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/vm_radix.h> 115 #include <vm/swap_pager.h> 116 #include <vm/vm_extern.h> 117 #include <vm/uma.h> 118 119 #include <geom/geom.h> 120 121 /* 122 * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64. 123 * The 64-page limit is due to the radix code (kern/subr_blist.c). 124 */ 125 #ifndef MAX_PAGEOUT_CLUSTER 126 #define MAX_PAGEOUT_CLUSTER 32 127 #endif 128 129 #if !defined(SWB_NPAGES) 130 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER 131 #endif 132 133 #define SWAP_META_PAGES PCTRIE_COUNT 134 135 /* 136 * A swblk structure maps each page index within a 137 * SWAP_META_PAGES-aligned and sized range to the address of an 138 * on-disk swap block (or SWAPBLK_NONE). The collection of these 139 * mappings for an entire vm object is implemented as a pc-trie. 140 */ 141 struct swblk { 142 vm_pindex_t p; 143 daddr_t d[SWAP_META_PAGES]; 144 }; 145 146 /* 147 * A page_range structure records the start address and length of a sequence of 148 * mapped page addresses. 149 */ 150 struct page_range { 151 daddr_t start; 152 daddr_t num; 153 }; 154 155 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); 156 static struct mtx sw_dev_mtx; 157 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 158 static struct swdevt *swdevhd; /* Allocate from here next */ 159 static int nswapdev; /* Number of swap devices */ 160 int swap_pager_avail; 161 static struct sx swdev_syscall_lock; /* serialize swap(on|off) */ 162 163 static __exclusive_cache_line u_long swap_reserved; 164 static u_long swap_total; 165 static int sysctl_page_shift(SYSCTL_HANDLER_ARGS); 166 167 static SYSCTL_NODE(_vm_stats, OID_AUTO, swap, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 168 "VM swap stats"); 169 170 SYSCTL_PROC(_vm, OID_AUTO, swap_reserved, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 171 &swap_reserved, 0, sysctl_page_shift, "QU", 172 "Amount of swap storage needed to back all allocated anonymous memory."); 173 SYSCTL_PROC(_vm, OID_AUTO, swap_total, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 174 &swap_total, 0, sysctl_page_shift, "QU", 175 "Total amount of available swap storage."); 176 177 int vm_overcommit __read_mostly = 0; 178 SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &vm_overcommit, 0, 179 "Configure virtual memory overcommit behavior. See tuning(7) " 180 "for details."); 181 static unsigned long swzone; 182 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 183 "Actual size of swap metadata zone"); 184 static unsigned long swap_maxpages; 185 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, 186 "Maximum amount of swap supported"); 187 188 static COUNTER_U64_DEFINE_EARLY(swap_free_deferred); 189 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_deferred, 190 CTLFLAG_RD, &swap_free_deferred, 191 "Number of pages that deferred freeing swap space"); 192 193 static COUNTER_U64_DEFINE_EARLY(swap_free_completed); 194 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_completed, 195 CTLFLAG_RD, &swap_free_completed, 196 "Number of deferred frees completed"); 197 198 static int 199 sysctl_page_shift(SYSCTL_HANDLER_ARGS) 200 { 201 uint64_t newval; 202 u_long value = *(u_long *)arg1; 203 204 newval = ((uint64_t)value) << PAGE_SHIFT; 205 return (sysctl_handle_64(oidp, &newval, 0, req)); 206 } 207 208 static bool 209 swap_reserve_by_cred_rlimit(u_long pincr, struct ucred *cred, int oc) 210 { 211 struct uidinfo *uip; 212 u_long prev; 213 214 uip = cred->cr_ruidinfo; 215 216 prev = atomic_fetchadd_long(&uip->ui_vmsize, pincr); 217 if ((oc & SWAP_RESERVE_RLIMIT_ON) != 0 && 218 prev + pincr > lim_cur(curthread, RLIMIT_SWAP) && 219 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT) != 0) { 220 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pincr); 221 KASSERT(prev >= pincr, 222 ("negative vmsize for uid %d\n", uip->ui_uid)); 223 return (false); 224 } 225 return (true); 226 } 227 228 static void 229 swap_release_by_cred_rlimit(u_long pdecr, struct ucred *cred) 230 { 231 struct uidinfo *uip; 232 #ifdef INVARIANTS 233 u_long prev; 234 #endif 235 236 uip = cred->cr_ruidinfo; 237 238 #ifdef INVARIANTS 239 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pdecr); 240 KASSERT(prev >= pdecr, 241 ("negative vmsize for uid %d\n", uip->ui_uid)); 242 #else 243 atomic_subtract_long(&uip->ui_vmsize, pdecr); 244 #endif 245 } 246 247 static void 248 swap_reserve_force_rlimit(u_long pincr, struct ucred *cred) 249 { 250 struct uidinfo *uip; 251 252 uip = cred->cr_ruidinfo; 253 atomic_add_long(&uip->ui_vmsize, pincr); 254 } 255 256 bool 257 swap_reserve(vm_ooffset_t incr) 258 { 259 260 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 261 } 262 263 bool 264 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 265 { 266 u_long r, s, prev, pincr; 267 #ifdef RACCT 268 int error; 269 #endif 270 int oc; 271 static int curfail; 272 static struct timeval lastfail; 273 274 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", 275 __func__, (uintmax_t)incr)); 276 277 #ifdef RACCT 278 if (RACCT_ENABLED()) { 279 PROC_LOCK(curproc); 280 error = racct_add(curproc, RACCT_SWAP, incr); 281 PROC_UNLOCK(curproc); 282 if (error != 0) 283 return (false); 284 } 285 #endif 286 287 pincr = atop(incr); 288 prev = atomic_fetchadd_long(&swap_reserved, pincr); 289 r = prev + pincr; 290 s = swap_total; 291 oc = atomic_load_int(&vm_overcommit); 292 if (r > s && (oc & SWAP_RESERVE_ALLOW_NONWIRED) != 0) { 293 s += vm_cnt.v_page_count - vm_cnt.v_free_reserved - 294 vm_wire_count(); 295 } 296 if ((oc & SWAP_RESERVE_FORCE_ON) != 0 && r > s && 297 priv_check(curthread, PRIV_VM_SWAP_NOQUOTA) != 0) { 298 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 299 KASSERT(prev >= pincr, 300 ("swap_reserved < incr on overcommit fail")); 301 goto out_error; 302 } 303 304 if (!swap_reserve_by_cred_rlimit(pincr, cred, oc)) { 305 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 306 KASSERT(prev >= pincr, 307 ("swap_reserved < incr on overcommit fail")); 308 goto out_error; 309 } 310 311 return (true); 312 313 out_error: 314 if (ppsratecheck(&lastfail, &curfail, 1)) { 315 printf("uid %d, pid %d: swap reservation " 316 "for %jd bytes failed\n", 317 cred->cr_ruidinfo->ui_uid, curproc->p_pid, incr); 318 } 319 #ifdef RACCT 320 if (RACCT_ENABLED()) { 321 PROC_LOCK(curproc); 322 racct_sub(curproc, RACCT_SWAP, incr); 323 PROC_UNLOCK(curproc); 324 } 325 #endif 326 327 return (false); 328 } 329 330 void 331 swap_reserve_force(vm_ooffset_t incr) 332 { 333 u_long pincr; 334 335 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", 336 __func__, (uintmax_t)incr)); 337 338 #ifdef RACCT 339 if (RACCT_ENABLED()) { 340 PROC_LOCK(curproc); 341 racct_add_force(curproc, RACCT_SWAP, incr); 342 PROC_UNLOCK(curproc); 343 } 344 #endif 345 pincr = atop(incr); 346 atomic_add_long(&swap_reserved, pincr); 347 swap_reserve_force_rlimit(pincr, curthread->td_ucred); 348 } 349 350 void 351 swap_release(vm_ooffset_t decr) 352 { 353 struct ucred *cred; 354 355 PROC_LOCK(curproc); 356 cred = curproc->p_ucred; 357 swap_release_by_cred(decr, cred); 358 PROC_UNLOCK(curproc); 359 } 360 361 void 362 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 363 { 364 u_long pdecr; 365 #ifdef INVARIANTS 366 u_long prev; 367 #endif 368 369 KASSERT((decr & PAGE_MASK) == 0, ("%s: decr: %ju & PAGE_MASK", 370 __func__, (uintmax_t)decr)); 371 372 pdecr = atop(decr); 373 #ifdef INVARIANTS 374 prev = atomic_fetchadd_long(&swap_reserved, -pdecr); 375 KASSERT(prev >= pdecr, ("swap_reserved < decr")); 376 #else 377 atomic_subtract_long(&swap_reserved, pdecr); 378 #endif 379 380 swap_release_by_cred_rlimit(pdecr, cred); 381 #ifdef RACCT 382 if (racct_enable) 383 racct_sub_cred(cred, RACCT_SWAP, decr); 384 #endif 385 } 386 387 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 388 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 389 static struct mtx swbuf_mtx; /* to sync nsw_wcount_async */ 390 static int nsw_wcount_async; /* limit async write buffers */ 391 static int nsw_wcount_async_max;/* assigned maximum */ 392 int nsw_cluster_max; /* maximum VOP I/O allowed */ 393 394 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 395 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 396 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 397 "Maximum running async swap ops"); 398 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS); 399 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD | 400 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A", 401 "Swap Fragmentation Info"); 402 403 static struct sx sw_alloc_sx; 404 405 /* 406 * "named" and "unnamed" anon region objects. Try to reduce the overhead 407 * of searching a named list by hashing it just a little. 408 */ 409 410 #define NOBJLISTS 8 411 412 #define NOBJLIST(handle) \ 413 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 414 415 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 416 static uma_zone_t swwbuf_zone; 417 static uma_zone_t swrbuf_zone; 418 static uma_zone_t swblk_zone; 419 static uma_zone_t swpctrie_zone; 420 421 /* 422 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 423 * calls hooked from other parts of the VM system and do not appear here. 424 * (see vm/swap_pager.h). 425 */ 426 static vm_object_t 427 swap_pager_alloc(void *handle, vm_ooffset_t size, 428 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 429 static void swap_pager_dealloc(vm_object_t object); 430 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, 431 int *); 432 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, 433 int *, pgo_getpages_iodone_t, void *); 434 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, int, int *); 435 static boolean_t 436 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 437 static void swap_pager_init(void); 438 static void swap_pager_unswapped(vm_page_t); 439 static void swap_pager_swapoff(struct swdevt *sp); 440 static void swap_pager_update_writecount(vm_object_t object, 441 vm_offset_t start, vm_offset_t end); 442 static void swap_pager_release_writecount(vm_object_t object, 443 vm_offset_t start, vm_offset_t end); 444 static void swap_pager_freespace_pgo(vm_object_t object, vm_pindex_t start, 445 vm_size_t size); 446 447 const struct pagerops swappagerops = { 448 .pgo_kvme_type = KVME_TYPE_SWAP, 449 .pgo_init = swap_pager_init, /* early system initialization of pager */ 450 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 451 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 452 .pgo_getpages = swap_pager_getpages, /* pagein */ 453 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 454 .pgo_putpages = swap_pager_putpages, /* pageout */ 455 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 456 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 457 .pgo_update_writecount = swap_pager_update_writecount, 458 .pgo_release_writecount = swap_pager_release_writecount, 459 .pgo_freespace = swap_pager_freespace_pgo, 460 }; 461 462 /* 463 * swap_*() routines are externally accessible. swp_*() routines are 464 * internal. 465 */ 466 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 467 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 468 469 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 470 "Maximum size of a swap block in pages"); 471 472 static void swp_sizecheck(void); 473 static void swp_pager_async_iodone(struct buf *bp); 474 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit); 475 static void swp_pager_free_empty_swblk(vm_object_t, struct swblk *sb); 476 static int swapongeom(struct vnode *); 477 static int swaponvp(struct thread *, struct vnode *, u_long); 478 static int swapoff_one(struct swdevt *sp, struct ucred *cred, 479 u_int flags); 480 481 /* 482 * Swap bitmap functions 483 */ 484 static void swp_pager_freeswapspace(const struct page_range *range); 485 static daddr_t swp_pager_getswapspace(int *npages); 486 487 /* 488 * Metadata functions 489 */ 490 static daddr_t swp_pager_meta_build(struct pctrie_iter *, vm_object_t object, 491 vm_pindex_t, daddr_t, bool); 492 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t, 493 vm_size_t *); 494 static void swp_pager_meta_transfer(vm_object_t src, vm_object_t dst, 495 vm_pindex_t pindex, vm_pindex_t count); 496 static void swp_pager_meta_free_all(vm_object_t); 497 static daddr_t swp_pager_meta_lookup(vm_object_t, vm_pindex_t); 498 499 static void 500 swp_pager_init_freerange(struct page_range *range) 501 { 502 range->start = SWAPBLK_NONE; 503 range->num = 0; 504 } 505 506 static void 507 swp_pager_update_freerange(struct page_range *range, daddr_t addr) 508 { 509 if (range->start + range->num == addr) { 510 range->num++; 511 } else { 512 swp_pager_freeswapspace(range); 513 range->start = addr; 514 range->num = 1; 515 } 516 } 517 518 static void * 519 swblk_trie_alloc(struct pctrie *ptree) 520 { 521 522 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? 523 M_USE_RESERVE : 0))); 524 } 525 526 static void 527 swblk_trie_free(struct pctrie *ptree, void *node) 528 { 529 530 uma_zfree(swpctrie_zone, node); 531 } 532 533 static int 534 swblk_start(struct swblk *sb, vm_pindex_t pindex) 535 { 536 return (sb == NULL || sb->p >= pindex ? 537 0 : pindex % SWAP_META_PAGES); 538 } 539 540 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); 541 542 static struct swblk * 543 swblk_lookup(vm_object_t object, vm_pindex_t pindex) 544 { 545 return (SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 546 rounddown(pindex, SWAP_META_PAGES))); 547 } 548 549 static void 550 swblk_lookup_remove(vm_object_t object, struct swblk *sb) 551 { 552 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 553 } 554 555 static bool 556 swblk_is_empty(vm_object_t object) 557 { 558 return (pctrie_is_empty(&object->un_pager.swp.swp_blks)); 559 } 560 561 static struct swblk * 562 swblk_iter_lookup_ge(struct pctrie_iter *blks, vm_pindex_t pindex) 563 { 564 return (SWAP_PCTRIE_ITER_LOOKUP_GE(blks, 565 rounddown(pindex, SWAP_META_PAGES))); 566 } 567 568 static void 569 swblk_iter_init_only(struct pctrie_iter *blks, vm_object_t object) 570 { 571 VM_OBJECT_ASSERT_LOCKED(object); 572 MPASS((object->flags & OBJ_SWAP) != 0); 573 pctrie_iter_init(blks, &object->un_pager.swp.swp_blks); 574 } 575 576 577 static struct swblk * 578 swblk_iter_init(struct pctrie_iter *blks, vm_object_t object, 579 vm_pindex_t pindex) 580 { 581 swblk_iter_init_only(blks, object); 582 return (swblk_iter_lookup_ge(blks, pindex)); 583 } 584 585 static struct swblk * 586 swblk_iter_reinit(struct pctrie_iter *blks, vm_object_t object, 587 vm_pindex_t pindex) 588 { 589 swblk_iter_init_only(blks, object); 590 return (SWAP_PCTRIE_ITER_LOOKUP(blks, 591 rounddown(pindex, SWAP_META_PAGES))); 592 } 593 594 static struct swblk * 595 swblk_iter_limit_init(struct pctrie_iter *blks, vm_object_t object, 596 vm_pindex_t pindex, vm_pindex_t limit) 597 { 598 VM_OBJECT_ASSERT_LOCKED(object); 599 MPASS((object->flags & OBJ_SWAP) != 0); 600 pctrie_iter_limit_init(blks, &object->un_pager.swp.swp_blks, limit); 601 return (swblk_iter_lookup_ge(blks, pindex)); 602 } 603 604 static struct swblk * 605 swblk_iter_next(struct pctrie_iter *blks) 606 { 607 return (SWAP_PCTRIE_ITER_JUMP_GE(blks, SWAP_META_PAGES)); 608 } 609 610 static struct swblk * 611 swblk_iter_lookup(struct pctrie_iter *blks, vm_pindex_t pindex) 612 { 613 return (SWAP_PCTRIE_ITER_LOOKUP(blks, 614 rounddown(pindex, SWAP_META_PAGES))); 615 } 616 617 static int 618 swblk_iter_insert(struct pctrie_iter *blks, struct swblk *sb) 619 { 620 return (SWAP_PCTRIE_ITER_INSERT(blks, sb)); 621 } 622 623 static void 624 swblk_iter_remove(struct pctrie_iter *blks) 625 { 626 SWAP_PCTRIE_ITER_REMOVE(blks); 627 } 628 629 /* 630 * SWP_SIZECHECK() - update swap_pager_full indication 631 * 632 * update the swap_pager_almost_full indication and warn when we are 633 * about to run out of swap space, using lowat/hiwat hysteresis. 634 * 635 * Clear swap_pager_full ( task killing ) indication when lowat is met. 636 * 637 * No restrictions on call 638 * This routine may not block. 639 */ 640 static void 641 swp_sizecheck(void) 642 { 643 644 if (swap_pager_avail < nswap_lowat) { 645 if (swap_pager_almost_full == 0) { 646 printf("swap_pager: out of swap space\n"); 647 swap_pager_almost_full = 1; 648 } 649 } else { 650 swap_pager_full = 0; 651 if (swap_pager_avail > nswap_hiwat) 652 swap_pager_almost_full = 0; 653 } 654 } 655 656 /* 657 * SWAP_PAGER_INIT() - initialize the swap pager! 658 * 659 * Expected to be started from system init. NOTE: This code is run 660 * before much else so be careful what you depend on. Most of the VM 661 * system has yet to be initialized at this point. 662 */ 663 static void 664 swap_pager_init(void) 665 { 666 /* 667 * Initialize object lists 668 */ 669 int i; 670 671 for (i = 0; i < NOBJLISTS; ++i) 672 TAILQ_INIT(&swap_pager_object_list[i]); 673 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 674 sx_init(&sw_alloc_sx, "swspsx"); 675 sx_init(&swdev_syscall_lock, "swsysc"); 676 677 /* 678 * The nsw_cluster_max is constrained by the bp->b_pages[] 679 * array, which has maxphys / PAGE_SIZE entries, and our locally 680 * defined MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 681 * constrained by the swap device interleave stripe size. 682 * 683 * Initialized early so that GEOM_ELI can see it. 684 */ 685 nsw_cluster_max = min(maxphys / PAGE_SIZE, MAX_PAGEOUT_CLUSTER); 686 } 687 688 /* 689 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 690 * 691 * Expected to be started from pageout process once, prior to entering 692 * its main loop. 693 */ 694 void 695 swap_pager_swap_init(void) 696 { 697 unsigned long n, n2; 698 699 /* 700 * Number of in-transit swap bp operations. Don't 701 * exhaust the pbufs completely. Make sure we 702 * initialize workable values (0 will work for hysteresis 703 * but it isn't very efficient). 704 * 705 * Currently we hardwire nsw_wcount_async to 4. This limit is 706 * designed to prevent other I/O from having high latencies due to 707 * our pageout I/O. The value 4 works well for one or two active swap 708 * devices but is probably a little low if you have more. Even so, 709 * a higher value would probably generate only a limited improvement 710 * with three or four active swap devices since the system does not 711 * typically have to pageout at extreme bandwidths. We will want 712 * at least 2 per swap devices, and 4 is a pretty good value if you 713 * have one NFS swap device due to the command/ack latency over NFS. 714 * So it all works out pretty well. 715 * 716 * nsw_cluster_max is initialized in swap_pager_init(). 717 */ 718 719 nsw_wcount_async = 4; 720 nsw_wcount_async_max = nsw_wcount_async; 721 mtx_init(&swbuf_mtx, "async swbuf mutex", NULL, MTX_DEF); 722 723 swwbuf_zone = pbuf_zsecond_create("swwbuf", nswbuf / 4); 724 swrbuf_zone = pbuf_zsecond_create("swrbuf", nswbuf / 2); 725 726 /* 727 * Initialize our zone, taking the user's requested size or 728 * estimating the number we need based on the number of pages 729 * in the system. 730 */ 731 n = maxswzone != 0 ? maxswzone / sizeof(struct swblk) : 732 vm_cnt.v_page_count / 2; 733 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, 734 pctrie_zone_init, NULL, UMA_ALIGN_PTR, 0); 735 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, 736 NULL, NULL, _Alignof(struct swblk) - 1, 0); 737 n2 = n; 738 do { 739 if (uma_zone_reserve_kva(swblk_zone, n)) 740 break; 741 /* 742 * if the allocation failed, try a zone two thirds the 743 * size of the previous attempt. 744 */ 745 n -= ((n + 2) / 3); 746 } while (n > 0); 747 748 /* 749 * Often uma_zone_reserve_kva() cannot reserve exactly the 750 * requested size. Account for the difference when 751 * calculating swap_maxpages. 752 */ 753 n = uma_zone_get_max(swblk_zone); 754 755 if (n < n2) 756 printf("Swap blk zone entries changed from %lu to %lu.\n", 757 n2, n); 758 /* absolute maximum we can handle assuming 100% efficiency */ 759 swap_maxpages = n * SWAP_META_PAGES; 760 swzone = n * sizeof(struct swblk); 761 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 762 printf("Cannot reserve swap pctrie zone, " 763 "reduce kern.maxswzone.\n"); 764 } 765 766 bool 767 swap_pager_init_object(vm_object_t object, void *handle, struct ucred *cred, 768 vm_ooffset_t size, vm_ooffset_t offset) 769 { 770 if (cred != NULL) { 771 if (!swap_reserve_by_cred(size, cred)) 772 return (false); 773 crhold(cred); 774 } 775 776 object->un_pager.swp.writemappings = 0; 777 object->handle = handle; 778 if (cred != NULL) { 779 object->cred = cred; 780 object->charge = size; 781 } 782 return (true); 783 } 784 785 static vm_object_t 786 swap_pager_alloc_init(objtype_t otype, void *handle, struct ucred *cred, 787 vm_ooffset_t size, vm_ooffset_t offset) 788 { 789 vm_object_t object; 790 791 /* 792 * The un_pager.swp.swp_blks trie is initialized by 793 * vm_object_allocate() to ensure the correct order of 794 * visibility to other threads. 795 */ 796 object = vm_object_allocate(otype, OFF_TO_IDX(offset + 797 PAGE_MASK + size)); 798 799 if (!swap_pager_init_object(object, handle, cred, size, offset)) { 800 vm_object_deallocate(object); 801 return (NULL); 802 } 803 return (object); 804 } 805 806 /* 807 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 808 * its metadata structures. 809 * 810 * This routine is called from the mmap and fork code to create a new 811 * OBJT_SWAP object. 812 * 813 * This routine must ensure that no live duplicate is created for 814 * the named object request, which is protected against by 815 * holding the sw_alloc_sx lock in case handle != NULL. 816 */ 817 static vm_object_t 818 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 819 vm_ooffset_t offset, struct ucred *cred) 820 { 821 vm_object_t object; 822 823 if (handle != NULL) { 824 /* 825 * Reference existing named region or allocate new one. There 826 * should not be a race here against swp_pager_meta_build() 827 * as called from vm_page_remove() in regards to the lookup 828 * of the handle. 829 */ 830 sx_xlock(&sw_alloc_sx); 831 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 832 if (object == NULL) { 833 object = swap_pager_alloc_init(OBJT_SWAP, handle, cred, 834 size, offset); 835 if (object != NULL) { 836 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 837 object, pager_object_list); 838 } 839 } 840 sx_xunlock(&sw_alloc_sx); 841 } else { 842 object = swap_pager_alloc_init(OBJT_SWAP, handle, cred, 843 size, offset); 844 } 845 return (object); 846 } 847 848 /* 849 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 850 * 851 * The swap backing for the object is destroyed. The code is 852 * designed such that we can reinstantiate it later, but this 853 * routine is typically called only when the entire object is 854 * about to be destroyed. 855 * 856 * The object must be locked. 857 */ 858 static void 859 swap_pager_dealloc(vm_object_t object) 860 { 861 862 VM_OBJECT_ASSERT_WLOCKED(object); 863 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 864 865 /* 866 * Remove from list right away so lookups will fail if we block for 867 * pageout completion. 868 */ 869 if ((object->flags & OBJ_ANON) == 0 && object->handle != NULL) { 870 VM_OBJECT_WUNLOCK(object); 871 sx_xlock(&sw_alloc_sx); 872 TAILQ_REMOVE(NOBJLIST(object->handle), object, 873 pager_object_list); 874 sx_xunlock(&sw_alloc_sx); 875 VM_OBJECT_WLOCK(object); 876 } 877 878 vm_object_pip_wait(object, "swpdea"); 879 880 /* 881 * Free all remaining metadata. We only bother to free it from 882 * the swap meta data. We do not attempt to free swapblk's still 883 * associated with vm_page_t's for this object. We do not care 884 * if paging is still in progress on some objects. 885 */ 886 swp_pager_meta_free_all(object); 887 object->handle = NULL; 888 object->type = OBJT_DEAD; 889 890 /* 891 * Release the allocation charge. 892 */ 893 if (object->cred != NULL) { 894 swap_release_by_cred(object->charge, object->cred); 895 object->charge = 0; 896 crfree(object->cred); 897 object->cred = NULL; 898 } 899 900 /* 901 * Hide the object from swap_pager_swapoff(). 902 */ 903 vm_object_clear_flag(object, OBJ_SWAP); 904 } 905 906 /************************************************************************ 907 * SWAP PAGER BITMAP ROUTINES * 908 ************************************************************************/ 909 910 /* 911 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 912 * 913 * Allocate swap for up to the requested number of pages. The 914 * starting swap block number (a page index) is returned or 915 * SWAPBLK_NONE if the allocation failed. 916 * 917 * Also has the side effect of advising that somebody made a mistake 918 * when they configured swap and didn't configure enough. 919 * 920 * This routine may not sleep. 921 * 922 * We allocate in round-robin fashion from the configured devices. 923 */ 924 static daddr_t 925 swp_pager_getswapspace(int *io_npages) 926 { 927 daddr_t blk; 928 struct swdevt *sp; 929 int mpages, npages; 930 931 KASSERT(*io_npages >= 1, 932 ("%s: npages not positive", __func__)); 933 blk = SWAPBLK_NONE; 934 mpages = *io_npages; 935 npages = imin(BLIST_MAX_ALLOC, mpages); 936 mtx_lock(&sw_dev_mtx); 937 sp = swdevhd; 938 while (!TAILQ_EMPTY(&swtailq)) { 939 if (sp == NULL) 940 sp = TAILQ_FIRST(&swtailq); 941 if ((sp->sw_flags & SW_CLOSING) == 0) 942 blk = blist_alloc(sp->sw_blist, &npages, mpages); 943 if (blk != SWAPBLK_NONE) 944 break; 945 sp = TAILQ_NEXT(sp, sw_list); 946 if (swdevhd == sp) { 947 if (npages == 1) 948 break; 949 mpages = npages - 1; 950 npages >>= 1; 951 } 952 } 953 if (blk != SWAPBLK_NONE) { 954 *io_npages = npages; 955 blk += sp->sw_first; 956 sp->sw_used += npages; 957 swap_pager_avail -= npages; 958 swp_sizecheck(); 959 swdevhd = TAILQ_NEXT(sp, sw_list); 960 } else { 961 if (swap_pager_full != 2) { 962 printf("swp_pager_getswapspace(%d): failed\n", 963 *io_npages); 964 swap_pager_full = 2; 965 swap_pager_almost_full = 1; 966 } 967 swdevhd = NULL; 968 } 969 mtx_unlock(&sw_dev_mtx); 970 return (blk); 971 } 972 973 static bool 974 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 975 { 976 977 return (blk >= sp->sw_first && blk < sp->sw_end); 978 } 979 980 static void 981 swp_pager_strategy(struct buf *bp) 982 { 983 struct swdevt *sp; 984 985 mtx_lock(&sw_dev_mtx); 986 TAILQ_FOREACH(sp, &swtailq, sw_list) { 987 if (swp_pager_isondev(bp->b_blkno, sp)) { 988 mtx_unlock(&sw_dev_mtx); 989 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 990 unmapped_buf_allowed) { 991 bp->b_data = unmapped_buf; 992 bp->b_offset = 0; 993 } else { 994 pmap_qenter((vm_offset_t)bp->b_data, 995 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 996 } 997 sp->sw_strategy(bp, sp); 998 return; 999 } 1000 } 1001 panic("Swapdev not found"); 1002 } 1003 1004 /* 1005 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 1006 * 1007 * This routine returns the specified swap blocks back to the bitmap. 1008 * 1009 * This routine may not sleep. 1010 */ 1011 static void 1012 swp_pager_freeswapspace(const struct page_range *range) 1013 { 1014 daddr_t blk, npages; 1015 struct swdevt *sp; 1016 1017 blk = range->start; 1018 npages = range->num; 1019 if (npages == 0) 1020 return; 1021 mtx_lock(&sw_dev_mtx); 1022 TAILQ_FOREACH(sp, &swtailq, sw_list) { 1023 if (swp_pager_isondev(blk, sp)) { 1024 sp->sw_used -= npages; 1025 /* 1026 * If we are attempting to stop swapping on 1027 * this device, we don't want to mark any 1028 * blocks free lest they be reused. 1029 */ 1030 if ((sp->sw_flags & SW_CLOSING) == 0) { 1031 blist_free(sp->sw_blist, blk - sp->sw_first, 1032 npages); 1033 swap_pager_avail += npages; 1034 swp_sizecheck(); 1035 } 1036 mtx_unlock(&sw_dev_mtx); 1037 return; 1038 } 1039 } 1040 panic("Swapdev not found"); 1041 } 1042 1043 /* 1044 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 1045 */ 1046 static int 1047 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 1048 { 1049 struct sbuf sbuf; 1050 struct swdevt *sp; 1051 const char *devname; 1052 int error; 1053 1054 error = sysctl_wire_old_buffer(req, 0); 1055 if (error != 0) 1056 return (error); 1057 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 1058 mtx_lock(&sw_dev_mtx); 1059 TAILQ_FOREACH(sp, &swtailq, sw_list) { 1060 if (vn_isdisk(sp->sw_vp)) 1061 devname = devtoname(sp->sw_vp->v_rdev); 1062 else 1063 devname = "[file]"; 1064 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 1065 blist_stats(sp->sw_blist, &sbuf); 1066 } 1067 mtx_unlock(&sw_dev_mtx); 1068 error = sbuf_finish(&sbuf); 1069 sbuf_delete(&sbuf); 1070 return (error); 1071 } 1072 1073 /* 1074 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 1075 * range within an object. 1076 * 1077 * This routine removes swapblk assignments from swap metadata. 1078 * 1079 * The external callers of this routine typically have already destroyed 1080 * or renamed vm_page_t's associated with this range in the object so 1081 * we should be ok. 1082 * 1083 * The object must be locked. 1084 */ 1085 void 1086 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size, 1087 vm_size_t *freed) 1088 { 1089 MPASS((object->flags & OBJ_SWAP) != 0); 1090 1091 swp_pager_meta_free(object, start, size, freed); 1092 } 1093 1094 static void 1095 swap_pager_freespace_pgo(vm_object_t object, vm_pindex_t start, vm_size_t size) 1096 { 1097 MPASS((object->flags & OBJ_SWAP) != 0); 1098 1099 swp_pager_meta_free(object, start, size, NULL); 1100 } 1101 1102 /* 1103 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 1104 * 1105 * Assigns swap blocks to the specified range within the object. The 1106 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 1107 * 1108 * Returns 0 on success, -1 on failure. 1109 */ 1110 int 1111 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_pindex_t size) 1112 { 1113 struct pctrie_iter blks; 1114 struct page_range range; 1115 daddr_t addr, blk; 1116 vm_pindex_t i, j; 1117 int n; 1118 1119 swp_pager_init_freerange(&range); 1120 VM_OBJECT_WLOCK(object); 1121 swblk_iter_init_only(&blks, object); 1122 for (i = 0; i < size; i += n) { 1123 n = MIN(size - i, INT_MAX); 1124 blk = swp_pager_getswapspace(&n); 1125 if (blk == SWAPBLK_NONE) { 1126 swp_pager_meta_free(object, start, i, NULL); 1127 VM_OBJECT_WUNLOCK(object); 1128 return (-1); 1129 } 1130 for (j = 0; j < n; ++j) { 1131 addr = swp_pager_meta_build(&blks, object, 1132 start + i + j, blk + j, false); 1133 if (addr != SWAPBLK_NONE) 1134 swp_pager_update_freerange(&range, addr); 1135 } 1136 } 1137 swp_pager_freeswapspace(&range); 1138 VM_OBJECT_WUNLOCK(object); 1139 return (0); 1140 } 1141 1142 /* 1143 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 1144 * and destroy the source. 1145 * 1146 * Copy any valid swapblks from the source to the destination. In 1147 * cases where both the source and destination have a valid swapblk, 1148 * we keep the destination's. 1149 * 1150 * This routine is allowed to sleep. It may sleep allocating metadata 1151 * indirectly through swp_pager_meta_build(). 1152 * 1153 * The source object contains no vm_page_t's (which is just as well) 1154 * 1155 * The source and destination objects must be locked. 1156 * Both object locks may temporarily be released. 1157 */ 1158 void 1159 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 1160 vm_pindex_t offset, int destroysource) 1161 { 1162 VM_OBJECT_ASSERT_WLOCKED(srcobject); 1163 VM_OBJECT_ASSERT_WLOCKED(dstobject); 1164 1165 /* 1166 * If destroysource is set, we remove the source object from the 1167 * swap_pager internal queue now. 1168 */ 1169 if (destroysource && (srcobject->flags & OBJ_ANON) == 0 && 1170 srcobject->handle != NULL) { 1171 VM_OBJECT_WUNLOCK(srcobject); 1172 VM_OBJECT_WUNLOCK(dstobject); 1173 sx_xlock(&sw_alloc_sx); 1174 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 1175 pager_object_list); 1176 sx_xunlock(&sw_alloc_sx); 1177 VM_OBJECT_WLOCK(dstobject); 1178 VM_OBJECT_WLOCK(srcobject); 1179 } 1180 1181 /* 1182 * Transfer source to destination. 1183 */ 1184 swp_pager_meta_transfer(srcobject, dstobject, offset, dstobject->size); 1185 1186 /* 1187 * Free left over swap blocks in source. 1188 */ 1189 if (destroysource) 1190 swp_pager_meta_free_all(srcobject); 1191 } 1192 1193 /* 1194 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1195 * the requested page. 1196 * 1197 * We determine whether good backing store exists for the requested 1198 * page and return TRUE if it does, FALSE if it doesn't. 1199 * 1200 * If TRUE, we also try to determine how much valid, contiguous backing 1201 * store exists before and after the requested page. 1202 */ 1203 static boolean_t 1204 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1205 int *after) 1206 { 1207 daddr_t blk, blk0; 1208 int i; 1209 1210 VM_OBJECT_ASSERT_LOCKED(object); 1211 KASSERT((object->flags & OBJ_SWAP) != 0, 1212 ("%s: object not swappable", __func__)); 1213 1214 /* 1215 * do we have good backing store at the requested index ? 1216 */ 1217 blk0 = swp_pager_meta_lookup(object, pindex); 1218 if (blk0 == SWAPBLK_NONE) { 1219 if (before) 1220 *before = 0; 1221 if (after) 1222 *after = 0; 1223 return (FALSE); 1224 } 1225 1226 /* 1227 * find backwards-looking contiguous good backing store 1228 */ 1229 if (before != NULL) { 1230 for (i = 1; i < SWB_NPAGES; i++) { 1231 if (i > pindex) 1232 break; 1233 blk = swp_pager_meta_lookup(object, pindex - i); 1234 if (blk != blk0 - i) 1235 break; 1236 } 1237 *before = i - 1; 1238 } 1239 1240 /* 1241 * find forward-looking contiguous good backing store 1242 */ 1243 if (after != NULL) { 1244 for (i = 1; i < SWB_NPAGES; i++) { 1245 blk = swp_pager_meta_lookup(object, pindex + i); 1246 if (blk != blk0 + i) 1247 break; 1248 } 1249 *after = i - 1; 1250 } 1251 return (TRUE); 1252 } 1253 1254 static void 1255 swap_pager_unswapped_acct(vm_page_t m) 1256 { 1257 KASSERT((m->object->flags & OBJ_SWAP) != 0, 1258 ("Free object not swappable")); 1259 if ((m->a.flags & PGA_SWAP_FREE) != 0) 1260 counter_u64_add(swap_free_completed, 1); 1261 vm_page_aflag_clear(m, PGA_SWAP_FREE | PGA_SWAP_SPACE); 1262 1263 /* 1264 * The meta data only exists if the object is OBJT_SWAP 1265 * and even then might not be allocated yet. 1266 */ 1267 } 1268 1269 /* 1270 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1271 * 1272 * This removes any associated swap backing store, whether valid or 1273 * not, from the page. 1274 * 1275 * This routine is typically called when a page is made dirty, at 1276 * which point any associated swap can be freed. MADV_FREE also 1277 * calls us in a special-case situation 1278 * 1279 * NOTE!!! If the page is clean and the swap was valid, the caller 1280 * should make the page dirty before calling this routine. This routine 1281 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1282 * depends on it. 1283 * 1284 * This routine may not sleep. 1285 * 1286 * The object containing the page may be locked. 1287 */ 1288 static void 1289 swap_pager_unswapped(vm_page_t m) 1290 { 1291 struct page_range range; 1292 struct swblk *sb; 1293 vm_object_t obj; 1294 1295 /* 1296 * Handle enqueing deferred frees first. If we do not have the 1297 * object lock we wait for the page daemon to clear the space. 1298 */ 1299 obj = m->object; 1300 if (!VM_OBJECT_WOWNED(obj)) { 1301 VM_PAGE_OBJECT_BUSY_ASSERT(m); 1302 /* 1303 * The caller is responsible for synchronization but we 1304 * will harmlessly handle races. This is typically provided 1305 * by only calling unswapped() when a page transitions from 1306 * clean to dirty. 1307 */ 1308 if ((m->a.flags & (PGA_SWAP_SPACE | PGA_SWAP_FREE)) == 1309 PGA_SWAP_SPACE) { 1310 vm_page_aflag_set(m, PGA_SWAP_FREE); 1311 counter_u64_add(swap_free_deferred, 1); 1312 } 1313 return; 1314 } 1315 swap_pager_unswapped_acct(m); 1316 1317 sb = swblk_lookup(m->object, m->pindex); 1318 if (sb == NULL) 1319 return; 1320 range.start = sb->d[m->pindex % SWAP_META_PAGES]; 1321 if (range.start == SWAPBLK_NONE) 1322 return; 1323 range.num = 1; 1324 swp_pager_freeswapspace(&range); 1325 sb->d[m->pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 1326 swp_pager_free_empty_swblk(m->object, sb); 1327 } 1328 1329 /* 1330 * swap_pager_getpages() - bring pages in from swap 1331 * 1332 * Attempt to page in the pages in array "ma" of length "count". The 1333 * caller may optionally specify that additional pages preceding and 1334 * succeeding the specified range be paged in. The number of such pages 1335 * is returned in the "rbehind" and "rahead" parameters, and they will 1336 * be in the inactive queue upon return. 1337 * 1338 * The pages in "ma" must be busied and will remain busied upon return. 1339 */ 1340 static int 1341 swap_pager_getpages_locked(vm_object_t object, vm_page_t *ma, int count, 1342 int *rbehind, int *rahead) 1343 { 1344 struct buf *bp; 1345 vm_page_t bm, mpred, msucc, p; 1346 vm_pindex_t pindex; 1347 daddr_t blk; 1348 int i, maxahead, maxbehind, reqcount; 1349 1350 VM_OBJECT_ASSERT_WLOCKED(object); 1351 reqcount = count; 1352 1353 KASSERT((object->flags & OBJ_SWAP) != 0, 1354 ("%s: object not swappable", __func__)); 1355 if (!swap_pager_haspage(object, ma[0]->pindex, &maxbehind, &maxahead)) { 1356 VM_OBJECT_WUNLOCK(object); 1357 return (VM_PAGER_FAIL); 1358 } 1359 1360 KASSERT(reqcount - 1 <= maxahead, 1361 ("page count %d extends beyond swap block", reqcount)); 1362 1363 /* 1364 * Do not transfer any pages other than those that are xbusied 1365 * when running during a split or collapse operation. This 1366 * prevents clustering from re-creating pages which are being 1367 * moved into another object. 1368 */ 1369 if ((object->flags & (OBJ_SPLIT | OBJ_DEAD)) != 0) { 1370 maxahead = reqcount - 1; 1371 maxbehind = 0; 1372 } 1373 1374 /* 1375 * Clip the readahead and readbehind ranges to exclude resident pages. 1376 */ 1377 if (rahead != NULL) { 1378 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1379 pindex = ma[reqcount - 1]->pindex; 1380 msucc = TAILQ_NEXT(ma[reqcount - 1], listq); 1381 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1382 *rahead = msucc->pindex - pindex - 1; 1383 } 1384 if (rbehind != NULL) { 1385 *rbehind = imin(*rbehind, maxbehind); 1386 pindex = ma[0]->pindex; 1387 mpred = TAILQ_PREV(ma[0], pglist, listq); 1388 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1389 *rbehind = pindex - mpred->pindex - 1; 1390 } 1391 1392 bm = ma[0]; 1393 for (i = 0; i < count; i++) 1394 ma[i]->oflags |= VPO_SWAPINPROG; 1395 1396 /* 1397 * Allocate readahead and readbehind pages. 1398 */ 1399 if (rbehind != NULL) { 1400 for (i = 1; i <= *rbehind; i++) { 1401 p = vm_page_alloc(object, ma[0]->pindex - i, 1402 VM_ALLOC_NORMAL); 1403 if (p == NULL) 1404 break; 1405 p->oflags |= VPO_SWAPINPROG; 1406 bm = p; 1407 } 1408 *rbehind = i - 1; 1409 } 1410 if (rahead != NULL) { 1411 for (i = 0; i < *rahead; i++) { 1412 p = vm_page_alloc(object, 1413 ma[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1414 if (p == NULL) 1415 break; 1416 p->oflags |= VPO_SWAPINPROG; 1417 } 1418 *rahead = i; 1419 } 1420 if (rbehind != NULL) 1421 count += *rbehind; 1422 if (rahead != NULL) 1423 count += *rahead; 1424 1425 vm_object_pip_add(object, count); 1426 1427 pindex = bm->pindex; 1428 blk = swp_pager_meta_lookup(object, pindex); 1429 KASSERT(blk != SWAPBLK_NONE, 1430 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1431 1432 VM_OBJECT_WUNLOCK(object); 1433 bp = uma_zalloc(swrbuf_zone, M_WAITOK); 1434 MPASS((bp->b_flags & B_MAXPHYS) != 0); 1435 /* Pages cannot leave the object while busy. */ 1436 for (i = 0, p = bm; i < count; i++, p = TAILQ_NEXT(p, listq)) { 1437 MPASS(p->pindex == bm->pindex + i); 1438 bp->b_pages[i] = p; 1439 } 1440 1441 bp->b_flags |= B_PAGING; 1442 bp->b_iocmd = BIO_READ; 1443 bp->b_iodone = swp_pager_async_iodone; 1444 bp->b_rcred = crhold(thread0.td_ucred); 1445 bp->b_wcred = crhold(thread0.td_ucred); 1446 bp->b_blkno = blk; 1447 bp->b_bcount = PAGE_SIZE * count; 1448 bp->b_bufsize = PAGE_SIZE * count; 1449 bp->b_npages = count; 1450 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1451 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1452 1453 VM_CNT_INC(v_swapin); 1454 VM_CNT_ADD(v_swappgsin, count); 1455 1456 /* 1457 * perform the I/O. NOTE!!! bp cannot be considered valid after 1458 * this point because we automatically release it on completion. 1459 * Instead, we look at the one page we are interested in which we 1460 * still hold a lock on even through the I/O completion. 1461 * 1462 * The other pages in our ma[] array are also released on completion, 1463 * so we cannot assume they are valid anymore either. 1464 * 1465 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1466 */ 1467 BUF_KERNPROC(bp); 1468 swp_pager_strategy(bp); 1469 1470 /* 1471 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1472 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1473 * is set in the metadata for each page in the request. 1474 */ 1475 VM_OBJECT_WLOCK(object); 1476 /* This could be implemented more efficiently with aflags */ 1477 while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) { 1478 ma[0]->oflags |= VPO_SWAPSLEEP; 1479 VM_CNT_INC(v_intrans); 1480 if (VM_OBJECT_SLEEP(object, &object->handle, PSWP, 1481 "swread", hz * 20)) { 1482 printf( 1483 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1484 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1485 } 1486 } 1487 VM_OBJECT_WUNLOCK(object); 1488 1489 /* 1490 * If we had an unrecoverable read error pages will not be valid. 1491 */ 1492 for (i = 0; i < reqcount; i++) 1493 if (ma[i]->valid != VM_PAGE_BITS_ALL) 1494 return (VM_PAGER_ERROR); 1495 1496 return (VM_PAGER_OK); 1497 1498 /* 1499 * A final note: in a low swap situation, we cannot deallocate swap 1500 * and mark a page dirty here because the caller is likely to mark 1501 * the page clean when we return, causing the page to possibly revert 1502 * to all-zero's later. 1503 */ 1504 } 1505 1506 static int 1507 swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count, 1508 int *rbehind, int *rahead) 1509 { 1510 1511 VM_OBJECT_WLOCK(object); 1512 return (swap_pager_getpages_locked(object, ma, count, rbehind, rahead)); 1513 } 1514 1515 /* 1516 * swap_pager_getpages_async(): 1517 * 1518 * Right now this is emulation of asynchronous operation on top of 1519 * swap_pager_getpages(). 1520 */ 1521 static int 1522 swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count, 1523 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1524 { 1525 int r, error; 1526 1527 r = swap_pager_getpages(object, ma, count, rbehind, rahead); 1528 switch (r) { 1529 case VM_PAGER_OK: 1530 error = 0; 1531 break; 1532 case VM_PAGER_ERROR: 1533 error = EIO; 1534 break; 1535 case VM_PAGER_FAIL: 1536 error = EINVAL; 1537 break; 1538 default: 1539 panic("unhandled swap_pager_getpages() error %d", r); 1540 } 1541 (iodone)(arg, ma, count, error); 1542 1543 return (r); 1544 } 1545 1546 /* 1547 * swap_pager_putpages: 1548 * 1549 * Assign swap (if necessary) and initiate I/O on the specified pages. 1550 * 1551 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1552 * vm_page reservation system coupled with properly written VFS devices 1553 * should ensure that no low-memory deadlock occurs. This is an area 1554 * which needs work. 1555 * 1556 * The parent has N vm_object_pip_add() references prior to 1557 * calling us and will remove references for rtvals[] that are 1558 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1559 * completion. 1560 * 1561 * The parent has soft-busy'd the pages it passes us and will unbusy 1562 * those whose rtvals[] entry is not set to VM_PAGER_PEND on return. 1563 * We need to unbusy the rest on I/O completion. 1564 */ 1565 static void 1566 swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count, 1567 int flags, int *rtvals) 1568 { 1569 struct pctrie_iter blks; 1570 struct page_range range; 1571 struct buf *bp; 1572 daddr_t addr, blk; 1573 vm_page_t mreq; 1574 int i, j, n; 1575 bool async; 1576 1577 KASSERT(count == 0 || ma[0]->object == object, 1578 ("%s: object mismatch %p/%p", 1579 __func__, object, ma[0]->object)); 1580 1581 VM_OBJECT_WUNLOCK(object); 1582 async = curproc == pageproc && (flags & VM_PAGER_PUT_SYNC) == 0; 1583 swp_pager_init_freerange(&range); 1584 1585 /* 1586 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1587 * The page is left dirty until the pageout operation completes 1588 * successfully. 1589 */ 1590 for (i = 0; i < count; i += n) { 1591 /* Maximum I/O size is limited by maximum swap block size. */ 1592 n = min(count - i, nsw_cluster_max); 1593 1594 if (async) { 1595 mtx_lock(&swbuf_mtx); 1596 while (nsw_wcount_async == 0) 1597 msleep(&nsw_wcount_async, &swbuf_mtx, PVM, 1598 "swbufa", 0); 1599 nsw_wcount_async--; 1600 mtx_unlock(&swbuf_mtx); 1601 } 1602 1603 /* Get a block of swap of size up to size n. */ 1604 blk = swp_pager_getswapspace(&n); 1605 if (blk == SWAPBLK_NONE) { 1606 mtx_lock(&swbuf_mtx); 1607 if (++nsw_wcount_async == 1) 1608 wakeup(&nsw_wcount_async); 1609 mtx_unlock(&swbuf_mtx); 1610 for (j = 0; j < n; ++j) 1611 rtvals[i + j] = VM_PAGER_FAIL; 1612 continue; 1613 } 1614 VM_OBJECT_WLOCK(object); 1615 swblk_iter_init_only(&blks, object); 1616 for (j = 0; j < n; ++j) { 1617 mreq = ma[i + j]; 1618 vm_page_aflag_clear(mreq, PGA_SWAP_FREE); 1619 KASSERT(mreq->object == object, 1620 ("%s: object mismatch %p/%p", 1621 __func__, mreq->object, object)); 1622 addr = swp_pager_meta_build(&blks, object, 1623 mreq->pindex, blk + j, false); 1624 if (addr != SWAPBLK_NONE) 1625 swp_pager_update_freerange(&range, addr); 1626 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1627 mreq->oflags |= VPO_SWAPINPROG; 1628 } 1629 VM_OBJECT_WUNLOCK(object); 1630 1631 bp = uma_zalloc(swwbuf_zone, M_WAITOK); 1632 MPASS((bp->b_flags & B_MAXPHYS) != 0); 1633 if (async) 1634 bp->b_flags |= B_ASYNC; 1635 bp->b_flags |= B_PAGING; 1636 bp->b_iocmd = BIO_WRITE; 1637 1638 bp->b_rcred = crhold(thread0.td_ucred); 1639 bp->b_wcred = crhold(thread0.td_ucred); 1640 bp->b_bcount = PAGE_SIZE * n; 1641 bp->b_bufsize = PAGE_SIZE * n; 1642 bp->b_blkno = blk; 1643 for (j = 0; j < n; j++) 1644 bp->b_pages[j] = ma[i + j]; 1645 bp->b_npages = n; 1646 1647 /* 1648 * Must set dirty range for NFS to work. 1649 */ 1650 bp->b_dirtyoff = 0; 1651 bp->b_dirtyend = bp->b_bcount; 1652 1653 VM_CNT_INC(v_swapout); 1654 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1655 1656 /* 1657 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1658 * can call the async completion routine at the end of a 1659 * synchronous I/O operation. Otherwise, our caller would 1660 * perform duplicate unbusy and wakeup operations on the page 1661 * and object, respectively. 1662 */ 1663 for (j = 0; j < n; j++) 1664 rtvals[i + j] = VM_PAGER_PEND; 1665 1666 /* 1667 * asynchronous 1668 * 1669 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1670 */ 1671 if (async) { 1672 bp->b_iodone = swp_pager_async_iodone; 1673 BUF_KERNPROC(bp); 1674 swp_pager_strategy(bp); 1675 continue; 1676 } 1677 1678 /* 1679 * synchronous 1680 * 1681 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1682 */ 1683 bp->b_iodone = bdone; 1684 swp_pager_strategy(bp); 1685 1686 /* 1687 * Wait for the sync I/O to complete. 1688 */ 1689 bwait(bp, PVM, "swwrt"); 1690 1691 /* 1692 * Now that we are through with the bp, we can call the 1693 * normal async completion, which frees everything up. 1694 */ 1695 swp_pager_async_iodone(bp); 1696 } 1697 swp_pager_freeswapspace(&range); 1698 VM_OBJECT_WLOCK(object); 1699 } 1700 1701 /* 1702 * swp_pager_async_iodone: 1703 * 1704 * Completion routine for asynchronous reads and writes from/to swap. 1705 * Also called manually by synchronous code to finish up a bp. 1706 * 1707 * This routine may not sleep. 1708 */ 1709 static void 1710 swp_pager_async_iodone(struct buf *bp) 1711 { 1712 int i; 1713 vm_object_t object = NULL; 1714 1715 /* 1716 * Report error - unless we ran out of memory, in which case 1717 * we've already logged it in swapgeom_strategy(). 1718 */ 1719 if (bp->b_ioflags & BIO_ERROR && bp->b_error != ENOMEM) { 1720 printf( 1721 "swap_pager: I/O error - %s failed; blkno %ld," 1722 "size %ld, error %d\n", 1723 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1724 (long)bp->b_blkno, 1725 (long)bp->b_bcount, 1726 bp->b_error 1727 ); 1728 } 1729 1730 /* 1731 * remove the mapping for kernel virtual 1732 */ 1733 if (buf_mapped(bp)) 1734 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1735 else 1736 bp->b_data = bp->b_kvabase; 1737 1738 if (bp->b_npages) { 1739 object = bp->b_pages[0]->object; 1740 VM_OBJECT_WLOCK(object); 1741 } 1742 1743 /* 1744 * cleanup pages. If an error occurs writing to swap, we are in 1745 * very serious trouble. If it happens to be a disk error, though, 1746 * we may be able to recover by reassigning the swap later on. So 1747 * in this case we remove the m->swapblk assignment for the page 1748 * but do not free it in the rlist. The errornous block(s) are thus 1749 * never reallocated as swap. Redirty the page and continue. 1750 */ 1751 for (i = 0; i < bp->b_npages; ++i) { 1752 vm_page_t m = bp->b_pages[i]; 1753 1754 m->oflags &= ~VPO_SWAPINPROG; 1755 if (m->oflags & VPO_SWAPSLEEP) { 1756 m->oflags &= ~VPO_SWAPSLEEP; 1757 wakeup(&object->handle); 1758 } 1759 1760 /* We always have space after I/O, successful or not. */ 1761 vm_page_aflag_set(m, PGA_SWAP_SPACE); 1762 1763 if (bp->b_ioflags & BIO_ERROR) { 1764 /* 1765 * If an error occurs I'd love to throw the swapblk 1766 * away without freeing it back to swapspace, so it 1767 * can never be used again. But I can't from an 1768 * interrupt. 1769 */ 1770 if (bp->b_iocmd == BIO_READ) { 1771 /* 1772 * NOTE: for reads, m->dirty will probably 1773 * be overridden by the original caller of 1774 * getpages so don't play cute tricks here. 1775 */ 1776 vm_page_invalid(m); 1777 if (i < bp->b_pgbefore || 1778 i >= bp->b_npages - bp->b_pgafter) 1779 vm_page_free_invalid(m); 1780 } else { 1781 /* 1782 * If a write error occurs, reactivate page 1783 * so it doesn't clog the inactive list, 1784 * then finish the I/O. 1785 */ 1786 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1787 1788 /* PQ_UNSWAPPABLE? */ 1789 vm_page_activate(m); 1790 vm_page_sunbusy(m); 1791 } 1792 } else if (bp->b_iocmd == BIO_READ) { 1793 /* 1794 * NOTE: for reads, m->dirty will probably be 1795 * overridden by the original caller of getpages so 1796 * we cannot set them in order to free the underlying 1797 * swap in a low-swap situation. I don't think we'd 1798 * want to do that anyway, but it was an optimization 1799 * that existed in the old swapper for a time before 1800 * it got ripped out due to precisely this problem. 1801 */ 1802 KASSERT(!pmap_page_is_mapped(m), 1803 ("swp_pager_async_iodone: page %p is mapped", m)); 1804 KASSERT(m->dirty == 0, 1805 ("swp_pager_async_iodone: page %p is dirty", m)); 1806 1807 vm_page_valid(m); 1808 if (i < bp->b_pgbefore || 1809 i >= bp->b_npages - bp->b_pgafter) 1810 vm_page_readahead_finish(m); 1811 } else { 1812 /* 1813 * For write success, clear the dirty 1814 * status, then finish the I/O ( which decrements the 1815 * busy count and possibly wakes waiter's up ). 1816 * A page is only written to swap after a period of 1817 * inactivity. Therefore, we do not expect it to be 1818 * reused. 1819 */ 1820 KASSERT(!pmap_page_is_write_mapped(m), 1821 ("swp_pager_async_iodone: page %p is not write" 1822 " protected", m)); 1823 vm_page_undirty(m); 1824 vm_page_deactivate_noreuse(m); 1825 vm_page_sunbusy(m); 1826 } 1827 } 1828 1829 /* 1830 * adjust pip. NOTE: the original parent may still have its own 1831 * pip refs on the object. 1832 */ 1833 if (object != NULL) { 1834 vm_object_pip_wakeupn(object, bp->b_npages); 1835 VM_OBJECT_WUNLOCK(object); 1836 } 1837 1838 /* 1839 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1840 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1841 * trigger a KASSERT in relpbuf(). 1842 */ 1843 if (bp->b_vp) { 1844 bp->b_vp = NULL; 1845 bp->b_bufobj = NULL; 1846 } 1847 /* 1848 * release the physical I/O buffer 1849 */ 1850 if (bp->b_flags & B_ASYNC) { 1851 mtx_lock(&swbuf_mtx); 1852 if (++nsw_wcount_async == 1) 1853 wakeup(&nsw_wcount_async); 1854 mtx_unlock(&swbuf_mtx); 1855 } 1856 uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp); 1857 } 1858 1859 int 1860 swap_pager_nswapdev(void) 1861 { 1862 1863 return (nswapdev); 1864 } 1865 1866 static void 1867 swp_pager_force_dirty(struct page_range *range, vm_page_t m, daddr_t *blk) 1868 { 1869 vm_page_dirty(m); 1870 swap_pager_unswapped_acct(m); 1871 swp_pager_update_freerange(range, *blk); 1872 *blk = SWAPBLK_NONE; 1873 vm_page_launder(m); 1874 } 1875 1876 u_long 1877 swap_pager_swapped_pages(vm_object_t object) 1878 { 1879 struct pctrie_iter blks; 1880 struct swblk *sb; 1881 u_long res; 1882 int i; 1883 1884 VM_OBJECT_ASSERT_LOCKED(object); 1885 1886 if (swblk_is_empty(object)) 1887 return (0); 1888 1889 res = 0; 1890 for (sb = swblk_iter_init(&blks, object, 0); sb != NULL; 1891 sb = swblk_iter_next(&blks)) { 1892 for (i = 0; i < SWAP_META_PAGES; i++) { 1893 if (sb->d[i] != SWAPBLK_NONE) 1894 res++; 1895 } 1896 } 1897 return (res); 1898 } 1899 1900 /* 1901 * swap_pager_swapoff_object: 1902 * 1903 * Page in all of the pages that have been paged out for an object 1904 * to a swap device. 1905 */ 1906 static void 1907 swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object) 1908 { 1909 struct pctrie_iter blks, pages; 1910 struct page_range range; 1911 struct swblk *sb; 1912 vm_page_t m; 1913 int i, rahead, rv; 1914 bool sb_empty; 1915 1916 VM_OBJECT_ASSERT_WLOCKED(object); 1917 KASSERT((object->flags & OBJ_SWAP) != 0, 1918 ("%s: Object not swappable", __func__)); 1919 KASSERT((object->flags & OBJ_DEAD) == 0, 1920 ("%s: Object already dead", __func__)); 1921 KASSERT((sp->sw_flags & SW_CLOSING) != 0, 1922 ("%s: Device not blocking further allocations", __func__)); 1923 1924 vm_page_iter_init(&pages, object); 1925 swp_pager_init_freerange(&range); 1926 sb = swblk_iter_init(&blks, object, 0); 1927 while (sb != NULL) { 1928 sb_empty = true; 1929 for (i = 0; i < SWAP_META_PAGES; i++) { 1930 /* Skip an invalid block. */ 1931 if (sb->d[i] == SWAPBLK_NONE) 1932 continue; 1933 /* Skip a block not of this device. */ 1934 if (!swp_pager_isondev(sb->d[i], sp)) { 1935 sb_empty = false; 1936 continue; 1937 } 1938 1939 /* 1940 * Look for a page corresponding to this block. If the 1941 * found page has pending operations, sleep and restart 1942 * the scan. 1943 */ 1944 m = vm_page_iter_lookup(&pages, blks.index + i); 1945 if (m != NULL && (m->oflags & VPO_SWAPINPROG) != 0) { 1946 m->oflags |= VPO_SWAPSLEEP; 1947 VM_OBJECT_SLEEP(object, &object->handle, PSWP, 1948 "swpoff", 0); 1949 break; 1950 } 1951 1952 /* 1953 * If the found page is valid, mark it dirty and free 1954 * the swap block. 1955 */ 1956 if (m != NULL && vm_page_all_valid(m)) { 1957 swp_pager_force_dirty(&range, m, &sb->d[i]); 1958 continue; 1959 } 1960 /* Is there a page we can acquire or allocate? */ 1961 if (m != NULL) { 1962 if (!vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL)) 1963 break; 1964 } else if ((m = vm_page_alloc(object, blks.index + i, 1965 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL)) == NULL) 1966 break; 1967 1968 /* Get the page from swap, and restart the scan. */ 1969 vm_object_pip_add(object, 1); 1970 rahead = SWAP_META_PAGES; 1971 rv = swap_pager_getpages_locked(object, &m, 1, 1972 NULL, &rahead); 1973 if (rv != VM_PAGER_OK) 1974 panic("%s: read from swap failed: %d", 1975 __func__, rv); 1976 VM_OBJECT_WLOCK(object); 1977 vm_object_pip_wakeupn(object, 1); 1978 KASSERT(vm_page_all_valid(m), 1979 ("%s: Page %p not all valid", __func__, m)); 1980 vm_page_xunbusy(m); 1981 break; 1982 } 1983 if (i < SWAP_META_PAGES) { 1984 /* 1985 * The object lock has been released and regained. 1986 * Perhaps the object is now dead. 1987 */ 1988 if ((object->flags & OBJ_DEAD) != 0) { 1989 /* 1990 * Make sure that pending writes finish before 1991 * returning. 1992 */ 1993 vm_object_pip_wait(object, "swpoff"); 1994 swp_pager_meta_free_all(object); 1995 break; 1996 } 1997 1998 /* 1999 * The swapblk could have been freed, so reset the pages 2000 * iterator and search again for the first swblk at or 2001 * after blks.index. 2002 */ 2003 pctrie_iter_reset(&pages); 2004 sb = swblk_iter_init(&blks, object, blks.index); 2005 continue; 2006 } 2007 if (sb_empty) { 2008 swblk_iter_remove(&blks); 2009 uma_zfree(swblk_zone, sb); 2010 } 2011 2012 /* 2013 * It is safe to advance to the next block. No allocations 2014 * before blk.index have happened, even with the lock released, 2015 * because allocations on this device are blocked. 2016 */ 2017 sb = swblk_iter_next(&blks); 2018 } 2019 swp_pager_freeswapspace(&range); 2020 } 2021 2022 /* 2023 * swap_pager_swapoff: 2024 * 2025 * Page in all of the pages that have been paged out to the 2026 * given device. The corresponding blocks in the bitmap must be 2027 * marked as allocated and the device must be flagged SW_CLOSING. 2028 * There may be no processes swapped out to the device. 2029 * 2030 * This routine may block. 2031 */ 2032 static void 2033 swap_pager_swapoff(struct swdevt *sp) 2034 { 2035 vm_object_t object; 2036 int retries; 2037 2038 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2039 2040 retries = 0; 2041 full_rescan: 2042 mtx_lock(&vm_object_list_mtx); 2043 TAILQ_FOREACH(object, &vm_object_list, object_list) { 2044 if ((object->flags & OBJ_SWAP) == 0) 2045 continue; 2046 mtx_unlock(&vm_object_list_mtx); 2047 /* Depends on type-stability. */ 2048 VM_OBJECT_WLOCK(object); 2049 2050 /* 2051 * Dead objects are eventually terminated on their own. 2052 */ 2053 if ((object->flags & OBJ_DEAD) != 0) 2054 goto next_obj; 2055 2056 /* 2057 * Sync with fences placed after pctrie 2058 * initialization. We must not access pctrie below 2059 * unless we checked that our object is swap and not 2060 * dead. 2061 */ 2062 atomic_thread_fence_acq(); 2063 if ((object->flags & OBJ_SWAP) == 0) 2064 goto next_obj; 2065 2066 swap_pager_swapoff_object(sp, object); 2067 next_obj: 2068 VM_OBJECT_WUNLOCK(object); 2069 mtx_lock(&vm_object_list_mtx); 2070 } 2071 mtx_unlock(&vm_object_list_mtx); 2072 2073 if (sp->sw_used) { 2074 /* 2075 * Objects may be locked or paging to the device being 2076 * removed, so we will miss their pages and need to 2077 * make another pass. We have marked this device as 2078 * SW_CLOSING, so the activity should finish soon. 2079 */ 2080 retries++; 2081 if (retries > 100) { 2082 panic("swapoff: failed to locate %d swap blocks", 2083 sp->sw_used); 2084 } 2085 pause("swpoff", hz / 20); 2086 goto full_rescan; 2087 } 2088 EVENTHANDLER_INVOKE(swapoff, sp); 2089 } 2090 2091 /************************************************************************ 2092 * SWAP META DATA * 2093 ************************************************************************ 2094 * 2095 * These routines manipulate the swap metadata stored in the 2096 * OBJT_SWAP object. 2097 * 2098 * Swap metadata is implemented with a global hash and not directly 2099 * linked into the object. Instead the object simply contains 2100 * appropriate tracking counters. 2101 */ 2102 2103 /* 2104 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? 2105 */ 2106 static bool 2107 swp_pager_swblk_empty(struct swblk *sb, int start, int limit) 2108 { 2109 int i; 2110 2111 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); 2112 for (i = start; i < limit; i++) { 2113 if (sb->d[i] != SWAPBLK_NONE) 2114 return (false); 2115 } 2116 return (true); 2117 } 2118 2119 /* 2120 * SWP_PAGER_FREE_EMPTY_SWBLK() - frees if a block is free 2121 * 2122 * Nothing is done if the block is still in use. 2123 */ 2124 static void 2125 swp_pager_free_empty_swblk(vm_object_t object, struct swblk *sb) 2126 { 2127 2128 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 2129 swblk_lookup_remove(object, sb); 2130 uma_zfree(swblk_zone, sb); 2131 } 2132 } 2133 2134 /* 2135 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 2136 * 2137 * Try to add the specified swapblk to the object's swap metadata. If 2138 * nowait_noreplace is set, add the specified swapblk only if there is no 2139 * previously assigned swapblk at pindex. If the swapblk is invalid, and 2140 * replaces a valid swapblk, empty swap metadata is freed. If memory 2141 * allocation fails, and nowait_noreplace is set, return the specified 2142 * swapblk immediately to indicate failure; otherwise, wait and retry until 2143 * memory allocation succeeds. Return the previously assigned swapblk, if 2144 * any. 2145 */ 2146 static daddr_t 2147 swp_pager_meta_build(struct pctrie_iter *blks, vm_object_t object, 2148 vm_pindex_t pindex, daddr_t swapblk, bool nowait_noreplace) 2149 { 2150 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 2151 struct swblk *sb, *sb1; 2152 vm_pindex_t modpi; 2153 daddr_t prev_swapblk; 2154 int error, i; 2155 2156 VM_OBJECT_ASSERT_WLOCKED(object); 2157 2158 sb = swblk_iter_lookup(blks, pindex); 2159 if (sb == NULL) { 2160 if (swapblk == SWAPBLK_NONE) 2161 return (SWAPBLK_NONE); 2162 for (;;) { 2163 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 2164 pageproc ? M_USE_RESERVE : 0)); 2165 if (sb != NULL) { 2166 sb->p = rounddown(pindex, SWAP_META_PAGES); 2167 for (i = 0; i < SWAP_META_PAGES; i++) 2168 sb->d[i] = SWAPBLK_NONE; 2169 if (atomic_cmpset_int(&swblk_zone_exhausted, 2170 1, 0)) 2171 printf("swblk zone ok\n"); 2172 break; 2173 } 2174 if (nowait_noreplace) 2175 return (swapblk); 2176 VM_OBJECT_WUNLOCK(object); 2177 if (uma_zone_exhausted(swblk_zone)) { 2178 if (atomic_cmpset_int(&swblk_zone_exhausted, 2179 0, 1)) 2180 printf("swap blk zone exhausted, " 2181 "increase kern.maxswzone\n"); 2182 vm_pageout_oom(VM_OOM_SWAPZ); 2183 pause("swzonxb", 10); 2184 } else 2185 uma_zwait(swblk_zone); 2186 VM_OBJECT_WLOCK(object); 2187 sb = swblk_iter_reinit(blks, object, pindex); 2188 if (sb != NULL) 2189 /* 2190 * Somebody swapped out a nearby page, 2191 * allocating swblk at the pindex index, 2192 * while we dropped the object lock. 2193 */ 2194 goto allocated; 2195 } 2196 for (;;) { 2197 error = swblk_iter_insert(blks, sb); 2198 if (error == 0) { 2199 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2200 1, 0)) 2201 printf("swpctrie zone ok\n"); 2202 break; 2203 } 2204 if (nowait_noreplace) { 2205 uma_zfree(swblk_zone, sb); 2206 return (swapblk); 2207 } 2208 VM_OBJECT_WUNLOCK(object); 2209 if (uma_zone_exhausted(swpctrie_zone)) { 2210 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2211 0, 1)) 2212 printf("swap pctrie zone exhausted, " 2213 "increase kern.maxswzone\n"); 2214 vm_pageout_oom(VM_OOM_SWAPZ); 2215 pause("swzonxp", 10); 2216 } else 2217 uma_zwait(swpctrie_zone); 2218 VM_OBJECT_WLOCK(object); 2219 sb1 = swblk_iter_reinit(blks, object, pindex); 2220 if (sb1 != NULL) { 2221 uma_zfree(swblk_zone, sb); 2222 sb = sb1; 2223 goto allocated; 2224 } 2225 } 2226 } 2227 allocated: 2228 MPASS(sb->p == rounddown(pindex, SWAP_META_PAGES)); 2229 2230 modpi = pindex % SWAP_META_PAGES; 2231 /* Return prior contents of metadata. */ 2232 prev_swapblk = sb->d[modpi]; 2233 if (!nowait_noreplace || prev_swapblk == SWAPBLK_NONE) { 2234 /* Enter block into metadata. */ 2235 sb->d[modpi] = swapblk; 2236 2237 /* 2238 * Free the swblk if we end up with the empty page run. 2239 */ 2240 if (swapblk == SWAPBLK_NONE && 2241 swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 2242 swblk_iter_remove(blks); 2243 uma_zfree(swblk_zone, sb); 2244 } 2245 } 2246 return (prev_swapblk); 2247 } 2248 2249 /* 2250 * SWP_PAGER_META_TRANSFER() - transfer a range of blocks in the srcobject's 2251 * swap metadata into dstobject. 2252 * 2253 * Blocks in src that correspond to holes in dst are transferred. Blocks 2254 * in src that correspond to blocks in dst are freed. 2255 */ 2256 static void 2257 swp_pager_meta_transfer(vm_object_t srcobject, vm_object_t dstobject, 2258 vm_pindex_t pindex, vm_pindex_t count) 2259 { 2260 struct pctrie_iter dstblks, srcblks; 2261 struct page_range range; 2262 struct swblk *sb; 2263 daddr_t blk, d[SWAP_META_PAGES]; 2264 vm_pindex_t last; 2265 int d_mask, i, limit, start; 2266 _Static_assert(8 * sizeof(d_mask) >= SWAP_META_PAGES, 2267 "d_mask not big enough"); 2268 2269 VM_OBJECT_ASSERT_WLOCKED(srcobject); 2270 VM_OBJECT_ASSERT_WLOCKED(dstobject); 2271 2272 if (count == 0 || swblk_is_empty(srcobject)) 2273 return; 2274 2275 swp_pager_init_freerange(&range); 2276 d_mask = 0; 2277 last = pindex + count; 2278 swblk_iter_init_only(&dstblks, dstobject); 2279 for (sb = swblk_iter_limit_init(&srcblks, srcobject, pindex, last), 2280 start = swblk_start(sb, pindex); 2281 sb != NULL; sb = swblk_iter_next(&srcblks), start = 0) { 2282 limit = MIN(last - srcblks.index, SWAP_META_PAGES); 2283 for (i = start; i < limit; i++) { 2284 if (sb->d[i] == SWAPBLK_NONE) 2285 continue; 2286 blk = swp_pager_meta_build(&dstblks, dstobject, 2287 srcblks.index + i - pindex, sb->d[i], true); 2288 if (blk == sb->d[i]) { 2289 /* 2290 * Failed memory allocation stopped transfer; 2291 * save this block for transfer with lock 2292 * released. 2293 */ 2294 d[i] = blk; 2295 d_mask |= 1 << i; 2296 } else if (blk != SWAPBLK_NONE) { 2297 /* Dst has a block at pindex, so free block. */ 2298 swp_pager_update_freerange(&range, sb->d[i]); 2299 } 2300 sb->d[i] = SWAPBLK_NONE; 2301 } 2302 if (swp_pager_swblk_empty(sb, 0, start) && 2303 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2304 swblk_iter_remove(&srcblks); 2305 uma_zfree(swblk_zone, sb); 2306 } 2307 if (d_mask != 0) { 2308 /* Finish block transfer, with the lock released. */ 2309 VM_OBJECT_WUNLOCK(srcobject); 2310 do { 2311 i = ffs(d_mask) - 1; 2312 swp_pager_meta_build(&dstblks, dstobject, 2313 srcblks.index + i - pindex, d[i], false); 2314 d_mask &= ~(1 << i); 2315 } while (d_mask != 0); 2316 VM_OBJECT_WLOCK(srcobject); 2317 2318 /* 2319 * While the lock was not held, the iterator path could 2320 * have become stale, so discard it. 2321 */ 2322 pctrie_iter_reset(&srcblks); 2323 } 2324 } 2325 swp_pager_freeswapspace(&range); 2326 } 2327 2328 /* 2329 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2330 * 2331 * Return freed swap blocks to the swap bitmap, and free emptied swblk 2332 * metadata. With 'freed' set, provide a count of freed blocks that were 2333 * not associated with valid resident pages. 2334 */ 2335 static void 2336 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count, 2337 vm_size_t *freed) 2338 { 2339 struct pctrie_iter blks, pages; 2340 struct page_range range; 2341 struct swblk *sb; 2342 vm_page_t m; 2343 vm_pindex_t last; 2344 vm_size_t fc; 2345 int i, limit, start; 2346 2347 VM_OBJECT_ASSERT_WLOCKED(object); 2348 2349 fc = 0; 2350 if (count == 0 || swblk_is_empty(object)) 2351 goto out; 2352 2353 swp_pager_init_freerange(&range); 2354 vm_page_iter_init(&pages, object); 2355 last = pindex + count; 2356 for (sb = swblk_iter_limit_init(&blks, object, pindex, last), 2357 start = swblk_start(sb, pindex); 2358 sb != NULL; sb = swblk_iter_next(&blks), start = 0) { 2359 limit = MIN(last - blks.index, SWAP_META_PAGES); 2360 for (i = start; i < limit; i++) { 2361 if (sb->d[i] == SWAPBLK_NONE) 2362 continue; 2363 swp_pager_update_freerange(&range, sb->d[i]); 2364 if (freed != NULL) { 2365 m = vm_page_iter_lookup(&pages, blks.index + i); 2366 if (m == NULL || vm_page_none_valid(m)) 2367 fc++; 2368 } 2369 sb->d[i] = SWAPBLK_NONE; 2370 } 2371 if (swp_pager_swblk_empty(sb, 0, start) && 2372 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2373 swblk_iter_remove(&blks); 2374 uma_zfree(swblk_zone, sb); 2375 } 2376 } 2377 swp_pager_freeswapspace(&range); 2378 out: 2379 if (freed != NULL) 2380 *freed = fc; 2381 } 2382 2383 static void 2384 swp_pager_meta_free_block(struct swblk *sb, void *rangev) 2385 { 2386 struct page_range *range = rangev; 2387 2388 for (int i = 0; i < SWAP_META_PAGES; i++) { 2389 if (sb->d[i] != SWAPBLK_NONE) 2390 swp_pager_update_freerange(range, sb->d[i]); 2391 } 2392 uma_zfree(swblk_zone, sb); 2393 } 2394 2395 /* 2396 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2397 * 2398 * This routine locates and destroys all swap metadata associated with 2399 * an object. 2400 */ 2401 static void 2402 swp_pager_meta_free_all(vm_object_t object) 2403 { 2404 struct page_range range; 2405 2406 VM_OBJECT_ASSERT_WLOCKED(object); 2407 2408 swp_pager_init_freerange(&range); 2409 SWAP_PCTRIE_RECLAIM_CALLBACK(&object->un_pager.swp.swp_blks, 2410 swp_pager_meta_free_block, &range); 2411 swp_pager_freeswapspace(&range); 2412 } 2413 2414 /* 2415 * SWP_PAGER_METACTL() - misc control of swap meta data. 2416 * 2417 * This routine is capable of looking up, or removing swapblk 2418 * assignments in the swap meta data. It returns the swapblk being 2419 * looked-up, popped, or SWAPBLK_NONE if the block was invalid. 2420 * 2421 * When acting on a busy resident page and paging is in progress, we 2422 * have to wait until paging is complete but otherwise can act on the 2423 * busy page. 2424 */ 2425 static daddr_t 2426 swp_pager_meta_lookup(vm_object_t object, vm_pindex_t pindex) 2427 { 2428 struct swblk *sb; 2429 2430 VM_OBJECT_ASSERT_LOCKED(object); 2431 2432 /* 2433 * The meta data only exists if the object is OBJT_SWAP 2434 * and even then might not be allocated yet. 2435 */ 2436 KASSERT((object->flags & OBJ_SWAP) != 0, 2437 ("Lookup object not swappable")); 2438 2439 sb = swblk_lookup(object, pindex); 2440 if (sb == NULL) 2441 return (SWAPBLK_NONE); 2442 return (sb->d[pindex % SWAP_META_PAGES]); 2443 } 2444 2445 /* 2446 * Returns the least page index which is greater than or equal to the parameter 2447 * pindex and for which there is a swap block allocated. Returns OBJ_MAX_SIZE 2448 * if are no allocated swap blocks for the object after the requested pindex. 2449 */ 2450 static vm_pindex_t 2451 swap_pager_iter_find_least(struct pctrie_iter *blks, vm_pindex_t pindex) 2452 { 2453 struct swblk *sb; 2454 int i; 2455 2456 if ((sb = swblk_iter_lookup_ge(blks, pindex)) == NULL) 2457 return (OBJ_MAX_SIZE); 2458 if (blks->index < pindex) { 2459 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2460 if (sb->d[i] != SWAPBLK_NONE) 2461 return (blks->index + i); 2462 } 2463 if ((sb = swblk_iter_next(blks)) == NULL) 2464 return (OBJ_MAX_SIZE); 2465 } 2466 for (i = 0; i < SWAP_META_PAGES; i++) { 2467 if (sb->d[i] != SWAPBLK_NONE) 2468 return (blks->index + i); 2469 } 2470 2471 /* 2472 * We get here if a swblk is present in the trie but it 2473 * doesn't map any blocks. 2474 */ 2475 MPASS(0); 2476 return (OBJ_MAX_SIZE); 2477 } 2478 2479 /* 2480 * Find the first index >= pindex that has either a valid page or a swap 2481 * block. 2482 */ 2483 vm_pindex_t 2484 swap_pager_seek_data(vm_object_t object, vm_pindex_t pindex) 2485 { 2486 struct pctrie_iter blks, pages; 2487 vm_page_t m; 2488 vm_pindex_t swap_index; 2489 2490 VM_OBJECT_ASSERT_RLOCKED(object); 2491 vm_page_iter_init(&pages, object); 2492 m = vm_page_iter_lookup_ge(&pages, pindex); 2493 if (m != NULL) { 2494 if (!vm_page_any_valid(m)) 2495 m = NULL; 2496 else if (pages.index == pindex) 2497 return (pages.index); 2498 } 2499 swblk_iter_init_only(&blks, object); 2500 swap_index = swap_pager_iter_find_least(&blks, pindex); 2501 if (swap_index == pindex) 2502 return (swap_index); 2503 if (swap_index == OBJ_MAX_SIZE) 2504 swap_index = object->size; 2505 if (m == NULL) 2506 return (swap_index); 2507 2508 while ((m = vm_radix_iter_step(&pages)) != NULL && 2509 pages.index < swap_index) { 2510 if (vm_page_any_valid(m)) 2511 return (pages.index); 2512 } 2513 return (swap_index); 2514 } 2515 2516 /* 2517 * Find the first index >= pindex that has neither a valid page nor a swap 2518 * block. 2519 */ 2520 vm_pindex_t 2521 swap_pager_seek_hole(vm_object_t object, vm_pindex_t pindex) 2522 { 2523 struct pctrie_iter blks, pages; 2524 struct swblk *sb; 2525 vm_page_t m; 2526 2527 VM_OBJECT_ASSERT_RLOCKED(object); 2528 vm_page_iter_init(&pages, object); 2529 swblk_iter_init_only(&blks, object); 2530 while (((m = vm_page_iter_lookup(&pages, pindex)) != NULL && 2531 vm_page_any_valid(m)) || 2532 ((sb = swblk_iter_lookup(&blks, pindex)) != NULL && 2533 sb->d[pindex % SWAP_META_PAGES] != SWAPBLK_NONE)) 2534 pindex++; 2535 return (pindex); 2536 } 2537 2538 /* 2539 * Is every page in the backing object or swap shadowed in the parent, and 2540 * unbusy and valid in swap? 2541 */ 2542 bool 2543 swap_pager_scan_all_shadowed(vm_object_t object) 2544 { 2545 struct pctrie_iter backing_blks, backing_pages, pages; 2546 vm_object_t backing_object; 2547 vm_page_t p, pp; 2548 vm_pindex_t backing_offset_index, new_pindex, pi, pi_ubound, ps, pv; 2549 2550 VM_OBJECT_ASSERT_WLOCKED(object); 2551 VM_OBJECT_ASSERT_WLOCKED(object->backing_object); 2552 2553 backing_object = object->backing_object; 2554 2555 if ((backing_object->flags & OBJ_ANON) == 0) 2556 return (false); 2557 2558 KASSERT((object->flags & OBJ_ANON) != 0, 2559 ("Shadow object is not anonymous")); 2560 backing_offset_index = OFF_TO_IDX(object->backing_object_offset); 2561 pi_ubound = MIN(backing_object->size, 2562 backing_offset_index + object->size); 2563 vm_page_iter_init(&pages, object); 2564 vm_page_iter_init(&backing_pages, backing_object); 2565 swblk_iter_init_only(&backing_blks, backing_object); 2566 2567 /* 2568 * Only check pages inside the parent object's range and inside the 2569 * parent object's mapping of the backing object. 2570 */ 2571 pv = ps = pi = backing_offset_index - 1; 2572 for (;;) { 2573 if (pi == pv) { 2574 p = vm_page_iter_lookup_ge(&backing_pages, pv + 1); 2575 pv = p != NULL ? p->pindex : backing_object->size; 2576 } 2577 if (pi == ps) 2578 ps = swap_pager_iter_find_least(&backing_blks, ps + 1); 2579 pi = MIN(pv, ps); 2580 if (pi >= pi_ubound) 2581 break; 2582 2583 if (pi == pv) { 2584 /* 2585 * If the backing object page is busy a grandparent or 2586 * older page may still be undergoing CoW. It is not 2587 * safe to collapse the backing object until it is 2588 * quiesced. 2589 */ 2590 if (vm_page_tryxbusy(p) == 0) 2591 return (false); 2592 2593 /* 2594 * We raced with the fault handler that left newly 2595 * allocated invalid page on the object queue and 2596 * retried. 2597 */ 2598 if (!vm_page_all_valid(p)) 2599 break; 2600 2601 /* 2602 * Busy of p disallows fault handler to validate parent 2603 * page (pp, below). 2604 */ 2605 } 2606 2607 /* 2608 * See if the parent has the page or if the parent's object 2609 * pager has the page. If the parent has the page but the page 2610 * is not valid, the parent's object pager must have the page. 2611 * 2612 * If this fails, the parent does not completely shadow the 2613 * object and we might as well give up now. 2614 */ 2615 new_pindex = pi - backing_offset_index; 2616 pp = vm_page_iter_lookup(&pages, new_pindex); 2617 2618 /* 2619 * The valid check here is stable due to object lock being 2620 * required to clear valid and initiate paging. 2621 */ 2622 if ((pp == NULL || vm_page_none_valid(pp)) && 2623 !swap_pager_haspage(object, new_pindex, NULL, NULL)) 2624 break; 2625 if (pi == pv) 2626 vm_page_xunbusy(p); 2627 } 2628 if (pi < pi_ubound) { 2629 if (pi == pv) 2630 vm_page_xunbusy(p); 2631 return (false); 2632 } 2633 return (true); 2634 } 2635 2636 /* 2637 * System call swapon(name) enables swapping on device name, 2638 * which must be in the swdevsw. Return EBUSY 2639 * if already swapping on this device. 2640 */ 2641 #ifndef _SYS_SYSPROTO_H_ 2642 struct swapon_args { 2643 char *name; 2644 }; 2645 #endif 2646 2647 int 2648 sys_swapon(struct thread *td, struct swapon_args *uap) 2649 { 2650 struct vattr attr; 2651 struct vnode *vp; 2652 struct nameidata nd; 2653 int error; 2654 2655 error = priv_check(td, PRIV_SWAPON); 2656 if (error) 2657 return (error); 2658 2659 sx_xlock(&swdev_syscall_lock); 2660 2661 /* 2662 * Swap metadata may not fit in the KVM if we have physical 2663 * memory of >1GB. 2664 */ 2665 if (swblk_zone == NULL) { 2666 error = ENOMEM; 2667 goto done; 2668 } 2669 2670 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | LOCKLEAF | AUDITVNODE1, 2671 UIO_USERSPACE, uap->name); 2672 error = namei(&nd); 2673 if (error) 2674 goto done; 2675 2676 NDFREE_PNBUF(&nd); 2677 vp = nd.ni_vp; 2678 2679 if (vn_isdisk_error(vp, &error)) { 2680 error = swapongeom(vp); 2681 } else if (vp->v_type == VREG && 2682 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2683 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2684 /* 2685 * Allow direct swapping to NFS regular files in the same 2686 * way that nfs_mountroot() sets up diskless swapping. 2687 */ 2688 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2689 } 2690 2691 if (error != 0) 2692 vput(vp); 2693 else 2694 VOP_UNLOCK(vp); 2695 done: 2696 sx_xunlock(&swdev_syscall_lock); 2697 return (error); 2698 } 2699 2700 /* 2701 * Check that the total amount of swap currently configured does not 2702 * exceed half the theoretical maximum. If it does, print a warning 2703 * message. 2704 */ 2705 static void 2706 swapon_check_swzone(void) 2707 { 2708 2709 /* recommend using no more than half that amount */ 2710 if (swap_total > swap_maxpages / 2) { 2711 printf("warning: total configured swap (%lu pages) " 2712 "exceeds maximum recommended amount (%lu pages).\n", 2713 swap_total, swap_maxpages / 2); 2714 printf("warning: increase kern.maxswzone " 2715 "or reduce amount of swap.\n"); 2716 } 2717 } 2718 2719 static void 2720 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2721 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2722 { 2723 struct swdevt *sp, *tsp; 2724 daddr_t dvbase; 2725 2726 /* 2727 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2728 * First chop nblks off to page-align it, then convert. 2729 * 2730 * sw->sw_nblks is in page-sized chunks now too. 2731 */ 2732 nblks &= ~(ctodb(1) - 1); 2733 nblks = dbtoc(nblks); 2734 2735 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2736 sp->sw_blist = blist_create(nblks, M_WAITOK); 2737 sp->sw_vp = vp; 2738 sp->sw_id = id; 2739 sp->sw_dev = dev; 2740 sp->sw_nblks = nblks; 2741 sp->sw_used = 0; 2742 sp->sw_strategy = strategy; 2743 sp->sw_close = close; 2744 sp->sw_flags = flags; 2745 2746 /* 2747 * Do not free the first blocks in order to avoid overwriting 2748 * any bsd label at the front of the partition 2749 */ 2750 blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE), 2751 nblks - howmany(BBSIZE, PAGE_SIZE)); 2752 2753 dvbase = 0; 2754 mtx_lock(&sw_dev_mtx); 2755 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2756 if (tsp->sw_end >= dvbase) { 2757 /* 2758 * We put one uncovered page between the devices 2759 * in order to definitively prevent any cross-device 2760 * I/O requests 2761 */ 2762 dvbase = tsp->sw_end + 1; 2763 } 2764 } 2765 sp->sw_first = dvbase; 2766 sp->sw_end = dvbase + nblks; 2767 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2768 nswapdev++; 2769 swap_pager_avail += nblks - howmany(BBSIZE, PAGE_SIZE); 2770 swap_total += nblks; 2771 swapon_check_swzone(); 2772 swp_sizecheck(); 2773 mtx_unlock(&sw_dev_mtx); 2774 EVENTHANDLER_INVOKE(swapon, sp); 2775 } 2776 2777 /* 2778 * SYSCALL: swapoff(devname) 2779 * 2780 * Disable swapping on the given device. 2781 * 2782 * XXX: Badly designed system call: it should use a device index 2783 * rather than filename as specification. We keep sw_vp around 2784 * only to make this work. 2785 */ 2786 static int 2787 kern_swapoff(struct thread *td, const char *name, enum uio_seg name_seg, 2788 u_int flags) 2789 { 2790 struct vnode *vp; 2791 struct nameidata nd; 2792 struct swdevt *sp; 2793 int error; 2794 2795 error = priv_check(td, PRIV_SWAPOFF); 2796 if (error != 0) 2797 return (error); 2798 if ((flags & ~(SWAPOFF_FORCE)) != 0) 2799 return (EINVAL); 2800 2801 sx_xlock(&swdev_syscall_lock); 2802 2803 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, name_seg, name); 2804 error = namei(&nd); 2805 if (error) 2806 goto done; 2807 NDFREE_PNBUF(&nd); 2808 vp = nd.ni_vp; 2809 2810 mtx_lock(&sw_dev_mtx); 2811 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2812 if (sp->sw_vp == vp) 2813 break; 2814 } 2815 mtx_unlock(&sw_dev_mtx); 2816 if (sp == NULL) { 2817 error = EINVAL; 2818 goto done; 2819 } 2820 error = swapoff_one(sp, td->td_ucred, flags); 2821 done: 2822 sx_xunlock(&swdev_syscall_lock); 2823 return (error); 2824 } 2825 2826 2827 #ifdef COMPAT_FREEBSD13 2828 int 2829 freebsd13_swapoff(struct thread *td, struct freebsd13_swapoff_args *uap) 2830 { 2831 return (kern_swapoff(td, uap->name, UIO_USERSPACE, 0)); 2832 } 2833 #endif 2834 2835 int 2836 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2837 { 2838 return (kern_swapoff(td, uap->name, UIO_USERSPACE, uap->flags)); 2839 } 2840 2841 static int 2842 swapoff_one(struct swdevt *sp, struct ucred *cred, u_int flags) 2843 { 2844 u_long nblks; 2845 #ifdef MAC 2846 int error; 2847 #endif 2848 2849 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2850 #ifdef MAC 2851 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2852 error = mac_system_check_swapoff(cred, sp->sw_vp); 2853 (void) VOP_UNLOCK(sp->sw_vp); 2854 if (error != 0) 2855 return (error); 2856 #endif 2857 nblks = sp->sw_nblks; 2858 2859 /* 2860 * We can turn off this swap device safely only if the 2861 * available virtual memory in the system will fit the amount 2862 * of data we will have to page back in, plus an epsilon so 2863 * the system doesn't become critically low on swap space. 2864 * The vm_free_count() part does not account e.g. for clean 2865 * pages that can be immediately reclaimed without paging, so 2866 * this is a very rough estimation. 2867 * 2868 * On the other hand, not turning swap off on swapoff_all() 2869 * means that we can lose swap data when filesystems go away, 2870 * which is arguably worse. 2871 */ 2872 if ((flags & SWAPOFF_FORCE) == 0 && 2873 vm_free_count() + swap_pager_avail < nblks + nswap_lowat) 2874 return (ENOMEM); 2875 2876 /* 2877 * Prevent further allocations on this device. 2878 */ 2879 mtx_lock(&sw_dev_mtx); 2880 sp->sw_flags |= SW_CLOSING; 2881 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2882 swap_total -= nblks; 2883 mtx_unlock(&sw_dev_mtx); 2884 2885 /* 2886 * Page in the contents of the device and close it. 2887 */ 2888 swap_pager_swapoff(sp); 2889 2890 sp->sw_close(curthread, sp); 2891 mtx_lock(&sw_dev_mtx); 2892 sp->sw_id = NULL; 2893 TAILQ_REMOVE(&swtailq, sp, sw_list); 2894 nswapdev--; 2895 if (nswapdev == 0) { 2896 swap_pager_full = 2; 2897 swap_pager_almost_full = 1; 2898 } 2899 if (swdevhd == sp) 2900 swdevhd = NULL; 2901 mtx_unlock(&sw_dev_mtx); 2902 blist_destroy(sp->sw_blist); 2903 free(sp, M_VMPGDATA); 2904 return (0); 2905 } 2906 2907 void 2908 swapoff_all(void) 2909 { 2910 struct swdevt *sp, *spt; 2911 const char *devname; 2912 int error; 2913 2914 sx_xlock(&swdev_syscall_lock); 2915 2916 mtx_lock(&sw_dev_mtx); 2917 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2918 mtx_unlock(&sw_dev_mtx); 2919 if (vn_isdisk(sp->sw_vp)) 2920 devname = devtoname(sp->sw_vp->v_rdev); 2921 else 2922 devname = "[file]"; 2923 error = swapoff_one(sp, thread0.td_ucred, SWAPOFF_FORCE); 2924 if (error != 0) { 2925 printf("Cannot remove swap device %s (error=%d), " 2926 "skipping.\n", devname, error); 2927 } else if (bootverbose) { 2928 printf("Swap device %s removed.\n", devname); 2929 } 2930 mtx_lock(&sw_dev_mtx); 2931 } 2932 mtx_unlock(&sw_dev_mtx); 2933 2934 sx_xunlock(&swdev_syscall_lock); 2935 } 2936 2937 void 2938 swap_pager_status(int *total, int *used) 2939 { 2940 2941 *total = swap_total; 2942 *used = swap_total - swap_pager_avail - 2943 nswapdev * howmany(BBSIZE, PAGE_SIZE); 2944 } 2945 2946 int 2947 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2948 { 2949 struct swdevt *sp; 2950 const char *tmp_devname; 2951 int error, n; 2952 2953 n = 0; 2954 error = ENOENT; 2955 mtx_lock(&sw_dev_mtx); 2956 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2957 if (n != name) { 2958 n++; 2959 continue; 2960 } 2961 xs->xsw_version = XSWDEV_VERSION; 2962 xs->xsw_dev = sp->sw_dev; 2963 xs->xsw_flags = sp->sw_flags; 2964 xs->xsw_nblks = sp->sw_nblks; 2965 xs->xsw_used = sp->sw_used; 2966 if (devname != NULL) { 2967 if (vn_isdisk(sp->sw_vp)) 2968 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2969 else 2970 tmp_devname = "[file]"; 2971 strncpy(devname, tmp_devname, len); 2972 } 2973 error = 0; 2974 break; 2975 } 2976 mtx_unlock(&sw_dev_mtx); 2977 return (error); 2978 } 2979 2980 #if defined(COMPAT_FREEBSD11) 2981 #define XSWDEV_VERSION_11 1 2982 struct xswdev11 { 2983 u_int xsw_version; 2984 uint32_t xsw_dev; 2985 int xsw_flags; 2986 int xsw_nblks; 2987 int xsw_used; 2988 }; 2989 #endif 2990 2991 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2992 struct xswdev32 { 2993 u_int xsw_version; 2994 u_int xsw_dev1, xsw_dev2; 2995 int xsw_flags; 2996 int xsw_nblks; 2997 int xsw_used; 2998 }; 2999 #endif 3000 3001 static int 3002 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 3003 { 3004 struct xswdev xs; 3005 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 3006 struct xswdev32 xs32; 3007 #endif 3008 #if defined(COMPAT_FREEBSD11) 3009 struct xswdev11 xs11; 3010 #endif 3011 int error; 3012 3013 if (arg2 != 1) /* name length */ 3014 return (EINVAL); 3015 3016 memset(&xs, 0, sizeof(xs)); 3017 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 3018 if (error != 0) 3019 return (error); 3020 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 3021 if (req->oldlen == sizeof(xs32)) { 3022 memset(&xs32, 0, sizeof(xs32)); 3023 xs32.xsw_version = XSWDEV_VERSION; 3024 xs32.xsw_dev1 = xs.xsw_dev; 3025 xs32.xsw_dev2 = xs.xsw_dev >> 32; 3026 xs32.xsw_flags = xs.xsw_flags; 3027 xs32.xsw_nblks = xs.xsw_nblks; 3028 xs32.xsw_used = xs.xsw_used; 3029 error = SYSCTL_OUT(req, &xs32, sizeof(xs32)); 3030 return (error); 3031 } 3032 #endif 3033 #if defined(COMPAT_FREEBSD11) 3034 if (req->oldlen == sizeof(xs11)) { 3035 memset(&xs11, 0, sizeof(xs11)); 3036 xs11.xsw_version = XSWDEV_VERSION_11; 3037 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 3038 xs11.xsw_flags = xs.xsw_flags; 3039 xs11.xsw_nblks = xs.xsw_nblks; 3040 xs11.xsw_used = xs.xsw_used; 3041 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 3042 return (error); 3043 } 3044 #endif 3045 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 3046 return (error); 3047 } 3048 3049 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 3050 "Number of swap devices"); 3051 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 3052 sysctl_vm_swap_info, 3053 "Swap statistics by device"); 3054 3055 /* 3056 * Count the approximate swap usage in pages for a vmspace. The 3057 * shadowed or not yet copied on write swap blocks are not accounted. 3058 * The map must be locked. 3059 */ 3060 long 3061 vmspace_swap_count(struct vmspace *vmspace) 3062 { 3063 struct pctrie_iter blks; 3064 vm_map_t map; 3065 vm_map_entry_t cur; 3066 vm_object_t object; 3067 struct swblk *sb; 3068 vm_pindex_t e, pi; 3069 long count; 3070 int i, limit, start; 3071 3072 map = &vmspace->vm_map; 3073 count = 0; 3074 3075 VM_MAP_ENTRY_FOREACH(cur, map) { 3076 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 3077 continue; 3078 object = cur->object.vm_object; 3079 if (object == NULL || (object->flags & OBJ_SWAP) == 0) 3080 continue; 3081 VM_OBJECT_RLOCK(object); 3082 if ((object->flags & OBJ_SWAP) == 0) 3083 goto unlock; 3084 pi = OFF_TO_IDX(cur->offset); 3085 e = pi + OFF_TO_IDX(cur->end - cur->start); 3086 for (sb = swblk_iter_limit_init(&blks, object, pi, e), 3087 start = swblk_start(sb, pi); 3088 sb != NULL; sb = swblk_iter_next(&blks), start = 0) { 3089 limit = MIN(e - blks.index, SWAP_META_PAGES); 3090 for (i = start; i < limit; i++) { 3091 if (sb->d[i] != SWAPBLK_NONE) 3092 count++; 3093 } 3094 } 3095 unlock: 3096 VM_OBJECT_RUNLOCK(object); 3097 } 3098 return (count); 3099 } 3100 3101 /* 3102 * GEOM backend 3103 * 3104 * Swapping onto disk devices. 3105 * 3106 */ 3107 3108 static g_orphan_t swapgeom_orphan; 3109 3110 static struct g_class g_swap_class = { 3111 .name = "SWAP", 3112 .version = G_VERSION, 3113 .orphan = swapgeom_orphan, 3114 }; 3115 3116 DECLARE_GEOM_CLASS(g_swap_class, g_class); 3117 3118 static void 3119 swapgeom_close_ev(void *arg, int flags) 3120 { 3121 struct g_consumer *cp; 3122 3123 cp = arg; 3124 g_access(cp, -1, -1, 0); 3125 g_detach(cp); 3126 g_destroy_consumer(cp); 3127 } 3128 3129 /* 3130 * Add a reference to the g_consumer for an inflight transaction. 3131 */ 3132 static void 3133 swapgeom_acquire(struct g_consumer *cp) 3134 { 3135 3136 mtx_assert(&sw_dev_mtx, MA_OWNED); 3137 cp->index++; 3138 } 3139 3140 /* 3141 * Remove a reference from the g_consumer. Post a close event if all 3142 * references go away, since the function might be called from the 3143 * biodone context. 3144 */ 3145 static void 3146 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 3147 { 3148 3149 mtx_assert(&sw_dev_mtx, MA_OWNED); 3150 cp->index--; 3151 if (cp->index == 0) { 3152 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 3153 sp->sw_id = NULL; 3154 } 3155 } 3156 3157 static void 3158 swapgeom_done(struct bio *bp2) 3159 { 3160 struct swdevt *sp; 3161 struct buf *bp; 3162 struct g_consumer *cp; 3163 3164 bp = bp2->bio_caller2; 3165 cp = bp2->bio_from; 3166 bp->b_ioflags = bp2->bio_flags; 3167 if (bp2->bio_error) 3168 bp->b_ioflags |= BIO_ERROR; 3169 bp->b_resid = bp->b_bcount - bp2->bio_completed; 3170 bp->b_error = bp2->bio_error; 3171 bp->b_caller1 = NULL; 3172 bufdone(bp); 3173 sp = bp2->bio_caller1; 3174 mtx_lock(&sw_dev_mtx); 3175 swapgeom_release(cp, sp); 3176 mtx_unlock(&sw_dev_mtx); 3177 g_destroy_bio(bp2); 3178 } 3179 3180 static void 3181 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 3182 { 3183 struct bio *bio; 3184 struct g_consumer *cp; 3185 3186 mtx_lock(&sw_dev_mtx); 3187 cp = sp->sw_id; 3188 if (cp == NULL) { 3189 mtx_unlock(&sw_dev_mtx); 3190 bp->b_error = ENXIO; 3191 bp->b_ioflags |= BIO_ERROR; 3192 bufdone(bp); 3193 return; 3194 } 3195 swapgeom_acquire(cp); 3196 mtx_unlock(&sw_dev_mtx); 3197 if (bp->b_iocmd == BIO_WRITE) 3198 bio = g_new_bio(); 3199 else 3200 bio = g_alloc_bio(); 3201 if (bio == NULL) { 3202 mtx_lock(&sw_dev_mtx); 3203 swapgeom_release(cp, sp); 3204 mtx_unlock(&sw_dev_mtx); 3205 bp->b_error = ENOMEM; 3206 bp->b_ioflags |= BIO_ERROR; 3207 printf("swap_pager: cannot allocate bio\n"); 3208 bufdone(bp); 3209 return; 3210 } 3211 3212 bp->b_caller1 = bio; 3213 bio->bio_caller1 = sp; 3214 bio->bio_caller2 = bp; 3215 bio->bio_cmd = bp->b_iocmd; 3216 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 3217 bio->bio_length = bp->b_bcount; 3218 bio->bio_done = swapgeom_done; 3219 bio->bio_flags |= BIO_SWAP; 3220 if (!buf_mapped(bp)) { 3221 bio->bio_ma = bp->b_pages; 3222 bio->bio_data = unmapped_buf; 3223 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 3224 bio->bio_ma_n = bp->b_npages; 3225 bio->bio_flags |= BIO_UNMAPPED; 3226 } else { 3227 bio->bio_data = bp->b_data; 3228 bio->bio_ma = NULL; 3229 } 3230 g_io_request(bio, cp); 3231 return; 3232 } 3233 3234 static void 3235 swapgeom_orphan(struct g_consumer *cp) 3236 { 3237 struct swdevt *sp; 3238 int destroy; 3239 3240 mtx_lock(&sw_dev_mtx); 3241 TAILQ_FOREACH(sp, &swtailq, sw_list) { 3242 if (sp->sw_id == cp) { 3243 sp->sw_flags |= SW_CLOSING; 3244 break; 3245 } 3246 } 3247 /* 3248 * Drop reference we were created with. Do directly since we're in a 3249 * special context where we don't have to queue the call to 3250 * swapgeom_close_ev(). 3251 */ 3252 cp->index--; 3253 destroy = ((sp != NULL) && (cp->index == 0)); 3254 if (destroy) 3255 sp->sw_id = NULL; 3256 mtx_unlock(&sw_dev_mtx); 3257 if (destroy) 3258 swapgeom_close_ev(cp, 0); 3259 } 3260 3261 static void 3262 swapgeom_close(struct thread *td, struct swdevt *sw) 3263 { 3264 struct g_consumer *cp; 3265 3266 mtx_lock(&sw_dev_mtx); 3267 cp = sw->sw_id; 3268 sw->sw_id = NULL; 3269 mtx_unlock(&sw_dev_mtx); 3270 3271 /* 3272 * swapgeom_close() may be called from the biodone context, 3273 * where we cannot perform topology changes. Delegate the 3274 * work to the events thread. 3275 */ 3276 if (cp != NULL) 3277 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 3278 } 3279 3280 static int 3281 swapongeom_locked(struct cdev *dev, struct vnode *vp) 3282 { 3283 struct g_provider *pp; 3284 struct g_consumer *cp; 3285 static struct g_geom *gp; 3286 struct swdevt *sp; 3287 u_long nblks; 3288 int error; 3289 3290 pp = g_dev_getprovider(dev); 3291 if (pp == NULL) 3292 return (ENODEV); 3293 mtx_lock(&sw_dev_mtx); 3294 TAILQ_FOREACH(sp, &swtailq, sw_list) { 3295 cp = sp->sw_id; 3296 if (cp != NULL && cp->provider == pp) { 3297 mtx_unlock(&sw_dev_mtx); 3298 return (EBUSY); 3299 } 3300 } 3301 mtx_unlock(&sw_dev_mtx); 3302 if (gp == NULL) 3303 gp = g_new_geomf(&g_swap_class, "swap"); 3304 cp = g_new_consumer(gp); 3305 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 3306 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 3307 g_attach(cp, pp); 3308 /* 3309 * XXX: Every time you think you can improve the margin for 3310 * footshooting, somebody depends on the ability to do so: 3311 * savecore(8) wants to write to our swapdev so we cannot 3312 * set an exclusive count :-( 3313 */ 3314 error = g_access(cp, 1, 1, 0); 3315 if (error != 0) { 3316 g_detach(cp); 3317 g_destroy_consumer(cp); 3318 return (error); 3319 } 3320 nblks = pp->mediasize / DEV_BSIZE; 3321 swaponsomething(vp, cp, nblks, swapgeom_strategy, 3322 swapgeom_close, dev2udev(dev), 3323 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 3324 return (0); 3325 } 3326 3327 static int 3328 swapongeom(struct vnode *vp) 3329 { 3330 int error; 3331 3332 ASSERT_VOP_ELOCKED(vp, "swapongeom"); 3333 if (vp->v_type != VCHR || VN_IS_DOOMED(vp)) { 3334 error = ENOENT; 3335 } else { 3336 g_topology_lock(); 3337 error = swapongeom_locked(vp->v_rdev, vp); 3338 g_topology_unlock(); 3339 } 3340 return (error); 3341 } 3342 3343 /* 3344 * VNODE backend 3345 * 3346 * This is used mainly for network filesystem (read: probably only tested 3347 * with NFS) swapfiles. 3348 * 3349 */ 3350 3351 static void 3352 swapdev_strategy(struct buf *bp, struct swdevt *sp) 3353 { 3354 struct vnode *vp2; 3355 3356 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 3357 3358 vp2 = sp->sw_id; 3359 vhold(vp2); 3360 if (bp->b_iocmd == BIO_WRITE) { 3361 vn_lock(vp2, LK_EXCLUSIVE | LK_RETRY); 3362 if (bp->b_bufobj) 3363 bufobj_wdrop(bp->b_bufobj); 3364 bufobj_wref(&vp2->v_bufobj); 3365 } else { 3366 vn_lock(vp2, LK_SHARED | LK_RETRY); 3367 } 3368 if (bp->b_bufobj != &vp2->v_bufobj) 3369 bp->b_bufobj = &vp2->v_bufobj; 3370 bp->b_vp = vp2; 3371 bp->b_iooffset = dbtob(bp->b_blkno); 3372 bstrategy(bp); 3373 VOP_UNLOCK(vp2); 3374 } 3375 3376 static void 3377 swapdev_close(struct thread *td, struct swdevt *sp) 3378 { 3379 struct vnode *vp; 3380 3381 vp = sp->sw_vp; 3382 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 3383 VOP_CLOSE(vp, FREAD | FWRITE, td->td_ucred, td); 3384 vput(vp); 3385 } 3386 3387 static int 3388 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 3389 { 3390 struct swdevt *sp; 3391 int error; 3392 3393 ASSERT_VOP_ELOCKED(vp, "swaponvp"); 3394 if (nblks == 0) 3395 return (ENXIO); 3396 mtx_lock(&sw_dev_mtx); 3397 TAILQ_FOREACH(sp, &swtailq, sw_list) { 3398 if (sp->sw_id == vp) { 3399 mtx_unlock(&sw_dev_mtx); 3400 return (EBUSY); 3401 } 3402 } 3403 mtx_unlock(&sw_dev_mtx); 3404 3405 #ifdef MAC 3406 error = mac_system_check_swapon(td->td_ucred, vp); 3407 if (error == 0) 3408 #endif 3409 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 3410 if (error != 0) 3411 return (error); 3412 3413 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 3414 NODEV, 0); 3415 return (0); 3416 } 3417 3418 static int 3419 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 3420 { 3421 int error, new, n; 3422 3423 new = nsw_wcount_async_max; 3424 error = sysctl_handle_int(oidp, &new, 0, req); 3425 if (error != 0 || req->newptr == NULL) 3426 return (error); 3427 3428 if (new > nswbuf / 2 || new < 1) 3429 return (EINVAL); 3430 3431 mtx_lock(&swbuf_mtx); 3432 while (nsw_wcount_async_max != new) { 3433 /* 3434 * Adjust difference. If the current async count is too low, 3435 * we will need to sqeeze our update slowly in. Sleep with a 3436 * higher priority than getpbuf() to finish faster. 3437 */ 3438 n = new - nsw_wcount_async_max; 3439 if (nsw_wcount_async + n >= 0) { 3440 nsw_wcount_async += n; 3441 nsw_wcount_async_max += n; 3442 wakeup(&nsw_wcount_async); 3443 } else { 3444 nsw_wcount_async_max -= nsw_wcount_async; 3445 nsw_wcount_async = 0; 3446 msleep(&nsw_wcount_async, &swbuf_mtx, PSWP, 3447 "swpsysctl", 0); 3448 } 3449 } 3450 mtx_unlock(&swbuf_mtx); 3451 3452 return (0); 3453 } 3454 3455 static void 3456 swap_pager_update_writecount(vm_object_t object, vm_offset_t start, 3457 vm_offset_t end) 3458 { 3459 3460 VM_OBJECT_WLOCK(object); 3461 KASSERT((object->flags & OBJ_ANON) == 0, 3462 ("Splittable object with writecount")); 3463 object->un_pager.swp.writemappings += (vm_ooffset_t)end - start; 3464 VM_OBJECT_WUNLOCK(object); 3465 } 3466 3467 static void 3468 swap_pager_release_writecount(vm_object_t object, vm_offset_t start, 3469 vm_offset_t end) 3470 { 3471 3472 VM_OBJECT_WLOCK(object); 3473 KASSERT((object->flags & OBJ_ANON) == 0, 3474 ("Splittable object with writecount")); 3475 KASSERT(object->un_pager.swp.writemappings >= (vm_ooffset_t)end - start, 3476 ("swap obj %p writecount %jx dec %jx", object, 3477 (uintmax_t)object->un_pager.swp.writemappings, 3478 (uintmax_t)((vm_ooffset_t)end - start))); 3479 object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start; 3480 VM_OBJECT_WUNLOCK(object); 3481 } 3482