vfs_default.c

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/*-
 * 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("$BSDSUniX$");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/conf.h>
#include <sys/event.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/lockf.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/namei.h>
#include <sys/fcntl.h>
#include <sys/unistd.h>
#include <sys/vnode.h>
#include <sys/dirent.h>
#include <sys/poll.h>

#include <security/mac/mac_framework.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_norename(struct vop_rename_args *);
static int      vop_nostrategy(struct vop_strategy_args *);
static int      get_next_dirent(struct vnode *vp, struct dirent **dpp,
                                char *dirbuf, int dirbuflen, off_t *off,
                                char **cpos, int *len, int *eofflag,
                                struct thread *td);
static int      dirent_exists(struct vnode *vp, const char *dirname,
                              struct thread *td);

#define DIRENT_MINSIZE (sizeof(struct dirent) - (MAXNAMLEN+1) + 4)

static int vop_stdis_text(struct vop_is_text_args *ap);
static int vop_stdset_text(struct vop_set_text_args *ap);
static int vop_stdunset_text(struct vop_unset_text_args *ap);
static int vop_stdget_writecount(struct vop_get_writecount_args *ap);
static int vop_stdadd_writecount(struct vop_add_writecount_args *ap);

/*
 * 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.
 *
 * Note that every filesystem has to implement either vop_access
 * or vop_accessx; failing to do so will result in immediate crash
 * due to stack overflow, as vop_stdaccess() calls vop_stdaccessx(),
 * which calls vop_stdaccess() etc.
 */

struct vop_vector default_vnodeops = {
        .vop_default =          NULL,
        .vop_bypass =           VOP_EOPNOTSUPP,

        .vop_access =           vop_stdaccess,
        .vop_accessx =          vop_stdaccessx,
        .vop_advise =           vop_stdadvise,
        .vop_advlock =          vop_stdadvlock,
        .vop_advlockasync =     vop_stdadvlockasync,
        .vop_advlockpurge =     vop_stdadvlockpurge,
        .vop_allocate =         vop_stdallocate,
        .vop_bmap =             vop_stdbmap,
        .vop_close =            VOP_NULL,
        .vop_fsync =            VOP_NULL,
        .vop_getpages =         vop_stdgetpages,
        .vop_getwritemount =    vop_stdgetwritemount,
        .vop_inactive =         VOP_NULL,
        .vop_ioctl =            VOP_ENOTTY,
        .vop_kqfilter =         vop_stdkqfilter,
        .vop_islocked =         vop_stdislocked,
        .vop_lock1 =            vop_stdlock,
        .vop_lookup =           vop_nolookup,
        .vop_open =             VOP_NULL,
        .vop_pathconf =         VOP_EINVAL,
        .vop_poll =             vop_nopoll,
        .vop_putpages =         vop_stdputpages,
        .vop_readlink =         VOP_EINVAL,
        .vop_rename =           vop_norename,
        .vop_revoke =           VOP_PANIC,
        .vop_strategy =         vop_nostrategy,
        .vop_unlock =           vop_stdunlock,
        .vop_vptocnp =          vop_stdvptocnp,
        .vop_vptofh =           vop_stdvptofh,
        .vop_unp_bind =         vop_stdunp_bind,
        .vop_unp_connect =      vop_stdunp_connect,
        .vop_unp_detach =       vop_stdunp_detach,
        .vop_is_text =          vop_stdis_text,
        .vop_set_text =         vop_stdset_text,
        .vop_unset_text =       vop_stdunset_text,
        .vop_get_writecount =   vop_stdget_writecount,
        .vop_add_writecount =   vop_stdadd_writecount,
};

/*
 * 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_enoent(struct vop_generic_args *ap)
{

        return (ENOENT);
}

int
vop_null(struct vop_generic_args *ap)
{

        return (0);
}

/*
 * 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_norename:
 *
 * Handle unlock and reference counting for arguments of vop_rename
 * for filesystems that do not implement rename operation.
 */
static int
vop_norename(struct vop_rename_args *ap)
{

        vop_rename_fail(ap);
        return (EOPNOTSUPP);
}

/*
 *      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)
{
        printf("No strategy for buffer at %p\n", ap->a_bp);
        vprint("vnode", ap->a_vp);
        ap->a_bp->b_ioflags |= BIO_ERROR;
        ap->a_bp->b_error = EOPNOTSUPP;
        bufdone(ap->a_bp);
        return (EOPNOTSUPP);
}

static int
get_next_dirent(struct vnode *vp, struct dirent **dpp, char *dirbuf,
                int dirbuflen, off_t *off, char **cpos, int *len,
                int *eofflag, struct thread *td)
{
        int error, reclen;
        struct uio uio;
        struct iovec iov;
        struct dirent *dp;

        KASSERT(VOP_ISLOCKED(vp), ("vp %p is not locked", vp));
        KASSERT(vp->v_type == VDIR, ("vp %p is not a directory", vp));

        if (*len == 0) {
                iov.iov_base = dirbuf;
                iov.iov_len = dirbuflen;

                uio.uio_iov = &iov;
                uio.uio_iovcnt = 1;
                uio.uio_offset = *off;
                uio.uio_resid = dirbuflen;
                uio.uio_segflg = UIO_SYSSPACE;
                uio.uio_rw = UIO_READ;
                uio.uio_td = td;

                *eofflag = 0;

#ifdef MAC
                error = mac_vnode_check_readdir(td->td_ucred, vp);
                if (error == 0)
#endif
                        error = VOP_READDIR(vp, &uio, td->td_ucred, eofflag,
                                NULL, NULL);
                if (error)
                        return (error);

                *off = uio.uio_offset;

                *cpos = dirbuf;
                *len = (dirbuflen - uio.uio_resid);

                if (*len == 0)
                        return (ENOENT);
        }

        dp = (struct dirent *)(*cpos);
        reclen = dp->d_reclen;
        *dpp = dp;

        /* check for malformed directory.. */
        if (reclen < DIRENT_MINSIZE)
                return (EINVAL);

        *cpos += reclen;
        *len -= reclen;

        return (0);
}

/*
 * Check if a named file exists in a given directory vnode.
 */
static int
dirent_exists(struct vnode *vp, const char *dirname, struct thread *td)
{
        char *dirbuf, *cpos;
        int error, eofflag, dirbuflen, len, found;
        off_t off;
        struct dirent *dp;
        struct vattr va;

        KASSERT(VOP_ISLOCKED(vp), ("vp %p is not locked", vp));
        KASSERT(vp->v_type == VDIR, ("vp %p is not a directory", vp));

        found = 0;

        error = VOP_GETATTR(vp, &va, td->td_ucred);
        if (error)
                return (found);

        dirbuflen = DEV_BSIZE;
        if (dirbuflen < va.va_blocksize)
                dirbuflen = va.va_blocksize;
        dirbuf = (char *)malloc(dirbuflen, M_TEMP, M_WAITOK);

        off = 0;
        len = 0;
        do {
                error = get_next_dirent(vp, &dp, dirbuf, dirbuflen, &off,
                                        &cpos, &len, &eofflag, td);
                if (error)
                        goto out;

                if ((dp->d_type != DT_WHT) &&
                    !strcmp(dp->d_name, dirname)) {
                        found = 1;
                        goto out;
                }
        } while (len > 0 || !eofflag);

out:
        free(dirbuf, M_TEMP);
        return (found);
}

int
vop_stdaccess(struct vop_access_args *ap)
{

        KASSERT((ap->a_accmode & ~(VEXEC | VWRITE | VREAD | VADMIN |
            VAPPEND)) == 0, ("invalid bit in accmode"));

        return (VOP_ACCESSX(ap->a_vp, ap->a_accmode, ap->a_cred, ap->a_td));
}

int
vop_stdaccessx(struct vop_accessx_args *ap)
{
        int error;
        accmode_t accmode = ap->a_accmode;

        error = vfs_unixify_accmode(&accmode);
        if (error != 0)
                return (error);

        if (accmode == 0)
                return (0);

        return (VOP_ACCESS(ap->a_vp, accmode, ap->a_cred, ap->a_td));
}

/*
 * Advisory record locking support
 */
int
vop_stdadvlock(struct vop_advlock_args *ap)
{
        struct vnode *vp;
        struct vattr vattr;
        int error;

        vp = ap->a_vp;
        if (ap->a_fl->l_whence == SEEK_END) {
                /*
                 * The NFSv4 server must avoid doing a vn_lock() here, since it
                 * can deadlock the nfsd threads, due to a LOR.  Fortunately
                 * the NFSv4 server always uses SEEK_SET and this code is
                 * only required for the SEEK_END case.
                 */
                vn_lock(vp, LK_SHARED | LK_RETRY);
                error = VOP_GETATTR(vp, &vattr, curthread->td_ucred);
                VOP_UNLOCK(vp, 0);
                if (error)
                        return (error);
        } else
                vattr.va_size = 0;

        return (lf_advlock(ap, &(vp->v_lockf), vattr.va_size));
}

int
vop_stdadvlockasync(struct vop_advlockasync_args *ap)
{
        struct vnode *vp;
        struct vattr vattr;
        int error;

        vp = ap->a_vp;
        if (ap->a_fl->l_whence == SEEK_END) {
                /* The size argument is only needed for SEEK_END. */
                vn_lock(vp, LK_SHARED | LK_RETRY);
                error = VOP_GETATTR(vp, &vattr, curthread->td_ucred);
                VOP_UNLOCK(vp, 0);
                if (error)
                        return (error);
        } else
                vattr.va_size = 0;

        return (lf_advlockasync(ap, &(vp->v_lockf), vattr.va_size));
}

int
vop_stdadvlockpurge(struct vop_advlockpurge_args *ap)
{
        struct vnode *vp;

        vp = ap->a_vp;
        lf_purgelocks(vp, &vp->v_lockf);
        return (0);
}

/*
 * 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_NAME_MAX:
                        *ap->a_retval = NAME_MAX;
                        return (0);
                case _PC_PATH_MAX:
                        *ap->a_retval = PATH_MAX;
                        return (0);
                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_lock1_args /* {
                struct vnode *a_vp;
                int a_flags;
                char *file;
                int line;
        } */ *ap;
{
        struct vnode *vp = ap->a_vp;

        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));
}

/* See above. */
int
vop_stdunlock(ap)
        struct vop_unlock_args /* {
                struct vnode *a_vp;
                int a_flags;
        } */ *ap;
{
        struct vnode *vp = ap->a_vp;

        return (lockmgr(vp->v_vnlock, ap->a_flags | LK_RELEASE, VI_MTX(vp)));
}

/* See above. */
int
vop_stdislocked(ap)
        struct vop_islocked_args /* {
                struct vnode *a_vp;
        } */ *ap;
{

        return (lockstatus(ap->a_vp->v_vnlock));
}

/*
 * 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 (poll_no_poll(ap->a_events));
}

/*
 * 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;
{
        struct mount *mp;

        /*
         * XXX Since this is called unlocked we may be recycled while
         * attempting to ref the mount.  If this is the case or mountpoint
         * will be set to NULL.  We only have to prevent this call from
         * returning with a ref to an incorrect mountpoint.  It is not
         * harmful to return with a ref to our previous mountpoint.
         */
        mp = ap->a_vp->v_mount;
        if (mp != NULL) {
                vfs_ref(mp);
                if (mp != ap->a_vp->v_mount) {
                        vfs_rel(mp);
                        mp = NULL;
                }
        }
        *(ap->a_mpp) = mp;
        return (0);
}

/* 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 bufobj **a_bop;
                daddr_t *a_bnp;
                int *a_runp;
                int *a_runb;
        } */ *ap;
{

        if (ap->a_bop != NULL)
                *ap->a_bop = &ap->a_vp->v_bufobj;
        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 bufobj *bo;
        struct buf *nbp;
        int error = 0;
        int maxretry = 1000;     /* large, arbitrarily chosen */

        bo = &vp->v_bufobj;
        BO_LOCK(bo);
loop1:
        /*
         * MARK/SCAN initialization to avoid infinite loops.
         */
        TAILQ_FOREACH(bp, &bo->bo_dirty.bv_hd, b_bobufs) {
                bp->b_vflags &= ~BV_SCANNED;
                bp->b_error = 0;
        }

        /*
         * Flush all dirty buffers associated with a vnode.
         */
loop2:
        TAILQ_FOREACH_SAFE(bp, &bo->bo_dirty.bv_hd, b_bobufs, nbp) {
                if ((bp->b_vflags & BV_SCANNED) != 0)
                        continue;
                bp->b_vflags |= BV_SCANNED;
                if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL)) {
                        if (ap->a_waitfor != MNT_WAIT)
                                continue;
                        if (BUF_LOCK(bp,
                            LK_EXCLUSIVE | LK_INTERLOCK | LK_SLEEPFAIL,
                            BO_MTX(bo)) != 0) {
                                BO_LOCK(bo);
                                goto loop1;
                        }
                        BO_LOCK(bo);
                }
                BO_UNLOCK(bo);
                KASSERT(bp->b_bufobj == bo,
                    ("bp %p wrong b_bufobj %p should be %p",
                    bp, bp->b_bufobj, bo));
                if ((bp->b_flags & B_DELWRI) == 0)
                        panic("fsync: not dirty");
                if ((vp->v_object != NULL) && (bp->b_flags & B_CLUSTEROK)) {
                        vfs_bio_awrite(bp);
                } else {
                        bremfree(bp);
                        bawrite(bp);
                }
                BO_LOCK(bo);
                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) {
                bufobj_wwait(bo, 0, 0);
                if (bo->bo_dirty.bv_cnt > 0) {
                        /*
                         * 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, &bo->bo_dirty.bv_hd, b_bobufs)
                                if ((error = bp->b_error) == 0)
                                        continue;
                        if (error == 0 && --maxretry >= 0)
                                goto loop1;
                        error = EAGAIN;
                }
        }
        BO_UNLOCK(bo);
        if (error == EAGAIN)
                vprint("fsync: giving up on dirty", vp);

        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);
}

int
vop_stdkqfilter(struct vop_kqfilter_args *ap)
{
        return vfs_kqfilter(ap);
}

/* 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);
}

int
vop_stdvptofh(struct vop_vptofh_args *ap)
{
        return (EOPNOTSUPP);
}

int
vop_stdvptocnp(struct vop_vptocnp_args *ap)
{
        struct vnode *vp = ap->a_vp;
        struct vnode **dvp = ap->a_vpp;
        struct ucred *cred = ap->a_cred;
        char *buf = ap->a_buf;
        int *buflen = ap->a_buflen;
        char *dirbuf, *cpos;
        int i, error, eofflag, dirbuflen, flags, locked, len, covered;
        off_t off;
        ino_t fileno;
        struct vattr va;
        struct nameidata nd;
        struct thread *td;
        struct dirent *dp;
        struct vnode *mvp;

        i = *buflen;
        error = 0;
        covered = 0;
        td = curthread;

        if (vp->v_type != VDIR)
                return (ENOENT);

        error = VOP_GETATTR(vp, &va, cred);
        if (error)
                return (error);

        VREF(vp);
        locked = VOP_ISLOCKED(vp);
        VOP_UNLOCK(vp, 0);
        NDINIT_ATVP(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE,
            "..", vp, td);
        flags = FREAD;
        error = vn_open_cred(&nd, &flags, 0, VN_OPEN_NOAUDIT, cred, NULL);
        if (error) {
                vn_lock(vp, locked | LK_RETRY);
                return (error);
        }
        NDFREE(&nd, NDF_ONLY_PNBUF);

        mvp = *dvp = nd.ni_vp;

        if (vp->v_mount != (*dvp)->v_mount &&
            ((*dvp)->v_vflag & VV_ROOT) &&
            ((*dvp)->v_mount->mnt_flag & MNT_UNION)) {
                *dvp = (*dvp)->v_mount->mnt_vnodecovered;
                VREF(mvp);
                VOP_UNLOCK(mvp, 0);
                vn_close(mvp, FREAD, cred, td);
                VREF(*dvp);
                vn_lock(*dvp, LK_EXCLUSIVE | LK_RETRY);
                covered = 1;
        }

        fileno = va.va_fileid;

        dirbuflen = DEV_BSIZE;
        if (dirbuflen < va.va_blocksize)
                dirbuflen = va.va_blocksize;
        dirbuf = (char *)malloc(dirbuflen, M_TEMP, M_WAITOK);

        if ((*dvp)->v_type != VDIR) {
                error = ENOENT;
                goto out;
        }

        off = 0;
        len = 0;
        do {
                /* call VOP_READDIR of parent */
                error = get_next_dirent(*dvp, &dp, dirbuf, dirbuflen, &off,
                                        &cpos, &len, &eofflag, td);
                if (error)
                        goto out;

                if ((dp->d_type != DT_WHT) &&
                    (dp->d_fileno == fileno)) {
                        if (covered) {
                                VOP_UNLOCK(*dvp, 0);
                                vn_lock(mvp, LK_EXCLUSIVE | LK_RETRY);
                                if (dirent_exists(mvp, dp->d_name, td)) {
                                        error = ENOENT;
                                        VOP_UNLOCK(mvp, 0);
                                        vn_lock(*dvp, LK_EXCLUSIVE | LK_RETRY);
                                        goto out;
                                }
                                VOP_UNLOCK(mvp, 0);
                                vn_lock(*dvp, LK_EXCLUSIVE | LK_RETRY);
                        }
                        i -= dp->d_namlen;

                        if (i < 0) {
                                error = ENOMEM;
                                goto out;
                        }
                        if (dp->d_namlen == 1 && dp->d_name[0] == '.') {
                                error = ENOENT;
                        } else {
                                bcopy(dp->d_name, buf + i, dp->d_namlen);
                                error = 0;
                        }
                        goto out;
                }
        } while (len > 0 || !eofflag);
        error = ENOENT;

out:
        free(dirbuf, M_TEMP);
        if (!error) {
                *buflen = i;
                vref(*dvp);
        }
        if (covered) {
                vput(*dvp);
                vrele(mvp);
        } else {
                VOP_UNLOCK(mvp, 0);
                vn_close(mvp, FREAD, cred, td);
        }
        vn_lock(vp, locked | LK_RETRY);
        return (error);
}

int
vop_stdallocate(struct vop_allocate_args *ap)
{
#ifdef __notyet__
        struct statfs sfs;
#endif
        struct iovec aiov;
        struct vattr vattr, *vap;
        struct uio auio;
        off_t fsize, len, cur, offset;
        uint8_t *buf;
        struct thread *td;
        struct vnode *vp;
        size_t iosize;
        int error;

        buf = NULL;
        error = 0;
        td = curthread;
        vap = &vattr;
        vp = ap->a_vp;
        len = *ap->a_len;
        offset = *ap->a_offset;

        error = VOP_GETATTR(vp, vap, td->td_ucred);
        if (error != 0)
                goto out;
        fsize = vap->va_size;
        iosize = vap->va_blocksize;
        if (iosize == 0)
                iosize = BLKDEV_IOSIZE;
        if (iosize > MAXPHYS)
                iosize = MAXPHYS;
        buf = malloc(iosize, M_TEMP, M_WAITOK);

#ifdef __notyet__
        /*
         * Check if the filesystem sets f_maxfilesize; if not use
         * VOP_SETATTR to perform the check.
         */
        error = VFS_STATFS(vp->v_mount, &sfs, td);
        if (error != 0)
                goto out;
        if (sfs.f_maxfilesize) {
                if (offset > sfs.f_maxfilesize || len > sfs.f_maxfilesize ||
                    offset + len > sfs.f_maxfilesize) {
                        error = EFBIG;
                        goto out;
                }
        } else
#endif
        if (offset + len > vap->va_size) {
                /*
                 * Test offset + len against the filesystem's maxfilesize.
                 */
                VATTR_NULL(vap);
                vap->va_size = offset + len;
                error = VOP_SETATTR(vp, vap, td->td_ucred);
                if (error != 0)
                        goto out;
                VATTR_NULL(vap);
                vap->va_size = fsize;
                error = VOP_SETATTR(vp, vap, td->td_ucred);
                if (error != 0)
                        goto out;
        }

        for (;;) {
                /*
                 * Read and write back anything below the nominal file
                 * size.  There's currently no way outside the filesystem
                 * to know whether this area is sparse or not.
                 */
                cur = iosize;
                if ((offset % iosize) != 0)
                        cur -= (offset % iosize);
                if (cur > len)
                        cur = len;
                if (offset < fsize) {
                        aiov.iov_base = buf;
                        aiov.iov_len = cur;
                        auio.uio_iov = &aiov;
                        auio.uio_iovcnt = 1;
                        auio.uio_offset = offset;
                        auio.uio_resid = cur;
                        auio.uio_segflg = UIO_SYSSPACE;
                        auio.uio_rw = UIO_READ;
                        auio.uio_td = td;
                        error = VOP_READ(vp, &auio, 0, td->td_ucred);
                        if (error != 0)
                                break;
                        if (auio.uio_resid > 0) {
                                bzero(buf + cur - auio.uio_resid,
                                    auio.uio_resid);
                        }
                } else {
                        bzero(buf, cur);
                }

                aiov.iov_base = buf;
                aiov.iov_len = cur;
                auio.uio_iov = &aiov;
                auio.uio_iovcnt = 1;
                auio.uio_offset = offset;
                auio.uio_resid = cur;
                auio.uio_segflg = UIO_SYSSPACE;
                auio.uio_rw = UIO_WRITE;
                auio.uio_td = td;

                error = VOP_WRITE(vp, &auio, 0, td->td_ucred);
                if (error != 0)
                        break;

                len -= cur;
                offset += cur;
                if (len == 0)
                        break;
                if (should_yield())
                        break;
        }

 out:
        *ap->a_len = len;
        *ap->a_offset = offset;
        free(buf, M_TEMP);
        return (error);
}

int
vop_stdadvise(struct vop_advise_args *ap)
{
        struct vnode *vp;
        off_t start, end;
        int error, vfslocked;

        vp = ap->a_vp;
        switch (ap->a_advice) {
        case POSIX_FADV_WILLNEED:
                /*
                 * Do nothing for now.  Filesystems should provide a
                 * custom method which starts an asynchronous read of
                 * the requested region.
                 */
                error = 0;
                break;
        case POSIX_FADV_DONTNEED:
                /*
                 * Flush any open FS buffers and then remove pages
                 * from the backing VM object.  Using vinvalbuf() here
                 * is a bit heavy-handed as it flushes all buffers for
                 * the given vnode, not just the buffers covering the
                 * requested range.
                 */
                error = 0;
                vfslocked = VFS_LOCK_GIANT(vp->v_mount);
                vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                if (vp->v_iflag & VI_DOOMED) {
                        VOP_UNLOCK(vp, 0);
                        VFS_UNLOCK_GIANT(vfslocked);
                        break;
                }
                vinvalbuf(vp, V_CLEANONLY, 0, 0);
                if (vp->v_object != NULL) {
                        start = trunc_page(ap->a_start);
                        end = round_page(ap->a_end);
                        VM_OBJECT_LOCK(vp->v_object);
                        vm_object_page_cache(vp->v_object, OFF_TO_IDX(start),
                            OFF_TO_IDX(end));
                        VM_OBJECT_UNLOCK(vp->v_object);
                }
                VOP_UNLOCK(vp, 0);
                VFS_UNLOCK_GIANT(vfslocked);
                break;
        default:
                error = EINVAL;
                break;
        }
        return (error);
}

int
vop_stdunp_bind(struct vop_unp_bind_args *ap)
{

        ap->a_vp->v_socket = ap->a_socket;
        return (0);
}

int
vop_stdunp_connect(struct vop_unp_connect_args *ap)
{

        *ap->a_socket = ap->a_vp->v_socket;
        return (0);
}

int
vop_stdunp_detach(struct vop_unp_detach_args *ap)
{

        ap->a_vp->v_socket = NULL;
        return (0);
}

static int
vop_stdis_text(struct vop_is_text_args *ap)
{

        return ((ap->a_vp->v_vflag & VV_TEXT) != 0);
}

static int
vop_stdset_text(struct vop_set_text_args *ap)
{

        ap->a_vp->v_vflag |= VV_TEXT;
        return (0);
}

static int
vop_stdunset_text(struct vop_unset_text_args *ap)
{

        ap->a_vp->v_vflag &= ~VV_TEXT;
        return (0);
}

static int
vop_stdget_writecount(struct vop_get_writecount_args *ap)
{

        *ap->a_writecount = ap->a_vp->v_writecount;
        return (0);
}

static int
vop_stdadd_writecount(struct vop_add_writecount_args *ap)
{

        ap->a_vp->v_writecount += ap->a_inc;
        return (0);
}

/*
 * vfs default ops
 * used to fill the vfs function table to get reasonable default return values.
 */
int
vfs_stdroot (mp, flags, vpp)
        struct mount *mp;
        int flags;
        struct vnode **vpp;
{

        return (EOPNOTSUPP);
}

int
vfs_stdstatfs (mp, sbp)
        struct mount *mp;
        struct statfs *sbp;
{

        return (EOPNOTSUPP);
}

int
vfs_stdquotactl (mp, cmds, uid, arg)
        struct mount *mp;
        int cmds;
        uid_t uid;
        void *arg;
{

        return (EOPNOTSUPP);
}

int
vfs_stdsync(mp, waitfor)
        struct mount *mp;
        int waitfor;
{
        struct vnode *vp, *mvp;
        struct thread *td;
        int error, lockreq, allerror = 0;

        td = curthread;
        lockreq = LK_EXCLUSIVE | LK_INTERLOCK;
        if (waitfor != MNT_WAIT)
                lockreq |= LK_NOWAIT;
        /*
         * Force stale buffer cache information to be flushed.
         */
loop:
        MNT_VNODE_FOREACH_ALL(vp, mp, mvp) {
                if (vp->v_bufobj.bo_dirty.bv_cnt == 0) {
                        VI_UNLOCK(vp);
                        continue;
                }
                if ((error = vget(vp, lockreq, td)) != 0) {
                        if (error == ENOENT) {
                                MNT_VNODE_FOREACH_ALL_ABORT(mp, mvp);
                                goto loop;
                        }
                        continue;
                }
                error = VOP_FSYNC(vp, waitfor, td);
                if (error)
                        allerror = error;
                vput(vp);
        }
        return (allerror);
}

int
vfs_stdnosync (mp, waitfor)
        struct mount *mp;
        int waitfor;
{

        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, flags, vpp)
        struct mount *mp;
        struct fid *fhp;
        int flags;
        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)
        struct mount *mp;
        int cmd;
        struct vnode *filename_vp;
        int attrnamespace;
        const char *attrname;
{

        if (filename_vp != NULL)
                VOP_UNLOCK(filename_vp, 0);
        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 */