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); 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 the requested number of pages. The starting 712 * swap block number (a page index) is returned or SWAPBLK_NONE 713 * if the allocation failed. 714 * 715 * Also has the side effect of advising that somebody made a mistake 716 * when they configured swap and didn't configure enough. 717 * 718 * This routine may not sleep. 719 * 720 * We allocate in round-robin fashion from the configured devices. 721 */ 722 static daddr_t 723 swp_pager_getswapspace(int npages) 724 { 725 daddr_t blk; 726 struct swdevt *sp; 727 int i; 728 729 blk = SWAPBLK_NONE; 730 mtx_lock(&sw_dev_mtx); 731 sp = swdevhd; 732 for (i = 0; i < nswapdev; i++) { 733 if (sp == NULL) 734 sp = TAILQ_FIRST(&swtailq); 735 if (!(sp->sw_flags & SW_CLOSING)) { 736 blk = blist_alloc(sp->sw_blist, npages); 737 if (blk != SWAPBLK_NONE) { 738 blk += sp->sw_first; 739 sp->sw_used += npages; 740 swap_pager_avail -= npages; 741 swp_sizecheck(); 742 swdevhd = TAILQ_NEXT(sp, sw_list); 743 goto done; 744 } 745 } 746 sp = TAILQ_NEXT(sp, sw_list); 747 } 748 if (swap_pager_full != 2) { 749 printf("swap_pager_getswapspace(%d): failed\n", npages); 750 swap_pager_full = 2; 751 swap_pager_almost_full = 1; 752 } 753 swdevhd = NULL; 754 done: 755 mtx_unlock(&sw_dev_mtx); 756 return (blk); 757 } 758 759 static bool 760 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 761 { 762 763 return (blk >= sp->sw_first && blk < sp->sw_end); 764 } 765 766 static void 767 swp_pager_strategy(struct buf *bp) 768 { 769 struct swdevt *sp; 770 771 mtx_lock(&sw_dev_mtx); 772 TAILQ_FOREACH(sp, &swtailq, sw_list) { 773 if (swp_pager_isondev(bp->b_blkno, sp)) { 774 mtx_unlock(&sw_dev_mtx); 775 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 776 unmapped_buf_allowed) { 777 bp->b_data = unmapped_buf; 778 bp->b_offset = 0; 779 } else { 780 pmap_qenter((vm_offset_t)bp->b_data, 781 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 782 } 783 sp->sw_strategy(bp, sp); 784 return; 785 } 786 } 787 panic("Swapdev not found"); 788 } 789 790 791 /* 792 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 793 * 794 * This routine returns the specified swap blocks back to the bitmap. 795 * 796 * This routine may not sleep. 797 */ 798 static void 799 swp_pager_freeswapspace(daddr_t blk, daddr_t npages) 800 { 801 struct swdevt *sp; 802 803 if (npages == 0) 804 return; 805 mtx_lock(&sw_dev_mtx); 806 TAILQ_FOREACH(sp, &swtailq, sw_list) { 807 if (swp_pager_isondev(blk, sp)) { 808 sp->sw_used -= npages; 809 /* 810 * If we are attempting to stop swapping on 811 * this device, we don't want to mark any 812 * blocks free lest they be reused. 813 */ 814 if ((sp->sw_flags & SW_CLOSING) == 0) { 815 blist_free(sp->sw_blist, blk - sp->sw_first, 816 npages); 817 swap_pager_avail += npages; 818 swp_sizecheck(); 819 } 820 mtx_unlock(&sw_dev_mtx); 821 return; 822 } 823 } 824 panic("Swapdev not found"); 825 } 826 827 /* 828 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 829 */ 830 static int 831 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 832 { 833 struct sbuf sbuf; 834 struct swdevt *sp; 835 const char *devname; 836 int error; 837 838 error = sysctl_wire_old_buffer(req, 0); 839 if (error != 0) 840 return (error); 841 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 842 mtx_lock(&sw_dev_mtx); 843 TAILQ_FOREACH(sp, &swtailq, sw_list) { 844 if (vn_isdisk(sp->sw_vp, NULL)) 845 devname = devtoname(sp->sw_vp->v_rdev); 846 else 847 devname = "[file]"; 848 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 849 blist_stats(sp->sw_blist, &sbuf); 850 } 851 mtx_unlock(&sw_dev_mtx); 852 error = sbuf_finish(&sbuf); 853 sbuf_delete(&sbuf); 854 return (error); 855 } 856 857 /* 858 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 859 * range within an object. 860 * 861 * This is a globally accessible routine. 862 * 863 * This routine removes swapblk assignments from swap metadata. 864 * 865 * The external callers of this routine typically have already destroyed 866 * or renamed vm_page_t's associated with this range in the object so 867 * we should be ok. 868 * 869 * The object must be locked. 870 */ 871 void 872 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 873 { 874 875 swp_pager_meta_free(object, start, size); 876 } 877 878 /* 879 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 880 * 881 * Assigns swap blocks to the specified range within the object. The 882 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 883 * 884 * Returns 0 on success, -1 on failure. 885 */ 886 int 887 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 888 { 889 int n = 0; 890 daddr_t blk = SWAPBLK_NONE; 891 vm_pindex_t beg = start; /* save start index */ 892 daddr_t addr, n_free, s_free; 893 894 swp_pager_init_freerange(&s_free, &n_free); 895 VM_OBJECT_WLOCK(object); 896 while (size) { 897 if (n == 0) { 898 n = BLIST_MAX_ALLOC; 899 while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) { 900 n >>= 1; 901 if (n == 0) { 902 swp_pager_meta_free(object, beg, start - beg); 903 VM_OBJECT_WUNLOCK(object); 904 return (-1); 905 } 906 } 907 } 908 addr = swp_pager_meta_build(object, start, blk); 909 if (addr != SWAPBLK_NONE) 910 swp_pager_update_freerange(&s_free, &n_free, addr); 911 --size; 912 ++start; 913 ++blk; 914 --n; 915 } 916 swp_pager_freeswapspace(s_free, n_free); 917 swp_pager_meta_free(object, start, n); 918 VM_OBJECT_WUNLOCK(object); 919 return (0); 920 } 921 922 /* 923 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 924 * and destroy the source. 925 * 926 * Copy any valid swapblks from the source to the destination. In 927 * cases where both the source and destination have a valid swapblk, 928 * we keep the destination's. 929 * 930 * This routine is allowed to sleep. It may sleep allocating metadata 931 * indirectly through swp_pager_meta_build() or if paging is still in 932 * progress on the source. 933 * 934 * The source object contains no vm_page_t's (which is just as well) 935 * 936 * The source object is of type OBJT_SWAP. 937 * 938 * The source and destination objects must be locked. 939 * Both object locks may temporarily be released. 940 */ 941 void 942 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 943 vm_pindex_t offset, int destroysource) 944 { 945 vm_pindex_t i; 946 daddr_t dstaddr, n_free, s_free, srcaddr; 947 948 VM_OBJECT_ASSERT_WLOCKED(srcobject); 949 VM_OBJECT_ASSERT_WLOCKED(dstobject); 950 951 /* 952 * If destroysource is set, we remove the source object from the 953 * swap_pager internal queue now. 954 */ 955 if (destroysource && srcobject->handle != NULL) { 956 vm_object_pip_add(srcobject, 1); 957 VM_OBJECT_WUNLOCK(srcobject); 958 vm_object_pip_add(dstobject, 1); 959 VM_OBJECT_WUNLOCK(dstobject); 960 sx_xlock(&sw_alloc_sx); 961 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 962 pager_object_list); 963 sx_xunlock(&sw_alloc_sx); 964 VM_OBJECT_WLOCK(dstobject); 965 vm_object_pip_wakeup(dstobject); 966 VM_OBJECT_WLOCK(srcobject); 967 vm_object_pip_wakeup(srcobject); 968 } 969 970 /* 971 * Transfer source to destination. 972 */ 973 swp_pager_init_freerange(&s_free, &n_free); 974 for (i = 0; i < dstobject->size; ++i) { 975 srcaddr = swp_pager_meta_ctl(srcobject, i + offset, SWM_POP); 976 if (srcaddr == SWAPBLK_NONE) 977 continue; 978 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 979 if (dstaddr != SWAPBLK_NONE) { 980 /* 981 * Destination has valid swapblk or it is represented 982 * by a resident page. We destroy the source block. 983 */ 984 swp_pager_update_freerange(&s_free, &n_free, srcaddr); 985 continue; 986 } 987 988 /* 989 * Destination has no swapblk and is not resident, 990 * copy source. 991 * 992 * swp_pager_meta_build() can sleep. 993 */ 994 vm_object_pip_add(srcobject, 1); 995 VM_OBJECT_WUNLOCK(srcobject); 996 vm_object_pip_add(dstobject, 1); 997 dstaddr = swp_pager_meta_build(dstobject, i, srcaddr); 998 KASSERT(dstaddr == SWAPBLK_NONE, 999 ("Unexpected destination swapblk")); 1000 vm_object_pip_wakeup(dstobject); 1001 VM_OBJECT_WLOCK(srcobject); 1002 vm_object_pip_wakeup(srcobject); 1003 } 1004 swp_pager_freeswapspace(s_free, n_free); 1005 1006 /* 1007 * Free left over swap blocks in source. 1008 * 1009 * We have to revert the type to OBJT_DEFAULT so we do not accidentally 1010 * double-remove the object from the swap queues. 1011 */ 1012 if (destroysource) { 1013 swp_pager_meta_free_all(srcobject); 1014 /* 1015 * Reverting the type is not necessary, the caller is going 1016 * to destroy srcobject directly, but I'm doing it here 1017 * for consistency since we've removed the object from its 1018 * queues. 1019 */ 1020 srcobject->type = OBJT_DEFAULT; 1021 } 1022 } 1023 1024 /* 1025 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1026 * the requested page. 1027 * 1028 * We determine whether good backing store exists for the requested 1029 * page and return TRUE if it does, FALSE if it doesn't. 1030 * 1031 * If TRUE, we also try to determine how much valid, contiguous backing 1032 * store exists before and after the requested page. 1033 */ 1034 static boolean_t 1035 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1036 int *after) 1037 { 1038 daddr_t blk, blk0; 1039 int i; 1040 1041 VM_OBJECT_ASSERT_LOCKED(object); 1042 1043 /* 1044 * do we have good backing store at the requested index ? 1045 */ 1046 blk0 = swp_pager_meta_ctl(object, pindex, 0); 1047 if (blk0 == SWAPBLK_NONE) { 1048 if (before) 1049 *before = 0; 1050 if (after) 1051 *after = 0; 1052 return (FALSE); 1053 } 1054 1055 /* 1056 * find backwards-looking contiguous good backing store 1057 */ 1058 if (before != NULL) { 1059 for (i = 1; i < SWB_NPAGES; i++) { 1060 if (i > pindex) 1061 break; 1062 blk = swp_pager_meta_ctl(object, pindex - i, 0); 1063 if (blk != blk0 - i) 1064 break; 1065 } 1066 *before = i - 1; 1067 } 1068 1069 /* 1070 * find forward-looking contiguous good backing store 1071 */ 1072 if (after != NULL) { 1073 for (i = 1; i < SWB_NPAGES; i++) { 1074 blk = swp_pager_meta_ctl(object, pindex + i, 0); 1075 if (blk != blk0 + i) 1076 break; 1077 } 1078 *after = i - 1; 1079 } 1080 return (TRUE); 1081 } 1082 1083 /* 1084 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1085 * 1086 * This removes any associated swap backing store, whether valid or 1087 * not, from the page. 1088 * 1089 * This routine is typically called when a page is made dirty, at 1090 * which point any associated swap can be freed. MADV_FREE also 1091 * calls us in a special-case situation 1092 * 1093 * NOTE!!! If the page is clean and the swap was valid, the caller 1094 * should make the page dirty before calling this routine. This routine 1095 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1096 * depends on it. 1097 * 1098 * This routine may not sleep. 1099 * 1100 * The object containing the page must be locked. 1101 */ 1102 static void 1103 swap_pager_unswapped(vm_page_t m) 1104 { 1105 daddr_t srcaddr; 1106 1107 srcaddr = swp_pager_meta_ctl(m->object, m->pindex, SWM_POP); 1108 if (srcaddr != SWAPBLK_NONE) 1109 swp_pager_freeswapspace(srcaddr, 1); 1110 } 1111 1112 /* 1113 * swap_pager_getpages() - bring pages in from swap 1114 * 1115 * Attempt to page in the pages in array "ma" of length "count". The 1116 * caller may optionally specify that additional pages preceding and 1117 * succeeding the specified range be paged in. The number of such pages 1118 * is returned in the "rbehind" and "rahead" parameters, and they will 1119 * be in the inactive queue upon return. 1120 * 1121 * The pages in "ma" must be busied and will remain busied upon return. 1122 */ 1123 static int 1124 swap_pager_getpages(vm_object_t object, vm_page_t *ma, int count, int *rbehind, 1125 int *rahead) 1126 { 1127 struct buf *bp; 1128 vm_page_t bm, mpred, msucc, p; 1129 vm_pindex_t pindex; 1130 daddr_t blk; 1131 int i, maxahead, maxbehind, reqcount; 1132 1133 reqcount = count; 1134 1135 /* 1136 * Determine the final number of read-behind pages and 1137 * allocate them BEFORE releasing the object lock. Otherwise, 1138 * there can be a problematic race with vm_object_split(). 1139 * Specifically, vm_object_split() might first transfer pages 1140 * that precede ma[0] in the current object to a new object, 1141 * and then this function incorrectly recreates those pages as 1142 * read-behind pages in the current object. 1143 */ 1144 if (!swap_pager_haspage(object, ma[0]->pindex, &maxbehind, &maxahead)) 1145 return (VM_PAGER_FAIL); 1146 1147 /* 1148 * Clip the readahead and readbehind ranges to exclude resident pages. 1149 */ 1150 if (rahead != NULL) { 1151 KASSERT(reqcount - 1 <= maxahead, 1152 ("page count %d extends beyond swap block", reqcount)); 1153 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1154 pindex = ma[reqcount - 1]->pindex; 1155 msucc = TAILQ_NEXT(ma[reqcount - 1], listq); 1156 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1157 *rahead = msucc->pindex - pindex - 1; 1158 } 1159 if (rbehind != NULL) { 1160 *rbehind = imin(*rbehind, maxbehind); 1161 pindex = ma[0]->pindex; 1162 mpred = TAILQ_PREV(ma[0], pglist, listq); 1163 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1164 *rbehind = pindex - mpred->pindex - 1; 1165 } 1166 1167 bm = ma[0]; 1168 for (i = 0; i < count; i++) 1169 ma[i]->oflags |= VPO_SWAPINPROG; 1170 1171 /* 1172 * Allocate readahead and readbehind pages. 1173 */ 1174 if (rbehind != NULL) { 1175 for (i = 1; i <= *rbehind; i++) { 1176 p = vm_page_alloc(object, ma[0]->pindex - i, 1177 VM_ALLOC_NORMAL); 1178 if (p == NULL) 1179 break; 1180 p->oflags |= VPO_SWAPINPROG; 1181 bm = p; 1182 } 1183 *rbehind = i - 1; 1184 } 1185 if (rahead != NULL) { 1186 for (i = 0; i < *rahead; i++) { 1187 p = vm_page_alloc(object, 1188 ma[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1189 if (p == NULL) 1190 break; 1191 p->oflags |= VPO_SWAPINPROG; 1192 } 1193 *rahead = i; 1194 } 1195 if (rbehind != NULL) 1196 count += *rbehind; 1197 if (rahead != NULL) 1198 count += *rahead; 1199 1200 vm_object_pip_add(object, count); 1201 1202 pindex = bm->pindex; 1203 blk = swp_pager_meta_ctl(object, pindex, 0); 1204 KASSERT(blk != SWAPBLK_NONE, 1205 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1206 1207 VM_OBJECT_WUNLOCK(object); 1208 bp = uma_zalloc(swrbuf_zone, M_WAITOK); 1209 /* Pages cannot leave the object while busy. */ 1210 for (i = 0, p = bm; i < count; i++, p = TAILQ_NEXT(p, listq)) { 1211 MPASS(p->pindex == bm->pindex + i); 1212 bp->b_pages[i] = p; 1213 } 1214 1215 bp->b_flags |= B_PAGING; 1216 bp->b_iocmd = BIO_READ; 1217 bp->b_iodone = swp_pager_async_iodone; 1218 bp->b_rcred = crhold(thread0.td_ucred); 1219 bp->b_wcred = crhold(thread0.td_ucred); 1220 bp->b_blkno = blk; 1221 bp->b_bcount = PAGE_SIZE * count; 1222 bp->b_bufsize = PAGE_SIZE * count; 1223 bp->b_npages = count; 1224 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1225 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1226 1227 VM_CNT_INC(v_swapin); 1228 VM_CNT_ADD(v_swappgsin, count); 1229 1230 /* 1231 * perform the I/O. NOTE!!! bp cannot be considered valid after 1232 * this point because we automatically release it on completion. 1233 * Instead, we look at the one page we are interested in which we 1234 * still hold a lock on even through the I/O completion. 1235 * 1236 * The other pages in our ma[] array are also released on completion, 1237 * so we cannot assume they are valid anymore either. 1238 * 1239 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1240 */ 1241 BUF_KERNPROC(bp); 1242 swp_pager_strategy(bp); 1243 1244 /* 1245 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1246 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1247 * is set in the metadata for each page in the request. 1248 */ 1249 VM_OBJECT_WLOCK(object); 1250 while ((ma[0]->oflags & VPO_SWAPINPROG) != 0) { 1251 ma[0]->oflags |= VPO_SWAPSLEEP; 1252 VM_CNT_INC(v_intrans); 1253 if (VM_OBJECT_SLEEP(object, &object->paging_in_progress, PSWP, 1254 "swread", hz * 20)) { 1255 printf( 1256 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1257 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1258 } 1259 } 1260 1261 /* 1262 * If we had an unrecoverable read error pages will not be valid. 1263 */ 1264 for (i = 0; i < reqcount; i++) 1265 if (ma[i]->valid != VM_PAGE_BITS_ALL) 1266 return (VM_PAGER_ERROR); 1267 1268 return (VM_PAGER_OK); 1269 1270 /* 1271 * A final note: in a low swap situation, we cannot deallocate swap 1272 * and mark a page dirty here because the caller is likely to mark 1273 * the page clean when we return, causing the page to possibly revert 1274 * to all-zero's later. 1275 */ 1276 } 1277 1278 /* 1279 * swap_pager_getpages_async(): 1280 * 1281 * Right now this is emulation of asynchronous operation on top of 1282 * swap_pager_getpages(). 1283 */ 1284 static int 1285 swap_pager_getpages_async(vm_object_t object, vm_page_t *ma, int count, 1286 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1287 { 1288 int r, error; 1289 1290 r = swap_pager_getpages(object, ma, count, rbehind, rahead); 1291 VM_OBJECT_WUNLOCK(object); 1292 switch (r) { 1293 case VM_PAGER_OK: 1294 error = 0; 1295 break; 1296 case VM_PAGER_ERROR: 1297 error = EIO; 1298 break; 1299 case VM_PAGER_FAIL: 1300 error = EINVAL; 1301 break; 1302 default: 1303 panic("unhandled swap_pager_getpages() error %d", r); 1304 } 1305 (iodone)(arg, ma, count, error); 1306 VM_OBJECT_WLOCK(object); 1307 1308 return (r); 1309 } 1310 1311 /* 1312 * swap_pager_putpages: 1313 * 1314 * Assign swap (if necessary) and initiate I/O on the specified pages. 1315 * 1316 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1317 * are automatically converted to SWAP objects. 1318 * 1319 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1320 * vm_page reservation system coupled with properly written VFS devices 1321 * should ensure that no low-memory deadlock occurs. This is an area 1322 * which needs work. 1323 * 1324 * The parent has N vm_object_pip_add() references prior to 1325 * calling us and will remove references for rtvals[] that are 1326 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1327 * completion. 1328 * 1329 * The parent has soft-busy'd the pages it passes us and will unbusy 1330 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1331 * We need to unbusy the rest on I/O completion. 1332 */ 1333 static void 1334 swap_pager_putpages(vm_object_t object, vm_page_t *ma, int count, 1335 int flags, int *rtvals) 1336 { 1337 int i, n; 1338 boolean_t sync; 1339 daddr_t addr, n_free, s_free; 1340 1341 swp_pager_init_freerange(&s_free, &n_free); 1342 if (count && ma[0]->object != object) { 1343 panic("swap_pager_putpages: object mismatch %p/%p", 1344 object, 1345 ma[0]->object 1346 ); 1347 } 1348 1349 /* 1350 * Step 1 1351 * 1352 * Turn object into OBJT_SWAP 1353 * check for bogus sysops 1354 * force sync if not pageout process 1355 */ 1356 if (object->type != OBJT_SWAP) { 1357 addr = swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1358 KASSERT(addr == SWAPBLK_NONE, 1359 ("unexpected object swap block")); 1360 } 1361 VM_OBJECT_WUNLOCK(object); 1362 1363 n = 0; 1364 if (curproc != pageproc) 1365 sync = TRUE; 1366 else 1367 sync = (flags & VM_PAGER_PUT_SYNC) != 0; 1368 1369 /* 1370 * Step 2 1371 * 1372 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1373 * The page is left dirty until the pageout operation completes 1374 * successfully. 1375 */ 1376 for (i = 0; i < count; i += n) { 1377 int j; 1378 struct buf *bp; 1379 daddr_t blk; 1380 1381 /* 1382 * Maximum I/O size is limited by a number of factors. 1383 */ 1384 n = min(BLIST_MAX_ALLOC, count - i); 1385 n = min(n, nsw_cluster_max); 1386 1387 /* 1388 * Get biggest block of swap we can. If we fail, fall 1389 * back and try to allocate a smaller block. Don't go 1390 * overboard trying to allocate space if it would overly 1391 * fragment swap. 1392 */ 1393 while ( 1394 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE && 1395 n > 4 1396 ) { 1397 n >>= 1; 1398 } 1399 if (blk == SWAPBLK_NONE) { 1400 for (j = 0; j < n; ++j) 1401 rtvals[i+j] = VM_PAGER_FAIL; 1402 continue; 1403 } 1404 1405 /* 1406 * All I/O parameters have been satisfied, build the I/O 1407 * request and assign the swap space. 1408 */ 1409 if (sync != TRUE) { 1410 mtx_lock(&swbuf_mtx); 1411 while (nsw_wcount_async == 0) 1412 msleep(&nsw_wcount_async, &swbuf_mtx, PVM, 1413 "swbufa", 0); 1414 nsw_wcount_async--; 1415 mtx_unlock(&swbuf_mtx); 1416 } 1417 bp = uma_zalloc(swwbuf_zone, M_WAITOK); 1418 if (sync != TRUE) 1419 bp->b_flags = B_ASYNC; 1420 bp->b_flags |= B_PAGING; 1421 bp->b_iocmd = BIO_WRITE; 1422 1423 bp->b_rcred = crhold(thread0.td_ucred); 1424 bp->b_wcred = crhold(thread0.td_ucred); 1425 bp->b_bcount = PAGE_SIZE * n; 1426 bp->b_bufsize = PAGE_SIZE * n; 1427 bp->b_blkno = blk; 1428 1429 VM_OBJECT_WLOCK(object); 1430 for (j = 0; j < n; ++j) { 1431 vm_page_t mreq = ma[i+j]; 1432 1433 addr = swp_pager_meta_build(mreq->object, mreq->pindex, 1434 blk + j); 1435 if (addr != SWAPBLK_NONE) 1436 swp_pager_update_freerange(&s_free, &n_free, 1437 addr); 1438 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1439 mreq->oflags |= VPO_SWAPINPROG; 1440 bp->b_pages[j] = mreq; 1441 } 1442 VM_OBJECT_WUNLOCK(object); 1443 bp->b_npages = n; 1444 /* 1445 * Must set dirty range for NFS to work. 1446 */ 1447 bp->b_dirtyoff = 0; 1448 bp->b_dirtyend = bp->b_bcount; 1449 1450 VM_CNT_INC(v_swapout); 1451 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1452 1453 /* 1454 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1455 * can call the async completion routine at the end of a 1456 * synchronous I/O operation. Otherwise, our caller would 1457 * perform duplicate unbusy and wakeup operations on the page 1458 * and object, respectively. 1459 */ 1460 for (j = 0; j < n; j++) 1461 rtvals[i + j] = VM_PAGER_PEND; 1462 1463 /* 1464 * asynchronous 1465 * 1466 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1467 */ 1468 if (sync == FALSE) { 1469 bp->b_iodone = swp_pager_async_iodone; 1470 BUF_KERNPROC(bp); 1471 swp_pager_strategy(bp); 1472 continue; 1473 } 1474 1475 /* 1476 * synchronous 1477 * 1478 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1479 */ 1480 bp->b_iodone = bdone; 1481 swp_pager_strategy(bp); 1482 1483 /* 1484 * Wait for the sync I/O to complete. 1485 */ 1486 bwait(bp, PVM, "swwrt"); 1487 1488 /* 1489 * Now that we are through with the bp, we can call the 1490 * normal async completion, which frees everything up. 1491 */ 1492 swp_pager_async_iodone(bp); 1493 } 1494 VM_OBJECT_WLOCK(object); 1495 swp_pager_freeswapspace(s_free, n_free); 1496 } 1497 1498 /* 1499 * swp_pager_async_iodone: 1500 * 1501 * Completion routine for asynchronous reads and writes from/to swap. 1502 * Also called manually by synchronous code to finish up a bp. 1503 * 1504 * This routine may not sleep. 1505 */ 1506 static void 1507 swp_pager_async_iodone(struct buf *bp) 1508 { 1509 int i; 1510 vm_object_t object = NULL; 1511 1512 /* 1513 * report error 1514 */ 1515 if (bp->b_ioflags & BIO_ERROR) { 1516 printf( 1517 "swap_pager: I/O error - %s failed; blkno %ld," 1518 "size %ld, error %d\n", 1519 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1520 (long)bp->b_blkno, 1521 (long)bp->b_bcount, 1522 bp->b_error 1523 ); 1524 } 1525 1526 /* 1527 * remove the mapping for kernel virtual 1528 */ 1529 if (buf_mapped(bp)) 1530 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1531 else 1532 bp->b_data = bp->b_kvabase; 1533 1534 if (bp->b_npages) { 1535 object = bp->b_pages[0]->object; 1536 VM_OBJECT_WLOCK(object); 1537 } 1538 1539 /* 1540 * cleanup pages. If an error occurs writing to swap, we are in 1541 * very serious trouble. If it happens to be a disk error, though, 1542 * we may be able to recover by reassigning the swap later on. So 1543 * in this case we remove the m->swapblk assignment for the page 1544 * but do not free it in the rlist. The errornous block(s) are thus 1545 * never reallocated as swap. Redirty the page and continue. 1546 */ 1547 for (i = 0; i < bp->b_npages; ++i) { 1548 vm_page_t m = bp->b_pages[i]; 1549 1550 m->oflags &= ~VPO_SWAPINPROG; 1551 if (m->oflags & VPO_SWAPSLEEP) { 1552 m->oflags &= ~VPO_SWAPSLEEP; 1553 wakeup(&object->paging_in_progress); 1554 } 1555 1556 if (bp->b_ioflags & BIO_ERROR) { 1557 /* 1558 * If an error occurs I'd love to throw the swapblk 1559 * away without freeing it back to swapspace, so it 1560 * can never be used again. But I can't from an 1561 * interrupt. 1562 */ 1563 if (bp->b_iocmd == BIO_READ) { 1564 /* 1565 * NOTE: for reads, m->dirty will probably 1566 * be overridden by the original caller of 1567 * getpages so don't play cute tricks here. 1568 */ 1569 m->valid = 0; 1570 } else { 1571 /* 1572 * If a write error occurs, reactivate page 1573 * so it doesn't clog the inactive list, 1574 * then finish the I/O. 1575 */ 1576 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1577 vm_page_lock(m); 1578 vm_page_activate(m); 1579 vm_page_unlock(m); 1580 vm_page_sunbusy(m); 1581 } 1582 } else if (bp->b_iocmd == BIO_READ) { 1583 /* 1584 * NOTE: for reads, m->dirty will probably be 1585 * overridden by the original caller of getpages so 1586 * we cannot set them in order to free the underlying 1587 * swap in a low-swap situation. I don't think we'd 1588 * want to do that anyway, but it was an optimization 1589 * that existed in the old swapper for a time before 1590 * it got ripped out due to precisely this problem. 1591 */ 1592 KASSERT(!pmap_page_is_mapped(m), 1593 ("swp_pager_async_iodone: page %p is mapped", m)); 1594 KASSERT(m->dirty == 0, 1595 ("swp_pager_async_iodone: page %p is dirty", m)); 1596 1597 m->valid = VM_PAGE_BITS_ALL; 1598 if (i < bp->b_pgbefore || 1599 i >= bp->b_npages - bp->b_pgafter) 1600 vm_page_readahead_finish(m); 1601 } else { 1602 /* 1603 * For write success, clear the dirty 1604 * status, then finish the I/O ( which decrements the 1605 * busy count and possibly wakes waiter's up ). 1606 * A page is only written to swap after a period of 1607 * inactivity. Therefore, we do not expect it to be 1608 * reused. 1609 */ 1610 KASSERT(!pmap_page_is_write_mapped(m), 1611 ("swp_pager_async_iodone: page %p is not write" 1612 " protected", m)); 1613 vm_page_undirty(m); 1614 vm_page_lock(m); 1615 vm_page_deactivate_noreuse(m); 1616 vm_page_unlock(m); 1617 vm_page_sunbusy(m); 1618 } 1619 } 1620 1621 /* 1622 * adjust pip. NOTE: the original parent may still have its own 1623 * pip refs on the object. 1624 */ 1625 if (object != NULL) { 1626 vm_object_pip_wakeupn(object, bp->b_npages); 1627 VM_OBJECT_WUNLOCK(object); 1628 } 1629 1630 /* 1631 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1632 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1633 * trigger a KASSERT in relpbuf(). 1634 */ 1635 if (bp->b_vp) { 1636 bp->b_vp = NULL; 1637 bp->b_bufobj = NULL; 1638 } 1639 /* 1640 * release the physical I/O buffer 1641 */ 1642 if (bp->b_flags & B_ASYNC) { 1643 mtx_lock(&swbuf_mtx); 1644 if (++nsw_wcount_async == 1) 1645 wakeup(&nsw_wcount_async); 1646 mtx_unlock(&swbuf_mtx); 1647 } 1648 uma_zfree((bp->b_iocmd == BIO_READ) ? swrbuf_zone : swwbuf_zone, bp); 1649 } 1650 1651 int 1652 swap_pager_nswapdev(void) 1653 { 1654 1655 return (nswapdev); 1656 } 1657 1658 /* 1659 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in 1660 * 1661 * This routine dissociates the page at the given index within an object 1662 * from its backing store, paging it in if it does not reside in memory. 1663 * If the page is paged in, it is marked dirty and placed in the laundry 1664 * queue. The page is marked dirty because it no longer has backing 1665 * store. It is placed in the laundry queue because it has not been 1666 * accessed recently. Otherwise, it would already reside in memory. 1667 * 1668 * We also attempt to swap in all other pages in the swap block. 1669 * However, we only guarantee that the one at the specified index is 1670 * paged in. 1671 * 1672 * XXX - The code to page the whole block in doesn't work, so we 1673 * revert to the one-by-one behavior for now. Sigh. 1674 */ 1675 static inline void 1676 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex) 1677 { 1678 vm_page_t m; 1679 1680 vm_object_pip_add(object, 1); 1681 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL); 1682 if (m->valid == VM_PAGE_BITS_ALL) { 1683 vm_object_pip_wakeup(object); 1684 vm_page_dirty(m); 1685 #ifdef INVARIANTS 1686 vm_page_lock(m); 1687 if (m->wire_count == 0 && m->queue == PQ_NONE) 1688 panic("page %p is neither wired nor queued", m); 1689 vm_page_unlock(m); 1690 #endif 1691 vm_page_xunbusy(m); 1692 vm_pager_page_unswapped(m); 1693 return; 1694 } 1695 1696 if (swap_pager_getpages(object, &m, 1, NULL, NULL) != VM_PAGER_OK) 1697 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/ 1698 vm_object_pip_wakeup(object); 1699 vm_page_dirty(m); 1700 vm_page_lock(m); 1701 vm_page_launder(m); 1702 vm_page_unlock(m); 1703 vm_page_xunbusy(m); 1704 vm_pager_page_unswapped(m); 1705 } 1706 1707 /* 1708 * swap_pager_swapoff: 1709 * 1710 * Page in all of the pages that have been paged out to the 1711 * given device. The corresponding blocks in the bitmap must be 1712 * marked as allocated and the device must be flagged SW_CLOSING. 1713 * There may be no processes swapped out to the device. 1714 * 1715 * This routine may block. 1716 */ 1717 static void 1718 swap_pager_swapoff(struct swdevt *sp) 1719 { 1720 struct swblk *sb; 1721 vm_object_t object; 1722 vm_pindex_t pi; 1723 int i, retries; 1724 1725 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 1726 1727 retries = 0; 1728 full_rescan: 1729 mtx_lock(&vm_object_list_mtx); 1730 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1731 if (object->type != OBJT_SWAP) 1732 continue; 1733 mtx_unlock(&vm_object_list_mtx); 1734 /* Depends on type-stability. */ 1735 VM_OBJECT_WLOCK(object); 1736 1737 /* 1738 * Dead objects are eventually terminated on their own. 1739 */ 1740 if ((object->flags & OBJ_DEAD) != 0) 1741 goto next_obj; 1742 1743 /* 1744 * Sync with fences placed after pctrie 1745 * initialization. We must not access pctrie below 1746 * unless we checked that our object is swap and not 1747 * dead. 1748 */ 1749 atomic_thread_fence_acq(); 1750 if (object->type != OBJT_SWAP) 1751 goto next_obj; 1752 1753 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1754 &object->un_pager.swp.swp_blks, pi)) != NULL; ) { 1755 pi = sb->p + SWAP_META_PAGES; 1756 for (i = 0; i < SWAP_META_PAGES; i++) { 1757 if (sb->d[i] == SWAPBLK_NONE) 1758 continue; 1759 if (swp_pager_isondev(sb->d[i], sp)) 1760 swp_pager_force_pagein(object, 1761 sb->p + i); 1762 } 1763 } 1764 next_obj: 1765 VM_OBJECT_WUNLOCK(object); 1766 mtx_lock(&vm_object_list_mtx); 1767 } 1768 mtx_unlock(&vm_object_list_mtx); 1769 1770 if (sp->sw_used) { 1771 /* 1772 * Objects may be locked or paging to the device being 1773 * removed, so we will miss their pages and need to 1774 * make another pass. We have marked this device as 1775 * SW_CLOSING, so the activity should finish soon. 1776 */ 1777 retries++; 1778 if (retries > 100) { 1779 panic("swapoff: failed to locate %d swap blocks", 1780 sp->sw_used); 1781 } 1782 pause("swpoff", hz / 20); 1783 goto full_rescan; 1784 } 1785 EVENTHANDLER_INVOKE(swapoff, sp); 1786 } 1787 1788 /************************************************************************ 1789 * SWAP META DATA * 1790 ************************************************************************ 1791 * 1792 * These routines manipulate the swap metadata stored in the 1793 * OBJT_SWAP object. 1794 * 1795 * Swap metadata is implemented with a global hash and not directly 1796 * linked into the object. Instead the object simply contains 1797 * appropriate tracking counters. 1798 */ 1799 1800 /* 1801 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? 1802 */ 1803 static bool 1804 swp_pager_swblk_empty(struct swblk *sb, int start, int limit) 1805 { 1806 int i; 1807 1808 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); 1809 for (i = start; i < limit; i++) { 1810 if (sb->d[i] != SWAPBLK_NONE) 1811 return (false); 1812 } 1813 return (true); 1814 } 1815 1816 /* 1817 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1818 * 1819 * We first convert the object to a swap object if it is a default 1820 * object. 1821 * 1822 * The specified swapblk is added to the object's swap metadata. If 1823 * the swapblk is not valid, it is freed instead. Any previously 1824 * assigned swapblk is returned. 1825 */ 1826 static daddr_t 1827 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1828 { 1829 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 1830 struct swblk *sb, *sb1; 1831 vm_pindex_t modpi, rdpi; 1832 daddr_t prev_swapblk; 1833 int error, i; 1834 1835 VM_OBJECT_ASSERT_WLOCKED(object); 1836 1837 /* 1838 * Convert default object to swap object if necessary 1839 */ 1840 if (object->type != OBJT_SWAP) { 1841 pctrie_init(&object->un_pager.swp.swp_blks); 1842 1843 /* 1844 * Ensure that swap_pager_swapoff()'s iteration over 1845 * object_list does not see a garbage pctrie. 1846 */ 1847 atomic_thread_fence_rel(); 1848 1849 object->type = OBJT_SWAP; 1850 KASSERT(object->handle == NULL, ("default pager with handle")); 1851 } 1852 1853 rdpi = rounddown(pindex, SWAP_META_PAGES); 1854 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi); 1855 if (sb == NULL) { 1856 if (swapblk == SWAPBLK_NONE) 1857 return (SWAPBLK_NONE); 1858 for (;;) { 1859 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 1860 pageproc ? M_USE_RESERVE : 0)); 1861 if (sb != NULL) { 1862 sb->p = rdpi; 1863 for (i = 0; i < SWAP_META_PAGES; i++) 1864 sb->d[i] = SWAPBLK_NONE; 1865 if (atomic_cmpset_int(&swblk_zone_exhausted, 1866 1, 0)) 1867 printf("swblk zone ok\n"); 1868 break; 1869 } 1870 VM_OBJECT_WUNLOCK(object); 1871 if (uma_zone_exhausted(swblk_zone)) { 1872 if (atomic_cmpset_int(&swblk_zone_exhausted, 1873 0, 1)) 1874 printf("swap blk zone exhausted, " 1875 "increase kern.maxswzone\n"); 1876 vm_pageout_oom(VM_OOM_SWAPZ); 1877 pause("swzonxb", 10); 1878 } else 1879 uma_zwait(swblk_zone); 1880 VM_OBJECT_WLOCK(object); 1881 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 1882 rdpi); 1883 if (sb != NULL) 1884 /* 1885 * Somebody swapped out a nearby page, 1886 * allocating swblk at the rdpi index, 1887 * while we dropped the object lock. 1888 */ 1889 goto allocated; 1890 } 1891 for (;;) { 1892 error = SWAP_PCTRIE_INSERT( 1893 &object->un_pager.swp.swp_blks, sb); 1894 if (error == 0) { 1895 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1896 1, 0)) 1897 printf("swpctrie zone ok\n"); 1898 break; 1899 } 1900 VM_OBJECT_WUNLOCK(object); 1901 if (uma_zone_exhausted(swpctrie_zone)) { 1902 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1903 0, 1)) 1904 printf("swap pctrie zone exhausted, " 1905 "increase kern.maxswzone\n"); 1906 vm_pageout_oom(VM_OOM_SWAPZ); 1907 pause("swzonxp", 10); 1908 } else 1909 uma_zwait(swpctrie_zone); 1910 VM_OBJECT_WLOCK(object); 1911 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 1912 rdpi); 1913 if (sb1 != NULL) { 1914 uma_zfree(swblk_zone, sb); 1915 sb = sb1; 1916 goto allocated; 1917 } 1918 } 1919 } 1920 allocated: 1921 MPASS(sb->p == rdpi); 1922 1923 modpi = pindex % SWAP_META_PAGES; 1924 /* Return prior contents of metadata. */ 1925 prev_swapblk = sb->d[modpi]; 1926 /* Enter block into metadata. */ 1927 sb->d[modpi] = swapblk; 1928 1929 /* 1930 * Free the swblk if we end up with the empty page run. 1931 */ 1932 if (swapblk == SWAPBLK_NONE && 1933 swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 1934 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, rdpi); 1935 uma_zfree(swblk_zone, sb); 1936 } 1937 return (prev_swapblk); 1938 } 1939 1940 /* 1941 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 1942 * 1943 * The requested range of blocks is freed, with any associated swap 1944 * returned to the swap bitmap. 1945 * 1946 * This routine will free swap metadata structures as they are cleaned 1947 * out. This routine does *NOT* operate on swap metadata associated 1948 * with resident pages. 1949 */ 1950 static void 1951 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count) 1952 { 1953 struct swblk *sb; 1954 daddr_t n_free, s_free; 1955 vm_pindex_t last; 1956 int i, limit, start; 1957 1958 VM_OBJECT_ASSERT_WLOCKED(object); 1959 if (object->type != OBJT_SWAP || count == 0) 1960 return; 1961 1962 swp_pager_init_freerange(&s_free, &n_free); 1963 last = pindex + count; 1964 for (;;) { 1965 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 1966 rounddown(pindex, SWAP_META_PAGES)); 1967 if (sb == NULL || sb->p >= last) 1968 break; 1969 start = pindex > sb->p ? pindex - sb->p : 0; 1970 limit = last - sb->p < SWAP_META_PAGES ? last - sb->p : 1971 SWAP_META_PAGES; 1972 for (i = start; i < limit; i++) { 1973 if (sb->d[i] == SWAPBLK_NONE) 1974 continue; 1975 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]); 1976 sb->d[i] = SWAPBLK_NONE; 1977 } 1978 pindex = sb->p + SWAP_META_PAGES; 1979 if (swp_pager_swblk_empty(sb, 0, start) && 1980 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 1981 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, 1982 sb->p); 1983 uma_zfree(swblk_zone, sb); 1984 } 1985 } 1986 swp_pager_freeswapspace(s_free, n_free); 1987 } 1988 1989 /* 1990 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 1991 * 1992 * This routine locates and destroys all swap metadata associated with 1993 * an object. 1994 */ 1995 static void 1996 swp_pager_meta_free_all(vm_object_t object) 1997 { 1998 struct swblk *sb; 1999 daddr_t n_free, s_free; 2000 vm_pindex_t pindex; 2001 int i; 2002 2003 VM_OBJECT_ASSERT_WLOCKED(object); 2004 if (object->type != OBJT_SWAP) 2005 return; 2006 2007 swp_pager_init_freerange(&s_free, &n_free); 2008 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 2009 &object->un_pager.swp.swp_blks, pindex)) != NULL;) { 2010 pindex = sb->p + SWAP_META_PAGES; 2011 for (i = 0; i < SWAP_META_PAGES; i++) { 2012 if (sb->d[i] == SWAPBLK_NONE) 2013 continue; 2014 swp_pager_update_freerange(&s_free, &n_free, sb->d[i]); 2015 } 2016 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 2017 uma_zfree(swblk_zone, sb); 2018 } 2019 swp_pager_freeswapspace(s_free, n_free); 2020 } 2021 2022 /* 2023 * SWP_PAGER_METACTL() - misc control of swap meta data. 2024 * 2025 * This routine is capable of looking up, or removing swapblk 2026 * assignments in the swap meta data. It returns the swapblk being 2027 * looked-up, popped, or SWAPBLK_NONE if the block was invalid. 2028 * 2029 * When acting on a busy resident page and paging is in progress, we 2030 * have to wait until paging is complete but otherwise can act on the 2031 * busy page. 2032 * 2033 * SWM_POP remove from meta data but do not free it 2034 */ 2035 static daddr_t 2036 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags) 2037 { 2038 struct swblk *sb; 2039 daddr_t r1; 2040 2041 if ((flags & SWM_POP) != 0) 2042 VM_OBJECT_ASSERT_WLOCKED(object); 2043 else 2044 VM_OBJECT_ASSERT_LOCKED(object); 2045 2046 /* 2047 * The meta data only exists if the object is OBJT_SWAP 2048 * and even then might not be allocated yet. 2049 */ 2050 if (object->type != OBJT_SWAP) 2051 return (SWAPBLK_NONE); 2052 2053 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2054 rounddown(pindex, SWAP_META_PAGES)); 2055 if (sb == NULL) 2056 return (SWAPBLK_NONE); 2057 r1 = sb->d[pindex % SWAP_META_PAGES]; 2058 if (r1 == SWAPBLK_NONE) 2059 return (SWAPBLK_NONE); 2060 if ((flags & SWM_POP) != 0) { 2061 sb->d[pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 2062 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 2063 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, 2064 rounddown(pindex, SWAP_META_PAGES)); 2065 uma_zfree(swblk_zone, sb); 2066 } 2067 } 2068 return (r1); 2069 } 2070 2071 /* 2072 * Returns the least page index which is greater than or equal to the 2073 * parameter pindex and for which there is a swap block allocated. 2074 * Returns object's size if the object's type is not swap or if there 2075 * are no allocated swap blocks for the object after the requested 2076 * pindex. 2077 */ 2078 vm_pindex_t 2079 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2080 { 2081 struct swblk *sb; 2082 int i; 2083 2084 VM_OBJECT_ASSERT_LOCKED(object); 2085 if (object->type != OBJT_SWAP) 2086 return (object->size); 2087 2088 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2089 rounddown(pindex, SWAP_META_PAGES)); 2090 if (sb == NULL) 2091 return (object->size); 2092 if (sb->p < pindex) { 2093 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2094 if (sb->d[i] != SWAPBLK_NONE) 2095 return (sb->p + i); 2096 } 2097 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2098 roundup(pindex, SWAP_META_PAGES)); 2099 if (sb == NULL) 2100 return (object->size); 2101 } 2102 for (i = 0; i < SWAP_META_PAGES; i++) { 2103 if (sb->d[i] != SWAPBLK_NONE) 2104 return (sb->p + i); 2105 } 2106 2107 /* 2108 * We get here if a swblk is present in the trie but it 2109 * doesn't map any blocks. 2110 */ 2111 MPASS(0); 2112 return (object->size); 2113 } 2114 2115 /* 2116 * System call swapon(name) enables swapping on device name, 2117 * which must be in the swdevsw. Return EBUSY 2118 * if already swapping on this device. 2119 */ 2120 #ifndef _SYS_SYSPROTO_H_ 2121 struct swapon_args { 2122 char *name; 2123 }; 2124 #endif 2125 2126 /* 2127 * MPSAFE 2128 */ 2129 /* ARGSUSED */ 2130 int 2131 sys_swapon(struct thread *td, struct swapon_args *uap) 2132 { 2133 struct vattr attr; 2134 struct vnode *vp; 2135 struct nameidata nd; 2136 int error; 2137 2138 error = priv_check(td, PRIV_SWAPON); 2139 if (error) 2140 return (error); 2141 2142 sx_xlock(&swdev_syscall_lock); 2143 2144 /* 2145 * Swap metadata may not fit in the KVM if we have physical 2146 * memory of >1GB. 2147 */ 2148 if (swblk_zone == NULL) { 2149 error = ENOMEM; 2150 goto done; 2151 } 2152 2153 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2154 uap->name, td); 2155 error = namei(&nd); 2156 if (error) 2157 goto done; 2158 2159 NDFREE(&nd, NDF_ONLY_PNBUF); 2160 vp = nd.ni_vp; 2161 2162 if (vn_isdisk(vp, &error)) { 2163 error = swapongeom(vp); 2164 } else if (vp->v_type == VREG && 2165 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2166 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2167 /* 2168 * Allow direct swapping to NFS regular files in the same 2169 * way that nfs_mountroot() sets up diskless swapping. 2170 */ 2171 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2172 } 2173 2174 if (error) 2175 vrele(vp); 2176 done: 2177 sx_xunlock(&swdev_syscall_lock); 2178 return (error); 2179 } 2180 2181 /* 2182 * Check that the total amount of swap currently configured does not 2183 * exceed half the theoretical maximum. If it does, print a warning 2184 * message. 2185 */ 2186 static void 2187 swapon_check_swzone(void) 2188 { 2189 unsigned long maxpages, npages; 2190 2191 npages = swap_total; 2192 /* absolute maximum we can handle assuming 100% efficiency */ 2193 maxpages = uma_zone_get_max(swblk_zone) * SWAP_META_PAGES; 2194 2195 /* recommend using no more than half that amount */ 2196 if (npages > maxpages / 2) { 2197 printf("warning: total configured swap (%lu pages) " 2198 "exceeds maximum recommended amount (%lu pages).\n", 2199 npages, maxpages / 2); 2200 printf("warning: increase kern.maxswzone " 2201 "or reduce amount of swap.\n"); 2202 } 2203 } 2204 2205 static void 2206 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2207 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2208 { 2209 struct swdevt *sp, *tsp; 2210 swblk_t dvbase; 2211 u_long mblocks; 2212 2213 /* 2214 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2215 * First chop nblks off to page-align it, then convert. 2216 * 2217 * sw->sw_nblks is in page-sized chunks now too. 2218 */ 2219 nblks &= ~(ctodb(1) - 1); 2220 nblks = dbtoc(nblks); 2221 2222 /* 2223 * If we go beyond this, we get overflows in the radix 2224 * tree bitmap code. 2225 */ 2226 mblocks = 0x40000000 / BLIST_META_RADIX; 2227 if (nblks > mblocks) { 2228 printf( 2229 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2230 mblocks / 1024 / 1024 * PAGE_SIZE); 2231 nblks = mblocks; 2232 } 2233 2234 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2235 sp->sw_vp = vp; 2236 sp->sw_id = id; 2237 sp->sw_dev = dev; 2238 sp->sw_flags = 0; 2239 sp->sw_nblks = nblks; 2240 sp->sw_used = 0; 2241 sp->sw_strategy = strategy; 2242 sp->sw_close = close; 2243 sp->sw_flags = flags; 2244 2245 sp->sw_blist = blist_create(nblks, M_WAITOK); 2246 /* 2247 * Do not free the first two block in order to avoid overwriting 2248 * any bsd label at the front of the partition 2249 */ 2250 blist_free(sp->sw_blist, 2, nblks - 2); 2251 2252 dvbase = 0; 2253 mtx_lock(&sw_dev_mtx); 2254 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2255 if (tsp->sw_end >= dvbase) { 2256 /* 2257 * We put one uncovered page between the devices 2258 * in order to definitively prevent any cross-device 2259 * I/O requests 2260 */ 2261 dvbase = tsp->sw_end + 1; 2262 } 2263 } 2264 sp->sw_first = dvbase; 2265 sp->sw_end = dvbase + nblks; 2266 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2267 nswapdev++; 2268 swap_pager_avail += nblks - 2; 2269 swap_total += nblks; 2270 swapon_check_swzone(); 2271 swp_sizecheck(); 2272 mtx_unlock(&sw_dev_mtx); 2273 EVENTHANDLER_INVOKE(swapon, sp); 2274 } 2275 2276 /* 2277 * SYSCALL: swapoff(devname) 2278 * 2279 * Disable swapping on the given device. 2280 * 2281 * XXX: Badly designed system call: it should use a device index 2282 * rather than filename as specification. We keep sw_vp around 2283 * only to make this work. 2284 */ 2285 #ifndef _SYS_SYSPROTO_H_ 2286 struct swapoff_args { 2287 char *name; 2288 }; 2289 #endif 2290 2291 /* 2292 * MPSAFE 2293 */ 2294 /* ARGSUSED */ 2295 int 2296 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2297 { 2298 struct vnode *vp; 2299 struct nameidata nd; 2300 struct swdevt *sp; 2301 int error; 2302 2303 error = priv_check(td, PRIV_SWAPOFF); 2304 if (error) 2305 return (error); 2306 2307 sx_xlock(&swdev_syscall_lock); 2308 2309 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2310 td); 2311 error = namei(&nd); 2312 if (error) 2313 goto done; 2314 NDFREE(&nd, NDF_ONLY_PNBUF); 2315 vp = nd.ni_vp; 2316 2317 mtx_lock(&sw_dev_mtx); 2318 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2319 if (sp->sw_vp == vp) 2320 break; 2321 } 2322 mtx_unlock(&sw_dev_mtx); 2323 if (sp == NULL) { 2324 error = EINVAL; 2325 goto done; 2326 } 2327 error = swapoff_one(sp, td->td_ucred); 2328 done: 2329 sx_xunlock(&swdev_syscall_lock); 2330 return (error); 2331 } 2332 2333 static int 2334 swapoff_one(struct swdevt *sp, struct ucred *cred) 2335 { 2336 u_long nblks; 2337 #ifdef MAC 2338 int error; 2339 #endif 2340 2341 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2342 #ifdef MAC 2343 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2344 error = mac_system_check_swapoff(cred, sp->sw_vp); 2345 (void) VOP_UNLOCK(sp->sw_vp, 0); 2346 if (error != 0) 2347 return (error); 2348 #endif 2349 nblks = sp->sw_nblks; 2350 2351 /* 2352 * We can turn off this swap device safely only if the 2353 * available virtual memory in the system will fit the amount 2354 * of data we will have to page back in, plus an epsilon so 2355 * the system doesn't become critically low on swap space. 2356 */ 2357 if (vm_free_count() + swap_pager_avail < nblks + nswap_lowat) 2358 return (ENOMEM); 2359 2360 /* 2361 * Prevent further allocations on this device. 2362 */ 2363 mtx_lock(&sw_dev_mtx); 2364 sp->sw_flags |= SW_CLOSING; 2365 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2366 swap_total -= nblks; 2367 mtx_unlock(&sw_dev_mtx); 2368 2369 /* 2370 * Page in the contents of the device and close it. 2371 */ 2372 swap_pager_swapoff(sp); 2373 2374 sp->sw_close(curthread, sp); 2375 mtx_lock(&sw_dev_mtx); 2376 sp->sw_id = NULL; 2377 TAILQ_REMOVE(&swtailq, sp, sw_list); 2378 nswapdev--; 2379 if (nswapdev == 0) { 2380 swap_pager_full = 2; 2381 swap_pager_almost_full = 1; 2382 } 2383 if (swdevhd == sp) 2384 swdevhd = NULL; 2385 mtx_unlock(&sw_dev_mtx); 2386 blist_destroy(sp->sw_blist); 2387 free(sp, M_VMPGDATA); 2388 return (0); 2389 } 2390 2391 void 2392 swapoff_all(void) 2393 { 2394 struct swdevt *sp, *spt; 2395 const char *devname; 2396 int error; 2397 2398 sx_xlock(&swdev_syscall_lock); 2399 2400 mtx_lock(&sw_dev_mtx); 2401 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2402 mtx_unlock(&sw_dev_mtx); 2403 if (vn_isdisk(sp->sw_vp, NULL)) 2404 devname = devtoname(sp->sw_vp->v_rdev); 2405 else 2406 devname = "[file]"; 2407 error = swapoff_one(sp, thread0.td_ucred); 2408 if (error != 0) { 2409 printf("Cannot remove swap device %s (error=%d), " 2410 "skipping.\n", devname, error); 2411 } else if (bootverbose) { 2412 printf("Swap device %s removed.\n", devname); 2413 } 2414 mtx_lock(&sw_dev_mtx); 2415 } 2416 mtx_unlock(&sw_dev_mtx); 2417 2418 sx_xunlock(&swdev_syscall_lock); 2419 } 2420 2421 void 2422 swap_pager_status(int *total, int *used) 2423 { 2424 struct swdevt *sp; 2425 2426 *total = 0; 2427 *used = 0; 2428 mtx_lock(&sw_dev_mtx); 2429 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2430 *total += sp->sw_nblks; 2431 *used += sp->sw_used; 2432 } 2433 mtx_unlock(&sw_dev_mtx); 2434 } 2435 2436 int 2437 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2438 { 2439 struct swdevt *sp; 2440 const char *tmp_devname; 2441 int error, n; 2442 2443 n = 0; 2444 error = ENOENT; 2445 mtx_lock(&sw_dev_mtx); 2446 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2447 if (n != name) { 2448 n++; 2449 continue; 2450 } 2451 xs->xsw_version = XSWDEV_VERSION; 2452 xs->xsw_dev = sp->sw_dev; 2453 xs->xsw_flags = sp->sw_flags; 2454 xs->xsw_nblks = sp->sw_nblks; 2455 xs->xsw_used = sp->sw_used; 2456 if (devname != NULL) { 2457 if (vn_isdisk(sp->sw_vp, NULL)) 2458 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2459 else 2460 tmp_devname = "[file]"; 2461 strncpy(devname, tmp_devname, len); 2462 } 2463 error = 0; 2464 break; 2465 } 2466 mtx_unlock(&sw_dev_mtx); 2467 return (error); 2468 } 2469 2470 #if defined(COMPAT_FREEBSD11) 2471 #define XSWDEV_VERSION_11 1 2472 struct xswdev11 { 2473 u_int xsw_version; 2474 uint32_t xsw_dev; 2475 int xsw_flags; 2476 int xsw_nblks; 2477 int xsw_used; 2478 }; 2479 #endif 2480 2481 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2482 struct xswdev32 { 2483 u_int xsw_version; 2484 u_int xsw_dev1, xsw_dev2; 2485 int xsw_flags; 2486 int xsw_nblks; 2487 int xsw_used; 2488 }; 2489 #endif 2490 2491 static int 2492 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2493 { 2494 struct xswdev xs; 2495 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2496 struct xswdev32 xs32; 2497 #endif 2498 #if defined(COMPAT_FREEBSD11) 2499 struct xswdev11 xs11; 2500 #endif 2501 int error; 2502 2503 if (arg2 != 1) /* name length */ 2504 return (EINVAL); 2505 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2506 if (error != 0) 2507 return (error); 2508 #if defined(__amd64__) && defined(COMPAT_FREEBSD32) 2509 if (req->oldlen == sizeof(xs32)) { 2510 xs32.xsw_version = XSWDEV_VERSION; 2511 xs32.xsw_dev1 = xs.xsw_dev; 2512 xs32.xsw_dev2 = xs.xsw_dev >> 32; 2513 xs32.xsw_flags = xs.xsw_flags; 2514 xs32.xsw_nblks = xs.xsw_nblks; 2515 xs32.xsw_used = xs.xsw_used; 2516 error = SYSCTL_OUT(req, &xs32, sizeof(xs32)); 2517 return (error); 2518 } 2519 #endif 2520 #if defined(COMPAT_FREEBSD11) 2521 if (req->oldlen == sizeof(xs11)) { 2522 xs11.xsw_version = XSWDEV_VERSION_11; 2523 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2524 xs11.xsw_flags = xs.xsw_flags; 2525 xs11.xsw_nblks = xs.xsw_nblks; 2526 xs11.xsw_used = xs.xsw_used; 2527 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2528 return (error); 2529 } 2530 #endif 2531 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2532 return (error); 2533 } 2534 2535 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2536 "Number of swap devices"); 2537 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2538 sysctl_vm_swap_info, 2539 "Swap statistics by device"); 2540 2541 /* 2542 * Count the approximate swap usage in pages for a vmspace. The 2543 * shadowed or not yet copied on write swap blocks are not accounted. 2544 * The map must be locked. 2545 */ 2546 long 2547 vmspace_swap_count(struct vmspace *vmspace) 2548 { 2549 vm_map_t map; 2550 vm_map_entry_t cur; 2551 vm_object_t object; 2552 struct swblk *sb; 2553 vm_pindex_t e, pi; 2554 long count; 2555 int i; 2556 2557 map = &vmspace->vm_map; 2558 count = 0; 2559 2560 for (cur = map->header.next; cur != &map->header; cur = cur->next) { 2561 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 2562 continue; 2563 object = cur->object.vm_object; 2564 if (object == NULL || object->type != OBJT_SWAP) 2565 continue; 2566 VM_OBJECT_RLOCK(object); 2567 if (object->type != OBJT_SWAP) 2568 goto unlock; 2569 pi = OFF_TO_IDX(cur->offset); 2570 e = pi + OFF_TO_IDX(cur->end - cur->start); 2571 for (;; pi = sb->p + SWAP_META_PAGES) { 2572 sb = SWAP_PCTRIE_LOOKUP_GE( 2573 &object->un_pager.swp.swp_blks, pi); 2574 if (sb == NULL || sb->p >= e) 2575 break; 2576 for (i = 0; i < SWAP_META_PAGES; i++) { 2577 if (sb->p + i < e && 2578 sb->d[i] != SWAPBLK_NONE) 2579 count++; 2580 } 2581 } 2582 unlock: 2583 VM_OBJECT_RUNLOCK(object); 2584 } 2585 return (count); 2586 } 2587 2588 /* 2589 * GEOM backend 2590 * 2591 * Swapping onto disk devices. 2592 * 2593 */ 2594 2595 static g_orphan_t swapgeom_orphan; 2596 2597 static struct g_class g_swap_class = { 2598 .name = "SWAP", 2599 .version = G_VERSION, 2600 .orphan = swapgeom_orphan, 2601 }; 2602 2603 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2604 2605 2606 static void 2607 swapgeom_close_ev(void *arg, int flags) 2608 { 2609 struct g_consumer *cp; 2610 2611 cp = arg; 2612 g_access(cp, -1, -1, 0); 2613 g_detach(cp); 2614 g_destroy_consumer(cp); 2615 } 2616 2617 /* 2618 * Add a reference to the g_consumer for an inflight transaction. 2619 */ 2620 static void 2621 swapgeom_acquire(struct g_consumer *cp) 2622 { 2623 2624 mtx_assert(&sw_dev_mtx, MA_OWNED); 2625 cp->index++; 2626 } 2627 2628 /* 2629 * Remove a reference from the g_consumer. Post a close event if all 2630 * references go away, since the function might be called from the 2631 * biodone context. 2632 */ 2633 static void 2634 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2635 { 2636 2637 mtx_assert(&sw_dev_mtx, MA_OWNED); 2638 cp->index--; 2639 if (cp->index == 0) { 2640 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2641 sp->sw_id = NULL; 2642 } 2643 } 2644 2645 static void 2646 swapgeom_done(struct bio *bp2) 2647 { 2648 struct swdevt *sp; 2649 struct buf *bp; 2650 struct g_consumer *cp; 2651 2652 bp = bp2->bio_caller2; 2653 cp = bp2->bio_from; 2654 bp->b_ioflags = bp2->bio_flags; 2655 if (bp2->bio_error) 2656 bp->b_ioflags |= BIO_ERROR; 2657 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2658 bp->b_error = bp2->bio_error; 2659 bp->b_caller1 = NULL; 2660 bufdone(bp); 2661 sp = bp2->bio_caller1; 2662 mtx_lock(&sw_dev_mtx); 2663 swapgeom_release(cp, sp); 2664 mtx_unlock(&sw_dev_mtx); 2665 g_destroy_bio(bp2); 2666 } 2667 2668 static void 2669 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2670 { 2671 struct bio *bio; 2672 struct g_consumer *cp; 2673 2674 mtx_lock(&sw_dev_mtx); 2675 cp = sp->sw_id; 2676 if (cp == NULL) { 2677 mtx_unlock(&sw_dev_mtx); 2678 bp->b_error = ENXIO; 2679 bp->b_ioflags |= BIO_ERROR; 2680 bufdone(bp); 2681 return; 2682 } 2683 swapgeom_acquire(cp); 2684 mtx_unlock(&sw_dev_mtx); 2685 if (bp->b_iocmd == BIO_WRITE) 2686 bio = g_new_bio(); 2687 else 2688 bio = g_alloc_bio(); 2689 if (bio == NULL) { 2690 mtx_lock(&sw_dev_mtx); 2691 swapgeom_release(cp, sp); 2692 mtx_unlock(&sw_dev_mtx); 2693 bp->b_error = ENOMEM; 2694 bp->b_ioflags |= BIO_ERROR; 2695 bufdone(bp); 2696 return; 2697 } 2698 2699 bp->b_caller1 = bio; 2700 bio->bio_caller1 = sp; 2701 bio->bio_caller2 = bp; 2702 bio->bio_cmd = bp->b_iocmd; 2703 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2704 bio->bio_length = bp->b_bcount; 2705 bio->bio_done = swapgeom_done; 2706 if (!buf_mapped(bp)) { 2707 bio->bio_ma = bp->b_pages; 2708 bio->bio_data = unmapped_buf; 2709 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2710 bio->bio_ma_n = bp->b_npages; 2711 bio->bio_flags |= BIO_UNMAPPED; 2712 } else { 2713 bio->bio_data = bp->b_data; 2714 bio->bio_ma = NULL; 2715 } 2716 g_io_request(bio, cp); 2717 return; 2718 } 2719 2720 static void 2721 swapgeom_orphan(struct g_consumer *cp) 2722 { 2723 struct swdevt *sp; 2724 int destroy; 2725 2726 mtx_lock(&sw_dev_mtx); 2727 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2728 if (sp->sw_id == cp) { 2729 sp->sw_flags |= SW_CLOSING; 2730 break; 2731 } 2732 } 2733 /* 2734 * Drop reference we were created with. Do directly since we're in a 2735 * special context where we don't have to queue the call to 2736 * swapgeom_close_ev(). 2737 */ 2738 cp->index--; 2739 destroy = ((sp != NULL) && (cp->index == 0)); 2740 if (destroy) 2741 sp->sw_id = NULL; 2742 mtx_unlock(&sw_dev_mtx); 2743 if (destroy) 2744 swapgeom_close_ev(cp, 0); 2745 } 2746 2747 static void 2748 swapgeom_close(struct thread *td, struct swdevt *sw) 2749 { 2750 struct g_consumer *cp; 2751 2752 mtx_lock(&sw_dev_mtx); 2753 cp = sw->sw_id; 2754 sw->sw_id = NULL; 2755 mtx_unlock(&sw_dev_mtx); 2756 2757 /* 2758 * swapgeom_close() may be called from the biodone context, 2759 * where we cannot perform topology changes. Delegate the 2760 * work to the events thread. 2761 */ 2762 if (cp != NULL) 2763 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2764 } 2765 2766 static int 2767 swapongeom_locked(struct cdev *dev, struct vnode *vp) 2768 { 2769 struct g_provider *pp; 2770 struct g_consumer *cp; 2771 static struct g_geom *gp; 2772 struct swdevt *sp; 2773 u_long nblks; 2774 int error; 2775 2776 pp = g_dev_getprovider(dev); 2777 if (pp == NULL) 2778 return (ENODEV); 2779 mtx_lock(&sw_dev_mtx); 2780 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2781 cp = sp->sw_id; 2782 if (cp != NULL && cp->provider == pp) { 2783 mtx_unlock(&sw_dev_mtx); 2784 return (EBUSY); 2785 } 2786 } 2787 mtx_unlock(&sw_dev_mtx); 2788 if (gp == NULL) 2789 gp = g_new_geomf(&g_swap_class, "swap"); 2790 cp = g_new_consumer(gp); 2791 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2792 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2793 g_attach(cp, pp); 2794 /* 2795 * XXX: Every time you think you can improve the margin for 2796 * footshooting, somebody depends on the ability to do so: 2797 * savecore(8) wants to write to our swapdev so we cannot 2798 * set an exclusive count :-( 2799 */ 2800 error = g_access(cp, 1, 1, 0); 2801 if (error != 0) { 2802 g_detach(cp); 2803 g_destroy_consumer(cp); 2804 return (error); 2805 } 2806 nblks = pp->mediasize / DEV_BSIZE; 2807 swaponsomething(vp, cp, nblks, swapgeom_strategy, 2808 swapgeom_close, dev2udev(dev), 2809 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2810 return (0); 2811 } 2812 2813 static int 2814 swapongeom(struct vnode *vp) 2815 { 2816 int error; 2817 2818 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2819 if (vp->v_type != VCHR || (vp->v_iflag & VI_DOOMED) != 0) { 2820 error = ENOENT; 2821 } else { 2822 g_topology_lock(); 2823 error = swapongeom_locked(vp->v_rdev, vp); 2824 g_topology_unlock(); 2825 } 2826 VOP_UNLOCK(vp, 0); 2827 return (error); 2828 } 2829 2830 /* 2831 * VNODE backend 2832 * 2833 * This is used mainly for network filesystem (read: probably only tested 2834 * with NFS) swapfiles. 2835 * 2836 */ 2837 2838 static void 2839 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2840 { 2841 struct vnode *vp2; 2842 2843 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2844 2845 vp2 = sp->sw_id; 2846 vhold(vp2); 2847 if (bp->b_iocmd == BIO_WRITE) { 2848 if (bp->b_bufobj) 2849 bufobj_wdrop(bp->b_bufobj); 2850 bufobj_wref(&vp2->v_bufobj); 2851 } 2852 if (bp->b_bufobj != &vp2->v_bufobj) 2853 bp->b_bufobj = &vp2->v_bufobj; 2854 bp->b_vp = vp2; 2855 bp->b_iooffset = dbtob(bp->b_blkno); 2856 bstrategy(bp); 2857 return; 2858 } 2859 2860 static void 2861 swapdev_close(struct thread *td, struct swdevt *sp) 2862 { 2863 2864 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2865 vrele(sp->sw_vp); 2866 } 2867 2868 2869 static int 2870 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2871 { 2872 struct swdevt *sp; 2873 int error; 2874 2875 if (nblks == 0) 2876 return (ENXIO); 2877 mtx_lock(&sw_dev_mtx); 2878 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2879 if (sp->sw_id == vp) { 2880 mtx_unlock(&sw_dev_mtx); 2881 return (EBUSY); 2882 } 2883 } 2884 mtx_unlock(&sw_dev_mtx); 2885 2886 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2887 #ifdef MAC 2888 error = mac_system_check_swapon(td->td_ucred, vp); 2889 if (error == 0) 2890 #endif 2891 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 2892 (void) VOP_UNLOCK(vp, 0); 2893 if (error) 2894 return (error); 2895 2896 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 2897 NODEV, 0); 2898 return (0); 2899 } 2900 2901 static int 2902 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 2903 { 2904 int error, new, n; 2905 2906 new = nsw_wcount_async_max; 2907 error = sysctl_handle_int(oidp, &new, 0, req); 2908 if (error != 0 || req->newptr == NULL) 2909 return (error); 2910 2911 if (new > nswbuf / 2 || new < 1) 2912 return (EINVAL); 2913 2914 mtx_lock(&swbuf_mtx); 2915 while (nsw_wcount_async_max != new) { 2916 /* 2917 * Adjust difference. If the current async count is too low, 2918 * we will need to sqeeze our update slowly in. Sleep with a 2919 * higher priority than getpbuf() to finish faster. 2920 */ 2921 n = new - nsw_wcount_async_max; 2922 if (nsw_wcount_async + n >= 0) { 2923 nsw_wcount_async += n; 2924 nsw_wcount_async_max += n; 2925 wakeup(&nsw_wcount_async); 2926 } else { 2927 nsw_wcount_async_max -= nsw_wcount_async; 2928 nsw_wcount_async = 0; 2929 msleep(&nsw_wcount_async, &swbuf_mtx, PSWP, 2930 "swpsysctl", 0); 2931 } 2932 } 2933 mtx_unlock(&swbuf_mtx); 2934 2935 return (0); 2936 } 2937