/*
 * Mount a pseudofs instance
 */
int
pfs_mount(struct pfs_info *pi, struct mount *mp)
{
	struct statfs *sbp;

	if (mp->mnt_flag & MNT_UPDATE)
		return (EOPNOTSUPP);

	MNT_ILOCK(mp);
	mp->mnt_flag |= MNT_LOCAL;
	mp->mnt_kern_flag |= MNTK_MPSAFE;
	MNT_IUNLOCK(mp);
	mp->mnt_data = pi;
	vfs_getnewfsid(mp);

	sbp = &mp->mnt_stat;
	vfs_mountedfrom(mp, pi->pi_name);
	sbp->f_bsize = PAGE_SIZE;
	sbp->f_iosize = PAGE_SIZE;
	sbp->f_blocks = 1;
	sbp->f_bfree = 0;
	sbp->f_bavail = 0;
	sbp->f_files = 1;
	sbp->f_ffree = 0;

	return (0);
}

void
vfs_setmntopt(vfs_t *vfsp, const char *name, const char *arg,
    int flags __unused)
{
	struct vfsopt *opt;
	size_t namesize;
	int locked;

	if (!(locked = mtx_owned(MNT_MTX(vfsp))))
		MNT_ILOCK(vfsp);

	if (vfsp->mnt_opt == NULL) {
		void *opts;

		MNT_IUNLOCK(vfsp);
		opts = malloc(sizeof(*vfsp->mnt_opt), M_MOUNT, M_WAITOK);
		MNT_ILOCK(vfsp);
		if (vfsp->mnt_opt == NULL) {
			vfsp->mnt_opt = opts;
			TAILQ_INIT(vfsp->mnt_opt);
		} else {
			free(opts, M_MOUNT);
		}
	}

	MNT_IUNLOCK(vfsp);

	opt = malloc(sizeof(*opt), M_MOUNT, M_WAITOK);
	namesize = strlen(name) + 1;
	opt->name = malloc(namesize, M_MOUNT, M_WAITOK);
	strlcpy(opt->name, name, namesize);
	opt->pos = -1;
	opt->seen = 1;
	if (arg == NULL) {
		opt->value = NULL;
		opt->len = 0;
	} else {
		opt->len = strlen(arg) + 1;
		opt->value = malloc(opt->len, M_MOUNT, M_WAITOK);
		bcopy(arg, opt->value, opt->len);
	}

	MNT_ILOCK(vfsp);
	TAILQ_INSERT_TAIL(vfsp->mnt_opt, opt, link);
	if (!locked)
		MNT_IUNLOCK(vfsp);
}

void
vfs_clearmntopt(vfs_t *vfsp, const char *name)
{
	int locked;

	if (!(locked = mtx_owned(MNT_MTX(vfsp))))
		MNT_ILOCK(vfsp);
	vfs_deleteopt(vfsp->mnt_opt, name);
	if (!locked)
		MNT_IUNLOCK(vfsp);
}

/* Unmount the filesystem described by mp. */
static int
smbfs_unmount(struct mount *mp, int mntflags)
{
	struct thread *td;
	struct smbmount *smp = VFSTOSMBFS(mp);
	struct smb_cred *scred;
	struct smb_dev *dev;
	int error, flags;

	SMBVDEBUG("smbfs_unmount: flags=%04x\n", mntflags);
	td = curthread;
	flags = 0;
	if (mntflags & MNT_FORCE)
		flags |= FORCECLOSE;
	/*
	 * Keep trying to flush the vnode list for the mount while 
	 * some are still busy and we are making progress towards
	 * making them not busy. This is needed because smbfs vnodes
	 * reference their parent directory but may appear after their
	 * parent in the list; one pass over the vnode list is not
	 * sufficient in this case.
	 */
	do {
		smp->sm_didrele = 0;
		/* There is 1 extra root vnode reference from smbfs_mount(). */
		error = vflush(mp, 1, flags, td);
	} while (error == EBUSY && smp->sm_didrele != 0);
	if (error)
		return error;
	scred = smbfs_malloc_scred();
	smb_makescred(scred, td, td->td_ucred);
	error = smb_share_lock(smp->sm_share);
	if (error)
		goto out;
	smb_share_put(smp->sm_share, scred);
	SMB_LOCK();
	dev = smp->sm_dev;
	if (!dev)
		panic("No private data for mount point");
	sdp_trydestroy(dev);
	mp->mnt_data = NULL;
	SMB_UNLOCK();
	free(smp, M_SMBFSDATA);
	MNT_ILOCK(mp);
	mp->mnt_flag &= ~MNT_LOCAL;
	MNT_IUNLOCK(mp);
out:
	smbfs_free_scred(scred);
	return error;
}

/*
 * Mount the filesystem
 */
static int
devfs_mount(struct mount *mp)
{
	int error;
	struct devfs_mount *fmp;
	struct vnode *rvp;

	if (devfs_unr == NULL)
		devfs_unr = new_unrhdr(0, INT_MAX, NULL);

	error = 0;

	if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS))
		return (EOPNOTSUPP);

	fmp = malloc(sizeof *fmp, M_DEVFS, M_WAITOK | M_ZERO);
	fmp->dm_idx = alloc_unr(devfs_unr);
	sx_init(&fmp->dm_lock, "devfsmount");
	fmp->dm_holdcnt = 1;

	MNT_ILOCK(mp);
	mp->mnt_flag |= MNT_LOCAL;
	mp->mnt_kern_flag |= MNTK_MPSAFE | MNTK_LOOKUP_SHARED |
	    MNTK_EXTENDED_SHARED;
#ifdef MAC
	mp->mnt_flag |= MNT_MULTILABEL;
#endif
	MNT_IUNLOCK(mp);
	fmp->dm_mount = mp;
	mp->mnt_data = (void *) fmp;
	vfs_getnewfsid(mp);

	fmp->dm_rootdir = devfs_vmkdir(fmp, NULL, 0, NULL, DEVFS_ROOTINO);

	error = devfs_root(mp, LK_EXCLUSIVE, &rvp);
	if (error) {
		sx_destroy(&fmp->dm_lock);
		free_unr(devfs_unr, fmp->dm_idx);
		free(fmp, M_DEVFS);
		return (error);
	}

	VOP_UNLOCK(rvp, 0);

	vfs_mountedfrom(mp, "devfs");

	return (0);
}

afs_omount(struct mount *mp, char *path, caddr_t data, struct nameidata *ndp,
	THREAD_OR_PROC)
#endif
{
    /* ndp contains the mounted-from device.  Just ignore it.
     * we also don't care about our proc struct. */
    size_t size;

    if (mp->mnt_flag & MNT_UPDATE)
	return EINVAL;

    AFS_GLOCK();
    AFS_STATCNT(afs_mount);

    if (afs_globalVFS) {	/* Don't allow remounts. */
	AFS_GUNLOCK();
	return EBUSY;
    }

    afs_globalVFS = mp;
    mp->vfs_bsize = 8192;
    vfs_getnewfsid(mp);
#ifdef AFS_FBSD70_ENV /* XXX 70? */
    MNT_ILOCK(mp);
    mp->mnt_flag &= ~MNT_LOCAL;
    mp->mnt_kern_flag |= MNTK_MPSAFE; /* solid steel */
#endif
    mp->mnt_stat.f_iosize = 8192;

    if (path != NULL)
	copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1, &size);
    else
	bcopy("/afs", mp->mnt_stat.f_mntonname, size = 4);
    memset(mp->mnt_stat.f_mntonname + size, 0, MNAMELEN - size);
    memset(mp->mnt_stat.f_mntfromname, 0, MNAMELEN);
    strcpy(mp->mnt_stat.f_mntfromname, "AFS");
    /* null terminated string "AFS" will fit, just leave it be. */
    strcpy(mp->mnt_stat.f_fstypename, "afs");
#ifdef AFS_FBSD70_ENV
    MNT_IUNLOCK(mp);
#endif
    AFS_GUNLOCK();
    afs_statfs(mp, &mp->mnt_stat, p);

    return 0;
}

static int
udf_unmount(struct mount *mp, int mntflags)
{
	struct udf_mnt *udfmp;
	int error, flags = 0;

	udfmp = VFSTOUDFFS(mp);

	if (mntflags & MNT_FORCE)
		flags |= FORCECLOSE;

	if ((error = vflush(mp, 0, flags, curthread)))
		return (error);

	if (udfmp->im_flags & UDFMNT_KICONV && udf_iconv) {
		if (udfmp->im_d2l)
			udf_iconv->close(udfmp->im_d2l);
#if 0
		if (udfmp->im_l2d)
			udf_iconv->close(udfmp->im_l2d);
#endif
	}

	DROP_GIANT();
	g_topology_lock();
	g_vfs_close(udfmp->im_cp);
	g_topology_unlock();
	PICKUP_GIANT();
	vrele(udfmp->im_devvp);
	dev_rel(udfmp->im_dev);

	if (udfmp->s_table != NULL)
		free(udfmp->s_table, M_UDFMOUNT);

	free(udfmp, M_UDFMOUNT);

	mp->mnt_data = NULL;
	MNT_ILOCK(mp);
	mp->mnt_flag &= ~MNT_LOCAL;
	MNT_IUNLOCK(mp);

	return (0);
}

/*
 * Turns off quotas, assumes that ump->um_qflags are already checked
 * and QTF_CLOSING is set to indicate operation in progress. Fixes
 * ump->um_qflags and mp->mnt_flag after.
 */
int
quotaoff_inchange(struct thread *td, struct mount *mp, int type)
{
    struct ufsmount *ump;
    int i;
    int error;

    error = quotaoff1(td, mp, type);

    ump = VFSTOUFS(mp);
    UFS_LOCK(ump);
    ump->um_qflags[type] &= ~QTF_CLOSING;
    for (i = 0; i < MAXQUOTAS; i++)
        if (ump->um_quotas[i] != NULLVP)
            break;
    if (i == MAXQUOTAS) {
        MNT_ILOCK(mp);
        mp->mnt_flag &= ~MNT_QUOTA;
        MNT_IUNLOCK(mp);
    }
    UFS_UNLOCK(ump);
    return (error);
}

/*
 * Q_QUOTAON - set up a quota file for a particular filesystem.
 */
int
quotaon(struct thread *td, struct mount *mp, int type, void *fname)
{
    struct ufsmount *ump;
    struct vnode *vp, **vpp;
    struct vnode *mvp;
    struct dquot *dq;
    int error, flags;
    struct nameidata nd;

    error = priv_check(td, PRIV_UFS_QUOTAON);
    if (error != 0) {
        vfs_unbusy(mp);
        return (error);
    }

    if ((mp->mnt_flag & MNT_RDONLY) != 0) {
        vfs_unbusy(mp);
        return (EROFS);
    }

    ump = VFSTOUFS(mp);
    dq = NODQUOT;

    NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fname, td);
    flags = FREAD | FWRITE;
    vfs_ref(mp);
    vfs_unbusy(mp);
    error = vn_open(&nd, &flags, 0, NULL);
    if (error != 0) {
        vfs_rel(mp);
        return (error);
    }
    NDFREE(&nd, NDF_ONLY_PNBUF);
    vp = nd.ni_vp;
    error = vfs_busy(mp, MBF_NOWAIT);
    vfs_rel(mp);
    if (error == 0) {
        if (vp->v_type != VREG) {
            error = EACCES;
            vfs_unbusy(mp);
        }
    }
    if (error != 0) {
        VOP_UNLOCK(vp, 0);
        (void) vn_close(vp, FREAD|FWRITE, td->td_ucred, td);
        return (error);
    }

    UFS_LOCK(ump);
    if ((ump->um_qflags[type] & (QTF_OPENING|QTF_CLOSING)) != 0) {
        UFS_UNLOCK(ump);
        VOP_UNLOCK(vp, 0);
        (void) vn_close(vp, FREAD|FWRITE, td->td_ucred, td);
        vfs_unbusy(mp);
        return (EALREADY);
    }
    ump->um_qflags[type] |= QTF_OPENING|QTF_CLOSING;
    UFS_UNLOCK(ump);
    if ((error = dqopen(vp, ump, type)) != 0) {
        VOP_UNLOCK(vp, 0);
        UFS_LOCK(ump);
        ump->um_qflags[type] &= ~(QTF_OPENING|QTF_CLOSING);
        UFS_UNLOCK(ump);
        (void) vn_close(vp, FREAD|FWRITE, td->td_ucred, td);
        vfs_unbusy(mp);
        return (error);
    }
    VOP_UNLOCK(vp, 0);
    MNT_ILOCK(mp);
    mp->mnt_flag |= MNT_QUOTA;
    MNT_IUNLOCK(mp);

    vpp = &ump->um_quotas[type];
    if (*vpp != vp)
        quotaoff1(td, mp, type);

    /*
     * When the directory vnode containing the quota file is
     * inactivated, due to the shared lookup of the quota file
     * vput()ing the dvp, the qsyncvp() call for the containing
     * directory would try to acquire the quota lock exclusive.
     * At the same time, lookup already locked the quota vnode
     * shared.  Mark the quota vnode lock as allowing recursion
     * and automatically converting shared locks to exclusive.
     *
     * Also mark quota vnode as system.
     */
    vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
    vp->v_vflag |= VV_SYSTEM;
    VN_LOCK_AREC(vp);
    VN_LOCK_DSHARE(vp);
    VOP_UNLOCK(vp, 0);
    *vpp = vp;
    /*
     * Save the credential of the process that turned on quotas.
     * Set up the time limits for this quota.
//.........这里部分代码省略.........

/*
 * Build hash lists of net addresses and hang them off the mount point.
 * Called by vfs_export() to set up the lists of export addresses.
 */
static int
vfs_hang_addrlist(struct mount *mp, struct netexport *nep,
    struct export_args *argp)
{
	register struct netcred *np;
	register struct radix_node_head *rnh;
	register int i;
	struct radix_node *rn;
	struct sockaddr *saddr, *smask = 0;
	struct domain *dom;
	int error;

	/*
	 * XXX: This routine converts from a `struct xucred'
	 * (argp->ex_anon) to a `struct ucred' (np->netc_anon).  This
	 * operation is questionable; for example, what should be done
	 * with fields like cr_uidinfo and cr_prison?  Currently, this
	 * routine does not touch them (leaves them as NULL).
	 */
	if (argp->ex_anon.cr_version != XUCRED_VERSION) {
		vfs_mount_error(mp, "ex_anon.cr_version: %d != %d",
		    argp->ex_anon.cr_version, XUCRED_VERSION);
		return (EINVAL);
	}

	if (argp->ex_addrlen == 0) {
		if (mp->mnt_flag & MNT_DEFEXPORTED) {
			vfs_mount_error(mp,
			    "MNT_DEFEXPORTED already set for mount %p", mp);
			return (EPERM);
		}
		np = &nep->ne_defexported;
		np->netc_exflags = argp->ex_flags;
		np->netc_anon = crget();
		np->netc_anon->cr_uid = argp->ex_anon.cr_uid;
		crsetgroups(np->netc_anon, argp->ex_anon.cr_ngroups,
		    argp->ex_anon.cr_groups);
		np->netc_anon->cr_prison = &prison0;
		prison_hold(np->netc_anon->cr_prison);
		np->netc_numsecflavors = argp->ex_numsecflavors;
		bcopy(argp->ex_secflavors, np->netc_secflavors,
		    sizeof(np->netc_secflavors));
		MNT_ILOCK(mp);
		mp->mnt_flag |= MNT_DEFEXPORTED;
		MNT_IUNLOCK(mp);
		return (0);
	}

#if MSIZE <= 256
	if (argp->ex_addrlen > MLEN) {
		vfs_mount_error(mp, "ex_addrlen %d is greater than %d",
		    argp->ex_addrlen, MLEN);
		return (EINVAL);
	}
#endif

	i = sizeof(struct netcred) + argp->ex_addrlen + argp->ex_masklen;
	np = (struct netcred *) malloc(i, M_NETADDR, M_WAITOK | M_ZERO);
	saddr = (struct sockaddr *) (np + 1);
	if ((error = copyin(argp->ex_addr, saddr, argp->ex_addrlen)))
		goto out;
	if (saddr->sa_family == AF_UNSPEC || saddr->sa_family > AF_MAX) {
		error = EINVAL;
		vfs_mount_error(mp, "Invalid saddr->sa_family: %d");
		goto out;
	}
	if (saddr->sa_len > argp->ex_addrlen)
		saddr->sa_len = argp->ex_addrlen;
	if (argp->ex_masklen) {
		smask = (struct sockaddr *)((caddr_t)saddr + argp->ex_addrlen);
		error = copyin(argp->ex_mask, smask, argp->ex_masklen);
		if (error)
			goto out;
		if (smask->sa_len > argp->ex_masklen)
			smask->sa_len = argp->ex_masklen;
	}
	i = saddr->sa_family;
	if ((rnh = nep->ne_rtable[i]) == NULL) {
		/*
		 * Seems silly to initialize every AF when most are not used,
		 * do so on demand here
		 */
		for (dom = domains; dom; dom = dom->dom_next) {
			KASSERT(((i == AF_INET) || (i == AF_INET6)), 
			    ("unexpected protocol in vfs_hang_addrlist"));
			if (dom->dom_family == i && dom->dom_rtattach) {
				/*
				 * XXX MRT 
				 * The INET and INET6 domains know the
				 * offset already. We don't need to send it
				 * So we just use it as a flag to say that
				 * we are or are not setting up a real routing
				 * table. Only IP and IPV6 need have this
				 * be 0 so all other protocols can stay the 
				 * same (ABI compatible).
				 */ 
//.........这里部分代码省略.........

static int
udf_mountfs(struct vnode *devvp, struct mount *mp)
{
	struct buf *bp = NULL;
	struct cdev *dev;
	struct anchor_vdp avdp;
	struct udf_mnt *udfmp = NULL;
	struct part_desc *pd;
	struct logvol_desc *lvd;
	struct fileset_desc *fsd;
	struct file_entry *root_fentry;
	uint32_t sector, size, mvds_start, mvds_end;
	uint32_t logical_secsize;
	uint32_t fsd_offset = 0;
	uint16_t part_num = 0, fsd_part = 0;
	int error = EINVAL;
	int logvol_found = 0, part_found = 0, fsd_found = 0;
	int bsize;
	struct g_consumer *cp;
	struct bufobj *bo;

	dev = devvp->v_rdev;
	dev_ref(dev);
	DROP_GIANT();
	g_topology_lock();
	error = g_vfs_open(devvp, &cp, "udf", 0);
	g_topology_unlock();
	PICKUP_GIANT();
	VOP_UNLOCK(devvp, 0);
	if (error)
		goto bail;

	bo = &devvp->v_bufobj;

	if (devvp->v_rdev->si_iosize_max != 0)
		mp->mnt_iosize_max = devvp->v_rdev->si_iosize_max;
	if (mp->mnt_iosize_max > MAXPHYS)
		mp->mnt_iosize_max = MAXPHYS;

	/* XXX: should be M_WAITOK */
	udfmp = malloc(sizeof(struct udf_mnt), M_UDFMOUNT,
	    M_NOWAIT | M_ZERO);
	if (udfmp == NULL) {
		printf("Cannot allocate UDF mount struct\n");
		error = ENOMEM;
		goto bail;
	}

	mp->mnt_data = udfmp;
	mp->mnt_stat.f_fsid.val[0] = dev2udev(devvp->v_rdev);
	mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
	MNT_ILOCK(mp);
	mp->mnt_flag |= MNT_LOCAL;
	mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED;
	MNT_IUNLOCK(mp);
	udfmp->im_mountp = mp;
	udfmp->im_dev = dev;
	udfmp->im_devvp = devvp;
	udfmp->im_d2l = NULL;
	udfmp->im_cp = cp;
	udfmp->im_bo = bo;

#if 0
	udfmp->im_l2d = NULL;
#endif
	/*
	 * The UDF specification defines a logical sectorsize of 2048
	 * for DVD media.
	 */
	logical_secsize = 2048;

	if (((logical_secsize % cp->provider->sectorsize) != 0) ||
	    (logical_secsize < cp->provider->sectorsize)) {
		error = EINVAL;
		goto bail;
	}

	bsize = cp->provider->sectorsize;

	/* 
	 * Get the Anchor Volume Descriptor Pointer from sector 256.
	 * XXX Should also check sector n - 256, n, and 512.
	 */
	sector = 256;
	if ((error = bread(devvp, sector * btodb(logical_secsize), bsize,
			   NOCRED, &bp)) != 0)
		goto bail;
	if ((error = udf_checktag((struct desc_tag *)bp->b_data, TAGID_ANCHOR)))
		goto bail;

	bcopy(bp->b_data, &avdp, sizeof(struct anchor_vdp));
	brelse(bp);
	bp = NULL;

	/*
	 * Extract the Partition Descriptor and Logical Volume Descriptor
	 * from the Volume Descriptor Sequence.
	 * XXX Should we care about the partition type right now?
	 * XXX What about multiple partitions?
	 */
//.........这里部分代码省略.........

//.........这里部分代码省略.........
		 */
		if (args.sotype == SOCK_DGRAM && nmp->nm_sotype == SOCK_STREAM)
			tprintf(curthread->td_proc, LOG_WARNING,
	"Warning: mount -u that changes TCP->UDP can result in hung threads\n");

		/*
		 * When doing an update, we can't change from or to
		 * v3, switch lockd strategies or change cookie translation
		 */
		args.flags = (args.flags &
		    ~(NFSMNT_NFSV3 | NFSMNT_NOLOCKD /*|NFSMNT_XLATECOOKIE*/)) |
		    (nmp->nm_flag &
			(NFSMNT_NFSV3 | NFSMNT_NOLOCKD /*|NFSMNT_XLATECOOKIE*/));
		nfs_decode_args(mp, nmp, &args, NULL);
		goto out;
	}

	/*
	 * Make the nfs_ip_paranoia sysctl serve as the default connection
	 * or no-connection mode for those protocols that support 
	 * no-connection mode (the flag will be cleared later for protocols
	 * that do not support no-connection mode).  This will allow a client
	 * to receive replies from a different IP then the request was
	 * sent to.  Note: default value for nfs_ip_paranoia is 1 (paranoid),
	 * not 0.
	 */
	if (nfs_ip_paranoia == 0)
		args.flags |= NFSMNT_NOCONN;

	if (has_nfs_args_opt) {
		/*
		 * In the 'nfs_args' case, the pointers in the args
		 * structure are in userland - we copy them in here.
		 */
		if (!has_fh_opt) {
			error = copyin((caddr_t)args.fh, (caddr_t)nfh,
			    args.fhsize);
			if (error) {
				goto out;
			}
			args.fh = nfh;
		}
		if (!has_hostname_opt) {
			error = copyinstr(args.hostname, hst, MNAMELEN-1, &len);
			if (error) {
				goto out;
			}
			bzero(&hst[len], MNAMELEN - len);
			args.hostname = hst;
		}
		if (!has_addr_opt) {
			/* sockargs() call must be after above copyin() calls */
			error = getsockaddr(&nam, (caddr_t)args.addr,
			    args.addrlen);
			if (error) {
				goto out;
			}
		}
	} else if (has_addr_opt == 0) {
		vfs_mount_error(mp, "No server address");
		error = EINVAL;
		goto out;
	}
	error = mountnfs(&args, mp, nam, args.hostname, &vp,
	    curthread->td_ucred, nametimeo, negnametimeo);
out:
	if (!error) {
		MNT_ILOCK(mp);
		mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED;
		MNT_IUNLOCK(mp);
	}
	return (error);
}


/*
 * VFS Operations.
 *
 * mount system call
 * It seems a bit dumb to copyinstr() the host and path here and then
 * bcopy() them in mountnfs(), but I wanted to detect errors before
 * doing the sockargs() call because sockargs() allocates an mbuf and
 * an error after that means that I have to release the mbuf.
 */
/* ARGSUSED */
static int
nfs_cmount(struct mntarg *ma, void *data, uint64_t flags)
{
	int error;
	struct nfs_args args;

	error = copyin(data, &args, sizeof (struct nfs_args));
	if (error)
		return error;

	ma = mount_arg(ma, "nfs_args", &args, sizeof args);

	error = kernel_mount(ma, flags);
	return (error);
}

/*
 * Unmount the filesystem described by mp.
 */
static int
msdosfs_unmount(struct mount *mp, int mntflags)
{
	struct msdosfsmount *pmp;
	int error, flags;

	error = flags = 0;
	pmp = VFSTOMSDOSFS(mp);
	if ((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0)
		error = msdosfs_sync(mp, MNT_WAIT);
	if ((mntflags & MNT_FORCE) != 0)
		flags |= FORCECLOSE;
	else if (error != 0)
		return (error);
	error = vflush(mp, 0, flags, curthread);
	if (error != 0 && error != ENXIO)
		return (error);
	if ((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0) {
		error = markvoldirty(pmp, 0);
		if (error && error != ENXIO) {
			(void)markvoldirty(pmp, 1);
			return (error);
		}
	}
	if (pmp->pm_flags & MSDOSFSMNT_KICONV && msdosfs_iconv) {
		if (pmp->pm_w2u)
			msdosfs_iconv->close(pmp->pm_w2u);
		if (pmp->pm_u2w)
			msdosfs_iconv->close(pmp->pm_u2w);
		if (pmp->pm_d2u)
			msdosfs_iconv->close(pmp->pm_d2u);
		if (pmp->pm_u2d)
			msdosfs_iconv->close(pmp->pm_u2d);
	}

#ifdef MSDOSFS_DEBUG
	{
		struct vnode *vp = pmp->pm_devvp;
		struct bufobj *bo;

		bo = &vp->v_bufobj;
		BO_LOCK(bo);
		VI_LOCK(vp);
		vn_printf(vp,
		    "msdosfs_umount(): just before calling VOP_CLOSE()\n");
		printf("freef %p, freeb %p, mount %p\n",
		    TAILQ_NEXT(vp, v_actfreelist), vp->v_actfreelist.tqe_prev,
		    vp->v_mount);
		printf("cleanblkhd %p, dirtyblkhd %p, numoutput %ld, type %d\n",
		    TAILQ_FIRST(&vp->v_bufobj.bo_clean.bv_hd),
		    TAILQ_FIRST(&vp->v_bufobj.bo_dirty.bv_hd),
		    vp->v_bufobj.bo_numoutput, vp->v_type);
		VI_UNLOCK(vp);
		BO_UNLOCK(bo);
	}
#endif
	DROP_GIANT();
	if (pmp->pm_devvp->v_type == VCHR && pmp->pm_devvp->v_rdev != NULL)
		pmp->pm_devvp->v_rdev->si_mountpt = NULL;
	g_topology_lock();
	g_vfs_close(pmp->pm_cp);
	g_topology_unlock();
	PICKUP_GIANT();
	vrele(pmp->pm_devvp);
	dev_rel(pmp->pm_dev);
	free(pmp->pm_inusemap, M_MSDOSFSFAT);
	if (pmp->pm_flags & MSDOSFS_LARGEFS)
		msdosfs_fileno_free(mp);
	lockdestroy(&pmp->pm_fatlock);
	free(pmp, M_MSDOSFSMNT);
	mp->mnt_data = NULL;
	MNT_ILOCK(mp);
	mp->mnt_flag &= ~MNT_LOCAL;
	MNT_IUNLOCK(mp);
	return (error);
}

static int
udf_mount(struct mount *mp)
{
	struct vnode *devvp;	/* vnode of the mount device */
	struct thread *td;
	struct udf_mnt *imp = NULL;
	struct vfsoptlist *opts;
	char *fspec, *cs_disk, *cs_local;
	int error, len, *udf_flags;
	struct nameidata nd, *ndp = &nd;

	td = curthread;
	opts = mp->mnt_optnew;

	/*
	 * Unconditionally mount as read-only.
	 */
	MNT_ILOCK(mp);
	mp->mnt_flag |= MNT_RDONLY;
	MNT_IUNLOCK(mp);

	/*
	 * No root filesystem support.  Probably not a big deal, since the
	 * bootloader doesn't understand UDF.
	 */
	if (mp->mnt_flag & MNT_ROOTFS)
		return (ENOTSUP);

	fspec = NULL;
	error = vfs_getopt(opts, "from", (void **)&fspec, &len);
	if (!error && fspec[len - 1] != '\0')
		return (EINVAL);

	if (mp->mnt_flag & MNT_UPDATE) {
		return (0);
	}

	/* Check that the mount device exists */
	if (fspec == NULL)
		return (EINVAL);
	NDINIT(ndp, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, fspec, td);
	if ((error = namei(ndp)))
		return (error);
	NDFREE(ndp, NDF_ONLY_PNBUF);
	devvp = ndp->ni_vp;

	if (vn_isdisk(devvp, &error) == 0) {
		vput(devvp);
		return (error);
	}

	/* Check the access rights on the mount device */
	error = VOP_ACCESS(devvp, VREAD, td->td_ucred, td);
	if (error)
		error = priv_check(td, PRIV_VFS_MOUNT_PERM);
	if (error) {
		vput(devvp);
		return (error);
	}

	if ((error = udf_mountfs(devvp, mp))) {
		vrele(devvp);
		return (error);
	}

	imp = VFSTOUDFFS(mp);

	udf_flags = NULL;
	error = vfs_getopt(opts, "flags", (void **)&udf_flags, &len);
	if (error || len != sizeof(int))
		return (EINVAL);
	imp->im_flags = *udf_flags;

	if (imp->im_flags & UDFMNT_KICONV && udf_iconv) {
		cs_disk = NULL;
		error = vfs_getopt(opts, "cs_disk", (void **)&cs_disk, &len);
		if (!error && cs_disk[len - 1] != '\0')
			return (EINVAL);
		cs_local = NULL;
		error = vfs_getopt(opts, "cs_local", (void **)&cs_local, &len);
		if (!error && cs_local[len - 1] != '\0')
			return (EINVAL);
		udf_iconv->open(cs_local, cs_disk, &imp->im_d2l);
#if 0
		udf_iconv->open(cs_disk, cs_local, &imp->im_l2d);
#endif
	}

	vfs_mountedfrom(mp, fspec);
	return 0;
};

/*
 * mp - path - addr in user space of mount point (ie /usr or whatever)
 * data - addr in user space of mount params including the name of the block
 * special file to treat as a filesystem.
 */
static int
msdosfs_mount(struct mount *mp)
{
	struct vnode *devvp;	  /* vnode for blk device to mount */
	struct thread *td;
	/* msdosfs specific mount control block */
	struct msdosfsmount *pmp = NULL;
	struct nameidata ndp;
	int error, flags;
	accmode_t accmode;
	char *from;

	td = curthread;
	if (vfs_filteropt(mp->mnt_optnew, msdosfs_opts))
		return (EINVAL);

	/*
	 * If updating, check whether changing from read-only to
	 * read/write; if there is no device name, that's all we do.
	 */
	if (mp->mnt_flag & MNT_UPDATE) {
		pmp = VFSTOMSDOSFS(mp);
		if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0)) {
			/*
			 * Forbid export requests if filesystem has
			 * MSDOSFS_LARGEFS flag set.
			 */
			if ((pmp->pm_flags & MSDOSFS_LARGEFS) != 0) {
				vfs_mount_error(mp,
				    "MSDOSFS_LARGEFS flag set, cannot export");
				return (EOPNOTSUPP);
			}
		}
		if (!(pmp->pm_flags & MSDOSFSMNT_RONLY) &&
		    vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0)) {
			error = VFS_SYNC(mp, MNT_WAIT);
			if (error)
				return (error);
			flags = WRITECLOSE;
			if (mp->mnt_flag & MNT_FORCE)
				flags |= FORCECLOSE;
			error = vflush(mp, 0, flags, td);
			if (error)
				return (error);

			/*
			 * Now the volume is clean.  Mark it so while the
			 * device is still rw.
			 */
			error = markvoldirty(pmp, 0);
			if (error) {
				(void)markvoldirty(pmp, 1);
				return (error);
			}

			/* Downgrade the device from rw to ro. */
			DROP_GIANT();
			g_topology_lock();
			error = g_access(pmp->pm_cp, 0, -1, 0);
			g_topology_unlock();
			PICKUP_GIANT();
			if (error) {
				(void)markvoldirty(pmp, 1);
				return (error);
			}

			/*
			 * Backing out after an error was painful in the
			 * above.  Now we are committed to succeeding.
			 */
			pmp->pm_fmod = 0;
			pmp->pm_flags |= MSDOSFSMNT_RONLY;
			MNT_ILOCK(mp);
			mp->mnt_flag |= MNT_RDONLY;
			MNT_IUNLOCK(mp);
		} else if ((pmp->pm_flags & MSDOSFSMNT_RONLY) &&
		    !vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0)) {
			/*
			 * If upgrade to read-write by non-root, then verify
			 * that user has necessary permissions on the device.
			 */
			devvp = pmp->pm_devvp;
			vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
			error = VOP_ACCESS(devvp, VREAD | VWRITE,
			    td->td_ucred, td);
			if (error)
				error = priv_check(td, PRIV_VFS_MOUNT_PERM);
			if (error) {
				VOP_UNLOCK(devvp, 0);
				return (error);
			}
			VOP_UNLOCK(devvp, 0);
			DROP_GIANT();
			g_topology_lock();
			error = g_access(pmp->pm_cp, 0, 1, 0);
//.........这里部分代码省略.........

//.........这里部分代码省略.........
		fp = (struct fsinfo *)bp->b_data;
		if (!bcmp(fp->fsisig1, "RRaA", 4)
		    && !bcmp(fp->fsisig2, "rrAa", 4)
		    && !bcmp(fp->fsisig3, "\0\0\125\252", 4)) {
			pmp->pm_nxtfree = getulong(fp->fsinxtfree);
			if (pmp->pm_nxtfree > pmp->pm_maxcluster)
				pmp->pm_nxtfree = CLUST_FIRST;
		} else
			pmp->pm_fsinfo = 0;
		brelse(bp);
		bp = NULL;
	}

	/*
	 * Finish initializing pmp->pm_nxtfree (just in case the first few
	 * sectors aren't properly reserved in the FAT).  This completes
	 * the fixup for fp->fsinxtfree, and fixes up the zero-initialized
	 * value if there is no fsinfo.  We will use pmp->pm_nxtfree
	 * internally even if there is no fsinfo.
	 */
	if (pmp->pm_nxtfree < CLUST_FIRST)
		pmp->pm_nxtfree = CLUST_FIRST;

	/*
	 * Allocate memory for the bitmap of allocated clusters, and then
	 * fill it in.
	 */
	pmp->pm_inusemap = malloc(howmany(pmp->pm_maxcluster + 1, N_INUSEBITS)
				  * sizeof(*pmp->pm_inusemap),
				  M_MSDOSFSFAT, M_WAITOK);

	/*
	 * fillinusemap() needs pm_devvp.
	 */
	pmp->pm_devvp = devvp;
	pmp->pm_dev = dev;

	/*
	 * Have the inuse map filled in.
	 */
	MSDOSFS_LOCK_MP(pmp);
	error = fillinusemap(pmp);
	MSDOSFS_UNLOCK_MP(pmp);
	if (error != 0)
		goto error_exit;

	/*
	 * If they want fat updates to be synchronous then let them suffer
	 * the performance degradation in exchange for the on disk copy of
	 * the fat being correct just about all the time.  I suppose this
	 * would be a good thing to turn on if the kernel is still flakey.
	 */
	if (mp->mnt_flag & MNT_SYNCHRONOUS)
		pmp->pm_flags |= MSDOSFSMNT_WAITONFAT;

	/*
	 * Finish up.
	 */
	if (ronly)
		pmp->pm_flags |= MSDOSFSMNT_RONLY;
	else {
		if ((error = markvoldirty(pmp, 1)) != 0) {
			(void)markvoldirty(pmp, 0);
			goto error_exit;
		}
		pmp->pm_fmod = 1;
	}
	mp->mnt_data =  pmp;
	mp->mnt_stat.f_fsid.val[0] = dev2udev(dev);
	mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
	MNT_ILOCK(mp);
	mp->mnt_flag |= MNT_LOCAL;
	mp->mnt_kern_flag |= MNTK_USES_BCACHE;
	MNT_IUNLOCK(mp);

	if (pmp->pm_flags & MSDOSFS_LARGEFS)
		msdosfs_fileno_init(mp);

	return 0;

error_exit:
	if (bp)
		brelse(bp);
	if (cp != NULL) {
		DROP_GIANT();
		g_topology_lock();
		g_vfs_close(cp);
		g_topology_unlock();
		PICKUP_GIANT();
	}
	if (pmp) {
		lockdestroy(&pmp->pm_fatlock);
		if (pmp->pm_inusemap)
			free(pmp->pm_inusemap, M_MSDOSFSFAT);
		free(pmp, M_MSDOSFSMNT);
		mp->mnt_data = NULL;
	}
	dev_rel(dev);
	return (error);
}

static int
ntfs_mount(struct mount *mp)
{
	int err = 0, error;
	struct vnode *devvp;
	struct nameidata ndp;
	struct thread *td;
	char *from;

	td = curthread;
	if (vfs_filteropt(mp->mnt_optnew, ntfs_opts))
		return (EINVAL);

	/* Force mount as read-only. */
	MNT_ILOCK(mp);
	mp->mnt_flag |= MNT_RDONLY;
	MNT_IUNLOCK(mp);

	from = vfs_getopts(mp->mnt_optnew, "from", &error);
	if (error)	
		return (error);

	/*
	 * If updating, check whether changing from read-only to
	 * read/write.
	 */
	if (mp->mnt_flag & MNT_UPDATE) {
		if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0)) {
			/* Process export requests in vfs_mount.c */
			return (0);
		} else {
			printf("ntfs_mount(): MNT_UPDATE not supported\n");
			return (EINVAL);
		}
	}

	/*
	 * Not an update, or updating the name: look up the name
	 * and verify that it refers to a sensible block device.
	 */
	NDINIT(&ndp, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, from, td);
	err = namei(&ndp);
	if (err)
		return (err);
	NDFREE(&ndp, NDF_ONLY_PNBUF);
	devvp = ndp.ni_vp;

	if (!vn_isdisk(devvp, &err))  {
		vput(devvp);
		return (err);
	}

	/*
	 * If mount by non-root, then verify that user has necessary
	 * permissions on the device.
	 */
	err = VOP_ACCESS(devvp, VREAD, td->td_ucred, td);
	if (err)
		err = priv_check(td, PRIV_VFS_MOUNT_PERM);
	if (err) {
		vput(devvp);
		return (err);
	}


	/*
	 * Since this is a new mount, we want the names for the device and
	 * the mount point copied in.  If an error occurs, the mountpoint is
	 * discarded by the upper level code.  Note that vfs_mount() handles
	 * copying the mountpoint f_mntonname for us, so we don't have to do
	 * it here unless we want to set it to something other than "path"
	 * for some rason.
	 */

	err = ntfs_mountfs(devvp, mp, td);
	if (err == 0) {

		/* Save "mounted from" info for mount point. */
		vfs_mountedfrom(mp, from);
	} else
		vrele(devvp);
	return (err);
}

//.........这里部分代码省略.........
		isvnunlocked = 1;
	}
	/*
	 * Find lower node
	 */
	NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target, curthread);
	error = namei(ndp);

	/*
	 * Re-lock vnode.
	 * XXXKIB This is deadlock-prone as well.
	 */
	if (isvnunlocked)
		vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY);

	if (error)
		return (error);
	NDFREE(ndp, NDF_ONLY_PNBUF);

	/*
	 * Sanity check on lower vnode
	 */
	lowerrootvp = ndp->ni_vp;

	/*
	 * Check multi null mount to avoid `lock against myself' panic.
	 */
	if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) {
		NULLFSDEBUG("nullfs_mount: multi null mount?\n");
		vput(lowerrootvp);
		return (EDEADLK);
	}

	xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
	    M_NULLFSMNT, M_WAITOK | M_ZERO);

	/*
	 * Save reference to underlying FS
	 */
	xmp->nullm_vfs = lowerrootvp->v_mount;

	/*
	 * Save reference.  Each mount also holds
	 * a reference on the root vnode.
	 */
	error = null_nodeget(mp, lowerrootvp, &vp);
	/*
	 * Make sure the node alias worked
	 */
	if (error) {
		free(xmp, M_NULLFSMNT);
		return (error);
	}

	/*
	 * Keep a held reference to the root vnode.
	 * It is vrele'd in nullfs_unmount.
	 */
	nullm_rootvp = vp;
	nullm_rootvp->v_vflag |= VV_ROOT;
	xmp->nullm_rootvp = nullm_rootvp;

	/*
	 * Unlock the node (either the lower or the alias)
	 */
	VOP_UNLOCK(vp, 0);

	if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) {
		MNT_ILOCK(mp);
		mp->mnt_flag |= MNT_LOCAL;
		MNT_IUNLOCK(mp);
	}

	xmp->nullm_flags |= NULLM_CACHE;
	if (vfs_getopt(mp->mnt_optnew, "nocache", NULL, NULL) == 0)
		xmp->nullm_flags &= ~NULLM_CACHE;

	MNT_ILOCK(mp);
	if ((xmp->nullm_flags & NULLM_CACHE) != 0) {
		mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag &
		    (MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED |
		    MNTK_EXTENDED_SHARED);
	}
	mp->mnt_kern_flag |= MNTK_LOOKUP_EXCL_DOTDOT;
	MNT_IUNLOCK(mp);
	mp->mnt_data = xmp;
	vfs_getnewfsid(mp);
	if ((xmp->nullm_flags & NULLM_CACHE) != 0) {
		MNT_ILOCK(xmp->nullm_vfs);
		TAILQ_INSERT_TAIL(&xmp->nullm_vfs->mnt_uppers, mp,
		    mnt_upper_link);
		MNT_IUNLOCK(xmp->nullm_vfs);
	}

	vfs_mountedfrom(mp, target);

	NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n",
		mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
	return (0);
}

/*
 * High level function to manipulate export options on a mount point
 * and the passed in netexport.
 * Struct export_args *argp is the variable used to twiddle options,
 * the structure is described in sys/mount.h
 */
int
vfs_export(struct mount *mp, struct export_args *argp)
{
	struct netexport *nep;
	int error;

	if (argp->ex_numsecflavors < 0
	    || argp->ex_numsecflavors >= MAXSECFLAVORS)
		return (EINVAL);

	error = 0;
	lockmgr(&mp->mnt_explock, LK_EXCLUSIVE, NULL);
	nep = mp->mnt_export;
	if (argp->ex_flags & MNT_DELEXPORT) {
		if (nep == NULL) {
			error = ENOENT;
			goto out;
		}
		if (mp->mnt_flag & MNT_EXPUBLIC) {
			vfs_setpublicfs(NULL, NULL, NULL);
			MNT_ILOCK(mp);
			mp->mnt_flag &= ~MNT_EXPUBLIC;
			MNT_IUNLOCK(mp);
		}
		vfs_free_addrlist(nep);
		mp->mnt_export = NULL;
		free(nep, M_MOUNT);
		nep = NULL;
		MNT_ILOCK(mp);
		mp->mnt_flag &= ~(MNT_EXPORTED | MNT_DEFEXPORTED);
		MNT_IUNLOCK(mp);
	}
	if (argp->ex_flags & MNT_EXPORTED) {
		if (nep == NULL) {
			nep = malloc(sizeof(struct netexport), M_MOUNT, M_WAITOK | M_ZERO);
			mp->mnt_export = nep;
		}
		if (argp->ex_flags & MNT_EXPUBLIC) {
			if ((error = vfs_setpublicfs(mp, nep, argp)) != 0)
				goto out;
			MNT_ILOCK(mp);
			mp->mnt_flag |= MNT_EXPUBLIC;
			MNT_IUNLOCK(mp);
		}
		if ((error = vfs_hang_addrlist(mp, nep, argp)))
			goto out;
		MNT_ILOCK(mp);
		mp->mnt_flag |= MNT_EXPORTED;
		MNT_IUNLOCK(mp);
	}

out:
	lockmgr(&mp->mnt_explock, LK_RELEASE, NULL);
	/*
	 * Once we have executed the vfs_export() command, we do
	 * not want to keep the "export" option around in the
	 * options list, since that will cause subsequent MNT_UPDATE
	 * calls to fail.  The export information is saved in
	 * mp->mnt_export, so we can safely delete the "export" mount option
	 * here.
	 */
	vfs_deleteopt(mp->mnt_optnew, "export");
	vfs_deleteopt(mp->mnt_opt, "export");
	return (error);
}