1 /* 2 * (MPSAFE) 3 * 4 * Copyright (c) 1982, 1986, 1989, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * @(#)vm_swap.c 8.5 (Berkeley) 2/17/94 32 * $FreeBSD: src/sys/vm/vm_swap.c,v 1.96.2.2 2001/10/14 18:46:47 iedowse Exp $ 33 */ 34 35 #include "opt_swap.h" 36 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/sysmsg.h> 40 #include <sys/buf.h> 41 #include <sys/proc.h> 42 #include <sys/priv.h> 43 #include <sys/nlookup.h> 44 #include <sys/sysctl.h> 45 #include <sys/dmap.h> /* XXX */ 46 #include <sys/vnode.h> 47 #include <sys/fcntl.h> 48 #include <sys/blist.h> 49 #include <sys/kernel.h> 50 #include <sys/lock.h> 51 #include <sys/conf.h> 52 #include <sys/stat.h> 53 54 #include <vm/vm.h> 55 #include <vm/vm_extern.h> 56 #include <vm/swap_pager.h> 57 #include <vm/vm_zone.h> 58 #include <vm/vm_param.h> 59 60 #include <sys/mutex2.h> 61 #include <sys/spinlock2.h> 62 63 /* 64 * Indirect driver for multi-controller paging. 65 */ 66 67 #ifndef NSWAPDEV 68 #define NSWAPDEV 4 69 #endif 70 static struct swdevt should_be_malloced[NSWAPDEV]; 71 struct swdevt *swdevt = should_be_malloced; /* exported to pstat/systat */ 72 static swblk_t nswap; /* first block after the interleaved devs */ 73 static struct mtx swap_mtx = MTX_INITIALIZER("swpmtx"); 74 int nswdev = NSWAPDEV; /* exported to pstat/systat */ 75 swblk_t vm_swap_size; 76 swblk_t vm_swap_max; 77 78 static int swapoff_one(int index); 79 struct vnode *swapdev_vp; 80 81 /* 82 * (struct vnode *a_vp, struct bio *b_bio) 83 * 84 * vn_strategy() for swapdev_vp. Perform swap strategy interleave device 85 * selection. 86 * 87 * This function supports the KVABIO API. If the underlying vnode/device 88 * does not, it will make appropriate adjustments. 89 * 90 * No requirements. 91 */ 92 static int 93 swapdev_strategy(struct vop_strategy_args *ap) 94 { 95 struct bio *bio = ap->a_bio; 96 struct bio *nbio; 97 struct buf *bp = bio->bio_buf; 98 swblk_t sz, off, seg, blkno, nblkno; 99 int index; 100 struct swdevt *sp; 101 sz = howmany(bp->b_bcount, PAGE_SIZE); 102 blkno = (swblk_t)(bio->bio_offset >> PAGE_SHIFT); 103 104 /* 105 * Convert interleaved swap into per-device swap. Note that 106 * the block size is left in PAGE_SIZE'd chunks (for the newswap) 107 * here. 108 */ 109 nbio = push_bio(bio); 110 if (nswdev > 1) { 111 off = blkno % SWB_DMMAX; 112 if (off + sz > SWB_DMMAX) { 113 bp->b_error = EINVAL; 114 bp->b_flags |= B_ERROR; 115 biodone(bio); 116 return 0; 117 } 118 seg = blkno / SWB_DMMAX; 119 index = seg % nswdev; 120 seg /= nswdev; 121 nbio->bio_offset = (off_t)(seg * SWB_DMMAX + off) << PAGE_SHIFT; 122 } else { 123 index = 0; 124 nbio->bio_offset = bio->bio_offset; 125 } 126 nblkno = (swblk_t)(nbio->bio_offset >> PAGE_SHIFT); 127 sp = &swdevt[index]; 128 if (nblkno + sz > sp->sw_nblks) { 129 bp->b_error = EINVAL; 130 bp->b_flags |= B_ERROR; 131 /* I/O was never started on nbio, must biodone(bio) */ 132 biodone(bio); 133 return 0; 134 } 135 if (sp->sw_vp == NULL) { 136 bp->b_error = ENODEV; 137 bp->b_flags |= B_ERROR; 138 /* I/O was never started on nbio, must biodone(bio) */ 139 biodone(bio); 140 return 0; 141 } 142 143 /* 144 * Issue a strategy call on the appropriate swap vnode. Note that 145 * bp->b_vp is not modified. Strategy code is always supposed to 146 * use the passed vp. 147 * 148 * We have to use vn_strategy() here even if we know we have a 149 * device in order to properly break up requests which exceed the 150 * device's DMA limits. 151 */ 152 vn_strategy(sp->sw_vp, nbio); 153 154 return 0; 155 } 156 157 static int 158 swapdev_inactive(struct vop_inactive_args *ap) 159 { 160 vrecycle(ap->a_vp); 161 return(0); 162 } 163 164 static int 165 swapdev_reclaim(struct vop_reclaim_args *ap) 166 { 167 return(0); 168 } 169 170 /* 171 * Create a special vnode op vector for swapdev_vp - we only use 172 * vn_strategy(), everything else returns an error. 173 */ 174 static struct vop_ops swapdev_vnode_vops = { 175 .vop_default = vop_defaultop, 176 .vop_strategy = swapdev_strategy, 177 .vop_inactive = swapdev_inactive, 178 .vop_reclaim = swapdev_reclaim 179 }; 180 static struct vop_ops *swapdev_vnode_vops_p = &swapdev_vnode_vops; 181 182 VNODEOP_SET(swapdev_vnode_vops); 183 184 /* 185 * swapon_args(char *name) 186 * 187 * System call swapon(name) enables swapping on device name, 188 * which must be in the swdevsw. Return EBUSY 189 * if already swapping on this device. 190 * 191 * No requirements. 192 */ 193 int 194 sys_swapon(struct sysmsg *sysmsg, const struct swapon_args *uap) 195 { 196 struct thread *td = curthread; 197 struct vattr attr; 198 struct vnode *vp; 199 struct nlookupdata nd; 200 int error; 201 202 error = priv_check(td, PRIV_ROOT); 203 if (error) 204 return (error); 205 206 mtx_lock(&swap_mtx); 207 vp = NULL; 208 error = nlookup_init(&nd, uap->name, UIO_USERSPACE, NLC_FOLLOW); 209 if (error == 0) 210 error = nlookup(&nd); 211 if (error == 0) 212 error = cache_vref(&nd.nl_nch, nd.nl_cred, &vp); 213 nlookup_done(&nd); 214 if (error) { 215 mtx_unlock(&swap_mtx); 216 return (error); 217 } 218 219 if (vn_isdisk(vp, &error)) { 220 error = swaponvp(td, vp, 0); 221 } else if (vp->v_type == VREG && vp->v_tag == VT_NFS && 222 (error = VOP_GETATTR(vp, &attr)) == 0) { 223 /* 224 * Allow direct swapping to NFS regular files in the same 225 * way that nfs_mountroot() sets up diskless swapping. 226 */ 227 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 228 } 229 if (error) 230 vrele(vp); 231 mtx_unlock(&swap_mtx); 232 233 return (error); 234 } 235 236 /* 237 * Swfree(index) frees the index'th portion of the swap map. 238 * Each of the nswdev devices provides 1/nswdev'th of the swap 239 * space, which is laid out with blocks of SWB_DMMAX pages circularly 240 * among the devices. 241 * 242 * The new swap code uses page-sized blocks. The old swap code used 243 * DEV_BSIZE'd chunks. 244 * 245 * XXX locking when multiple swapon's run in parallel 246 */ 247 int 248 swaponvp(struct thread *td, struct vnode *vp, u_quad_t nblks) 249 { 250 swblk_t aligned_nblks; 251 int64_t dpsize; 252 struct ucred *cred; 253 struct swdevt *sp; 254 swblk_t vsbase; 255 swblk_t dvbase; 256 cdev_t dev; 257 int index; 258 int error; 259 swblk_t blk; 260 261 cred = td->td_ucred; 262 263 lwkt_gettoken(&vm_token); /* needed for vm_swap_size and blist */ 264 mtx_lock(&swap_mtx); 265 266 /* 267 * Setup swapdev_vp. We support the KVABIO API for this vnode's 268 * strategy function. 269 */ 270 if (!swapdev_vp) { 271 error = getspecialvnode(VT_NON, NULL, &swapdev_vnode_vops_p, 272 &swapdev_vp, 0, 0); 273 if (error) 274 panic("Cannot get vnode for swapdev"); 275 swapdev_vp->v_type = VNON; /* Untyped */ 276 vsetflags(swapdev_vp, VKVABIO); 277 vx_unlock(swapdev_vp); 278 } 279 280 for (sp = swdevt, index = 0 ; index < nswdev; index++, sp++) { 281 if (sp->sw_vp == vp) { 282 error = EBUSY; 283 goto done; 284 } 285 if (!sp->sw_vp) 286 goto found; 287 288 } 289 error = EINVAL; 290 goto done; 291 found: 292 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 293 error = VOP_OPEN(vp, FREAD | FWRITE, cred, NULL); 294 vn_unlock(vp); 295 if (error) 296 goto done; 297 298 /* 299 * v_rdev is not valid until after the VOP_OPEN() call. dev_psize() 300 * must be supported if a character device has been specified. 301 */ 302 if (vp->v_type == VCHR) 303 dev = vp->v_rdev; 304 else 305 dev = NULL; 306 307 if (nblks == 0 && dev != NULL) { 308 dpsize = dev_dpsize(dev); 309 if (dpsize == -1) { 310 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 311 VOP_CLOSE(vp, FREAD | FWRITE, NULL); 312 vn_unlock(vp); 313 error = ENXIO; 314 goto done; 315 } 316 nblks = (u_quad_t)dpsize; 317 } 318 if (nblks == 0) { 319 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 320 VOP_CLOSE(vp, FREAD | FWRITE, NULL); 321 vn_unlock(vp); 322 error = ENXIO; 323 goto done; 324 } 325 326 /* 327 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 328 * First chop nblks off to page-align it, then convert. 329 * 330 * sw->sw_nblks is in page-sized chunks now too. 331 */ 332 nblks &= ~(u_quad_t)(ctodb(1) - 1); 333 nblks = dbtoc(nblks); 334 335 /* 336 * Post-conversion nblks must not be >= BLIST_MAXBLKS, and 337 * we impose a 4-swap-device limit so we have to divide it out 338 * further. Going beyond this will result in overflows in the 339 * blist code. 340 * 341 * Post-conversion nblks must fit within a (swblk_t), which 342 * this test also ensures. 343 */ 344 if (nblks > BLIST_MAXBLKS / nswdev) { 345 kprintf("exceeded maximum of %ld blocks per swap unit\n", 346 (long)BLIST_MAXBLKS / nswdev); 347 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 348 VOP_CLOSE(vp, FREAD | FWRITE, NULL); 349 vn_unlock(vp); 350 error = ENXIO; 351 goto done; 352 } 353 354 sp->sw_vp = vp; 355 sp->sw_dev = devid_from_dev(dev); 356 sp->sw_device = dev; 357 sp->sw_flags = SW_FREED; 358 sp->sw_nused = 0; 359 360 /* 361 * nblks, nswap, and SWB_DMMAX are PAGE_SIZE'd parameters now, not 362 * DEV_BSIZE'd. aligned_nblks is used to calculate the 363 * size of the swap bitmap, taking into account the stripe size. 364 */ 365 aligned_nblks = (swblk_t)((nblks + SWB_DMMASK) & 366 ~(u_swblk_t)SWB_DMMASK); 367 sp->sw_nblks = aligned_nblks; 368 369 if (aligned_nblks * nswdev > nswap) 370 nswap = aligned_nblks * nswdev; 371 372 if (swapblist == NULL) 373 swapblist = blist_create(nswap); 374 else 375 blist_resize(&swapblist, nswap, 0); 376 377 for (dvbase = SWB_DMMAX; dvbase < aligned_nblks; dvbase += SWB_DMMAX) { 378 blk = min(aligned_nblks - dvbase, SWB_DMMAX); 379 vsbase = index * SWB_DMMAX + dvbase * nswdev; 380 blist_free(swapblist, vsbase, blk); 381 vm_swap_size += blk; 382 vm_swap_max += blk; 383 } 384 swap_pager_newswap(); 385 error = 0; 386 done: 387 mtx_unlock(&swap_mtx); 388 lwkt_reltoken(&vm_token); 389 return (error); 390 } 391 392 /* 393 * swapoff_args(char *name) 394 * 395 * System call swapoff(name) disables swapping on device name, 396 * which must be an active swap device. Return ENOMEM 397 * if there is not enough memory to page in the contents of 398 * the given device. 399 * 400 * No requirements. 401 */ 402 int 403 sys_swapoff(struct sysmsg *sysmsg, const struct swapoff_args *uap) 404 { 405 struct vnode *vp; 406 struct nlookupdata nd; 407 struct swdevt *sp; 408 int error, index; 409 410 error = priv_check(curthread, PRIV_ROOT); 411 if (error) 412 return (error); 413 414 mtx_lock(&swap_mtx); 415 vp = NULL; 416 error = nlookup_init(&nd, uap->name, UIO_USERSPACE, NLC_FOLLOW); 417 if (error == 0) 418 error = nlookup(&nd); 419 if (error == 0) 420 error = cache_vref(&nd.nl_nch, nd.nl_cred, &vp); 421 nlookup_done(&nd); 422 if (error) 423 goto done; 424 425 for (sp = swdevt, index = 0; index < nswdev; index++, sp++) { 426 if (sp->sw_vp == vp) 427 goto found; 428 } 429 error = EINVAL; 430 goto done; 431 found: 432 error = swapoff_one(index); 433 swap_pager_newswap(); 434 435 done: 436 mtx_unlock(&swap_mtx); 437 return (error); 438 } 439 440 static int 441 swapoff_one(int index) 442 { 443 swblk_t blk, aligned_nblks; 444 swblk_t dvbase, vsbase; 445 u_int pq_active_clean, pq_inactive_clean; 446 struct swdevt *sp; 447 struct vm_page marker; 448 vm_page_t m; 449 int q; 450 451 mtx_lock(&swap_mtx); 452 453 sp = &swdevt[index]; 454 aligned_nblks = sp->sw_nblks; 455 pq_active_clean = pq_inactive_clean = 0; 456 457 /* 458 * We can turn off this swap device safely only if the 459 * available virtual memory in the system will fit the amount 460 * of data we will have to page back in, plus an epsilon so 461 * the system doesn't become critically low on swap space. 462 */ 463 for (q = 0; q < PQ_L2_SIZE; ++q) { 464 bzero(&marker, sizeof(marker)); 465 marker.flags = PG_FICTITIOUS | PG_MARKER; 466 marker.busy_count = PBUSY_LOCKED; 467 marker.queue = PQ_ACTIVE + q; 468 marker.pc = q; 469 marker.wire_count = 1; 470 471 vm_page_queues_spin_lock(marker.queue); 472 TAILQ_INSERT_HEAD(&vm_page_queues[marker.queue].pl, 473 &marker, pageq); 474 475 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL) { 476 TAILQ_REMOVE(&vm_page_queues[marker.queue].pl, 477 &marker, pageq); 478 TAILQ_INSERT_AFTER(&vm_page_queues[marker.queue].pl, m, 479 &marker, pageq); 480 if (m->flags & (PG_MARKER | PG_FICTITIOUS)) 481 continue; 482 483 if (vm_page_busy_try(m, FALSE) == 0) { 484 vm_page_queues_spin_unlock(marker.queue); 485 if (m->dirty == 0) { 486 vm_page_test_dirty(m); 487 if (m->dirty == 0) 488 ++pq_active_clean; 489 } 490 vm_page_wakeup(m); 491 vm_page_queues_spin_lock(marker.queue); 492 } 493 } 494 TAILQ_REMOVE(&vm_page_queues[marker.queue].pl, &marker, pageq); 495 vm_page_queues_spin_unlock(marker.queue); 496 497 marker.queue = PQ_INACTIVE + q; 498 marker.pc = q; 499 vm_page_queues_spin_lock(marker.queue); 500 TAILQ_INSERT_HEAD(&vm_page_queues[marker.queue].pl, 501 &marker, pageq); 502 503 while ((m = TAILQ_NEXT(&marker, pageq)) != NULL) { 504 TAILQ_REMOVE( 505 &vm_page_queues[marker.queue].pl, 506 &marker, pageq); 507 TAILQ_INSERT_AFTER( 508 &vm_page_queues[marker.queue].pl, 509 m, &marker, pageq); 510 if (m->flags & (PG_MARKER | PG_FICTITIOUS)) 511 continue; 512 513 if (vm_page_busy_try(m, FALSE) == 0) { 514 vm_page_queues_spin_unlock(marker.queue); 515 if (m->dirty == 0) { 516 vm_page_test_dirty(m); 517 if (m->dirty == 0) 518 ++pq_inactive_clean; 519 } 520 vm_page_wakeup(m); 521 vm_page_queues_spin_lock(marker.queue); 522 } 523 } 524 TAILQ_REMOVE(&vm_page_queues[marker.queue].pl, 525 &marker, pageq); 526 vm_page_queues_spin_unlock(marker.queue); 527 } 528 529 if (vmstats.v_free_count + vmstats.v_cache_count + pq_active_clean + 530 pq_inactive_clean + vm_swap_size < aligned_nblks + nswap_lowat) { 531 mtx_unlock(&swap_mtx); 532 return (ENOMEM); 533 } 534 535 /* 536 * Prevent further allocations on this device 537 */ 538 sp->sw_flags |= SW_CLOSING; 539 for (dvbase = SWB_DMMAX; dvbase < aligned_nblks; dvbase += SWB_DMMAX) { 540 blk = min(aligned_nblks - dvbase, SWB_DMMAX); 541 vsbase = index * SWB_DMMAX + dvbase * nswdev; 542 vm_swap_size -= blist_fill(swapblist, vsbase, blk); 543 vm_swap_max -= blk; 544 } 545 546 /* 547 * Page in the contents of the device and close it. 548 */ 549 if (swap_pager_swapoff(index) && swap_pager_swapoff(index)) { 550 mtx_unlock(&swap_mtx); 551 return (EINTR); 552 } 553 554 vn_lock(sp->sw_vp, LK_EXCLUSIVE | LK_RETRY); 555 VOP_CLOSE(sp->sw_vp, FREAD | FWRITE, NULL); 556 vn_unlock(sp->sw_vp); 557 vrele(sp->sw_vp); 558 bzero(swdevt + index, sizeof(struct swdevt)); 559 560 /* 561 * Resize the bitmap based on the nem largest swap device, 562 * or free the bitmap if there are no more devices. 563 */ 564 for (sp = swdevt, aligned_nblks = 0; sp < swdevt + nswdev; sp++) { 565 if (sp->sw_vp) 566 aligned_nblks = max(aligned_nblks, sp->sw_nblks); 567 } 568 569 nswap = aligned_nblks * nswdev; 570 571 if (nswap == 0) { 572 blist_destroy(swapblist); 573 swapblist = NULL; 574 vrele(swapdev_vp); 575 swapdev_vp = NULL; 576 } else { 577 blist_resize(&swapblist, nswap, 0); 578 } 579 580 mtx_unlock(&swap_mtx); 581 return (0); 582 } 583 584 /* 585 * Account for swap space in individual swdevt's. The caller ensures 586 * that the provided range falls into a single swdevt. 587 * 588 * +count space freed 589 * -count space allocated 590 */ 591 void 592 swapacctspace(swblk_t base, swblk_t count) 593 { 594 int index; 595 swblk_t seg; 596 597 vm_swap_size += count; 598 seg = base / SWB_DMMAX; 599 index = seg % nswdev; 600 swdevt[index].sw_nused -= count; 601 } 602 603 /* 604 * Retrieve swap info 605 */ 606 static int 607 sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS) 608 { 609 struct xswdev xs; 610 struct swdevt *sp; 611 int error; 612 int n; 613 614 error = 0; 615 for (n = 0; n < nswdev; ++n) { 616 sp = &swdevt[n]; 617 618 xs.xsw_size = sizeof(xs); 619 xs.xsw_version = XSWDEV_VERSION; 620 xs.xsw_blksize = PAGE_SIZE; 621 xs.xsw_dev = sp->sw_dev; 622 xs.xsw_flags = sp->sw_flags; 623 xs.xsw_nblks = sp->sw_nblks; 624 xs.xsw_used = sp->sw_nused; 625 626 error = SYSCTL_OUT(req, &xs, sizeof(xs)); 627 if (error) 628 break; 629 } 630 return (error); 631 } 632 633 SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswdev, 0, 634 "Number of swap devices"); 635 SYSCTL_NODE(_vm, OID_AUTO, swap_info_array, CTLFLAG_RD, sysctl_vm_swap_info, 636 "Swap statistics by device"); 637