The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/fs/nfsclient/nfs_clbio.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/9.0/sys/fs/nfsclient/nfs_clbio.c 223280 2011-06-18 23:02:53Z 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/mount.h>
   46 #include <sys/vmmeter.h>
   47 #include <sys/vnode.h>
   48 
   49 #include <vm/vm.h>
   50 #include <vm/vm_extern.h>
   51 #include <vm/vm_page.h>
   52 #include <vm/vm_object.h>
   53 #include <vm/vm_pager.h>
   54 #include <vm/vnode_pager.h>
   55 
   56 #include <fs/nfs/nfsport.h>
   57 #include <fs/nfsclient/nfsmount.h>
   58 #include <fs/nfsclient/nfs.h>
   59 #include <fs/nfsclient/nfsnode.h>
   60 #include <fs/nfsclient/nfs_kdtrace.h>
   61 
   62 extern int newnfs_directio_allow_mmap;
   63 extern struct nfsstats newnfsstats;
   64 extern struct mtx ncl_iod_mutex;
   65 extern int ncl_numasync;
   66 extern enum nfsiod_state ncl_iodwant[NFS_MAXASYNCDAEMON];
   67 extern struct nfsmount *ncl_iodmount[NFS_MAXASYNCDAEMON];
   68 extern int newnfs_directio_enable;
   69 
   70 int ncl_pbuf_freecnt = -1;      /* start out unlimited */
   71 
   72 static struct buf *nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size,
   73     struct thread *td);
   74 static int nfs_directio_write(struct vnode *vp, struct uio *uiop, 
   75     struct ucred *cred, int ioflag);
   76 
   77 /*
   78  * Vnode op for VM getpages.
   79  */
   80 int
   81 ncl_getpages(struct vop_getpages_args *ap)
   82 {
   83         int i, error, nextoff, size, toff, count, npages;
   84         struct uio uio;
   85         struct iovec iov;
   86         vm_offset_t kva;
   87         struct buf *bp;
   88         struct vnode *vp;
   89         struct thread *td;
   90         struct ucred *cred;
   91         struct nfsmount *nmp;
   92         vm_object_t object;
   93         vm_page_t *pages;
   94         struct nfsnode *np;
   95 
   96         vp = ap->a_vp;
   97         np = VTONFS(vp);
   98         td = curthread;                         /* XXX */
   99         cred = curthread->td_ucred;             /* XXX */
  100         nmp = VFSTONFS(vp->v_mount);
  101         pages = ap->a_m;
  102         count = ap->a_count;
  103 
  104         if ((object = vp->v_object) == NULL) {
  105                 ncl_printf("nfs_getpages: called with non-merged cache vnode??\n");
  106                 return (VM_PAGER_ERROR);
  107         }
  108 
  109         if (newnfs_directio_enable && !newnfs_directio_allow_mmap) {
  110                 mtx_lock(&np->n_mtx);
  111                 if ((np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
  112                         mtx_unlock(&np->n_mtx);
  113                         ncl_printf("nfs_getpages: called on non-cacheable vnode??\n");
  114                         return (VM_PAGER_ERROR);
  115                 } else
  116                         mtx_unlock(&np->n_mtx);
  117         }
  118 
  119         mtx_lock(&nmp->nm_mtx);
  120         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  121             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {  
  122                 mtx_unlock(&nmp->nm_mtx);
  123                 /* We'll never get here for v4, because we always have fsinfo */
  124                 (void)ncl_fsinfo(nmp, vp, cred, td);
  125         } else
  126                 mtx_unlock(&nmp->nm_mtx);
  127 
  128         npages = btoc(count);
  129 
  130         /*
  131          * If the requested page is partially valid, just return it and
  132          * allow the pager to zero-out the blanks.  Partially valid pages
  133          * can only occur at the file EOF.
  134          */
  135         VM_OBJECT_LOCK(object);
  136         if (pages[ap->a_reqpage]->valid != 0) {
  137                 for (i = 0; i < npages; ++i) {
  138                         if (i != ap->a_reqpage) {
  139                                 vm_page_lock(pages[i]);
  140                                 vm_page_free(pages[i]);
  141                                 vm_page_unlock(pages[i]);
  142                         }
  143                 }
  144                 VM_OBJECT_UNLOCK(object);
  145                 return (0);
  146         }
  147         VM_OBJECT_UNLOCK(object);
  148 
  149         /*
  150          * We use only the kva address for the buffer, but this is extremely
  151          * convienient and fast.
  152          */
  153         bp = getpbuf(&ncl_pbuf_freecnt);
  154 
  155         kva = (vm_offset_t) bp->b_data;
  156         pmap_qenter(kva, pages, npages);
  157         PCPU_INC(cnt.v_vnodein);
  158         PCPU_ADD(cnt.v_vnodepgsin, npages);
  159 
  160         iov.iov_base = (caddr_t) kva;
  161         iov.iov_len = count;
  162         uio.uio_iov = &iov;
  163         uio.uio_iovcnt = 1;
  164         uio.uio_offset = IDX_TO_OFF(pages[0]->pindex);
  165         uio.uio_resid = count;
  166         uio.uio_segflg = UIO_SYSSPACE;
  167         uio.uio_rw = UIO_READ;
  168         uio.uio_td = td;
  169 
  170         error = ncl_readrpc(vp, &uio, cred);
  171         pmap_qremove(kva, npages);
  172 
  173         relpbuf(bp, &ncl_pbuf_freecnt);
  174 
  175         if (error && (uio.uio_resid == count)) {
  176                 ncl_printf("nfs_getpages: error %d\n", error);
  177                 VM_OBJECT_LOCK(object);
  178                 for (i = 0; i < npages; ++i) {
  179                         if (i != ap->a_reqpage) {
  180                                 vm_page_lock(pages[i]);
  181                                 vm_page_free(pages[i]);
  182                                 vm_page_unlock(pages[i]);
  183                         }
  184                 }
  185                 VM_OBJECT_UNLOCK(object);
  186                 return (VM_PAGER_ERROR);
  187         }
  188 
  189         /*
  190          * Calculate the number of bytes read and validate only that number
  191          * of bytes.  Note that due to pending writes, size may be 0.  This
  192          * does not mean that the remaining data is invalid!
  193          */
  194 
  195         size = count - uio.uio_resid;
  196         VM_OBJECT_LOCK(object);
  197         for (i = 0, toff = 0; i < npages; i++, toff = nextoff) {
  198                 vm_page_t m;
  199                 nextoff = toff + PAGE_SIZE;
  200                 m = pages[i];
  201 
  202                 if (nextoff <= size) {
  203                         /*
  204                          * Read operation filled an entire page
  205                          */
  206                         m->valid = VM_PAGE_BITS_ALL;
  207                         KASSERT(m->dirty == 0,
  208                             ("nfs_getpages: page %p is dirty", m));
  209                 } else if (size > toff) {
  210                         /*
  211                          * Read operation filled a partial page.
  212                          */
  213                         m->valid = 0;
  214                         vm_page_set_valid(m, 0, size - toff);
  215                         KASSERT(m->dirty == 0,
  216                             ("nfs_getpages: page %p is dirty", m));
  217                 } else {
  218                         /*
  219                          * Read operation was short.  If no error occured
  220                          * we may have hit a zero-fill section.   We simply
  221                          * leave valid set to 0.
  222                          */
  223                         ;
  224                 }
  225                 if (i != ap->a_reqpage) {
  226                         /*
  227                          * Whether or not to leave the page activated is up in
  228                          * the air, but we should put the page on a page queue
  229                          * somewhere (it already is in the object).  Result:
  230                          * It appears that emperical results show that
  231                          * deactivating pages is best.
  232                          */
  233 
  234                         /*
  235                          * Just in case someone was asking for this page we
  236                          * now tell them that it is ok to use.
  237                          */
  238                         if (!error) {
  239                                 if (m->oflags & VPO_WANTED) {
  240                                         vm_page_lock(m);
  241                                         vm_page_activate(m);
  242                                         vm_page_unlock(m);
  243                                 } else {
  244                                         vm_page_lock(m);
  245                                         vm_page_deactivate(m);
  246                                         vm_page_unlock(m);
  247                                 }
  248                                 vm_page_wakeup(m);
  249                         } else {
  250                                 vm_page_lock(m);
  251                                 vm_page_free(m);
  252                                 vm_page_unlock(m);
  253                         }
  254                 }
  255         }
  256         VM_OBJECT_UNLOCK(object);
  257         return (0);
  258 }
  259 
  260 /*
  261  * Vnode op for VM putpages.
  262  */
  263 int
  264 ncl_putpages(struct vop_putpages_args *ap)
  265 {
  266         struct uio uio;
  267         struct iovec iov;
  268         vm_offset_t kva;
  269         struct buf *bp;
  270         int iomode, must_commit, i, error, npages, count;
  271         off_t offset;
  272         int *rtvals;
  273         struct vnode *vp;
  274         struct thread *td;
  275         struct ucred *cred;
  276         struct nfsmount *nmp;
  277         struct nfsnode *np;
  278         vm_page_t *pages;
  279 
  280         vp = ap->a_vp;
  281         np = VTONFS(vp);
  282         td = curthread;                         /* XXX */
  283         cred = curthread->td_ucred;             /* XXX */
  284         nmp = VFSTONFS(vp->v_mount);
  285         pages = ap->a_m;
  286         count = ap->a_count;
  287         rtvals = ap->a_rtvals;
  288         npages = btoc(count);
  289         offset = IDX_TO_OFF(pages[0]->pindex);
  290         
  291         mtx_lock(&nmp->nm_mtx);
  292         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  293             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  294                 mtx_unlock(&nmp->nm_mtx);
  295                 (void)ncl_fsinfo(nmp, vp, cred, td);
  296         } else
  297                 mtx_unlock(&nmp->nm_mtx);
  298 
  299         mtx_lock(&np->n_mtx);
  300         if (newnfs_directio_enable && !newnfs_directio_allow_mmap && 
  301             (np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
  302                 mtx_unlock(&np->n_mtx);         
  303                 ncl_printf("ncl_putpages: called on noncache-able vnode??\n");
  304                 mtx_lock(&np->n_mtx);
  305         }
  306 
  307         for (i = 0; i < npages; i++)
  308                 rtvals[i] = VM_PAGER_ERROR;
  309 
  310         /*
  311          * When putting pages, do not extend file past EOF.
  312          */
  313         if (offset + count > np->n_size) {
  314                 count = np->n_size - offset;
  315                 if (count < 0)
  316                         count = 0;
  317         }
  318         mtx_unlock(&np->n_mtx);
  319 
  320         /*
  321          * We use only the kva address for the buffer, but this is extremely
  322          * convienient and fast.
  323          */
  324         bp = getpbuf(&ncl_pbuf_freecnt);
  325 
  326         kva = (vm_offset_t) bp->b_data;
  327         pmap_qenter(kva, pages, npages);
  328         PCPU_INC(cnt.v_vnodeout);
  329         PCPU_ADD(cnt.v_vnodepgsout, count);
  330 
  331         iov.iov_base = (caddr_t) kva;
  332         iov.iov_len = count;
  333         uio.uio_iov = &iov;
  334         uio.uio_iovcnt = 1;
  335         uio.uio_offset = offset;
  336         uio.uio_resid = count;
  337         uio.uio_segflg = UIO_SYSSPACE;
  338         uio.uio_rw = UIO_WRITE;
  339         uio.uio_td = td;
  340 
  341         if ((ap->a_sync & VM_PAGER_PUT_SYNC) == 0)
  342             iomode = NFSWRITE_UNSTABLE;
  343         else
  344             iomode = NFSWRITE_FILESYNC;
  345 
  346         error = ncl_writerpc(vp, &uio, cred, &iomode, &must_commit, 0);
  347 
  348         pmap_qremove(kva, npages);
  349         relpbuf(bp, &ncl_pbuf_freecnt);
  350 
  351         vnode_pager_undirty_pages(pages, rtvals, count - uio.uio_resid);
  352         if (must_commit)
  353                 ncl_clearcommit(vp->v_mount);
  354         return rtvals[0];
  355 }
  356 
  357 /*
  358  * For nfs, cache consistency can only be maintained approximately.
  359  * Although RFC1094 does not specify the criteria, the following is
  360  * believed to be compatible with the reference port.
  361  * For nfs:
  362  * If the file's modify time on the server has changed since the
  363  * last read rpc or you have written to the file,
  364  * you may have lost data cache consistency with the
  365  * server, so flush all of the file's data out of the cache.
  366  * Then force a getattr rpc to ensure that you have up to date
  367  * attributes.
  368  * NB: This implies that cache data can be read when up to
  369  * NFS_ATTRTIMEO seconds out of date. If you find that you need current
  370  * attributes this could be forced by setting n_attrstamp to 0 before
  371  * the VOP_GETATTR() call.
  372  */
  373 static inline int
  374 nfs_bioread_check_cons(struct vnode *vp, struct thread *td, struct ucred *cred)
  375 {
  376         int error = 0;
  377         struct vattr vattr;
  378         struct nfsnode *np = VTONFS(vp);
  379         int old_lock;
  380         
  381         /*
  382          * Grab the exclusive lock before checking whether the cache is
  383          * consistent.
  384          * XXX - We can make this cheaper later (by acquiring cheaper locks).
  385          * But for now, this suffices.
  386          */
  387         old_lock = ncl_upgrade_vnlock(vp);
  388         if (vp->v_iflag & VI_DOOMED) {
  389                 ncl_downgrade_vnlock(vp, old_lock);
  390                 return (EBADF);
  391         }
  392 
  393         mtx_lock(&np->n_mtx);
  394         if (np->n_flag & NMODIFIED) {
  395                 mtx_unlock(&np->n_mtx);
  396                 if (vp->v_type != VREG) {
  397                         if (vp->v_type != VDIR)
  398                                 panic("nfs: bioread, not dir");
  399                         ncl_invaldir(vp);
  400                         error = ncl_vinvalbuf(vp, V_SAVE, td, 1);
  401                         if (error)
  402                                 goto out;
  403                 }
  404                 np->n_attrstamp = 0;
  405                 KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  406                 error = VOP_GETATTR(vp, &vattr, cred);
  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);
  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                                 ncl_invaldir(vp);
  423                         error = ncl_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         ncl_downgrade_vnlock(vp, old_lock);
  434         return error;
  435 }
  436 
  437 /*
  438  * Vnode op for read using bio
  439  */
  440 int
  441 ncl_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         off_t tmp_off;
  453 
  454         KASSERT(uio->uio_rw == UIO_READ, ("ncl_read mode"));
  455         if (uio->uio_resid == 0)
  456                 return (0);
  457         if (uio->uio_offset < 0)        /* XXX VDIR cookies can be negative */
  458                 return (EINVAL);
  459         td = uio->uio_td;
  460 
  461         mtx_lock(&nmp->nm_mtx);
  462         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  463             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  464                 mtx_unlock(&nmp->nm_mtx);
  465                 (void)ncl_fsinfo(nmp, vp, cred, td);
  466                 mtx_lock(&nmp->nm_mtx);
  467         }
  468         if (nmp->nm_rsize == 0 || nmp->nm_readdirsize == 0)
  469                 (void) newnfs_iosize(nmp);
  470 
  471         tmp_off = uio->uio_offset + uio->uio_resid;
  472         if (vp->v_type != VDIR &&
  473             (tmp_off > nmp->nm_maxfilesize || tmp_off < uio->uio_offset)) {
  474                 mtx_unlock(&nmp->nm_mtx);               
  475                 return (EFBIG);
  476         }
  477         mtx_unlock(&nmp->nm_mtx);               
  478 
  479         if (newnfs_directio_enable && (ioflag & IO_DIRECT) && (vp->v_type == VREG))
  480                 /* No caching/ no readaheads. Just read data into the user buffer */
  481                 return ncl_readrpc(vp, uio, cred);
  482 
  483         biosize = vp->v_mount->mnt_stat.f_iosize;
  484         seqcount = (int)((off_t)(ioflag >> IO_SEQSHIFT) * biosize / BKVASIZE);
  485         
  486         error = nfs_bioread_check_cons(vp, td, cred);
  487         if (error)
  488                 return error;
  489 
  490         do {
  491             u_quad_t nsize;
  492                         
  493             mtx_lock(&np->n_mtx);
  494             nsize = np->n_size;
  495             mtx_unlock(&np->n_mtx);                 
  496 
  497             switch (vp->v_type) {
  498             case VREG:
  499                 NFSINCRGLOBAL(newnfsstats.biocache_reads);
  500                 lbn = uio->uio_offset / biosize;
  501                 on = uio->uio_offset & (biosize - 1);
  502 
  503                 /*
  504                  * Start the read ahead(s), as required.
  505                  */
  506                 if (nmp->nm_readahead > 0) {
  507                     for (nra = 0; nra < nmp->nm_readahead && nra < seqcount &&
  508                         (off_t)(lbn + 1 + nra) * biosize < nsize; nra++) {
  509                         rabn = lbn + 1 + nra;
  510                         if (incore(&vp->v_bufobj, rabn) == NULL) {
  511                             rabp = nfs_getcacheblk(vp, rabn, biosize, td);
  512                             if (!rabp) {
  513                                 error = newnfs_sigintr(nmp, td);
  514                                 return (error ? error : EINTR);
  515                             }
  516                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  517                                 rabp->b_flags |= B_ASYNC;
  518                                 rabp->b_iocmd = BIO_READ;
  519                                 vfs_busy_pages(rabp, 0);
  520                                 if (ncl_asyncio(nmp, rabp, cred, td)) {
  521                                     rabp->b_flags |= B_INVAL;
  522                                     rabp->b_ioflags |= BIO_ERROR;
  523                                     vfs_unbusy_pages(rabp);
  524                                     brelse(rabp);
  525                                     break;
  526                                 }
  527                             } else {
  528                                 brelse(rabp);
  529                             }
  530                         }
  531                     }
  532                 }
  533 
  534                 /* Note that bcount is *not* DEV_BSIZE aligned. */
  535                 bcount = biosize;
  536                 if ((off_t)lbn * biosize >= nsize) {
  537                         bcount = 0;
  538                 } else if ((off_t)(lbn + 1) * biosize > nsize) {
  539                         bcount = nsize - (off_t)lbn * biosize;
  540                 }
  541                 bp = nfs_getcacheblk(vp, lbn, bcount, td);
  542 
  543                 if (!bp) {
  544                         error = newnfs_sigintr(nmp, td);
  545                         return (error ? error : EINTR);
  546                 }
  547 
  548                 /*
  549                  * If B_CACHE is not set, we must issue the read.  If this
  550                  * fails, we return an error.
  551                  */
  552 
  553                 if ((bp->b_flags & B_CACHE) == 0) {
  554                     bp->b_iocmd = BIO_READ;
  555                     vfs_busy_pages(bp, 0);
  556                     error = ncl_doio(vp, bp, cred, td, 0);
  557                     if (error) {
  558                         brelse(bp);
  559                         return (error);
  560                     }
  561                 }
  562 
  563                 /*
  564                  * on is the offset into the current bp.  Figure out how many
  565                  * bytes we can copy out of the bp.  Note that bcount is
  566                  * NOT DEV_BSIZE aligned.
  567                  *
  568                  * Then figure out how many bytes we can copy into the uio.
  569                  */
  570 
  571                 n = 0;
  572                 if (on < bcount)
  573                         n = min((unsigned)(bcount - on), uio->uio_resid);
  574                 break;
  575             case VLNK:
  576                 NFSINCRGLOBAL(newnfsstats.biocache_readlinks);
  577                 bp = nfs_getcacheblk(vp, (daddr_t)0, NFS_MAXPATHLEN, td);
  578                 if (!bp) {
  579                         error = newnfs_sigintr(nmp, td);
  580                         return (error ? error : EINTR);
  581                 }
  582                 if ((bp->b_flags & B_CACHE) == 0) {
  583                     bp->b_iocmd = BIO_READ;
  584                     vfs_busy_pages(bp, 0);
  585                     error = ncl_doio(vp, bp, cred, td, 0);
  586                     if (error) {
  587                         bp->b_ioflags |= BIO_ERROR;
  588                         brelse(bp);
  589                         return (error);
  590                     }
  591                 }
  592                 n = min(uio->uio_resid, NFS_MAXPATHLEN - bp->b_resid);
  593                 on = 0;
  594                 break;
  595             case VDIR:
  596                 NFSINCRGLOBAL(newnfsstats.biocache_readdirs);
  597                 if (np->n_direofoffset
  598                     && uio->uio_offset >= np->n_direofoffset) {
  599                     return (0);
  600                 }
  601                 lbn = (uoff_t)uio->uio_offset / NFS_DIRBLKSIZ;
  602                 on = uio->uio_offset & (NFS_DIRBLKSIZ - 1);
  603                 bp = nfs_getcacheblk(vp, lbn, NFS_DIRBLKSIZ, td);
  604                 if (!bp) {
  605                     error = newnfs_sigintr(nmp, td);
  606                     return (error ? error : EINTR);
  607                 }
  608                 if ((bp->b_flags & B_CACHE) == 0) {
  609                     bp->b_iocmd = BIO_READ;
  610                     vfs_busy_pages(bp, 0);
  611                     error = ncl_doio(vp, bp, cred, td, 0);
  612                     if (error) {
  613                             brelse(bp);
  614                     }
  615                     while (error == NFSERR_BAD_COOKIE) {
  616                         ncl_invaldir(vp);
  617                         error = ncl_vinvalbuf(vp, 0, td, 1);
  618                         /*
  619                          * Yuck! The directory has been modified on the
  620                          * server. The only way to get the block is by
  621                          * reading from the beginning to get all the
  622                          * offset cookies.
  623                          *
  624                          * Leave the last bp intact unless there is an error.
  625                          * Loop back up to the while if the error is another
  626                          * NFSERR_BAD_COOKIE (double yuch!).
  627                          */
  628                         for (i = 0; i <= lbn && !error; i++) {
  629                             if (np->n_direofoffset
  630                                 && (i * NFS_DIRBLKSIZ) >= np->n_direofoffset)
  631                                     return (0);
  632                             bp = nfs_getcacheblk(vp, i, NFS_DIRBLKSIZ, td);
  633                             if (!bp) {
  634                                 error = newnfs_sigintr(nmp, td);
  635                                 return (error ? error : EINTR);
  636                             }
  637                             if ((bp->b_flags & B_CACHE) == 0) {
  638                                     bp->b_iocmd = BIO_READ;
  639                                     vfs_busy_pages(bp, 0);
  640                                     error = ncl_doio(vp, bp, cred, td, 0);
  641                                     /*
  642                                      * no error + B_INVAL == directory EOF,
  643                                      * use the block.
  644                                      */
  645                                     if (error == 0 && (bp->b_flags & B_INVAL))
  646                                             break;
  647                             }
  648                             /*
  649                              * An error will throw away the block and the
  650                              * for loop will break out.  If no error and this
  651                              * is not the block we want, we throw away the
  652                              * block and go for the next one via the for loop.
  653                              */
  654                             if (error || i < lbn)
  655                                     brelse(bp);
  656                         }
  657                     }
  658                     /*
  659                      * The above while is repeated if we hit another cookie
  660                      * error.  If we hit an error and it wasn't a cookie error,
  661                      * we give up.
  662                      */
  663                     if (error)
  664                             return (error);
  665                 }
  666 
  667                 /*
  668                  * If not eof and read aheads are enabled, start one.
  669                  * (You need the current block first, so that you have the
  670                  *  directory offset cookie of the next block.)
  671                  */
  672                 if (nmp->nm_readahead > 0 &&
  673                     (bp->b_flags & B_INVAL) == 0 &&
  674                     (np->n_direofoffset == 0 ||
  675                     (lbn + 1) * NFS_DIRBLKSIZ < np->n_direofoffset) &&
  676                     incore(&vp->v_bufobj, lbn + 1) == NULL) {
  677                         rabp = nfs_getcacheblk(vp, lbn + 1, NFS_DIRBLKSIZ, td);
  678                         if (rabp) {
  679                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  680                                 rabp->b_flags |= B_ASYNC;
  681                                 rabp->b_iocmd = BIO_READ;
  682                                 vfs_busy_pages(rabp, 0);
  683                                 if (ncl_asyncio(nmp, rabp, cred, td)) {
  684                                     rabp->b_flags |= B_INVAL;
  685                                     rabp->b_ioflags |= BIO_ERROR;
  686                                     vfs_unbusy_pages(rabp);
  687                                     brelse(rabp);
  688                                 }
  689                             } else {
  690                                 brelse(rabp);
  691                             }
  692                         }
  693                 }
  694                 /*
  695                  * Unlike VREG files, whos buffer size ( bp->b_bcount ) is
  696                  * chopped for the EOF condition, we cannot tell how large
  697                  * NFS directories are going to be until we hit EOF.  So
  698                  * an NFS directory buffer is *not* chopped to its EOF.  Now,
  699                  * it just so happens that b_resid will effectively chop it
  700                  * to EOF.  *BUT* this information is lost if the buffer goes
  701                  * away and is reconstituted into a B_CACHE state ( due to
  702                  * being VMIO ) later.  So we keep track of the directory eof
  703                  * in np->n_direofoffset and chop it off as an extra step
  704                  * right here.
  705                  */
  706                 n = lmin(uio->uio_resid, NFS_DIRBLKSIZ - bp->b_resid - on);
  707                 if (np->n_direofoffset && n > np->n_direofoffset - uio->uio_offset)
  708                         n = np->n_direofoffset - uio->uio_offset;
  709                 break;
  710             default:
  711                 ncl_printf(" ncl_bioread: type %x unexpected\n", vp->v_type);
  712                 bp = NULL;
  713                 break;
  714             };
  715 
  716             if (n > 0) {
  717                     error = uiomove(bp->b_data + on, (int)n, uio);
  718             }
  719             if (vp->v_type == VLNK)
  720                 n = 0;
  721             if (bp != NULL)
  722                 brelse(bp);
  723         } while (error == 0 && uio->uio_resid > 0 && n > 0);
  724         return (error);
  725 }
  726 
  727 /*
  728  * The NFS write path cannot handle iovecs with len > 1. So we need to 
  729  * break up iovecs accordingly (restricting them to wsize).
  730  * For the SYNC case, we can do this with 1 copy (user buffer -> mbuf). 
  731  * For the ASYNC case, 2 copies are needed. The first a copy from the 
  732  * user buffer to a staging buffer and then a second copy from the staging
  733  * buffer to mbufs. This can be optimized by copying from the user buffer
  734  * directly into mbufs and passing the chain down, but that requires a 
  735  * fair amount of re-working of the relevant codepaths (and can be done
  736  * later).
  737  */
  738 static int
  739 nfs_directio_write(vp, uiop, cred, ioflag)
  740         struct vnode *vp;
  741         struct uio *uiop;
  742         struct ucred *cred;
  743         int ioflag;
  744 {
  745         int error;
  746         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  747         struct thread *td = uiop->uio_td;
  748         int size;
  749         int wsize;
  750         
  751         mtx_lock(&nmp->nm_mtx);
  752         wsize = nmp->nm_wsize;
  753         mtx_unlock(&nmp->nm_mtx);
  754         if (ioflag & IO_SYNC) {
  755                 int iomode, must_commit;
  756                 struct uio uio;
  757                 struct iovec iov;
  758 do_sync:
  759                 while (uiop->uio_resid > 0) {
  760                         size = min(uiop->uio_resid, wsize);
  761                         size = min(uiop->uio_iov->iov_len, size);
  762                         iov.iov_base = uiop->uio_iov->iov_base;
  763                         iov.iov_len = size;
  764                         uio.uio_iov = &iov;
  765                         uio.uio_iovcnt = 1;
  766                         uio.uio_offset = uiop->uio_offset;
  767                         uio.uio_resid = size;
  768                         uio.uio_segflg = UIO_USERSPACE;
  769                         uio.uio_rw = UIO_WRITE;
  770                         uio.uio_td = td;
  771                         iomode = NFSWRITE_FILESYNC;
  772                         error = ncl_writerpc(vp, &uio, cred, &iomode,
  773                             &must_commit, 0);
  774                         KASSERT((must_commit == 0), 
  775                                 ("ncl_directio_write: Did not commit write"));
  776                         if (error)
  777                                 return (error);
  778                         uiop->uio_offset += size;
  779                         uiop->uio_resid -= size;
  780                         if (uiop->uio_iov->iov_len <= size) {
  781                                 uiop->uio_iovcnt--;
  782                                 uiop->uio_iov++;
  783                         } else {
  784                                 uiop->uio_iov->iov_base = 
  785                                         (char *)uiop->uio_iov->iov_base + size;
  786                                 uiop->uio_iov->iov_len -= size;
  787                         }
  788                 }
  789         } else {
  790                 struct uio *t_uio;
  791                 struct iovec *t_iov;
  792                 struct buf *bp;
  793                 
  794                 /*
  795                  * Break up the write into blocksize chunks and hand these
  796                  * over to nfsiod's for write back.
  797                  * Unfortunately, this incurs a copy of the data. Since 
  798                  * the user could modify the buffer before the write is 
  799                  * initiated.
  800                  * 
  801                  * The obvious optimization here is that one of the 2 copies
  802                  * in the async write path can be eliminated by copying the
  803                  * data here directly into mbufs and passing the mbuf chain
  804                  * down. But that will require a fair amount of re-working
  805                  * of the code and can be done if there's enough interest
  806                  * in NFS directio access.
  807                  */
  808                 while (uiop->uio_resid > 0) {
  809                         size = min(uiop->uio_resid, wsize);
  810                         size = min(uiop->uio_iov->iov_len, size);
  811                         bp = getpbuf(&ncl_pbuf_freecnt);
  812                         t_uio = malloc(sizeof(struct uio), M_NFSDIRECTIO, M_WAITOK);
  813                         t_iov = malloc(sizeof(struct iovec), M_NFSDIRECTIO, M_WAITOK);
  814                         t_iov->iov_base = malloc(size, M_NFSDIRECTIO, M_WAITOK);
  815                         t_iov->iov_len = size;
  816                         t_uio->uio_iov = t_iov;
  817                         t_uio->uio_iovcnt = 1;
  818                         t_uio->uio_offset = uiop->uio_offset;
  819                         t_uio->uio_resid = size;
  820                         t_uio->uio_segflg = UIO_SYSSPACE;
  821                         t_uio->uio_rw = UIO_WRITE;
  822                         t_uio->uio_td = td;
  823                         bcopy(uiop->uio_iov->iov_base, t_iov->iov_base, size);
  824                         bp->b_flags |= B_DIRECT;
  825                         bp->b_iocmd = BIO_WRITE;
  826                         if (cred != NOCRED) {
  827                                 crhold(cred);
  828                                 bp->b_wcred = cred;
  829                         } else 
  830                                 bp->b_wcred = NOCRED;                   
  831                         bp->b_caller1 = (void *)t_uio;
  832                         bp->b_vp = vp;
  833                         error = ncl_asyncio(nmp, bp, NOCRED, td);
  834                         if (error) {
  835                                 free(t_iov->iov_base, M_NFSDIRECTIO);
  836                                 free(t_iov, M_NFSDIRECTIO);
  837                                 free(t_uio, M_NFSDIRECTIO);
  838                                 bp->b_vp = NULL;
  839                                 relpbuf(bp, &ncl_pbuf_freecnt);
  840                                 if (error == EINTR)
  841                                         return (error);
  842                                 goto do_sync;
  843                         }
  844                         uiop->uio_offset += size;
  845                         uiop->uio_resid -= size;
  846                         if (uiop->uio_iov->iov_len <= size) {
  847                                 uiop->uio_iovcnt--;
  848                                 uiop->uio_iov++;
  849                         } else {
  850                                 uiop->uio_iov->iov_base = 
  851                                         (char *)uiop->uio_iov->iov_base + size;
  852                                 uiop->uio_iov->iov_len -= size;
  853                         }
  854                 }
  855         }
  856         return (0);
  857 }
  858 
  859 /*
  860  * Vnode op for write using bio
  861  */
  862 int
  863 ncl_write(struct vop_write_args *ap)
  864 {
  865         int biosize;
  866         struct uio *uio = ap->a_uio;
  867         struct thread *td = uio->uio_td;
  868         struct vnode *vp = ap->a_vp;
  869         struct nfsnode *np = VTONFS(vp);
  870         struct ucred *cred = ap->a_cred;
  871         int ioflag = ap->a_ioflag;
  872         struct buf *bp;
  873         struct vattr vattr;
  874         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  875         daddr_t lbn;
  876         int bcount;
  877         int n, on, error = 0;
  878         off_t tmp_off;
  879 
  880         KASSERT(uio->uio_rw == UIO_WRITE, ("ncl_write mode"));
  881         KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
  882             ("ncl_write proc"));
  883         if (vp->v_type != VREG)
  884                 return (EIO);
  885         mtx_lock(&np->n_mtx);
  886         if (np->n_flag & NWRITEERR) {
  887                 np->n_flag &= ~NWRITEERR;
  888                 mtx_unlock(&np->n_mtx);
  889                 return (np->n_error);
  890         } else
  891                 mtx_unlock(&np->n_mtx);
  892         mtx_lock(&nmp->nm_mtx);
  893         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  894             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  895                 mtx_unlock(&nmp->nm_mtx);
  896                 (void)ncl_fsinfo(nmp, vp, cred, td);
  897                 mtx_lock(&nmp->nm_mtx);
  898         }
  899         if (nmp->nm_wsize == 0)
  900                 (void) newnfs_iosize(nmp);
  901         mtx_unlock(&nmp->nm_mtx);
  902 
  903         /*
  904          * Synchronously flush pending buffers if we are in synchronous
  905          * mode or if we are appending.
  906          */
  907         if (ioflag & (IO_APPEND | IO_SYNC)) {
  908                 mtx_lock(&np->n_mtx);
  909                 if (np->n_flag & NMODIFIED) {
  910                         mtx_unlock(&np->n_mtx);
  911 #ifdef notyet /* Needs matching nonblock semantics elsewhere, too. */
  912                         /*
  913                          * Require non-blocking, synchronous writes to
  914                          * dirty files to inform the program it needs
  915                          * to fsync(2) explicitly.
  916                          */
  917                         if (ioflag & IO_NDELAY)
  918                                 return (EAGAIN);
  919 #endif
  920 flush_and_restart:
  921                         np->n_attrstamp = 0;
  922                         KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  923                         error = ncl_vinvalbuf(vp, V_SAVE, td, 1);
  924                         if (error)
  925                                 return (error);
  926                 } else
  927                         mtx_unlock(&np->n_mtx);
  928         }
  929 
  930         /*
  931          * If IO_APPEND then load uio_offset.  We restart here if we cannot
  932          * get the append lock.
  933          */
  934         if (ioflag & IO_APPEND) {
  935                 np->n_attrstamp = 0;
  936                 KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  937                 error = VOP_GETATTR(vp, &vattr, cred);
  938                 if (error)
  939                         return (error);
  940                 mtx_lock(&np->n_mtx);
  941                 uio->uio_offset = np->n_size;
  942                 mtx_unlock(&np->n_mtx);
  943         }
  944 
  945         if (uio->uio_offset < 0)
  946                 return (EINVAL);
  947         tmp_off = uio->uio_offset + uio->uio_resid;
  948         if (tmp_off > nmp->nm_maxfilesize || tmp_off < uio->uio_offset)
  949                 return (EFBIG);
  950         if (uio->uio_resid == 0)
  951                 return (0);
  952 
  953         if (newnfs_directio_enable && (ioflag & IO_DIRECT) && vp->v_type == VREG)
  954                 return nfs_directio_write(vp, uio, cred, ioflag);
  955 
  956         /*
  957          * Maybe this should be above the vnode op call, but so long as
  958          * file servers have no limits, i don't think it matters
  959          */
  960         if (vn_rlimit_fsize(vp, uio, td))
  961                 return (EFBIG);
  962 
  963         biosize = vp->v_mount->mnt_stat.f_iosize;
  964         /*
  965          * Find all of this file's B_NEEDCOMMIT buffers.  If our writes
  966          * would exceed the local maximum per-file write commit size when
  967          * combined with those, we must decide whether to flush,
  968          * go synchronous, or return error.  We don't bother checking
  969          * IO_UNIT -- we just make all writes atomic anyway, as there's
  970          * no point optimizing for something that really won't ever happen.
  971          */
  972         if (!(ioflag & IO_SYNC)) {
  973                 int nflag;
  974 
  975                 mtx_lock(&np->n_mtx);
  976                 nflag = np->n_flag;
  977                 mtx_unlock(&np->n_mtx);         
  978                 int needrestart = 0;
  979                 if (nmp->nm_wcommitsize < uio->uio_resid) {
  980                         /*
  981                          * If this request could not possibly be completed
  982                          * without exceeding the maximum outstanding write
  983                          * commit size, see if we can convert it into a
  984                          * synchronous write operation.
  985                          */
  986                         if (ioflag & IO_NDELAY)
  987                                 return (EAGAIN);
  988                         ioflag |= IO_SYNC;
  989                         if (nflag & NMODIFIED)
  990                                 needrestart = 1;
  991                 } else if (nflag & NMODIFIED) {
  992                         int wouldcommit = 0;
  993                         BO_LOCK(&vp->v_bufobj);
  994                         if (vp->v_bufobj.bo_dirty.bv_cnt != 0) {
  995                                 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd,
  996                                     b_bobufs) {
  997                                         if (bp->b_flags & B_NEEDCOMMIT)
  998                                                 wouldcommit += bp->b_bcount;
  999                                 }
 1000                         }
 1001                         BO_UNLOCK(&vp->v_bufobj);
 1002                         /*
 1003                          * Since we're not operating synchronously and
 1004                          * bypassing the buffer cache, we are in a commit
 1005                          * and holding all of these buffers whether
 1006                          * transmitted or not.  If not limited, this
 1007                          * will lead to the buffer cache deadlocking,
 1008                          * as no one else can flush our uncommitted buffers.
 1009                          */
 1010                         wouldcommit += uio->uio_resid;
 1011                         /*
 1012                          * If we would initially exceed the maximum
 1013                          * outstanding write commit size, flush and restart.
 1014                          */
 1015                         if (wouldcommit > nmp->nm_wcommitsize)
 1016                                 needrestart = 1;
 1017                 }
 1018                 if (needrestart)
 1019                         goto flush_and_restart;
 1020         }
 1021 
 1022         do {
 1023                 NFSINCRGLOBAL(newnfsstats.biocache_writes);
 1024                 lbn = uio->uio_offset / biosize;
 1025                 on = uio->uio_offset & (biosize-1);
 1026                 n = min((unsigned)(biosize - on), uio->uio_resid);
 1027 again:
 1028                 /*
 1029                  * Handle direct append and file extension cases, calculate
 1030                  * unaligned buffer size.
 1031                  */
 1032                 mtx_lock(&np->n_mtx);
 1033                 if (uio->uio_offset == np->n_size && n) {
 1034                         mtx_unlock(&np->n_mtx);
 1035                         /*
 1036                          * Get the buffer (in its pre-append state to maintain
 1037                          * B_CACHE if it was previously set).  Resize the
 1038                          * nfsnode after we have locked the buffer to prevent
 1039                          * readers from reading garbage.
 1040                          */
 1041                         bcount = on;
 1042                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1043 
 1044                         if (bp != NULL) {
 1045                                 long save;
 1046 
 1047                                 mtx_lock(&np->n_mtx);
 1048                                 np->n_size = uio->uio_offset + n;
 1049                                 np->n_flag |= NMODIFIED;
 1050                                 vnode_pager_setsize(vp, np->n_size);
 1051                                 mtx_unlock(&np->n_mtx);
 1052 
 1053                                 save = bp->b_flags & B_CACHE;
 1054                                 bcount += n;
 1055                                 allocbuf(bp, bcount);
 1056                                 bp->b_flags |= save;
 1057                         }
 1058                 } else {
 1059                         /*
 1060                          * Obtain the locked cache block first, and then
 1061                          * adjust the file's size as appropriate.
 1062                          */
 1063                         bcount = on + n;
 1064                         if ((off_t)lbn * biosize + bcount < np->n_size) {
 1065                                 if ((off_t)(lbn + 1) * biosize < np->n_size)
 1066                                         bcount = biosize;
 1067                                 else
 1068                                         bcount = np->n_size - (off_t)lbn * biosize;
 1069                         }
 1070                         mtx_unlock(&np->n_mtx);
 1071                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1072                         mtx_lock(&np->n_mtx);
 1073                         if (uio->uio_offset + n > np->n_size) {
 1074                                 np->n_size = uio->uio_offset + n;
 1075                                 np->n_flag |= NMODIFIED;
 1076                                 vnode_pager_setsize(vp, np->n_size);
 1077                         }
 1078                         mtx_unlock(&np->n_mtx);
 1079                 }
 1080 
 1081                 if (!bp) {
 1082                         error = newnfs_sigintr(nmp, td);
 1083                         if (!error)
 1084                                 error = EINTR;
 1085                         break;
 1086                 }
 1087 
 1088                 /*
 1089                  * Issue a READ if B_CACHE is not set.  In special-append
 1090                  * mode, B_CACHE is based on the buffer prior to the write
 1091                  * op and is typically set, avoiding the read.  If a read
 1092                  * is required in special append mode, the server will
 1093                  * probably send us a short-read since we extended the file
 1094                  * on our end, resulting in b_resid == 0 and, thusly,
 1095                  * B_CACHE getting set.
 1096                  *
 1097                  * We can also avoid issuing the read if the write covers
 1098                  * the entire buffer.  We have to make sure the buffer state
 1099                  * is reasonable in this case since we will not be initiating
 1100                  * I/O.  See the comments in kern/vfs_bio.c's getblk() for
 1101                  * more information.
 1102                  *
 1103                  * B_CACHE may also be set due to the buffer being cached
 1104                  * normally.
 1105                  */
 1106 
 1107                 if (on == 0 && n == bcount) {
 1108                         bp->b_flags |= B_CACHE;
 1109                         bp->b_flags &= ~B_INVAL;
 1110                         bp->b_ioflags &= ~BIO_ERROR;
 1111                 }
 1112 
 1113                 if ((bp->b_flags & B_CACHE) == 0) {
 1114                         bp->b_iocmd = BIO_READ;
 1115                         vfs_busy_pages(bp, 0);
 1116                         error = ncl_doio(vp, bp, cred, td, 0);
 1117                         if (error) {
 1118                                 brelse(bp);
 1119                                 break;
 1120                         }
 1121                 }
 1122                 if (bp->b_wcred == NOCRED)
 1123                         bp->b_wcred = crhold(cred);
 1124                 mtx_lock(&np->n_mtx);
 1125                 np->n_flag |= NMODIFIED;
 1126                 mtx_unlock(&np->n_mtx);
 1127 
 1128                 /*
 1129                  * If dirtyend exceeds file size, chop it down.  This should
 1130                  * not normally occur but there is an append race where it
 1131                  * might occur XXX, so we log it.
 1132                  *
 1133                  * If the chopping creates a reverse-indexed or degenerate
 1134                  * situation with dirtyoff/end, we 0 both of them.
 1135                  */
 1136 
 1137                 if (bp->b_dirtyend > bcount) {
 1138                         ncl_printf("NFS append race @%lx:%d\n",
 1139                             (long)bp->b_blkno * DEV_BSIZE,
 1140                             bp->b_dirtyend - bcount);
 1141                         bp->b_dirtyend = bcount;
 1142                 }
 1143 
 1144                 if (bp->b_dirtyoff >= bp->b_dirtyend)
 1145                         bp->b_dirtyoff = bp->b_dirtyend = 0;
 1146 
 1147                 /*
 1148                  * If the new write will leave a contiguous dirty
 1149                  * area, just update the b_dirtyoff and b_dirtyend,
 1150                  * otherwise force a write rpc of the old dirty area.
 1151                  *
 1152                  * While it is possible to merge discontiguous writes due to
 1153                  * our having a B_CACHE buffer ( and thus valid read data
 1154                  * for the hole), we don't because it could lead to
 1155                  * significant cache coherency problems with multiple clients,
 1156                  * especially if locking is implemented later on.
 1157                  *
 1158                  * as an optimization we could theoretically maintain
 1159                  * a linked list of discontinuous areas, but we would still
 1160                  * have to commit them separately so there isn't much
 1161                  * advantage to it except perhaps a bit of asynchronization.
 1162                  */
 1163 
 1164                 if (bp->b_dirtyend > 0 &&
 1165                     (on > bp->b_dirtyend || (on + n) < bp->b_dirtyoff)) {
 1166                         if (bwrite(bp) == EINTR) {
 1167                                 error = EINTR;
 1168                                 break;
 1169                         }
 1170                         goto again;
 1171                 }
 1172 
 1173                 error = uiomove((char *)bp->b_data + on, n, uio);
 1174 
 1175                 /*
 1176                  * Since this block is being modified, it must be written
 1177                  * again and not just committed.  Since write clustering does
 1178                  * not work for the stage 1 data write, only the stage 2
 1179                  * commit rpc, we have to clear B_CLUSTEROK as well.
 1180                  */
 1181                 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1182 
 1183                 if (error) {
 1184                         bp->b_ioflags |= BIO_ERROR;
 1185                         brelse(bp);
 1186                         break;
 1187                 }
 1188 
 1189                 /*
 1190                  * Only update dirtyoff/dirtyend if not a degenerate
 1191                  * condition.
 1192                  */
 1193                 if (n) {
 1194                         if (bp->b_dirtyend > 0) {
 1195                                 bp->b_dirtyoff = min(on, bp->b_dirtyoff);
 1196                                 bp->b_dirtyend = max((on + n), bp->b_dirtyend);
 1197                         } else {
 1198                                 bp->b_dirtyoff = on;
 1199                                 bp->b_dirtyend = on + n;
 1200                         }
 1201                         vfs_bio_set_valid(bp, on, n);
 1202                 }
 1203 
 1204                 /*
 1205                  * If IO_SYNC do bwrite().
 1206                  *
 1207                  * IO_INVAL appears to be unused.  The idea appears to be
 1208                  * to turn off caching in this case.  Very odd.  XXX
 1209                  */
 1210                 if ((ioflag & IO_SYNC)) {
 1211                         if (ioflag & IO_INVAL)
 1212                                 bp->b_flags |= B_NOCACHE;
 1213                         error = bwrite(bp);
 1214                         if (error)
 1215                                 break;
 1216                 } else if ((n + on) == biosize) {
 1217                         bp->b_flags |= B_ASYNC;
 1218                         (void) ncl_writebp(bp, 0, NULL);
 1219                 } else {
 1220                         bdwrite(bp);
 1221                 }
 1222         } while (uio->uio_resid > 0 && n > 0);
 1223 
 1224         return (error);
 1225 }
 1226 
 1227 /*
 1228  * Get an nfs cache block.
 1229  *
 1230  * Allocate a new one if the block isn't currently in the cache
 1231  * and return the block marked busy. If the calling process is
 1232  * interrupted by a signal for an interruptible mount point, return
 1233  * NULL.
 1234  *
 1235  * The caller must carefully deal with the possible B_INVAL state of
 1236  * the buffer.  ncl_doio() clears B_INVAL (and ncl_asyncio() clears it
 1237  * indirectly), so synchronous reads can be issued without worrying about
 1238  * the B_INVAL state.  We have to be a little more careful when dealing
 1239  * with writes (see comments in nfs_write()) when extending a file past
 1240  * its EOF.
 1241  */
 1242 static struct buf *
 1243 nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size, struct thread *td)
 1244 {
 1245         struct buf *bp;
 1246         struct mount *mp;
 1247         struct nfsmount *nmp;
 1248 
 1249         mp = vp->v_mount;
 1250         nmp = VFSTONFS(mp);
 1251 
 1252         if (nmp->nm_flag & NFSMNT_INT) {
 1253                 sigset_t oldset;
 1254 
 1255                 newnfs_set_sigmask(td, &oldset);
 1256                 bp = getblk(vp, bn, size, NFS_PCATCH, 0, 0);
 1257                 newnfs_restore_sigmask(td, &oldset);
 1258                 while (bp == NULL) {
 1259                         if (newnfs_sigintr(nmp, td))
 1260                                 return (NULL);
 1261                         bp = getblk(vp, bn, size, 0, 2 * hz, 0);
 1262                 }
 1263         } else {
 1264                 bp = getblk(vp, bn, size, 0, 0, 0);
 1265         }
 1266 
 1267         if (vp->v_type == VREG) {
 1268                 int biosize;
 1269 
 1270                 biosize = mp->mnt_stat.f_iosize;
 1271                 bp->b_blkno = bn * (biosize / DEV_BSIZE);
 1272         }
 1273         return (bp);
 1274 }
 1275 
 1276 /*
 1277  * Flush and invalidate all dirty buffers. If another process is already
 1278  * doing the flush, just wait for completion.
 1279  */
 1280 int
 1281 ncl_vinvalbuf(struct vnode *vp, int flags, struct thread *td, int intrflg)
 1282 {
 1283         struct nfsnode *np = VTONFS(vp);
 1284         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
 1285         int error = 0, slpflag, slptimeo;
 1286         int old_lock = 0;
 1287 
 1288         ASSERT_VOP_LOCKED(vp, "ncl_vinvalbuf");
 1289 
 1290         if ((nmp->nm_flag & NFSMNT_INT) == 0)
 1291                 intrflg = 0;
 1292         if ((nmp->nm_mountp->mnt_kern_flag & MNTK_UNMOUNTF))
 1293                 intrflg = 1;
 1294         if (intrflg) {
 1295                 slpflag = NFS_PCATCH;
 1296                 slptimeo = 2 * hz;
 1297         } else {
 1298                 slpflag = 0;
 1299                 slptimeo = 0;
 1300         }
 1301 
 1302         old_lock = ncl_upgrade_vnlock(vp);
 1303         if (vp->v_iflag & VI_DOOMED) {
 1304                 /*
 1305                  * Since vgonel() uses the generic vinvalbuf() to flush
 1306                  * dirty buffers and it does not call this function, it
 1307                  * is safe to just return OK when VI_DOOMED is set.
 1308                  */
 1309                 ncl_downgrade_vnlock(vp, old_lock);
 1310                 return (0);
 1311         }
 1312 
 1313         /*
 1314          * Now, flush as required.
 1315          */
 1316         if ((flags & V_SAVE) && (vp->v_bufobj.bo_object != NULL)) {
 1317                 VM_OBJECT_LOCK(vp->v_bufobj.bo_object);
 1318                 vm_object_page_clean(vp->v_bufobj.bo_object, 0, 0, OBJPC_SYNC);
 1319                 VM_OBJECT_UNLOCK(vp->v_bufobj.bo_object);
 1320                 /*
 1321                  * If the page clean was interrupted, fail the invalidation.
 1322                  * Not doing so, we run the risk of losing dirty pages in the 
 1323                  * vinvalbuf() call below.
 1324                  */
 1325                 if (intrflg && (error = newnfs_sigintr(nmp, td)))
 1326                         goto out;
 1327         }
 1328 
 1329         error = vinvalbuf(vp, flags, slpflag, 0);
 1330         while (error) {
 1331                 if (intrflg && (error = newnfs_sigintr(nmp, td)))
 1332                         goto out;
 1333                 error = vinvalbuf(vp, flags, 0, slptimeo);
 1334         }
 1335         mtx_lock(&np->n_mtx);
 1336         if (np->n_directio_asyncwr == 0)
 1337                 np->n_flag &= ~NMODIFIED;
 1338         mtx_unlock(&np->n_mtx);
 1339 out:
 1340         ncl_downgrade_vnlock(vp, old_lock);
 1341         return error;
 1342 }
 1343 
 1344 /*
 1345  * Initiate asynchronous I/O. Return an error if no nfsiods are available.
 1346  * This is mainly to avoid queueing async I/O requests when the nfsiods
 1347  * are all hung on a dead server.
 1348  *
 1349  * Note: ncl_asyncio() does not clear (BIO_ERROR|B_INVAL) but when the bp
 1350  * is eventually dequeued by the async daemon, ncl_doio() *will*.
 1351  */
 1352 int
 1353 ncl_asyncio(struct nfsmount *nmp, struct buf *bp, struct ucred *cred, struct thread *td)
 1354 {
 1355         int iod;
 1356         int gotiod;
 1357         int slpflag = 0;
 1358         int slptimeo = 0;
 1359         int error, error2;
 1360 
 1361         /*
 1362          * Commits are usually short and sweet so lets save some cpu and
 1363          * leave the async daemons for more important rpc's (such as reads
 1364          * and writes).
 1365          */
 1366         mtx_lock(&ncl_iod_mutex);
 1367         if (bp->b_iocmd == BIO_WRITE && (bp->b_flags & B_NEEDCOMMIT) &&
 1368             (nmp->nm_bufqiods > ncl_numasync / 2)) {
 1369                 mtx_unlock(&ncl_iod_mutex);
 1370                 return(EIO);
 1371         }
 1372 again:
 1373         if (nmp->nm_flag & NFSMNT_INT)
 1374                 slpflag = NFS_PCATCH;
 1375         gotiod = FALSE;
 1376 
 1377         /*
 1378          * Find a free iod to process this request.
 1379          */
 1380         for (iod = 0; iod < ncl_numasync; iod++)
 1381                 if (ncl_iodwant[iod] == NFSIOD_AVAILABLE) {
 1382                         gotiod = TRUE;
 1383                         break;
 1384                 }
 1385 
 1386         /*
 1387          * Try to create one if none are free.
 1388          */
 1389         if (!gotiod)
 1390                 ncl_nfsiodnew();
 1391         else {
 1392                 /*
 1393                  * Found one, so wake it up and tell it which
 1394                  * mount to process.
 1395                  */
 1396                 NFS_DPF(ASYNCIO, ("ncl_asyncio: waking iod %d for mount %p\n",
 1397                     iod, nmp));
 1398                 ncl_iodwant[iod] = NFSIOD_NOT_AVAILABLE;
 1399                 ncl_iodmount[iod] = nmp;
 1400                 nmp->nm_bufqiods++;
 1401                 wakeup(&ncl_iodwant[iod]);
 1402         }
 1403 
 1404         /*
 1405          * If none are free, we may already have an iod working on this mount
 1406          * point.  If so, it will process our request.
 1407          */
 1408         if (!gotiod) {
 1409                 if (nmp->nm_bufqiods > 0) {
 1410                         NFS_DPF(ASYNCIO,
 1411                                 ("ncl_asyncio: %d iods are already processing mount %p\n",
 1412                                  nmp->nm_bufqiods, nmp));
 1413                         gotiod = TRUE;
 1414                 }
 1415         }
 1416 
 1417         /*
 1418          * If we have an iod which can process the request, then queue
 1419          * the buffer.
 1420          */
 1421         if (gotiod) {
 1422                 /*
 1423                  * Ensure that the queue never grows too large.  We still want
 1424                  * to asynchronize so we block rather then return EIO.
 1425                  */
 1426                 while (nmp->nm_bufqlen >= 2*ncl_numasync) {
 1427                         NFS_DPF(ASYNCIO,
 1428                                 ("ncl_asyncio: waiting for mount %p queue to drain\n", nmp));
 1429                         nmp->nm_bufqwant = TRUE;
 1430                         error = newnfs_msleep(td, &nmp->nm_bufq, 
 1431                             &ncl_iod_mutex, slpflag | PRIBIO, "nfsaio",
 1432                            slptimeo);
 1433                         if (error) {
 1434                                 error2 = newnfs_sigintr(nmp, td);
 1435                                 if (error2) {
 1436                                         mtx_unlock(&ncl_iod_mutex);                                     
 1437                                         return (error2);
 1438                                 }
 1439                                 if (slpflag == NFS_PCATCH) {
 1440                                         slpflag = 0;
 1441                                         slptimeo = 2 * hz;
 1442                                 }
 1443                         }
 1444                         /*
 1445                          * We might have lost our iod while sleeping,
 1446                          * so check and loop if nescessary.
 1447                          */
 1448                         goto again;
 1449                 }
 1450 
 1451                 /* We might have lost our nfsiod */
 1452                 if (nmp->nm_bufqiods == 0) {
 1453                         NFS_DPF(ASYNCIO,
 1454                                 ("ncl_asyncio: no iods after mount %p queue was drained, looping\n", nmp));
 1455                         goto again;
 1456                 }
 1457 
 1458                 if (bp->b_iocmd == BIO_READ) {
 1459                         if (bp->b_rcred == NOCRED && cred != NOCRED)
 1460                                 bp->b_rcred = crhold(cred);
 1461                 } else {
 1462                         if (bp->b_wcred == NOCRED && cred != NOCRED)
 1463                                 bp->b_wcred = crhold(cred);
 1464                 }
 1465 
 1466                 if (bp->b_flags & B_REMFREE)
 1467                         bremfreef(bp);
 1468                 BUF_KERNPROC(bp);
 1469                 TAILQ_INSERT_TAIL(&nmp->nm_bufq, bp, b_freelist);
 1470                 nmp->nm_bufqlen++;
 1471                 if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1472                         mtx_lock(&(VTONFS(bp->b_vp))->n_mtx);                   
 1473                         VTONFS(bp->b_vp)->n_flag |= NMODIFIED;
 1474                         VTONFS(bp->b_vp)->n_directio_asyncwr++;
 1475                         mtx_unlock(&(VTONFS(bp->b_vp))->n_mtx);
 1476                 }
 1477                 mtx_unlock(&ncl_iod_mutex);
 1478                 return (0);
 1479         }
 1480 
 1481         mtx_unlock(&ncl_iod_mutex);
 1482 
 1483         /*
 1484          * All the iods are busy on other mounts, so return EIO to
 1485          * force the caller to process the i/o synchronously.
 1486          */
 1487         NFS_DPF(ASYNCIO, ("ncl_asyncio: no iods available, i/o is synchronous\n"));
 1488         return (EIO);
 1489 }
 1490 
 1491 void
 1492 ncl_doio_directwrite(struct buf *bp)
 1493 {
 1494         int iomode, must_commit;
 1495         struct uio *uiop = (struct uio *)bp->b_caller1;
 1496         char *iov_base = uiop->uio_iov->iov_base;
 1497         
 1498         iomode = NFSWRITE_FILESYNC;
 1499         uiop->uio_td = NULL; /* NULL since we're in nfsiod */
 1500         ncl_writerpc(bp->b_vp, uiop, bp->b_wcred, &iomode, &must_commit, 0);
 1501         KASSERT((must_commit == 0), ("ncl_doio_directwrite: Did not commit write"));
 1502         free(iov_base, M_NFSDIRECTIO);
 1503         free(uiop->uio_iov, M_NFSDIRECTIO);
 1504         free(uiop, M_NFSDIRECTIO);
 1505         if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1506                 struct nfsnode *np = VTONFS(bp->b_vp);
 1507                 mtx_lock(&np->n_mtx);
 1508                 np->n_directio_asyncwr--;
 1509                 if (np->n_directio_asyncwr == 0) {
 1510                         np->n_flag &= ~NMODIFIED;
 1511                         if ((np->n_flag & NFSYNCWAIT)) {
 1512                                 np->n_flag &= ~NFSYNCWAIT;
 1513                                 wakeup((caddr_t)&np->n_directio_asyncwr);
 1514                         }
 1515                 }
 1516                 mtx_unlock(&np->n_mtx);
 1517         }
 1518         bp->b_vp = NULL;
 1519         relpbuf(bp, &ncl_pbuf_freecnt);
 1520 }
 1521 
 1522 /*
 1523  * Do an I/O operation to/from a cache block. This may be called
 1524  * synchronously or from an nfsiod.
 1525  */
 1526 int
 1527 ncl_doio(struct vnode *vp, struct buf *bp, struct ucred *cr, struct thread *td,
 1528     int called_from_strategy)
 1529 {
 1530         struct uio *uiop;
 1531         struct nfsnode *np;
 1532         struct nfsmount *nmp;
 1533         int error = 0, iomode, must_commit = 0;
 1534         struct uio uio;
 1535         struct iovec io;
 1536         struct proc *p = td ? td->td_proc : NULL;
 1537         uint8_t iocmd;
 1538         
 1539         np = VTONFS(vp);
 1540         nmp = VFSTONFS(vp->v_mount);
 1541         uiop = &uio;
 1542         uiop->uio_iov = &io;
 1543         uiop->uio_iovcnt = 1;
 1544         uiop->uio_segflg = UIO_SYSSPACE;
 1545         uiop->uio_td = td;
 1546 
 1547         /*
 1548          * clear BIO_ERROR and B_INVAL state prior to initiating the I/O.  We
 1549          * do this here so we do not have to do it in all the code that
 1550          * calls us.
 1551          */
 1552         bp->b_flags &= ~B_INVAL;
 1553         bp->b_ioflags &= ~BIO_ERROR;
 1554 
 1555         KASSERT(!(bp->b_flags & B_DONE), ("ncl_doio: bp %p already marked done", bp));
 1556         iocmd = bp->b_iocmd;
 1557         if (iocmd == BIO_READ) {
 1558             io.iov_len = uiop->uio_resid = bp->b_bcount;
 1559             io.iov_base = bp->b_data;
 1560             uiop->uio_rw = UIO_READ;
 1561 
 1562             switch (vp->v_type) {
 1563             case VREG:
 1564                 uiop->uio_offset = ((off_t)bp->b_blkno) * DEV_BSIZE;
 1565                 NFSINCRGLOBAL(newnfsstats.read_bios);
 1566                 error = ncl_readrpc(vp, uiop, cr);
 1567 
 1568                 if (!error) {
 1569                     if (uiop->uio_resid) {
 1570                         /*
 1571                          * If we had a short read with no error, we must have
 1572                          * hit a file hole.  We should zero-fill the remainder.
 1573                          * This can also occur if the server hits the file EOF.
 1574                          *
 1575                          * Holes used to be able to occur due to pending
 1576                          * writes, but that is not possible any longer.
 1577                          */
 1578                         int nread = bp->b_bcount - uiop->uio_resid;
 1579                         int left  = uiop->uio_resid;
 1580 
 1581                         if (left > 0)
 1582                                 bzero((char *)bp->b_data + nread, left);
 1583                         uiop->uio_resid = 0;
 1584                     }
 1585                 }
 1586                 /* ASSERT_VOP_LOCKED(vp, "ncl_doio"); */
 1587                 if (p && (vp->v_vflag & VV_TEXT)) {
 1588                         mtx_lock(&np->n_mtx);
 1589                         if (NFS_TIMESPEC_COMPARE(&np->n_mtime, &np->n_vattr.na_mtime)) {
 1590                                 mtx_unlock(&np->n_mtx);
 1591                                 PROC_LOCK(p);
 1592                                 killproc(p, "text file modification");
 1593                                 PROC_UNLOCK(p);
 1594                         } else
 1595                                 mtx_unlock(&np->n_mtx);
 1596                 }
 1597                 break;
 1598             case VLNK:
 1599                 uiop->uio_offset = (off_t)0;
 1600                 NFSINCRGLOBAL(newnfsstats.readlink_bios);
 1601                 error = ncl_readlinkrpc(vp, uiop, cr);
 1602                 break;
 1603             case VDIR:
 1604                 NFSINCRGLOBAL(newnfsstats.readdir_bios);
 1605                 uiop->uio_offset = ((u_quad_t)bp->b_lblkno) * NFS_DIRBLKSIZ;
 1606                 if ((nmp->nm_flag & NFSMNT_RDIRPLUS) != 0) {
 1607                         error = ncl_readdirplusrpc(vp, uiop, cr, td);
 1608                         if (error == NFSERR_NOTSUPP)
 1609                                 nmp->nm_flag &= ~NFSMNT_RDIRPLUS;
 1610                 }
 1611                 if ((nmp->nm_flag & NFSMNT_RDIRPLUS) == 0)
 1612                         error = ncl_readdirrpc(vp, uiop, cr, td);
 1613                 /*
 1614                  * end-of-directory sets B_INVAL but does not generate an
 1615                  * error.
 1616                  */
 1617                 if (error == 0 && uiop->uio_resid == bp->b_bcount)
 1618                         bp->b_flags |= B_INVAL;
 1619                 break;
 1620             default:
 1621                 ncl_printf("ncl_doio:  type %x unexpected\n", vp->v_type);
 1622                 break;
 1623             };
 1624             if (error) {
 1625                 bp->b_ioflags |= BIO_ERROR;
 1626                 bp->b_error = error;
 1627             }
 1628         } else {
 1629             /*
 1630              * If we only need to commit, try to commit
 1631              */
 1632             if (bp->b_flags & B_NEEDCOMMIT) {
 1633                     int retv;
 1634                     off_t off;
 1635 
 1636                     off = ((u_quad_t)bp->b_blkno) * DEV_BSIZE + bp->b_dirtyoff;
 1637                     retv = ncl_commit(vp, off, bp->b_dirtyend-bp->b_dirtyoff,
 1638                         bp->b_wcred, td);
 1639                     if (retv == 0) {
 1640                             bp->b_dirtyoff = bp->b_dirtyend = 0;
 1641                             bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1642                             bp->b_resid = 0;
 1643                             bufdone(bp);
 1644                             return (0);
 1645                     }
 1646                     if (retv == NFSERR_STALEWRITEVERF) {
 1647                             ncl_clearcommit(vp->v_mount);
 1648                     }
 1649             }
 1650 
 1651             /*
 1652              * Setup for actual write
 1653              */
 1654             mtx_lock(&np->n_mtx);
 1655             if ((off_t)bp->b_blkno * DEV_BSIZE + bp->b_dirtyend > np->n_size)
 1656                 bp->b_dirtyend = np->n_size - (off_t)bp->b_blkno * DEV_BSIZE;
 1657             mtx_unlock(&np->n_mtx);
 1658 
 1659             if (bp->b_dirtyend > bp->b_dirtyoff) {
 1660                 io.iov_len = uiop->uio_resid = bp->b_dirtyend
 1661                     - bp->b_dirtyoff;
 1662                 uiop->uio_offset = (off_t)bp->b_blkno * DEV_BSIZE
 1663                     + bp->b_dirtyoff;
 1664                 io.iov_base = (char *)bp->b_data + bp->b_dirtyoff;
 1665                 uiop->uio_rw = UIO_WRITE;
 1666                 NFSINCRGLOBAL(newnfsstats.write_bios);
 1667 
 1668                 if ((bp->b_flags & (B_ASYNC | B_NEEDCOMMIT | B_NOCACHE | B_CLUSTER)) == B_ASYNC)
 1669                     iomode = NFSWRITE_UNSTABLE;
 1670                 else
 1671                     iomode = NFSWRITE_FILESYNC;
 1672 
 1673                 error = ncl_writerpc(vp, uiop, cr, &iomode, &must_commit,
 1674                     called_from_strategy);
 1675 
 1676                 /*
 1677                  * When setting B_NEEDCOMMIT also set B_CLUSTEROK to try
 1678                  * to cluster the buffers needing commit.  This will allow
 1679                  * the system to submit a single commit rpc for the whole
 1680                  * cluster.  We can do this even if the buffer is not 100%
 1681                  * dirty (relative to the NFS blocksize), so we optimize the
 1682                  * append-to-file-case.
 1683                  *
 1684                  * (when clearing B_NEEDCOMMIT, B_CLUSTEROK must also be
 1685                  * cleared because write clustering only works for commit
 1686                  * rpc's, not for the data portion of the write).
 1687                  */
 1688 
 1689                 if (!error && iomode == NFSWRITE_UNSTABLE) {
 1690                     bp->b_flags |= B_NEEDCOMMIT;
 1691                     if (bp->b_dirtyoff == 0
 1692                         && bp->b_dirtyend == bp->b_bcount)
 1693                         bp->b_flags |= B_CLUSTEROK;
 1694                 } else {
 1695                     bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1696                 }
 1697 
 1698                 /*
 1699                  * For an interrupted write, the buffer is still valid
 1700                  * and the write hasn't been pushed to the server yet,
 1701                  * so we can't set BIO_ERROR and report the interruption
 1702                  * by setting B_EINTR. For the B_ASYNC case, B_EINTR
 1703                  * is not relevant, so the rpc attempt is essentially
 1704                  * a noop.  For the case of a V3 write rpc not being
 1705                  * committed to stable storage, the block is still
 1706                  * dirty and requires either a commit rpc or another
 1707                  * write rpc with iomode == NFSV3WRITE_FILESYNC before
 1708                  * the block is reused. This is indicated by setting
 1709                  * the B_DELWRI and B_NEEDCOMMIT flags.
 1710                  *
 1711                  * EIO is returned by ncl_writerpc() to indicate a recoverable
 1712                  * write error and is handled as above, except that
 1713                  * B_EINTR isn't set. One cause of this is a stale stateid
 1714                  * error for the RPC that indicates recovery is required,
 1715                  * when called with called_from_strategy != 0.
 1716                  *
 1717                  * If the buffer is marked B_PAGING, it does not reside on
 1718                  * the vp's paging queues so we cannot call bdirty().  The
 1719                  * bp in this case is not an NFS cache block so we should
 1720                  * be safe. XXX
 1721                  *
 1722                  * The logic below breaks up errors into recoverable and 
 1723                  * unrecoverable. For the former, we clear B_INVAL|B_NOCACHE
 1724                  * and keep the buffer around for potential write retries.
 1725                  * For the latter (eg ESTALE), we toss the buffer away (B_INVAL)
 1726                  * and save the error in the nfsnode. This is less than ideal 
 1727                  * but necessary. Keeping such buffers around could potentially
 1728                  * cause buffer exhaustion eventually (they can never be written
 1729                  * out, so will get constantly be re-dirtied). It also causes
 1730                  * all sorts of vfs panics. For non-recoverable write errors, 
 1731                  * also invalidate the attrcache, so we'll be forced to go over
 1732                  * the wire for this object, returning an error to user on next
 1733                  * call (most of the time).
 1734                  */
 1735                 if (error == EINTR || error == EIO || error == ETIMEDOUT
 1736                     || (!error && (bp->b_flags & B_NEEDCOMMIT))) {
 1737                         int s;
 1738 
 1739                         s = splbio();
 1740                         bp->b_flags &= ~(B_INVAL|B_NOCACHE);
 1741                         if ((bp->b_flags & B_PAGING) == 0) {
 1742                             bdirty(bp);
 1743                             bp->b_flags &= ~B_DONE;
 1744                         }
 1745                         if ((error == EINTR || error == ETIMEDOUT) &&
 1746                             (bp->b_flags & B_ASYNC) == 0)
 1747                             bp->b_flags |= B_EINTR;
 1748                         splx(s);
 1749                 } else {
 1750                     if (error) {
 1751                         bp->b_ioflags |= BIO_ERROR;
 1752                         bp->b_flags |= B_INVAL;
 1753                         bp->b_error = np->n_error = error;
 1754                         mtx_lock(&np->n_mtx);
 1755                         np->n_flag |= NWRITEERR;
 1756                         np->n_attrstamp = 0;
 1757                         KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
 1758                         mtx_unlock(&np->n_mtx);
 1759                     }
 1760                     bp->b_dirtyoff = bp->b_dirtyend = 0;
 1761                 }
 1762             } else {
 1763                 bp->b_resid = 0;
 1764                 bufdone(bp);
 1765                 return (0);
 1766             }
 1767         }
 1768         bp->b_resid = uiop->uio_resid;
 1769         if (must_commit)
 1770             ncl_clearcommit(vp->v_mount);
 1771         bufdone(bp);
 1772         return (error);
 1773 }
 1774 
 1775 /*
 1776  * Used to aid in handling ftruncate() operations on the NFS client side.
 1777  * Truncation creates a number of special problems for NFS.  We have to
 1778  * throw away VM pages and buffer cache buffers that are beyond EOF, and
 1779  * we have to properly handle VM pages or (potentially dirty) buffers
 1780  * that straddle the truncation point.
 1781  */
 1782 
 1783 int
 1784 ncl_meta_setsize(struct vnode *vp, struct ucred *cred, struct thread *td, u_quad_t nsize)
 1785 {
 1786         struct nfsnode *np = VTONFS(vp);
 1787         u_quad_t tsize;
 1788         int biosize = vp->v_mount->mnt_stat.f_iosize;
 1789         int error = 0;
 1790 
 1791         mtx_lock(&np->n_mtx);
 1792         tsize = np->n_size;
 1793         np->n_size = nsize;
 1794         mtx_unlock(&np->n_mtx);
 1795 
 1796         if (nsize < tsize) {
 1797                 struct buf *bp;
 1798                 daddr_t lbn;
 1799                 int bufsize;
 1800 
 1801                 /*
 1802                  * vtruncbuf() doesn't get the buffer overlapping the 
 1803                  * truncation point.  We may have a B_DELWRI and/or B_CACHE
 1804                  * buffer that now needs to be truncated.
 1805                  */
 1806                 error = vtruncbuf(vp, cred, td, nsize, biosize);
 1807                 lbn = nsize / biosize;
 1808                 bufsize = nsize & (biosize - 1);
 1809                 bp = nfs_getcacheblk(vp, lbn, bufsize, td);
 1810                 if (!bp)
 1811                         return EINTR;
 1812                 if (bp->b_dirtyoff > bp->b_bcount)
 1813                         bp->b_dirtyoff = bp->b_bcount;
 1814                 if (bp->b_dirtyend > bp->b_bcount)
 1815                         bp->b_dirtyend = bp->b_bcount;
 1816                 bp->b_flags |= B_RELBUF;  /* don't leave garbage around */
 1817                 brelse(bp);
 1818         } else {
 1819                 vnode_pager_setsize(vp, nsize);
 1820         }
 1821         return(error);
 1822 }
 1823 

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