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. Neither the name of the University nor the names of its contributors 54 * may be used to endorse or promote products derived from this software 55 * without specific prior written permission. 56 * 57 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 58 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 59 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 60 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 61 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 62 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 63 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 64 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 65 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 66 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 67 * SUCH DAMAGE. 68 * 69 * New Swap System 70 * Matthew Dillon 71 * 72 * Radix Bitmap 'blists'. 73 * 74 * - The new swapper uses the new radix bitmap code. This should scale 75 * to arbitrarily small or arbitrarily large swap spaces and an almost 76 * arbitrary degree of fragmentation. 77 * 78 * Features: 79 * 80 * - on the fly reallocation of swap during putpages. The new system 81 * does not try to keep previously allocated swap blocks for dirty 82 * pages. 83 * 84 * - on the fly deallocation of swap 85 * 86 * - No more garbage collection required. Unnecessarily allocated swap 87 * blocks only exist for dirty vm_page_t's now and these are already 88 * cycled (in a high-load system) by the pager. We also do on-the-fly 89 * removal of invalidated swap blocks when a page is destroyed 90 * or renamed. 91 * 92 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$ 93 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94 94 * $FreeBSD: src/sys/vm/swap_pager.c,v 1.130.2.12 2002/08/31 21:15:55 dillon Exp $ 95 */ 96 97 #include <sys/param.h> 98 #include <sys/systm.h> 99 #include <sys/conf.h> 100 #include <sys/kernel.h> 101 #include <sys/proc.h> 102 #include <sys/buf.h> 103 #include <sys/vnode.h> 104 #include <sys/malloc.h> 105 #include <sys/vmmeter.h> 106 #include <sys/sysctl.h> 107 #include <sys/blist.h> 108 #include <sys/lock.h> 109 #include <sys/thread2.h> 110 111 #include "opt_swap.h" 112 #include <vm/vm.h> 113 #include <vm/vm_object.h> 114 #include <vm/vm_page.h> 115 #include <vm/vm_pager.h> 116 #include <vm/vm_pageout.h> 117 #include <vm/swap_pager.h> 118 #include <vm/vm_extern.h> 119 #include <vm/vm_zone.h> 120 #include <vm/vnode_pager.h> 121 122 #include <sys/buf2.h> 123 #include <vm/vm_page2.h> 124 125 #ifndef MAX_PAGEOUT_CLUSTER 126 #define MAX_PAGEOUT_CLUSTER SWB_NPAGES 127 #endif 128 129 #define SWM_FREE 0x02 /* free, period */ 130 #define SWM_POP 0x04 /* pop out */ 131 132 #define SWBIO_READ 0x01 133 #define SWBIO_WRITE 0x02 134 #define SWBIO_SYNC 0x04 135 #define SWBIO_TTC 0x08 /* for VM_PAGER_TRY_TO_CACHE */ 136 137 struct swfreeinfo { 138 vm_object_t object; 139 vm_pindex_t basei; 140 vm_pindex_t begi; 141 vm_pindex_t endi; /* inclusive */ 142 }; 143 144 struct swswapoffinfo { 145 vm_object_t object; 146 int devidx; 147 int shared; 148 }; 149 150 /* 151 * vm_swap_size is in page-sized chunks now. It was DEV_BSIZE'd chunks 152 * in the old system. 153 */ 154 155 int swap_pager_full; /* swap space exhaustion (task killing) */ 156 int swap_fail_ticks; /* when we became exhausted */ 157 int swap_pager_almost_full; /* swap space exhaustion (w/ hysteresis)*/ 158 swblk_t vm_swap_cache_use; 159 swblk_t vm_swap_anon_use; 160 static int vm_report_swap_allocs; 161 162 static int nsw_rcount; /* free read buffers */ 163 static int nsw_wcount_sync; /* limit write buffers / synchronous */ 164 static int nsw_wcount_async; /* limit write buffers / asynchronous */ 165 static int nsw_wcount_async_max;/* assigned maximum */ 166 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 167 168 struct blist *swapblist; 169 static int swap_async_max = 4; /* maximum in-progress async I/O's */ 170 static int swap_burst_read = 0; /* allow burst reading */ 171 static swblk_t swapiterator; /* linearize allocations */ 172 int swap_user_async = 0; /* user swap pager operation can be async */ 173 174 static struct spinlock swapbp_spin = SPINLOCK_INITIALIZER(&swapbp_spin, "swapbp_spin"); 175 176 /* from vm_swap.c */ 177 extern struct vnode *swapdev_vp; 178 extern struct swdevt *swdevt; 179 extern int nswdev; 180 181 #define BLK2DEVIDX(blk) (nswdev > 1 ? blk / SWB_DMMAX % nswdev : 0) 182 183 SYSCTL_INT(_vm, OID_AUTO, swap_async_max, 184 CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops"); 185 SYSCTL_INT(_vm, OID_AUTO, swap_burst_read, 186 CTLFLAG_RW, &swap_burst_read, 0, "Allow burst reads for pageins"); 187 SYSCTL_INT(_vm, OID_AUTO, swap_user_async, 188 CTLFLAG_RW, &swap_user_async, 0, "Allow async uuser swap write I/O"); 189 190 #if SWBLK_BITS == 64 191 SYSCTL_LONG(_vm, OID_AUTO, swap_cache_use, 192 CTLFLAG_RD, &vm_swap_cache_use, 0, ""); 193 SYSCTL_LONG(_vm, OID_AUTO, swap_anon_use, 194 CTLFLAG_RD, &vm_swap_anon_use, 0, ""); 195 SYSCTL_LONG(_vm, OID_AUTO, swap_size, 196 CTLFLAG_RD, &vm_swap_size, 0, ""); 197 #else 198 SYSCTL_INT(_vm, OID_AUTO, swap_cache_use, 199 CTLFLAG_RD, &vm_swap_cache_use, 0, ""); 200 SYSCTL_INT(_vm, OID_AUTO, swap_anon_use, 201 CTLFLAG_RD, &vm_swap_anon_use, 0, ""); 202 SYSCTL_INT(_vm, OID_AUTO, swap_size, 203 CTLFLAG_RD, &vm_swap_size, 0, ""); 204 #endif 205 SYSCTL_INT(_vm, OID_AUTO, report_swap_allocs, 206 CTLFLAG_RW, &vm_report_swap_allocs, 0, ""); 207 208 vm_zone_t swap_zone; 209 210 /* 211 * Red-Black tree for swblock entries 212 * 213 * The caller must hold vm_token 214 */ 215 RB_GENERATE2(swblock_rb_tree, swblock, swb_entry, rb_swblock_compare, 216 vm_pindex_t, swb_index); 217 218 int 219 rb_swblock_compare(struct swblock *swb1, struct swblock *swb2) 220 { 221 if (swb1->swb_index < swb2->swb_index) 222 return(-1); 223 if (swb1->swb_index > swb2->swb_index) 224 return(1); 225 return(0); 226 } 227 228 static 229 int 230 rb_swblock_scancmp(struct swblock *swb, void *data) 231 { 232 struct swfreeinfo *info = data; 233 234 if (swb->swb_index < info->basei) 235 return(-1); 236 if (swb->swb_index > info->endi) 237 return(1); 238 return(0); 239 } 240 241 static 242 int 243 rb_swblock_condcmp(struct swblock *swb, void *data) 244 { 245 struct swfreeinfo *info = data; 246 247 if (swb->swb_index < info->basei) 248 return(-1); 249 return(0); 250 } 251 252 /* 253 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 254 * calls hooked from other parts of the VM system and do not appear here. 255 * (see vm/swap_pager.h). 256 */ 257 258 static void swap_pager_dealloc (vm_object_t object); 259 static int swap_pager_getpage (vm_object_t, vm_page_t *, int); 260 static void swap_chain_iodone(struct bio *biox); 261 262 struct pagerops swappagerops = { 263 swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 264 swap_pager_getpage, /* pagein */ 265 swap_pager_putpages, /* pageout */ 266 swap_pager_haspage /* get backing store status for page */ 267 }; 268 269 /* 270 * SWB_DMMAX is in page-sized chunks with the new swap system. It was 271 * dev-bsized chunks in the old. SWB_DMMAX is always a power of 2. 272 * 273 * swap_*() routines are externally accessible. swp_*() routines are 274 * internal. 275 */ 276 277 int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 278 int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 279 280 static __inline void swp_sizecheck (void); 281 static void swp_pager_async_iodone (struct bio *bio); 282 283 /* 284 * Swap bitmap functions 285 */ 286 287 static __inline void swp_pager_freeswapspace(vm_object_t object, 288 swblk_t blk, int npages); 289 static __inline swblk_t swp_pager_getswapspace(vm_object_t object, int npages); 290 291 /* 292 * Metadata functions 293 */ 294 295 static void swp_pager_meta_convert(vm_object_t); 296 static void swp_pager_meta_build(vm_object_t, vm_pindex_t, swblk_t); 297 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 298 static void swp_pager_meta_free_all(vm_object_t); 299 static swblk_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 300 301 /* 302 * SWP_SIZECHECK() - update swap_pager_full indication 303 * 304 * update the swap_pager_almost_full indication and warn when we are 305 * about to run out of swap space, using lowat/hiwat hysteresis. 306 * 307 * Clear swap_pager_full ( task killing ) indication when lowat is met. 308 * 309 * No restrictions on call 310 * This routine may not block. 311 * SMP races are ok. 312 */ 313 static __inline void 314 swp_sizecheck(void) 315 { 316 if (vm_swap_size < nswap_lowat) { 317 if (swap_pager_almost_full == 0) { 318 kprintf("swap_pager: out of swap space\n"); 319 swap_pager_almost_full = 1; 320 swap_fail_ticks = ticks; 321 } 322 } else { 323 swap_pager_full = 0; 324 if (vm_swap_size > nswap_hiwat) 325 swap_pager_almost_full = 0; 326 } 327 } 328 329 /* 330 * SWAP_PAGER_INIT() - initialize the swap pager! 331 * 332 * Expected to be started from system init. NOTE: This code is run 333 * before much else so be careful what you depend on. Most of the VM 334 * system has yet to be initialized at this point. 335 * 336 * Called from the low level boot code only. 337 */ 338 static void 339 swap_pager_init(void *arg __unused) 340 { 341 } 342 SYSINIT(vm_mem, SI_BOOT1_VM, SI_ORDER_THIRD, swap_pager_init, NULL); 343 344 /* 345 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 346 * 347 * Expected to be started from pageout process once, prior to entering 348 * its main loop. 349 * 350 * Called from the low level boot code only. 351 */ 352 void 353 swap_pager_swap_init(void) 354 { 355 int n, n2; 356 357 /* 358 * Number of in-transit swap bp operations. Don't 359 * exhaust the pbufs completely. Make sure we 360 * initialize workable values (0 will work for hysteresis 361 * but it isn't very efficient). 362 * 363 * The nsw_cluster_max is constrained by the number of pages an XIO 364 * holds, i.e., (MAXPHYS/PAGE_SIZE) and our locally defined 365 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 366 * constrained by the swap device interleave stripe size. 367 * 368 * Currently we hardwire nsw_wcount_async to 4. This limit is 369 * designed to prevent other I/O from having high latencies due to 370 * our pageout I/O. The value 4 works well for one or two active swap 371 * devices but is probably a little low if you have more. Even so, 372 * a higher value would probably generate only a limited improvement 373 * with three or four active swap devices since the system does not 374 * typically have to pageout at extreme bandwidths. We will want 375 * at least 2 per swap devices, and 4 is a pretty good value if you 376 * have one NFS swap device due to the command/ack latency over NFS. 377 * So it all works out pretty well. 378 */ 379 380 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER); 381 382 nsw_rcount = (nswbuf_kva + 1) / 2; 383 nsw_wcount_sync = (nswbuf_kva + 3) / 4; 384 nsw_wcount_async = 4; 385 nsw_wcount_async_max = nsw_wcount_async; 386 387 /* 388 * The zone is dynamically allocated so generally size it to 389 * maxswzone (32MB to 256GB of KVM). Set a minimum size based 390 * on physical memory of around 8x (each swblock can hold 16 pages). 391 * 392 * With the advent of SSDs (vs HDs) the practical (swap:memory) ratio 393 * has increased dramatically. 394 */ 395 n = vmstats.v_page_count / 2; 396 if (maxswzone && n < maxswzone / sizeof(struct swblock)) 397 n = maxswzone / sizeof(struct swblock); 398 n2 = n; 399 400 do { 401 swap_zone = zinit( 402 "SWAPMETA", 403 sizeof(struct swblock), 404 n, 405 ZONE_INTERRUPT); 406 if (swap_zone != NULL) 407 break; 408 /* 409 * if the allocation failed, try a zone two thirds the 410 * size of the previous attempt. 411 */ 412 n -= ((n + 2) / 3); 413 } while (n > 0); 414 415 if (swap_zone == NULL) 416 panic("swap_pager_swap_init: swap_zone == NULL"); 417 if (n2 != n) 418 kprintf("Swap zone entries reduced from %d to %d.\n", n2, n); 419 } 420 421 /* 422 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 423 * its metadata structures. 424 * 425 * This routine is called from the mmap and fork code to create a new 426 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object 427 * and then converting it with swp_pager_meta_convert(). 428 * 429 * We only support unnamed objects. 430 * 431 * No restrictions. 432 */ 433 vm_object_t 434 swap_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t offset) 435 { 436 vm_object_t object; 437 438 KKASSERT(handle == NULL); 439 object = vm_object_allocate_hold(OBJT_DEFAULT, 440 OFF_TO_IDX(offset + PAGE_MASK + size)); 441 swp_pager_meta_convert(object); 442 vm_object_drop(object); 443 444 return (object); 445 } 446 447 /* 448 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 449 * 450 * The swap backing for the object is destroyed. The code is 451 * designed such that we can reinstantiate it later, but this 452 * routine is typically called only when the entire object is 453 * about to be destroyed. 454 * 455 * The object must be locked or unreferenceable. 456 * No other requirements. 457 */ 458 static void 459 swap_pager_dealloc(vm_object_t object) 460 { 461 vm_object_hold(object); 462 vm_object_pip_wait(object, "swpdea"); 463 464 /* 465 * Free all remaining metadata. We only bother to free it from 466 * the swap meta data. We do not attempt to free swapblk's still 467 * associated with vm_page_t's for this object. We do not care 468 * if paging is still in progress on some objects. 469 */ 470 swp_pager_meta_free_all(object); 471 vm_object_drop(object); 472 } 473 474 /************************************************************************ 475 * SWAP PAGER BITMAP ROUTINES * 476 ************************************************************************/ 477 478 /* 479 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 480 * 481 * Allocate swap for the requested number of pages. The starting 482 * swap block number (a page index) is returned or SWAPBLK_NONE 483 * if the allocation failed. 484 * 485 * Also has the side effect of advising that somebody made a mistake 486 * when they configured swap and didn't configure enough. 487 * 488 * The caller must hold the object. 489 * This routine may not block. 490 */ 491 static __inline swblk_t 492 swp_pager_getswapspace(vm_object_t object, int npages) 493 { 494 swblk_t blk; 495 496 lwkt_gettoken(&vm_token); 497 blk = blist_allocat(swapblist, npages, swapiterator); 498 if (blk == SWAPBLK_NONE) 499 blk = blist_allocat(swapblist, npages, 0); 500 if (blk == SWAPBLK_NONE) { 501 if (swap_pager_full != 2) { 502 if (vm_swap_max == 0) 503 kprintf("Warning: The system would like to " 504 "page to swap but no swap space " 505 "is configured!\n"); 506 else 507 kprintf("swap_pager_getswapspace: " 508 "swap full allocating %d pages\n", 509 npages); 510 swap_pager_full = 2; 511 if (swap_pager_almost_full == 0) 512 swap_fail_ticks = ticks; 513 swap_pager_almost_full = 1; 514 } 515 } else { 516 /* swapiterator = blk; disable for now, doesn't work well */ 517 swapacctspace(blk, -npages); 518 if (object->type == OBJT_SWAP) 519 vm_swap_anon_use += npages; 520 else 521 vm_swap_cache_use += npages; 522 swp_sizecheck(); 523 } 524 lwkt_reltoken(&vm_token); 525 return(blk); 526 } 527 528 /* 529 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 530 * 531 * This routine returns the specified swap blocks back to the bitmap. 532 * 533 * Note: This routine may not block (it could in the old swap code), 534 * and through the use of the new blist routines it does not block. 535 * 536 * This routine may not block. 537 */ 538 539 static __inline void 540 swp_pager_freeswapspace(vm_object_t object, swblk_t blk, int npages) 541 { 542 struct swdevt *sp = &swdevt[BLK2DEVIDX(blk)]; 543 544 lwkt_gettoken(&vm_token); 545 sp->sw_nused -= npages; 546 if (object->type == OBJT_SWAP) 547 vm_swap_anon_use -= npages; 548 else 549 vm_swap_cache_use -= npages; 550 551 if (sp->sw_flags & SW_CLOSING) { 552 lwkt_reltoken(&vm_token); 553 return; 554 } 555 556 blist_free(swapblist, blk, npages); 557 vm_swap_size += npages; 558 swp_sizecheck(); 559 lwkt_reltoken(&vm_token); 560 } 561 562 /* 563 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 564 * range within an object. 565 * 566 * This is a globally accessible routine. 567 * 568 * This routine removes swapblk assignments from swap metadata. 569 * 570 * The external callers of this routine typically have already destroyed 571 * or renamed vm_page_t's associated with this range in the object so 572 * we should be ok. 573 * 574 * No requirements. 575 */ 576 void 577 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_pindex_t size) 578 { 579 vm_object_hold(object); 580 swp_pager_meta_free(object, start, size); 581 vm_object_drop(object); 582 } 583 584 /* 585 * No requirements. 586 */ 587 void 588 swap_pager_freespace_all(vm_object_t object) 589 { 590 vm_object_hold(object); 591 swp_pager_meta_free_all(object); 592 vm_object_drop(object); 593 } 594 595 /* 596 * This function conditionally frees swap cache swap starting at 597 * (*basei) in the object. (count) swap blocks will be nominally freed. 598 * The actual number of blocks freed can be more or less than the 599 * requested number. 600 * 601 * This function nominally returns the number of blocks freed. However, 602 * the actual number of blocks freed may be less then the returned value. 603 * If the function is unable to exhaust the object or if it is able to 604 * free (approximately) the requested number of blocks it returns 605 * a value n > count. 606 * 607 * If we exhaust the object we will return a value n <= count. 608 * 609 * The caller must hold the object. 610 * 611 * WARNING! If count == 0 then -1 can be returned as a degenerate case, 612 * callers should always pass a count value > 0. 613 */ 614 static int swap_pager_condfree_callback(struct swblock *swap, void *data); 615 616 int 617 swap_pager_condfree(vm_object_t object, vm_pindex_t *basei, int count) 618 { 619 struct swfreeinfo info; 620 int n; 621 int t; 622 623 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 624 625 info.object = object; 626 info.basei = *basei; /* skip up to this page index */ 627 info.begi = count; /* max swap pages to destroy */ 628 info.endi = count * 8; /* max swblocks to scan */ 629 630 swblock_rb_tree_RB_SCAN(&object->swblock_root, rb_swblock_condcmp, 631 swap_pager_condfree_callback, &info); 632 *basei = info.basei; 633 634 /* 635 * Take the higher difference swblocks vs pages 636 */ 637 n = count - (int)info.begi; 638 t = count * 8 - (int)info.endi; 639 if (n < t) 640 n = t; 641 if (n < 1) 642 n = 1; 643 return(n); 644 } 645 646 /* 647 * The idea is to free whole meta-block to avoid fragmenting 648 * the swap space or disk I/O. We only do this if NO VM pages 649 * are present. 650 * 651 * We do not have to deal with clearing PG_SWAPPED in related VM 652 * pages because there are no related VM pages. 653 * 654 * The caller must hold the object. 655 */ 656 static int 657 swap_pager_condfree_callback(struct swblock *swap, void *data) 658 { 659 struct swfreeinfo *info = data; 660 vm_object_t object = info->object; 661 int i; 662 663 for (i = 0; i < SWAP_META_PAGES; ++i) { 664 if (vm_page_lookup(object, swap->swb_index + i)) 665 break; 666 } 667 info->basei = swap->swb_index + SWAP_META_PAGES; 668 if (i == SWAP_META_PAGES) { 669 info->begi -= swap->swb_count; 670 swap_pager_freespace(object, swap->swb_index, SWAP_META_PAGES); 671 } 672 --info->endi; 673 if ((int)info->begi < 0 || (int)info->endi < 0) 674 return(-1); 675 lwkt_yield(); 676 return(0); 677 } 678 679 /* 680 * Called by vm_page_alloc() when a new VM page is inserted 681 * into a VM object. Checks whether swap has been assigned to 682 * the page and sets PG_SWAPPED as necessary. 683 * 684 * No requirements. 685 */ 686 void 687 swap_pager_page_inserted(vm_page_t m) 688 { 689 if (m->object->swblock_count) { 690 vm_object_hold(m->object); 691 if (swp_pager_meta_ctl(m->object, m->pindex, 0) != SWAPBLK_NONE) 692 vm_page_flag_set(m, PG_SWAPPED); 693 vm_object_drop(m->object); 694 } 695 } 696 697 /* 698 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 699 * 700 * Assigns swap blocks to the specified range within the object. The 701 * swap blocks are not zerod. Any previous swap assignment is destroyed. 702 * 703 * Returns 0 on success, -1 on failure. 704 * 705 * The caller is responsible for avoiding races in the specified range. 706 * No other requirements. 707 */ 708 int 709 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 710 { 711 int n = 0; 712 swblk_t blk = SWAPBLK_NONE; 713 vm_pindex_t beg = start; /* save start index */ 714 715 vm_object_hold(object); 716 717 while (size) { 718 if (n == 0) { 719 n = BLIST_MAX_ALLOC; 720 while ((blk = swp_pager_getswapspace(object, n)) == 721 SWAPBLK_NONE) 722 { 723 n >>= 1; 724 if (n == 0) { 725 swp_pager_meta_free(object, beg, 726 start - beg); 727 vm_object_drop(object); 728 return(-1); 729 } 730 } 731 } 732 swp_pager_meta_build(object, start, blk); 733 --size; 734 ++start; 735 ++blk; 736 --n; 737 } 738 swp_pager_meta_free(object, start, n); 739 vm_object_drop(object); 740 return(0); 741 } 742 743 /* 744 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 745 * and destroy the source. 746 * 747 * Copy any valid swapblks from the source to the destination. In 748 * cases where both the source and destination have a valid swapblk, 749 * we keep the destination's. 750 * 751 * This routine is allowed to block. It may block allocating metadata 752 * indirectly through swp_pager_meta_build() or if paging is still in 753 * progress on the source. 754 * 755 * XXX vm_page_collapse() kinda expects us not to block because we 756 * supposedly do not need to allocate memory, but for the moment we 757 * *may* have to get a little memory from the zone allocator, but 758 * it is taken from the interrupt memory. We should be ok. 759 * 760 * The source object contains no vm_page_t's (which is just as well) 761 * The source object is of type OBJT_SWAP. 762 * 763 * The source and destination objects must be held by the caller. 764 */ 765 void 766 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 767 vm_pindex_t base_index, int destroysource) 768 { 769 vm_pindex_t i; 770 771 ASSERT_LWKT_TOKEN_HELD(vm_object_token(srcobject)); 772 ASSERT_LWKT_TOKEN_HELD(vm_object_token(dstobject)); 773 774 /* 775 * transfer source to destination. 776 */ 777 for (i = 0; i < dstobject->size; ++i) { 778 swblk_t dstaddr; 779 780 /* 781 * Locate (without changing) the swapblk on the destination, 782 * unless it is invalid in which case free it silently, or 783 * if the destination is a resident page, in which case the 784 * source is thrown away. 785 */ 786 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 787 788 if (dstaddr == SWAPBLK_NONE) { 789 /* 790 * Destination has no swapblk and is not resident, 791 * copy source. 792 */ 793 swblk_t srcaddr; 794 795 srcaddr = swp_pager_meta_ctl(srcobject, 796 base_index + i, SWM_POP); 797 798 if (srcaddr != SWAPBLK_NONE) 799 swp_pager_meta_build(dstobject, i, srcaddr); 800 } else { 801 /* 802 * Destination has valid swapblk or it is represented 803 * by a resident page. We destroy the sourceblock. 804 */ 805 swp_pager_meta_ctl(srcobject, base_index + i, SWM_FREE); 806 } 807 } 808 809 /* 810 * Free left over swap blocks in source. 811 * 812 * We have to revert the type to OBJT_DEFAULT so we do not accidently 813 * double-remove the object from the swap queues. 814 */ 815 if (destroysource) { 816 /* 817 * Reverting the type is not necessary, the caller is going 818 * to destroy srcobject directly, but I'm doing it here 819 * for consistency since we've removed the object from its 820 * queues. 821 */ 822 swp_pager_meta_free_all(srcobject); 823 if (srcobject->type == OBJT_SWAP) 824 srcobject->type = OBJT_DEFAULT; 825 } 826 } 827 828 /* 829 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 830 * the requested page. 831 * 832 * We determine whether good backing store exists for the requested 833 * page and return TRUE if it does, FALSE if it doesn't. 834 * 835 * If TRUE, we also try to determine how much valid, contiguous backing 836 * store exists before and after the requested page within a reasonable 837 * distance. We do not try to restrict it to the swap device stripe 838 * (that is handled in getpages/putpages). It probably isn't worth 839 * doing here. 840 * 841 * No requirements. 842 */ 843 boolean_t 844 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex) 845 { 846 swblk_t blk0; 847 848 /* 849 * do we have good backing store at the requested index ? 850 */ 851 vm_object_hold(object); 852 blk0 = swp_pager_meta_ctl(object, pindex, 0); 853 854 if (blk0 == SWAPBLK_NONE) { 855 vm_object_drop(object); 856 return (FALSE); 857 } 858 vm_object_drop(object); 859 return (TRUE); 860 } 861 862 /* 863 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 864 * 865 * This removes any associated swap backing store, whether valid or 866 * not, from the page. This operates on any VM object, not just OBJT_SWAP 867 * objects. 868 * 869 * This routine is typically called when a page is made dirty, at 870 * which point any associated swap can be freed. MADV_FREE also 871 * calls us in a special-case situation 872 * 873 * NOTE!!! If the page is clean and the swap was valid, the caller 874 * should make the page dirty before calling this routine. This routine 875 * does NOT change the m->dirty status of the page. Also: MADV_FREE 876 * depends on it. 877 * 878 * The page must be busied or soft-busied. 879 * The caller can hold the object to avoid blocking, else we might block. 880 * No other requirements. 881 */ 882 void 883 swap_pager_unswapped(vm_page_t m) 884 { 885 if (m->flags & PG_SWAPPED) { 886 vm_object_hold(m->object); 887 KKASSERT(m->flags & PG_SWAPPED); 888 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); 889 vm_page_flag_clear(m, PG_SWAPPED); 890 vm_object_drop(m->object); 891 } 892 } 893 894 /* 895 * SWAP_PAGER_STRATEGY() - read, write, free blocks 896 * 897 * This implements a VM OBJECT strategy function using swap backing store. 898 * This can operate on any VM OBJECT type, not necessarily just OBJT_SWAP 899 * types. 900 * 901 * This is intended to be a cacheless interface (i.e. caching occurs at 902 * higher levels), and is also used as a swap-based SSD cache for vnode 903 * and device objects. 904 * 905 * All I/O goes directly to and from the swap device. 906 * 907 * We currently attempt to run I/O synchronously or asynchronously as 908 * the caller requests. This isn't perfect because we loose error 909 * sequencing when we run multiple ops in parallel to satisfy a request. 910 * But this is swap, so we let it all hang out. 911 * 912 * No requirements. 913 */ 914 void 915 swap_pager_strategy(vm_object_t object, struct bio *bio) 916 { 917 struct buf *bp = bio->bio_buf; 918 struct bio *nbio; 919 vm_pindex_t start; 920 vm_pindex_t biox_blkno = 0; 921 int count; 922 char *data; 923 struct bio *biox; 924 struct buf *bufx; 925 #if 0 926 struct bio_track *track; 927 #endif 928 929 #if 0 930 /* 931 * tracking for swapdev vnode I/Os 932 */ 933 if (bp->b_cmd == BUF_CMD_READ) 934 track = &swapdev_vp->v_track_read; 935 else 936 track = &swapdev_vp->v_track_write; 937 #endif 938 939 if (bp->b_bcount & PAGE_MASK) { 940 bp->b_error = EINVAL; 941 bp->b_flags |= B_ERROR | B_INVAL; 942 biodone(bio); 943 kprintf("swap_pager_strategy: bp %p offset %lld size %d, " 944 "not page bounded\n", 945 bp, (long long)bio->bio_offset, (int)bp->b_bcount); 946 return; 947 } 948 949 /* 950 * Clear error indication, initialize page index, count, data pointer. 951 */ 952 bp->b_error = 0; 953 bp->b_flags &= ~B_ERROR; 954 bp->b_resid = bp->b_bcount; 955 956 start = (vm_pindex_t)(bio->bio_offset >> PAGE_SHIFT); 957 count = howmany(bp->b_bcount, PAGE_SIZE); 958 data = bp->b_data; 959 960 /* 961 * Deal with BUF_CMD_FREEBLKS 962 */ 963 if (bp->b_cmd == BUF_CMD_FREEBLKS) { 964 /* 965 * FREE PAGE(s) - destroy underlying swap that is no longer 966 * needed. 967 */ 968 vm_object_hold(object); 969 swp_pager_meta_free(object, start, count); 970 vm_object_drop(object); 971 bp->b_resid = 0; 972 biodone(bio); 973 return; 974 } 975 976 /* 977 * We need to be able to create a new cluster of I/O's. We cannot 978 * use the caller fields of the passed bio so push a new one. 979 * 980 * Because nbio is just a placeholder for the cluster links, 981 * we can biodone() the original bio instead of nbio to make 982 * things a bit more efficient. 983 */ 984 nbio = push_bio(bio); 985 nbio->bio_offset = bio->bio_offset; 986 nbio->bio_caller_info1.cluster_head = NULL; 987 nbio->bio_caller_info2.cluster_tail = NULL; 988 989 biox = NULL; 990 bufx = NULL; 991 992 /* 993 * Execute read or write 994 */ 995 vm_object_hold(object); 996 997 while (count > 0) { 998 swblk_t blk; 999 1000 /* 1001 * Obtain block. If block not found and writing, allocate a 1002 * new block and build it into the object. 1003 */ 1004 blk = swp_pager_meta_ctl(object, start, 0); 1005 if ((blk == SWAPBLK_NONE) && bp->b_cmd != BUF_CMD_READ) { 1006 blk = swp_pager_getswapspace(object, 1); 1007 if (blk == SWAPBLK_NONE) { 1008 bp->b_error = ENOMEM; 1009 bp->b_flags |= B_ERROR; 1010 break; 1011 } 1012 swp_pager_meta_build(object, start, blk); 1013 } 1014 1015 /* 1016 * Do we have to flush our current collection? Yes if: 1017 * 1018 * - no swap block at this index 1019 * - swap block is not contiguous 1020 * - we cross a physical disk boundry in the 1021 * stripe. 1022 */ 1023 if ( 1024 biox && (biox_blkno + btoc(bufx->b_bcount) != blk || 1025 ((biox_blkno ^ blk) & ~SWB_DMMASK) 1026 ) 1027 ) { 1028 if (bp->b_cmd == BUF_CMD_READ) { 1029 ++mycpu->gd_cnt.v_swapin; 1030 mycpu->gd_cnt.v_swappgsin += btoc(bufx->b_bcount); 1031 } else { 1032 ++mycpu->gd_cnt.v_swapout; 1033 mycpu->gd_cnt.v_swappgsout += btoc(bufx->b_bcount); 1034 bufx->b_dirtyend = bufx->b_bcount; 1035 } 1036 1037 /* 1038 * Finished with this buf. 1039 */ 1040 KKASSERT(bufx->b_bcount != 0); 1041 if (bufx->b_cmd != BUF_CMD_READ) 1042 bufx->b_dirtyend = bufx->b_bcount; 1043 biox = NULL; 1044 bufx = NULL; 1045 } 1046 1047 /* 1048 * Add new swapblk to biox, instantiating biox if necessary. 1049 * Zero-fill reads are able to take a shortcut. 1050 */ 1051 if (blk == SWAPBLK_NONE) { 1052 /* 1053 * We can only get here if we are reading. 1054 */ 1055 bzero(data, PAGE_SIZE); 1056 bp->b_resid -= PAGE_SIZE; 1057 } else { 1058 if (biox == NULL) { 1059 /* XXX chain count > 4, wait to <= 4 */ 1060 1061 bufx = getpbuf(NULL); 1062 biox = &bufx->b_bio1; 1063 cluster_append(nbio, bufx); 1064 bufx->b_flags |= (bp->b_flags & B_ORDERED); 1065 bufx->b_cmd = bp->b_cmd; 1066 biox->bio_done = swap_chain_iodone; 1067 biox->bio_offset = (off_t)blk << PAGE_SHIFT; 1068 biox->bio_caller_info1.cluster_parent = nbio; 1069 biox_blkno = blk; 1070 bufx->b_bcount = 0; 1071 bufx->b_data = data; 1072 } 1073 bufx->b_bcount += PAGE_SIZE; 1074 } 1075 --count; 1076 ++start; 1077 data += PAGE_SIZE; 1078 } 1079 1080 vm_object_drop(object); 1081 1082 /* 1083 * Flush out last buffer 1084 */ 1085 if (biox) { 1086 if (bufx->b_cmd == BUF_CMD_READ) { 1087 ++mycpu->gd_cnt.v_swapin; 1088 mycpu->gd_cnt.v_swappgsin += btoc(bufx->b_bcount); 1089 } else { 1090 ++mycpu->gd_cnt.v_swapout; 1091 mycpu->gd_cnt.v_swappgsout += btoc(bufx->b_bcount); 1092 bufx->b_dirtyend = bufx->b_bcount; 1093 } 1094 KKASSERT(bufx->b_bcount); 1095 if (bufx->b_cmd != BUF_CMD_READ) 1096 bufx->b_dirtyend = bufx->b_bcount; 1097 /* biox, bufx = NULL */ 1098 } 1099 1100 /* 1101 * Now initiate all the I/O. Be careful looping on our chain as 1102 * I/O's may complete while we are still initiating them. 1103 * 1104 * If the request is a 100% sparse read no bios will be present 1105 * and we just biodone() the buffer. 1106 */ 1107 nbio->bio_caller_info2.cluster_tail = NULL; 1108 bufx = nbio->bio_caller_info1.cluster_head; 1109 1110 if (bufx) { 1111 while (bufx) { 1112 biox = &bufx->b_bio1; 1113 BUF_KERNPROC(bufx); 1114 bufx = bufx->b_cluster_next; 1115 vn_strategy(swapdev_vp, biox); 1116 } 1117 } else { 1118 biodone(bio); 1119 } 1120 1121 /* 1122 * Completion of the cluster will also call biodone_chain(nbio). 1123 * We never call biodone(nbio) so we don't have to worry about 1124 * setting up a bio_done callback. It's handled in the sub-IO. 1125 */ 1126 /**/ 1127 } 1128 1129 /* 1130 * biodone callback 1131 * 1132 * No requirements. 1133 */ 1134 static void 1135 swap_chain_iodone(struct bio *biox) 1136 { 1137 struct buf **nextp; 1138 struct buf *bufx; /* chained sub-buffer */ 1139 struct bio *nbio; /* parent nbio with chain glue */ 1140 struct buf *bp; /* original bp associated with nbio */ 1141 int chain_empty; 1142 1143 bufx = biox->bio_buf; 1144 nbio = biox->bio_caller_info1.cluster_parent; 1145 bp = nbio->bio_buf; 1146 1147 /* 1148 * Update the original buffer 1149 */ 1150 KKASSERT(bp != NULL); 1151 if (bufx->b_flags & B_ERROR) { 1152 atomic_set_int(&bufx->b_flags, B_ERROR); 1153 bp->b_error = bufx->b_error; /* race ok */ 1154 } else if (bufx->b_resid != 0) { 1155 atomic_set_int(&bufx->b_flags, B_ERROR); 1156 bp->b_error = EINVAL; /* race ok */ 1157 } else { 1158 atomic_subtract_int(&bp->b_resid, bufx->b_bcount); 1159 } 1160 1161 /* 1162 * Remove us from the chain. 1163 */ 1164 spin_lock(&swapbp_spin); 1165 nextp = &nbio->bio_caller_info1.cluster_head; 1166 while (*nextp != bufx) { 1167 KKASSERT(*nextp != NULL); 1168 nextp = &(*nextp)->b_cluster_next; 1169 } 1170 *nextp = bufx->b_cluster_next; 1171 chain_empty = (nbio->bio_caller_info1.cluster_head == NULL); 1172 spin_unlock(&swapbp_spin); 1173 1174 /* 1175 * Clean up bufx. If the chain is now empty we finish out 1176 * the parent. Note that we may be racing other completions 1177 * so we must use the chain_empty status from above. 1178 */ 1179 if (chain_empty) { 1180 if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) { 1181 atomic_set_int(&bp->b_flags, B_ERROR); 1182 bp->b_error = EINVAL; 1183 } 1184 biodone_chain(nbio); 1185 } 1186 relpbuf(bufx, NULL); 1187 } 1188 1189 /* 1190 * SWAP_PAGER_GETPAGES() - bring page in from swap 1191 * 1192 * The requested page may have to be brought in from swap. Calculate the 1193 * swap block and bring in additional pages if possible. All pages must 1194 * have contiguous swap block assignments and reside in the same object. 1195 * 1196 * The caller has a single vm_object_pip_add() reference prior to 1197 * calling us and we should return with the same. 1198 * 1199 * The caller has BUSY'd the page. We should return with (*mpp) left busy, 1200 * and any additinal pages unbusied. 1201 * 1202 * If the caller encounters a PG_RAM page it will pass it to us even though 1203 * it may be valid and dirty. We cannot overwrite the page in this case! 1204 * The case is used to allow us to issue pure read-aheads. 1205 * 1206 * NOTE! XXX This code does not entirely pipeline yet due to the fact that 1207 * the PG_RAM page is validated at the same time as mreq. What we 1208 * really need to do is issue a separate read-ahead pbuf. 1209 * 1210 * No requirements. 1211 */ 1212 static int 1213 swap_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess) 1214 { 1215 struct buf *bp; 1216 struct bio *bio; 1217 vm_page_t mreq; 1218 vm_page_t m; 1219 vm_offset_t kva; 1220 swblk_t blk; 1221 int i; 1222 int j; 1223 int raonly; 1224 int error; 1225 u_int32_t flags; 1226 vm_page_t marray[XIO_INTERNAL_PAGES]; 1227 1228 mreq = *mpp; 1229 1230 vm_object_hold(object); 1231 if (mreq->object != object) { 1232 panic("swap_pager_getpages: object mismatch %p/%p", 1233 object, 1234 mreq->object 1235 ); 1236 } 1237 1238 /* 1239 * We don't want to overwrite a fully valid page as it might be 1240 * dirty. This case can occur when e.g. vm_fault hits a perfectly 1241 * valid page with PG_RAM set. 1242 * 1243 * In this case we see if the next page is a suitable page-in 1244 * candidate and if it is we issue read-ahead. PG_RAM will be 1245 * set on the last page of the read-ahead to continue the pipeline. 1246 */ 1247 if (mreq->valid == VM_PAGE_BITS_ALL) { 1248 if (swap_burst_read == 0 || mreq->pindex + 1 >= object->size) { 1249 vm_object_drop(object); 1250 return(VM_PAGER_OK); 1251 } 1252 blk = swp_pager_meta_ctl(object, mreq->pindex + 1, 0); 1253 if (blk == SWAPBLK_NONE) { 1254 vm_object_drop(object); 1255 return(VM_PAGER_OK); 1256 } 1257 m = vm_page_lookup_busy_try(object, mreq->pindex + 1, 1258 TRUE, &error); 1259 if (error) { 1260 vm_object_drop(object); 1261 return(VM_PAGER_OK); 1262 } else if (m == NULL) { 1263 /* 1264 * Use VM_ALLOC_QUICK to avoid blocking on cache 1265 * page reuse. 1266 */ 1267 m = vm_page_alloc(object, mreq->pindex + 1, 1268 VM_ALLOC_QUICK); 1269 if (m == NULL) { 1270 vm_object_drop(object); 1271 return(VM_PAGER_OK); 1272 } 1273 } else { 1274 if (m->valid) { 1275 vm_page_wakeup(m); 1276 vm_object_drop(object); 1277 return(VM_PAGER_OK); 1278 } 1279 vm_page_unqueue_nowakeup(m); 1280 } 1281 /* page is busy */ 1282 mreq = m; 1283 raonly = 1; 1284 } else { 1285 raonly = 0; 1286 } 1287 1288 /* 1289 * Try to block-read contiguous pages from swap if sequential, 1290 * otherwise just read one page. Contiguous pages from swap must 1291 * reside within a single device stripe because the I/O cannot be 1292 * broken up across multiple stripes. 1293 * 1294 * Note that blk and iblk can be SWAPBLK_NONE but the loop is 1295 * set up such that the case(s) are handled implicitly. 1296 */ 1297 blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0); 1298 marray[0] = mreq; 1299 1300 for (i = 1; i <= swap_burst_read && 1301 i < XIO_INTERNAL_PAGES && 1302 mreq->pindex + i < object->size; ++i) { 1303 swblk_t iblk; 1304 1305 iblk = swp_pager_meta_ctl(object, mreq->pindex + i, 0); 1306 if (iblk != blk + i) 1307 break; 1308 if ((blk ^ iblk) & ~SWB_DMMASK) 1309 break; 1310 m = vm_page_lookup_busy_try(object, mreq->pindex + i, 1311 TRUE, &error); 1312 if (error) { 1313 break; 1314 } else if (m == NULL) { 1315 /* 1316 * Use VM_ALLOC_QUICK to avoid blocking on cache 1317 * page reuse. 1318 */ 1319 m = vm_page_alloc(object, mreq->pindex + i, 1320 VM_ALLOC_QUICK); 1321 if (m == NULL) 1322 break; 1323 } else { 1324 if (m->valid) { 1325 vm_page_wakeup(m); 1326 break; 1327 } 1328 vm_page_unqueue_nowakeup(m); 1329 } 1330 /* page is busy */ 1331 marray[i] = m; 1332 } 1333 if (i > 1) 1334 vm_page_flag_set(marray[i - 1], PG_RAM); 1335 1336 /* 1337 * If mreq is the requested page and we have nothing to do return 1338 * VM_PAGER_FAIL. If raonly is set mreq is just another read-ahead 1339 * page and must be cleaned up. 1340 */ 1341 if (blk == SWAPBLK_NONE) { 1342 KKASSERT(i == 1); 1343 if (raonly) { 1344 vnode_pager_freepage(mreq); 1345 vm_object_drop(object); 1346 return(VM_PAGER_OK); 1347 } else { 1348 vm_object_drop(object); 1349 return(VM_PAGER_FAIL); 1350 } 1351 } 1352 1353 /* 1354 * map our page(s) into kva for input 1355 */ 1356 bp = getpbuf_kva(&nsw_rcount); 1357 bio = &bp->b_bio1; 1358 kva = (vm_offset_t) bp->b_kvabase; 1359 bcopy(marray, bp->b_xio.xio_pages, i * sizeof(vm_page_t)); 1360 pmap_qenter(kva, bp->b_xio.xio_pages, i); 1361 1362 bp->b_data = (caddr_t)kva; 1363 bp->b_bcount = PAGE_SIZE * i; 1364 bp->b_xio.xio_npages = i; 1365 bio->bio_done = swp_pager_async_iodone; 1366 bio->bio_offset = (off_t)blk << PAGE_SHIFT; 1367 bio->bio_caller_info1.index = SWBIO_READ; 1368 1369 /* 1370 * Set index. If raonly set the index beyond the array so all 1371 * the pages are treated the same, otherwise the original mreq is 1372 * at index 0. 1373 */ 1374 if (raonly) 1375 bio->bio_driver_info = (void *)(intptr_t)i; 1376 else 1377 bio->bio_driver_info = (void *)(intptr_t)0; 1378 1379 for (j = 0; j < i; ++j) 1380 vm_page_flag_set(bp->b_xio.xio_pages[j], PG_SWAPINPROG); 1381 1382 mycpu->gd_cnt.v_swapin++; 1383 mycpu->gd_cnt.v_swappgsin += bp->b_xio.xio_npages; 1384 1385 /* 1386 * We still hold the lock on mreq, and our automatic completion routine 1387 * does not remove it. 1388 */ 1389 vm_object_pip_add(object, bp->b_xio.xio_npages); 1390 1391 /* 1392 * perform the I/O. NOTE!!! bp cannot be considered valid after 1393 * this point because we automatically release it on completion. 1394 * Instead, we look at the one page we are interested in which we 1395 * still hold a lock on even through the I/O completion. 1396 * 1397 * The other pages in our m[] array are also released on completion, 1398 * so we cannot assume they are valid anymore either. 1399 */ 1400 bp->b_cmd = BUF_CMD_READ; 1401 BUF_KERNPROC(bp); 1402 vn_strategy(swapdev_vp, bio); 1403 1404 /* 1405 * Wait for the page we want to complete. PG_SWAPINPROG is always 1406 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1407 * is set in the meta-data. 1408 * 1409 * If this is a read-ahead only we return immediately without 1410 * waiting for I/O. 1411 */ 1412 if (raonly) { 1413 vm_object_drop(object); 1414 return(VM_PAGER_OK); 1415 } 1416 1417 /* 1418 * Read-ahead includes originally requested page case. 1419 */ 1420 for (;;) { 1421 flags = mreq->flags; 1422 cpu_ccfence(); 1423 if ((flags & PG_SWAPINPROG) == 0) 1424 break; 1425 tsleep_interlock(mreq, 0); 1426 if (!atomic_cmpset_int(&mreq->flags, flags, 1427 flags | PG_WANTED | PG_REFERENCED)) { 1428 continue; 1429 } 1430 mycpu->gd_cnt.v_intrans++; 1431 if (tsleep(mreq, PINTERLOCKED, "swread", hz*20)) { 1432 kprintf( 1433 "swap_pager: indefinite wait buffer: " 1434 " bp %p offset: %lld, size: %ld\n", 1435 bp, 1436 (long long)bio->bio_offset, 1437 (long)bp->b_bcount 1438 ); 1439 } 1440 } 1441 1442 /* 1443 * mreq is left bussied after completion, but all the other pages 1444 * are freed. If we had an unrecoverable read error the page will 1445 * not be valid. 1446 */ 1447 vm_object_drop(object); 1448 if (mreq->valid != VM_PAGE_BITS_ALL) 1449 return(VM_PAGER_ERROR); 1450 else 1451 return(VM_PAGER_OK); 1452 1453 /* 1454 * A final note: in a low swap situation, we cannot deallocate swap 1455 * and mark a page dirty here because the caller is likely to mark 1456 * the page clean when we return, causing the page to possibly revert 1457 * to all-zero's later. 1458 */ 1459 } 1460 1461 /* 1462 * swap_pager_putpages: 1463 * 1464 * Assign swap (if necessary) and initiate I/O on the specified pages. 1465 * 1466 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1467 * are automatically converted to SWAP objects. 1468 * 1469 * In a low memory situation we may block in vn_strategy(), but the new 1470 * vm_page reservation system coupled with properly written VFS devices 1471 * should ensure that no low-memory deadlock occurs. This is an area 1472 * which needs work. 1473 * 1474 * The parent has N vm_object_pip_add() references prior to 1475 * calling us and will remove references for rtvals[] that are 1476 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1477 * completion. 1478 * 1479 * The parent has soft-busy'd the pages it passes us and will unbusy 1480 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1481 * We need to unbusy the rest on I/O completion. 1482 * 1483 * No requirements. 1484 */ 1485 void 1486 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1487 int flags, int *rtvals) 1488 { 1489 int i; 1490 int n = 0; 1491 1492 vm_object_hold(object); 1493 1494 if (count && m[0]->object != object) { 1495 panic("swap_pager_getpages: object mismatch %p/%p", 1496 object, 1497 m[0]->object 1498 ); 1499 } 1500 1501 /* 1502 * Step 1 1503 * 1504 * Turn object into OBJT_SWAP 1505 * Check for bogus sysops 1506 * 1507 * Force sync if not pageout process, we don't want any single 1508 * non-pageout process to be able to hog the I/O subsystem! This 1509 * can be overridden by setting. 1510 */ 1511 if (object->type == OBJT_DEFAULT) { 1512 if (object->type == OBJT_DEFAULT) 1513 swp_pager_meta_convert(object); 1514 } 1515 1516 /* 1517 * Normally we force synchronous swap I/O if this is not the 1518 * pageout daemon to prevent any single user process limited 1519 * via RLIMIT_RSS from hogging swap write bandwidth. 1520 */ 1521 if (curthread != pagethread && swap_user_async == 0) 1522 flags |= VM_PAGER_PUT_SYNC; 1523 1524 /* 1525 * Step 2 1526 * 1527 * Update nsw parameters from swap_async_max sysctl values. 1528 * Do not let the sysop crash the machine with bogus numbers. 1529 */ 1530 if (swap_async_max != nsw_wcount_async_max) { 1531 int n; 1532 1533 /* 1534 * limit range 1535 */ 1536 if ((n = swap_async_max) > nswbuf_kva / 2) 1537 n = nswbuf_kva / 2; 1538 if (n < 1) 1539 n = 1; 1540 swap_async_max = n; 1541 1542 /* 1543 * Adjust difference ( if possible ). If the current async 1544 * count is too low, we may not be able to make the adjustment 1545 * at this time. 1546 * 1547 * vm_token needed for nsw_wcount sleep interlock 1548 */ 1549 lwkt_gettoken(&vm_token); 1550 n -= nsw_wcount_async_max; 1551 if (nsw_wcount_async + n >= 0) { 1552 nsw_wcount_async_max += n; 1553 pbuf_adjcount(&nsw_wcount_async, n); 1554 } 1555 lwkt_reltoken(&vm_token); 1556 } 1557 1558 /* 1559 * Step 3 1560 * 1561 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1562 * The page is left dirty until the pageout operation completes 1563 * successfully. 1564 */ 1565 1566 for (i = 0; i < count; i += n) { 1567 struct buf *bp; 1568 struct bio *bio; 1569 swblk_t blk; 1570 int j; 1571 1572 /* 1573 * Maximum I/O size is limited by a number of factors. 1574 */ 1575 1576 n = min(BLIST_MAX_ALLOC, count - i); 1577 n = min(n, nsw_cluster_max); 1578 1579 lwkt_gettoken(&vm_token); 1580 1581 /* 1582 * Get biggest block of swap we can. If we fail, fall 1583 * back and try to allocate a smaller block. Don't go 1584 * overboard trying to allocate space if it would overly 1585 * fragment swap. 1586 */ 1587 while ( 1588 (blk = swp_pager_getswapspace(object, n)) == SWAPBLK_NONE && 1589 n > 4 1590 ) { 1591 n >>= 1; 1592 } 1593 if (blk == SWAPBLK_NONE) { 1594 for (j = 0; j < n; ++j) 1595 rtvals[i+j] = VM_PAGER_FAIL; 1596 lwkt_reltoken(&vm_token); 1597 continue; 1598 } 1599 if (vm_report_swap_allocs > 0) { 1600 kprintf("swap_alloc %08jx,%d\n", (intmax_t)blk, n); 1601 --vm_report_swap_allocs; 1602 } 1603 1604 /* 1605 * The I/O we are constructing cannot cross a physical 1606 * disk boundry in the swap stripe. 1607 */ 1608 if ((blk ^ (blk + n)) & ~SWB_DMMASK) { 1609 j = ((blk + SWB_DMMAX) & ~SWB_DMMASK) - blk; 1610 swp_pager_freeswapspace(object, blk + j, n - j); 1611 n = j; 1612 } 1613 1614 /* 1615 * All I/O parameters have been satisfied, build the I/O 1616 * request and assign the swap space. 1617 */ 1618 if ((flags & VM_PAGER_PUT_SYNC)) 1619 bp = getpbuf_kva(&nsw_wcount_sync); 1620 else 1621 bp = getpbuf_kva(&nsw_wcount_async); 1622 bio = &bp->b_bio1; 1623 1624 lwkt_reltoken(&vm_token); 1625 1626 pmap_qenter((vm_offset_t)bp->b_data, &m[i], n); 1627 1628 bp->b_bcount = PAGE_SIZE * n; 1629 bio->bio_offset = (off_t)blk << PAGE_SHIFT; 1630 1631 for (j = 0; j < n; ++j) { 1632 vm_page_t mreq = m[i+j]; 1633 1634 swp_pager_meta_build(mreq->object, mreq->pindex, 1635 blk + j); 1636 if (object->type == OBJT_SWAP) 1637 vm_page_dirty(mreq); 1638 rtvals[i+j] = VM_PAGER_OK; 1639 1640 vm_page_flag_set(mreq, PG_SWAPINPROG); 1641 bp->b_xio.xio_pages[j] = mreq; 1642 } 1643 bp->b_xio.xio_npages = n; 1644 1645 mycpu->gd_cnt.v_swapout++; 1646 mycpu->gd_cnt.v_swappgsout += bp->b_xio.xio_npages; 1647 1648 bp->b_dirtyoff = 0; /* req'd for NFS */ 1649 bp->b_dirtyend = bp->b_bcount; /* req'd for NFS */ 1650 bp->b_cmd = BUF_CMD_WRITE; 1651 bio->bio_caller_info1.index = SWBIO_WRITE; 1652 1653 /* 1654 * asynchronous 1655 */ 1656 if ((flags & VM_PAGER_PUT_SYNC) == 0) { 1657 bio->bio_done = swp_pager_async_iodone; 1658 BUF_KERNPROC(bp); 1659 vn_strategy(swapdev_vp, bio); 1660 1661 for (j = 0; j < n; ++j) 1662 rtvals[i+j] = VM_PAGER_PEND; 1663 continue; 1664 } 1665 1666 /* 1667 * Issue synchrnously. 1668 * 1669 * Wait for the sync I/O to complete, then update rtvals. 1670 * We just set the rtvals[] to VM_PAGER_PEND so we can call 1671 * our async completion routine at the end, thus avoiding a 1672 * double-free. 1673 */ 1674 bio->bio_caller_info1.index |= SWBIO_SYNC; 1675 if (flags & VM_PAGER_TRY_TO_CACHE) 1676 bio->bio_caller_info1.index |= SWBIO_TTC; 1677 bio->bio_done = biodone_sync; 1678 bio->bio_flags |= BIO_SYNC; 1679 vn_strategy(swapdev_vp, bio); 1680 biowait(bio, "swwrt"); 1681 1682 for (j = 0; j < n; ++j) 1683 rtvals[i+j] = VM_PAGER_PEND; 1684 1685 /* 1686 * Now that we are through with the bp, we can call the 1687 * normal async completion, which frees everything up. 1688 */ 1689 swp_pager_async_iodone(bio); 1690 } 1691 vm_object_drop(object); 1692 } 1693 1694 /* 1695 * No requirements. 1696 * 1697 * Recalculate the low and high-water marks. 1698 */ 1699 void 1700 swap_pager_newswap(void) 1701 { 1702 /* 1703 * NOTE: vm_swap_max cannot exceed 1 billion blocks, which is the 1704 * limitation imposed by the blist code. Remember that this 1705 * will be divided by NSWAP_MAX (4), so each swap device is 1706 * limited to around a terrabyte. 1707 */ 1708 if (vm_swap_max) { 1709 nswap_lowat = (int64_t)vm_swap_max * 4 / 100; /* 4% left */ 1710 nswap_hiwat = (int64_t)vm_swap_max * 6 / 100; /* 6% left */ 1711 kprintf("swap low/high-water marks set to %d/%d\n", 1712 nswap_lowat, nswap_hiwat); 1713 } else { 1714 nswap_lowat = 128; 1715 nswap_hiwat = 512; 1716 } 1717 swp_sizecheck(); 1718 } 1719 1720 /* 1721 * swp_pager_async_iodone: 1722 * 1723 * Completion routine for asynchronous reads and writes from/to swap. 1724 * Also called manually by synchronous code to finish up a bp. 1725 * 1726 * For READ operations, the pages are PG_BUSY'd. For WRITE operations, 1727 * the pages are vm_page_t->busy'd. For READ operations, we PG_BUSY 1728 * unbusy all pages except the 'main' request page. For WRITE 1729 * operations, we vm_page_t->busy'd unbusy all pages ( we can do this 1730 * because we marked them all VM_PAGER_PEND on return from putpages ). 1731 * 1732 * This routine may not block. 1733 * 1734 * No requirements. 1735 */ 1736 static void 1737 swp_pager_async_iodone(struct bio *bio) 1738 { 1739 struct buf *bp = bio->bio_buf; 1740 vm_object_t object = NULL; 1741 int i; 1742 int *nswptr; 1743 1744 /* 1745 * report error 1746 */ 1747 if (bp->b_flags & B_ERROR) { 1748 kprintf( 1749 "swap_pager: I/O error - %s failed; offset %lld," 1750 "size %ld, error %d\n", 1751 ((bio->bio_caller_info1.index & SWBIO_READ) ? 1752 "pagein" : "pageout"), 1753 (long long)bio->bio_offset, 1754 (long)bp->b_bcount, 1755 bp->b_error 1756 ); 1757 } 1758 1759 /* 1760 * set object. 1761 */ 1762 if (bp->b_xio.xio_npages) 1763 object = bp->b_xio.xio_pages[0]->object; 1764 1765 /* 1766 * remove the mapping for kernel virtual 1767 */ 1768 pmap_qremove((vm_offset_t)bp->b_data, bp->b_xio.xio_npages); 1769 1770 /* 1771 * cleanup pages. If an error occurs writing to swap, we are in 1772 * very serious trouble. If it happens to be a disk error, though, 1773 * we may be able to recover by reassigning the swap later on. So 1774 * in this case we remove the m->swapblk assignment for the page 1775 * but do not free it in the rlist. The errornous block(s) are thus 1776 * never reallocated as swap. Redirty the page and continue. 1777 */ 1778 for (i = 0; i < bp->b_xio.xio_npages; ++i) { 1779 vm_page_t m = bp->b_xio.xio_pages[i]; 1780 1781 if (bp->b_flags & B_ERROR) { 1782 /* 1783 * If an error occurs I'd love to throw the swapblk 1784 * away without freeing it back to swapspace, so it 1785 * can never be used again. But I can't from an 1786 * interrupt. 1787 */ 1788 1789 if (bio->bio_caller_info1.index & SWBIO_READ) { 1790 /* 1791 * When reading, reqpage needs to stay 1792 * locked for the parent, but all other 1793 * pages can be freed. We still want to 1794 * wakeup the parent waiting on the page, 1795 * though. ( also: pg_reqpage can be -1 and 1796 * not match anything ). 1797 * 1798 * We have to wake specifically requested pages 1799 * up too because we cleared PG_SWAPINPROG and 1800 * someone may be waiting for that. 1801 * 1802 * NOTE: for reads, m->dirty will probably 1803 * be overridden by the original caller of 1804 * getpages so don't play cute tricks here. 1805 * 1806 * NOTE: We can't actually free the page from 1807 * here, because this is an interrupt. It 1808 * is not legal to mess with object->memq 1809 * from an interrupt. Deactivate the page 1810 * instead. 1811 */ 1812 1813 m->valid = 0; 1814 vm_page_flag_clear(m, PG_SWAPINPROG); 1815 1816 /* 1817 * bio_driver_info holds the requested page 1818 * index. 1819 */ 1820 if (i != (int)(intptr_t)bio->bio_driver_info) { 1821 vm_page_deactivate(m); 1822 vm_page_wakeup(m); 1823 } else { 1824 vm_page_flash(m); 1825 } 1826 /* 1827 * If i == bp->b_pager.pg_reqpage, do not wake 1828 * the page up. The caller needs to. 1829 */ 1830 } else { 1831 /* 1832 * If a write error occurs remove the swap 1833 * assignment (note that PG_SWAPPED may or 1834 * may not be set depending on prior activity). 1835 * 1836 * Re-dirty OBJT_SWAP pages as there is no 1837 * other backing store, we can't throw the 1838 * page away. 1839 * 1840 * Non-OBJT_SWAP pages (aka swapcache) must 1841 * not be dirtied since they may not have 1842 * been dirty in the first place, and they 1843 * do have backing store (the vnode). 1844 */ 1845 vm_page_busy_wait(m, FALSE, "swadpg"); 1846 swp_pager_meta_ctl(m->object, m->pindex, 1847 SWM_FREE); 1848 vm_page_flag_clear(m, PG_SWAPPED); 1849 if (m->object->type == OBJT_SWAP) { 1850 vm_page_dirty(m); 1851 vm_page_activate(m); 1852 } 1853 vm_page_flag_clear(m, PG_SWAPINPROG); 1854 vm_page_io_finish(m); 1855 vm_page_wakeup(m); 1856 } 1857 } else if (bio->bio_caller_info1.index & SWBIO_READ) { 1858 /* 1859 * NOTE: for reads, m->dirty will probably be 1860 * overridden by the original caller of getpages so 1861 * we cannot set them in order to free the underlying 1862 * swap in a low-swap situation. I don't think we'd 1863 * want to do that anyway, but it was an optimization 1864 * that existed in the old swapper for a time before 1865 * it got ripped out due to precisely this problem. 1866 * 1867 * If not the requested page then deactivate it. 1868 * 1869 * Note that the requested page, reqpage, is left 1870 * busied, but we still have to wake it up. The 1871 * other pages are released (unbusied) by 1872 * vm_page_wakeup(). We do not set reqpage's 1873 * valid bits here, it is up to the caller. 1874 */ 1875 1876 /* 1877 * NOTE: can't call pmap_clear_modify(m) from an 1878 * interrupt thread, the pmap code may have to map 1879 * non-kernel pmaps and currently asserts the case. 1880 */ 1881 /*pmap_clear_modify(m);*/ 1882 m->valid = VM_PAGE_BITS_ALL; 1883 vm_page_undirty(m); 1884 vm_page_flag_clear(m, PG_SWAPINPROG); 1885 vm_page_flag_set(m, PG_SWAPPED); 1886 1887 /* 1888 * We have to wake specifically requested pages 1889 * up too because we cleared PG_SWAPINPROG and 1890 * could be waiting for it in getpages. However, 1891 * be sure to not unbusy getpages specifically 1892 * requested page - getpages expects it to be 1893 * left busy. 1894 * 1895 * bio_driver_info holds the requested page 1896 */ 1897 if (i != (int)(intptr_t)bio->bio_driver_info) { 1898 vm_page_deactivate(m); 1899 vm_page_wakeup(m); 1900 } else { 1901 vm_page_flash(m); 1902 } 1903 } else { 1904 /* 1905 * Mark the page clean but do not mess with the 1906 * pmap-layer's modified state. That state should 1907 * also be clear since the caller protected the 1908 * page VM_PROT_READ, but allow the case. 1909 * 1910 * We are in an interrupt, avoid pmap operations. 1911 * 1912 * If we have a severe page deficit, deactivate the 1913 * page. Do not try to cache it (which would also 1914 * involve a pmap op), because the page might still 1915 * be read-heavy. 1916 * 1917 * When using the swap to cache clean vnode pages 1918 * we do not mess with the page dirty bits. 1919 */ 1920 vm_page_busy_wait(m, FALSE, "swadpg"); 1921 if (m->object->type == OBJT_SWAP) 1922 vm_page_undirty(m); 1923 vm_page_flag_clear(m, PG_SWAPINPROG); 1924 vm_page_flag_set(m, PG_SWAPPED); 1925 if (vm_page_count_severe()) 1926 vm_page_deactivate(m); 1927 vm_page_io_finish(m); 1928 if (bio->bio_caller_info1.index & SWBIO_TTC) 1929 vm_page_try_to_cache(m); 1930 else 1931 vm_page_wakeup(m); 1932 } 1933 } 1934 1935 /* 1936 * adjust pip. NOTE: the original parent may still have its own 1937 * pip refs on the object. 1938 */ 1939 1940 if (object) 1941 vm_object_pip_wakeup_n(object, bp->b_xio.xio_npages); 1942 1943 /* 1944 * Release the physical I/O buffer. 1945 * 1946 * NOTE: Due to synchronous operations in the write case b_cmd may 1947 * already be set to BUF_CMD_DONE and BIO_SYNC may have already 1948 * been cleared. 1949 * 1950 * Use vm_token to interlock nsw_rcount/wcount wakeup? 1951 */ 1952 lwkt_gettoken(&vm_token); 1953 if (bio->bio_caller_info1.index & SWBIO_READ) 1954 nswptr = &nsw_rcount; 1955 else if (bio->bio_caller_info1.index & SWBIO_SYNC) 1956 nswptr = &nsw_wcount_sync; 1957 else 1958 nswptr = &nsw_wcount_async; 1959 bp->b_cmd = BUF_CMD_DONE; 1960 relpbuf(bp, nswptr); 1961 lwkt_reltoken(&vm_token); 1962 } 1963 1964 /* 1965 * Fault-in a potentially swapped page and remove the swap reference. 1966 * (used by swapoff code) 1967 * 1968 * object must be held. 1969 */ 1970 static __inline void 1971 swp_pager_fault_page(vm_object_t object, int *sharedp, vm_pindex_t pindex) 1972 { 1973 struct vnode *vp; 1974 vm_page_t m; 1975 int error; 1976 1977 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 1978 1979 if (object->type == OBJT_VNODE) { 1980 /* 1981 * Any swap related to a vnode is due to swapcache. We must 1982 * vget() the vnode in case it is not active (otherwise 1983 * vref() will panic). Calling vm_object_page_remove() will 1984 * ensure that any swap ref is removed interlocked with the 1985 * page. clean_only is set to TRUE so we don't throw away 1986 * dirty pages. 1987 */ 1988 vp = object->handle; 1989 error = vget(vp, LK_SHARED | LK_RETRY | LK_CANRECURSE); 1990 if (error == 0) { 1991 vm_object_page_remove(object, pindex, pindex + 1, TRUE); 1992 vput(vp); 1993 } 1994 } else { 1995 /* 1996 * Otherwise it is a normal OBJT_SWAP object and we can 1997 * fault the page in and remove the swap. 1998 */ 1999 m = vm_fault_object_page(object, IDX_TO_OFF(pindex), 2000 VM_PROT_NONE, 2001 VM_FAULT_DIRTY | VM_FAULT_UNSWAP, 2002 sharedp, &error); 2003 if (m) 2004 vm_page_unhold(m); 2005 } 2006 } 2007 2008 /* 2009 * This removes all swap blocks related to a particular device. We have 2010 * to be careful of ripups during the scan. 2011 */ 2012 static int swp_pager_swapoff_callback(struct swblock *swap, void *data); 2013 2014 int 2015 swap_pager_swapoff(int devidx) 2016 { 2017 struct swswapoffinfo info; 2018 struct vm_object marker; 2019 vm_object_t object; 2020 int n; 2021 2022 bzero(&marker, sizeof(marker)); 2023 marker.type = OBJT_MARKER; 2024 2025 for (n = 0; n < VMOBJ_HSIZE; ++n) { 2026 lwkt_gettoken(&vmobj_tokens[n]); 2027 TAILQ_INSERT_HEAD(&vm_object_lists[n], &marker, object_list); 2028 2029 while ((object = TAILQ_NEXT(&marker, object_list)) != NULL) { 2030 if (object->type == OBJT_MARKER) 2031 goto skip; 2032 if (object->type != OBJT_SWAP && 2033 object->type != OBJT_VNODE) 2034 goto skip; 2035 vm_object_hold(object); 2036 if (object->type != OBJT_SWAP && 2037 object->type != OBJT_VNODE) { 2038 vm_object_drop(object); 2039 goto skip; 2040 } 2041 info.object = object; 2042 info.shared = 0; 2043 info.devidx = devidx; 2044 swblock_rb_tree_RB_SCAN(&object->swblock_root, 2045 NULL, swp_pager_swapoff_callback, 2046 &info); 2047 vm_object_drop(object); 2048 skip: 2049 if (object == TAILQ_NEXT(&marker, object_list)) { 2050 TAILQ_REMOVE(&vm_object_lists[n], 2051 &marker, object_list); 2052 TAILQ_INSERT_AFTER(&vm_object_lists[n], object, 2053 &marker, object_list); 2054 } 2055 } 2056 TAILQ_REMOVE(&vm_object_lists[n], &marker, object_list); 2057 lwkt_reltoken(&vmobj_tokens[n]); 2058 } 2059 2060 /* 2061 * If we fail to locate all swblocks we just fail gracefully and 2062 * do not bother to restore paging on the swap device. If the 2063 * user wants to retry the user can retry. 2064 */ 2065 if (swdevt[devidx].sw_nused) 2066 return (1); 2067 else 2068 return (0); 2069 } 2070 2071 static 2072 int 2073 swp_pager_swapoff_callback(struct swblock *swap, void *data) 2074 { 2075 struct swswapoffinfo *info = data; 2076 vm_object_t object = info->object; 2077 vm_pindex_t index; 2078 swblk_t v; 2079 int i; 2080 2081 index = swap->swb_index; 2082 for (i = 0; i < SWAP_META_PAGES; ++i) { 2083 /* 2084 * Make sure we don't race a dying object. This will 2085 * kill the scan of the object's swap blocks entirely. 2086 */ 2087 if (object->flags & OBJ_DEAD) 2088 return(-1); 2089 2090 /* 2091 * Fault the page, which can obviously block. If the swap 2092 * structure disappears break out. 2093 */ 2094 v = swap->swb_pages[i]; 2095 if (v != SWAPBLK_NONE && BLK2DEVIDX(v) == info->devidx) { 2096 swp_pager_fault_page(object, &info->shared, 2097 swap->swb_index + i); 2098 /* swap ptr might go away */ 2099 if (RB_LOOKUP(swblock_rb_tree, 2100 &object->swblock_root, index) != swap) { 2101 break; 2102 } 2103 } 2104 } 2105 return(0); 2106 } 2107 2108 /************************************************************************ 2109 * SWAP META DATA * 2110 ************************************************************************ 2111 * 2112 * These routines manipulate the swap metadata stored in the 2113 * OBJT_SWAP object. 2114 * 2115 * Swap metadata is implemented with a global hash and not directly 2116 * linked into the object. Instead the object simply contains 2117 * appropriate tracking counters. 2118 */ 2119 2120 /* 2121 * Lookup the swblock containing the specified swap block index. 2122 * 2123 * The caller must hold the object. 2124 */ 2125 static __inline 2126 struct swblock * 2127 swp_pager_lookup(vm_object_t object, vm_pindex_t index) 2128 { 2129 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 2130 index &= ~(vm_pindex_t)SWAP_META_MASK; 2131 return (RB_LOOKUP(swblock_rb_tree, &object->swblock_root, index)); 2132 } 2133 2134 /* 2135 * Remove a swblock from the RB tree. 2136 * 2137 * The caller must hold the object. 2138 */ 2139 static __inline 2140 void 2141 swp_pager_remove(vm_object_t object, struct swblock *swap) 2142 { 2143 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 2144 RB_REMOVE(swblock_rb_tree, &object->swblock_root, swap); 2145 } 2146 2147 /* 2148 * Convert default object to swap object if necessary 2149 * 2150 * The caller must hold the object. 2151 */ 2152 static void 2153 swp_pager_meta_convert(vm_object_t object) 2154 { 2155 if (object->type == OBJT_DEFAULT) { 2156 object->type = OBJT_SWAP; 2157 KKASSERT(object->swblock_count == 0); 2158 } 2159 } 2160 2161 /* 2162 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 2163 * 2164 * We first convert the object to a swap object if it is a default 2165 * object. Vnode objects do not need to be converted. 2166 * 2167 * The specified swapblk is added to the object's swap metadata. If 2168 * the swapblk is not valid, it is freed instead. Any previously 2169 * assigned swapblk is freed. 2170 * 2171 * The caller must hold the object. 2172 */ 2173 static void 2174 swp_pager_meta_build(vm_object_t object, vm_pindex_t index, swblk_t swapblk) 2175 { 2176 struct swblock *swap; 2177 struct swblock *oswap; 2178 vm_pindex_t v; 2179 2180 KKASSERT(swapblk != SWAPBLK_NONE); 2181 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 2182 2183 /* 2184 * Convert object if necessary 2185 */ 2186 if (object->type == OBJT_DEFAULT) 2187 swp_pager_meta_convert(object); 2188 2189 /* 2190 * Locate swblock. If not found create, but if we aren't adding 2191 * anything just return. If we run out of space in the map we wait 2192 * and, since the hash table may have changed, retry. 2193 */ 2194 retry: 2195 swap = swp_pager_lookup(object, index); 2196 2197 if (swap == NULL) { 2198 int i; 2199 2200 swap = zalloc(swap_zone); 2201 if (swap == NULL) { 2202 vm_wait(0); 2203 goto retry; 2204 } 2205 swap->swb_index = index & ~(vm_pindex_t)SWAP_META_MASK; 2206 swap->swb_count = 0; 2207 2208 ++object->swblock_count; 2209 2210 for (i = 0; i < SWAP_META_PAGES; ++i) 2211 swap->swb_pages[i] = SWAPBLK_NONE; 2212 oswap = RB_INSERT(swblock_rb_tree, &object->swblock_root, swap); 2213 KKASSERT(oswap == NULL); 2214 } 2215 2216 /* 2217 * Delete prior contents of metadata. 2218 * 2219 * NOTE: Decrement swb_count after the freeing operation (which 2220 * might block) to prevent racing destruction of the swblock. 2221 */ 2222 index &= SWAP_META_MASK; 2223 2224 while ((v = swap->swb_pages[index]) != SWAPBLK_NONE) { 2225 swap->swb_pages[index] = SWAPBLK_NONE; 2226 /* can block */ 2227 swp_pager_freeswapspace(object, v, 1); 2228 --swap->swb_count; 2229 --mycpu->gd_vmtotal.t_vm; 2230 } 2231 2232 /* 2233 * Enter block into metadata 2234 */ 2235 swap->swb_pages[index] = swapblk; 2236 if (swapblk != SWAPBLK_NONE) { 2237 ++swap->swb_count; 2238 ++mycpu->gd_vmtotal.t_vm; 2239 } 2240 } 2241 2242 /* 2243 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2244 * 2245 * The requested range of blocks is freed, with any associated swap 2246 * returned to the swap bitmap. 2247 * 2248 * This routine will free swap metadata structures as they are cleaned 2249 * out. This routine does *NOT* operate on swap metadata associated 2250 * with resident pages. 2251 * 2252 * The caller must hold the object. 2253 */ 2254 static int swp_pager_meta_free_callback(struct swblock *swb, void *data); 2255 2256 static void 2257 swp_pager_meta_free(vm_object_t object, vm_pindex_t index, vm_pindex_t count) 2258 { 2259 struct swfreeinfo info; 2260 2261 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 2262 2263 /* 2264 * Nothing to do 2265 */ 2266 if (object->swblock_count == 0) { 2267 KKASSERT(RB_EMPTY(&object->swblock_root)); 2268 return; 2269 } 2270 if (count == 0) 2271 return; 2272 2273 /* 2274 * Setup for RB tree scan. Note that the pindex range can be huge 2275 * due to the 64 bit page index space so we cannot safely iterate. 2276 */ 2277 info.object = object; 2278 info.basei = index & ~(vm_pindex_t)SWAP_META_MASK; 2279 info.begi = index; 2280 info.endi = index + count - 1; 2281 swblock_rb_tree_RB_SCAN(&object->swblock_root, rb_swblock_scancmp, 2282 swp_pager_meta_free_callback, &info); 2283 } 2284 2285 /* 2286 * The caller must hold the object. 2287 */ 2288 static 2289 int 2290 swp_pager_meta_free_callback(struct swblock *swap, void *data) 2291 { 2292 struct swfreeinfo *info = data; 2293 vm_object_t object = info->object; 2294 int index; 2295 int eindex; 2296 2297 /* 2298 * Figure out the range within the swblock. The wider scan may 2299 * return edge-case swap blocks when the start and/or end points 2300 * are in the middle of a block. 2301 */ 2302 if (swap->swb_index < info->begi) 2303 index = (int)info->begi & SWAP_META_MASK; 2304 else 2305 index = 0; 2306 2307 if (swap->swb_index + SWAP_META_PAGES > info->endi) 2308 eindex = (int)info->endi & SWAP_META_MASK; 2309 else 2310 eindex = SWAP_META_MASK; 2311 2312 /* 2313 * Scan and free the blocks. The loop terminates early 2314 * if (swap) runs out of blocks and could be freed. 2315 * 2316 * NOTE: Decrement swb_count after swp_pager_freeswapspace() 2317 * to deal with a zfree race. 2318 */ 2319 while (index <= eindex) { 2320 swblk_t v = swap->swb_pages[index]; 2321 2322 if (v != SWAPBLK_NONE) { 2323 swap->swb_pages[index] = SWAPBLK_NONE; 2324 /* can block */ 2325 swp_pager_freeswapspace(object, v, 1); 2326 --mycpu->gd_vmtotal.t_vm; 2327 if (--swap->swb_count == 0) { 2328 swp_pager_remove(object, swap); 2329 zfree(swap_zone, swap); 2330 --object->swblock_count; 2331 break; 2332 } 2333 } 2334 ++index; 2335 } 2336 2337 /* swap may be invalid here due to zfree above */ 2338 lwkt_yield(); 2339 2340 return(0); 2341 } 2342 2343 /* 2344 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2345 * 2346 * This routine locates and destroys all swap metadata associated with 2347 * an object. 2348 * 2349 * NOTE: Decrement swb_count after the freeing operation (which 2350 * might block) to prevent racing destruction of the swblock. 2351 * 2352 * The caller must hold the object. 2353 */ 2354 static void 2355 swp_pager_meta_free_all(vm_object_t object) 2356 { 2357 struct swblock *swap; 2358 int i; 2359 2360 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 2361 2362 while ((swap = RB_ROOT(&object->swblock_root)) != NULL) { 2363 swp_pager_remove(object, swap); 2364 for (i = 0; i < SWAP_META_PAGES; ++i) { 2365 swblk_t v = swap->swb_pages[i]; 2366 if (v != SWAPBLK_NONE) { 2367 /* can block */ 2368 swp_pager_freeswapspace(object, v, 1); 2369 --swap->swb_count; 2370 --mycpu->gd_vmtotal.t_vm; 2371 } 2372 } 2373 if (swap->swb_count != 0) 2374 panic("swap_pager_meta_free_all: swb_count != 0"); 2375 zfree(swap_zone, swap); 2376 --object->swblock_count; 2377 lwkt_yield(); 2378 } 2379 KKASSERT(object->swblock_count == 0); 2380 } 2381 2382 /* 2383 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. 2384 * 2385 * This routine is capable of looking up, popping, or freeing 2386 * swapblk assignments in the swap meta data or in the vm_page_t. 2387 * The routine typically returns the swapblk being looked-up, or popped, 2388 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block 2389 * was invalid. This routine will automatically free any invalid 2390 * meta-data swapblks. 2391 * 2392 * It is not possible to store invalid swapblks in the swap meta data 2393 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking. 2394 * 2395 * When acting on a busy resident page and paging is in progress, we 2396 * have to wait until paging is complete but otherwise can act on the 2397 * busy page. 2398 * 2399 * SWM_FREE remove and free swap block from metadata 2400 * SWM_POP remove from meta data but do not free.. pop it out 2401 * 2402 * The caller must hold the object. 2403 */ 2404 static swblk_t 2405 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t index, int flags) 2406 { 2407 struct swblock *swap; 2408 swblk_t r1; 2409 2410 if (object->swblock_count == 0) 2411 return(SWAPBLK_NONE); 2412 2413 r1 = SWAPBLK_NONE; 2414 swap = swp_pager_lookup(object, index); 2415 2416 if (swap != NULL) { 2417 index &= SWAP_META_MASK; 2418 r1 = swap->swb_pages[index]; 2419 2420 if (r1 != SWAPBLK_NONE) { 2421 if (flags & (SWM_FREE|SWM_POP)) { 2422 swap->swb_pages[index] = SWAPBLK_NONE; 2423 --mycpu->gd_vmtotal.t_vm; 2424 if (--swap->swb_count == 0) { 2425 swp_pager_remove(object, swap); 2426 zfree(swap_zone, swap); 2427 --object->swblock_count; 2428 } 2429 } 2430 /* swap ptr may be invalid */ 2431 if (flags & SWM_FREE) { 2432 swp_pager_freeswapspace(object, r1, 1); 2433 r1 = SWAPBLK_NONE; 2434 } 2435 } 2436 /* swap ptr may be invalid */ 2437 } 2438 return(r1); 2439 } 2440