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_compat.h" 75 #include "opt_swap.h" 76 #include "opt_vm.h" 77 78 #include <sys/param.h> 79 #include <sys/systm.h> 80 #include <sys/conf.h> 81 #include <sys/kernel.h> 82 #include <sys/priv.h> 83 #include <sys/proc.h> 84 #include <sys/bio.h> 85 #include <sys/buf.h> 86 #include <sys/disk.h> 87 #include <sys/fcntl.h> 88 #include <sys/mount.h> 89 #include <sys/namei.h> 90 #include <sys/vnode.h> 91 #include <sys/malloc.h> 92 #include <sys/pctrie.h> 93 #include <sys/racct.h> 94 #include <sys/resource.h> 95 #include <sys/resourcevar.h> 96 #include <sys/rwlock.h> 97 #include <sys/sbuf.h> 98 #include <sys/sysctl.h> 99 #include <sys/sysproto.h> 100 #include <sys/blist.h> 101 #include <sys/lock.h> 102 #include <sys/sx.h> 103 #include <sys/vmmeter.h> 104 105 #include <security/mac/mac_framework.h> 106 107 #include <vm/vm.h> 108 #include <vm/pmap.h> 109 #include <vm/vm_map.h> 110 #include <vm/vm_kern.h> 111 #include <vm/vm_object.h> 112 #include <vm/vm_page.h> 113 #include <vm/vm_pager.h> 114 #include <vm/vm_pageout.h> 115 #include <vm/vm_param.h> 116 #include <vm/swap_pager.h> 117 #include <vm/vm_extern.h> 118 #include <vm/uma.h> 119 120 #include <geom/geom.h> 121 122 /* 123 * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64. 124 * The 64-page limit is due to the radix code (kern/subr_blist.c). 125 */ 126 #ifndef MAX_PAGEOUT_CLUSTER 127 #define MAX_PAGEOUT_CLUSTER 32 128 #endif 129 130 #if !defined(SWB_NPAGES) 131 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER 132 #endif 133 134 #define SWAP_META_PAGES PCTRIE_COUNT 135 136 /* 137 * A swblk structure maps each page index within a 138 * SWAP_META_PAGES-aligned and sized range to the address of an 139 * on-disk swap block (or SWAPBLK_NONE). The collection of these 140 * mappings for an entire vm object is implemented as a pc-trie. 141 */ 142 struct swblk { 143 vm_pindex_t p; 144 daddr_t d[SWAP_META_PAGES]; 145 }; 146 147 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); 148 static struct mtx sw_dev_mtx; 149 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 150 static struct swdevt *swdevhd; /* Allocate from here next */ 151 static int nswapdev; /* Number of swap devices */ 152 int swap_pager_avail; 153 static struct sx swdev_syscall_lock; /* serialize swap(on|off) */ 154 155 static vm_ooffset_t swap_total; 156 SYSCTL_QUAD(_vm, OID_AUTO, swap_total, CTLFLAG_RD, &swap_total, 0, 157 "Total amount of available swap storage."); 158 static vm_ooffset_t swap_reserved; 159 SYSCTL_QUAD(_vm, OID_AUTO, swap_reserved, CTLFLAG_RD, &swap_reserved, 0, 160 "Amount of swap storage needed to back all allocated anonymous memory."); 161 static int overcommit = 0; 162 SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &overcommit, 0, 163 "Configure virtual memory overcommit behavior. See tuning(7) " 164 "for details."); 165 static unsigned long swzone; 166 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 167 "Actual size of swap metadata zone"); 168 static unsigned long swap_maxpages; 169 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, 170 "Maximum amount of swap supported"); 171 172 /* bits from overcommit */ 173 #define SWAP_RESERVE_FORCE_ON (1 << 0) 174 #define SWAP_RESERVE_RLIMIT_ON (1 << 1) 175 #define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2) 176 177 int 178 swap_reserve(vm_ooffset_t incr) 179 { 180 181 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 182 } 183 184 int 185 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 186 { 187 vm_ooffset_t r, s; 188 int res, error; 189 static int curfail; 190 static struct timeval lastfail; 191 struct uidinfo *uip; 192 193 uip = cred->cr_ruidinfo; 194 195 if (incr & PAGE_MASK) 196 panic("swap_reserve: & PAGE_MASK"); 197 198 #ifdef RACCT 199 if (racct_enable) { 200 PROC_LOCK(curproc); 201 error = racct_add(curproc, RACCT_SWAP, incr); 202 PROC_UNLOCK(curproc); 203 if (error != 0) 204 return (0); 205 } 206 #endif 207 208 res = 0; 209 mtx_lock(&sw_dev_mtx); 210 r = swap_reserved + incr; 211 if (overcommit & SWAP_RESERVE_ALLOW_NONWIRED) { 212 s = vm_cnt.v_page_count - vm_cnt.v_free_reserved - vm_cnt.v_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_FREE 0x02 /* free, period */ 315 #define SWM_POP 0x04 /* pop out */ 316 317 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 318 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 319 static int nsw_rcount; /* free read buffers */ 320 static int nsw_wcount_sync; /* limit write buffers / synchronous */ 321 static int nsw_wcount_async; /* limit write buffers / asynchronous */ 322 static int nsw_wcount_async_max;/* assigned maximum */ 323 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 324 325 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 326 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 327 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 328 "Maximum running async swap ops"); 329 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS); 330 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD | 331 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A", 332 "Swap Fragmentation Info"); 333 334 static struct sx sw_alloc_sx; 335 336 /* 337 * "named" and "unnamed" anon region objects. Try to reduce the overhead 338 * of searching a named list by hashing it just a little. 339 */ 340 341 #define NOBJLISTS 8 342 343 #define NOBJLIST(handle) \ 344 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 345 346 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 347 static uma_zone_t swblk_zone; 348 static uma_zone_t swpctrie_zone; 349 350 /* 351 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 352 * calls hooked from other parts of the VM system and do not appear here. 353 * (see vm/swap_pager.h). 354 */ 355 static vm_object_t 356 swap_pager_alloc(void *handle, vm_ooffset_t size, 357 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 358 static void swap_pager_dealloc(vm_object_t object); 359 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, 360 int *); 361 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, 362 int *, pgo_getpages_iodone_t, void *); 363 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 364 static boolean_t 365 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 366 static void swap_pager_init(void); 367 static void swap_pager_unswapped(vm_page_t); 368 static void swap_pager_swapoff(struct swdevt *sp); 369 370 struct pagerops swappagerops = { 371 .pgo_init = swap_pager_init, /* early system initialization of pager */ 372 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 373 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 374 .pgo_getpages = swap_pager_getpages, /* pagein */ 375 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 376 .pgo_putpages = swap_pager_putpages, /* pageout */ 377 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 378 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 379 }; 380 381 /* 382 * swap_*() routines are externally accessible. swp_*() routines are 383 * internal. 384 */ 385 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 386 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 387 388 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 389 "Maximum size of a swap block in pages"); 390 391 static void swp_sizecheck(void); 392 static void swp_pager_async_iodone(struct buf *bp); 393 static bool swp_pager_swblk_empty(struct swblk *sb, int start, int limit); 394 static int swapongeom(struct vnode *); 395 static int swaponvp(struct thread *, struct vnode *, u_long); 396 static int swapoff_one(struct swdevt *sp, struct ucred *cred); 397 398 /* 399 * Swap bitmap functions 400 */ 401 static void swp_pager_freeswapspace(daddr_t blk, daddr_t npages); 402 static daddr_t swp_pager_getswapspace(int npages); 403 404 /* 405 * Metadata functions 406 */ 407 static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 408 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 409 static void swp_pager_meta_free_all(vm_object_t); 410 static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 411 412 static void * 413 swblk_trie_alloc(struct pctrie *ptree) 414 { 415 416 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? 417 M_USE_RESERVE : 0))); 418 } 419 420 static void 421 swblk_trie_free(struct pctrie *ptree, void *node) 422 { 423 424 uma_zfree(swpctrie_zone, node); 425 } 426 427 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); 428 429 /* 430 * SWP_SIZECHECK() - update swap_pager_full indication 431 * 432 * update the swap_pager_almost_full indication and warn when we are 433 * about to run out of swap space, using lowat/hiwat hysteresis. 434 * 435 * Clear swap_pager_full ( task killing ) indication when lowat is met. 436 * 437 * No restrictions on call 438 * This routine may not block. 439 */ 440 static void 441 swp_sizecheck(void) 442 { 443 444 if (swap_pager_avail < nswap_lowat) { 445 if (swap_pager_almost_full == 0) { 446 printf("swap_pager: out of swap space\n"); 447 swap_pager_almost_full = 1; 448 } 449 } else { 450 swap_pager_full = 0; 451 if (swap_pager_avail > nswap_hiwat) 452 swap_pager_almost_full = 0; 453 } 454 } 455 456 /* 457 * SWAP_PAGER_INIT() - initialize the swap pager! 458 * 459 * Expected to be started from system init. NOTE: This code is run 460 * before much else so be careful what you depend on. Most of the VM 461 * system has yet to be initialized at this point. 462 */ 463 static void 464 swap_pager_init(void) 465 { 466 /* 467 * Initialize object lists 468 */ 469 int i; 470 471 for (i = 0; i < NOBJLISTS; ++i) 472 TAILQ_INIT(&swap_pager_object_list[i]); 473 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 474 sx_init(&sw_alloc_sx, "swspsx"); 475 sx_init(&swdev_syscall_lock, "swsysc"); 476 } 477 478 /* 479 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 480 * 481 * Expected to be started from pageout process once, prior to entering 482 * its main loop. 483 */ 484 void 485 swap_pager_swap_init(void) 486 { 487 unsigned long n, n2; 488 489 /* 490 * Number of in-transit swap bp operations. Don't 491 * exhaust the pbufs completely. Make sure we 492 * initialize workable values (0 will work for hysteresis 493 * but it isn't very efficient). 494 * 495 * The nsw_cluster_max is constrained by the bp->b_pages[] 496 * array (MAXPHYS/PAGE_SIZE) and our locally defined 497 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 498 * constrained by the swap device interleave stripe size. 499 * 500 * Currently we hardwire nsw_wcount_async to 4. This limit is 501 * designed to prevent other I/O from having high latencies due to 502 * our pageout I/O. The value 4 works well for one or two active swap 503 * devices but is probably a little low if you have more. Even so, 504 * a higher value would probably generate only a limited improvement 505 * with three or four active swap devices since the system does not 506 * typically have to pageout at extreme bandwidths. We will want 507 * at least 2 per swap devices, and 4 is a pretty good value if you 508 * have one NFS swap device due to the command/ack latency over NFS. 509 * So it all works out pretty well. 510 */ 511 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER); 512 513 mtx_lock(&pbuf_mtx); 514 nsw_rcount = (nswbuf + 1) / 2; 515 nsw_wcount_sync = (nswbuf + 3) / 4; 516 nsw_wcount_async = 4; 517 nsw_wcount_async_max = nsw_wcount_async; 518 mtx_unlock(&pbuf_mtx); 519 520 /* 521 * Initialize our zone, guessing on the number we need based 522 * on the number of pages in the system. 523 */ 524 n = vm_cnt.v_page_count / 2; 525 if (maxswzone && n > maxswzone / sizeof(struct swblk)) 526 n = maxswzone / sizeof(struct swblk); 527 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, 528 pctrie_zone_init, NULL, UMA_ALIGN_PTR, 529 UMA_ZONE_NOFREE | UMA_ZONE_VM); 530 if (swpctrie_zone == NULL) 531 panic("failed to create swap pctrie zone."); 532 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, 533 NULL, NULL, _Alignof(struct swblk) - 1, 534 UMA_ZONE_NOFREE | UMA_ZONE_VM); 535 if (swblk_zone == NULL) 536 panic("failed to create swap blk zone."); 537 n2 = n; 538 do { 539 if (uma_zone_reserve_kva(swblk_zone, n)) 540 break; 541 /* 542 * if the allocation failed, try a zone two thirds the 543 * size of the previous attempt. 544 */ 545 n -= ((n + 2) / 3); 546 } while (n > 0); 547 548 /* 549 * Often uma_zone_reserve_kva() cannot reserve exactly the 550 * requested size. Account for the difference when 551 * calculating swap_maxpages. 552 */ 553 n = uma_zone_get_max(swblk_zone); 554 555 if (n < n2) 556 printf("Swap blk zone entries reduced from %lu to %lu.\n", 557 n2, n); 558 swap_maxpages = n * SWAP_META_PAGES; 559 swzone = n * sizeof(struct swblk); 560 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 561 printf("Cannot reserve swap pctrie zone, " 562 "reduce kern.maxswzone.\n"); 563 } 564 565 static vm_object_t 566 swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size, 567 vm_ooffset_t offset) 568 { 569 vm_object_t object; 570 571 if (cred != NULL) { 572 if (!swap_reserve_by_cred(size, cred)) 573 return (NULL); 574 crhold(cred); 575 } 576 577 /* 578 * The un_pager.swp.swp_blks trie is initialized by 579 * vm_object_allocate() to ensure the correct order of 580 * visibility to other threads. 581 */ 582 object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset + 583 PAGE_MASK + size)); 584 585 object->handle = handle; 586 if (cred != NULL) { 587 object->cred = cred; 588 object->charge = size; 589 } 590 return (object); 591 } 592 593 /* 594 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 595 * its metadata structures. 596 * 597 * This routine is called from the mmap and fork code to create a new 598 * OBJT_SWAP object. 599 * 600 * This routine must ensure that no live duplicate is created for 601 * the named object request, which is protected against by 602 * holding the sw_alloc_sx lock in case handle != NULL. 603 */ 604 static vm_object_t 605 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 606 vm_ooffset_t offset, struct ucred *cred) 607 { 608 vm_object_t object; 609 610 if (handle != NULL) { 611 /* 612 * Reference existing named region or allocate new one. There 613 * should not be a race here against swp_pager_meta_build() 614 * as called from vm_page_remove() in regards to the lookup 615 * of the handle. 616 */ 617 sx_xlock(&sw_alloc_sx); 618 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 619 if (object == NULL) { 620 object = swap_pager_alloc_init(handle, cred, size, 621 offset); 622 if (object != NULL) { 623 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 624 object, pager_object_list); 625 } 626 } 627 sx_xunlock(&sw_alloc_sx); 628 } else { 629 object = swap_pager_alloc_init(handle, cred, size, offset); 630 } 631 return (object); 632 } 633 634 /* 635 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 636 * 637 * The swap backing for the object is destroyed. The code is 638 * designed such that we can reinstantiate it later, but this 639 * routine is typically called only when the entire object is 640 * about to be destroyed. 641 * 642 * The object must be locked. 643 */ 644 static void 645 swap_pager_dealloc(vm_object_t object) 646 { 647 648 VM_OBJECT_ASSERT_WLOCKED(object); 649 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 650 651 /* 652 * Remove from list right away so lookups will fail if we block for 653 * pageout completion. 654 */ 655 if (object->handle != NULL) { 656 VM_OBJECT_WUNLOCK(object); 657 sx_xlock(&sw_alloc_sx); 658 TAILQ_REMOVE(NOBJLIST(object->handle), object, 659 pager_object_list); 660 sx_xunlock(&sw_alloc_sx); 661 VM_OBJECT_WLOCK(object); 662 } 663 664 vm_object_pip_wait(object, "swpdea"); 665 666 /* 667 * Free all remaining metadata. We only bother to free it from 668 * the swap meta data. We do not attempt to free swapblk's still 669 * associated with vm_page_t's for this object. We do not care 670 * if paging is still in progress on some objects. 671 */ 672 swp_pager_meta_free_all(object); 673 object->handle = NULL; 674 object->type = OBJT_DEAD; 675 } 676 677 /************************************************************************ 678 * SWAP PAGER BITMAP ROUTINES * 679 ************************************************************************/ 680 681 /* 682 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 683 * 684 * Allocate swap for the requested number of pages. The starting 685 * swap block number (a page index) is returned or SWAPBLK_NONE 686 * if the allocation failed. 687 * 688 * Also has the side effect of advising that somebody made a mistake 689 * when they configured swap and didn't configure enough. 690 * 691 * This routine may not sleep. 692 * 693 * We allocate in round-robin fashion from the configured devices. 694 */ 695 static daddr_t 696 swp_pager_getswapspace(int npages) 697 { 698 daddr_t blk; 699 struct swdevt *sp; 700 int i; 701 702 blk = SWAPBLK_NONE; 703 mtx_lock(&sw_dev_mtx); 704 sp = swdevhd; 705 for (i = 0; i < nswapdev; i++) { 706 if (sp == NULL) 707 sp = TAILQ_FIRST(&swtailq); 708 if (!(sp->sw_flags & SW_CLOSING)) { 709 blk = blist_alloc(sp->sw_blist, npages); 710 if (blk != SWAPBLK_NONE) { 711 blk += sp->sw_first; 712 sp->sw_used += npages; 713 swap_pager_avail -= npages; 714 swp_sizecheck(); 715 swdevhd = TAILQ_NEXT(sp, sw_list); 716 goto done; 717 } 718 } 719 sp = TAILQ_NEXT(sp, sw_list); 720 } 721 if (swap_pager_full != 2) { 722 printf("swap_pager_getswapspace(%d): failed\n", npages); 723 swap_pager_full = 2; 724 swap_pager_almost_full = 1; 725 } 726 swdevhd = NULL; 727 done: 728 mtx_unlock(&sw_dev_mtx); 729 return (blk); 730 } 731 732 static int 733 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 734 { 735 736 return (blk >= sp->sw_first && blk < sp->sw_end); 737 } 738 739 static void 740 swp_pager_strategy(struct buf *bp) 741 { 742 struct swdevt *sp; 743 744 mtx_lock(&sw_dev_mtx); 745 TAILQ_FOREACH(sp, &swtailq, sw_list) { 746 if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) { 747 mtx_unlock(&sw_dev_mtx); 748 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 749 unmapped_buf_allowed) { 750 bp->b_data = unmapped_buf; 751 bp->b_offset = 0; 752 } else { 753 pmap_qenter((vm_offset_t)bp->b_data, 754 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 755 } 756 sp->sw_strategy(bp, sp); 757 return; 758 } 759 } 760 panic("Swapdev not found"); 761 } 762 763 764 /* 765 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 766 * 767 * This routine returns the specified swap blocks back to the bitmap. 768 * 769 * This routine may not sleep. 770 */ 771 static void 772 swp_pager_freeswapspace(daddr_t blk, daddr_t npages) 773 { 774 struct swdevt *sp; 775 776 if (npages == 0) 777 return; 778 mtx_lock(&sw_dev_mtx); 779 TAILQ_FOREACH(sp, &swtailq, sw_list) { 780 if (blk >= sp->sw_first && blk < sp->sw_end) { 781 sp->sw_used -= npages; 782 /* 783 * If we are attempting to stop swapping on 784 * this device, we don't want to mark any 785 * blocks free lest they be reused. 786 */ 787 if ((sp->sw_flags & SW_CLOSING) == 0) { 788 blist_free(sp->sw_blist, blk - sp->sw_first, 789 npages); 790 swap_pager_avail += npages; 791 swp_sizecheck(); 792 } 793 mtx_unlock(&sw_dev_mtx); 794 return; 795 } 796 } 797 panic("Swapdev not found"); 798 } 799 800 /* 801 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 802 */ 803 static int 804 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 805 { 806 struct sbuf sbuf; 807 struct swdevt *sp; 808 const char *devname; 809 int error; 810 811 error = sysctl_wire_old_buffer(req, 0); 812 if (error != 0) 813 return (error); 814 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 815 mtx_lock(&sw_dev_mtx); 816 TAILQ_FOREACH(sp, &swtailq, sw_list) { 817 if (vn_isdisk(sp->sw_vp, NULL)) 818 devname = devtoname(sp->sw_vp->v_rdev); 819 else 820 devname = "[file]"; 821 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 822 blist_stats(sp->sw_blist, &sbuf); 823 } 824 mtx_unlock(&sw_dev_mtx); 825 error = sbuf_finish(&sbuf); 826 sbuf_delete(&sbuf); 827 return (error); 828 } 829 830 /* 831 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 832 * range within an object. 833 * 834 * This is a globally accessible routine. 835 * 836 * This routine removes swapblk assignments from swap metadata. 837 * 838 * The external callers of this routine typically have already destroyed 839 * or renamed vm_page_t's associated with this range in the object so 840 * we should be ok. 841 * 842 * The object must be locked. 843 */ 844 void 845 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 846 { 847 848 swp_pager_meta_free(object, start, size); 849 } 850 851 /* 852 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 853 * 854 * Assigns swap blocks to the specified range within the object. The 855 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 856 * 857 * Returns 0 on success, -1 on failure. 858 */ 859 int 860 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 861 { 862 int n = 0; 863 daddr_t blk = SWAPBLK_NONE; 864 vm_pindex_t beg = start; /* save start index */ 865 866 VM_OBJECT_WLOCK(object); 867 while (size) { 868 if (n == 0) { 869 n = BLIST_MAX_ALLOC; 870 while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) { 871 n >>= 1; 872 if (n == 0) { 873 swp_pager_meta_free(object, beg, start - beg); 874 VM_OBJECT_WUNLOCK(object); 875 return (-1); 876 } 877 } 878 } 879 swp_pager_meta_build(object, start, blk); 880 --size; 881 ++start; 882 ++blk; 883 --n; 884 } 885 swp_pager_meta_free(object, start, n); 886 VM_OBJECT_WUNLOCK(object); 887 return (0); 888 } 889 890 /* 891 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 892 * and destroy the source. 893 * 894 * Copy any valid swapblks from the source to the destination. In 895 * cases where both the source and destination have a valid swapblk, 896 * we keep the destination's. 897 * 898 * This routine is allowed to sleep. It may sleep allocating metadata 899 * indirectly through swp_pager_meta_build() or if paging is still in 900 * progress on the source. 901 * 902 * The source object contains no vm_page_t's (which is just as well) 903 * 904 * The source object is of type OBJT_SWAP. 905 * 906 * The source and destination objects must be locked. 907 * Both object locks may temporarily be released. 908 */ 909 void 910 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 911 vm_pindex_t offset, int destroysource) 912 { 913 vm_pindex_t i; 914 915 VM_OBJECT_ASSERT_WLOCKED(srcobject); 916 VM_OBJECT_ASSERT_WLOCKED(dstobject); 917 918 /* 919 * If destroysource is set, we remove the source object from the 920 * swap_pager internal queue now. 921 */ 922 if (destroysource && srcobject->handle != NULL) { 923 vm_object_pip_add(srcobject, 1); 924 VM_OBJECT_WUNLOCK(srcobject); 925 vm_object_pip_add(dstobject, 1); 926 VM_OBJECT_WUNLOCK(dstobject); 927 sx_xlock(&sw_alloc_sx); 928 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 929 pager_object_list); 930 sx_xunlock(&sw_alloc_sx); 931 VM_OBJECT_WLOCK(dstobject); 932 vm_object_pip_wakeup(dstobject); 933 VM_OBJECT_WLOCK(srcobject); 934 vm_object_pip_wakeup(srcobject); 935 } 936 937 /* 938 * transfer source to destination. 939 */ 940 for (i = 0; i < dstobject->size; ++i) { 941 daddr_t dstaddr; 942 943 /* 944 * Locate (without changing) the swapblk on the destination, 945 * unless it is invalid in which case free it silently, or 946 * if the destination is a resident page, in which case the 947 * source is thrown away. 948 */ 949 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 950 951 if (dstaddr == SWAPBLK_NONE) { 952 /* 953 * Destination has no swapblk and is not resident, 954 * copy source. 955 */ 956 daddr_t srcaddr; 957 958 srcaddr = swp_pager_meta_ctl( 959 srcobject, 960 i + offset, 961 SWM_POP 962 ); 963 964 if (srcaddr != SWAPBLK_NONE) { 965 /* 966 * swp_pager_meta_build() can sleep. 967 */ 968 vm_object_pip_add(srcobject, 1); 969 VM_OBJECT_WUNLOCK(srcobject); 970 vm_object_pip_add(dstobject, 1); 971 swp_pager_meta_build(dstobject, i, srcaddr); 972 vm_object_pip_wakeup(dstobject); 973 VM_OBJECT_WLOCK(srcobject); 974 vm_object_pip_wakeup(srcobject); 975 } 976 } else { 977 /* 978 * Destination has valid swapblk or it is represented 979 * by a resident page. We destroy the sourceblock. 980 */ 981 982 swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE); 983 } 984 } 985 986 /* 987 * Free left over swap blocks in source. 988 * 989 * We have to revert the type to OBJT_DEFAULT so we do not accidentally 990 * double-remove the object from the swap queues. 991 */ 992 if (destroysource) { 993 swp_pager_meta_free_all(srcobject); 994 /* 995 * Reverting the type is not necessary, the caller is going 996 * to destroy srcobject directly, but I'm doing it here 997 * for consistency since we've removed the object from its 998 * queues. 999 */ 1000 srcobject->type = OBJT_DEFAULT; 1001 } 1002 } 1003 1004 /* 1005 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1006 * the requested page. 1007 * 1008 * We determine whether good backing store exists for the requested 1009 * page and return TRUE if it does, FALSE if it doesn't. 1010 * 1011 * If TRUE, we also try to determine how much valid, contiguous backing 1012 * store exists before and after the requested page. 1013 */ 1014 static boolean_t 1015 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1016 int *after) 1017 { 1018 daddr_t blk, blk0; 1019 int i; 1020 1021 VM_OBJECT_ASSERT_LOCKED(object); 1022 1023 /* 1024 * do we have good backing store at the requested index ? 1025 */ 1026 blk0 = swp_pager_meta_ctl(object, pindex, 0); 1027 if (blk0 == SWAPBLK_NONE) { 1028 if (before) 1029 *before = 0; 1030 if (after) 1031 *after = 0; 1032 return (FALSE); 1033 } 1034 1035 /* 1036 * find backwards-looking contiguous good backing store 1037 */ 1038 if (before != NULL) { 1039 for (i = 1; i < SWB_NPAGES; i++) { 1040 if (i > pindex) 1041 break; 1042 blk = swp_pager_meta_ctl(object, pindex - i, 0); 1043 if (blk != blk0 - i) 1044 break; 1045 } 1046 *before = i - 1; 1047 } 1048 1049 /* 1050 * find forward-looking contiguous good backing store 1051 */ 1052 if (after != NULL) { 1053 for (i = 1; i < SWB_NPAGES; i++) { 1054 blk = swp_pager_meta_ctl(object, pindex + i, 0); 1055 if (blk != blk0 + i) 1056 break; 1057 } 1058 *after = i - 1; 1059 } 1060 return (TRUE); 1061 } 1062 1063 /* 1064 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1065 * 1066 * This removes any associated swap backing store, whether valid or 1067 * not, from the page. 1068 * 1069 * This routine is typically called when a page is made dirty, at 1070 * which point any associated swap can be freed. MADV_FREE also 1071 * calls us in a special-case situation 1072 * 1073 * NOTE!!! If the page is clean and the swap was valid, the caller 1074 * should make the page dirty before calling this routine. This routine 1075 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1076 * depends on it. 1077 * 1078 * This routine may not sleep. 1079 * 1080 * The object containing the page must be locked. 1081 */ 1082 static void 1083 swap_pager_unswapped(vm_page_t m) 1084 { 1085 1086 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); 1087 } 1088 1089 /* 1090 * swap_pager_getpages() - bring pages in from swap 1091 * 1092 * Attempt to page in the pages in array "m" of length "count". The caller 1093 * may optionally specify that additional pages preceding and succeeding 1094 * the specified range be paged in. The number of such pages is returned 1095 * in the "rbehind" and "rahead" parameters, and they will be in the 1096 * inactive queue upon return. 1097 * 1098 * The pages in "m" must be busied and will remain busied upon return. 1099 */ 1100 static int 1101 swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind, 1102 int *rahead) 1103 { 1104 struct buf *bp; 1105 vm_page_t mpred, msucc, p; 1106 vm_pindex_t pindex; 1107 daddr_t blk; 1108 int i, j, maxahead, maxbehind, reqcount, shift; 1109 1110 reqcount = count; 1111 1112 VM_OBJECT_WUNLOCK(object); 1113 bp = getpbuf(&nsw_rcount); 1114 VM_OBJECT_WLOCK(object); 1115 1116 if (!swap_pager_haspage(object, m[0]->pindex, &maxbehind, &maxahead)) { 1117 relpbuf(bp, &nsw_rcount); 1118 return (VM_PAGER_FAIL); 1119 } 1120 1121 /* 1122 * Clip the readahead and readbehind ranges to exclude resident pages. 1123 */ 1124 if (rahead != NULL) { 1125 KASSERT(reqcount - 1 <= maxahead, 1126 ("page count %d extends beyond swap block", reqcount)); 1127 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1128 pindex = m[reqcount - 1]->pindex; 1129 msucc = TAILQ_NEXT(m[reqcount - 1], listq); 1130 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1131 *rahead = msucc->pindex - pindex - 1; 1132 } 1133 if (rbehind != NULL) { 1134 *rbehind = imin(*rbehind, maxbehind); 1135 pindex = m[0]->pindex; 1136 mpred = TAILQ_PREV(m[0], pglist, listq); 1137 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1138 *rbehind = pindex - mpred->pindex - 1; 1139 } 1140 1141 /* 1142 * Allocate readahead and readbehind pages. 1143 */ 1144 shift = rbehind != NULL ? *rbehind : 0; 1145 if (shift != 0) { 1146 for (i = 1; i <= shift; i++) { 1147 p = vm_page_alloc(object, m[0]->pindex - i, 1148 VM_ALLOC_NORMAL); 1149 if (p == NULL) { 1150 /* Shift allocated pages to the left. */ 1151 for (j = 0; j < i - 1; j++) 1152 bp->b_pages[j] = 1153 bp->b_pages[j + shift - i + 1]; 1154 break; 1155 } 1156 bp->b_pages[shift - i] = p; 1157 } 1158 shift = i - 1; 1159 *rbehind = shift; 1160 } 1161 for (i = 0; i < reqcount; i++) 1162 bp->b_pages[i + shift] = m[i]; 1163 if (rahead != NULL) { 1164 for (i = 0; i < *rahead; i++) { 1165 p = vm_page_alloc(object, 1166 m[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1167 if (p == NULL) 1168 break; 1169 bp->b_pages[shift + reqcount + i] = p; 1170 } 1171 *rahead = i; 1172 } 1173 if (rbehind != NULL) 1174 count += *rbehind; 1175 if (rahead != NULL) 1176 count += *rahead; 1177 1178 vm_object_pip_add(object, count); 1179 1180 for (i = 0; i < count; i++) 1181 bp->b_pages[i]->oflags |= VPO_SWAPINPROG; 1182 1183 pindex = bp->b_pages[0]->pindex; 1184 blk = swp_pager_meta_ctl(object, pindex, 0); 1185 KASSERT(blk != SWAPBLK_NONE, 1186 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1187 1188 VM_OBJECT_WUNLOCK(object); 1189 1190 bp->b_flags |= B_PAGING; 1191 bp->b_iocmd = BIO_READ; 1192 bp->b_iodone = swp_pager_async_iodone; 1193 bp->b_rcred = crhold(thread0.td_ucred); 1194 bp->b_wcred = crhold(thread0.td_ucred); 1195 bp->b_blkno = blk; 1196 bp->b_bcount = PAGE_SIZE * count; 1197 bp->b_bufsize = PAGE_SIZE * count; 1198 bp->b_npages = count; 1199 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1200 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1201 1202 VM_CNT_INC(v_swapin); 1203 VM_CNT_ADD(v_swappgsin, count); 1204 1205 /* 1206 * perform the I/O. NOTE!!! bp cannot be considered valid after 1207 * this point because we automatically release it on completion. 1208 * Instead, we look at the one page we are interested in which we 1209 * still hold a lock on even through the I/O completion. 1210 * 1211 * The other pages in our m[] array are also released on completion, 1212 * so we cannot assume they are valid anymore either. 1213 * 1214 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1215 */ 1216 BUF_KERNPROC(bp); 1217 swp_pager_strategy(bp); 1218 1219 /* 1220 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1221 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1222 * is set in the metadata for each page in the request. 1223 */ 1224 VM_OBJECT_WLOCK(object); 1225 while ((m[0]->oflags & VPO_SWAPINPROG) != 0) { 1226 m[0]->oflags |= VPO_SWAPSLEEP; 1227 VM_CNT_INC(v_intrans); 1228 if (VM_OBJECT_SLEEP(object, &object->paging_in_progress, PSWP, 1229 "swread", hz * 20)) { 1230 printf( 1231 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1232 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1233 } 1234 } 1235 1236 /* 1237 * If we had an unrecoverable read error pages will not be valid. 1238 */ 1239 for (i = 0; i < reqcount; i++) 1240 if (m[i]->valid != VM_PAGE_BITS_ALL) 1241 return (VM_PAGER_ERROR); 1242 1243 return (VM_PAGER_OK); 1244 1245 /* 1246 * A final note: in a low swap situation, we cannot deallocate swap 1247 * and mark a page dirty here because the caller is likely to mark 1248 * the page clean when we return, causing the page to possibly revert 1249 * to all-zero's later. 1250 */ 1251 } 1252 1253 /* 1254 * swap_pager_getpages_async(): 1255 * 1256 * Right now this is emulation of asynchronous operation on top of 1257 * swap_pager_getpages(). 1258 */ 1259 static int 1260 swap_pager_getpages_async(vm_object_t object, vm_page_t *m, int count, 1261 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1262 { 1263 int r, error; 1264 1265 r = swap_pager_getpages(object, m, count, rbehind, rahead); 1266 VM_OBJECT_WUNLOCK(object); 1267 switch (r) { 1268 case VM_PAGER_OK: 1269 error = 0; 1270 break; 1271 case VM_PAGER_ERROR: 1272 error = EIO; 1273 break; 1274 case VM_PAGER_FAIL: 1275 error = EINVAL; 1276 break; 1277 default: 1278 panic("unhandled swap_pager_getpages() error %d", r); 1279 } 1280 (iodone)(arg, m, count, error); 1281 VM_OBJECT_WLOCK(object); 1282 1283 return (r); 1284 } 1285 1286 /* 1287 * swap_pager_putpages: 1288 * 1289 * Assign swap (if necessary) and initiate I/O on the specified pages. 1290 * 1291 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1292 * are automatically converted to SWAP objects. 1293 * 1294 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1295 * vm_page reservation system coupled with properly written VFS devices 1296 * should ensure that no low-memory deadlock occurs. This is an area 1297 * which needs work. 1298 * 1299 * The parent has N vm_object_pip_add() references prior to 1300 * calling us and will remove references for rtvals[] that are 1301 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1302 * completion. 1303 * 1304 * The parent has soft-busy'd the pages it passes us and will unbusy 1305 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1306 * We need to unbusy the rest on I/O completion. 1307 */ 1308 static void 1309 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1310 int flags, int *rtvals) 1311 { 1312 int i, n; 1313 boolean_t sync; 1314 1315 if (count && m[0]->object != object) { 1316 panic("swap_pager_putpages: object mismatch %p/%p", 1317 object, 1318 m[0]->object 1319 ); 1320 } 1321 1322 /* 1323 * Step 1 1324 * 1325 * Turn object into OBJT_SWAP 1326 * check for bogus sysops 1327 * force sync if not pageout process 1328 */ 1329 if (object->type != OBJT_SWAP) 1330 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1331 VM_OBJECT_WUNLOCK(object); 1332 1333 n = 0; 1334 if (curproc != pageproc) 1335 sync = TRUE; 1336 else 1337 sync = (flags & VM_PAGER_PUT_SYNC) != 0; 1338 1339 /* 1340 * Step 2 1341 * 1342 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1343 * The page is left dirty until the pageout operation completes 1344 * successfully. 1345 */ 1346 for (i = 0; i < count; i += n) { 1347 int j; 1348 struct buf *bp; 1349 daddr_t blk; 1350 1351 /* 1352 * Maximum I/O size is limited by a number of factors. 1353 */ 1354 n = min(BLIST_MAX_ALLOC, count - i); 1355 n = min(n, nsw_cluster_max); 1356 1357 /* 1358 * Get biggest block of swap we can. If we fail, fall 1359 * back and try to allocate a smaller block. Don't go 1360 * overboard trying to allocate space if it would overly 1361 * fragment swap. 1362 */ 1363 while ( 1364 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE && 1365 n > 4 1366 ) { 1367 n >>= 1; 1368 } 1369 if (blk == SWAPBLK_NONE) { 1370 for (j = 0; j < n; ++j) 1371 rtvals[i+j] = VM_PAGER_FAIL; 1372 continue; 1373 } 1374 1375 /* 1376 * All I/O parameters have been satisfied, build the I/O 1377 * request and assign the swap space. 1378 */ 1379 if (sync == TRUE) { 1380 bp = getpbuf(&nsw_wcount_sync); 1381 } else { 1382 bp = getpbuf(&nsw_wcount_async); 1383 bp->b_flags = B_ASYNC; 1384 } 1385 bp->b_flags |= B_PAGING; 1386 bp->b_iocmd = BIO_WRITE; 1387 1388 bp->b_rcred = crhold(thread0.td_ucred); 1389 bp->b_wcred = crhold(thread0.td_ucred); 1390 bp->b_bcount = PAGE_SIZE * n; 1391 bp->b_bufsize = PAGE_SIZE * n; 1392 bp->b_blkno = blk; 1393 1394 VM_OBJECT_WLOCK(object); 1395 for (j = 0; j < n; ++j) { 1396 vm_page_t mreq = m[i+j]; 1397 1398 swp_pager_meta_build( 1399 mreq->object, 1400 mreq->pindex, 1401 blk + j 1402 ); 1403 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1404 mreq->oflags |= VPO_SWAPINPROG; 1405 bp->b_pages[j] = mreq; 1406 } 1407 VM_OBJECT_WUNLOCK(object); 1408 bp->b_npages = n; 1409 /* 1410 * Must set dirty range for NFS to work. 1411 */ 1412 bp->b_dirtyoff = 0; 1413 bp->b_dirtyend = bp->b_bcount; 1414 1415 VM_CNT_INC(v_swapout); 1416 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1417 1418 /* 1419 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1420 * can call the async completion routine at the end of a 1421 * synchronous I/O operation. Otherwise, our caller would 1422 * perform duplicate unbusy and wakeup operations on the page 1423 * and object, respectively. 1424 */ 1425 for (j = 0; j < n; j++) 1426 rtvals[i + j] = VM_PAGER_PEND; 1427 1428 /* 1429 * asynchronous 1430 * 1431 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1432 */ 1433 if (sync == FALSE) { 1434 bp->b_iodone = swp_pager_async_iodone; 1435 BUF_KERNPROC(bp); 1436 swp_pager_strategy(bp); 1437 continue; 1438 } 1439 1440 /* 1441 * synchronous 1442 * 1443 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1444 */ 1445 bp->b_iodone = bdone; 1446 swp_pager_strategy(bp); 1447 1448 /* 1449 * Wait for the sync I/O to complete. 1450 */ 1451 bwait(bp, PVM, "swwrt"); 1452 1453 /* 1454 * Now that we are through with the bp, we can call the 1455 * normal async completion, which frees everything up. 1456 */ 1457 swp_pager_async_iodone(bp); 1458 } 1459 VM_OBJECT_WLOCK(object); 1460 } 1461 1462 /* 1463 * swp_pager_async_iodone: 1464 * 1465 * Completion routine for asynchronous reads and writes from/to swap. 1466 * Also called manually by synchronous code to finish up a bp. 1467 * 1468 * This routine may not sleep. 1469 */ 1470 static void 1471 swp_pager_async_iodone(struct buf *bp) 1472 { 1473 int i; 1474 vm_object_t object = NULL; 1475 1476 /* 1477 * report error 1478 */ 1479 if (bp->b_ioflags & BIO_ERROR) { 1480 printf( 1481 "swap_pager: I/O error - %s failed; blkno %ld," 1482 "size %ld, error %d\n", 1483 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1484 (long)bp->b_blkno, 1485 (long)bp->b_bcount, 1486 bp->b_error 1487 ); 1488 } 1489 1490 /* 1491 * remove the mapping for kernel virtual 1492 */ 1493 if (buf_mapped(bp)) 1494 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1495 else 1496 bp->b_data = bp->b_kvabase; 1497 1498 if (bp->b_npages) { 1499 object = bp->b_pages[0]->object; 1500 VM_OBJECT_WLOCK(object); 1501 } 1502 1503 /* 1504 * cleanup pages. If an error occurs writing to swap, we are in 1505 * very serious trouble. If it happens to be a disk error, though, 1506 * we may be able to recover by reassigning the swap later on. So 1507 * in this case we remove the m->swapblk assignment for the page 1508 * but do not free it in the rlist. The errornous block(s) are thus 1509 * never reallocated as swap. Redirty the page and continue. 1510 */ 1511 for (i = 0; i < bp->b_npages; ++i) { 1512 vm_page_t m = bp->b_pages[i]; 1513 1514 m->oflags &= ~VPO_SWAPINPROG; 1515 if (m->oflags & VPO_SWAPSLEEP) { 1516 m->oflags &= ~VPO_SWAPSLEEP; 1517 wakeup(&object->paging_in_progress); 1518 } 1519 1520 if (bp->b_ioflags & BIO_ERROR) { 1521 /* 1522 * If an error occurs I'd love to throw the swapblk 1523 * away without freeing it back to swapspace, so it 1524 * can never be used again. But I can't from an 1525 * interrupt. 1526 */ 1527 if (bp->b_iocmd == BIO_READ) { 1528 /* 1529 * NOTE: for reads, m->dirty will probably 1530 * be overridden by the original caller of 1531 * getpages so don't play cute tricks here. 1532 */ 1533 m->valid = 0; 1534 } else { 1535 /* 1536 * If a write error occurs, reactivate page 1537 * so it doesn't clog the inactive list, 1538 * then finish the I/O. 1539 */ 1540 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1541 vm_page_lock(m); 1542 vm_page_activate(m); 1543 vm_page_unlock(m); 1544 vm_page_sunbusy(m); 1545 } 1546 } else if (bp->b_iocmd == BIO_READ) { 1547 /* 1548 * NOTE: for reads, m->dirty will probably be 1549 * overridden by the original caller of getpages so 1550 * we cannot set them in order to free the underlying 1551 * swap in a low-swap situation. I don't think we'd 1552 * want to do that anyway, but it was an optimization 1553 * that existed in the old swapper for a time before 1554 * it got ripped out due to precisely this problem. 1555 */ 1556 KASSERT(!pmap_page_is_mapped(m), 1557 ("swp_pager_async_iodone: page %p is mapped", m)); 1558 KASSERT(m->dirty == 0, 1559 ("swp_pager_async_iodone: page %p is dirty", m)); 1560 1561 m->valid = VM_PAGE_BITS_ALL; 1562 if (i < bp->b_pgbefore || 1563 i >= bp->b_npages - bp->b_pgafter) 1564 vm_page_readahead_finish(m); 1565 } else { 1566 /* 1567 * For write success, clear the dirty 1568 * status, then finish the I/O ( which decrements the 1569 * busy count and possibly wakes waiter's up ). 1570 * A page is only written to swap after a period of 1571 * inactivity. Therefore, we do not expect it to be 1572 * reused. 1573 */ 1574 KASSERT(!pmap_page_is_write_mapped(m), 1575 ("swp_pager_async_iodone: page %p is not write" 1576 " protected", m)); 1577 vm_page_undirty(m); 1578 vm_page_lock(m); 1579 vm_page_deactivate_noreuse(m); 1580 vm_page_unlock(m); 1581 vm_page_sunbusy(m); 1582 } 1583 } 1584 1585 /* 1586 * adjust pip. NOTE: the original parent may still have its own 1587 * pip refs on the object. 1588 */ 1589 if (object != NULL) { 1590 vm_object_pip_wakeupn(object, bp->b_npages); 1591 VM_OBJECT_WUNLOCK(object); 1592 } 1593 1594 /* 1595 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1596 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1597 * trigger a KASSERT in relpbuf(). 1598 */ 1599 if (bp->b_vp) { 1600 bp->b_vp = NULL; 1601 bp->b_bufobj = NULL; 1602 } 1603 /* 1604 * release the physical I/O buffer 1605 */ 1606 relpbuf( 1607 bp, 1608 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount : 1609 ((bp->b_flags & B_ASYNC) ? 1610 &nsw_wcount_async : 1611 &nsw_wcount_sync 1612 ) 1613 ) 1614 ); 1615 } 1616 1617 int 1618 swap_pager_nswapdev(void) 1619 { 1620 1621 return (nswapdev); 1622 } 1623 1624 /* 1625 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in 1626 * 1627 * This routine dissociates the page at the given index within an object 1628 * from its backing store, paging it in if it does not reside in memory. 1629 * If the page is paged in, it is marked dirty and placed in the laundry 1630 * queue. The page is marked dirty because it no longer has backing 1631 * store. It is placed in the laundry queue because it has not been 1632 * accessed recently. Otherwise, it would already reside in memory. 1633 * 1634 * We also attempt to swap in all other pages in the swap block. 1635 * However, we only guarantee that the one at the specified index is 1636 * paged in. 1637 * 1638 * XXX - The code to page the whole block in doesn't work, so we 1639 * revert to the one-by-one behavior for now. Sigh. 1640 */ 1641 static inline void 1642 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex) 1643 { 1644 vm_page_t m; 1645 1646 vm_object_pip_add(object, 1); 1647 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL); 1648 if (m->valid == VM_PAGE_BITS_ALL) { 1649 vm_object_pip_wakeup(object); 1650 vm_page_dirty(m); 1651 #ifdef INVARIANTS 1652 vm_page_lock(m); 1653 if (m->wire_count == 0 && m->queue == PQ_NONE) 1654 panic("page %p is neither wired nor queued", m); 1655 vm_page_unlock(m); 1656 #endif 1657 vm_page_xunbusy(m); 1658 vm_pager_page_unswapped(m); 1659 return; 1660 } 1661 1662 if (swap_pager_getpages(object, &m, 1, NULL, NULL) != VM_PAGER_OK) 1663 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/ 1664 vm_object_pip_wakeup(object); 1665 vm_page_dirty(m); 1666 vm_page_lock(m); 1667 vm_page_launder(m); 1668 vm_page_unlock(m); 1669 vm_page_xunbusy(m); 1670 vm_pager_page_unswapped(m); 1671 } 1672 1673 /* 1674 * swap_pager_swapoff: 1675 * 1676 * Page in all of the pages that have been paged out to the 1677 * given device. The corresponding blocks in the bitmap must be 1678 * marked as allocated and the device must be flagged SW_CLOSING. 1679 * There may be no processes swapped out to the device. 1680 * 1681 * This routine may block. 1682 */ 1683 static void 1684 swap_pager_swapoff(struct swdevt *sp) 1685 { 1686 struct swblk *sb; 1687 vm_object_t object; 1688 vm_pindex_t pi; 1689 int i, retries; 1690 1691 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 1692 1693 retries = 0; 1694 full_rescan: 1695 mtx_lock(&vm_object_list_mtx); 1696 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1697 if (object->type != OBJT_SWAP) 1698 continue; 1699 mtx_unlock(&vm_object_list_mtx); 1700 /* Depends on type-stability. */ 1701 VM_OBJECT_WLOCK(object); 1702 1703 /* 1704 * Dead objects are eventually terminated on their own. 1705 */ 1706 if ((object->flags & OBJ_DEAD) != 0) 1707 goto next_obj; 1708 1709 /* 1710 * Sync with fences placed after pctrie 1711 * initialization. We must not access pctrie below 1712 * unless we checked that our object is swap and not 1713 * dead. 1714 */ 1715 atomic_thread_fence_acq(); 1716 if (object->type != OBJT_SWAP) 1717 goto next_obj; 1718 1719 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1720 &object->un_pager.swp.swp_blks, pi)) != NULL; ) { 1721 pi = sb->p + SWAP_META_PAGES; 1722 for (i = 0; i < SWAP_META_PAGES; i++) { 1723 if (sb->d[i] == SWAPBLK_NONE) 1724 continue; 1725 if (swp_pager_isondev(sb->d[i], sp)) 1726 swp_pager_force_pagein(object, 1727 sb->p + i); 1728 } 1729 } 1730 next_obj: 1731 VM_OBJECT_WUNLOCK(object); 1732 mtx_lock(&vm_object_list_mtx); 1733 } 1734 mtx_unlock(&vm_object_list_mtx); 1735 1736 if (sp->sw_used) { 1737 /* 1738 * Objects may be locked or paging to the device being 1739 * removed, so we will miss their pages and need to 1740 * make another pass. We have marked this device as 1741 * SW_CLOSING, so the activity should finish soon. 1742 */ 1743 retries++; 1744 if (retries > 100) { 1745 panic("swapoff: failed to locate %d swap blocks", 1746 sp->sw_used); 1747 } 1748 pause("swpoff", hz / 20); 1749 goto full_rescan; 1750 } 1751 EVENTHANDLER_INVOKE(swapoff, sp); 1752 } 1753 1754 /************************************************************************ 1755 * SWAP META DATA * 1756 ************************************************************************ 1757 * 1758 * These routines manipulate the swap metadata stored in the 1759 * OBJT_SWAP object. 1760 * 1761 * Swap metadata is implemented with a global hash and not directly 1762 * linked into the object. Instead the object simply contains 1763 * appropriate tracking counters. 1764 */ 1765 1766 /* 1767 * SWP_PAGER_SWBLK_EMPTY() - is a range of blocks free? 1768 */ 1769 static bool 1770 swp_pager_swblk_empty(struct swblk *sb, int start, int limit) 1771 { 1772 int i; 1773 1774 MPASS(0 <= start && start <= limit && limit <= SWAP_META_PAGES); 1775 for (i = start; i < limit; i++) { 1776 if (sb->d[i] != SWAPBLK_NONE) 1777 return (false); 1778 } 1779 return (true); 1780 } 1781 1782 /* 1783 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1784 * 1785 * We first convert the object to a swap object if it is a default 1786 * object. 1787 * 1788 * The specified swapblk is added to the object's swap metadata. If 1789 * the swapblk is not valid, it is freed instead. Any previously 1790 * assigned swapblk is freed. 1791 */ 1792 static void 1793 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1794 { 1795 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 1796 struct swblk *sb, *sb1; 1797 vm_pindex_t modpi, rdpi; 1798 int error, i; 1799 1800 VM_OBJECT_ASSERT_WLOCKED(object); 1801 1802 /* 1803 * Convert default object to swap object if necessary 1804 */ 1805 if (object->type != OBJT_SWAP) { 1806 pctrie_init(&object->un_pager.swp.swp_blks); 1807 1808 /* 1809 * Ensure that swap_pager_swapoff()'s iteration over 1810 * object_list does not see a garbage pctrie. 1811 */ 1812 atomic_thread_fence_rel(); 1813 1814 object->type = OBJT_SWAP; 1815 KASSERT(object->handle == NULL, ("default pager with handle")); 1816 } 1817 1818 rdpi = rounddown(pindex, SWAP_META_PAGES); 1819 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi); 1820 if (sb == NULL) { 1821 if (swapblk == SWAPBLK_NONE) 1822 return; 1823 for (;;) { 1824 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 1825 pageproc ? M_USE_RESERVE : 0)); 1826 if (sb != NULL) { 1827 sb->p = rdpi; 1828 for (i = 0; i < SWAP_META_PAGES; i++) 1829 sb->d[i] = SWAPBLK_NONE; 1830 if (atomic_cmpset_int(&swblk_zone_exhausted, 1831 1, 0)) 1832 printf("swblk zone ok\n"); 1833 break; 1834 } 1835 VM_OBJECT_WUNLOCK(object); 1836 if (uma_zone_exhausted(swblk_zone)) { 1837 if (atomic_cmpset_int(&swblk_zone_exhausted, 1838 0, 1)) 1839 printf("swap blk zone exhausted, " 1840 "increase kern.maxswzone\n"); 1841 vm_pageout_oom(VM_OOM_SWAPZ); 1842 pause("swzonxb", 10); 1843 } else 1844 uma_zwait(swblk_zone); 1845 VM_OBJECT_WLOCK(object); 1846 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 1847 rdpi); 1848 if (sb != NULL) 1849 /* 1850 * Somebody swapped out a nearby page, 1851 * allocating swblk at the rdpi index, 1852 * while we dropped the object lock. 1853 */ 1854 goto allocated; 1855 } 1856 for (;;) { 1857 error = SWAP_PCTRIE_INSERT( 1858 &object->un_pager.swp.swp_blks, sb); 1859 if (error == 0) { 1860 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1861 1, 0)) 1862 printf("swpctrie zone ok\n"); 1863 break; 1864 } 1865 VM_OBJECT_WUNLOCK(object); 1866 if (uma_zone_exhausted(swpctrie_zone)) { 1867 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1868 0, 1)) 1869 printf("swap pctrie zone exhausted, " 1870 "increase kern.maxswzone\n"); 1871 vm_pageout_oom(VM_OOM_SWAPZ); 1872 pause("swzonxp", 10); 1873 } else 1874 uma_zwait(swpctrie_zone); 1875 VM_OBJECT_WLOCK(object); 1876 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 1877 rdpi); 1878 if (sb1 != NULL) { 1879 uma_zfree(swblk_zone, sb); 1880 sb = sb1; 1881 goto allocated; 1882 } 1883 } 1884 } 1885 allocated: 1886 MPASS(sb->p == rdpi); 1887 1888 modpi = pindex % SWAP_META_PAGES; 1889 /* Delete prior contents of metadata. */ 1890 if (sb->d[modpi] != SWAPBLK_NONE) 1891 swp_pager_freeswapspace(sb->d[modpi], 1); 1892 /* Enter block into metadata. */ 1893 sb->d[modpi] = swapblk; 1894 1895 /* 1896 * Free the swblk if we end up with the empty page run. 1897 */ 1898 if (swapblk == SWAPBLK_NONE && 1899 swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 1900 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, rdpi); 1901 uma_zfree(swblk_zone, sb); 1902 } 1903 } 1904 1905 /* 1906 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 1907 * 1908 * The requested range of blocks is freed, with any associated swap 1909 * returned to the swap bitmap. 1910 * 1911 * This routine will free swap metadata structures as they are cleaned 1912 * out. This routine does *NOT* operate on swap metadata associated 1913 * with resident pages. 1914 */ 1915 static void 1916 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count) 1917 { 1918 struct swblk *sb; 1919 daddr_t first_free, num_free; 1920 vm_pindex_t last; 1921 int i, limit, start; 1922 1923 VM_OBJECT_ASSERT_WLOCKED(object); 1924 if (object->type != OBJT_SWAP || count == 0) 1925 return; 1926 1927 first_free = SWAPBLK_NONE; 1928 num_free = 0; 1929 last = pindex + count; 1930 for (;;) { 1931 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 1932 rounddown(pindex, SWAP_META_PAGES)); 1933 if (sb == NULL || sb->p >= last) 1934 break; 1935 start = pindex > sb->p ? pindex - sb->p : 0; 1936 limit = last - sb->p < SWAP_META_PAGES ? last - sb->p : 1937 SWAP_META_PAGES; 1938 for (i = start; i < limit; i++) { 1939 if (sb->d[i] == SWAPBLK_NONE) 1940 continue; 1941 if (first_free + num_free == sb->d[i]) 1942 num_free++; 1943 else { 1944 swp_pager_freeswapspace(first_free, num_free); 1945 first_free = sb->d[i]; 1946 num_free = 1; 1947 } 1948 sb->d[i] = SWAPBLK_NONE; 1949 } 1950 if (swp_pager_swblk_empty(sb, 0, start) && 1951 swp_pager_swblk_empty(sb, limit, SWAP_META_PAGES)) { 1952 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, 1953 sb->p); 1954 uma_zfree(swblk_zone, sb); 1955 } 1956 pindex = sb->p + SWAP_META_PAGES; 1957 } 1958 swp_pager_freeswapspace(first_free, num_free); 1959 } 1960 1961 /* 1962 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 1963 * 1964 * This routine locates and destroys all swap metadata associated with 1965 * an object. 1966 */ 1967 static void 1968 swp_pager_meta_free_all(vm_object_t object) 1969 { 1970 struct swblk *sb; 1971 daddr_t first_free, num_free; 1972 vm_pindex_t pindex; 1973 int i; 1974 1975 VM_OBJECT_ASSERT_WLOCKED(object); 1976 if (object->type != OBJT_SWAP) 1977 return; 1978 1979 first_free = SWAPBLK_NONE; 1980 num_free = 0; 1981 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1982 &object->un_pager.swp.swp_blks, pindex)) != NULL;) { 1983 pindex = sb->p + SWAP_META_PAGES; 1984 for (i = 0; i < SWAP_META_PAGES; i++) { 1985 if (sb->d[i] == SWAPBLK_NONE) 1986 continue; 1987 if (first_free + num_free == sb->d[i]) 1988 num_free++; 1989 else { 1990 swp_pager_freeswapspace(first_free, num_free); 1991 first_free = sb->d[i]; 1992 num_free = 1; 1993 } 1994 } 1995 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 1996 uma_zfree(swblk_zone, sb); 1997 } 1998 swp_pager_freeswapspace(first_free, num_free); 1999 } 2000 2001 /* 2002 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. 2003 * 2004 * This routine is capable of looking up, popping, or freeing 2005 * swapblk assignments in the swap meta data or in the vm_page_t. 2006 * The routine typically returns the swapblk being looked-up, or popped, 2007 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block 2008 * was invalid. This routine will automatically free any invalid 2009 * meta-data swapblks. 2010 * 2011 * When acting on a busy resident page and paging is in progress, we 2012 * have to wait until paging is complete but otherwise can act on the 2013 * busy page. 2014 * 2015 * SWM_FREE remove and free swap block from metadata 2016 * SWM_POP remove from meta data but do not free.. pop it out 2017 */ 2018 static daddr_t 2019 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags) 2020 { 2021 struct swblk *sb; 2022 daddr_t r1; 2023 2024 if ((flags & (SWM_FREE | SWM_POP)) != 0) 2025 VM_OBJECT_ASSERT_WLOCKED(object); 2026 else 2027 VM_OBJECT_ASSERT_LOCKED(object); 2028 2029 /* 2030 * The meta data only exists if the object is OBJT_SWAP 2031 * and even then might not be allocated yet. 2032 */ 2033 if (object->type != OBJT_SWAP) 2034 return (SWAPBLK_NONE); 2035 2036 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2037 rounddown(pindex, SWAP_META_PAGES)); 2038 if (sb == NULL) 2039 return (SWAPBLK_NONE); 2040 r1 = sb->d[pindex % SWAP_META_PAGES]; 2041 if (r1 == SWAPBLK_NONE) 2042 return (SWAPBLK_NONE); 2043 if ((flags & (SWM_FREE | SWM_POP)) != 0) { 2044 sb->d[pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 2045 if (swp_pager_swblk_empty(sb, 0, SWAP_META_PAGES)) { 2046 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, 2047 rounddown(pindex, SWAP_META_PAGES)); 2048 uma_zfree(swblk_zone, sb); 2049 } 2050 } 2051 if ((flags & SWM_FREE) != 0) { 2052 swp_pager_freeswapspace(r1, 1); 2053 r1 = SWAPBLK_NONE; 2054 } 2055 return (r1); 2056 } 2057 2058 /* 2059 * Returns the least page index which is greater than or equal to the 2060 * parameter pindex and for which there is a swap block allocated. 2061 * Returns object's size if the object's type is not swap or if there 2062 * are no allocated swap blocks for the object after the requested 2063 * pindex. 2064 */ 2065 vm_pindex_t 2066 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2067 { 2068 struct swblk *sb; 2069 int i; 2070 2071 VM_OBJECT_ASSERT_LOCKED(object); 2072 if (object->type != OBJT_SWAP) 2073 return (object->size); 2074 2075 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2076 rounddown(pindex, SWAP_META_PAGES)); 2077 if (sb == NULL) 2078 return (object->size); 2079 if (sb->p < pindex) { 2080 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2081 if (sb->d[i] != SWAPBLK_NONE) 2082 return (sb->p + i); 2083 } 2084 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2085 roundup(pindex, SWAP_META_PAGES)); 2086 if (sb == NULL) 2087 return (object->size); 2088 } 2089 for (i = 0; i < SWAP_META_PAGES; i++) { 2090 if (sb->d[i] != SWAPBLK_NONE) 2091 return (sb->p + i); 2092 } 2093 2094 /* 2095 * We get here if a swblk is present in the trie but it 2096 * doesn't map any blocks. 2097 */ 2098 MPASS(0); 2099 return (object->size); 2100 } 2101 2102 /* 2103 * System call swapon(name) enables swapping on device name, 2104 * which must be in the swdevsw. Return EBUSY 2105 * if already swapping on this device. 2106 */ 2107 #ifndef _SYS_SYSPROTO_H_ 2108 struct swapon_args { 2109 char *name; 2110 }; 2111 #endif 2112 2113 /* 2114 * MPSAFE 2115 */ 2116 /* ARGSUSED */ 2117 int 2118 sys_swapon(struct thread *td, struct swapon_args *uap) 2119 { 2120 struct vattr attr; 2121 struct vnode *vp; 2122 struct nameidata nd; 2123 int error; 2124 2125 error = priv_check(td, PRIV_SWAPON); 2126 if (error) 2127 return (error); 2128 2129 sx_xlock(&swdev_syscall_lock); 2130 2131 /* 2132 * Swap metadata may not fit in the KVM if we have physical 2133 * memory of >1GB. 2134 */ 2135 if (swblk_zone == NULL) { 2136 error = ENOMEM; 2137 goto done; 2138 } 2139 2140 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2141 uap->name, td); 2142 error = namei(&nd); 2143 if (error) 2144 goto done; 2145 2146 NDFREE(&nd, NDF_ONLY_PNBUF); 2147 vp = nd.ni_vp; 2148 2149 if (vn_isdisk(vp, &error)) { 2150 error = swapongeom(vp); 2151 } else if (vp->v_type == VREG && 2152 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2153 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2154 /* 2155 * Allow direct swapping to NFS regular files in the same 2156 * way that nfs_mountroot() sets up diskless swapping. 2157 */ 2158 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2159 } 2160 2161 if (error) 2162 vrele(vp); 2163 done: 2164 sx_xunlock(&swdev_syscall_lock); 2165 return (error); 2166 } 2167 2168 /* 2169 * Check that the total amount of swap currently configured does not 2170 * exceed half the theoretical maximum. If it does, print a warning 2171 * message. 2172 */ 2173 static void 2174 swapon_check_swzone(void) 2175 { 2176 unsigned long maxpages, npages; 2177 2178 npages = swap_total / PAGE_SIZE; 2179 /* absolute maximum we can handle assuming 100% efficiency */ 2180 maxpages = uma_zone_get_max(swblk_zone) * SWAP_META_PAGES; 2181 2182 /* recommend using no more than half that amount */ 2183 if (npages > maxpages / 2) { 2184 printf("warning: total configured swap (%lu pages) " 2185 "exceeds maximum recommended amount (%lu pages).\n", 2186 npages, maxpages / 2); 2187 printf("warning: increase kern.maxswzone " 2188 "or reduce amount of swap.\n"); 2189 } 2190 } 2191 2192 static void 2193 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2194 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2195 { 2196 struct swdevt *sp, *tsp; 2197 swblk_t dvbase; 2198 u_long mblocks; 2199 2200 /* 2201 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2202 * First chop nblks off to page-align it, then convert. 2203 * 2204 * sw->sw_nblks is in page-sized chunks now too. 2205 */ 2206 nblks &= ~(ctodb(1) - 1); 2207 nblks = dbtoc(nblks); 2208 2209 /* 2210 * If we go beyond this, we get overflows in the radix 2211 * tree bitmap code. 2212 */ 2213 mblocks = 0x40000000 / BLIST_META_RADIX; 2214 if (nblks > mblocks) { 2215 printf( 2216 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2217 mblocks / 1024 / 1024 * PAGE_SIZE); 2218 nblks = mblocks; 2219 } 2220 2221 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2222 sp->sw_vp = vp; 2223 sp->sw_id = id; 2224 sp->sw_dev = dev; 2225 sp->sw_flags = 0; 2226 sp->sw_nblks = nblks; 2227 sp->sw_used = 0; 2228 sp->sw_strategy = strategy; 2229 sp->sw_close = close; 2230 sp->sw_flags = flags; 2231 2232 sp->sw_blist = blist_create(nblks, M_WAITOK); 2233 /* 2234 * Do not free the first two block in order to avoid overwriting 2235 * any bsd label at the front of the partition 2236 */ 2237 blist_free(sp->sw_blist, 2, nblks - 2); 2238 2239 dvbase = 0; 2240 mtx_lock(&sw_dev_mtx); 2241 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2242 if (tsp->sw_end >= dvbase) { 2243 /* 2244 * We put one uncovered page between the devices 2245 * in order to definitively prevent any cross-device 2246 * I/O requests 2247 */ 2248 dvbase = tsp->sw_end + 1; 2249 } 2250 } 2251 sp->sw_first = dvbase; 2252 sp->sw_end = dvbase + nblks; 2253 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2254 nswapdev++; 2255 swap_pager_avail += nblks - 2; 2256 swap_total += (vm_ooffset_t)nblks * PAGE_SIZE; 2257 swapon_check_swzone(); 2258 swp_sizecheck(); 2259 mtx_unlock(&sw_dev_mtx); 2260 EVENTHANDLER_INVOKE(swapon, sp); 2261 } 2262 2263 /* 2264 * SYSCALL: swapoff(devname) 2265 * 2266 * Disable swapping on the given device. 2267 * 2268 * XXX: Badly designed system call: it should use a device index 2269 * rather than filename as specification. We keep sw_vp around 2270 * only to make this work. 2271 */ 2272 #ifndef _SYS_SYSPROTO_H_ 2273 struct swapoff_args { 2274 char *name; 2275 }; 2276 #endif 2277 2278 /* 2279 * MPSAFE 2280 */ 2281 /* ARGSUSED */ 2282 int 2283 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2284 { 2285 struct vnode *vp; 2286 struct nameidata nd; 2287 struct swdevt *sp; 2288 int error; 2289 2290 error = priv_check(td, PRIV_SWAPOFF); 2291 if (error) 2292 return (error); 2293 2294 sx_xlock(&swdev_syscall_lock); 2295 2296 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2297 td); 2298 error = namei(&nd); 2299 if (error) 2300 goto done; 2301 NDFREE(&nd, NDF_ONLY_PNBUF); 2302 vp = nd.ni_vp; 2303 2304 mtx_lock(&sw_dev_mtx); 2305 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2306 if (sp->sw_vp == vp) 2307 break; 2308 } 2309 mtx_unlock(&sw_dev_mtx); 2310 if (sp == NULL) { 2311 error = EINVAL; 2312 goto done; 2313 } 2314 error = swapoff_one(sp, td->td_ucred); 2315 done: 2316 sx_xunlock(&swdev_syscall_lock); 2317 return (error); 2318 } 2319 2320 static int 2321 swapoff_one(struct swdevt *sp, struct ucred *cred) 2322 { 2323 u_long nblks; 2324 #ifdef MAC 2325 int error; 2326 #endif 2327 2328 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2329 #ifdef MAC 2330 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2331 error = mac_system_check_swapoff(cred, sp->sw_vp); 2332 (void) VOP_UNLOCK(sp->sw_vp, 0); 2333 if (error != 0) 2334 return (error); 2335 #endif 2336 nblks = sp->sw_nblks; 2337 2338 /* 2339 * We can turn off this swap device safely only if the 2340 * available virtual memory in the system will fit the amount 2341 * of data we will have to page back in, plus an epsilon so 2342 * the system doesn't become critically low on swap space. 2343 */ 2344 if (vm_cnt.v_free_count + swap_pager_avail < nblks + nswap_lowat) 2345 return (ENOMEM); 2346 2347 /* 2348 * Prevent further allocations on this device. 2349 */ 2350 mtx_lock(&sw_dev_mtx); 2351 sp->sw_flags |= SW_CLOSING; 2352 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2353 swap_total -= (vm_ooffset_t)nblks * PAGE_SIZE; 2354 mtx_unlock(&sw_dev_mtx); 2355 2356 /* 2357 * Page in the contents of the device and close it. 2358 */ 2359 swap_pager_swapoff(sp); 2360 2361 sp->sw_close(curthread, sp); 2362 mtx_lock(&sw_dev_mtx); 2363 sp->sw_id = NULL; 2364 TAILQ_REMOVE(&swtailq, sp, sw_list); 2365 nswapdev--; 2366 if (nswapdev == 0) { 2367 swap_pager_full = 2; 2368 swap_pager_almost_full = 1; 2369 } 2370 if (swdevhd == sp) 2371 swdevhd = NULL; 2372 mtx_unlock(&sw_dev_mtx); 2373 blist_destroy(sp->sw_blist); 2374 free(sp, M_VMPGDATA); 2375 return (0); 2376 } 2377 2378 void 2379 swapoff_all(void) 2380 { 2381 struct swdevt *sp, *spt; 2382 const char *devname; 2383 int error; 2384 2385 sx_xlock(&swdev_syscall_lock); 2386 2387 mtx_lock(&sw_dev_mtx); 2388 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2389 mtx_unlock(&sw_dev_mtx); 2390 if (vn_isdisk(sp->sw_vp, NULL)) 2391 devname = devtoname(sp->sw_vp->v_rdev); 2392 else 2393 devname = "[file]"; 2394 error = swapoff_one(sp, thread0.td_ucred); 2395 if (error != 0) { 2396 printf("Cannot remove swap device %s (error=%d), " 2397 "skipping.\n", devname, error); 2398 } else if (bootverbose) { 2399 printf("Swap device %s removed.\n", devname); 2400 } 2401 mtx_lock(&sw_dev_mtx); 2402 } 2403 mtx_unlock(&sw_dev_mtx); 2404 2405 sx_xunlock(&swdev_syscall_lock); 2406 } 2407 2408 void 2409 swap_pager_status(int *total, int *used) 2410 { 2411 struct swdevt *sp; 2412 2413 *total = 0; 2414 *used = 0; 2415 mtx_lock(&sw_dev_mtx); 2416 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2417 *total += sp->sw_nblks; 2418 *used += sp->sw_used; 2419 } 2420 mtx_unlock(&sw_dev_mtx); 2421 } 2422 2423 int 2424 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2425 { 2426 struct swdevt *sp; 2427 const char *tmp_devname; 2428 int error, n; 2429 2430 n = 0; 2431 error = ENOENT; 2432 mtx_lock(&sw_dev_mtx); 2433 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2434 if (n != name) { 2435 n++; 2436 continue; 2437 } 2438 xs->xsw_version = XSWDEV_VERSION; 2439 xs->xsw_dev = sp->sw_dev; 2440 xs->xsw_flags = sp->sw_flags; 2441 xs->xsw_nblks = sp->sw_nblks; 2442 xs->xsw_used = sp->sw_used; 2443 if (devname != NULL) { 2444 if (vn_isdisk(sp->sw_vp, NULL)) 2445 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2446 else 2447 tmp_devname = "[file]"; 2448 strncpy(devname, tmp_devname, len); 2449 } 2450 error = 0; 2451 break; 2452 } 2453 mtx_unlock(&sw_dev_mtx); 2454 return (error); 2455 } 2456 2457 #if defined(COMPAT_FREEBSD11) 2458 #define XSWDEV_VERSION_11 1 2459 struct xswdev11 { 2460 u_int xsw_version; 2461 uint32_t xsw_dev; 2462 int xsw_flags; 2463 int xsw_nblks; 2464 int xsw_used; 2465 }; 2466 #endif 2467 2468 static int 2469 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2470 { 2471 struct xswdev xs; 2472 #if defined(COMPAT_FREEBSD11) 2473 struct xswdev11 xs11; 2474 #endif 2475 int error; 2476 2477 if (arg2 != 1) /* name length */ 2478 return (EINVAL); 2479 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2480 if (error != 0) 2481 return (error); 2482 #if defined(COMPAT_FREEBSD11) 2483 if (req->oldlen == sizeof(xs11)) { 2484 xs11.xsw_version = XSWDEV_VERSION_11; 2485 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2486 xs11.xsw_flags = xs.xsw_flags; 2487 xs11.xsw_nblks = xs.xsw_nblks; 2488 xs11.xsw_used = xs.xsw_used; 2489 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2490 } else 2491 #endif 2492 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2493 return (error); 2494 } 2495 2496 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2497 "Number of swap devices"); 2498 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2499 sysctl_vm_swap_info, 2500 "Swap statistics by device"); 2501 2502 /* 2503 * Count the approximate swap usage in pages for a vmspace. The 2504 * shadowed or not yet copied on write swap blocks are not accounted. 2505 * The map must be locked. 2506 */ 2507 long 2508 vmspace_swap_count(struct vmspace *vmspace) 2509 { 2510 vm_map_t map; 2511 vm_map_entry_t cur; 2512 vm_object_t object; 2513 struct swblk *sb; 2514 vm_pindex_t e, pi; 2515 long count; 2516 int i; 2517 2518 map = &vmspace->vm_map; 2519 count = 0; 2520 2521 for (cur = map->header.next; cur != &map->header; cur = cur->next) { 2522 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 2523 continue; 2524 object = cur->object.vm_object; 2525 if (object == NULL || object->type != OBJT_SWAP) 2526 continue; 2527 VM_OBJECT_RLOCK(object); 2528 if (object->type != OBJT_SWAP) 2529 goto unlock; 2530 pi = OFF_TO_IDX(cur->offset); 2531 e = pi + OFF_TO_IDX(cur->end - cur->start); 2532 for (;; pi = sb->p + SWAP_META_PAGES) { 2533 sb = SWAP_PCTRIE_LOOKUP_GE( 2534 &object->un_pager.swp.swp_blks, pi); 2535 if (sb == NULL || sb->p >= e) 2536 break; 2537 for (i = 0; i < SWAP_META_PAGES; i++) { 2538 if (sb->p + i < e && 2539 sb->d[i] != SWAPBLK_NONE) 2540 count++; 2541 } 2542 } 2543 unlock: 2544 VM_OBJECT_RUNLOCK(object); 2545 } 2546 return (count); 2547 } 2548 2549 /* 2550 * GEOM backend 2551 * 2552 * Swapping onto disk devices. 2553 * 2554 */ 2555 2556 static g_orphan_t swapgeom_orphan; 2557 2558 static struct g_class g_swap_class = { 2559 .name = "SWAP", 2560 .version = G_VERSION, 2561 .orphan = swapgeom_orphan, 2562 }; 2563 2564 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2565 2566 2567 static void 2568 swapgeom_close_ev(void *arg, int flags) 2569 { 2570 struct g_consumer *cp; 2571 2572 cp = arg; 2573 g_access(cp, -1, -1, 0); 2574 g_detach(cp); 2575 g_destroy_consumer(cp); 2576 } 2577 2578 /* 2579 * Add a reference to the g_consumer for an inflight transaction. 2580 */ 2581 static void 2582 swapgeom_acquire(struct g_consumer *cp) 2583 { 2584 2585 mtx_assert(&sw_dev_mtx, MA_OWNED); 2586 cp->index++; 2587 } 2588 2589 /* 2590 * Remove a reference from the g_consumer. Post a close event if all 2591 * references go away, since the function might be called from the 2592 * biodone context. 2593 */ 2594 static void 2595 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2596 { 2597 2598 mtx_assert(&sw_dev_mtx, MA_OWNED); 2599 cp->index--; 2600 if (cp->index == 0) { 2601 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2602 sp->sw_id = NULL; 2603 } 2604 } 2605 2606 static void 2607 swapgeom_done(struct bio *bp2) 2608 { 2609 struct swdevt *sp; 2610 struct buf *bp; 2611 struct g_consumer *cp; 2612 2613 bp = bp2->bio_caller2; 2614 cp = bp2->bio_from; 2615 bp->b_ioflags = bp2->bio_flags; 2616 if (bp2->bio_error) 2617 bp->b_ioflags |= BIO_ERROR; 2618 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2619 bp->b_error = bp2->bio_error; 2620 bufdone(bp); 2621 sp = bp2->bio_caller1; 2622 mtx_lock(&sw_dev_mtx); 2623 swapgeom_release(cp, sp); 2624 mtx_unlock(&sw_dev_mtx); 2625 g_destroy_bio(bp2); 2626 } 2627 2628 static void 2629 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2630 { 2631 struct bio *bio; 2632 struct g_consumer *cp; 2633 2634 mtx_lock(&sw_dev_mtx); 2635 cp = sp->sw_id; 2636 if (cp == NULL) { 2637 mtx_unlock(&sw_dev_mtx); 2638 bp->b_error = ENXIO; 2639 bp->b_ioflags |= BIO_ERROR; 2640 bufdone(bp); 2641 return; 2642 } 2643 swapgeom_acquire(cp); 2644 mtx_unlock(&sw_dev_mtx); 2645 if (bp->b_iocmd == BIO_WRITE) 2646 bio = g_new_bio(); 2647 else 2648 bio = g_alloc_bio(); 2649 if (bio == NULL) { 2650 mtx_lock(&sw_dev_mtx); 2651 swapgeom_release(cp, sp); 2652 mtx_unlock(&sw_dev_mtx); 2653 bp->b_error = ENOMEM; 2654 bp->b_ioflags |= BIO_ERROR; 2655 bufdone(bp); 2656 return; 2657 } 2658 2659 bio->bio_caller1 = sp; 2660 bio->bio_caller2 = bp; 2661 bio->bio_cmd = bp->b_iocmd; 2662 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2663 bio->bio_length = bp->b_bcount; 2664 bio->bio_done = swapgeom_done; 2665 if (!buf_mapped(bp)) { 2666 bio->bio_ma = bp->b_pages; 2667 bio->bio_data = unmapped_buf; 2668 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2669 bio->bio_ma_n = bp->b_npages; 2670 bio->bio_flags |= BIO_UNMAPPED; 2671 } else { 2672 bio->bio_data = bp->b_data; 2673 bio->bio_ma = NULL; 2674 } 2675 g_io_request(bio, cp); 2676 return; 2677 } 2678 2679 static void 2680 swapgeom_orphan(struct g_consumer *cp) 2681 { 2682 struct swdevt *sp; 2683 int destroy; 2684 2685 mtx_lock(&sw_dev_mtx); 2686 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2687 if (sp->sw_id == cp) { 2688 sp->sw_flags |= SW_CLOSING; 2689 break; 2690 } 2691 } 2692 /* 2693 * Drop reference we were created with. Do directly since we're in a 2694 * special context where we don't have to queue the call to 2695 * swapgeom_close_ev(). 2696 */ 2697 cp->index--; 2698 destroy = ((sp != NULL) && (cp->index == 0)); 2699 if (destroy) 2700 sp->sw_id = NULL; 2701 mtx_unlock(&sw_dev_mtx); 2702 if (destroy) 2703 swapgeom_close_ev(cp, 0); 2704 } 2705 2706 static void 2707 swapgeom_close(struct thread *td, struct swdevt *sw) 2708 { 2709 struct g_consumer *cp; 2710 2711 mtx_lock(&sw_dev_mtx); 2712 cp = sw->sw_id; 2713 sw->sw_id = NULL; 2714 mtx_unlock(&sw_dev_mtx); 2715 2716 /* 2717 * swapgeom_close() may be called from the biodone context, 2718 * where we cannot perform topology changes. Delegate the 2719 * work to the events thread. 2720 */ 2721 if (cp != NULL) 2722 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2723 } 2724 2725 static int 2726 swapongeom_locked(struct cdev *dev, struct vnode *vp) 2727 { 2728 struct g_provider *pp; 2729 struct g_consumer *cp; 2730 static struct g_geom *gp; 2731 struct swdevt *sp; 2732 u_long nblks; 2733 int error; 2734 2735 pp = g_dev_getprovider(dev); 2736 if (pp == NULL) 2737 return (ENODEV); 2738 mtx_lock(&sw_dev_mtx); 2739 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2740 cp = sp->sw_id; 2741 if (cp != NULL && cp->provider == pp) { 2742 mtx_unlock(&sw_dev_mtx); 2743 return (EBUSY); 2744 } 2745 } 2746 mtx_unlock(&sw_dev_mtx); 2747 if (gp == NULL) 2748 gp = g_new_geomf(&g_swap_class, "swap"); 2749 cp = g_new_consumer(gp); 2750 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2751 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2752 g_attach(cp, pp); 2753 /* 2754 * XXX: Every time you think you can improve the margin for 2755 * footshooting, somebody depends on the ability to do so: 2756 * savecore(8) wants to write to our swapdev so we cannot 2757 * set an exclusive count :-( 2758 */ 2759 error = g_access(cp, 1, 1, 0); 2760 if (error != 0) { 2761 g_detach(cp); 2762 g_destroy_consumer(cp); 2763 return (error); 2764 } 2765 nblks = pp->mediasize / DEV_BSIZE; 2766 swaponsomething(vp, cp, nblks, swapgeom_strategy, 2767 swapgeom_close, dev2udev(dev), 2768 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2769 return (0); 2770 } 2771 2772 static int 2773 swapongeom(struct vnode *vp) 2774 { 2775 int error; 2776 2777 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2778 if (vp->v_type != VCHR || (vp->v_iflag & VI_DOOMED) != 0) { 2779 error = ENOENT; 2780 } else { 2781 g_topology_lock(); 2782 error = swapongeom_locked(vp->v_rdev, vp); 2783 g_topology_unlock(); 2784 } 2785 VOP_UNLOCK(vp, 0); 2786 return (error); 2787 } 2788 2789 /* 2790 * VNODE backend 2791 * 2792 * This is used mainly for network filesystem (read: probably only tested 2793 * with NFS) swapfiles. 2794 * 2795 */ 2796 2797 static void 2798 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2799 { 2800 struct vnode *vp2; 2801 2802 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2803 2804 vp2 = sp->sw_id; 2805 vhold(vp2); 2806 if (bp->b_iocmd == BIO_WRITE) { 2807 if (bp->b_bufobj) 2808 bufobj_wdrop(bp->b_bufobj); 2809 bufobj_wref(&vp2->v_bufobj); 2810 } 2811 if (bp->b_bufobj != &vp2->v_bufobj) 2812 bp->b_bufobj = &vp2->v_bufobj; 2813 bp->b_vp = vp2; 2814 bp->b_iooffset = dbtob(bp->b_blkno); 2815 bstrategy(bp); 2816 return; 2817 } 2818 2819 static void 2820 swapdev_close(struct thread *td, struct swdevt *sp) 2821 { 2822 2823 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2824 vrele(sp->sw_vp); 2825 } 2826 2827 2828 static int 2829 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2830 { 2831 struct swdevt *sp; 2832 int error; 2833 2834 if (nblks == 0) 2835 return (ENXIO); 2836 mtx_lock(&sw_dev_mtx); 2837 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2838 if (sp->sw_id == vp) { 2839 mtx_unlock(&sw_dev_mtx); 2840 return (EBUSY); 2841 } 2842 } 2843 mtx_unlock(&sw_dev_mtx); 2844 2845 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2846 #ifdef MAC 2847 error = mac_system_check_swapon(td->td_ucred, vp); 2848 if (error == 0) 2849 #endif 2850 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 2851 (void) VOP_UNLOCK(vp, 0); 2852 if (error) 2853 return (error); 2854 2855 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 2856 NODEV, 0); 2857 return (0); 2858 } 2859 2860 static int 2861 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 2862 { 2863 int error, new, n; 2864 2865 new = nsw_wcount_async_max; 2866 error = sysctl_handle_int(oidp, &new, 0, req); 2867 if (error != 0 || req->newptr == NULL) 2868 return (error); 2869 2870 if (new > nswbuf / 2 || new < 1) 2871 return (EINVAL); 2872 2873 mtx_lock(&pbuf_mtx); 2874 while (nsw_wcount_async_max != new) { 2875 /* 2876 * Adjust difference. If the current async count is too low, 2877 * we will need to sqeeze our update slowly in. Sleep with a 2878 * higher priority than getpbuf() to finish faster. 2879 */ 2880 n = new - nsw_wcount_async_max; 2881 if (nsw_wcount_async + n >= 0) { 2882 nsw_wcount_async += n; 2883 nsw_wcount_async_max += n; 2884 wakeup(&nsw_wcount_async); 2885 } else { 2886 nsw_wcount_async_max -= nsw_wcount_async; 2887 nsw_wcount_async = 0; 2888 msleep(&nsw_wcount_async, &pbuf_mtx, PSWP, 2889 "swpsysctl", 0); 2890 } 2891 } 2892 mtx_unlock(&pbuf_mtx); 2893 2894 return (0); 2895 } 2896