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_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) 140 141 struct 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 }; 148 149 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); 150 static struct mtx sw_dev_mtx; 151 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 152 static struct swdevt *swdevhd; /* Allocate from here next */ 153 static int nswapdev; /* Number of swap devices */ 154 int swap_pager_avail; 155 static int swdev_syscall_active = 0; /* serialize swap(on|off) */ 156 157 static vm_ooffset_t swap_total; 158 SYSCTL_QUAD(_vm, OID_AUTO, swap_total, CTLFLAG_RD, &swap_total, 0, 159 "Total amount of available swap storage."); 160 static vm_ooffset_t swap_reserved; 161 SYSCTL_QUAD(_vm, OID_AUTO, swap_reserved, CTLFLAG_RD, &swap_reserved, 0, 162 "Amount of swap storage needed to back all allocated anonymous memory."); 163 static int overcommit = 0; 164 SYSCTL_INT(_vm, OID_AUTO, overcommit, CTLFLAG_RW, &overcommit, 0, 165 "Configure virtual memory overcommit behavior. See tuning(7) " 166 "for details."); 167 static unsigned long swzone; 168 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 169 "Actual size of swap metadata zone"); 170 static unsigned long swap_maxpages; 171 SYSCTL_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) 178 179 int 180 swap_reserve(vm_ooffset_t incr) 181 { 182 183 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 184 } 185 186 int 187 swap_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 = vm_cnt.v_page_count - vm_cnt.v_free_reserved - vm_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 } 258 259 void 260 swap_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 } 281 282 void 283 swap_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 } 292 293 void 294 swap_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 } 317 318 static void swapdev_strategy(struct buf *, struct swdevt *sw); 319 320 #define SWM_FREE 0x02 /* free, period */ 321 #define SWM_POP 0x04 /* pop out */ 322 323 int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 324 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 325 static int nsw_rcount; /* free read buffers */ 326 static int nsw_wcount_sync; /* limit write buffers / synchronous */ 327 static int nsw_wcount_async; /* limit write buffers / asynchronous */ 328 static int nsw_wcount_async_max;/* assigned maximum */ 329 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 330 331 static struct swblock **swhash; 332 static int swhash_mask; 333 static struct mtx swhash_mtx; 334 335 static int swap_async_max = 4; /* maximum in-progress async I/O's */ 336 static struct sx sw_alloc_sx; 337 338 339 SYSCTL_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)]) 351 352 static struct mtx sw_alloc_mtx; /* protect list manipulation */ 353 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 354 static 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 */ 361 static vm_object_t 362 swap_pager_alloc(void *handle, vm_ooffset_t size, 363 vm_prot_t prot, vm_ooffset_t offset, struct ucred *); 364 static void swap_pager_dealloc(vm_object_t object); 365 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int); 366 static int swap_pager_getpages_async(vm_object_t, vm_page_t *, int, int, 367 pgo_getpages_iodone_t, void *); 368 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 369 static boolean_t 370 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 371 static void swap_pager_init(void); 372 static void swap_pager_unswapped(vm_page_t); 373 static void swap_pager_swapoff(struct swdevt *sp); 374 375 struct pagerops swappagerops = { 376 .pgo_init = swap_pager_init, /* early system initialization of pager */ 377 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 378 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 379 .pgo_getpages = swap_pager_getpages, /* pagein */ 380 .pgo_getpages_async = swap_pager_getpages_async, /* pagein (async) */ 381 .pgo_putpages = swap_pager_putpages, /* pageout */ 382 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 383 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 384 }; 385 386 /* 387 * dmmax is in page-sized chunks with the new swap system. It was 388 * dev-bsized chunks in the old. dmmax is always a power of 2. 389 * 390 * swap_*() routines are externally accessible. swp_*() routines are 391 * internal. 392 */ 393 static int dmmax; 394 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 395 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 396 397 SYSCTL_INT(_vm, OID_AUTO, dmmax, 398 CTLFLAG_RD, &dmmax, 0, "Maximum size of a swap block"); 399 400 static void swp_sizecheck(void); 401 static void swp_pager_async_iodone(struct buf *bp); 402 static int swapongeom(struct thread *, struct vnode *); 403 static int swaponvp(struct thread *, struct vnode *, u_long); 404 static int swapoff_one(struct swdevt *sp, struct ucred *cred); 405 406 /* 407 * Swap bitmap functions 408 */ 409 static void swp_pager_freeswapspace(daddr_t blk, int npages); 410 static daddr_t swp_pager_getswapspace(int npages); 411 412 /* 413 * Metadata functions 414 */ 415 static struct swblock **swp_pager_hash(vm_object_t object, vm_pindex_t index); 416 static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 417 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, daddr_t); 418 static void swp_pager_meta_free_all(vm_object_t); 419 static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 420 421 static void 422 swp_pager_free_nrpage(vm_page_t m) 423 { 424 425 vm_page_lock(m); 426 if (m->wire_count == 0) 427 vm_page_free(m); 428 vm_page_unlock(m); 429 } 430 431 /* 432 * SWP_SIZECHECK() - update swap_pager_full indication 433 * 434 * update the swap_pager_almost_full indication and warn when we are 435 * about to run out of swap space, using lowat/hiwat hysteresis. 436 * 437 * Clear swap_pager_full ( task killing ) indication when lowat is met. 438 * 439 * No restrictions on call 440 * This routine may not block. 441 */ 442 static void 443 swp_sizecheck(void) 444 { 445 446 if (swap_pager_avail < nswap_lowat) { 447 if (swap_pager_almost_full == 0) { 448 printf("swap_pager: out of swap space\n"); 449 swap_pager_almost_full = 1; 450 } 451 } else { 452 swap_pager_full = 0; 453 if (swap_pager_avail > nswap_hiwat) 454 swap_pager_almost_full = 0; 455 } 456 } 457 458 /* 459 * SWP_PAGER_HASH() - hash swap meta data 460 * 461 * This is an helper function which hashes the swapblk given 462 * the object and page index. It returns a pointer to a pointer 463 * to the object, or a pointer to a NULL pointer if it could not 464 * find a swapblk. 465 */ 466 static struct swblock ** 467 swp_pager_hash(vm_object_t object, vm_pindex_t index) 468 { 469 struct swblock **pswap; 470 struct swblock *swap; 471 472 index &= ~(vm_pindex_t)SWAP_META_MASK; 473 pswap = &swhash[(index ^ (int)(intptr_t)object) & swhash_mask]; 474 while ((swap = *pswap) != NULL) { 475 if (swap->swb_object == object && 476 swap->swb_index == index 477 ) { 478 break; 479 } 480 pswap = &swap->swb_hnext; 481 } 482 return (pswap); 483 } 484 485 /* 486 * SWAP_PAGER_INIT() - initialize the swap pager! 487 * 488 * Expected to be started from system init. NOTE: This code is run 489 * before much else so be careful what you depend on. Most of the VM 490 * system has yet to be initialized at this point. 491 */ 492 static void 493 swap_pager_init(void) 494 { 495 /* 496 * Initialize object lists 497 */ 498 int i; 499 500 for (i = 0; i < NOBJLISTS; ++i) 501 TAILQ_INIT(&swap_pager_object_list[i]); 502 mtx_init(&sw_alloc_mtx, "swap_pager list", NULL, MTX_DEF); 503 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 504 505 /* 506 * Device Stripe, in PAGE_SIZE'd blocks 507 */ 508 dmmax = SWB_NPAGES * 2; 509 } 510 511 /* 512 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 513 * 514 * Expected to be started from pageout process once, prior to entering 515 * its main loop. 516 */ 517 void 518 swap_pager_swap_init(void) 519 { 520 unsigned long n, n2; 521 522 /* 523 * Number of in-transit swap bp operations. Don't 524 * exhaust the pbufs completely. Make sure we 525 * initialize workable values (0 will work for hysteresis 526 * but it isn't very efficient). 527 * 528 * The nsw_cluster_max is constrained by the bp->b_pages[] 529 * array (MAXPHYS/PAGE_SIZE) and our locally defined 530 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 531 * constrained by the swap device interleave stripe size. 532 * 533 * Currently we hardwire nsw_wcount_async to 4. This limit is 534 * designed to prevent other I/O from having high latencies due to 535 * our pageout I/O. The value 4 works well for one or two active swap 536 * devices but is probably a little low if you have more. Even so, 537 * a higher value would probably generate only a limited improvement 538 * with three or four active swap devices since the system does not 539 * typically have to pageout at extreme bandwidths. We will want 540 * at least 2 per swap devices, and 4 is a pretty good value if you 541 * have one NFS swap device due to the command/ack latency over NFS. 542 * So it all works out pretty well. 543 */ 544 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER); 545 546 mtx_lock(&pbuf_mtx); 547 nsw_rcount = (nswbuf + 1) / 2; 548 nsw_wcount_sync = (nswbuf + 3) / 4; 549 nsw_wcount_async = 4; 550 nsw_wcount_async_max = nsw_wcount_async; 551 mtx_unlock(&pbuf_mtx); 552 553 /* 554 * Initialize our zone. Right now I'm just guessing on the number 555 * we need based on the number of pages in the system. Each swblock 556 * can hold 32 pages, so this is probably overkill. This reservation 557 * is typically limited to around 32MB by default. 558 */ 559 n = vm_cnt.v_page_count / 2; 560 if (maxswzone && n > maxswzone / sizeof(struct swblock)) 561 n = maxswzone / sizeof(struct swblock); 562 n2 = n; 563 swap_zone = uma_zcreate("SWAPMETA", sizeof(struct swblock), NULL, NULL, 564 NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE | UMA_ZONE_VM); 565 if (swap_zone == NULL) 566 panic("failed to create swap_zone."); 567 do { 568 if (uma_zone_reserve_kva(swap_zone, n)) 569 break; 570 /* 571 * if the allocation failed, try a zone two thirds the 572 * size of the previous attempt. 573 */ 574 n -= ((n + 2) / 3); 575 } while (n > 0); 576 if (n2 != n) 577 printf("Swap zone entries reduced from %lu to %lu.\n", n2, n); 578 swap_maxpages = n * SWAP_META_PAGES; 579 swzone = n * sizeof(struct swblock); 580 n2 = n; 581 582 /* 583 * Initialize our meta-data hash table. The swapper does not need to 584 * be quite as efficient as the VM system, so we do not use an 585 * oversized hash table. 586 * 587 * n: size of hash table, must be power of 2 588 * swhash_mask: hash table index mask 589 */ 590 for (n = 1; n < n2 / 8; n *= 2) 591 ; 592 swhash = malloc(sizeof(struct swblock *) * n, M_VMPGDATA, M_WAITOK | M_ZERO); 593 swhash_mask = n - 1; 594 mtx_init(&swhash_mtx, "swap_pager swhash", NULL, MTX_DEF); 595 } 596 597 /* 598 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 599 * its metadata structures. 600 * 601 * This routine is called from the mmap and fork code to create a new 602 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object 603 * and then converting it with swp_pager_meta_build(). 604 * 605 * This routine may block in vm_object_allocate() and create a named 606 * object lookup race, so we must interlock. 607 * 608 * MPSAFE 609 */ 610 static vm_object_t 611 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 612 vm_ooffset_t offset, struct ucred *cred) 613 { 614 vm_object_t object; 615 vm_pindex_t pindex; 616 617 pindex = OFF_TO_IDX(offset + PAGE_MASK + size); 618 if (handle) { 619 mtx_lock(&Giant); 620 /* 621 * Reference existing named region or allocate new one. There 622 * should not be a race here against swp_pager_meta_build() 623 * as called from vm_page_remove() in regards to the lookup 624 * of the handle. 625 */ 626 sx_xlock(&sw_alloc_sx); 627 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 628 if (object == NULL) { 629 if (cred != NULL) { 630 if (!swap_reserve_by_cred(size, cred)) { 631 sx_xunlock(&sw_alloc_sx); 632 mtx_unlock(&Giant); 633 return (NULL); 634 } 635 crhold(cred); 636 } 637 object = vm_object_allocate(OBJT_DEFAULT, pindex); 638 VM_OBJECT_WLOCK(object); 639 object->handle = handle; 640 if (cred != NULL) { 641 object->cred = cred; 642 object->charge = size; 643 } 644 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 645 VM_OBJECT_WUNLOCK(object); 646 } 647 sx_xunlock(&sw_alloc_sx); 648 mtx_unlock(&Giant); 649 } else { 650 if (cred != NULL) { 651 if (!swap_reserve_by_cred(size, cred)) 652 return (NULL); 653 crhold(cred); 654 } 655 object = vm_object_allocate(OBJT_DEFAULT, pindex); 656 VM_OBJECT_WLOCK(object); 657 if (cred != NULL) { 658 object->cred = cred; 659 object->charge = size; 660 } 661 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 662 VM_OBJECT_WUNLOCK(object); 663 } 664 return (object); 665 } 666 667 /* 668 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 669 * 670 * The swap backing for the object is destroyed. The code is 671 * designed such that we can reinstantiate it later, but this 672 * routine is typically called only when the entire object is 673 * about to be destroyed. 674 * 675 * The object must be locked. 676 */ 677 static void 678 swap_pager_dealloc(vm_object_t object) 679 { 680 681 /* 682 * Remove from list right away so lookups will fail if we block for 683 * pageout completion. 684 */ 685 if (object->handle != NULL) { 686 mtx_lock(&sw_alloc_mtx); 687 TAILQ_REMOVE(NOBJLIST(object->handle), object, pager_object_list); 688 mtx_unlock(&sw_alloc_mtx); 689 } 690 691 VM_OBJECT_ASSERT_WLOCKED(object); 692 vm_object_pip_wait(object, "swpdea"); 693 694 /* 695 * Free all remaining metadata. We only bother to free it from 696 * the swap meta data. We do not attempt to free swapblk's still 697 * associated with vm_page_t's for this object. We do not care 698 * if paging is still in progress on some objects. 699 */ 700 swp_pager_meta_free_all(object); 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 */ 721 static daddr_t 722 swp_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; 753 done: 754 mtx_unlock(&sw_dev_mtx); 755 return (blk); 756 } 757 758 static int 759 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 760 { 761 762 return (blk >= sp->sw_first && blk < sp->sw_end); 763 } 764 765 static void 766 swp_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 */ 800 static void 801 swp_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 */ 841 void 842 swap_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 */ 856 int 857 swap_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 */ 906 void 907 swap_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 */ 1011 static boolean_t 1012 swap_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 */ 1085 static void 1086 swap_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 */ 1111 static int 1112 swap_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_getpages_async(): 1266 * 1267 * Right now this is emulation of asynchronous operation on top of 1268 * swap_pager_getpages(). 1269 */ 1270 static int 1271 swap_pager_getpages_async(vm_object_t object, vm_page_t *m, int count, 1272 int reqpage, pgo_getpages_iodone_t iodone, void *arg) 1273 { 1274 int r, error; 1275 1276 r = swap_pager_getpages(object, m, count, reqpage); 1277 VM_OBJECT_WUNLOCK(object); 1278 switch (r) { 1279 case VM_PAGER_OK: 1280 error = 0; 1281 break; 1282 case VM_PAGER_ERROR: 1283 error = EIO; 1284 break; 1285 case VM_PAGER_FAIL: 1286 error = EINVAL; 1287 break; 1288 default: 1289 panic("unhandled swap_pager_getpages() error %d", r); 1290 } 1291 (iodone)(arg, m, count, error); 1292 VM_OBJECT_WLOCK(object); 1293 1294 return (r); 1295 } 1296 1297 /* 1298 * swap_pager_putpages: 1299 * 1300 * Assign swap (if necessary) and initiate I/O on the specified pages. 1301 * 1302 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1303 * are automatically converted to SWAP objects. 1304 * 1305 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1306 * vm_page reservation system coupled with properly written VFS devices 1307 * should ensure that no low-memory deadlock occurs. This is an area 1308 * which needs work. 1309 * 1310 * The parent has N vm_object_pip_add() references prior to 1311 * calling us and will remove references for rtvals[] that are 1312 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1313 * completion. 1314 * 1315 * The parent has soft-busy'd the pages it passes us and will unbusy 1316 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1317 * We need to unbusy the rest on I/O completion. 1318 */ 1319 void 1320 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1321 int flags, int *rtvals) 1322 { 1323 int i, n; 1324 boolean_t sync; 1325 1326 if (count && m[0]->object != object) { 1327 panic("swap_pager_putpages: object mismatch %p/%p", 1328 object, 1329 m[0]->object 1330 ); 1331 } 1332 1333 /* 1334 * Step 1 1335 * 1336 * Turn object into OBJT_SWAP 1337 * check for bogus sysops 1338 * force sync if not pageout process 1339 */ 1340 if (object->type != OBJT_SWAP) 1341 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1342 VM_OBJECT_WUNLOCK(object); 1343 1344 n = 0; 1345 if (curproc != pageproc) 1346 sync = TRUE; 1347 else 1348 sync = (flags & VM_PAGER_PUT_SYNC) != 0; 1349 1350 /* 1351 * Step 2 1352 * 1353 * Update nsw parameters from swap_async_max sysctl values. 1354 * Do not let the sysop crash the machine with bogus numbers. 1355 */ 1356 mtx_lock(&pbuf_mtx); 1357 if (swap_async_max != nsw_wcount_async_max) { 1358 int n; 1359 1360 /* 1361 * limit range 1362 */ 1363 if ((n = swap_async_max) > nswbuf / 2) 1364 n = nswbuf / 2; 1365 if (n < 1) 1366 n = 1; 1367 swap_async_max = n; 1368 1369 /* 1370 * Adjust difference ( if possible ). If the current async 1371 * count is too low, we may not be able to make the adjustment 1372 * at this time. 1373 */ 1374 n -= nsw_wcount_async_max; 1375 if (nsw_wcount_async + n >= 0) { 1376 nsw_wcount_async += n; 1377 nsw_wcount_async_max += n; 1378 wakeup(&nsw_wcount_async); 1379 } 1380 } 1381 mtx_unlock(&pbuf_mtx); 1382 1383 /* 1384 * Step 3 1385 * 1386 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1387 * The page is left dirty until the pageout operation completes 1388 * successfully. 1389 */ 1390 for (i = 0; i < count; i += n) { 1391 int j; 1392 struct buf *bp; 1393 daddr_t blk; 1394 1395 /* 1396 * Maximum I/O size is limited by a number of factors. 1397 */ 1398 n = min(BLIST_MAX_ALLOC, count - i); 1399 n = min(n, nsw_cluster_max); 1400 1401 /* 1402 * Get biggest block of swap we can. If we fail, fall 1403 * back and try to allocate a smaller block. Don't go 1404 * overboard trying to allocate space if it would overly 1405 * fragment swap. 1406 */ 1407 while ( 1408 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE && 1409 n > 4 1410 ) { 1411 n >>= 1; 1412 } 1413 if (blk == SWAPBLK_NONE) { 1414 for (j = 0; j < n; ++j) 1415 rtvals[i+j] = VM_PAGER_FAIL; 1416 continue; 1417 } 1418 1419 /* 1420 * All I/O parameters have been satisfied, build the I/O 1421 * request and assign the swap space. 1422 */ 1423 if (sync == TRUE) { 1424 bp = getpbuf(&nsw_wcount_sync); 1425 } else { 1426 bp = getpbuf(&nsw_wcount_async); 1427 bp->b_flags = B_ASYNC; 1428 } 1429 bp->b_flags |= B_PAGING; 1430 bp->b_iocmd = BIO_WRITE; 1431 1432 bp->b_rcred = crhold(thread0.td_ucred); 1433 bp->b_wcred = crhold(thread0.td_ucred); 1434 bp->b_bcount = PAGE_SIZE * n; 1435 bp->b_bufsize = PAGE_SIZE * n; 1436 bp->b_blkno = blk; 1437 1438 VM_OBJECT_WLOCK(object); 1439 for (j = 0; j < n; ++j) { 1440 vm_page_t mreq = m[i+j]; 1441 1442 swp_pager_meta_build( 1443 mreq->object, 1444 mreq->pindex, 1445 blk + j 1446 ); 1447 vm_page_dirty(mreq); 1448 rtvals[i+j] = VM_PAGER_OK; 1449 1450 mreq->oflags |= VPO_SWAPINPROG; 1451 bp->b_pages[j] = mreq; 1452 } 1453 VM_OBJECT_WUNLOCK(object); 1454 bp->b_npages = n; 1455 /* 1456 * Must set dirty range for NFS to work. 1457 */ 1458 bp->b_dirtyoff = 0; 1459 bp->b_dirtyend = bp->b_bcount; 1460 1461 PCPU_INC(cnt.v_swapout); 1462 PCPU_ADD(cnt.v_swappgsout, bp->b_npages); 1463 1464 /* 1465 * asynchronous 1466 * 1467 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1468 */ 1469 if (sync == FALSE) { 1470 bp->b_iodone = swp_pager_async_iodone; 1471 BUF_KERNPROC(bp); 1472 swp_pager_strategy(bp); 1473 1474 for (j = 0; j < n; ++j) 1475 rtvals[i+j] = VM_PAGER_PEND; 1476 /* restart outter loop */ 1477 continue; 1478 } 1479 1480 /* 1481 * synchronous 1482 * 1483 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1484 */ 1485 bp->b_iodone = bdone; 1486 swp_pager_strategy(bp); 1487 1488 /* 1489 * Wait for the sync I/O to complete, then update rtvals. 1490 * We just set the rtvals[] to VM_PAGER_PEND so we can call 1491 * our async completion routine at the end, thus avoiding a 1492 * double-free. 1493 */ 1494 bwait(bp, PVM, "swwrt"); 1495 for (j = 0; j < n; ++j) 1496 rtvals[i+j] = VM_PAGER_PEND; 1497 /* 1498 * Now that we are through with the bp, we can call the 1499 * normal async completion, which frees everything up. 1500 */ 1501 swp_pager_async_iodone(bp); 1502 } 1503 VM_OBJECT_WLOCK(object); 1504 } 1505 1506 /* 1507 * swp_pager_async_iodone: 1508 * 1509 * Completion routine for asynchronous reads and writes from/to swap. 1510 * Also called manually by synchronous code to finish up a bp. 1511 * 1512 * This routine may not sleep. 1513 */ 1514 static void 1515 swp_pager_async_iodone(struct buf *bp) 1516 { 1517 int i; 1518 vm_object_t object = NULL; 1519 1520 /* 1521 * report error 1522 */ 1523 if (bp->b_ioflags & BIO_ERROR) { 1524 printf( 1525 "swap_pager: I/O error - %s failed; blkno %ld," 1526 "size %ld, error %d\n", 1527 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1528 (long)bp->b_blkno, 1529 (long)bp->b_bcount, 1530 bp->b_error 1531 ); 1532 } 1533 1534 /* 1535 * remove the mapping for kernel virtual 1536 */ 1537 if ((bp->b_flags & B_UNMAPPED) != 0) { 1538 bp->b_data = bp->b_kvaalloc; 1539 bp->b_kvabase = bp->b_kvaalloc; 1540 bp->b_flags &= ~B_UNMAPPED; 1541 } else 1542 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1543 1544 if (bp->b_npages) { 1545 object = bp->b_pages[0]->object; 1546 VM_OBJECT_WLOCK(object); 1547 } 1548 1549 /* 1550 * cleanup pages. If an error occurs writing to swap, we are in 1551 * very serious trouble. If it happens to be a disk error, though, 1552 * we may be able to recover by reassigning the swap later on. So 1553 * in this case we remove the m->swapblk assignment for the page 1554 * but do not free it in the rlist. The errornous block(s) are thus 1555 * never reallocated as swap. Redirty the page and continue. 1556 */ 1557 for (i = 0; i < bp->b_npages; ++i) { 1558 vm_page_t m = bp->b_pages[i]; 1559 1560 m->oflags &= ~VPO_SWAPINPROG; 1561 if (m->oflags & VPO_SWAPSLEEP) { 1562 m->oflags &= ~VPO_SWAPSLEEP; 1563 wakeup(&object->paging_in_progress); 1564 } 1565 1566 if (bp->b_ioflags & BIO_ERROR) { 1567 /* 1568 * If an error occurs I'd love to throw the swapblk 1569 * away without freeing it back to swapspace, so it 1570 * can never be used again. But I can't from an 1571 * interrupt. 1572 */ 1573 if (bp->b_iocmd == BIO_READ) { 1574 /* 1575 * When reading, reqpage needs to stay 1576 * locked for the parent, but all other 1577 * pages can be freed. We still want to 1578 * wakeup the parent waiting on the page, 1579 * though. ( also: pg_reqpage can be -1 and 1580 * not match anything ). 1581 * 1582 * We have to wake specifically requested pages 1583 * up too because we cleared VPO_SWAPINPROG and 1584 * someone may be waiting for that. 1585 * 1586 * NOTE: for reads, m->dirty will probably 1587 * be overridden by the original caller of 1588 * getpages so don't play cute tricks here. 1589 */ 1590 m->valid = 0; 1591 if (i != bp->b_pager.pg_reqpage) 1592 swp_pager_free_nrpage(m); 1593 else { 1594 vm_page_lock(m); 1595 vm_page_flash(m); 1596 vm_page_unlock(m); 1597 } 1598 /* 1599 * If i == bp->b_pager.pg_reqpage, do not wake 1600 * the page up. The caller needs to. 1601 */ 1602 } else { 1603 /* 1604 * If a write error occurs, reactivate page 1605 * so it doesn't clog the inactive list, 1606 * then finish the I/O. 1607 */ 1608 vm_page_dirty(m); 1609 vm_page_lock(m); 1610 vm_page_activate(m); 1611 vm_page_unlock(m); 1612 vm_page_sunbusy(m); 1613 } 1614 } else if (bp->b_iocmd == BIO_READ) { 1615 /* 1616 * NOTE: for reads, m->dirty will probably be 1617 * overridden by the original caller of getpages so 1618 * we cannot set them in order to free the underlying 1619 * swap in a low-swap situation. I don't think we'd 1620 * want to do that anyway, but it was an optimization 1621 * that existed in the old swapper for a time before 1622 * it got ripped out due to precisely this problem. 1623 * 1624 * If not the requested page then deactivate it. 1625 * 1626 * Note that the requested page, reqpage, is left 1627 * busied, but we still have to wake it up. The 1628 * other pages are released (unbusied) by 1629 * vm_page_xunbusy(). 1630 */ 1631 KASSERT(!pmap_page_is_mapped(m), 1632 ("swp_pager_async_iodone: page %p is mapped", m)); 1633 m->valid = VM_PAGE_BITS_ALL; 1634 KASSERT(m->dirty == 0, 1635 ("swp_pager_async_iodone: page %p is dirty", m)); 1636 1637 /* 1638 * We have to wake specifically requested pages 1639 * up too because we cleared VPO_SWAPINPROG and 1640 * could be waiting for it in getpages. However, 1641 * be sure to not unbusy getpages specifically 1642 * requested page - getpages expects it to be 1643 * left busy. 1644 */ 1645 if (i != bp->b_pager.pg_reqpage) { 1646 vm_page_lock(m); 1647 vm_page_deactivate(m); 1648 vm_page_unlock(m); 1649 vm_page_xunbusy(m); 1650 } else { 1651 vm_page_lock(m); 1652 vm_page_flash(m); 1653 vm_page_unlock(m); 1654 } 1655 } else { 1656 /* 1657 * For write success, clear the dirty 1658 * status, then finish the I/O ( which decrements the 1659 * busy count and possibly wakes waiter's up ). 1660 */ 1661 KASSERT(!pmap_page_is_write_mapped(m), 1662 ("swp_pager_async_iodone: page %p is not write" 1663 " protected", m)); 1664 vm_page_undirty(m); 1665 vm_page_sunbusy(m); 1666 if (vm_page_count_severe()) { 1667 vm_page_lock(m); 1668 vm_page_try_to_cache(m); 1669 vm_page_unlock(m); 1670 } 1671 } 1672 } 1673 1674 /* 1675 * adjust pip. NOTE: the original parent may still have its own 1676 * pip refs on the object. 1677 */ 1678 if (object != NULL) { 1679 vm_object_pip_wakeupn(object, bp->b_npages); 1680 VM_OBJECT_WUNLOCK(object); 1681 } 1682 1683 /* 1684 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1685 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1686 * trigger a KASSERT in relpbuf(). 1687 */ 1688 if (bp->b_vp) { 1689 bp->b_vp = NULL; 1690 bp->b_bufobj = NULL; 1691 } 1692 /* 1693 * release the physical I/O buffer 1694 */ 1695 relpbuf( 1696 bp, 1697 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount : 1698 ((bp->b_flags & B_ASYNC) ? 1699 &nsw_wcount_async : 1700 &nsw_wcount_sync 1701 ) 1702 ) 1703 ); 1704 } 1705 1706 /* 1707 * swap_pager_isswapped: 1708 * 1709 * Return 1 if at least one page in the given object is paged 1710 * out to the given swap device. 1711 * 1712 * This routine may not sleep. 1713 */ 1714 int 1715 swap_pager_isswapped(vm_object_t object, struct swdevt *sp) 1716 { 1717 daddr_t index = 0; 1718 int bcount; 1719 int i; 1720 1721 VM_OBJECT_ASSERT_WLOCKED(object); 1722 if (object->type != OBJT_SWAP) 1723 return (0); 1724 1725 mtx_lock(&swhash_mtx); 1726 for (bcount = 0; bcount < object->un_pager.swp.swp_bcount; bcount++) { 1727 struct swblock *swap; 1728 1729 if ((swap = *swp_pager_hash(object, index)) != NULL) { 1730 for (i = 0; i < SWAP_META_PAGES; ++i) { 1731 if (swp_pager_isondev(swap->swb_pages[i], sp)) { 1732 mtx_unlock(&swhash_mtx); 1733 return (1); 1734 } 1735 } 1736 } 1737 index += SWAP_META_PAGES; 1738 } 1739 mtx_unlock(&swhash_mtx); 1740 return (0); 1741 } 1742 1743 /* 1744 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in 1745 * 1746 * This routine dissociates the page at the given index within a 1747 * swap block from its backing store, paging it in if necessary. 1748 * If the page is paged in, it is placed in the inactive queue, 1749 * since it had its backing store ripped out from under it. 1750 * We also attempt to swap in all other pages in the swap block, 1751 * we only guarantee that the one at the specified index is 1752 * paged in. 1753 * 1754 * XXX - The code to page the whole block in doesn't work, so we 1755 * revert to the one-by-one behavior for now. Sigh. 1756 */ 1757 static inline void 1758 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex) 1759 { 1760 vm_page_t m; 1761 1762 vm_object_pip_add(object, 1); 1763 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL); 1764 if (m->valid == VM_PAGE_BITS_ALL) { 1765 vm_object_pip_wakeup(object); 1766 vm_page_dirty(m); 1767 vm_page_lock(m); 1768 vm_page_activate(m); 1769 vm_page_unlock(m); 1770 vm_page_xunbusy(m); 1771 vm_pager_page_unswapped(m); 1772 return; 1773 } 1774 1775 if (swap_pager_getpages(object, &m, 1, 0) != VM_PAGER_OK) 1776 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/ 1777 vm_object_pip_wakeup(object); 1778 vm_page_dirty(m); 1779 vm_page_lock(m); 1780 vm_page_deactivate(m); 1781 vm_page_unlock(m); 1782 vm_page_xunbusy(m); 1783 vm_pager_page_unswapped(m); 1784 } 1785 1786 /* 1787 * swap_pager_swapoff: 1788 * 1789 * Page in all of the pages that have been paged out to the 1790 * given device. The corresponding blocks in the bitmap must be 1791 * marked as allocated and the device must be flagged SW_CLOSING. 1792 * There may be no processes swapped out to the device. 1793 * 1794 * This routine may block. 1795 */ 1796 static void 1797 swap_pager_swapoff(struct swdevt *sp) 1798 { 1799 struct swblock *swap; 1800 int i, j, retries; 1801 1802 GIANT_REQUIRED; 1803 1804 retries = 0; 1805 full_rescan: 1806 mtx_lock(&swhash_mtx); 1807 for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */ 1808 restart: 1809 for (swap = swhash[i]; swap != NULL; swap = swap->swb_hnext) { 1810 vm_object_t object = swap->swb_object; 1811 vm_pindex_t pindex = swap->swb_index; 1812 for (j = 0; j < SWAP_META_PAGES; ++j) { 1813 if (swp_pager_isondev(swap->swb_pages[j], sp)) { 1814 /* avoid deadlock */ 1815 if (!VM_OBJECT_TRYWLOCK(object)) { 1816 break; 1817 } else { 1818 mtx_unlock(&swhash_mtx); 1819 swp_pager_force_pagein(object, 1820 pindex + j); 1821 VM_OBJECT_WUNLOCK(object); 1822 mtx_lock(&swhash_mtx); 1823 goto restart; 1824 } 1825 } 1826 } 1827 } 1828 } 1829 mtx_unlock(&swhash_mtx); 1830 if (sp->sw_used) { 1831 /* 1832 * Objects may be locked or paging to the device being 1833 * removed, so we will miss their pages and need to 1834 * make another pass. We have marked this device as 1835 * SW_CLOSING, so the activity should finish soon. 1836 */ 1837 retries++; 1838 if (retries > 100) { 1839 panic("swapoff: failed to locate %d swap blocks", 1840 sp->sw_used); 1841 } 1842 pause("swpoff", hz / 20); 1843 goto full_rescan; 1844 } 1845 } 1846 1847 /************************************************************************ 1848 * SWAP META DATA * 1849 ************************************************************************ 1850 * 1851 * These routines manipulate the swap metadata stored in the 1852 * OBJT_SWAP object. 1853 * 1854 * Swap metadata is implemented with a global hash and not directly 1855 * linked into the object. Instead the object simply contains 1856 * appropriate tracking counters. 1857 */ 1858 1859 /* 1860 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1861 * 1862 * We first convert the object to a swap object if it is a default 1863 * object. 1864 * 1865 * The specified swapblk is added to the object's swap metadata. If 1866 * the swapblk is not valid, it is freed instead. Any previously 1867 * assigned swapblk is freed. 1868 */ 1869 static void 1870 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1871 { 1872 static volatile int exhausted; 1873 struct swblock *swap; 1874 struct swblock **pswap; 1875 int idx; 1876 1877 VM_OBJECT_ASSERT_WLOCKED(object); 1878 /* 1879 * Convert default object to swap object if necessary 1880 */ 1881 if (object->type != OBJT_SWAP) { 1882 object->type = OBJT_SWAP; 1883 object->un_pager.swp.swp_bcount = 0; 1884 1885 if (object->handle != NULL) { 1886 mtx_lock(&sw_alloc_mtx); 1887 TAILQ_INSERT_TAIL( 1888 NOBJLIST(object->handle), 1889 object, 1890 pager_object_list 1891 ); 1892 mtx_unlock(&sw_alloc_mtx); 1893 } 1894 } 1895 1896 /* 1897 * Locate hash entry. If not found create, but if we aren't adding 1898 * anything just return. If we run out of space in the map we wait 1899 * and, since the hash table may have changed, retry. 1900 */ 1901 retry: 1902 mtx_lock(&swhash_mtx); 1903 pswap = swp_pager_hash(object, pindex); 1904 1905 if ((swap = *pswap) == NULL) { 1906 int i; 1907 1908 if (swapblk == SWAPBLK_NONE) 1909 goto done; 1910 1911 swap = *pswap = uma_zalloc(swap_zone, M_NOWAIT | 1912 (curproc == pageproc ? M_USE_RESERVE : 0)); 1913 if (swap == NULL) { 1914 mtx_unlock(&swhash_mtx); 1915 VM_OBJECT_WUNLOCK(object); 1916 if (uma_zone_exhausted(swap_zone)) { 1917 if (atomic_cmpset_int(&exhausted, 0, 1)) 1918 printf("swap zone exhausted, " 1919 "increase kern.maxswzone\n"); 1920 vm_pageout_oom(VM_OOM_SWAPZ); 1921 pause("swzonex", 10); 1922 } else 1923 VM_WAIT; 1924 VM_OBJECT_WLOCK(object); 1925 goto retry; 1926 } 1927 1928 if (atomic_cmpset_int(&exhausted, 1, 0)) 1929 printf("swap zone ok\n"); 1930 1931 swap->swb_hnext = NULL; 1932 swap->swb_object = object; 1933 swap->swb_index = pindex & ~(vm_pindex_t)SWAP_META_MASK; 1934 swap->swb_count = 0; 1935 1936 ++object->un_pager.swp.swp_bcount; 1937 1938 for (i = 0; i < SWAP_META_PAGES; ++i) 1939 swap->swb_pages[i] = SWAPBLK_NONE; 1940 } 1941 1942 /* 1943 * Delete prior contents of metadata 1944 */ 1945 idx = pindex & SWAP_META_MASK; 1946 1947 if (swap->swb_pages[idx] != SWAPBLK_NONE) { 1948 swp_pager_freeswapspace(swap->swb_pages[idx], 1); 1949 --swap->swb_count; 1950 } 1951 1952 /* 1953 * Enter block into metadata 1954 */ 1955 swap->swb_pages[idx] = swapblk; 1956 if (swapblk != SWAPBLK_NONE) 1957 ++swap->swb_count; 1958 done: 1959 mtx_unlock(&swhash_mtx); 1960 } 1961 1962 /* 1963 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 1964 * 1965 * The requested range of blocks is freed, with any associated swap 1966 * returned to the swap bitmap. 1967 * 1968 * This routine will free swap metadata structures as they are cleaned 1969 * out. This routine does *NOT* operate on swap metadata associated 1970 * with resident pages. 1971 */ 1972 static void 1973 swp_pager_meta_free(vm_object_t object, vm_pindex_t index, daddr_t count) 1974 { 1975 1976 VM_OBJECT_ASSERT_LOCKED(object); 1977 if (object->type != OBJT_SWAP) 1978 return; 1979 1980 while (count > 0) { 1981 struct swblock **pswap; 1982 struct swblock *swap; 1983 1984 mtx_lock(&swhash_mtx); 1985 pswap = swp_pager_hash(object, index); 1986 1987 if ((swap = *pswap) != NULL) { 1988 daddr_t v = swap->swb_pages[index & SWAP_META_MASK]; 1989 1990 if (v != SWAPBLK_NONE) { 1991 swp_pager_freeswapspace(v, 1); 1992 swap->swb_pages[index & SWAP_META_MASK] = 1993 SWAPBLK_NONE; 1994 if (--swap->swb_count == 0) { 1995 *pswap = swap->swb_hnext; 1996 uma_zfree(swap_zone, swap); 1997 --object->un_pager.swp.swp_bcount; 1998 } 1999 } 2000 --count; 2001 ++index; 2002 } else { 2003 int n = SWAP_META_PAGES - (index & SWAP_META_MASK); 2004 count -= n; 2005 index += n; 2006 } 2007 mtx_unlock(&swhash_mtx); 2008 } 2009 } 2010 2011 /* 2012 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 2013 * 2014 * This routine locates and destroys all swap metadata associated with 2015 * an object. 2016 */ 2017 static void 2018 swp_pager_meta_free_all(vm_object_t object) 2019 { 2020 daddr_t index = 0; 2021 2022 VM_OBJECT_ASSERT_WLOCKED(object); 2023 if (object->type != OBJT_SWAP) 2024 return; 2025 2026 while (object->un_pager.swp.swp_bcount) { 2027 struct swblock **pswap; 2028 struct swblock *swap; 2029 2030 mtx_lock(&swhash_mtx); 2031 pswap = swp_pager_hash(object, index); 2032 if ((swap = *pswap) != NULL) { 2033 int i; 2034 2035 for (i = 0; i < SWAP_META_PAGES; ++i) { 2036 daddr_t v = swap->swb_pages[i]; 2037 if (v != SWAPBLK_NONE) { 2038 --swap->swb_count; 2039 swp_pager_freeswapspace(v, 1); 2040 } 2041 } 2042 if (swap->swb_count != 0) 2043 panic("swap_pager_meta_free_all: swb_count != 0"); 2044 *pswap = swap->swb_hnext; 2045 uma_zfree(swap_zone, swap); 2046 --object->un_pager.swp.swp_bcount; 2047 } 2048 mtx_unlock(&swhash_mtx); 2049 index += SWAP_META_PAGES; 2050 } 2051 } 2052 2053 /* 2054 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. 2055 * 2056 * This routine is capable of looking up, popping, or freeing 2057 * swapblk assignments in the swap meta data or in the vm_page_t. 2058 * The routine typically returns the swapblk being looked-up, or popped, 2059 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block 2060 * was invalid. This routine will automatically free any invalid 2061 * meta-data swapblks. 2062 * 2063 * It is not possible to store invalid swapblks in the swap meta data 2064 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking. 2065 * 2066 * When acting on a busy resident page and paging is in progress, we 2067 * have to wait until paging is complete but otherwise can act on the 2068 * busy page. 2069 * 2070 * SWM_FREE remove and free swap block from metadata 2071 * SWM_POP remove from meta data but do not free.. pop it out 2072 */ 2073 static daddr_t 2074 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags) 2075 { 2076 struct swblock **pswap; 2077 struct swblock *swap; 2078 daddr_t r1; 2079 int idx; 2080 2081 VM_OBJECT_ASSERT_LOCKED(object); 2082 /* 2083 * The meta data only exists of the object is OBJT_SWAP 2084 * and even then might not be allocated yet. 2085 */ 2086 if (object->type != OBJT_SWAP) 2087 return (SWAPBLK_NONE); 2088 2089 r1 = SWAPBLK_NONE; 2090 mtx_lock(&swhash_mtx); 2091 pswap = swp_pager_hash(object, pindex); 2092 2093 if ((swap = *pswap) != NULL) { 2094 idx = pindex & SWAP_META_MASK; 2095 r1 = swap->swb_pages[idx]; 2096 2097 if (r1 != SWAPBLK_NONE) { 2098 if (flags & SWM_FREE) { 2099 swp_pager_freeswapspace(r1, 1); 2100 r1 = SWAPBLK_NONE; 2101 } 2102 if (flags & (SWM_FREE|SWM_POP)) { 2103 swap->swb_pages[idx] = SWAPBLK_NONE; 2104 if (--swap->swb_count == 0) { 2105 *pswap = swap->swb_hnext; 2106 uma_zfree(swap_zone, swap); 2107 --object->un_pager.swp.swp_bcount; 2108 } 2109 } 2110 } 2111 } 2112 mtx_unlock(&swhash_mtx); 2113 return (r1); 2114 } 2115 2116 /* 2117 * System call swapon(name) enables swapping on device name, 2118 * which must be in the swdevsw. Return EBUSY 2119 * if already swapping on this device. 2120 */ 2121 #ifndef _SYS_SYSPROTO_H_ 2122 struct swapon_args { 2123 char *name; 2124 }; 2125 #endif 2126 2127 /* 2128 * MPSAFE 2129 */ 2130 /* ARGSUSED */ 2131 int 2132 sys_swapon(struct thread *td, struct swapon_args *uap) 2133 { 2134 struct vattr attr; 2135 struct vnode *vp; 2136 struct nameidata nd; 2137 int error; 2138 2139 error = priv_check(td, PRIV_SWAPON); 2140 if (error) 2141 return (error); 2142 2143 mtx_lock(&Giant); 2144 while (swdev_syscall_active) 2145 tsleep(&swdev_syscall_active, PUSER - 1, "swpon", 0); 2146 swdev_syscall_active = 1; 2147 2148 /* 2149 * Swap metadata may not fit in the KVM if we have physical 2150 * memory of >1GB. 2151 */ 2152 if (swap_zone == NULL) { 2153 error = ENOMEM; 2154 goto done; 2155 } 2156 2157 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2158 uap->name, td); 2159 error = namei(&nd); 2160 if (error) 2161 goto done; 2162 2163 NDFREE(&nd, NDF_ONLY_PNBUF); 2164 vp = nd.ni_vp; 2165 2166 if (vn_isdisk(vp, &error)) { 2167 error = swapongeom(td, vp); 2168 } else if (vp->v_type == VREG && 2169 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2170 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2171 /* 2172 * Allow direct swapping to NFS regular files in the same 2173 * way that nfs_mountroot() sets up diskless swapping. 2174 */ 2175 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2176 } 2177 2178 if (error) 2179 vrele(vp); 2180 done: 2181 swdev_syscall_active = 0; 2182 wakeup_one(&swdev_syscall_active); 2183 mtx_unlock(&Giant); 2184 return (error); 2185 } 2186 2187 /* 2188 * Check that the total amount of swap currently configured does not 2189 * exceed half the theoretical maximum. If it does, print a warning 2190 * message and return -1; otherwise, return 0. 2191 */ 2192 static int 2193 swapon_check_swzone(unsigned long npages) 2194 { 2195 unsigned long maxpages; 2196 2197 /* absolute maximum we can handle assuming 100% efficiency */ 2198 maxpages = uma_zone_get_max(swap_zone) * SWAP_META_PAGES; 2199 2200 /* recommend using no more than half that amount */ 2201 if (npages > maxpages / 2) { 2202 printf("warning: total configured swap (%lu pages) " 2203 "exceeds maximum recommended amount (%lu pages).\n", 2204 npages, maxpages / 2); 2205 printf("warning: increase kern.maxswzone " 2206 "or reduce amount of swap.\n"); 2207 return (-1); 2208 } 2209 return (0); 2210 } 2211 2212 static void 2213 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2214 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2215 { 2216 struct swdevt *sp, *tsp; 2217 swblk_t dvbase; 2218 u_long mblocks; 2219 2220 /* 2221 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2222 * First chop nblks off to page-align it, then convert. 2223 * 2224 * sw->sw_nblks is in page-sized chunks now too. 2225 */ 2226 nblks &= ~(ctodb(1) - 1); 2227 nblks = dbtoc(nblks); 2228 2229 /* 2230 * If we go beyond this, we get overflows in the radix 2231 * tree bitmap code. 2232 */ 2233 mblocks = 0x40000000 / BLIST_META_RADIX; 2234 if (nblks > mblocks) { 2235 printf( 2236 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2237 mblocks / 1024 / 1024 * PAGE_SIZE); 2238 nblks = mblocks; 2239 } 2240 2241 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2242 sp->sw_vp = vp; 2243 sp->sw_id = id; 2244 sp->sw_dev = dev; 2245 sp->sw_flags = 0; 2246 sp->sw_nblks = nblks; 2247 sp->sw_used = 0; 2248 sp->sw_strategy = strategy; 2249 sp->sw_close = close; 2250 sp->sw_flags = flags; 2251 2252 sp->sw_blist = blist_create(nblks, M_WAITOK); 2253 /* 2254 * Do not free the first two block in order to avoid overwriting 2255 * any bsd label at the front of the partition 2256 */ 2257 blist_free(sp->sw_blist, 2, nblks - 2); 2258 2259 dvbase = 0; 2260 mtx_lock(&sw_dev_mtx); 2261 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2262 if (tsp->sw_end >= dvbase) { 2263 /* 2264 * We put one uncovered page between the devices 2265 * in order to definitively prevent any cross-device 2266 * I/O requests 2267 */ 2268 dvbase = tsp->sw_end + 1; 2269 } 2270 } 2271 sp->sw_first = dvbase; 2272 sp->sw_end = dvbase + nblks; 2273 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2274 nswapdev++; 2275 swap_pager_avail += nblks; 2276 swap_total += (vm_ooffset_t)nblks * PAGE_SIZE; 2277 swapon_check_swzone(swap_total / PAGE_SIZE); 2278 swp_sizecheck(); 2279 mtx_unlock(&sw_dev_mtx); 2280 } 2281 2282 /* 2283 * SYSCALL: swapoff(devname) 2284 * 2285 * Disable swapping on the given device. 2286 * 2287 * XXX: Badly designed system call: it should use a device index 2288 * rather than filename as specification. We keep sw_vp around 2289 * only to make this work. 2290 */ 2291 #ifndef _SYS_SYSPROTO_H_ 2292 struct swapoff_args { 2293 char *name; 2294 }; 2295 #endif 2296 2297 /* 2298 * MPSAFE 2299 */ 2300 /* ARGSUSED */ 2301 int 2302 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2303 { 2304 struct vnode *vp; 2305 struct nameidata nd; 2306 struct swdevt *sp; 2307 int error; 2308 2309 error = priv_check(td, PRIV_SWAPOFF); 2310 if (error) 2311 return (error); 2312 2313 mtx_lock(&Giant); 2314 while (swdev_syscall_active) 2315 tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0); 2316 swdev_syscall_active = 1; 2317 2318 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2319 td); 2320 error = namei(&nd); 2321 if (error) 2322 goto done; 2323 NDFREE(&nd, NDF_ONLY_PNBUF); 2324 vp = nd.ni_vp; 2325 2326 mtx_lock(&sw_dev_mtx); 2327 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2328 if (sp->sw_vp == vp) 2329 break; 2330 } 2331 mtx_unlock(&sw_dev_mtx); 2332 if (sp == NULL) { 2333 error = EINVAL; 2334 goto done; 2335 } 2336 error = swapoff_one(sp, td->td_ucred); 2337 done: 2338 swdev_syscall_active = 0; 2339 wakeup_one(&swdev_syscall_active); 2340 mtx_unlock(&Giant); 2341 return (error); 2342 } 2343 2344 static int 2345 swapoff_one(struct swdevt *sp, struct ucred *cred) 2346 { 2347 u_long nblks, dvbase; 2348 #ifdef MAC 2349 int error; 2350 #endif 2351 2352 mtx_assert(&Giant, MA_OWNED); 2353 #ifdef MAC 2354 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2355 error = mac_system_check_swapoff(cred, sp->sw_vp); 2356 (void) VOP_UNLOCK(sp->sw_vp, 0); 2357 if (error != 0) 2358 return (error); 2359 #endif 2360 nblks = sp->sw_nblks; 2361 2362 /* 2363 * We can turn off this swap device safely only if the 2364 * available virtual memory in the system will fit the amount 2365 * of data we will have to page back in, plus an epsilon so 2366 * the system doesn't become critically low on swap space. 2367 */ 2368 if (vm_cnt.v_free_count + vm_cnt.v_cache_count + swap_pager_avail < 2369 nblks + nswap_lowat) { 2370 return (ENOMEM); 2371 } 2372 2373 /* 2374 * Prevent further allocations on this device. 2375 */ 2376 mtx_lock(&sw_dev_mtx); 2377 sp->sw_flags |= SW_CLOSING; 2378 for (dvbase = 0; dvbase < sp->sw_end; dvbase += dmmax) { 2379 swap_pager_avail -= blist_fill(sp->sw_blist, 2380 dvbase, dmmax); 2381 } 2382 swap_total -= (vm_ooffset_t)nblks * PAGE_SIZE; 2383 mtx_unlock(&sw_dev_mtx); 2384 2385 /* 2386 * Page in the contents of the device and close it. 2387 */ 2388 swap_pager_swapoff(sp); 2389 2390 sp->sw_close(curthread, sp); 2391 sp->sw_id = NULL; 2392 mtx_lock(&sw_dev_mtx); 2393 TAILQ_REMOVE(&swtailq, sp, sw_list); 2394 nswapdev--; 2395 if (nswapdev == 0) { 2396 swap_pager_full = 2; 2397 swap_pager_almost_full = 1; 2398 } 2399 if (swdevhd == sp) 2400 swdevhd = NULL; 2401 mtx_unlock(&sw_dev_mtx); 2402 blist_destroy(sp->sw_blist); 2403 free(sp, M_VMPGDATA); 2404 return (0); 2405 } 2406 2407 void 2408 swapoff_all(void) 2409 { 2410 struct swdevt *sp, *spt; 2411 const char *devname; 2412 int error; 2413 2414 mtx_lock(&Giant); 2415 while (swdev_syscall_active) 2416 tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0); 2417 swdev_syscall_active = 1; 2418 2419 mtx_lock(&sw_dev_mtx); 2420 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2421 mtx_unlock(&sw_dev_mtx); 2422 if (vn_isdisk(sp->sw_vp, NULL)) 2423 devname = devtoname(sp->sw_vp->v_rdev); 2424 else 2425 devname = "[file]"; 2426 error = swapoff_one(sp, thread0.td_ucred); 2427 if (error != 0) { 2428 printf("Cannot remove swap device %s (error=%d), " 2429 "skipping.\n", devname, error); 2430 } else if (bootverbose) { 2431 printf("Swap device %s removed.\n", devname); 2432 } 2433 mtx_lock(&sw_dev_mtx); 2434 } 2435 mtx_unlock(&sw_dev_mtx); 2436 2437 swdev_syscall_active = 0; 2438 wakeup_one(&swdev_syscall_active); 2439 mtx_unlock(&Giant); 2440 } 2441 2442 void 2443 swap_pager_status(int *total, int *used) 2444 { 2445 struct swdevt *sp; 2446 2447 *total = 0; 2448 *used = 0; 2449 mtx_lock(&sw_dev_mtx); 2450 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2451 *total += sp->sw_nblks; 2452 *used += sp->sw_used; 2453 } 2454 mtx_unlock(&sw_dev_mtx); 2455 } 2456 2457 int 2458 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2459 { 2460 struct swdevt *sp; 2461 const char *tmp_devname; 2462 int error, n; 2463 2464 n = 0; 2465 error = ENOENT; 2466 mtx_lock(&sw_dev_mtx); 2467 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2468 if (n != name) { 2469 n++; 2470 continue; 2471 } 2472 xs->xsw_version = XSWDEV_VERSION; 2473 xs->xsw_dev = sp->sw_dev; 2474 xs->xsw_flags = sp->sw_flags; 2475 xs->xsw_nblks = sp->sw_nblks; 2476 xs->xsw_used = sp->sw_used; 2477 if (devname != NULL) { 2478 if (vn_isdisk(sp->sw_vp, NULL)) 2479 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2480 else 2481 tmp_devname = "[file]"; 2482 strncpy(devname, tmp_devname, len); 2483 } 2484 error = 0; 2485 break; 2486 } 2487 mtx_unlock(&sw_dev_mtx); 2488 return (error); 2489 } 2490 2491 static int 2492 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2493 { 2494 struct xswdev xs; 2495 int error; 2496 2497 if (arg2 != 1) /* name length */ 2498 return (EINVAL); 2499 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2500 if (error != 0) 2501 return (error); 2502 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2503 return (error); 2504 } 2505 2506 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2507 "Number of swap devices"); 2508 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD, sysctl_vm_swap_info, 2509 "Swap statistics by device"); 2510 2511 /* 2512 * vmspace_swap_count() - count the approximate swap usage in pages for a 2513 * vmspace. 2514 * 2515 * The map must be locked. 2516 * 2517 * Swap usage is determined by taking the proportional swap used by 2518 * VM objects backing the VM map. To make up for fractional losses, 2519 * if the VM object has any swap use at all the associated map entries 2520 * count for at least 1 swap page. 2521 */ 2522 long 2523 vmspace_swap_count(struct vmspace *vmspace) 2524 { 2525 vm_map_t map; 2526 vm_map_entry_t cur; 2527 vm_object_t object; 2528 long count, n; 2529 2530 map = &vmspace->vm_map; 2531 count = 0; 2532 2533 for (cur = map->header.next; cur != &map->header; cur = cur->next) { 2534 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 && 2535 (object = cur->object.vm_object) != NULL) { 2536 VM_OBJECT_WLOCK(object); 2537 if (object->type == OBJT_SWAP && 2538 object->un_pager.swp.swp_bcount != 0) { 2539 n = (cur->end - cur->start) / PAGE_SIZE; 2540 count += object->un_pager.swp.swp_bcount * 2541 SWAP_META_PAGES * n / object->size + 1; 2542 } 2543 VM_OBJECT_WUNLOCK(object); 2544 } 2545 } 2546 return (count); 2547 } 2548 2549 /* 2550 * GEOM backend 2551 * 2552 * Swapping onto disk devices. 2553 * 2554 */ 2555 2556 static g_orphan_t swapgeom_orphan; 2557 2558 static struct g_class g_swap_class = { 2559 .name = "SWAP", 2560 .version = G_VERSION, 2561 .orphan = swapgeom_orphan, 2562 }; 2563 2564 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2565 2566 2567 static void 2568 swapgeom_close_ev(void *arg, int flags) 2569 { 2570 struct g_consumer *cp; 2571 2572 cp = arg; 2573 g_access(cp, -1, -1, 0); 2574 g_detach(cp); 2575 g_destroy_consumer(cp); 2576 } 2577 2578 static void 2579 swapgeom_done(struct bio *bp2) 2580 { 2581 struct swdevt *sp; 2582 struct buf *bp; 2583 struct g_consumer *cp; 2584 2585 bp = bp2->bio_caller2; 2586 cp = bp2->bio_from; 2587 bp->b_ioflags = bp2->bio_flags; 2588 if (bp2->bio_error) 2589 bp->b_ioflags |= BIO_ERROR; 2590 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2591 bp->b_error = bp2->bio_error; 2592 bufdone(bp); 2593 mtx_lock(&sw_dev_mtx); 2594 if ((--cp->index) == 0 && cp->private) { 2595 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) { 2596 sp = bp2->bio_caller1; 2597 sp->sw_id = NULL; 2598 } 2599 } 2600 mtx_unlock(&sw_dev_mtx); 2601 g_destroy_bio(bp2); 2602 } 2603 2604 static void 2605 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2606 { 2607 struct bio *bio; 2608 struct g_consumer *cp; 2609 2610 mtx_lock(&sw_dev_mtx); 2611 cp = sp->sw_id; 2612 if (cp == NULL) { 2613 mtx_unlock(&sw_dev_mtx); 2614 bp->b_error = ENXIO; 2615 bp->b_ioflags |= BIO_ERROR; 2616 bufdone(bp); 2617 return; 2618 } 2619 cp->index++; 2620 mtx_unlock(&sw_dev_mtx); 2621 if (bp->b_iocmd == BIO_WRITE) 2622 bio = g_new_bio(); 2623 else 2624 bio = g_alloc_bio(); 2625 if (bio == NULL) { 2626 bp->b_error = ENOMEM; 2627 bp->b_ioflags |= BIO_ERROR; 2628 bufdone(bp); 2629 return; 2630 } 2631 2632 bio->bio_caller1 = sp; 2633 bio->bio_caller2 = bp; 2634 bio->bio_cmd = bp->b_iocmd; 2635 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2636 bio->bio_length = bp->b_bcount; 2637 bio->bio_done = swapgeom_done; 2638 if ((bp->b_flags & B_UNMAPPED) != 0) { 2639 bio->bio_ma = bp->b_pages; 2640 bio->bio_data = unmapped_buf; 2641 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2642 bio->bio_ma_n = bp->b_npages; 2643 bio->bio_flags |= BIO_UNMAPPED; 2644 } else { 2645 bio->bio_data = bp->b_data; 2646 bio->bio_ma = NULL; 2647 } 2648 g_io_request(bio, cp); 2649 return; 2650 } 2651 2652 static void 2653 swapgeom_orphan(struct g_consumer *cp) 2654 { 2655 struct swdevt *sp; 2656 int destroy; 2657 2658 mtx_lock(&sw_dev_mtx); 2659 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2660 if (sp->sw_id == cp) { 2661 sp->sw_flags |= SW_CLOSING; 2662 break; 2663 } 2664 } 2665 cp->private = (void *)(uintptr_t)1; 2666 destroy = ((sp != NULL) && (cp->index == 0)); 2667 if (destroy) 2668 sp->sw_id = NULL; 2669 mtx_unlock(&sw_dev_mtx); 2670 if (destroy) 2671 swapgeom_close_ev(cp, 0); 2672 } 2673 2674 static void 2675 swapgeom_close(struct thread *td, struct swdevt *sw) 2676 { 2677 struct g_consumer *cp; 2678 2679 mtx_lock(&sw_dev_mtx); 2680 cp = sw->sw_id; 2681 sw->sw_id = NULL; 2682 mtx_unlock(&sw_dev_mtx); 2683 /* XXX: direct call when Giant untangled */ 2684 if (cp != NULL) 2685 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2686 } 2687 2688 2689 struct swh0h0 { 2690 struct cdev *dev; 2691 struct vnode *vp; 2692 int error; 2693 }; 2694 2695 static void 2696 swapongeom_ev(void *arg, int flags) 2697 { 2698 struct swh0h0 *swh; 2699 struct g_provider *pp; 2700 struct g_consumer *cp; 2701 static struct g_geom *gp; 2702 struct swdevt *sp; 2703 u_long nblks; 2704 int error; 2705 2706 swh = arg; 2707 swh->error = 0; 2708 pp = g_dev_getprovider(swh->dev); 2709 if (pp == NULL) { 2710 swh->error = ENODEV; 2711 return; 2712 } 2713 mtx_lock(&sw_dev_mtx); 2714 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2715 cp = sp->sw_id; 2716 if (cp != NULL && cp->provider == pp) { 2717 mtx_unlock(&sw_dev_mtx); 2718 swh->error = EBUSY; 2719 return; 2720 } 2721 } 2722 mtx_unlock(&sw_dev_mtx); 2723 if (gp == NULL) 2724 gp = g_new_geomf(&g_swap_class, "swap"); 2725 cp = g_new_consumer(gp); 2726 cp->index = 0; /* Number of active I/Os. */ 2727 cp->private = NULL; /* Orphanization flag */ 2728 g_attach(cp, pp); 2729 /* 2730 * XXX: Everytime you think you can improve the margin for 2731 * footshooting, somebody depends on the ability to do so: 2732 * savecore(8) wants to write to our swapdev so we cannot 2733 * set an exclusive count :-( 2734 */ 2735 error = g_access(cp, 1, 1, 0); 2736 if (error) { 2737 g_detach(cp); 2738 g_destroy_consumer(cp); 2739 swh->error = error; 2740 return; 2741 } 2742 nblks = pp->mediasize / DEV_BSIZE; 2743 swaponsomething(swh->vp, cp, nblks, swapgeom_strategy, 2744 swapgeom_close, dev2udev(swh->dev), 2745 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2746 swh->error = 0; 2747 } 2748 2749 static int 2750 swapongeom(struct thread *td, struct vnode *vp) 2751 { 2752 int error; 2753 struct swh0h0 swh; 2754 2755 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2756 2757 swh.dev = vp->v_rdev; 2758 swh.vp = vp; 2759 swh.error = 0; 2760 /* XXX: direct call when Giant untangled */ 2761 error = g_waitfor_event(swapongeom_ev, &swh, M_WAITOK, NULL); 2762 if (!error) 2763 error = swh.error; 2764 VOP_UNLOCK(vp, 0); 2765 return (error); 2766 } 2767 2768 /* 2769 * VNODE backend 2770 * 2771 * This is used mainly for network filesystem (read: probably only tested 2772 * with NFS) swapfiles. 2773 * 2774 */ 2775 2776 static void 2777 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2778 { 2779 struct vnode *vp2; 2780 2781 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2782 2783 vp2 = sp->sw_id; 2784 vhold(vp2); 2785 if (bp->b_iocmd == BIO_WRITE) { 2786 if (bp->b_bufobj) 2787 bufobj_wdrop(bp->b_bufobj); 2788 bufobj_wref(&vp2->v_bufobj); 2789 } 2790 if (bp->b_bufobj != &vp2->v_bufobj) 2791 bp->b_bufobj = &vp2->v_bufobj; 2792 bp->b_vp = vp2; 2793 bp->b_iooffset = dbtob(bp->b_blkno); 2794 bstrategy(bp); 2795 return; 2796 } 2797 2798 static void 2799 swapdev_close(struct thread *td, struct swdevt *sp) 2800 { 2801 2802 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2803 vrele(sp->sw_vp); 2804 } 2805 2806 2807 static int 2808 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2809 { 2810 struct swdevt *sp; 2811 int error; 2812 2813 if (nblks == 0) 2814 return (ENXIO); 2815 mtx_lock(&sw_dev_mtx); 2816 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2817 if (sp->sw_id == vp) { 2818 mtx_unlock(&sw_dev_mtx); 2819 return (EBUSY); 2820 } 2821 } 2822 mtx_unlock(&sw_dev_mtx); 2823 2824 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2825 #ifdef MAC 2826 error = mac_system_check_swapon(td->td_ucred, vp); 2827 if (error == 0) 2828 #endif 2829 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 2830 (void) VOP_UNLOCK(vp, 0); 2831 if (error) 2832 return (error); 2833 2834 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 2835 NODEV, 0); 2836 return (0); 2837 } 2838