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  * Copyright (c) 1990 University of Utah.
    3  * Copyright (c) 1991 The Regents of the University of California.
    4  * All rights reserved.
    5  * Copyright (c) 1993, 1994 John S. Dyson
    6  * Copyright (c) 1995, David Greenman
    7  *
    8  * This code is derived from software contributed to Berkeley by
    9  * the Systems Programming Group of the University of Utah Computer
   10  * Science Department.
   11  *
   12  * Redistribution and use in source and binary forms, with or without
   13  * modification, are permitted provided that the following conditions
   14  * are met:
   15  * 1. Redistributions of source code must retain the above copyright
   16  *    notice, this list of conditions and the following disclaimer.
   17  * 2. Redistributions in binary form must reproduce the above copyright
   18  *    notice, this list of conditions and the following disclaimer in the
   19  *    documentation and/or other materials provided with the distribution.
   20  * 3. All advertising materials mentioning features or use of this software
   21  *    must display the following acknowledgement:
   22  *      This product includes software developed by the University of
   23  *      California, Berkeley and its contributors.
   24  * 4. Neither the name of the University nor the names of its contributors
   25  *    may be used to endorse or promote products derived from this software
   26  *    without specific prior written permission.
   27  *
   28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   38  * SUCH DAMAGE.
   39  *
   40  *      from: @(#)vnode_pager.c 7.5 (Berkeley) 4/20/91
   41  */
   42 
   43 /*
   44  * Page to/from files (vnodes).
   45  */
   46 
   47 /*
   48  * TODO:
   49  *      Implement VOP_GETPAGES/PUTPAGES interface for filesystems. Will
   50  *      greatly re-simplify the vnode_pager.
   51  */
   52 
   53 #include <sys/cdefs.h>
   54 __FBSDID("$FreeBSD: src/sys/vm/vnode_pager.c,v 1.192 2003/11/15 09:54:11 tjr Exp $");
   55 
   56 #include <sys/param.h>
   57 #include <sys/systm.h>
   58 #include <sys/proc.h>
   59 #include <sys/vnode.h>
   60 #include <sys/mount.h>
   61 #include <sys/bio.h>
   62 #include <sys/buf.h>
   63 #include <sys/vmmeter.h>
   64 #include <sys/conf.h>
   65 
   66 #include <vm/vm.h>
   67 #include <vm/vm_object.h>
   68 #include <vm/vm_page.h>
   69 #include <vm/vm_pager.h>
   70 #include <vm/vm_map.h>
   71 #include <vm/vnode_pager.h>
   72 #include <vm/vm_extern.h>
   73 
   74 static void vnode_pager_init(void);
   75 static vm_offset_t vnode_pager_addr(struct vnode *vp, vm_ooffset_t address,
   76                                          int *run);
   77 static int vnode_pager_input_smlfs(vm_object_t object, vm_page_t m);
   78 static int vnode_pager_input_old(vm_object_t object, vm_page_t m);
   79 static void vnode_pager_dealloc(vm_object_t);
   80 static int vnode_pager_getpages(vm_object_t, vm_page_t *, int, int);
   81 static void vnode_pager_putpages(vm_object_t, vm_page_t *, int, boolean_t, int *);
   82 static boolean_t vnode_pager_haspage(vm_object_t, vm_pindex_t, int *, int *);
   83 
   84 struct pagerops vnodepagerops = {
   85         .pgo_init =     vnode_pager_init,
   86         .pgo_alloc =    vnode_pager_alloc,
   87         .pgo_dealloc =  vnode_pager_dealloc,
   88         .pgo_getpages = vnode_pager_getpages,
   89         .pgo_putpages = vnode_pager_putpages,
   90         .pgo_haspage =  vnode_pager_haspage,
   91 };
   92 
   93 int vnode_pbuf_freecnt;
   94 
   95 static void
   96 vnode_pager_init(void)
   97 {
   98 
   99         vnode_pbuf_freecnt = nswbuf / 2 + 1;
  100 }
  101 
  102 /*
  103  * Allocate (or lookup) pager for a vnode.
  104  * Handle is a vnode pointer.
  105  *
  106  * MPSAFE
  107  */
  108 vm_object_t
  109 vnode_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
  110                   vm_ooffset_t offset)
  111 {
  112         vm_object_t object;
  113         struct vnode *vp;
  114 
  115         /*
  116          * Pageout to vnode, no can do yet.
  117          */
  118         if (handle == NULL)
  119                 return (NULL);
  120 
  121         vp = (struct vnode *) handle;
  122 
  123         ASSERT_VOP_LOCKED(vp, "vnode_pager_alloc");
  124 
  125         mtx_lock(&Giant);
  126         /*
  127          * Prevent race condition when allocating the object. This
  128          * can happen with NFS vnodes since the nfsnode isn't locked.
  129          */
  130         VI_LOCK(vp);
  131         while (vp->v_iflag & VI_OLOCK) {
  132                 vp->v_iflag |= VI_OWANT;
  133                 msleep(vp, VI_MTX(vp), PVM, "vnpobj", 0);
  134         }
  135         vp->v_iflag |= VI_OLOCK;
  136         VI_UNLOCK(vp);
  137 
  138         /*
  139          * If the object is being terminated, wait for it to
  140          * go away.
  141          */
  142         while ((object = vp->v_object) != NULL) {
  143                 VM_OBJECT_LOCK(object);
  144                 if ((object->flags & OBJ_DEAD) == 0)
  145                         break;
  146                 msleep(object, VM_OBJECT_MTX(object), PDROP | PVM, "vadead", 0);
  147         }
  148 
  149         if (vp->v_usecount == 0)
  150                 panic("vnode_pager_alloc: no vnode reference");
  151 
  152         if (object == NULL) {
  153                 /*
  154                  * And an object of the appropriate size
  155                  */
  156                 object = vm_object_allocate(OBJT_VNODE, OFF_TO_IDX(round_page(size)));
  157 
  158                 object->un_pager.vnp.vnp_size = size;
  159 
  160                 object->handle = handle;
  161                 vp->v_object = object;
  162         } else {
  163                 object->ref_count++;
  164                 VM_OBJECT_UNLOCK(object);
  165         }
  166         VI_LOCK(vp);
  167         vp->v_usecount++;
  168         vp->v_iflag &= ~VI_OLOCK;
  169         if (vp->v_iflag & VI_OWANT) {
  170                 vp->v_iflag &= ~VI_OWANT;
  171                 wakeup(vp);
  172         }
  173         VI_UNLOCK(vp);
  174         mtx_unlock(&Giant);
  175         return (object);
  176 }
  177 
  178 /*
  179  *      The object must be locked.
  180  */
  181 static void
  182 vnode_pager_dealloc(object)
  183         vm_object_t object;
  184 {
  185         struct vnode *vp = object->handle;
  186 
  187         if (vp == NULL)
  188                 panic("vnode_pager_dealloc: pager already dealloced");
  189 
  190         VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
  191         vm_object_pip_wait(object, "vnpdea");
  192 
  193         object->handle = NULL;
  194         object->type = OBJT_DEAD;
  195         ASSERT_VOP_LOCKED(vp, "vnode_pager_dealloc");
  196         vp->v_object = NULL;
  197         vp->v_vflag &= ~(VV_TEXT | VV_OBJBUF);
  198 }
  199 
  200 static boolean_t
  201 vnode_pager_haspage(object, pindex, before, after)
  202         vm_object_t object;
  203         vm_pindex_t pindex;
  204         int *before;
  205         int *after;
  206 {
  207         struct vnode *vp = object->handle;
  208         daddr_t bn;
  209         int err;
  210         daddr_t reqblock;
  211         int poff;
  212         int bsize;
  213         int pagesperblock, blocksperpage;
  214 
  215         VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
  216         /*
  217          * If no vp or vp is doomed or marked transparent to VM, we do not
  218          * have the page.
  219          */
  220         if (vp == NULL)
  221                 return FALSE;
  222 
  223         VI_LOCK(vp);
  224         if (vp->v_iflag & VI_DOOMED) {
  225                 VI_UNLOCK(vp);
  226                 return FALSE;
  227         }
  228         VI_UNLOCK(vp);
  229         /*
  230          * If filesystem no longer mounted or offset beyond end of file we do
  231          * not have the page.
  232          */
  233         if ((vp->v_mount == NULL) ||
  234             (IDX_TO_OFF(pindex) >= object->un_pager.vnp.vnp_size))
  235                 return FALSE;
  236 
  237         bsize = vp->v_mount->mnt_stat.f_iosize;
  238         pagesperblock = bsize / PAGE_SIZE;
  239         blocksperpage = 0;
  240         if (pagesperblock > 0) {
  241                 reqblock = pindex / pagesperblock;
  242         } else {
  243                 blocksperpage = (PAGE_SIZE / bsize);
  244                 reqblock = pindex * blocksperpage;
  245         }
  246         VM_OBJECT_UNLOCK(object);
  247         err = VOP_BMAP(vp, reqblock, NULL, &bn, after, before);
  248         VM_OBJECT_LOCK(object);
  249         if (err)
  250                 return TRUE;
  251         if (bn == -1)
  252                 return FALSE;
  253         if (pagesperblock > 0) {
  254                 poff = pindex - (reqblock * pagesperblock);
  255                 if (before) {
  256                         *before *= pagesperblock;
  257                         *before += poff;
  258                 }
  259                 if (after) {
  260                         int numafter;
  261                         *after *= pagesperblock;
  262                         numafter = pagesperblock - (poff + 1);
  263                         if (IDX_TO_OFF(pindex + numafter) >
  264                             object->un_pager.vnp.vnp_size) {
  265                                 numafter =
  266                                     OFF_TO_IDX(object->un_pager.vnp.vnp_size) -
  267                                     pindex;
  268                         }
  269                         *after += numafter;
  270                 }
  271         } else {
  272                 if (before) {
  273                         *before /= blocksperpage;
  274                 }
  275 
  276                 if (after) {
  277                         *after /= blocksperpage;
  278                 }
  279         }
  280         return TRUE;
  281 }
  282 
  283 /*
  284  * Lets the VM system know about a change in size for a file.
  285  * We adjust our own internal size and flush any cached pages in
  286  * the associated object that are affected by the size change.
  287  *
  288  * Note: this routine may be invoked as a result of a pager put
  289  * operation (possibly at object termination time), so we must be careful.
  290  */
  291 void
  292 vnode_pager_setsize(vp, nsize)
  293         struct vnode *vp;
  294         vm_ooffset_t nsize;
  295 {
  296         vm_object_t object;
  297         vm_page_t m;
  298         vm_pindex_t nobjsize;
  299 
  300         if ((object = vp->v_object) == NULL)
  301                 return;
  302         VM_OBJECT_LOCK(object);
  303         if (nsize == object->un_pager.vnp.vnp_size) {
  304                 /*
  305                  * Hasn't changed size
  306                  */
  307                 VM_OBJECT_UNLOCK(object);
  308                 return;
  309         }
  310         nobjsize = OFF_TO_IDX(nsize + PAGE_MASK);
  311         if (nsize < object->un_pager.vnp.vnp_size) {
  312                 /*
  313                  * File has shrunk. Toss any cached pages beyond the new EOF.
  314                  */
  315                 if (nobjsize < object->size)
  316                         vm_object_page_remove(object, nobjsize, object->size,
  317                             FALSE);
  318                 /*
  319                  * this gets rid of garbage at the end of a page that is now
  320                  * only partially backed by the vnode.
  321                  *
  322                  * XXX for some reason (I don't know yet), if we take a
  323                  * completely invalid page and mark it partially valid
  324                  * it can screw up NFS reads, so we don't allow the case.
  325                  */
  326                 if ((nsize & PAGE_MASK) &&
  327                     (m = vm_page_lookup(object, OFF_TO_IDX(nsize))) != NULL &&
  328                     m->valid != 0) {
  329                         int base = (int)nsize & PAGE_MASK;
  330                         int size = PAGE_SIZE - base;
  331 
  332                         /*
  333                          * Clear out partial-page garbage in case
  334                          * the page has been mapped.
  335                          */
  336                         pmap_zero_page_area(m, base, size);
  337 
  338                         /*
  339                          * XXX work around SMP data integrity race
  340                          * by unmapping the page from user processes.
  341                          * The garbage we just cleared may be mapped
  342                          * to a user process running on another cpu
  343                          * and this code is not running through normal
  344                          * I/O channels which handle SMP issues for
  345                          * us, so unmap page to synchronize all cpus.
  346                          *
  347                          * XXX should vm_pager_unmap_page() have
  348                          * dealt with this?
  349                          */
  350                         vm_page_lock_queues();
  351                         pmap_remove_all(m);
  352 
  353                         /*
  354                          * Clear out partial-page dirty bits.  This
  355                          * has the side effect of setting the valid
  356                          * bits, but that is ok.  There are a bunch
  357                          * of places in the VM system where we expected
  358                          * m->dirty == VM_PAGE_BITS_ALL.  The file EOF
  359                          * case is one of them.  If the page is still
  360                          * partially dirty, make it fully dirty.
  361                          *
  362                          * note that we do not clear out the valid
  363                          * bits.  This would prevent bogus_page
  364                          * replacement from working properly.
  365                          */
  366                         vm_page_set_validclean(m, base, size);
  367                         if (m->dirty != 0)
  368                                 m->dirty = VM_PAGE_BITS_ALL;
  369                         vm_page_unlock_queues();
  370                 }
  371         }
  372         object->un_pager.vnp.vnp_size = nsize;
  373         object->size = nobjsize;
  374         VM_OBJECT_UNLOCK(object);
  375 }
  376 
  377 /*
  378  * calculate the linear (byte) disk address of specified virtual
  379  * file address
  380  */
  381 static vm_offset_t
  382 vnode_pager_addr(vp, address, run)
  383         struct vnode *vp;
  384         vm_ooffset_t address;
  385         int *run;
  386 {
  387         int rtaddress;
  388         int bsize;
  389         daddr_t block;
  390         int err;
  391         daddr_t vblock;
  392         int voffset;
  393 
  394         GIANT_REQUIRED;
  395         if ((int) address < 0)
  396                 return -1;
  397 
  398         if (vp->v_mount == NULL)
  399                 return -1;
  400 
  401         bsize = vp->v_mount->mnt_stat.f_iosize;
  402         vblock = address / bsize;
  403         voffset = address % bsize;
  404 
  405         err = VOP_BMAP(vp, vblock, NULL, &block, run, NULL);
  406 
  407         if (err || (block == -1))
  408                 rtaddress = -1;
  409         else {
  410                 rtaddress = block + voffset / DEV_BSIZE;
  411                 if (run) {
  412                         *run += 1;
  413                         *run *= bsize/PAGE_SIZE;
  414                         *run -= voffset/PAGE_SIZE;
  415                 }
  416         }
  417 
  418         return rtaddress;
  419 }
  420 
  421 /*
  422  * small block filesystem vnode pager input
  423  */
  424 static int
  425 vnode_pager_input_smlfs(object, m)
  426         vm_object_t object;
  427         vm_page_t m;
  428 {
  429         int i;
  430         struct vnode *dp, *vp;
  431         struct buf *bp;
  432         vm_offset_t kva;
  433         int fileaddr;
  434         vm_offset_t bsize;
  435         int error = 0;
  436 
  437         GIANT_REQUIRED;
  438 
  439         vp = object->handle;
  440         if (vp->v_mount == NULL)
  441                 return VM_PAGER_BAD;
  442 
  443         bsize = vp->v_mount->mnt_stat.f_iosize;
  444 
  445         VOP_BMAP(vp, 0, &dp, 0, NULL, NULL);
  446 
  447         kva = vm_pager_map_page(m);
  448 
  449         for (i = 0; i < PAGE_SIZE / bsize; i++) {
  450                 vm_ooffset_t address;
  451 
  452                 if (vm_page_bits(i * bsize, bsize) & m->valid)
  453                         continue;
  454 
  455                 address = IDX_TO_OFF(m->pindex) + i * bsize;
  456                 if (address >= object->un_pager.vnp.vnp_size) {
  457                         fileaddr = -1;
  458                 } else {
  459                         fileaddr = vnode_pager_addr(vp, address, NULL);
  460                 }
  461                 if (fileaddr != -1) {
  462                         bp = getpbuf(&vnode_pbuf_freecnt);
  463 
  464                         /* build a minimal buffer header */
  465                         bp->b_iocmd = BIO_READ;
  466                         bp->b_iodone = bdone;
  467                         KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
  468                         KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
  469                         bp->b_rcred = crhold(curthread->td_ucred);
  470                         bp->b_wcred = crhold(curthread->td_ucred);
  471                         bp->b_data = (caddr_t) kva + i * bsize;
  472                         bp->b_blkno = fileaddr;
  473                         pbgetvp(dp, bp);
  474                         bp->b_bcount = bsize;
  475                         bp->b_bufsize = bsize;
  476                         bp->b_runningbufspace = bp->b_bufsize;
  477                         runningbufspace += bp->b_runningbufspace;
  478 
  479                         /* do the input */
  480                         bp->b_iooffset = dbtob(bp->b_blkno);
  481                         if (dp->v_type == VCHR)
  482                                 VOP_SPECSTRATEGY(bp->b_vp, bp);
  483                         else
  484                                 VOP_STRATEGY(bp->b_vp, bp);
  485 
  486                         /* we definitely need to be at splvm here */
  487 
  488                         bwait(bp, PVM, "vnsrd");
  489 
  490                         if ((bp->b_ioflags & BIO_ERROR) != 0)
  491                                 error = EIO;
  492 
  493                         /*
  494                          * free the buffer header back to the swap buffer pool
  495                          */
  496                         relpbuf(bp, &vnode_pbuf_freecnt);
  497                         if (error)
  498                                 break;
  499 
  500                         VM_OBJECT_LOCK(object);
  501                         vm_page_lock_queues();
  502                         vm_page_set_validclean(m, (i * bsize) & PAGE_MASK, bsize);
  503                         vm_page_unlock_queues();
  504                         VM_OBJECT_UNLOCK(object);
  505                 } else {
  506                         VM_OBJECT_LOCK(object);
  507                         vm_page_lock_queues();
  508                         vm_page_set_validclean(m, (i * bsize) & PAGE_MASK, bsize);
  509                         vm_page_unlock_queues();
  510                         VM_OBJECT_UNLOCK(object);
  511                         bzero((caddr_t) kva + i * bsize, bsize);
  512                 }
  513         }
  514         vm_pager_unmap_page(kva);
  515         vm_page_lock_queues();
  516         pmap_clear_modify(m);
  517         vm_page_flag_clear(m, PG_ZERO);
  518         vm_page_unlock_queues();
  519         if (error) {
  520                 return VM_PAGER_ERROR;
  521         }
  522         return VM_PAGER_OK;
  523 
  524 }
  525 
  526 
  527 /*
  528  * old style vnode pager output routine
  529  */
  530 static int
  531 vnode_pager_input_old(object, m)
  532         vm_object_t object;
  533         vm_page_t m;
  534 {
  535         struct uio auio;
  536         struct iovec aiov;
  537         int error;
  538         int size;
  539         vm_offset_t kva;
  540         struct vnode *vp;
  541 
  542         VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
  543         error = 0;
  544 
  545         /*
  546          * Return failure if beyond current EOF
  547          */
  548         if (IDX_TO_OFF(m->pindex) >= object->un_pager.vnp.vnp_size) {
  549                 return VM_PAGER_BAD;
  550         } else {
  551                 size = PAGE_SIZE;
  552                 if (IDX_TO_OFF(m->pindex) + size > object->un_pager.vnp.vnp_size)
  553                         size = object->un_pager.vnp.vnp_size - IDX_TO_OFF(m->pindex);
  554                 vp = object->handle;
  555                 VM_OBJECT_UNLOCK(object);
  556 
  557                 /*
  558                  * Allocate a kernel virtual address and initialize so that
  559                  * we can use VOP_READ/WRITE routines.
  560                  */
  561                 kva = vm_pager_map_page(m);
  562 
  563                 aiov.iov_base = (caddr_t) kva;
  564                 aiov.iov_len = size;
  565                 auio.uio_iov = &aiov;
  566                 auio.uio_iovcnt = 1;
  567                 auio.uio_offset = IDX_TO_OFF(m->pindex);
  568                 auio.uio_segflg = UIO_SYSSPACE;
  569                 auio.uio_rw = UIO_READ;
  570                 auio.uio_resid = size;
  571                 auio.uio_td = curthread;
  572 
  573                 error = VOP_READ(vp, &auio, 0, curthread->td_ucred);
  574                 if (!error) {
  575                         int count = size - auio.uio_resid;
  576 
  577                         if (count == 0)
  578                                 error = EINVAL;
  579                         else if (count != PAGE_SIZE)
  580                                 bzero((caddr_t) kva + count, PAGE_SIZE - count);
  581                 }
  582                 vm_pager_unmap_page(kva);
  583 
  584                 VM_OBJECT_LOCK(object);
  585         }
  586         vm_page_lock_queues();
  587         pmap_clear_modify(m);
  588         vm_page_undirty(m);
  589         vm_page_flag_clear(m, PG_ZERO);
  590         vm_page_unlock_queues();
  591         if (!error)
  592                 m->valid = VM_PAGE_BITS_ALL;
  593         return error ? VM_PAGER_ERROR : VM_PAGER_OK;
  594 }
  595 
  596 /*
  597  * generic vnode pager input routine
  598  */
  599 
  600 /*
  601  * Local media VFS's that do not implement their own VOP_GETPAGES
  602  * should have their VOP_GETPAGES call to vnode_pager_generic_getpages()
  603  * to implement the previous behaviour.
  604  *
  605  * All other FS's should use the bypass to get to the local media
  606  * backing vp's VOP_GETPAGES.
  607  */
  608 static int
  609 vnode_pager_getpages(object, m, count, reqpage)
  610         vm_object_t object;
  611         vm_page_t *m;
  612         int count;
  613         int reqpage;
  614 {
  615         int rtval;
  616         struct vnode *vp;
  617         int bytes = count * PAGE_SIZE;
  618 
  619         vp = object->handle;
  620         VM_OBJECT_UNLOCK(object);
  621         rtval = VOP_GETPAGES(vp, m, bytes, reqpage, 0);
  622         KASSERT(rtval != EOPNOTSUPP,
  623             ("vnode_pager: FS getpages not implemented\n"));
  624         VM_OBJECT_LOCK(object);
  625         return rtval;
  626 }
  627 
  628 /*
  629  * This is now called from local media FS's to operate against their
  630  * own vnodes if they fail to implement VOP_GETPAGES.
  631  */
  632 int
  633 vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
  634         struct vnode *vp;
  635         vm_page_t *m;
  636         int bytecount;
  637         int reqpage;
  638 {
  639         vm_object_t object;
  640         vm_offset_t kva;
  641         off_t foff, tfoff, nextoff;
  642         int i, j, size, bsize, first, firstaddr;
  643         struct vnode *dp;
  644         int runpg;
  645         int runend;
  646         struct buf *bp;
  647         int count;
  648         int error = 0;
  649 
  650         GIANT_REQUIRED;
  651         object = vp->v_object;
  652         count = bytecount / PAGE_SIZE;
  653 
  654         if (vp->v_mount == NULL)
  655                 return VM_PAGER_BAD;
  656 
  657         bsize = vp->v_mount->mnt_stat.f_iosize;
  658 
  659         /* get the UNDERLYING device for the file with VOP_BMAP() */
  660 
  661         /*
  662          * originally, we did not check for an error return value -- assuming
  663          * an fs always has a bmap entry point -- that assumption is wrong!!!
  664          */
  665         foff = IDX_TO_OFF(m[reqpage]->pindex);
  666 
  667         /*
  668          * if we can't bmap, use old VOP code
  669          */
  670         if (VOP_BMAP(vp, 0, &dp, 0, NULL, NULL)) {
  671                 VM_OBJECT_LOCK(object);
  672                 vm_page_lock_queues();
  673                 for (i = 0; i < count; i++)
  674                         if (i != reqpage)
  675                                 vm_page_free(m[i]);
  676                 vm_page_unlock_queues();
  677                 cnt.v_vnodein++;
  678                 cnt.v_vnodepgsin++;
  679                 error = vnode_pager_input_old(object, m[reqpage]);
  680                 VM_OBJECT_UNLOCK(object);
  681                 return (error);
  682 
  683                 /*
  684                  * if the blocksize is smaller than a page size, then use
  685                  * special small filesystem code.  NFS sometimes has a small
  686                  * blocksize, but it can handle large reads itself.
  687                  */
  688         } else if ((PAGE_SIZE / bsize) > 1 &&
  689             (vp->v_mount->mnt_stat.f_type != nfs_mount_type)) {
  690                 VM_OBJECT_LOCK(object);
  691                 vm_page_lock_queues();
  692                 for (i = 0; i < count; i++)
  693                         if (i != reqpage)
  694                                 vm_page_free(m[i]);
  695                 vm_page_unlock_queues();
  696                 VM_OBJECT_UNLOCK(object);
  697                 cnt.v_vnodein++;
  698                 cnt.v_vnodepgsin++;
  699                 return vnode_pager_input_smlfs(object, m[reqpage]);
  700         }
  701 
  702         /*
  703          * If we have a completely valid page available to us, we can
  704          * clean up and return.  Otherwise we have to re-read the
  705          * media.
  706          */
  707         VM_OBJECT_LOCK(object);
  708         if (m[reqpage]->valid == VM_PAGE_BITS_ALL) {
  709                 vm_page_lock_queues();
  710                 for (i = 0; i < count; i++)
  711                         if (i != reqpage)
  712                                 vm_page_free(m[i]);
  713                 vm_page_unlock_queues();
  714                 VM_OBJECT_UNLOCK(object);
  715                 return VM_PAGER_OK;
  716         }
  717         m[reqpage]->valid = 0;
  718         VM_OBJECT_UNLOCK(object);
  719 
  720         /*
  721          * here on direct device I/O
  722          */
  723         firstaddr = -1;
  724 
  725         /*
  726          * calculate the run that includes the required page
  727          */
  728         for (first = 0, i = 0; i < count; i = runend) {
  729                 firstaddr = vnode_pager_addr(vp,
  730                         IDX_TO_OFF(m[i]->pindex), &runpg);
  731                 if (firstaddr == -1) {
  732                         VM_OBJECT_LOCK(object);
  733                         if (i == reqpage && foff < object->un_pager.vnp.vnp_size) {
  734                                 panic("vnode_pager_getpages: unexpected missing page: firstaddr: %d, foff: 0x%jx%08jx, vnp_size: 0x%jx%08jx",
  735                                     firstaddr, (uintmax_t)(foff >> 32),
  736                                     (uintmax_t)foff,
  737                                     (uintmax_t)
  738                                     (object->un_pager.vnp.vnp_size >> 32),
  739                                     (uintmax_t)object->un_pager.vnp.vnp_size);
  740                         }
  741                         vm_page_lock_queues();
  742                         vm_page_free(m[i]);
  743                         vm_page_unlock_queues();
  744                         VM_OBJECT_UNLOCK(object);
  745                         runend = i + 1;
  746                         first = runend;
  747                         continue;
  748                 }
  749                 runend = i + runpg;
  750                 if (runend <= reqpage) {
  751                         VM_OBJECT_LOCK(object);
  752                         vm_page_lock_queues();
  753                         for (j = i; j < runend; j++)
  754                                 vm_page_free(m[j]);
  755                         vm_page_unlock_queues();
  756                         VM_OBJECT_UNLOCK(object);
  757                 } else {
  758                         if (runpg < (count - first)) {
  759                                 VM_OBJECT_LOCK(object);
  760                                 vm_page_lock_queues();
  761                                 for (i = first + runpg; i < count; i++)
  762                                         vm_page_free(m[i]);
  763                                 vm_page_unlock_queues();
  764                                 VM_OBJECT_UNLOCK(object);
  765                                 count = first + runpg;
  766                         }
  767                         break;
  768                 }
  769                 first = runend;
  770         }
  771 
  772         /*
  773          * the first and last page have been calculated now, move input pages
  774          * to be zero based...
  775          */
  776         if (first != 0) {
  777                 for (i = first; i < count; i++) {
  778                         m[i - first] = m[i];
  779                 }
  780                 count -= first;
  781                 reqpage -= first;
  782         }
  783 
  784         /*
  785          * calculate the file virtual address for the transfer
  786          */
  787         foff = IDX_TO_OFF(m[0]->pindex);
  788 
  789         /*
  790          * calculate the size of the transfer
  791          */
  792         size = count * PAGE_SIZE;
  793         if ((foff + size) > object->un_pager.vnp.vnp_size)
  794                 size = object->un_pager.vnp.vnp_size - foff;
  795 
  796         /*
  797          * round up physical size for real devices.
  798          */
  799         if (dp->v_type == VBLK || dp->v_type == VCHR) {
  800                 int secmask = dp->v_rdev->si_bsize_phys - 1;
  801                 KASSERT(secmask < PAGE_SIZE, ("vnode_pager_generic_getpages: sector size %d too large\n", secmask + 1));
  802                 size = (size + secmask) & ~secmask;
  803         }
  804 
  805         bp = getpbuf(&vnode_pbuf_freecnt);
  806         kva = (vm_offset_t) bp->b_data;
  807 
  808         /*
  809          * and map the pages to be read into the kva
  810          */
  811         pmap_qenter(kva, m, count);
  812 
  813         /* build a minimal buffer header */
  814         bp->b_iocmd = BIO_READ;
  815         bp->b_iodone = bdone;
  816         KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
  817         KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
  818         bp->b_rcred = crhold(curthread->td_ucred);
  819         bp->b_wcred = crhold(curthread->td_ucred);
  820         bp->b_blkno = firstaddr;
  821         pbgetvp(dp, bp);
  822         bp->b_bcount = size;
  823         bp->b_bufsize = size;
  824         bp->b_runningbufspace = bp->b_bufsize;
  825         runningbufspace += bp->b_runningbufspace;
  826 
  827         cnt.v_vnodein++;
  828         cnt.v_vnodepgsin += count;
  829 
  830         /* do the input */
  831         bp->b_iooffset = dbtob(bp->b_blkno);
  832         if (dp->v_type == VCHR)
  833                 VOP_SPECSTRATEGY(bp->b_vp, bp);
  834         else
  835                 VOP_STRATEGY(bp->b_vp, bp);
  836 
  837         bwait(bp, PVM, "vnread");
  838 
  839         if ((bp->b_ioflags & BIO_ERROR) != 0)
  840                 error = EIO;
  841 
  842         if (!error) {
  843                 if (size != count * PAGE_SIZE)
  844                         bzero((caddr_t) kva + size, PAGE_SIZE * count - size);
  845         }
  846         pmap_qremove(kva, count);
  847 
  848         /*
  849          * free the buffer header back to the swap buffer pool
  850          */
  851         relpbuf(bp, &vnode_pbuf_freecnt);
  852 
  853         VM_OBJECT_LOCK(object);
  854         vm_page_lock_queues();
  855         for (i = 0, tfoff = foff; i < count; i++, tfoff = nextoff) {
  856                 vm_page_t mt;
  857 
  858                 nextoff = tfoff + PAGE_SIZE;
  859                 mt = m[i];
  860 
  861                 if (nextoff <= object->un_pager.vnp.vnp_size) {
  862                         /*
  863                          * Read filled up entire page.
  864                          */
  865                         mt->valid = VM_PAGE_BITS_ALL;
  866                         vm_page_undirty(mt);    /* should be an assert? XXX */
  867                         pmap_clear_modify(mt);
  868                 } else {
  869                         /*
  870                          * Read did not fill up entire page.  Since this
  871                          * is getpages, the page may be mapped, so we have
  872                          * to zero the invalid portions of the page even
  873                          * though we aren't setting them valid.
  874                          *
  875                          * Currently we do not set the entire page valid,
  876                          * we just try to clear the piece that we couldn't
  877                          * read.
  878                          */
  879                         vm_page_set_validclean(mt, 0,
  880                             object->un_pager.vnp.vnp_size - tfoff);
  881                         /* handled by vm_fault now */
  882                         /* vm_page_zero_invalid(mt, FALSE); */
  883                 }
  884                 
  885                 vm_page_flag_clear(mt, PG_ZERO);
  886                 if (i != reqpage) {
  887 
  888                         /*
  889                          * whether or not to leave the page activated is up in
  890                          * the air, but we should put the page on a page queue
  891                          * somewhere. (it already is in the object). Result:
  892                          * It appears that empirical results show that
  893                          * deactivating pages is best.
  894                          */
  895 
  896                         /*
  897                          * just in case someone was asking for this page we
  898                          * now tell them that it is ok to use
  899                          */
  900                         if (!error) {
  901                                 if (mt->flags & PG_WANTED)
  902                                         vm_page_activate(mt);
  903                                 else
  904                                         vm_page_deactivate(mt);
  905                                 vm_page_wakeup(mt);
  906                         } else {
  907                                 vm_page_free(mt);
  908                         }
  909                 }
  910         }
  911         vm_page_unlock_queues();
  912         VM_OBJECT_UNLOCK(object);
  913         if (error) {
  914                 printf("vnode_pager_getpages: I/O read error\n");
  915         }
  916         return (error ? VM_PAGER_ERROR : VM_PAGER_OK);
  917 }
  918 
  919 /*
  920  * EOPNOTSUPP is no longer legal.  For local media VFS's that do not
  921  * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to
  922  * vnode_pager_generic_putpages() to implement the previous behaviour.
  923  *
  924  * All other FS's should use the bypass to get to the local media
  925  * backing vp's VOP_PUTPAGES.
  926  */
  927 static void
  928 vnode_pager_putpages(object, m, count, sync, rtvals)
  929         vm_object_t object;
  930         vm_page_t *m;
  931         int count;
  932         boolean_t sync;
  933         int *rtvals;
  934 {
  935         int rtval;
  936         struct vnode *vp;
  937         struct mount *mp;
  938         int bytes = count * PAGE_SIZE;
  939 
  940         GIANT_REQUIRED;
  941         /*
  942          * Force synchronous operation if we are extremely low on memory
  943          * to prevent a low-memory deadlock.  VOP operations often need to
  944          * allocate more memory to initiate the I/O ( i.e. do a BMAP 
  945          * operation ).  The swapper handles the case by limiting the amount
  946          * of asynchronous I/O, but that sort of solution doesn't scale well
  947          * for the vnode pager without a lot of work.
  948          *
  949          * Also, the backing vnode's iodone routine may not wake the pageout
  950          * daemon up.  This should be probably be addressed XXX.
  951          */
  952 
  953         if ((cnt.v_free_count + cnt.v_cache_count) < cnt.v_pageout_free_min)
  954                 sync |= OBJPC_SYNC;
  955 
  956         /*
  957          * Call device-specific putpages function
  958          */
  959         vp = object->handle;
  960         VM_OBJECT_UNLOCK(object);
  961         if (vp->v_type != VREG)
  962                 mp = NULL;
  963         (void)vn_start_write(vp, &mp, V_WAIT);
  964         rtval = VOP_PUTPAGES(vp, m, bytes, sync, rtvals, 0);
  965         KASSERT(rtval != EOPNOTSUPP, 
  966             ("vnode_pager: stale FS putpages\n"));
  967         vn_finished_write(mp);
  968         VM_OBJECT_LOCK(object);
  969 }
  970 
  971 
  972 /*
  973  * This is now called from local media FS's to operate against their
  974  * own vnodes if they fail to implement VOP_PUTPAGES.
  975  *
  976  * This is typically called indirectly via the pageout daemon and
  977  * clustering has already typically occured, so in general we ask the
  978  * underlying filesystem to write the data out asynchronously rather
  979  * then delayed.
  980  */
  981 int
  982 vnode_pager_generic_putpages(vp, m, bytecount, flags, rtvals)
  983         struct vnode *vp;
  984         vm_page_t *m;
  985         int bytecount;
  986         int flags;
  987         int *rtvals;
  988 {
  989         int i;
  990         vm_object_t object;
  991         int count;
  992 
  993         int maxsize, ncount;
  994         vm_ooffset_t poffset;
  995         struct uio auio;
  996         struct iovec aiov;
  997         int error;
  998         int ioflags;
  999 
 1000         GIANT_REQUIRED;
 1001         object = vp->v_object;
 1002         count = bytecount / PAGE_SIZE;
 1003 
 1004         for (i = 0; i < count; i++)
 1005                 rtvals[i] = VM_PAGER_AGAIN;
 1006 
 1007         if ((int) m[0]->pindex < 0) {
 1008                 printf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%lx(%lx)\n",
 1009                         (long)m[0]->pindex, (u_long)m[0]->dirty);
 1010                 rtvals[0] = VM_PAGER_BAD;
 1011                 return VM_PAGER_BAD;
 1012         }
 1013 
 1014         maxsize = count * PAGE_SIZE;
 1015         ncount = count;
 1016 
 1017         poffset = IDX_TO_OFF(m[0]->pindex);
 1018 
 1019         /*
 1020          * If the page-aligned write is larger then the actual file we
 1021          * have to invalidate pages occuring beyond the file EOF.  However,
 1022          * there is an edge case where a file may not be page-aligned where
 1023          * the last page is partially invalid.  In this case the filesystem
 1024          * may not properly clear the dirty bits for the entire page (which
 1025          * could be VM_PAGE_BITS_ALL due to the page having been mmap()d).
 1026          * With the page locked we are free to fix-up the dirty bits here.
 1027          *
 1028          * We do not under any circumstances truncate the valid bits, as
 1029          * this will screw up bogus page replacement.
 1030          */
 1031         if (maxsize + poffset > object->un_pager.vnp.vnp_size) {
 1032                 if (object->un_pager.vnp.vnp_size > poffset) {
 1033                         int pgoff;
 1034 
 1035                         maxsize = object->un_pager.vnp.vnp_size - poffset;
 1036                         ncount = btoc(maxsize);
 1037                         if ((pgoff = (int)maxsize & PAGE_MASK) != 0) {
 1038                                 vm_page_lock_queues();
 1039                                 vm_page_clear_dirty(m[ncount - 1], pgoff,
 1040                                         PAGE_SIZE - pgoff);
 1041                                 vm_page_unlock_queues();
 1042                         }
 1043                 } else {
 1044                         maxsize = 0;
 1045                         ncount = 0;
 1046                 }
 1047                 if (ncount < count) {
 1048                         for (i = ncount; i < count; i++) {
 1049                                 rtvals[i] = VM_PAGER_BAD;
 1050                         }
 1051                 }
 1052         }
 1053 
 1054         /*
 1055          * pageouts are already clustered, use IO_ASYNC t o force a bawrite()
 1056          * rather then a bdwrite() to prevent paging I/O from saturating 
 1057          * the buffer cache.  Dummy-up the sequential heuristic to cause
 1058          * large ranges to cluster.  If neither IO_SYNC or IO_ASYNC is set,
 1059          * the system decides how to cluster.
 1060          */
 1061         ioflags = IO_VMIO;
 1062         if (flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL))
 1063                 ioflags |= IO_SYNC;
 1064         else if ((flags & VM_PAGER_CLUSTER_OK) == 0)
 1065                 ioflags |= IO_ASYNC;
 1066         ioflags |= (flags & VM_PAGER_PUT_INVAL) ? IO_INVAL: 0;
 1067         ioflags |= IO_SEQMAX << IO_SEQSHIFT;
 1068 
 1069         aiov.iov_base = (caddr_t) 0;
 1070         aiov.iov_len = maxsize;
 1071         auio.uio_iov = &aiov;
 1072         auio.uio_iovcnt = 1;
 1073         auio.uio_offset = poffset;
 1074         auio.uio_segflg = UIO_NOCOPY;
 1075         auio.uio_rw = UIO_WRITE;
 1076         auio.uio_resid = maxsize;
 1077         auio.uio_td = (struct thread *) 0;
 1078         error = VOP_WRITE(vp, &auio, ioflags, curthread->td_ucred);
 1079         cnt.v_vnodeout++;
 1080         cnt.v_vnodepgsout += ncount;
 1081 
 1082         if (error) {
 1083                 printf("vnode_pager_putpages: I/O error %d\n", error);
 1084         }
 1085         if (auio.uio_resid) {
 1086                 printf("vnode_pager_putpages: residual I/O %d at %lu\n",
 1087                     auio.uio_resid, (u_long)m[0]->pindex);
 1088         }
 1089         for (i = 0; i < ncount; i++) {
 1090                 rtvals[i] = VM_PAGER_OK;
 1091         }
 1092         return rtvals[0];
 1093 }
 1094 
 1095 struct vnode *
 1096 vnode_pager_lock(vm_object_t first_object)
 1097 {
 1098         struct vnode *vp;
 1099         vm_object_t backing_object, object;
 1100 
 1101         VM_OBJECT_LOCK_ASSERT(first_object, MA_OWNED);
 1102         for (object = first_object; object != NULL; object = backing_object) {
 1103                 if (object->type != OBJT_VNODE) {
 1104                         if ((backing_object = object->backing_object) != NULL)
 1105                                 VM_OBJECT_LOCK(backing_object);
 1106                         if (object != first_object)
 1107                                 VM_OBJECT_UNLOCK(object);
 1108                         continue;
 1109                 }
 1110         retry:
 1111                 if (object->flags & OBJ_DEAD) {
 1112                         if (object != first_object)
 1113                                 VM_OBJECT_UNLOCK(object);
 1114                         return NULL;
 1115                 }
 1116                 vp = object->handle;
 1117                 VI_LOCK(vp);
 1118                 VM_OBJECT_UNLOCK(object);
 1119                 if (first_object != object)
 1120                         VM_OBJECT_UNLOCK(first_object);
 1121                 if (vget(vp, LK_CANRECURSE | LK_INTERLOCK | LK_NOPAUSE |
 1122                     LK_RETRY | LK_SHARED, curthread)) {
 1123                         VM_OBJECT_LOCK(first_object);
 1124                         if (object != first_object)
 1125                                 VM_OBJECT_LOCK(object);
 1126                         if (object->type != OBJT_VNODE) {
 1127                                 if (object != first_object)
 1128                                         VM_OBJECT_UNLOCK(object);
 1129                                 return NULL;
 1130                         }
 1131                         printf("vnode_pager_lock: retrying\n");
 1132                         goto retry;
 1133                 }
 1134                 VM_OBJECT_LOCK(first_object);
 1135                 return (vp);
 1136         }
 1137         return NULL;
 1138 }

Cache object: 26b93252fb592fdd5422336cd5464786


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