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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: stable/7/sys/nfsclient/nfs_bio.c 214986 2010-11-08 15:22:20Z kib $");
   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 /*
   76  * Vnode op for VM getpages.
   77  */
   78 int
   79 nfs_getpages(struct vop_getpages_args *ap)
   80 {
   81         int i, error, nextoff, size, toff, count, npages;
   82         struct uio uio;
   83         struct iovec iov;
   84         vm_offset_t kva;
   85         struct buf *bp;
   86         struct vnode *vp;
   87         struct thread *td;
   88         struct ucred *cred;
   89         struct nfsmount *nmp;
   90         vm_object_t object;
   91         vm_page_t *pages;
   92         struct nfsnode *np;
   93 
   94         vp = ap->a_vp;
   95         np = VTONFS(vp);
   96         td = curthread;                         /* XXX */
   97         cred = curthread->td_ucred;             /* XXX */
   98         nmp = VFSTONFS(vp->v_mount);
   99         pages = ap->a_m;
  100         count = ap->a_count;
  101 
  102         if ((object = vp->v_object) == NULL) {
  103                 nfs_printf("nfs_getpages: called with non-merged cache vnode??\n");
  104                 return VM_PAGER_ERROR;
  105         }
  106 
  107         if (nfs_directio_enable && !nfs_directio_allow_mmap) {
  108                 mtx_lock(&np->n_mtx);
  109                 if ((np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
  110                         mtx_unlock(&np->n_mtx);
  111                         nfs_printf("nfs_getpages: called on non-cacheable vnode??\n");
  112                         return VM_PAGER_ERROR;
  113                 } else
  114                         mtx_unlock(&np->n_mtx);
  115         }
  116 
  117         mtx_lock(&nmp->nm_mtx);
  118         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  119             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {  
  120                 mtx_unlock(&nmp->nm_mtx);
  121                 /* We'll never get here for v4, because we always have fsinfo */
  122                 (void)nfs_fsinfo(nmp, vp, cred, td);
  123         } else
  124                 mtx_unlock(&nmp->nm_mtx);
  125 
  126         npages = btoc(count);
  127 
  128         /*
  129          * If the requested page is partially valid, just return it and
  130          * allow the pager to zero-out the blanks.  Partially valid pages
  131          * can only occur at the file EOF.
  132          */
  133 
  134         {
  135                 vm_page_t m = pages[ap->a_reqpage];
  136 
  137                 VM_OBJECT_LOCK(object);
  138                 vm_page_lock_queues();
  139                 if (m->valid != 0) {
  140                         /* handled by vm_fault now        */
  141                         /* vm_page_zero_invalid(m, TRUE); */
  142                         for (i = 0; i < npages; ++i) {
  143                                 if (i != ap->a_reqpage)
  144                                         vm_page_free(pages[i]);
  145                         }
  146                         vm_page_unlock_queues();
  147                         VM_OBJECT_UNLOCK(object);
  148                         return(0);
  149                 }
  150                 vm_page_unlock_queues();
  151                 VM_OBJECT_UNLOCK(object);
  152         }
  153 
  154         /*
  155          * We use only the kva address for the buffer, but this is extremely
  156          * convienient and fast.
  157          */
  158         bp = getpbuf(&nfs_pbuf_freecnt);
  159 
  160         kva = (vm_offset_t) bp->b_data;
  161         pmap_qenter(kva, pages, npages);
  162         PCPU_INC(cnt.v_vnodein);
  163         PCPU_ADD(cnt.v_vnodepgsin, npages);
  164 
  165         iov.iov_base = (caddr_t) kva;
  166         iov.iov_len = count;
  167         uio.uio_iov = &iov;
  168         uio.uio_iovcnt = 1;
  169         uio.uio_offset = IDX_TO_OFF(pages[0]->pindex);
  170         uio.uio_resid = count;
  171         uio.uio_segflg = UIO_SYSSPACE;
  172         uio.uio_rw = UIO_READ;
  173         uio.uio_td = td;
  174 
  175         error = (nmp->nm_rpcops->nr_readrpc)(vp, &uio, cred);
  176         pmap_qremove(kva, npages);
  177 
  178         relpbuf(bp, &nfs_pbuf_freecnt);
  179 
  180         if (error && (uio.uio_resid == count)) {
  181                 nfs_printf("nfs_getpages: error %d\n", error);
  182                 VM_OBJECT_LOCK(object);
  183                 vm_page_lock_queues();
  184                 for (i = 0; i < npages; ++i) {
  185                         if (i != ap->a_reqpage)
  186                                 vm_page_free(pages[i]);
  187                 }
  188                 vm_page_unlock_queues();
  189                 VM_OBJECT_UNLOCK(object);
  190                 return VM_PAGER_ERROR;
  191         }
  192 
  193         /*
  194          * Calculate the number of bytes read and validate only that number
  195          * of bytes.  Note that due to pending writes, size may be 0.  This
  196          * does not mean that the remaining data is invalid!
  197          */
  198 
  199         size = count - uio.uio_resid;
  200         VM_OBJECT_LOCK(object);
  201         vm_page_lock_queues();
  202         for (i = 0, toff = 0; i < npages; i++, toff = nextoff) {
  203                 vm_page_t m;
  204                 nextoff = toff + PAGE_SIZE;
  205                 m = pages[i];
  206 
  207                 if (nextoff <= size) {
  208                         /*
  209                          * Read operation filled an entire page
  210                          */
  211                         m->valid = VM_PAGE_BITS_ALL;
  212                         vm_page_undirty(m);
  213                 } else if (size > toff) {
  214                         /*
  215                          * Read operation filled a partial page.
  216                          */
  217                         m->valid = 0;
  218                         vm_page_set_validclean(m, 0, size - toff);
  219                         /* handled by vm_fault now        */
  220                         /* vm_page_zero_invalid(m, TRUE); */
  221                 } else {
  222                         /*
  223                          * Read operation was short.  If no error occured
  224                          * we may have hit a zero-fill section.   We simply
  225                          * leave valid set to 0.
  226                          */
  227                         ;
  228                 }
  229                 if (i != ap->a_reqpage) {
  230                         /*
  231                          * Whether or not to leave the page activated is up in
  232                          * the air, but we should put the page on a page queue
  233                          * somewhere (it already is in the object).  Result:
  234                          * It appears that emperical results show that
  235                          * deactivating pages is best.
  236                          */
  237 
  238                         /*
  239                          * Just in case someone was asking for this page we
  240                          * now tell them that it is ok to use.
  241                          */
  242                         if (!error) {
  243                                 if (m->oflags & VPO_WANTED)
  244                                         vm_page_activate(m);
  245                                 else
  246                                         vm_page_deactivate(m);
  247                                 vm_page_wakeup(m);
  248                         } else {
  249                                 vm_page_free(m);
  250                         }
  251                 }
  252         }
  253         vm_page_unlock_queues();
  254         VM_OBJECT_UNLOCK(object);
  255         return 0;
  256 }
  257 
  258 /*
  259  * Vnode op for VM putpages.
  260  */
  261 int
  262 nfs_putpages(struct vop_putpages_args *ap)
  263 {
  264         struct uio uio;
  265         struct iovec iov;
  266         vm_offset_t kva;
  267         struct buf *bp;
  268         int iomode, must_commit, i, error, npages, count;
  269         off_t offset;
  270         int *rtvals;
  271         struct vnode *vp;
  272         struct thread *td;
  273         struct ucred *cred;
  274         struct nfsmount *nmp;
  275         struct nfsnode *np;
  276         vm_page_t *pages;
  277 
  278         vp = ap->a_vp;
  279         np = VTONFS(vp);
  280         td = curthread;                         /* XXX */
  281         cred = curthread->td_ucred;             /* XXX */
  282         nmp = VFSTONFS(vp->v_mount);
  283         pages = ap->a_m;
  284         count = ap->a_count;
  285         rtvals = ap->a_rtvals;
  286         npages = btoc(count);
  287         offset = IDX_TO_OFF(pages[0]->pindex);
  288         
  289         mtx_lock(&nmp->nm_mtx);
  290         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  291             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  292                 mtx_unlock(&nmp->nm_mtx);
  293                 (void)nfs_fsinfo(nmp, vp, cred, td);
  294         } else
  295                 mtx_unlock(&nmp->nm_mtx);
  296 
  297         mtx_lock(&np->n_mtx);
  298         if (nfs_directio_enable && !nfs_directio_allow_mmap && 
  299             (np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
  300                 mtx_unlock(&np->n_mtx);         
  301                 nfs_printf("nfs_putpages: called on noncache-able vnode??\n");
  302                 mtx_lock(&np->n_mtx);
  303         }
  304 
  305         for (i = 0; i < npages; i++)
  306                 rtvals[i] = VM_PAGER_AGAIN;
  307 
  308         /*
  309          * When putting pages, do not extend file past EOF.
  310          */
  311         if (offset + count > np->n_size) {
  312                 count = np->n_size - offset;
  313                 if (count < 0)
  314                         count = 0;
  315         }
  316         mtx_unlock(&np->n_mtx);
  317 
  318         /*
  319          * We use only the kva address for the buffer, but this is extremely
  320          * convienient and fast.
  321          */
  322         bp = getpbuf(&nfs_pbuf_freecnt);
  323 
  324         kva = (vm_offset_t) bp->b_data;
  325         pmap_qenter(kva, pages, npages);
  326         PCPU_INC(cnt.v_vnodeout);
  327         PCPU_ADD(cnt.v_vnodepgsout, count);
  328 
  329         iov.iov_base = (caddr_t) kva;
  330         iov.iov_len = count;
  331         uio.uio_iov = &iov;
  332         uio.uio_iovcnt = 1;
  333         uio.uio_offset = offset;
  334         uio.uio_resid = count;
  335         uio.uio_segflg = UIO_SYSSPACE;
  336         uio.uio_rw = UIO_WRITE;
  337         uio.uio_td = td;
  338 
  339         if ((ap->a_sync & VM_PAGER_PUT_SYNC) == 0)
  340             iomode = NFSV3WRITE_UNSTABLE;
  341         else
  342             iomode = NFSV3WRITE_FILESYNC;
  343 
  344         error = (nmp->nm_rpcops->nr_writerpc)(vp, &uio, cred, &iomode, &must_commit);
  345 
  346         pmap_qremove(kva, npages);
  347         relpbuf(bp, &nfs_pbuf_freecnt);
  348 
  349         if (!error) {
  350                 int nwritten = round_page(count - uio.uio_resid) / PAGE_SIZE;
  351                 for (i = 0; i < nwritten; i++) {
  352                         rtvals[i] = VM_PAGER_OK;
  353                         vm_page_undirty(pages[i]);
  354                 }
  355                 if (must_commit) {
  356                         nfs_clearcommit(vp->v_mount);
  357                 }
  358         }
  359         return rtvals[0];
  360 }
  361 
  362 /*
  363  * For nfs, cache consistency can only be maintained approximately.
  364  * Although RFC1094 does not specify the criteria, the following is
  365  * believed to be compatible with the reference port.
  366  * For nfs:
  367  * If the file's modify time on the server has changed since the
  368  * last read rpc or you have written to the file,
  369  * you may have lost data cache consistency with the
  370  * server, so flush all of the file's data out of the cache.
  371  * Then force a getattr rpc to ensure that you have up to date
  372  * attributes.
  373  * NB: This implies that cache data can be read when up to
  374  * NFS_ATTRTIMEO seconds out of date. If you find that you need current
  375  * attributes this could be forced by setting n_attrstamp to 0 before
  376  * the VOP_GETATTR() call.
  377  */
  378 static inline int
  379 nfs_bioread_check_cons(struct vnode *vp, struct thread *td, struct ucred *cred)
  380 {
  381         int error = 0;
  382         struct vattr vattr;
  383         struct nfsnode *np = VTONFS(vp);
  384         int old_lock;
  385         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  386         
  387         /*
  388          * Grab the exclusive lock before checking whether the cache is
  389          * consistent.
  390          * XXX - We can make this cheaper later (by acquiring cheaper locks).
  391          * But for now, this suffices.
  392          */
  393         old_lock = nfs_upgrade_vnlock(vp, td);
  394         mtx_lock(&np->n_mtx);
  395         if (np->n_flag & NMODIFIED) {
  396                 mtx_unlock(&np->n_mtx);
  397                 if (vp->v_type != VREG) {
  398                         if (vp->v_type != VDIR)
  399                                 panic("nfs: bioread, not dir");
  400                         (nmp->nm_rpcops->nr_invaldir)(vp);
  401                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  402                         if (error)
  403                                 goto out;
  404                 }
  405                 np->n_attrstamp = 0;
  406                 error = VOP_GETATTR(vp, &vattr, cred, td);
  407                 if (error)
  408                         goto out;
  409                 mtx_lock(&np->n_mtx);
  410                 np->n_mtime = vattr.va_mtime;
  411                 mtx_unlock(&np->n_mtx);
  412         } else {
  413                 mtx_unlock(&np->n_mtx);
  414                 error = VOP_GETATTR(vp, &vattr, cred, td);
  415                 if (error)
  416                         return (error);
  417                 mtx_lock(&np->n_mtx);
  418                 if ((np->n_flag & NSIZECHANGED)
  419                     || (NFS_TIMESPEC_COMPARE(&np->n_mtime, &vattr.va_mtime))) {
  420                         mtx_unlock(&np->n_mtx);
  421                         if (vp->v_type == VDIR)
  422                                 (nmp->nm_rpcops->nr_invaldir)(vp);
  423                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  424                         if (error)
  425                                 goto out;
  426                         mtx_lock(&np->n_mtx);
  427                         np->n_mtime = vattr.va_mtime;
  428                         np->n_flag &= ~NSIZECHANGED;
  429                 }
  430                 mtx_unlock(&np->n_mtx);
  431         }
  432 out:    
  433         nfs_downgrade_vnlock(vp, td, old_lock);
  434         return error;
  435 }
  436 
  437 /*
  438  * Vnode op for read using bio
  439  */
  440 int
  441 nfs_bioread(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred)
  442 {
  443         struct nfsnode *np = VTONFS(vp);
  444         int biosize, i;
  445         struct buf *bp, *rabp;
  446         struct thread *td;
  447         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  448         daddr_t lbn, rabn;
  449         int bcount;
  450         int seqcount;
  451         int nra, error = 0, n = 0, on = 0;
  452 
  453 #ifdef DIAGNOSTIC
  454         if (uio->uio_rw != UIO_READ)
  455                 panic("nfs_read mode");
  456 #endif
  457         if (uio->uio_resid == 0)
  458                 return (0);
  459         if (uio->uio_offset < 0)        /* XXX VDIR cookies can be negative */
  460                 return (EINVAL);
  461         td = uio->uio_td;
  462 
  463         mtx_lock(&nmp->nm_mtx);
  464         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  465             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  466                 mtx_unlock(&nmp->nm_mtx);
  467                 (void)nfs_fsinfo(nmp, vp, cred, td);
  468         } else
  469                 mtx_unlock(&nmp->nm_mtx);               
  470 
  471         if (vp->v_type != VDIR &&
  472             (uio->uio_offset + uio->uio_resid) > nmp->nm_maxfilesize)
  473                 return (EFBIG);
  474 
  475         if (nfs_directio_enable && (ioflag & IO_DIRECT) && (vp->v_type == VREG))
  476                 /* No caching/ no readaheads. Just read data into the user buffer */
  477                 return nfs_readrpc(vp, uio, cred);
  478 
  479         biosize = vp->v_mount->mnt_stat.f_iosize;
  480         seqcount = (int)((off_t)(ioflag >> IO_SEQSHIFT) * biosize / BKVASIZE);
  481         
  482         error = nfs_bioread_check_cons(vp, td, cred);
  483         if (error)
  484                 return error;
  485 
  486         do {
  487             u_quad_t nsize;
  488                         
  489             mtx_lock(&np->n_mtx);
  490             nsize = np->n_size;
  491             mtx_unlock(&np->n_mtx);                 
  492 
  493             switch (vp->v_type) {
  494             case VREG:
  495                 nfsstats.biocache_reads++;
  496                 lbn = uio->uio_offset / biosize;
  497                 on = uio->uio_offset & (biosize - 1);
  498 
  499                 /*
  500                  * Start the read ahead(s), as required.
  501                  */
  502                 if (nmp->nm_readahead > 0) {
  503                     for (nra = 0; nra < nmp->nm_readahead && nra < seqcount &&
  504                         (off_t)(lbn + 1 + nra) * biosize < nsize; nra++) {
  505                         rabn = lbn + 1 + nra;
  506                         if (incore(&vp->v_bufobj, rabn) == NULL) {
  507                             rabp = nfs_getcacheblk(vp, rabn, biosize, td);
  508                             if (!rabp) {
  509                                 error = nfs_sigintr(nmp, NULL, td);
  510                                 return (error ? error : EINTR);
  511                             }
  512                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  513                                 rabp->b_flags |= B_ASYNC;
  514                                 rabp->b_iocmd = BIO_READ;
  515                                 vfs_busy_pages(rabp, 0);
  516                                 if (nfs_asyncio(nmp, rabp, cred, td)) {
  517                                     rabp->b_flags |= B_INVAL;
  518                                     rabp->b_ioflags |= BIO_ERROR;
  519                                     vfs_unbusy_pages(rabp);
  520                                     brelse(rabp);
  521                                     break;
  522                                 }
  523                             } else {
  524                                 brelse(rabp);
  525                             }
  526                         }
  527                     }
  528                 }
  529 
  530                 /* Note that bcount is *not* DEV_BSIZE aligned. */
  531                 bcount = biosize;
  532                 if ((off_t)lbn * biosize >= nsize) {
  533                         bcount = 0;
  534                 } else if ((off_t)(lbn + 1) * biosize > nsize) {
  535                         bcount = nsize - (off_t)lbn * biosize;
  536                 }
  537                 bp = nfs_getcacheblk(vp, lbn, bcount, td);
  538 
  539                 if (!bp) {
  540                         error = nfs_sigintr(nmp, NULL, td);
  541                         return (error ? error : EINTR);
  542                 }
  543 
  544                 /*
  545                  * If B_CACHE is not set, we must issue the read.  If this
  546                  * fails, we return an error.
  547                  */
  548 
  549                 if ((bp->b_flags & B_CACHE) == 0) {
  550                     bp->b_iocmd = BIO_READ;
  551                     vfs_busy_pages(bp, 0);
  552                     error = nfs_doio(vp, bp, cred, td);
  553                     if (error) {
  554                         brelse(bp);
  555                         return (error);
  556                     }
  557                 }
  558 
  559                 /*
  560                  * on is the offset into the current bp.  Figure out how many
  561                  * bytes we can copy out of the bp.  Note that bcount is
  562                  * NOT DEV_BSIZE aligned.
  563                  *
  564                  * Then figure out how many bytes we can copy into the uio.
  565                  */
  566 
  567                 n = 0;
  568                 if (on < bcount)
  569                         n = min((unsigned)(bcount - on), uio->uio_resid);
  570                 break;
  571             case VLNK:
  572                 nfsstats.biocache_readlinks++;
  573                 bp = nfs_getcacheblk(vp, (daddr_t)0, NFS_MAXPATHLEN, td);
  574                 if (!bp) {
  575                         error = nfs_sigintr(nmp, NULL, td);
  576                         return (error ? error : EINTR);
  577                 }
  578                 if ((bp->b_flags & B_CACHE) == 0) {
  579                     bp->b_iocmd = BIO_READ;
  580                     vfs_busy_pages(bp, 0);
  581                     error = nfs_doio(vp, bp, cred, td);
  582                     if (error) {
  583                         bp->b_ioflags |= BIO_ERROR;
  584                         brelse(bp);
  585                         return (error);
  586                     }
  587                 }
  588                 n = min(uio->uio_resid, NFS_MAXPATHLEN - bp->b_resid);
  589                 on = 0;
  590                 break;
  591             case VDIR:
  592                 nfsstats.biocache_readdirs++;
  593                 if (np->n_direofoffset
  594                     && uio->uio_offset >= np->n_direofoffset) {
  595                     return (0);
  596                 }
  597                 lbn = (uoff_t)uio->uio_offset / NFS_DIRBLKSIZ;
  598                 on = uio->uio_offset & (NFS_DIRBLKSIZ - 1);
  599                 bp = nfs_getcacheblk(vp, lbn, NFS_DIRBLKSIZ, td);
  600                 if (!bp) {
  601                     error = nfs_sigintr(nmp, NULL, td);
  602                     return (error ? error : EINTR);
  603                 }
  604                 if ((bp->b_flags & B_CACHE) == 0) {
  605                     bp->b_iocmd = BIO_READ;
  606                     vfs_busy_pages(bp, 0);
  607                     error = nfs_doio(vp, bp, cred, td);
  608                     if (error) {
  609                             brelse(bp);
  610                     }
  611                     while (error == NFSERR_BAD_COOKIE) {
  612                         (nmp->nm_rpcops->nr_invaldir)(vp);
  613                         error = nfs_vinvalbuf(vp, 0, td, 1);
  614                         /*
  615                          * Yuck! The directory has been modified on the
  616                          * server. The only way to get the block is by
  617                          * reading from the beginning to get all the
  618                          * offset cookies.
  619                          *
  620                          * Leave the last bp intact unless there is an error.
  621                          * Loop back up to the while if the error is another
  622                          * NFSERR_BAD_COOKIE (double yuch!).
  623                          */
  624                         for (i = 0; i <= lbn && !error; i++) {
  625                             if (np->n_direofoffset
  626                                 && (i * NFS_DIRBLKSIZ) >= np->n_direofoffset)
  627                                     return (0);
  628                             bp = nfs_getcacheblk(vp, i, NFS_DIRBLKSIZ, td);
  629                             if (!bp) {
  630                                 error = nfs_sigintr(nmp, NULL, td);
  631                                 return (error ? error : EINTR);
  632                             }
  633                             if ((bp->b_flags & B_CACHE) == 0) {
  634                                     bp->b_iocmd = BIO_READ;
  635                                     vfs_busy_pages(bp, 0);
  636                                     error = nfs_doio(vp, bp, cred, td);
  637                                     /*
  638                                      * no error + B_INVAL == directory EOF,
  639                                      * use the block.
  640                                      */
  641                                     if (error == 0 && (bp->b_flags & B_INVAL))
  642                                             break;
  643                             }
  644                             /*
  645                              * An error will throw away the block and the
  646                              * for loop will break out.  If no error and this
  647                              * is not the block we want, we throw away the
  648                              * block and go for the next one via the for loop.
  649                              */
  650                             if (error || i < lbn)
  651                                     brelse(bp);
  652                         }
  653                     }
  654                     /*
  655                      * The above while is repeated if we hit another cookie
  656                      * error.  If we hit an error and it wasn't a cookie error,
  657                      * we give up.
  658                      */
  659                     if (error)
  660                             return (error);
  661                 }
  662 
  663                 /*
  664                  * If not eof and read aheads are enabled, start one.
  665                  * (You need the current block first, so that you have the
  666                  *  directory offset cookie of the next block.)
  667                  */
  668                 if (nmp->nm_readahead > 0 &&
  669                     (bp->b_flags & B_INVAL) == 0 &&
  670                     (np->n_direofoffset == 0 ||
  671                     (lbn + 1) * NFS_DIRBLKSIZ < np->n_direofoffset) &&
  672                     incore(&vp->v_bufobj, lbn + 1) == NULL) {
  673                         rabp = nfs_getcacheblk(vp, lbn + 1, NFS_DIRBLKSIZ, td);
  674                         if (rabp) {
  675                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  676                                 rabp->b_flags |= B_ASYNC;
  677                                 rabp->b_iocmd = BIO_READ;
  678                                 vfs_busy_pages(rabp, 0);
  679                                 if (nfs_asyncio(nmp, rabp, cred, td)) {
  680                                     rabp->b_flags |= B_INVAL;
  681                                     rabp->b_ioflags |= BIO_ERROR;
  682                                     vfs_unbusy_pages(rabp);
  683                                     brelse(rabp);
  684                                 }
  685                             } else {
  686                                 brelse(rabp);
  687                             }
  688                         }
  689                 }
  690                 /*
  691                  * Unlike VREG files, whos buffer size ( bp->b_bcount ) is
  692                  * chopped for the EOF condition, we cannot tell how large
  693                  * NFS directories are going to be until we hit EOF.  So
  694                  * an NFS directory buffer is *not* chopped to its EOF.  Now,
  695                  * it just so happens that b_resid will effectively chop it
  696                  * to EOF.  *BUT* this information is lost if the buffer goes
  697                  * away and is reconstituted into a B_CACHE state ( due to
  698                  * being VMIO ) later.  So we keep track of the directory eof
  699                  * in np->n_direofoffset and chop it off as an extra step
  700                  * right here.
  701                  */
  702                 n = lmin(uio->uio_resid, NFS_DIRBLKSIZ - bp->b_resid - on);
  703                 if (np->n_direofoffset && n > np->n_direofoffset - uio->uio_offset)
  704                         n = np->n_direofoffset - uio->uio_offset;
  705                 break;
  706             default:
  707                 nfs_printf(" nfs_bioread: type %x unexpected\n", vp->v_type);
  708                 bp = NULL;
  709                 break;
  710             };
  711 
  712             if (n > 0) {
  713                     error = uiomove(bp->b_data + on, (int)n, uio);
  714             }
  715             if (vp->v_type == VLNK)
  716                 n = 0;
  717             if (bp != NULL)
  718                 brelse(bp);
  719         } while (error == 0 && uio->uio_resid > 0 && n > 0);
  720         return (error);
  721 }
  722 
  723 /*
  724  * The NFS write path cannot handle iovecs with len > 1. So we need to 
  725  * break up iovecs accordingly (restricting them to wsize).
  726  * For the SYNC case, we can do this with 1 copy (user buffer -> mbuf). 
  727  * For the ASYNC case, 2 copies are needed. The first a copy from the 
  728  * user buffer to a staging buffer and then a second copy from the staging
  729  * buffer to mbufs. This can be optimized by copying from the user buffer
  730  * directly into mbufs and passing the chain down, but that requires a 
  731  * fair amount of re-working of the relevant codepaths (and can be done
  732  * later).
  733  */
  734 static int
  735 nfs_directio_write(vp, uiop, cred, ioflag)
  736         struct vnode *vp;
  737         struct uio *uiop;
  738         struct ucred *cred;
  739         int ioflag;
  740 {
  741         int error;
  742         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  743         struct thread *td = uiop->uio_td;
  744         int size;
  745         int wsize;
  746         
  747         mtx_lock(&nmp->nm_mtx);
  748         wsize = nmp->nm_wsize;
  749         mtx_unlock(&nmp->nm_mtx);
  750         if (ioflag & IO_SYNC) {
  751                 int iomode, must_commit;
  752                 struct uio uio;
  753                 struct iovec iov;
  754 do_sync:
  755                 while (uiop->uio_resid > 0) {
  756                         size = min(uiop->uio_resid, wsize);
  757                         size = min(uiop->uio_iov->iov_len, size);
  758                         iov.iov_base = uiop->uio_iov->iov_base;
  759                         iov.iov_len = size;
  760                         uio.uio_iov = &iov;
  761                         uio.uio_iovcnt = 1;
  762                         uio.uio_offset = uiop->uio_offset;
  763                         uio.uio_resid = size;
  764                         uio.uio_segflg = UIO_USERSPACE;
  765                         uio.uio_rw = UIO_WRITE;
  766                         uio.uio_td = td;
  767                         iomode = NFSV3WRITE_FILESYNC;
  768                         error = (nmp->nm_rpcops->nr_writerpc)(vp, &uio, cred, 
  769                                                       &iomode, &must_commit);
  770                         KASSERT((must_commit == 0), 
  771                                 ("nfs_directio_write: Did not commit write"));
  772                         if (error)
  773                                 return (error);
  774                         uiop->uio_offset += size;
  775                         uiop->uio_resid -= size;
  776                         if (uiop->uio_iov->iov_len <= size) {
  777                                 uiop->uio_iovcnt--;
  778                                 uiop->uio_iov++;
  779                         } else {
  780                                 uiop->uio_iov->iov_base = 
  781                                         (char *)uiop->uio_iov->iov_base + size;
  782                                 uiop->uio_iov->iov_len -= size;
  783                         }
  784                 }
  785         } else {
  786                 struct uio *t_uio;
  787                 struct iovec *t_iov;
  788                 struct buf *bp;
  789                 
  790                 /*
  791                  * Break up the write into blocksize chunks and hand these
  792                  * over to nfsiod's for write back.
  793                  * Unfortunately, this incurs a copy of the data. Since 
  794                  * the user could modify the buffer before the write is 
  795                  * initiated.
  796                  * 
  797                  * The obvious optimization here is that one of the 2 copies
  798                  * in the async write path can be eliminated by copying the
  799                  * data here directly into mbufs and passing the mbuf chain
  800                  * down. But that will require a fair amount of re-working
  801                  * of the code and can be done if there's enough interest
  802                  * in NFS directio access.
  803                  */
  804                 while (uiop->uio_resid > 0) {
  805                         size = min(uiop->uio_resid, wsize);
  806                         size = min(uiop->uio_iov->iov_len, size);
  807                         bp = getpbuf(&nfs_pbuf_freecnt);
  808                         t_uio = malloc(sizeof(struct uio), M_NFSDIRECTIO, M_WAITOK);
  809                         t_iov = malloc(sizeof(struct iovec), M_NFSDIRECTIO, M_WAITOK);
  810                         t_iov->iov_base = malloc(size, M_NFSDIRECTIO, M_WAITOK);
  811                         t_iov->iov_len = size;
  812                         t_uio->uio_iov = t_iov;
  813                         t_uio->uio_iovcnt = 1;
  814                         t_uio->uio_offset = uiop->uio_offset;
  815                         t_uio->uio_resid = size;
  816                         t_uio->uio_segflg = UIO_SYSSPACE;
  817                         t_uio->uio_rw = UIO_WRITE;
  818                         t_uio->uio_td = td;
  819                         bcopy(uiop->uio_iov->iov_base, t_iov->iov_base, size);
  820                         bp->b_flags |= B_DIRECT;
  821                         bp->b_iocmd = BIO_WRITE;
  822                         if (cred != NOCRED) {
  823                                 crhold(cred);
  824                                 bp->b_wcred = cred;
  825                         } else 
  826                                 bp->b_wcred = NOCRED;                   
  827                         bp->b_caller1 = (void *)t_uio;
  828                         bp->b_vp = vp;
  829                         error = nfs_asyncio(nmp, bp, NOCRED, td);
  830                         if (error) {
  831                                 free(t_iov->iov_base, M_NFSDIRECTIO);
  832                                 free(t_iov, M_NFSDIRECTIO);
  833                                 free(t_uio, M_NFSDIRECTIO);
  834                                 bp->b_vp = NULL;
  835                                 relpbuf(bp, &nfs_pbuf_freecnt);
  836                                 if (error == EINTR)
  837                                         return (error);
  838                                 goto do_sync;
  839                         }
  840                         uiop->uio_offset += size;
  841                         uiop->uio_resid -= size;
  842                         if (uiop->uio_iov->iov_len <= size) {
  843                                 uiop->uio_iovcnt--;
  844                                 uiop->uio_iov++;
  845                         } else {
  846                                 uiop->uio_iov->iov_base = 
  847                                         (char *)uiop->uio_iov->iov_base + size;
  848                                 uiop->uio_iov->iov_len -= size;
  849                         }
  850                 }
  851         }
  852         return (0);
  853 }
  854 
  855 /*
  856  * Vnode op for write using bio
  857  */
  858 int
  859 nfs_write(struct vop_write_args *ap)
  860 {
  861         int biosize;
  862         struct uio *uio = ap->a_uio;
  863         struct thread *td = uio->uio_td;
  864         struct vnode *vp = ap->a_vp;
  865         struct nfsnode *np = VTONFS(vp);
  866         struct ucred *cred = ap->a_cred;
  867         int ioflag = ap->a_ioflag;
  868         struct buf *bp;
  869         struct vattr vattr;
  870         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  871         daddr_t lbn;
  872         int bcount;
  873         int n, on, error = 0;
  874         struct proc *p = td?td->td_proc:NULL;
  875 
  876 #ifdef DIAGNOSTIC
  877         if (uio->uio_rw != UIO_WRITE)
  878                 panic("nfs_write mode");
  879         if (uio->uio_segflg == UIO_USERSPACE && uio->uio_td != curthread)
  880                 panic("nfs_write proc");
  881 #endif
  882         if (vp->v_type != VREG)
  883                 return (EIO);
  884         mtx_lock(&np->n_mtx);
  885         if (np->n_flag & NWRITEERR) {
  886                 np->n_flag &= ~NWRITEERR;
  887                 mtx_unlock(&np->n_mtx);
  888                 return (np->n_error);
  889         } else
  890                 mtx_unlock(&np->n_mtx);
  891         mtx_lock(&nmp->nm_mtx);
  892         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  893             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  894                 mtx_unlock(&nmp->nm_mtx);
  895                 (void)nfs_fsinfo(nmp, vp, cred, td);
  896         } else
  897                 mtx_unlock(&nmp->nm_mtx);
  898 
  899         /*
  900          * Synchronously flush pending buffers if we are in synchronous
  901          * mode or if we are appending.
  902          */
  903         if (ioflag & (IO_APPEND | IO_SYNC)) {
  904                 mtx_lock(&np->n_mtx);
  905                 if (np->n_flag & NMODIFIED) {
  906                         mtx_unlock(&np->n_mtx);
  907 #ifdef notyet /* Needs matching nonblock semantics elsewhere, too. */
  908                         /*
  909                          * Require non-blocking, synchronous writes to
  910                          * dirty files to inform the program it needs
  911                          * to fsync(2) explicitly.
  912                          */
  913                         if (ioflag & IO_NDELAY)
  914                                 return (EAGAIN);
  915 #endif
  916 flush_and_restart:
  917                         np->n_attrstamp = 0;
  918                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  919                         if (error)
  920                                 return (error);
  921                 } else
  922                         mtx_unlock(&np->n_mtx);
  923         }
  924 
  925         /*
  926          * If IO_APPEND then load uio_offset.  We restart here if we cannot
  927          * get the append lock.
  928          */
  929         if (ioflag & IO_APPEND) {
  930                 np->n_attrstamp = 0;
  931                 error = VOP_GETATTR(vp, &vattr, cred, td);
  932                 if (error)
  933                         return (error);
  934                 mtx_lock(&np->n_mtx);
  935                 uio->uio_offset = np->n_size;
  936                 mtx_unlock(&np->n_mtx);
  937         }
  938 
  939         if (uio->uio_offset < 0)
  940                 return (EINVAL);
  941         if ((uio->uio_offset + uio->uio_resid) > nmp->nm_maxfilesize)
  942                 return (EFBIG);
  943         if (uio->uio_resid == 0)
  944                 return (0);
  945 
  946         if (nfs_directio_enable && (ioflag & IO_DIRECT) && vp->v_type == VREG)
  947                 return nfs_directio_write(vp, uio, cred, ioflag);
  948 
  949         /*
  950          * Maybe this should be above the vnode op call, but so long as
  951          * file servers have no limits, i don't think it matters
  952          */
  953         if (p != NULL) {
  954                 PROC_LOCK(p);
  955                 if (uio->uio_offset + uio->uio_resid >
  956                     lim_cur(p, RLIMIT_FSIZE)) {
  957                         psignal(p, SIGXFSZ);
  958                         PROC_UNLOCK(p);
  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 nflag;
  975 
  976                 mtx_lock(&np->n_mtx);
  977                 nflag = np->n_flag;
  978                 mtx_unlock(&np->n_mtx);         
  979                 int needrestart = 0;
  980                 if (nmp->nm_wcommitsize < uio->uio_resid) {
  981                         /*
  982                          * If this request could not possibly be completed
  983                          * without exceeding the maximum outstanding write
  984                          * commit size, see if we can convert it into a
  985                          * synchronous write operation.
  986                          */
  987                         if (ioflag & IO_NDELAY)
  988                                 return (EAGAIN);
  989                         ioflag |= IO_SYNC;
  990                         if (nflag & NMODIFIED)
  991                                 needrestart = 1;
  992                 } else if (nflag & NMODIFIED) {
  993                         int wouldcommit = 0;
  994                         BO_LOCK(&vp->v_bufobj);
  995                         if (vp->v_bufobj.bo_dirty.bv_cnt != 0) {
  996                                 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd,
  997                                     b_bobufs) {
  998                                         if (bp->b_flags & B_NEEDCOMMIT)
  999                                                 wouldcommit += bp->b_bcount;
 1000                                 }
 1001                         }
 1002                         BO_UNLOCK(&vp->v_bufobj);
 1003                         /*
 1004                          * Since we're not operating synchronously and
 1005                          * bypassing the buffer cache, we are in a commit
 1006                          * and holding all of these buffers whether
 1007                          * transmitted or not.  If not limited, this
 1008                          * will lead to the buffer cache deadlocking,
 1009                          * as no one else can flush our uncommitted buffers.
 1010                          */
 1011                         wouldcommit += uio->uio_resid;
 1012                         /*
 1013                          * If we would initially exceed the maximum
 1014                          * outstanding write commit size, flush and restart.
 1015                          */
 1016                         if (wouldcommit > nmp->nm_wcommitsize)
 1017                                 needrestart = 1;
 1018                 }
 1019                 if (needrestart)
 1020                         goto flush_and_restart;
 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                 mtx_lock(&np->n_mtx);
 1034                 if (uio->uio_offset == np->n_size && n) {
 1035                         mtx_unlock(&np->n_mtx);
 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                                 mtx_lock(&np->n_mtx);
 1049                                 np->n_size = uio->uio_offset + n;
 1050                                 np->n_flag |= NMODIFIED;
 1051                                 vnode_pager_setsize(vp, np->n_size);
 1052                                 mtx_unlock(&np->n_mtx);
 1053 
 1054                                 save = bp->b_flags & B_CACHE;
 1055                                 bcount += n;
 1056                                 allocbuf(bp, bcount);
 1057                                 bp->b_flags |= save;
 1058                         }
 1059                 } else {
 1060                         /*
 1061                          * Obtain the locked cache block first, and then
 1062                          * adjust the file's size as appropriate.
 1063                          */
 1064                         bcount = on + n;
 1065                         if ((off_t)lbn * biosize + bcount < np->n_size) {
 1066                                 if ((off_t)(lbn + 1) * biosize < np->n_size)
 1067                                         bcount = biosize;
 1068                                 else
 1069                                         bcount = np->n_size - (off_t)lbn * biosize;
 1070                         }
 1071                         mtx_unlock(&np->n_mtx);
 1072                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1073                         mtx_lock(&np->n_mtx);
 1074                         if (uio->uio_offset + n > np->n_size) {
 1075                                 np->n_size = uio->uio_offset + n;
 1076                                 np->n_flag |= NMODIFIED;
 1077                                 vnode_pager_setsize(vp, np->n_size);
 1078                         }
 1079                         mtx_unlock(&np->n_mtx);
 1080                 }
 1081 
 1082                 if (!bp) {
 1083                         error = nfs_sigintr(nmp, NULL, td);
 1084                         if (!error)
 1085                                 error = EINTR;
 1086                         break;
 1087                 }
 1088 
 1089                 /*
 1090                  * Issue a READ if B_CACHE is not set.  In special-append
 1091                  * mode, B_CACHE is based on the buffer prior to the write
 1092                  * op and is typically set, avoiding the read.  If a read
 1093                  * is required in special append mode, the server will
 1094                  * probably send us a short-read since we extended the file
 1095                  * on our end, resulting in b_resid == 0 and, thusly,
 1096                  * B_CACHE getting set.
 1097                  *
 1098                  * We can also avoid issuing the read if the write covers
 1099                  * the entire buffer.  We have to make sure the buffer state
 1100                  * is reasonable in this case since we will not be initiating
 1101                  * I/O.  See the comments in kern/vfs_bio.c's getblk() for
 1102                  * more information.
 1103                  *
 1104                  * B_CACHE may also be set due to the buffer being cached
 1105                  * normally.
 1106                  */
 1107 
 1108                 if (on == 0 && n == bcount) {
 1109                         bp->b_flags |= B_CACHE;
 1110                         bp->b_flags &= ~B_INVAL;
 1111                         bp->b_ioflags &= ~BIO_ERROR;
 1112                 }
 1113 
 1114                 if ((bp->b_flags & B_CACHE) == 0) {
 1115                         bp->b_iocmd = BIO_READ;
 1116                         vfs_busy_pages(bp, 0);
 1117                         error = nfs_doio(vp, bp, cred, td);
 1118                         if (error) {
 1119                                 brelse(bp);
 1120                                 break;
 1121                         }
 1122                 }
 1123                 if (bp->b_wcred == NOCRED)
 1124                         bp->b_wcred = crhold(cred);
 1125                 mtx_lock(&np->n_mtx);
 1126                 np->n_flag |= NMODIFIED;
 1127                 mtx_unlock(&np->n_mtx);
 1128 
 1129                 /*
 1130                  * If dirtyend exceeds file size, chop it down.  This should
 1131                  * not normally occur but there is an append race where it
 1132                  * might occur XXX, so we log it.
 1133                  *
 1134                  * If the chopping creates a reverse-indexed or degenerate
 1135                  * situation with dirtyoff/end, we 0 both of them.
 1136                  */
 1137 
 1138                 if (bp->b_dirtyend > bcount) {
 1139                         nfs_printf("NFS append race @%lx:%d\n",
 1140                             (long)bp->b_blkno * DEV_BSIZE,
 1141                             bp->b_dirtyend - bcount);
 1142                         bp->b_dirtyend = bcount;
 1143                 }
 1144 
 1145                 if (bp->b_dirtyoff >= bp->b_dirtyend)
 1146                         bp->b_dirtyoff = bp->b_dirtyend = 0;
 1147 
 1148                 /*
 1149                  * If the new write will leave a contiguous dirty
 1150                  * area, just update the b_dirtyoff and b_dirtyend,
 1151                  * otherwise force a write rpc of the old dirty area.
 1152                  *
 1153                  * While it is possible to merge discontiguous writes due to
 1154                  * our having a B_CACHE buffer ( and thus valid read data
 1155                  * for the hole), we don't because it could lead to
 1156                  * significant cache coherency problems with multiple clients,
 1157                  * especially if locking is implemented later on.
 1158                  *
 1159                  * as an optimization we could theoretically maintain
 1160                  * a linked list of discontinuous areas, but we would still
 1161                  * have to commit them separately so there isn't much
 1162                  * advantage to it except perhaps a bit of asynchronization.
 1163                  */
 1164 
 1165                 if (bp->b_dirtyend > 0 &&
 1166                     (on > bp->b_dirtyend || (on + n) < bp->b_dirtyoff)) {
 1167                         if (bwrite(bp) == EINTR) {
 1168                                 error = EINTR;
 1169                                 break;
 1170                         }
 1171                         goto again;
 1172                 }
 1173 
 1174                 error = uiomove((char *)bp->b_data + on, n, uio);
 1175 
 1176                 /*
 1177                  * Since this block is being modified, it must be written
 1178                  * again and not just committed.  Since write clustering does
 1179                  * not work for the stage 1 data write, only the stage 2
 1180                  * commit rpc, we have to clear B_CLUSTEROK as well.
 1181                  */
 1182                 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1183 
 1184                 if (error) {
 1185                         bp->b_ioflags |= BIO_ERROR;
 1186                         brelse(bp);
 1187                         break;
 1188                 }
 1189 
 1190                 /*
 1191                  * Only update dirtyoff/dirtyend if not a degenerate
 1192                  * condition.
 1193                  */
 1194                 if (n) {
 1195                         if (bp->b_dirtyend > 0) {
 1196                                 bp->b_dirtyoff = min(on, bp->b_dirtyoff);
 1197                                 bp->b_dirtyend = max((on + n), bp->b_dirtyend);
 1198                         } else {
 1199                                 bp->b_dirtyoff = on;
 1200                                 bp->b_dirtyend = on + n;
 1201                         }
 1202                         vfs_bio_set_validclean(bp, on, n);
 1203                 }
 1204 
 1205                 /*
 1206                  * If IO_SYNC do bwrite().
 1207                  *
 1208                  * IO_INVAL appears to be unused.  The idea appears to be
 1209                  * to turn off caching in this case.  Very odd.  XXX
 1210                  */
 1211                 if ((ioflag & IO_SYNC)) {
 1212                         if (ioflag & IO_INVAL)
 1213                                 bp->b_flags |= B_NOCACHE;
 1214                         error = bwrite(bp);
 1215                         if (error)
 1216                                 break;
 1217                 } else if ((n + on) == biosize) {
 1218                         bp->b_flags |= B_ASYNC;
 1219                         (void) (nmp->nm_rpcops->nr_writebp)(bp, 0, NULL);
 1220                 } else {
 1221                         bdwrite(bp);
 1222                 }
 1223         } while (uio->uio_resid > 0 && n > 0);
 1224 
 1225         return (error);
 1226 }
 1227 
 1228 /*
 1229  * Get an nfs cache block.
 1230  *
 1231  * Allocate a new one if the block isn't currently in the cache
 1232  * and return the block marked busy. If the calling process is
 1233  * interrupted by a signal for an interruptible mount point, return
 1234  * NULL.
 1235  *
 1236  * The caller must carefully deal with the possible B_INVAL state of
 1237  * the buffer.  nfs_doio() clears B_INVAL (and nfs_asyncio() clears it
 1238  * indirectly), so synchronous reads can be issued without worrying about
 1239  * the B_INVAL state.  We have to be a little more careful when dealing
 1240  * with writes (see comments in nfs_write()) when extending a file past
 1241  * its EOF.
 1242  */
 1243 static struct buf *
 1244 nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size, struct thread *td)
 1245 {
 1246         struct buf *bp;
 1247         struct mount *mp;
 1248         struct nfsmount *nmp;
 1249 
 1250         mp = vp->v_mount;
 1251         nmp = VFSTONFS(mp);
 1252 
 1253         if (nmp->nm_flag & NFSMNT_INT) {
 1254                 sigset_t oldset;
 1255 
 1256                 nfs_set_sigmask(td, &oldset);
 1257                 bp = getblk(vp, bn, size, PCATCH, 0, 0);
 1258                 nfs_restore_sigmask(td, &oldset);
 1259                 while (bp == NULL) {
 1260                         if (nfs_sigintr(nmp, NULL, td))
 1261                                 return (NULL);
 1262                         bp = getblk(vp, bn, size, 0, 2 * hz, 0);
 1263                 }
 1264         } else {
 1265                 bp = getblk(vp, bn, size, 0, 0, 0);
 1266         }
 1267 
 1268         if (vp->v_type == VREG) {
 1269                 int biosize;
 1270 
 1271                 biosize = mp->mnt_stat.f_iosize;
 1272                 bp->b_blkno = bn * (biosize / DEV_BSIZE);
 1273         }
 1274         return (bp);
 1275 }
 1276 
 1277 /*
 1278  * Flush and invalidate all dirty buffers. If another process is already
 1279  * doing the flush, just wait for completion.
 1280  */
 1281 int
 1282 nfs_vinvalbuf(struct vnode *vp, int flags, struct thread *td, int intrflg)
 1283 {
 1284         struct nfsnode *np = VTONFS(vp);
 1285         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
 1286         int error = 0, slpflag, slptimeo;
 1287         int old_lock = 0;
 1288 
 1289         ASSERT_VOP_LOCKED(vp, "nfs_vinvalbuf");
 1290 
 1291         /*
 1292          * XXX This check stops us from needlessly doing a vinvalbuf when
 1293          * being called through vclean().  It is not clear that this is
 1294          * unsafe.
 1295          */
 1296         if (vp->v_iflag & VI_DOOMED)
 1297                 return (0);
 1298 
 1299         if ((nmp->nm_flag & NFSMNT_INT) == 0)
 1300                 intrflg = 0;
 1301         if (intrflg) {
 1302                 slpflag = PCATCH;
 1303                 slptimeo = 2 * hz;
 1304         } else {
 1305                 slpflag = 0;
 1306                 slptimeo = 0;
 1307         }
 1308 
 1309         old_lock = nfs_upgrade_vnlock(vp, td);
 1310         /*
 1311          * Now, flush as required.
 1312          */
 1313         if ((flags & V_SAVE) && (vp->v_bufobj.bo_object != NULL)) {
 1314                 VM_OBJECT_LOCK(vp->v_bufobj.bo_object);
 1315                 vm_object_page_clean(vp->v_bufobj.bo_object, 0, 0, OBJPC_SYNC);
 1316                 VM_OBJECT_UNLOCK(vp->v_bufobj.bo_object);
 1317                 /*
 1318                  * If the page clean was interrupted, fail the invalidation.
 1319                  * Not doing so, we run the risk of losing dirty pages in the 
 1320                  * vinvalbuf() call below.
 1321                  */
 1322                 if (intrflg && (error = nfs_sigintr(nmp, NULL, td)))
 1323                         goto out;
 1324         }
 1325 
 1326         error = vinvalbuf(vp, flags, td, slpflag, 0);
 1327         while (error) {
 1328                 if (intrflg && (error = nfs_sigintr(nmp, NULL, td)))
 1329                         goto out;
 1330                 error = vinvalbuf(vp, flags, td, 0, slptimeo);
 1331         }
 1332         mtx_lock(&np->n_mtx);
 1333         if (np->n_directio_asyncwr == 0)
 1334                 np->n_flag &= ~NMODIFIED;
 1335         mtx_unlock(&np->n_mtx);
 1336 out:
 1337         nfs_downgrade_vnlock(vp, td, old_lock);
 1338         return error;
 1339 }
 1340 
 1341 /*
 1342  * Initiate asynchronous I/O. Return an error if no nfsiods are available.
 1343  * This is mainly to avoid queueing async I/O requests when the nfsiods
 1344  * are all hung on a dead server.
 1345  *
 1346  * Note: nfs_asyncio() does not clear (BIO_ERROR|B_INVAL) but when the bp
 1347  * is eventually dequeued by the async daemon, nfs_doio() *will*.
 1348  */
 1349 int
 1350 nfs_asyncio(struct nfsmount *nmp, struct buf *bp, struct ucred *cred, struct thread *td)
 1351 {
 1352         int iod;
 1353         int gotiod;
 1354         int slpflag = 0;
 1355         int slptimeo = 0;
 1356         int error, error2;
 1357 
 1358         /*
 1359          * Commits are usually short and sweet so lets save some cpu and
 1360          * leave the async daemons for more important rpc's (such as reads
 1361          * and writes).
 1362          */
 1363         mtx_lock(&nfs_iod_mtx);
 1364         if (bp->b_iocmd == BIO_WRITE && (bp->b_flags & B_NEEDCOMMIT) &&
 1365             (nmp->nm_bufqiods > nfs_numasync / 2)) {
 1366                 mtx_unlock(&nfs_iod_mtx);
 1367                 return(EIO);
 1368         }
 1369 again:
 1370         if (nmp->nm_flag & NFSMNT_INT)
 1371                 slpflag = PCATCH;
 1372         gotiod = FALSE;
 1373 
 1374         /*
 1375          * Find a free iod to process this request.
 1376          */
 1377         for (iod = 0; iod < nfs_numasync; iod++)
 1378                 if (nfs_iodwant[iod] == NFSIOD_AVAILABLE) {
 1379                         gotiod = TRUE;
 1380                         break;
 1381                 }
 1382 
 1383         /*
 1384          * Try to create one if none are free.
 1385          */
 1386         if (!gotiod)
 1387                 nfs_nfsiodnew();
 1388         else {
 1389                 /*
 1390                  * Found one, so wake it up and tell it which
 1391                  * mount to process.
 1392                  */
 1393                 NFS_DPF(ASYNCIO, ("nfs_asyncio: waking iod %d for mount %p\n",
 1394                     iod, nmp));
 1395                 nfs_iodwant[iod] = NFSIOD_NOT_AVAILABLE;
 1396                 nfs_iodmount[iod] = nmp;
 1397                 nmp->nm_bufqiods++;
 1398                 wakeup(&nfs_iodwant[iod]);
 1399         }
 1400 
 1401         /*
 1402          * If none are free, we may already have an iod working on this mount
 1403          * point.  If so, it will process our request.
 1404          */
 1405         if (!gotiod) {
 1406                 if (nmp->nm_bufqiods > 0) {
 1407                         NFS_DPF(ASYNCIO,
 1408                 ("nfs_asyncio: %d iods are already processing mount %p\n",
 1409                                  nmp->nm_bufqiods, nmp));
 1410                         gotiod = TRUE;
 1411                 }
 1412         }
 1413 
 1414         /*
 1415          * If we have an iod which can process the request, then queue
 1416          * the buffer.
 1417          */
 1418         if (gotiod) {
 1419                 /*
 1420                  * Ensure that the queue never grows too large.  We still want
 1421                  * to asynchronize so we block rather then return EIO.
 1422                  */
 1423                 while (nmp->nm_bufqlen >= 2 * nfs_numasync) {
 1424                         NFS_DPF(ASYNCIO,
 1425                 ("nfs_asyncio: waiting for mount %p queue to drain\n", nmp));
 1426                         nmp->nm_bufqwant = TRUE;
 1427                         error = nfs_msleep(td, &nmp->nm_bufq, &nfs_iod_mtx, 
 1428                                            slpflag | PRIBIO,
 1429                                            "nfsaio", slptimeo);
 1430                         if (error) {
 1431                                 error2 = nfs_sigintr(nmp, NULL, td);
 1432                                 if (error2) {
 1433                                         mtx_unlock(&nfs_iod_mtx);
 1434                                         return (error2);
 1435                                 }
 1436                                 if (slpflag == PCATCH) {
 1437                                         slpflag = 0;
 1438                                         slptimeo = 2 * hz;
 1439                                 }
 1440                         }
 1441                         /*
 1442                          * We might have lost our iod while sleeping,
 1443                          * so check and loop if nescessary.
 1444                          */
 1445                         goto again;
 1446                 }
 1447 
 1448                 /* We might have lost our nfsiod */
 1449                 if (nmp->nm_bufqiods == 0) {
 1450                         NFS_DPF(ASYNCIO,
 1451 ("nfs_asyncio: no iods after mount %p queue was drained, looping\n", nmp));
 1452                         goto again;
 1453                 }
 1454 
 1455                 if (bp->b_iocmd == BIO_READ) {
 1456                         if (bp->b_rcred == NOCRED && cred != NOCRED)
 1457                                 bp->b_rcred = crhold(cred);
 1458                 } else {
 1459                         if (bp->b_wcred == NOCRED && cred != NOCRED)
 1460                                 bp->b_wcred = crhold(cred);
 1461                 }
 1462 
 1463                 if (bp->b_flags & B_REMFREE)
 1464                         bremfreef(bp);
 1465                 BUF_KERNPROC(bp);
 1466                 TAILQ_INSERT_TAIL(&nmp->nm_bufq, bp, b_freelist);
 1467                 nmp->nm_bufqlen++;
 1468                 if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1469                         mtx_lock(&(VTONFS(bp->b_vp))->n_mtx);                   
 1470                         VTONFS(bp->b_vp)->n_flag |= NMODIFIED;
 1471                         VTONFS(bp->b_vp)->n_directio_asyncwr++;
 1472                         mtx_unlock(&(VTONFS(bp->b_vp))->n_mtx);
 1473                 }
 1474                 mtx_unlock(&nfs_iod_mtx);
 1475                 return (0);
 1476         }
 1477 
 1478         mtx_unlock(&nfs_iod_mtx);
 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                 mtx_lock(&np->n_mtx);
 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                 mtx_unlock(&np->n_mtx);
 1515         }
 1516         bp->b_vp = NULL;
 1517         relpbuf(bp, &nfs_pbuf_freecnt);
 1518 }
 1519 
 1520 /*
 1521  * Do an I/O operation to/from a cache block. This may be called
 1522  * synchronously or from an nfsiod.
 1523  */
 1524 int
 1525 nfs_doio(struct vnode *vp, struct buf *bp, struct ucred *cr, struct thread *td)
 1526 {
 1527         struct uio *uiop;
 1528         struct nfsnode *np;
 1529         struct nfsmount *nmp;
 1530         int error = 0, iomode, must_commit = 0;
 1531         struct uio uio;
 1532         struct iovec io;
 1533         struct proc *p = td ? td->td_proc : NULL;
 1534         uint8_t iocmd;
 1535         
 1536         np = VTONFS(vp);
 1537         nmp = VFSTONFS(vp->v_mount);
 1538         uiop = &uio;
 1539         uiop->uio_iov = &io;
 1540         uiop->uio_iovcnt = 1;
 1541         uiop->uio_segflg = UIO_SYSSPACE;
 1542         uiop->uio_td = td;
 1543 
 1544         /*
 1545          * clear BIO_ERROR and B_INVAL state prior to initiating the I/O.  We
 1546          * do this here so we do not have to do it in all the code that
 1547          * calls us.
 1548          */
 1549         bp->b_flags &= ~B_INVAL;
 1550         bp->b_ioflags &= ~BIO_ERROR;
 1551 
 1552         KASSERT(!(bp->b_flags & B_DONE), ("nfs_doio: bp %p already marked done", bp));
 1553         iocmd = bp->b_iocmd;
 1554         if (iocmd == BIO_READ) {
 1555             io.iov_len = uiop->uio_resid = bp->b_bcount;
 1556             io.iov_base = bp->b_data;
 1557             uiop->uio_rw = UIO_READ;
 1558 
 1559             switch (vp->v_type) {
 1560             case VREG:
 1561                 uiop->uio_offset = ((off_t)bp->b_blkno) * DEV_BSIZE;
 1562                 nfsstats.read_bios++;
 1563                 error = (nmp->nm_rpcops->nr_readrpc)(vp, uiop, cr);
 1564 
 1565                 if (!error) {
 1566                     if (uiop->uio_resid) {
 1567                         /*
 1568                          * If we had a short read with no error, we must have
 1569                          * hit a file hole.  We should zero-fill the remainder.
 1570                          * This can also occur if the server hits the file EOF.
 1571                          *
 1572                          * Holes used to be able to occur due to pending
 1573                          * writes, but that is not possible any longer.
 1574                          */
 1575                         int nread = bp->b_bcount - uiop->uio_resid;
 1576                         int left  = uiop->uio_resid;
 1577 
 1578                         if (left > 0)
 1579                                 bzero((char *)bp->b_data + nread, left);
 1580                         uiop->uio_resid = 0;
 1581                     }
 1582                 }
 1583                 /* ASSERT_VOP_LOCKED(vp, "nfs_doio"); */
 1584                 if (p && (vp->v_vflag & VV_TEXT)) {
 1585                         mtx_lock(&np->n_mtx);
 1586                         if (NFS_TIMESPEC_COMPARE(&np->n_mtime, &np->n_vattr.va_mtime)) {
 1587                                 mtx_unlock(&np->n_mtx);
 1588                                 PROC_LOCK(p);
 1589                                 killproc(p, "text file modification");
 1590                                 PROC_UNLOCK(p);
 1591                         } else
 1592                                 mtx_unlock(&np->n_mtx);
 1593                 }
 1594                 break;
 1595             case VLNK:
 1596                 uiop->uio_offset = (off_t)0;
 1597                 nfsstats.readlink_bios++;
 1598                 error = (nmp->nm_rpcops->nr_readlinkrpc)(vp, uiop, cr);
 1599                 break;
 1600             case VDIR:
 1601                 nfsstats.readdir_bios++;
 1602                 uiop->uio_offset = ((u_quad_t)bp->b_lblkno) * NFS_DIRBLKSIZ;
 1603                 if ((nmp->nm_flag & NFSMNT_NFSV4) != 0)
 1604                         error = nfs4_readdirrpc(vp, uiop, cr);
 1605                 else {
 1606                         if ((nmp->nm_flag & NFSMNT_RDIRPLUS) != 0) {
 1607                                 error = nfs_readdirplusrpc(vp, uiop, cr);
 1608                                 if (error == NFSERR_NOTSUPP)
 1609                                         nmp->nm_flag &= ~NFSMNT_RDIRPLUS;
 1610                         }
 1611                         if ((nmp->nm_flag & NFSMNT_RDIRPLUS) == 0)
 1612                                 error = nfs_readdirrpc(vp, uiop, cr);
 1613                 }
 1614                 /*
 1615                  * end-of-directory sets B_INVAL but does not generate an
 1616                  * error.
 1617                  */
 1618                 if (error == 0 && uiop->uio_resid == bp->b_bcount)
 1619                         bp->b_flags |= B_INVAL;
 1620                 break;
 1621             default:
 1622                 nfs_printf("nfs_doio:  type %x unexpected\n", vp->v_type);
 1623                 break;
 1624             };
 1625             if (error) {
 1626                 bp->b_ioflags |= BIO_ERROR;
 1627                 bp->b_error = error;
 1628             }
 1629         } else {
 1630             /*
 1631              * If we only need to commit, try to commit
 1632              */
 1633             if (bp->b_flags & B_NEEDCOMMIT) {
 1634                     int retv;
 1635                     off_t off;
 1636 
 1637                     off = ((u_quad_t)bp->b_blkno) * DEV_BSIZE + bp->b_dirtyoff;
 1638                     retv = (nmp->nm_rpcops->nr_commit)(
 1639                                 vp, off, bp->b_dirtyend-bp->b_dirtyoff,
 1640                                 bp->b_wcred, td);
 1641                     if (retv == 0) {
 1642                             bp->b_dirtyoff = bp->b_dirtyend = 0;
 1643                             bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1644                             bp->b_resid = 0;
 1645                             bufdone(bp);
 1646                             return (0);
 1647                     }
 1648                     if (retv == NFSERR_STALEWRITEVERF) {
 1649                             nfs_clearcommit(vp->v_mount);
 1650                     }
 1651             }
 1652 
 1653             /*
 1654              * Setup for actual write
 1655              */
 1656             mtx_lock(&np->n_mtx);
 1657             if ((off_t)bp->b_blkno * DEV_BSIZE + bp->b_dirtyend > np->n_size)
 1658                 bp->b_dirtyend = np->n_size - (off_t)bp->b_blkno * DEV_BSIZE;
 1659             mtx_unlock(&np->n_mtx);
 1660 
 1661             if (bp->b_dirtyend > bp->b_dirtyoff) {
 1662                 io.iov_len = uiop->uio_resid = bp->b_dirtyend
 1663                     - bp->b_dirtyoff;
 1664                 uiop->uio_offset = (off_t)bp->b_blkno * DEV_BSIZE
 1665                     + bp->b_dirtyoff;
 1666                 io.iov_base = (char *)bp->b_data + bp->b_dirtyoff;
 1667                 uiop->uio_rw = UIO_WRITE;
 1668                 nfsstats.write_bios++;
 1669 
 1670                 if ((bp->b_flags & (B_ASYNC | B_NEEDCOMMIT | B_NOCACHE | B_CLUSTER)) == B_ASYNC)
 1671                     iomode = NFSV3WRITE_UNSTABLE;
 1672                 else
 1673                     iomode = NFSV3WRITE_FILESYNC;
 1674 
 1675                 error = (nmp->nm_rpcops->nr_writerpc)(vp, uiop, cr, &iomode, &must_commit);
 1676 
 1677                 /*
 1678                  * When setting B_NEEDCOMMIT also set B_CLUSTEROK to try
 1679                  * to cluster the buffers needing commit.  This will allow
 1680                  * the system to submit a single commit rpc for the whole
 1681                  * cluster.  We can do this even if the buffer is not 100%
 1682                  * dirty (relative to the NFS blocksize), so we optimize the
 1683                  * append-to-file-case.
 1684                  *
 1685                  * (when clearing B_NEEDCOMMIT, B_CLUSTEROK must also be
 1686                  * cleared because write clustering only works for commit
 1687                  * rpc's, not for the data portion of the write).
 1688                  */
 1689 
 1690                 if (!error && iomode == NFSV3WRITE_UNSTABLE) {
 1691                     bp->b_flags |= B_NEEDCOMMIT;
 1692                     if (bp->b_dirtyoff == 0
 1693                         && bp->b_dirtyend == bp->b_bcount)
 1694                         bp->b_flags |= B_CLUSTEROK;
 1695                 } else {
 1696                     bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1697                 }
 1698 
 1699                 /*
 1700                  * For an interrupted write, the buffer is still valid
 1701                  * and the write hasn't been pushed to the server yet,
 1702                  * so we can't set BIO_ERROR and report the interruption
 1703                  * by setting B_EINTR. For the B_ASYNC case, B_EINTR
 1704                  * is not relevant, so the rpc attempt is essentially
 1705                  * a noop.  For the case of a V3 write rpc not being
 1706                  * committed to stable storage, the block is still
 1707                  * dirty and requires either a commit rpc or another
 1708                  * write rpc with iomode == NFSV3WRITE_FILESYNC before
 1709                  * the block is reused. This is indicated by setting
 1710                  * the B_DELWRI and B_NEEDCOMMIT flags.
 1711                  *
 1712                  * If the buffer is marked B_PAGING, it does not reside on
 1713                  * the vp's paging queues so we cannot call bdirty().  The
 1714                  * bp in this case is not an NFS cache block so we should
 1715                  * be safe. XXX
 1716                  *
 1717                  * The logic below breaks up errors into recoverable and 
 1718                  * unrecoverable. For the former, we clear B_INVAL|B_NOCACHE
 1719                  * and keep the buffer around for potential write retries.
 1720                  * For the latter (eg ESTALE), we toss the buffer away (B_INVAL)
 1721                  * and save the error in the nfsnode. This is less than ideal 
 1722                  * but necessary. Keeping such buffers around could potentially
 1723                  * cause buffer exhaustion eventually (they can never be written
 1724                  * out, so will get constantly be re-dirtied). It also causes
 1725                  * all sorts of vfs panics. For non-recoverable write errors, 
 1726                  * also invalidate the attrcache, so we'll be forced to go over
 1727                  * the wire for this object, returning an error to user on next
 1728                  * call (most of the time).
 1729                  */
 1730                 if (error == EINTR || error == EIO || error == ETIMEDOUT
 1731                     || (!error && (bp->b_flags & B_NEEDCOMMIT))) {
 1732                         int s;
 1733 
 1734                         s = splbio();
 1735                         bp->b_flags &= ~(B_INVAL|B_NOCACHE);
 1736                         if ((bp->b_flags & B_PAGING) == 0) {
 1737                             bdirty(bp);
 1738                             bp->b_flags &= ~B_DONE;
 1739                         }
 1740                         if (error && (bp->b_flags & B_ASYNC) == 0)
 1741                             bp->b_flags |= B_EINTR;
 1742                         splx(s);
 1743                 } else {
 1744                     if (error) {
 1745                         bp->b_ioflags |= BIO_ERROR;
 1746                         bp->b_flags |= B_INVAL;
 1747                         bp->b_error = np->n_error = error;
 1748                         mtx_lock(&np->n_mtx);
 1749                         np->n_flag |= NWRITEERR;
 1750                         np->n_attrstamp = 0;
 1751                         mtx_unlock(&np->n_mtx);
 1752                     }
 1753                     bp->b_dirtyoff = bp->b_dirtyend = 0;
 1754                 }
 1755             } else {
 1756                 bp->b_resid = 0;
 1757                 bufdone(bp);
 1758                 return (0);
 1759             }
 1760         }
 1761         bp->b_resid = uiop->uio_resid;
 1762         if (must_commit)
 1763             nfs_clearcommit(vp->v_mount);
 1764         bufdone(bp);
 1765         return (error);
 1766 }
 1767 
 1768 /*
 1769  * Used to aid in handling ftruncate() operations on the NFS client side.
 1770  * Truncation creates a number of special problems for NFS.  We have to
 1771  * throw away VM pages and buffer cache buffers that are beyond EOF, and
 1772  * we have to properly handle VM pages or (potentially dirty) buffers
 1773  * that straddle the truncation point.
 1774  */
 1775 
 1776 int
 1777 nfs_meta_setsize(struct vnode *vp, struct ucred *cred, struct thread *td, u_quad_t nsize)
 1778 {
 1779         struct nfsnode *np = VTONFS(vp);
 1780         u_quad_t tsize;
 1781         int biosize = vp->v_mount->mnt_stat.f_iosize;
 1782         int error = 0;
 1783 
 1784         mtx_lock(&np->n_mtx);
 1785         tsize = np->n_size;
 1786         np->n_size = nsize;
 1787         mtx_unlock(&np->n_mtx);
 1788 
 1789         if (nsize < tsize) {
 1790                 struct buf *bp;
 1791                 daddr_t lbn;
 1792                 int bufsize;
 1793 
 1794                 /*
 1795                  * vtruncbuf() doesn't get the buffer overlapping the 
 1796                  * truncation point.  We may have a B_DELWRI and/or B_CACHE
 1797                  * buffer that now needs to be truncated.
 1798                  */
 1799                 error = vtruncbuf(vp, cred, td, nsize, biosize);
 1800                 lbn = nsize / biosize;
 1801                 bufsize = nsize & (biosize - 1);
 1802                 bp = nfs_getcacheblk(vp, lbn, bufsize, td);
 1803                 if (!bp)
 1804                         return EINTR;
 1805                 if (bp->b_dirtyoff > bp->b_bcount)
 1806                         bp->b_dirtyoff = bp->b_bcount;
 1807                 if (bp->b_dirtyend > bp->b_bcount)
 1808                         bp->b_dirtyend = bp->b_bcount;
 1809                 bp->b_flags |= B_RELBUF;  /* don't leave garbage around */
 1810                 brelse(bp);
 1811         } else {
 1812                 vnode_pager_setsize(vp, nsize);
 1813         }
 1814         return(error);
 1815 }
 1816 

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