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 68 #include <sys/cdefs.h> 69 #include "opt_vm.h" 70 71 #include <sys/param.h> 72 #include <sys/bio.h> 73 #include <sys/blist.h> 74 #include <sys/buf.h> 75 #include <sys/conf.h> 76 #include <sys/disk.h> 77 #include <sys/disklabel.h> 78 #include <sys/eventhandler.h> 79 #include <sys/fcntl.h> 80 #include <sys/limits.h> 81 #include <sys/lock.h> 82 #include <sys/kernel.h> 83 #include <sys/mount.h> 84 #include <sys/namei.h> 85 #include <sys/malloc.h> 86 #include <sys/pctrie.h> 87 #include <sys/priv.h> 88 #include <sys/proc.h> 89 #include <sys/racct.h> 90 #include <sys/resource.h> 91 #include <sys/resourcevar.h> 92 #include <sys/rwlock.h> 93 #include <sys/sbuf.h> 94 #include <sys/sysctl.h> 95 #include <sys/sysproto.h> 96 #include <sys/systm.h> 97 #include <sys/sx.h> 98 #include <sys/unistd.h> 99 #include <sys/user.h> 100 #include <sys/vmmeter.h> 101 #include <sys/vnode.h> 102 103 #include <security/mac/mac_framework.h> 104 105 #include <vm/vm.h> 106 #include <vm/pmap.h> 107 #include <vm/vm_map.h> 108 #include <vm/vm_kern.h> 109 #include <vm/vm_object.h> 110 #include <vm/vm_page.h> 111 #include <vm/vm_pager.h> 112 #include <vm/vm_pageout.h> 113 #include <vm/vm_param.h> 114 #include <vm/swap_pager.h> 115 #include <vm/vm_extern.h> 116 #include <vm/uma.h> 117 118 #include <geom/geom.h> 119 120 /* 121 * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64. 122 * The 64-page limit is due to the radix code (kern/subr_blist.c). 123 */ 124 #ifndef MAX_PAGEOUT_CLUSTER 125 #define MAX_PAGEOUT_CLUSTER 32 126 #endif 127 128 #if !defined(SWB_NPAGES) 129 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER 130 #endif 131 132 #define SWAP_META_PAGES PCTRIE_COUNT 133 134 /* 135 * A swblk structure maps each page index within a 136 * SWAP_META_PAGES-aligned and sized range to the address of an 137 * on-disk swap block (or SWAPBLK_NONE). The collection of these 138 * mappings for an entire vm object is implemented as a pc-trie. 139 */ 140 struct swblk { 141 vm_pindex_t p; 142 daddr_t d[SWAP_META_PAGES]; 143 }; 144 145 /* 146 * A page_range structure records the start address and length of a sequence of 147 * mapped page addresses. 148 */ 149 struct page_range { 150 daddr_t start; 151 daddr_t num; 152 }; 153 154 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); 155 static struct mtx sw_dev_mtx; 156 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 157 static struct swdevt *swdevhd; /* Allocate from here next */ 158 static int nswapdev; /* Number of swap devices */ 159 int swap_pager_avail; 160 static struct sx swdev_syscall_lock; /* serialize swap(on|off) */ 161 162 static __exclusive_cache_line u_long swap_reserved; 163 static u_long swap_total; 164 static int sysctl_page_shift(SYSCTL_HANDLER_ARGS); 165 166 static SYSCTL_NODE(_vm_stats, OID_AUTO, swap, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 167 "VM swap stats"); 168 169 SYSCTL_PROC(_vm, OID_AUTO, swap_reserved, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 170 &swap_reserved, 0, sysctl_page_shift, "QU", 171 "Amount of swap storage needed to back all allocated anonymous memory."); 172 SYSCTL_PROC(_vm, OID_AUTO, swap_total, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 173 &swap_total, 0, sysctl_page_shift, "QU", 174 "Total amount of available swap storage."); 175 176 int vm_overcommit __read_mostly = 0; 177 SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &vm_overcommit, 0, 178 "Configure virtual memory overcommit behavior. See tuning(7) " 179 "for details."); 180 static unsigned long swzone; 181 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 182 "Actual size of swap metadata zone"); 183 static unsigned long swap_maxpages; 184 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, 185 "Maximum amount of swap supported"); 186 187 static COUNTER_U64_DEFINE_EARLY(swap_free_deferred); 188 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_deferred, 189 CTLFLAG_RD, &swap_free_deferred, 190 "Number of pages that deferred freeing swap space"); 191 192 static COUNTER_U64_DEFINE_EARLY(swap_free_completed); 193 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_completed, 194 CTLFLAG_RD, &swap_free_completed, 195 "Number of deferred frees completed"); 196 197 static int 198 sysctl_page_shift(SYSCTL_HANDLER_ARGS) 199 { 200 uint64_t newval; 201 u_long value = *(u_long *)arg1; 202 203 newval = ((uint64_t)value) << PAGE_SHIFT; 204 return (sysctl_handle_64(oidp, &newval, 0, req)); 205 } 206 207 static bool 208 swap_reserve_by_cred_rlimit(u_long pincr, struct ucred *cred, int oc) 209 { 210 struct uidinfo *uip; 211 u_long prev; 212 213 uip = cred->cr_ruidinfo; 214 215 prev = atomic_fetchadd_long(&uip->ui_vmsize, pincr); 216 if ((oc & SWAP_RESERVE_RLIMIT_ON) != 0 && 217 prev + pincr > lim_cur(curthread, RLIMIT_SWAP) && 218 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT) != 0) { 219 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pincr); 220 KASSERT(prev >= pincr, 221 ("negative vmsize for uid %d\n", uip->ui_uid)); 222 return (false); 223 } 224 return (true); 225 } 226 227 static void 228 swap_release_by_cred_rlimit(u_long pdecr, struct ucred *cred) 229 { 230 struct uidinfo *uip; 231 #ifdef INVARIANTS 232 u_long prev; 233 #endif 234 235 uip = cred->cr_ruidinfo; 236 237 #ifdef INVARIANTS 238 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pdecr); 239 KASSERT(prev >= pdecr, 240 ("negative vmsize for uid %d\n", uip->ui_uid)); 241 #else 242 atomic_subtract_long(&uip->ui_vmsize, pdecr); 243 #endif 244 } 245 246 static void 247 swap_reserve_force_rlimit(u_long pincr, struct ucred *cred) 248 { 249 struct uidinfo *uip; 250 251 uip = cred->cr_ruidinfo; 252 atomic_add_long(&uip->ui_vmsize, pincr); 253 } 254 255 bool 256 swap_reserve(vm_ooffset_t incr) 257 { 258 259 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 260 } 261 262 bool 263 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 264 { 265 u_long r, s, prev, pincr; 266 #ifdef RACCT 267 int error; 268 #endif 269 int oc; 270 static int curfail; 271 static struct timeval lastfail; 272 273 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", 274 __func__, (uintmax_t)incr)); 275 276 #ifdef RACCT 277 if (RACCT_ENABLED()) { 278 PROC_LOCK(curproc); 279 error = racct_add(curproc, RACCT_SWAP, incr); 280 PROC_UNLOCK(curproc); 281 if (error != 0) 282 return (false); 283 } 284 #endif 285 286 pincr = atop(incr); 287 prev = atomic_fetchadd_long(&swap_reserved, pincr); 288 r = prev + pincr; 289 s = swap_total; 290 oc = atomic_load_int(&vm_overcommit); 291 if (r > s && (oc & SWAP_RESERVE_ALLOW_NONWIRED) != 0) { 292 s += vm_cnt.v_page_count - vm_cnt.v_free_reserved - 293 vm_wire_count(); 294 } 295 if ((oc & SWAP_RESERVE_FORCE_ON) != 0 && r > s && 296 priv_check(curthread, PRIV_VM_SWAP_NOQUOTA) != 0) { 297 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 298 KASSERT(prev >= pincr, 299 ("swap_reserved < incr on overcommit fail")); 300 goto out_error; 301 } 302 303 if (!swap_reserve_by_cred_rlimit(pincr, cred, oc)) { 304 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 305 KASSERT(prev >= pincr, 306 ("swap_reserved < incr on overcommit fail")); 307 goto out_error; 308 } 309 310 return (true); 311 312 out_error: 313 if (ppsratecheck(&lastfail, &curfail, 1)) { 314 printf("uid %d, pid %d: swap reservation " 315 "for %jd bytes failed\n", 316 cred->cr_ruidinfo->ui_uid, curproc->p_pid, incr); 317 } 318 #ifdef RACCT 319 if (RACCT_ENABLED()) { 320 PROC_LOCK(curproc); 321 racct_sub(curproc, RACCT_SWAP, incr); 322 PROC_UNLOCK(curproc); 323 } 324 #endif 325 326 return (false); 327 } 328 329 void 330 swap_reserve_force(vm_ooffset_t incr) 331 { 332 u_long pincr; 333 334 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", 335 __func__, (uintmax_t)incr)); 336 337 #ifdef RACCT 338 if (RACCT_ENABLED()) { 339 PROC_LOCK(curproc); 340 racct_add_force(curproc, RACCT_SWAP, incr); 341 PROC_UNLOCK(curproc); 342 } 343 #endif 344 pincr = atop(incr); 345 atomic_add_long(&swap_reserved, pincr); 346 swap_reserve_force_rlimit(pincr, curthread->td_ucred); 347 } 348 349 void 350 swap_release(vm_ooffset_t decr) 351 { 352 struct ucred *cred; 353 354 PROC_LOCK(curproc); 355 cred = curproc->p_ucred; 356 swap_release_by_cred(decr, cred); 357 PROC_UNLOCK(curproc); 358 } 359 360 void 361 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 362 { 363 u_long pdecr; 364 #ifdef INVARIANTS 365 u_long prev; 366 #endif 367 368 KASSERT((decr & PAGE_MASK) == 0, ("%s: decr: %ju & PAGE_MASK", 369 __func__, (uintmax_t)decr)); 370 371 pdecr = atop(decr); 372 #ifdef INVARIANTS 373 prev = atomic_fetchadd_long(&swap_reserved, -pdecr); 374 KASSERT(prev >= pdecr, ("swap_reserved < decr")); 375 #else 376 atomic_subtract_long(&swap_reserved, pdecr); 377 #endif 378 379 swap_release_by_cred_rlimit(pdecr, cred); 380 #ifdef RACCT 381 if (racct_enable) 382 racct_sub_cred(cred, RACCT_SWAP, decr); 383 #endif 384 } 385 386 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 387 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 388 static struct mtx swbuf_mtx; /* to sync nsw_wcount_async */ 389 static int nsw_wcount_async; /* limit async write buffers */ 390 static int nsw_wcount_async_max;/* assigned maximum */ 391 int nsw_cluster_max; /* maximum VOP I/O allowed */ 392 393 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 394 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 395 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 396 "Maximum running async swap ops"); 397 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS); 398 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD | 399 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A", 400 "Swap Fragmentation Info"); 401 402 static struct sx sw_alloc_sx; 403 404 /* 405 * "named" and "unnamed" anon region objects. Try to reduce the overhead 406 * of searching a named list by hashing it just a little. 407 */ 408 409 #define NOBJLISTS 8 410 411 #define NOBJLIST(handle) \ 412 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 413 414 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 415 static uma_zone_t swwbuf_zone; 416 static uma_zone_t swrbuf_zone; 417 static uma_zone_t swblk_zone; 418 static uma_zone_t swpctrie_zone; 419 420 /* 421 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 422 * calls hooked from other parts of the VM system and do not appear here. 423 * (see vm/swap_pager.h). 424 */ 425 static vm_object_t 426 swap_pager_alloc(void *handle, vm_ooffset_t size, 427 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 428 static void swap_pager_dealloc(vm_object_t object); 429 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, 430 int *); 431 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, 432 int *, pgo_getpages_iodone_t, void *); 433 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, int, int *); 434 static boolean_t 435 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 436 static void swap_pager_init(void); 437 static void swap_pager_unswapped(vm_page_t); 438 static void swap_pager_swapoff(struct swdevt *sp); 439 static void swap_pager_update_writecount(vm_object_t object, 440 vm_offset_t start, vm_offset_t end); 441 static void swap_pager_release_writecount(vm_object_t object, 442 vm_offset_t start, vm_offset_t end); 443 static void swap_pager_freespace_pgo(vm_object_t object, vm_pindex_t start, 444 vm_size_t size); 445 446 const struct pagerops swappagerops = { 447 .pgo_kvme_type = KVME_TYPE_SWAP, 448 .pgo_init = swap_pager_init, /* early system initialization of pager */ 449 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 450 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 451 .pgo_getpages = swap_pager_getpages, /* pagein */ 452 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 453 .pgo_putpages = swap_pager_putpages, /* pageout */ 454 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 455 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 456 .pgo_update_writecount = swap_pager_update_writecount, 457 .pgo_release_writecount = swap_pager_release_writecount, 458 .pgo_freespace = swap_pager_freespace_pgo, 459 }; 460 461 /* 462 * swap_*() routines are externally accessible. swp_*() routines are 463 * internal. 464 */ 465 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 466 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 467 468 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 469 "Maximum size of a swap block in pages"); 470 471 static void swp_sizecheck(void); 472 static void swp_pager_async_iodone(struct buf *bp); 473 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit); 474 static void swp_pager_free_empty_swblk(vm_object_t, struct swblk *sb); 475 static int swapongeom(struct vnode *); 476 static int swaponvp(struct thread *, struct vnode *, u_long); 477 static int swapoff_one(struct swdevt *sp, struct ucred *cred, 478 u_int flags); 479 480 /* 481 * Swap bitmap functions 482 */ 483 static void swp_pager_freeswapspace(const struct page_range *range); 484 static daddr_t swp_pager_getswapspace(int *npages); 485 486 /* 487 * Metadata functions 488 */ 489 static daddr_t swp_pager_meta_build(struct pctrie_iter *, vm_object_t object, 490 vm_pindex_t, daddr_t, bool); 491 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t, 492 vm_size_t *); 493 static void swp_pager_meta_transfer(vm_object_t src, vm_object_t dst, 494 vm_pindex_t pindex, vm_pindex_t count); 495 static void swp_pager_meta_free_all(vm_object_t); 496 static daddr_t swp_pager_meta_lookup(vm_object_t, vm_pindex_t); 497 498 static void 499 swp_pager_init_freerange(struct page_range *range) 500 { 501 range->start = SWAPBLK_NONE; 502 range->num = 0; 503 } 504 505 static void 506 swp_pager_update_freerange(struct page_range *range, daddr_t addr) 507 { 508 if (range->start + range->num == addr) { 509 range->num++; 510 } else { 511 swp_pager_freeswapspace(range); 512 range->start = addr; 513 range->num = 1; 514 } 515 } 516 517 static void * 518 swblk_trie_alloc(struct pctrie *ptree) 519 { 520 521 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? 522 M_USE_RESERVE : 0))); 523 } 524 525 static void 526 swblk_trie_free(struct pctrie *ptree, void *node) 527 { 528 529 uma_zfree(swpctrie_zone, node); 530 } 531 532 static int 533 swblk_start(struct swblk *sb, vm_pindex_t pindex) 534 { 535 return (sb == NULL || sb->p >= pindex ? 536 0 : pindex % SWAP_META_PAGES); 537 } 538 539 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); 540 541 static struct swblk * 542 swblk_lookup(vm_object_t object, vm_pindex_t pindex) 543 { 544 return (SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 545 rounddown(pindex, SWAP_META_PAGES))); 546 } 547 548 static void 549 swblk_lookup_remove(vm_object_t object, struct swblk *sb) 550 { 551 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 552 } 553 554 static bool 555 swblk_is_empty(vm_object_t object) 556 { 557 return (pctrie_is_empty(&object->un_pager.swp.swp_blks)); 558 } 559 560 static void 561 swblk_iter_init_only(struct pctrie_iter *blks, vm_object_t object) 562 { 563 VM_OBJECT_ASSERT_LOCKED(object); 564 MPASS((object->flags & OBJ_SWAP) != 0); 565 pctrie_iter_init(blks, &object->un_pager.swp.swp_blks); 566 } 567 568 569 static struct swblk * 570 swblk_iter_init(struct pctrie_iter *blks, vm_object_t object, 571 vm_pindex_t pindex) 572 { 573 swblk_iter_init_only(blks, object); 574 return (SWAP_PCTRIE_ITER_LOOKUP_GE(blks, 575 rounddown(pindex, SWAP_META_PAGES))); 576 } 577 578 static struct swblk * 579 swblk_iter_reinit(struct pctrie_iter *blks, vm_object_t object, 580 vm_pindex_t pindex) 581 { 582 swblk_iter_init_only(blks, object); 583 return (SWAP_PCTRIE_ITER_LOOKUP(blks, 584 rounddown(pindex, SWAP_META_PAGES))); 585 } 586 587 static struct swblk * 588 swblk_iter_limit_init(struct pctrie_iter *blks, vm_object_t object, 589 vm_pindex_t pindex, vm_pindex_t limit) 590 { 591 VM_OBJECT_ASSERT_LOCKED(object); 592 MPASS((object->flags & OBJ_SWAP) != 0); 593 pctrie_iter_limit_init(blks, &object->un_pager.swp.swp_blks, limit); 594 return (SWAP_PCTRIE_ITER_LOOKUP_GE(blks, 595 rounddown(pindex, SWAP_META_PAGES))); 596 } 597 598 static struct swblk * 599 swblk_iter_next(struct pctrie_iter *blks) 600 { 601 return (SWAP_PCTRIE_ITER_JUMP_GE(blks, SWAP_META_PAGES)); 602 } 603 604 static struct swblk * 605 swblk_iter_lookup(struct pctrie_iter *blks, vm_pindex_t pindex) 606 { 607 return (SWAP_PCTRIE_ITER_LOOKUP(blks, 608 rounddown(pindex, SWAP_META_PAGES))); 609 } 610 611 static int 612 swblk_iter_insert(struct pctrie_iter *blks, struct swblk *sb) 613 { 614 return (SWAP_PCTRIE_ITER_INSERT(blks, sb)); 615 } 616 617 static void 618 swblk_iter_remove(struct pctrie_iter *blks) 619 { 620 SWAP_PCTRIE_ITER_REMOVE(blks); 621 } 622 623 /* 624 * SWP_SIZECHECK() - update swap_pager_full indication 625 * 626 * update the swap_pager_almost_full indication and warn when we are 627 * about to run out of swap space, using lowat/hiwat hysteresis. 628 * 629 * Clear swap_pager_full ( task killing ) indication when lowat is met. 630 * 631 * No restrictions on call 632 * This routine may not block. 633 */ 634 static void 635 swp_sizecheck(void) 636 { 637 638 if (swap_pager_avail < nswap_lowat) { 639 if (swap_pager_almost_full == 0) { 640 printf("swap_pager: out of swap space\n"); 641 swap_pager_almost_full = 1; 642 } 643 } else { 644 swap_pager_full = 0; 645 if (swap_pager_avail > nswap_hiwat) 646 swap_pager_almost_full = 0; 647 } 648 } 649 650 /* 651 * SWAP_PAGER_INIT() - initialize the swap pager! 652 * 653 * Expected to be started from system init. NOTE: This code is run 654 * before much else so be careful what you depend on. Most of the VM 655 * system has yet to be initialized at this point. 656 */ 657 static void 658 swap_pager_init(void) 659 { 660 /* 661 * Initialize object lists 662 */ 663 int i; 664 665 for (i = 0; i < NOBJLISTS; ++i) 666 TAILQ_INIT(&swap_pager_object_list[i]); 667 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 668 sx_init(&sw_alloc_sx, "swspsx"); 669 sx_init(&swdev_syscall_lock, "swsysc"); 670 671 /* 672 * The nsw_cluster_max is constrained by the bp->b_pages[] 673 * array, which has maxphys / PAGE_SIZE entries, and our locally 674 * defined MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 675 * constrained by the swap device interleave stripe size. 676 * 677 * Initialized early so that GEOM_ELI can see it. 678 */ 679 nsw_cluster_max = min(maxphys / PAGE_SIZE, MAX_PAGEOUT_CLUSTER); 680 } 681 682 /* 683 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 684 * 685 * Expected to be started from pageout process once, prior to entering 686 * its main loop. 687 */ 688 void 689 swap_pager_swap_init(void) 690 { 691 unsigned long n, n2; 692 693 /* 694 * Number of in-transit swap bp operations. Don't 695 * exhaust the pbufs completely. Make sure we 696 * initialize workable values (0 will work for hysteresis 697 * but it isn't very efficient). 698 * 699 * Currently we hardwire nsw_wcount_async to 4. This limit is 700 * designed to prevent other I/O from having high latencies due to 701 * our pageout I/O. The value 4 works well for one or two active swap 702 * devices but is probably a little low if you have more. Even so, 703 * a higher value would probably generate only a limited improvement 704 * with three or four active swap devices since the system does not 705 * typically have to pageout at extreme bandwidths. We will want 706 * at least 2 per swap devices, and 4 is a pretty good value if you 707 * have one NFS swap device due to the command/ack latency over NFS. 708 * So it all works out pretty well. 709 * 710 * nsw_cluster_max is initialized in swap_pager_init(). 711 */ 712 713 nsw_wcount_async = 4; 714 nsw_wcount_async_max = nsw_wcount_async; 715 mtx_init(&swbuf_mtx, "async swbuf mutex", NULL, MTX_DEF); 716 717 swwbuf_zone = pbuf_zsecond_create("swwbuf", nswbuf / 4); 718 swrbuf_zone = pbuf_zsecond_create("swrbuf", nswbuf / 2); 719 720 /* 721 * Initialize our zone, taking the user's requested size or 722 * estimating the number we need based on the number of pages 723 * in the system. 724 */ 725 n = maxswzone != 0 ? maxswzone / sizeof(struct swblk) : 726 vm_cnt.v_page_count / 2; 727 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, 728 pctrie_zone_init, NULL, UMA_ALIGN_PTR, 0); 729 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, 730 NULL, NULL, _Alignof(struct swblk) - 1, 0); 731 n2 = n; 732 do { 733 if (uma_zone_reserve_kva(swblk_zone, n)) 734 break; 735 /* 736 * if the allocation failed, try a zone two thirds the 737 * size of the previous attempt. 738 */ 739 n -= ((n + 2) / 3); 740 } while (n > 0); 741 742 /* 743 * Often uma_zone_reserve_kva() cannot reserve exactly the 744 * requested size. Account for the difference when 745 * calculating swap_maxpages. 746 */ 747 n = uma_zone_get_max(swblk_zone); 748 749 if (n < n2) 750 printf("Swap blk zone entries changed from %lu to %lu.\n", 751 n2, n); 752 /* absolute maximum we can handle assuming 100% efficiency */ 753 swap_maxpages = n * SWAP_META_PAGES; 754 swzone = n * sizeof(struct swblk); 755 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 756 printf("Cannot reserve swap pctrie zone, " 757 "reduce kern.maxswzone.\n"); 758 } 759 760 bool 761 swap_pager_init_object(vm_object_t object, void *handle, struct ucred *cred, 762 vm_ooffset_t size, vm_ooffset_t offset) 763 { 764 if (cred != NULL) { 765 if (!swap_reserve_by_cred(size, cred)) 766 return (false); 767 crhold(cred); 768 } 769 770 object->un_pager.swp.writemappings = 0; 771 object->handle = handle; 772 if (cred != NULL) { 773 object->cred = cred; 774 object->charge = size; 775 } 776 return (true); 777 } 778 779 static vm_object_t 780 swap_pager_alloc_init(objtype_t otype, void *handle, struct ucred *cred, 781 vm_ooffset_t size, vm_ooffset_t offset) 782 { 783 vm_object_t object; 784 785 /* 786 * The un_pager.swp.swp_blks trie is initialized by 787 * vm_object_allocate() to ensure the correct order of 788 * visibility to other threads. 789 */ 790 object = vm_object_allocate(otype, OFF_TO_IDX(offset + 791 PAGE_MASK + size)); 792 793 if (!swap_pager_init_object(object, handle, cred, size, offset)) { 794 vm_object_deallocate(object); 795 return (NULL); 796 } 797 return (object); 798 } 799 800 /* 801 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 802 * its metadata structures. 803 * 804 * This routine is called from the mmap and fork code to create a new 805 * OBJT_SWAP object. 806 * 807 * This routine must ensure that no live duplicate is created for 808 * the named object request, which is protected against by 809 * holding the sw_alloc_sx lock in case handle != NULL. 810 */ 811 static vm_object_t 812 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 813 vm_ooffset_t offset, struct ucred *cred) 814 { 815 vm_object_t object; 816 817 if (handle != NULL) { 818 /* 819 * Reference existing named region or allocate new one. There 820 * should not be a race here against swp_pager_meta_build() 821 * as called from vm_page_remove() in regards to the lookup 822 * of the handle. 823 */ 824 sx_xlock(&sw_alloc_sx); 825 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 826 if (object == NULL) { 827 object = swap_pager_alloc_init(OBJT_SWAP, handle, cred, 828 size, offset); 829 if (object != NULL) { 830 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 831 object, pager_object_list); 832 } 833 } 834 sx_xunlock(&sw_alloc_sx); 835 } else { 836 object = swap_pager_alloc_init(OBJT_SWAP, handle, cred, 837 size, offset); 838 } 839 return (object); 840 } 841 842 /* 843 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 844 * 845 * The swap backing for the object is destroyed. The code is 846 * designed such that we can reinstantiate it later, but this 847 * routine is typically called only when the entire object is 848 * about to be destroyed. 849 * 850 * The object must be locked. 851 */ 852 static void 853 swap_pager_dealloc(vm_object_t object) 854 { 855 856 VM_OBJECT_ASSERT_WLOCKED(object); 857 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 858 859 /* 860 * Remove from list right away so lookups will fail if we block for 861 * pageout completion. 862 */ 863 if ((object->flags & OBJ_ANON) == 0 && object->handle != NULL) { 864 VM_OBJECT_WUNLOCK(object); 865 sx_xlock(&sw_alloc_sx); 866 TAILQ_REMOVE(NOBJLIST(object->handle), object, 867 pager_object_list); 868 sx_xunlock(&sw_alloc_sx); 869 VM_OBJECT_WLOCK(object); 870 } 871 872 vm_object_pip_wait(object, "swpdea"); 873 874 /* 875 * Free all remaining metadata. We only bother to free it from 876 * the swap meta data. We do not attempt to free swapblk's still 877 * associated with vm_page_t's for this object. We do not care 878 * if paging is still in progress on some objects. 879 */ 880 swp_pager_meta_free_all(object); 881 object->handle = NULL; 882 object->type = OBJT_DEAD; 883 884 /* 885 * Release the allocation charge. 886 */ 887 if (object->cred != NULL) { 888 swap_release_by_cred(object->charge, object->cred); 889 object->charge = 0; 890 crfree(object->cred); 891 object->cred = NULL; 892 } 893 894 /* 895 * Hide the object from swap_pager_swapoff(). 896 */ 897 vm_object_clear_flag(object, OBJ_SWAP); 898 } 899 900 /************************************************************************ 901 * SWAP PAGER BITMAP ROUTINES * 902 ************************************************************************/ 903 904 /* 905 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 906 * 907 * Allocate swap for up to the requested number of pages. The 908 * starting swap block number (a page index) is returned or 909 * SWAPBLK_NONE if the allocation failed. 910 * 911 * Also has the side effect of advising that somebody made a mistake 912 * when they configured swap and didn't configure enough. 913 * 914 * This routine may not sleep. 915 * 916 * We allocate in round-robin fashion from the configured devices. 917 */ 918 static daddr_t 919 swp_pager_getswapspace(int *io_npages) 920 { 921 daddr_t blk; 922 struct swdevt *sp; 923 int mpages, npages; 924 925 KASSERT(*io_npages >= 1, 926 ("%s: npages not positive", __func__)); 927 blk = SWAPBLK_NONE; 928 mpages = *io_npages; 929 npages = imin(BLIST_MAX_ALLOC, mpages); 930 mtx_lock(&sw_dev_mtx); 931 sp = swdevhd; 932 while (!TAILQ_EMPTY(&swtailq)) { 933 if (sp == NULL) 934 sp = TAILQ_FIRST(&swtailq); 935 if ((sp->sw_flags & SW_CLOSING) == 0) 936 blk = blist_alloc(sp->sw_blist, &npages, mpages); 937 if (blk != SWAPBLK_NONE) 938 break; 939 sp = TAILQ_NEXT(sp, sw_list); 940 if (swdevhd == sp) { 941 if (npages == 1) 942 break; 943 mpages = npages - 1; 944 npages >>= 1; 945 } 946 } 947 if (blk != SWAPBLK_NONE) { 948 *io_npages = npages; 949 blk += sp->sw_first; 950 sp->sw_used += npages; 951 swap_pager_avail -= npages; 952 swp_sizecheck(); 953 swdevhd = TAILQ_NEXT(sp, sw_list); 954 } else { 955 if (swap_pager_full != 2) { 956 printf("swp_pager_getswapspace(%d): failed\n", 957 *io_npages); 958 swap_pager_full = 2; 959 swap_pager_almost_full = 1; 960 } 961 swdevhd = NULL; 962 } 963 mtx_unlock(&sw_dev_mtx); 964 return (blk); 965 } 966 967 static bool 968 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 969 { 970 971 return (blk >= sp->sw_first && blk < sp->sw_end); 972 } 973 974 static void 975 swp_pager_strategy(struct buf *bp) 976 { 977 struct swdevt *sp; 978 979 mtx_lock(&sw_dev_mtx); 980 TAILQ_FOREACH(sp, &swtailq, sw_list) { 981 if (swp_pager_isondev(bp->b_blkno, sp)) { 982 mtx_unlock(&sw_dev_mtx); 983 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 984 unmapped_buf_allowed) { 985 bp->b_data = unmapped_buf; 986 bp->b_offset = 0; 987 } else { 988 pmap_qenter((vm_offset_t)bp->b_data, 989 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 990 } 991 sp->sw_strategy(bp, sp); 992 return; 993 } 994 } 995 panic("Swapdev not found"); 996 } 997 998 /* 999 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 1000 * 1001 * This routine returns the specified swap blocks back to the bitmap. 1002 * 1003 * This routine may not sleep. 1004 */ 1005 static void 1006 swp_pager_freeswapspace(const struct page_range *range) 1007 { 1008 daddr_t blk, npages; 1009 struct swdevt *sp; 1010 1011 blk = range->start; 1012 npages = range->num; 1013 if (npages == 0) 1014 return; 1015 mtx_lock(&sw_dev_mtx); 1016 TAILQ_FOREACH(sp, &swtailq, sw_list) { 1017 if (swp_pager_isondev(blk, sp)) { 1018 sp->sw_used -= npages; 1019 /* 1020 * If we are attempting to stop swapping on 1021 * this device, we don't want to mark any 1022 * blocks free lest they be reused. 1023 */ 1024 if ((sp->sw_flags & SW_CLOSING) == 0) { 1025 blist_free(sp->sw_blist, blk - sp->sw_first, 1026 npages); 1027 swap_pager_avail += npages; 1028 swp_sizecheck(); 1029 } 1030 mtx_unlock(&sw_dev_mtx); 1031 return; 1032 } 1033 } 1034 panic("Swapdev not found"); 1035 } 1036 1037 /* 1038 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 1039 */ 1040 static int 1041 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 1042 { 1043 struct sbuf sbuf; 1044 struct swdevt *sp; 1045 const char *devname; 1046 int error; 1047 1048 error = sysctl_wire_old_buffer(req, 0); 1049 if (error != 0) 1050 return (error); 1051 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 1052 mtx_lock(&sw_dev_mtx); 1053 TAILQ_FOREACH(sp, &swtailq, sw_list) { 1054 if (vn_isdisk(sp->sw_vp)) 1055 devname = devtoname(sp->sw_vp->v_rdev); 1056 else 1057 devname = "[file]"; 1058 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 1059 blist_stats(sp->sw_blist, &sbuf); 1060 } 1061 mtx_unlock(&sw_dev_mtx); 1062 error = sbuf_finish(&sbuf); 1063 sbuf_delete(&sbuf); 1064 return (error); 1065 } 1066 1067 /* 1068 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 1069 * range within an object. 1070 * 1071 * This routine removes swapblk assignments from swap metadata. 1072 * 1073 * The external callers of this routine typically have already destroyed 1074 * or renamed vm_page_t's associated with this range in the object so 1075 * we should be ok. 1076 * 1077 * The object must be locked. 1078 */ 1079 void 1080 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size, 1081 vm_size_t *freed) 1082 { 1083 MPASS((object->flags & OBJ_SWAP) != 0); 1084 1085 swp_pager_meta_free(object, start, size, freed); 1086 } 1087 1088 static void 1089 swap_pager_freespace_pgo(vm_object_t object, vm_pindex_t start, vm_size_t size) 1090 { 1091 MPASS((object->flags & OBJ_SWAP) != 0); 1092 1093 swp_pager_meta_free(object, start, size, NULL); 1094 } 1095 1096 /* 1097 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 1098 * 1099 * Assigns swap blocks to the specified range within the object. The 1100 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 1101 * 1102 * Returns 0 on success, -1 on failure. 1103 */ 1104 int 1105 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_pindex_t size) 1106 { 1107 struct pctrie_iter blks; 1108 struct page_range range; 1109 daddr_t addr, blk; 1110 vm_pindex_t i, j; 1111 int n; 1112 1113 swp_pager_init_freerange(&range); 1114 VM_OBJECT_WLOCK(object); 1115 swblk_iter_init_only(&blks, object); 1116 for (i = 0; i < size; i += n) { 1117 n = MIN(size - i, INT_MAX); 1118 blk = swp_pager_getswapspace(&n); 1119 if (blk == SWAPBLK_NONE) { 1120 swp_pager_meta_free(object, start, i, NULL); 1121 VM_OBJECT_WUNLOCK(object); 1122 return (-1); 1123 } 1124 for (j = 0; j < n; ++j) { 1125 addr = swp_pager_meta_build(&blks, object, 1126 start + i + j, blk + j, false); 1127 if (addr != SWAPBLK_NONE) 1128 swp_pager_update_freerange(&range, addr); 1129 } 1130 } 1131 swp_pager_freeswapspace(&range); 1132 VM_OBJECT_WUNLOCK(object); 1133 return (0); 1134 } 1135 1136 /* 1137 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 1138 * and destroy the source. 1139 * 1140 * Copy any valid swapblks from the source to the destination. In 1141 * cases where both the source and destination have a valid swapblk, 1142 * we keep the destination's. 1143 * 1144 * This routine is allowed to sleep. It may sleep allocating metadata 1145 * indirectly through swp_pager_meta_build(). 1146 * 1147 * The source object contains no vm_page_t's (which is just as well) 1148 * 1149 * The source and destination objects must be locked. 1150 * Both object locks may temporarily be released. 1151 */ 1152 void 1153 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 1154 vm_pindex_t offset, int destroysource) 1155 { 1156 VM_OBJECT_ASSERT_WLOCKED(srcobject); 1157 VM_OBJECT_ASSERT_WLOCKED(dstobject); 1158 1159 /* 1160 * If destroysource is set, we remove the source object from the 1161 * swap_pager internal queue now. 1162 */ 1163 if (destroysource && (srcobject->flags & OBJ_ANON) == 0 && 1164 srcobject->handle != NULL) { 1165 VM_OBJECT_WUNLOCK(srcobject); 1166 VM_OBJECT_WUNLOCK(dstobject); 1167 sx_xlock(&sw_alloc_sx); 1168 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 1169 pager_object_list); 1170 sx_xunlock(&sw_alloc_sx); 1171 VM_OBJECT_WLOCK(dstobject); 1172 VM_OBJECT_WLOCK(srcobject); 1173 } 1174 1175 /* 1176 * Transfer source to destination. 1177 */ 1178 swp_pager_meta_transfer(srcobject, dstobject, offset, dstobject->size); 1179 1180 /* 1181 * Free left over swap blocks in source. 1182 */ 1183 if (destroysource) 1184 swp_pager_meta_free_all(srcobject); 1185 } 1186 1187 /* 1188 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1189 * the requested page. 1190 * 1191 * We determine whether good backing store exists for the requested 1192 * page and return TRUE if it does, FALSE if it doesn't. 1193 * 1194 * If TRUE, we also try to determine how much valid, contiguous backing 1195 * store exists before and after the requested page. 1196 */ 1197 static boolean_t 1198 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1199 int *after) 1200 { 1201 daddr_t blk, blk0; 1202 int i; 1203 1204 VM_OBJECT_ASSERT_LOCKED(object); 1205 KASSERT((object->flags & OBJ_SWAP) != 0, 1206 ("%s: object not swappable", __func__)); 1207 1208 /* 1209 * do we have good backing store at the requested index ? 1210 */ 1211 blk0 = swp_pager_meta_lookup(object, pindex); 1212 if (blk0 == SWAPBLK_NONE) { 1213 if (before) 1214 *before = 0; 1215 if (after) 1216 *after = 0; 1217 return (FALSE); 1218 } 1219 1220 /* 1221 * find backwards-looking contiguous good backing store 1222 */ 1223 if (before != NULL) { 1224 for (i = 1; i < SWB_NPAGES; i++) { 1225 if (i > pindex) 1226 break; 1227 blk = swp_pager_meta_lookup(object, pindex - i); 1228 if (blk != blk0 - i) 1229 break; 1230 } 1231 *before = i - 1; 1232 } 1233 1234 /* 1235 * find forward-looking contiguous good backing store 1236 */ 1237 if (after != NULL) { 1238 for (i = 1; i < SWB_NPAGES; i++) { 1239 blk = swp_pager_meta_lookup(object, pindex + i); 1240 if (blk != blk0 + i) 1241 break; 1242 } 1243 *after = i - 1; 1244 } 1245 return (TRUE); 1246 } 1247 1248 static void 1249 swap_pager_unswapped_acct(vm_page_t m) 1250 { 1251 KASSERT((m->object->flags & OBJ_SWAP) != 0, 1252 ("Free object not swappable")); 1253 if ((m->a.flags & PGA_SWAP_FREE) != 0) 1254 counter_u64_add(swap_free_completed, 1); 1255 vm_page_aflag_clear(m, PGA_SWAP_FREE | PGA_SWAP_SPACE); 1256 1257 /* 1258 * The meta data only exists if the object is OBJT_SWAP 1259 * and even then might not be allocated yet. 1260 */ 1261 } 1262 1263 /* 1264 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1265 * 1266 * This removes any associated swap backing store, whether valid or 1267 * not, from the page. 1268 * 1269 * This routine is typically called when a page is made dirty, at 1270 * which point any associated swap can be freed. MADV_FREE also 1271 * calls us in a special-case situation 1272 * 1273 * NOTE!!! If the page is clean and the swap was valid, the caller 1274 * should make the page dirty before calling this routine. This routine 1275 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1276 * depends on it. 1277 * 1278 * This routine may not sleep. 1279 * 1280 * The object containing the page may be locked. 1281 */ 1282 static void 1283 swap_pager_unswapped(vm_page_t m) 1284 { 1285 struct page_range range; 1286 struct swblk *sb; 1287 vm_object_t obj; 1288 1289 /* 1290 * Handle enqueing deferred frees first. If we do not have the 1291 * object lock we wait for the page daemon to clear the space. 1292 */ 1293 obj = m->object; 1294 if (!VM_OBJECT_WOWNED(obj)) { 1295 VM_PAGE_OBJECT_BUSY_ASSERT(m); 1296 /* 1297 * The caller is responsible for synchronization but we 1298 * will harmlessly handle races. This is typically provided 1299 * by only calling unswapped() when a page transitions from 1300 * clean to dirty. 1301 */ 1302 if ((m->a.flags & (PGA_SWAP_SPACE | PGA_SWAP_FREE)) == 1303 PGA_SWAP_SPACE) { 1304 vm_page_aflag_set(m, PGA_SWAP_FREE); 1305 counter_u64_add(swap_free_deferred, 1); 1306 } 1307 return; 1308 } 1309 swap_pager_unswapped_acct(m); 1310 1311 sb = swblk_lookup(m->object, m->pindex); 1312 if (sb == NULL) 1313 return; 1314 range.start = sb->d[m->pindex % SWAP_META_PAGES]; 1315 if (range.start == SWAPBLK_NONE) 1316 return; 1317 range.num = 1; 1318 swp_pager_freeswapspace(&range); 1319 sb->d[m->pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 1320 swp_pager_free_empty_swblk(m->object, sb); 1321 } 1322 1323 /* 1324 * swap_pager_getpages() - bring pages in from swap 1325 * 1326 * Attempt to page in the pages in array "ma" of length "count". The 1327 * caller may optionally specify that additional pages preceding and 1328 * succeeding the specified range be paged in. The number of such pages 1329 * is returned in the "rbehind" and "rahead" parameters, and they will 1330 * be in the inactive queue upon return. 1331 * 1332 * The pages in "ma" must be busied and will remain busied upon return. 1333 */ 1334 static int 1335 swap_pager_getpages_locked(vm_object_t object, vm_page_t *ma, int count, 1336 int *rbehind, int *rahead) 1337 { 1338 struct buf *bp; 1339 vm_page_t bm, mpred, msucc, p; 1340 vm_pindex_t pindex; 1341 daddr_t blk; 1342 int i, maxahead, maxbehind, reqcount; 1343 1344 VM_OBJECT_ASSERT_WLOCKED(object); 1345 reqcount = count; 1346 1347 KASSERT((object->flags & OBJ_SWAP) != 0, 1348 ("%s: object not swappable", __func__)); 1349 if (!swap_pager_haspage(object, ma[0]->pindex, &maxbehind, &maxahead)) { 1350 VM_OBJECT_WUNLOCK(object); 1351 return (VM_PAGER_FAIL); 1352 } 1353 1354 KASSERT(reqcount - 1 <= maxahead, 1355 ("page count %d extends beyond swap block", reqcount)); 1356 1357 /* 1358 * Do not transfer any pages other than those that are xbusied 1359 * when running during a split or collapse operation. This 1360 * prevents clustering from re-creating pages which are being 1361 * moved into another object. 1362 */ 1363 if ((object->flags & (OBJ_SPLIT | OBJ_DEAD)) != 0) { 1364 maxahead = reqcount - 1; 1365 maxbehind = 0; 1366 } 1367 1368 /* 1369 * Clip the readahead and readbehind ranges to exclude resident pages. 1370 */ 1371 if (rahead != NULL) { 1372 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1373 pindex = ma[reqcount - 1]->pindex; 1374 msucc = TAILQ_NEXT(ma[reqcount - 1], listq); 1375 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1376 *rahead = msucc->pindex - pindex - 1; 1377 } 1378 if (rbehind != NULL) { 1379 *rbehind = imin(*rbehind, maxbehind); 1380 pindex = ma[0]->pindex; 1381 mpred = TAILQ_PREV(ma[0], pglist, listq); 1382 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1383 *rbehind = pindex - mpred->pindex - 1; 1384 } 1385 1386 bm = ma[0]; 1387 for (i = 0; i < count; i++) 1388 ma[i]->oflags |= VPO_SWAPINPROG; 1389 1390 /* 1391 * Allocate readahead and readbehind pages. 1392 */ 1393 if (rbehind != NULL) { 1394 for (i = 1; i <= *rbehind; i++) { 1395 p = vm_page_alloc(object, ma[0]->pindex - i, 1396 VM_ALLOC_NORMAL); 1397 if (p == NULL) 1398 break; 1399 p->oflags |= VPO_SWAPINPROG; 1400 bm = p; 1401 } 1402 *rbehind = i - 1; 1403 } 1404 if (rahead != NULL) { 1405 for (i = 0; i < *rahead; i++) { 1406 p = vm_page_alloc(object, 1407 ma[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1408 if (p == NULL) 1409 break; 1410 p->oflags |= VPO_SWAPINPROG; 1411 } 1412 *rahead = i; 1413 } 1414 if (rbehind != NULL) 1415 count += *rbehind; 1416 if (rahead != NULL) 1417 count += *rahead; 1418 1419 vm_object_pip_add(object, count); 1420 1421 pindex = bm->pindex; 1422 blk = swp_pager_meta_lookup(object, pindex); 1423 KASSERT(blk != SWAPBLK_NONE, 1424 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1425 1426 VM_OBJECT_WUNLOCK(object); 1427 bp = uma_zalloc(swrbuf_zone, M_WAITOK); 1428 MPASS((bp->b_flags & B_MAXPHYS) != 0); 1429 /* Pages cannot leave the object while busy. */ 1430 for (i = 0, p = bm; i < count; i++, p = TAILQ_NEXT(p, listq)) { 1431 MPASS(p->pindex == bm->pindex + i); 1432 bp->b_pages[i] = p; 1433 } 1434 1435 bp->b_flags |= B_PAGING; 1436 bp->b_iocmd = BIO_READ; 1437 bp->b_iodone = swp_pager_async_iodone; 1438 bp->b_rcred = crhold(thread0.td_ucred); 1439 bp->b_wcred = crhold(thread0.td_ucred); 1440 bp->b_blkno = blk; 1441 bp->b_bcount = PAGE_SIZE * count; 1442 bp->b_bufsize = PAGE_SIZE * count; 1443 bp->b_npages = count; 1444 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1445 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1446 1447 VM_CNT_INC(v_swapin); 1448 VM_CNT_ADD(v_swappgsin, count); 1449 1450 /* 1451 * perform the I/O. NOTE!!! bp cannot be considered valid after 1452 * this point because we automatically release it on completion. 1453 * Instead, we look at the one page we are interested in which we 1454 * still hold a lock on even through the I/O completion. 1455 * 1456 * The other pages in our ma[] array are also released on completion, 1457 * so we cannot assume they are valid anymore either. 1458 * 1459 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1460 */ 1461 BUF_KERNPROC(bp); 1462 swp_pager_strategy(bp); 1463 1464 /* 1465 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1466 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1467 * is set in the metadata for each page in the request. 1468 */ 1469 VM_OBJECT_WLOCK(object); 1470 /* This could be implemented more efficiently with aflags */ 1471 while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) { 1472 ma[0]->oflags |= VPO_SWAPSLEEP; 1473 VM_CNT_INC(v_intrans); 1474 if (VM_OBJECT_SLEEP(object, &object->handle, PSWP, 1475 "swread", hz * 20)) { 1476 printf( 1477 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1478 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1479 } 1480 } 1481 VM_OBJECT_WUNLOCK(object); 1482 1483 /* 1484 * If we had an unrecoverable read error pages will not be valid. 1485 */ 1486 for (i = 0; i < reqcount; i++) 1487 if (ma[i]->valid != VM_PAGE_BITS_ALL) 1488 return (VM_PAGER_ERROR); 1489 1490 return (VM_PAGER_OK); 1491 1492 /* 1493 * A final note: in a low swap situation, we cannot deallocate swap 1494 * and mark a page dirty here because the caller is likely to mark 1495 * the page clean when we return, causing the page to possibly revert 1496 * to all-zero's later. 1497 */ 1498 } 1499 1500 static int 1501 swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count, 1502 int *rbehind, int *rahead) 1503 { 1504 1505 VM_OBJECT_WLOCK(object); 1506 return (swap_pager_getpages_locked(object, ma, count, rbehind, rahead)); 1507 } 1508 1509 /* 1510 * swap_pager_getpages_async(): 1511 * 1512 * Right now this is emulation of asynchronous operation on top of 1513 * swap_pager_getpages(). 1514 */ 1515 static int 1516 swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count, 1517 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1518 { 1519 int r, error; 1520 1521 r = swap_pager_getpages(object, ma, count, rbehind, rahead); 1522 switch (r) { 1523 case VM_PAGER_OK: 1524 error = 0; 1525 break; 1526 case VM_PAGER_ERROR: 1527 error = EIO; 1528 break; 1529 case VM_PAGER_FAIL: 1530 error = EINVAL; 1531 break; 1532 default: 1533 panic("unhandled swap_pager_getpages() error %d", r); 1534 } 1535 (iodone)(arg, ma, count, error); 1536 1537 return (r); 1538 } 1539 1540 /* 1541 * swap_pager_putpages: 1542 * 1543 * Assign swap (if necessary) and initiate I/O on the specified pages. 1544 * 1545 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1546 * vm_page reservation system coupled with properly written VFS devices 1547 * should ensure that no low-memory deadlock occurs. This is an area 1548 * which needs work. 1549 * 1550 * The parent has N vm_object_pip_add() references prior to 1551 * calling us and will remove references for rtvals[] that are 1552 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1553 * completion. 1554 * 1555 * The parent has soft-busy'd the pages it passes us and will unbusy 1556 * those whose rtvals[] entry is not set to VM_PAGER_PEND on return. 1557 * We need to unbusy the rest on I/O completion. 1558 */ 1559 static void 1560 swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count, 1561 int flags, int *rtvals) 1562 { 1563 struct pctrie_iter blks; 1564 struct page_range range; 1565 struct buf *bp; 1566 daddr_t addr, blk; 1567 vm_page_t mreq; 1568 int i, j, n; 1569 bool async; 1570 1571 KASSERT(count == 0 || ma[0]->object == object, 1572 ("%s: object mismatch %p/%p", 1573 __func__, object, ma[0]->object)); 1574 1575 VM_OBJECT_WUNLOCK(object); 1576 async = curproc == pageproc && (flags & VM_PAGER_PUT_SYNC) == 0; 1577 swp_pager_init_freerange(&range); 1578 1579 /* 1580 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1581 * The page is left dirty until the pageout operation completes 1582 * successfully. 1583 */ 1584 for (i = 0; i < count; i += n) { 1585 /* Maximum I/O size is limited by maximum swap block size. */ 1586 n = min(count - i, nsw_cluster_max); 1587 1588 if (async) { 1589 mtx_lock(&swbuf_mtx); 1590 while (nsw_wcount_async == 0) 1591 msleep(&nsw_wcount_async, &swbuf_mtx, PVM, 1592 "swbufa", 0); 1593 nsw_wcount_async--; 1594 mtx_unlock(&swbuf_mtx); 1595 } 1596 1597 /* Get a block of swap of size up to size n. */ 1598 blk = swp_pager_getswapspace(&n); 1599 if (blk == SWAPBLK_NONE) { 1600 mtx_lock(&swbuf_mtx); 1601 if (++nsw_wcount_async == 1) 1602 wakeup(&nsw_wcount_async); 1603 mtx_unlock(&swbuf_mtx); 1604 for (j = 0; j < n; ++j) 1605 rtvals[i + j] = VM_PAGER_FAIL; 1606 continue; 1607 } 1608 VM_OBJECT_WLOCK(object); 1609 swblk_iter_init_only(&blks, object); 1610 for (j = 0; j < n; ++j) { 1611 mreq = ma[i + j]; 1612 vm_page_aflag_clear(mreq, PGA_SWAP_FREE); 1613 KASSERT(mreq->object == object, 1614 ("%s: object mismatch %p/%p", 1615 __func__, mreq->object, object)); 1616 addr = swp_pager_meta_build(&blks, object, 1617 mreq->pindex, blk + j, false); 1618 if (addr != SWAPBLK_NONE) 1619 swp_pager_update_freerange(&range, addr); 1620 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1621 mreq->oflags |= VPO_SWAPINPROG; 1622 } 1623 VM_OBJECT_WUNLOCK(object); 1624 1625 bp = uma_zalloc(swwbuf_zone, M_WAITOK); 1626 MPASS((bp->b_flags & B_MAXPHYS) != 0); 1627 if (async) 1628 bp->b_flags |= B_ASYNC; 1629 bp->b_flags |= B_PAGING; 1630 bp->b_iocmd = BIO_WRITE; 1631 1632 bp->b_rcred = crhold(thread0.td_ucred); 1633 bp->b_wcred = crhold(thread0.td_ucred); 1634 bp->b_bcount = PAGE_SIZE * n; 1635 bp->b_bufsize = PAGE_SIZE * n; 1636 bp->b_blkno = blk; 1637 for (j = 0; j < n; j++) 1638 bp->b_pages[j] = ma[i + j]; 1639 bp->b_npages = n; 1640 1641 /* 1642 * Must set dirty range for NFS to work. 1643 */ 1644 bp->b_dirtyoff = 0; 1645 bp->b_dirtyend = bp->b_bcount; 1646 1647 VM_CNT_INC(v_swapout); 1648 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1649 1650 /* 1651 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1652 * can call the async completion routine at the end of a 1653 * synchronous I/O operation. Otherwise, our caller would 1654 * perform duplicate unbusy and wakeup operations on the page 1655 * and object, respectively. 1656 */ 1657 for (j = 0; j < n; j++) 1658 rtvals[i + j] = VM_PAGER_PEND; 1659 1660 /* 1661 * asynchronous 1662 * 1663 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1664 */ 1665 if (async) { 1666 bp->b_iodone = swp_pager_async_iodone; 1667 BUF_KERNPROC(bp); 1668 swp_pager_strategy(bp); 1669 continue; 1670 } 1671 1672 /* 1673 * synchronous 1674 * 1675 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1676 */ 1677 bp->b_iodone = bdone; 1678 swp_pager_strategy(bp); 1679 1680 /* 1681 * Wait for the sync I/O to complete. 1682 */ 1683 bwait(bp, PVM, "swwrt"); 1684 1685 /* 1686 * Now that we are through with the bp, we can call the 1687 * normal async completion, which frees everything up. 1688 */ 1689 swp_pager_async_iodone(bp); 1690 } 1691 swp_pager_freeswapspace(&range); 1692 VM_OBJECT_WLOCK(object); 1693 } 1694 1695 /* 1696 * swp_pager_async_iodone: 1697 * 1698 * Completion routine for asynchronous reads and writes from/to swap. 1699 * Also called manually by synchronous code to finish up a bp. 1700 * 1701 * This routine may not sleep. 1702 */ 1703 static void 1704 swp_pager_async_iodone(struct buf *bp) 1705 { 1706 int i; 1707 vm_object_t object = NULL; 1708 1709 /* 1710 * Report error - unless we ran out of memory, in which case 1711 * we've already logged it in swapgeom_strategy(). 1712 */ 1713 if (bp->b_ioflags & BIO_ERROR && bp->b_error != ENOMEM) { 1714 printf( 1715 "swap_pager: I/O error - %s failed; blkno %ld," 1716 "size %ld, error %d\n", 1717 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1718 (long)bp->b_blkno, 1719 (long)bp->b_bcount, 1720 bp->b_error 1721 ); 1722 } 1723 1724 /* 1725 * remove the mapping for kernel virtual 1726 */ 1727 if (buf_mapped(bp)) 1728 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1729 else 1730 bp->b_data = bp->b_kvabase; 1731 1732 if (bp->b_npages) { 1733 object = bp->b_pages[0]->object; 1734 VM_OBJECT_WLOCK(object); 1735 } 1736 1737 /* 1738 * cleanup pages. If an error occurs writing to swap, we are in 1739 * very serious trouble. If it happens to be a disk error, though, 1740 * we may be able to recover by reassigning the swap later on. So 1741 * in this case we remove the m->swapblk assignment for the page 1742 * but do not free it in the rlist. The errornous block(s) are thus 1743 * never reallocated as swap. Redirty the page and continue. 1744 */ 1745 for (i = 0; i < bp->b_npages; ++i) { 1746 vm_page_t m = bp->b_pages[i]; 1747 1748 m->oflags &= ~VPO_SWAPINPROG; 1749 if (m->oflags & VPO_SWAPSLEEP) { 1750 m->oflags &= ~VPO_SWAPSLEEP; 1751 wakeup(&object->handle); 1752 } 1753 1754 /* We always have space after I/O, successful or not. */ 1755 vm_page_aflag_set(m, PGA_SWAP_SPACE); 1756 1757 if (bp->b_ioflags & BIO_ERROR) { 1758 /* 1759 * If an error occurs I'd love to throw the swapblk 1760 * away without freeing it back to swapspace, so it 1761 * can never be used again. But I can't from an 1762 * interrupt. 1763 */ 1764 if (bp->b_iocmd == BIO_READ) { 1765 /* 1766 * NOTE: for reads, m->dirty will probably 1767 * be overridden by the original caller of 1768 * getpages so don't play cute tricks here. 1769 */ 1770 vm_page_invalid(m); 1771 if (i < bp->b_pgbefore || 1772 i >= bp->b_npages - bp->b_pgafter) 1773 vm_page_free_invalid(m); 1774 } else { 1775 /* 1776 * If a write error occurs, reactivate page 1777 * so it doesn't clog the inactive list, 1778 * then finish the I/O. 1779 */ 1780 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1781 1782 /* PQ_UNSWAPPABLE? */ 1783 vm_page_activate(m); 1784 vm_page_sunbusy(m); 1785 } 1786 } else if (bp->b_iocmd == BIO_READ) { 1787 /* 1788 * NOTE: for reads, m->dirty will probably be 1789 * overridden by the original caller of getpages so 1790 * we cannot set them in order to free the underlying 1791 * swap in a low-swap situation. I don't think we'd 1792 * want to do that anyway, but it was an optimization 1793 * that existed in the old swapper for a time before 1794 * it got ripped out due to precisely this problem. 1795 */ 1796 KASSERT(!pmap_page_is_mapped(m), 1797 ("swp_pager_async_iodone: page %p is mapped", m)); 1798 KASSERT(m->dirty == 0, 1799 ("swp_pager_async_iodone: page %p is dirty", m)); 1800 1801 vm_page_valid(m); 1802 if (i < bp->b_pgbefore || 1803 i >= bp->b_npages - bp->b_pgafter) 1804 vm_page_readahead_finish(m); 1805 } else { 1806 /* 1807 * For write success, clear the dirty 1808 * status, then finish the I/O ( which decrements the 1809 * busy count and possibly wakes waiter's up ). 1810 * A page is only written to swap after a period of 1811 * inactivity. Therefore, we do not expect it to be 1812 * reused. 1813 */ 1814 KASSERT(!pmap_page_is_write_mapped(m), 1815 ("swp_pager_async_iodone: page %p is not write" 1816 " protected", m)); 1817 vm_page_undirty(m); 1818 vm_page_deactivate_noreuse(m); 1819 vm_page_sunbusy(m); 1820 } 1821 } 1822 1823 /* 1824 * adjust pip. NOTE: the original parent may still have its own 1825 * pip refs on the object. 1826 */ 1827 if (object != NULL) { 1828 vm_object_pip_wakeupn(object, bp->b_npages); 1829 VM_OBJECT_WUNLOCK(object); 1830 } 1831 1832 /* 1833 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1834 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1835 * trigger a KASSERT in relpbuf(). 1836 */ 1837 if (bp->b_vp) { 1838 bp->b_vp = NULL; 1839 bp->b_bufobj = NULL; 1840 } 1841 /* 1842 * release the physical I/O buffer 1843 */ 1844 if (bp->b_flags & B_ASYNC) { 1845 mtx_lock(&swbuf_mtx); 1846 if (++nsw_wcount_async == 1) 1847 wakeup(&nsw_wcount_async); 1848 mtx_unlock(&swbuf_mtx); 1849 } 1850 uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp); 1851 } 1852 1853 int 1854 swap_pager_nswapdev(void) 1855 { 1856 1857 return (nswapdev); 1858 } 1859 1860 static void 1861 swp_pager_force_dirty(struct page_range *range, vm_page_t m, daddr_t *blk) 1862 { 1863 vm_page_dirty(m); 1864 swap_pager_unswapped_acct(m); 1865 swp_pager_update_freerange(range, *blk); 1866 *blk = SWAPBLK_NONE; 1867 vm_page_launder(m); 1868 } 1869 1870 u_long 1871 swap_pager_swapped_pages(vm_object_t object) 1872 { 1873 struct pctrie_iter blks; 1874 struct swblk *sb; 1875 u_long res; 1876 int i; 1877 1878 VM_OBJECT_ASSERT_LOCKED(object); 1879 1880 if (swblk_is_empty(object)) 1881 return (0); 1882 1883 res = 0; 1884 for (sb = swblk_iter_init(&blks, object, 0); sb != NULL; 1885 sb = swblk_iter_next(&blks)) { 1886 for (i = 0; i < SWAP_META_PAGES; i++) { 1887 if (sb->d[i] != SWAPBLK_NONE) 1888 res++; 1889 } 1890 } 1891 return (res); 1892 } 1893 1894 /* 1895 * swap_pager_swapoff_object: 1896 * 1897 * Page in all of the pages that have been paged out for an object 1898 * to a swap device. 1899 */ 1900 static void 1901 swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object) 1902 { 1903 struct pctrie_iter blks, pages; 1904 struct page_range range; 1905 struct swblk *sb; 1906 vm_page_t m; 1907 int i, rahead, rv; 1908 bool sb_empty; 1909 1910 VM_OBJECT_ASSERT_WLOCKED(object); 1911 KASSERT((object->flags & OBJ_SWAP) != 0, 1912 ("%s: Object not swappable", __func__)); 1913 KASSERT((object->flags & OBJ_DEAD) == 0, 1914 ("%s: Object already dead", __func__)); 1915 KASSERT((sp->sw_flags & SW_CLOSING) != 0, 1916 ("%s: Device not blocking further allocations", __func__)); 1917 1918 vm_page_iter_init(&pages, object); 1919 swp_pager_init_freerange(&range); 1920 sb = swblk_iter_init(&blks, object, 0); 1921 while (sb != NULL) { 1922 sb_empty = true; 1923 for (i = 0; i < SWAP_META_PAGES; i++) { 1924 /* Skip an invalid block. */ 1925 if (sb->d[i] == SWAPBLK_NONE) 1926 continue; 1927 /* Skip a block not of this device. */ 1928 if (!swp_pager_isondev(sb->d[i], sp)) { 1929 sb_empty = false; 1930 continue; 1931 } 1932 1933 /* 1934 * Look for a page corresponding to this block. If the 1935 * found page has pending operations, sleep and restart 1936 * the scan. 1937 */ 1938 m = vm_page_iter_lookup(&pages, blks.index + i); 1939 if (m != NULL && (m->oflags & VPO_SWAPINPROG) != 0) { 1940 m->oflags |= VPO_SWAPSLEEP; 1941 VM_OBJECT_SLEEP(object, &object->handle, PSWP, 1942 "swpoff", 0); 1943 break; 1944 } 1945 1946 /* 1947 * If the found page is valid, mark it dirty and free 1948 * the swap block. 1949 */ 1950 if (m != NULL && vm_page_all_valid(m)) { 1951 swp_pager_force_dirty(&range, m, &sb->d[i]); 1952 continue; 1953 } 1954 /* Is there a page we can acquire or allocate? */ 1955 if (m != NULL) { 1956 if (!vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL)) 1957 break; 1958 } else if ((m = vm_page_alloc(object, blks.index + i, 1959 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL)) == NULL) 1960 break; 1961 1962 /* Get the page from swap, and restart the scan. */ 1963 vm_object_pip_add(object, 1); 1964 rahead = SWAP_META_PAGES; 1965 rv = swap_pager_getpages_locked(object, &m, 1, 1966 NULL, &rahead); 1967 if (rv != VM_PAGER_OK) 1968 panic("%s: read from swap failed: %d", 1969 __func__, rv); 1970 VM_OBJECT_WLOCK(object); 1971 vm_object_pip_wakeupn(object, 1); 1972 KASSERT(vm_page_all_valid(m), 1973 ("%s: Page %p not all valid", __func__, m)); 1974 vm_page_xunbusy(m); 1975 break; 1976 } 1977 if (i < SWAP_META_PAGES) { 1978 /* 1979 * The object lock has been released and regained. 1980 * Perhaps the object is now dead. 1981 */ 1982 if ((object->flags & OBJ_DEAD) != 0) { 1983 /* 1984 * Make sure that pending writes finish before 1985 * returning. 1986 */ 1987 vm_object_pip_wait(object, "swpoff"); 1988 swp_pager_meta_free_all(object); 1989 break; 1990 } 1991 1992 /* 1993 * The swapblk could have been freed, so reset the pages 1994 * iterator and search again for the first swblk at or 1995 * after blks.index. 1996 */ 1997 pctrie_iter_reset(&pages); 1998 sb = swblk_iter_init(&blks, object, blks.index); 1999 continue; 2000 } 2001 if (sb_empty) { 2002 swblk_iter_remove(&blks); 2003 uma_zfree(swblk_zone, sb); 2004 } 2005 2006 /* 2007 * It is safe to advance to the next block. No allocations 2008 * before blk.index have happened, even with the lock released, 2009 * because allocations on this device are blocked. 2010 */ 2011 sb = swblk_iter_next(&blks); 2012 } 2013 swp_pager_freeswapspace(&range); 2014 } 2015 2016 /* 2017 * swap_pager_swapoff: 2018 * 2019 * Page in all of the pages that have been paged out to the 2020 * given device. The corresponding blocks in the bitmap must be 2021 * marked as allocated and the device must be flagged SW_CLOSING. 2022 * There may be no processes swapped out to the device. 2023 * 2024 * This routine may block. 2025 */ 2026 static void 2027 swap_pager_swapoff(struct swdevt *sp) 2028 { 2029 vm_object_t object; 2030 int retries; 2031 2032 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2033 2034 retries = 0; 2035 full_rescan: 2036 mtx_lock(&vm_object_list_mtx); 2037 TAILQ_FOREACH(object, &vm_object_list, object_list) { 2038 if ((object->flags & OBJ_SWAP) == 0) 2039 continue; 2040 mtx_unlock(&vm_object_list_mtx); 2041 /* Depends on type-stability. */ 2042 VM_OBJECT_WLOCK(object); 2043 2044 /* 2045 * Dead objects are eventually terminated on their own. 2046 */ 2047 if ((object->flags & OBJ_DEAD) != 0) 2048 goto next_obj; 2049 2050 /* 2051 * Sync with fences placed after pctrie 2052 * initialization. We must not access pctrie below 2053 * unless we checked that our object is swap and not 2054 * dead. 2055 */ 2056 atomic_thread_fence_acq(); 2057 if ((object->flags & OBJ_SWAP) == 0) 2058 goto next_obj; 2059 2060 swap_pager_swapoff_object(sp, object); 2061 next_obj: 2062 VM_OBJECT_WUNLOCK(object); 2063 mtx_lock(&vm_object_list_mtx); 2064 } 2065 mtx_unlock(&vm_object_list_mtx); 2066 2067 if (sp->sw_used) { 2068 /* 2069 * Objects may be locked or paging to the device being 2070 * removed, so we will miss their pages and need to 2071 * make another pass. We have marked this device as 2072 * SW_CLOSING, so the activity should finish soon. 2073 */ 2074 retries++; 2075 if (retries > 100) { 2076 panic("swapoff: failed to locate %d swap blocks", 2077 sp->sw_used); 2078 } 2079 pause("swpoff", hz / 20); 2080 goto full_rescan; 2081 } 2082 EVENTHANDLER_INVOKE(swapoff, sp); 2083 } 2084 2085 /************************************************************************ 2086 * SWAP META DATA * 2087 ************************************************************************ 2088 * 2089 * These routines manipulate the swap metadata stored in the 2090 * OBJT_SWAP object. 2091 * 2092 * Swap metadata is implemented with a global hash and not directly 2093 * linked into the object. Instead the object simply contains 2094 * appropriate tracking counters. 2095 */ 2096 2097 /* 2098 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? 2099 */ 2100 static bool 2101 swp_pager_swblk_empty(struct swblk *sb, int start, int limit) 2102 { 2103 int i; 2104 2105 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); 2106 for (i = start; i < limit; i++) { 2107 if (sb->d[i] != SWAPBLK_NONE) 2108 return (false); 2109 } 2110 return (true); 2111 } 2112 2113 /* 2114 * SWP_PAGER_FREE_EMPTY_SWBLK() - frees if a block is free 2115 * 2116 * Nothing is done if the block is still in use. 2117 */ 2118 static void 2119 swp_pager_free_empty_swblk(vm_object_t object, struct swblk *sb) 2120 { 2121 2122 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 2123 swblk_lookup_remove(object, sb); 2124 uma_zfree(swblk_zone, sb); 2125 } 2126 } 2127 2128 /* 2129 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 2130 * 2131 * Try to add the specified swapblk to the object's swap metadata. If 2132 * nowait_noreplace is set, add the specified swapblk only if there is no 2133 * previously assigned swapblk at pindex. If the swapblk is invalid, and 2134 * replaces a valid swapblk, empty swap metadata is freed. If memory 2135 * allocation fails, and nowait_noreplace is set, return the specified 2136 * swapblk immediately to indicate failure; otherwise, wait and retry until 2137 * memory allocation succeeds. Return the previously assigned swapblk, if 2138 * any. 2139 */ 2140 static daddr_t 2141 swp_pager_meta_build(struct pctrie_iter *blks, vm_object_t object, 2142 vm_pindex_t pindex, daddr_t swapblk, bool nowait_noreplace) 2143 { 2144 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 2145 struct swblk *sb, *sb1; 2146 vm_pindex_t modpi; 2147 daddr_t prev_swapblk; 2148 int error, i; 2149 2150 VM_OBJECT_ASSERT_WLOCKED(object); 2151 2152 sb = swblk_iter_lookup(blks, pindex); 2153 if (sb == NULL) { 2154 if (swapblk == SWAPBLK_NONE) 2155 return (SWAPBLK_NONE); 2156 for (;;) { 2157 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 2158 pageproc ? M_USE_RESERVE : 0)); 2159 if (sb != NULL) { 2160 sb->p = rounddown(pindex, SWAP_META_PAGES); 2161 for (i = 0; i < SWAP_META_PAGES; i++) 2162 sb->d[i] = SWAPBLK_NONE; 2163 if (atomic_cmpset_int(&swblk_zone_exhausted, 2164 1, 0)) 2165 printf("swblk zone ok\n"); 2166 break; 2167 } 2168 if (nowait_noreplace) 2169 return (swapblk); 2170 VM_OBJECT_WUNLOCK(object); 2171 if (uma_zone_exhausted(swblk_zone)) { 2172 if (atomic_cmpset_int(&swblk_zone_exhausted, 2173 0, 1)) 2174 printf("swap blk zone exhausted, " 2175 "increase kern.maxswzone\n"); 2176 vm_pageout_oom(VM_OOM_SWAPZ); 2177 pause("swzonxb", 10); 2178 } else 2179 uma_zwait(swblk_zone); 2180 VM_OBJECT_WLOCK(object); 2181 sb = swblk_iter_reinit(blks, object, pindex); 2182 if (sb != NULL) 2183 /* 2184 * Somebody swapped out a nearby page, 2185 * allocating swblk at the pindex index, 2186 * while we dropped the object lock. 2187 */ 2188 goto allocated; 2189 } 2190 for (;;) { 2191 error = swblk_iter_insert(blks, sb); 2192 if (error == 0) { 2193 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2194 1, 0)) 2195 printf("swpctrie zone ok\n"); 2196 break; 2197 } 2198 if (nowait_noreplace) { 2199 uma_zfree(swblk_zone, sb); 2200 return (swapblk); 2201 } 2202 VM_OBJECT_WUNLOCK(object); 2203 if (uma_zone_exhausted(swpctrie_zone)) { 2204 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2205 0, 1)) 2206 printf("swap pctrie zone exhausted, " 2207 "increase kern.maxswzone\n"); 2208 vm_pageout_oom(VM_OOM_SWAPZ); 2209 pause("swzonxp", 10); 2210 } else 2211 uma_zwait(swpctrie_zone); 2212 VM_OBJECT_WLOCK(object); 2213 sb1 = swblk_iter_reinit(blks, object, pindex); 2214 if (sb1 != NULL) { 2215 uma_zfree(swblk_zone, sb); 2216 sb = sb1; 2217 goto allocated; 2218 } 2219 } 2220 } 2221 allocated: 2222 MPASS(sb->p == rounddown(pindex, SWAP_META_PAGES)); 2223 2224 modpi = pindex % SWAP_META_PAGES; 2225 /* Return prior contents of metadata. */ 2226 prev_swapblk = sb->d[modpi]; 2227 if (!nowait_noreplace || prev_swapblk == SWAPBLK_NONE) { 2228 /* Enter block into metadata. */ 2229 sb->d[modpi] = swapblk; 2230 2231 /* 2232 * Free the swblk if we end up with the empty page run. 2233 */ 2234 if (swapblk == SWAPBLK_NONE && 2235 swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 2236 swblk_iter_remove(blks); 2237 uma_zfree(swblk_zone, sb); 2238 } 2239 } 2240 return (prev_swapblk); 2241 } 2242 2243 /* 2244 * SWP_PAGER_META_TRANSFER() - transfer a range of blocks in the srcobject's 2245 * swap metadata into dstobject. 2246 * 2247 * Blocks in src that correspond to holes in dst are transferred. Blocks 2248 * in src that correspond to blocks in dst are freed. 2249 */ 2250 static void 2251 swp_pager_meta_transfer(vm_object_t srcobject, vm_object_t dstobject, 2252 vm_pindex_t pindex, vm_pindex_t count) 2253 { 2254 struct pctrie_iter dstblks, srcblks; 2255 struct page_range range; 2256 struct swblk *sb; 2257 daddr_t blk, d[SWAP_META_PAGES]; 2258 vm_pindex_t last; 2259 int d_mask, i, limit, start; 2260 _Static_assert(8 * sizeof(d_mask) >= SWAP_META_PAGES, 2261 "d_mask not big enough"); 2262 2263 VM_OBJECT_ASSERT_WLOCKED(srcobject); 2264 VM_OBJECT_ASSERT_WLOCKED(dstobject); 2265 2266 if (count == 0 || swblk_is_empty(srcobject)) 2267 return; 2268 2269 swp_pager_init_freerange(&range); 2270 d_mask = 0; 2271 last = pindex + count; 2272 swblk_iter_init_only(&dstblks, dstobject); 2273 for (sb = swblk_iter_limit_init(&srcblks, srcobject, pindex, last), 2274 start = swblk_start(sb, pindex); 2275 sb != NULL; sb = swblk_iter_next(&srcblks), start = 0) { 2276 limit = MIN(last - srcblks.index, SWAP_META_PAGES); 2277 for (i = start; i < limit; i++) { 2278 if (sb->d[i] == SWAPBLK_NONE) 2279 continue; 2280 blk = swp_pager_meta_build(&dstblks, dstobject, 2281 srcblks.index + i - pindex, sb->d[i], true); 2282 if (blk == sb->d[i]) { 2283 /* 2284 * Failed memory allocation stopped transfer; 2285 * save this block for transfer with lock 2286 * released. 2287 */ 2288 d[i] = blk; 2289 d_mask |= 1 << i; 2290 } else if (blk != SWAPBLK_NONE) { 2291 /* Dst has a block at pindex, so free block. */ 2292 swp_pager_update_freerange(&range, sb->d[i]); 2293 } 2294 sb->d[i] = SWAPBLK_NONE; 2295 } 2296 if (swp_pager_swblk_empty(sb, 0, start) && 2297 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2298 swblk_iter_remove(&srcblks); 2299 uma_zfree(swblk_zone, sb); 2300 } 2301 if (d_mask != 0) { 2302 /* Finish block transfer, with the lock released. */ 2303 VM_OBJECT_WUNLOCK(srcobject); 2304 do { 2305 i = ffs(d_mask) - 1; 2306 swp_pager_meta_build(&dstblks, dstobject, 2307 srcblks.index + i - pindex, d[i], false); 2308 d_mask &= ~(1 << i); 2309 } while (d_mask != 0); 2310 VM_OBJECT_WLOCK(srcobject); 2311 2312 /* 2313 * While the lock was not held, the iterator path could 2314 * have become stale, so discard it. 2315 */ 2316 pctrie_iter_reset(&srcblks); 2317 } 2318 } 2319 swp_pager_freeswapspace(&range); 2320 } 2321 2322 /* 2323 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2324 * 2325 * Return freed swap blocks to the swap bitmap, and free emptied swblk 2326 * metadata. With 'freed' set, provide a count of freed blocks that were 2327 * not associated with valid resident pages. 2328 */ 2329 static void 2330 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count, 2331 vm_size_t *freed) 2332 { 2333 struct pctrie_iter blks, pages; 2334 struct page_range range; 2335 struct swblk *sb; 2336 vm_page_t m; 2337 vm_pindex_t last; 2338 vm_size_t fc; 2339 int i, limit, start; 2340 2341 VM_OBJECT_ASSERT_WLOCKED(object); 2342 2343 fc = 0; 2344 if (count == 0 || swblk_is_empty(object)) 2345 goto out; 2346 2347 swp_pager_init_freerange(&range); 2348 vm_page_iter_init(&pages, object); 2349 last = pindex + count; 2350 for (sb = swblk_iter_limit_init(&blks, object, pindex, last), 2351 start = swblk_start(sb, pindex); 2352 sb != NULL; sb = swblk_iter_next(&blks), start = 0) { 2353 limit = MIN(last - blks.index, SWAP_META_PAGES); 2354 for (i = start; i < limit; i++) { 2355 if (sb->d[i] == SWAPBLK_NONE) 2356 continue; 2357 swp_pager_update_freerange(&range, sb->d[i]); 2358 if (freed != NULL) { 2359 m = vm_page_iter_lookup(&pages, blks.index + i); 2360 if (m == NULL || vm_page_none_valid(m)) 2361 fc++; 2362 } 2363 sb->d[i] = SWAPBLK_NONE; 2364 } 2365 if (swp_pager_swblk_empty(sb, 0, start) && 2366 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2367 swblk_iter_remove(&blks); 2368 uma_zfree(swblk_zone, sb); 2369 } 2370 } 2371 swp_pager_freeswapspace(&range); 2372 out: 2373 if (freed != NULL) 2374 *freed = fc; 2375 } 2376 2377 static void 2378 swp_pager_meta_free_block(struct swblk *sb, void *rangev) 2379 { 2380 struct page_range *range = rangev; 2381 2382 for (int i = 0; i < SWAP_META_PAGES; i++) { 2383 if (sb->d[i] != SWAPBLK_NONE) 2384 swp_pager_update_freerange(range, sb->d[i]); 2385 } 2386 uma_zfree(swblk_zone, sb); 2387 } 2388 2389 /* 2390 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2391 * 2392 * This routine locates and destroys all swap metadata associated with 2393 * an object. 2394 */ 2395 static void 2396 swp_pager_meta_free_all(vm_object_t object) 2397 { 2398 struct page_range range; 2399 2400 VM_OBJECT_ASSERT_WLOCKED(object); 2401 2402 swp_pager_init_freerange(&range); 2403 SWAP_PCTRIE_RECLAIM_CALLBACK(&object->un_pager.swp.swp_blks, 2404 swp_pager_meta_free_block, &range); 2405 swp_pager_freeswapspace(&range); 2406 } 2407 2408 /* 2409 * SWP_PAGER_METACTL() - misc control of swap meta data. 2410 * 2411 * This routine is capable of looking up, or removing swapblk 2412 * assignments in the swap meta data. It returns the swapblk being 2413 * looked-up, popped, or SWAPBLK_NONE if the block was invalid. 2414 * 2415 * When acting on a busy resident page and paging is in progress, we 2416 * have to wait until paging is complete but otherwise can act on the 2417 * busy page. 2418 */ 2419 static daddr_t 2420 swp_pager_meta_lookup(vm_object_t object, vm_pindex_t pindex) 2421 { 2422 struct swblk *sb; 2423 2424 VM_OBJECT_ASSERT_LOCKED(object); 2425 2426 /* 2427 * The meta data only exists if the object is OBJT_SWAP 2428 * and even then might not be allocated yet. 2429 */ 2430 KASSERT((object->flags & OBJ_SWAP) != 0, 2431 ("Lookup object not swappable")); 2432 2433 sb = swblk_lookup(object, pindex); 2434 if (sb == NULL) 2435 return (SWAPBLK_NONE); 2436 return (sb->d[pindex % SWAP_META_PAGES]); 2437 } 2438 2439 /* 2440 * Returns the least page index which is greater than or equal to the parameter 2441 * pindex and for which there is a swap block allocated. Returns OBJ_MAX_SIZE 2442 * if are no allocated swap blocks for the object after the requested pindex. 2443 */ 2444 vm_pindex_t 2445 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2446 { 2447 struct pctrie_iter blks; 2448 struct swblk *sb; 2449 int i; 2450 2451 if ((sb = swblk_iter_init(&blks, object, pindex)) == NULL) 2452 return (OBJ_MAX_SIZE); 2453 if (blks.index < pindex) { 2454 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2455 if (sb->d[i] != SWAPBLK_NONE) 2456 return (blks.index + i); 2457 } 2458 if ((sb = swblk_iter_next(&blks)) == NULL) 2459 return (OBJ_MAX_SIZE); 2460 } 2461 for (i = 0; i < SWAP_META_PAGES; i++) { 2462 if (sb->d[i] != SWAPBLK_NONE) 2463 return (blks.index + i); 2464 } 2465 2466 /* 2467 * We get here if a swblk is present in the trie but it 2468 * doesn't map any blocks. 2469 */ 2470 MPASS(0); 2471 return (OBJ_MAX_SIZE); 2472 } 2473 2474 /* 2475 * System call swapon(name) enables swapping on device name, 2476 * which must be in the swdevsw. Return EBUSY 2477 * if already swapping on this device. 2478 */ 2479 #ifndef _SYS_SYSPROTO_H_ 2480 struct swapon_args { 2481 char *name; 2482 }; 2483 #endif 2484 2485 int 2486 sys_swapon(struct thread *td, struct swapon_args *uap) 2487 { 2488 struct vattr attr; 2489 struct vnode *vp; 2490 struct nameidata nd; 2491 int error; 2492 2493 error = priv_check(td, PRIV_SWAPON); 2494 if (error) 2495 return (error); 2496 2497 sx_xlock(&swdev_syscall_lock); 2498 2499 /* 2500 * Swap metadata may not fit in the KVM if we have physical 2501 * memory of >1GB. 2502 */ 2503 if (swblk_zone == NULL) { 2504 error = ENOMEM; 2505 goto done; 2506 } 2507 2508 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | LOCKLEAF | AUDITVNODE1, 2509 UIO_USERSPACE, uap->name); 2510 error = namei(&nd); 2511 if (error) 2512 goto done; 2513 2514 NDFREE_PNBUF(&nd); 2515 vp = nd.ni_vp; 2516 2517 if (vn_isdisk_error(vp, &error)) { 2518 error = swapongeom(vp); 2519 } else if (vp->v_type == VREG && 2520 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2521 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2522 /* 2523 * Allow direct swapping to NFS regular files in the same 2524 * way that nfs_mountroot() sets up diskless swapping. 2525 */ 2526 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2527 } 2528 2529 if (error != 0) 2530 vput(vp); 2531 else 2532 VOP_UNLOCK(vp); 2533 done: 2534 sx_xunlock(&swdev_syscall_lock); 2535 return (error); 2536 } 2537 2538 /* 2539 * Check that the total amount of swap currently configured does not 2540 * exceed half the theoretical maximum. If it does, print a warning 2541 * message. 2542 */ 2543 static void 2544 swapon_check_swzone(void) 2545 { 2546 2547 /* recommend using no more than half that amount */ 2548 if (swap_total > swap_maxpages / 2) { 2549 printf("warning: total configured swap (%lu pages) " 2550 "exceeds maximum recommended amount (%lu pages).\n", 2551 swap_total, swap_maxpages / 2); 2552 printf("warning: increase kern.maxswzone " 2553 "or reduce amount of swap.\n"); 2554 } 2555 } 2556 2557 static void 2558 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2559 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2560 { 2561 struct swdevt *sp, *tsp; 2562 daddr_t dvbase; 2563 2564 /* 2565 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2566 * First chop nblks off to page-align it, then convert. 2567 * 2568 * sw->sw_nblks is in page-sized chunks now too. 2569 */ 2570 nblks &= ~(ctodb(1) - 1); 2571 nblks = dbtoc(nblks); 2572 2573 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2574 sp->sw_blist = blist_create(nblks, M_WAITOK); 2575 sp->sw_vp = vp; 2576 sp->sw_id = id; 2577 sp->sw_dev = dev; 2578 sp->sw_nblks = nblks; 2579 sp->sw_used = 0; 2580 sp->sw_strategy = strategy; 2581 sp->sw_close = close; 2582 sp->sw_flags = flags; 2583 2584 /* 2585 * Do not free the first blocks in order to avoid overwriting 2586 * any bsd label at the front of the partition 2587 */ 2588 blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE), 2589 nblks - howmany(BBSIZE, PAGE_SIZE)); 2590 2591 dvbase = 0; 2592 mtx_lock(&sw_dev_mtx); 2593 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2594 if (tsp->sw_end >= dvbase) { 2595 /* 2596 * We put one uncovered page between the devices 2597 * in order to definitively prevent any cross-device 2598 * I/O requests 2599 */ 2600 dvbase = tsp->sw_end + 1; 2601 } 2602 } 2603 sp->sw_first = dvbase; 2604 sp->sw_end = dvbase + nblks; 2605 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2606 nswapdev++; 2607 swap_pager_avail += nblks - howmany(BBSIZE, PAGE_SIZE); 2608 swap_total += nblks; 2609 swapon_check_swzone(); 2610 swp_sizecheck(); 2611 mtx_unlock(&sw_dev_mtx); 2612 EVENTHANDLER_INVOKE(swapon, sp); 2613 } 2614 2615 /* 2616 * SYSCALL: swapoff(devname) 2617 * 2618 * Disable swapping on the given device. 2619 * 2620 * XXX: Badly designed system call: it should use a device index 2621 * rather than filename as specification. We keep sw_vp around 2622 * only to make this work. 2623 */ 2624 static int 2625 kern_swapoff(struct thread *td, const char *name, enum uio_seg name_seg, 2626 u_int flags) 2627 { 2628 struct vnode *vp; 2629 struct nameidata nd; 2630 struct swdevt *sp; 2631 int error; 2632 2633 error = priv_check(td, PRIV_SWAPOFF); 2634 if (error != 0) 2635 return (error); 2636 if ((flags & ~(SWAPOFF_FORCE)) != 0) 2637 return (EINVAL); 2638 2639 sx_xlock(&swdev_syscall_lock); 2640 2641 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, name_seg, name); 2642 error = namei(&nd); 2643 if (error) 2644 goto done; 2645 NDFREE_PNBUF(&nd); 2646 vp = nd.ni_vp; 2647 2648 mtx_lock(&sw_dev_mtx); 2649 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2650 if (sp->sw_vp == vp) 2651 break; 2652 } 2653 mtx_unlock(&sw_dev_mtx); 2654 if (sp == NULL) { 2655 error = EINVAL; 2656 goto done; 2657 } 2658 error = swapoff_one(sp, td->td_ucred, flags); 2659 done: 2660 sx_xunlock(&swdev_syscall_lock); 2661 return (error); 2662 } 2663 2664 2665 #ifdef COMPAT_FREEBSD13 2666 int 2667 freebsd13_swapoff(struct thread *td, struct freebsd13_swapoff_args *uap) 2668 { 2669 return (kern_swapoff(td, uap->name, UIO_USERSPACE, 0)); 2670 } 2671 #endif 2672 2673 int 2674 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2675 { 2676 return (kern_swapoff(td, uap->name, UIO_USERSPACE, uap->flags)); 2677 } 2678 2679 static int 2680 swapoff_one(struct swdevt *sp, struct ucred *cred, u_int flags) 2681 { 2682 u_long nblks; 2683 #ifdef MAC 2684 int error; 2685 #endif 2686 2687 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2688 #ifdef MAC 2689 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2690 error = mac_system_check_swapoff(cred, sp->sw_vp); 2691 (void) VOP_UNLOCK(sp->sw_vp); 2692 if (error != 0) 2693 return (error); 2694 #endif 2695 nblks = sp->sw_nblks; 2696 2697 /* 2698 * We can turn off this swap device safely only if the 2699 * available virtual memory in the system will fit the amount 2700 * of data we will have to page back in, plus an epsilon so 2701 * the system doesn't become critically low on swap space. 2702 * The vm_free_count() part does not account e.g. for clean 2703 * pages that can be immediately reclaimed without paging, so 2704 * this is a very rough estimation. 2705 * 2706 * On the other hand, not turning swap off on swapoff_all() 2707 * means that we can lose swap data when filesystems go away, 2708 * which is arguably worse. 2709 */ 2710 if ((flags & SWAPOFF_FORCE) == 0 && 2711 vm_free_count() + swap_pager_avail < nblks + nswap_lowat) 2712 return (ENOMEM); 2713 2714 /* 2715 * Prevent further allocations on this device. 2716 */ 2717 mtx_lock(&sw_dev_mtx); 2718 sp->sw_flags |= SW_CLOSING; 2719 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2720 swap_total -= nblks; 2721 mtx_unlock(&sw_dev_mtx); 2722 2723 /* 2724 * Page in the contents of the device and close it. 2725 */ 2726 swap_pager_swapoff(sp); 2727 2728 sp->sw_close(curthread, sp); 2729 mtx_lock(&sw_dev_mtx); 2730 sp->sw_id = NULL; 2731 TAILQ_REMOVE(&swtailq, sp, sw_list); 2732 nswapdev--; 2733 if (nswapdev == 0) { 2734 swap_pager_full = 2; 2735 swap_pager_almost_full = 1; 2736 } 2737 if (swdevhd == sp) 2738 swdevhd = NULL; 2739 mtx_unlock(&sw_dev_mtx); 2740 blist_destroy(sp->sw_blist); 2741 free(sp, M_VMPGDATA); 2742 return (0); 2743 } 2744 2745 void 2746 swapoff_all(void) 2747 { 2748 struct swdevt *sp, *spt; 2749 const char *devname; 2750 int error; 2751 2752 sx_xlock(&swdev_syscall_lock); 2753 2754 mtx_lock(&sw_dev_mtx); 2755 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2756 mtx_unlock(&sw_dev_mtx); 2757 if (vn_isdisk(sp->sw_vp)) 2758 devname = devtoname(sp->sw_vp->v_rdev); 2759 else 2760 devname = "[file]"; 2761 error = swapoff_one(sp, thread0.td_ucred, SWAPOFF_FORCE); 2762 if (error != 0) { 2763 printf("Cannot remove swap device %s (error=%d), " 2764 "skipping.\n", devname, error); 2765 } else if (bootverbose) { 2766 printf("Swap device %s removed.\n", devname); 2767 } 2768 mtx_lock(&sw_dev_mtx); 2769 } 2770 mtx_unlock(&sw_dev_mtx); 2771 2772 sx_xunlock(&swdev_syscall_lock); 2773 } 2774 2775 void 2776 swap_pager_status(int *total, int *used) 2777 { 2778 2779 *total = swap_total; 2780 *used = swap_total - swap_pager_avail - 2781 nswapdev * howmany(BBSIZE, PAGE_SIZE); 2782 } 2783 2784 int 2785 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2786 { 2787 struct swdevt *sp; 2788 const char *tmp_devname; 2789 int error, n; 2790 2791 n = 0; 2792 error = ENOENT; 2793 mtx_lock(&sw_dev_mtx); 2794 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2795 if (n != name) { 2796 n++; 2797 continue; 2798 } 2799 xs->xsw_version = XSWDEV_VERSION; 2800 xs->xsw_dev = sp->sw_dev; 2801 xs->xsw_flags = sp->sw_flags; 2802 xs->xsw_nblks = sp->sw_nblks; 2803 xs->xsw_used = sp->sw_used; 2804 if (devname != NULL) { 2805 if (vn_isdisk(sp->sw_vp)) 2806 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2807 else 2808 tmp_devname = "[file]"; 2809 strncpy(devname, tmp_devname, len); 2810 } 2811 error = 0; 2812 break; 2813 } 2814 mtx_unlock(&sw_dev_mtx); 2815 return (error); 2816 } 2817 2818 #if defined(COMPAT_FREEBSD11) 2819 #define XSWDEV_VERSION_11 1 2820 struct xswdev11 { 2821 u_int xsw_version; 2822 uint32_t xsw_dev; 2823 int xsw_flags; 2824 int xsw_nblks; 2825 int xsw_used; 2826 }; 2827 #endif 2828 2829 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2830 struct xswdev32 { 2831 u_int xsw_version; 2832 u_int xsw_dev1, xsw_dev2; 2833 int xsw_flags; 2834 int xsw_nblks; 2835 int xsw_used; 2836 }; 2837 #endif 2838 2839 static int 2840 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2841 { 2842 struct xswdev xs; 2843 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2844 struct xswdev32 xs32; 2845 #endif 2846 #if defined(COMPAT_FREEBSD11) 2847 struct xswdev11 xs11; 2848 #endif 2849 int error; 2850 2851 if (arg2 != 1) /* name length */ 2852 return (EINVAL); 2853 2854 memset(&xs, 0, sizeof(xs)); 2855 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2856 if (error != 0) 2857 return (error); 2858 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2859 if (req->oldlen == sizeof(xs32)) { 2860 memset(&xs32, 0, sizeof(xs32)); 2861 xs32.xsw_version = XSWDEV_VERSION; 2862 xs32.xsw_dev1 = xs.xsw_dev; 2863 xs32.xsw_dev2 = xs.xsw_dev >> 32; 2864 xs32.xsw_flags = xs.xsw_flags; 2865 xs32.xsw_nblks = xs.xsw_nblks; 2866 xs32.xsw_used = xs.xsw_used; 2867 error = SYSCTL_OUT(req, &xs32, sizeof(xs32)); 2868 return (error); 2869 } 2870 #endif 2871 #if defined(COMPAT_FREEBSD11) 2872 if (req->oldlen == sizeof(xs11)) { 2873 memset(&xs11, 0, sizeof(xs11)); 2874 xs11.xsw_version = XSWDEV_VERSION_11; 2875 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2876 xs11.xsw_flags = xs.xsw_flags; 2877 xs11.xsw_nblks = xs.xsw_nblks; 2878 xs11.xsw_used = xs.xsw_used; 2879 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2880 return (error); 2881 } 2882 #endif 2883 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2884 return (error); 2885 } 2886 2887 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2888 "Number of swap devices"); 2889 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2890 sysctl_vm_swap_info, 2891 "Swap statistics by device"); 2892 2893 /* 2894 * Count the approximate swap usage in pages for a vmspace. The 2895 * shadowed or not yet copied on write swap blocks are not accounted. 2896 * The map must be locked. 2897 */ 2898 long 2899 vmspace_swap_count(struct vmspace *vmspace) 2900 { 2901 struct pctrie_iter blks; 2902 vm_map_t map; 2903 vm_map_entry_t cur; 2904 vm_object_t object; 2905 struct swblk *sb; 2906 vm_pindex_t e, pi; 2907 long count; 2908 int i, limit, start; 2909 2910 map = &vmspace->vm_map; 2911 count = 0; 2912 2913 VM_MAP_ENTRY_FOREACH(cur, map) { 2914 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 2915 continue; 2916 object = cur->object.vm_object; 2917 if (object == NULL || (object->flags & OBJ_SWAP) == 0) 2918 continue; 2919 VM_OBJECT_RLOCK(object); 2920 if ((object->flags & OBJ_SWAP) == 0) 2921 goto unlock; 2922 pi = OFF_TO_IDX(cur->offset); 2923 e = pi + OFF_TO_IDX(cur->end - cur->start); 2924 for (sb = swblk_iter_limit_init(&blks, object, pi, e), 2925 start = swblk_start(sb, pi); 2926 sb != NULL; sb = swblk_iter_next(&blks), start = 0) { 2927 limit = MIN(e - blks.index, SWAP_META_PAGES); 2928 for (i = start; i < limit; i++) { 2929 if (sb->d[i] != SWAPBLK_NONE) 2930 count++; 2931 } 2932 } 2933 unlock: 2934 VM_OBJECT_RUNLOCK(object); 2935 } 2936 return (count); 2937 } 2938 2939 /* 2940 * GEOM backend 2941 * 2942 * Swapping onto disk devices. 2943 * 2944 */ 2945 2946 static g_orphan_t swapgeom_orphan; 2947 2948 static struct g_class g_swap_class = { 2949 .name = "SWAP", 2950 .version = G_VERSION, 2951 .orphan = swapgeom_orphan, 2952 }; 2953 2954 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2955 2956 static void 2957 swapgeom_close_ev(void *arg, int flags) 2958 { 2959 struct g_consumer *cp; 2960 2961 cp = arg; 2962 g_access(cp, -1, -1, 0); 2963 g_detach(cp); 2964 g_destroy_consumer(cp); 2965 } 2966 2967 /* 2968 * Add a reference to the g_consumer for an inflight transaction. 2969 */ 2970 static void 2971 swapgeom_acquire(struct g_consumer *cp) 2972 { 2973 2974 mtx_assert(&sw_dev_mtx, MA_OWNED); 2975 cp->index++; 2976 } 2977 2978 /* 2979 * Remove a reference from the g_consumer. Post a close event if all 2980 * references go away, since the function might be called from the 2981 * biodone context. 2982 */ 2983 static void 2984 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2985 { 2986 2987 mtx_assert(&sw_dev_mtx, MA_OWNED); 2988 cp->index--; 2989 if (cp->index == 0) { 2990 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2991 sp->sw_id = NULL; 2992 } 2993 } 2994 2995 static void 2996 swapgeom_done(struct bio *bp2) 2997 { 2998 struct swdevt *sp; 2999 struct buf *bp; 3000 struct g_consumer *cp; 3001 3002 bp = bp2->bio_caller2; 3003 cp = bp2->bio_from; 3004 bp->b_ioflags = bp2->bio_flags; 3005 if (bp2->bio_error) 3006 bp->b_ioflags |= BIO_ERROR; 3007 bp->b_resid = bp->b_bcount - bp2->bio_completed; 3008 bp->b_error = bp2->bio_error; 3009 bp->b_caller1 = NULL; 3010 bufdone(bp); 3011 sp = bp2->bio_caller1; 3012 mtx_lock(&sw_dev_mtx); 3013 swapgeom_release(cp, sp); 3014 mtx_unlock(&sw_dev_mtx); 3015 g_destroy_bio(bp2); 3016 } 3017 3018 static void 3019 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 3020 { 3021 struct bio *bio; 3022 struct g_consumer *cp; 3023 3024 mtx_lock(&sw_dev_mtx); 3025 cp = sp->sw_id; 3026 if (cp == NULL) { 3027 mtx_unlock(&sw_dev_mtx); 3028 bp->b_error = ENXIO; 3029 bp->b_ioflags |= BIO_ERROR; 3030 bufdone(bp); 3031 return; 3032 } 3033 swapgeom_acquire(cp); 3034 mtx_unlock(&sw_dev_mtx); 3035 if (bp->b_iocmd == BIO_WRITE) 3036 bio = g_new_bio(); 3037 else 3038 bio = g_alloc_bio(); 3039 if (bio == NULL) { 3040 mtx_lock(&sw_dev_mtx); 3041 swapgeom_release(cp, sp); 3042 mtx_unlock(&sw_dev_mtx); 3043 bp->b_error = ENOMEM; 3044 bp->b_ioflags |= BIO_ERROR; 3045 printf("swap_pager: cannot allocate bio\n"); 3046 bufdone(bp); 3047 return; 3048 } 3049 3050 bp->b_caller1 = bio; 3051 bio->bio_caller1 = sp; 3052 bio->bio_caller2 = bp; 3053 bio->bio_cmd = bp->b_iocmd; 3054 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 3055 bio->bio_length = bp->b_bcount; 3056 bio->bio_done = swapgeom_done; 3057 bio->bio_flags |= BIO_SWAP; 3058 if (!buf_mapped(bp)) { 3059 bio->bio_ma = bp->b_pages; 3060 bio->bio_data = unmapped_buf; 3061 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 3062 bio->bio_ma_n = bp->b_npages; 3063 bio->bio_flags |= BIO_UNMAPPED; 3064 } else { 3065 bio->bio_data = bp->b_data; 3066 bio->bio_ma = NULL; 3067 } 3068 g_io_request(bio, cp); 3069 return; 3070 } 3071 3072 static void 3073 swapgeom_orphan(struct g_consumer *cp) 3074 { 3075 struct swdevt *sp; 3076 int destroy; 3077 3078 mtx_lock(&sw_dev_mtx); 3079 TAILQ_FOREACH(sp, &swtailq, sw_list) { 3080 if (sp->sw_id == cp) { 3081 sp->sw_flags |= SW_CLOSING; 3082 break; 3083 } 3084 } 3085 /* 3086 * Drop reference we were created with. Do directly since we're in a 3087 * special context where we don't have to queue the call to 3088 * swapgeom_close_ev(). 3089 */ 3090 cp->index--; 3091 destroy = ((sp != NULL) && (cp->index == 0)); 3092 if (destroy) 3093 sp->sw_id = NULL; 3094 mtx_unlock(&sw_dev_mtx); 3095 if (destroy) 3096 swapgeom_close_ev(cp, 0); 3097 } 3098 3099 static void 3100 swapgeom_close(struct thread *td, struct swdevt *sw) 3101 { 3102 struct g_consumer *cp; 3103 3104 mtx_lock(&sw_dev_mtx); 3105 cp = sw->sw_id; 3106 sw->sw_id = NULL; 3107 mtx_unlock(&sw_dev_mtx); 3108 3109 /* 3110 * swapgeom_close() may be called from the biodone context, 3111 * where we cannot perform topology changes. Delegate the 3112 * work to the events thread. 3113 */ 3114 if (cp != NULL) 3115 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 3116 } 3117 3118 static int 3119 swapongeom_locked(struct cdev *dev, struct vnode *vp) 3120 { 3121 struct g_provider *pp; 3122 struct g_consumer *cp; 3123 static struct g_geom *gp; 3124 struct swdevt *sp; 3125 u_long nblks; 3126 int error; 3127 3128 pp = g_dev_getprovider(dev); 3129 if (pp == NULL) 3130 return (ENODEV); 3131 mtx_lock(&sw_dev_mtx); 3132 TAILQ_FOREACH(sp, &swtailq, sw_list) { 3133 cp = sp->sw_id; 3134 if (cp != NULL && cp->provider == pp) { 3135 mtx_unlock(&sw_dev_mtx); 3136 return (EBUSY); 3137 } 3138 } 3139 mtx_unlock(&sw_dev_mtx); 3140 if (gp == NULL) 3141 gp = g_new_geomf(&g_swap_class, "swap"); 3142 cp = g_new_consumer(gp); 3143 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 3144 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 3145 g_attach(cp, pp); 3146 /* 3147 * XXX: Every time you think you can improve the margin for 3148 * footshooting, somebody depends on the ability to do so: 3149 * savecore(8) wants to write to our swapdev so we cannot 3150 * set an exclusive count :-( 3151 */ 3152 error = g_access(cp, 1, 1, 0); 3153 if (error != 0) { 3154 g_detach(cp); 3155 g_destroy_consumer(cp); 3156 return (error); 3157 } 3158 nblks = pp->mediasize / DEV_BSIZE; 3159 swaponsomething(vp, cp, nblks, swapgeom_strategy, 3160 swapgeom_close, dev2udev(dev), 3161 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 3162 return (0); 3163 } 3164 3165 static int 3166 swapongeom(struct vnode *vp) 3167 { 3168 int error; 3169 3170 ASSERT_VOP_ELOCKED(vp, "swapongeom"); 3171 if (vp->v_type != VCHR || VN_IS_DOOMED(vp)) { 3172 error = ENOENT; 3173 } else { 3174 g_topology_lock(); 3175 error = swapongeom_locked(vp->v_rdev, vp); 3176 g_topology_unlock(); 3177 } 3178 return (error); 3179 } 3180 3181 /* 3182 * VNODE backend 3183 * 3184 * This is used mainly for network filesystem (read: probably only tested 3185 * with NFS) swapfiles. 3186 * 3187 */ 3188 3189 static void 3190 swapdev_strategy(struct buf *bp, struct swdevt *sp) 3191 { 3192 struct vnode *vp2; 3193 3194 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 3195 3196 vp2 = sp->sw_id; 3197 vhold(vp2); 3198 if (bp->b_iocmd == BIO_WRITE) { 3199 vn_lock(vp2, LK_EXCLUSIVE | LK_RETRY); 3200 if (bp->b_bufobj) 3201 bufobj_wdrop(bp->b_bufobj); 3202 bufobj_wref(&vp2->v_bufobj); 3203 } else { 3204 vn_lock(vp2, LK_SHARED | LK_RETRY); 3205 } 3206 if (bp->b_bufobj != &vp2->v_bufobj) 3207 bp->b_bufobj = &vp2->v_bufobj; 3208 bp->b_vp = vp2; 3209 bp->b_iooffset = dbtob(bp->b_blkno); 3210 bstrategy(bp); 3211 VOP_UNLOCK(vp2); 3212 } 3213 3214 static void 3215 swapdev_close(struct thread *td, struct swdevt *sp) 3216 { 3217 struct vnode *vp; 3218 3219 vp = sp->sw_vp; 3220 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 3221 VOP_CLOSE(vp, FREAD | FWRITE, td->td_ucred, td); 3222 vput(vp); 3223 } 3224 3225 static int 3226 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 3227 { 3228 struct swdevt *sp; 3229 int error; 3230 3231 ASSERT_VOP_ELOCKED(vp, "swaponvp"); 3232 if (nblks == 0) 3233 return (ENXIO); 3234 mtx_lock(&sw_dev_mtx); 3235 TAILQ_FOREACH(sp, &swtailq, sw_list) { 3236 if (sp->sw_id == vp) { 3237 mtx_unlock(&sw_dev_mtx); 3238 return (EBUSY); 3239 } 3240 } 3241 mtx_unlock(&sw_dev_mtx); 3242 3243 #ifdef MAC 3244 error = mac_system_check_swapon(td->td_ucred, vp); 3245 if (error == 0) 3246 #endif 3247 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 3248 if (error != 0) 3249 return (error); 3250 3251 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 3252 NODEV, 0); 3253 return (0); 3254 } 3255 3256 static int 3257 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 3258 { 3259 int error, new, n; 3260 3261 new = nsw_wcount_async_max; 3262 error = sysctl_handle_int(oidp, &new, 0, req); 3263 if (error != 0 || req->newptr == NULL) 3264 return (error); 3265 3266 if (new > nswbuf / 2 || new < 1) 3267 return (EINVAL); 3268 3269 mtx_lock(&swbuf_mtx); 3270 while (nsw_wcount_async_max != new) { 3271 /* 3272 * Adjust difference. If the current async count is too low, 3273 * we will need to sqeeze our update slowly in. Sleep with a 3274 * higher priority than getpbuf() to finish faster. 3275 */ 3276 n = new - nsw_wcount_async_max; 3277 if (nsw_wcount_async + n >= 0) { 3278 nsw_wcount_async += n; 3279 nsw_wcount_async_max += n; 3280 wakeup(&nsw_wcount_async); 3281 } else { 3282 nsw_wcount_async_max -= nsw_wcount_async; 3283 nsw_wcount_async = 0; 3284 msleep(&nsw_wcount_async, &swbuf_mtx, PSWP, 3285 "swpsysctl", 0); 3286 } 3287 } 3288 mtx_unlock(&swbuf_mtx); 3289 3290 return (0); 3291 } 3292 3293 static void 3294 swap_pager_update_writecount(vm_object_t object, vm_offset_t start, 3295 vm_offset_t end) 3296 { 3297 3298 VM_OBJECT_WLOCK(object); 3299 KASSERT((object->flags & OBJ_ANON) == 0, 3300 ("Splittable object with writecount")); 3301 object->un_pager.swp.writemappings += (vm_ooffset_t)end - start; 3302 VM_OBJECT_WUNLOCK(object); 3303 } 3304 3305 static void 3306 swap_pager_release_writecount(vm_object_t object, vm_offset_t start, 3307 vm_offset_t end) 3308 { 3309 3310 VM_OBJECT_WLOCK(object); 3311 KASSERT((object->flags & OBJ_ANON) == 0, 3312 ("Splittable object with writecount")); 3313 KASSERT(object->un_pager.swp.writemappings >= (vm_ooffset_t)end - start, 3314 ("swap obj %p writecount %jx dec %jx", object, 3315 (uintmax_t)object->un_pager.swp.writemappings, 3316 (uintmax_t)((vm_ooffset_t)end - start))); 3317 object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start; 3318 VM_OBJECT_WUNLOCK(object); 3319 } 3320