1 /* 2 * (MPSAFE) 3 * 4 * Copyright (c) 1998-2010 The DragonFly Project. All rights reserved. 5 * 6 * This code is derived from software contributed to The DragonFly Project 7 * by Matthew Dillon <dillon@backplane.com> 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in 17 * the documentation and/or other materials provided with the 18 * distribution. 19 * 3. Neither the name of The DragonFly Project nor the names of its 20 * contributors may be used to endorse or promote products derived 21 * from this software without specific, prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 24 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 26 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 27 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 28 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 29 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 30 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 31 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 32 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 33 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * Copyright (c) 1994 John S. Dyson 37 * Copyright (c) 1990 University of Utah. 38 * Copyright (c) 1991, 1993 39 * The Regents of the University of California. All rights reserved. 40 * 41 * This code is derived from software contributed to Berkeley by 42 * the Systems Programming Group of the University of Utah Computer 43 * Science Department. 44 * 45 * Redistribution and use in source and binary forms, with or without 46 * modification, are permitted provided that the following conditions 47 * are met: 48 * 1. Redistributions of source code must retain the above copyright 49 * notice, this list of conditions and the following disclaimer. 50 * 2. Redistributions in binary form must reproduce the above copyright 51 * notice, this list of conditions and the following disclaimer in the 52 * documentation and/or other materials provided with the distribution. 53 * 3. Neither the name of the University nor the names of its contributors 54 * may be used to endorse or promote products derived from this software 55 * without specific prior written permission. 56 * 57 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 58 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 59 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 60 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 61 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 62 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 63 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 64 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 65 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 66 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 67 * SUCH DAMAGE. 68 * 69 * New Swap System 70 * Matthew Dillon 71 * 72 * Radix Bitmap 'blists'. 73 * 74 * - The new swapper uses the new radix bitmap code. This should scale 75 * to arbitrarily small or arbitrarily large swap spaces and an almost 76 * arbitrary degree of fragmentation. 77 * 78 * Features: 79 * 80 * - on the fly reallocation of swap during putpages. The new system 81 * does not try to keep previously allocated swap blocks for dirty 82 * pages. 83 * 84 * - on the fly deallocation of swap 85 * 86 * - No more garbage collection required. Unnecessarily allocated swap 87 * blocks only exist for dirty vm_page_t's now and these are already 88 * cycled (in a high-load system) by the pager. We also do on-the-fly 89 * removal of invalidated swap blocks when a page is destroyed 90 * or renamed. 91 * 92 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$ 93 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94 94 * $FreeBSD: src/sys/vm/swap_pager.c,v 1.130.2.12 2002/08/31 21:15:55 dillon Exp $ 95 */ 96 97 #include "opt_swap.h" 98 #include <sys/param.h> 99 #include <sys/systm.h> 100 #include <sys/conf.h> 101 #include <sys/kernel.h> 102 #include <sys/proc.h> 103 #include <sys/buf.h> 104 #include <sys/vnode.h> 105 #include <sys/malloc.h> 106 #include <sys/vmmeter.h> 107 #include <sys/sysctl.h> 108 #include <sys/blist.h> 109 #include <sys/lock.h> 110 #include <sys/kcollect.h> 111 112 #include <vm/vm.h> 113 #include <vm/vm_object.h> 114 #include <vm/vm_page.h> 115 #include <vm/vm_pager.h> 116 #include <vm/vm_pageout.h> 117 #include <vm/swap_pager.h> 118 #include <vm/vm_extern.h> 119 #include <vm/vm_zone.h> 120 #include <vm/vnode_pager.h> 121 122 #include <sys/buf2.h> 123 #include <vm/vm_page2.h> 124 125 #ifndef MAX_PAGEOUT_CLUSTER 126 #define MAX_PAGEOUT_CLUSTER SWB_NPAGES 127 #endif 128 129 #define SWM_FREE 0x02 /* free, period */ 130 #define SWM_POP 0x04 /* pop out */ 131 132 #define SWBIO_READ 0x01 133 #define SWBIO_WRITE 0x02 134 #define SWBIO_SYNC 0x04 135 #define SWBIO_TTC 0x08 /* for OBJPC_TRY_TO_CACHE */ 136 137 struct swfreeinfo { 138 vm_object_t object; 139 vm_pindex_t basei; 140 vm_pindex_t begi; 141 vm_pindex_t endi; /* inclusive */ 142 }; 143 144 struct swswapoffinfo { 145 vm_object_t object; 146 int devidx; 147 int shared; 148 }; 149 150 /* 151 * vm_swap_size is in page-sized chunks now. It was DEV_BSIZE'd chunks 152 * in the old system. 153 */ 154 155 int swap_pager_full; /* swap space exhaustion (task killing) */ 156 int swap_fail_ticks; /* when we became exhausted */ 157 int swap_pager_almost_full; /* swap space exhaustion (w/ hysteresis)*/ 158 swblk_t vm_swap_cache_use; 159 swblk_t vm_swap_anon_use; 160 static int vm_report_swap_allocs; 161 162 static struct krate kswaprate = { 1 }; 163 static int nsw_rcount; /* free read buffers */ 164 static int nsw_wcount_sync; /* limit write buffers / synchronous */ 165 static int nsw_wcount_async; /* limit write buffers / asynchronous */ 166 static int nsw_wcount_async_max;/* assigned maximum */ 167 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 168 169 struct blist *swapblist; 170 static int swap_async_max = 4; /* maximum in-progress async I/O's */ 171 static int swap_burst_read = 0; /* allow burst reading */ 172 static swblk_t swapiterator; /* linearize allocations */ 173 int swap_user_async = 0; /* user swap pager operation can be async */ 174 175 static struct spinlock swapbp_spin = SPINLOCK_INITIALIZER(&swapbp_spin, "swapbp_spin"); 176 177 /* from vm_swap.c */ 178 extern struct vnode *swapdev_vp; 179 extern struct swdevt *swdevt; 180 extern int nswdev; 181 182 #define BLK2DEVIDX(blk) (nswdev > 1 ? blk / SWB_DMMAX % nswdev : 0) 183 184 SYSCTL_INT(_vm, OID_AUTO, swap_async_max, 185 CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops"); 186 SYSCTL_INT(_vm, OID_AUTO, swap_burst_read, 187 CTLFLAG_RW, &swap_burst_read, 0, "Allow burst reads for pageins"); 188 SYSCTL_INT(_vm, OID_AUTO, swap_user_async, 189 CTLFLAG_RW, &swap_user_async, 0, "Allow async uuser swap write I/O"); 190 191 #if SWBLK_BITS == 64 192 SYSCTL_LONG(_vm, OID_AUTO, swap_cache_use, 193 CTLFLAG_RD, &vm_swap_cache_use, 0, ""); 194 SYSCTL_LONG(_vm, OID_AUTO, swap_anon_use, 195 CTLFLAG_RD, &vm_swap_anon_use, 0, ""); 196 SYSCTL_LONG(_vm, OID_AUTO, swap_free, 197 CTLFLAG_RD, &vm_swap_size, 0, ""); 198 SYSCTL_LONG(_vm, OID_AUTO, swap_size, 199 CTLFLAG_RD, &vm_swap_max, 0, ""); 200 #else 201 SYSCTL_INT(_vm, OID_AUTO, swap_cache_use, 202 CTLFLAG_RD, &vm_swap_cache_use, 0, ""); 203 SYSCTL_INT(_vm, OID_AUTO, swap_anon_use, 204 CTLFLAG_RD, &vm_swap_anon_use, 0, ""); 205 SYSCTL_INT(_vm, OID_AUTO, swap_free, 206 CTLFLAG_RD, &vm_swap_size, 0, ""); 207 SYSCTL_INT(_vm, OID_AUTO, swap_size, 208 CTLFLAG_RD, &vm_swap_max, 0, ""); 209 #endif 210 SYSCTL_INT(_vm, OID_AUTO, report_swap_allocs, 211 CTLFLAG_RW, &vm_report_swap_allocs, 0, ""); 212 213 __read_mostly vm_zone_t swap_zone; 214 215 /* 216 * Red-Black tree for swblock entries 217 * 218 * The caller must hold vm_token 219 */ 220 RB_GENERATE2(swblock_rb_tree, swblock, swb_entry, rb_swblock_compare, 221 vm_pindex_t, swb_index); 222 223 int 224 rb_swblock_compare(struct swblock *swb1, struct swblock *swb2) 225 { 226 if (swb1->swb_index < swb2->swb_index) 227 return(-1); 228 if (swb1->swb_index > swb2->swb_index) 229 return(1); 230 return(0); 231 } 232 233 static 234 int 235 rb_swblock_scancmp(struct swblock *swb, void *data) 236 { 237 struct swfreeinfo *info = data; 238 239 if (swb->swb_index < info->basei) 240 return(-1); 241 if (swb->swb_index > info->endi) 242 return(1); 243 return(0); 244 } 245 246 static 247 int 248 rb_swblock_condcmp(struct swblock *swb, void *data) 249 { 250 struct swfreeinfo *info = data; 251 252 if (swb->swb_index < info->basei) 253 return(-1); 254 return(0); 255 } 256 257 /* 258 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 259 * calls hooked from other parts of the VM system and do not appear here. 260 * (see vm/swap_pager.h). 261 */ 262 263 static void swap_pager_dealloc (vm_object_t object); 264 static int swap_pager_getpage (vm_object_t, vm_page_t *, int); 265 static void swap_chain_iodone(struct bio *biox); 266 267 struct pagerops swappagerops = { 268 swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 269 swap_pager_getpage, /* pagein */ 270 swap_pager_putpages, /* pageout */ 271 swap_pager_haspage /* get backing store status for page */ 272 }; 273 274 /* 275 * SWB_DMMAX is in page-sized chunks with the new swap system. It was 276 * dev-bsized chunks in the old. SWB_DMMAX is always a power of 2. 277 * 278 * swap_*() routines are externally accessible. swp_*() routines are 279 * internal. 280 */ 281 282 int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 283 int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 284 285 static __inline void swp_sizecheck (void); 286 static void swp_pager_async_iodone (struct bio *bio); 287 288 /* 289 * Swap bitmap functions 290 */ 291 292 static __inline void swp_pager_freeswapspace(vm_object_t object, 293 swblk_t blk, int npages); 294 static __inline swblk_t swp_pager_getswapspace(vm_object_t object, int npages); 295 296 /* 297 * Metadata functions 298 */ 299 300 static void swp_pager_meta_convert(vm_object_t); 301 static void swp_pager_meta_build(vm_object_t, vm_pindex_t, swblk_t); 302 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 303 static void swp_pager_meta_free_all(vm_object_t); 304 static swblk_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 305 306 /* 307 * SWP_SIZECHECK() - update swap_pager_full indication 308 * 309 * update the swap_pager_almost_full indication and warn when we are 310 * about to run out of swap space, using lowat/hiwat hysteresis. 311 * 312 * Clear swap_pager_full ( task killing ) indication when lowat is met. 313 * 314 * No restrictions on call 315 * This routine may not block. 316 * SMP races are ok. 317 */ 318 static __inline void 319 swp_sizecheck(void) 320 { 321 if (vm_swap_size < nswap_lowat) { 322 if (swap_pager_almost_full == 0) { 323 kprintf("swap_pager: out of swap space\n"); 324 swap_pager_almost_full = 1; 325 swap_fail_ticks = ticks; 326 } 327 } else { 328 swap_pager_full = 0; 329 if (vm_swap_size > nswap_hiwat) 330 swap_pager_almost_full = 0; 331 } 332 } 333 334 /* 335 * Long-term data collection on 10-second interval. Return the value 336 * for KCOLLECT_SWAPPCT and set the values for SWAPANO and SWAPCCAC. 337 * 338 * Return total swap in the scale field. This can change if swap is 339 * regularly added or removed and may cause some historical confusion 340 * in that case, but SWAPPCT will always be historically accurate. 341 */ 342 343 #define PTOB(value) ((uint64_t)(value) << PAGE_SHIFT) 344 345 static uint64_t 346 collect_swap_callback(int n) 347 { 348 uint64_t total = vm_swap_max; 349 uint64_t anon = vm_swap_anon_use; 350 uint64_t cache = vm_swap_cache_use; 351 352 if (total == 0) /* avoid divide by zero */ 353 total = 1; 354 kcollect_setvalue(KCOLLECT_SWAPANO, PTOB(anon)); 355 kcollect_setvalue(KCOLLECT_SWAPCAC, PTOB(cache)); 356 kcollect_setscale(KCOLLECT_SWAPANO, 357 KCOLLECT_SCALE(KCOLLECT_SWAPANO_FORMAT, PTOB(total))); 358 kcollect_setscale(KCOLLECT_SWAPCAC, 359 KCOLLECT_SCALE(KCOLLECT_SWAPCAC_FORMAT, PTOB(total))); 360 return (((anon + cache) * 10000 + (total >> 1)) / total); 361 } 362 363 /* 364 * SWAP_PAGER_INIT() - initialize the swap pager! 365 * 366 * Expected to be started from system init. NOTE: This code is run 367 * before much else so be careful what you depend on. Most of the VM 368 * system has yet to be initialized at this point. 369 * 370 * Called from the low level boot code only. 371 */ 372 static void 373 swap_pager_init(void *arg __unused) 374 { 375 kcollect_register(KCOLLECT_SWAPPCT, "swapuse", collect_swap_callback, 376 KCOLLECT_SCALE(KCOLLECT_SWAPPCT_FORMAT, 0)); 377 kcollect_register(KCOLLECT_SWAPANO, "swapano", NULL, 378 KCOLLECT_SCALE(KCOLLECT_SWAPANO_FORMAT, 0)); 379 kcollect_register(KCOLLECT_SWAPCAC, "swapcac", NULL, 380 KCOLLECT_SCALE(KCOLLECT_SWAPCAC_FORMAT, 0)); 381 } 382 SYSINIT(vm_mem, SI_BOOT1_VM, SI_ORDER_THIRD, swap_pager_init, NULL); 383 384 /* 385 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 386 * 387 * Expected to be started from pageout process once, prior to entering 388 * its main loop. 389 * 390 * Called from the low level boot code only. 391 */ 392 void 393 swap_pager_swap_init(void) 394 { 395 int n, n2; 396 397 /* 398 * Number of in-transit swap bp operations. Don't 399 * exhaust the pbufs completely. Make sure we 400 * initialize workable values (0 will work for hysteresis 401 * but it isn't very efficient). 402 * 403 * The nsw_cluster_max is constrained by the number of pages an XIO 404 * holds, i.e., (MAXPHYS/PAGE_SIZE) and our locally defined 405 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 406 * constrained by the swap device interleave stripe size. 407 * 408 * Currently we hardwire nsw_wcount_async to 4. This limit is 409 * designed to prevent other I/O from having high latencies due to 410 * our pageout I/O. The value 4 works well for one or two active swap 411 * devices but is probably a little low if you have more. Even so, 412 * a higher value would probably generate only a limited improvement 413 * with three or four active swap devices since the system does not 414 * typically have to pageout at extreme bandwidths. We will want 415 * at least 2 per swap devices, and 4 is a pretty good value if you 416 * have one NFS swap device due to the command/ack latency over NFS. 417 * So it all works out pretty well. 418 */ 419 420 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER); 421 422 nsw_rcount = (nswbuf_kva + 1) / 2; 423 nsw_wcount_sync = (nswbuf_kva + 3) / 4; 424 nsw_wcount_async = 4; 425 nsw_wcount_async_max = nsw_wcount_async; 426 427 /* 428 * The zone is dynamically allocated so generally size it to 429 * maxswzone (32MB to 256GB of KVM). Set a minimum size based 430 * on physical memory of around 8x (each swblock can hold 16 pages). 431 * 432 * With the advent of SSDs (vs HDs) the practical (swap:memory) ratio 433 * has increased dramatically. 434 */ 435 n = vmstats.v_page_count / 2; 436 if (maxswzone && n < maxswzone / sizeof(struct swblock)) 437 n = maxswzone / sizeof(struct swblock); 438 n2 = n; 439 440 do { 441 swap_zone = zinit( 442 "SWAPMETA", 443 sizeof(struct swblock), 444 n, 445 ZONE_INTERRUPT); 446 if (swap_zone != NULL) 447 break; 448 /* 449 * if the allocation failed, try a zone two thirds the 450 * size of the previous attempt. 451 */ 452 n -= ((n + 2) / 3); 453 } while (n > 0); 454 455 if (swap_zone == NULL) 456 panic("swap_pager_swap_init: swap_zone == NULL"); 457 if (n2 != n) 458 kprintf("Swap zone entries reduced from %d to %d.\n", n2, n); 459 } 460 461 /* 462 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 463 * its metadata structures. 464 * 465 * This routine is called from the mmap and fork code to create a new 466 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object 467 * and then converting it with swp_pager_meta_convert(). 468 * 469 * We only support unnamed objects. 470 * 471 * No restrictions. 472 */ 473 vm_object_t 474 swap_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t offset) 475 { 476 vm_object_t object; 477 478 KKASSERT(handle == NULL); 479 object = vm_object_allocate_hold(OBJT_DEFAULT, 480 OFF_TO_IDX(offset + PAGE_MASK + size)); 481 swp_pager_meta_convert(object); 482 vm_object_drop(object); 483 484 return (object); 485 } 486 487 /* 488 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 489 * 490 * The swap backing for the object is destroyed. The code is 491 * designed such that we can reinstantiate it later, but this 492 * routine is typically called only when the entire object is 493 * about to be destroyed. 494 * 495 * The object must be locked or unreferenceable. 496 * No other requirements. 497 */ 498 static void 499 swap_pager_dealloc(vm_object_t object) 500 { 501 vm_object_hold(object); 502 vm_object_pip_wait(object, "swpdea"); 503 504 /* 505 * Free all remaining metadata. We only bother to free it from 506 * the swap meta data. We do not attempt to free swapblk's still 507 * associated with vm_page_t's for this object. We do not care 508 * if paging is still in progress on some objects. 509 */ 510 swp_pager_meta_free_all(object); 511 vm_object_drop(object); 512 } 513 514 /************************************************************************ 515 * SWAP PAGER BITMAP ROUTINES * 516 ************************************************************************/ 517 518 /* 519 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 520 * 521 * Allocate swap for the requested number of pages. The starting 522 * swap block number (a page index) is returned or SWAPBLK_NONE 523 * if the allocation failed. 524 * 525 * Also has the side effect of advising that somebody made a mistake 526 * when they configured swap and didn't configure enough. 527 * 528 * The caller must hold the object. 529 * This routine may not block. 530 */ 531 static __inline swblk_t 532 swp_pager_getswapspace(vm_object_t object, int npages) 533 { 534 swblk_t blk; 535 536 lwkt_gettoken(&vm_token); 537 blk = blist_allocat(swapblist, npages, swapiterator); 538 if (blk == SWAPBLK_NONE) 539 blk = blist_allocat(swapblist, npages, 0); 540 if (blk == SWAPBLK_NONE) { 541 if (swap_pager_full != 2) { 542 if (vm_swap_max == 0) { 543 krateprintf(&kswaprate, 544 "Warning: The system would like to " 545 "page to swap but no swap space " 546 "is configured!\n"); 547 } else { 548 krateprintf(&kswaprate, 549 "swap_pager_getswapspace: " 550 "swap full allocating %d pages\n", 551 npages); 552 } 553 swap_pager_full = 2; 554 if (swap_pager_almost_full == 0) 555 swap_fail_ticks = ticks; 556 swap_pager_almost_full = 1; 557 } 558 } else { 559 /* swapiterator = blk; disable for now, doesn't work well */ 560 swapacctspace(blk, -npages); 561 if (object->type == OBJT_SWAP) 562 vm_swap_anon_use += npages; 563 else 564 vm_swap_cache_use += npages; 565 swp_sizecheck(); 566 } 567 lwkt_reltoken(&vm_token); 568 return(blk); 569 } 570 571 /* 572 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 573 * 574 * This routine returns the specified swap blocks back to the bitmap. 575 * 576 * Note: This routine may not block (it could in the old swap code), 577 * and through the use of the new blist routines it does not block. 578 * 579 * This routine may not block. 580 */ 581 582 static __inline void 583 swp_pager_freeswapspace(vm_object_t object, swblk_t blk, int npages) 584 { 585 struct swdevt *sp = &swdevt[BLK2DEVIDX(blk)]; 586 587 lwkt_gettoken(&vm_token); 588 sp->sw_nused -= npages; 589 if (object->type == OBJT_SWAP) 590 vm_swap_anon_use -= npages; 591 else 592 vm_swap_cache_use -= npages; 593 594 if (sp->sw_flags & SW_CLOSING) { 595 lwkt_reltoken(&vm_token); 596 return; 597 } 598 599 blist_free(swapblist, blk, npages); 600 vm_swap_size += npages; 601 swp_sizecheck(); 602 lwkt_reltoken(&vm_token); 603 } 604 605 /* 606 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 607 * range within an object. 608 * 609 * This is a globally accessible routine. 610 * 611 * This routine removes swapblk assignments from swap metadata. 612 * 613 * The external callers of this routine typically have already destroyed 614 * or renamed vm_page_t's associated with this range in the object so 615 * we should be ok. 616 * 617 * No requirements. 618 */ 619 void 620 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_pindex_t size) 621 { 622 if (object->swblock_count == 0) 623 return; 624 vm_object_hold(object); 625 swp_pager_meta_free(object, start, size); 626 vm_object_drop(object); 627 } 628 629 /* 630 * No requirements. 631 */ 632 void 633 swap_pager_freespace_all(vm_object_t object) 634 { 635 if (object->swblock_count == 0) 636 return; 637 vm_object_hold(object); 638 swp_pager_meta_free_all(object); 639 vm_object_drop(object); 640 } 641 642 /* 643 * This function conditionally frees swap cache swap starting at 644 * (*basei) in the object. (count) swap blocks will be nominally freed. 645 * The actual number of blocks freed can be more or less than the 646 * requested number. 647 * 648 * This function nominally returns the number of blocks freed. However, 649 * the actual number of blocks freed may be less then the returned value. 650 * If the function is unable to exhaust the object or if it is able to 651 * free (approximately) the requested number of blocks it returns 652 * a value n > count. 653 * 654 * If we exhaust the object we will return a value n <= count. 655 * 656 * The caller must hold the object. 657 * 658 * WARNING! If count == 0 then -1 can be returned as a degenerate case, 659 * callers should always pass a count value > 0. 660 */ 661 static int swap_pager_condfree_callback(struct swblock *swap, void *data); 662 663 int 664 swap_pager_condfree(vm_object_t object, vm_pindex_t *basei, int count) 665 { 666 struct swfreeinfo info; 667 int n; 668 int t; 669 670 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 671 672 info.object = object; 673 info.basei = *basei; /* skip up to this page index */ 674 info.begi = count; /* max swap pages to destroy */ 675 info.endi = count * 8; /* max swblocks to scan */ 676 677 swblock_rb_tree_RB_SCAN(&object->swblock_root, rb_swblock_condcmp, 678 swap_pager_condfree_callback, &info); 679 *basei = info.basei; 680 681 /* 682 * Take the higher difference swblocks vs pages 683 */ 684 n = count - (int)info.begi; 685 t = count * 8 - (int)info.endi; 686 if (n < t) 687 n = t; 688 if (n < 1) 689 n = 1; 690 return(n); 691 } 692 693 /* 694 * The idea is to free whole meta-block to avoid fragmenting 695 * the swap space or disk I/O. We only do this if NO VM pages 696 * are present. 697 * 698 * We do not have to deal with clearing PG_SWAPPED in related VM 699 * pages because there are no related VM pages. 700 * 701 * The caller must hold the object. 702 */ 703 static int 704 swap_pager_condfree_callback(struct swblock *swap, void *data) 705 { 706 struct swfreeinfo *info = data; 707 vm_object_t object = info->object; 708 int i; 709 710 for (i = 0; i < SWAP_META_PAGES; ++i) { 711 if (vm_page_lookup(object, swap->swb_index + i)) 712 break; 713 } 714 info->basei = swap->swb_index + SWAP_META_PAGES; 715 if (i == SWAP_META_PAGES) { 716 info->begi -= swap->swb_count; 717 swap_pager_freespace(object, swap->swb_index, SWAP_META_PAGES); 718 } 719 --info->endi; 720 if ((int)info->begi < 0 || (int)info->endi < 0) 721 return(-1); 722 lwkt_yield(); 723 return(0); 724 } 725 726 /* 727 * Called by vm_page_alloc() when a new VM page is inserted 728 * into a VM object. Checks whether swap has been assigned to 729 * the page and sets PG_SWAPPED as necessary. 730 * 731 * (m) must be busied by caller and remains busied on return. 732 */ 733 void 734 swap_pager_page_inserted(vm_page_t m) 735 { 736 if (m->object->swblock_count) { 737 vm_object_hold(m->object); 738 if (swp_pager_meta_ctl(m->object, m->pindex, 0) != SWAPBLK_NONE) 739 vm_page_flag_set(m, PG_SWAPPED); 740 vm_object_drop(m->object); 741 } 742 } 743 744 /* 745 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 746 * 747 * Assigns swap blocks to the specified range within the object. The 748 * swap blocks are not zerod. Any previous swap assignment is destroyed. 749 * 750 * Returns 0 on success, -1 on failure. 751 * 752 * The caller is responsible for avoiding races in the specified range. 753 * No other requirements. 754 */ 755 int 756 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 757 { 758 int n = 0; 759 swblk_t blk = SWAPBLK_NONE; 760 vm_pindex_t beg = start; /* save start index */ 761 762 vm_object_hold(object); 763 764 while (size) { 765 if (n == 0) { 766 n = BLIST_MAX_ALLOC; 767 while ((blk = swp_pager_getswapspace(object, n)) == 768 SWAPBLK_NONE) 769 { 770 n >>= 1; 771 if (n == 0) { 772 swp_pager_meta_free(object, beg, 773 start - beg); 774 vm_object_drop(object); 775 return(-1); 776 } 777 } 778 } 779 swp_pager_meta_build(object, start, blk); 780 --size; 781 ++start; 782 ++blk; 783 --n; 784 } 785 swp_pager_meta_free(object, start, n); 786 vm_object_drop(object); 787 return(0); 788 } 789 790 /* 791 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 792 * and destroy the source. 793 * 794 * Copy any valid swapblks from the source to the destination. In 795 * cases where both the source and destination have a valid swapblk, 796 * we keep the destination's. 797 * 798 * This routine is allowed to block. It may block allocating metadata 799 * indirectly through swp_pager_meta_build() or if paging is still in 800 * progress on the source. 801 * 802 * XXX vm_page_collapse() kinda expects us not to block because we 803 * supposedly do not need to allocate memory, but for the moment we 804 * *may* have to get a little memory from the zone allocator, but 805 * it is taken from the interrupt memory. We should be ok. 806 * 807 * The source object contains no vm_page_t's (which is just as well) 808 * The source object is of type OBJT_SWAP. 809 * 810 * The source and destination objects must be held by the caller. 811 */ 812 void 813 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 814 vm_pindex_t base_index, int destroysource) 815 { 816 vm_pindex_t i; 817 818 ASSERT_LWKT_TOKEN_HELD(vm_object_token(srcobject)); 819 ASSERT_LWKT_TOKEN_HELD(vm_object_token(dstobject)); 820 821 /* 822 * transfer source to destination. 823 */ 824 for (i = 0; i < dstobject->size; ++i) { 825 swblk_t dstaddr; 826 827 /* 828 * Locate (without changing) the swapblk on the destination, 829 * unless it is invalid in which case free it silently, or 830 * if the destination is a resident page, in which case the 831 * source is thrown away. 832 */ 833 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 834 835 if (dstaddr == SWAPBLK_NONE) { 836 /* 837 * Destination has no swapblk and is not resident, 838 * copy source. 839 */ 840 swblk_t srcaddr; 841 842 srcaddr = swp_pager_meta_ctl(srcobject, 843 base_index + i, SWM_POP); 844 845 if (srcaddr != SWAPBLK_NONE) 846 swp_pager_meta_build(dstobject, i, srcaddr); 847 } else { 848 /* 849 * Destination has valid swapblk or it is represented 850 * by a resident page. We destroy the sourceblock. 851 */ 852 swp_pager_meta_ctl(srcobject, base_index + i, SWM_FREE); 853 } 854 } 855 856 /* 857 * Free left over swap blocks in source. 858 * 859 * We have to revert the type to OBJT_DEFAULT so we do not accidently 860 * double-remove the object from the swap queues. 861 */ 862 if (destroysource) { 863 /* 864 * Reverting the type is not necessary, the caller is going 865 * to destroy srcobject directly, but I'm doing it here 866 * for consistency since we've removed the object from its 867 * queues. 868 */ 869 swp_pager_meta_free_all(srcobject); 870 if (srcobject->type == OBJT_SWAP) 871 srcobject->type = OBJT_DEFAULT; 872 } 873 } 874 875 /* 876 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 877 * the requested page. 878 * 879 * We determine whether good backing store exists for the requested 880 * page and return TRUE if it does, FALSE if it doesn't. 881 * 882 * If TRUE, we also try to determine how much valid, contiguous backing 883 * store exists before and after the requested page within a reasonable 884 * distance. We do not try to restrict it to the swap device stripe 885 * (that is handled in getpages/putpages). It probably isn't worth 886 * doing here. 887 * 888 * No requirements. 889 */ 890 boolean_t 891 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex) 892 { 893 swblk_t blk0; 894 895 /* 896 * do we have good backing store at the requested index ? 897 */ 898 vm_object_hold(object); 899 blk0 = swp_pager_meta_ctl(object, pindex, 0); 900 901 if (blk0 == SWAPBLK_NONE) { 902 vm_object_drop(object); 903 return (FALSE); 904 } 905 vm_object_drop(object); 906 return (TRUE); 907 } 908 909 /* 910 * Object must be held exclusive or shared by the caller. 911 */ 912 boolean_t 913 swap_pager_haspage_locked(vm_object_t object, vm_pindex_t pindex) 914 { 915 if (swp_pager_meta_ctl(object, pindex, 0) == SWAPBLK_NONE) 916 return FALSE; 917 return TRUE; 918 } 919 920 /* 921 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 922 * 923 * This removes any associated swap backing store, whether valid or 924 * not, from the page. This operates on any VM object, not just OBJT_SWAP 925 * objects. 926 * 927 * This routine is typically called when a page is made dirty, at 928 * which point any associated swap can be freed. MADV_FREE also 929 * calls us in a special-case situation 930 * 931 * NOTE!!! If the page is clean and the swap was valid, the caller 932 * should make the page dirty before calling this routine. 933 * This routine does NOT change the m->dirty status of the page. 934 * Also: MADV_FREE depends on it. 935 * 936 * The page must be busied. 937 * The caller can hold the object to avoid blocking, else we might block. 938 * No other requirements. 939 */ 940 void 941 swap_pager_unswapped(vm_page_t m) 942 { 943 if (m->flags & PG_SWAPPED) { 944 vm_object_hold(m->object); 945 KKASSERT(m->flags & PG_SWAPPED); 946 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); 947 vm_page_flag_clear(m, PG_SWAPPED); 948 vm_object_drop(m->object); 949 } 950 } 951 952 /* 953 * SWAP_PAGER_STRATEGY() - read, write, free blocks 954 * 955 * This implements a VM OBJECT strategy function using swap backing store. 956 * This can operate on any VM OBJECT type, not necessarily just OBJT_SWAP 957 * types. Only BUF_CMD_{READ,WRITE,FREEBLKS} is supported, any other 958 * requests will return EINVAL. 959 * 960 * This is intended to be a cacheless interface (i.e. caching occurs at 961 * higher levels), and is also used as a swap-based SSD cache for vnode 962 * and device objects. 963 * 964 * All I/O goes directly to and from the swap device. 965 * 966 * We currently attempt to run I/O synchronously or asynchronously as 967 * the caller requests. This isn't perfect because we loose error 968 * sequencing when we run multiple ops in parallel to satisfy a request. 969 * But this is swap, so we let it all hang out. 970 * 971 * NOTE: This function supports the KVABIO API wherein bp->b_data might 972 * not be synchronized to the current cpu. 973 * 974 * No requirements. 975 */ 976 void 977 swap_pager_strategy(vm_object_t object, struct bio *bio) 978 { 979 struct buf *bp = bio->bio_buf; 980 struct bio *nbio; 981 vm_pindex_t start; 982 vm_pindex_t biox_blkno = 0; 983 int count; 984 char *data; 985 struct bio *biox; 986 struct buf *bufx; 987 #if 0 988 struct bio_track *track; 989 #endif 990 991 #if 0 992 /* 993 * tracking for swapdev vnode I/Os 994 */ 995 if (bp->b_cmd == BUF_CMD_READ) 996 track = &swapdev_vp->v_track_read; 997 else 998 track = &swapdev_vp->v_track_write; 999 #endif 1000 1001 /* 1002 * Only supported commands 1003 */ 1004 if (bp->b_cmd != BUF_CMD_FREEBLKS && 1005 bp->b_cmd != BUF_CMD_READ && 1006 bp->b_cmd != BUF_CMD_WRITE) { 1007 bp->b_error = EINVAL; 1008 bp->b_flags |= B_ERROR | B_INVAL; 1009 biodone(bio); 1010 return; 1011 } 1012 1013 /* 1014 * bcount must be an integral number of pages. 1015 */ 1016 if (bp->b_bcount & PAGE_MASK) { 1017 bp->b_error = EINVAL; 1018 bp->b_flags |= B_ERROR | B_INVAL; 1019 biodone(bio); 1020 kprintf("swap_pager_strategy: bp %p offset %lld size %d, " 1021 "not page bounded\n", 1022 bp, (long long)bio->bio_offset, (int)bp->b_bcount); 1023 return; 1024 } 1025 1026 /* 1027 * Clear error indication, initialize page index, count, data pointer. 1028 */ 1029 bp->b_error = 0; 1030 bp->b_flags &= ~B_ERROR; 1031 bp->b_resid = bp->b_bcount; 1032 1033 start = (vm_pindex_t)(bio->bio_offset >> PAGE_SHIFT); 1034 count = howmany(bp->b_bcount, PAGE_SIZE); 1035 1036 /* 1037 * WARNING! Do not dereference *data without issuing a bkvasync() 1038 */ 1039 data = bp->b_data; 1040 1041 /* 1042 * Deal with BUF_CMD_FREEBLKS 1043 */ 1044 if (bp->b_cmd == BUF_CMD_FREEBLKS) { 1045 /* 1046 * FREE PAGE(s) - destroy underlying swap that is no longer 1047 * needed. 1048 */ 1049 vm_object_hold(object); 1050 swp_pager_meta_free(object, start, count); 1051 vm_object_drop(object); 1052 bp->b_resid = 0; 1053 biodone(bio); 1054 return; 1055 } 1056 1057 /* 1058 * We need to be able to create a new cluster of I/O's. We cannot 1059 * use the caller fields of the passed bio so push a new one. 1060 * 1061 * Because nbio is just a placeholder for the cluster links, 1062 * we can biodone() the original bio instead of nbio to make 1063 * things a bit more efficient. 1064 */ 1065 nbio = push_bio(bio); 1066 nbio->bio_offset = bio->bio_offset; 1067 nbio->bio_caller_info1.cluster_head = NULL; 1068 nbio->bio_caller_info2.cluster_tail = NULL; 1069 1070 biox = NULL; 1071 bufx = NULL; 1072 1073 /* 1074 * Execute read or write 1075 */ 1076 vm_object_hold(object); 1077 1078 while (count > 0) { 1079 swblk_t blk; 1080 1081 /* 1082 * Obtain block. If block not found and writing, allocate a 1083 * new block and build it into the object. 1084 */ 1085 blk = swp_pager_meta_ctl(object, start, 0); 1086 if ((blk == SWAPBLK_NONE) && bp->b_cmd == BUF_CMD_WRITE) { 1087 blk = swp_pager_getswapspace(object, 1); 1088 if (blk == SWAPBLK_NONE) { 1089 bp->b_error = ENOMEM; 1090 bp->b_flags |= B_ERROR; 1091 break; 1092 } 1093 swp_pager_meta_build(object, start, blk); 1094 } 1095 1096 /* 1097 * Do we have to flush our current collection? Yes if: 1098 * 1099 * - no swap block at this index 1100 * - swap block is not contiguous 1101 * - we cross a physical disk boundry in the 1102 * stripe. 1103 */ 1104 if (biox && 1105 (biox_blkno + btoc(bufx->b_bcount) != blk || 1106 ((biox_blkno ^ blk) & ~SWB_DMMASK))) { 1107 switch(bp->b_cmd) { 1108 case BUF_CMD_READ: 1109 ++mycpu->gd_cnt.v_swapin; 1110 mycpu->gd_cnt.v_swappgsin += 1111 btoc(bufx->b_bcount); 1112 break; 1113 case BUF_CMD_WRITE: 1114 ++mycpu->gd_cnt.v_swapout; 1115 mycpu->gd_cnt.v_swappgsout += 1116 btoc(bufx->b_bcount); 1117 bufx->b_dirtyend = bufx->b_bcount; 1118 break; 1119 default: 1120 /* NOT REACHED */ 1121 break; 1122 } 1123 1124 /* 1125 * Finished with this buf. 1126 */ 1127 KKASSERT(bufx->b_bcount != 0); 1128 if (bufx->b_cmd != BUF_CMD_READ) 1129 bufx->b_dirtyend = bufx->b_bcount; 1130 biox = NULL; 1131 bufx = NULL; 1132 } 1133 1134 /* 1135 * Add new swapblk to biox, instantiating biox if necessary. 1136 * Zero-fill reads are able to take a shortcut. 1137 */ 1138 if (blk == SWAPBLK_NONE) { 1139 /* 1140 * We can only get here if we are reading. 1141 */ 1142 bkvasync(bp); 1143 bzero(data, PAGE_SIZE); 1144 bp->b_resid -= PAGE_SIZE; 1145 } else { 1146 if (biox == NULL) { 1147 /* XXX chain count > 4, wait to <= 4 */ 1148 1149 bufx = getpbuf(NULL); 1150 bufx->b_flags |= B_KVABIO; 1151 biox = &bufx->b_bio1; 1152 cluster_append(nbio, bufx); 1153 bufx->b_cmd = bp->b_cmd; 1154 biox->bio_done = swap_chain_iodone; 1155 biox->bio_offset = (off_t)blk << PAGE_SHIFT; 1156 biox->bio_caller_info1.cluster_parent = nbio; 1157 biox_blkno = blk; 1158 bufx->b_bcount = 0; 1159 bufx->b_data = data; 1160 } 1161 bufx->b_bcount += PAGE_SIZE; 1162 } 1163 --count; 1164 ++start; 1165 data += PAGE_SIZE; 1166 } 1167 1168 vm_object_drop(object); 1169 1170 /* 1171 * Flush out last buffer 1172 */ 1173 if (biox) { 1174 if (bufx->b_cmd == BUF_CMD_READ) { 1175 ++mycpu->gd_cnt.v_swapin; 1176 mycpu->gd_cnt.v_swappgsin += btoc(bufx->b_bcount); 1177 } else { 1178 ++mycpu->gd_cnt.v_swapout; 1179 mycpu->gd_cnt.v_swappgsout += btoc(bufx->b_bcount); 1180 bufx->b_dirtyend = bufx->b_bcount; 1181 } 1182 KKASSERT(bufx->b_bcount); 1183 if (bufx->b_cmd != BUF_CMD_READ) 1184 bufx->b_dirtyend = bufx->b_bcount; 1185 /* biox, bufx = NULL */ 1186 } 1187 1188 /* 1189 * Now initiate all the I/O. Be careful looping on our chain as 1190 * I/O's may complete while we are still initiating them. 1191 * 1192 * If the request is a 100% sparse read no bios will be present 1193 * and we just biodone() the buffer. 1194 */ 1195 nbio->bio_caller_info2.cluster_tail = NULL; 1196 bufx = nbio->bio_caller_info1.cluster_head; 1197 1198 if (bufx) { 1199 while (bufx) { 1200 biox = &bufx->b_bio1; 1201 BUF_KERNPROC(bufx); 1202 bufx = bufx->b_cluster_next; 1203 vn_strategy(swapdev_vp, biox); 1204 } 1205 } else { 1206 biodone(bio); 1207 } 1208 1209 /* 1210 * Completion of the cluster will also call biodone_chain(nbio). 1211 * We never call biodone(nbio) so we don't have to worry about 1212 * setting up a bio_done callback. It's handled in the sub-IO. 1213 */ 1214 /**/ 1215 } 1216 1217 /* 1218 * biodone callback 1219 * 1220 * No requirements. 1221 */ 1222 static void 1223 swap_chain_iodone(struct bio *biox) 1224 { 1225 struct buf **nextp; 1226 struct buf *bufx; /* chained sub-buffer */ 1227 struct bio *nbio; /* parent nbio with chain glue */ 1228 struct buf *bp; /* original bp associated with nbio */ 1229 int chain_empty; 1230 1231 bufx = biox->bio_buf; 1232 nbio = biox->bio_caller_info1.cluster_parent; 1233 bp = nbio->bio_buf; 1234 1235 /* 1236 * Update the original buffer 1237 */ 1238 KKASSERT(bp != NULL); 1239 if (bufx->b_flags & B_ERROR) { 1240 atomic_set_int(&bufx->b_flags, B_ERROR); 1241 bp->b_error = bufx->b_error; /* race ok */ 1242 } else if (bufx->b_resid != 0) { 1243 atomic_set_int(&bufx->b_flags, B_ERROR); 1244 bp->b_error = EINVAL; /* race ok */ 1245 } else { 1246 atomic_subtract_int(&bp->b_resid, bufx->b_bcount); 1247 } 1248 1249 /* 1250 * Remove us from the chain. 1251 */ 1252 spin_lock(&swapbp_spin); 1253 nextp = &nbio->bio_caller_info1.cluster_head; 1254 while (*nextp != bufx) { 1255 KKASSERT(*nextp != NULL); 1256 nextp = &(*nextp)->b_cluster_next; 1257 } 1258 *nextp = bufx->b_cluster_next; 1259 chain_empty = (nbio->bio_caller_info1.cluster_head == NULL); 1260 spin_unlock(&swapbp_spin); 1261 1262 /* 1263 * Clean up bufx. If the chain is now empty we finish out 1264 * the parent. Note that we may be racing other completions 1265 * so we must use the chain_empty status from above. 1266 */ 1267 if (chain_empty) { 1268 if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) { 1269 atomic_set_int(&bp->b_flags, B_ERROR); 1270 bp->b_error = EINVAL; 1271 } 1272 biodone_chain(nbio); 1273 } 1274 relpbuf(bufx, NULL); 1275 } 1276 1277 /* 1278 * SWAP_PAGER_GETPAGES() - bring page in from swap 1279 * 1280 * The requested page may have to be brought in from swap. Calculate the 1281 * swap block and bring in additional pages if possible. All pages must 1282 * have contiguous swap block assignments and reside in the same object. 1283 * 1284 * The caller has a single vm_object_pip_add() reference prior to 1285 * calling us and we should return with the same. 1286 * 1287 * The caller has BUSY'd the page. We should return with (*mpp) left busy, 1288 * and any additinal pages unbusied. 1289 * 1290 * If the caller encounters a PG_RAM page it will pass it to us even though 1291 * it may be valid and dirty. We cannot overwrite the page in this case! 1292 * The case is used to allow us to issue pure read-aheads. 1293 * 1294 * NOTE! XXX This code does not entirely pipeline yet due to the fact that 1295 * the PG_RAM page is validated at the same time as mreq. What we 1296 * really need to do is issue a separate read-ahead pbuf. 1297 * 1298 * No requirements. 1299 */ 1300 static int 1301 swap_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess) 1302 { 1303 struct buf *bp; 1304 struct bio *bio; 1305 vm_page_t mreq; 1306 vm_page_t m; 1307 vm_offset_t kva; 1308 swblk_t blk; 1309 int i; 1310 int j; 1311 int raonly; 1312 int error; 1313 u_int32_t busy_count; 1314 vm_page_t marray[XIO_INTERNAL_PAGES]; 1315 1316 mreq = *mpp; 1317 1318 vm_object_hold(object); 1319 if (mreq->object != object) { 1320 panic("swap_pager_getpages: object mismatch %p/%p", 1321 object, 1322 mreq->object 1323 ); 1324 } 1325 1326 /* 1327 * We don't want to overwrite a fully valid page as it might be 1328 * dirty. This case can occur when e.g. vm_fault hits a perfectly 1329 * valid page with PG_RAM set. 1330 * 1331 * In this case we see if the next page is a suitable page-in 1332 * candidate and if it is we issue read-ahead. PG_RAM will be 1333 * set on the last page of the read-ahead to continue the pipeline. 1334 */ 1335 if (mreq->valid == VM_PAGE_BITS_ALL) { 1336 if (swap_burst_read == 0 || mreq->pindex + 1 >= object->size) { 1337 vm_object_drop(object); 1338 return(VM_PAGER_OK); 1339 } 1340 blk = swp_pager_meta_ctl(object, mreq->pindex + 1, 0); 1341 if (blk == SWAPBLK_NONE) { 1342 vm_object_drop(object); 1343 return(VM_PAGER_OK); 1344 } 1345 m = vm_page_lookup_busy_try(object, mreq->pindex + 1, 1346 TRUE, &error); 1347 if (error) { 1348 vm_object_drop(object); 1349 return(VM_PAGER_OK); 1350 } else if (m == NULL) { 1351 /* 1352 * Use VM_ALLOC_QUICK to avoid blocking on cache 1353 * page reuse. 1354 */ 1355 m = vm_page_alloc(object, mreq->pindex + 1, 1356 VM_ALLOC_QUICK); 1357 if (m == NULL) { 1358 vm_object_drop(object); 1359 return(VM_PAGER_OK); 1360 } 1361 } else { 1362 if (m->valid) { 1363 vm_page_wakeup(m); 1364 vm_object_drop(object); 1365 return(VM_PAGER_OK); 1366 } 1367 vm_page_unqueue_nowakeup(m); 1368 } 1369 /* page is busy */ 1370 mreq = m; 1371 raonly = 1; 1372 } else { 1373 raonly = 0; 1374 } 1375 1376 /* 1377 * Try to block-read contiguous pages from swap if sequential, 1378 * otherwise just read one page. Contiguous pages from swap must 1379 * reside within a single device stripe because the I/O cannot be 1380 * broken up across multiple stripes. 1381 * 1382 * Note that blk and iblk can be SWAPBLK_NONE but the loop is 1383 * set up such that the case(s) are handled implicitly. 1384 */ 1385 blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0); 1386 marray[0] = mreq; 1387 1388 for (i = 1; i <= swap_burst_read && 1389 i < XIO_INTERNAL_PAGES && 1390 mreq->pindex + i < object->size; ++i) { 1391 swblk_t iblk; 1392 1393 iblk = swp_pager_meta_ctl(object, mreq->pindex + i, 0); 1394 if (iblk != blk + i) 1395 break; 1396 if ((blk ^ iblk) & ~SWB_DMMASK) 1397 break; 1398 m = vm_page_lookup_busy_try(object, mreq->pindex + i, 1399 TRUE, &error); 1400 if (error) { 1401 break; 1402 } else if (m == NULL) { 1403 /* 1404 * Use VM_ALLOC_QUICK to avoid blocking on cache 1405 * page reuse. 1406 */ 1407 m = vm_page_alloc(object, mreq->pindex + i, 1408 VM_ALLOC_QUICK); 1409 if (m == NULL) 1410 break; 1411 } else { 1412 if (m->valid) { 1413 vm_page_wakeup(m); 1414 break; 1415 } 1416 vm_page_unqueue_nowakeup(m); 1417 } 1418 /* page is busy */ 1419 marray[i] = m; 1420 } 1421 if (i > 1) 1422 vm_page_flag_set(marray[i - 1], PG_RAM); 1423 1424 /* 1425 * If mreq is the requested page and we have nothing to do return 1426 * VM_PAGER_FAIL. If raonly is set mreq is just another read-ahead 1427 * page and must be cleaned up. 1428 */ 1429 if (blk == SWAPBLK_NONE) { 1430 KKASSERT(i == 1); 1431 if (raonly) { 1432 vnode_pager_freepage(mreq); 1433 vm_object_drop(object); 1434 return(VM_PAGER_OK); 1435 } else { 1436 vm_object_drop(object); 1437 return(VM_PAGER_FAIL); 1438 } 1439 } 1440 1441 /* 1442 * Map our page(s) into kva for input 1443 * 1444 * Use the KVABIO API to avoid synchronizing the pmap. 1445 */ 1446 bp = getpbuf_kva(&nsw_rcount); 1447 bio = &bp->b_bio1; 1448 kva = (vm_offset_t) bp->b_kvabase; 1449 bcopy(marray, bp->b_xio.xio_pages, i * sizeof(vm_page_t)); 1450 pmap_qenter_noinval(kva, bp->b_xio.xio_pages, i); 1451 1452 bp->b_data = (caddr_t)kva; 1453 bp->b_bcount = PAGE_SIZE * i; 1454 bp->b_xio.xio_npages = i; 1455 bp->b_flags |= B_KVABIO; 1456 bio->bio_done = swp_pager_async_iodone; 1457 bio->bio_offset = (off_t)blk << PAGE_SHIFT; 1458 bio->bio_caller_info1.index = SWBIO_READ; 1459 1460 /* 1461 * Set index. If raonly set the index beyond the array so all 1462 * the pages are treated the same, otherwise the original mreq is 1463 * at index 0. 1464 */ 1465 if (raonly) 1466 bio->bio_driver_info = (void *)(intptr_t)i; 1467 else 1468 bio->bio_driver_info = (void *)(intptr_t)0; 1469 1470 for (j = 0; j < i; ++j) { 1471 atomic_set_int(&bp->b_xio.xio_pages[j]->busy_count, 1472 PBUSY_SWAPINPROG); 1473 } 1474 1475 mycpu->gd_cnt.v_swapin++; 1476 mycpu->gd_cnt.v_swappgsin += bp->b_xio.xio_npages; 1477 1478 /* 1479 * We still hold the lock on mreq, and our automatic completion routine 1480 * does not remove it. 1481 */ 1482 vm_object_pip_add(object, bp->b_xio.xio_npages); 1483 1484 /* 1485 * perform the I/O. NOTE!!! bp cannot be considered valid after 1486 * this point because we automatically release it on completion. 1487 * Instead, we look at the one page we are interested in which we 1488 * still hold a lock on even through the I/O completion. 1489 * 1490 * The other pages in our m[] array are also released on completion, 1491 * so we cannot assume they are valid anymore either. 1492 */ 1493 bp->b_cmd = BUF_CMD_READ; 1494 BUF_KERNPROC(bp); 1495 vn_strategy(swapdev_vp, bio); 1496 1497 /* 1498 * Wait for the page we want to complete. PBUSY_SWAPINPROG is always 1499 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1500 * is set in the meta-data. 1501 * 1502 * If this is a read-ahead only we return immediately without 1503 * waiting for I/O. 1504 */ 1505 if (raonly) { 1506 vm_object_drop(object); 1507 return(VM_PAGER_OK); 1508 } 1509 1510 /* 1511 * Read-ahead includes originally requested page case. 1512 */ 1513 for (;;) { 1514 busy_count = mreq->busy_count; 1515 cpu_ccfence(); 1516 if ((busy_count & PBUSY_SWAPINPROG) == 0) 1517 break; 1518 tsleep_interlock(mreq, 0); 1519 if (!atomic_cmpset_int(&mreq->busy_count, busy_count, 1520 busy_count | 1521 PBUSY_SWAPINPROG | PBUSY_WANTED)) { 1522 continue; 1523 } 1524 atomic_set_int(&mreq->flags, PG_REFERENCED); 1525 mycpu->gd_cnt.v_intrans++; 1526 if (tsleep(mreq, PINTERLOCKED, "swread", hz*20)) { 1527 kprintf( 1528 "swap_pager: indefinite wait buffer: " 1529 " bp %p offset: %lld, size: %ld " 1530 " m=%p busy=%08x flags=%08x\n", 1531 bp, 1532 (long long)bio->bio_offset, 1533 (long)bp->b_bcount, 1534 mreq, mreq->busy_count, mreq->flags); 1535 } 1536 } 1537 1538 /* 1539 * Disallow speculative reads prior to the SWAPINPROG test. 1540 */ 1541 cpu_lfence(); 1542 1543 /* 1544 * mreq is left busied after completion, but all the other pages 1545 * are freed. If we had an unrecoverable read error the page will 1546 * not be valid. 1547 */ 1548 vm_object_drop(object); 1549 if (mreq->valid != VM_PAGE_BITS_ALL) 1550 return(VM_PAGER_ERROR); 1551 else 1552 return(VM_PAGER_OK); 1553 1554 /* 1555 * A final note: in a low swap situation, we cannot deallocate swap 1556 * and mark a page dirty here because the caller is likely to mark 1557 * the page clean when we return, causing the page to possibly revert 1558 * to all-zero's later. 1559 */ 1560 } 1561 1562 /* 1563 * swap_pager_putpages: 1564 * 1565 * Assign swap (if necessary) and initiate I/O on the specified pages. 1566 * 1567 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1568 * are automatically converted to SWAP objects. 1569 * 1570 * In a low memory situation we may block in vn_strategy(), but the new 1571 * vm_page reservation system coupled with properly written VFS devices 1572 * should ensure that no low-memory deadlock occurs. This is an area 1573 * which needs work. 1574 * 1575 * The parent has N vm_object_pip_add() references prior to 1576 * calling us and will remove references for rtvals[] that are 1577 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1578 * completion. 1579 * 1580 * The parent has soft-busy'd the pages it passes us and will unbusy 1581 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1582 * We need to unbusy the rest on I/O completion. 1583 * 1584 * No requirements. 1585 */ 1586 void 1587 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1588 int flags, int *rtvals) 1589 { 1590 int i; 1591 int n = 0; 1592 1593 vm_object_hold(object); 1594 1595 if (count && m[0]->object != object) { 1596 panic("swap_pager_getpages: object mismatch %p/%p", 1597 object, 1598 m[0]->object 1599 ); 1600 } 1601 1602 /* 1603 * Step 1 1604 * 1605 * Turn object into OBJT_SWAP 1606 * Check for bogus sysops 1607 * 1608 * Force sync if not pageout process, we don't want any single 1609 * non-pageout process to be able to hog the I/O subsystem! This 1610 * can be overridden by setting. 1611 */ 1612 if (object->type == OBJT_DEFAULT) { 1613 if (object->type == OBJT_DEFAULT) 1614 swp_pager_meta_convert(object); 1615 } 1616 1617 /* 1618 * Normally we force synchronous swap I/O if this is not the 1619 * pageout daemon to prevent any single user process limited 1620 * via RLIMIT_RSS from hogging swap write bandwidth. 1621 */ 1622 if (curthread != pagethread && 1623 curthread != emergpager && 1624 swap_user_async == 0) { 1625 flags |= OBJPC_SYNC; 1626 } 1627 1628 /* 1629 * Step 2 1630 * 1631 * Update nsw parameters from swap_async_max sysctl values. 1632 * Do not let the sysop crash the machine with bogus numbers. 1633 */ 1634 if (swap_async_max != nsw_wcount_async_max) { 1635 int n; 1636 1637 /* 1638 * limit range 1639 */ 1640 if ((n = swap_async_max) > nswbuf_kva / 2) 1641 n = nswbuf_kva / 2; 1642 if (n < 1) 1643 n = 1; 1644 swap_async_max = n; 1645 1646 /* 1647 * Adjust difference ( if possible ). If the current async 1648 * count is too low, we may not be able to make the adjustment 1649 * at this time. 1650 * 1651 * vm_token needed for nsw_wcount sleep interlock 1652 */ 1653 lwkt_gettoken(&vm_token); 1654 n -= nsw_wcount_async_max; 1655 if (nsw_wcount_async + n >= 0) { 1656 nsw_wcount_async_max += n; 1657 pbuf_adjcount(&nsw_wcount_async, n); 1658 } 1659 lwkt_reltoken(&vm_token); 1660 } 1661 1662 /* 1663 * Step 3 1664 * 1665 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1666 * The page is left dirty until the pageout operation completes 1667 * successfully. 1668 */ 1669 1670 for (i = 0; i < count; i += n) { 1671 struct buf *bp; 1672 struct bio *bio; 1673 swblk_t blk; 1674 int j; 1675 1676 /* 1677 * Maximum I/O size is limited by a number of factors. 1678 */ 1679 1680 n = min(BLIST_MAX_ALLOC, count - i); 1681 n = min(n, nsw_cluster_max); 1682 1683 lwkt_gettoken(&vm_token); 1684 1685 /* 1686 * Get biggest block of swap we can. If we fail, fall 1687 * back and try to allocate a smaller block. Don't go 1688 * overboard trying to allocate space if it would overly 1689 * fragment swap. 1690 */ 1691 while ( 1692 (blk = swp_pager_getswapspace(object, n)) == SWAPBLK_NONE && 1693 n > 4 1694 ) { 1695 n >>= 1; 1696 } 1697 if (blk == SWAPBLK_NONE) { 1698 for (j = 0; j < n; ++j) 1699 rtvals[i+j] = VM_PAGER_FAIL; 1700 lwkt_reltoken(&vm_token); 1701 continue; 1702 } 1703 if (vm_report_swap_allocs > 0) { 1704 kprintf("swap_alloc %08jx,%d\n", (intmax_t)blk, n); 1705 --vm_report_swap_allocs; 1706 } 1707 1708 /* 1709 * The I/O we are constructing cannot cross a physical 1710 * disk boundry in the swap stripe. 1711 */ 1712 if ((blk ^ (blk + n)) & ~SWB_DMMASK) { 1713 j = ((blk + SWB_DMMAX) & ~SWB_DMMASK) - blk; 1714 swp_pager_freeswapspace(object, blk + j, n - j); 1715 n = j; 1716 } 1717 1718 /* 1719 * All I/O parameters have been satisfied, build the I/O 1720 * request and assign the swap space. 1721 * 1722 * Use the KVABIO API to avoid synchronizing the pmap. 1723 */ 1724 if ((flags & OBJPC_SYNC)) 1725 bp = getpbuf_kva(&nsw_wcount_sync); 1726 else 1727 bp = getpbuf_kva(&nsw_wcount_async); 1728 bio = &bp->b_bio1; 1729 1730 lwkt_reltoken(&vm_token); 1731 1732 pmap_qenter_noinval((vm_offset_t)bp->b_data, &m[i], n); 1733 1734 bp->b_flags |= B_KVABIO; 1735 bp->b_bcount = PAGE_SIZE * n; 1736 bio->bio_offset = (off_t)blk << PAGE_SHIFT; 1737 1738 for (j = 0; j < n; ++j) { 1739 vm_page_t mreq = m[i+j]; 1740 1741 swp_pager_meta_build(mreq->object, mreq->pindex, 1742 blk + j); 1743 if (object->type == OBJT_SWAP) 1744 vm_page_dirty(mreq); 1745 rtvals[i+j] = VM_PAGER_OK; 1746 1747 atomic_set_int(&mreq->busy_count, PBUSY_SWAPINPROG); 1748 bp->b_xio.xio_pages[j] = mreq; 1749 } 1750 bp->b_xio.xio_npages = n; 1751 1752 mycpu->gd_cnt.v_swapout++; 1753 mycpu->gd_cnt.v_swappgsout += bp->b_xio.xio_npages; 1754 1755 bp->b_dirtyoff = 0; /* req'd for NFS */ 1756 bp->b_dirtyend = bp->b_bcount; /* req'd for NFS */ 1757 bp->b_cmd = BUF_CMD_WRITE; 1758 bio->bio_caller_info1.index = SWBIO_WRITE; 1759 1760 /* 1761 * asynchronous 1762 */ 1763 if ((flags & OBJPC_SYNC) == 0) { 1764 bio->bio_done = swp_pager_async_iodone; 1765 BUF_KERNPROC(bp); 1766 vn_strategy(swapdev_vp, bio); 1767 1768 for (j = 0; j < n; ++j) 1769 rtvals[i+j] = VM_PAGER_PEND; 1770 continue; 1771 } 1772 1773 /* 1774 * Issue synchrnously. 1775 * 1776 * Wait for the sync I/O to complete, then update rtvals. 1777 * We just set the rtvals[] to VM_PAGER_PEND so we can call 1778 * our async completion routine at the end, thus avoiding a 1779 * double-free. 1780 */ 1781 bio->bio_caller_info1.index |= SWBIO_SYNC; 1782 if (flags & OBJPC_TRY_TO_CACHE) 1783 bio->bio_caller_info1.index |= SWBIO_TTC; 1784 bio->bio_done = biodone_sync; 1785 bio->bio_flags |= BIO_SYNC; 1786 vn_strategy(swapdev_vp, bio); 1787 biowait(bio, "swwrt"); 1788 1789 for (j = 0; j < n; ++j) 1790 rtvals[i+j] = VM_PAGER_PEND; 1791 1792 /* 1793 * Now that we are through with the bp, we can call the 1794 * normal async completion, which frees everything up. 1795 */ 1796 swp_pager_async_iodone(bio); 1797 } 1798 vm_object_drop(object); 1799 } 1800 1801 /* 1802 * No requirements. 1803 * 1804 * Recalculate the low and high-water marks. 1805 */ 1806 void 1807 swap_pager_newswap(void) 1808 { 1809 /* 1810 * NOTE: vm_swap_max cannot exceed 1 billion blocks, which is the 1811 * limitation imposed by the blist code. Remember that this 1812 * will be divided by NSWAP_MAX (4), so each swap device is 1813 * limited to around a terrabyte. 1814 */ 1815 if (vm_swap_max) { 1816 nswap_lowat = (int64_t)vm_swap_max * 4 / 100; /* 4% left */ 1817 nswap_hiwat = (int64_t)vm_swap_max * 6 / 100; /* 6% left */ 1818 kprintf("swap low/high-water marks set to %d/%d\n", 1819 nswap_lowat, nswap_hiwat); 1820 } else { 1821 nswap_lowat = 128; 1822 nswap_hiwat = 512; 1823 } 1824 swp_sizecheck(); 1825 } 1826 1827 /* 1828 * swp_pager_async_iodone: 1829 * 1830 * Completion routine for asynchronous reads and writes from/to swap. 1831 * Also called manually by synchronous code to finish up a bp. 1832 * 1833 * For READ operations, the pages are BUSY'd. For WRITE operations, 1834 * the pages are vm_page_t->busy'd. For READ operations, we BUSY 1835 * unbusy all pages except the 'main' request page. For WRITE 1836 * operations, we vm_page_t->busy'd unbusy all pages ( we can do this 1837 * because we marked them all VM_PAGER_PEND on return from putpages ). 1838 * 1839 * This routine may not block. 1840 * 1841 * No requirements. 1842 */ 1843 static void 1844 swp_pager_async_iodone(struct bio *bio) 1845 { 1846 struct buf *bp = bio->bio_buf; 1847 vm_object_t object = NULL; 1848 int i; 1849 int *nswptr; 1850 1851 /* 1852 * report error 1853 */ 1854 if (bp->b_flags & B_ERROR) { 1855 kprintf( 1856 "swap_pager: I/O error - %s failed; offset %lld," 1857 "size %ld, error %d\n", 1858 ((bio->bio_caller_info1.index & SWBIO_READ) ? 1859 "pagein" : "pageout"), 1860 (long long)bio->bio_offset, 1861 (long)bp->b_bcount, 1862 bp->b_error 1863 ); 1864 } 1865 1866 /* 1867 * set object. 1868 */ 1869 if (bp->b_xio.xio_npages) 1870 object = bp->b_xio.xio_pages[0]->object; 1871 1872 #if 0 1873 /* PMAP TESTING CODE (useful, keep it in but #if 0'd) */ 1874 if (bio->bio_caller_info1.index & SWBIO_WRITE) { 1875 if (bio->bio_crc != iscsi_crc32(bp->b_data, bp->b_bcount)) { 1876 kprintf("SWAPOUT: BADCRC %08x %08x\n", 1877 bio->bio_crc, 1878 iscsi_crc32(bp->b_data, bp->b_bcount)); 1879 for (i = 0; i < bp->b_xio.xio_npages; ++i) { 1880 vm_page_t m = bp->b_xio.xio_pages[i]; 1881 if ((m->flags & PG_WRITEABLE) && 1882 (pmap_mapped_sync(m) & PG_WRITEABLE)) { 1883 kprintf("SWAPOUT: " 1884 "%d/%d %p writable\n", 1885 i, bp->b_xio.xio_npages, m); 1886 } 1887 } 1888 } 1889 } 1890 #endif 1891 1892 /* 1893 * remove the mapping for kernel virtual 1894 */ 1895 pmap_qremove((vm_offset_t)bp->b_data, bp->b_xio.xio_npages); 1896 1897 /* 1898 * cleanup pages. If an error occurs writing to swap, we are in 1899 * very serious trouble. If it happens to be a disk error, though, 1900 * we may be able to recover by reassigning the swap later on. So 1901 * in this case we remove the m->swapblk assignment for the page 1902 * but do not free it in the rlist. The errornous block(s) are thus 1903 * never reallocated as swap. Redirty the page and continue. 1904 */ 1905 for (i = 0; i < bp->b_xio.xio_npages; ++i) { 1906 vm_page_t m = bp->b_xio.xio_pages[i]; 1907 1908 if (bp->b_flags & B_ERROR) { 1909 /* 1910 * If an error occurs I'd love to throw the swapblk 1911 * away without freeing it back to swapspace, so it 1912 * can never be used again. But I can't from an 1913 * interrupt. 1914 */ 1915 1916 if (bio->bio_caller_info1.index & SWBIO_READ) { 1917 /* 1918 * When reading, reqpage needs to stay 1919 * locked for the parent, but all other 1920 * pages can be freed. We still want to 1921 * wakeup the parent waiting on the page, 1922 * though. ( also: pg_reqpage can be -1 and 1923 * not match anything ). 1924 * 1925 * We have to wake specifically requested pages 1926 * up too because we cleared SWAPINPROG and 1927 * someone may be waiting for that. 1928 * 1929 * NOTE: For reads, m->dirty will probably 1930 * be overridden by the original caller 1931 * of getpages so don't play cute tricks 1932 * here. 1933 * 1934 * NOTE: We can't actually free the page from 1935 * here, because this is an interrupt. 1936 * It is not legal to mess with 1937 * object->memq from an interrupt. 1938 * Deactivate the page instead. 1939 * 1940 * WARNING! The instant SWAPINPROG is 1941 * cleared another cpu may start 1942 * using the mreq page (it will 1943 * check m->valid immediately). 1944 */ 1945 1946 m->valid = 0; 1947 atomic_clear_int(&m->busy_count, 1948 PBUSY_SWAPINPROG); 1949 1950 /* 1951 * bio_driver_info holds the requested page 1952 * index. 1953 */ 1954 if (i != (int)(intptr_t)bio->bio_driver_info) { 1955 vm_page_deactivate(m); 1956 vm_page_wakeup(m); 1957 } else { 1958 vm_page_flash(m); 1959 } 1960 /* 1961 * If i == bp->b_pager.pg_reqpage, do not wake 1962 * the page up. The caller needs to. 1963 */ 1964 } else { 1965 /* 1966 * If a write error occurs remove the swap 1967 * assignment (note that PG_SWAPPED may or 1968 * may not be set depending on prior activity). 1969 * 1970 * Re-dirty OBJT_SWAP pages as there is no 1971 * other backing store, we can't throw the 1972 * page away. 1973 * 1974 * Non-OBJT_SWAP pages (aka swapcache) must 1975 * not be dirtied since they may not have 1976 * been dirty in the first place, and they 1977 * do have backing store (the vnode). 1978 */ 1979 vm_page_busy_wait(m, FALSE, "swadpg"); 1980 vm_object_hold(m->object); 1981 swp_pager_meta_ctl(m->object, m->pindex, 1982 SWM_FREE); 1983 vm_page_flag_clear(m, PG_SWAPPED); 1984 vm_object_drop(m->object); 1985 if (m->object->type == OBJT_SWAP) { 1986 vm_page_dirty(m); 1987 vm_page_activate(m); 1988 } 1989 vm_page_io_finish(m); 1990 atomic_clear_int(&m->busy_count, 1991 PBUSY_SWAPINPROG); 1992 vm_page_wakeup(m); 1993 } 1994 } else if (bio->bio_caller_info1.index & SWBIO_READ) { 1995 /* 1996 * NOTE: for reads, m->dirty will probably be 1997 * overridden by the original caller of getpages so 1998 * we cannot set them in order to free the underlying 1999 * swap in a low-swap situation. I don't think we'd 2000 * want to do that anyway, but it was an optimization 2001 * that existed in the old swapper for a time before 2002 * it got ripped out due to precisely this problem. 2003 * 2004 * If not the requested page then deactivate it. 2005 * 2006 * Note that the requested page, reqpage, is left 2007 * busied, but we still have to wake it up. The 2008 * other pages are released (unbusied) by 2009 * vm_page_wakeup(). We do not set reqpage's 2010 * valid bits here, it is up to the caller. 2011 */ 2012 2013 /* 2014 * NOTE: Can't call pmap_clear_modify(m) from an 2015 * interrupt thread, the pmap code may have to 2016 * map non-kernel pmaps and currently asserts 2017 * the case. 2018 * 2019 * WARNING! The instant SWAPINPROG is 2020 * cleared another cpu may start 2021 * using the mreq page (it will 2022 * check m->valid immediately). 2023 */ 2024 /*pmap_clear_modify(m);*/ 2025 m->valid = VM_PAGE_BITS_ALL; 2026 vm_page_undirty(m); 2027 vm_page_flag_set(m, PG_SWAPPED); 2028 atomic_clear_int(&m->busy_count, PBUSY_SWAPINPROG); 2029 2030 /* 2031 * We have to wake specifically requested pages 2032 * up too because we cleared SWAPINPROG and 2033 * could be waiting for it in getpages. However, 2034 * be sure to not unbusy getpages specifically 2035 * requested page - getpages expects it to be 2036 * left busy. 2037 * 2038 * bio_driver_info holds the requested page 2039 */ 2040 if (i != (int)(intptr_t)bio->bio_driver_info) { 2041 vm_page_deactivate(m); 2042 vm_page_wakeup(m); 2043 } else { 2044 vm_page_flash(m); 2045 } 2046 } else { 2047 /* 2048 * Mark the page clean but do not mess with the 2049 * pmap-layer's modified state. That state should 2050 * also be clear since the caller protected the 2051 * page VM_PROT_READ, but allow the case. 2052 * 2053 * We are in an interrupt, avoid pmap operations. 2054 * 2055 * If we have a severe page deficit, deactivate the 2056 * page. Do not try to cache it (which would also 2057 * involve a pmap op), because the page might still 2058 * be read-heavy. 2059 * 2060 * When using the swap to cache clean vnode pages 2061 * we do not mess with the page dirty bits. 2062 * 2063 * NOTE! Nobody is waiting for the key mreq page 2064 * on write completion. 2065 */ 2066 vm_page_busy_wait(m, FALSE, "swadpg"); 2067 if (m->object->type == OBJT_SWAP) 2068 vm_page_undirty(m); 2069 vm_page_flag_set(m, PG_SWAPPED); 2070 atomic_clear_int(&m->busy_count, PBUSY_SWAPINPROG); 2071 if (vm_page_count_severe()) 2072 vm_page_deactivate(m); 2073 vm_page_io_finish(m); 2074 if (bio->bio_caller_info1.index & SWBIO_TTC) 2075 vm_page_try_to_cache(m); 2076 else 2077 vm_page_wakeup(m); 2078 } 2079 } 2080 2081 /* 2082 * adjust pip. NOTE: the original parent may still have its own 2083 * pip refs on the object. 2084 */ 2085 2086 if (object) 2087 vm_object_pip_wakeup_n(object, bp->b_xio.xio_npages); 2088 2089 /* 2090 * Release the physical I/O buffer. 2091 * 2092 * NOTE: Due to synchronous operations in the write case b_cmd may 2093 * already be set to BUF_CMD_DONE and BIO_SYNC may have already 2094 * been cleared. 2095 * 2096 * Use vm_token to interlock nsw_rcount/wcount wakeup? 2097 */ 2098 lwkt_gettoken(&vm_token); 2099 if (bio->bio_caller_info1.index & SWBIO_READ) 2100 nswptr = &nsw_rcount; 2101 else if (bio->bio_caller_info1.index & SWBIO_SYNC) 2102 nswptr = &nsw_wcount_sync; 2103 else 2104 nswptr = &nsw_wcount_async; 2105 bp->b_cmd = BUF_CMD_DONE; 2106 relpbuf(bp, nswptr); 2107 lwkt_reltoken(&vm_token); 2108 } 2109 2110 /* 2111 * Fault-in a potentially swapped page and remove the swap reference. 2112 * (used by swapoff code) 2113 * 2114 * object must be held. 2115 */ 2116 static __inline void 2117 swp_pager_fault_page(vm_object_t object, int *sharedp, vm_pindex_t pindex) 2118 { 2119 struct vnode *vp; 2120 vm_page_t m; 2121 int error; 2122 2123 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 2124 2125 if (object->type == OBJT_VNODE) { 2126 /* 2127 * Any swap related to a vnode is due to swapcache. We must 2128 * vget() the vnode in case it is not active (otherwise 2129 * vref() will panic). Calling vm_object_page_remove() will 2130 * ensure that any swap ref is removed interlocked with the 2131 * page. clean_only is set to TRUE so we don't throw away 2132 * dirty pages. 2133 */ 2134 vp = object->handle; 2135 error = vget(vp, LK_SHARED | LK_RETRY | LK_CANRECURSE); 2136 if (error == 0) { 2137 vm_object_page_remove(object, pindex, pindex + 1, TRUE); 2138 vput(vp); 2139 } 2140 } else { 2141 /* 2142 * Otherwise it is a normal OBJT_SWAP object and we can 2143 * fault the page in and remove the swap. 2144 */ 2145 m = vm_fault_object_page(object, IDX_TO_OFF(pindex), 2146 VM_PROT_NONE, 2147 VM_FAULT_DIRTY | VM_FAULT_UNSWAP, 2148 sharedp, &error); 2149 if (m) 2150 vm_page_unhold(m); 2151 } 2152 } 2153 2154 /* 2155 * This removes all swap blocks related to a particular device. We have 2156 * to be careful of ripups during the scan. 2157 */ 2158 static int swp_pager_swapoff_callback(struct swblock *swap, void *data); 2159 2160 int 2161 swap_pager_swapoff(int devidx) 2162 { 2163 struct vm_object_hash *hash; 2164 struct swswapoffinfo info; 2165 struct vm_object marker; 2166 vm_object_t object; 2167 int n; 2168 2169 bzero(&marker, sizeof(marker)); 2170 marker.type = OBJT_MARKER; 2171 2172 for (n = 0; n < VMOBJ_HSIZE; ++n) { 2173 hash = &vm_object_hash[n]; 2174 2175 lwkt_gettoken(&hash->token); 2176 TAILQ_INSERT_HEAD(&hash->list, &marker, object_entry); 2177 2178 while ((object = TAILQ_NEXT(&marker, object_entry)) != NULL) { 2179 if (object->type == OBJT_MARKER) 2180 goto skip; 2181 if (object->type != OBJT_SWAP && 2182 object->type != OBJT_VNODE) 2183 goto skip; 2184 vm_object_hold(object); 2185 if (object->type != OBJT_SWAP && 2186 object->type != OBJT_VNODE) { 2187 vm_object_drop(object); 2188 goto skip; 2189 } 2190 2191 /* 2192 * Object is special in that we can't just pagein 2193 * into vm_page's in it (tmpfs, vn). 2194 */ 2195 if ((object->flags & OBJ_NOPAGEIN) && 2196 RB_ROOT(&object->swblock_root)) { 2197 vm_object_drop(object); 2198 goto skip; 2199 } 2200 2201 info.object = object; 2202 info.shared = 0; 2203 info.devidx = devidx; 2204 swblock_rb_tree_RB_SCAN(&object->swblock_root, 2205 NULL, swp_pager_swapoff_callback, 2206 &info); 2207 vm_object_drop(object); 2208 skip: 2209 if (object == TAILQ_NEXT(&marker, object_entry)) { 2210 TAILQ_REMOVE(&hash->list, &marker, 2211 object_entry); 2212 TAILQ_INSERT_AFTER(&hash->list, object, 2213 &marker, object_entry); 2214 } 2215 } 2216 TAILQ_REMOVE(&hash->list, &marker, object_entry); 2217 lwkt_reltoken(&hash->token); 2218 } 2219 2220 /* 2221 * If we fail to locate all swblocks we just fail gracefully and 2222 * do not bother to restore paging on the swap device. If the 2223 * user wants to retry the user can retry. 2224 */ 2225 if (swdevt[devidx].sw_nused) 2226 return (1); 2227 else 2228 return (0); 2229 } 2230 2231 static 2232 int 2233 swp_pager_swapoff_callback(struct swblock *swap, void *data) 2234 { 2235 struct swswapoffinfo *info = data; 2236 vm_object_t object = info->object; 2237 vm_pindex_t index; 2238 swblk_t v; 2239 int i; 2240 2241 index = swap->swb_index; 2242 for (i = 0; i < SWAP_META_PAGES; ++i) { 2243 /* 2244 * Make sure we don't race a dying object. This will 2245 * kill the scan of the object's swap blocks entirely. 2246 */ 2247 if (object->flags & OBJ_DEAD) 2248 return(-1); 2249 2250 /* 2251 * Fault the page, which can obviously block. If the swap 2252 * structure disappears break out. 2253 */ 2254 v = swap->swb_pages[i]; 2255 if (v != SWAPBLK_NONE && BLK2DEVIDX(v) == info->devidx) { 2256 swp_pager_fault_page(object, &info->shared, 2257 swap->swb_index + i); 2258 /* swap ptr might go away */ 2259 if (RB_LOOKUP(swblock_rb_tree, 2260 &object->swblock_root, index) != swap) { 2261 break; 2262 } 2263 } 2264 } 2265 return(0); 2266 } 2267 2268 /************************************************************************ 2269 * SWAP META DATA * 2270 ************************************************************************ 2271 * 2272 * These routines manipulate the swap metadata stored in the 2273 * OBJT_SWAP object. 2274 * 2275 * Swap metadata is implemented with a global hash and not directly 2276 * linked into the object. Instead the object simply contains 2277 * appropriate tracking counters. 2278 */ 2279 2280 /* 2281 * Lookup the swblock containing the specified swap block index. 2282 * 2283 * The caller must hold the object. 2284 */ 2285 static __inline 2286 struct swblock * 2287 swp_pager_lookup(vm_object_t object, vm_pindex_t index) 2288 { 2289 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 2290 index &= ~(vm_pindex_t)SWAP_META_MASK; 2291 return (RB_LOOKUP(swblock_rb_tree, &object->swblock_root, index)); 2292 } 2293 2294 /* 2295 * Remove a swblock from the RB tree. 2296 * 2297 * The caller must hold the object. 2298 */ 2299 static __inline 2300 void 2301 swp_pager_remove(vm_object_t object, struct swblock *swap) 2302 { 2303 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 2304 RB_REMOVE(swblock_rb_tree, &object->swblock_root, swap); 2305 } 2306 2307 /* 2308 * Convert default object to swap object if necessary 2309 * 2310 * The caller must hold the object. 2311 */ 2312 static void 2313 swp_pager_meta_convert(vm_object_t object) 2314 { 2315 if (object->type == OBJT_DEFAULT) { 2316 object->type = OBJT_SWAP; 2317 KKASSERT(object->swblock_count == 0); 2318 } 2319 } 2320 2321 /* 2322 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 2323 * 2324 * We first convert the object to a swap object if it is a default 2325 * object. Vnode objects do not need to be converted. 2326 * 2327 * The specified swapblk is added to the object's swap metadata. If 2328 * the swapblk is not valid, it is freed instead. Any previously 2329 * assigned swapblk is freed. 2330 * 2331 * The caller must hold the object. 2332 */ 2333 static void 2334 swp_pager_meta_build(vm_object_t object, vm_pindex_t index, swblk_t swapblk) 2335 { 2336 struct swblock *swap; 2337 struct swblock *oswap; 2338 vm_pindex_t v; 2339 2340 KKASSERT(swapblk != SWAPBLK_NONE); 2341 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 2342 2343 /* 2344 * Convert object if necessary 2345 */ 2346 if (object->type == OBJT_DEFAULT) 2347 swp_pager_meta_convert(object); 2348 2349 /* 2350 * Locate swblock. If not found create, but if we aren't adding 2351 * anything just return. If we run out of space in the map we wait 2352 * and, since the hash table may have changed, retry. 2353 */ 2354 retry: 2355 swap = swp_pager_lookup(object, index); 2356 2357 if (swap == NULL) { 2358 int i; 2359 2360 swap = zalloc(swap_zone); 2361 if (swap == NULL) { 2362 vm_wait(0); 2363 goto retry; 2364 } 2365 swap->swb_index = index & ~(vm_pindex_t)SWAP_META_MASK; 2366 swap->swb_count = 0; 2367 2368 ++object->swblock_count; 2369 2370 for (i = 0; i < SWAP_META_PAGES; ++i) 2371 swap->swb_pages[i] = SWAPBLK_NONE; 2372 oswap = RB_INSERT(swblock_rb_tree, &object->swblock_root, swap); 2373 KKASSERT(oswap == NULL); 2374 } 2375 2376 /* 2377 * Delete prior contents of metadata. 2378 * 2379 * NOTE: Decrement swb_count after the freeing operation (which 2380 * might block) to prevent racing destruction of the swblock. 2381 */ 2382 index &= SWAP_META_MASK; 2383 2384 while ((v = swap->swb_pages[index]) != SWAPBLK_NONE) { 2385 swap->swb_pages[index] = SWAPBLK_NONE; 2386 /* can block */ 2387 swp_pager_freeswapspace(object, v, 1); 2388 --swap->swb_count; 2389 --mycpu->gd_vmtotal.t_vm; 2390 } 2391 2392 /* 2393 * Enter block into metadata 2394 */ 2395 swap->swb_pages[index] = swapblk; 2396 if (swapblk != SWAPBLK_NONE) { 2397 ++swap->swb_count; 2398 ++mycpu->gd_vmtotal.t_vm; 2399 } 2400 } 2401 2402 /* 2403 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2404 * 2405 * The requested range of blocks is freed, with any associated swap 2406 * returned to the swap bitmap. 2407 * 2408 * This routine will free swap metadata structures as they are cleaned 2409 * out. This routine does *NOT* operate on swap metadata associated 2410 * with resident pages. 2411 * 2412 * The caller must hold the object. 2413 */ 2414 static int swp_pager_meta_free_callback(struct swblock *swb, void *data); 2415 2416 static void 2417 swp_pager_meta_free(vm_object_t object, vm_pindex_t index, vm_pindex_t count) 2418 { 2419 struct swfreeinfo info; 2420 2421 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 2422 2423 /* 2424 * Nothing to do 2425 */ 2426 if (object->swblock_count == 0) { 2427 KKASSERT(RB_EMPTY(&object->swblock_root)); 2428 return; 2429 } 2430 if (count == 0) 2431 return; 2432 2433 /* 2434 * Setup for RB tree scan. Note that the pindex range can be huge 2435 * due to the 64 bit page index space so we cannot safely iterate. 2436 */ 2437 info.object = object; 2438 info.basei = index & ~(vm_pindex_t)SWAP_META_MASK; 2439 info.begi = index; 2440 info.endi = index + count - 1; 2441 swblock_rb_tree_RB_SCAN(&object->swblock_root, rb_swblock_scancmp, 2442 swp_pager_meta_free_callback, &info); 2443 } 2444 2445 /* 2446 * The caller must hold the object. 2447 */ 2448 static 2449 int 2450 swp_pager_meta_free_callback(struct swblock *swap, void *data) 2451 { 2452 struct swfreeinfo *info = data; 2453 vm_object_t object = info->object; 2454 int index; 2455 int eindex; 2456 2457 /* 2458 * Figure out the range within the swblock. The wider scan may 2459 * return edge-case swap blocks when the start and/or end points 2460 * are in the middle of a block. 2461 */ 2462 if (swap->swb_index < info->begi) 2463 index = (int)info->begi & SWAP_META_MASK; 2464 else 2465 index = 0; 2466 2467 if (swap->swb_index + SWAP_META_PAGES > info->endi) 2468 eindex = (int)info->endi & SWAP_META_MASK; 2469 else 2470 eindex = SWAP_META_MASK; 2471 2472 /* 2473 * Scan and free the blocks. The loop terminates early 2474 * if (swap) runs out of blocks and could be freed. 2475 * 2476 * NOTE: Decrement swb_count after swp_pager_freeswapspace() 2477 * to deal with a zfree race. 2478 */ 2479 while (index <= eindex) { 2480 swblk_t v = swap->swb_pages[index]; 2481 2482 if (v != SWAPBLK_NONE) { 2483 swap->swb_pages[index] = SWAPBLK_NONE; 2484 /* can block */ 2485 swp_pager_freeswapspace(object, v, 1); 2486 --mycpu->gd_vmtotal.t_vm; 2487 if (--swap->swb_count == 0) { 2488 swp_pager_remove(object, swap); 2489 zfree(swap_zone, swap); 2490 --object->swblock_count; 2491 break; 2492 } 2493 } 2494 ++index; 2495 } 2496 2497 /* swap may be invalid here due to zfree above */ 2498 lwkt_yield(); 2499 2500 return(0); 2501 } 2502 2503 /* 2504 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2505 * 2506 * This routine locates and destroys all swap metadata associated with 2507 * an object. 2508 * 2509 * NOTE: Decrement swb_count after the freeing operation (which 2510 * might block) to prevent racing destruction of the swblock. 2511 * 2512 * The caller must hold the object. 2513 */ 2514 static void 2515 swp_pager_meta_free_all(vm_object_t object) 2516 { 2517 struct swblock *swap; 2518 int i; 2519 2520 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 2521 2522 while ((swap = RB_ROOT(&object->swblock_root)) != NULL) { 2523 swp_pager_remove(object, swap); 2524 for (i = 0; i < SWAP_META_PAGES; ++i) { 2525 swblk_t v = swap->swb_pages[i]; 2526 if (v != SWAPBLK_NONE) { 2527 /* can block */ 2528 swp_pager_freeswapspace(object, v, 1); 2529 --swap->swb_count; 2530 --mycpu->gd_vmtotal.t_vm; 2531 } 2532 } 2533 if (swap->swb_count != 0) 2534 panic("swap_pager_meta_free_all: swb_count != 0"); 2535 zfree(swap_zone, swap); 2536 --object->swblock_count; 2537 lwkt_yield(); 2538 } 2539 KKASSERT(object->swblock_count == 0); 2540 } 2541 2542 /* 2543 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. 2544 * 2545 * This routine is capable of looking up, popping, or freeing 2546 * swapblk assignments in the swap meta data or in the vm_page_t. 2547 * The routine typically returns the swapblk being looked-up, or popped, 2548 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block 2549 * was invalid. This routine will automatically free any invalid 2550 * meta-data swapblks. 2551 * 2552 * It is not possible to store invalid swapblks in the swap meta data 2553 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking. 2554 * 2555 * When acting on a busy resident page and paging is in progress, we 2556 * have to wait until paging is complete but otherwise can act on the 2557 * busy page. 2558 * 2559 * SWM_FREE remove and free swap block from metadata 2560 * SWM_POP remove from meta data but do not free.. pop it out 2561 * 2562 * The caller must hold the object. 2563 */ 2564 static swblk_t 2565 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t index, int flags) 2566 { 2567 struct swblock *swap; 2568 swblk_t r1; 2569 2570 if (object->swblock_count == 0) 2571 return(SWAPBLK_NONE); 2572 2573 r1 = SWAPBLK_NONE; 2574 swap = swp_pager_lookup(object, index); 2575 2576 if (swap != NULL) { 2577 index &= SWAP_META_MASK; 2578 r1 = swap->swb_pages[index]; 2579 2580 if (r1 != SWAPBLK_NONE) { 2581 if (flags & (SWM_FREE|SWM_POP)) { 2582 swap->swb_pages[index] = SWAPBLK_NONE; 2583 --mycpu->gd_vmtotal.t_vm; 2584 if (--swap->swb_count == 0) { 2585 swp_pager_remove(object, swap); 2586 zfree(swap_zone, swap); 2587 --object->swblock_count; 2588 } 2589 } 2590 /* swap ptr may be invalid */ 2591 if (flags & SWM_FREE) { 2592 swp_pager_freeswapspace(object, r1, 1); 2593 r1 = SWAPBLK_NONE; 2594 } 2595 } 2596 /* swap ptr may be invalid */ 2597 } 2598 return(r1); 2599 } 2600