The Design and Implementation of the FreeBSD Operating System, Second Edition
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sys/vm/vnode_pager.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-4-Clause
    3  *
    4  * Copyright (c) 1990 University of Utah.
    5  * Copyright (c) 1991 The Regents of the University of California.
    6  * All rights reserved.
    7  * Copyright (c) 1993, 1994 John S. Dyson
    8  * Copyright (c) 1995, David Greenman
    9  *
   10  * This code is derived from software contributed to Berkeley by
   11  * the Systems Programming Group of the University of Utah Computer
   12  * Science Department.
   13  *
   14  * Redistribution and use in source and binary forms, with or without
   15  * modification, are permitted provided that the following conditions
   16  * are met:
   17  * 1. Redistributions of source code must retain the above copyright
   18  *    notice, this list of conditions and the following disclaimer.
   19  * 2. Redistributions in binary form must reproduce the above copyright
   20  *    notice, this list of conditions and the following disclaimer in the
   21  *    documentation and/or other materials provided with the distribution.
   22  * 3. All advertising materials mentioning features or use of this software
   23  *    must display the following acknowledgement:
   24  *      This product includes software developed by the University of
   25  *      California, Berkeley and its contributors.
   26  * 4. Neither the name of the University nor the names of its contributors
   27  *    may be used to endorse or promote products derived from this software
   28  *    without specific prior written permission.
   29  *
   30  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   31  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   32  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   33  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   34  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   35  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   36  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   37  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   38  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   39  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   40  * SUCH DAMAGE.
   41  *
   42  *      from: @(#)vnode_pager.c 7.5 (Berkeley) 4/20/91
   43  */
   44 
   45 /*
   46  * Page to/from files (vnodes).
   47  */
   48 
   49 /*
   50  * TODO:
   51  *      Implement VOP_GETPAGES/PUTPAGES interface for filesystems. Will
   52  *      greatly re-simplify the vnode_pager.
   53  */
   54 
   55 #include <sys/cdefs.h>
   56 __FBSDID("$FreeBSD: head/sys/vm/vnode_pager.c 331723 2018-03-29 02:54:50Z jeff $");
   57 
   58 #include "opt_vm.h"
   59 
   60 #include <sys/param.h>
   61 #include <sys/systm.h>
   62 #include <sys/sysctl.h>
   63 #include <sys/proc.h>
   64 #include <sys/vnode.h>
   65 #include <sys/mount.h>
   66 #include <sys/bio.h>
   67 #include <sys/buf.h>
   68 #include <sys/vmmeter.h>
   69 #include <sys/limits.h>
   70 #include <sys/conf.h>
   71 #include <sys/rwlock.h>
   72 #include <sys/sf_buf.h>
   73 #include <sys/domainset.h>
   74 
   75 #include <machine/atomic.h>
   76 
   77 #include <vm/vm.h>
   78 #include <vm/vm_param.h>
   79 #include <vm/vm_object.h>
   80 #include <vm/vm_page.h>
   81 #include <vm/vm_pager.h>
   82 #include <vm/vm_map.h>
   83 #include <vm/vnode_pager.h>
   84 #include <vm/vm_extern.h>
   85 
   86 static int vnode_pager_addr(struct vnode *vp, vm_ooffset_t address,
   87     daddr_t *rtaddress, int *run);
   88 static int vnode_pager_input_smlfs(vm_object_t object, vm_page_t m);
   89 static int vnode_pager_input_old(vm_object_t object, vm_page_t m);
   90 static void vnode_pager_dealloc(vm_object_t);
   91 static int vnode_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *);
   92 static int vnode_pager_getpages_async(vm_object_t, vm_page_t *, int, int *,
   93     int *, vop_getpages_iodone_t, void *);
   94 static void vnode_pager_putpages(vm_object_t, vm_page_t *, int, int, int *);
   95 static boolean_t vnode_pager_haspage(vm_object_t, vm_pindex_t, int *, int *);
   96 static vm_object_t vnode_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
   97     vm_ooffset_t, struct ucred *cred);
   98 static int vnode_pager_generic_getpages_done(struct buf *);
   99 static void vnode_pager_generic_getpages_done_async(struct buf *);
  100 
  101 struct pagerops vnodepagerops = {
  102         .pgo_alloc =    vnode_pager_alloc,
  103         .pgo_dealloc =  vnode_pager_dealloc,
  104         .pgo_getpages = vnode_pager_getpages,
  105         .pgo_getpages_async = vnode_pager_getpages_async,
  106         .pgo_putpages = vnode_pager_putpages,
  107         .pgo_haspage =  vnode_pager_haspage,
  108 };
  109 
  110 int vnode_pbuf_freecnt;
  111 int vnode_async_pbuf_freecnt;
  112 
  113 static struct domainset *vnode_domainset = NULL;
  114 
  115 SYSCTL_PROC(_debug, OID_AUTO, vnode_domainset, CTLTYPE_STRING | CTLFLAG_RW,
  116     &vnode_domainset, 0, sysctl_handle_domainset, "A",
  117     "Default vnode NUMA policy");
  118 
  119 /* Create the VM system backing object for this vnode */
  120 int
  121 vnode_create_vobject(struct vnode *vp, off_t isize, struct thread *td)
  122 {
  123         vm_object_t object;
  124         vm_ooffset_t size = isize;
  125         struct vattr va;
  126 
  127         if (!vn_isdisk(vp, NULL) && vn_canvmio(vp) == FALSE)
  128                 return (0);
  129 
  130         while ((object = vp->v_object) != NULL) {
  131                 VM_OBJECT_WLOCK(object);
  132                 if (!(object->flags & OBJ_DEAD)) {
  133                         VM_OBJECT_WUNLOCK(object);
  134                         return (0);
  135                 }
  136                 VOP_UNLOCK(vp, 0);
  137                 vm_object_set_flag(object, OBJ_DISCONNECTWNT);
  138                 VM_OBJECT_SLEEP(object, object, PDROP | PVM, "vodead", 0);
  139                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
  140         }
  141 
  142         if (size == 0) {
  143                 if (vn_isdisk(vp, NULL)) {
  144                         size = IDX_TO_OFF(INT_MAX);
  145                 } else {
  146                         if (VOP_GETATTR(vp, &va, td->td_ucred))
  147                                 return (0);
  148                         size = va.va_size;
  149                 }
  150         }
  151 
  152         object = vnode_pager_alloc(vp, size, 0, 0, td->td_ucred);
  153         /*
  154          * Dereference the reference we just created.  This assumes
  155          * that the object is associated with the vp.
  156          */
  157         VM_OBJECT_WLOCK(object);
  158         object->ref_count--;
  159         VM_OBJECT_WUNLOCK(object);
  160         vrele(vp);
  161 
  162         KASSERT(vp->v_object != NULL, ("vnode_create_vobject: NULL object"));
  163 
  164         return (0);
  165 }
  166 
  167 void
  168 vnode_destroy_vobject(struct vnode *vp)
  169 {
  170         struct vm_object *obj;
  171 
  172         obj = vp->v_object;
  173         if (obj == NULL)
  174                 return;
  175         ASSERT_VOP_ELOCKED(vp, "vnode_destroy_vobject");
  176         VM_OBJECT_WLOCK(obj);
  177         umtx_shm_object_terminated(obj);
  178         if (obj->ref_count == 0) {
  179                 /*
  180                  * don't double-terminate the object
  181                  */
  182                 if ((obj->flags & OBJ_DEAD) == 0) {
  183                         vm_object_terminate(obj);
  184                 } else {
  185                         /*
  186                          * Waiters were already handled during object
  187                          * termination.  The exclusive vnode lock hopefully
  188                          * prevented new waiters from referencing the dying
  189                          * object.
  190                          */
  191                         KASSERT((obj->flags & OBJ_DISCONNECTWNT) == 0,
  192                             ("OBJ_DISCONNECTWNT set obj %p flags %x",
  193                             obj, obj->flags));
  194                         vp->v_object = NULL;
  195                         VM_OBJECT_WUNLOCK(obj);
  196                 }
  197         } else {
  198                 /*
  199                  * Woe to the process that tries to page now :-).
  200                  */
  201                 vm_pager_deallocate(obj);
  202                 VM_OBJECT_WUNLOCK(obj);
  203         }
  204         KASSERT(vp->v_object == NULL, ("vp %p obj %p", vp, vp->v_object));
  205 }
  206 
  207 
  208 /*
  209  * Allocate (or lookup) pager for a vnode.
  210  * Handle is a vnode pointer.
  211  *
  212  * MPSAFE
  213  */
  214 vm_object_t
  215 vnode_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
  216     vm_ooffset_t offset, struct ucred *cred)
  217 {
  218         vm_object_t object;
  219         struct vnode *vp;
  220 
  221         /*
  222          * Pageout to vnode, no can do yet.
  223          */
  224         if (handle == NULL)
  225                 return (NULL);
  226 
  227         vp = (struct vnode *) handle;
  228 
  229         /*
  230          * If the object is being terminated, wait for it to
  231          * go away.
  232          */
  233 retry:
  234         while ((object = vp->v_object) != NULL) {
  235                 VM_OBJECT_WLOCK(object);
  236                 if ((object->flags & OBJ_DEAD) == 0)
  237                         break;
  238                 vm_object_set_flag(object, OBJ_DISCONNECTWNT);
  239                 VM_OBJECT_SLEEP(object, object, PDROP | PVM, "vadead", 0);
  240         }
  241 
  242         KASSERT(vp->v_usecount != 0, ("vnode_pager_alloc: no vnode reference"));
  243 
  244         if (object == NULL) {
  245                 /*
  246                  * Add an object of the appropriate size
  247                  */
  248                 object = vm_object_allocate(OBJT_VNODE, OFF_TO_IDX(round_page(size)));
  249 
  250                 object->un_pager.vnp.vnp_size = size;
  251                 object->un_pager.vnp.writemappings = 0;
  252                 object->domain.dr_policy = vnode_domainset;
  253 
  254                 object->handle = handle;
  255                 VI_LOCK(vp);
  256                 if (vp->v_object != NULL) {
  257                         /*
  258                          * Object has been created while we were sleeping
  259                          */
  260                         VI_UNLOCK(vp);
  261                         VM_OBJECT_WLOCK(object);
  262                         KASSERT(object->ref_count == 1,
  263                             ("leaked ref %p %d", object, object->ref_count));
  264                         object->type = OBJT_DEAD;
  265                         object->ref_count = 0;
  266                         VM_OBJECT_WUNLOCK(object);
  267                         vm_object_destroy(object);
  268                         goto retry;
  269                 }
  270                 vp->v_object = object;
  271                 VI_UNLOCK(vp);
  272         } else {
  273                 object->ref_count++;
  274 #if VM_NRESERVLEVEL > 0
  275                 vm_object_color(object, 0);
  276 #endif
  277                 VM_OBJECT_WUNLOCK(object);
  278         }
  279         vrefact(vp);
  280         return (object);
  281 }
  282 
  283 /*
  284  *      The object must be locked.
  285  */
  286 static void
  287 vnode_pager_dealloc(vm_object_t object)
  288 {
  289         struct vnode *vp;
  290         int refs;
  291 
  292         vp = object->handle;
  293         if (vp == NULL)
  294                 panic("vnode_pager_dealloc: pager already dealloced");
  295 
  296         VM_OBJECT_ASSERT_WLOCKED(object);
  297         vm_object_pip_wait(object, "vnpdea");
  298         refs = object->ref_count;
  299 
  300         object->handle = NULL;
  301         object->type = OBJT_DEAD;
  302         if (object->flags & OBJ_DISCONNECTWNT) {
  303                 vm_object_clear_flag(object, OBJ_DISCONNECTWNT);
  304                 wakeup(object);
  305         }
  306         ASSERT_VOP_ELOCKED(vp, "vnode_pager_dealloc");
  307         if (object->un_pager.vnp.writemappings > 0) {
  308                 object->un_pager.vnp.writemappings = 0;
  309                 VOP_ADD_WRITECOUNT(vp, -1);
  310                 CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
  311                     __func__, vp, vp->v_writecount);
  312         }
  313         vp->v_object = NULL;
  314         VOP_UNSET_TEXT(vp);
  315         VM_OBJECT_WUNLOCK(object);
  316         while (refs-- > 0)
  317                 vunref(vp);
  318         VM_OBJECT_WLOCK(object);
  319 }
  320 
  321 static boolean_t
  322 vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
  323     int *after)
  324 {
  325         struct vnode *vp = object->handle;
  326         daddr_t bn;
  327         int err;
  328         daddr_t reqblock;
  329         int poff;
  330         int bsize;
  331         int pagesperblock, blocksperpage;
  332 
  333         VM_OBJECT_ASSERT_WLOCKED(object);
  334         /*
  335          * If no vp or vp is doomed or marked transparent to VM, we do not
  336          * have the page.
  337          */
  338         if (vp == NULL || vp->v_iflag & VI_DOOMED)
  339                 return FALSE;
  340         /*
  341          * If the offset is beyond end of file we do
  342          * not have the page.
  343          */
  344         if (IDX_TO_OFF(pindex) >= object->un_pager.vnp.vnp_size)
  345                 return FALSE;
  346 
  347         bsize = vp->v_mount->mnt_stat.f_iosize;
  348         pagesperblock = bsize / PAGE_SIZE;
  349         blocksperpage = 0;
  350         if (pagesperblock > 0) {
  351                 reqblock = pindex / pagesperblock;
  352         } else {
  353                 blocksperpage = (PAGE_SIZE / bsize);
  354                 reqblock = pindex * blocksperpage;
  355         }
  356         VM_OBJECT_WUNLOCK(object);
  357         err = VOP_BMAP(vp, reqblock, NULL, &bn, after, before);
  358         VM_OBJECT_WLOCK(object);
  359         if (err)
  360                 return TRUE;
  361         if (bn == -1)
  362                 return FALSE;
  363         if (pagesperblock > 0) {
  364                 poff = pindex - (reqblock * pagesperblock);
  365                 if (before) {
  366                         *before *= pagesperblock;
  367                         *before += poff;
  368                 }
  369                 if (after) {
  370                         /*
  371                          * The BMAP vop can report a partial block in the
  372                          * 'after', but must not report blocks after EOF.
  373                          * Assert the latter, and truncate 'after' in case
  374                          * of the former.
  375                          */
  376                         KASSERT((reqblock + *after) * pagesperblock <
  377                             roundup2(object->size, pagesperblock),
  378                             ("%s: reqblock %jd after %d size %ju", __func__,
  379                             (intmax_t )reqblock, *after,
  380                             (uintmax_t )object->size));
  381                         *after *= pagesperblock;
  382                         *after += pagesperblock - (poff + 1);
  383                         if (pindex + *after >= object->size)
  384                                 *after = object->size - 1 - pindex;
  385                 }
  386         } else {
  387                 if (before) {
  388                         *before /= blocksperpage;
  389                 }
  390 
  391                 if (after) {
  392                         *after /= blocksperpage;
  393                 }
  394         }
  395         return TRUE;
  396 }
  397 
  398 /*
  399  * Lets the VM system know about a change in size for a file.
  400  * We adjust our own internal size and flush any cached pages in
  401  * the associated object that are affected by the size change.
  402  *
  403  * Note: this routine may be invoked as a result of a pager put
  404  * operation (possibly at object termination time), so we must be careful.
  405  */
  406 void
  407 vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize)
  408 {
  409         vm_object_t object;
  410         vm_page_t m;
  411         vm_pindex_t nobjsize;
  412 
  413         if ((object = vp->v_object) == NULL)
  414                 return;
  415 /*      ASSERT_VOP_ELOCKED(vp, "vnode_pager_setsize and not locked vnode"); */
  416         VM_OBJECT_WLOCK(object);
  417         if (object->type == OBJT_DEAD) {
  418                 VM_OBJECT_WUNLOCK(object);
  419                 return;
  420         }
  421         KASSERT(object->type == OBJT_VNODE,
  422             ("not vnode-backed object %p", object));
  423         if (nsize == object->un_pager.vnp.vnp_size) {
  424                 /*
  425                  * Hasn't changed size
  426                  */
  427                 VM_OBJECT_WUNLOCK(object);
  428                 return;
  429         }
  430         nobjsize = OFF_TO_IDX(nsize + PAGE_MASK);
  431         if (nsize < object->un_pager.vnp.vnp_size) {
  432                 /*
  433                  * File has shrunk. Toss any cached pages beyond the new EOF.
  434                  */
  435                 if (nobjsize < object->size)
  436                         vm_object_page_remove(object, nobjsize, object->size,
  437                             0);
  438                 /*
  439                  * this gets rid of garbage at the end of a page that is now
  440                  * only partially backed by the vnode.
  441                  *
  442                  * XXX for some reason (I don't know yet), if we take a
  443                  * completely invalid page and mark it partially valid
  444                  * it can screw up NFS reads, so we don't allow the case.
  445                  */
  446                 if ((nsize & PAGE_MASK) &&
  447                     (m = vm_page_lookup(object, OFF_TO_IDX(nsize))) != NULL &&
  448                     m->valid != 0) {
  449                         int base = (int)nsize & PAGE_MASK;
  450                         int size = PAGE_SIZE - base;
  451 
  452                         /*
  453                          * Clear out partial-page garbage in case
  454                          * the page has been mapped.
  455                          */
  456                         pmap_zero_page_area(m, base, size);
  457 
  458                         /*
  459                          * Update the valid bits to reflect the blocks that
  460                          * have been zeroed.  Some of these valid bits may
  461                          * have already been set.
  462                          */
  463                         vm_page_set_valid_range(m, base, size);
  464 
  465                         /*
  466                          * Round "base" to the next block boundary so that the
  467                          * dirty bit for a partially zeroed block is not
  468                          * cleared.
  469                          */
  470                         base = roundup2(base, DEV_BSIZE);
  471 
  472                         /*
  473                          * Clear out partial-page dirty bits.
  474                          *
  475                          * note that we do not clear out the valid
  476                          * bits.  This would prevent bogus_page
  477                          * replacement from working properly.
  478                          */
  479                         vm_page_clear_dirty(m, base, PAGE_SIZE - base);
  480                 }
  481         }
  482         object->un_pager.vnp.vnp_size = nsize;
  483         object->size = nobjsize;
  484         VM_OBJECT_WUNLOCK(object);
  485 }
  486 
  487 /*
  488  * calculate the linear (byte) disk address of specified virtual
  489  * file address
  490  */
  491 static int
  492 vnode_pager_addr(struct vnode *vp, vm_ooffset_t address, daddr_t *rtaddress,
  493     int *run)
  494 {
  495         int bsize;
  496         int err;
  497         daddr_t vblock;
  498         daddr_t voffset;
  499 
  500         if (address < 0)
  501                 return -1;
  502 
  503         if (vp->v_iflag & VI_DOOMED)
  504                 return -1;
  505 
  506         bsize = vp->v_mount->mnt_stat.f_iosize;
  507         vblock = address / bsize;
  508         voffset = address % bsize;
  509 
  510         err = VOP_BMAP(vp, vblock, NULL, rtaddress, run, NULL);
  511         if (err == 0) {
  512                 if (*rtaddress != -1)
  513                         *rtaddress += voffset / DEV_BSIZE;
  514                 if (run) {
  515                         *run += 1;
  516                         *run *= bsize/PAGE_SIZE;
  517                         *run -= voffset/PAGE_SIZE;
  518                 }
  519         }
  520 
  521         return (err);
  522 }
  523 
  524 /*
  525  * small block filesystem vnode pager input
  526  */
  527 static int
  528 vnode_pager_input_smlfs(vm_object_t object, vm_page_t m)
  529 {
  530         struct vnode *vp;
  531         struct bufobj *bo;
  532         struct buf *bp;
  533         struct sf_buf *sf;
  534         daddr_t fileaddr;
  535         vm_offset_t bsize;
  536         vm_page_bits_t bits;
  537         int error, i;
  538 
  539         error = 0;
  540         vp = object->handle;
  541         if (vp->v_iflag & VI_DOOMED)
  542                 return VM_PAGER_BAD;
  543 
  544         bsize = vp->v_mount->mnt_stat.f_iosize;
  545 
  546         VOP_BMAP(vp, 0, &bo, 0, NULL, NULL);
  547 
  548         sf = sf_buf_alloc(m, 0);
  549 
  550         for (i = 0; i < PAGE_SIZE / bsize; i++) {
  551                 vm_ooffset_t address;
  552 
  553                 bits = vm_page_bits(i * bsize, bsize);
  554                 if (m->valid & bits)
  555                         continue;
  556 
  557                 address = IDX_TO_OFF(m->pindex) + i * bsize;
  558                 if (address >= object->un_pager.vnp.vnp_size) {
  559                         fileaddr = -1;
  560                 } else {
  561                         error = vnode_pager_addr(vp, address, &fileaddr, NULL);
  562                         if (error)
  563                                 break;
  564                 }
  565                 if (fileaddr != -1) {
  566                         bp = getpbuf(&vnode_pbuf_freecnt);
  567 
  568                         /* build a minimal buffer header */
  569                         bp->b_iocmd = BIO_READ;
  570                         bp->b_iodone = bdone;
  571                         KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
  572                         KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
  573                         bp->b_rcred = crhold(curthread->td_ucred);
  574                         bp->b_wcred = crhold(curthread->td_ucred);
  575                         bp->b_data = (caddr_t)sf_buf_kva(sf) + i * bsize;
  576                         bp->b_blkno = fileaddr;
  577                         pbgetbo(bo, bp);
  578                         bp->b_vp = vp;
  579                         bp->b_bcount = bsize;
  580                         bp->b_bufsize = bsize;
  581                         bp->b_runningbufspace = bp->b_bufsize;
  582                         atomic_add_long(&runningbufspace, bp->b_runningbufspace);
  583 
  584                         /* do the input */
  585                         bp->b_iooffset = dbtob(bp->b_blkno);
  586                         bstrategy(bp);
  587 
  588                         bwait(bp, PVM, "vnsrd");
  589 
  590                         if ((bp->b_ioflags & BIO_ERROR) != 0)
  591                                 error = EIO;
  592 
  593                         /*
  594                          * free the buffer header back to the swap buffer pool
  595                          */
  596                         bp->b_vp = NULL;
  597                         pbrelbo(bp);
  598                         relpbuf(bp, &vnode_pbuf_freecnt);
  599                         if (error)
  600                                 break;
  601                 } else
  602                         bzero((caddr_t)sf_buf_kva(sf) + i * bsize, bsize);
  603                 KASSERT((m->dirty & bits) == 0,
  604                     ("vnode_pager_input_smlfs: page %p is dirty", m));
  605                 VM_OBJECT_WLOCK(object);
  606                 m->valid |= bits;
  607                 VM_OBJECT_WUNLOCK(object);
  608         }
  609         sf_buf_free(sf);
  610         if (error) {
  611                 return VM_PAGER_ERROR;
  612         }
  613         return VM_PAGER_OK;
  614 }
  615 
  616 /*
  617  * old style vnode pager input routine
  618  */
  619 static int
  620 vnode_pager_input_old(vm_object_t object, vm_page_t m)
  621 {
  622         struct uio auio;
  623         struct iovec aiov;
  624         int error;
  625         int size;
  626         struct sf_buf *sf;
  627         struct vnode *vp;
  628 
  629         VM_OBJECT_ASSERT_WLOCKED(object);
  630         error = 0;
  631 
  632         /*
  633          * Return failure if beyond current EOF
  634          */
  635         if (IDX_TO_OFF(m->pindex) >= object->un_pager.vnp.vnp_size) {
  636                 return VM_PAGER_BAD;
  637         } else {
  638                 size = PAGE_SIZE;
  639                 if (IDX_TO_OFF(m->pindex) + size > object->un_pager.vnp.vnp_size)
  640                         size = object->un_pager.vnp.vnp_size - IDX_TO_OFF(m->pindex);
  641                 vp = object->handle;
  642                 VM_OBJECT_WUNLOCK(object);
  643 
  644                 /*
  645                  * Allocate a kernel virtual address and initialize so that
  646                  * we can use VOP_READ/WRITE routines.
  647                  */
  648                 sf = sf_buf_alloc(m, 0);
  649 
  650                 aiov.iov_base = (caddr_t)sf_buf_kva(sf);
  651                 aiov.iov_len = size;
  652                 auio.uio_iov = &aiov;
  653                 auio.uio_iovcnt = 1;
  654                 auio.uio_offset = IDX_TO_OFF(m->pindex);
  655                 auio.uio_segflg = UIO_SYSSPACE;
  656                 auio.uio_rw = UIO_READ;
  657                 auio.uio_resid = size;
  658                 auio.uio_td = curthread;
  659 
  660                 error = VOP_READ(vp, &auio, 0, curthread->td_ucred);
  661                 if (!error) {
  662                         int count = size - auio.uio_resid;
  663 
  664                         if (count == 0)
  665                                 error = EINVAL;
  666                         else if (count != PAGE_SIZE)
  667                                 bzero((caddr_t)sf_buf_kva(sf) + count,
  668                                     PAGE_SIZE - count);
  669                 }
  670                 sf_buf_free(sf);
  671 
  672                 VM_OBJECT_WLOCK(object);
  673         }
  674         KASSERT(m->dirty == 0, ("vnode_pager_input_old: page %p is dirty", m));
  675         if (!error)
  676                 m->valid = VM_PAGE_BITS_ALL;
  677         return error ? VM_PAGER_ERROR : VM_PAGER_OK;
  678 }
  679 
  680 /*
  681  * generic vnode pager input routine
  682  */
  683 
  684 /*
  685  * Local media VFS's that do not implement their own VOP_GETPAGES
  686  * should have their VOP_GETPAGES call to vnode_pager_generic_getpages()
  687  * to implement the previous behaviour.
  688  *
  689  * All other FS's should use the bypass to get to the local media
  690  * backing vp's VOP_GETPAGES.
  691  */
  692 static int
  693 vnode_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
  694     int *rahead)
  695 {
  696         struct vnode *vp;
  697         int rtval;
  698 
  699         vp = object->handle;
  700         VM_OBJECT_WUNLOCK(object);
  701         rtval = VOP_GETPAGES(vp, m, count, rbehind, rahead);
  702         KASSERT(rtval != EOPNOTSUPP,
  703             ("vnode_pager: FS getpages not implemented\n"));
  704         VM_OBJECT_WLOCK(object);
  705         return rtval;
  706 }
  707 
  708 static int
  709 vnode_pager_getpages_async(vm_object_t object, vm_page_t *m, int count,
  710     int *rbehind, int *rahead, vop_getpages_iodone_t iodone, void *arg)
  711 {
  712         struct vnode *vp;
  713         int rtval;
  714 
  715         vp = object->handle;
  716         VM_OBJECT_WUNLOCK(object);
  717         rtval = VOP_GETPAGES_ASYNC(vp, m, count, rbehind, rahead, iodone, arg);
  718         KASSERT(rtval != EOPNOTSUPP,
  719             ("vnode_pager: FS getpages_async not implemented\n"));
  720         VM_OBJECT_WLOCK(object);
  721         return (rtval);
  722 }
  723 
  724 /*
  725  * The implementation of VOP_GETPAGES() and VOP_GETPAGES_ASYNC() for
  726  * local filesystems, where partially valid pages can only occur at
  727  * the end of file.
  728  */
  729 int
  730 vnode_pager_local_getpages(struct vop_getpages_args *ap)
  731 {
  732 
  733         return (vnode_pager_generic_getpages(ap->a_vp, ap->a_m, ap->a_count,
  734             ap->a_rbehind, ap->a_rahead, NULL, NULL));
  735 }
  736 
  737 int
  738 vnode_pager_local_getpages_async(struct vop_getpages_async_args *ap)
  739 {
  740 
  741         return (vnode_pager_generic_getpages(ap->a_vp, ap->a_m, ap->a_count,
  742             ap->a_rbehind, ap->a_rahead, ap->a_iodone, ap->a_arg));
  743 }
  744 
  745 /*
  746  * This is now called from local media FS's to operate against their
  747  * own vnodes if they fail to implement VOP_GETPAGES.
  748  */
  749 int
  750 vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int count,
  751     int *a_rbehind, int *a_rahead, vop_getpages_iodone_t iodone, void *arg)
  752 {
  753         vm_object_t object;
  754         struct bufobj *bo;
  755         struct buf *bp;
  756         off_t foff;
  757 #ifdef INVARIANTS
  758         off_t blkno0;
  759 #endif
  760         int bsize, pagesperblock, *freecnt;
  761         int error, before, after, rbehind, rahead, poff, i;
  762         int bytecount, secmask;
  763 
  764         KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
  765             ("%s does not support devices", __func__));
  766 
  767         if (vp->v_iflag & VI_DOOMED)
  768                 return (VM_PAGER_BAD);
  769 
  770         object = vp->v_object;
  771         foff = IDX_TO_OFF(m[0]->pindex);
  772         bsize = vp->v_mount->mnt_stat.f_iosize;
  773         pagesperblock = bsize / PAGE_SIZE;
  774 
  775         KASSERT(foff < object->un_pager.vnp.vnp_size,
  776             ("%s: page %p offset beyond vp %p size", __func__, m[0], vp));
  777         KASSERT(count <= sizeof(bp->b_pages),
  778             ("%s: requested %d pages", __func__, count));
  779 
  780         /*
  781          * The last page has valid blocks.  Invalid part can only
  782          * exist at the end of file, and the page is made fully valid
  783          * by zeroing in vm_pager_get_pages().
  784          */
  785         if (m[count - 1]->valid != 0 && --count == 0) {
  786                 if (iodone != NULL)
  787                         iodone(arg, m, 1, 0);
  788                 return (VM_PAGER_OK);
  789         }
  790 
  791         /*
  792          * Synchronous and asynchronous paging operations use different
  793          * free pbuf counters.  This is done to avoid asynchronous requests
  794          * to consume all pbufs.
  795          * Allocate the pbuf at the very beginning of the function, so that
  796          * if we are low on certain kind of pbufs don't even proceed to BMAP,
  797          * but sleep.
  798          */
  799         freecnt = iodone != NULL ?
  800             &vnode_async_pbuf_freecnt : &vnode_pbuf_freecnt;
  801         bp = getpbuf(freecnt);
  802 
  803         /*
  804          * Get the underlying device blocks for the file with VOP_BMAP().
  805          * If the file system doesn't support VOP_BMAP, use old way of
  806          * getting pages via VOP_READ.
  807          */
  808         error = VOP_BMAP(vp, foff / bsize, &bo, &bp->b_blkno, &after, &before);
  809         if (error == EOPNOTSUPP) {
  810                 relpbuf(bp, freecnt);
  811                 VM_OBJECT_WLOCK(object);
  812                 for (i = 0; i < count; i++) {
  813                         VM_CNT_INC(v_vnodein);
  814                         VM_CNT_INC(v_vnodepgsin);
  815                         error = vnode_pager_input_old(object, m[i]);
  816                         if (error)
  817                                 break;
  818                 }
  819                 VM_OBJECT_WUNLOCK(object);
  820                 return (error);
  821         } else if (error != 0) {
  822                 relpbuf(bp, freecnt);
  823                 return (VM_PAGER_ERROR);
  824         }
  825 
  826         /*
  827          * If the file system supports BMAP, but blocksize is smaller
  828          * than a page size, then use special small filesystem code.
  829          */
  830         if (pagesperblock == 0) {
  831                 relpbuf(bp, freecnt);
  832                 for (i = 0; i < count; i++) {
  833                         VM_CNT_INC(v_vnodein);
  834                         VM_CNT_INC(v_vnodepgsin);
  835                         error = vnode_pager_input_smlfs(object, m[i]);
  836                         if (error)
  837                                 break;
  838                 }
  839                 return (error);
  840         }
  841 
  842         /*
  843          * A sparse file can be encountered only for a single page request,
  844          * which may not be preceded by call to vm_pager_haspage().
  845          */
  846         if (bp->b_blkno == -1) {
  847                 KASSERT(count == 1,
  848                     ("%s: array[%d] request to a sparse file %p", __func__,
  849                     count, vp));
  850                 relpbuf(bp, freecnt);
  851                 pmap_zero_page(m[0]);
  852                 KASSERT(m[0]->dirty == 0, ("%s: page %p is dirty",
  853                     __func__, m[0]));
  854                 VM_OBJECT_WLOCK(object);
  855                 m[0]->valid = VM_PAGE_BITS_ALL;
  856                 VM_OBJECT_WUNLOCK(object);
  857                 return (VM_PAGER_OK);
  858         }
  859 
  860 #ifdef INVARIANTS
  861         blkno0 = bp->b_blkno;
  862 #endif
  863         bp->b_blkno += (foff % bsize) / DEV_BSIZE;
  864 
  865         /* Recalculate blocks available after/before to pages. */
  866         poff = (foff % bsize) / PAGE_SIZE;
  867         before *= pagesperblock;
  868         before += poff;
  869         after *= pagesperblock;
  870         after += pagesperblock - (poff + 1);
  871         if (m[0]->pindex + after >= object->size)
  872                 after = object->size - 1 - m[0]->pindex;
  873         KASSERT(count <= after + 1, ("%s: %d pages asked, can do only %d",
  874             __func__, count, after + 1));
  875         after -= count - 1;
  876 
  877         /* Trim requested rbehind/rahead to possible values. */   
  878         rbehind = a_rbehind ? *a_rbehind : 0;
  879         rahead = a_rahead ? *a_rahead : 0;
  880         rbehind = min(rbehind, before);
  881         rbehind = min(rbehind, m[0]->pindex);
  882         rahead = min(rahead, after);
  883         rahead = min(rahead, object->size - m[count - 1]->pindex);
  884         /*
  885          * Check that total amount of pages fit into buf.  Trim rbehind and
  886          * rahead evenly if not.
  887          */
  888         if (rbehind + rahead + count > nitems(bp->b_pages)) {
  889                 int trim, sum;
  890 
  891                 trim = rbehind + rahead + count - nitems(bp->b_pages) + 1;
  892                 sum = rbehind + rahead;
  893                 if (rbehind == before) {
  894                         /* Roundup rbehind trim to block size. */
  895                         rbehind -= roundup(trim * rbehind / sum, pagesperblock);
  896                         if (rbehind < 0)
  897                                 rbehind = 0;
  898                 } else
  899                         rbehind -= trim * rbehind / sum;
  900                 rahead -= trim * rahead / sum;
  901         }
  902         KASSERT(rbehind + rahead + count <= nitems(bp->b_pages),
  903             ("%s: behind %d ahead %d count %d", __func__,
  904             rbehind, rahead, count));
  905 
  906         /*
  907          * Fill in the bp->b_pages[] array with requested and optional   
  908          * read behind or read ahead pages.  Read behind pages are looked
  909          * up in a backward direction, down to a first cached page.  Same
  910          * for read ahead pages, but there is no need to shift the array
  911          * in case of encountering a cached page.
  912          */
  913         i = bp->b_npages = 0;
  914         if (rbehind) {
  915                 vm_pindex_t startpindex, tpindex;
  916                 vm_page_t p;
  917 
  918                 VM_OBJECT_WLOCK(object);
  919                 startpindex = m[0]->pindex - rbehind;
  920                 if ((p = TAILQ_PREV(m[0], pglist, listq)) != NULL &&
  921                     p->pindex >= startpindex)
  922                         startpindex = p->pindex + 1;
  923 
  924                 /* tpindex is unsigned; beware of numeric underflow. */
  925                 for (tpindex = m[0]->pindex - 1;
  926                     tpindex >= startpindex && tpindex < m[0]->pindex;
  927                     tpindex--, i++) {
  928                         p = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
  929                         if (p == NULL) {
  930                                 /* Shift the array. */
  931                                 for (int j = 0; j < i; j++)
  932                                         bp->b_pages[j] = bp->b_pages[j + 
  933                                             tpindex + 1 - startpindex]; 
  934                                 break;
  935                         }
  936                         bp->b_pages[tpindex - startpindex] = p;
  937                 }
  938 
  939                 bp->b_pgbefore = i;
  940                 bp->b_npages += i;
  941                 bp->b_blkno -= IDX_TO_OFF(i) / DEV_BSIZE;
  942         } else
  943                 bp->b_pgbefore = 0;
  944 
  945         /* Requested pages. */
  946         for (int j = 0; j < count; j++, i++)
  947                 bp->b_pages[i] = m[j];
  948         bp->b_npages += count;
  949 
  950         if (rahead) {
  951                 vm_pindex_t endpindex, tpindex;
  952                 vm_page_t p;
  953 
  954                 if (!VM_OBJECT_WOWNED(object))
  955                         VM_OBJECT_WLOCK(object);
  956                 endpindex = m[count - 1]->pindex + rahead + 1;
  957                 if ((p = TAILQ_NEXT(m[count - 1], listq)) != NULL &&
  958                     p->pindex < endpindex)
  959                         endpindex = p->pindex;
  960                 if (endpindex > object->size)
  961                         endpindex = object->size;
  962 
  963                 for (tpindex = m[count - 1]->pindex + 1;
  964                     tpindex < endpindex; i++, tpindex++) {
  965                         p = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
  966                         if (p == NULL)
  967                                 break;
  968                         bp->b_pages[i] = p;
  969                 }
  970 
  971                 bp->b_pgafter = i - bp->b_npages;
  972                 bp->b_npages = i;
  973         } else
  974                 bp->b_pgafter = 0;
  975 
  976         if (VM_OBJECT_WOWNED(object))
  977                 VM_OBJECT_WUNLOCK(object);
  978 
  979         /* Report back actual behind/ahead read. */
  980         if (a_rbehind)
  981                 *a_rbehind = bp->b_pgbefore;
  982         if (a_rahead)
  983                 *a_rahead = bp->b_pgafter;
  984 
  985 #ifdef INVARIANTS
  986         KASSERT(bp->b_npages <= nitems(bp->b_pages),
  987             ("%s: buf %p overflowed", __func__, bp));
  988         for (int j = 1, prev = 0; j < bp->b_npages; j++) {
  989                 if (bp->b_pages[j] == bogus_page)
  990                         continue;
  991                 KASSERT(bp->b_pages[j]->pindex - bp->b_pages[prev]->pindex ==
  992                     j - prev, ("%s: pages array not consecutive, bp %p",
  993                      __func__, bp));
  994                 prev = j;
  995         }
  996 #endif
  997 
  998         /*
  999          * Recalculate first offset and bytecount with regards to read behind.
 1000          * Truncate bytecount to vnode real size and round up physical size
 1001          * for real devices.
 1002          */
 1003         foff = IDX_TO_OFF(bp->b_pages[0]->pindex);
 1004         bytecount = bp->b_npages << PAGE_SHIFT;
 1005         if ((foff + bytecount) > object->un_pager.vnp.vnp_size)
 1006                 bytecount = object->un_pager.vnp.vnp_size - foff;
 1007         secmask = bo->bo_bsize - 1;
 1008         KASSERT(secmask < PAGE_SIZE && secmask > 0,
 1009             ("%s: sector size %d too large", __func__, secmask + 1));
 1010         bytecount = (bytecount + secmask) & ~secmask;
 1011 
 1012         /*
 1013          * And map the pages to be read into the kva, if the filesystem
 1014          * requires mapped buffers.
 1015          */
 1016         if ((vp->v_mount->mnt_kern_flag & MNTK_UNMAPPED_BUFS) != 0 &&
 1017             unmapped_buf_allowed) {
 1018                 bp->b_data = unmapped_buf;
 1019                 bp->b_offset = 0;
 1020         } else {
 1021                 bp->b_data = bp->b_kvabase;
 1022                 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
 1023         }
 1024 
 1025         /* Build a minimal buffer header. */
 1026         bp->b_iocmd = BIO_READ;
 1027         KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
 1028         KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
 1029         bp->b_rcred = crhold(curthread->td_ucred);
 1030         bp->b_wcred = crhold(curthread->td_ucred);
 1031         pbgetbo(bo, bp);
 1032         bp->b_vp = vp;
 1033         bp->b_bcount = bp->b_bufsize = bp->b_runningbufspace = bytecount;
 1034         bp->b_iooffset = dbtob(bp->b_blkno);
 1035         KASSERT(IDX_TO_OFF(m[0]->pindex - bp->b_pages[0]->pindex) ==
 1036             (blkno0 - bp->b_blkno) * DEV_BSIZE +
 1037             IDX_TO_OFF(m[0]->pindex) % bsize,
 1038             ("wrong offsets bsize %d m[0] %ju b_pages[0] %ju "
 1039             "blkno0 %ju b_blkno %ju", bsize,
 1040             (uintmax_t)m[0]->pindex, (uintmax_t)bp->b_pages[0]->pindex,
 1041             (uintmax_t)blkno0, (uintmax_t)bp->b_blkno));
 1042 
 1043         atomic_add_long(&runningbufspace, bp->b_runningbufspace);
 1044         VM_CNT_INC(v_vnodein);
 1045         VM_CNT_ADD(v_vnodepgsin, bp->b_npages);
 1046 
 1047         if (iodone != NULL) { /* async */
 1048                 bp->b_pgiodone = iodone;
 1049                 bp->b_caller1 = arg;
 1050                 bp->b_iodone = vnode_pager_generic_getpages_done_async;
 1051                 bp->b_flags |= B_ASYNC;
 1052                 BUF_KERNPROC(bp);
 1053                 bstrategy(bp);
 1054                 return (VM_PAGER_OK);
 1055         } else {
 1056                 bp->b_iodone = bdone;
 1057                 bstrategy(bp);
 1058                 bwait(bp, PVM, "vnread");
 1059                 error = vnode_pager_generic_getpages_done(bp);
 1060                 for (i = 0; i < bp->b_npages; i++)
 1061                         bp->b_pages[i] = NULL;
 1062                 bp->b_vp = NULL;
 1063                 pbrelbo(bp);
 1064                 relpbuf(bp, &vnode_pbuf_freecnt);
 1065                 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
 1066         }
 1067 }
 1068 
 1069 static void
 1070 vnode_pager_generic_getpages_done_async(struct buf *bp)
 1071 {
 1072         int error;
 1073 
 1074         error = vnode_pager_generic_getpages_done(bp);
 1075         /* Run the iodone upon the requested range. */
 1076         bp->b_pgiodone(bp->b_caller1, bp->b_pages + bp->b_pgbefore,
 1077             bp->b_npages - bp->b_pgbefore - bp->b_pgafter, error);
 1078         for (int i = 0; i < bp->b_npages; i++)
 1079                 bp->b_pages[i] = NULL;
 1080         bp->b_vp = NULL;
 1081         pbrelbo(bp);
 1082         relpbuf(bp, &vnode_async_pbuf_freecnt);
 1083 }
 1084 
 1085 static int
 1086 vnode_pager_generic_getpages_done(struct buf *bp)
 1087 {
 1088         vm_object_t object;
 1089         off_t tfoff, nextoff;
 1090         int i, error;
 1091 
 1092         error = (bp->b_ioflags & BIO_ERROR) != 0 ? EIO : 0;
 1093         object = bp->b_vp->v_object;
 1094 
 1095         if (error == 0 && bp->b_bcount != bp->b_npages * PAGE_SIZE) {
 1096                 if (!buf_mapped(bp)) {
 1097                         bp->b_data = bp->b_kvabase;
 1098                         pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages,
 1099                             bp->b_npages);
 1100                 }
 1101                 bzero(bp->b_data + bp->b_bcount,
 1102                     PAGE_SIZE * bp->b_npages - bp->b_bcount);
 1103         }
 1104         if (buf_mapped(bp)) {
 1105                 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages);
 1106                 bp->b_data = unmapped_buf;
 1107         }
 1108 
 1109         VM_OBJECT_WLOCK(object);
 1110         for (i = 0, tfoff = IDX_TO_OFF(bp->b_pages[0]->pindex);
 1111             i < bp->b_npages; i++, tfoff = nextoff) {
 1112                 vm_page_t mt;
 1113 
 1114                 nextoff = tfoff + PAGE_SIZE;
 1115                 mt = bp->b_pages[i];
 1116 
 1117                 if (nextoff <= object->un_pager.vnp.vnp_size) {
 1118                         /*
 1119                          * Read filled up entire page.
 1120                          */
 1121                         mt->valid = VM_PAGE_BITS_ALL;
 1122                         KASSERT(mt->dirty == 0,
 1123                             ("%s: page %p is dirty", __func__, mt));
 1124                         KASSERT(!pmap_page_is_mapped(mt),
 1125                             ("%s: page %p is mapped", __func__, mt));
 1126                 } else {
 1127                         /*
 1128                          * Read did not fill up entire page.
 1129                          *
 1130                          * Currently we do not set the entire page valid,
 1131                          * we just try to clear the piece that we couldn't
 1132                          * read.
 1133                          */
 1134                         vm_page_set_valid_range(mt, 0,
 1135                             object->un_pager.vnp.vnp_size - tfoff);
 1136                         KASSERT((mt->dirty & vm_page_bits(0,
 1137                             object->un_pager.vnp.vnp_size - tfoff)) == 0,
 1138                             ("%s: page %p is dirty", __func__, mt));
 1139                 }
 1140 
 1141                 if (i < bp->b_pgbefore || i >= bp->b_npages - bp->b_pgafter)
 1142                         vm_page_readahead_finish(mt);
 1143         }
 1144         VM_OBJECT_WUNLOCK(object);
 1145         if (error != 0)
 1146                 printf("%s: I/O read error %d\n", __func__, error);
 1147 
 1148         return (error);
 1149 }
 1150 
 1151 /*
 1152  * EOPNOTSUPP is no longer legal.  For local media VFS's that do not
 1153  * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to
 1154  * vnode_pager_generic_putpages() to implement the previous behaviour.
 1155  *
 1156  * All other FS's should use the bypass to get to the local media
 1157  * backing vp's VOP_PUTPAGES.
 1158  */
 1159 static void
 1160 vnode_pager_putpages(vm_object_t object, vm_page_t *m, int count,
 1161     int flags, int *rtvals)
 1162 {
 1163         int rtval;
 1164         struct vnode *vp;
 1165         int bytes = count * PAGE_SIZE;
 1166 
 1167         /*
 1168          * Force synchronous operation if we are extremely low on memory
 1169          * to prevent a low-memory deadlock.  VOP operations often need to
 1170          * allocate more memory to initiate the I/O ( i.e. do a BMAP
 1171          * operation ).  The swapper handles the case by limiting the amount
 1172          * of asynchronous I/O, but that sort of solution doesn't scale well
 1173          * for the vnode pager without a lot of work.
 1174          *
 1175          * Also, the backing vnode's iodone routine may not wake the pageout
 1176          * daemon up.  This should be probably be addressed XXX.
 1177          */
 1178 
 1179         if (vm_page_count_min())
 1180                 flags |= VM_PAGER_PUT_SYNC;
 1181 
 1182         /*
 1183          * Call device-specific putpages function
 1184          */
 1185         vp = object->handle;
 1186         VM_OBJECT_WUNLOCK(object);
 1187         rtval = VOP_PUTPAGES(vp, m, bytes, flags, rtvals);
 1188         KASSERT(rtval != EOPNOTSUPP, 
 1189             ("vnode_pager: stale FS putpages\n"));
 1190         VM_OBJECT_WLOCK(object);
 1191 }
 1192 
 1193 static int
 1194 vn_off2bidx(vm_ooffset_t offset)
 1195 {
 1196 
 1197         return ((offset & PAGE_MASK) / DEV_BSIZE);
 1198 }
 1199 
 1200 static bool
 1201 vn_dirty_blk(vm_page_t m, vm_ooffset_t offset)
 1202 {
 1203 
 1204         KASSERT(IDX_TO_OFF(m->pindex) <= offset &&
 1205             offset < IDX_TO_OFF(m->pindex + 1),
 1206             ("page %p pidx %ju offset %ju", m, (uintmax_t)m->pindex,
 1207             (uintmax_t)offset));
 1208         return ((m->dirty & ((vm_page_bits_t)1 << vn_off2bidx(offset))) != 0);
 1209 }
 1210 
 1211 /*
 1212  * This is now called from local media FS's to operate against their
 1213  * own vnodes if they fail to implement VOP_PUTPAGES.
 1214  *
 1215  * This is typically called indirectly via the pageout daemon and
 1216  * clustering has already typically occurred, so in general we ask the
 1217  * underlying filesystem to write the data out asynchronously rather
 1218  * then delayed.
 1219  */
 1220 int
 1221 vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *ma, int bytecount,
 1222     int flags, int *rtvals)
 1223 {
 1224         vm_object_t object;
 1225         vm_page_t m;
 1226         vm_ooffset_t maxblksz, next_offset, poffset, prev_offset;
 1227         struct uio auio;
 1228         struct iovec aiov;
 1229         off_t prev_resid, wrsz;
 1230         int count, error, i, maxsize, ncount, pgoff, ppscheck;
 1231         bool in_hole;
 1232         static struct timeval lastfail;
 1233         static int curfail;
 1234 
 1235         object = vp->v_object;
 1236         count = bytecount / PAGE_SIZE;
 1237 
 1238         for (i = 0; i < count; i++)
 1239                 rtvals[i] = VM_PAGER_ERROR;
 1240 
 1241         if ((int64_t)ma[0]->pindex < 0) {
 1242                 printf("vnode_pager_generic_putpages: "
 1243                     "attempt to write meta-data 0x%jx(%lx)\n",
 1244                     (uintmax_t)ma[0]->pindex, (u_long)ma[0]->dirty);
 1245                 rtvals[0] = VM_PAGER_BAD;
 1246                 return (VM_PAGER_BAD);
 1247         }
 1248 
 1249         maxsize = count * PAGE_SIZE;
 1250         ncount = count;
 1251 
 1252         poffset = IDX_TO_OFF(ma[0]->pindex);
 1253 
 1254         /*
 1255          * If the page-aligned write is larger then the actual file we
 1256          * have to invalidate pages occurring beyond the file EOF.  However,
 1257          * there is an edge case where a file may not be page-aligned where
 1258          * the last page is partially invalid.  In this case the filesystem
 1259          * may not properly clear the dirty bits for the entire page (which
 1260          * could be VM_PAGE_BITS_ALL due to the page having been mmap()d).
 1261          * With the page locked we are free to fix-up the dirty bits here.
 1262          *
 1263          * We do not under any circumstances truncate the valid bits, as
 1264          * this will screw up bogus page replacement.
 1265          */
 1266         VM_OBJECT_RLOCK(object);
 1267         if (maxsize + poffset > object->un_pager.vnp.vnp_size) {
 1268                 if (!VM_OBJECT_TRYUPGRADE(object)) {
 1269                         VM_OBJECT_RUNLOCK(object);
 1270                         VM_OBJECT_WLOCK(object);
 1271                         if (maxsize + poffset <= object->un_pager.vnp.vnp_size)
 1272                                 goto downgrade;
 1273                 }
 1274                 if (object->un_pager.vnp.vnp_size > poffset) {
 1275                         maxsize = object->un_pager.vnp.vnp_size - poffset;
 1276                         ncount = btoc(maxsize);
 1277                         if ((pgoff = (int)maxsize & PAGE_MASK) != 0) {
 1278                                 pgoff = roundup2(pgoff, DEV_BSIZE);
 1279 
 1280                                 /*
 1281                                  * If the object is locked and the following
 1282                                  * conditions hold, then the page's dirty
 1283                                  * field cannot be concurrently changed by a
 1284                                  * pmap operation.
 1285                                  */
 1286                                 m = ma[ncount - 1];
 1287                                 vm_page_assert_sbusied(m);
 1288                                 KASSERT(!pmap_page_is_write_mapped(m),
 1289                 ("vnode_pager_generic_putpages: page %p is not read-only", m));
 1290                                 MPASS(m->dirty != 0);
 1291                                 vm_page_clear_dirty(m, pgoff, PAGE_SIZE -
 1292                                     pgoff);
 1293                         }
 1294                 } else {
 1295                         maxsize = 0;
 1296                         ncount = 0;
 1297                 }
 1298                 for (i = ncount; i < count; i++)
 1299                         rtvals[i] = VM_PAGER_BAD;
 1300 downgrade:
 1301                 VM_OBJECT_LOCK_DOWNGRADE(object);
 1302         }
 1303 
 1304         auio.uio_iov = &aiov;
 1305         auio.uio_segflg = UIO_NOCOPY;
 1306         auio.uio_rw = UIO_WRITE;
 1307         auio.uio_td = NULL;
 1308         maxblksz = roundup2(poffset + maxsize, DEV_BSIZE);
 1309 
 1310         for (prev_offset = poffset; prev_offset < maxblksz;) {
 1311                 /* Skip clean blocks. */
 1312                 for (in_hole = true; in_hole && prev_offset < maxblksz;) {
 1313                         m = ma[OFF_TO_IDX(prev_offset - poffset)];
 1314                         for (i = vn_off2bidx(prev_offset);
 1315                             i < sizeof(vm_page_bits_t) * NBBY &&
 1316                             prev_offset < maxblksz; i++) {
 1317                                 if (vn_dirty_blk(m, prev_offset)) {
 1318                                         in_hole = false;
 1319                                         break;
 1320                                 }
 1321                                 prev_offset += DEV_BSIZE;
 1322                         }
 1323                 }
 1324                 if (in_hole)
 1325                         goto write_done;
 1326 
 1327                 /* Find longest run of dirty blocks. */
 1328                 for (next_offset = prev_offset; next_offset < maxblksz;) {
 1329                         m = ma[OFF_TO_IDX(next_offset - poffset)];
 1330                         for (i = vn_off2bidx(next_offset);
 1331                             i < sizeof(vm_page_bits_t) * NBBY &&
 1332                             next_offset < maxblksz; i++) {
 1333                                 if (!vn_dirty_blk(m, next_offset))
 1334                                         goto start_write;
 1335                                 next_offset += DEV_BSIZE;
 1336                         }
 1337                 }
 1338 start_write:
 1339                 if (next_offset > poffset + maxsize)
 1340                         next_offset = poffset + maxsize;
 1341 
 1342                 /*
 1343                  * Getting here requires finding a dirty block in the
 1344                  * 'skip clean blocks' loop.
 1345                  */
 1346                 MPASS(prev_offset < next_offset);
 1347 
 1348                 VM_OBJECT_RUNLOCK(object);
 1349                 aiov.iov_base = NULL;
 1350                 auio.uio_iovcnt = 1;
 1351                 auio.uio_offset = prev_offset;
 1352                 prev_resid = auio.uio_resid = aiov.iov_len = next_offset -
 1353                     prev_offset;
 1354                 error = VOP_WRITE(vp, &auio,
 1355                     vnode_pager_putpages_ioflags(flags), curthread->td_ucred);
 1356 
 1357                 wrsz = prev_resid - auio.uio_resid;
 1358                 if (wrsz == 0) {
 1359                         if (ppsratecheck(&lastfail, &curfail, 1) != 0) {
 1360                                 vn_printf(vp, "vnode_pager_putpages: "
 1361                                     "zero-length write at %ju resid %zd\n",
 1362                                     auio.uio_offset, auio.uio_resid);
 1363                         }
 1364                         VM_OBJECT_RLOCK(object);
 1365                         break;
 1366                 }
 1367 
 1368                 /* Adjust the starting offset for next iteration. */
 1369                 prev_offset += wrsz;
 1370                 MPASS(auio.uio_offset == prev_offset);
 1371 
 1372                 ppscheck = 0;
 1373                 if (error != 0 && (ppscheck = ppsratecheck(&lastfail,
 1374                     &curfail, 1)) != 0)
 1375                         vn_printf(vp, "vnode_pager_putpages: I/O error %d\n",
 1376                             error);
 1377                 if (auio.uio_resid != 0 && (ppscheck != 0 ||
 1378                     ppsratecheck(&lastfail, &curfail, 1) != 0))
 1379                         vn_printf(vp, "vnode_pager_putpages: residual I/O %zd "
 1380                             "at %ju\n", auio.uio_resid,
 1381                             (uintmax_t)ma[0]->pindex);
 1382                 VM_OBJECT_RLOCK(object);
 1383                 if (error != 0 || auio.uio_resid != 0)
 1384                         break;
 1385         }
 1386 write_done:
 1387         /* Mark completely processed pages. */
 1388         for (i = 0; i < OFF_TO_IDX(prev_offset - poffset); i++)
 1389                 rtvals[i] = VM_PAGER_OK;
 1390         /* Mark partial EOF page. */
 1391         if (prev_offset == poffset + maxsize && (prev_offset & PAGE_MASK) != 0)
 1392                 rtvals[i++] = VM_PAGER_OK;
 1393         /* Unwritten pages in range, free bonus if the page is clean. */
 1394         for (; i < ncount; i++)
 1395                 rtvals[i] = ma[i]->dirty == 0 ? VM_PAGER_OK : VM_PAGER_ERROR;
 1396         VM_OBJECT_RUNLOCK(object);
 1397         VM_CNT_ADD(v_vnodepgsout, i);
 1398         VM_CNT_INC(v_vnodeout);
 1399         return (rtvals[0]);
 1400 }
 1401 
 1402 int
 1403 vnode_pager_putpages_ioflags(int pager_flags)
 1404 {
 1405         int ioflags;
 1406 
 1407         /*
 1408          * Pageouts are already clustered, use IO_ASYNC to force a
 1409          * bawrite() rather then a bdwrite() to prevent paging I/O
 1410          * from saturating the buffer cache.  Dummy-up the sequential
 1411          * heuristic to cause large ranges to cluster.  If neither
 1412          * IO_SYNC or IO_ASYNC is set, the system decides how to
 1413          * cluster.
 1414          */
 1415         ioflags = IO_VMIO;
 1416         if ((pager_flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL)) != 0)
 1417                 ioflags |= IO_SYNC;
 1418         else if ((pager_flags & VM_PAGER_CLUSTER_OK) == 0)
 1419                 ioflags |= IO_ASYNC;
 1420         ioflags |= (pager_flags & VM_PAGER_PUT_INVAL) != 0 ? IO_INVAL: 0;
 1421         ioflags |= (pager_flags & VM_PAGER_PUT_NOREUSE) != 0 ? IO_NOREUSE : 0;
 1422         ioflags |= IO_SEQMAX << IO_SEQSHIFT;
 1423         return (ioflags);
 1424 }
 1425 
 1426 /*
 1427  * vnode_pager_undirty_pages().
 1428  *
 1429  * A helper to mark pages as clean after pageout that was possibly
 1430  * done with a short write.  The lpos argument specifies the page run
 1431  * length in bytes, and the written argument specifies how many bytes
 1432  * were actually written.  eof is the offset past the last valid byte
 1433  * in the vnode using the absolute file position of the first byte in
 1434  * the run as the base from which it is computed.
 1435  */
 1436 void
 1437 vnode_pager_undirty_pages(vm_page_t *ma, int *rtvals, int written, off_t eof,
 1438     int lpos)
 1439 {
 1440         vm_object_t obj;
 1441         int i, pos, pos_devb;
 1442 
 1443         if (written == 0 && eof >= lpos)
 1444                 return;
 1445         obj = ma[0]->object;
 1446         VM_OBJECT_WLOCK(obj);
 1447         for (i = 0, pos = 0; pos < written; i++, pos += PAGE_SIZE) {
 1448                 if (pos < trunc_page(written)) {
 1449                         rtvals[i] = VM_PAGER_OK;
 1450                         vm_page_undirty(ma[i]);
 1451                 } else {
 1452                         /* Partially written page. */
 1453                         rtvals[i] = VM_PAGER_AGAIN;
 1454                         vm_page_clear_dirty(ma[i], 0, written & PAGE_MASK);
 1455                 }
 1456         }
 1457         if (eof >= lpos) /* avoid truncation */
 1458                 goto done;
 1459         for (pos = eof, i = OFF_TO_IDX(trunc_page(pos)); pos < lpos; i++) {
 1460                 if (pos != trunc_page(pos)) {
 1461                         /*
 1462                          * The page contains the last valid byte in
 1463                          * the vnode, mark the rest of the page as
 1464                          * clean, potentially making the whole page
 1465                          * clean.
 1466                          */
 1467                         pos_devb = roundup2(pos & PAGE_MASK, DEV_BSIZE);
 1468                         vm_page_clear_dirty(ma[i], pos_devb, PAGE_SIZE -
 1469                             pos_devb);
 1470 
 1471                         /*
 1472                          * If the page was cleaned, report the pageout
 1473                          * on it as successful.  msync() no longer
 1474                          * needs to write out the page, endlessly
 1475                          * creating write requests and dirty buffers.
 1476                          */
 1477                         if (ma[i]->dirty == 0)
 1478                                 rtvals[i] = VM_PAGER_OK;
 1479 
 1480                         pos = round_page(pos);
 1481                 } else {
 1482                         /* vm_pageout_flush() clears dirty */
 1483                         rtvals[i] = VM_PAGER_BAD;
 1484                         pos += PAGE_SIZE;
 1485                 }
 1486         }
 1487 done:
 1488         VM_OBJECT_WUNLOCK(obj);
 1489 }
 1490 
 1491 void
 1492 vnode_pager_update_writecount(vm_object_t object, vm_offset_t start,
 1493     vm_offset_t end)
 1494 {
 1495         struct vnode *vp;
 1496         vm_ooffset_t old_wm;
 1497 
 1498         VM_OBJECT_WLOCK(object);
 1499         if (object->type != OBJT_VNODE) {
 1500                 VM_OBJECT_WUNLOCK(object);
 1501                 return;
 1502         }
 1503         old_wm = object->un_pager.vnp.writemappings;
 1504         object->un_pager.vnp.writemappings += (vm_ooffset_t)end - start;
 1505         vp = object->handle;
 1506         if (old_wm == 0 && object->un_pager.vnp.writemappings != 0) {
 1507                 ASSERT_VOP_ELOCKED(vp, "v_writecount inc");
 1508                 VOP_ADD_WRITECOUNT(vp, 1);
 1509                 CTR3(KTR_VFS, "%s: vp %p v_writecount increased to %d",
 1510                     __func__, vp, vp->v_writecount);
 1511         } else if (old_wm != 0 && object->un_pager.vnp.writemappings == 0) {
 1512                 ASSERT_VOP_ELOCKED(vp, "v_writecount dec");
 1513                 VOP_ADD_WRITECOUNT(vp, -1);
 1514                 CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
 1515                     __func__, vp, vp->v_writecount);
 1516         }
 1517         VM_OBJECT_WUNLOCK(object);
 1518 }
 1519 
 1520 void
 1521 vnode_pager_release_writecount(vm_object_t object, vm_offset_t start,
 1522     vm_offset_t end)
 1523 {
 1524         struct vnode *vp;
 1525         struct mount *mp;
 1526         vm_offset_t inc;
 1527 
 1528         VM_OBJECT_WLOCK(object);
 1529 
 1530         /*
 1531          * First, recheck the object type to account for the race when
 1532          * the vnode is reclaimed.
 1533          */
 1534         if (object->type != OBJT_VNODE) {
 1535                 VM_OBJECT_WUNLOCK(object);
 1536                 return;
 1537         }
 1538 
 1539         /*
 1540          * Optimize for the case when writemappings is not going to
 1541          * zero.
 1542          */
 1543         inc = end - start;
 1544         if (object->un_pager.vnp.writemappings != inc) {
 1545                 object->un_pager.vnp.writemappings -= inc;
 1546                 VM_OBJECT_WUNLOCK(object);
 1547                 return;
 1548         }
 1549 
 1550         vp = object->handle;
 1551         vhold(vp);
 1552         VM_OBJECT_WUNLOCK(object);
 1553         mp = NULL;
 1554         vn_start_write(vp, &mp, V_WAIT);
 1555         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 1556 
 1557         /*
 1558          * Decrement the object's writemappings, by swapping the start
 1559          * and end arguments for vnode_pager_update_writecount().  If
 1560          * there was not a race with vnode reclaimation, then the
 1561          * vnode's v_writecount is decremented.
 1562          */
 1563         vnode_pager_update_writecount(object, end, start);
 1564         VOP_UNLOCK(vp, 0);
 1565         vdrop(vp);
 1566         if (mp != NULL)
 1567                 vn_finished_write(mp);
 1568 }

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