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