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/6.4/sys/nfsclient/nfs_bio.c 171478 2007-07-17 21:02:08Z jhb $");
   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_enable && !nfs_directio_allow_mmap && 
  109             (np->n_flag & NNONCACHE) && 
  110             (vp->v_type == VREG)) {
  111                 printf("nfs_getpages: called on non-cacheable vnode??\n");
  112                 return VM_PAGER_ERROR;
  113         }
  114 
  115         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  116             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  117                 /* We'll never get here for v4, because we always have fsinfo */
  118                 (void)nfs_fsinfo(nmp, vp, cred, td);
  119         }
  120 
  121         npages = btoc(count);
  122 
  123         /*
  124          * If the requested page is partially valid, just return it and
  125          * allow the pager to zero-out the blanks.  Partially valid pages
  126          * can only occur at the file EOF.
  127          */
  128 
  129         {
  130                 vm_page_t m = pages[ap->a_reqpage];
  131 
  132                 VM_OBJECT_LOCK(object);
  133                 vm_page_lock_queues();
  134                 if (m->valid != 0) {
  135                         /* handled by vm_fault now        */
  136                         /* vm_page_zero_invalid(m, TRUE); */
  137                         for (i = 0; i < npages; ++i) {
  138                                 if (i != ap->a_reqpage)
  139                                         vm_page_free(pages[i]);
  140                         }
  141                         vm_page_unlock_queues();
  142                         VM_OBJECT_UNLOCK(object);
  143                         return(0);
  144                 }
  145                 vm_page_unlock_queues();
  146                 VM_OBJECT_UNLOCK(object);
  147         }
  148 
  149         /*
  150          * We use only the kva address for the buffer, but this is extremely
  151          * convienient and fast.
  152          */
  153         bp = getpbuf(&nfs_pbuf_freecnt);
  154 
  155         kva = (vm_offset_t) bp->b_data;
  156         pmap_qenter(kva, pages, npages);
  157         cnt.v_vnodein++;
  158         cnt.v_vnodepgsin += npages;
  159 
  160         iov.iov_base = (caddr_t) kva;
  161         iov.iov_len = count;
  162         uio.uio_iov = &iov;
  163         uio.uio_iovcnt = 1;
  164         uio.uio_offset = IDX_TO_OFF(pages[0]->pindex);
  165         uio.uio_resid = count;
  166         uio.uio_segflg = UIO_SYSSPACE;
  167         uio.uio_rw = UIO_READ;
  168         uio.uio_td = td;
  169 
  170         error = (nmp->nm_rpcops->nr_readrpc)(vp, &uio, cred);
  171         pmap_qremove(kva, npages);
  172 
  173         relpbuf(bp, &nfs_pbuf_freecnt);
  174 
  175         if (error && (uio.uio_resid == count)) {
  176                 printf("nfs_getpages: error %d\n", error);
  177                 VM_OBJECT_LOCK(object);
  178                 vm_page_lock_queues();
  179                 for (i = 0; i < npages; ++i) {
  180                         if (i != ap->a_reqpage)
  181                                 vm_page_free(pages[i]);
  182                 }
  183                 vm_page_unlock_queues();
  184                 VM_OBJECT_UNLOCK(object);
  185                 return VM_PAGER_ERROR;
  186         }
  187 
  188         /*
  189          * Calculate the number of bytes read and validate only that number
  190          * of bytes.  Note that due to pending writes, size may be 0.  This
  191          * does not mean that the remaining data is invalid!
  192          */
  193 
  194         size = count - uio.uio_resid;
  195         VM_OBJECT_LOCK(object);
  196         vm_page_lock_queues();
  197         for (i = 0, toff = 0; i < npages; i++, toff = nextoff) {
  198                 vm_page_t m;
  199                 nextoff = toff + PAGE_SIZE;
  200                 m = pages[i];
  201 
  202                 if (nextoff <= size) {
  203                         /*
  204                          * Read operation filled an entire page
  205                          */
  206                         m->valid = VM_PAGE_BITS_ALL;
  207                         vm_page_undirty(m);
  208                 } else if (size > toff) {
  209                         /*
  210                          * Read operation filled a partial page.
  211                          */
  212                         m->valid = 0;
  213                         vm_page_set_validclean(m, 0, size - toff);
  214                         /* handled by vm_fault now        */
  215                         /* vm_page_zero_invalid(m, TRUE); */
  216                 } else {
  217                         /*
  218                          * Read operation was short.  If no error occured
  219                          * we may have hit a zero-fill section.   We simply
  220                          * leave valid set to 0.
  221                          */
  222                         ;
  223                 }
  224                 if (i != ap->a_reqpage) {
  225                         /*
  226                          * Whether or not to leave the page activated is up in
  227                          * the air, but we should put the page on a page queue
  228                          * somewhere (it already is in the object).  Result:
  229                          * It appears that emperical results show that
  230                          * deactivating pages is best.
  231                          */
  232 
  233                         /*
  234                          * Just in case someone was asking for this page we
  235                          * now tell them that it is ok to use.
  236                          */
  237                         if (!error) {
  238                                 if (m->flags & PG_WANTED)
  239                                         vm_page_activate(m);
  240                                 else
  241                                         vm_page_deactivate(m);
  242                                 vm_page_wakeup(m);
  243                         } else {
  244                                 vm_page_free(m);
  245                         }
  246                 }
  247         }
  248         vm_page_unlock_queues();
  249         VM_OBJECT_UNLOCK(object);
  250         return 0;
  251 }
  252 
  253 /*
  254  * Vnode op for VM putpages.
  255  */
  256 int
  257 nfs_putpages(struct vop_putpages_args *ap)
  258 {
  259         struct uio uio;
  260         struct iovec iov;
  261         vm_offset_t kva;
  262         struct buf *bp;
  263         int iomode, must_commit, i, error, npages, count;
  264         off_t offset;
  265         int *rtvals;
  266         struct vnode *vp;
  267         struct thread *td;
  268         struct ucred *cred;
  269         struct nfsmount *nmp;
  270         struct nfsnode *np;
  271         vm_page_t *pages;
  272 
  273         GIANT_REQUIRED;
  274 
  275         vp = ap->a_vp;
  276         np = VTONFS(vp);
  277         td = curthread;                         /* XXX */
  278         cred = curthread->td_ucred;             /* XXX */
  279         nmp = VFSTONFS(vp->v_mount);
  280         pages = ap->a_m;
  281         count = ap->a_count;
  282         rtvals = ap->a_rtvals;
  283         npages = btoc(count);
  284         offset = IDX_TO_OFF(pages[0]->pindex);
  285 
  286         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  287             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  288                 (void)nfs_fsinfo(nmp, vp, cred, td);
  289         }
  290 
  291         if (nfs_directio_enable && !nfs_directio_allow_mmap && 
  292             (np->n_flag & NNONCACHE) && (vp->v_type == VREG))
  293                 printf("nfs_putpages: called on noncache-able vnode??\n");
  294 
  295         for (i = 0; i < npages; i++)
  296                 rtvals[i] = VM_PAGER_AGAIN;
  297 
  298         /*
  299          * When putting pages, do not extend file past EOF.
  300          */
  301 
  302         if (offset + count > np->n_size) {
  303                 count = np->n_size - offset;
  304                 if (count < 0)
  305                         count = 0;
  306         }
  307 
  308         /*
  309          * We use only the kva address for the buffer, but this is extremely
  310          * convienient and fast.
  311          */
  312         bp = getpbuf(&nfs_pbuf_freecnt);
  313 
  314         kva = (vm_offset_t) bp->b_data;
  315         pmap_qenter(kva, pages, npages);
  316         cnt.v_vnodeout++;
  317         cnt.v_vnodepgsout += count;
  318 
  319         iov.iov_base = (caddr_t) kva;
  320         iov.iov_len = count;
  321         uio.uio_iov = &iov;
  322         uio.uio_iovcnt = 1;
  323         uio.uio_offset = offset;
  324         uio.uio_resid = count;
  325         uio.uio_segflg = UIO_SYSSPACE;
  326         uio.uio_rw = UIO_WRITE;
  327         uio.uio_td = td;
  328 
  329         if ((ap->a_sync & VM_PAGER_PUT_SYNC) == 0)
  330             iomode = NFSV3WRITE_UNSTABLE;
  331         else
  332             iomode = NFSV3WRITE_FILESYNC;
  333 
  334         error = (nmp->nm_rpcops->nr_writerpc)(vp, &uio, cred, &iomode, &must_commit);
  335 
  336         pmap_qremove(kva, npages);
  337         relpbuf(bp, &nfs_pbuf_freecnt);
  338 
  339         if (!error) {
  340                 int nwritten = round_page(count - uio.uio_resid) / PAGE_SIZE;
  341                 for (i = 0; i < nwritten; i++) {
  342                         rtvals[i] = VM_PAGER_OK;
  343                         vm_page_undirty(pages[i]);
  344                 }
  345                 if (must_commit) {
  346                         nfs_clearcommit(vp->v_mount);
  347                 }
  348         }
  349         return rtvals[0];
  350 }
  351 
  352 /*
  353  * Vnode op for read using bio
  354  */
  355 int
  356 nfs_bioread(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred)
  357 {
  358         struct nfsnode *np = VTONFS(vp);
  359         int biosize, i;
  360         struct buf *bp, *rabp;
  361         struct vattr vattr;
  362         struct thread *td;
  363         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  364         daddr_t lbn, rabn;
  365         int bcount;
  366         int seqcount;
  367         int nra, error = 0, n = 0, on = 0;
  368 
  369 #ifdef DIAGNOSTIC
  370         if (uio->uio_rw != UIO_READ)
  371                 panic("nfs_read mode");
  372 #endif
  373         if (uio->uio_resid == 0)
  374                 return (0);
  375         if (uio->uio_offset < 0)        /* XXX VDIR cookies can be negative */
  376                 return (EINVAL);
  377         td = uio->uio_td;
  378 
  379         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  380             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0)
  381                 (void)nfs_fsinfo(nmp, vp, cred, td);
  382         if (vp->v_type != VDIR &&
  383             (uio->uio_offset + uio->uio_resid) > nmp->nm_maxfilesize)
  384                 return (EFBIG);
  385 
  386         if (nfs_directio_enable && (ioflag & IO_DIRECT) && (vp->v_type == VREG))
  387                 /* No caching/ no readaheads. Just read data into the user buffer */
  388                 return nfs_readrpc(vp, uio, cred);
  389 
  390         biosize = vp->v_mount->mnt_stat.f_iosize;
  391         seqcount = (int)((off_t)(ioflag >> IO_SEQSHIFT) * biosize / BKVASIZE);
  392         /*
  393          * For nfs, cache consistency can only be maintained approximately.
  394          * Although RFC1094 does not specify the criteria, the following is
  395          * believed to be compatible with the reference port.
  396          * For nfs:
  397          * If the file's modify time on the server has changed since the
  398          * last read rpc or you have written to the file,
  399          * you may have lost data cache consistency with the
  400          * server, so flush all of the file's data out of the cache.
  401          * Then force a getattr rpc to ensure that you have up to date
  402          * attributes.
  403          * NB: This implies that cache data can be read when up to
  404          * NFS_ATTRTIMEO seconds out of date. If you find that you need current
  405          * attributes this could be forced by setting n_attrstamp to 0 before
  406          * the VOP_GETATTR() call.
  407          */
  408         if (np->n_flag & NMODIFIED) {
  409                 if (vp->v_type != VREG) {
  410                         if (vp->v_type != VDIR)
  411                                 panic("nfs: bioread, not dir");
  412                         (nmp->nm_rpcops->nr_invaldir)(vp);
  413                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  414                         if (error)
  415                                 return (error);
  416                 }
  417                 np->n_attrstamp = 0;
  418                 error = VOP_GETATTR(vp, &vattr, cred, td);
  419                 if (error)
  420                         return (error);
  421                 np->n_mtime = vattr.va_mtime;
  422         } else {
  423                 error = VOP_GETATTR(vp, &vattr, cred, td);
  424                 if (error)
  425                         return (error);
  426                 if ((np->n_flag & NSIZECHANGED)
  427                     || (NFS_TIMESPEC_COMPARE(&np->n_mtime, &vattr.va_mtime))) {
  428                         if (vp->v_type == VDIR)
  429                                 (nmp->nm_rpcops->nr_invaldir)(vp);
  430                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  431                         if (error)
  432                                 return (error);
  433                         np->n_mtime = vattr.va_mtime;
  434                         np->n_flag &= ~NSIZECHANGED;
  435                 }
  436         }
  437         do {
  438             switch (vp->v_type) {
  439             case VREG:
  440                 nfsstats.biocache_reads++;
  441                 lbn = uio->uio_offset / biosize;
  442                 on = uio->uio_offset & (biosize - 1);
  443 
  444                 /*
  445                  * Start the read ahead(s), as required.
  446                  * The readahead is kicked off only if sequential access
  447                  * is detected, based on the readahead hint (ra_expect_lbn).
  448                  */
  449                 if (nmp->nm_readahead > 0 && np->ra_expect_lbn == lbn) {
  450                     for (nra = 0; nra < nmp->nm_readahead && nra < seqcount &&
  451                         (off_t)(lbn + 1 + nra) * biosize < np->n_size; nra++) {
  452                         rabn = lbn + 1 + nra;
  453                         if (incore(&vp->v_bufobj, rabn) == NULL) {
  454                             rabp = nfs_getcacheblk(vp, rabn, biosize, td);
  455                             if (!rabp) {
  456                                 error = nfs_sigintr(nmp, NULL, td);
  457                                 return (error ? error : EINTR);
  458                             }
  459                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  460                                 rabp->b_flags |= B_ASYNC;
  461                                 rabp->b_iocmd = BIO_READ;
  462                                 vfs_busy_pages(rabp, 0);
  463                                 if (nfs_asyncio(nmp, rabp, cred, td)) {
  464                                     rabp->b_flags |= B_INVAL;
  465                                     rabp->b_ioflags |= BIO_ERROR;
  466                                     vfs_unbusy_pages(rabp);
  467                                     brelse(rabp);
  468                                     break;
  469                                 }
  470                             } else {
  471                                 brelse(rabp);
  472                             }
  473                         }
  474                     }
  475                     np->ra_expect_lbn = lbn + 1;
  476                 }
  477 
  478                 /*
  479                  * Obtain the buffer cache block.  Figure out the buffer size
  480                  * when we are at EOF.  If we are modifying the size of the
  481                  * buffer based on an EOF condition we need to hold
  482                  * nfs_rslock() through obtaining the buffer to prevent
  483                  * a potential writer-appender from messing with n_size.
  484                  * Otherwise we may accidently truncate the buffer and
  485                  * lose dirty data.
  486                  *
  487                  * Note that bcount is *not* DEV_BSIZE aligned.
  488                  */
  489 
  490 again:
  491                 bcount = biosize;
  492                 if ((off_t)lbn * biosize >= np->n_size) {
  493                         bcount = 0;
  494                 } else if ((off_t)(lbn + 1) * biosize > np->n_size) {
  495                         bcount = np->n_size - (off_t)lbn * biosize;
  496                 }
  497                 if (bcount != biosize) {
  498                         switch(nfs_rslock(np, td)) {
  499                         case ENOLCK:
  500                                 goto again;
  501                                 /* not reached */
  502                         case EIO:
  503                                 return (EIO);
  504                         case EINTR:
  505                         case ERESTART:
  506                                 return(EINTR);
  507                                 /* not reached */
  508                         default:
  509                                 break;
  510                         }
  511                 }
  512 
  513                 bp = nfs_getcacheblk(vp, lbn, bcount, td);
  514 
  515                 if (bcount != biosize)
  516                         nfs_rsunlock(np, td);
  517                 if (!bp) {
  518                         error = nfs_sigintr(nmp, NULL, td);
  519                         return (error ? error : EINTR);
  520                 }
  521 
  522                 /*
  523                  * If B_CACHE is not set, we must issue the read.  If this
  524                  * fails, we return an error.
  525                  */
  526 
  527                 if ((bp->b_flags & B_CACHE) == 0) {
  528                     bp->b_iocmd = BIO_READ;
  529                     vfs_busy_pages(bp, 0);
  530                     error = nfs_doio(vp, bp, cred, td);
  531                     if (error) {
  532                         brelse(bp);
  533                         return (error);
  534                     }
  535                 }
  536 
  537                 /*
  538                  * on is the offset into the current bp.  Figure out how many
  539                  * bytes we can copy out of the bp.  Note that bcount is
  540                  * NOT DEV_BSIZE aligned.
  541                  *
  542                  * Then figure out how many bytes we can copy into the uio.
  543                  */
  544 
  545                 n = 0;
  546                 if (on < bcount)
  547                         n = min((unsigned)(bcount - on), uio->uio_resid);
  548                 break;
  549             case VLNK:
  550                 nfsstats.biocache_readlinks++;
  551                 bp = nfs_getcacheblk(vp, (daddr_t)0, NFS_MAXPATHLEN, td);
  552                 if (!bp) {
  553                         error = nfs_sigintr(nmp, NULL, td);
  554                         return (error ? error : EINTR);
  555                 }
  556                 if ((bp->b_flags & B_CACHE) == 0) {
  557                     bp->b_iocmd = BIO_READ;
  558                     vfs_busy_pages(bp, 0);
  559                     error = nfs_doio(vp, bp, cred, td);
  560                     if (error) {
  561                         bp->b_ioflags |= BIO_ERROR;
  562                         brelse(bp);
  563                         return (error);
  564                     }
  565                 }
  566                 n = min(uio->uio_resid, NFS_MAXPATHLEN - bp->b_resid);
  567                 on = 0;
  568                 break;
  569             case VDIR:
  570                 nfsstats.biocache_readdirs++;
  571                 if (np->n_direofoffset
  572                     && uio->uio_offset >= np->n_direofoffset) {
  573                     return (0);
  574                 }
  575                 lbn = (uoff_t)uio->uio_offset / NFS_DIRBLKSIZ;
  576                 on = uio->uio_offset & (NFS_DIRBLKSIZ - 1);
  577                 bp = nfs_getcacheblk(vp, lbn, NFS_DIRBLKSIZ, td);
  578                 if (!bp) {
  579                     error = nfs_sigintr(nmp, NULL, td);
  580                     return (error ? error : EINTR);
  581                 }
  582                 if ((bp->b_flags & B_CACHE) == 0) {
  583                     bp->b_iocmd = BIO_READ;
  584                     vfs_busy_pages(bp, 0);
  585                     error = nfs_doio(vp, bp, cred, td);
  586                     if (error) {
  587                             brelse(bp);
  588                     }
  589                     while (error == NFSERR_BAD_COOKIE) {
  590                         (nmp->nm_rpcops->nr_invaldir)(vp);
  591                         error = nfs_vinvalbuf(vp, 0, td, 1);
  592                         /*
  593                          * Yuck! The directory has been modified on the
  594                          * server. The only way to get the block is by
  595                          * reading from the beginning to get all the
  596                          * offset cookies.
  597                          *
  598                          * Leave the last bp intact unless there is an error.
  599                          * Loop back up to the while if the error is another
  600                          * NFSERR_BAD_COOKIE (double yuch!).
  601                          */
  602                         for (i = 0; i <= lbn && !error; i++) {
  603                             if (np->n_direofoffset
  604                                 && (i * NFS_DIRBLKSIZ) >= np->n_direofoffset)
  605                                     return (0);
  606                             bp = nfs_getcacheblk(vp, i, NFS_DIRBLKSIZ, td);
  607                             if (!bp) {
  608                                 error = nfs_sigintr(nmp, NULL, td);
  609                                 return (error ? error : EINTR);
  610                             }
  611                             if ((bp->b_flags & B_CACHE) == 0) {
  612                                     bp->b_iocmd = BIO_READ;
  613                                     vfs_busy_pages(bp, 0);
  614                                     error = nfs_doio(vp, bp, cred, td);
  615                                     /*
  616                                      * no error + B_INVAL == directory EOF,
  617                                      * use the block.
  618                                      */
  619                                     if (error == 0 && (bp->b_flags & B_INVAL))
  620                                             break;
  621                             }
  622                             /*
  623                              * An error will throw away the block and the
  624                              * for loop will break out.  If no error and this
  625                              * is not the block we want, we throw away the
  626                              * block and go for the next one via the for loop.
  627                              */
  628                             if (error || i < lbn)
  629                                     brelse(bp);
  630                         }
  631                     }
  632                     /*
  633                      * The above while is repeated if we hit another cookie
  634                      * error.  If we hit an error and it wasn't a cookie error,
  635                      * we give up.
  636                      */
  637                     if (error)
  638                             return (error);
  639                 }
  640 
  641                 /*
  642                  * If not eof and read aheads are enabled, start one.
  643                  * (You need the current block first, so that you have the
  644                  *  directory offset cookie of the next block.)
  645                  */
  646                 if (nmp->nm_readahead > 0 &&
  647                     (bp->b_flags & B_INVAL) == 0 &&
  648                     (np->n_direofoffset == 0 ||
  649                     (lbn + 1) * NFS_DIRBLKSIZ < np->n_direofoffset) &&
  650                     incore(&vp->v_bufobj, lbn + 1) == NULL) {
  651                         rabp = nfs_getcacheblk(vp, lbn + 1, NFS_DIRBLKSIZ, td);
  652                         if (rabp) {
  653                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  654                                 rabp->b_flags |= B_ASYNC;
  655                                 rabp->b_iocmd = BIO_READ;
  656                                 vfs_busy_pages(rabp, 0);
  657                                 if (nfs_asyncio(nmp, rabp, cred, td)) {
  658                                     rabp->b_flags |= B_INVAL;
  659                                     rabp->b_ioflags |= BIO_ERROR;
  660                                     vfs_unbusy_pages(rabp);
  661                                     brelse(rabp);
  662                                 }
  663                             } else {
  664                                 brelse(rabp);
  665                             }
  666                         }
  667                 }
  668                 /*
  669                  * Unlike VREG files, whos buffer size ( bp->b_bcount ) is
  670                  * chopped for the EOF condition, we cannot tell how large
  671                  * NFS directories are going to be until we hit EOF.  So
  672                  * an NFS directory buffer is *not* chopped to its EOF.  Now,
  673                  * it just so happens that b_resid will effectively chop it
  674                  * to EOF.  *BUT* this information is lost if the buffer goes
  675                  * away and is reconstituted into a B_CACHE state ( due to
  676                  * being VMIO ) later.  So we keep track of the directory eof
  677                  * in np->n_direofoffset and chop it off as an extra step
  678                  * right here.
  679                  */
  680                 n = lmin(uio->uio_resid, NFS_DIRBLKSIZ - bp->b_resid - on);
  681                 if (np->n_direofoffset && n > np->n_direofoffset - uio->uio_offset)
  682                         n = np->n_direofoffset - uio->uio_offset;
  683                 break;
  684             default:
  685                 printf(" nfs_bioread: type %x unexpected\n", vp->v_type);
  686                 bp = NULL;
  687                 break;
  688             };
  689 
  690             if (n > 0) {
  691                     error = uiomove(bp->b_data + on, (int)n, uio);
  692             }
  693             if (vp->v_type == VLNK)
  694                 n = 0;
  695             if (bp != NULL)
  696                 brelse(bp);
  697         } while (error == 0 && uio->uio_resid > 0 && n > 0);
  698         return (error);
  699 }
  700 
  701 /*
  702  * The NFS write path cannot handle iovecs with len > 1. So we need to 
  703  * break up iovecs accordingly (restricting them to wsize).
  704  * For the SYNC case, we can do this with 1 copy (user buffer -> mbuf). 
  705  * For the ASYNC case, 2 copies are needed. The first a copy from the 
  706  * user buffer to a staging buffer and then a second copy from the staging
  707  * buffer to mbufs. This can be optimized by copying from the user buffer
  708  * directly into mbufs and passing the chain down, but that requires a 
  709  * fair amount of re-working of the relevant codepaths (and can be done
  710  * later).
  711  */
  712 static int
  713 nfs_directio_write(vp, uiop, cred, ioflag)
  714         struct vnode *vp;
  715         struct uio *uiop;
  716         struct ucred *cred;
  717         int ioflag;
  718 {
  719         int error;
  720         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  721         struct thread *td = uiop->uio_td;
  722         int size;
  723 
  724         if (ioflag & IO_SYNC) {
  725                 int iomode, must_commit;
  726                 struct uio uio;
  727                 struct iovec iov;
  728 do_sync:
  729                 while (uiop->uio_resid > 0) {
  730                         size = min(uiop->uio_resid, nmp->nm_wsize);
  731                         size = min(uiop->uio_iov->iov_len, size);
  732                         iov.iov_base = uiop->uio_iov->iov_base;
  733                         iov.iov_len = size;
  734                         uio.uio_iov = &iov;
  735                         uio.uio_iovcnt = 1;
  736                         uio.uio_offset = uiop->uio_offset;
  737                         uio.uio_resid = size;
  738                         uio.uio_segflg = UIO_USERSPACE;
  739                         uio.uio_rw = UIO_WRITE;
  740                         uio.uio_td = td;
  741                         iomode = NFSV3WRITE_FILESYNC;
  742                         error = (nmp->nm_rpcops->nr_writerpc)(vp, &uio, cred, 
  743                                                       &iomode, &must_commit);
  744                         KASSERT((must_commit == 0), 
  745                                 ("nfs_directio_write: Did not commit write"));
  746                         if (error)
  747                                 return (error);
  748                         uiop->uio_offset += size;
  749                         uiop->uio_resid -= size;
  750                         if (uiop->uio_iov->iov_len <= size) {
  751                                 uiop->uio_iovcnt--;
  752                                 uiop->uio_iov++;
  753                         } else {
  754                                 uiop->uio_iov->iov_base = 
  755                                         (char *)uiop->uio_iov->iov_base + size;
  756                                 uiop->uio_iov->iov_len -= size;
  757                         }
  758                 }
  759         } else {
  760                 struct uio *t_uio;
  761                 struct iovec *t_iov;
  762                 struct buf *bp;
  763                 
  764                 /*
  765                  * Break up the write into blocksize chunks and hand these
  766                  * over to nfsiod's for write back.
  767                  * Unfortunately, this incurs a copy of the data. Since 
  768                  * the user could modify the buffer before the write is 
  769                  * initiated.
  770                  * 
  771                  * The obvious optimization here is that one of the 2 copies
  772                  * in the async write path can be eliminated by copying the
  773                  * data here directly into mbufs and passing the mbuf chain
  774                  * down. But that will require a fair amount of re-working
  775                  * of the code and can be done if there's enough interest
  776                  * in NFS directio access.
  777                  */
  778                 while (uiop->uio_resid > 0) {
  779                         size = min(uiop->uio_resid, nmp->nm_wsize);
  780                         size = min(uiop->uio_iov->iov_len, size);
  781                         bp = getpbuf(&nfs_pbuf_freecnt);
  782                         t_uio = malloc(sizeof(struct uio), M_NFSDIRECTIO, M_WAITOK);
  783                         t_iov = malloc(sizeof(struct iovec), M_NFSDIRECTIO, M_WAITOK);
  784                         t_iov->iov_base = malloc(size, M_NFSDIRECTIO, M_WAITOK);
  785                         t_iov->iov_len = size;
  786                         t_uio->uio_iov = t_iov;
  787                         t_uio->uio_iovcnt = 1;
  788                         t_uio->uio_offset = uiop->uio_offset;
  789                         t_uio->uio_resid = size;
  790                         t_uio->uio_segflg = UIO_SYSSPACE;
  791                         t_uio->uio_rw = UIO_WRITE;
  792                         t_uio->uio_td = td;
  793                         bcopy(uiop->uio_iov->iov_base, t_iov->iov_base, size);
  794                         bp->b_flags |= B_DIRECT;
  795                         bp->b_iocmd = BIO_WRITE;
  796                         if (cred != NOCRED) {
  797                                 crhold(cred);
  798                                 bp->b_wcred = cred;
  799                         } else 
  800                                 bp->b_wcred = NOCRED;                   
  801                         bp->b_caller1 = (void *)t_uio;
  802                         bp->b_vp = 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                                 bp->b_vp = NULL;
  809                                 relpbuf(bp, &nfs_pbuf_freecnt);
  810                                 if (error == EINTR)
  811                                         return (error);
  812                                 goto do_sync;
  813                         }
  814                         uiop->uio_offset += size;
  815                         uiop->uio_resid -= size;
  816                         if (uiop->uio_iov->iov_len <= size) {
  817                                 uiop->uio_iovcnt--;
  818                                 uiop->uio_iov++;
  819                         } else {
  820                                 uiop->uio_iov->iov_base = 
  821                                         (char *)uiop->uio_iov->iov_base + size;
  822                                 uiop->uio_iov->iov_len -= size;
  823                         }
  824                 }
  825         }
  826         return (0);
  827 }
  828 
  829 /*
  830  * Vnode op for write using bio
  831  */
  832 int
  833 nfs_write(struct vop_write_args *ap)
  834 {
  835         int biosize;
  836         struct uio *uio = ap->a_uio;
  837         struct thread *td = uio->uio_td;
  838         struct vnode *vp = ap->a_vp;
  839         struct nfsnode *np = VTONFS(vp);
  840         struct ucred *cred = ap->a_cred;
  841         int ioflag = ap->a_ioflag;
  842         struct buf *bp;
  843         struct vattr vattr;
  844         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  845         daddr_t lbn;
  846         int bcount;
  847         int n, on, error = 0;
  848         int haverslock = 0;
  849         struct proc *p = td?td->td_proc:NULL;
  850 
  851         GIANT_REQUIRED;
  852 
  853 #ifdef DIAGNOSTIC
  854         if (uio->uio_rw != UIO_WRITE)
  855                 panic("nfs_write mode");
  856         if (uio->uio_segflg == UIO_USERSPACE && uio->uio_td != curthread)
  857                 panic("nfs_write proc");
  858 #endif
  859         if (vp->v_type != VREG)
  860                 return (EIO);
  861         if (np->n_flag & NWRITEERR) {
  862                 np->n_flag &= ~NWRITEERR;
  863                 return (np->n_error);
  864         }
  865         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  866             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0)
  867                 (void)nfs_fsinfo(nmp, vp, cred, td);
  868 
  869         /*
  870          * Synchronously flush pending buffers if we are in synchronous
  871          * mode or if we are appending.
  872          */
  873         if (ioflag & (IO_APPEND | IO_SYNC)) {
  874                 if (np->n_flag & NMODIFIED) {
  875 #ifdef notyet /* Needs matching nonblock semantics elsewhere, too. */
  876                         /*
  877                          * Require non-blocking, synchronous writes to
  878                          * dirty files to inform the program it needs
  879                          * to fsync(2) explicitly.
  880                          */
  881                         if (ioflag & IO_NDELAY)
  882                                 return (EAGAIN);
  883 #endif
  884 flush_and_restart:
  885                         np->n_attrstamp = 0;
  886                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  887                         if (error)
  888                                 return (error);
  889                 }
  890         }
  891 
  892         /*
  893          * If IO_APPEND then load uio_offset.  We restart here if we cannot
  894          * get the append lock.
  895          */
  896 restart:
  897         if (ioflag & IO_APPEND) {
  898                 np->n_attrstamp = 0;
  899                 error = VOP_GETATTR(vp, &vattr, cred, td);
  900                 if (error)
  901                         return (error);
  902                 uio->uio_offset = np->n_size;
  903         }
  904 
  905         if (uio->uio_offset < 0)
  906                 return (EINVAL);
  907         if ((uio->uio_offset + uio->uio_resid) > nmp->nm_maxfilesize)
  908                 return (EFBIG);
  909         if (uio->uio_resid == 0)
  910                 return (0);
  911 
  912         if (nfs_directio_enable && (ioflag & IO_DIRECT) && vp->v_type == VREG)
  913                 return nfs_directio_write(vp, uio, cred, ioflag);
  914 
  915         /*
  916          * We need to obtain the rslock if we intend to modify np->n_size
  917          * in order to guarentee the append point with multiple contending
  918          * writers, to guarentee that no other appenders modify n_size
  919          * while we are trying to obtain a truncated buffer (i.e. to avoid
  920          * accidently truncating data written by another appender due to
  921          * the race), and to ensure that the buffer is populated prior to
  922          * our extending of the file.  We hold rslock through the entire
  923          * operation.
  924          *
  925          * Note that we do not synchronize the case where someone truncates
  926          * the file while we are appending to it because attempting to lock
  927          * this case may deadlock other parts of the system unexpectedly.
  928          */
  929         if ((ioflag & IO_APPEND) ||
  930             uio->uio_offset + uio->uio_resid > np->n_size) {
  931                 switch(nfs_rslock(np, td)) {
  932                 case ENOLCK:
  933                         goto restart;
  934                         /* not reached */
  935                 case EIO:
  936                         return (EIO);
  937                 case EINTR:
  938                 case ERESTART:
  939                         return(EINTR);
  940                         /* not reached */
  941                 default:
  942                         break;
  943                 }
  944                 haverslock = 1;
  945         }
  946 
  947         /*
  948          * Maybe this should be above the vnode op call, but so long as
  949          * file servers have no limits, i don't think it matters
  950          */
  951         if (p != NULL) {
  952                 PROC_LOCK(p);
  953                 if (uio->uio_offset + uio->uio_resid >
  954                     lim_cur(p, RLIMIT_FSIZE)) {
  955                         psignal(p, SIGXFSZ);
  956                         PROC_UNLOCK(p);
  957                         if (haverslock)
  958                                 nfs_rsunlock(np, td);
  959                         return (EFBIG);
  960                 }
  961                 PROC_UNLOCK(p);
  962         }
  963 
  964         biosize = vp->v_mount->mnt_stat.f_iosize;
  965         /*
  966          * Find all of this file's B_NEEDCOMMIT buffers.  If our writes
  967          * would exceed the local maximum per-file write commit size when
  968          * combined with those, we must decide whether to flush,
  969          * go synchronous, or return error.  We don't bother checking
  970          * IO_UNIT -- we just make all writes atomic anyway, as there's
  971          * no point optimizing for something that really won't ever happen.
  972          */
  973         if (!(ioflag & IO_SYNC)) {
  974                 int needrestart = 0;
  975                 if (nmp->nm_wcommitsize < uio->uio_resid) {
  976                         /*
  977                          * If this request could not possibly be completed
  978                          * without exceeding the maximum outstanding write
  979                          * commit size, see if we can convert it into a
  980                          * synchronous write operation.
  981                          */
  982                         if (ioflag & IO_NDELAY)
  983                                 return (EAGAIN);
  984                         ioflag |= IO_SYNC;
  985                         if (np->n_flag & NMODIFIED)
  986                                 needrestart = 1;
  987                 } else if (np->n_flag & NMODIFIED) {
  988                         int wouldcommit = 0;
  989                         BO_LOCK(&vp->v_bufobj);
  990                         if (vp->v_bufobj.bo_dirty.bv_cnt != 0) {
  991                                 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd,
  992                                     b_bobufs) {
  993                                         if (bp->b_flags & B_NEEDCOMMIT)
  994                                                 wouldcommit += bp->b_bcount;
  995                                 }
  996                         }
  997                         BO_UNLOCK(&vp->v_bufobj);
  998                         /*
  999                          * Since we're not operating synchronously and
 1000                          * bypassing the buffer cache, we are in a commit
 1001                          * and holding all of these buffers whether
 1002                          * transmitted or not.  If not limited, this
 1003                          * will lead to the buffer cache deadlocking,
 1004                          * as no one else can flush our uncommitted buffers.
 1005                          */
 1006                         wouldcommit += uio->uio_resid;
 1007                         /*
 1008                          * If we would initially exceed the maximum
 1009                          * outstanding write commit size, flush and restart.
 1010                          */
 1011                         if (wouldcommit > nmp->nm_wcommitsize)
 1012                                 needrestart = 1;
 1013                 }
 1014                 if (needrestart) {
 1015                         if (haverslock) {
 1016                                 nfs_rsunlock(np, td);
 1017                                 haverslock = 0;
 1018                         }
 1019                         goto flush_and_restart;
 1020                 }
 1021         }
 1022 
 1023         do {
 1024                 nfsstats.biocache_writes++;
 1025                 lbn = uio->uio_offset / biosize;
 1026                 on = uio->uio_offset & (biosize-1);
 1027                 n = min((unsigned)(biosize - on), uio->uio_resid);
 1028 again:
 1029                 /*
 1030                  * Handle direct append and file extension cases, calculate
 1031                  * unaligned buffer size.
 1032                  */
 1033 
 1034                 if (uio->uio_offset == np->n_size && n) {
 1035                         /*
 1036                          * Get the buffer (in its pre-append state to maintain
 1037                          * B_CACHE if it was previously set).  Resize the
 1038                          * nfsnode after we have locked the buffer to prevent
 1039                          * readers from reading garbage.
 1040                          */
 1041                         bcount = on;
 1042                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1043 
 1044                         if (bp != NULL) {
 1045                                 long save;
 1046 
 1047                                 np->n_size = uio->uio_offset + n;
 1048                                 np->n_flag |= NMODIFIED;
 1049                                 vnode_pager_setsize(vp, np->n_size);
 1050 
 1051                                 save = bp->b_flags & B_CACHE;
 1052                                 bcount += n;
 1053                                 allocbuf(bp, bcount);
 1054                                 bp->b_flags |= save;
 1055                         }
 1056                 } else {
 1057                         /*
 1058                          * Obtain the locked cache block first, and then
 1059                          * adjust the file's size as appropriate.
 1060                          */
 1061                         bcount = on + n;
 1062                         if ((off_t)lbn * biosize + bcount < np->n_size) {
 1063                                 if ((off_t)(lbn + 1) * biosize < np->n_size)
 1064                                         bcount = biosize;
 1065                                 else
 1066                                         bcount = np->n_size - (off_t)lbn * biosize;
 1067                         }
 1068                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1069                         if (uio->uio_offset + n > np->n_size) {
 1070                                 np->n_size = uio->uio_offset + n;
 1071                                 np->n_flag |= NMODIFIED;
 1072                                 vnode_pager_setsize(vp, np->n_size);
 1073                         }
 1074                 }
 1075 
 1076                 if (!bp) {
 1077                         error = nfs_sigintr(nmp, NULL, td);
 1078                         if (!error)
 1079                                 error = EINTR;
 1080                         break;
 1081                 }
 1082 
 1083                 /*
 1084                  * Issue a READ if B_CACHE is not set.  In special-append
 1085                  * mode, B_CACHE is based on the buffer prior to the write
 1086                  * op and is typically set, avoiding the read.  If a read
 1087                  * is required in special append mode, the server will
 1088                  * probably send us a short-read since we extended the file
 1089                  * on our end, resulting in b_resid == 0 and, thusly,
 1090                  * B_CACHE getting set.
 1091                  *
 1092                  * We can also avoid issuing the read if the write covers
 1093                  * the entire buffer.  We have to make sure the buffer state
 1094                  * is reasonable in this case since we will not be initiating
 1095                  * I/O.  See the comments in kern/vfs_bio.c's getblk() for
 1096                  * more information.
 1097                  *
 1098                  * B_CACHE may also be set due to the buffer being cached
 1099                  * normally.
 1100                  */
 1101 
 1102                 if (on == 0 && n == bcount) {
 1103                         bp->b_flags |= B_CACHE;
 1104                         bp->b_flags &= ~B_INVAL;
 1105                         bp->b_ioflags &= ~BIO_ERROR;
 1106                 }
 1107 
 1108                 if ((bp->b_flags & B_CACHE) == 0) {
 1109                         bp->b_iocmd = BIO_READ;
 1110                         vfs_busy_pages(bp, 0);
 1111                         error = nfs_doio(vp, bp, cred, td);
 1112                         if (error) {
 1113                                 brelse(bp);
 1114                                 break;
 1115                         }
 1116                 }
 1117                 if (bp->b_wcred == NOCRED)
 1118                         bp->b_wcred = crhold(cred);
 1119                 np->n_flag |= NMODIFIED;
 1120 
 1121                 /*
 1122                  * If dirtyend exceeds file size, chop it down.  This should
 1123                  * not normally occur but there is an append race where it
 1124                  * might occur XXX, so we log it.
 1125                  *
 1126                  * If the chopping creates a reverse-indexed or degenerate
 1127                  * situation with dirtyoff/end, we 0 both of them.
 1128                  */
 1129 
 1130                 if (bp->b_dirtyend > bcount) {
 1131                         printf("NFS append race @%lx:%d\n",
 1132                             (long)bp->b_blkno * DEV_BSIZE,
 1133                             bp->b_dirtyend - bcount);
 1134                         bp->b_dirtyend = bcount;
 1135                 }
 1136 
 1137                 if (bp->b_dirtyoff >= bp->b_dirtyend)
 1138                         bp->b_dirtyoff = bp->b_dirtyend = 0;
 1139 
 1140                 /*
 1141                  * If the new write will leave a contiguous dirty
 1142                  * area, just update the b_dirtyoff and b_dirtyend,
 1143                  * otherwise force a write rpc of the old dirty area.
 1144                  *
 1145                  * While it is possible to merge discontiguous writes due to
 1146                  * our having a B_CACHE buffer ( and thus valid read data
 1147                  * for the hole), we don't because it could lead to
 1148                  * significant cache coherency problems with multiple clients,
 1149                  * especially if locking is implemented later on.
 1150                  *
 1151                  * as an optimization we could theoretically maintain
 1152                  * a linked list of discontinuous areas, but we would still
 1153                  * have to commit them separately so there isn't much
 1154                  * advantage to it except perhaps a bit of asynchronization.
 1155                  */
 1156 
 1157                 if (bp->b_dirtyend > 0 &&
 1158                     (on > bp->b_dirtyend || (on + n) < bp->b_dirtyoff)) {
 1159                         if (bwrite(bp) == EINTR) {
 1160                                 error = EINTR;
 1161                                 break;
 1162                         }
 1163                         goto again;
 1164                 }
 1165 
 1166                 error = uiomove((char *)bp->b_data + on, n, uio);
 1167 
 1168                 /*
 1169                  * Since this block is being modified, it must be written
 1170                  * again and not just committed.  Since write clustering does
 1171                  * not work for the stage 1 data write, only the stage 2
 1172                  * commit rpc, we have to clear B_CLUSTEROK as well.
 1173                  */
 1174                 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1175 
 1176                 if (error) {
 1177                         bp->b_ioflags |= BIO_ERROR;
 1178                         brelse(bp);
 1179                         break;
 1180                 }
 1181 
 1182                 /*
 1183                  * Only update dirtyoff/dirtyend if not a degenerate
 1184                  * condition.
 1185                  */
 1186                 if (n) {
 1187                         if (bp->b_dirtyend > 0) {
 1188                                 bp->b_dirtyoff = min(on, bp->b_dirtyoff);
 1189                                 bp->b_dirtyend = max((on + n), bp->b_dirtyend);
 1190                         } else {
 1191                                 bp->b_dirtyoff = on;
 1192                                 bp->b_dirtyend = on + n;
 1193                         }
 1194                         vfs_bio_set_validclean(bp, on, n);
 1195                 }
 1196 
 1197                 /*
 1198                  * If IO_SYNC do bwrite().
 1199                  *
 1200                  * IO_INVAL appears to be unused.  The idea appears to be
 1201                  * to turn off caching in this case.  Very odd.  XXX
 1202                  */
 1203                 if ((ioflag & IO_SYNC)) {
 1204                         if (ioflag & IO_INVAL)
 1205                                 bp->b_flags |= B_NOCACHE;
 1206                         error = bwrite(bp);
 1207                         if (error)
 1208                                 break;
 1209                 } else if ((n + on) == biosize) {
 1210                         bp->b_flags |= B_ASYNC;
 1211                         (void) (nmp->nm_rpcops->nr_writebp)(bp, 0, 0);
 1212                 } else {
 1213                         bdwrite(bp);
 1214                 }
 1215         } while (uio->uio_resid > 0 && n > 0);
 1216 
 1217         if (haverslock)
 1218                 nfs_rsunlock(np, td);
 1219 
 1220         return (error);
 1221 }
 1222 
 1223 /*
 1224  * Get an nfs cache block.
 1225  *
 1226  * Allocate a new one if the block isn't currently in the cache
 1227  * and return the block marked busy. If the calling process is
 1228  * interrupted by a signal for an interruptible mount point, return
 1229  * NULL.
 1230  *
 1231  * The caller must carefully deal with the possible B_INVAL state of
 1232  * the buffer.  nfs_doio() clears B_INVAL (and nfs_asyncio() clears it
 1233  * indirectly), so synchronous reads can be issued without worrying about
 1234  * the B_INVAL state.  We have to be a little more careful when dealing
 1235  * with writes (see comments in nfs_write()) when extending a file past
 1236  * its EOF.
 1237  */
 1238 static struct buf *
 1239 nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size, struct thread *td)
 1240 {
 1241         struct buf *bp;
 1242         struct mount *mp;
 1243         struct nfsmount *nmp;
 1244 
 1245         mp = vp->v_mount;
 1246         nmp = VFSTONFS(mp);
 1247 
 1248         if (nmp->nm_flag & NFSMNT_INT) {
 1249                 sigset_t oldset;
 1250 
 1251                 nfs_set_sigmask(td, &oldset);
 1252                 bp = getblk(vp, bn, size, PCATCH, 0, 0);
 1253                 nfs_restore_sigmask(td, &oldset);
 1254                 while (bp == NULL) {
 1255                         if (nfs_sigintr(nmp, NULL, td))
 1256                                 return (NULL);
 1257                         bp = getblk(vp, bn, size, 0, 2 * hz, 0);
 1258                 }
 1259         } else {
 1260                 bp = getblk(vp, bn, size, 0, 0, 0);
 1261         }
 1262 
 1263         if (vp->v_type == VREG) {
 1264                 int biosize;
 1265 
 1266                 biosize = mp->mnt_stat.f_iosize;
 1267                 bp->b_blkno = bn * (biosize / DEV_BSIZE);
 1268         }
 1269         return (bp);
 1270 }
 1271 
 1272 /*
 1273  * Flush and invalidate all dirty buffers. If another process is already
 1274  * doing the flush, just wait for completion.
 1275  */
 1276 int
 1277 nfs_vinvalbuf(struct vnode *vp, int flags, struct thread *td, int intrflg)
 1278 {
 1279         struct nfsnode *np = VTONFS(vp);
 1280         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
 1281         int error = 0, slpflag, slptimeo;
 1282         int old_lock = 0;
 1283 
 1284         ASSERT_VOP_LOCKED(vp, "nfs_vinvalbuf");
 1285 
 1286         /*
 1287          * XXX This check stops us from needlessly doing a vinvalbuf when
 1288          * being called through vclean().  It is not clear that this is
 1289          * unsafe.
 1290          */
 1291         if (vp->v_iflag & VI_DOOMED)
 1292                 return (0);
 1293 
 1294         if ((nmp->nm_flag & NFSMNT_INT) == 0)
 1295                 intrflg = 0;
 1296         if (intrflg) {
 1297                 slpflag = PCATCH;
 1298                 slptimeo = 2 * hz;
 1299         } else {
 1300                 slpflag = 0;
 1301                 slptimeo = 0;
 1302         }
 1303 
 1304         if ((old_lock = VOP_ISLOCKED(vp, td)) != LK_EXCLUSIVE) {
 1305                 if (old_lock == LK_SHARED) {
 1306                         /* Upgrade to exclusive lock, this might block */
 1307                         vn_lock(vp, LK_UPGRADE | LK_RETRY, td);
 1308                 } else {
 1309                         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
 1310                 }
 1311         }
 1312 
 1313         /*
 1314          * Now, flush as required.
 1315          */
 1316         if ((flags & V_SAVE) && (vp->v_bufobj.bo_object != NULL)) {
 1317                 VM_OBJECT_LOCK(vp->v_bufobj.bo_object);
 1318                 vm_object_page_clean(vp->v_bufobj.bo_object, 0, 0, OBJPC_SYNC);
 1319                 VM_OBJECT_UNLOCK(vp->v_bufobj.bo_object);
 1320                 /*
 1321                  * If the page clean was interrupted, fail the invalidation.
 1322                  * Not doing so, we run the risk of losing dirty pages in the 
 1323                  * vinvalbuf() call below.
 1324                  */
 1325                 if (intrflg && (error = nfs_sigintr(nmp, NULL, td)))
 1326                         goto out;
 1327         }
 1328 
 1329         error = vinvalbuf(vp, flags, td, slpflag, 0);
 1330         while (error) {
 1331                 if (intrflg && (error = nfs_sigintr(nmp, NULL, td)))
 1332                         goto out;
 1333                 error = vinvalbuf(vp, flags, td, 0, slptimeo);
 1334         }
 1335         if (np->n_directio_asyncwr == 0)
 1336                 np->n_flag &= ~NMODIFIED;
 1337 out:
 1338         if (old_lock != LK_EXCLUSIVE) {
 1339                 if (old_lock == LK_SHARED) {
 1340                         /* Downgrade from exclusive lock, this might block */
 1341                         vn_lock(vp, LK_DOWNGRADE, td);
 1342                 } else {
 1343                         VOP_UNLOCK(vp, 0, td);
 1344                 }
 1345         }
 1346         return error;
 1347 }
 1348 
 1349 /*
 1350  * Initiate asynchronous I/O. Return an error if no nfsiods are available.
 1351  * This is mainly to avoid queueing async I/O requests when the nfsiods
 1352  * are all hung on a dead server.
 1353  *
 1354  * Note: nfs_asyncio() does not clear (BIO_ERROR|B_INVAL) but when the bp
 1355  * is eventually dequeued by the async daemon, nfs_doio() *will*.
 1356  */
 1357 int
 1358 nfs_asyncio(struct nfsmount *nmp, struct buf *bp, struct ucred *cred, struct thread *td)
 1359 {
 1360         int iod;
 1361         int gotiod;
 1362         int slpflag = 0;
 1363         int slptimeo = 0;
 1364         int error, error2;
 1365 
 1366         /*
 1367          * Commits are usually short and sweet so lets save some cpu and
 1368          * leave the async daemons for more important rpc's (such as reads
 1369          * and writes).
 1370          */
 1371         if (bp->b_iocmd == BIO_WRITE && (bp->b_flags & B_NEEDCOMMIT) &&
 1372             (nmp->nm_bufqiods > nfs_numasync / 2)) {
 1373                 return(EIO);
 1374         }
 1375 
 1376 again:
 1377         if (nmp->nm_flag & NFSMNT_INT)
 1378                 slpflag = PCATCH;
 1379         gotiod = FALSE;
 1380 
 1381         /*
 1382          * Find a free iod to process this request.
 1383          */
 1384         for (iod = 0; iod < nfs_numasync; iod++)
 1385                 if (nfs_iodwant[iod]) {
 1386                         gotiod = TRUE;
 1387                         break;
 1388                 }
 1389 
 1390         /*
 1391          * Try to create one if none are free.
 1392          */
 1393         if (!gotiod) {
 1394                 iod = nfs_nfsiodnew();
 1395                 if (iod != -1)
 1396                         gotiod = TRUE;
 1397         }
 1398 
 1399         if (gotiod) {
 1400                 /*
 1401                  * Found one, so wake it up and tell it which
 1402                  * mount to process.
 1403                  */
 1404                 NFS_DPF(ASYNCIO, ("nfs_asyncio: waking iod %d for mount %p\n",
 1405                     iod, nmp));
 1406                 nfs_iodwant[iod] = NULL;
 1407                 nfs_iodmount[iod] = nmp;
 1408                 nmp->nm_bufqiods++;
 1409                 wakeup(&nfs_iodwant[iod]);
 1410         }
 1411 
 1412         /*
 1413          * If none are free, we may already have an iod working on this mount
 1414          * point.  If so, it will process our request.
 1415          */
 1416         if (!gotiod) {
 1417                 if (nmp->nm_bufqiods > 0) {
 1418                         NFS_DPF(ASYNCIO,
 1419                                 ("nfs_asyncio: %d iods are already processing mount %p\n",
 1420                                  nmp->nm_bufqiods, nmp));
 1421                         gotiod = TRUE;
 1422                 }
 1423         }
 1424 
 1425         /*
 1426          * If we have an iod which can process the request, then queue
 1427          * the buffer.
 1428          */
 1429         if (gotiod) {
 1430                 /*
 1431                  * Ensure that the queue never grows too large.  We still want
 1432                  * to asynchronize so we block rather then return EIO.
 1433                  */
 1434                 while (nmp->nm_bufqlen >= 2*nfs_numasync) {
 1435                         NFS_DPF(ASYNCIO,
 1436                                 ("nfs_asyncio: waiting for mount %p queue to drain\n", nmp));
 1437                         nmp->nm_bufqwant = TRUE;
 1438                         error = nfs_tsleep(td, &nmp->nm_bufq, slpflag | PRIBIO,
 1439                                            "nfsaio", slptimeo);
 1440                         if (error) {
 1441                                 error2 = nfs_sigintr(nmp, NULL, td);
 1442                                 if (error2)
 1443                                         return (error2);
 1444                                 if (slpflag == PCATCH) {
 1445                                         slpflag = 0;
 1446                                         slptimeo = 2 * hz;
 1447                                 }
 1448                         }
 1449                         /*
 1450                          * We might have lost our iod while sleeping,
 1451                          * so check and loop if nescessary.
 1452                          */
 1453                         if (nmp->nm_bufqiods == 0) {
 1454                                 NFS_DPF(ASYNCIO,
 1455                                         ("nfs_asyncio: no iods after mount %p queue was drained, looping\n", nmp));
 1456                                 goto again;
 1457                         }
 1458                 }
 1459 
 1460                 if (bp->b_iocmd == BIO_READ) {
 1461                         if (bp->b_rcred == NOCRED && cred != NOCRED)
 1462                                 bp->b_rcred = crhold(cred);
 1463                 } else {
 1464                         if (bp->b_wcred == NOCRED && cred != NOCRED)
 1465                                 bp->b_wcred = crhold(cred);
 1466                 }
 1467 
 1468                 if (bp->b_flags & B_REMFREE)
 1469                         bremfreef(bp);
 1470                 BUF_KERNPROC(bp);
 1471                 TAILQ_INSERT_TAIL(&nmp->nm_bufq, bp, b_freelist);
 1472                 nmp->nm_bufqlen++;
 1473                 if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1474                         VTONFS(bp->b_vp)->n_flag |= NMODIFIED;
 1475                         VTONFS(bp->b_vp)->n_directio_asyncwr++;
 1476                 }
 1477                 return (0);
 1478         }
 1479 
 1480         /*
 1481          * All the iods are busy on other mounts, so return EIO to
 1482          * force the caller to process the i/o synchronously.
 1483          */
 1484         NFS_DPF(ASYNCIO, ("nfs_asyncio: no iods available, i/o is synchronous\n"));
 1485         return (EIO);
 1486 }
 1487 
 1488 void
 1489 nfs_doio_directwrite(struct buf *bp)
 1490 {
 1491         int iomode, must_commit;
 1492         struct uio *uiop = (struct uio *)bp->b_caller1;
 1493         char *iov_base = uiop->uio_iov->iov_base;
 1494         struct nfsmount *nmp = VFSTONFS(bp->b_vp->v_mount);
 1495         
 1496         iomode = NFSV3WRITE_FILESYNC;
 1497         uiop->uio_td = NULL; /* NULL since we're in nfsiod */
 1498         (nmp->nm_rpcops->nr_writerpc)(bp->b_vp, uiop, bp->b_wcred, &iomode, &must_commit);
 1499         KASSERT((must_commit == 0), ("nfs_doio_directwrite: Did not commit write"));
 1500         free(iov_base, M_NFSDIRECTIO);
 1501         free(uiop->uio_iov, M_NFSDIRECTIO);
 1502         free(uiop, M_NFSDIRECTIO);
 1503         if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1504                 struct nfsnode *np = VTONFS(bp->b_vp);
 1505                 
 1506                 np->n_directio_asyncwr--;
 1507                 if (np->n_directio_asyncwr == 0) {
 1508                         VTONFS(bp->b_vp)->n_flag &= ~NMODIFIED;
 1509                         if ((np->n_flag & NFSYNCWAIT)) {
 1510                                 np->n_flag &= ~NFSYNCWAIT;
 1511                                 wakeup((caddr_t)&np->n_directio_asyncwr);
 1512                         }
 1513                 }
 1514         }
 1515         bp->b_vp = NULL;
 1516         relpbuf(bp, &nfs_pbuf_freecnt);
 1517 }
 1518 
 1519 /*
 1520  * Do an I/O operation to/from a cache block. This may be called
 1521  * synchronously or from an nfsiod.
 1522  */
 1523 int
 1524 nfs_doio(struct vnode *vp, struct buf *bp, struct ucred *cr, struct thread *td)
 1525 {
 1526         struct uio *uiop;
 1527         struct nfsnode *np;
 1528         struct nfsmount *nmp;
 1529         int error = 0, iomode, must_commit = 0;
 1530         struct uio uio;
 1531         struct iovec io;
 1532         struct proc *p = td ? td->td_proc : NULL;
 1533 
 1534         np = VTONFS(vp);
 1535         nmp = VFSTONFS(vp->v_mount);
 1536         uiop = &uio;
 1537         uiop->uio_iov = &io;
 1538         uiop->uio_iovcnt = 1;
 1539         uiop->uio_segflg = UIO_SYSSPACE;
 1540         uiop->uio_td = td;
 1541 
 1542         /*
 1543          * clear BIO_ERROR and B_INVAL state prior to initiating the I/O.  We
 1544          * do this here so we do not have to do it in all the code that
 1545          * calls us.
 1546          */
 1547         bp->b_flags &= ~B_INVAL;
 1548         bp->b_ioflags &= ~BIO_ERROR;
 1549 
 1550         KASSERT(!(bp->b_flags & B_DONE), ("nfs_doio: bp %p already marked done", bp));
 1551 
 1552         if (bp->b_iocmd == BIO_READ) {
 1553             io.iov_len = uiop->uio_resid = bp->b_bcount;
 1554             io.iov_base = bp->b_data;
 1555             uiop->uio_rw = UIO_READ;
 1556 
 1557             switch (vp->v_type) {
 1558             case VREG:
 1559                 uiop->uio_offset = ((off_t)bp->b_blkno) * DEV_BSIZE;
 1560                 nfsstats.read_bios++;
 1561                 error = (nmp->nm_rpcops->nr_readrpc)(vp, uiop, cr);
 1562 
 1563                 if (!error) {
 1564                     if (uiop->uio_resid) {
 1565                         /*
 1566                          * If we had a short read with no error, we must have
 1567                          * hit a file hole.  We should zero-fill the remainder.
 1568                          * This can also occur if the server hits the file EOF.
 1569                          *
 1570                          * Holes used to be able to occur due to pending
 1571                          * writes, but that is not possible any longer.
 1572                          */
 1573                         int nread = bp->b_bcount - uiop->uio_resid;
 1574                         int left  = uiop->uio_resid;
 1575 
 1576                         if (left > 0)
 1577                                 bzero((char *)bp->b_data + nread, left);
 1578                         uiop->uio_resid = 0;
 1579                     }
 1580                 }
 1581                 /* ASSERT_VOP_LOCKED(vp, "nfs_doio"); */
 1582                 if (p && (vp->v_vflag & VV_TEXT) &&
 1583                     (NFS_TIMESPEC_COMPARE(&np->n_mtime, &np->n_vattr.va_mtime))) {
 1584                         PROC_LOCK(p);
 1585                         killproc(p, "text file modification");
 1586                         PROC_UNLOCK(p);
 1587                 }
 1588                 break;
 1589             case VLNK:
 1590                 uiop->uio_offset = (off_t)0;
 1591                 nfsstats.readlink_bios++;
 1592                 error = (nmp->nm_rpcops->nr_readlinkrpc)(vp, uiop, cr);
 1593                 break;
 1594             case VDIR:
 1595                 nfsstats.readdir_bios++;
 1596                 uiop->uio_offset = ((u_quad_t)bp->b_lblkno) * NFS_DIRBLKSIZ;
 1597                 if ((nmp->nm_flag & NFSMNT_NFSV4) != 0)
 1598                         error = nfs4_readdirrpc(vp, uiop, cr);
 1599                 else {
 1600                         if ((nmp->nm_flag & NFSMNT_RDIRPLUS) != 0) {
 1601                                 error = nfs_readdirplusrpc(vp, uiop, cr);
 1602                                 if (error == NFSERR_NOTSUPP)
 1603                                         nmp->nm_flag &= ~NFSMNT_RDIRPLUS;
 1604                         }
 1605                         if ((nmp->nm_flag & NFSMNT_RDIRPLUS) == 0)
 1606                                 error = nfs_readdirrpc(vp, uiop, cr);
 1607                 }
 1608                 /*
 1609                  * end-of-directory sets B_INVAL but does not generate an
 1610                  * error.
 1611                  */
 1612                 if (error == 0 && uiop->uio_resid == bp->b_bcount)
 1613                         bp->b_flags |= B_INVAL;
 1614                 break;
 1615             default:
 1616                 printf("nfs_doio:  type %x unexpected\n", vp->v_type);
 1617                 break;
 1618             };
 1619             if (error) {
 1620                 bp->b_ioflags |= BIO_ERROR;
 1621                 bp->b_error = error;
 1622             }
 1623         } else {
 1624             /*
 1625              * If we only need to commit, try to commit
 1626              */
 1627             if (bp->b_flags & B_NEEDCOMMIT) {
 1628                     int retv;
 1629                     off_t off;
 1630 
 1631                     off = ((u_quad_t)bp->b_blkno) * DEV_BSIZE + bp->b_dirtyoff;
 1632                     retv = (nmp->nm_rpcops->nr_commit)(
 1633                                 vp, off, bp->b_dirtyend-bp->b_dirtyoff,
 1634                                 bp->b_wcred, td);
 1635                     if (retv == 0) {
 1636                             bp->b_dirtyoff = bp->b_dirtyend = 0;
 1637                             bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1638                             bp->b_resid = 0;
 1639                             bufdone(bp);
 1640                             return (0);
 1641                     }
 1642                     if (retv == NFSERR_STALEWRITEVERF) {
 1643                             nfs_clearcommit(vp->v_mount);
 1644                     }
 1645             }
 1646 
 1647             /*
 1648              * Setup for actual write
 1649              */
 1650 
 1651             if ((off_t)bp->b_blkno * DEV_BSIZE + bp->b_dirtyend > np->n_size)
 1652                 bp->b_dirtyend = np->n_size - (off_t)bp->b_blkno * DEV_BSIZE;
 1653 
 1654             if (bp->b_dirtyend > bp->b_dirtyoff) {
 1655                 io.iov_len = uiop->uio_resid = bp->b_dirtyend
 1656                     - bp->b_dirtyoff;
 1657                 uiop->uio_offset = (off_t)bp->b_blkno * DEV_BSIZE
 1658                     + bp->b_dirtyoff;
 1659                 io.iov_base = (char *)bp->b_data + bp->b_dirtyoff;
 1660                 uiop->uio_rw = UIO_WRITE;
 1661                 nfsstats.write_bios++;
 1662 
 1663                 if ((bp->b_flags & (B_ASYNC | B_NEEDCOMMIT | B_NOCACHE | B_CLUSTER)) == B_ASYNC)
 1664                     iomode = NFSV3WRITE_UNSTABLE;
 1665                 else
 1666                     iomode = NFSV3WRITE_FILESYNC;
 1667 
 1668                 error = (nmp->nm_rpcops->nr_writerpc)(vp, uiop, cr, &iomode, &must_commit);
 1669 
 1670                 /*
 1671                  * When setting B_NEEDCOMMIT also set B_CLUSTEROK to try
 1672                  * to cluster the buffers needing commit.  This will allow
 1673                  * the system to submit a single commit rpc for the whole
 1674                  * cluster.  We can do this even if the buffer is not 100%
 1675                  * dirty (relative to the NFS blocksize), so we optimize the
 1676                  * append-to-file-case.
 1677                  *
 1678                  * (when clearing B_NEEDCOMMIT, B_CLUSTEROK must also be
 1679                  * cleared because write clustering only works for commit
 1680                  * rpc's, not for the data portion of the write).
 1681                  */
 1682 
 1683                 if (!error && iomode == NFSV3WRITE_UNSTABLE) {
 1684                     bp->b_flags |= B_NEEDCOMMIT;
 1685                     if (bp->b_dirtyoff == 0
 1686                         && bp->b_dirtyend == bp->b_bcount)
 1687                         bp->b_flags |= B_CLUSTEROK;
 1688                 } else {
 1689                     bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1690                 }
 1691 
 1692                 /*
 1693                  * For an interrupted write, the buffer is still valid
 1694                  * and the write hasn't been pushed to the server yet,
 1695                  * so we can't set BIO_ERROR and report the interruption
 1696                  * by setting B_EINTR. For the B_ASYNC case, B_EINTR
 1697                  * is not relevant, so the rpc attempt is essentially
 1698                  * a noop.  For the case of a V3 write rpc not being
 1699                  * committed to stable storage, the block is still
 1700                  * dirty and requires either a commit rpc or another
 1701                  * write rpc with iomode == NFSV3WRITE_FILESYNC before
 1702                  * the block is reused. This is indicated by setting
 1703                  * the B_DELWRI and B_NEEDCOMMIT flags.
 1704                  *
 1705                  * If the buffer is marked B_PAGING, it does not reside on
 1706                  * the vp's paging queues so we cannot call bdirty().  The
 1707                  * bp in this case is not an NFS cache block so we should
 1708                  * be safe. XXX
 1709                  *
 1710                  * The logic below breaks up errors into recoverable and 
 1711                  * unrecoverable. For the former, we clear B_INVAL|B_NOCACHE
 1712                  * and keep the buffer around for potential write retries.
 1713                  * For the latter (eg ESTALE), we toss the buffer away (B_INVAL)
 1714                  * and save the error in the nfsnode. This is less than ideal 
 1715                  * but necessary. Keeping such buffers around could potentially
 1716                  * cause buffer exhaustion eventually (they can never be written
 1717                  * out, so will get constantly be re-dirtied). It also causes
 1718                  * all sorts of vfs panics. For non-recoverable write errors, 
 1719                  * also invalidate the attrcache, so we'll be forced to go over
 1720                  * the wire for this object, returning an error to user on next
 1721                  * call (most of the time).
 1722                  */
 1723                 if (error == EINTR || error == EIO || error == ETIMEDOUT
 1724                     || (!error && (bp->b_flags & B_NEEDCOMMIT))) {
 1725                         int s;
 1726 
 1727                         s = splbio();
 1728                         bp->b_flags &= ~(B_INVAL|B_NOCACHE);
 1729                         if ((bp->b_flags & B_PAGING) == 0) {
 1730                             bdirty(bp);
 1731                             bp->b_flags &= ~B_DONE;
 1732                         }
 1733                         if (error && (bp->b_flags & B_ASYNC) == 0)
 1734                             bp->b_flags |= B_EINTR;
 1735                         splx(s);
 1736                 } else {
 1737                     if (error) {
 1738                         bp->b_ioflags |= BIO_ERROR;
 1739                         bp->b_flags |= B_INVAL;
 1740                         bp->b_error = np->n_error = error;
 1741                         np->n_flag |= NWRITEERR;
 1742                         np->n_attrstamp = 0;
 1743                     }
 1744                     bp->b_dirtyoff = bp->b_dirtyend = 0;
 1745                 }
 1746             } else {
 1747                 bp->b_resid = 0;
 1748                 bufdone(bp);
 1749                 return (0);
 1750             }
 1751         }
 1752         bp->b_resid = uiop->uio_resid;
 1753         if (must_commit)
 1754             nfs_clearcommit(vp->v_mount);
 1755         bufdone(bp);
 1756         return (error);
 1757 }
 1758 
 1759 /*
 1760  * Used to aid in handling ftruncate() operations on the NFS client side.
 1761  * Truncation creates a number of special problems for NFS.  We have to
 1762  * throw away VM pages and buffer cache buffers that are beyond EOF, and
 1763  * we have to properly handle VM pages or (potentially dirty) buffers
 1764  * that straddle the truncation point.
 1765  */
 1766 
 1767 int
 1768 nfs_meta_setsize(struct vnode *vp, struct ucred *cred, struct thread *td, u_quad_t nsize)
 1769 {
 1770         struct nfsnode *np = VTONFS(vp);
 1771         u_quad_t tsize = np->n_size;
 1772         int biosize = vp->v_mount->mnt_stat.f_iosize;
 1773         int error = 0;
 1774 
 1775         np->n_size = nsize;
 1776 
 1777         if (np->n_size < tsize) {
 1778                 struct buf *bp;
 1779                 daddr_t lbn;
 1780                 int bufsize;
 1781 
 1782                 /*
 1783                  * vtruncbuf() doesn't get the buffer overlapping the 
 1784                  * truncation point.  We may have a B_DELWRI and/or B_CACHE
 1785                  * buffer that now needs to be truncated.
 1786                  */
 1787                 error = vtruncbuf(vp, cred, td, nsize, biosize);
 1788                 lbn = nsize / biosize;
 1789                 bufsize = nsize & (biosize - 1);
 1790                 bp = nfs_getcacheblk(vp, lbn, bufsize, td);
 1791                 if (!bp)
 1792                         return EINTR;
 1793                 if (bp->b_dirtyoff > bp->b_bcount)
 1794                         bp->b_dirtyoff = bp->b_bcount;
 1795                 if (bp->b_dirtyend > bp->b_bcount)
 1796                         bp->b_dirtyend = bp->b_bcount;
 1797                 bp->b_flags |= B_RELBUF;  /* don't leave garbage around */
 1798                 brelse(bp);
 1799         } else {
 1800                 vnode_pager_setsize(vp, nsize);
 1801         }
 1802         return(error);
 1803 }
 1804 

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