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