swap_pager.c revision 305803
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 305803 2016-09-14 10:51:06Z kib $"); 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 * SWB_NPAGES must be a power of 2. It may be set to 1, 2, 4, 8, 16 119 * or 32 pages per allocation. 120 * The 32-page limit is due to the radix code (kern/subr_blist.c). 121 */ 122#ifndef MAX_PAGEOUT_CLUSTER 123#define MAX_PAGEOUT_CLUSTER 16 124#endif 125 126#if !defined(SWB_NPAGES) 127#define SWB_NPAGES MAX_PAGEOUT_CLUSTER 128#endif 129 130/* 131 * The swblock structure maps an object and a small, fixed-size range 132 * of page indices to disk addresses within a swap area. 133 * The collection of these mappings is implemented as a hash table. 134 * Unused disk addresses within a swap area are allocated and managed 135 * using a blist. 136 */ 137#define SWCORRECT(n) (sizeof(void *) * (n) / sizeof(daddr_t)) 138#define SWAP_META_PAGES (SWB_NPAGES * 2) 139#define SWAP_META_MASK (SWAP_META_PAGES - 1) 140 141struct swblock { 142 struct swblock *swb_hnext; 143 vm_object_t swb_object; 144 vm_pindex_t swb_index; 145 int swb_count; 146 daddr_t swb_pages[SWAP_META_PAGES]; 147}; 148 149static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); 150static struct mtx sw_dev_mtx; 151static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 152static struct swdevt *swdevhd; /* Allocate from here next */ 153static int nswapdev; /* Number of swap devices */ 154int swap_pager_avail; 155static int swdev_syscall_active = 0; /* serialize swap(on|off) */ 156 157static vm_ooffset_t swap_total; 158SYSCTL_QUAD(_vm, OID_AUTO, swap_total, CTLFLAG_RD, &swap_total, 0, 159 "Total amount of available swap storage."); 160static vm_ooffset_t swap_reserved; 161SYSCTL_QUAD(_vm, OID_AUTO, swap_reserved, CTLFLAG_RD, &swap_reserved, 0, 162 "Amount of swap storage needed to back all allocated anonymous memory."); 163static int overcommit = 0; 164SYSCTL_INT(_vm, OID_AUTO, overcommit, CTLFLAG_RW, &overcommit, 0, 165 "Configure virtual memory overcommit behavior. See tuning(7) " 166 "for details."); 167static unsigned long swzone; 168SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 169 "Actual size of swap metadata zone"); 170static unsigned long swap_maxpages; 171SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, 172 "Maximum amount of swap supported"); 173 174/* bits from overcommit */ 175#define SWAP_RESERVE_FORCE_ON (1 << 0) 176#define SWAP_RESERVE_RLIMIT_ON (1 << 1) 177#define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2) 178 179int 180swap_reserve(vm_ooffset_t incr) 181{ 182 183 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 184} 185 186int 187swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 188{ 189 vm_ooffset_t r, s; 190 int res, error; 191 static int curfail; 192 static struct timeval lastfail; 193 struct uidinfo *uip; 194 195 uip = cred->cr_ruidinfo; 196 197 if (incr & PAGE_MASK) 198 panic("swap_reserve: & PAGE_MASK"); 199 200#ifdef RACCT 201 if (racct_enable) { 202 PROC_LOCK(curproc); 203 error = racct_add(curproc, RACCT_SWAP, incr); 204 PROC_UNLOCK(curproc); 205 if (error != 0) 206 return (0); 207 } 208#endif 209 210 res = 0; 211 mtx_lock(&sw_dev_mtx); 212 r = swap_reserved + incr; 213 if (overcommit & SWAP_RESERVE_ALLOW_NONWIRED) { 214 s = cnt.v_page_count - cnt.v_free_reserved - cnt.v_wire_count; 215 s *= PAGE_SIZE; 216 } else 217 s = 0; 218 s += swap_total; 219 if ((overcommit & SWAP_RESERVE_FORCE_ON) == 0 || r <= s || 220 (error = priv_check(curthread, PRIV_VM_SWAP_NOQUOTA)) == 0) { 221 res = 1; 222 swap_reserved = r; 223 } 224 mtx_unlock(&sw_dev_mtx); 225 226 if (res) { 227 PROC_LOCK(curproc); 228 UIDINFO_VMSIZE_LOCK(uip); 229 if ((overcommit & SWAP_RESERVE_RLIMIT_ON) != 0 && 230 uip->ui_vmsize + incr > lim_cur(curproc, RLIMIT_SWAP) && 231 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT)) 232 res = 0; 233 else 234 uip->ui_vmsize += incr; 235 UIDINFO_VMSIZE_UNLOCK(uip); 236 PROC_UNLOCK(curproc); 237 if (!res) { 238 mtx_lock(&sw_dev_mtx); 239 swap_reserved -= incr; 240 mtx_unlock(&sw_dev_mtx); 241 } 242 } 243 if (!res && ppsratecheck(&lastfail, &curfail, 1)) { 244 printf("uid %d, pid %d: swap reservation for %jd bytes failed\n", 245 uip->ui_uid, curproc->p_pid, incr); 246 } 247 248#ifdef RACCT 249 if (!res) { 250 PROC_LOCK(curproc); 251 racct_sub(curproc, RACCT_SWAP, incr); 252 PROC_UNLOCK(curproc); 253 } 254#endif 255 256 return (res); 257} 258 259void 260swap_reserve_force(vm_ooffset_t incr) 261{ 262 struct uidinfo *uip; 263 264 mtx_lock(&sw_dev_mtx); 265 swap_reserved += incr; 266 mtx_unlock(&sw_dev_mtx); 267 268#ifdef RACCT 269 PROC_LOCK(curproc); 270 racct_add_force(curproc, RACCT_SWAP, incr); 271 PROC_UNLOCK(curproc); 272#endif 273 274 uip = curthread->td_ucred->cr_ruidinfo; 275 PROC_LOCK(curproc); 276 UIDINFO_VMSIZE_LOCK(uip); 277 uip->ui_vmsize += incr; 278 UIDINFO_VMSIZE_UNLOCK(uip); 279 PROC_UNLOCK(curproc); 280} 281 282void 283swap_release(vm_ooffset_t decr) 284{ 285 struct ucred *cred; 286 287 PROC_LOCK(curproc); 288 cred = curthread->td_ucred; 289 swap_release_by_cred(decr, cred); 290 PROC_UNLOCK(curproc); 291} 292 293void 294swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 295{ 296 struct uidinfo *uip; 297 298 uip = cred->cr_ruidinfo; 299 300 if (decr & PAGE_MASK) 301 panic("swap_release: & PAGE_MASK"); 302 303 mtx_lock(&sw_dev_mtx); 304 if (swap_reserved < decr) 305 panic("swap_reserved < decr"); 306 swap_reserved -= decr; 307 mtx_unlock(&sw_dev_mtx); 308 309 UIDINFO_VMSIZE_LOCK(uip); 310 if (uip->ui_vmsize < decr) 311 printf("negative vmsize for uid = %d\n", uip->ui_uid); 312 uip->ui_vmsize -= decr; 313 UIDINFO_VMSIZE_UNLOCK(uip); 314 315 racct_sub_cred(cred, RACCT_SWAP, decr); 316} 317 318static void swapdev_strategy(struct buf *, struct swdevt *sw); 319 320#define SWM_FREE 0x02 /* free, period */ 321#define SWM_POP 0x04 /* pop out */ 322 323int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 324static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 325static int nsw_rcount; /* free read buffers */ 326static int nsw_wcount_sync; /* limit write buffers / synchronous */ 327static int nsw_wcount_async; /* limit write buffers / asynchronous */ 328static int nsw_wcount_async_max;/* assigned maximum */ 329static int nsw_cluster_max; /* maximum VOP I/O allowed */ 330 331static struct swblock **swhash; 332static int swhash_mask; 333static struct mtx swhash_mtx; 334 335static int swap_async_max = 4; /* maximum in-progress async I/O's */ 336static struct sx sw_alloc_sx; 337 338 339SYSCTL_INT(_vm, OID_AUTO, swap_async_max, 340 CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops"); 341 342/* 343 * "named" and "unnamed" anon region objects. Try to reduce the overhead 344 * of searching a named list by hashing it just a little. 345 */ 346 347#define NOBJLISTS 8 348 349#define NOBJLIST(handle) \ 350 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 351 352static struct mtx sw_alloc_mtx; /* protect list manipulation */ 353static struct pagerlst swap_pager_object_list[NOBJLISTS]; 354static uma_zone_t swap_zone; 355 356/* 357 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 358 * calls hooked from other parts of the VM system and do not appear here. 359 * (see vm/swap_pager.h). 360 */ 361static vm_object_t 362 swap_pager_alloc(void *handle, vm_ooffset_t size, 363 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 364static void swap_pager_dealloc(vm_object_t object); 365static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int); 366static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 367static boolean_t 368 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 369static void swap_pager_init(void); 370static void swap_pager_unswapped(vm_page_t); 371static void swap_pager_swapoff(struct swdevt *sp); 372 373struct pagerops swappagerops = { 374 .pgo_init = swap_pager_init, /* early system initialization of pager */ 375 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 376 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 377 .pgo_getpages = swap_pager_getpages, /* pagein */ 378 .pgo_putpages = swap_pager_putpages, /* pageout */ 379 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 380 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 381}; 382 383/* 384 * dmmax is in page-sized chunks with the new swap system. It was 385 * dev-bsized chunks in the old. dmmax is always a power of 2. 386 * 387 * swap_*() routines are externally accessible. swp_*() routines are 388 * internal. 389 */ 390static int dmmax; 391static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 392static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 393 394SYSCTL_INT(_vm, OID_AUTO, dmmax, 395 CTLFLAG_RD, &dmmax, 0, "Maximum size of a swap block"); 396 397static void swp_sizecheck(void); 398static void swp_pager_async_iodone(struct buf *bp); 399static int swapongeom(struct thread *, struct vnode *); 400static int swaponvp(struct thread *, struct vnode *, u_long); 401static int swapoff_one(struct swdevt *sp, struct ucred *cred); 402 403/* 404 * Swap bitmap functions 405 */ 406static void swp_pager_freeswapspace(daddr_t blk, int npages); 407static daddr_t swp_pager_getswapspace(int npages); 408 409/* 410 * Metadata functions 411 */ 412static struct swblock **swp_pager_hash(vm_object_t object, vm_pindex_t index); 413static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 414static void swp_pager_meta_free(vm_object_t, vm_pindex_t, daddr_t); 415static void swp_pager_meta_free_all(vm_object_t); 416static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 417 418static void 419swp_pager_free_nrpage(vm_page_t m) 420{ 421 422 vm_page_lock(m); 423 if (m->wire_count == 0) 424 vm_page_free(m); 425 vm_page_unlock(m); 426} 427 428/* 429 * SWP_SIZECHECK() - update swap_pager_full indication 430 * 431 * update the swap_pager_almost_full indication and warn when we are 432 * about to run out of swap space, using lowat/hiwat hysteresis. 433 * 434 * Clear swap_pager_full ( task killing ) indication when lowat is met. 435 * 436 * No restrictions on call 437 * This routine may not block. 438 */ 439static void 440swp_sizecheck(void) 441{ 442 443 if (swap_pager_avail < nswap_lowat) { 444 if (swap_pager_almost_full == 0) { 445 printf("swap_pager: out of swap space\n"); 446 swap_pager_almost_full = 1; 447 } 448 } else { 449 swap_pager_full = 0; 450 if (swap_pager_avail > nswap_hiwat) 451 swap_pager_almost_full = 0; 452 } 453} 454 455/* 456 * SWP_PAGER_HASH() - hash swap meta data 457 * 458 * This is an helper function which hashes the swapblk given 459 * the object and page index. It returns a pointer to a pointer 460 * to the object, or a pointer to a NULL pointer if it could not 461 * find a swapblk. 462 */ 463static struct swblock ** 464swp_pager_hash(vm_object_t object, vm_pindex_t index) 465{ 466 struct swblock **pswap; 467 struct swblock *swap; 468 469 index &= ~(vm_pindex_t)SWAP_META_MASK; 470 pswap = &swhash[(index ^ (int)(intptr_t)object) & swhash_mask]; 471 while ((swap = *pswap) != NULL) { 472 if (swap->swb_object == object && 473 swap->swb_index == index 474 ) { 475 break; 476 } 477 pswap = &swap->swb_hnext; 478 } 479 return (pswap); 480} 481 482/* 483 * SWAP_PAGER_INIT() - initialize the swap pager! 484 * 485 * Expected to be started from system init. NOTE: This code is run 486 * before much else so be careful what you depend on. Most of the VM 487 * system has yet to be initialized at this point. 488 */ 489static void 490swap_pager_init(void) 491{ 492 /* 493 * Initialize object lists 494 */ 495 int i; 496 497 for (i = 0; i < NOBJLISTS; ++i) 498 TAILQ_INIT(&swap_pager_object_list[i]); 499 mtx_init(&sw_alloc_mtx, "swap_pager list", NULL, MTX_DEF); 500 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 501 sx_init(&sw_alloc_sx, "swspsx"); 502 503 /* 504 * Device Stripe, in PAGE_SIZE'd blocks 505 */ 506 dmmax = SWB_NPAGES * 2; 507} 508 509/* 510 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 511 * 512 * Expected to be started from pageout process once, prior to entering 513 * its main loop. 514 */ 515void 516swap_pager_swap_init(void) 517{ 518 unsigned long n, n2; 519 520 /* 521 * Number of in-transit swap bp operations. Don't 522 * exhaust the pbufs completely. Make sure we 523 * initialize workable values (0 will work for hysteresis 524 * but it isn't very efficient). 525 * 526 * The nsw_cluster_max is constrained by the bp->b_pages[] 527 * array (MAXPHYS/PAGE_SIZE) and our locally defined 528 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 529 * constrained by the swap device interleave stripe size. 530 * 531 * Currently we hardwire nsw_wcount_async to 4. This limit is 532 * designed to prevent other I/O from having high latencies due to 533 * our pageout I/O. The value 4 works well for one or two active swap 534 * devices but is probably a little low if you have more. Even so, 535 * a higher value would probably generate only a limited improvement 536 * with three or four active swap devices since the system does not 537 * typically have to pageout at extreme bandwidths. We will want 538 * at least 2 per swap devices, and 4 is a pretty good value if you 539 * have one NFS swap device due to the command/ack latency over NFS. 540 * So it all works out pretty well. 541 */ 542 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER); 543 544 mtx_lock(&pbuf_mtx); 545 nsw_rcount = (nswbuf + 1) / 2; 546 nsw_wcount_sync = (nswbuf + 3) / 4; 547 nsw_wcount_async = 4; 548 nsw_wcount_async_max = nsw_wcount_async; 549 mtx_unlock(&pbuf_mtx); 550 551 /* 552 * Initialize our zone. Right now I'm just guessing on the number 553 * we need based on the number of pages in the system. Each swblock 554 * can hold 32 pages, so this is probably overkill. This reservation 555 * is typically limited to around 32MB by default. 556 */ 557 n = cnt.v_page_count / 2; 558 if (maxswzone && n > maxswzone / sizeof(struct swblock)) 559 n = maxswzone / sizeof(struct swblock); 560 n2 = n; 561 swap_zone = uma_zcreate("SWAPMETA", sizeof(struct swblock), NULL, NULL, 562 NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE | UMA_ZONE_VM); 563 if (swap_zone == NULL) 564 panic("failed to create swap_zone."); 565 do { 566 if (uma_zone_reserve_kva(swap_zone, n)) 567 break; 568 /* 569 * if the allocation failed, try a zone two thirds the 570 * size of the previous attempt. 571 */ 572 n -= ((n + 2) / 3); 573 } while (n > 0); 574 if (n2 != n) 575 printf("Swap zone entries reduced from %lu to %lu.\n", n2, n); 576 swap_maxpages = n * SWAP_META_PAGES; 577 swzone = n * sizeof(struct swblock); 578 n2 = n; 579 580 /* 581 * Initialize our meta-data hash table. The swapper does not need to 582 * be quite as efficient as the VM system, so we do not use an 583 * oversized hash table. 584 * 585 * n: size of hash table, must be power of 2 586 * swhash_mask: hash table index mask 587 */ 588 for (n = 1; n < n2 / 8; n *= 2) 589 ; 590 swhash = malloc(sizeof(struct swblock *) * n, M_VMPGDATA, M_WAITOK | M_ZERO); 591 swhash_mask = n - 1; 592 mtx_init(&swhash_mtx, "swap_pager swhash", NULL, MTX_DEF); 593} 594 595/* 596 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 597 * its metadata structures. 598 * 599 * This routine is called from the mmap and fork code to create a new 600 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object 601 * and then converting it with swp_pager_meta_build(). 602 * 603 * This routine may block in vm_object_allocate() and create a named 604 * object lookup race, so we must interlock. 605 * 606 * MPSAFE 607 */ 608static vm_object_t 609swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 610 vm_ooffset_t offset, struct ucred *cred) 611{ 612 vm_object_t object; 613 vm_pindex_t pindex; 614 615 pindex = OFF_TO_IDX(offset + PAGE_MASK + size); 616 if (handle) { 617 mtx_lock(&Giant); 618 /* 619 * Reference existing named region or allocate new one. There 620 * should not be a race here against swp_pager_meta_build() 621 * as called from vm_page_remove() in regards to the lookup 622 * of the handle. 623 */ 624 sx_xlock(&sw_alloc_sx); 625 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 626 if (object == NULL) { 627 if (cred != NULL) { 628 if (!swap_reserve_by_cred(size, cred)) { 629 sx_xunlock(&sw_alloc_sx); 630 mtx_unlock(&Giant); 631 return (NULL); 632 } 633 crhold(cred); 634 } 635 object = vm_object_allocate(OBJT_DEFAULT, pindex); 636 VM_OBJECT_WLOCK(object); 637 object->handle = handle; 638 if (cred != NULL) { 639 object->cred = cred; 640 object->charge = size; 641 } 642 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 643 VM_OBJECT_WUNLOCK(object); 644 } 645 sx_xunlock(&sw_alloc_sx); 646 mtx_unlock(&Giant); 647 } else { 648 if (cred != NULL) { 649 if (!swap_reserve_by_cred(size, cred)) 650 return (NULL); 651 crhold(cred); 652 } 653 object = vm_object_allocate(OBJT_DEFAULT, pindex); 654 VM_OBJECT_WLOCK(object); 655 if (cred != NULL) { 656 object->cred = cred; 657 object->charge = size; 658 } 659 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 660 VM_OBJECT_WUNLOCK(object); 661 } 662 return (object); 663} 664 665/* 666 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 667 * 668 * The swap backing for the object is destroyed. The code is 669 * designed such that we can reinstantiate it later, but this 670 * routine is typically called only when the entire object is 671 * about to be destroyed. 672 * 673 * The object must be locked. 674 */ 675static void 676swap_pager_dealloc(vm_object_t object) 677{ 678 679 /* 680 * Remove from list right away so lookups will fail if we block for 681 * pageout completion. 682 */ 683 if (object->handle != NULL) { 684 mtx_lock(&sw_alloc_mtx); 685 TAILQ_REMOVE(NOBJLIST(object->handle), object, pager_object_list); 686 mtx_unlock(&sw_alloc_mtx); 687 } 688 689 VM_OBJECT_ASSERT_WLOCKED(object); 690 vm_object_pip_wait(object, "swpdea"); 691 692 /* 693 * Free all remaining metadata. We only bother to free it from 694 * the swap meta data. We do not attempt to free swapblk's still 695 * associated with vm_page_t's for this object. We do not care 696 * if paging is still in progress on some objects. 697 */ 698 swp_pager_meta_free_all(object); 699 object->handle = NULL; 700 object->type = OBJT_DEAD; 701} 702 703/************************************************************************ 704 * SWAP PAGER BITMAP ROUTINES * 705 ************************************************************************/ 706 707/* 708 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 709 * 710 * Allocate swap for the requested number of pages. The starting 711 * swap block number (a page index) is returned or SWAPBLK_NONE 712 * if the allocation failed. 713 * 714 * Also has the side effect of advising that somebody made a mistake 715 * when they configured swap and didn't configure enough. 716 * 717 * This routine may not sleep. 718 * 719 * We allocate in round-robin fashion from the configured devices. 720 */ 721static daddr_t 722swp_pager_getswapspace(int npages) 723{ 724 daddr_t blk; 725 struct swdevt *sp; 726 int i; 727 728 blk = SWAPBLK_NONE; 729 mtx_lock(&sw_dev_mtx); 730 sp = swdevhd; 731 for (i = 0; i < nswapdev; i++) { 732 if (sp == NULL) 733 sp = TAILQ_FIRST(&swtailq); 734 if (!(sp->sw_flags & SW_CLOSING)) { 735 blk = blist_alloc(sp->sw_blist, npages); 736 if (blk != SWAPBLK_NONE) { 737 blk += sp->sw_first; 738 sp->sw_used += npages; 739 swap_pager_avail -= npages; 740 swp_sizecheck(); 741 swdevhd = TAILQ_NEXT(sp, sw_list); 742 goto done; 743 } 744 } 745 sp = TAILQ_NEXT(sp, sw_list); 746 } 747 if (swap_pager_full != 2) { 748 printf("swap_pager_getswapspace(%d): failed\n", npages); 749 swap_pager_full = 2; 750 swap_pager_almost_full = 1; 751 } 752 swdevhd = NULL; 753done: 754 mtx_unlock(&sw_dev_mtx); 755 return (blk); 756} 757 758static int 759swp_pager_isondev(daddr_t blk, struct swdevt *sp) 760{ 761 762 return (blk >= sp->sw_first && blk < sp->sw_end); 763} 764 765static void 766swp_pager_strategy(struct buf *bp) 767{ 768 struct swdevt *sp; 769 770 mtx_lock(&sw_dev_mtx); 771 TAILQ_FOREACH(sp, &swtailq, sw_list) { 772 if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) { 773 mtx_unlock(&sw_dev_mtx); 774 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 775 unmapped_buf_allowed) { 776 bp->b_kvaalloc = bp->b_data; 777 bp->b_data = unmapped_buf; 778 bp->b_kvabase = unmapped_buf; 779 bp->b_offset = 0; 780 bp->b_flags |= B_UNMAPPED; 781 } else { 782 pmap_qenter((vm_offset_t)bp->b_data, 783 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 784 } 785 sp->sw_strategy(bp, sp); 786 return; 787 } 788 } 789 panic("Swapdev not found"); 790} 791 792 793/* 794 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 795 * 796 * This routine returns the specified swap blocks back to the bitmap. 797 * 798 * This routine may not sleep. 799 */ 800static void 801swp_pager_freeswapspace(daddr_t blk, int npages) 802{ 803 struct swdevt *sp; 804 805 mtx_lock(&sw_dev_mtx); 806 TAILQ_FOREACH(sp, &swtailq, sw_list) { 807 if (blk >= sp->sw_first && blk < sp->sw_end) { 808 sp->sw_used -= npages; 809 /* 810 * If we are attempting to stop swapping on 811 * this device, we don't want to mark any 812 * blocks free lest they be reused. 813 */ 814 if ((sp->sw_flags & SW_CLOSING) == 0) { 815 blist_free(sp->sw_blist, blk - sp->sw_first, 816 npages); 817 swap_pager_avail += npages; 818 swp_sizecheck(); 819 } 820 mtx_unlock(&sw_dev_mtx); 821 return; 822 } 823 } 824 panic("Swapdev not found"); 825} 826 827/* 828 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 829 * range within an object. 830 * 831 * This is a globally accessible routine. 832 * 833 * This routine removes swapblk assignments from swap metadata. 834 * 835 * The external callers of this routine typically have already destroyed 836 * or renamed vm_page_t's associated with this range in the object so 837 * we should be ok. 838 * 839 * The object must be locked. 840 */ 841void 842swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 843{ 844 845 swp_pager_meta_free(object, start, size); 846} 847 848/* 849 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 850 * 851 * Assigns swap blocks to the specified range within the object. The 852 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 853 * 854 * Returns 0 on success, -1 on failure. 855 */ 856int 857swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 858{ 859 int n = 0; 860 daddr_t blk = SWAPBLK_NONE; 861 vm_pindex_t beg = start; /* save start index */ 862 863 VM_OBJECT_WLOCK(object); 864 while (size) { 865 if (n == 0) { 866 n = BLIST_MAX_ALLOC; 867 while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) { 868 n >>= 1; 869 if (n == 0) { 870 swp_pager_meta_free(object, beg, start - beg); 871 VM_OBJECT_WUNLOCK(object); 872 return (-1); 873 } 874 } 875 } 876 swp_pager_meta_build(object, start, blk); 877 --size; 878 ++start; 879 ++blk; 880 --n; 881 } 882 swp_pager_meta_free(object, start, n); 883 VM_OBJECT_WUNLOCK(object); 884 return (0); 885} 886 887/* 888 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 889 * and destroy the source. 890 * 891 * Copy any valid swapblks from the source to the destination. In 892 * cases where both the source and destination have a valid swapblk, 893 * we keep the destination's. 894 * 895 * This routine is allowed to sleep. It may sleep allocating metadata 896 * indirectly through swp_pager_meta_build() or if paging is still in 897 * progress on the source. 898 * 899 * The source object contains no vm_page_t's (which is just as well) 900 * 901 * The source object is of type OBJT_SWAP. 902 * 903 * The source and destination objects must be locked. 904 * Both object locks may temporarily be released. 905 */ 906void 907swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 908 vm_pindex_t offset, int destroysource) 909{ 910 vm_pindex_t i; 911 912 VM_OBJECT_ASSERT_WLOCKED(srcobject); 913 VM_OBJECT_ASSERT_WLOCKED(dstobject); 914 915 /* 916 * If destroysource is set, we remove the source object from the 917 * swap_pager internal queue now. 918 */ 919 if (destroysource) { 920 if (srcobject->handle != NULL) { 921 mtx_lock(&sw_alloc_mtx); 922 TAILQ_REMOVE( 923 NOBJLIST(srcobject->handle), 924 srcobject, 925 pager_object_list 926 ); 927 mtx_unlock(&sw_alloc_mtx); 928 } 929 } 930 931 /* 932 * transfer source to destination. 933 */ 934 for (i = 0; i < dstobject->size; ++i) { 935 daddr_t dstaddr; 936 937 /* 938 * Locate (without changing) the swapblk on the destination, 939 * unless it is invalid in which case free it silently, or 940 * if the destination is a resident page, in which case the 941 * source is thrown away. 942 */ 943 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 944 945 if (dstaddr == SWAPBLK_NONE) { 946 /* 947 * Destination has no swapblk and is not resident, 948 * copy source. 949 */ 950 daddr_t srcaddr; 951 952 srcaddr = swp_pager_meta_ctl( 953 srcobject, 954 i + offset, 955 SWM_POP 956 ); 957 958 if (srcaddr != SWAPBLK_NONE) { 959 /* 960 * swp_pager_meta_build() can sleep. 961 */ 962 vm_object_pip_add(srcobject, 1); 963 VM_OBJECT_WUNLOCK(srcobject); 964 vm_object_pip_add(dstobject, 1); 965 swp_pager_meta_build(dstobject, i, srcaddr); 966 vm_object_pip_wakeup(dstobject); 967 VM_OBJECT_WLOCK(srcobject); 968 vm_object_pip_wakeup(srcobject); 969 } 970 } else { 971 /* 972 * Destination has valid swapblk or it is represented 973 * by a resident page. We destroy the sourceblock. 974 */ 975 976 swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE); 977 } 978 } 979 980 /* 981 * Free left over swap blocks in source. 982 * 983 * We have to revert the type to OBJT_DEFAULT so we do not accidently 984 * double-remove the object from the swap queues. 985 */ 986 if (destroysource) { 987 swp_pager_meta_free_all(srcobject); 988 /* 989 * Reverting the type is not necessary, the caller is going 990 * to destroy srcobject directly, but I'm doing it here 991 * for consistency since we've removed the object from its 992 * queues. 993 */ 994 srcobject->type = OBJT_DEFAULT; 995 } 996} 997 998/* 999 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1000 * the requested page. 1001 * 1002 * We determine whether good backing store exists for the requested 1003 * page and return TRUE if it does, FALSE if it doesn't. 1004 * 1005 * If TRUE, we also try to determine how much valid, contiguous backing 1006 * store exists before and after the requested page within a reasonable 1007 * distance. We do not try to restrict it to the swap device stripe 1008 * (that is handled in getpages/putpages). It probably isn't worth 1009 * doing here. 1010 */ 1011static boolean_t 1012swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after) 1013{ 1014 daddr_t blk0; 1015 1016 VM_OBJECT_ASSERT_LOCKED(object); 1017 /* 1018 * do we have good backing store at the requested index ? 1019 */ 1020 blk0 = swp_pager_meta_ctl(object, pindex, 0); 1021 1022 if (blk0 == SWAPBLK_NONE) { 1023 if (before) 1024 *before = 0; 1025 if (after) 1026 *after = 0; 1027 return (FALSE); 1028 } 1029 1030 /* 1031 * find backwards-looking contiguous good backing store 1032 */ 1033 if (before != NULL) { 1034 int i; 1035 1036 for (i = 1; i < (SWB_NPAGES/2); ++i) { 1037 daddr_t blk; 1038 1039 if (i > pindex) 1040 break; 1041 blk = swp_pager_meta_ctl(object, pindex - i, 0); 1042 if (blk != blk0 - i) 1043 break; 1044 } 1045 *before = (i - 1); 1046 } 1047 1048 /* 1049 * find forward-looking contiguous good backing store 1050 */ 1051 if (after != NULL) { 1052 int i; 1053 1054 for (i = 1; i < (SWB_NPAGES/2); ++i) { 1055 daddr_t blk; 1056 1057 blk = swp_pager_meta_ctl(object, pindex + i, 0); 1058 if (blk != blk0 + i) 1059 break; 1060 } 1061 *after = (i - 1); 1062 } 1063 return (TRUE); 1064} 1065 1066/* 1067 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1068 * 1069 * This removes any associated swap backing store, whether valid or 1070 * not, from the page. 1071 * 1072 * This routine is typically called when a page is made dirty, at 1073 * which point any associated swap can be freed. MADV_FREE also 1074 * calls us in a special-case situation 1075 * 1076 * NOTE!!! If the page is clean and the swap was valid, the caller 1077 * should make the page dirty before calling this routine. This routine 1078 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1079 * depends on it. 1080 * 1081 * This routine may not sleep. 1082 * 1083 * The object containing the page must be locked. 1084 */ 1085static void 1086swap_pager_unswapped(vm_page_t m) 1087{ 1088 1089 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); 1090} 1091 1092/* 1093 * SWAP_PAGER_GETPAGES() - bring pages in from swap 1094 * 1095 * Attempt to retrieve (m, count) pages from backing store, but make 1096 * sure we retrieve at least m[reqpage]. We try to load in as large 1097 * a chunk surrounding m[reqpage] as is contiguous in swap and which 1098 * belongs to the same object. 1099 * 1100 * The code is designed for asynchronous operation and 1101 * immediate-notification of 'reqpage' but tends not to be 1102 * used that way. Please do not optimize-out this algorithmic 1103 * feature, I intend to improve on it in the future. 1104 * 1105 * The parent has a single vm_object_pip_add() reference prior to 1106 * calling us and we should return with the same. 1107 * 1108 * The parent has BUSY'd the pages. We should return with 'm' 1109 * left busy, but the others adjusted. 1110 */ 1111static int 1112swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage) 1113{ 1114 struct buf *bp; 1115 vm_page_t mreq; 1116 int i; 1117 int j; 1118 daddr_t blk; 1119 1120 mreq = m[reqpage]; 1121 1122 KASSERT(mreq->object == object, 1123 ("swap_pager_getpages: object mismatch %p/%p", 1124 object, mreq->object)); 1125 1126 /* 1127 * Calculate range to retrieve. The pages have already been assigned 1128 * their swapblks. We require a *contiguous* range but we know it to 1129 * not span devices. If we do not supply it, bad things 1130 * happen. Note that blk, iblk & jblk can be SWAPBLK_NONE, but the 1131 * loops are set up such that the case(s) are handled implicitly. 1132 * 1133 * The swp_*() calls must be made with the object locked. 1134 */ 1135 blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0); 1136 1137 for (i = reqpage - 1; i >= 0; --i) { 1138 daddr_t iblk; 1139 1140 iblk = swp_pager_meta_ctl(m[i]->object, m[i]->pindex, 0); 1141 if (blk != iblk + (reqpage - i)) 1142 break; 1143 } 1144 ++i; 1145 1146 for (j = reqpage + 1; j < count; ++j) { 1147 daddr_t jblk; 1148 1149 jblk = swp_pager_meta_ctl(m[j]->object, m[j]->pindex, 0); 1150 if (blk != jblk - (j - reqpage)) 1151 break; 1152 } 1153 1154 /* 1155 * free pages outside our collection range. Note: we never free 1156 * mreq, it must remain busy throughout. 1157 */ 1158 if (0 < i || j < count) { 1159 int k; 1160 1161 for (k = 0; k < i; ++k) 1162 swp_pager_free_nrpage(m[k]); 1163 for (k = j; k < count; ++k) 1164 swp_pager_free_nrpage(m[k]); 1165 } 1166 1167 /* 1168 * Return VM_PAGER_FAIL if we have nothing to do. Return mreq 1169 * still busy, but the others unbusied. 1170 */ 1171 if (blk == SWAPBLK_NONE) 1172 return (VM_PAGER_FAIL); 1173 1174 /* 1175 * Getpbuf() can sleep. 1176 */ 1177 VM_OBJECT_WUNLOCK(object); 1178 /* 1179 * Get a swap buffer header to perform the IO 1180 */ 1181 bp = getpbuf(&nsw_rcount); 1182 bp->b_flags |= B_PAGING; 1183 1184 bp->b_iocmd = BIO_READ; 1185 bp->b_iodone = swp_pager_async_iodone; 1186 bp->b_rcred = crhold(thread0.td_ucred); 1187 bp->b_wcred = crhold(thread0.td_ucred); 1188 bp->b_blkno = blk - (reqpage - i); 1189 bp->b_bcount = PAGE_SIZE * (j - i); 1190 bp->b_bufsize = PAGE_SIZE * (j - i); 1191 bp->b_pager.pg_reqpage = reqpage - i; 1192 1193 VM_OBJECT_WLOCK(object); 1194 { 1195 int k; 1196 1197 for (k = i; k < j; ++k) { 1198 bp->b_pages[k - i] = m[k]; 1199 m[k]->oflags |= VPO_SWAPINPROG; 1200 } 1201 } 1202 bp->b_npages = j - i; 1203 1204 PCPU_INC(cnt.v_swapin); 1205 PCPU_ADD(cnt.v_swappgsin, bp->b_npages); 1206 1207 /* 1208 * We still hold the lock on mreq, and our automatic completion routine 1209 * does not remove it. 1210 */ 1211 vm_object_pip_add(object, bp->b_npages); 1212 VM_OBJECT_WUNLOCK(object); 1213 1214 /* 1215 * perform the I/O. NOTE!!! bp cannot be considered valid after 1216 * this point because we automatically release it on completion. 1217 * Instead, we look at the one page we are interested in which we 1218 * still hold a lock on even through the I/O completion. 1219 * 1220 * The other pages in our m[] array are also released on completion, 1221 * so we cannot assume they are valid anymore either. 1222 * 1223 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1224 */ 1225 BUF_KERNPROC(bp); 1226 swp_pager_strategy(bp); 1227 1228 /* 1229 * wait for the page we want to complete. VPO_SWAPINPROG is always 1230 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1231 * is set in the meta-data. 1232 */ 1233 VM_OBJECT_WLOCK(object); 1234 while ((mreq->oflags & VPO_SWAPINPROG) != 0) { 1235 mreq->oflags |= VPO_SWAPSLEEP; 1236 PCPU_INC(cnt.v_intrans); 1237 if (VM_OBJECT_SLEEP(object, &object->paging_in_progress, PSWP, 1238 "swread", hz * 20)) { 1239 printf( 1240"swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1241 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1242 } 1243 } 1244 1245 /* 1246 * mreq is left busied after completion, but all the other pages 1247 * are freed. If we had an unrecoverable read error the page will 1248 * not be valid. 1249 */ 1250 if (mreq->valid != VM_PAGE_BITS_ALL) { 1251 return (VM_PAGER_ERROR); 1252 } else { 1253 return (VM_PAGER_OK); 1254 } 1255 1256 /* 1257 * A final note: in a low swap situation, we cannot deallocate swap 1258 * and mark a page dirty here because the caller is likely to mark 1259 * the page clean when we return, causing the page to possibly revert 1260 * to all-zero's later. 1261 */ 1262} 1263 1264/* 1265 * swap_pager_putpages: 1266 * 1267 * Assign swap (if necessary) and initiate I/O on the specified pages. 1268 * 1269 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1270 * are automatically converted to SWAP objects. 1271 * 1272 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1273 * vm_page reservation system coupled with properly written VFS devices 1274 * should ensure that no low-memory deadlock occurs. This is an area 1275 * which needs work. 1276 * 1277 * The parent has N vm_object_pip_add() references prior to 1278 * calling us and will remove references for rtvals[] that are 1279 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1280 * completion. 1281 * 1282 * The parent has soft-busy'd the pages it passes us and will unbusy 1283 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1284 * We need to unbusy the rest on I/O completion. 1285 */ 1286void 1287swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1288 int flags, int *rtvals) 1289{ 1290 int i, n; 1291 boolean_t sync; 1292 1293 if (count && m[0]->object != object) { 1294 panic("swap_pager_putpages: object mismatch %p/%p", 1295 object, 1296 m[0]->object 1297 ); 1298 } 1299 1300 /* 1301 * Step 1 1302 * 1303 * Turn object into OBJT_SWAP 1304 * check for bogus sysops 1305 * force sync if not pageout process 1306 */ 1307 if (object->type != OBJT_SWAP) 1308 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1309 VM_OBJECT_WUNLOCK(object); 1310 1311 n = 0; 1312 if (curproc != pageproc) 1313 sync = TRUE; 1314 else 1315 sync = (flags & VM_PAGER_PUT_SYNC) != 0; 1316 1317 /* 1318 * Step 2 1319 * 1320 * Update nsw parameters from swap_async_max sysctl values. 1321 * Do not let the sysop crash the machine with bogus numbers. 1322 */ 1323 mtx_lock(&pbuf_mtx); 1324 if (swap_async_max != nsw_wcount_async_max) { 1325 int n; 1326 1327 /* 1328 * limit range 1329 */ 1330 if ((n = swap_async_max) > nswbuf / 2) 1331 n = nswbuf / 2; 1332 if (n < 1) 1333 n = 1; 1334 swap_async_max = n; 1335 1336 /* 1337 * Adjust difference ( if possible ). If the current async 1338 * count is too low, we may not be able to make the adjustment 1339 * at this time. 1340 */ 1341 n -= nsw_wcount_async_max; 1342 if (nsw_wcount_async + n >= 0) { 1343 nsw_wcount_async += n; 1344 nsw_wcount_async_max += n; 1345 wakeup(&nsw_wcount_async); 1346 } 1347 } 1348 mtx_unlock(&pbuf_mtx); 1349 1350 /* 1351 * Step 3 1352 * 1353 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1354 * The page is left dirty until the pageout operation completes 1355 * successfully. 1356 */ 1357 for (i = 0; i < count; i += n) { 1358 int j; 1359 struct buf *bp; 1360 daddr_t blk; 1361 1362 /* 1363 * Maximum I/O size is limited by a number of factors. 1364 */ 1365 n = min(BLIST_MAX_ALLOC, count - i); 1366 n = min(n, nsw_cluster_max); 1367 1368 /* 1369 * Get biggest block of swap we can. If we fail, fall 1370 * back and try to allocate a smaller block. Don't go 1371 * overboard trying to allocate space if it would overly 1372 * fragment swap. 1373 */ 1374 while ( 1375 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE && 1376 n > 4 1377 ) { 1378 n >>= 1; 1379 } 1380 if (blk == SWAPBLK_NONE) { 1381 for (j = 0; j < n; ++j) 1382 rtvals[i+j] = VM_PAGER_FAIL; 1383 continue; 1384 } 1385 1386 /* 1387 * All I/O parameters have been satisfied, build the I/O 1388 * request and assign the swap space. 1389 */ 1390 if (sync == TRUE) { 1391 bp = getpbuf(&nsw_wcount_sync); 1392 } else { 1393 bp = getpbuf(&nsw_wcount_async); 1394 bp->b_flags = B_ASYNC; 1395 } 1396 bp->b_flags |= B_PAGING; 1397 bp->b_iocmd = BIO_WRITE; 1398 1399 bp->b_rcred = crhold(thread0.td_ucred); 1400 bp->b_wcred = crhold(thread0.td_ucred); 1401 bp->b_bcount = PAGE_SIZE * n; 1402 bp->b_bufsize = PAGE_SIZE * n; 1403 bp->b_blkno = blk; 1404 1405 VM_OBJECT_WLOCK(object); 1406 for (j = 0; j < n; ++j) { 1407 vm_page_t mreq = m[i+j]; 1408 1409 swp_pager_meta_build( 1410 mreq->object, 1411 mreq->pindex, 1412 blk + j 1413 ); 1414 vm_page_dirty(mreq); 1415 rtvals[i+j] = VM_PAGER_OK; 1416 1417 mreq->oflags |= VPO_SWAPINPROG; 1418 bp->b_pages[j] = mreq; 1419 } 1420 VM_OBJECT_WUNLOCK(object); 1421 bp->b_npages = n; 1422 /* 1423 * Must set dirty range for NFS to work. 1424 */ 1425 bp->b_dirtyoff = 0; 1426 bp->b_dirtyend = bp->b_bcount; 1427 1428 PCPU_INC(cnt.v_swapout); 1429 PCPU_ADD(cnt.v_swappgsout, bp->b_npages); 1430 1431 /* 1432 * asynchronous 1433 * 1434 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1435 */ 1436 if (sync == FALSE) { 1437 bp->b_iodone = swp_pager_async_iodone; 1438 BUF_KERNPROC(bp); 1439 swp_pager_strategy(bp); 1440 1441 for (j = 0; j < n; ++j) 1442 rtvals[i+j] = VM_PAGER_PEND; 1443 /* restart outter loop */ 1444 continue; 1445 } 1446 1447 /* 1448 * synchronous 1449 * 1450 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1451 */ 1452 bp->b_iodone = bdone; 1453 swp_pager_strategy(bp); 1454 1455 /* 1456 * Wait for the sync I/O to complete, then update rtvals. 1457 * We just set the rtvals[] to VM_PAGER_PEND so we can call 1458 * our async completion routine at the end, thus avoiding a 1459 * double-free. 1460 */ 1461 bwait(bp, PVM, "swwrt"); 1462 for (j = 0; j < n; ++j) 1463 rtvals[i+j] = VM_PAGER_PEND; 1464 /* 1465 * Now that we are through with the bp, we can call the 1466 * normal async completion, which frees everything up. 1467 */ 1468 swp_pager_async_iodone(bp); 1469 } 1470 VM_OBJECT_WLOCK(object); 1471} 1472 1473/* 1474 * swp_pager_async_iodone: 1475 * 1476 * Completion routine for asynchronous reads and writes from/to swap. 1477 * Also called manually by synchronous code to finish up a bp. 1478 * 1479 * This routine may not sleep. 1480 */ 1481static void 1482swp_pager_async_iodone(struct buf *bp) 1483{ 1484 int i; 1485 vm_object_t object = NULL; 1486 1487 /* 1488 * report error 1489 */ 1490 if (bp->b_ioflags & BIO_ERROR) { 1491 printf( 1492 "swap_pager: I/O error - %s failed; blkno %ld," 1493 "size %ld, error %d\n", 1494 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1495 (long)bp->b_blkno, 1496 (long)bp->b_bcount, 1497 bp->b_error 1498 ); 1499 } 1500 1501 /* 1502 * remove the mapping for kernel virtual 1503 */ 1504 if ((bp->b_flags & B_UNMAPPED) != 0) { 1505 bp->b_data = bp->b_kvaalloc; 1506 bp->b_kvabase = bp->b_kvaalloc; 1507 bp->b_flags &= ~B_UNMAPPED; 1508 } else 1509 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1510 1511 if (bp->b_npages) { 1512 object = bp->b_pages[0]->object; 1513 VM_OBJECT_WLOCK(object); 1514 } 1515 1516 /* 1517 * cleanup pages. If an error occurs writing to swap, we are in 1518 * very serious trouble. If it happens to be a disk error, though, 1519 * we may be able to recover by reassigning the swap later on. So 1520 * in this case we remove the m->swapblk assignment for the page 1521 * but do not free it in the rlist. The errornous block(s) are thus 1522 * never reallocated as swap. Redirty the page and continue. 1523 */ 1524 for (i = 0; i < bp->b_npages; ++i) { 1525 vm_page_t m = bp->b_pages[i]; 1526 1527 m->oflags &= ~VPO_SWAPINPROG; 1528 if (m->oflags & VPO_SWAPSLEEP) { 1529 m->oflags &= ~VPO_SWAPSLEEP; 1530 wakeup(&object->paging_in_progress); 1531 } 1532 1533 if (bp->b_ioflags & BIO_ERROR) { 1534 /* 1535 * If an error occurs I'd love to throw the swapblk 1536 * away without freeing it back to swapspace, so it 1537 * can never be used again. But I can't from an 1538 * interrupt. 1539 */ 1540 if (bp->b_iocmd == BIO_READ) { 1541 /* 1542 * When reading, reqpage needs to stay 1543 * locked for the parent, but all other 1544 * pages can be freed. We still want to 1545 * wakeup the parent waiting on the page, 1546 * though. ( also: pg_reqpage can be -1 and 1547 * not match anything ). 1548 * 1549 * We have to wake specifically requested pages 1550 * up too because we cleared VPO_SWAPINPROG and 1551 * someone may be waiting for that. 1552 * 1553 * NOTE: for reads, m->dirty will probably 1554 * be overridden by the original caller of 1555 * getpages so don't play cute tricks here. 1556 */ 1557 m->valid = 0; 1558 if (i != bp->b_pager.pg_reqpage) 1559 swp_pager_free_nrpage(m); 1560 else { 1561 vm_page_lock(m); 1562 vm_page_flash(m); 1563 vm_page_unlock(m); 1564 } 1565 /* 1566 * If i == bp->b_pager.pg_reqpage, do not wake 1567 * the page up. The caller needs to. 1568 */ 1569 } else { 1570 /* 1571 * If a write error occurs, reactivate page 1572 * so it doesn't clog the inactive list, 1573 * then finish the I/O. 1574 */ 1575 vm_page_dirty(m); 1576 vm_page_lock(m); 1577 vm_page_activate(m); 1578 vm_page_unlock(m); 1579 vm_page_sunbusy(m); 1580 } 1581 } else if (bp->b_iocmd == BIO_READ) { 1582 /* 1583 * NOTE: for reads, m->dirty will probably be 1584 * overridden by the original caller of getpages so 1585 * we cannot set them in order to free the underlying 1586 * swap in a low-swap situation. I don't think we'd 1587 * want to do that anyway, but it was an optimization 1588 * that existed in the old swapper for a time before 1589 * it got ripped out due to precisely this problem. 1590 * 1591 * If not the requested page then deactivate it. 1592 * 1593 * Note that the requested page, reqpage, is left 1594 * busied, but we still have to wake it up. The 1595 * other pages are released (unbusied) by 1596 * vm_page_xunbusy(). 1597 */ 1598 KASSERT(!pmap_page_is_mapped(m), 1599 ("swp_pager_async_iodone: page %p is mapped", m)); 1600 m->valid = VM_PAGE_BITS_ALL; 1601 KASSERT(m->dirty == 0, 1602 ("swp_pager_async_iodone: page %p is dirty", m)); 1603 1604 /* 1605 * We have to wake specifically requested pages 1606 * up too because we cleared VPO_SWAPINPROG and 1607 * could be waiting for it in getpages. However, 1608 * be sure to not unbusy getpages specifically 1609 * requested page - getpages expects it to be 1610 * left busy. 1611 */ 1612 if (i != bp->b_pager.pg_reqpage) { 1613 vm_page_lock(m); 1614 vm_page_deactivate(m); 1615 vm_page_unlock(m); 1616 vm_page_xunbusy(m); 1617 } else { 1618 vm_page_lock(m); 1619 vm_page_flash(m); 1620 vm_page_unlock(m); 1621 } 1622 } else { 1623 /* 1624 * For write success, clear the dirty 1625 * status, then finish the I/O ( which decrements the 1626 * busy count and possibly wakes waiter's up ). 1627 */ 1628 KASSERT(!pmap_page_is_write_mapped(m), 1629 ("swp_pager_async_iodone: page %p is not write" 1630 " protected", m)); 1631 vm_page_undirty(m); 1632 vm_page_sunbusy(m); 1633 if (vm_page_count_severe()) { 1634 vm_page_lock(m); 1635 vm_page_try_to_cache(m); 1636 vm_page_unlock(m); 1637 } 1638 } 1639 } 1640 1641 /* 1642 * adjust pip. NOTE: the original parent may still have its own 1643 * pip refs on the object. 1644 */ 1645 if (object != NULL) { 1646 vm_object_pip_wakeupn(object, bp->b_npages); 1647 VM_OBJECT_WUNLOCK(object); 1648 } 1649 1650 /* 1651 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1652 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1653 * trigger a KASSERT in relpbuf(). 1654 */ 1655 if (bp->b_vp) { 1656 bp->b_vp = NULL; 1657 bp->b_bufobj = NULL; 1658 } 1659 /* 1660 * release the physical I/O buffer 1661 */ 1662 relpbuf( 1663 bp, 1664 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount : 1665 ((bp->b_flags & B_ASYNC) ? 1666 &nsw_wcount_async : 1667 &nsw_wcount_sync 1668 ) 1669 ) 1670 ); 1671} 1672 1673/* 1674 * swap_pager_isswapped: 1675 * 1676 * Return 1 if at least one page in the given object is paged 1677 * out to the given swap device. 1678 * 1679 * This routine may not sleep. 1680 */ 1681int 1682swap_pager_isswapped(vm_object_t object, struct swdevt *sp) 1683{ 1684 daddr_t index = 0; 1685 int bcount; 1686 int i; 1687 1688 VM_OBJECT_ASSERT_WLOCKED(object); 1689 if (object->type != OBJT_SWAP) 1690 return (0); 1691 1692 mtx_lock(&swhash_mtx); 1693 for (bcount = 0; bcount < object->un_pager.swp.swp_bcount; bcount++) { 1694 struct swblock *swap; 1695 1696 if ((swap = *swp_pager_hash(object, index)) != NULL) { 1697 for (i = 0; i < SWAP_META_PAGES; ++i) { 1698 if (swp_pager_isondev(swap->swb_pages[i], sp)) { 1699 mtx_unlock(&swhash_mtx); 1700 return (1); 1701 } 1702 } 1703 } 1704 index += SWAP_META_PAGES; 1705 } 1706 mtx_unlock(&swhash_mtx); 1707 return (0); 1708} 1709 1710/* 1711 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in 1712 * 1713 * This routine dissociates the page at the given index within a 1714 * swap block from its backing store, paging it in if necessary. 1715 * If the page is paged in, it is placed in the inactive queue, 1716 * since it had its backing store ripped out from under it. 1717 * We also attempt to swap in all other pages in the swap block, 1718 * we only guarantee that the one at the specified index is 1719 * paged in. 1720 * 1721 * XXX - The code to page the whole block in doesn't work, so we 1722 * revert to the one-by-one behavior for now. Sigh. 1723 */ 1724static inline void 1725swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex) 1726{ 1727 vm_page_t m; 1728 1729 vm_object_pip_add(object, 1); 1730 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL); 1731 if (m->valid == VM_PAGE_BITS_ALL) { 1732 vm_object_pip_subtract(object, 1); 1733 vm_page_dirty(m); 1734 vm_page_lock(m); 1735 vm_page_activate(m); 1736 vm_page_unlock(m); 1737 vm_page_xunbusy(m); 1738 vm_pager_page_unswapped(m); 1739 return; 1740 } 1741 1742 if (swap_pager_getpages(object, &m, 1, 0) != VM_PAGER_OK) 1743 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/ 1744 vm_object_pip_subtract(object, 1); 1745 vm_page_dirty(m); 1746 vm_page_lock(m); 1747 vm_page_deactivate(m); 1748 vm_page_unlock(m); 1749 vm_page_xunbusy(m); 1750 vm_pager_page_unswapped(m); 1751} 1752 1753/* 1754 * swap_pager_swapoff: 1755 * 1756 * Page in all of the pages that have been paged out to the 1757 * given device. The corresponding blocks in the bitmap must be 1758 * marked as allocated and the device must be flagged SW_CLOSING. 1759 * There may be no processes swapped out to the device. 1760 * 1761 * This routine may block. 1762 */ 1763static void 1764swap_pager_swapoff(struct swdevt *sp) 1765{ 1766 struct swblock *swap; 1767 vm_object_t locked_obj, object; 1768 vm_pindex_t pindex; 1769 int i, j, retries; 1770 1771 GIANT_REQUIRED; 1772 1773 retries = 0; 1774 locked_obj = NULL; 1775full_rescan: 1776 mtx_lock(&swhash_mtx); 1777 for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */ 1778restart: 1779 for (swap = swhash[i]; swap != NULL; swap = swap->swb_hnext) { 1780 object = swap->swb_object; 1781 pindex = swap->swb_index; 1782 for (j = 0; j < SWAP_META_PAGES; ++j) { 1783 if (!swp_pager_isondev(swap->swb_pages[j], sp)) 1784 continue; 1785 if (locked_obj != object) { 1786 if (locked_obj != NULL) 1787 VM_OBJECT_WUNLOCK(locked_obj); 1788 locked_obj = object; 1789 if (!VM_OBJECT_TRYWLOCK(object)) { 1790 mtx_unlock(&swhash_mtx); 1791 /* Depends on type-stability. */ 1792 VM_OBJECT_WLOCK(object); 1793 mtx_lock(&swhash_mtx); 1794 goto restart; 1795 } 1796 } 1797 MPASS(locked_obj == object); 1798 mtx_unlock(&swhash_mtx); 1799 swp_pager_force_pagein(object, pindex + j); 1800 mtx_lock(&swhash_mtx); 1801 goto restart; 1802 } 1803 } 1804 } 1805 mtx_unlock(&swhash_mtx); 1806 if (locked_obj != NULL) { 1807 VM_OBJECT_WUNLOCK(locked_obj); 1808 locked_obj = NULL; 1809 } 1810 if (sp->sw_used) { 1811 /* 1812 * Objects may be locked or paging to the device being 1813 * removed, so we will miss their pages and need to 1814 * make another pass. We have marked this device as 1815 * SW_CLOSING, so the activity should finish soon. 1816 */ 1817 retries++; 1818 if (retries > 100) { 1819 panic("swapoff: failed to locate %d swap blocks", 1820 sp->sw_used); 1821 } 1822 pause("swpoff", hz / 20); 1823 goto full_rescan; 1824 } 1825} 1826 1827/************************************************************************ 1828 * SWAP META DATA * 1829 ************************************************************************ 1830 * 1831 * These routines manipulate the swap metadata stored in the 1832 * OBJT_SWAP object. 1833 * 1834 * Swap metadata is implemented with a global hash and not directly 1835 * linked into the object. Instead the object simply contains 1836 * appropriate tracking counters. 1837 */ 1838 1839/* 1840 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1841 * 1842 * We first convert the object to a swap object if it is a default 1843 * object. 1844 * 1845 * The specified swapblk is added to the object's swap metadata. If 1846 * the swapblk is not valid, it is freed instead. Any previously 1847 * assigned swapblk is freed. 1848 */ 1849static void 1850swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1851{ 1852 static volatile int exhausted; 1853 struct swblock *swap; 1854 struct swblock **pswap; 1855 int idx; 1856 1857 VM_OBJECT_ASSERT_WLOCKED(object); 1858 /* 1859 * Convert default object to swap object if necessary 1860 */ 1861 if (object->type != OBJT_SWAP) { 1862 object->type = OBJT_SWAP; 1863 object->un_pager.swp.swp_bcount = 0; 1864 1865 if (object->handle != NULL) { 1866 mtx_lock(&sw_alloc_mtx); 1867 TAILQ_INSERT_TAIL( 1868 NOBJLIST(object->handle), 1869 object, 1870 pager_object_list 1871 ); 1872 mtx_unlock(&sw_alloc_mtx); 1873 } 1874 } 1875 1876 /* 1877 * Locate hash entry. If not found create, but if we aren't adding 1878 * anything just return. If we run out of space in the map we wait 1879 * and, since the hash table may have changed, retry. 1880 */ 1881retry: 1882 mtx_lock(&swhash_mtx); 1883 pswap = swp_pager_hash(object, pindex); 1884 1885 if ((swap = *pswap) == NULL) { 1886 int i; 1887 1888 if (swapblk == SWAPBLK_NONE) 1889 goto done; 1890 1891 swap = *pswap = uma_zalloc(swap_zone, M_NOWAIT | 1892 (curproc == pageproc ? M_USE_RESERVE : 0)); 1893 if (swap == NULL) { 1894 mtx_unlock(&swhash_mtx); 1895 VM_OBJECT_WUNLOCK(object); 1896 if (uma_zone_exhausted(swap_zone)) { 1897 if (atomic_cmpset_int(&exhausted, 0, 1)) 1898 printf("swap zone exhausted, " 1899 "increase kern.maxswzone\n"); 1900 vm_pageout_oom(VM_OOM_SWAPZ); 1901 pause("swzonex", 10); 1902 } else 1903 VM_WAIT; 1904 VM_OBJECT_WLOCK(object); 1905 goto retry; 1906 } 1907 1908 if (atomic_cmpset_int(&exhausted, 1, 0)) 1909 printf("swap zone ok\n"); 1910 1911 swap->swb_hnext = NULL; 1912 swap->swb_object = object; 1913 swap->swb_index = pindex & ~(vm_pindex_t)SWAP_META_MASK; 1914 swap->swb_count = 0; 1915 1916 ++object->un_pager.swp.swp_bcount; 1917 1918 for (i = 0; i < SWAP_META_PAGES; ++i) 1919 swap->swb_pages[i] = SWAPBLK_NONE; 1920 } 1921 1922 /* 1923 * Delete prior contents of metadata 1924 */ 1925 idx = pindex & SWAP_META_MASK; 1926 1927 if (swap->swb_pages[idx] != SWAPBLK_NONE) { 1928 swp_pager_freeswapspace(swap->swb_pages[idx], 1); 1929 --swap->swb_count; 1930 } 1931 1932 /* 1933 * Enter block into metadata 1934 */ 1935 swap->swb_pages[idx] = swapblk; 1936 if (swapblk != SWAPBLK_NONE) 1937 ++swap->swb_count; 1938done: 1939 mtx_unlock(&swhash_mtx); 1940} 1941 1942/* 1943 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 1944 * 1945 * The requested range of blocks is freed, with any associated swap 1946 * returned to the swap bitmap. 1947 * 1948 * This routine will free swap metadata structures as they are cleaned 1949 * out. This routine does *NOT* operate on swap metadata associated 1950 * with resident pages. 1951 */ 1952static void 1953swp_pager_meta_free(vm_object_t object, vm_pindex_t index, daddr_t count) 1954{ 1955 1956 VM_OBJECT_ASSERT_LOCKED(object); 1957 if (object->type != OBJT_SWAP) 1958 return; 1959 1960 while (count > 0) { 1961 struct swblock **pswap; 1962 struct swblock *swap; 1963 1964 mtx_lock(&swhash_mtx); 1965 pswap = swp_pager_hash(object, index); 1966 1967 if ((swap = *pswap) != NULL) { 1968 daddr_t v = swap->swb_pages[index & SWAP_META_MASK]; 1969 1970 if (v != SWAPBLK_NONE) { 1971 swp_pager_freeswapspace(v, 1); 1972 swap->swb_pages[index & SWAP_META_MASK] = 1973 SWAPBLK_NONE; 1974 if (--swap->swb_count == 0) { 1975 *pswap = swap->swb_hnext; 1976 uma_zfree(swap_zone, swap); 1977 --object->un_pager.swp.swp_bcount; 1978 } 1979 } 1980 --count; 1981 ++index; 1982 } else { 1983 int n = SWAP_META_PAGES - (index & SWAP_META_MASK); 1984 count -= n; 1985 index += n; 1986 } 1987 mtx_unlock(&swhash_mtx); 1988 } 1989} 1990 1991/* 1992 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 1993 * 1994 * This routine locates and destroys all swap metadata associated with 1995 * an object. 1996 */ 1997static void 1998swp_pager_meta_free_all(vm_object_t object) 1999{ 2000 daddr_t index = 0; 2001 2002 VM_OBJECT_ASSERT_WLOCKED(object); 2003 if (object->type != OBJT_SWAP) 2004 return; 2005 2006 while (object->un_pager.swp.swp_bcount) { 2007 struct swblock **pswap; 2008 struct swblock *swap; 2009 2010 mtx_lock(&swhash_mtx); 2011 pswap = swp_pager_hash(object, index); 2012 if ((swap = *pswap) != NULL) { 2013 int i; 2014 2015 for (i = 0; i < SWAP_META_PAGES; ++i) { 2016 daddr_t v = swap->swb_pages[i]; 2017 if (v != SWAPBLK_NONE) { 2018 --swap->swb_count; 2019 swp_pager_freeswapspace(v, 1); 2020 } 2021 } 2022 if (swap->swb_count != 0) 2023 panic("swap_pager_meta_free_all: swb_count != 0"); 2024 *pswap = swap->swb_hnext; 2025 uma_zfree(swap_zone, swap); 2026 --object->un_pager.swp.swp_bcount; 2027 } 2028 mtx_unlock(&swhash_mtx); 2029 index += SWAP_META_PAGES; 2030 } 2031} 2032 2033/* 2034 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. 2035 * 2036 * This routine is capable of looking up, popping, or freeing 2037 * swapblk assignments in the swap meta data or in the vm_page_t. 2038 * The routine typically returns the swapblk being looked-up, or popped, 2039 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block 2040 * was invalid. This routine will automatically free any invalid 2041 * meta-data swapblks. 2042 * 2043 * It is not possible to store invalid swapblks in the swap meta data 2044 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking. 2045 * 2046 * When acting on a busy resident page and paging is in progress, we 2047 * have to wait until paging is complete but otherwise can act on the 2048 * busy page. 2049 * 2050 * SWM_FREE remove and free swap block from metadata 2051 * SWM_POP remove from meta data but do not free.. pop it out 2052 */ 2053static daddr_t 2054swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags) 2055{ 2056 struct swblock **pswap; 2057 struct swblock *swap; 2058 daddr_t r1; 2059 int idx; 2060 2061 VM_OBJECT_ASSERT_LOCKED(object); 2062 /* 2063 * The meta data only exists of the object is OBJT_SWAP 2064 * and even then might not be allocated yet. 2065 */ 2066 if (object->type != OBJT_SWAP) 2067 return (SWAPBLK_NONE); 2068 2069 r1 = SWAPBLK_NONE; 2070 mtx_lock(&swhash_mtx); 2071 pswap = swp_pager_hash(object, pindex); 2072 2073 if ((swap = *pswap) != NULL) { 2074 idx = pindex & SWAP_META_MASK; 2075 r1 = swap->swb_pages[idx]; 2076 2077 if (r1 != SWAPBLK_NONE) { 2078 if (flags & SWM_FREE) { 2079 swp_pager_freeswapspace(r1, 1); 2080 r1 = SWAPBLK_NONE; 2081 } 2082 if (flags & (SWM_FREE|SWM_POP)) { 2083 swap->swb_pages[idx] = SWAPBLK_NONE; 2084 if (--swap->swb_count == 0) { 2085 *pswap = swap->swb_hnext; 2086 uma_zfree(swap_zone, swap); 2087 --object->un_pager.swp.swp_bcount; 2088 } 2089 } 2090 } 2091 } 2092 mtx_unlock(&swhash_mtx); 2093 return (r1); 2094} 2095 2096/* 2097 * System call swapon(name) enables swapping on device name, 2098 * which must be in the swdevsw. Return EBUSY 2099 * if already swapping on this device. 2100 */ 2101#ifndef _SYS_SYSPROTO_H_ 2102struct swapon_args { 2103 char *name; 2104}; 2105#endif 2106 2107/* 2108 * MPSAFE 2109 */ 2110/* ARGSUSED */ 2111int 2112sys_swapon(struct thread *td, struct swapon_args *uap) 2113{ 2114 struct vattr attr; 2115 struct vnode *vp; 2116 struct nameidata nd; 2117 int error; 2118 2119 error = priv_check(td, PRIV_SWAPON); 2120 if (error) 2121 return (error); 2122 2123 mtx_lock(&Giant); 2124 while (swdev_syscall_active) 2125 tsleep(&swdev_syscall_active, PUSER - 1, "swpon", 0); 2126 swdev_syscall_active = 1; 2127 2128 /* 2129 * Swap metadata may not fit in the KVM if we have physical 2130 * memory of >1GB. 2131 */ 2132 if (swap_zone == NULL) { 2133 error = ENOMEM; 2134 goto done; 2135 } 2136 2137 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2138 uap->name, td); 2139 error = namei(&nd); 2140 if (error) 2141 goto done; 2142 2143 NDFREE(&nd, NDF_ONLY_PNBUF); 2144 vp = nd.ni_vp; 2145 2146 if (vn_isdisk(vp, &error)) { 2147 error = swapongeom(td, vp); 2148 } else if (vp->v_type == VREG && 2149 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2150 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2151 /* 2152 * Allow direct swapping to NFS regular files in the same 2153 * way that nfs_mountroot() sets up diskless swapping. 2154 */ 2155 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2156 } 2157 2158 if (error) 2159 vrele(vp); 2160done: 2161 swdev_syscall_active = 0; 2162 wakeup_one(&swdev_syscall_active); 2163 mtx_unlock(&Giant); 2164 return (error); 2165} 2166 2167/* 2168 * Check that the total amount of swap currently configured does not 2169 * exceed half the theoretical maximum. If it does, print a warning 2170 * message and return -1; otherwise, return 0. 2171 */ 2172static int 2173swapon_check_swzone(unsigned long npages) 2174{ 2175 unsigned long maxpages; 2176 2177 /* absolute maximum we can handle assuming 100% efficiency */ 2178 maxpages = uma_zone_get_max(swap_zone) * SWAP_META_PAGES; 2179 2180 /* recommend using no more than half that amount */ 2181 if (npages > maxpages / 2) { 2182 printf("warning: total configured swap (%lu pages) " 2183 "exceeds maximum recommended amount (%lu pages).\n", 2184 npages, maxpages / 2); 2185 printf("warning: increase kern.maxswzone " 2186 "or reduce amount of swap.\n"); 2187 return (-1); 2188 } 2189 return (0); 2190} 2191 2192static void 2193swaponsomething(struct vnode *vp, void *id, u_long nblks, 2194 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2195{ 2196 struct swdevt *sp, *tsp; 2197 swblk_t dvbase; 2198 u_long mblocks; 2199 2200 /* 2201 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2202 * First chop nblks off to page-align it, then convert. 2203 * 2204 * sw->sw_nblks is in page-sized chunks now too. 2205 */ 2206 nblks &= ~(ctodb(1) - 1); 2207 nblks = dbtoc(nblks); 2208 2209 /* 2210 * If we go beyond this, we get overflows in the radix 2211 * tree bitmap code. 2212 */ 2213 mblocks = 0x40000000 / BLIST_META_RADIX; 2214 if (nblks > mblocks) { 2215 printf( 2216 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2217 mblocks / 1024 / 1024 * PAGE_SIZE); 2218 nblks = mblocks; 2219 } 2220 2221 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2222 sp->sw_vp = vp; 2223 sp->sw_id = id; 2224 sp->sw_dev = dev; 2225 sp->sw_flags = 0; 2226 sp->sw_nblks = nblks; 2227 sp->sw_used = 0; 2228 sp->sw_strategy = strategy; 2229 sp->sw_close = close; 2230 sp->sw_flags = flags; 2231 2232 sp->sw_blist = blist_create(nblks, M_WAITOK); 2233 /* 2234 * Do not free the first two block in order to avoid overwriting 2235 * any bsd label at the front of the partition 2236 */ 2237 blist_free(sp->sw_blist, 2, nblks - 2); 2238 2239 dvbase = 0; 2240 mtx_lock(&sw_dev_mtx); 2241 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2242 if (tsp->sw_end >= dvbase) { 2243 /* 2244 * We put one uncovered page between the devices 2245 * in order to definitively prevent any cross-device 2246 * I/O requests 2247 */ 2248 dvbase = tsp->sw_end + 1; 2249 } 2250 } 2251 sp->sw_first = dvbase; 2252 sp->sw_end = dvbase + nblks; 2253 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2254 nswapdev++; 2255 swap_pager_avail += nblks; 2256 swap_total += (vm_ooffset_t)nblks * PAGE_SIZE; 2257 swapon_check_swzone(swap_total / PAGE_SIZE); 2258 swp_sizecheck(); 2259 mtx_unlock(&sw_dev_mtx); 2260} 2261 2262/* 2263 * SYSCALL: swapoff(devname) 2264 * 2265 * Disable swapping on the given device. 2266 * 2267 * XXX: Badly designed system call: it should use a device index 2268 * rather than filename as specification. We keep sw_vp around 2269 * only to make this work. 2270 */ 2271#ifndef _SYS_SYSPROTO_H_ 2272struct swapoff_args { 2273 char *name; 2274}; 2275#endif 2276 2277/* 2278 * MPSAFE 2279 */ 2280/* ARGSUSED */ 2281int 2282sys_swapoff(struct thread *td, struct swapoff_args *uap) 2283{ 2284 struct vnode *vp; 2285 struct nameidata nd; 2286 struct swdevt *sp; 2287 int error; 2288 2289 error = priv_check(td, PRIV_SWAPOFF); 2290 if (error) 2291 return (error); 2292 2293 mtx_lock(&Giant); 2294 while (swdev_syscall_active) 2295 tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0); 2296 swdev_syscall_active = 1; 2297 2298 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2299 td); 2300 error = namei(&nd); 2301 if (error) 2302 goto done; 2303 NDFREE(&nd, NDF_ONLY_PNBUF); 2304 vp = nd.ni_vp; 2305 2306 mtx_lock(&sw_dev_mtx); 2307 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2308 if (sp->sw_vp == vp) 2309 break; 2310 } 2311 mtx_unlock(&sw_dev_mtx); 2312 if (sp == NULL) { 2313 error = EINVAL; 2314 goto done; 2315 } 2316 error = swapoff_one(sp, td->td_ucred); 2317done: 2318 swdev_syscall_active = 0; 2319 wakeup_one(&swdev_syscall_active); 2320 mtx_unlock(&Giant); 2321 return (error); 2322} 2323 2324static int 2325swapoff_one(struct swdevt *sp, struct ucred *cred) 2326{ 2327 u_long nblks, dvbase; 2328#ifdef MAC 2329 int error; 2330#endif 2331 2332 mtx_assert(&Giant, MA_OWNED); 2333#ifdef MAC 2334 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2335 error = mac_system_check_swapoff(cred, sp->sw_vp); 2336 (void) VOP_UNLOCK(sp->sw_vp, 0); 2337 if (error != 0) 2338 return (error); 2339#endif 2340 nblks = sp->sw_nblks; 2341 2342 /* 2343 * We can turn off this swap device safely only if the 2344 * available virtual memory in the system will fit the amount 2345 * of data we will have to page back in, plus an epsilon so 2346 * the system doesn't become critically low on swap space. 2347 */ 2348 if (cnt.v_free_count + cnt.v_cache_count + swap_pager_avail < 2349 nblks + nswap_lowat) { 2350 return (ENOMEM); 2351 } 2352 2353 /* 2354 * Prevent further allocations on this device. 2355 */ 2356 mtx_lock(&sw_dev_mtx); 2357 sp->sw_flags |= SW_CLOSING; 2358 for (dvbase = 0; dvbase < sp->sw_end; dvbase += dmmax) { 2359 swap_pager_avail -= blist_fill(sp->sw_blist, 2360 dvbase, dmmax); 2361 } 2362 swap_total -= (vm_ooffset_t)nblks * PAGE_SIZE; 2363 mtx_unlock(&sw_dev_mtx); 2364 2365 /* 2366 * Page in the contents of the device and close it. 2367 */ 2368 swap_pager_swapoff(sp); 2369 2370 sp->sw_close(curthread, sp); 2371 mtx_lock(&sw_dev_mtx); 2372 sp->sw_id = NULL; 2373 TAILQ_REMOVE(&swtailq, sp, sw_list); 2374 nswapdev--; 2375 if (nswapdev == 0) { 2376 swap_pager_full = 2; 2377 swap_pager_almost_full = 1; 2378 } 2379 if (swdevhd == sp) 2380 swdevhd = NULL; 2381 mtx_unlock(&sw_dev_mtx); 2382 blist_destroy(sp->sw_blist); 2383 free(sp, M_VMPGDATA); 2384 return (0); 2385} 2386 2387void 2388swapoff_all(void) 2389{ 2390 struct swdevt *sp, *spt; 2391 const char *devname; 2392 int error; 2393 2394 mtx_lock(&Giant); 2395 while (swdev_syscall_active) 2396 tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0); 2397 swdev_syscall_active = 1; 2398 2399 mtx_lock(&sw_dev_mtx); 2400 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2401 mtx_unlock(&sw_dev_mtx); 2402 if (vn_isdisk(sp->sw_vp, NULL)) 2403 devname = devtoname(sp->sw_vp->v_rdev); 2404 else 2405 devname = "[file]"; 2406 error = swapoff_one(sp, thread0.td_ucred); 2407 if (error != 0) { 2408 printf("Cannot remove swap device %s (error=%d), " 2409 "skipping.\n", devname, error); 2410 } else if (bootverbose) { 2411 printf("Swap device %s removed.\n", devname); 2412 } 2413 mtx_lock(&sw_dev_mtx); 2414 } 2415 mtx_unlock(&sw_dev_mtx); 2416 2417 swdev_syscall_active = 0; 2418 wakeup_one(&swdev_syscall_active); 2419 mtx_unlock(&Giant); 2420} 2421 2422void 2423swap_pager_status(int *total, int *used) 2424{ 2425 struct swdevt *sp; 2426 2427 *total = 0; 2428 *used = 0; 2429 mtx_lock(&sw_dev_mtx); 2430 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2431 *total += sp->sw_nblks; 2432 *used += sp->sw_used; 2433 } 2434 mtx_unlock(&sw_dev_mtx); 2435} 2436 2437int 2438swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2439{ 2440 struct swdevt *sp; 2441 const char *tmp_devname; 2442 int error, n; 2443 2444 n = 0; 2445 error = ENOENT; 2446 mtx_lock(&sw_dev_mtx); 2447 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2448 if (n != name) { 2449 n++; 2450 continue; 2451 } 2452 xs->xsw_version = XSWDEV_VERSION; 2453 xs->xsw_dev = sp->sw_dev; 2454 xs->xsw_flags = sp->sw_flags; 2455 xs->xsw_nblks = sp->sw_nblks; 2456 xs->xsw_used = sp->sw_used; 2457 if (devname != NULL) { 2458 if (vn_isdisk(sp->sw_vp, NULL)) 2459 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2460 else 2461 tmp_devname = "[file]"; 2462 strncpy(devname, tmp_devname, len); 2463 } 2464 error = 0; 2465 break; 2466 } 2467 mtx_unlock(&sw_dev_mtx); 2468 return (error); 2469} 2470 2471static int 2472sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2473{ 2474 struct xswdev xs; 2475 int error; 2476 2477 if (arg2 != 1) /* name length */ 2478 return (EINVAL); 2479 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2480 if (error != 0) 2481 return (error); 2482 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2483 return (error); 2484} 2485 2486SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2487 "Number of swap devices"); 2488SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD, sysctl_vm_swap_info, 2489 "Swap statistics by device"); 2490 2491/* 2492 * vmspace_swap_count() - count the approximate swap usage in pages for a 2493 * vmspace. 2494 * 2495 * The map must be locked. 2496 * 2497 * Swap usage is determined by taking the proportional swap used by 2498 * VM objects backing the VM map. To make up for fractional losses, 2499 * if the VM object has any swap use at all the associated map entries 2500 * count for at least 1 swap page. 2501 */ 2502long 2503vmspace_swap_count(struct vmspace *vmspace) 2504{ 2505 vm_map_t map; 2506 vm_map_entry_t cur; 2507 vm_object_t object; 2508 long count, n; 2509 2510 map = &vmspace->vm_map; 2511 count = 0; 2512 2513 for (cur = map->header.next; cur != &map->header; cur = cur->next) { 2514 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 && 2515 (object = cur->object.vm_object) != NULL) { 2516 VM_OBJECT_WLOCK(object); 2517 if (object->type == OBJT_SWAP && 2518 object->un_pager.swp.swp_bcount != 0) { 2519 n = (cur->end - cur->start) / PAGE_SIZE; 2520 count += object->un_pager.swp.swp_bcount * 2521 SWAP_META_PAGES * n / object->size + 1; 2522 } 2523 VM_OBJECT_WUNLOCK(object); 2524 } 2525 } 2526 return (count); 2527} 2528 2529/* 2530 * GEOM backend 2531 * 2532 * Swapping onto disk devices. 2533 * 2534 */ 2535 2536static g_orphan_t swapgeom_orphan; 2537 2538static struct g_class g_swap_class = { 2539 .name = "SWAP", 2540 .version = G_VERSION, 2541 .orphan = swapgeom_orphan, 2542}; 2543 2544DECLARE_GEOM_CLASS(g_swap_class, g_class); 2545 2546 2547static void 2548swapgeom_close_ev(void *arg, int flags) 2549{ 2550 struct g_consumer *cp; 2551 2552 cp = arg; 2553 g_access(cp, -1, -1, 0); 2554 g_detach(cp); 2555 g_destroy_consumer(cp); 2556} 2557 2558/* 2559 * Add a reference to the g_consumer for an inflight transaction. 2560 */ 2561static void 2562swapgeom_acquire(struct g_consumer *cp) 2563{ 2564 2565 mtx_assert(&sw_dev_mtx, MA_OWNED); 2566 cp->index++; 2567} 2568 2569/* 2570 * Remove a reference from the g_consumer. Post a close event if 2571 * all referneces go away. 2572 */ 2573static void 2574swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2575{ 2576 2577 mtx_assert(&sw_dev_mtx, MA_OWNED); 2578 cp->index--; 2579 if (cp->index == 0) { 2580 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2581 sp->sw_id = NULL; 2582 } 2583} 2584 2585static void 2586swapgeom_done(struct bio *bp2) 2587{ 2588 struct swdevt *sp; 2589 struct buf *bp; 2590 struct g_consumer *cp; 2591 2592 bp = bp2->bio_caller2; 2593 cp = bp2->bio_from; 2594 bp->b_ioflags = bp2->bio_flags; 2595 if (bp2->bio_error) 2596 bp->b_ioflags |= BIO_ERROR; 2597 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2598 bp->b_error = bp2->bio_error; 2599 bufdone(bp); 2600 sp = bp2->bio_caller1; 2601 mtx_lock(&sw_dev_mtx); 2602 swapgeom_release(cp, sp); 2603 mtx_unlock(&sw_dev_mtx); 2604 g_destroy_bio(bp2); 2605} 2606 2607static void 2608swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2609{ 2610 struct bio *bio; 2611 struct g_consumer *cp; 2612 2613 mtx_lock(&sw_dev_mtx); 2614 cp = sp->sw_id; 2615 if (cp == NULL) { 2616 mtx_unlock(&sw_dev_mtx); 2617 bp->b_error = ENXIO; 2618 bp->b_ioflags |= BIO_ERROR; 2619 bufdone(bp); 2620 return; 2621 } 2622 swapgeom_acquire(cp); 2623 mtx_unlock(&sw_dev_mtx); 2624 if (bp->b_iocmd == BIO_WRITE) 2625 bio = g_new_bio(); 2626 else 2627 bio = g_alloc_bio(); 2628 if (bio == NULL) { 2629 mtx_lock(&sw_dev_mtx); 2630 swapgeom_release(cp, sp); 2631 mtx_unlock(&sw_dev_mtx); 2632 bp->b_error = ENOMEM; 2633 bp->b_ioflags |= BIO_ERROR; 2634 bufdone(bp); 2635 return; 2636 } 2637 2638 bio->bio_caller1 = sp; 2639 bio->bio_caller2 = bp; 2640 bio->bio_cmd = bp->b_iocmd; 2641 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2642 bio->bio_length = bp->b_bcount; 2643 bio->bio_done = swapgeom_done; 2644 if ((bp->b_flags & B_UNMAPPED) != 0) { 2645 bio->bio_ma = bp->b_pages; 2646 bio->bio_data = unmapped_buf; 2647 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2648 bio->bio_ma_n = bp->b_npages; 2649 bio->bio_flags |= BIO_UNMAPPED; 2650 } else { 2651 bio->bio_data = bp->b_data; 2652 bio->bio_ma = NULL; 2653 } 2654 g_io_request(bio, cp); 2655 return; 2656} 2657 2658static void 2659swapgeom_orphan(struct g_consumer *cp) 2660{ 2661 struct swdevt *sp; 2662 int destroy; 2663 2664 mtx_lock(&sw_dev_mtx); 2665 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2666 if (sp->sw_id == cp) { 2667 sp->sw_flags |= SW_CLOSING; 2668 break; 2669 } 2670 } 2671 /* 2672 * Drop reference we were created with. Do directly since we're in a 2673 * special context where we don't have to queue the call to 2674 * swapgeom_close_ev(). 2675 */ 2676 cp->index--; 2677 destroy = ((sp != NULL) && (cp->index == 0)); 2678 if (destroy) 2679 sp->sw_id = NULL; 2680 mtx_unlock(&sw_dev_mtx); 2681 if (destroy) 2682 swapgeom_close_ev(cp, 0); 2683} 2684 2685static void 2686swapgeom_close(struct thread *td, struct swdevt *sw) 2687{ 2688 struct g_consumer *cp; 2689 2690 mtx_lock(&sw_dev_mtx); 2691 cp = sw->sw_id; 2692 sw->sw_id = NULL; 2693 mtx_unlock(&sw_dev_mtx); 2694 /* XXX: direct call when Giant untangled */ 2695 if (cp != NULL) 2696 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2697} 2698 2699 2700struct swh0h0 { 2701 struct cdev *dev; 2702 struct vnode *vp; 2703 int error; 2704}; 2705 2706static void 2707swapongeom_ev(void *arg, int flags) 2708{ 2709 struct swh0h0 *swh; 2710 struct g_provider *pp; 2711 struct g_consumer *cp; 2712 static struct g_geom *gp; 2713 struct swdevt *sp; 2714 u_long nblks; 2715 int error; 2716 2717 swh = arg; 2718 swh->error = 0; 2719 pp = g_dev_getprovider(swh->dev); 2720 if (pp == NULL) { 2721 swh->error = ENODEV; 2722 return; 2723 } 2724 mtx_lock(&sw_dev_mtx); 2725 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2726 cp = sp->sw_id; 2727 if (cp != NULL && cp->provider == pp) { 2728 mtx_unlock(&sw_dev_mtx); 2729 swh->error = EBUSY; 2730 return; 2731 } 2732 } 2733 mtx_unlock(&sw_dev_mtx); 2734 if (gp == NULL) 2735 gp = g_new_geomf(&g_swap_class, "swap"); 2736 cp = g_new_consumer(gp); 2737 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2738 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2739 g_attach(cp, pp); 2740 /* 2741 * XXX: Everytime you think you can improve the margin for 2742 * footshooting, somebody depends on the ability to do so: 2743 * savecore(8) wants to write to our swapdev so we cannot 2744 * set an exclusive count :-( 2745 */ 2746 error = g_access(cp, 1, 1, 0); 2747 if (error) { 2748 g_detach(cp); 2749 g_destroy_consumer(cp); 2750 swh->error = error; 2751 return; 2752 } 2753 nblks = pp->mediasize / DEV_BSIZE; 2754 swaponsomething(swh->vp, cp, nblks, swapgeom_strategy, 2755 swapgeom_close, dev2udev(swh->dev), 2756 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2757 swh->error = 0; 2758} 2759 2760static int 2761swapongeom(struct thread *td, struct vnode *vp) 2762{ 2763 int error; 2764 struct swh0h0 swh; 2765 2766 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2767 2768 swh.dev = vp->v_rdev; 2769 swh.vp = vp; 2770 swh.error = 0; 2771 /* XXX: direct call when Giant untangled */ 2772 error = g_waitfor_event(swapongeom_ev, &swh, M_WAITOK, NULL); 2773 if (!error) 2774 error = swh.error; 2775 VOP_UNLOCK(vp, 0); 2776 return (error); 2777} 2778 2779/* 2780 * VNODE backend 2781 * 2782 * This is used mainly for network filesystem (read: probably only tested 2783 * with NFS) swapfiles. 2784 * 2785 */ 2786 2787static void 2788swapdev_strategy(struct buf *bp, struct swdevt *sp) 2789{ 2790 struct vnode *vp2; 2791 2792 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2793 2794 vp2 = sp->sw_id; 2795 vhold(vp2); 2796 if (bp->b_iocmd == BIO_WRITE) { 2797 if (bp->b_bufobj) 2798 bufobj_wdrop(bp->b_bufobj); 2799 bufobj_wref(&vp2->v_bufobj); 2800 } 2801 if (bp->b_bufobj != &vp2->v_bufobj) 2802 bp->b_bufobj = &vp2->v_bufobj; 2803 bp->b_vp = vp2; 2804 bp->b_iooffset = dbtob(bp->b_blkno); 2805 bstrategy(bp); 2806 return; 2807} 2808 2809static void 2810swapdev_close(struct thread *td, struct swdevt *sp) 2811{ 2812 2813 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2814 vrele(sp->sw_vp); 2815} 2816 2817 2818static int 2819swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2820{ 2821 struct swdevt *sp; 2822 int error; 2823 2824 if (nblks == 0) 2825 return (ENXIO); 2826 mtx_lock(&sw_dev_mtx); 2827 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2828 if (sp->sw_id == vp) { 2829 mtx_unlock(&sw_dev_mtx); 2830 return (EBUSY); 2831 } 2832 } 2833 mtx_unlock(&sw_dev_mtx); 2834 2835 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2836#ifdef MAC 2837 error = mac_system_check_swapon(td->td_ucred, vp); 2838 if (error == 0) 2839#endif 2840 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 2841 (void) VOP_UNLOCK(vp, 0); 2842 if (error) 2843 return (error); 2844 2845 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 2846 NODEV, 0); 2847 return (0); 2848} 2849