1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (c) 1998 Matthew Dillon, 5 * Copyright (c) 1994 John S. Dyson 6 * Copyright (c) 1990 University of Utah. 7 * Copyright (c) 1982, 1986, 1989, 1993 8 * The Regents of the University of California. All rights reserved. 9 * 10 * This code is derived from software contributed to Berkeley by 11 * the Systems Programming Group of the University of Utah Computer 12 * Science Department. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. All advertising materials mentioning features or use of this software 23 * must display the following acknowledgement: 24 * This product includes software developed by the University of 25 * California, Berkeley and its contributors. 26 * 4. Neither the name of the University nor the names of its contributors 27 * may be used to endorse or promote products derived from this software 28 * without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 40 * SUCH DAMAGE. 41 * 42 * New Swap System 43 * Matthew Dillon 44 * 45 * Radix Bitmap 'blists'. 46 * 47 * - The new swapper uses the new radix bitmap code. This should scale 48 * to arbitrarily small or arbitrarily large swap spaces and an almost 49 * arbitrary degree of fragmentation. 50 * 51 * Features: 52 * 53 * - on the fly reallocation of swap during putpages. The new system 54 * does not try to keep previously allocated swap blocks for dirty 55 * pages. 56 * 57 * - on the fly deallocation of swap 58 * 59 * - No more garbage collection required. Unnecessarily allocated swap 60 * blocks only exist for dirty vm_page_t's now and these are already 61 * cycled (in a high-load system) by the pager. We also do on-the-fly 62 * removal of invalidated swap blocks when a page is destroyed 63 * or renamed. 64 * 65 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$ 66 */ 67 68 #include <sys/cdefs.h> 69 #include "opt_vm.h" 70 71 #include <sys/param.h> 72 #include <sys/bio.h> 73 #include <sys/blist.h> 74 #include <sys/buf.h> 75 #include <sys/conf.h> 76 #include <sys/disk.h> 77 #include <sys/disklabel.h> 78 #include <sys/eventhandler.h> 79 #include <sys/fcntl.h> 80 #include <sys/limits.h> 81 #include <sys/lock.h> 82 #include <sys/kernel.h> 83 #include <sys/mount.h> 84 #include <sys/namei.h> 85 #include <sys/malloc.h> 86 #include <sys/pctrie.h> 87 #include <sys/priv.h> 88 #include <sys/proc.h> 89 #include <sys/racct.h> 90 #include <sys/resource.h> 91 #include <sys/resourcevar.h> 92 #include <sys/rwlock.h> 93 #include <sys/sbuf.h> 94 #include <sys/sysctl.h> 95 #include <sys/sysproto.h> 96 #include <sys/systm.h> 97 #include <sys/sx.h> 98 #include <sys/unistd.h> 99 #include <sys/user.h> 100 #include <sys/vmmeter.h> 101 #include <sys/vnode.h> 102 103 #include <security/mac/mac_framework.h> 104 105 #include <vm/vm.h> 106 #include <vm/pmap.h> 107 #include <vm/vm_map.h> 108 #include <vm/vm_kern.h> 109 #include <vm/vm_object.h> 110 #include <vm/vm_page.h> 111 #include <vm/vm_pager.h> 112 #include <vm/vm_pageout.h> 113 #include <vm/vm_param.h> 114 #include <vm/swap_pager.h> 115 #include <vm/vm_extern.h> 116 #include <vm/uma.h> 117 118 #include <geom/geom.h> 119 120 /* 121 * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64. 122 * The 64-page limit is due to the radix code (kern/subr_blist.c). 123 */ 124 #ifndef MAX_PAGEOUT_CLUSTER 125 #define MAX_PAGEOUT_CLUSTER 32 126 #endif 127 128 #if !defined(SWB_NPAGES) 129 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER 130 #endif 131 132 #define SWAP_META_PAGES PCTRIE_COUNT 133 134 /* 135 * A swblk structure maps each page index within a 136 * SWAP_META_PAGES-aligned and sized range to the address of an 137 * on-disk swap block (or SWAPBLK_NONE). The collection of these 138 * mappings for an entire vm object is implemented as a pc-trie. 139 */ 140 struct swblk { 141 vm_pindex_t p; 142 daddr_t d[SWAP_META_PAGES]; 143 }; 144 145 /* 146 * A page_range structure records the start address and length of a sequence of 147 * mapped page addresses. 148 */ 149 struct page_range { 150 daddr_t start; 151 daddr_t num; 152 }; 153 154 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); 155 static struct mtx sw_dev_mtx; 156 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 157 static struct swdevt *swdevhd; /* Allocate from here next */ 158 static int nswapdev; /* Number of swap devices */ 159 int swap_pager_avail; 160 static struct sx swdev_syscall_lock; /* serialize swap(on|off) */ 161 162 static __exclusive_cache_line u_long swap_reserved; 163 static u_long swap_total; 164 static int sysctl_page_shift(SYSCTL_HANDLER_ARGS); 165 166 static SYSCTL_NODE(_vm_stats, OID_AUTO, swap, CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 167 "VM swap stats"); 168 169 SYSCTL_PROC(_vm, OID_AUTO, swap_reserved, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 170 &swap_reserved, 0, sysctl_page_shift, "QU", 171 "Amount of swap storage needed to back all allocated anonymous memory."); 172 SYSCTL_PROC(_vm, OID_AUTO, swap_total, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 173 &swap_total, 0, sysctl_page_shift, "QU", 174 "Total amount of available swap storage."); 175 176 int vm_overcommit __read_mostly = 0; 177 SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &vm_overcommit, 0, 178 "Configure virtual memory overcommit behavior. See tuning(7) " 179 "for details."); 180 static unsigned long swzone; 181 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 182 "Actual size of swap metadata zone"); 183 static unsigned long swap_maxpages; 184 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, 185 "Maximum amount of swap supported"); 186 187 static COUNTER_U64_DEFINE_EARLY(swap_free_deferred); 188 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_deferred, 189 CTLFLAG_RD, &swap_free_deferred, 190 "Number of pages that deferred freeing swap space"); 191 192 static COUNTER_U64_DEFINE_EARLY(swap_free_completed); 193 SYSCTL_COUNTER_U64(_vm_stats_swap, OID_AUTO, free_completed, 194 CTLFLAG_RD, &swap_free_completed, 195 "Number of deferred frees completed"); 196 197 static int 198 sysctl_page_shift(SYSCTL_HANDLER_ARGS) 199 { 200 uint64_t newval; 201 u_long value = *(u_long *)arg1; 202 203 newval = ((uint64_t)value) << PAGE_SHIFT; 204 return (sysctl_handle_64(oidp, &newval, 0, req)); 205 } 206 207 static bool 208 swap_reserve_by_cred_rlimit(u_long pincr, struct ucred *cred, int oc) 209 { 210 struct uidinfo *uip; 211 u_long prev; 212 213 uip = cred->cr_ruidinfo; 214 215 prev = atomic_fetchadd_long(&uip->ui_vmsize, pincr); 216 if ((oc & SWAP_RESERVE_RLIMIT_ON) != 0 && 217 prev + pincr > lim_cur(curthread, RLIMIT_SWAP) && 218 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT) != 0) { 219 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pincr); 220 KASSERT(prev >= pincr, 221 ("negative vmsize for uid %d\n", uip->ui_uid)); 222 return (false); 223 } 224 return (true); 225 } 226 227 static void 228 swap_release_by_cred_rlimit(u_long pdecr, struct ucred *cred) 229 { 230 struct uidinfo *uip; 231 #ifdef INVARIANTS 232 u_long prev; 233 #endif 234 235 uip = cred->cr_ruidinfo; 236 237 #ifdef INVARIANTS 238 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pdecr); 239 KASSERT(prev >= pdecr, 240 ("negative vmsize for uid %d\n", uip->ui_uid)); 241 #else 242 atomic_subtract_long(&uip->ui_vmsize, pdecr); 243 #endif 244 } 245 246 static void 247 swap_reserve_force_rlimit(u_long pincr, struct ucred *cred) 248 { 249 struct uidinfo *uip; 250 251 uip = cred->cr_ruidinfo; 252 atomic_add_long(&uip->ui_vmsize, pincr); 253 } 254 255 bool 256 swap_reserve(vm_ooffset_t incr) 257 { 258 259 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 260 } 261 262 bool 263 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 264 { 265 u_long r, s, prev, pincr; 266 #ifdef RACCT 267 int error; 268 #endif 269 int oc; 270 static int curfail; 271 static struct timeval lastfail; 272 273 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", 274 __func__, (uintmax_t)incr)); 275 276 #ifdef RACCT 277 if (RACCT_ENABLED()) { 278 PROC_LOCK(curproc); 279 error = racct_add(curproc, RACCT_SWAP, incr); 280 PROC_UNLOCK(curproc); 281 if (error != 0) 282 return (false); 283 } 284 #endif 285 286 pincr = atop(incr); 287 prev = atomic_fetchadd_long(&swap_reserved, pincr); 288 r = prev + pincr; 289 s = swap_total; 290 oc = atomic_load_int(&vm_overcommit); 291 if (r > s && (oc & SWAP_RESERVE_ALLOW_NONWIRED) != 0) { 292 s += vm_cnt.v_page_count - vm_cnt.v_free_reserved - 293 vm_wire_count(); 294 } 295 if ((oc & SWAP_RESERVE_FORCE_ON) != 0 && r > s && 296 priv_check(curthread, PRIV_VM_SWAP_NOQUOTA) != 0) { 297 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 298 KASSERT(prev >= pincr, 299 ("swap_reserved < incr on overcommit fail")); 300 goto out_error; 301 } 302 303 if (!swap_reserve_by_cred_rlimit(pincr, cred, oc)) { 304 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 305 KASSERT(prev >= pincr, 306 ("swap_reserved < incr on overcommit fail")); 307 goto out_error; 308 } 309 310 return (true); 311 312 out_error: 313 if (ppsratecheck(&lastfail, &curfail, 1)) { 314 printf("uid %d, pid %d: swap reservation " 315 "for %jd bytes failed\n", 316 cred->cr_ruidinfo->ui_uid, curproc->p_pid, incr); 317 } 318 #ifdef RACCT 319 if (RACCT_ENABLED()) { 320 PROC_LOCK(curproc); 321 racct_sub(curproc, RACCT_SWAP, incr); 322 PROC_UNLOCK(curproc); 323 } 324 #endif 325 326 return (false); 327 } 328 329 void 330 swap_reserve_force(vm_ooffset_t incr) 331 { 332 u_long pincr; 333 334 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", 335 __func__, (uintmax_t)incr)); 336 337 #ifdef RACCT 338 if (RACCT_ENABLED()) { 339 PROC_LOCK(curproc); 340 racct_add_force(curproc, RACCT_SWAP, incr); 341 PROC_UNLOCK(curproc); 342 } 343 #endif 344 pincr = atop(incr); 345 atomic_add_long(&swap_reserved, pincr); 346 swap_reserve_force_rlimit(pincr, curthread->td_ucred); 347 } 348 349 void 350 swap_release(vm_ooffset_t decr) 351 { 352 struct ucred *cred; 353 354 PROC_LOCK(curproc); 355 cred = curproc->p_ucred; 356 swap_release_by_cred(decr, cred); 357 PROC_UNLOCK(curproc); 358 } 359 360 void 361 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 362 { 363 u_long pdecr; 364 #ifdef INVARIANTS 365 u_long prev; 366 #endif 367 368 KASSERT((decr & PAGE_MASK) == 0, ("%s: decr: %ju & PAGE_MASK", 369 __func__, (uintmax_t)decr)); 370 371 pdecr = atop(decr); 372 #ifdef INVARIANTS 373 prev = atomic_fetchadd_long(&swap_reserved, -pdecr); 374 KASSERT(prev >= pdecr, ("swap_reserved < decr")); 375 #else 376 atomic_subtract_long(&swap_reserved, pdecr); 377 #endif 378 379 swap_release_by_cred_rlimit(pdecr, cred); 380 #ifdef RACCT 381 if (racct_enable) 382 racct_sub_cred(cred, RACCT_SWAP, decr); 383 #endif 384 } 385 386 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 387 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 388 static struct mtx swbuf_mtx; /* to sync nsw_wcount_async */ 389 static int nsw_wcount_async; /* limit async write buffers */ 390 static int nsw_wcount_async_max;/* assigned maximum */ 391 int nsw_cluster_max; /* maximum VOP I/O allowed */ 392 393 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 394 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 395 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 396 "Maximum running async swap ops"); 397 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS); 398 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD | 399 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A", 400 "Swap Fragmentation Info"); 401 402 static struct sx sw_alloc_sx; 403 404 /* 405 * "named" and "unnamed" anon region objects. Try to reduce the overhead 406 * of searching a named list by hashing it just a little. 407 */ 408 409 #define NOBJLISTS 8 410 411 #define NOBJLIST(handle) \ 412 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 413 414 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 415 static uma_zone_t swwbuf_zone; 416 static uma_zone_t swrbuf_zone; 417 static uma_zone_t swblk_zone; 418 static uma_zone_t swpctrie_zone; 419 420 /* 421 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 422 * calls hooked from other parts of the VM system and do not appear here. 423 * (see vm/swap_pager.h). 424 */ 425 static vm_object_t 426 swap_pager_alloc(void *handle, vm_ooffset_t size, 427 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 428 static void swap_pager_dealloc(vm_object_t object); 429 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, 430 int *); 431 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, 432 int *, pgo_getpages_iodone_t, void *); 433 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, int, int *); 434 static boolean_t 435 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 436 static void swap_pager_init(void); 437 static void swap_pager_unswapped(vm_page_t); 438 static void swap_pager_swapoff(struct swdevt *sp); 439 static void swap_pager_update_writecount(vm_object_t object, 440 vm_offset_t start, vm_offset_t end); 441 static void swap_pager_release_writecount(vm_object_t object, 442 vm_offset_t start, vm_offset_t end); 443 static void swap_pager_freespace_pgo(vm_object_t object, vm_pindex_t start, 444 vm_size_t size); 445 446 const struct pagerops swappagerops = { 447 .pgo_kvme_type = KVME_TYPE_SWAP, 448 .pgo_init = swap_pager_init, /* early system initialization of pager */ 449 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 450 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 451 .pgo_getpages = swap_pager_getpages, /* pagein */ 452 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 453 .pgo_putpages = swap_pager_putpages, /* pageout */ 454 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 455 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 456 .pgo_update_writecount = swap_pager_update_writecount, 457 .pgo_release_writecount = swap_pager_release_writecount, 458 .pgo_freespace = swap_pager_freespace_pgo, 459 }; 460 461 /* 462 * swap_*() routines are externally accessible. swp_*() routines are 463 * internal. 464 */ 465 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 466 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 467 468 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 469 "Maximum size of a swap block in pages"); 470 471 static void swp_sizecheck(void); 472 static void swp_pager_async_iodone(struct buf *bp); 473 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit); 474 static void swp_pager_free_empty_swblk(vm_object_t, struct swblk *sb); 475 static int swapongeom(struct vnode *); 476 static int swaponvp(struct thread *, struct vnode *, u_long); 477 static int swapoff_one(struct swdevt *sp, struct ucred *cred, 478 u_int flags); 479 480 /* 481 * Swap bitmap functions 482 */ 483 static void swp_pager_freeswapspace(const struct page_range *range); 484 static daddr_t swp_pager_getswapspace(int *npages); 485 486 /* 487 * Metadata functions 488 */ 489 static daddr_t swp_pager_meta_build(struct pctrie_iter *, vm_object_t object, 490 vm_pindex_t, daddr_t, bool); 491 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t, 492 vm_size_t *); 493 static void swp_pager_meta_transfer(vm_object_t src, vm_object_t dst, 494 vm_pindex_t pindex, vm_pindex_t count); 495 static void swp_pager_meta_free_all(vm_object_t); 496 static daddr_t swp_pager_meta_lookup(vm_object_t, vm_pindex_t); 497 498 static void 499 swp_pager_init_freerange(struct page_range *range) 500 { 501 range->start = SWAPBLK_NONE; 502 range->num = 0; 503 } 504 505 static void 506 swp_pager_update_freerange(struct page_range *range, daddr_t addr) 507 { 508 if (range->start + range->num == addr) { 509 range->num++; 510 } else { 511 swp_pager_freeswapspace(range); 512 range->start = addr; 513 range->num = 1; 514 } 515 } 516 517 static void * 518 swblk_trie_alloc(struct pctrie *ptree) 519 { 520 521 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? 522 M_USE_RESERVE : 0))); 523 } 524 525 static void 526 swblk_trie_free(struct pctrie *ptree, void *node) 527 { 528 529 uma_zfree(swpctrie_zone, node); 530 } 531 532 static int 533 swblk_start(struct swblk *sb, vm_pindex_t pindex) 534 { 535 return (sb == NULL || sb->p >= pindex ? 536 0 : pindex % SWAP_META_PAGES); 537 } 538 539 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); 540 541 static struct swblk * 542 swblk_lookup(vm_object_t object, vm_pindex_t pindex) 543 { 544 return (SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 545 rounddown(pindex, SWAP_META_PAGES))); 546 } 547 548 static void 549 swblk_lookup_remove(vm_object_t object, struct swblk *sb) 550 { 551 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 552 } 553 554 static bool 555 swblk_is_empty(vm_object_t object) 556 { 557 return (pctrie_is_empty(&object->un_pager.swp.swp_blks)); 558 } 559 560 static struct swblk * 561 swblk_iter_lookup_ge(struct pctrie_iter *blks, vm_pindex_t pindex) 562 { 563 return (SWAP_PCTRIE_ITER_LOOKUP_GE(blks, 564 rounddown(pindex, SWAP_META_PAGES))); 565 } 566 567 static void 568 swblk_iter_init_only(struct pctrie_iter *blks, vm_object_t object) 569 { 570 VM_OBJECT_ASSERT_LOCKED(object); 571 MPASS((object->flags & OBJ_SWAP) != 0); 572 pctrie_iter_init(blks, &object->un_pager.swp.swp_blks); 573 } 574 575 576 static struct swblk * 577 swblk_iter_init(struct pctrie_iter *blks, vm_object_t object, 578 vm_pindex_t pindex) 579 { 580 swblk_iter_init_only(blks, object); 581 return (swblk_iter_lookup_ge(blks, pindex)); 582 } 583 584 static struct swblk * 585 swblk_iter_reinit(struct pctrie_iter *blks, vm_object_t object, 586 vm_pindex_t pindex) 587 { 588 swblk_iter_init_only(blks, object); 589 return (SWAP_PCTRIE_ITER_LOOKUP(blks, 590 rounddown(pindex, SWAP_META_PAGES))); 591 } 592 593 static struct swblk * 594 swblk_iter_limit_init(struct pctrie_iter *blks, vm_object_t object, 595 vm_pindex_t pindex, vm_pindex_t limit) 596 { 597 VM_OBJECT_ASSERT_LOCKED(object); 598 MPASS((object->flags & OBJ_SWAP) != 0); 599 pctrie_iter_limit_init(blks, &object->un_pager.swp.swp_blks, limit); 600 return (swblk_iter_lookup_ge(blks, pindex)); 601 } 602 603 static struct swblk * 604 swblk_iter_next(struct pctrie_iter *blks) 605 { 606 return (SWAP_PCTRIE_ITER_JUMP_GE(blks, SWAP_META_PAGES)); 607 } 608 609 static struct swblk * 610 swblk_iter_lookup(struct pctrie_iter *blks, vm_pindex_t pindex) 611 { 612 return (SWAP_PCTRIE_ITER_LOOKUP(blks, 613 rounddown(pindex, SWAP_META_PAGES))); 614 } 615 616 static int 617 swblk_iter_insert(struct pctrie_iter *blks, struct swblk *sb) 618 { 619 return (SWAP_PCTRIE_ITER_INSERT(blks, sb)); 620 } 621 622 static void 623 swblk_iter_remove(struct pctrie_iter *blks) 624 { 625 SWAP_PCTRIE_ITER_REMOVE(blks); 626 } 627 628 /* 629 * SWP_SIZECHECK() - update swap_pager_full indication 630 * 631 * update the swap_pager_almost_full indication and warn when we are 632 * about to run out of swap space, using lowat/hiwat hysteresis. 633 * 634 * Clear swap_pager_full ( task killing ) indication when lowat is met. 635 * 636 * No restrictions on call 637 * This routine may not block. 638 */ 639 static void 640 swp_sizecheck(void) 641 { 642 643 if (swap_pager_avail < nswap_lowat) { 644 if (swap_pager_almost_full == 0) { 645 printf("swap_pager: out of swap space\n"); 646 swap_pager_almost_full = 1; 647 } 648 } else { 649 swap_pager_full = 0; 650 if (swap_pager_avail > nswap_hiwat) 651 swap_pager_almost_full = 0; 652 } 653 } 654 655 /* 656 * SWAP_PAGER_INIT() - initialize the swap pager! 657 * 658 * Expected to be started from system init. NOTE: This code is run 659 * before much else so be careful what you depend on. Most of the VM 660 * system has yet to be initialized at this point. 661 */ 662 static void 663 swap_pager_init(void) 664 { 665 /* 666 * Initialize object lists 667 */ 668 int i; 669 670 for (i = 0; i < NOBJLISTS; ++i) 671 TAILQ_INIT(&swap_pager_object_list[i]); 672 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 673 sx_init(&sw_alloc_sx, "swspsx"); 674 sx_init(&swdev_syscall_lock, "swsysc"); 675 676 /* 677 * The nsw_cluster_max is constrained by the bp->b_pages[] 678 * array, which has maxphys / PAGE_SIZE entries, and our locally 679 * defined MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 680 * constrained by the swap device interleave stripe size. 681 * 682 * Initialized early so that GEOM_ELI can see it. 683 */ 684 nsw_cluster_max = min(maxphys / PAGE_SIZE, MAX_PAGEOUT_CLUSTER); 685 } 686 687 /* 688 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 689 * 690 * Expected to be started from pageout process once, prior to entering 691 * its main loop. 692 */ 693 void 694 swap_pager_swap_init(void) 695 { 696 unsigned long n, n2; 697 698 /* 699 * Number of in-transit swap bp operations. Don't 700 * exhaust the pbufs completely. Make sure we 701 * initialize workable values (0 will work for hysteresis 702 * but it isn't very efficient). 703 * 704 * Currently we hardwire nsw_wcount_async to 4. This limit is 705 * designed to prevent other I/O from having high latencies due to 706 * our pageout I/O. The value 4 works well for one or two active swap 707 * devices but is probably a little low if you have more. Even so, 708 * a higher value would probably generate only a limited improvement 709 * with three or four active swap devices since the system does not 710 * typically have to pageout at extreme bandwidths. We will want 711 * at least 2 per swap devices, and 4 is a pretty good value if you 712 * have one NFS swap device due to the command/ack latency over NFS. 713 * So it all works out pretty well. 714 * 715 * nsw_cluster_max is initialized in swap_pager_init(). 716 */ 717 718 nsw_wcount_async = 4; 719 nsw_wcount_async_max = nsw_wcount_async; 720 mtx_init(&swbuf_mtx, "async swbuf mutex", NULL, MTX_DEF); 721 722 swwbuf_zone = pbuf_zsecond_create("swwbuf", nswbuf / 4); 723 swrbuf_zone = pbuf_zsecond_create("swrbuf", nswbuf / 2); 724 725 /* 726 * Initialize our zone, taking the user's requested size or 727 * estimating the number we need based on the number of pages 728 * in the system. 729 */ 730 n = maxswzone != 0 ? maxswzone / sizeof(struct swblk) : 731 vm_cnt.v_page_count / 2; 732 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, 733 pctrie_zone_init, NULL, UMA_ALIGN_PTR, 0); 734 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, 735 NULL, NULL, _Alignof(struct swblk) - 1, 0); 736 n2 = n; 737 do { 738 if (uma_zone_reserve_kva(swblk_zone, n)) 739 break; 740 /* 741 * if the allocation failed, try a zone two thirds the 742 * size of the previous attempt. 743 */ 744 n -= ((n + 2) / 3); 745 } while (n > 0); 746 747 /* 748 * Often uma_zone_reserve_kva() cannot reserve exactly the 749 * requested size. Account for the difference when 750 * calculating swap_maxpages. 751 */ 752 n = uma_zone_get_max(swblk_zone); 753 754 if (n < n2) 755 printf("Swap blk zone entries changed from %lu to %lu.\n", 756 n2, n); 757 /* absolute maximum we can handle assuming 100% efficiency */ 758 swap_maxpages = n * SWAP_META_PAGES; 759 swzone = n * sizeof(struct swblk); 760 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 761 printf("Cannot reserve swap pctrie zone, " 762 "reduce kern.maxswzone.\n"); 763 } 764 765 bool 766 swap_pager_init_object(vm_object_t object, void *handle, struct ucred *cred, 767 vm_ooffset_t size, vm_ooffset_t offset) 768 { 769 if (cred != NULL) { 770 if (!swap_reserve_by_cred(size, cred)) 771 return (false); 772 crhold(cred); 773 } 774 775 object->un_pager.swp.writemappings = 0; 776 object->handle = handle; 777 if (cred != NULL) { 778 object->cred = cred; 779 object->charge = size; 780 } 781 return (true); 782 } 783 784 static vm_object_t 785 swap_pager_alloc_init(objtype_t otype, void *handle, struct ucred *cred, 786 vm_ooffset_t size, vm_ooffset_t offset) 787 { 788 vm_object_t object; 789 790 /* 791 * The un_pager.swp.swp_blks trie is initialized by 792 * vm_object_allocate() to ensure the correct order of 793 * visibility to other threads. 794 */ 795 object = vm_object_allocate(otype, OFF_TO_IDX(offset + 796 PAGE_MASK + size)); 797 798 if (!swap_pager_init_object(object, handle, cred, size, offset)) { 799 vm_object_deallocate(object); 800 return (NULL); 801 } 802 return (object); 803 } 804 805 /* 806 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 807 * its metadata structures. 808 * 809 * This routine is called from the mmap and fork code to create a new 810 * OBJT_SWAP object. 811 * 812 * This routine must ensure that no live duplicate is created for 813 * the named object request, which is protected against by 814 * holding the sw_alloc_sx lock in case handle != NULL. 815 */ 816 static vm_object_t 817 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 818 vm_ooffset_t offset, struct ucred *cred) 819 { 820 vm_object_t object; 821 822 if (handle != NULL) { 823 /* 824 * Reference existing named region or allocate new one. There 825 * should not be a race here against swp_pager_meta_build() 826 * as called from vm_page_remove() in regards to the lookup 827 * of the handle. 828 */ 829 sx_xlock(&sw_alloc_sx); 830 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 831 if (object == NULL) { 832 object = swap_pager_alloc_init(OBJT_SWAP, handle, cred, 833 size, offset); 834 if (object != NULL) { 835 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 836 object, pager_object_list); 837 } 838 } 839 sx_xunlock(&sw_alloc_sx); 840 } else { 841 object = swap_pager_alloc_init(OBJT_SWAP, handle, cred, 842 size, offset); 843 } 844 return (object); 845 } 846 847 /* 848 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 849 * 850 * The swap backing for the object is destroyed. The code is 851 * designed such that we can reinstantiate it later, but this 852 * routine is typically called only when the entire object is 853 * about to be destroyed. 854 * 855 * The object must be locked. 856 */ 857 static void 858 swap_pager_dealloc(vm_object_t object) 859 { 860 861 VM_OBJECT_ASSERT_WLOCKED(object); 862 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 863 864 /* 865 * Remove from list right away so lookups will fail if we block for 866 * pageout completion. 867 */ 868 if ((object->flags & OBJ_ANON) == 0 && object->handle != NULL) { 869 VM_OBJECT_WUNLOCK(object); 870 sx_xlock(&sw_alloc_sx); 871 TAILQ_REMOVE(NOBJLIST(object->handle), object, 872 pager_object_list); 873 sx_xunlock(&sw_alloc_sx); 874 VM_OBJECT_WLOCK(object); 875 } 876 877 vm_object_pip_wait(object, "swpdea"); 878 879 /* 880 * Free all remaining metadata. We only bother to free it from 881 * the swap meta data. We do not attempt to free swapblk's still 882 * associated with vm_page_t's for this object. We do not care 883 * if paging is still in progress on some objects. 884 */ 885 swp_pager_meta_free_all(object); 886 object->handle = NULL; 887 object->type = OBJT_DEAD; 888 889 /* 890 * Release the allocation charge. 891 */ 892 if (object->cred != NULL) { 893 swap_release_by_cred(object->charge, object->cred); 894 object->charge = 0; 895 crfree(object->cred); 896 object->cred = NULL; 897 } 898 899 /* 900 * Hide the object from swap_pager_swapoff(). 901 */ 902 vm_object_clear_flag(object, OBJ_SWAP); 903 } 904 905 /************************************************************************ 906 * SWAP PAGER BITMAP ROUTINES * 907 ************************************************************************/ 908 909 /* 910 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 911 * 912 * Allocate swap for up to the requested number of pages. The 913 * starting swap block number (a page index) is returned or 914 * SWAPBLK_NONE if the allocation failed. 915 * 916 * Also has the side effect of advising that somebody made a mistake 917 * when they configured swap and didn't configure enough. 918 * 919 * This routine may not sleep. 920 * 921 * We allocate in round-robin fashion from the configured devices. 922 */ 923 static daddr_t 924 swp_pager_getswapspace(int *io_npages) 925 { 926 daddr_t blk; 927 struct swdevt *sp; 928 int mpages, npages; 929 930 KASSERT(*io_npages >= 1, 931 ("%s: npages not positive", __func__)); 932 blk = SWAPBLK_NONE; 933 mpages = *io_npages; 934 npages = imin(BLIST_MAX_ALLOC, mpages); 935 mtx_lock(&sw_dev_mtx); 936 sp = swdevhd; 937 while (!TAILQ_EMPTY(&swtailq)) { 938 if (sp == NULL) 939 sp = TAILQ_FIRST(&swtailq); 940 if ((sp->sw_flags & SW_CLOSING) == 0) 941 blk = blist_alloc(sp->sw_blist, &npages, mpages); 942 if (blk != SWAPBLK_NONE) 943 break; 944 sp = TAILQ_NEXT(sp, sw_list); 945 if (swdevhd == sp) { 946 if (npages == 1) 947 break; 948 mpages = npages - 1; 949 npages >>= 1; 950 } 951 } 952 if (blk != SWAPBLK_NONE) { 953 *io_npages = npages; 954 blk += sp->sw_first; 955 sp->sw_used += npages; 956 swap_pager_avail -= npages; 957 swp_sizecheck(); 958 swdevhd = TAILQ_NEXT(sp, sw_list); 959 } else { 960 if (swap_pager_full != 2) { 961 printf("swp_pager_getswapspace(%d): failed\n", 962 *io_npages); 963 swap_pager_full = 2; 964 swap_pager_almost_full = 1; 965 } 966 swdevhd = NULL; 967 } 968 mtx_unlock(&sw_dev_mtx); 969 return (blk); 970 } 971 972 static bool 973 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 974 { 975 976 return (blk >= sp->sw_first && blk < sp->sw_end); 977 } 978 979 static void 980 swp_pager_strategy(struct buf *bp) 981 { 982 struct swdevt *sp; 983 984 mtx_lock(&sw_dev_mtx); 985 TAILQ_FOREACH(sp, &swtailq, sw_list) { 986 if (swp_pager_isondev(bp->b_blkno, sp)) { 987 mtx_unlock(&sw_dev_mtx); 988 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 989 unmapped_buf_allowed) { 990 bp->b_data = unmapped_buf; 991 bp->b_offset = 0; 992 } else { 993 pmap_qenter((vm_offset_t)bp->b_data, 994 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 995 } 996 sp->sw_strategy(bp, sp); 997 return; 998 } 999 } 1000 panic("Swapdev not found"); 1001 } 1002 1003 /* 1004 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 1005 * 1006 * This routine returns the specified swap blocks back to the bitmap. 1007 * 1008 * This routine may not sleep. 1009 */ 1010 static void 1011 swp_pager_freeswapspace(const struct page_range *range) 1012 { 1013 daddr_t blk, npages; 1014 struct swdevt *sp; 1015 1016 blk = range->start; 1017 npages = range->num; 1018 if (npages == 0) 1019 return; 1020 mtx_lock(&sw_dev_mtx); 1021 TAILQ_FOREACH(sp, &swtailq, sw_list) { 1022 if (swp_pager_isondev(blk, sp)) { 1023 sp->sw_used -= npages; 1024 /* 1025 * If we are attempting to stop swapping on 1026 * this device, we don't want to mark any 1027 * blocks free lest they be reused. 1028 */ 1029 if ((sp->sw_flags & SW_CLOSING) == 0) { 1030 blist_free(sp->sw_blist, blk - sp->sw_first, 1031 npages); 1032 swap_pager_avail += npages; 1033 swp_sizecheck(); 1034 } 1035 mtx_unlock(&sw_dev_mtx); 1036 return; 1037 } 1038 } 1039 panic("Swapdev not found"); 1040 } 1041 1042 /* 1043 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 1044 */ 1045 static int 1046 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 1047 { 1048 struct sbuf sbuf; 1049 struct swdevt *sp; 1050 const char *devname; 1051 int error; 1052 1053 error = sysctl_wire_old_buffer(req, 0); 1054 if (error != 0) 1055 return (error); 1056 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 1057 mtx_lock(&sw_dev_mtx); 1058 TAILQ_FOREACH(sp, &swtailq, sw_list) { 1059 if (vn_isdisk(sp->sw_vp)) 1060 devname = devtoname(sp->sw_vp->v_rdev); 1061 else 1062 devname = "[file]"; 1063 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 1064 blist_stats(sp->sw_blist, &sbuf); 1065 } 1066 mtx_unlock(&sw_dev_mtx); 1067 error = sbuf_finish(&sbuf); 1068 sbuf_delete(&sbuf); 1069 return (error); 1070 } 1071 1072 /* 1073 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 1074 * range within an object. 1075 * 1076 * This routine removes swapblk assignments from swap metadata. 1077 * 1078 * The external callers of this routine typically have already destroyed 1079 * or renamed vm_page_t's associated with this range in the object so 1080 * we should be ok. 1081 * 1082 * The object must be locked. 1083 */ 1084 void 1085 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size, 1086 vm_size_t *freed) 1087 { 1088 MPASS((object->flags & OBJ_SWAP) != 0); 1089 1090 swp_pager_meta_free(object, start, size, freed); 1091 } 1092 1093 static void 1094 swap_pager_freespace_pgo(vm_object_t object, vm_pindex_t start, vm_size_t size) 1095 { 1096 MPASS((object->flags & OBJ_SWAP) != 0); 1097 1098 swp_pager_meta_free(object, start, size, NULL); 1099 } 1100 1101 /* 1102 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 1103 * 1104 * Assigns swap blocks to the specified range within the object. The 1105 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 1106 * 1107 * Returns 0 on success, -1 on failure. 1108 */ 1109 int 1110 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_pindex_t size) 1111 { 1112 struct pctrie_iter blks; 1113 struct page_range range; 1114 daddr_t addr, blk; 1115 vm_pindex_t i, j; 1116 int n; 1117 1118 swp_pager_init_freerange(&range); 1119 VM_OBJECT_WLOCK(object); 1120 swblk_iter_init_only(&blks, object); 1121 for (i = 0; i < size; i += n) { 1122 n = MIN(size - i, INT_MAX); 1123 blk = swp_pager_getswapspace(&n); 1124 if (blk == SWAPBLK_NONE) { 1125 swp_pager_meta_free(object, start, i, NULL); 1126 VM_OBJECT_WUNLOCK(object); 1127 return (-1); 1128 } 1129 for (j = 0; j < n; ++j) { 1130 addr = swp_pager_meta_build(&blks, object, 1131 start + i + j, blk + j, false); 1132 if (addr != SWAPBLK_NONE) 1133 swp_pager_update_freerange(&range, addr); 1134 } 1135 } 1136 swp_pager_freeswapspace(&range); 1137 VM_OBJECT_WUNLOCK(object); 1138 return (0); 1139 } 1140 1141 /* 1142 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 1143 * and destroy the source. 1144 * 1145 * Copy any valid swapblks from the source to the destination. In 1146 * cases where both the source and destination have a valid swapblk, 1147 * we keep the destination's. 1148 * 1149 * This routine is allowed to sleep. It may sleep allocating metadata 1150 * indirectly through swp_pager_meta_build(). 1151 * 1152 * The source object contains no vm_page_t's (which is just as well) 1153 * 1154 * The source and destination objects must be locked. 1155 * Both object locks may temporarily be released. 1156 */ 1157 void 1158 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 1159 vm_pindex_t offset, int destroysource) 1160 { 1161 VM_OBJECT_ASSERT_WLOCKED(srcobject); 1162 VM_OBJECT_ASSERT_WLOCKED(dstobject); 1163 1164 /* 1165 * If destroysource is set, we remove the source object from the 1166 * swap_pager internal queue now. 1167 */ 1168 if (destroysource && (srcobject->flags & OBJ_ANON) == 0 && 1169 srcobject->handle != NULL) { 1170 VM_OBJECT_WUNLOCK(srcobject); 1171 VM_OBJECT_WUNLOCK(dstobject); 1172 sx_xlock(&sw_alloc_sx); 1173 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 1174 pager_object_list); 1175 sx_xunlock(&sw_alloc_sx); 1176 VM_OBJECT_WLOCK(dstobject); 1177 VM_OBJECT_WLOCK(srcobject); 1178 } 1179 1180 /* 1181 * Transfer source to destination. 1182 */ 1183 swp_pager_meta_transfer(srcobject, dstobject, offset, dstobject->size); 1184 1185 /* 1186 * Free left over swap blocks in source. 1187 */ 1188 if (destroysource) 1189 swp_pager_meta_free_all(srcobject); 1190 } 1191 1192 /* 1193 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1194 * the requested page. 1195 * 1196 * We determine whether good backing store exists for the requested 1197 * page and return TRUE if it does, FALSE if it doesn't. 1198 * 1199 * If TRUE, we also try to determine how much valid, contiguous backing 1200 * store exists before and after the requested page. 1201 */ 1202 static boolean_t 1203 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1204 int *after) 1205 { 1206 daddr_t blk, blk0; 1207 int i; 1208 1209 VM_OBJECT_ASSERT_LOCKED(object); 1210 KASSERT((object->flags & OBJ_SWAP) != 0, 1211 ("%s: object not swappable", __func__)); 1212 1213 /* 1214 * do we have good backing store at the requested index ? 1215 */ 1216 blk0 = swp_pager_meta_lookup(object, pindex); 1217 if (blk0 == SWAPBLK_NONE) { 1218 if (before) 1219 *before = 0; 1220 if (after) 1221 *after = 0; 1222 return (FALSE); 1223 } 1224 1225 /* 1226 * find backwards-looking contiguous good backing store 1227 */ 1228 if (before != NULL) { 1229 for (i = 1; i < SWB_NPAGES; i++) { 1230 if (i > pindex) 1231 break; 1232 blk = swp_pager_meta_lookup(object, pindex - i); 1233 if (blk != blk0 - i) 1234 break; 1235 } 1236 *before = i - 1; 1237 } 1238 1239 /* 1240 * find forward-looking contiguous good backing store 1241 */ 1242 if (after != NULL) { 1243 for (i = 1; i < SWB_NPAGES; i++) { 1244 blk = swp_pager_meta_lookup(object, pindex + i); 1245 if (blk != blk0 + i) 1246 break; 1247 } 1248 *after = i - 1; 1249 } 1250 return (TRUE); 1251 } 1252 1253 static void 1254 swap_pager_unswapped_acct(vm_page_t m) 1255 { 1256 KASSERT((m->object->flags & OBJ_SWAP) != 0, 1257 ("Free object not swappable")); 1258 if ((m->a.flags & PGA_SWAP_FREE) != 0) 1259 counter_u64_add(swap_free_completed, 1); 1260 vm_page_aflag_clear(m, PGA_SWAP_FREE | PGA_SWAP_SPACE); 1261 1262 /* 1263 * The meta data only exists if the object is OBJT_SWAP 1264 * and even then might not be allocated yet. 1265 */ 1266 } 1267 1268 /* 1269 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1270 * 1271 * This removes any associated swap backing store, whether valid or 1272 * not, from the page. 1273 * 1274 * This routine is typically called when a page is made dirty, at 1275 * which point any associated swap can be freed. MADV_FREE also 1276 * calls us in a special-case situation 1277 * 1278 * NOTE!!! If the page is clean and the swap was valid, the caller 1279 * should make the page dirty before calling this routine. This routine 1280 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1281 * depends on it. 1282 * 1283 * This routine may not sleep. 1284 * 1285 * The object containing the page may be locked. 1286 */ 1287 static void 1288 swap_pager_unswapped(vm_page_t m) 1289 { 1290 struct page_range range; 1291 struct swblk *sb; 1292 vm_object_t obj; 1293 1294 /* 1295 * Handle enqueing deferred frees first. If we do not have the 1296 * object lock we wait for the page daemon to clear the space. 1297 */ 1298 obj = m->object; 1299 if (!VM_OBJECT_WOWNED(obj)) { 1300 VM_PAGE_OBJECT_BUSY_ASSERT(m); 1301 /* 1302 * The caller is responsible for synchronization but we 1303 * will harmlessly handle races. This is typically provided 1304 * by only calling unswapped() when a page transitions from 1305 * clean to dirty. 1306 */ 1307 if ((m->a.flags & (PGA_SWAP_SPACE | PGA_SWAP_FREE)) == 1308 PGA_SWAP_SPACE) { 1309 vm_page_aflag_set(m, PGA_SWAP_FREE); 1310 counter_u64_add(swap_free_deferred, 1); 1311 } 1312 return; 1313 } 1314 swap_pager_unswapped_acct(m); 1315 1316 sb = swblk_lookup(m->object, m->pindex); 1317 if (sb == NULL) 1318 return; 1319 range.start = sb->d[m->pindex % SWAP_META_PAGES]; 1320 if (range.start == SWAPBLK_NONE) 1321 return; 1322 range.num = 1; 1323 swp_pager_freeswapspace(&range); 1324 sb->d[m->pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 1325 swp_pager_free_empty_swblk(m->object, sb); 1326 } 1327 1328 /* 1329 * swap_pager_getpages() - bring pages in from swap 1330 * 1331 * Attempt to page in the pages in array "ma" of length "count". The 1332 * caller may optionally specify that additional pages preceding and 1333 * succeeding the specified range be paged in. The number of such pages 1334 * is returned in the "rbehind" and "rahead" parameters, and they will 1335 * be in the inactive queue upon return. 1336 * 1337 * The pages in "ma" must be busied and will remain busied upon return. 1338 */ 1339 static int 1340 swap_pager_getpages_locked(vm_object_t object, vm_page_t *ma, int count, 1341 int *rbehind, int *rahead) 1342 { 1343 struct buf *bp; 1344 vm_page_t bm, mpred, msucc, p; 1345 vm_pindex_t pindex; 1346 daddr_t blk; 1347 int i, maxahead, maxbehind, reqcount; 1348 1349 VM_OBJECT_ASSERT_WLOCKED(object); 1350 reqcount = count; 1351 1352 KASSERT((object->flags & OBJ_SWAP) != 0, 1353 ("%s: object not swappable", __func__)); 1354 if (!swap_pager_haspage(object, ma[0]->pindex, &maxbehind, &maxahead)) { 1355 VM_OBJECT_WUNLOCK(object); 1356 return (VM_PAGER_FAIL); 1357 } 1358 1359 KASSERT(reqcount - 1 <= maxahead, 1360 ("page count %d extends beyond swap block", reqcount)); 1361 1362 /* 1363 * Do not transfer any pages other than those that are xbusied 1364 * when running during a split or collapse operation. This 1365 * prevents clustering from re-creating pages which are being 1366 * moved into another object. 1367 */ 1368 if ((object->flags & (OBJ_SPLIT | OBJ_DEAD)) != 0) { 1369 maxahead = reqcount - 1; 1370 maxbehind = 0; 1371 } 1372 1373 /* 1374 * Clip the readahead and readbehind ranges to exclude resident pages. 1375 */ 1376 if (rahead != NULL) { 1377 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1378 pindex = ma[reqcount - 1]->pindex; 1379 msucc = TAILQ_NEXT(ma[reqcount - 1], listq); 1380 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1381 *rahead = msucc->pindex - pindex - 1; 1382 } 1383 if (rbehind != NULL) { 1384 *rbehind = imin(*rbehind, maxbehind); 1385 pindex = ma[0]->pindex; 1386 mpred = TAILQ_PREV(ma[0], pglist, listq); 1387 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1388 *rbehind = pindex - mpred->pindex - 1; 1389 } 1390 1391 bm = ma[0]; 1392 for (i = 0; i < count; i++) 1393 ma[i]->oflags |= VPO_SWAPINPROG; 1394 1395 /* 1396 * Allocate readahead and readbehind pages. 1397 */ 1398 if (rbehind != NULL) { 1399 for (i = 1; i <= *rbehind; i++) { 1400 p = vm_page_alloc(object, ma[0]->pindex - i, 1401 VM_ALLOC_NORMAL); 1402 if (p == NULL) 1403 break; 1404 p->oflags |= VPO_SWAPINPROG; 1405 bm = p; 1406 } 1407 *rbehind = i - 1; 1408 } 1409 if (rahead != NULL) { 1410 for (i = 0; i < *rahead; i++) { 1411 p = vm_page_alloc(object, 1412 ma[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1413 if (p == NULL) 1414 break; 1415 p->oflags |= VPO_SWAPINPROG; 1416 } 1417 *rahead = i; 1418 } 1419 if (rbehind != NULL) 1420 count += *rbehind; 1421 if (rahead != NULL) 1422 count += *rahead; 1423 1424 vm_object_pip_add(object, count); 1425 1426 pindex = bm->pindex; 1427 blk = swp_pager_meta_lookup(object, pindex); 1428 KASSERT(blk != SWAPBLK_NONE, 1429 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1430 1431 VM_OBJECT_WUNLOCK(object); 1432 bp = uma_zalloc(swrbuf_zone, M_WAITOK); 1433 MPASS((bp->b_flags & B_MAXPHYS) != 0); 1434 /* Pages cannot leave the object while busy. */ 1435 for (i = 0, p = bm; i < count; i++, p = TAILQ_NEXT(p, listq)) { 1436 MPASS(p->pindex == bm->pindex + i); 1437 bp->b_pages[i] = p; 1438 } 1439 1440 bp->b_flags |= B_PAGING; 1441 bp->b_iocmd = BIO_READ; 1442 bp->b_iodone = swp_pager_async_iodone; 1443 bp->b_rcred = crhold(thread0.td_ucred); 1444 bp->b_wcred = crhold(thread0.td_ucred); 1445 bp->b_blkno = blk; 1446 bp->b_bcount = PAGE_SIZE * count; 1447 bp->b_bufsize = PAGE_SIZE * count; 1448 bp->b_npages = count; 1449 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1450 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1451 1452 VM_CNT_INC(v_swapin); 1453 VM_CNT_ADD(v_swappgsin, count); 1454 1455 /* 1456 * perform the I/O. NOTE!!! bp cannot be considered valid after 1457 * this point because we automatically release it on completion. 1458 * Instead, we look at the one page we are interested in which we 1459 * still hold a lock on even through the I/O completion. 1460 * 1461 * The other pages in our ma[] array are also released on completion, 1462 * so we cannot assume they are valid anymore either. 1463 * 1464 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1465 */ 1466 BUF_KERNPROC(bp); 1467 swp_pager_strategy(bp); 1468 1469 /* 1470 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1471 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1472 * is set in the metadata for each page in the request. 1473 */ 1474 VM_OBJECT_WLOCK(object); 1475 /* This could be implemented more efficiently with aflags */ 1476 while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) { 1477 ma[0]->oflags |= VPO_SWAPSLEEP; 1478 VM_CNT_INC(v_intrans); 1479 if (VM_OBJECT_SLEEP(object, &object->handle, PSWP, 1480 "swread", hz * 20)) { 1481 printf( 1482 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1483 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1484 } 1485 } 1486 VM_OBJECT_WUNLOCK(object); 1487 1488 /* 1489 * If we had an unrecoverable read error pages will not be valid. 1490 */ 1491 for (i = 0; i < reqcount; i++) 1492 if (ma[i]->valid != VM_PAGE_BITS_ALL) 1493 return (VM_PAGER_ERROR); 1494 1495 return (VM_PAGER_OK); 1496 1497 /* 1498 * A final note: in a low swap situation, we cannot deallocate swap 1499 * and mark a page dirty here because the caller is likely to mark 1500 * the page clean when we return, causing the page to possibly revert 1501 * to all-zero's later. 1502 */ 1503 } 1504 1505 static int 1506 swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count, 1507 int *rbehind, int *rahead) 1508 { 1509 1510 VM_OBJECT_WLOCK(object); 1511 return (swap_pager_getpages_locked(object, ma, count, rbehind, rahead)); 1512 } 1513 1514 /* 1515 * swap_pager_getpages_async(): 1516 * 1517 * Right now this is emulation of asynchronous operation on top of 1518 * swap_pager_getpages(). 1519 */ 1520 static int 1521 swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count, 1522 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1523 { 1524 int r, error; 1525 1526 r = swap_pager_getpages(object, ma, count, rbehind, rahead); 1527 switch (r) { 1528 case VM_PAGER_OK: 1529 error = 0; 1530 break; 1531 case VM_PAGER_ERROR: 1532 error = EIO; 1533 break; 1534 case VM_PAGER_FAIL: 1535 error = EINVAL; 1536 break; 1537 default: 1538 panic("unhandled swap_pager_getpages() error %d", r); 1539 } 1540 (iodone)(arg, ma, count, error); 1541 1542 return (r); 1543 } 1544 1545 /* 1546 * swap_pager_putpages: 1547 * 1548 * Assign swap (if necessary) and initiate I/O on the specified pages. 1549 * 1550 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1551 * vm_page reservation system coupled with properly written VFS devices 1552 * should ensure that no low-memory deadlock occurs. This is an area 1553 * which needs work. 1554 * 1555 * The parent has N vm_object_pip_add() references prior to 1556 * calling us and will remove references for rtvals[] that are 1557 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1558 * completion. 1559 * 1560 * The parent has soft-busy'd the pages it passes us and will unbusy 1561 * those whose rtvals[] entry is not set to VM_PAGER_PEND on return. 1562 * We need to unbusy the rest on I/O completion. 1563 */ 1564 static void 1565 swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count, 1566 int flags, int *rtvals) 1567 { 1568 struct pctrie_iter blks; 1569 struct page_range range; 1570 struct buf *bp; 1571 daddr_t addr, blk; 1572 vm_page_t mreq; 1573 int i, j, n; 1574 bool async; 1575 1576 KASSERT(count == 0 || ma[0]->object == object, 1577 ("%s: object mismatch %p/%p", 1578 __func__, object, ma[0]->object)); 1579 1580 VM_OBJECT_WUNLOCK(object); 1581 async = curproc == pageproc && (flags & VM_PAGER_PUT_SYNC) == 0; 1582 swp_pager_init_freerange(&range); 1583 1584 /* 1585 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1586 * The page is left dirty until the pageout operation completes 1587 * successfully. 1588 */ 1589 for (i = 0; i < count; i += n) { 1590 /* Maximum I/O size is limited by maximum swap block size. */ 1591 n = min(count - i, nsw_cluster_max); 1592 1593 if (async) { 1594 mtx_lock(&swbuf_mtx); 1595 while (nsw_wcount_async == 0) 1596 msleep(&nsw_wcount_async, &swbuf_mtx, PVM, 1597 "swbufa", 0); 1598 nsw_wcount_async--; 1599 mtx_unlock(&swbuf_mtx); 1600 } 1601 1602 /* Get a block of swap of size up to size n. */ 1603 blk = swp_pager_getswapspace(&n); 1604 if (blk == SWAPBLK_NONE) { 1605 mtx_lock(&swbuf_mtx); 1606 if (++nsw_wcount_async == 1) 1607 wakeup(&nsw_wcount_async); 1608 mtx_unlock(&swbuf_mtx); 1609 for (j = 0; j < n; ++j) 1610 rtvals[i + j] = VM_PAGER_FAIL; 1611 continue; 1612 } 1613 VM_OBJECT_WLOCK(object); 1614 swblk_iter_init_only(&blks, object); 1615 for (j = 0; j < n; ++j) { 1616 mreq = ma[i + j]; 1617 vm_page_aflag_clear(mreq, PGA_SWAP_FREE); 1618 KASSERT(mreq->object == object, 1619 ("%s: object mismatch %p/%p", 1620 __func__, mreq->object, object)); 1621 addr = swp_pager_meta_build(&blks, object, 1622 mreq->pindex, blk + j, false); 1623 if (addr != SWAPBLK_NONE) 1624 swp_pager_update_freerange(&range, addr); 1625 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1626 mreq->oflags |= VPO_SWAPINPROG; 1627 } 1628 VM_OBJECT_WUNLOCK(object); 1629 1630 bp = uma_zalloc(swwbuf_zone, M_WAITOK); 1631 MPASS((bp->b_flags & B_MAXPHYS) != 0); 1632 if (async) 1633 bp->b_flags |= B_ASYNC; 1634 bp->b_flags |= B_PAGING; 1635 bp->b_iocmd = BIO_WRITE; 1636 1637 bp->b_rcred = crhold(thread0.td_ucred); 1638 bp->b_wcred = crhold(thread0.td_ucred); 1639 bp->b_bcount = PAGE_SIZE * n; 1640 bp->b_bufsize = PAGE_SIZE * n; 1641 bp->b_blkno = blk; 1642 for (j = 0; j < n; j++) 1643 bp->b_pages[j] = ma[i + j]; 1644 bp->b_npages = n; 1645 1646 /* 1647 * Must set dirty range for NFS to work. 1648 */ 1649 bp->b_dirtyoff = 0; 1650 bp->b_dirtyend = bp->b_bcount; 1651 1652 VM_CNT_INC(v_swapout); 1653 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1654 1655 /* 1656 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1657 * can call the async completion routine at the end of a 1658 * synchronous I/O operation. Otherwise, our caller would 1659 * perform duplicate unbusy and wakeup operations on the page 1660 * and object, respectively. 1661 */ 1662 for (j = 0; j < n; j++) 1663 rtvals[i + j] = VM_PAGER_PEND; 1664 1665 /* 1666 * asynchronous 1667 * 1668 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1669 */ 1670 if (async) { 1671 bp->b_iodone = swp_pager_async_iodone; 1672 BUF_KERNPROC(bp); 1673 swp_pager_strategy(bp); 1674 continue; 1675 } 1676 1677 /* 1678 * synchronous 1679 * 1680 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1681 */ 1682 bp->b_iodone = bdone; 1683 swp_pager_strategy(bp); 1684 1685 /* 1686 * Wait for the sync I/O to complete. 1687 */ 1688 bwait(bp, PVM, "swwrt"); 1689 1690 /* 1691 * Now that we are through with the bp, we can call the 1692 * normal async completion, which frees everything up. 1693 */ 1694 swp_pager_async_iodone(bp); 1695 } 1696 swp_pager_freeswapspace(&range); 1697 VM_OBJECT_WLOCK(object); 1698 } 1699 1700 /* 1701 * swp_pager_async_iodone: 1702 * 1703 * Completion routine for asynchronous reads and writes from/to swap. 1704 * Also called manually by synchronous code to finish up a bp. 1705 * 1706 * This routine may not sleep. 1707 */ 1708 static void 1709 swp_pager_async_iodone(struct buf *bp) 1710 { 1711 int i; 1712 vm_object_t object = NULL; 1713 1714 /* 1715 * Report error - unless we ran out of memory, in which case 1716 * we've already logged it in swapgeom_strategy(). 1717 */ 1718 if (bp->b_ioflags & BIO_ERROR && bp->b_error != ENOMEM) { 1719 printf( 1720 "swap_pager: I/O error - %s failed; blkno %ld," 1721 "size %ld, error %d\n", 1722 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1723 (long)bp->b_blkno, 1724 (long)bp->b_bcount, 1725 bp->b_error 1726 ); 1727 } 1728 1729 /* 1730 * remove the mapping for kernel virtual 1731 */ 1732 if (buf_mapped(bp)) 1733 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1734 else 1735 bp->b_data = bp->b_kvabase; 1736 1737 if (bp->b_npages) { 1738 object = bp->b_pages[0]->object; 1739 VM_OBJECT_WLOCK(object); 1740 } 1741 1742 /* 1743 * cleanup pages. If an error occurs writing to swap, we are in 1744 * very serious trouble. If it happens to be a disk error, though, 1745 * we may be able to recover by reassigning the swap later on. So 1746 * in this case we remove the m->swapblk assignment for the page 1747 * but do not free it in the rlist. The errornous block(s) are thus 1748 * never reallocated as swap. Redirty the page and continue. 1749 */ 1750 for (i = 0; i < bp->b_npages; ++i) { 1751 vm_page_t m = bp->b_pages[i]; 1752 1753 m->oflags &= ~VPO_SWAPINPROG; 1754 if (m->oflags & VPO_SWAPSLEEP) { 1755 m->oflags &= ~VPO_SWAPSLEEP; 1756 wakeup(&object->handle); 1757 } 1758 1759 /* We always have space after I/O, successful or not. */ 1760 vm_page_aflag_set(m, PGA_SWAP_SPACE); 1761 1762 if (bp->b_ioflags & BIO_ERROR) { 1763 /* 1764 * If an error occurs I'd love to throw the swapblk 1765 * away without freeing it back to swapspace, so it 1766 * can never be used again. But I can't from an 1767 * interrupt. 1768 */ 1769 if (bp->b_iocmd == BIO_READ) { 1770 /* 1771 * NOTE: for reads, m->dirty will probably 1772 * be overridden by the original caller of 1773 * getpages so don't play cute tricks here. 1774 */ 1775 vm_page_invalid(m); 1776 if (i < bp->b_pgbefore || 1777 i >= bp->b_npages - bp->b_pgafter) 1778 vm_page_free_invalid(m); 1779 } else { 1780 /* 1781 * If a write error occurs, reactivate page 1782 * so it doesn't clog the inactive list, 1783 * then finish the I/O. 1784 */ 1785 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1786 1787 /* PQ_UNSWAPPABLE? */ 1788 vm_page_activate(m); 1789 vm_page_sunbusy(m); 1790 } 1791 } else if (bp->b_iocmd == BIO_READ) { 1792 /* 1793 * NOTE: for reads, m->dirty will probably be 1794 * overridden by the original caller of getpages so 1795 * we cannot set them in order to free the underlying 1796 * swap in a low-swap situation. I don't think we'd 1797 * want to do that anyway, but it was an optimization 1798 * that existed in the old swapper for a time before 1799 * it got ripped out due to precisely this problem. 1800 */ 1801 KASSERT(!pmap_page_is_mapped(m), 1802 ("swp_pager_async_iodone: page %p is mapped", m)); 1803 KASSERT(m->dirty == 0, 1804 ("swp_pager_async_iodone: page %p is dirty", m)); 1805 1806 vm_page_valid(m); 1807 if (i < bp->b_pgbefore || 1808 i >= bp->b_npages - bp->b_pgafter) 1809 vm_page_readahead_finish(m); 1810 } else { 1811 /* 1812 * For write success, clear the dirty 1813 * status, then finish the I/O ( which decrements the 1814 * busy count and possibly wakes waiter's up ). 1815 * A page is only written to swap after a period of 1816 * inactivity. Therefore, we do not expect it to be 1817 * reused. 1818 */ 1819 KASSERT(!pmap_page_is_write_mapped(m), 1820 ("swp_pager_async_iodone: page %p is not write" 1821 " protected", m)); 1822 vm_page_undirty(m); 1823 vm_page_deactivate_noreuse(m); 1824 vm_page_sunbusy(m); 1825 } 1826 } 1827 1828 /* 1829 * adjust pip. NOTE: the original parent may still have its own 1830 * pip refs on the object. 1831 */ 1832 if (object != NULL) { 1833 vm_object_pip_wakeupn(object, bp->b_npages); 1834 VM_OBJECT_WUNLOCK(object); 1835 } 1836 1837 /* 1838 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1839 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1840 * trigger a KASSERT in relpbuf(). 1841 */ 1842 if (bp->b_vp) { 1843 bp->b_vp = NULL; 1844 bp->b_bufobj = NULL; 1845 } 1846 /* 1847 * release the physical I/O buffer 1848 */ 1849 if (bp->b_flags & B_ASYNC) { 1850 mtx_lock(&swbuf_mtx); 1851 if (++nsw_wcount_async == 1) 1852 wakeup(&nsw_wcount_async); 1853 mtx_unlock(&swbuf_mtx); 1854 } 1855 uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp); 1856 } 1857 1858 int 1859 swap_pager_nswapdev(void) 1860 { 1861 1862 return (nswapdev); 1863 } 1864 1865 static void 1866 swp_pager_force_dirty(struct page_range *range, vm_page_t m, daddr_t *blk) 1867 { 1868 vm_page_dirty(m); 1869 swap_pager_unswapped_acct(m); 1870 swp_pager_update_freerange(range, *blk); 1871 *blk = SWAPBLK_NONE; 1872 vm_page_launder(m); 1873 } 1874 1875 u_long 1876 swap_pager_swapped_pages(vm_object_t object) 1877 { 1878 struct pctrie_iter blks; 1879 struct swblk *sb; 1880 u_long res; 1881 int i; 1882 1883 VM_OBJECT_ASSERT_LOCKED(object); 1884 1885 if (swblk_is_empty(object)) 1886 return (0); 1887 1888 res = 0; 1889 for (sb = swblk_iter_init(&blks, object, 0); sb != NULL; 1890 sb = swblk_iter_next(&blks)) { 1891 for (i = 0; i < SWAP_META_PAGES; i++) { 1892 if (sb->d[i] != SWAPBLK_NONE) 1893 res++; 1894 } 1895 } 1896 return (res); 1897 } 1898 1899 /* 1900 * swap_pager_swapoff_object: 1901 * 1902 * Page in all of the pages that have been paged out for an object 1903 * to a swap device. 1904 */ 1905 static void 1906 swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object) 1907 { 1908 struct pctrie_iter blks, pages; 1909 struct page_range range; 1910 struct swblk *sb; 1911 vm_page_t m; 1912 int i, rahead, rv; 1913 bool sb_empty; 1914 1915 VM_OBJECT_ASSERT_WLOCKED(object); 1916 KASSERT((object->flags & OBJ_SWAP) != 0, 1917 ("%s: Object not swappable", __func__)); 1918 KASSERT((object->flags & OBJ_DEAD) == 0, 1919 ("%s: Object already dead", __func__)); 1920 KASSERT((sp->sw_flags & SW_CLOSING) != 0, 1921 ("%s: Device not blocking further allocations", __func__)); 1922 1923 vm_page_iter_init(&pages, object); 1924 swp_pager_init_freerange(&range); 1925 sb = swblk_iter_init(&blks, object, 0); 1926 while (sb != NULL) { 1927 sb_empty = true; 1928 for (i = 0; i < SWAP_META_PAGES; i++) { 1929 /* Skip an invalid block. */ 1930 if (sb->d[i] == SWAPBLK_NONE) 1931 continue; 1932 /* Skip a block not of this device. */ 1933 if (!swp_pager_isondev(sb->d[i], sp)) { 1934 sb_empty = false; 1935 continue; 1936 } 1937 1938 /* 1939 * Look for a page corresponding to this block. If the 1940 * found page has pending operations, sleep and restart 1941 * the scan. 1942 */ 1943 m = vm_page_iter_lookup(&pages, blks.index + i); 1944 if (m != NULL && (m->oflags & VPO_SWAPINPROG) != 0) { 1945 m->oflags |= VPO_SWAPSLEEP; 1946 VM_OBJECT_SLEEP(object, &object->handle, PSWP, 1947 "swpoff", 0); 1948 break; 1949 } 1950 1951 /* 1952 * If the found page is valid, mark it dirty and free 1953 * the swap block. 1954 */ 1955 if (m != NULL && vm_page_all_valid(m)) { 1956 swp_pager_force_dirty(&range, m, &sb->d[i]); 1957 continue; 1958 } 1959 /* Is there a page we can acquire or allocate? */ 1960 if (m != NULL) { 1961 if (!vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL)) 1962 break; 1963 } else if ((m = vm_page_alloc(object, blks.index + i, 1964 VM_ALLOC_NORMAL | VM_ALLOC_WAITFAIL)) == NULL) 1965 break; 1966 1967 /* Get the page from swap, and restart the scan. */ 1968 vm_object_pip_add(object, 1); 1969 rahead = SWAP_META_PAGES; 1970 rv = swap_pager_getpages_locked(object, &m, 1, 1971 NULL, &rahead); 1972 if (rv != VM_PAGER_OK) 1973 panic("%s: read from swap failed: %d", 1974 __func__, rv); 1975 VM_OBJECT_WLOCK(object); 1976 vm_object_pip_wakeupn(object, 1); 1977 KASSERT(vm_page_all_valid(m), 1978 ("%s: Page %p not all valid", __func__, m)); 1979 vm_page_xunbusy(m); 1980 break; 1981 } 1982 if (i < SWAP_META_PAGES) { 1983 /* 1984 * The object lock has been released and regained. 1985 * Perhaps the object is now dead. 1986 */ 1987 if ((object->flags & OBJ_DEAD) != 0) { 1988 /* 1989 * Make sure that pending writes finish before 1990 * returning. 1991 */ 1992 vm_object_pip_wait(object, "swpoff"); 1993 swp_pager_meta_free_all(object); 1994 break; 1995 } 1996 1997 /* 1998 * The swapblk could have been freed, so reset the pages 1999 * iterator and search again for the first swblk at or 2000 * after blks.index. 2001 */ 2002 pctrie_iter_reset(&pages); 2003 sb = swblk_iter_init(&blks, object, blks.index); 2004 continue; 2005 } 2006 if (sb_empty) { 2007 swblk_iter_remove(&blks); 2008 uma_zfree(swblk_zone, sb); 2009 } 2010 2011 /* 2012 * It is safe to advance to the next block. No allocations 2013 * before blk.index have happened, even with the lock released, 2014 * because allocations on this device are blocked. 2015 */ 2016 sb = swblk_iter_next(&blks); 2017 } 2018 swp_pager_freeswapspace(&range); 2019 } 2020 2021 /* 2022 * swap_pager_swapoff: 2023 * 2024 * Page in all of the pages that have been paged out to the 2025 * given device. The corresponding blocks in the bitmap must be 2026 * marked as allocated and the device must be flagged SW_CLOSING. 2027 * There may be no processes swapped out to the device. 2028 * 2029 * This routine may block. 2030 */ 2031 static void 2032 swap_pager_swapoff(struct swdevt *sp) 2033 { 2034 vm_object_t object; 2035 int retries; 2036 2037 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2038 2039 retries = 0; 2040 full_rescan: 2041 mtx_lock(&vm_object_list_mtx); 2042 TAILQ_FOREACH(object, &vm_object_list, object_list) { 2043 if ((object->flags & OBJ_SWAP) == 0) 2044 continue; 2045 mtx_unlock(&vm_object_list_mtx); 2046 /* Depends on type-stability. */ 2047 VM_OBJECT_WLOCK(object); 2048 2049 /* 2050 * Dead objects are eventually terminated on their own. 2051 */ 2052 if ((object->flags & OBJ_DEAD) != 0) 2053 goto next_obj; 2054 2055 /* 2056 * Sync with fences placed after pctrie 2057 * initialization. We must not access pctrie below 2058 * unless we checked that our object is swap and not 2059 * dead. 2060 */ 2061 atomic_thread_fence_acq(); 2062 if ((object->flags & OBJ_SWAP) == 0) 2063 goto next_obj; 2064 2065 swap_pager_swapoff_object(sp, object); 2066 next_obj: 2067 VM_OBJECT_WUNLOCK(object); 2068 mtx_lock(&vm_object_list_mtx); 2069 } 2070 mtx_unlock(&vm_object_list_mtx); 2071 2072 if (sp->sw_used) { 2073 /* 2074 * Objects may be locked or paging to the device being 2075 * removed, so we will miss their pages and need to 2076 * make another pass. We have marked this device as 2077 * SW_CLOSING, so the activity should finish soon. 2078 */ 2079 retries++; 2080 if (retries > 100) { 2081 panic("swapoff: failed to locate %d swap blocks", 2082 sp->sw_used); 2083 } 2084 pause("swpoff", hz / 20); 2085 goto full_rescan; 2086 } 2087 EVENTHANDLER_INVOKE(swapoff, sp); 2088 } 2089 2090 /************************************************************************ 2091 * SWAP META DATA * 2092 ************************************************************************ 2093 * 2094 * These routines manipulate the swap metadata stored in the 2095 * OBJT_SWAP object. 2096 * 2097 * Swap metadata is implemented with a global hash and not directly 2098 * linked into the object. Instead the object simply contains 2099 * appropriate tracking counters. 2100 */ 2101 2102 /* 2103 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? 2104 */ 2105 static bool 2106 swp_pager_swblk_empty(struct swblk *sb, int start, int limit) 2107 { 2108 int i; 2109 2110 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); 2111 for (i = start; i < limit; i++) { 2112 if (sb->d[i] != SWAPBLK_NONE) 2113 return (false); 2114 } 2115 return (true); 2116 } 2117 2118 /* 2119 * SWP_PAGER_FREE_EMPTY_SWBLK() - frees if a block is free 2120 * 2121 * Nothing is done if the block is still in use. 2122 */ 2123 static void 2124 swp_pager_free_empty_swblk(vm_object_t object, struct swblk *sb) 2125 { 2126 2127 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 2128 swblk_lookup_remove(object, sb); 2129 uma_zfree(swblk_zone, sb); 2130 } 2131 } 2132 2133 /* 2134 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 2135 * 2136 * Try to add the specified swapblk to the object's swap metadata. If 2137 * nowait_noreplace is set, add the specified swapblk only if there is no 2138 * previously assigned swapblk at pindex. If the swapblk is invalid, and 2139 * replaces a valid swapblk, empty swap metadata is freed. If memory 2140 * allocation fails, and nowait_noreplace is set, return the specified 2141 * swapblk immediately to indicate failure; otherwise, wait and retry until 2142 * memory allocation succeeds. Return the previously assigned swapblk, if 2143 * any. 2144 */ 2145 static daddr_t 2146 swp_pager_meta_build(struct pctrie_iter *blks, vm_object_t object, 2147 vm_pindex_t pindex, daddr_t swapblk, bool nowait_noreplace) 2148 { 2149 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 2150 struct swblk *sb, *sb1; 2151 vm_pindex_t modpi; 2152 daddr_t prev_swapblk; 2153 int error, i; 2154 2155 VM_OBJECT_ASSERT_WLOCKED(object); 2156 2157 sb = swblk_iter_lookup(blks, pindex); 2158 if (sb == NULL) { 2159 if (swapblk == SWAPBLK_NONE) 2160 return (SWAPBLK_NONE); 2161 for (;;) { 2162 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 2163 pageproc ? M_USE_RESERVE : 0)); 2164 if (sb != NULL) { 2165 sb->p = rounddown(pindex, SWAP_META_PAGES); 2166 for (i = 0; i < SWAP_META_PAGES; i++) 2167 sb->d[i] = SWAPBLK_NONE; 2168 if (atomic_cmpset_int(&swblk_zone_exhausted, 2169 1, 0)) 2170 printf("swblk zone ok\n"); 2171 break; 2172 } 2173 if (nowait_noreplace) 2174 return (swapblk); 2175 VM_OBJECT_WUNLOCK(object); 2176 if (uma_zone_exhausted(swblk_zone)) { 2177 if (atomic_cmpset_int(&swblk_zone_exhausted, 2178 0, 1)) 2179 printf("swap blk zone exhausted, " 2180 "increase kern.maxswzone\n"); 2181 vm_pageout_oom(VM_OOM_SWAPZ); 2182 pause("swzonxb", 10); 2183 } else 2184 uma_zwait(swblk_zone); 2185 VM_OBJECT_WLOCK(object); 2186 sb = swblk_iter_reinit(blks, object, pindex); 2187 if (sb != NULL) 2188 /* 2189 * Somebody swapped out a nearby page, 2190 * allocating swblk at the pindex index, 2191 * while we dropped the object lock. 2192 */ 2193 goto allocated; 2194 } 2195 for (;;) { 2196 error = swblk_iter_insert(blks, sb); 2197 if (error == 0) { 2198 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2199 1, 0)) 2200 printf("swpctrie zone ok\n"); 2201 break; 2202 } 2203 if (nowait_noreplace) { 2204 uma_zfree(swblk_zone, sb); 2205 return (swapblk); 2206 } 2207 VM_OBJECT_WUNLOCK(object); 2208 if (uma_zone_exhausted(swpctrie_zone)) { 2209 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 2210 0, 1)) 2211 printf("swap pctrie zone exhausted, " 2212 "increase kern.maxswzone\n"); 2213 vm_pageout_oom(VM_OOM_SWAPZ); 2214 pause("swzonxp", 10); 2215 } else 2216 uma_zwait(swpctrie_zone); 2217 VM_OBJECT_WLOCK(object); 2218 sb1 = swblk_iter_reinit(blks, object, pindex); 2219 if (sb1 != NULL) { 2220 uma_zfree(swblk_zone, sb); 2221 sb = sb1; 2222 goto allocated; 2223 } 2224 } 2225 } 2226 allocated: 2227 MPASS(sb->p == rounddown(pindex, SWAP_META_PAGES)); 2228 2229 modpi = pindex % SWAP_META_PAGES; 2230 /* Return prior contents of metadata. */ 2231 prev_swapblk = sb->d[modpi]; 2232 if (!nowait_noreplace || prev_swapblk == SWAPBLK_NONE) { 2233 /* Enter block into metadata. */ 2234 sb->d[modpi] = swapblk; 2235 2236 /* 2237 * Free the swblk if we end up with the empty page run. 2238 */ 2239 if (swapblk == SWAPBLK_NONE && 2240 swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 2241 swblk_iter_remove(blks); 2242 uma_zfree(swblk_zone, sb); 2243 } 2244 } 2245 return (prev_swapblk); 2246 } 2247 2248 /* 2249 * SWP_PAGER_META_TRANSFER() - transfer a range of blocks in the srcobject's 2250 * swap metadata into dstobject. 2251 * 2252 * Blocks in src that correspond to holes in dst are transferred. Blocks 2253 * in src that correspond to blocks in dst are freed. 2254 */ 2255 static void 2256 swp_pager_meta_transfer(vm_object_t srcobject, vm_object_t dstobject, 2257 vm_pindex_t pindex, vm_pindex_t count) 2258 { 2259 struct pctrie_iter dstblks, srcblks; 2260 struct page_range range; 2261 struct swblk *sb; 2262 daddr_t blk, d[SWAP_META_PAGES]; 2263 vm_pindex_t last; 2264 int d_mask, i, limit, start; 2265 _Static_assert(8 * sizeof(d_mask) >= SWAP_META_PAGES, 2266 "d_mask not big enough"); 2267 2268 VM_OBJECT_ASSERT_WLOCKED(srcobject); 2269 VM_OBJECT_ASSERT_WLOCKED(dstobject); 2270 2271 if (count == 0 || swblk_is_empty(srcobject)) 2272 return; 2273 2274 swp_pager_init_freerange(&range); 2275 d_mask = 0; 2276 last = pindex + count; 2277 swblk_iter_init_only(&dstblks, dstobject); 2278 for (sb = swblk_iter_limit_init(&srcblks, srcobject, pindex, last), 2279 start = swblk_start(sb, pindex); 2280 sb != NULL; sb = swblk_iter_next(&srcblks), start = 0) { 2281 limit = MIN(last - srcblks.index, SWAP_META_PAGES); 2282 for (i = start; i < limit; i++) { 2283 if (sb->d[i] == SWAPBLK_NONE) 2284 continue; 2285 blk = swp_pager_meta_build(&dstblks, dstobject, 2286 srcblks.index + i - pindex, sb->d[i], true); 2287 if (blk == sb->d[i]) { 2288 /* 2289 * Failed memory allocation stopped transfer; 2290 * save this block for transfer with lock 2291 * released. 2292 */ 2293 d[i] = blk; 2294 d_mask |= 1 << i; 2295 } else if (blk != SWAPBLK_NONE) { 2296 /* Dst has a block at pindex, so free block. */ 2297 swp_pager_update_freerange(&range, sb->d[i]); 2298 } 2299 sb->d[i] = SWAPBLK_NONE; 2300 } 2301 if (swp_pager_swblk_empty(sb, 0, start) && 2302 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2303 swblk_iter_remove(&srcblks); 2304 uma_zfree(swblk_zone, sb); 2305 } 2306 if (d_mask != 0) { 2307 /* Finish block transfer, with the lock released. */ 2308 VM_OBJECT_WUNLOCK(srcobject); 2309 do { 2310 i = ffs(d_mask) - 1; 2311 swp_pager_meta_build(&dstblks, dstobject, 2312 srcblks.index + i - pindex, d[i], false); 2313 d_mask &= ~(1 << i); 2314 } while (d_mask != 0); 2315 VM_OBJECT_WLOCK(srcobject); 2316 2317 /* 2318 * While the lock was not held, the iterator path could 2319 * have become stale, so discard it. 2320 */ 2321 pctrie_iter_reset(&srcblks); 2322 } 2323 } 2324 swp_pager_freeswapspace(&range); 2325 } 2326 2327 /* 2328 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2329 * 2330 * Return freed swap blocks to the swap bitmap, and free emptied swblk 2331 * metadata. With 'freed' set, provide a count of freed blocks that were 2332 * not associated with valid resident pages. 2333 */ 2334 static void 2335 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count, 2336 vm_size_t *freed) 2337 { 2338 struct pctrie_iter blks, pages; 2339 struct page_range range; 2340 struct swblk *sb; 2341 vm_page_t m; 2342 vm_pindex_t last; 2343 vm_size_t fc; 2344 int i, limit, start; 2345 2346 VM_OBJECT_ASSERT_WLOCKED(object); 2347 2348 fc = 0; 2349 if (count == 0 || swblk_is_empty(object)) 2350 goto out; 2351 2352 swp_pager_init_freerange(&range); 2353 vm_page_iter_init(&pages, object); 2354 last = pindex + count; 2355 for (sb = swblk_iter_limit_init(&blks, object, pindex, last), 2356 start = swblk_start(sb, pindex); 2357 sb != NULL; sb = swblk_iter_next(&blks), start = 0) { 2358 limit = MIN(last - blks.index, SWAP_META_PAGES); 2359 for (i = start; i < limit; i++) { 2360 if (sb->d[i] == SWAPBLK_NONE) 2361 continue; 2362 swp_pager_update_freerange(&range, sb->d[i]); 2363 if (freed != NULL) { 2364 m = vm_page_iter_lookup(&pages, blks.index + i); 2365 if (m == NULL || vm_page_none_valid(m)) 2366 fc++; 2367 } 2368 sb->d[i] = SWAPBLK_NONE; 2369 } 2370 if (swp_pager_swblk_empty(sb, 0, start) && 2371 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2372 swblk_iter_remove(&blks); 2373 uma_zfree(swblk_zone, sb); 2374 } 2375 } 2376 swp_pager_freeswapspace(&range); 2377 out: 2378 if (freed != NULL) 2379 *freed = fc; 2380 } 2381 2382 static void 2383 swp_pager_meta_free_block(struct swblk *sb, void *rangev) 2384 { 2385 struct page_range *range = rangev; 2386 2387 for (int i = 0; i < SWAP_META_PAGES; i++) { 2388 if (sb->d[i] != SWAPBLK_NONE) 2389 swp_pager_update_freerange(range, sb->d[i]); 2390 } 2391 uma_zfree(swblk_zone, sb); 2392 } 2393 2394 /* 2395 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2396 * 2397 * This routine locates and destroys all swap metadata associated with 2398 * an object. 2399 */ 2400 static void 2401 swp_pager_meta_free_all(vm_object_t object) 2402 { 2403 struct page_range range; 2404 2405 VM_OBJECT_ASSERT_WLOCKED(object); 2406 2407 swp_pager_init_freerange(&range); 2408 SWAP_PCTRIE_RECLAIM_CALLBACK(&object->un_pager.swp.swp_blks, 2409 swp_pager_meta_free_block, &range); 2410 swp_pager_freeswapspace(&range); 2411 } 2412 2413 /* 2414 * SWP_PAGER_METACTL() - misc control of swap meta data. 2415 * 2416 * This routine is capable of looking up, or removing swapblk 2417 * assignments in the swap meta data. It returns the swapblk being 2418 * looked-up, popped, or SWAPBLK_NONE if the block was invalid. 2419 * 2420 * When acting on a busy resident page and paging is in progress, we 2421 * have to wait until paging is complete but otherwise can act on the 2422 * busy page. 2423 */ 2424 static daddr_t 2425 swp_pager_meta_lookup(vm_object_t object, vm_pindex_t pindex) 2426 { 2427 struct swblk *sb; 2428 2429 VM_OBJECT_ASSERT_LOCKED(object); 2430 2431 /* 2432 * The meta data only exists if the object is OBJT_SWAP 2433 * and even then might not be allocated yet. 2434 */ 2435 KASSERT((object->flags & OBJ_SWAP) != 0, 2436 ("Lookup object not swappable")); 2437 2438 sb = swblk_lookup(object, pindex); 2439 if (sb == NULL) 2440 return (SWAPBLK_NONE); 2441 return (sb->d[pindex % SWAP_META_PAGES]); 2442 } 2443 2444 /* 2445 * Returns the least page index which is greater than or equal to the parameter 2446 * pindex and for which there is a swap block allocated. Returns OBJ_MAX_SIZE 2447 * if are no allocated swap blocks for the object after the requested pindex. 2448 */ 2449 static vm_pindex_t 2450 swap_pager_iter_find_least(struct pctrie_iter *blks, vm_pindex_t pindex) 2451 { 2452 struct swblk *sb; 2453 int i; 2454 2455 if ((sb = swblk_iter_lookup_ge(blks, pindex)) == NULL) 2456 return (OBJ_MAX_SIZE); 2457 if (blks->index < pindex) { 2458 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2459 if (sb->d[i] != SWAPBLK_NONE) 2460 return (blks->index + i); 2461 } 2462 if ((sb = swblk_iter_next(blks)) == NULL) 2463 return (OBJ_MAX_SIZE); 2464 } 2465 for (i = 0; i < SWAP_META_PAGES; i++) { 2466 if (sb->d[i] != SWAPBLK_NONE) 2467 return (blks->index + i); 2468 } 2469 2470 /* 2471 * We get here if a swblk is present in the trie but it 2472 * doesn't map any blocks. 2473 */ 2474 MPASS(0); 2475 return (OBJ_MAX_SIZE); 2476 } 2477 2478 /* 2479 * Returns the least page index which is greater than or equal to the parameter 2480 * pindex and for which there is a swap block allocated. Returns OBJ_MAX_SIZE 2481 * if are no allocated swap blocks for the object after the requested pindex. 2482 */ 2483 vm_pindex_t 2484 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2485 { 2486 struct pctrie_iter blks; 2487 2488 swblk_iter_init_only(&blks, object); 2489 return (swap_pager_iter_find_least(&blks, pindex)); 2490 } 2491 2492 /* 2493 * Is every page in the backing object or swap shadowed in the parent, and 2494 * unbusy and valid in swap? 2495 */ 2496 bool 2497 swap_pager_scan_all_shadowed(vm_object_t object) 2498 { 2499 struct pctrie_iter backing_blks, backing_pages, pages; 2500 vm_object_t backing_object; 2501 vm_page_t p, pp; 2502 vm_pindex_t backing_offset_index, new_pindex, pi, pi_ubound, ps, pv; 2503 2504 VM_OBJECT_ASSERT_WLOCKED(object); 2505 VM_OBJECT_ASSERT_WLOCKED(object->backing_object); 2506 2507 backing_object = object->backing_object; 2508 2509 if ((backing_object->flags & OBJ_ANON) == 0) 2510 return (false); 2511 2512 KASSERT((object->flags & OBJ_ANON) != 0, 2513 ("Shadow object is not anonymous")); 2514 backing_offset_index = OFF_TO_IDX(object->backing_object_offset); 2515 pi_ubound = MIN(backing_object->size, 2516 backing_offset_index + object->size); 2517 vm_page_iter_init(&pages, object); 2518 vm_page_iter_init(&backing_pages, backing_object); 2519 swblk_iter_init_only(&backing_blks, backing_object); 2520 2521 /* 2522 * Only check pages inside the parent object's range and inside the 2523 * parent object's mapping of the backing object. 2524 */ 2525 pv = ps = pi = backing_offset_index - 1; 2526 for (;;) { 2527 if (pi == pv) { 2528 p = vm_page_iter_lookup_ge(&backing_pages, pv + 1); 2529 pv = p != NULL ? p->pindex : backing_object->size; 2530 } 2531 if (pi == ps) 2532 ps = swap_pager_iter_find_least(&backing_blks, ps + 1); 2533 pi = MIN(pv, ps); 2534 if (pi >= pi_ubound) 2535 break; 2536 2537 if (pi == pv) { 2538 /* 2539 * If the backing object page is busy a grandparent or 2540 * older page may still be undergoing CoW. It is not 2541 * safe to collapse the backing object until it is 2542 * quiesced. 2543 */ 2544 if (vm_page_tryxbusy(p) == 0) 2545 return (false); 2546 2547 /* 2548 * We raced with the fault handler that left newly 2549 * allocated invalid page on the object queue and 2550 * retried. 2551 */ 2552 if (!vm_page_all_valid(p)) 2553 break; 2554 2555 /* 2556 * Busy of p disallows fault handler to validate parent 2557 * page (pp, below). 2558 */ 2559 } 2560 2561 /* 2562 * See if the parent has the page or if the parent's object 2563 * pager has the page. If the parent has the page but the page 2564 * is not valid, the parent's object pager must have the page. 2565 * 2566 * If this fails, the parent does not completely shadow the 2567 * object and we might as well give up now. 2568 */ 2569 new_pindex = pi - backing_offset_index; 2570 pp = vm_page_iter_lookup(&pages, new_pindex); 2571 2572 /* 2573 * The valid check here is stable due to object lock being 2574 * required to clear valid and initiate paging. 2575 */ 2576 if ((pp == NULL || vm_page_none_valid(pp)) && 2577 !swap_pager_haspage(object, new_pindex, NULL, NULL)) 2578 break; 2579 if (pi == pv) 2580 vm_page_xunbusy(p); 2581 } 2582 if (pi < pi_ubound) { 2583 if (pi == pv) 2584 vm_page_xunbusy(p); 2585 return (false); 2586 } 2587 return (true); 2588 } 2589 2590 /* 2591 * System call swapon(name) enables swapping on device name, 2592 * which must be in the swdevsw. Return EBUSY 2593 * if already swapping on this device. 2594 */ 2595 #ifndef _SYS_SYSPROTO_H_ 2596 struct swapon_args { 2597 char *name; 2598 }; 2599 #endif 2600 2601 int 2602 sys_swapon(struct thread *td, struct swapon_args *uap) 2603 { 2604 struct vattr attr; 2605 struct vnode *vp; 2606 struct nameidata nd; 2607 int error; 2608 2609 error = priv_check(td, PRIV_SWAPON); 2610 if (error) 2611 return (error); 2612 2613 sx_xlock(&swdev_syscall_lock); 2614 2615 /* 2616 * Swap metadata may not fit in the KVM if we have physical 2617 * memory of >1GB. 2618 */ 2619 if (swblk_zone == NULL) { 2620 error = ENOMEM; 2621 goto done; 2622 } 2623 2624 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | LOCKLEAF | AUDITVNODE1, 2625 UIO_USERSPACE, uap->name); 2626 error = namei(&nd); 2627 if (error) 2628 goto done; 2629 2630 NDFREE_PNBUF(&nd); 2631 vp = nd.ni_vp; 2632 2633 if (vn_isdisk_error(vp, &error)) { 2634 error = swapongeom(vp); 2635 } else if (vp->v_type == VREG && 2636 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2637 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2638 /* 2639 * Allow direct swapping to NFS regular files in the same 2640 * way that nfs_mountroot() sets up diskless swapping. 2641 */ 2642 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2643 } 2644 2645 if (error != 0) 2646 vput(vp); 2647 else 2648 VOP_UNLOCK(vp); 2649 done: 2650 sx_xunlock(&swdev_syscall_lock); 2651 return (error); 2652 } 2653 2654 /* 2655 * Check that the total amount of swap currently configured does not 2656 * exceed half the theoretical maximum. If it does, print a warning 2657 * message. 2658 */ 2659 static void 2660 swapon_check_swzone(void) 2661 { 2662 2663 /* recommend using no more than half that amount */ 2664 if (swap_total > swap_maxpages / 2) { 2665 printf("warning: total configured swap (%lu pages) " 2666 "exceeds maximum recommended amount (%lu pages).\n", 2667 swap_total, swap_maxpages / 2); 2668 printf("warning: increase kern.maxswzone " 2669 "or reduce amount of swap.\n"); 2670 } 2671 } 2672 2673 static void 2674 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2675 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2676 { 2677 struct swdevt *sp, *tsp; 2678 daddr_t dvbase; 2679 2680 /* 2681 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2682 * First chop nblks off to page-align it, then convert. 2683 * 2684 * sw->sw_nblks is in page-sized chunks now too. 2685 */ 2686 nblks &= ~(ctodb(1) - 1); 2687 nblks = dbtoc(nblks); 2688 2689 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2690 sp->sw_blist = blist_create(nblks, M_WAITOK); 2691 sp->sw_vp = vp; 2692 sp->sw_id = id; 2693 sp->sw_dev = dev; 2694 sp->sw_nblks = nblks; 2695 sp->sw_used = 0; 2696 sp->sw_strategy = strategy; 2697 sp->sw_close = close; 2698 sp->sw_flags = flags; 2699 2700 /* 2701 * Do not free the first blocks in order to avoid overwriting 2702 * any bsd label at the front of the partition 2703 */ 2704 blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE), 2705 nblks - howmany(BBSIZE, PAGE_SIZE)); 2706 2707 dvbase = 0; 2708 mtx_lock(&sw_dev_mtx); 2709 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2710 if (tsp->sw_end >= dvbase) { 2711 /* 2712 * We put one uncovered page between the devices 2713 * in order to definitively prevent any cross-device 2714 * I/O requests 2715 */ 2716 dvbase = tsp->sw_end + 1; 2717 } 2718 } 2719 sp->sw_first = dvbase; 2720 sp->sw_end = dvbase + nblks; 2721 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2722 nswapdev++; 2723 swap_pager_avail += nblks - howmany(BBSIZE, PAGE_SIZE); 2724 swap_total += nblks; 2725 swapon_check_swzone(); 2726 swp_sizecheck(); 2727 mtx_unlock(&sw_dev_mtx); 2728 EVENTHANDLER_INVOKE(swapon, sp); 2729 } 2730 2731 /* 2732 * SYSCALL: swapoff(devname) 2733 * 2734 * Disable swapping on the given device. 2735 * 2736 * XXX: Badly designed system call: it should use a device index 2737 * rather than filename as specification. We keep sw_vp around 2738 * only to make this work. 2739 */ 2740 static int 2741 kern_swapoff(struct thread *td, const char *name, enum uio_seg name_seg, 2742 u_int flags) 2743 { 2744 struct vnode *vp; 2745 struct nameidata nd; 2746 struct swdevt *sp; 2747 int error; 2748 2749 error = priv_check(td, PRIV_SWAPOFF); 2750 if (error != 0) 2751 return (error); 2752 if ((flags & ~(SWAPOFF_FORCE)) != 0) 2753 return (EINVAL); 2754 2755 sx_xlock(&swdev_syscall_lock); 2756 2757 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, name_seg, name); 2758 error = namei(&nd); 2759 if (error) 2760 goto done; 2761 NDFREE_PNBUF(&nd); 2762 vp = nd.ni_vp; 2763 2764 mtx_lock(&sw_dev_mtx); 2765 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2766 if (sp->sw_vp == vp) 2767 break; 2768 } 2769 mtx_unlock(&sw_dev_mtx); 2770 if (sp == NULL) { 2771 error = EINVAL; 2772 goto done; 2773 } 2774 error = swapoff_one(sp, td->td_ucred, flags); 2775 done: 2776 sx_xunlock(&swdev_syscall_lock); 2777 return (error); 2778 } 2779 2780 2781 #ifdef COMPAT_FREEBSD13 2782 int 2783 freebsd13_swapoff(struct thread *td, struct freebsd13_swapoff_args *uap) 2784 { 2785 return (kern_swapoff(td, uap->name, UIO_USERSPACE, 0)); 2786 } 2787 #endif 2788 2789 int 2790 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2791 { 2792 return (kern_swapoff(td, uap->name, UIO_USERSPACE, uap->flags)); 2793 } 2794 2795 static int 2796 swapoff_one(struct swdevt *sp, struct ucred *cred, u_int flags) 2797 { 2798 u_long nblks; 2799 #ifdef MAC 2800 int error; 2801 #endif 2802 2803 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2804 #ifdef MAC 2805 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2806 error = mac_system_check_swapoff(cred, sp->sw_vp); 2807 (void) VOP_UNLOCK(sp->sw_vp); 2808 if (error != 0) 2809 return (error); 2810 #endif 2811 nblks = sp->sw_nblks; 2812 2813 /* 2814 * We can turn off this swap device safely only if the 2815 * available virtual memory in the system will fit the amount 2816 * of data we will have to page back in, plus an epsilon so 2817 * the system doesn't become critically low on swap space. 2818 * The vm_free_count() part does not account e.g. for clean 2819 * pages that can be immediately reclaimed without paging, so 2820 * this is a very rough estimation. 2821 * 2822 * On the other hand, not turning swap off on swapoff_all() 2823 * means that we can lose swap data when filesystems go away, 2824 * which is arguably worse. 2825 */ 2826 if ((flags & SWAPOFF_FORCE) == 0 && 2827 vm_free_count() + swap_pager_avail < nblks + nswap_lowat) 2828 return (ENOMEM); 2829 2830 /* 2831 * Prevent further allocations on this device. 2832 */ 2833 mtx_lock(&sw_dev_mtx); 2834 sp->sw_flags |= SW_CLOSING; 2835 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2836 swap_total -= nblks; 2837 mtx_unlock(&sw_dev_mtx); 2838 2839 /* 2840 * Page in the contents of the device and close it. 2841 */ 2842 swap_pager_swapoff(sp); 2843 2844 sp->sw_close(curthread, sp); 2845 mtx_lock(&sw_dev_mtx); 2846 sp->sw_id = NULL; 2847 TAILQ_REMOVE(&swtailq, sp, sw_list); 2848 nswapdev--; 2849 if (nswapdev == 0) { 2850 swap_pager_full = 2; 2851 swap_pager_almost_full = 1; 2852 } 2853 if (swdevhd == sp) 2854 swdevhd = NULL; 2855 mtx_unlock(&sw_dev_mtx); 2856 blist_destroy(sp->sw_blist); 2857 free(sp, M_VMPGDATA); 2858 return (0); 2859 } 2860 2861 void 2862 swapoff_all(void) 2863 { 2864 struct swdevt *sp, *spt; 2865 const char *devname; 2866 int error; 2867 2868 sx_xlock(&swdev_syscall_lock); 2869 2870 mtx_lock(&sw_dev_mtx); 2871 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2872 mtx_unlock(&sw_dev_mtx); 2873 if (vn_isdisk(sp->sw_vp)) 2874 devname = devtoname(sp->sw_vp->v_rdev); 2875 else 2876 devname = "[file]"; 2877 error = swapoff_one(sp, thread0.td_ucred, SWAPOFF_FORCE); 2878 if (error != 0) { 2879 printf("Cannot remove swap device %s (error=%d), " 2880 "skipping.\n", devname, error); 2881 } else if (bootverbose) { 2882 printf("Swap device %s removed.\n", devname); 2883 } 2884 mtx_lock(&sw_dev_mtx); 2885 } 2886 mtx_unlock(&sw_dev_mtx); 2887 2888 sx_xunlock(&swdev_syscall_lock); 2889 } 2890 2891 void 2892 swap_pager_status(int *total, int *used) 2893 { 2894 2895 *total = swap_total; 2896 *used = swap_total - swap_pager_avail - 2897 nswapdev * howmany(BBSIZE, PAGE_SIZE); 2898 } 2899 2900 int 2901 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2902 { 2903 struct swdevt *sp; 2904 const char *tmp_devname; 2905 int error, n; 2906 2907 n = 0; 2908 error = ENOENT; 2909 mtx_lock(&sw_dev_mtx); 2910 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2911 if (n != name) { 2912 n++; 2913 continue; 2914 } 2915 xs->xsw_version = XSWDEV_VERSION; 2916 xs->xsw_dev = sp->sw_dev; 2917 xs->xsw_flags = sp->sw_flags; 2918 xs->xsw_nblks = sp->sw_nblks; 2919 xs->xsw_used = sp->sw_used; 2920 if (devname != NULL) { 2921 if (vn_isdisk(sp->sw_vp)) 2922 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2923 else 2924 tmp_devname = "[file]"; 2925 strncpy(devname, tmp_devname, len); 2926 } 2927 error = 0; 2928 break; 2929 } 2930 mtx_unlock(&sw_dev_mtx); 2931 return (error); 2932 } 2933 2934 #if defined(COMPAT_FREEBSD11) 2935 #define XSWDEV_VERSION_11 1 2936 struct xswdev11 { 2937 u_int xsw_version; 2938 uint32_t xsw_dev; 2939 int xsw_flags; 2940 int xsw_nblks; 2941 int xsw_used; 2942 }; 2943 #endif 2944 2945 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2946 struct xswdev32 { 2947 u_int xsw_version; 2948 u_int xsw_dev1, xsw_dev2; 2949 int xsw_flags; 2950 int xsw_nblks; 2951 int xsw_used; 2952 }; 2953 #endif 2954 2955 static int 2956 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2957 { 2958 struct xswdev xs; 2959 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2960 struct xswdev32 xs32; 2961 #endif 2962 #if defined(COMPAT_FREEBSD11) 2963 struct xswdev11 xs11; 2964 #endif 2965 int error; 2966 2967 if (arg2 != 1) /* name length */ 2968 return (EINVAL); 2969 2970 memset(&xs, 0, sizeof(xs)); 2971 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2972 if (error != 0) 2973 return (error); 2974 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2975 if (req->oldlen == sizeof(xs32)) { 2976 memset(&xs32, 0, sizeof(xs32)); 2977 xs32.xsw_version = XSWDEV_VERSION; 2978 xs32.xsw_dev1 = xs.xsw_dev; 2979 xs32.xsw_dev2 = xs.xsw_dev >> 32; 2980 xs32.xsw_flags = xs.xsw_flags; 2981 xs32.xsw_nblks = xs.xsw_nblks; 2982 xs32.xsw_used = xs.xsw_used; 2983 error = SYSCTL_OUT(req, &xs32, sizeof(xs32)); 2984 return (error); 2985 } 2986 #endif 2987 #if defined(COMPAT_FREEBSD11) 2988 if (req->oldlen == sizeof(xs11)) { 2989 memset(&xs11, 0, sizeof(xs11)); 2990 xs11.xsw_version = XSWDEV_VERSION_11; 2991 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2992 xs11.xsw_flags = xs.xsw_flags; 2993 xs11.xsw_nblks = xs.xsw_nblks; 2994 xs11.xsw_used = xs.xsw_used; 2995 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2996 return (error); 2997 } 2998 #endif 2999 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 3000 return (error); 3001 } 3002 3003 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 3004 "Number of swap devices"); 3005 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 3006 sysctl_vm_swap_info, 3007 "Swap statistics by device"); 3008 3009 /* 3010 * Count the approximate swap usage in pages for a vmspace. The 3011 * shadowed or not yet copied on write swap blocks are not accounted. 3012 * The map must be locked. 3013 */ 3014 long 3015 vmspace_swap_count(struct vmspace *vmspace) 3016 { 3017 struct pctrie_iter blks; 3018 vm_map_t map; 3019 vm_map_entry_t cur; 3020 vm_object_t object; 3021 struct swblk *sb; 3022 vm_pindex_t e, pi; 3023 long count; 3024 int i, limit, start; 3025 3026 map = &vmspace->vm_map; 3027 count = 0; 3028 3029 VM_MAP_ENTRY_FOREACH(cur, map) { 3030 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 3031 continue; 3032 object = cur->object.vm_object; 3033 if (object == NULL || (object->flags & OBJ_SWAP) == 0) 3034 continue; 3035 VM_OBJECT_RLOCK(object); 3036 if ((object->flags & OBJ_SWAP) == 0) 3037 goto unlock; 3038 pi = OFF_TO_IDX(cur->offset); 3039 e = pi + OFF_TO_IDX(cur->end - cur->start); 3040 for (sb = swblk_iter_limit_init(&blks, object, pi, e), 3041 start = swblk_start(sb, pi); 3042 sb != NULL; sb = swblk_iter_next(&blks), start = 0) { 3043 limit = MIN(e - blks.index, SWAP_META_PAGES); 3044 for (i = start; i < limit; i++) { 3045 if (sb->d[i] != SWAPBLK_NONE) 3046 count++; 3047 } 3048 } 3049 unlock: 3050 VM_OBJECT_RUNLOCK(object); 3051 } 3052 return (count); 3053 } 3054 3055 /* 3056 * GEOM backend 3057 * 3058 * Swapping onto disk devices. 3059 * 3060 */ 3061 3062 static g_orphan_t swapgeom_orphan; 3063 3064 static struct g_class g_swap_class = { 3065 .name = "SWAP", 3066 .version = G_VERSION, 3067 .orphan = swapgeom_orphan, 3068 }; 3069 3070 DECLARE_GEOM_CLASS(g_swap_class, g_class); 3071 3072 static void 3073 swapgeom_close_ev(void *arg, int flags) 3074 { 3075 struct g_consumer *cp; 3076 3077 cp = arg; 3078 g_access(cp, -1, -1, 0); 3079 g_detach(cp); 3080 g_destroy_consumer(cp); 3081 } 3082 3083 /* 3084 * Add a reference to the g_consumer for an inflight transaction. 3085 */ 3086 static void 3087 swapgeom_acquire(struct g_consumer *cp) 3088 { 3089 3090 mtx_assert(&sw_dev_mtx, MA_OWNED); 3091 cp->index++; 3092 } 3093 3094 /* 3095 * Remove a reference from the g_consumer. Post a close event if all 3096 * references go away, since the function might be called from the 3097 * biodone context. 3098 */ 3099 static void 3100 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 3101 { 3102 3103 mtx_assert(&sw_dev_mtx, MA_OWNED); 3104 cp->index--; 3105 if (cp->index == 0) { 3106 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 3107 sp->sw_id = NULL; 3108 } 3109 } 3110 3111 static void 3112 swapgeom_done(struct bio *bp2) 3113 { 3114 struct swdevt *sp; 3115 struct buf *bp; 3116 struct g_consumer *cp; 3117 3118 bp = bp2->bio_caller2; 3119 cp = bp2->bio_from; 3120 bp->b_ioflags = bp2->bio_flags; 3121 if (bp2->bio_error) 3122 bp->b_ioflags |= BIO_ERROR; 3123 bp->b_resid = bp->b_bcount - bp2->bio_completed; 3124 bp->b_error = bp2->bio_error; 3125 bp->b_caller1 = NULL; 3126 bufdone(bp); 3127 sp = bp2->bio_caller1; 3128 mtx_lock(&sw_dev_mtx); 3129 swapgeom_release(cp, sp); 3130 mtx_unlock(&sw_dev_mtx); 3131 g_destroy_bio(bp2); 3132 } 3133 3134 static void 3135 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 3136 { 3137 struct bio *bio; 3138 struct g_consumer *cp; 3139 3140 mtx_lock(&sw_dev_mtx); 3141 cp = sp->sw_id; 3142 if (cp == NULL) { 3143 mtx_unlock(&sw_dev_mtx); 3144 bp->b_error = ENXIO; 3145 bp->b_ioflags |= BIO_ERROR; 3146 bufdone(bp); 3147 return; 3148 } 3149 swapgeom_acquire(cp); 3150 mtx_unlock(&sw_dev_mtx); 3151 if (bp->b_iocmd == BIO_WRITE) 3152 bio = g_new_bio(); 3153 else 3154 bio = g_alloc_bio(); 3155 if (bio == NULL) { 3156 mtx_lock(&sw_dev_mtx); 3157 swapgeom_release(cp, sp); 3158 mtx_unlock(&sw_dev_mtx); 3159 bp->b_error = ENOMEM; 3160 bp->b_ioflags |= BIO_ERROR; 3161 printf("swap_pager: cannot allocate bio\n"); 3162 bufdone(bp); 3163 return; 3164 } 3165 3166 bp->b_caller1 = bio; 3167 bio->bio_caller1 = sp; 3168 bio->bio_caller2 = bp; 3169 bio->bio_cmd = bp->b_iocmd; 3170 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 3171 bio->bio_length = bp->b_bcount; 3172 bio->bio_done = swapgeom_done; 3173 bio->bio_flags |= BIO_SWAP; 3174 if (!buf_mapped(bp)) { 3175 bio->bio_ma = bp->b_pages; 3176 bio->bio_data = unmapped_buf; 3177 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 3178 bio->bio_ma_n = bp->b_npages; 3179 bio->bio_flags |= BIO_UNMAPPED; 3180 } else { 3181 bio->bio_data = bp->b_data; 3182 bio->bio_ma = NULL; 3183 } 3184 g_io_request(bio, cp); 3185 return; 3186 } 3187 3188 static void 3189 swapgeom_orphan(struct g_consumer *cp) 3190 { 3191 struct swdevt *sp; 3192 int destroy; 3193 3194 mtx_lock(&sw_dev_mtx); 3195 TAILQ_FOREACH(sp, &swtailq, sw_list) { 3196 if (sp->sw_id == cp) { 3197 sp->sw_flags |= SW_CLOSING; 3198 break; 3199 } 3200 } 3201 /* 3202 * Drop reference we were created with. Do directly since we're in a 3203 * special context where we don't have to queue the call to 3204 * swapgeom_close_ev(). 3205 */ 3206 cp->index--; 3207 destroy = ((sp != NULL) && (cp->index == 0)); 3208 if (destroy) 3209 sp->sw_id = NULL; 3210 mtx_unlock(&sw_dev_mtx); 3211 if (destroy) 3212 swapgeom_close_ev(cp, 0); 3213 } 3214 3215 static void 3216 swapgeom_close(struct thread *td, struct swdevt *sw) 3217 { 3218 struct g_consumer *cp; 3219 3220 mtx_lock(&sw_dev_mtx); 3221 cp = sw->sw_id; 3222 sw->sw_id = NULL; 3223 mtx_unlock(&sw_dev_mtx); 3224 3225 /* 3226 * swapgeom_close() may be called from the biodone context, 3227 * where we cannot perform topology changes. Delegate the 3228 * work to the events thread. 3229 */ 3230 if (cp != NULL) 3231 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 3232 } 3233 3234 static int 3235 swapongeom_locked(struct cdev *dev, struct vnode *vp) 3236 { 3237 struct g_provider *pp; 3238 struct g_consumer *cp; 3239 static struct g_geom *gp; 3240 struct swdevt *sp; 3241 u_long nblks; 3242 int error; 3243 3244 pp = g_dev_getprovider(dev); 3245 if (pp == NULL) 3246 return (ENODEV); 3247 mtx_lock(&sw_dev_mtx); 3248 TAILQ_FOREACH(sp, &swtailq, sw_list) { 3249 cp = sp->sw_id; 3250 if (cp != NULL && cp->provider == pp) { 3251 mtx_unlock(&sw_dev_mtx); 3252 return (EBUSY); 3253 } 3254 } 3255 mtx_unlock(&sw_dev_mtx); 3256 if (gp == NULL) 3257 gp = g_new_geomf(&g_swap_class, "swap"); 3258 cp = g_new_consumer(gp); 3259 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 3260 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 3261 g_attach(cp, pp); 3262 /* 3263 * XXX: Every time you think you can improve the margin for 3264 * footshooting, somebody depends on the ability to do so: 3265 * savecore(8) wants to write to our swapdev so we cannot 3266 * set an exclusive count :-( 3267 */ 3268 error = g_access(cp, 1, 1, 0); 3269 if (error != 0) { 3270 g_detach(cp); 3271 g_destroy_consumer(cp); 3272 return (error); 3273 } 3274 nblks = pp->mediasize / DEV_BSIZE; 3275 swaponsomething(vp, cp, nblks, swapgeom_strategy, 3276 swapgeom_close, dev2udev(dev), 3277 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 3278 return (0); 3279 } 3280 3281 static int 3282 swapongeom(struct vnode *vp) 3283 { 3284 int error; 3285 3286 ASSERT_VOP_ELOCKED(vp, "swapongeom"); 3287 if (vp->v_type != VCHR || VN_IS_DOOMED(vp)) { 3288 error = ENOENT; 3289 } else { 3290 g_topology_lock(); 3291 error = swapongeom_locked(vp->v_rdev, vp); 3292 g_topology_unlock(); 3293 } 3294 return (error); 3295 } 3296 3297 /* 3298 * VNODE backend 3299 * 3300 * This is used mainly for network filesystem (read: probably only tested 3301 * with NFS) swapfiles. 3302 * 3303 */ 3304 3305 static void 3306 swapdev_strategy(struct buf *bp, struct swdevt *sp) 3307 { 3308 struct vnode *vp2; 3309 3310 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 3311 3312 vp2 = sp->sw_id; 3313 vhold(vp2); 3314 if (bp->b_iocmd == BIO_WRITE) { 3315 vn_lock(vp2, LK_EXCLUSIVE | LK_RETRY); 3316 if (bp->b_bufobj) 3317 bufobj_wdrop(bp->b_bufobj); 3318 bufobj_wref(&vp2->v_bufobj); 3319 } else { 3320 vn_lock(vp2, LK_SHARED | LK_RETRY); 3321 } 3322 if (bp->b_bufobj != &vp2->v_bufobj) 3323 bp->b_bufobj = &vp2->v_bufobj; 3324 bp->b_vp = vp2; 3325 bp->b_iooffset = dbtob(bp->b_blkno); 3326 bstrategy(bp); 3327 VOP_UNLOCK(vp2); 3328 } 3329 3330 static void 3331 swapdev_close(struct thread *td, struct swdevt *sp) 3332 { 3333 struct vnode *vp; 3334 3335 vp = sp->sw_vp; 3336 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 3337 VOP_CLOSE(vp, FREAD | FWRITE, td->td_ucred, td); 3338 vput(vp); 3339 } 3340 3341 static int 3342 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 3343 { 3344 struct swdevt *sp; 3345 int error; 3346 3347 ASSERT_VOP_ELOCKED(vp, "swaponvp"); 3348 if (nblks == 0) 3349 return (ENXIO); 3350 mtx_lock(&sw_dev_mtx); 3351 TAILQ_FOREACH(sp, &swtailq, sw_list) { 3352 if (sp->sw_id == vp) { 3353 mtx_unlock(&sw_dev_mtx); 3354 return (EBUSY); 3355 } 3356 } 3357 mtx_unlock(&sw_dev_mtx); 3358 3359 #ifdef MAC 3360 error = mac_system_check_swapon(td->td_ucred, vp); 3361 if (error == 0) 3362 #endif 3363 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 3364 if (error != 0) 3365 return (error); 3366 3367 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 3368 NODEV, 0); 3369 return (0); 3370 } 3371 3372 static int 3373 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 3374 { 3375 int error, new, n; 3376 3377 new = nsw_wcount_async_max; 3378 error = sysctl_handle_int(oidp, &new, 0, req); 3379 if (error != 0 || req->newptr == NULL) 3380 return (error); 3381 3382 if (new > nswbuf / 2 || new < 1) 3383 return (EINVAL); 3384 3385 mtx_lock(&swbuf_mtx); 3386 while (nsw_wcount_async_max != new) { 3387 /* 3388 * Adjust difference. If the current async count is too low, 3389 * we will need to sqeeze our update slowly in. Sleep with a 3390 * higher priority than getpbuf() to finish faster. 3391 */ 3392 n = new - nsw_wcount_async_max; 3393 if (nsw_wcount_async + n >= 0) { 3394 nsw_wcount_async += n; 3395 nsw_wcount_async_max += n; 3396 wakeup(&nsw_wcount_async); 3397 } else { 3398 nsw_wcount_async_max -= nsw_wcount_async; 3399 nsw_wcount_async = 0; 3400 msleep(&nsw_wcount_async, &swbuf_mtx, PSWP, 3401 "swpsysctl", 0); 3402 } 3403 } 3404 mtx_unlock(&swbuf_mtx); 3405 3406 return (0); 3407 } 3408 3409 static void 3410 swap_pager_update_writecount(vm_object_t object, vm_offset_t start, 3411 vm_offset_t end) 3412 { 3413 3414 VM_OBJECT_WLOCK(object); 3415 KASSERT((object->flags & OBJ_ANON) == 0, 3416 ("Splittable object with writecount")); 3417 object->un_pager.swp.writemappings += (vm_ooffset_t)end - start; 3418 VM_OBJECT_WUNLOCK(object); 3419 } 3420 3421 static void 3422 swap_pager_release_writecount(vm_object_t object, vm_offset_t start, 3423 vm_offset_t end) 3424 { 3425 3426 VM_OBJECT_WLOCK(object); 3427 KASSERT((object->flags & OBJ_ANON) == 0, 3428 ("Splittable object with writecount")); 3429 KASSERT(object->un_pager.swp.writemappings >= (vm_ooffset_t)end - start, 3430 ("swap obj %p writecount %jx dec %jx", object, 3431 (uintmax_t)object->un_pager.swp.writemappings, 3432 (uintmax_t)((vm_ooffset_t)end - start))); 3433 object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start; 3434 VM_OBJECT_WUNLOCK(object); 3435 } 3436