1 /*- 2 * Copyright (c) 1998 Matthew Dillon, 3 * Copyright (c) 1994 John S. Dyson 4 * Copyright (c) 1990 University of Utah. 5 * Copyright (c) 1982, 1986, 1989, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * This code is derived from software contributed to Berkeley by 9 * the Systems Programming Group of the University of Utah Computer 10 * Science Department. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 * 40 * New Swap System 41 * Matthew Dillon 42 * 43 * Radix Bitmap 'blists'. 44 * 45 * - The new swapper uses the new radix bitmap code. This should scale 46 * to arbitrarily small or arbitrarily large swap spaces and an almost 47 * arbitrary degree of fragmentation. 48 * 49 * Features: 50 * 51 * - on the fly reallocation of swap during putpages. The new system 52 * does not try to keep previously allocated swap blocks for dirty 53 * pages. 54 * 55 * - on the fly deallocation of swap 56 * 57 * - No more garbage collection required. Unnecessarily allocated swap 58 * blocks only exist for dirty vm_page_t's now and these are already 59 * cycled (in a high-load system) by the pager. We also do on-the-fly 60 * removal of invalidated swap blocks when a page is destroyed 61 * or renamed. 62 * 63 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$ 64 * 65 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94 66 * @(#)vm_swap.c 8.5 (Berkeley) 2/17/94 67 */ 68 69 #include <sys/cdefs.h> 70 __FBSDID("$FreeBSD$"); 71 72 #include "opt_compat.h" 73 #include "opt_swap.h" 74 #include "opt_vm.h" 75 76 #include <sys/param.h> 77 #include <sys/systm.h> 78 #include <sys/conf.h> 79 #include <sys/kernel.h> 80 #include <sys/priv.h> 81 #include <sys/proc.h> 82 #include <sys/bio.h> 83 #include <sys/buf.h> 84 #include <sys/disk.h> 85 #include <sys/fcntl.h> 86 #include <sys/mount.h> 87 #include <sys/namei.h> 88 #include <sys/vnode.h> 89 #include <sys/malloc.h> 90 #include <sys/racct.h> 91 #include <sys/resource.h> 92 #include <sys/resourcevar.h> 93 #include <sys/rwlock.h> 94 #include <sys/sysctl.h> 95 #include <sys/sysproto.h> 96 #include <sys/blist.h> 97 #include <sys/lock.h> 98 #include <sys/sx.h> 99 #include <sys/vmmeter.h> 100 101 #include <security/mac/mac_framework.h> 102 103 #include <vm/vm.h> 104 #include <vm/pmap.h> 105 #include <vm/vm_map.h> 106 #include <vm/vm_kern.h> 107 #include <vm/vm_object.h> 108 #include <vm/vm_page.h> 109 #include <vm/vm_pager.h> 110 #include <vm/vm_pageout.h> 111 #include <vm/vm_param.h> 112 #include <vm/swap_pager.h> 113 #include <vm/vm_extern.h> 114 #include <vm/uma.h> 115 116 #include <geom/geom.h> 117 118 /* 119 * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64. 120 * The 64-page limit is due to the radix code (kern/subr_blist.c). 121 */ 122 #ifndef MAX_PAGEOUT_CLUSTER 123 #define MAX_PAGEOUT_CLUSTER 32 124 #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 SWAP_META_PAGES 32 138 #define SWAP_META_MASK (SWAP_META_PAGES - 1) 139 140 struct swblock { 141 struct swblock *swb_hnext; 142 vm_object_t swb_object; 143 vm_pindex_t swb_index; 144 int swb_count; 145 daddr_t swb_pages[SWAP_META_PAGES]; 146 }; 147 148 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); 149 static struct mtx sw_dev_mtx; 150 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 151 static struct swdevt *swdevhd; /* Allocate from here next */ 152 static int nswapdev; /* Number of swap devices */ 153 int swap_pager_avail; 154 static struct sx swdev_syscall_lock; /* serialize swap(on|off) */ 155 156 static vm_ooffset_t swap_total; 157 SYSCTL_QUAD(_vm, OID_AUTO, swap_total, CTLFLAG_RD, &swap_total, 0, 158 "Total amount of available swap storage."); 159 static vm_ooffset_t swap_reserved; 160 SYSCTL_QUAD(_vm, OID_AUTO, swap_reserved, CTLFLAG_RD, &swap_reserved, 0, 161 "Amount of swap storage needed to back all allocated anonymous memory."); 162 static int overcommit = 0; 163 SYSCTL_INT(_vm, OID_AUTO, overcommit, CTLFLAG_RW, &overcommit, 0, 164 "Configure virtual memory overcommit behavior. See tuning(7) " 165 "for details."); 166 static unsigned long swzone; 167 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 168 "Actual size of swap metadata zone"); 169 static unsigned long swap_maxpages; 170 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, 171 "Maximum amount of swap supported"); 172 173 /* bits from overcommit */ 174 #define SWAP_RESERVE_FORCE_ON (1 << 0) 175 #define SWAP_RESERVE_RLIMIT_ON (1 << 1) 176 #define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2) 177 178 int 179 swap_reserve(vm_ooffset_t incr) 180 { 181 182 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 183 } 184 185 int 186 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 187 { 188 vm_ooffset_t r, s; 189 int res, error; 190 static int curfail; 191 static struct timeval lastfail; 192 struct uidinfo *uip; 193 194 uip = cred->cr_ruidinfo; 195 196 if (incr & PAGE_MASK) 197 panic("swap_reserve: & PAGE_MASK"); 198 199 #ifdef RACCT 200 if (racct_enable) { 201 PROC_LOCK(curproc); 202 error = racct_add(curproc, RACCT_SWAP, incr); 203 PROC_UNLOCK(curproc); 204 if (error != 0) 205 return (0); 206 } 207 #endif 208 209 res = 0; 210 mtx_lock(&sw_dev_mtx); 211 r = swap_reserved + incr; 212 if (overcommit & SWAP_RESERVE_ALLOW_NONWIRED) { 213 s = vm_cnt.v_page_count - vm_cnt.v_free_reserved - vm_cnt.v_wire_count; 214 s *= PAGE_SIZE; 215 } else 216 s = 0; 217 s += swap_total; 218 if ((overcommit & SWAP_RESERVE_FORCE_ON) == 0 || r <= s || 219 (error = priv_check(curthread, PRIV_VM_SWAP_NOQUOTA)) == 0) { 220 res = 1; 221 swap_reserved = r; 222 } 223 mtx_unlock(&sw_dev_mtx); 224 225 if (res) { 226 UIDINFO_VMSIZE_LOCK(uip); 227 if ((overcommit & SWAP_RESERVE_RLIMIT_ON) != 0 && 228 uip->ui_vmsize + incr > lim_cur(curthread, 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 if (!res) { 235 mtx_lock(&sw_dev_mtx); 236 swap_reserved -= incr; 237 mtx_unlock(&sw_dev_mtx); 238 } 239 } 240 if (!res && ppsratecheck(&lastfail, &curfail, 1)) { 241 printf("uid %d, pid %d: swap reservation for %jd bytes failed\n", 242 uip->ui_uid, curproc->p_pid, incr); 243 } 244 245 #ifdef RACCT 246 if (!res) { 247 PROC_LOCK(curproc); 248 racct_sub(curproc, RACCT_SWAP, incr); 249 PROC_UNLOCK(curproc); 250 } 251 #endif 252 253 return (res); 254 } 255 256 void 257 swap_reserve_force(vm_ooffset_t incr) 258 { 259 struct uidinfo *uip; 260 261 mtx_lock(&sw_dev_mtx); 262 swap_reserved += incr; 263 mtx_unlock(&sw_dev_mtx); 264 265 #ifdef RACCT 266 PROC_LOCK(curproc); 267 racct_add_force(curproc, RACCT_SWAP, incr); 268 PROC_UNLOCK(curproc); 269 #endif 270 271 uip = curthread->td_ucred->cr_ruidinfo; 272 PROC_LOCK(curproc); 273 UIDINFO_VMSIZE_LOCK(uip); 274 uip->ui_vmsize += incr; 275 UIDINFO_VMSIZE_UNLOCK(uip); 276 PROC_UNLOCK(curproc); 277 } 278 279 void 280 swap_release(vm_ooffset_t decr) 281 { 282 struct ucred *cred; 283 284 PROC_LOCK(curproc); 285 cred = curthread->td_ucred; 286 swap_release_by_cred(decr, cred); 287 PROC_UNLOCK(curproc); 288 } 289 290 void 291 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 292 { 293 struct uidinfo *uip; 294 295 uip = cred->cr_ruidinfo; 296 297 if (decr & PAGE_MASK) 298 panic("swap_release: & PAGE_MASK"); 299 300 mtx_lock(&sw_dev_mtx); 301 if (swap_reserved < decr) 302 panic("swap_reserved < decr"); 303 swap_reserved -= decr; 304 mtx_unlock(&sw_dev_mtx); 305 306 UIDINFO_VMSIZE_LOCK(uip); 307 if (uip->ui_vmsize < decr) 308 printf("negative vmsize for uid = %d\n", uip->ui_uid); 309 uip->ui_vmsize -= decr; 310 UIDINFO_VMSIZE_UNLOCK(uip); 311 312 racct_sub_cred(cred, RACCT_SWAP, decr); 313 } 314 315 #define SWM_FREE 0x02 /* free, period */ 316 #define SWM_POP 0x04 /* pop out */ 317 318 int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 319 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 320 static int nsw_rcount; /* free read buffers */ 321 static int nsw_wcount_sync; /* limit write buffers / synchronous */ 322 static int nsw_wcount_async; /* limit write buffers / asynchronous */ 323 static int nsw_wcount_async_max;/* assigned maximum */ 324 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 325 326 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 327 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 328 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 329 "Maximum running async swap ops"); 330 331 static struct swblock **swhash; 332 static int swhash_mask; 333 static struct mtx swhash_mtx; 334 335 static struct sx sw_alloc_sx; 336 337 /* 338 * "named" and "unnamed" anon region objects. Try to reduce the overhead 339 * of searching a named list by hashing it just a little. 340 */ 341 342 #define NOBJLISTS 8 343 344 #define NOBJLIST(handle) \ 345 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 346 347 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 348 static uma_zone_t swap_zone; 349 350 /* 351 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 352 * calls hooked from other parts of the VM system and do not appear here. 353 * (see vm/swap_pager.h). 354 */ 355 static vm_object_t 356 swap_pager_alloc(void *handle, vm_ooffset_t size, 357 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 358 static void swap_pager_dealloc(vm_object_t object); 359 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int *, 360 int *); 361 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int *, 362 int *, pgo_getpages_iodone_t, void *); 363 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 364 static boolean_t 365 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 366 static void swap_pager_init(void); 367 static void swap_pager_unswapped(vm_page_t); 368 static void swap_pager_swapoff(struct swdevt *sp); 369 370 struct pagerops swappagerops = { 371 .pgo_init = swap_pager_init, /* early system initialization of pager */ 372 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 373 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 374 .pgo_getpages = swap_pager_getpages, /* pagein */ 375 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 376 .pgo_putpages = swap_pager_putpages, /* pageout */ 377 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 378 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 379 }; 380 381 /* 382 * swap_*() routines are externally accessible. swp_*() routines are 383 * internal. 384 */ 385 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 386 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 387 388 SYSCTL_INT(_vm, OID_AUTO, dmmax, CTLFLAG_RD, &nsw_cluster_max, 0, 389 "Maximum size of a swap block in pages"); 390 391 static void swp_sizecheck(void); 392 static void swp_pager_async_iodone(struct buf *bp); 393 static int swapongeom(struct vnode *); 394 static int swaponvp(struct thread *, struct vnode *, u_long); 395 static int swapoff_one(struct swdevt *sp, struct ucred *cred); 396 397 /* 398 * Swap bitmap functions 399 */ 400 static void swp_pager_freeswapspace(daddr_t blk, int npages); 401 static daddr_t swp_pager_getswapspace(int npages); 402 403 /* 404 * Metadata functions 405 */ 406 static struct swblock **swp_pager_hash(vm_object_t object, vm_pindex_t index); 407 static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 408 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 409 static void swp_pager_meta_free_all(vm_object_t); 410 static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 411 412 /* 413 * SWP_SIZECHECK() - update swap_pager_full indication 414 * 415 * update the swap_pager_almost_full indication and warn when we are 416 * about to run out of swap space, using lowat/hiwat hysteresis. 417 * 418 * Clear swap_pager_full ( task killing ) indication when lowat is met. 419 * 420 * No restrictions on call 421 * This routine may not block. 422 */ 423 static void 424 swp_sizecheck(void) 425 { 426 427 if (swap_pager_avail < nswap_lowat) { 428 if (swap_pager_almost_full == 0) { 429 printf("swap_pager: out of swap space\n"); 430 swap_pager_almost_full = 1; 431 } 432 } else { 433 swap_pager_full = 0; 434 if (swap_pager_avail > nswap_hiwat) 435 swap_pager_almost_full = 0; 436 } 437 } 438 439 /* 440 * SWP_PAGER_HASH() - hash swap meta data 441 * 442 * This is an helper function which hashes the swapblk given 443 * the object and page index. It returns a pointer to a pointer 444 * to the object, or a pointer to a NULL pointer if it could not 445 * find a swapblk. 446 */ 447 static struct swblock ** 448 swp_pager_hash(vm_object_t object, vm_pindex_t index) 449 { 450 struct swblock **pswap; 451 struct swblock *swap; 452 453 index &= ~(vm_pindex_t)SWAP_META_MASK; 454 pswap = &swhash[(index ^ (int)(intptr_t)object) & swhash_mask]; 455 while ((swap = *pswap) != NULL) { 456 if (swap->swb_object == object && 457 swap->swb_index == index 458 ) { 459 break; 460 } 461 pswap = &swap->swb_hnext; 462 } 463 return (pswap); 464 } 465 466 /* 467 * SWAP_PAGER_INIT() - initialize the swap pager! 468 * 469 * Expected to be started from system init. NOTE: This code is run 470 * before much else so be careful what you depend on. Most of the VM 471 * system has yet to be initialized at this point. 472 */ 473 static void 474 swap_pager_init(void) 475 { 476 /* 477 * Initialize object lists 478 */ 479 int i; 480 481 for (i = 0; i < NOBJLISTS; ++i) 482 TAILQ_INIT(&swap_pager_object_list[i]); 483 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 484 sx_init(&sw_alloc_sx, "swspsx"); 485 sx_init(&swdev_syscall_lock, "swsysc"); 486 } 487 488 /* 489 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 490 * 491 * Expected to be started from pageout process once, prior to entering 492 * its main loop. 493 */ 494 void 495 swap_pager_swap_init(void) 496 { 497 unsigned long n, n2; 498 499 /* 500 * Number of in-transit swap bp operations. Don't 501 * exhaust the pbufs completely. Make sure we 502 * initialize workable values (0 will work for hysteresis 503 * but it isn't very efficient). 504 * 505 * The nsw_cluster_max is constrained by the bp->b_pages[] 506 * array (MAXPHYS/PAGE_SIZE) and our locally defined 507 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 508 * constrained by the swap device interleave stripe size. 509 * 510 * Currently we hardwire nsw_wcount_async to 4. This limit is 511 * designed to prevent other I/O from having high latencies due to 512 * our pageout I/O. The value 4 works well for one or two active swap 513 * devices but is probably a little low if you have more. Even so, 514 * a higher value would probably generate only a limited improvement 515 * with three or four active swap devices since the system does not 516 * typically have to pageout at extreme bandwidths. We will want 517 * at least 2 per swap devices, and 4 is a pretty good value if you 518 * have one NFS swap device due to the command/ack latency over NFS. 519 * So it all works out pretty well. 520 */ 521 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER); 522 523 mtx_lock(&pbuf_mtx); 524 nsw_rcount = (nswbuf + 1) / 2; 525 nsw_wcount_sync = (nswbuf + 3) / 4; 526 nsw_wcount_async = 4; 527 nsw_wcount_async_max = nsw_wcount_async; 528 mtx_unlock(&pbuf_mtx); 529 530 /* 531 * Initialize our zone. Right now I'm just guessing on the number 532 * we need based on the number of pages in the system. Each swblock 533 * can hold 32 pages, so this is probably overkill. This reservation 534 * is typically limited to around 32MB by default. 535 */ 536 n = vm_cnt.v_page_count / 2; 537 if (maxswzone && n > maxswzone / sizeof(struct swblock)) 538 n = maxswzone / sizeof(struct swblock); 539 n2 = n; 540 swap_zone = uma_zcreate("SWAPMETA", sizeof(struct swblock), NULL, NULL, 541 NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE | UMA_ZONE_VM); 542 if (swap_zone == NULL) 543 panic("failed to create swap_zone."); 544 do { 545 if (uma_zone_reserve_kva(swap_zone, n)) 546 break; 547 /* 548 * if the allocation failed, try a zone two thirds the 549 * size of the previous attempt. 550 */ 551 n -= ((n + 2) / 3); 552 } while (n > 0); 553 if (n2 != n) 554 printf("Swap zone entries reduced from %lu to %lu.\n", n2, n); 555 swap_maxpages = n * SWAP_META_PAGES; 556 swzone = n * sizeof(struct swblock); 557 n2 = n; 558 559 /* 560 * Initialize our meta-data hash table. The swapper does not need to 561 * be quite as efficient as the VM system, so we do not use an 562 * oversized hash table. 563 * 564 * n: size of hash table, must be power of 2 565 * swhash_mask: hash table index mask 566 */ 567 for (n = 1; n < n2 / 8; n *= 2) 568 ; 569 swhash = malloc(sizeof(struct swblock *) * n, M_VMPGDATA, M_WAITOK | M_ZERO); 570 swhash_mask = n - 1; 571 mtx_init(&swhash_mtx, "swap_pager swhash", NULL, MTX_DEF); 572 } 573 574 static vm_object_t 575 swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size, 576 vm_ooffset_t offset) 577 { 578 vm_object_t object; 579 580 if (cred != NULL) { 581 if (!swap_reserve_by_cred(size, cred)) 582 return (NULL); 583 crhold(cred); 584 } 585 object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset + 586 PAGE_MASK + size)); 587 object->handle = handle; 588 if (cred != NULL) { 589 object->cred = cred; 590 object->charge = size; 591 } 592 object->un_pager.swp.swp_bcount = 0; 593 return (object); 594 } 595 596 /* 597 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 598 * its metadata structures. 599 * 600 * This routine is called from the mmap and fork code to create a new 601 * OBJT_SWAP object. 602 * 603 * This routine must ensure that no live duplicate is created for 604 * the named object request, which is protected against by 605 * holding the sw_alloc_sx lock in case handle != NULL. 606 */ 607 static vm_object_t 608 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 609 vm_ooffset_t offset, struct ucred *cred) 610 { 611 vm_object_t object; 612 613 if (handle != NULL) { 614 /* 615 * Reference existing named region or allocate new one. There 616 * should not be a race here against swp_pager_meta_build() 617 * as called from vm_page_remove() in regards to the lookup 618 * of the handle. 619 */ 620 sx_xlock(&sw_alloc_sx); 621 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 622 if (object == NULL) { 623 object = swap_pager_alloc_init(handle, cred, size, 624 offset); 625 if (object != NULL) { 626 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 627 object, pager_object_list); 628 } 629 } 630 sx_xunlock(&sw_alloc_sx); 631 } else { 632 object = swap_pager_alloc_init(handle, cred, size, offset); 633 } 634 return (object); 635 } 636 637 /* 638 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 639 * 640 * The swap backing for the object is destroyed. The code is 641 * designed such that we can reinstantiate it later, but this 642 * routine is typically called only when the entire object is 643 * about to be destroyed. 644 * 645 * The object must be locked. 646 */ 647 static void 648 swap_pager_dealloc(vm_object_t object) 649 { 650 651 VM_OBJECT_ASSERT_WLOCKED(object); 652 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 653 654 /* 655 * Remove from list right away so lookups will fail if we block for 656 * pageout completion. 657 */ 658 if (object->handle != NULL) { 659 VM_OBJECT_WUNLOCK(object); 660 sx_xlock(&sw_alloc_sx); 661 TAILQ_REMOVE(NOBJLIST(object->handle), object, 662 pager_object_list); 663 sx_xunlock(&sw_alloc_sx); 664 VM_OBJECT_WLOCK(object); 665 } 666 667 vm_object_pip_wait(object, "swpdea"); 668 669 /* 670 * Free all remaining metadata. We only bother to free it from 671 * the swap meta data. We do not attempt to free swapblk's still 672 * associated with vm_page_t's for this object. We do not care 673 * if paging is still in progress on some objects. 674 */ 675 swp_pager_meta_free_all(object); 676 object->handle = NULL; 677 object->type = OBJT_DEAD; 678 } 679 680 /************************************************************************ 681 * SWAP PAGER BITMAP ROUTINES * 682 ************************************************************************/ 683 684 /* 685 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 686 * 687 * Allocate swap for the requested number of pages. The starting 688 * swap block number (a page index) is returned or SWAPBLK_NONE 689 * if the allocation failed. 690 * 691 * Also has the side effect of advising that somebody made a mistake 692 * when they configured swap and didn't configure enough. 693 * 694 * This routine may not sleep. 695 * 696 * We allocate in round-robin fashion from the configured devices. 697 */ 698 static daddr_t 699 swp_pager_getswapspace(int npages) 700 { 701 daddr_t blk; 702 struct swdevt *sp; 703 int i; 704 705 blk = SWAPBLK_NONE; 706 mtx_lock(&sw_dev_mtx); 707 sp = swdevhd; 708 for (i = 0; i < nswapdev; i++) { 709 if (sp == NULL) 710 sp = TAILQ_FIRST(&swtailq); 711 if (!(sp->sw_flags & SW_CLOSING)) { 712 blk = blist_alloc(sp->sw_blist, npages); 713 if (blk != SWAPBLK_NONE) { 714 blk += sp->sw_first; 715 sp->sw_used += npages; 716 swap_pager_avail -= npages; 717 swp_sizecheck(); 718 swdevhd = TAILQ_NEXT(sp, sw_list); 719 goto done; 720 } 721 } 722 sp = TAILQ_NEXT(sp, sw_list); 723 } 724 if (swap_pager_full != 2) { 725 printf("swap_pager_getswapspace(%d): failed\n", npages); 726 swap_pager_full = 2; 727 swap_pager_almost_full = 1; 728 } 729 swdevhd = NULL; 730 done: 731 mtx_unlock(&sw_dev_mtx); 732 return (blk); 733 } 734 735 static int 736 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 737 { 738 739 return (blk >= sp->sw_first && blk < sp->sw_end); 740 } 741 742 static void 743 swp_pager_strategy(struct buf *bp) 744 { 745 struct swdevt *sp; 746 747 mtx_lock(&sw_dev_mtx); 748 TAILQ_FOREACH(sp, &swtailq, sw_list) { 749 if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) { 750 mtx_unlock(&sw_dev_mtx); 751 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 752 unmapped_buf_allowed) { 753 bp->b_data = unmapped_buf; 754 bp->b_offset = 0; 755 } else { 756 pmap_qenter((vm_offset_t)bp->b_data, 757 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 758 } 759 sp->sw_strategy(bp, sp); 760 return; 761 } 762 } 763 panic("Swapdev not found"); 764 } 765 766 767 /* 768 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 769 * 770 * This routine returns the specified swap blocks back to the bitmap. 771 * 772 * This routine may not sleep. 773 */ 774 static void 775 swp_pager_freeswapspace(daddr_t blk, int npages) 776 { 777 struct swdevt *sp; 778 779 mtx_lock(&sw_dev_mtx); 780 TAILQ_FOREACH(sp, &swtailq, sw_list) { 781 if (blk >= sp->sw_first && blk < sp->sw_end) { 782 sp->sw_used -= npages; 783 /* 784 * If we are attempting to stop swapping on 785 * this device, we don't want to mark any 786 * blocks free lest they be reused. 787 */ 788 if ((sp->sw_flags & SW_CLOSING) == 0) { 789 blist_free(sp->sw_blist, blk - sp->sw_first, 790 npages); 791 swap_pager_avail += npages; 792 swp_sizecheck(); 793 } 794 mtx_unlock(&sw_dev_mtx); 795 return; 796 } 797 } 798 panic("Swapdev not found"); 799 } 800 801 /* 802 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 803 * range within an object. 804 * 805 * This is a globally accessible routine. 806 * 807 * This routine removes swapblk assignments from swap metadata. 808 * 809 * The external callers of this routine typically have already destroyed 810 * or renamed vm_page_t's associated with this range in the object so 811 * we should be ok. 812 * 813 * The object must be locked. 814 */ 815 void 816 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 817 { 818 819 swp_pager_meta_free(object, start, size); 820 } 821 822 /* 823 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 824 * 825 * Assigns swap blocks to the specified range within the object. The 826 * swap blocks are not zeroed. Any previous swap assignment is destroyed. 827 * 828 * Returns 0 on success, -1 on failure. 829 */ 830 int 831 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 832 { 833 int n = 0; 834 daddr_t blk = SWAPBLK_NONE; 835 vm_pindex_t beg = start; /* save start index */ 836 837 VM_OBJECT_WLOCK(object); 838 while (size) { 839 if (n == 0) { 840 n = BLIST_MAX_ALLOC; 841 while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) { 842 n >>= 1; 843 if (n == 0) { 844 swp_pager_meta_free(object, beg, start - beg); 845 VM_OBJECT_WUNLOCK(object); 846 return (-1); 847 } 848 } 849 } 850 swp_pager_meta_build(object, start, blk); 851 --size; 852 ++start; 853 ++blk; 854 --n; 855 } 856 swp_pager_meta_free(object, start, n); 857 VM_OBJECT_WUNLOCK(object); 858 return (0); 859 } 860 861 /* 862 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 863 * and destroy the source. 864 * 865 * Copy any valid swapblks from the source to the destination. In 866 * cases where both the source and destination have a valid swapblk, 867 * we keep the destination's. 868 * 869 * This routine is allowed to sleep. It may sleep allocating metadata 870 * indirectly through swp_pager_meta_build() or if paging is still in 871 * progress on the source. 872 * 873 * The source object contains no vm_page_t's (which is just as well) 874 * 875 * The source object is of type OBJT_SWAP. 876 * 877 * The source and destination objects must be locked. 878 * Both object locks may temporarily be released. 879 */ 880 void 881 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 882 vm_pindex_t offset, int destroysource) 883 { 884 vm_pindex_t i; 885 886 VM_OBJECT_ASSERT_WLOCKED(srcobject); 887 VM_OBJECT_ASSERT_WLOCKED(dstobject); 888 889 /* 890 * If destroysource is set, we remove the source object from the 891 * swap_pager internal queue now. 892 */ 893 if (destroysource && srcobject->handle != NULL) { 894 vm_object_pip_add(srcobject, 1); 895 VM_OBJECT_WUNLOCK(srcobject); 896 vm_object_pip_add(dstobject, 1); 897 VM_OBJECT_WUNLOCK(dstobject); 898 sx_xlock(&sw_alloc_sx); 899 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 900 pager_object_list); 901 sx_xunlock(&sw_alloc_sx); 902 VM_OBJECT_WLOCK(dstobject); 903 vm_object_pip_wakeup(dstobject); 904 VM_OBJECT_WLOCK(srcobject); 905 vm_object_pip_wakeup(srcobject); 906 } 907 908 /* 909 * transfer source to destination. 910 */ 911 for (i = 0; i < dstobject->size; ++i) { 912 daddr_t dstaddr; 913 914 /* 915 * Locate (without changing) the swapblk on the destination, 916 * unless it is invalid in which case free it silently, or 917 * if the destination is a resident page, in which case the 918 * source is thrown away. 919 */ 920 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 921 922 if (dstaddr == SWAPBLK_NONE) { 923 /* 924 * Destination has no swapblk and is not resident, 925 * copy source. 926 */ 927 daddr_t srcaddr; 928 929 srcaddr = swp_pager_meta_ctl( 930 srcobject, 931 i + offset, 932 SWM_POP 933 ); 934 935 if (srcaddr != SWAPBLK_NONE) { 936 /* 937 * swp_pager_meta_build() can sleep. 938 */ 939 vm_object_pip_add(srcobject, 1); 940 VM_OBJECT_WUNLOCK(srcobject); 941 vm_object_pip_add(dstobject, 1); 942 swp_pager_meta_build(dstobject, i, srcaddr); 943 vm_object_pip_wakeup(dstobject); 944 VM_OBJECT_WLOCK(srcobject); 945 vm_object_pip_wakeup(srcobject); 946 } 947 } else { 948 /* 949 * Destination has valid swapblk or it is represented 950 * by a resident page. We destroy the sourceblock. 951 */ 952 953 swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE); 954 } 955 } 956 957 /* 958 * Free left over swap blocks in source. 959 * 960 * We have to revert the type to OBJT_DEFAULT so we do not accidentally 961 * double-remove the object from the swap queues. 962 */ 963 if (destroysource) { 964 swp_pager_meta_free_all(srcobject); 965 /* 966 * Reverting the type is not necessary, the caller is going 967 * to destroy srcobject directly, but I'm doing it here 968 * for consistency since we've removed the object from its 969 * queues. 970 */ 971 srcobject->type = OBJT_DEFAULT; 972 } 973 } 974 975 /* 976 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 977 * the requested page. 978 * 979 * We determine whether good backing store exists for the requested 980 * page and return TRUE if it does, FALSE if it doesn't. 981 * 982 * If TRUE, we also try to determine how much valid, contiguous backing 983 * store exists before and after the requested page. 984 */ 985 static boolean_t 986 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 987 int *after) 988 { 989 daddr_t blk, blk0; 990 int i; 991 992 VM_OBJECT_ASSERT_LOCKED(object); 993 994 /* 995 * do we have good backing store at the requested index ? 996 */ 997 blk0 = swp_pager_meta_ctl(object, pindex, 0); 998 if (blk0 == SWAPBLK_NONE) { 999 if (before) 1000 *before = 0; 1001 if (after) 1002 *after = 0; 1003 return (FALSE); 1004 } 1005 1006 /* 1007 * find backwards-looking contiguous good backing store 1008 */ 1009 if (before != NULL) { 1010 for (i = 1; i < SWB_NPAGES; i++) { 1011 if (i > pindex) 1012 break; 1013 blk = swp_pager_meta_ctl(object, pindex - i, 0); 1014 if (blk != blk0 - i) 1015 break; 1016 } 1017 *before = i - 1; 1018 } 1019 1020 /* 1021 * find forward-looking contiguous good backing store 1022 */ 1023 if (after != NULL) { 1024 for (i = 1; i < SWB_NPAGES; i++) { 1025 blk = swp_pager_meta_ctl(object, pindex + i, 0); 1026 if (blk != blk0 + i) 1027 break; 1028 } 1029 *after = i - 1; 1030 } 1031 return (TRUE); 1032 } 1033 1034 /* 1035 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1036 * 1037 * This removes any associated swap backing store, whether valid or 1038 * not, from the page. 1039 * 1040 * This routine is typically called when a page is made dirty, at 1041 * which point any associated swap can be freed. MADV_FREE also 1042 * calls us in a special-case situation 1043 * 1044 * NOTE!!! If the page is clean and the swap was valid, the caller 1045 * should make the page dirty before calling this routine. This routine 1046 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1047 * depends on it. 1048 * 1049 * This routine may not sleep. 1050 * 1051 * The object containing the page must be locked. 1052 */ 1053 static void 1054 swap_pager_unswapped(vm_page_t m) 1055 { 1056 1057 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); 1058 } 1059 1060 /* 1061 * swap_pager_getpages() - bring pages in from swap 1062 * 1063 * Attempt to page in the pages in array "m" of length "count". The caller 1064 * may optionally specify that additional pages preceding and succeeding 1065 * the specified range be paged in. The number of such pages is returned 1066 * in the "rbehind" and "rahead" parameters, and they will be in the 1067 * inactive queue upon return. 1068 * 1069 * The pages in "m" must be busied and will remain busied upon return. 1070 */ 1071 static int 1072 swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind, 1073 int *rahead) 1074 { 1075 struct buf *bp; 1076 vm_page_t mpred, msucc, p; 1077 vm_pindex_t pindex; 1078 daddr_t blk; 1079 int i, j, maxahead, maxbehind, reqcount, shift; 1080 1081 reqcount = count; 1082 1083 VM_OBJECT_WUNLOCK(object); 1084 bp = getpbuf(&nsw_rcount); 1085 VM_OBJECT_WLOCK(object); 1086 1087 if (!swap_pager_haspage(object, m[0]->pindex, &maxbehind, &maxahead)) { 1088 relpbuf(bp, &nsw_rcount); 1089 return (VM_PAGER_FAIL); 1090 } 1091 1092 /* 1093 * Clip the readahead and readbehind ranges to exclude resident pages. 1094 */ 1095 if (rahead != NULL) { 1096 KASSERT(reqcount - 1 <= maxahead, 1097 ("page count %d extends beyond swap block", reqcount)); 1098 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1099 pindex = m[reqcount - 1]->pindex; 1100 msucc = TAILQ_NEXT(m[reqcount - 1], listq); 1101 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1102 *rahead = msucc->pindex - pindex - 1; 1103 } 1104 if (rbehind != NULL) { 1105 *rbehind = imin(*rbehind, maxbehind); 1106 pindex = m[0]->pindex; 1107 mpred = TAILQ_PREV(m[0], pglist, listq); 1108 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1109 *rbehind = pindex - mpred->pindex - 1; 1110 } 1111 1112 /* 1113 * Allocate readahead and readbehind pages. 1114 */ 1115 shift = rbehind != NULL ? *rbehind : 0; 1116 if (shift != 0) { 1117 for (i = 1; i <= shift; i++) { 1118 p = vm_page_alloc(object, m[0]->pindex - i, 1119 VM_ALLOC_NORMAL); 1120 if (p == NULL) { 1121 /* Shift allocated pages to the left. */ 1122 for (j = 0; j < i - 1; j++) 1123 bp->b_pages[j] = 1124 bp->b_pages[j + shift - i + 1]; 1125 break; 1126 } 1127 bp->b_pages[shift - i] = p; 1128 } 1129 shift = i - 1; 1130 *rbehind = shift; 1131 } 1132 for (i = 0; i < reqcount; i++) 1133 bp->b_pages[i + shift] = m[i]; 1134 if (rahead != NULL) { 1135 for (i = 0; i < *rahead; i++) { 1136 p = vm_page_alloc(object, 1137 m[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1138 if (p == NULL) 1139 break; 1140 bp->b_pages[shift + reqcount + i] = p; 1141 } 1142 *rahead = i; 1143 } 1144 if (rbehind != NULL) 1145 count += *rbehind; 1146 if (rahead != NULL) 1147 count += *rahead; 1148 1149 vm_object_pip_add(object, count); 1150 1151 for (i = 0; i < count; i++) 1152 bp->b_pages[i]->oflags |= VPO_SWAPINPROG; 1153 1154 pindex = bp->b_pages[0]->pindex; 1155 blk = swp_pager_meta_ctl(object, pindex, 0); 1156 KASSERT(blk != SWAPBLK_NONE, 1157 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1158 1159 VM_OBJECT_WUNLOCK(object); 1160 1161 bp->b_flags |= B_PAGING; 1162 bp->b_iocmd = BIO_READ; 1163 bp->b_iodone = swp_pager_async_iodone; 1164 bp->b_rcred = crhold(thread0.td_ucred); 1165 bp->b_wcred = crhold(thread0.td_ucred); 1166 bp->b_blkno = blk; 1167 bp->b_bcount = PAGE_SIZE * count; 1168 bp->b_bufsize = PAGE_SIZE * count; 1169 bp->b_npages = count; 1170 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1171 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1172 1173 VM_CNT_INC(v_swapin); 1174 VM_CNT_ADD(v_swappgsin, count); 1175 1176 /* 1177 * perform the I/O. NOTE!!! bp cannot be considered valid after 1178 * this point because we automatically release it on completion. 1179 * Instead, we look at the one page we are interested in which we 1180 * still hold a lock on even through the I/O completion. 1181 * 1182 * The other pages in our m[] array are also released on completion, 1183 * so we cannot assume they are valid anymore either. 1184 * 1185 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1186 */ 1187 BUF_KERNPROC(bp); 1188 swp_pager_strategy(bp); 1189 1190 /* 1191 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1192 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1193 * is set in the metadata for each page in the request. 1194 */ 1195 VM_OBJECT_WLOCK(object); 1196 while ((m[0]->oflags & VPO_SWAPINPROG) != 0) { 1197 m[0]->oflags |= VPO_SWAPSLEEP; 1198 VM_CNT_INC(v_intrans); 1199 if (VM_OBJECT_SLEEP(object, &object->paging_in_progress, PSWP, 1200 "swread", hz * 20)) { 1201 printf( 1202 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1203 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1204 } 1205 } 1206 1207 /* 1208 * If we had an unrecoverable read error pages will not be valid. 1209 */ 1210 for (i = 0; i < reqcount; i++) 1211 if (m[i]->valid != VM_PAGE_BITS_ALL) 1212 return (VM_PAGER_ERROR); 1213 1214 return (VM_PAGER_OK); 1215 1216 /* 1217 * A final note: in a low swap situation, we cannot deallocate swap 1218 * and mark a page dirty here because the caller is likely to mark 1219 * the page clean when we return, causing the page to possibly revert 1220 * to all-zero's later. 1221 */ 1222 } 1223 1224 /* 1225 * swap_pager_getpages_async(): 1226 * 1227 * Right now this is emulation of asynchronous operation on top of 1228 * swap_pager_getpages(). 1229 */ 1230 static int 1231 swap_pager_getpages_async(vm_object_t object, vm_page_t *m, int count, 1232 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1233 { 1234 int r, error; 1235 1236 r = swap_pager_getpages(object, m, count, rbehind, rahead); 1237 VM_OBJECT_WUNLOCK(object); 1238 switch (r) { 1239 case VM_PAGER_OK: 1240 error = 0; 1241 break; 1242 case VM_PAGER_ERROR: 1243 error = EIO; 1244 break; 1245 case VM_PAGER_FAIL: 1246 error = EINVAL; 1247 break; 1248 default: 1249 panic("unhandled swap_pager_getpages() error %d", r); 1250 } 1251 (iodone)(arg, m, count, error); 1252 VM_OBJECT_WLOCK(object); 1253 1254 return (r); 1255 } 1256 1257 /* 1258 * swap_pager_putpages: 1259 * 1260 * Assign swap (if necessary) and initiate I/O on the specified pages. 1261 * 1262 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1263 * are automatically converted to SWAP objects. 1264 * 1265 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1266 * vm_page reservation system coupled with properly written VFS devices 1267 * should ensure that no low-memory deadlock occurs. This is an area 1268 * which needs work. 1269 * 1270 * The parent has N vm_object_pip_add() references prior to 1271 * calling us and will remove references for rtvals[] that are 1272 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1273 * completion. 1274 * 1275 * The parent has soft-busy'd the pages it passes us and will unbusy 1276 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1277 * We need to unbusy the rest on I/O completion. 1278 */ 1279 static void 1280 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1281 int flags, int *rtvals) 1282 { 1283 int i, n; 1284 boolean_t sync; 1285 1286 if (count && m[0]->object != object) { 1287 panic("swap_pager_putpages: object mismatch %p/%p", 1288 object, 1289 m[0]->object 1290 ); 1291 } 1292 1293 /* 1294 * Step 1 1295 * 1296 * Turn object into OBJT_SWAP 1297 * check for bogus sysops 1298 * force sync if not pageout process 1299 */ 1300 if (object->type != OBJT_SWAP) 1301 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1302 VM_OBJECT_WUNLOCK(object); 1303 1304 n = 0; 1305 if (curproc != pageproc) 1306 sync = TRUE; 1307 else 1308 sync = (flags & VM_PAGER_PUT_SYNC) != 0; 1309 1310 /* 1311 * Step 2 1312 * 1313 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1314 * The page is left dirty until the pageout operation completes 1315 * successfully. 1316 */ 1317 for (i = 0; i < count; i += n) { 1318 int j; 1319 struct buf *bp; 1320 daddr_t blk; 1321 1322 /* 1323 * Maximum I/O size is limited by a number of factors. 1324 */ 1325 n = min(BLIST_MAX_ALLOC, count - i); 1326 n = min(n, nsw_cluster_max); 1327 1328 /* 1329 * Get biggest block of swap we can. If we fail, fall 1330 * back and try to allocate a smaller block. Don't go 1331 * overboard trying to allocate space if it would overly 1332 * fragment swap. 1333 */ 1334 while ( 1335 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE && 1336 n > 4 1337 ) { 1338 n >>= 1; 1339 } 1340 if (blk == SWAPBLK_NONE) { 1341 for (j = 0; j < n; ++j) 1342 rtvals[i+j] = VM_PAGER_FAIL; 1343 continue; 1344 } 1345 1346 /* 1347 * All I/O parameters have been satisfied, build the I/O 1348 * request and assign the swap space. 1349 */ 1350 if (sync == TRUE) { 1351 bp = getpbuf(&nsw_wcount_sync); 1352 } else { 1353 bp = getpbuf(&nsw_wcount_async); 1354 bp->b_flags = B_ASYNC; 1355 } 1356 bp->b_flags |= B_PAGING; 1357 bp->b_iocmd = BIO_WRITE; 1358 1359 bp->b_rcred = crhold(thread0.td_ucred); 1360 bp->b_wcred = crhold(thread0.td_ucred); 1361 bp->b_bcount = PAGE_SIZE * n; 1362 bp->b_bufsize = PAGE_SIZE * n; 1363 bp->b_blkno = blk; 1364 1365 VM_OBJECT_WLOCK(object); 1366 for (j = 0; j < n; ++j) { 1367 vm_page_t mreq = m[i+j]; 1368 1369 swp_pager_meta_build( 1370 mreq->object, 1371 mreq->pindex, 1372 blk + j 1373 ); 1374 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1375 mreq->oflags |= VPO_SWAPINPROG; 1376 bp->b_pages[j] = mreq; 1377 } 1378 VM_OBJECT_WUNLOCK(object); 1379 bp->b_npages = n; 1380 /* 1381 * Must set dirty range for NFS to work. 1382 */ 1383 bp->b_dirtyoff = 0; 1384 bp->b_dirtyend = bp->b_bcount; 1385 1386 VM_CNT_INC(v_swapout); 1387 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1388 1389 /* 1390 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1391 * can call the async completion routine at the end of a 1392 * synchronous I/O operation. Otherwise, our caller would 1393 * perform duplicate unbusy and wakeup operations on the page 1394 * and object, respectively. 1395 */ 1396 for (j = 0; j < n; j++) 1397 rtvals[i + j] = VM_PAGER_PEND; 1398 1399 /* 1400 * asynchronous 1401 * 1402 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1403 */ 1404 if (sync == FALSE) { 1405 bp->b_iodone = swp_pager_async_iodone; 1406 BUF_KERNPROC(bp); 1407 swp_pager_strategy(bp); 1408 continue; 1409 } 1410 1411 /* 1412 * synchronous 1413 * 1414 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1415 */ 1416 bp->b_iodone = bdone; 1417 swp_pager_strategy(bp); 1418 1419 /* 1420 * Wait for the sync I/O to complete. 1421 */ 1422 bwait(bp, PVM, "swwrt"); 1423 1424 /* 1425 * Now that we are through with the bp, we can call the 1426 * normal async completion, which frees everything up. 1427 */ 1428 swp_pager_async_iodone(bp); 1429 } 1430 VM_OBJECT_WLOCK(object); 1431 } 1432 1433 /* 1434 * swp_pager_async_iodone: 1435 * 1436 * Completion routine for asynchronous reads and writes from/to swap. 1437 * Also called manually by synchronous code to finish up a bp. 1438 * 1439 * This routine may not sleep. 1440 */ 1441 static void 1442 swp_pager_async_iodone(struct buf *bp) 1443 { 1444 int i; 1445 vm_object_t object = NULL; 1446 1447 /* 1448 * report error 1449 */ 1450 if (bp->b_ioflags & BIO_ERROR) { 1451 printf( 1452 "swap_pager: I/O error - %s failed; blkno %ld," 1453 "size %ld, error %d\n", 1454 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1455 (long)bp->b_blkno, 1456 (long)bp->b_bcount, 1457 bp->b_error 1458 ); 1459 } 1460 1461 /* 1462 * remove the mapping for kernel virtual 1463 */ 1464 if (buf_mapped(bp)) 1465 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1466 else 1467 bp->b_data = bp->b_kvabase; 1468 1469 if (bp->b_npages) { 1470 object = bp->b_pages[0]->object; 1471 VM_OBJECT_WLOCK(object); 1472 } 1473 1474 /* 1475 * cleanup pages. If an error occurs writing to swap, we are in 1476 * very serious trouble. If it happens to be a disk error, though, 1477 * we may be able to recover by reassigning the swap later on. So 1478 * in this case we remove the m->swapblk assignment for the page 1479 * but do not free it in the rlist. The errornous block(s) are thus 1480 * never reallocated as swap. Redirty the page and continue. 1481 */ 1482 for (i = 0; i < bp->b_npages; ++i) { 1483 vm_page_t m = bp->b_pages[i]; 1484 1485 m->oflags &= ~VPO_SWAPINPROG; 1486 if (m->oflags & VPO_SWAPSLEEP) { 1487 m->oflags &= ~VPO_SWAPSLEEP; 1488 wakeup(&object->paging_in_progress); 1489 } 1490 1491 if (bp->b_ioflags & BIO_ERROR) { 1492 /* 1493 * If an error occurs I'd love to throw the swapblk 1494 * away without freeing it back to swapspace, so it 1495 * can never be used again. But I can't from an 1496 * interrupt. 1497 */ 1498 if (bp->b_iocmd == BIO_READ) { 1499 /* 1500 * NOTE: for reads, m->dirty will probably 1501 * be overridden by the original caller of 1502 * getpages so don't play cute tricks here. 1503 */ 1504 m->valid = 0; 1505 } else { 1506 /* 1507 * If a write error occurs, reactivate page 1508 * so it doesn't clog the inactive list, 1509 * then finish the I/O. 1510 */ 1511 vm_page_dirty(m); 1512 vm_page_lock(m); 1513 vm_page_activate(m); 1514 vm_page_unlock(m); 1515 vm_page_sunbusy(m); 1516 } 1517 } else if (bp->b_iocmd == BIO_READ) { 1518 /* 1519 * NOTE: for reads, m->dirty will probably be 1520 * overridden by the original caller of getpages so 1521 * we cannot set them in order to free the underlying 1522 * swap in a low-swap situation. I don't think we'd 1523 * want to do that anyway, but it was an optimization 1524 * that existed in the old swapper for a time before 1525 * it got ripped out due to precisely this problem. 1526 */ 1527 KASSERT(!pmap_page_is_mapped(m), 1528 ("swp_pager_async_iodone: page %p is mapped", m)); 1529 KASSERT(m->dirty == 0, 1530 ("swp_pager_async_iodone: page %p is dirty", m)); 1531 1532 m->valid = VM_PAGE_BITS_ALL; 1533 if (i < bp->b_pgbefore || 1534 i >= bp->b_npages - bp->b_pgafter) 1535 vm_page_readahead_finish(m); 1536 } else { 1537 /* 1538 * For write success, clear the dirty 1539 * status, then finish the I/O ( which decrements the 1540 * busy count and possibly wakes waiter's up ). 1541 * A page is only written to swap after a period of 1542 * inactivity. Therefore, we do not expect it to be 1543 * reused. 1544 */ 1545 KASSERT(!pmap_page_is_write_mapped(m), 1546 ("swp_pager_async_iodone: page %p is not write" 1547 " protected", m)); 1548 vm_page_undirty(m); 1549 vm_page_lock(m); 1550 vm_page_deactivate_noreuse(m); 1551 vm_page_unlock(m); 1552 vm_page_sunbusy(m); 1553 } 1554 } 1555 1556 /* 1557 * adjust pip. NOTE: the original parent may still have its own 1558 * pip refs on the object. 1559 */ 1560 if (object != NULL) { 1561 vm_object_pip_wakeupn(object, bp->b_npages); 1562 VM_OBJECT_WUNLOCK(object); 1563 } 1564 1565 /* 1566 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1567 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1568 * trigger a KASSERT in relpbuf(). 1569 */ 1570 if (bp->b_vp) { 1571 bp->b_vp = NULL; 1572 bp->b_bufobj = NULL; 1573 } 1574 /* 1575 * release the physical I/O buffer 1576 */ 1577 relpbuf( 1578 bp, 1579 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount : 1580 ((bp->b_flags & B_ASYNC) ? 1581 &nsw_wcount_async : 1582 &nsw_wcount_sync 1583 ) 1584 ) 1585 ); 1586 } 1587 1588 /* 1589 * swap_pager_isswapped: 1590 * 1591 * Return 1 if at least one page in the given object is paged 1592 * out to the given swap device. 1593 * 1594 * This routine may not sleep. 1595 */ 1596 int 1597 swap_pager_isswapped(vm_object_t object, struct swdevt *sp) 1598 { 1599 daddr_t index = 0; 1600 int bcount; 1601 int i; 1602 1603 VM_OBJECT_ASSERT_WLOCKED(object); 1604 if (object->type != OBJT_SWAP) 1605 return (0); 1606 1607 mtx_lock(&swhash_mtx); 1608 for (bcount = 0; bcount < object->un_pager.swp.swp_bcount; bcount++) { 1609 struct swblock *swap; 1610 1611 if ((swap = *swp_pager_hash(object, index)) != NULL) { 1612 for (i = 0; i < SWAP_META_PAGES; ++i) { 1613 if (swp_pager_isondev(swap->swb_pages[i], sp)) { 1614 mtx_unlock(&swhash_mtx); 1615 return (1); 1616 } 1617 } 1618 } 1619 index += SWAP_META_PAGES; 1620 } 1621 mtx_unlock(&swhash_mtx); 1622 return (0); 1623 } 1624 1625 int 1626 swap_pager_nswapdev(void) 1627 { 1628 1629 return (nswapdev); 1630 } 1631 1632 /* 1633 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in 1634 * 1635 * This routine dissociates the page at the given index within an object 1636 * from its backing store, paging it in if it does not reside in memory. 1637 * If the page is paged in, it is marked dirty and placed in the laundry 1638 * queue. The page is marked dirty because it no longer has backing 1639 * store. It is placed in the laundry queue because it has not been 1640 * accessed recently. Otherwise, it would already reside in memory. 1641 * 1642 * We also attempt to swap in all other pages in the swap block. 1643 * However, we only guarantee that the one at the specified index is 1644 * paged in. 1645 * 1646 * XXX - The code to page the whole block in doesn't work, so we 1647 * revert to the one-by-one behavior for now. Sigh. 1648 */ 1649 static inline void 1650 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex) 1651 { 1652 vm_page_t m; 1653 1654 vm_object_pip_add(object, 1); 1655 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL); 1656 if (m->valid == VM_PAGE_BITS_ALL) { 1657 vm_object_pip_wakeup(object); 1658 vm_page_dirty(m); 1659 vm_page_lock(m); 1660 vm_page_activate(m); 1661 vm_page_unlock(m); 1662 vm_page_xunbusy(m); 1663 vm_pager_page_unswapped(m); 1664 return; 1665 } 1666 1667 if (swap_pager_getpages(object, &m, 1, NULL, NULL) != VM_PAGER_OK) 1668 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/ 1669 vm_object_pip_wakeup(object); 1670 vm_page_dirty(m); 1671 vm_page_lock(m); 1672 vm_page_launder(m); 1673 vm_page_unlock(m); 1674 vm_page_xunbusy(m); 1675 vm_pager_page_unswapped(m); 1676 } 1677 1678 /* 1679 * swap_pager_swapoff: 1680 * 1681 * Page in all of the pages that have been paged out to the 1682 * given device. The corresponding blocks in the bitmap must be 1683 * marked as allocated and the device must be flagged SW_CLOSING. 1684 * There may be no processes swapped out to the device. 1685 * 1686 * This routine may block. 1687 */ 1688 static void 1689 swap_pager_swapoff(struct swdevt *sp) 1690 { 1691 struct swblock *swap; 1692 vm_object_t locked_obj, object; 1693 vm_pindex_t pindex; 1694 int i, j, retries; 1695 1696 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 1697 1698 retries = 0; 1699 locked_obj = NULL; 1700 full_rescan: 1701 mtx_lock(&swhash_mtx); 1702 for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */ 1703 restart: 1704 for (swap = swhash[i]; swap != NULL; swap = swap->swb_hnext) { 1705 object = swap->swb_object; 1706 pindex = swap->swb_index; 1707 for (j = 0; j < SWAP_META_PAGES; ++j) { 1708 if (!swp_pager_isondev(swap->swb_pages[j], sp)) 1709 continue; 1710 if (locked_obj != object) { 1711 if (locked_obj != NULL) 1712 VM_OBJECT_WUNLOCK(locked_obj); 1713 locked_obj = object; 1714 if (!VM_OBJECT_TRYWLOCK(object)) { 1715 mtx_unlock(&swhash_mtx); 1716 /* Depends on type-stability. */ 1717 VM_OBJECT_WLOCK(object); 1718 mtx_lock(&swhash_mtx); 1719 goto restart; 1720 } 1721 } 1722 MPASS(locked_obj == object); 1723 mtx_unlock(&swhash_mtx); 1724 swp_pager_force_pagein(object, pindex + j); 1725 mtx_lock(&swhash_mtx); 1726 goto restart; 1727 } 1728 } 1729 } 1730 mtx_unlock(&swhash_mtx); 1731 if (locked_obj != NULL) { 1732 VM_OBJECT_WUNLOCK(locked_obj); 1733 locked_obj = NULL; 1734 } 1735 if (sp->sw_used) { 1736 /* 1737 * Objects may be locked or paging to the device being 1738 * removed, so we will miss their pages and need to 1739 * make another pass. We have marked this device as 1740 * SW_CLOSING, so the activity should finish soon. 1741 */ 1742 retries++; 1743 if (retries > 100) { 1744 panic("swapoff: failed to locate %d swap blocks", 1745 sp->sw_used); 1746 } 1747 pause("swpoff", hz / 20); 1748 goto full_rescan; 1749 } 1750 EVENTHANDLER_INVOKE(swapoff, sp); 1751 } 1752 1753 /************************************************************************ 1754 * SWAP META DATA * 1755 ************************************************************************ 1756 * 1757 * These routines manipulate the swap metadata stored in the 1758 * OBJT_SWAP object. 1759 * 1760 * Swap metadata is implemented with a global hash and not directly 1761 * linked into the object. Instead the object simply contains 1762 * appropriate tracking counters. 1763 */ 1764 1765 /* 1766 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1767 * 1768 * We first convert the object to a swap object if it is a default 1769 * object. 1770 * 1771 * The specified swapblk is added to the object's swap metadata. If 1772 * the swapblk is not valid, it is freed instead. Any previously 1773 * assigned swapblk is freed. 1774 */ 1775 static void 1776 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1777 { 1778 static volatile int exhausted; 1779 struct swblock *swap; 1780 struct swblock **pswap; 1781 int idx; 1782 1783 VM_OBJECT_ASSERT_WLOCKED(object); 1784 /* 1785 * Convert default object to swap object if necessary 1786 */ 1787 if (object->type != OBJT_SWAP) { 1788 object->type = OBJT_SWAP; 1789 object->un_pager.swp.swp_bcount = 0; 1790 KASSERT(object->handle == NULL, ("default pager with handle")); 1791 } 1792 1793 /* 1794 * Locate hash entry. If not found create, but if we aren't adding 1795 * anything just return. If we run out of space in the map we wait 1796 * and, since the hash table may have changed, retry. 1797 */ 1798 retry: 1799 mtx_lock(&swhash_mtx); 1800 pswap = swp_pager_hash(object, pindex); 1801 1802 if ((swap = *pswap) == NULL) { 1803 int i; 1804 1805 if (swapblk == SWAPBLK_NONE) 1806 goto done; 1807 1808 swap = *pswap = uma_zalloc(swap_zone, M_NOWAIT | 1809 (curproc == pageproc ? M_USE_RESERVE : 0)); 1810 if (swap == NULL) { 1811 mtx_unlock(&swhash_mtx); 1812 VM_OBJECT_WUNLOCK(object); 1813 if (uma_zone_exhausted(swap_zone)) { 1814 if (atomic_cmpset_int(&exhausted, 0, 1)) 1815 printf("swap zone exhausted, " 1816 "increase kern.maxswzone\n"); 1817 vm_pageout_oom(VM_OOM_SWAPZ); 1818 pause("swzonex", 10); 1819 } else 1820 VM_WAIT; 1821 VM_OBJECT_WLOCK(object); 1822 goto retry; 1823 } 1824 1825 if (atomic_cmpset_int(&exhausted, 1, 0)) 1826 printf("swap zone ok\n"); 1827 1828 swap->swb_hnext = NULL; 1829 swap->swb_object = object; 1830 swap->swb_index = pindex & ~(vm_pindex_t)SWAP_META_MASK; 1831 swap->swb_count = 0; 1832 1833 ++object->un_pager.swp.swp_bcount; 1834 1835 for (i = 0; i < SWAP_META_PAGES; ++i) 1836 swap->swb_pages[i] = SWAPBLK_NONE; 1837 } 1838 1839 /* 1840 * Delete prior contents of metadata 1841 */ 1842 idx = pindex & SWAP_META_MASK; 1843 1844 if (swap->swb_pages[idx] != SWAPBLK_NONE) { 1845 swp_pager_freeswapspace(swap->swb_pages[idx], 1); 1846 --swap->swb_count; 1847 } 1848 1849 /* 1850 * Enter block into metadata 1851 */ 1852 swap->swb_pages[idx] = swapblk; 1853 if (swapblk != SWAPBLK_NONE) 1854 ++swap->swb_count; 1855 done: 1856 mtx_unlock(&swhash_mtx); 1857 } 1858 1859 /* 1860 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 1861 * 1862 * The requested range of blocks is freed, with any associated swap 1863 * returned to the swap bitmap. 1864 * 1865 * This routine will free swap metadata structures as they are cleaned 1866 * out. This routine does *NOT* operate on swap metadata associated 1867 * with resident pages. 1868 */ 1869 static void 1870 swp_pager_meta_free(vm_object_t object, vm_pindex_t index, vm_pindex_t count) 1871 { 1872 struct swblock **pswap, *swap; 1873 vm_pindex_t c; 1874 daddr_t v; 1875 int n, sidx; 1876 1877 VM_OBJECT_ASSERT_LOCKED(object); 1878 if (object->type != OBJT_SWAP || count == 0) 1879 return; 1880 1881 mtx_lock(&swhash_mtx); 1882 for (c = 0; c < count;) { 1883 pswap = swp_pager_hash(object, index); 1884 sidx = index & SWAP_META_MASK; 1885 n = SWAP_META_PAGES - sidx; 1886 index += n; 1887 if ((swap = *pswap) == NULL) { 1888 c += n; 1889 continue; 1890 } 1891 for (; c < count && sidx < SWAP_META_PAGES; ++c, ++sidx) { 1892 if ((v = swap->swb_pages[sidx]) == SWAPBLK_NONE) 1893 continue; 1894 swp_pager_freeswapspace(v, 1); 1895 swap->swb_pages[sidx] = SWAPBLK_NONE; 1896 if (--swap->swb_count == 0) { 1897 *pswap = swap->swb_hnext; 1898 uma_zfree(swap_zone, swap); 1899 --object->un_pager.swp.swp_bcount; 1900 c += SWAP_META_PAGES - sidx; 1901 break; 1902 } 1903 } 1904 } 1905 mtx_unlock(&swhash_mtx); 1906 } 1907 1908 /* 1909 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 1910 * 1911 * This routine locates and destroys all swap metadata associated with 1912 * an object. 1913 */ 1914 static void 1915 swp_pager_meta_free_all(vm_object_t object) 1916 { 1917 struct swblock **pswap, *swap; 1918 vm_pindex_t index; 1919 daddr_t v; 1920 int i; 1921 1922 VM_OBJECT_ASSERT_WLOCKED(object); 1923 if (object->type != OBJT_SWAP) 1924 return; 1925 1926 index = 0; 1927 while (object->un_pager.swp.swp_bcount != 0) { 1928 mtx_lock(&swhash_mtx); 1929 pswap = swp_pager_hash(object, index); 1930 if ((swap = *pswap) != NULL) { 1931 for (i = 0; i < SWAP_META_PAGES; ++i) { 1932 v = swap->swb_pages[i]; 1933 if (v != SWAPBLK_NONE) { 1934 --swap->swb_count; 1935 swp_pager_freeswapspace(v, 1); 1936 } 1937 } 1938 if (swap->swb_count != 0) 1939 panic( 1940 "swap_pager_meta_free_all: swb_count != 0"); 1941 *pswap = swap->swb_hnext; 1942 uma_zfree(swap_zone, swap); 1943 --object->un_pager.swp.swp_bcount; 1944 } 1945 mtx_unlock(&swhash_mtx); 1946 index += SWAP_META_PAGES; 1947 } 1948 } 1949 1950 /* 1951 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. 1952 * 1953 * This routine is capable of looking up, popping, or freeing 1954 * swapblk assignments in the swap meta data or in the vm_page_t. 1955 * The routine typically returns the swapblk being looked-up, or popped, 1956 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block 1957 * was invalid. This routine will automatically free any invalid 1958 * meta-data swapblks. 1959 * 1960 * It is not possible to store invalid swapblks in the swap meta data 1961 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking. 1962 * 1963 * When acting on a busy resident page and paging is in progress, we 1964 * have to wait until paging is complete but otherwise can act on the 1965 * busy page. 1966 * 1967 * SWM_FREE remove and free swap block from metadata 1968 * SWM_POP remove from meta data but do not free.. pop it out 1969 */ 1970 static daddr_t 1971 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags) 1972 { 1973 struct swblock **pswap; 1974 struct swblock *swap; 1975 daddr_t r1; 1976 int idx; 1977 1978 VM_OBJECT_ASSERT_LOCKED(object); 1979 /* 1980 * The meta data only exists of the object is OBJT_SWAP 1981 * and even then might not be allocated yet. 1982 */ 1983 if (object->type != OBJT_SWAP) 1984 return (SWAPBLK_NONE); 1985 1986 r1 = SWAPBLK_NONE; 1987 mtx_lock(&swhash_mtx); 1988 pswap = swp_pager_hash(object, pindex); 1989 1990 if ((swap = *pswap) != NULL) { 1991 idx = pindex & SWAP_META_MASK; 1992 r1 = swap->swb_pages[idx]; 1993 1994 if (r1 != SWAPBLK_NONE) { 1995 if (flags & SWM_FREE) { 1996 swp_pager_freeswapspace(r1, 1); 1997 r1 = SWAPBLK_NONE; 1998 } 1999 if (flags & (SWM_FREE|SWM_POP)) { 2000 swap->swb_pages[idx] = SWAPBLK_NONE; 2001 if (--swap->swb_count == 0) { 2002 *pswap = swap->swb_hnext; 2003 uma_zfree(swap_zone, swap); 2004 --object->un_pager.swp.swp_bcount; 2005 } 2006 } 2007 } 2008 } 2009 mtx_unlock(&swhash_mtx); 2010 return (r1); 2011 } 2012 2013 /* 2014 * Returns the least page index which is greater than or equal to the 2015 * parameter pindex and for which there is a swap block allocated. 2016 * Returns object's size if the object's type is not swap or if there 2017 * are no allocated swap blocks for the object after the requested 2018 * pindex. 2019 */ 2020 vm_pindex_t 2021 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2022 { 2023 struct swblock **pswap, *swap; 2024 vm_pindex_t i, j, lim; 2025 int idx; 2026 2027 VM_OBJECT_ASSERT_LOCKED(object); 2028 if (object->type != OBJT_SWAP || object->un_pager.swp.swp_bcount == 0) 2029 return (object->size); 2030 2031 mtx_lock(&swhash_mtx); 2032 for (j = pindex; j < object->size; j = lim) { 2033 pswap = swp_pager_hash(object, j); 2034 lim = rounddown2(j + SWAP_META_PAGES, SWAP_META_PAGES); 2035 if (lim > object->size) 2036 lim = object->size; 2037 if ((swap = *pswap) != NULL) { 2038 for (idx = j & SWAP_META_MASK, i = j; i < lim; 2039 i++, idx++) { 2040 if (swap->swb_pages[idx] != SWAPBLK_NONE) 2041 goto found; 2042 } 2043 } 2044 } 2045 i = object->size; 2046 found: 2047 mtx_unlock(&swhash_mtx); 2048 return (i); 2049 } 2050 2051 /* 2052 * System call swapon(name) enables swapping on device name, 2053 * which must be in the swdevsw. Return EBUSY 2054 * if already swapping on this device. 2055 */ 2056 #ifndef _SYS_SYSPROTO_H_ 2057 struct swapon_args { 2058 char *name; 2059 }; 2060 #endif 2061 2062 /* 2063 * MPSAFE 2064 */ 2065 /* ARGSUSED */ 2066 int 2067 sys_swapon(struct thread *td, struct swapon_args *uap) 2068 { 2069 struct vattr attr; 2070 struct vnode *vp; 2071 struct nameidata nd; 2072 int error; 2073 2074 error = priv_check(td, PRIV_SWAPON); 2075 if (error) 2076 return (error); 2077 2078 sx_xlock(&swdev_syscall_lock); 2079 2080 /* 2081 * Swap metadata may not fit in the KVM if we have physical 2082 * memory of >1GB. 2083 */ 2084 if (swap_zone == NULL) { 2085 error = ENOMEM; 2086 goto done; 2087 } 2088 2089 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2090 uap->name, td); 2091 error = namei(&nd); 2092 if (error) 2093 goto done; 2094 2095 NDFREE(&nd, NDF_ONLY_PNBUF); 2096 vp = nd.ni_vp; 2097 2098 if (vn_isdisk(vp, &error)) { 2099 error = swapongeom(vp); 2100 } else if (vp->v_type == VREG && 2101 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2102 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2103 /* 2104 * Allow direct swapping to NFS regular files in the same 2105 * way that nfs_mountroot() sets up diskless swapping. 2106 */ 2107 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2108 } 2109 2110 if (error) 2111 vrele(vp); 2112 done: 2113 sx_xunlock(&swdev_syscall_lock); 2114 return (error); 2115 } 2116 2117 /* 2118 * Check that the total amount of swap currently configured does not 2119 * exceed half the theoretical maximum. If it does, print a warning 2120 * message and return -1; otherwise, return 0. 2121 */ 2122 static int 2123 swapon_check_swzone(unsigned long npages) 2124 { 2125 unsigned long maxpages; 2126 2127 /* absolute maximum we can handle assuming 100% efficiency */ 2128 maxpages = uma_zone_get_max(swap_zone) * SWAP_META_PAGES; 2129 2130 /* recommend using no more than half that amount */ 2131 if (npages > maxpages / 2) { 2132 printf("warning: total configured swap (%lu pages) " 2133 "exceeds maximum recommended amount (%lu pages).\n", 2134 npages, maxpages / 2); 2135 printf("warning: increase kern.maxswzone " 2136 "or reduce amount of swap.\n"); 2137 return (-1); 2138 } 2139 return (0); 2140 } 2141 2142 static void 2143 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2144 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2145 { 2146 struct swdevt *sp, *tsp; 2147 swblk_t dvbase; 2148 u_long mblocks; 2149 2150 /* 2151 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2152 * First chop nblks off to page-align it, then convert. 2153 * 2154 * sw->sw_nblks is in page-sized chunks now too. 2155 */ 2156 nblks &= ~(ctodb(1) - 1); 2157 nblks = dbtoc(nblks); 2158 2159 /* 2160 * If we go beyond this, we get overflows in the radix 2161 * tree bitmap code. 2162 */ 2163 mblocks = 0x40000000 / BLIST_META_RADIX; 2164 if (nblks > mblocks) { 2165 printf( 2166 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2167 mblocks / 1024 / 1024 * PAGE_SIZE); 2168 nblks = mblocks; 2169 } 2170 2171 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2172 sp->sw_vp = vp; 2173 sp->sw_id = id; 2174 sp->sw_dev = dev; 2175 sp->sw_flags = 0; 2176 sp->sw_nblks = nblks; 2177 sp->sw_used = 0; 2178 sp->sw_strategy = strategy; 2179 sp->sw_close = close; 2180 sp->sw_flags = flags; 2181 2182 sp->sw_blist = blist_create(nblks, M_WAITOK); 2183 /* 2184 * Do not free the first two block in order to avoid overwriting 2185 * any bsd label at the front of the partition 2186 */ 2187 blist_free(sp->sw_blist, 2, nblks - 2); 2188 2189 dvbase = 0; 2190 mtx_lock(&sw_dev_mtx); 2191 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2192 if (tsp->sw_end >= dvbase) { 2193 /* 2194 * We put one uncovered page between the devices 2195 * in order to definitively prevent any cross-device 2196 * I/O requests 2197 */ 2198 dvbase = tsp->sw_end + 1; 2199 } 2200 } 2201 sp->sw_first = dvbase; 2202 sp->sw_end = dvbase + nblks; 2203 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2204 nswapdev++; 2205 swap_pager_avail += nblks - 2; 2206 swap_total += (vm_ooffset_t)nblks * PAGE_SIZE; 2207 swapon_check_swzone(swap_total / PAGE_SIZE); 2208 swp_sizecheck(); 2209 mtx_unlock(&sw_dev_mtx); 2210 EVENTHANDLER_INVOKE(swapon, sp); 2211 } 2212 2213 /* 2214 * SYSCALL: swapoff(devname) 2215 * 2216 * Disable swapping on the given device. 2217 * 2218 * XXX: Badly designed system call: it should use a device index 2219 * rather than filename as specification. We keep sw_vp around 2220 * only to make this work. 2221 */ 2222 #ifndef _SYS_SYSPROTO_H_ 2223 struct swapoff_args { 2224 char *name; 2225 }; 2226 #endif 2227 2228 /* 2229 * MPSAFE 2230 */ 2231 /* ARGSUSED */ 2232 int 2233 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2234 { 2235 struct vnode *vp; 2236 struct nameidata nd; 2237 struct swdevt *sp; 2238 int error; 2239 2240 error = priv_check(td, PRIV_SWAPOFF); 2241 if (error) 2242 return (error); 2243 2244 sx_xlock(&swdev_syscall_lock); 2245 2246 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2247 td); 2248 error = namei(&nd); 2249 if (error) 2250 goto done; 2251 NDFREE(&nd, NDF_ONLY_PNBUF); 2252 vp = nd.ni_vp; 2253 2254 mtx_lock(&sw_dev_mtx); 2255 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2256 if (sp->sw_vp == vp) 2257 break; 2258 } 2259 mtx_unlock(&sw_dev_mtx); 2260 if (sp == NULL) { 2261 error = EINVAL; 2262 goto done; 2263 } 2264 error = swapoff_one(sp, td->td_ucred); 2265 done: 2266 sx_xunlock(&swdev_syscall_lock); 2267 return (error); 2268 } 2269 2270 static int 2271 swapoff_one(struct swdevt *sp, struct ucred *cred) 2272 { 2273 u_long nblks; 2274 #ifdef MAC 2275 int error; 2276 #endif 2277 2278 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2279 #ifdef MAC 2280 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2281 error = mac_system_check_swapoff(cred, sp->sw_vp); 2282 (void) VOP_UNLOCK(sp->sw_vp, 0); 2283 if (error != 0) 2284 return (error); 2285 #endif 2286 nblks = sp->sw_nblks; 2287 2288 /* 2289 * We can turn off this swap device safely only if the 2290 * available virtual memory in the system will fit the amount 2291 * of data we will have to page back in, plus an epsilon so 2292 * the system doesn't become critically low on swap space. 2293 */ 2294 if (vm_cnt.v_free_count + swap_pager_avail < nblks + nswap_lowat) 2295 return (ENOMEM); 2296 2297 /* 2298 * Prevent further allocations on this device. 2299 */ 2300 mtx_lock(&sw_dev_mtx); 2301 sp->sw_flags |= SW_CLOSING; 2302 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2303 swap_total -= (vm_ooffset_t)nblks * PAGE_SIZE; 2304 mtx_unlock(&sw_dev_mtx); 2305 2306 /* 2307 * Page in the contents of the device and close it. 2308 */ 2309 swap_pager_swapoff(sp); 2310 2311 sp->sw_close(curthread, sp); 2312 mtx_lock(&sw_dev_mtx); 2313 sp->sw_id = NULL; 2314 TAILQ_REMOVE(&swtailq, sp, sw_list); 2315 nswapdev--; 2316 if (nswapdev == 0) { 2317 swap_pager_full = 2; 2318 swap_pager_almost_full = 1; 2319 } 2320 if (swdevhd == sp) 2321 swdevhd = NULL; 2322 mtx_unlock(&sw_dev_mtx); 2323 blist_destroy(sp->sw_blist); 2324 free(sp, M_VMPGDATA); 2325 return (0); 2326 } 2327 2328 void 2329 swapoff_all(void) 2330 { 2331 struct swdevt *sp, *spt; 2332 const char *devname; 2333 int error; 2334 2335 sx_xlock(&swdev_syscall_lock); 2336 2337 mtx_lock(&sw_dev_mtx); 2338 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2339 mtx_unlock(&sw_dev_mtx); 2340 if (vn_isdisk(sp->sw_vp, NULL)) 2341 devname = devtoname(sp->sw_vp->v_rdev); 2342 else 2343 devname = "[file]"; 2344 error = swapoff_one(sp, thread0.td_ucred); 2345 if (error != 0) { 2346 printf("Cannot remove swap device %s (error=%d), " 2347 "skipping.\n", devname, error); 2348 } else if (bootverbose) { 2349 printf("Swap device %s removed.\n", devname); 2350 } 2351 mtx_lock(&sw_dev_mtx); 2352 } 2353 mtx_unlock(&sw_dev_mtx); 2354 2355 sx_xunlock(&swdev_syscall_lock); 2356 } 2357 2358 void 2359 swap_pager_status(int *total, int *used) 2360 { 2361 struct swdevt *sp; 2362 2363 *total = 0; 2364 *used = 0; 2365 mtx_lock(&sw_dev_mtx); 2366 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2367 *total += sp->sw_nblks; 2368 *used += sp->sw_used; 2369 } 2370 mtx_unlock(&sw_dev_mtx); 2371 } 2372 2373 int 2374 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2375 { 2376 struct swdevt *sp; 2377 const char *tmp_devname; 2378 int error, n; 2379 2380 n = 0; 2381 error = ENOENT; 2382 mtx_lock(&sw_dev_mtx); 2383 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2384 if (n != name) { 2385 n++; 2386 continue; 2387 } 2388 xs->xsw_version = XSWDEV_VERSION; 2389 xs->xsw_dev = sp->sw_dev; 2390 xs->xsw_flags = sp->sw_flags; 2391 xs->xsw_nblks = sp->sw_nblks; 2392 xs->xsw_used = sp->sw_used; 2393 if (devname != NULL) { 2394 if (vn_isdisk(sp->sw_vp, NULL)) 2395 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2396 else 2397 tmp_devname = "[file]"; 2398 strncpy(devname, tmp_devname, len); 2399 } 2400 error = 0; 2401 break; 2402 } 2403 mtx_unlock(&sw_dev_mtx); 2404 return (error); 2405 } 2406 2407 #if defined(COMPAT_FREEBSD11) 2408 #define XSWDEV_VERSION_11 1 2409 struct xswdev11 { 2410 u_int xsw_version; 2411 uint32_t xsw_dev; 2412 int xsw_flags; 2413 int xsw_nblks; 2414 int xsw_used; 2415 }; 2416 #endif 2417 2418 static int 2419 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2420 { 2421 struct xswdev xs; 2422 #if defined(COMPAT_FREEBSD11) 2423 struct xswdev11 xs11; 2424 #endif 2425 int error; 2426 2427 if (arg2 != 1) /* name length */ 2428 return (EINVAL); 2429 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2430 if (error != 0) 2431 return (error); 2432 #if defined(COMPAT_FREEBSD11) 2433 if (req->oldlen == sizeof(xs11)) { 2434 xs11.xsw_version = XSWDEV_VERSION_11; 2435 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2436 xs11.xsw_flags = xs.xsw_flags; 2437 xs11.xsw_nblks = xs.xsw_nblks; 2438 xs11.xsw_used = xs.xsw_used; 2439 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2440 } else 2441 #endif 2442 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2443 return (error); 2444 } 2445 2446 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2447 "Number of swap devices"); 2448 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2449 sysctl_vm_swap_info, 2450 "Swap statistics by device"); 2451 2452 /* 2453 * vmspace_swap_count() - count the approximate swap usage in pages for a 2454 * vmspace. 2455 * 2456 * The map must be locked. 2457 * 2458 * Swap usage is determined by taking the proportional swap used by 2459 * VM objects backing the VM map. To make up for fractional losses, 2460 * if the VM object has any swap use at all the associated map entries 2461 * count for at least 1 swap page. 2462 */ 2463 long 2464 vmspace_swap_count(struct vmspace *vmspace) 2465 { 2466 vm_map_t map; 2467 vm_map_entry_t cur; 2468 vm_object_t object; 2469 long count, n; 2470 2471 map = &vmspace->vm_map; 2472 count = 0; 2473 2474 for (cur = map->header.next; cur != &map->header; cur = cur->next) { 2475 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 && 2476 (object = cur->object.vm_object) != NULL) { 2477 VM_OBJECT_WLOCK(object); 2478 if (object->type == OBJT_SWAP && 2479 object->un_pager.swp.swp_bcount != 0) { 2480 n = (cur->end - cur->start) / PAGE_SIZE; 2481 count += object->un_pager.swp.swp_bcount * 2482 SWAP_META_PAGES * n / object->size + 1; 2483 } 2484 VM_OBJECT_WUNLOCK(object); 2485 } 2486 } 2487 return (count); 2488 } 2489 2490 /* 2491 * GEOM backend 2492 * 2493 * Swapping onto disk devices. 2494 * 2495 */ 2496 2497 static g_orphan_t swapgeom_orphan; 2498 2499 static struct g_class g_swap_class = { 2500 .name = "SWAP", 2501 .version = G_VERSION, 2502 .orphan = swapgeom_orphan, 2503 }; 2504 2505 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2506 2507 2508 static void 2509 swapgeom_close_ev(void *arg, int flags) 2510 { 2511 struct g_consumer *cp; 2512 2513 cp = arg; 2514 g_access(cp, -1, -1, 0); 2515 g_detach(cp); 2516 g_destroy_consumer(cp); 2517 } 2518 2519 /* 2520 * Add a reference to the g_consumer for an inflight transaction. 2521 */ 2522 static void 2523 swapgeom_acquire(struct g_consumer *cp) 2524 { 2525 2526 mtx_assert(&sw_dev_mtx, MA_OWNED); 2527 cp->index++; 2528 } 2529 2530 /* 2531 * Remove a reference from the g_consumer. Post a close event if all 2532 * references go away, since the function might be called from the 2533 * biodone context. 2534 */ 2535 static void 2536 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2537 { 2538 2539 mtx_assert(&sw_dev_mtx, MA_OWNED); 2540 cp->index--; 2541 if (cp->index == 0) { 2542 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2543 sp->sw_id = NULL; 2544 } 2545 } 2546 2547 static void 2548 swapgeom_done(struct bio *bp2) 2549 { 2550 struct swdevt *sp; 2551 struct buf *bp; 2552 struct g_consumer *cp; 2553 2554 bp = bp2->bio_caller2; 2555 cp = bp2->bio_from; 2556 bp->b_ioflags = bp2->bio_flags; 2557 if (bp2->bio_error) 2558 bp->b_ioflags |= BIO_ERROR; 2559 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2560 bp->b_error = bp2->bio_error; 2561 bufdone(bp); 2562 sp = bp2->bio_caller1; 2563 mtx_lock(&sw_dev_mtx); 2564 swapgeom_release(cp, sp); 2565 mtx_unlock(&sw_dev_mtx); 2566 g_destroy_bio(bp2); 2567 } 2568 2569 static void 2570 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2571 { 2572 struct bio *bio; 2573 struct g_consumer *cp; 2574 2575 mtx_lock(&sw_dev_mtx); 2576 cp = sp->sw_id; 2577 if (cp == NULL) { 2578 mtx_unlock(&sw_dev_mtx); 2579 bp->b_error = ENXIO; 2580 bp->b_ioflags |= BIO_ERROR; 2581 bufdone(bp); 2582 return; 2583 } 2584 swapgeom_acquire(cp); 2585 mtx_unlock(&sw_dev_mtx); 2586 if (bp->b_iocmd == BIO_WRITE) 2587 bio = g_new_bio(); 2588 else 2589 bio = g_alloc_bio(); 2590 if (bio == NULL) { 2591 mtx_lock(&sw_dev_mtx); 2592 swapgeom_release(cp, sp); 2593 mtx_unlock(&sw_dev_mtx); 2594 bp->b_error = ENOMEM; 2595 bp->b_ioflags |= BIO_ERROR; 2596 bufdone(bp); 2597 return; 2598 } 2599 2600 bio->bio_caller1 = sp; 2601 bio->bio_caller2 = bp; 2602 bio->bio_cmd = bp->b_iocmd; 2603 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2604 bio->bio_length = bp->b_bcount; 2605 bio->bio_done = swapgeom_done; 2606 if (!buf_mapped(bp)) { 2607 bio->bio_ma = bp->b_pages; 2608 bio->bio_data = unmapped_buf; 2609 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2610 bio->bio_ma_n = bp->b_npages; 2611 bio->bio_flags |= BIO_UNMAPPED; 2612 } else { 2613 bio->bio_data = bp->b_data; 2614 bio->bio_ma = NULL; 2615 } 2616 g_io_request(bio, cp); 2617 return; 2618 } 2619 2620 static void 2621 swapgeom_orphan(struct g_consumer *cp) 2622 { 2623 struct swdevt *sp; 2624 int destroy; 2625 2626 mtx_lock(&sw_dev_mtx); 2627 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2628 if (sp->sw_id == cp) { 2629 sp->sw_flags |= SW_CLOSING; 2630 break; 2631 } 2632 } 2633 /* 2634 * Drop reference we were created with. Do directly since we're in a 2635 * special context where we don't have to queue the call to 2636 * swapgeom_close_ev(). 2637 */ 2638 cp->index--; 2639 destroy = ((sp != NULL) && (cp->index == 0)); 2640 if (destroy) 2641 sp->sw_id = NULL; 2642 mtx_unlock(&sw_dev_mtx); 2643 if (destroy) 2644 swapgeom_close_ev(cp, 0); 2645 } 2646 2647 static void 2648 swapgeom_close(struct thread *td, struct swdevt *sw) 2649 { 2650 struct g_consumer *cp; 2651 2652 mtx_lock(&sw_dev_mtx); 2653 cp = sw->sw_id; 2654 sw->sw_id = NULL; 2655 mtx_unlock(&sw_dev_mtx); 2656 2657 /* 2658 * swapgeom_close() may be called from the biodone context, 2659 * where we cannot perform topology changes. Delegate the 2660 * work to the events thread. 2661 */ 2662 if (cp != NULL) 2663 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2664 } 2665 2666 static int 2667 swapongeom_locked(struct cdev *dev, struct vnode *vp) 2668 { 2669 struct g_provider *pp; 2670 struct g_consumer *cp; 2671 static struct g_geom *gp; 2672 struct swdevt *sp; 2673 u_long nblks; 2674 int error; 2675 2676 pp = g_dev_getprovider(dev); 2677 if (pp == NULL) 2678 return (ENODEV); 2679 mtx_lock(&sw_dev_mtx); 2680 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2681 cp = sp->sw_id; 2682 if (cp != NULL && cp->provider == pp) { 2683 mtx_unlock(&sw_dev_mtx); 2684 return (EBUSY); 2685 } 2686 } 2687 mtx_unlock(&sw_dev_mtx); 2688 if (gp == NULL) 2689 gp = g_new_geomf(&g_swap_class, "swap"); 2690 cp = g_new_consumer(gp); 2691 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2692 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2693 g_attach(cp, pp); 2694 /* 2695 * XXX: Every time you think you can improve the margin for 2696 * footshooting, somebody depends on the ability to do so: 2697 * savecore(8) wants to write to our swapdev so we cannot 2698 * set an exclusive count :-( 2699 */ 2700 error = g_access(cp, 1, 1, 0); 2701 if (error != 0) { 2702 g_detach(cp); 2703 g_destroy_consumer(cp); 2704 return (error); 2705 } 2706 nblks = pp->mediasize / DEV_BSIZE; 2707 swaponsomething(vp, cp, nblks, swapgeom_strategy, 2708 swapgeom_close, dev2udev(dev), 2709 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2710 return (0); 2711 } 2712 2713 static int 2714 swapongeom(struct vnode *vp) 2715 { 2716 int error; 2717 2718 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2719 if (vp->v_type != VCHR || (vp->v_iflag & VI_DOOMED) != 0) { 2720 error = ENOENT; 2721 } else { 2722 g_topology_lock(); 2723 error = swapongeom_locked(vp->v_rdev, vp); 2724 g_topology_unlock(); 2725 } 2726 VOP_UNLOCK(vp, 0); 2727 return (error); 2728 } 2729 2730 /* 2731 * VNODE backend 2732 * 2733 * This is used mainly for network filesystem (read: probably only tested 2734 * with NFS) swapfiles. 2735 * 2736 */ 2737 2738 static void 2739 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2740 { 2741 struct vnode *vp2; 2742 2743 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2744 2745 vp2 = sp->sw_id; 2746 vhold(vp2); 2747 if (bp->b_iocmd == BIO_WRITE) { 2748 if (bp->b_bufobj) 2749 bufobj_wdrop(bp->b_bufobj); 2750 bufobj_wref(&vp2->v_bufobj); 2751 } 2752 if (bp->b_bufobj != &vp2->v_bufobj) 2753 bp->b_bufobj = &vp2->v_bufobj; 2754 bp->b_vp = vp2; 2755 bp->b_iooffset = dbtob(bp->b_blkno); 2756 bstrategy(bp); 2757 return; 2758 } 2759 2760 static void 2761 swapdev_close(struct thread *td, struct swdevt *sp) 2762 { 2763 2764 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2765 vrele(sp->sw_vp); 2766 } 2767 2768 2769 static int 2770 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2771 { 2772 struct swdevt *sp; 2773 int error; 2774 2775 if (nblks == 0) 2776 return (ENXIO); 2777 mtx_lock(&sw_dev_mtx); 2778 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2779 if (sp->sw_id == vp) { 2780 mtx_unlock(&sw_dev_mtx); 2781 return (EBUSY); 2782 } 2783 } 2784 mtx_unlock(&sw_dev_mtx); 2785 2786 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2787 #ifdef MAC 2788 error = mac_system_check_swapon(td->td_ucred, vp); 2789 if (error == 0) 2790 #endif 2791 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 2792 (void) VOP_UNLOCK(vp, 0); 2793 if (error) 2794 return (error); 2795 2796 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 2797 NODEV, 0); 2798 return (0); 2799 } 2800 2801 static int 2802 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 2803 { 2804 int error, new, n; 2805 2806 new = nsw_wcount_async_max; 2807 error = sysctl_handle_int(oidp, &new, 0, req); 2808 if (error != 0 || req->newptr == NULL) 2809 return (error); 2810 2811 if (new > nswbuf / 2 || new < 1) 2812 return (EINVAL); 2813 2814 mtx_lock(&pbuf_mtx); 2815 while (nsw_wcount_async_max != new) { 2816 /* 2817 * Adjust difference. If the current async count is too low, 2818 * we will need to sqeeze our update slowly in. Sleep with a 2819 * higher priority than getpbuf() to finish faster. 2820 */ 2821 n = new - nsw_wcount_async_max; 2822 if (nsw_wcount_async + n >= 0) { 2823 nsw_wcount_async += n; 2824 nsw_wcount_async_max += n; 2825 wakeup(&nsw_wcount_async); 2826 } else { 2827 nsw_wcount_async_max -= nsw_wcount_async; 2828 nsw_wcount_async = 0; 2829 msleep(&nsw_wcount_async, &pbuf_mtx, PSWP, 2830 "swpsysctl", 0); 2831 } 2832 } 2833 mtx_unlock(&pbuf_mtx); 2834 2835 return (0); 2836 } 2837