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