The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/nfsclient/nfs_bio.c

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    1 /*-
    2  * Copyright (c) 1989, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * This code is derived from software contributed to Berkeley by
    6  * Rick Macklem at The University of Guelph.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 4. Neither the name of the University nor the names of its contributors
   17  *    may be used to endorse or promote products derived from this software
   18  *    without specific prior written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  *
   32  *      @(#)nfs_bio.c   8.9 (Berkeley) 3/30/95
   33  */
   34 
   35 #include <sys/cdefs.h>
   36 __FBSDID("$FreeBSD: releng/6.0/sys/nfsclient/nfs_bio.c 147420 2005-06-16 15:43:17Z green $");
   37 
   38 #include <sys/param.h>
   39 #include <sys/systm.h>
   40 #include <sys/bio.h>
   41 #include <sys/buf.h>
   42 #include <sys/kernel.h>
   43 #include <sys/mount.h>
   44 #include <sys/proc.h>
   45 #include <sys/resourcevar.h>
   46 #include <sys/signalvar.h>
   47 #include <sys/vmmeter.h>
   48 #include <sys/vnode.h>
   49 
   50 #include <vm/vm.h>
   51 #include <vm/vm_extern.h>
   52 #include <vm/vm_page.h>
   53 #include <vm/vm_object.h>
   54 #include <vm/vm_pager.h>
   55 #include <vm/vnode_pager.h>
   56 
   57 #include <rpc/rpcclnt.h>
   58 
   59 #include <nfs/rpcv2.h>
   60 #include <nfs/nfsproto.h>
   61 #include <nfsclient/nfs.h>
   62 #include <nfsclient/nfsmount.h>
   63 #include <nfsclient/nfsnode.h>
   64 
   65 #include <nfs4client/nfs4.h>
   66 
   67 static struct buf *nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size,
   68                     struct thread *td);
   69 static int nfs_directio_write(struct vnode *vp, struct uio *uiop, 
   70                               struct ucred *cred, int ioflag);
   71 
   72 extern int nfs_directio_enable;
   73 extern int nfs_directio_allow_mmap;
   74 /*
   75  * Vnode op for VM getpages.
   76  */
   77 int
   78 nfs_getpages(struct vop_getpages_args *ap)
   79 {
   80         int i, error, nextoff, size, toff, count, npages;
   81         struct uio uio;
   82         struct iovec iov;
   83         vm_offset_t kva;
   84         struct buf *bp;
   85         struct vnode *vp;
   86         struct thread *td;
   87         struct ucred *cred;
   88         struct nfsmount *nmp;
   89         vm_object_t object;
   90         vm_page_t *pages;
   91         struct nfsnode *np;
   92 
   93         GIANT_REQUIRED;
   94 
   95         vp = ap->a_vp;
   96         np = VTONFS(vp);
   97         td = curthread;                         /* XXX */
   98         cred = curthread->td_ucred;             /* XXX */
   99         nmp = VFSTONFS(vp->v_mount);
  100         pages = ap->a_m;
  101         count = ap->a_count;
  102 
  103         if ((object = vp->v_object) == NULL) {
  104                 printf("nfs_getpages: called with non-merged cache vnode??\n");
  105                 return VM_PAGER_ERROR;
  106         }
  107 
  108         if (!nfs_directio_allow_mmap && (np->n_flag & NNONCACHE) && 
  109             (vp->v_type == VREG)) {
  110                 printf("nfs_getpages: called on non-cacheable vnode??\n");
  111                 return VM_PAGER_ERROR;
  112         }
  113 
  114         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  115             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  116                 /* We'll never get here for v4, because we always have fsinfo */
  117                 (void)nfs_fsinfo(nmp, vp, cred, td);
  118         }
  119 
  120         npages = btoc(count);
  121 
  122         /*
  123          * If the requested page is partially valid, just return it and
  124          * allow the pager to zero-out the blanks.  Partially valid pages
  125          * can only occur at the file EOF.
  126          */
  127 
  128         {
  129                 vm_page_t m = pages[ap->a_reqpage];
  130 
  131                 VM_OBJECT_LOCK(object);
  132                 vm_page_lock_queues();
  133                 if (m->valid != 0) {
  134                         /* handled by vm_fault now        */
  135                         /* vm_page_zero_invalid(m, TRUE); */
  136                         for (i = 0; i < npages; ++i) {
  137                                 if (i != ap->a_reqpage)
  138                                         vm_page_free(pages[i]);
  139                         }
  140                         vm_page_unlock_queues();
  141                         VM_OBJECT_UNLOCK(object);
  142                         return(0);
  143                 }
  144                 vm_page_unlock_queues();
  145                 VM_OBJECT_UNLOCK(object);
  146         }
  147 
  148         /*
  149          * We use only the kva address for the buffer, but this is extremely
  150          * convienient and fast.
  151          */
  152         bp = getpbuf(&nfs_pbuf_freecnt);
  153 
  154         kva = (vm_offset_t) bp->b_data;
  155         pmap_qenter(kva, pages, npages);
  156         cnt.v_vnodein++;
  157         cnt.v_vnodepgsin += npages;
  158 
  159         iov.iov_base = (caddr_t) kva;
  160         iov.iov_len = count;
  161         uio.uio_iov = &iov;
  162         uio.uio_iovcnt = 1;
  163         uio.uio_offset = IDX_TO_OFF(pages[0]->pindex);
  164         uio.uio_resid = count;
  165         uio.uio_segflg = UIO_SYSSPACE;
  166         uio.uio_rw = UIO_READ;
  167         uio.uio_td = td;
  168 
  169         error = (nmp->nm_rpcops->nr_readrpc)(vp, &uio, cred);
  170         pmap_qremove(kva, npages);
  171 
  172         relpbuf(bp, &nfs_pbuf_freecnt);
  173 
  174         if (error && (uio.uio_resid == count)) {
  175                 printf("nfs_getpages: error %d\n", error);
  176                 VM_OBJECT_LOCK(object);
  177                 vm_page_lock_queues();
  178                 for (i = 0; i < npages; ++i) {
  179                         if (i != ap->a_reqpage)
  180                                 vm_page_free(pages[i]);
  181                 }
  182                 vm_page_unlock_queues();
  183                 VM_OBJECT_UNLOCK(object);
  184                 return VM_PAGER_ERROR;
  185         }
  186 
  187         /*
  188          * Calculate the number of bytes read and validate only that number
  189          * of bytes.  Note that due to pending writes, size may be 0.  This
  190          * does not mean that the remaining data is invalid!
  191          */
  192 
  193         size = count - uio.uio_resid;
  194         VM_OBJECT_LOCK(object);
  195         vm_page_lock_queues();
  196         for (i = 0, toff = 0; i < npages; i++, toff = nextoff) {
  197                 vm_page_t m;
  198                 nextoff = toff + PAGE_SIZE;
  199                 m = pages[i];
  200 
  201                 if (nextoff <= size) {
  202                         /*
  203                          * Read operation filled an entire page
  204                          */
  205                         m->valid = VM_PAGE_BITS_ALL;
  206                         vm_page_undirty(m);
  207                 } else if (size > toff) {
  208                         /*
  209                          * Read operation filled a partial page.
  210                          */
  211                         m->valid = 0;
  212                         vm_page_set_validclean(m, 0, size - toff);
  213                         /* handled by vm_fault now        */
  214                         /* vm_page_zero_invalid(m, TRUE); */
  215                 } else {
  216                         /*
  217                          * Read operation was short.  If no error occured
  218                          * we may have hit a zero-fill section.   We simply
  219                          * leave valid set to 0.
  220                          */
  221                         ;
  222                 }
  223                 if (i != ap->a_reqpage) {
  224                         /*
  225                          * Whether or not to leave the page activated is up in
  226                          * the air, but we should put the page on a page queue
  227                          * somewhere (it already is in the object).  Result:
  228                          * It appears that emperical results show that
  229                          * deactivating pages is best.
  230                          */
  231 
  232                         /*
  233                          * Just in case someone was asking for this page we
  234                          * now tell them that it is ok to use.
  235                          */
  236                         if (!error) {
  237                                 if (m->flags & PG_WANTED)
  238                                         vm_page_activate(m);
  239                                 else
  240                                         vm_page_deactivate(m);
  241                                 vm_page_wakeup(m);
  242                         } else {
  243                                 vm_page_free(m);
  244                         }
  245                 }
  246         }
  247         vm_page_unlock_queues();
  248         VM_OBJECT_UNLOCK(object);
  249         return 0;
  250 }
  251 
  252 /*
  253  * Vnode op for VM putpages.
  254  */
  255 int
  256 nfs_putpages(struct vop_putpages_args *ap)
  257 {
  258         struct uio uio;
  259         struct iovec iov;
  260         vm_offset_t kva;
  261         struct buf *bp;
  262         int iomode, must_commit, i, error, npages, count;
  263         off_t offset;
  264         int *rtvals;
  265         struct vnode *vp;
  266         struct thread *td;
  267         struct ucred *cred;
  268         struct nfsmount *nmp;
  269         struct nfsnode *np;
  270         vm_page_t *pages;
  271 
  272         GIANT_REQUIRED;
  273 
  274         vp = ap->a_vp;
  275         np = VTONFS(vp);
  276         td = curthread;                         /* XXX */
  277         cred = curthread->td_ucred;             /* XXX */
  278         nmp = VFSTONFS(vp->v_mount);
  279         pages = ap->a_m;
  280         count = ap->a_count;
  281         rtvals = ap->a_rtvals;
  282         npages = btoc(count);
  283         offset = IDX_TO_OFF(pages[0]->pindex);
  284 
  285         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  286             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  287                 (void)nfs_fsinfo(nmp, vp, cred, td);
  288         }
  289 
  290         if (!nfs_directio_allow_mmap && (np->n_flag & NNONCACHE) && 
  291             (vp->v_type == VREG))
  292                 printf("nfs_putpages: called on noncache-able vnode??\n");
  293 
  294         for (i = 0; i < npages; i++)
  295                 rtvals[i] = VM_PAGER_AGAIN;
  296 
  297         /*
  298          * When putting pages, do not extend file past EOF.
  299          */
  300 
  301         if (offset + count > np->n_size) {
  302                 count = np->n_size - offset;
  303                 if (count < 0)
  304                         count = 0;
  305         }
  306 
  307         /*
  308          * We use only the kva address for the buffer, but this is extremely
  309          * convienient and fast.
  310          */
  311         bp = getpbuf(&nfs_pbuf_freecnt);
  312 
  313         kva = (vm_offset_t) bp->b_data;
  314         pmap_qenter(kva, pages, npages);
  315         cnt.v_vnodeout++;
  316         cnt.v_vnodepgsout += count;
  317 
  318         iov.iov_base = (caddr_t) kva;
  319         iov.iov_len = count;
  320         uio.uio_iov = &iov;
  321         uio.uio_iovcnt = 1;
  322         uio.uio_offset = offset;
  323         uio.uio_resid = count;
  324         uio.uio_segflg = UIO_SYSSPACE;
  325         uio.uio_rw = UIO_WRITE;
  326         uio.uio_td = td;
  327 
  328         if ((ap->a_sync & VM_PAGER_PUT_SYNC) == 0)
  329             iomode = NFSV3WRITE_UNSTABLE;
  330         else
  331             iomode = NFSV3WRITE_FILESYNC;
  332 
  333         error = (nmp->nm_rpcops->nr_writerpc)(vp, &uio, cred, &iomode, &must_commit);
  334 
  335         pmap_qremove(kva, npages);
  336         relpbuf(bp, &nfs_pbuf_freecnt);
  337 
  338         if (!error) {
  339                 int nwritten = round_page(count - uio.uio_resid) / PAGE_SIZE;
  340                 for (i = 0; i < nwritten; i++) {
  341                         rtvals[i] = VM_PAGER_OK;
  342                         vm_page_undirty(pages[i]);
  343                 }
  344                 if (must_commit) {
  345                         nfs_clearcommit(vp->v_mount);
  346                 }
  347         }
  348         return rtvals[0];
  349 }
  350 
  351 /*
  352  * Vnode op for read using bio
  353  */
  354 int
  355 nfs_bioread(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred)
  356 {
  357         struct nfsnode *np = VTONFS(vp);
  358         int biosize, i;
  359         struct buf *bp, *rabp;
  360         struct vattr vattr;
  361         struct thread *td;
  362         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  363         daddr_t lbn, rabn;
  364         int bcount;
  365         int seqcount;
  366         int nra, error = 0, n = 0, on = 0;
  367 
  368 #ifdef DIAGNOSTIC
  369         if (uio->uio_rw != UIO_READ)
  370                 panic("nfs_read mode");
  371 #endif
  372         if (uio->uio_resid == 0)
  373                 return (0);
  374         if (uio->uio_offset < 0)        /* XXX VDIR cookies can be negative */
  375                 return (EINVAL);
  376         td = uio->uio_td;
  377 
  378         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  379             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0)
  380                 (void)nfs_fsinfo(nmp, vp, cred, td);
  381         if (vp->v_type != VDIR &&
  382             (uio->uio_offset + uio->uio_resid) > nmp->nm_maxfilesize)
  383                 return (EFBIG);
  384 
  385         if (nfs_directio_enable && (ioflag & IO_DIRECT) && (vp->v_type == VREG))
  386                 /* No caching/ no readaheads. Just read data into the user buffer */
  387                 return nfs_readrpc(vp, uio, cred);
  388 
  389         biosize = vp->v_mount->mnt_stat.f_iosize;
  390         seqcount = (int)((off_t)(ioflag >> IO_SEQSHIFT) * biosize / BKVASIZE);
  391         /*
  392          * For nfs, cache consistency can only be maintained approximately.
  393          * Although RFC1094 does not specify the criteria, the following is
  394          * believed to be compatible with the reference port.
  395          * For nfs:
  396          * If the file's modify time on the server has changed since the
  397          * last read rpc or you have written to the file,
  398          * you may have lost data cache consistency with the
  399          * server, so flush all of the file's data out of the cache.
  400          * Then force a getattr rpc to ensure that you have up to date
  401          * attributes.
  402          * NB: This implies that cache data can be read when up to
  403          * NFS_ATTRTIMEO seconds out of date. If you find that you need current
  404          * attributes this could be forced by setting n_attrstamp to 0 before
  405          * the VOP_GETATTR() call.
  406          */
  407         if (np->n_flag & NMODIFIED) {
  408                 if (vp->v_type != VREG) {
  409                         if (vp->v_type != VDIR)
  410                                 panic("nfs: bioread, not dir");
  411                         (nmp->nm_rpcops->nr_invaldir)(vp);
  412                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  413                         if (error)
  414                                 return (error);
  415                 }
  416                 np->n_attrstamp = 0;
  417                 error = VOP_GETATTR(vp, &vattr, cred, td);
  418                 if (error)
  419                         return (error);
  420                 np->n_mtime = vattr.va_mtime;
  421         } else {
  422                 error = VOP_GETATTR(vp, &vattr, cred, td);
  423                 if (error)
  424                         return (error);
  425                 if ((np->n_flag & NSIZECHANGED)
  426                     || (NFS_TIMESPEC_COMPARE(&np->n_mtime, &vattr.va_mtime))) {
  427                         if (vp->v_type == VDIR)
  428                                 (nmp->nm_rpcops->nr_invaldir)(vp);
  429                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  430                         if (error)
  431                                 return (error);
  432                         np->n_mtime = vattr.va_mtime;
  433                         np->n_flag &= ~NSIZECHANGED;
  434                 }
  435         }
  436         do {
  437             switch (vp->v_type) {
  438             case VREG:
  439                 nfsstats.biocache_reads++;
  440                 lbn = uio->uio_offset / biosize;
  441                 on = uio->uio_offset & (biosize - 1);
  442 
  443                 /*
  444                  * Start the read ahead(s), as required.
  445                  * The readahead is kicked off only if sequential access
  446                  * is detected, based on the readahead hint (ra_expect_lbn).
  447                  */
  448                 if (nmp->nm_readahead > 0 && np->ra_expect_lbn == lbn) {
  449                     for (nra = 0; nra < nmp->nm_readahead && nra < seqcount &&
  450                         (off_t)(lbn + 1 + nra) * biosize < np->n_size; nra++) {
  451                         rabn = lbn + 1 + nra;
  452                         if (incore(&vp->v_bufobj, rabn) == NULL) {
  453                             rabp = nfs_getcacheblk(vp, rabn, biosize, td);
  454                             if (!rabp) {
  455                                 error = nfs_sigintr(nmp, NULL, td);
  456                                 return (error ? error : EINTR);
  457                             }
  458                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  459                                 rabp->b_flags |= B_ASYNC;
  460                                 rabp->b_iocmd = BIO_READ;
  461                                 vfs_busy_pages(rabp, 0);
  462                                 if (nfs_asyncio(nmp, rabp, cred, td)) {
  463                                     rabp->b_flags |= B_INVAL;
  464                                     rabp->b_ioflags |= BIO_ERROR;
  465                                     vfs_unbusy_pages(rabp);
  466                                     brelse(rabp);
  467                                     break;
  468                                 }
  469                             } else {
  470                                 brelse(rabp);
  471                             }
  472                         }
  473                     }
  474                     np->ra_expect_lbn = lbn + 1;
  475                 }
  476 
  477                 /*
  478                  * Obtain the buffer cache block.  Figure out the buffer size
  479                  * when we are at EOF.  If we are modifying the size of the
  480                  * buffer based on an EOF condition we need to hold
  481                  * nfs_rslock() through obtaining the buffer to prevent
  482                  * a potential writer-appender from messing with n_size.
  483                  * Otherwise we may accidently truncate the buffer and
  484                  * lose dirty data.
  485                  *
  486                  * Note that bcount is *not* DEV_BSIZE aligned.
  487                  */
  488 
  489 again:
  490                 bcount = biosize;
  491                 if ((off_t)lbn * biosize >= np->n_size) {
  492                         bcount = 0;
  493                 } else if ((off_t)(lbn + 1) * biosize > np->n_size) {
  494                         bcount = np->n_size - (off_t)lbn * biosize;
  495                 }
  496                 if (bcount != biosize) {
  497                         switch(nfs_rslock(np, td)) {
  498                         case ENOLCK:
  499                                 goto again;
  500                                 /* not reached */
  501                         case EIO:
  502                                 return (EIO);
  503                         case EINTR:
  504                         case ERESTART:
  505                                 return(EINTR);
  506                                 /* not reached */
  507                         default:
  508                                 break;
  509                         }
  510                 }
  511 
  512                 bp = nfs_getcacheblk(vp, lbn, bcount, td);
  513 
  514                 if (bcount != biosize)
  515                         nfs_rsunlock(np, td);
  516                 if (!bp) {
  517                         error = nfs_sigintr(nmp, NULL, td);
  518                         return (error ? error : EINTR);
  519                 }
  520 
  521                 /*
  522                  * If B_CACHE is not set, we must issue the read.  If this
  523                  * fails, we return an error.
  524                  */
  525 
  526                 if ((bp->b_flags & B_CACHE) == 0) {
  527                     bp->b_iocmd = BIO_READ;
  528                     vfs_busy_pages(bp, 0);
  529                     error = nfs_doio(vp, bp, cred, td);
  530                     if (error) {
  531                         brelse(bp);
  532                         return (error);
  533                     }
  534                 }
  535 
  536                 /*
  537                  * on is the offset into the current bp.  Figure out how many
  538                  * bytes we can copy out of the bp.  Note that bcount is
  539                  * NOT DEV_BSIZE aligned.
  540                  *
  541                  * Then figure out how many bytes we can copy into the uio.
  542                  */
  543 
  544                 n = 0;
  545                 if (on < bcount)
  546                         n = min((unsigned)(bcount - on), uio->uio_resid);
  547                 break;
  548             case VLNK:
  549                 nfsstats.biocache_readlinks++;
  550                 bp = nfs_getcacheblk(vp, (daddr_t)0, NFS_MAXPATHLEN, td);
  551                 if (!bp) {
  552                         error = nfs_sigintr(nmp, NULL, td);
  553                         return (error ? error : EINTR);
  554                 }
  555                 if ((bp->b_flags & B_CACHE) == 0) {
  556                     bp->b_iocmd = BIO_READ;
  557                     vfs_busy_pages(bp, 0);
  558                     error = nfs_doio(vp, bp, cred, td);
  559                     if (error) {
  560                         bp->b_ioflags |= BIO_ERROR;
  561                         brelse(bp);
  562                         return (error);
  563                     }
  564                 }
  565                 n = min(uio->uio_resid, NFS_MAXPATHLEN - bp->b_resid);
  566                 on = 0;
  567                 break;
  568             case VDIR:
  569                 nfsstats.biocache_readdirs++;
  570                 if (np->n_direofoffset
  571                     && uio->uio_offset >= np->n_direofoffset) {
  572                     return (0);
  573                 }
  574                 lbn = (uoff_t)uio->uio_offset / NFS_DIRBLKSIZ;
  575                 on = uio->uio_offset & (NFS_DIRBLKSIZ - 1);
  576                 bp = nfs_getcacheblk(vp, lbn, NFS_DIRBLKSIZ, td);
  577                 if (!bp) {
  578                     error = nfs_sigintr(nmp, NULL, td);
  579                     return (error ? error : EINTR);
  580                 }
  581                 if ((bp->b_flags & B_CACHE) == 0) {
  582                     bp->b_iocmd = BIO_READ;
  583                     vfs_busy_pages(bp, 0);
  584                     error = nfs_doio(vp, bp, cred, td);
  585                     if (error) {
  586                             brelse(bp);
  587                     }
  588                     while (error == NFSERR_BAD_COOKIE) {
  589                         (nmp->nm_rpcops->nr_invaldir)(vp);
  590                         error = nfs_vinvalbuf(vp, 0, td, 1);
  591                         /*
  592                          * Yuck! The directory has been modified on the
  593                          * server. The only way to get the block is by
  594                          * reading from the beginning to get all the
  595                          * offset cookies.
  596                          *
  597                          * Leave the last bp intact unless there is an error.
  598                          * Loop back up to the while if the error is another
  599                          * NFSERR_BAD_COOKIE (double yuch!).
  600                          */
  601                         for (i = 0; i <= lbn && !error; i++) {
  602                             if (np->n_direofoffset
  603                                 && (i * NFS_DIRBLKSIZ) >= np->n_direofoffset)
  604                                     return (0);
  605                             bp = nfs_getcacheblk(vp, i, NFS_DIRBLKSIZ, td);
  606                             if (!bp) {
  607                                 error = nfs_sigintr(nmp, NULL, td);
  608                                 return (error ? error : EINTR);
  609                             }
  610                             if ((bp->b_flags & B_CACHE) == 0) {
  611                                     bp->b_iocmd = BIO_READ;
  612                                     vfs_busy_pages(bp, 0);
  613                                     error = nfs_doio(vp, bp, cred, td);
  614                                     /*
  615                                      * no error + B_INVAL == directory EOF,
  616                                      * use the block.
  617                                      */
  618                                     if (error == 0 && (bp->b_flags & B_INVAL))
  619                                             break;
  620                             }
  621                             /*
  622                              * An error will throw away the block and the
  623                              * for loop will break out.  If no error and this
  624                              * is not the block we want, we throw away the
  625                              * block and go for the next one via the for loop.
  626                              */
  627                             if (error || i < lbn)
  628                                     brelse(bp);
  629                         }
  630                     }
  631                     /*
  632                      * The above while is repeated if we hit another cookie
  633                      * error.  If we hit an error and it wasn't a cookie error,
  634                      * we give up.
  635                      */
  636                     if (error)
  637                             return (error);
  638                 }
  639 
  640                 /*
  641                  * If not eof and read aheads are enabled, start one.
  642                  * (You need the current block first, so that you have the
  643                  *  directory offset cookie of the next block.)
  644                  */
  645                 if (nmp->nm_readahead > 0 &&
  646                     (bp->b_flags & B_INVAL) == 0 &&
  647                     (np->n_direofoffset == 0 ||
  648                     (lbn + 1) * NFS_DIRBLKSIZ < np->n_direofoffset) &&
  649                     incore(&vp->v_bufobj, lbn + 1) == NULL) {
  650                         rabp = nfs_getcacheblk(vp, lbn + 1, NFS_DIRBLKSIZ, td);
  651                         if (rabp) {
  652                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  653                                 rabp->b_flags |= B_ASYNC;
  654                                 rabp->b_iocmd = BIO_READ;
  655                                 vfs_busy_pages(rabp, 0);
  656                                 if (nfs_asyncio(nmp, rabp, cred, td)) {
  657                                     rabp->b_flags |= B_INVAL;
  658                                     rabp->b_ioflags |= BIO_ERROR;
  659                                     vfs_unbusy_pages(rabp);
  660                                     brelse(rabp);
  661                                 }
  662                             } else {
  663                                 brelse(rabp);
  664                             }
  665                         }
  666                 }
  667                 /*
  668                  * Unlike VREG files, whos buffer size ( bp->b_bcount ) is
  669                  * chopped for the EOF condition, we cannot tell how large
  670                  * NFS directories are going to be until we hit EOF.  So
  671                  * an NFS directory buffer is *not* chopped to its EOF.  Now,
  672                  * it just so happens that b_resid will effectively chop it
  673                  * to EOF.  *BUT* this information is lost if the buffer goes
  674                  * away and is reconstituted into a B_CACHE state ( due to
  675                  * being VMIO ) later.  So we keep track of the directory eof
  676                  * in np->n_direofoffset and chop it off as an extra step
  677                  * right here.
  678                  */
  679                 n = lmin(uio->uio_resid, NFS_DIRBLKSIZ - bp->b_resid - on);
  680                 if (np->n_direofoffset && n > np->n_direofoffset - uio->uio_offset)
  681                         n = np->n_direofoffset - uio->uio_offset;
  682                 break;
  683             default:
  684                 printf(" nfs_bioread: type %x unexpected\n", vp->v_type);
  685                 bp = NULL;
  686                 break;
  687             };
  688 
  689             if (n > 0) {
  690                     error = uiomove(bp->b_data + on, (int)n, uio);
  691             }
  692             if (vp->v_type == VLNK)
  693                 n = 0;
  694             if (bp != NULL)
  695                 brelse(bp);
  696         } while (error == 0 && uio->uio_resid > 0 && n > 0);
  697         return (error);
  698 }
  699 
  700 /*
  701  * The NFS write path cannot handle iovecs with len > 1. So we need to 
  702  * break up iovecs accordingly (restricting them to wsize).
  703  * For the SYNC case, we can do this with 1 copy (user buffer -> mbuf). 
  704  * For the ASYNC case, 2 copies are needed. The first a copy from the 
  705  * user buffer to a staging buffer and then a second copy from the staging
  706  * buffer to mbufs. This can be optimized by copying from the user buffer
  707  * directly into mbufs and passing the chain down, but that requires a 
  708  * fair amount of re-working of the relevant codepaths (and can be done
  709  * later).
  710  */
  711 static int
  712 nfs_directio_write(vp, uiop, cred, ioflag)
  713         struct vnode *vp;
  714         struct uio *uiop;
  715         struct ucred *cred;
  716         int ioflag;
  717 {
  718         int error;
  719         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  720         struct thread *td = uiop->uio_td;
  721         int size;
  722 
  723         if (ioflag & IO_SYNC) {
  724                 int iomode, must_commit;
  725                 struct uio uio;
  726                 struct iovec iov;
  727 do_sync:
  728                 while (uiop->uio_resid > 0) {
  729                         size = min(uiop->uio_resid, nmp->nm_wsize);
  730                         size = min(uiop->uio_iov->iov_len, size);
  731                         iov.iov_base = uiop->uio_iov->iov_base;
  732                         iov.iov_len = size;
  733                         uio.uio_iov = &iov;
  734                         uio.uio_iovcnt = 1;
  735                         uio.uio_offset = uiop->uio_offset;
  736                         uio.uio_resid = size;
  737                         uio.uio_segflg = UIO_USERSPACE;
  738                         uio.uio_rw = UIO_WRITE;
  739                         uio.uio_td = td;
  740                         iomode = NFSV3WRITE_FILESYNC;
  741                         error = (nmp->nm_rpcops->nr_writerpc)(vp, &uio, cred, 
  742                                                       &iomode, &must_commit);
  743                         KASSERT((must_commit == 0), 
  744                                 ("nfs_directio_write: Did not commit write"));
  745                         if (error)
  746                                 return (error);
  747                         uiop->uio_offset += size;
  748                         uiop->uio_resid -= size;
  749                         if (uiop->uio_iov->iov_len <= size) {
  750                                 uiop->uio_iovcnt--;
  751                                 uiop->uio_iov++;
  752                         } else {
  753                                 uiop->uio_iov->iov_base = 
  754                                         (char *)uiop->uio_iov->iov_base + size;
  755                                 uiop->uio_iov->iov_len -= size;
  756                         }
  757                 }
  758         } else {
  759                 struct uio *t_uio;
  760                 struct iovec *t_iov;
  761                 struct buf *bp;
  762                 
  763                 /*
  764                  * Break up the write into blocksize chunks and hand these
  765                  * over to nfsiod's for write back.
  766                  * Unfortunately, this incurs a copy of the data. Since 
  767                  * the user could modify the buffer before the write is 
  768                  * initiated.
  769                  * 
  770                  * The obvious optimization here is that one of the 2 copies
  771                  * in the async write path can be eliminated by copying the
  772                  * data here directly into mbufs and passing the mbuf chain
  773                  * down. But that will require a fair amount of re-working
  774                  * of the code and can be done if there's enough interest
  775                  * in NFS directio access.
  776                  */
  777                 while (uiop->uio_resid > 0) {
  778                         size = min(uiop->uio_resid, nmp->nm_wsize);
  779                         size = min(uiop->uio_iov->iov_len, size);
  780                         bp = getpbuf(&nfs_pbuf_freecnt);
  781                         t_uio = malloc(sizeof(struct uio), M_NFSDIRECTIO, M_WAITOK);
  782                         t_iov = malloc(sizeof(struct iovec), M_NFSDIRECTIO, M_WAITOK);
  783                         t_iov->iov_base = malloc(size, M_NFSDIRECTIO, M_WAITOK);
  784                         t_iov->iov_len = size;
  785                         t_uio->uio_iov = t_iov;
  786                         t_uio->uio_iovcnt = 1;
  787                         t_uio->uio_offset = uiop->uio_offset;
  788                         t_uio->uio_resid = size;
  789                         t_uio->uio_segflg = UIO_SYSSPACE;
  790                         t_uio->uio_rw = UIO_WRITE;
  791                         t_uio->uio_td = td;
  792                         bcopy(uiop->uio_iov->iov_base, t_iov->iov_base, size);
  793                         bp->b_flags |= B_DIRECT;
  794                         bp->b_iocmd = BIO_WRITE;
  795                         if (cred != NOCRED) {
  796                                 crhold(cred);
  797                                 bp->b_wcred = cred;
  798                         } else 
  799                                 bp->b_wcred = NOCRED;                   
  800                         bp->b_caller1 = (void *)t_uio;
  801                         bp->b_vp = vp;
  802                         vhold(vp);
  803                         error = nfs_asyncio(nmp, bp, NOCRED, td);
  804                         if (error) {
  805                                 free(t_iov->iov_base, M_NFSDIRECTIO);
  806                                 free(t_iov, M_NFSDIRECTIO);
  807                                 free(t_uio, M_NFSDIRECTIO);
  808                                 vdrop(bp->b_vp);
  809                                 bp->b_vp = NULL;
  810                                 relpbuf(bp, &nfs_pbuf_freecnt);
  811                                 if (error == EINTR)
  812                                         return (error);
  813                                 goto do_sync;
  814                         }
  815                         uiop->uio_offset += size;
  816                         uiop->uio_resid -= size;
  817                         if (uiop->uio_iov->iov_len <= size) {
  818                                 uiop->uio_iovcnt--;
  819                                 uiop->uio_iov++;
  820                         } else {
  821                                 uiop->uio_iov->iov_base = 
  822                                         (char *)uiop->uio_iov->iov_base + size;
  823                                 uiop->uio_iov->iov_len -= size;
  824                         }
  825                 }
  826         }
  827         return (0);
  828 }
  829 
  830 /*
  831  * Vnode op for write using bio
  832  */
  833 int
  834 nfs_write(struct vop_write_args *ap)
  835 {
  836         int biosize;
  837         struct uio *uio = ap->a_uio;
  838         struct thread *td = uio->uio_td;
  839         struct vnode *vp = ap->a_vp;
  840         struct nfsnode *np = VTONFS(vp);
  841         struct ucred *cred = ap->a_cred;
  842         int ioflag = ap->a_ioflag;
  843         struct buf *bp;
  844         struct vattr vattr;
  845         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  846         daddr_t lbn;
  847         int bcount;
  848         int n, on, error = 0;
  849         int haverslock = 0;
  850         struct proc *p = td?td->td_proc:NULL;
  851 
  852         GIANT_REQUIRED;
  853 
  854 #ifdef DIAGNOSTIC
  855         if (uio->uio_rw != UIO_WRITE)
  856                 panic("nfs_write mode");
  857         if (uio->uio_segflg == UIO_USERSPACE && uio->uio_td != curthread)
  858                 panic("nfs_write proc");
  859 #endif
  860         if (vp->v_type != VREG)
  861                 return (EIO);
  862         if (np->n_flag & NWRITEERR) {
  863                 np->n_flag &= ~NWRITEERR;
  864                 return (np->n_error);
  865         }
  866         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  867             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0)
  868                 (void)nfs_fsinfo(nmp, vp, cred, td);
  869 
  870         /*
  871          * Synchronously flush pending buffers if we are in synchronous
  872          * mode or if we are appending.
  873          */
  874         if (ioflag & (IO_APPEND | IO_SYNC)) {
  875                 if (np->n_flag & NMODIFIED) {
  876 #ifdef notyet /* Needs matching nonblock semantics elsewhere, too. */
  877                         /*
  878                          * Require non-blocking, synchronous writes to
  879                          * dirty files to inform the program it needs
  880                          * to fsync(2) explicitly.
  881                          */
  882                         if (ioflag & IO_NDELAY)
  883                                 return (EAGAIN);
  884 #endif
  885 flush_and_restart:
  886                         np->n_attrstamp = 0;
  887                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  888                         if (error)
  889                                 return (error);
  890                 }
  891         }
  892 
  893         /*
  894          * If IO_APPEND then load uio_offset.  We restart here if we cannot
  895          * get the append lock.
  896          */
  897 restart:
  898         if (ioflag & IO_APPEND) {
  899                 np->n_attrstamp = 0;
  900                 error = VOP_GETATTR(vp, &vattr, cred, td);
  901                 if (error)
  902                         return (error);
  903                 uio->uio_offset = np->n_size;
  904         }
  905 
  906         if (uio->uio_offset < 0)
  907                 return (EINVAL);
  908         if ((uio->uio_offset + uio->uio_resid) > nmp->nm_maxfilesize)
  909                 return (EFBIG);
  910         if (uio->uio_resid == 0)
  911                 return (0);
  912 
  913         if (nfs_directio_enable && (ioflag & IO_DIRECT) && vp->v_type == VREG)
  914                 return nfs_directio_write(vp, uio, cred, ioflag);
  915 
  916         /*
  917          * We need to obtain the rslock if we intend to modify np->n_size
  918          * in order to guarentee the append point with multiple contending
  919          * writers, to guarentee that no other appenders modify n_size
  920          * while we are trying to obtain a truncated buffer (i.e. to avoid
  921          * accidently truncating data written by another appender due to
  922          * the race), and to ensure that the buffer is populated prior to
  923          * our extending of the file.  We hold rslock through the entire
  924          * operation.
  925          *
  926          * Note that we do not synchronize the case where someone truncates
  927          * the file while we are appending to it because attempting to lock
  928          * this case may deadlock other parts of the system unexpectedly.
  929          */
  930         if ((ioflag & IO_APPEND) ||
  931             uio->uio_offset + uio->uio_resid > np->n_size) {
  932                 switch(nfs_rslock(np, td)) {
  933                 case ENOLCK:
  934                         goto restart;
  935                         /* not reached */
  936                 case EIO:
  937                         return (EIO);
  938                 case EINTR:
  939                 case ERESTART:
  940                         return(EINTR);
  941                         /* not reached */
  942                 default:
  943                         break;
  944                 }
  945                 haverslock = 1;
  946         }
  947 
  948         /*
  949          * Maybe this should be above the vnode op call, but so long as
  950          * file servers have no limits, i don't think it matters
  951          */
  952         if (p != NULL) {
  953                 PROC_LOCK(p);
  954                 if (uio->uio_offset + uio->uio_resid >
  955                     lim_cur(p, RLIMIT_FSIZE)) {
  956                         psignal(p, SIGXFSZ);
  957                         PROC_UNLOCK(p);
  958                         if (haverslock)
  959                                 nfs_rsunlock(np, td);
  960                         return (EFBIG);
  961                 }
  962                 PROC_UNLOCK(p);
  963         }
  964 
  965         biosize = vp->v_mount->mnt_stat.f_iosize;
  966         /*
  967          * Find all of this file's B_NEEDCOMMIT buffers.  If our writes
  968          * would exceed the local maximum per-file write commit size when
  969          * combined with those, we must decide whether to flush,
  970          * go synchronous, or return error.  We don't bother checking
  971          * IO_UNIT -- we just make all writes atomic anyway, as there's
  972          * no point optimizing for something that really won't ever happen.
  973          */
  974         if (!(ioflag & IO_SYNC)) {
  975                 int needrestart = 0;
  976                 if (nmp->nm_wcommitsize < uio->uio_resid) {
  977                         /*
  978                          * If this request could not possibly be completed
  979                          * without exceeding the maximum outstanding write
  980                          * commit size, see if we can convert it into a
  981                          * synchronous write operation.
  982                          */
  983                         if (ioflag & IO_NDELAY)
  984                                 return (EAGAIN);
  985                         ioflag |= IO_SYNC;
  986                         if (np->n_flag & NMODIFIED)
  987                                 needrestart = 1;
  988                 } else if (np->n_flag & NMODIFIED) {
  989                         int wouldcommit = 0;
  990                         BO_LOCK(&vp->v_bufobj);
  991                         if (vp->v_bufobj.bo_dirty.bv_cnt != 0) {
  992                                 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd,
  993                                     b_bobufs) {
  994                                         if (bp->b_flags & B_NEEDCOMMIT)
  995                                                 wouldcommit += bp->b_bcount;
  996                                 }
  997                         }
  998                         BO_UNLOCK(&vp->v_bufobj);
  999                         /*
 1000                          * Since we're not operating synchronously and
 1001                          * bypassing the buffer cache, we are in a commit
 1002                          * and holding all of these buffers whether
 1003                          * transmitted or not.  If not limited, this
 1004                          * will lead to the buffer cache deadlocking,
 1005                          * as no one else can flush our uncommitted buffers.
 1006                          */
 1007                         wouldcommit += uio->uio_resid;
 1008                         /*
 1009                          * If we would initially exceed the maximum
 1010                          * outstanding write commit size, flush and restart.
 1011                          */
 1012                         if (wouldcommit > nmp->nm_wcommitsize)
 1013                                 needrestart = 1;
 1014                 }
 1015                 if (needrestart) {
 1016                         if (haverslock) {
 1017                                 nfs_rsunlock(np, td);
 1018                                 haverslock = 0;
 1019                         }
 1020                         goto flush_and_restart;
 1021                 }
 1022         }
 1023 
 1024         do {
 1025                 nfsstats.biocache_writes++;
 1026                 lbn = uio->uio_offset / biosize;
 1027                 on = uio->uio_offset & (biosize-1);
 1028                 n = min((unsigned)(biosize - on), uio->uio_resid);
 1029 again:
 1030                 /*
 1031                  * Handle direct append and file extension cases, calculate
 1032                  * unaligned buffer size.
 1033                  */
 1034 
 1035                 if (uio->uio_offset == np->n_size && n) {
 1036                         /*
 1037                          * Get the buffer (in its pre-append state to maintain
 1038                          * B_CACHE if it was previously set).  Resize the
 1039                          * nfsnode after we have locked the buffer to prevent
 1040                          * readers from reading garbage.
 1041                          */
 1042                         bcount = on;
 1043                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1044 
 1045                         if (bp != NULL) {
 1046                                 long save;
 1047 
 1048                                 np->n_size = uio->uio_offset + n;
 1049                                 np->n_flag |= NMODIFIED;
 1050                                 vnode_pager_setsize(vp, np->n_size);
 1051 
 1052                                 save = bp->b_flags & B_CACHE;
 1053                                 bcount += n;
 1054                                 allocbuf(bp, bcount);
 1055                                 bp->b_flags |= save;
 1056                         }
 1057                 } else {
 1058                         /*
 1059                          * Obtain the locked cache block first, and then
 1060                          * adjust the file's size as appropriate.
 1061                          */
 1062                         bcount = on + n;
 1063                         if ((off_t)lbn * biosize + bcount < np->n_size) {
 1064                                 if ((off_t)(lbn + 1) * biosize < np->n_size)
 1065                                         bcount = biosize;
 1066                                 else
 1067                                         bcount = np->n_size - (off_t)lbn * biosize;
 1068                         }
 1069                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1070                         if (uio->uio_offset + n > np->n_size) {
 1071                                 np->n_size = uio->uio_offset + n;
 1072                                 np->n_flag |= NMODIFIED;
 1073                                 vnode_pager_setsize(vp, np->n_size);
 1074                         }
 1075                 }
 1076 
 1077                 if (!bp) {
 1078                         error = nfs_sigintr(nmp, NULL, td);
 1079                         if (!error)
 1080                                 error = EINTR;
 1081                         break;
 1082                 }
 1083 
 1084                 /*
 1085                  * Issue a READ if B_CACHE is not set.  In special-append
 1086                  * mode, B_CACHE is based on the buffer prior to the write
 1087                  * op and is typically set, avoiding the read.  If a read
 1088                  * is required in special append mode, the server will
 1089                  * probably send us a short-read since we extended the file
 1090                  * on our end, resulting in b_resid == 0 and, thusly,
 1091                  * B_CACHE getting set.
 1092                  *
 1093                  * We can also avoid issuing the read if the write covers
 1094                  * the entire buffer.  We have to make sure the buffer state
 1095                  * is reasonable in this case since we will not be initiating
 1096                  * I/O.  See the comments in kern/vfs_bio.c's getblk() for
 1097                  * more information.
 1098                  *
 1099                  * B_CACHE may also be set due to the buffer being cached
 1100                  * normally.
 1101                  */
 1102 
 1103                 if (on == 0 && n == bcount) {
 1104                         bp->b_flags |= B_CACHE;
 1105                         bp->b_flags &= ~B_INVAL;
 1106                         bp->b_ioflags &= ~BIO_ERROR;
 1107                 }
 1108 
 1109                 if ((bp->b_flags & B_CACHE) == 0) {
 1110                         bp->b_iocmd = BIO_READ;
 1111                         vfs_busy_pages(bp, 0);
 1112                         error = nfs_doio(vp, bp, cred, td);
 1113                         if (error) {
 1114                                 brelse(bp);
 1115                                 break;
 1116                         }
 1117                 }
 1118                 if (bp->b_wcred == NOCRED)
 1119                         bp->b_wcred = crhold(cred);
 1120                 np->n_flag |= NMODIFIED;
 1121 
 1122                 /*
 1123                  * If dirtyend exceeds file size, chop it down.  This should
 1124                  * not normally occur but there is an append race where it
 1125                  * might occur XXX, so we log it.
 1126                  *
 1127                  * If the chopping creates a reverse-indexed or degenerate
 1128                  * situation with dirtyoff/end, we 0 both of them.
 1129                  */
 1130 
 1131                 if (bp->b_dirtyend > bcount) {
 1132                         printf("NFS append race @%lx:%d\n",
 1133                             (long)bp->b_blkno * DEV_BSIZE,
 1134                             bp->b_dirtyend - bcount);
 1135                         bp->b_dirtyend = bcount;
 1136                 }
 1137 
 1138                 if (bp->b_dirtyoff >= bp->b_dirtyend)
 1139                         bp->b_dirtyoff = bp->b_dirtyend = 0;
 1140 
 1141                 /*
 1142                  * If the new write will leave a contiguous dirty
 1143                  * area, just update the b_dirtyoff and b_dirtyend,
 1144                  * otherwise force a write rpc of the old dirty area.
 1145                  *
 1146                  * While it is possible to merge discontiguous writes due to
 1147                  * our having a B_CACHE buffer ( and thus valid read data
 1148                  * for the hole), we don't because it could lead to
 1149                  * significant cache coherency problems with multiple clients,
 1150                  * especially if locking is implemented later on.
 1151                  *
 1152                  * as an optimization we could theoretically maintain
 1153                  * a linked list of discontinuous areas, but we would still
 1154                  * have to commit them separately so there isn't much
 1155                  * advantage to it except perhaps a bit of asynchronization.
 1156                  */
 1157 
 1158                 if (bp->b_dirtyend > 0 &&
 1159                     (on > bp->b_dirtyend || (on + n) < bp->b_dirtyoff)) {
 1160                         if (bwrite(bp) == EINTR) {
 1161                                 error = EINTR;
 1162                                 break;
 1163                         }
 1164                         goto again;
 1165                 }
 1166 
 1167                 error = uiomove((char *)bp->b_data + on, n, uio);
 1168 
 1169                 /*
 1170                  * Since this block is being modified, it must be written
 1171                  * again and not just committed.  Since write clustering does
 1172                  * not work for the stage 1 data write, only the stage 2
 1173                  * commit rpc, we have to clear B_CLUSTEROK as well.
 1174                  */
 1175                 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1176 
 1177                 if (error) {
 1178                         bp->b_ioflags |= BIO_ERROR;
 1179                         brelse(bp);
 1180                         break;
 1181                 }
 1182 
 1183                 /*
 1184                  * Only update dirtyoff/dirtyend if not a degenerate
 1185                  * condition.
 1186                  */
 1187                 if (n) {
 1188                         if (bp->b_dirtyend > 0) {
 1189                                 bp->b_dirtyoff = min(on, bp->b_dirtyoff);
 1190                                 bp->b_dirtyend = max((on + n), bp->b_dirtyend);
 1191                         } else {
 1192                                 bp->b_dirtyoff = on;
 1193                                 bp->b_dirtyend = on + n;
 1194                         }
 1195                         vfs_bio_set_validclean(bp, on, n);
 1196                 }
 1197 
 1198                 /*
 1199                  * If IO_SYNC do bwrite().
 1200                  *
 1201                  * IO_INVAL appears to be unused.  The idea appears to be
 1202                  * to turn off caching in this case.  Very odd.  XXX
 1203                  */
 1204                 if ((ioflag & IO_SYNC)) {
 1205                         if (ioflag & IO_INVAL)
 1206                                 bp->b_flags |= B_NOCACHE;
 1207                         error = bwrite(bp);
 1208                         if (error)
 1209                                 break;
 1210                 } else if ((n + on) == biosize) {
 1211                         bp->b_flags |= B_ASYNC;
 1212                         (void) (nmp->nm_rpcops->nr_writebp)(bp, 0, 0);
 1213                 } else {
 1214                         bdwrite(bp);
 1215                 }
 1216         } while (uio->uio_resid > 0 && n > 0);
 1217 
 1218         if (haverslock)
 1219                 nfs_rsunlock(np, td);
 1220 
 1221         return (error);
 1222 }
 1223 
 1224 /*
 1225  * Get an nfs cache block.
 1226  *
 1227  * Allocate a new one if the block isn't currently in the cache
 1228  * and return the block marked busy. If the calling process is
 1229  * interrupted by a signal for an interruptible mount point, return
 1230  * NULL.
 1231  *
 1232  * The caller must carefully deal with the possible B_INVAL state of
 1233  * the buffer.  nfs_doio() clears B_INVAL (and nfs_asyncio() clears it
 1234  * indirectly), so synchronous reads can be issued without worrying about
 1235  * the B_INVAL state.  We have to be a little more careful when dealing
 1236  * with writes (see comments in nfs_write()) when extending a file past
 1237  * its EOF.
 1238  */
 1239 static struct buf *
 1240 nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size, struct thread *td)
 1241 {
 1242         struct buf *bp;
 1243         struct mount *mp;
 1244         struct nfsmount *nmp;
 1245 
 1246         mp = vp->v_mount;
 1247         nmp = VFSTONFS(mp);
 1248 
 1249         if (nmp->nm_flag & NFSMNT_INT) {
 1250                 sigset_t oldset;
 1251 
 1252                 nfs_set_sigmask(td, &oldset);
 1253                 bp = getblk(vp, bn, size, PCATCH, 0, 0);
 1254                 nfs_restore_sigmask(td, &oldset);
 1255                 while (bp == NULL) {
 1256                         if (nfs_sigintr(nmp, NULL, td))
 1257                                 return (NULL);
 1258                         bp = getblk(vp, bn, size, 0, 2 * hz, 0);
 1259                 }
 1260         } else {
 1261                 bp = getblk(vp, bn, size, 0, 0, 0);
 1262         }
 1263 
 1264         if (vp->v_type == VREG) {
 1265                 int biosize;
 1266 
 1267                 biosize = mp->mnt_stat.f_iosize;
 1268                 bp->b_blkno = bn * (biosize / DEV_BSIZE);
 1269         }
 1270         return (bp);
 1271 }
 1272 
 1273 /*
 1274  * Flush and invalidate all dirty buffers. If another process is already
 1275  * doing the flush, just wait for completion.
 1276  */
 1277 int
 1278 nfs_vinvalbuf(struct vnode *vp, int flags, struct thread *td, int intrflg)
 1279 {
 1280         struct nfsnode *np = VTONFS(vp);
 1281         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
 1282         int error = 0, slpflag, slptimeo;
 1283         int old_lock = 0;
 1284 
 1285         ASSERT_VOP_LOCKED(vp, "nfs_vinvalbuf");
 1286 
 1287         /*
 1288          * XXX This check stops us from needlessly doing a vinvalbuf when
 1289          * being called through vclean().  It is not clear that this is
 1290          * unsafe.
 1291          */
 1292         if (vp->v_iflag & VI_DOOMED)
 1293                 return (0);
 1294 
 1295         if ((nmp->nm_flag & NFSMNT_INT) == 0)
 1296                 intrflg = 0;
 1297         if (intrflg) {
 1298                 slpflag = PCATCH;
 1299                 slptimeo = 2 * hz;
 1300         } else {
 1301                 slpflag = 0;
 1302                 slptimeo = 0;
 1303         }
 1304 
 1305         if ((old_lock = VOP_ISLOCKED(vp, td)) != LK_EXCLUSIVE) {
 1306                 if (old_lock == LK_SHARED) {
 1307                         /* Upgrade to exclusive lock, this might block */
 1308                         vn_lock(vp, LK_UPGRADE | LK_RETRY, td);
 1309                 } else {
 1310                         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
 1311                 }
 1312         }
 1313 
 1314         /*
 1315          * Now, flush as required.
 1316          */
 1317         error = vinvalbuf(vp, flags, td, slpflag, 0);
 1318         while (error) {
 1319                 if (intrflg && (error = nfs_sigintr(nmp, NULL, td)))
 1320                         goto out;
 1321                 error = vinvalbuf(vp, flags, td, 0, slptimeo);
 1322         }
 1323         np->n_flag &= ~NMODIFIED;
 1324 out:
 1325         if (old_lock != LK_EXCLUSIVE) {
 1326                 if (old_lock == LK_SHARED) {
 1327                         /* Downgrade from exclusive lock, this might block */
 1328                         vn_lock(vp, LK_DOWNGRADE, td);
 1329                 } else {
 1330                         VOP_UNLOCK(vp, 0, td);
 1331                 }
 1332         }
 1333         return error;
 1334 }
 1335 
 1336 /*
 1337  * Initiate asynchronous I/O. Return an error if no nfsiods are available.
 1338  * This is mainly to avoid queueing async I/O requests when the nfsiods
 1339  * are all hung on a dead server.
 1340  *
 1341  * Note: nfs_asyncio() does not clear (BIO_ERROR|B_INVAL) but when the bp
 1342  * is eventually dequeued by the async daemon, nfs_doio() *will*.
 1343  */
 1344 int
 1345 nfs_asyncio(struct nfsmount *nmp, struct buf *bp, struct ucred *cred, struct thread *td)
 1346 {
 1347         int iod;
 1348         int gotiod;
 1349         int slpflag = 0;
 1350         int slptimeo = 0;
 1351         int error, error2;
 1352 
 1353         /*
 1354          * Commits are usually short and sweet so lets save some cpu and
 1355          * leave the async daemons for more important rpc's (such as reads
 1356          * and writes).
 1357          */
 1358         if (bp->b_iocmd == BIO_WRITE && (bp->b_flags & B_NEEDCOMMIT) &&
 1359             (nmp->nm_bufqiods > nfs_numasync / 2)) {
 1360                 return(EIO);
 1361         }
 1362 
 1363 again:
 1364         if (nmp->nm_flag & NFSMNT_INT)
 1365                 slpflag = PCATCH;
 1366         gotiod = FALSE;
 1367 
 1368         /*
 1369          * Find a free iod to process this request.
 1370          */
 1371         for (iod = 0; iod < nfs_numasync; iod++)
 1372                 if (nfs_iodwant[iod]) {
 1373                         gotiod = TRUE;
 1374                         break;
 1375                 }
 1376 
 1377         /*
 1378          * Try to create one if none are free.
 1379          */
 1380         if (!gotiod) {
 1381                 iod = nfs_nfsiodnew();
 1382                 if (iod != -1)
 1383                         gotiod = TRUE;
 1384         }
 1385 
 1386         if (gotiod) {
 1387                 /*
 1388                  * Found one, so wake it up and tell it which
 1389                  * mount to process.
 1390                  */
 1391                 NFS_DPF(ASYNCIO, ("nfs_asyncio: waking iod %d for mount %p\n",
 1392                     iod, nmp));
 1393                 nfs_iodwant[iod] = NULL;
 1394                 nfs_iodmount[iod] = nmp;
 1395                 nmp->nm_bufqiods++;
 1396                 wakeup(&nfs_iodwant[iod]);
 1397         }
 1398 
 1399         /*
 1400          * If none are free, we may already have an iod working on this mount
 1401          * point.  If so, it will process our request.
 1402          */
 1403         if (!gotiod) {
 1404                 if (nmp->nm_bufqiods > 0) {
 1405                         NFS_DPF(ASYNCIO,
 1406                                 ("nfs_asyncio: %d iods are already processing mount %p\n",
 1407                                  nmp->nm_bufqiods, nmp));
 1408                         gotiod = TRUE;
 1409                 }
 1410         }
 1411 
 1412         /*
 1413          * If we have an iod which can process the request, then queue
 1414          * the buffer.
 1415          */
 1416         if (gotiod) {
 1417                 /*
 1418                  * Ensure that the queue never grows too large.  We still want
 1419                  * to asynchronize so we block rather then return EIO.
 1420                  */
 1421                 while (nmp->nm_bufqlen >= 2*nfs_numasync) {
 1422                         NFS_DPF(ASYNCIO,
 1423                                 ("nfs_asyncio: waiting for mount %p queue to drain\n", nmp));
 1424                         nmp->nm_bufqwant = TRUE;
 1425                         error = nfs_tsleep(td, &nmp->nm_bufq, slpflag | PRIBIO,
 1426                                            "nfsaio", slptimeo);
 1427                         if (error) {
 1428                                 error2 = nfs_sigintr(nmp, NULL, td);
 1429                                 if (error2)
 1430                                         return (error2);
 1431                                 if (slpflag == PCATCH) {
 1432                                         slpflag = 0;
 1433                                         slptimeo = 2 * hz;
 1434                                 }
 1435                         }
 1436                         /*
 1437                          * We might have lost our iod while sleeping,
 1438                          * so check and loop if nescessary.
 1439                          */
 1440                         if (nmp->nm_bufqiods == 0) {
 1441                                 NFS_DPF(ASYNCIO,
 1442                                         ("nfs_asyncio: no iods after mount %p queue was drained, looping\n", nmp));
 1443                                 goto again;
 1444                         }
 1445                 }
 1446 
 1447                 if (bp->b_iocmd == BIO_READ) {
 1448                         if (bp->b_rcred == NOCRED && cred != NOCRED)
 1449                                 bp->b_rcred = crhold(cred);
 1450                 } else {
 1451                         if (bp->b_wcred == NOCRED && cred != NOCRED)
 1452                                 bp->b_wcred = crhold(cred);
 1453                 }
 1454 
 1455                 if (bp->b_flags & B_REMFREE)
 1456                         bremfreef(bp);
 1457                 BUF_KERNPROC(bp);
 1458                 TAILQ_INSERT_TAIL(&nmp->nm_bufq, bp, b_freelist);
 1459                 nmp->nm_bufqlen++;
 1460                 return (0);
 1461         }
 1462 
 1463         /*
 1464          * All the iods are busy on other mounts, so return EIO to
 1465          * force the caller to process the i/o synchronously.
 1466          */
 1467         NFS_DPF(ASYNCIO, ("nfs_asyncio: no iods available, i/o is synchronous\n"));
 1468         return (EIO);
 1469 }
 1470 
 1471 void
 1472 nfs_doio_directwrite(struct buf *bp)
 1473 {
 1474         int iomode, must_commit;
 1475         struct uio *uiop = (struct uio *)bp->b_caller1;
 1476         char *iov_base = uiop->uio_iov->iov_base;
 1477         struct nfsmount *nmp = VFSTONFS(bp->b_vp->v_mount);
 1478         
 1479         iomode = NFSV3WRITE_FILESYNC;
 1480         uiop->uio_td = NULL; /* NULL since we're in nfsiod */
 1481         (nmp->nm_rpcops->nr_writerpc)(bp->b_vp, uiop, bp->b_wcred, &iomode, &must_commit);
 1482         KASSERT((must_commit == 0), ("nfs_doio_directwrite: Did not commit write"));
 1483         free(iov_base, M_NFSDIRECTIO);
 1484         free(uiop->uio_iov, M_NFSDIRECTIO);
 1485         free(uiop, M_NFSDIRECTIO);
 1486         vdrop(bp->b_vp);
 1487         bp->b_vp = NULL;
 1488         relpbuf(bp, &nfs_pbuf_freecnt);
 1489 }
 1490 
 1491 /*
 1492  * Do an I/O operation to/from a cache block. This may be called
 1493  * synchronously or from an nfsiod.
 1494  */
 1495 int
 1496 nfs_doio(struct vnode *vp, struct buf *bp, struct ucred *cr, struct thread *td)
 1497 {
 1498         struct uio *uiop;
 1499         struct nfsnode *np;
 1500         struct nfsmount *nmp;
 1501         int error = 0, iomode, must_commit = 0;
 1502         struct uio uio;
 1503         struct iovec io;
 1504         struct proc *p = td ? td->td_proc : NULL;
 1505 
 1506         np = VTONFS(vp);
 1507         nmp = VFSTONFS(vp->v_mount);
 1508         uiop = &uio;
 1509         uiop->uio_iov = &io;
 1510         uiop->uio_iovcnt = 1;
 1511         uiop->uio_segflg = UIO_SYSSPACE;
 1512         uiop->uio_td = td;
 1513 
 1514         /*
 1515          * clear BIO_ERROR and B_INVAL state prior to initiating the I/O.  We
 1516          * do this here so we do not have to do it in all the code that
 1517          * calls us.
 1518          */
 1519         bp->b_flags &= ~B_INVAL;
 1520         bp->b_ioflags &= ~BIO_ERROR;
 1521 
 1522         KASSERT(!(bp->b_flags & B_DONE), ("nfs_doio: bp %p already marked done", bp));
 1523 
 1524         if (bp->b_iocmd == BIO_READ) {
 1525             io.iov_len = uiop->uio_resid = bp->b_bcount;
 1526             io.iov_base = bp->b_data;
 1527             uiop->uio_rw = UIO_READ;
 1528 
 1529             switch (vp->v_type) {
 1530             case VREG:
 1531                 uiop->uio_offset = ((off_t)bp->b_blkno) * DEV_BSIZE;
 1532                 nfsstats.read_bios++;
 1533                 error = (nmp->nm_rpcops->nr_readrpc)(vp, uiop, cr);
 1534 
 1535                 if (!error) {
 1536                     if (uiop->uio_resid) {
 1537                         /*
 1538                          * If we had a short read with no error, we must have
 1539                          * hit a file hole.  We should zero-fill the remainder.
 1540                          * This can also occur if the server hits the file EOF.
 1541                          *
 1542                          * Holes used to be able to occur due to pending
 1543                          * writes, but that is not possible any longer.
 1544                          */
 1545                         int nread = bp->b_bcount - uiop->uio_resid;
 1546                         int left  = uiop->uio_resid;
 1547 
 1548                         if (left > 0)
 1549                                 bzero((char *)bp->b_data + nread, left);
 1550                         uiop->uio_resid = 0;
 1551                     }
 1552                 }
 1553                 /* ASSERT_VOP_LOCKED(vp, "nfs_doio"); */
 1554                 if (p && (vp->v_vflag & VV_TEXT) &&
 1555                     (NFS_TIMESPEC_COMPARE(&np->n_mtime, &np->n_vattr.va_mtime))) {
 1556                         PROC_LOCK(p);
 1557                         killproc(p, "text file modification");
 1558                         PROC_UNLOCK(p);
 1559                 }
 1560                 break;
 1561             case VLNK:
 1562                 uiop->uio_offset = (off_t)0;
 1563                 nfsstats.readlink_bios++;
 1564                 error = (nmp->nm_rpcops->nr_readlinkrpc)(vp, uiop, cr);
 1565                 break;
 1566             case VDIR:
 1567                 nfsstats.readdir_bios++;
 1568                 uiop->uio_offset = ((u_quad_t)bp->b_lblkno) * NFS_DIRBLKSIZ;
 1569                 if ((nmp->nm_flag & NFSMNT_NFSV4) != 0)
 1570                         error = nfs4_readdirrpc(vp, uiop, cr);
 1571                 else {
 1572                         if ((nmp->nm_flag & NFSMNT_RDIRPLUS) != 0) {
 1573                                 error = nfs_readdirplusrpc(vp, uiop, cr);
 1574                                 if (error == NFSERR_NOTSUPP)
 1575                                         nmp->nm_flag &= ~NFSMNT_RDIRPLUS;
 1576                         }
 1577                         if ((nmp->nm_flag & NFSMNT_RDIRPLUS) == 0)
 1578                                 error = nfs_readdirrpc(vp, uiop, cr);
 1579                 }
 1580                 /*
 1581                  * end-of-directory sets B_INVAL but does not generate an
 1582                  * error.
 1583                  */
 1584                 if (error == 0 && uiop->uio_resid == bp->b_bcount)
 1585                         bp->b_flags |= B_INVAL;
 1586                 break;
 1587             default:
 1588                 printf("nfs_doio:  type %x unexpected\n", vp->v_type);
 1589                 break;
 1590             };
 1591             if (error) {
 1592                 bp->b_ioflags |= BIO_ERROR;
 1593                 bp->b_error = error;
 1594             }
 1595         } else {
 1596             /*
 1597              * If we only need to commit, try to commit
 1598              */
 1599             if (bp->b_flags & B_NEEDCOMMIT) {
 1600                     int retv;
 1601                     off_t off;
 1602 
 1603                     off = ((u_quad_t)bp->b_blkno) * DEV_BSIZE + bp->b_dirtyoff;
 1604                     retv = (nmp->nm_rpcops->nr_commit)(
 1605                                 vp, off, bp->b_dirtyend-bp->b_dirtyoff,
 1606                                 bp->b_wcred, td);
 1607                     if (retv == 0) {
 1608                             bp->b_dirtyoff = bp->b_dirtyend = 0;
 1609                             bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1610                             bp->b_resid = 0;
 1611                             bufdone(bp);
 1612                             return (0);
 1613                     }
 1614                     if (retv == NFSERR_STALEWRITEVERF) {
 1615                             nfs_clearcommit(vp->v_mount);
 1616                     }
 1617             }
 1618 
 1619             /*
 1620              * Setup for actual write
 1621              */
 1622 
 1623             if ((off_t)bp->b_blkno * DEV_BSIZE + bp->b_dirtyend > np->n_size)
 1624                 bp->b_dirtyend = np->n_size - (off_t)bp->b_blkno * DEV_BSIZE;
 1625 
 1626             if (bp->b_dirtyend > bp->b_dirtyoff) {
 1627                 io.iov_len = uiop->uio_resid = bp->b_dirtyend
 1628                     - bp->b_dirtyoff;
 1629                 uiop->uio_offset = (off_t)bp->b_blkno * DEV_BSIZE
 1630                     + bp->b_dirtyoff;
 1631                 io.iov_base = (char *)bp->b_data + bp->b_dirtyoff;
 1632                 uiop->uio_rw = UIO_WRITE;
 1633                 nfsstats.write_bios++;
 1634 
 1635                 if ((bp->b_flags & (B_ASYNC | B_NEEDCOMMIT | B_NOCACHE | B_CLUSTER)) == B_ASYNC)
 1636                     iomode = NFSV3WRITE_UNSTABLE;
 1637                 else
 1638                     iomode = NFSV3WRITE_FILESYNC;
 1639 
 1640                 error = (nmp->nm_rpcops->nr_writerpc)(vp, uiop, cr, &iomode, &must_commit);
 1641 
 1642                 /*
 1643                  * When setting B_NEEDCOMMIT also set B_CLUSTEROK to try
 1644                  * to cluster the buffers needing commit.  This will allow
 1645                  * the system to submit a single commit rpc for the whole
 1646                  * cluster.  We can do this even if the buffer is not 100%
 1647                  * dirty (relative to the NFS blocksize), so we optimize the
 1648                  * append-to-file-case.
 1649                  *
 1650                  * (when clearing B_NEEDCOMMIT, B_CLUSTEROK must also be
 1651                  * cleared because write clustering only works for commit
 1652                  * rpc's, not for the data portion of the write).
 1653                  */
 1654 
 1655                 if (!error && iomode == NFSV3WRITE_UNSTABLE) {
 1656                     bp->b_flags |= B_NEEDCOMMIT;
 1657                     if (bp->b_dirtyoff == 0
 1658                         && bp->b_dirtyend == bp->b_bcount)
 1659                         bp->b_flags |= B_CLUSTEROK;
 1660                 } else {
 1661                     bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1662                 }
 1663 
 1664                 /*
 1665                  * For an interrupted write, the buffer is still valid
 1666                  * and the write hasn't been pushed to the server yet,
 1667                  * so we can't set BIO_ERROR and report the interruption
 1668                  * by setting B_EINTR. For the B_ASYNC case, B_EINTR
 1669                  * is not relevant, so the rpc attempt is essentially
 1670                  * a noop.  For the case of a V3 write rpc not being
 1671                  * committed to stable storage, the block is still
 1672                  * dirty and requires either a commit rpc or another
 1673                  * write rpc with iomode == NFSV3WRITE_FILESYNC before
 1674                  * the block is reused. This is indicated by setting
 1675                  * the B_DELWRI and B_NEEDCOMMIT flags.
 1676                  *
 1677                  * If the buffer is marked B_PAGING, it does not reside on
 1678                  * the vp's paging queues so we cannot call bdirty().  The
 1679                  * bp in this case is not an NFS cache block so we should
 1680                  * be safe. XXX
 1681                  */
 1682                 if (error == EINTR || error == EIO
 1683                     || (!error && (bp->b_flags & B_NEEDCOMMIT))) {
 1684                         int s;
 1685 
 1686                         s = splbio();
 1687                         bp->b_flags &= ~(B_INVAL|B_NOCACHE);
 1688                         if ((bp->b_flags & B_PAGING) == 0) {
 1689                             bdirty(bp);
 1690                             bp->b_flags &= ~B_DONE;
 1691                         }
 1692                         if (error && (bp->b_flags & B_ASYNC) == 0)
 1693                             bp->b_flags |= B_EINTR;
 1694                         splx(s);
 1695                 } else {
 1696                     if (error) {
 1697                         bp->b_ioflags |= BIO_ERROR;
 1698                         bp->b_error = np->n_error = error;
 1699                         np->n_flag |= NWRITEERR;
 1700                     }
 1701                     bp->b_dirtyoff = bp->b_dirtyend = 0;
 1702                 }
 1703             } else {
 1704                 bp->b_resid = 0;
 1705                 bufdone(bp);
 1706                 return (0);
 1707             }
 1708         }
 1709         bp->b_resid = uiop->uio_resid;
 1710         if (must_commit)
 1711             nfs_clearcommit(vp->v_mount);
 1712         bufdone(bp);
 1713         return (error);
 1714 }
 1715 
 1716 /*
 1717  * Used to aid in handling ftruncate() operations on the NFS client side.
 1718  * Truncation creates a number of special problems for NFS.  We have to
 1719  * throw away VM pages and buffer cache buffers that are beyond EOF, and
 1720  * we have to properly handle VM pages or (potentially dirty) buffers
 1721  * that straddle the truncation point.
 1722  */
 1723 
 1724 int
 1725 nfs_meta_setsize(struct vnode *vp, struct ucred *cred, struct thread *td, u_quad_t nsize)
 1726 {
 1727         struct nfsnode *np = VTONFS(vp);
 1728         u_quad_t tsize = np->n_size;
 1729         int biosize = vp->v_mount->mnt_stat.f_iosize;
 1730         int error = 0;
 1731 
 1732         np->n_size = nsize;
 1733 
 1734         if (np->n_size < tsize) {
 1735                 struct buf *bp;
 1736                 daddr_t lbn;
 1737                 int bufsize;
 1738 
 1739                 /*
 1740                  * vtruncbuf() doesn't get the buffer overlapping the 
 1741                  * truncation point.  We may have a B_DELWRI and/or B_CACHE
 1742                  * buffer that now needs to be truncated.
 1743                  */
 1744                 error = vtruncbuf(vp, cred, td, nsize, biosize);
 1745                 lbn = nsize / biosize;
 1746                 bufsize = nsize & (biosize - 1);
 1747                 bp = nfs_getcacheblk(vp, lbn, bufsize, td);
 1748                 if (!bp)
 1749                         return EINTR;
 1750                 if (bp->b_dirtyoff > bp->b_bcount)
 1751                         bp->b_dirtyoff = bp->b_bcount;
 1752                 if (bp->b_dirtyend > bp->b_bcount)
 1753                         bp->b_dirtyend = bp->b_bcount;
 1754                 bp->b_flags |= B_RELBUF;  /* don't leave garbage around */
 1755                 brelse(bp);
 1756         } else {
 1757                 vnode_pager_setsize(vp, nsize);
 1758         }
 1759         return(error);
 1760 }
 1761 

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