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: stable/10/sys/vm/swap_pager.c 320557 2017-07-01 22:21:11Z alc $"); 71 72#include "opt_swap.h" 73#include "opt_vm.h" 74 75#include <sys/param.h> 76#include <sys/systm.h> 77#include <sys/conf.h> 78#include <sys/kernel.h> 79#include <sys/priv.h> 80#include <sys/proc.h> 81#include <sys/bio.h> 82#include <sys/buf.h> 83#include <sys/disk.h> 84#include <sys/fcntl.h> 85#include <sys/mount.h> 86#include <sys/namei.h> 87#include <sys/vnode.h> 88#include <sys/malloc.h> 89#include <sys/racct.h> 90#include <sys/resource.h> 91#include <sys/resourcevar.h> 92#include <sys/rwlock.h> 93#include <sys/sysctl.h> 94#include <sys/sysproto.h> 95#include <sys/blist.h> 96#include <sys/lock.h> 97#include <sys/sx.h> 98#include <sys/vmmeter.h> 99 100#include <security/mac/mac_framework.h> 101 102#include <vm/vm.h> 103#include <vm/pmap.h> 104#include <vm/vm_map.h> 105#include <vm/vm_kern.h> 106#include <vm/vm_object.h> 107#include <vm/vm_page.h> 108#include <vm/vm_pager.h> 109#include <vm/vm_pageout.h> 110#include <vm/vm_param.h> 111#include <vm/swap_pager.h> 112#include <vm/vm_extern.h> 113#include <vm/uma.h> 114 115#include <geom/geom.h> 116 117/* 118 * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64. 119 * The 64-page limit is due to the radix code (kern/subr_blist.c). 120 */ 121#ifndef MAX_PAGEOUT_CLUSTER 122#define MAX_PAGEOUT_CLUSTER 16 123#endif 124 125#if !defined(SWB_NPAGES) 126#define SWB_NPAGES MAX_PAGEOUT_CLUSTER 127#endif 128 129/* 130 * The swblock structure maps an object and a small, fixed-size range 131 * of page indices to disk addresses within a swap area. 132 * The collection of these mappings is implemented as a hash table. 133 * Unused disk addresses within a swap area are allocated and managed 134 * using a blist. 135 */ 136#define SWAP_META_PAGES (SWB_NPAGES * 2) 137#define SWAP_META_MASK (SWAP_META_PAGES - 1) 138 139struct swblock { 140 struct swblock *swb_hnext; 141 vm_object_t swb_object; 142 vm_pindex_t swb_index; 143 int swb_count; 144 daddr_t swb_pages[SWAP_META_PAGES]; 145}; 146 147static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); 148static struct mtx sw_dev_mtx; 149static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 150static struct swdevt *swdevhd; /* Allocate from here next */ 151static int nswapdev; /* Number of swap devices */ 152int swap_pager_avail; 153static int swdev_syscall_active = 0; /* serialize swap(on|off) */ 154 155static vm_ooffset_t swap_total; 156SYSCTL_QUAD(_vm, OID_AUTO, swap_total, CTLFLAG_RD, &swap_total, 0, 157 "Total amount of available swap storage."); 158static vm_ooffset_t swap_reserved; 159SYSCTL_QUAD(_vm, OID_AUTO, swap_reserved, CTLFLAG_RD, &swap_reserved, 0, 160 "Amount of swap storage needed to back all allocated anonymous memory."); 161static int overcommit = 0; 162SYSCTL_INT(_vm, OID_AUTO, overcommit, CTLFLAG_RW, &overcommit, 0, 163 "Configure virtual memory overcommit behavior. See tuning(7) " 164 "for details."); 165static unsigned long swzone; 166SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 167 "Actual size of swap metadata zone"); 168static unsigned long swap_maxpages; 169SYSCTL_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 177int 178swap_reserve(vm_ooffset_t incr) 179{ 180 181 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 182} 183 184int 185swap_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 = cnt.v_page_count - cnt.v_free_reserved - 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 PROC_LOCK(curproc); 226 UIDINFO_VMSIZE_LOCK(uip); 227 if ((overcommit & SWAP_RESERVE_RLIMIT_ON) != 0 && 228 uip->ui_vmsize + incr > lim_cur(curproc, RLIMIT_SWAP) && 229 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT)) 230 res = 0; 231 else 232 uip->ui_vmsize += incr; 233 UIDINFO_VMSIZE_UNLOCK(uip); 234 PROC_UNLOCK(curproc); 235 if (!res) { 236 mtx_lock(&sw_dev_mtx); 237 swap_reserved -= incr; 238 mtx_unlock(&sw_dev_mtx); 239 } 240 } 241 if (!res && ppsratecheck(&lastfail, &curfail, 1)) { 242 printf("uid %d, pid %d: swap reservation for %jd bytes failed\n", 243 uip->ui_uid, curproc->p_pid, incr); 244 } 245 246#ifdef RACCT 247 if (!res) { 248 PROC_LOCK(curproc); 249 racct_sub(curproc, RACCT_SWAP, incr); 250 PROC_UNLOCK(curproc); 251 } 252#endif 253 254 return (res); 255} 256 257void 258swap_reserve_force(vm_ooffset_t incr) 259{ 260 struct uidinfo *uip; 261 262 mtx_lock(&sw_dev_mtx); 263 swap_reserved += incr; 264 mtx_unlock(&sw_dev_mtx); 265 266#ifdef RACCT 267 PROC_LOCK(curproc); 268 racct_add_force(curproc, RACCT_SWAP, incr); 269 PROC_UNLOCK(curproc); 270#endif 271 272 uip = curthread->td_ucred->cr_ruidinfo; 273 PROC_LOCK(curproc); 274 UIDINFO_VMSIZE_LOCK(uip); 275 uip->ui_vmsize += incr; 276 UIDINFO_VMSIZE_UNLOCK(uip); 277 PROC_UNLOCK(curproc); 278} 279 280void 281swap_release(vm_ooffset_t decr) 282{ 283 struct ucred *cred; 284 285 PROC_LOCK(curproc); 286 cred = curthread->td_ucred; 287 swap_release_by_cred(decr, cred); 288 PROC_UNLOCK(curproc); 289} 290 291void 292swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 293{ 294 struct uidinfo *uip; 295 296 uip = cred->cr_ruidinfo; 297 298 if (decr & PAGE_MASK) 299 panic("swap_release: & PAGE_MASK"); 300 301 mtx_lock(&sw_dev_mtx); 302 if (swap_reserved < decr) 303 panic("swap_reserved < decr"); 304 swap_reserved -= decr; 305 mtx_unlock(&sw_dev_mtx); 306 307 UIDINFO_VMSIZE_LOCK(uip); 308 if (uip->ui_vmsize < decr) 309 printf("negative vmsize for uid = %d\n", uip->ui_uid); 310 uip->ui_vmsize -= decr; 311 UIDINFO_VMSIZE_UNLOCK(uip); 312 313 racct_sub_cred(cred, RACCT_SWAP, decr); 314} 315 316static void swapdev_strategy(struct buf *, struct swdevt *sw); 317 318#define SWM_FREE 0x02 /* free, period */ 319#define SWM_POP 0x04 /* pop out */ 320 321int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 322static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 323static int nsw_rcount; /* free read buffers */ 324static int nsw_wcount_sync; /* limit write buffers / synchronous */ 325static int nsw_wcount_async; /* limit write buffers / asynchronous */ 326static int nsw_wcount_async_max;/* assigned maximum */ 327static int nsw_cluster_max; /* maximum VOP I/O allowed */ 328 329static struct swblock **swhash; 330static int swhash_mask; 331static struct mtx swhash_mtx; 332 333static int swap_async_max = 4; /* maximum in-progress async I/O's */ 334static struct sx sw_alloc_sx; 335 336 337SYSCTL_INT(_vm, OID_AUTO, swap_async_max, 338 CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops"); 339 340/* 341 * "named" and "unnamed" anon region objects. Try to reduce the overhead 342 * of searching a named list by hashing it just a little. 343 */ 344 345#define NOBJLISTS 8 346 347#define NOBJLIST(handle) \ 348 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 349 350static struct mtx sw_alloc_mtx; /* protect list manipulation */ 351static struct pagerlst swap_pager_object_list[NOBJLISTS]; 352static uma_zone_t swap_zone; 353 354/* 355 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 356 * calls hooked from other parts of the VM system and do not appear here. 357 * (see vm/swap_pager.h). 358 */ 359static vm_object_t 360 swap_pager_alloc(void *handle, vm_ooffset_t size, 361 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 362static void swap_pager_dealloc(vm_object_t object); 363static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int); 364static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 365static boolean_t 366 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 367static void swap_pager_init(void); 368static void swap_pager_unswapped(vm_page_t); 369static void swap_pager_swapoff(struct swdevt *sp); 370 371struct pagerops swappagerops = { 372 .pgo_init = swap_pager_init, /* early system initialization of pager */ 373 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 374 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 375 .pgo_getpages = swap_pager_getpages, /* pagein */ 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 */ 385static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 386static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 387 388SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 389 "Maximum size of a swap block in pages"); 390 391static void swp_sizecheck(void); 392static void swp_pager_async_iodone(struct buf *bp); 393static int swapongeom(struct thread *, struct vnode *); 394static int swaponvp(struct thread *, struct vnode *, u_long); 395static int swapoff_one(struct swdevt *sp, struct ucred *cred); 396 397/* 398 * Swap bitmap functions 399 */ 400static void swp_pager_freeswapspace(daddr_t blk, int npages); 401static daddr_t swp_pager_getswapspace(int npages); 402 403/* 404 * Metadata functions 405 */ 406static struct swblock **swp_pager_hash(vm_object_t object, vm_pindex_t index); 407static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 408static void swp_pager_meta_free(vm_object_t, vm_pindex_t, daddr_t); 409static void swp_pager_meta_free_all(vm_object_t); 410static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 411 412static void 413swp_pager_free_nrpage(vm_page_t m) 414{ 415 416 vm_page_lock(m); 417 if (m->wire_count == 0) 418 vm_page_free(m); 419 vm_page_unlock(m); 420} 421 422/* 423 * SWP_SIZECHECK() - update swap_pager_full indication 424 * 425 * update the swap_pager_almost_full indication and warn when we are 426 * about to run out of swap space, using lowat/hiwat hysteresis. 427 * 428 * Clear swap_pager_full ( task killing ) indication when lowat is met. 429 * 430 * No restrictions on call 431 * This routine may not block. 432 */ 433static void 434swp_sizecheck(void) 435{ 436 437 if (swap_pager_avail < nswap_lowat) { 438 if (swap_pager_almost_full == 0) { 439 printf("swap_pager: out of swap space\n"); 440 swap_pager_almost_full = 1; 441 } 442 } else { 443 swap_pager_full = 0; 444 if (swap_pager_avail > nswap_hiwat) 445 swap_pager_almost_full = 0; 446 } 447} 448 449/* 450 * SWP_PAGER_HASH() - hash swap meta data 451 * 452 * This is an helper function which hashes the swapblk given 453 * the object and page index. It returns a pointer to a pointer 454 * to the object, or a pointer to a NULL pointer if it could not 455 * find a swapblk. 456 */ 457static struct swblock ** 458swp_pager_hash(vm_object_t object, vm_pindex_t index) 459{ 460 struct swblock **pswap; 461 struct swblock *swap; 462 463 index &= ~(vm_pindex_t)SWAP_META_MASK; 464 pswap = &swhash[(index ^ (int)(intptr_t)object) & swhash_mask]; 465 while ((swap = *pswap) != NULL) { 466 if (swap->swb_object == object && 467 swap->swb_index == index 468 ) { 469 break; 470 } 471 pswap = &swap->swb_hnext; 472 } 473 return (pswap); 474} 475 476/* 477 * SWAP_PAGER_INIT() - initialize the swap pager! 478 * 479 * Expected to be started from system init. NOTE: This code is run 480 * before much else so be careful what you depend on. Most of the VM 481 * system has yet to be initialized at this point. 482 */ 483static void 484swap_pager_init(void) 485{ 486 /* 487 * Initialize object lists 488 */ 489 int i; 490 491 for (i = 0; i < NOBJLISTS; ++i) 492 TAILQ_INIT(&swap_pager_object_list[i]); 493 mtx_init(&sw_alloc_mtx, "swap_pager list", NULL, MTX_DEF); 494 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 495 sx_init(&sw_alloc_sx, "swspsx"); 496} 497 498/* 499 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 500 * 501 * Expected to be started from pageout process once, prior to entering 502 * its main loop. 503 */ 504void 505swap_pager_swap_init(void) 506{ 507 unsigned long n, n2; 508 509 /* 510 * Number of in-transit swap bp operations. Don't 511 * exhaust the pbufs completely. Make sure we 512 * initialize workable values (0 will work for hysteresis 513 * but it isn't very efficient). 514 * 515 * The nsw_cluster_max is constrained by the bp->b_pages[] 516 * array (MAXPHYS/PAGE_SIZE) and our locally defined 517 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 518 * constrained by the swap device interleave stripe size. 519 * 520 * Currently we hardwire nsw_wcount_async to 4. This limit is 521 * designed to prevent other I/O from having high latencies due to 522 * our pageout I/O. The value 4 works well for one or two active swap 523 * devices but is probably a little low if you have more. Even so, 524 * a higher value would probably generate only a limited improvement 525 * with three or four active swap devices since the system does not 526 * typically have to pageout at extreme bandwidths. We will want 527 * at least 2 per swap devices, and 4 is a pretty good value if you 528 * have one NFS swap device due to the command/ack latency over NFS. 529 * So it all works out pretty well. 530 */ 531 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER); 532 533 mtx_lock(&pbuf_mtx); 534 nsw_rcount = (nswbuf + 1) / 2; 535 nsw_wcount_sync = (nswbuf + 3) / 4; 536 nsw_wcount_async = 4; 537 nsw_wcount_async_max = nsw_wcount_async; 538 mtx_unlock(&pbuf_mtx); 539 540 /* 541 * Initialize our zone. Right now I'm just guessing on the number 542 * we need based on the number of pages in the system. Each swblock 543 * can hold 32 pages, so this is probably overkill. This reservation 544 * is typically limited to around 32MB by default. 545 */ 546 n = cnt.v_page_count / 2; 547 if (maxswzone && n > maxswzone / sizeof(struct swblock)) 548 n = maxswzone / sizeof(struct swblock); 549 n2 = n; 550 swap_zone = uma_zcreate("SWAPMETA", sizeof(struct swblock), NULL, NULL, 551 NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE | UMA_ZONE_VM); 552 if (swap_zone == NULL) 553 panic("failed to create swap_zone."); 554 do { 555 if (uma_zone_reserve_kva(swap_zone, n)) 556 break; 557 /* 558 * if the allocation failed, try a zone two thirds the 559 * size of the previous attempt. 560 */ 561 n -= ((n + 2) / 3); 562 } while (n > 0); 563 if (n2 != n) 564 printf("Swap zone entries reduced from %lu to %lu.\n", n2, n); 565 swap_maxpages = n * SWAP_META_PAGES; 566 swzone = n * sizeof(struct swblock); 567 n2 = n; 568 569 /* 570 * Initialize our meta-data hash table. The swapper does not need to 571 * be quite as efficient as the VM system, so we do not use an 572 * oversized hash table. 573 * 574 * n: size of hash table, must be power of 2 575 * swhash_mask: hash table index mask 576 */ 577 for (n = 1; n < n2 / 8; n *= 2) 578 ; 579 swhash = malloc(sizeof(struct swblock *) * n, M_VMPGDATA, M_WAITOK | M_ZERO); 580 swhash_mask = n - 1; 581 mtx_init(&swhash_mtx, "swap_pager swhash", NULL, MTX_DEF); 582} 583 584/* 585 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 586 * its metadata structures. 587 * 588 * This routine is called from the mmap and fork code to create a new 589 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object 590 * and then converting it with swp_pager_meta_build(). 591 * 592 * This routine may block in vm_object_allocate() and create a named 593 * object lookup race, so we must interlock. 594 * 595 * MPSAFE 596 */ 597static vm_object_t 598swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 599 vm_ooffset_t offset, struct ucred *cred) 600{ 601 vm_object_t object; 602 vm_pindex_t pindex; 603 604 pindex = OFF_TO_IDX(offset + PAGE_MASK + size); 605 if (handle) { 606 mtx_lock(&Giant); 607 /* 608 * Reference existing named region or allocate new one. There 609 * should not be a race here against swp_pager_meta_build() 610 * as called from vm_page_remove() in regards to the lookup 611 * of the handle. 612 */ 613 sx_xlock(&sw_alloc_sx); 614 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 615 if (object == NULL) { 616 if (cred != NULL) { 617 if (!swap_reserve_by_cred(size, cred)) { 618 sx_xunlock(&sw_alloc_sx); 619 mtx_unlock(&Giant); 620 return (NULL); 621 } 622 crhold(cred); 623 } 624 object = vm_object_allocate(OBJT_DEFAULT, pindex); 625 VM_OBJECT_WLOCK(object); 626 object->handle = handle; 627 if (cred != NULL) { 628 object->cred = cred; 629 object->charge = size; 630 } 631 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 632 VM_OBJECT_WUNLOCK(object); 633 } 634 sx_xunlock(&sw_alloc_sx); 635 mtx_unlock(&Giant); 636 } else { 637 if (cred != NULL) { 638 if (!swap_reserve_by_cred(size, cred)) 639 return (NULL); 640 crhold(cred); 641 } 642 object = vm_object_allocate(OBJT_DEFAULT, pindex); 643 VM_OBJECT_WLOCK(object); 644 if (cred != NULL) { 645 object->cred = cred; 646 object->charge = size; 647 } 648 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 649 VM_OBJECT_WUNLOCK(object); 650 } 651 return (object); 652} 653 654/* 655 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 656 * 657 * The swap backing for the object is destroyed. The code is 658 * designed such that we can reinstantiate it later, but this 659 * routine is typically called only when the entire object is 660 * about to be destroyed. 661 * 662 * The object must be locked. 663 */ 664static void 665swap_pager_dealloc(vm_object_t object) 666{ 667 668 /* 669 * Remove from list right away so lookups will fail if we block for 670 * pageout completion. 671 */ 672 if (object->handle != NULL) { 673 mtx_lock(&sw_alloc_mtx); 674 TAILQ_REMOVE(NOBJLIST(object->handle), object, pager_object_list); 675 mtx_unlock(&sw_alloc_mtx); 676 } 677 678 VM_OBJECT_ASSERT_WLOCKED(object); 679 vm_object_pip_wait(object, "swpdea"); 680 681 /* 682 * Free all remaining metadata. We only bother to free it from 683 * the swap meta data. We do not attempt to free swapblk's still 684 * associated with vm_page_t's for this object. We do not care 685 * if paging is still in progress on some objects. 686 */ 687 swp_pager_meta_free_all(object); 688 object->handle = NULL; 689 object->type = OBJT_DEAD; 690} 691 692/************************************************************************ 693 * SWAP PAGER BITMAP ROUTINES * 694 ************************************************************************/ 695 696/* 697 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 698 * 699 * Allocate swap for the requested number of pages. The starting 700 * swap block number (a page index) is returned or SWAPBLK_NONE 701 * if the allocation failed. 702 * 703 * Also has the side effect of advising that somebody made a mistake 704 * when they configured swap and didn't configure enough. 705 * 706 * This routine may not sleep. 707 * 708 * We allocate in round-robin fashion from the configured devices. 709 */ 710static daddr_t 711swp_pager_getswapspace(int npages) 712{ 713 daddr_t blk; 714 struct swdevt *sp; 715 int i; 716 717 blk = SWAPBLK_NONE; 718 mtx_lock(&sw_dev_mtx); 719 sp = swdevhd; 720 for (i = 0; i < nswapdev; i++) { 721 if (sp == NULL) 722 sp = TAILQ_FIRST(&swtailq); 723 if (!(sp->sw_flags & SW_CLOSING)) { 724 blk = blist_alloc(sp->sw_blist, npages); 725 if (blk != SWAPBLK_NONE) { 726 blk += sp->sw_first; 727 sp->sw_used += npages; 728 swap_pager_avail -= npages; 729 swp_sizecheck(); 730 swdevhd = TAILQ_NEXT(sp, sw_list); 731 goto done; 732 } 733 } 734 sp = TAILQ_NEXT(sp, sw_list); 735 } 736 if (swap_pager_full != 2) { 737 printf("swap_pager_getswapspace(%d): failed\n", npages); 738 swap_pager_full = 2; 739 swap_pager_almost_full = 1; 740 } 741 swdevhd = NULL; 742done: 743 mtx_unlock(&sw_dev_mtx); 744 return (blk); 745} 746 747static int 748swp_pager_isondev(daddr_t blk, struct swdevt *sp) 749{ 750 751 return (blk >= sp->sw_first && blk < sp->sw_end); 752} 753 754static void 755swp_pager_strategy(struct buf *bp) 756{ 757 struct swdevt *sp; 758 759 mtx_lock(&sw_dev_mtx); 760 TAILQ_FOREACH(sp, &swtailq, sw_list) { 761 if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) { 762 mtx_unlock(&sw_dev_mtx); 763 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 764 unmapped_buf_allowed) { 765 bp->b_kvaalloc = bp->b_data; 766 bp->b_data = unmapped_buf; 767 bp->b_kvabase = unmapped_buf; 768 bp->b_offset = 0; 769 bp->b_flags |= B_UNMAPPED; 770 } else { 771 pmap_qenter((vm_offset_t)bp->b_data, 772 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 773 } 774 sp->sw_strategy(bp, sp); 775 return; 776 } 777 } 778 panic("Swapdev not found"); 779} 780 781 782/* 783 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 784 * 785 * This routine returns the specified swap blocks back to the bitmap. 786 * 787 * This routine may not sleep. 788 */ 789static void 790swp_pager_freeswapspace(daddr_t blk, int npages) 791{ 792 struct swdevt *sp; 793 794 mtx_lock(&sw_dev_mtx); 795 TAILQ_FOREACH(sp, &swtailq, sw_list) { 796 if (blk >= sp->sw_first && blk < sp->sw_end) { 797 sp->sw_used -= npages; 798 /* 799 * If we are attempting to stop swapping on 800 * this device, we don't want to mark any 801 * blocks free lest they be reused. 802 */ 803 if ((sp->sw_flags & SW_CLOSING) == 0) { 804 blist_free(sp->sw_blist, blk - sp->sw_first, 805 npages); 806 swap_pager_avail += npages; 807 swp_sizecheck(); 808 } 809 mtx_unlock(&sw_dev_mtx); 810 return; 811 } 812 } 813 panic("Swapdev not found"); 814} 815 816/* 817 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 818 * range within an object. 819 * 820 * This is a globally accessible routine. 821 * 822 * This routine removes swapblk assignments from swap metadata. 823 * 824 * The external callers of this routine typically have already destroyed 825 * or renamed vm_page_t's associated with this range in the object so 826 * we should be ok. 827 * 828 * The object must be locked. 829 */ 830void 831swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 832{ 833 834 swp_pager_meta_free(object, start, size); 835} 836 837/* 838 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 839 * 840 * Assigns swap blocks to the specified range within the object. The 841 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 842 * 843 * Returns 0 on success, -1 on failure. 844 */ 845int 846swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 847{ 848 int n = 0; 849 daddr_t blk = SWAPBLK_NONE; 850 vm_pindex_t beg = start; /* save start index */ 851 852 VM_OBJECT_WLOCK(object); 853 while (size) { 854 if (n == 0) { 855 n = BLIST_MAX_ALLOC; 856 while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) { 857 n >>= 1; 858 if (n == 0) { 859 swp_pager_meta_free(object, beg, start - beg); 860 VM_OBJECT_WUNLOCK(object); 861 return (-1); 862 } 863 } 864 } 865 swp_pager_meta_build(object, start, blk); 866 --size; 867 ++start; 868 ++blk; 869 --n; 870 } 871 swp_pager_meta_free(object, start, n); 872 VM_OBJECT_WUNLOCK(object); 873 return (0); 874} 875 876/* 877 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 878 * and destroy the source. 879 * 880 * Copy any valid swapblks from the source to the destination. In 881 * cases where both the source and destination have a valid swapblk, 882 * we keep the destination's. 883 * 884 * This routine is allowed to sleep. It may sleep allocating metadata 885 * indirectly through swp_pager_meta_build() or if paging is still in 886 * progress on the source. 887 * 888 * The source object contains no vm_page_t's (which is just as well) 889 * 890 * The source object is of type OBJT_SWAP. 891 * 892 * The source and destination objects must be locked. 893 * Both object locks may temporarily be released. 894 */ 895void 896swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 897 vm_pindex_t offset, int destroysource) 898{ 899 vm_pindex_t i; 900 901 VM_OBJECT_ASSERT_WLOCKED(srcobject); 902 VM_OBJECT_ASSERT_WLOCKED(dstobject); 903 904 /* 905 * If destroysource is set, we remove the source object from the 906 * swap_pager internal queue now. 907 */ 908 if (destroysource) { 909 if (srcobject->handle != NULL) { 910 mtx_lock(&sw_alloc_mtx); 911 TAILQ_REMOVE( 912 NOBJLIST(srcobject->handle), 913 srcobject, 914 pager_object_list 915 ); 916 mtx_unlock(&sw_alloc_mtx); 917 } 918 } 919 920 /* 921 * transfer source to destination. 922 */ 923 for (i = 0; i < dstobject->size; ++i) { 924 daddr_t dstaddr; 925 926 /* 927 * Locate (without changing) the swapblk on the destination, 928 * unless it is invalid in which case free it silently, or 929 * if the destination is a resident page, in which case the 930 * source is thrown away. 931 */ 932 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 933 934 if (dstaddr == SWAPBLK_NONE) { 935 /* 936 * Destination has no swapblk and is not resident, 937 * copy source. 938 */ 939 daddr_t srcaddr; 940 941 srcaddr = swp_pager_meta_ctl( 942 srcobject, 943 i + offset, 944 SWM_POP 945 ); 946 947 if (srcaddr != SWAPBLK_NONE) { 948 /* 949 * swp_pager_meta_build() can sleep. 950 */ 951 vm_object_pip_add(srcobject, 1); 952 VM_OBJECT_WUNLOCK(srcobject); 953 vm_object_pip_add(dstobject, 1); 954 swp_pager_meta_build(dstobject, i, srcaddr); 955 vm_object_pip_wakeup(dstobject); 956 VM_OBJECT_WLOCK(srcobject); 957 vm_object_pip_wakeup(srcobject); 958 } 959 } else { 960 /* 961 * Destination has valid swapblk or it is represented 962 * by a resident page. We destroy the sourceblock. 963 */ 964 965 swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE); 966 } 967 } 968 969 /* 970 * Free left over swap blocks in source. 971 * 972 * We have to revert the type to OBJT_DEFAULT so we do not accidently 973 * double-remove the object from the swap queues. 974 */ 975 if (destroysource) { 976 swp_pager_meta_free_all(srcobject); 977 /* 978 * Reverting the type is not necessary, the caller is going 979 * to destroy srcobject directly, but I'm doing it here 980 * for consistency since we've removed the object from its 981 * queues. 982 */ 983 srcobject->type = OBJT_DEFAULT; 984 } 985} 986 987/* 988 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 989 * the requested page. 990 * 991 * We determine whether good backing store exists for the requested 992 * page and return TRUE if it does, FALSE if it doesn't. 993 * 994 * If TRUE, we also try to determine how much valid, contiguous backing 995 * store exists before and after the requested page within a reasonable 996 * distance. We do not try to restrict it to the swap device stripe 997 * (that is handled in getpages/putpages). It probably isn't worth 998 * doing here. 999 */ 1000static boolean_t 1001swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after) 1002{ 1003 daddr_t blk0; 1004 1005 VM_OBJECT_ASSERT_LOCKED(object); 1006 /* 1007 * do we have good backing store at the requested index ? 1008 */ 1009 blk0 = swp_pager_meta_ctl(object, pindex, 0); 1010 1011 if (blk0 == SWAPBLK_NONE) { 1012 if (before) 1013 *before = 0; 1014 if (after) 1015 *after = 0; 1016 return (FALSE); 1017 } 1018 1019 /* 1020 * find backwards-looking contiguous good backing store 1021 */ 1022 if (before != NULL) { 1023 int i; 1024 1025 for (i = 1; i < (SWB_NPAGES/2); ++i) { 1026 daddr_t blk; 1027 1028 if (i > pindex) 1029 break; 1030 blk = swp_pager_meta_ctl(object, pindex - i, 0); 1031 if (blk != blk0 - i) 1032 break; 1033 } 1034 *before = (i - 1); 1035 } 1036 1037 /* 1038 * find forward-looking contiguous good backing store 1039 */ 1040 if (after != NULL) { 1041 int i; 1042 1043 for (i = 1; i < (SWB_NPAGES/2); ++i) { 1044 daddr_t blk; 1045 1046 blk = swp_pager_meta_ctl(object, pindex + i, 0); 1047 if (blk != blk0 + i) 1048 break; 1049 } 1050 *after = (i - 1); 1051 } 1052 return (TRUE); 1053} 1054 1055/* 1056 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1057 * 1058 * This removes any associated swap backing store, whether valid or 1059 * not, from the page. 1060 * 1061 * This routine is typically called when a page is made dirty, at 1062 * which point any associated swap can be freed. MADV_FREE also 1063 * calls us in a special-case situation 1064 * 1065 * NOTE!!! If the page is clean and the swap was valid, the caller 1066 * should make the page dirty before calling this routine. This routine 1067 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1068 * depends on it. 1069 * 1070 * This routine may not sleep. 1071 * 1072 * The object containing the page must be locked. 1073 */ 1074static void 1075swap_pager_unswapped(vm_page_t m) 1076{ 1077 1078 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); 1079} 1080 1081/* 1082 * SWAP_PAGER_GETPAGES() - bring pages in from swap 1083 * 1084 * Attempt to retrieve (m, count) pages from backing store, but make 1085 * sure we retrieve at least m[reqpage]. We try to load in as large 1086 * a chunk surrounding m[reqpage] as is contiguous in swap and which 1087 * belongs to the same object. 1088 * 1089 * The code is designed for asynchronous operation and 1090 * immediate-notification of 'reqpage' but tends not to be 1091 * used that way. Please do not optimize-out this algorithmic 1092 * feature, I intend to improve on it in the future. 1093 * 1094 * The parent has a single vm_object_pip_add() reference prior to 1095 * calling us and we should return with the same. 1096 * 1097 * The parent has BUSY'd the pages. We should return with 'm' 1098 * left busy, but the others adjusted. 1099 */ 1100static int 1101swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage) 1102{ 1103 struct buf *bp; 1104 vm_page_t mreq; 1105 int i; 1106 int j; 1107 daddr_t blk; 1108 1109 mreq = m[reqpage]; 1110 1111 KASSERT(mreq->object == object, 1112 ("swap_pager_getpages: object mismatch %p/%p", 1113 object, mreq->object)); 1114 1115 /* 1116 * Calculate range to retrieve. The pages have already been assigned 1117 * their swapblks. We require a *contiguous* range but we know it to 1118 * not span devices. If we do not supply it, bad things 1119 * happen. Note that blk, iblk & jblk can be SWAPBLK_NONE, but the 1120 * loops are set up such that the case(s) are handled implicitly. 1121 * 1122 * The swp_*() calls must be made with the object locked. 1123 */ 1124 blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0); 1125 1126 for (i = reqpage - 1; i >= 0; --i) { 1127 daddr_t iblk; 1128 1129 iblk = swp_pager_meta_ctl(m[i]->object, m[i]->pindex, 0); 1130 if (blk != iblk + (reqpage - i)) 1131 break; 1132 } 1133 ++i; 1134 1135 for (j = reqpage + 1; j < count; ++j) { 1136 daddr_t jblk; 1137 1138 jblk = swp_pager_meta_ctl(m[j]->object, m[j]->pindex, 0); 1139 if (blk != jblk - (j - reqpage)) 1140 break; 1141 } 1142 1143 /* 1144 * free pages outside our collection range. Note: we never free 1145 * mreq, it must remain busy throughout. 1146 */ 1147 if (0 < i || j < count) { 1148 int k; 1149 1150 for (k = 0; k < i; ++k) 1151 swp_pager_free_nrpage(m[k]); 1152 for (k = j; k < count; ++k) 1153 swp_pager_free_nrpage(m[k]); 1154 } 1155 1156 /* 1157 * Return VM_PAGER_FAIL if we have nothing to do. Return mreq 1158 * still busy, but the others unbusied. 1159 */ 1160 if (blk == SWAPBLK_NONE) 1161 return (VM_PAGER_FAIL); 1162 1163 /* 1164 * Getpbuf() can sleep. 1165 */ 1166 VM_OBJECT_WUNLOCK(object); 1167 /* 1168 * Get a swap buffer header to perform the IO 1169 */ 1170 bp = getpbuf(&nsw_rcount); 1171 bp->b_flags |= B_PAGING; 1172 1173 bp->b_iocmd = BIO_READ; 1174 bp->b_iodone = swp_pager_async_iodone; 1175 bp->b_rcred = crhold(thread0.td_ucred); 1176 bp->b_wcred = crhold(thread0.td_ucred); 1177 bp->b_blkno = blk - (reqpage - i); 1178 bp->b_bcount = PAGE_SIZE * (j - i); 1179 bp->b_bufsize = PAGE_SIZE * (j - i); 1180 bp->b_pager.pg_reqpage = reqpage - i; 1181 1182 VM_OBJECT_WLOCK(object); 1183 { 1184 int k; 1185 1186 for (k = i; k < j; ++k) { 1187 bp->b_pages[k - i] = m[k]; 1188 m[k]->oflags |= VPO_SWAPINPROG; 1189 } 1190 } 1191 bp->b_npages = j - i; 1192 1193 PCPU_INC(cnt.v_swapin); 1194 PCPU_ADD(cnt.v_swappgsin, bp->b_npages); 1195 1196 /* 1197 * We still hold the lock on mreq, and our automatic completion routine 1198 * does not remove it. 1199 */ 1200 vm_object_pip_add(object, bp->b_npages); 1201 VM_OBJECT_WUNLOCK(object); 1202 1203 /* 1204 * perform the I/O. NOTE!!! bp cannot be considered valid after 1205 * this point because we automatically release it on completion. 1206 * Instead, we look at the one page we are interested in which we 1207 * still hold a lock on even through the I/O completion. 1208 * 1209 * The other pages in our m[] array are also released on completion, 1210 * so we cannot assume they are valid anymore either. 1211 * 1212 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1213 */ 1214 BUF_KERNPROC(bp); 1215 swp_pager_strategy(bp); 1216 1217 /* 1218 * wait for the page we want to complete. VPO_SWAPINPROG is always 1219 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1220 * is set in the meta-data. 1221 */ 1222 VM_OBJECT_WLOCK(object); 1223 while ((mreq->oflags & VPO_SWAPINPROG) != 0) { 1224 mreq->oflags |= VPO_SWAPSLEEP; 1225 PCPU_INC(cnt.v_intrans); 1226 if (VM_OBJECT_SLEEP(object, &object->paging_in_progress, PSWP, 1227 "swread", hz * 20)) { 1228 printf( 1229"swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1230 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1231 } 1232 } 1233 1234 /* 1235 * mreq is left busied after completion, but all the other pages 1236 * are freed. If we had an unrecoverable read error the page will 1237 * not be valid. 1238 */ 1239 if (mreq->valid != VM_PAGE_BITS_ALL) { 1240 return (VM_PAGER_ERROR); 1241 } else { 1242 return (VM_PAGER_OK); 1243 } 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_putpages: 1255 * 1256 * Assign swap (if necessary) and initiate I/O on the specified pages. 1257 * 1258 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1259 * are automatically converted to SWAP objects. 1260 * 1261 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1262 * vm_page reservation system coupled with properly written VFS devices 1263 * should ensure that no low-memory deadlock occurs. This is an area 1264 * which needs work. 1265 * 1266 * The parent has N vm_object_pip_add() references prior to 1267 * calling us and will remove references for rtvals[] that are 1268 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1269 * completion. 1270 * 1271 * The parent has soft-busy'd the pages it passes us and will unbusy 1272 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1273 * We need to unbusy the rest on I/O completion. 1274 */ 1275void 1276swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1277 int flags, int *rtvals) 1278{ 1279 int i, n; 1280 boolean_t sync; 1281 1282 if (count && m[0]->object != object) { 1283 panic("swap_pager_putpages: object mismatch %p/%p", 1284 object, 1285 m[0]->object 1286 ); 1287 } 1288 1289 /* 1290 * Step 1 1291 * 1292 * Turn object into OBJT_SWAP 1293 * check for bogus sysops 1294 * force sync if not pageout process 1295 */ 1296 if (object->type != OBJT_SWAP) 1297 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1298 VM_OBJECT_WUNLOCK(object); 1299 1300 n = 0; 1301 if (curproc != pageproc) 1302 sync = TRUE; 1303 else 1304 sync = (flags & VM_PAGER_PUT_SYNC) != 0; 1305 1306 /* 1307 * Step 2 1308 * 1309 * Update nsw parameters from swap_async_max sysctl values. 1310 * Do not let the sysop crash the machine with bogus numbers. 1311 */ 1312 mtx_lock(&pbuf_mtx); 1313 if (swap_async_max != nsw_wcount_async_max) { 1314 int n; 1315 1316 /* 1317 * limit range 1318 */ 1319 if ((n = swap_async_max) > nswbuf / 2) 1320 n = nswbuf / 2; 1321 if (n < 1) 1322 n = 1; 1323 swap_async_max = n; 1324 1325 /* 1326 * Adjust difference ( if possible ). If the current async 1327 * count is too low, we may not be able to make the adjustment 1328 * at this time. 1329 */ 1330 n -= nsw_wcount_async_max; 1331 if (nsw_wcount_async + n >= 0) { 1332 nsw_wcount_async += n; 1333 nsw_wcount_async_max += n; 1334 wakeup(&nsw_wcount_async); 1335 } 1336 } 1337 mtx_unlock(&pbuf_mtx); 1338 1339 /* 1340 * Step 3 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 rtvals[i+j] = VM_PAGER_OK; 1405 1406 mreq->oflags |= VPO_SWAPINPROG; 1407 bp->b_pages[j] = mreq; 1408 } 1409 VM_OBJECT_WUNLOCK(object); 1410 bp->b_npages = n; 1411 /* 1412 * Must set dirty range for NFS to work. 1413 */ 1414 bp->b_dirtyoff = 0; 1415 bp->b_dirtyend = bp->b_bcount; 1416 1417 PCPU_INC(cnt.v_swapout); 1418 PCPU_ADD(cnt.v_swappgsout, bp->b_npages); 1419 1420 /* 1421 * asynchronous 1422 * 1423 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1424 */ 1425 if (sync == FALSE) { 1426 bp->b_iodone = swp_pager_async_iodone; 1427 BUF_KERNPROC(bp); 1428 swp_pager_strategy(bp); 1429 1430 for (j = 0; j < n; ++j) 1431 rtvals[i+j] = VM_PAGER_PEND; 1432 /* restart outter loop */ 1433 continue; 1434 } 1435 1436 /* 1437 * synchronous 1438 * 1439 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1440 */ 1441 bp->b_iodone = bdone; 1442 swp_pager_strategy(bp); 1443 1444 /* 1445 * Wait for the sync I/O to complete, then update rtvals. 1446 * We just set the rtvals[] to VM_PAGER_PEND so we can call 1447 * our async completion routine at the end, thus avoiding a 1448 * double-free. 1449 */ 1450 bwait(bp, PVM, "swwrt"); 1451 for (j = 0; j < n; ++j) 1452 rtvals[i+j] = VM_PAGER_PEND; 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 */ 1470static void 1471swp_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 ((bp->b_flags & B_UNMAPPED) != 0) { 1494 bp->b_data = bp->b_kvaalloc; 1495 bp->b_kvabase = bp->b_kvaalloc; 1496 bp->b_flags &= ~B_UNMAPPED; 1497 } else 1498 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1499 1500 if (bp->b_npages) { 1501 object = bp->b_pages[0]->object; 1502 VM_OBJECT_WLOCK(object); 1503 } 1504 1505 /* 1506 * cleanup pages. If an error occurs writing to swap, we are in 1507 * very serious trouble. If it happens to be a disk error, though, 1508 * we may be able to recover by reassigning the swap later on. So 1509 * in this case we remove the m->swapblk assignment for the page 1510 * but do not free it in the rlist. The errornous block(s) are thus 1511 * never reallocated as swap. Redirty the page and continue. 1512 */ 1513 for (i = 0; i < bp->b_npages; ++i) { 1514 vm_page_t m = bp->b_pages[i]; 1515 1516 m->oflags &= ~VPO_SWAPINPROG; 1517 if (m->oflags & VPO_SWAPSLEEP) { 1518 m->oflags &= ~VPO_SWAPSLEEP; 1519 wakeup(&object->paging_in_progress); 1520 } 1521 1522 if (bp->b_ioflags & BIO_ERROR) { 1523 /* 1524 * If an error occurs I'd love to throw the swapblk 1525 * away without freeing it back to swapspace, so it 1526 * can never be used again. But I can't from an 1527 * interrupt. 1528 */ 1529 if (bp->b_iocmd == BIO_READ) { 1530 /* 1531 * When reading, reqpage needs to stay 1532 * locked for the parent, but all other 1533 * pages can be freed. We still want to 1534 * wakeup the parent waiting on the page, 1535 * though. ( also: pg_reqpage can be -1 and 1536 * not match anything ). 1537 * 1538 * We have to wake specifically requested pages 1539 * up too because we cleared VPO_SWAPINPROG and 1540 * someone may be waiting for that. 1541 * 1542 * NOTE: for reads, m->dirty will probably 1543 * be overridden by the original caller of 1544 * getpages so don't play cute tricks here. 1545 */ 1546 m->valid = 0; 1547 if (i != bp->b_pager.pg_reqpage) 1548 swp_pager_free_nrpage(m); 1549 else { 1550 vm_page_lock(m); 1551 vm_page_flash(m); 1552 vm_page_unlock(m); 1553 } 1554 /* 1555 * If i == bp->b_pager.pg_reqpage, do not wake 1556 * the page up. The caller needs to. 1557 */ 1558 } else { 1559 /* 1560 * If a write error occurs, reactivate page 1561 * so it doesn't clog the inactive list, 1562 * then finish the I/O. 1563 */ 1564 vm_page_dirty(m); 1565 vm_page_lock(m); 1566 vm_page_activate(m); 1567 vm_page_unlock(m); 1568 vm_page_sunbusy(m); 1569 } 1570 } else if (bp->b_iocmd == BIO_READ) { 1571 /* 1572 * NOTE: for reads, m->dirty will probably be 1573 * overridden by the original caller of getpages so 1574 * we cannot set them in order to free the underlying 1575 * swap in a low-swap situation. I don't think we'd 1576 * want to do that anyway, but it was an optimization 1577 * that existed in the old swapper for a time before 1578 * it got ripped out due to precisely this problem. 1579 * 1580 * If not the requested page then deactivate it. 1581 * 1582 * Note that the requested page, reqpage, is left 1583 * busied, but we still have to wake it up. The 1584 * other pages are released (unbusied) by 1585 * vm_page_xunbusy(). 1586 */ 1587 KASSERT(!pmap_page_is_mapped(m), 1588 ("swp_pager_async_iodone: page %p is mapped", m)); 1589 m->valid = VM_PAGE_BITS_ALL; 1590 KASSERT(m->dirty == 0, 1591 ("swp_pager_async_iodone: page %p is dirty", m)); 1592 1593 /* 1594 * We have to wake specifically requested pages 1595 * up too because we cleared VPO_SWAPINPROG and 1596 * could be waiting for it in getpages. However, 1597 * be sure to not unbusy getpages specifically 1598 * requested page - getpages expects it to be 1599 * left busy. 1600 */ 1601 if (i != bp->b_pager.pg_reqpage) { 1602 vm_page_lock(m); 1603 vm_page_deactivate(m); 1604 vm_page_unlock(m); 1605 vm_page_xunbusy(m); 1606 } else { 1607 vm_page_lock(m); 1608 vm_page_flash(m); 1609 vm_page_unlock(m); 1610 } 1611 } else { 1612 /* 1613 * For write success, clear the dirty 1614 * status, then finish the I/O ( which decrements the 1615 * busy count and possibly wakes waiter's up ). 1616 */ 1617 KASSERT(!pmap_page_is_write_mapped(m), 1618 ("swp_pager_async_iodone: page %p is not write" 1619 " protected", m)); 1620 vm_page_undirty(m); 1621 vm_page_sunbusy(m); 1622 if (vm_page_count_severe()) { 1623 vm_page_lock(m); 1624 vm_page_try_to_cache(m); 1625 vm_page_unlock(m); 1626 } 1627 } 1628 } 1629 1630 /* 1631 * adjust pip. NOTE: the original parent may still have its own 1632 * pip refs on the object. 1633 */ 1634 if (object != NULL) { 1635 vm_object_pip_wakeupn(object, bp->b_npages); 1636 VM_OBJECT_WUNLOCK(object); 1637 } 1638 1639 /* 1640 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1641 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1642 * trigger a KASSERT in relpbuf(). 1643 */ 1644 if (bp->b_vp) { 1645 bp->b_vp = NULL; 1646 bp->b_bufobj = NULL; 1647 } 1648 /* 1649 * release the physical I/O buffer 1650 */ 1651 relpbuf( 1652 bp, 1653 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount : 1654 ((bp->b_flags & B_ASYNC) ? 1655 &nsw_wcount_async : 1656 &nsw_wcount_sync 1657 ) 1658 ) 1659 ); 1660} 1661 1662/* 1663 * swap_pager_isswapped: 1664 * 1665 * Return 1 if at least one page in the given object is paged 1666 * out to the given swap device. 1667 * 1668 * This routine may not sleep. 1669 */ 1670int 1671swap_pager_isswapped(vm_object_t object, struct swdevt *sp) 1672{ 1673 daddr_t index = 0; 1674 int bcount; 1675 int i; 1676 1677 VM_OBJECT_ASSERT_WLOCKED(object); 1678 if (object->type != OBJT_SWAP) 1679 return (0); 1680 1681 mtx_lock(&swhash_mtx); 1682 for (bcount = 0; bcount < object->un_pager.swp.swp_bcount; bcount++) { 1683 struct swblock *swap; 1684 1685 if ((swap = *swp_pager_hash(object, index)) != NULL) { 1686 for (i = 0; i < SWAP_META_PAGES; ++i) { 1687 if (swp_pager_isondev(swap->swb_pages[i], sp)) { 1688 mtx_unlock(&swhash_mtx); 1689 return (1); 1690 } 1691 } 1692 } 1693 index += SWAP_META_PAGES; 1694 } 1695 mtx_unlock(&swhash_mtx); 1696 return (0); 1697} 1698 1699/* 1700 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in 1701 * 1702 * This routine dissociates the page at the given index within a 1703 * swap block from its backing store, paging it in if necessary. 1704 * If the page is paged in, it is placed in the inactive queue, 1705 * since it had its backing store ripped out from under it. 1706 * We also attempt to swap in all other pages in the swap block, 1707 * we only guarantee that the one at the specified index is 1708 * paged in. 1709 * 1710 * XXX - The code to page the whole block in doesn't work, so we 1711 * revert to the one-by-one behavior for now. Sigh. 1712 */ 1713static inline void 1714swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex) 1715{ 1716 vm_page_t m; 1717 1718 vm_object_pip_add(object, 1); 1719 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL); 1720 if (m->valid == VM_PAGE_BITS_ALL) { 1721 vm_object_pip_subtract(object, 1); 1722 vm_page_dirty(m); 1723 vm_page_lock(m); 1724 vm_page_activate(m); 1725 vm_page_unlock(m); 1726 vm_page_xunbusy(m); 1727 vm_pager_page_unswapped(m); 1728 return; 1729 } 1730 1731 if (swap_pager_getpages(object, &m, 1, 0) != VM_PAGER_OK) 1732 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/ 1733 vm_object_pip_subtract(object, 1); 1734 vm_page_dirty(m); 1735 vm_page_lock(m); 1736 vm_page_deactivate(m); 1737 vm_page_unlock(m); 1738 vm_page_xunbusy(m); 1739 vm_pager_page_unswapped(m); 1740} 1741 1742/* 1743 * swap_pager_swapoff: 1744 * 1745 * Page in all of the pages that have been paged out to the 1746 * given device. The corresponding blocks in the bitmap must be 1747 * marked as allocated and the device must be flagged SW_CLOSING. 1748 * There may be no processes swapped out to the device. 1749 * 1750 * This routine may block. 1751 */ 1752static void 1753swap_pager_swapoff(struct swdevt *sp) 1754{ 1755 struct swblock *swap; 1756 vm_object_t locked_obj, object; 1757 vm_pindex_t pindex; 1758 int i, j, retries; 1759 1760 GIANT_REQUIRED; 1761 1762 retries = 0; 1763 locked_obj = NULL; 1764full_rescan: 1765 mtx_lock(&swhash_mtx); 1766 for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */ 1767restart: 1768 for (swap = swhash[i]; swap != NULL; swap = swap->swb_hnext) { 1769 object = swap->swb_object; 1770 pindex = swap->swb_index; 1771 for (j = 0; j < SWAP_META_PAGES; ++j) { 1772 if (!swp_pager_isondev(swap->swb_pages[j], sp)) 1773 continue; 1774 if (locked_obj != object) { 1775 if (locked_obj != NULL) 1776 VM_OBJECT_WUNLOCK(locked_obj); 1777 locked_obj = object; 1778 if (!VM_OBJECT_TRYWLOCK(object)) { 1779 mtx_unlock(&swhash_mtx); 1780 /* Depends on type-stability. */ 1781 VM_OBJECT_WLOCK(object); 1782 mtx_lock(&swhash_mtx); 1783 goto restart; 1784 } 1785 } 1786 MPASS(locked_obj == object); 1787 mtx_unlock(&swhash_mtx); 1788 swp_pager_force_pagein(object, pindex + j); 1789 mtx_lock(&swhash_mtx); 1790 goto restart; 1791 } 1792 } 1793 } 1794 mtx_unlock(&swhash_mtx); 1795 if (locked_obj != NULL) { 1796 VM_OBJECT_WUNLOCK(locked_obj); 1797 locked_obj = NULL; 1798 } 1799 if (sp->sw_used) { 1800 /* 1801 * Objects may be locked or paging to the device being 1802 * removed, so we will miss their pages and need to 1803 * make another pass. We have marked this device as 1804 * SW_CLOSING, so the activity should finish soon. 1805 */ 1806 retries++; 1807 if (retries > 100) { 1808 panic("swapoff: failed to locate %d swap blocks", 1809 sp->sw_used); 1810 } 1811 pause("swpoff", hz / 20); 1812 goto full_rescan; 1813 } 1814} 1815 1816/************************************************************************ 1817 * SWAP META DATA * 1818 ************************************************************************ 1819 * 1820 * These routines manipulate the swap metadata stored in the 1821 * OBJT_SWAP object. 1822 * 1823 * Swap metadata is implemented with a global hash and not directly 1824 * linked into the object. Instead the object simply contains 1825 * appropriate tracking counters. 1826 */ 1827 1828/* 1829 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1830 * 1831 * We first convert the object to a swap object if it is a default 1832 * object. 1833 * 1834 * The specified swapblk is added to the object's swap metadata. If 1835 * the swapblk is not valid, it is freed instead. Any previously 1836 * assigned swapblk is freed. 1837 */ 1838static void 1839swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1840{ 1841 static volatile int exhausted; 1842 struct swblock *swap; 1843 struct swblock **pswap; 1844 int idx; 1845 1846 VM_OBJECT_ASSERT_WLOCKED(object); 1847 /* 1848 * Convert default object to swap object if necessary 1849 */ 1850 if (object->type != OBJT_SWAP) { 1851 object->type = OBJT_SWAP; 1852 object->un_pager.swp.swp_bcount = 0; 1853 1854 if (object->handle != NULL) { 1855 mtx_lock(&sw_alloc_mtx); 1856 TAILQ_INSERT_TAIL( 1857 NOBJLIST(object->handle), 1858 object, 1859 pager_object_list 1860 ); 1861 mtx_unlock(&sw_alloc_mtx); 1862 } 1863 } 1864 1865 /* 1866 * Locate hash entry. If not found create, but if we aren't adding 1867 * anything just return. If we run out of space in the map we wait 1868 * and, since the hash table may have changed, retry. 1869 */ 1870retry: 1871 mtx_lock(&swhash_mtx); 1872 pswap = swp_pager_hash(object, pindex); 1873 1874 if ((swap = *pswap) == NULL) { 1875 int i; 1876 1877 if (swapblk == SWAPBLK_NONE) 1878 goto done; 1879 1880 swap = *pswap = uma_zalloc(swap_zone, M_NOWAIT | 1881 (curproc == pageproc ? M_USE_RESERVE : 0)); 1882 if (swap == NULL) { 1883 mtx_unlock(&swhash_mtx); 1884 VM_OBJECT_WUNLOCK(object); 1885 if (uma_zone_exhausted(swap_zone)) { 1886 if (atomic_cmpset_int(&exhausted, 0, 1)) 1887 printf("swap zone exhausted, " 1888 "increase kern.maxswzone\n"); 1889 vm_pageout_oom(VM_OOM_SWAPZ); 1890 pause("swzonex", 10); 1891 } else 1892 VM_WAIT; 1893 VM_OBJECT_WLOCK(object); 1894 goto retry; 1895 } 1896 1897 if (atomic_cmpset_int(&exhausted, 1, 0)) 1898 printf("swap zone ok\n"); 1899 1900 swap->swb_hnext = NULL; 1901 swap->swb_object = object; 1902 swap->swb_index = pindex & ~(vm_pindex_t)SWAP_META_MASK; 1903 swap->swb_count = 0; 1904 1905 ++object->un_pager.swp.swp_bcount; 1906 1907 for (i = 0; i < SWAP_META_PAGES; ++i) 1908 swap->swb_pages[i] = SWAPBLK_NONE; 1909 } 1910 1911 /* 1912 * Delete prior contents of metadata 1913 */ 1914 idx = pindex & SWAP_META_MASK; 1915 1916 if (swap->swb_pages[idx] != SWAPBLK_NONE) { 1917 swp_pager_freeswapspace(swap->swb_pages[idx], 1); 1918 --swap->swb_count; 1919 } 1920 1921 /* 1922 * Enter block into metadata 1923 */ 1924 swap->swb_pages[idx] = swapblk; 1925 if (swapblk != SWAPBLK_NONE) 1926 ++swap->swb_count; 1927done: 1928 mtx_unlock(&swhash_mtx); 1929} 1930 1931/* 1932 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 1933 * 1934 * The requested range of blocks is freed, with any associated swap 1935 * returned to the swap bitmap. 1936 * 1937 * This routine will free swap metadata structures as they are cleaned 1938 * out. This routine does *NOT* operate on swap metadata associated 1939 * with resident pages. 1940 */ 1941static void 1942swp_pager_meta_free(vm_object_t object, vm_pindex_t index, daddr_t count) 1943{ 1944 1945 VM_OBJECT_ASSERT_LOCKED(object); 1946 if (object->type != OBJT_SWAP) 1947 return; 1948 1949 while (count > 0) { 1950 struct swblock **pswap; 1951 struct swblock *swap; 1952 1953 mtx_lock(&swhash_mtx); 1954 pswap = swp_pager_hash(object, index); 1955 1956 if ((swap = *pswap) != NULL) { 1957 daddr_t v = swap->swb_pages[index & SWAP_META_MASK]; 1958 1959 if (v != SWAPBLK_NONE) { 1960 swp_pager_freeswapspace(v, 1); 1961 swap->swb_pages[index & SWAP_META_MASK] = 1962 SWAPBLK_NONE; 1963 if (--swap->swb_count == 0) { 1964 *pswap = swap->swb_hnext; 1965 uma_zfree(swap_zone, swap); 1966 --object->un_pager.swp.swp_bcount; 1967 } 1968 } 1969 --count; 1970 ++index; 1971 } else { 1972 int n = SWAP_META_PAGES - (index & SWAP_META_MASK); 1973 count -= n; 1974 index += n; 1975 } 1976 mtx_unlock(&swhash_mtx); 1977 } 1978} 1979 1980/* 1981 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 1982 * 1983 * This routine locates and destroys all swap metadata associated with 1984 * an object. 1985 */ 1986static void 1987swp_pager_meta_free_all(vm_object_t object) 1988{ 1989 struct swblock **pswap, *swap; 1990 vm_pindex_t index; 1991 daddr_t v; 1992 int i; 1993 1994 VM_OBJECT_ASSERT_WLOCKED(object); 1995 if (object->type != OBJT_SWAP) 1996 return; 1997 1998 index = 0; 1999 while (object->un_pager.swp.swp_bcount != 0) { 2000 mtx_lock(&swhash_mtx); 2001 pswap = swp_pager_hash(object, index); 2002 if ((swap = *pswap) != NULL) { 2003 for (i = 0; i < SWAP_META_PAGES; ++i) { 2004 v = swap->swb_pages[i]; 2005 if (v != SWAPBLK_NONE) { 2006 --swap->swb_count; 2007 swp_pager_freeswapspace(v, 1); 2008 } 2009 } 2010 if (swap->swb_count != 0) 2011 panic( 2012 "swap_pager_meta_free_all: swb_count != 0"); 2013 *pswap = swap->swb_hnext; 2014 uma_zfree(swap_zone, swap); 2015 --object->un_pager.swp.swp_bcount; 2016 } 2017 mtx_unlock(&swhash_mtx); 2018 index += SWAP_META_PAGES; 2019 } 2020} 2021 2022/* 2023 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. 2024 * 2025 * This routine is capable of looking up, popping, or freeing 2026 * swapblk assignments in the swap meta data or in the vm_page_t. 2027 * The routine typically returns the swapblk being looked-up, or popped, 2028 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block 2029 * was invalid. This routine will automatically free any invalid 2030 * meta-data swapblks. 2031 * 2032 * It is not possible to store invalid swapblks in the swap meta data 2033 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking. 2034 * 2035 * When acting on a busy resident page and paging is in progress, we 2036 * have to wait until paging is complete but otherwise can act on the 2037 * busy page. 2038 * 2039 * SWM_FREE remove and free swap block from metadata 2040 * SWM_POP remove from meta data but do not free.. pop it out 2041 */ 2042static daddr_t 2043swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags) 2044{ 2045 struct swblock **pswap; 2046 struct swblock *swap; 2047 daddr_t r1; 2048 int idx; 2049 2050 VM_OBJECT_ASSERT_LOCKED(object); 2051 /* 2052 * The meta data only exists of the object is OBJT_SWAP 2053 * and even then might not be allocated yet. 2054 */ 2055 if (object->type != OBJT_SWAP) 2056 return (SWAPBLK_NONE); 2057 2058 r1 = SWAPBLK_NONE; 2059 mtx_lock(&swhash_mtx); 2060 pswap = swp_pager_hash(object, pindex); 2061 2062 if ((swap = *pswap) != NULL) { 2063 idx = pindex & SWAP_META_MASK; 2064 r1 = swap->swb_pages[idx]; 2065 2066 if (r1 != SWAPBLK_NONE) { 2067 if (flags & SWM_FREE) { 2068 swp_pager_freeswapspace(r1, 1); 2069 r1 = SWAPBLK_NONE; 2070 } 2071 if (flags & (SWM_FREE|SWM_POP)) { 2072 swap->swb_pages[idx] = SWAPBLK_NONE; 2073 if (--swap->swb_count == 0) { 2074 *pswap = swap->swb_hnext; 2075 uma_zfree(swap_zone, swap); 2076 --object->un_pager.swp.swp_bcount; 2077 } 2078 } 2079 } 2080 } 2081 mtx_unlock(&swhash_mtx); 2082 return (r1); 2083} 2084 2085/* 2086 * System call swapon(name) enables swapping on device name, 2087 * which must be in the swdevsw. Return EBUSY 2088 * if already swapping on this device. 2089 */ 2090#ifndef _SYS_SYSPROTO_H_ 2091struct swapon_args { 2092 char *name; 2093}; 2094#endif 2095 2096/* 2097 * MPSAFE 2098 */ 2099/* ARGSUSED */ 2100int 2101sys_swapon(struct thread *td, struct swapon_args *uap) 2102{ 2103 struct vattr attr; 2104 struct vnode *vp; 2105 struct nameidata nd; 2106 int error; 2107 2108 error = priv_check(td, PRIV_SWAPON); 2109 if (error) 2110 return (error); 2111 2112 mtx_lock(&Giant); 2113 while (swdev_syscall_active) 2114 tsleep(&swdev_syscall_active, PUSER - 1, "swpon", 0); 2115 swdev_syscall_active = 1; 2116 2117 /* 2118 * Swap metadata may not fit in the KVM if we have physical 2119 * memory of >1GB. 2120 */ 2121 if (swap_zone == NULL) { 2122 error = ENOMEM; 2123 goto done; 2124 } 2125 2126 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2127 uap->name, td); 2128 error = namei(&nd); 2129 if (error) 2130 goto done; 2131 2132 NDFREE(&nd, NDF_ONLY_PNBUF); 2133 vp = nd.ni_vp; 2134 2135 if (vn_isdisk(vp, &error)) { 2136 error = swapongeom(td, vp); 2137 } else if (vp->v_type == VREG && 2138 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2139 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2140 /* 2141 * Allow direct swapping to NFS regular files in the same 2142 * way that nfs_mountroot() sets up diskless swapping. 2143 */ 2144 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2145 } 2146 2147 if (error) 2148 vrele(vp); 2149done: 2150 swdev_syscall_active = 0; 2151 wakeup_one(&swdev_syscall_active); 2152 mtx_unlock(&Giant); 2153 return (error); 2154} 2155 2156/* 2157 * Check that the total amount of swap currently configured does not 2158 * exceed half the theoretical maximum. If it does, print a warning 2159 * message and return -1; otherwise, return 0. 2160 */ 2161static int 2162swapon_check_swzone(unsigned long npages) 2163{ 2164 unsigned long maxpages; 2165 2166 /* absolute maximum we can handle assuming 100% efficiency */ 2167 maxpages = uma_zone_get_max(swap_zone) * SWAP_META_PAGES; 2168 2169 /* recommend using no more than half that amount */ 2170 if (npages > maxpages / 2) { 2171 printf("warning: total configured swap (%lu pages) " 2172 "exceeds maximum recommended amount (%lu pages).\n", 2173 npages, maxpages / 2); 2174 printf("warning: increase kern.maxswzone " 2175 "or reduce amount of swap.\n"); 2176 return (-1); 2177 } 2178 return (0); 2179} 2180 2181static void 2182swaponsomething(struct vnode *vp, void *id, u_long nblks, 2183 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2184{ 2185 struct swdevt *sp, *tsp; 2186 swblk_t dvbase; 2187 u_long mblocks; 2188 2189 /* 2190 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2191 * First chop nblks off to page-align it, then convert. 2192 * 2193 * sw->sw_nblks is in page-sized chunks now too. 2194 */ 2195 nblks &= ~(ctodb(1) - 1); 2196 nblks = dbtoc(nblks); 2197 2198 /* 2199 * If we go beyond this, we get overflows in the radix 2200 * tree bitmap code. 2201 */ 2202 mblocks = 0x40000000 / BLIST_META_RADIX; 2203 if (nblks > mblocks) { 2204 printf( 2205 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2206 mblocks / 1024 / 1024 * PAGE_SIZE); 2207 nblks = mblocks; 2208 } 2209 2210 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2211 sp->sw_vp = vp; 2212 sp->sw_id = id; 2213 sp->sw_dev = dev; 2214 sp->sw_flags = 0; 2215 sp->sw_nblks = nblks; 2216 sp->sw_used = 0; 2217 sp->sw_strategy = strategy; 2218 sp->sw_close = close; 2219 sp->sw_flags = flags; 2220 2221 sp->sw_blist = blist_create(nblks, M_WAITOK); 2222 /* 2223 * Do not free the first two block in order to avoid overwriting 2224 * any bsd label at the front of the partition 2225 */ 2226 blist_free(sp->sw_blist, 2, nblks - 2); 2227 2228 dvbase = 0; 2229 mtx_lock(&sw_dev_mtx); 2230 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2231 if (tsp->sw_end >= dvbase) { 2232 /* 2233 * We put one uncovered page between the devices 2234 * in order to definitively prevent any cross-device 2235 * I/O requests 2236 */ 2237 dvbase = tsp->sw_end + 1; 2238 } 2239 } 2240 sp->sw_first = dvbase; 2241 sp->sw_end = dvbase + nblks; 2242 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2243 nswapdev++; 2244 swap_pager_avail += nblks - 2; 2245 swap_total += (vm_ooffset_t)nblks * PAGE_SIZE; 2246 swapon_check_swzone(swap_total / PAGE_SIZE); 2247 swp_sizecheck(); 2248 mtx_unlock(&sw_dev_mtx); 2249} 2250 2251/* 2252 * SYSCALL: swapoff(devname) 2253 * 2254 * Disable swapping on the given device. 2255 * 2256 * XXX: Badly designed system call: it should use a device index 2257 * rather than filename as specification. We keep sw_vp around 2258 * only to make this work. 2259 */ 2260#ifndef _SYS_SYSPROTO_H_ 2261struct swapoff_args { 2262 char *name; 2263}; 2264#endif 2265 2266/* 2267 * MPSAFE 2268 */ 2269/* ARGSUSED */ 2270int 2271sys_swapoff(struct thread *td, struct swapoff_args *uap) 2272{ 2273 struct vnode *vp; 2274 struct nameidata nd; 2275 struct swdevt *sp; 2276 int error; 2277 2278 error = priv_check(td, PRIV_SWAPOFF); 2279 if (error) 2280 return (error); 2281 2282 mtx_lock(&Giant); 2283 while (swdev_syscall_active) 2284 tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0); 2285 swdev_syscall_active = 1; 2286 2287 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2288 td); 2289 error = namei(&nd); 2290 if (error) 2291 goto done; 2292 NDFREE(&nd, NDF_ONLY_PNBUF); 2293 vp = nd.ni_vp; 2294 2295 mtx_lock(&sw_dev_mtx); 2296 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2297 if (sp->sw_vp == vp) 2298 break; 2299 } 2300 mtx_unlock(&sw_dev_mtx); 2301 if (sp == NULL) { 2302 error = EINVAL; 2303 goto done; 2304 } 2305 error = swapoff_one(sp, td->td_ucred); 2306done: 2307 swdev_syscall_active = 0; 2308 wakeup_one(&swdev_syscall_active); 2309 mtx_unlock(&Giant); 2310 return (error); 2311} 2312 2313static int 2314swapoff_one(struct swdevt *sp, struct ucred *cred) 2315{ 2316 u_long nblks; 2317#ifdef MAC 2318 int error; 2319#endif 2320 2321 mtx_assert(&Giant, MA_OWNED); 2322#ifdef MAC 2323 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2324 error = mac_system_check_swapoff(cred, sp->sw_vp); 2325 (void) VOP_UNLOCK(sp->sw_vp, 0); 2326 if (error != 0) 2327 return (error); 2328#endif 2329 nblks = sp->sw_nblks; 2330 2331 /* 2332 * We can turn off this swap device safely only if the 2333 * available virtual memory in the system will fit the amount 2334 * of data we will have to page back in, plus an epsilon so 2335 * the system doesn't become critically low on swap space. 2336 */ 2337 if (cnt.v_free_count + cnt.v_cache_count + swap_pager_avail < 2338 nblks + nswap_lowat) { 2339 return (ENOMEM); 2340 } 2341 2342 /* 2343 * Prevent further allocations on this device. 2344 */ 2345 mtx_lock(&sw_dev_mtx); 2346 sp->sw_flags |= SW_CLOSING; 2347 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2348 swap_total -= (vm_ooffset_t)nblks * PAGE_SIZE; 2349 mtx_unlock(&sw_dev_mtx); 2350 2351 /* 2352 * Page in the contents of the device and close it. 2353 */ 2354 swap_pager_swapoff(sp); 2355 2356 sp->sw_close(curthread, sp); 2357 mtx_lock(&sw_dev_mtx); 2358 sp->sw_id = NULL; 2359 TAILQ_REMOVE(&swtailq, sp, sw_list); 2360 nswapdev--; 2361 if (nswapdev == 0) { 2362 swap_pager_full = 2; 2363 swap_pager_almost_full = 1; 2364 } 2365 if (swdevhd == sp) 2366 swdevhd = NULL; 2367 mtx_unlock(&sw_dev_mtx); 2368 blist_destroy(sp->sw_blist); 2369 free(sp, M_VMPGDATA); 2370 return (0); 2371} 2372 2373void 2374swapoff_all(void) 2375{ 2376 struct swdevt *sp, *spt; 2377 const char *devname; 2378 int error; 2379 2380 mtx_lock(&Giant); 2381 while (swdev_syscall_active) 2382 tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0); 2383 swdev_syscall_active = 1; 2384 2385 mtx_lock(&sw_dev_mtx); 2386 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2387 mtx_unlock(&sw_dev_mtx); 2388 if (vn_isdisk(sp->sw_vp, NULL)) 2389 devname = devtoname(sp->sw_vp->v_rdev); 2390 else 2391 devname = "[file]"; 2392 error = swapoff_one(sp, thread0.td_ucred); 2393 if (error != 0) { 2394 printf("Cannot remove swap device %s (error=%d), " 2395 "skipping.\n", devname, error); 2396 } else if (bootverbose) { 2397 printf("Swap device %s removed.\n", devname); 2398 } 2399 mtx_lock(&sw_dev_mtx); 2400 } 2401 mtx_unlock(&sw_dev_mtx); 2402 2403 swdev_syscall_active = 0; 2404 wakeup_one(&swdev_syscall_active); 2405 mtx_unlock(&Giant); 2406} 2407 2408void 2409swap_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 2423int 2424swap_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 2457static int 2458sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2459{ 2460 struct xswdev xs; 2461 int error; 2462 2463 if (arg2 != 1) /* name length */ 2464 return (EINVAL); 2465 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2466 if (error != 0) 2467 return (error); 2468 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2469 return (error); 2470} 2471 2472SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2473 "Number of swap devices"); 2474SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD, sysctl_vm_swap_info, 2475 "Swap statistics by device"); 2476 2477/* 2478 * vmspace_swap_count() - count the approximate swap usage in pages for a 2479 * vmspace. 2480 * 2481 * The map must be locked. 2482 * 2483 * Swap usage is determined by taking the proportional swap used by 2484 * VM objects backing the VM map. To make up for fractional losses, 2485 * if the VM object has any swap use at all the associated map entries 2486 * count for at least 1 swap page. 2487 */ 2488long 2489vmspace_swap_count(struct vmspace *vmspace) 2490{ 2491 vm_map_t map; 2492 vm_map_entry_t cur; 2493 vm_object_t object; 2494 long count, n; 2495 2496 map = &vmspace->vm_map; 2497 count = 0; 2498 2499 for (cur = map->header.next; cur != &map->header; cur = cur->next) { 2500 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 && 2501 (object = cur->object.vm_object) != NULL) { 2502 VM_OBJECT_WLOCK(object); 2503 if (object->type == OBJT_SWAP && 2504 object->un_pager.swp.swp_bcount != 0) { 2505 n = (cur->end - cur->start) / PAGE_SIZE; 2506 count += object->un_pager.swp.swp_bcount * 2507 SWAP_META_PAGES * n / object->size + 1; 2508 } 2509 VM_OBJECT_WUNLOCK(object); 2510 } 2511 } 2512 return (count); 2513} 2514 2515/* 2516 * GEOM backend 2517 * 2518 * Swapping onto disk devices. 2519 * 2520 */ 2521 2522static g_orphan_t swapgeom_orphan; 2523 2524static struct g_class g_swap_class = { 2525 .name = "SWAP", 2526 .version = G_VERSION, 2527 .orphan = swapgeom_orphan, 2528}; 2529 2530DECLARE_GEOM_CLASS(g_swap_class, g_class); 2531 2532 2533static void 2534swapgeom_close_ev(void *arg, int flags) 2535{ 2536 struct g_consumer *cp; 2537 2538 cp = arg; 2539 g_access(cp, -1, -1, 0); 2540 g_detach(cp); 2541 g_destroy_consumer(cp); 2542} 2543 2544/* 2545 * Add a reference to the g_consumer for an inflight transaction. 2546 */ 2547static void 2548swapgeom_acquire(struct g_consumer *cp) 2549{ 2550 2551 mtx_assert(&sw_dev_mtx, MA_OWNED); 2552 cp->index++; 2553} 2554 2555/* 2556 * Remove a reference from the g_consumer. Post a close event if 2557 * all referneces go away. 2558 */ 2559static void 2560swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2561{ 2562 2563 mtx_assert(&sw_dev_mtx, MA_OWNED); 2564 cp->index--; 2565 if (cp->index == 0) { 2566 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2567 sp->sw_id = NULL; 2568 } 2569} 2570 2571static void 2572swapgeom_done(struct bio *bp2) 2573{ 2574 struct swdevt *sp; 2575 struct buf *bp; 2576 struct g_consumer *cp; 2577 2578 bp = bp2->bio_caller2; 2579 cp = bp2->bio_from; 2580 bp->b_ioflags = bp2->bio_flags; 2581 if (bp2->bio_error) 2582 bp->b_ioflags |= BIO_ERROR; 2583 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2584 bp->b_error = bp2->bio_error; 2585 bufdone(bp); 2586 sp = bp2->bio_caller1; 2587 mtx_lock(&sw_dev_mtx); 2588 swapgeom_release(cp, sp); 2589 mtx_unlock(&sw_dev_mtx); 2590 g_destroy_bio(bp2); 2591} 2592 2593static void 2594swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2595{ 2596 struct bio *bio; 2597 struct g_consumer *cp; 2598 2599 mtx_lock(&sw_dev_mtx); 2600 cp = sp->sw_id; 2601 if (cp == NULL) { 2602 mtx_unlock(&sw_dev_mtx); 2603 bp->b_error = ENXIO; 2604 bp->b_ioflags |= BIO_ERROR; 2605 bufdone(bp); 2606 return; 2607 } 2608 swapgeom_acquire(cp); 2609 mtx_unlock(&sw_dev_mtx); 2610 if (bp->b_iocmd == BIO_WRITE) 2611 bio = g_new_bio(); 2612 else 2613 bio = g_alloc_bio(); 2614 if (bio == NULL) { 2615 mtx_lock(&sw_dev_mtx); 2616 swapgeom_release(cp, sp); 2617 mtx_unlock(&sw_dev_mtx); 2618 bp->b_error = ENOMEM; 2619 bp->b_ioflags |= BIO_ERROR; 2620 bufdone(bp); 2621 return; 2622 } 2623 2624 bio->bio_caller1 = sp; 2625 bio->bio_caller2 = bp; 2626 bio->bio_cmd = bp->b_iocmd; 2627 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2628 bio->bio_length = bp->b_bcount; 2629 bio->bio_done = swapgeom_done; 2630 if ((bp->b_flags & B_UNMAPPED) != 0) { 2631 bio->bio_ma = bp->b_pages; 2632 bio->bio_data = unmapped_buf; 2633 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2634 bio->bio_ma_n = bp->b_npages; 2635 bio->bio_flags |= BIO_UNMAPPED; 2636 } else { 2637 bio->bio_data = bp->b_data; 2638 bio->bio_ma = NULL; 2639 } 2640 g_io_request(bio, cp); 2641 return; 2642} 2643 2644static void 2645swapgeom_orphan(struct g_consumer *cp) 2646{ 2647 struct swdevt *sp; 2648 int destroy; 2649 2650 mtx_lock(&sw_dev_mtx); 2651 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2652 if (sp->sw_id == cp) { 2653 sp->sw_flags |= SW_CLOSING; 2654 break; 2655 } 2656 } 2657 /* 2658 * Drop reference we were created with. Do directly since we're in a 2659 * special context where we don't have to queue the call to 2660 * swapgeom_close_ev(). 2661 */ 2662 cp->index--; 2663 destroy = ((sp != NULL) && (cp->index == 0)); 2664 if (destroy) 2665 sp->sw_id = NULL; 2666 mtx_unlock(&sw_dev_mtx); 2667 if (destroy) 2668 swapgeom_close_ev(cp, 0); 2669} 2670 2671static void 2672swapgeom_close(struct thread *td, struct swdevt *sw) 2673{ 2674 struct g_consumer *cp; 2675 2676 mtx_lock(&sw_dev_mtx); 2677 cp = sw->sw_id; 2678 sw->sw_id = NULL; 2679 mtx_unlock(&sw_dev_mtx); 2680 /* XXX: direct call when Giant untangled */ 2681 if (cp != NULL) 2682 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2683} 2684 2685 2686struct swh0h0 { 2687 struct cdev *dev; 2688 struct vnode *vp; 2689 int error; 2690}; 2691 2692static void 2693swapongeom_ev(void *arg, int flags) 2694{ 2695 struct swh0h0 *swh; 2696 struct g_provider *pp; 2697 struct g_consumer *cp; 2698 static struct g_geom *gp; 2699 struct swdevt *sp; 2700 u_long nblks; 2701 int error; 2702 2703 swh = arg; 2704 swh->error = 0; 2705 pp = g_dev_getprovider(swh->dev); 2706 if (pp == NULL) { 2707 swh->error = ENODEV; 2708 return; 2709 } 2710 mtx_lock(&sw_dev_mtx); 2711 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2712 cp = sp->sw_id; 2713 if (cp != NULL && cp->provider == pp) { 2714 mtx_unlock(&sw_dev_mtx); 2715 swh->error = EBUSY; 2716 return; 2717 } 2718 } 2719 mtx_unlock(&sw_dev_mtx); 2720 if (gp == NULL) 2721 gp = g_new_geomf(&g_swap_class, "swap"); 2722 cp = g_new_consumer(gp); 2723 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2724 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2725 g_attach(cp, pp); 2726 /* 2727 * XXX: Everytime you think you can improve the margin for 2728 * footshooting, somebody depends on the ability to do so: 2729 * savecore(8) wants to write to our swapdev so we cannot 2730 * set an exclusive count :-( 2731 */ 2732 error = g_access(cp, 1, 1, 0); 2733 if (error) { 2734 g_detach(cp); 2735 g_destroy_consumer(cp); 2736 swh->error = error; 2737 return; 2738 } 2739 nblks = pp->mediasize / DEV_BSIZE; 2740 swaponsomething(swh->vp, cp, nblks, swapgeom_strategy, 2741 swapgeom_close, dev2udev(swh->dev), 2742 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2743 swh->error = 0; 2744} 2745 2746static int 2747swapongeom(struct thread *td, struct vnode *vp) 2748{ 2749 int error; 2750 struct swh0h0 swh; 2751 2752 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2753 2754 swh.dev = vp->v_rdev; 2755 swh.vp = vp; 2756 swh.error = 0; 2757 /* XXX: direct call when Giant untangled */ 2758 error = g_waitfor_event(swapongeom_ev, &swh, M_WAITOK, NULL); 2759 if (!error) 2760 error = swh.error; 2761 VOP_UNLOCK(vp, 0); 2762 return (error); 2763} 2764 2765/* 2766 * VNODE backend 2767 * 2768 * This is used mainly for network filesystem (read: probably only tested 2769 * with NFS) swapfiles. 2770 * 2771 */ 2772 2773static void 2774swapdev_strategy(struct buf *bp, struct swdevt *sp) 2775{ 2776 struct vnode *vp2; 2777 2778 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2779 2780 vp2 = sp->sw_id; 2781 vhold(vp2); 2782 if (bp->b_iocmd == BIO_WRITE) { 2783 if (bp->b_bufobj) 2784 bufobj_wdrop(bp->b_bufobj); 2785 bufobj_wref(&vp2->v_bufobj); 2786 } 2787 if (bp->b_bufobj != &vp2->v_bufobj) 2788 bp->b_bufobj = &vp2->v_bufobj; 2789 bp->b_vp = vp2; 2790 bp->b_iooffset = dbtob(bp->b_blkno); 2791 bstrategy(bp); 2792 return; 2793} 2794 2795static void 2796swapdev_close(struct thread *td, struct swdevt *sp) 2797{ 2798 2799 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2800 vrele(sp->sw_vp); 2801} 2802 2803 2804static int 2805swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2806{ 2807 struct swdevt *sp; 2808 int error; 2809 2810 if (nblks == 0) 2811 return (ENXIO); 2812 mtx_lock(&sw_dev_mtx); 2813 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2814 if (sp->sw_id == vp) { 2815 mtx_unlock(&sw_dev_mtx); 2816 return (EBUSY); 2817 } 2818 } 2819 mtx_unlock(&sw_dev_mtx); 2820 2821 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2822#ifdef MAC 2823 error = mac_system_check_swapon(td->td_ucred, vp); 2824 if (error == 0) 2825#endif 2826 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 2827 (void) VOP_UNLOCK(vp, 0); 2828 if (error) 2829 return (error); 2830 2831 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 2832 NODEV, 0); 2833 return (0); 2834} 2835