FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_default.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 John Heidemann of the UCLA Ficus project.
      *
      * Source: * @(#)i405_init.c 2.10 92/04/27 UCLA Ficus project
      *
     * 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.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/5.3/sys/kern/vfs_default.c 136588 2004-10-16 08:43:07Z cvs2svn $");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/bio.h>
    #include <sys/buf.h>
    #include <sys/conf.h>
    #include <sys/kernel.h>
    #include <sys/limits.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/mount.h>
    #include <sys/mutex.h>
    #include <sys/unistd.h>
    #include <sys/vnode.h>
    #include <sys/poll.h>
    
    #include <vm/vm.h>
    #include <vm/vm_object.h>
    #include <vm/vm_extern.h>
    #include <vm/pmap.h>
    #include <vm/vm_map.h>
    #include <vm/vm_page.h>
    #include <vm/vm_pager.h>
    #include <vm/vnode_pager.h>
    
    static int      vop_nolookup(struct vop_lookup_args *);
    static int      vop_nostrategy(struct vop_strategy_args *);
    
    /*
     * This vnode table stores what we want to do if the filesystem doesn't
     * implement a particular VOP.
     *
     * If there is no specific entry here, we will return EOPNOTSUPP.
     *
     */
    
    vop_t **default_vnodeop_p;
    static struct vnodeopv_entry_desc default_vnodeop_entries[] = {
            { &vop_default_desc,            (vop_t *) vop_eopnotsupp },
            { &vop_advlock_desc,            (vop_t *) vop_einval },
            { &vop_bmap_desc,               (vop_t *) vop_stdbmap },
            { &vop_close_desc,              (vop_t *) vop_null },
            { &vop_createvobject_desc,      (vop_t *) vop_stdcreatevobject },
            { &vop_destroyvobject_desc,     (vop_t *) vop_stddestroyvobject },
            { &vop_fsync_desc,              (vop_t *) vop_null },
            { &vop_getpages_desc,           (vop_t *) vop_stdgetpages },
            { &vop_getvobject_desc,         (vop_t *) vop_stdgetvobject },
            { &vop_inactive_desc,           (vop_t *) vop_stdinactive },
            { &vop_ioctl_desc,              (vop_t *) vop_enotty },
            { &vop_islocked_desc,           (vop_t *) vop_stdislocked },
            { &vop_lease_desc,              (vop_t *) vop_null },
            { &vop_lock_desc,               (vop_t *) vop_stdlock },
            { &vop_lookup_desc,             (vop_t *) vop_nolookup },
            { &vop_open_desc,               (vop_t *) vop_null },
            { &vop_pathconf_desc,           (vop_t *) vop_einval },
            { &vop_poll_desc,               (vop_t *) vop_nopoll },
            { &vop_putpages_desc,           (vop_t *) vop_stdputpages },
            { &vop_readlink_desc,           (vop_t *) vop_einval },
            { &vop_revoke_desc,             (vop_t *) vop_revoke },
            { &vop_specstrategy_desc,       (vop_t *) vop_panic },
            { &vop_strategy_desc,           (vop_t *) vop_nostrategy },
            { &vop_unlock_desc,             (vop_t *) vop_stdunlock },
            { NULL, NULL }
   };
   
   static struct vnodeopv_desc default_vnodeop_opv_desc =
           { &default_vnodeop_p, default_vnodeop_entries };
   
   VNODEOP_SET(default_vnodeop_opv_desc);
   
   /*
    * Series of placeholder functions for various error returns for
    * VOPs.
    */
   
   int
   vop_eopnotsupp(struct vop_generic_args *ap)
   {
           /*
           printf("vop_notsupp[%s]\n", ap->a_desc->vdesc_name);
           */
   
           return (EOPNOTSUPP);
   }
   
   int
   vop_ebadf(struct vop_generic_args *ap)
   {
   
           return (EBADF);
   }
   
   int
   vop_enotty(struct vop_generic_args *ap)
   {
   
           return (ENOTTY);
   }
   
   int
   vop_einval(struct vop_generic_args *ap)
   {
   
           return (EINVAL);
   }
   
   int
   vop_null(struct vop_generic_args *ap)
   {
   
           return (0);
   }
   
   /*
    * Used to make a defined VOP fall back to the default VOP.
    */
   int
   vop_defaultop(struct vop_generic_args *ap)
   {
   
           return (VOCALL(default_vnodeop_p, ap->a_desc->vdesc_offset, ap));
   }
   
   /*
    * Helper function to panic on some bad VOPs in some filesystems.
    */
   int
   vop_panic(struct vop_generic_args *ap)
   {
   
           panic("filesystem goof: vop_panic[%s]", ap->a_desc->vdesc_name);
   }
   
   /*
    * vop_std<something> and vop_no<something> are default functions for use by
    * filesystems that need the "default reasonable" implementation for a
    * particular operation.
    *
    * The documentation for the operations they implement exists (if it exists)
    * in the VOP_<SOMETHING>(9) manpage (all uppercase).
    */
   
   /*
    * Default vop for filesystems that do not support name lookup
    */
   static int
   vop_nolookup(ap)
           struct vop_lookup_args /* {
                   struct vnode *a_dvp;
                   struct vnode **a_vpp;
                   struct componentname *a_cnp;
           } */ *ap;
   {
   
           *ap->a_vpp = NULL;
           return (ENOTDIR);
   }
   
   /*
    *      vop_nostrategy:
    *
    *      Strategy routine for VFS devices that have none.
    *
    *      BIO_ERROR and B_INVAL must be cleared prior to calling any strategy
    *      routine.  Typically this is done for a BIO_READ strategy call.
    *      Typically B_INVAL is assumed to already be clear prior to a write
    *      and should not be cleared manually unless you just made the buffer
    *      invalid.  BIO_ERROR should be cleared either way.
    */
   
   static int
   vop_nostrategy (struct vop_strategy_args *ap)
   {
           KASSERT(ap->a_vp == ap->a_bp->b_vp, ("%s(%p != %p)",
               __func__, ap->a_vp, ap->a_bp->b_vp));
           printf("No strategy for buffer at %p\n", ap->a_bp);
           vprint("vnode", ap->a_vp);
           vprint("device vnode", ap->a_bp->b_vp);
           ap->a_bp->b_ioflags |= BIO_ERROR;
           ap->a_bp->b_error = EOPNOTSUPP;
           bufdone(ap->a_bp);
           return (EOPNOTSUPP);
   }
   
   /*
    * vop_stdpathconf:
    *
    * Standard implementation of POSIX pathconf, to get information about limits
    * for a filesystem.
    * Override per filesystem for the case where the filesystem has smaller
    * limits.
    */
   int
   vop_stdpathconf(ap)
           struct vop_pathconf_args /* {
           struct vnode *a_vp;
           int a_name;
           int *a_retval;
           } */ *ap;
   {
   
           switch (ap->a_name) {
                   case _PC_LINK_MAX:
                           *ap->a_retval = LINK_MAX;
                           return (0);
                   case _PC_MAX_CANON:
                           *ap->a_retval = MAX_CANON;
                           return (0);
                   case _PC_MAX_INPUT:
                           *ap->a_retval = MAX_INPUT;
                           return (0);
                   case _PC_PIPE_BUF:
                           *ap->a_retval = PIPE_BUF;
                           return (0);
                   case _PC_CHOWN_RESTRICTED:
                           *ap->a_retval = 1;
                           return (0);
                   case _PC_VDISABLE:
                           *ap->a_retval = _POSIX_VDISABLE;
                           return (0);
                   default:
                           return (EINVAL);
           }
           /* NOTREACHED */
   }
   
   /*
    * Standard lock, unlock and islocked functions.
    */
   int
   vop_stdlock(ap)
           struct vop_lock_args /* {
                   struct vnode *a_vp;
                   int a_flags;
                   struct thread *a_td;
           } */ *ap;
   {
           struct vnode *vp = ap->a_vp;
   
   #ifndef DEBUG_LOCKS
           return (lockmgr(vp->v_vnlock, ap->a_flags, VI_MTX(vp), ap->a_td));
   #else
           return (debuglockmgr(vp->v_vnlock, ap->a_flags, VI_MTX(vp),
               ap->a_td, "vop_stdlock", vp->filename, vp->line));
   #endif
   }
   
   /* See above. */
   int
   vop_stdunlock(ap)
           struct vop_unlock_args /* {
                   struct vnode *a_vp;
                   int a_flags;
                   struct thread *a_td;
           } */ *ap;
   {
           struct vnode *vp = ap->a_vp;
   
           return (lockmgr(vp->v_vnlock, ap->a_flags | LK_RELEASE, VI_MTX(vp),
               ap->a_td));
   }
   
   /* See above. */
   int
   vop_stdislocked(ap)
           struct vop_islocked_args /* {
                   struct vnode *a_vp;
                   struct thread *a_td;
           } */ *ap;
   {
   
           return (lockstatus(ap->a_vp->v_vnlock, ap->a_td));
   }
   
   /* Mark the vnode inactive */
   int
   vop_stdinactive(ap)
           struct vop_inactive_args /* {
                   struct vnode *a_vp;
                   struct thread *a_td;
           } */ *ap;
   {
   
           VOP_UNLOCK(ap->a_vp, 0, ap->a_td);
           return (0);
   }
   
   /*
    * Return true for select/poll.
    */
   int
   vop_nopoll(ap)
           struct vop_poll_args /* {
                   struct vnode *a_vp;
                   int  a_events;
                   struct ucred *a_cred;
                   struct thread *a_td;
           } */ *ap;
   {
           /*
            * Return true for read/write.  If the user asked for something
            * special, return POLLNVAL, so that clients have a way of
            * determining reliably whether or not the extended
            * functionality is present without hard-coding knowledge
            * of specific filesystem implementations.
            * Stay in sync with kern_conf.c::no_poll().
            */
           if (ap->a_events & ~POLLSTANDARD)
                   return (POLLNVAL);
   
           return (ap->a_events & (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM));
   }
   
   /*
    * Implement poll for local filesystems that support it.
    */
   int
   vop_stdpoll(ap)
           struct vop_poll_args /* {
                   struct vnode *a_vp;
                   int  a_events;
                   struct ucred *a_cred;
                   struct thread *a_td;
           } */ *ap;
   {
           if (ap->a_events & ~POLLSTANDARD)
                   return (vn_pollrecord(ap->a_vp, ap->a_td, ap->a_events));
           return (ap->a_events & (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM));
   }
   
   /*
    * Return our mount point, as we will take charge of the writes.
    */
   int
   vop_stdgetwritemount(ap)
           struct vop_getwritemount_args /* {
                   struct vnode *a_vp;
                   struct mount **a_mpp;
           } */ *ap;
   {
   
           *(ap->a_mpp) = ap->a_vp->v_mount;
           return (0);
   }
   
   /* Create the VM system backing object for this vnode */
   int
   vop_stdcreatevobject(ap)
           struct vop_createvobject_args /* {
                   struct vnode *vp;
                   struct ucred *cred;
                   struct thread *td;
           } */ *ap;
   {
           struct vnode *vp = ap->a_vp;
           struct ucred *cred = ap->a_cred;
           struct thread *td = ap->a_td;
           struct vattr vat;
           vm_object_t object;
           int error = 0;
   
           GIANT_REQUIRED;
   
           if (!vn_isdisk(vp, NULL) && vn_canvmio(vp) == FALSE)
                   return (0);
   
   retry:
           if ((object = vp->v_object) == NULL) {
                   if (vp->v_type == VREG || vp->v_type == VDIR) {
                           if ((error = VOP_GETATTR(vp, &vat, cred, td)) != 0)
                                   goto retn;
                           object = vnode_pager_alloc(vp, vat.va_size, 0, 0);
                   } else if (devsw(vp->v_rdev) != NULL) {
                           /*
                            * This simply allocates the biggest object possible
                            * for a disk vnode.  This should be fixed, but doesn't
                            * cause any problems (yet).
                            */
                           object = vnode_pager_alloc(vp, IDX_TO_OFF(INT_MAX), 0, 0);
                   } else {
                           goto retn;
                   }
                   /*
                    * Dereference the reference we just created.  This assumes
                    * that the object is associated with the vp.
                    */
                   VM_OBJECT_LOCK(object);
                   object->ref_count--;
                   VM_OBJECT_UNLOCK(object);
                   vrele(vp);
           } else {
                   VM_OBJECT_LOCK(object);
                   if (object->flags & OBJ_DEAD) {
                           VOP_UNLOCK(vp, 0, td);
                           msleep(object, VM_OBJECT_MTX(object), PDROP | PVM,
                               "vodead", 0);
                           vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
                           goto retry;
                   }
                   VM_OBJECT_UNLOCK(object);
           }
   
           KASSERT(vp->v_object != NULL, ("vfs_object_create: NULL object"));
           vp->v_vflag |= VV_OBJBUF;
   
   retn:
           return (error);
   }
   
   /* Destroy the VM system object associated with this vnode */
   int
   vop_stddestroyvobject(ap)
           struct vop_destroyvobject_args /* {
                   struct vnode *vp;
           } */ *ap;
   {
           struct vnode *vp = ap->a_vp;
           vm_object_t obj = vp->v_object;
   
           GIANT_REQUIRED;
   
           if (obj == NULL)
                   return (0);
           VM_OBJECT_LOCK(obj);
           if (obj->ref_count == 0) {
                   /*
                    * vclean() may be called twice. The first time
                    * removes the primary reference to the object,
                    * the second time goes one further and is a
                    * special-case to terminate the object.
                    *
                    * don't double-terminate the object
                    */
                   if ((obj->flags & OBJ_DEAD) == 0)
                           vm_object_terminate(obj);
                   else
                           VM_OBJECT_UNLOCK(obj);
           } else {
                   /*
                    * Woe to the process that tries to page now :-).
                    */
                   vm_pager_deallocate(obj);
                   VM_OBJECT_UNLOCK(obj);
           }
           return (0);
   }
   
   /*
    * Return the underlying VM object.  This routine may be called with or
    * without the vnode interlock held.  If called without, the returned
    * object is not guarenteed to be valid.  The syncer typically gets the
    * object without holding the interlock in order to quickly test whether
    * it might be dirty before going heavy-weight.  vm_object's use zalloc
    * and thus stable-storage, so this is safe.
    */
   int
   vop_stdgetvobject(ap)
           struct vop_getvobject_args /* {
                   struct vnode *vp;
                   struct vm_object **objpp;
           } */ *ap;
   {
           struct vnode *vp = ap->a_vp;
           struct vm_object **objpp = ap->a_objpp;
   
           if (objpp)
                   *objpp = vp->v_object;
           return (vp->v_object ? 0 : EINVAL);
   }
   
   /* XXX Needs good comment and VOP_BMAP(9) manpage */
   int
   vop_stdbmap(ap)
           struct vop_bmap_args /* {
                   struct vnode *a_vp;
                   daddr_t  a_bn;
                   struct vnode **a_vpp;
                   daddr_t *a_bnp;
                   int *a_runp;
                   int *a_runb;
           } */ *ap;
   {
   
           if (ap->a_vpp != NULL)
                   *ap->a_vpp = ap->a_vp;
           if (ap->a_bnp != NULL)
                   *ap->a_bnp = ap->a_bn * btodb(ap->a_vp->v_mount->mnt_stat.f_iosize);
           if (ap->a_runp != NULL)
                   *ap->a_runp = 0;
           if (ap->a_runb != NULL)
                   *ap->a_runb = 0;
           return (0);
   }
   
   int
   vop_stdfsync(ap)
           struct vop_fsync_args /* {
                   struct vnode *a_vp;
                   struct ucred *a_cred;
                   int a_waitfor;
                   struct thread *a_td;
           } */ *ap;
   {
           struct vnode *vp = ap->a_vp;
           struct buf *bp;
           struct buf *nbp;
           int s, error = 0;
           int maxretry = 100;     /* large, arbitrarily chosen */
   
           VI_LOCK(vp);
   loop1:
           /*
            * MARK/SCAN initialization to avoid infinite loops.
            */
           s = splbio();
           TAILQ_FOREACH(bp, &vp->v_dirtyblkhd, b_vnbufs) {
                   bp->b_vflags &= ~BV_SCANNED;
                   bp->b_error = 0;
           }
           splx(s);
   
           /*
            * Flush all dirty buffers associated with a block device.
            */
   loop2:
           s = splbio();
           for (bp = TAILQ_FIRST(&vp->v_dirtyblkhd); bp != NULL; bp = nbp) {
                   nbp = TAILQ_NEXT(bp, b_vnbufs);
                   if ((bp->b_vflags & BV_SCANNED) != 0)
                           continue;
                   bp->b_vflags |= BV_SCANNED;
                   if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL))
                           continue;
                   VI_UNLOCK(vp);
                   if ((bp->b_flags & B_DELWRI) == 0)
                           panic("fsync: not dirty");
                   if ((vp->v_vflag & VV_OBJBUF) && (bp->b_flags & B_CLUSTEROK)) {
                           vfs_bio_awrite(bp);
                           splx(s);
                   } else {
                           bremfree(bp);
                           splx(s);
                           bawrite(bp);
                   }
                   VI_LOCK(vp);
                   goto loop2;
           }
   
           /*
            * If synchronous the caller expects us to completely resolve all
            * dirty buffers in the system.  Wait for in-progress I/O to
            * complete (which could include background bitmap writes), then
            * retry if dirty blocks still exist.
            */
           if (ap->a_waitfor == MNT_WAIT) {
                   while (vp->v_numoutput) {
                           vp->v_iflag |= VI_BWAIT;
                           msleep((caddr_t)&vp->v_numoutput, VI_MTX(vp),
                               PRIBIO + 1, "fsync", 0);
                   }
                   if (!TAILQ_EMPTY(&vp->v_dirtyblkhd)) {
                           /*
                            * If we are unable to write any of these buffers
                            * then we fail now rather than trying endlessly
                            * to write them out.
                            */
                           TAILQ_FOREACH(bp, &vp->v_dirtyblkhd, b_vnbufs)
                                   if ((error = bp->b_error) == 0)
                                           continue;
                           if (error == 0 && --maxretry >= 0) {
                                   splx(s);
                                   goto loop1;
                           }
                           vprint("fsync: giving up on dirty", vp);
                           error = EAGAIN;
                   }
           }
           VI_UNLOCK(vp);
           splx(s);
   
           return (error);
   }
   
   /* XXX Needs good comment and more info in the manpage (VOP_GETPAGES(9)). */
   int
   vop_stdgetpages(ap)
           struct vop_getpages_args /* {
                   struct vnode *a_vp;
                   vm_page_t *a_m;
                   int a_count;
                   int a_reqpage;
                   vm_ooffset_t a_offset;
           } */ *ap;
   {
   
           return vnode_pager_generic_getpages(ap->a_vp, ap->a_m,
               ap->a_count, ap->a_reqpage);
   }
   
   /* XXX Needs good comment and more info in the manpage (VOP_PUTPAGES(9)). */
   int
   vop_stdputpages(ap)
           struct vop_putpages_args /* {
                   struct vnode *a_vp;
                   vm_page_t *a_m;
                   int a_count;
                   int a_sync;
                   int *a_rtvals;
                   vm_ooffset_t a_offset;
           } */ *ap;
   {
   
           return vnode_pager_generic_putpages(ap->a_vp, ap->a_m, ap->a_count,
                ap->a_sync, ap->a_rtvals);
   }
   
   /*
    * vfs default ops
    * used to fill the vfs function table to get reasonable default return values.
    */
   int
   vfs_stdroot (mp, vpp, td)
           struct mount *mp;
           struct vnode **vpp;
           struct thread *td;
   {
   
           return (EOPNOTSUPP);
   }
   
   int
   vfs_stdstatfs (mp, sbp, td)
           struct mount *mp;
           struct statfs *sbp;
           struct thread *td;
   {
   
           return (EOPNOTSUPP);
   }
   
   int
   vfs_stdvptofh (vp, fhp)
           struct vnode *vp;
           struct fid *fhp;
   {
   
           return (EOPNOTSUPP);
   }
   
   int
   vfs_stdstart (mp, flags, td)
           struct mount *mp;
           int flags;
           struct thread *td;
   {
   
           return (0);
   }
   
   int
   vfs_stdquotactl (mp, cmds, uid, arg, td)
           struct mount *mp;
           int cmds;
           uid_t uid;
           caddr_t arg;
           struct thread *td;
   {
   
           return (EOPNOTSUPP);
   }
   
   int
   vfs_stdsync(mp, waitfor, cred, td)
           struct mount *mp;
           int waitfor;
           struct ucred *cred;
           struct thread *td;
   {
           struct vnode *vp, *nvp;
           int error, lockreq, allerror = 0;
   
           lockreq = LK_EXCLUSIVE | LK_INTERLOCK;
           if (waitfor != MNT_WAIT)
                   lockreq |= LK_NOWAIT;
           /*
            * Force stale buffer cache information to be flushed.
            */
           MNT_ILOCK(mp);
   loop:
           MNT_VNODE_FOREACH(vp, mp, nvp) {
   
                   VI_LOCK(vp);
                   if (TAILQ_EMPTY(&vp->v_dirtyblkhd)) {
                           VI_UNLOCK(vp);
                           continue;
                   }
                   MNT_IUNLOCK(mp);
   
                   if ((error = vget(vp, lockreq, td)) != 0) {
                           MNT_ILOCK(mp);
                           if (error == ENOENT)
                                   goto loop;
                           continue;
                   }
                   error = VOP_FSYNC(vp, cred, waitfor, td);
                   if (error)
                           allerror = error;
   
                   VOP_UNLOCK(vp, 0, td);
                   vrele(vp);
                   MNT_ILOCK(mp);
           }
           MNT_IUNLOCK(mp);
           return (allerror);
   }
   
   int
   vfs_stdnosync (mp, waitfor, cred, td)
           struct mount *mp;
           int waitfor;
           struct ucred *cred;
           struct thread *td;
   {
   
           return (0);
   }
   
   int
   vfs_stdvget (mp, ino, flags, vpp)
           struct mount *mp;
           ino_t ino;
           int flags;
           struct vnode **vpp;
   {
   
           return (EOPNOTSUPP);
   }
   
   int
   vfs_stdfhtovp (mp, fhp, vpp)
           struct mount *mp;
           struct fid *fhp;
           struct vnode **vpp;
   {
   
           return (EOPNOTSUPP);
   }
   
   int
   vfs_stdinit (vfsp)
           struct vfsconf *vfsp;
   {
   
           return (0);
   }
   
   int
   vfs_stduninit (vfsp)
           struct vfsconf *vfsp;
   {
   
           return(0);
   }
   
   int
   vfs_stdextattrctl(mp, cmd, filename_vp, attrnamespace, attrname, td)
           struct mount *mp;
           int cmd;
           struct vnode *filename_vp;
           int attrnamespace;
           const char *attrname;
           struct thread *td;
   {
   
           if (filename_vp != NULL)
                   VOP_UNLOCK(filename_vp, 0, td);
           return (EOPNOTSUPP);
   }
   
   int
   vfs_stdsysctl(mp, op, req)
           struct mount *mp;
           fsctlop_t op;
           struct sysctl_req *req;
   {
   
           return (EOPNOTSUPP);
   }
   
   /* end of vfs default ops */

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