1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (c) 1998 Matthew Dillon, 5 * Copyright (c) 1994 John S. Dyson 6 * Copyright (c) 1990 University of Utah. 7 * Copyright (c) 1982, 1986, 1989, 1993 8 * The Regents of the University of California. All rights reserved. 9 * 10 * This code is derived from software contributed to Berkeley by 11 * the Systems Programming Group of the University of Utah Computer 12 * Science Department. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. All advertising materials mentioning features or use of this software 23 * must display the following acknowledgement: 24 * This product includes software developed by the University of 25 * California, Berkeley and its contributors. 26 * 4. Neither the name of the University nor the names of its contributors 27 * may be used to endorse or promote products derived from this software 28 * without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 40 * SUCH DAMAGE. 41 * 42 * New Swap System 43 * Matthew Dillon 44 * 45 * Radix Bitmap 'blists'. 46 * 47 * - The new swapper uses the new radix bitmap code. This should scale 48 * to arbitrarily small or arbitrarily large swap spaces and an almost 49 * arbitrary degree of fragmentation. 50 * 51 * Features: 52 * 53 * - on the fly reallocation of swap during putpages. The new system 54 * does not try to keep previously allocated swap blocks for dirty 55 * pages. 56 * 57 * - on the fly deallocation of swap 58 * 59 * - No more garbage collection required. Unnecessarily allocated swap 60 * blocks only exist for dirty vm_page_t's now and these are already 61 * cycled (in a high-load system) by the pager. We also do on-the-fly 62 * removal of invalidated swap blocks when a page is destroyed 63 * or renamed. 64 * 65 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$ 66 * 67 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94 68 * @(#)vm_swap.c 8.5 (Berkeley) 2/17/94 69 */ 70 71 #include <sys/cdefs.h> 72 __FBSDID("$FreeBSD$"); 73 74 #include "opt_vm.h" 75 76 #include <sys/param.h> 77 #include <sys/bio.h> 78 #include <sys/blist.h> 79 #include <sys/buf.h> 80 #include <sys/conf.h> 81 #include <sys/disk.h> 82 #include <sys/disklabel.h> 83 #include <sys/eventhandler.h> 84 #include <sys/fcntl.h> 85 #include <sys/lock.h> 86 #include <sys/kernel.h> 87 #include <sys/mount.h> 88 #include <sys/namei.h> 89 #include <sys/malloc.h> 90 #include <sys/pctrie.h> 91 #include <sys/priv.h> 92 #include <sys/proc.h> 93 #include <sys/racct.h> 94 #include <sys/resource.h> 95 #include <sys/resourcevar.h> 96 #include <sys/rwlock.h> 97 #include <sys/sbuf.h> 98 #include <sys/sysctl.h> 99 #include <sys/sysproto.h> 100 #include <sys/systm.h> 101 #include <sys/sx.h> 102 #include <sys/vmmeter.h> 103 #include <sys/vnode.h> 104 105 #include <security/mac/mac_framework.h> 106 107 #include <vm/vm.h> 108 #include <vm/pmap.h> 109 #include <vm/vm_map.h> 110 #include <vm/vm_kern.h> 111 #include <vm/vm_object.h> 112 #include <vm/vm_page.h> 113 #include <vm/vm_pager.h> 114 #include <vm/vm_pageout.h> 115 #include <vm/vm_param.h> 116 #include <vm/swap_pager.h> 117 #include <vm/vm_extern.h> 118 #include <vm/uma.h> 119 120 #include <geom/geom.h> 121 122 /* 123 * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64. 124 * The 64-page limit is due to the radix code (kern/subr_blist.c). 125 */ 126 #ifndef MAX_PAGEOUT_CLUSTER 127 #define MAX_PAGEOUT_CLUSTER 32 128 #endif 129 130 #if !defined(SWB_NPAGES) 131 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER 132 #endif 133 134 #define SWAP_META_PAGES PCTRIE_COUNT 135 136 /* 137 * A swblk structure maps each page index within a 138 * SWAP_META_PAGES-aligned and sized range to the address of an 139 * on-disk swap block (or SWAPBLK_NONE). The collection of these 140 * mappings for an entire vm object is implemented as a pc-trie. 141 */ 142 struct swblk { 143 vm_pindex_t p; 144 daddr_t d[SWAP_META_PAGES]; 145 }; 146 147 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); 148 static struct mtx sw_dev_mtx; 149 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 150 static struct swdevt *swdevhd; /* Allocate from here next */ 151 static int nswapdev; /* Number of swap devices */ 152 int swap_pager_avail; 153 static struct sx swdev_syscall_lock; /* serialize swap(on|off) */ 154 155 static u_long swap_reserved; 156 static u_long swap_total; 157 static int sysctl_page_shift(SYSCTL_HANDLER_ARGS); 158 SYSCTL_PROC(_vm, OID_AUTO, swap_reserved, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 159 &swap_reserved, 0, sysctl_page_shift, "A", 160 "Amount of swap storage needed to back all allocated anonymous memory."); 161 SYSCTL_PROC(_vm, OID_AUTO, swap_total, CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, 162 &swap_total, 0, sysctl_page_shift, "A", 163 "Total amount of available swap storage."); 164 165 static int overcommit = 0; 166 SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &overcommit, 0, 167 "Configure virtual memory overcommit behavior. See tuning(7) " 168 "for details."); 169 static unsigned long swzone; 170 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 171 "Actual size of swap metadata zone"); 172 static unsigned long swap_maxpages; 173 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, 174 "Maximum amount of swap supported"); 175 176 /* bits from overcommit */ 177 #define SWAP_RESERVE_FORCE_ON (1 << 0) 178 #define SWAP_RESERVE_RLIMIT_ON (1 << 1) 179 #define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2) 180 181 static int 182 sysctl_page_shift(SYSCTL_HANDLER_ARGS) 183 { 184 uint64_t newval; 185 u_long value = *(u_long *)arg1; 186 187 newval = ((uint64_t)value) << PAGE_SHIFT; 188 return (sysctl_handle_64(oidp, &newval, 0, req)); 189 } 190 191 int 192 swap_reserve(vm_ooffset_t incr) 193 { 194 195 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 196 } 197 198 int 199 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 200 { 201 u_long r, s, prev, pincr; 202 int res, error; 203 static int curfail; 204 static struct timeval lastfail; 205 struct uidinfo *uip; 206 207 uip = cred->cr_ruidinfo; 208 209 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 210 (uintmax_t)incr)); 211 212 #ifdef RACCT 213 if (racct_enable) { 214 PROC_LOCK(curproc); 215 error = racct_add(curproc, RACCT_SWAP, incr); 216 PROC_UNLOCK(curproc); 217 if (error != 0) 218 return (0); 219 } 220 #endif 221 222 pincr = atop(incr); 223 res = 0; 224 prev = atomic_fetchadd_long(&swap_reserved, pincr); 225 r = prev + pincr; 226 if (overcommit & SWAP_RESERVE_ALLOW_NONWIRED) { 227 s = vm_cnt.v_page_count - vm_cnt.v_free_reserved - 228 vm_wire_count(); 229 } else 230 s = 0; 231 s += swap_total; 232 if ((overcommit & SWAP_RESERVE_FORCE_ON) == 0 || r <= s || 233 (error = priv_check(curthread, PRIV_VM_SWAP_NOQUOTA)) == 0) { 234 res = 1; 235 } else { 236 prev = atomic_fetchadd_long(&swap_reserved, -pincr); 237 if (prev < pincr) 238 panic("swap_reserved < incr on overcommit fail"); 239 } 240 if (res) { 241 prev = atomic_fetchadd_long(&uip->ui_vmsize, pincr); 242 if ((overcommit & SWAP_RESERVE_RLIMIT_ON) != 0 && 243 prev + pincr > lim_cur(curthread, RLIMIT_SWAP) && 244 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT)) { 245 res = 0; 246 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pincr); 247 if (prev < pincr) 248 panic("uip->ui_vmsize < incr on overcommit fail"); 249 } 250 } 251 if (!res && ppsratecheck(&lastfail, &curfail, 1)) { 252 printf("uid %d, pid %d: swap reservation for %jd bytes failed\n", 253 uip->ui_uid, curproc->p_pid, incr); 254 } 255 256 #ifdef RACCT 257 if (racct_enable && !res) { 258 PROC_LOCK(curproc); 259 racct_sub(curproc, RACCT_SWAP, incr); 260 PROC_UNLOCK(curproc); 261 } 262 #endif 263 264 return (res); 265 } 266 267 void 268 swap_reserve_force(vm_ooffset_t incr) 269 { 270 struct uidinfo *uip; 271 u_long pincr; 272 273 KASSERT((incr & PAGE_MASK) == 0, ("%s: incr: %ju & PAGE_MASK", __func__, 274 (uintmax_t)incr)); 275 276 PROC_LOCK(curproc); 277 #ifdef RACCT 278 if (racct_enable) 279 racct_add_force(curproc, RACCT_SWAP, incr); 280 #endif 281 pincr = atop(incr); 282 atomic_add_long(&swap_reserved, pincr); 283 uip = curproc->p_ucred->cr_ruidinfo; 284 atomic_add_long(&uip->ui_vmsize, pincr); 285 PROC_UNLOCK(curproc); 286 } 287 288 void 289 swap_release(vm_ooffset_t decr) 290 { 291 struct ucred *cred; 292 293 PROC_LOCK(curproc); 294 cred = curproc->p_ucred; 295 swap_release_by_cred(decr, cred); 296 PROC_UNLOCK(curproc); 297 } 298 299 void 300 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 301 { 302 u_long prev, pdecr; 303 struct uidinfo *uip; 304 305 uip = cred->cr_ruidinfo; 306 307 KASSERT((decr & PAGE_MASK) == 0, ("%s: decr: %ju & PAGE_MASK", __func__, 308 (uintmax_t)decr)); 309 310 pdecr = atop(decr); 311 prev = atomic_fetchadd_long(&swap_reserved, -pdecr); 312 if (prev < pdecr) 313 panic("swap_reserved < decr"); 314 315 prev = atomic_fetchadd_long(&uip->ui_vmsize, -pdecr); 316 if (prev < pdecr) 317 printf("negative vmsize for uid = %d\n", uip->ui_uid); 318 #ifdef RACCT 319 if (racct_enable) 320 racct_sub_cred(cred, RACCT_SWAP, decr); 321 #endif 322 } 323 324 #define SWM_POP 0x01 /* pop out */ 325 326 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 327 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 328 static struct mtx swbuf_mtx; /* to sync nsw_wcount_async */ 329 static int nsw_wcount_async; /* limit async write buffers */ 330 static int nsw_wcount_async_max;/* assigned maximum */ 331 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 332 333 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 334 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 335 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 336 "Maximum running async swap ops"); 337 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS); 338 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD | 339 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A", 340 "Swap Fragmentation Info"); 341 342 static struct sx sw_alloc_sx; 343 344 /* 345 * "named" and "unnamed" anon region objects. Try to reduce the overhead 346 * of searching a named list by hashing it just a little. 347 */ 348 349 #define NOBJLISTS 8 350 351 #define NOBJLIST(handle) \ 352 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 353 354 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 355 static uma_zone_t swwbuf_zone; 356 static uma_zone_t swrbuf_zone; 357 static uma_zone_t swblk_zone; 358 static uma_zone_t swpctrie_zone; 359 360 /* 361 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 362 * calls hooked from other parts of the VM system and do not appear here. 363 * (see vm/swap_pager.h). 364 */ 365 static vm_object_t 366 swap_pager_alloc(void *handle, vm_ooffset_t size, 367 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 368 static void swap_pager_dealloc(vm_object_t object); 369 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, 370 int *); 371 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, 372 int *, pgo_getpages_iodone_t, void *); 373 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 374 static boolean_t 375 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 376 static void swap_pager_init(void); 377 static void swap_pager_unswapped(vm_page_t); 378 static void swap_pager_swapoff(struct swdevt *sp); 379 static void swap_pager_update_writecount(vm_object_t object, 380 vm_offset_t start, vm_offset_t end); 381 static void swap_pager_release_writecount(vm_object_t object, 382 vm_offset_t start, vm_offset_t end); 383 384 struct pagerops swappagerops = { 385 .pgo_init = swap_pager_init, /* early system initialization of pager */ 386 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 387 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 388 .pgo_getpages = swap_pager_getpages, /* pagein */ 389 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 390 .pgo_putpages = swap_pager_putpages, /* pageout */ 391 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 392 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 393 .pgo_update_writecount = swap_pager_update_writecount, 394 .pgo_release_writecount = swap_pager_release_writecount, 395 }; 396 397 /* 398 * swap_*() routines are externally accessible. swp_*() routines are 399 * internal. 400 */ 401 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 402 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 403 404 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 405 "Maximum size of a swap block in pages"); 406 407 static void swp_sizecheck(void); 408 static void swp_pager_async_iodone(struct buf *bp); 409 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit); 410 static int swapongeom(struct vnode *); 411 static int swaponvp(struct thread *, struct vnode *, u_long); 412 static int swapoff_one(struct swdevt *sp, struct ucred *cred); 413 414 /* 415 * Swap bitmap functions 416 */ 417 static void swp_pager_freeswapspace(daddr_t blk, daddr_t npages); 418 static daddr_t swp_pager_getswapspace(int *npages, int limit); 419 420 /* 421 * Metadata functions 422 */ 423 static daddr_t swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 424 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 425 static void swp_pager_meta_transfer(vm_object_t src, vm_object_t dst, 426 vm_pindex_t pindex, vm_pindex_t count); 427 static void swp_pager_meta_free_all(vm_object_t); 428 static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 429 430 static void 431 swp_pager_init_freerange(daddr_t *start, daddr_t *num) 432 { 433 434 *start = SWAPBLK_NONE; 435 *num = 0; 436 } 437 438 static void 439 swp_pager_update_freerange(daddr_t *start, daddr_t *num, daddr_t addr) 440 { 441 442 if (*start + *num == addr) { 443 (*num)++; 444 } else { 445 swp_pager_freeswapspace(*start, *num); 446 *start = addr; 447 *num = 1; 448 } 449 } 450 451 static void * 452 swblk_trie_alloc(struct pctrie *ptree) 453 { 454 455 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? 456 M_USE_RESERVE : 0))); 457 } 458 459 static void 460 swblk_trie_free(struct pctrie *ptree, void *node) 461 { 462 463 uma_zfree(swpctrie_zone, node); 464 } 465 466 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); 467 468 /* 469 * SWP_SIZECHECK() - update swap_pager_full indication 470 * 471 * update the swap_pager_almost_full indication and warn when we are 472 * about to run out of swap space, using lowat/hiwat hysteresis. 473 * 474 * Clear swap_pager_full ( task killing ) indication when lowat is met. 475 * 476 * No restrictions on call 477 * This routine may not block. 478 */ 479 static void 480 swp_sizecheck(void) 481 { 482 483 if (swap_pager_avail < nswap_lowat) { 484 if (swap_pager_almost_full == 0) { 485 printf("swap_pager: out of swap space\n"); 486 swap_pager_almost_full = 1; 487 } 488 } else { 489 swap_pager_full = 0; 490 if (swap_pager_avail > nswap_hiwat) 491 swap_pager_almost_full = 0; 492 } 493 } 494 495 /* 496 * SWAP_PAGER_INIT() - initialize the swap pager! 497 * 498 * Expected to be started from system init. NOTE: This code is run 499 * before much else so be careful what you depend on. Most of the VM 500 * system has yet to be initialized at this point. 501 */ 502 static void 503 swap_pager_init(void) 504 { 505 /* 506 * Initialize object lists 507 */ 508 int i; 509 510 for (i = 0; i < NOBJLISTS; ++i) 511 TAILQ_INIT(&swap_pager_object_list[i]); 512 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 513 sx_init(&sw_alloc_sx, "swspsx"); 514 sx_init(&swdev_syscall_lock, "swsysc"); 515 } 516 517 /* 518 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 519 * 520 * Expected to be started from pageout process once, prior to entering 521 * its main loop. 522 */ 523 void 524 swap_pager_swap_init(void) 525 { 526 unsigned long n, n2; 527 528 /* 529 * Number of in-transit swap bp operations. Don't 530 * exhaust the pbufs completely. Make sure we 531 * initialize workable values (0 will work for hysteresis 532 * but it isn't very efficient). 533 * 534 * The nsw_cluster_max is constrained by the bp->b_pages[] 535 * array, which has MAXPHYS / PAGE_SIZE entries, and our locally 536 * defined MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 537 * constrained by the swap device interleave stripe size. 538 * 539 * Currently we hardwire nsw_wcount_async to 4. This limit is 540 * designed to prevent other I/O from having high latencies due to 541 * our pageout I/O. The value 4 works well for one or two active swap 542 * devices but is probably a little low if you have more. Even so, 543 * a higher value would probably generate only a limited improvement 544 * with three or four active swap devices since the system does not 545 * typically have to pageout at extreme bandwidths. We will want 546 * at least 2 per swap devices, and 4 is a pretty good value if you 547 * have one NFS swap device due to the command/ack latency over NFS. 548 * So it all works out pretty well. 549 */ 550 nsw_cluster_max = min(MAXPHYS / PAGE_SIZE, MAX_PAGEOUT_CLUSTER); 551 552 nsw_wcount_async = 4; 553 nsw_wcount_async_max = nsw_wcount_async; 554 mtx_init(&swbuf_mtx, "async swbuf mutex", NULL, MTX_DEF); 555 556 swwbuf_zone = pbuf_zsecond_create("swwbuf", nswbuf / 4); 557 swrbuf_zone = pbuf_zsecond_create("swrbuf", nswbuf / 2); 558 559 /* 560 * Initialize our zone, taking the user's requested size or 561 * estimating the number we need based on the number of pages 562 * in the system. 563 */ 564 n = maxswzone != 0 ? maxswzone / sizeof(struct swblk) : 565 vm_cnt.v_page_count / 2; 566 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, 567 pctrie_zone_init, NULL, UMA_ALIGN_PTR, UMA_ZONE_VM); 568 if (swpctrie_zone == NULL) 569 panic("failed to create swap pctrie zone."); 570 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, 571 NULL, NULL, _Alignof(struct swblk) - 1, UMA_ZONE_VM); 572 if (swblk_zone == NULL) 573 panic("failed to create swap blk zone."); 574 n2 = n; 575 do { 576 if (uma_zone_reserve_kva(swblk_zone, n)) 577 break; 578 /* 579 * if the allocation failed, try a zone two thirds the 580 * size of the previous attempt. 581 */ 582 n -= ((n + 2) / 3); 583 } while (n > 0); 584 585 /* 586 * Often uma_zone_reserve_kva() cannot reserve exactly the 587 * requested size. Account for the difference when 588 * calculating swap_maxpages. 589 */ 590 n = uma_zone_get_max(swblk_zone); 591 592 if (n < n2) 593 printf("Swap blk zone entries changed from %lu to %lu.\n", 594 n2, n); 595 /* absolute maximum we can handle assuming 100% efficiency */ 596 swap_maxpages = n * SWAP_META_PAGES; 597 swzone = n * sizeof(struct swblk); 598 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 599 printf("Cannot reserve swap pctrie zone, " 600 "reduce kern.maxswzone.\n"); 601 } 602 603 static vm_object_t 604 swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size, 605 vm_ooffset_t offset) 606 { 607 vm_object_t object; 608 609 if (cred != NULL) { 610 if (!swap_reserve_by_cred(size, cred)) 611 return (NULL); 612 crhold(cred); 613 } 614 615 /* 616 * The un_pager.swp.swp_blks trie is initialized by 617 * vm_object_allocate() to ensure the correct order of 618 * visibility to other threads. 619 */ 620 object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset + 621 PAGE_MASK + size)); 622 623 object->un_pager.swp.writemappings = 0; 624 object->handle = handle; 625 if (cred != NULL) { 626 object->cred = cred; 627 object->charge = size; 628 } 629 return (object); 630 } 631 632 /* 633 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 634 * its metadata structures. 635 * 636 * This routine is called from the mmap and fork code to create a new 637 * OBJT_SWAP object. 638 * 639 * This routine must ensure that no live duplicate is created for 640 * the named object request, which is protected against by 641 * holding the sw_alloc_sx lock in case handle != NULL. 642 */ 643 static vm_object_t 644 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 645 vm_ooffset_t offset, struct ucred *cred) 646 { 647 vm_object_t object; 648 649 if (handle != NULL) { 650 /* 651 * Reference existing named region or allocate new one. There 652 * should not be a race here against swp_pager_meta_build() 653 * as called from vm_page_remove() in regards to the lookup 654 * of the handle. 655 */ 656 sx_xlock(&sw_alloc_sx); 657 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 658 if (object == NULL) { 659 object = swap_pager_alloc_init(handle, cred, size, 660 offset); 661 if (object != NULL) { 662 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 663 object, pager_object_list); 664 } 665 } 666 sx_xunlock(&sw_alloc_sx); 667 } else { 668 object = swap_pager_alloc_init(handle, cred, size, offset); 669 } 670 return (object); 671 } 672 673 /* 674 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 675 * 676 * The swap backing for the object is destroyed. The code is 677 * designed such that we can reinstantiate it later, but this 678 * routine is typically called only when the entire object is 679 * about to be destroyed. 680 * 681 * The object must be locked. 682 */ 683 static void 684 swap_pager_dealloc(vm_object_t object) 685 { 686 687 VM_OBJECT_ASSERT_WLOCKED(object); 688 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 689 690 /* 691 * Remove from list right away so lookups will fail if we block for 692 * pageout completion. 693 */ 694 if (object->handle != NULL) { 695 VM_OBJECT_WUNLOCK(object); 696 sx_xlock(&sw_alloc_sx); 697 TAILQ_REMOVE(NOBJLIST(object->handle), object, 698 pager_object_list); 699 sx_xunlock(&sw_alloc_sx); 700 VM_OBJECT_WLOCK(object); 701 } 702 703 vm_object_pip_wait(object, "swpdea"); 704 705 /* 706 * Free all remaining metadata. We only bother to free it from 707 * the swap meta data. We do not attempt to free swapblk's still 708 * associated with vm_page_t's for this object. We do not care 709 * if paging is still in progress on some objects. 710 */ 711 swp_pager_meta_free_all(object); 712 object->handle = NULL; 713 object->type = OBJT_DEAD; 714 } 715 716 /************************************************************************ 717 * SWAP PAGER BITMAP ROUTINES * 718 ************************************************************************/ 719 720 /* 721 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 722 * 723 * Allocate swap for up to the requested number of pages, and at 724 * least a minimum number of pages. The starting swap block number 725 * (a page index) is returned or SWAPBLK_NONE if the allocation 726 * failed. 727 * 728 * Also has the side effect of advising that somebody made a mistake 729 * when they configured swap and didn't configure enough. 730 * 731 * This routine may not sleep. 732 * 733 * We allocate in round-robin fashion from the configured devices. 734 */ 735 static daddr_t 736 swp_pager_getswapspace(int *io_npages, int limit) 737 { 738 daddr_t blk; 739 struct swdevt *sp; 740 int mpages, npages; 741 742 blk = SWAPBLK_NONE; 743 mpages = *io_npages; 744 npages = imin(BLIST_MAX_ALLOC, mpages); 745 mtx_lock(&sw_dev_mtx); 746 sp = swdevhd; 747 while (!TAILQ_EMPTY(&swtailq)) { 748 if (sp == NULL) 749 sp = TAILQ_FIRST(&swtailq); 750 if ((sp->sw_flags & SW_CLOSING) == 0) 751 blk = blist_alloc(sp->sw_blist, &npages, mpages); 752 if (blk != SWAPBLK_NONE) 753 break; 754 sp = TAILQ_NEXT(sp, sw_list); 755 if (swdevhd == sp) { 756 if (npages <= limit) 757 break; 758 mpages = npages - 1; 759 npages >>= 1; 760 } 761 } 762 if (blk != SWAPBLK_NONE) { 763 *io_npages = npages; 764 blk += sp->sw_first; 765 sp->sw_used += npages; 766 swap_pager_avail -= npages; 767 swp_sizecheck(); 768 swdevhd = TAILQ_NEXT(sp, sw_list); 769 } else { 770 if (swap_pager_full != 2) { 771 printf("swp_pager_getswapspace(%d): failed\n", 772 *io_npages); 773 swap_pager_full = 2; 774 swap_pager_almost_full = 1; 775 } 776 swdevhd = NULL; 777 } 778 mtx_unlock(&sw_dev_mtx); 779 return (blk); 780 } 781 782 static bool 783 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 784 { 785 786 return (blk >= sp->sw_first && blk < sp->sw_end); 787 } 788 789 static void 790 swp_pager_strategy(struct buf *bp) 791 { 792 struct swdevt *sp; 793 794 mtx_lock(&sw_dev_mtx); 795 TAILQ_FOREACH(sp, &swtailq, sw_list) { 796 if (swp_pager_isondev(bp->b_blkno, sp)) { 797 mtx_unlock(&sw_dev_mtx); 798 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 799 unmapped_buf_allowed) { 800 bp->b_data = unmapped_buf; 801 bp->b_offset = 0; 802 } else { 803 pmap_qenter((vm_offset_t)bp->b_data, 804 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 805 } 806 sp->sw_strategy(bp, sp); 807 return; 808 } 809 } 810 panic("Swapdev not found"); 811 } 812 813 814 /* 815 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 816 * 817 * This routine returns the specified swap blocks back to the bitmap. 818 * 819 * This routine may not sleep. 820 */ 821 static void 822 swp_pager_freeswapspace(daddr_t blk, daddr_t npages) 823 { 824 struct swdevt *sp; 825 826 if (npages == 0) 827 return; 828 mtx_lock(&sw_dev_mtx); 829 TAILQ_FOREACH(sp, &swtailq, sw_list) { 830 if (swp_pager_isondev(blk, sp)) { 831 sp->sw_used -= npages; 832 /* 833 * If we are attempting to stop swapping on 834 * this device, we don't want to mark any 835 * blocks free lest they be reused. 836 */ 837 if ((sp->sw_flags & SW_CLOSING) == 0) { 838 blist_free(sp->sw_blist, blk - sp->sw_first, 839 npages); 840 swap_pager_avail += npages; 841 swp_sizecheck(); 842 } 843 mtx_unlock(&sw_dev_mtx); 844 return; 845 } 846 } 847 panic("Swapdev not found"); 848 } 849 850 /* 851 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 852 */ 853 static int 854 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 855 { 856 struct sbuf sbuf; 857 struct swdevt *sp; 858 const char *devname; 859 int error; 860 861 error = sysctl_wire_old_buffer(req, 0); 862 if (error != 0) 863 return (error); 864 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 865 mtx_lock(&sw_dev_mtx); 866 TAILQ_FOREACH(sp, &swtailq, sw_list) { 867 if (vn_isdisk(sp->sw_vp, NULL)) 868 devname = devtoname(sp->sw_vp->v_rdev); 869 else 870 devname = "[file]"; 871 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 872 blist_stats(sp->sw_blist, &sbuf); 873 } 874 mtx_unlock(&sw_dev_mtx); 875 error = sbuf_finish(&sbuf); 876 sbuf_delete(&sbuf); 877 return (error); 878 } 879 880 /* 881 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 882 * range within an object. 883 * 884 * This is a globally accessible routine. 885 * 886 * This routine removes swapblk assignments from swap metadata. 887 * 888 * The external callers of this routine typically have already destroyed 889 * or renamed vm_page_t's associated with this range in the object so 890 * we should be ok. 891 * 892 * The object must be locked. 893 */ 894 void 895 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 896 { 897 898 swp_pager_meta_free(object, start, size); 899 } 900 901 /* 902 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 903 * 904 * Assigns swap blocks to the specified range within the object. The 905 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 906 * 907 * Returns 0 on success, -1 on failure. 908 */ 909 int 910 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 911 { 912 daddr_t addr, blk, n_free, s_free; 913 int i, j, n; 914 915 swp_pager_init_freerange(&s_free, &n_free); 916 VM_OBJECT_WLOCK(object); 917 for (i = 0; i < size; i += n) { 918 n = size - i; 919 blk = swp_pager_getswapspace(&n, 1); 920 if (blk == SWAPBLK_NONE) { 921 swp_pager_meta_free(object, start, i); 922 VM_OBJECT_WUNLOCK(object); 923 return (-1); 924 } 925 for (j = 0; j < n; ++j) { 926 addr = swp_pager_meta_build(object, 927 start + i + j, blk + j); 928 if (addr != SWAPBLK_NONE) 929 swp_pager_update_freerange(&s_free, &n_free, 930 addr); 931 } 932 } 933 swp_pager_freeswapspace(s_free, n_free); 934 VM_OBJECT_WUNLOCK(object); 935 return (0); 936 } 937 938 static bool 939 swp_pager_xfer_source(vm_object_t srcobject, vm_object_t dstobject, 940 vm_pindex_t pindex, daddr_t addr) 941 { 942 daddr_t dstaddr; 943 944 if (swp_pager_meta_ctl(dstobject, pindex, 0) != SWAPBLK_NONE) { 945 /* Caller should destroy the source block. */ 946 return (false); 947 } 948 949 /* 950 * Destination has no swapblk and is not resident, transfer source. 951 * swp_pager_meta_build() can sleep. 952 */ 953 vm_object_pip_add(srcobject, 1); 954 VM_OBJECT_WUNLOCK(srcobject); 955 vm_object_pip_add(dstobject, 1); 956 dstaddr = swp_pager_meta_build(dstobject, pindex, addr); 957 KASSERT(dstaddr == SWAPBLK_NONE, 958 ("Unexpected destination swapblk")); 959 vm_object_pip_wakeup(dstobject); 960 VM_OBJECT_WLOCK(srcobject); 961 vm_object_pip_wakeup(srcobject); 962 return (true); 963 } 964 965 /* 966 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 967 * and destroy the source. 968 * 969 * Copy any valid swapblks from the source to the destination. In 970 * cases where both the source and destination have a valid swapblk, 971 * we keep the destination's. 972 * 973 * This routine is allowed to sleep. It may sleep allocating metadata 974 * indirectly through swp_pager_meta_build() or if paging is still in 975 * progress on the source. 976 * 977 * The source object contains no vm_page_t's (which is just as well) 978 * 979 * The source object is of type OBJT_SWAP. 980 * 981 * The source and destination objects must be locked. 982 * Both object locks may temporarily be released. 983 */ 984 void 985 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 986 vm_pindex_t offset, int destroysource) 987 { 988 989 VM_OBJECT_ASSERT_WLOCKED(srcobject); 990 VM_OBJECT_ASSERT_WLOCKED(dstobject); 991 992 /* 993 * If destroysource is set, we remove the source object from the 994 * swap_pager internal queue now. 995 */ 996 if (destroysource && srcobject->handle != NULL) { 997 vm_object_pip_add(srcobject, 1); 998 VM_OBJECT_WUNLOCK(srcobject); 999 vm_object_pip_add(dstobject, 1); 1000 VM_OBJECT_WUNLOCK(dstobject); 1001 sx_xlock(&sw_alloc_sx); 1002 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 1003 pager_object_list); 1004 sx_xunlock(&sw_alloc_sx); 1005 VM_OBJECT_WLOCK(dstobject); 1006 vm_object_pip_wakeup(dstobject); 1007 VM_OBJECT_WLOCK(srcobject); 1008 vm_object_pip_wakeup(srcobject); 1009 } 1010 1011 /* 1012 * Transfer source to destination. 1013 */ 1014 swp_pager_meta_transfer(srcobject, dstobject, offset, dstobject->size); 1015 1016 /* 1017 * Free left over swap blocks in source. 1018 * 1019 * We have to revert the type to OBJT_DEFAULT so we do not accidentally 1020 * double-remove the object from the swap queues. 1021 */ 1022 if (destroysource) { 1023 swp_pager_meta_free_all(srcobject); 1024 /* 1025 * Reverting the type is not necessary, the caller is going 1026 * to destroy srcobject directly, but I'm doing it here 1027 * for consistency since we've removed the object from its 1028 * queues. 1029 */ 1030 srcobject->type = OBJT_DEFAULT; 1031 } 1032 } 1033 1034 /* 1035 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1036 * the requested page. 1037 * 1038 * We determine whether good backing store exists for the requested 1039 * page and return TRUE if it does, FALSE if it doesn't. 1040 * 1041 * If TRUE, we also try to determine how much valid, contiguous backing 1042 * store exists before and after the requested page. 1043 */ 1044 static boolean_t 1045 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1046 int *after) 1047 { 1048 daddr_t blk, blk0; 1049 int i; 1050 1051 VM_OBJECT_ASSERT_LOCKED(object); 1052 1053 /* 1054 * do we have good backing store at the requested index ? 1055 */ 1056 blk0 = swp_pager_meta_ctl(object, pindex, 0); 1057 if (blk0 == SWAPBLK_NONE) { 1058 if (before) 1059 *before = 0; 1060 if (after) 1061 *after = 0; 1062 return (FALSE); 1063 } 1064 1065 /* 1066 * find backwards-looking contiguous good backing store 1067 */ 1068 if (before != NULL) { 1069 for (i = 1; i < SWB_NPAGES; i++) { 1070 if (i > pindex) 1071 break; 1072 blk = swp_pager_meta_ctl(object, pindex - i, 0); 1073 if (blk != blk0 - i) 1074 break; 1075 } 1076 *before = i - 1; 1077 } 1078 1079 /* 1080 * find forward-looking contiguous good backing store 1081 */ 1082 if (after != NULL) { 1083 for (i = 1; i < SWB_NPAGES; i++) { 1084 blk = swp_pager_meta_ctl(object, pindex + i, 0); 1085 if (blk != blk0 + i) 1086 break; 1087 } 1088 *after = i - 1; 1089 } 1090 return (TRUE); 1091 } 1092 1093 /* 1094 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1095 * 1096 * This removes any associated swap backing store, whether valid or 1097 * not, from the page. 1098 * 1099 * This routine is typically called when a page is made dirty, at 1100 * which point any associated swap can be freed. MADV_FREE also 1101 * calls us in a special-case situation 1102 * 1103 * NOTE!!! If the page is clean and the swap was valid, the caller 1104 * should make the page dirty before calling this routine. This routine 1105 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1106 * depends on it. 1107 * 1108 * This routine may not sleep. 1109 * 1110 * The object containing the page must be locked. 1111 */ 1112 static void 1113 swap_pager_unswapped(vm_page_t m) 1114 { 1115 daddr_t srcaddr; 1116 1117 srcaddr = swp_pager_meta_ctl(m->object, m->pindex, SWM_POP); 1118 if (srcaddr != SWAPBLK_NONE) 1119 swp_pager_freeswapspace(srcaddr, 1); 1120 } 1121 1122 /* 1123 * swap_pager_getpages() - bring pages in from swap 1124 * 1125 * Attempt to page in the pages in array "ma" of length "count". The 1126 * caller may optionally specify that additional pages preceding and 1127 * succeeding the specified range be paged in. The number of such pages 1128 * is returned in the "rbehind" and "rahead" parameters, and they will 1129 * be in the inactive queue upon return. 1130 * 1131 * The pages in "ma" must be busied and will remain busied upon return. 1132 */ 1133 static int 1134 swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count, int *rbehind, 1135 int *rahead) 1136 { 1137 struct buf *bp; 1138 vm_page_t bm, mpred, msucc, p; 1139 vm_pindex_t pindex; 1140 daddr_t blk; 1141 int i, maxahead, maxbehind, reqcount; 1142 1143 reqcount = count; 1144 1145 /* 1146 * Determine the final number of read-behind pages and 1147 * allocate them BEFORE releasing the object lock. Otherwise, 1148 * there can be a problematic race with vm_object_split(). 1149 * Specifically, vm_object_split() might first transfer pages 1150 * that precede ma[0] in the current object to a new object, 1151 * and then this function incorrectly recreates those pages as 1152 * read-behind pages in the current object. 1153 */ 1154 if (!swap_pager_haspage(object, ma[0]->pindex, &maxbehind, &maxahead)) 1155 return (VM_PAGER_FAIL); 1156 1157 /* 1158 * Clip the readahead and readbehind ranges to exclude resident pages. 1159 */ 1160 if (rahead != NULL) { 1161 KASSERT(reqcount - 1 <= maxahead, 1162 ("page count %d extends beyond swap block", reqcount)); 1163 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1164 pindex = ma[reqcount - 1]->pindex; 1165 msucc = TAILQ_NEXT(ma[reqcount - 1], listq); 1166 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1167 *rahead = msucc->pindex - pindex - 1; 1168 } 1169 if (rbehind != NULL) { 1170 *rbehind = imin(*rbehind, maxbehind); 1171 pindex = ma[0]->pindex; 1172 mpred = TAILQ_PREV(ma[0], pglist, listq); 1173 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1174 *rbehind = pindex - mpred->pindex - 1; 1175 } 1176 1177 bm = ma[0]; 1178 for (i = 0; i < count; i++) 1179 ma[i]->oflags |= VPO_SWAPINPROG; 1180 1181 /* 1182 * Allocate readahead and readbehind pages. 1183 */ 1184 if (rbehind != NULL) { 1185 for (i = 1; i <= *rbehind; i++) { 1186 p = vm_page_alloc(object, ma[0]->pindex - i, 1187 VM_ALLOC_NORMAL); 1188 if (p == NULL) 1189 break; 1190 p->oflags |= VPO_SWAPINPROG; 1191 bm = p; 1192 } 1193 *rbehind = i - 1; 1194 } 1195 if (rahead != NULL) { 1196 for (i = 0; i < *rahead; i++) { 1197 p = vm_page_alloc(object, 1198 ma[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1199 if (p == NULL) 1200 break; 1201 p->oflags |= VPO_SWAPINPROG; 1202 } 1203 *rahead = i; 1204 } 1205 if (rbehind != NULL) 1206 count += *rbehind; 1207 if (rahead != NULL) 1208 count += *rahead; 1209 1210 vm_object_pip_add(object, count); 1211 1212 pindex = bm->pindex; 1213 blk = swp_pager_meta_ctl(object, pindex, 0); 1214 KASSERT(blk != SWAPBLK_NONE, 1215 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1216 1217 VM_OBJECT_WUNLOCK(object); 1218 bp = uma_zalloc(swrbuf_zone, M_WAITOK); 1219 /* Pages cannot leave the object while busy. */ 1220 for (i = 0, p = bm; i < count; i++, p = TAILQ_NEXT(p, listq)) { 1221 MPASS(p->pindex == bm->pindex + i); 1222 bp->b_pages[i] = p; 1223 } 1224 1225 bp->b_flags |= B_PAGING; 1226 bp->b_iocmd = BIO_READ; 1227 bp->b_iodone = swp_pager_async_iodone; 1228 bp->b_rcred = crhold(thread0.td_ucred); 1229 bp->b_wcred = crhold(thread0.td_ucred); 1230 bp->b_blkno = blk; 1231 bp->b_bcount = PAGE_SIZE * count; 1232 bp->b_bufsize = PAGE_SIZE * count; 1233 bp->b_npages = count; 1234 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1235 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1236 1237 VM_CNT_INC(v_swapin); 1238 VM_CNT_ADD(v_swappgsin, count); 1239 1240 /* 1241 * perform the I/O. NOTE!!! bp cannot be considered valid after 1242 * this point because we automatically release it on completion. 1243 * Instead, we look at the one page we are interested in which we 1244 * still hold a lock on even through the I/O completion. 1245 * 1246 * The other pages in our ma[] array are also released on completion, 1247 * so we cannot assume they are valid anymore either. 1248 * 1249 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1250 */ 1251 BUF_KERNPROC(bp); 1252 swp_pager_strategy(bp); 1253 1254 /* 1255 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1256 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1257 * is set in the metadata for each page in the request. 1258 */ 1259 VM_OBJECT_WLOCK(object); 1260 while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) { 1261 ma[0]->oflags |= VPO_SWAPSLEEP; 1262 VM_CNT_INC(v_intrans); 1263 if (VM_OBJECT_SLEEP(object, &object->handle, PSWP, 1264 "swread", hz * 20)) { 1265 printf( 1266 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1267 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1268 } 1269 } 1270 1271 /* 1272 * If we had an unrecoverable read error pages will not be valid. 1273 */ 1274 for (i = 0; i < reqcount; i++) 1275 if (ma[i]->valid != VM_PAGE_BITS_ALL) 1276 return (VM_PAGER_ERROR); 1277 1278 return (VM_PAGER_OK); 1279 1280 /* 1281 * A final note: in a low swap situation, we cannot deallocate swap 1282 * and mark a page dirty here because the caller is likely to mark 1283 * the page clean when we return, causing the page to possibly revert 1284 * to all-zero's later. 1285 */ 1286 } 1287 1288 /* 1289 * swap_pager_getpages_async(): 1290 * 1291 * Right now this is emulation of asynchronous operation on top of 1292 * swap_pager_getpages(). 1293 */ 1294 static int 1295 swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count, 1296 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1297 { 1298 int r, error; 1299 1300 r = swap_pager_getpages(object, ma, count, rbehind, rahead); 1301 VM_OBJECT_WUNLOCK(object); 1302 switch (r) { 1303 case VM_PAGER_OK: 1304 error = 0; 1305 break; 1306 case VM_PAGER_ERROR: 1307 error = EIO; 1308 break; 1309 case VM_PAGER_FAIL: 1310 error = EINVAL; 1311 break; 1312 default: 1313 panic("unhandled swap_pager_getpages() error %d", r); 1314 } 1315 (iodone)(arg, ma, count, error); 1316 VM_OBJECT_WLOCK(object); 1317 1318 return (r); 1319 } 1320 1321 /* 1322 * swap_pager_putpages: 1323 * 1324 * Assign swap (if necessary) and initiate I/O on the specified pages. 1325 * 1326 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1327 * are automatically converted to SWAP objects. 1328 * 1329 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1330 * vm_page reservation system coupled with properly written VFS devices 1331 * should ensure that no low-memory deadlock occurs. This is an area 1332 * which needs work. 1333 * 1334 * The parent has N vm_object_pip_add() references prior to 1335 * calling us and will remove references for rtvals[] that are 1336 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1337 * completion. 1338 * 1339 * The parent has soft-busy'd the pages it passes us and will unbusy 1340 * those whose rtvals[] entry is not set to VM_PAGER_PEND on return. 1341 * We need to unbusy the rest on I/O completion. 1342 */ 1343 static void 1344 swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count, 1345 int flags, int *rtvals) 1346 { 1347 struct buf *bp; 1348 daddr_t addr, blk, n_free, s_free; 1349 vm_page_t mreq; 1350 int i, j, n; 1351 bool async; 1352 1353 KASSERT(count == 0 || ma[0]->object == object, 1354 ("%s: object mismatch %p/%p", 1355 __func__, object, ma[0]->object)); 1356 1357 /* 1358 * Step 1 1359 * 1360 * Turn object into OBJT_SWAP. Force sync if not a pageout process. 1361 */ 1362 if (object->type != OBJT_SWAP) { 1363 addr = swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1364 KASSERT(addr == SWAPBLK_NONE, 1365 ("unexpected object swap block")); 1366 } 1367 VM_OBJECT_WUNLOCK(object); 1368 async = curproc == pageproc && (flags & VM_PAGER_PUT_SYNC) == 0; 1369 swp_pager_init_freerange(&s_free, &n_free); 1370 1371 /* 1372 * Step 2 1373 * 1374 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1375 * The page is left dirty until the pageout operation completes 1376 * successfully. 1377 */ 1378 for (i = 0; i < count; i += n) { 1379 /* Maximum I/O size is limited by maximum swap block size. */ 1380 n = min(count - i, nsw_cluster_max); 1381 1382 /* Get a block of swap of size up to size n. */ 1383 blk = swp_pager_getswapspace(&n, 4); 1384 if (blk == SWAPBLK_NONE) { 1385 for (j = 0; j < n; ++j) 1386 rtvals[i + j] = VM_PAGER_FAIL; 1387 continue; 1388 } 1389 1390 /* 1391 * All I/O parameters have been satisfied. Build the I/O 1392 * request and assign the swap space. 1393 */ 1394 if (async) { 1395 mtx_lock(&swbuf_mtx); 1396 while (nsw_wcount_async == 0) 1397 msleep(&nsw_wcount_async, &swbuf_mtx, PVM, 1398 "swbufa", 0); 1399 nsw_wcount_async--; 1400 mtx_unlock(&swbuf_mtx); 1401 } 1402 bp = uma_zalloc(swwbuf_zone, M_WAITOK); 1403 if (async) 1404 bp->b_flags = B_ASYNC; 1405 bp->b_flags |= B_PAGING; 1406 bp->b_iocmd = BIO_WRITE; 1407 1408 bp->b_rcred = crhold(thread0.td_ucred); 1409 bp->b_wcred = crhold(thread0.td_ucred); 1410 bp->b_bcount = PAGE_SIZE * n; 1411 bp->b_bufsize = PAGE_SIZE * n; 1412 bp->b_blkno = blk; 1413 1414 VM_OBJECT_WLOCK(object); 1415 for (j = 0; j < n; ++j) { 1416 mreq = ma[i + j]; 1417 addr = swp_pager_meta_build(mreq->object, mreq->pindex, 1418 blk + j); 1419 if (addr != SWAPBLK_NONE) 1420 swp_pager_update_freerange(&s_free, &n_free, 1421 addr); 1422 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1423 mreq->oflags |= VPO_SWAPINPROG; 1424 bp->b_pages[j] = mreq; 1425 } 1426 VM_OBJECT_WUNLOCK(object); 1427 bp->b_npages = n; 1428 /* 1429 * Must set dirty range for NFS to work. 1430 */ 1431 bp->b_dirtyoff = 0; 1432 bp->b_dirtyend = bp->b_bcount; 1433 1434 VM_CNT_INC(v_swapout); 1435 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1436 1437 /* 1438 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1439 * can call the async completion routine at the end of a 1440 * synchronous I/O operation. Otherwise, our caller would 1441 * perform duplicate unbusy and wakeup operations on the page 1442 * and object, respectively. 1443 */ 1444 for (j = 0; j < n; j++) 1445 rtvals[i + j] = VM_PAGER_PEND; 1446 1447 /* 1448 * asynchronous 1449 * 1450 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1451 */ 1452 if (async) { 1453 bp->b_iodone = swp_pager_async_iodone; 1454 BUF_KERNPROC(bp); 1455 swp_pager_strategy(bp); 1456 continue; 1457 } 1458 1459 /* 1460 * synchronous 1461 * 1462 * NOTE: b_blkno is destroyed by the call to swapdev_strategy. 1463 */ 1464 bp->b_iodone = bdone; 1465 swp_pager_strategy(bp); 1466 1467 /* 1468 * Wait for the sync I/O to complete. 1469 */ 1470 bwait(bp, PVM, "swwrt"); 1471 1472 /* 1473 * Now that we are through with the bp, we can call the 1474 * normal async completion, which frees everything up. 1475 */ 1476 swp_pager_async_iodone(bp); 1477 } 1478 swp_pager_freeswapspace(s_free, n_free); 1479 VM_OBJECT_WLOCK(object); 1480 } 1481 1482 /* 1483 * swp_pager_async_iodone: 1484 * 1485 * Completion routine for asynchronous reads and writes from/to swap. 1486 * Also called manually by synchronous code to finish up a bp. 1487 * 1488 * This routine may not sleep. 1489 */ 1490 static void 1491 swp_pager_async_iodone(struct buf *bp) 1492 { 1493 int i; 1494 vm_object_t object = NULL; 1495 1496 /* 1497 * Report error - unless we ran out of memory, in which case 1498 * we've already logged it in swapgeom_strategy(). 1499 */ 1500 if (bp->b_ioflags & BIO_ERROR && bp->b_error != ENOMEM) { 1501 printf( 1502 "swap_pager: I/O error - %s failed; blkno %ld," 1503 "size %ld, error %d\n", 1504 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1505 (long)bp->b_blkno, 1506 (long)bp->b_bcount, 1507 bp->b_error 1508 ); 1509 } 1510 1511 /* 1512 * remove the mapping for kernel virtual 1513 */ 1514 if (buf_mapped(bp)) 1515 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1516 else 1517 bp->b_data = bp->b_kvabase; 1518 1519 if (bp->b_npages) { 1520 object = bp->b_pages[0]->object; 1521 VM_OBJECT_WLOCK(object); 1522 } 1523 1524 /* 1525 * cleanup pages. If an error occurs writing to swap, we are in 1526 * very serious trouble. If it happens to be a disk error, though, 1527 * we may be able to recover by reassigning the swap later on. So 1528 * in this case we remove the m->swapblk assignment for the page 1529 * but do not free it in the rlist. The errornous block(s) are thus 1530 * never reallocated as swap. Redirty the page and continue. 1531 */ 1532 for (i = 0; i < bp->b_npages; ++i) { 1533 vm_page_t m = bp->b_pages[i]; 1534 1535 m->oflags &= ~VPO_SWAPINPROG; 1536 if (m->oflags & VPO_SWAPSLEEP) { 1537 m->oflags &= ~VPO_SWAPSLEEP; 1538 wakeup(&object->handle); 1539 } 1540 1541 if (bp->b_ioflags & BIO_ERROR) { 1542 /* 1543 * If an error occurs I'd love to throw the swapblk 1544 * away without freeing it back to swapspace, so it 1545 * can never be used again. But I can't from an 1546 * interrupt. 1547 */ 1548 if (bp->b_iocmd == BIO_READ) { 1549 /* 1550 * NOTE: for reads, m->dirty will probably 1551 * be overridden by the original caller of 1552 * getpages so don't play cute tricks here. 1553 */ 1554 vm_page_invalid(m); 1555 } else { 1556 /* 1557 * If a write error occurs, reactivate page 1558 * so it doesn't clog the inactive list, 1559 * then finish the I/O. 1560 */ 1561 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1562 vm_page_lock(m); 1563 vm_page_activate(m); 1564 vm_page_unlock(m); 1565 vm_page_sunbusy(m); 1566 } 1567 } else if (bp->b_iocmd == BIO_READ) { 1568 /* 1569 * NOTE: for reads, m->dirty will probably be 1570 * overridden by the original caller of getpages so 1571 * we cannot set them in order to free the underlying 1572 * swap in a low-swap situation. I don't think we'd 1573 * want to do that anyway, but it was an optimization 1574 * that existed in the old swapper for a time before 1575 * it got ripped out due to precisely this problem. 1576 */ 1577 KASSERT(!pmap_page_is_mapped(m), 1578 ("swp_pager_async_iodone: page %p is mapped", m)); 1579 KASSERT(m->dirty == 0, 1580 ("swp_pager_async_iodone: page %p is dirty", m)); 1581 1582 vm_page_valid(m); 1583 if (i < bp->b_pgbefore || 1584 i >= bp->b_npages - bp->b_pgafter) 1585 vm_page_readahead_finish(m); 1586 } else { 1587 /* 1588 * For write success, clear the dirty 1589 * status, then finish the I/O ( which decrements the 1590 * busy count and possibly wakes waiter's up ). 1591 * A page is only written to swap after a period of 1592 * inactivity. Therefore, we do not expect it to be 1593 * reused. 1594 */ 1595 KASSERT(!pmap_page_is_write_mapped(m), 1596 ("swp_pager_async_iodone: page %p is not write" 1597 " protected", m)); 1598 vm_page_undirty(m); 1599 vm_page_lock(m); 1600 vm_page_deactivate_noreuse(m); 1601 vm_page_unlock(m); 1602 vm_page_sunbusy(m); 1603 } 1604 } 1605 1606 /* 1607 * adjust pip. NOTE: the original parent may still have its own 1608 * pip refs on the object. 1609 */ 1610 if (object != NULL) { 1611 vm_object_pip_wakeupn(object, bp->b_npages); 1612 VM_OBJECT_WUNLOCK(object); 1613 } 1614 1615 /* 1616 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1617 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1618 * trigger a KASSERT in relpbuf(). 1619 */ 1620 if (bp->b_vp) { 1621 bp->b_vp = NULL; 1622 bp->b_bufobj = NULL; 1623 } 1624 /* 1625 * release the physical I/O buffer 1626 */ 1627 if (bp->b_flags & B_ASYNC) { 1628 mtx_lock(&swbuf_mtx); 1629 if (++nsw_wcount_async == 1) 1630 wakeup(&nsw_wcount_async); 1631 mtx_unlock(&swbuf_mtx); 1632 } 1633 uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp); 1634 } 1635 1636 int 1637 swap_pager_nswapdev(void) 1638 { 1639 1640 return (nswapdev); 1641 } 1642 1643 static void 1644 swp_pager_force_dirty(vm_page_t m) 1645 { 1646 1647 vm_page_dirty(m); 1648 #ifdef INVARIANTS 1649 vm_page_lock(m); 1650 if (!vm_page_wired(m) && m->queue == PQ_NONE) 1651 panic("page %p is neither wired nor queued", m); 1652 vm_page_unlock(m); 1653 #endif 1654 vm_page_xunbusy(m); 1655 swap_pager_unswapped(m); 1656 } 1657 1658 static void 1659 swp_pager_force_launder(vm_page_t m) 1660 { 1661 1662 vm_page_dirty(m); 1663 vm_page_lock(m); 1664 vm_page_launder(m); 1665 vm_page_unlock(m); 1666 vm_page_xunbusy(m); 1667 swap_pager_unswapped(m); 1668 } 1669 1670 /* 1671 * SWP_PAGER_FORCE_PAGEIN() - force swap blocks to be paged in 1672 * 1673 * This routine dissociates pages starting at the given index within an 1674 * object from their backing store, paging them in if they do not reside 1675 * in memory. Pages that are paged in are marked dirty and placed in the 1676 * laundry queue. Pages are marked dirty because they no longer have 1677 * backing store. They are placed in the laundry queue because they have 1678 * not been accessed recently. Otherwise, they would already reside in 1679 * memory. 1680 */ 1681 static void 1682 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex, int npages) 1683 { 1684 vm_page_t ma[npages]; 1685 int i, j; 1686 1687 KASSERT(npages > 0, ("%s: No pages", __func__)); 1688 KASSERT(npages <= MAXPHYS / PAGE_SIZE, 1689 ("%s: Too many pages: %d", __func__, npages)); 1690 vm_object_pip_add(object, npages); 1691 vm_page_grab_pages(object, pindex, VM_ALLOC_NORMAL, ma, npages); 1692 for (i = j = 0;; i++) { 1693 /* Count nonresident pages, to page-in all at once. */ 1694 if (i < npages && ma[i]->valid != VM_PAGE_BITS_ALL) 1695 continue; 1696 if (j < i) { 1697 /* Page-in nonresident pages. Mark for laundering. */ 1698 if (swap_pager_getpages(object, &ma[j], i - j, NULL, 1699 NULL) != VM_PAGER_OK) 1700 panic("%s: read from swap failed", __func__); 1701 do { 1702 swp_pager_force_launder(ma[j]); 1703 } while (++j < i); 1704 } 1705 if (i == npages) 1706 break; 1707 /* Mark dirty a resident page. */ 1708 swp_pager_force_dirty(ma[j++]); 1709 } 1710 vm_object_pip_wakeupn(object, npages); 1711 } 1712 1713 /* 1714 * swap_pager_swapoff_object: 1715 * 1716 * Page in all of the pages that have been paged out for an object 1717 * to a swap device. 1718 */ 1719 static void 1720 swap_pager_swapoff_object(struct swdevt *sp, vm_object_t object) 1721 { 1722 struct swblk *sb; 1723 vm_pindex_t pi, s_pindex; 1724 daddr_t blk, n_blks, s_blk; 1725 int i; 1726 1727 n_blks = 0; 1728 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1729 &object->un_pager.swp.swp_blks, pi)) != NULL; ) { 1730 for (i = 0; i < SWAP_META_PAGES; i++) { 1731 blk = sb->d[i]; 1732 if (!swp_pager_isondev(blk, sp)) 1733 blk = SWAPBLK_NONE; 1734 1735 /* 1736 * If there are no blocks/pages accumulated, start a new 1737 * accumulation here. 1738 */ 1739 if (n_blks == 0) { 1740 if (blk != SWAPBLK_NONE) { 1741 s_blk = blk; 1742 s_pindex = sb->p + i; 1743 n_blks = 1; 1744 } 1745 continue; 1746 } 1747 1748 /* 1749 * If the accumulation can be extended without breaking 1750 * the sequence of consecutive blocks and pages that 1751 * swp_pager_force_pagein() depends on, do so. 1752 */ 1753 if (n_blks < MAXPHYS / PAGE_SIZE && 1754 s_blk + n_blks == blk && 1755 s_pindex + n_blks == sb->p + i) { 1756 ++n_blks; 1757 continue; 1758 } 1759 1760 /* 1761 * The sequence of consecutive blocks and pages cannot 1762 * be extended, so page them all in here. Then, 1763 * because doing so involves releasing and reacquiring 1764 * a lock that protects the swap block pctrie, do not 1765 * rely on the current swap block. Break this loop and 1766 * re-fetch the same pindex from the pctrie again. 1767 */ 1768 swp_pager_force_pagein(object, s_pindex, n_blks); 1769 n_blks = 0; 1770 break; 1771 } 1772 if (i == SWAP_META_PAGES) 1773 pi = sb->p + SWAP_META_PAGES; 1774 } 1775 if (n_blks > 0) 1776 swp_pager_force_pagein(object, s_pindex, n_blks); 1777 } 1778 1779 /* 1780 * swap_pager_swapoff: 1781 * 1782 * Page in all of the pages that have been paged out to the 1783 * given device. The corresponding blocks in the bitmap must be 1784 * marked as allocated and the device must be flagged SW_CLOSING. 1785 * There may be no processes swapped out to the device. 1786 * 1787 * This routine may block. 1788 */ 1789 static void 1790 swap_pager_swapoff(struct swdevt *sp) 1791 { 1792 vm_object_t object; 1793 int retries; 1794 1795 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 1796 1797 retries = 0; 1798 full_rescan: 1799 mtx_lock(&vm_object_list_mtx); 1800 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1801 if (object->type != OBJT_SWAP) 1802 continue; 1803 mtx_unlock(&vm_object_list_mtx); 1804 /* Depends on type-stability. */ 1805 VM_OBJECT_WLOCK(object); 1806 1807 /* 1808 * Dead objects are eventually terminated on their own. 1809 */ 1810 if ((object->flags & OBJ_DEAD) != 0) 1811 goto next_obj; 1812 1813 /* 1814 * Sync with fences placed after pctrie 1815 * initialization. We must not access pctrie below 1816 * unless we checked that our object is swap and not 1817 * dead. 1818 */ 1819 atomic_thread_fence_acq(); 1820 if (object->type != OBJT_SWAP) 1821 goto next_obj; 1822 1823 swap_pager_swapoff_object(sp, object); 1824 next_obj: 1825 VM_OBJECT_WUNLOCK(object); 1826 mtx_lock(&vm_object_list_mtx); 1827 } 1828 mtx_unlock(&vm_object_list_mtx); 1829 1830 if (sp->sw_used) { 1831 /* 1832 * Objects may be locked or paging to the device being 1833 * removed, so we will miss their pages and need to 1834 * make another pass. We have marked this device as 1835 * SW_CLOSING, so the activity should finish soon. 1836 */ 1837 retries++; 1838 if (retries > 100) { 1839 panic("swapoff: failed to locate %d swap blocks", 1840 sp->sw_used); 1841 } 1842 pause("swpoff", hz / 20); 1843 goto full_rescan; 1844 } 1845 EVENTHANDLER_INVOKE(swapoff, sp); 1846 } 1847 1848 /************************************************************************ 1849 * SWAP META DATA * 1850 ************************************************************************ 1851 * 1852 * These routines manipulate the swap metadata stored in the 1853 * OBJT_SWAP object. 1854 * 1855 * Swap metadata is implemented with a global hash and not directly 1856 * linked into the object. Instead the object simply contains 1857 * appropriate tracking counters. 1858 */ 1859 1860 /* 1861 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? 1862 */ 1863 static bool 1864 swp_pager_swblk_empty(struct swblk *sb, int start, int limit) 1865 { 1866 int i; 1867 1868 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); 1869 for (i = start; i < limit; i++) { 1870 if (sb->d[i] != SWAPBLK_NONE) 1871 return (false); 1872 } 1873 return (true); 1874 } 1875 1876 /* 1877 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1878 * 1879 * We first convert the object to a swap object if it is a default 1880 * object. 1881 * 1882 * The specified swapblk is added to the object's swap metadata. If 1883 * the swapblk is not valid, it is freed instead. Any previously 1884 * assigned swapblk is returned. 1885 */ 1886 static daddr_t 1887 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1888 { 1889 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 1890 struct swblk *sb, *sb1; 1891 vm_pindex_t modpi, rdpi; 1892 daddr_t prev_swapblk; 1893 int error, i; 1894 1895 VM_OBJECT_ASSERT_WLOCKED(object); 1896 1897 /* 1898 * Convert default object to swap object if necessary 1899 */ 1900 if (object->type != OBJT_SWAP) { 1901 pctrie_init(&object->un_pager.swp.swp_blks); 1902 1903 /* 1904 * Ensure that swap_pager_swapoff()'s iteration over 1905 * object_list does not see a garbage pctrie. 1906 */ 1907 atomic_thread_fence_rel(); 1908 1909 object->type = OBJT_SWAP; 1910 object->un_pager.swp.writemappings = 0; 1911 KASSERT(object->handle == NULL, ("default pager with handle")); 1912 } 1913 1914 rdpi = rounddown(pindex, SWAP_META_PAGES); 1915 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi); 1916 if (sb == NULL) { 1917 if (swapblk == SWAPBLK_NONE) 1918 return (SWAPBLK_NONE); 1919 for (;;) { 1920 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 1921 pageproc ? M_USE_RESERVE : 0)); 1922 if (sb != NULL) { 1923 sb->p = rdpi; 1924 for (i = 0; i < SWAP_META_PAGES; i++) 1925 sb->d[i] = SWAPBLK_NONE; 1926 if (atomic_cmpset_int(&swblk_zone_exhausted, 1927 1, 0)) 1928 printf("swblk zone ok\n"); 1929 break; 1930 } 1931 VM_OBJECT_WUNLOCK(object); 1932 if (uma_zone_exhausted(swblk_zone)) { 1933 if (atomic_cmpset_int(&swblk_zone_exhausted, 1934 0, 1)) 1935 printf("swap blk zone exhausted, " 1936 "increase kern.maxswzone\n"); 1937 vm_pageout_oom(VM_OOM_SWAPZ); 1938 pause("swzonxb", 10); 1939 } else 1940 uma_zwait(swblk_zone); 1941 VM_OBJECT_WLOCK(object); 1942 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 1943 rdpi); 1944 if (sb != NULL) 1945 /* 1946 * Somebody swapped out a nearby page, 1947 * allocating swblk at the rdpi index, 1948 * while we dropped the object lock. 1949 */ 1950 goto allocated; 1951 } 1952 for (;;) { 1953 error = SWAP_PCTRIE_INSERT( 1954 &object->un_pager.swp.swp_blks, sb); 1955 if (error == 0) { 1956 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1957 1, 0)) 1958 printf("swpctrie zone ok\n"); 1959 break; 1960 } 1961 VM_OBJECT_WUNLOCK(object); 1962 if (uma_zone_exhausted(swpctrie_zone)) { 1963 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1964 0, 1)) 1965 printf("swap pctrie zone exhausted, " 1966 "increase kern.maxswzone\n"); 1967 vm_pageout_oom(VM_OOM_SWAPZ); 1968 pause("swzonxp", 10); 1969 } else 1970 uma_zwait(swpctrie_zone); 1971 VM_OBJECT_WLOCK(object); 1972 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 1973 rdpi); 1974 if (sb1 != NULL) { 1975 uma_zfree(swblk_zone, sb); 1976 sb = sb1; 1977 goto allocated; 1978 } 1979 } 1980 } 1981 allocated: 1982 MPASS(sb->p == rdpi); 1983 1984 modpi = pindex % SWAP_META_PAGES; 1985 /* Return prior contents of metadata. */ 1986 prev_swapblk = sb->d[modpi]; 1987 /* Enter block into metadata. */ 1988 sb->d[modpi] = swapblk; 1989 1990 /* 1991 * Free the swblk if we end up with the empty page run. 1992 */ 1993 if (swapblk == SWAPBLK_NONE && 1994 swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 1995 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, rdpi); 1996 uma_zfree(swblk_zone, sb); 1997 } 1998 return (prev_swapblk); 1999 } 2000 2001 /* 2002 * SWP_PAGER_META_TRANSFER() - free a range of blocks in the srcobject's swap 2003 * metadata, or transfer it into dstobject. 2004 * 2005 * This routine will free swap metadata structures as they are cleaned 2006 * out. 2007 */ 2008 static void 2009 swp_pager_meta_transfer(vm_object_t srcobject, vm_object_t dstobject, 2010 vm_pindex_t pindex, vm_pindex_t count) 2011 { 2012 struct swblk *sb; 2013 daddr_t n_free, s_free; 2014 vm_pindex_t offset, last; 2015 int i, limit, start; 2016 2017 VM_OBJECT_ASSERT_WLOCKED(srcobject); 2018 if (srcobject->type != OBJT_SWAP || count == 0) 2019 return; 2020 2021 swp_pager_init_freerange(&s_free, &n_free); 2022 offset = pindex; 2023 last = pindex + count; 2024 for (;;) { 2025 sb = SWAP_PCTRIE_LOOKUP_GE(&srcobject->un_pager.swp.swp_blks, 2026 rounddown(pindex, SWAP_META_PAGES)); 2027 if (sb == NULL || sb->p >= last) 2028 break; 2029 start = pindex > sb->p ? pindex - sb->p : 0; 2030 limit = last - sb->p < SWAP_META_PAGES ? last - sb->p : 2031 SWAP_META_PAGES; 2032 for (i = start; i < limit; i++) { 2033 if (sb->d[i] == SWAPBLK_NONE) 2034 continue; 2035 if (dstobject == NULL || 2036 !swp_pager_xfer_source(srcobject, dstobject, 2037 sb->p + i - offset, sb->d[i])) { 2038 swp_pager_update_freerange(&s_free, &n_free, 2039 sb->d[i]); 2040 } 2041 sb->d[i] = SWAPBLK_NONE; 2042 } 2043 pindex = sb->p + SWAP_META_PAGES; 2044 if (swp_pager_swblk_empty(sb, 0, start) && 2045 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 2046 SWAP_PCTRIE_REMOVE(&srcobject->un_pager.swp.swp_blks, 2047 sb->p); 2048 uma_zfree(swblk_zone, sb); 2049 } 2050 } 2051 swp_pager_freeswapspace(s_free, n_free); 2052 } 2053 2054 /* 2055 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 2056 * 2057 * The requested range of blocks is freed, with any associated swap 2058 * returned to the swap bitmap. 2059 * 2060 * This routine will free swap metadata structures as they are cleaned 2061 * out. This routine does *NOT* operate on swap metadata associated 2062 * with resident pages. 2063 */ 2064 static void 2065 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count) 2066 { 2067 swp_pager_meta_transfer(object, NULL, pindex, count); 2068 } 2069 2070 /* 2071 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2072 * 2073 * This routine locates and destroys all swap metadata associated with 2074 * an object. 2075 */ 2076 static void 2077 swp_pager_meta_free_all(vm_object_t object) 2078 { 2079 struct swblk *sb; 2080 daddr_t n_free, s_free; 2081 vm_pindex_t pindex; 2082 int i; 2083 2084 VM_OBJECT_ASSERT_WLOCKED(object); 2085 if (object->type != OBJT_SWAP) 2086 return; 2087 2088 swp_pager_init_freerange(&s_free, &n_free); 2089 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 2090 &object->un_pager.swp.swp_blks, pindex)) != NULL;) { 2091 pindex = sb->p + SWAP_META_PAGES; 2092 for (i = 0; i < SWAP_META_PAGES; i++) { 2093 if (sb->d[i] == SWAPBLK_NONE) 2094 continue; 2095 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]); 2096 } 2097 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 2098 uma_zfree(swblk_zone, sb); 2099 } 2100 swp_pager_freeswapspace(s_free, n_free); 2101 } 2102 2103 /* 2104 * SWP_PAGER_METACTL() - misc control of swap meta data. 2105 * 2106 * This routine is capable of looking up, or removing swapblk 2107 * assignments in the swap meta data. It returns the swapblk being 2108 * looked-up, popped, or SWAPBLK_NONE if the block was invalid. 2109 * 2110 * When acting on a busy resident page and paging is in progress, we 2111 * have to wait until paging is complete but otherwise can act on the 2112 * busy page. 2113 * 2114 * SWM_POP remove from meta data but do not free it 2115 */ 2116 static daddr_t 2117 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags) 2118 { 2119 struct swblk *sb; 2120 daddr_t r1; 2121 2122 if ((flags & SWM_POP) != 0) 2123 VM_OBJECT_ASSERT_WLOCKED(object); 2124 else 2125 VM_OBJECT_ASSERT_LOCKED(object); 2126 2127 /* 2128 * The meta data only exists if the object is OBJT_SWAP 2129 * and even then might not be allocated yet. 2130 */ 2131 if (object->type != OBJT_SWAP) 2132 return (SWAPBLK_NONE); 2133 2134 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2135 rounddown(pindex, SWAP_META_PAGES)); 2136 if (sb == NULL) 2137 return (SWAPBLK_NONE); 2138 r1 = sb->d[pindex % SWAP_META_PAGES]; 2139 if (r1 == SWAPBLK_NONE) 2140 return (SWAPBLK_NONE); 2141 if ((flags & SWM_POP) != 0) { 2142 sb->d[pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 2143 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 2144 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, 2145 rounddown(pindex, SWAP_META_PAGES)); 2146 uma_zfree(swblk_zone, sb); 2147 } 2148 } 2149 return (r1); 2150 } 2151 2152 /* 2153 * Returns the least page index which is greater than or equal to the 2154 * parameter pindex and for which there is a swap block allocated. 2155 * Returns object's size if the object's type is not swap or if there 2156 * are no allocated swap blocks for the object after the requested 2157 * pindex. 2158 */ 2159 vm_pindex_t 2160 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2161 { 2162 struct swblk *sb; 2163 int i; 2164 2165 VM_OBJECT_ASSERT_LOCKED(object); 2166 if (object->type != OBJT_SWAP) 2167 return (object->size); 2168 2169 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2170 rounddown(pindex, SWAP_META_PAGES)); 2171 if (sb == NULL) 2172 return (object->size); 2173 if (sb->p < pindex) { 2174 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2175 if (sb->d[i] != SWAPBLK_NONE) 2176 return (sb->p + i); 2177 } 2178 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2179 roundup(pindex, SWAP_META_PAGES)); 2180 if (sb == NULL) 2181 return (object->size); 2182 } 2183 for (i = 0; i < SWAP_META_PAGES; i++) { 2184 if (sb->d[i] != SWAPBLK_NONE) 2185 return (sb->p + i); 2186 } 2187 2188 /* 2189 * We get here if a swblk is present in the trie but it 2190 * doesn't map any blocks. 2191 */ 2192 MPASS(0); 2193 return (object->size); 2194 } 2195 2196 /* 2197 * System call swapon(name) enables swapping on device name, 2198 * which must be in the swdevsw. Return EBUSY 2199 * if already swapping on this device. 2200 */ 2201 #ifndef _SYS_SYSPROTO_H_ 2202 struct swapon_args { 2203 char *name; 2204 }; 2205 #endif 2206 2207 /* 2208 * MPSAFE 2209 */ 2210 /* ARGSUSED */ 2211 int 2212 sys_swapon(struct thread *td, struct swapon_args *uap) 2213 { 2214 struct vattr attr; 2215 struct vnode *vp; 2216 struct nameidata nd; 2217 int error; 2218 2219 error = priv_check(td, PRIV_SWAPON); 2220 if (error) 2221 return (error); 2222 2223 sx_xlock(&swdev_syscall_lock); 2224 2225 /* 2226 * Swap metadata may not fit in the KVM if we have physical 2227 * memory of >1GB. 2228 */ 2229 if (swblk_zone == NULL) { 2230 error = ENOMEM; 2231 goto done; 2232 } 2233 2234 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2235 uap->name, td); 2236 error = namei(&nd); 2237 if (error) 2238 goto done; 2239 2240 NDFREE(&nd, NDF_ONLY_PNBUF); 2241 vp = nd.ni_vp; 2242 2243 if (vn_isdisk(vp, &error)) { 2244 error = swapongeom(vp); 2245 } else if (vp->v_type == VREG && 2246 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2247 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2248 /* 2249 * Allow direct swapping to NFS regular files in the same 2250 * way that nfs_mountroot() sets up diskless swapping. 2251 */ 2252 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2253 } 2254 2255 if (error) 2256 vrele(vp); 2257 done: 2258 sx_xunlock(&swdev_syscall_lock); 2259 return (error); 2260 } 2261 2262 /* 2263 * Check that the total amount of swap currently configured does not 2264 * exceed half the theoretical maximum. If it does, print a warning 2265 * message. 2266 */ 2267 static void 2268 swapon_check_swzone(void) 2269 { 2270 2271 /* recommend using no more than half that amount */ 2272 if (swap_total > swap_maxpages / 2) { 2273 printf("warning: total configured swap (%lu pages) " 2274 "exceeds maximum recommended amount (%lu pages).\n", 2275 swap_total, swap_maxpages / 2); 2276 printf("warning: increase kern.maxswzone " 2277 "or reduce amount of swap.\n"); 2278 } 2279 } 2280 2281 static void 2282 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2283 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2284 { 2285 struct swdevt *sp, *tsp; 2286 swblk_t dvbase; 2287 u_long mblocks; 2288 2289 /* 2290 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2291 * First chop nblks off to page-align it, then convert. 2292 * 2293 * sw->sw_nblks is in page-sized chunks now too. 2294 */ 2295 nblks &= ~(ctodb(1) - 1); 2296 nblks = dbtoc(nblks); 2297 2298 /* 2299 * If we go beyond this, we get overflows in the radix 2300 * tree bitmap code. 2301 */ 2302 mblocks = 0x40000000 / BLIST_META_RADIX; 2303 if (nblks > mblocks) { 2304 printf( 2305 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2306 mblocks / 1024 / 1024 * PAGE_SIZE); 2307 nblks = mblocks; 2308 } 2309 2310 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2311 sp->sw_vp = vp; 2312 sp->sw_id = id; 2313 sp->sw_dev = dev; 2314 sp->sw_nblks = nblks; 2315 sp->sw_used = 0; 2316 sp->sw_strategy = strategy; 2317 sp->sw_close = close; 2318 sp->sw_flags = flags; 2319 2320 sp->sw_blist = blist_create(nblks, M_WAITOK); 2321 /* 2322 * Do not free the first blocks in order to avoid overwriting 2323 * any bsd label at the front of the partition 2324 */ 2325 blist_free(sp->sw_blist, howmany(BBSIZE, PAGE_SIZE), 2326 nblks - howmany(BBSIZE, PAGE_SIZE)); 2327 2328 dvbase = 0; 2329 mtx_lock(&sw_dev_mtx); 2330 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2331 if (tsp->sw_end >= dvbase) { 2332 /* 2333 * We put one uncovered page between the devices 2334 * in order to definitively prevent any cross-device 2335 * I/O requests 2336 */ 2337 dvbase = tsp->sw_end + 1; 2338 } 2339 } 2340 sp->sw_first = dvbase; 2341 sp->sw_end = dvbase + nblks; 2342 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2343 nswapdev++; 2344 swap_pager_avail += nblks - howmany(BBSIZE, PAGE_SIZE); 2345 swap_total += nblks; 2346 swapon_check_swzone(); 2347 swp_sizecheck(); 2348 mtx_unlock(&sw_dev_mtx); 2349 EVENTHANDLER_INVOKE(swapon, sp); 2350 } 2351 2352 /* 2353 * SYSCALL: swapoff(devname) 2354 * 2355 * Disable swapping on the given device. 2356 * 2357 * XXX: Badly designed system call: it should use a device index 2358 * rather than filename as specification. We keep sw_vp around 2359 * only to make this work. 2360 */ 2361 #ifndef _SYS_SYSPROTO_H_ 2362 struct swapoff_args { 2363 char *name; 2364 }; 2365 #endif 2366 2367 /* 2368 * MPSAFE 2369 */ 2370 /* ARGSUSED */ 2371 int 2372 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2373 { 2374 struct vnode *vp; 2375 struct nameidata nd; 2376 struct swdevt *sp; 2377 int error; 2378 2379 error = priv_check(td, PRIV_SWAPOFF); 2380 if (error) 2381 return (error); 2382 2383 sx_xlock(&swdev_syscall_lock); 2384 2385 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2386 td); 2387 error = namei(&nd); 2388 if (error) 2389 goto done; 2390 NDFREE(&nd, NDF_ONLY_PNBUF); 2391 vp = nd.ni_vp; 2392 2393 mtx_lock(&sw_dev_mtx); 2394 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2395 if (sp->sw_vp == vp) 2396 break; 2397 } 2398 mtx_unlock(&sw_dev_mtx); 2399 if (sp == NULL) { 2400 error = EINVAL; 2401 goto done; 2402 } 2403 error = swapoff_one(sp, td->td_ucred); 2404 done: 2405 sx_xunlock(&swdev_syscall_lock); 2406 return (error); 2407 } 2408 2409 static int 2410 swapoff_one(struct swdevt *sp, struct ucred *cred) 2411 { 2412 u_long nblks; 2413 #ifdef MAC 2414 int error; 2415 #endif 2416 2417 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2418 #ifdef MAC 2419 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2420 error = mac_system_check_swapoff(cred, sp->sw_vp); 2421 (void) VOP_UNLOCK(sp->sw_vp, 0); 2422 if (error != 0) 2423 return (error); 2424 #endif 2425 nblks = sp->sw_nblks; 2426 2427 /* 2428 * We can turn off this swap device safely only if the 2429 * available virtual memory in the system will fit the amount 2430 * of data we will have to page back in, plus an epsilon so 2431 * the system doesn't become critically low on swap space. 2432 */ 2433 if (vm_free_count() + swap_pager_avail < nblks + nswap_lowat) 2434 return (ENOMEM); 2435 2436 /* 2437 * Prevent further allocations on this device. 2438 */ 2439 mtx_lock(&sw_dev_mtx); 2440 sp->sw_flags |= SW_CLOSING; 2441 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2442 swap_total -= nblks; 2443 mtx_unlock(&sw_dev_mtx); 2444 2445 /* 2446 * Page in the contents of the device and close it. 2447 */ 2448 swap_pager_swapoff(sp); 2449 2450 sp->sw_close(curthread, sp); 2451 mtx_lock(&sw_dev_mtx); 2452 sp->sw_id = NULL; 2453 TAILQ_REMOVE(&swtailq, sp, sw_list); 2454 nswapdev--; 2455 if (nswapdev == 0) { 2456 swap_pager_full = 2; 2457 swap_pager_almost_full = 1; 2458 } 2459 if (swdevhd == sp) 2460 swdevhd = NULL; 2461 mtx_unlock(&sw_dev_mtx); 2462 blist_destroy(sp->sw_blist); 2463 free(sp, M_VMPGDATA); 2464 return (0); 2465 } 2466 2467 void 2468 swapoff_all(void) 2469 { 2470 struct swdevt *sp, *spt; 2471 const char *devname; 2472 int error; 2473 2474 sx_xlock(&swdev_syscall_lock); 2475 2476 mtx_lock(&sw_dev_mtx); 2477 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2478 mtx_unlock(&sw_dev_mtx); 2479 if (vn_isdisk(sp->sw_vp, NULL)) 2480 devname = devtoname(sp->sw_vp->v_rdev); 2481 else 2482 devname = "[file]"; 2483 error = swapoff_one(sp, thread0.td_ucred); 2484 if (error != 0) { 2485 printf("Cannot remove swap device %s (error=%d), " 2486 "skipping.\n", devname, error); 2487 } else if (bootverbose) { 2488 printf("Swap device %s removed.\n", devname); 2489 } 2490 mtx_lock(&sw_dev_mtx); 2491 } 2492 mtx_unlock(&sw_dev_mtx); 2493 2494 sx_xunlock(&swdev_syscall_lock); 2495 } 2496 2497 void 2498 swap_pager_status(int *total, int *used) 2499 { 2500 struct swdevt *sp; 2501 2502 *total = 0; 2503 *used = 0; 2504 mtx_lock(&sw_dev_mtx); 2505 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2506 *total += sp->sw_nblks; 2507 *used += sp->sw_used; 2508 } 2509 mtx_unlock(&sw_dev_mtx); 2510 } 2511 2512 int 2513 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2514 { 2515 struct swdevt *sp; 2516 const char *tmp_devname; 2517 int error, n; 2518 2519 n = 0; 2520 error = ENOENT; 2521 mtx_lock(&sw_dev_mtx); 2522 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2523 if (n != name) { 2524 n++; 2525 continue; 2526 } 2527 xs->xsw_version = XSWDEV_VERSION; 2528 xs->xsw_dev = sp->sw_dev; 2529 xs->xsw_flags = sp->sw_flags; 2530 xs->xsw_nblks = sp->sw_nblks; 2531 xs->xsw_used = sp->sw_used; 2532 if (devname != NULL) { 2533 if (vn_isdisk(sp->sw_vp, NULL)) 2534 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2535 else 2536 tmp_devname = "[file]"; 2537 strncpy(devname, tmp_devname, len); 2538 } 2539 error = 0; 2540 break; 2541 } 2542 mtx_unlock(&sw_dev_mtx); 2543 return (error); 2544 } 2545 2546 #if defined(COMPAT_FREEBSD11) 2547 #define XSWDEV_VERSION_11 1 2548 struct xswdev11 { 2549 u_int xsw_version; 2550 uint32_t xsw_dev; 2551 int xsw_flags; 2552 int xsw_nblks; 2553 int xsw_used; 2554 }; 2555 #endif 2556 2557 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2558 struct xswdev32 { 2559 u_int xsw_version; 2560 u_int xsw_dev1, xsw_dev2; 2561 int xsw_flags; 2562 int xsw_nblks; 2563 int xsw_used; 2564 }; 2565 #endif 2566 2567 static int 2568 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2569 { 2570 struct xswdev xs; 2571 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2572 struct xswdev32 xs32; 2573 #endif 2574 #if defined(COMPAT_FREEBSD11) 2575 struct xswdev11 xs11; 2576 #endif 2577 int error; 2578 2579 if (arg2 != 1) /* name length */ 2580 return (EINVAL); 2581 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2582 if (error != 0) 2583 return (error); 2584 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2585 if (req->oldlen == sizeof(xs32)) { 2586 xs32.xsw_version = XSWDEV_VERSION; 2587 xs32.xsw_dev1 = xs.xsw_dev; 2588 xs32.xsw_dev2 = xs.xsw_dev >> 32; 2589 xs32.xsw_flags = xs.xsw_flags; 2590 xs32.xsw_nblks = xs.xsw_nblks; 2591 xs32.xsw_used = xs.xsw_used; 2592 error = SYSCTL_OUT(req, &xs32, sizeof(xs32)); 2593 return (error); 2594 } 2595 #endif 2596 #if defined(COMPAT_FREEBSD11) 2597 if (req->oldlen == sizeof(xs11)) { 2598 xs11.xsw_version = XSWDEV_VERSION_11; 2599 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2600 xs11.xsw_flags = xs.xsw_flags; 2601 xs11.xsw_nblks = xs.xsw_nblks; 2602 xs11.xsw_used = xs.xsw_used; 2603 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2604 return (error); 2605 } 2606 #endif 2607 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2608 return (error); 2609 } 2610 2611 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2612 "Number of swap devices"); 2613 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2614 sysctl_vm_swap_info, 2615 "Swap statistics by device"); 2616 2617 /* 2618 * Count the approximate swap usage in pages for a vmspace. The 2619 * shadowed or not yet copied on write swap blocks are not accounted. 2620 * The map must be locked. 2621 */ 2622 long 2623 vmspace_swap_count(struct vmspace *vmspace) 2624 { 2625 vm_map_t map; 2626 vm_map_entry_t cur; 2627 vm_object_t object; 2628 struct swblk *sb; 2629 vm_pindex_t e, pi; 2630 long count; 2631 int i; 2632 2633 map = &vmspace->vm_map; 2634 count = 0; 2635 2636 VM_MAP_ENTRY_FOREACH(cur, map) { 2637 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 2638 continue; 2639 object = cur->object.vm_object; 2640 if (object == NULL || object->type != OBJT_SWAP) 2641 continue; 2642 VM_OBJECT_RLOCK(object); 2643 if (object->type != OBJT_SWAP) 2644 goto unlock; 2645 pi = OFF_TO_IDX(cur->offset); 2646 e = pi + OFF_TO_IDX(cur->end - cur->start); 2647 for (;; pi = sb->p + SWAP_META_PAGES) { 2648 sb = SWAP_PCTRIE_LOOKUP_GE( 2649 &object->un_pager.swp.swp_blks, pi); 2650 if (sb == NULL || sb->p >= e) 2651 break; 2652 for (i = 0; i < SWAP_META_PAGES; i++) { 2653 if (sb->p + i < e && 2654 sb->d[i] != SWAPBLK_NONE) 2655 count++; 2656 } 2657 } 2658 unlock: 2659 VM_OBJECT_RUNLOCK(object); 2660 } 2661 return (count); 2662 } 2663 2664 /* 2665 * GEOM backend 2666 * 2667 * Swapping onto disk devices. 2668 * 2669 */ 2670 2671 static g_orphan_t swapgeom_orphan; 2672 2673 static struct g_class g_swap_class = { 2674 .name = "SWAP", 2675 .version = G_VERSION, 2676 .orphan = swapgeom_orphan, 2677 }; 2678 2679 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2680 2681 2682 static void 2683 swapgeom_close_ev(void *arg, int flags) 2684 { 2685 struct g_consumer *cp; 2686 2687 cp = arg; 2688 g_access(cp, -1, -1, 0); 2689 g_detach(cp); 2690 g_destroy_consumer(cp); 2691 } 2692 2693 /* 2694 * Add a reference to the g_consumer for an inflight transaction. 2695 */ 2696 static void 2697 swapgeom_acquire(struct g_consumer *cp) 2698 { 2699 2700 mtx_assert(&sw_dev_mtx, MA_OWNED); 2701 cp->index++; 2702 } 2703 2704 /* 2705 * Remove a reference from the g_consumer. Post a close event if all 2706 * references go away, since the function might be called from the 2707 * biodone context. 2708 */ 2709 static void 2710 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2711 { 2712 2713 mtx_assert(&sw_dev_mtx, MA_OWNED); 2714 cp->index--; 2715 if (cp->index == 0) { 2716 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2717 sp->sw_id = NULL; 2718 } 2719 } 2720 2721 static void 2722 swapgeom_done(struct bio *bp2) 2723 { 2724 struct swdevt *sp; 2725 struct buf *bp; 2726 struct g_consumer *cp; 2727 2728 bp = bp2->bio_caller2; 2729 cp = bp2->bio_from; 2730 bp->b_ioflags = bp2->bio_flags; 2731 if (bp2->bio_error) 2732 bp->b_ioflags |= BIO_ERROR; 2733 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2734 bp->b_error = bp2->bio_error; 2735 bp->b_caller1 = NULL; 2736 bufdone(bp); 2737 sp = bp2->bio_caller1; 2738 mtx_lock(&sw_dev_mtx); 2739 swapgeom_release(cp, sp); 2740 mtx_unlock(&sw_dev_mtx); 2741 g_destroy_bio(bp2); 2742 } 2743 2744 static void 2745 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2746 { 2747 struct bio *bio; 2748 struct g_consumer *cp; 2749 2750 mtx_lock(&sw_dev_mtx); 2751 cp = sp->sw_id; 2752 if (cp == NULL) { 2753 mtx_unlock(&sw_dev_mtx); 2754 bp->b_error = ENXIO; 2755 bp->b_ioflags |= BIO_ERROR; 2756 bufdone(bp); 2757 return; 2758 } 2759 swapgeom_acquire(cp); 2760 mtx_unlock(&sw_dev_mtx); 2761 if (bp->b_iocmd == BIO_WRITE) 2762 bio = g_new_bio(); 2763 else 2764 bio = g_alloc_bio(); 2765 if (bio == NULL) { 2766 mtx_lock(&sw_dev_mtx); 2767 swapgeom_release(cp, sp); 2768 mtx_unlock(&sw_dev_mtx); 2769 bp->b_error = ENOMEM; 2770 bp->b_ioflags |= BIO_ERROR; 2771 printf("swap_pager: cannot allocate bio\n"); 2772 bufdone(bp); 2773 return; 2774 } 2775 2776 bp->b_caller1 = bio; 2777 bio->bio_caller1 = sp; 2778 bio->bio_caller2 = bp; 2779 bio->bio_cmd = bp->b_iocmd; 2780 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2781 bio->bio_length = bp->b_bcount; 2782 bio->bio_done = swapgeom_done; 2783 if (!buf_mapped(bp)) { 2784 bio->bio_ma = bp->b_pages; 2785 bio->bio_data = unmapped_buf; 2786 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2787 bio->bio_ma_n = bp->b_npages; 2788 bio->bio_flags |= BIO_UNMAPPED; 2789 } else { 2790 bio->bio_data = bp->b_data; 2791 bio->bio_ma = NULL; 2792 } 2793 g_io_request(bio, cp); 2794 return; 2795 } 2796 2797 static void 2798 swapgeom_orphan(struct g_consumer *cp) 2799 { 2800 struct swdevt *sp; 2801 int destroy; 2802 2803 mtx_lock(&sw_dev_mtx); 2804 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2805 if (sp->sw_id == cp) { 2806 sp->sw_flags |= SW_CLOSING; 2807 break; 2808 } 2809 } 2810 /* 2811 * Drop reference we were created with. Do directly since we're in a 2812 * special context where we don't have to queue the call to 2813 * swapgeom_close_ev(). 2814 */ 2815 cp->index--; 2816 destroy = ((sp != NULL) && (cp->index == 0)); 2817 if (destroy) 2818 sp->sw_id = NULL; 2819 mtx_unlock(&sw_dev_mtx); 2820 if (destroy) 2821 swapgeom_close_ev(cp, 0); 2822 } 2823 2824 static void 2825 swapgeom_close(struct thread *td, struct swdevt *sw) 2826 { 2827 struct g_consumer *cp; 2828 2829 mtx_lock(&sw_dev_mtx); 2830 cp = sw->sw_id; 2831 sw->sw_id = NULL; 2832 mtx_unlock(&sw_dev_mtx); 2833 2834 /* 2835 * swapgeom_close() may be called from the biodone context, 2836 * where we cannot perform topology changes. Delegate the 2837 * work to the events thread. 2838 */ 2839 if (cp != NULL) 2840 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2841 } 2842 2843 static int 2844 swapongeom_locked(struct cdev *dev, struct vnode *vp) 2845 { 2846 struct g_provider *pp; 2847 struct g_consumer *cp; 2848 static struct g_geom *gp; 2849 struct swdevt *sp; 2850 u_long nblks; 2851 int error; 2852 2853 pp = g_dev_getprovider(dev); 2854 if (pp == NULL) 2855 return (ENODEV); 2856 mtx_lock(&sw_dev_mtx); 2857 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2858 cp = sp->sw_id; 2859 if (cp != NULL && cp->provider == pp) { 2860 mtx_unlock(&sw_dev_mtx); 2861 return (EBUSY); 2862 } 2863 } 2864 mtx_unlock(&sw_dev_mtx); 2865 if (gp == NULL) 2866 gp = g_new_geomf(&g_swap_class, "swap"); 2867 cp = g_new_consumer(gp); 2868 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2869 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2870 g_attach(cp, pp); 2871 /* 2872 * XXX: Every time you think you can improve the margin for 2873 * footshooting, somebody depends on the ability to do so: 2874 * savecore(8) wants to write to our swapdev so we cannot 2875 * set an exclusive count :-( 2876 */ 2877 error = g_access(cp, 1, 1, 0); 2878 if (error != 0) { 2879 g_detach(cp); 2880 g_destroy_consumer(cp); 2881 return (error); 2882 } 2883 nblks = pp->mediasize / DEV_BSIZE; 2884 swaponsomething(vp, cp, nblks, swapgeom_strategy, 2885 swapgeom_close, dev2udev(dev), 2886 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2887 return (0); 2888 } 2889 2890 static int 2891 swapongeom(struct vnode *vp) 2892 { 2893 int error; 2894 2895 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2896 if (vp->v_type != VCHR || (vp->v_iflag & VI_DOOMED) != 0) { 2897 error = ENOENT; 2898 } else { 2899 g_topology_lock(); 2900 error = swapongeom_locked(vp->v_rdev, vp); 2901 g_topology_unlock(); 2902 } 2903 VOP_UNLOCK(vp, 0); 2904 return (error); 2905 } 2906 2907 /* 2908 * VNODE backend 2909 * 2910 * This is used mainly for network filesystem (read: probably only tested 2911 * with NFS) swapfiles. 2912 * 2913 */ 2914 2915 static void 2916 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2917 { 2918 struct vnode *vp2; 2919 2920 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2921 2922 vp2 = sp->sw_id; 2923 vhold(vp2); 2924 if (bp->b_iocmd == BIO_WRITE) { 2925 if (bp->b_bufobj) 2926 bufobj_wdrop(bp->b_bufobj); 2927 bufobj_wref(&vp2->v_bufobj); 2928 } 2929 if (bp->b_bufobj != &vp2->v_bufobj) 2930 bp->b_bufobj = &vp2->v_bufobj; 2931 bp->b_vp = vp2; 2932 bp->b_iooffset = dbtob(bp->b_blkno); 2933 bstrategy(bp); 2934 return; 2935 } 2936 2937 static void 2938 swapdev_close(struct thread *td, struct swdevt *sp) 2939 { 2940 2941 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2942 vrele(sp->sw_vp); 2943 } 2944 2945 2946 static int 2947 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2948 { 2949 struct swdevt *sp; 2950 int error; 2951 2952 if (nblks == 0) 2953 return (ENXIO); 2954 mtx_lock(&sw_dev_mtx); 2955 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2956 if (sp->sw_id == vp) { 2957 mtx_unlock(&sw_dev_mtx); 2958 return (EBUSY); 2959 } 2960 } 2961 mtx_unlock(&sw_dev_mtx); 2962 2963 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2964 #ifdef MAC 2965 error = mac_system_check_swapon(td->td_ucred, vp); 2966 if (error == 0) 2967 #endif 2968 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 2969 (void) VOP_UNLOCK(vp, 0); 2970 if (error) 2971 return (error); 2972 2973 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 2974 NODEV, 0); 2975 return (0); 2976 } 2977 2978 static int 2979 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 2980 { 2981 int error, new, n; 2982 2983 new = nsw_wcount_async_max; 2984 error = sysctl_handle_int(oidp, &new, 0, req); 2985 if (error != 0 || req->newptr == NULL) 2986 return (error); 2987 2988 if (new > nswbuf / 2 || new < 1) 2989 return (EINVAL); 2990 2991 mtx_lock(&swbuf_mtx); 2992 while (nsw_wcount_async_max != new) { 2993 /* 2994 * Adjust difference. If the current async count is too low, 2995 * we will need to sqeeze our update slowly in. Sleep with a 2996 * higher priority than getpbuf() to finish faster. 2997 */ 2998 n = new - nsw_wcount_async_max; 2999 if (nsw_wcount_async + n >= 0) { 3000 nsw_wcount_async += n; 3001 nsw_wcount_async_max += n; 3002 wakeup(&nsw_wcount_async); 3003 } else { 3004 nsw_wcount_async_max -= nsw_wcount_async; 3005 nsw_wcount_async = 0; 3006 msleep(&nsw_wcount_async, &swbuf_mtx, PSWP, 3007 "swpsysctl", 0); 3008 } 3009 } 3010 mtx_unlock(&swbuf_mtx); 3011 3012 return (0); 3013 } 3014 3015 static void 3016 swap_pager_update_writecount(vm_object_t object, vm_offset_t start, 3017 vm_offset_t end) 3018 { 3019 3020 VM_OBJECT_WLOCK(object); 3021 KASSERT((object->flags & OBJ_NOSPLIT) != 0, 3022 ("Splittable object with writecount")); 3023 object->un_pager.swp.writemappings += (vm_ooffset_t)end - start; 3024 VM_OBJECT_WUNLOCK(object); 3025 } 3026 3027 static void 3028 swap_pager_release_writecount(vm_object_t object, vm_offset_t start, 3029 vm_offset_t end) 3030 { 3031 3032 VM_OBJECT_WLOCK(object); 3033 KASSERT((object->flags & OBJ_NOSPLIT) != 0, 3034 ("Splittable object with writecount")); 3035 object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start; 3036 VM_OBJECT_WUNLOCK(object); 3037 } 3038