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