FreeBSD/Linux Kernel Cross Reference
sys/fs/nfsclient/nfs_clvnops.c

     /*-
      * Copyright (c) 1989, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * This code is derived from software contributed to Berkeley by
      * Rick Macklem at The University of Guelph.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      from nfs_vnops.c        8.16 (Berkeley) 5/27/95
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/8.0/sys/fs/nfsclient/nfs_clvnops.c 196622 2009-08-28 19:12:44Z zec $");
    
    /*
     * vnode op calls for Sun NFS version 2, 3 and 4
     */
    
    #include "opt_inet.h"
    
    #include <sys/param.h>
    #include <sys/kernel.h>
    #include <sys/systm.h>
    #include <sys/resourcevar.h>
    #include <sys/proc.h>
    #include <sys/mount.h>
    #include <sys/bio.h>
    #include <sys/buf.h>
    #include <sys/jail.h>
    #include <sys/malloc.h>
    #include <sys/mbuf.h>
    #include <sys/namei.h>
    #include <sys/socket.h>
    #include <sys/vnode.h>
    #include <sys/dirent.h>
    #include <sys/fcntl.h>
    #include <sys/lockf.h>
    #include <sys/stat.h>
    #include <sys/sysctl.h>
    #include <sys/signalvar.h>
    
    #include <vm/vm.h>
    #include <vm/vm_object.h>
    #include <vm/vm_extern.h>
    #include <vm/vm_object.h>
    
    
    #include <fs/nfs/nfsport.h>
    #include <fs/nfsclient/nfsnode.h>
    #include <fs/nfsclient/nfsmount.h>
    #include <fs/nfsclient/nfs.h>
    #include <fs/nfsclient/nfs_lock.h>
    
    #include <net/if.h>
    #include <netinet/in.h>
    #include <netinet/in_var.h>
    
    /* Defs */
    #define TRUE    1
    #define FALSE   0
    
    extern struct nfsstats newnfsstats;
    MALLOC_DECLARE(M_NEWNFSREQ);
    vop_advlock_t   *ncl_advlock_p = ncl_dolock;
    
    /*
     * Ifdef for FreeBSD-current merged buffer cache. It is unfortunate that these
     * calls are not in getblk() and brelse() so that they would not be necessary
     * here.
     */
    #ifndef B_VMIO
    #define vfs_busy_pages(bp, f)
    #endif
    
    static vop_read_t       nfsfifo_read;
    static vop_write_t      nfsfifo_write;
   static vop_close_t      nfsfifo_close;
   static int      nfs_setattrrpc(struct vnode *, struct vattr *, struct ucred *,
                       struct thread *);
   static vop_lookup_t     nfs_lookup;
   static vop_create_t     nfs_create;
   static vop_mknod_t      nfs_mknod;
   static vop_open_t       nfs_open;
   static vop_close_t      nfs_close;
   static vop_access_t     nfs_access;
   static vop_getattr_t    nfs_getattr;
   static vop_setattr_t    nfs_setattr;
   static vop_read_t       nfs_read;
   static vop_fsync_t      nfs_fsync;
   static vop_remove_t     nfs_remove;
   static vop_link_t       nfs_link;
   static vop_rename_t     nfs_rename;
   static vop_mkdir_t      nfs_mkdir;
   static vop_rmdir_t      nfs_rmdir;
   static vop_symlink_t    nfs_symlink;
   static vop_readdir_t    nfs_readdir;
   static vop_strategy_t   nfs_strategy;
   static vop_lock1_t      nfs_lock1;
   static  int     nfs_lookitup(struct vnode *, char *, int,
                       struct ucred *, struct thread *, struct nfsnode **);
   static  int     nfs_sillyrename(struct vnode *, struct vnode *,
                       struct componentname *);
   static vop_access_t     nfsspec_access;
   static vop_readlink_t   nfs_readlink;
   static vop_print_t      nfs_print;
   static vop_advlock_t    nfs_advlock;
   static vop_advlockasync_t nfs_advlockasync;
   #ifdef NFS4_ACL_EXTATTR_NAME
   static vop_getacl_t nfs_getacl;
   static vop_setacl_t nfs_setacl;
   #endif
   
   /*
    * Global vfs data structures for nfs
    */
   struct vop_vector newnfs_vnodeops = {
           .vop_default =          &default_vnodeops,
           .vop_access =           nfs_access,
           .vop_advlock =          nfs_advlock,
           .vop_advlockasync =     nfs_advlockasync,
           .vop_close =            nfs_close,
           .vop_create =           nfs_create,
           .vop_fsync =            nfs_fsync,
           .vop_getattr =          nfs_getattr,
           .vop_getpages =         ncl_getpages,
           .vop_putpages =         ncl_putpages,
           .vop_inactive =         ncl_inactive,
           .vop_link =             nfs_link,
           .vop_lock1 =            nfs_lock1,
           .vop_lookup =           nfs_lookup,
           .vop_mkdir =            nfs_mkdir,
           .vop_mknod =            nfs_mknod,
           .vop_open =             nfs_open,
           .vop_print =            nfs_print,
           .vop_read =             nfs_read,
           .vop_readdir =          nfs_readdir,
           .vop_readlink =         nfs_readlink,
           .vop_reclaim =          ncl_reclaim,
           .vop_remove =           nfs_remove,
           .vop_rename =           nfs_rename,
           .vop_rmdir =            nfs_rmdir,
           .vop_setattr =          nfs_setattr,
           .vop_strategy =         nfs_strategy,
           .vop_symlink =          nfs_symlink,
           .vop_write =            ncl_write,
   #ifdef NFS4_ACL_EXTATTR_NAME
           .vop_getacl =           nfs_getacl,
           .vop_setacl =           nfs_setacl,
   #endif
   };
   
   struct vop_vector newnfs_fifoops = {
           .vop_default =          &fifo_specops,
           .vop_access =           nfsspec_access,
           .vop_close =            nfsfifo_close,
           .vop_fsync =            nfs_fsync,
           .vop_getattr =          nfs_getattr,
           .vop_inactive =         ncl_inactive,
           .vop_print =            nfs_print,
           .vop_read =             nfsfifo_read,
           .vop_reclaim =          ncl_reclaim,
           .vop_setattr =          nfs_setattr,
           .vop_write =            nfsfifo_write,
   };
   
   static int nfs_mknodrpc(struct vnode *dvp, struct vnode **vpp,
       struct componentname *cnp, struct vattr *vap);
   static int nfs_removerpc(struct vnode *dvp, struct vnode *vp, char *name,
       int namelen, struct ucred *cred, struct thread *td);
   static int nfs_renamerpc(struct vnode *fdvp, struct vnode *fvp,
       char *fnameptr, int fnamelen, struct vnode *tdvp, struct vnode *tvp,
       char *tnameptr, int tnamelen, struct ucred *cred, struct thread *td);
   static int nfs_renameit(struct vnode *sdvp, struct vnode *svp,
       struct componentname *scnp, struct sillyrename *sp);
   
   /*
    * Global variables
    */
   #define DIRHDSIZ        (sizeof (struct dirent) - (MAXNAMLEN + 1))
   
   SYSCTL_DECL(_vfs_newnfs);
   
   static int      nfsaccess_cache_timeout = NFS_MAXATTRTIMO;
   SYSCTL_INT(_vfs_newnfs, OID_AUTO, access_cache_timeout, CTLFLAG_RW,
              &nfsaccess_cache_timeout, 0, "NFS ACCESS cache timeout");
   
   static int      nfs_prime_access_cache = 0;
   SYSCTL_INT(_vfs_newnfs, OID_AUTO, prime_access_cache, CTLFLAG_RW,
              &nfs_prime_access_cache, 0,
              "Prime NFS ACCESS cache when fetching attributes");
   
   static int      newnfs_commit_on_close = 0;
   SYSCTL_INT(_vfs_newnfs, OID_AUTO, commit_on_close, CTLFLAG_RW,
       &newnfs_commit_on_close, 0, "write+commit on close, else only write");
   
   static int      nfs_clean_pages_on_close = 1;
   SYSCTL_INT(_vfs_newnfs, OID_AUTO, clean_pages_on_close, CTLFLAG_RW,
              &nfs_clean_pages_on_close, 0, "NFS clean dirty pages on close");
   
   int newnfs_directio_enable = 0;
   SYSCTL_INT(_vfs_newnfs, OID_AUTO, directio_enable, CTLFLAG_RW,
              &newnfs_directio_enable, 0, "Enable NFS directio");
   
   static int newnfs_neglookup_enable = 1;
   SYSCTL_INT(_vfs_newnfs, OID_AUTO, neglookup_enable, CTLFLAG_RW,
       &newnfs_neglookup_enable, 0, "Enable NFS negative lookup caching");
   
   /*
    * This sysctl allows other processes to mmap a file that has been opened
    * O_DIRECT by a process.  In general, having processes mmap the file while
    * Direct IO is in progress can lead to Data Inconsistencies.  But, we allow
    * this by default to prevent DoS attacks - to prevent a malicious user from
    * opening up files O_DIRECT preventing other users from mmap'ing these
    * files.  "Protected" environments where stricter consistency guarantees are
    * required can disable this knob.  The process that opened the file O_DIRECT
    * cannot mmap() the file, because mmap'ed IO on an O_DIRECT open() is not
    * meaningful.
    */
   int newnfs_directio_allow_mmap = 1;
   SYSCTL_INT(_vfs_newnfs, OID_AUTO, directio_allow_mmap, CTLFLAG_RW,
              &newnfs_directio_allow_mmap, 0, "Enable mmaped IO on file with O_DIRECT opens");
   
   #if 0
   SYSCTL_INT(_vfs_newnfs, OID_AUTO, access_cache_hits, CTLFLAG_RD,
              &newnfsstats.accesscache_hits, 0, "NFS ACCESS cache hit count");
   
   SYSCTL_INT(_vfs_newnfs, OID_AUTO, access_cache_misses, CTLFLAG_RD,
              &newnfsstats.accesscache_misses, 0, "NFS ACCESS cache miss count");
   #endif
   
   #define NFSACCESS_ALL (NFSACCESS_READ | NFSACCESS_MODIFY                \
                            | NFSACCESS_EXTEND | NFSACCESS_EXECUTE \
                            | NFSACCESS_DELETE | NFSACCESS_LOOKUP)
   
   /*
    * SMP Locking Note :
    * The list of locks after the description of the lock is the ordering
    * of other locks acquired with the lock held.
    * np->n_mtx : Protects the fields in the nfsnode.
          VM Object Lock
          VI_MTX (acquired indirectly)
    * nmp->nm_mtx : Protects the fields in the nfsmount.
          rep->r_mtx
    * ncl_iod_mutex : Global lock, protects shared nfsiod state.
    * nfs_reqq_mtx : Global lock, protects the nfs_reqq list.
          nmp->nm_mtx
          rep->r_mtx
    * rep->r_mtx : Protects the fields in an nfsreq.
    */
   
   static int
   nfs34_access_otw(struct vnode *vp, int wmode, struct thread *td,
       struct ucred *cred, u_int32_t *retmode)
   {
           int error = 0, attrflag, i, lrupos;
           u_int32_t rmode;
           struct nfsnode *np = VTONFS(vp);
           struct nfsvattr nfsva;
   
           error = nfsrpc_accessrpc(vp, wmode, cred, td, &nfsva, &attrflag,
               &rmode, NULL);
           if (attrflag)
                   (void) nfscl_loadattrcache(&vp, &nfsva, NULL, NULL, 0, 1);
           if (!error) {
                   lrupos = 0;
                   mtx_lock(&np->n_mtx);
                   for (i = 0; i < NFS_ACCESSCACHESIZE; i++) {
                           if (np->n_accesscache[i].uid == cred->cr_uid) {
                                   np->n_accesscache[i].mode = rmode;
                                   np->n_accesscache[i].stamp = time_second;
                                   break;
                           }
                           if (i > 0 && np->n_accesscache[i].stamp <
                               np->n_accesscache[lrupos].stamp)
                                   lrupos = i;
                   }
                   if (i == NFS_ACCESSCACHESIZE) {
                           np->n_accesscache[lrupos].uid = cred->cr_uid;
                           np->n_accesscache[lrupos].mode = rmode;
                           np->n_accesscache[lrupos].stamp = time_second;
                   }
                   mtx_unlock(&np->n_mtx);
                   if (retmode != NULL)
                           *retmode = rmode;
           } else if (NFS_ISV4(vp)) {
                   error = nfscl_maperr(td, error, (uid_t)0, (gid_t)0);
           }
           return (error);
   }
   
   /*
    * nfs access vnode op.
    * For nfs version 2, just return ok. File accesses may fail later.
    * For nfs version 3, use the access rpc to check accessibility. If file modes
    * are changed on the server, accesses might still fail later.
    */
   static int
   nfs_access(struct vop_access_args *ap)
   {
           struct vnode *vp = ap->a_vp;
           int error = 0, i, gotahit;
           u_int32_t mode, wmode, rmode;
           int v34 = NFS_ISV34(vp);
           struct nfsnode *np = VTONFS(vp);
   
           /*
            * Disallow write attempts on filesystems mounted read-only;
            * unless the file is a socket, fifo, or a block or character
            * device resident on the filesystem.
            */
           if ((ap->a_accmode & (VWRITE | VAPPEND
   #ifdef NFS4_ACL_EXTATTR_NAME
               | VWRITE_NAMED_ATTRS | VDELETE_CHILD | VWRITE_ATTRIBUTES |
               VDELETE | VWRITE_ACL | VWRITE_OWNER
   #endif
               )) != 0 && (vp->v_mount->mnt_flag & MNT_RDONLY) != 0) {
                   switch (vp->v_type) {
                   case VREG:
                   case VDIR:
                   case VLNK:
                           return (EROFS);
                   default:
                           break;
                   }
           }
           /*
            * For nfs v3 or v4, check to see if we have done this recently, and if
            * so return our cached result instead of making an ACCESS call.
            * If not, do an access rpc, otherwise you are stuck emulating
            * ufs_access() locally using the vattr. This may not be correct,
            * since the server may apply other access criteria such as
            * client uid-->server uid mapping that we do not know about.
            */
           if (v34) {
                   if (ap->a_accmode & VREAD)
                           mode = NFSACCESS_READ;
                   else
                           mode = 0;
                   if (vp->v_type != VDIR) {
                           if (ap->a_accmode & VWRITE)
                                   mode |= (NFSACCESS_MODIFY | NFSACCESS_EXTEND);
                           if (ap->a_accmode & VAPPEND)
                                   mode |= NFSACCESS_EXTEND;
                           if (ap->a_accmode & VEXEC)
                                   mode |= NFSACCESS_EXECUTE;
   #ifdef NFS4_ACL_EXTATTR_NAME
                           if (ap->a_accmode & VDELETE)
                                   mode |= NFSACCESS_DELETE;
   #endif
                   } else {
                           if (ap->a_accmode & VWRITE)
                                   mode |= (NFSACCESS_MODIFY | NFSACCESS_EXTEND);
                           if (ap->a_accmode & VAPPEND)
                                   mode |= NFSACCESS_EXTEND;
                           if (ap->a_accmode & VEXEC)
                                   mode |= NFSACCESS_LOOKUP;
   #ifdef NFS4_ACL_EXTATTR_NAME
                           if (ap->a_accmode & VDELETE)
                                   mode |= NFSACCESS_DELETE;
                           if (ap->a_accmode & VDELETE_CHILD)
                                   mode |= NFSACCESS_MODIFY;
   #endif
                   }
                   /* XXX safety belt, only make blanket request if caching */
                   if (nfsaccess_cache_timeout > 0) {
                           wmode = NFSACCESS_READ | NFSACCESS_MODIFY |
                                   NFSACCESS_EXTEND | NFSACCESS_EXECUTE |
                                   NFSACCESS_DELETE | NFSACCESS_LOOKUP;
                   } else {
                           wmode = mode;
                   }
   
                   /*
                    * Does our cached result allow us to give a definite yes to
                    * this request?
                    */
                   gotahit = 0;
                   mtx_lock(&np->n_mtx);
                   for (i = 0; i < NFS_ACCESSCACHESIZE; i++) {
                           if (ap->a_cred->cr_uid == np->n_accesscache[i].uid) {
                               if (time_second < (np->n_accesscache[i].stamp
                                   + nfsaccess_cache_timeout) &&
                                   (np->n_accesscache[i].mode & mode) == mode) {
                                   NFSINCRGLOBAL(newnfsstats.accesscache_hits);
                                   gotahit = 1;
                               }
                               break;
                           }
                   }
                   mtx_unlock(&np->n_mtx);
                   if (gotahit == 0) {
                           /*
                            * Either a no, or a don't know.  Go to the wire.
                            */
                           NFSINCRGLOBAL(newnfsstats.accesscache_misses);
                           error = nfs34_access_otw(vp, wmode, ap->a_td,
                               ap->a_cred, &rmode);
                           if (!error &&
                               (rmode & mode) != mode)
                                   error = EACCES;
                   }
                   return (error);
           } else {
                   if ((error = nfsspec_access(ap)) != 0) {
                           return (error);
                   }
                   /*
                    * Attempt to prevent a mapped root from accessing a file
                    * which it shouldn't.  We try to read a byte from the file
                    * if the user is root and the file is not zero length.
                    * After calling nfsspec_access, we should have the correct
                    * file size cached.
                    */
                   mtx_lock(&np->n_mtx);
                   if (ap->a_cred->cr_uid == 0 && (ap->a_accmode & VREAD)
                       && VTONFS(vp)->n_size > 0) {
                           struct iovec aiov;
                           struct uio auio;
                           char buf[1];
   
                           mtx_unlock(&np->n_mtx);
                           aiov.iov_base = buf;
                           aiov.iov_len = 1;
                           auio.uio_iov = &aiov;
                           auio.uio_iovcnt = 1;
                           auio.uio_offset = 0;
                           auio.uio_resid = 1;
                           auio.uio_segflg = UIO_SYSSPACE;
                           auio.uio_rw = UIO_READ;
                           auio.uio_td = ap->a_td;
   
                           if (vp->v_type == VREG)
                                   error = ncl_readrpc(vp, &auio, ap->a_cred);
                           else if (vp->v_type == VDIR) {
                                   char* bp;
                                   bp = malloc(NFS_DIRBLKSIZ, M_TEMP, M_WAITOK);
                                   aiov.iov_base = bp;
                                   aiov.iov_len = auio.uio_resid = NFS_DIRBLKSIZ;
                                   error = ncl_readdirrpc(vp, &auio, ap->a_cred,
                                       ap->a_td);
                                   free(bp, M_TEMP);
                           } else if (vp->v_type == VLNK)
                                   error = ncl_readlinkrpc(vp, &auio, ap->a_cred);
                           else
                                   error = EACCES;
                   } else
                           mtx_unlock(&np->n_mtx);
                   return (error);
           }
   }
   
   
   /*
    * nfs open vnode op
    * Check to see if the type is ok
    * and that deletion is not in progress.
    * For paged in text files, you will need to flush the page cache
    * if consistency is lost.
    */
   /* ARGSUSED */
   static int
   nfs_open(struct vop_open_args *ap)
   {
           struct vnode *vp = ap->a_vp;
           struct nfsnode *np = VTONFS(vp);
           struct vattr vattr;
           int error;
           int fmode = ap->a_mode;
   
           if (vp->v_type != VREG && vp->v_type != VDIR && vp->v_type != VLNK)
                   return (EOPNOTSUPP);
   
           /*
            * For NFSv4, we need to do the Open Op before cache validation,
            * so that we conform to RFC3530 Sec. 9.3.1.
            */
           if (NFS_ISV4(vp)) {
                   error = nfsrpc_open(vp, fmode, ap->a_cred, ap->a_td);
                   if (error) {
                           error = nfscl_maperr(ap->a_td, error, (uid_t)0,
                               (gid_t)0);
                           return (error);
                   }
           }
   
           /*
            * Now, if this Open will be doing reading, re-validate/flush the
            * cache, so that Close/Open coherency is maintained.
            */
           if ((fmode & FREAD) && (!NFS_ISV4(vp) || nfscl_mustflush(vp))) {
                   mtx_lock(&np->n_mtx);
                   if (np->n_flag & NMODIFIED) {
                           mtx_unlock(&np->n_mtx);                 
                           error = ncl_vinvalbuf(vp, V_SAVE, ap->a_td, 1);
                           if (error == EINTR || error == EIO) {
                                   if (NFS_ISV4(vp))
                                           (void) nfsrpc_close(vp, 0, ap->a_td);
                                   return (error);
                           }
                           np->n_attrstamp = 0;
                           if (vp->v_type == VDIR)
                                   np->n_direofoffset = 0;
                           error = VOP_GETATTR(vp, &vattr, ap->a_cred);
                           if (error) {
                                   if (NFS_ISV4(vp))
                                           (void) nfsrpc_close(vp, 0, ap->a_td);
                                   return (error);
                           }
                           mtx_lock(&np->n_mtx);
                           np->n_mtime = vattr.va_mtime;
                           if (NFS_ISV4(vp))
                                   np->n_change = vattr.va_filerev;
                           mtx_unlock(&np->n_mtx);
                   } else {
                           struct thread *td = curthread;
           
                           if (np->n_ac_ts_syscalls != td->td_syscalls ||
                               np->n_ac_ts_tid != td->td_tid || 
                               td->td_proc == NULL ||
                               np->n_ac_ts_pid != td->td_proc->p_pid) {
                                   np->n_attrstamp = 0;
                           }
                           mtx_unlock(&np->n_mtx);                                         
                           error = VOP_GETATTR(vp, &vattr, ap->a_cred);
                           if (error) {
                                   if (NFS_ISV4(vp))
                                           (void) nfsrpc_close(vp, 0, ap->a_td);
                                   return (error);
                           }
                           mtx_lock(&np->n_mtx);
                           if ((NFS_ISV4(vp) && np->n_change != vattr.va_filerev) ||
                               NFS_TIMESPEC_COMPARE(&np->n_mtime, &vattr.va_mtime)) {
                                   if (vp->v_type == VDIR)
                                           np->n_direofoffset = 0;
                                   mtx_unlock(&np->n_mtx);
                                   error = ncl_vinvalbuf(vp, V_SAVE, ap->a_td, 1);
                                   if (error == EINTR || error == EIO) {
                                           if (NFS_ISV4(vp))
                                                   (void) nfsrpc_close(vp, 0,
                                                       ap->a_td);
                                           return (error);
                                   }
                                   mtx_lock(&np->n_mtx);
                                   np->n_mtime = vattr.va_mtime;
                                   if (NFS_ISV4(vp))
                                           np->n_change = vattr.va_filerev;
                           }
                           mtx_unlock(&np->n_mtx);
                   }
           }
   
           /*
            * If the object has >= 1 O_DIRECT active opens, we disable caching.
            */
           if (newnfs_directio_enable && (fmode & O_DIRECT) && (vp->v_type == VREG)) {
                   if (np->n_directio_opens == 0) {
                           error = ncl_vinvalbuf(vp, V_SAVE, ap->a_td, 1);
                           if (error) {
                                   if (NFS_ISV4(vp))
                                           (void) nfsrpc_close(vp, 0, ap->a_td);
                                   return (error);
                           }
                           mtx_lock(&np->n_mtx);
                           np->n_flag |= NNONCACHE;
                   } else {
                           mtx_lock(&np->n_mtx);
                   }
                   np->n_directio_opens++;
                   mtx_unlock(&np->n_mtx);
           }
           vnode_create_vobject(vp, vattr.va_size, ap->a_td);
           return (0);
   }
   
   /*
    * nfs close vnode op
    * What an NFS client should do upon close after writing is a debatable issue.
    * Most NFS clients push delayed writes to the server upon close, basically for
    * two reasons:
    * 1 - So that any write errors may be reported back to the client process
    *     doing the close system call. By far the two most likely errors are
    *     NFSERR_NOSPC and NFSERR_DQUOT to indicate space allocation failure.
    * 2 - To put a worst case upper bound on cache inconsistency between
    *     multiple clients for the file.
    * There is also a consistency problem for Version 2 of the protocol w.r.t.
    * not being able to tell if other clients are writing a file concurrently,
    * since there is no way of knowing if the changed modify time in the reply
    * is only due to the write for this client.
    * (NFS Version 3 provides weak cache consistency data in the reply that
    *  should be sufficient to detect and handle this case.)
    *
    * The current code does the following:
    * for NFS Version 2 - play it safe and flush/invalidate all dirty buffers
    * for NFS Version 3 - flush dirty buffers to the server but don't invalidate
    *                     or commit them (this satisfies 1 and 2 except for the
    *                     case where the server crashes after this close but
    *                     before the commit RPC, which is felt to be "good
    *                     enough". Changing the last argument to ncl_flush() to
    *                     a 1 would force a commit operation, if it is felt a
    *                     commit is necessary now.
    * for NFS Version 4 - flush the dirty buffers and commit them, if
    *                     nfscl_mustflush() says this is necessary.
    *                     It is necessary if there is no write delegation held,
    *                     in order to satisfy open/close coherency.
    *                     If the file isn't cached on local stable storage,
    *                     it may be necessary in order to detect "out of space"
    *                     errors from the server, if the write delegation
    *                     issued by the server doesn't allow the file to grow.
    */
   /* ARGSUSED */
   static int
   nfs_close(struct vop_close_args *ap)
   {
           struct vnode *vp = ap->a_vp;
           struct nfsnode *np = VTONFS(vp);
           struct nfsvattr nfsva;
           struct ucred *cred;
           int error = 0, ret, localcred = 0;
           int fmode = ap->a_fflag;
   
           if ((vp->v_mount->mnt_kern_flag & MNTK_UNMOUNTF))
                   return (0);
           /*
            * During shutdown, a_cred isn't valid, so just use root.
            */
           if (ap->a_cred == NOCRED) {
                   cred = newnfs_getcred();
                   localcred = 1;
           } else {
                   cred = ap->a_cred;
           }
           if (vp->v_type == VREG) {
               /*
                * Examine and clean dirty pages, regardless of NMODIFIED.
                * This closes a major hole in close-to-open consistency.
                * We want to push out all dirty pages (and buffers) on
                * close, regardless of whether they were dirtied by
                * mmap'ed writes or via write().
                */
               if (nfs_clean_pages_on_close && vp->v_object) {
                   VM_OBJECT_LOCK(vp->v_object);
                   vm_object_page_clean(vp->v_object, 0, 0, 0);
                   VM_OBJECT_UNLOCK(vp->v_object);
               }
               mtx_lock(&np->n_mtx);
               if (np->n_flag & NMODIFIED) {
                   mtx_unlock(&np->n_mtx);
                   if (NFS_ISV3(vp)) {
                       /*
                        * Under NFSv3 we have dirty buffers to dispose of.  We
                        * must flush them to the NFS server.  We have the option
                        * of waiting all the way through the commit rpc or just
                        * waiting for the initial write.  The default is to only
                        * wait through the initial write so the data is in the
                        * server's cache, which is roughly similar to the state
                        * a standard disk subsystem leaves the file in on close().
                        *
                        * We cannot clear the NMODIFIED bit in np->n_flag due to
                        * potential races with other processes, and certainly
                        * cannot clear it if we don't commit.
                        * These races occur when there is no longer the old
                        * traditional vnode locking implemented for Vnode Ops.
                        */
                       int cm = newnfs_commit_on_close ? 1 : 0;
                       error = ncl_flush(vp, MNT_WAIT, cred, ap->a_td, cm);
                       /* np->n_flag &= ~NMODIFIED; */
                   } else if (NFS_ISV4(vp)) { 
                           if (nfscl_mustflush(vp)) {
                                   int cm = newnfs_commit_on_close ? 1 : 0;
                                   error = ncl_flush(vp, MNT_WAIT, cred, ap->a_td,
                                       cm);
                                   /*
                                    * as above w.r.t races when clearing
                                    * NMODIFIED.
                                    * np->n_flag &= ~NMODIFIED;
                                    */
                           }
                   } else
                       error = ncl_vinvalbuf(vp, V_SAVE, ap->a_td, 1);
                   mtx_lock(&np->n_mtx);
               }
               /* 
                * Invalidate the attribute cache in all cases.
                * An open is going to fetch fresh attrs any way, other procs
                * on this node that have file open will be forced to do an 
                * otw attr fetch, but this is safe.
                * --> A user found that their RPC count dropped by 20% when
                *     this was commented out and I can't see any requirement
                *     for it, so I've disabled it when negative lookups are
                *     enabled. (What does this have to do with negative lookup
                *     caching? Well nothing, except it was reported by the
                *     same user that needed negative lookup caching and I wanted
                *     there to be a way to disable it via sysctl to see if it
                *     is the cause of some caching/coherency issue that might
                *     crop up.)
                */
               if (newnfs_neglookup_enable == 0)
                       np->n_attrstamp = 0;
               if (np->n_flag & NWRITEERR) {
                   np->n_flag &= ~NWRITEERR;
                   error = np->n_error;
               }
               mtx_unlock(&np->n_mtx);
           }
   
           if (NFS_ISV4(vp)) {
                   /*
                    * Get attributes so "change" is up to date.
                    */
                   if (!error) {
                           ret = nfsrpc_getattr(vp, cred, ap->a_td, &nfsva,
                               NULL);
                           if (!ret) {
                                   np->n_change = nfsva.na_filerev;
                                   (void) nfscl_loadattrcache(&vp, &nfsva, NULL,
                                       NULL, 0, 0);
                           }
                   }
   
                   /*
                    * and do the close.
                    */
                   ret = nfsrpc_close(vp, 0, ap->a_td);
                   if (!error && ret)
                           error = ret;
                   if (error)
                           error = nfscl_maperr(ap->a_td, error, (uid_t)0,
                               (gid_t)0);
           }
           if (newnfs_directio_enable)
                   KASSERT((np->n_directio_asyncwr == 0),
                           ("nfs_close: dirty unflushed (%d) directio buffers\n",
                            np->n_directio_asyncwr));
           if (newnfs_directio_enable && (fmode & O_DIRECT) && (vp->v_type == VREG)) {
                   mtx_lock(&np->n_mtx);
                   KASSERT((np->n_directio_opens > 0), 
                           ("nfs_close: unexpectedly value (0) of n_directio_opens\n"));
                   np->n_directio_opens--;
                   if (np->n_directio_opens == 0)
                           np->n_flag &= ~NNONCACHE;
                   mtx_unlock(&np->n_mtx);
           }
           if (localcred)
                   NFSFREECRED(cred);
           return (error);
   }
   
   /*
    * nfs getattr call from vfs.
    */
   static int
   nfs_getattr(struct vop_getattr_args *ap)
   {
           struct vnode *vp = ap->a_vp;
           struct thread *td = curthread;  /* XXX */
           struct nfsnode *np = VTONFS(vp);
           int error = 0;
           struct nfsvattr nfsva;
           struct vattr *vap = ap->a_vap;
           struct vattr vattr;
   
           /*
            * Update local times for special files.
            */
           mtx_lock(&np->n_mtx);
           if (np->n_flag & (NACC | NUPD))
                   np->n_flag |= NCHG;
           mtx_unlock(&np->n_mtx);
           /*
            * First look in the cache.
            */
           if (ncl_getattrcache(vp, &vattr) == 0) {
                   vap->va_type = vattr.va_type;
                   vap->va_mode = vattr.va_mode;
                   vap->va_nlink = vattr.va_nlink;
                   vap->va_uid = vattr.va_uid;
                   vap->va_gid = vattr.va_gid;
                   vap->va_fsid = vattr.va_fsid;
                   vap->va_fileid = vattr.va_fileid;
                   vap->va_size = vattr.va_size;
                   vap->va_blocksize = vattr.va_blocksize;
                   vap->va_atime = vattr.va_atime;
                   vap->va_mtime = vattr.va_mtime;
                   vap->va_ctime = vattr.va_ctime;
                   vap->va_gen = vattr.va_gen;
                   vap->va_flags = vattr.va_flags;
                   vap->va_rdev = vattr.va_rdev;
                   vap->va_bytes = vattr.va_bytes;
                   vap->va_filerev = vattr.va_filerev;
                   /*
                    * Get the local modify time for the case of a write
                    * delegation.
                    */
                   nfscl_deleggetmodtime(vp, &vap->va_mtime);
                   return (0);
           }
   
           if (NFS_ISV34(vp) && nfs_prime_access_cache &&
               nfsaccess_cache_timeout > 0) {
                   NFSINCRGLOBAL(newnfsstats.accesscache_misses);
                   nfs34_access_otw(vp, NFSACCESS_ALL, td, ap->a_cred, NULL);
                   if (ncl_getattrcache(vp, ap->a_vap) == 0) {
                           nfscl_deleggetmodtime(vp, &ap->a_vap->va_mtime);
                           return (0);
                   }
           }
           error = nfsrpc_getattr(vp, ap->a_cred, td, &nfsva, NULL);
           if (!error)
                   error = nfscl_loadattrcache(&vp, &nfsva, vap, NULL, 0, 0);
           if (!error) {
                   /*
                    * Get the local modify time for the case of a write
                    * delegation.
                    */
                   nfscl_deleggetmodtime(vp, &vap->va_mtime);
           } else if (NFS_ISV4(vp)) {
                   error = nfscl_maperr(td, error, (uid_t)0, (gid_t)0);
           }
           return (error);
   }
   
   /*
    * nfs setattr call.
    */
   static int
   nfs_setattr(struct vop_setattr_args *ap)
   {
           struct vnode *vp = ap->a_vp;
           struct nfsnode *np = VTONFS(vp);
           struct thread *td = curthread;  /* XXX */
           struct vattr *vap = ap->a_vap;
           int error = 0;
           u_quad_t tsize;
   
   #ifndef nolint
           tsize = (u_quad_t)0;
   #endif
   
           /*
            * Setting of flags and marking of atimes are not supported.
            */
           if (vap->va_flags != VNOVAL)
                   return (EOPNOTSUPP);
   
           /*
            * Disallow write attempts if the filesystem is mounted read-only.
            */
           if ((vap->va_flags != VNOVAL || vap->va_uid != (uid_t)VNOVAL ||
               vap->va_gid != (gid_t)VNOVAL || vap->va_atime.tv_sec != VNOVAL ||
               vap->va_mtime.tv_sec != VNOVAL || vap->va_mode != (mode_t)VNOVAL) &&
               (vp->v_mount->mnt_flag & MNT_RDONLY))
                   return (EROFS);
           if (vap->va_size != VNOVAL) {
                   switch (vp->v_type) {
                   case VDIR:
                           return (EISDIR);
                   case VCHR:
                   case VBLK:
                   case VSOCK:
                   case VFIFO:
                           if (vap->va_mtime.tv_sec == VNOVAL &&
                               vap->va_atime.tv_sec == VNOVAL &&
                               vap->va_mode == (mode_t)VNOVAL &&
                               vap->va_uid == (uid_t)VNOVAL &&
                               vap->va_gid == (gid_t)VNOVAL)
                                   return (0);             
                           vap->va_size = VNOVAL;
                           break;
                   default:
                           /*
                            * Disallow write attempts if the filesystem is
                            * mounted read-only.
                            */
                           if (vp->v_mount->mnt_flag & MNT_RDONLY)
                                   return (EROFS);
                           /*
                            *  We run vnode_pager_setsize() early (why?),
                            * we must set np->n_size now to avoid vinvalbuf
                            * V_SAVE races that might setsize a lower
                            * value.
                            */
                           mtx_lock(&np->n_mtx);
                           tsize = np->n_size;
                           mtx_unlock(&np->n_mtx);
                           error = ncl_meta_setsize(vp, ap->a_cred, td,
                               vap->va_size);
                           mtx_lock(&np->n_mtx);
                           if (np->n_flag & NMODIFIED) {
                               tsize = np->n_size;
                               mtx_unlock(&np->n_mtx);
                               if (vap->va_size == 0)
                                   error = ncl_vinvalbuf(vp, 0, td, 1);
                               else
                                   error = ncl_vinvalbuf(vp, V_SAVE, td, 1);
                               if (error) {
                                   vnode_pager_setsize(vp, tsize);
                                   return (error);
                               }
                               /*
                                * Call nfscl_delegmodtime() to set the modify time
                                * locally, as required.
                                */
                               nfscl_delegmodtime(vp);
                           } else
                               mtx_unlock(&np->n_mtx);
                           /*
                            * np->n_size has already been set to vap->va_size
                            * in ncl_meta_setsize(). We must set it again since
                            * nfs_loadattrcache() could be called through
                            * ncl_meta_setsize() and could modify np->n_size.
                            */
                           mtx_lock(&np->n_mtx);
                           np->n_vattr.na_size = np->n_size = vap->va_size;
                           mtx_unlock(&np->n_mtx);
                   };
           } else {
                   mtx_lock(&np->n_mtx);
                   if ((vap->va_mtime.tv_sec != VNOVAL || vap->va_atime.tv_sec != VNOVAL) && 
                       (np->n_flag & NMODIFIED) && vp->v_type == VREG) {
                           mtx_unlock(&np->n_mtx);
                           if ((error = ncl_vinvalbuf(vp, V_SAVE, td, 1)) != 0 &&
                               (error == EINTR || error == EIO))
                                   return (error);
                   } else
                           mtx_unlock(&np->n_mtx);
           }
           error = nfs_setattrrpc(vp, vap, ap->a_cred, td);
           if (error && vap->va_size != VNOVAL) {
                   mtx_lock(&np->n_mtx);
                   np->n_size = np->n_vattr.na_size = tsize;
                   vnode_pager_setsize(vp, tsize);
                   mtx_unlock(&np->n_mtx);
           }
           return (error);
   }
   
   /*
    * Do an nfs setattr rpc.
    */
   static int
   nfs_setattrrpc(struct vnode *vp, struct vattr *vap, struct ucred *cred,
       struct thread *td)
   {
           struct nfsnode *np = VTONFS(vp);
           int error, ret, attrflag, i;
           struct nfsvattr nfsva;
   
           if (NFS_ISV34(vp)) {
                   mtx_lock(&np->n_mtx);
                   for (i = 0; i < NFS_ACCESSCACHESIZE; i++)
                           np->n_accesscache[i].stamp = 0;
                   np->n_flag |= NDELEGMOD;
                   mtx_unlock(&np->n_mtx);
           }
           error = nfsrpc_setattr(vp, vap, NULL, cred, td, &nfsva, &attrflag,
               NULL);
           if (attrflag) {
                   ret = nfscl_loadattrcache(&vp, &nfsva, NULL, NULL, 0, 1);
                   if (ret && !error)
                           error = ret;
           }
           if (error && NFS_ISV4(vp))
                   error = nfscl_maperr(td, error, vap->va_uid, vap->va_gid);
           return (error);
   }
   
   /*
    * nfs lookup call, one step at a time...
    * First look in cache
    * If not found, unlock the directory nfsnode and do the rpc
    */
   static int
   nfs_lookup(struct vop_lookup_args *ap)
   {
           struct componentname *cnp = ap->a_cnp;
           struct vnode *dvp = ap->a_dvp;
          struct vnode **vpp = ap->a_vpp;
          struct mount *mp = dvp->v_mount;
          int flags = cnp->cn_flags;
          struct vnode *newvp;
          struct nfsmount *nmp;
          struct nfsnode *np;
          int error = 0, attrflag, dattrflag, ltype;
          struct thread *td = cnp->cn_thread;
          struct nfsfh *nfhp;
          struct nfsvattr dnfsva, nfsva;
          
          *vpp = NULLVP;
          if ((flags & ISLASTCN) && (mp->mnt_flag & MNT_RDONLY) &&
              (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
                  return (EROFS);
          if (dvp->v_type != VDIR)
                  return (ENOTDIR);
          nmp = VFSTONFS(mp);
          np = VTONFS(dvp);
  
          /* For NFSv4, wait until any remove is done. */
          mtx_lock(&np->n_mtx);
          while (NFSHASNFSV4(nmp) && (np->n_flag & NREMOVEINPROG)) {
                  np->n_flag |= NREMOVEWANT;
                  (void) msleep((caddr_t)np, &np->n_mtx, PZERO, "nfslkup", 0);
          }
          mtx_unlock(&np->n_mtx);
  
          if ((error = VOP_ACCESS(dvp, VEXEC, cnp->cn_cred, td)) != 0)
                  return (error);
          if ((error = cache_lookup(dvp, vpp, cnp)) &&
              (error != ENOENT || newnfs_neglookup_enable != 0)) {
                  struct vattr vattr;
  
                  if (error == ENOENT) {
                          if (!VOP_GETATTR(dvp, &vattr, cnp->cn_cred) &&
                              vattr.va_mtime.tv_sec == np->n_dmtime) {
                               NFSINCRGLOBAL(newnfsstats.lookupcache_hits);
                                  return (ENOENT);
                          }
                          cache_purge_negative(dvp);
                          np->n_dmtime = 0;
                  } else {
                          newvp = *vpp;
                          if (nfscl_nodeleg(newvp, 0) == 0 ||
                              (!VOP_GETATTR(newvp, &vattr, cnp->cn_cred) &&
                               vattr.va_ctime.tv_sec==VTONFS(newvp)->n_ctime)) {
                               NFSINCRGLOBAL(newnfsstats.lookupcache_hits);
                               if (cnp->cn_nameiop != LOOKUP &&
                                   (flags & ISLASTCN))
                                       cnp->cn_flags |= SAVENAME;
                               return (0);
                          }
                          cache_purge(newvp);
                          if (dvp != newvp)
                                  vput(newvp);
                          else 
                                  vrele(newvp);
                          *vpp = NULLVP;
                  }
          }
          error = 0;
          newvp = NULLVP;
          NFSINCRGLOBAL(newnfsstats.lookupcache_misses);
          error = nfsrpc_lookup(dvp, cnp->cn_nameptr, cnp->cn_namelen,
              cnp->cn_cred, td, &dnfsva, &nfsva, &nfhp, &attrflag, &dattrflag,
              NULL);
          if (dattrflag)
                  (void) nfscl_loadattrcache(&dvp, &dnfsva, NULL, NULL, 0, 1);
          if (error) {
                  if (newnfs_neglookup_enable != 0 &&
                      error == ENOENT && (cnp->cn_flags & MAKEENTRY) &&
                      cnp->cn_nameiop != CREATE) {
                          if (np->n_dmtime == 0)
                                  np->n_dmtime = np->n_vattr.na_mtime.tv_sec;
                          cache_enter(dvp, NULL, cnp);
                  }
                  if (newvp != NULLVP) {
                          vput(newvp);
                          *vpp = NULLVP;
                  }
                  if ((cnp->cn_nameiop == CREATE || cnp->cn_nameiop == RENAME) &&
                      (flags & ISLASTCN) && error == ENOENT) {
                          if (mp->mnt_flag & MNT_RDONLY)
                                  error = EROFS;
                          else
                                  error = EJUSTRETURN;
                  }
                  if (cnp->cn_nameiop != LOOKUP && (flags & ISLASTCN))
                          cnp->cn_flags |= SAVENAME;
                  if (NFS_ISV4(dvp))
                          error = nfscl_maperr(td, error, (uid_t)0, (gid_t)0);
                  return (error);
          }
  
          /*
           * Handle RENAME case...
           */
          if (cnp->cn_nameiop == RENAME && (flags & ISLASTCN)) {
                  if (NFS_CMPFH(np, nfhp->nfh_fh, nfhp->nfh_len)) {
                          FREE((caddr_t)nfhp, M_NFSFH);
                          return (EISDIR);
                  }
                  error = nfscl_nget(mp, dvp, nfhp, cnp, td, &np, NULL);
                  if (error)
                          return (error);
                  newvp = NFSTOV(np);
                  if (attrflag)
                          (void) nfscl_loadattrcache(&newvp, &nfsva, NULL, NULL,
                              0, 1);
                  *vpp = newvp;
                  cnp->cn_flags |= SAVENAME;
                  return (0);
          }
  
          if (flags & ISDOTDOT) {
                  ltype = VOP_ISLOCKED(dvp);
                  error = vfs_busy(mp, MBF_NOWAIT);
                  if (error != 0) {
                          vfs_ref(mp);
                          VOP_UNLOCK(dvp, 0);
                          error = vfs_busy(mp, 0);
                          vn_lock(dvp, ltype | LK_RETRY);
                          vfs_rel(mp);
                          if (error == 0 && (dvp->v_iflag & VI_DOOMED)) {
                                  vfs_unbusy(mp);
                                  error = ENOENT;
                          }
                          if (error != 0)
                                  return (error);
                  }
                  VOP_UNLOCK(dvp, 0);
                  error = nfscl_nget(mp, dvp, nfhp, cnp, td, &np, NULL);
                  if (error == 0)
                          newvp = NFSTOV(np);
                  vfs_unbusy(mp);
                  if (newvp != dvp)
                          vn_lock(dvp, ltype | LK_RETRY);
                  if (dvp->v_iflag & VI_DOOMED) {
                          if (error == 0) {
                                  if (newvp == dvp)
                                          vrele(newvp);
                                  else
                                          vput(newvp);
                          }
                          error = ENOENT;
                  }
                  if (error != 0)
                          return (error);
                  if (attrflag)
                          (void) nfscl_loadattrcache(&newvp, &nfsva, NULL, NULL,
                              0, 1);
          } else if (NFS_CMPFH(np, nfhp->nfh_fh, nfhp->nfh_len)) {
                  FREE((caddr_t)nfhp, M_NFSFH);
                  VREF(dvp);
                  newvp = dvp;
                  if (attrflag)
                          (void) nfscl_loadattrcache(&newvp, &nfsva, NULL, NULL,
                              0, 1);
          } else {
                  error = nfscl_nget(mp, dvp, nfhp, cnp, td, &np, NULL);
                  if (error)
                          return (error);
                  newvp = NFSTOV(np);
                  if (attrflag)
                          (void) nfscl_loadattrcache(&newvp, &nfsva, NULL, NULL,
                              0, 1);
          }
          if (cnp->cn_nameiop != LOOKUP && (flags & ISLASTCN))
                  cnp->cn_flags |= SAVENAME;
          if ((cnp->cn_flags & MAKEENTRY) &&
              (cnp->cn_nameiop != DELETE || !(flags & ISLASTCN))) {
                  np->n_ctime = np->n_vattr.na_vattr.va_ctime.tv_sec;
                  cache_enter(dvp, newvp, cnp);
          }
          *vpp = newvp;
          return (0);
  }
  
  /*
   * nfs read call.
   * Just call ncl_bioread() to do the work.
   */
  static int
  nfs_read(struct vop_read_args *ap)
  {
          struct vnode *vp = ap->a_vp;
  
          switch (vp->v_type) {
          case VREG:
                  return (ncl_bioread(vp, ap->a_uio, ap->a_ioflag, ap->a_cred));
          case VDIR:
                  return (EISDIR);
          default:
                  return (EOPNOTSUPP);
          }
  }
  
  /*
   * nfs readlink call
   */
  static int
  nfs_readlink(struct vop_readlink_args *ap)
  {
          struct vnode *vp = ap->a_vp;
  
          if (vp->v_type != VLNK)
                  return (EINVAL);
          return (ncl_bioread(vp, ap->a_uio, 0, ap->a_cred));
  }
  
  /*
   * Do a readlink rpc.
   * Called by ncl_doio() from below the buffer cache.
   */
  int
  ncl_readlinkrpc(struct vnode *vp, struct uio *uiop, struct ucred *cred)
  {
          int error, ret, attrflag;
          struct nfsvattr nfsva;
  
          error = nfsrpc_readlink(vp, uiop, cred, uiop->uio_td, &nfsva,
              &attrflag, NULL);
          if (attrflag) {
                  ret = nfscl_loadattrcache(&vp, &nfsva, NULL, NULL, 0, 1);
                  if (ret && !error)
                          error = ret;
          }
          if (error && NFS_ISV4(vp))
                  error = nfscl_maperr(uiop->uio_td, error, (uid_t)0, (gid_t)0);
          return (error);
  }
  
  /*
   * nfs read rpc call
   * Ditto above
   */
  int
  ncl_readrpc(struct vnode *vp, struct uio *uiop, struct ucred *cred)
  {
          int error, ret, attrflag;
          struct nfsvattr nfsva;
  
          error = nfsrpc_read(vp, uiop, cred, uiop->uio_td, &nfsva, &attrflag,
              NULL);
          if (attrflag) {
                  ret = nfscl_loadattrcache(&vp, &nfsva, NULL, NULL, 0, 1);
                  if (ret && !error)
                          error = ret;
          }
          if (error && NFS_ISV4(vp))
                  error = nfscl_maperr(uiop->uio_td, error, (uid_t)0, (gid_t)0);
          return (error);
  }
  
  /*
   * nfs write call
   */
  int
  ncl_writerpc(struct vnode *vp, struct uio *uiop, struct ucred *cred,
               int *iomode, int *must_commit)
  {
          struct nfsvattr nfsva;
          int error = 0, attrflag, ret;
          u_char verf[NFSX_VERF];
          struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  
          *must_commit = 0;
          error = nfsrpc_write(vp, uiop, iomode, verf, cred,
              uiop->uio_td, &nfsva, &attrflag, NULL);
          NFSLOCKMNT(nmp);
          if (!error && NFSHASWRITEVERF(nmp) &&
              NFSBCMP(verf, nmp->nm_verf, NFSX_VERF)) {
                  *must_commit = 1;
                  NFSBCOPY(verf, nmp->nm_verf, NFSX_VERF);
          }
          NFSUNLOCKMNT(nmp);
          if (attrflag) {
                  if (VTONFS(vp)->n_flag & ND_NFSV4)
                          ret = nfscl_loadattrcache(&vp, &nfsva, NULL, NULL, 1,
                              1);
                  else
                          ret = nfscl_loadattrcache(&vp, &nfsva, NULL, NULL, 0,
                              1);
                  if (ret && !error)
                          error = ret;
          }
          if (vp->v_mount->mnt_kern_flag & MNTK_ASYNC)
                  *iomode = NFSWRITE_FILESYNC;
          if (error && NFS_ISV4(vp))
                  error = nfscl_maperr(uiop->uio_td, error, (uid_t)0, (gid_t)0);
          return (error);
  }
  
  /*
   * nfs mknod rpc
   * For NFS v2 this is a kludge. Use a create rpc but with the IFMT bits of the
   * mode set to specify the file type and the size field for rdev.
   */
  static int
  nfs_mknodrpc(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
      struct vattr *vap)
  {
          struct nfsvattr nfsva, dnfsva;
          struct vnode *newvp = NULL;
          struct nfsnode *np = NULL, *dnp;
          struct nfsfh *nfhp;
          struct vattr vattr;
          int error = 0, attrflag, dattrflag;
          u_int32_t rdev;
  
          if (vap->va_type == VCHR || vap->va_type == VBLK)
                  rdev = vap->va_rdev;
          else if (vap->va_type == VFIFO || vap->va_type == VSOCK)
                  rdev = 0xffffffff;
          else
                  return (EOPNOTSUPP);
          if ((error = VOP_GETATTR(dvp, &vattr, cnp->cn_cred)))
                  return (error);
          error = nfsrpc_mknod(dvp, cnp->cn_nameptr, cnp->cn_namelen, vap,
              rdev, vap->va_type, cnp->cn_cred, cnp->cn_thread, &dnfsva,
              &nfsva, &nfhp, &attrflag, &dattrflag, NULL);
          if (!error) {
                  if (!nfhp)
                          (void) nfsrpc_lookup(dvp, cnp->cn_nameptr,
                              cnp->cn_namelen, cnp->cn_cred, cnp->cn_thread,
                              &dnfsva, &nfsva, &nfhp, &attrflag, &dattrflag,
                              NULL);
                  if (nfhp)
                          error = nfscl_nget(dvp->v_mount, dvp, nfhp, cnp,
                              cnp->cn_thread, &np, NULL);
          }
          if (dattrflag)
                  (void) nfscl_loadattrcache(&dvp, &dnfsva, NULL, NULL, 0, 1);
          if (!error) {
                  newvp = NFSTOV(np);
                  if (attrflag)
                          error = nfscl_loadattrcache(&newvp, &nfsva, NULL, NULL,
                              0, 1);
          }
          if (!error) {
                  if ((cnp->cn_flags & MAKEENTRY))
                          cache_enter(dvp, newvp, cnp);
                  *vpp = newvp;
          } else if (NFS_ISV4(dvp)) {
                  error = nfscl_maperr(cnp->cn_thread, error, vap->va_uid,
                      vap->va_gid);
          }
          dnp = VTONFS(dvp);
          mtx_lock(&dnp->n_mtx);
          dnp->n_flag |= NMODIFIED;
          if (!dattrflag)
                  dnp->n_attrstamp = 0;
          mtx_unlock(&dnp->n_mtx);
          return (error);
  }
  
  /*
   * nfs mknod vop
   * just call nfs_mknodrpc() to do the work.
   */
  /* ARGSUSED */
  static int
  nfs_mknod(struct vop_mknod_args *ap)
  {
          return (nfs_mknodrpc(ap->a_dvp, ap->a_vpp, ap->a_cnp, ap->a_vap));
  }
  
  static u_long create_verf;
  /*
   * nfs file create call
   */
  static int
  nfs_create(struct vop_create_args *ap)
  {
          struct vnode *dvp = ap->a_dvp;
          struct vattr *vap = ap->a_vap;
          struct componentname *cnp = ap->a_cnp;
          struct nfsnode *np = NULL, *dnp;
          struct vnode *newvp = NULL;
          struct nfsmount *nmp;
          struct nfsvattr dnfsva, nfsva;
          struct nfsfh *nfhp;
          nfsquad_t cverf;
          int error = 0, attrflag, dattrflag, fmode = 0;
          struct vattr vattr;
  
          /*
           * Oops, not for me..
           */
          if (vap->va_type == VSOCK)
                  return (nfs_mknodrpc(dvp, ap->a_vpp, cnp, vap));
  
          if ((error = VOP_GETATTR(dvp, &vattr, cnp->cn_cred)))
                  return (error);
          if (vap->va_vaflags & VA_EXCLUSIVE)
                  fmode |= O_EXCL;
          dnp = VTONFS(dvp);
          nmp = VFSTONFS(vnode_mount(dvp));
  again:
          /* For NFSv4, wait until any remove is done. */
          mtx_lock(&dnp->n_mtx);
          while (NFSHASNFSV4(nmp) && (dnp->n_flag & NREMOVEINPROG)) {
                  dnp->n_flag |= NREMOVEWANT;
                  (void) msleep((caddr_t)dnp, &dnp->n_mtx, PZERO, "nfscrt", 0);
          }
          mtx_unlock(&dnp->n_mtx);
  
  #ifdef INET
          CURVNET_SET(CRED_TO_VNET(cnp->cn_cred));
          IN_IFADDR_RLOCK();
          if (!TAILQ_EMPTY(&V_in_ifaddrhead))
                  cverf.lval[0] = IA_SIN(TAILQ_FIRST(&V_in_ifaddrhead))->sin_addr.s_addr;
          else
  #endif
                  cverf.lval[0] = create_verf;
  #ifdef INET
          IN_IFADDR_RUNLOCK();
          CURVNET_RESTORE();
  #endif
          cverf.lval[1] = ++create_verf;
          error = nfsrpc_create(dvp, cnp->cn_nameptr, cnp->cn_namelen,
              vap, cverf, fmode, cnp->cn_cred, cnp->cn_thread, &dnfsva, &nfsva,
              &nfhp, &attrflag, &dattrflag, NULL);
          if (!error) {
                  if (nfhp == NULL)
                          (void) nfsrpc_lookup(dvp, cnp->cn_nameptr,
                              cnp->cn_namelen, cnp->cn_cred, cnp->cn_thread,
                              &dnfsva, &nfsva, &nfhp, &attrflag, &dattrflag,
                              NULL);
                  if (nfhp != NULL)
                          error = nfscl_nget(dvp->v_mount, dvp, nfhp, cnp,
                              cnp->cn_thread, &np, NULL);
          }
          if (dattrflag)
                  (void) nfscl_loadattrcache(&dvp, &dnfsva, NULL, NULL, 0, 1);
          if (!error) {
                  newvp = NFSTOV(np);
                  if (attrflag)
                          error = nfscl_loadattrcache(&newvp, &nfsva, NULL, NULL,
                              0, 1);
          }
          if (error) {
                  if (newvp != NULL) {
                          vrele(newvp);
                          newvp = NULL;
                  }
                  if (NFS_ISV34(dvp) && (fmode & O_EXCL) &&
                      error == NFSERR_NOTSUPP) {
                          fmode &= ~O_EXCL;
                          goto again;
                  }
          } else if (NFS_ISV34(dvp) && (fmode & O_EXCL)) {
                  if (nfscl_checksattr(vap, &nfsva)) {
                          error = nfsrpc_setattr(newvp, vap, NULL, cnp->cn_cred,
                              cnp->cn_thread, &nfsva, &attrflag, NULL);
                          if (error && (vap->va_uid != (uid_t)VNOVAL ||
                              vap->va_gid != (gid_t)VNOVAL)) {
                                  /* try again without setting uid/gid */
                                  vap->va_uid = (uid_t)VNOVAL;
                                  vap->va_gid = (uid_t)VNOVAL;
                                  error = nfsrpc_setattr(newvp, vap, NULL, 
                                      cnp->cn_cred, cnp->cn_thread, &nfsva,
                                      &attrflag, NULL);
                          }
                          if (attrflag)
                                  (void) nfscl_loadattrcache(&newvp, &nfsva, NULL,
                                      NULL, 0, 1);
                  }
          }
          if (!error) {
                  if (cnp->cn_flags & MAKEENTRY)
                          cache_enter(dvp, newvp, cnp);
                  *ap->a_vpp = newvp;
          } else if (NFS_ISV4(dvp)) {
                  error = nfscl_maperr(cnp->cn_thread, error, vap->va_uid,
                      vap->va_gid);
          }
          mtx_lock(&dnp->n_mtx);
          dnp->n_flag |= NMODIFIED;
          if (!dattrflag)
                  dnp->n_attrstamp = 0;
          mtx_unlock(&dnp->n_mtx);
          return (error);
  }
  
  /*
   * nfs file remove call
   * To try and make nfs semantics closer to ufs semantics, a file that has
   * other processes using the vnode is renamed instead of removed and then
   * removed later on the last close.
   * - If v_usecount > 1
   *        If a rename is not already in the works
   *           call nfs_sillyrename() to set it up
   *     else
   *        do the remove rpc
   */
  static int
  nfs_remove(struct vop_remove_args *ap)
  {
          struct vnode *vp = ap->a_vp;
          struct vnode *dvp = ap->a_dvp;
          struct componentname *cnp = ap->a_cnp;
          struct nfsnode *np = VTONFS(vp);
          int error = 0;
          struct vattr vattr;
  
  #ifndef DIAGNOSTIC
          if ((cnp->cn_flags & HASBUF) == 0)
                  panic("nfs_remove: no name");
          if (vrefcnt(vp) < 1)
                  panic("nfs_remove: bad v_usecount");
  #endif
          if (vp->v_type == VDIR)
                  error = EPERM;
          else if (vrefcnt(vp) == 1 || (np->n_sillyrename &&
              VOP_GETATTR(vp, &vattr, cnp->cn_cred) == 0 &&
              vattr.va_nlink > 1)) {
                  /*
                   * Purge the name cache so that the chance of a lookup for
                   * the name succeeding while the remove is in progress is
                   * minimized. Without node locking it can still happen, such
                   * that an I/O op returns ESTALE, but since you get this if
                   * another host removes the file..
                   */
                  cache_purge(vp);
                  /*
                   * throw away biocache buffers, mainly to avoid
                   * unnecessary delayed writes later.
                   */
                  error = ncl_vinvalbuf(vp, 0, cnp->cn_thread, 1);
                  /* Do the rpc */
                  if (error != EINTR && error != EIO)
                          error = nfs_removerpc(dvp, vp, cnp->cn_nameptr,
                              cnp->cn_namelen, cnp->cn_cred, cnp->cn_thread);
                  /*
                   * Kludge City: If the first reply to the remove rpc is lost..
                   *   the reply to the retransmitted request will be ENOENT
                   *   since the file was in fact removed
                   *   Therefore, we cheat and return success.
                   */
                  if (error == ENOENT)
                          error = 0;
          } else if (!np->n_sillyrename)
                  error = nfs_sillyrename(dvp, vp, cnp);
          np->n_attrstamp = 0;
          return (error);
  }
  
  /*
   * nfs file remove rpc called from nfs_inactive
   */
  int
  ncl_removeit(struct sillyrename *sp, struct vnode *vp)
  {
          /*
           * Make sure that the directory vnode is still valid.
           * XXX we should lock sp->s_dvp here.
           */
          if (sp->s_dvp->v_type == VBAD)
                  return (0);
          return (nfs_removerpc(sp->s_dvp, vp, sp->s_name, sp->s_namlen,
              sp->s_cred, NULL));
  }
  
  /*
   * Nfs remove rpc, called from nfs_remove() and ncl_removeit().
   */
  static int
  nfs_removerpc(struct vnode *dvp, struct vnode *vp, char *name,
      int namelen, struct ucred *cred, struct thread *td)
  {
          struct nfsvattr dnfsva;
          struct nfsnode *dnp = VTONFS(dvp);
          int error = 0, dattrflag;
  
          mtx_lock(&dnp->n_mtx);
          dnp->n_flag |= NREMOVEINPROG;
          mtx_unlock(&dnp->n_mtx);
          error = nfsrpc_remove(dvp, name, namelen, vp, cred, td, &dnfsva,
              &dattrflag, NULL);
          mtx_lock(&dnp->n_mtx);
          if ((dnp->n_flag & NREMOVEWANT)) {
                  dnp->n_flag &= ~(NREMOVEWANT | NREMOVEINPROG);
                  mtx_unlock(&dnp->n_mtx);
                  wakeup((caddr_t)dnp);
          } else {
                  dnp->n_flag &= ~NREMOVEINPROG;
                  mtx_unlock(&dnp->n_mtx);
          }
          if (dattrflag)
                  (void) nfscl_loadattrcache(&dvp, &dnfsva, NULL, NULL, 0, 1);
          mtx_lock(&dnp->n_mtx);
          dnp->n_flag |= NMODIFIED;
          if (!dattrflag)
                  dnp->n_attrstamp = 0;
          mtx_unlock(&dnp->n_mtx);
          if (error && NFS_ISV4(dvp))
                  error = nfscl_maperr(td, error, (uid_t)0, (gid_t)0);
          return (error);
  }
  
  /*
   * nfs file rename call
   */
  static int
  nfs_rename(struct vop_rename_args *ap)
  {
          struct vnode *fvp = ap->a_fvp;
          struct vnode *tvp = ap->a_tvp;
          struct vnode *fdvp = ap->a_fdvp;
          struct vnode *tdvp = ap->a_tdvp;
          struct componentname *tcnp = ap->a_tcnp;
          struct componentname *fcnp = ap->a_fcnp;
          struct nfsnode *fnp = VTONFS(ap->a_fvp);
          struct nfsnode *tdnp = VTONFS(ap->a_tdvp);
          struct nfsv4node *newv4 = NULL;
          int error;
  
  #ifndef DIAGNOSTIC
          if ((tcnp->cn_flags & HASBUF) == 0 ||
              (fcnp->cn_flags & HASBUF) == 0)
                  panic("nfs_rename: no name");
  #endif
          /* Check for cross-device rename */
          if ((fvp->v_mount != tdvp->v_mount) ||
              (tvp && (fvp->v_mount != tvp->v_mount))) {
                  error = EXDEV;
                  goto out;
          }
  
          if (fvp == tvp) {
                  ncl_printf("nfs_rename: fvp == tvp (can't happen)\n");
                  error = 0;
                  goto out;
          }
          if ((error = vn_lock(fvp, LK_EXCLUSIVE)))
                  goto out;
  
          /*
           * We have to flush B_DELWRI data prior to renaming
           * the file.  If we don't, the delayed-write buffers
           * can be flushed out later after the file has gone stale
           * under NFSV3.  NFSV2 does not have this problem because
           * ( as far as I can tell ) it flushes dirty buffers more
           * often.
           * 
           * Skip the rename operation if the fsync fails, this can happen
           * due to the server's volume being full, when we pushed out data
           * that was written back to our cache earlier. Not checking for
           * this condition can result in potential (silent) data loss.
           */
          error = VOP_FSYNC(fvp, MNT_WAIT, fcnp->cn_thread);
          VOP_UNLOCK(fvp, 0);
          if (!error && tvp)
                  error = VOP_FSYNC(tvp, MNT_WAIT, tcnp->cn_thread);
          if (error)
                  goto out;
  
          /*
           * If the tvp exists and is in use, sillyrename it before doing the
           * rename of the new file over it.
           * XXX Can't sillyrename a directory.
           */
          if (tvp && vrefcnt(tvp) > 1 && !VTONFS(tvp)->n_sillyrename &&
                  tvp->v_type != VDIR && !nfs_sillyrename(tdvp, tvp, tcnp)) {
                  vput(tvp);
                  tvp = NULL;
          }
  
          error = nfs_renamerpc(fdvp, fvp, fcnp->cn_nameptr, fcnp->cn_namelen,
              tdvp, tvp, tcnp->cn_nameptr, tcnp->cn_namelen, tcnp->cn_cred,
              tcnp->cn_thread);
  
          if (!error) {
                  /*
                   * For NFSv4, check to see if it is the same name and
                   * replace the name, if it is different.
                   */
                  MALLOC(newv4, struct nfsv4node *,
                      sizeof (struct nfsv4node) +
                      tdnp->n_fhp->nfh_len + tcnp->cn_namelen - 1,
                      M_NFSV4NODE, M_WAITOK);
                  mtx_lock(&tdnp->n_mtx);
                  mtx_lock(&fnp->n_mtx);
                  if (fnp->n_v4 != NULL && fvp->v_type == VREG &&
                      (fnp->n_v4->n4_namelen != tcnp->cn_namelen ||
                        NFSBCMP(tcnp->cn_nameptr, NFS4NODENAME(fnp->n_v4),
                        tcnp->cn_namelen) ||
                        tdnp->n_fhp->nfh_len != fnp->n_v4->n4_fhlen ||
                        NFSBCMP(tdnp->n_fhp->nfh_fh, fnp->n_v4->n4_data,
                          tdnp->n_fhp->nfh_len))) {
  #ifdef notdef
  { char nnn[100]; int nnnl;
  nnnl = (tcnp->cn_namelen < 100) ? tcnp->cn_namelen : 99;
  bcopy(tcnp->cn_nameptr, nnn, nnnl);
  nnn[nnnl] = '\0';
  printf("ren replace=%s\n",nnn);
  }
  #endif
                          FREE((caddr_t)fnp->n_v4, M_NFSV4NODE);
                          fnp->n_v4 = newv4;
                          newv4 = NULL;
                          fnp->n_v4->n4_fhlen = tdnp->n_fhp->nfh_len;
                          fnp->n_v4->n4_namelen = tcnp->cn_namelen;
                          NFSBCOPY(tdnp->n_fhp->nfh_fh, fnp->n_v4->n4_data,
                              tdnp->n_fhp->nfh_len);
                          NFSBCOPY(tcnp->cn_nameptr,
                              NFS4NODENAME(fnp->n_v4), tcnp->cn_namelen);
                  }
                  mtx_unlock(&tdnp->n_mtx);
                  mtx_unlock(&fnp->n_mtx);
                  if (newv4 != NULL)
                          FREE((caddr_t)newv4, M_NFSV4NODE);
          }
  
          if (fvp->v_type == VDIR) {
                  if (tvp != NULL && tvp->v_type == VDIR)
                          cache_purge(tdvp);
                  cache_purge(fdvp);
          }
  
  out:
          if (tdvp == tvp)
                  vrele(tdvp);
          else
                  vput(tdvp);
          if (tvp)
                  vput(tvp);
          vrele(fdvp);
          vrele(fvp);
          /*
           * Kludge: Map ENOENT => 0 assuming that it is a reply to a retry.
           */
          if (error == ENOENT)
                  error = 0;
          return (error);
  }
  
  /*
   * nfs file rename rpc called from nfs_remove() above
   */
  static int
  nfs_renameit(struct vnode *sdvp, struct vnode *svp, struct componentname *scnp,
      struct sillyrename *sp)
  {
  
          return (nfs_renamerpc(sdvp, svp, scnp->cn_nameptr, scnp->cn_namelen,
              sdvp, NULL, sp->s_name, sp->s_namlen, scnp->cn_cred,
              scnp->cn_thread));
  }
  
  /*
   * Do an nfs rename rpc. Called from nfs_rename() and nfs_renameit().
   */
  static int
  nfs_renamerpc(struct vnode *fdvp, struct vnode *fvp, char *fnameptr,
      int fnamelen, struct vnode *tdvp, struct vnode *tvp, char *tnameptr,
      int tnamelen, struct ucred *cred, struct thread *td)
  {
          struct nfsvattr fnfsva, tnfsva;
          struct nfsnode *fdnp = VTONFS(fdvp);
          struct nfsnode *tdnp = VTONFS(tdvp);
          int error = 0, fattrflag, tattrflag;
  
          error = nfsrpc_rename(fdvp, fvp, fnameptr, fnamelen, tdvp, tvp,
              tnameptr, tnamelen, cred, td, &fnfsva, &tnfsva, &fattrflag,
              &tattrflag, NULL, NULL);
          mtx_lock(&fdnp->n_mtx);
          fdnp->n_flag |= NMODIFIED;
          mtx_unlock(&fdnp->n_mtx);
          mtx_lock(&tdnp->n_mtx);
          tdnp->n_flag |= NMODIFIED;
          mtx_unlock(&tdnp->n_mtx);
          if (fattrflag)
                  (void) nfscl_loadattrcache(&fdvp, &fnfsva, NULL, NULL, 0, 1);
          else
                  fdnp->n_attrstamp = 0;
          if (tattrflag)
                  (void) nfscl_loadattrcache(&tdvp, &tnfsva, NULL, NULL, 0, 1);
          else
                  tdnp->n_attrstamp = 0;
          if (error && NFS_ISV4(fdvp))
                  error = nfscl_maperr(td, error, (uid_t)0, (gid_t)0);
          return (error);
  }
  
  /*
   * nfs hard link create call
   */
  static int
  nfs_link(struct vop_link_args *ap)
  {
          struct vnode *vp = ap->a_vp;
          struct vnode *tdvp = ap->a_tdvp;
          struct componentname *cnp = ap->a_cnp;
          struct nfsnode *tdnp;
          struct nfsvattr nfsva, dnfsva;
          int error = 0, attrflag, dattrflag;
  
          if (vp->v_mount != tdvp->v_mount) {
                  return (EXDEV);
          }
  
          /*
           * Push all writes to the server, so that the attribute cache
           * doesn't get "out of sync" with the server.
           * XXX There should be a better way!
           */
          VOP_FSYNC(vp, MNT_WAIT, cnp->cn_thread);
  
          error = nfsrpc_link(tdvp, vp, cnp->cn_nameptr, cnp->cn_namelen,
              cnp->cn_cred, cnp->cn_thread, &dnfsva, &nfsva, &attrflag,
              &dattrflag, NULL);
          tdnp = VTONFS(tdvp);
          mtx_lock(&tdnp->n_mtx);
          tdnp->n_flag |= NMODIFIED;
          mtx_unlock(&tdnp->n_mtx);
          if (attrflag)
                  (void) nfscl_loadattrcache(&vp, &nfsva, NULL, NULL, 0, 1);
          else
                  VTONFS(vp)->n_attrstamp = 0;
          if (dattrflag)
                  (void) nfscl_loadattrcache(&tdvp, &dnfsva, NULL, NULL, 0, 1);
          else
                  tdnp->n_attrstamp = 0;
          /*
           * If negative lookup caching is enabled, I might as well
           * add an entry for this node. Not necessary for correctness,
           * but if negative caching is enabled, then the system
           * must care about lookup caching hit rate, so...
           */
          if (newnfs_neglookup_enable != 0 &&
              (cnp->cn_flags & MAKEENTRY))
                  cache_enter(tdvp, vp, cnp);
          if (error && NFS_ISV4(vp))
                  error = nfscl_maperr(cnp->cn_thread, error, (uid_t)0,
                      (gid_t)0);
          return (error);
  }
  
  /*
   * nfs symbolic link create call
   */
  static int
  nfs_symlink(struct vop_symlink_args *ap)
  {
          struct vnode *dvp = ap->a_dvp;
          struct vattr *vap = ap->a_vap;
          struct componentname *cnp = ap->a_cnp;
          struct nfsvattr nfsva, dnfsva;
          struct nfsfh *nfhp;
          struct nfsnode *np = NULL, *dnp;
          struct vnode *newvp = NULL;
          int error = 0, attrflag, dattrflag, ret;
  
          vap->va_type = VLNK;
          error = nfsrpc_symlink(dvp, cnp->cn_nameptr, cnp->cn_namelen,
              ap->a_target, vap, cnp->cn_cred, cnp->cn_thread, &dnfsva,
              &nfsva, &nfhp, &attrflag, &dattrflag, NULL);
          if (nfhp) {
                  ret = nfscl_nget(dvp->v_mount, dvp, nfhp, cnp, cnp->cn_thread,
                      &np, NULL);
                  if (!ret)
                          newvp = NFSTOV(np);
                  else if (!error)
                          error = ret;
          }
          if (newvp != NULL) {
                  if (attrflag)
                          (void) nfscl_loadattrcache(&newvp, &nfsva, NULL, NULL,
                              0, 1);
          } else if (!error) {
                  /*
                   * If we do not have an error and we could not extract the
                   * newvp from the response due to the request being NFSv2, we
                   * have to do a lookup in order to obtain a newvp to return.
                   */
                  error = nfs_lookitup(dvp, cnp->cn_nameptr, cnp->cn_namelen,
                      cnp->cn_cred, cnp->cn_thread, &np);
                  if (!error)
                          newvp = NFSTOV(np);
          }
          if (error) {
                  if (newvp)
                          vput(newvp);
                  if (NFS_ISV4(dvp))
                          error = nfscl_maperr(cnp->cn_thread, error,
                              vap->va_uid, vap->va_gid);
          } else {
                  /*
                   * If negative lookup caching is enabled, I might as well
                   * add an entry for this node. Not necessary for correctness,
                   * but if negative caching is enabled, then the system
                   * must care about lookup caching hit rate, so...
                   */
                  if (newnfs_neglookup_enable != 0 &&
                      (cnp->cn_flags & MAKEENTRY))
                          cache_enter(dvp, newvp, cnp);
                  *ap->a_vpp = newvp;
          }
  
          dnp = VTONFS(dvp);
          mtx_lock(&dnp->n_mtx);
          dnp->n_flag |= NMODIFIED;
          mtx_unlock(&dnp->n_mtx);
          if (dattrflag)
                  (void) nfscl_loadattrcache(&dvp, &dnfsva, NULL, NULL, 0, 1);
          else
                  dnp->n_attrstamp = 0;
          return (error);
  }
  
  /*
   * nfs make dir call
   */
  static int
  nfs_mkdir(struct vop_mkdir_args *ap)
  {
          struct vnode *dvp = ap->a_dvp;
          struct vattr *vap = ap->a_vap;
          struct componentname *cnp = ap->a_cnp;
          struct nfsnode *np = NULL, *dnp;
          struct vnode *newvp = NULL;
          struct vattr vattr;
          struct nfsfh *nfhp;
          struct nfsvattr nfsva, dnfsva;
          int error = 0, attrflag, dattrflag, ret;
  
          if ((error = VOP_GETATTR(dvp, &vattr, cnp->cn_cred)))
                  return (error);
          vap->va_type = VDIR;
          error = nfsrpc_mkdir(dvp, cnp->cn_nameptr, cnp->cn_namelen,
              vap, cnp->cn_cred, cnp->cn_thread, &dnfsva, &nfsva, &nfhp,
              &attrflag, &dattrflag, NULL);
          dnp = VTONFS(dvp);
          mtx_lock(&dnp->n_mtx);
          dnp->n_flag |= NMODIFIED;
          mtx_unlock(&dnp->n_mtx);
          if (dattrflag)
                  (void) nfscl_loadattrcache(&dvp, &dnfsva, NULL, NULL, 0, 1);
          else
                  dnp->n_attrstamp = 0;
          if (nfhp) {
                  ret = nfscl_nget(dvp->v_mount, dvp, nfhp, cnp, cnp->cn_thread,
                      &np, NULL);
                  if (!ret) {
                          newvp = NFSTOV(np);
                          if (attrflag)
                             (void) nfscl_loadattrcache(&newvp, &nfsva, NULL,
                                  NULL, 0, 1);
                  } else if (!error)
                          error = ret;
          }
          if (!error && newvp == NULL) {
                  error = nfs_lookitup(dvp, cnp->cn_nameptr, cnp->cn_namelen,
                      cnp->cn_cred, cnp->cn_thread, &np);
                  if (!error) {
                          newvp = NFSTOV(np);
                          if (newvp->v_type != VDIR)
                                  error = EEXIST;
                  }
          }
          if (error) {
                  if (newvp)
                          vput(newvp);
                  if (NFS_ISV4(dvp))
                          error = nfscl_maperr(cnp->cn_thread, error,
                              vap->va_uid, vap->va_gid);
          } else {
                  /*
                   * If negative lookup caching is enabled, I might as well
                   * add an entry for this node. Not necessary for correctness,
                   * but if negative caching is enabled, then the system
                   * must care about lookup caching hit rate, so...
                   */
                  if (newnfs_neglookup_enable != 0 &&
                      (cnp->cn_flags & MAKEENTRY))
                          cache_enter(dvp, newvp, cnp);
                  *ap->a_vpp = newvp;
          }
          return (error);
  }
  
  /*
   * nfs remove directory call
   */
  static int
  nfs_rmdir(struct vop_rmdir_args *ap)
  {
          struct vnode *vp = ap->a_vp;
          struct vnode *dvp = ap->a_dvp;
          struct componentname *cnp = ap->a_cnp;
          struct nfsnode *dnp;
          struct nfsvattr dnfsva;
          int error, dattrflag;
  
          if (dvp == vp)
                  return (EINVAL);
          error = nfsrpc_rmdir(dvp, cnp->cn_nameptr, cnp->cn_namelen,
              cnp->cn_cred, cnp->cn_thread, &dnfsva, &dattrflag, NULL);
          dnp = VTONFS(dvp);
          mtx_lock(&dnp->n_mtx);
          dnp->n_flag |= NMODIFIED;
          mtx_unlock(&dnp->n_mtx);
          if (dattrflag)
                  (void) nfscl_loadattrcache(&dvp, &dnfsva, NULL, NULL, 0, 1);
          else
                  dnp->n_attrstamp = 0;
  
          cache_purge(dvp);
          cache_purge(vp);
          if (error && NFS_ISV4(dvp))
                  error = nfscl_maperr(cnp->cn_thread, error, (uid_t)0,
                      (gid_t)0);
          /*
           * Kludge: Map ENOENT => 0 assuming that you have a reply to a retry.
           */
          if (error == ENOENT)
                  error = 0;
          return (error);
  }
  
  /*
   * nfs readdir call
   */
  static int
  nfs_readdir(struct vop_readdir_args *ap)
  {
          struct vnode *vp = ap->a_vp;
          struct nfsnode *np = VTONFS(vp);
          struct uio *uio = ap->a_uio;
          int tresid, error = 0;
          struct vattr vattr;
          
          if (vp->v_type != VDIR) 
                  return(EPERM);
  
          /*
           * First, check for hit on the EOF offset cache
           */
          if (np->n_direofoffset > 0 && uio->uio_offset >= np->n_direofoffset &&
              (np->n_flag & NMODIFIED) == 0) {
                  if (VOP_GETATTR(vp, &vattr, ap->a_cred) == 0) {
                          mtx_lock(&np->n_mtx);
                          if ((NFS_ISV4(vp) && np->n_change == vattr.va_filerev) ||
                              !NFS_TIMESPEC_COMPARE(&np->n_mtime, &vattr.va_mtime)) {
                                  mtx_unlock(&np->n_mtx);
                                  NFSINCRGLOBAL(newnfsstats.direofcache_hits);
                                  return (0);
                          } else
                                  mtx_unlock(&np->n_mtx);
                  }
          }
  
          /*
           * Call ncl_bioread() to do the real work.
           */
          tresid = uio->uio_resid;
          error = ncl_bioread(vp, uio, 0, ap->a_cred);
  
          if (!error && uio->uio_resid == tresid)
                  NFSINCRGLOBAL(newnfsstats.direofcache_misses);
          return (error);
  }
  
  /*
   * Readdir rpc call.
   * Called from below the buffer cache by ncl_doio().
   */
  int
  ncl_readdirrpc(struct vnode *vp, struct uio *uiop, struct ucred *cred,
      struct thread *td)
  {
          struct nfsvattr nfsva;
          nfsuint64 *cookiep, cookie;
          struct nfsnode *dnp = VTONFS(vp);
          struct nfsmount *nmp = VFSTONFS(vp->v_mount);
          int error = 0, eof, attrflag;
  
  #ifndef DIAGNOSTIC
          if (uiop->uio_iovcnt != 1 || (uiop->uio_offset & (DIRBLKSIZ - 1)) ||
                  (uiop->uio_resid & (DIRBLKSIZ - 1)))
                  panic("nfs readdirrpc bad uio");
  #endif
  
          /*
           * If there is no cookie, assume directory was stale.
           */
          ncl_dircookie_lock(dnp);
          cookiep = ncl_getcookie(dnp, uiop->uio_offset, 0);
          if (cookiep) {
                  cookie = *cookiep;
                  ncl_dircookie_unlock(dnp);
          } else {
                  ncl_dircookie_unlock(dnp);              
                  return (NFSERR_BAD_COOKIE);
          }
  
          if (NFSHASNFSV3(nmp) && !NFSHASGOTFSINFO(nmp))
                  (void)ncl_fsinfo(nmp, vp, cred, td);
  
          error = nfsrpc_readdir(vp, uiop, &cookie, cred, td, &nfsva,
              &attrflag, &eof, NULL);
          if (attrflag)
                  (void) nfscl_loadattrcache(&vp, &nfsva, NULL, NULL, 0, 1);
  
          if (!error) {
                  /*
                   * We are now either at the end of the directory or have filled
                   * the block.
                   */
                  if (eof)
                          dnp->n_direofoffset = uiop->uio_offset;
                  else {
                          if (uiop->uio_resid > 0)
                                  ncl_printf("EEK! readdirrpc resid > 0\n");
                          ncl_dircookie_lock(dnp);
                          cookiep = ncl_getcookie(dnp, uiop->uio_offset, 1);
                          *cookiep = cookie;
                          ncl_dircookie_unlock(dnp);
                  }
          } else if (NFS_ISV4(vp)) {
                  error = nfscl_maperr(td, error, (uid_t)0, (gid_t)0);
          }
          return (error);
  }
  
  /*
   * NFS V3 readdir plus RPC. Used in place of ncl_readdirrpc().
   */
  int
  ncl_readdirplusrpc(struct vnode *vp, struct uio *uiop, struct ucred *cred,
      struct thread *td)
  {
          struct nfsvattr nfsva;
          nfsuint64 *cookiep, cookie;
          struct nfsnode *dnp = VTONFS(vp);
          struct nfsmount *nmp = VFSTONFS(vp->v_mount);
          int error = 0, attrflag, eof;
  
  #ifndef DIAGNOSTIC
          if (uiop->uio_iovcnt != 1 || (uiop->uio_offset & (DIRBLKSIZ - 1)) ||
                  (uiop->uio_resid & (DIRBLKSIZ - 1)))
                  panic("nfs readdirplusrpc bad uio");
  #endif
  
          /*
           * If there is no cookie, assume directory was stale.
           */
          ncl_dircookie_lock(dnp);
          cookiep = ncl_getcookie(dnp, uiop->uio_offset, 0);
          if (cookiep) {
                  cookie = *cookiep;
                  ncl_dircookie_unlock(dnp);
          } else {
                  ncl_dircookie_unlock(dnp);
                  return (NFSERR_BAD_COOKIE);
          }
  
          if (NFSHASNFSV3(nmp) && !NFSHASGOTFSINFO(nmp))
                  (void)ncl_fsinfo(nmp, vp, cred, td);
          error = nfsrpc_readdirplus(vp, uiop, &cookie, cred, td, &nfsva,
              &attrflag, &eof, NULL);
          if (attrflag)
                  (void) nfscl_loadattrcache(&vp, &nfsva, NULL, NULL, 0, 1);
  
          if (!error) {
                  /*
                   * We are now either at end of the directory or have filled the
                   * the block.
                   */
                  if (eof)
                          dnp->n_direofoffset = uiop->uio_offset;
                  else {
                          if (uiop->uio_resid > 0)
                                  ncl_printf("EEK! readdirplusrpc resid > 0\n");
                          ncl_dircookie_lock(dnp);
                          cookiep = ncl_getcookie(dnp, uiop->uio_offset, 1);
                          *cookiep = cookie;
                          ncl_dircookie_unlock(dnp);
                  }
          } else if (NFS_ISV4(vp)) {
                  error = nfscl_maperr(td, error, (uid_t)0, (gid_t)0);
          }
          return (error);
  }
  
  /*
   * Silly rename. To make the NFS filesystem that is stateless look a little
   * more like the "ufs" a remove of an active vnode is translated to a rename
   * to a funny looking filename that is removed by nfs_inactive on the
   * nfsnode. There is the potential for another process on a different client
   * to create the same funny name between the nfs_lookitup() fails and the
   * nfs_rename() completes, but...
   */
  static int
  nfs_sillyrename(struct vnode *dvp, struct vnode *vp, struct componentname *cnp)
  {
          struct sillyrename *sp;
          struct nfsnode *np;
          int error;
          short pid;
          unsigned int lticks;
  
          cache_purge(dvp);
          np = VTONFS(vp);
  #ifndef DIAGNOSTIC
          if (vp->v_type == VDIR)
                  panic("nfs: sillyrename dir");
  #endif
          MALLOC(sp, struct sillyrename *, sizeof (struct sillyrename),
              M_NEWNFSREQ, M_WAITOK);
          sp->s_cred = crhold(cnp->cn_cred);
          sp->s_dvp = dvp;
          VREF(dvp);
  
          /* 
           * Fudge together a funny name.
           * Changing the format of the funny name to accomodate more 
           * sillynames per directory.
           * The name is now changed to .nfs.<ticks>.<pid>.4, where ticks is 
           * CPU ticks since boot.
           */
          pid = cnp->cn_thread->td_proc->p_pid;
          lticks = (unsigned int)ticks;
          for ( ; ; ) {
                  sp->s_namlen = sprintf(sp->s_name, 
                                         ".nfs.%08x.%04x4.4", lticks, 
                                         pid);
                  if (nfs_lookitup(dvp, sp->s_name, sp->s_namlen, sp->s_cred,
                                   cnp->cn_thread, NULL))
                          break;
                  lticks++;
          }
          error = nfs_renameit(dvp, vp, cnp, sp);
          if (error)
                  goto bad;
          error = nfs_lookitup(dvp, sp->s_name, sp->s_namlen, sp->s_cred,
                  cnp->cn_thread, &np);
          np->n_sillyrename = sp;
          return (0);
  bad:
          vrele(sp->s_dvp);
          crfree(sp->s_cred);
          free((caddr_t)sp, M_NEWNFSREQ);
          return (error);
  }
  
  /*
   * Look up a file name and optionally either update the file handle or
   * allocate an nfsnode, depending on the value of npp.
   * npp == NULL  --> just do the lookup
   * *npp == NULL --> allocate a new nfsnode and make sure attributes are
   *                      handled too
   * *npp != NULL --> update the file handle in the vnode
   */
  static int
  nfs_lookitup(struct vnode *dvp, char *name, int len, struct ucred *cred,
      struct thread *td, struct nfsnode **npp)
  {
          struct vnode *newvp = NULL, *vp;
          struct nfsnode *np, *dnp = VTONFS(dvp);
          struct nfsfh *nfhp, *onfhp;
          struct nfsvattr nfsva, dnfsva;
          struct componentname cn;
          int error = 0, attrflag, dattrflag;
          u_int hash;
  
          error = nfsrpc_lookup(dvp, name, len, cred, td, &dnfsva, &nfsva,
              &nfhp, &attrflag, &dattrflag, NULL);
          if (dattrflag)
                  (void) nfscl_loadattrcache(&dvp, &dnfsva, NULL, NULL, 0, 1);
          if (npp && !error) {
                  if (*npp != NULL) {
                      np = *npp;
                      vp = NFSTOV(np);
                      /*
                       * For NFSv4, check to see if it is the same name and
                       * replace the name, if it is different.
                       */
                      if (np->n_v4 != NULL && nfsva.na_type == VREG &&
                          (np->n_v4->n4_namelen != len ||
                           NFSBCMP(name, NFS4NODENAME(np->n_v4), len) ||
                           dnp->n_fhp->nfh_len != np->n_v4->n4_fhlen ||
                           NFSBCMP(dnp->n_fhp->nfh_fh, np->n_v4->n4_data,
                           dnp->n_fhp->nfh_len))) {
  #ifdef notdef
  { char nnn[100]; int nnnl;
  nnnl = (len < 100) ? len : 99;
  bcopy(name, nnn, nnnl);
  nnn[nnnl] = '\0';
  printf("replace=%s\n",nnn);
  }
  #endif
                              FREE((caddr_t)np->n_v4, M_NFSV4NODE);
                              MALLOC(np->n_v4, struct nfsv4node *,
                                  sizeof (struct nfsv4node) +
                                  dnp->n_fhp->nfh_len + len - 1,
                                  M_NFSV4NODE, M_WAITOK);
                              np->n_v4->n4_fhlen = dnp->n_fhp->nfh_len;
                              np->n_v4->n4_namelen = len;
                              NFSBCOPY(dnp->n_fhp->nfh_fh, np->n_v4->n4_data,
                                  dnp->n_fhp->nfh_len);
                              NFSBCOPY(name, NFS4NODENAME(np->n_v4), len);
                      }
                      hash = fnv_32_buf(nfhp->nfh_fh, nfhp->nfh_len,
                          FNV1_32_INIT);
                      onfhp = np->n_fhp;
                      /*
                       * Rehash node for new file handle.
                       */
                      vfs_hash_rehash(vp, hash);
                      np->n_fhp = nfhp;
                      if (onfhp != NULL)
                          FREE((caddr_t)onfhp, M_NFSFH);
                      newvp = NFSTOV(np);
                  } else if (NFS_CMPFH(dnp, nfhp->nfh_fh, nfhp->nfh_len)) {
                      FREE((caddr_t)nfhp, M_NFSFH);
                      VREF(dvp);
                      newvp = dvp;
                  } else {
                      cn.cn_nameptr = name;
                      cn.cn_namelen = len;
                      error = nfscl_nget(dvp->v_mount, dvp, nfhp, &cn, td,
                          &np, NULL);
                      if (error)
                          return (error);
                      newvp = NFSTOV(np);
                  }
                  if (!attrflag && *npp == NULL) {
                          vrele(newvp);
                          return (ENOENT);
                  }
                  if (attrflag)
                          (void) nfscl_loadattrcache(&newvp, &nfsva, NULL, NULL,
                              0, 1);
          }
          if (npp && *npp == NULL) {
                  if (error) {
                          if (newvp) {
                                  if (newvp == dvp)
                                          vrele(newvp);
                                  else
                                          vput(newvp);
                          }
                  } else
                          *npp = np;
          }
          if (error && NFS_ISV4(dvp))
                  error = nfscl_maperr(td, error, (uid_t)0, (gid_t)0);
          return (error);
  }
  
  /*
   * Nfs Version 3 and 4 commit rpc
   */
  int
  ncl_commit(struct vnode *vp, u_quad_t offset, int cnt, struct ucred *cred,
     struct thread *td)
  {
          struct nfsvattr nfsva;
          struct nfsmount *nmp = VFSTONFS(vp->v_mount);
          int error, attrflag;
          u_char verf[NFSX_VERF];
  
          mtx_lock(&nmp->nm_mtx);
          if ((nmp->nm_state & NFSSTA_HASWRITEVERF) == 0) {
                  mtx_unlock(&nmp->nm_mtx);
                  return (0);
          }
          mtx_unlock(&nmp->nm_mtx);
          error = nfsrpc_commit(vp, offset, cnt, cred, td, verf, &nfsva,
              &attrflag, NULL);
          if (!error) {
                  if (NFSBCMP((caddr_t)nmp->nm_verf, verf, NFSX_VERF)) {
                          NFSBCOPY(verf, (caddr_t)nmp->nm_verf, NFSX_VERF);
                          error = NFSERR_STALEWRITEVERF;
                  }
                  if (!error && attrflag)
                          (void) nfscl_loadattrcache(&vp, &nfsva, NULL, NULL,
                              0, 1);
          } else if (NFS_ISV4(vp)) {
                  error = nfscl_maperr(td, error, (uid_t)0, (gid_t)0);
          }
          return (error);
  }
  
  /*
   * Strategy routine.
   * For async requests when nfsiod(s) are running, queue the request by
   * calling ncl_asyncio(), otherwise just all ncl_doio() to do the
   * request.
   */
  static int
  nfs_strategy(struct vop_strategy_args *ap)
  {
          struct buf *bp = ap->a_bp;
          struct ucred *cr;
  
          KASSERT(!(bp->b_flags & B_DONE),
              ("nfs_strategy: buffer %p unexpectedly marked B_DONE", bp));
          BUF_ASSERT_HELD(bp);
  
          if (bp->b_iocmd == BIO_READ)
                  cr = bp->b_rcred;
          else
                  cr = bp->b_wcred;
  
          /*
           * If the op is asynchronous and an i/o daemon is waiting
           * queue the request, wake it up and wait for completion
           * otherwise just do it ourselves.
           */
          if ((bp->b_flags & B_ASYNC) == 0 ||
              ncl_asyncio(VFSTONFS(ap->a_vp->v_mount), bp, NOCRED, curthread))
                  (void)ncl_doio(ap->a_vp, bp, cr, curthread);
          return (0);
  }
  
  /*
   * fsync vnode op. Just call ncl_flush() with commit == 1.
   */
  /* ARGSUSED */
  static int
  nfs_fsync(struct vop_fsync_args *ap)
  {
          return (ncl_flush(ap->a_vp, ap->a_waitfor, NULL, ap->a_td, 1));
  }
  
  /*
   * Flush all the blocks associated with a vnode.
   *      Walk through the buffer pool and push any dirty pages
   *      associated with the vnode.
   */
  int
  ncl_flush(struct vnode *vp, int waitfor, struct ucred *cred, struct thread *td,
      int commit)
  {
          struct nfsnode *np = VTONFS(vp);
          struct buf *bp;
          int i;
          struct buf *nbp;
          struct nfsmount *nmp = VFSTONFS(vp->v_mount);
          int error = 0, slptimeo = 0, slpflag = 0, retv, bvecpos;
          int passone = 1, trycnt = 0;
          u_quad_t off, endoff, toff;
          struct ucred* wcred = NULL;
          struct buf **bvec = NULL;
          struct bufobj *bo;
  #ifndef NFS_COMMITBVECSIZ
  #define NFS_COMMITBVECSIZ       20
  #endif
          struct buf *bvec_on_stack[NFS_COMMITBVECSIZ];
          int bvecsize = 0, bveccount;
  
          if (nmp->nm_flag & NFSMNT_INT)
                  slpflag = NFS_PCATCH;
          if (!commit)
                  passone = 0;
          bo = &vp->v_bufobj;
          /*
           * A b_flags == (B_DELWRI | B_NEEDCOMMIT) block has been written to the
           * server, but has not been committed to stable storage on the server
           * yet. On the first pass, the byte range is worked out and the commit
           * rpc is done. On the second pass, ncl_writebp() is called to do the
           * job.
           */
  again:
          off = (u_quad_t)-1;
          endoff = 0;
          bvecpos = 0;
          if (NFS_ISV34(vp) && commit) {
                  if (bvec != NULL && bvec != bvec_on_stack)
                          free(bvec, M_TEMP);
                  /*
                   * Count up how many buffers waiting for a commit.
                   */
                  bveccount = 0;
                  BO_LOCK(bo);
                  TAILQ_FOREACH_SAFE(bp, &bo->bo_dirty.bv_hd, b_bobufs, nbp) {
                          if (!BUF_ISLOCKED(bp) &&
                              (bp->b_flags & (B_DELWRI | B_NEEDCOMMIT))
                                  == (B_DELWRI | B_NEEDCOMMIT))
                                  bveccount++;
                  }
                  /*
                   * Allocate space to remember the list of bufs to commit.  It is
                   * important to use M_NOWAIT here to avoid a race with nfs_write.
                   * If we can't get memory (for whatever reason), we will end up
                   * committing the buffers one-by-one in the loop below.
                   */
                  if (bveccount > NFS_COMMITBVECSIZ) {
                          /*
                           * Release the vnode interlock to avoid a lock
                           * order reversal.
                           */
                          BO_UNLOCK(bo);
                          bvec = (struct buf **)
                                  malloc(bveccount * sizeof(struct buf *),
                                         M_TEMP, M_NOWAIT);
                          BO_LOCK(bo);
                          if (bvec == NULL) {
                                  bvec = bvec_on_stack;
                                  bvecsize = NFS_COMMITBVECSIZ;
                          } else
                                  bvecsize = bveccount;
                  } else {
                          bvec = bvec_on_stack;
                          bvecsize = NFS_COMMITBVECSIZ;
                  }
                  TAILQ_FOREACH_SAFE(bp, &bo->bo_dirty.bv_hd, b_bobufs, nbp) {
                          if (bvecpos >= bvecsize)
                                  break;
                          if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL)) {
                                  nbp = TAILQ_NEXT(bp, b_bobufs);
                                  continue;
                          }
                          if ((bp->b_flags & (B_DELWRI | B_NEEDCOMMIT)) !=
                              (B_DELWRI | B_NEEDCOMMIT)) {
                                  BUF_UNLOCK(bp);
                                  nbp = TAILQ_NEXT(bp, b_bobufs);
                                  continue;
                          }
                          BO_UNLOCK(bo);
                          bremfree(bp);
                          /*
                           * Work out if all buffers are using the same cred
                           * so we can deal with them all with one commit.
                           *
                           * NOTE: we are not clearing B_DONE here, so we have
                           * to do it later on in this routine if we intend to
                           * initiate I/O on the bp.
                           *
                           * Note: to avoid loopback deadlocks, we do not
                           * assign b_runningbufspace.
                           */
                          if (wcred == NULL)
                                  wcred = bp->b_wcred;
                          else if (wcred != bp->b_wcred)
                                  wcred = NOCRED;
                          vfs_busy_pages(bp, 1);
  
                          BO_LOCK(bo);
                          /*
                           * bp is protected by being locked, but nbp is not
                           * and vfs_busy_pages() may sleep.  We have to
                           * recalculate nbp.
                           */
                          nbp = TAILQ_NEXT(bp, b_bobufs);
  
                          /*
                           * A list of these buffers is kept so that the
                           * second loop knows which buffers have actually
                           * been committed. This is necessary, since there
                           * may be a race between the commit rpc and new
                           * uncommitted writes on the file.
                           */
                          bvec[bvecpos++] = bp;
                          toff = ((u_quad_t)bp->b_blkno) * DEV_BSIZE +
                                  bp->b_dirtyoff;
                          if (toff < off)
                                  off = toff;
                          toff += (u_quad_t)(bp->b_dirtyend - bp->b_dirtyoff);
                          if (toff > endoff)
                                  endoff = toff;
                  }
                  BO_UNLOCK(bo);
          }
          if (bvecpos > 0) {
                  /*
                   * Commit data on the server, as required.
                   * If all bufs are using the same wcred, then use that with
                   * one call for all of them, otherwise commit each one
                   * separately.
                   */
                  if (wcred != NOCRED)
                          retv = ncl_commit(vp, off, (int)(endoff - off),
                                            wcred, td);
                  else {
                          retv = 0;
                          for (i = 0; i < bvecpos; i++) {
                                  off_t off, size;
                                  bp = bvec[i];
                                  off = ((u_quad_t)bp->b_blkno) * DEV_BSIZE +
                                          bp->b_dirtyoff;
                                  size = (u_quad_t)(bp->b_dirtyend
                                                    - bp->b_dirtyoff);
                                  retv = ncl_commit(vp, off, (int)size,
                                                    bp->b_wcred, td);
                                  if (retv) break;
                          }
                  }
  
                  if (retv == NFSERR_STALEWRITEVERF)
                          ncl_clearcommit(vp->v_mount);
  
                  /*
                   * Now, either mark the blocks I/O done or mark the
                   * blocks dirty, depending on whether the commit
                   * succeeded.
                   */
                  for (i = 0; i < bvecpos; i++) {
                          bp = bvec[i];
                          bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
                          if (retv) {
                                  /*
                                   * Error, leave B_DELWRI intact
                                   */
                                  vfs_unbusy_pages(bp);
                                  brelse(bp);
                          } else {
                                  /*
                                   * Success, remove B_DELWRI ( bundirty() ).
                                   *
                                   * b_dirtyoff/b_dirtyend seem to be NFS
                                   * specific.  We should probably move that
                                   * into bundirty(). XXX
                                   */
                                  bufobj_wref(bo);
                                  bp->b_flags |= B_ASYNC;
                                  bundirty(bp);
                                  bp->b_flags &= ~B_DONE;
                                  bp->b_ioflags &= ~BIO_ERROR;
                                  bp->b_dirtyoff = bp->b_dirtyend = 0;
                                  bufdone(bp);
                          }
                  }
          }
  
          /*
           * Start/do any write(s) that are required.
           */
  loop:
          BO_LOCK(bo);
          TAILQ_FOREACH_SAFE(bp, &bo->bo_dirty.bv_hd, b_bobufs, nbp) {
                  if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL)) {
                          if (waitfor != MNT_WAIT || passone)
                                  continue;
  
                          error = BUF_TIMELOCK(bp,
                              LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK,
                              BO_MTX(bo), "nfsfsync", slpflag, slptimeo);
                          if (error == 0) {
                                  BUF_UNLOCK(bp);
                                  goto loop;
                          }
                          if (error == ENOLCK) {
                                  error = 0;
                                  goto loop;
                          }
                          if (newnfs_sigintr(nmp, td)) {
                                  error = EINTR;
                                  goto done;
                          }
                          if (slpflag & PCATCH) {
                                  slpflag = 0;
                                  slptimeo = 2 * hz;
                          }
                          goto loop;
                  }
                  if ((bp->b_flags & B_DELWRI) == 0)
                          panic("nfs_fsync: not dirty");
                  if ((passone || !commit) && (bp->b_flags & B_NEEDCOMMIT)) {
                          BUF_UNLOCK(bp);
                          continue;
                  }
                  BO_UNLOCK(bo);
                  bremfree(bp);
                  if (passone || !commit)
                      bp->b_flags |= B_ASYNC;
                  else
                      bp->b_flags |= B_ASYNC;
                  bwrite(bp);
                  if (newnfs_sigintr(nmp, td)) {
                          error = EINTR;
                          goto done;
                  }
                  goto loop;
          }
          if (passone) {
                  passone = 0;
                  BO_UNLOCK(bo);
                  goto again;
          }
          if (waitfor == MNT_WAIT) {
                  while (bo->bo_numoutput) {
                          error = bufobj_wwait(bo, slpflag, slptimeo);
                          if (error) {
                              BO_UNLOCK(bo);
                              error = newnfs_sigintr(nmp, td);
                              if (error)
                                  goto done;
                              if (slpflag & PCATCH) {
                                  slpflag = 0;
                                  slptimeo = 2 * hz;
                              }
                              BO_LOCK(bo);
                          }
                  }
                  if (bo->bo_dirty.bv_cnt != 0 && commit) {
                          BO_UNLOCK(bo);
                          goto loop;
                  }
                  /*
                   * Wait for all the async IO requests to drain
                   */
                  BO_UNLOCK(bo);
                  mtx_lock(&np->n_mtx);
                  while (np->n_directio_asyncwr > 0) {
                          np->n_flag |= NFSYNCWAIT;
                          error = ncl_msleep(td, (caddr_t)&np->n_directio_asyncwr,
                                             &np->n_mtx, slpflag | (PRIBIO + 1), 
                                             "nfsfsync", 0);
                          if (error) {
                                  if (newnfs_sigintr(nmp, td)) {
                                          mtx_unlock(&np->n_mtx);
                                          error = EINTR;  
                                          goto done;
                                  }
                          }
                  }
                  mtx_unlock(&np->n_mtx);
          } else
                  BO_UNLOCK(bo);
          mtx_lock(&np->n_mtx);
          if (np->n_flag & NWRITEERR) {
                  error = np->n_error;
                  np->n_flag &= ~NWRITEERR;
          }
          if (commit && bo->bo_dirty.bv_cnt == 0 &&
              bo->bo_numoutput == 0 && np->n_directio_asyncwr == 0)
                  np->n_flag &= ~NMODIFIED;
          mtx_unlock(&np->n_mtx);
  done:
          if (bvec != NULL && bvec != bvec_on_stack)
                  free(bvec, M_TEMP);
          if (error == 0 && commit != 0 && waitfor == MNT_WAIT &&
              (bo->bo_dirty.bv_cnt != 0 || bo->bo_numoutput != 0 ||
               np->n_directio_asyncwr != 0) && trycnt++ < 5) {
                  /* try, try again... */
                  passone = 1;
                  wcred = NULL;
                  bvec = NULL;
                  bvecsize = 0;
  printf("try%d\n", trycnt);
                  goto again;
          }
          return (error);
  }
  
  /*
   * NFS advisory byte-level locks.
   */
  static int
  nfs_advlock(struct vop_advlock_args *ap)
  {
          struct vnode *vp = ap->a_vp;
          struct ucred *cred;
          struct nfsnode *np = VTONFS(ap->a_vp);
          struct proc *p = (struct proc *)ap->a_id;
          struct thread *td = curthread;  /* XXX */
          struct vattr va;
          int ret, error = EOPNOTSUPP;
          u_quad_t size;
          
          if (NFS_ISV4(vp) && (ap->a_flags & F_POSIX)) {
                  cred = p->p_ucred;
                  vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                  if (vp->v_iflag & VI_DOOMED) {
                          VOP_UNLOCK(vp, 0);
                          return (EBADF);
                  }
  
                  /*
                   * If this is unlocking a write locked region, flush and
                   * commit them before unlocking. This is required by
                   * RFC3530 Sec. 9.3.2.
                   */
                  if (ap->a_op == F_UNLCK &&
                      nfscl_checkwritelocked(vp, ap->a_fl, cred, td))
                          (void) ncl_flush(vp, MNT_WAIT, cred, td, 1);
  
                  /*
                   * Loop around doing the lock op, while a blocking lock
                   * must wait for the lock op to succeed.
                   */
                  do {
                          ret = nfsrpc_advlock(vp, np->n_size, ap->a_op,
                              ap->a_fl, 0, cred, td);
                          if (ret == NFSERR_DENIED && (ap->a_flags & F_WAIT) &&
                              ap->a_op == F_SETLK) {
                                  VOP_UNLOCK(vp, 0);
                                  error = nfs_catnap(PZERO | PCATCH, "ncladvl");
                                  if (error)
                                          return (EINTR);
                                  vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                                  if (vp->v_iflag & VI_DOOMED) {
                                          VOP_UNLOCK(vp, 0);
                                          return (EBADF);
                                  }
                          }
                  } while (ret == NFSERR_DENIED && (ap->a_flags & F_WAIT) &&
                       ap->a_op == F_SETLK);
                  if (ret == NFSERR_DENIED) {
                          VOP_UNLOCK(vp, 0);
                          return (EAGAIN);
                  } else if (ret == EINVAL || ret == EBADF || ret == EINTR) {
                          VOP_UNLOCK(vp, 0);
                          return (ret);
                  } else if (ret != 0) {
                          VOP_UNLOCK(vp, 0);
                          return (EACCES);
                  }
  
                  /*
                   * Now, if we just got a lock, invalidate data in the buffer
                   * cache, as required, so that the coherency conforms with
                   * RFC3530 Sec. 9.3.2.
                   */
                  if (ap->a_op == F_SETLK) {
                          if ((np->n_flag & NMODIFIED) == 0) {
                                  np->n_attrstamp = 0;
                                  ret = VOP_GETATTR(vp, &va, cred);
                          }
                          if ((np->n_flag & NMODIFIED) || ret ||
                              np->n_change != va.va_filerev) {
                                  (void) ncl_vinvalbuf(vp, V_SAVE, td, 1);
                                  np->n_attrstamp = 0;
                                  ret = VOP_GETATTR(vp, &va, cred);
                                  if (!ret) {
                                          np->n_mtime = va.va_mtime;
                                          np->n_change = va.va_filerev;
                                  }
                          }
                  }
                  VOP_UNLOCK(vp, 0);
                  return (0);
          } else if (!NFS_ISV4(vp)) {
                  error = vn_lock(vp, LK_SHARED);
                  if (error)
                          return (error);
                  if ((VFSTONFS(vp->v_mount)->nm_flag & NFSMNT_NOLOCKD) != 0) {
                          size = VTONFS(vp)->n_size;
                          VOP_UNLOCK(vp, 0);
                          error = lf_advlock(ap, &(vp->v_lockf), size);
                  } else {
                          if (ncl_advlock_p)
                                  error = ncl_advlock_p(ap);
                          else
                                  error = ENOLCK;
                  }
          }
          return (error);
  }
  
  /*
   * NFS advisory byte-level locks.
   */
  static int
  nfs_advlockasync(struct vop_advlockasync_args *ap)
  {
          struct vnode *vp = ap->a_vp;
          u_quad_t size;
          int error;
          
          if (NFS_ISV4(vp))
                  return (EOPNOTSUPP);
          error = vn_lock(vp, LK_SHARED);
          if (error)
                  return (error);
          if ((VFSTONFS(vp->v_mount)->nm_flag & NFSMNT_NOLOCKD) != 0) {
                  size = VTONFS(vp)->n_size;
                  VOP_UNLOCK(vp, 0);
                  error = lf_advlockasync(ap, &(vp->v_lockf), size);
          } else {
                  VOP_UNLOCK(vp, 0);
                  error = EOPNOTSUPP;
          }
          return (error);
  }
  
  /*
   * Print out the contents of an nfsnode.
   */
  static int
  nfs_print(struct vop_print_args *ap)
  {
          struct vnode *vp = ap->a_vp;
          struct nfsnode *np = VTONFS(vp);
  
          ncl_printf("\tfileid %ld fsid 0x%x",
             np->n_vattr.na_fileid, np->n_vattr.na_fsid);
          if (vp->v_type == VFIFO)
                  fifo_printinfo(vp);
          printf("\n");
          return (0);
  }
  
  /*
   * This is the "real" nfs::bwrite(struct buf*).
   * We set B_CACHE if this is a VMIO buffer.
   */
  int
  ncl_writebp(struct buf *bp, int force __unused, struct thread *td)
  {
          int s;
          int oldflags = bp->b_flags;
  #if 0
          int retv = 1;
          off_t off;
  #endif
  
          BUF_ASSERT_HELD(bp);
  
          if (bp->b_flags & B_INVAL) {
                  brelse(bp);
                  return(0);
          }
  
          bp->b_flags |= B_CACHE;
  
          /*
           * Undirty the bp.  We will redirty it later if the I/O fails.
           */
  
          s = splbio();
          bundirty(bp);
          bp->b_flags &= ~B_DONE;
          bp->b_ioflags &= ~BIO_ERROR;
          bp->b_iocmd = BIO_WRITE;
  
          bufobj_wref(bp->b_bufobj);
          curthread->td_ru.ru_oublock++;
          splx(s);
  
          /*
           * Note: to avoid loopback deadlocks, we do not
           * assign b_runningbufspace.
           */
          vfs_busy_pages(bp, 1);
  
          BUF_KERNPROC(bp);
          bp->b_iooffset = dbtob(bp->b_blkno);
          bstrategy(bp);
  
          if( (oldflags & B_ASYNC) == 0) {
                  int rtval = bufwait(bp);
  
                  if (oldflags & B_DELWRI) {
                          s = splbio();
                          reassignbuf(bp);
                          splx(s);
                  }
                  brelse(bp);
                  return (rtval);
          }
  
          return (0);
  }
  
  /*
   * nfs special file access vnode op.
   * Essentially just get vattr and then imitate iaccess() since the device is
   * local to the client.
   */
  static int
  nfsspec_access(struct vop_access_args *ap)
  {
          struct vattr *vap;
          struct ucred *cred = ap->a_cred;
          struct vnode *vp = ap->a_vp;
          accmode_t accmode = ap->a_accmode;
          struct vattr vattr;
          int error;
  
          /*
           * Disallow write attempts on filesystems mounted read-only;
           * unless the file is a socket, fifo, or a block or character
           * device resident on the filesystem.
           */
          if ((accmode & VWRITE) && (vp->v_mount->mnt_flag & MNT_RDONLY)) {
                  switch (vp->v_type) {
                  case VREG:
                  case VDIR:
                  case VLNK:
                          return (EROFS);
                  default:
                          break;
                  }
          }
          vap = &vattr;
          error = VOP_GETATTR(vp, vap, cred);
          if (error)
                  goto out;
          error  = vaccess(vp->v_type, vap->va_mode, vap->va_uid, vap->va_gid,
              accmode, cred, NULL);
  out:
          return error;
  }
  
  /*
   * Read wrapper for fifos.
   */
  static int
  nfsfifo_read(struct vop_read_args *ap)
  {
          struct nfsnode *np = VTONFS(ap->a_vp);
          int error;
  
          /*
           * Set access flag.
           */
          mtx_lock(&np->n_mtx);
          np->n_flag |= NACC;
          getnanotime(&np->n_atim);
          mtx_unlock(&np->n_mtx);
          error = fifo_specops.vop_read(ap);
          return error;   
  }
  
  /*
   * Write wrapper for fifos.
   */
  static int
  nfsfifo_write(struct vop_write_args *ap)
  {
          struct nfsnode *np = VTONFS(ap->a_vp);
  
          /*
           * Set update flag.
           */
          mtx_lock(&np->n_mtx);
          np->n_flag |= NUPD;
          getnanotime(&np->n_mtim);
          mtx_unlock(&np->n_mtx);
          return(fifo_specops.vop_write(ap));
  }
  
  /*
   * Close wrapper for fifos.
   *
   * Update the times on the nfsnode then do fifo close.
   */
  static int
  nfsfifo_close(struct vop_close_args *ap)
  {
          struct vnode *vp = ap->a_vp;
          struct nfsnode *np = VTONFS(vp);
          struct vattr vattr;
          struct timespec ts;
  
          mtx_lock(&np->n_mtx);
          if (np->n_flag & (NACC | NUPD)) {
                  getnanotime(&ts);
                  if (np->n_flag & NACC)
                          np->n_atim = ts;
                  if (np->n_flag & NUPD)
                          np->n_mtim = ts;
                  np->n_flag |= NCHG;
                  if (vrefcnt(vp) == 1 &&
                      (vp->v_mount->mnt_flag & MNT_RDONLY) == 0) {
                          VATTR_NULL(&vattr);
                          if (np->n_flag & NACC)
                                  vattr.va_atime = np->n_atim;
                          if (np->n_flag & NUPD)
                                  vattr.va_mtime = np->n_mtim;
                          mtx_unlock(&np->n_mtx);
                          (void)VOP_SETATTR(vp, &vattr, ap->a_cred);
                          goto out;
                  }
          }
          mtx_unlock(&np->n_mtx);
  out:
          return (fifo_specops.vop_close(ap));
  }
  
  /*
   * Just call ncl_writebp() with the force argument set to 1.
   *
   * NOTE: B_DONE may or may not be set in a_bp on call.
   */
  static int
  nfs_bwrite(struct buf *bp)
  {
  
          return (ncl_writebp(bp, 1, curthread));
  }
  
  struct buf_ops buf_ops_newnfs = {
          .bop_name       =       "buf_ops_nfs",
          .bop_write      =       nfs_bwrite,
          .bop_strategy   =       bufstrategy,
          .bop_sync       =       bufsync,
          .bop_bdflush    =       bufbdflush,
  };
  
  /*
   * Cloned from vop_stdlock(), and then the ugly hack added.
   */
  static int
  nfs_lock1(struct vop_lock1_args *ap)
  {
          struct vnode *vp = ap->a_vp;
          int error = 0;
  
          /*
           * Since vfs_hash_get() calls vget() and it will no longer work
           * for FreeBSD8 with flags == 0, I can only think of this horrible
           * hack to work around it. I call vfs_hash_get() with LK_EXCLOTHER
           * and then handle it here. All I want for this case is a v_usecount
           * on the vnode to use for recovery, while another thread might
           * hold a lock on the vnode. I have the other threads blocked, so
           * there isn't any race problem.
           */
          if ((ap->a_flags & LK_TYPE_MASK) == LK_EXCLOTHER) {
                  if ((ap->a_flags & LK_INTERLOCK) == 0)
                          panic("ncllock1");
                  if ((vp->v_iflag & VI_DOOMED))
                          error = ENOENT;
                  VI_UNLOCK(vp);
                  return (error);
          }
          return (_lockmgr_args(vp->v_vnlock, ap->a_flags, VI_MTX(vp),
              LK_WMESG_DEFAULT, LK_PRIO_DEFAULT, LK_TIMO_DEFAULT, ap->a_file,
              ap->a_line));
  }
  
  #ifdef NFS4_ACL_EXTATTR_NAME
  static int
  nfs_getacl(struct vop_getacl_args *ap)
  {
          int error;
  
          if (ap->a_type != ACL_TYPE_NFS4)
                  return (EOPNOTSUPP);
          error = nfsrpc_getacl(ap->a_vp, ap->a_cred, ap->a_td, ap->a_aclp,
              NULL);
          if (error > NFSERR_STALE) {
                  (void) nfscl_maperr(ap->a_td, error, (uid_t)0, (gid_t)0);
                  error = EPERM;
          }
          return (error);
  }
  
  static int
  nfs_setacl(struct vop_setacl_args *ap)
  {
          int error;
  
          if (ap->a_type != ACL_TYPE_NFS4)
                  return (EOPNOTSUPP);
          error = nfsrpc_setacl(ap->a_vp, ap->a_cred, ap->a_td, ap->a_aclp,
              NULL);
          if (error > NFSERR_STALE) {
                  (void) nfscl_maperr(ap->a_td, error, (uid_t)0, (gid_t)0);
                  error = EPERM;
          }
          return (error);
  }
  
  #endif  /* NFS4_ACL_EXTATTR_NAME */