| 1 | /* |
| 2 | * Copyright (c) 1998,2004 The DragonFly Project. All rights reserved. |
| 3 | * |
| 4 | * This code is derived from software contributed to The DragonFly Project |
| 5 | * by Matthew Dillon <dillon@backplane.com> |
| 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 | * |
| 11 | * 1. Redistributions of source code must retain the above copyright |
| 12 | * notice, this list of conditions and the following disclaimer. |
| 13 | * 2. Redistributions in binary form must reproduce the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer in |
| 15 | * the documentation and/or other materials provided with the |
| 16 | * distribution. |
| 17 | * 3. Neither the name of The DragonFly Project nor the names of its |
| 18 | * contributors may be used to endorse or promote products derived |
| 19 | * from this software without specific, prior written permission. |
| 20 | * |
| 21 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 22 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 23 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| 24 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| 25 | * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 26 | * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, |
| 27 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| 28 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
| 29 | * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| 30 | * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| 31 | * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 32 | * SUCH DAMAGE. |
| 33 | * |
| 34 | * Copyright (c) 1994 John S. Dyson |
| 35 | * Copyright (c) 1990 University of Utah. |
| 36 | * Copyright (c) 1991, 1993 |
| 37 | * The Regents of the University of California. All rights reserved. |
| 38 | * |
| 39 | * This code is derived from software contributed to Berkeley by |
| 40 | * the Systems Programming Group of the University of Utah Computer |
| 41 | * Science Department. |
| 42 | * |
| 43 | * Redistribution and use in source and binary forms, with or without |
| 44 | * modification, are permitted provided that the following conditions |
| 45 | * are met: |
| 46 | * 1. Redistributions of source code must retain the above copyright |
| 47 | * notice, this list of conditions and the following disclaimer. |
| 48 | * 2. Redistributions in binary form must reproduce the above copyright |
| 49 | * notice, this list of conditions and the following disclaimer in the |
| 50 | * documentation and/or other materials provided with the distribution. |
| 51 | * 3. All advertising materials mentioning features or use of this software |
| 52 | * must display the following acknowledgement: |
| 53 | * This product includes software developed by the University of |
| 54 | * California, Berkeley and its contributors. |
| 55 | * 4. Neither the name of the University nor the names of its contributors |
| 56 | * may be used to endorse or promote products derived from this software |
| 57 | * without specific prior written permission. |
| 58 | * |
| 59 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 60 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 61 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 62 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 63 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 64 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 65 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 66 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 67 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 68 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 69 | * SUCH DAMAGE. |
| 70 | * |
| 71 | * New Swap System |
| 72 | * Matthew Dillon |
| 73 | * |
| 74 | * Radix Bitmap 'blists'. |
| 75 | * |
| 76 | * - The new swapper uses the new radix bitmap code. This should scale |
| 77 | * to arbitrarily small or arbitrarily large swap spaces and an almost |
| 78 | * arbitrary degree of fragmentation. |
| 79 | * |
| 80 | * Features: |
| 81 | * |
| 82 | * - on the fly reallocation of swap during putpages. The new system |
| 83 | * does not try to keep previously allocated swap blocks for dirty |
| 84 | * pages. |
| 85 | * |
| 86 | * - on the fly deallocation of swap |
| 87 | * |
| 88 | * - No more garbage collection required. Unnecessarily allocated swap |
| 89 | * blocks only exist for dirty vm_page_t's now and these are already |
| 90 | * cycled (in a high-load system) by the pager. We also do on-the-fly |
| 91 | * removal of invalidated swap blocks when a page is destroyed |
| 92 | * or renamed. |
| 93 | * |
| 94 | * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$ |
| 95 | * |
| 96 | * @(#)swap_pager.c 8.9 (Berkeley) 3/21/94 |
| 97 | * |
| 98 | * $FreeBSD: src/sys/vm/swap_pager.c,v 1.130.2.12 2002/08/31 21:15:55 dillon Exp $ |
| 99 | * $DragonFly: src/sys/vm/swap_pager.c,v 1.32 2008/07/01 02:02:56 dillon Exp $ |
| 100 | */ |
| 101 | |
| 102 | #include <sys/param.h> |
| 103 | #include <sys/systm.h> |
| 104 | #include <sys/conf.h> |
| 105 | #include <sys/kernel.h> |
| 106 | #include <sys/proc.h> |
| 107 | #include <sys/buf.h> |
| 108 | #include <sys/vnode.h> |
| 109 | #include <sys/malloc.h> |
| 110 | #include <sys/vmmeter.h> |
| 111 | #include <sys/sysctl.h> |
| 112 | #include <sys/blist.h> |
| 113 | #include <sys/lock.h> |
| 114 | #include <sys/thread2.h> |
| 115 | |
| 116 | #ifndef MAX_PAGEOUT_CLUSTER |
| 117 | #define MAX_PAGEOUT_CLUSTER 16 |
| 118 | #endif |
| 119 | |
| 120 | #define SWB_NPAGES MAX_PAGEOUT_CLUSTER |
| 121 | |
| 122 | #include "opt_swap.h" |
| 123 | #include <vm/vm.h> |
| 124 | #include <vm/vm_object.h> |
| 125 | #include <vm/vm_page.h> |
| 126 | #include <vm/vm_pager.h> |
| 127 | #include <vm/vm_pageout.h> |
| 128 | #include <vm/swap_pager.h> |
| 129 | #include <vm/vm_extern.h> |
| 130 | #include <vm/vm_zone.h> |
| 131 | #include <vm/vnode_pager.h> |
| 132 | |
| 133 | #include <sys/buf2.h> |
| 134 | #include <vm/vm_page2.h> |
| 135 | |
| 136 | #define SWM_FREE 0x02 /* free, period */ |
| 137 | #define SWM_POP 0x04 /* pop out */ |
| 138 | |
| 139 | #define SWBIO_READ 0x01 |
| 140 | #define SWBIO_WRITE 0x02 |
| 141 | #define SWBIO_SYNC 0x04 |
| 142 | |
| 143 | struct swfreeinfo { |
| 144 | vm_object_t object; |
| 145 | vm_pindex_t basei; |
| 146 | vm_pindex_t begi; |
| 147 | vm_pindex_t endi; /* inclusive */ |
| 148 | }; |
| 149 | |
| 150 | /* |
| 151 | * vm_swap_size is in page-sized chunks now. It was DEV_BSIZE'd chunks |
| 152 | * in the old system. |
| 153 | */ |
| 154 | |
| 155 | int swap_pager_full; /* swap space exhaustion (task killing) */ |
| 156 | int vm_swap_cache_use; |
| 157 | int vm_swap_anon_use; |
| 158 | |
| 159 | static int swap_pager_almost_full; /* swap space exhaustion (w/ hysteresis)*/ |
| 160 | static int nsw_rcount; /* free read buffers */ |
| 161 | static int nsw_wcount_sync; /* limit write buffers / synchronous */ |
| 162 | static int nsw_wcount_async; /* limit write buffers / asynchronous */ |
| 163 | static int nsw_wcount_async_max;/* assigned maximum */ |
| 164 | static int nsw_cluster_max; /* maximum VOP I/O allowed */ |
| 165 | |
| 166 | struct blist *swapblist; |
| 167 | static int swap_async_max = 4; /* maximum in-progress async I/O's */ |
| 168 | static int swap_burst_read = 0; /* allow burst reading */ |
| 169 | |
| 170 | extern struct vnode *swapdev_vp; /* from vm_swap.c */ |
| 171 | |
| 172 | SYSCTL_INT(_vm, OID_AUTO, swap_async_max, |
| 173 | CTLFLAG_RW, &swap_async_max, 0, "Maximum running async swap ops"); |
| 174 | SYSCTL_INT(_vm, OID_AUTO, swap_burst_read, |
| 175 | CTLFLAG_RW, &swap_burst_read, 0, "Allow burst reads for pageins"); |
| 176 | |
| 177 | SYSCTL_INT(_vm, OID_AUTO, swap_cache_use, |
| 178 | CTLFLAG_RD, &vm_swap_cache_use, 0, ""); |
| 179 | SYSCTL_INT(_vm, OID_AUTO, swap_anon_use, |
| 180 | CTLFLAG_RD, &vm_swap_anon_use, 0, ""); |
| 181 | |
| 182 | vm_zone_t swap_zone; |
| 183 | |
| 184 | /* |
| 185 | * Red-Black tree for swblock entries |
| 186 | */ |
| 187 | RB_GENERATE2(swblock_rb_tree, swblock, swb_entry, rb_swblock_compare, |
| 188 | vm_pindex_t, swb_index); |
| 189 | |
| 190 | int |
| 191 | rb_swblock_compare(struct swblock *swb1, struct swblock *swb2) |
| 192 | { |
| 193 | if (swb1->swb_index < swb2->swb_index) |
| 194 | return(-1); |
| 195 | if (swb1->swb_index > swb2->swb_index) |
| 196 | return(1); |
| 197 | return(0); |
| 198 | } |
| 199 | |
| 200 | static |
| 201 | int |
| 202 | rb_swblock_scancmp(struct swblock *swb, void *data) |
| 203 | { |
| 204 | struct swfreeinfo *info = data; |
| 205 | |
| 206 | if (swb->swb_index < info->basei) |
| 207 | return(-1); |
| 208 | if (swb->swb_index > info->endi) |
| 209 | return(1); |
| 210 | return(0); |
| 211 | } |
| 212 | |
| 213 | /* |
| 214 | * pagerops for OBJT_SWAP - "swap pager". Some ops are also global procedure |
| 215 | * calls hooked from other parts of the VM system and do not appear here. |
| 216 | * (see vm/swap_pager.h). |
| 217 | */ |
| 218 | |
| 219 | static vm_object_t |
| 220 | swap_pager_alloc (void *handle, off_t size, |
| 221 | vm_prot_t prot, off_t offset); |
| 222 | static void swap_pager_dealloc (vm_object_t object); |
| 223 | static int swap_pager_getpage (vm_object_t, vm_page_t *, int); |
| 224 | static void swap_chain_iodone(struct bio *biox); |
| 225 | |
| 226 | struct pagerops swappagerops = { |
| 227 | swap_pager_alloc, /* allocate an OBJT_SWAP object */ |
| 228 | swap_pager_dealloc, /* deallocate an OBJT_SWAP object */ |
| 229 | swap_pager_getpage, /* pagein */ |
| 230 | swap_pager_putpages, /* pageout */ |
| 231 | swap_pager_haspage /* get backing store status for page */ |
| 232 | }; |
| 233 | |
| 234 | /* |
| 235 | * dmmax is in page-sized chunks with the new swap system. It was |
| 236 | * dev-bsized chunks in the old. dmmax is always a power of 2. |
| 237 | * |
| 238 | * swap_*() routines are externally accessible. swp_*() routines are |
| 239 | * internal. |
| 240 | */ |
| 241 | |
| 242 | int dmmax; |
| 243 | static int dmmax_mask; |
| 244 | int nswap_lowat = 128; /* in pages, swap_pager_almost_full warn */ |
| 245 | int nswap_hiwat = 512; /* in pages, swap_pager_almost_full warn */ |
| 246 | |
| 247 | static __inline void swp_sizecheck (void); |
| 248 | static void swp_pager_async_iodone (struct bio *bio); |
| 249 | |
| 250 | /* |
| 251 | * Swap bitmap functions |
| 252 | */ |
| 253 | |
| 254 | static __inline void swp_pager_freeswapspace (vm_object_t object, daddr_t blk, int npages); |
| 255 | static __inline daddr_t swp_pager_getswapspace (vm_object_t object, int npages); |
| 256 | |
| 257 | /* |
| 258 | * Metadata functions |
| 259 | */ |
| 260 | |
| 261 | static void swp_pager_meta_convert (vm_object_t); |
| 262 | static void swp_pager_meta_build (vm_object_t, vm_pindex_t, daddr_t); |
| 263 | static void swp_pager_meta_free (vm_object_t, vm_pindex_t, vm_pindex_t); |
| 264 | static void swp_pager_meta_free_all (vm_object_t); |
| 265 | static daddr_t swp_pager_meta_ctl (vm_object_t, vm_pindex_t, int); |
| 266 | |
| 267 | /* |
| 268 | * SWP_SIZECHECK() - update swap_pager_full indication |
| 269 | * |
| 270 | * update the swap_pager_almost_full indication and warn when we are |
| 271 | * about to run out of swap space, using lowat/hiwat hysteresis. |
| 272 | * |
| 273 | * Clear swap_pager_full ( task killing ) indication when lowat is met. |
| 274 | * |
| 275 | * No restrictions on call |
| 276 | * This routine may not block. |
| 277 | * This routine must be called at splvm() |
| 278 | */ |
| 279 | |
| 280 | static __inline void |
| 281 | swp_sizecheck(void) |
| 282 | { |
| 283 | if (vm_swap_size < nswap_lowat) { |
| 284 | if (swap_pager_almost_full == 0) { |
| 285 | kprintf("swap_pager: out of swap space\n"); |
| 286 | swap_pager_almost_full = 1; |
| 287 | } |
| 288 | } else { |
| 289 | swap_pager_full = 0; |
| 290 | if (vm_swap_size > nswap_hiwat) |
| 291 | swap_pager_almost_full = 0; |
| 292 | } |
| 293 | } |
| 294 | |
| 295 | /* |
| 296 | * SWAP_PAGER_INIT() - initialize the swap pager! |
| 297 | * |
| 298 | * Expected to be started from system init. NOTE: This code is run |
| 299 | * before much else so be careful what you depend on. Most of the VM |
| 300 | * system has yet to be initialized at this point. |
| 301 | */ |
| 302 | static void |
| 303 | swap_pager_init(void *arg __unused) |
| 304 | { |
| 305 | /* |
| 306 | * Device Stripe, in PAGE_SIZE'd blocks |
| 307 | */ |
| 308 | dmmax = SWB_NPAGES * 2; |
| 309 | dmmax_mask = ~(dmmax - 1); |
| 310 | } |
| 311 | SYSINIT(vm_mem, SI_BOOT1_VM, SI_ORDER_THIRD, swap_pager_init, NULL) |
| 312 | |
| 313 | /* |
| 314 | * SWAP_PAGER_SWAP_INIT() - swap pager initialization from pageout process |
| 315 | * |
| 316 | * Expected to be started from pageout process once, prior to entering |
| 317 | * its main loop. |
| 318 | */ |
| 319 | |
| 320 | void |
| 321 | swap_pager_swap_init(void) |
| 322 | { |
| 323 | int n, n2; |
| 324 | |
| 325 | /* |
| 326 | * Number of in-transit swap bp operations. Don't |
| 327 | * exhaust the pbufs completely. Make sure we |
| 328 | * initialize workable values (0 will work for hysteresis |
| 329 | * but it isn't very efficient). |
| 330 | * |
| 331 | * The nsw_cluster_max is constrained by the number of pages an XIO |
| 332 | * holds, i.e., (MAXPHYS/PAGE_SIZE) and our locally defined |
| 333 | * MAX_PAGEOUT_CLUSTER. Also be aware that swap ops are |
| 334 | * constrained by the swap device interleave stripe size. |
| 335 | * |
| 336 | * Currently we hardwire nsw_wcount_async to 4. This limit is |
| 337 | * designed to prevent other I/O from having high latencies due to |
| 338 | * our pageout I/O. The value 4 works well for one or two active swap |
| 339 | * devices but is probably a little low if you have more. Even so, |
| 340 | * a higher value would probably generate only a limited improvement |
| 341 | * with three or four active swap devices since the system does not |
| 342 | * typically have to pageout at extreme bandwidths. We will want |
| 343 | * at least 2 per swap devices, and 4 is a pretty good value if you |
| 344 | * have one NFS swap device due to the command/ack latency over NFS. |
| 345 | * So it all works out pretty well. |
| 346 | */ |
| 347 | |
| 348 | nsw_cluster_max = min((MAXPHYS/PAGE_SIZE), MAX_PAGEOUT_CLUSTER); |
| 349 | |
| 350 | nsw_rcount = (nswbuf + 1) / 2; |
| 351 | nsw_wcount_sync = (nswbuf + 3) / 4; |
| 352 | nsw_wcount_async = 4; |
| 353 | nsw_wcount_async_max = nsw_wcount_async; |
| 354 | |
| 355 | /* |
| 356 | * The zone is dynamically allocated so generally size it to |
| 357 | * maxswzone (32MB to 512MB of KVM). Set a minimum size based |
| 358 | * on physical memory of around 8x (each swblock can hold 16 pages). |
| 359 | * |
| 360 | * With the advent of SSDs (vs HDs) the practical (swap:memory) ratio |
| 361 | * has increased dramatically. |
| 362 | */ |
| 363 | n = vmstats.v_page_count / 2; |
| 364 | if (maxswzone && n < maxswzone / sizeof(struct swblock)) |
| 365 | n = maxswzone / sizeof(struct swblock); |
| 366 | n2 = n; |
| 367 | |
| 368 | do { |
| 369 | swap_zone = zinit( |
| 370 | "SWAPMETA", |
| 371 | sizeof(struct swblock), |
| 372 | n, |
| 373 | ZONE_INTERRUPT, |
| 374 | 1); |
| 375 | if (swap_zone != NULL) |
| 376 | break; |
| 377 | /* |
| 378 | * if the allocation failed, try a zone two thirds the |
| 379 | * size of the previous attempt. |
| 380 | */ |
| 381 | n -= ((n + 2) / 3); |
| 382 | } while (n > 0); |
| 383 | |
| 384 | if (swap_zone == NULL) |
| 385 | panic("swap_pager_swap_init: swap_zone == NULL"); |
| 386 | if (n2 != n) |
| 387 | kprintf("Swap zone entries reduced from %d to %d.\n", n2, n); |
| 388 | } |
| 389 | |
| 390 | /* |
| 391 | * SWAP_PAGER_ALLOC() - allocate a new OBJT_SWAP VM object and instantiate |
| 392 | * its metadata structures. |
| 393 | * |
| 394 | * This routine is called from the mmap and fork code to create a new |
| 395 | * OBJT_SWAP object. We do this by creating an OBJT_DEFAULT object |
| 396 | * and then converting it with swp_pager_meta_convert(). |
| 397 | * |
| 398 | * This routine may block in vm_object_allocate() and create a named |
| 399 | * object lookup race, so we must interlock. We must also run at |
| 400 | * splvm() for the object lookup to handle races with interrupts, but |
| 401 | * we do not have to maintain splvm() in between the lookup and the |
| 402 | * add because (I believe) it is not possible to attempt to create |
| 403 | * a new swap object w/handle when a default object with that handle |
| 404 | * already exists. |
| 405 | */ |
| 406 | |
| 407 | static vm_object_t |
| 408 | swap_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t offset) |
| 409 | { |
| 410 | vm_object_t object; |
| 411 | |
| 412 | KKASSERT(handle == NULL); |
| 413 | #if 0 |
| 414 | if (handle) { |
| 415 | /* |
| 416 | * Reference existing named region or allocate new one. There |
| 417 | * should not be a race here against swp_pager_meta_build() |
| 418 | * as called from vm_page_remove() in regards to the lookup |
| 419 | * of the handle. |
| 420 | */ |
| 421 | while (sw_alloc_interlock) { |
| 422 | sw_alloc_interlock = -1; |
| 423 | tsleep(&sw_alloc_interlock, 0, "swpalc", 0); |
| 424 | } |
| 425 | sw_alloc_interlock = 1; |
| 426 | |
| 427 | object = vm_pager_object_lookup(NOBJLIST(handle), handle); |
| 428 | |
| 429 | if (object != NULL) { |
| 430 | vm_object_reference(object); |
| 431 | } else { |
| 432 | object = vm_object_allocate(OBJT_DEFAULT, |
| 433 | OFF_TO_IDX(offset + PAGE_MASK + size)); |
| 434 | object->handle = handle; |
| 435 | swp_pager_meta_convert(object); |
| 436 | } |
| 437 | |
| 438 | if (sw_alloc_interlock < 0) |
| 439 | wakeup(&sw_alloc_interlock); |
| 440 | sw_alloc_interlock = 0; |
| 441 | } else { ... } |
| 442 | #endif |
| 443 | object = vm_object_allocate(OBJT_DEFAULT, |
| 444 | OFF_TO_IDX(offset + PAGE_MASK + size)); |
| 445 | swp_pager_meta_convert(object); |
| 446 | |
| 447 | return (object); |
| 448 | } |
| 449 | |
| 450 | /* |
| 451 | * SWAP_PAGER_DEALLOC() - remove swap metadata from object |
| 452 | * |
| 453 | * The swap backing for the object is destroyed. The code is |
| 454 | * designed such that we can reinstantiate it later, but this |
| 455 | * routine is typically called only when the entire object is |
| 456 | * about to be destroyed. |
| 457 | * |
| 458 | * This routine may block, but no longer does. |
| 459 | * |
| 460 | * The object must be locked or unreferenceable. |
| 461 | */ |
| 462 | |
| 463 | static void |
| 464 | swap_pager_dealloc(vm_object_t object) |
| 465 | { |
| 466 | vm_object_pip_wait(object, "swpdea"); |
| 467 | |
| 468 | /* |
| 469 | * Free all remaining metadata. We only bother to free it from |
| 470 | * the swap meta data. We do not attempt to free swapblk's still |
| 471 | * associated with vm_page_t's for this object. We do not care |
| 472 | * if paging is still in progress on some objects. |
| 473 | */ |
| 474 | crit_enter(); |
| 475 | swp_pager_meta_free_all(object); |
| 476 | crit_exit(); |
| 477 | } |
| 478 | |
| 479 | /************************************************************************ |
| 480 | * SWAP PAGER BITMAP ROUTINES * |
| 481 | ************************************************************************/ |
| 482 | |
| 483 | /* |
| 484 | * SWP_PAGER_GETSWAPSPACE() - allocate raw swap space |
| 485 | * |
| 486 | * Allocate swap for the requested number of pages. The starting |
| 487 | * swap block number (a page index) is returned or SWAPBLK_NONE |
| 488 | * if the allocation failed. |
| 489 | * |
| 490 | * Also has the side effect of advising that somebody made a mistake |
| 491 | * when they configured swap and didn't configure enough. |
| 492 | * |
| 493 | * Must be called at splvm() to avoid races with bitmap frees from |
| 494 | * vm_page_remove() aka swap_pager_page_removed(). |
| 495 | * |
| 496 | * This routine may not block |
| 497 | * This routine must be called at splvm(). |
| 498 | */ |
| 499 | static __inline daddr_t |
| 500 | swp_pager_getswapspace(vm_object_t object, int npages) |
| 501 | { |
| 502 | daddr_t blk; |
| 503 | |
| 504 | if ((blk = blist_alloc(swapblist, npages)) == SWAPBLK_NONE) { |
| 505 | if (swap_pager_full != 2) { |
| 506 | kprintf("swap_pager_getswapspace: failed\n"); |
| 507 | swap_pager_full = 2; |
| 508 | swap_pager_almost_full = 1; |
| 509 | } |
| 510 | } else { |
| 511 | vm_swap_size -= npages; |
| 512 | if (object->type == OBJT_SWAP) |
| 513 | vm_swap_anon_use += npages; |
| 514 | else |
| 515 | vm_swap_cache_use += npages; |
| 516 | swp_sizecheck(); |
| 517 | } |
| 518 | return(blk); |
| 519 | } |
| 520 | |
| 521 | /* |
| 522 | * SWP_PAGER_FREESWAPSPACE() - free raw swap space |
| 523 | * |
| 524 | * This routine returns the specified swap blocks back to the bitmap. |
| 525 | * |
| 526 | * Note: This routine may not block (it could in the old swap code), |
| 527 | * and through the use of the new blist routines it does not block. |
| 528 | * |
| 529 | * We must be called at splvm() to avoid races with bitmap frees from |
| 530 | * vm_page_remove() aka swap_pager_page_removed(). |
| 531 | * |
| 532 | * This routine may not block |
| 533 | * This routine must be called at splvm(). |
| 534 | */ |
| 535 | |
| 536 | static __inline void |
| 537 | swp_pager_freeswapspace(vm_object_t object, daddr_t blk, int npages) |
| 538 | { |
| 539 | blist_free(swapblist, blk, npages); |
| 540 | vm_swap_size += npages; |
| 541 | if (object->type == OBJT_SWAP) |
| 542 | vm_swap_anon_use -= npages; |
| 543 | else |
| 544 | vm_swap_cache_use -= npages; |
| 545 | swp_sizecheck(); |
| 546 | } |
| 547 | |
| 548 | /* |
| 549 | * SWAP_PAGER_FREESPACE() - frees swap blocks associated with a page |
| 550 | * range within an object. |
| 551 | * |
| 552 | * This is a globally accessible routine. |
| 553 | * |
| 554 | * This routine removes swapblk assignments from swap metadata. |
| 555 | * |
| 556 | * The external callers of this routine typically have already destroyed |
| 557 | * or renamed vm_page_t's associated with this range in the object so |
| 558 | * we should be ok. |
| 559 | * |
| 560 | * This routine may be called at any spl. We up our spl to splvm |
| 561 | * temporarily in order to perform the metadata removal. |
| 562 | */ |
| 563 | void |
| 564 | swap_pager_freespace(vm_object_t object, vm_pindex_t start, vm_pindex_t size) |
| 565 | { |
| 566 | crit_enter(); |
| 567 | swp_pager_meta_free(object, start, size); |
| 568 | crit_exit(); |
| 569 | } |
| 570 | |
| 571 | void |
| 572 | swap_pager_freespace_all(vm_object_t object) |
| 573 | { |
| 574 | crit_enter(); |
| 575 | swp_pager_meta_free_all(object); |
| 576 | crit_exit(); |
| 577 | } |
| 578 | |
| 579 | /* |
| 580 | * Called by vm_page_alloc() when a new VM page is inserted |
| 581 | * into a VM object. Checks whether swap has been assigned to |
| 582 | * the page and sets PG_SWAPPED as necessary. |
| 583 | */ |
| 584 | void |
| 585 | swap_pager_page_inserted(vm_page_t m) |
| 586 | { |
| 587 | if (m->object->swblock_count) { |
| 588 | crit_enter(); |
| 589 | if (swp_pager_meta_ctl(m->object, m->pindex, 0) != SWAPBLK_NONE) |
| 590 | vm_page_flag_set(m, PG_SWAPPED); |
| 591 | crit_exit(); |
| 592 | } |
| 593 | } |
| 594 | |
| 595 | /* |
| 596 | * SWAP_PAGER_RESERVE() - reserve swap blocks in object |
| 597 | * |
| 598 | * Assigns swap blocks to the specified range within the object. The |
| 599 | * swap blocks are not zerod. Any previous swap assignment is destroyed. |
| 600 | * |
| 601 | * Returns 0 on success, -1 on failure. |
| 602 | */ |
| 603 | int |
| 604 | swap_pager_reserve(vm_object_t object, vm_pindex_t start, vm_size_t size) |
| 605 | { |
| 606 | int n = 0; |
| 607 | daddr_t blk = SWAPBLK_NONE; |
| 608 | vm_pindex_t beg = start; /* save start index */ |
| 609 | |
| 610 | crit_enter(); |
| 611 | while (size) { |
| 612 | if (n == 0) { |
| 613 | n = BLIST_MAX_ALLOC; |
| 614 | while ((blk = swp_pager_getswapspace(object, n)) == |
| 615 | SWAPBLK_NONE) |
| 616 | { |
| 617 | n >>= 1; |
| 618 | if (n == 0) { |
| 619 | swp_pager_meta_free(object, beg, |
| 620 | start - beg); |
| 621 | crit_exit(); |
| 622 | return(-1); |
| 623 | } |
| 624 | } |
| 625 | } |
| 626 | swp_pager_meta_build(object, start, blk); |
| 627 | --size; |
| 628 | ++start; |
| 629 | ++blk; |
| 630 | --n; |
| 631 | } |
| 632 | swp_pager_meta_free(object, start, n); |
| 633 | crit_exit(); |
| 634 | return(0); |
| 635 | } |
| 636 | |
| 637 | /* |
| 638 | * SWAP_PAGER_COPY() - copy blocks from source pager to destination pager |
| 639 | * and destroy the source. |
| 640 | * |
| 641 | * Copy any valid swapblks from the source to the destination. In |
| 642 | * cases where both the source and destination have a valid swapblk, |
| 643 | * we keep the destination's. |
| 644 | * |
| 645 | * This routine is allowed to block. It may block allocating metadata |
| 646 | * indirectly through swp_pager_meta_build() or if paging is still in |
| 647 | * progress on the source. |
| 648 | * |
| 649 | * This routine can be called at any spl |
| 650 | * |
| 651 | * XXX vm_page_collapse() kinda expects us not to block because we |
| 652 | * supposedly do not need to allocate memory, but for the moment we |
| 653 | * *may* have to get a little memory from the zone allocator, but |
| 654 | * it is taken from the interrupt memory. We should be ok. |
| 655 | * |
| 656 | * The source object contains no vm_page_t's (which is just as well) |
| 657 | * |
| 658 | * The source object is of type OBJT_SWAP. |
| 659 | * |
| 660 | * The source and destination objects must be locked or |
| 661 | * inaccessible (XXX are they ?) |
| 662 | */ |
| 663 | |
| 664 | void |
| 665 | swap_pager_copy(vm_object_t srcobject, vm_object_t dstobject, |
| 666 | vm_pindex_t base_index, int destroysource) |
| 667 | { |
| 668 | vm_pindex_t i; |
| 669 | |
| 670 | crit_enter(); |
| 671 | |
| 672 | /* |
| 673 | * transfer source to destination. |
| 674 | */ |
| 675 | for (i = 0; i < dstobject->size; ++i) { |
| 676 | daddr_t dstaddr; |
| 677 | |
| 678 | /* |
| 679 | * Locate (without changing) the swapblk on the destination, |
| 680 | * unless it is invalid in which case free it silently, or |
| 681 | * if the destination is a resident page, in which case the |
| 682 | * source is thrown away. |
| 683 | */ |
| 684 | dstaddr = swp_pager_meta_ctl(dstobject, i, 0); |
| 685 | |
| 686 | if (dstaddr == SWAPBLK_NONE) { |
| 687 | /* |
| 688 | * Destination has no swapblk and is not resident, |
| 689 | * copy source. |
| 690 | */ |
| 691 | daddr_t srcaddr; |
| 692 | |
| 693 | srcaddr = swp_pager_meta_ctl(srcobject, |
| 694 | base_index + i, SWM_POP); |
| 695 | |
| 696 | if (srcaddr != SWAPBLK_NONE) |
| 697 | swp_pager_meta_build(dstobject, i, srcaddr); |
| 698 | } else { |
| 699 | /* |
| 700 | * Destination has valid swapblk or it is represented |
| 701 | * by a resident page. We destroy the sourceblock. |
| 702 | */ |
| 703 | swp_pager_meta_ctl(srcobject, base_index + i, SWM_FREE); |
| 704 | } |
| 705 | } |
| 706 | |
| 707 | /* |
| 708 | * Free left over swap blocks in source. |
| 709 | * |
| 710 | * We have to revert the type to OBJT_DEFAULT so we do not accidently |
| 711 | * double-remove the object from the swap queues. |
| 712 | */ |
| 713 | if (destroysource) { |
| 714 | /* |
| 715 | * Reverting the type is not necessary, the caller is going |
| 716 | * to destroy srcobject directly, but I'm doing it here |
| 717 | * for consistency since we've removed the object from its |
| 718 | * queues. |
| 719 | */ |
| 720 | swp_pager_meta_free_all(srcobject); |
| 721 | if (srcobject->type == OBJT_SWAP) |
| 722 | srcobject->type = OBJT_DEFAULT; |
| 723 | } |
| 724 | crit_exit(); |
| 725 | } |
| 726 | |
| 727 | /* |
| 728 | * SWAP_PAGER_HASPAGE() - determine if we have good backing store for |
| 729 | * the requested page. |
| 730 | * |
| 731 | * We determine whether good backing store exists for the requested |
| 732 | * page and return TRUE if it does, FALSE if it doesn't. |
| 733 | * |
| 734 | * If TRUE, we also try to determine how much valid, contiguous backing |
| 735 | * store exists before and after the requested page within a reasonable |
| 736 | * distance. We do not try to restrict it to the swap device stripe |
| 737 | * (that is handled in getpages/putpages). It probably isn't worth |
| 738 | * doing here. |
| 739 | */ |
| 740 | |
| 741 | boolean_t |
| 742 | swap_pager_haspage(vm_object_t object, vm_pindex_t pindex) |
| 743 | { |
| 744 | daddr_t blk0; |
| 745 | |
| 746 | /* |
| 747 | * do we have good backing store at the requested index ? |
| 748 | */ |
| 749 | |
| 750 | crit_enter(); |
| 751 | blk0 = swp_pager_meta_ctl(object, pindex, 0); |
| 752 | |
| 753 | if (blk0 == SWAPBLK_NONE) { |
| 754 | crit_exit(); |
| 755 | return (FALSE); |
| 756 | } |
| 757 | |
| 758 | #if 0 |
| 759 | /* |
| 760 | * find backwards-looking contiguous good backing store |
| 761 | */ |
| 762 | if (before != NULL) { |
| 763 | int i; |
| 764 | |
| 765 | for (i = 1; i < (SWB_NPAGES/2); ++i) { |
| 766 | daddr_t blk; |
| 767 | |
| 768 | if (i > pindex) |
| 769 | break; |
| 770 | blk = swp_pager_meta_ctl(object, pindex - i, 0); |
| 771 | if (blk != blk0 - i) |
| 772 | break; |
| 773 | } |
| 774 | *before = (i - 1); |
| 775 | } |
| 776 | |
| 777 | /* |
| 778 | * find forward-looking contiguous good backing store |
| 779 | */ |
| 780 | |
| 781 | if (after != NULL) { |
| 782 | int i; |
| 783 | |
| 784 | for (i = 1; i < (SWB_NPAGES/2); ++i) { |
| 785 | daddr_t blk; |
| 786 | |
| 787 | blk = swp_pager_meta_ctl(object, pindex + i, 0); |
| 788 | if (blk != blk0 + i) |
| 789 | break; |
| 790 | } |
| 791 | *after = (i - 1); |
| 792 | } |
| 793 | #endif |
| 794 | crit_exit(); |
| 795 | return (TRUE); |
| 796 | } |
| 797 | |
| 798 | /* |
| 799 | * SWAP_PAGER_PAGE_UNSWAPPED() - remove swap backing store related to page |
| 800 | * |
| 801 | * This removes any associated swap backing store, whether valid or |
| 802 | * not, from the page. This operates on any VM object, not just OBJT_SWAP |
| 803 | * objects. |
| 804 | * |
| 805 | * This routine is typically called when a page is made dirty, at |
| 806 | * which point any associated swap can be freed. MADV_FREE also |
| 807 | * calls us in a special-case situation |
| 808 | * |
| 809 | * NOTE!!! If the page is clean and the swap was valid, the caller |
| 810 | * should make the page dirty before calling this routine. This routine |
| 811 | * does NOT change the m->dirty status of the page. Also: MADV_FREE |
| 812 | * depends on it. |
| 813 | * |
| 814 | * This routine may not block |
| 815 | * This routine must be called at splvm() |
| 816 | */ |
| 817 | void |
| 818 | swap_pager_unswapped(vm_page_t m) |
| 819 | { |
| 820 | if (m->flags & PG_SWAPPED) { |
| 821 | swp_pager_meta_ctl(m->object, m->pindex, SWM_FREE); |
| 822 | vm_page_flag_clear(m, PG_SWAPPED); |
| 823 | } |
| 824 | } |
| 825 | |
| 826 | /* |
| 827 | * SWAP_PAGER_STRATEGY() - read, write, free blocks |
| 828 | * |
| 829 | * This implements a VM OBJECT strategy function using swap backing store. |
| 830 | * This can operate on any VM OBJECT type, not necessarily just OBJT_SWAP |
| 831 | * types. |
| 832 | * |
| 833 | * This is intended to be a cacheless interface (i.e. caching occurs at |
| 834 | * higher levels), and is also used as a swap-based SSD cache for vnode |
| 835 | * and device objects. |
| 836 | * |
| 837 | * All I/O goes directly to and from the swap device. |
| 838 | * |
| 839 | * We currently attempt to run I/O synchronously or asynchronously as |
| 840 | * the caller requests. This isn't perfect because we loose error |
| 841 | * sequencing when we run multiple ops in parallel to satisfy a request. |
| 842 | * But this is swap, so we let it all hang out. |
| 843 | */ |
| 844 | void |
| 845 | swap_pager_strategy(vm_object_t object, struct bio *bio) |
| 846 | { |
| 847 | struct buf *bp = bio->bio_buf; |
| 848 | struct bio *nbio; |
| 849 | vm_pindex_t start; |
| 850 | vm_pindex_t biox_blkno = 0; |
| 851 | int count; |
| 852 | char *data; |
| 853 | struct bio *biox; |
| 854 | struct buf *bufx; |
| 855 | struct bio_track *track; |
| 856 | |
| 857 | /* |
| 858 | * tracking for swapdev vnode I/Os |
| 859 | */ |
| 860 | if (bp->b_cmd == BUF_CMD_READ) |
| 861 | track = &swapdev_vp->v_track_read; |
| 862 | else |
| 863 | track = &swapdev_vp->v_track_write; |
| 864 | |
| 865 | if (bp->b_bcount & PAGE_MASK) { |
| 866 | bp->b_error = EINVAL; |
| 867 | bp->b_flags |= B_ERROR | B_INVAL; |
| 868 | biodone(bio); |
| 869 | kprintf("swap_pager_strategy: bp %p offset %lld size %d, " |
| 870 | "not page bounded\n", |
| 871 | bp, (long long)bio->bio_offset, (int)bp->b_bcount); |
| 872 | return; |
| 873 | } |
| 874 | |
| 875 | /* |
| 876 | * Clear error indication, initialize page index, count, data pointer. |
| 877 | */ |
| 878 | bp->b_error = 0; |
| 879 | bp->b_flags &= ~B_ERROR; |
| 880 | bp->b_resid = bp->b_bcount; |
| 881 | |
| 882 | start = (vm_pindex_t)(bio->bio_offset >> PAGE_SHIFT); |
| 883 | count = howmany(bp->b_bcount, PAGE_SIZE); |
| 884 | data = bp->b_data; |
| 885 | |
| 886 | /* |
| 887 | * Deal with BUF_CMD_FREEBLKS |
| 888 | */ |
| 889 | if (bp->b_cmd == BUF_CMD_FREEBLKS) { |
| 890 | /* |
| 891 | * FREE PAGE(s) - destroy underlying swap that is no longer |
| 892 | * needed. |
| 893 | */ |
| 894 | swp_pager_meta_free(object, start, count); |
| 895 | bp->b_resid = 0; |
| 896 | biodone(bio); |
| 897 | return; |
| 898 | } |
| 899 | |
| 900 | /* |
| 901 | * We need to be able to create a new cluster of I/O's. We cannot |
| 902 | * use the caller fields of the passed bio so push a new one. |
| 903 | * |
| 904 | * Because nbio is just a placeholder for the cluster links, |
| 905 | * we can biodone() the original bio instead of nbio to make |
| 906 | * things a bit more efficient. |
| 907 | */ |
| 908 | nbio = push_bio(bio); |
| 909 | nbio->bio_offset = bio->bio_offset; |
| 910 | nbio->bio_caller_info1.cluster_head = NULL; |
| 911 | nbio->bio_caller_info2.cluster_tail = NULL; |
| 912 | |
| 913 | biox = NULL; |
| 914 | bufx = NULL; |
| 915 | |
| 916 | /* |
| 917 | * Execute read or write |
| 918 | */ |
| 919 | while (count > 0) { |
| 920 | daddr_t blk; |
| 921 | |
| 922 | /* |
| 923 | * Obtain block. If block not found and writing, allocate a |
| 924 | * new block and build it into the object. |
| 925 | */ |
| 926 | blk = swp_pager_meta_ctl(object, start, 0); |
| 927 | if ((blk == SWAPBLK_NONE) && bp->b_cmd != BUF_CMD_READ) { |
| 928 | blk = swp_pager_getswapspace(object, 1); |
| 929 | if (blk == SWAPBLK_NONE) { |
| 930 | bp->b_error = ENOMEM; |
| 931 | bp->b_flags |= B_ERROR; |
| 932 | break; |
| 933 | } |
| 934 | swp_pager_meta_build(object, start, blk); |
| 935 | } |
| 936 | |
| 937 | /* |
| 938 | * Do we have to flush our current collection? Yes if: |
| 939 | * |
| 940 | * - no swap block at this index |
| 941 | * - swap block is not contiguous |
| 942 | * - we cross a physical disk boundry in the |
| 943 | * stripe. |
| 944 | */ |
| 945 | if ( |
| 946 | biox && (biox_blkno + btoc(bufx->b_bcount) != blk || |
| 947 | ((biox_blkno ^ blk) & dmmax_mask) |
| 948 | ) |
| 949 | ) { |
| 950 | if (bp->b_cmd == BUF_CMD_READ) { |
| 951 | ++mycpu->gd_cnt.v_swapin; |
| 952 | mycpu->gd_cnt.v_swappgsin += btoc(bufx->b_bcount); |
| 953 | } else { |
| 954 | ++mycpu->gd_cnt.v_swapout; |
| 955 | mycpu->gd_cnt.v_swappgsout += btoc(bufx->b_bcount); |
| 956 | bufx->b_dirtyend = bufx->b_bcount; |
| 957 | } |
| 958 | |
| 959 | /* |
| 960 | * Finished with this buf. |
| 961 | */ |
| 962 | KKASSERT(bufx->b_bcount != 0); |
| 963 | if (bufx->b_cmd != BUF_CMD_READ) |
| 964 | bufx->b_dirtyend = bufx->b_bcount; |
| 965 | biox = NULL; |
| 966 | bufx = NULL; |
| 967 | } |
| 968 | |
| 969 | /* |
| 970 | * Add new swapblk to biox, instantiating biox if necessary. |
| 971 | * Zero-fill reads are able to take a shortcut. |
| 972 | */ |
| 973 | if (blk == SWAPBLK_NONE) { |
| 974 | /* |
| 975 | * We can only get here if we are reading. Since |
| 976 | * we are at splvm() we can safely modify b_resid, |
| 977 | * even if chain ops are in progress. |
| 978 | */ |
| 979 | bzero(data, PAGE_SIZE); |
| 980 | bp->b_resid -= PAGE_SIZE; |
| 981 | } else { |
| 982 | if (biox == NULL) { |
| 983 | /* XXX chain count > 4, wait to <= 4 */ |
| 984 | |
| 985 | bufx = getpbuf(NULL); |
| 986 | biox = &bufx->b_bio1; |
| 987 | cluster_append(nbio, bufx); |
| 988 | bufx->b_flags |= (bufx->b_flags & B_ORDERED); |
| 989 | bufx->b_cmd = bp->b_cmd; |
| 990 | biox->bio_done = swap_chain_iodone; |
| 991 | biox->bio_offset = (off_t)blk << PAGE_SHIFT; |
| 992 | biox->bio_caller_info1.cluster_parent = nbio; |
| 993 | biox_blkno = blk; |
| 994 | bufx->b_bcount = 0; |
| 995 | bufx->b_data = data; |
| 996 | } |
| 997 | bufx->b_bcount += PAGE_SIZE; |
| 998 | } |
| 999 | --count; |
| 1000 | ++start; |
| 1001 | data += PAGE_SIZE; |
| 1002 | } |
| 1003 | |
| 1004 | /* |
| 1005 | * Flush out last buffer |
| 1006 | */ |
| 1007 | if (biox) { |
| 1008 | if (bufx->b_cmd == BUF_CMD_READ) { |
| 1009 | ++mycpu->gd_cnt.v_swapin; |
| 1010 | mycpu->gd_cnt.v_swappgsin += btoc(bufx->b_bcount); |
| 1011 | } else { |
| 1012 | ++mycpu->gd_cnt.v_swapout; |
| 1013 | mycpu->gd_cnt.v_swappgsout += btoc(bufx->b_bcount); |
| 1014 | bufx->b_dirtyend = bufx->b_bcount; |
| 1015 | } |
| 1016 | KKASSERT(bufx->b_bcount); |
| 1017 | if (bufx->b_cmd != BUF_CMD_READ) |
| 1018 | bufx->b_dirtyend = bufx->b_bcount; |
| 1019 | /* biox, bufx = NULL */ |
| 1020 | } |
| 1021 | |
| 1022 | /* |
| 1023 | * Now initiate all the I/O. Be careful looping on our chain as |
| 1024 | * I/O's may complete while we are still initiating them. |
| 1025 | */ |
| 1026 | nbio->bio_caller_info2.cluster_tail = NULL; |
| 1027 | bufx = nbio->bio_caller_info1.cluster_head; |
| 1028 | |
| 1029 | while (bufx) { |
| 1030 | biox = &bufx->b_bio1; |
| 1031 | BUF_KERNPROC(bufx); |
| 1032 | bufx = bufx->b_cluster_next; |
| 1033 | vn_strategy(swapdev_vp, biox); |
| 1034 | } |
| 1035 | |
| 1036 | /* |
| 1037 | * Completion of the cluster will also call biodone_chain(nbio). |
| 1038 | * We never call biodone(nbio) so we don't have to worry about |
| 1039 | * setting up a bio_done callback. It's handled in the sub-IO. |
| 1040 | */ |
| 1041 | /**/ |
| 1042 | } |
| 1043 | |
| 1044 | static void |
| 1045 | swap_chain_iodone(struct bio *biox) |
| 1046 | { |
| 1047 | struct buf **nextp; |
| 1048 | struct buf *bufx; /* chained sub-buffer */ |
| 1049 | struct bio *nbio; /* parent nbio with chain glue */ |
| 1050 | struct buf *bp; /* original bp associated with nbio */ |
| 1051 | int chain_empty; |
| 1052 | |
| 1053 | bufx = biox->bio_buf; |
| 1054 | nbio = biox->bio_caller_info1.cluster_parent; |
| 1055 | bp = nbio->bio_buf; |
| 1056 | |
| 1057 | /* |
| 1058 | * Update the original buffer |
| 1059 | */ |
| 1060 | KKASSERT(bp != NULL); |
| 1061 | if (bufx->b_flags & B_ERROR) { |
| 1062 | atomic_set_int(&bufx->b_flags, B_ERROR); |
| 1063 | bp->b_error = bufx->b_error; |
| 1064 | } else if (bufx->b_resid != 0) { |
| 1065 | atomic_set_int(&bufx->b_flags, B_ERROR); |
| 1066 | bp->b_error = EINVAL; |
| 1067 | } else { |
| 1068 | atomic_subtract_int(&bp->b_resid, bufx->b_bcount); |
| 1069 | } |
| 1070 | |
| 1071 | /* |
| 1072 | * Remove us from the chain. |
| 1073 | */ |
| 1074 | spin_lock_wr(&bp->b_lock.lk_spinlock); |
| 1075 | nextp = &nbio->bio_caller_info1.cluster_head; |
| 1076 | while (*nextp != bufx) { |
| 1077 | KKASSERT(*nextp != NULL); |
| 1078 | nextp = &(*nextp)->b_cluster_next; |
| 1079 | } |
| 1080 | *nextp = bufx->b_cluster_next; |
| 1081 | chain_empty = (nbio->bio_caller_info1.cluster_head == NULL); |
| 1082 | spin_unlock_wr(&bp->b_lock.lk_spinlock); |
| 1083 | |
| 1084 | /* |
| 1085 | * Clean up bufx. If the chain is now empty we finish out |
| 1086 | * the parent. Note that we may be racing other completions |
| 1087 | * so we must use the chain_empty status from above. |
| 1088 | */ |
| 1089 | if (chain_empty) { |
| 1090 | if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) { |
| 1091 | atomic_set_int(&bp->b_flags, B_ERROR); |
| 1092 | bp->b_error = EINVAL; |
| 1093 | } |
| 1094 | biodone_chain(nbio); |
| 1095 | } |
| 1096 | relpbuf(bufx, NULL); |
| 1097 | } |
| 1098 | |
| 1099 | /* |
| 1100 | * SWAP_PAGER_GETPAGES() - bring page in from swap |
| 1101 | * |
| 1102 | * The requested page may have to be brought in from swap. Calculate the |
| 1103 | * swap block and bring in additional pages if possible. All pages must |
| 1104 | * have contiguous swap block assignments and reside in the same object. |
| 1105 | * |
| 1106 | * The caller has a single vm_object_pip_add() reference prior to |
| 1107 | * calling us and we should return with the same. |
| 1108 | * |
| 1109 | * The caller has BUSY'd the page. We should return with (*mpp) left busy, |
| 1110 | * and any additinal pages unbusied. |
| 1111 | * |
| 1112 | * If the caller encounters a PG_RAM page it will pass it to us even though |
| 1113 | * it may be valid and dirty. We cannot overwrite the page in this case! |
| 1114 | * The case is used to allow us to issue pure read-aheads. |
| 1115 | * |
| 1116 | * NOTE! XXX This code does not entirely pipeline yet due to the fact that |
| 1117 | * the PG_RAM page is validated at the same time as mreq. What we |
| 1118 | * really need to do is issue a separate read-ahead pbuf. |
| 1119 | */ |
| 1120 | static int |
| 1121 | swap_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess) |
| 1122 | { |
| 1123 | struct buf *bp; |
| 1124 | struct bio *bio; |
| 1125 | vm_page_t mreq; |
| 1126 | vm_page_t m; |
| 1127 | vm_offset_t kva; |
| 1128 | daddr_t blk; |
| 1129 | int i; |
| 1130 | int j; |
| 1131 | int raonly; |
| 1132 | vm_page_t marray[XIO_INTERNAL_PAGES]; |
| 1133 | |
| 1134 | mreq = *mpp; |
| 1135 | |
| 1136 | if (mreq->object != object) { |
| 1137 | panic("swap_pager_getpages: object mismatch %p/%p", |
| 1138 | object, |
| 1139 | mreq->object |
| 1140 | ); |
| 1141 | } |
| 1142 | |
| 1143 | /* |
| 1144 | * We don't want to overwrite a fully valid page as it might be |
| 1145 | * dirty. This case can occur when e.g. vm_fault hits a perfectly |
| 1146 | * valid page with PG_RAM set. |
| 1147 | * |
| 1148 | * In this case we see if the next page is a suitable page-in |
| 1149 | * candidate and if it is we issue read-ahead. PG_RAM will be |
| 1150 | * set on the last page of the read-ahead to continue the pipeline. |
| 1151 | */ |
| 1152 | if (mreq->valid == VM_PAGE_BITS_ALL) { |
| 1153 | if (swap_burst_read == 0 || mreq->pindex + 1 >= object->size) |
| 1154 | return(VM_PAGER_OK); |
| 1155 | crit_enter(); |
| 1156 | blk = swp_pager_meta_ctl(object, mreq->pindex + 1, 0); |
| 1157 | if (blk == SWAPBLK_NONE) { |
| 1158 | crit_exit(); |
| 1159 | return(VM_PAGER_OK); |
| 1160 | } |
| 1161 | m = vm_page_lookup(object, mreq->pindex + 1); |
| 1162 | if (m == NULL) { |
| 1163 | m = vm_page_alloc(object, mreq->pindex + 1, |
| 1164 | VM_ALLOC_QUICK); |
| 1165 | if (m == NULL) { |
| 1166 | crit_exit(); |
| 1167 | return(VM_PAGER_OK); |
| 1168 | } |
| 1169 | } else { |
| 1170 | if ((m->flags & PG_BUSY) || m->busy || m->valid) { |
| 1171 | crit_exit(); |
| 1172 | return(VM_PAGER_OK); |
| 1173 | } |
| 1174 | vm_page_unqueue_nowakeup(m); |
| 1175 | vm_page_busy(m); |
| 1176 | } |
| 1177 | mreq = m; |
| 1178 | raonly = 1; |
| 1179 | crit_exit(); |
| 1180 | } else { |
| 1181 | raonly = 0; |
| 1182 | } |
| 1183 | |
| 1184 | /* |
| 1185 | * Try to block-read contiguous pages from swap if sequential, |
| 1186 | * otherwise just read one page. Contiguous pages from swap must |
| 1187 | * reside within a single device stripe because the I/O cannot be |
| 1188 | * broken up across multiple stripes. |
| 1189 | * |
| 1190 | * Note that blk and iblk can be SWAPBLK_NONE but the loop is |
| 1191 | * set up such that the case(s) are handled implicitly. |
| 1192 | */ |
| 1193 | crit_enter(); |
| 1194 | blk = swp_pager_meta_ctl(mreq->object, mreq->pindex, 0); |
| 1195 | marray[0] = mreq; |
| 1196 | |
| 1197 | for (i = 1; swap_burst_read && |
| 1198 | i < XIO_INTERNAL_PAGES && |
| 1199 | mreq->pindex + i < object->size; ++i) { |
| 1200 | daddr_t iblk; |
| 1201 | |
| 1202 | iblk = swp_pager_meta_ctl(object, mreq->pindex + i, 0); |
| 1203 | if (iblk != blk + i) |
| 1204 | break; |
| 1205 | if ((blk ^ iblk) & dmmax_mask) |
| 1206 | break; |
| 1207 | m = vm_page_lookup(object, mreq->pindex + i); |
| 1208 | if (m == NULL) { |
| 1209 | m = vm_page_alloc(object, mreq->pindex + i, |
| 1210 | VM_ALLOC_QUICK); |
| 1211 | if (m == NULL) |
| 1212 | break; |
| 1213 | } else { |
| 1214 | if ((m->flags & PG_BUSY) || m->busy || m->valid) |
| 1215 | break; |
| 1216 | vm_page_unqueue_nowakeup(m); |
| 1217 | vm_page_busy(m); |
| 1218 | } |
| 1219 | marray[i] = m; |
| 1220 | } |
| 1221 | if (i > 1) |
| 1222 | vm_page_flag_set(marray[i - 1], PG_RAM); |
| 1223 | |
| 1224 | crit_exit(); |
| 1225 | |
| 1226 | /* |
| 1227 | * If mreq is the requested page and we have nothing to do return |
| 1228 | * VM_PAGER_FAIL. If raonly is set mreq is just another read-ahead |
| 1229 | * page and must be cleaned up. |
| 1230 | */ |
| 1231 | if (blk == SWAPBLK_NONE) { |
| 1232 | KKASSERT(i == 1); |
| 1233 | if (raonly) { |
| 1234 | vnode_pager_freepage(mreq); |
| 1235 | return(VM_PAGER_OK); |
| 1236 | } else { |
| 1237 | return(VM_PAGER_FAIL); |
| 1238 | } |
| 1239 | } |
| 1240 | |
| 1241 | /* |
| 1242 | * map our page(s) into kva for input |
| 1243 | */ |
| 1244 | bp = getpbuf(&nsw_rcount); |
| 1245 | bio = &bp->b_bio1; |
| 1246 | kva = (vm_offset_t) bp->b_kvabase; |
| 1247 | bcopy(marray, bp->b_xio.xio_pages, i * sizeof(vm_page_t)); |
| 1248 | pmap_qenter(kva, bp->b_xio.xio_pages, i); |
| 1249 | |
| 1250 | bp->b_data = (caddr_t)kva; |
| 1251 | bp->b_bcount = PAGE_SIZE * i; |
| 1252 | bp->b_xio.xio_npages = i; |
| 1253 | bio->bio_done = swp_pager_async_iodone; |
| 1254 | bio->bio_offset = (off_t)blk << PAGE_SHIFT; |
| 1255 | bio->bio_caller_info1.index = SWBIO_READ; |
| 1256 | |
| 1257 | /* |
| 1258 | * Set index. If raonly set the index beyond the array so all |
| 1259 | * the pages are treated the same, otherwise the original mreq is |
| 1260 | * at index 0. |
| 1261 | */ |
| 1262 | if (raonly) |
| 1263 | bio->bio_driver_info = (void *)(intptr_t)i; |
| 1264 | else |
| 1265 | bio->bio_driver_info = (void *)(intptr_t)0; |
| 1266 | |
| 1267 | for (j = 0; j < i; ++j) |
| 1268 | vm_page_flag_set(bp->b_xio.xio_pages[j], PG_SWAPINPROG); |
| 1269 | |
| 1270 | mycpu->gd_cnt.v_swapin++; |
| 1271 | mycpu->gd_cnt.v_swappgsin += bp->b_xio.xio_npages; |
| 1272 | |
| 1273 | /* |
| 1274 | * We still hold the lock on mreq, and our automatic completion routine |
| 1275 | * does not remove it. |
| 1276 | */ |
| 1277 | vm_object_pip_add(object, bp->b_xio.xio_npages); |
| 1278 | |
| 1279 | /* |
| 1280 | * perform the I/O. NOTE!!! bp cannot be considered valid after |
| 1281 | * this point because we automatically release it on completion. |
| 1282 | * Instead, we look at the one page we are interested in which we |
| 1283 | * still hold a lock on even through the I/O completion. |
| 1284 | * |
| 1285 | * The other pages in our m[] array are also released on completion, |
| 1286 | * so we cannot assume they are valid anymore either. |
| 1287 | */ |
| 1288 | bp->b_cmd = BUF_CMD_READ; |
| 1289 | BUF_KERNPROC(bp); |
| 1290 | vn_strategy(swapdev_vp, bio); |
| 1291 | |
| 1292 | /* |
| 1293 | * Wait for the page we want to complete. PG_SWAPINPROG is always |
| 1294 | * cleared on completion. If an I/O error occurs, SWAPBLK_NONE |
| 1295 | * is set in the meta-data. |
| 1296 | * |
| 1297 | * If this is a read-ahead only we return immediately without |
| 1298 | * waiting for I/O. |
| 1299 | */ |
| 1300 | if (raonly) |
| 1301 | return(VM_PAGER_OK); |
| 1302 | |
| 1303 | /* |
| 1304 | * Read-ahead includes originally requested page case. |
| 1305 | */ |
| 1306 | crit_enter(); |
| 1307 | while ((mreq->flags & PG_SWAPINPROG) != 0) { |
| 1308 | vm_page_flag_set(mreq, PG_WANTED | PG_REFERENCED); |
| 1309 | mycpu->gd_cnt.v_intrans++; |
| 1310 | if (tsleep(mreq, 0, "swread", hz*20)) { |
| 1311 | kprintf( |
| 1312 | "swap_pager: indefinite wait buffer: " |
| 1313 | " offset: %lld, size: %ld\n", |
| 1314 | (long long)bio->bio_offset, |
| 1315 | (long)bp->b_bcount |
| 1316 | ); |
| 1317 | } |
| 1318 | } |
| 1319 | crit_exit(); |
| 1320 | |
| 1321 | /* |
| 1322 | * mreq is left bussied after completion, but all the other pages |
| 1323 | * are freed. If we had an unrecoverable read error the page will |
| 1324 | * not be valid. |
| 1325 | */ |
| 1326 | if (mreq->valid != VM_PAGE_BITS_ALL) |
| 1327 | return(VM_PAGER_ERROR); |
| 1328 | else |
| 1329 | return(VM_PAGER_OK); |
| 1330 | |
| 1331 | /* |
| 1332 | * A final note: in a low swap situation, we cannot deallocate swap |
| 1333 | * and mark a page dirty here because the caller is likely to mark |
| 1334 | * the page clean when we return, causing the page to possibly revert |
| 1335 | * to all-zero's later. |
| 1336 | */ |
| 1337 | } |
| 1338 | |
| 1339 | /* |
| 1340 | * swap_pager_putpages: |
| 1341 | * |
| 1342 | * Assign swap (if necessary) and initiate I/O on the specified pages. |
| 1343 | * |
| 1344 | * We support both OBJT_DEFAULT and OBJT_SWAP objects. DEFAULT objects |
| 1345 | * are automatically converted to SWAP objects. |
| 1346 | * |
| 1347 | * In a low memory situation we may block in vn_strategy(), but the new |
| 1348 | * vm_page reservation system coupled with properly written VFS devices |
| 1349 | * should ensure that no low-memory deadlock occurs. This is an area |
| 1350 | * which needs work. |
| 1351 | * |
| 1352 | * The parent has N vm_object_pip_add() references prior to |
| 1353 | * calling us and will remove references for rtvals[] that are |
| 1354 | * not set to VM_PAGER_PEND. We need to remove the rest on I/O |
| 1355 | * completion. |
| 1356 | * |
| 1357 | * The parent has soft-busy'd the pages it passes us and will unbusy |
| 1358 | * those whos rtvals[] entry is not set to VM_PAGER_PEND on return. |
| 1359 | * We need to unbusy the rest on I/O completion. |
| 1360 | */ |
| 1361 | void |
| 1362 | swap_pager_putpages(vm_object_t object, vm_page_t *m, int count, |
| 1363 | boolean_t sync, int *rtvals) |
| 1364 | { |
| 1365 | int i; |
| 1366 | int n = 0; |
| 1367 | |
| 1368 | if (count && m[0]->object != object) { |
| 1369 | panic("swap_pager_getpages: object mismatch %p/%p", |
| 1370 | object, |
| 1371 | m[0]->object |
| 1372 | ); |
| 1373 | } |
| 1374 | |
| 1375 | /* |
| 1376 | * Step 1 |
| 1377 | * |
| 1378 | * Turn object into OBJT_SWAP |
| 1379 | * check for bogus sysops |
| 1380 | * force sync if not pageout process |
| 1381 | */ |
| 1382 | if (object->type == OBJT_DEFAULT) |
| 1383 | swp_pager_meta_convert(object); |
| 1384 | |
| 1385 | if (curthread != pagethread) |
| 1386 | sync = TRUE; |
| 1387 | |
| 1388 | /* |
| 1389 | * Step 2 |
| 1390 | * |
| 1391 | * Update nsw parameters from swap_async_max sysctl values. |
| 1392 | * Do not let the sysop crash the machine with bogus numbers. |
| 1393 | */ |
| 1394 | |
| 1395 | if (swap_async_max != nsw_wcount_async_max) { |
| 1396 | int n; |
| 1397 | |
| 1398 | /* |
| 1399 | * limit range |
| 1400 | */ |
| 1401 | if ((n = swap_async_max) > nswbuf / 2) |
| 1402 | n = nswbuf / 2; |
| 1403 | if (n < 1) |
| 1404 | n = 1; |
| 1405 | swap_async_max = n; |
| 1406 | |
| 1407 | /* |
| 1408 | * Adjust difference ( if possible ). If the current async |
| 1409 | * count is too low, we may not be able to make the adjustment |
| 1410 | * at this time. |
| 1411 | */ |
| 1412 | crit_enter(); |
| 1413 | n -= nsw_wcount_async_max; |
| 1414 | if (nsw_wcount_async + n >= 0) { |
| 1415 | nsw_wcount_async += n; |
| 1416 | nsw_wcount_async_max += n; |
| 1417 | wakeup(&nsw_wcount_async); |
| 1418 | } |
| 1419 | crit_exit(); |
| 1420 | } |
| 1421 | |
| 1422 | /* |
| 1423 | * Step 3 |
| 1424 | * |
| 1425 | * Assign swap blocks and issue I/O. We reallocate swap on the fly. |
| 1426 | * The page is left dirty until the pageout operation completes |
| 1427 | * successfully. |
| 1428 | */ |
| 1429 | |
| 1430 | for (i = 0; i < count; i += n) { |
| 1431 | struct buf *bp; |
| 1432 | struct bio *bio; |
| 1433 | daddr_t blk; |
| 1434 | int j; |
| 1435 | |
| 1436 | /* |
| 1437 | * Maximum I/O size is limited by a number of factors. |
| 1438 | */ |
| 1439 | |
| 1440 | n = min(BLIST_MAX_ALLOC, count - i); |
| 1441 | n = min(n, nsw_cluster_max); |
| 1442 | |
| 1443 | crit_enter(); |
| 1444 | |
| 1445 | /* |
| 1446 | * Get biggest block of swap we can. If we fail, fall |
| 1447 | * back and try to allocate a smaller block. Don't go |
| 1448 | * overboard trying to allocate space if it would overly |
| 1449 | * fragment swap. |
| 1450 | */ |
| 1451 | while ( |
| 1452 | (blk = swp_pager_getswapspace(object, n)) == SWAPBLK_NONE && |
| 1453 | n > 4 |
| 1454 | ) { |
| 1455 | n >>= 1; |
| 1456 | } |
| 1457 | if (blk == SWAPBLK_NONE) { |
| 1458 | for (j = 0; j < n; ++j) |
| 1459 | rtvals[i+j] = VM_PAGER_FAIL; |
| 1460 | crit_exit(); |
| 1461 | continue; |
| 1462 | } |
| 1463 | |
| 1464 | /* |
| 1465 | * The I/O we are constructing cannot cross a physical |
| 1466 | * disk boundry in the swap stripe. Note: we are still |
| 1467 | * at splvm(). |
| 1468 | */ |
| 1469 | if ((blk ^ (blk + n)) & dmmax_mask) { |
| 1470 | j = ((blk + dmmax) & dmmax_mask) - blk; |
| 1471 | swp_pager_freeswapspace(object, blk + j, n - j); |
| 1472 | n = j; |
| 1473 | } |
| 1474 | |
| 1475 | /* |
| 1476 | * All I/O parameters have been satisfied, build the I/O |
| 1477 | * request and assign the swap space. |
| 1478 | */ |
| 1479 | if (sync == TRUE) |
| 1480 | bp = getpbuf(&nsw_wcount_sync); |
| 1481 | else |
| 1482 | bp = getpbuf(&nsw_wcount_async); |
| 1483 | bio = &bp->b_bio1; |
| 1484 | |
| 1485 | pmap_qenter((vm_offset_t)bp->b_data, &m[i], n); |
| 1486 | |
| 1487 | bp->b_bcount = PAGE_SIZE * n; |
| 1488 | bio->bio_offset = (off_t)blk << PAGE_SHIFT; |
| 1489 | |
| 1490 | for (j = 0; j < n; ++j) { |
| 1491 | vm_page_t mreq = m[i+j]; |
| 1492 | |
| 1493 | swp_pager_meta_build(mreq->object, mreq->pindex, |
| 1494 | blk + j); |
| 1495 | if (object->type == OBJT_SWAP) |
| 1496 | vm_page_dirty(mreq); |
| 1497 | rtvals[i+j] = VM_PAGER_OK; |
| 1498 | |
| 1499 | vm_page_flag_set(mreq, PG_SWAPINPROG); |
| 1500 | bp->b_xio.xio_pages[j] = mreq; |
| 1501 | } |
| 1502 | bp->b_xio.xio_npages = n; |
| 1503 | |
| 1504 | mycpu->gd_cnt.v_swapout++; |
| 1505 | mycpu->gd_cnt.v_swappgsout += bp->b_xio.xio_npages; |
| 1506 | |
| 1507 | crit_exit(); |
| 1508 | |
| 1509 | bp->b_dirtyoff = 0; /* req'd for NFS */ |
| 1510 | bp->b_dirtyend = bp->b_bcount; /* req'd for NFS */ |
| 1511 | bp->b_cmd = BUF_CMD_WRITE; |
| 1512 | bio->bio_caller_info1.index = SWBIO_WRITE; |
| 1513 | |
| 1514 | /* |
| 1515 | * asynchronous |
| 1516 | */ |
| 1517 | if (sync == FALSE) { |
| 1518 | bio->bio_done = swp_pager_async_iodone; |
| 1519 | BUF_KERNPROC(bp); |
| 1520 | vn_strategy(swapdev_vp, bio); |
| 1521 | |
| 1522 | for (j = 0; j < n; ++j) |
| 1523 | rtvals[i+j] = VM_PAGER_PEND; |
| 1524 | continue; |
| 1525 | } |
| 1526 | |
| 1527 | /* |
| 1528 | * Issue synchrnously. |
| 1529 | * |
| 1530 | * Wait for the sync I/O to complete, then update rtvals. |
| 1531 | * We just set the rtvals[] to VM_PAGER_PEND so we can call |
| 1532 | * our async completion routine at the end, thus avoiding a |
| 1533 | * double-free. |
| 1534 | */ |
| 1535 | bio->bio_caller_info1.index |= SWBIO_SYNC; |
| 1536 | bio->bio_done = biodone_sync; |
| 1537 | bio->bio_flags |= BIO_SYNC; |
| 1538 | vn_strategy(swapdev_vp, bio); |
| 1539 | biowait(bio, "swwrt"); |
| 1540 | |
| 1541 | for (j = 0; j < n; ++j) |
| 1542 | rtvals[i+j] = VM_PAGER_PEND; |
| 1543 | |
| 1544 | /* |
| 1545 | * Now that we are through with the bp, we can call the |
| 1546 | * normal async completion, which frees everything up. |
| 1547 | */ |
| 1548 | swp_pager_async_iodone(bio); |
| 1549 | } |
| 1550 | } |
| 1551 | |
| 1552 | void |
| 1553 | swap_pager_newswap(void) |
| 1554 | { |
| 1555 | swp_sizecheck(); |
| 1556 | } |
| 1557 | |
| 1558 | /* |
| 1559 | * swp_pager_async_iodone: |
| 1560 | * |
| 1561 | * Completion routine for asynchronous reads and writes from/to swap. |
| 1562 | * Also called manually by synchronous code to finish up a bp. |
| 1563 | * |
| 1564 | * For READ operations, the pages are PG_BUSY'd. For WRITE operations, |
| 1565 | * the pages are vm_page_t->busy'd. For READ operations, we PG_BUSY |
| 1566 | * unbusy all pages except the 'main' request page. For WRITE |
| 1567 | * operations, we vm_page_t->busy'd unbusy all pages ( we can do this |
| 1568 | * because we marked them all VM_PAGER_PEND on return from putpages ). |
| 1569 | * |
| 1570 | * This routine may not block. |
| 1571 | */ |
| 1572 | static void |
| 1573 | swp_pager_async_iodone(struct bio *bio) |
| 1574 | { |
| 1575 | struct buf *bp = bio->bio_buf; |
| 1576 | vm_object_t object = NULL; |
| 1577 | int i; |
| 1578 | int *nswptr; |
| 1579 | |
| 1580 | /* |
| 1581 | * report error |
| 1582 | */ |
| 1583 | if (bp->b_flags & B_ERROR) { |
| 1584 | kprintf( |
| 1585 | "swap_pager: I/O error - %s failed; offset %lld," |
| 1586 | "size %ld, error %d\n", |
| 1587 | ((bio->bio_caller_info1.index & SWBIO_READ) ? |
| 1588 | "pagein" : "pageout"), |
| 1589 | (long long)bio->bio_offset, |
| 1590 | (long)bp->b_bcount, |
| 1591 | bp->b_error |
| 1592 | ); |
| 1593 | } |
| 1594 | |
| 1595 | /* |
| 1596 | * set object, raise to splvm(). |
| 1597 | */ |
| 1598 | if (bp->b_xio.xio_npages) |
| 1599 | object = bp->b_xio.xio_pages[0]->object; |
| 1600 | crit_enter(); |
| 1601 | |
| 1602 | /* |
| 1603 | * remove the mapping for kernel virtual |
| 1604 | */ |
| 1605 | pmap_qremove((vm_offset_t)bp->b_data, bp->b_xio.xio_npages); |
| 1606 | |
| 1607 | /* |
| 1608 | * cleanup pages. If an error occurs writing to swap, we are in |
| 1609 | * very serious trouble. If it happens to be a disk error, though, |
| 1610 | * we may be able to recover by reassigning the swap later on. So |
| 1611 | * in this case we remove the m->swapblk assignment for the page |
| 1612 | * but do not free it in the rlist. The errornous block(s) are thus |
| 1613 | * never reallocated as swap. Redirty the page and continue. |
| 1614 | */ |
| 1615 | for (i = 0; i < bp->b_xio.xio_npages; ++i) { |
| 1616 | vm_page_t m = bp->b_xio.xio_pages[i]; |
| 1617 | |
| 1618 | if (bp->b_flags & B_ERROR) { |
| 1619 | /* |
| 1620 | * If an error occurs I'd love to throw the swapblk |
| 1621 | * away without freeing it back to swapspace, so it |
| 1622 | * can never be used again. But I can't from an |
| 1623 | * interrupt. |
| 1624 | */ |
| 1625 | |
| 1626 | if (bio->bio_caller_info1.index & SWBIO_READ) { |
| 1627 | /* |
| 1628 | * When reading, reqpage needs to stay |
| 1629 | * locked for the parent, but all other |
| 1630 | * pages can be freed. We still want to |
| 1631 | * wakeup the parent waiting on the page, |
| 1632 | * though. ( also: pg_reqpage can be -1 and |
| 1633 | * not match anything ). |
| 1634 | * |
| 1635 | * We have to wake specifically requested pages |
| 1636 | * up too because we cleared PG_SWAPINPROG and |
| 1637 | * someone may be waiting for that. |
| 1638 | * |
| 1639 | * NOTE: for reads, m->dirty will probably |
| 1640 | * be overridden by the original caller of |
| 1641 | * getpages so don't play cute tricks here. |
| 1642 | * |
| 1643 | * NOTE: We can't actually free the page from |
| 1644 | * here, because this is an interrupt. It |
| 1645 | * is not legal to mess with object->memq |
| 1646 | * from an interrupt. Deactivate the page |
| 1647 | * instead. |
| 1648 | */ |
| 1649 | |
| 1650 | m->valid = 0; |
| 1651 | vm_page_flag_clear(m, PG_ZERO); |
| 1652 | vm_page_flag_clear(m, PG_SWAPINPROG); |
| 1653 | |
| 1654 | /* |
| 1655 | * bio_driver_info holds the requested page |
| 1656 | * index. |
| 1657 | */ |
| 1658 | if (i != (int)(intptr_t)bio->bio_driver_info) { |
| 1659 | vm_page_deactivate(m); |
| 1660 | vm_page_wakeup(m); |
| 1661 | } else { |
| 1662 | vm_page_flash(m); |
| 1663 | } |
| 1664 | /* |
| 1665 | * If i == bp->b_pager.pg_reqpage, do not wake |
| 1666 | * the page up. The caller needs to. |
| 1667 | */ |
| 1668 | } else { |
| 1669 | /* |
| 1670 | * If a write error occurs, reactivate page |
| 1671 | * so it doesn't clog the inactive list, |
| 1672 | * then finish the I/O. |
| 1673 | * |
| 1674 | * Only for OBJT_SWAP. When using the swap |
| 1675 | * as a cache for clean vnode-backed pages |
| 1676 | * we don't mess with the page dirty state. |
| 1677 | */ |
| 1678 | vm_page_flag_clear(m, PG_SWAPINPROG); |
| 1679 | if (m->object->type == OBJT_SWAP) { |
| 1680 | vm_page_dirty(m); |
| 1681 | vm_page_activate(m); |
| 1682 | } |
| 1683 | vm_page_io_finish(m); |
| 1684 | } |
| 1685 | } else if (bio->bio_caller_info1.index & SWBIO_READ) { |
| 1686 | /* |
| 1687 | * NOTE: for reads, m->dirty will probably be |
| 1688 | * overridden by the original caller of getpages so |
| 1689 | * we cannot set them in order to free the underlying |
| 1690 | * swap in a low-swap situation. I don't think we'd |
| 1691 | * want to do that anyway, but it was an optimization |
| 1692 | * that existed in the old swapper for a time before |
| 1693 | * it got ripped out due to precisely this problem. |
| 1694 | * |
| 1695 | * clear PG_ZERO in page. |
| 1696 | * |
| 1697 | * If not the requested page then deactivate it. |
| 1698 | * |
| 1699 | * Note that the requested page, reqpage, is left |
| 1700 | * busied, but we still have to wake it up. The |
| 1701 | * other pages are released (unbusied) by |
| 1702 | * vm_page_wakeup(). We do not set reqpage's |
| 1703 | * valid bits here, it is up to the caller. |
| 1704 | */ |
| 1705 | |
| 1706 | /* |
| 1707 | * NOTE: can't call pmap_clear_modify(m) from an |
| 1708 | * interrupt thread, the pmap code may have to map |
| 1709 | * non-kernel pmaps and currently asserts the case. |
| 1710 | */ |
| 1711 | /*pmap_clear_modify(m);*/ |
| 1712 | m->valid = VM_PAGE_BITS_ALL; |
| 1713 | vm_page_undirty(m); |
| 1714 | vm_page_flag_clear(m, PG_ZERO | PG_SWAPINPROG); |
| 1715 | vm_page_flag_set(m, PG_SWAPPED); |
| 1716 | |
| 1717 | /* |
| 1718 | * We have to wake specifically requested pages |
| 1719 | * up too because we cleared PG_SWAPINPROG and |
| 1720 | * could be waiting for it in getpages. However, |
| 1721 | * be sure to not unbusy getpages specifically |
| 1722 | * requested page - getpages expects it to be |
| 1723 | * left busy. |
| 1724 | * |
| 1725 | * bio_driver_info holds the requested page |
| 1726 | */ |
| 1727 | if (i != (int)(intptr_t)bio->bio_driver_info) { |
| 1728 | vm_page_deactivate(m); |
| 1729 | vm_page_wakeup(m); |
| 1730 | } else { |
| 1731 | vm_page_flash(m); |
| 1732 | } |
| 1733 | } else { |
| 1734 | /* |
| 1735 | * Mark the page clean but do not mess with the |
| 1736 | * pmap-layer's modified state. That state should |
| 1737 | * also be clear since the caller protected the |
| 1738 | * page VM_PROT_READ, but allow the case. |
| 1739 | * |
| 1740 | * We are in an interrupt, avoid pmap operations. |
| 1741 | * |
| 1742 | * If we have a severe page deficit, deactivate the |
| 1743 | * page. Do not try to cache it (which would also |
| 1744 | * involve a pmap op), because the page might still |
| 1745 | * be read-heavy. |
| 1746 | * |
| 1747 | * When using the swap to cache clean vnode pages |
| 1748 | * we do not mess with the page dirty bits. |
| 1749 | */ |
| 1750 | if (m->object->type == OBJT_SWAP) |
| 1751 | vm_page_undirty(m); |
| 1752 | vm_page_flag_clear(m, PG_SWAPINPROG); |
| 1753 | vm_page_flag_set(m, PG_SWAPPED); |
| 1754 | vm_page_io_finish(m); |
| 1755 | if (vm_page_count_severe()) |
| 1756 | vm_page_deactivate(m); |
| 1757 | #if 0 |
| 1758 | if (!vm_page_count_severe() || !vm_page_try_to_cache(m)) |
| 1759 | vm_page_protect(m, VM_PROT_READ); |
| 1760 | #endif |
| 1761 | } |
| 1762 | } |
| 1763 | |
| 1764 | /* |
| 1765 | * adjust pip. NOTE: the original parent may still have its own |
| 1766 | * pip refs on the object. |
| 1767 | */ |
| 1768 | |
| 1769 | if (object) |
| 1770 | vm_object_pip_wakeupn(object, bp->b_xio.xio_npages); |
| 1771 | |
| 1772 | /* |
| 1773 | * Release the physical I/O buffer. |
| 1774 | * |
| 1775 | * NOTE: Due to synchronous operations in the write case b_cmd may |
| 1776 | * already be set to BUF_CMD_DONE and BIO_SYNC may have already |
| 1777 | * been cleared. |
| 1778 | */ |
| 1779 | if (bio->bio_caller_info1.index & SWBIO_READ) |
| 1780 | nswptr = &nsw_rcount; |
| 1781 | else if (bio->bio_caller_info1.index & SWBIO_SYNC) |
| 1782 | nswptr = &nsw_wcount_sync; |
| 1783 | else |
| 1784 | nswptr = &nsw_wcount_async; |
| 1785 | bp->b_cmd = BUF_CMD_DONE; |
| 1786 | relpbuf(bp, nswptr); |
| 1787 | crit_exit(); |
| 1788 | } |
| 1789 | |
| 1790 | /************************************************************************ |
| 1791 | * SWAP META DATA * |
| 1792 | ************************************************************************ |
| 1793 | * |
| 1794 | * These routines manipulate the swap metadata stored in the |
| 1795 | * OBJT_SWAP object. All swp_*() routines must be called at |
| 1796 | * splvm() because swap can be freed up by the low level vm_page |
| 1797 | * code which might be called from interrupts beyond what splbio() covers. |
| 1798 | * |
| 1799 | * Swap metadata is implemented with a global hash and not directly |
| 1800 | * linked into the object. Instead the object simply contains |
| 1801 | * appropriate tracking counters. |
| 1802 | */ |
| 1803 | |
| 1804 | /* |
| 1805 | * Lookup the swblock containing the specified swap block index. |
| 1806 | */ |
| 1807 | static __inline |
| 1808 | struct swblock * |
| 1809 | swp_pager_lookup(vm_object_t object, vm_pindex_t index) |
| 1810 | { |
| 1811 | index &= ~SWAP_META_MASK; |
| 1812 | return (RB_LOOKUP(swblock_rb_tree, &object->swblock_root, index)); |
| 1813 | } |
| 1814 | |
| 1815 | /* |
| 1816 | * Remove a swblock from the RB tree. |
| 1817 | */ |
| 1818 | static __inline |
| 1819 | void |
| 1820 | swp_pager_remove(vm_object_t object, struct swblock *swap) |
| 1821 | { |
| 1822 | RB_REMOVE(swblock_rb_tree, &object->swblock_root, swap); |
| 1823 | } |
| 1824 | |
| 1825 | /* |
| 1826 | * Convert default object to swap object if necessary |
| 1827 | */ |
| 1828 | static void |
| 1829 | swp_pager_meta_convert(vm_object_t object) |
| 1830 | { |
| 1831 | if (object->type == OBJT_DEFAULT) { |
| 1832 | object->type = OBJT_SWAP; |
| 1833 | KKASSERT(object->swblock_count == 0); |
| 1834 | } |
| 1835 | } |
| 1836 | |
| 1837 | /* |
| 1838 | * SWP_PAGER_META_BUILD() - add swap block to swap meta data for object |
| 1839 | * |
| 1840 | * We first convert the object to a swap object if it is a default |
| 1841 | * object. Vnode objects do not need to be converted. |
| 1842 | * |
| 1843 | * The specified swapblk is added to the object's swap metadata. If |
| 1844 | * the swapblk is not valid, it is freed instead. Any previously |
| 1845 | * assigned swapblk is freed. |
| 1846 | */ |
| 1847 | static void |
| 1848 | swp_pager_meta_build(vm_object_t object, vm_pindex_t index, daddr_t swapblk) |
| 1849 | { |
| 1850 | struct swblock *swap; |
| 1851 | struct swblock *oswap; |
| 1852 | |
| 1853 | KKASSERT(swapblk != SWAPBLK_NONE); |
| 1854 | |
| 1855 | /* |
| 1856 | * Convert object if necessary |
| 1857 | */ |
| 1858 | if (object->type == OBJT_DEFAULT) |
| 1859 | swp_pager_meta_convert(object); |
| 1860 | |
| 1861 | /* |
| 1862 | * Locate swblock. If not found create, but if we aren't adding |
| 1863 | * anything just return. If we run out of space in the map we wait |
| 1864 | * and, since the hash table may have changed, retry. |
| 1865 | */ |
| 1866 | retry: |
| 1867 | swap = swp_pager_lookup(object, index); |
| 1868 | |
| 1869 | if (swap == NULL) { |
| 1870 | int i; |
| 1871 | |
| 1872 | swap = zalloc(swap_zone); |
| 1873 | if (swap == NULL) { |
| 1874 | vm_wait(0); |
| 1875 | goto retry; |
| 1876 | } |
| 1877 | swap->swb_index = index & ~SWAP_META_MASK; |
| 1878 | swap->swb_count = 0; |
| 1879 | |
| 1880 | ++object->swblock_count; |
| 1881 | |
| 1882 | for (i = 0; i < SWAP_META_PAGES; ++i) |
| 1883 | swap->swb_pages[i] = SWAPBLK_NONE; |
| 1884 | oswap = RB_INSERT(swblock_rb_tree, &object->swblock_root, swap); |
| 1885 | KKASSERT(oswap == NULL); |
| 1886 | } |
| 1887 | |
| 1888 | /* |
| 1889 | * Delete prior contents of metadata |
| 1890 | */ |
| 1891 | |
| 1892 | index &= SWAP_META_MASK; |
| 1893 | |
| 1894 | if (swap->swb_pages[index] != SWAPBLK_NONE) { |
| 1895 | swp_pager_freeswapspace(object, swap->swb_pages[index], 1); |
| 1896 | --swap->swb_count; |
| 1897 | } |
| 1898 | |
| 1899 | /* |
| 1900 | * Enter block into metadata |
| 1901 | */ |
| 1902 | swap->swb_pages[index] = swapblk; |
| 1903 | if (swapblk != SWAPBLK_NONE) |
| 1904 | ++swap->swb_count; |
| 1905 | } |
| 1906 | |
| 1907 | /* |
| 1908 | * SWP_PAGER_META_FREE() - free a range of blocks in the object's swap metadata |
| 1909 | * |
| 1910 | * The requested range of blocks is freed, with any associated swap |
| 1911 | * returned to the swap bitmap. |
| 1912 | * |
| 1913 | * This routine will free swap metadata structures as they are cleaned |
| 1914 | * out. This routine does *NOT* operate on swap metadata associated |
| 1915 | * with resident pages. |
| 1916 | * |
| 1917 | * This routine must be called at splvm() |
| 1918 | */ |
| 1919 | static int swp_pager_meta_free_callback(struct swblock *swb, void *data); |
| 1920 | |
| 1921 | static void |
| 1922 | swp_pager_meta_free(vm_object_t object, vm_pindex_t index, vm_pindex_t count) |
| 1923 | { |
| 1924 | struct swfreeinfo info; |
| 1925 | |
| 1926 | /* |
| 1927 | * Nothing to do |
| 1928 | */ |
| 1929 | if (object->swblock_count == 0) { |
| 1930 | KKASSERT(RB_EMPTY(&object->swblock_root)); |
| 1931 | return; |
| 1932 | } |
| 1933 | if (count == 0) |
| 1934 | return; |
| 1935 | |
| 1936 | /* |
| 1937 | * Setup for RB tree scan. Note that the pindex range can be huge |
| 1938 | * due to the 64 bit page index space so we cannot safely iterate. |
| 1939 | */ |
| 1940 | info.object = object; |
| 1941 | info.basei = index & ~SWAP_META_MASK; |
| 1942 | info.begi = index; |
| 1943 | info.endi = index + count - 1; |
| 1944 | swblock_rb_tree_RB_SCAN(&object->swblock_root, rb_swblock_scancmp, |
| 1945 | swp_pager_meta_free_callback, &info); |
| 1946 | } |
| 1947 | |
| 1948 | static |
| 1949 | int |
| 1950 | swp_pager_meta_free_callback(struct swblock *swap, void *data) |
| 1951 | { |
| 1952 | struct swfreeinfo *info = data; |
| 1953 | vm_object_t object = info->object; |
| 1954 | int index; |
| 1955 | int eindex; |
| 1956 | |
| 1957 | /* |
| 1958 | * Figure out the range within the swblock. The wider scan may |
| 1959 | * return edge-case swap blocks when the start and/or end points |
| 1960 | * are in the middle of a block. |
| 1961 | */ |
| 1962 | if (swap->swb_index < info->begi) |
| 1963 | index = (int)info->begi & SWAP_META_MASK; |
| 1964 | else |
| 1965 | index = 0; |
| 1966 | |
| 1967 | if (swap->swb_index + SWAP_META_PAGES > info->endi) |
| 1968 | eindex = (int)info->endi & SWAP_META_MASK; |
| 1969 | else |
| 1970 | eindex = SWAP_META_MASK; |
| 1971 | |
| 1972 | /* |
| 1973 | * Scan and free the blocks. The loop terminates early |
| 1974 | * if (swap) runs out of blocks and could be freed. |
| 1975 | */ |
| 1976 | while (index <= eindex) { |
| 1977 | daddr_t v = swap->swb_pages[index]; |
| 1978 | |
| 1979 | if (v != SWAPBLK_NONE) { |
| 1980 | swp_pager_freeswapspace(object, v, 1); |
| 1981 | swap->swb_pages[index] = SWAPBLK_NONE; |
| 1982 | if (--swap->swb_count == 0) { |
| 1983 | swp_pager_remove(object, swap); |
| 1984 | zfree(swap_zone, swap); |
| 1985 | --object->swblock_count; |
| 1986 | break; |
| 1987 | } |
| 1988 | } |
| 1989 | ++index; |
| 1990 | } |
| 1991 | /* swap may be invalid here due to zfree above */ |
| 1992 | return(0); |
| 1993 | } |
| 1994 | |
| 1995 | /* |
| 1996 | * SWP_PAGER_META_FREE_ALL() - destroy all swap metadata associated with object |
| 1997 | * |
| 1998 | * This routine locates and destroys all swap metadata associated with |
| 1999 | * an object. |
| 2000 | * |
| 2001 | * This routine must be called at splvm() |
| 2002 | */ |
| 2003 | static void |
| 2004 | swp_pager_meta_free_all(vm_object_t object) |
| 2005 | { |
| 2006 | struct swblock *swap; |
| 2007 | int i; |
| 2008 | |
| 2009 | while ((swap = RB_ROOT(&object->swblock_root)) != NULL) { |
| 2010 | swp_pager_remove(object, swap); |
| 2011 | for (i = 0; i < SWAP_META_PAGES; ++i) { |
| 2012 | daddr_t v = swap->swb_pages[i]; |
| 2013 | if (v != SWAPBLK_NONE) { |
| 2014 | --swap->swb_count; |
| 2015 | swp_pager_freeswapspace(object, v, 1); |
| 2016 | } |
| 2017 | } |
| 2018 | if (swap->swb_count != 0) |
| 2019 | panic("swap_pager_meta_free_all: swb_count != 0"); |
| 2020 | zfree(swap_zone, swap); |
| 2021 | --object->swblock_count; |
| 2022 | } |
| 2023 | KKASSERT(object->swblock_count == 0); |
| 2024 | } |
| 2025 | |
| 2026 | /* |
| 2027 | * SWP_PAGER_METACTL() - misc control of swap and vm_page_t meta data. |
| 2028 | * |
| 2029 | * This routine is capable of looking up, popping, or freeing |
| 2030 | * swapblk assignments in the swap meta data or in the vm_page_t. |
| 2031 | * The routine typically returns the swapblk being looked-up, or popped, |
| 2032 | * or SWAPBLK_NONE if the block was freed, or SWAPBLK_NONE if the block |
| 2033 | * was invalid. This routine will automatically free any invalid |
| 2034 | * meta-data swapblks. |
| 2035 | * |
| 2036 | * It is not possible to store invalid swapblks in the swap meta data |
| 2037 | * (other then a literal 'SWAPBLK_NONE'), so we don't bother checking. |
| 2038 | * |
| 2039 | * When acting on a busy resident page and paging is in progress, we |
| 2040 | * have to wait until paging is complete but otherwise can act on the |
| 2041 | * busy page. |
| 2042 | * |
| 2043 | * This routine must be called at splvm(). |
| 2044 | * |
| 2045 | * SWM_FREE remove and free swap block from metadata |
| 2046 | * SWM_POP remove from meta data but do not free.. pop it out |
| 2047 | */ |
| 2048 | static daddr_t |
| 2049 | swp_pager_meta_ctl(vm_object_t object, vm_pindex_t index, int flags) |
| 2050 | { |
| 2051 | struct swblock *swap; |
| 2052 | daddr_t r1; |
| 2053 | |
| 2054 | if (object->swblock_count == 0) |
| 2055 | return(SWAPBLK_NONE); |
| 2056 | |
| 2057 | r1 = SWAPBLK_NONE; |
| 2058 | swap = swp_pager_lookup(object, index); |
| 2059 | |
| 2060 | if (swap != NULL) { |
| 2061 | index &= SWAP_META_MASK; |
| 2062 | r1 = swap->swb_pages[index]; |
| 2063 | |
| 2064 | if (r1 != SWAPBLK_NONE) { |
| 2065 | if (flags & SWM_FREE) { |
| 2066 | swp_pager_freeswapspace(object, r1, 1); |
| 2067 | r1 = SWAPBLK_NONE; |
| 2068 | } |
| 2069 | if (flags & (SWM_FREE|SWM_POP)) { |
| 2070 | swap->swb_pages[index] = SWAPBLK_NONE; |
| 2071 | if (--swap->swb_count == 0) { |
| 2072 | swp_pager_remove(object, swap); |
| 2073 | zfree(swap_zone, swap); |
| 2074 | --object->swblock_count; |
| 2075 | } |
| 2076 | } |
| 2077 | } |
| 2078 | } |
| 2079 | return(r1); |
| 2080 | } |