The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
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("$FreeBSD$");
   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 static void vnode_pager_update_writecount(vm_object_t, vm_offset_t,
  101     vm_offset_t);
  102 static void vnode_pager_release_writecount(vm_object_t, vm_offset_t,
  103     vm_offset_t);
  104 
  105 struct pagerops vnodepagerops = {
  106         .pgo_alloc =    vnode_pager_alloc,
  107         .pgo_dealloc =  vnode_pager_dealloc,
  108         .pgo_getpages = vnode_pager_getpages,
  109         .pgo_getpages_async = vnode_pager_getpages_async,
  110         .pgo_putpages = vnode_pager_putpages,
  111         .pgo_haspage =  vnode_pager_haspage,
  112         .pgo_update_writecount = vnode_pager_update_writecount,
  113         .pgo_release_writecount = vnode_pager_release_writecount,
  114 };
  115 
  116 int vnode_pbuf_freecnt;
  117 int vnode_async_pbuf_freecnt;
  118 
  119 static struct domainset *vnode_domainset = NULL;
  120 
  121 SYSCTL_PROC(_debug, OID_AUTO, vnode_domainset, CTLTYPE_STRING | CTLFLAG_RW,
  122     &vnode_domainset, 0, sysctl_handle_domainset, "A",
  123     "Default vnode NUMA policy");
  124 
  125 /* Create the VM system backing object for this vnode */
  126 int
  127 vnode_create_vobject(struct vnode *vp, off_t isize, struct thread *td)
  128 {
  129         vm_object_t object;
  130         vm_ooffset_t size = isize;
  131         struct vattr va;
  132 
  133         if (!vn_isdisk(vp, NULL) && vn_canvmio(vp) == FALSE)
  134                 return (0);
  135 
  136         while ((object = vp->v_object) != NULL) {
  137                 VM_OBJECT_WLOCK(object);
  138                 if (!(object->flags & OBJ_DEAD)) {
  139                         VM_OBJECT_WUNLOCK(object);
  140                         return (0);
  141                 }
  142                 VOP_UNLOCK(vp, 0);
  143                 vm_object_set_flag(object, OBJ_DISCONNECTWNT);
  144                 VM_OBJECT_SLEEP(object, object, PDROP | PVM, "vodead", 0);
  145                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
  146         }
  147 
  148         if (size == 0) {
  149                 if (vn_isdisk(vp, NULL)) {
  150                         size = IDX_TO_OFF(INT_MAX);
  151                 } else {
  152                         if (VOP_GETATTR(vp, &va, td->td_ucred))
  153                                 return (0);
  154                         size = va.va_size;
  155                 }
  156         }
  157 
  158         object = vnode_pager_alloc(vp, size, 0, 0, td->td_ucred);
  159         /*
  160          * Dereference the reference we just created.  This assumes
  161          * that the object is associated with the vp.
  162          */
  163         VM_OBJECT_WLOCK(object);
  164         object->ref_count--;
  165         VM_OBJECT_WUNLOCK(object);
  166         vrele(vp);
  167 
  168         KASSERT(vp->v_object != NULL, ("vnode_create_vobject: NULL object"));
  169 
  170         return (0);
  171 }
  172 
  173 void
  174 vnode_destroy_vobject(struct vnode *vp)
  175 {
  176         struct vm_object *obj;
  177 
  178         obj = vp->v_object;
  179         if (obj == NULL)
  180                 return;
  181         ASSERT_VOP_ELOCKED(vp, "vnode_destroy_vobject");
  182         VM_OBJECT_WLOCK(obj);
  183         umtx_shm_object_terminated(obj);
  184         if (obj->ref_count == 0) {
  185                 /*
  186                  * don't double-terminate the object
  187                  */
  188                 if ((obj->flags & OBJ_DEAD) == 0) {
  189                         vm_object_terminate(obj);
  190                 } else {
  191                         /*
  192                          * Waiters were already handled during object
  193                          * termination.  The exclusive vnode lock hopefully
  194                          * prevented new waiters from referencing the dying
  195                          * object.
  196                          */
  197                         KASSERT((obj->flags & OBJ_DISCONNECTWNT) == 0,
  198                             ("OBJ_DISCONNECTWNT set obj %p flags %x",
  199                             obj, obj->flags));
  200                         vp->v_object = NULL;
  201                         VM_OBJECT_WUNLOCK(obj);
  202                 }
  203         } else {
  204                 /*
  205                  * Woe to the process that tries to page now :-).
  206                  */
  207                 vm_pager_deallocate(obj);
  208                 VM_OBJECT_WUNLOCK(obj);
  209         }
  210         KASSERT(vp->v_object == NULL, ("vp %p obj %p", vp, vp->v_object));
  211 }
  212 
  213 
  214 /*
  215  * Allocate (or lookup) pager for a vnode.
  216  * Handle is a vnode pointer.
  217  *
  218  * MPSAFE
  219  */
  220 vm_object_t
  221 vnode_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
  222     vm_ooffset_t offset, struct ucred *cred)
  223 {
  224         vm_object_t object;
  225         struct vnode *vp;
  226 
  227         /*
  228          * Pageout to vnode, no can do yet.
  229          */
  230         if (handle == NULL)
  231                 return (NULL);
  232 
  233         vp = (struct vnode *) handle;
  234 
  235         /*
  236          * If the object is being terminated, wait for it to
  237          * go away.
  238          */
  239 retry:
  240         while ((object = vp->v_object) != NULL) {
  241                 VM_OBJECT_WLOCK(object);
  242                 if ((object->flags & OBJ_DEAD) == 0)
  243                         break;
  244                 vm_object_set_flag(object, OBJ_DISCONNECTWNT);
  245                 VM_OBJECT_SLEEP(object, object, PDROP | PVM, "vadead", 0);
  246         }
  247 
  248         KASSERT(vp->v_usecount != 0, ("vnode_pager_alloc: no vnode reference"));
  249 
  250         if (object == NULL) {
  251                 /*
  252                  * Add an object of the appropriate size
  253                  */
  254                 object = vm_object_allocate(OBJT_VNODE, OFF_TO_IDX(round_page(size)));
  255 
  256                 object->un_pager.vnp.vnp_size = size;
  257                 object->un_pager.vnp.writemappings = 0;
  258                 object->domain.dr_policy = vnode_domainset;
  259                 object->handle = handle;
  260                 if ((vp->v_vflag & VV_VMSIZEVNLOCK) != 0) {
  261                         VM_OBJECT_WLOCK(object);
  262                         vm_object_set_flag(object, OBJ_SIZEVNLOCK);
  263                         VM_OBJECT_WUNLOCK(object);
  264                 }
  265                 VI_LOCK(vp);
  266                 if (vp->v_object != NULL) {
  267                         /*
  268                          * Object has been created while we were sleeping
  269                          */
  270                         VI_UNLOCK(vp);
  271                         VM_OBJECT_WLOCK(object);
  272                         KASSERT(object->ref_count == 1,
  273                             ("leaked ref %p %d", object, object->ref_count));
  274                         object->type = OBJT_DEAD;
  275                         object->ref_count = 0;
  276                         VM_OBJECT_WUNLOCK(object);
  277                         vm_object_destroy(object);
  278                         goto retry;
  279                 }
  280                 vp->v_object = object;
  281                 VI_UNLOCK(vp);
  282         } else {
  283                 object->ref_count++;
  284 #if VM_NRESERVLEVEL > 0
  285                 vm_object_color(object, 0);
  286 #endif
  287                 VM_OBJECT_WUNLOCK(object);
  288         }
  289         vrefact(vp);
  290         return (object);
  291 }
  292 
  293 /*
  294  *      The object must be locked.
  295  */
  296 static void
  297 vnode_pager_dealloc(vm_object_t object)
  298 {
  299         struct vnode *vp;
  300         int refs;
  301 
  302         vp = object->handle;
  303         if (vp == NULL)
  304                 panic("vnode_pager_dealloc: pager already dealloced");
  305 
  306         VM_OBJECT_ASSERT_WLOCKED(object);
  307         vm_object_pip_wait(object, "vnpdea");
  308         refs = object->ref_count;
  309 
  310         object->handle = NULL;
  311         object->type = OBJT_DEAD;
  312         if (object->flags & OBJ_DISCONNECTWNT) {
  313                 vm_object_clear_flag(object, OBJ_DISCONNECTWNT);
  314                 wakeup(object);
  315         }
  316         ASSERT_VOP_ELOCKED(vp, "vnode_pager_dealloc");
  317         if (object->un_pager.vnp.writemappings > 0) {
  318                 object->un_pager.vnp.writemappings = 0;
  319                 VOP_ADD_WRITECOUNT_CHECKED(vp, -1);
  320                 CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
  321                     __func__, vp, vp->v_writecount);
  322         }
  323         vp->v_object = NULL;
  324         VI_LOCK(vp);
  325 
  326         /*
  327          * vm_map_entry_set_vnode_text() cannot reach this vnode by
  328          * following object->handle.  Clear all text references now.
  329          * This also clears the transient references from
  330          * kern_execve(), which is fine because dead_vnodeops uses nop
  331          * for VOP_UNSET_TEXT().
  332          */
  333         if (vp->v_writecount < 0)
  334                 vp->v_writecount = 0;
  335         VI_UNLOCK(vp);
  336         VM_OBJECT_WUNLOCK(object);
  337         while (refs-- > 0)
  338                 vunref(vp);
  339         VM_OBJECT_WLOCK(object);
  340 }
  341 
  342 static boolean_t
  343 vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
  344     int *after)
  345 {
  346         struct vnode *vp = object->handle;
  347         daddr_t bn;
  348         int err;
  349         daddr_t reqblock;
  350         int poff;
  351         int bsize;
  352         int pagesperblock, blocksperpage;
  353 
  354         VM_OBJECT_ASSERT_WLOCKED(object);
  355         /*
  356          * If no vp or vp is doomed or marked transparent to VM, we do not
  357          * have the page.
  358          */
  359         if (vp == NULL || vp->v_iflag & VI_DOOMED)
  360                 return FALSE;
  361         /*
  362          * If the offset is beyond end of file we do
  363          * not have the page.
  364          */
  365         if (IDX_TO_OFF(pindex) >= object->un_pager.vnp.vnp_size)
  366                 return FALSE;
  367 
  368         bsize = vp->v_mount->mnt_stat.f_iosize;
  369         pagesperblock = bsize / PAGE_SIZE;
  370         blocksperpage = 0;
  371         if (pagesperblock > 0) {
  372                 reqblock = pindex / pagesperblock;
  373         } else {
  374                 blocksperpage = (PAGE_SIZE / bsize);
  375                 reqblock = pindex * blocksperpage;
  376         }
  377         VM_OBJECT_WUNLOCK(object);
  378         err = VOP_BMAP(vp, reqblock, NULL, &bn, after, before);
  379         VM_OBJECT_WLOCK(object);
  380         if (err)
  381                 return TRUE;
  382         if (bn == -1)
  383                 return FALSE;
  384         if (pagesperblock > 0) {
  385                 poff = pindex - (reqblock * pagesperblock);
  386                 if (before) {
  387                         *before *= pagesperblock;
  388                         *before += poff;
  389                 }
  390                 if (after) {
  391                         /*
  392                          * The BMAP vop can report a partial block in the
  393                          * 'after', but must not report blocks after EOF.
  394                          * Assert the latter, and truncate 'after' in case
  395                          * of the former.
  396                          */
  397                         KASSERT((reqblock + *after) * pagesperblock <
  398                             roundup2(object->size, pagesperblock),
  399                             ("%s: reqblock %jd after %d size %ju", __func__,
  400                             (intmax_t )reqblock, *after,
  401                             (uintmax_t )object->size));
  402                         *after *= pagesperblock;
  403                         *after += pagesperblock - (poff + 1);
  404                         if (pindex + *after >= object->size)
  405                                 *after = object->size - 1 - pindex;
  406                 }
  407         } else {
  408                 if (before) {
  409                         *before /= blocksperpage;
  410                 }
  411 
  412                 if (after) {
  413                         *after /= blocksperpage;
  414                 }
  415         }
  416         return TRUE;
  417 }
  418 
  419 /*
  420  * Lets the VM system know about a change in size for a file.
  421  * We adjust our own internal size and flush any cached pages in
  422  * the associated object that are affected by the size change.
  423  *
  424  * Note: this routine may be invoked as a result of a pager put
  425  * operation (possibly at object termination time), so we must be careful.
  426  */
  427 void
  428 vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize)
  429 {
  430         vm_object_t object;
  431         vm_page_t m;
  432         vm_pindex_t nobjsize;
  433 
  434         if ((object = vp->v_object) == NULL)
  435                 return;
  436 #ifdef DEBUG_VFS_LOCKS
  437         {
  438                 struct mount *mp;
  439 
  440                 mp = vp->v_mount;
  441                 if (mp != NULL && (mp->mnt_kern_flag & MNTK_VMSETSIZE_BUG) == 0)
  442                         assert_vop_elocked(vp,
  443                             "vnode_pager_setsize and not locked vnode");
  444         }
  445 #endif
  446         VM_OBJECT_WLOCK(object);
  447         if (object->type == OBJT_DEAD) {
  448                 VM_OBJECT_WUNLOCK(object);
  449                 return;
  450         }
  451         KASSERT(object->type == OBJT_VNODE,
  452             ("not vnode-backed object %p", object));
  453         if (nsize == object->un_pager.vnp.vnp_size) {
  454                 /*
  455                  * Hasn't changed size
  456                  */
  457                 VM_OBJECT_WUNLOCK(object);
  458                 return;
  459         }
  460         nobjsize = OFF_TO_IDX(nsize + PAGE_MASK);
  461         if (nsize < object->un_pager.vnp.vnp_size) {
  462                 /*
  463                  * File has shrunk. Toss any cached pages beyond the new EOF.
  464                  */
  465                 if (nobjsize < object->size)
  466                         vm_object_page_remove(object, nobjsize, object->size,
  467                             0);
  468                 /*
  469                  * this gets rid of garbage at the end of a page that is now
  470                  * only partially backed by the vnode.
  471                  *
  472                  * XXX for some reason (I don't know yet), if we take a
  473                  * completely invalid page and mark it partially valid
  474                  * it can screw up NFS reads, so we don't allow the case.
  475                  */
  476                 if ((nsize & PAGE_MASK) &&
  477                     (m = vm_page_lookup(object, OFF_TO_IDX(nsize))) != NULL &&
  478                     m->valid != 0) {
  479                         int base = (int)nsize & PAGE_MASK;
  480                         int size = PAGE_SIZE - base;
  481 
  482                         /*
  483                          * Clear out partial-page garbage in case
  484                          * the page has been mapped.
  485                          */
  486                         pmap_zero_page_area(m, base, size);
  487 
  488                         /*
  489                          * Update the valid bits to reflect the blocks that
  490                          * have been zeroed.  Some of these valid bits may
  491                          * have already been set.
  492                          */
  493                         vm_page_set_valid_range(m, base, size);
  494 
  495                         /*
  496                          * Round "base" to the next block boundary so that the
  497                          * dirty bit for a partially zeroed block is not
  498                          * cleared.
  499                          */
  500                         base = roundup2(base, DEV_BSIZE);
  501 
  502                         /*
  503                          * Clear out partial-page dirty bits.
  504                          *
  505                          * note that we do not clear out the valid
  506                          * bits.  This would prevent bogus_page
  507                          * replacement from working properly.
  508                          */
  509                         vm_page_clear_dirty(m, base, PAGE_SIZE - base);
  510                 }
  511         }
  512         object->un_pager.vnp.vnp_size = nsize;
  513         object->size = nobjsize;
  514         VM_OBJECT_WUNLOCK(object);
  515 }
  516 
  517 /*
  518  * calculate the linear (byte) disk address of specified virtual
  519  * file address
  520  */
  521 static int
  522 vnode_pager_addr(struct vnode *vp, vm_ooffset_t address, daddr_t *rtaddress,
  523     int *run)
  524 {
  525         int bsize;
  526         int err;
  527         daddr_t vblock;
  528         daddr_t voffset;
  529 
  530         if (address < 0)
  531                 return -1;
  532 
  533         if (vp->v_iflag & VI_DOOMED)
  534                 return -1;
  535 
  536         bsize = vp->v_mount->mnt_stat.f_iosize;
  537         vblock = address / bsize;
  538         voffset = address % bsize;
  539 
  540         err = VOP_BMAP(vp, vblock, NULL, rtaddress, run, NULL);
  541         if (err == 0) {
  542                 if (*rtaddress != -1)
  543                         *rtaddress += voffset / DEV_BSIZE;
  544                 if (run) {
  545                         *run += 1;
  546                         *run *= bsize/PAGE_SIZE;
  547                         *run -= voffset/PAGE_SIZE;
  548                 }
  549         }
  550 
  551         return (err);
  552 }
  553 
  554 /*
  555  * small block filesystem vnode pager input
  556  */
  557 static int
  558 vnode_pager_input_smlfs(vm_object_t object, vm_page_t m)
  559 {
  560         struct vnode *vp;
  561         struct bufobj *bo;
  562         struct buf *bp;
  563         struct sf_buf *sf;
  564         daddr_t fileaddr;
  565         vm_offset_t bsize;
  566         vm_page_bits_t bits;
  567         int error, i;
  568 
  569         error = 0;
  570         vp = object->handle;
  571         if (vp->v_iflag & VI_DOOMED)
  572                 return VM_PAGER_BAD;
  573 
  574         bsize = vp->v_mount->mnt_stat.f_iosize;
  575 
  576         VOP_BMAP(vp, 0, &bo, 0, NULL, NULL);
  577 
  578         sf = sf_buf_alloc(m, 0);
  579 
  580         for (i = 0; i < PAGE_SIZE / bsize; i++) {
  581                 vm_ooffset_t address;
  582 
  583                 bits = vm_page_bits(i * bsize, bsize);
  584                 if (m->valid & bits)
  585                         continue;
  586 
  587                 address = IDX_TO_OFF(m->pindex) + i * bsize;
  588                 if (address >= object->un_pager.vnp.vnp_size) {
  589                         fileaddr = -1;
  590                 } else {
  591                         error = vnode_pager_addr(vp, address, &fileaddr, NULL);
  592                         if (error)
  593                                 break;
  594                 }
  595                 if (fileaddr != -1) {
  596                         bp = getpbuf(&vnode_pbuf_freecnt);
  597 
  598                         /* build a minimal buffer header */
  599                         bp->b_iocmd = BIO_READ;
  600                         bp->b_iodone = bdone;
  601                         KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
  602                         KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
  603                         bp->b_rcred = crhold(curthread->td_ucred);
  604                         bp->b_wcred = crhold(curthread->td_ucred);
  605                         bp->b_data = (caddr_t)sf_buf_kva(sf) + i * bsize;
  606                         bp->b_blkno = fileaddr;
  607                         pbgetbo(bo, bp);
  608                         bp->b_vp = vp;
  609                         bp->b_bcount = bsize;
  610                         bp->b_bufsize = bsize;
  611                         bp->b_runningbufspace = bp->b_bufsize;
  612                         atomic_add_long(&runningbufspace, bp->b_runningbufspace);
  613 
  614                         /* do the input */
  615                         bp->b_iooffset = dbtob(bp->b_blkno);
  616                         bstrategy(bp);
  617 
  618                         bwait(bp, PVM, "vnsrd");
  619 
  620                         if ((bp->b_ioflags & BIO_ERROR) != 0)
  621                                 error = EIO;
  622 
  623                         /*
  624                          * free the buffer header back to the swap buffer pool
  625                          */
  626                         bp->b_vp = NULL;
  627                         pbrelbo(bp);
  628                         relpbuf(bp, &vnode_pbuf_freecnt);
  629                         if (error)
  630                                 break;
  631                 } else
  632                         bzero((caddr_t)sf_buf_kva(sf) + i * bsize, bsize);
  633                 KASSERT((m->dirty & bits) == 0,
  634                     ("vnode_pager_input_smlfs: page %p is dirty", m));
  635                 VM_OBJECT_WLOCK(object);
  636                 m->valid |= bits;
  637                 VM_OBJECT_WUNLOCK(object);
  638         }
  639         sf_buf_free(sf);
  640         if (error) {
  641                 return VM_PAGER_ERROR;
  642         }
  643         return VM_PAGER_OK;
  644 }
  645 
  646 /*
  647  * old style vnode pager input routine
  648  */
  649 static int
  650 vnode_pager_input_old(vm_object_t object, vm_page_t m)
  651 {
  652         struct uio auio;
  653         struct iovec aiov;
  654         int error;
  655         int size;
  656         struct sf_buf *sf;
  657         struct vnode *vp;
  658 
  659         VM_OBJECT_ASSERT_WLOCKED(object);
  660         error = 0;
  661 
  662         /*
  663          * Return failure if beyond current EOF
  664          */
  665         if (IDX_TO_OFF(m->pindex) >= object->un_pager.vnp.vnp_size) {
  666                 return VM_PAGER_BAD;
  667         } else {
  668                 size = PAGE_SIZE;
  669                 if (IDX_TO_OFF(m->pindex) + size > object->un_pager.vnp.vnp_size)
  670                         size = object->un_pager.vnp.vnp_size - IDX_TO_OFF(m->pindex);
  671                 vp = object->handle;
  672                 VM_OBJECT_WUNLOCK(object);
  673 
  674                 /*
  675                  * Allocate a kernel virtual address and initialize so that
  676                  * we can use VOP_READ/WRITE routines.
  677                  */
  678                 sf = sf_buf_alloc(m, 0);
  679 
  680                 aiov.iov_base = (caddr_t)sf_buf_kva(sf);
  681                 aiov.iov_len = size;
  682                 auio.uio_iov = &aiov;
  683                 auio.uio_iovcnt = 1;
  684                 auio.uio_offset = IDX_TO_OFF(m->pindex);
  685                 auio.uio_segflg = UIO_SYSSPACE;
  686                 auio.uio_rw = UIO_READ;
  687                 auio.uio_resid = size;
  688                 auio.uio_td = curthread;
  689 
  690                 error = VOP_READ(vp, &auio, 0, curthread->td_ucred);
  691                 if (!error) {
  692                         int count = size - auio.uio_resid;
  693 
  694                         if (count == 0)
  695                                 error = EINVAL;
  696                         else if (count != PAGE_SIZE)
  697                                 bzero((caddr_t)sf_buf_kva(sf) + count,
  698                                     PAGE_SIZE - count);
  699                 }
  700                 sf_buf_free(sf);
  701 
  702                 VM_OBJECT_WLOCK(object);
  703         }
  704         KASSERT(m->dirty == 0, ("vnode_pager_input_old: page %p is dirty", m));
  705         if (!error)
  706                 m->valid = VM_PAGE_BITS_ALL;
  707         return error ? VM_PAGER_ERROR : VM_PAGER_OK;
  708 }
  709 
  710 /*
  711  * generic vnode pager input routine
  712  */
  713 
  714 /*
  715  * Local media VFS's that do not implement their own VOP_GETPAGES
  716  * should have their VOP_GETPAGES call to vnode_pager_generic_getpages()
  717  * to implement the previous behaviour.
  718  *
  719  * All other FS's should use the bypass to get to the local media
  720  * backing vp's VOP_GETPAGES.
  721  */
  722 static int
  723 vnode_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
  724     int *rahead)
  725 {
  726         struct vnode *vp;
  727         int rtval;
  728 
  729         vp = object->handle;
  730         VM_OBJECT_WUNLOCK(object);
  731         rtval = VOP_GETPAGES(vp, m, count, rbehind, rahead);
  732         KASSERT(rtval != EOPNOTSUPP,
  733             ("vnode_pager: FS getpages not implemented\n"));
  734         VM_OBJECT_WLOCK(object);
  735         return rtval;
  736 }
  737 
  738 static int
  739 vnode_pager_getpages_async(vm_object_t object, vm_page_t *m, int count,
  740     int *rbehind, int *rahead, vop_getpages_iodone_t iodone, void *arg)
  741 {
  742         struct vnode *vp;
  743         int rtval;
  744 
  745         vp = object->handle;
  746         VM_OBJECT_WUNLOCK(object);
  747         rtval = VOP_GETPAGES_ASYNC(vp, m, count, rbehind, rahead, iodone, arg);
  748         KASSERT(rtval != EOPNOTSUPP,
  749             ("vnode_pager: FS getpages_async not implemented\n"));
  750         VM_OBJECT_WLOCK(object);
  751         return (rtval);
  752 }
  753 
  754 /*
  755  * The implementation of VOP_GETPAGES() and VOP_GETPAGES_ASYNC() for
  756  * local filesystems, where partially valid pages can only occur at
  757  * the end of file.
  758  */
  759 int
  760 vnode_pager_local_getpages(struct vop_getpages_args *ap)
  761 {
  762 
  763         return (vnode_pager_generic_getpages(ap->a_vp, ap->a_m, ap->a_count,
  764             ap->a_rbehind, ap->a_rahead, NULL, NULL));
  765 }
  766 
  767 int
  768 vnode_pager_local_getpages_async(struct vop_getpages_async_args *ap)
  769 {
  770         int error;
  771 
  772         error = vnode_pager_generic_getpages(ap->a_vp, ap->a_m, ap->a_count,
  773             ap->a_rbehind, ap->a_rahead, ap->a_iodone, ap->a_arg);
  774         if (error != 0 && ap->a_iodone != NULL)
  775                 ap->a_iodone(ap->a_arg, ap->a_m, ap->a_count, error);
  776         return (error);
  777 }
  778 
  779 /*
  780  * This is now called from local media FS's to operate against their
  781  * own vnodes if they fail to implement VOP_GETPAGES.
  782  */
  783 int
  784 vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int count,
  785     int *a_rbehind, int *a_rahead, vop_getpages_iodone_t iodone, void *arg)
  786 {
  787         vm_object_t object;
  788         struct bufobj *bo;
  789         struct buf *bp;
  790         off_t foff;
  791 #ifdef INVARIANTS
  792         off_t blkno0;
  793 #endif
  794         int bsize, pagesperblock, *freecnt;
  795         int error, before, after, rbehind, rahead, poff, i;
  796         int bytecount, secmask;
  797 
  798         KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
  799             ("%s does not support devices", __func__));
  800 
  801         if (vp->v_iflag & VI_DOOMED)
  802                 return (VM_PAGER_BAD);
  803 
  804         object = vp->v_object;
  805         foff = IDX_TO_OFF(m[0]->pindex);
  806         bsize = vp->v_mount->mnt_stat.f_iosize;
  807         pagesperblock = bsize / PAGE_SIZE;
  808 
  809         KASSERT(foff < object->un_pager.vnp.vnp_size,
  810             ("%s: page %p offset beyond vp %p size", __func__, m[0], vp));
  811         KASSERT(count <= nitems(bp->b_pages),
  812             ("%s: requested %d pages", __func__, count));
  813 
  814         /*
  815          * The last page has valid blocks.  Invalid part can only
  816          * exist at the end of file, and the page is made fully valid
  817          * by zeroing in vm_pager_get_pages().
  818          */
  819         if (m[count - 1]->valid != 0 && --count == 0) {
  820                 if (iodone != NULL)
  821                         iodone(arg, m, 1, 0);
  822                 return (VM_PAGER_OK);
  823         }
  824 
  825         /*
  826          * Synchronous and asynchronous paging operations use different
  827          * free pbuf counters.  This is done to avoid asynchronous requests
  828          * to consume all pbufs.
  829          * Allocate the pbuf at the very beginning of the function, so that
  830          * if we are low on certain kind of pbufs don't even proceed to BMAP,
  831          * but sleep.
  832          */
  833         freecnt = iodone != NULL ?
  834             &vnode_async_pbuf_freecnt : &vnode_pbuf_freecnt;
  835         bp = getpbuf(freecnt);
  836 
  837         /*
  838          * Get the underlying device blocks for the file with VOP_BMAP().
  839          * If the file system doesn't support VOP_BMAP, use old way of
  840          * getting pages via VOP_READ.
  841          */
  842         error = VOP_BMAP(vp, foff / bsize, &bo, &bp->b_blkno, &after, &before);
  843         if (error == EOPNOTSUPP) {
  844                 relpbuf(bp, freecnt);
  845                 VM_OBJECT_WLOCK(object);
  846                 for (i = 0; i < count; i++) {
  847                         VM_CNT_INC(v_vnodein);
  848                         VM_CNT_INC(v_vnodepgsin);
  849                         error = vnode_pager_input_old(object, m[i]);
  850                         if (error)
  851                                 break;
  852                 }
  853                 VM_OBJECT_WUNLOCK(object);
  854                 return (error);
  855         } else if (error != 0) {
  856                 relpbuf(bp, freecnt);
  857                 return (VM_PAGER_ERROR);
  858         }
  859 
  860         /*
  861          * If the file system supports BMAP, but blocksize is smaller
  862          * than a page size, then use special small filesystem code.
  863          */
  864         if (pagesperblock == 0) {
  865                 relpbuf(bp, freecnt);
  866                 for (i = 0; i < count; i++) {
  867                         VM_CNT_INC(v_vnodein);
  868                         VM_CNT_INC(v_vnodepgsin);
  869                         error = vnode_pager_input_smlfs(object, m[i]);
  870                         if (error)
  871                                 break;
  872                 }
  873                 return (error);
  874         }
  875 
  876         /*
  877          * A sparse file can be encountered only for a single page request,
  878          * which may not be preceded by call to vm_pager_haspage().
  879          */
  880         if (bp->b_blkno == -1) {
  881                 KASSERT(count == 1,
  882                     ("%s: array[%d] request to a sparse file %p", __func__,
  883                     count, vp));
  884                 relpbuf(bp, freecnt);
  885                 pmap_zero_page(m[0]);
  886                 KASSERT(m[0]->dirty == 0, ("%s: page %p is dirty",
  887                     __func__, m[0]));
  888                 VM_OBJECT_WLOCK(object);
  889                 m[0]->valid = VM_PAGE_BITS_ALL;
  890                 VM_OBJECT_WUNLOCK(object);
  891                 return (VM_PAGER_OK);
  892         }
  893 
  894 #ifdef INVARIANTS
  895         blkno0 = bp->b_blkno;
  896 #endif
  897         bp->b_blkno += (foff % bsize) / DEV_BSIZE;
  898 
  899         /* Recalculate blocks available after/before to pages. */
  900         poff = (foff % bsize) / PAGE_SIZE;
  901         before *= pagesperblock;
  902         before += poff;
  903         after *= pagesperblock;
  904         after += pagesperblock - (poff + 1);
  905         if (m[0]->pindex + after >= object->size)
  906                 after = object->size - 1 - m[0]->pindex;
  907         KASSERT(count <= after + 1, ("%s: %d pages asked, can do only %d",
  908             __func__, count, after + 1));
  909         after -= count - 1;
  910 
  911         /* Trim requested rbehind/rahead to possible values. */   
  912         rbehind = a_rbehind ? *a_rbehind : 0;
  913         rahead = a_rahead ? *a_rahead : 0;
  914         rbehind = min(rbehind, before);
  915         rbehind = min(rbehind, m[0]->pindex);
  916         rahead = min(rahead, after);
  917         rahead = min(rahead, object->size - m[count - 1]->pindex);
  918         /*
  919          * Check that total amount of pages fit into buf.  Trim rbehind and
  920          * rahead evenly if not.
  921          */
  922         if (rbehind + rahead + count > nitems(bp->b_pages)) {
  923                 int trim, sum;
  924 
  925                 trim = rbehind + rahead + count - nitems(bp->b_pages) + 1;
  926                 sum = rbehind + rahead;
  927                 if (rbehind == before) {
  928                         /* Roundup rbehind trim to block size. */
  929                         rbehind -= roundup(trim * rbehind / sum, pagesperblock);
  930                         if (rbehind < 0)
  931                                 rbehind = 0;
  932                 } else
  933                         rbehind -= trim * rbehind / sum;
  934                 rahead -= trim * rahead / sum;
  935         }
  936         KASSERT(rbehind + rahead + count <= nitems(bp->b_pages),
  937             ("%s: behind %d ahead %d count %d", __func__,
  938             rbehind, rahead, count));
  939 
  940         /*
  941          * Fill in the bp->b_pages[] array with requested and optional   
  942          * read behind or read ahead pages.  Read behind pages are looked
  943          * up in a backward direction, down to a first cached page.  Same
  944          * for read ahead pages, but there is no need to shift the array
  945          * in case of encountering a cached page.
  946          */
  947         i = bp->b_npages = 0;
  948         if (rbehind) {
  949                 vm_pindex_t startpindex, tpindex;
  950                 vm_page_t p;
  951 
  952                 VM_OBJECT_WLOCK(object);
  953                 startpindex = m[0]->pindex - rbehind;
  954                 if ((p = TAILQ_PREV(m[0], pglist, listq)) != NULL &&
  955                     p->pindex >= startpindex)
  956                         startpindex = p->pindex + 1;
  957 
  958                 /* tpindex is unsigned; beware of numeric underflow. */
  959                 for (tpindex = m[0]->pindex - 1;
  960                     tpindex >= startpindex && tpindex < m[0]->pindex;
  961                     tpindex--, i++) {
  962                         p = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
  963                         if (p == NULL) {
  964                                 /* Shift the array. */
  965                                 for (int j = 0; j < i; j++)
  966                                         bp->b_pages[j] = bp->b_pages[j + 
  967                                             tpindex + 1 - startpindex]; 
  968                                 break;
  969                         }
  970                         bp->b_pages[tpindex - startpindex] = p;
  971                 }
  972 
  973                 bp->b_pgbefore = i;
  974                 bp->b_npages += i;
  975                 bp->b_blkno -= IDX_TO_OFF(i) / DEV_BSIZE;
  976         } else
  977                 bp->b_pgbefore = 0;
  978 
  979         /* Requested pages. */
  980         for (int j = 0; j < count; j++, i++)
  981                 bp->b_pages[i] = m[j];
  982         bp->b_npages += count;
  983 
  984         if (rahead) {
  985                 vm_pindex_t endpindex, tpindex;
  986                 vm_page_t p;
  987 
  988                 if (!VM_OBJECT_WOWNED(object))
  989                         VM_OBJECT_WLOCK(object);
  990                 endpindex = m[count - 1]->pindex + rahead + 1;
  991                 if ((p = TAILQ_NEXT(m[count - 1], listq)) != NULL &&
  992                     p->pindex < endpindex)
  993                         endpindex = p->pindex;
  994                 if (endpindex > object->size)
  995                         endpindex = object->size;
  996 
  997                 for (tpindex = m[count - 1]->pindex + 1;
  998                     tpindex < endpindex; i++, tpindex++) {
  999                         p = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
 1000                         if (p == NULL)
 1001                                 break;
 1002                         bp->b_pages[i] = p;
 1003                 }
 1004 
 1005                 bp->b_pgafter = i - bp->b_npages;
 1006                 bp->b_npages = i;
 1007         } else
 1008                 bp->b_pgafter = 0;
 1009 
 1010         if (VM_OBJECT_WOWNED(object))
 1011                 VM_OBJECT_WUNLOCK(object);
 1012 
 1013         /* Report back actual behind/ahead read. */
 1014         if (a_rbehind)
 1015                 *a_rbehind = bp->b_pgbefore;
 1016         if (a_rahead)
 1017                 *a_rahead = bp->b_pgafter;
 1018 
 1019 #ifdef INVARIANTS
 1020         KASSERT(bp->b_npages <= nitems(bp->b_pages),
 1021             ("%s: buf %p overflowed", __func__, bp));
 1022         for (int j = 1, prev = 0; j < bp->b_npages; j++) {
 1023                 if (bp->b_pages[j] == bogus_page)
 1024                         continue;
 1025                 KASSERT(bp->b_pages[j]->pindex - bp->b_pages[prev]->pindex ==
 1026                     j - prev, ("%s: pages array not consecutive, bp %p",
 1027                      __func__, bp));
 1028                 prev = j;
 1029         }
 1030 #endif
 1031 
 1032         /*
 1033          * Recalculate first offset and bytecount with regards to read behind.
 1034          * Truncate bytecount to vnode real size and round up physical size
 1035          * for real devices.
 1036          */
 1037         foff = IDX_TO_OFF(bp->b_pages[0]->pindex);
 1038         bytecount = bp->b_npages << PAGE_SHIFT;
 1039         if ((foff + bytecount) > object->un_pager.vnp.vnp_size)
 1040                 bytecount = object->un_pager.vnp.vnp_size - foff;
 1041         secmask = bo->bo_bsize - 1;
 1042         KASSERT(secmask < PAGE_SIZE && secmask > 0,
 1043             ("%s: sector size %d too large", __func__, secmask + 1));
 1044         bytecount = (bytecount + secmask) & ~secmask;
 1045 
 1046         /*
 1047          * And map the pages to be read into the kva, if the filesystem
 1048          * requires mapped buffers.
 1049          */
 1050         if ((vp->v_mount->mnt_kern_flag & MNTK_UNMAPPED_BUFS) != 0 &&
 1051             unmapped_buf_allowed) {
 1052                 bp->b_data = unmapped_buf;
 1053                 bp->b_offset = 0;
 1054         } else {
 1055                 bp->b_data = bp->b_kvabase;
 1056                 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
 1057         }
 1058 
 1059         /* Build a minimal buffer header. */
 1060         bp->b_iocmd = BIO_READ;
 1061         KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
 1062         KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
 1063         bp->b_rcred = crhold(curthread->td_ucred);
 1064         bp->b_wcred = crhold(curthread->td_ucred);
 1065         pbgetbo(bo, bp);
 1066         bp->b_vp = vp;
 1067         bp->b_bcount = bp->b_bufsize = bp->b_runningbufspace = bytecount;
 1068         bp->b_iooffset = dbtob(bp->b_blkno);
 1069         KASSERT(IDX_TO_OFF(m[0]->pindex - bp->b_pages[0]->pindex) ==
 1070             (blkno0 - bp->b_blkno) * DEV_BSIZE +
 1071             IDX_TO_OFF(m[0]->pindex) % bsize,
 1072             ("wrong offsets bsize %d m[0] %ju b_pages[0] %ju "
 1073             "blkno0 %ju b_blkno %ju", bsize,
 1074             (uintmax_t)m[0]->pindex, (uintmax_t)bp->b_pages[0]->pindex,
 1075             (uintmax_t)blkno0, (uintmax_t)bp->b_blkno));
 1076 
 1077         atomic_add_long(&runningbufspace, bp->b_runningbufspace);
 1078         VM_CNT_INC(v_vnodein);
 1079         VM_CNT_ADD(v_vnodepgsin, bp->b_npages);
 1080 
 1081         if (iodone != NULL) { /* async */
 1082                 bp->b_pgiodone = iodone;
 1083                 bp->b_caller1 = arg;
 1084                 bp->b_iodone = vnode_pager_generic_getpages_done_async;
 1085                 bp->b_flags |= B_ASYNC;
 1086                 BUF_KERNPROC(bp);
 1087                 bstrategy(bp);
 1088                 return (VM_PAGER_OK);
 1089         } else {
 1090                 bp->b_iodone = bdone;
 1091                 bstrategy(bp);
 1092                 bwait(bp, PVM, "vnread");
 1093                 error = vnode_pager_generic_getpages_done(bp);
 1094                 for (i = 0; i < bp->b_npages; i++)
 1095                         bp->b_pages[i] = NULL;
 1096                 bp->b_vp = NULL;
 1097                 pbrelbo(bp);
 1098                 relpbuf(bp, &vnode_pbuf_freecnt);
 1099                 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
 1100         }
 1101 }
 1102 
 1103 static void
 1104 vnode_pager_generic_getpages_done_async(struct buf *bp)
 1105 {
 1106         int error;
 1107 
 1108         error = vnode_pager_generic_getpages_done(bp);
 1109         /* Run the iodone upon the requested range. */
 1110         bp->b_pgiodone(bp->b_caller1, bp->b_pages + bp->b_pgbefore,
 1111             bp->b_npages - bp->b_pgbefore - bp->b_pgafter, error);
 1112         for (int i = 0; i < bp->b_npages; i++)
 1113                 bp->b_pages[i] = NULL;
 1114         bp->b_vp = NULL;
 1115         pbrelbo(bp);
 1116         relpbuf(bp, &vnode_async_pbuf_freecnt);
 1117 }
 1118 
 1119 static int
 1120 vnode_pager_generic_getpages_done(struct buf *bp)
 1121 {
 1122         vm_object_t object;
 1123         off_t tfoff, nextoff;
 1124         int i, error;
 1125 
 1126         error = (bp->b_ioflags & BIO_ERROR) != 0 ? EIO : 0;
 1127         object = bp->b_vp->v_object;
 1128 
 1129         if (error == 0 && bp->b_bcount != bp->b_npages * PAGE_SIZE) {
 1130                 if (!buf_mapped(bp)) {
 1131                         bp->b_data = bp->b_kvabase;
 1132                         pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages,
 1133                             bp->b_npages);
 1134                 }
 1135                 bzero(bp->b_data + bp->b_bcount,
 1136                     PAGE_SIZE * bp->b_npages - bp->b_bcount);
 1137         }
 1138         if (buf_mapped(bp)) {
 1139                 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages);
 1140                 bp->b_data = unmapped_buf;
 1141         }
 1142 
 1143         VM_OBJECT_WLOCK(object);
 1144         for (i = 0, tfoff = IDX_TO_OFF(bp->b_pages[0]->pindex);
 1145             i < bp->b_npages; i++, tfoff = nextoff) {
 1146                 vm_page_t mt;
 1147 
 1148                 nextoff = tfoff + PAGE_SIZE;
 1149                 mt = bp->b_pages[i];
 1150                 if (mt == bogus_page)
 1151                         continue;
 1152 
 1153                 if (nextoff <= object->un_pager.vnp.vnp_size) {
 1154                         /*
 1155                          * Read filled up entire page.
 1156                          */
 1157                         mt->valid = VM_PAGE_BITS_ALL;
 1158                         KASSERT(mt->dirty == 0,
 1159                             ("%s: page %p is dirty", __func__, mt));
 1160                         KASSERT(!pmap_page_is_mapped(mt),
 1161                             ("%s: page %p is mapped", __func__, mt));
 1162                 } else {
 1163                         /*
 1164                          * Read did not fill up entire page.
 1165                          *
 1166                          * Currently we do not set the entire page valid,
 1167                          * we just try to clear the piece that we couldn't
 1168                          * read.
 1169                          */
 1170                         vm_page_set_valid_range(mt, 0,
 1171                             object->un_pager.vnp.vnp_size - tfoff);
 1172                         KASSERT((mt->dirty & vm_page_bits(0,
 1173                             object->un_pager.vnp.vnp_size - tfoff)) == 0,
 1174                             ("%s: page %p is dirty", __func__, mt));
 1175                 }
 1176 
 1177                 if (i < bp->b_pgbefore || i >= bp->b_npages - bp->b_pgafter)
 1178                         vm_page_readahead_finish(mt);
 1179         }
 1180         VM_OBJECT_WUNLOCK(object);
 1181         if (error != 0)
 1182                 printf("%s: I/O read error %d\n", __func__, error);
 1183 
 1184         return (error);
 1185 }
 1186 
 1187 /*
 1188  * EOPNOTSUPP is no longer legal.  For local media VFS's that do not
 1189  * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to
 1190  * vnode_pager_generic_putpages() to implement the previous behaviour.
 1191  *
 1192  * All other FS's should use the bypass to get to the local media
 1193  * backing vp's VOP_PUTPAGES.
 1194  */
 1195 static void
 1196 vnode_pager_putpages(vm_object_t object, vm_page_t *m, int count,
 1197     int flags, int *rtvals)
 1198 {
 1199         int rtval;
 1200         struct vnode *vp;
 1201         int bytes = count * PAGE_SIZE;
 1202 
 1203         /*
 1204          * Force synchronous operation if we are extremely low on memory
 1205          * to prevent a low-memory deadlock.  VOP operations often need to
 1206          * allocate more memory to initiate the I/O ( i.e. do a BMAP
 1207          * operation ).  The swapper handles the case by limiting the amount
 1208          * of asynchronous I/O, but that sort of solution doesn't scale well
 1209          * for the vnode pager without a lot of work.
 1210          *
 1211          * Also, the backing vnode's iodone routine may not wake the pageout
 1212          * daemon up.  This should be probably be addressed XXX.
 1213          */
 1214 
 1215         if (vm_page_count_min())
 1216                 flags |= VM_PAGER_PUT_SYNC;
 1217 
 1218         /*
 1219          * Call device-specific putpages function
 1220          */
 1221         vp = object->handle;
 1222         VM_OBJECT_WUNLOCK(object);
 1223         rtval = VOP_PUTPAGES(vp, m, bytes, flags, rtvals);
 1224         KASSERT(rtval != EOPNOTSUPP, 
 1225             ("vnode_pager: stale FS putpages\n"));
 1226         VM_OBJECT_WLOCK(object);
 1227 }
 1228 
 1229 static int
 1230 vn_off2bidx(vm_ooffset_t offset)
 1231 {
 1232 
 1233         return ((offset & PAGE_MASK) / DEV_BSIZE);
 1234 }
 1235 
 1236 static bool
 1237 vn_dirty_blk(vm_page_t m, vm_ooffset_t offset)
 1238 {
 1239 
 1240         KASSERT(IDX_TO_OFF(m->pindex) <= offset &&
 1241             offset < IDX_TO_OFF(m->pindex + 1),
 1242             ("page %p pidx %ju offset %ju", m, (uintmax_t)m->pindex,
 1243             (uintmax_t)offset));
 1244         return ((m->dirty & ((vm_page_bits_t)1 << vn_off2bidx(offset))) != 0);
 1245 }
 1246 
 1247 /*
 1248  * This is now called from local media FS's to operate against their
 1249  * own vnodes if they fail to implement VOP_PUTPAGES.
 1250  *
 1251  * This is typically called indirectly via the pageout daemon and
 1252  * clustering has already typically occurred, so in general we ask the
 1253  * underlying filesystem to write the data out asynchronously rather
 1254  * then delayed.
 1255  */
 1256 int
 1257 vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *ma, int bytecount,
 1258     int flags, int *rtvals)
 1259 {
 1260         vm_object_t object;
 1261         vm_page_t m;
 1262         vm_ooffset_t maxblksz, next_offset, poffset, prev_offset;
 1263         struct uio auio;
 1264         struct iovec aiov;
 1265         off_t prev_resid, wrsz;
 1266         int count, error, i, maxsize, ncount, pgoff, ppscheck;
 1267         bool in_hole;
 1268         static struct timeval lastfail;
 1269         static int curfail;
 1270 
 1271         object = vp->v_object;
 1272         count = bytecount / PAGE_SIZE;
 1273 
 1274         for (i = 0; i < count; i++)
 1275                 rtvals[i] = VM_PAGER_ERROR;
 1276 
 1277         if ((int64_t)ma[0]->pindex < 0) {
 1278                 printf("vnode_pager_generic_putpages: "
 1279                     "attempt to write meta-data 0x%jx(%lx)\n",
 1280                     (uintmax_t)ma[0]->pindex, (u_long)ma[0]->dirty);
 1281                 rtvals[0] = VM_PAGER_BAD;
 1282                 return (VM_PAGER_BAD);
 1283         }
 1284 
 1285         maxsize = count * PAGE_SIZE;
 1286         ncount = count;
 1287 
 1288         poffset = IDX_TO_OFF(ma[0]->pindex);
 1289 
 1290         /*
 1291          * If the page-aligned write is larger then the actual file we
 1292          * have to invalidate pages occurring beyond the file EOF.  However,
 1293          * there is an edge case where a file may not be page-aligned where
 1294          * the last page is partially invalid.  In this case the filesystem
 1295          * may not properly clear the dirty bits for the entire page (which
 1296          * could be VM_PAGE_BITS_ALL due to the page having been mmap()d).
 1297          * With the page locked we are free to fix-up the dirty bits here.
 1298          *
 1299          * We do not under any circumstances truncate the valid bits, as
 1300          * this will screw up bogus page replacement.
 1301          */
 1302         VM_OBJECT_RLOCK(object);
 1303         if (maxsize + poffset > object->un_pager.vnp.vnp_size) {
 1304                 if (!VM_OBJECT_TRYUPGRADE(object)) {
 1305                         VM_OBJECT_RUNLOCK(object);
 1306                         VM_OBJECT_WLOCK(object);
 1307                         if (maxsize + poffset <= object->un_pager.vnp.vnp_size)
 1308                                 goto downgrade;
 1309                 }
 1310                 if (object->un_pager.vnp.vnp_size > poffset) {
 1311                         maxsize = object->un_pager.vnp.vnp_size - poffset;
 1312                         ncount = btoc(maxsize);
 1313                         if ((pgoff = (int)maxsize & PAGE_MASK) != 0) {
 1314                                 pgoff = roundup2(pgoff, DEV_BSIZE);
 1315 
 1316                                 /*
 1317                                  * If the object is locked and the following
 1318                                  * conditions hold, then the page's dirty
 1319                                  * field cannot be concurrently changed by a
 1320                                  * pmap operation.
 1321                                  */
 1322                                 m = ma[ncount - 1];
 1323                                 vm_page_assert_sbusied(m);
 1324                                 KASSERT(!pmap_page_is_write_mapped(m),
 1325                 ("vnode_pager_generic_putpages: page %p is not read-only", m));
 1326                                 MPASS(m->dirty != 0);
 1327                                 vm_page_clear_dirty(m, pgoff, PAGE_SIZE -
 1328                                     pgoff);
 1329                         }
 1330                 } else {
 1331                         maxsize = 0;
 1332                         ncount = 0;
 1333                 }
 1334                 for (i = ncount; i < count; i++)
 1335                         rtvals[i] = VM_PAGER_BAD;
 1336 downgrade:
 1337                 VM_OBJECT_LOCK_DOWNGRADE(object);
 1338         }
 1339 
 1340         auio.uio_iov = &aiov;
 1341         auio.uio_segflg = UIO_NOCOPY;
 1342         auio.uio_rw = UIO_WRITE;
 1343         auio.uio_td = NULL;
 1344         maxblksz = roundup2(poffset + maxsize, DEV_BSIZE);
 1345 
 1346         for (prev_offset = poffset; prev_offset < maxblksz;) {
 1347                 /* Skip clean blocks. */
 1348                 for (in_hole = true; in_hole && prev_offset < maxblksz;) {
 1349                         m = ma[OFF_TO_IDX(prev_offset - poffset)];
 1350                         for (i = vn_off2bidx(prev_offset);
 1351                             i < sizeof(vm_page_bits_t) * NBBY &&
 1352                             prev_offset < maxblksz; i++) {
 1353                                 if (vn_dirty_blk(m, prev_offset)) {
 1354                                         in_hole = false;
 1355                                         break;
 1356                                 }
 1357                                 prev_offset += DEV_BSIZE;
 1358                         }
 1359                 }
 1360                 if (in_hole)
 1361                         goto write_done;
 1362 
 1363                 /* Find longest run of dirty blocks. */
 1364                 for (next_offset = prev_offset; next_offset < maxblksz;) {
 1365                         m = ma[OFF_TO_IDX(next_offset - poffset)];
 1366                         for (i = vn_off2bidx(next_offset);
 1367                             i < sizeof(vm_page_bits_t) * NBBY &&
 1368                             next_offset < maxblksz; i++) {
 1369                                 if (!vn_dirty_blk(m, next_offset))
 1370                                         goto start_write;
 1371                                 next_offset += DEV_BSIZE;
 1372                         }
 1373                 }
 1374 start_write:
 1375                 if (next_offset > poffset + maxsize)
 1376                         next_offset = poffset + maxsize;
 1377 
 1378                 /*
 1379                  * Getting here requires finding a dirty block in the
 1380                  * 'skip clean blocks' loop.
 1381                  */
 1382                 MPASS(prev_offset < next_offset);
 1383 
 1384                 VM_OBJECT_RUNLOCK(object);
 1385                 aiov.iov_base = NULL;
 1386                 auio.uio_iovcnt = 1;
 1387                 auio.uio_offset = prev_offset;
 1388                 prev_resid = auio.uio_resid = aiov.iov_len = next_offset -
 1389                     prev_offset;
 1390                 error = VOP_WRITE(vp, &auio,
 1391                     vnode_pager_putpages_ioflags(flags), curthread->td_ucred);
 1392 
 1393                 wrsz = prev_resid - auio.uio_resid;
 1394                 if (wrsz == 0) {
 1395                         if (ppsratecheck(&lastfail, &curfail, 1) != 0) {
 1396                                 vn_printf(vp, "vnode_pager_putpages: "
 1397                                     "zero-length write at %ju resid %zd\n",
 1398                                     auio.uio_offset, auio.uio_resid);
 1399                         }
 1400                         VM_OBJECT_RLOCK(object);
 1401                         break;
 1402                 }
 1403 
 1404                 /* Adjust the starting offset for next iteration. */
 1405                 prev_offset += wrsz;
 1406                 MPASS(auio.uio_offset == prev_offset);
 1407 
 1408                 ppscheck = 0;
 1409                 if (error != 0 && (ppscheck = ppsratecheck(&lastfail,
 1410                     &curfail, 1)) != 0)
 1411                         vn_printf(vp, "vnode_pager_putpages: I/O error %d\n",
 1412                             error);
 1413                 if (auio.uio_resid != 0 && (ppscheck != 0 ||
 1414                     ppsratecheck(&lastfail, &curfail, 1) != 0))
 1415                         vn_printf(vp, "vnode_pager_putpages: residual I/O %zd "
 1416                             "at %ju\n", auio.uio_resid,
 1417                             (uintmax_t)ma[0]->pindex);
 1418                 VM_OBJECT_RLOCK(object);
 1419                 if (error != 0 || auio.uio_resid != 0)
 1420                         break;
 1421         }
 1422 write_done:
 1423         /* Mark completely processed pages. */
 1424         for (i = 0; i < OFF_TO_IDX(prev_offset - poffset); i++)
 1425                 rtvals[i] = VM_PAGER_OK;
 1426         /* Mark partial EOF page. */
 1427         if (prev_offset == poffset + maxsize && (prev_offset & PAGE_MASK) != 0)
 1428                 rtvals[i++] = VM_PAGER_OK;
 1429         /* Unwritten pages in range, free bonus if the page is clean. */
 1430         for (; i < ncount; i++)
 1431                 rtvals[i] = ma[i]->dirty == 0 ? VM_PAGER_OK : VM_PAGER_ERROR;
 1432         VM_OBJECT_RUNLOCK(object);
 1433         VM_CNT_ADD(v_vnodepgsout, i);
 1434         VM_CNT_INC(v_vnodeout);
 1435         return (rtvals[0]);
 1436 }
 1437 
 1438 int
 1439 vnode_pager_putpages_ioflags(int pager_flags)
 1440 {
 1441         int ioflags;
 1442 
 1443         /*
 1444          * Pageouts are already clustered, use IO_ASYNC to force a
 1445          * bawrite() rather then a bdwrite() to prevent paging I/O
 1446          * from saturating the buffer cache.  Dummy-up the sequential
 1447          * heuristic to cause large ranges to cluster.  If neither
 1448          * IO_SYNC or IO_ASYNC is set, the system decides how to
 1449          * cluster.
 1450          */
 1451         ioflags = IO_VMIO;
 1452         if ((pager_flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL)) != 0)
 1453                 ioflags |= IO_SYNC;
 1454         else if ((pager_flags & VM_PAGER_CLUSTER_OK) == 0)
 1455                 ioflags |= IO_ASYNC;
 1456         ioflags |= (pager_flags & VM_PAGER_PUT_INVAL) != 0 ? IO_INVAL: 0;
 1457         ioflags |= (pager_flags & VM_PAGER_PUT_NOREUSE) != 0 ? IO_NOREUSE : 0;
 1458         ioflags |= IO_SEQMAX << IO_SEQSHIFT;
 1459         return (ioflags);
 1460 }
 1461 
 1462 /*
 1463  * vnode_pager_undirty_pages().
 1464  *
 1465  * A helper to mark pages as clean after pageout that was possibly
 1466  * done with a short write.  The lpos argument specifies the page run
 1467  * length in bytes, and the written argument specifies how many bytes
 1468  * were actually written.  eof is the offset past the last valid byte
 1469  * in the vnode using the absolute file position of the first byte in
 1470  * the run as the base from which it is computed.
 1471  */
 1472 void
 1473 vnode_pager_undirty_pages(vm_page_t *ma, int *rtvals, int written, off_t eof,
 1474     int lpos)
 1475 {
 1476         vm_object_t obj;
 1477         int i, pos, pos_devb;
 1478 
 1479         if (written == 0 && eof >= lpos)
 1480                 return;
 1481         obj = ma[0]->object;
 1482         VM_OBJECT_WLOCK(obj);
 1483         for (i = 0, pos = 0; pos < written; i++, pos += PAGE_SIZE) {
 1484                 if (pos < trunc_page(written)) {
 1485                         rtvals[i] = VM_PAGER_OK;
 1486                         vm_page_undirty(ma[i]);
 1487                 } else {
 1488                         /* Partially written page. */
 1489                         rtvals[i] = VM_PAGER_AGAIN;
 1490                         vm_page_clear_dirty(ma[i], 0, written & PAGE_MASK);
 1491                 }
 1492         }
 1493         if (eof >= lpos) /* avoid truncation */
 1494                 goto done;
 1495         for (pos = eof, i = OFF_TO_IDX(trunc_page(pos)); pos < lpos; i++) {
 1496                 if (pos != trunc_page(pos)) {
 1497                         /*
 1498                          * The page contains the last valid byte in
 1499                          * the vnode, mark the rest of the page as
 1500                          * clean, potentially making the whole page
 1501                          * clean.
 1502                          */
 1503                         pos_devb = roundup2(pos & PAGE_MASK, DEV_BSIZE);
 1504                         vm_page_clear_dirty(ma[i], pos_devb, PAGE_SIZE -
 1505                             pos_devb);
 1506 
 1507                         /*
 1508                          * If the page was cleaned, report the pageout
 1509                          * on it as successful.  msync() no longer
 1510                          * needs to write out the page, endlessly
 1511                          * creating write requests and dirty buffers.
 1512                          */
 1513                         if (ma[i]->dirty == 0)
 1514                                 rtvals[i] = VM_PAGER_OK;
 1515 
 1516                         pos = round_page(pos);
 1517                 } else {
 1518                         /* vm_pageout_flush() clears dirty */
 1519                         rtvals[i] = VM_PAGER_BAD;
 1520                         pos += PAGE_SIZE;
 1521                 }
 1522         }
 1523 done:
 1524         VM_OBJECT_WUNLOCK(obj);
 1525 }
 1526 
 1527 static void
 1528 vnode_pager_update_writecount(vm_object_t object, vm_offset_t start,
 1529     vm_offset_t end)
 1530 {
 1531         struct vnode *vp;
 1532         vm_ooffset_t old_wm;
 1533 
 1534         VM_OBJECT_WLOCK(object);
 1535         if (object->type != OBJT_VNODE) {
 1536                 VM_OBJECT_WUNLOCK(object);
 1537                 return;
 1538         }
 1539         old_wm = object->un_pager.vnp.writemappings;
 1540         object->un_pager.vnp.writemappings += (vm_ooffset_t)end - start;
 1541         vp = object->handle;
 1542         if (old_wm == 0 && object->un_pager.vnp.writemappings != 0) {
 1543                 ASSERT_VOP_LOCKED(vp, "v_writecount inc");
 1544                 VOP_ADD_WRITECOUNT_CHECKED(vp, 1);
 1545                 CTR3(KTR_VFS, "%s: vp %p v_writecount increased to %d",
 1546                     __func__, vp, vp->v_writecount);
 1547         } else if (old_wm != 0 && object->un_pager.vnp.writemappings == 0) {
 1548                 ASSERT_VOP_LOCKED(vp, "v_writecount dec");
 1549                 VOP_ADD_WRITECOUNT_CHECKED(vp, -1);
 1550                 CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
 1551                     __func__, vp, vp->v_writecount);
 1552         }
 1553         VM_OBJECT_WUNLOCK(object);
 1554 }
 1555 
 1556 static void
 1557 vnode_pager_release_writecount(vm_object_t object, vm_offset_t start,
 1558     vm_offset_t end)
 1559 {
 1560         struct vnode *vp;
 1561         struct mount *mp;
 1562         vm_offset_t inc;
 1563 
 1564         VM_OBJECT_WLOCK(object);
 1565 
 1566         /*
 1567          * First, recheck the object type to account for the race when
 1568          * the vnode is reclaimed.
 1569          */
 1570         if (object->type != OBJT_VNODE) {
 1571                 VM_OBJECT_WUNLOCK(object);
 1572                 return;
 1573         }
 1574 
 1575         /*
 1576          * Optimize for the case when writemappings is not going to
 1577          * zero.
 1578          */
 1579         inc = end - start;
 1580         if (object->un_pager.vnp.writemappings != inc) {
 1581                 object->un_pager.vnp.writemappings -= inc;
 1582                 VM_OBJECT_WUNLOCK(object);
 1583                 return;
 1584         }
 1585 
 1586         vp = object->handle;
 1587         vhold(vp);
 1588         VM_OBJECT_WUNLOCK(object);
 1589         mp = NULL;
 1590         vn_start_write(vp, &mp, V_WAIT);
 1591         vn_lock(vp, LK_SHARED | LK_RETRY);
 1592 
 1593         /*
 1594          * Decrement the object's writemappings, by swapping the start
 1595          * and end arguments for vnode_pager_update_writecount().  If
 1596          * there was not a race with vnode reclaimation, then the
 1597          * vnode's v_writecount is decremented.
 1598          */
 1599         vnode_pager_update_writecount(object, end, start);
 1600         VOP_UNLOCK(vp, 0);
 1601         vdrop(vp);
 1602         if (mp != NULL)
 1603                 vn_finished_write(mp);
 1604 }

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