1 /*- 2 * Copyright (c) 1998 Matthew Dillon, 3 * Copyright (c) 1994 John S. Dyson 4 * Copyright (c) 1990 University of Utah. 5 * Copyright (c) 1982, 1986, 1989, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * This code is derived from software contributed to Berkeley by 9 * the Systems Programming Group of the University of Utah Computer 10 * Science Department. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 * 40 * New Swap System 41 * Matthew Dillon 42 * 43 * Radix Bitmap 'blists'. 44 * 45 * - The new swapper uses the new radix bitmap code. This should scale 46 * to arbitrarily small or arbitrarily large swap spaces and an almost 47 * arbitrary degree of fragmentation. 48 * 49 * Features: 50 * 51 * - on the fly reallocation of swap during putpages. The new system 52 * does not try to keep previously allocated swap blocks for dirty 53 * pages. 54 * 55 * - on the fly deallocation of swap 56 * 57 * - No more garbage collection required. Unnecessarily allocated swap 58 * blocks only exist for dirty vm_page_t's now and these are already 59 * cycled (in a high-load system) by the pager. We also do on-the-fly 60 * removal of invalidated swap blocks when a page is destroyed 61 * or renamed. 62 * 63 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$ 64 * 65 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94 66 * @(#)vm_swap.c 8.5 (Berkeley) 2/17/94 67 */ 68 69 #include <sys/cdefs.h> 70 __FBSDID("$FreeBSD$"); 71 72 #include "opt_compat.h" 73 #include "opt_swap.h" 74 #include "opt_vm.h" 75 76 #include <sys/param.h> 77 #include <sys/systm.h> 78 #include <sys/conf.h> 79 #include <sys/kernel.h> 80 #include <sys/priv.h> 81 #include <sys/proc.h> 82 #include <sys/bio.h> 83 #include <sys/buf.h> 84 #include <sys/disk.h> 85 #include <sys/fcntl.h> 86 #include <sys/mount.h> 87 #include <sys/namei.h> 88 #include <sys/vnode.h> 89 #include <sys/malloc.h> 90 #include <sys/pctrie.h> 91 #include <sys/racct.h> 92 #include <sys/resource.h> 93 #include <sys/resourcevar.h> 94 #include <sys/rwlock.h> 95 #include <sys/sysctl.h> 96 #include <sys/sysproto.h> 97 #include <sys/blist.h> 98 #include <sys/lock.h> 99 #include <sys/sx.h> 100 #include <sys/vmmeter.h> 101 102 #include <security/mac/mac_framework.h> 103 104 #include <vm/vm.h> 105 #include <vm/pmap.h> 106 #include <vm/vm_map.h> 107 #include <vm/vm_kern.h> 108 #include <vm/vm_object.h> 109 #include <vm/vm_page.h> 110 #include <vm/vm_pager.h> 111 #include <vm/vm_pageout.h> 112 #include <vm/vm_param.h> 113 #include <vm/swap_pager.h> 114 #include <vm/vm_extern.h> 115 #include <vm/uma.h> 116 117 #include <geom/geom.h> 118 119 /* 120 * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64. 121 * The 64-page limit is due to the radix code (kern/subr_blist.c). 122 */ 123 #ifndef MAX_PAGEOUT_CLUSTER 124 #define MAX_PAGEOUT_CLUSTER 32 125 #endif 126 127 #if !defined(SWB_NPAGES) 128 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER 129 #endif 130 131 #define SWAP_META_PAGES PCTRIE_COUNT 132 133 /* 134 * A swblk structure maps each page index within a 135 * SWAP_META_PAGES-aligned and sized range to the address of an 136 * on-disk swap block (or SWAPBLK_NONE). The collection of these 137 * mappings for an entire vm object is implemented as a pc-trie. 138 */ 139 struct swblk { 140 vm_pindex_t p; 141 daddr_t d[SWAP_META_PAGES]; 142 }; 143 144 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); 145 static struct mtx sw_dev_mtx; 146 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 147 static struct swdevt *swdevhd; /* Allocate from here next */ 148 static int nswapdev; /* Number of swap devices */ 149 int swap_pager_avail; 150 static struct sx swdev_syscall_lock; /* serialize swap(on|off) */ 151 152 static vm_ooffset_t swap_total; 153 SYSCTL_QUAD(_vm, OID_AUTO, swap_total, CTLFLAG_RD, &swap_total, 0, 154 "Total amount of available swap storage."); 155 static vm_ooffset_t swap_reserved; 156 SYSCTL_QUAD(_vm, OID_AUTO, swap_reserved, CTLFLAG_RD, &swap_reserved, 0, 157 "Amount of swap storage needed to back all allocated anonymous memory."); 158 static int overcommit = 0; 159 SYSCTL_INT(_vm, OID_AUTO, overcommit, CTLFLAG_RW, &overcommit, 0, 160 "Configure virtual memory overcommit behavior. See tuning(7) " 161 "for details."); 162 static unsigned long swzone; 163 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 164 "Actual size of swap metadata zone"); 165 static unsigned long swap_maxpages; 166 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, 167 "Maximum amount of swap supported"); 168 169 /* bits from overcommit */ 170 #define SWAP_RESERVE_FORCE_ON (1 << 0) 171 #define SWAP_RESERVE_RLIMIT_ON (1 << 1) 172 #define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2) 173 174 int 175 swap_reserve(vm_ooffset_t incr) 176 { 177 178 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 179 } 180 181 int 182 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 183 { 184 vm_ooffset_t r, s; 185 int res, error; 186 static int curfail; 187 static struct timeval lastfail; 188 struct uidinfo *uip; 189 190 uip = cred->cr_ruidinfo; 191 192 if (incr & PAGE_MASK) 193 panic("swap_reserve: & PAGE_MASK"); 194 195 #ifdef RACCT 196 if (racct_enable) { 197 PROC_LOCK(curproc); 198 error = racct_add(curproc, RACCT_SWAP, incr); 199 PROC_UNLOCK(curproc); 200 if (error != 0) 201 return (0); 202 } 203 #endif 204 205 res = 0; 206 mtx_lock(&sw_dev_mtx); 207 r = swap_reserved + incr; 208 if (overcommit & SWAP_RESERVE_ALLOW_NONWIRED) { 209 s = vm_cnt.v_page_count - vm_cnt.v_free_reserved - vm_cnt.v_wire_count; 210 s *= PAGE_SIZE; 211 } else 212 s = 0; 213 s += swap_total; 214 if ((overcommit & SWAP_RESERVE_FORCE_ON) == 0 || r <= s || 215 (error = priv_check(curthread, PRIV_VM_SWAP_NOQUOTA)) == 0) { 216 res = 1; 217 swap_reserved = r; 218 } 219 mtx_unlock(&sw_dev_mtx); 220 221 if (res) { 222 UIDINFO_VMSIZE_LOCK(uip); 223 if ((overcommit & SWAP_RESERVE_RLIMIT_ON) != 0 && 224 uip->ui_vmsize + incr > lim_cur(curthread, RLIMIT_SWAP) && 225 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT)) 226 res = 0; 227 else 228 uip->ui_vmsize += incr; 229 UIDINFO_VMSIZE_UNLOCK(uip); 230 if (!res) { 231 mtx_lock(&sw_dev_mtx); 232 swap_reserved -= incr; 233 mtx_unlock(&sw_dev_mtx); 234 } 235 } 236 if (!res && ppsratecheck(&lastfail, &curfail, 1)) { 237 printf("uid %d, pid %d: swap reservation for %jd bytes failed\n", 238 uip->ui_uid, curproc->p_pid, incr); 239 } 240 241 #ifdef RACCT 242 if (!res) { 243 PROC_LOCK(curproc); 244 racct_sub(curproc, RACCT_SWAP, incr); 245 PROC_UNLOCK(curproc); 246 } 247 #endif 248 249 return (res); 250 } 251 252 void 253 swap_reserve_force(vm_ooffset_t incr) 254 { 255 struct uidinfo *uip; 256 257 mtx_lock(&sw_dev_mtx); 258 swap_reserved += incr; 259 mtx_unlock(&sw_dev_mtx); 260 261 #ifdef RACCT 262 PROC_LOCK(curproc); 263 racct_add_force(curproc, RACCT_SWAP, incr); 264 PROC_UNLOCK(curproc); 265 #endif 266 267 uip = curthread->td_ucred->cr_ruidinfo; 268 PROC_LOCK(curproc); 269 UIDINFO_VMSIZE_LOCK(uip); 270 uip->ui_vmsize += incr; 271 UIDINFO_VMSIZE_UNLOCK(uip); 272 PROC_UNLOCK(curproc); 273 } 274 275 void 276 swap_release(vm_ooffset_t decr) 277 { 278 struct ucred *cred; 279 280 PROC_LOCK(curproc); 281 cred = curthread->td_ucred; 282 swap_release_by_cred(decr, cred); 283 PROC_UNLOCK(curproc); 284 } 285 286 void 287 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 288 { 289 struct uidinfo *uip; 290 291 uip = cred->cr_ruidinfo; 292 293 if (decr & PAGE_MASK) 294 panic("swap_release: & PAGE_MASK"); 295 296 mtx_lock(&sw_dev_mtx); 297 if (swap_reserved < decr) 298 panic("swap_reserved < decr"); 299 swap_reserved -= decr; 300 mtx_unlock(&sw_dev_mtx); 301 302 UIDINFO_VMSIZE_LOCK(uip); 303 if (uip->ui_vmsize < decr) 304 printf("negative vmsize for uid = %d\n", uip->ui_uid); 305 uip->ui_vmsize -= decr; 306 UIDINFO_VMSIZE_UNLOCK(uip); 307 308 racct_sub_cred(cred, RACCT_SWAP, decr); 309 } 310 311 #define SWM_FREE 0x02 /* free, period */ 312 #define SWM_POP 0x04 /* pop out */ 313 314 int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 315 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 316 static int nsw_rcount; /* free read buffers */ 317 static int nsw_wcount_sync; /* limit write buffers / synchronous */ 318 static int nsw_wcount_async; /* limit write buffers / asynchronous */ 319 static int nsw_wcount_async_max;/* assigned maximum */ 320 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 321 322 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 323 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 324 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 325 "Maximum running async swap ops"); 326 327 static struct sx sw_alloc_sx; 328 329 /* 330 * "named" and "unnamed" anon region objects. Try to reduce the overhead 331 * of searching a named list by hashing it just a little. 332 */ 333 334 #define NOBJLISTS 8 335 336 #define NOBJLIST(handle) \ 337 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 338 339 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 340 static uma_zone_t swblk_zone; 341 static uma_zone_t swpctrie_zone; 342 343 /* 344 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 345 * calls hooked from other parts of the VM system and do not appear here. 346 * (see vm/swap_pager.h). 347 */ 348 static vm_object_t 349 swap_pager_alloc(void *handle, vm_ooffset_t size, 350 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 351 static void swap_pager_dealloc(vm_object_t object); 352 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, 353 int *); 354 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, 355 int *, pgo_getpages_iodone_t, void *); 356 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 357 static boolean_t 358 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 359 static void swap_pager_init(void); 360 static void swap_pager_unswapped(vm_page_t); 361 static void swap_pager_swapoff(struct swdevt *sp); 362 363 struct pagerops swappagerops = { 364 .pgo_init = swap_pager_init, /* early system initialization of pager */ 365 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 366 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 367 .pgo_getpages = swap_pager_getpages, /* pagein */ 368 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 369 .pgo_putpages = swap_pager_putpages, /* pageout */ 370 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 371 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 372 }; 373 374 /* 375 * swap_*() routines are externally accessible. swp_*() routines are 376 * internal. 377 */ 378 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 379 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 380 381 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 382 "Maximum size of a swap block in pages"); 383 384 static void swp_sizecheck(void); 385 static void swp_pager_async_iodone(struct buf *bp); 386 static int swapongeom(struct vnode *); 387 static int swaponvp(struct thread *, struct vnode *, u_long); 388 static int swapoff_one(struct swdevt *sp, struct ucred *cred); 389 390 /* 391 * Swap bitmap functions 392 */ 393 static void swp_pager_freeswapspace(daddr_t blk, int npages); 394 static daddr_t swp_pager_getswapspace(int npages); 395 396 /* 397 * Metadata functions 398 */ 399 static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 400 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 401 static void swp_pager_meta_free_all(vm_object_t); 402 static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 403 404 static void * 405 swblk_trie_alloc(struct pctrie *ptree) 406 { 407 408 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? 409 M_USE_RESERVE : 0))); 410 } 411 412 static void 413 swblk_trie_free(struct pctrie *ptree, void *node) 414 { 415 416 uma_zfree(swpctrie_zone, node); 417 } 418 419 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); 420 421 /* 422 * SWP_SIZECHECK() - update swap_pager_full indication 423 * 424 * update the swap_pager_almost_full indication and warn when we are 425 * about to run out of swap space, using lowat/hiwat hysteresis. 426 * 427 * Clear swap_pager_full ( task killing ) indication when lowat is met. 428 * 429 * No restrictions on call 430 * This routine may not block. 431 */ 432 static void 433 swp_sizecheck(void) 434 { 435 436 if (swap_pager_avail < nswap_lowat) { 437 if (swap_pager_almost_full == 0) { 438 printf("swap_pager: out of swap space\n"); 439 swap_pager_almost_full = 1; 440 } 441 } else { 442 swap_pager_full = 0; 443 if (swap_pager_avail > nswap_hiwat) 444 swap_pager_almost_full = 0; 445 } 446 } 447 448 /* 449 * SWAP_PAGER_INIT() - initialize the swap pager! 450 * 451 * Expected to be started from system init. NOTE: This code is run 452 * before much else so be careful what you depend on. Most of the VM 453 * system has yet to be initialized at this point. 454 */ 455 static void 456 swap_pager_init(void) 457 { 458 /* 459 * Initialize object lists 460 */ 461 int i; 462 463 for (i = 0; i < NOBJLISTS; ++i) 464 TAILQ_INIT(&swap_pager_object_list[i]); 465 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 466 sx_init(&sw_alloc_sx, "swspsx"); 467 sx_init(&swdev_syscall_lock, "swsysc"); 468 } 469 470 /* 471 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 472 * 473 * Expected to be started from pageout process once, prior to entering 474 * its main loop. 475 */ 476 void 477 swap_pager_swap_init(void) 478 { 479 unsigned long n, n2; 480 481 /* 482 * Number of in-transit swap bp operations. Don't 483 * exhaust the pbufs completely. Make sure we 484 * initialize workable values (0 will work for hysteresis 485 * but it isn't very efficient). 486 * 487 * The nsw_cluster_max is constrained by the bp->b_pages[] 488 * array (MAXPHYS/PAGE_SIZE) and our locally defined 489 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 490 * constrained by the swap device interleave stripe size. 491 * 492 * Currently we hardwire nsw_wcount_async to 4. This limit is 493 * designed to prevent other I/O from having high latencies due to 494 * our pageout I/O. The value 4 works well for one or two active swap 495 * devices but is probably a little low if you have more. Even so, 496 * a higher value would probably generate only a limited improvement 497 * with three or four active swap devices since the system does not 498 * typically have to pageout at extreme bandwidths. We will want 499 * at least 2 per swap devices, and 4 is a pretty good value if you 500 * have one NFS swap device due to the command/ack latency over NFS. 501 * So it all works out pretty well. 502 */ 503 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER); 504 505 mtx_lock(&pbuf_mtx); 506 nsw_rcount = (nswbuf + 1) / 2; 507 nsw_wcount_sync = (nswbuf + 3) / 4; 508 nsw_wcount_async = 4; 509 nsw_wcount_async_max = nsw_wcount_async; 510 mtx_unlock(&pbuf_mtx); 511 512 /* 513 * Initialize our zone, guessing on the number we need based 514 * on the number of pages in the system. 515 */ 516 n = vm_cnt.v_page_count / 2; 517 if (maxswzone && n > maxswzone / sizeof(struct swblk)) 518 n = maxswzone / sizeof(struct swblk); 519 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, 520 pctrie_zone_init, NULL, UMA_ALIGN_PTR, 521 UMA_ZONE_NOFREE | UMA_ZONE_VM); 522 if (swpctrie_zone == NULL) 523 panic("failed to create swap pctrie zone."); 524 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, 525 NULL, NULL, _Alignof(struct swblk) - 1, 526 UMA_ZONE_NOFREE | UMA_ZONE_VM); 527 if (swblk_zone == NULL) 528 panic("failed to create swap blk zone."); 529 n2 = n; 530 do { 531 if (uma_zone_reserve_kva(swblk_zone, n)) 532 break; 533 /* 534 * if the allocation failed, try a zone two thirds the 535 * size of the previous attempt. 536 */ 537 n -= ((n + 2) / 3); 538 } while (n > 0); 539 if (n2 != n) 540 printf("Swap blk zone entries reduced from %lu to %lu.\n", 541 n2, n); 542 swap_maxpages = n * SWAP_META_PAGES; 543 swzone = n * sizeof(struct swblk); 544 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 545 printf("Cannot reserve swap pctrie zone, " 546 "reduce kern.maxswzone.\n"); 547 } 548 549 static vm_object_t 550 swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size, 551 vm_ooffset_t offset) 552 { 553 vm_object_t object; 554 555 if (cred != NULL) { 556 if (!swap_reserve_by_cred(size, cred)) 557 return (NULL); 558 crhold(cred); 559 } 560 561 /* 562 * The un_pager.swp.swp_blks trie is initialized by 563 * vm_object_allocate() to ensure the correct order of 564 * visibility to other threads. 565 */ 566 object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset + 567 PAGE_MASK + size)); 568 569 object->handle = handle; 570 if (cred != NULL) { 571 object->cred = cred; 572 object->charge = size; 573 } 574 return (object); 575 } 576 577 /* 578 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 579 * its metadata structures. 580 * 581 * This routine is called from the mmap and fork code to create a new 582 * OBJT_SWAP object. 583 * 584 * This routine must ensure that no live duplicate is created for 585 * the named object request, which is protected against by 586 * holding the sw_alloc_sx lock in case handle != NULL. 587 */ 588 static vm_object_t 589 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 590 vm_ooffset_t offset, struct ucred *cred) 591 { 592 vm_object_t object; 593 594 if (handle != NULL) { 595 /* 596 * Reference existing named region or allocate new one. There 597 * should not be a race here against swp_pager_meta_build() 598 * as called from vm_page_remove() in regards to the lookup 599 * of the handle. 600 */ 601 sx_xlock(&sw_alloc_sx); 602 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 603 if (object == NULL) { 604 object = swap_pager_alloc_init(handle, cred, size, 605 offset); 606 if (object != NULL) { 607 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 608 object, pager_object_list); 609 } 610 } 611 sx_xunlock(&sw_alloc_sx); 612 } else { 613 object = swap_pager_alloc_init(handle, cred, size, offset); 614 } 615 return (object); 616 } 617 618 /* 619 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 620 * 621 * The swap backing for the object is destroyed. The code is 622 * designed such that we can reinstantiate it later, but this 623 * routine is typically called only when the entire object is 624 * about to be destroyed. 625 * 626 * The object must be locked. 627 */ 628 static void 629 swap_pager_dealloc(vm_object_t object) 630 { 631 632 VM_OBJECT_ASSERT_WLOCKED(object); 633 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 634 635 /* 636 * Remove from list right away so lookups will fail if we block for 637 * pageout completion. 638 */ 639 if (object->handle != NULL) { 640 VM_OBJECT_WUNLOCK(object); 641 sx_xlock(&sw_alloc_sx); 642 TAILQ_REMOVE(NOBJLIST(object->handle), object, 643 pager_object_list); 644 sx_xunlock(&sw_alloc_sx); 645 VM_OBJECT_WLOCK(object); 646 } 647 648 vm_object_pip_wait(object, "swpdea"); 649 650 /* 651 * Free all remaining metadata. We only bother to free it from 652 * the swap meta data. We do not attempt to free swapblk's still 653 * associated with vm_page_t's for this object. We do not care 654 * if paging is still in progress on some objects. 655 */ 656 swp_pager_meta_free_all(object); 657 object->handle = NULL; 658 object->type = OBJT_DEAD; 659 } 660 661 /************************************************************************ 662 * SWAP PAGER BITMAP ROUTINES * 663 ************************************************************************/ 664 665 /* 666 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 667 * 668 * Allocate swap for the requested number of pages. The starting 669 * swap block number (a page index) is returned or SWAPBLK_NONE 670 * if the allocation failed. 671 * 672 * Also has the side effect of advising that somebody made a mistake 673 * when they configured swap and didn't configure enough. 674 * 675 * This routine may not sleep. 676 * 677 * We allocate in round-robin fashion from the configured devices. 678 */ 679 static daddr_t 680 swp_pager_getswapspace(int npages) 681 { 682 daddr_t blk; 683 struct swdevt *sp; 684 int i; 685 686 blk = SWAPBLK_NONE; 687 mtx_lock(&sw_dev_mtx); 688 sp = swdevhd; 689 for (i = 0; i < nswapdev; i++) { 690 if (sp == NULL) 691 sp = TAILQ_FIRST(&swtailq); 692 if (!(sp->sw_flags & SW_CLOSING)) { 693 blk = blist_alloc(sp->sw_blist, npages); 694 if (blk != SWAPBLK_NONE) { 695 blk += sp->sw_first; 696 sp->sw_used += npages; 697 swap_pager_avail -= npages; 698 swp_sizecheck(); 699 swdevhd = TAILQ_NEXT(sp, sw_list); 700 goto done; 701 } 702 } 703 sp = TAILQ_NEXT(sp, sw_list); 704 } 705 if (swap_pager_full != 2) { 706 printf("swap_pager_getswapspace(%d): failed\n", npages); 707 swap_pager_full = 2; 708 swap_pager_almost_full = 1; 709 } 710 swdevhd = NULL; 711 done: 712 mtx_unlock(&sw_dev_mtx); 713 return (blk); 714 } 715 716 static int 717 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 718 { 719 720 return (blk >= sp->sw_first && blk < sp->sw_end); 721 } 722 723 static void 724 swp_pager_strategy(struct buf *bp) 725 { 726 struct swdevt *sp; 727 728 mtx_lock(&sw_dev_mtx); 729 TAILQ_FOREACH(sp, &swtailq, sw_list) { 730 if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) { 731 mtx_unlock(&sw_dev_mtx); 732 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 733 unmapped_buf_allowed) { 734 bp->b_data = unmapped_buf; 735 bp->b_offset = 0; 736 } else { 737 pmap_qenter((vm_offset_t)bp->b_data, 738 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 739 } 740 sp->sw_strategy(bp, sp); 741 return; 742 } 743 } 744 panic("Swapdev not found"); 745 } 746 747 748 /* 749 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 750 * 751 * This routine returns the specified swap blocks back to the bitmap. 752 * 753 * This routine may not sleep. 754 */ 755 static void 756 swp_pager_freeswapspace(daddr_t blk, int npages) 757 { 758 struct swdevt *sp; 759 760 mtx_lock(&sw_dev_mtx); 761 TAILQ_FOREACH(sp, &swtailq, sw_list) { 762 if (blk >= sp->sw_first && blk < sp->sw_end) { 763 sp->sw_used -= npages; 764 /* 765 * If we are attempting to stop swapping on 766 * this device, we don't want to mark any 767 * blocks free lest they be reused. 768 */ 769 if ((sp->sw_flags & SW_CLOSING) == 0) { 770 blist_free(sp->sw_blist, blk - sp->sw_first, 771 npages); 772 swap_pager_avail += npages; 773 swp_sizecheck(); 774 } 775 mtx_unlock(&sw_dev_mtx); 776 return; 777 } 778 } 779 panic("Swapdev not found"); 780 } 781 782 /* 783 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 784 * range within an object. 785 * 786 * This is a globally accessible routine. 787 * 788 * This routine removes swapblk assignments from swap metadata. 789 * 790 * The external callers of this routine typically have already destroyed 791 * or renamed vm_page_t's associated with this range in the object so 792 * we should be ok. 793 * 794 * The object must be locked. 795 */ 796 void 797 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 798 { 799 800 swp_pager_meta_free(object, start, size); 801 } 802 803 /* 804 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 805 * 806 * Assigns swap blocks to the specified range within the object. The 807 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 808 * 809 * Returns 0 on success, -1 on failure. 810 */ 811 int 812 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 813 { 814 int n = 0; 815 daddr_t blk = SWAPBLK_NONE; 816 vm_pindex_t beg = start; /* save start index */ 817 818 VM_OBJECT_WLOCK(object); 819 while (size) { 820 if (n == 0) { 821 n = BLIST_MAX_ALLOC; 822 while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) { 823 n >>= 1; 824 if (n == 0) { 825 swp_pager_meta_free(object, beg, start - beg); 826 VM_OBJECT_WUNLOCK(object); 827 return (-1); 828 } 829 } 830 } 831 swp_pager_meta_build(object, start, blk); 832 --size; 833 ++start; 834 ++blk; 835 --n; 836 } 837 swp_pager_meta_free(object, start, n); 838 VM_OBJECT_WUNLOCK(object); 839 return (0); 840 } 841 842 /* 843 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 844 * and destroy the source. 845 * 846 * Copy any valid swapblks from the source to the destination. In 847 * cases where both the source and destination have a valid swapblk, 848 * we keep the destination's. 849 * 850 * This routine is allowed to sleep. It may sleep allocating metadata 851 * indirectly through swp_pager_meta_build() or if paging is still in 852 * progress on the source. 853 * 854 * The source object contains no vm_page_t's (which is just as well) 855 * 856 * The source object is of type OBJT_SWAP. 857 * 858 * The source and destination objects must be locked. 859 * Both object locks may temporarily be released. 860 */ 861 void 862 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 863 vm_pindex_t offset, int destroysource) 864 { 865 vm_pindex_t i; 866 867 VM_OBJECT_ASSERT_WLOCKED(srcobject); 868 VM_OBJECT_ASSERT_WLOCKED(dstobject); 869 870 /* 871 * If destroysource is set, we remove the source object from the 872 * swap_pager internal queue now. 873 */ 874 if (destroysource && srcobject->handle != NULL) { 875 vm_object_pip_add(srcobject, 1); 876 VM_OBJECT_WUNLOCK(srcobject); 877 vm_object_pip_add(dstobject, 1); 878 VM_OBJECT_WUNLOCK(dstobject); 879 sx_xlock(&sw_alloc_sx); 880 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 881 pager_object_list); 882 sx_xunlock(&sw_alloc_sx); 883 VM_OBJECT_WLOCK(dstobject); 884 vm_object_pip_wakeup(dstobject); 885 VM_OBJECT_WLOCK(srcobject); 886 vm_object_pip_wakeup(srcobject); 887 } 888 889 /* 890 * transfer source to destination. 891 */ 892 for (i = 0; i < dstobject->size; ++i) { 893 daddr_t dstaddr; 894 895 /* 896 * Locate (without changing) the swapblk on the destination, 897 * unless it is invalid in which case free it silently, or 898 * if the destination is a resident page, in which case the 899 * source is thrown away. 900 */ 901 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 902 903 if (dstaddr == SWAPBLK_NONE) { 904 /* 905 * Destination has no swapblk and is not resident, 906 * copy source. 907 */ 908 daddr_t srcaddr; 909 910 srcaddr = swp_pager_meta_ctl( 911 srcobject, 912 i + offset, 913 SWM_POP 914 ); 915 916 if (srcaddr != SWAPBLK_NONE) { 917 /* 918 * swp_pager_meta_build() can sleep. 919 */ 920 vm_object_pip_add(srcobject, 1); 921 VM_OBJECT_WUNLOCK(srcobject); 922 vm_object_pip_add(dstobject, 1); 923 swp_pager_meta_build(dstobject, i, srcaddr); 924 vm_object_pip_wakeup(dstobject); 925 VM_OBJECT_WLOCK(srcobject); 926 vm_object_pip_wakeup(srcobject); 927 } 928 } else { 929 /* 930 * Destination has valid swapblk or it is represented 931 * by a resident page. We destroy the sourceblock. 932 */ 933 934 swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE); 935 } 936 } 937 938 /* 939 * Free left over swap blocks in source. 940 * 941 * We have to revert the type to OBJT_DEFAULT so we do not accidentally 942 * double-remove the object from the swap queues. 943 */ 944 if (destroysource) { 945 swp_pager_meta_free_all(srcobject); 946 /* 947 * Reverting the type is not necessary, the caller is going 948 * to destroy srcobject directly, but I'm doing it here 949 * for consistency since we've removed the object from its 950 * queues. 951 */ 952 srcobject->type = OBJT_DEFAULT; 953 } 954 } 955 956 /* 957 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 958 * the requested page. 959 * 960 * We determine whether good backing store exists for the requested 961 * page and return TRUE if it does, FALSE if it doesn't. 962 * 963 * If TRUE, we also try to determine how much valid, contiguous backing 964 * store exists before and after the requested page. 965 */ 966 static boolean_t 967 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 968 int *after) 969 { 970 daddr_t blk, blk0; 971 int i; 972 973 VM_OBJECT_ASSERT_LOCKED(object); 974 975 /* 976 * do we have good backing store at the requested index ? 977 */ 978 blk0 = swp_pager_meta_ctl(object, pindex, 0); 979 if (blk0 == SWAPBLK_NONE) { 980 if (before) 981 *before = 0; 982 if (after) 983 *after = 0; 984 return (FALSE); 985 } 986 987 /* 988 * find backwards-looking contiguous good backing store 989 */ 990 if (before != NULL) { 991 for (i = 1; i < SWB_NPAGES; i++) { 992 if (i > pindex) 993 break; 994 blk = swp_pager_meta_ctl(object, pindex - i, 0); 995 if (blk != blk0 - i) 996 break; 997 } 998 *before = i - 1; 999 } 1000 1001 /* 1002 * find forward-looking contiguous good backing store 1003 */ 1004 if (after != NULL) { 1005 for (i = 1; i < SWB_NPAGES; i++) { 1006 blk = swp_pager_meta_ctl(object, pindex + i, 0); 1007 if (blk != blk0 + i) 1008 break; 1009 } 1010 *after = i - 1; 1011 } 1012 return (TRUE); 1013 } 1014 1015 /* 1016 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1017 * 1018 * This removes any associated swap backing store, whether valid or 1019 * not, from the page. 1020 * 1021 * This routine is typically called when a page is made dirty, at 1022 * which point any associated swap can be freed. MADV_FREE also 1023 * calls us in a special-case situation 1024 * 1025 * NOTE!!! If the page is clean and the swap was valid, the caller 1026 * should make the page dirty before calling this routine. This routine 1027 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1028 * depends on it. 1029 * 1030 * This routine may not sleep. 1031 * 1032 * The object containing the page must be locked. 1033 */ 1034 static void 1035 swap_pager_unswapped(vm_page_t m) 1036 { 1037 1038 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); 1039 } 1040 1041 /* 1042 * swap_pager_getpages() - bring pages in from swap 1043 * 1044 * Attempt to page in the pages in array "m" of length "count". The caller 1045 * may optionally specify that additional pages preceding and succeeding 1046 * the specified range be paged in. The number of such pages is returned 1047 * in the "rbehind" and "rahead" parameters, and they will be in the 1048 * inactive queue upon return. 1049 * 1050 * The pages in "m" must be busied and will remain busied upon return. 1051 */ 1052 static int 1053 swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind, 1054 int *rahead) 1055 { 1056 struct buf *bp; 1057 vm_page_t mpred, msucc, p; 1058 vm_pindex_t pindex; 1059 daddr_t blk; 1060 int i, j, maxahead, maxbehind, reqcount, shift; 1061 1062 reqcount = count; 1063 1064 VM_OBJECT_WUNLOCK(object); 1065 bp = getpbuf(&nsw_rcount); 1066 VM_OBJECT_WLOCK(object); 1067 1068 if (!swap_pager_haspage(object, m[0]->pindex, &maxbehind, &maxahead)) { 1069 relpbuf(bp, &nsw_rcount); 1070 return (VM_PAGER_FAIL); 1071 } 1072 1073 /* 1074 * Clip the readahead and readbehind ranges to exclude resident pages. 1075 */ 1076 if (rahead != NULL) { 1077 KASSERT(reqcount - 1 <= maxahead, 1078 ("page count %d extends beyond swap block", reqcount)); 1079 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1080 pindex = m[reqcount - 1]->pindex; 1081 msucc = TAILQ_NEXT(m[reqcount - 1], listq); 1082 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1083 *rahead = msucc->pindex - pindex - 1; 1084 } 1085 if (rbehind != NULL) { 1086 *rbehind = imin(*rbehind, maxbehind); 1087 pindex = m[0]->pindex; 1088 mpred = TAILQ_PREV(m[0], pglist, listq); 1089 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1090 *rbehind = pindex - mpred->pindex - 1; 1091 } 1092 1093 /* 1094 * Allocate readahead and readbehind pages. 1095 */ 1096 shift = rbehind != NULL ? *rbehind : 0; 1097 if (shift != 0) { 1098 for (i = 1; i <= shift; i++) { 1099 p = vm_page_alloc(object, m[0]->pindex - i, 1100 VM_ALLOC_NORMAL); 1101 if (p == NULL) { 1102 /* Shift allocated pages to the left. */ 1103 for (j = 0; j < i - 1; j++) 1104 bp->b_pages[j] = 1105 bp->b_pages[j + shift - i + 1]; 1106 break; 1107 } 1108 bp->b_pages[shift - i] = p; 1109 } 1110 shift = i - 1; 1111 *rbehind = shift; 1112 } 1113 for (i = 0; i < reqcount; i++) 1114 bp->b_pages[i + shift] = m[i]; 1115 if (rahead != NULL) { 1116 for (i = 0; i < *rahead; i++) { 1117 p = vm_page_alloc(object, 1118 m[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1119 if (p == NULL) 1120 break; 1121 bp->b_pages[shift + reqcount + i] = p; 1122 } 1123 *rahead = i; 1124 } 1125 if (rbehind != NULL) 1126 count += *rbehind; 1127 if (rahead != NULL) 1128 count += *rahead; 1129 1130 vm_object_pip_add(object, count); 1131 1132 for (i = 0; i < count; i++) 1133 bp->b_pages[i]->oflags |= VPO_SWAPINPROG; 1134 1135 pindex = bp->b_pages[0]->pindex; 1136 blk = swp_pager_meta_ctl(object, pindex, 0); 1137 KASSERT(blk != SWAPBLK_NONE, 1138 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1139 1140 VM_OBJECT_WUNLOCK(object); 1141 1142 bp->b_flags |= B_PAGING; 1143 bp->b_iocmd = BIO_READ; 1144 bp->b_iodone = swp_pager_async_iodone; 1145 bp->b_rcred = crhold(thread0.td_ucred); 1146 bp->b_wcred = crhold(thread0.td_ucred); 1147 bp->b_blkno = blk; 1148 bp->b_bcount = PAGE_SIZE * count; 1149 bp->b_bufsize = PAGE_SIZE * count; 1150 bp->b_npages = count; 1151 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1152 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1153 1154 VM_CNT_INC(v_swapin); 1155 VM_CNT_ADD(v_swappgsin, count); 1156 1157 /* 1158 * perform the I/O. NOTE!!! bp cannot be considered valid after 1159 * this point because we automatically release it on completion. 1160 * Instead, we look at the one page we are interested in which we 1161 * still hold a lock on even through the I/O completion. 1162 * 1163 * The other pages in our m[] array are also released on completion, 1164 * so we cannot assume they are valid anymore either. 1165 * 1166 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1167 */ 1168 BUF_KERNPROC(bp); 1169 swp_pager_strategy(bp); 1170 1171 /* 1172 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1173 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1174 * is set in the metadata for each page in the request. 1175 */ 1176 VM_OBJECT_WLOCK(object); 1177 while ((m[0]->oflags & VPO_SWAPINPROG) != 0) { 1178 m[0]->oflags |= VPO_SWAPSLEEP; 1179 VM_CNT_INC(v_intrans); 1180 if (VM_OBJECT_SLEEP(object, &object->paging_in_progress, PSWP, 1181 "swread", hz * 20)) { 1182 printf( 1183 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1184 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1185 } 1186 } 1187 1188 /* 1189 * If we had an unrecoverable read error pages will not be valid. 1190 */ 1191 for (i = 0; i < reqcount; i++) 1192 if (m[i]->valid != VM_PAGE_BITS_ALL) 1193 return (VM_PAGER_ERROR); 1194 1195 return (VM_PAGER_OK); 1196 1197 /* 1198 * A final note: in a low swap situation, we cannot deallocate swap 1199 * and mark a page dirty here because the caller is likely to mark 1200 * the page clean when we return, causing the page to possibly revert 1201 * to all-zero's later. 1202 */ 1203 } 1204 1205 /* 1206 * swap_pager_getpages_async(): 1207 * 1208 * Right now this is emulation of asynchronous operation on top of 1209 * swap_pager_getpages(). 1210 */ 1211 static int 1212 swap_pager_getpages_async(vm_object_t object, vm_page_t *m, int count, 1213 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1214 { 1215 int r, error; 1216 1217 r = swap_pager_getpages(object, m, count, rbehind, rahead); 1218 VM_OBJECT_WUNLOCK(object); 1219 switch (r) { 1220 case VM_PAGER_OK: 1221 error = 0; 1222 break; 1223 case VM_PAGER_ERROR: 1224 error = EIO; 1225 break; 1226 case VM_PAGER_FAIL: 1227 error = EINVAL; 1228 break; 1229 default: 1230 panic("unhandled swap_pager_getpages() error %d", r); 1231 } 1232 (iodone)(arg, m, count, error); 1233 VM_OBJECT_WLOCK(object); 1234 1235 return (r); 1236 } 1237 1238 /* 1239 * swap_pager_putpages: 1240 * 1241 * Assign swap (if necessary) and initiate I/O on the specified pages. 1242 * 1243 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1244 * are automatically converted to SWAP objects. 1245 * 1246 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1247 * vm_page reservation system coupled with properly written VFS devices 1248 * should ensure that no low-memory deadlock occurs. This is an area 1249 * which needs work. 1250 * 1251 * The parent has N vm_object_pip_add() references prior to 1252 * calling us and will remove references for rtvals[] that are 1253 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1254 * completion. 1255 * 1256 * The parent has soft-busy'd the pages it passes us and will unbusy 1257 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1258 * We need to unbusy the rest on I/O completion. 1259 */ 1260 static void 1261 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1262 int flags, int *rtvals) 1263 { 1264 int i, n; 1265 boolean_t sync; 1266 1267 if (count && m[0]->object != object) { 1268 panic("swap_pager_putpages: object mismatch %p/%p", 1269 object, 1270 m[0]->object 1271 ); 1272 } 1273 1274 /* 1275 * Step 1 1276 * 1277 * Turn object into OBJT_SWAP 1278 * check for bogus sysops 1279 * force sync if not pageout process 1280 */ 1281 if (object->type != OBJT_SWAP) 1282 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1283 VM_OBJECT_WUNLOCK(object); 1284 1285 n = 0; 1286 if (curproc != pageproc) 1287 sync = TRUE; 1288 else 1289 sync = (flags & VM_PAGER_PUT_SYNC) != 0; 1290 1291 /* 1292 * Step 2 1293 * 1294 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1295 * The page is left dirty until the pageout operation completes 1296 * successfully. 1297 */ 1298 for (i = 0; i < count; i += n) { 1299 int j; 1300 struct buf *bp; 1301 daddr_t blk; 1302 1303 /* 1304 * Maximum I/O size is limited by a number of factors. 1305 */ 1306 n = min(BLIST_MAX_ALLOC, count - i); 1307 n = min(n, nsw_cluster_max); 1308 1309 /* 1310 * Get biggest block of swap we can. If we fail, fall 1311 * back and try to allocate a smaller block. Don't go 1312 * overboard trying to allocate space if it would overly 1313 * fragment swap. 1314 */ 1315 while ( 1316 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE && 1317 n > 4 1318 ) { 1319 n >>= 1; 1320 } 1321 if (blk == SWAPBLK_NONE) { 1322 for (j = 0; j < n; ++j) 1323 rtvals[i+j] = VM_PAGER_FAIL; 1324 continue; 1325 } 1326 1327 /* 1328 * All I/O parameters have been satisfied, build the I/O 1329 * request and assign the swap space. 1330 */ 1331 if (sync == TRUE) { 1332 bp = getpbuf(&nsw_wcount_sync); 1333 } else { 1334 bp = getpbuf(&nsw_wcount_async); 1335 bp->b_flags = B_ASYNC; 1336 } 1337 bp->b_flags |= B_PAGING; 1338 bp->b_iocmd = BIO_WRITE; 1339 1340 bp->b_rcred = crhold(thread0.td_ucred); 1341 bp->b_wcred = crhold(thread0.td_ucred); 1342 bp->b_bcount = PAGE_SIZE * n; 1343 bp->b_bufsize = PAGE_SIZE * n; 1344 bp->b_blkno = blk; 1345 1346 VM_OBJECT_WLOCK(object); 1347 for (j = 0; j < n; ++j) { 1348 vm_page_t mreq = m[i+j]; 1349 1350 swp_pager_meta_build( 1351 mreq->object, 1352 mreq->pindex, 1353 blk + j 1354 ); 1355 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1356 mreq->oflags |= VPO_SWAPINPROG; 1357 bp->b_pages[j] = mreq; 1358 } 1359 VM_OBJECT_WUNLOCK(object); 1360 bp->b_npages = n; 1361 /* 1362 * Must set dirty range for NFS to work. 1363 */ 1364 bp->b_dirtyoff = 0; 1365 bp->b_dirtyend = bp->b_bcount; 1366 1367 VM_CNT_INC(v_swapout); 1368 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1369 1370 /* 1371 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1372 * can call the async completion routine at the end of a 1373 * synchronous I/O operation. Otherwise, our caller would 1374 * perform duplicate unbusy and wakeup operations on the page 1375 * and object, respectively. 1376 */ 1377 for (j = 0; j < n; j++) 1378 rtvals[i + j] = VM_PAGER_PEND; 1379 1380 /* 1381 * asynchronous 1382 * 1383 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1384 */ 1385 if (sync == FALSE) { 1386 bp->b_iodone = swp_pager_async_iodone; 1387 BUF_KERNPROC(bp); 1388 swp_pager_strategy(bp); 1389 continue; 1390 } 1391 1392 /* 1393 * synchronous 1394 * 1395 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1396 */ 1397 bp->b_iodone = bdone; 1398 swp_pager_strategy(bp); 1399 1400 /* 1401 * Wait for the sync I/O to complete. 1402 */ 1403 bwait(bp, PVM, "swwrt"); 1404 1405 /* 1406 * Now that we are through with the bp, we can call the 1407 * normal async completion, which frees everything up. 1408 */ 1409 swp_pager_async_iodone(bp); 1410 } 1411 VM_OBJECT_WLOCK(object); 1412 } 1413 1414 /* 1415 * swp_pager_async_iodone: 1416 * 1417 * Completion routine for asynchronous reads and writes from/to swap. 1418 * Also called manually by synchronous code to finish up a bp. 1419 * 1420 * This routine may not sleep. 1421 */ 1422 static void 1423 swp_pager_async_iodone(struct buf *bp) 1424 { 1425 int i; 1426 vm_object_t object = NULL; 1427 1428 /* 1429 * report error 1430 */ 1431 if (bp->b_ioflags & BIO_ERROR) { 1432 printf( 1433 "swap_pager: I/O error - %s failed; blkno %ld," 1434 "size %ld, error %d\n", 1435 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1436 (long)bp->b_blkno, 1437 (long)bp->b_bcount, 1438 bp->b_error 1439 ); 1440 } 1441 1442 /* 1443 * remove the mapping for kernel virtual 1444 */ 1445 if (buf_mapped(bp)) 1446 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1447 else 1448 bp->b_data = bp->b_kvabase; 1449 1450 if (bp->b_npages) { 1451 object = bp->b_pages[0]->object; 1452 VM_OBJECT_WLOCK(object); 1453 } 1454 1455 /* 1456 * cleanup pages. If an error occurs writing to swap, we are in 1457 * very serious trouble. If it happens to be a disk error, though, 1458 * we may be able to recover by reassigning the swap later on. So 1459 * in this case we remove the m->swapblk assignment for the page 1460 * but do not free it in the rlist. The errornous block(s) are thus 1461 * never reallocated as swap. Redirty the page and continue. 1462 */ 1463 for (i = 0; i < bp->b_npages; ++i) { 1464 vm_page_t m = bp->b_pages[i]; 1465 1466 m->oflags &= ~VPO_SWAPINPROG; 1467 if (m->oflags & VPO_SWAPSLEEP) { 1468 m->oflags &= ~VPO_SWAPSLEEP; 1469 wakeup(&object->paging_in_progress); 1470 } 1471 1472 if (bp->b_ioflags & BIO_ERROR) { 1473 /* 1474 * If an error occurs I'd love to throw the swapblk 1475 * away without freeing it back to swapspace, so it 1476 * can never be used again. But I can't from an 1477 * interrupt. 1478 */ 1479 if (bp->b_iocmd == BIO_READ) { 1480 /* 1481 * NOTE: for reads, m->dirty will probably 1482 * be overridden by the original caller of 1483 * getpages so don't play cute tricks here. 1484 */ 1485 m->valid = 0; 1486 } else { 1487 /* 1488 * If a write error occurs, reactivate page 1489 * so it doesn't clog the inactive list, 1490 * then finish the I/O. 1491 */ 1492 vm_page_dirty(m); 1493 vm_page_lock(m); 1494 vm_page_activate(m); 1495 vm_page_unlock(m); 1496 vm_page_sunbusy(m); 1497 } 1498 } else if (bp->b_iocmd == BIO_READ) { 1499 /* 1500 * NOTE: for reads, m->dirty will probably be 1501 * overridden by the original caller of getpages so 1502 * we cannot set them in order to free the underlying 1503 * swap in a low-swap situation. I don't think we'd 1504 * want to do that anyway, but it was an optimization 1505 * that existed in the old swapper for a time before 1506 * it got ripped out due to precisely this problem. 1507 */ 1508 KASSERT(!pmap_page_is_mapped(m), 1509 ("swp_pager_async_iodone: page %p is mapped", m)); 1510 KASSERT(m->dirty == 0, 1511 ("swp_pager_async_iodone: page %p is dirty", m)); 1512 1513 m->valid = VM_PAGE_BITS_ALL; 1514 if (i < bp->b_pgbefore || 1515 i >= bp->b_npages - bp->b_pgafter) 1516 vm_page_readahead_finish(m); 1517 } else { 1518 /* 1519 * For write success, clear the dirty 1520 * status, then finish the I/O ( which decrements the 1521 * busy count and possibly wakes waiter's up ). 1522 * A page is only written to swap after a period of 1523 * inactivity. Therefore, we do not expect it to be 1524 * reused. 1525 */ 1526 KASSERT(!pmap_page_is_write_mapped(m), 1527 ("swp_pager_async_iodone: page %p is not write" 1528 " protected", m)); 1529 vm_page_undirty(m); 1530 vm_page_lock(m); 1531 vm_page_deactivate_noreuse(m); 1532 vm_page_unlock(m); 1533 vm_page_sunbusy(m); 1534 } 1535 } 1536 1537 /* 1538 * adjust pip. NOTE: the original parent may still have its own 1539 * pip refs on the object. 1540 */ 1541 if (object != NULL) { 1542 vm_object_pip_wakeupn(object, bp->b_npages); 1543 VM_OBJECT_WUNLOCK(object); 1544 } 1545 1546 /* 1547 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1548 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1549 * trigger a KASSERT in relpbuf(). 1550 */ 1551 if (bp->b_vp) { 1552 bp->b_vp = NULL; 1553 bp->b_bufobj = NULL; 1554 } 1555 /* 1556 * release the physical I/O buffer 1557 */ 1558 relpbuf( 1559 bp, 1560 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount : 1561 ((bp->b_flags & B_ASYNC) ? 1562 &nsw_wcount_async : 1563 &nsw_wcount_sync 1564 ) 1565 ) 1566 ); 1567 } 1568 1569 int 1570 swap_pager_nswapdev(void) 1571 { 1572 1573 return (nswapdev); 1574 } 1575 1576 /* 1577 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in 1578 * 1579 * This routine dissociates the page at the given index within an object 1580 * from its backing store, paging it in if it does not reside in memory. 1581 * If the page is paged in, it is marked dirty and placed in the laundry 1582 * queue. The page is marked dirty because it no longer has backing 1583 * store. It is placed in the laundry queue because it has not been 1584 * accessed recently. Otherwise, it would already reside in memory. 1585 * 1586 * We also attempt to swap in all other pages in the swap block. 1587 * However, we only guarantee that the one at the specified index is 1588 * paged in. 1589 * 1590 * XXX - The code to page the whole block in doesn't work, so we 1591 * revert to the one-by-one behavior for now. Sigh. 1592 */ 1593 static inline void 1594 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex) 1595 { 1596 vm_page_t m; 1597 1598 vm_object_pip_add(object, 1); 1599 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL); 1600 if (m->valid == VM_PAGE_BITS_ALL) { 1601 vm_object_pip_wakeup(object); 1602 vm_page_dirty(m); 1603 vm_page_lock(m); 1604 vm_page_activate(m); 1605 vm_page_unlock(m); 1606 vm_page_xunbusy(m); 1607 vm_pager_page_unswapped(m); 1608 return; 1609 } 1610 1611 if (swap_pager_getpages(object, &m, 1, NULL, NULL) != VM_PAGER_OK) 1612 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/ 1613 vm_object_pip_wakeup(object); 1614 vm_page_dirty(m); 1615 vm_page_lock(m); 1616 vm_page_launder(m); 1617 vm_page_unlock(m); 1618 vm_page_xunbusy(m); 1619 vm_pager_page_unswapped(m); 1620 } 1621 1622 /* 1623 * swap_pager_swapoff: 1624 * 1625 * Page in all of the pages that have been paged out to the 1626 * given device. The corresponding blocks in the bitmap must be 1627 * marked as allocated and the device must be flagged SW_CLOSING. 1628 * There may be no processes swapped out to the device. 1629 * 1630 * This routine may block. 1631 */ 1632 static void 1633 swap_pager_swapoff(struct swdevt *sp) 1634 { 1635 struct swblk *sb; 1636 vm_object_t object; 1637 vm_pindex_t pi; 1638 int i, retries; 1639 1640 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 1641 1642 retries = 0; 1643 full_rescan: 1644 mtx_lock(&vm_object_list_mtx); 1645 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1646 if (object->type != OBJT_SWAP) 1647 continue; 1648 mtx_unlock(&vm_object_list_mtx); 1649 /* Depends on type-stability. */ 1650 VM_OBJECT_WLOCK(object); 1651 1652 /* 1653 * Dead objects are eventually terminated on their own. 1654 */ 1655 if ((object->flags & OBJ_DEAD) != 0) 1656 goto next_obj; 1657 1658 /* 1659 * Sync with fences placed after pctrie 1660 * initialization. We must not access pctrie below 1661 * unless we checked that our object is swap and not 1662 * dead. 1663 */ 1664 atomic_thread_fence_acq(); 1665 if (object->type != OBJT_SWAP) 1666 goto next_obj; 1667 1668 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1669 &object->un_pager.swp.swp_blks, pi)) != NULL; ) { 1670 pi = sb->p + SWAP_META_PAGES; 1671 for (i = 0; i < SWAP_META_PAGES; i++) { 1672 if (sb->d[i] == SWAPBLK_NONE) 1673 continue; 1674 if (swp_pager_isondev(sb->d[i], sp)) 1675 swp_pager_force_pagein(object, 1676 sb->p + i); 1677 } 1678 } 1679 next_obj: 1680 VM_OBJECT_WUNLOCK(object); 1681 mtx_lock(&vm_object_list_mtx); 1682 } 1683 mtx_unlock(&vm_object_list_mtx); 1684 1685 if (sp->sw_used) { 1686 /* 1687 * Objects may be locked or paging to the device being 1688 * removed, so we will miss their pages and need to 1689 * make another pass. We have marked this device as 1690 * SW_CLOSING, so the activity should finish soon. 1691 */ 1692 retries++; 1693 if (retries > 100) { 1694 panic("swapoff: failed to locate %d swap blocks", 1695 sp->sw_used); 1696 } 1697 pause("swpoff", hz / 20); 1698 goto full_rescan; 1699 } 1700 EVENTHANDLER_INVOKE(swapoff, sp); 1701 } 1702 1703 /************************************************************************ 1704 * SWAP META DATA * 1705 ************************************************************************ 1706 * 1707 * These routines manipulate the swap metadata stored in the 1708 * OBJT_SWAP object. 1709 * 1710 * Swap metadata is implemented with a global hash and not directly 1711 * linked into the object. Instead the object simply contains 1712 * appropriate tracking counters. 1713 */ 1714 1715 /* 1716 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1717 * 1718 * We first convert the object to a swap object if it is a default 1719 * object. 1720 * 1721 * The specified swapblk is added to the object's swap metadata. If 1722 * the swapblk is not valid, it is freed instead. Any previously 1723 * assigned swapblk is freed. 1724 */ 1725 static void 1726 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1727 { 1728 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 1729 struct swblk *sb; 1730 vm_pindex_t modpi, rdpi; 1731 int error, i; 1732 1733 VM_OBJECT_ASSERT_WLOCKED(object); 1734 1735 /* 1736 * Convert default object to swap object if necessary 1737 */ 1738 if (object->type != OBJT_SWAP) { 1739 pctrie_init(&object->un_pager.swp.swp_blks); 1740 1741 /* 1742 * Ensure that swap_pager_swapoff()'s iteration over 1743 * object_list does not see a garbage pctrie. 1744 */ 1745 atomic_thread_fence_rel(); 1746 1747 object->type = OBJT_SWAP; 1748 KASSERT(object->handle == NULL, ("default pager with handle")); 1749 } 1750 1751 rdpi = rounddown(pindex, SWAP_META_PAGES); 1752 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi); 1753 if (sb == NULL) { 1754 if (swapblk == SWAPBLK_NONE) 1755 return; 1756 for (;;) { 1757 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 1758 pageproc ? M_USE_RESERVE : 0)); 1759 if (sb != NULL) { 1760 sb->p = rdpi; 1761 for (i = 0; i < SWAP_META_PAGES; i++) 1762 sb->d[i] = SWAPBLK_NONE; 1763 if (atomic_cmpset_int(&swblk_zone_exhausted, 1764 1, 0)) 1765 printf("swblk zone ok\n"); 1766 break; 1767 } 1768 VM_OBJECT_WUNLOCK(object); 1769 if (uma_zone_exhausted(swblk_zone)) { 1770 if (atomic_cmpset_int(&swblk_zone_exhausted, 1771 0, 1)) 1772 printf("swap blk zone exhausted, " 1773 "increase kern.maxswzone\n"); 1774 vm_pageout_oom(VM_OOM_SWAPZ); 1775 pause("swzonxb", 10); 1776 } else 1777 VM_WAIT; 1778 VM_OBJECT_WLOCK(object); 1779 } 1780 for (;;) { 1781 error = SWAP_PCTRIE_INSERT( 1782 &object->un_pager.swp.swp_blks, sb); 1783 if (error == 0) { 1784 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1785 1, 0)) 1786 printf("swpctrie zone ok\n"); 1787 break; 1788 } 1789 VM_OBJECT_WUNLOCK(object); 1790 if (uma_zone_exhausted(swpctrie_zone)) { 1791 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1792 0, 1)) 1793 printf("swap pctrie zone exhausted, " 1794 "increase kern.maxswzone\n"); 1795 vm_pageout_oom(VM_OOM_SWAPZ); 1796 pause("swzonxp", 10); 1797 } else 1798 VM_WAIT; 1799 VM_OBJECT_WLOCK(object); 1800 } 1801 } 1802 MPASS(sb->p == rdpi); 1803 1804 modpi = pindex % SWAP_META_PAGES; 1805 /* Delete prior contents of metadata. */ 1806 if (sb->d[modpi] != SWAPBLK_NONE) 1807 swp_pager_freeswapspace(sb->d[modpi], 1); 1808 /* Enter block into metadata. */ 1809 sb->d[modpi] = swapblk; 1810 } 1811 1812 /* 1813 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 1814 * 1815 * The requested range of blocks is freed, with any associated swap 1816 * returned to the swap bitmap. 1817 * 1818 * This routine will free swap metadata structures as they are cleaned 1819 * out. This routine does *NOT* operate on swap metadata associated 1820 * with resident pages. 1821 */ 1822 static void 1823 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count) 1824 { 1825 struct swblk *sb; 1826 vm_pindex_t last; 1827 int i; 1828 bool empty; 1829 1830 VM_OBJECT_ASSERT_LOCKED(object); 1831 if (object->type != OBJT_SWAP || count == 0) 1832 return; 1833 1834 last = pindex + count - 1; 1835 for (;;) { 1836 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 1837 rounddown(pindex, SWAP_META_PAGES)); 1838 if (sb == NULL || sb->p > last) 1839 break; 1840 empty = true; 1841 for (i = 0; i < SWAP_META_PAGES; i++) { 1842 if (sb->d[i] == SWAPBLK_NONE) 1843 continue; 1844 if (pindex <= sb->p + i && sb->p + i <= last) { 1845 swp_pager_freeswapspace(sb->d[i], 1); 1846 sb->d[i] = SWAPBLK_NONE; 1847 } else 1848 empty = false; 1849 } 1850 pindex = sb->p + SWAP_META_PAGES; 1851 if (empty) { 1852 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, 1853 sb->p); 1854 uma_zfree(swblk_zone, sb); 1855 } 1856 } 1857 } 1858 1859 /* 1860 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 1861 * 1862 * This routine locates and destroys all swap metadata associated with 1863 * an object. 1864 */ 1865 static void 1866 swp_pager_meta_free_all(vm_object_t object) 1867 { 1868 struct swblk *sb; 1869 vm_pindex_t pindex; 1870 int i; 1871 1872 VM_OBJECT_ASSERT_WLOCKED(object); 1873 if (object->type != OBJT_SWAP) 1874 return; 1875 1876 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1877 &object->un_pager.swp.swp_blks, pindex)) != NULL;) { 1878 pindex = sb->p + SWAP_META_PAGES; 1879 for (i = 0; i < SWAP_META_PAGES; i++) { 1880 if (sb->d[i] != SWAPBLK_NONE) 1881 swp_pager_freeswapspace(sb->d[i], 1); 1882 } 1883 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 1884 uma_zfree(swblk_zone, sb); 1885 } 1886 } 1887 1888 /* 1889 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. 1890 * 1891 * This routine is capable of looking up, popping, or freeing 1892 * swapblk assignments in the swap meta data or in the vm_page_t. 1893 * The routine typically returns the swapblk being looked-up, or popped, 1894 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block 1895 * was invalid. This routine will automatically free any invalid 1896 * meta-data swapblks. 1897 * 1898 * When acting on a busy resident page and paging is in progress, we 1899 * have to wait until paging is complete but otherwise can act on the 1900 * busy page. 1901 * 1902 * SWM_FREE remove and free swap block from metadata 1903 * SWM_POP remove from meta data but do not free.. pop it out 1904 */ 1905 static daddr_t 1906 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags) 1907 { 1908 struct swblk *sb; 1909 daddr_t r1; 1910 int i; 1911 1912 VM_OBJECT_ASSERT_LOCKED(object); 1913 /* 1914 * The meta data only exists of the object is OBJT_SWAP 1915 * and even then might not be allocated yet. 1916 */ 1917 if (object->type != OBJT_SWAP) 1918 return (SWAPBLK_NONE); 1919 1920 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 1921 rounddown(pindex, SWAP_META_PAGES)); 1922 if (sb == NULL) 1923 return (SWAPBLK_NONE); 1924 r1 = sb->d[pindex % SWAP_META_PAGES]; 1925 if (r1 == SWAPBLK_NONE) 1926 return (SWAPBLK_NONE); 1927 if ((flags & (SWM_FREE | SWM_POP)) != 0) { 1928 sb->d[pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 1929 for (i = 0; i < SWAP_META_PAGES; i++) { 1930 if (sb->d[i] != SWAPBLK_NONE) 1931 break; 1932 } 1933 if (i == SWAP_META_PAGES) { 1934 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, 1935 rounddown(pindex, SWAP_META_PAGES)); 1936 uma_zfree(swblk_zone, sb); 1937 } 1938 } 1939 if ((flags & SWM_FREE) != 0) { 1940 swp_pager_freeswapspace(r1, 1); 1941 r1 = SWAPBLK_NONE; 1942 } 1943 return (r1); 1944 } 1945 1946 /* 1947 * Returns the least page index which is greater than or equal to the 1948 * parameter pindex and for which there is a swap block allocated. 1949 * Returns object's size if the object's type is not swap or if there 1950 * are no allocated swap blocks for the object after the requested 1951 * pindex. 1952 */ 1953 vm_pindex_t 1954 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 1955 { 1956 struct swblk *sb; 1957 int i; 1958 1959 VM_OBJECT_ASSERT_LOCKED(object); 1960 if (object->type != OBJT_SWAP) 1961 return (object->size); 1962 1963 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 1964 rounddown(pindex, SWAP_META_PAGES)); 1965 if (sb == NULL) 1966 return (object->size); 1967 if (sb->p < pindex) { 1968 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 1969 if (sb->d[i] != SWAPBLK_NONE) 1970 return (sb->p + i); 1971 } 1972 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 1973 roundup(pindex, SWAP_META_PAGES)); 1974 if (sb == NULL) 1975 return (object->size); 1976 } 1977 for (i = 0; i < SWAP_META_PAGES; i++) { 1978 if (sb->d[i] != SWAPBLK_NONE) 1979 return (sb->p + i); 1980 } 1981 1982 /* 1983 * We get here if a swblk is present in the trie but it 1984 * doesn't map any blocks. 1985 */ 1986 MPASS(0); 1987 return (object->size); 1988 } 1989 1990 /* 1991 * System call swapon(name) enables swapping on device name, 1992 * which must be in the swdevsw. Return EBUSY 1993 * if already swapping on this device. 1994 */ 1995 #ifndef _SYS_SYSPROTO_H_ 1996 struct swapon_args { 1997 char *name; 1998 }; 1999 #endif 2000 2001 /* 2002 * MPSAFE 2003 */ 2004 /* ARGSUSED */ 2005 int 2006 sys_swapon(struct thread *td, struct swapon_args *uap) 2007 { 2008 struct vattr attr; 2009 struct vnode *vp; 2010 struct nameidata nd; 2011 int error; 2012 2013 error = priv_check(td, PRIV_SWAPON); 2014 if (error) 2015 return (error); 2016 2017 sx_xlock(&swdev_syscall_lock); 2018 2019 /* 2020 * Swap metadata may not fit in the KVM if we have physical 2021 * memory of >1GB. 2022 */ 2023 if (swblk_zone == NULL) { 2024 error = ENOMEM; 2025 goto done; 2026 } 2027 2028 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2029 uap->name, td); 2030 error = namei(&nd); 2031 if (error) 2032 goto done; 2033 2034 NDFREE(&nd, NDF_ONLY_PNBUF); 2035 vp = nd.ni_vp; 2036 2037 if (vn_isdisk(vp, &error)) { 2038 error = swapongeom(vp); 2039 } else if (vp->v_type == VREG && 2040 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2041 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2042 /* 2043 * Allow direct swapping to NFS regular files in the same 2044 * way that nfs_mountroot() sets up diskless swapping. 2045 */ 2046 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2047 } 2048 2049 if (error) 2050 vrele(vp); 2051 done: 2052 sx_xunlock(&swdev_syscall_lock); 2053 return (error); 2054 } 2055 2056 /* 2057 * Check that the total amount of swap currently configured does not 2058 * exceed half the theoretical maximum. If it does, print a warning 2059 * message and return -1; otherwise, return 0. 2060 */ 2061 static int 2062 swapon_check_swzone(unsigned long npages) 2063 { 2064 unsigned long maxpages; 2065 2066 /* absolute maximum we can handle assuming 100% efficiency */ 2067 maxpages = uma_zone_get_max(swblk_zone) * SWAP_META_PAGES; 2068 2069 /* recommend using no more than half that amount */ 2070 if (npages > maxpages / 2) { 2071 printf("warning: total configured swap (%lu pages) " 2072 "exceeds maximum recommended amount (%lu pages).\n", 2073 npages, maxpages / 2); 2074 printf("warning: increase kern.maxswzone " 2075 "or reduce amount of swap.\n"); 2076 return (-1); 2077 } 2078 return (0); 2079 } 2080 2081 static void 2082 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2083 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2084 { 2085 struct swdevt *sp, *tsp; 2086 swblk_t dvbase; 2087 u_long mblocks; 2088 2089 /* 2090 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2091 * First chop nblks off to page-align it, then convert. 2092 * 2093 * sw->sw_nblks is in page-sized chunks now too. 2094 */ 2095 nblks &= ~(ctodb(1) - 1); 2096 nblks = dbtoc(nblks); 2097 2098 /* 2099 * If we go beyond this, we get overflows in the radix 2100 * tree bitmap code. 2101 */ 2102 mblocks = 0x40000000 / BLIST_META_RADIX; 2103 if (nblks > mblocks) { 2104 printf( 2105 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2106 mblocks / 1024 / 1024 * PAGE_SIZE); 2107 nblks = mblocks; 2108 } 2109 2110 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2111 sp->sw_vp = vp; 2112 sp->sw_id = id; 2113 sp->sw_dev = dev; 2114 sp->sw_flags = 0; 2115 sp->sw_nblks = nblks; 2116 sp->sw_used = 0; 2117 sp->sw_strategy = strategy; 2118 sp->sw_close = close; 2119 sp->sw_flags = flags; 2120 2121 sp->sw_blist = blist_create(nblks, M_WAITOK); 2122 /* 2123 * Do not free the first two block in order to avoid overwriting 2124 * any bsd label at the front of the partition 2125 */ 2126 blist_free(sp->sw_blist, 2, nblks - 2); 2127 2128 dvbase = 0; 2129 mtx_lock(&sw_dev_mtx); 2130 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2131 if (tsp->sw_end >= dvbase) { 2132 /* 2133 * We put one uncovered page between the devices 2134 * in order to definitively prevent any cross-device 2135 * I/O requests 2136 */ 2137 dvbase = tsp->sw_end + 1; 2138 } 2139 } 2140 sp->sw_first = dvbase; 2141 sp->sw_end = dvbase + nblks; 2142 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2143 nswapdev++; 2144 swap_pager_avail += nblks - 2; 2145 swap_total += (vm_ooffset_t)nblks * PAGE_SIZE; 2146 swapon_check_swzone(swap_total / PAGE_SIZE); 2147 swp_sizecheck(); 2148 mtx_unlock(&sw_dev_mtx); 2149 EVENTHANDLER_INVOKE(swapon, sp); 2150 } 2151 2152 /* 2153 * SYSCALL: swapoff(devname) 2154 * 2155 * Disable swapping on the given device. 2156 * 2157 * XXX: Badly designed system call: it should use a device index 2158 * rather than filename as specification. We keep sw_vp around 2159 * only to make this work. 2160 */ 2161 #ifndef _SYS_SYSPROTO_H_ 2162 struct swapoff_args { 2163 char *name; 2164 }; 2165 #endif 2166 2167 /* 2168 * MPSAFE 2169 */ 2170 /* ARGSUSED */ 2171 int 2172 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2173 { 2174 struct vnode *vp; 2175 struct nameidata nd; 2176 struct swdevt *sp; 2177 int error; 2178 2179 error = priv_check(td, PRIV_SWAPOFF); 2180 if (error) 2181 return (error); 2182 2183 sx_xlock(&swdev_syscall_lock); 2184 2185 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2186 td); 2187 error = namei(&nd); 2188 if (error) 2189 goto done; 2190 NDFREE(&nd, NDF_ONLY_PNBUF); 2191 vp = nd.ni_vp; 2192 2193 mtx_lock(&sw_dev_mtx); 2194 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2195 if (sp->sw_vp == vp) 2196 break; 2197 } 2198 mtx_unlock(&sw_dev_mtx); 2199 if (sp == NULL) { 2200 error = EINVAL; 2201 goto done; 2202 } 2203 error = swapoff_one(sp, td->td_ucred); 2204 done: 2205 sx_xunlock(&swdev_syscall_lock); 2206 return (error); 2207 } 2208 2209 static int 2210 swapoff_one(struct swdevt *sp, struct ucred *cred) 2211 { 2212 u_long nblks; 2213 #ifdef MAC 2214 int error; 2215 #endif 2216 2217 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2218 #ifdef MAC 2219 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2220 error = mac_system_check_swapoff(cred, sp->sw_vp); 2221 (void) VOP_UNLOCK(sp->sw_vp, 0); 2222 if (error != 0) 2223 return (error); 2224 #endif 2225 nblks = sp->sw_nblks; 2226 2227 /* 2228 * We can turn off this swap device safely only if the 2229 * available virtual memory in the system will fit the amount 2230 * of data we will have to page back in, plus an epsilon so 2231 * the system doesn't become critically low on swap space. 2232 */ 2233 if (vm_cnt.v_free_count + swap_pager_avail < nblks + nswap_lowat) 2234 return (ENOMEM); 2235 2236 /* 2237 * Prevent further allocations on this device. 2238 */ 2239 mtx_lock(&sw_dev_mtx); 2240 sp->sw_flags |= SW_CLOSING; 2241 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2242 swap_total -= (vm_ooffset_t)nblks * PAGE_SIZE; 2243 mtx_unlock(&sw_dev_mtx); 2244 2245 /* 2246 * Page in the contents of the device and close it. 2247 */ 2248 swap_pager_swapoff(sp); 2249 2250 sp->sw_close(curthread, sp); 2251 mtx_lock(&sw_dev_mtx); 2252 sp->sw_id = NULL; 2253 TAILQ_REMOVE(&swtailq, sp, sw_list); 2254 nswapdev--; 2255 if (nswapdev == 0) { 2256 swap_pager_full = 2; 2257 swap_pager_almost_full = 1; 2258 } 2259 if (swdevhd == sp) 2260 swdevhd = NULL; 2261 mtx_unlock(&sw_dev_mtx); 2262 blist_destroy(sp->sw_blist); 2263 free(sp, M_VMPGDATA); 2264 return (0); 2265 } 2266 2267 void 2268 swapoff_all(void) 2269 { 2270 struct swdevt *sp, *spt; 2271 const char *devname; 2272 int error; 2273 2274 sx_xlock(&swdev_syscall_lock); 2275 2276 mtx_lock(&sw_dev_mtx); 2277 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2278 mtx_unlock(&sw_dev_mtx); 2279 if (vn_isdisk(sp->sw_vp, NULL)) 2280 devname = devtoname(sp->sw_vp->v_rdev); 2281 else 2282 devname = "[file]"; 2283 error = swapoff_one(sp, thread0.td_ucred); 2284 if (error != 0) { 2285 printf("Cannot remove swap device %s (error=%d), " 2286 "skipping.\n", devname, error); 2287 } else if (bootverbose) { 2288 printf("Swap device %s removed.\n", devname); 2289 } 2290 mtx_lock(&sw_dev_mtx); 2291 } 2292 mtx_unlock(&sw_dev_mtx); 2293 2294 sx_xunlock(&swdev_syscall_lock); 2295 } 2296 2297 void 2298 swap_pager_status(int *total, int *used) 2299 { 2300 struct swdevt *sp; 2301 2302 *total = 0; 2303 *used = 0; 2304 mtx_lock(&sw_dev_mtx); 2305 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2306 *total += sp->sw_nblks; 2307 *used += sp->sw_used; 2308 } 2309 mtx_unlock(&sw_dev_mtx); 2310 } 2311 2312 int 2313 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2314 { 2315 struct swdevt *sp; 2316 const char *tmp_devname; 2317 int error, n; 2318 2319 n = 0; 2320 error = ENOENT; 2321 mtx_lock(&sw_dev_mtx); 2322 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2323 if (n != name) { 2324 n++; 2325 continue; 2326 } 2327 xs->xsw_version = XSWDEV_VERSION; 2328 xs->xsw_dev = sp->sw_dev; 2329 xs->xsw_flags = sp->sw_flags; 2330 xs->xsw_nblks = sp->sw_nblks; 2331 xs->xsw_used = sp->sw_used; 2332 if (devname != NULL) { 2333 if (vn_isdisk(sp->sw_vp, NULL)) 2334 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2335 else 2336 tmp_devname = "[file]"; 2337 strncpy(devname, tmp_devname, len); 2338 } 2339 error = 0; 2340 break; 2341 } 2342 mtx_unlock(&sw_dev_mtx); 2343 return (error); 2344 } 2345 2346 #if defined(COMPAT_FREEBSD11) 2347 #define XSWDEV_VERSION_11 1 2348 struct xswdev11 { 2349 u_int xsw_version; 2350 uint32_t xsw_dev; 2351 int xsw_flags; 2352 int xsw_nblks; 2353 int xsw_used; 2354 }; 2355 #endif 2356 2357 static int 2358 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2359 { 2360 struct xswdev xs; 2361 #if defined(COMPAT_FREEBSD11) 2362 struct xswdev11 xs11; 2363 #endif 2364 int error; 2365 2366 if (arg2 != 1) /* name length */ 2367 return (EINVAL); 2368 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2369 if (error != 0) 2370 return (error); 2371 #if defined(COMPAT_FREEBSD11) 2372 if (req->oldlen == sizeof(xs11)) { 2373 xs11.xsw_version = XSWDEV_VERSION_11; 2374 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2375 xs11.xsw_flags = xs.xsw_flags; 2376 xs11.xsw_nblks = xs.xsw_nblks; 2377 xs11.xsw_used = xs.xsw_used; 2378 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2379 } else 2380 #endif 2381 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2382 return (error); 2383 } 2384 2385 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2386 "Number of swap devices"); 2387 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2388 sysctl_vm_swap_info, 2389 "Swap statistics by device"); 2390 2391 /* 2392 * Count the approximate swap usage in pages for a vmspace. The 2393 * shadowed or not yet copied on write swap blocks are not accounted. 2394 * The map must be locked. 2395 */ 2396 long 2397 vmspace_swap_count(struct vmspace *vmspace) 2398 { 2399 vm_map_t map; 2400 vm_map_entry_t cur; 2401 vm_object_t object; 2402 struct swblk *sb; 2403 vm_pindex_t e, pi; 2404 long count; 2405 int i; 2406 2407 map = &vmspace->vm_map; 2408 count = 0; 2409 2410 for (cur = map->header.next; cur != &map->header; cur = cur->next) { 2411 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 2412 continue; 2413 object = cur->object.vm_object; 2414 if (object == NULL || object->type != OBJT_SWAP) 2415 continue; 2416 VM_OBJECT_RLOCK(object); 2417 if (object->type != OBJT_SWAP) 2418 goto unlock; 2419 pi = OFF_TO_IDX(cur->offset); 2420 e = pi + OFF_TO_IDX(cur->end - cur->start); 2421 for (;; pi = sb->p + SWAP_META_PAGES) { 2422 sb = SWAP_PCTRIE_LOOKUP_GE( 2423 &object->un_pager.swp.swp_blks, pi); 2424 if (sb == NULL || sb->p >= e) 2425 break; 2426 for (i = 0; i < SWAP_META_PAGES; i++) { 2427 if (sb->p + i < e && 2428 sb->d[i] != SWAPBLK_NONE) 2429 count++; 2430 } 2431 } 2432 unlock: 2433 VM_OBJECT_RUNLOCK(object); 2434 } 2435 return (count); 2436 } 2437 2438 /* 2439 * GEOM backend 2440 * 2441 * Swapping onto disk devices. 2442 * 2443 */ 2444 2445 static g_orphan_t swapgeom_orphan; 2446 2447 static struct g_class g_swap_class = { 2448 .name = "SWAP", 2449 .version = G_VERSION, 2450 .orphan = swapgeom_orphan, 2451 }; 2452 2453 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2454 2455 2456 static void 2457 swapgeom_close_ev(void *arg, int flags) 2458 { 2459 struct g_consumer *cp; 2460 2461 cp = arg; 2462 g_access(cp, -1, -1, 0); 2463 g_detach(cp); 2464 g_destroy_consumer(cp); 2465 } 2466 2467 /* 2468 * Add a reference to the g_consumer for an inflight transaction. 2469 */ 2470 static void 2471 swapgeom_acquire(struct g_consumer *cp) 2472 { 2473 2474 mtx_assert(&sw_dev_mtx, MA_OWNED); 2475 cp->index++; 2476 } 2477 2478 /* 2479 * Remove a reference from the g_consumer. Post a close event if all 2480 * references go away, since the function might be called from the 2481 * biodone context. 2482 */ 2483 static void 2484 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2485 { 2486 2487 mtx_assert(&sw_dev_mtx, MA_OWNED); 2488 cp->index--; 2489 if (cp->index == 0) { 2490 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2491 sp->sw_id = NULL; 2492 } 2493 } 2494 2495 static void 2496 swapgeom_done(struct bio *bp2) 2497 { 2498 struct swdevt *sp; 2499 struct buf *bp; 2500 struct g_consumer *cp; 2501 2502 bp = bp2->bio_caller2; 2503 cp = bp2->bio_from; 2504 bp->b_ioflags = bp2->bio_flags; 2505 if (bp2->bio_error) 2506 bp->b_ioflags |= BIO_ERROR; 2507 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2508 bp->b_error = bp2->bio_error; 2509 bufdone(bp); 2510 sp = bp2->bio_caller1; 2511 mtx_lock(&sw_dev_mtx); 2512 swapgeom_release(cp, sp); 2513 mtx_unlock(&sw_dev_mtx); 2514 g_destroy_bio(bp2); 2515 } 2516 2517 static void 2518 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2519 { 2520 struct bio *bio; 2521 struct g_consumer *cp; 2522 2523 mtx_lock(&sw_dev_mtx); 2524 cp = sp->sw_id; 2525 if (cp == NULL) { 2526 mtx_unlock(&sw_dev_mtx); 2527 bp->b_error = ENXIO; 2528 bp->b_ioflags |= BIO_ERROR; 2529 bufdone(bp); 2530 return; 2531 } 2532 swapgeom_acquire(cp); 2533 mtx_unlock(&sw_dev_mtx); 2534 if (bp->b_iocmd == BIO_WRITE) 2535 bio = g_new_bio(); 2536 else 2537 bio = g_alloc_bio(); 2538 if (bio == NULL) { 2539 mtx_lock(&sw_dev_mtx); 2540 swapgeom_release(cp, sp); 2541 mtx_unlock(&sw_dev_mtx); 2542 bp->b_error = ENOMEM; 2543 bp->b_ioflags |= BIO_ERROR; 2544 bufdone(bp); 2545 return; 2546 } 2547 2548 bio->bio_caller1 = sp; 2549 bio->bio_caller2 = bp; 2550 bio->bio_cmd = bp->b_iocmd; 2551 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2552 bio->bio_length = bp->b_bcount; 2553 bio->bio_done = swapgeom_done; 2554 if (!buf_mapped(bp)) { 2555 bio->bio_ma = bp->b_pages; 2556 bio->bio_data = unmapped_buf; 2557 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2558 bio->bio_ma_n = bp->b_npages; 2559 bio->bio_flags |= BIO_UNMAPPED; 2560 } else { 2561 bio->bio_data = bp->b_data; 2562 bio->bio_ma = NULL; 2563 } 2564 g_io_request(bio, cp); 2565 return; 2566 } 2567 2568 static void 2569 swapgeom_orphan(struct g_consumer *cp) 2570 { 2571 struct swdevt *sp; 2572 int destroy; 2573 2574 mtx_lock(&sw_dev_mtx); 2575 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2576 if (sp->sw_id == cp) { 2577 sp->sw_flags |= SW_CLOSING; 2578 break; 2579 } 2580 } 2581 /* 2582 * Drop reference we were created with. Do directly since we're in a 2583 * special context where we don't have to queue the call to 2584 * swapgeom_close_ev(). 2585 */ 2586 cp->index--; 2587 destroy = ((sp != NULL) && (cp->index == 0)); 2588 if (destroy) 2589 sp->sw_id = NULL; 2590 mtx_unlock(&sw_dev_mtx); 2591 if (destroy) 2592 swapgeom_close_ev(cp, 0); 2593 } 2594 2595 static void 2596 swapgeom_close(struct thread *td, struct swdevt *sw) 2597 { 2598 struct g_consumer *cp; 2599 2600 mtx_lock(&sw_dev_mtx); 2601 cp = sw->sw_id; 2602 sw->sw_id = NULL; 2603 mtx_unlock(&sw_dev_mtx); 2604 2605 /* 2606 * swapgeom_close() may be called from the biodone context, 2607 * where we cannot perform topology changes. Delegate the 2608 * work to the events thread. 2609 */ 2610 if (cp != NULL) 2611 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2612 } 2613 2614 static int 2615 swapongeom_locked(struct cdev *dev, struct vnode *vp) 2616 { 2617 struct g_provider *pp; 2618 struct g_consumer *cp; 2619 static struct g_geom *gp; 2620 struct swdevt *sp; 2621 u_long nblks; 2622 int error; 2623 2624 pp = g_dev_getprovider(dev); 2625 if (pp == NULL) 2626 return (ENODEV); 2627 mtx_lock(&sw_dev_mtx); 2628 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2629 cp = sp->sw_id; 2630 if (cp != NULL && cp->provider == pp) { 2631 mtx_unlock(&sw_dev_mtx); 2632 return (EBUSY); 2633 } 2634 } 2635 mtx_unlock(&sw_dev_mtx); 2636 if (gp == NULL) 2637 gp = g_new_geomf(&g_swap_class, "swap"); 2638 cp = g_new_consumer(gp); 2639 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2640 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2641 g_attach(cp, pp); 2642 /* 2643 * XXX: Every time you think you can improve the margin for 2644 * footshooting, somebody depends on the ability to do so: 2645 * savecore(8) wants to write to our swapdev so we cannot 2646 * set an exclusive count :-( 2647 */ 2648 error = g_access(cp, 1, 1, 0); 2649 if (error != 0) { 2650 g_detach(cp); 2651 g_destroy_consumer(cp); 2652 return (error); 2653 } 2654 nblks = pp->mediasize / DEV_BSIZE; 2655 swaponsomething(vp, cp, nblks, swapgeom_strategy, 2656 swapgeom_close, dev2udev(dev), 2657 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2658 return (0); 2659 } 2660 2661 static int 2662 swapongeom(struct vnode *vp) 2663 { 2664 int error; 2665 2666 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2667 if (vp->v_type != VCHR || (vp->v_iflag & VI_DOOMED) != 0) { 2668 error = ENOENT; 2669 } else { 2670 g_topology_lock(); 2671 error = swapongeom_locked(vp->v_rdev, vp); 2672 g_topology_unlock(); 2673 } 2674 VOP_UNLOCK(vp, 0); 2675 return (error); 2676 } 2677 2678 /* 2679 * VNODE backend 2680 * 2681 * This is used mainly for network filesystem (read: probably only tested 2682 * with NFS) swapfiles. 2683 * 2684 */ 2685 2686 static void 2687 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2688 { 2689 struct vnode *vp2; 2690 2691 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2692 2693 vp2 = sp->sw_id; 2694 vhold(vp2); 2695 if (bp->b_iocmd == BIO_WRITE) { 2696 if (bp->b_bufobj) 2697 bufobj_wdrop(bp->b_bufobj); 2698 bufobj_wref(&vp2->v_bufobj); 2699 } 2700 if (bp->b_bufobj != &vp2->v_bufobj) 2701 bp->b_bufobj = &vp2->v_bufobj; 2702 bp->b_vp = vp2; 2703 bp->b_iooffset = dbtob(bp->b_blkno); 2704 bstrategy(bp); 2705 return; 2706 } 2707 2708 static void 2709 swapdev_close(struct thread *td, struct swdevt *sp) 2710 { 2711 2712 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2713 vrele(sp->sw_vp); 2714 } 2715 2716 2717 static int 2718 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2719 { 2720 struct swdevt *sp; 2721 int error; 2722 2723 if (nblks == 0) 2724 return (ENXIO); 2725 mtx_lock(&sw_dev_mtx); 2726 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2727 if (sp->sw_id == vp) { 2728 mtx_unlock(&sw_dev_mtx); 2729 return (EBUSY); 2730 } 2731 } 2732 mtx_unlock(&sw_dev_mtx); 2733 2734 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2735 #ifdef MAC 2736 error = mac_system_check_swapon(td->td_ucred, vp); 2737 if (error == 0) 2738 #endif 2739 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 2740 (void) VOP_UNLOCK(vp, 0); 2741 if (error) 2742 return (error); 2743 2744 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 2745 NODEV, 0); 2746 return (0); 2747 } 2748 2749 static int 2750 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 2751 { 2752 int error, new, n; 2753 2754 new = nsw_wcount_async_max; 2755 error = sysctl_handle_int(oidp, &new, 0, req); 2756 if (error != 0 || req->newptr == NULL) 2757 return (error); 2758 2759 if (new > nswbuf / 2 || new < 1) 2760 return (EINVAL); 2761 2762 mtx_lock(&pbuf_mtx); 2763 while (nsw_wcount_async_max != new) { 2764 /* 2765 * Adjust difference. If the current async count is too low, 2766 * we will need to sqeeze our update slowly in. Sleep with a 2767 * higher priority than getpbuf() to finish faster. 2768 */ 2769 n = new - nsw_wcount_async_max; 2770 if (nsw_wcount_async + n >= 0) { 2771 nsw_wcount_async += n; 2772 nsw_wcount_async_max += n; 2773 wakeup(&nsw_wcount_async); 2774 } else { 2775 nsw_wcount_async_max -= nsw_wcount_async; 2776 nsw_wcount_async = 0; 2777 msleep(&nsw_wcount_async, &pbuf_mtx, PSWP, 2778 "swpsysctl", 0); 2779 } 2780 } 2781 mtx_unlock(&pbuf_mtx); 2782 2783 return (0); 2784 } 2785