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 udev_t sw_udev; 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; 222 223 /* 224 * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure 225 * calls hooked from other parts of the VM system and do not appear here. 226 * (see vm/swap_pager.h). 227 */ 228 static vm_object_t 229 swap_pager_alloc(void *handle, vm_ooffset_t size, 230 vm_prot_t prot, vm_ooffset_t offset); 231 static void swap_pager_dealloc(vm_object_t object); 232 static int swap_pager_getpages(vm_object_t, vm_page_t *, int, int); 233 static void swap_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *); 234 static boolean_t 235 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after); 236 static void swap_pager_init(void); 237 static void swap_pager_unswapped(vm_page_t); 238 static void swap_pager_swapoff(struct swdevt *sp, int *sw_used); 239 240 struct pagerops swappagerops = { 241 .pgo_init = swap_pager_init, /* early system initialization of pager */ 242 .pgo_alloc = swap_pager_alloc, /* allocate an OBJT_SWAP object */ 243 .pgo_dealloc = swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ 244 .pgo_getpages = swap_pager_getpages, /* pagein */ 245 .pgo_putpages = swap_pager_putpages, /* pageout */ 246 .pgo_haspage = swap_pager_haspage, /* get backing store status for page */ 247 .pgo_pageunswapped = swap_pager_unswapped, /* remove swap related to page */ 248 }; 249 250 /* 251 * dmmax is in page-sized chunks with the new swap system. It was 252 * dev-bsized chunks in the old. dmmax is always a power of 2. 253 * 254 * swap_*() routines are externally accessible. swp_*() routines are 255 * internal. 256 */ 257 static int dmmax; 258 static int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ 259 static int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ 260 261 SYSCTL_INT(_vm, OID_AUTO, dmmax, 262 CTLFLAG_RD, &dmmax, 0, "Maximum size of a swap block"); 263 264 static void swp_sizecheck(void); 265 static void swp_pager_async_iodone(struct buf *bp); 266 static int swapongeom(struct thread *, struct vnode *); 267 static int swaponvp(struct thread *, struct vnode *, u_long); 268 269 /* 270 * Swap bitmap functions 271 */ 272 static void swp_pager_freeswapspace(daddr_t blk, int npages); 273 static daddr_t swp_pager_getswapspace(int npages); 274 275 /* 276 * Metadata functions 277 */ 278 static struct swblock **swp_pager_hash(vm_object_t object, vm_pindex_t index); 279 static void swp_pager_meta_build(vm_object_t, vm_pindex_t, daddr_t); 280 static void swp_pager_meta_free(vm_object_t, vm_pindex_t, daddr_t); 281 static void swp_pager_meta_free_all(vm_object_t); 282 static daddr_t swp_pager_meta_ctl(vm_object_t, vm_pindex_t, int); 283 284 /* 285 * SWP_SIZECHECK() - update swap_pager_full indication 286 * 287 * update the swap_pager_almost_full indication and warn when we are 288 * about to run out of swap space, using lowat/hiwat hysteresis. 289 * 290 * Clear swap_pager_full ( task killing ) indication when lowat is met. 291 * 292 * No restrictions on call 293 * This routine may not block. 294 * This routine must be called at splvm() 295 */ 296 static void 297 swp_sizecheck(void) 298 { 299 300 if (swap_pager_avail < nswap_lowat) { 301 if (swap_pager_almost_full == 0) { 302 printf("swap_pager: out of swap space\n"); 303 swap_pager_almost_full = 1; 304 } 305 } else { 306 swap_pager_full = 0; 307 if (swap_pager_avail > nswap_hiwat) 308 swap_pager_almost_full = 0; 309 } 310 } 311 312 /* 313 * SWP_PAGER_HASH() - hash swap meta data 314 * 315 * This is an helper function which hashes the swapblk given 316 * the object and page index. It returns a pointer to a pointer 317 * to the object, or a pointer to a NULL pointer if it could not 318 * find a swapblk. 319 * 320 * This routine must be called at splvm(). 321 */ 322 static struct swblock ** 323 swp_pager_hash(vm_object_t object, vm_pindex_t index) 324 { 325 struct swblock **pswap; 326 struct swblock *swap; 327 328 index &= ~(vm_pindex_t)SWAP_META_MASK; 329 pswap = &swhash[(index ^ (int)(intptr_t)object) & swhash_mask]; 330 while ((swap = *pswap) != NULL) { 331 if (swap->swb_object == object && 332 swap->swb_index == index 333 ) { 334 break; 335 } 336 pswap = &swap->swb_hnext; 337 } 338 return (pswap); 339 } 340 341 /* 342 * SWAP_PAGER_INIT() - initialize the swap pager! 343 * 344 * Expected to be started from system init. NOTE: This code is run 345 * before much else so be careful what you depend on. Most of the VM 346 * system has yet to be initialized at this point. 347 */ 348 static void 349 swap_pager_init(void) 350 { 351 /* 352 * Initialize object lists 353 */ 354 int i; 355 356 for (i = 0; i < NOBJLISTS; ++i) 357 TAILQ_INIT(&swap_pager_object_list[i]); 358 mtx_init(&sw_alloc_mtx, "swap_pager list", NULL, MTX_DEF); 359 mtx_init(&sw_dev_mtx, "swapdev", NULL, MTX_DEF); 360 361 /* 362 * Device Stripe, in PAGE_SIZE'd blocks 363 */ 364 dmmax = SWB_NPAGES * 2; 365 } 366 367 /* 368 * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process 369 * 370 * Expected to be started from pageout process once, prior to entering 371 * its main loop. 372 */ 373 void 374 swap_pager_swap_init(void) 375 { 376 int n, n2; 377 378 /* 379 * Number of in-transit swap bp operations. Don't 380 * exhaust the pbufs completely. Make sure we 381 * initialize workable values (0 will work for hysteresis 382 * but it isn't very efficient). 383 * 384 * The nsw_cluster_max is constrained by the bp->b_pages[] 385 * array (MAXPHYS/PAGE_SIZE) and our locally defined 386 * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are 387 * constrained by the swap device interleave stripe size. 388 * 389 * Currently we hardwire nsw_wcount_async to 4. This limit is 390 * designed to prevent other I/O from having high latencies due to 391 * our pageout I/O. The value 4 works well for one or two active swap 392 * devices but is probably a little low if you have more. Even so, 393 * a higher value would probably generate only a limited improvement 394 * with three or four active swap devices since the system does not 395 * typically have to pageout at extreme bandwidths. We will want 396 * at least 2 per swap devices, and 4 is a pretty good value if you 397 * have one NFS swap device due to the command/ack latency over NFS. 398 * So it all works out pretty well. 399 */ 400 nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER); 401 402 mtx_lock(&pbuf_mtx); 403 nsw_rcount = (nswbuf + 1) / 2; 404 nsw_wcount_sync = (nswbuf + 3) / 4; 405 nsw_wcount_async = 4; 406 nsw_wcount_async_max = nsw_wcount_async; 407 mtx_unlock(&pbuf_mtx); 408 409 /* 410 * Initialize our zone. Right now I'm just guessing on the number 411 * we need based on the number of pages in the system. Each swblock 412 * can hold 16 pages, so this is probably overkill. This reservation 413 * is typically limited to around 32MB by default. 414 */ 415 n = cnt.v_page_count / 2; 416 if (maxswzone && n > maxswzone / sizeof(struct swblock)) 417 n = maxswzone / sizeof(struct swblock); 418 n2 = n; 419 swap_zone = uma_zcreate("SWAPMETA", sizeof(struct swblock), NULL, NULL, 420 NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE | UMA_ZONE_VM); 421 do { 422 if (uma_zone_set_obj(swap_zone, NULL, n)) 423 break; 424 /* 425 * if the allocation failed, try a zone two thirds the 426 * size of the previous attempt. 427 */ 428 n -= ((n + 2) / 3); 429 } while (n > 0); 430 if (swap_zone == NULL) 431 panic("failed to create swap_zone."); 432 if (n2 != n) 433 printf("Swap zone entries reduced from %d to %d.\n", n2, n); 434 n2 = n; 435 436 /* 437 * Initialize our meta-data hash table. The swapper does not need to 438 * be quite as efficient as the VM system, so we do not use an 439 * oversized hash table. 440 * 441 * n: size of hash table, must be power of 2 442 * swhash_mask: hash table index mask 443 */ 444 for (n = 1; n < n2 / 8; n *= 2) 445 ; 446 swhash = malloc(sizeof(struct swblock *) * n, M_VMPGDATA, M_WAITOK | M_ZERO); 447 swhash_mask = n - 1; 448 mtx_init(&swhash_mtx, "swap_pager swhash", NULL, MTX_DEF); 449 } 450 451 /* 452 * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate 453 * its metadata structures. 454 * 455 * This routine is called from the mmap and fork code to create a new 456 * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object 457 * and then converting it with swp_pager_meta_build(). 458 * 459 * This routine may block in vm_object_allocate() and create a named 460 * object lookup race, so we must interlock. We must also run at 461 * splvm() for the object lookup to handle races with interrupts, but 462 * we do not have to maintain splvm() in between the lookup and the 463 * add because (I believe) it is not possible to attempt to create 464 * a new swap object w/handle when a default object with that handle 465 * already exists. 466 * 467 * MPSAFE 468 */ 469 static vm_object_t 470 swap_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 471 vm_ooffset_t offset) 472 { 473 vm_object_t object; 474 vm_pindex_t pindex; 475 476 pindex = OFF_TO_IDX(offset + PAGE_MASK + size); 477 478 if (handle) { 479 mtx_lock(&Giant); 480 /* 481 * Reference existing named region or allocate new one. There 482 * should not be a race here against swp_pager_meta_build() 483 * as called from vm_page_remove() in regards to the lookup 484 * of the handle. 485 */ 486 sx_xlock(&sw_alloc_sx); 487 object = vm_pager_object_lookup(NOBJLIST(handle), handle); 488 489 if (object != NULL) { 490 vm_object_reference(object); 491 } else { 492 object = vm_object_allocate(OBJT_DEFAULT, pindex); 493 object->handle = handle; 494 495 VM_OBJECT_LOCK(object); 496 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 497 VM_OBJECT_UNLOCK(object); 498 } 499 sx_xunlock(&sw_alloc_sx); 500 mtx_unlock(&Giant); 501 } else { 502 object = vm_object_allocate(OBJT_DEFAULT, pindex); 503 504 VM_OBJECT_LOCK(object); 505 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 506 VM_OBJECT_UNLOCK(object); 507 } 508 return (object); 509 } 510 511 /* 512 * SWAP_PAGER_DEALLOC() - remove swap metadata from object 513 * 514 * The swap backing for the object is destroyed. The code is 515 * designed such that we can reinstantiate it later, but this 516 * routine is typically called only when the entire object is 517 * about to be destroyed. 518 * 519 * This routine may block, but no longer does. 520 * 521 * The object must be locked or unreferenceable. 522 */ 523 static void 524 swap_pager_dealloc(vm_object_t object) 525 { 526 int s; 527 528 /* 529 * Remove from list right away so lookups will fail if we block for 530 * pageout completion. 531 */ 532 if (object->handle != NULL) { 533 mtx_lock(&sw_alloc_mtx); 534 TAILQ_REMOVE(NOBJLIST(object->handle), object, pager_object_list); 535 mtx_unlock(&sw_alloc_mtx); 536 } 537 538 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 539 vm_object_pip_wait(object, "swpdea"); 540 541 /* 542 * Free all remaining metadata. We only bother to free it from 543 * the swap meta data. We do not attempt to free swapblk's still 544 * associated with vm_page_t's for this object. We do not care 545 * if paging is still in progress on some objects. 546 */ 547 s = splvm(); 548 swp_pager_meta_free_all(object); 549 splx(s); 550 } 551 552 /************************************************************************ 553 * SWAP PAGER BITMAP ROUTINES * 554 ************************************************************************/ 555 556 /* 557 * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space 558 * 559 * Allocate swap for the requested number of pages. The starting 560 * swap block number (a page index) is returned or SWAPBLK_NONE 561 * if the allocation failed. 562 * 563 * Also has the side effect of advising that somebody made a mistake 564 * when they configured swap and didn't configure enough. 565 * 566 * Must be called at splvm() to avoid races with bitmap frees from 567 * vm_page_remove() aka swap_pager_page_removed(). 568 * 569 * This routine may not block 570 * This routine must be called at splvm(). 571 * 572 * We allocate in round-robin fashion from the configured devices. 573 */ 574 static daddr_t 575 swp_pager_getswapspace(int npages) 576 { 577 daddr_t blk; 578 struct swdevt *sp; 579 int i; 580 581 blk = SWAPBLK_NONE; 582 mtx_lock(&sw_dev_mtx); 583 sp = swdevhd; 584 for (i = 0; i < nswapdev; i++) { 585 if (sp == NULL) 586 sp = TAILQ_FIRST(&swtailq); 587 if (!(sp->sw_flags & SW_CLOSING)) { 588 blk = blist_alloc(sp->sw_blist, npages); 589 if (blk != SWAPBLK_NONE) { 590 blk += sp->sw_first; 591 sp->sw_used += npages; 592 swap_pager_avail -= npages; 593 swp_sizecheck(); 594 swdevhd = TAILQ_NEXT(sp, sw_list); 595 goto done; 596 } 597 } 598 sp = TAILQ_NEXT(sp, sw_list); 599 } 600 if (swap_pager_full != 2) { 601 printf("swap_pager_getswapspace(%d): failed\n", npages); 602 swap_pager_full = 2; 603 swap_pager_almost_full = 1; 604 } 605 swdevhd = NULL; 606 done: 607 mtx_unlock(&sw_dev_mtx); 608 return (blk); 609 } 610 611 static struct swdevt * 612 swp_pager_find_dev(daddr_t blk) 613 { 614 struct swdevt *sp; 615 616 mtx_lock(&sw_dev_mtx); 617 TAILQ_FOREACH(sp, &swtailq, sw_list) { 618 if (blk >= sp->sw_first && blk < sp->sw_end) { 619 mtx_unlock(&sw_dev_mtx); 620 return (sp); 621 } 622 } 623 panic("Swapdev not found"); 624 } 625 626 static void 627 swp_pager_strategy(struct buf *bp) 628 { 629 struct swdevt *sp; 630 631 mtx_lock(&sw_dev_mtx); 632 TAILQ_FOREACH(sp, &swtailq, sw_list) { 633 if (bp->b_blkno >= sp->sw_first && bp->b_blkno < sp->sw_end) { 634 mtx_unlock(&sw_dev_mtx); 635 sp->sw_strategy(bp, sp); 636 return; 637 } 638 } 639 panic("Swapdev not found"); 640 } 641 642 643 /* 644 * SWP_PAGER_FREESWAPSPACE() - free raw swap space 645 * 646 * This routine returns the specified swap blocks back to the bitmap. 647 * 648 * Note: This routine may not block (it could in the old swap code), 649 * and through the use of the new blist routines it does not block. 650 * 651 * We must be called at splvm() to avoid races with bitmap frees from 652 * vm_page_remove() aka swap_pager_page_removed(). 653 * 654 * This routine may not block 655 * This routine must be called at splvm(). 656 */ 657 static void 658 swp_pager_freeswapspace(daddr_t blk, int npages) 659 { 660 struct swdevt *sp; 661 662 mtx_lock(&sw_dev_mtx); 663 TAILQ_FOREACH(sp, &swtailq, sw_list) { 664 if (blk >= sp->sw_first && blk < sp->sw_end) { 665 sp->sw_used -= npages; 666 /* 667 * If we are attempting to stop swapping on 668 * this device, we don't want to mark any 669 * blocks free lest they be reused. 670 */ 671 if ((sp->sw_flags & SW_CLOSING) == 0) { 672 blist_free(sp->sw_blist, blk - sp->sw_first, 673 npages); 674 swap_pager_avail += npages; 675 swp_sizecheck(); 676 } 677 mtx_unlock(&sw_dev_mtx); 678 return; 679 } 680 } 681 panic("Swapdev not found"); 682 } 683 684 /* 685 * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page 686 * range within an object. 687 * 688 * This is a globally accessible routine. 689 * 690 * This routine removes swapblk assignments from swap metadata. 691 * 692 * The external callers of this routine typically have already destroyed 693 * or renamed vm_page_t's associated with this range in the object so 694 * we should be ok. 695 * 696 * This routine may be called at any spl. We up our spl to splvm temporarily 697 * in order to perform the metadata removal. 698 */ 699 void 700 swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_size_t size) 701 { 702 int s = splvm(); 703 704 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 705 swp_pager_meta_free(object, start, size); 706 splx(s); 707 } 708 709 /* 710 * SWAP_PAGER_RESERVE() - reserve swap blocks in object 711 * 712 * Assigns swap blocks to the specified range within the object. The 713 * swap blocks are not zerod. Any previous swap assignment is destroyed. 714 * 715 * Returns 0 on success, -1 on failure. 716 */ 717 int 718 swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) 719 { 720 int s; 721 int n = 0; 722 daddr_t blk = SWAPBLK_NONE; 723 vm_pindex_t beg = start; /* save start index */ 724 725 s = splvm(); 726 VM_OBJECT_LOCK(object); 727 while (size) { 728 if (n == 0) { 729 n = BLIST_MAX_ALLOC; 730 while ((blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE) { 731 n >>= 1; 732 if (n == 0) { 733 swp_pager_meta_free(object, beg, start - beg); 734 VM_OBJECT_UNLOCK(object); 735 splx(s); 736 return (-1); 737 } 738 } 739 } 740 swp_pager_meta_build(object, start, blk); 741 --size; 742 ++start; 743 ++blk; 744 --n; 745 } 746 swp_pager_meta_free(object, start, n); 747 VM_OBJECT_UNLOCK(object); 748 splx(s); 749 return (0); 750 } 751 752 /* 753 * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager 754 * and destroy the source. 755 * 756 * Copy any valid swapblks from the source to the destination. In 757 * cases where both the source and destination have a valid swapblk, 758 * we keep the destination's. 759 * 760 * This routine is allowed to block. It may block allocating metadata 761 * indirectly through swp_pager_meta_build() or if paging is still in 762 * progress on the source. 763 * 764 * This routine can be called at any spl 765 * 766 * XXX vm_page_collapse() kinda expects us not to block because we 767 * supposedly do not need to allocate memory, but for the moment we 768 * *may* have to get a little memory from the zone allocator, but 769 * it is taken from the interrupt memory. We should be ok. 770 * 771 * The source object contains no vm_page_t's (which is just as well) 772 * 773 * The source object is of type OBJT_SWAP. 774 * 775 * The source and destination objects must be locked or 776 * inaccessible (XXX are they ?) 777 */ 778 void 779 swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, 780 vm_pindex_t offset, int destroysource) 781 { 782 vm_pindex_t i; 783 int s; 784 785 VM_OBJECT_LOCK_ASSERT(srcobject, MA_OWNED); 786 VM_OBJECT_LOCK_ASSERT(dstobject, MA_OWNED); 787 788 s = splvm(); 789 /* 790 * If destroysource is set, we remove the source object from the 791 * swap_pager internal queue now. 792 */ 793 if (destroysource) { 794 if (srcobject->handle != NULL) { 795 mtx_lock(&sw_alloc_mtx); 796 TAILQ_REMOVE( 797 NOBJLIST(srcobject->handle), 798 srcobject, 799 pager_object_list 800 ); 801 mtx_unlock(&sw_alloc_mtx); 802 } 803 } 804 805 /* 806 * transfer source to destination. 807 */ 808 for (i = 0; i < dstobject->size; ++i) { 809 daddr_t dstaddr; 810 811 /* 812 * Locate (without changing) the swapblk on the destination, 813 * unless it is invalid in which case free it silently, or 814 * if the destination is a resident page, in which case the 815 * source is thrown away. 816 */ 817 dstaddr = swp_pager_meta_ctl(dstobject, i, 0); 818 819 if (dstaddr == SWAPBLK_NONE) { 820 /* 821 * Destination has no swapblk and is not resident, 822 * copy source. 823 */ 824 daddr_t srcaddr; 825 826 srcaddr = swp_pager_meta_ctl( 827 srcobject, 828 i + offset, 829 SWM_POP 830 ); 831 832 if (srcaddr != SWAPBLK_NONE) { 833 /* 834 * swp_pager_meta_build() can sleep. 835 */ 836 vm_object_pip_add(srcobject, 1); 837 VM_OBJECT_UNLOCK(srcobject); 838 vm_object_pip_add(dstobject, 1); 839 swp_pager_meta_build(dstobject, i, srcaddr); 840 vm_object_pip_wakeup(dstobject); 841 VM_OBJECT_LOCK(srcobject); 842 vm_object_pip_wakeup(srcobject); 843 } 844 } else { 845 /* 846 * Destination has valid swapblk or it is represented 847 * by a resident page. We destroy the sourceblock. 848 */ 849 850 swp_pager_meta_ctl(srcobject, i + offset, SWM_FREE); 851 } 852 } 853 854 /* 855 * Free left over swap blocks in source. 856 * 857 * We have to revert the type to OBJT_DEFAULT so we do not accidently 858 * double-remove the object from the swap queues. 859 */ 860 if (destroysource) { 861 swp_pager_meta_free_all(srcobject); 862 /* 863 * Reverting the type is not necessary, the caller is going 864 * to destroy srcobject directly, but I'm doing it here 865 * for consistency since we've removed the object from its 866 * queues. 867 */ 868 srcobject->type = OBJT_DEFAULT; 869 } 870 splx(s); 871 } 872 873 /* 874 * SWAP_PAGER_HASPAGE() - determine if we have good backing store for 875 * the requested page. 876 * 877 * We determine whether good backing store exists for the requested 878 * page and return TRUE if it does, FALSE if it doesn't. 879 * 880 * If TRUE, we also try to determine how much valid, contiguous backing 881 * store exists before and after the requested page within a reasonable 882 * distance. We do not try to restrict it to the swap device stripe 883 * (that is handled in getpages/putpages). It probably isn't worth 884 * doing here. 885 */ 886 static boolean_t 887 swap_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, int *after) 888 { 889 daddr_t blk0; 890 int s; 891 892 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 893 /* 894 * do we have good backing store at the requested index ? 895 */ 896 s = splvm(); 897 blk0 = swp_pager_meta_ctl(object, pindex, 0); 898 899 if (blk0 == SWAPBLK_NONE) { 900 splx(s); 901 if (before) 902 *before = 0; 903 if (after) 904 *after = 0; 905 return (FALSE); 906 } 907 908 /* 909 * find backwards-looking contiguous good backing store 910 */ 911 if (before != NULL) { 912 int i; 913 914 for (i = 1; i < (SWB_NPAGES/2); ++i) { 915 daddr_t blk; 916 917 if (i > pindex) 918 break; 919 blk = swp_pager_meta_ctl(object, pindex - i, 0); 920 if (blk != blk0 - i) 921 break; 922 } 923 *before = (i - 1); 924 } 925 926 /* 927 * find forward-looking contiguous good backing store 928 */ 929 if (after != NULL) { 930 int i; 931 932 for (i = 1; i < (SWB_NPAGES/2); ++i) { 933 daddr_t blk; 934 935 blk = swp_pager_meta_ctl(object, pindex + i, 0); 936 if (blk != blk0 + i) 937 break; 938 } 939 *after = (i - 1); 940 } 941 splx(s); 942 return (TRUE); 943 } 944 945 /* 946 * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page 947 * 948 * This removes any associated swap backing store, whether valid or 949 * not, from the page. 950 * 951 * This routine is typically called when a page is made dirty, at 952 * which point any associated swap can be freed. MADV_FREE also 953 * calls us in a special-case situation 954 * 955 * NOTE!!! If the page is clean and the swap was valid, the caller 956 * should make the page dirty before calling this routine. This routine 957 * does NOT change the m->dirty status of the page. Also: MADV_FREE 958 * depends on it. 959 * 960 * This routine may not block 961 * This routine must be called at splvm() 962 */ 963 static void 964 swap_pager_unswapped(vm_page_t m) 965 { 966 967 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 968 swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); 969 } 970 971 /* 972 * SWAP_PAGER_GETPAGES() - bring pages in from swap 973 * 974 * Attempt to retrieve (m, count) pages from backing store, but make 975 * sure we retrieve at least m[reqpage]. We try to load in as large 976 * a chunk surrounding m[reqpage] as is contiguous in swap and which 977 * belongs to the same object. 978 * 979 * The code is designed for asynchronous operation and 980 * immediate-notification of 'reqpage' but tends not to be 981 * used that way. Please do not optimize-out this algorithmic 982 * feature, I intend to improve on it in the future. 983 * 984 * The parent has a single vm_object_pip_add() reference prior to 985 * calling us and we should return with the same. 986 * 987 * The parent has BUSY'd the pages. We should return with 'm' 988 * left busy, but the others adjusted. 989 */ 990 static int 991 swap_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage) 992 { 993 struct buf *bp; 994 vm_page_t mreq; 995 int s; 996 int i; 997 int j; 998 daddr_t blk; 999 1000 mreq = m[reqpage]; 1001 1002 KASSERT(mreq->object == object, 1003 ("swap_pager_getpages: object mismatch %p/%p", 1004 object, mreq->object)); 1005 1006 /* 1007 * Calculate range to retrieve. The pages have already been assigned 1008 * their swapblks. We require a *contiguous* range but we know it to 1009 * not span devices. If we do not supply it, bad things 1010 * happen. Note that blk, iblk & jblk can be SWAPBLK_NONE, but the 1011 * loops are set up such that the case(s) are handled implicitly. 1012 * 1013 * The swp_*() calls must be made at splvm(). vm_page_free() does 1014 * not need to be, but it will go a little faster if it is. 1015 */ 1016 s = splvm(); 1017 blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0); 1018 1019 for (i = reqpage - 1; i >= 0; --i) { 1020 daddr_t iblk; 1021 1022 iblk = swp_pager_meta_ctl(m[i]->object, m[i]->pindex, 0); 1023 if (blk != iblk + (reqpage - i)) 1024 break; 1025 } 1026 ++i; 1027 1028 for (j = reqpage + 1; j < count; ++j) { 1029 daddr_t jblk; 1030 1031 jblk = swp_pager_meta_ctl(m[j]->object, m[j]->pindex, 0); 1032 if (blk != jblk - (j - reqpage)) 1033 break; 1034 } 1035 1036 /* 1037 * free pages outside our collection range. Note: we never free 1038 * mreq, it must remain busy throughout. 1039 */ 1040 vm_page_lock_queues(); 1041 { 1042 int k; 1043 1044 for (k = 0; k < i; ++k) 1045 vm_page_free(m[k]); 1046 for (k = j; k < count; ++k) 1047 vm_page_free(m[k]); 1048 } 1049 vm_page_unlock_queues(); 1050 splx(s); 1051 1052 1053 /* 1054 * Return VM_PAGER_FAIL if we have nothing to do. Return mreq 1055 * still busy, but the others unbusied. 1056 */ 1057 if (blk == SWAPBLK_NONE) 1058 return (VM_PAGER_FAIL); 1059 1060 /* 1061 * Getpbuf() can sleep. 1062 */ 1063 VM_OBJECT_UNLOCK(object); 1064 /* 1065 * Get a swap buffer header to perform the IO 1066 */ 1067 bp = getpbuf(&nsw_rcount); 1068 bp->b_flags |= B_PAGING; 1069 1070 /* 1071 * map our page(s) into kva for input 1072 */ 1073 pmap_qenter((vm_offset_t)bp->b_data, m + i, j - i); 1074 1075 bp->b_iocmd = BIO_READ; 1076 bp->b_iodone = swp_pager_async_iodone; 1077 bp->b_rcred = crhold(thread0.td_ucred); 1078 bp->b_wcred = crhold(thread0.td_ucred); 1079 bp->b_blkno = blk - (reqpage - i); 1080 bp->b_bcount = PAGE_SIZE * (j - i); 1081 bp->b_bufsize = PAGE_SIZE * (j - i); 1082 bp->b_pager.pg_reqpage = reqpage - i; 1083 1084 VM_OBJECT_LOCK(object); 1085 vm_page_lock_queues(); 1086 { 1087 int k; 1088 1089 for (k = i; k < j; ++k) { 1090 bp->b_pages[k - i] = m[k]; 1091 vm_page_flag_set(m[k], PG_SWAPINPROG); 1092 } 1093 } 1094 vm_page_unlock_queues(); 1095 VM_OBJECT_UNLOCK(object); 1096 bp->b_npages = j - i; 1097 1098 cnt.v_swapin++; 1099 cnt.v_swappgsin += bp->b_npages; 1100 1101 /* 1102 * We still hold the lock on mreq, and our automatic completion routine 1103 * does not remove it. 1104 */ 1105 VM_OBJECT_LOCK(mreq->object); 1106 vm_object_pip_add(mreq->object, bp->b_npages); 1107 VM_OBJECT_UNLOCK(mreq->object); 1108 1109 /* 1110 * perform the I/O. NOTE!!! bp cannot be considered valid after 1111 * this point because we automatically release it on completion. 1112 * Instead, we look at the one page we are interested in which we 1113 * still hold a lock on even through the I/O completion. 1114 * 1115 * The other pages in our m[] array are also released on completion, 1116 * so we cannot assume they are valid anymore either. 1117 * 1118 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1119 */ 1120 BUF_KERNPROC(bp); 1121 swp_pager_strategy(bp); 1122 1123 /* 1124 * wait for the page we want to complete. PG_SWAPINPROG is always 1125 * cleared on completion. If an I/O error occurs, SWAPBLK_NONE 1126 * is set in the meta-data. 1127 */ 1128 s = splvm(); 1129 vm_page_lock_queues(); 1130 while ((mreq->flags & PG_SWAPINPROG) != 0) { 1131 vm_page_flag_set(mreq, PG_WANTED | PG_REFERENCED); 1132 cnt.v_intrans++; 1133 if (msleep(mreq, &vm_page_queue_mtx, PSWP, "swread", hz*20)) { 1134 printf( 1135 "swap_pager: indefinite wait buffer: device:" 1136 " %s, blkno: %ld, size: %ld\n", 1137 devtoname(bp->b_dev), (long)bp->b_blkno, 1138 bp->b_bcount 1139 ); 1140 } 1141 } 1142 vm_page_unlock_queues(); 1143 splx(s); 1144 1145 VM_OBJECT_LOCK(mreq->object); 1146 /* 1147 * mreq is left busied after completion, but all the other pages 1148 * are freed. If we had an unrecoverable read error the page will 1149 * not be valid. 1150 */ 1151 if (mreq->valid != VM_PAGE_BITS_ALL) { 1152 return (VM_PAGER_ERROR); 1153 } else { 1154 return (VM_PAGER_OK); 1155 } 1156 1157 /* 1158 * A final note: in a low swap situation, we cannot deallocate swap 1159 * and mark a page dirty here because the caller is likely to mark 1160 * the page clean when we return, causing the page to possibly revert 1161 * to all-zero's later. 1162 */ 1163 } 1164 1165 /* 1166 * swap_pager_putpages: 1167 * 1168 * Assign swap (if necessary) and initiate I/O on the specified pages. 1169 * 1170 * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects 1171 * are automatically converted to SWAP objects. 1172 * 1173 * In a low memory situation we may block in VOP_STRATEGY(), but the new 1174 * vm_page reservation system coupled with properly written VFS devices 1175 * should ensure that no low-memory deadlock occurs. This is an area 1176 * which needs work. 1177 * 1178 * The parent has N vm_object_pip_add() references prior to 1179 * calling us and will remove references for rtvals[] that are 1180 * not set to VM_PAGER_PEND. We need to remove the rest on I/O 1181 * completion. 1182 * 1183 * The parent has soft-busy'd the pages it passes us and will unbusy 1184 * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. 1185 * We need to unbusy the rest on I/O completion. 1186 */ 1187 void 1188 swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1189 boolean_t sync, int *rtvals) 1190 { 1191 int i; 1192 int n = 0; 1193 1194 GIANT_REQUIRED; 1195 if (count && m[0]->object != object) { 1196 panic("swap_pager_getpages: object mismatch %p/%p", 1197 object, 1198 m[0]->object 1199 ); 1200 } 1201 1202 /* 1203 * Step 1 1204 * 1205 * Turn object into OBJT_SWAP 1206 * check for bogus sysops 1207 * force sync if not pageout process 1208 */ 1209 if (object->type != OBJT_SWAP) 1210 swp_pager_meta_build(object, 0, SWAPBLK_NONE); 1211 VM_OBJECT_UNLOCK(object); 1212 1213 if (curproc != pageproc) 1214 sync = TRUE; 1215 1216 /* 1217 * Step 2 1218 * 1219 * Update nsw parameters from swap_async_max sysctl values. 1220 * Do not let the sysop crash the machine with bogus numbers. 1221 */ 1222 mtx_lock(&pbuf_mtx); 1223 if (swap_async_max != nsw_wcount_async_max) { 1224 int n; 1225 int s; 1226 1227 /* 1228 * limit range 1229 */ 1230 if ((n = swap_async_max) > nswbuf / 2) 1231 n = nswbuf / 2; 1232 if (n < 1) 1233 n = 1; 1234 swap_async_max = n; 1235 1236 /* 1237 * Adjust difference ( if possible ). If the current async 1238 * count is too low, we may not be able to make the adjustment 1239 * at this time. 1240 */ 1241 s = splvm(); 1242 n -= nsw_wcount_async_max; 1243 if (nsw_wcount_async + n >= 0) { 1244 nsw_wcount_async += n; 1245 nsw_wcount_async_max += n; 1246 wakeup(&nsw_wcount_async); 1247 } 1248 splx(s); 1249 } 1250 mtx_unlock(&pbuf_mtx); 1251 1252 /* 1253 * Step 3 1254 * 1255 * Assign swap blocks and issue I/O. We reallocate swap on the fly. 1256 * The page is left dirty until the pageout operation completes 1257 * successfully. 1258 */ 1259 for (i = 0; i < count; i += n) { 1260 int s; 1261 int j; 1262 struct buf *bp; 1263 daddr_t blk; 1264 1265 /* 1266 * Maximum I/O size is limited by a number of factors. 1267 */ 1268 n = min(BLIST_MAX_ALLOC, count - i); 1269 n = min(n, nsw_cluster_max); 1270 1271 s = splvm(); 1272 1273 /* 1274 * Get biggest block of swap we can. If we fail, fall 1275 * back and try to allocate a smaller block. Don't go 1276 * overboard trying to allocate space if it would overly 1277 * fragment swap. 1278 */ 1279 while ( 1280 (blk = swp_pager_getswapspace(n)) == SWAPBLK_NONE && 1281 n > 4 1282 ) { 1283 n >>= 1; 1284 } 1285 if (blk == SWAPBLK_NONE) { 1286 for (j = 0; j < n; ++j) 1287 rtvals[i+j] = VM_PAGER_FAIL; 1288 splx(s); 1289 continue; 1290 } 1291 1292 /* 1293 * All I/O parameters have been satisfied, build the I/O 1294 * request and assign the swap space. 1295 */ 1296 if (sync == TRUE) { 1297 bp = getpbuf(&nsw_wcount_sync); 1298 } else { 1299 bp = getpbuf(&nsw_wcount_async); 1300 bp->b_flags = B_ASYNC; 1301 } 1302 bp->b_flags |= B_PAGING; 1303 bp->b_iocmd = BIO_WRITE; 1304 1305 pmap_qenter((vm_offset_t)bp->b_data, &m[i], n); 1306 1307 bp->b_rcred = crhold(thread0.td_ucred); 1308 bp->b_wcred = crhold(thread0.td_ucred); 1309 bp->b_bcount = PAGE_SIZE * n; 1310 bp->b_bufsize = PAGE_SIZE * n; 1311 bp->b_blkno = blk; 1312 1313 VM_OBJECT_LOCK(object); 1314 for (j = 0; j < n; ++j) { 1315 vm_page_t mreq = m[i+j]; 1316 1317 swp_pager_meta_build( 1318 mreq->object, 1319 mreq->pindex, 1320 blk + j 1321 ); 1322 vm_page_dirty(mreq); 1323 rtvals[i+j] = VM_PAGER_OK; 1324 1325 vm_page_lock_queues(); 1326 vm_page_flag_set(mreq, PG_SWAPINPROG); 1327 vm_page_unlock_queues(); 1328 bp->b_pages[j] = mreq; 1329 } 1330 VM_OBJECT_UNLOCK(object); 1331 bp->b_npages = n; 1332 /* 1333 * Must set dirty range for NFS to work. 1334 */ 1335 bp->b_dirtyoff = 0; 1336 bp->b_dirtyend = bp->b_bcount; 1337 1338 cnt.v_swapout++; 1339 cnt.v_swappgsout += bp->b_npages; 1340 1341 splx(s); 1342 1343 /* 1344 * asynchronous 1345 * 1346 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1347 */ 1348 if (sync == FALSE) { 1349 bp->b_iodone = swp_pager_async_iodone; 1350 BUF_KERNPROC(bp); 1351 swp_pager_strategy(bp); 1352 1353 for (j = 0; j < n; ++j) 1354 rtvals[i+j] = VM_PAGER_PEND; 1355 /* restart outter loop */ 1356 continue; 1357 } 1358 1359 /* 1360 * synchronous 1361 * 1362 * NOTE: b_blkno is destroyed by the call to swapdev_strategy 1363 */ 1364 bp->b_iodone = bdone; 1365 swp_pager_strategy(bp); 1366 1367 /* 1368 * Wait for the sync I/O to complete, then update rtvals. 1369 * We just set the rtvals[] to VM_PAGER_PEND so we can call 1370 * our async completion routine at the end, thus avoiding a 1371 * double-free. 1372 */ 1373 s = splbio(); 1374 bwait(bp, PVM, "swwrt"); 1375 for (j = 0; j < n; ++j) 1376 rtvals[i+j] = VM_PAGER_PEND; 1377 /* 1378 * Now that we are through with the bp, we can call the 1379 * normal async completion, which frees everything up. 1380 */ 1381 swp_pager_async_iodone(bp); 1382 splx(s); 1383 } 1384 VM_OBJECT_LOCK(object); 1385 } 1386 1387 /* 1388 * swp_pager_async_iodone: 1389 * 1390 * Completion routine for asynchronous reads and writes from/to swap. 1391 * Also called manually by synchronous code to finish up a bp. 1392 * 1393 * For READ operations, the pages are PG_BUSY'd. For WRITE operations, 1394 * the pages are vm_page_t->busy'd. For READ operations, we PG_BUSY 1395 * unbusy all pages except the 'main' request page. For WRITE 1396 * operations, we vm_page_t->busy'd unbusy all pages ( we can do this 1397 * because we marked them all VM_PAGER_PEND on return from putpages ). 1398 * 1399 * This routine may not block. 1400 * This routine is called at splbio() or better 1401 * 1402 * We up ourselves to splvm() as required for various vm_page related 1403 * calls. 1404 */ 1405 static void 1406 swp_pager_async_iodone(struct buf *bp) 1407 { 1408 int s; 1409 int i; 1410 vm_object_t object = NULL; 1411 1412 bp->b_flags |= B_DONE; 1413 1414 /* 1415 * report error 1416 */ 1417 if (bp->b_ioflags & BIO_ERROR) { 1418 printf( 1419 "swap_pager: I/O error - %s failed; blkno %ld," 1420 "size %ld, error %d\n", 1421 ((bp->b_iocmd == BIO_READ) ? "pagein" : "pageout"), 1422 (long)bp->b_blkno, 1423 (long)bp->b_bcount, 1424 bp->b_error 1425 ); 1426 } 1427 1428 /* 1429 * set object, raise to splvm(). 1430 */ 1431 s = splvm(); 1432 1433 /* 1434 * remove the mapping for kernel virtual 1435 */ 1436 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1437 1438 if (bp->b_npages) { 1439 object = bp->b_pages[0]->object; 1440 VM_OBJECT_LOCK(object); 1441 } 1442 vm_page_lock_queues(); 1443 /* 1444 * cleanup pages. If an error occurs writing to swap, we are in 1445 * very serious trouble. If it happens to be a disk error, though, 1446 * we may be able to recover by reassigning the swap later on. So 1447 * in this case we remove the m->swapblk assignment for the page 1448 * but do not free it in the rlist. The errornous block(s) are thus 1449 * never reallocated as swap. Redirty the page and continue. 1450 */ 1451 for (i = 0; i < bp->b_npages; ++i) { 1452 vm_page_t m = bp->b_pages[i]; 1453 1454 vm_page_flag_clear(m, PG_SWAPINPROG); 1455 1456 if (bp->b_ioflags & BIO_ERROR) { 1457 /* 1458 * If an error occurs I'd love to throw the swapblk 1459 * away without freeing it back to swapspace, so it 1460 * can never be used again. But I can't from an 1461 * interrupt. 1462 */ 1463 if (bp->b_iocmd == BIO_READ) { 1464 /* 1465 * When reading, reqpage needs to stay 1466 * locked for the parent, but all other 1467 * pages can be freed. We still want to 1468 * wakeup the parent waiting on the page, 1469 * though. ( also: pg_reqpage can be -1 and 1470 * not match anything ). 1471 * 1472 * We have to wake specifically requested pages 1473 * up too because we cleared PG_SWAPINPROG and 1474 * someone may be waiting for that. 1475 * 1476 * NOTE: for reads, m->dirty will probably 1477 * be overridden by the original caller of 1478 * getpages so don't play cute tricks here. 1479 * 1480 * XXX IT IS NOT LEGAL TO FREE THE PAGE HERE 1481 * AS THIS MESSES WITH object->memq, and it is 1482 * not legal to mess with object->memq from an 1483 * interrupt. 1484 */ 1485 m->valid = 0; 1486 if (i != bp->b_pager.pg_reqpage) 1487 vm_page_free(m); 1488 else 1489 vm_page_flash(m); 1490 /* 1491 * If i == bp->b_pager.pg_reqpage, do not wake 1492 * the page up. The caller needs to. 1493 */ 1494 } else { 1495 /* 1496 * If a write error occurs, reactivate page 1497 * so it doesn't clog the inactive list, 1498 * then finish the I/O. 1499 */ 1500 vm_page_dirty(m); 1501 vm_page_activate(m); 1502 vm_page_io_finish(m); 1503 } 1504 } else if (bp->b_iocmd == BIO_READ) { 1505 /* 1506 * For read success, clear dirty bits. Nobody should 1507 * have this page mapped but don't take any chances, 1508 * make sure the pmap modify bits are also cleared. 1509 * 1510 * NOTE: for reads, m->dirty will probably be 1511 * overridden by the original caller of getpages so 1512 * we cannot set them in order to free the underlying 1513 * swap in a low-swap situation. I don't think we'd 1514 * want to do that anyway, but it was an optimization 1515 * that existed in the old swapper for a time before 1516 * it got ripped out due to precisely this problem. 1517 * 1518 * If not the requested page then deactivate it. 1519 * 1520 * Note that the requested page, reqpage, is left 1521 * busied, but we still have to wake it up. The 1522 * other pages are released (unbusied) by 1523 * vm_page_wakeup(). We do not set reqpage's 1524 * valid bits here, it is up to the caller. 1525 */ 1526 pmap_clear_modify(m); 1527 m->valid = VM_PAGE_BITS_ALL; 1528 vm_page_undirty(m); 1529 1530 /* 1531 * We have to wake specifically requested pages 1532 * up too because we cleared PG_SWAPINPROG and 1533 * could be waiting for it in getpages. However, 1534 * be sure to not unbusy getpages specifically 1535 * requested page - getpages expects it to be 1536 * left busy. 1537 */ 1538 if (i != bp->b_pager.pg_reqpage) { 1539 vm_page_deactivate(m); 1540 vm_page_wakeup(m); 1541 } else { 1542 vm_page_flash(m); 1543 } 1544 } else { 1545 /* 1546 * For write success, clear the modify and dirty 1547 * status, then finish the I/O ( which decrements the 1548 * busy count and possibly wakes waiter's up ). 1549 */ 1550 pmap_clear_modify(m); 1551 vm_page_undirty(m); 1552 vm_page_io_finish(m); 1553 if (vm_page_count_severe()) 1554 vm_page_try_to_cache(m); 1555 } 1556 } 1557 vm_page_unlock_queues(); 1558 1559 /* 1560 * adjust pip. NOTE: the original parent may still have its own 1561 * pip refs on the object. 1562 */ 1563 if (object != NULL) { 1564 vm_object_pip_wakeupn(object, bp->b_npages); 1565 VM_OBJECT_UNLOCK(object); 1566 } 1567 1568 /* 1569 * release the physical I/O buffer 1570 */ 1571 relpbuf( 1572 bp, 1573 ((bp->b_iocmd == BIO_READ) ? &nsw_rcount : 1574 ((bp->b_flags & B_ASYNC) ? 1575 &nsw_wcount_async : 1576 &nsw_wcount_sync 1577 ) 1578 ) 1579 ); 1580 splx(s); 1581 } 1582 1583 /* 1584 * swap_pager_isswapped: 1585 * 1586 * Return 1 if at least one page in the given object is paged 1587 * out to the given swap device. 1588 * 1589 * This routine may not block. 1590 */ 1591 int 1592 swap_pager_isswapped(vm_object_t object, struct swdevt *sp) 1593 { 1594 daddr_t index = 0; 1595 int bcount; 1596 int i; 1597 1598 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1599 for (bcount = 0; bcount < object->un_pager.swp.swp_bcount; bcount++) { 1600 struct swblock *swap; 1601 1602 mtx_lock(&swhash_mtx); 1603 if ((swap = *swp_pager_hash(object, index)) != NULL) { 1604 for (i = 0; i < SWAP_META_PAGES; ++i) { 1605 daddr_t v = swap->swb_pages[i]; 1606 if (v == SWAPBLK_NONE) 1607 continue; 1608 if (swp_pager_find_dev(v) == sp) { 1609 mtx_unlock(&swhash_mtx); 1610 return 1; 1611 } 1612 } 1613 } 1614 mtx_unlock(&swhash_mtx); 1615 index += SWAP_META_PAGES; 1616 if (index > 0x20000000) 1617 panic("swap_pager_isswapped: failed to locate all swap meta blocks"); 1618 } 1619 return 0; 1620 } 1621 1622 /* 1623 * SWP_PAGER_FORCE_PAGEIN() - force a swap block to be paged in 1624 * 1625 * This routine dissociates the page at the given index within a 1626 * swap block from its backing store, paging it in if necessary. 1627 * If the page is paged in, it is placed in the inactive queue, 1628 * since it had its backing store ripped out from under it. 1629 * We also attempt to swap in all other pages in the swap block, 1630 * we only guarantee that the one at the specified index is 1631 * paged in. 1632 * 1633 * XXX - The code to page the whole block in doesn't work, so we 1634 * revert to the one-by-one behavior for now. Sigh. 1635 */ 1636 static __inline void 1637 swp_pager_force_pagein(struct swblock *swap, int idx) 1638 { 1639 vm_object_t object; 1640 vm_page_t m; 1641 vm_pindex_t pindex; 1642 1643 object = swap->swb_object; 1644 pindex = swap->swb_index; 1645 mtx_unlock(&swhash_mtx); 1646 1647 VM_OBJECT_LOCK(object); 1648 vm_object_pip_add(object, 1); 1649 m = vm_page_grab(object, pindex + idx, VM_ALLOC_NORMAL|VM_ALLOC_RETRY); 1650 if (m->valid == VM_PAGE_BITS_ALL) { 1651 vm_object_pip_subtract(object, 1); 1652 vm_page_lock_queues(); 1653 vm_page_activate(m); 1654 vm_page_dirty(m); 1655 vm_page_wakeup(m); 1656 vm_page_unlock_queues(); 1657 vm_pager_page_unswapped(m); 1658 VM_OBJECT_UNLOCK(object); 1659 return; 1660 } 1661 1662 if (swap_pager_getpages(object, &m, 1, 0) != 1663 VM_PAGER_OK) 1664 panic("swap_pager_force_pagein: read from swap failed");/*XXX*/ 1665 vm_object_pip_subtract(object, 1); 1666 vm_page_lock_queues(); 1667 vm_page_dirty(m); 1668 vm_page_dontneed(m); 1669 vm_page_wakeup(m); 1670 vm_page_unlock_queues(); 1671 vm_pager_page_unswapped(m); 1672 VM_OBJECT_UNLOCK(object); 1673 } 1674 1675 1676 /* 1677 * swap_pager_swapoff: 1678 * 1679 * Page in all of the pages that have been paged out to the 1680 * given device. The corresponding blocks in the bitmap must be 1681 * marked as allocated and the device must be flagged SW_CLOSING. 1682 * There may be no processes swapped out to the device. 1683 * 1684 * The sw_used parameter points to the field in the swdev structure 1685 * that contains a count of the number of blocks still allocated 1686 * on the device. If we encounter objects with a nonzero pip count 1687 * in our scan, we use this number to determine if we're really done. 1688 * 1689 * This routine may block. 1690 */ 1691 static void 1692 swap_pager_swapoff(struct swdevt *sp, int *sw_used) 1693 { 1694 struct swblock **pswap; 1695 struct swblock *swap; 1696 vm_object_t waitobj; 1697 daddr_t v; 1698 int i, j; 1699 1700 GIANT_REQUIRED; 1701 1702 full_rescan: 1703 waitobj = NULL; 1704 for (i = 0; i <= swhash_mask; i++) { /* '<=' is correct here */ 1705 restart: 1706 pswap = &swhash[i]; 1707 mtx_lock(&swhash_mtx); 1708 while ((swap = *pswap) != NULL) { 1709 for (j = 0; j < SWAP_META_PAGES; ++j) { 1710 v = swap->swb_pages[j]; 1711 if (v != SWAPBLK_NONE && 1712 swp_pager_find_dev(v) == sp) 1713 break; 1714 } 1715 if (j < SWAP_META_PAGES) { 1716 swp_pager_force_pagein(swap, j); 1717 goto restart; 1718 } else if (swap->swb_object->paging_in_progress) { 1719 if (!waitobj) 1720 waitobj = swap->swb_object; 1721 } 1722 pswap = &swap->swb_hnext; 1723 } 1724 mtx_unlock(&swhash_mtx); 1725 } 1726 if (waitobj && *sw_used) { 1727 /* 1728 * We wait on an arbitrary object to clock our rescans 1729 * to the rate of paging completion. 1730 */ 1731 VM_OBJECT_LOCK(waitobj); 1732 vm_object_pip_wait(waitobj, "swpoff"); 1733 VM_OBJECT_UNLOCK(waitobj); 1734 goto full_rescan; 1735 } 1736 if (*sw_used) 1737 panic("swapoff: failed to locate %d swap blocks", *sw_used); 1738 } 1739 1740 /************************************************************************ 1741 * SWAP META DATA * 1742 ************************************************************************ 1743 * 1744 * These routines manipulate the swap metadata stored in the 1745 * OBJT_SWAP object. All swp_*() routines must be called at 1746 * splvm() because swap can be freed up by the low level vm_page 1747 * code which might be called from interrupts beyond what splbio() covers. 1748 * 1749 * Swap metadata is implemented with a global hash and not directly 1750 * linked into the object. Instead the object simply contains 1751 * appropriate tracking counters. 1752 */ 1753 1754 /* 1755 * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object 1756 * 1757 * We first convert the object to a swap object if it is a default 1758 * object. 1759 * 1760 * The specified swapblk is added to the object's swap metadata. If 1761 * the swapblk is not valid, it is freed instead. Any previously 1762 * assigned swapblk is freed. 1763 * 1764 * This routine must be called at splvm(), except when used to convert 1765 * an OBJT_DEFAULT object into an OBJT_SWAP object. 1766 */ 1767 static void 1768 swp_pager_meta_build(vm_object_t object, vm_pindex_t pindex, daddr_t swapblk) 1769 { 1770 struct swblock *swap; 1771 struct swblock **pswap; 1772 int idx; 1773 1774 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1775 /* 1776 * Convert default object to swap object if necessary 1777 */ 1778 if (object->type != OBJT_SWAP) { 1779 object->type = OBJT_SWAP; 1780 object->un_pager.swp.swp_bcount = 0; 1781 1782 if (object->handle != NULL) { 1783 mtx_lock(&sw_alloc_mtx); 1784 TAILQ_INSERT_TAIL( 1785 NOBJLIST(object->handle), 1786 object, 1787 pager_object_list 1788 ); 1789 mtx_unlock(&sw_alloc_mtx); 1790 } 1791 } 1792 1793 /* 1794 * Locate hash entry. If not found create, but if we aren't adding 1795 * anything just return. If we run out of space in the map we wait 1796 * and, since the hash table may have changed, retry. 1797 */ 1798 retry: 1799 mtx_lock(&swhash_mtx); 1800 pswap = swp_pager_hash(object, pindex); 1801 1802 if ((swap = *pswap) == NULL) { 1803 int i; 1804 1805 if (swapblk == SWAPBLK_NONE) 1806 goto done; 1807 1808 swap = *pswap = uma_zalloc(swap_zone, M_NOWAIT); 1809 if (swap == NULL) { 1810 mtx_unlock(&swhash_mtx); 1811 VM_OBJECT_UNLOCK(object); 1812 VM_WAIT; 1813 VM_OBJECT_LOCK(object); 1814 goto retry; 1815 } 1816 1817 swap->swb_hnext = NULL; 1818 swap->swb_object = object; 1819 swap->swb_index = pindex & ~(vm_pindex_t)SWAP_META_MASK; 1820 swap->swb_count = 0; 1821 1822 ++object->un_pager.swp.swp_bcount; 1823 1824 for (i = 0; i < SWAP_META_PAGES; ++i) 1825 swap->swb_pages[i] = SWAPBLK_NONE; 1826 } 1827 1828 /* 1829 * Delete prior contents of metadata 1830 */ 1831 idx = pindex & SWAP_META_MASK; 1832 1833 if (swap->swb_pages[idx] != SWAPBLK_NONE) { 1834 swp_pager_freeswapspace(swap->swb_pages[idx], 1); 1835 --swap->swb_count; 1836 } 1837 1838 /* 1839 * Enter block into metadata 1840 */ 1841 swap->swb_pages[idx] = swapblk; 1842 if (swapblk != SWAPBLK_NONE) 1843 ++swap->swb_count; 1844 done: 1845 mtx_unlock(&swhash_mtx); 1846 } 1847 1848 /* 1849 * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata 1850 * 1851 * The requested range of blocks is freed, with any associated swap 1852 * returned to the swap bitmap. 1853 * 1854 * This routine will free swap metadata structures as they are cleaned 1855 * out. This routine does *NOT* operate on swap metadata associated 1856 * with resident pages. 1857 * 1858 * This routine must be called at splvm() 1859 */ 1860 static void 1861 swp_pager_meta_free(vm_object_t object, vm_pindex_t index, daddr_t count) 1862 { 1863 1864 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1865 if (object->type != OBJT_SWAP) 1866 return; 1867 1868 while (count > 0) { 1869 struct swblock **pswap; 1870 struct swblock *swap; 1871 1872 mtx_lock(&swhash_mtx); 1873 pswap = swp_pager_hash(object, index); 1874 1875 if ((swap = *pswap) != NULL) { 1876 daddr_t v = swap->swb_pages[index & SWAP_META_MASK]; 1877 1878 if (v != SWAPBLK_NONE) { 1879 swp_pager_freeswapspace(v, 1); 1880 swap->swb_pages[index & SWAP_META_MASK] = 1881 SWAPBLK_NONE; 1882 if (--swap->swb_count == 0) { 1883 *pswap = swap->swb_hnext; 1884 uma_zfree(swap_zone, swap); 1885 --object->un_pager.swp.swp_bcount; 1886 } 1887 } 1888 --count; 1889 ++index; 1890 } else { 1891 int n = SWAP_META_PAGES - (index & SWAP_META_MASK); 1892 count -= n; 1893 index += n; 1894 } 1895 mtx_unlock(&swhash_mtx); 1896 } 1897 } 1898 1899 /* 1900 * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object 1901 * 1902 * This routine locates and destroys all swap metadata associated with 1903 * an object. 1904 * 1905 * This routine must be called at splvm() 1906 */ 1907 static void 1908 swp_pager_meta_free_all(vm_object_t object) 1909 { 1910 daddr_t index = 0; 1911 1912 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1913 if (object->type != OBJT_SWAP) 1914 return; 1915 1916 while (object->un_pager.swp.swp_bcount) { 1917 struct swblock **pswap; 1918 struct swblock *swap; 1919 1920 mtx_lock(&swhash_mtx); 1921 pswap = swp_pager_hash(object, index); 1922 if ((swap = *pswap) != NULL) { 1923 int i; 1924 1925 for (i = 0; i < SWAP_META_PAGES; ++i) { 1926 daddr_t v = swap->swb_pages[i]; 1927 if (v != SWAPBLK_NONE) { 1928 --swap->swb_count; 1929 swp_pager_freeswapspace(v, 1); 1930 } 1931 } 1932 if (swap->swb_count != 0) 1933 panic("swap_pager_meta_free_all: swb_count != 0"); 1934 *pswap = swap->swb_hnext; 1935 uma_zfree(swap_zone, swap); 1936 --object->un_pager.swp.swp_bcount; 1937 } 1938 mtx_unlock(&swhash_mtx); 1939 index += SWAP_META_PAGES; 1940 if (index > 0x20000000) 1941 panic("swp_pager_meta_free_all: failed to locate all swap meta blocks"); 1942 } 1943 } 1944 1945 /* 1946 * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. 1947 * 1948 * This routine is capable of looking up, popping, or freeing 1949 * swapblk assignments in the swap meta data or in the vm_page_t. 1950 * The routine typically returns the swapblk being looked-up, or popped, 1951 * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block 1952 * was invalid. This routine will automatically free any invalid 1953 * meta-data swapblks. 1954 * 1955 * It is not possible to store invalid swapblks in the swap meta data 1956 * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking. 1957 * 1958 * When acting on a busy resident page and paging is in progress, we 1959 * have to wait until paging is complete but otherwise can act on the 1960 * busy page. 1961 * 1962 * This routine must be called at splvm(). 1963 * 1964 * SWM_FREE remove and free swap block from metadata 1965 * SWM_POP remove from meta data but do not free.. pop it out 1966 */ 1967 static daddr_t 1968 swp_pager_meta_ctl(vm_object_t object, vm_pindex_t pindex, int flags) 1969 { 1970 struct swblock **pswap; 1971 struct swblock *swap; 1972 daddr_t r1; 1973 int idx; 1974 1975 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1976 /* 1977 * The meta data only exists of the object is OBJT_SWAP 1978 * and even then might not be allocated yet. 1979 */ 1980 if (object->type != OBJT_SWAP) 1981 return (SWAPBLK_NONE); 1982 1983 r1 = SWAPBLK_NONE; 1984 mtx_lock(&swhash_mtx); 1985 pswap = swp_pager_hash(object, pindex); 1986 1987 if ((swap = *pswap) != NULL) { 1988 idx = pindex & SWAP_META_MASK; 1989 r1 = swap->swb_pages[idx]; 1990 1991 if (r1 != SWAPBLK_NONE) { 1992 if (flags & SWM_FREE) { 1993 swp_pager_freeswapspace(r1, 1); 1994 r1 = SWAPBLK_NONE; 1995 } 1996 if (flags & (SWM_FREE|SWM_POP)) { 1997 swap->swb_pages[idx] = SWAPBLK_NONE; 1998 if (--swap->swb_count == 0) { 1999 *pswap = swap->swb_hnext; 2000 uma_zfree(swap_zone, swap); 2001 --object->un_pager.swp.swp_bcount; 2002 } 2003 } 2004 } 2005 } 2006 mtx_unlock(&swhash_mtx); 2007 return (r1); 2008 } 2009 2010 /* 2011 * System call swapon(name) enables swapping on device name, 2012 * which must be in the swdevsw. Return EBUSY 2013 * if already swapping on this device. 2014 */ 2015 #ifndef _SYS_SYSPROTO_H_ 2016 struct swapon_args { 2017 char *name; 2018 }; 2019 #endif 2020 2021 /* 2022 * MPSAFE 2023 */ 2024 /* ARGSUSED */ 2025 int 2026 swapon(struct thread *td, struct swapon_args *uap) 2027 { 2028 struct vattr attr; 2029 struct vnode *vp; 2030 struct nameidata nd; 2031 int error; 2032 2033 mtx_lock(&Giant); 2034 error = suser(td); 2035 if (error) 2036 goto done2; 2037 2038 while (swdev_syscall_active) 2039 tsleep(&swdev_syscall_active, PUSER - 1, "swpon", 0); 2040 swdev_syscall_active = 1; 2041 2042 /* 2043 * Swap metadata may not fit in the KVM if we have physical 2044 * memory of >1GB. 2045 */ 2046 if (swap_zone == NULL) { 2047 error = ENOMEM; 2048 goto done; 2049 } 2050 2051 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, td); 2052 error = namei(&nd); 2053 if (error) 2054 goto done; 2055 2056 NDFREE(&nd, NDF_ONLY_PNBUF); 2057 vp = nd.ni_vp; 2058 2059 if (vn_isdisk(vp, &error)) { 2060 error = swapongeom(td, vp); 2061 } else if (vp->v_type == VREG && 2062 (vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2063 (error = VOP_GETATTR(vp, &attr, td->td_ucred, td)) == 0) { 2064 /* 2065 * Allow direct swapping to NFS regular files in the same 2066 * way that nfs_mountroot() sets up diskless swapping. 2067 */ 2068 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 2069 } 2070 2071 if (error) 2072 vrele(vp); 2073 done: 2074 swdev_syscall_active = 0; 2075 wakeup_one(&swdev_syscall_active); 2076 done2: 2077 mtx_unlock(&Giant); 2078 return (error); 2079 } 2080 2081 static void 2082 swaponsomething(struct vnode *vp, void *id, u_long nblks, sw_strategy_t *strategy, sw_close_t *close, udev_t udev) 2083 { 2084 struct swdevt *sp, *tsp; 2085 swblk_t dvbase; 2086 u_long mblocks; 2087 2088 /* 2089 * If we go beyond this, we get overflows in the radix 2090 * tree bitmap code. 2091 */ 2092 mblocks = 0x40000000 / BLIST_META_RADIX; 2093 if (nblks > mblocks) { 2094 printf("WARNING: reducing size to maximum of %lu blocks per swap unit\n", 2095 mblocks); 2096 nblks = mblocks; 2097 } 2098 /* 2099 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 2100 * First chop nblks off to page-align it, then convert. 2101 * 2102 * sw->sw_nblks is in page-sized chunks now too. 2103 */ 2104 nblks &= ~(ctodb(1) - 1); 2105 nblks = dbtoc(nblks); 2106 2107 sp = malloc(sizeof *sp, M_VMPGDATA, M_WAITOK | M_ZERO); 2108 sp->sw_vp = vp; 2109 sp->sw_id = id; 2110 sp->sw_udev = udev; 2111 sp->sw_flags = 0; 2112 sp->sw_nblks = nblks; 2113 sp->sw_used = 0; 2114 sp->sw_strategy = strategy; 2115 sp->sw_close = close; 2116 2117 sp->sw_blist = blist_create(nblks); 2118 /* 2119 * Do not free the first two block in order to avoid overwriting 2120 * any bsd label at the front of the partition 2121 */ 2122 blist_free(sp->sw_blist, 2, nblks - 2); 2123 2124 dvbase = 0; 2125 mtx_lock(&sw_dev_mtx); 2126 TAILQ_FOREACH(tsp, &swtailq, sw_list) { 2127 if (tsp->sw_end >= dvbase) { 2128 /* 2129 * We put one uncovered page between the devices 2130 * in order to definitively prevent any cross-device 2131 * I/O requests 2132 */ 2133 dvbase = tsp->sw_end + 1; 2134 } 2135 } 2136 sp->sw_first = dvbase; 2137 sp->sw_end = dvbase + nblks; 2138 TAILQ_INSERT_TAIL(&swtailq, sp, sw_list); 2139 nswapdev++; 2140 swap_pager_avail += nblks; 2141 swp_sizecheck(); 2142 mtx_unlock(&sw_dev_mtx); 2143 } 2144 2145 /* 2146 * SYSCALL: swapoff(devname) 2147 * 2148 * Disable swapping on the given device. 2149 * 2150 * XXX: Badly designed system call: it should use a device index 2151 * rather than filename as specification. We keep sw_vp around 2152 * only to make this work. 2153 */ 2154 #ifndef _SYS_SYSPROTO_H_ 2155 struct swapoff_args { 2156 char *name; 2157 }; 2158 #endif 2159 2160 /* 2161 * MPSAFE 2162 */ 2163 /* ARGSUSED */ 2164 int 2165 swapoff(struct thread *td, struct swapoff_args *uap) 2166 { 2167 struct vnode *vp; 2168 struct nameidata nd; 2169 struct swdevt *sp; 2170 u_long nblks, dvbase; 2171 int error; 2172 2173 mtx_lock(&Giant); 2174 2175 error = suser(td); 2176 if (error) 2177 goto done2; 2178 2179 while (swdev_syscall_active) 2180 tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0); 2181 swdev_syscall_active = 1; 2182 2183 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, td); 2184 error = namei(&nd); 2185 if (error) 2186 goto done; 2187 NDFREE(&nd, NDF_ONLY_PNBUF); 2188 vp = nd.ni_vp; 2189 2190 mtx_lock(&sw_dev_mtx); 2191 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2192 if (sp->sw_vp == vp) 2193 goto found; 2194 } 2195 mtx_unlock(&sw_dev_mtx); 2196 error = EINVAL; 2197 goto done; 2198 found: 2199 mtx_unlock(&sw_dev_mtx); 2200 #ifdef MAC 2201 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 2202 error = mac_check_system_swapoff(td->td_ucred, vp); 2203 (void) VOP_UNLOCK(vp, 0, td); 2204 if (error != 0) 2205 goto done; 2206 #endif 2207 2208 nblks = sp->sw_nblks; 2209 2210 /* 2211 * We can turn off this swap device safely only if the 2212 * available virtual memory in the system will fit the amount 2213 * of data we will have to page back in, plus an epsilon so 2214 * the system doesn't become critically low on swap space. 2215 */ 2216 if (cnt.v_free_count + cnt.v_cache_count + swap_pager_avail < 2217 nblks + nswap_lowat) { 2218 error = ENOMEM; 2219 goto done; 2220 } 2221 2222 /* 2223 * Prevent further allocations on this device. 2224 */ 2225 mtx_lock(&sw_dev_mtx); 2226 sp->sw_flags |= SW_CLOSING; 2227 for (dvbase = 0; dvbase < sp->sw_end; dvbase += dmmax) { 2228 swap_pager_avail -= blist_fill(sp->sw_blist, 2229 dvbase, dmmax); 2230 } 2231 mtx_unlock(&sw_dev_mtx); 2232 2233 /* 2234 * Page in the contents of the device and close it. 2235 */ 2236 #ifndef NO_SWAPPING 2237 vm_proc_swapin_all(sp); 2238 #endif /* !NO_SWAPPING */ 2239 swap_pager_swapoff(sp, &sp->sw_used); 2240 2241 sp->sw_close(td, sp); 2242 sp->sw_id = NULL; 2243 mtx_lock(&sw_dev_mtx); 2244 TAILQ_REMOVE(&swtailq, sp, sw_list); 2245 nswapdev--; 2246 if (nswapdev == 0) { 2247 swap_pager_full = 2; 2248 swap_pager_almost_full = 1; 2249 } 2250 if (swdevhd == sp) 2251 swdevhd = NULL; 2252 mtx_unlock(&sw_dev_mtx); 2253 blist_destroy(sp->sw_blist); 2254 free(sp, M_VMPGDATA); 2255 2256 done: 2257 swdev_syscall_active = 0; 2258 wakeup_one(&swdev_syscall_active); 2259 done2: 2260 mtx_unlock(&Giant); 2261 return (error); 2262 } 2263 2264 void 2265 swap_pager_status(int *total, int *used) 2266 { 2267 struct swdevt *sp; 2268 2269 *total = 0; 2270 *used = 0; 2271 mtx_lock(&sw_dev_mtx); 2272 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2273 *total += sp->sw_nblks; 2274 *used += sp->sw_used; 2275 } 2276 mtx_unlock(&sw_dev_mtx); 2277 } 2278 2279 static int 2280 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 2281 { 2282 int *name = (int *)arg1; 2283 int error, n; 2284 struct xswdev xs; 2285 struct swdevt *sp; 2286 2287 if (arg2 != 1) /* name length */ 2288 return (EINVAL); 2289 2290 n = 0; 2291 mtx_lock(&sw_dev_mtx); 2292 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2293 if (n == *name) { 2294 mtx_unlock(&sw_dev_mtx); 2295 xs.xsw_version = XSWDEV_VERSION; 2296 xs.xsw_dev = sp->sw_udev; 2297 xs.xsw_flags = sp->sw_flags; 2298 xs.xsw_nblks = sp->sw_nblks; 2299 xs.xsw_used = sp->sw_used; 2300 2301 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 2302 return (error); 2303 } 2304 n++; 2305 } 2306 mtx_unlock(&sw_dev_mtx); 2307 return (ENOENT); 2308 } 2309 2310 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswapdev, 0, 2311 "Number of swap devices"); 2312 SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD, sysctl_vm_swap_info, 2313 "Swap statistics by device"); 2314 2315 /* 2316 * vmspace_swap_count() - count the approximate swap useage in pages for a 2317 * vmspace. 2318 * 2319 * The map must be locked. 2320 * 2321 * Swap useage is determined by taking the proportional swap used by 2322 * VM objects backing the VM map. To make up for fractional losses, 2323 * if the VM object has any swap use at all the associated map entries 2324 * count for at least 1 swap page. 2325 */ 2326 int 2327 vmspace_swap_count(struct vmspace *vmspace) 2328 { 2329 vm_map_t map = &vmspace->vm_map; 2330 vm_map_entry_t cur; 2331 int count = 0; 2332 2333 for (cur = map->header.next; cur != &map->header; cur = cur->next) { 2334 vm_object_t object; 2335 2336 if ((cur->eflags & MAP_ENTRY_IS_SUB_MAP) == 0 && 2337 (object = cur->object.vm_object) != NULL) { 2338 VM_OBJECT_LOCK(object); 2339 if (object->type == OBJT_SWAP && 2340 object->un_pager.swp.swp_bcount != 0) { 2341 int n = (cur->end - cur->start) / PAGE_SIZE; 2342 2343 count += object->un_pager.swp.swp_bcount * 2344 SWAP_META_PAGES * n / object->size + 1; 2345 } 2346 VM_OBJECT_UNLOCK(object); 2347 } 2348 } 2349 return (count); 2350 } 2351 2352 /* 2353 * GEOM backend 2354 * 2355 * Swapping onto disk devices. 2356 * 2357 */ 2358 2359 static struct g_class g_swap_class = { 2360 .name = "SWAP", 2361 }; 2362 2363 DECLARE_GEOM_CLASS(g_swap_class, g_class); 2364 2365 2366 static void 2367 swapgeom_done(struct bio *bp2) 2368 { 2369 struct buf *bp; 2370 2371 bp = bp2->bio_caller2; 2372 if (bp2->bio_error) 2373 bp->b_ioflags |= BIO_ERROR; 2374 bufdone(bp); 2375 g_destroy_bio(bp2); 2376 } 2377 2378 static void 2379 swapgeom_strategy(struct buf *bp, struct swdevt *sp) 2380 { 2381 struct bio *bio; 2382 struct g_consumer *cp; 2383 2384 cp = sp->sw_id; 2385 if (cp == NULL) { 2386 bp->b_error = ENXIO; 2387 bp->b_ioflags |= BIO_ERROR; 2388 bufdone(bp); 2389 return; 2390 } 2391 bio = g_clone_bio(&bp->b_io); 2392 if (bio == NULL) { 2393 /* 2394 * XXX: This is better than panicing, but not much better. 2395 * XXX: Somehow this should be retried. A more generic 2396 * XXX: implementation of ENOMEM in geom may be able to cope. 2397 */ 2398 bp->b_error = ENOMEM; 2399 bp->b_ioflags |= BIO_ERROR; 2400 bufdone(bp); 2401 return; 2402 } 2403 bio->bio_caller2 = bp; 2404 bio->bio_offset = (bp->b_blkno - sp->sw_first) * PAGE_SIZE; 2405 bio->bio_length = bp->b_bcount; 2406 bio->bio_done = swapgeom_done; 2407 g_io_request(bio, cp); 2408 return; 2409 } 2410 2411 static void 2412 swapgeom_orphan(struct g_consumer *cp) 2413 { 2414 struct swdevt *sp; 2415 2416 mtx_lock(&sw_dev_mtx); 2417 TAILQ_FOREACH(sp, &swtailq, sw_list) 2418 if (sp->sw_id == cp) 2419 sp->sw_id = NULL; 2420 mtx_unlock(&sw_dev_mtx); 2421 } 2422 2423 static void 2424 swapgeom_close_ev(void *arg, int flags) 2425 { 2426 struct g_consumer *cp; 2427 2428 cp = arg; 2429 g_access(cp, -1, -1, 0); 2430 g_detach(cp); 2431 g_destroy_consumer(cp); 2432 } 2433 2434 static void 2435 swapgeom_close(struct thread *td, struct swdevt *sw) 2436 { 2437 2438 /* XXX: direct call when Giant untangled */ 2439 g_waitfor_event(swapgeom_close_ev, sw->sw_id, M_WAITOK, NULL); 2440 } 2441 2442 2443 struct swh0h0 { 2444 dev_t dev; 2445 struct vnode *vp; 2446 int error; 2447 }; 2448 2449 static void 2450 swapongeom_ev(void *arg, int flags) 2451 { 2452 struct swh0h0 *swh; 2453 struct g_provider *pp; 2454 struct g_consumer *cp; 2455 static struct g_geom *gp; 2456 struct swdevt *sp; 2457 u_long nblks; 2458 int error; 2459 2460 swh = arg; 2461 swh->error = 0; 2462 pp = g_dev_getprovider(swh->dev); 2463 if (pp == NULL) { 2464 swh->error = ENODEV; 2465 return; 2466 } 2467 mtx_lock(&sw_dev_mtx); 2468 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2469 cp = sp->sw_id; 2470 if (cp != NULL && cp->provider == pp) { 2471 mtx_unlock(&sw_dev_mtx); 2472 swh->error = EBUSY; 2473 return; 2474 } 2475 } 2476 mtx_unlock(&sw_dev_mtx); 2477 if (gp == NULL) { 2478 gp = g_new_geomf(&g_swap_class, "swap", NULL); 2479 gp->orphan = swapgeom_orphan; 2480 } 2481 cp = g_new_consumer(gp); 2482 g_attach(cp, pp); 2483 /* 2484 * XXX: Everytime you think you can improve the margin for 2485 * footshooting, somebody depends on the ability to do so: 2486 * savecore(8) wants to write to our swapdev so we cannot 2487 * set an exclusive count :-( 2488 */ 2489 error = g_access(cp, 1, 1, 0); 2490 if (error) { 2491 g_detach(cp); 2492 g_destroy_consumer(cp); 2493 swh->error = error; 2494 return; 2495 } 2496 nblks = pp->mediasize / DEV_BSIZE; 2497 swaponsomething(swh->vp, cp, nblks, swapgeom_strategy, 2498 swapgeom_close, dev2udev(swh->dev)); 2499 swh->error = 0; 2500 return; 2501 } 2502 2503 static int 2504 swapongeom(struct thread *td, struct vnode *vp) 2505 { 2506 int error; 2507 struct swh0h0 swh; 2508 2509 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 2510 2511 swh.dev = vp->v_rdev; 2512 swh.vp = vp; 2513 swh.error = 0; 2514 /* XXX: direct call when Giant untangled */ 2515 error = g_waitfor_event(swapongeom_ev, &swh, M_WAITOK, NULL); 2516 if (!error) 2517 error = swh.error; 2518 VOP_UNLOCK(vp, 0, td); 2519 return (error); 2520 } 2521 2522 /* 2523 * VNODE backend 2524 * 2525 * This is used mainly for network filesystem (read: probably only tested 2526 * with NFS) swapfiles. 2527 * 2528 */ 2529 2530 static void 2531 swapdev_strategy(struct buf *bp, struct swdevt *sp) 2532 { 2533 int s; 2534 struct vnode *vp, *vp2; 2535 2536 bp->b_dev = NODEV; 2537 bp->b_blkno = ctodb(bp->b_blkno - sp->sw_first); 2538 2539 vp2 = sp->sw_id; 2540 vhold(vp2); 2541 s = splvm(); 2542 if (bp->b_iocmd == BIO_WRITE) { 2543 vp = bp->b_vp; 2544 if (vp) { 2545 VI_LOCK(vp); 2546 vp->v_numoutput--; 2547 if ((vp->v_iflag & VI_BWAIT) && vp->v_numoutput <= 0) { 2548 vp->v_iflag &= ~VI_BWAIT; 2549 wakeup(&vp->v_numoutput); 2550 } 2551 VI_UNLOCK(vp); 2552 } 2553 VI_LOCK(vp2); 2554 vp2->v_numoutput++; 2555 VI_UNLOCK(vp2); 2556 } 2557 bp->b_vp = vp2; 2558 splx(s); 2559 bp->b_iooffset = dbtob(bp->b_blkno); 2560 VOP_STRATEGY(vp2, bp); 2561 return; 2562 } 2563 2564 static void 2565 swapdev_close(struct thread *td, struct swdevt *sp) 2566 { 2567 2568 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, td->td_ucred, td); 2569 vrele(sp->sw_vp); 2570 } 2571 2572 2573 static int 2574 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 2575 { 2576 struct swdevt *sp; 2577 int error; 2578 2579 if (nblks == 0) 2580 return (ENXIO); 2581 mtx_lock(&sw_dev_mtx); 2582 TAILQ_FOREACH(sp, &swtailq, sw_list) { 2583 if (sp->sw_id == vp) { 2584 mtx_unlock(&sw_dev_mtx); 2585 return (EBUSY); 2586 } 2587 } 2588 mtx_unlock(&sw_dev_mtx); 2589 2590 (void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 2591 #ifdef MAC 2592 error = mac_check_system_swapon(td->td_ucred, vp); 2593 if (error == 0) 2594 #endif 2595 error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td, -1); 2596 (void) VOP_UNLOCK(vp, 0, td); 2597 if (error) 2598 return (error); 2599 2600 swaponsomething(vp, vp, nblks, swapdev_strategy, swapdev_close, 2601 NOUDEV); 2602 return (0); 2603 } 2604