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/8.3/sys/nfsclient/nfs_bio.c 231332 2012-02-10 04:01:17Z rmacklem $");
   37 
   38 #include "opt_kdtrace.h"
   39 
   40 #include <sys/param.h>
   41 #include <sys/systm.h>
   42 #include <sys/bio.h>
   43 #include <sys/buf.h>
   44 #include <sys/kernel.h>
   45 #include <sys/mbuf.h>
   46 #include <sys/mount.h>
   47 #include <sys/proc.h>
   48 #include <sys/vmmeter.h>
   49 #include <sys/vnode.h>
   50 
   51 #include <vm/vm.h>
   52 #include <vm/vm_extern.h>
   53 #include <vm/vm_page.h>
   54 #include <vm/vm_object.h>
   55 #include <vm/vm_pager.h>
   56 #include <vm/vnode_pager.h>
   57 
   58 #include <nfs/nfsproto.h>
   59 #include <nfsclient/nfs.h>
   60 #include <nfsclient/nfsmount.h>
   61 #include <nfsclient/nfsnode.h>
   62 #include <nfsclient/nfs_kdtrace.h>
   63 
   64 static struct buf *nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size,
   65                     struct thread *td);
   66 static int nfs_directio_write(struct vnode *vp, struct uio *uiop, 
   67                               struct ucred *cred, int ioflag);
   68 
   69 extern int nfs_directio_enable;
   70 extern int nfs_directio_allow_mmap;
   71 
   72 /*
   73  * Vnode op for VM getpages.
   74  */
   75 int
   76 nfs_getpages(struct vop_getpages_args *ap)
   77 {
   78         int i, error, nextoff, size, toff, count, npages;
   79         struct uio uio;
   80         struct iovec iov;
   81         vm_offset_t kva;
   82         struct buf *bp;
   83         struct vnode *vp;
   84         struct thread *td;
   85         struct ucred *cred;
   86         struct nfsmount *nmp;
   87         vm_object_t object;
   88         vm_page_t *pages;
   89         struct nfsnode *np;
   90 
   91         vp = ap->a_vp;
   92         np = VTONFS(vp);
   93         td = curthread;                         /* XXX */
   94         cred = curthread->td_ucred;             /* XXX */
   95         nmp = VFSTONFS(vp->v_mount);
   96         pages = ap->a_m;
   97         count = ap->a_count;
   98 
   99         if ((object = vp->v_object) == NULL) {
  100                 nfs_printf("nfs_getpages: called with non-merged cache vnode??\n");
  101                 return (VM_PAGER_ERROR);
  102         }
  103 
  104         if (nfs_directio_enable && !nfs_directio_allow_mmap) {
  105                 mtx_lock(&np->n_mtx);
  106                 if ((np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
  107                         mtx_unlock(&np->n_mtx);
  108                         nfs_printf("nfs_getpages: called on non-cacheable vnode??\n");
  109                         return (VM_PAGER_ERROR);
  110                 } else
  111                         mtx_unlock(&np->n_mtx);
  112         }
  113 
  114         mtx_lock(&nmp->nm_mtx);
  115         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  116             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {  
  117                 mtx_unlock(&nmp->nm_mtx);
  118                 /* We'll never get here for v4, because we always have fsinfo */
  119                 (void)nfs_fsinfo(nmp, vp, cred, td);
  120         } else
  121                 mtx_unlock(&nmp->nm_mtx);
  122 
  123         npages = btoc(count);
  124 
  125         /*
  126          * If the requested page is partially valid, just return it and
  127          * allow the pager to zero-out the blanks.  Partially valid pages
  128          * can only occur at the file EOF.
  129          */
  130         VM_OBJECT_LOCK(object);
  131         if (pages[ap->a_reqpage]->valid != 0) {
  132                 vm_page_lock_queues();
  133                 for (i = 0; i < npages; ++i) {
  134                         if (i != ap->a_reqpage)
  135                                 vm_page_free(pages[i]);
  136                 }
  137                 vm_page_unlock_queues();
  138                 VM_OBJECT_UNLOCK(object);
  139                 return (0);
  140         }
  141         VM_OBJECT_UNLOCK(object);
  142 
  143         /*
  144          * We use only the kva address for the buffer, but this is extremely
  145          * convienient and fast.
  146          */
  147         bp = getpbuf(&nfs_pbuf_freecnt);
  148 
  149         kva = (vm_offset_t) bp->b_data;
  150         pmap_qenter(kva, pages, npages);
  151         PCPU_INC(cnt.v_vnodein);
  152         PCPU_ADD(cnt.v_vnodepgsin, npages);
  153 
  154         iov.iov_base = (caddr_t) kva;
  155         iov.iov_len = count;
  156         uio.uio_iov = &iov;
  157         uio.uio_iovcnt = 1;
  158         uio.uio_offset = IDX_TO_OFF(pages[0]->pindex);
  159         uio.uio_resid = count;
  160         uio.uio_segflg = UIO_SYSSPACE;
  161         uio.uio_rw = UIO_READ;
  162         uio.uio_td = td;
  163 
  164         error = (nmp->nm_rpcops->nr_readrpc)(vp, &uio, cred);
  165         pmap_qremove(kva, npages);
  166 
  167         relpbuf(bp, &nfs_pbuf_freecnt);
  168 
  169         if (error && (uio.uio_resid == count)) {
  170                 nfs_printf("nfs_getpages: error %d\n", error);
  171                 VM_OBJECT_LOCK(object);
  172                 vm_page_lock_queues();
  173                 for (i = 0; i < npages; ++i) {
  174                         if (i != ap->a_reqpage)
  175                                 vm_page_free(pages[i]);
  176                 }
  177                 vm_page_unlock_queues();
  178                 VM_OBJECT_UNLOCK(object);
  179                 return (VM_PAGER_ERROR);
  180         }
  181 
  182         /*
  183          * Calculate the number of bytes read and validate only that number
  184          * of bytes.  Note that due to pending writes, size may be 0.  This
  185          * does not mean that the remaining data is invalid!
  186          */
  187 
  188         size = count - uio.uio_resid;
  189         VM_OBJECT_LOCK(object);
  190         vm_page_lock_queues();
  191         for (i = 0, toff = 0; i < npages; i++, toff = nextoff) {
  192                 vm_page_t m;
  193                 nextoff = toff + PAGE_SIZE;
  194                 m = pages[i];
  195 
  196                 if (nextoff <= size) {
  197                         /*
  198                          * Read operation filled an entire page
  199                          */
  200                         m->valid = VM_PAGE_BITS_ALL;
  201                         KASSERT(m->dirty == 0,
  202                             ("nfs_getpages: page %p is dirty", m));
  203                 } else if (size > toff) {
  204                         /*
  205                          * Read operation filled a partial page.
  206                          */
  207                         m->valid = 0;
  208                         vm_page_set_valid(m, 0, size - toff);
  209                         KASSERT(m->dirty == 0,
  210                             ("nfs_getpages: page %p is dirty", m));
  211                 } else {
  212                         /*
  213                          * Read operation was short.  If no error occured
  214                          * we may have hit a zero-fill section.   We simply
  215                          * leave valid set to 0.
  216                          */
  217                         ;
  218                 }
  219                 if (i != ap->a_reqpage) {
  220                         /*
  221                          * Whether or not to leave the page activated is up in
  222                          * the air, but we should put the page on a page queue
  223                          * somewhere (it already is in the object).  Result:
  224                          * It appears that emperical results show that
  225                          * deactivating pages is best.
  226                          */
  227 
  228                         /*
  229                          * Just in case someone was asking for this page we
  230                          * now tell them that it is ok to use.
  231                          */
  232                         if (!error) {
  233                                 if (m->oflags & VPO_WANTED)
  234                                         vm_page_activate(m);
  235                                 else
  236                                         vm_page_deactivate(m);
  237                                 vm_page_wakeup(m);
  238                         } else {
  239                                 vm_page_free(m);
  240                         }
  241                 }
  242         }
  243         vm_page_unlock_queues();
  244         VM_OBJECT_UNLOCK(object);
  245         return (0);
  246 }
  247 
  248 /*
  249  * Vnode op for VM putpages.
  250  */
  251 int
  252 nfs_putpages(struct vop_putpages_args *ap)
  253 {
  254         struct uio uio;
  255         struct iovec iov;
  256         vm_offset_t kva;
  257         struct buf *bp;
  258         int iomode, must_commit, i, error, npages, count;
  259         off_t offset;
  260         int *rtvals;
  261         struct vnode *vp;
  262         struct thread *td;
  263         struct ucred *cred;
  264         struct nfsmount *nmp;
  265         struct nfsnode *np;
  266         vm_page_t *pages;
  267 
  268         vp = ap->a_vp;
  269         np = VTONFS(vp);
  270         td = curthread;                         /* XXX */
  271         cred = curthread->td_ucred;             /* XXX */
  272         nmp = VFSTONFS(vp->v_mount);
  273         pages = ap->a_m;
  274         count = ap->a_count;
  275         rtvals = ap->a_rtvals;
  276         npages = btoc(count);
  277         offset = IDX_TO_OFF(pages[0]->pindex);
  278         
  279         mtx_lock(&nmp->nm_mtx);
  280         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  281             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  282                 mtx_unlock(&nmp->nm_mtx);
  283                 (void)nfs_fsinfo(nmp, vp, cred, td);
  284         } else
  285                 mtx_unlock(&nmp->nm_mtx);
  286 
  287         mtx_lock(&np->n_mtx);
  288         if (nfs_directio_enable && !nfs_directio_allow_mmap && 
  289             (np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
  290                 mtx_unlock(&np->n_mtx);         
  291                 nfs_printf("nfs_putpages: called on noncache-able vnode??\n");
  292                 mtx_lock(&np->n_mtx);
  293         }
  294 
  295         for (i = 0; i < npages; i++)
  296                 rtvals[i] = VM_PAGER_ERROR;
  297 
  298         /*
  299          * When putting pages, do not extend file past EOF.
  300          */
  301         if (offset + count > np->n_size) {
  302                 count = np->n_size - offset;
  303                 if (count < 0)
  304                         count = 0;
  305         }
  306         mtx_unlock(&np->n_mtx);
  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         PCPU_INC(cnt.v_vnodeout);
  317         PCPU_ADD(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                 vnode_pager_undirty_pages(pages, rtvals, count - uio.uio_resid);
  341                 if (must_commit) {
  342                         nfs_clearcommit(vp->v_mount);
  343                 }
  344         }
  345         return rtvals[0];
  346 }
  347 
  348 /*
  349  * For nfs, cache consistency can only be maintained approximately.
  350  * Although RFC1094 does not specify the criteria, the following is
  351  * believed to be compatible with the reference port.
  352  * For nfs:
  353  * If the file's modify time on the server has changed since the
  354  * last read rpc or you have written to the file,
  355  * you may have lost data cache consistency with the
  356  * server, so flush all of the file's data out of the cache.
  357  * Then force a getattr rpc to ensure that you have up to date
  358  * attributes.
  359  * NB: This implies that cache data can be read when up to
  360  * NFS_ATTRTIMEO seconds out of date. If you find that you need current
  361  * attributes this could be forced by setting n_attrstamp to 0 before
  362  * the VOP_GETATTR() call.
  363  */
  364 static inline int
  365 nfs_bioread_check_cons(struct vnode *vp, struct thread *td, struct ucred *cred)
  366 {
  367         int error = 0;
  368         struct vattr vattr;
  369         struct nfsnode *np = VTONFS(vp);
  370         int old_lock;
  371         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  372         
  373         /*
  374          * Grab the exclusive lock before checking whether the cache is
  375          * consistent.
  376          * XXX - We can make this cheaper later (by acquiring cheaper locks).
  377          * But for now, this suffices.
  378          */
  379         old_lock = nfs_upgrade_vnlock(vp);
  380         if (vp->v_iflag & VI_DOOMED) {
  381                 nfs_downgrade_vnlock(vp, old_lock);
  382                 return (EBADF);
  383         }
  384                 
  385         mtx_lock(&np->n_mtx);
  386         if (np->n_flag & NMODIFIED) {
  387                 mtx_unlock(&np->n_mtx);
  388                 if (vp->v_type != VREG) {
  389                         if (vp->v_type != VDIR)
  390                                 panic("nfs: bioread, not dir");
  391                         (nmp->nm_rpcops->nr_invaldir)(vp);
  392                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  393                         if (error)
  394                                 goto out;
  395                 }
  396                 np->n_attrstamp = 0;
  397                 KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  398                 error = VOP_GETATTR(vp, &vattr, cred);
  399                 if (error)
  400                         goto out;
  401                 mtx_lock(&np->n_mtx);
  402                 np->n_mtime = vattr.va_mtime;
  403                 mtx_unlock(&np->n_mtx);
  404         } else {
  405                 mtx_unlock(&np->n_mtx);
  406                 error = VOP_GETATTR(vp, &vattr, cred);
  407                 if (error)
  408                         return (error);
  409                 mtx_lock(&np->n_mtx);
  410                 if ((np->n_flag & NSIZECHANGED)
  411                     || (NFS_TIMESPEC_COMPARE(&np->n_mtime, &vattr.va_mtime))) {
  412                         mtx_unlock(&np->n_mtx);
  413                         if (vp->v_type == VDIR)
  414                                 (nmp->nm_rpcops->nr_invaldir)(vp);
  415                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  416                         if (error)
  417                                 goto out;
  418                         mtx_lock(&np->n_mtx);
  419                         np->n_mtime = vattr.va_mtime;
  420                         np->n_flag &= ~NSIZECHANGED;
  421                 }
  422                 mtx_unlock(&np->n_mtx);
  423         }
  424 out:    
  425         nfs_downgrade_vnlock(vp, old_lock);
  426         return error;
  427 }
  428 
  429 /*
  430  * Vnode op for read using bio
  431  */
  432 int
  433 nfs_bioread(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred)
  434 {
  435         struct nfsnode *np = VTONFS(vp);
  436         int biosize, i;
  437         struct buf *bp, *rabp;
  438         struct thread *td;
  439         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  440         daddr_t lbn, rabn;
  441         off_t end;
  442         int bcount;
  443         int seqcount;
  444         int nra, error = 0, n = 0, on = 0;
  445 
  446         KASSERT(uio->uio_rw == UIO_READ, ("nfs_read mode"));
  447         if (uio->uio_resid == 0)
  448                 return (0);
  449         if (uio->uio_offset < 0)        /* XXX VDIR cookies can be negative */
  450                 return (EINVAL);
  451         td = uio->uio_td;
  452 
  453         mtx_lock(&nmp->nm_mtx);
  454         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  455             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  456                 mtx_unlock(&nmp->nm_mtx);
  457                 (void)nfs_fsinfo(nmp, vp, cred, td);
  458         } else
  459                 mtx_unlock(&nmp->nm_mtx);               
  460 
  461         end = uio->uio_offset + uio->uio_resid;
  462         if (vp->v_type != VDIR &&
  463             (end > nmp->nm_maxfilesize || end < uio->uio_offset))
  464                 return (EFBIG);
  465 
  466         if (nfs_directio_enable && (ioflag & IO_DIRECT) && (vp->v_type == VREG))
  467                 /* No caching/ no readaheads. Just read data into the user buffer */
  468                 return nfs_readrpc(vp, uio, cred);
  469 
  470         biosize = vp->v_bufobj.bo_bsize;
  471         seqcount = (int)((off_t)(ioflag >> IO_SEQSHIFT) * biosize / BKVASIZE);
  472         
  473         error = nfs_bioread_check_cons(vp, td, cred);
  474         if (error)
  475                 return error;
  476 
  477         do {
  478             u_quad_t nsize;
  479                         
  480             mtx_lock(&np->n_mtx);
  481             nsize = np->n_size;
  482             mtx_unlock(&np->n_mtx);                 
  483 
  484             switch (vp->v_type) {
  485             case VREG:
  486                 nfsstats.biocache_reads++;
  487                 lbn = uio->uio_offset / biosize;
  488                 on = uio->uio_offset & (biosize - 1);
  489 
  490                 /*
  491                  * Start the read ahead(s), as required.
  492                  */
  493                 if (nmp->nm_readahead > 0) {
  494                     for (nra = 0; nra < nmp->nm_readahead && nra < seqcount &&
  495                         (off_t)(lbn + 1 + nra) * biosize < nsize; nra++) {
  496                         rabn = lbn + 1 + nra;
  497                         if (incore(&vp->v_bufobj, rabn) == NULL) {
  498                             rabp = nfs_getcacheblk(vp, rabn, biosize, td);
  499                             if (!rabp) {
  500                                 error = nfs_sigintr(nmp, td);
  501                                 return (error ? error : EINTR);
  502                             }
  503                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  504                                 rabp->b_flags |= B_ASYNC;
  505                                 rabp->b_iocmd = BIO_READ;
  506                                 vfs_busy_pages(rabp, 0);
  507                                 if (nfs_asyncio(nmp, rabp, cred, td)) {
  508                                     rabp->b_flags |= B_INVAL;
  509                                     rabp->b_ioflags |= BIO_ERROR;
  510                                     vfs_unbusy_pages(rabp);
  511                                     brelse(rabp);
  512                                     break;
  513                                 }
  514                             } else {
  515                                 brelse(rabp);
  516                             }
  517                         }
  518                     }
  519                 }
  520 
  521                 /* Note that bcount is *not* DEV_BSIZE aligned. */
  522                 bcount = biosize;
  523                 if ((off_t)lbn * biosize >= nsize) {
  524                         bcount = 0;
  525                 } else if ((off_t)(lbn + 1) * biosize > nsize) {
  526                         bcount = nsize - (off_t)lbn * biosize;
  527                 }
  528                 bp = nfs_getcacheblk(vp, lbn, bcount, td);
  529 
  530                 if (!bp) {
  531                         error = nfs_sigintr(nmp, td);
  532                         return (error ? error : EINTR);
  533                 }
  534 
  535                 /*
  536                  * If B_CACHE is not set, we must issue the read.  If this
  537                  * fails, we return an error.
  538                  */
  539 
  540                 if ((bp->b_flags & B_CACHE) == 0) {
  541                     bp->b_iocmd = BIO_READ;
  542                     vfs_busy_pages(bp, 0);
  543                     error = nfs_doio(vp, bp, cred, td);
  544                     if (error) {
  545                         brelse(bp);
  546                         return (error);
  547                     }
  548                 }
  549 
  550                 /*
  551                  * on is the offset into the current bp.  Figure out how many
  552                  * bytes we can copy out of the bp.  Note that bcount is
  553                  * NOT DEV_BSIZE aligned.
  554                  *
  555                  * Then figure out how many bytes we can copy into the uio.
  556                  */
  557 
  558                 n = 0;
  559                 if (on < bcount)
  560                         n = min((unsigned)(bcount - on), uio->uio_resid);
  561                 break;
  562             case VLNK:
  563                 nfsstats.biocache_readlinks++;
  564                 bp = nfs_getcacheblk(vp, (daddr_t)0, NFS_MAXPATHLEN, td);
  565                 if (!bp) {
  566                         error = nfs_sigintr(nmp, td);
  567                         return (error ? error : EINTR);
  568                 }
  569                 if ((bp->b_flags & B_CACHE) == 0) {
  570                     bp->b_iocmd = BIO_READ;
  571                     vfs_busy_pages(bp, 0);
  572                     error = nfs_doio(vp, bp, cred, td);
  573                     if (error) {
  574                         bp->b_ioflags |= BIO_ERROR;
  575                         brelse(bp);
  576                         return (error);
  577                     }
  578                 }
  579                 n = min(uio->uio_resid, NFS_MAXPATHLEN - bp->b_resid);
  580                 on = 0;
  581                 break;
  582             case VDIR:
  583                 nfsstats.biocache_readdirs++;
  584                 if (np->n_direofoffset
  585                     && uio->uio_offset >= np->n_direofoffset) {
  586                     return (0);
  587                 }
  588                 lbn = (uoff_t)uio->uio_offset / NFS_DIRBLKSIZ;
  589                 on = uio->uio_offset & (NFS_DIRBLKSIZ - 1);
  590                 bp = nfs_getcacheblk(vp, lbn, NFS_DIRBLKSIZ, td);
  591                 if (!bp) {
  592                     error = nfs_sigintr(nmp, td);
  593                     return (error ? error : EINTR);
  594                 }
  595                 if ((bp->b_flags & B_CACHE) == 0) {
  596                     bp->b_iocmd = BIO_READ;
  597                     vfs_busy_pages(bp, 0);
  598                     error = nfs_doio(vp, bp, cred, td);
  599                     if (error) {
  600                             brelse(bp);
  601                     }
  602                     while (error == NFSERR_BAD_COOKIE) {
  603                         (nmp->nm_rpcops->nr_invaldir)(vp);
  604                         error = nfs_vinvalbuf(vp, 0, td, 1);
  605                         /*
  606                          * Yuck! The directory has been modified on the
  607                          * server. The only way to get the block is by
  608                          * reading from the beginning to get all the
  609                          * offset cookies.
  610                          *
  611                          * Leave the last bp intact unless there is an error.
  612                          * Loop back up to the while if the error is another
  613                          * NFSERR_BAD_COOKIE (double yuch!).
  614                          */
  615                         for (i = 0; i <= lbn && !error; i++) {
  616                             if (np->n_direofoffset
  617                                 && (i * NFS_DIRBLKSIZ) >= np->n_direofoffset)
  618                                     return (0);
  619                             bp = nfs_getcacheblk(vp, i, NFS_DIRBLKSIZ, td);
  620                             if (!bp) {
  621                                 error = nfs_sigintr(nmp, td);
  622                                 return (error ? error : EINTR);
  623                             }
  624                             if ((bp->b_flags & B_CACHE) == 0) {
  625                                     bp->b_iocmd = BIO_READ;
  626                                     vfs_busy_pages(bp, 0);
  627                                     error = nfs_doio(vp, bp, cred, td);
  628                                     /*
  629                                      * no error + B_INVAL == directory EOF,
  630                                      * use the block.
  631                                      */
  632                                     if (error == 0 && (bp->b_flags & B_INVAL))
  633                                             break;
  634                             }
  635                             /*
  636                              * An error will throw away the block and the
  637                              * for loop will break out.  If no error and this
  638                              * is not the block we want, we throw away the
  639                              * block and go for the next one via the for loop.
  640                              */
  641                             if (error || i < lbn)
  642                                     brelse(bp);
  643                         }
  644                     }
  645                     /*
  646                      * The above while is repeated if we hit another cookie
  647                      * error.  If we hit an error and it wasn't a cookie error,
  648                      * we give up.
  649                      */
  650                     if (error)
  651                             return (error);
  652                 }
  653 
  654                 /*
  655                  * If not eof and read aheads are enabled, start one.
  656                  * (You need the current block first, so that you have the
  657                  *  directory offset cookie of the next block.)
  658                  */
  659                 if (nmp->nm_readahead > 0 &&
  660                     (bp->b_flags & B_INVAL) == 0 &&
  661                     (np->n_direofoffset == 0 ||
  662                     (lbn + 1) * NFS_DIRBLKSIZ < np->n_direofoffset) &&
  663                     incore(&vp->v_bufobj, lbn + 1) == NULL) {
  664                         rabp = nfs_getcacheblk(vp, lbn + 1, NFS_DIRBLKSIZ, td);
  665                         if (rabp) {
  666                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  667                                 rabp->b_flags |= B_ASYNC;
  668                                 rabp->b_iocmd = BIO_READ;
  669                                 vfs_busy_pages(rabp, 0);
  670                                 if (nfs_asyncio(nmp, rabp, cred, td)) {
  671                                     rabp->b_flags |= B_INVAL;
  672                                     rabp->b_ioflags |= BIO_ERROR;
  673                                     vfs_unbusy_pages(rabp);
  674                                     brelse(rabp);
  675                                 }
  676                             } else {
  677                                 brelse(rabp);
  678                             }
  679                         }
  680                 }
  681                 /*
  682                  * Unlike VREG files, whos buffer size ( bp->b_bcount ) is
  683                  * chopped for the EOF condition, we cannot tell how large
  684                  * NFS directories are going to be until we hit EOF.  So
  685                  * an NFS directory buffer is *not* chopped to its EOF.  Now,
  686                  * it just so happens that b_resid will effectively chop it
  687                  * to EOF.  *BUT* this information is lost if the buffer goes
  688                  * away and is reconstituted into a B_CACHE state ( due to
  689                  * being VMIO ) later.  So we keep track of the directory eof
  690                  * in np->n_direofoffset and chop it off as an extra step
  691                  * right here.
  692                  */
  693                 n = lmin(uio->uio_resid, NFS_DIRBLKSIZ - bp->b_resid - on);
  694                 if (np->n_direofoffset && n > np->n_direofoffset - uio->uio_offset)
  695                         n = np->n_direofoffset - uio->uio_offset;
  696                 break;
  697             default:
  698                 nfs_printf(" nfs_bioread: type %x unexpected\n", vp->v_type);
  699                 bp = NULL;
  700                 break;
  701             };
  702 
  703             if (n > 0) {
  704                     error = uiomove(bp->b_data + on, (int)n, uio);
  705             }
  706             if (vp->v_type == VLNK)
  707                 n = 0;
  708             if (bp != NULL)
  709                 brelse(bp);
  710         } while (error == 0 && uio->uio_resid > 0 && n > 0);
  711         return (error);
  712 }
  713 
  714 /*
  715  * The NFS write path cannot handle iovecs with len > 1. So we need to 
  716  * break up iovecs accordingly (restricting them to wsize).
  717  * For the SYNC case, we can do this with 1 copy (user buffer -> mbuf). 
  718  * For the ASYNC case, 2 copies are needed. The first a copy from the 
  719  * user buffer to a staging buffer and then a second copy from the staging
  720  * buffer to mbufs. This can be optimized by copying from the user buffer
  721  * directly into mbufs and passing the chain down, but that requires a 
  722  * fair amount of re-working of the relevant codepaths (and can be done
  723  * later).
  724  */
  725 static int
  726 nfs_directio_write(vp, uiop, cred, ioflag)
  727         struct vnode *vp;
  728         struct uio *uiop;
  729         struct ucred *cred;
  730         int ioflag;
  731 {
  732         int error;
  733         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  734         struct thread *td = uiop->uio_td;
  735         int size;
  736         int wsize;
  737         
  738         mtx_lock(&nmp->nm_mtx);
  739         wsize = nmp->nm_wsize;
  740         mtx_unlock(&nmp->nm_mtx);
  741         if (ioflag & IO_SYNC) {
  742                 int iomode, must_commit;
  743                 struct uio uio;
  744                 struct iovec iov;
  745 do_sync:
  746                 while (uiop->uio_resid > 0) {
  747                         size = min(uiop->uio_resid, wsize);
  748                         size = min(uiop->uio_iov->iov_len, size);
  749                         iov.iov_base = uiop->uio_iov->iov_base;
  750                         iov.iov_len = size;
  751                         uio.uio_iov = &iov;
  752                         uio.uio_iovcnt = 1;
  753                         uio.uio_offset = uiop->uio_offset;
  754                         uio.uio_resid = size;
  755                         uio.uio_segflg = UIO_USERSPACE;
  756                         uio.uio_rw = UIO_WRITE;
  757                         uio.uio_td = td;
  758                         iomode = NFSV3WRITE_FILESYNC;
  759                         error = (nmp->nm_rpcops->nr_writerpc)(vp, &uio, cred, 
  760                                                       &iomode, &must_commit);
  761                         KASSERT((must_commit == 0), 
  762                                 ("nfs_directio_write: Did not commit write"));
  763                         if (error)
  764                                 return (error);
  765                         uiop->uio_offset += size;
  766                         uiop->uio_resid -= size;
  767                         if (uiop->uio_iov->iov_len <= size) {
  768                                 uiop->uio_iovcnt--;
  769                                 uiop->uio_iov++;
  770                         } else {
  771                                 uiop->uio_iov->iov_base = 
  772                                         (char *)uiop->uio_iov->iov_base + size;
  773                                 uiop->uio_iov->iov_len -= size;
  774                         }
  775                 }
  776         } else {
  777                 struct uio *t_uio;
  778                 struct iovec *t_iov;
  779                 struct buf *bp;
  780                 
  781                 /*
  782                  * Break up the write into blocksize chunks and hand these
  783                  * over to nfsiod's for write back.
  784                  * Unfortunately, this incurs a copy of the data. Since 
  785                  * the user could modify the buffer before the write is 
  786                  * initiated.
  787                  * 
  788                  * The obvious optimization here is that one of the 2 copies
  789                  * in the async write path can be eliminated by copying the
  790                  * data here directly into mbufs and passing the mbuf chain
  791                  * down. But that will require a fair amount of re-working
  792                  * of the code and can be done if there's enough interest
  793                  * in NFS directio access.
  794                  */
  795                 while (uiop->uio_resid > 0) {
  796                         size = min(uiop->uio_resid, wsize);
  797                         size = min(uiop->uio_iov->iov_len, size);
  798                         bp = getpbuf(&nfs_pbuf_freecnt);
  799                         t_uio = malloc(sizeof(struct uio), M_NFSDIRECTIO, M_WAITOK);
  800                         t_iov = malloc(sizeof(struct iovec), M_NFSDIRECTIO, M_WAITOK);
  801                         t_iov->iov_base = malloc(size, M_NFSDIRECTIO, M_WAITOK);
  802                         t_iov->iov_len = size;
  803                         t_uio->uio_iov = t_iov;
  804                         t_uio->uio_iovcnt = 1;
  805                         t_uio->uio_offset = uiop->uio_offset;
  806                         t_uio->uio_resid = size;
  807                         t_uio->uio_segflg = UIO_SYSSPACE;
  808                         t_uio->uio_rw = UIO_WRITE;
  809                         t_uio->uio_td = td;
  810                         bcopy(uiop->uio_iov->iov_base, t_iov->iov_base, size);
  811                         bp->b_flags |= B_DIRECT;
  812                         bp->b_iocmd = BIO_WRITE;
  813                         if (cred != NOCRED) {
  814                                 crhold(cred);
  815                                 bp->b_wcred = cred;
  816                         } else 
  817                                 bp->b_wcred = NOCRED;                   
  818                         bp->b_caller1 = (void *)t_uio;
  819                         bp->b_vp = vp;
  820                         error = nfs_asyncio(nmp, bp, NOCRED, td);
  821                         if (error) {
  822                                 free(t_iov->iov_base, M_NFSDIRECTIO);
  823                                 free(t_iov, M_NFSDIRECTIO);
  824                                 free(t_uio, M_NFSDIRECTIO);
  825                                 bp->b_vp = NULL;
  826                                 relpbuf(bp, &nfs_pbuf_freecnt);
  827                                 if (error == EINTR)
  828                                         return (error);
  829                                 goto do_sync;
  830                         }
  831                         uiop->uio_offset += size;
  832                         uiop->uio_resid -= size;
  833                         if (uiop->uio_iov->iov_len <= size) {
  834                                 uiop->uio_iovcnt--;
  835                                 uiop->uio_iov++;
  836                         } else {
  837                                 uiop->uio_iov->iov_base = 
  838                                         (char *)uiop->uio_iov->iov_base + size;
  839                                 uiop->uio_iov->iov_len -= size;
  840                         }
  841                 }
  842         }
  843         return (0);
  844 }
  845 
  846 /*
  847  * Vnode op for write using bio
  848  */
  849 int
  850 nfs_write(struct vop_write_args *ap)
  851 {
  852         int biosize;
  853         struct uio *uio = ap->a_uio;
  854         struct thread *td = uio->uio_td;
  855         struct vnode *vp = ap->a_vp;
  856         struct nfsnode *np = VTONFS(vp);
  857         struct ucred *cred = ap->a_cred;
  858         int ioflag = ap->a_ioflag;
  859         struct buf *bp;
  860         struct vattr vattr;
  861         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  862         daddr_t lbn;
  863         off_t end;
  864         int bcount;
  865         int n, on, error = 0;
  866 
  867         KASSERT(uio->uio_rw == UIO_WRITE, ("nfs_write mode"));
  868         KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
  869             ("nfs_write proc"));
  870         if (vp->v_type != VREG)
  871                 return (EIO);
  872         mtx_lock(&np->n_mtx);
  873         if (np->n_flag & NWRITEERR) {
  874                 np->n_flag &= ~NWRITEERR;
  875                 mtx_unlock(&np->n_mtx);
  876                 return (np->n_error);
  877         } else
  878                 mtx_unlock(&np->n_mtx);
  879         mtx_lock(&nmp->nm_mtx);
  880         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  881             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  882                 mtx_unlock(&nmp->nm_mtx);
  883                 (void)nfs_fsinfo(nmp, vp, cred, td);
  884         } else
  885                 mtx_unlock(&nmp->nm_mtx);
  886 
  887         /*
  888          * Synchronously flush pending buffers if we are in synchronous
  889          * mode or if we are appending.
  890          */
  891         if (ioflag & (IO_APPEND | IO_SYNC)) {
  892                 mtx_lock(&np->n_mtx);
  893                 if (np->n_flag & NMODIFIED) {
  894                         mtx_unlock(&np->n_mtx);
  895 #ifdef notyet /* Needs matching nonblock semantics elsewhere, too. */
  896                         /*
  897                          * Require non-blocking, synchronous writes to
  898                          * dirty files to inform the program it needs
  899                          * to fsync(2) explicitly.
  900                          */
  901                         if (ioflag & IO_NDELAY)
  902                                 return (EAGAIN);
  903 #endif
  904 flush_and_restart:
  905                         np->n_attrstamp = 0;
  906                         KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  907                         error = nfs_vinvalbuf(vp, V_SAVE, td, 1);
  908                         if (error)
  909                                 return (error);
  910                 } else
  911                         mtx_unlock(&np->n_mtx);
  912         }
  913 
  914         /*
  915          * If IO_APPEND then load uio_offset.  We restart here if we cannot
  916          * get the append lock.
  917          */
  918         if (ioflag & IO_APPEND) {
  919                 np->n_attrstamp = 0;
  920                 KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  921                 error = VOP_GETATTR(vp, &vattr, cred);
  922                 if (error)
  923                         return (error);
  924                 mtx_lock(&np->n_mtx);
  925                 uio->uio_offset = np->n_size;
  926                 mtx_unlock(&np->n_mtx);
  927         }
  928 
  929         if (uio->uio_offset < 0)
  930                 return (EINVAL);
  931         end = uio->uio_offset + uio->uio_resid;
  932         if (end > nmp->nm_maxfilesize || end < uio->uio_offset)
  933                 return (EFBIG);
  934         if (uio->uio_resid == 0)
  935                 return (0);
  936 
  937         if (nfs_directio_enable && (ioflag & IO_DIRECT) && vp->v_type == VREG)
  938                 return nfs_directio_write(vp, uio, cred, ioflag);
  939 
  940         /*
  941          * Maybe this should be above the vnode op call, but so long as
  942          * file servers have no limits, i don't think it matters
  943          */
  944         if (vn_rlimit_fsize(vp, uio, td))
  945                 return (EFBIG);
  946 
  947         biosize = vp->v_bufobj.bo_bsize;
  948         /*
  949          * Find all of this file's B_NEEDCOMMIT buffers.  If our writes
  950          * would exceed the local maximum per-file write commit size when
  951          * combined with those, we must decide whether to flush,
  952          * go synchronous, or return error.  We don't bother checking
  953          * IO_UNIT -- we just make all writes atomic anyway, as there's
  954          * no point optimizing for something that really won't ever happen.
  955          */
  956         if (!(ioflag & IO_SYNC)) {
  957                 int nflag;
  958 
  959                 mtx_lock(&np->n_mtx);
  960                 nflag = np->n_flag;
  961                 mtx_unlock(&np->n_mtx);         
  962                 int needrestart = 0;
  963                 if (nmp->nm_wcommitsize < uio->uio_resid) {
  964                         /*
  965                          * If this request could not possibly be completed
  966                          * without exceeding the maximum outstanding write
  967                          * commit size, see if we can convert it into a
  968                          * synchronous write operation.
  969                          */
  970                         if (ioflag & IO_NDELAY)
  971                                 return (EAGAIN);
  972                         ioflag |= IO_SYNC;
  973                         if (nflag & NMODIFIED)
  974                                 needrestart = 1;
  975                 } else if (nflag & NMODIFIED) {
  976                         int wouldcommit = 0;
  977                         BO_LOCK(&vp->v_bufobj);
  978                         if (vp->v_bufobj.bo_dirty.bv_cnt != 0) {
  979                                 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd,
  980                                     b_bobufs) {
  981                                         if (bp->b_flags & B_NEEDCOMMIT)
  982                                                 wouldcommit += bp->b_bcount;
  983                                 }
  984                         }
  985                         BO_UNLOCK(&vp->v_bufobj);
  986                         /*
  987                          * Since we're not operating synchronously and
  988                          * bypassing the buffer cache, we are in a commit
  989                          * and holding all of these buffers whether
  990                          * transmitted or not.  If not limited, this
  991                          * will lead to the buffer cache deadlocking,
  992                          * as no one else can flush our uncommitted buffers.
  993                          */
  994                         wouldcommit += uio->uio_resid;
  995                         /*
  996                          * If we would initially exceed the maximum
  997                          * outstanding write commit size, flush and restart.
  998                          */
  999                         if (wouldcommit > nmp->nm_wcommitsize)
 1000                                 needrestart = 1;
 1001                 }
 1002                 if (needrestart)
 1003                         goto flush_and_restart;
 1004         }
 1005 
 1006         do {
 1007                 nfsstats.biocache_writes++;
 1008                 lbn = uio->uio_offset / biosize;
 1009                 on = uio->uio_offset & (biosize-1);
 1010                 n = min((unsigned)(biosize - on), uio->uio_resid);
 1011 again:
 1012                 /*
 1013                  * Handle direct append and file extension cases, calculate
 1014                  * unaligned buffer size.
 1015                  */
 1016                 mtx_lock(&np->n_mtx);
 1017                 if (uio->uio_offset == np->n_size && n) {
 1018                         mtx_unlock(&np->n_mtx);
 1019                         /*
 1020                          * Get the buffer (in its pre-append state to maintain
 1021                          * B_CACHE if it was previously set).  Resize the
 1022                          * nfsnode after we have locked the buffer to prevent
 1023                          * readers from reading garbage.
 1024                          */
 1025                         bcount = on;
 1026                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1027 
 1028                         if (bp != NULL) {
 1029                                 long save;
 1030 
 1031                                 mtx_lock(&np->n_mtx);
 1032                                 np->n_size = uio->uio_offset + n;
 1033                                 np->n_flag |= NMODIFIED;
 1034                                 vnode_pager_setsize(vp, np->n_size);
 1035                                 mtx_unlock(&np->n_mtx);
 1036 
 1037                                 save = bp->b_flags & B_CACHE;
 1038                                 bcount += n;
 1039                                 allocbuf(bp, bcount);
 1040                                 bp->b_flags |= save;
 1041                         }
 1042                 } else {
 1043                         /*
 1044                          * Obtain the locked cache block first, and then
 1045                          * adjust the file's size as appropriate.
 1046                          */
 1047                         bcount = on + n;
 1048                         if ((off_t)lbn * biosize + bcount < np->n_size) {
 1049                                 if ((off_t)(lbn + 1) * biosize < np->n_size)
 1050                                         bcount = biosize;
 1051                                 else
 1052                                         bcount = np->n_size - (off_t)lbn * biosize;
 1053                         }
 1054                         mtx_unlock(&np->n_mtx);
 1055                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1056                         mtx_lock(&np->n_mtx);
 1057                         if (uio->uio_offset + n > np->n_size) {
 1058                                 np->n_size = uio->uio_offset + n;
 1059                                 np->n_flag |= NMODIFIED;
 1060                                 vnode_pager_setsize(vp, np->n_size);
 1061                         }
 1062                         mtx_unlock(&np->n_mtx);
 1063                 }
 1064 
 1065                 if (!bp) {
 1066                         error = nfs_sigintr(nmp, td);
 1067                         if (!error)
 1068                                 error = EINTR;
 1069                         break;
 1070                 }
 1071 
 1072                 /*
 1073                  * Issue a READ if B_CACHE is not set.  In special-append
 1074                  * mode, B_CACHE is based on the buffer prior to the write
 1075                  * op and is typically set, avoiding the read.  If a read
 1076                  * is required in special append mode, the server will
 1077                  * probably send us a short-read since we extended the file
 1078                  * on our end, resulting in b_resid == 0 and, thusly,
 1079                  * B_CACHE getting set.
 1080                  *
 1081                  * We can also avoid issuing the read if the write covers
 1082                  * the entire buffer.  We have to make sure the buffer state
 1083                  * is reasonable in this case since we will not be initiating
 1084                  * I/O.  See the comments in kern/vfs_bio.c's getblk() for
 1085                  * more information.
 1086                  *
 1087                  * B_CACHE may also be set due to the buffer being cached
 1088                  * normally.
 1089                  */
 1090 
 1091                 if (on == 0 && n == bcount) {
 1092                         bp->b_flags |= B_CACHE;
 1093                         bp->b_flags &= ~B_INVAL;
 1094                         bp->b_ioflags &= ~BIO_ERROR;
 1095                 }
 1096 
 1097                 if ((bp->b_flags & B_CACHE) == 0) {
 1098                         bp->b_iocmd = BIO_READ;
 1099                         vfs_busy_pages(bp, 0);
 1100                         error = nfs_doio(vp, bp, cred, td);
 1101                         if (error) {
 1102                                 brelse(bp);
 1103                                 break;
 1104                         }
 1105                 }
 1106                 if (bp->b_wcred == NOCRED)
 1107                         bp->b_wcred = crhold(cred);
 1108                 mtx_lock(&np->n_mtx);
 1109                 np->n_flag |= NMODIFIED;
 1110                 mtx_unlock(&np->n_mtx);
 1111 
 1112                 /*
 1113                  * If dirtyend exceeds file size, chop it down.  This should
 1114                  * not normally occur but there is an append race where it
 1115                  * might occur XXX, so we log it.
 1116                  *
 1117                  * If the chopping creates a reverse-indexed or degenerate
 1118                  * situation with dirtyoff/end, we 0 both of them.
 1119                  */
 1120 
 1121                 if (bp->b_dirtyend > bcount) {
 1122                         nfs_printf("NFS append race @%lx:%d\n",
 1123                             (long)bp->b_blkno * DEV_BSIZE,
 1124                             bp->b_dirtyend - bcount);
 1125                         bp->b_dirtyend = bcount;
 1126                 }
 1127 
 1128                 if (bp->b_dirtyoff >= bp->b_dirtyend)
 1129                         bp->b_dirtyoff = bp->b_dirtyend = 0;
 1130 
 1131                 /*
 1132                  * If the new write will leave a contiguous dirty
 1133                  * area, just update the b_dirtyoff and b_dirtyend,
 1134                  * otherwise force a write rpc of the old dirty area.
 1135                  *
 1136                  * While it is possible to merge discontiguous writes due to
 1137                  * our having a B_CACHE buffer ( and thus valid read data
 1138                  * for the hole), we don't because it could lead to
 1139                  * significant cache coherency problems with multiple clients,
 1140                  * especially if locking is implemented later on.
 1141                  *
 1142                  * as an optimization we could theoretically maintain
 1143                  * a linked list of discontinuous areas, but we would still
 1144                  * have to commit them separately so there isn't much
 1145                  * advantage to it except perhaps a bit of asynchronization.
 1146                  */
 1147 
 1148                 if (bp->b_dirtyend > 0 &&
 1149                     (on > bp->b_dirtyend || (on + n) < bp->b_dirtyoff)) {
 1150                         if (bwrite(bp) == EINTR) {
 1151                                 error = EINTR;
 1152                                 break;
 1153                         }
 1154                         goto again;
 1155                 }
 1156 
 1157                 error = uiomove((char *)bp->b_data + on, n, uio);
 1158 
 1159                 /*
 1160                  * Since this block is being modified, it must be written
 1161                  * again and not just committed.  Since write clustering does
 1162                  * not work for the stage 1 data write, only the stage 2
 1163                  * commit rpc, we have to clear B_CLUSTEROK as well.
 1164                  */
 1165                 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1166 
 1167                 if (error) {
 1168                         bp->b_ioflags |= BIO_ERROR;
 1169                         brelse(bp);
 1170                         break;
 1171                 }
 1172 
 1173                 /*
 1174                  * Only update dirtyoff/dirtyend if not a degenerate
 1175                  * condition.
 1176                  */
 1177                 if (n) {
 1178                         if (bp->b_dirtyend > 0) {
 1179                                 bp->b_dirtyoff = min(on, bp->b_dirtyoff);
 1180                                 bp->b_dirtyend = max((on + n), bp->b_dirtyend);
 1181                         } else {
 1182                                 bp->b_dirtyoff = on;
 1183                                 bp->b_dirtyend = on + n;
 1184                         }
 1185                         vfs_bio_set_valid(bp, on, n);
 1186                 }
 1187 
 1188                 /*
 1189                  * If IO_SYNC do bwrite().
 1190                  *
 1191                  * IO_INVAL appears to be unused.  The idea appears to be
 1192                  * to turn off caching in this case.  Very odd.  XXX
 1193                  */
 1194                 if ((ioflag & IO_SYNC)) {
 1195                         if (ioflag & IO_INVAL)
 1196                                 bp->b_flags |= B_NOCACHE;
 1197                         error = bwrite(bp);
 1198                         if (error)
 1199                                 break;
 1200                 } else if ((n + on) == biosize) {
 1201                         bp->b_flags |= B_ASYNC;
 1202                         (void) (nmp->nm_rpcops->nr_writebp)(bp, 0, NULL);
 1203                 } else {
 1204                         bdwrite(bp);
 1205                 }
 1206         } while (uio->uio_resid > 0 && n > 0);
 1207 
 1208         return (error);
 1209 }
 1210 
 1211 /*
 1212  * Get an nfs cache block.
 1213  *
 1214  * Allocate a new one if the block isn't currently in the cache
 1215  * and return the block marked busy. If the calling process is
 1216  * interrupted by a signal for an interruptible mount point, return
 1217  * NULL.
 1218  *
 1219  * The caller must carefully deal with the possible B_INVAL state of
 1220  * the buffer.  nfs_doio() clears B_INVAL (and nfs_asyncio() clears it
 1221  * indirectly), so synchronous reads can be issued without worrying about
 1222  * the B_INVAL state.  We have to be a little more careful when dealing
 1223  * with writes (see comments in nfs_write()) when extending a file past
 1224  * its EOF.
 1225  */
 1226 static struct buf *
 1227 nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size, struct thread *td)
 1228 {
 1229         struct buf *bp;
 1230         struct mount *mp;
 1231         struct nfsmount *nmp;
 1232 
 1233         mp = vp->v_mount;
 1234         nmp = VFSTONFS(mp);
 1235 
 1236         if (nmp->nm_flag & NFSMNT_INT) {
 1237                 sigset_t oldset;
 1238 
 1239                 nfs_set_sigmask(td, &oldset);
 1240                 bp = getblk(vp, bn, size, NFS_PCATCH, 0, 0);
 1241                 nfs_restore_sigmask(td, &oldset);
 1242                 while (bp == NULL) {
 1243                         if (nfs_sigintr(nmp, td))
 1244                                 return (NULL);
 1245                         bp = getblk(vp, bn, size, 0, 2 * hz, 0);
 1246                 }
 1247         } else {
 1248                 bp = getblk(vp, bn, size, 0, 0, 0);
 1249         }
 1250 
 1251         if (vp->v_type == VREG)
 1252                 bp->b_blkno = bn * (vp->v_bufobj.bo_bsize / DEV_BSIZE);
 1253         return (bp);
 1254 }
 1255 
 1256 /*
 1257  * Flush and invalidate all dirty buffers. If another process is already
 1258  * doing the flush, just wait for completion.
 1259  */
 1260 int
 1261 nfs_vinvalbuf(struct vnode *vp, int flags, struct thread *td, int intrflg)
 1262 {
 1263         struct nfsnode *np = VTONFS(vp);
 1264         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
 1265         int error = 0, slpflag, slptimeo;
 1266         int old_lock = 0;
 1267 
 1268         ASSERT_VOP_LOCKED(vp, "nfs_vinvalbuf");
 1269 
 1270         if ((nmp->nm_flag & NFSMNT_INT) == 0)
 1271                 intrflg = 0;
 1272         if (intrflg) {
 1273                 slpflag = NFS_PCATCH;
 1274                 slptimeo = 2 * hz;
 1275         } else {
 1276                 slpflag = 0;
 1277                 slptimeo = 0;
 1278         }
 1279 
 1280         old_lock = nfs_upgrade_vnlock(vp);
 1281         if (vp->v_iflag & VI_DOOMED) {
 1282                 /*
 1283                  * Since vgonel() uses the generic vinvalbuf() to flush
 1284                  * dirty buffers and it does not call this function, it
 1285                  * is safe to just return OK when VI_DOOMED is set.
 1286                  */
 1287                 nfs_downgrade_vnlock(vp, old_lock);
 1288                 return (0);
 1289         }
 1290 
 1291         /*
 1292          * Now, flush as required.
 1293          */
 1294         if ((flags & V_SAVE) && (vp->v_bufobj.bo_object != NULL)) {
 1295                 VM_OBJECT_LOCK(vp->v_bufobj.bo_object);
 1296                 vm_object_page_clean(vp->v_bufobj.bo_object, 0, 0, OBJPC_SYNC);
 1297                 VM_OBJECT_UNLOCK(vp->v_bufobj.bo_object);
 1298                 /*
 1299                  * If the page clean was interrupted, fail the invalidation.
 1300                  * Not doing so, we run the risk of losing dirty pages in the 
 1301                  * vinvalbuf() call below.
 1302                  */
 1303                 if (intrflg && (error = nfs_sigintr(nmp, td)))
 1304                         goto out;
 1305         }
 1306 
 1307         error = vinvalbuf(vp, flags, slpflag, 0);
 1308         while (error) {
 1309                 if (intrflg && (error = nfs_sigintr(nmp, td)))
 1310                         goto out;
 1311                 error = vinvalbuf(vp, flags, 0, slptimeo);
 1312         }
 1313         mtx_lock(&np->n_mtx);
 1314         if (np->n_directio_asyncwr == 0)
 1315                 np->n_flag &= ~NMODIFIED;
 1316         mtx_unlock(&np->n_mtx);
 1317 out:
 1318         nfs_downgrade_vnlock(vp, old_lock);
 1319         return error;
 1320 }
 1321 
 1322 /*
 1323  * Initiate asynchronous I/O. Return an error if no nfsiods are available.
 1324  * This is mainly to avoid queueing async I/O requests when the nfsiods
 1325  * are all hung on a dead server.
 1326  *
 1327  * Note: nfs_asyncio() does not clear (BIO_ERROR|B_INVAL) but when the bp
 1328  * is eventually dequeued by the async daemon, nfs_doio() *will*.
 1329  */
 1330 int
 1331 nfs_asyncio(struct nfsmount *nmp, struct buf *bp, struct ucred *cred, struct thread *td)
 1332 {
 1333         int iod;
 1334         int gotiod;
 1335         int slpflag = 0;
 1336         int slptimeo = 0;
 1337         int error, error2;
 1338 
 1339         /*
 1340          * Commits are usually short and sweet so lets save some cpu and
 1341          * leave the async daemons for more important rpc's (such as reads
 1342          * and writes).
 1343          */
 1344         mtx_lock(&nfs_iod_mtx);
 1345         if (bp->b_iocmd == BIO_WRITE && (bp->b_flags & B_NEEDCOMMIT) &&
 1346             (nmp->nm_bufqiods > nfs_numasync / 2)) {
 1347                 mtx_unlock(&nfs_iod_mtx);
 1348                 return(EIO);
 1349         }
 1350 again:
 1351         if (nmp->nm_flag & NFSMNT_INT)
 1352                 slpflag = NFS_PCATCH;
 1353         gotiod = FALSE;
 1354 
 1355         /*
 1356          * Find a free iod to process this request.
 1357          */
 1358         for (iod = 0; iod < nfs_numasync; iod++)
 1359                 if (nfs_iodwant[iod] == NFSIOD_AVAILABLE) {
 1360                         gotiod = TRUE;
 1361                         break;
 1362                 }
 1363 
 1364         /*
 1365          * Try to create one if none are free.
 1366          */
 1367         if (!gotiod)
 1368                 nfs_nfsiodnew();
 1369         else {
 1370                 /*
 1371                  * Found one, so wake it up and tell it which
 1372                  * mount to process.
 1373                  */
 1374                 NFS_DPF(ASYNCIO, ("nfs_asyncio: waking iod %d for mount %p\n",
 1375                     iod, nmp));
 1376                 nfs_iodwant[iod] = NFSIOD_NOT_AVAILABLE;
 1377                 nfs_iodmount[iod] = nmp;
 1378                 nmp->nm_bufqiods++;
 1379                 wakeup(&nfs_iodwant[iod]);
 1380         }
 1381 
 1382         /*
 1383          * If none are free, we may already have an iod working on this mount
 1384          * point.  If so, it will process our request.
 1385          */
 1386         if (!gotiod) {
 1387                 if (nmp->nm_bufqiods > 0) {
 1388                         NFS_DPF(ASYNCIO,
 1389                 ("nfs_asyncio: %d iods are already processing mount %p\n",
 1390                                  nmp->nm_bufqiods, nmp));
 1391                         gotiod = TRUE;
 1392                 }
 1393         }
 1394 
 1395         /*
 1396          * If we have an iod which can process the request, then queue
 1397          * the buffer.
 1398          */
 1399         if (gotiod) {
 1400                 /*
 1401                  * Ensure that the queue never grows too large.  We still want
 1402                  * to asynchronize so we block rather then return EIO.
 1403                  */
 1404                 while (nmp->nm_bufqlen >= 2 * nfs_numasync) {
 1405                         NFS_DPF(ASYNCIO,
 1406                 ("nfs_asyncio: waiting for mount %p queue to drain\n", nmp));
 1407                         nmp->nm_bufqwant = TRUE;
 1408                         error = nfs_msleep(td, &nmp->nm_bufq, &nfs_iod_mtx, 
 1409                                            slpflag | PRIBIO,
 1410                                            "nfsaio", slptimeo);
 1411                         if (error) {
 1412                                 error2 = nfs_sigintr(nmp, td);
 1413                                 if (error2) {
 1414                                         mtx_unlock(&nfs_iod_mtx);
 1415                                         return (error2);
 1416                                 }
 1417                                 if (slpflag == NFS_PCATCH) {
 1418                                         slpflag = 0;
 1419                                         slptimeo = 2 * hz;
 1420                                 }
 1421                         }
 1422                         /*
 1423                          * We might have lost our iod while sleeping,
 1424                          * so check and loop if nescessary.
 1425                          */
 1426                         goto again;
 1427                 }
 1428 
 1429                 /* We might have lost our nfsiod */
 1430                 if (nmp->nm_bufqiods == 0) {
 1431                         NFS_DPF(ASYNCIO,
 1432 ("nfs_asyncio: no iods after mount %p queue was drained, looping\n", nmp));
 1433                         goto again;
 1434                 }
 1435 
 1436                 if (bp->b_iocmd == BIO_READ) {
 1437                         if (bp->b_rcred == NOCRED && cred != NOCRED)
 1438                                 bp->b_rcred = crhold(cred);
 1439                 } else {
 1440                         if (bp->b_wcred == NOCRED && cred != NOCRED)
 1441                                 bp->b_wcred = crhold(cred);
 1442                 }
 1443 
 1444                 if (bp->b_flags & B_REMFREE)
 1445                         bremfreef(bp);
 1446                 BUF_KERNPROC(bp);
 1447                 TAILQ_INSERT_TAIL(&nmp->nm_bufq, bp, b_freelist);
 1448                 nmp->nm_bufqlen++;
 1449                 if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1450                         mtx_lock(&(VTONFS(bp->b_vp))->n_mtx);                   
 1451                         VTONFS(bp->b_vp)->n_flag |= NMODIFIED;
 1452                         VTONFS(bp->b_vp)->n_directio_asyncwr++;
 1453                         mtx_unlock(&(VTONFS(bp->b_vp))->n_mtx);
 1454                 }
 1455                 mtx_unlock(&nfs_iod_mtx);
 1456                 return (0);
 1457         }
 1458 
 1459         mtx_unlock(&nfs_iod_mtx);
 1460 
 1461         /*
 1462          * All the iods are busy on other mounts, so return EIO to
 1463          * force the caller to process the i/o synchronously.
 1464          */
 1465         NFS_DPF(ASYNCIO, ("nfs_asyncio: no iods available, i/o is synchronous\n"));
 1466         return (EIO);
 1467 }
 1468 
 1469 void
 1470 nfs_doio_directwrite(struct buf *bp)
 1471 {
 1472         int iomode, must_commit;
 1473         struct uio *uiop = (struct uio *)bp->b_caller1;
 1474         char *iov_base = uiop->uio_iov->iov_base;
 1475         struct nfsmount *nmp = VFSTONFS(bp->b_vp->v_mount);
 1476         
 1477         iomode = NFSV3WRITE_FILESYNC;
 1478         uiop->uio_td = NULL; /* NULL since we're in nfsiod */
 1479         (nmp->nm_rpcops->nr_writerpc)(bp->b_vp, uiop, bp->b_wcred, &iomode, &must_commit);
 1480         KASSERT((must_commit == 0), ("nfs_doio_directwrite: Did not commit write"));
 1481         free(iov_base, M_NFSDIRECTIO);
 1482         free(uiop->uio_iov, M_NFSDIRECTIO);
 1483         free(uiop, M_NFSDIRECTIO);
 1484         if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1485                 struct nfsnode *np = VTONFS(bp->b_vp);
 1486                 mtx_lock(&np->n_mtx);
 1487                 np->n_directio_asyncwr--;
 1488                 if (np->n_directio_asyncwr == 0) {
 1489                         VTONFS(bp->b_vp)->n_flag &= ~NMODIFIED;
 1490                         if ((np->n_flag & NFSYNCWAIT)) {
 1491                                 np->n_flag &= ~NFSYNCWAIT;
 1492                                 wakeup((caddr_t)&np->n_directio_asyncwr);
 1493                         }
 1494                 }
 1495                 mtx_unlock(&np->n_mtx);
 1496         }
 1497         bp->b_vp = NULL;
 1498         relpbuf(bp, &nfs_pbuf_freecnt);
 1499 }
 1500 
 1501 /*
 1502  * Do an I/O operation to/from a cache block. This may be called
 1503  * synchronously or from an nfsiod.
 1504  */
 1505 int
 1506 nfs_doio(struct vnode *vp, struct buf *bp, struct ucred *cr, struct thread *td)
 1507 {
 1508         struct uio *uiop;
 1509         struct nfsnode *np;
 1510         struct nfsmount *nmp;
 1511         int error = 0, iomode, must_commit = 0;
 1512         struct uio uio;
 1513         struct iovec io;
 1514         struct proc *p = td ? td->td_proc : NULL;
 1515         uint8_t iocmd;
 1516         
 1517         np = VTONFS(vp);
 1518         nmp = VFSTONFS(vp->v_mount);
 1519         uiop = &uio;
 1520         uiop->uio_iov = &io;
 1521         uiop->uio_iovcnt = 1;
 1522         uiop->uio_segflg = UIO_SYSSPACE;
 1523         uiop->uio_td = td;
 1524 
 1525         /*
 1526          * clear BIO_ERROR and B_INVAL state prior to initiating the I/O.  We
 1527          * do this here so we do not have to do it in all the code that
 1528          * calls us.
 1529          */
 1530         bp->b_flags &= ~B_INVAL;
 1531         bp->b_ioflags &= ~BIO_ERROR;
 1532 
 1533         KASSERT(!(bp->b_flags & B_DONE), ("nfs_doio: bp %p already marked done", bp));
 1534         iocmd = bp->b_iocmd;
 1535         if (iocmd == BIO_READ) {
 1536             io.iov_len = uiop->uio_resid = bp->b_bcount;
 1537             io.iov_base = bp->b_data;
 1538             uiop->uio_rw = UIO_READ;
 1539 
 1540             switch (vp->v_type) {
 1541             case VREG:
 1542                 uiop->uio_offset = ((off_t)bp->b_blkno) * DEV_BSIZE;
 1543                 nfsstats.read_bios++;
 1544                 error = (nmp->nm_rpcops->nr_readrpc)(vp, uiop, cr);
 1545 
 1546                 if (!error) {
 1547                     if (uiop->uio_resid) {
 1548                         /*
 1549                          * If we had a short read with no error, we must have
 1550                          * hit a file hole.  We should zero-fill the remainder.
 1551                          * This can also occur if the server hits the file EOF.
 1552                          *
 1553                          * Holes used to be able to occur due to pending
 1554                          * writes, but that is not possible any longer.
 1555                          */
 1556                         int nread = bp->b_bcount - uiop->uio_resid;
 1557                         int left  = uiop->uio_resid;
 1558 
 1559                         if (left > 0)
 1560                                 bzero((char *)bp->b_data + nread, left);
 1561                         uiop->uio_resid = 0;
 1562                     }
 1563                 }
 1564                 /* ASSERT_VOP_LOCKED(vp, "nfs_doio"); */
 1565                 if (p && (vp->v_vflag & VV_TEXT)) {
 1566                         mtx_lock(&np->n_mtx);
 1567                         if (NFS_TIMESPEC_COMPARE(&np->n_mtime, &np->n_vattr.va_mtime)) {
 1568                                 mtx_unlock(&np->n_mtx);
 1569                                 PROC_LOCK(p);
 1570                                 killproc(p, "text file modification");
 1571                                 PROC_UNLOCK(p);
 1572                         } else
 1573                                 mtx_unlock(&np->n_mtx);
 1574                 }
 1575                 break;
 1576             case VLNK:
 1577                 uiop->uio_offset = (off_t)0;
 1578                 nfsstats.readlink_bios++;
 1579                 error = (nmp->nm_rpcops->nr_readlinkrpc)(vp, uiop, cr);
 1580                 break;
 1581             case VDIR:
 1582                 nfsstats.readdir_bios++;
 1583                 uiop->uio_offset = ((u_quad_t)bp->b_lblkno) * NFS_DIRBLKSIZ;
 1584                 if ((nmp->nm_flag & NFSMNT_RDIRPLUS) != 0) {
 1585                         error = nfs_readdirplusrpc(vp, uiop, cr);
 1586                         if (error == NFSERR_NOTSUPP)
 1587                                 nmp->nm_flag &= ~NFSMNT_RDIRPLUS;
 1588                 }
 1589                 if ((nmp->nm_flag & NFSMNT_RDIRPLUS) == 0)
 1590                         error = nfs_readdirrpc(vp, uiop, cr);
 1591                 /*
 1592                  * end-of-directory sets B_INVAL but does not generate an
 1593                  * error.
 1594                  */
 1595                 if (error == 0 && uiop->uio_resid == bp->b_bcount)
 1596                         bp->b_flags |= B_INVAL;
 1597                 break;
 1598             default:
 1599                 nfs_printf("nfs_doio:  type %x unexpected\n", vp->v_type);
 1600                 break;
 1601             };
 1602             if (error) {
 1603                 bp->b_ioflags |= BIO_ERROR;
 1604                 bp->b_error = error;
 1605             }
 1606         } else {
 1607             /*
 1608              * If we only need to commit, try to commit
 1609              */
 1610             if (bp->b_flags & B_NEEDCOMMIT) {
 1611                     int retv;
 1612                     off_t off;
 1613 
 1614                     off = ((u_quad_t)bp->b_blkno) * DEV_BSIZE + bp->b_dirtyoff;
 1615                     retv = (nmp->nm_rpcops->nr_commit)(
 1616                                 vp, off, bp->b_dirtyend-bp->b_dirtyoff,
 1617                                 bp->b_wcred, td);
 1618                     if (retv == 0) {
 1619                             bp->b_dirtyoff = bp->b_dirtyend = 0;
 1620                             bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1621                             bp->b_resid = 0;
 1622                             bufdone(bp);
 1623                             return (0);
 1624                     }
 1625                     if (retv == NFSERR_STALEWRITEVERF) {
 1626                             nfs_clearcommit(vp->v_mount);
 1627                     }
 1628             }
 1629 
 1630             /*
 1631              * Setup for actual write
 1632              */
 1633             mtx_lock(&np->n_mtx);
 1634             if ((off_t)bp->b_blkno * DEV_BSIZE + bp->b_dirtyend > np->n_size)
 1635                 bp->b_dirtyend = np->n_size - (off_t)bp->b_blkno * DEV_BSIZE;
 1636             mtx_unlock(&np->n_mtx);
 1637 
 1638             if (bp->b_dirtyend > bp->b_dirtyoff) {
 1639                 io.iov_len = uiop->uio_resid = bp->b_dirtyend
 1640                     - bp->b_dirtyoff;
 1641                 uiop->uio_offset = (off_t)bp->b_blkno * DEV_BSIZE
 1642                     + bp->b_dirtyoff;
 1643                 io.iov_base = (char *)bp->b_data + bp->b_dirtyoff;
 1644                 uiop->uio_rw = UIO_WRITE;
 1645                 nfsstats.write_bios++;
 1646 
 1647                 if ((bp->b_flags & (B_ASYNC | B_NEEDCOMMIT | B_NOCACHE | B_CLUSTER)) == B_ASYNC)
 1648                     iomode = NFSV3WRITE_UNSTABLE;
 1649                 else
 1650                     iomode = NFSV3WRITE_FILESYNC;
 1651 
 1652                 error = (nmp->nm_rpcops->nr_writerpc)(vp, uiop, cr, &iomode, &must_commit);
 1653 
 1654                 /*
 1655                  * When setting B_NEEDCOMMIT also set B_CLUSTEROK to try
 1656                  * to cluster the buffers needing commit.  This will allow
 1657                  * the system to submit a single commit rpc for the whole
 1658                  * cluster.  We can do this even if the buffer is not 100%
 1659                  * dirty (relative to the NFS blocksize), so we optimize the
 1660                  * append-to-file-case.
 1661                  *
 1662                  * (when clearing B_NEEDCOMMIT, B_CLUSTEROK must also be
 1663                  * cleared because write clustering only works for commit
 1664                  * rpc's, not for the data portion of the write).
 1665                  */
 1666 
 1667                 if (!error && iomode == NFSV3WRITE_UNSTABLE) {
 1668                     bp->b_flags |= B_NEEDCOMMIT;
 1669                     if (bp->b_dirtyoff == 0
 1670                         && bp->b_dirtyend == bp->b_bcount)
 1671                         bp->b_flags |= B_CLUSTEROK;
 1672                 } else {
 1673                     bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1674                 }
 1675 
 1676                 /*
 1677                  * For an interrupted write, the buffer is still valid
 1678                  * and the write hasn't been pushed to the server yet,
 1679                  * so we can't set BIO_ERROR and report the interruption
 1680                  * by setting B_EINTR. For the B_ASYNC case, B_EINTR
 1681                  * is not relevant, so the rpc attempt is essentially
 1682                  * a noop.  For the case of a V3 write rpc not being
 1683                  * committed to stable storage, the block is still
 1684                  * dirty and requires either a commit rpc or another
 1685                  * write rpc with iomode == NFSV3WRITE_FILESYNC before
 1686                  * the block is reused. This is indicated by setting
 1687                  * the B_DELWRI and B_NEEDCOMMIT flags.
 1688                  *
 1689                  * If the buffer is marked B_PAGING, it does not reside on
 1690                  * the vp's paging queues so we cannot call bdirty().  The
 1691                  * bp in this case is not an NFS cache block so we should
 1692                  * be safe. XXX
 1693                  *
 1694                  * The logic below breaks up errors into recoverable and 
 1695                  * unrecoverable. For the former, we clear B_INVAL|B_NOCACHE
 1696                  * and keep the buffer around for potential write retries.
 1697                  * For the latter (eg ESTALE), we toss the buffer away (B_INVAL)
 1698                  * and save the error in the nfsnode. This is less than ideal 
 1699                  * but necessary. Keeping such buffers around could potentially
 1700                  * cause buffer exhaustion eventually (they can never be written
 1701                  * out, so will get constantly be re-dirtied). It also causes
 1702                  * all sorts of vfs panics. For non-recoverable write errors, 
 1703                  * also invalidate the attrcache, so we'll be forced to go over
 1704                  * the wire for this object, returning an error to user on next
 1705                  * call (most of the time).
 1706                  */
 1707                 if (error == EINTR || error == EIO || error == ETIMEDOUT
 1708                     || (!error && (bp->b_flags & B_NEEDCOMMIT))) {
 1709                         int s;
 1710 
 1711                         s = splbio();
 1712                         bp->b_flags &= ~(B_INVAL|B_NOCACHE);
 1713                         if ((bp->b_flags & B_PAGING) == 0) {
 1714                             bdirty(bp);
 1715                             bp->b_flags &= ~B_DONE;
 1716                         }
 1717                         if (error && (bp->b_flags & B_ASYNC) == 0)
 1718                             bp->b_flags |= B_EINTR;
 1719                         splx(s);
 1720                 } else {
 1721                     if (error) {
 1722                         bp->b_ioflags |= BIO_ERROR;
 1723                         bp->b_flags |= B_INVAL;
 1724                         bp->b_error = np->n_error = error;
 1725                         mtx_lock(&np->n_mtx);
 1726                         np->n_flag |= NWRITEERR;
 1727                         np->n_attrstamp = 0;
 1728                         KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
 1729                         mtx_unlock(&np->n_mtx);
 1730                     }
 1731                     bp->b_dirtyoff = bp->b_dirtyend = 0;
 1732                 }
 1733             } else {
 1734                 bp->b_resid = 0;
 1735                 bufdone(bp);
 1736                 return (0);
 1737             }
 1738         }
 1739         bp->b_resid = uiop->uio_resid;
 1740         if (must_commit)
 1741             nfs_clearcommit(vp->v_mount);
 1742         bufdone(bp);
 1743         return (error);
 1744 }
 1745 
 1746 /*
 1747  * Used to aid in handling ftruncate() operations on the NFS client side.
 1748  * Truncation creates a number of special problems for NFS.  We have to
 1749  * throw away VM pages and buffer cache buffers that are beyond EOF, and
 1750  * we have to properly handle VM pages or (potentially dirty) buffers
 1751  * that straddle the truncation point.
 1752  */
 1753 
 1754 int
 1755 nfs_meta_setsize(struct vnode *vp, struct ucred *cred, struct thread *td, u_quad_t nsize)
 1756 {
 1757         struct nfsnode *np = VTONFS(vp);
 1758         u_quad_t tsize;
 1759         int biosize = vp->v_bufobj.bo_bsize;
 1760         int error = 0;
 1761 
 1762         mtx_lock(&np->n_mtx);
 1763         tsize = np->n_size;
 1764         np->n_size = nsize;
 1765         mtx_unlock(&np->n_mtx);
 1766 
 1767         if (nsize < tsize) {
 1768                 struct buf *bp;
 1769                 daddr_t lbn;
 1770                 int bufsize;
 1771 
 1772                 /*
 1773                  * vtruncbuf() doesn't get the buffer overlapping the 
 1774                  * truncation point.  We may have a B_DELWRI and/or B_CACHE
 1775                  * buffer that now needs to be truncated.
 1776                  */
 1777                 error = vtruncbuf(vp, cred, td, nsize, biosize);
 1778                 lbn = nsize / biosize;
 1779                 bufsize = nsize & (biosize - 1);
 1780                 bp = nfs_getcacheblk(vp, lbn, bufsize, td);
 1781                 if (!bp)
 1782                         return EINTR;
 1783                 if (bp->b_dirtyoff > bp->b_bcount)
 1784                         bp->b_dirtyoff = bp->b_bcount;
 1785                 if (bp->b_dirtyend > bp->b_bcount)
 1786                         bp->b_dirtyend = bp->b_bcount;
 1787                 bp->b_flags |= B_RELBUF;  /* don't leave garbage around */
 1788                 brelse(bp);
 1789         } else {
 1790                 vnode_pager_setsize(vp, nsize);
 1791         }
 1792         return(error);
 1793 }
 1794 

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