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/8.0/sys/fs/nfsclient/nfs_clbio.c 195821 2009-07-22 14:37:53Z rmacklem $");
   37 
   38 #include <sys/param.h>
   39 #include <sys/systm.h>
   40 #include <sys/bio.h>
   41 #include <sys/buf.h>
   42 #include <sys/kernel.h>
   43 #include <sys/mount.h>
   44 #include <sys/proc.h>
   45 #include <sys/resourcevar.h>
   46 #include <sys/signalvar.h>
   47 #include <sys/vmmeter.h>
   48 #include <sys/vnode.h>
   49 
   50 #include <vm/vm.h>
   51 #include <vm/vm_extern.h>
   52 #include <vm/vm_page.h>
   53 #include <vm/vm_object.h>
   54 #include <vm/vm_pager.h>
   55 #include <vm/vnode_pager.h>
   56 
   57 #include <fs/nfs/nfsport.h>
   58 #include <fs/nfsclient/nfsmount.h>
   59 #include <fs/nfsclient/nfs.h>
   60 #include <fs/nfsclient/nfsnode.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 struct proc *ncl_iodwant[NFS_MAXRAHEAD];
   67 extern struct nfsmount *ncl_iodmount[NFS_MAXRAHEAD];
   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  * Any signal that can interrupt an NFS operation in an intr mount
   79  * should be added to this set. SIGSTOP and SIGKILL cannot be masked.
   80  */
   81 static int nfs_sig_set[] = {
   82         SIGINT,
   83         SIGTERM,
   84         SIGHUP,
   85         SIGKILL,
   86         SIGSTOP,
   87         SIGQUIT
   88 };
   89 
   90 #ifdef notnow
   91 /*
   92  * Check to see if one of the signals in our subset is pending on
   93  * the process (in an intr mount).
   94  */
   95 int
   96 ncl_sig_pending(sigset_t set)
   97 {
   98         int i;
   99         
  100         for (i = 0 ; i < sizeof(nfs_sig_set)/sizeof(int) ; i++)
  101                 if (SIGISMEMBER(set, nfs_sig_set[i]))
  102                         return (1);
  103         return (0);
  104 }
  105 #endif
  106  
  107 /*
  108  * The set/restore sigmask functions are used to (temporarily) overwrite
  109  * the process p_sigmask during an RPC call (for example). These are also
  110  * used in other places in the NFS client that might tsleep().
  111  */
  112 static void
  113 ncl_set_sigmask(struct thread *td, sigset_t *oldset)
  114 {
  115         sigset_t newset;
  116         int i;
  117         struct proc *p;
  118         
  119         SIGFILLSET(newset);
  120         if (td == NULL)
  121                 td = curthread; /* XXX */
  122         p = td->td_proc;
  123         /* Remove the NFS set of signals from newset */
  124         PROC_LOCK(p);
  125         mtx_lock(&p->p_sigacts->ps_mtx);
  126         for (i = 0 ; i < sizeof(nfs_sig_set)/sizeof(int) ; i++) {
  127                 /*
  128                  * But make sure we leave the ones already masked
  129                  * by the process, ie. remove the signal from the
  130                  * temporary signalmask only if it wasn't already
  131                  * in p_sigmask.
  132                  */
  133                 if (!SIGISMEMBER(td->td_sigmask, nfs_sig_set[i]) &&
  134                     !SIGISMEMBER(p->p_sigacts->ps_sigignore, nfs_sig_set[i]))
  135                         SIGDELSET(newset, nfs_sig_set[i]);
  136         }
  137         mtx_unlock(&p->p_sigacts->ps_mtx);
  138         PROC_UNLOCK(p);
  139         kern_sigprocmask(td, SIG_SETMASK, &newset, oldset, 0);
  140 }
  141 
  142 static void
  143 ncl_restore_sigmask(struct thread *td, sigset_t *set)
  144 {
  145         if (td == NULL)
  146                 td = curthread; /* XXX */
  147         kern_sigprocmask(td, SIG_SETMASK, set, NULL, 0);
  148 }
  149 
  150 /*
  151  * NFS wrapper to msleep(), that shoves a new p_sigmask and restores the
  152  * old one after msleep() returns.
  153  */
  154 int
  155 ncl_msleep(struct thread *td, void *ident, struct mtx *mtx, int priority, char *wmesg, int timo)
  156 {
  157         sigset_t oldset;
  158         int error;
  159         struct proc *p;
  160         
  161         if ((priority & PCATCH) == 0)
  162                 return msleep(ident, mtx, priority, wmesg, timo);
  163         if (td == NULL)
  164                 td = curthread; /* XXX */
  165         ncl_set_sigmask(td, &oldset);
  166         error = msleep(ident, mtx, priority, wmesg, timo);
  167         ncl_restore_sigmask(td, &oldset);
  168         p = td->td_proc;
  169         return (error);
  170 }
  171 
  172 /*
  173  * Vnode op for VM getpages.
  174  */
  175 int
  176 ncl_getpages(struct vop_getpages_args *ap)
  177 {
  178         int i, error, nextoff, size, toff, count, npages;
  179         struct uio uio;
  180         struct iovec iov;
  181         vm_offset_t kva;
  182         struct buf *bp;
  183         struct vnode *vp;
  184         struct thread *td;
  185         struct ucred *cred;
  186         struct nfsmount *nmp;
  187         vm_object_t object;
  188         vm_page_t *pages;
  189         struct nfsnode *np;
  190 
  191         vp = ap->a_vp;
  192         np = VTONFS(vp);
  193         td = curthread;                         /* XXX */
  194         cred = curthread->td_ucred;             /* XXX */
  195         nmp = VFSTONFS(vp->v_mount);
  196         pages = ap->a_m;
  197         count = ap->a_count;
  198 
  199         if ((object = vp->v_object) == NULL) {
  200                 ncl_printf("nfs_getpages: called with non-merged cache vnode??\n");
  201                 return (VM_PAGER_ERROR);
  202         }
  203 
  204         if (newnfs_directio_enable && !newnfs_directio_allow_mmap) {
  205                 mtx_lock(&np->n_mtx);
  206                 if ((np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
  207                         mtx_unlock(&np->n_mtx);
  208                         ncl_printf("nfs_getpages: called on non-cacheable vnode??\n");
  209                         return (VM_PAGER_ERROR);
  210                 } else
  211                         mtx_unlock(&np->n_mtx);
  212         }
  213 
  214         mtx_lock(&nmp->nm_mtx);
  215         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  216             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {  
  217                 mtx_unlock(&nmp->nm_mtx);
  218                 /* We'll never get here for v4, because we always have fsinfo */
  219                 (void)ncl_fsinfo(nmp, vp, cred, td);
  220         } else
  221                 mtx_unlock(&nmp->nm_mtx);
  222 
  223         npages = btoc(count);
  224 
  225         /*
  226          * If the requested page is partially valid, just return it and
  227          * allow the pager to zero-out the blanks.  Partially valid pages
  228          * can only occur at the file EOF.
  229          */
  230         VM_OBJECT_LOCK(object);
  231         if (pages[ap->a_reqpage]->valid != 0) {
  232                 vm_page_lock_queues();
  233                 for (i = 0; i < npages; ++i) {
  234                         if (i != ap->a_reqpage)
  235                                 vm_page_free(pages[i]);
  236                 }
  237                 vm_page_unlock_queues();
  238                 VM_OBJECT_UNLOCK(object);
  239                 return (0);
  240         }
  241         VM_OBJECT_UNLOCK(object);
  242 
  243         /*
  244          * We use only the kva address for the buffer, but this is extremely
  245          * convienient and fast.
  246          */
  247         bp = getpbuf(&ncl_pbuf_freecnt);
  248 
  249         kva = (vm_offset_t) bp->b_data;
  250         pmap_qenter(kva, pages, npages);
  251         PCPU_INC(cnt.v_vnodein);
  252         PCPU_ADD(cnt.v_vnodepgsin, npages);
  253 
  254         iov.iov_base = (caddr_t) kva;
  255         iov.iov_len = count;
  256         uio.uio_iov = &iov;
  257         uio.uio_iovcnt = 1;
  258         uio.uio_offset = IDX_TO_OFF(pages[0]->pindex);
  259         uio.uio_resid = count;
  260         uio.uio_segflg = UIO_SYSSPACE;
  261         uio.uio_rw = UIO_READ;
  262         uio.uio_td = td;
  263 
  264         error = ncl_readrpc(vp, &uio, cred);
  265         pmap_qremove(kva, npages);
  266 
  267         relpbuf(bp, &ncl_pbuf_freecnt);
  268 
  269         if (error && (uio.uio_resid == count)) {
  270                 ncl_printf("nfs_getpages: error %d\n", error);
  271                 VM_OBJECT_LOCK(object);
  272                 vm_page_lock_queues();
  273                 for (i = 0; i < npages; ++i) {
  274                         if (i != ap->a_reqpage)
  275                                 vm_page_free(pages[i]);
  276                 }
  277                 vm_page_unlock_queues();
  278                 VM_OBJECT_UNLOCK(object);
  279                 return (VM_PAGER_ERROR);
  280         }
  281 
  282         /*
  283          * Calculate the number of bytes read and validate only that number
  284          * of bytes.  Note that due to pending writes, size may be 0.  This
  285          * does not mean that the remaining data is invalid!
  286          */
  287 
  288         size = count - uio.uio_resid;
  289         VM_OBJECT_LOCK(object);
  290         vm_page_lock_queues();
  291         for (i = 0, toff = 0; i < npages; i++, toff = nextoff) {
  292                 vm_page_t m;
  293                 nextoff = toff + PAGE_SIZE;
  294                 m = pages[i];
  295 
  296                 if (nextoff <= size) {
  297                         /*
  298                          * Read operation filled an entire page
  299                          */
  300                         m->valid = VM_PAGE_BITS_ALL;
  301                         KASSERT(m->dirty == 0,
  302                             ("nfs_getpages: page %p is dirty", m));
  303                 } else if (size > toff) {
  304                         /*
  305                          * Read operation filled a partial page.
  306                          */
  307                         m->valid = 0;
  308                         vm_page_set_valid(m, 0, size - toff);
  309                         KASSERT(m->dirty == 0,
  310                             ("nfs_getpages: page %p is dirty", m));
  311                 } else {
  312                         /*
  313                          * Read operation was short.  If no error occured
  314                          * we may have hit a zero-fill section.   We simply
  315                          * leave valid set to 0.
  316                          */
  317                         ;
  318                 }
  319                 if (i != ap->a_reqpage) {
  320                         /*
  321                          * Whether or not to leave the page activated is up in
  322                          * the air, but we should put the page on a page queue
  323                          * somewhere (it already is in the object).  Result:
  324                          * It appears that emperical results show that
  325                          * deactivating pages is best.
  326                          */
  327 
  328                         /*
  329                          * Just in case someone was asking for this page we
  330                          * now tell them that it is ok to use.
  331                          */
  332                         if (!error) {
  333                                 if (m->oflags & VPO_WANTED)
  334                                         vm_page_activate(m);
  335                                 else
  336                                         vm_page_deactivate(m);
  337                                 vm_page_wakeup(m);
  338                         } else {
  339                                 vm_page_free(m);
  340                         }
  341                 }
  342         }
  343         vm_page_unlock_queues();
  344         VM_OBJECT_UNLOCK(object);
  345         return (0);
  346 }
  347 
  348 /*
  349  * Vnode op for VM putpages.
  350  */
  351 int
  352 ncl_putpages(struct vop_putpages_args *ap)
  353 {
  354         struct uio uio;
  355         struct iovec iov;
  356         vm_offset_t kva;
  357         struct buf *bp;
  358         int iomode, must_commit, i, error, npages, count;
  359         off_t offset;
  360         int *rtvals;
  361         struct vnode *vp;
  362         struct thread *td;
  363         struct ucred *cred;
  364         struct nfsmount *nmp;
  365         struct nfsnode *np;
  366         vm_page_t *pages;
  367 
  368         vp = ap->a_vp;
  369         np = VTONFS(vp);
  370         td = curthread;                         /* XXX */
  371         cred = curthread->td_ucred;             /* XXX */
  372         nmp = VFSTONFS(vp->v_mount);
  373         pages = ap->a_m;
  374         count = ap->a_count;
  375         rtvals = ap->a_rtvals;
  376         npages = btoc(count);
  377         offset = IDX_TO_OFF(pages[0]->pindex);
  378         
  379         mtx_lock(&nmp->nm_mtx);
  380         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  381             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  382                 mtx_unlock(&nmp->nm_mtx);
  383                 (void)ncl_fsinfo(nmp, vp, cred, td);
  384         } else
  385                 mtx_unlock(&nmp->nm_mtx);
  386 
  387         mtx_lock(&np->n_mtx);
  388         if (newnfs_directio_enable && !newnfs_directio_allow_mmap && 
  389             (np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
  390                 mtx_unlock(&np->n_mtx);         
  391                 ncl_printf("ncl_putpages: called on noncache-able vnode??\n");
  392                 mtx_lock(&np->n_mtx);
  393         }
  394 
  395         for (i = 0; i < npages; i++)
  396                 rtvals[i] = VM_PAGER_AGAIN;
  397 
  398         /*
  399          * When putting pages, do not extend file past EOF.
  400          */
  401         if (offset + count > np->n_size) {
  402                 count = np->n_size - offset;
  403                 if (count < 0)
  404                         count = 0;
  405         }
  406         mtx_unlock(&np->n_mtx);
  407 
  408         /*
  409          * We use only the kva address for the buffer, but this is extremely
  410          * convienient and fast.
  411          */
  412         bp = getpbuf(&ncl_pbuf_freecnt);
  413 
  414         kva = (vm_offset_t) bp->b_data;
  415         pmap_qenter(kva, pages, npages);
  416         PCPU_INC(cnt.v_vnodeout);
  417         PCPU_ADD(cnt.v_vnodepgsout, count);
  418 
  419         iov.iov_base = (caddr_t) kva;
  420         iov.iov_len = count;
  421         uio.uio_iov = &iov;
  422         uio.uio_iovcnt = 1;
  423         uio.uio_offset = offset;
  424         uio.uio_resid = count;
  425         uio.uio_segflg = UIO_SYSSPACE;
  426         uio.uio_rw = UIO_WRITE;
  427         uio.uio_td = td;
  428 
  429         if ((ap->a_sync & VM_PAGER_PUT_SYNC) == 0)
  430             iomode = NFSWRITE_UNSTABLE;
  431         else
  432             iomode = NFSWRITE_FILESYNC;
  433 
  434         error = ncl_writerpc(vp, &uio, cred, &iomode, &must_commit);
  435 
  436         pmap_qremove(kva, npages);
  437         relpbuf(bp, &ncl_pbuf_freecnt);
  438 
  439         if (!error) {
  440                 int nwritten = round_page(count - uio.uio_resid) / PAGE_SIZE;
  441                 for (i = 0; i < nwritten; i++) {
  442                         rtvals[i] = VM_PAGER_OK;
  443                         vm_page_undirty(pages[i]);
  444                 }
  445                 if (must_commit) {
  446                         ncl_clearcommit(vp->v_mount);
  447                 }
  448         }
  449         return rtvals[0];
  450 }
  451 
  452 /*
  453  * For nfs, cache consistency can only be maintained approximately.
  454  * Although RFC1094 does not specify the criteria, the following is
  455  * believed to be compatible with the reference port.
  456  * For nfs:
  457  * If the file's modify time on the server has changed since the
  458  * last read rpc or you have written to the file,
  459  * you may have lost data cache consistency with the
  460  * server, so flush all of the file's data out of the cache.
  461  * Then force a getattr rpc to ensure that you have up to date
  462  * attributes.
  463  * NB: This implies that cache data can be read when up to
  464  * NFS_ATTRTIMEO seconds out of date. If you find that you need current
  465  * attributes this could be forced by setting n_attrstamp to 0 before
  466  * the VOP_GETATTR() call.
  467  */
  468 static inline int
  469 nfs_bioread_check_cons(struct vnode *vp, struct thread *td, struct ucred *cred)
  470 {
  471         int error = 0;
  472         struct vattr vattr;
  473         struct nfsnode *np = VTONFS(vp);
  474         int old_lock;
  475         
  476         /*
  477          * Grab the exclusive lock before checking whether the cache is
  478          * consistent.
  479          * XXX - We can make this cheaper later (by acquiring cheaper locks).
  480          * But for now, this suffices.
  481          */
  482         old_lock = ncl_upgrade_vnlock(vp);
  483         if (vp->v_iflag & VI_DOOMED) {
  484                 ncl_downgrade_vnlock(vp, old_lock);
  485                 return (EBADF);
  486         }
  487 
  488         mtx_lock(&np->n_mtx);
  489         if (np->n_flag & NMODIFIED) {
  490                 mtx_unlock(&np->n_mtx);
  491                 if (vp->v_type != VREG) {
  492                         if (vp->v_type != VDIR)
  493                                 panic("nfs: bioread, not dir");
  494                         ncl_invaldir(vp);
  495                         error = ncl_vinvalbuf(vp, V_SAVE, td, 1);
  496                         if (error)
  497                                 goto out;
  498                 }
  499                 np->n_attrstamp = 0;
  500                 error = VOP_GETATTR(vp, &vattr, cred);
  501                 if (error)
  502                         goto out;
  503                 mtx_lock(&np->n_mtx);
  504                 np->n_mtime = vattr.va_mtime;
  505                 mtx_unlock(&np->n_mtx);
  506         } else {
  507                 mtx_unlock(&np->n_mtx);
  508                 error = VOP_GETATTR(vp, &vattr, cred);
  509                 if (error)
  510                         return (error);
  511                 mtx_lock(&np->n_mtx);
  512                 if ((np->n_flag & NSIZECHANGED)
  513                     || (NFS_TIMESPEC_COMPARE(&np->n_mtime, &vattr.va_mtime))) {
  514                         mtx_unlock(&np->n_mtx);
  515                         if (vp->v_type == VDIR)
  516                                 ncl_invaldir(vp);
  517                         error = ncl_vinvalbuf(vp, V_SAVE, td, 1);
  518                         if (error)
  519                                 goto out;
  520                         mtx_lock(&np->n_mtx);
  521                         np->n_mtime = vattr.va_mtime;
  522                         np->n_flag &= ~NSIZECHANGED;
  523                 }
  524                 mtx_unlock(&np->n_mtx);
  525         }
  526 out:    
  527         ncl_downgrade_vnlock(vp, old_lock);
  528         return error;
  529 }
  530 
  531 /*
  532  * Vnode op for read using bio
  533  */
  534 int
  535 ncl_bioread(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred)
  536 {
  537         struct nfsnode *np = VTONFS(vp);
  538         int biosize, i;
  539         struct buf *bp, *rabp;
  540         struct thread *td;
  541         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  542         daddr_t lbn, rabn;
  543         int bcount;
  544         int seqcount;
  545         int nra, error = 0, n = 0, on = 0;
  546 
  547 #ifdef DIAGNOSTIC
  548         if (uio->uio_rw != UIO_READ)
  549                 panic("ncl_read mode");
  550 #endif
  551         if (uio->uio_resid == 0)
  552                 return (0);
  553         if (uio->uio_offset < 0)        /* XXX VDIR cookies can be negative */
  554                 return (EINVAL);
  555         td = uio->uio_td;
  556 
  557         mtx_lock(&nmp->nm_mtx);
  558         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  559             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  560                 mtx_unlock(&nmp->nm_mtx);
  561                 (void)ncl_fsinfo(nmp, vp, cred, td);
  562                 mtx_lock(&nmp->nm_mtx);
  563         }
  564         if (nmp->nm_rsize == 0 || nmp->nm_readdirsize == 0)
  565                 (void) newnfs_iosize(nmp);
  566         mtx_unlock(&nmp->nm_mtx);               
  567 
  568         if (vp->v_type != VDIR &&
  569             (uio->uio_offset + uio->uio_resid) > nmp->nm_maxfilesize)
  570                 return (EFBIG);
  571 
  572         if (newnfs_directio_enable && (ioflag & IO_DIRECT) && (vp->v_type == VREG))
  573                 /* No caching/ no readaheads. Just read data into the user buffer */
  574                 return ncl_readrpc(vp, uio, cred);
  575 
  576         biosize = vp->v_mount->mnt_stat.f_iosize;
  577         seqcount = (int)((off_t)(ioflag >> IO_SEQSHIFT) * biosize / BKVASIZE);
  578         
  579         error = nfs_bioread_check_cons(vp, td, cred);
  580         if (error)
  581                 return error;
  582 
  583         do {
  584             u_quad_t nsize;
  585                         
  586             mtx_lock(&np->n_mtx);
  587             nsize = np->n_size;
  588             mtx_unlock(&np->n_mtx);                 
  589 
  590             switch (vp->v_type) {
  591             case VREG:
  592                 NFSINCRGLOBAL(newnfsstats.biocache_reads);
  593                 lbn = uio->uio_offset / biosize;
  594                 on = uio->uio_offset & (biosize - 1);
  595 
  596                 /*
  597                  * Start the read ahead(s), as required.
  598                  */
  599                 if (nmp->nm_readahead > 0) {
  600                     for (nra = 0; nra < nmp->nm_readahead && nra < seqcount &&
  601                         (off_t)(lbn + 1 + nra) * biosize < nsize; nra++) {
  602                         rabn = lbn + 1 + nra;
  603                         if (incore(&vp->v_bufobj, rabn) == NULL) {
  604                             rabp = nfs_getcacheblk(vp, rabn, biosize, td);
  605                             if (!rabp) {
  606                                 error = newnfs_sigintr(nmp, td);
  607                                 if (error)
  608                                     return (error);
  609                                 else
  610                                     break;
  611                             }
  612                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  613                                 rabp->b_flags |= B_ASYNC;
  614                                 rabp->b_iocmd = BIO_READ;
  615                                 vfs_busy_pages(rabp, 0);
  616                                 if (ncl_asyncio(nmp, rabp, cred, td)) {
  617                                     rabp->b_flags |= B_INVAL;
  618                                     rabp->b_ioflags |= BIO_ERROR;
  619                                     vfs_unbusy_pages(rabp);
  620                                     brelse(rabp);
  621                                     break;
  622                                 }
  623                             } else {
  624                                 brelse(rabp);
  625                             }
  626                         }
  627                     }
  628                 }
  629 
  630                 /* Note that bcount is *not* DEV_BSIZE aligned. */
  631                 bcount = biosize;
  632                 if ((off_t)lbn * biosize >= nsize) {
  633                         bcount = 0;
  634                 } else if ((off_t)(lbn + 1) * biosize > nsize) {
  635                         bcount = nsize - (off_t)lbn * biosize;
  636                 }
  637                 bp = nfs_getcacheblk(vp, lbn, bcount, td);
  638 
  639                 if (!bp) {
  640                         error = newnfs_sigintr(nmp, td);
  641                         return (error ? error : EINTR);
  642                 }
  643 
  644                 /*
  645                  * If B_CACHE is not set, we must issue the read.  If this
  646                  * fails, we return an error.
  647                  */
  648 
  649                 if ((bp->b_flags & B_CACHE) == 0) {
  650                     bp->b_iocmd = BIO_READ;
  651                     vfs_busy_pages(bp, 0);
  652                     error = ncl_doio(vp, bp, cred, td);
  653                     if (error) {
  654                         brelse(bp);
  655                         return (error);
  656                     }
  657                 }
  658 
  659                 /*
  660                  * on is the offset into the current bp.  Figure out how many
  661                  * bytes we can copy out of the bp.  Note that bcount is
  662                  * NOT DEV_BSIZE aligned.
  663                  *
  664                  * Then figure out how many bytes we can copy into the uio.
  665                  */
  666 
  667                 n = 0;
  668                 if (on < bcount)
  669                         n = min((unsigned)(bcount - on), uio->uio_resid);
  670                 break;
  671             case VLNK:
  672                 NFSINCRGLOBAL(newnfsstats.biocache_readlinks);
  673                 bp = nfs_getcacheblk(vp, (daddr_t)0, NFS_MAXPATHLEN, td);
  674                 if (!bp) {
  675                         error = newnfs_sigintr(nmp, td);
  676                         return (error ? error : EINTR);
  677                 }
  678                 if ((bp->b_flags & B_CACHE) == 0) {
  679                     bp->b_iocmd = BIO_READ;
  680                     vfs_busy_pages(bp, 0);
  681                     error = ncl_doio(vp, bp, cred, td);
  682                     if (error) {
  683                         bp->b_ioflags |= BIO_ERROR;
  684                         brelse(bp);
  685                         return (error);
  686                     }
  687                 }
  688                 n = min(uio->uio_resid, NFS_MAXPATHLEN - bp->b_resid);
  689                 on = 0;
  690                 break;
  691             case VDIR:
  692                 NFSINCRGLOBAL(newnfsstats.biocache_readdirs);
  693                 if (np->n_direofoffset
  694                     && uio->uio_offset >= np->n_direofoffset) {
  695                     return (0);
  696                 }
  697                 lbn = (uoff_t)uio->uio_offset / NFS_DIRBLKSIZ;
  698                 on = uio->uio_offset & (NFS_DIRBLKSIZ - 1);
  699                 bp = nfs_getcacheblk(vp, lbn, NFS_DIRBLKSIZ, td);
  700                 if (!bp) {
  701                     error = newnfs_sigintr(nmp, td);
  702                     return (error ? error : EINTR);
  703                 }
  704                 if ((bp->b_flags & B_CACHE) == 0) {
  705                     bp->b_iocmd = BIO_READ;
  706                     vfs_busy_pages(bp, 0);
  707                     error = ncl_doio(vp, bp, cred, td);
  708                     if (error) {
  709                             brelse(bp);
  710                     }
  711                     while (error == NFSERR_BAD_COOKIE) {
  712                         ncl_invaldir(vp);
  713                         error = ncl_vinvalbuf(vp, 0, td, 1);
  714                         /*
  715                          * Yuck! The directory has been modified on the
  716                          * server. The only way to get the block is by
  717                          * reading from the beginning to get all the
  718                          * offset cookies.
  719                          *
  720                          * Leave the last bp intact unless there is an error.
  721                          * Loop back up to the while if the error is another
  722                          * NFSERR_BAD_COOKIE (double yuch!).
  723                          */
  724                         for (i = 0; i <= lbn && !error; i++) {
  725                             if (np->n_direofoffset
  726                                 && (i * NFS_DIRBLKSIZ) >= np->n_direofoffset)
  727                                     return (0);
  728                             bp = nfs_getcacheblk(vp, i, NFS_DIRBLKSIZ, td);
  729                             if (!bp) {
  730                                 error = newnfs_sigintr(nmp, td);
  731                                 return (error ? error : EINTR);
  732                             }
  733                             if ((bp->b_flags & B_CACHE) == 0) {
  734                                     bp->b_iocmd = BIO_READ;
  735                                     vfs_busy_pages(bp, 0);
  736                                     error = ncl_doio(vp, bp, cred, td);
  737                                     /*
  738                                      * no error + B_INVAL == directory EOF,
  739                                      * use the block.
  740                                      */
  741                                     if (error == 0 && (bp->b_flags & B_INVAL))
  742                                             break;
  743                             }
  744                             /*
  745                              * An error will throw away the block and the
  746                              * for loop will break out.  If no error and this
  747                              * is not the block we want, we throw away the
  748                              * block and go for the next one via the for loop.
  749                              */
  750                             if (error || i < lbn)
  751                                     brelse(bp);
  752                         }
  753                     }
  754                     /*
  755                      * The above while is repeated if we hit another cookie
  756                      * error.  If we hit an error and it wasn't a cookie error,
  757                      * we give up.
  758                      */
  759                     if (error)
  760                             return (error);
  761                 }
  762 
  763                 /*
  764                  * If not eof and read aheads are enabled, start one.
  765                  * (You need the current block first, so that you have the
  766                  *  directory offset cookie of the next block.)
  767                  */
  768                 if (nmp->nm_readahead > 0 &&
  769                     (bp->b_flags & B_INVAL) == 0 &&
  770                     (np->n_direofoffset == 0 ||
  771                     (lbn + 1) * NFS_DIRBLKSIZ < np->n_direofoffset) &&
  772                     incore(&vp->v_bufobj, lbn + 1) == NULL) {
  773                         rabp = nfs_getcacheblk(vp, lbn + 1, NFS_DIRBLKSIZ, td);
  774                         if (rabp) {
  775                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  776                                 rabp->b_flags |= B_ASYNC;
  777                                 rabp->b_iocmd = BIO_READ;
  778                                 vfs_busy_pages(rabp, 0);
  779                                 if (ncl_asyncio(nmp, rabp, cred, td)) {
  780                                     rabp->b_flags |= B_INVAL;
  781                                     rabp->b_ioflags |= BIO_ERROR;
  782                                     vfs_unbusy_pages(rabp);
  783                                     brelse(rabp);
  784                                 }
  785                             } else {
  786                                 brelse(rabp);
  787                             }
  788                         }
  789                 }
  790                 /*
  791                  * Unlike VREG files, whos buffer size ( bp->b_bcount ) is
  792                  * chopped for the EOF condition, we cannot tell how large
  793                  * NFS directories are going to be until we hit EOF.  So
  794                  * an NFS directory buffer is *not* chopped to its EOF.  Now,
  795                  * it just so happens that b_resid will effectively chop it
  796                  * to EOF.  *BUT* this information is lost if the buffer goes
  797                  * away and is reconstituted into a B_CACHE state ( due to
  798                  * being VMIO ) later.  So we keep track of the directory eof
  799                  * in np->n_direofoffset and chop it off as an extra step
  800                  * right here.
  801                  */
  802                 n = lmin(uio->uio_resid, NFS_DIRBLKSIZ - bp->b_resid - on);
  803                 if (np->n_direofoffset && n > np->n_direofoffset - uio->uio_offset)
  804                         n = np->n_direofoffset - uio->uio_offset;
  805                 break;
  806             default:
  807                 ncl_printf(" ncl_bioread: type %x unexpected\n", vp->v_type);
  808                 bp = NULL;
  809                 break;
  810             };
  811 
  812             if (n > 0) {
  813                     error = uiomove(bp->b_data + on, (int)n, uio);
  814             }
  815             if (vp->v_type == VLNK)
  816                 n = 0;
  817             if (bp != NULL)
  818                 brelse(bp);
  819         } while (error == 0 && uio->uio_resid > 0 && n > 0);
  820         return (error);
  821 }
  822 
  823 /*
  824  * The NFS write path cannot handle iovecs with len > 1. So we need to 
  825  * break up iovecs accordingly (restricting them to wsize).
  826  * For the SYNC case, we can do this with 1 copy (user buffer -> mbuf). 
  827  * For the ASYNC case, 2 copies are needed. The first a copy from the 
  828  * user buffer to a staging buffer and then a second copy from the staging
  829  * buffer to mbufs. This can be optimized by copying from the user buffer
  830  * directly into mbufs and passing the chain down, but that requires a 
  831  * fair amount of re-working of the relevant codepaths (and can be done
  832  * later).
  833  */
  834 static int
  835 nfs_directio_write(vp, uiop, cred, ioflag)
  836         struct vnode *vp;
  837         struct uio *uiop;
  838         struct ucred *cred;
  839         int ioflag;
  840 {
  841         int error;
  842         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  843         struct thread *td = uiop->uio_td;
  844         int size;
  845         int wsize;
  846         
  847         mtx_lock(&nmp->nm_mtx);
  848         wsize = nmp->nm_wsize;
  849         mtx_unlock(&nmp->nm_mtx);
  850         if (ioflag & IO_SYNC) {
  851                 int iomode, must_commit;
  852                 struct uio uio;
  853                 struct iovec iov;
  854 do_sync:
  855                 while (uiop->uio_resid > 0) {
  856                         size = min(uiop->uio_resid, wsize);
  857                         size = min(uiop->uio_iov->iov_len, size);
  858                         iov.iov_base = uiop->uio_iov->iov_base;
  859                         iov.iov_len = size;
  860                         uio.uio_iov = &iov;
  861                         uio.uio_iovcnt = 1;
  862                         uio.uio_offset = uiop->uio_offset;
  863                         uio.uio_resid = size;
  864                         uio.uio_segflg = UIO_USERSPACE;
  865                         uio.uio_rw = UIO_WRITE;
  866                         uio.uio_td = td;
  867                         iomode = NFSWRITE_FILESYNC;
  868                         error = ncl_writerpc(vp, &uio, cred, &iomode,
  869                             &must_commit);
  870                         KASSERT((must_commit == 0), 
  871                                 ("ncl_directio_write: Did not commit write"));
  872                         if (error)
  873                                 return (error);
  874                         uiop->uio_offset += size;
  875                         uiop->uio_resid -= size;
  876                         if (uiop->uio_iov->iov_len <= size) {
  877                                 uiop->uio_iovcnt--;
  878                                 uiop->uio_iov++;
  879                         } else {
  880                                 uiop->uio_iov->iov_base = 
  881                                         (char *)uiop->uio_iov->iov_base + size;
  882                                 uiop->uio_iov->iov_len -= size;
  883                         }
  884                 }
  885         } else {
  886                 struct uio *t_uio;
  887                 struct iovec *t_iov;
  888                 struct buf *bp;
  889                 
  890                 /*
  891                  * Break up the write into blocksize chunks and hand these
  892                  * over to nfsiod's for write back.
  893                  * Unfortunately, this incurs a copy of the data. Since 
  894                  * the user could modify the buffer before the write is 
  895                  * initiated.
  896                  * 
  897                  * The obvious optimization here is that one of the 2 copies
  898                  * in the async write path can be eliminated by copying the
  899                  * data here directly into mbufs and passing the mbuf chain
  900                  * down. But that will require a fair amount of re-working
  901                  * of the code and can be done if there's enough interest
  902                  * in NFS directio access.
  903                  */
  904                 while (uiop->uio_resid > 0) {
  905                         size = min(uiop->uio_resid, wsize);
  906                         size = min(uiop->uio_iov->iov_len, size);
  907                         bp = getpbuf(&ncl_pbuf_freecnt);
  908                         t_uio = malloc(sizeof(struct uio), M_NFSDIRECTIO, M_WAITOK);
  909                         t_iov = malloc(sizeof(struct iovec), M_NFSDIRECTIO, M_WAITOK);
  910                         t_iov->iov_base = malloc(size, M_NFSDIRECTIO, M_WAITOK);
  911                         t_iov->iov_len = size;
  912                         t_uio->uio_iov = t_iov;
  913                         t_uio->uio_iovcnt = 1;
  914                         t_uio->uio_offset = uiop->uio_offset;
  915                         t_uio->uio_resid = size;
  916                         t_uio->uio_segflg = UIO_SYSSPACE;
  917                         t_uio->uio_rw = UIO_WRITE;
  918                         t_uio->uio_td = td;
  919                         bcopy(uiop->uio_iov->iov_base, t_iov->iov_base, size);
  920                         bp->b_flags |= B_DIRECT;
  921                         bp->b_iocmd = BIO_WRITE;
  922                         if (cred != NOCRED) {
  923                                 crhold(cred);
  924                                 bp->b_wcred = cred;
  925                         } else 
  926                                 bp->b_wcred = NOCRED;                   
  927                         bp->b_caller1 = (void *)t_uio;
  928                         bp->b_vp = vp;
  929                         error = ncl_asyncio(nmp, bp, NOCRED, td);
  930                         if (error) {
  931                                 free(t_iov->iov_base, M_NFSDIRECTIO);
  932                                 free(t_iov, M_NFSDIRECTIO);
  933                                 free(t_uio, M_NFSDIRECTIO);
  934                                 bp->b_vp = NULL;
  935                                 relpbuf(bp, &ncl_pbuf_freecnt);
  936                                 if (error == EINTR)
  937                                         return (error);
  938                                 goto do_sync;
  939                         }
  940                         uiop->uio_offset += size;
  941                         uiop->uio_resid -= size;
  942                         if (uiop->uio_iov->iov_len <= size) {
  943                                 uiop->uio_iovcnt--;
  944                                 uiop->uio_iov++;
  945                         } else {
  946                                 uiop->uio_iov->iov_base = 
  947                                         (char *)uiop->uio_iov->iov_base + size;
  948                                 uiop->uio_iov->iov_len -= size;
  949                         }
  950                 }
  951         }
  952         return (0);
  953 }
  954 
  955 /*
  956  * Vnode op for write using bio
  957  */
  958 int
  959 ncl_write(struct vop_write_args *ap)
  960 {
  961         int biosize;
  962         struct uio *uio = ap->a_uio;
  963         struct thread *td = uio->uio_td;
  964         struct vnode *vp = ap->a_vp;
  965         struct nfsnode *np = VTONFS(vp);
  966         struct ucred *cred = ap->a_cred;
  967         int ioflag = ap->a_ioflag;
  968         struct buf *bp;
  969         struct vattr vattr;
  970         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  971         daddr_t lbn;
  972         int bcount;
  973         int n, on, error = 0;
  974         struct proc *p = td?td->td_proc:NULL;
  975 
  976 #ifdef DIAGNOSTIC
  977         if (uio->uio_rw != UIO_WRITE)
  978                 panic("ncl_write mode");
  979         if (uio->uio_segflg == UIO_USERSPACE && uio->uio_td != curthread)
  980                 panic("ncl_write proc");
  981 #endif
  982         if (vp->v_type != VREG)
  983                 return (EIO);
  984         mtx_lock(&np->n_mtx);
  985         if (np->n_flag & NWRITEERR) {
  986                 np->n_flag &= ~NWRITEERR;
  987                 mtx_unlock(&np->n_mtx);
  988                 return (np->n_error);
  989         } else
  990                 mtx_unlock(&np->n_mtx);
  991         mtx_lock(&nmp->nm_mtx);
  992         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  993             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  994                 mtx_unlock(&nmp->nm_mtx);
  995                 (void)ncl_fsinfo(nmp, vp, cred, td);
  996                 mtx_lock(&nmp->nm_mtx);
  997         }
  998         if (nmp->nm_wsize == 0)
  999                 (void) newnfs_iosize(nmp);
 1000         mtx_unlock(&nmp->nm_mtx);
 1001 
 1002         /*
 1003          * Synchronously flush pending buffers if we are in synchronous
 1004          * mode or if we are appending.
 1005          */
 1006         if (ioflag & (IO_APPEND | IO_SYNC)) {
 1007                 mtx_lock(&np->n_mtx);
 1008                 if (np->n_flag & NMODIFIED) {
 1009                         mtx_unlock(&np->n_mtx);
 1010 #ifdef notyet /* Needs matching nonblock semantics elsewhere, too. */
 1011                         /*
 1012                          * Require non-blocking, synchronous writes to
 1013                          * dirty files to inform the program it needs
 1014                          * to fsync(2) explicitly.
 1015                          */
 1016                         if (ioflag & IO_NDELAY)
 1017                                 return (EAGAIN);
 1018 #endif
 1019 flush_and_restart:
 1020                         np->n_attrstamp = 0;
 1021                         error = ncl_vinvalbuf(vp, V_SAVE, td, 1);
 1022                         if (error)
 1023                                 return (error);
 1024                 } else
 1025                         mtx_unlock(&np->n_mtx);
 1026         }
 1027 
 1028         /*
 1029          * If IO_APPEND then load uio_offset.  We restart here if we cannot
 1030          * get the append lock.
 1031          */
 1032         if (ioflag & IO_APPEND) {
 1033                 np->n_attrstamp = 0;
 1034                 error = VOP_GETATTR(vp, &vattr, cred);
 1035                 if (error)
 1036                         return (error);
 1037                 mtx_lock(&np->n_mtx);
 1038                 uio->uio_offset = np->n_size;
 1039                 mtx_unlock(&np->n_mtx);
 1040         }
 1041 
 1042         if (uio->uio_offset < 0)
 1043                 return (EINVAL);
 1044         if ((uio->uio_offset + uio->uio_resid) > nmp->nm_maxfilesize)
 1045                 return (EFBIG);
 1046         if (uio->uio_resid == 0)
 1047                 return (0);
 1048 
 1049         if (newnfs_directio_enable && (ioflag & IO_DIRECT) && vp->v_type == VREG)
 1050                 return nfs_directio_write(vp, uio, cred, ioflag);
 1051 
 1052         /*
 1053          * Maybe this should be above the vnode op call, but so long as
 1054          * file servers have no limits, i don't think it matters
 1055          */
 1056         if (p != NULL) {
 1057                 PROC_LOCK(p);
 1058                 if (uio->uio_offset + uio->uio_resid >
 1059                     lim_cur(p, RLIMIT_FSIZE)) {
 1060                         psignal(p, SIGXFSZ);
 1061                         PROC_UNLOCK(p);
 1062                         return (EFBIG);
 1063                 }
 1064                 PROC_UNLOCK(p);
 1065         }
 1066 
 1067         biosize = vp->v_mount->mnt_stat.f_iosize;
 1068         /*
 1069          * Find all of this file's B_NEEDCOMMIT buffers.  If our writes
 1070          * would exceed the local maximum per-file write commit size when
 1071          * combined with those, we must decide whether to flush,
 1072          * go synchronous, or return error.  We don't bother checking
 1073          * IO_UNIT -- we just make all writes atomic anyway, as there's
 1074          * no point optimizing for something that really won't ever happen.
 1075          */
 1076         if (!(ioflag & IO_SYNC)) {
 1077                 int nflag;
 1078 
 1079                 mtx_lock(&np->n_mtx);
 1080                 nflag = np->n_flag;
 1081                 mtx_unlock(&np->n_mtx);         
 1082                 int needrestart = 0;
 1083                 if (nmp->nm_wcommitsize < uio->uio_resid) {
 1084                         /*
 1085                          * If this request could not possibly be completed
 1086                          * without exceeding the maximum outstanding write
 1087                          * commit size, see if we can convert it into a
 1088                          * synchronous write operation.
 1089                          */
 1090                         if (ioflag & IO_NDELAY)
 1091                                 return (EAGAIN);
 1092                         ioflag |= IO_SYNC;
 1093                         if (nflag & NMODIFIED)
 1094                                 needrestart = 1;
 1095                 } else if (nflag & NMODIFIED) {
 1096                         int wouldcommit = 0;
 1097                         BO_LOCK(&vp->v_bufobj);
 1098                         if (vp->v_bufobj.bo_dirty.bv_cnt != 0) {
 1099                                 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd,
 1100                                     b_bobufs) {
 1101                                         if (bp->b_flags & B_NEEDCOMMIT)
 1102                                                 wouldcommit += bp->b_bcount;
 1103                                 }
 1104                         }
 1105                         BO_UNLOCK(&vp->v_bufobj);
 1106                         /*
 1107                          * Since we're not operating synchronously and
 1108                          * bypassing the buffer cache, we are in a commit
 1109                          * and holding all of these buffers whether
 1110                          * transmitted or not.  If not limited, this
 1111                          * will lead to the buffer cache deadlocking,
 1112                          * as no one else can flush our uncommitted buffers.
 1113                          */
 1114                         wouldcommit += uio->uio_resid;
 1115                         /*
 1116                          * If we would initially exceed the maximum
 1117                          * outstanding write commit size, flush and restart.
 1118                          */
 1119                         if (wouldcommit > nmp->nm_wcommitsize)
 1120                                 needrestart = 1;
 1121                 }
 1122                 if (needrestart)
 1123                         goto flush_and_restart;
 1124         }
 1125 
 1126         do {
 1127                 NFSINCRGLOBAL(newnfsstats.biocache_writes);
 1128                 lbn = uio->uio_offset / biosize;
 1129                 on = uio->uio_offset & (biosize-1);
 1130                 n = min((unsigned)(biosize - on), uio->uio_resid);
 1131 again:
 1132                 /*
 1133                  * Handle direct append and file extension cases, calculate
 1134                  * unaligned buffer size.
 1135                  */
 1136                 mtx_lock(&np->n_mtx);
 1137                 if (uio->uio_offset == np->n_size && n) {
 1138                         mtx_unlock(&np->n_mtx);
 1139                         /*
 1140                          * Get the buffer (in its pre-append state to maintain
 1141                          * B_CACHE if it was previously set).  Resize the
 1142                          * nfsnode after we have locked the buffer to prevent
 1143                          * readers from reading garbage.
 1144                          */
 1145                         bcount = on;
 1146                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1147 
 1148                         if (bp != NULL) {
 1149                                 long save;
 1150 
 1151                                 mtx_lock(&np->n_mtx);
 1152                                 np->n_size = uio->uio_offset + n;
 1153                                 np->n_flag |= NMODIFIED;
 1154                                 vnode_pager_setsize(vp, np->n_size);
 1155                                 mtx_unlock(&np->n_mtx);
 1156 
 1157                                 save = bp->b_flags & B_CACHE;
 1158                                 bcount += n;
 1159                                 allocbuf(bp, bcount);
 1160                                 bp->b_flags |= save;
 1161                         }
 1162                 } else {
 1163                         /*
 1164                          * Obtain the locked cache block first, and then
 1165                          * adjust the file's size as appropriate.
 1166                          */
 1167                         bcount = on + n;
 1168                         if ((off_t)lbn * biosize + bcount < np->n_size) {
 1169                                 if ((off_t)(lbn + 1) * biosize < np->n_size)
 1170                                         bcount = biosize;
 1171                                 else
 1172                                         bcount = np->n_size - (off_t)lbn * biosize;
 1173                         }
 1174                         mtx_unlock(&np->n_mtx);
 1175                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1176                         mtx_lock(&np->n_mtx);
 1177                         if (uio->uio_offset + n > np->n_size) {
 1178                                 np->n_size = uio->uio_offset + n;
 1179                                 np->n_flag |= NMODIFIED;
 1180                                 vnode_pager_setsize(vp, np->n_size);
 1181                         }
 1182                         mtx_unlock(&np->n_mtx);
 1183                 }
 1184 
 1185                 if (!bp) {
 1186                         error = newnfs_sigintr(nmp, td);
 1187                         if (!error)
 1188                                 error = EINTR;
 1189                         break;
 1190                 }
 1191 
 1192                 /*
 1193                  * Issue a READ if B_CACHE is not set.  In special-append
 1194                  * mode, B_CACHE is based on the buffer prior to the write
 1195                  * op and is typically set, avoiding the read.  If a read
 1196                  * is required in special append mode, the server will
 1197                  * probably send us a short-read since we extended the file
 1198                  * on our end, resulting in b_resid == 0 and, thusly,
 1199                  * B_CACHE getting set.
 1200                  *
 1201                  * We can also avoid issuing the read if the write covers
 1202                  * the entire buffer.  We have to make sure the buffer state
 1203                  * is reasonable in this case since we will not be initiating
 1204                  * I/O.  See the comments in kern/vfs_bio.c's getblk() for
 1205                  * more information.
 1206                  *
 1207                  * B_CACHE may also be set due to the buffer being cached
 1208                  * normally.
 1209                  */
 1210 
 1211                 if (on == 0 && n == bcount) {
 1212                         bp->b_flags |= B_CACHE;
 1213                         bp->b_flags &= ~B_INVAL;
 1214                         bp->b_ioflags &= ~BIO_ERROR;
 1215                 }
 1216 
 1217                 if ((bp->b_flags & B_CACHE) == 0) {
 1218                         bp->b_iocmd = BIO_READ;
 1219                         vfs_busy_pages(bp, 0);
 1220                         error = ncl_doio(vp, bp, cred, td);
 1221                         if (error) {
 1222                                 brelse(bp);
 1223                                 break;
 1224                         }
 1225                 }
 1226                 if (bp->b_wcred == NOCRED)
 1227                         bp->b_wcred = crhold(cred);
 1228                 mtx_lock(&np->n_mtx);
 1229                 np->n_flag |= NMODIFIED;
 1230                 mtx_unlock(&np->n_mtx);
 1231 
 1232                 /*
 1233                  * If dirtyend exceeds file size, chop it down.  This should
 1234                  * not normally occur but there is an append race where it
 1235                  * might occur XXX, so we log it.
 1236                  *
 1237                  * If the chopping creates a reverse-indexed or degenerate
 1238                  * situation with dirtyoff/end, we 0 both of them.
 1239                  */
 1240 
 1241                 if (bp->b_dirtyend > bcount) {
 1242                         ncl_printf("NFS append race @%lx:%d\n",
 1243                             (long)bp->b_blkno * DEV_BSIZE,
 1244                             bp->b_dirtyend - bcount);
 1245                         bp->b_dirtyend = bcount;
 1246                 }
 1247 
 1248                 if (bp->b_dirtyoff >= bp->b_dirtyend)
 1249                         bp->b_dirtyoff = bp->b_dirtyend = 0;
 1250 
 1251                 /*
 1252                  * If the new write will leave a contiguous dirty
 1253                  * area, just update the b_dirtyoff and b_dirtyend,
 1254                  * otherwise force a write rpc of the old dirty area.
 1255                  *
 1256                  * While it is possible to merge discontiguous writes due to
 1257                  * our having a B_CACHE buffer ( and thus valid read data
 1258                  * for the hole), we don't because it could lead to
 1259                  * significant cache coherency problems with multiple clients,
 1260                  * especially if locking is implemented later on.
 1261                  *
 1262                  * as an optimization we could theoretically maintain
 1263                  * a linked list of discontinuous areas, but we would still
 1264                  * have to commit them separately so there isn't much
 1265                  * advantage to it except perhaps a bit of asynchronization.
 1266                  */
 1267 
 1268                 if (bp->b_dirtyend > 0 &&
 1269                     (on > bp->b_dirtyend || (on + n) < bp->b_dirtyoff)) {
 1270                         if (bwrite(bp) == EINTR) {
 1271                                 error = EINTR;
 1272                                 break;
 1273                         }
 1274                         goto again;
 1275                 }
 1276 
 1277                 error = uiomove((char *)bp->b_data + on, n, uio);
 1278 
 1279                 /*
 1280                  * Since this block is being modified, it must be written
 1281                  * again and not just committed.  Since write clustering does
 1282                  * not work for the stage 1 data write, only the stage 2
 1283                  * commit rpc, we have to clear B_CLUSTEROK as well.
 1284                  */
 1285                 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1286 
 1287                 if (error) {
 1288                         bp->b_ioflags |= BIO_ERROR;
 1289                         brelse(bp);
 1290                         break;
 1291                 }
 1292 
 1293                 /*
 1294                  * Only update dirtyoff/dirtyend if not a degenerate
 1295                  * condition.
 1296                  */
 1297                 if (n) {
 1298                         if (bp->b_dirtyend > 0) {
 1299                                 bp->b_dirtyoff = min(on, bp->b_dirtyoff);
 1300                                 bp->b_dirtyend = max((on + n), bp->b_dirtyend);
 1301                         } else {
 1302                                 bp->b_dirtyoff = on;
 1303                                 bp->b_dirtyend = on + n;
 1304                         }
 1305                         vfs_bio_set_valid(bp, on, n);
 1306                 }
 1307 
 1308                 /*
 1309                  * If IO_SYNC do bwrite().
 1310                  *
 1311                  * IO_INVAL appears to be unused.  The idea appears to be
 1312                  * to turn off caching in this case.  Very odd.  XXX
 1313                  */
 1314                 if ((ioflag & IO_SYNC)) {
 1315                         if (ioflag & IO_INVAL)
 1316                                 bp->b_flags |= B_NOCACHE;
 1317                         error = bwrite(bp);
 1318                         if (error)
 1319                                 break;
 1320                 } else if ((n + on) == biosize) {
 1321                         bp->b_flags |= B_ASYNC;
 1322                         (void) ncl_writebp(bp, 0, NULL);
 1323                 } else {
 1324                         bdwrite(bp);
 1325                 }
 1326         } while (uio->uio_resid > 0 && n > 0);
 1327 
 1328         return (error);
 1329 }
 1330 
 1331 /*
 1332  * Get an nfs cache block.
 1333  *
 1334  * Allocate a new one if the block isn't currently in the cache
 1335  * and return the block marked busy. If the calling process is
 1336  * interrupted by a signal for an interruptible mount point, return
 1337  * NULL.
 1338  *
 1339  * The caller must carefully deal with the possible B_INVAL state of
 1340  * the buffer.  ncl_doio() clears B_INVAL (and ncl_asyncio() clears it
 1341  * indirectly), so synchronous reads can be issued without worrying about
 1342  * the B_INVAL state.  We have to be a little more careful when dealing
 1343  * with writes (see comments in nfs_write()) when extending a file past
 1344  * its EOF.
 1345  */
 1346 static struct buf *
 1347 nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size, struct thread *td)
 1348 {
 1349         struct buf *bp;
 1350         struct mount *mp;
 1351         struct nfsmount *nmp;
 1352 
 1353         mp = vp->v_mount;
 1354         nmp = VFSTONFS(mp);
 1355 
 1356         if (nmp->nm_flag & NFSMNT_INT) {
 1357                 sigset_t oldset;
 1358 
 1359                 ncl_set_sigmask(td, &oldset);
 1360                 bp = getblk(vp, bn, size, NFS_PCATCH, 0, 0);
 1361                 ncl_restore_sigmask(td, &oldset);
 1362                 while (bp == NULL) {
 1363                         if (newnfs_sigintr(nmp, td))
 1364                                 return (NULL);
 1365                         bp = getblk(vp, bn, size, 0, 2 * hz, 0);
 1366                 }
 1367         } else {
 1368                 bp = getblk(vp, bn, size, 0, 0, 0);
 1369         }
 1370 
 1371         if (vp->v_type == VREG) {
 1372                 int biosize;
 1373 
 1374                 biosize = mp->mnt_stat.f_iosize;
 1375                 bp->b_blkno = bn * (biosize / DEV_BSIZE);
 1376         }
 1377         return (bp);
 1378 }
 1379 
 1380 /*
 1381  * Flush and invalidate all dirty buffers. If another process is already
 1382  * doing the flush, just wait for completion.
 1383  */
 1384 int
 1385 ncl_vinvalbuf(struct vnode *vp, int flags, struct thread *td, int intrflg)
 1386 {
 1387         struct nfsnode *np = VTONFS(vp);
 1388         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
 1389         int error = 0, slpflag, slptimeo;
 1390         int old_lock = 0;
 1391 
 1392         ASSERT_VOP_LOCKED(vp, "ncl_vinvalbuf");
 1393 
 1394         if ((nmp->nm_flag & NFSMNT_INT) == 0)
 1395                 intrflg = 0;
 1396         if ((nmp->nm_mountp->mnt_kern_flag & MNTK_UNMOUNTF))
 1397                 intrflg = 1;
 1398         if (intrflg) {
 1399                 slpflag = NFS_PCATCH;
 1400                 slptimeo = 2 * hz;
 1401         } else {
 1402                 slpflag = 0;
 1403                 slptimeo = 0;
 1404         }
 1405 
 1406         old_lock = ncl_upgrade_vnlock(vp);
 1407         if (vp->v_iflag & VI_DOOMED) {
 1408                 /*
 1409                  * Since vgonel() uses the generic vinvalbuf() to flush
 1410                  * dirty buffers and it does not call this function, it
 1411                  * is safe to just return OK when VI_DOOMED is set.
 1412                  */
 1413                 ncl_downgrade_vnlock(vp, old_lock);
 1414                 return (0);
 1415         }
 1416 
 1417         /*
 1418          * Now, flush as required.
 1419          */
 1420         if ((flags & V_SAVE) && (vp->v_bufobj.bo_object != NULL)) {
 1421                 VM_OBJECT_LOCK(vp->v_bufobj.bo_object);
 1422                 vm_object_page_clean(vp->v_bufobj.bo_object, 0, 0, OBJPC_SYNC);
 1423                 VM_OBJECT_UNLOCK(vp->v_bufobj.bo_object);
 1424                 /*
 1425                  * If the page clean was interrupted, fail the invalidation.
 1426                  * Not doing so, we run the risk of losing dirty pages in the 
 1427                  * vinvalbuf() call below.
 1428                  */
 1429                 if (intrflg && (error = newnfs_sigintr(nmp, td)))
 1430                         goto out;
 1431         }
 1432 
 1433         error = vinvalbuf(vp, flags, slpflag, 0);
 1434         while (error) {
 1435                 if (intrflg && (error = newnfs_sigintr(nmp, td)))
 1436                         goto out;
 1437                 error = vinvalbuf(vp, flags, 0, slptimeo);
 1438         }
 1439         mtx_lock(&np->n_mtx);
 1440         if (np->n_directio_asyncwr == 0)
 1441                 np->n_flag &= ~NMODIFIED;
 1442         mtx_unlock(&np->n_mtx);
 1443 out:
 1444         ncl_downgrade_vnlock(vp, old_lock);
 1445         return error;
 1446 }
 1447 
 1448 /*
 1449  * Initiate asynchronous I/O. Return an error if no nfsiods are available.
 1450  * This is mainly to avoid queueing async I/O requests when the nfsiods
 1451  * are all hung on a dead server.
 1452  *
 1453  * Note: ncl_asyncio() does not clear (BIO_ERROR|B_INVAL) but when the bp
 1454  * is eventually dequeued by the async daemon, ncl_doio() *will*.
 1455  */
 1456 int
 1457 ncl_asyncio(struct nfsmount *nmp, struct buf *bp, struct ucred *cred, struct thread *td)
 1458 {
 1459         int iod;
 1460         int gotiod;
 1461         int slpflag = 0;
 1462         int slptimeo = 0;
 1463         int error, error2;
 1464 
 1465         /*
 1466          * Unless iothreadcnt is set > 0, don't bother with async I/O
 1467          * threads. For LAN environments, they don't buy any significant
 1468          * performance improvement that you can't get with large block
 1469          * sizes.
 1470          */
 1471         if (nmp->nm_readahead == 0)
 1472                 return (EPERM);
 1473 
 1474         /*
 1475          * Commits are usually short and sweet so lets save some cpu and
 1476          * leave the async daemons for more important rpc's (such as reads
 1477          * and writes).
 1478          */
 1479         mtx_lock(&ncl_iod_mutex);
 1480         if (bp->b_iocmd == BIO_WRITE && (bp->b_flags & B_NEEDCOMMIT) &&
 1481             (nmp->nm_bufqiods > ncl_numasync / 2)) {
 1482                 mtx_unlock(&ncl_iod_mutex);
 1483                 return(EIO);
 1484         }
 1485 again:
 1486         if (nmp->nm_flag & NFSMNT_INT)
 1487                 slpflag = NFS_PCATCH;
 1488         gotiod = FALSE;
 1489 
 1490         /*
 1491          * Find a free iod to process this request.
 1492          */
 1493         for (iod = 0; iod < ncl_numasync; iod++)
 1494                 if (ncl_iodwant[iod]) {
 1495                         gotiod = TRUE;
 1496                         break;
 1497                 }
 1498 
 1499         /*
 1500          * Try to create one if none are free.
 1501          */
 1502         if (!gotiod) {
 1503                 iod = ncl_nfsiodnew();
 1504                 if (iod != -1)
 1505                         gotiod = TRUE;
 1506         }
 1507 
 1508         if (gotiod) {
 1509                 /*
 1510                  * Found one, so wake it up and tell it which
 1511                  * mount to process.
 1512                  */
 1513                 NFS_DPF(ASYNCIO, ("ncl_asyncio: waking iod %d for mount %p\n",
 1514                     iod, nmp));
 1515                 ncl_iodwant[iod] = NULL;
 1516                 ncl_iodmount[iod] = nmp;
 1517                 nmp->nm_bufqiods++;
 1518                 wakeup(&ncl_iodwant[iod]);
 1519         }
 1520 
 1521         /*
 1522          * If none are free, we may already have an iod working on this mount
 1523          * point.  If so, it will process our request.
 1524          */
 1525         if (!gotiod) {
 1526                 if (nmp->nm_bufqiods > 0) {
 1527                         NFS_DPF(ASYNCIO,
 1528                                 ("ncl_asyncio: %d iods are already processing mount %p\n",
 1529                                  nmp->nm_bufqiods, nmp));
 1530                         gotiod = TRUE;
 1531                 }
 1532         }
 1533 
 1534         /*
 1535          * If we have an iod which can process the request, then queue
 1536          * the buffer.
 1537          */
 1538         if (gotiod) {
 1539                 /*
 1540                  * Ensure that the queue never grows too large.  We still want
 1541                  * to asynchronize so we block rather then return EIO.
 1542                  */
 1543                 while (nmp->nm_bufqlen >= 2*ncl_numasync) {
 1544                         NFS_DPF(ASYNCIO,
 1545                                 ("ncl_asyncio: waiting for mount %p queue to drain\n", nmp));
 1546                         nmp->nm_bufqwant = TRUE;
 1547                         error = ncl_msleep(td, &nmp->nm_bufq, &ncl_iod_mutex, 
 1548                                            slpflag | PRIBIO,
 1549                                            "nfsaio", slptimeo);
 1550                         if (error) {
 1551                                 error2 = newnfs_sigintr(nmp, td);
 1552                                 if (error2) {
 1553                                         mtx_unlock(&ncl_iod_mutex);                                     
 1554                                         return (error2);
 1555                                 }
 1556                                 if (slpflag == NFS_PCATCH) {
 1557                                         slpflag = 0;
 1558                                         slptimeo = 2 * hz;
 1559                                 }
 1560                         }
 1561                         /*
 1562                          * We might have lost our iod while sleeping,
 1563                          * so check and loop if nescessary.
 1564                          */
 1565                         if (nmp->nm_bufqiods == 0) {
 1566                                 NFS_DPF(ASYNCIO,
 1567                                         ("ncl_asyncio: no iods after mount %p queue was drained, looping\n", nmp));
 1568                                 goto again;
 1569                         }
 1570                 }
 1571 
 1572                 /* We might have lost our nfsiod */
 1573                 if (nmp->nm_bufqiods == 0) {
 1574                         NFS_DPF(ASYNCIO,
 1575                                 ("ncl_asyncio: no iods after mount %p queue was drained, looping\n", nmp));
 1576                         goto again;
 1577                 }
 1578 
 1579                 if (bp->b_iocmd == BIO_READ) {
 1580                         if (bp->b_rcred == NOCRED && cred != NOCRED)
 1581                                 bp->b_rcred = crhold(cred);
 1582                 } else {
 1583                         if (bp->b_wcred == NOCRED && cred != NOCRED)
 1584                                 bp->b_wcred = crhold(cred);
 1585                 }
 1586 
 1587                 if (bp->b_flags & B_REMFREE)
 1588                         bremfreef(bp);
 1589                 BUF_KERNPROC(bp);
 1590                 TAILQ_INSERT_TAIL(&nmp->nm_bufq, bp, b_freelist);
 1591                 nmp->nm_bufqlen++;
 1592                 if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1593                         mtx_lock(&(VTONFS(bp->b_vp))->n_mtx);                   
 1594                         VTONFS(bp->b_vp)->n_flag |= NMODIFIED;
 1595                         VTONFS(bp->b_vp)->n_directio_asyncwr++;
 1596                         mtx_unlock(&(VTONFS(bp->b_vp))->n_mtx);
 1597                 }
 1598                 mtx_unlock(&ncl_iod_mutex);
 1599                 return (0);
 1600         }
 1601 
 1602         mtx_unlock(&ncl_iod_mutex);
 1603 
 1604         /*
 1605          * All the iods are busy on other mounts, so return EIO to
 1606          * force the caller to process the i/o synchronously.
 1607          */
 1608         NFS_DPF(ASYNCIO, ("ncl_asyncio: no iods available, i/o is synchronous\n"));
 1609         return (EIO);
 1610 }
 1611 
 1612 void
 1613 ncl_doio_directwrite(struct buf *bp)
 1614 {
 1615         int iomode, must_commit;
 1616         struct uio *uiop = (struct uio *)bp->b_caller1;
 1617         char *iov_base = uiop->uio_iov->iov_base;
 1618         
 1619         iomode = NFSWRITE_FILESYNC;
 1620         uiop->uio_td = NULL; /* NULL since we're in nfsiod */
 1621         ncl_writerpc(bp->b_vp, uiop, bp->b_wcred, &iomode, &must_commit);
 1622         KASSERT((must_commit == 0), ("ncl_doio_directwrite: Did not commit write"));
 1623         free(iov_base, M_NFSDIRECTIO);
 1624         free(uiop->uio_iov, M_NFSDIRECTIO);
 1625         free(uiop, M_NFSDIRECTIO);
 1626         if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1627                 struct nfsnode *np = VTONFS(bp->b_vp);
 1628                 mtx_lock(&np->n_mtx);
 1629                 np->n_directio_asyncwr--;
 1630                 if (np->n_directio_asyncwr == 0) {
 1631                         np->n_flag &= ~NMODIFIED;
 1632                         if ((np->n_flag & NFSYNCWAIT)) {
 1633                                 np->n_flag &= ~NFSYNCWAIT;
 1634                                 wakeup((caddr_t)&np->n_directio_asyncwr);
 1635                         }
 1636                 }
 1637                 mtx_unlock(&np->n_mtx);
 1638         }
 1639         bp->b_vp = NULL;
 1640         relpbuf(bp, &ncl_pbuf_freecnt);
 1641 }
 1642 
 1643 /*
 1644  * Do an I/O operation to/from a cache block. This may be called
 1645  * synchronously or from an nfsiod.
 1646  */
 1647 int
 1648 ncl_doio(struct vnode *vp, struct buf *bp, struct ucred *cr, struct thread *td)
 1649 {
 1650         struct uio *uiop;
 1651         struct nfsnode *np;
 1652         struct nfsmount *nmp;
 1653         int error = 0, iomode, must_commit = 0;
 1654         struct uio uio;
 1655         struct iovec io;
 1656         struct proc *p = td ? td->td_proc : NULL;
 1657         uint8_t iocmd;
 1658         
 1659         np = VTONFS(vp);
 1660         nmp = VFSTONFS(vp->v_mount);
 1661         uiop = &uio;
 1662         uiop->uio_iov = &io;
 1663         uiop->uio_iovcnt = 1;
 1664         uiop->uio_segflg = UIO_SYSSPACE;
 1665         uiop->uio_td = td;
 1666 
 1667         /*
 1668          * clear BIO_ERROR and B_INVAL state prior to initiating the I/O.  We
 1669          * do this here so we do not have to do it in all the code that
 1670          * calls us.
 1671          */
 1672         bp->b_flags &= ~B_INVAL;
 1673         bp->b_ioflags &= ~BIO_ERROR;
 1674 
 1675         KASSERT(!(bp->b_flags & B_DONE), ("ncl_doio: bp %p already marked done", bp));
 1676         iocmd = bp->b_iocmd;
 1677         if (iocmd == BIO_READ) {
 1678             io.iov_len = uiop->uio_resid = bp->b_bcount;
 1679             io.iov_base = bp->b_data;
 1680             uiop->uio_rw = UIO_READ;
 1681 
 1682             switch (vp->v_type) {
 1683             case VREG:
 1684                 uiop->uio_offset = ((off_t)bp->b_blkno) * DEV_BSIZE;
 1685                 NFSINCRGLOBAL(newnfsstats.read_bios);
 1686                 error = ncl_readrpc(vp, uiop, cr);
 1687 
 1688                 if (!error) {
 1689                     if (uiop->uio_resid) {
 1690                         /*
 1691                          * If we had a short read with no error, we must have
 1692                          * hit a file hole.  We should zero-fill the remainder.
 1693                          * This can also occur if the server hits the file EOF.
 1694                          *
 1695                          * Holes used to be able to occur due to pending
 1696                          * writes, but that is not possible any longer.
 1697                          */
 1698                         int nread = bp->b_bcount - uiop->uio_resid;
 1699                         int left  = uiop->uio_resid;
 1700 
 1701                         if (left > 0)
 1702                                 bzero((char *)bp->b_data + nread, left);
 1703                         uiop->uio_resid = 0;
 1704                     }
 1705                 }
 1706                 /* ASSERT_VOP_LOCKED(vp, "ncl_doio"); */
 1707                 if (p && (vp->v_vflag & VV_TEXT)) {
 1708                         mtx_lock(&np->n_mtx);
 1709                         if (NFS_TIMESPEC_COMPARE(&np->n_mtime, &np->n_vattr.na_mtime)) {
 1710                                 mtx_unlock(&np->n_mtx);
 1711                                 PROC_LOCK(p);
 1712                                 killproc(p, "text file modification");
 1713                                 PROC_UNLOCK(p);
 1714                         } else
 1715                                 mtx_unlock(&np->n_mtx);
 1716                 }
 1717                 break;
 1718             case VLNK:
 1719                 uiop->uio_offset = (off_t)0;
 1720                 NFSINCRGLOBAL(newnfsstats.readlink_bios);
 1721                 error = ncl_readlinkrpc(vp, uiop, cr);
 1722                 break;
 1723             case VDIR:
 1724                 NFSINCRGLOBAL(newnfsstats.readdir_bios);
 1725                 uiop->uio_offset = ((u_quad_t)bp->b_lblkno) * NFS_DIRBLKSIZ;
 1726                 if ((nmp->nm_flag & NFSMNT_RDIRPLUS) != 0) {
 1727                         error = ncl_readdirplusrpc(vp, uiop, cr, td);
 1728                         if (error == NFSERR_NOTSUPP)
 1729                                 nmp->nm_flag &= ~NFSMNT_RDIRPLUS;
 1730                 }
 1731                 if ((nmp->nm_flag & NFSMNT_RDIRPLUS) == 0)
 1732                         error = ncl_readdirrpc(vp, uiop, cr, td);
 1733                 /*
 1734                  * end-of-directory sets B_INVAL but does not generate an
 1735                  * error.
 1736                  */
 1737                 if (error == 0 && uiop->uio_resid == bp->b_bcount)
 1738                         bp->b_flags |= B_INVAL;
 1739                 break;
 1740             default:
 1741                 ncl_printf("ncl_doio:  type %x unexpected\n", vp->v_type);
 1742                 break;
 1743             };
 1744             if (error) {
 1745                 bp->b_ioflags |= BIO_ERROR;
 1746                 bp->b_error = error;
 1747             }
 1748         } else {
 1749             /*
 1750              * If we only need to commit, try to commit
 1751              */
 1752             if (bp->b_flags & B_NEEDCOMMIT) {
 1753                     int retv;
 1754                     off_t off;
 1755 
 1756                     off = ((u_quad_t)bp->b_blkno) * DEV_BSIZE + bp->b_dirtyoff;
 1757                     retv = ncl_commit(vp, off, bp->b_dirtyend-bp->b_dirtyoff,
 1758                         bp->b_wcred, td);
 1759                     if (retv == 0) {
 1760                             bp->b_dirtyoff = bp->b_dirtyend = 0;
 1761                             bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1762                             bp->b_resid = 0;
 1763                             bufdone(bp);
 1764                             return (0);
 1765                     }
 1766                     if (retv == NFSERR_STALEWRITEVERF) {
 1767                             ncl_clearcommit(vp->v_mount);
 1768                     }
 1769             }
 1770 
 1771             /*
 1772              * Setup for actual write
 1773              */
 1774             mtx_lock(&np->n_mtx);
 1775             if ((off_t)bp->b_blkno * DEV_BSIZE + bp->b_dirtyend > np->n_size)
 1776                 bp->b_dirtyend = np->n_size - (off_t)bp->b_blkno * DEV_BSIZE;
 1777             mtx_unlock(&np->n_mtx);
 1778 
 1779             if (bp->b_dirtyend > bp->b_dirtyoff) {
 1780                 io.iov_len = uiop->uio_resid = bp->b_dirtyend
 1781                     - bp->b_dirtyoff;
 1782                 uiop->uio_offset = (off_t)bp->b_blkno * DEV_BSIZE
 1783                     + bp->b_dirtyoff;
 1784                 io.iov_base = (char *)bp->b_data + bp->b_dirtyoff;
 1785                 uiop->uio_rw = UIO_WRITE;
 1786                 NFSINCRGLOBAL(newnfsstats.write_bios);
 1787 
 1788                 if ((bp->b_flags & (B_ASYNC | B_NEEDCOMMIT | B_NOCACHE | B_CLUSTER)) == B_ASYNC)
 1789                     iomode = NFSWRITE_UNSTABLE;
 1790                 else
 1791                     iomode = NFSWRITE_FILESYNC;
 1792 
 1793                 error = ncl_writerpc(vp, uiop, cr, &iomode, &must_commit);
 1794 
 1795                 /*
 1796                  * When setting B_NEEDCOMMIT also set B_CLUSTEROK to try
 1797                  * to cluster the buffers needing commit.  This will allow
 1798                  * the system to submit a single commit rpc for the whole
 1799                  * cluster.  We can do this even if the buffer is not 100%
 1800                  * dirty (relative to the NFS blocksize), so we optimize the
 1801                  * append-to-file-case.
 1802                  *
 1803                  * (when clearing B_NEEDCOMMIT, B_CLUSTEROK must also be
 1804                  * cleared because write clustering only works for commit
 1805                  * rpc's, not for the data portion of the write).
 1806                  */
 1807 
 1808                 if (!error && iomode == NFSWRITE_UNSTABLE) {
 1809                     bp->b_flags |= B_NEEDCOMMIT;
 1810                     if (bp->b_dirtyoff == 0
 1811                         && bp->b_dirtyend == bp->b_bcount)
 1812                         bp->b_flags |= B_CLUSTEROK;
 1813                 } else {
 1814                     bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1815                 }
 1816 
 1817                 /*
 1818                  * For an interrupted write, the buffer is still valid
 1819                  * and the write hasn't been pushed to the server yet,
 1820                  * so we can't set BIO_ERROR and report the interruption
 1821                  * by setting B_EINTR. For the B_ASYNC case, B_EINTR
 1822                  * is not relevant, so the rpc attempt is essentially
 1823                  * a noop.  For the case of a V3 write rpc not being
 1824                  * committed to stable storage, the block is still
 1825                  * dirty and requires either a commit rpc or another
 1826                  * write rpc with iomode == NFSV3WRITE_FILESYNC before
 1827                  * the block is reused. This is indicated by setting
 1828                  * the B_DELWRI and B_NEEDCOMMIT flags.
 1829                  *
 1830                  * If the buffer is marked B_PAGING, it does not reside on
 1831                  * the vp's paging queues so we cannot call bdirty().  The
 1832                  * bp in this case is not an NFS cache block so we should
 1833                  * be safe. XXX
 1834                  *
 1835                  * The logic below breaks up errors into recoverable and 
 1836                  * unrecoverable. For the former, we clear B_INVAL|B_NOCACHE
 1837                  * and keep the buffer around for potential write retries.
 1838                  * For the latter (eg ESTALE), we toss the buffer away (B_INVAL)
 1839                  * and save the error in the nfsnode. This is less than ideal 
 1840                  * but necessary. Keeping such buffers around could potentially
 1841                  * cause buffer exhaustion eventually (they can never be written
 1842                  * out, so will get constantly be re-dirtied). It also causes
 1843                  * all sorts of vfs panics. For non-recoverable write errors, 
 1844                  * also invalidate the attrcache, so we'll be forced to go over
 1845                  * the wire for this object, returning an error to user on next
 1846                  * call (most of the time).
 1847                  */
 1848                 if (error == EINTR || error == EIO || error == ETIMEDOUT
 1849                     || (!error && (bp->b_flags & B_NEEDCOMMIT))) {
 1850                         int s;
 1851 
 1852                         s = splbio();
 1853                         bp->b_flags &= ~(B_INVAL|B_NOCACHE);
 1854                         if ((bp->b_flags & B_PAGING) == 0) {
 1855                             bdirty(bp);
 1856                             bp->b_flags &= ~B_DONE;
 1857                         }
 1858                         if (error && (bp->b_flags & B_ASYNC) == 0)
 1859                             bp->b_flags |= B_EINTR;
 1860                         splx(s);
 1861                 } else {
 1862                     if (error) {
 1863                         bp->b_ioflags |= BIO_ERROR;
 1864                         bp->b_flags |= B_INVAL;
 1865                         bp->b_error = np->n_error = error;
 1866                         mtx_lock(&np->n_mtx);
 1867                         np->n_flag |= NWRITEERR;
 1868                         np->n_attrstamp = 0;
 1869                         mtx_unlock(&np->n_mtx);
 1870                     }
 1871                     bp->b_dirtyoff = bp->b_dirtyend = 0;
 1872                 }
 1873             } else {
 1874                 bp->b_resid = 0;
 1875                 bufdone(bp);
 1876                 return (0);
 1877             }
 1878         }
 1879         bp->b_resid = uiop->uio_resid;
 1880         if (must_commit)
 1881             ncl_clearcommit(vp->v_mount);
 1882         bufdone(bp);
 1883         return (error);
 1884 }
 1885 
 1886 /*
 1887  * Used to aid in handling ftruncate() operations on the NFS client side.
 1888  * Truncation creates a number of special problems for NFS.  We have to
 1889  * throw away VM pages and buffer cache buffers that are beyond EOF, and
 1890  * we have to properly handle VM pages or (potentially dirty) buffers
 1891  * that straddle the truncation point.
 1892  */
 1893 
 1894 int
 1895 ncl_meta_setsize(struct vnode *vp, struct ucred *cred, struct thread *td, u_quad_t nsize)
 1896 {
 1897         struct nfsnode *np = VTONFS(vp);
 1898         u_quad_t tsize;
 1899         int biosize = vp->v_mount->mnt_stat.f_iosize;
 1900         int error = 0;
 1901 
 1902         mtx_lock(&np->n_mtx);
 1903         tsize = np->n_size;
 1904         np->n_size = nsize;
 1905         mtx_unlock(&np->n_mtx);
 1906 
 1907         if (nsize < tsize) {
 1908                 struct buf *bp;
 1909                 daddr_t lbn;
 1910                 int bufsize;
 1911 
 1912                 /*
 1913                  * vtruncbuf() doesn't get the buffer overlapping the 
 1914                  * truncation point.  We may have a B_DELWRI and/or B_CACHE
 1915                  * buffer that now needs to be truncated.
 1916                  */
 1917                 error = vtruncbuf(vp, cred, td, nsize, biosize);
 1918                 lbn = nsize / biosize;
 1919                 bufsize = nsize & (biosize - 1);
 1920                 bp = nfs_getcacheblk(vp, lbn, bufsize, td);
 1921                 if (!bp)
 1922                         return EINTR;
 1923                 if (bp->b_dirtyoff > bp->b_bcount)
 1924                         bp->b_dirtyoff = bp->b_bcount;
 1925                 if (bp->b_dirtyend > bp->b_bcount)
 1926                         bp->b_dirtyend = bp->b_bcount;
 1927                 bp->b_flags |= B_RELBUF;  /* don't leave garbage around */
 1928                 brelse(bp);
 1929         } else {
 1930                 vnode_pager_setsize(vp, nsize);
 1931         }
 1932         return(error);
 1933 }
 1934 

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