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