sys/vm/vnode_pager.c

   1 /*-
   2  * Copyright (c) 1990 University of Utah.
   3  * Copyright (c) 1991 The Regents of the University of California.
   4  * All rights reserved.
   5  * Copyright (c) 1993, 1994 John S. Dyson
   6  * Copyright (c) 1995, David Greenman
   7  *
   8  * This code is derived from software contributed to Berkeley by
   9  * the Systems Programming Group of the University of Utah Computer
  10  * Science Department.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. All advertising materials mentioning features or use of this software
  21  *    must display the following acknowledgement:
  22  *      This product includes software developed by the University of
  23  *      California, Berkeley and its contributors.
  24  * 4. Neither the name of the University nor the names of its contributors
  25  *    may be used to endorse or promote products derived from this software
  26  *    without specific prior written permission.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  38  * SUCH DAMAGE.
  39  *
  40  *      from: @(#)vnode_pager.c 7.5 (Berkeley) 4/20/91
  41  */
  42
  43 /*
  44  * Page to/from files (vnodes).
  45  */
  46
  47 /*
  48  * TODO:
  49  *      Implement VOP_GETPAGES/PUTPAGES interface for filesystems. Will
  50  *      greatly re-simplify the vnode_pager.
  51  */
  52
  53 #include <sys/cdefs.h>
  54 __FBSDID("$FreeBSD$");
  55
  56 #include "opt_vm.h"
  57
  58 #include <sys/param.h>
  59 #include <sys/systm.h>
  60 #include <sys/proc.h>
  61 #include <sys/vnode.h>
  62 #include <sys/mount.h>
  63 #include <sys/bio.h>
  64 #include <sys/buf.h>
  65 #include <sys/vmmeter.h>
  66 #include <sys/limits.h>
  67 #include <sys/conf.h>
  68 #include <sys/rwlock.h>
  69 #include <sys/sf_buf.h>
  70
  71 #include <machine/atomic.h>
  72
  73 #include <vm/vm.h>
  74 #include <vm/vm_param.h>
  75 #include <vm/vm_object.h>
  76 #include <vm/vm_page.h>
  77 #include <vm/vm_pager.h>
  78 #include <vm/vm_map.h>
  79 #include <vm/vnode_pager.h>
  80 #include <vm/vm_extern.h>
  81
  82 static int vnode_pager_addr(struct vnode *vp, vm_ooffset_t address,
  83     daddr_t *rtaddress, int *run);
  84 static int vnode_pager_input_smlfs(vm_object_t object, vm_page_t m);
  85 static int vnode_pager_input_old(vm_object_t object, vm_page_t m);
  86 static void vnode_pager_dealloc(vm_object_t);
  87 static int vnode_pager_local_getpages0(struct vnode *, vm_page_t *, int, int,
  88     vop_getpages_iodone_t, void *);
  89 static int vnode_pager_getpages(vm_object_t, vm_page_t *, int, int);
  90 static int vnode_pager_getpages_async(vm_object_t, vm_page_t *, int, int,
  91     vop_getpages_iodone_t, void *);
  92 static void vnode_pager_putpages(vm_object_t, vm_page_t *, int, int, int *);
  93 static boolean_t vnode_pager_haspage(vm_object_t, vm_pindex_t, int *, int *);
  94 static vm_object_t vnode_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
  95     vm_ooffset_t, struct ucred *cred);
  96 static int vnode_pager_generic_getpages_done(struct buf *);
  97 static void vnode_pager_generic_getpages_done_async(struct buf *);
  98
  99 struct pagerops vnodepagerops = {
 100         .pgo_alloc =    vnode_pager_alloc,
 101         .pgo_dealloc =  vnode_pager_dealloc,
 102         .pgo_getpages = vnode_pager_getpages,
 103         .pgo_getpages_async = vnode_pager_getpages_async,
 104         .pgo_putpages = vnode_pager_putpages,
 105         .pgo_haspage =  vnode_pager_haspage,
 106 };
 107
 108 int vnode_pbuf_freecnt;
 109 int vnode_async_pbuf_freecnt;
 110
 111 /* Create the VM system backing object for this vnode */
 112 int
 113 vnode_create_vobject(struct vnode *vp, off_t isize, struct thread *td)
 114 {
 115         vm_object_t object;
 116         vm_ooffset_t size = isize;
 117         struct vattr va;
 118
 119         if (!vn_isdisk(vp, NULL) && vn_canvmio(vp) == FALSE)
 120                 return (0);
 121
 122         while ((object = vp->v_object) != NULL) {
 123                 VM_OBJECT_WLOCK(object);
 124                 if (!(object->flags & OBJ_DEAD)) {
 125                         VM_OBJECT_WUNLOCK(object);
 126                         return (0);
 127                 }
 128                 VOP_UNLOCK(vp, 0);
 129                 vm_object_set_flag(object, OBJ_DISCONNECTWNT);
 130                 VM_OBJECT_SLEEP(object, object, PDROP | PVM, "vodead", 0);
 131                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 132         }
 133
 134         if (size == 0) {
 135                 if (vn_isdisk(vp, NULL)) {
 136                         size = IDX_TO_OFF(INT_MAX);
 137                 } else {
 138                         if (VOP_GETATTR(vp, &va, td->td_ucred))
 139                                 return (0);
 140                         size = va.va_size;
 141                 }
 142         }
 143
 144         object = vnode_pager_alloc(vp, size, 0, 0, td->td_ucred);
 145         /*
 146          * Dereference the reference we just created.  This assumes
 147          * that the object is associated with the vp.
 148          */
 149         VM_OBJECT_WLOCK(object);
 150         object->ref_count--;
 151         VM_OBJECT_WUNLOCK(object);
 152         vrele(vp);
 153
 154         KASSERT(vp->v_object != NULL, ("vnode_create_vobject: NULL object"));
 155
 156         return (0);
 157 }
 158
 159 void
 160 vnode_destroy_vobject(struct vnode *vp)
 161 {
 162         struct vm_object *obj;
 163
 164         obj = vp->v_object;
 165         if (obj == NULL)
 166                 return;
 167         ASSERT_VOP_ELOCKED(vp, "vnode_destroy_vobject");
 168         VM_OBJECT_WLOCK(obj);
 169         if (obj->ref_count == 0) {
 170                 /*
 171                  * don't double-terminate the object
 172                  */
 173                 if ((obj->flags & OBJ_DEAD) == 0)
 174                         vm_object_terminate(obj);
 175                 else
 176                         VM_OBJECT_WUNLOCK(obj);
 177         } else {
 178                 /*
 179                  * Woe to the process that tries to page now :-).
 180                  */
 181                 vm_pager_deallocate(obj);
 182                 VM_OBJECT_WUNLOCK(obj);
 183         }
 184         vp->v_object = NULL;
 185 }
 186
 187
 188 /*
 189  * Allocate (or lookup) pager for a vnode.
 190  * Handle is a vnode pointer.
 191  *
 192  * MPSAFE
 193  */
 194 vm_object_t
 195 vnode_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
 196     vm_ooffset_t offset, struct ucred *cred)
 197 {
 198         vm_object_t object;
 199         struct vnode *vp;
 200
 201         /*
 202          * Pageout to vnode, no can do yet.
 203          */
 204         if (handle == NULL)
 205                 return (NULL);
 206
 207         vp = (struct vnode *) handle;
 208
 209         /*
 210          * If the object is being terminated, wait for it to
 211          * go away.
 212          */
 213 retry:
 214         while ((object = vp->v_object) != NULL) {
 215                 VM_OBJECT_WLOCK(object);
 216                 if ((object->flags & OBJ_DEAD) == 0)
 217                         break;
 218                 vm_object_set_flag(object, OBJ_DISCONNECTWNT);
 219                 VM_OBJECT_SLEEP(object, object, PDROP | PVM, "vadead", 0);
 220         }
 221
 222         KASSERT(vp->v_usecount != 0, ("vnode_pager_alloc: no vnode reference"));
 223
 224         if (object == NULL) {
 225                 /*
 226                  * Add an object of the appropriate size
 227                  */
 228                 object = vm_object_allocate(OBJT_VNODE, OFF_TO_IDX(round_page(size)));
 229
 230                 object->un_pager.vnp.vnp_size = size;
 231                 object->un_pager.vnp.writemappings = 0;
 232
 233                 object->handle = handle;
 234                 VI_LOCK(vp);
 235                 if (vp->v_object != NULL) {
 236                         /*
 237                          * Object has been created while we were sleeping
 238                          */
 239                         VI_UNLOCK(vp);
 240                         VM_OBJECT_WLOCK(object);
 241                         KASSERT(object->ref_count == 1,
 242                             ("leaked ref %p %d", object, object->ref_count));
 243                         object->type = OBJT_DEAD;
 244                         object->ref_count = 0;
 245                         VM_OBJECT_WUNLOCK(object);
 246                         vm_object_destroy(object);
 247                         goto retry;
 248                 }
 249                 vp->v_object = object;
 250                 VI_UNLOCK(vp);
 251         } else {
 252                 object->ref_count++;
 253 #if VM_NRESERVLEVEL > 0
 254                 vm_object_color(object, 0);
 255 #endif
 256                 VM_OBJECT_WUNLOCK(object);
 257         }
 258         vref(vp);
 259         return (object);
 260 }
 261
 262 /*
 263  *      The object must be locked.
 264  */
 265 static void
 266 vnode_pager_dealloc(vm_object_t object)
 267 {
 268         struct vnode *vp;
 269         int refs;
 270
 271         vp = object->handle;
 272         if (vp == NULL)
 273                 panic("vnode_pager_dealloc: pager already dealloced");
 274
 275         VM_OBJECT_ASSERT_WLOCKED(object);
 276         vm_object_pip_wait(object, "vnpdea");
 277         refs = object->ref_count;
 278
 279         object->handle = NULL;
 280         object->type = OBJT_DEAD;
 281         if (object->flags & OBJ_DISCONNECTWNT) {
 282                 vm_object_clear_flag(object, OBJ_DISCONNECTWNT);
 283                 wakeup(object);
 284         }
 285         ASSERT_VOP_ELOCKED(vp, "vnode_pager_dealloc");
 286         if (object->un_pager.vnp.writemappings > 0) {
 287                 object->un_pager.vnp.writemappings = 0;
 288                 VOP_ADD_WRITECOUNT(vp, -1);
 289                 CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
 290                     __func__, vp, vp->v_writecount);
 291         }
 292         vp->v_object = NULL;
 293         VOP_UNSET_TEXT(vp);
 294         VM_OBJECT_WUNLOCK(object);
 295         while (refs-- > 0)
 296                 vunref(vp);
 297         VM_OBJECT_WLOCK(object);
 298 }
 299
 300 static boolean_t
 301 vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
 302     int *after)
 303 {
 304         struct vnode *vp = object->handle;
 305         daddr_t bn;
 306         int err;
 307         daddr_t reqblock;
 308         int poff;
 309         int bsize;
 310         int pagesperblock, blocksperpage;
 311
 312         VM_OBJECT_ASSERT_WLOCKED(object);
 313         /*
 314          * If no vp or vp is doomed or marked transparent to VM, we do not
 315          * have the page.
 316          */
 317         if (vp == NULL || vp->v_iflag & VI_DOOMED)
 318                 return FALSE;
 319         /*
 320          * If the offset is beyond end of file we do
 321          * not have the page.
 322          */
 323         if (IDX_TO_OFF(pindex) >= object->un_pager.vnp.vnp_size)
 324                 return FALSE;
 325
 326         bsize = vp->v_mount->mnt_stat.f_iosize;
 327         pagesperblock = bsize / PAGE_SIZE;
 328         blocksperpage = 0;
 329         if (pagesperblock > 0) {
 330                 reqblock = pindex / pagesperblock;
 331         } else {
 332                 blocksperpage = (PAGE_SIZE / bsize);
 333                 reqblock = pindex * blocksperpage;
 334         }
 335         VM_OBJECT_WUNLOCK(object);
 336         err = VOP_BMAP(vp, reqblock, NULL, &bn, after, before);
 337         VM_OBJECT_WLOCK(object);
 338         if (err)
 339                 return TRUE;
 340         if (bn == -1)
 341                 return FALSE;
 342         if (pagesperblock > 0) {
 343                 poff = pindex - (reqblock * pagesperblock);
 344                 if (before) {
 345                         *before *= pagesperblock;
 346                         *before += poff;
 347                 }
 348                 if (after) {
 349                         /*
 350                          * The BMAP vop can report a partial block in the
 351                          * 'after', but must not report blocks after EOF.
 352                          * Assert the latter, and truncate 'after' in case
 353                          * of the former.
 354                          */
 355                         KASSERT((reqblock + *after) * pagesperblock <
 356                             roundup2(object->size, pagesperblock),
 357                             ("%s: reqblock %jd after %d size %ju", __func__,
 358                             (intmax_t )reqblock, *after,
 359                             (uintmax_t )object->size));
 360                         *after *= pagesperblock;
 361                         *after += pagesperblock - (poff + 1);
 362                         if (pindex + *after >= object->size)
 363                                 *after = object->size - 1 - pindex;
 364                 }
 365         } else {
 366                 if (before) {
 367                         *before /= blocksperpage;
 368                 }
 369
 370                 if (after) {
 371                         *after /= blocksperpage;
 372                 }
 373         }
 374         return TRUE;
 375 }
 376
 377 /*
 378  * Lets the VM system know about a change in size for a file.
 379  * We adjust our own internal size and flush any cached pages in
 380  * the associated object that are affected by the size change.
 381  *
 382  * Note: this routine may be invoked as a result of a pager put
 383  * operation (possibly at object termination time), so we must be careful.
 384  */
 385 void
 386 vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize)
 387 {
 388         vm_object_t object;
 389         vm_page_t m;
 390         vm_pindex_t nobjsize;
 391
 392         if ((object = vp->v_object) == NULL)
 393                 return;
 394 /*      ASSERT_VOP_ELOCKED(vp, "vnode_pager_setsize and not locked vnode"); */
 395         VM_OBJECT_WLOCK(object);
 396         if (object->type == OBJT_DEAD) {
 397                 VM_OBJECT_WUNLOCK(object);
 398                 return;
 399         }
 400         KASSERT(object->type == OBJT_VNODE,
 401             ("not vnode-backed object %p", object));
 402         if (nsize == object->un_pager.vnp.vnp_size) {
 403                 /*
 404                  * Hasn't changed size
 405                  */
 406                 VM_OBJECT_WUNLOCK(object);
 407                 return;
 408         }
 409         nobjsize = OFF_TO_IDX(nsize + PAGE_MASK);
 410         if (nsize < object->un_pager.vnp.vnp_size) {
 411                 /*
 412                  * File has shrunk. Toss any cached pages beyond the new EOF.
 413                  */
 414                 if (nobjsize < object->size)
 415                         vm_object_page_remove(object, nobjsize, object->size,
 416                             0);
 417                 /*
 418                  * this gets rid of garbage at the end of a page that is now
 419                  * only partially backed by the vnode.
 420                  *
 421                  * XXX for some reason (I don't know yet), if we take a
 422                  * completely invalid page and mark it partially valid
 423                  * it can screw up NFS reads, so we don't allow the case.
 424                  */
 425                 if ((nsize & PAGE_MASK) &&
 426                     (m = vm_page_lookup(object, OFF_TO_IDX(nsize))) != NULL &&
 427                     m->valid != 0) {
 428                         int base = (int)nsize & PAGE_MASK;
 429                         int size = PAGE_SIZE - base;
 430
 431                         /*
 432                          * Clear out partial-page garbage in case
 433                          * the page has been mapped.
 434                          */
 435                         pmap_zero_page_area(m, base, size);
 436
 437                         /*
 438                          * Update the valid bits to reflect the blocks that
 439                          * have been zeroed.  Some of these valid bits may
 440                          * have already been set.
 441                          */
 442                         vm_page_set_valid_range(m, base, size);
 443
 444                         /*
 445                          * Round "base" to the next block boundary so that the
 446                          * dirty bit for a partially zeroed block is not
 447                          * cleared.
 448                          */
 449                         base = roundup2(base, DEV_BSIZE);
 450
 451                         /*
 452                          * Clear out partial-page dirty bits.
 453                          *
 454                          * note that we do not clear out the valid
 455                          * bits.  This would prevent bogus_page
 456                          * replacement from working properly.
 457                          */
 458                         vm_page_clear_dirty(m, base, PAGE_SIZE - base);
 459                 } else if ((nsize & PAGE_MASK) &&
 460                     vm_page_is_cached(object, OFF_TO_IDX(nsize))) {
 461                         vm_page_cache_free(object, OFF_TO_IDX(nsize),
 462                             nobjsize);
 463                 }
 464         }
 465         object->un_pager.vnp.vnp_size = nsize;
 466         object->size = nobjsize;
 467         VM_OBJECT_WUNLOCK(object);
 468 }
 469
 470 /*
 471  * calculate the linear (byte) disk address of specified virtual
 472  * file address
 473  */
 474 static int
 475 vnode_pager_addr(struct vnode *vp, vm_ooffset_t address, daddr_t *rtaddress,
 476     int *run)
 477 {
 478         int bsize;
 479         int err;
 480         daddr_t vblock;
 481         daddr_t voffset;
 482
 483         if (address < 0)
 484                 return -1;
 485
 486         if (vp->v_iflag & VI_DOOMED)
 487                 return -1;
 488
 489         bsize = vp->v_mount->mnt_stat.f_iosize;
 490         vblock = address / bsize;
 491         voffset = address % bsize;
 492
 493         err = VOP_BMAP(vp, vblock, NULL, rtaddress, run, NULL);
 494         if (err == 0) {
 495                 if (*rtaddress != -1)
 496                         *rtaddress += voffset / DEV_BSIZE;
 497                 if (run) {
 498                         *run += 1;
 499                         *run *= bsize/PAGE_SIZE;
 500                         *run -= voffset/PAGE_SIZE;
 501                 }
 502         }
 503
 504         return (err);
 505 }
 506
 507 /*
 508  * small block filesystem vnode pager input
 509  */
 510 static int
 511 vnode_pager_input_smlfs(vm_object_t object, vm_page_t m)
 512 {
 513         struct vnode *vp;
 514         struct bufobj *bo;
 515         struct buf *bp;
 516         struct sf_buf *sf;
 517         daddr_t fileaddr;
 518         vm_offset_t bsize;
 519         vm_page_bits_t bits;
 520         int error, i;
 521
 522         error = 0;
 523         vp = object->handle;
 524         if (vp->v_iflag & VI_DOOMED)
 525                 return VM_PAGER_BAD;
 526
 527         bsize = vp->v_mount->mnt_stat.f_iosize;
 528
 529         VOP_BMAP(vp, 0, &bo, 0, NULL, NULL);
 530
 531         sf = sf_buf_alloc(m, 0);
 532
 533         for (i = 0; i < PAGE_SIZE / bsize; i++) {
 534                 vm_ooffset_t address;
 535
 536                 bits = vm_page_bits(i * bsize, bsize);
 537                 if (m->valid & bits)
 538                         continue;
 539
 540                 address = IDX_TO_OFF(m->pindex) + i * bsize;
 541                 if (address >= object->un_pager.vnp.vnp_size) {
 542                         fileaddr = -1;
 543                 } else {
 544                         error = vnode_pager_addr(vp, address, &fileaddr, NULL);
 545                         if (error)
 546                                 break;
 547                 }
 548                 if (fileaddr != -1) {
 549                         bp = getpbuf(&vnode_pbuf_freecnt);
 550
 551                         /* build a minimal buffer header */
 552                         bp->b_iocmd = BIO_READ;
 553                         bp->b_iodone = bdone;
 554                         KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
 555                         KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
 556                         bp->b_rcred = crhold(curthread->td_ucred);
 557                         bp->b_wcred = crhold(curthread->td_ucred);
 558                         bp->b_data = (caddr_t)sf_buf_kva(sf) + i * bsize;
 559                         bp->b_blkno = fileaddr;
 560                         pbgetbo(bo, bp);
 561                         bp->b_vp = vp;
 562                         bp->b_bcount = bsize;
 563                         bp->b_bufsize = bsize;
 564                         bp->b_runningbufspace = bp->b_bufsize;
 565                         atomic_add_long(&runningbufspace, bp->b_runningbufspace);
 566
 567                         /* do the input */
 568                         bp->b_iooffset = dbtob(bp->b_blkno);
 569                         bstrategy(bp);
 570
 571                         bwait(bp, PVM, "vnsrd");
 572
 573                         if ((bp->b_ioflags & BIO_ERROR) != 0)
 574                                 error = EIO;
 575
 576                         /*
 577                          * free the buffer header back to the swap buffer pool
 578                          */
 579                         bp->b_vp = NULL;
 580                         pbrelbo(bp);
 581                         relpbuf(bp, &vnode_pbuf_freecnt);
 582                         if (error)
 583                                 break;
 584                 } else
 585                         bzero((caddr_t)sf_buf_kva(sf) + i * bsize, bsize);
 586                 KASSERT((m->dirty & bits) == 0,
 587                     ("vnode_pager_input_smlfs: page %p is dirty", m));
 588                 VM_OBJECT_WLOCK(object);
 589                 m->valid |= bits;
 590                 VM_OBJECT_WUNLOCK(object);
 591         }
 592         sf_buf_free(sf);
 593         if (error) {
 594                 return VM_PAGER_ERROR;
 595         }
 596         return VM_PAGER_OK;
 597 }
 598
 599 /*
 600  * old style vnode pager input routine
 601  */
 602 static int
 603 vnode_pager_input_old(vm_object_t object, vm_page_t m)
 604 {
 605         struct uio auio;
 606         struct iovec aiov;
 607         int error;
 608         int size;
 609         struct sf_buf *sf;
 610         struct vnode *vp;
 611
 612         VM_OBJECT_ASSERT_WLOCKED(object);
 613         error = 0;
 614
 615         /*
 616          * Return failure if beyond current EOF
 617          */
 618         if (IDX_TO_OFF(m->pindex) >= object->un_pager.vnp.vnp_size) {
 619                 return VM_PAGER_BAD;
 620         } else {
 621                 size = PAGE_SIZE;
 622                 if (IDX_TO_OFF(m->pindex) + size > object->un_pager.vnp.vnp_size)
 623                         size = object->un_pager.vnp.vnp_size - IDX_TO_OFF(m->pindex);
 624                 vp = object->handle;
 625                 VM_OBJECT_WUNLOCK(object);
 626
 627                 /*
 628                  * Allocate a kernel virtual address and initialize so that
 629                  * we can use VOP_READ/WRITE routines.
 630                  */
 631                 sf = sf_buf_alloc(m, 0);
 632
 633                 aiov.iov_base = (caddr_t)sf_buf_kva(sf);
 634                 aiov.iov_len = size;
 635                 auio.uio_iov = &aiov;
 636                 auio.uio_iovcnt = 1;
 637                 auio.uio_offset = IDX_TO_OFF(m->pindex);
 638                 auio.uio_segflg = UIO_SYSSPACE;
 639                 auio.uio_rw = UIO_READ;
 640                 auio.uio_resid = size;
 641                 auio.uio_td = curthread;
 642
 643                 error = VOP_READ(vp, &auio, 0, curthread->td_ucred);
 644                 if (!error) {
 645                         int count = size - auio.uio_resid;
 646
 647                         if (count == 0)
 648                                 error = EINVAL;
 649                         else if (count != PAGE_SIZE)
 650                                 bzero((caddr_t)sf_buf_kva(sf) + count,
 651                                     PAGE_SIZE - count);
 652                 }
 653                 sf_buf_free(sf);
 654
 655                 VM_OBJECT_WLOCK(object);
 656         }
 657         KASSERT(m->dirty == 0, ("vnode_pager_input_old: page %p is dirty", m));
 658         if (!error)
 659                 m->valid = VM_PAGE_BITS_ALL;
 660         return error ? VM_PAGER_ERROR : VM_PAGER_OK;
 661 }
 662
 663 /*
 664  * generic vnode pager input routine
 665  */
 666
 667 /*
 668  * Local media VFS's that do not implement their own VOP_GETPAGES
 669  * should have their VOP_GETPAGES call to vnode_pager_generic_getpages()
 670  * to implement the previous behaviour.
 671  *
 672  * All other FS's should use the bypass to get to the local media
 673  * backing vp's VOP_GETPAGES.
 674  */
 675 static int
 676 vnode_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
 677 {
 678         int rtval;
 679         struct vnode *vp;
 680         int bytes = count * PAGE_SIZE;
 681
 682         vp = object->handle;
 683         VM_OBJECT_WUNLOCK(object);
 684         rtval = VOP_GETPAGES(vp, m, bytes, reqpage);
 685         KASSERT(rtval != EOPNOTSUPP,
 686             ("vnode_pager: FS getpages not implemented\n"));
 687         VM_OBJECT_WLOCK(object);
 688         return rtval;
 689 }
 690
 691 static int
 692 vnode_pager_getpages_async(vm_object_t object, vm_page_t *m, int count,
 693     int reqpage, vop_getpages_iodone_t iodone, void *arg)
 694 {
 695         struct vnode *vp;
 696         int rtval;
 697
 698         vp = object->handle;
 699         VM_OBJECT_WUNLOCK(object);
 700         rtval = VOP_GETPAGES_ASYNC(vp, m, count * PAGE_SIZE, reqpage,
 701             iodone, arg);
 702         KASSERT(rtval != EOPNOTSUPP,
 703             ("vnode_pager: FS getpages_async not implemented\n"));
 704         VM_OBJECT_WLOCK(object);
 705         return (rtval);
 706 }
 707
 708 /*
 709  * The implementation of VOP_GETPAGES() and VOP_GETPAGES_ASYNC() for
 710  * local filesystems, where partially valid pages can only occur at
 711  * the end of file.
 712  */
 713 int
 714 vnode_pager_local_getpages(struct vop_getpages_args *ap)
 715 {
 716
 717         return (vnode_pager_local_getpages0(ap->a_vp, ap->a_m, ap->a_count,
 718             ap->a_reqpage, NULL, NULL));
 719 }
 720
 721 int
 722 vnode_pager_local_getpages_async(struct vop_getpages_async_args *ap)
 723 {
 724
 725         return (vnode_pager_local_getpages0(ap->a_vp, ap->a_m, ap->a_count,
 726             ap->a_reqpage, ap->a_iodone, ap->a_arg));
 727 }
 728
 729 static int
 730 vnode_pager_local_getpages0(struct vnode *vp, vm_page_t *m, int bytecount,
 731     int reqpage, vop_getpages_iodone_t iodone, void *arg)
 732 {
 733         vm_page_t mreq;
 734
 735         mreq = m[reqpage];
 736
 737         /*
 738          * Since the caller has busied the requested page, that page's valid
 739          * field will not be changed by other threads.
 740          */
 741         vm_page_assert_xbusied(mreq);
 742
 743         /*
 744          * The requested page has valid blocks.  Invalid part can only
 745          * exist at the end of file, and the page is made fully valid
 746          * by zeroing in vm_pager_get_pages().  Free non-requested
 747          * pages, since no i/o is done to read its content.
 748          */
 749         if (mreq->valid != 0) {
 750                 vm_pager_free_nonreq(mreq->object, m, reqpage,
 751                     round_page(bytecount) / PAGE_SIZE, FALSE);
 752                 if (iodone != NULL)
 753                         iodone(arg, m, reqpage, 0);
 754                 return (VM_PAGER_OK);
 755         }
 756
 757         return (vnode_pager_generic_getpages(vp, m, bytecount, reqpage,
 758             iodone, arg));
 759 }
 760
 761 /*
 762  * This is now called from local media FS's to operate against their
 763  * own vnodes if they fail to implement VOP_GETPAGES.
 764  */
 765 int
 766 vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int bytecount,
 767     int reqpage, vop_getpages_iodone_t iodone, void *arg)
 768 {
 769         vm_object_t object;
 770         struct bufobj *bo;
 771         struct buf *bp;
 772         daddr_t firstaddr, reqblock;
 773         off_t foff, pib;
 774         int pbefore, pafter, i, size, bsize, first, last, *freecnt;
 775         int count, error, before, after, secmask;
 776
 777         KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
 778             ("vnode_pager_generic_getpages does not support devices"));
 779         if (vp->v_iflag & VI_DOOMED)
 780                 return (VM_PAGER_BAD);
 781
 782         object = vp->v_object;
 783         count = bytecount / PAGE_SIZE;
 784         bsize = vp->v_mount->mnt_stat.f_iosize;
 785
 786         /*
 787          * Synchronous and asynchronous paging operations use different
 788          * free pbuf counters.  This is done to avoid asynchronous requests
 789          * to consume all pbufs.
 790          * Allocate the pbuf at the very beginning of the function, so that
 791          * if we are low on certain kind of pbufs don't even proceed to BMAP,
 792          * but sleep.
 793          */
 794         freecnt = iodone != NULL ?
 795             &vnode_async_pbuf_freecnt : &vnode_pbuf_freecnt;
 796         bp = getpbuf(freecnt);
 797
 798         /*
 799          * Get the underlying device blocks for the file with VOP_BMAP().
 800          * If the file system doesn't support VOP_BMAP, use old way of
 801          * getting pages via VOP_READ.
 802          */
 803         error = VOP_BMAP(vp, IDX_TO_OFF(m[reqpage]->pindex) / bsize, &bo,
 804             &reqblock, &after, &before);
 805         if (error == EOPNOTSUPP) {
 806                 relpbuf(bp, freecnt);
 807                 VM_OBJECT_WLOCK(object);
 808                 for (i = 0; i < count; i++)
 809                         if (i != reqpage) {
 810                                 vm_page_lock(m[i]);
 811                                 vm_page_free(m[i]);
 812                                 vm_page_unlock(m[i]);
 813                         }
 814                 PCPU_INC(cnt.v_vnodein);
 815                 PCPU_INC(cnt.v_vnodepgsin);
 816                 error = vnode_pager_input_old(object, m[reqpage]);
 817                 VM_OBJECT_WUNLOCK(object);
 818                 return (error);
 819         } else if (error != 0) {
 820                 relpbuf(bp, freecnt);
 821                 vm_pager_free_nonreq(object, m, reqpage, count, FALSE);
 822                 return (VM_PAGER_ERROR);
 823
 824                 /*
 825                  * If the blocksize is smaller than a page size, then use
 826                  * special small filesystem code.
 827                  */
 828         } else if ((PAGE_SIZE / bsize) > 1) {
 829                 relpbuf(bp, freecnt);
 830                 vm_pager_free_nonreq(object, m, reqpage, count, FALSE);
 831                 PCPU_INC(cnt.v_vnodein);
 832                 PCPU_INC(cnt.v_vnodepgsin);
 833                 return (vnode_pager_input_smlfs(object, m[reqpage]));
 834         }
 835
 836         /*
 837          * Since the caller has busied the requested page, that page's valid
 838          * field will not be changed by other threads.
 839          */
 840         vm_page_assert_xbusied(m[reqpage]);
 841
 842         /*
 843          * If we have a completely valid page available to us, we can
 844          * clean up and return.  Otherwise we have to re-read the
 845          * media.
 846          */
 847         if (m[reqpage]->valid == VM_PAGE_BITS_ALL) {
 848                 relpbuf(bp, freecnt);
 849                 vm_pager_free_nonreq(object, m, reqpage, count, FALSE);
 850                 return (VM_PAGER_OK);
 851         } else if (reqblock == -1) {
 852                 relpbuf(bp, freecnt);
 853                 pmap_zero_page(m[reqpage]);
 854                 KASSERT(m[reqpage]->dirty == 0,
 855                     ("vnode_pager_generic_getpages: page %p is dirty", m));
 856                 VM_OBJECT_WLOCK(object);
 857                 m[reqpage]->valid = VM_PAGE_BITS_ALL;
 858                 vm_pager_free_nonreq(object, m, reqpage, count, TRUE);
 859                 VM_OBJECT_WUNLOCK(object);
 860                 return (VM_PAGER_OK);
 861         } else if (m[reqpage]->valid != 0) {
 862                 VM_OBJECT_WLOCK(object);
 863                 m[reqpage]->valid = 0;
 864                 VM_OBJECT_WUNLOCK(object);
 865         }
 866
 867         pib = IDX_TO_OFF(m[reqpage]->pindex) % bsize;
 868         pbefore = ((daddr_t)before * bsize + pib) / PAGE_SIZE;
 869         pafter = ((daddr_t)(after + 1) * bsize - pib) / PAGE_SIZE - 1;
 870         first = reqpage < pbefore ? 0 : reqpage - pbefore;
 871         last = reqpage + pafter >= count ? count - 1 : reqpage + pafter;
 872         if (first > 0 || last + 1 < count) {
 873                 VM_OBJECT_WLOCK(object);
 874                 for (i = 0; i < first; i++) {
 875                         vm_page_lock(m[i]);
 876                         vm_page_free(m[i]);
 877                         vm_page_unlock(m[i]);
 878                 }
 879                 for (i = last + 1; i < count; i++) {
 880                         vm_page_lock(m[i]);
 881                         vm_page_free(m[i]);
 882                         vm_page_unlock(m[i]);
 883                 }
 884                 VM_OBJECT_WUNLOCK(object);
 885         }
 886
 887         /*
 888          * here on direct device I/O
 889          */
 890         firstaddr = reqblock;
 891         firstaddr += pib / DEV_BSIZE;
 892         firstaddr -= IDX_TO_OFF(reqpage - first) / DEV_BSIZE;
 893
 894         /*
 895          * The first and last page have been calculated now, move
 896          * input pages to be zero based, and adjust the count.
 897          */
 898         m += first;
 899         reqpage -= first;
 900         count = last - first + 1;
 901
 902         /*
 903          * calculate the file virtual address for the transfer
 904          */
 905         foff = IDX_TO_OFF(m[0]->pindex);
 906
 907         /*
 908          * calculate the size of the transfer
 909          */
 910         size = count * PAGE_SIZE;
 911         KASSERT(count > 0, ("zero count"));
 912         if ((foff + size) > object->un_pager.vnp.vnp_size)
 913                 size = object->un_pager.vnp.vnp_size - foff;
 914         KASSERT(size > 0, ("zero size"));
 915
 916         /*
 917          * round up physical size for real devices.
 918          */
 919         secmask = bo->bo_bsize - 1;
 920         KASSERT(secmask < PAGE_SIZE && secmask > 0,
 921             ("vnode_pager_generic_getpages: sector size %d too large",
 922             secmask + 1));
 923         size = (size + secmask) & ~secmask;
 924
 925         /*
 926          * and map the pages to be read into the kva, if the filesystem
 927          * requires mapped buffers.
 928          */
 929         if ((vp->v_mount->mnt_kern_flag & MNTK_UNMAPPED_BUFS) != 0 &&
 930             unmapped_buf_allowed) {
 931                 bp->b_data = unmapped_buf;
 932                 bp->b_offset = 0;
 933         } else {
 934                 bp->b_data = bp->b_kvabase;
 935                 pmap_qenter((vm_offset_t)bp->b_data, m, count);
 936         }
 937
 938         /* build a minimal buffer header */
 939         bp->b_iocmd = BIO_READ;
 940         KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
 941         KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
 942         bp->b_rcred = crhold(curthread->td_ucred);
 943         bp->b_wcred = crhold(curthread->td_ucred);
 944         bp->b_blkno = firstaddr;
 945         pbgetbo(bo, bp);
 946         bp->b_vp = vp;
 947         bp->b_bcount = size;
 948         bp->b_bufsize = size;
 949         bp->b_runningbufspace = bp->b_bufsize;
 950         for (i = 0; i < count; i++)
 951                 bp->b_pages[i] = m[i];
 952         bp->b_npages = count;
 953         bp->b_pager.pg_reqpage = reqpage;
 954         atomic_add_long(&runningbufspace, bp->b_runningbufspace);
 955
 956         PCPU_INC(cnt.v_vnodein);
 957         PCPU_ADD(cnt.v_vnodepgsin, count);
 958
 959         /* do the input */
 960         bp->b_iooffset = dbtob(bp->b_blkno);
 961
 962         if (iodone != NULL) { /* async */
 963                 bp->b_pager.pg_iodone = iodone;
 964                 bp->b_caller1 = arg;
 965                 bp->b_iodone = vnode_pager_generic_getpages_done_async;
 966                 bp->b_flags |= B_ASYNC;
 967                 BUF_KERNPROC(bp);
 968                 bstrategy(bp);
 969                 /* Good bye! */
 970         } else {
 971                 bp->b_iodone = bdone;
 972                 bstrategy(bp);
 973                 bwait(bp, PVM, "vnread");
 974                 error = vnode_pager_generic_getpages_done(bp);
 975                 for (i = 0; i < bp->b_npages; i++)
 976                         bp->b_pages[i] = NULL;
 977                 bp->b_vp = NULL;
 978                 pbrelbo(bp);
 979                 relpbuf(bp, &vnode_pbuf_freecnt);
 980         }
 981
 982         return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
 983 }
 984
 985 static void
 986 vnode_pager_generic_getpages_done_async(struct buf *bp)
 987 {
 988         int error;
 989
 990         error = vnode_pager_generic_getpages_done(bp);
 991         bp->b_pager.pg_iodone(bp->b_caller1, bp->b_pages,
 992           bp->b_pager.pg_reqpage, error);
 993         for (int i = 0; i < bp->b_npages; i++)
 994                 bp->b_pages[i] = NULL;
 995         bp->b_vp = NULL;
 996         pbrelbo(bp);
 997         relpbuf(bp, &vnode_async_pbuf_freecnt);
 998 }
 999
1000 static int
1001 vnode_pager_generic_getpages_done(struct buf *bp)
1002 {
1003         vm_object_t object;
1004         off_t tfoff, nextoff;
1005         int i, error;
1006
1007         error = (bp->b_ioflags & BIO_ERROR) != 0 ? EIO : 0;
1008         object = bp->b_vp->v_object;
1009
1010         if (error == 0 && bp->b_bcount != bp->b_npages * PAGE_SIZE) {
1011                 if (!buf_mapped(bp)) {
1012                         bp->b_data = bp->b_kvabase;
1013                         pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages,
1014                             bp->b_npages);
1015                 }
1016                 bzero(bp->b_data + bp->b_bcount,
1017                     PAGE_SIZE * bp->b_npages - bp->b_bcount);
1018         }
1019         if (buf_mapped(bp)) {
1020                 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages);
1021                 bp->b_data = unmapped_buf;
1022         }
1023
1024         VM_OBJECT_WLOCK(object);
1025         for (i = 0, tfoff = IDX_TO_OFF(bp->b_pages[0]->pindex);
1026             i < bp->b_npages; i++, tfoff = nextoff) {
1027                 vm_page_t mt;
1028
1029                 nextoff = tfoff + PAGE_SIZE;
1030                 mt = bp->b_pages[i];
1031
1032                 if (nextoff <= object->un_pager.vnp.vnp_size) {
1033                         /*
1034                          * Read filled up entire page.
1035                          */
1036                         mt->valid = VM_PAGE_BITS_ALL;
1037                         KASSERT(mt->dirty == 0,
1038                             ("%s: page %p is dirty", __func__, mt));
1039                         KASSERT(!pmap_page_is_mapped(mt),
1040                             ("%s: page %p is mapped", __func__, mt));
1041                 } else {
1042                         /*
1043                          * Read did not fill up entire page.
1044                          *
1045                          * Currently we do not set the entire page valid,
1046                          * we just try to clear the piece that we couldn't
1047                          * read.
1048                          */
1049                         vm_page_set_valid_range(mt, 0,
1050                             object->un_pager.vnp.vnp_size - tfoff);
1051                         KASSERT((mt->dirty & vm_page_bits(0,
1052                             object->un_pager.vnp.vnp_size - tfoff)) == 0,
1053                             ("%s: page %p is dirty", __func__, mt));
1054                 }
1055
1056                 if (i != bp->b_pager.pg_reqpage)
1057                         vm_page_readahead_finish(mt);
1058         }
1059         VM_OBJECT_WUNLOCK(object);
1060         if (error != 0)
1061                 printf("%s: I/O read error %d\n", __func__, error);
1062
1063         return (error);
1064 }
1065
1066 /*
1067  * EOPNOTSUPP is no longer legal.  For local media VFS's that do not
1068  * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to
1069  * vnode_pager_generic_putpages() to implement the previous behaviour.
1070  *
1071  * All other FS's should use the bypass to get to the local media
1072  * backing vp's VOP_PUTPAGES.
1073  */
1074 static void
1075 vnode_pager_putpages(vm_object_t object, vm_page_t *m, int count,
1076     int flags, int *rtvals)
1077 {
1078         int rtval;
1079         struct vnode *vp;
1080         int bytes = count * PAGE_SIZE;
1081
1082         /*
1083          * Force synchronous operation if we are extremely low on memory
1084          * to prevent a low-memory deadlock.  VOP operations often need to
1085          * allocate more memory to initiate the I/O ( i.e. do a BMAP
1086          * operation ).  The swapper handles the case by limiting the amount
1087          * of asynchronous I/O, but that sort of solution doesn't scale well
1088          * for the vnode pager without a lot of work.
1089          *
1090          * Also, the backing vnode's iodone routine may not wake the pageout
1091          * daemon up.  This should be probably be addressed XXX.
1092          */
1093
1094         if (vm_cnt.v_free_count + vm_cnt.v_cache_count <
1095             vm_cnt.v_pageout_free_min)
1096                 flags |= VM_PAGER_PUT_SYNC;
1097
1098         /*
1099          * Call device-specific putpages function
1100          */
1101         vp = object->handle;
1102         VM_OBJECT_WUNLOCK(object);
1103         rtval = VOP_PUTPAGES(vp, m, bytes, flags, rtvals);
1104         KASSERT(rtval != EOPNOTSUPP,
1105             ("vnode_pager: stale FS putpages\n"));
1106         VM_OBJECT_WLOCK(object);
1107 }
1108
1109
1110 /*
1111  * This is now called from local media FS's to operate against their
1112  * own vnodes if they fail to implement VOP_PUTPAGES.
1113  *
1114  * This is typically called indirectly via the pageout daemon and
1115  * clustering has already typically occured, so in general we ask the
1116  * underlying filesystem to write the data out asynchronously rather
1117  * then delayed.
1118  */
1119 int
1120 vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *ma, int bytecount,
1121     int flags, int *rtvals)
1122 {
1123         int i;
1124         vm_object_t object;
1125         vm_page_t m;
1126         int count;
1127
1128         int maxsize, ncount;
1129         vm_ooffset_t poffset;
1130         struct uio auio;
1131         struct iovec aiov;
1132         int error;
1133         int ioflags;
1134         int ppscheck = 0;
1135         static struct timeval lastfail;
1136         static int curfail;
1137
1138         object = vp->v_object;
1139         count = bytecount / PAGE_SIZE;
1140
1141         for (i = 0; i < count; i++)
1142                 rtvals[i] = VM_PAGER_ERROR;
1143
1144         if ((int64_t)ma[0]->pindex < 0) {
1145                 printf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%lx(%lx)\n",
1146                     (long)ma[0]->pindex, (u_long)ma[0]->dirty);
1147                 rtvals[0] = VM_PAGER_BAD;
1148                 return VM_PAGER_BAD;
1149         }
1150
1151         maxsize = count * PAGE_SIZE;
1152         ncount = count;
1153
1154         poffset = IDX_TO_OFF(ma[0]->pindex);
1155
1156         /*
1157          * If the page-aligned write is larger then the actual file we
1158          * have to invalidate pages occuring beyond the file EOF.  However,
1159          * there is an edge case where a file may not be page-aligned where
1160          * the last page is partially invalid.  In this case the filesystem
1161          * may not properly clear the dirty bits for the entire page (which
1162          * could be VM_PAGE_BITS_ALL due to the page having been mmap()d).
1163          * With the page locked we are free to fix-up the dirty bits here.
1164          *
1165          * We do not under any circumstances truncate the valid bits, as
1166          * this will screw up bogus page replacement.
1167          */
1168         VM_OBJECT_WLOCK(object);
1169         if (maxsize + poffset > object->un_pager.vnp.vnp_size) {
1170                 if (object->un_pager.vnp.vnp_size > poffset) {
1171                         int pgoff;
1172
1173                         maxsize = object->un_pager.vnp.vnp_size - poffset;
1174                         ncount = btoc(maxsize);
1175                         if ((pgoff = (int)maxsize & PAGE_MASK) != 0) {
1176                                 /*
1177                                  * If the object is locked and the following
1178                                  * conditions hold, then the page's dirty
1179                                  * field cannot be concurrently changed by a
1180                                  * pmap operation.
1181                                  */
1182                                 m = ma[ncount - 1];
1183                                 vm_page_assert_sbusied(m);
1184                                 KASSERT(!pmap_page_is_write_mapped(m),
1185                 ("vnode_pager_generic_putpages: page %p is not read-only", m));
1186                                 vm_page_clear_dirty(m, pgoff, PAGE_SIZE -
1187                                     pgoff);
1188                         }
1189                 } else {
1190                         maxsize = 0;
1191                         ncount = 0;
1192                 }
1193                 if (ncount < count) {
1194                         for (i = ncount; i < count; i++) {
1195                                 rtvals[i] = VM_PAGER_BAD;
1196                         }
1197                 }
1198         }
1199         VM_OBJECT_WUNLOCK(object);
1200
1201         /*
1202          * pageouts are already clustered, use IO_ASYNC to force a bawrite()
1203          * rather then a bdwrite() to prevent paging I/O from saturating
1204          * the buffer cache.  Dummy-up the sequential heuristic to cause
1205          * large ranges to cluster.  If neither IO_SYNC or IO_ASYNC is set,
1206          * the system decides how to cluster.
1207          */
1208         ioflags = IO_VMIO;
1209         if (flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL))
1210                 ioflags |= IO_SYNC;
1211         else if ((flags & VM_PAGER_CLUSTER_OK) == 0)
1212                 ioflags |= IO_ASYNC;
1213         ioflags |= (flags & VM_PAGER_PUT_INVAL) ? IO_INVAL: 0;
1214         ioflags |= IO_SEQMAX << IO_SEQSHIFT;
1215
1216         aiov.iov_base = (caddr_t) 0;
1217         aiov.iov_len = maxsize;
1218         auio.uio_iov = &aiov;
1219         auio.uio_iovcnt = 1;
1220         auio.uio_offset = poffset;
1221         auio.uio_segflg = UIO_NOCOPY;
1222         auio.uio_rw = UIO_WRITE;
1223         auio.uio_resid = maxsize;
1224         auio.uio_td = (struct thread *) 0;
1225         error = VOP_WRITE(vp, &auio, ioflags, curthread->td_ucred);
1226         PCPU_INC(cnt.v_vnodeout);
1227         PCPU_ADD(cnt.v_vnodepgsout, ncount);
1228
1229         if (error) {
1230                 if ((ppscheck = ppsratecheck(&lastfail, &curfail, 1)))
1231                         printf("vnode_pager_putpages: I/O error %d\n", error);
1232         }
1233         if (auio.uio_resid) {
1234                 if (ppscheck || ppsratecheck(&lastfail, &curfail, 1))
1235                         printf("vnode_pager_putpages: residual I/O %zd at %lu\n",
1236                             auio.uio_resid, (u_long)ma[0]->pindex);
1237         }
1238         for (i = 0; i < ncount; i++) {
1239                 rtvals[i] = VM_PAGER_OK;
1240         }
1241         return rtvals[0];
1242 }
1243
1244 void
1245 vnode_pager_undirty_pages(vm_page_t *ma, int *rtvals, int written)
1246 {
1247         vm_object_t obj;
1248         int i, pos;
1249
1250         if (written == 0)
1251                 return;
1252         obj = ma[0]->object;
1253         VM_OBJECT_WLOCK(obj);
1254         for (i = 0, pos = 0; pos < written; i++, pos += PAGE_SIZE) {
1255                 if (pos < trunc_page(written)) {
1256                         rtvals[i] = VM_PAGER_OK;
1257                         vm_page_undirty(ma[i]);
1258                 } else {
1259                         /* Partially written page. */
1260                         rtvals[i] = VM_PAGER_AGAIN;
1261                         vm_page_clear_dirty(ma[i], 0, written & PAGE_MASK);
1262                 }
1263         }
1264         VM_OBJECT_WUNLOCK(obj);
1265 }
1266
1267 void
1268 vnode_pager_update_writecount(vm_object_t object, vm_offset_t start,
1269     vm_offset_t end)
1270 {
1271         struct vnode *vp;
1272         vm_ooffset_t old_wm;
1273
1274         VM_OBJECT_WLOCK(object);
1275         if (object->type != OBJT_VNODE) {
1276                 VM_OBJECT_WUNLOCK(object);
1277                 return;
1278         }
1279         old_wm = object->un_pager.vnp.writemappings;
1280         object->un_pager.vnp.writemappings += (vm_ooffset_t)end - start;
1281         vp = object->handle;
1282         if (old_wm == 0 && object->un_pager.vnp.writemappings != 0) {
1283                 ASSERT_VOP_ELOCKED(vp, "v_writecount inc");
1284                 VOP_ADD_WRITECOUNT(vp, 1);
1285                 CTR3(KTR_VFS, "%s: vp %p v_writecount increased to %d",
1286                     __func__, vp, vp->v_writecount);
1287         } else if (old_wm != 0 && object->un_pager.vnp.writemappings == 0) {
1288                 ASSERT_VOP_ELOCKED(vp, "v_writecount dec");
1289                 VOP_ADD_WRITECOUNT(vp, -1);
1290                 CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
1291                     __func__, vp, vp->v_writecount);
1292         }
1293         VM_OBJECT_WUNLOCK(object);
1294 }
1295
1296 void
1297 vnode_pager_release_writecount(vm_object_t object, vm_offset_t start,
1298     vm_offset_t end)
1299 {
1300         struct vnode *vp;
1301         struct mount *mp;
1302         vm_offset_t inc;
1303
1304         VM_OBJECT_WLOCK(object);
1305
1306         /*
1307          * First, recheck the object type to account for the race when
1308          * the vnode is reclaimed.
1309          */
1310         if (object->type != OBJT_VNODE) {
1311                 VM_OBJECT_WUNLOCK(object);
1312                 return;
1313         }
1314
1315         /*
1316          * Optimize for the case when writemappings is not going to
1317          * zero.
1318          */
1319         inc = end - start;
1320         if (object->un_pager.vnp.writemappings != inc) {
1321                 object->un_pager.vnp.writemappings -= inc;
1322                 VM_OBJECT_WUNLOCK(object);
1323                 return;
1324         }
1325
1326         vp = object->handle;
1327         vhold(vp);
1328         VM_OBJECT_WUNLOCK(object);
1329         mp = NULL;
1330         vn_start_write(vp, &mp, V_WAIT);
1331         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
1332
1333         /*
1334          * Decrement the object's writemappings, by swapping the start
1335          * and end arguments for vnode_pager_update_writecount().  If
1336          * there was not a race with vnode reclaimation, then the
1337          * vnode's v_writecount is decremented.
1338          */
1339         vnode_pager_update_writecount(object, end, start);
1340         VOP_UNLOCK(vp, 0);
1341         vdrop(vp);
1342         if (mp != NULL)
1343                 vn_finished_write(mp);
1344 }