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