sys/vm/vm_pager.c

   1 /*
   2  * (MPSAFE)
   3  *
   4  * Copyright (c) 1991, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * The Mach Operating System project at Carnegie-Mellon University.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  *      from: @(#)vm_pager.c    8.6 (Berkeley) 1/12/94
  35  *
  36  *
  37  * Copyright (c) 1987, 1990 Carnegie-Mellon University.
  38  * All rights reserved.
  39  *
  40  * Authors: Avadis Tevanian, Jr., Michael Wayne Young
  41  *
  42  * Permission to use, copy, modify and distribute this software and
  43  * its documentation is hereby granted, provided that both the copyright
  44  * notice and this permission notice appear in all copies of the
  45  * software, derivative works or modified versions, and any portions
  46  * thereof, and that both notices appear in supporting documentation.
  47  *
  48  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  49  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
  50  * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  51  *
  52  * Carnegie Mellon requests users of this software to return to
  53  *
  54  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  55  *  School of Computer Science
  56  *  Carnegie Mellon University
  57  *  Pittsburgh PA 15213-3890
  58  *
  59  * any improvements or extensions that they make and grant Carnegie the
  60  * rights to redistribute these changes.
  61  *
  62  * $FreeBSD: src/sys/vm/vm_pager.c,v 1.54.2.2 2001/11/18 07:11:00 dillon Exp $
  63  */
  64
  65 /*
  66  *      Paging space routine stubs.  Emulates a matchmaker-like interface
  67  *      for builtin pagers.
  68  */
  69
  70 #include <sys/param.h>
  71 #include <sys/systm.h>
  72 #include <sys/kernel.h>
  73 #include <sys/vnode.h>
  74 #include <sys/buf.h>
  75 #include <sys/ucred.h>
  76 #include <sys/dsched.h>
  77 #include <sys/proc.h>
  78 #include <sys/sysctl.h>
  79
  80 #include <vm/vm.h>
  81 #include <vm/vm_param.h>
  82 #include <vm/vm_kern.h>
  83 #include <vm/vm_object.h>
  84 #include <vm/vm_page.h>
  85 #include <vm/vm_pager.h>
  86 #include <vm/vm_extern.h>
  87
  88 #include <sys/buf2.h>
  89 #include <vm/vm_page2.h>
  90
  91 extern struct pagerops defaultpagerops;
  92 extern struct pagerops swappagerops;
  93 extern struct pagerops vnodepagerops;
  94 extern struct pagerops devicepagerops;
  95 extern struct pagerops physpagerops;
  96
  97 static int dead_pager_getpage (vm_object_t, vm_page_t *, int);
  98 static void dead_pager_putpages (vm_object_t, vm_page_t *, int, int, int *);
  99 static boolean_t dead_pager_haspage (vm_object_t, vm_pindex_t);
 100 static void dead_pager_dealloc (vm_object_t);
 101
 102 /*
 103  * No requirements.
 104  */
 105 static int
 106 dead_pager_getpage(vm_object_t obj, vm_page_t *mpp, int seqaccess)
 107 {
 108         return VM_PAGER_FAIL;
 109 }
 110
 111 /*
 112  * No requirements.
 113  */
 114 static void
 115 dead_pager_putpages(vm_object_t object, vm_page_t *m, int count, int flags,
 116                     int *rtvals)
 117 {
 118         int i;
 119
 120         for (i = 0; i < count; i++) {
 121                 rtvals[i] = VM_PAGER_AGAIN;
 122         }
 123 }
 124
 125 /*
 126  * No requirements.
 127  */
 128 static boolean_t
 129 dead_pager_haspage(vm_object_t object, vm_pindex_t pindex)
 130 {
 131         return FALSE;
 132 }
 133
 134 /*
 135  * No requirements.
 136  */
 137 static void
 138 dead_pager_dealloc(vm_object_t object)
 139 {
 140         KKASSERT(object->swblock_count == 0);
 141         return;
 142 }
 143
 144 static struct pagerops deadpagerops = {
 145         dead_pager_dealloc,
 146         dead_pager_getpage,
 147         dead_pager_putpages,
 148         dead_pager_haspage
 149 };
 150
 151 struct pagerops *pagertab[] = {
 152         &defaultpagerops,       /* OBJT_DEFAULT */
 153         &swappagerops,          /* OBJT_SWAP */
 154         &vnodepagerops,         /* OBJT_VNODE */
 155         &devicepagerops,        /* OBJT_DEVICE */
 156         &devicepagerops,        /* OBJT_MGTDEVICE */
 157         &physpagerops,          /* OBJT_PHYS */
 158         &deadpagerops           /* OBJT_DEAD */
 159 };
 160
 161 int npagers = NELEM(pagertab);
 162
 163 /*
 164  * Kernel address space for mapping pages.
 165  * Used by pagers where KVAs are needed for IO.
 166  *
 167  * XXX needs to be large enough to support the number of pending async
 168  * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size
 169  * (MAXPHYS == 64k) if you want to get the most efficiency.
 170  */
 171 #define PAGER_MAP_SIZE  (8 * 1024 * 1024)
 172
 173 #define BSWHSIZE        16
 174 #define BSWHMASK        (BSWHSIZE - 1)
 175
 176 TAILQ_HEAD(swqueue, buf);
 177
 178 int pager_map_size = PAGER_MAP_SIZE;
 179 struct vm_map pager_map;
 180
 181 static vm_offset_t swapbkva_mem;        /* swap buffers kva */
 182 static vm_offset_t swapbkva_kva;        /* swap buffers kva */
 183 static struct swqueue bswlist_mem[BSWHSIZE];    /* with preallocated memory */
 184 static struct swqueue bswlist_kva[BSWHSIZE];    /* with kva */
 185 static struct swqueue bswlist_raw[BSWHSIZE];    /* without kva */
 186 static struct spinlock bswspin_mem[BSWHSIZE];
 187 static struct spinlock bswspin_kva[BSWHSIZE];
 188 static struct spinlock bswspin_raw[BSWHSIZE];
 189 static int pbuf_raw_count;
 190 static int pbuf_kva_count;
 191 static int pbuf_mem_count;
 192
 193 SYSCTL_INT(_vm, OID_AUTO, pbuf_raw_count, CTLFLAG_RD, &pbuf_raw_count, 0,
 194     "Kernel pbuf raw reservations");
 195 SYSCTL_INT(_vm, OID_AUTO, pbuf_kva_count, CTLFLAG_RD, &pbuf_kva_count, 0,
 196     "Kernel pbuf kva reservations");
 197 SYSCTL_INT(_vm, OID_AUTO, pbuf_mem_count, CTLFLAG_RD, &pbuf_mem_count, 0,
 198     "Kernel pbuf mem reservations");
 199
 200 /*
 201  * Initialize the swap buffer list.
 202  *
 203  * Called from the low level boot code only.
 204  */
 205 static void
 206 vm_pager_init(void *arg __unused)
 207 {
 208         int i;
 209
 210         for (i = 0; i < BSWHSIZE; ++i) {
 211                 TAILQ_INIT(&bswlist_mem[i]);
 212                 TAILQ_INIT(&bswlist_kva[i]);
 213                 TAILQ_INIT(&bswlist_raw[i]);
 214                 spin_init(&bswspin_mem[i], "bswmem");
 215                 spin_init(&bswspin_kva[i], "bswkva");
 216                 spin_init(&bswspin_raw[i], "bswraw");
 217         }
 218 }
 219 SYSINIT(vm_mem, SI_BOOT1_VM, SI_ORDER_SECOND, vm_pager_init, NULL);
 220
 221 /*
 222  * Called from the low level boot code only.
 223  */
 224 static
 225 void
 226 vm_pager_bufferinit(void *dummy __unused)
 227 {
 228         struct buf *bp;
 229         long i;
 230
 231         /*
 232          * Reserve KVM space for pbuf data.
 233          */
 234         swapbkva_mem = kmem_alloc_pageable(&pager_map, nswbuf_mem * MAXPHYS,
 235                                            VM_SUBSYS_BUFDATA);
 236         if (!swapbkva_mem)
 237                 panic("Not enough pager_map VM space for physical buffers");
 238         swapbkva_kva = kmem_alloc_pageable(&pager_map, nswbuf_kva * MAXPHYS,
 239                                            VM_SUBSYS_BUFDATA);
 240         if (!swapbkva_kva)
 241                 panic("Not enough pager_map VM space for physical buffers");
 242
 243         /*
 244          * Initial pbuf setup.
 245          *
 246          * mem - These pbufs have permanently allocated memory
 247          * kva - These pbufs have unallocated kva reservations
 248          * raw - These pbufs have no kva reservations
 249          */
 250
 251         /*
 252          * Buffers with pre-allocated kernel memory can be convenient for
 253          * copyin/copyout because no SMP page invalidation or other pmap
 254          * operations are needed.
 255          */
 256         bp = swbuf_mem;
 257         for (i = 0; i < nswbuf_mem; ++i, ++bp) {
 258                 vm_page_t m;
 259                 vm_pindex_t pg;
 260                 int j;
 261
 262                 bp->b_kvabase = (caddr_t)((intptr_t)i * MAXPHYS) + swapbkva_mem;
 263                 bp->b_kvasize = MAXPHYS;
 264                 bp->b_swindex = i & BSWHMASK;
 265                 bp->b_cpumask = smp_active_mask;
 266                 BUF_LOCKINIT(bp);
 267                 buf_dep_init(bp);
 268                 TAILQ_INSERT_HEAD(&bswlist_mem[i & BSWHMASK], bp, b_freelist);
 269                 atomic_add_int(&pbuf_mem_count, 1);
 270                 bp->b_data = bp->b_kvabase;
 271                 bp->b_bcount = MAXPHYS;
 272                 bp->b_xio.xio_pages = bp->b_xio.xio_internal_pages;
 273
 274                 pg = (vm_offset_t)bp->b_kvabase >> PAGE_SHIFT;
 275                 vm_object_hold(&kernel_object);
 276                 for (j = 0; j < MAXPHYS / PAGE_SIZE; ++j) {
 277                         m = vm_page_alloc(&kernel_object, pg, VM_ALLOC_NORMAL |
 278                                                               VM_ALLOC_SYSTEM);
 279                         KKASSERT(m != NULL);
 280                         bp->b_xio.xio_internal_pages[j] = m;
 281                         vm_page_wire(m);
 282                         /* early boot, no other cpus running yet */
 283                         pmap_kenter_noinval(pg * PAGE_SIZE, VM_PAGE_TO_PHYS(m));
 284                         cpu_invlpg((void *)(pg * PAGE_SIZE));
 285                         vm_page_wakeup(m);
 286                         ++pg;
 287                 }
 288                 vm_object_drop(&kernel_object);
 289                 bp->b_xio.xio_npages = j;
 290         }
 291
 292         /*
 293          * Buffers with pre-assigned KVA bases.  The KVA has no memory pages
 294          * assigned to it.  Saves the caller from having to reserve KVA for
 295          * the page map.
 296          */
 297         bp = swbuf_kva;
 298         for (i = 0; i < nswbuf_kva; ++i, ++bp) {
 299                 bp->b_kvabase = (caddr_t)((intptr_t)i * MAXPHYS) + swapbkva_kva;
 300                 bp->b_kvasize = MAXPHYS;
 301                 bp->b_swindex = i & BSWHMASK;
 302                 BUF_LOCKINIT(bp);
 303                 buf_dep_init(bp);
 304                 TAILQ_INSERT_HEAD(&bswlist_kva[i & BSWHMASK], bp, b_freelist);
 305                 atomic_add_int(&pbuf_kva_count, 1);
 306         }
 307
 308         /*
 309          * RAW buffers with no KVA mappings.
 310          *
 311          * NOTE: We use KM_NOTLBSYNC here to reduce unnecessary IPIs
 312          *       during startup, which can really slow down emulated
 313          *       systems.
 314          */
 315         nswbuf_raw = nbuf * 2;
 316         swbuf_raw = (void *)kmem_alloc3(&kernel_map,
 317                                 round_page(nswbuf_raw * sizeof(struct buf)),
 318                                 VM_SUBSYS_BUFDATA,
 319                                 KM_NOTLBSYNC);
 320         smp_invltlb();
 321         bp = swbuf_raw;
 322         for (i = 0; i < nswbuf_raw; ++i, ++bp) {
 323                 bp->b_swindex = i & BSWHMASK;
 324                 BUF_LOCKINIT(bp);
 325                 buf_dep_init(bp);
 326                 TAILQ_INSERT_HEAD(&bswlist_raw[i & BSWHMASK], bp, b_freelist);
 327                 atomic_add_int(&pbuf_raw_count, 1);
 328         }
 329 }
 330
 331 SYSINIT(do_vmpg, SI_BOOT2_MACHDEP, SI_ORDER_FIRST, vm_pager_bufferinit, NULL);
 332
 333 /*
 334  * No requirements.
 335  */
 336 void
 337 vm_pager_deallocate(vm_object_t object)
 338 {
 339         (*pagertab[object->type]->pgo_dealloc) (object);
 340 }
 341
 342 /*
 343  * vm_pager_get_pages() - inline, see vm/vm_pager.h
 344  * vm_pager_put_pages() - inline, see vm/vm_pager.h
 345  * vm_pager_has_page() - inline, see vm/vm_pager.h
 346  * vm_pager_page_inserted() - inline, see vm/vm_pager.h
 347  * vm_pager_page_removed() - inline, see vm/vm_pager.h
 348  */
 349
 350 /*
 351  * Search the specified pager object list for an object with the
 352  * specified handle.  If an object with the specified handle is found,
 353  * increase its reference count and return it.  Otherwise, return NULL.
 354  *
 355  * The pager object list must be locked.
 356  */
 357 vm_object_t
 358 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
 359 {
 360         vm_object_t object;
 361
 362         TAILQ_FOREACH(object, pg_list, pager_object_list) {
 363                 if (object->handle == handle) {
 364                         VM_OBJECT_LOCK(object);
 365                         if ((object->flags & OBJ_DEAD) == 0) {
 366                                 vm_object_reference_locked(object);
 367                                 VM_OBJECT_UNLOCK(object);
 368                                 break;
 369                         }
 370                         VM_OBJECT_UNLOCK(object);
 371                 }
 372         }
 373         return (object);
 374 }
 375
 376 /*
 377  * Initialize a physical buffer.
 378  *
 379  * No requirements.
 380  */
 381 static void
 382 initpbuf(struct buf *bp)
 383 {
 384         bp->b_qindex = 0;               /* BQUEUE_NONE */
 385         bp->b_data = bp->b_kvabase;     /* NULL if pbuf sans kva */
 386         bp->b_flags = B_PAGING;
 387         bp->b_cmd = BUF_CMD_DONE;
 388         bp->b_error = 0;
 389         bp->b_bcount = 0;
 390         bp->b_bufsize = MAXPHYS;
 391         initbufbio(bp);
 392         xio_init(&bp->b_xio);
 393         BUF_LOCK(bp, LK_EXCLUSIVE);
 394 }
 395
 396 /*
 397  * Allocate a physical buffer
 398  *
 399  * If (pfreecnt != NULL) then *pfreecnt will be decremented on return and
 400  * the function will block while it is <= 0.
 401  *
 402  * Physical buffers can be with or without KVA space reserved.  There
 403  * are severe limitations on the ones with KVA reserved, and fewer
 404  * limitations on the ones without.  getpbuf() gets one without,
 405  * getpbuf_kva() gets one with.
 406  *
 407  * No requirements.
 408  */
 409 struct buf *
 410 getpbuf(int *pfreecnt)
 411 {
 412         struct buf *bp;
 413         int iter;
 414         int loops;
 415
 416         for (;;) {
 417                 while (pfreecnt && *pfreecnt <= 0) {
 418                         tsleep_interlock(pfreecnt, 0);
 419                         if ((int)atomic_fetchadd_int(pfreecnt, 0) <= 0)
 420                                 tsleep(pfreecnt, PINTERLOCKED, "wswbuf0", 0);
 421                 }
 422                 if (pbuf_raw_count <= 0) {
 423                         tsleep_interlock(&pbuf_raw_count, 0);
 424                         if ((int)atomic_fetchadd_int(&pbuf_raw_count, 0) <= 0)
 425                                 tsleep(&pbuf_raw_count, PINTERLOCKED,
 426                                        "wswbuf1", 0);
 427                         continue;
 428                 }
 429                 iter = mycpuid & BSWHMASK;
 430                 for (loops = BSWHSIZE; loops; --loops) {
 431                         if (TAILQ_FIRST(&bswlist_raw[iter]) == NULL) {
 432                                 iter = (iter + 1) & BSWHMASK;
 433                                 continue;
 434                         }
 435                         spin_lock(&bswspin_raw[iter]);
 436                         if ((bp = TAILQ_FIRST(&bswlist_raw[iter])) == NULL) {
 437                                 spin_unlock(&bswspin_raw[iter]);
 438                                 iter = (iter + 1) & BSWHMASK;
 439                                 continue;
 440                         }
 441                         TAILQ_REMOVE(&bswlist_raw[iter], bp, b_freelist);
 442                         atomic_add_int(&pbuf_raw_count, -1);
 443                         if (pfreecnt)
 444                                 atomic_add_int(pfreecnt, -1);
 445                         spin_unlock(&bswspin_raw[iter]);
 446                         initpbuf(bp);
 447
 448                         return bp;
 449                 }
 450         }
 451         /* not reached */
 452 }
 453
 454 struct buf *
 455 getpbuf_kva(int *pfreecnt)
 456 {
 457         struct buf *bp;
 458         int iter;
 459         int loops;
 460
 461         for (;;) {
 462                 while (pfreecnt && *pfreecnt <= 0) {
 463                         tsleep_interlock(pfreecnt, 0);
 464                         if ((int)atomic_fetchadd_int(pfreecnt, 0) <= 0)
 465                                 tsleep(pfreecnt, PINTERLOCKED, "wswbuf2", 0);
 466                 }
 467                 if (pbuf_kva_count <= 0) {
 468                         tsleep_interlock(&pbuf_kva_count, 0);
 469                         if ((int)atomic_fetchadd_int(&pbuf_kva_count, 0) <= 0)
 470                                 tsleep(&pbuf_kva_count, PINTERLOCKED,
 471                                        "wswbuf3", 0);
 472                         continue;
 473                 }
 474                 iter = mycpuid & BSWHMASK;
 475                 for (loops = BSWHSIZE; loops; --loops) {
 476                         if (TAILQ_FIRST(&bswlist_kva[iter]) == NULL) {
 477                                 iter = (iter + 1) & BSWHMASK;
 478                                 continue;
 479                         }
 480                         spin_lock(&bswspin_kva[iter]);
 481                         if ((bp = TAILQ_FIRST(&bswlist_kva[iter])) == NULL) {
 482                                 spin_unlock(&bswspin_kva[iter]);
 483                                 iter = (iter + 1) & BSWHMASK;
 484                                 continue;
 485                         }
 486                         TAILQ_REMOVE(&bswlist_kva[iter], bp, b_freelist);
 487                         atomic_add_int(&pbuf_kva_count, -1);
 488                         if (pfreecnt)
 489                                 atomic_add_int(pfreecnt, -1);
 490                         spin_unlock(&bswspin_kva[iter]);
 491                         initpbuf(bp);
 492
 493                         return bp;
 494                 }
 495         }
 496         /* not reached */
 497 }
 498
 499 /*
 500  * Allocate a pbuf with kernel memory already preallocated.  Caller must
 501  * not change the mapping.
 502  */
 503 struct buf *
 504 getpbuf_mem(int *pfreecnt)
 505 {
 506         struct buf *bp;
 507         int iter;
 508         int loops;
 509
 510         for (;;) {
 511                 while (pfreecnt && *pfreecnt <= 0) {
 512                         tsleep_interlock(pfreecnt, 0);
 513                         if ((int)atomic_fetchadd_int(pfreecnt, 0) <= 0)
 514                                 tsleep(pfreecnt, PINTERLOCKED, "wswbuf4", 0);
 515                 }
 516                 if (pbuf_mem_count <= 0) {
 517                         tsleep_interlock(&pbuf_mem_count, 0);
 518                         if ((int)atomic_fetchadd_int(&pbuf_mem_count, 0) <= 0)
 519                                 tsleep(&pbuf_mem_count, PINTERLOCKED,
 520                                        "wswbuf5", 0);
 521                         continue;
 522                 }
 523                 iter = mycpuid & BSWHMASK;
 524                 for (loops = BSWHSIZE; loops; --loops) {
 525                         if (TAILQ_FIRST(&bswlist_mem[iter]) == NULL) {
 526                                 iter = (iter + 1) & BSWHMASK;
 527                                 continue;
 528                         }
 529                         spin_lock(&bswspin_mem[iter]);
 530                         if ((bp = TAILQ_FIRST(&bswlist_mem[iter])) == NULL) {
 531                                 spin_unlock(&bswspin_mem[iter]);
 532                                 iter = (iter + 1) & BSWHMASK;
 533                                 continue;
 534                         }
 535                         TAILQ_REMOVE(&bswlist_mem[iter], bp, b_freelist);
 536                         atomic_add_int(&pbuf_mem_count, -1);
 537                         if (pfreecnt)
 538                                 atomic_add_int(pfreecnt, -1);
 539                         spin_unlock(&bswspin_mem[iter]);
 540                         initpbuf(bp);
 541
 542                         return bp;
 543                 }
 544         }
 545         /* not reached */
 546 }
 547
 548 /*
 549  * Allocate a physical buffer, if one is available.
 550  *
 551  * Note that there is no NULL hack here - all subsystems using this
 552  * call are required to use a non-NULL pfreecnt.
 553  *
 554  * No requirements.
 555  */
 556 struct buf *
 557 trypbuf(int *pfreecnt)
 558 {
 559         struct buf *bp;
 560         int iter = mycpuid & BSWHMASK;
 561         int loops;
 562
 563         for (loops = BSWHSIZE; loops; --loops) {
 564                 if (*pfreecnt <= 0 || TAILQ_FIRST(&bswlist_raw[iter]) == NULL) {
 565                         iter = (iter + 1) & BSWHMASK;
 566                         continue;
 567                 }
 568                 spin_lock(&bswspin_raw[iter]);
 569                 if (*pfreecnt <= 0 ||
 570                     (bp = TAILQ_FIRST(&bswlist_raw[iter])) == NULL) {
 571                         spin_unlock(&bswspin_raw[iter]);
 572                         iter = (iter + 1) & BSWHMASK;
 573                         continue;
 574                 }
 575                 TAILQ_REMOVE(&bswlist_raw[iter], bp, b_freelist);
 576                 atomic_add_int(&pbuf_raw_count, -1);
 577                 atomic_add_int(pfreecnt, -1);
 578
 579                 spin_unlock(&bswspin_raw[iter]);
 580
 581                 initpbuf(bp);
 582
 583                 return bp;
 584         }
 585         return NULL;
 586 }
 587
 588 struct buf *
 589 trypbuf_kva(int *pfreecnt)
 590 {
 591         struct buf *bp;
 592         int iter = mycpuid & BSWHMASK;
 593         int loops;
 594
 595         for (loops = BSWHSIZE; loops; --loops) {
 596                 if (*pfreecnt <= 0 || TAILQ_FIRST(&bswlist_kva[iter]) == NULL) {
 597                         iter = (iter + 1) & BSWHMASK;
 598                         continue;
 599                 }
 600                 spin_lock(&bswspin_kva[iter]);
 601                 if (*pfreecnt <= 0 ||
 602                     (bp = TAILQ_FIRST(&bswlist_kva[iter])) == NULL) {
 603                         spin_unlock(&bswspin_kva[iter]);
 604                         iter = (iter + 1) & BSWHMASK;
 605                         continue;
 606                 }
 607                 TAILQ_REMOVE(&bswlist_kva[iter], bp, b_freelist);
 608                 atomic_add_int(&pbuf_kva_count, -1);
 609                 atomic_add_int(pfreecnt, -1);
 610
 611                 spin_unlock(&bswspin_kva[iter]);
 612
 613                 initpbuf(bp);
 614
 615                 return bp;
 616         }
 617         return NULL;
 618 }
 619
 620 /*
 621  * Release a physical buffer
 622  *
 623  *      NOTE: pfreecnt can be NULL, but this 'feature' will be removed
 624  *      relatively soon when the rest of the subsystems get smart about it. XXX
 625  *
 626  * No requirements.
 627  */
 628 void
 629 relpbuf(struct buf *bp, int *pfreecnt)
 630 {
 631         int wake = 0;
 632         int wake_free = 0;
 633         int iter = bp->b_swindex;
 634
 635         KKASSERT(bp->b_flags & B_PAGING);
 636         dsched_buf_exit(bp);
 637
 638         BUF_UNLOCK(bp);
 639
 640         if (bp >= swbuf_mem && bp < &swbuf_mem[nswbuf_mem]) {
 641                 KKASSERT(bp->b_kvabase);
 642                 spin_lock(&bswspin_mem[iter]);
 643                 TAILQ_INSERT_HEAD(&bswlist_mem[iter], bp, b_freelist);
 644                 if (atomic_fetchadd_int(&pbuf_mem_count, 1) == nswbuf_mem / 4)
 645                         wake = 1;
 646                 if (pfreecnt) {
 647                         if (atomic_fetchadd_int(pfreecnt, 1) == 1)
 648                                 wake_free = 1;
 649                 }
 650                 spin_unlock(&bswspin_mem[iter]);
 651                 if (wake)
 652                         wakeup(&pbuf_mem_count);
 653         } else if (bp >= swbuf_kva && bp < &swbuf_kva[nswbuf_kva]) {
 654                 KKASSERT(bp->b_kvabase);
 655                 CPUMASK_ASSZERO(bp->b_cpumask);
 656                 spin_lock(&bswspin_kva[iter]);
 657                 TAILQ_INSERT_HEAD(&bswlist_kva[iter], bp, b_freelist);
 658                 if (atomic_fetchadd_int(&pbuf_kva_count, 1) == nswbuf_kva / 4)
 659                         wake = 1;
 660                 if (pfreecnt) {
 661                         if (atomic_fetchadd_int(pfreecnt, 1) == 1)
 662                                 wake_free = 1;
 663                 }
 664                 spin_unlock(&bswspin_kva[iter]);
 665                 if (wake)
 666                         wakeup(&pbuf_kva_count);
 667         } else {
 668                 KKASSERT(bp->b_kvabase == NULL);
 669                 KKASSERT(bp >= swbuf_raw && bp < &swbuf_raw[nswbuf_raw]);
 670                 CPUMASK_ASSZERO(bp->b_cpumask);
 671                 spin_lock(&bswspin_raw[iter]);
 672                 TAILQ_INSERT_HEAD(&bswlist_raw[iter], bp, b_freelist);
 673                 if (atomic_fetchadd_int(&pbuf_raw_count, 1) == nswbuf_raw / 4)
 674                         wake = 1;
 675                 if (pfreecnt) {
 676                         if (atomic_fetchadd_int(pfreecnt, 1) == 1)
 677                                 wake_free = 1;
 678                 }
 679                 spin_unlock(&bswspin_raw[iter]);
 680                 if (wake)
 681                         wakeup(&pbuf_raw_count);
 682         }
 683         if (wake_free)
 684                 wakeup(pfreecnt);
 685 }
 686
 687 void
 688 pbuf_adjcount(int *pfreecnt, int n)
 689 {
 690         if (n) {
 691                 atomic_add_int(pfreecnt, n);
 692                 wakeup(pfreecnt);
 693         }
 694 }