1339 /* 1340 * perform the I/O. NOTE!!! bp cannot be considered valid after 1341 * this point because we automatically release it on completion. 1342 * Instead, we look at the one page we are interested in which we 1343 * still hold a lock on even through the I/O completion. 1344 * 1345 * The other pages in our m[] array are also released on completion, 1346 * so we cannot assume they are valid anymore either. 1347 */ 1348 bp->b_cmd = BUF_CMD_READ; 1349 BUF_KERNPROC(bp); 1350 vn_strategy(swapdev_vp, bio); 1351 1352 /* 1353 * Wait for the page we want to complete. PG_SWAPINPROG is always 1354 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1355 * is set in the meta-data. 1356 * 1357 * If this is a read-ahead only we return immediately without 1358 * waiting for I/O. 1359 */ 1360 if (raonly) 1361 return(VM_PAGER_OK); 1362 1363 /* 1364 * Read-ahead includes originally requested page case. 1365 */ 1366 lwkt_gettoken(&vm_token); 1367 while ((mreq->flags & PG_SWAPINPROG) != 0) { 1368 vm_page_flag_set(mreq, PG_WANTED | PG_REFERENCED); 1369 mycpu->gd_cnt.v_intrans++; 1370 if (tsleep(mreq, 0, "swread", hz*20)) { 1371 kprintf( 1372 "swap_pager: indefinite wait buffer: " 1373 " offset: %lld, size: %ld\n", 1374 (long long)bio->bio_offset, 1375 (long)bp->b_bcount 1376 ); 1377 } 1378 } 1379 lwkt_reltoken(&vm_token); 1380 1381 /* 1382 * mreq is left bussied after completion, but all the other pages 1383 * are freed. If we had an unrecoverable read error the page will 1384 * not be valid. 1385 */ 1386 if (mreq->valid != VM_PAGE_BITS_ALL) 1387 return(VM_PAGER_ERROR); 1388 else 1389 return(VM_PAGER_OK); 1390 1391 /* 1392 * A final note: in a low swap situation, we cannot deallocate swap 1393 * and mark a page dirty here because the caller is likely to mark 1394 * the page clean when we return, causing the page to possibly revert 1395 * to all-zero's later. 1396 */ 1397 } 1398 1399 /* 1400 * swap_pager_putpages: 1401 * 1402 * Assign swap (if necessary) and initiate I/O on the specified pages. 1403 * 1404 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1405 * are automatically converted to SWAP objects. 1406 * 1407 * In a low memory situation we may block in vn_strategy(), but the new 1408 * vm_page reservation system coupled with properly written VFS devices 1409 * should ensure that no low-memory deadlock occurs. This is an area 1410 * which needs work. 1411 * 1412 * The parent has N vm_object_pip_add() references prior to 1413 * calling us and will remove references for rtvals[] that are 1414 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1415 * completion. 1416 * 1417 * The parent has soft-busy'd the pages it passes us and will unbusy 1418 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1419 * We need to unbusy the rest on I/O completion. 1420 * 1421 * No requirements. 1422 */ 1423 void 1424 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1425 boolean_t sync, int *rtvals) 1426 { 1427 int i; 1428 int n = 0; 1429 1430 if (count && m[0]->object != object) { 1431 panic("swap_pager_getpages: object mismatch %p/%p", 1432 object, 1433 m[0]->object 1434 ); 1435 } 1436 1437 /* 1438 * Step 1 1439 * 1440 * Turn object into OBJT_SWAP 1441 * check for bogus sysops 1442 * force sync if not pageout process 1443 */ 1444 if (object->type == OBJT_DEFAULT) { 1445 lwkt_gettoken(&vm_token); 1446 if (object->type == OBJT_DEFAULT) 1447 swp_pager_meta_convert(object); 1448 lwkt_reltoken(&vm_token); 1449 } 1450 1451 if (curthread != pagethread) 1452 sync = TRUE; 1453 1454 /* 1455 * Step 2 1456 * 1457 * Update nsw parameters from swap_async_max sysctl values. 1458 * Do not let the sysop crash the machine with bogus numbers. 1459 */ 1460 1461 if (swap_async_max != nsw_wcount_async_max) { 1462 int n; 1463 1464 /* 1465 * limit range 1466 */ 1467 if ((n = swap_async_max) > nswbuf / 2) 1468 n = nswbuf / 2; 1469 if (n < 1) 1470 n = 1; 1471 swap_async_max = n; 1472 1473 /* 1474 * Adjust difference ( if possible ). If the current async 1475 * count is too low, we may not be able to make the adjustment 1476 * at this time. 1477 */ 1478 lwkt_gettoken(&vm_token); 1479 n -= nsw_wcount_async_max; 1480 if (nsw_wcount_async + n >= 0) { 1481 nsw_wcount_async += n; 1482 nsw_wcount_async_max += n; 1483 wakeup(&nsw_wcount_async); 1484 } 1485 lwkt_reltoken(&vm_token); 1486 } 1487 1488 /* 1489 * Step 3 1490 * 1491 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1492 * The page is left dirty until the pageout operation completes 1493 * successfully. 1494 */ 1495 1496 for (i = 0; i < count; i += n) { 1497 struct buf *bp; 1498 struct bio *bio; 1499 swblk_t blk; 1500 int j; 1501 1502 /* 1503 * Maximum I/O size is limited by a number of factors. 1504 */ 1505 1506 n = min(BLIST_MAX_ALLOC, count - i); 1507 n = min(n, nsw_cluster_max); 1508 1509 lwkt_gettoken(&vm_token); 1510 1511 /* 1512 * Get biggest block of swap we can. If we fail, fall 1513 * back and try to allocate a smaller block. Don't go 1514 * overboard trying to allocate space if it would overly 1515 * fragment swap. 1516 */ 1517 while ( 1518 (blk = swp_pager_getswapspace(object, n)) == SWAPBLK_NONE && 1519 n > 4 1520 ) { 1521 n >>= 1; 1522 } 1523 if (blk == SWAPBLK_NONE) { 1524 for (j = 0; j < n; ++j) 1525 rtvals[i+j] = VM_PAGER_FAIL; 1526 lwkt_reltoken(&vm_token); 1527 continue; 1528 } 1529 1530 /* 1531 * The I/O we are constructing cannot cross a physical 1532 * disk boundry in the swap stripe. Note: we are still 1533 * at splvm(). 1534 */ 1535 if ((blk ^ (blk + n)) & dmmax_mask) { 1536 j = ((blk + dmmax) & dmmax_mask) - blk; 1537 swp_pager_freeswapspace(object, blk + j, n - j); 1538 n = j; 1539 } 1540 1541 /* 1542 * All I/O parameters have been satisfied, build the I/O 1543 * request and assign the swap space. 1544 */ 1545 if (sync == TRUE) 1546 bp = getpbuf_kva(&nsw_wcount_sync); 1547 else 1548 bp = getpbuf_kva(&nsw_wcount_async); 1549 bio = &bp->b_bio1; 1550 1551 pmap_qenter((vm_offset_t)bp->b_data, &m[i], n); 1552 1553 bp->b_bcount = PAGE_SIZE * n; 1554 bio->bio_offset = (off_t)blk << PAGE_SHIFT; 1555 1556 for (j = 0; j < n; ++j) { 1557 vm_page_t mreq = m[i+j]; 1558 1559 swp_pager_meta_build(mreq->object, mreq->pindex, 1560 blk + j); 1561 if (object->type == OBJT_SWAP) 1562 vm_page_dirty(mreq); 1563 rtvals[i+j] = VM_PAGER_OK; 1564 1565 vm_page_flag_set(mreq, PG_SWAPINPROG); 1566 bp->b_xio.xio_pages[j] = mreq; 1567 } 1568 bp->b_xio.xio_npages = n; 1569 1570 mycpu->gd_cnt.v_swapout++; 1571 mycpu->gd_cnt.v_swappgsout += bp->b_xio.xio_npages; 1572 1573 lwkt_reltoken(&vm_token); 1574 1575 bp->b_dirtyoff = 0; /* req'd for NFS */ 1576 bp->b_dirtyend = bp->b_bcount; /* req'd for NFS */ 1577 bp->b_cmd = BUF_CMD_WRITE; 1578 bio->bio_caller_info1.index = SWBIO_WRITE; 1579 1580 /* 1581 * asynchronous 1582 */ 1583 if (sync == FALSE) { 1584 bio->bio_done = swp_pager_async_iodone; 1585 BUF_KERNPROC(bp); 1586 vn_strategy(swapdev_vp, bio); 1587 1588 for (j = 0; j < n; ++j) 1589 rtvals[i+j] = VM_PAGER_PEND; 1590 continue; 1591 } 1592 1593 /* 1594 * Issue synchrnously. 1595 * 1596 * Wait for the sync I/O to complete, then update rtvals. 1597 * We just set the rtvals[] to VM_PAGER_PEND so we can call 1598 * our async completion routine at the end, thus avoiding a 1599 * double-free. 1600 */ 1601 bio->bio_caller_info1.index |= SWBIO_SYNC; 1602 bio->bio_done = biodone_sync; 1603 bio->bio_flags |= BIO_SYNC; 1604 vn_strategy(swapdev_vp, bio); 1605 biowait(bio, "swwrt"); 1606 1607 for (j = 0; j < n; ++j) 1608 rtvals[i+j] = VM_PAGER_PEND; 1609 1610 /* 1611 * Now that we are through with the bp, we can call the 1612 * normal async completion, which frees everything up. 1613 */ 1614 swp_pager_async_iodone(bio); 1615 } 1616 } 1617 1618 /* 1619 * No requirements. 1620 */ 1621 void 1622 swap_pager_newswap(void) 1623 { 1624 swp_sizecheck(); 1625 } 1626 1627 /* 1628 * swp_pager_async_iodone: 1629 * 1630 * Completion routine for asynchronous reads and writes from/to swap. 1631 * Also called manually by synchronous code to finish up a bp. 1632 * 1633 * For READ operations, the pages are PG_BUSY'd. For WRITE operations, 1634 * the pages are vm_page_t->busy'd. For READ operations, we PG_BUSY 1635 * unbusy all pages except the 'main' request page. For WRITE 1636 * operations, we vm_page_t->busy'd unbusy all pages ( we can do this 1637 * because we marked them all VM_PAGER_PEND on return from putpages ). 1638 * 1639 * This routine may not block. 1640 * 1641 * No requirements. 1642 */ 1643 static void 1644 swp_pager_async_iodone(struct bio *bio) 1645 { 1646 struct buf *bp = bio->bio_buf; 1647 vm_object_t object = NULL; 1648 int i; 1649 int *nswptr; 1650 1651 /* 1652 * report error 1653 */ 1654 if (bp->b_flags & B_ERROR) { 1655 kprintf( 1656 "swap_pager: I/O error - %s failed; offset %lld," 1657 "size %ld, error %d\n", 1658 ((bio->bio_caller_info1.index & SWBIO_READ) ? 1659 "pagein" : "pageout"), 1660 (long long)bio->bio_offset, 1661 (long)bp->b_bcount, 1662 bp->b_error 1663 ); 1664 } 1665 1666 /* 1667 * set object, raise to splvm(). 1668 */ 1669 if (bp->b_xio.xio_npages) 1670 object = bp->b_xio.xio_pages[0]->object; 1671 lwkt_gettoken(&vm_token); 1672 1673 /* 1674 * remove the mapping for kernel virtual 1675 */ 1676 pmap_qremove((vm_offset_t)bp->b_data, bp->b_xio.xio_npages); 1677 1678 /* 1679 * cleanup pages. If an error occurs writing to swap, we are in 1680 * very serious trouble. If it happens to be a disk error, though, 1681 * we may be able to recover by reassigning the swap later on. So 1682 * in this case we remove the m->swapblk assignment for the page 1683 * but do not free it in the rlist. The errornous block(s) are thus 1684 * never reallocated as swap. Redirty the page and continue. 1685 */ 1686 for (i = 0; i < bp->b_xio.xio_npages; ++i) { 1687 vm_page_t m = bp->b_xio.xio_pages[i]; 1688 1689 if (bp->b_flags & B_ERROR) { 1690 /* 1691 * If an error occurs I'd love to throw the swapblk 1692 * away without freeing it back to swapspace, so it 1693 * can never be used again. But I can't from an 1694 * interrupt. 1695 */ 1696 1697 if (bio->bio_caller_info1.index & SWBIO_READ) { 1698 /* 1699 * When reading, reqpage needs to stay 1700 * locked for the parent, but all other 1701 * pages can be freed. We still want to 1702 * wakeup the parent waiting on the page, 1703 * though. ( also: pg_reqpage can be -1 and 1704 * not match anything ). 1705 * 1706 * We have to wake specifically requested pages 1707 * up too because we cleared PG_SWAPINPROG and 1708 * someone may be waiting for that. 1709 * 1710 * NOTE: for reads, m->dirty will probably 1711 * be overridden by the original caller of 1712 * getpages so don't play cute tricks here. 1713 * 1714 * NOTE: We can't actually free the page from 1715 * here, because this is an interrupt. It 1716 * is not legal to mess with object->memq 1717 * from an interrupt. Deactivate the page 1718 * instead. 1719 */ 1720 1721 m->valid = 0; 1722 vm_page_flag_clear(m, PG_ZERO); 1723 vm_page_flag_clear(m, PG_SWAPINPROG); 1724 1725 /* 1726 * bio_driver_info holds the requested page 1727 * index. 1728 */ 1729 if (i != (int)(intptr_t)bio->bio_driver_info) { 1730 vm_page_deactivate(m); 1731 vm_page_wakeup(m); 1732 } else { 1733 vm_page_flash(m); 1734 } 1735 /* 1736 * If i == bp->b_pager.pg_reqpage, do not wake 1737 * the page up. The caller needs to. 1738 */ 1739 } else { 1740 /* 1741 * If a write error occurs remove the swap 1742 * assignment (note that PG_SWAPPED may or 1743 * may not be set depending on prior activity). 1744 * 1745 * Re-dirty OBJT_SWAP pages as there is no 1746 * other backing store, we can't throw the 1747 * page away. 1748 * 1749 * Non-OBJT_SWAP pages (aka swapcache) must 1750 * not be dirtied since they may not have 1751 * been dirty in the first place, and they 1752 * do have backing store (the vnode). 1753 */ 1754 swp_pager_meta_ctl(m->object, m->pindex, 1755 SWM_FREE); 1756 vm_page_flag_clear(m, PG_SWAPPED); 1757 if (m->object->type == OBJT_SWAP) { 1758 vm_page_dirty(m); 1759 vm_page_activate(m); 1760 } 1761 vm_page_flag_clear(m, PG_SWAPINPROG); 1762 vm_page_io_finish(m); 1763 } 1764 } else if (bio->bio_caller_info1.index & SWBIO_READ) { 1765 /* 1766 * NOTE: for reads, m->dirty will probably be 1767 * overridden by the original caller of getpages so 1768 * we cannot set them in order to free the underlying 1769 * swap in a low-swap situation. I don't think we'd 1770 * want to do that anyway, but it was an optimization 1771 * that existed in the old swapper for a time before 1772 * it got ripped out due to precisely this problem. 1773 * 1774 * clear PG_ZERO in page. 1775 * 1776 * If not the requested page then deactivate it. 1777 * 1778 * Note that the requested page, reqpage, is left 1779 * busied, but we still have to wake it up. The 1780 * other pages are released (unbusied) by 1781 * vm_page_wakeup(). We do not set reqpage's 1782 * valid bits here, it is up to the caller. 1783 */ 1784 1785 /* 1786 * NOTE: can't call pmap_clear_modify(m) from an 1787 * interrupt thread, the pmap code may have to map 1788 * non-kernel pmaps and currently asserts the case. 1789 */ 1790 /*pmap_clear_modify(m);*/ 1791 m->valid = VM_PAGE_BITS_ALL; 1792 vm_page_undirty(m); 1793 vm_page_flag_clear(m, PG_ZERO | PG_SWAPINPROG); 1794 vm_page_flag_set(m, PG_SWAPPED); 1795 1796 /* 1797 * We have to wake specifically requested pages 1798 * up too because we cleared PG_SWAPINPROG and 1799 * could be waiting for it in getpages. However, 1800 * be sure to not unbusy getpages specifically 1801 * requested page - getpages expects it to be 1802 * left busy. 1803 * 1804 * bio_driver_info holds the requested page 1805 */ 1806 if (i != (int)(intptr_t)bio->bio_driver_info) { 1807 vm_page_deactivate(m); 1808 vm_page_wakeup(m); 1809 } else { 1810 vm_page_flash(m); 1811 } 1812 } else { 1813 /* 1814 * Mark the page clean but do not mess with the 1815 * pmap-layer's modified state. That state should 1816 * also be clear since the caller protected the 1817 * page VM_PROT_READ, but allow the case. 1818 * 1819 * We are in an interrupt, avoid pmap operations. 1820 * 1821 * If we have a severe page deficit, deactivate the 1822 * page. Do not try to cache it (which would also 1823 * involve a pmap op), because the page might still 1824 * be read-heavy. 1825 * 1826 * When using the swap to cache clean vnode pages 1827 * we do not mess with the page dirty bits. 1828 */ 1829 if (m->object->type == OBJT_SWAP) 1830 vm_page_undirty(m); 1831 vm_page_flag_clear(m, PG_SWAPINPROG); 1832 vm_page_flag_set(m, PG_SWAPPED); 1833 if (vm_page_count_severe()) 1834 vm_page_deactivate(m); 1835 #if 0 1836 if (!vm_page_count_severe() || !vm_page_try_to_cache(m)) 1837 vm_page_protect(m, VM_PROT_READ); 1838 #endif 1839 vm_page_io_finish(m); 1840 } 1841 } 1842 1843 /* 1844 * adjust pip. NOTE: the original parent may still have its own 1845 * pip refs on the object. 1846 */ 1847 1848 if (object) 1849 vm_object_pip_wakeup_n(object, bp->b_xio.xio_npages); 1850 1851 /* 1852 * Release the physical I/O buffer. 1853 * 1854 * NOTE: Due to synchronous operations in the write case b_cmd may 1855 * already be set to BUF_CMD_DONE and BIO_SYNC may have already 1856 * been cleared. 1857 */ 1858 if (bio->bio_caller_info1.index & SWBIO_READ) 1859 nswptr = &nsw_rcount; 1860 else if (bio->bio_caller_info1.index & SWBIO_SYNC) 1861 nswptr = &nsw_wcount_sync; 1862 else 1863 nswptr = &nsw_wcount_async; 1864 bp->b_cmd = BUF_CMD_DONE; 1865 relpbuf(bp, nswptr); 1866 lwkt_reltoken(&vm_token); 1867 } 1868 1869 /* 1870 * Fault-in a potentially swapped page and remove the swap reference. 1871 */ 1872 static __inline void 1873 swp_pager_fault_page(vm_object_t object, vm_pindex_t pindex) 1874 { 1875 struct vnode *vp; 1876 vm_page_t m; 1877 int error; 1878 1879 if (object->type == OBJT_VNODE) { 1880 /* 1881 * Any swap related to a vnode is due to swapcache. We must 1882 * vget() the vnode in case it is not active (otherwise 1883 * vref() will panic). Calling vm_object_page_remove() will 1884 * ensure that any swap ref is removed interlocked with the 1885 * page. clean_only is set to TRUE so we don't throw away 1886 * dirty pages. 1887 */ 1888 vp = object->handle; 1889 error = vget(vp, LK_SHARED | LK_RETRY | LK_CANRECURSE); 1890 if (error == 0) { 1891 vm_object_page_remove(object, pindex, pindex + 1, TRUE); 1892 vput(vp); 1893 } 1894 } else { 1895 /* 1896 * Otherwise it is a normal OBJT_SWAP object and we can 1897 * fault the page in and remove the swap. 1898 */ 1899 m = vm_fault_object_page(object, IDX_TO_OFF(pindex), 1900 VM_PROT_NONE, 1901 VM_FAULT_DIRTY | VM_FAULT_UNSWAP, 1902 &error); 1903 if (m) 1904 vm_page_unhold(m); 1905 } 1906 } 1907 1908 int 1909 swap_pager_swapoff(int devidx) 1910 { 1911 vm_object_t object; 1912 struct swblock *swap; 1913 swblk_t v; 1914 int i; 1915 1916 lwkt_gettoken(&vm_token); 1917 lwkt_gettoken(&vmobj_token); 1918 rescan: 1919 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1920 if (object->type == OBJT_SWAP || object->type == OBJT_VNODE) { 1921 RB_FOREACH(swap, swblock_rb_tree, &object->swblock_root) { 1922 for (i = 0; i < SWAP_META_PAGES; ++i) { 1923 v = swap->swb_pages[i]; 1924 if (v != SWAPBLK_NONE && 1925 BLK2DEVIDX(v) == devidx) { 1926 swp_pager_fault_page( 1927 object, 1928 swap->swb_index + i); 1929 goto rescan; 1930 } 1931 } 1932 } 1933 } 1934 } 1935 lwkt_reltoken(&vmobj_token); 1936 lwkt_reltoken(&vm_token); 1937 1938 /* 1939 * If we fail to locate all swblocks we just fail gracefully and 1940 * do not bother to restore paging on the swap device. If the 1941 * user wants to retry the user can retry. 1942 */ 1943 if (swdevt[devidx].sw_nused) 1944 return (1); 1945 else 1946 return (0); 1947 } 1948 1949 /************************************************************************ 1950 * SWAP META DATA * 1951 ************************************************************************ 1952 * 1953 * These routines manipulate the swap metadata stored in the 1954 * OBJT_SWAP object. All swp_*() routines must be called at 1955 * splvm() because swap can be freed up by the low level vm_page 1956 * code which might be called from interrupts beyond what splbio() covers. 1957 * 1958 * Swap metadata is implemented with a global hash and not directly 1959 * linked into the object. Instead the object simply contains 1960 * appropriate tracking counters. 1961 */ 1962 1963 /* 1964 * Lookup the swblock containing the specified swap block index. 1965 * 1966 * The caller must hold vm_token. 1967 */ 1968 static __inline 1969 struct swblock * 1970 swp_pager_lookup(vm_object_t object, vm_pindex_t index) 1971 { 1972 index &= ~SWAP_META_MASK; 1973 return (RB_LOOKUP(swblock_rb_tree, &object->swblock_root, index)); 1974 } 1975 1976 /* 1977 * Remove a swblock from the RB tree. 1978 * 1979 * The caller must hold vm_token. 1980 */ 1981 static __inline 1982 void 1983 swp_pager_remove(vm_object_t object, struct swblock *swap) 1984 { 1985 RB_REMOVE(swblock_rb_tree, &object->swblock_root, swap); 1986 } 1987 1988 /* 1989 * Convert default object to swap object if necessary 1990 * 1991 * The caller must hold vm_token. 1992 */ 1993 static void 1994 swp_pager_meta_convert(vm_object_t object) 1995 { 1996 if (object->type == OBJT_DEFAULT) { 1997 object->type = OBJT_SWAP; 1998 KKASSERT(object->swblock_count == 0); 1999 } 2000 } 2001 2002 /* 2003 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 2004 * 2005 * We first convert the object to a swap object if it is a default 2006 * object. Vnode objects do not need to be converted. 2007 * 2008 * The specified swapblk is added to the object's swap metadata. If 2009 * the swapblk is not valid, it is freed instead. Any previously 2010 * assigned swapblk is freed. 2011 * 2012 * The caller must hold vm_token. 2013 */ 2014 static void 2015 swp_pager_meta_build(vm_object_t object, vm_pindex_t index, swblk_t swapblk) 2016 { 2017 struct swblock *swap; 2018 struct swblock *oswap; 2019 2020 KKASSERT(swapblk != SWAPBLK_NONE); 2021 2022 /* 2023 * Convert object if necessary 2024 */ 2025 if (object->type == OBJT_DEFAULT) 2026 swp_pager_meta_convert(object); 2027 2028 /* 2029 * Locate swblock. If not found create, but if we aren't adding 2030 * anything just return. If we run out of space in the map we wait 2031 * and, since the hash table may have changed, retry. 2032 */ 2033 retry: 2034 swap = swp_pager_lookup(object, index); 2035 2036 if (swap == NULL) { 2037 int i; 2038 2039 swap = zalloc(swap_zone); 2040 if (swap == NULL) { 2041 vm_wait(0); 2042 goto retry; 2043 } 2044 swap->swb_index = index & ~SWAP_META_MASK; 2045 swap->swb_count = 0; 2046 2047 ++object->swblock_count; 2048 2049 for (i = 0; i < SWAP_META_PAGES; ++i) 2050 swap->swb_pages[i] = SWAPBLK_NONE; 2051 oswap = RB_INSERT(swblock_rb_tree, &object->swblock_root, swap); 2052 KKASSERT(oswap == NULL); 2053 } 2054 2055 /* 2056 * Delete prior contents of metadata 2057 */ 2058 2059 index &= SWAP_META_MASK; 2060 2061 if (swap->swb_pages[index] != SWAPBLK_NONE) { 2062 swp_pager_freeswapspace(object, swap->swb_pages[index], 1); 2063 --swap->swb_count; 2064 } 2065 2066 /* 2067 * Enter block into metadata 2068 */ 2069 swap->swb_pages[index] = swapblk; 2070 if (swapblk != SWAPBLK_NONE) 2071 ++swap->swb_count; 2072 } 2073 2074 /* 2075 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2076 * 2077 * The requested range of blocks is freed, with any associated swap 2078 * returned to the swap bitmap. 2079 * 2080 * This routine will free swap metadata structures as they are cleaned 2081 * out. This routine does *NOT* operate on swap metadata associated 2082 * with resident pages. 2083 * 2084 * The caller must hold vm_token. 2085 */ 2086 static int swp_pager_meta_free_callback(struct swblock *swb, void *data); 2087 2088 static void 2089 swp_pager_meta_free(vm_object_t object, vm_pindex_t index, vm_pindex_t count) 2090 { 2091 struct swfreeinfo info; 2092 2093 /* 2094 * Nothing to do 2095 */ 2096 if (object->swblock_count == 0) { 2097 KKASSERT(RB_EMPTY(&object->swblock_root)); 2098 return; 2099 } 2100 if (count == 0) 2101 return; 2102 2103 /* 2104 * Setup for RB tree scan. Note that the pindex range can be huge 2105 * due to the 64 bit page index space so we cannot safely iterate. 2106 */ 2107 info.object = object; 2108 info.basei = index & ~SWAP_META_MASK; 2109 info.begi = index; 2110 info.endi = index + count - 1; 2111 swblock_rb_tree_RB_SCAN(&object->swblock_root, rb_swblock_scancmp, 2112 swp_pager_meta_free_callback, &info); 2113 } 2114 2115 /* 2116 * The caller must hold vm_token. 2117 */ 2118 static 2119 int 2120 swp_pager_meta_free_callback(struct swblock *swap, void *data) 2121 { 2122 struct swfreeinfo *info = data; 2123 vm_object_t object = info->object; 2124 int index; 2125 int eindex; 2126 2127 /* 2128 * Figure out the range within the swblock. The wider scan may 2129 * return edge-case swap blocks when the start and/or end points 2130 * are in the middle of a block. 2131 */ 2132 if (swap->swb_index < info->begi) 2133 index = (int)info->begi & SWAP_META_MASK; 2134 else 2135 index = 0; 2136 2137 if (swap->swb_index + SWAP_META_PAGES > info->endi) 2138 eindex = (int)info->endi & SWAP_META_MASK; 2139 else 2140 eindex = SWAP_META_MASK; 2141 2142 /* 2143 * Scan and free the blocks. The loop terminates early 2144 * if (swap) runs out of blocks and could be freed. 2145 */ 2146 while (index <= eindex) { 2147 swblk_t v = swap->swb_pages[index]; 2148 2149 if (v != SWAPBLK_NONE) { 2150 swp_pager_freeswapspace(object, v, 1); 2151 swap->swb_pages[index] = SWAPBLK_NONE; 2152 if (--swap->swb_count == 0) { 2153 swp_pager_remove(object, swap); 2154 zfree(swap_zone, swap); 2155 --object->swblock_count; 2156 break; 2157 } 2158 } 2159 ++index; 2160 } 2161 /* swap may be invalid here due to zfree above */ 2162 return(0); 2163 } 2164 2165 /* 2166 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2167 * 2168 * This routine locates and destroys all swap metadata associated with 2169 * an object. 2170 * 2171 * The caller must hold vm_token. 2172 */ 2173 static void 2174 swp_pager_meta_free_all(vm_object_t object) 2175 { 2176 struct swblock *swap; 2177 int i; 2178 2179 while ((swap = RB_ROOT(&object->swblock_root)) != NULL) { 2180 swp_pager_remove(object, swap); 2181 for (i = 0; i < SWAP_META_PAGES; ++i) { 2182 swblk_t v = swap->swb_pages[i]; 2183 if (v != SWAPBLK_NONE) { 2184 --swap->swb_count; 2185 swp_pager_freeswapspace(object, v, 1); 2186 } 2187 } 2188 if (swap->swb_count != 0) 2189 panic("swap_pager_meta_free_all: swb_count != 0"); 2190 zfree(swap_zone, swap); 2191 --object->swblock_count; 2192 } 2193 KKASSERT(object->swblock_count == 0); 2194 } 2195 2196 /* 2197 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. 2198 * 2199 * This routine is capable of looking up, popping, or freeing 2200 * swapblk assignments in the swap meta data or in the vm_page_t. 2201 * The routine typically returns the swapblk being looked-up, or popped, 2202 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block 2203 * was invalid. This routine will automatically free any invalid 2204 * meta-data swapblks. 2205 * 2206 * It is not possible to store invalid swapblks in the swap meta data 2207 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking. 2208 * 2209 * When acting on a busy resident page and paging is in progress, we 2210 * have to wait until paging is complete but otherwise can act on the 2211 * busy page. 2212 * 2213 * SWM_FREE remove and free swap block from metadata 2214 * SWM_POP remove from meta data but do not free.. pop it out 2215 * 2216 * The caller must hold vm_token. 2217 */ 2218 static swblk_t 2219 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t index, int flags) 2220 { 2221 struct swblock *swap; 2222 swblk_t r1; 2223 2224 if (object->swblock_count == 0) 2225 return(SWAPBLK_NONE); 2226 2227 r1 = SWAPBLK_NONE; 2228 swap = swp_pager_lookup(object, index); 2229 2230 if (swap != NULL) { 2231 index &= SWAP_META_MASK; 2232 r1 = swap->swb_pages[index]; 2233 2234 if (r1 != SWAPBLK_NONE) { 2235 if (flags & SWM_FREE) { 2236 swp_pager_freeswapspace(object, r1, 1); 2237 r1 = SWAPBLK_NONE; 2238 } 2239 if (flags & (SWM_FREE|SWM_POP)) { 2240 swap->swb_pages[index] = SWAPBLK_NONE; 2241 if (--swap->swb_count == 0) { 2242 swp_pager_remove(object, swap); 2243 zfree(swap_zone, swap); 2244 --object->swblock_count; 2245 } 2246 } 2247 } 2248 } 2249 return(r1); 2250 } 2251