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_mac.h" 73 #include "opt_swap.h" 74 #include "opt_vm.h" 75 76 #include <sys/param.h> 77 #include <sys/systm.h> 78 #include <sys/conf.h> 79 #include <sys/kernel.h> 80 #include <sys/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/mac.h> 89 #include <sys/malloc.h> 90 #include <sys/sysctl.h> 91 #include <sys/sysproto.h> 92 #include <sys/blist.h> 93 #include <sys/lock.h> 94 #include <sys/sx.h> 95 #include <sys/vmmeter.h> 96 97 #include <vm/vm.h> 98 #include <vm/pmap.h> 99 #include <vm/vm_map.h> 100 #include <vm/vm_kern.h> 101 #include <vm/vm_object.h> 102 #include <vm/vm_page.h> 103 #include <vm/vm_pager.h> 104 #include <vm/vm_pageout.h> 105 #include <vm/vm_param.h> 106 #include <vm/swap_pager.h> 107 #include <vm/vm_extern.h> 108 #include <vm/uma.h> 109 110 #include <geom/geom.h> 111 112 /* 113 * SWB_NPAGES must be a power of 2. It may be set to 1, 2, 4, 8, or 16 114 * pages per allocation. We recommend you stick with the default of 8. 115 * The 16-page limit is due to the radix code (kern/subr_blist.c). 116 */ 117 #ifndef MAX_PAGEOUT_CLUSTER 118 #define MAX_PAGEOUT_CLUSTER 16 119 #endif 120 121 #if !defined(SWB_NPAGES) 122 #define SWB_NPAGES MAX_PAGEOUT_CLUSTER 123 #endif 124 125 /* 126 * Piecemeal swap metadata structure. Swap is stored in a radix tree. 127 * 128 * If SWB_NPAGES is 8 and sizeof(char *) == sizeof(daddr_t), our radix 129 * is basically 8. Assuming PAGE_SIZE == 4096, one tree level represents 130 * 32K worth of data, two levels represent 256K, three levels represent 131 * 2 MBytes. This is acceptable. 132 * 133 * Overall memory utilization is about the same as the old swap structure. 134 */ 135 #define SWCORRECT(n) (sizeof(void *) * (n) / sizeof(daddr_t)) 136 #define SWAP_META_PAGES (SWB_NPAGES * 2) 137 #define SWAP_META_MASK (SWAP_META_PAGES - 1) 138 139 typedef int32_t swblk_t; /* 140 * swap offset. This is the type used to 141 * address the "virtual swap device" and 142 * therefore the maximum swap space is 143 * 2^32 pages. 144 */ 145 146 struct swdevt; 147 typedef void sw_strategy_t(struct buf *bp, struct swdevt *sw); 148 typedef void sw_close_t(struct thread *td, struct swdevt *sw); 149 150 /* 151 * Swap device table 152 */ 153 struct swdevt { 154 int sw_flags; 155 int sw_nblks; 156 int sw_used; 157 dev_t sw_dev; 158 struct vnode *sw_vp; 159 void *sw_id; 160 swblk_t sw_first; 161 swblk_t sw_end; 162 struct blist *sw_blist; 163 TAILQ_ENTRY(swdevt) sw_list; 164 sw_strategy_t *sw_strategy; 165 sw_close_t *sw_close; 166 }; 167 168 #define SW_CLOSING 0x04 169 170 struct swblock { 171 struct swblock *swb_hnext; 172 vm_object_t swb_object; 173 vm_pindex_t swb_index; 174 int swb_count; 175 daddr_t swb_pages[SWAP_META_PAGES]; 176 }; 177 178 static struct mtx sw_dev_mtx; 179 static TAILQ_HEAD(, swdevt) swtailq = TAILQ_HEAD_INITIALIZER(swtailq); 180 static struct swdevt *swdevhd; /* Allocate from here next */ 181 static int nswapdev; /* Number of swap devices */ 182 int swap_pager_avail; 183 static int swdev_syscall_active = 0; /* serialize swap(on|off) */ 184 185 static void swapdev_strategy(struct buf *, struct swdevt *sw); 186 187 #define SWM_FREE 0x02 /* free, period */ 188 #define SWM_POP 0x04 /* pop out */ 189 190 int swap_pager_full = 2; /* swap space exhaustion (task killing) */ 191 static int swap_pager_almost_full = 1; /* swap space exhaustion (w/hysteresis)*/ 192 static int nsw_rcount; /* free read buffers */ 193 static int nsw_wcount_sync; /* limit write buffers / synchronous */ 194 static int nsw_wcount_async; /* limit write buffers / asynchronous */ 195 static int nsw_wcount_async_max;/* assigned maximum */ 196 static int nsw_cluster_max; /* maximum VOP I/O allowed */ 197 198 static struct swblock **swhash; 199 static int swhash_mask; 200 static struct mtx swhash_mtx; 201 202 static int swap_async_max = 4; /* maximum in-progress async I/O's */ 203 static struct sx sw_alloc_sx; 204 205 206 SYSCTL_INT(_vm, OID_AUTO, swap_async_max, 207 CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops"); 208 209 /* 210 * "named" and "unnamed" anon region objects. Try to reduce the overhead 211 * of searching a named list by hashing it just a little. 212 */ 213 214 #define NOBJLISTS 8 215 216 #define NOBJLIST(handle) \ 217 (&swap_pager_object_list[((int)(intptr_t)handle >> 4) & (NOBJLISTS-1)]) 218 219 static struct mtx sw_alloc_mtx; /* protect list manipulation */ 220 static struct pagerlst swap_pager_object_list[NOBJLISTS]; 221 static uma_zone_t swap_zone; 222 static struct vm_object swap_zone_obj; 223 224 /* 225 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 226 * calls hooked from other parts of the VM system and do not appear here. 227 * (see vm/swap_pager.h). 228 */ 229 static vm_object_t 230 swap_pager_alloc(void *handle, vm_ooffset_t size, 231 vm_prot_t prot, vm_ooffset_t offset); 232 static void swap_pager_dealloc(vm_object_t object); 233 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int); 234 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 235 static boolean_t 236 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 237 static void swap_pager_init(void); 238 static void swap_pager_unswapped(vm_page_t); 239 static void swap_pager_swapoff(struct swdevt *sp); 240 241 struct pagerops swappagerops = { 242 .pgo_init = swap_pager_init, /* early system initialization of pager */ 243 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 244 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 245 .pgo_getpages = swap_pager_getpages, /* pagein */ 246 .pgo_putpages = swap_pager_putpages, /* pageout */ 247 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 248 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 249 }; 250 251 /* 252 * dmmax is in page-sized chunks with the new swap system. It was 253 * dev-bsized chunks in the old. dmmax is always a power of 2. 254 * 255 * swap_*() routines are externally accessible. swp_*() routines are 256 * internal. 257 */ 258 static int dmmax; 259 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 260 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 261 262 SYSCTL_INT(_vm, OID_AUTO, dmmax, 263 CTLFLAG_RD, &dmmax, 0, "Maximum size of a swap block"); 264 265 static void swp_sizecheck(void); 266 static void swp_pager_async_iodone(struct buf *bp); 267 static int swapongeom(struct thread *, struct vnode *); 268 static int swaponvp(struct thread *, struct vnode *, u_long); 269 270 /* 271 * Swap bitmap functions 272 */ 273 static void swp_pager_freeswapspace(daddr_t blk, int npages); 274 static daddr_t swp_pager_getswapspace(int npages); 275 276 /* 277 * Metadata functions 278 */ 279 static struct swblock **swp_pager_hash(vm_object_t object, vm_pindex_t index); 280 static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 281 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, daddr_t); 282 static void swp_pager_meta_free_all(vm_object_t); 283 static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 284 285 /* 286 * SWP_SIZECHECK() - update swap_pager_full indication 287 * 288 * update the swap_pager_almost_full indication and warn when we are 289 * about to run out of swap space, using lowat/hiwat hysteresis. 290 * 291 * Clear swap_pager_full ( task killing ) indication when lowat is met. 292 * 293 * No restrictions on call 294 * This routine may not block. 295 * This routine must be called at splvm() 296 */ 297 static void 298 swp_sizecheck(void) 299 { 300 301 if (swap_pager_avail < nswap_lowat) { 302 if (swap_pager_almost_full == 0) { 303 printf("swap_pager: out of swap space\n"); 304 swap_pager_almost_full = 1; 305 } 306 } else { 307 swap_pager_full = 0; 308 if (swap_pager_avail > nswap_hiwat) 309 swap_pager_almost_full = 0; 310 } 311 } 312 313 /* 314 * SWP_PAGER_HASH() - hash swap meta data 315 * 316 * This is an helper function which hashes the swapblk given 317 * the object and page index. It returns a pointer to a pointer 318 * to the object, or a pointer to a NULL pointer if it could not 319 * find a swapblk. 320 * 321 * This routine must be called at splvm(). 322 */ 323 static struct swblock ** 324 swp_pager_hash(vm_object_t object, vm_pindex_t index) 325 { 326 struct swblock **pswap; 327 struct swblock *swap; 328 329 index &= ~(vm_pindex_t)SWAP_META_MASK; 330 pswap = &swhash[(index ^ (int)(intptr_t)object) & swhash_mask]; 331 while ((swap = *pswap) != NULL) { 332 if (swap->swb_object == object && 333 swap->swb_index == index 334 ) { 335 break; 336 } 337 pswap = &swap->swb_hnext; 338 } 339 return (pswap); 340 } 341 342 /* 343 * SWAP_PAGER_INIT() - initialize the swap pager! 344 * 345 * Expected to be started from system init. NOTE: This code is run 346 * before much else so be careful what you depend on. Most of the VM 347 * system has yet to be initialized at this point. 348 */ 349 static void 350 swap_pager_init(void) 351 { 352 /* 353 * Initialize object lists 354 */ 355 int i; 356 357 for (i = 0; i < NOBJLISTS; ++i) 358 TAILQ_INIT(&swap_pager_object_list[i]); 359 mtx_init(&sw_alloc_mtx, "swap_pager list", NULL, MTX_DEF); 360 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 361 362 /* 363 * Device Stripe, in PAGE_SIZE'd blocks 364 */ 365 dmmax = SWB_NPAGES * 2; 366 } 367 368 /* 369 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 370 * 371 * Expected to be started from pageout process once, prior to entering 372 * its main loop. 373 */ 374 void 375 swap_pager_swap_init(void) 376 { 377 int n, n2; 378 379 /* 380 * Number of in-transit swap bp operations. Don't 381 * exhaust the pbufs completely. Make sure we 382 * initialize workable values (0 will work for hysteresis 383 * but it isn't very efficient). 384 * 385 * The nsw_cluster_max is constrained by the bp->b_pages[] 386 * array (MAXPHYS/PAGE_SIZE) and our locally defined 387 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 388 * constrained by the swap device interleave stripe size. 389 * 390 * Currently we hardwire nsw_wcount_async to 4. This limit is 391 * designed to prevent other I/O from having high latencies due to 392 * our pageout I/O. The value 4 works well for one or two active swap 393 * devices but is probably a little low if you have more. Even so, 394 * a higher value would probably generate only a limited improvement 395 * with three or four active swap devices since the system does not 396 * typically have to pageout at extreme bandwidths. We will want 397 * at least 2 per swap devices, and 4 is a pretty good value if you 398 * have one NFS swap device due to the command/ack latency over NFS. 399 * So it all works out pretty well. 400 */ 401 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER); 402 403 mtx_lock(&pbuf_mtx); 404 nsw_rcount = (nswbuf + 1) / 2; 405 nsw_wcount_sync = (nswbuf + 3) / 4; 406 nsw_wcount_async = 4; 407 nsw_wcount_async_max = nsw_wcount_async; 408 mtx_unlock(&pbuf_mtx); 409 410 /* 411 * Initialize our zone. Right now I'm just guessing on the number 412 * we need based on the number of pages in the system. Each swblock 413 * can hold 16 pages, so this is probably overkill. This reservation 414 * is typically limited to around 32MB by default. 415 */ 416 n = cnt.v_page_count / 2; 417 if (maxswzone && n > maxswzone / sizeof(struct swblock)) 418 n = maxswzone / sizeof(struct swblock); 419 n2 = n; 420 swap_zone = uma_zcreate("SWAPMETA", sizeof(struct swblock), NULL, NULL, 421 NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE | UMA_ZONE_VM); 422 if (swap_zone == NULL) 423 panic("failed to create swap_zone."); 424 do { 425 if (uma_zone_set_obj(swap_zone, &swap_zone_obj, n)) 426 break; 427 /* 428 * if the allocation failed, try a zone two thirds the 429 * size of the previous attempt. 430 */ 431 n -= ((n + 2) / 3); 432 } while (n > 0); 433 if (n2 != n) 434 printf("Swap zone entries reduced from %d to %d.\n", n2, n); 435 n2 = n; 436 437 /* 438 * Initialize our meta-data hash table. The swapper does not need to 439 * be quite as efficient as the VM system, so we do not use an 440 * oversized hash table. 441 * 442 * n: size of hash table, must be power of 2 443 * swhash_mask: hash table index mask 444 */ 445 for (n = 1; n < n2 / 8; n *= 2) 446 ; 447 swhash = malloc(sizeof(struct swblock *) * n, M_VMPGDATA, M_WAITOK | M_ZERO); 448 swhash_mask = n - 1; 449 mtx_init(&swhash_mtx, "swap_pager swhash", NULL, MTX_DEF); 450 } 451 452 /* 453 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 454 * its metadata structures. 455 * 456 * This routine is called from the mmap and fork code to create a new 457 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object 458 * and then converting it with swp_pager_meta_build(). 459 * 460 * This routine may block in vm_object_allocate() and create a named 461 * object lookup race, so we must interlock. We must also run at 462 * splvm() for the object lookup to handle races with interrupts, but 463 * we do not have to maintain splvm() in between the lookup and the 464 * add because (I believe) it is not possible to attempt to create 465 * a new swap object w/handle when a default object with that handle 466 * already exists. 467 * 468 * MPSAFE 469 */ 470 static vm_object_t 471 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 472 vm_ooffset_t offset) 473 { 474 vm_object_t object; 475 vm_pindex_t pindex; 476 477 pindex = OFF_TO_IDX(offset + PAGE_MASK + size); 478 479 if (handle) { 480 mtx_lock(&Giant); 481 /* 482 * Reference existing named region or allocate new one. There 483 * should not be a race here against swp_pager_meta_build() 484 * as called from vm_page_remove() in regards to the lookup 485 * of the handle. 486 */ 487 sx_xlock(&sw_alloc_sx); 488 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 489 490 if (object != NULL) { 491 vm_object_reference(object); 492 } else { 493 object = vm_object_allocate(OBJT_DEFAULT, pindex); 494 object->handle = handle; 495 496 VM_OBJECT_LOCK(object); 497 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 498 VM_OBJECT_UNLOCK(object); 499 } 500 sx_xunlock(&sw_alloc_sx); 501 mtx_unlock(&Giant); 502 } else { 503 object = vm_object_allocate(OBJT_DEFAULT, pindex); 504 505 VM_OBJECT_LOCK(object); 506 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 507 VM_OBJECT_UNLOCK(object); 508 } 509 return (object); 510 } 511 512 /* 513 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 514 * 515 * The swap backing for the object is destroyed. The code is 516 * designed such that we can reinstantiate it later, but this 517 * routine is typically called only when the entire object is 518 * about to be destroyed. 519 * 520 * This routine may block, but no longer does. 521 * 522 * The object must be locked or unreferenceable. 523 */ 524 static void 525 swap_pager_dealloc(vm_object_t object) 526 { 527 int s; 528 529 /* 530 * Remove from list right away so lookups will fail if we block for 531 * pageout completion. 532 */ 533 if (object->handle != NULL) { 534 mtx_lock(&sw_alloc_mtx); 535 TAILQ_REMOVE(NOBJLIST(object->handle), object, pager_object_list); 536 mtx_unlock(&sw_alloc_mtx); 537 } 538 539 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 540 vm_object_pip_wait(object, "swpdea"); 541 542 /* 543 * Free all remaining metadata. We only bother to free it from 544 * the swap meta data. We do not attempt to free swapblk's still 545 * associated with vm_page_t's for this object. We do not care 546 * if paging is still in progress on some objects. 547 */ 548 s = splvm(); 549 swp_pager_meta_free_all(object); 550 splx(s); 551 } 552 553 /************************************************************************ 554 * SWAP PAGER BITMAP ROUTINES * 555 ************************************************************************/ 556 557 /* 558 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 559 * 560 * Allocate swap for the requested number of pages. The starting 561 * swap block number (a page index) is returned or SWAPBLK_NONE 562 * if the allocation failed. 563 * 564 * Also has the side effect of advising that somebody made a mistake 565 * when they configured swap and didn't configure enough. 566 * 567 * Must be called at splvm() to avoid races with bitmap frees from 568 * vm_page_remove() aka swap_pager_page_removed(). 569 * 570 * This routine may not block 571 * This routine must be called at splvm(). 572 * 573 * We allocate in round-robin fashion from the configured devices. 574 */ 575 static daddr_t 576 swp_pager_getswapspace(int npages) 577 { 578 daddr_t blk; 579 struct swdevt *sp; 580 int i; 581 582 blk = SWAPBLK_NONE; 583 mtx_lock(&sw_dev_mtx); 584 sp = swdevhd; 585 for (i = 0; i < nswapdev; i++) { 586 if (sp == NULL) 587 sp = TAILQ_FIRST(&swtailq); 588 if (!(sp->sw_flags & SW_CLOSING)) { 589 blk = blist_alloc(sp->sw_blist, npages); 590 if (blk != SWAPBLK_NONE) { 591 blk += sp->sw_first; 592 sp->sw_used += npages; 593 swap_pager_avail -= npages; 594 swp_sizecheck(); 595 swdevhd = TAILQ_NEXT(sp, sw_list); 596 goto done; 597 } 598 } 599 sp = TAILQ_NEXT(sp, sw_list); 600 } 601 if (swap_pager_full != 2) { 602 printf("swap_pager_getswapspace(%d): failed\n", npages); 603 swap_pager_full = 2; 604 swap_pager_almost_full = 1; 605 } 606 swdevhd = NULL; 607 done: 608 mtx_unlock(&sw_dev_mtx); 609 return (blk); 610 } 611 612 static int 613 swp_pager_isondev(daddr_t blk, struct swdevt *sp) 614 { 615 616 return (blk >= sp->sw_first && blk < sp->sw_end); 617 } 618 619 static void 620 swp_pager_strategy(struct buf *bp) 621 { 622 struct swdevt *sp; 623 624 mtx_lock(&sw_dev_mtx); 625 TAILQ_FOREACH(sp, &swtailq, sw_list) { 626 if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) { 627 mtx_unlock(&sw_dev_mtx); 628 sp->sw_strategy(bp, sp); 629 return; 630 } 631 } 632 panic("Swapdev not found"); 633 } 634 635 636 /* 637 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 638 * 639 * This routine returns the specified swap blocks back to the bitmap. 640 * 641 * Note: This routine may not block (it could in the old swap code), 642 * and through the use of the new blist routines it does not block. 643 * 644 * We must be called at splvm() to avoid races with bitmap frees from 645 * vm_page_remove() aka swap_pager_page_removed(). 646 * 647 * This routine may not block 648 * This routine must be called at splvm(). 649 */ 650 static void 651 swp_pager_freeswapspace(daddr_t blk, int npages) 652 { 653 struct swdevt *sp; 654 655 mtx_lock(&sw_dev_mtx); 656 TAILQ_FOREACH(sp, &swtailq, sw_list) { 657 if (blk >= sp->sw_first && blk < sp->sw_end) { 658 sp->sw_used -= npages; 659 /* 660 * If we are attempting to stop swapping on 661 * this device, we don't want to mark any 662 * blocks free lest they be reused. 663 */ 664 if ((sp->sw_flags & SW_CLOSING) == 0) { 665 blist_free(sp->sw_blist, blk - sp->sw_first, 666 npages); 667 swap_pager_avail += npages; 668 swp_sizecheck(); 669 } 670 mtx_unlock(&sw_dev_mtx); 671 return; 672 } 673 } 674 panic("Swapdev not found"); 675 } 676 677 /* 678 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 679 * range within an object. 680 * 681 * This is a globally accessible routine. 682 * 683 * This routine removes swapblk assignments from swap metadata. 684 * 685 * The external callers of this routine typically have already destroyed 686 * or renamed vm_page_t's associated with this range in the object so 687 * we should be ok. 688 * 689 * This routine may be called at any spl. We up our spl to splvm temporarily 690 * in order to perform the metadata removal. 691 */ 692 void 693 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 694 { 695 int s = splvm(); 696 697 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 698 swp_pager_meta_free(object, start, size); 699 splx(s); 700 } 701 702 /* 703 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 704 * 705 * Assigns swap blocks to the specified range within the object. The 706 * swap blocks are not zerod. Any previous swap assignment is destroyed. 707 * 708 * Returns 0 on success, -1 on failure. 709 */ 710 int 711 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 712 { 713 int s; 714 int n = 0; 715 daddr_t blk = SWAPBLK_NONE; 716 vm_pindex_t beg = start; /* save start index */ 717 718 s = splvm(); 719 VM_OBJECT_LOCK(object); 720 while (size) { 721 if (n == 0) { 722 n = BLIST_MAX_ALLOC; 723 while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) { 724 n >>= 1; 725 if (n == 0) { 726 swp_pager_meta_free(object, beg, start - beg); 727 VM_OBJECT_UNLOCK(object); 728 splx(s); 729 return (-1); 730 } 731 } 732 } 733 swp_pager_meta_build(object, start, blk); 734 --size; 735 ++start; 736 ++blk; 737 --n; 738 } 739 swp_pager_meta_free(object, start, n); 740 VM_OBJECT_UNLOCK(object); 741 splx(s); 742 return (0); 743 } 744 745 /* 746 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 747 * and destroy the source. 748 * 749 * Copy any valid swapblks from the source to the destination. In 750 * cases where both the source and destination have a valid swapblk, 751 * we keep the destination's. 752 * 753 * This routine is allowed to block. It may block allocating metadata 754 * indirectly through swp_pager_meta_build() or if paging is still in 755 * progress on the source. 756 * 757 * This routine can be called at any spl 758 * 759 * XXX vm_page_collapse() kinda expects us not to block because we 760 * supposedly do not need to allocate memory, but for the moment we 761 * *may* have to get a little memory from the zone allocator, but 762 * it is taken from the interrupt memory. We should be ok. 763 * 764 * The source object contains no vm_page_t's (which is just as well) 765 * 766 * The source object is of type OBJT_SWAP. 767 * 768 * The source and destination objects must be locked or 769 * inaccessible (XXX are they ?) 770 */ 771 void 772 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 773 vm_pindex_t offset, int destroysource) 774 { 775 vm_pindex_t i; 776 int s; 777 778 VM_OBJECT_LOCK_ASSERT(srcobject, MA_OWNED); 779 VM_OBJECT_LOCK_ASSERT(dstobject, MA_OWNED); 780 781 s = splvm(); 782 /* 783 * If destroysource is set, we remove the source object from the 784 * swap_pager internal queue now. 785 */ 786 if (destroysource) { 787 if (srcobject->handle != NULL) { 788 mtx_lock(&sw_alloc_mtx); 789 TAILQ_REMOVE( 790 NOBJLIST(srcobject->handle), 791 srcobject, 792 pager_object_list 793 ); 794 mtx_unlock(&sw_alloc_mtx); 795 } 796 } 797 798 /* 799 * transfer source to destination. 800 */ 801 for (i = 0; i < dstobject->size; ++i) { 802 daddr_t dstaddr; 803 804 /* 805 * Locate (without changing) the swapblk on the destination, 806 * unless it is invalid in which case free it silently, or 807 * if the destination is a resident page, in which case the 808 * source is thrown away. 809 */ 810 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 811 812 if (dstaddr == SWAPBLK_NONE) { 813 /* 814 * Destination has no swapblk and is not resident, 815 * copy source. 816 */ 817 daddr_t srcaddr; 818 819 srcaddr = swp_pager_meta_ctl( 820 srcobject, 821 i + offset, 822 SWM_POP 823 ); 824 825 if (srcaddr != SWAPBLK_NONE) { 826 /* 827 * swp_pager_meta_build() can sleep. 828 */ 829 vm_object_pip_add(srcobject, 1); 830 VM_OBJECT_UNLOCK(srcobject); 831 vm_object_pip_add(dstobject, 1); 832 swp_pager_meta_build(dstobject, i, srcaddr); 833 vm_object_pip_wakeup(dstobject); 834 VM_OBJECT_LOCK(srcobject); 835 vm_object_pip_wakeup(srcobject); 836 } 837 } else { 838 /* 839 * Destination has valid swapblk or it is represented 840 * by a resident page. We destroy the sourceblock. 841 */ 842 843 swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE); 844 } 845 } 846 847 /* 848 * Free left over swap blocks in source. 849 * 850 * We have to revert the type to OBJT_DEFAULT so we do not accidently 851 * double-remove the object from the swap queues. 852 */ 853 if (destroysource) { 854 swp_pager_meta_free_all(srcobject); 855 /* 856 * Reverting the type is not necessary, the caller is going 857 * to destroy srcobject directly, but I'm doing it here 858 * for consistency since we've removed the object from its 859 * queues. 860 */ 861 srcobject->type = OBJT_DEFAULT; 862 } 863 splx(s); 864 } 865 866 /* 867 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 868 * the requested page. 869 * 870 * We determine whether good backing store exists for the requested 871 * page and return TRUE if it does, FALSE if it doesn't. 872 * 873 * If TRUE, we also try to determine how much valid, contiguous backing 874 * store exists before and after the requested page within a reasonable 875 * distance. We do not try to restrict it to the swap device stripe 876 * (that is handled in getpages/putpages). It probably isn't worth 877 * doing here. 878 */ 879 static boolean_t 880 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after) 881 { 882 daddr_t blk0; 883 int s; 884 885 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 886 /* 887 * do we have good backing store at the requested index ? 888 */ 889 s = splvm(); 890 blk0 = swp_pager_meta_ctl(object, pindex, 0); 891 892 if (blk0 == SWAPBLK_NONE) { 893 splx(s); 894 if (before) 895 *before = 0; 896 if (after) 897 *after = 0; 898 return (FALSE); 899 } 900 901 /* 902 * find backwards-looking contiguous good backing store 903 */ 904 if (before != NULL) { 905 int i; 906 907 for (i = 1; i < (SWB_NPAGES/2); ++i) { 908 daddr_t blk; 909 910 if (i > pindex) 911 break; 912 blk = swp_pager_meta_ctl(object, pindex - i, 0); 913 if (blk != blk0 - i) 914 break; 915 } 916 *before = (i - 1); 917 } 918 919 /* 920 * find forward-looking contiguous good backing store 921 */ 922 if (after != NULL) { 923 int i; 924 925 for (i = 1; i < (SWB_NPAGES/2); ++i) { 926 daddr_t blk; 927 928 blk = swp_pager_meta_ctl(object, pindex + i, 0); 929 if (blk != blk0 + i) 930 break; 931 } 932 *after = (i - 1); 933 } 934 splx(s); 935 return (TRUE); 936 } 937 938 /* 939 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 940 * 941 * This removes any associated swap backing store, whether valid or 942 * not, from the page. 943 * 944 * This routine is typically called when a page is made dirty, at 945 * which point any associated swap can be freed. MADV_FREE also 946 * calls us in a special-case situation 947 * 948 * NOTE!!! If the page is clean and the swap was valid, the caller 949 * should make the page dirty before calling this routine. This routine 950 * does NOT change the m->dirty status of the page. Also: MADV_FREE 951 * depends on it. 952 * 953 * This routine may not block 954 * This routine must be called at splvm() 955 */ 956 static void 957 swap_pager_unswapped(vm_page_t m) 958 { 959 960 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 961 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); 962 } 963 964 /* 965 * SWAP_PAGER_GETPAGES() - bring pages in from swap 966 * 967 * Attempt to retrieve (m, count) pages from backing store, but make 968 * sure we retrieve at least m[reqpage]. We try to load in as large 969 * a chunk surrounding m[reqpage] as is contiguous in swap and which 970 * belongs to the same object. 971 * 972 * The code is designed for asynchronous operation and 973 * immediate-notification of 'reqpage' but tends not to be 974 * used that way. Please do not optimize-out this algorithmic 975 * feature, I intend to improve on it in the future. 976 * 977 * The parent has a single vm_object_pip_add() reference prior to 978 * calling us and we should return with the same. 979 * 980 * The parent has BUSY'd the pages. We should return with 'm' 981 * left busy, but the others adjusted. 982 */ 983 static int 984 swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage) 985 { 986 struct buf *bp; 987 vm_page_t mreq; 988 int s; 989 int i; 990 int j; 991 daddr_t blk; 992 993 mreq = m[reqpage]; 994 995 KASSERT(mreq->object == object, 996 ("swap_pager_getpages: object mismatch %p/%p", 997 object, mreq->object)); 998 999 /* 1000 * Calculate range to retrieve. The pages have already been assigned 1001 * their swapblks. We require a *contiguous* range but we know it to 1002 * not span devices. If we do not supply it, bad things 1003 * happen. Note that blk, iblk & jblk can be SWAPBLK_NONE, but the 1004 * loops are set up such that the case(s) are handled implicitly. 1005 * 1006 * The swp_*() calls must be made at splvm(). vm_page_free() does 1007 * not need to be, but it will go a little faster if it is. 1008 */ 1009 s = splvm(); 1010 blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0); 1011 1012 for (i = reqpage - 1; i >= 0; --i) { 1013 daddr_t iblk; 1014 1015 iblk = swp_pager_meta_ctl(m[i]->object, m[i]->pindex, 0); 1016 if (blk != iblk + (reqpage - i)) 1017 break; 1018 } 1019 ++i; 1020 1021 for (j = reqpage + 1; j < count; ++j) { 1022 daddr_t jblk; 1023 1024 jblk = swp_pager_meta_ctl(m[j]->object, m[j]->pindex, 0); 1025 if (blk != jblk - (j - reqpage)) 1026 break; 1027 } 1028 1029 /* 1030 * free pages outside our collection range. Note: we never free 1031 * mreq, it must remain busy throughout. 1032 */ 1033 vm_page_lock_queues(); 1034 { 1035 int k; 1036 1037 for (k = 0; k < i; ++k) 1038 vm_page_free(m[k]); 1039 for (k = j; k < count; ++k) 1040 vm_page_free(m[k]); 1041 } 1042 vm_page_unlock_queues(); 1043 splx(s); 1044 1045 1046 /* 1047 * Return VM_PAGER_FAIL if we have nothing to do. Return mreq 1048 * still busy, but the others unbusied. 1049 */ 1050 if (blk == SWAPBLK_NONE) 1051 return (VM_PAGER_FAIL); 1052 1053 /* 1054 * Getpbuf() can sleep. 1055 */ 1056 VM_OBJECT_UNLOCK(object); 1057 /* 1058 * Get a swap buffer header to perform the IO 1059 */ 1060 bp = getpbuf(&nsw_rcount); 1061 bp->b_flags |= B_PAGING; 1062 1063 /* 1064 * map our page(s) into kva for input 1065 */ 1066 pmap_qenter((vm_offset_t)bp->b_data, m + i, j - i); 1067 1068 bp->b_iocmd = BIO_READ; 1069 bp->b_iodone = swp_pager_async_iodone; 1070 bp->b_rcred = crhold(thread0.td_ucred); 1071 bp->b_wcred = crhold(thread0.td_ucred); 1072 bp->b_blkno = blk - (reqpage - i); 1073 bp->b_bcount = PAGE_SIZE * (j - i); 1074 bp->b_bufsize = PAGE_SIZE * (j - i); 1075 bp->b_pager.pg_reqpage = reqpage - i; 1076 1077 VM_OBJECT_LOCK(object); 1078 vm_page_lock_queues(); 1079 { 1080 int k; 1081 1082 for (k = i; k < j; ++k) { 1083 bp->b_pages[k - i] = m[k]; 1084 vm_page_flag_set(m[k], PG_SWAPINPROG); 1085 } 1086 } 1087 vm_page_unlock_queues(); 1088 VM_OBJECT_UNLOCK(object); 1089 bp->b_npages = j - i; 1090 1091 cnt.v_swapin++; 1092 cnt.v_swappgsin += bp->b_npages; 1093 1094 /* 1095 * We still hold the lock on mreq, and our automatic completion routine 1096 * does not remove it. 1097 */ 1098 VM_OBJECT_LOCK(mreq->object); 1099 vm_object_pip_add(mreq->object, bp->b_npages); 1100 VM_OBJECT_UNLOCK(mreq->object); 1101 1102 /* 1103 * perform the I/O. NOTE!!! bp cannot be considered valid after 1104 * this point because we automatically release it on completion. 1105 * Instead, we look at the one page we are interested in which we 1106 * still hold a lock on even through the I/O completion. 1107 * 1108 * The other pages in our m[] array are also released on completion, 1109 * so we cannot assume they are valid anymore either. 1110 * 1111 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1112 */ 1113 BUF_KERNPROC(bp); 1114 swp_pager_strategy(bp); 1115 1116 /* 1117 * wait for the page we want to complete. PG_SWAPINPROG is always 1118 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1119 * is set in the meta-data. 1120 */ 1121 s = splvm(); 1122 vm_page_lock_queues(); 1123 while ((mreq->flags & PG_SWAPINPROG) != 0) { 1124 vm_page_flag_set(mreq, PG_WANTED | PG_REFERENCED); 1125 cnt.v_intrans++; 1126 if (msleep(mreq, &vm_page_queue_mtx, PSWP, "swread", hz*20)) { 1127 printf( 1128 "swap_pager: indefinite wait buffer: bufobj: %p, blkno: %jd, size: %ld\n", 1129 bp->b_bufobj, (intmax_t)bp->b_blkno, bp->b_bcount); 1130 } 1131 } 1132 vm_page_unlock_queues(); 1133 splx(s); 1134 1135 VM_OBJECT_LOCK(mreq->object); 1136 /* 1137 * mreq is left busied after completion, but all the other pages 1138 * are freed. If we had an unrecoverable read error the page will 1139 * not be valid. 1140 */ 1141 if (mreq->valid != VM_PAGE_BITS_ALL) { 1142 return (VM_PAGER_ERROR); 1143 } else { 1144 return (VM_PAGER_OK); 1145 } 1146 1147 /* 1148 * A final note: in a low swap situation, we cannot deallocate swap 1149 * and mark a page dirty here because the caller is likely to mark 1150 * the page clean when we return, causing the page to possibly revert 1151 * to all-zero's later. 1152 */ 1153 } 1154 1155 /* 1156 * swap_pager_putpages: 1157 * 1158 * Assign swap (if necessary) and initiate I/O on the specified pages. 1159 * 1160 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1161 * are automatically converted to SWAP objects. 1162 * 1163 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1164 * vm_page reservation system coupled with properly written VFS devices 1165 * should ensure that no low-memory deadlock occurs. This is an area 1166 * which needs work. 1167 * 1168 * The parent has N vm_object_pip_add() references prior to 1169 * calling us and will remove references for rtvals[] that are 1170 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1171 * completion. 1172 * 1173 * The parent has soft-busy'd the pages it passes us and will unbusy 1174 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1175 * We need to unbusy the rest on I/O completion. 1176 */ 1177 void 1178 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1179 boolean_t sync, int *rtvals) 1180 { 1181 int i; 1182 int n = 0; 1183 1184 GIANT_REQUIRED; 1185 if (count && m[0]->object != object) { 1186 panic("swap_pager_getpages: object mismatch %p/%p", 1187 object, 1188 m[0]->object 1189 ); 1190 } 1191 1192 /* 1193 * Step 1 1194 * 1195 * Turn object into OBJT_SWAP 1196 * check for bogus sysops 1197 * force sync if not pageout process 1198 */ 1199 if (object->type != OBJT_SWAP) 1200 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1201 VM_OBJECT_UNLOCK(object); 1202 1203 if (curproc != pageproc) 1204 sync = TRUE; 1205 1206 /* 1207 * Step 2 1208 * 1209 * Update nsw parameters from swap_async_max sysctl values. 1210 * Do not let the sysop crash the machine with bogus numbers. 1211 */ 1212 mtx_lock(&pbuf_mtx); 1213 if (swap_async_max != nsw_wcount_async_max) { 1214 int n; 1215 int s; 1216 1217 /* 1218 * limit range 1219 */ 1220 if ((n = swap_async_max) > nswbuf / 2) 1221 n = nswbuf / 2; 1222 if (n < 1) 1223 n = 1; 1224 swap_async_max = n; 1225 1226 /* 1227 * Adjust difference ( if possible ). If the current async 1228 * count is too low, we may not be able to make the adjustment 1229 * at this time. 1230 */ 1231 s = splvm(); 1232 n -= nsw_wcount_async_max; 1233 if (nsw_wcount_async + n >= 0) { 1234 nsw_wcount_async += n; 1235 nsw_wcount_async_max += n; 1236 wakeup(&nsw_wcount_async); 1237 } 1238 splx(s); 1239 } 1240 mtx_unlock(&pbuf_mtx); 1241 1242 /* 1243 * Step 3 1244 * 1245 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1246 * The page is left dirty until the pageout operation completes 1247 * successfully. 1248 */ 1249 for (i = 0; i < count; i += n) { 1250 int s; 1251 int j; 1252 struct buf *bp; 1253 daddr_t blk; 1254 1255 /* 1256 * Maximum I/O size is limited by a number of factors. 1257 */ 1258 n = min(BLIST_MAX_ALLOC, count - i); 1259 n = min(n, nsw_cluster_max); 1260 1261 s = splvm(); 1262 1263 /* 1264 * Get biggest block of swap we can. If we fail, fall 1265 * back and try to allocate a smaller block. Don't go 1266 * overboard trying to allocate space if it would overly 1267 * fragment swap. 1268 */ 1269 while ( 1270 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE && 1271 n > 4 1272 ) { 1273 n >>= 1; 1274 } 1275 if (blk == SWAPBLK_NONE) { 1276 for (j = 0; j < n; ++j) 1277 rtvals[i+j] = VM_PAGER_FAIL; 1278 splx(s); 1279 continue; 1280 } 1281 1282 /* 1283 * All I/O parameters have been satisfied, build the I/O 1284 * request and assign the swap space. 1285 */ 1286 if (sync == TRUE) { 1287 bp = getpbuf(&nsw_wcount_sync); 1288 } else { 1289 bp = getpbuf(&nsw_wcount_async); 1290 bp->b_flags = B_ASYNC; 1291 } 1292 bp->b_flags |= B_PAGING; 1293 bp->b_iocmd = BIO_WRITE; 1294 1295 pmap_qenter((vm_offset_t)bp->b_data, &m[i], n); 1296 1297 bp->b_rcred = crhold(thread0.td_ucred); 1298 bp->b_wcred = crhold(thread0.td_ucred); 1299 bp->b_bcount = PAGE_SIZE * n; 1300 bp->b_bufsize = PAGE_SIZE * n; 1301 bp->b_blkno = blk; 1302 1303 VM_OBJECT_LOCK(object); 1304 for (j = 0; j < n; ++j) { 1305 vm_page_t mreq = m[i+j]; 1306 1307 swp_pager_meta_build( 1308 mreq->object, 1309 mreq->pindex, 1310 blk + j 1311 ); 1312 vm_page_dirty(mreq); 1313 rtvals[i+j] = VM_PAGER_OK; 1314 1315 vm_page_lock_queues(); 1316 vm_page_flag_set(mreq, PG_SWAPINPROG); 1317 vm_page_unlock_queues(); 1318 bp->b_pages[j] = mreq; 1319 } 1320 VM_OBJECT_UNLOCK(object); 1321 bp->b_npages = n; 1322 /* 1323 * Must set dirty range for NFS to work. 1324 */ 1325 bp->b_dirtyoff = 0; 1326 bp->b_dirtyend = bp->b_bcount; 1327 1328 cnt.v_swapout++; 1329 cnt.v_swappgsout += bp->b_npages; 1330 1331 splx(s); 1332 1333 /* 1334 * asynchronous 1335 * 1336 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1337 */ 1338 if (sync == FALSE) { 1339 bp->b_iodone = swp_pager_async_iodone; 1340 BUF_KERNPROC(bp); 1341 swp_pager_strategy(bp); 1342 1343 for (j = 0; j < n; ++j) 1344 rtvals[i+j] = VM_PAGER_PEND; 1345 /* restart outter loop */ 1346 continue; 1347 } 1348 1349 /* 1350 * synchronous 1351 * 1352 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1353 */ 1354 bp->b_iodone = bdone; 1355 swp_pager_strategy(bp); 1356 1357 /* 1358 * Wait for the sync I/O to complete, then update rtvals. 1359 * We just set the rtvals[] to VM_PAGER_PEND so we can call 1360 * our async completion routine at the end, thus avoiding a 1361 * double-free. 1362 */ 1363 s = splbio(); 1364 bwait(bp, PVM, "swwrt"); 1365 for (j = 0; j < n; ++j) 1366 rtvals[i+j] = VM_PAGER_PEND; 1367 /* 1368 * Now that we are through with the bp, we can call the 1369 * normal async completion, which frees everything up. 1370 */ 1371 swp_pager_async_iodone(bp); 1372 splx(s); 1373 } 1374 VM_OBJECT_LOCK(object); 1375 } 1376 1377 /* 1378 * swp_pager_async_iodone: 1379 * 1380 * Completion routine for asynchronous reads and writes from/to swap. 1381 * Also called manually by synchronous code to finish up a bp. 1382 * 1383 * For READ operations, the pages are PG_BUSY'd. For WRITE operations, 1384 * the pages are vm_page_t->busy'd. For READ operations, we PG_BUSY 1385 * unbusy all pages except the 'main' request page. For WRITE 1386 * operations, we vm_page_t->busy'd unbusy all pages ( we can do this 1387 * because we marked them all VM_PAGER_PEND on return from putpages ). 1388 * 1389 * This routine may not block. 1390 * This routine is called at splbio() or better 1391 * 1392 * We up ourselves to splvm() as required for various vm_page related 1393 * calls. 1394 */ 1395 static void 1396 swp_pager_async_iodone(struct buf *bp) 1397 { 1398 int s; 1399 int i; 1400 vm_object_t object = NULL; 1401 1402 VM_LOCK_GIANT(); 1403 bp->b_flags |= B_DONE; 1404 1405 /* 1406 * report error 1407 */ 1408 if (bp->b_ioflags & BIO_ERROR) { 1409 printf( 1410 "swap_pager: I/O error - %s failed; blkno %ld," 1411 "size %ld, error %d\n", 1412 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1413 (long)bp->b_blkno, 1414 (long)bp->b_bcount, 1415 bp->b_error 1416 ); 1417 } 1418 1419 /* 1420 * set object, raise to splvm(). 1421 */ 1422 s = splvm(); 1423 1424 /* 1425 * remove the mapping for kernel virtual 1426 */ 1427 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1428 1429 if (bp->b_npages) { 1430 object = bp->b_pages[0]->object; 1431 VM_OBJECT_LOCK(object); 1432 } 1433 vm_page_lock_queues(); 1434 /* 1435 * cleanup pages. If an error occurs writing to swap, we are in 1436 * very serious trouble. If it happens to be a disk error, though, 1437 * we may be able to recover by reassigning the swap later on. So 1438 * in this case we remove the m->swapblk assignment for the page 1439 * but do not free it in the rlist. The errornous block(s) are thus 1440 * never reallocated as swap. Redirty the page and continue. 1441 */ 1442 for (i = 0; i < bp->b_npages; ++i) { 1443 vm_page_t m = bp->b_pages[i]; 1444 1445 vm_page_flag_clear(m, PG_SWAPINPROG); 1446 1447 if (bp->b_ioflags & BIO_ERROR) { 1448 /* 1449 * If an error occurs I'd love to throw the swapblk 1450 * away without freeing it back to swapspace, so it 1451 * can never be used again. But I can't from an 1452 * interrupt. 1453 */ 1454 if (bp->b_iocmd == BIO_READ) { 1455 /* 1456 * When reading, reqpage needs to stay 1457 * locked for the parent, but all other 1458 * pages can be freed. We still want to 1459 * wakeup the parent waiting on the page, 1460 * though. ( also: pg_reqpage can be -1 and 1461 * not match anything ). 1462 * 1463 * We have to wake specifically requested pages 1464 * up too because we cleared PG_SWAPINPROG and 1465 * someone may be waiting for that. 1466 * 1467 * NOTE: for reads, m->dirty will probably 1468 * be overridden by the original caller of 1469 * getpages so don't play cute tricks here. 1470 * 1471 * XXX IT IS NOT LEGAL TO FREE THE PAGE HERE 1472 * AS THIS MESSES WITH object->memq, and it is 1473 * not legal to mess with object->memq from an 1474 * interrupt. 1475 */ 1476 m->valid = 0; 1477 if (i != bp->b_pager.pg_reqpage) 1478 vm_page_free(m); 1479 else 1480 vm_page_flash(m); 1481 /* 1482 * If i == bp->b_pager.pg_reqpage, do not wake 1483 * the page up. The caller needs to. 1484 */ 1485 } else { 1486 /* 1487 * If a write error occurs, reactivate page 1488 * so it doesn't clog the inactive list, 1489 * then finish the I/O. 1490 */ 1491 vm_page_dirty(m); 1492 vm_page_activate(m); 1493 vm_page_io_finish(m); 1494 } 1495 } else if (bp->b_iocmd == BIO_READ) { 1496 /* 1497 * For read success, clear dirty bits. Nobody should 1498 * have this page mapped but don't take any chances, 1499 * make sure the pmap modify bits are also cleared. 1500 * 1501 * NOTE: for reads, m->dirty will probably be 1502 * overridden by the original caller of getpages so 1503 * we cannot set them in order to free the underlying 1504 * swap in a low-swap situation. I don't think we'd 1505 * want to do that anyway, but it was an optimization 1506 * that existed in the old swapper for a time before 1507 * it got ripped out due to precisely this problem. 1508 * 1509 * If not the requested page then deactivate it. 1510 * 1511 * Note that the requested page, reqpage, is left 1512 * busied, but we still have to wake it up. The 1513 * other pages are released (unbusied) by 1514 * vm_page_wakeup(). We do not set reqpage's 1515 * valid bits here, it is up to the caller. 1516 */ 1517 pmap_clear_modify(m); 1518 m->valid = VM_PAGE_BITS_ALL; 1519 vm_page_undirty(m); 1520 1521 /* 1522 * We have to wake specifically requested pages 1523 * up too because we cleared PG_SWAPINPROG and 1524 * could be waiting for it in getpages. However, 1525 * be sure to not unbusy getpages specifically 1526 * requested page - getpages expects it to be 1527 * left busy. 1528 */ 1529 if (i != bp->b_pager.pg_reqpage) { 1530 vm_page_deactivate(m); 1531 vm_page_wakeup(m); 1532 } else { 1533 vm_page_flash(m); 1534 } 1535 } else { 1536 /* 1537 * For write success, clear the modify and dirty 1538 * status, then finish the I/O ( which decrements the 1539 * busy count and possibly wakes waiter's up ). 1540 */ 1541 pmap_clear_modify(m); 1542 vm_page_undirty(m); 1543 vm_page_io_finish(m); 1544 if (vm_page_count_severe()) 1545 vm_page_try_to_cache(m); 1546 } 1547 } 1548 vm_page_unlock_queues(); 1549 1550 /* 1551 * adjust pip. NOTE: the original parent may still have its own 1552 * pip refs on the object. 1553 */ 1554 if (object != NULL) { 1555 vm_object_pip_wakeupn(object, bp->b_npages); 1556 VM_OBJECT_UNLOCK(object); 1557 } 1558 1559 /* 1560 * release the physical I/O buffer 1561 */ 1562 relpbuf( 1563 bp, 1564 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount : 1565 ((bp->b_flags & B_ASYNC) ? 1566 &nsw_wcount_async : 1567 &nsw_wcount_sync 1568 ) 1569 ) 1570 ); 1571 VM_UNLOCK_GIANT(); 1572 splx(s); 1573 } 1574 1575 /* 1576 * swap_pager_isswapped: 1577 * 1578 * Return 1 if at least one page in the given object is paged 1579 * out to the given swap device. 1580 * 1581 * This routine may not block. 1582 */ 1583 int 1584 swap_pager_isswapped(vm_object_t object, struct swdevt *sp) 1585 { 1586 daddr_t index = 0; 1587 int bcount; 1588 int i; 1589 1590 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1591 if (object->type != OBJT_SWAP) 1592 return (0); 1593 1594 mtx_lock(&swhash_mtx); 1595 for (bcount = 0; bcount < object->un_pager.swp.swp_bcount; bcount++) { 1596 struct swblock *swap; 1597 1598 if ((swap = *swp_pager_hash(object, index)) != NULL) { 1599 for (i = 0; i < SWAP_META_PAGES; ++i) { 1600 if (swp_pager_isondev(swap->swb_pages[i], sp)) { 1601 mtx_unlock(&swhash_mtx); 1602 return (1); 1603 } 1604 } 1605 } 1606 index += SWAP_META_PAGES; 1607 if (index > 0x20000000) 1608 panic("swap_pager_isswapped: failed to locate all swap meta blocks"); 1609 } 1610 mtx_unlock(&swhash_mtx); 1611 return (0); 1612 } 1613 1614 /* 1615 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in 1616 * 1617 * This routine dissociates the page at the given index within a 1618 * swap block from its backing store, paging it in if necessary. 1619 * If the page is paged in, it is placed in the inactive queue, 1620 * since it had its backing store ripped out from under it. 1621 * We also attempt to swap in all other pages in the swap block, 1622 * we only guarantee that the one at the specified index is 1623 * paged in. 1624 * 1625 * XXX - The code to page the whole block in doesn't work, so we 1626 * revert to the one-by-one behavior for now. Sigh. 1627 */ 1628 static __inline void 1629 swp_pager_force_pagein(vm_object_t object, vm_pindex_t pindex) 1630 { 1631 vm_page_t m; 1632 1633 vm_object_pip_add(object, 1); 1634 m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL|VM_ALLOC_RETRY); 1635 if (m->valid == VM_PAGE_BITS_ALL) { 1636 vm_object_pip_subtract(object, 1); 1637 vm_page_lock_queues(); 1638 vm_page_activate(m); 1639 vm_page_dirty(m); 1640 vm_page_wakeup(m); 1641 vm_page_unlock_queues(); 1642 vm_pager_page_unswapped(m); 1643 return; 1644 } 1645 1646 if (swap_pager_getpages(object, &m, 1, 0) != VM_PAGER_OK) 1647 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/ 1648 vm_object_pip_subtract(object, 1); 1649 vm_page_lock_queues(); 1650 vm_page_dirty(m); 1651 vm_page_dontneed(m); 1652 vm_page_wakeup(m); 1653 vm_page_unlock_queues(); 1654 vm_pager_page_unswapped(m); 1655 } 1656 1657 /* 1658 * swap_pager_swapoff: 1659 * 1660 * Page in all of the pages that have been paged out to the 1661 * given device. The corresponding blocks in the bitmap must be 1662 * marked as allocated and the device must be flagged SW_CLOSING. 1663 * There may be no processes swapped out to the device. 1664 * 1665 * This routine may block. 1666 */ 1667 static void 1668 swap_pager_swapoff(struct swdevt *sp) 1669 { 1670 struct swblock *swap; 1671 int i, j, retries; 1672 1673 GIANT_REQUIRED; 1674 1675 retries = 0; 1676 full_rescan: 1677 mtx_lock(&swhash_mtx); 1678 for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */ 1679 restart: 1680 for (swap = swhash[i]; swap != NULL; swap = swap->swb_hnext) { 1681 vm_object_t object = swap->swb_object; 1682 vm_pindex_t pindex = swap->swb_index; 1683 for (j = 0; j < SWAP_META_PAGES; ++j) { 1684 if (swp_pager_isondev(swap->swb_pages[j], sp)) { 1685 /* avoid deadlock */ 1686 if (!VM_OBJECT_TRYLOCK(object)) { 1687 break; 1688 } else { 1689 mtx_unlock(&swhash_mtx); 1690 swp_pager_force_pagein(object, 1691 pindex + j); 1692 VM_OBJECT_UNLOCK(object); 1693 mtx_lock(&swhash_mtx); 1694 goto restart; 1695 } 1696 } 1697 } 1698 } 1699 } 1700 mtx_unlock(&swhash_mtx); 1701 if (sp->sw_used) { 1702 int dummy; 1703 /* 1704 * Objects may be locked or paging to the device being 1705 * removed, so we will miss their pages and need to 1706 * make another pass. We have marked this device as 1707 * SW_CLOSING, so the activity should finish soon. 1708 */ 1709 retries++; 1710 if (retries > 100) { 1711 panic("swapoff: failed to locate %d swap blocks", 1712 sp->sw_used); 1713 } 1714 tsleep(&dummy, PVM, "swpoff", hz / 20); 1715 goto full_rescan; 1716 } 1717 } 1718 1719 /************************************************************************ 1720 * SWAP META DATA * 1721 ************************************************************************ 1722 * 1723 * These routines manipulate the swap metadata stored in the 1724 * OBJT_SWAP object. All swp_*() routines must be called at 1725 * splvm() because swap can be freed up by the low level vm_page 1726 * code which might be called from interrupts beyond what splbio() covers. 1727 * 1728 * Swap metadata is implemented with a global hash and not directly 1729 * linked into the object. Instead the object simply contains 1730 * appropriate tracking counters. 1731 */ 1732 1733 /* 1734 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1735 * 1736 * We first convert the object to a swap object if it is a default 1737 * object. 1738 * 1739 * The specified swapblk is added to the object's swap metadata. If 1740 * the swapblk is not valid, it is freed instead. Any previously 1741 * assigned swapblk is freed. 1742 * 1743 * This routine must be called at splvm(), except when used to convert 1744 * an OBJT_DEFAULT object into an OBJT_SWAP object. 1745 */ 1746 static void 1747 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1748 { 1749 struct swblock *swap; 1750 struct swblock **pswap; 1751 int idx; 1752 1753 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1754 /* 1755 * Convert default object to swap object if necessary 1756 */ 1757 if (object->type != OBJT_SWAP) { 1758 object->type = OBJT_SWAP; 1759 object->un_pager.swp.swp_bcount = 0; 1760 1761 if (object->handle != NULL) { 1762 mtx_lock(&sw_alloc_mtx); 1763 TAILQ_INSERT_TAIL( 1764 NOBJLIST(object->handle), 1765 object, 1766 pager_object_list 1767 ); 1768 mtx_unlock(&sw_alloc_mtx); 1769 } 1770 } 1771 1772 /* 1773 * Locate hash entry. If not found create, but if we aren't adding 1774 * anything just return. If we run out of space in the map we wait 1775 * and, since the hash table may have changed, retry. 1776 */ 1777 retry: 1778 mtx_lock(&swhash_mtx); 1779 pswap = swp_pager_hash(object, pindex); 1780 1781 if ((swap = *pswap) == NULL) { 1782 int i; 1783 1784 if (swapblk == SWAPBLK_NONE) 1785 goto done; 1786 1787 swap = *pswap = uma_zalloc(swap_zone, M_NOWAIT); 1788 if (swap == NULL) { 1789 mtx_unlock(&swhash_mtx); 1790 VM_OBJECT_UNLOCK(object); 1791 VM_WAIT; 1792 VM_OBJECT_LOCK(object); 1793 goto retry; 1794 } 1795 1796 swap->swb_hnext = NULL; 1797 swap->swb_object = object; 1798 swap->swb_index = pindex & ~(vm_pindex_t)SWAP_META_MASK; 1799 swap->swb_count = 0; 1800 1801 ++object->un_pager.swp.swp_bcount; 1802 1803 for (i = 0; i < SWAP_META_PAGES; ++i) 1804 swap->swb_pages[i] = SWAPBLK_NONE; 1805 } 1806 1807 /* 1808 * Delete prior contents of metadata 1809 */ 1810 idx = pindex & SWAP_META_MASK; 1811 1812 if (swap->swb_pages[idx] != SWAPBLK_NONE) { 1813 swp_pager_freeswapspace(swap->swb_pages[idx], 1); 1814 --swap->swb_count; 1815 } 1816 1817 /* 1818 * Enter block into metadata 1819 */ 1820 swap->swb_pages[idx] = swapblk; 1821 if (swapblk != SWAPBLK_NONE) 1822 ++swap->swb_count; 1823 done: 1824 mtx_unlock(&swhash_mtx); 1825 } 1826 1827 /* 1828 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 1829 * 1830 * The requested range of blocks is freed, with any associated swap 1831 * returned to the swap bitmap. 1832 * 1833 * This routine will free swap metadata structures as they are cleaned 1834 * out. This routine does *NOT* operate on swap metadata associated 1835 * with resident pages. 1836 * 1837 * This routine must be called at splvm() 1838 */ 1839 static void 1840 swp_pager_meta_free(vm_object_t object, vm_pindex_t index, daddr_t count) 1841 { 1842 1843 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1844 if (object->type != OBJT_SWAP) 1845 return; 1846 1847 while (count > 0) { 1848 struct swblock **pswap; 1849 struct swblock *swap; 1850 1851 mtx_lock(&swhash_mtx); 1852 pswap = swp_pager_hash(object, index); 1853 1854 if ((swap = *pswap) != NULL) { 1855 daddr_t v = swap->swb_pages[index & SWAP_META_MASK]; 1856 1857 if (v != SWAPBLK_NONE) { 1858 swp_pager_freeswapspace(v, 1); 1859 swap->swb_pages[index & SWAP_META_MASK] = 1860 SWAPBLK_NONE; 1861 if (--swap->swb_count == 0) { 1862 *pswap = swap->swb_hnext; 1863 uma_zfree(swap_zone, swap); 1864 --object->un_pager.swp.swp_bcount; 1865 } 1866 } 1867 --count; 1868 ++index; 1869 } else { 1870 int n = SWAP_META_PAGES - (index & SWAP_META_MASK); 1871 count -= n; 1872 index += n; 1873 } 1874 mtx_unlock(&swhash_mtx); 1875 } 1876 } 1877 1878 /* 1879 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 1880 * 1881 * This routine locates and destroys all swap metadata associated with 1882 * an object. 1883 * 1884 * This routine must be called at splvm() 1885 */ 1886 static void 1887 swp_pager_meta_free_all(vm_object_t object) 1888 { 1889 daddr_t index = 0; 1890 1891 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1892 if (object->type != OBJT_SWAP) 1893 return; 1894 1895 while (object->un_pager.swp.swp_bcount) { 1896 struct swblock **pswap; 1897 struct swblock *swap; 1898 1899 mtx_lock(&swhash_mtx); 1900 pswap = swp_pager_hash(object, index); 1901 if ((swap = *pswap) != NULL) { 1902 int i; 1903 1904 for (i = 0; i < SWAP_META_PAGES; ++i) { 1905 daddr_t v = swap->swb_pages[i]; 1906 if (v != SWAPBLK_NONE) { 1907 --swap->swb_count; 1908 swp_pager_freeswapspace(v, 1); 1909 } 1910 } 1911 if (swap->swb_count != 0) 1912 panic("swap_pager_meta_free_all: swb_count != 0"); 1913 *pswap = swap->swb_hnext; 1914 uma_zfree(swap_zone, swap); 1915 --object->un_pager.swp.swp_bcount; 1916 } 1917 mtx_unlock(&swhash_mtx); 1918 index += SWAP_META_PAGES; 1919 if (index > 0x20000000) 1920 panic("swp_pager_meta_free_all: failed to locate all swap meta blocks"); 1921 } 1922 } 1923 1924 /* 1925 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. 1926 * 1927 * This routine is capable of looking up, popping, or freeing 1928 * swapblk assignments in the swap meta data or in the vm_page_t. 1929 * The routine typically returns the swapblk being looked-up, or popped, 1930 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block 1931 * was invalid. This routine will automatically free any invalid 1932 * meta-data swapblks. 1933 * 1934 * It is not possible to store invalid swapblks in the swap meta data 1935 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking. 1936 * 1937 * When acting on a busy resident page and paging is in progress, we 1938 * have to wait until paging is complete but otherwise can act on the 1939 * busy page. 1940 * 1941 * This routine must be called at splvm(). 1942 * 1943 * SWM_FREE remove and free swap block from metadata 1944 * SWM_POP remove from meta data but do not free.. pop it out 1945 */ 1946 static daddr_t 1947 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags) 1948 { 1949 struct swblock **pswap; 1950 struct swblock *swap; 1951 daddr_t r1; 1952 int idx; 1953 1954 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1955 /* 1956 * The meta data only exists of the object is OBJT_SWAP 1957 * and even then might not be allocated yet. 1958 */ 1959 if (object->type != OBJT_SWAP) 1960 return (SWAPBLK_NONE); 1961 1962 r1 = SWAPBLK_NONE; 1963 mtx_lock(&swhash_mtx); 1964 pswap = swp_pager_hash(object, pindex); 1965 1966 if ((swap = *pswap) != NULL) { 1967 idx = pindex & SWAP_META_MASK; 1968 r1 = swap->swb_pages[idx]; 1969 1970 if (r1 != SWAPBLK_NONE) { 1971 if (flags & SWM_FREE) { 1972 swp_pager_freeswapspace(r1, 1); 1973 r1 = SWAPBLK_NONE; 1974 } 1975 if (flags & (SWM_FREE|SWM_POP)) { 1976 swap->swb_pages[idx] = SWAPBLK_NONE; 1977 if (--swap->swb_count == 0) { 1978 *pswap = swap->swb_hnext; 1979 uma_zfree(swap_zone, swap); 1980 --object->un_pager.swp.swp_bcount; 1981 } 1982 } 1983 } 1984 } 1985 mtx_unlock(&swhash_mtx); 1986 return (r1); 1987 } 1988 1989 /* 1990 * System call swapon(name) enables swapping on device name, 1991 * which must be in the swdevsw. Return EBUSY 1992 * if already swapping on this device. 1993 */ 1994 #ifndef _SYS_SYSPROTO_H_ 1995 struct swapon_args { 1996 char *name; 1997 }; 1998 #endif 1999 2000 /* 2001 * MPSAFE 2002 */ 2003 /* ARGSUSED */ 2004 int 2005 swapon(struct thread *td, struct swapon_args *uap) 2006 { 2007 struct vattr attr; 2008 struct vnode *vp; 2009 struct nameidata nd; 2010 int error; 2011 2012 mtx_lock(&Giant); 2013 error = suser(td); 2014 if (error) 2015 goto done2; 2016 2017 while (swdev_syscall_active) 2018 tsleep(&swdev_syscall_active, PUSER - 1, "swpon", 0); 2019 swdev_syscall_active = 1; 2020 2021 /* 2022 * Swap metadata may not fit in the KVM if we have physical 2023 * memory of >1GB. 2024 */ 2025 if (swap_zone == NULL) { 2026 error = ENOMEM; 2027 goto done; 2028 } 2029 2030 NDINIT(&nd, LOOKUP, ISOPEN | FOLLOW, UIO_USERSPACE, uap->name, td); 2031 error = namei(&nd); 2032 if (error) 2033 goto done; 2034 2035 NDFREE(&nd, NDF_ONLY_PNBUF); 2036 vp = nd.ni_vp; 2037 2038 if (vn_isdisk(vp, &error)) { 2039 error = swapongeom(td, vp); 2040 } else if (vp->v_type == VREG && 2041 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2042 (error = VOP_GETATTR(vp, &attr, td->td_ucred, td)) == 0) { 2043 /* 2044 * Allow direct swapping to NFS regular files in the same 2045 * way that nfs_mountroot() sets up diskless swapping. 2046 */ 2047 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2048 } 2049 2050 if (error) 2051 vrele(vp); 2052 done: 2053 swdev_syscall_active = 0; 2054 wakeup_one(&swdev_syscall_active); 2055 done2: 2056 mtx_unlock(&Giant); 2057 return (error); 2058 } 2059 2060 static void 2061 swaponsomething(struct vnode *vp, void *id, u_long nblks, sw_strategy_t *strategy, sw_close_t *close, dev_t dev) 2062 { 2063 struct swdevt *sp, *tsp; 2064 swblk_t dvbase; 2065 u_long mblocks; 2066 2067 /* 2068 * If we go beyond this, we get overflows in the radix 2069 * tree bitmap code. 2070 */ 2071 mblocks = 0x40000000 / BLIST_META_RADIX; 2072 if (nblks > mblocks) { 2073 printf("WARNING: reducing size to maximum of %lu blocks per swap unit\n", 2074 mblocks); 2075 nblks = mblocks; 2076 } 2077 /* 2078 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2079 * First chop nblks off to page-align it, then convert. 2080 * 2081 * sw->sw_nblks is in page-sized chunks now too. 2082 */ 2083 nblks &= ~(ctodb(1) - 1); 2084 nblks = dbtoc(nblks); 2085 2086 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2087 sp->sw_vp = vp; 2088 sp->sw_id = id; 2089 sp->sw_dev = dev; 2090 sp->sw_flags = 0; 2091 sp->sw_nblks = nblks; 2092 sp->sw_used = 0; 2093 sp->sw_strategy = strategy; 2094 sp->sw_close = close; 2095 2096 sp->sw_blist = blist_create(nblks); 2097 /* 2098 * Do not free the first two block in order to avoid overwriting 2099 * any bsd label at the front of the partition 2100 */ 2101 blist_free(sp->sw_blist, 2, nblks - 2); 2102 2103 dvbase = 0; 2104 mtx_lock(&sw_dev_mtx); 2105 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2106 if (tsp->sw_end >= dvbase) { 2107 /* 2108 * We put one uncovered page between the devices 2109 * in order to definitively prevent any cross-device 2110 * I/O requests 2111 */ 2112 dvbase = tsp->sw_end + 1; 2113 } 2114 } 2115 sp->sw_first = dvbase; 2116 sp->sw_end = dvbase + nblks; 2117 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2118 nswapdev++; 2119 swap_pager_avail += nblks; 2120 swp_sizecheck(); 2121 mtx_unlock(&sw_dev_mtx); 2122 } 2123 2124 /* 2125 * SYSCALL: swapoff(devname) 2126 * 2127 * Disable swapping on the given device. 2128 * 2129 * XXX: Badly designed system call: it should use a device index 2130 * rather than filename as specification. We keep sw_vp around 2131 * only to make this work. 2132 */ 2133 #ifndef _SYS_SYSPROTO_H_ 2134 struct swapoff_args { 2135 char *name; 2136 }; 2137 #endif 2138 2139 /* 2140 * MPSAFE 2141 */ 2142 /* ARGSUSED */ 2143 int 2144 swapoff(struct thread *td, struct swapoff_args *uap) 2145 { 2146 struct vnode *vp; 2147 struct nameidata nd; 2148 struct swdevt *sp; 2149 u_long nblks, dvbase; 2150 int error; 2151 2152 mtx_lock(&Giant); 2153 2154 error = suser(td); 2155 if (error) 2156 goto done2; 2157 2158 while (swdev_syscall_active) 2159 tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0); 2160 swdev_syscall_active = 1; 2161 2162 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, td); 2163 error = namei(&nd); 2164 if (error) 2165 goto done; 2166 NDFREE(&nd, NDF_ONLY_PNBUF); 2167 vp = nd.ni_vp; 2168 2169 mtx_lock(&sw_dev_mtx); 2170 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2171 if (sp->sw_vp == vp) 2172 goto found; 2173 } 2174 mtx_unlock(&sw_dev_mtx); 2175 error = EINVAL; 2176 goto done; 2177 found: 2178 mtx_unlock(&sw_dev_mtx); 2179 #ifdef MAC 2180 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 2181 error = mac_check_system_swapoff(td->td_ucred, vp); 2182 (void) VOP_UNLOCK(vp, 0, td); 2183 if (error != 0) 2184 goto done; 2185 #endif 2186 2187 nblks = sp->sw_nblks; 2188 2189 /* 2190 * We can turn off this swap device safely only if the 2191 * available virtual memory in the system will fit the amount 2192 * of data we will have to page back in, plus an epsilon so 2193 * the system doesn't become critically low on swap space. 2194 */ 2195 if (cnt.v_free_count + cnt.v_cache_count + swap_pager_avail < 2196 nblks + nswap_lowat) { 2197 error = ENOMEM; 2198 goto done; 2199 } 2200 2201 /* 2202 * Prevent further allocations on this device. 2203 */ 2204 mtx_lock(&sw_dev_mtx); 2205 sp->sw_flags |= SW_CLOSING; 2206 for (dvbase = 0; dvbase < sp->sw_end; dvbase += dmmax) { 2207 swap_pager_avail -= blist_fill(sp->sw_blist, 2208 dvbase, dmmax); 2209 } 2210 mtx_unlock(&sw_dev_mtx); 2211 2212 /* 2213 * Page in the contents of the device and close it. 2214 */ 2215 swap_pager_swapoff(sp); 2216 2217 sp->sw_close(td, sp); 2218 sp->sw_id = NULL; 2219 mtx_lock(&sw_dev_mtx); 2220 TAILQ_REMOVE(&swtailq, sp, sw_list); 2221 nswapdev--; 2222 if (nswapdev == 0) { 2223 swap_pager_full = 2; 2224 swap_pager_almost_full = 1; 2225 } 2226 if (swdevhd == sp) 2227 swdevhd = NULL; 2228 mtx_unlock(&sw_dev_mtx); 2229 blist_destroy(sp->sw_blist); 2230 free(sp, M_VMPGDATA); 2231 2232 done: 2233 swdev_syscall_active = 0; 2234 wakeup_one(&swdev_syscall_active); 2235 done2: 2236 mtx_unlock(&Giant); 2237 return (error); 2238 } 2239 2240 void 2241 swap_pager_status(int *total, int *used) 2242 { 2243 struct swdevt *sp; 2244 2245 *total = 0; 2246 *used = 0; 2247 mtx_lock(&sw_dev_mtx); 2248 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2249 *total += sp->sw_nblks; 2250 *used += sp->sw_used; 2251 } 2252 mtx_unlock(&sw_dev_mtx); 2253 } 2254 2255 static int 2256 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2257 { 2258 int *name = (int *)arg1; 2259 int error, n; 2260 struct xswdev xs; 2261 struct swdevt *sp; 2262 2263 if (arg2 != 1) /* name length */ 2264 return (EINVAL); 2265 2266 n = 0; 2267 mtx_lock(&sw_dev_mtx); 2268 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2269 if (n == *name) { 2270 mtx_unlock(&sw_dev_mtx); 2271 xs.xsw_version = XSWDEV_VERSION; 2272 xs.xsw_dev = sp->sw_dev; 2273 xs.xsw_flags = sp->sw_flags; 2274 xs.xsw_nblks = sp->sw_nblks; 2275 xs.xsw_used = sp->sw_used; 2276 2277 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2278 return (error); 2279 } 2280 n++; 2281 } 2282 mtx_unlock(&sw_dev_mtx); 2283 return (ENOENT); 2284 } 2285 2286 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2287 "Number of swap devices"); 2288 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD, sysctl_vm_swap_info, 2289 "Swap statistics by device"); 2290 2291 /* 2292 * vmspace_swap_count() - count the approximate swap useage in pages for a 2293 * vmspace. 2294 * 2295 * The map must be locked. 2296 * 2297 * Swap useage is determined by taking the proportional swap used by 2298 * VM objects backing the VM map. To make up for fractional losses, 2299 * if the VM object has any swap use at all the associated map entries 2300 * count for at least 1 swap page. 2301 */ 2302 int 2303 vmspace_swap_count(struct vmspace *vmspace) 2304 { 2305 vm_map_t map = &vmspace->vm_map; 2306 vm_map_entry_t cur; 2307 int count = 0; 2308 2309 for (cur = map->header.next; cur != &map->header; cur = cur->next) { 2310 vm_object_t object; 2311 2312 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 && 2313 (object = cur->object.vm_object) != NULL) { 2314 VM_OBJECT_LOCK(object); 2315 if (object->type == OBJT_SWAP && 2316 object->un_pager.swp.swp_bcount != 0) { 2317 int n = (cur->end - cur->start) / PAGE_SIZE; 2318 2319 count += object->un_pager.swp.swp_bcount * 2320 SWAP_META_PAGES * n / object->size + 1; 2321 } 2322 VM_OBJECT_UNLOCK(object); 2323 } 2324 } 2325 return (count); 2326 } 2327 2328 /* 2329 * GEOM backend 2330 * 2331 * Swapping onto disk devices. 2332 * 2333 */ 2334 2335 static g_orphan_t swapgeom_orphan; 2336 2337 static struct g_class g_swap_class = { 2338 .name = "SWAP", 2339 .version = G_VERSION, 2340 .orphan = swapgeom_orphan, 2341 }; 2342 2343 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2344 2345 2346 static void 2347 swapgeom_done(struct bio *bp2) 2348 { 2349 struct buf *bp; 2350 2351 bp = bp2->bio_caller2; 2352 bp->b_ioflags = bp2->bio_flags; 2353 if (bp2->bio_error) 2354 bp->b_ioflags |= BIO_ERROR; 2355 bp->b_resid = bp->b_bcount - bp2->bio_completed; 2356 bp->b_error = bp2->bio_error; 2357 bufdone(bp); 2358 g_destroy_bio(bp2); 2359 } 2360 2361 static void 2362 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2363 { 2364 struct bio *bio; 2365 struct g_consumer *cp; 2366 2367 cp = sp->sw_id; 2368 if (cp == NULL) { 2369 bp->b_error = ENXIO; 2370 bp->b_ioflags |= BIO_ERROR; 2371 bufdone(bp); 2372 return; 2373 } 2374 bio = g_alloc_bio(); 2375 #if 0 2376 /* 2377 * XXX: We shouldn't really sleep here when we run out of buffers 2378 * XXX: but the alternative is worse right now. 2379 */ 2380 if (bio == NULL) { 2381 bp->b_error = ENOMEM; 2382 bp->b_ioflags |= BIO_ERROR; 2383 bufdone(bp); 2384 return; 2385 } 2386 #endif 2387 bio->bio_caller2 = bp; 2388 bio->bio_cmd = bp->b_iocmd; 2389 bio->bio_data = bp->b_data; 2390 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2391 bio->bio_length = bp->b_bcount; 2392 bio->bio_done = swapgeom_done; 2393 g_io_request(bio, cp); 2394 return; 2395 } 2396 2397 static void 2398 swapgeom_orphan(struct g_consumer *cp) 2399 { 2400 struct swdevt *sp; 2401 2402 mtx_lock(&sw_dev_mtx); 2403 TAILQ_FOREACH(sp, &swtailq, sw_list) 2404 if (sp->sw_id == cp) 2405 sp->sw_id = NULL; 2406 mtx_unlock(&sw_dev_mtx); 2407 } 2408 2409 static void 2410 swapgeom_close_ev(void *arg, int flags) 2411 { 2412 struct g_consumer *cp; 2413 2414 cp = arg; 2415 g_access(cp, -1, -1, 0); 2416 g_detach(cp); 2417 g_destroy_consumer(cp); 2418 } 2419 2420 static void 2421 swapgeom_close(struct thread *td, struct swdevt *sw) 2422 { 2423 2424 /* XXX: direct call when Giant untangled */ 2425 g_waitfor_event(swapgeom_close_ev, sw->sw_id, M_WAITOK, NULL); 2426 } 2427 2428 2429 struct swh0h0 { 2430 struct cdev *dev; 2431 struct vnode *vp; 2432 int error; 2433 }; 2434 2435 static void 2436 swapongeom_ev(void *arg, int flags) 2437 { 2438 struct swh0h0 *swh; 2439 struct g_provider *pp; 2440 struct g_consumer *cp; 2441 static struct g_geom *gp; 2442 struct swdevt *sp; 2443 u_long nblks; 2444 int error; 2445 2446 swh = arg; 2447 swh->error = 0; 2448 pp = g_dev_getprovider(swh->dev); 2449 if (pp == NULL) { 2450 swh->error = ENODEV; 2451 return; 2452 } 2453 mtx_lock(&sw_dev_mtx); 2454 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2455 cp = sp->sw_id; 2456 if (cp != NULL && cp->provider == pp) { 2457 mtx_unlock(&sw_dev_mtx); 2458 swh->error = EBUSY; 2459 return; 2460 } 2461 } 2462 mtx_unlock(&sw_dev_mtx); 2463 if (gp == NULL) 2464 gp = g_new_geomf(&g_swap_class, "swap", NULL); 2465 cp = g_new_consumer(gp); 2466 g_attach(cp, pp); 2467 /* 2468 * XXX: Everytime you think you can improve the margin for 2469 * footshooting, somebody depends on the ability to do so: 2470 * savecore(8) wants to write to our swapdev so we cannot 2471 * set an exclusive count :-( 2472 */ 2473 error = g_access(cp, 1, 1, 0); 2474 if (error) { 2475 g_detach(cp); 2476 g_destroy_consumer(cp); 2477 swh->error = error; 2478 return; 2479 } 2480 nblks = pp->mediasize / DEV_BSIZE; 2481 swaponsomething(swh->vp, cp, nblks, swapgeom_strategy, 2482 swapgeom_close, dev2udev(swh->dev)); 2483 swh->error = 0; 2484 return; 2485 } 2486 2487 static int 2488 swapongeom(struct thread *td, struct vnode *vp) 2489 { 2490 int error; 2491 struct swh0h0 swh; 2492 2493 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 2494 2495 swh.dev = vp->v_rdev; 2496 swh.vp = vp; 2497 swh.error = 0; 2498 /* XXX: direct call when Giant untangled */ 2499 error = g_waitfor_event(swapongeom_ev, &swh, M_WAITOK, NULL); 2500 if (!error) 2501 error = swh.error; 2502 VOP_UNLOCK(vp, 0, td); 2503 return (error); 2504 } 2505 2506 /* 2507 * VNODE backend 2508 * 2509 * This is used mainly for network filesystem (read: probably only tested 2510 * with NFS) swapfiles. 2511 * 2512 */ 2513 2514 static void 2515 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2516 { 2517 int s; 2518 struct vnode *vp2; 2519 2520 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2521 2522 vp2 = sp->sw_id; 2523 vhold(vp2); 2524 s = splvm(); 2525 if (bp->b_iocmd == BIO_WRITE) { 2526 if (bp->b_bufobj) /* XXX: should always be true /phk */ 2527 bufobj_wdrop(bp->b_bufobj); 2528 bufobj_wref(&vp2->v_bufobj); 2529 } 2530 bp->b_vp = vp2; 2531 splx(s); 2532 bp->b_iooffset = dbtob(bp->b_blkno); 2533 bstrategy(bp); 2534 return; 2535 } 2536 2537 static void 2538 swapdev_close(struct thread *td, struct swdevt *sp) 2539 { 2540 2541 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2542 vrele(sp->sw_vp); 2543 } 2544 2545 2546 static int 2547 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2548 { 2549 struct swdevt *sp; 2550 int error; 2551 2552 if (nblks == 0) 2553 return (ENXIO); 2554 mtx_lock(&sw_dev_mtx); 2555 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2556 if (sp->sw_id == vp) { 2557 mtx_unlock(&sw_dev_mtx); 2558 return (EBUSY); 2559 } 2560 } 2561 mtx_unlock(&sw_dev_mtx); 2562 2563 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 2564 #ifdef MAC 2565 error = mac_check_system_swapon(td->td_ucred, vp); 2566 if (error == 0) 2567 #endif 2568 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, -1); 2569 (void) VOP_UNLOCK(vp, 0, td); 2570 if (error) 2571 return (error); 2572 2573 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 2574 NODEV); 2575 return (0); 2576 } 2577