1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (c) 1998 Matthew Dillon, 5 * Copyright (c) 1994 John S. Dyson 6 * Copyright (c) 1990 University of Utah. 7 * Copyright (c) 1982, 1986, 1989, 1993 8 * The Regents of the University of California. All rights reserved. 9 * 10 * This code is derived from software contributed to Berkeley by 11 * the Systems Programming Group of the University of Utah Computer 12 * Science Department. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. All advertising materials mentioning features or use of this software 23 * must display the following acknowledgement: 24 * This product includes software developed by the University of 25 * California, Berkeley and its contributors. 26 * 4. Neither the name of the University nor the names of its contributors 27 * may be used to endorse or promote products derived from this software 28 * without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 40 * SUCH DAMAGE. 41 * 42 * New Swap System 43 * Matthew Dillon 44 * 45 * Radix Bitmap 'blists'. 46 * 47 * - The new swapper uses the new radix bitmap code. This should scale 48 * to arbitrarily small or arbitrarily large swap spaces and an almost 49 * arbitrary degree of fragmentation. 50 * 51 * Features: 52 * 53 * - on the fly reallocation of swap during putpages. The new system 54 * does not try to keep previously allocated swap blocks for dirty 55 * pages. 56 * 57 * - on the fly deallocation of swap 58 * 59 * - No more garbage collection required. Unnecessarily allocated swap 60 * blocks only exist for dirty vm_page_t's now and these are already 61 * cycled (in a high-load system) by the pager. We also do on-the-fly 62 * removal of invalidated swap blocks when a page is destroyed 63 * or renamed. 64 * 65 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$ 66 * 67 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94 68 * @(#)vm_swap.c 8.5 (Berkeley) 2/17/94 69 */ 70 71 #include <sys/cdefs.h> 72 __FBSDID("$FreeBSD$"); 73 74 #include "opt_vm.h" 75 76 #include <sys/param.h> 77 #include <sys/bio.h> 78 #include <sys/blist.h> 79 #include <sys/buf.h> 80 #include <sys/conf.h> 81 #include <sys/disk.h> 82 #include <sys/eventhandler.h> 83 #include <sys/fcntl.h> 84 #include <sys/lock.h> 85 #include <sys/kernel.h> 86 #include <sys/mount.h> 87 #include <sys/namei.h> 88 #include <sys/malloc.h> 89 #include <sys/pctrie.h> 90 #include <sys/priv.h> 91 #include <sys/proc.h> 92 #include <sys/racct.h> 93 #include <sys/resource.h> 94 #include <sys/resourcevar.h> 95 #include <sys/rwlock.h> 96 #include <sys/sbuf.h> 97 #include <sys/sysctl.h> 98 #include <sys/sysproto.h> 99 #include <sys/systm.h> 100 #include <sys/sx.h> 101 #include <sys/vmmeter.h> 102 #include <sys/vnode.h> 103 104 #include <security/mac/mac_framework.h> 105 106 #include <vm/vm.h> 107 #include <vm/pmap.h> 108 #include <vm/vm_map.h> 109 #include <vm/vm_kern.h> 110 #include <vm/vm_object.h> 111 #include <vm/vm_page.h> 112 #include <vm/vm_pager.h> 113 #include <vm/vm_pageout.h> 114 #include <vm/vm_param.h> 115 #include <vm/swap_pager.h> 116 #include <vm/vm_extern.h> 117 #include <vm/uma.h> 118 119 #include <geom/geom.h> 120 121 /* 122 * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64. 123 * The 64-page limit is due to the radix code (kern/subr_blist.c). 124 */ 125 #ifndef MAX_PAGEOUT_CLUSTER 126 #define MAX_PAGEOUT_CLUSTER 32 127 #endif 128 129 #if !defined(SWB_NPAGES) 130 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER 131 #endif 132 133 #define SWAP_META_PAGES PCTRIE_COUNT 134 135 /* 136 * A swblk structure maps each page index within a 137 * SWAP_META_PAGES-aligned and sized range to the address of an 138 * on-disk swap block (or SWAPBLK_NONE). The collection of these 139 * mappings for an entire vm object is implemented as a pc-trie. 140 */ 141 struct swblk { 142 vm_pindex_t p; 143 daddr_t d[SWAP_META_PAGES]; 144 }; 145 146 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); 147 static struct mtx sw_dev_mtx; 148 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 149 static struct swdevt *swdevhd; /* Allocate from here next */ 150 static int nswapdev; /* Number of swap devices */ 151 int swap_pager_avail; 152 static struct sx swdev_syscall_lock; /* serialize swap(on|off) */ 153 154 static u_long swap_reserved; 155 static u_long swap_total; 156 static int sysctl_page_shift(SYSCTL_HANDLER_ARGS); 157 SYSCTL_PROC(_vm, OID_AUTO, swap_reserved, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 158 &swap_reserved, 0, sysctl_page_shift, "A", 159 "Amount of swap storage needed to back all allocated anonymous memory."); 160 SYSCTL_PROC(_vm, OID_AUTO, swap_total, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 161 &swap_total, 0, sysctl_page_shift, "A", 162 "Total amount of available swap storage."); 163 164 static int overcommit = 0; 165 SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &overcommit, 0, 166 "Configure virtual memory overcommit behavior. See tuning(7) " 167 "for details."); 168 static unsigned long swzone; 169 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 170 "Actual size of swap metadata zone"); 171 static unsigned long swap_maxpages; 172 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, 173 "Maximum amount of swap supported"); 174 175 /* bits from overcommit */ 176 #define SWAP_RESERVE_FORCE_ON (1 << 0) 177 #define SWAP_RESERVE_RLIMIT_ON (1 << 1) 178 #define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2) 179 180 static int 181 sysctl_page_shift(SYSCTL_HANDLER_ARGS) 182 { 183 uint64_t newval; 184 u_long value = *(u_long *)arg1; 185 186 newval = ((uint64_t)value) << PAGE_SHIFT; 187 return (sysctl_handle_64(oidp, &newval, 0, req)); 188 } 189 190 int 191 swap_reserve(vm_ooffset_t incr) 192 { 193 194 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 195 } 196 197 int 198 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 199 { 200 u_long r, s, prev, pincr; 201 int res, error; 202 static int curfail; 203 static struct timeval lastfail; 204 struct uidinfo *uip; 205 206 uip = cred->cr_ruidinfo; 207 208 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 209 (uintmax_t)incr)); 210 211 #ifdef RACCT 212 if (racct_enable) { 213 PROC_LOCK(curproc); 214 error = racct_add(curproc, RACCT_SWAP, incr); 215 PROC_UNLOCK(curproc); 216 if (error != 0) 217 return (0); 218 } 219 #endif 220 221 pincr = atop(incr); 222 res = 0; 223 prev = atomic_fetchadd_long(&swap_reserved, pincr); 224 r = prev + pincr; 225 if (overcommit & SWAP_RESERVE_ALLOW_NONWIRED) { 226 s = vm_cnt.v_page_count - vm_cnt.v_free_reserved - 227 vm_wire_count(); 228 } else 229 s = 0; 230 s += swap_total; 231 if ((overcommit & SWAP_RESERVE_FORCE_ON) == 0 || r <= s || 232 (error = priv_check(curthread, PRIV_VM_SWAP_NOQUOTA)) == 0) { 233 res = 1; 234 } else { 235 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 236 if (prev < pincr) 237 panic("swap_reserved < incr on overcommit fail"); 238 } 239 if (res) { 240 prev = atomic_fetchadd_long(&uip->ui_vmsize, pincr); 241 if ((overcommit & SWAP_RESERVE_RLIMIT_ON) != 0 && 242 prev + pincr > lim_cur(curthread, RLIMIT_SWAP) && 243 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT)) { 244 res = 0; 245 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pincr); 246 if (prev < pincr) 247 panic("uip->ui_vmsize < incr on overcommit fail"); 248 } 249 } 250 if (!res && ppsratecheck(&lastfail, &curfail, 1)) { 251 printf("uid %d, pid %d: swap reservation for %jd bytes failed\n", 252 uip->ui_uid, curproc->p_pid, incr); 253 } 254 255 #ifdef RACCT 256 if (racct_enable && !res) { 257 PROC_LOCK(curproc); 258 racct_sub(curproc, RACCT_SWAP, incr); 259 PROC_UNLOCK(curproc); 260 } 261 #endif 262 263 return (res); 264 } 265 266 void 267 swap_reserve_force(vm_ooffset_t incr) 268 { 269 struct uidinfo *uip; 270 u_long pincr; 271 272 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 273 (uintmax_t)incr)); 274 275 PROC_LOCK(curproc); 276 #ifdef RACCT 277 if (racct_enable) 278 racct_add_force(curproc, RACCT_SWAP, incr); 279 #endif 280 pincr = atop(incr); 281 atomic_add_long(&swap_reserved, pincr); 282 uip = curproc->p_ucred->cr_ruidinfo; 283 atomic_add_long(&uip->ui_vmsize, pincr); 284 PROC_UNLOCK(curproc); 285 } 286 287 void 288 swap_release(vm_ooffset_t decr) 289 { 290 struct ucred *cred; 291 292 PROC_LOCK(curproc); 293 cred = curproc->p_ucred; 294 swap_release_by_cred(decr, cred); 295 PROC_UNLOCK(curproc); 296 } 297 298 void 299 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 300 { 301 u_long prev, pdecr; 302 struct uidinfo *uip; 303 304 uip = cred->cr_ruidinfo; 305 306 KASSERT((decr & PAGE_MASK) == 0, ("%s: decr: %ju & PAGE_MASK", __func__, 307 (uintmax_t)decr)); 308 309 pdecr = atop(decr); 310 prev = atomic_fetchadd_long(&swap_reserved, -pdecr); 311 if (prev < pdecr) 312 panic("swap_reserved < decr"); 313 314 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pdecr); 315 if (prev < pdecr) 316 printf("negative vmsize for uid = %d\n", uip->ui_uid); 317 #ifdef RACCT 318 if (racct_enable) 319 racct_sub_cred(cred, RACCT_SWAP, decr); 320 #endif 321 } 322 323 #define SWM_POP 0x01 /* pop out */ 324 325 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 326 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 327 static struct mtx swbuf_mtx; /* to sync nsw_wcount_async */ 328 static int nsw_wcount_async; /* limit async write buffers */ 329 static int nsw_wcount_async_max;/* assigned maximum */ 330 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 331 332 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 333 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 334 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 335 "Maximum running async swap ops"); 336 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS); 337 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD | 338 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A", 339 "Swap Fragmentation Info"); 340 341 static struct sx sw_alloc_sx; 342 343 /* 344 * "named" and "unnamed" anon region objects. Try to reduce the overhead 345 * of searching a named list by hashing it just a little. 346 */ 347 348 #define NOBJLISTS 8 349 350 #define NOBJLIST(handle) \ 351 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 352 353 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 354 static uma_zone_t swwbuf_zone; 355 static uma_zone_t swrbuf_zone; 356 static uma_zone_t swblk_zone; 357 static uma_zone_t swpctrie_zone; 358 359 /* 360 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 361 * calls hooked from other parts of the VM system and do not appear here. 362 * (see vm/swap_pager.h). 363 */ 364 static vm_object_t 365 swap_pager_alloc(void *handle, vm_ooffset_t size, 366 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 367 static void swap_pager_dealloc(vm_object_t object); 368 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, 369 int *); 370 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, 371 int *, pgo_getpages_iodone_t, void *); 372 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 373 static boolean_t 374 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 375 static void swap_pager_init(void); 376 static void swap_pager_unswapped(vm_page_t); 377 static void swap_pager_swapoff(struct swdevt *sp); 378 379 struct pagerops swappagerops = { 380 .pgo_init = swap_pager_init, /* early system initialization of pager */ 381 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 382 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 383 .pgo_getpages = swap_pager_getpages, /* pagein */ 384 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 385 .pgo_putpages = swap_pager_putpages, /* pageout */ 386 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 387 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 388 }; 389 390 /* 391 * swap_*() routines are externally accessible. swp_*() routines are 392 * internal. 393 */ 394 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 395 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 396 397 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 398 "Maximum size of a swap block in pages"); 399 400 static void swp_sizecheck(void); 401 static void swp_pager_async_iodone(struct buf *bp); 402 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit); 403 static int swapongeom(struct vnode *); 404 static int swaponvp(struct thread *, struct vnode *, u_long); 405 static int swapoff_one(struct swdevt *sp, struct ucred *cred); 406 407 /* 408 * Swap bitmap functions 409 */ 410 static void swp_pager_freeswapspace(daddr_t blk, daddr_t npages); 411 static daddr_t swp_pager_getswapspace(int *npages, int limit); 412 413 /* 414 * Metadata functions 415 */ 416 static daddr_t swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 417 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 418 static void swp_pager_meta_free_all(vm_object_t); 419 static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 420 421 static void 422 swp_pager_init_freerange(daddr_t *start, daddr_t *num) 423 { 424 425 *start = SWAPBLK_NONE; 426 *num = 0; 427 } 428 429 static void 430 swp_pager_update_freerange(daddr_t *start, daddr_t *num, daddr_t addr) 431 { 432 433 if (*start + *num == addr) { 434 (*num)++; 435 } else { 436 swp_pager_freeswapspace(*start, *num); 437 *start = addr; 438 *num = 1; 439 } 440 } 441 442 static void * 443 swblk_trie_alloc(struct pctrie *ptree) 444 { 445 446 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? 447 M_USE_RESERVE : 0))); 448 } 449 450 static void 451 swblk_trie_free(struct pctrie *ptree, void *node) 452 { 453 454 uma_zfree(swpctrie_zone, node); 455 } 456 457 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); 458 459 /* 460 * SWP_SIZECHECK() - update swap_pager_full indication 461 * 462 * update the swap_pager_almost_full indication and warn when we are 463 * about to run out of swap space, using lowat/hiwat hysteresis. 464 * 465 * Clear swap_pager_full ( task killing ) indication when lowat is met. 466 * 467 * No restrictions on call 468 * This routine may not block. 469 */ 470 static void 471 swp_sizecheck(void) 472 { 473 474 if (swap_pager_avail < nswap_lowat) { 475 if (swap_pager_almost_full == 0) { 476 printf("swap_pager: out of swap space\n"); 477 swap_pager_almost_full = 1; 478 } 479 } else { 480 swap_pager_full = 0; 481 if (swap_pager_avail > nswap_hiwat) 482 swap_pager_almost_full = 0; 483 } 484 } 485 486 /* 487 * SWAP_PAGER_INIT() - initialize the swap pager! 488 * 489 * Expected to be started from system init. NOTE: This code is run 490 * before much else so be careful what you depend on. Most of the VM 491 * system has yet to be initialized at this point. 492 */ 493 static void 494 swap_pager_init(void) 495 { 496 /* 497 * Initialize object lists 498 */ 499 int i; 500 501 for (i = 0; i < NOBJLISTS; ++i) 502 TAILQ_INIT(&swap_pager_object_list[i]); 503 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 504 sx_init(&sw_alloc_sx, "swspsx"); 505 sx_init(&swdev_syscall_lock, "swsysc"); 506 } 507 508 /* 509 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 510 * 511 * Expected to be started from pageout process once, prior to entering 512 * its main loop. 513 */ 514 void 515 swap_pager_swap_init(void) 516 { 517 unsigned long n, n2; 518 519 /* 520 * Number of in-transit swap bp operations. Don't 521 * exhaust the pbufs completely. Make sure we 522 * initialize workable values (0 will work for hysteresis 523 * but it isn't very efficient). 524 * 525 * The nsw_cluster_max is constrained by the bp->b_pages[] 526 * array, which has MAXPHYS / PAGE_SIZE entries, and our locally 527 * defined MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 528 * constrained by the swap device interleave stripe size. 529 * 530 * Currently we hardwire nsw_wcount_async to 4. This limit is 531 * designed to prevent other I/O from having high latencies due to 532 * our pageout I/O. The value 4 works well for one or two active swap 533 * devices but is probably a little low if you have more. Even so, 534 * a higher value would probably generate only a limited improvement 535 * with three or four active swap devices since the system does not 536 * typically have to pageout at extreme bandwidths. We will want 537 * at least 2 per swap devices, and 4 is a pretty good value if you 538 * have one NFS swap device due to the command/ack latency over NFS. 539 * So it all works out pretty well. 540 */ 541 nsw_cluster_max = min(MAXPHYS / PAGE_SIZE, MAX_PAGEOUT_CLUSTER); 542 543 nsw_wcount_async = 4; 544 nsw_wcount_async_max = nsw_wcount_async; 545 mtx_init(&swbuf_mtx, "async swbuf mutex", NULL, MTX_DEF); 546 547 swwbuf_zone = pbuf_zsecond_create("swwbuf", nswbuf / 4); 548 swrbuf_zone = pbuf_zsecond_create("swrbuf", nswbuf / 2); 549 550 /* 551 * Initialize our zone, taking the user's requested size or 552 * estimating the number we need based on the number of pages 553 * in the system. 554 */ 555 n = maxswzone != 0 ? maxswzone / sizeof(struct swblk) : 556 vm_cnt.v_page_count / 2; 557 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, 558 pctrie_zone_init, NULL, UMA_ALIGN_PTR, UMA_ZONE_VM); 559 if (swpctrie_zone == NULL) 560 panic("failed to create swap pctrie zone."); 561 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, 562 NULL, NULL, _Alignof(struct swblk) - 1, UMA_ZONE_VM); 563 if (swblk_zone == NULL) 564 panic("failed to create swap blk zone."); 565 n2 = n; 566 do { 567 if (uma_zone_reserve_kva(swblk_zone, n)) 568 break; 569 /* 570 * if the allocation failed, try a zone two thirds the 571 * size of the previous attempt. 572 */ 573 n -= ((n + 2) / 3); 574 } while (n > 0); 575 576 /* 577 * Often uma_zone_reserve_kva() cannot reserve exactly the 578 * requested size. Account for the difference when 579 * calculating swap_maxpages. 580 */ 581 n = uma_zone_get_max(swblk_zone); 582 583 if (n < n2) 584 printf("Swap blk zone entries changed from %lu to %lu.\n", 585 n2, n); 586 swap_maxpages = n * SWAP_META_PAGES; 587 swzone = n * sizeof(struct swblk); 588 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 589 printf("Cannot reserve swap pctrie zone, " 590 "reduce kern.maxswzone.\n"); 591 } 592 593 static vm_object_t 594 swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size, 595 vm_ooffset_t offset) 596 { 597 vm_object_t object; 598 599 if (cred != NULL) { 600 if (!swap_reserve_by_cred(size, cred)) 601 return (NULL); 602 crhold(cred); 603 } 604 605 /* 606 * The un_pager.swp.swp_blks trie is initialized by 607 * vm_object_allocate() to ensure the correct order of 608 * visibility to other threads. 609 */ 610 object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset + 611 PAGE_MASK + size)); 612 613 object->handle = handle; 614 if (cred != NULL) { 615 object->cred = cred; 616 object->charge = size; 617 } 618 return (object); 619 } 620 621 /* 622 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 623 * its metadata structures. 624 * 625 * This routine is called from the mmap and fork code to create a new 626 * OBJT_SWAP object. 627 * 628 * This routine must ensure that no live duplicate is created for 629 * the named object request, which is protected against by 630 * holding the sw_alloc_sx lock in case handle != NULL. 631 */ 632 static vm_object_t 633 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 634 vm_ooffset_t offset, struct ucred *cred) 635 { 636 vm_object_t object; 637 638 if (handle != NULL) { 639 /* 640 * Reference existing named region or allocate new one. There 641 * should not be a race here against swp_pager_meta_build() 642 * as called from vm_page_remove() in regards to the lookup 643 * of the handle. 644 */ 645 sx_xlock(&sw_alloc_sx); 646 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 647 if (object == NULL) { 648 object = swap_pager_alloc_init(handle, cred, size, 649 offset); 650 if (object != NULL) { 651 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 652 object, pager_object_list); 653 } 654 } 655 sx_xunlock(&sw_alloc_sx); 656 } else { 657 object = swap_pager_alloc_init(handle, cred, size, offset); 658 } 659 return (object); 660 } 661 662 /* 663 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 664 * 665 * The swap backing for the object is destroyed. The code is 666 * designed such that we can reinstantiate it later, but this 667 * routine is typically called only when the entire object is 668 * about to be destroyed. 669 * 670 * The object must be locked. 671 */ 672 static void 673 swap_pager_dealloc(vm_object_t object) 674 { 675 676 VM_OBJECT_ASSERT_WLOCKED(object); 677 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 678 679 /* 680 * Remove from list right away so lookups will fail if we block for 681 * pageout completion. 682 */ 683 if (object->handle != NULL) { 684 VM_OBJECT_WUNLOCK(object); 685 sx_xlock(&sw_alloc_sx); 686 TAILQ_REMOVE(NOBJLIST(object->handle), object, 687 pager_object_list); 688 sx_xunlock(&sw_alloc_sx); 689 VM_OBJECT_WLOCK(object); 690 } 691 692 vm_object_pip_wait(object, "swpdea"); 693 694 /* 695 * Free all remaining metadata. We only bother to free it from 696 * the swap meta data. We do not attempt to free swapblk's still 697 * associated with vm_page_t's for this object. We do not care 698 * if paging is still in progress on some objects. 699 */ 700 swp_pager_meta_free_all(object); 701 object->handle = NULL; 702 object->type = OBJT_DEAD; 703 } 704 705 /************************************************************************ 706 * SWAP PAGER BITMAP ROUTINES * 707 ************************************************************************/ 708 709 /* 710 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 711 * 712 * Allocate swap for up to the requested number of pages, and at 713 * least a minimum number of pages. The starting swap block number 714 * (a page index) is returned or SWAPBLK_NONE if the allocation 715 * failed. 716 * 717 * Also has the side effect of advising that somebody made a mistake 718 * when they configured swap and didn't configure enough. 719 * 720 * This routine may not sleep. 721 * 722 * We allocate in round-robin fashion from the configured devices. 723 */ 724 static daddr_t 725 swp_pager_getswapspace(int *io_npages, int limit) 726 { 727 daddr_t blk; 728 struct swdevt *sp; 729 int mpages, npages; 730 731 blk = SWAPBLK_NONE; 732 mpages = *io_npages; 733 npages = imin(BLIST_MAX_ALLOC, mpages); 734 mtx_lock(&sw_dev_mtx); 735 sp = swdevhd; 736 while (!TAILQ_EMPTY(&swtailq)) { 737 if (sp == NULL) 738 sp = TAILQ_FIRST(&swtailq); 739 if ((sp->sw_flags & SW_CLOSING) == 0) 740 blk = blist_alloc(sp->sw_blist, &npages, mpages); 741 if (blk != SWAPBLK_NONE) 742 break; 743 sp = TAILQ_NEXT(sp, sw_list); 744 if (swdevhd == sp) { 745 if (npages <= limit) 746 break; 747 mpages = npages - 1; 748 npages >>= 1; 749 } 750 } 751 if (blk != SWAPBLK_NONE) { 752 *io_npages = npages; 753 blk += sp->sw_first; 754 sp->sw_used += npages; 755 swap_pager_avail -= npages; 756 swp_sizecheck(); 757 swdevhd = TAILQ_NEXT(sp, sw_list); 758 } else { 759 if (swap_pager_full != 2) { 760 printf("swp_pager_getswapspace(%d): failed\n", 761 *io_npages); 762 swap_pager_full = 2; 763 swap_pager_almost_full = 1; 764 } 765 swdevhd = NULL; 766 } 767 mtx_unlock(&sw_dev_mtx); 768 return (blk); 769 } 770 771 static bool 772 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 773 { 774 775 return (blk >= sp->sw_first && blk < sp->sw_end); 776 } 777 778 static void 779 swp_pager_strategy(struct buf *bp) 780 { 781 struct swdevt *sp; 782 783 mtx_lock(&sw_dev_mtx); 784 TAILQ_FOREACH(sp, &swtailq, sw_list) { 785 if (swp_pager_isondev(bp->b_blkno, sp)) { 786 mtx_unlock(&sw_dev_mtx); 787 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 788 unmapped_buf_allowed) { 789 bp->b_data = unmapped_buf; 790 bp->b_offset = 0; 791 } else { 792 pmap_qenter((vm_offset_t)bp->b_data, 793 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 794 } 795 sp->sw_strategy(bp, sp); 796 return; 797 } 798 } 799 panic("Swapdev not found"); 800 } 801 802 803 /* 804 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 805 * 806 * This routine returns the specified swap blocks back to the bitmap. 807 * 808 * This routine may not sleep. 809 */ 810 static void 811 swp_pager_freeswapspace(daddr_t blk, daddr_t npages) 812 { 813 struct swdevt *sp; 814 815 if (npages == 0) 816 return; 817 mtx_lock(&sw_dev_mtx); 818 TAILQ_FOREACH(sp, &swtailq, sw_list) { 819 if (swp_pager_isondev(blk, sp)) { 820 sp->sw_used -= npages; 821 /* 822 * If we are attempting to stop swapping on 823 * this device, we don't want to mark any 824 * blocks free lest they be reused. 825 */ 826 if ((sp->sw_flags & SW_CLOSING) == 0) { 827 blist_free(sp->sw_blist, blk - sp->sw_first, 828 npages); 829 swap_pager_avail += npages; 830 swp_sizecheck(); 831 } 832 mtx_unlock(&sw_dev_mtx); 833 return; 834 } 835 } 836 panic("Swapdev not found"); 837 } 838 839 /* 840 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 841 */ 842 static int 843 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 844 { 845 struct sbuf sbuf; 846 struct swdevt *sp; 847 const char *devname; 848 int error; 849 850 error = sysctl_wire_old_buffer(req, 0); 851 if (error != 0) 852 return (error); 853 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 854 mtx_lock(&sw_dev_mtx); 855 TAILQ_FOREACH(sp, &swtailq, sw_list) { 856 if (vn_isdisk(sp->sw_vp, NULL)) 857 devname = devtoname(sp->sw_vp->v_rdev); 858 else 859 devname = "[file]"; 860 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 861 blist_stats(sp->sw_blist, &sbuf); 862 } 863 mtx_unlock(&sw_dev_mtx); 864 error = sbuf_finish(&sbuf); 865 sbuf_delete(&sbuf); 866 return (error); 867 } 868 869 /* 870 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 871 * range within an object. 872 * 873 * This is a globally accessible routine. 874 * 875 * This routine removes swapblk assignments from swap metadata. 876 * 877 * The external callers of this routine typically have already destroyed 878 * or renamed vm_page_t's associated with this range in the object so 879 * we should be ok. 880 * 881 * The object must be locked. 882 */ 883 void 884 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 885 { 886 887 swp_pager_meta_free(object, start, size); 888 } 889 890 /* 891 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 892 * 893 * Assigns swap blocks to the specified range within the object. The 894 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 895 * 896 * Returns 0 on success, -1 on failure. 897 */ 898 int 899 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 900 { 901 daddr_t addr, blk, n_free, s_free; 902 int i, j, n; 903 904 swp_pager_init_freerange(&s_free, &n_free); 905 VM_OBJECT_WLOCK(object); 906 for (i = 0; i < size; i += n) { 907 n = size - i; 908 blk = swp_pager_getswapspace(&n, 1); 909 if (blk == SWAPBLK_NONE) { 910 swp_pager_meta_free(object, start, i); 911 VM_OBJECT_WUNLOCK(object); 912 return (-1); 913 } 914 for (j = 0; j < n; ++j) { 915 addr = swp_pager_meta_build(object, 916 start + i + j, blk + j); 917 if (addr != SWAPBLK_NONE) 918 swp_pager_update_freerange(&s_free, &n_free, 919 addr); 920 } 921 } 922 swp_pager_freeswapspace(s_free, n_free); 923 VM_OBJECT_WUNLOCK(object); 924 return (0); 925 } 926 927 /* 928 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 929 * and destroy the source. 930 * 931 * Copy any valid swapblks from the source to the destination. In 932 * cases where both the source and destination have a valid swapblk, 933 * we keep the destination's. 934 * 935 * This routine is allowed to sleep. It may sleep allocating metadata 936 * indirectly through swp_pager_meta_build() or if paging is still in 937 * progress on the source. 938 * 939 * The source object contains no vm_page_t's (which is just as well) 940 * 941 * The source object is of type OBJT_SWAP. 942 * 943 * The source and destination objects must be locked. 944 * Both object locks may temporarily be released. 945 */ 946 void 947 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 948 vm_pindex_t offset, int destroysource) 949 { 950 vm_pindex_t i; 951 daddr_t dstaddr, n_free, s_free, srcaddr; 952 953 VM_OBJECT_ASSERT_WLOCKED(srcobject); 954 VM_OBJECT_ASSERT_WLOCKED(dstobject); 955 956 /* 957 * If destroysource is set, we remove the source object from the 958 * swap_pager internal queue now. 959 */ 960 if (destroysource && srcobject->handle != NULL) { 961 vm_object_pip_add(srcobject, 1); 962 VM_OBJECT_WUNLOCK(srcobject); 963 vm_object_pip_add(dstobject, 1); 964 VM_OBJECT_WUNLOCK(dstobject); 965 sx_xlock(&sw_alloc_sx); 966 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 967 pager_object_list); 968 sx_xunlock(&sw_alloc_sx); 969 VM_OBJECT_WLOCK(dstobject); 970 vm_object_pip_wakeup(dstobject); 971 VM_OBJECT_WLOCK(srcobject); 972 vm_object_pip_wakeup(srcobject); 973 } 974 975 /* 976 * Transfer source to destination. 977 */ 978 swp_pager_init_freerange(&s_free, &n_free); 979 for (i = 0; i < dstobject->size; ++i) { 980 srcaddr = swp_pager_meta_ctl(srcobject, i + offset, SWM_POP); 981 if (srcaddr == SWAPBLK_NONE) 982 continue; 983 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 984 if (dstaddr != SWAPBLK_NONE) { 985 /* 986 * Destination has valid swapblk or it is represented 987 * by a resident page. We destroy the source block. 988 */ 989 swp_pager_update_freerange(&s_free, &n_free, srcaddr); 990 continue; 991 } 992 993 /* 994 * Destination has no swapblk and is not resident, 995 * copy source. 996 * 997 * swp_pager_meta_build() can sleep. 998 */ 999 vm_object_pip_add(srcobject, 1); 1000 VM_OBJECT_WUNLOCK(srcobject); 1001 vm_object_pip_add(dstobject, 1); 1002 dstaddr = swp_pager_meta_build(dstobject, i, srcaddr); 1003 KASSERT(dstaddr == SWAPBLK_NONE, 1004 ("Unexpected destination swapblk")); 1005 vm_object_pip_wakeup(dstobject); 1006 VM_OBJECT_WLOCK(srcobject); 1007 vm_object_pip_wakeup(srcobject); 1008 } 1009 swp_pager_freeswapspace(s_free, n_free); 1010 1011 /* 1012 * Free left over swap blocks in source. 1013 * 1014 * We have to revert the type to OBJT_DEFAULT so we do not accidentally 1015 * double-remove the object from the swap queues. 1016 */ 1017 if (destroysource) { 1018 swp_pager_meta_free_all(srcobject); 1019 /* 1020 * Reverting the type is not necessary, the caller is going 1021 * to destroy srcobject directly, but I'm doing it here 1022 * for consistency since we've removed the object from its 1023 * queues. 1024 */ 1025 srcobject->type = OBJT_DEFAULT; 1026 } 1027 } 1028 1029 /* 1030 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1031 * the requested page. 1032 * 1033 * We determine whether good backing store exists for the requested 1034 * page and return TRUE if it does, FALSE if it doesn't. 1035 * 1036 * If TRUE, we also try to determine how much valid, contiguous backing 1037 * store exists before and after the requested page. 1038 */ 1039 static boolean_t 1040 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1041 int *after) 1042 { 1043 daddr_t blk, blk0; 1044 int i; 1045 1046 VM_OBJECT_ASSERT_LOCKED(object); 1047 1048 /* 1049 * do we have good backing store at the requested index ? 1050 */ 1051 blk0 = swp_pager_meta_ctl(object, pindex, 0); 1052 if (blk0 == SWAPBLK_NONE) { 1053 if (before) 1054 *before = 0; 1055 if (after) 1056 *after = 0; 1057 return (FALSE); 1058 } 1059 1060 /* 1061 * find backwards-looking contiguous good backing store 1062 */ 1063 if (before != NULL) { 1064 for (i = 1; i < SWB_NPAGES; i++) { 1065 if (i > pindex) 1066 break; 1067 blk = swp_pager_meta_ctl(object, pindex - i, 0); 1068 if (blk != blk0 - i) 1069 break; 1070 } 1071 *before = i - 1; 1072 } 1073 1074 /* 1075 * find forward-looking contiguous good backing store 1076 */ 1077 if (after != NULL) { 1078 for (i = 1; i < SWB_NPAGES; i++) { 1079 blk = swp_pager_meta_ctl(object, pindex + i, 0); 1080 if (blk != blk0 + i) 1081 break; 1082 } 1083 *after = i - 1; 1084 } 1085 return (TRUE); 1086 } 1087 1088 /* 1089 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1090 * 1091 * This removes any associated swap backing store, whether valid or 1092 * not, from the page. 1093 * 1094 * This routine is typically called when a page is made dirty, at 1095 * which point any associated swap can be freed. MADV_FREE also 1096 * calls us in a special-case situation 1097 * 1098 * NOTE!!! If the page is clean and the swap was valid, the caller 1099 * should make the page dirty before calling this routine. This routine 1100 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1101 * depends on it. 1102 * 1103 * This routine may not sleep. 1104 * 1105 * The object containing the page must be locked. 1106 */ 1107 static void 1108 swap_pager_unswapped(vm_page_t m) 1109 { 1110 daddr_t srcaddr; 1111 1112 srcaddr = swp_pager_meta_ctl(m->object, m->pindex, SWM_POP); 1113 if (srcaddr != SWAPBLK_NONE) 1114 swp_pager_freeswapspace(srcaddr, 1); 1115 } 1116 1117 /* 1118 * swap_pager_getpages() - bring pages in from swap 1119 * 1120 * Attempt to page in the pages in array "ma" of length "count". The 1121 * caller may optionally specify that additional pages preceding and 1122 * succeeding the specified range be paged in. The number of such pages 1123 * is returned in the "rbehind" and "rahead" parameters, and they will 1124 * be in the inactive queue upon return. 1125 * 1126 * The pages in "ma" must be busied and will remain busied upon return. 1127 */ 1128 static int 1129 swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count, int *rbehind, 1130 int *rahead) 1131 { 1132 struct buf *bp; 1133 vm_page_t bm, mpred, msucc, p; 1134 vm_pindex_t pindex; 1135 daddr_t blk; 1136 int i, maxahead, maxbehind, reqcount; 1137 1138 reqcount = count; 1139 1140 /* 1141 * Determine the final number of read-behind pages and 1142 * allocate them BEFORE releasing the object lock. Otherwise, 1143 * there can be a problematic race with vm_object_split(). 1144 * Specifically, vm_object_split() might first transfer pages 1145 * that precede ma[0] in the current object to a new object, 1146 * and then this function incorrectly recreates those pages as 1147 * read-behind pages in the current object. 1148 */ 1149 if (!swap_pager_haspage(object, ma[0]->pindex, &maxbehind, &maxahead)) 1150 return (VM_PAGER_FAIL); 1151 1152 /* 1153 * Clip the readahead and readbehind ranges to exclude resident pages. 1154 */ 1155 if (rahead != NULL) { 1156 KASSERT(reqcount - 1 <= maxahead, 1157 ("page count %d extends beyond swap block", reqcount)); 1158 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1159 pindex = ma[reqcount - 1]->pindex; 1160 msucc = TAILQ_NEXT(ma[reqcount - 1], listq); 1161 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1162 *rahead = msucc->pindex - pindex - 1; 1163 } 1164 if (rbehind != NULL) { 1165 *rbehind = imin(*rbehind, maxbehind); 1166 pindex = ma[0]->pindex; 1167 mpred = TAILQ_PREV(ma[0], pglist, listq); 1168 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1169 *rbehind = pindex - mpred->pindex - 1; 1170 } 1171 1172 bm = ma[0]; 1173 for (i = 0; i < count; i++) 1174 ma[i]->oflags |= VPO_SWAPINPROG; 1175 1176 /* 1177 * Allocate readahead and readbehind pages. 1178 */ 1179 if (rbehind != NULL) { 1180 for (i = 1; i <= *rbehind; i++) { 1181 p = vm_page_alloc(object, ma[0]->pindex - i, 1182 VM_ALLOC_NORMAL); 1183 if (p == NULL) 1184 break; 1185 p->oflags |= VPO_SWAPINPROG; 1186 bm = p; 1187 } 1188 *rbehind = i - 1; 1189 } 1190 if (rahead != NULL) { 1191 for (i = 0; i < *rahead; i++) { 1192 p = vm_page_alloc(object, 1193 ma[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1194 if (p == NULL) 1195 break; 1196 p->oflags |= VPO_SWAPINPROG; 1197 } 1198 *rahead = i; 1199 } 1200 if (rbehind != NULL) 1201 count += *rbehind; 1202 if (rahead != NULL) 1203 count += *rahead; 1204 1205 vm_object_pip_add(object, count); 1206 1207 pindex = bm->pindex; 1208 blk = swp_pager_meta_ctl(object, pindex, 0); 1209 KASSERT(blk != SWAPBLK_NONE, 1210 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1211 1212 VM_OBJECT_WUNLOCK(object); 1213 bp = uma_zalloc(swrbuf_zone, M_WAITOK); 1214 /* Pages cannot leave the object while busy. */ 1215 for (i = 0, p = bm; i < count; i++, p = TAILQ_NEXT(p, listq)) { 1216 MPASS(p->pindex == bm->pindex + i); 1217 bp->b_pages[i] = p; 1218 } 1219 1220 bp->b_flags |= B_PAGING; 1221 bp->b_iocmd = BIO_READ; 1222 bp->b_iodone = swp_pager_async_iodone; 1223 bp->b_rcred = crhold(thread0.td_ucred); 1224 bp->b_wcred = crhold(thread0.td_ucred); 1225 bp->b_blkno = blk; 1226 bp->b_bcount = PAGE_SIZE * count; 1227 bp->b_bufsize = PAGE_SIZE * count; 1228 bp->b_npages = count; 1229 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1230 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1231 1232 VM_CNT_INC(v_swapin); 1233 VM_CNT_ADD(v_swappgsin, count); 1234 1235 /* 1236 * perform the I/O. NOTE!!! bp cannot be considered valid after 1237 * this point because we automatically release it on completion. 1238 * Instead, we look at the one page we are interested in which we 1239 * still hold a lock on even through the I/O completion. 1240 * 1241 * The other pages in our ma[] array are also released on completion, 1242 * so we cannot assume they are valid anymore either. 1243 * 1244 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1245 */ 1246 BUF_KERNPROC(bp); 1247 swp_pager_strategy(bp); 1248 1249 /* 1250 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1251 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1252 * is set in the metadata for each page in the request. 1253 */ 1254 VM_OBJECT_WLOCK(object); 1255 while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) { 1256 ma[0]->oflags |= VPO_SWAPSLEEP; 1257 VM_CNT_INC(v_intrans); 1258 if (VM_OBJECT_SLEEP(object, &object->paging_in_progress, PSWP, 1259 "swread", hz * 20)) { 1260 printf( 1261 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1262 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1263 } 1264 } 1265 1266 /* 1267 * If we had an unrecoverable read error pages will not be valid. 1268 */ 1269 for (i = 0; i < reqcount; i++) 1270 if (ma[i]->valid != VM_PAGE_BITS_ALL) 1271 return (VM_PAGER_ERROR); 1272 1273 return (VM_PAGER_OK); 1274 1275 /* 1276 * A final note: in a low swap situation, we cannot deallocate swap 1277 * and mark a page dirty here because the caller is likely to mark 1278 * the page clean when we return, causing the page to possibly revert 1279 * to all-zero's later. 1280 */ 1281 } 1282 1283 /* 1284 * swap_pager_getpages_async(): 1285 * 1286 * Right now this is emulation of asynchronous operation on top of 1287 * swap_pager_getpages(). 1288 */ 1289 static int 1290 swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count, 1291 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1292 { 1293 int r, error; 1294 1295 r = swap_pager_getpages(object, ma, count, rbehind, rahead); 1296 VM_OBJECT_WUNLOCK(object); 1297 switch (r) { 1298 case VM_PAGER_OK: 1299 error = 0; 1300 break; 1301 case VM_PAGER_ERROR: 1302 error = EIO; 1303 break; 1304 case VM_PAGER_FAIL: 1305 error = EINVAL; 1306 break; 1307 default: 1308 panic("unhandled swap_pager_getpages() error %d", r); 1309 } 1310 (iodone)(arg, ma, count, error); 1311 VM_OBJECT_WLOCK(object); 1312 1313 return (r); 1314 } 1315 1316 /* 1317 * swap_pager_putpages: 1318 * 1319 * Assign swap (if necessary) and initiate I/O on the specified pages. 1320 * 1321 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1322 * are automatically converted to SWAP objects. 1323 * 1324 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1325 * vm_page reservation system coupled with properly written VFS devices 1326 * should ensure that no low-memory deadlock occurs. This is an area 1327 * which needs work. 1328 * 1329 * The parent has N vm_object_pip_add() references prior to 1330 * calling us and will remove references for rtvals[] that are 1331 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1332 * completion. 1333 * 1334 * The parent has soft-busy'd the pages it passes us and will unbusy 1335 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1336 * We need to unbusy the rest on I/O completion. 1337 */ 1338 static void 1339 swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count, 1340 int flags, int *rtvals) 1341 { 1342 int i, n; 1343 boolean_t sync; 1344 daddr_t addr, n_free, s_free; 1345 1346 swp_pager_init_freerange(&s_free, &n_free); 1347 if (count && ma[0]->object != object) { 1348 panic("swap_pager_putpages: object mismatch %p/%p", 1349 object, 1350 ma[0]->object 1351 ); 1352 } 1353 1354 /* 1355 * Step 1 1356 * 1357 * Turn object into OBJT_SWAP 1358 * check for bogus sysops 1359 * force sync if not pageout process 1360 */ 1361 if (object->type != OBJT_SWAP) { 1362 addr = swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1363 KASSERT(addr == SWAPBLK_NONE, 1364 ("unexpected object swap block")); 1365 } 1366 VM_OBJECT_WUNLOCK(object); 1367 1368 n = 0; 1369 if (curproc != pageproc) 1370 sync = TRUE; 1371 else 1372 sync = (flags & VM_PAGER_PUT_SYNC) != 0; 1373 1374 /* 1375 * Step 2 1376 * 1377 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1378 * The page is left dirty until the pageout operation completes 1379 * successfully. 1380 */ 1381 for (i = 0; i < count; i += n) { 1382 int j; 1383 struct buf *bp; 1384 daddr_t blk; 1385 1386 /* Maximum I/O size is limited by maximum swap block size. */ 1387 n = min(count - i, nsw_cluster_max); 1388 1389 /* Get a block of swap of size up to size n. */ 1390 blk = swp_pager_getswapspace(&n, 4); 1391 if (blk == SWAPBLK_NONE) { 1392 for (j = 0; j < n; ++j) 1393 rtvals[i+j] = VM_PAGER_FAIL; 1394 continue; 1395 } 1396 1397 /* 1398 * All I/O parameters have been satisfied, build the I/O 1399 * request and assign the swap space. 1400 */ 1401 if (sync != TRUE) { 1402 mtx_lock(&swbuf_mtx); 1403 while (nsw_wcount_async == 0) 1404 msleep(&nsw_wcount_async, &swbuf_mtx, PVM, 1405 "swbufa", 0); 1406 nsw_wcount_async--; 1407 mtx_unlock(&swbuf_mtx); 1408 } 1409 bp = uma_zalloc(swwbuf_zone, M_WAITOK); 1410 if (sync != TRUE) 1411 bp->b_flags = B_ASYNC; 1412 bp->b_flags |= B_PAGING; 1413 bp->b_iocmd = BIO_WRITE; 1414 1415 bp->b_rcred = crhold(thread0.td_ucred); 1416 bp->b_wcred = crhold(thread0.td_ucred); 1417 bp->b_bcount = PAGE_SIZE * n; 1418 bp->b_bufsize = PAGE_SIZE * n; 1419 bp->b_blkno = blk; 1420 1421 VM_OBJECT_WLOCK(object); 1422 for (j = 0; j < n; ++j) { 1423 vm_page_t mreq = ma[i+j]; 1424 1425 addr = swp_pager_meta_build(mreq->object, mreq->pindex, 1426 blk + j); 1427 if (addr != SWAPBLK_NONE) 1428 swp_pager_update_freerange(&s_free, &n_free, 1429 addr); 1430 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1431 mreq->oflags |= VPO_SWAPINPROG; 1432 bp->b_pages[j] = mreq; 1433 } 1434 VM_OBJECT_WUNLOCK(object); 1435 bp->b_npages = n; 1436 /* 1437 * Must set dirty range for NFS to work. 1438 */ 1439 bp->b_dirtyoff = 0; 1440 bp->b_dirtyend = bp->b_bcount; 1441 1442 VM_CNT_INC(v_swapout); 1443 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1444 1445 /* 1446 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1447 * can call the async completion routine at the end of a 1448 * synchronous I/O operation. Otherwise, our caller would 1449 * perform duplicate unbusy and wakeup operations on the page 1450 * and object, respectively. 1451 */ 1452 for (j = 0; j < n; j++) 1453 rtvals[i + j] = VM_PAGER_PEND; 1454 1455 /* 1456 * asynchronous 1457 * 1458 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1459 */ 1460 if (sync == FALSE) { 1461 bp->b_iodone = swp_pager_async_iodone; 1462 BUF_KERNPROC(bp); 1463 swp_pager_strategy(bp); 1464 continue; 1465 } 1466 1467 /* 1468 * synchronous 1469 * 1470 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1471 */ 1472 bp->b_iodone = bdone; 1473 swp_pager_strategy(bp); 1474 1475 /* 1476 * Wait for the sync I/O to complete. 1477 */ 1478 bwait(bp, PVM, "swwrt"); 1479 1480 /* 1481 * Now that we are through with the bp, we can call the 1482 * normal async completion, which frees everything up. 1483 */ 1484 swp_pager_async_iodone(bp); 1485 } 1486 VM_OBJECT_WLOCK(object); 1487 swp_pager_freeswapspace(s_free, n_free); 1488 } 1489 1490 /* 1491 * swp_pager_async_iodone: 1492 * 1493 * Completion routine for asynchronous reads and writes from/to swap. 1494 * Also called manually by synchronous code to finish up a bp. 1495 * 1496 * This routine may not sleep. 1497 */ 1498 static void 1499 swp_pager_async_iodone(struct buf *bp) 1500 { 1501 int i; 1502 vm_object_t object = NULL; 1503 1504 /* 1505 * Report error - unless we ran out of memory, in which case 1506 * we've already logged it in swapgeom_strategy(). 1507 */ 1508 if (bp->b_ioflags & BIO_ERROR && bp->b_error != ENOMEM) { 1509 printf( 1510 "swap_pager: I/O error - %s failed; blkno %ld," 1511 "size %ld, error %d\n", 1512 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1513 (long)bp->b_blkno, 1514 (long)bp->b_bcount, 1515 bp->b_error 1516 ); 1517 } 1518 1519 /* 1520 * remove the mapping for kernel virtual 1521 */ 1522 if (buf_mapped(bp)) 1523 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1524 else 1525 bp->b_data = bp->b_kvabase; 1526 1527 if (bp->b_npages) { 1528 object = bp->b_pages[0]->object; 1529 VM_OBJECT_WLOCK(object); 1530 } 1531 1532 /* 1533 * cleanup pages. If an error occurs writing to swap, we are in 1534 * very serious trouble. If it happens to be a disk error, though, 1535 * we may be able to recover by reassigning the swap later on. So 1536 * in this case we remove the m->swapblk assignment for the page 1537 * but do not free it in the rlist. The errornous block(s) are thus 1538 * never reallocated as swap. Redirty the page and continue. 1539 */ 1540 for (i = 0; i < bp->b_npages; ++i) { 1541 vm_page_t m = bp->b_pages[i]; 1542 1543 m->oflags &= ~VPO_SWAPINPROG; 1544 if (m->oflags & VPO_SWAPSLEEP) { 1545 m->oflags &= ~VPO_SWAPSLEEP; 1546 wakeup(&object->paging_in_progress); 1547 } 1548 1549 if (bp->b_ioflags & BIO_ERROR) { 1550 /* 1551 * If an error occurs I'd love to throw the swapblk 1552 * away without freeing it back to swapspace, so it 1553 * can never be used again. But I can't from an 1554 * interrupt. 1555 */ 1556 if (bp->b_iocmd == BIO_READ) { 1557 /* 1558 * NOTE: for reads, m->dirty will probably 1559 * be overridden by the original caller of 1560 * getpages so don't play cute tricks here. 1561 */ 1562 m->valid = 0; 1563 } else { 1564 /* 1565 * If a write error occurs, reactivate page 1566 * so it doesn't clog the inactive list, 1567 * then finish the I/O. 1568 */ 1569 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1570 vm_page_lock(m); 1571 vm_page_activate(m); 1572 vm_page_unlock(m); 1573 vm_page_sunbusy(m); 1574 } 1575 } else if (bp->b_iocmd == BIO_READ) { 1576 /* 1577 * NOTE: for reads, m->dirty will probably be 1578 * overridden by the original caller of getpages so 1579 * we cannot set them in order to free the underlying 1580 * swap in a low-swap situation. I don't think we'd 1581 * want to do that anyway, but it was an optimization 1582 * that existed in the old swapper for a time before 1583 * it got ripped out due to precisely this problem. 1584 */ 1585 KASSERT(!pmap_page_is_mapped(m), 1586 ("swp_pager_async_iodone: page %p is mapped", m)); 1587 KASSERT(m->dirty == 0, 1588 ("swp_pager_async_iodone: page %p is dirty", m)); 1589 1590 m->valid = VM_PAGE_BITS_ALL; 1591 if (i < bp->b_pgbefore || 1592 i >= bp->b_npages - bp->b_pgafter) 1593 vm_page_readahead_finish(m); 1594 } else { 1595 /* 1596 * For write success, clear the dirty 1597 * status, then finish the I/O ( which decrements the 1598 * busy count and possibly wakes waiter's up ). 1599 * A page is only written to swap after a period of 1600 * inactivity. Therefore, we do not expect it to be 1601 * reused. 1602 */ 1603 KASSERT(!pmap_page_is_write_mapped(m), 1604 ("swp_pager_async_iodone: page %p is not write" 1605 " protected", m)); 1606 vm_page_undirty(m); 1607 vm_page_lock(m); 1608 vm_page_deactivate_noreuse(m); 1609 vm_page_unlock(m); 1610 vm_page_sunbusy(m); 1611 } 1612 } 1613 1614 /* 1615 * adjust pip. NOTE: the original parent may still have its own 1616 * pip refs on the object. 1617 */ 1618 if (object != NULL) { 1619 vm_object_pip_wakeupn(object, bp->b_npages); 1620 VM_OBJECT_WUNLOCK(object); 1621 } 1622 1623 /* 1624 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1625 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1626 * trigger a KASSERT in relpbuf(). 1627 */ 1628 if (bp->b_vp) { 1629 bp->b_vp = NULL; 1630 bp->b_bufobj = NULL; 1631 } 1632 /* 1633 * release the physical I/O buffer 1634 */ 1635 if (bp->b_flags & B_ASYNC) { 1636 mtx_lock(&swbuf_mtx); 1637 if (++nsw_wcount_async == 1) 1638 wakeup(&nsw_wcount_async); 1639 mtx_unlock(&swbuf_mtx); 1640 } 1641 uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp); 1642 } 1643 1644 int 1645 swap_pager_nswapdev(void) 1646 { 1647 1648 return (nswapdev); 1649 } 1650 1651 static void 1652 swp_pager_force_dirty(vm_page_t m) 1653 { 1654 1655 vm_page_dirty(m); 1656 #ifdef INVARIANTS 1657 vm_page_lock(m); 1658 if (!vm_page_wired(m) && m->queue == PQ_NONE) 1659 panic("page %p is neither wired nor queued", m); 1660 vm_page_unlock(m); 1661 #endif 1662 vm_page_xunbusy(m); 1663 swap_pager_unswapped(m); 1664 } 1665 1666 static void 1667 swp_pager_force_launder(vm_page_t m) 1668 { 1669 1670 vm_page_dirty(m); 1671 vm_page_lock(m); 1672 vm_page_launder(m); 1673 vm_page_unlock(m); 1674 vm_page_xunbusy(m); 1675 swap_pager_unswapped(m); 1676 } 1677 1678 /* 1679 * SWP_PAGER_FORCE_PAGEIN() - force swap blocks to be paged in 1680 * 1681 * This routine dissociates pages starting at the given index within an 1682 * object from their backing store, paging them in if they do not reside 1683 * in memory. Pages that are paged in are marked dirty and placed in the 1684 * laundry queue. Pages are marked dirty because they no longer have 1685 * backing store. They are placed in the laundry queue because they have 1686 * not been accessed recently. Otherwise, they would already reside in 1687 * memory. 1688 */ 1689 static void 1690 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex, int npages) 1691 { 1692 vm_page_t ma[npages]; 1693 int i, j; 1694 1695 KASSERT(npages > 0, ("%s: No pages", __func__)); 1696 KASSERT(npages <= MAXPHYS / PAGE_SIZE, 1697 ("%s: Too many pages: %d", __func__, npages)); 1698 vm_object_pip_add(object, npages); 1699 vm_page_grab_pages(object, pindex, VM_ALLOC_NORMAL, ma, npages); 1700 for (i = j = 0;; i++) { 1701 /* Count nonresident pages, to page-in all at once. */ 1702 if (i < npages && ma[i]->valid != VM_PAGE_BITS_ALL) 1703 continue; 1704 if (j < i) { 1705 /* Page-in nonresident pages. Mark for laundering. */ 1706 if (swap_pager_getpages(object, &ma[j], i - j, NULL, 1707 NULL) != VM_PAGER_OK) 1708 panic("%s: read from swap failed", __func__); 1709 do { 1710 swp_pager_force_launder(ma[j]); 1711 } while (++j < i); 1712 } 1713 if (i == npages) 1714 break; 1715 /* Mark dirty a resident page. */ 1716 swp_pager_force_dirty(ma[j++]); 1717 } 1718 vm_object_pip_wakeupn(object, npages); 1719 } 1720 1721 /* 1722 * swap_pager_swapoff_object: 1723 * 1724 * Page in all of the pages that have been paged out for an object 1725 * to a swap device. 1726 */ 1727 static void 1728 swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object) 1729 { 1730 struct swblk *sb; 1731 vm_pindex_t pi, s_pindex; 1732 daddr_t blk, n_blks, s_blk; 1733 int i; 1734 1735 n_blks = 0; 1736 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1737 &object->un_pager.swp.swp_blks, pi)) != NULL; ) { 1738 for (i = 0; i < SWAP_META_PAGES; i++) { 1739 blk = sb->d[i]; 1740 if (!swp_pager_isondev(blk, sp)) 1741 blk = SWAPBLK_NONE; 1742 1743 /* 1744 * If there are no blocks/pages accumulated, start a new 1745 * accumulation here. 1746 */ 1747 if (n_blks == 0) { 1748 if (blk != SWAPBLK_NONE) { 1749 s_blk = blk; 1750 s_pindex = sb->p + i; 1751 n_blks = 1; 1752 } 1753 continue; 1754 } 1755 1756 /* 1757 * If the accumulation can be extended without breaking 1758 * the sequence of consecutive blocks and pages that 1759 * swp_pager_force_pagein() depends on, do so. 1760 */ 1761 if (n_blks < MAXPHYS / PAGE_SIZE && 1762 s_blk + n_blks == blk && 1763 s_pindex + n_blks == sb->p + i) { 1764 ++n_blks; 1765 continue; 1766 } 1767 1768 /* 1769 * The sequence of consecutive blocks and pages cannot 1770 * be extended, so page them all in here. Then, 1771 * because doing so involves releasing and reacquiring 1772 * a lock that protects the swap block pctrie, do not 1773 * rely on the current swap block. Break this loop and 1774 * re-fetch the same pindex from the pctrie again. 1775 */ 1776 swp_pager_force_pagein(object, s_pindex, n_blks); 1777 n_blks = 0; 1778 break; 1779 } 1780 if (i == SWAP_META_PAGES) 1781 pi = sb->p + SWAP_META_PAGES; 1782 } 1783 if (n_blks > 0) 1784 swp_pager_force_pagein(object, s_pindex, n_blks); 1785 } 1786 1787 /* 1788 * swap_pager_swapoff: 1789 * 1790 * Page in all of the pages that have been paged out to the 1791 * given device. The corresponding blocks in the bitmap must be 1792 * marked as allocated and the device must be flagged SW_CLOSING. 1793 * There may be no processes swapped out to the device. 1794 * 1795 * This routine may block. 1796 */ 1797 static void 1798 swap_pager_swapoff(struct swdevt *sp) 1799 { 1800 vm_object_t object; 1801 int retries; 1802 1803 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 1804 1805 retries = 0; 1806 full_rescan: 1807 mtx_lock(&vm_object_list_mtx); 1808 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1809 if (object->type != OBJT_SWAP) 1810 continue; 1811 mtx_unlock(&vm_object_list_mtx); 1812 /* Depends on type-stability. */ 1813 VM_OBJECT_WLOCK(object); 1814 1815 /* 1816 * Dead objects are eventually terminated on their own. 1817 */ 1818 if ((object->flags & OBJ_DEAD) != 0) 1819 goto next_obj; 1820 1821 /* 1822 * Sync with fences placed after pctrie 1823 * initialization. We must not access pctrie below 1824 * unless we checked that our object is swap and not 1825 * dead. 1826 */ 1827 atomic_thread_fence_acq(); 1828 if (object->type != OBJT_SWAP) 1829 goto next_obj; 1830 1831 swap_pager_swapoff_object(sp, object); 1832 next_obj: 1833 VM_OBJECT_WUNLOCK(object); 1834 mtx_lock(&vm_object_list_mtx); 1835 } 1836 mtx_unlock(&vm_object_list_mtx); 1837 1838 if (sp->sw_used) { 1839 /* 1840 * Objects may be locked or paging to the device being 1841 * removed, so we will miss their pages and need to 1842 * make another pass. We have marked this device as 1843 * SW_CLOSING, so the activity should finish soon. 1844 */ 1845 retries++; 1846 if (retries > 100) { 1847 panic("swapoff: failed to locate %d swap blocks", 1848 sp->sw_used); 1849 } 1850 pause("swpoff", hz / 20); 1851 goto full_rescan; 1852 } 1853 EVENTHANDLER_INVOKE(swapoff, sp); 1854 } 1855 1856 /************************************************************************ 1857 * SWAP META DATA * 1858 ************************************************************************ 1859 * 1860 * These routines manipulate the swap metadata stored in the 1861 * OBJT_SWAP object. 1862 * 1863 * Swap metadata is implemented with a global hash and not directly 1864 * linked into the object. Instead the object simply contains 1865 * appropriate tracking counters. 1866 */ 1867 1868 /* 1869 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? 1870 */ 1871 static bool 1872 swp_pager_swblk_empty(struct swblk *sb, int start, int limit) 1873 { 1874 int i; 1875 1876 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); 1877 for (i = start; i < limit; i++) { 1878 if (sb->d[i] != SWAPBLK_NONE) 1879 return (false); 1880 } 1881 return (true); 1882 } 1883 1884 /* 1885 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1886 * 1887 * We first convert the object to a swap object if it is a default 1888 * object. 1889 * 1890 * The specified swapblk is added to the object's swap metadata. If 1891 * the swapblk is not valid, it is freed instead. Any previously 1892 * assigned swapblk is returned. 1893 */ 1894 static daddr_t 1895 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1896 { 1897 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 1898 struct swblk *sb, *sb1; 1899 vm_pindex_t modpi, rdpi; 1900 daddr_t prev_swapblk; 1901 int error, i; 1902 1903 VM_OBJECT_ASSERT_WLOCKED(object); 1904 1905 /* 1906 * Convert default object to swap object if necessary 1907 */ 1908 if (object->type != OBJT_SWAP) { 1909 pctrie_init(&object->un_pager.swp.swp_blks); 1910 1911 /* 1912 * Ensure that swap_pager_swapoff()'s iteration over 1913 * object_list does not see a garbage pctrie. 1914 */ 1915 atomic_thread_fence_rel(); 1916 1917 object->type = OBJT_SWAP; 1918 KASSERT(object->handle == NULL, ("default pager with handle")); 1919 } 1920 1921 rdpi = rounddown(pindex, SWAP_META_PAGES); 1922 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi); 1923 if (sb == NULL) { 1924 if (swapblk == SWAPBLK_NONE) 1925 return (SWAPBLK_NONE); 1926 for (;;) { 1927 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 1928 pageproc ? M_USE_RESERVE : 0)); 1929 if (sb != NULL) { 1930 sb->p = rdpi; 1931 for (i = 0; i < SWAP_META_PAGES; i++) 1932 sb->d[i] = SWAPBLK_NONE; 1933 if (atomic_cmpset_int(&swblk_zone_exhausted, 1934 1, 0)) 1935 printf("swblk zone ok\n"); 1936 break; 1937 } 1938 VM_OBJECT_WUNLOCK(object); 1939 if (uma_zone_exhausted(swblk_zone)) { 1940 if (atomic_cmpset_int(&swblk_zone_exhausted, 1941 0, 1)) 1942 printf("swap blk zone exhausted, " 1943 "increase kern.maxswzone\n"); 1944 vm_pageout_oom(VM_OOM_SWAPZ); 1945 pause("swzonxb", 10); 1946 } else 1947 uma_zwait(swblk_zone); 1948 VM_OBJECT_WLOCK(object); 1949 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 1950 rdpi); 1951 if (sb != NULL) 1952 /* 1953 * Somebody swapped out a nearby page, 1954 * allocating swblk at the rdpi index, 1955 * while we dropped the object lock. 1956 */ 1957 goto allocated; 1958 } 1959 for (;;) { 1960 error = SWAP_PCTRIE_INSERT( 1961 &object->un_pager.swp.swp_blks, sb); 1962 if (error == 0) { 1963 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1964 1, 0)) 1965 printf("swpctrie zone ok\n"); 1966 break; 1967 } 1968 VM_OBJECT_WUNLOCK(object); 1969 if (uma_zone_exhausted(swpctrie_zone)) { 1970 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1971 0, 1)) 1972 printf("swap pctrie zone exhausted, " 1973 "increase kern.maxswzone\n"); 1974 vm_pageout_oom(VM_OOM_SWAPZ); 1975 pause("swzonxp", 10); 1976 } else 1977 uma_zwait(swpctrie_zone); 1978 VM_OBJECT_WLOCK(object); 1979 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 1980 rdpi); 1981 if (sb1 != NULL) { 1982 uma_zfree(swblk_zone, sb); 1983 sb = sb1; 1984 goto allocated; 1985 } 1986 } 1987 } 1988 allocated: 1989 MPASS(sb->p == rdpi); 1990 1991 modpi = pindex % SWAP_META_PAGES; 1992 /* Return prior contents of metadata. */ 1993 prev_swapblk = sb->d[modpi]; 1994 /* Enter block into metadata. */ 1995 sb->d[modpi] = swapblk; 1996 1997 /* 1998 * Free the swblk if we end up with the empty page run. 1999 */ 2000 if (swapblk == SWAPBLK_NONE && 2001 swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 2002 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, rdpi); 2003 uma_zfree(swblk_zone, sb); 2004 } 2005 return (prev_swapblk); 2006 } 2007 2008 /* 2009 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2010 * 2011 * The requested range of blocks is freed, with any associated swap 2012 * returned to the swap bitmap. 2013 * 2014 * This routine will free swap metadata structures as they are cleaned 2015 * out. This routine does *NOT* operate on swap metadata associated 2016 * with resident pages. 2017 */ 2018 static void 2019 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count) 2020 { 2021 struct swblk *sb; 2022 daddr_t n_free, s_free; 2023 vm_pindex_t last; 2024 int i, limit, start; 2025 2026 VM_OBJECT_ASSERT_WLOCKED(object); 2027 if (object->type != OBJT_SWAP || count == 0) 2028 return; 2029 2030 swp_pager_init_freerange(&s_free, &n_free); 2031 last = pindex + count; 2032 for (;;) { 2033 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2034 rounddown(pindex, SWAP_META_PAGES)); 2035 if (sb == NULL || sb->p >= last) 2036 break; 2037 start = pindex > sb->p ? pindex - sb->p : 0; 2038 limit = last - sb->p < SWAP_META_PAGES ? last - sb->p : 2039 SWAP_META_PAGES; 2040 for (i = start; i < limit; i++) { 2041 if (sb->d[i] == SWAPBLK_NONE) 2042 continue; 2043 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]); 2044 sb->d[i] = SWAPBLK_NONE; 2045 } 2046 pindex = sb->p + SWAP_META_PAGES; 2047 if (swp_pager_swblk_empty(sb, 0, start) && 2048 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2049 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, 2050 sb->p); 2051 uma_zfree(swblk_zone, sb); 2052 } 2053 } 2054 swp_pager_freeswapspace(s_free, n_free); 2055 } 2056 2057 /* 2058 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2059 * 2060 * This routine locates and destroys all swap metadata associated with 2061 * an object. 2062 */ 2063 static void 2064 swp_pager_meta_free_all(vm_object_t object) 2065 { 2066 struct swblk *sb; 2067 daddr_t n_free, s_free; 2068 vm_pindex_t pindex; 2069 int i; 2070 2071 VM_OBJECT_ASSERT_WLOCKED(object); 2072 if (object->type != OBJT_SWAP) 2073 return; 2074 2075 swp_pager_init_freerange(&s_free, &n_free); 2076 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 2077 &object->un_pager.swp.swp_blks, pindex)) != NULL;) { 2078 pindex = sb->p + SWAP_META_PAGES; 2079 for (i = 0; i < SWAP_META_PAGES; i++) { 2080 if (sb->d[i] == SWAPBLK_NONE) 2081 continue; 2082 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]); 2083 } 2084 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 2085 uma_zfree(swblk_zone, sb); 2086 } 2087 swp_pager_freeswapspace(s_free, n_free); 2088 } 2089 2090 /* 2091 * SWP_PAGER_METACTL() - misc control of swap meta data. 2092 * 2093 * This routine is capable of looking up, or removing swapblk 2094 * assignments in the swap meta data. It returns the swapblk being 2095 * looked-up, popped, or SWAPBLK_NONE if the block was invalid. 2096 * 2097 * When acting on a busy resident page and paging is in progress, we 2098 * have to wait until paging is complete but otherwise can act on the 2099 * busy page. 2100 * 2101 * SWM_POP remove from meta data but do not free it 2102 */ 2103 static daddr_t 2104 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags) 2105 { 2106 struct swblk *sb; 2107 daddr_t r1; 2108 2109 if ((flags & SWM_POP) != 0) 2110 VM_OBJECT_ASSERT_WLOCKED(object); 2111 else 2112 VM_OBJECT_ASSERT_LOCKED(object); 2113 2114 /* 2115 * The meta data only exists if the object is OBJT_SWAP 2116 * and even then might not be allocated yet. 2117 */ 2118 if (object->type != OBJT_SWAP) 2119 return (SWAPBLK_NONE); 2120 2121 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2122 rounddown(pindex, SWAP_META_PAGES)); 2123 if (sb == NULL) 2124 return (SWAPBLK_NONE); 2125 r1 = sb->d[pindex % SWAP_META_PAGES]; 2126 if (r1 == SWAPBLK_NONE) 2127 return (SWAPBLK_NONE); 2128 if ((flags & SWM_POP) != 0) { 2129 sb->d[pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 2130 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 2131 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, 2132 rounddown(pindex, SWAP_META_PAGES)); 2133 uma_zfree(swblk_zone, sb); 2134 } 2135 } 2136 return (r1); 2137 } 2138 2139 /* 2140 * Returns the least page index which is greater than or equal to the 2141 * parameter pindex and for which there is a swap block allocated. 2142 * Returns object's size if the object's type is not swap or if there 2143 * are no allocated swap blocks for the object after the requested 2144 * pindex. 2145 */ 2146 vm_pindex_t 2147 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2148 { 2149 struct swblk *sb; 2150 int i; 2151 2152 VM_OBJECT_ASSERT_LOCKED(object); 2153 if (object->type != OBJT_SWAP) 2154 return (object->size); 2155 2156 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2157 rounddown(pindex, SWAP_META_PAGES)); 2158 if (sb == NULL) 2159 return (object->size); 2160 if (sb->p < pindex) { 2161 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2162 if (sb->d[i] != SWAPBLK_NONE) 2163 return (sb->p + i); 2164 } 2165 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2166 roundup(pindex, SWAP_META_PAGES)); 2167 if (sb == NULL) 2168 return (object->size); 2169 } 2170 for (i = 0; i < SWAP_META_PAGES; i++) { 2171 if (sb->d[i] != SWAPBLK_NONE) 2172 return (sb->p + i); 2173 } 2174 2175 /* 2176 * We get here if a swblk is present in the trie but it 2177 * doesn't map any blocks. 2178 */ 2179 MPASS(0); 2180 return (object->size); 2181 } 2182 2183 /* 2184 * System call swapon(name) enables swapping on device name, 2185 * which must be in the swdevsw. Return EBUSY 2186 * if already swapping on this device. 2187 */ 2188 #ifndef _SYS_SYSPROTO_H_ 2189 struct swapon_args { 2190 char *name; 2191 }; 2192 #endif 2193 2194 /* 2195 * MPSAFE 2196 */ 2197 /* ARGSUSED */ 2198 int 2199 sys_swapon(struct thread *td, struct swapon_args *uap) 2200 { 2201 struct vattr attr; 2202 struct vnode *vp; 2203 struct nameidata nd; 2204 int error; 2205 2206 error = priv_check(td, PRIV_SWAPON); 2207 if (error) 2208 return (error); 2209 2210 sx_xlock(&swdev_syscall_lock); 2211 2212 /* 2213 * Swap metadata may not fit in the KVM if we have physical 2214 * memory of >1GB. 2215 */ 2216 if (swblk_zone == NULL) { 2217 error = ENOMEM; 2218 goto done; 2219 } 2220 2221 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2222 uap->name, td); 2223 error = namei(&nd); 2224 if (error) 2225 goto done; 2226 2227 NDFREE(&nd, NDF_ONLY_PNBUF); 2228 vp = nd.ni_vp; 2229 2230 if (vn_isdisk(vp, &error)) { 2231 error = swapongeom(vp); 2232 } else if (vp->v_type == VREG && 2233 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2234 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2235 /* 2236 * Allow direct swapping to NFS regular files in the same 2237 * way that nfs_mountroot() sets up diskless swapping. 2238 */ 2239 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2240 } 2241 2242 if (error) 2243 vrele(vp); 2244 done: 2245 sx_xunlock(&swdev_syscall_lock); 2246 return (error); 2247 } 2248 2249 /* 2250 * Check that the total amount of swap currently configured does not 2251 * exceed half the theoretical maximum. If it does, print a warning 2252 * message. 2253 */ 2254 static void 2255 swapon_check_swzone(void) 2256 { 2257 unsigned long maxpages, npages; 2258 2259 npages = swap_total; 2260 /* absolute maximum we can handle assuming 100% efficiency */ 2261 maxpages = uma_zone_get_max(swblk_zone) * SWAP_META_PAGES; 2262 2263 /* recommend using no more than half that amount */ 2264 if (npages > maxpages / 2) { 2265 printf("warning: total configured swap (%lu pages) " 2266 "exceeds maximum recommended amount (%lu pages).\n", 2267 npages, maxpages / 2); 2268 printf("warning: increase kern.maxswzone " 2269 "or reduce amount of swap.\n"); 2270 } 2271 } 2272 2273 static void 2274 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2275 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2276 { 2277 struct swdevt *sp, *tsp; 2278 swblk_t dvbase; 2279 u_long mblocks; 2280 2281 /* 2282 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2283 * First chop nblks off to page-align it, then convert. 2284 * 2285 * sw->sw_nblks is in page-sized chunks now too. 2286 */ 2287 nblks &= ~(ctodb(1) - 1); 2288 nblks = dbtoc(nblks); 2289 2290 /* 2291 * If we go beyond this, we get overflows in the radix 2292 * tree bitmap code. 2293 */ 2294 mblocks = 0x40000000 / BLIST_META_RADIX; 2295 if (nblks > mblocks) { 2296 printf( 2297 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2298 mblocks / 1024 / 1024 * PAGE_SIZE); 2299 nblks = mblocks; 2300 } 2301 2302 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2303 sp->sw_vp = vp; 2304 sp->sw_id = id; 2305 sp->sw_dev = dev; 2306 sp->sw_nblks = nblks; 2307 sp->sw_used = 0; 2308 sp->sw_strategy = strategy; 2309 sp->sw_close = close; 2310 sp->sw_flags = flags; 2311 2312 sp->sw_blist = blist_create(nblks, M_WAITOK); 2313 /* 2314 * Do not free the first two block in order to avoid overwriting 2315 * any bsd label at the front of the partition 2316 */ 2317 blist_free(sp->sw_blist, 2, nblks - 2); 2318 2319 dvbase = 0; 2320 mtx_lock(&sw_dev_mtx); 2321 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2322 if (tsp->sw_end >= dvbase) { 2323 /* 2324 * We put one uncovered page between the devices 2325 * in order to definitively prevent any cross-device 2326 * I/O requests 2327 */ 2328 dvbase = tsp->sw_end + 1; 2329 } 2330 } 2331 sp->sw_first = dvbase; 2332 sp->sw_end = dvbase + nblks; 2333 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2334 nswapdev++; 2335 swap_pager_avail += nblks - 2; 2336 swap_total += nblks; 2337 swapon_check_swzone(); 2338 swp_sizecheck(); 2339 mtx_unlock(&sw_dev_mtx); 2340 EVENTHANDLER_INVOKE(swapon, sp); 2341 } 2342 2343 /* 2344 * SYSCALL: swapoff(devname) 2345 * 2346 * Disable swapping on the given device. 2347 * 2348 * XXX: Badly designed system call: it should use a device index 2349 * rather than filename as specification. We keep sw_vp around 2350 * only to make this work. 2351 */ 2352 #ifndef _SYS_SYSPROTO_H_ 2353 struct swapoff_args { 2354 char *name; 2355 }; 2356 #endif 2357 2358 /* 2359 * MPSAFE 2360 */ 2361 /* ARGSUSED */ 2362 int 2363 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2364 { 2365 struct vnode *vp; 2366 struct nameidata nd; 2367 struct swdevt *sp; 2368 int error; 2369 2370 error = priv_check(td, PRIV_SWAPOFF); 2371 if (error) 2372 return (error); 2373 2374 sx_xlock(&swdev_syscall_lock); 2375 2376 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2377 td); 2378 error = namei(&nd); 2379 if (error) 2380 goto done; 2381 NDFREE(&nd, NDF_ONLY_PNBUF); 2382 vp = nd.ni_vp; 2383 2384 mtx_lock(&sw_dev_mtx); 2385 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2386 if (sp->sw_vp == vp) 2387 break; 2388 } 2389 mtx_unlock(&sw_dev_mtx); 2390 if (sp == NULL) { 2391 error = EINVAL; 2392 goto done; 2393 } 2394 error = swapoff_one(sp, td->td_ucred); 2395 done: 2396 sx_xunlock(&swdev_syscall_lock); 2397 return (error); 2398 } 2399 2400 static int 2401 swapoff_one(struct swdevt *sp, struct ucred *cred) 2402 { 2403 u_long nblks; 2404 #ifdef MAC 2405 int error; 2406 #endif 2407 2408 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2409 #ifdef MAC 2410 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2411 error = mac_system_check_swapoff(cred, sp->sw_vp); 2412 (void) VOP_UNLOCK(sp->sw_vp, 0); 2413 if (error != 0) 2414 return (error); 2415 #endif 2416 nblks = sp->sw_nblks; 2417 2418 /* 2419 * We can turn off this swap device safely only if the 2420 * available virtual memory in the system will fit the amount 2421 * of data we will have to page back in, plus an epsilon so 2422 * the system doesn't become critically low on swap space. 2423 */ 2424 if (vm_free_count() + swap_pager_avail < nblks + nswap_lowat) 2425 return (ENOMEM); 2426 2427 /* 2428 * Prevent further allocations on this device. 2429 */ 2430 mtx_lock(&sw_dev_mtx); 2431 sp->sw_flags |= SW_CLOSING; 2432 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2433 swap_total -= nblks; 2434 mtx_unlock(&sw_dev_mtx); 2435 2436 /* 2437 * Page in the contents of the device and close it. 2438 */ 2439 swap_pager_swapoff(sp); 2440 2441 sp->sw_close(curthread, sp); 2442 mtx_lock(&sw_dev_mtx); 2443 sp->sw_id = NULL; 2444 TAILQ_REMOVE(&swtailq, sp, sw_list); 2445 nswapdev--; 2446 if (nswapdev == 0) { 2447 swap_pager_full = 2; 2448 swap_pager_almost_full = 1; 2449 } 2450 if (swdevhd == sp) 2451 swdevhd = NULL; 2452 mtx_unlock(&sw_dev_mtx); 2453 blist_destroy(sp->sw_blist); 2454 free(sp, M_VMPGDATA); 2455 return (0); 2456 } 2457 2458 void 2459 swapoff_all(void) 2460 { 2461 struct swdevt *sp, *spt; 2462 const char *devname; 2463 int error; 2464 2465 sx_xlock(&swdev_syscall_lock); 2466 2467 mtx_lock(&sw_dev_mtx); 2468 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2469 mtx_unlock(&sw_dev_mtx); 2470 if (vn_isdisk(sp->sw_vp, NULL)) 2471 devname = devtoname(sp->sw_vp->v_rdev); 2472 else 2473 devname = "[file]"; 2474 error = swapoff_one(sp, thread0.td_ucred); 2475 if (error != 0) { 2476 printf("Cannot remove swap device %s (error=%d), " 2477 "skipping.\n", devname, error); 2478 } else if (bootverbose) { 2479 printf("Swap device %s removed.\n", devname); 2480 } 2481 mtx_lock(&sw_dev_mtx); 2482 } 2483 mtx_unlock(&sw_dev_mtx); 2484 2485 sx_xunlock(&swdev_syscall_lock); 2486 } 2487 2488 void 2489 swap_pager_status(int *total, int *used) 2490 { 2491 struct swdevt *sp; 2492 2493 *total = 0; 2494 *used = 0; 2495 mtx_lock(&sw_dev_mtx); 2496 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2497 *total += sp->sw_nblks; 2498 *used += sp->sw_used; 2499 } 2500 mtx_unlock(&sw_dev_mtx); 2501 } 2502 2503 int 2504 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2505 { 2506 struct swdevt *sp; 2507 const char *tmp_devname; 2508 int error, n; 2509 2510 n = 0; 2511 error = ENOENT; 2512 mtx_lock(&sw_dev_mtx); 2513 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2514 if (n != name) { 2515 n++; 2516 continue; 2517 } 2518 xs->xsw_version = XSWDEV_VERSION; 2519 xs->xsw_dev = sp->sw_dev; 2520 xs->xsw_flags = sp->sw_flags; 2521 xs->xsw_nblks = sp->sw_nblks; 2522 xs->xsw_used = sp->sw_used; 2523 if (devname != NULL) { 2524 if (vn_isdisk(sp->sw_vp, NULL)) 2525 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2526 else 2527 tmp_devname = "[file]"; 2528 strncpy(devname, tmp_devname, len); 2529 } 2530 error = 0; 2531 break; 2532 } 2533 mtx_unlock(&sw_dev_mtx); 2534 return (error); 2535 } 2536 2537 #if defined(COMPAT_FREEBSD11) 2538 #define XSWDEV_VERSION_11 1 2539 struct xswdev11 { 2540 u_int xsw_version; 2541 uint32_t xsw_dev; 2542 int xsw_flags; 2543 int xsw_nblks; 2544 int xsw_used; 2545 }; 2546 #endif 2547 2548 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2549 struct xswdev32 { 2550 u_int xsw_version; 2551 u_int xsw_dev1, xsw_dev2; 2552 int xsw_flags; 2553 int xsw_nblks; 2554 int xsw_used; 2555 }; 2556 #endif 2557 2558 static int 2559 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2560 { 2561 struct xswdev xs; 2562 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2563 struct xswdev32 xs32; 2564 #endif 2565 #if defined(COMPAT_FREEBSD11) 2566 struct xswdev11 xs11; 2567 #endif 2568 int error; 2569 2570 if (arg2 != 1) /* name length */ 2571 return (EINVAL); 2572 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2573 if (error != 0) 2574 return (error); 2575 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2576 if (req->oldlen == sizeof(xs32)) { 2577 xs32.xsw_version = XSWDEV_VERSION; 2578 xs32.xsw_dev1 = xs.xsw_dev; 2579 xs32.xsw_dev2 = xs.xsw_dev >> 32; 2580 xs32.xsw_flags = xs.xsw_flags; 2581 xs32.xsw_nblks = xs.xsw_nblks; 2582 xs32.xsw_used = xs.xsw_used; 2583 error = SYSCTL_OUT(req, &xs32, sizeof(xs32)); 2584 return (error); 2585 } 2586 #endif 2587 #if defined(COMPAT_FREEBSD11) 2588 if (req->oldlen == sizeof(xs11)) { 2589 xs11.xsw_version = XSWDEV_VERSION_11; 2590 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2591 xs11.xsw_flags = xs.xsw_flags; 2592 xs11.xsw_nblks = xs.xsw_nblks; 2593 xs11.xsw_used = xs.xsw_used; 2594 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2595 return (error); 2596 } 2597 #endif 2598 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2599 return (error); 2600 } 2601 2602 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2603 "Number of swap devices"); 2604 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2605 sysctl_vm_swap_info, 2606 "Swap statistics by device"); 2607 2608 /* 2609 * Count the approximate swap usage in pages for a vmspace. The 2610 * shadowed or not yet copied on write swap blocks are not accounted. 2611 * The map must be locked. 2612 */ 2613 long 2614 vmspace_swap_count(struct vmspace *vmspace) 2615 { 2616 vm_map_t map; 2617 vm_map_entry_t cur; 2618 vm_object_t object; 2619 struct swblk *sb; 2620 vm_pindex_t e, pi; 2621 long count; 2622 int i; 2623 2624 map = &vmspace->vm_map; 2625 count = 0; 2626 2627 for (cur = map->header.next; cur != &map->header; cur = cur->next) { 2628 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 2629 continue; 2630 object = cur->object.vm_object; 2631 if (object == NULL || object->type != OBJT_SWAP) 2632 continue; 2633 VM_OBJECT_RLOCK(object); 2634 if (object->type != OBJT_SWAP) 2635 goto unlock; 2636 pi = OFF_TO_IDX(cur->offset); 2637 e = pi + OFF_TO_IDX(cur->end - cur->start); 2638 for (;; pi = sb->p + SWAP_META_PAGES) { 2639 sb = SWAP_PCTRIE_LOOKUP_GE( 2640 &object->un_pager.swp.swp_blks, pi); 2641 if (sb == NULL || sb->p >= e) 2642 break; 2643 for (i = 0; i < SWAP_META_PAGES; i++) { 2644 if (sb->p + i < e && 2645 sb->d[i] != SWAPBLK_NONE) 2646 count++; 2647 } 2648 } 2649 unlock: 2650 VM_OBJECT_RUNLOCK(object); 2651 } 2652 return (count); 2653 } 2654 2655 /* 2656 * GEOM backend 2657 * 2658 * Swapping onto disk devices. 2659 * 2660 */ 2661 2662 static g_orphan_t swapgeom_orphan; 2663 2664 static struct g_class g_swap_class = { 2665 .name = "SWAP", 2666 .version = G_VERSION, 2667 .orphan = swapgeom_orphan, 2668 }; 2669 2670 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2671 2672 2673 static void 2674 swapgeom_close_ev(void *arg, int flags) 2675 { 2676 struct g_consumer *cp; 2677 2678 cp = arg; 2679 g_access(cp, -1, -1, 0); 2680 g_detach(cp); 2681 g_destroy_consumer(cp); 2682 } 2683 2684 /* 2685 * Add a reference to the g_consumer for an inflight transaction. 2686 */ 2687 static void 2688 swapgeom_acquire(struct g_consumer *cp) 2689 { 2690 2691 mtx_assert(&sw_dev_mtx, MA_OWNED); 2692 cp->index++; 2693 } 2694 2695 /* 2696 * Remove a reference from the g_consumer. Post a close event if all 2697 * references go away, since the function might be called from the 2698 * biodone context. 2699 */ 2700 static void 2701 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2702 { 2703 2704 mtx_assert(&sw_dev_mtx, MA_OWNED); 2705 cp->index--; 2706 if (cp->index == 0) { 2707 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2708 sp->sw_id = NULL; 2709 } 2710 } 2711 2712 static void 2713 swapgeom_done(struct bio *bp2) 2714 { 2715 struct swdevt *sp; 2716 struct buf *bp; 2717 struct g_consumer *cp; 2718 2719 bp = bp2->bio_caller2; 2720 cp = bp2->bio_from; 2721 bp->b_ioflags = bp2->bio_flags; 2722 if (bp2->bio_error) 2723 bp->b_ioflags |= BIO_ERROR; 2724 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2725 bp->b_error = bp2->bio_error; 2726 bp->b_caller1 = NULL; 2727 bufdone(bp); 2728 sp = bp2->bio_caller1; 2729 mtx_lock(&sw_dev_mtx); 2730 swapgeom_release(cp, sp); 2731 mtx_unlock(&sw_dev_mtx); 2732 g_destroy_bio(bp2); 2733 } 2734 2735 static void 2736 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2737 { 2738 struct bio *bio; 2739 struct g_consumer *cp; 2740 2741 mtx_lock(&sw_dev_mtx); 2742 cp = sp->sw_id; 2743 if (cp == NULL) { 2744 mtx_unlock(&sw_dev_mtx); 2745 bp->b_error = ENXIO; 2746 bp->b_ioflags |= BIO_ERROR; 2747 bufdone(bp); 2748 return; 2749 } 2750 swapgeom_acquire(cp); 2751 mtx_unlock(&sw_dev_mtx); 2752 if (bp->b_iocmd == BIO_WRITE) 2753 bio = g_new_bio(); 2754 else 2755 bio = g_alloc_bio(); 2756 if (bio == NULL) { 2757 mtx_lock(&sw_dev_mtx); 2758 swapgeom_release(cp, sp); 2759 mtx_unlock(&sw_dev_mtx); 2760 bp->b_error = ENOMEM; 2761 bp->b_ioflags |= BIO_ERROR; 2762 printf("swap_pager: cannot allocate bio\n"); 2763 bufdone(bp); 2764 return; 2765 } 2766 2767 bp->b_caller1 = bio; 2768 bio->bio_caller1 = sp; 2769 bio->bio_caller2 = bp; 2770 bio->bio_cmd = bp->b_iocmd; 2771 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2772 bio->bio_length = bp->b_bcount; 2773 bio->bio_done = swapgeom_done; 2774 if (!buf_mapped(bp)) { 2775 bio->bio_ma = bp->b_pages; 2776 bio->bio_data = unmapped_buf; 2777 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2778 bio->bio_ma_n = bp->b_npages; 2779 bio->bio_flags |= BIO_UNMAPPED; 2780 } else { 2781 bio->bio_data = bp->b_data; 2782 bio->bio_ma = NULL; 2783 } 2784 g_io_request(bio, cp); 2785 return; 2786 } 2787 2788 static void 2789 swapgeom_orphan(struct g_consumer *cp) 2790 { 2791 struct swdevt *sp; 2792 int destroy; 2793 2794 mtx_lock(&sw_dev_mtx); 2795 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2796 if (sp->sw_id == cp) { 2797 sp->sw_flags |= SW_CLOSING; 2798 break; 2799 } 2800 } 2801 /* 2802 * Drop reference we were created with. Do directly since we're in a 2803 * special context where we don't have to queue the call to 2804 * swapgeom_close_ev(). 2805 */ 2806 cp->index--; 2807 destroy = ((sp != NULL) && (cp->index == 0)); 2808 if (destroy) 2809 sp->sw_id = NULL; 2810 mtx_unlock(&sw_dev_mtx); 2811 if (destroy) 2812 swapgeom_close_ev(cp, 0); 2813 } 2814 2815 static void 2816 swapgeom_close(struct thread *td, struct swdevt *sw) 2817 { 2818 struct g_consumer *cp; 2819 2820 mtx_lock(&sw_dev_mtx); 2821 cp = sw->sw_id; 2822 sw->sw_id = NULL; 2823 mtx_unlock(&sw_dev_mtx); 2824 2825 /* 2826 * swapgeom_close() may be called from the biodone context, 2827 * where we cannot perform topology changes. Delegate the 2828 * work to the events thread. 2829 */ 2830 if (cp != NULL) 2831 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2832 } 2833 2834 static int 2835 swapongeom_locked(struct cdev *dev, struct vnode *vp) 2836 { 2837 struct g_provider *pp; 2838 struct g_consumer *cp; 2839 static struct g_geom *gp; 2840 struct swdevt *sp; 2841 u_long nblks; 2842 int error; 2843 2844 pp = g_dev_getprovider(dev); 2845 if (pp == NULL) 2846 return (ENODEV); 2847 mtx_lock(&sw_dev_mtx); 2848 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2849 cp = sp->sw_id; 2850 if (cp != NULL && cp->provider == pp) { 2851 mtx_unlock(&sw_dev_mtx); 2852 return (EBUSY); 2853 } 2854 } 2855 mtx_unlock(&sw_dev_mtx); 2856 if (gp == NULL) 2857 gp = g_new_geomf(&g_swap_class, "swap"); 2858 cp = g_new_consumer(gp); 2859 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2860 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2861 g_attach(cp, pp); 2862 /* 2863 * XXX: Every time you think you can improve the margin for 2864 * footshooting, somebody depends on the ability to do so: 2865 * savecore(8) wants to write to our swapdev so we cannot 2866 * set an exclusive count :-( 2867 */ 2868 error = g_access(cp, 1, 1, 0); 2869 if (error != 0) { 2870 g_detach(cp); 2871 g_destroy_consumer(cp); 2872 return (error); 2873 } 2874 nblks = pp->mediasize / DEV_BSIZE; 2875 swaponsomething(vp, cp, nblks, swapgeom_strategy, 2876 swapgeom_close, dev2udev(dev), 2877 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2878 return (0); 2879 } 2880 2881 static int 2882 swapongeom(struct vnode *vp) 2883 { 2884 int error; 2885 2886 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2887 if (vp->v_type != VCHR || (vp->v_iflag & VI_DOOMED) != 0) { 2888 error = ENOENT; 2889 } else { 2890 g_topology_lock(); 2891 error = swapongeom_locked(vp->v_rdev, vp); 2892 g_topology_unlock(); 2893 } 2894 VOP_UNLOCK(vp, 0); 2895 return (error); 2896 } 2897 2898 /* 2899 * VNODE backend 2900 * 2901 * This is used mainly for network filesystem (read: probably only tested 2902 * with NFS) swapfiles. 2903 * 2904 */ 2905 2906 static void 2907 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2908 { 2909 struct vnode *vp2; 2910 2911 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2912 2913 vp2 = sp->sw_id; 2914 vhold(vp2); 2915 if (bp->b_iocmd == BIO_WRITE) { 2916 if (bp->b_bufobj) 2917 bufobj_wdrop(bp->b_bufobj); 2918 bufobj_wref(&vp2->v_bufobj); 2919 } 2920 if (bp->b_bufobj != &vp2->v_bufobj) 2921 bp->b_bufobj = &vp2->v_bufobj; 2922 bp->b_vp = vp2; 2923 bp->b_iooffset = dbtob(bp->b_blkno); 2924 bstrategy(bp); 2925 return; 2926 } 2927 2928 static void 2929 swapdev_close(struct thread *td, struct swdevt *sp) 2930 { 2931 2932 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2933 vrele(sp->sw_vp); 2934 } 2935 2936 2937 static int 2938 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2939 { 2940 struct swdevt *sp; 2941 int error; 2942 2943 if (nblks == 0) 2944 return (ENXIO); 2945 mtx_lock(&sw_dev_mtx); 2946 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2947 if (sp->sw_id == vp) { 2948 mtx_unlock(&sw_dev_mtx); 2949 return (EBUSY); 2950 } 2951 } 2952 mtx_unlock(&sw_dev_mtx); 2953 2954 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2955 #ifdef MAC 2956 error = mac_system_check_swapon(td->td_ucred, vp); 2957 if (error == 0) 2958 #endif 2959 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 2960 (void) VOP_UNLOCK(vp, 0); 2961 if (error) 2962 return (error); 2963 2964 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 2965 NODEV, 0); 2966 return (0); 2967 } 2968 2969 static int 2970 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 2971 { 2972 int error, new, n; 2973 2974 new = nsw_wcount_async_max; 2975 error = sysctl_handle_int(oidp, &new, 0, req); 2976 if (error != 0 || req->newptr == NULL) 2977 return (error); 2978 2979 if (new > nswbuf / 2 || new < 1) 2980 return (EINVAL); 2981 2982 mtx_lock(&swbuf_mtx); 2983 while (nsw_wcount_async_max != new) { 2984 /* 2985 * Adjust difference. If the current async count is too low, 2986 * we will need to sqeeze our update slowly in. Sleep with a 2987 * higher priority than getpbuf() to finish faster. 2988 */ 2989 n = new - nsw_wcount_async_max; 2990 if (nsw_wcount_async + n >= 0) { 2991 nsw_wcount_async += n; 2992 nsw_wcount_async_max += n; 2993 wakeup(&nsw_wcount_async); 2994 } else { 2995 nsw_wcount_async_max -= nsw_wcount_async; 2996 nsw_wcount_async = 0; 2997 msleep(&nsw_wcount_async, &swbuf_mtx, PSWP, 2998 "swpsysctl", 0); 2999 } 3000 } 3001 mtx_unlock(&swbuf_mtx); 3002 3003 return (0); 3004 } 3005