1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (c) 1998 Matthew Dillon, 5 * Copyright (c) 1994 John S. Dyson 6 * Copyright (c) 1990 University of Utah. 7 * Copyright (c) 1982, 1986, 1989, 1993 8 * The Regents of the University of California. All rights reserved. 9 * 10 * This code is derived from software contributed to Berkeley by 11 * the Systems Programming Group of the University of Utah Computer 12 * Science Department. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. All advertising materials mentioning features or use of this software 23 * must display the following acknowledgement: 24 * This product includes software developed by the University of 25 * California, Berkeley and its contributors. 26 * 4. Neither the name of the University nor the names of its contributors 27 * may be used to endorse or promote products derived from this software 28 * without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 40 * SUCH DAMAGE. 41 * 42 * New Swap System 43 * Matthew Dillon 44 * 45 * Radix Bitmap 'blists'. 46 * 47 * - The new swapper uses the new radix bitmap code. This should scale 48 * to arbitrarily small or arbitrarily large swap spaces and an almost 49 * arbitrary degree of fragmentation. 50 * 51 * Features: 52 * 53 * - on the fly reallocation of swap during putpages. The new system 54 * does not try to keep previously allocated swap blocks for dirty 55 * pages. 56 * 57 * - on the fly deallocation of swap 58 * 59 * - No more garbage collection required. Unnecessarily allocated swap 60 * blocks only exist for dirty vm_page_t's now and these are already 61 * cycled (in a high-load system) by the pager. We also do on-the-fly 62 * removal of invalidated swap blocks when a page is destroyed 63 * or renamed. 64 * 65 * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$ 66 * 67 * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94 68 * @(#)vm_swap.c 8.5 (Berkeley) 2/17/94 69 */ 70 71 #include <sys/cdefs.h> 72 __FBSDID("$FreeBSD$"); 73 74 #include "opt_compat.h" 75 #include "opt_swap.h" 76 #include "opt_vm.h" 77 78 #include <sys/param.h> 79 #include <sys/systm.h> 80 #include <sys/conf.h> 81 #include <sys/kernel.h> 82 #include <sys/priv.h> 83 #include <sys/proc.h> 84 #include <sys/bio.h> 85 #include <sys/buf.h> 86 #include <sys/disk.h> 87 #include <sys/fcntl.h> 88 #include <sys/mount.h> 89 #include <sys/namei.h> 90 #include <sys/vnode.h> 91 #include <sys/malloc.h> 92 #include <sys/pctrie.h> 93 #include <sys/racct.h> 94 #include <sys/resource.h> 95 #include <sys/resourcevar.h> 96 #include <sys/rwlock.h> 97 #include <sys/sbuf.h> 98 #include <sys/sysctl.h> 99 #include <sys/sysproto.h> 100 #include <sys/blist.h> 101 #include <sys/lock.h> 102 #include <sys/sx.h> 103 #include <sys/vmmeter.h> 104 105 #include <security/mac/mac_framework.h> 106 107 #include <vm/vm.h> 108 #include <vm/pmap.h> 109 #include <vm/vm_map.h> 110 #include <vm/vm_kern.h> 111 #include <vm/vm_object.h> 112 #include <vm/vm_page.h> 113 #include <vm/vm_pager.h> 114 #include <vm/vm_pageout.h> 115 #include <vm/vm_param.h> 116 #include <vm/swap_pager.h> 117 #include <vm/vm_extern.h> 118 #include <vm/uma.h> 119 120 #include <geom/geom.h> 121 122 /* 123 * MAX_PAGEOUT_CLUSTER must be a power of 2 between 1 and 64. 124 * The 64-page limit is due to the radix code (kern/subr_blist.c). 125 */ 126 #ifndef MAX_PAGEOUT_CLUSTER 127 #define MAX_PAGEOUT_CLUSTER 32 128 #endif 129 130 #if !defined(SWB_NPAGES) 131 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER 132 #endif 133 134 #define SWAP_META_PAGES PCTRIE_COUNT 135 136 /* 137 * A swblk structure maps each page index within a 138 * SWAP_META_PAGES-aligned and sized range to the address of an 139 * on-disk swap block (or SWAPBLK_NONE). The collection of these 140 * mappings for an entire vm object is implemented as a pc-trie. 141 */ 142 struct swblk { 143 vm_pindex_t p; 144 daddr_t d[SWAP_META_PAGES]; 145 }; 146 147 static MALLOC_DEFINE(M_VMPGDATA, "vm_pgdata", "swap pager private data"); 148 static struct mtx sw_dev_mtx; 149 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 150 static struct swdevt *swdevhd; /* Allocate from here next */ 151 static int nswapdev; /* Number of swap devices */ 152 int swap_pager_avail; 153 static struct sx swdev_syscall_lock; /* serialize swap(on|off) */ 154 155 static vm_ooffset_t swap_total; 156 SYSCTL_QUAD(_vm, OID_AUTO, swap_total, CTLFLAG_RD, &swap_total, 0, 157 "Total amount of available swap storage."); 158 static vm_ooffset_t swap_reserved; 159 SYSCTL_QUAD(_vm, OID_AUTO, swap_reserved, CTLFLAG_RD, &swap_reserved, 0, 160 "Amount of swap storage needed to back all allocated anonymous memory."); 161 static int overcommit = 0; 162 SYSCTL_INT(_vm, VM_OVERCOMMIT, overcommit, CTLFLAG_RW, &overcommit, 0, 163 "Configure virtual memory overcommit behavior. See tuning(7) " 164 "for details."); 165 static unsigned long swzone; 166 SYSCTL_ULONG(_vm, OID_AUTO, swzone, CTLFLAG_RD, &swzone, 0, 167 "Actual size of swap metadata zone"); 168 static unsigned long swap_maxpages; 169 SYSCTL_ULONG(_vm, OID_AUTO, swap_maxpages, CTLFLAG_RD, &swap_maxpages, 0, 170 "Maximum amount of swap supported"); 171 172 /* bits from overcommit */ 173 #define SWAP_RESERVE_FORCE_ON (1 << 0) 174 #define SWAP_RESERVE_RLIMIT_ON (1 << 1) 175 #define SWAP_RESERVE_ALLOW_NONWIRED (1 << 2) 176 177 int 178 swap_reserve(vm_ooffset_t incr) 179 { 180 181 return (swap_reserve_by_cred(incr, curthread->td_ucred)); 182 } 183 184 int 185 swap_reserve_by_cred(vm_ooffset_t incr, struct ucred *cred) 186 { 187 vm_ooffset_t r, s; 188 int res, error; 189 static int curfail; 190 static struct timeval lastfail; 191 struct uidinfo *uip; 192 193 uip = cred->cr_ruidinfo; 194 195 if (incr & PAGE_MASK) 196 panic("swap_reserve: & PAGE_MASK"); 197 198 #ifdef RACCT 199 if (racct_enable) { 200 PROC_LOCK(curproc); 201 error = racct_add(curproc, RACCT_SWAP, incr); 202 PROC_UNLOCK(curproc); 203 if (error != 0) 204 return (0); 205 } 206 #endif 207 208 res = 0; 209 mtx_lock(&sw_dev_mtx); 210 r = swap_reserved + incr; 211 if (overcommit & SWAP_RESERVE_ALLOW_NONWIRED) { 212 s = vm_cnt.v_page_count - vm_cnt.v_free_reserved - vm_cnt.v_wire_count; 213 s *= PAGE_SIZE; 214 } else 215 s = 0; 216 s += swap_total; 217 if ((overcommit & SWAP_RESERVE_FORCE_ON) == 0 || r <= s || 218 (error = priv_check(curthread, PRIV_VM_SWAP_NOQUOTA)) == 0) { 219 res = 1; 220 swap_reserved = r; 221 } 222 mtx_unlock(&sw_dev_mtx); 223 224 if (res) { 225 UIDINFO_VMSIZE_LOCK(uip); 226 if ((overcommit & SWAP_RESERVE_RLIMIT_ON) != 0 && 227 uip->ui_vmsize + incr > lim_cur(curthread, RLIMIT_SWAP) && 228 priv_check(curthread, PRIV_VM_SWAP_NORLIMIT)) 229 res = 0; 230 else 231 uip->ui_vmsize += incr; 232 UIDINFO_VMSIZE_UNLOCK(uip); 233 if (!res) { 234 mtx_lock(&sw_dev_mtx); 235 swap_reserved -= incr; 236 mtx_unlock(&sw_dev_mtx); 237 } 238 } 239 if (!res && ppsratecheck(&lastfail, &curfail, 1)) { 240 printf("uid %d, pid %d: swap reservation for %jd bytes failed\n", 241 uip->ui_uid, curproc->p_pid, incr); 242 } 243 244 #ifdef RACCT 245 if (!res) { 246 PROC_LOCK(curproc); 247 racct_sub(curproc, RACCT_SWAP, incr); 248 PROC_UNLOCK(curproc); 249 } 250 #endif 251 252 return (res); 253 } 254 255 void 256 swap_reserve_force(vm_ooffset_t incr) 257 { 258 struct uidinfo *uip; 259 260 mtx_lock(&sw_dev_mtx); 261 swap_reserved += incr; 262 mtx_unlock(&sw_dev_mtx); 263 264 #ifdef RACCT 265 PROC_LOCK(curproc); 266 racct_add_force(curproc, RACCT_SWAP, incr); 267 PROC_UNLOCK(curproc); 268 #endif 269 270 uip = curthread->td_ucred->cr_ruidinfo; 271 PROC_LOCK(curproc); 272 UIDINFO_VMSIZE_LOCK(uip); 273 uip->ui_vmsize += incr; 274 UIDINFO_VMSIZE_UNLOCK(uip); 275 PROC_UNLOCK(curproc); 276 } 277 278 void 279 swap_release(vm_ooffset_t decr) 280 { 281 struct ucred *cred; 282 283 PROC_LOCK(curproc); 284 cred = curthread->td_ucred; 285 swap_release_by_cred(decr, cred); 286 PROC_UNLOCK(curproc); 287 } 288 289 void 290 swap_release_by_cred(vm_ooffset_t decr, struct ucred *cred) 291 { 292 struct uidinfo *uip; 293 294 uip = cred->cr_ruidinfo; 295 296 if (decr & PAGE_MASK) 297 panic("swap_release: & PAGE_MASK"); 298 299 mtx_lock(&sw_dev_mtx); 300 if (swap_reserved < decr) 301 panic("swap_reserved < decr"); 302 swap_reserved -= decr; 303 mtx_unlock(&sw_dev_mtx); 304 305 UIDINFO_VMSIZE_LOCK(uip); 306 if (uip->ui_vmsize < decr) 307 printf("negative vmsize for uid = %d\n", uip->ui_uid); 308 uip->ui_vmsize -= decr; 309 UIDINFO_VMSIZE_UNLOCK(uip); 310 311 racct_sub_cred(cred, RACCT_SWAP, decr); 312 } 313 314 #define SWM_FREE 0x02 /* free, period */ 315 #define SWM_POP 0x04 /* pop out */ 316 317 static int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 318 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 319 static int nsw_rcount; /* free read buffers */ 320 static int nsw_wcount_sync; /* limit write buffers / synchronous */ 321 static int nsw_wcount_async; /* limit write buffers / asynchronous */ 322 static int nsw_wcount_async_max;/* assigned maximum */ 323 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 324 325 static int sysctl_swap_async_max(SYSCTL_HANDLER_ARGS); 326 SYSCTL_PROC(_vm, OID_AUTO, swap_async_max, CTLTYPE_INT | CTLFLAG_RW | 327 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_async_max, "I", 328 "Maximum running async swap ops"); 329 static int sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS); 330 SYSCTL_PROC(_vm, OID_AUTO, swap_fragmentation, CTLTYPE_STRING | CTLFLAG_RD | 331 CTLFLAG_MPSAFE, NULL, 0, sysctl_swap_fragmentation, "A", 332 "Swap Fragmentation Info"); 333 334 static struct sx sw_alloc_sx; 335 336 /* 337 * "named" and "unnamed" anon region objects. Try to reduce the overhead 338 * of searching a named list by hashing it just a little. 339 */ 340 341 #define NOBJLISTS 8 342 343 #define NOBJLIST(handle) \ 344 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 345 346 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 347 static uma_zone_t swblk_zone; 348 static uma_zone_t swpctrie_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 void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 407 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, vm_pindex_t); 408 static void swp_pager_meta_free_all(vm_object_t); 409 static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 410 411 static void * 412 swblk_trie_alloc(struct pctrie *ptree) 413 { 414 415 return (uma_zalloc(swpctrie_zone, M_NOWAIT | (curproc == pageproc ? 416 M_USE_RESERVE : 0))); 417 } 418 419 static void 420 swblk_trie_free(struct pctrie *ptree, void *node) 421 { 422 423 uma_zfree(swpctrie_zone, node); 424 } 425 426 PCTRIE_DEFINE(SWAP, swblk, p, swblk_trie_alloc, swblk_trie_free); 427 428 /* 429 * SWP_SIZECHECK() - update swap_pager_full indication 430 * 431 * update the swap_pager_almost_full indication and warn when we are 432 * about to run out of swap space, using lowat/hiwat hysteresis. 433 * 434 * Clear swap_pager_full ( task killing ) indication when lowat is met. 435 * 436 * No restrictions on call 437 * This routine may not block. 438 */ 439 static void 440 swp_sizecheck(void) 441 { 442 443 if (swap_pager_avail < nswap_lowat) { 444 if (swap_pager_almost_full == 0) { 445 printf("swap_pager: out of swap space\n"); 446 swap_pager_almost_full = 1; 447 } 448 } else { 449 swap_pager_full = 0; 450 if (swap_pager_avail > nswap_hiwat) 451 swap_pager_almost_full = 0; 452 } 453 } 454 455 /* 456 * SWAP_PAGER_INIT() - initialize the swap pager! 457 * 458 * Expected to be started from system init. NOTE: This code is run 459 * before much else so be careful what you depend on. Most of the VM 460 * system has yet to be initialized at this point. 461 */ 462 static void 463 swap_pager_init(void) 464 { 465 /* 466 * Initialize object lists 467 */ 468 int i; 469 470 for (i = 0; i < NOBJLISTS; ++i) 471 TAILQ_INIT(&swap_pager_object_list[i]); 472 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 473 sx_init(&sw_alloc_sx, "swspsx"); 474 sx_init(&swdev_syscall_lock, "swsysc"); 475 } 476 477 /* 478 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 479 * 480 * Expected to be started from pageout process once, prior to entering 481 * its main loop. 482 */ 483 void 484 swap_pager_swap_init(void) 485 { 486 unsigned long n, n2; 487 488 /* 489 * Number of in-transit swap bp operations. Don't 490 * exhaust the pbufs completely. Make sure we 491 * initialize workable values (0 will work for hysteresis 492 * but it isn't very efficient). 493 * 494 * The nsw_cluster_max is constrained by the bp->b_pages[] 495 * array (MAXPHYS/PAGE_SIZE) and our locally defined 496 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 497 * constrained by the swap device interleave stripe size. 498 * 499 * Currently we hardwire nsw_wcount_async to 4. This limit is 500 * designed to prevent other I/O from having high latencies due to 501 * our pageout I/O. The value 4 works well for one or two active swap 502 * devices but is probably a little low if you have more. Even so, 503 * a higher value would probably generate only a limited improvement 504 * with three or four active swap devices since the system does not 505 * typically have to pageout at extreme bandwidths. We will want 506 * at least 2 per swap devices, and 4 is a pretty good value if you 507 * have one NFS swap device due to the command/ack latency over NFS. 508 * So it all works out pretty well. 509 */ 510 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER); 511 512 mtx_lock(&pbuf_mtx); 513 nsw_rcount = (nswbuf + 1) / 2; 514 nsw_wcount_sync = (nswbuf + 3) / 4; 515 nsw_wcount_async = 4; 516 nsw_wcount_async_max = nsw_wcount_async; 517 mtx_unlock(&pbuf_mtx); 518 519 /* 520 * Initialize our zone, guessing on the number we need based 521 * on the number of pages in the system. 522 */ 523 n = vm_cnt.v_page_count / 2; 524 if (maxswzone && n > maxswzone / sizeof(struct swblk)) 525 n = maxswzone / sizeof(struct swblk); 526 swpctrie_zone = uma_zcreate("swpctrie", pctrie_node_size(), NULL, NULL, 527 pctrie_zone_init, NULL, UMA_ALIGN_PTR, 528 UMA_ZONE_NOFREE | UMA_ZONE_VM); 529 if (swpctrie_zone == NULL) 530 panic("failed to create swap pctrie zone."); 531 swblk_zone = uma_zcreate("swblk", sizeof(struct swblk), NULL, NULL, 532 NULL, NULL, _Alignof(struct swblk) - 1, 533 UMA_ZONE_NOFREE | UMA_ZONE_VM); 534 if (swblk_zone == NULL) 535 panic("failed to create swap blk zone."); 536 n2 = n; 537 do { 538 if (uma_zone_reserve_kva(swblk_zone, n)) 539 break; 540 /* 541 * if the allocation failed, try a zone two thirds the 542 * size of the previous attempt. 543 */ 544 n -= ((n + 2) / 3); 545 } while (n > 0); 546 547 /* 548 * Often uma_zone_reserve_kva() cannot reserve exactly the 549 * requested size. Account for the difference when 550 * calculating swap_maxpages. 551 */ 552 n = uma_zone_get_max(swblk_zone); 553 554 if (n < n2) 555 printf("Swap blk zone entries reduced from %lu to %lu.\n", 556 n2, n); 557 swap_maxpages = n * SWAP_META_PAGES; 558 swzone = n * sizeof(struct swblk); 559 if (!uma_zone_reserve_kva(swpctrie_zone, n)) 560 printf("Cannot reserve swap pctrie zone, " 561 "reduce kern.maxswzone.\n"); 562 } 563 564 static vm_object_t 565 swap_pager_alloc_init(void *handle, struct ucred *cred, vm_ooffset_t size, 566 vm_ooffset_t offset) 567 { 568 vm_object_t object; 569 570 if (cred != NULL) { 571 if (!swap_reserve_by_cred(size, cred)) 572 return (NULL); 573 crhold(cred); 574 } 575 576 /* 577 * The un_pager.swp.swp_blks trie is initialized by 578 * vm_object_allocate() to ensure the correct order of 579 * visibility to other threads. 580 */ 581 object = vm_object_allocate(OBJT_SWAP, OFF_TO_IDX(offset + 582 PAGE_MASK + size)); 583 584 object->handle = handle; 585 if (cred != NULL) { 586 object->cred = cred; 587 object->charge = size; 588 } 589 return (object); 590 } 591 592 /* 593 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 594 * its metadata structures. 595 * 596 * This routine is called from the mmap and fork code to create a new 597 * OBJT_SWAP object. 598 * 599 * This routine must ensure that no live duplicate is created for 600 * the named object request, which is protected against by 601 * holding the sw_alloc_sx lock in case handle != NULL. 602 */ 603 static vm_object_t 604 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 605 vm_ooffset_t offset, struct ucred *cred) 606 { 607 vm_object_t object; 608 609 if (handle != NULL) { 610 /* 611 * Reference existing named region or allocate new one. There 612 * should not be a race here against swp_pager_meta_build() 613 * as called from vm_page_remove() in regards to the lookup 614 * of the handle. 615 */ 616 sx_xlock(&sw_alloc_sx); 617 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 618 if (object == NULL) { 619 object = swap_pager_alloc_init(handle, cred, size, 620 offset); 621 if (object != NULL) { 622 TAILQ_INSERT_TAIL(NOBJLIST(object->handle), 623 object, pager_object_list); 624 } 625 } 626 sx_xunlock(&sw_alloc_sx); 627 } else { 628 object = swap_pager_alloc_init(handle, cred, size, offset); 629 } 630 return (object); 631 } 632 633 /* 634 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 635 * 636 * The swap backing for the object is destroyed. The code is 637 * designed such that we can reinstantiate it later, but this 638 * routine is typically called only when the entire object is 639 * about to be destroyed. 640 * 641 * The object must be locked. 642 */ 643 static void 644 swap_pager_dealloc(vm_object_t object) 645 { 646 647 VM_OBJECT_ASSERT_WLOCKED(object); 648 KASSERT((object->flags & OBJ_DEAD) != 0, ("dealloc of reachable obj")); 649 650 /* 651 * Remove from list right away so lookups will fail if we block for 652 * pageout completion. 653 */ 654 if (object->handle != NULL) { 655 VM_OBJECT_WUNLOCK(object); 656 sx_xlock(&sw_alloc_sx); 657 TAILQ_REMOVE(NOBJLIST(object->handle), object, 658 pager_object_list); 659 sx_xunlock(&sw_alloc_sx); 660 VM_OBJECT_WLOCK(object); 661 } 662 663 vm_object_pip_wait(object, "swpdea"); 664 665 /* 666 * Free all remaining metadata. We only bother to free it from 667 * the swap meta data. We do not attempt to free swapblk's still 668 * associated with vm_page_t's for this object. We do not care 669 * if paging is still in progress on some objects. 670 */ 671 swp_pager_meta_free_all(object); 672 object->handle = NULL; 673 object->type = OBJT_DEAD; 674 } 675 676 /************************************************************************ 677 * SWAP PAGER BITMAP ROUTINES * 678 ************************************************************************/ 679 680 /* 681 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 682 * 683 * Allocate swap for the requested number of pages. The starting 684 * swap block number (a page index) is returned or SWAPBLK_NONE 685 * if the allocation failed. 686 * 687 * Also has the side effect of advising that somebody made a mistake 688 * when they configured swap and didn't configure enough. 689 * 690 * This routine may not sleep. 691 * 692 * We allocate in round-robin fashion from the configured devices. 693 */ 694 static daddr_t 695 swp_pager_getswapspace(int npages) 696 { 697 daddr_t blk; 698 struct swdevt *sp; 699 int i; 700 701 blk = SWAPBLK_NONE; 702 mtx_lock(&sw_dev_mtx); 703 sp = swdevhd; 704 for (i = 0; i < nswapdev; i++) { 705 if (sp == NULL) 706 sp = TAILQ_FIRST(&swtailq); 707 if (!(sp->sw_flags & SW_CLOSING)) { 708 blk = blist_alloc(sp->sw_blist, npages); 709 if (blk != SWAPBLK_NONE) { 710 blk += sp->sw_first; 711 sp->sw_used += npages; 712 swap_pager_avail -= npages; 713 swp_sizecheck(); 714 swdevhd = TAILQ_NEXT(sp, sw_list); 715 goto done; 716 } 717 } 718 sp = TAILQ_NEXT(sp, sw_list); 719 } 720 if (swap_pager_full != 2) { 721 printf("swap_pager_getswapspace(%d): failed\n", npages); 722 swap_pager_full = 2; 723 swap_pager_almost_full = 1; 724 } 725 swdevhd = NULL; 726 done: 727 mtx_unlock(&sw_dev_mtx); 728 return (blk); 729 } 730 731 static int 732 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 733 { 734 735 return (blk >= sp->sw_first && blk < sp->sw_end); 736 } 737 738 static void 739 swp_pager_strategy(struct buf *bp) 740 { 741 struct swdevt *sp; 742 743 mtx_lock(&sw_dev_mtx); 744 TAILQ_FOREACH(sp, &swtailq, sw_list) { 745 if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) { 746 mtx_unlock(&sw_dev_mtx); 747 if ((sp->sw_flags & SW_UNMAPPED) != 0 && 748 unmapped_buf_allowed) { 749 bp->b_data = unmapped_buf; 750 bp->b_offset = 0; 751 } else { 752 pmap_qenter((vm_offset_t)bp->b_data, 753 &bp->b_pages[0], bp->b_bcount / PAGE_SIZE); 754 } 755 sp->sw_strategy(bp, sp); 756 return; 757 } 758 } 759 panic("Swapdev not found"); 760 } 761 762 763 /* 764 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 765 * 766 * This routine returns the specified swap blocks back to the bitmap. 767 * 768 * This routine may not sleep. 769 */ 770 static void 771 swp_pager_freeswapspace(daddr_t blk, int npages) 772 { 773 struct swdevt *sp; 774 775 mtx_lock(&sw_dev_mtx); 776 TAILQ_FOREACH(sp, &swtailq, sw_list) { 777 if (blk >= sp->sw_first && blk < sp->sw_end) { 778 sp->sw_used -= npages; 779 /* 780 * If we are attempting to stop swapping on 781 * this device, we don't want to mark any 782 * blocks free lest they be reused. 783 */ 784 if ((sp->sw_flags & SW_CLOSING) == 0) { 785 blist_free(sp->sw_blist, blk - sp->sw_first, 786 npages); 787 swap_pager_avail += npages; 788 swp_sizecheck(); 789 } 790 mtx_unlock(&sw_dev_mtx); 791 return; 792 } 793 } 794 panic("Swapdev not found"); 795 } 796 797 /* 798 * SYSCTL_SWAP_FRAGMENTATION() - produce raw swap space stats 799 */ 800 static int 801 sysctl_swap_fragmentation(SYSCTL_HANDLER_ARGS) 802 { 803 struct sbuf sbuf; 804 struct swdevt *sp; 805 const char *devname; 806 int error; 807 808 error = sysctl_wire_old_buffer(req, 0); 809 if (error != 0) 810 return (error); 811 sbuf_new_for_sysctl(&sbuf, NULL, 128, req); 812 mtx_lock(&sw_dev_mtx); 813 TAILQ_FOREACH(sp, &swtailq, sw_list) { 814 if (vn_isdisk(sp->sw_vp, NULL)) 815 devname = devtoname(sp->sw_vp->v_rdev); 816 else 817 devname = "[file]"; 818 sbuf_printf(&sbuf, "\nFree space on device %s:\n", devname); 819 blist_stats(sp->sw_blist, &sbuf); 820 } 821 mtx_unlock(&sw_dev_mtx); 822 error = sbuf_finish(&sbuf); 823 sbuf_delete(&sbuf); 824 return (error); 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 && srcobject->handle != NULL) { 920 vm_object_pip_add(srcobject, 1); 921 VM_OBJECT_WUNLOCK(srcobject); 922 vm_object_pip_add(dstobject, 1); 923 VM_OBJECT_WUNLOCK(dstobject); 924 sx_xlock(&sw_alloc_sx); 925 TAILQ_REMOVE(NOBJLIST(srcobject->handle), srcobject, 926 pager_object_list); 927 sx_xunlock(&sw_alloc_sx); 928 VM_OBJECT_WLOCK(dstobject); 929 vm_object_pip_wakeup(dstobject); 930 VM_OBJECT_WLOCK(srcobject); 931 vm_object_pip_wakeup(srcobject); 932 } 933 934 /* 935 * transfer source to destination. 936 */ 937 for (i = 0; i < dstobject->size; ++i) { 938 daddr_t dstaddr; 939 940 /* 941 * Locate (without changing) the swapblk on the destination, 942 * unless it is invalid in which case free it silently, or 943 * if the destination is a resident page, in which case the 944 * source is thrown away. 945 */ 946 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 947 948 if (dstaddr == SWAPBLK_NONE) { 949 /* 950 * Destination has no swapblk and is not resident, 951 * copy source. 952 */ 953 daddr_t srcaddr; 954 955 srcaddr = swp_pager_meta_ctl( 956 srcobject, 957 i + offset, 958 SWM_POP 959 ); 960 961 if (srcaddr != SWAPBLK_NONE) { 962 /* 963 * swp_pager_meta_build() can sleep. 964 */ 965 vm_object_pip_add(srcobject, 1); 966 VM_OBJECT_WUNLOCK(srcobject); 967 vm_object_pip_add(dstobject, 1); 968 swp_pager_meta_build(dstobject, i, srcaddr); 969 vm_object_pip_wakeup(dstobject); 970 VM_OBJECT_WLOCK(srcobject); 971 vm_object_pip_wakeup(srcobject); 972 } 973 } else { 974 /* 975 * Destination has valid swapblk or it is represented 976 * by a resident page. We destroy the sourceblock. 977 */ 978 979 swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE); 980 } 981 } 982 983 /* 984 * Free left over swap blocks in source. 985 * 986 * We have to revert the type to OBJT_DEFAULT so we do not accidentally 987 * double-remove the object from the swap queues. 988 */ 989 if (destroysource) { 990 swp_pager_meta_free_all(srcobject); 991 /* 992 * Reverting the type is not necessary, the caller is going 993 * to destroy srcobject directly, but I'm doing it here 994 * for consistency since we've removed the object from its 995 * queues. 996 */ 997 srcobject->type = OBJT_DEFAULT; 998 } 999 } 1000 1001 /* 1002 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 1003 * the requested page. 1004 * 1005 * We determine whether good backing store exists for the requested 1006 * page and return TRUE if it does, FALSE if it doesn't. 1007 * 1008 * If TRUE, we also try to determine how much valid, contiguous backing 1009 * store exists before and after the requested page. 1010 */ 1011 static boolean_t 1012 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 1013 int *after) 1014 { 1015 daddr_t blk, blk0; 1016 int i; 1017 1018 VM_OBJECT_ASSERT_LOCKED(object); 1019 1020 /* 1021 * do we have good backing store at the requested index ? 1022 */ 1023 blk0 = swp_pager_meta_ctl(object, pindex, 0); 1024 if (blk0 == SWAPBLK_NONE) { 1025 if (before) 1026 *before = 0; 1027 if (after) 1028 *after = 0; 1029 return (FALSE); 1030 } 1031 1032 /* 1033 * find backwards-looking contiguous good backing store 1034 */ 1035 if (before != NULL) { 1036 for (i = 1; i < SWB_NPAGES; i++) { 1037 if (i > pindex) 1038 break; 1039 blk = swp_pager_meta_ctl(object, pindex - i, 0); 1040 if (blk != blk0 - i) 1041 break; 1042 } 1043 *before = i - 1; 1044 } 1045 1046 /* 1047 * find forward-looking contiguous good backing store 1048 */ 1049 if (after != NULL) { 1050 for (i = 1; i < SWB_NPAGES; i++) { 1051 blk = swp_pager_meta_ctl(object, pindex + i, 0); 1052 if (blk != blk0 + i) 1053 break; 1054 } 1055 *after = i - 1; 1056 } 1057 return (TRUE); 1058 } 1059 1060 /* 1061 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 1062 * 1063 * This removes any associated swap backing store, whether valid or 1064 * not, from the page. 1065 * 1066 * This routine is typically called when a page is made dirty, at 1067 * which point any associated swap can be freed. MADV_FREE also 1068 * calls us in a special-case situation 1069 * 1070 * NOTE!!! If the page is clean and the swap was valid, the caller 1071 * should make the page dirty before calling this routine. This routine 1072 * does NOT change the m->dirty status of the page. Also: MADV_FREE 1073 * depends on it. 1074 * 1075 * This routine may not sleep. 1076 * 1077 * The object containing the page must be locked. 1078 */ 1079 static void 1080 swap_pager_unswapped(vm_page_t m) 1081 { 1082 1083 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); 1084 } 1085 1086 /* 1087 * swap_pager_getpages() - bring pages in from swap 1088 * 1089 * Attempt to page in the pages in array "m" of length "count". The caller 1090 * may optionally specify that additional pages preceding and succeeding 1091 * the specified range be paged in. The number of such pages is returned 1092 * in the "rbehind" and "rahead" parameters, and they will be in the 1093 * inactive queue upon return. 1094 * 1095 * The pages in "m" must be busied and will remain busied upon return. 1096 */ 1097 static int 1098 swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind, 1099 int *rahead) 1100 { 1101 struct buf *bp; 1102 vm_page_t mpred, msucc, p; 1103 vm_pindex_t pindex; 1104 daddr_t blk; 1105 int i, j, maxahead, maxbehind, reqcount, shift; 1106 1107 reqcount = count; 1108 1109 VM_OBJECT_WUNLOCK(object); 1110 bp = getpbuf(&nsw_rcount); 1111 VM_OBJECT_WLOCK(object); 1112 1113 if (!swap_pager_haspage(object, m[0]->pindex, &maxbehind, &maxahead)) { 1114 relpbuf(bp, &nsw_rcount); 1115 return (VM_PAGER_FAIL); 1116 } 1117 1118 /* 1119 * Clip the readahead and readbehind ranges to exclude resident pages. 1120 */ 1121 if (rahead != NULL) { 1122 KASSERT(reqcount - 1 <= maxahead, 1123 ("page count %d extends beyond swap block", reqcount)); 1124 *rahead = imin(*rahead, maxahead - (reqcount - 1)); 1125 pindex = m[reqcount - 1]->pindex; 1126 msucc = TAILQ_NEXT(m[reqcount - 1], listq); 1127 if (msucc != NULL && msucc->pindex - pindex - 1 < *rahead) 1128 *rahead = msucc->pindex - pindex - 1; 1129 } 1130 if (rbehind != NULL) { 1131 *rbehind = imin(*rbehind, maxbehind); 1132 pindex = m[0]->pindex; 1133 mpred = TAILQ_PREV(m[0], pglist, listq); 1134 if (mpred != NULL && pindex - mpred->pindex - 1 < *rbehind) 1135 *rbehind = pindex - mpred->pindex - 1; 1136 } 1137 1138 /* 1139 * Allocate readahead and readbehind pages. 1140 */ 1141 shift = rbehind != NULL ? *rbehind : 0; 1142 if (shift != 0) { 1143 for (i = 1; i <= shift; i++) { 1144 p = vm_page_alloc(object, m[0]->pindex - i, 1145 VM_ALLOC_NORMAL); 1146 if (p == NULL) { 1147 /* Shift allocated pages to the left. */ 1148 for (j = 0; j < i - 1; j++) 1149 bp->b_pages[j] = 1150 bp->b_pages[j + shift - i + 1]; 1151 break; 1152 } 1153 bp->b_pages[shift - i] = p; 1154 } 1155 shift = i - 1; 1156 *rbehind = shift; 1157 } 1158 for (i = 0; i < reqcount; i++) 1159 bp->b_pages[i + shift] = m[i]; 1160 if (rahead != NULL) { 1161 for (i = 0; i < *rahead; i++) { 1162 p = vm_page_alloc(object, 1163 m[reqcount - 1]->pindex + i + 1, VM_ALLOC_NORMAL); 1164 if (p == NULL) 1165 break; 1166 bp->b_pages[shift + reqcount + i] = p; 1167 } 1168 *rahead = i; 1169 } 1170 if (rbehind != NULL) 1171 count += *rbehind; 1172 if (rahead != NULL) 1173 count += *rahead; 1174 1175 vm_object_pip_add(object, count); 1176 1177 for (i = 0; i < count; i++) 1178 bp->b_pages[i]->oflags |= VPO_SWAPINPROG; 1179 1180 pindex = bp->b_pages[0]->pindex; 1181 blk = swp_pager_meta_ctl(object, pindex, 0); 1182 KASSERT(blk != SWAPBLK_NONE, 1183 ("no swap blocking containing %p(%jx)", object, (uintmax_t)pindex)); 1184 1185 VM_OBJECT_WUNLOCK(object); 1186 1187 bp->b_flags |= B_PAGING; 1188 bp->b_iocmd = BIO_READ; 1189 bp->b_iodone = swp_pager_async_iodone; 1190 bp->b_rcred = crhold(thread0.td_ucred); 1191 bp->b_wcred = crhold(thread0.td_ucred); 1192 bp->b_blkno = blk; 1193 bp->b_bcount = PAGE_SIZE * count; 1194 bp->b_bufsize = PAGE_SIZE * count; 1195 bp->b_npages = count; 1196 bp->b_pgbefore = rbehind != NULL ? *rbehind : 0; 1197 bp->b_pgafter = rahead != NULL ? *rahead : 0; 1198 1199 VM_CNT_INC(v_swapin); 1200 VM_CNT_ADD(v_swappgsin, count); 1201 1202 /* 1203 * perform the I/O. NOTE!!! bp cannot be considered valid after 1204 * this point because we automatically release it on completion. 1205 * Instead, we look at the one page we are interested in which we 1206 * still hold a lock on even through the I/O completion. 1207 * 1208 * The other pages in our m[] array are also released on completion, 1209 * so we cannot assume they are valid anymore either. 1210 * 1211 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1212 */ 1213 BUF_KERNPROC(bp); 1214 swp_pager_strategy(bp); 1215 1216 /* 1217 * Wait for the pages we want to complete. VPO_SWAPINPROG is always 1218 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1219 * is set in the metadata for each page in the request. 1220 */ 1221 VM_OBJECT_WLOCK(object); 1222 while ((m[0]->oflags & VPO_SWAPINPROG) != 0) { 1223 m[0]->oflags |= VPO_SWAPSLEEP; 1224 VM_CNT_INC(v_intrans); 1225 if (VM_OBJECT_SLEEP(object, &object->paging_in_progress, PSWP, 1226 "swread", hz * 20)) { 1227 printf( 1228 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1229 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1230 } 1231 } 1232 1233 /* 1234 * If we had an unrecoverable read error pages will not be valid. 1235 */ 1236 for (i = 0; i < reqcount; i++) 1237 if (m[i]->valid != VM_PAGE_BITS_ALL) 1238 return (VM_PAGER_ERROR); 1239 1240 return (VM_PAGER_OK); 1241 1242 /* 1243 * A final note: in a low swap situation, we cannot deallocate swap 1244 * and mark a page dirty here because the caller is likely to mark 1245 * the page clean when we return, causing the page to possibly revert 1246 * to all-zero's later. 1247 */ 1248 } 1249 1250 /* 1251 * swap_pager_getpages_async(): 1252 * 1253 * Right now this is emulation of asynchronous operation on top of 1254 * swap_pager_getpages(). 1255 */ 1256 static int 1257 swap_pager_getpages_async(vm_object_t object, vm_page_t *m, int count, 1258 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg) 1259 { 1260 int r, error; 1261 1262 r = swap_pager_getpages(object, m, count, rbehind, rahead); 1263 VM_OBJECT_WUNLOCK(object); 1264 switch (r) { 1265 case VM_PAGER_OK: 1266 error = 0; 1267 break; 1268 case VM_PAGER_ERROR: 1269 error = EIO; 1270 break; 1271 case VM_PAGER_FAIL: 1272 error = EINVAL; 1273 break; 1274 default: 1275 panic("unhandled swap_pager_getpages() error %d", r); 1276 } 1277 (iodone)(arg, m, count, error); 1278 VM_OBJECT_WLOCK(object); 1279 1280 return (r); 1281 } 1282 1283 /* 1284 * swap_pager_putpages: 1285 * 1286 * Assign swap (if necessary) and initiate I/O on the specified pages. 1287 * 1288 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1289 * are automatically converted to SWAP objects. 1290 * 1291 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1292 * vm_page reservation system coupled with properly written VFS devices 1293 * should ensure that no low-memory deadlock occurs. This is an area 1294 * which needs work. 1295 * 1296 * The parent has N vm_object_pip_add() references prior to 1297 * calling us and will remove references for rtvals[] that are 1298 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1299 * completion. 1300 * 1301 * The parent has soft-busy'd the pages it passes us and will unbusy 1302 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1303 * We need to unbusy the rest on I/O completion. 1304 */ 1305 static void 1306 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1307 int flags, int *rtvals) 1308 { 1309 int i, n; 1310 boolean_t sync; 1311 1312 if (count && m[0]->object != object) { 1313 panic("swap_pager_putpages: object mismatch %p/%p", 1314 object, 1315 m[0]->object 1316 ); 1317 } 1318 1319 /* 1320 * Step 1 1321 * 1322 * Turn object into OBJT_SWAP 1323 * check for bogus sysops 1324 * force sync if not pageout process 1325 */ 1326 if (object->type != OBJT_SWAP) 1327 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1328 VM_OBJECT_WUNLOCK(object); 1329 1330 n = 0; 1331 if (curproc != pageproc) 1332 sync = TRUE; 1333 else 1334 sync = (flags & VM_PAGER_PUT_SYNC) != 0; 1335 1336 /* 1337 * Step 2 1338 * 1339 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1340 * The page is left dirty until the pageout operation completes 1341 * successfully. 1342 */ 1343 for (i = 0; i < count; i += n) { 1344 int j; 1345 struct buf *bp; 1346 daddr_t blk; 1347 1348 /* 1349 * Maximum I/O size is limited by a number of factors. 1350 */ 1351 n = min(BLIST_MAX_ALLOC, count - i); 1352 n = min(n, nsw_cluster_max); 1353 1354 /* 1355 * Get biggest block of swap we can. If we fail, fall 1356 * back and try to allocate a smaller block. Don't go 1357 * overboard trying to allocate space if it would overly 1358 * fragment swap. 1359 */ 1360 while ( 1361 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE && 1362 n > 4 1363 ) { 1364 n >>= 1; 1365 } 1366 if (blk == SWAPBLK_NONE) { 1367 for (j = 0; j < n; ++j) 1368 rtvals[i+j] = VM_PAGER_FAIL; 1369 continue; 1370 } 1371 1372 /* 1373 * All I/O parameters have been satisfied, build the I/O 1374 * request and assign the swap space. 1375 */ 1376 if (sync == TRUE) { 1377 bp = getpbuf(&nsw_wcount_sync); 1378 } else { 1379 bp = getpbuf(&nsw_wcount_async); 1380 bp->b_flags = B_ASYNC; 1381 } 1382 bp->b_flags |= B_PAGING; 1383 bp->b_iocmd = BIO_WRITE; 1384 1385 bp->b_rcred = crhold(thread0.td_ucred); 1386 bp->b_wcred = crhold(thread0.td_ucred); 1387 bp->b_bcount = PAGE_SIZE * n; 1388 bp->b_bufsize = PAGE_SIZE * n; 1389 bp->b_blkno = blk; 1390 1391 VM_OBJECT_WLOCK(object); 1392 for (j = 0; j < n; ++j) { 1393 vm_page_t mreq = m[i+j]; 1394 1395 swp_pager_meta_build( 1396 mreq->object, 1397 mreq->pindex, 1398 blk + j 1399 ); 1400 MPASS(mreq->dirty == VM_PAGE_BITS_ALL); 1401 mreq->oflags |= VPO_SWAPINPROG; 1402 bp->b_pages[j] = mreq; 1403 } 1404 VM_OBJECT_WUNLOCK(object); 1405 bp->b_npages = n; 1406 /* 1407 * Must set dirty range for NFS to work. 1408 */ 1409 bp->b_dirtyoff = 0; 1410 bp->b_dirtyend = bp->b_bcount; 1411 1412 VM_CNT_INC(v_swapout); 1413 VM_CNT_ADD(v_swappgsout, bp->b_npages); 1414 1415 /* 1416 * We unconditionally set rtvals[] to VM_PAGER_PEND so that we 1417 * can call the async completion routine at the end of a 1418 * synchronous I/O operation. Otherwise, our caller would 1419 * perform duplicate unbusy and wakeup operations on the page 1420 * and object, respectively. 1421 */ 1422 for (j = 0; j < n; j++) 1423 rtvals[i + j] = VM_PAGER_PEND; 1424 1425 /* 1426 * asynchronous 1427 * 1428 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1429 */ 1430 if (sync == FALSE) { 1431 bp->b_iodone = swp_pager_async_iodone; 1432 BUF_KERNPROC(bp); 1433 swp_pager_strategy(bp); 1434 continue; 1435 } 1436 1437 /* 1438 * synchronous 1439 * 1440 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1441 */ 1442 bp->b_iodone = bdone; 1443 swp_pager_strategy(bp); 1444 1445 /* 1446 * Wait for the sync I/O to complete. 1447 */ 1448 bwait(bp, PVM, "swwrt"); 1449 1450 /* 1451 * Now that we are through with the bp, we can call the 1452 * normal async completion, which frees everything up. 1453 */ 1454 swp_pager_async_iodone(bp); 1455 } 1456 VM_OBJECT_WLOCK(object); 1457 } 1458 1459 /* 1460 * swp_pager_async_iodone: 1461 * 1462 * Completion routine for asynchronous reads and writes from/to swap. 1463 * Also called manually by synchronous code to finish up a bp. 1464 * 1465 * This routine may not sleep. 1466 */ 1467 static void 1468 swp_pager_async_iodone(struct buf *bp) 1469 { 1470 int i; 1471 vm_object_t object = NULL; 1472 1473 /* 1474 * report error 1475 */ 1476 if (bp->b_ioflags & BIO_ERROR) { 1477 printf( 1478 "swap_pager: I/O error - %s failed; blkno %ld," 1479 "size %ld, error %d\n", 1480 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1481 (long)bp->b_blkno, 1482 (long)bp->b_bcount, 1483 bp->b_error 1484 ); 1485 } 1486 1487 /* 1488 * remove the mapping for kernel virtual 1489 */ 1490 if (buf_mapped(bp)) 1491 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1492 else 1493 bp->b_data = bp->b_kvabase; 1494 1495 if (bp->b_npages) { 1496 object = bp->b_pages[0]->object; 1497 VM_OBJECT_WLOCK(object); 1498 } 1499 1500 /* 1501 * cleanup pages. If an error occurs writing to swap, we are in 1502 * very serious trouble. If it happens to be a disk error, though, 1503 * we may be able to recover by reassigning the swap later on. So 1504 * in this case we remove the m->swapblk assignment for the page 1505 * but do not free it in the rlist. The errornous block(s) are thus 1506 * never reallocated as swap. Redirty the page and continue. 1507 */ 1508 for (i = 0; i < bp->b_npages; ++i) { 1509 vm_page_t m = bp->b_pages[i]; 1510 1511 m->oflags &= ~VPO_SWAPINPROG; 1512 if (m->oflags & VPO_SWAPSLEEP) { 1513 m->oflags &= ~VPO_SWAPSLEEP; 1514 wakeup(&object->paging_in_progress); 1515 } 1516 1517 if (bp->b_ioflags & BIO_ERROR) { 1518 /* 1519 * If an error occurs I'd love to throw the swapblk 1520 * away without freeing it back to swapspace, so it 1521 * can never be used again. But I can't from an 1522 * interrupt. 1523 */ 1524 if (bp->b_iocmd == BIO_READ) { 1525 /* 1526 * NOTE: for reads, m->dirty will probably 1527 * be overridden by the original caller of 1528 * getpages so don't play cute tricks here. 1529 */ 1530 m->valid = 0; 1531 } else { 1532 /* 1533 * If a write error occurs, reactivate page 1534 * so it doesn't clog the inactive list, 1535 * then finish the I/O. 1536 */ 1537 MPASS(m->dirty == VM_PAGE_BITS_ALL); 1538 vm_page_lock(m); 1539 vm_page_activate(m); 1540 vm_page_unlock(m); 1541 vm_page_sunbusy(m); 1542 } 1543 } else if (bp->b_iocmd == BIO_READ) { 1544 /* 1545 * NOTE: for reads, m->dirty will probably be 1546 * overridden by the original caller of getpages so 1547 * we cannot set them in order to free the underlying 1548 * swap in a low-swap situation. I don't think we'd 1549 * want to do that anyway, but it was an optimization 1550 * that existed in the old swapper for a time before 1551 * it got ripped out due to precisely this problem. 1552 */ 1553 KASSERT(!pmap_page_is_mapped(m), 1554 ("swp_pager_async_iodone: page %p is mapped", m)); 1555 KASSERT(m->dirty == 0, 1556 ("swp_pager_async_iodone: page %p is dirty", m)); 1557 1558 m->valid = VM_PAGE_BITS_ALL; 1559 if (i < bp->b_pgbefore || 1560 i >= bp->b_npages - bp->b_pgafter) 1561 vm_page_readahead_finish(m); 1562 } else { 1563 /* 1564 * For write success, clear the dirty 1565 * status, then finish the I/O ( which decrements the 1566 * busy count and possibly wakes waiter's up ). 1567 * A page is only written to swap after a period of 1568 * inactivity. Therefore, we do not expect it to be 1569 * reused. 1570 */ 1571 KASSERT(!pmap_page_is_write_mapped(m), 1572 ("swp_pager_async_iodone: page %p is not write" 1573 " protected", m)); 1574 vm_page_undirty(m); 1575 vm_page_lock(m); 1576 vm_page_deactivate_noreuse(m); 1577 vm_page_unlock(m); 1578 vm_page_sunbusy(m); 1579 } 1580 } 1581 1582 /* 1583 * adjust pip. NOTE: the original parent may still have its own 1584 * pip refs on the object. 1585 */ 1586 if (object != NULL) { 1587 vm_object_pip_wakeupn(object, bp->b_npages); 1588 VM_OBJECT_WUNLOCK(object); 1589 } 1590 1591 /* 1592 * swapdev_strategy() manually sets b_vp and b_bufobj before calling 1593 * bstrategy(). Set them back to NULL now we're done with it, or we'll 1594 * trigger a KASSERT in relpbuf(). 1595 */ 1596 if (bp->b_vp) { 1597 bp->b_vp = NULL; 1598 bp->b_bufobj = NULL; 1599 } 1600 /* 1601 * release the physical I/O buffer 1602 */ 1603 relpbuf( 1604 bp, 1605 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount : 1606 ((bp->b_flags & B_ASYNC) ? 1607 &nsw_wcount_async : 1608 &nsw_wcount_sync 1609 ) 1610 ) 1611 ); 1612 } 1613 1614 int 1615 swap_pager_nswapdev(void) 1616 { 1617 1618 return (nswapdev); 1619 } 1620 1621 /* 1622 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in 1623 * 1624 * This routine dissociates the page at the given index within an object 1625 * from its backing store, paging it in if it does not reside in memory. 1626 * If the page is paged in, it is marked dirty and placed in the laundry 1627 * queue. The page is marked dirty because it no longer has backing 1628 * store. It is placed in the laundry queue because it has not been 1629 * accessed recently. Otherwise, it would already reside in memory. 1630 * 1631 * We also attempt to swap in all other pages in the swap block. 1632 * However, we only guarantee that the one at the specified index is 1633 * paged in. 1634 * 1635 * XXX - The code to page the whole block in doesn't work, so we 1636 * revert to the one-by-one behavior for now. Sigh. 1637 */ 1638 static inline void 1639 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex) 1640 { 1641 vm_page_t m; 1642 1643 vm_object_pip_add(object, 1); 1644 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL); 1645 if (m->valid == VM_PAGE_BITS_ALL) { 1646 vm_object_pip_wakeup(object); 1647 vm_page_dirty(m); 1648 #ifdef INVARIANTS 1649 vm_page_lock(m); 1650 if (m->wire_count == 0 && m->queue == PQ_NONE) 1651 panic("page %p is neither wired nor queued", m); 1652 vm_page_unlock(m); 1653 #endif 1654 vm_page_xunbusy(m); 1655 vm_pager_page_unswapped(m); 1656 return; 1657 } 1658 1659 if (swap_pager_getpages(object, &m, 1, NULL, NULL) != VM_PAGER_OK) 1660 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/ 1661 vm_object_pip_wakeup(object); 1662 vm_page_dirty(m); 1663 vm_page_lock(m); 1664 vm_page_launder(m); 1665 vm_page_unlock(m); 1666 vm_page_xunbusy(m); 1667 vm_pager_page_unswapped(m); 1668 } 1669 1670 /* 1671 * swap_pager_swapoff: 1672 * 1673 * Page in all of the pages that have been paged out to the 1674 * given device. The corresponding blocks in the bitmap must be 1675 * marked as allocated and the device must be flagged SW_CLOSING. 1676 * There may be no processes swapped out to the device. 1677 * 1678 * This routine may block. 1679 */ 1680 static void 1681 swap_pager_swapoff(struct swdevt *sp) 1682 { 1683 struct swblk *sb; 1684 vm_object_t object; 1685 vm_pindex_t pi; 1686 int i, retries; 1687 1688 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 1689 1690 retries = 0; 1691 full_rescan: 1692 mtx_lock(&vm_object_list_mtx); 1693 TAILQ_FOREACH(object, &vm_object_list, object_list) { 1694 if (object->type != OBJT_SWAP) 1695 continue; 1696 mtx_unlock(&vm_object_list_mtx); 1697 /* Depends on type-stability. */ 1698 VM_OBJECT_WLOCK(object); 1699 1700 /* 1701 * Dead objects are eventually terminated on their own. 1702 */ 1703 if ((object->flags & OBJ_DEAD) != 0) 1704 goto next_obj; 1705 1706 /* 1707 * Sync with fences placed after pctrie 1708 * initialization. We must not access pctrie below 1709 * unless we checked that our object is swap and not 1710 * dead. 1711 */ 1712 atomic_thread_fence_acq(); 1713 if (object->type != OBJT_SWAP) 1714 goto next_obj; 1715 1716 for (pi = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1717 &object->un_pager.swp.swp_blks, pi)) != NULL; ) { 1718 pi = sb->p + SWAP_META_PAGES; 1719 for (i = 0; i < SWAP_META_PAGES; i++) { 1720 if (sb->d[i] == SWAPBLK_NONE) 1721 continue; 1722 if (swp_pager_isondev(sb->d[i], sp)) 1723 swp_pager_force_pagein(object, 1724 sb->p + i); 1725 } 1726 } 1727 next_obj: 1728 VM_OBJECT_WUNLOCK(object); 1729 mtx_lock(&vm_object_list_mtx); 1730 } 1731 mtx_unlock(&vm_object_list_mtx); 1732 1733 if (sp->sw_used) { 1734 /* 1735 * Objects may be locked or paging to the device being 1736 * removed, so we will miss their pages and need to 1737 * make another pass. We have marked this device as 1738 * SW_CLOSING, so the activity should finish soon. 1739 */ 1740 retries++; 1741 if (retries > 100) { 1742 panic("swapoff: failed to locate %d swap blocks", 1743 sp->sw_used); 1744 } 1745 pause("swpoff", hz / 20); 1746 goto full_rescan; 1747 } 1748 EVENTHANDLER_INVOKE(swapoff, sp); 1749 } 1750 1751 /************************************************************************ 1752 * SWAP META DATA * 1753 ************************************************************************ 1754 * 1755 * These routines manipulate the swap metadata stored in the 1756 * OBJT_SWAP object. 1757 * 1758 * Swap metadata is implemented with a global hash and not directly 1759 * linked into the object. Instead the object simply contains 1760 * appropriate tracking counters. 1761 */ 1762 1763 /* 1764 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1765 * 1766 * We first convert the object to a swap object if it is a default 1767 * object. 1768 * 1769 * The specified swapblk is added to the object's swap metadata. If 1770 * the swapblk is not valid, it is freed instead. Any previously 1771 * assigned swapblk is freed. 1772 */ 1773 static void 1774 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1775 { 1776 static volatile int swblk_zone_exhausted, swpctrie_zone_exhausted; 1777 struct swblk *sb, *sb1; 1778 vm_pindex_t modpi, rdpi; 1779 int error, i; 1780 1781 VM_OBJECT_ASSERT_WLOCKED(object); 1782 1783 /* 1784 * Convert default object to swap object if necessary 1785 */ 1786 if (object->type != OBJT_SWAP) { 1787 pctrie_init(&object->un_pager.swp.swp_blks); 1788 1789 /* 1790 * Ensure that swap_pager_swapoff()'s iteration over 1791 * object_list does not see a garbage pctrie. 1792 */ 1793 atomic_thread_fence_rel(); 1794 1795 object->type = OBJT_SWAP; 1796 KASSERT(object->handle == NULL, ("default pager with handle")); 1797 } 1798 1799 rdpi = rounddown(pindex, SWAP_META_PAGES); 1800 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, rdpi); 1801 if (sb == NULL) { 1802 if (swapblk == SWAPBLK_NONE) 1803 return; 1804 for (;;) { 1805 sb = uma_zalloc(swblk_zone, M_NOWAIT | (curproc == 1806 pageproc ? M_USE_RESERVE : 0)); 1807 if (sb != NULL) { 1808 sb->p = rdpi; 1809 for (i = 0; i < SWAP_META_PAGES; i++) 1810 sb->d[i] = SWAPBLK_NONE; 1811 if (atomic_cmpset_int(&swblk_zone_exhausted, 1812 1, 0)) 1813 printf("swblk zone ok\n"); 1814 break; 1815 } 1816 VM_OBJECT_WUNLOCK(object); 1817 if (uma_zone_exhausted(swblk_zone)) { 1818 if (atomic_cmpset_int(&swblk_zone_exhausted, 1819 0, 1)) 1820 printf("swap blk zone exhausted, " 1821 "increase kern.maxswzone\n"); 1822 vm_pageout_oom(VM_OOM_SWAPZ); 1823 pause("swzonxb", 10); 1824 } else 1825 uma_zwait(swblk_zone); 1826 VM_OBJECT_WLOCK(object); 1827 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 1828 rdpi); 1829 if (sb != NULL) 1830 /* 1831 * Somebody swapped out a nearby page, 1832 * allocating swblk at the rdpi index, 1833 * while we dropped the object lock. 1834 */ 1835 goto allocated; 1836 } 1837 for (;;) { 1838 error = SWAP_PCTRIE_INSERT( 1839 &object->un_pager.swp.swp_blks, sb); 1840 if (error == 0) { 1841 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1842 1, 0)) 1843 printf("swpctrie zone ok\n"); 1844 break; 1845 } 1846 VM_OBJECT_WUNLOCK(object); 1847 if (uma_zone_exhausted(swpctrie_zone)) { 1848 if (atomic_cmpset_int(&swpctrie_zone_exhausted, 1849 0, 1)) 1850 printf("swap pctrie zone exhausted, " 1851 "increase kern.maxswzone\n"); 1852 vm_pageout_oom(VM_OOM_SWAPZ); 1853 pause("swzonxp", 10); 1854 } else 1855 uma_zwait(swpctrie_zone); 1856 VM_OBJECT_WLOCK(object); 1857 sb1 = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 1858 rdpi); 1859 if (sb1 != NULL) { 1860 uma_zfree(swblk_zone, sb); 1861 sb = sb1; 1862 goto allocated; 1863 } 1864 } 1865 } 1866 allocated: 1867 MPASS(sb->p == rdpi); 1868 1869 modpi = pindex % SWAP_META_PAGES; 1870 /* Delete prior contents of metadata. */ 1871 if (sb->d[modpi] != SWAPBLK_NONE) 1872 swp_pager_freeswapspace(sb->d[modpi], 1); 1873 /* Enter block into metadata. */ 1874 sb->d[modpi] = swapblk; 1875 1876 /* 1877 * Free the swblk if we end up with the empty page run. 1878 */ 1879 if (swapblk == SWAPBLK_NONE) { 1880 for (i = 0; i < SWAP_META_PAGES; i++) { 1881 if (sb->d[i] != SWAPBLK_NONE) 1882 break; 1883 } 1884 if (i == SWAP_META_PAGES) { 1885 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, 1886 rdpi); 1887 uma_zfree(swblk_zone, sb); 1888 } 1889 } 1890 } 1891 1892 /* 1893 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 1894 * 1895 * The requested range of blocks is freed, with any associated swap 1896 * returned to the swap bitmap. 1897 * 1898 * This routine will free swap metadata structures as they are cleaned 1899 * out. This routine does *NOT* operate on swap metadata associated 1900 * with resident pages. 1901 */ 1902 static void 1903 swp_pager_meta_free(vm_object_t object, vm_pindex_t pindex, vm_pindex_t count) 1904 { 1905 struct swblk *sb; 1906 vm_pindex_t last; 1907 int i; 1908 bool empty; 1909 1910 VM_OBJECT_ASSERT_WLOCKED(object); 1911 if (object->type != OBJT_SWAP || count == 0) 1912 return; 1913 1914 last = pindex + count - 1; 1915 for (;;) { 1916 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 1917 rounddown(pindex, SWAP_META_PAGES)); 1918 if (sb == NULL || sb->p > last) 1919 break; 1920 empty = true; 1921 for (i = 0; i < SWAP_META_PAGES; i++) { 1922 if (sb->d[i] == SWAPBLK_NONE) 1923 continue; 1924 if (pindex <= sb->p + i && sb->p + i <= last) { 1925 swp_pager_freeswapspace(sb->d[i], 1); 1926 sb->d[i] = SWAPBLK_NONE; 1927 } else 1928 empty = false; 1929 } 1930 pindex = sb->p + SWAP_META_PAGES; 1931 if (empty) { 1932 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, 1933 sb->p); 1934 uma_zfree(swblk_zone, sb); 1935 } 1936 } 1937 } 1938 1939 /* 1940 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 1941 * 1942 * This routine locates and destroys all swap metadata associated with 1943 * an object. 1944 */ 1945 static void 1946 swp_pager_meta_free_all(vm_object_t object) 1947 { 1948 struct swblk *sb; 1949 vm_pindex_t pindex; 1950 int i; 1951 1952 VM_OBJECT_ASSERT_WLOCKED(object); 1953 if (object->type != OBJT_SWAP) 1954 return; 1955 1956 for (pindex = 0; (sb = SWAP_PCTRIE_LOOKUP_GE( 1957 &object->un_pager.swp.swp_blks, pindex)) != NULL;) { 1958 pindex = sb->p + SWAP_META_PAGES; 1959 for (i = 0; i < SWAP_META_PAGES; i++) { 1960 if (sb->d[i] != SWAPBLK_NONE) 1961 swp_pager_freeswapspace(sb->d[i], 1); 1962 } 1963 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, sb->p); 1964 uma_zfree(swblk_zone, sb); 1965 } 1966 } 1967 1968 /* 1969 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. 1970 * 1971 * This routine is capable of looking up, popping, or freeing 1972 * swapblk assignments in the swap meta data or in the vm_page_t. 1973 * The routine typically returns the swapblk being looked-up, or popped, 1974 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block 1975 * was invalid. This routine will automatically free any invalid 1976 * meta-data swapblks. 1977 * 1978 * When acting on a busy resident page and paging is in progress, we 1979 * have to wait until paging is complete but otherwise can act on the 1980 * busy page. 1981 * 1982 * SWM_FREE remove and free swap block from metadata 1983 * SWM_POP remove from meta data but do not free.. pop it out 1984 */ 1985 static daddr_t 1986 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags) 1987 { 1988 struct swblk *sb; 1989 daddr_t r1; 1990 int i; 1991 1992 if ((flags & (SWM_FREE | SWM_POP)) != 0) 1993 VM_OBJECT_ASSERT_WLOCKED(object); 1994 else 1995 VM_OBJECT_ASSERT_LOCKED(object); 1996 1997 /* 1998 * The meta data only exists if the object is OBJT_SWAP 1999 * and even then might not be allocated yet. 2000 */ 2001 if (object->type != OBJT_SWAP) 2002 return (SWAPBLK_NONE); 2003 2004 sb = SWAP_PCTRIE_LOOKUP(&object->un_pager.swp.swp_blks, 2005 rounddown(pindex, SWAP_META_PAGES)); 2006 if (sb == NULL) 2007 return (SWAPBLK_NONE); 2008 r1 = sb->d[pindex % SWAP_META_PAGES]; 2009 if (r1 == SWAPBLK_NONE) 2010 return (SWAPBLK_NONE); 2011 if ((flags & (SWM_FREE | SWM_POP)) != 0) { 2012 sb->d[pindex % SWAP_META_PAGES] = SWAPBLK_NONE; 2013 for (i = 0; i < SWAP_META_PAGES; i++) { 2014 if (sb->d[i] != SWAPBLK_NONE) 2015 break; 2016 } 2017 if (i == SWAP_META_PAGES) { 2018 SWAP_PCTRIE_REMOVE(&object->un_pager.swp.swp_blks, 2019 rounddown(pindex, SWAP_META_PAGES)); 2020 uma_zfree(swblk_zone, sb); 2021 } 2022 } 2023 if ((flags & SWM_FREE) != 0) { 2024 swp_pager_freeswapspace(r1, 1); 2025 r1 = SWAPBLK_NONE; 2026 } 2027 return (r1); 2028 } 2029 2030 /* 2031 * Returns the least page index which is greater than or equal to the 2032 * parameter pindex and for which there is a swap block allocated. 2033 * Returns object's size if the object's type is not swap or if there 2034 * are no allocated swap blocks for the object after the requested 2035 * pindex. 2036 */ 2037 vm_pindex_t 2038 swap_pager_find_least(vm_object_t object, vm_pindex_t pindex) 2039 { 2040 struct swblk *sb; 2041 int i; 2042 2043 VM_OBJECT_ASSERT_LOCKED(object); 2044 if (object->type != OBJT_SWAP) 2045 return (object->size); 2046 2047 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2048 rounddown(pindex, SWAP_META_PAGES)); 2049 if (sb == NULL) 2050 return (object->size); 2051 if (sb->p < pindex) { 2052 for (i = pindex % SWAP_META_PAGES; i < SWAP_META_PAGES; i++) { 2053 if (sb->d[i] != SWAPBLK_NONE) 2054 return (sb->p + i); 2055 } 2056 sb = SWAP_PCTRIE_LOOKUP_GE(&object->un_pager.swp.swp_blks, 2057 roundup(pindex, SWAP_META_PAGES)); 2058 if (sb == NULL) 2059 return (object->size); 2060 } 2061 for (i = 0; i < SWAP_META_PAGES; i++) { 2062 if (sb->d[i] != SWAPBLK_NONE) 2063 return (sb->p + i); 2064 } 2065 2066 /* 2067 * We get here if a swblk is present in the trie but it 2068 * doesn't map any blocks. 2069 */ 2070 MPASS(0); 2071 return (object->size); 2072 } 2073 2074 /* 2075 * System call swapon(name) enables swapping on device name, 2076 * which must be in the swdevsw. Return EBUSY 2077 * if already swapping on this device. 2078 */ 2079 #ifndef _SYS_SYSPROTO_H_ 2080 struct swapon_args { 2081 char *name; 2082 }; 2083 #endif 2084 2085 /* 2086 * MPSAFE 2087 */ 2088 /* ARGSUSED */ 2089 int 2090 sys_swapon(struct thread *td, struct swapon_args *uap) 2091 { 2092 struct vattr attr; 2093 struct vnode *vp; 2094 struct nameidata nd; 2095 int error; 2096 2097 error = priv_check(td, PRIV_SWAPON); 2098 if (error) 2099 return (error); 2100 2101 sx_xlock(&swdev_syscall_lock); 2102 2103 /* 2104 * Swap metadata may not fit in the KVM if we have physical 2105 * memory of >1GB. 2106 */ 2107 if (swblk_zone == NULL) { 2108 error = ENOMEM; 2109 goto done; 2110 } 2111 2112 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW | AUDITVNODE1, UIO_USERSPACE, 2113 uap->name, td); 2114 error = namei(&nd); 2115 if (error) 2116 goto done; 2117 2118 NDFREE(&nd, NDF_ONLY_PNBUF); 2119 vp = nd.ni_vp; 2120 2121 if (vn_isdisk(vp, &error)) { 2122 error = swapongeom(vp); 2123 } else if (vp->v_type == VREG && 2124 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2125 (error = VOP_GETATTR(vp, &attr, td->td_ucred)) == 0) { 2126 /* 2127 * Allow direct swapping to NFS regular files in the same 2128 * way that nfs_mountroot() sets up diskless swapping. 2129 */ 2130 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2131 } 2132 2133 if (error) 2134 vrele(vp); 2135 done: 2136 sx_xunlock(&swdev_syscall_lock); 2137 return (error); 2138 } 2139 2140 /* 2141 * Check that the total amount of swap currently configured does not 2142 * exceed half the theoretical maximum. If it does, print a warning 2143 * message. 2144 */ 2145 static void 2146 swapon_check_swzone(void) 2147 { 2148 unsigned long maxpages, npages; 2149 2150 npages = swap_total / PAGE_SIZE; 2151 /* absolute maximum we can handle assuming 100% efficiency */ 2152 maxpages = uma_zone_get_max(swblk_zone) * SWAP_META_PAGES; 2153 2154 /* recommend using no more than half that amount */ 2155 if (npages > maxpages / 2) { 2156 printf("warning: total configured swap (%lu pages) " 2157 "exceeds maximum recommended amount (%lu pages).\n", 2158 npages, maxpages / 2); 2159 printf("warning: increase kern.maxswzone " 2160 "or reduce amount of swap.\n"); 2161 } 2162 } 2163 2164 static void 2165 swaponsomething(struct vnode *vp, void *id, u_long nblks, 2166 sw_strategy_t *strategy, sw_close_t *close, dev_t dev, int flags) 2167 { 2168 struct swdevt *sp, *tsp; 2169 swblk_t dvbase; 2170 u_long mblocks; 2171 2172 /* 2173 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2174 * First chop nblks off to page-align it, then convert. 2175 * 2176 * sw->sw_nblks is in page-sized chunks now too. 2177 */ 2178 nblks &= ~(ctodb(1) - 1); 2179 nblks = dbtoc(nblks); 2180 2181 /* 2182 * If we go beyond this, we get overflows in the radix 2183 * tree bitmap code. 2184 */ 2185 mblocks = 0x40000000 / BLIST_META_RADIX; 2186 if (nblks > mblocks) { 2187 printf( 2188 "WARNING: reducing swap size to maximum of %luMB per unit\n", 2189 mblocks / 1024 / 1024 * PAGE_SIZE); 2190 nblks = mblocks; 2191 } 2192 2193 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2194 sp->sw_vp = vp; 2195 sp->sw_id = id; 2196 sp->sw_dev = dev; 2197 sp->sw_flags = 0; 2198 sp->sw_nblks = nblks; 2199 sp->sw_used = 0; 2200 sp->sw_strategy = strategy; 2201 sp->sw_close = close; 2202 sp->sw_flags = flags; 2203 2204 sp->sw_blist = blist_create(nblks, M_WAITOK); 2205 /* 2206 * Do not free the first two block in order to avoid overwriting 2207 * any bsd label at the front of the partition 2208 */ 2209 blist_free(sp->sw_blist, 2, nblks - 2); 2210 2211 dvbase = 0; 2212 mtx_lock(&sw_dev_mtx); 2213 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2214 if (tsp->sw_end >= dvbase) { 2215 /* 2216 * We put one uncovered page between the devices 2217 * in order to definitively prevent any cross-device 2218 * I/O requests 2219 */ 2220 dvbase = tsp->sw_end + 1; 2221 } 2222 } 2223 sp->sw_first = dvbase; 2224 sp->sw_end = dvbase + nblks; 2225 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2226 nswapdev++; 2227 swap_pager_avail += nblks - 2; 2228 swap_total += (vm_ooffset_t)nblks * PAGE_SIZE; 2229 swapon_check_swzone(); 2230 swp_sizecheck(); 2231 mtx_unlock(&sw_dev_mtx); 2232 EVENTHANDLER_INVOKE(swapon, sp); 2233 } 2234 2235 /* 2236 * SYSCALL: swapoff(devname) 2237 * 2238 * Disable swapping on the given device. 2239 * 2240 * XXX: Badly designed system call: it should use a device index 2241 * rather than filename as specification. We keep sw_vp around 2242 * only to make this work. 2243 */ 2244 #ifndef _SYS_SYSPROTO_H_ 2245 struct swapoff_args { 2246 char *name; 2247 }; 2248 #endif 2249 2250 /* 2251 * MPSAFE 2252 */ 2253 /* ARGSUSED */ 2254 int 2255 sys_swapoff(struct thread *td, struct swapoff_args *uap) 2256 { 2257 struct vnode *vp; 2258 struct nameidata nd; 2259 struct swdevt *sp; 2260 int error; 2261 2262 error = priv_check(td, PRIV_SWAPOFF); 2263 if (error) 2264 return (error); 2265 2266 sx_xlock(&swdev_syscall_lock); 2267 2268 NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->name, 2269 td); 2270 error = namei(&nd); 2271 if (error) 2272 goto done; 2273 NDFREE(&nd, NDF_ONLY_PNBUF); 2274 vp = nd.ni_vp; 2275 2276 mtx_lock(&sw_dev_mtx); 2277 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2278 if (sp->sw_vp == vp) 2279 break; 2280 } 2281 mtx_unlock(&sw_dev_mtx); 2282 if (sp == NULL) { 2283 error = EINVAL; 2284 goto done; 2285 } 2286 error = swapoff_one(sp, td->td_ucred); 2287 done: 2288 sx_xunlock(&swdev_syscall_lock); 2289 return (error); 2290 } 2291 2292 static int 2293 swapoff_one(struct swdevt *sp, struct ucred *cred) 2294 { 2295 u_long nblks; 2296 #ifdef MAC 2297 int error; 2298 #endif 2299 2300 sx_assert(&swdev_syscall_lock, SA_XLOCKED); 2301 #ifdef MAC 2302 (void) vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 2303 error = mac_system_check_swapoff(cred, sp->sw_vp); 2304 (void) VOP_UNLOCK(sp->sw_vp, 0); 2305 if (error != 0) 2306 return (error); 2307 #endif 2308 nblks = sp->sw_nblks; 2309 2310 /* 2311 * We can turn off this swap device safely only if the 2312 * available virtual memory in the system will fit the amount 2313 * of data we will have to page back in, plus an epsilon so 2314 * the system doesn't become critically low on swap space. 2315 */ 2316 if (vm_cnt.v_free_count + swap_pager_avail < nblks + nswap_lowat) 2317 return (ENOMEM); 2318 2319 /* 2320 * Prevent further allocations on this device. 2321 */ 2322 mtx_lock(&sw_dev_mtx); 2323 sp->sw_flags |= SW_CLOSING; 2324 swap_pager_avail -= blist_fill(sp->sw_blist, 0, nblks); 2325 swap_total -= (vm_ooffset_t)nblks * PAGE_SIZE; 2326 mtx_unlock(&sw_dev_mtx); 2327 2328 /* 2329 * Page in the contents of the device and close it. 2330 */ 2331 swap_pager_swapoff(sp); 2332 2333 sp->sw_close(curthread, sp); 2334 mtx_lock(&sw_dev_mtx); 2335 sp->sw_id = NULL; 2336 TAILQ_REMOVE(&swtailq, sp, sw_list); 2337 nswapdev--; 2338 if (nswapdev == 0) { 2339 swap_pager_full = 2; 2340 swap_pager_almost_full = 1; 2341 } 2342 if (swdevhd == sp) 2343 swdevhd = NULL; 2344 mtx_unlock(&sw_dev_mtx); 2345 blist_destroy(sp->sw_blist); 2346 free(sp, M_VMPGDATA); 2347 return (0); 2348 } 2349 2350 void 2351 swapoff_all(void) 2352 { 2353 struct swdevt *sp, *spt; 2354 const char *devname; 2355 int error; 2356 2357 sx_xlock(&swdev_syscall_lock); 2358 2359 mtx_lock(&sw_dev_mtx); 2360 TAILQ_FOREACH_SAFE(sp, &swtailq, sw_list, spt) { 2361 mtx_unlock(&sw_dev_mtx); 2362 if (vn_isdisk(sp->sw_vp, NULL)) 2363 devname = devtoname(sp->sw_vp->v_rdev); 2364 else 2365 devname = "[file]"; 2366 error = swapoff_one(sp, thread0.td_ucred); 2367 if (error != 0) { 2368 printf("Cannot remove swap device %s (error=%d), " 2369 "skipping.\n", devname, error); 2370 } else if (bootverbose) { 2371 printf("Swap device %s removed.\n", devname); 2372 } 2373 mtx_lock(&sw_dev_mtx); 2374 } 2375 mtx_unlock(&sw_dev_mtx); 2376 2377 sx_xunlock(&swdev_syscall_lock); 2378 } 2379 2380 void 2381 swap_pager_status(int *total, int *used) 2382 { 2383 struct swdevt *sp; 2384 2385 *total = 0; 2386 *used = 0; 2387 mtx_lock(&sw_dev_mtx); 2388 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2389 *total += sp->sw_nblks; 2390 *used += sp->sw_used; 2391 } 2392 mtx_unlock(&sw_dev_mtx); 2393 } 2394 2395 int 2396 swap_dev_info(int name, struct xswdev *xs, char *devname, size_t len) 2397 { 2398 struct swdevt *sp; 2399 const char *tmp_devname; 2400 int error, n; 2401 2402 n = 0; 2403 error = ENOENT; 2404 mtx_lock(&sw_dev_mtx); 2405 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2406 if (n != name) { 2407 n++; 2408 continue; 2409 } 2410 xs->xsw_version = XSWDEV_VERSION; 2411 xs->xsw_dev = sp->sw_dev; 2412 xs->xsw_flags = sp->sw_flags; 2413 xs->xsw_nblks = sp->sw_nblks; 2414 xs->xsw_used = sp->sw_used; 2415 if (devname != NULL) { 2416 if (vn_isdisk(sp->sw_vp, NULL)) 2417 tmp_devname = devtoname(sp->sw_vp->v_rdev); 2418 else 2419 tmp_devname = "[file]"; 2420 strncpy(devname, tmp_devname, len); 2421 } 2422 error = 0; 2423 break; 2424 } 2425 mtx_unlock(&sw_dev_mtx); 2426 return (error); 2427 } 2428 2429 #if defined(COMPAT_FREEBSD11) 2430 #define XSWDEV_VERSION_11 1 2431 struct xswdev11 { 2432 u_int xsw_version; 2433 uint32_t xsw_dev; 2434 int xsw_flags; 2435 int xsw_nblks; 2436 int xsw_used; 2437 }; 2438 #endif 2439 2440 static int 2441 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2442 { 2443 struct xswdev xs; 2444 #if defined(COMPAT_FREEBSD11) 2445 struct xswdev11 xs11; 2446 #endif 2447 int error; 2448 2449 if (arg2 != 1) /* name length */ 2450 return (EINVAL); 2451 error = swap_dev_info(*(int *)arg1, &xs, NULL, 0); 2452 if (error != 0) 2453 return (error); 2454 #if defined(COMPAT_FREEBSD11) 2455 if (req->oldlen == sizeof(xs11)) { 2456 xs11.xsw_version = XSWDEV_VERSION_11; 2457 xs11.xsw_dev = xs.xsw_dev; /* truncation */ 2458 xs11.xsw_flags = xs.xsw_flags; 2459 xs11.xsw_nblks = xs.xsw_nblks; 2460 xs11.xsw_used = xs.xsw_used; 2461 error = SYSCTL_OUT(req, &xs11, sizeof(xs11)); 2462 } else 2463 #endif 2464 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2465 return (error); 2466 } 2467 2468 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2469 "Number of swap devices"); 2470 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD | CTLFLAG_MPSAFE, 2471 sysctl_vm_swap_info, 2472 "Swap statistics by device"); 2473 2474 /* 2475 * Count the approximate swap usage in pages for a vmspace. The 2476 * shadowed or not yet copied on write swap blocks are not accounted. 2477 * The map must be locked. 2478 */ 2479 long 2480 vmspace_swap_count(struct vmspace *vmspace) 2481 { 2482 vm_map_t map; 2483 vm_map_entry_t cur; 2484 vm_object_t object; 2485 struct swblk *sb; 2486 vm_pindex_t e, pi; 2487 long count; 2488 int i; 2489 2490 map = &vmspace->vm_map; 2491 count = 0; 2492 2493 for (cur = map->header.next; cur != &map->header; cur = cur->next) { 2494 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) 2495 continue; 2496 object = cur->object.vm_object; 2497 if (object == NULL || object->type != OBJT_SWAP) 2498 continue; 2499 VM_OBJECT_RLOCK(object); 2500 if (object->type != OBJT_SWAP) 2501 goto unlock; 2502 pi = OFF_TO_IDX(cur->offset); 2503 e = pi + OFF_TO_IDX(cur->end - cur->start); 2504 for (;; pi = sb->p + SWAP_META_PAGES) { 2505 sb = SWAP_PCTRIE_LOOKUP_GE( 2506 &object->un_pager.swp.swp_blks, pi); 2507 if (sb == NULL || sb->p >= e) 2508 break; 2509 for (i = 0; i < SWAP_META_PAGES; i++) { 2510 if (sb->p + i < e && 2511 sb->d[i] != SWAPBLK_NONE) 2512 count++; 2513 } 2514 } 2515 unlock: 2516 VM_OBJECT_RUNLOCK(object); 2517 } 2518 return (count); 2519 } 2520 2521 /* 2522 * GEOM backend 2523 * 2524 * Swapping onto disk devices. 2525 * 2526 */ 2527 2528 static g_orphan_t swapgeom_orphan; 2529 2530 static struct g_class g_swap_class = { 2531 .name = "SWAP", 2532 .version = G_VERSION, 2533 .orphan = swapgeom_orphan, 2534 }; 2535 2536 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2537 2538 2539 static void 2540 swapgeom_close_ev(void *arg, int flags) 2541 { 2542 struct g_consumer *cp; 2543 2544 cp = arg; 2545 g_access(cp, -1, -1, 0); 2546 g_detach(cp); 2547 g_destroy_consumer(cp); 2548 } 2549 2550 /* 2551 * Add a reference to the g_consumer for an inflight transaction. 2552 */ 2553 static void 2554 swapgeom_acquire(struct g_consumer *cp) 2555 { 2556 2557 mtx_assert(&sw_dev_mtx, MA_OWNED); 2558 cp->index++; 2559 } 2560 2561 /* 2562 * Remove a reference from the g_consumer. Post a close event if all 2563 * references go away, since the function might be called from the 2564 * biodone context. 2565 */ 2566 static void 2567 swapgeom_release(struct g_consumer *cp, struct swdevt *sp) 2568 { 2569 2570 mtx_assert(&sw_dev_mtx, MA_OWNED); 2571 cp->index--; 2572 if (cp->index == 0) { 2573 if (g_post_event(swapgeom_close_ev, cp, M_NOWAIT, NULL) == 0) 2574 sp->sw_id = NULL; 2575 } 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 sp = bp2->bio_caller1; 2594 mtx_lock(&sw_dev_mtx); 2595 swapgeom_release(cp, sp); 2596 mtx_unlock(&sw_dev_mtx); 2597 g_destroy_bio(bp2); 2598 } 2599 2600 static void 2601 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2602 { 2603 struct bio *bio; 2604 struct g_consumer *cp; 2605 2606 mtx_lock(&sw_dev_mtx); 2607 cp = sp->sw_id; 2608 if (cp == NULL) { 2609 mtx_unlock(&sw_dev_mtx); 2610 bp->b_error = ENXIO; 2611 bp->b_ioflags |= BIO_ERROR; 2612 bufdone(bp); 2613 return; 2614 } 2615 swapgeom_acquire(cp); 2616 mtx_unlock(&sw_dev_mtx); 2617 if (bp->b_iocmd == BIO_WRITE) 2618 bio = g_new_bio(); 2619 else 2620 bio = g_alloc_bio(); 2621 if (bio == NULL) { 2622 mtx_lock(&sw_dev_mtx); 2623 swapgeom_release(cp, sp); 2624 mtx_unlock(&sw_dev_mtx); 2625 bp->b_error = ENOMEM; 2626 bp->b_ioflags |= BIO_ERROR; 2627 bufdone(bp); 2628 return; 2629 } 2630 2631 bio->bio_caller1 = sp; 2632 bio->bio_caller2 = bp; 2633 bio->bio_cmd = bp->b_iocmd; 2634 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2635 bio->bio_length = bp->b_bcount; 2636 bio->bio_done = swapgeom_done; 2637 if (!buf_mapped(bp)) { 2638 bio->bio_ma = bp->b_pages; 2639 bio->bio_data = unmapped_buf; 2640 bio->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 2641 bio->bio_ma_n = bp->b_npages; 2642 bio->bio_flags |= BIO_UNMAPPED; 2643 } else { 2644 bio->bio_data = bp->b_data; 2645 bio->bio_ma = NULL; 2646 } 2647 g_io_request(bio, cp); 2648 return; 2649 } 2650 2651 static void 2652 swapgeom_orphan(struct g_consumer *cp) 2653 { 2654 struct swdevt *sp; 2655 int destroy; 2656 2657 mtx_lock(&sw_dev_mtx); 2658 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2659 if (sp->sw_id == cp) { 2660 sp->sw_flags |= SW_CLOSING; 2661 break; 2662 } 2663 } 2664 /* 2665 * Drop reference we were created with. Do directly since we're in a 2666 * special context where we don't have to queue the call to 2667 * swapgeom_close_ev(). 2668 */ 2669 cp->index--; 2670 destroy = ((sp != NULL) && (cp->index == 0)); 2671 if (destroy) 2672 sp->sw_id = NULL; 2673 mtx_unlock(&sw_dev_mtx); 2674 if (destroy) 2675 swapgeom_close_ev(cp, 0); 2676 } 2677 2678 static void 2679 swapgeom_close(struct thread *td, struct swdevt *sw) 2680 { 2681 struct g_consumer *cp; 2682 2683 mtx_lock(&sw_dev_mtx); 2684 cp = sw->sw_id; 2685 sw->sw_id = NULL; 2686 mtx_unlock(&sw_dev_mtx); 2687 2688 /* 2689 * swapgeom_close() may be called from the biodone context, 2690 * where we cannot perform topology changes. Delegate the 2691 * work to the events thread. 2692 */ 2693 if (cp != NULL) 2694 g_waitfor_event(swapgeom_close_ev, cp, M_WAITOK, NULL); 2695 } 2696 2697 static int 2698 swapongeom_locked(struct cdev *dev, struct vnode *vp) 2699 { 2700 struct g_provider *pp; 2701 struct g_consumer *cp; 2702 static struct g_geom *gp; 2703 struct swdevt *sp; 2704 u_long nblks; 2705 int error; 2706 2707 pp = g_dev_getprovider(dev); 2708 if (pp == NULL) 2709 return (ENODEV); 2710 mtx_lock(&sw_dev_mtx); 2711 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2712 cp = sp->sw_id; 2713 if (cp != NULL && cp->provider == pp) { 2714 mtx_unlock(&sw_dev_mtx); 2715 return (EBUSY); 2716 } 2717 } 2718 mtx_unlock(&sw_dev_mtx); 2719 if (gp == NULL) 2720 gp = g_new_geomf(&g_swap_class, "swap"); 2721 cp = g_new_consumer(gp); 2722 cp->index = 1; /* Number of active I/Os, plus one for being active. */ 2723 cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE; 2724 g_attach(cp, pp); 2725 /* 2726 * XXX: Every time you think you can improve the margin for 2727 * footshooting, somebody depends on the ability to do so: 2728 * savecore(8) wants to write to our swapdev so we cannot 2729 * set an exclusive count :-( 2730 */ 2731 error = g_access(cp, 1, 1, 0); 2732 if (error != 0) { 2733 g_detach(cp); 2734 g_destroy_consumer(cp); 2735 return (error); 2736 } 2737 nblks = pp->mediasize / DEV_BSIZE; 2738 swaponsomething(vp, cp, nblks, swapgeom_strategy, 2739 swapgeom_close, dev2udev(dev), 2740 (pp->flags & G_PF_ACCEPT_UNMAPPED) != 0 ? SW_UNMAPPED : 0); 2741 return (0); 2742 } 2743 2744 static int 2745 swapongeom(struct vnode *vp) 2746 { 2747 int error; 2748 2749 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2750 if (vp->v_type != VCHR || (vp->v_iflag & VI_DOOMED) != 0) { 2751 error = ENOENT; 2752 } else { 2753 g_topology_lock(); 2754 error = swapongeom_locked(vp->v_rdev, vp); 2755 g_topology_unlock(); 2756 } 2757 VOP_UNLOCK(vp, 0); 2758 return (error); 2759 } 2760 2761 /* 2762 * VNODE backend 2763 * 2764 * This is used mainly for network filesystem (read: probably only tested 2765 * with NFS) swapfiles. 2766 * 2767 */ 2768 2769 static void 2770 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2771 { 2772 struct vnode *vp2; 2773 2774 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2775 2776 vp2 = sp->sw_id; 2777 vhold(vp2); 2778 if (bp->b_iocmd == BIO_WRITE) { 2779 if (bp->b_bufobj) 2780 bufobj_wdrop(bp->b_bufobj); 2781 bufobj_wref(&vp2->v_bufobj); 2782 } 2783 if (bp->b_bufobj != &vp2->v_bufobj) 2784 bp->b_bufobj = &vp2->v_bufobj; 2785 bp->b_vp = vp2; 2786 bp->b_iooffset = dbtob(bp->b_blkno); 2787 bstrategy(bp); 2788 return; 2789 } 2790 2791 static void 2792 swapdev_close(struct thread *td, struct swdevt *sp) 2793 { 2794 2795 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2796 vrele(sp->sw_vp); 2797 } 2798 2799 2800 static int 2801 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2802 { 2803 struct swdevt *sp; 2804 int error; 2805 2806 if (nblks == 0) 2807 return (ENXIO); 2808 mtx_lock(&sw_dev_mtx); 2809 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2810 if (sp->sw_id == vp) { 2811 mtx_unlock(&sw_dev_mtx); 2812 return (EBUSY); 2813 } 2814 } 2815 mtx_unlock(&sw_dev_mtx); 2816 2817 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 2818 #ifdef MAC 2819 error = mac_system_check_swapon(td->td_ucred, vp); 2820 if (error == 0) 2821 #endif 2822 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, NULL); 2823 (void) VOP_UNLOCK(vp, 0); 2824 if (error) 2825 return (error); 2826 2827 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 2828 NODEV, 0); 2829 return (0); 2830 } 2831 2832 static int 2833 sysctl_swap_async_max(SYSCTL_HANDLER_ARGS) 2834 { 2835 int error, new, n; 2836 2837 new = nsw_wcount_async_max; 2838 error = sysctl_handle_int(oidp, &new, 0, req); 2839 if (error != 0 || req->newptr == NULL) 2840 return (error); 2841 2842 if (new > nswbuf / 2 || new < 1) 2843 return (EINVAL); 2844 2845 mtx_lock(&pbuf_mtx); 2846 while (nsw_wcount_async_max != new) { 2847 /* 2848 * Adjust difference. If the current async count is too low, 2849 * we will need to sqeeze our update slowly in. Sleep with a 2850 * higher priority than getpbuf() to finish faster. 2851 */ 2852 n = new - nsw_wcount_async_max; 2853 if (nsw_wcount_async + n >= 0) { 2854 nsw_wcount_async += n; 2855 nsw_wcount_async_max += n; 2856 wakeup(&nsw_wcount_async); 2857 } else { 2858 nsw_wcount_async_max -= nsw_wcount_async; 2859 nsw_wcount_async = 0; 2860 msleep(&nsw_wcount_async, &pbuf_mtx, PSWP, 2861 "swpsysctl", 0); 2862 } 2863 } 2864 mtx_unlock(&pbuf_mtx); 2865 2866 return (0); 2867 } 2868