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 static  pgo_dealloc_t           dead_pager_dealloc;
  92 static  pgo_getpage_t           dead_pager_getpage;
  93 static  pgo_putpages_t          dead_pager_putpages;
  94 static  pgo_haspage_t           dead_pager_haspage;
  95
  96 static struct pagerops deadpagerops = {
  97         .pgo_dealloc =          dead_pager_dealloc,
  98         .pgo_getpage =          dead_pager_getpage,
  99         .pgo_putpages =         dead_pager_putpages,
 100         .pgo_haspage =          dead_pager_haspage
 101 };
 102
 103 extern struct pagerops defaultpagerops;
 104 extern struct pagerops swappagerops;
 105 extern struct pagerops vnodepagerops;
 106 extern struct pagerops devicepagerops;
 107 extern struct pagerops physpagerops;
 108
 109 /*
 110  * No requirements.
 111  */
 112 static int
 113 dead_pager_getpage(vm_object_t obj, vm_pindex_t pindex,
 114                    vm_page_t *mpp, int seqaccess)
 115 {
 116         return VM_PAGER_FAIL;
 117 }
 118
 119 /*
 120  * No requirements.
 121  */
 122 static void
 123 dead_pager_putpages(vm_object_t object, vm_page_t *m, int count, int flags,
 124                     int *rtvals)
 125 {
 126         int i;
 127
 128         for (i = 0; i < count; i++) {
 129                 rtvals[i] = VM_PAGER_AGAIN;
 130         }
 131 }
 132
 133 /*
 134  * No requirements.
 135  */
 136 static boolean_t
 137 dead_pager_haspage(vm_object_t object, vm_pindex_t pindex)
 138 {
 139         return FALSE;
 140 }
 141
 142 /*
 143  * No requirements.
 144  */
 145 static void
 146 dead_pager_dealloc(vm_object_t object)
 147 {
 148         KKASSERT(object->swblock_count == 0);
 149         return;
 150 }
 151
 152 struct pagerops *pagertab[] = {
 153         &defaultpagerops,       /* OBJT_DEFAULT */
 154         &swappagerops,          /* OBJT_SWAP */
 155         &vnodepagerops,         /* OBJT_VNODE */
 156         &devicepagerops,        /* OBJT_DEVICE */
 157         &devicepagerops,        /* OBJT_MGTDEVICE */
 158         &physpagerops,          /* OBJT_PHYS */
 159         &deadpagerops           /* OBJT_DEAD */
 160 };
 161
 162 int npagers = NELEM(pagertab);
 163
 164 /*
 165  * Kernel address space for mapping pages.
 166  * Used by pagers where KVAs are needed for IO.
 167  *
 168  * XXX needs to be large enough to support the number of pending async
 169  * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size
 170  * (MAXPHYS == 64k) if you want to get the most efficiency.
 171  */
 172 #define PAGER_MAP_SIZE  (8 * 1024 * 1024)
 173
 174 #define BSWHSIZE        16
 175 #define BSWHMASK        (BSWHSIZE - 1)
 176
 177 TAILQ_HEAD(swqueue, buf);
 178
 179 int pager_map_size = PAGER_MAP_SIZE;
 180
 181 static struct vm_map pager_map_store;
 182 struct vm_map *pager_map = &pager_map_store;
 183
 184 static vm_offset_t swapbkva_mem;        /* swap buffers kva */
 185 static vm_offset_t swapbkva_kva;        /* swap buffers kva */
 186 static struct swqueue bswlist_mem[BSWHSIZE];    /* with preallocated memory */
 187 static struct swqueue bswlist_kva[BSWHSIZE];    /* with kva */
 188 static struct swqueue bswlist_raw[BSWHSIZE];    /* without kva */
 189 static struct spinlock bswspin_mem[BSWHSIZE];
 190 static struct spinlock bswspin_kva[BSWHSIZE];
 191 static struct spinlock bswspin_raw[BSWHSIZE];
 192 static int pbuf_raw_count;
 193 static int pbuf_kva_count;
 194 static int pbuf_mem_count;
 195
 196 SYSCTL_INT(_vm, OID_AUTO, pbuf_raw_count, CTLFLAG_RD, &pbuf_raw_count, 0,
 197     "Kernel pbuf raw reservations");
 198 SYSCTL_INT(_vm, OID_AUTO, pbuf_kva_count, CTLFLAG_RD, &pbuf_kva_count, 0,
 199     "Kernel pbuf kva reservations");
 200 SYSCTL_INT(_vm, OID_AUTO, pbuf_mem_count, CTLFLAG_RD, &pbuf_mem_count, 0,
 201     "Kernel pbuf mem reservations");
 202
 203 /*
 204  * Initialize the swap buffer list.
 205  *
 206  * Called from the low level boot code only.
 207  */
 208 static void
 209 vm_pager_init(void *arg __unused)
 210 {
 211         int i;
 212
 213         for (i = 0; i < BSWHSIZE; ++i) {
 214                 TAILQ_INIT(&bswlist_mem[i]);
 215                 TAILQ_INIT(&bswlist_kva[i]);
 216                 TAILQ_INIT(&bswlist_raw[i]);
 217                 spin_init(&bswspin_mem[i], "bswmem");
 218                 spin_init(&bswspin_kva[i], "bswkva");
 219                 spin_init(&bswspin_raw[i], "bswraw");
 220         }
 221 }
 222 SYSINIT(vm_mem, SI_BOOT1_VM, SI_ORDER_SECOND, vm_pager_init, NULL);
 223
 224 /*
 225  * Called from the low level boot code only.
 226  */
 227 static
 228 void
 229 vm_pager_bufferinit(void *dummy __unused)
 230 {
 231         struct buf *bp;
 232         long i;
 233
 234         /*
 235          * Reserve KVM space for pbuf data.
 236          */
 237         swapbkva_mem = kmem_alloc_pageable(pager_map, nswbuf_mem * MAXPHYS,
 238                                            VM_SUBSYS_BUFDATA);
 239         if (!swapbkva_mem)
 240                 panic("Not enough pager_map VM space for physical buffers");
 241         swapbkva_kva = kmem_alloc_pageable(pager_map, nswbuf_kva * MAXPHYS,
 242                                            VM_SUBSYS_BUFDATA);
 243         if (!swapbkva_kva)
 244                 panic("Not enough pager_map VM space for physical buffers");
 245
 246         /*
 247          * Initial pbuf setup.
 248          *
 249          * mem - These pbufs have permanently allocated memory
 250          * kva - These pbufs have unallocated kva reservations
 251          * raw - These pbufs have no kva reservations
 252          */
 253
 254         /*
 255          * Buffers with pre-allocated kernel memory can be convenient for
 256          * copyin/copyout because no SMP page invalidation or other pmap
 257          * operations are needed.
 258          */
 259         bp = swbuf_mem;
 260         for (i = 0; i < nswbuf_mem; ++i, ++bp) {
 261                 vm_page_t m;
 262                 vm_pindex_t pg;
 263                 int j;
 264
 265                 bp->b_kvabase = (caddr_t)((intptr_t)i * MAXPHYS) + swapbkva_mem;
 266                 bp->b_kvasize = MAXPHYS;
 267                 bp->b_swindex = i & BSWHMASK;
 268                 bp->b_cpumask = smp_active_mask;
 269                 BUF_LOCKINIT(bp);
 270                 buf_dep_init(bp);
 271                 TAILQ_INSERT_HEAD(&bswlist_mem[i & BSWHMASK], bp, b_freelist);
 272                 atomic_add_int(&pbuf_mem_count, 1);
 273                 bp->b_data = bp->b_kvabase;
 274                 bp->b_bcount = MAXPHYS;
 275                 bp->b_xio.xio_pages = bp->b_xio.xio_internal_pages;
 276
 277                 pg = (vm_offset_t)bp->b_kvabase >> PAGE_SHIFT;
 278                 vm_object_hold(kernel_object);
 279                 for (j = 0; j < MAXPHYS / PAGE_SIZE; ++j) {
 280                         m = vm_page_alloc(kernel_object, pg, VM_ALLOC_NORMAL |
 281                                                               VM_ALLOC_SYSTEM);
 282                         KKASSERT(m != NULL);
 283                         bp->b_xio.xio_internal_pages[j] = m;
 284                         vm_page_wire(m);
 285                         /* early boot, no other cpus running yet */
 286                         pmap_kenter_noinval(pg * PAGE_SIZE, VM_PAGE_TO_PHYS(m));
 287                         cpu_invlpg((void *)(pg * PAGE_SIZE));
 288                         vm_page_wakeup(m);
 289                         ++pg;
 290                 }
 291                 vm_object_drop(kernel_object);
 292                 bp->b_xio.xio_npages = j;
 293         }
 294
 295         /*
 296          * Buffers with pre-assigned KVA bases.  The KVA has no memory pages
 297          * assigned to it.  Saves the caller from having to reserve KVA for
 298          * the page map.
 299          */
 300         bp = swbuf_kva;
 301         for (i = 0; i < nswbuf_kva; ++i, ++bp) {
 302                 bp->b_kvabase = (caddr_t)((intptr_t)i * MAXPHYS) + swapbkva_kva;
 303                 bp->b_kvasize = MAXPHYS;
 304                 bp->b_swindex = i & BSWHMASK;
 305                 BUF_LOCKINIT(bp);
 306                 buf_dep_init(bp);
 307                 TAILQ_INSERT_HEAD(&bswlist_kva[i & BSWHMASK], bp, b_freelist);
 308                 atomic_add_int(&pbuf_kva_count, 1);
 309         }
 310
 311         /*
 312          * RAW buffers with no KVA mappings.
 313          *
 314          * NOTE: We use KM_NOTLBSYNC here to reduce unnecessary IPIs
 315          *       during startup, which can really slow down emulated
 316          *       systems.
 317          */
 318         nswbuf_raw = nbuf * 2;
 319         swbuf_raw = (void *)kmem_alloc3(kernel_map,
 320                                 round_page(nswbuf_raw * sizeof(struct buf)),
 321                                 VM_SUBSYS_BUFDATA,
 322                                 KM_NOTLBSYNC);
 323         smp_invltlb();
 324         bp = swbuf_raw;
 325         for (i = 0; i < nswbuf_raw; ++i, ++bp) {
 326                 bp->b_swindex = i & BSWHMASK;
 327                 BUF_LOCKINIT(bp);
 328                 buf_dep_init(bp);
 329                 TAILQ_INSERT_HEAD(&bswlist_raw[i & BSWHMASK], bp, b_freelist);
 330                 atomic_add_int(&pbuf_raw_count, 1);
 331         }
 332 }
 333
 334 SYSINIT(do_vmpg, SI_BOOT2_MACHDEP, SI_ORDER_FIRST, vm_pager_bufferinit, NULL);
 335
 336 /*
 337  * No requirements.
 338  */
 339 void
 340 vm_pager_deallocate(vm_object_t object)
 341 {
 342         (*pagertab[object->type]->pgo_dealloc) (object);
 343 }
 344
 345 /*
 346  * vm_pager_get_pages() - inline, see vm/vm_pager.h
 347  * vm_pager_put_pages() - inline, see vm/vm_pager.h
 348  * vm_pager_has_page() - inline, see vm/vm_pager.h
 349  * vm_pager_page_inserted() - inline, see vm/vm_pager.h
 350  * vm_pager_page_removed() - inline, see vm/vm_pager.h
 351  */
 352
 353 /*
 354  * Search the specified pager object list for an object with the
 355  * specified handle.  If an object with the specified handle is found,
 356  * increase its reference count and return it.  Otherwise, return NULL.
 357  *
 358  * The pager object list must be locked.
 359  */
 360 vm_object_t
 361 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
 362 {
 363         vm_object_t object;
 364
 365         TAILQ_FOREACH(object, pg_list, pager_object_entry) {
 366                 if (object->handle == handle) {
 367                         VM_OBJECT_LOCK(object);
 368                         if ((object->flags & OBJ_DEAD) == 0) {
 369                                 vm_object_reference_locked(object);
 370                                 VM_OBJECT_UNLOCK(object);
 371                                 break;
 372                         }
 373                         VM_OBJECT_UNLOCK(object);
 374                 }
 375         }
 376         return (object);
 377 }
 378
 379 /*
 380  * Initialize a physical buffer.
 381  *
 382  * No requirements.
 383  */
 384 static void
 385 initpbuf(struct buf *bp)
 386 {
 387         bp->b_qindex = 0;               /* BQUEUE_NONE */
 388         bp->b_data = bp->b_kvabase;     /* NULL if pbuf sans kva */
 389         bp->b_flags = B_PAGING;
 390         bp->b_cmd = BUF_CMD_DONE;
 391         bp->b_error = 0;
 392         bp->b_bcount = 0;
 393         bp->b_bufsize = MAXPHYS;
 394         initbufbio(bp);
 395         xio_init(&bp->b_xio);
 396         BUF_LOCK(bp, LK_EXCLUSIVE);
 397 }
 398
 399 /*
 400  * Allocate a physical buffer
 401  *
 402  * If (pfreecnt != NULL) then *pfreecnt will be decremented on return and
 403  * the function will block while it is <= 0.
 404  *
 405  * Physical buffers can be with or without KVA space reserved.  There
 406  * are severe limitations on the ones with KVA reserved, and fewer
 407  * limitations on the ones without.  getpbuf() gets one without,
 408  * getpbuf_kva() gets one with.
 409  *
 410  * No requirements.
 411  */
 412 struct buf *
 413 getpbuf(int *pfreecnt)
 414 {
 415         struct buf *bp;
 416         int iter;
 417         int loops;
 418
 419         for (;;) {
 420                 while (pfreecnt && *pfreecnt <= 0) {
 421                         tsleep_interlock(pfreecnt, 0);
 422                         if ((int)atomic_fetchadd_int(pfreecnt, 0) <= 0)
 423                                 tsleep(pfreecnt, PINTERLOCKED, "wswbuf0", 0);
 424                 }
 425                 if (pbuf_raw_count <= 0) {
 426                         tsleep_interlock(&pbuf_raw_count, 0);
 427                         if ((int)atomic_fetchadd_int(&pbuf_raw_count, 0) <= 0)
 428                                 tsleep(&pbuf_raw_count, PINTERLOCKED,
 429                                        "wswbuf1", 0);
 430                         continue;
 431                 }
 432                 iter = mycpuid & BSWHMASK;
 433                 for (loops = BSWHSIZE; loops; --loops) {
 434                         if (TAILQ_FIRST(&bswlist_raw[iter]) == NULL) {
 435                                 iter = (iter + 1) & BSWHMASK;
 436                                 continue;
 437                         }
 438                         spin_lock(&bswspin_raw[iter]);
 439                         if ((bp = TAILQ_FIRST(&bswlist_raw[iter])) == NULL) {
 440                                 spin_unlock(&bswspin_raw[iter]);
 441                                 iter = (iter + 1) & BSWHMASK;
 442                                 continue;
 443                         }
 444                         TAILQ_REMOVE(&bswlist_raw[iter], bp, b_freelist);
 445                         atomic_add_int(&pbuf_raw_count, -1);
 446                         if (pfreecnt)
 447                                 atomic_add_int(pfreecnt, -1);
 448                         spin_unlock(&bswspin_raw[iter]);
 449                         initpbuf(bp);
 450
 451                         return bp;
 452                 }
 453         }
 454         /* not reached */
 455 }
 456
 457 struct buf *
 458 getpbuf_kva(int *pfreecnt)
 459 {
 460         struct buf *bp;
 461         int iter;
 462         int loops;
 463
 464         for (;;) {
 465                 while (pfreecnt && *pfreecnt <= 0) {
 466                         tsleep_interlock(pfreecnt, 0);
 467                         if ((int)atomic_fetchadd_int(pfreecnt, 0) <= 0)
 468                                 tsleep(pfreecnt, PINTERLOCKED, "wswbuf2", 0);
 469                 }
 470                 if (pbuf_kva_count <= 0) {
 471                         tsleep_interlock(&pbuf_kva_count, 0);
 472                         if ((int)atomic_fetchadd_int(&pbuf_kva_count, 0) <= 0)
 473                                 tsleep(&pbuf_kva_count, PINTERLOCKED,
 474                                        "wswbuf3", 0);
 475                         continue;
 476                 }
 477                 iter = mycpuid & BSWHMASK;
 478                 for (loops = BSWHSIZE; loops; --loops) {
 479                         if (TAILQ_FIRST(&bswlist_kva[iter]) == NULL) {
 480                                 iter = (iter + 1) & BSWHMASK;
 481                                 continue;
 482                         }
 483                         spin_lock(&bswspin_kva[iter]);
 484                         if ((bp = TAILQ_FIRST(&bswlist_kva[iter])) == NULL) {
 485                                 spin_unlock(&bswspin_kva[iter]);
 486                                 iter = (iter + 1) & BSWHMASK;
 487                                 continue;
 488                         }
 489                         TAILQ_REMOVE(&bswlist_kva[iter], bp, b_freelist);
 490                         atomic_add_int(&pbuf_kva_count, -1);
 491                         if (pfreecnt)
 492                                 atomic_add_int(pfreecnt, -1);
 493                         spin_unlock(&bswspin_kva[iter]);
 494                         initpbuf(bp);
 495
 496                         return bp;
 497                 }
 498         }
 499         /* not reached */
 500 }
 501
 502 /*
 503  * Allocate a pbuf with kernel memory already preallocated.  Caller must
 504  * not change the mapping.
 505  */
 506 struct buf *
 507 getpbuf_mem(int *pfreecnt)
 508 {
 509         struct buf *bp;
 510         int iter;
 511         int loops;
 512
 513         for (;;) {
 514                 while (pfreecnt && *pfreecnt <= 0) {
 515                         tsleep_interlock(pfreecnt, 0);
 516                         if ((int)atomic_fetchadd_int(pfreecnt, 0) <= 0)
 517                                 tsleep(pfreecnt, PINTERLOCKED, "wswbuf4", 0);
 518                 }
 519                 if (pbuf_mem_count <= 0) {
 520                         tsleep_interlock(&pbuf_mem_count, 0);
 521                         if ((int)atomic_fetchadd_int(&pbuf_mem_count, 0) <= 0)
 522                                 tsleep(&pbuf_mem_count, PINTERLOCKED,
 523                                        "wswbuf5", 0);
 524                         continue;
 525                 }
 526                 iter = mycpuid & BSWHMASK;
 527                 for (loops = BSWHSIZE; loops; --loops) {
 528                         if (TAILQ_FIRST(&bswlist_mem[iter]) == NULL) {
 529                                 iter = (iter + 1) & BSWHMASK;
 530                                 continue;
 531                         }
 532                         spin_lock(&bswspin_mem[iter]);
 533                         if ((bp = TAILQ_FIRST(&bswlist_mem[iter])) == NULL) {
 534                                 spin_unlock(&bswspin_mem[iter]);
 535                                 iter = (iter + 1) & BSWHMASK;
 536                                 continue;
 537                         }
 538                         TAILQ_REMOVE(&bswlist_mem[iter], bp, b_freelist);
 539                         atomic_add_int(&pbuf_mem_count, -1);
 540                         if (pfreecnt)
 541                                 atomic_add_int(pfreecnt, -1);
 542                         spin_unlock(&bswspin_mem[iter]);
 543                         initpbuf(bp);
 544
 545                         return bp;
 546                 }
 547         }
 548         /* not reached */
 549 }
 550
 551 /*
 552  * Allocate a physical buffer, if one is available.
 553  *
 554  * Note that there is no NULL hack here - all subsystems using this
 555  * call are required to use a non-NULL pfreecnt.
 556  *
 557  * No requirements.
 558  */
 559 struct buf *
 560 trypbuf(int *pfreecnt)
 561 {
 562         struct buf *bp;
 563         int iter = mycpuid & BSWHMASK;
 564         int loops;
 565
 566         for (loops = BSWHSIZE; loops; --loops) {
 567                 if (*pfreecnt <= 0 || TAILQ_FIRST(&bswlist_raw[iter]) == NULL) {
 568                         iter = (iter + 1) & BSWHMASK;
 569                         continue;
 570                 }
 571                 spin_lock(&bswspin_raw[iter]);
 572                 if (*pfreecnt <= 0 ||
 573                     (bp = TAILQ_FIRST(&bswlist_raw[iter])) == NULL) {
 574                         spin_unlock(&bswspin_raw[iter]);
 575                         iter = (iter + 1) & BSWHMASK;
 576                         continue;
 577                 }
 578                 TAILQ_REMOVE(&bswlist_raw[iter], bp, b_freelist);
 579                 atomic_add_int(&pbuf_raw_count, -1);
 580                 atomic_add_int(pfreecnt, -1);
 581
 582                 spin_unlock(&bswspin_raw[iter]);
 583
 584                 initpbuf(bp);
 585
 586                 return bp;
 587         }
 588         return NULL;
 589 }
 590
 591 struct buf *
 592 trypbuf_kva(int *pfreecnt)
 593 {
 594         struct buf *bp;
 595         int iter = mycpuid & BSWHMASK;
 596         int loops;
 597
 598         for (loops = BSWHSIZE; loops; --loops) {
 599                 if (*pfreecnt <= 0 || TAILQ_FIRST(&bswlist_kva[iter]) == NULL) {
 600                         iter = (iter + 1) & BSWHMASK;
 601                         continue;
 602                 }
 603                 spin_lock(&bswspin_kva[iter]);
 604                 if (*pfreecnt <= 0 ||
 605                     (bp = TAILQ_FIRST(&bswlist_kva[iter])) == NULL) {
 606                         spin_unlock(&bswspin_kva[iter]);
 607                         iter = (iter + 1) & BSWHMASK;
 608                         continue;
 609                 }
 610                 TAILQ_REMOVE(&bswlist_kva[iter], bp, b_freelist);
 611                 atomic_add_int(&pbuf_kva_count, -1);
 612                 atomic_add_int(pfreecnt, -1);
 613
 614                 spin_unlock(&bswspin_kva[iter]);
 615
 616                 initpbuf(bp);
 617
 618                 return bp;
 619         }
 620         return NULL;
 621 }
 622
 623 /*
 624  * Release a physical buffer
 625  *
 626  *      NOTE: pfreecnt can be NULL, but this 'feature' will be removed
 627  *      relatively soon when the rest of the subsystems get smart about it. XXX
 628  *
 629  * No requirements.
 630  */
 631 void
 632 relpbuf(struct buf *bp, int *pfreecnt)
 633 {
 634         int wake = 0;
 635         int wake_free = 0;
 636         int iter = bp->b_swindex;
 637
 638         KKASSERT(bp->b_flags & B_PAGING);
 639         dsched_buf_exit(bp);
 640
 641         BUF_UNLOCK(bp);
 642
 643         if (bp >= swbuf_mem && bp < &swbuf_mem[nswbuf_mem]) {
 644                 KKASSERT(bp->b_kvabase);
 645                 spin_lock(&bswspin_mem[iter]);
 646                 TAILQ_INSERT_HEAD(&bswlist_mem[iter], bp, b_freelist);
 647                 if (atomic_fetchadd_int(&pbuf_mem_count, 1) == nswbuf_mem / 4)
 648                         wake = 1;
 649                 if (pfreecnt) {
 650                         if (atomic_fetchadd_int(pfreecnt, 1) == 1)
 651                                 wake_free = 1;
 652                 }
 653                 spin_unlock(&bswspin_mem[iter]);
 654                 if (wake)
 655                         wakeup(&pbuf_mem_count);
 656         } else if (bp >= swbuf_kva && bp < &swbuf_kva[nswbuf_kva]) {
 657                 KKASSERT(bp->b_kvabase);
 658                 CPUMASK_ASSZERO(bp->b_cpumask);
 659                 spin_lock(&bswspin_kva[iter]);
 660                 TAILQ_INSERT_HEAD(&bswlist_kva[iter], bp, b_freelist);
 661                 if (atomic_fetchadd_int(&pbuf_kva_count, 1) == nswbuf_kva / 4)
 662                         wake = 1;
 663                 if (pfreecnt) {
 664                         if (atomic_fetchadd_int(pfreecnt, 1) == 1)
 665                                 wake_free = 1;
 666                 }
 667                 spin_unlock(&bswspin_kva[iter]);
 668                 if (wake)
 669                         wakeup(&pbuf_kva_count);
 670         } else {
 671                 KKASSERT(bp->b_kvabase == NULL);
 672                 KKASSERT(bp >= swbuf_raw && bp < &swbuf_raw[nswbuf_raw]);
 673                 CPUMASK_ASSZERO(bp->b_cpumask);
 674                 spin_lock(&bswspin_raw[iter]);
 675                 TAILQ_INSERT_HEAD(&bswlist_raw[iter], bp, b_freelist);
 676                 if (atomic_fetchadd_int(&pbuf_raw_count, 1) == nswbuf_raw / 4)
 677                         wake = 1;
 678                 if (pfreecnt) {
 679                         if (atomic_fetchadd_int(pfreecnt, 1) == 1)
 680                                 wake_free = 1;
 681                 }
 682                 spin_unlock(&bswspin_raw[iter]);
 683                 if (wake)
 684                         wakeup(&pbuf_raw_count);
 685         }
 686         if (wake_free)
 687                 wakeup(pfreecnt);
 688 }
 689
 690 void
 691 pbuf_adjcount(int *pfreecnt, int n)
 692 {
 693         if (n) {
 694                 atomic_add_int(pfreecnt, n);
 695                 wakeup(pfreecnt);
 696         }
 697 }