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 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 325 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 326 static struct mtx swbuf_mtx; /* to sync nsw_wcount_async */ 327 static int nsw_wcount_async; /* limit async write buffers */ 328 static int nsw_wcount_async_max;/* assigned maximum */ 329 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 330 331 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 332 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 333 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 334 "Maximum running async swap ops"); 335 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS); 336 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD | 337 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A", 338 "Swap Fragmentation Info"); 339 340 static struct sx sw_alloc_sx; 341 342 /* 343 * "named" and "unnamed" anon region objects. Try to reduce the overhead 344 * of searching a named list by hashing it just a little. 345 */ 346 347 #define NOBJLISTS 8 348 349 #define NOBJLIST(handle) \ 350 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 351 352 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 353 static uma_zone_t swwbuf_zone; 354 static uma_zone_t swrbuf_zone; 355 static uma_zone_t swblk_zone; 356 static uma_zone_t swpctrie_zone; 357 358 /* 359 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 360 * calls hooked from other parts of the VM system and do not appear here. 361 * (see vm/swap_pager.h). 362 */ 363 static vm_object_t 364 swap_pager_alloc(void *handle, vm_ooffset_t size, 365 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 366 static void swap_pager_dealloc(vm_object_t object); 367 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, 368 int *); 369 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, 370 int *, pgo_getpages_iodone_t, void *); 371 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 372 static boolean_t 373 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 374 static void swap_pager_init(void); 375 static void swap_pager_unswapped(vm_page_t); 376 static void swap_pager_swapoff(struct swdevt *sp); 377 static void swap_pager_update_writecount(vm_object_t object, 378 vm_offset_t start, vm_offset_t end); 379 static void swap_pager_release_writecount(vm_object_t object, 380 vm_offset_t start, vm_offset_t end); 381 382 struct pagerops swappagerops = { 383 .pgo_init = swap_pager_init, /* early system initialization of pager */ 384 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 385 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 386 .pgo_getpages = swap_pager_getpages, /* pagein */ 387 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 388 .pgo_putpages = swap_pager_putpages, /* pageout */ 389 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 390 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 391 .pgo_update_writecount = swap_pager_update_writecount, 392 .pgo_release_writecount = swap_pager_release_writecount, 393 }; 394 395 /* 396 * swap_*() routines are externally accessible. swp_*() routines are 397 * internal. 398 */ 399 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 400 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 401 402 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 403 "Maximum size of a swap block in pages"); 404 405 static void swp_sizecheck(void); 406 static void swp_pager_async_iodone(struct buf *bp); 407 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit); 408 static void swp_pager_free_empty_swblk(vm_object_t, struct swblk *sb); 409 static int swapongeom(struct vnode *); 410 static int swaponvp(struct thread *, struct vnode *, u_long); 411 static int swapoff_one(struct swdevt *sp, struct ucred *cred); 412 413 /* 414 * Swap bitmap functions 415 */ 416 static void swp_pager_freeswapspace(daddr_t blk, daddr_t npages); 417 static daddr_t swp_pager_getswapspace(int *npages, int limit); 418 419 /* 420 * Metadata functions 421 */ 422 static daddr_t swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 423 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 424 static void swp_pager_meta_transfer(vm_object_t src, vm_object_t dst, 425 vm_pindex_t pindex, vm_pindex_t count); 426 static void swp_pager_meta_free_all(vm_object_t); 427 static daddr_t swp_pager_meta_lookup(vm_object_t, vm_pindex_t); 428 429 static void 430 swp_pager_init_freerange(daddr_t *start, daddr_t *num) 431 { 432 433 *start = SWAPBLK_NONE; 434 *num = 0; 435 } 436 437 static void 438 swp_pager_update_freerange(daddr_t *start, daddr_t *num, daddr_t addr) 439 { 440 441 if (*start + *num == addr) { 442 (*num)++; 443 } else { 444 swp_pager_freeswapspace(*start, *num); 445 *start = addr; 446 *num = 1; 447 } 448 } 449 450 static void * 451 swblk_trie_alloc(struct pctrie *ptree) 452 { 453 454 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? 455 M_USE_RESERVE : 0))); 456 } 457 458 static void 459 swblk_trie_free(struct pctrie *ptree, void *node) 460 { 461 462 uma_zfree(swpctrie_zone, node); 463 } 464 465 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); 466 467 /* 468 * SWP_SIZECHECK() - update swap_pager_full indication 469 * 470 * update the swap_pager_almost_full indication and warn when we are 471 * about to run out of swap space, using lowat/hiwat hysteresis. 472 * 473 * Clear swap_pager_full ( task killing ) indication when lowat is met. 474 * 475 * No restrictions on call 476 * This routine may not block. 477 */ 478 static void 479 swp_sizecheck(void) 480 { 481 482 if (swap_pager_avail < nswap_lowat) { 483 if (swap_pager_almost_full == 0) { 484 printf("swap_pager: out of swap space\n"); 485 swap_pager_almost_full = 1; 486 } 487 } else { 488 swap_pager_full = 0; 489 if (swap_pager_avail > nswap_hiwat) 490 swap_pager_almost_full = 0; 491 } 492 } 493 494 /* 495 * SWAP_PAGER_INIT() - initialize the swap pager! 496 * 497 * Expected to be started from system init. NOTE: This code is run 498 * before much else so be careful what you depend on. Most of the VM 499 * system has yet to be initialized at this point. 500 */ 501 static void 502 swap_pager_init(void) 503 { 504 /* 505 * Initialize object lists 506 */ 507 int i; 508 509 for (i = 0; i < NOBJLISTS; ++i) 510 TAILQ_INIT(&swap_pager_object_list[i]); 511 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 512 sx_init(&sw_alloc_sx, "swspsx"); 513 sx_init(&swdev_syscall_lock, "swsysc"); 514 } 515 516 /* 517 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 518 * 519 * Expected to be started from pageout process once, prior to entering 520 * its main loop. 521 */ 522 void 523 swap_pager_swap_init(void) 524 { 525 unsigned long n, n2; 526 527 /* 528 * Number of in-transit swap bp operations. Don't 529 * exhaust the pbufs completely. Make sure we 530 * initialize workable values (0 will work for hysteresis 531 * but it isn't very efficient). 532 * 533 * The nsw_cluster_max is constrained by the bp->b_pages[] 534 * array, which has MAXPHYS / PAGE_SIZE entries, and our locally 535 * defined MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 536 * constrained by the swap device interleave stripe size. 537 * 538 * Currently we hardwire nsw_wcount_async to 4. This limit is 539 * designed to prevent other I/O from having high latencies due to 540 * our pageout I/O. The value 4 works well for one or two active swap 541 * devices but is probably a little low if you have more. Even so, 542 * a higher value would probably generate only a limited improvement 543 * with three or four active swap devices since the system does not 544 * typically have to pageout at extreme bandwidths. We will want 545 * at least 2 per swap devices, and 4 is a pretty good value if you 546 * have one NFS swap device due to the command/ack latency over NFS. 547 * So it all works out pretty well. 548 */ 549 nsw_cluster_max = min(MAXPHYS / PAGE_SIZE, MAX_PAGEOUT_CLUSTER); 550 551 nsw_wcount_async = 4; 552 nsw_wcount_async_max = nsw_wcount_async; 553 mtx_init(&swbuf_mtx, "async swbuf mutex", NULL, MTX_DEF); 554 555 swwbuf_zone = pbuf_zsecond_create("swwbuf", nswbuf / 4); 556 swrbuf_zone = pbuf_zsecond_create("swrbuf", nswbuf / 2); 557 558 /* 559 * Initialize our zone, taking the user's requested size or 560 * estimating the number we need based on the number of pages 561 * in the system. 562 */ 563 n = maxswzone != 0 ? maxswzone / sizeof(struct swblk) : 564 vm_cnt.v_page_count / 2; 565 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, 566 pctrie_zone_init, NULL, UMA_ALIGN_PTR, UMA_ZONE_VM); 567 if (swpctrie_zone == NULL) 568 panic("failed to create swap pctrie zone."); 569 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, 570 NULL, NULL, _Alignof(struct swblk) - 1, UMA_ZONE_VM); 571 if (swblk_zone == NULL) 572 panic("failed to create swap blk zone."); 573 n2 = n; 574 do { 575 if (uma_zone_reserve_kva(swblk_zone, n)) 576 break; 577 /* 578 * if the allocation failed, try a zone two thirds the 579 * size of the previous attempt. 580 */ 581 n -= ((n + 2) / 3); 582 } while (n > 0); 583 584 /* 585 * Often uma_zone_reserve_kva() cannot reserve exactly the 586 * requested size. Account for the difference when 587 * calculating swap_maxpages. 588 */ 589 n = uma_zone_get_max(swblk_zone); 590 591 if (n < n2) 592 printf("Swap blk zone entries changed from %lu to %lu.\n", 593 n2, n); 594 /* absolute maximum we can handle assuming 100% efficiency */ 595 swap_maxpages = n * SWAP_META_PAGES; 596 swzone = n * sizeof(struct swblk); 597 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 598 printf("Cannot reserve swap pctrie zone, " 599 "reduce kern.maxswzone.\n"); 600 } 601 602 static vm_object_t 603 swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size, 604 vm_ooffset_t offset) 605 { 606 vm_object_t object; 607 608 if (cred != NULL) { 609 if (!swap_reserve_by_cred(size, cred)) 610 return (NULL); 611 crhold(cred); 612 } 613 614 /* 615 * The un_pager.swp.swp_blks trie is initialized by 616 * vm_object_allocate() to ensure the correct order of 617 * visibility to other threads. 618 */ 619 object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset + 620 PAGE_MASK + size)); 621 622 object->un_pager.swp.writemappings = 0; 623 object->handle = handle; 624 if (cred != NULL) { 625 object->cred = cred; 626 object->charge = size; 627 } 628 return (object); 629 } 630 631 /* 632 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 633 * its metadata structures. 634 * 635 * This routine is called from the mmap and fork code to create a new 636 * OBJT_SWAP object. 637 * 638 * This routine must ensure that no live duplicate is created for 639 * the named object request, which is protected against by 640 * holding the sw_alloc_sx lock in case handle != NULL. 641 */ 642 static vm_object_t 643 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 644 vm_ooffset_t offset, struct ucred *cred) 645 { 646 vm_object_t object; 647 648 if (handle != NULL) { 649 /* 650 * Reference existing named region or allocate new one. There 651 * should not be a race here against swp_pager_meta_build() 652 * as called from vm_page_remove() in regards to the lookup 653 * of the handle. 654 */ 655 sx_xlock(&sw_alloc_sx); 656 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 657 if (object == NULL) { 658 object = swap_pager_alloc_init(handle, cred, size, 659 offset); 660 if (object != NULL) { 661 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 662 object, pager_object_list); 663 } 664 } 665 sx_xunlock(&sw_alloc_sx); 666 } else { 667 object = swap_pager_alloc_init(handle, cred, size, offset); 668 } 669 return (object); 670 } 671 672 /* 673 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 674 * 675 * The swap backing for the object is destroyed. The code is 676 * designed such that we can reinstantiate it later, but this 677 * routine is typically called only when the entire object is 678 * about to be destroyed. 679 * 680 * The object must be locked. 681 */ 682 static void 683 swap_pager_dealloc(vm_object_t object) 684 { 685 686 VM_OBJECT_ASSERT_WLOCKED(object); 687 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 688 689 /* 690 * Remove from list right away so lookups will fail if we block for 691 * pageout completion. 692 */ 693 if (object->handle != NULL) { 694 VM_OBJECT_WUNLOCK(object); 695 sx_xlock(&sw_alloc_sx); 696 TAILQ_REMOVE(NOBJLIST(object->handle), object, 697 pager_object_list); 698 sx_xunlock(&sw_alloc_sx); 699 VM_OBJECT_WLOCK(object); 700 } 701 702 vm_object_pip_wait(object, "swpdea"); 703 704 /* 705 * Free all remaining metadata. We only bother to free it from 706 * the swap meta data. We do not attempt to free swapblk's still 707 * associated with vm_page_t's for this object. We do not care 708 * if paging is still in progress on some objects. 709 */ 710 swp_pager_meta_free_all(object); 711 object->handle = NULL; 712 object->type = OBJT_DEAD; 713 } 714 715 /************************************************************************ 716 * SWAP PAGER BITMAP ROUTINES * 717 ************************************************************************/ 718 719 /* 720 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 721 * 722 * Allocate swap for up to the requested number of pages, and at 723 * least a minimum number of pages. The starting swap block number 724 * (a page index) is returned or SWAPBLK_NONE if the allocation 725 * failed. 726 * 727 * Also has the side effect of advising that somebody made a mistake 728 * when they configured swap and didn't configure enough. 729 * 730 * This routine may not sleep. 731 * 732 * We allocate in round-robin fashion from the configured devices. 733 */ 734 static daddr_t 735 swp_pager_getswapspace(int *io_npages, int limit) 736 { 737 daddr_t blk; 738 struct swdevt *sp; 739 int mpages, npages; 740 741 blk = SWAPBLK_NONE; 742 mpages = *io_npages; 743 npages = imin(BLIST_MAX_ALLOC, mpages); 744 mtx_lock(&sw_dev_mtx); 745 sp = swdevhd; 746 while (!TAILQ_EMPTY(&swtailq)) { 747 if (sp == NULL) 748 sp = TAILQ_FIRST(&swtailq); 749 if ((sp->sw_flags & SW_CLOSING) == 0) 750 blk = blist_alloc(sp->sw_blist, &npages, mpages); 751 if (blk != SWAPBLK_NONE) 752 break; 753 sp = TAILQ_NEXT(sp, sw_list); 754 if (swdevhd == sp) { 755 if (npages <= limit) 756 break; 757 mpages = npages - 1; 758 npages >>= 1; 759 } 760 } 761 if (blk != SWAPBLK_NONE) { 762 *io_npages = npages; 763 blk += sp->sw_first; 764 sp->sw_used += npages; 765 swap_pager_avail -= npages; 766 swp_sizecheck(); 767 swdevhd = TAILQ_NEXT(sp, sw_list); 768 } else { 769 if (swap_pager_full != 2) { 770 printf("swp_pager_getswapspace(%d): failed\n", 771 *io_npages); 772 swap_pager_full = 2; 773 swap_pager_almost_full = 1; 774 } 775 swdevhd = NULL; 776 } 777 mtx_unlock(&sw_dev_mtx); 778 return (blk); 779 } 780 781 static bool 782 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 783 { 784 785 return (blk >= sp->sw_first && blk < sp->sw_end); 786 } 787 788 static void 789 swp_pager_strategy(struct buf *bp) 790 { 791 struct swdevt *sp; 792 793 mtx_lock(&sw_dev_mtx); 794 TAILQ_FOREACH(sp, &swtailq, sw_list) { 795 if (swp_pager_isondev(bp->b_blkno, sp)) { 796 mtx_unlock(&sw_dev_mtx); 797 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 798 unmapped_buf_allowed) { 799 bp->b_data = unmapped_buf; 800 bp->b_offset = 0; 801 } else { 802 pmap_qenter((vm_offset_t)bp->b_data, 803 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 804 } 805 sp->sw_strategy(bp, sp); 806 return; 807 } 808 } 809 panic("Swapdev not found"); 810 } 811 812 813 /* 814 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 815 * 816 * This routine returns the specified swap blocks back to the bitmap. 817 * 818 * This routine may not sleep. 819 */ 820 static void 821 swp_pager_freeswapspace(daddr_t blk, daddr_t npages) 822 { 823 struct swdevt *sp; 824 825 if (npages == 0) 826 return; 827 mtx_lock(&sw_dev_mtx); 828 TAILQ_FOREACH(sp, &swtailq, sw_list) { 829 if (swp_pager_isondev(blk, sp)) { 830 sp->sw_used -= npages; 831 /* 832 * If we are attempting to stop swapping on 833 * this device, we don't want to mark any 834 * blocks free lest they be reused. 835 */ 836 if ((sp->sw_flags & SW_CLOSING) == 0) { 837 blist_free(sp->sw_blist, blk - sp->sw_first, 838 npages); 839 swap_pager_avail += npages; 840 swp_sizecheck(); 841 } 842 mtx_unlock(&sw_dev_mtx); 843 return; 844 } 845 } 846 panic("Swapdev not found"); 847 } 848 849 /* 850 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 851 */ 852 static int 853 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 854 { 855 struct sbuf sbuf; 856 struct swdevt *sp; 857 const char *devname; 858 int error; 859 860 error = sysctl_wire_old_buffer(req, 0); 861 if (error != 0) 862 return (error); 863 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 864 mtx_lock(&sw_dev_mtx); 865 TAILQ_FOREACH(sp, &swtailq, sw_list) { 866 if (vn_isdisk(sp->sw_vp, NULL)) 867 devname = devtoname(sp->sw_vp->v_rdev); 868 else 869 devname = "[file]"; 870 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 871 blist_stats(sp->sw_blist, &sbuf); 872 } 873 mtx_unlock(&sw_dev_mtx); 874 error = sbuf_finish(&sbuf); 875 sbuf_delete(&sbuf); 876 return (error); 877 } 878 879 /* 880 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 881 * range within an object. 882 * 883 * This is a globally accessible routine. 884 * 885 * This routine removes swapblk assignments from swap metadata. 886 * 887 * The external callers of this routine typically have already destroyed 888 * or renamed vm_page_t's associated with this range in the object so 889 * we should be ok. 890 * 891 * The object must be locked. 892 */ 893 void 894 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 895 { 896 897 swp_pager_meta_free(object, start, size); 898 } 899 900 /* 901 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 902 * 903 * Assigns swap blocks to the specified range within the object. The 904 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 905 * 906 * Returns 0 on success, -1 on failure. 907 */ 908 int 909 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 910 { 911 daddr_t addr, blk, n_free, s_free; 912 int i, j, n; 913 914 swp_pager_init_freerange(&s_free, &n_free); 915 VM_OBJECT_WLOCK(object); 916 for (i = 0; i < size; i += n) { 917 n = size - i; 918 blk = swp_pager_getswapspace(&n, 1); 919 if (blk == SWAPBLK_NONE) { 920 swp_pager_meta_free(object, start, i); 921 VM_OBJECT_WUNLOCK(object); 922 return (-1); 923 } 924 for (j = 0; j < n; ++j) { 925 addr = swp_pager_meta_build(object, 926 start + i + j, blk + j); 927 if (addr != SWAPBLK_NONE) 928 swp_pager_update_freerange(&s_free, &n_free, 929 addr); 930 } 931 } 932 swp_pager_freeswapspace(s_free, n_free); 933 VM_OBJECT_WUNLOCK(object); 934 return (0); 935 } 936 937 static bool 938 swp_pager_xfer_source(vm_object_t srcobject, vm_object_t dstobject, 939 vm_pindex_t pindex, daddr_t addr) 940 { 941 daddr_t dstaddr; 942 943 KASSERT(srcobject->type == OBJT_SWAP, 944 ("%s: Srcobject not swappable", __func__)); 945 if (dstobject->type == OBJT_SWAP && 946 swp_pager_meta_lookup(dstobject, pindex) != SWAPBLK_NONE) { 947 /* Caller should destroy the source block. */ 948 return (false); 949 } 950 951 /* 952 * Destination has no swapblk and is not resident, transfer source. 953 * swp_pager_meta_build() can sleep. 954 */ 955 vm_object_pip_add(srcobject, 1); 956 VM_OBJECT_WUNLOCK(srcobject); 957 vm_object_pip_add(dstobject, 1); 958 dstaddr = swp_pager_meta_build(dstobject, pindex, addr); 959 KASSERT(dstaddr == SWAPBLK_NONE, 960 ("Unexpected destination swapblk")); 961 vm_object_pip_wakeup(dstobject); 962 VM_OBJECT_WLOCK(srcobject); 963 vm_object_pip_wakeup(srcobject); 964 return (true); 965 } 966 967 /* 968 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 969 * and destroy the source. 970 * 971 * Copy any valid swapblks from the source to the destination. In 972 * cases where both the source and destination have a valid swapblk, 973 * we keep the destination's. 974 * 975 * This routine is allowed to sleep. It may sleep allocating metadata 976 * indirectly through swp_pager_meta_build() or if paging is still in 977 * progress on the source. 978 * 979 * The source object contains no vm_page_t's (which is just as well) 980 * 981 * The source object is of type OBJT_SWAP. 982 * 983 * The source and destination objects must be locked. 984 * Both object locks may temporarily be released. 985 */ 986 void 987 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 988 vm_pindex_t offset, int destroysource) 989 { 990 991 VM_OBJECT_ASSERT_WLOCKED(srcobject); 992 VM_OBJECT_ASSERT_WLOCKED(dstobject); 993 994 /* 995 * If destroysource is set, we remove the source object from the 996 * swap_pager internal queue now. 997 */ 998 if (destroysource && srcobject->handle != NULL) { 999 vm_object_pip_add(srcobject, 1); 1000 VM_OBJECT_WUNLOCK(srcobject); 1001 vm_object_pip_add(dstobject, 1); 1002 VM_OBJECT_WUNLOCK(dstobject); 1003 sx_xlock(&sw_alloc_sx); 1004 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 1005 pager_object_list); 1006 sx_xunlock(&sw_alloc_sx); 1007 VM_OBJECT_WLOCK(dstobject); 1008 vm_object_pip_wakeup(dstobject); 1009 VM_OBJECT_WLOCK(srcobject); 1010 vm_object_pip_wakeup(srcobject); 1011 } 1012 1013 /* 1014 * Transfer source to destination. 1015 */ 1016 swp_pager_meta_transfer(srcobject, dstobject, offset, dstobject->size); 1017 1018 /* 1019 * Free left over swap blocks in source. 1020 * 1021 * We have to revert the type to OBJT_DEFAULT so we do not accidentally 1022 * double-remove the object from the swap queues. 1023 */ 1024 if (destroysource) { 1025 swp_pager_meta_free_all(srcobject); 1026 /* 1027 * Reverting the type is not necessary, the caller is going 1028 * to destroy srcobject directly, but I'm doing it here 1029 * for consistency since we've removed the object from its 1030 * queues. 1031 */ 1032 srcobject->type = OBJT_DEFAULT; 1033 } 1034 } 1035 1036 /* 1037 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1038 * the requested page. 1039 * 1040 * We determine whether good backing store exists for the requested 1041 * page and return TRUE if it does, FALSE if it doesn't. 1042 * 1043 * If TRUE, we also try to determine how much valid, contiguous backing 1044 * store exists before and after the requested page. 1045 */ 1046 static boolean_t 1047 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1048 int *after) 1049 { 1050 daddr_t blk, blk0; 1051 int i; 1052 1053 VM_OBJECT_ASSERT_LOCKED(object); 1054 KASSERT(object->type == OBJT_SWAP, 1055 ("%s: object not swappable", __func__)); 1056 1057 /* 1058 * do we have good backing store at the requested index ? 1059 */ 1060 blk0 = swp_pager_meta_lookup(object, pindex); 1061 if (blk0 == SWAPBLK_NONE) { 1062 if (before) 1063 *before = 0; 1064 if (after) 1065 *after = 0; 1066 return (FALSE); 1067 } 1068 1069 /* 1070 * find backwards-looking contiguous good backing store 1071 */ 1072 if (before != NULL) { 1073 for (i = 1; i < SWB_NPAGES; i++) { 1074 if (i > pindex) 1075 break; 1076 blk = swp_pager_meta_lookup(object, pindex - i); 1077 if (blk != blk0 - i) 1078 break; 1079 } 1080 *before = i - 1; 1081 } 1082 1083 /* 1084 * find forward-looking contiguous good backing store 1085 */ 1086 if (after != NULL) { 1087 for (i = 1; i < SWB_NPAGES; i++) { 1088 blk = swp_pager_meta_lookup(object, pindex + i); 1089 if (blk != blk0 + i) 1090 break; 1091 } 1092 *after = i - 1; 1093 } 1094 return (TRUE); 1095 } 1096 1097 /* 1098 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1099 * 1100 * This removes any associated swap backing store, whether valid or 1101 * not, from the page. 1102 * 1103 * This routine is typically called when a page is made dirty, at 1104 * which point any associated swap can be freed. MADV_FREE also 1105 * calls us in a special-case situation 1106 * 1107 * NOTE!!! If the page is clean and the swap was valid, the caller 1108 * should make the page dirty before calling this routine. This routine 1109 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1110 * depends on it. 1111 * 1112 * This routine may not sleep. 1113 * 1114 * The object containing the page must be locked. 1115 */ 1116 static void 1117 swap_pager_unswapped(vm_page_t m) 1118 { 1119 struct swblk *sb; 1120 1121 VM_OBJECT_ASSERT_WLOCKED(m->object); 1122 1123 /* 1124 * The meta data only exists if the object is OBJT_SWAP 1125 * and even then might not be allocated yet. 1126 */ 1127 KASSERT(m->object->type == OBJT_SWAP, 1128 ("Free object not swappable")); 1129 1130 sb = SWAP_PCTRIE_LOOKUP(&m->object->un_pager.swp.swp_blks, 1131 rounddown(m->pindex, SWAP_META_PAGES)); 1132 if (sb == NULL) 1133 return; 1134 if (sb->d[m->pindex % SWAP_META_PAGES] == SWAPBLK_NONE) 1135 return; 1136 swp_pager_freeswapspace(sb->d[m->pindex % SWAP_META_PAGES], 1); 1137 sb->d[m->pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 1138 swp_pager_free_empty_swblk(m->object, sb); 1139 } 1140 1141 /* 1142 * swap_pager_getpages() - bring pages in from swap 1143 * 1144 * Attempt to page in the pages in array "ma" of length "count". The 1145 * caller may optionally specify that additional pages preceding and 1146 * succeeding the specified range be paged in. The number of such pages 1147 * is returned in the "rbehind" and "rahead" parameters, and they will 1148 * be in the inactive queue upon return. 1149 * 1150 * The pages in "ma" must be busied and will remain busied upon return. 1151 */ 1152 static int 1153 swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count, int *rbehind, 1154 int *rahead) 1155 { 1156 struct buf *bp; 1157 vm_page_t bm, mpred, msucc, p; 1158 vm_pindex_t pindex; 1159 daddr_t blk; 1160 int i, maxahead, maxbehind, reqcount; 1161 1162 reqcount = count; 1163 1164 /* 1165 * Determine the final number of read-behind pages and 1166 * allocate them BEFORE releasing the object lock. Otherwise, 1167 * there can be a problematic race with vm_object_split(). 1168 * Specifically, vm_object_split() might first transfer pages 1169 * that precede ma[0] in the current object to a new object, 1170 * and then this function incorrectly recreates those pages as 1171 * read-behind pages in the current object. 1172 */ 1173 KASSERT(object->type == OBJT_SWAP, 1174 ("%s: object not swappable", __func__)); 1175 if (!swap_pager_haspage(object, ma[0]->pindex, &maxbehind, &maxahead)) 1176 return (VM_PAGER_FAIL); 1177 1178 /* 1179 * Clip the readahead and readbehind ranges to exclude resident pages. 1180 */ 1181 if (rahead != NULL) { 1182 KASSERT(reqcount - 1 <= maxahead, 1183 ("page count %d extends beyond swap block", reqcount)); 1184 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1185 pindex = ma[reqcount - 1]->pindex; 1186 msucc = TAILQ_NEXT(ma[reqcount - 1], listq); 1187 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1188 *rahead = msucc->pindex - pindex - 1; 1189 } 1190 if (rbehind != NULL) { 1191 *rbehind = imin(*rbehind, maxbehind); 1192 pindex = ma[0]->pindex; 1193 mpred = TAILQ_PREV(ma[0], pglist, listq); 1194 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1195 *rbehind = pindex - mpred->pindex - 1; 1196 } 1197 1198 bm = ma[0]; 1199 for (i = 0; i < count; i++) 1200 ma[i]->oflags |= VPO_SWAPINPROG; 1201 1202 /* 1203 * Allocate readahead and readbehind pages. 1204 */ 1205 if (rbehind != NULL) { 1206 for (i = 1; i <= *rbehind; i++) { 1207 p = vm_page_alloc(object, ma[0]->pindex - i, 1208 VM_ALLOC_NORMAL); 1209 if (p == NULL) 1210 break; 1211 p->oflags |= VPO_SWAPINPROG; 1212 bm = p; 1213 } 1214 *rbehind = i - 1; 1215 } 1216 if (rahead != NULL) { 1217 for (i = 0; i < *rahead; i++) { 1218 p = vm_page_alloc(object, 1219 ma[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1220 if (p == NULL) 1221 break; 1222 p->oflags |= VPO_SWAPINPROG; 1223 } 1224 *rahead = i; 1225 } 1226 if (rbehind != NULL) 1227 count += *rbehind; 1228 if (rahead != NULL) 1229 count += *rahead; 1230 1231 vm_object_pip_add(object, count); 1232 1233 pindex = bm->pindex; 1234 blk = swp_pager_meta_lookup(object, pindex); 1235 KASSERT(blk != SWAPBLK_NONE, 1236 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1237 1238 VM_OBJECT_WUNLOCK(object); 1239 bp = uma_zalloc(swrbuf_zone, M_WAITOK); 1240 /* Pages cannot leave the object while busy. */ 1241 for (i = 0, p = bm; i < count; i++, p = TAILQ_NEXT(p, listq)) { 1242 MPASS(p->pindex == bm->pindex + i); 1243 bp->b_pages[i] = p; 1244 } 1245 1246 bp->b_flags |= B_PAGING; 1247 bp->b_iocmd = BIO_READ; 1248 bp->b_iodone = swp_pager_async_iodone; 1249 bp->b_rcred = crhold(thread0.td_ucred); 1250 bp->b_wcred = crhold(thread0.td_ucred); 1251 bp->b_blkno = blk; 1252 bp->b_bcount = PAGE_SIZE * count; 1253 bp->b_bufsize = PAGE_SIZE * count; 1254 bp->b_npages = count; 1255 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1256 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1257 1258 VM_CNT_INC(v_swapin); 1259 VM_CNT_ADD(v_swappgsin, count); 1260 1261 /* 1262 * perform the I/O. NOTE!!! bp cannot be considered valid after 1263 * this point because we automatically release it on completion. 1264 * Instead, we look at the one page we are interested in which we 1265 * still hold a lock on even through the I/O completion. 1266 * 1267 * The other pages in our ma[] array are also released on completion, 1268 * so we cannot assume they are valid anymore either. 1269 * 1270 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1271 */ 1272 BUF_KERNPROC(bp); 1273 swp_pager_strategy(bp); 1274 1275 /* 1276 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1277 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1278 * is set in the metadata for each page in the request. 1279 */ 1280 VM_OBJECT_WLOCK(object); 1281 while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) { 1282 ma[0]->oflags |= VPO_SWAPSLEEP; 1283 VM_CNT_INC(v_intrans); 1284 if (VM_OBJECT_SLEEP(object, &object->handle, PSWP, 1285 "swread", hz * 20)) { 1286 printf( 1287 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1288 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1289 } 1290 } 1291 1292 /* 1293 * If we had an unrecoverable read error pages will not be valid. 1294 */ 1295 for (i = 0; i < reqcount; i++) 1296 if (ma[i]->valid != VM_PAGE_BITS_ALL) 1297 return (VM_PAGER_ERROR); 1298 1299 return (VM_PAGER_OK); 1300 1301 /* 1302 * A final note: in a low swap situation, we cannot deallocate swap 1303 * and mark a page dirty here because the caller is likely to mark 1304 * the page clean when we return, causing the page to possibly revert 1305 * to all-zero's later. 1306 */ 1307 } 1308 1309 /* 1310 * swap_pager_getpages_async(): 1311 * 1312 * Right now this is emulation of asynchronous operation on top of 1313 * swap_pager_getpages(). 1314 */ 1315 static int 1316 swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count, 1317 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1318 { 1319 int r, error; 1320 1321 r = swap_pager_getpages(object, ma, count, rbehind, rahead); 1322 VM_OBJECT_WUNLOCK(object); 1323 switch (r) { 1324 case VM_PAGER_OK: 1325 error = 0; 1326 break; 1327 case VM_PAGER_ERROR: 1328 error = EIO; 1329 break; 1330 case VM_PAGER_FAIL: 1331 error = EINVAL; 1332 break; 1333 default: 1334 panic("unhandled swap_pager_getpages() error %d", r); 1335 } 1336 (iodone)(arg, ma, count, error); 1337 VM_OBJECT_WLOCK(object); 1338 1339 return (r); 1340 } 1341 1342 /* 1343 * swap_pager_putpages: 1344 * 1345 * Assign swap (if necessary) and initiate I/O on the specified pages. 1346 * 1347 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1348 * are automatically converted to SWAP objects. 1349 * 1350 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1351 * vm_page reservation system coupled with properly written VFS devices 1352 * should ensure that no low-memory deadlock occurs. This is an area 1353 * which needs work. 1354 * 1355 * The parent has N vm_object_pip_add() references prior to 1356 * calling us and will remove references for rtvals[] that are 1357 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1358 * completion. 1359 * 1360 * The parent has soft-busy'd the pages it passes us and will unbusy 1361 * those whose rtvals[] entry is not set to VM_PAGER_PEND on return. 1362 * We need to unbusy the rest on I/O completion. 1363 */ 1364 static void 1365 swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count, 1366 int flags, int *rtvals) 1367 { 1368 struct buf *bp; 1369 daddr_t addr, blk, n_free, s_free; 1370 vm_page_t mreq; 1371 int i, j, n; 1372 bool async; 1373 1374 KASSERT(count == 0 || ma[0]->object == object, 1375 ("%s: object mismatch %p/%p", 1376 __func__, object, ma[0]->object)); 1377 1378 /* 1379 * Step 1 1380 * 1381 * Turn object into OBJT_SWAP. Force sync if not a pageout process. 1382 */ 1383 if (object->type != OBJT_SWAP) { 1384 addr = swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1385 KASSERT(addr == SWAPBLK_NONE, 1386 ("unexpected object swap block")); 1387 } 1388 VM_OBJECT_WUNLOCK(object); 1389 async = curproc == pageproc && (flags & VM_PAGER_PUT_SYNC) == 0; 1390 swp_pager_init_freerange(&s_free, &n_free); 1391 1392 /* 1393 * Step 2 1394 * 1395 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1396 * The page is left dirty until the pageout operation completes 1397 * successfully. 1398 */ 1399 for (i = 0; i < count; i += n) { 1400 /* Maximum I/O size is limited by maximum swap block size. */ 1401 n = min(count - i, nsw_cluster_max); 1402 1403 /* Get a block of swap of size up to size n. */ 1404 blk = swp_pager_getswapspace(&n, 4); 1405 if (blk == SWAPBLK_NONE) { 1406 for (j = 0; j < n; ++j) 1407 rtvals[i + j] = VM_PAGER_FAIL; 1408 continue; 1409 } 1410 1411 /* 1412 * All I/O parameters have been satisfied. Build the I/O 1413 * request and assign the swap space. 1414 */ 1415 if (async) { 1416 mtx_lock(&swbuf_mtx); 1417 while (nsw_wcount_async == 0) 1418 msleep(&nsw_wcount_async, &swbuf_mtx, PVM, 1419 "swbufa", 0); 1420 nsw_wcount_async--; 1421 mtx_unlock(&swbuf_mtx); 1422 } 1423 bp = uma_zalloc(swwbuf_zone, M_WAITOK); 1424 if (async) 1425 bp->b_flags = B_ASYNC; 1426 bp->b_flags |= B_PAGING; 1427 bp->b_iocmd = BIO_WRITE; 1428 1429 bp->b_rcred = crhold(thread0.td_ucred); 1430 bp->b_wcred = crhold(thread0.td_ucred); 1431 bp->b_bcount = PAGE_SIZE * n; 1432 bp->b_bufsize = PAGE_SIZE * n; 1433 bp->b_blkno = blk; 1434 1435 VM_OBJECT_WLOCK(object); 1436 for (j = 0; j < n; ++j) { 1437 mreq = ma[i + j]; 1438 addr = swp_pager_meta_build(mreq->object, mreq->pindex, 1439 blk + j); 1440 if (addr != SWAPBLK_NONE) 1441 swp_pager_update_freerange(&s_free, &n_free, 1442 addr); 1443 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1444 mreq->oflags |= VPO_SWAPINPROG; 1445 bp->b_pages[j] = mreq; 1446 } 1447 VM_OBJECT_WUNLOCK(object); 1448 bp->b_npages = n; 1449 /* 1450 * Must set dirty range for NFS to work. 1451 */ 1452 bp->b_dirtyoff = 0; 1453 bp->b_dirtyend = bp->b_bcount; 1454 1455 VM_CNT_INC(v_swapout); 1456 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1457 1458 /* 1459 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1460 * can call the async completion routine at the end of a 1461 * synchronous I/O operation. Otherwise, our caller would 1462 * perform duplicate unbusy and wakeup operations on the page 1463 * and object, respectively. 1464 */ 1465 for (j = 0; j < n; j++) 1466 rtvals[i + j] = VM_PAGER_PEND; 1467 1468 /* 1469 * asynchronous 1470 * 1471 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1472 */ 1473 if (async) { 1474 bp->b_iodone = swp_pager_async_iodone; 1475 BUF_KERNPROC(bp); 1476 swp_pager_strategy(bp); 1477 continue; 1478 } 1479 1480 /* 1481 * synchronous 1482 * 1483 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1484 */ 1485 bp->b_iodone = bdone; 1486 swp_pager_strategy(bp); 1487 1488 /* 1489 * Wait for the sync I/O to complete. 1490 */ 1491 bwait(bp, PVM, "swwrt"); 1492 1493 /* 1494 * Now that we are through with the bp, we can call the 1495 * normal async completion, which frees everything up. 1496 */ 1497 swp_pager_async_iodone(bp); 1498 } 1499 swp_pager_freeswapspace(s_free, n_free); 1500 VM_OBJECT_WLOCK(object); 1501 } 1502 1503 /* 1504 * swp_pager_async_iodone: 1505 * 1506 * Completion routine for asynchronous reads and writes from/to swap. 1507 * Also called manually by synchronous code to finish up a bp. 1508 * 1509 * This routine may not sleep. 1510 */ 1511 static void 1512 swp_pager_async_iodone(struct buf *bp) 1513 { 1514 int i; 1515 vm_object_t object = NULL; 1516 1517 /* 1518 * Report error - unless we ran out of memory, in which case 1519 * we've already logged it in swapgeom_strategy(). 1520 */ 1521 if (bp->b_ioflags & BIO_ERROR && bp->b_error != ENOMEM) { 1522 printf( 1523 "swap_pager: I/O error - %s failed; blkno %ld," 1524 "size %ld, error %d\n", 1525 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1526 (long)bp->b_blkno, 1527 (long)bp->b_bcount, 1528 bp->b_error 1529 ); 1530 } 1531 1532 /* 1533 * remove the mapping for kernel virtual 1534 */ 1535 if (buf_mapped(bp)) 1536 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1537 else 1538 bp->b_data = bp->b_kvabase; 1539 1540 if (bp->b_npages) { 1541 object = bp->b_pages[0]->object; 1542 VM_OBJECT_WLOCK(object); 1543 } 1544 1545 /* 1546 * cleanup pages. If an error occurs writing to swap, we are in 1547 * very serious trouble. If it happens to be a disk error, though, 1548 * we may be able to recover by reassigning the swap later on. So 1549 * in this case we remove the m->swapblk assignment for the page 1550 * but do not free it in the rlist. The errornous block(s) are thus 1551 * never reallocated as swap. Redirty the page and continue. 1552 */ 1553 for (i = 0; i < bp->b_npages; ++i) { 1554 vm_page_t m = bp->b_pages[i]; 1555 1556 m->oflags &= ~VPO_SWAPINPROG; 1557 if (m->oflags & VPO_SWAPSLEEP) { 1558 m->oflags &= ~VPO_SWAPSLEEP; 1559 wakeup(&object->handle); 1560 } 1561 1562 if (bp->b_ioflags & BIO_ERROR) { 1563 /* 1564 * If an error occurs I'd love to throw the swapblk 1565 * away without freeing it back to swapspace, so it 1566 * can never be used again. But I can't from an 1567 * interrupt. 1568 */ 1569 if (bp->b_iocmd == BIO_READ) { 1570 /* 1571 * NOTE: for reads, m->dirty will probably 1572 * be overridden by the original caller of 1573 * getpages so don't play cute tricks here. 1574 */ 1575 vm_page_invalid(m); 1576 } else { 1577 /* 1578 * If a write error occurs, reactivate page 1579 * so it doesn't clog the inactive list, 1580 * then finish the I/O. 1581 */ 1582 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1583 vm_page_lock(m); 1584 vm_page_activate(m); 1585 vm_page_unlock(m); 1586 vm_page_sunbusy(m); 1587 } 1588 } else if (bp->b_iocmd == BIO_READ) { 1589 /* 1590 * NOTE: for reads, m->dirty will probably be 1591 * overridden by the original caller of getpages so 1592 * we cannot set them in order to free the underlying 1593 * swap in a low-swap situation. I don't think we'd 1594 * want to do that anyway, but it was an optimization 1595 * that existed in the old swapper for a time before 1596 * it got ripped out due to precisely this problem. 1597 */ 1598 KASSERT(!pmap_page_is_mapped(m), 1599 ("swp_pager_async_iodone: page %p is mapped", m)); 1600 KASSERT(m->dirty == 0, 1601 ("swp_pager_async_iodone: page %p is dirty", m)); 1602 1603 vm_page_valid(m); 1604 if (i < bp->b_pgbefore || 1605 i >= bp->b_npages - bp->b_pgafter) 1606 vm_page_readahead_finish(m); 1607 } else { 1608 /* 1609 * For write success, clear the dirty 1610 * status, then finish the I/O ( which decrements the 1611 * busy count and possibly wakes waiter's up ). 1612 * A page is only written to swap after a period of 1613 * inactivity. Therefore, we do not expect it to be 1614 * reused. 1615 */ 1616 KASSERT(!pmap_page_is_write_mapped(m), 1617 ("swp_pager_async_iodone: page %p is not write" 1618 " protected", m)); 1619 vm_page_undirty(m); 1620 vm_page_lock(m); 1621 vm_page_deactivate_noreuse(m); 1622 vm_page_unlock(m); 1623 vm_page_sunbusy(m); 1624 } 1625 } 1626 1627 /* 1628 * adjust pip. NOTE: the original parent may still have its own 1629 * pip refs on the object. 1630 */ 1631 if (object != NULL) { 1632 vm_object_pip_wakeupn(object, bp->b_npages); 1633 VM_OBJECT_WUNLOCK(object); 1634 } 1635 1636 /* 1637 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1638 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1639 * trigger a KASSERT in relpbuf(). 1640 */ 1641 if (bp->b_vp) { 1642 bp->b_vp = NULL; 1643 bp->b_bufobj = NULL; 1644 } 1645 /* 1646 * release the physical I/O buffer 1647 */ 1648 if (bp->b_flags & B_ASYNC) { 1649 mtx_lock(&swbuf_mtx); 1650 if (++nsw_wcount_async == 1) 1651 wakeup(&nsw_wcount_async); 1652 mtx_unlock(&swbuf_mtx); 1653 } 1654 uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp); 1655 } 1656 1657 int 1658 swap_pager_nswapdev(void) 1659 { 1660 1661 return (nswapdev); 1662 } 1663 1664 static void 1665 swp_pager_force_dirty(vm_page_t m) 1666 { 1667 1668 vm_page_dirty(m); 1669 #ifdef INVARIANTS 1670 vm_page_lock(m); 1671 if (!vm_page_wired(m) && m->queue == PQ_NONE) 1672 panic("page %p is neither wired nor queued", m); 1673 vm_page_unlock(m); 1674 #endif 1675 vm_page_xunbusy(m); 1676 swap_pager_unswapped(m); 1677 } 1678 1679 static void 1680 swp_pager_force_launder(vm_page_t m) 1681 { 1682 1683 vm_page_dirty(m); 1684 vm_page_lock(m); 1685 vm_page_launder(m); 1686 vm_page_unlock(m); 1687 vm_page_xunbusy(m); 1688 swap_pager_unswapped(m); 1689 } 1690 1691 /* 1692 * SWP_PAGER_FORCE_PAGEIN() - force swap blocks to be paged in 1693 * 1694 * This routine dissociates pages starting at the given index within an 1695 * object from their backing store, paging them in if they do not reside 1696 * in memory. Pages that are paged in are marked dirty and placed in the 1697 * laundry queue. Pages are marked dirty because they no longer have 1698 * backing store. They are placed in the laundry queue because they have 1699 * not been accessed recently. Otherwise, they would already reside in 1700 * memory. 1701 */ 1702 static void 1703 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex, int npages) 1704 { 1705 vm_page_t ma[npages]; 1706 int i, j; 1707 1708 KASSERT(npages > 0, ("%s: No pages", __func__)); 1709 KASSERT(npages <= MAXPHYS / PAGE_SIZE, 1710 ("%s: Too many pages: %d", __func__, npages)); 1711 KASSERT(object->type == OBJT_SWAP, 1712 ("%s: Object not swappable", __func__)); 1713 vm_object_pip_add(object, npages); 1714 vm_page_grab_pages(object, pindex, VM_ALLOC_NORMAL, ma, npages); 1715 for (i = j = 0;; i++) { 1716 /* Count nonresident pages, to page-in all at once. */ 1717 if (i < npages && ma[i]->valid != VM_PAGE_BITS_ALL) 1718 continue; 1719 if (j < i) { 1720 /* Page-in nonresident pages. Mark for laundering. */ 1721 if (swap_pager_getpages(object, &ma[j], i - j, NULL, 1722 NULL) != VM_PAGER_OK) 1723 panic("%s: read from swap failed", __func__); 1724 do { 1725 swp_pager_force_launder(ma[j]); 1726 } while (++j < i); 1727 } 1728 if (i == npages) 1729 break; 1730 /* Mark dirty a resident page. */ 1731 swp_pager_force_dirty(ma[j++]); 1732 } 1733 vm_object_pip_wakeupn(object, npages); 1734 } 1735 1736 /* 1737 * swap_pager_swapoff_object: 1738 * 1739 * Page in all of the pages that have been paged out for an object 1740 * to a swap device. 1741 */ 1742 static void 1743 swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object) 1744 { 1745 struct swblk *sb; 1746 vm_pindex_t pi, s_pindex; 1747 daddr_t blk, n_blks, s_blk; 1748 int i; 1749 1750 KASSERT(object->type == OBJT_SWAP, 1751 ("%s: Object not swappable", __func__)); 1752 n_blks = 0; 1753 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1754 &object->un_pager.swp.swp_blks, pi)) != NULL; ) { 1755 for (i = 0; i < SWAP_META_PAGES; i++) { 1756 blk = sb->d[i]; 1757 if (!swp_pager_isondev(blk, sp)) 1758 blk = SWAPBLK_NONE; 1759 1760 /* 1761 * If there are no blocks/pages accumulated, start a new 1762 * accumulation here. 1763 */ 1764 if (n_blks == 0) { 1765 if (blk != SWAPBLK_NONE) { 1766 s_blk = blk; 1767 s_pindex = sb->p + i; 1768 n_blks = 1; 1769 } 1770 continue; 1771 } 1772 1773 /* 1774 * If the accumulation can be extended without breaking 1775 * the sequence of consecutive blocks and pages that 1776 * swp_pager_force_pagein() depends on, do so. 1777 */ 1778 if (n_blks < MAXPHYS / PAGE_SIZE && 1779 s_blk + n_blks == blk && 1780 s_pindex + n_blks == sb->p + i) { 1781 ++n_blks; 1782 continue; 1783 } 1784 1785 /* 1786 * The sequence of consecutive blocks and pages cannot 1787 * be extended, so page them all in here. Then, 1788 * because doing so involves releasing and reacquiring 1789 * a lock that protects the swap block pctrie, do not 1790 * rely on the current swap block. Break this loop and 1791 * re-fetch the same pindex from the pctrie again. 1792 */ 1793 swp_pager_force_pagein(object, s_pindex, n_blks); 1794 n_blks = 0; 1795 break; 1796 } 1797 if (i == SWAP_META_PAGES) 1798 pi = sb->p + SWAP_META_PAGES; 1799 } 1800 if (n_blks > 0) 1801 swp_pager_force_pagein(object, s_pindex, n_blks); 1802 } 1803 1804 /* 1805 * swap_pager_swapoff: 1806 * 1807 * Page in all of the pages that have been paged out to the 1808 * given device. The corresponding blocks in the bitmap must be 1809 * marked as allocated and the device must be flagged SW_CLOSING. 1810 * There may be no processes swapped out to the device. 1811 * 1812 * This routine may block. 1813 */ 1814 static void 1815 swap_pager_swapoff(struct swdevt *sp) 1816 { 1817 vm_object_t object; 1818 int retries; 1819 1820 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 1821 1822 retries = 0; 1823 full_rescan: 1824 mtx_lock(&vm_object_list_mtx); 1825 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1826 if (object->type != OBJT_SWAP) 1827 continue; 1828 mtx_unlock(&vm_object_list_mtx); 1829 /* Depends on type-stability. */ 1830 VM_OBJECT_WLOCK(object); 1831 1832 /* 1833 * Dead objects are eventually terminated on their own. 1834 */ 1835 if ((object->flags & OBJ_DEAD) != 0) 1836 goto next_obj; 1837 1838 /* 1839 * Sync with fences placed after pctrie 1840 * initialization. We must not access pctrie below 1841 * unless we checked that our object is swap and not 1842 * dead. 1843 */ 1844 atomic_thread_fence_acq(); 1845 if (object->type != OBJT_SWAP) 1846 goto next_obj; 1847 1848 swap_pager_swapoff_object(sp, object); 1849 next_obj: 1850 VM_OBJECT_WUNLOCK(object); 1851 mtx_lock(&vm_object_list_mtx); 1852 } 1853 mtx_unlock(&vm_object_list_mtx); 1854 1855 if (sp->sw_used) { 1856 /* 1857 * Objects may be locked or paging to the device being 1858 * removed, so we will miss their pages and need to 1859 * make another pass. We have marked this device as 1860 * SW_CLOSING, so the activity should finish soon. 1861 */ 1862 retries++; 1863 if (retries > 100) { 1864 panic("swapoff: failed to locate %d swap blocks", 1865 sp->sw_used); 1866 } 1867 pause("swpoff", hz / 20); 1868 goto full_rescan; 1869 } 1870 EVENTHANDLER_INVOKE(swapoff, sp); 1871 } 1872 1873 /************************************************************************ 1874 * SWAP META DATA * 1875 ************************************************************************ 1876 * 1877 * These routines manipulate the swap metadata stored in the 1878 * OBJT_SWAP object. 1879 * 1880 * Swap metadata is implemented with a global hash and not directly 1881 * linked into the object. Instead the object simply contains 1882 * appropriate tracking counters. 1883 */ 1884 1885 /* 1886 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? 1887 */ 1888 static bool 1889 swp_pager_swblk_empty(struct swblk *sb, int start, int limit) 1890 { 1891 int i; 1892 1893 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); 1894 for (i = start; i < limit; i++) { 1895 if (sb->d[i] != SWAPBLK_NONE) 1896 return (false); 1897 } 1898 return (true); 1899 } 1900 1901 /* 1902 * SWP_PAGER_FREE_EMPTY_SWBLK() - frees if a block is free 1903 * 1904 * Nothing is done if the block is still in use. 1905 */ 1906 static void 1907 swp_pager_free_empty_swblk(vm_object_t object, struct swblk *sb) 1908 { 1909 1910 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 1911 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 1912 uma_zfree(swblk_zone, sb); 1913 } 1914 } 1915 1916 /* 1917 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1918 * 1919 * We first convert the object to a swap object if it is a default 1920 * object. 1921 * 1922 * The specified swapblk is added to the object's swap metadata. If 1923 * the swapblk is not valid, it is freed instead. Any previously 1924 * assigned swapblk is returned. 1925 */ 1926 static daddr_t 1927 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1928 { 1929 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 1930 struct swblk *sb, *sb1; 1931 vm_pindex_t modpi, rdpi; 1932 daddr_t prev_swapblk; 1933 int error, i; 1934 1935 VM_OBJECT_ASSERT_WLOCKED(object); 1936 1937 /* 1938 * Convert default object to swap object if necessary 1939 */ 1940 if (object->type != OBJT_SWAP) { 1941 pctrie_init(&object->un_pager.swp.swp_blks); 1942 1943 /* 1944 * Ensure that swap_pager_swapoff()'s iteration over 1945 * object_list does not see a garbage pctrie. 1946 */ 1947 atomic_thread_fence_rel(); 1948 1949 object->type = OBJT_SWAP; 1950 object->un_pager.swp.writemappings = 0; 1951 KASSERT(object->handle == NULL, ("default pager with handle")); 1952 } 1953 1954 rdpi = rounddown(pindex, SWAP_META_PAGES); 1955 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi); 1956 if (sb == NULL) { 1957 if (swapblk == SWAPBLK_NONE) 1958 return (SWAPBLK_NONE); 1959 for (;;) { 1960 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 1961 pageproc ? M_USE_RESERVE : 0)); 1962 if (sb != NULL) { 1963 sb->p = rdpi; 1964 for (i = 0; i < SWAP_META_PAGES; i++) 1965 sb->d[i] = SWAPBLK_NONE; 1966 if (atomic_cmpset_int(&swblk_zone_exhausted, 1967 1, 0)) 1968 printf("swblk zone ok\n"); 1969 break; 1970 } 1971 VM_OBJECT_WUNLOCK(object); 1972 if (uma_zone_exhausted(swblk_zone)) { 1973 if (atomic_cmpset_int(&swblk_zone_exhausted, 1974 0, 1)) 1975 printf("swap blk zone exhausted, " 1976 "increase kern.maxswzone\n"); 1977 vm_pageout_oom(VM_OOM_SWAPZ); 1978 pause("swzonxb", 10); 1979 } else 1980 uma_zwait(swblk_zone); 1981 VM_OBJECT_WLOCK(object); 1982 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 1983 rdpi); 1984 if (sb != NULL) 1985 /* 1986 * Somebody swapped out a nearby page, 1987 * allocating swblk at the rdpi index, 1988 * while we dropped the object lock. 1989 */ 1990 goto allocated; 1991 } 1992 for (;;) { 1993 error = SWAP_PCTRIE_INSERT( 1994 &object->un_pager.swp.swp_blks, sb); 1995 if (error == 0) { 1996 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1997 1, 0)) 1998 printf("swpctrie zone ok\n"); 1999 break; 2000 } 2001 VM_OBJECT_WUNLOCK(object); 2002 if (uma_zone_exhausted(swpctrie_zone)) { 2003 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2004 0, 1)) 2005 printf("swap pctrie zone exhausted, " 2006 "increase kern.maxswzone\n"); 2007 vm_pageout_oom(VM_OOM_SWAPZ); 2008 pause("swzonxp", 10); 2009 } else 2010 uma_zwait(swpctrie_zone); 2011 VM_OBJECT_WLOCK(object); 2012 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2013 rdpi); 2014 if (sb1 != NULL) { 2015 uma_zfree(swblk_zone, sb); 2016 sb = sb1; 2017 goto allocated; 2018 } 2019 } 2020 } 2021 allocated: 2022 MPASS(sb->p == rdpi); 2023 2024 modpi = pindex % SWAP_META_PAGES; 2025 /* Return prior contents of metadata. */ 2026 prev_swapblk = sb->d[modpi]; 2027 /* Enter block into metadata. */ 2028 sb->d[modpi] = swapblk; 2029 2030 /* 2031 * Free the swblk if we end up with the empty page run. 2032 */ 2033 if (swapblk == SWAPBLK_NONE) 2034 swp_pager_free_empty_swblk(object, sb); 2035 return (prev_swapblk); 2036 } 2037 2038 /* 2039 * SWP_PAGER_META_TRANSFER() - free a range of blocks in the srcobject's swap 2040 * metadata, or transfer it into dstobject. 2041 * 2042 * This routine will free swap metadata structures as they are cleaned 2043 * out. 2044 */ 2045 static void 2046 swp_pager_meta_transfer(vm_object_t srcobject, vm_object_t dstobject, 2047 vm_pindex_t pindex, vm_pindex_t count) 2048 { 2049 struct swblk *sb; 2050 daddr_t n_free, s_free; 2051 vm_pindex_t offset, last; 2052 int i, limit, start; 2053 2054 VM_OBJECT_ASSERT_WLOCKED(srcobject); 2055 if (srcobject->type != OBJT_SWAP || count == 0) 2056 return; 2057 2058 swp_pager_init_freerange(&s_free, &n_free); 2059 offset = pindex; 2060 last = pindex + count; 2061 for (;;) { 2062 sb = SWAP_PCTRIE_LOOKUP_GE(&srcobject->un_pager.swp.swp_blks, 2063 rounddown(pindex, SWAP_META_PAGES)); 2064 if (sb == NULL || sb->p >= last) 2065 break; 2066 start = pindex > sb->p ? pindex - sb->p : 0; 2067 limit = last - sb->p < SWAP_META_PAGES ? last - sb->p : 2068 SWAP_META_PAGES; 2069 for (i = start; i < limit; i++) { 2070 if (sb->d[i] == SWAPBLK_NONE) 2071 continue; 2072 if (dstobject == NULL || 2073 !swp_pager_xfer_source(srcobject, dstobject, 2074 sb->p + i - offset, sb->d[i])) { 2075 swp_pager_update_freerange(&s_free, &n_free, 2076 sb->d[i]); 2077 } 2078 sb->d[i] = SWAPBLK_NONE; 2079 } 2080 pindex = sb->p + SWAP_META_PAGES; 2081 if (swp_pager_swblk_empty(sb, 0, start) && 2082 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2083 SWAP_PCTRIE_REMOVE(&srcobject->un_pager.swp.swp_blks, 2084 sb->p); 2085 uma_zfree(swblk_zone, sb); 2086 } 2087 } 2088 swp_pager_freeswapspace(s_free, n_free); 2089 } 2090 2091 /* 2092 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2093 * 2094 * The requested range of blocks is freed, with any associated swap 2095 * returned to the swap bitmap. 2096 * 2097 * This routine will free swap metadata structures as they are cleaned 2098 * out. This routine does *NOT* operate on swap metadata associated 2099 * with resident pages. 2100 */ 2101 static void 2102 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count) 2103 { 2104 swp_pager_meta_transfer(object, NULL, pindex, count); 2105 } 2106 2107 /* 2108 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2109 * 2110 * This routine locates and destroys all swap metadata associated with 2111 * an object. 2112 */ 2113 static void 2114 swp_pager_meta_free_all(vm_object_t object) 2115 { 2116 struct swblk *sb; 2117 daddr_t n_free, s_free; 2118 vm_pindex_t pindex; 2119 int i; 2120 2121 VM_OBJECT_ASSERT_WLOCKED(object); 2122 if (object->type != OBJT_SWAP) 2123 return; 2124 2125 swp_pager_init_freerange(&s_free, &n_free); 2126 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 2127 &object->un_pager.swp.swp_blks, pindex)) != NULL;) { 2128 pindex = sb->p + SWAP_META_PAGES; 2129 for (i = 0; i < SWAP_META_PAGES; i++) { 2130 if (sb->d[i] == SWAPBLK_NONE) 2131 continue; 2132 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]); 2133 } 2134 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 2135 uma_zfree(swblk_zone, sb); 2136 } 2137 swp_pager_freeswapspace(s_free, n_free); 2138 } 2139 2140 /* 2141 * SWP_PAGER_METACTL() - misc control of swap meta data. 2142 * 2143 * This routine is capable of looking up, or removing swapblk 2144 * assignments in the swap meta data. It returns the swapblk being 2145 * looked-up, popped, or SWAPBLK_NONE if the block was invalid. 2146 * 2147 * When acting on a busy resident page and paging is in progress, we 2148 * have to wait until paging is complete but otherwise can act on the 2149 * busy page. 2150 */ 2151 static daddr_t 2152 swp_pager_meta_lookup(vm_object_t object, vm_pindex_t pindex) 2153 { 2154 struct swblk *sb; 2155 2156 VM_OBJECT_ASSERT_LOCKED(object); 2157 2158 /* 2159 * The meta data only exists if the object is OBJT_SWAP 2160 * and even then might not be allocated yet. 2161 */ 2162 KASSERT(object->type == OBJT_SWAP, 2163 ("Lookup object not swappable")); 2164 2165 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2166 rounddown(pindex, SWAP_META_PAGES)); 2167 if (sb == NULL) 2168 return (SWAPBLK_NONE); 2169 return (sb->d[pindex % SWAP_META_PAGES]); 2170 } 2171 2172 /* 2173 * Returns the least page index which is greater than or equal to the 2174 * parameter pindex and for which there is a swap block allocated. 2175 * Returns object's size if the object's type is not swap or if there 2176 * are no allocated swap blocks for the object after the requested 2177 * pindex. 2178 */ 2179 vm_pindex_t 2180 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2181 { 2182 struct swblk *sb; 2183 int i; 2184 2185 VM_OBJECT_ASSERT_LOCKED(object); 2186 if (object->type != OBJT_SWAP) 2187 return (object->size); 2188 2189 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2190 rounddown(pindex, SWAP_META_PAGES)); 2191 if (sb == NULL) 2192 return (object->size); 2193 if (sb->p < pindex) { 2194 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2195 if (sb->d[i] != SWAPBLK_NONE) 2196 return (sb->p + i); 2197 } 2198 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2199 roundup(pindex, SWAP_META_PAGES)); 2200 if (sb == NULL) 2201 return (object->size); 2202 } 2203 for (i = 0; i < SWAP_META_PAGES; i++) { 2204 if (sb->d[i] != SWAPBLK_NONE) 2205 return (sb->p + i); 2206 } 2207 2208 /* 2209 * We get here if a swblk is present in the trie but it 2210 * doesn't map any blocks. 2211 */ 2212 MPASS(0); 2213 return (object->size); 2214 } 2215 2216 /* 2217 * System call swapon(name) enables swapping on device name, 2218 * which must be in the swdevsw. Return EBUSY 2219 * if already swapping on this device. 2220 */ 2221 #ifndef _SYS_SYSPROTO_H_ 2222 struct swapon_args { 2223 char *name; 2224 }; 2225 #endif 2226 2227 /* 2228 * MPSAFE 2229 */ 2230 /* ARGSUSED */ 2231 int 2232 sys_swapon(struct thread *td, struct swapon_args *uap) 2233 { 2234 struct vattr attr; 2235 struct vnode *vp; 2236 struct nameidata nd; 2237 int error; 2238 2239 error = priv_check(td, PRIV_SWAPON); 2240 if (error) 2241 return (error); 2242 2243 sx_xlock(&swdev_syscall_lock); 2244 2245 /* 2246 * Swap metadata may not fit in the KVM if we have physical 2247 * memory of >1GB. 2248 */ 2249 if (swblk_zone == NULL) { 2250 error = ENOMEM; 2251 goto done; 2252 } 2253 2254 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2255 uap->name, td); 2256 error = namei(&nd); 2257 if (error) 2258 goto done; 2259 2260 NDFREE(&nd, NDF_ONLY_PNBUF); 2261 vp = nd.ni_vp; 2262 2263 if (vn_isdisk(vp, &error)) { 2264 error = swapongeom(vp); 2265 } else if (vp->v_type == VREG && 2266 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2267 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2268 /* 2269 * Allow direct swapping to NFS regular files in the same 2270 * way that nfs_mountroot() sets up diskless swapping. 2271 */ 2272 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2273 } 2274 2275 if (error) 2276 vrele(vp); 2277 done: 2278 sx_xunlock(&swdev_syscall_lock); 2279 return (error); 2280 } 2281 2282 /* 2283 * Check that the total amount of swap currently configured does not 2284 * exceed half the theoretical maximum. If it does, print a warning 2285 * message. 2286 */ 2287 static void 2288 swapon_check_swzone(void) 2289 { 2290 2291 /* recommend using no more than half that amount */ 2292 if (swap_total > swap_maxpages / 2) { 2293 printf("warning: total configured swap (%lu pages) " 2294 "exceeds maximum recommended amount (%lu pages).\n", 2295 swap_total, swap_maxpages / 2); 2296 printf("warning: increase kern.maxswzone " 2297 "or reduce amount of swap.\n"); 2298 } 2299 } 2300 2301 static void 2302 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2303 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2304 { 2305 struct swdevt *sp, *tsp; 2306 swblk_t dvbase; 2307 u_long mblocks; 2308 2309 /* 2310 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2311 * First chop nblks off to page-align it, then convert. 2312 * 2313 * sw->sw_nblks is in page-sized chunks now too. 2314 */ 2315 nblks &= ~(ctodb(1) - 1); 2316 nblks = dbtoc(nblks); 2317 2318 /* 2319 * If we go beyond this, we get overflows in the radix 2320 * tree bitmap code. 2321 */ 2322 mblocks = 0x40000000 / BLIST_META_RADIX; 2323 if (nblks > mblocks) { 2324 printf( 2325 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2326 mblocks / 1024 / 1024 * PAGE_SIZE); 2327 nblks = mblocks; 2328 } 2329 2330 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2331 sp->sw_vp = vp; 2332 sp->sw_id = id; 2333 sp->sw_dev = dev; 2334 sp->sw_nblks = nblks; 2335 sp->sw_used = 0; 2336 sp->sw_strategy = strategy; 2337 sp->sw_close = close; 2338 sp->sw_flags = flags; 2339 2340 sp->sw_blist = blist_create(nblks, M_WAITOK); 2341 /* 2342 * Do not free the first blocks in order to avoid overwriting 2343 * any bsd label at the front of the partition 2344 */ 2345 blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE), 2346 nblks - howmany(BBSIZE, PAGE_SIZE)); 2347 2348 dvbase = 0; 2349 mtx_lock(&sw_dev_mtx); 2350 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2351 if (tsp->sw_end >= dvbase) { 2352 /* 2353 * We put one uncovered page between the devices 2354 * in order to definitively prevent any cross-device 2355 * I/O requests 2356 */ 2357 dvbase = tsp->sw_end + 1; 2358 } 2359 } 2360 sp->sw_first = dvbase; 2361 sp->sw_end = dvbase + nblks; 2362 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2363 nswapdev++; 2364 swap_pager_avail += nblks - howmany(BBSIZE, PAGE_SIZE); 2365 swap_total += nblks; 2366 swapon_check_swzone(); 2367 swp_sizecheck(); 2368 mtx_unlock(&sw_dev_mtx); 2369 EVENTHANDLER_INVOKE(swapon, sp); 2370 } 2371 2372 /* 2373 * SYSCALL: swapoff(devname) 2374 * 2375 * Disable swapping on the given device. 2376 * 2377 * XXX: Badly designed system call: it should use a device index 2378 * rather than filename as specification. We keep sw_vp around 2379 * only to make this work. 2380 */ 2381 #ifndef _SYS_SYSPROTO_H_ 2382 struct swapoff_args { 2383 char *name; 2384 }; 2385 #endif 2386 2387 /* 2388 * MPSAFE 2389 */ 2390 /* ARGSUSED */ 2391 int 2392 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2393 { 2394 struct vnode *vp; 2395 struct nameidata nd; 2396 struct swdevt *sp; 2397 int error; 2398 2399 error = priv_check(td, PRIV_SWAPOFF); 2400 if (error) 2401 return (error); 2402 2403 sx_xlock(&swdev_syscall_lock); 2404 2405 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2406 td); 2407 error = namei(&nd); 2408 if (error) 2409 goto done; 2410 NDFREE(&nd, NDF_ONLY_PNBUF); 2411 vp = nd.ni_vp; 2412 2413 mtx_lock(&sw_dev_mtx); 2414 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2415 if (sp->sw_vp == vp) 2416 break; 2417 } 2418 mtx_unlock(&sw_dev_mtx); 2419 if (sp == NULL) { 2420 error = EINVAL; 2421 goto done; 2422 } 2423 error = swapoff_one(sp, td->td_ucred); 2424 done: 2425 sx_xunlock(&swdev_syscall_lock); 2426 return (error); 2427 } 2428 2429 static int 2430 swapoff_one(struct swdevt *sp, struct ucred *cred) 2431 { 2432 u_long nblks; 2433 #ifdef MAC 2434 int error; 2435 #endif 2436 2437 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2438 #ifdef MAC 2439 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2440 error = mac_system_check_swapoff(cred, sp->sw_vp); 2441 (void) VOP_UNLOCK(sp->sw_vp, 0); 2442 if (error != 0) 2443 return (error); 2444 #endif 2445 nblks = sp->sw_nblks; 2446 2447 /* 2448 * We can turn off this swap device safely only if the 2449 * available virtual memory in the system will fit the amount 2450 * of data we will have to page back in, plus an epsilon so 2451 * the system doesn't become critically low on swap space. 2452 */ 2453 if (vm_free_count() + swap_pager_avail < nblks + nswap_lowat) 2454 return (ENOMEM); 2455 2456 /* 2457 * Prevent further allocations on this device. 2458 */ 2459 mtx_lock(&sw_dev_mtx); 2460 sp->sw_flags |= SW_CLOSING; 2461 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2462 swap_total -= nblks; 2463 mtx_unlock(&sw_dev_mtx); 2464 2465 /* 2466 * Page in the contents of the device and close it. 2467 */ 2468 swap_pager_swapoff(sp); 2469 2470 sp->sw_close(curthread, sp); 2471 mtx_lock(&sw_dev_mtx); 2472 sp->sw_id = NULL; 2473 TAILQ_REMOVE(&swtailq, sp, sw_list); 2474 nswapdev--; 2475 if (nswapdev == 0) { 2476 swap_pager_full = 2; 2477 swap_pager_almost_full = 1; 2478 } 2479 if (swdevhd == sp) 2480 swdevhd = NULL; 2481 mtx_unlock(&sw_dev_mtx); 2482 blist_destroy(sp->sw_blist); 2483 free(sp, M_VMPGDATA); 2484 return (0); 2485 } 2486 2487 void 2488 swapoff_all(void) 2489 { 2490 struct swdevt *sp, *spt; 2491 const char *devname; 2492 int error; 2493 2494 sx_xlock(&swdev_syscall_lock); 2495 2496 mtx_lock(&sw_dev_mtx); 2497 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2498 mtx_unlock(&sw_dev_mtx); 2499 if (vn_isdisk(sp->sw_vp, NULL)) 2500 devname = devtoname(sp->sw_vp->v_rdev); 2501 else 2502 devname = "[file]"; 2503 error = swapoff_one(sp, thread0.td_ucred); 2504 if (error != 0) { 2505 printf("Cannot remove swap device %s (error=%d), " 2506 "skipping.\n", devname, error); 2507 } else if (bootverbose) { 2508 printf("Swap device %s removed.\n", devname); 2509 } 2510 mtx_lock(&sw_dev_mtx); 2511 } 2512 mtx_unlock(&sw_dev_mtx); 2513 2514 sx_xunlock(&swdev_syscall_lock); 2515 } 2516 2517 void 2518 swap_pager_status(int *total, int *used) 2519 { 2520 struct swdevt *sp; 2521 2522 *total = 0; 2523 *used = 0; 2524 mtx_lock(&sw_dev_mtx); 2525 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2526 *total += sp->sw_nblks; 2527 *used += sp->sw_used; 2528 } 2529 mtx_unlock(&sw_dev_mtx); 2530 } 2531 2532 int 2533 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2534 { 2535 struct swdevt *sp; 2536 const char *tmp_devname; 2537 int error, n; 2538 2539 n = 0; 2540 error = ENOENT; 2541 mtx_lock(&sw_dev_mtx); 2542 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2543 if (n != name) { 2544 n++; 2545 continue; 2546 } 2547 xs->xsw_version = XSWDEV_VERSION; 2548 xs->xsw_dev = sp->sw_dev; 2549 xs->xsw_flags = sp->sw_flags; 2550 xs->xsw_nblks = sp->sw_nblks; 2551 xs->xsw_used = sp->sw_used; 2552 if (devname != NULL) { 2553 if (vn_isdisk(sp->sw_vp, NULL)) 2554 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2555 else 2556 tmp_devname = "[file]"; 2557 strncpy(devname, tmp_devname, len); 2558 } 2559 error = 0; 2560 break; 2561 } 2562 mtx_unlock(&sw_dev_mtx); 2563 return (error); 2564 } 2565 2566 #if defined(COMPAT_FREEBSD11) 2567 #define XSWDEV_VERSION_11 1 2568 struct xswdev11 { 2569 u_int xsw_version; 2570 uint32_t xsw_dev; 2571 int xsw_flags; 2572 int xsw_nblks; 2573 int xsw_used; 2574 }; 2575 #endif 2576 2577 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2578 struct xswdev32 { 2579 u_int xsw_version; 2580 u_int xsw_dev1, xsw_dev2; 2581 int xsw_flags; 2582 int xsw_nblks; 2583 int xsw_used; 2584 }; 2585 #endif 2586 2587 static int 2588 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2589 { 2590 struct xswdev xs; 2591 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2592 struct xswdev32 xs32; 2593 #endif 2594 #if defined(COMPAT_FREEBSD11) 2595 struct xswdev11 xs11; 2596 #endif 2597 int error; 2598 2599 if (arg2 != 1) /* name length */ 2600 return (EINVAL); 2601 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2602 if (error != 0) 2603 return (error); 2604 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2605 if (req->oldlen == sizeof(xs32)) { 2606 xs32.xsw_version = XSWDEV_VERSION; 2607 xs32.xsw_dev1 = xs.xsw_dev; 2608 xs32.xsw_dev2 = xs.xsw_dev >> 32; 2609 xs32.xsw_flags = xs.xsw_flags; 2610 xs32.xsw_nblks = xs.xsw_nblks; 2611 xs32.xsw_used = xs.xsw_used; 2612 error = SYSCTL_OUT(req, &xs32, sizeof(xs32)); 2613 return (error); 2614 } 2615 #endif 2616 #if defined(COMPAT_FREEBSD11) 2617 if (req->oldlen == sizeof(xs11)) { 2618 xs11.xsw_version = XSWDEV_VERSION_11; 2619 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2620 xs11.xsw_flags = xs.xsw_flags; 2621 xs11.xsw_nblks = xs.xsw_nblks; 2622 xs11.xsw_used = xs.xsw_used; 2623 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2624 return (error); 2625 } 2626 #endif 2627 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2628 return (error); 2629 } 2630 2631 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2632 "Number of swap devices"); 2633 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2634 sysctl_vm_swap_info, 2635 "Swap statistics by device"); 2636 2637 /* 2638 * Count the approximate swap usage in pages for a vmspace. The 2639 * shadowed or not yet copied on write swap blocks are not accounted. 2640 * The map must be locked. 2641 */ 2642 long 2643 vmspace_swap_count(struct vmspace *vmspace) 2644 { 2645 vm_map_t map; 2646 vm_map_entry_t cur; 2647 vm_object_t object; 2648 struct swblk *sb; 2649 vm_pindex_t e, pi; 2650 long count; 2651 int i; 2652 2653 map = &vmspace->vm_map; 2654 count = 0; 2655 2656 VM_MAP_ENTRY_FOREACH(cur, map) { 2657 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 2658 continue; 2659 object = cur->object.vm_object; 2660 if (object == NULL || object->type != OBJT_SWAP) 2661 continue; 2662 VM_OBJECT_RLOCK(object); 2663 if (object->type != OBJT_SWAP) 2664 goto unlock; 2665 pi = OFF_TO_IDX(cur->offset); 2666 e = pi + OFF_TO_IDX(cur->end - cur->start); 2667 for (;; pi = sb->p + SWAP_META_PAGES) { 2668 sb = SWAP_PCTRIE_LOOKUP_GE( 2669 &object->un_pager.swp.swp_blks, pi); 2670 if (sb == NULL || sb->p >= e) 2671 break; 2672 for (i = 0; i < SWAP_META_PAGES; i++) { 2673 if (sb->p + i < e && 2674 sb->d[i] != SWAPBLK_NONE) 2675 count++; 2676 } 2677 } 2678 unlock: 2679 VM_OBJECT_RUNLOCK(object); 2680 } 2681 return (count); 2682 } 2683 2684 /* 2685 * GEOM backend 2686 * 2687 * Swapping onto disk devices. 2688 * 2689 */ 2690 2691 static g_orphan_t swapgeom_orphan; 2692 2693 static struct g_class g_swap_class = { 2694 .name = "SWAP", 2695 .version = G_VERSION, 2696 .orphan = swapgeom_orphan, 2697 }; 2698 2699 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2700 2701 2702 static void 2703 swapgeom_close_ev(void *arg, int flags) 2704 { 2705 struct g_consumer *cp; 2706 2707 cp = arg; 2708 g_access(cp, -1, -1, 0); 2709 g_detach(cp); 2710 g_destroy_consumer(cp); 2711 } 2712 2713 /* 2714 * Add a reference to the g_consumer for an inflight transaction. 2715 */ 2716 static void 2717 swapgeom_acquire(struct g_consumer *cp) 2718 { 2719 2720 mtx_assert(&sw_dev_mtx, MA_OWNED); 2721 cp->index++; 2722 } 2723 2724 /* 2725 * Remove a reference from the g_consumer. Post a close event if all 2726 * references go away, since the function might be called from the 2727 * biodone context. 2728 */ 2729 static void 2730 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2731 { 2732 2733 mtx_assert(&sw_dev_mtx, MA_OWNED); 2734 cp->index--; 2735 if (cp->index == 0) { 2736 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2737 sp->sw_id = NULL; 2738 } 2739 } 2740 2741 static void 2742 swapgeom_done(struct bio *bp2) 2743 { 2744 struct swdevt *sp; 2745 struct buf *bp; 2746 struct g_consumer *cp; 2747 2748 bp = bp2->bio_caller2; 2749 cp = bp2->bio_from; 2750 bp->b_ioflags = bp2->bio_flags; 2751 if (bp2->bio_error) 2752 bp->b_ioflags |= BIO_ERROR; 2753 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2754 bp->b_error = bp2->bio_error; 2755 bp->b_caller1 = NULL; 2756 bufdone(bp); 2757 sp = bp2->bio_caller1; 2758 mtx_lock(&sw_dev_mtx); 2759 swapgeom_release(cp, sp); 2760 mtx_unlock(&sw_dev_mtx); 2761 g_destroy_bio(bp2); 2762 } 2763 2764 static void 2765 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2766 { 2767 struct bio *bio; 2768 struct g_consumer *cp; 2769 2770 mtx_lock(&sw_dev_mtx); 2771 cp = sp->sw_id; 2772 if (cp == NULL) { 2773 mtx_unlock(&sw_dev_mtx); 2774 bp->b_error = ENXIO; 2775 bp->b_ioflags |= BIO_ERROR; 2776 bufdone(bp); 2777 return; 2778 } 2779 swapgeom_acquire(cp); 2780 mtx_unlock(&sw_dev_mtx); 2781 if (bp->b_iocmd == BIO_WRITE) 2782 bio = g_new_bio(); 2783 else 2784 bio = g_alloc_bio(); 2785 if (bio == NULL) { 2786 mtx_lock(&sw_dev_mtx); 2787 swapgeom_release(cp, sp); 2788 mtx_unlock(&sw_dev_mtx); 2789 bp->b_error = ENOMEM; 2790 bp->b_ioflags |= BIO_ERROR; 2791 printf("swap_pager: cannot allocate bio\n"); 2792 bufdone(bp); 2793 return; 2794 } 2795 2796 bp->b_caller1 = bio; 2797 bio->bio_caller1 = sp; 2798 bio->bio_caller2 = bp; 2799 bio->bio_cmd = bp->b_iocmd; 2800 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2801 bio->bio_length = bp->b_bcount; 2802 bio->bio_done = swapgeom_done; 2803 if (!buf_mapped(bp)) { 2804 bio->bio_ma = bp->b_pages; 2805 bio->bio_data = unmapped_buf; 2806 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2807 bio->bio_ma_n = bp->b_npages; 2808 bio->bio_flags |= BIO_UNMAPPED; 2809 } else { 2810 bio->bio_data = bp->b_data; 2811 bio->bio_ma = NULL; 2812 } 2813 g_io_request(bio, cp); 2814 return; 2815 } 2816 2817 static void 2818 swapgeom_orphan(struct g_consumer *cp) 2819 { 2820 struct swdevt *sp; 2821 int destroy; 2822 2823 mtx_lock(&sw_dev_mtx); 2824 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2825 if (sp->sw_id == cp) { 2826 sp->sw_flags |= SW_CLOSING; 2827 break; 2828 } 2829 } 2830 /* 2831 * Drop reference we were created with. Do directly since we're in a 2832 * special context where we don't have to queue the call to 2833 * swapgeom_close_ev(). 2834 */ 2835 cp->index--; 2836 destroy = ((sp != NULL) && (cp->index == 0)); 2837 if (destroy) 2838 sp->sw_id = NULL; 2839 mtx_unlock(&sw_dev_mtx); 2840 if (destroy) 2841 swapgeom_close_ev(cp, 0); 2842 } 2843 2844 static void 2845 swapgeom_close(struct thread *td, struct swdevt *sw) 2846 { 2847 struct g_consumer *cp; 2848 2849 mtx_lock(&sw_dev_mtx); 2850 cp = sw->sw_id; 2851 sw->sw_id = NULL; 2852 mtx_unlock(&sw_dev_mtx); 2853 2854 /* 2855 * swapgeom_close() may be called from the biodone context, 2856 * where we cannot perform topology changes. Delegate the 2857 * work to the events thread. 2858 */ 2859 if (cp != NULL) 2860 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2861 } 2862 2863 static int 2864 swapongeom_locked(struct cdev *dev, struct vnode *vp) 2865 { 2866 struct g_provider *pp; 2867 struct g_consumer *cp; 2868 static struct g_geom *gp; 2869 struct swdevt *sp; 2870 u_long nblks; 2871 int error; 2872 2873 pp = g_dev_getprovider(dev); 2874 if (pp == NULL) 2875 return (ENODEV); 2876 mtx_lock(&sw_dev_mtx); 2877 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2878 cp = sp->sw_id; 2879 if (cp != NULL && cp->provider == pp) { 2880 mtx_unlock(&sw_dev_mtx); 2881 return (EBUSY); 2882 } 2883 } 2884 mtx_unlock(&sw_dev_mtx); 2885 if (gp == NULL) 2886 gp = g_new_geomf(&g_swap_class, "swap"); 2887 cp = g_new_consumer(gp); 2888 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2889 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2890 g_attach(cp, pp); 2891 /* 2892 * XXX: Every time you think you can improve the margin for 2893 * footshooting, somebody depends on the ability to do so: 2894 * savecore(8) wants to write to our swapdev so we cannot 2895 * set an exclusive count :-( 2896 */ 2897 error = g_access(cp, 1, 1, 0); 2898 if (error != 0) { 2899 g_detach(cp); 2900 g_destroy_consumer(cp); 2901 return (error); 2902 } 2903 nblks = pp->mediasize / DEV_BSIZE; 2904 swaponsomething(vp, cp, nblks, swapgeom_strategy, 2905 swapgeom_close, dev2udev(dev), 2906 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2907 return (0); 2908 } 2909 2910 static int 2911 swapongeom(struct vnode *vp) 2912 { 2913 int error; 2914 2915 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2916 if (vp->v_type != VCHR || (vp->v_iflag & VI_DOOMED) != 0) { 2917 error = ENOENT; 2918 } else { 2919 g_topology_lock(); 2920 error = swapongeom_locked(vp->v_rdev, vp); 2921 g_topology_unlock(); 2922 } 2923 VOP_UNLOCK(vp, 0); 2924 return (error); 2925 } 2926 2927 /* 2928 * VNODE backend 2929 * 2930 * This is used mainly for network filesystem (read: probably only tested 2931 * with NFS) swapfiles. 2932 * 2933 */ 2934 2935 static void 2936 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2937 { 2938 struct vnode *vp2; 2939 2940 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2941 2942 vp2 = sp->sw_id; 2943 vhold(vp2); 2944 if (bp->b_iocmd == BIO_WRITE) { 2945 if (bp->b_bufobj) 2946 bufobj_wdrop(bp->b_bufobj); 2947 bufobj_wref(&vp2->v_bufobj); 2948 } 2949 if (bp->b_bufobj != &vp2->v_bufobj) 2950 bp->b_bufobj = &vp2->v_bufobj; 2951 bp->b_vp = vp2; 2952 bp->b_iooffset = dbtob(bp->b_blkno); 2953 bstrategy(bp); 2954 return; 2955 } 2956 2957 static void 2958 swapdev_close(struct thread *td, struct swdevt *sp) 2959 { 2960 2961 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2962 vrele(sp->sw_vp); 2963 } 2964 2965 2966 static int 2967 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2968 { 2969 struct swdevt *sp; 2970 int error; 2971 2972 if (nblks == 0) 2973 return (ENXIO); 2974 mtx_lock(&sw_dev_mtx); 2975 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2976 if (sp->sw_id == vp) { 2977 mtx_unlock(&sw_dev_mtx); 2978 return (EBUSY); 2979 } 2980 } 2981 mtx_unlock(&sw_dev_mtx); 2982 2983 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2984 #ifdef MAC 2985 error = mac_system_check_swapon(td->td_ucred, vp); 2986 if (error == 0) 2987 #endif 2988 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 2989 (void) VOP_UNLOCK(vp, 0); 2990 if (error) 2991 return (error); 2992 2993 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 2994 NODEV, 0); 2995 return (0); 2996 } 2997 2998 static int 2999 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 3000 { 3001 int error, new, n; 3002 3003 new = nsw_wcount_async_max; 3004 error = sysctl_handle_int(oidp, &new, 0, req); 3005 if (error != 0 || req->newptr == NULL) 3006 return (error); 3007 3008 if (new > nswbuf / 2 || new < 1) 3009 return (EINVAL); 3010 3011 mtx_lock(&swbuf_mtx); 3012 while (nsw_wcount_async_max != new) { 3013 /* 3014 * Adjust difference. If the current async count is too low, 3015 * we will need to sqeeze our update slowly in. Sleep with a 3016 * higher priority than getpbuf() to finish faster. 3017 */ 3018 n = new - nsw_wcount_async_max; 3019 if (nsw_wcount_async + n >= 0) { 3020 nsw_wcount_async += n; 3021 nsw_wcount_async_max += n; 3022 wakeup(&nsw_wcount_async); 3023 } else { 3024 nsw_wcount_async_max -= nsw_wcount_async; 3025 nsw_wcount_async = 0; 3026 msleep(&nsw_wcount_async, &swbuf_mtx, PSWP, 3027 "swpsysctl", 0); 3028 } 3029 } 3030 mtx_unlock(&swbuf_mtx); 3031 3032 return (0); 3033 } 3034 3035 static void 3036 swap_pager_update_writecount(vm_object_t object, vm_offset_t start, 3037 vm_offset_t end) 3038 { 3039 3040 VM_OBJECT_WLOCK(object); 3041 KASSERT((object->flags & OBJ_ANON) == 0, 3042 ("Splittable object with writecount")); 3043 object->un_pager.swp.writemappings += (vm_ooffset_t)end - start; 3044 VM_OBJECT_WUNLOCK(object); 3045 } 3046 3047 static void 3048 swap_pager_release_writecount(vm_object_t object, vm_offset_t start, 3049 vm_offset_t end) 3050 { 3051 3052 VM_OBJECT_WLOCK(object); 3053 KASSERT((object->flags & OBJ_ANON) == 0, 3054 ("Splittable object with writecount")); 3055 object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start; 3056 VM_OBJECT_WUNLOCK(object); 3057 } 3058