Unleashed v1.4

[unleashed.git] / kernel / fs / autofs / auto_subr.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 1992, 2010, Oracle and/or its affiliates. All rights reserved.
 */

#include <sys/param.h>
#include <sys/kmem.h>
#include <sys/errno.h>
#include <sys/proc.h>
#include <sys/disp.h>
#include <sys/vfs.h>
#include <sys/vnode.h>
#include <sys/pathname.h>
#include <sys/cred.h>
#include <sys/mount.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <sys/systm.h>
#include <sys/dirent.h>
#include <sys/fs_subr.h>
#include <sys/fs/autofs.h>
#include <sys/callb.h>
#include <sys/sysmacros.h>
#include <sys/zone.h>
#include <sys/door.h>
#include <sys/fs/mntdata.h>
#include <nfs/mount.h>
#include <rpc/clnt.h>
#include <rpcsvc/autofs_prot.h>
#include <nfs/rnode.h>
#include <sys/utsname.h>
#include <sys/schedctl.h>

/*
 * Autofs and Zones:
 *
 * Zones are delegated the responsibility of managing their own autofs mounts
 * and maps.  Each zone runs its own copy of automountd, with its own timeouts,
 * and other logically "global" parameters.  kRPC and virtualization in the
 * loopback transport (tl) will prevent a zone from communicating with another
 * zone's automountd.
 *
 * Each zone has its own "rootfnnode" and associated tree of auto nodes.
 *
 * Each zone also has its own set of "unmounter" kernel threads; these are
 * created and run within the zone's context (ie, they are created via
 * zthread_create()).
 *
 * Cross-zone mount triggers are disallowed.  There is a check in
 * auto_trigger_mount() to this effect; EPERM is returned to indicate that the
 * mount is not owned by the caller.
 *
 * autofssys() enables a caller in the global zone to clean up in-kernel (as
 * well as regular) autofs mounts via the unmount_tree() mechanism.  This is
 * routinely done when all mounts are removed as part of zone shutdown.
 */
#define TYPICALMAXPATHLEN       64

static kmutex_t autofs_nodeid_lock;

/* max number of unmount threads running */
static int autofs_unmount_threads = 5;
static int autofs_unmount_thread_timer = 120;   /* in seconds */

static int auto_perform_link(fnnode_t *, struct linka *, cred_t *);
static int auto_perform_actions(fninfo_t *, fnnode_t *,
    action_list *, cred_t *);
static int auto_getmntpnt(vnode_t *, char *, vnode_t **, cred_t *);
static int auto_lookup_request(fninfo_t *, char *, struct linka *,
    bool_t, bool_t *, cred_t *);
static int auto_mount_request(fninfo_t *, char *, action_list **, cred_t *,
    bool_t);

/*
 * Clears the MF_INPROG flag, and wakes up those threads sleeping on
 * fn_cv_mount if MF_WAITING is set.
 */
void
auto_unblock_others(
        fnnode_t *fnp,
        uint_t operation)               /* either MF_INPROG or MF_LOOKUP */
{
        ASSERT(operation & (MF_INPROG | MF_LOOKUP));
        fnp->fn_flags &= ~operation;
        if (fnp->fn_flags & MF_WAITING) {
                fnp->fn_flags &= ~MF_WAITING;
                cv_broadcast(&fnp->fn_cv_mount);
        }
}

int
auto_wait4mount(fnnode_t *fnp)
{
        int error;
        k_sigset_t smask;

        AUTOFS_DPRINT((4, "auto_wait4mount: fnp=%p\n", (void *)fnp));

        mutex_enter(&fnp->fn_lock);
        while (fnp->fn_flags & (MF_INPROG | MF_LOOKUP)) {
                /*
                 * There is a mount or a lookup in progress.
                 */
                fnp->fn_flags |= MF_WAITING;
                sigintr(&smask, 1);
                if (!cv_wait_sig(&fnp->fn_cv_mount, &fnp->fn_lock)) {
                        /*
                         * Decided not to wait for operation to
                         * finish after all.
                         */
                        sigunintr(&smask);
                        mutex_exit(&fnp->fn_lock);
                        return (EINTR);
                }
                sigunintr(&smask);
        }
        error = fnp->fn_error;

        if (error == EINTR) {
                /*
                 * The thread doing the mount got interrupted, we need to
                 * try again, by returning EAGAIN.
                 */
                error = EAGAIN;
        }
        mutex_exit(&fnp->fn_lock);

        AUTOFS_DPRINT((5, "auto_wait4mount: fnp=%p error=%d\n", (void *)fnp,
            error));
        return (error);
}

int
auto_lookup_aux(fnnode_t *fnp, char *name, cred_t *cred)
{
        struct fninfo *fnip;
        struct linka link;
        bool_t mountreq = FALSE;
        int error = 0;

        fnip = vfstofni(fntovn(fnp)->v_vfsp);
        bzero(&link, sizeof (link));
        error = auto_lookup_request(fnip, name, &link, TRUE, &mountreq, cred);
        if (!error) {
                if (link.link != NULL) {
                        error = ENOENT;
                        /*
                         * This node should be a symlink
                         */
                        if (*link.link != '\0')
                                error = auto_perform_link(fnp, &link, cred);
                } else if (mountreq) {
                        /*
                         * The automount daemon is requesting a mount,
                         * implying this entry must be a wildcard match and
                         * therefore in need of verification that the entry
                         * exists on the server.
                         */
                        mutex_enter(&fnp->fn_lock);
                        AUTOFS_BLOCK_OTHERS(fnp, MF_INPROG);
                        fnp->fn_error = 0;

                        /*
                         * Unblock other lookup requests on this node,
                         * this is needed to let the lookup generated by
                         * the mount call to complete. The caveat is
                         * other lookups on this node can also get by,
                         * i.e., another lookup on this node that occurs
                         * while this lookup is attempting the mount
                         * would return a positive result no matter what.
                         * Therefore two lookups on the this node could
                         * potentially get disparate results.
                         */
                        AUTOFS_UNBLOCK_OTHERS(fnp, MF_LOOKUP);
                        mutex_exit(&fnp->fn_lock);
                        /*
                         * auto_new_mount_thread fires up a new thread which
                         * calls automountd finishing up the work
                         */
                        auto_new_mount_thread(fnp, name, cred);

                        /*
                         * At this point, we are simply another thread
                         * waiting for the mount to complete
                         */
                        error = auto_wait4mount(fnp);
                        if (error == AUTOFS_SHUTDOWN)
                                error = ENOENT;
                }
        }

        if (link.link)
                kmem_free(link.link, strlen(link.link) + 1);
        if (link.dir)
                kmem_free(link.dir, strlen(link.dir) + 1);
        mutex_enter(&fnp->fn_lock);
        fnp->fn_error = error;

        /*
         * Notify threads waiting for lookup/mount that
         * it's done.
         */
        if (mountreq) {
                AUTOFS_UNBLOCK_OTHERS(fnp, MF_INPROG);
        } else {
                AUTOFS_UNBLOCK_OTHERS(fnp, MF_LOOKUP);
        }
        mutex_exit(&fnp->fn_lock);
        return (error);
}

/*
 * Starting point for thread to handle mount requests with automountd.
 * XXX auto_mount_thread() is not suspend-safe within the scope of
 * the present model defined for cpr to suspend the system. Calls
 * made by the auto_mount_thread() that have been identified to be unsafe
 * are (1) RPC client handle setup and client calls to automountd which
 * can block deep down in the RPC library, (2) kmem_alloc() calls with the
 * KM_SLEEP flag which can block if memory is low, and (3) VFS_*(), and
 * lookuppnvp() calls which can result in over the wire calls to servers.
 * The thread should be completely reevaluated to make it suspend-safe in
 * case of future updates to the cpr model.
 */
static void
auto_mount_thread(struct autofs_callargs *argsp)
{
        struct fninfo           *fnip;
        fnnode_t                *fnp;
        vnode_t                 *vp;
        char                    *name;
        size_t                  namelen;
        cred_t                  *cred;
        action_list             *alp = NULL;
        int                     error;
        callb_cpr_t             cprinfo;
        kmutex_t                auto_mount_thread_cpr_lock;

        mutex_init(&auto_mount_thread_cpr_lock, NULL, MUTEX_DEFAULT, NULL);
        CALLB_CPR_INIT(&cprinfo, &auto_mount_thread_cpr_lock,
            callb_generic_cpr, "auto_mount_thread");

        fnp = argsp->fnc_fnp;
        vp = fntovn(fnp);
        fnip = vfstofni(vp->v_vfsp);
        name = argsp->fnc_name;
        cred = argsp->fnc_cred;
        ASSERT(crgetzoneid(argsp->fnc_cred) == fnip->fi_zoneid);

        error = auto_mount_request(fnip, name, &alp, cred, TRUE);
        if (!error)
                error = auto_perform_actions(fnip, fnp, alp, cred);
        mutex_enter(&fnp->fn_lock);
        fnp->fn_error = error;

        /*
         * Notify threads waiting for mount that
         * it's done.
         */
        AUTOFS_UNBLOCK_OTHERS(fnp, MF_INPROG);
        mutex_exit(&fnp->fn_lock);

        VN_RELE(vp);
        crfree(argsp->fnc_cred);
        namelen = strlen(argsp->fnc_name) + 1;
        kmem_free(argsp->fnc_name, namelen);
        kmem_free(argsp, sizeof (*argsp));

        mutex_enter(&auto_mount_thread_cpr_lock);
        CALLB_CPR_EXIT(&cprinfo);
        mutex_destroy(&auto_mount_thread_cpr_lock);
        zthread_exit();
        /* NOTREACHED */
}

static int autofs_thr_success = 0;

/*
 * Creates new thread which calls auto_mount_thread which does
 * the bulk of the work calling automountd, via 'auto_perform_actions'.
 */
void
auto_new_mount_thread(fnnode_t *fnp, char *name, cred_t *cred)
{
        struct autofs_callargs *argsp;

        argsp = kmem_alloc(sizeof (*argsp), KM_SLEEP);
        VN_HOLD(fntovn(fnp));
        argsp->fnc_fnp = fnp;
        argsp->fnc_name = kmem_alloc(strlen(name) + 1, KM_SLEEP);
        (void) strcpy(argsp->fnc_name, name);
        argsp->fnc_origin = curthread;
        crhold(cred);
        argsp->fnc_cred = cred;

        (void) zthread_create(NULL, 0, auto_mount_thread, argsp, 0,
            minclsyspri);
        autofs_thr_success++;
}

#define DOOR_BUF_ALIGN          (1024*1024)
#define DOOR_BUF_MULTIPLIER     3
#define DOOR_BUF_DEFAULT_SZ     (DOOR_BUF_MULTIPLIER * DOOR_BUF_ALIGN)
int     doorbuf_defsz = DOOR_BUF_DEFAULT_SZ;

/*ARGSUSED*/
int
auto_calldaemon(
        zoneid_t                zoneid,
        int                     which,
        xdrproc_t               xarg_func,
        void                    *argsp,
        xdrproc_t               xresp_func,
        void                    *resp,
        int                     reslen,
        bool_t                  hard)   /* retry forever? */
{
        int                      retry;
        int                      error = 0;
        k_sigset_t               smask;
        door_arg_t               door_args;
        door_handle_t            dh;
        XDR                      xdrarg;
        XDR                      xdrres;
        struct autofs_globals   *fngp = NULL;
        void                    *orp = NULL;
        int                      orl;
        int                      rlen = 0;      /* MUST be initialized */
        autofs_door_args_t      *xdr_argsp;
        int                      xdr_len = 0;
        int                      printed_not_running_msg = 0;
        klwp_t                  *lwp = ttolwp(curthread);

        /*
         * We know that the current thread is doing work on
         * behalf of its own zone, so it's ok to use
         * curproc->p_zone.
         */
        ASSERT(zoneid == getzoneid());
        if (zone_status_get(curproc->p_zone) >= ZONE_IS_SHUTTING_DOWN) {
                /*
                 * There's no point in trying to talk to
                 * automountd.  Plus, zone_shutdown() is
                 * waiting for us.
                 */
                return (ECONNREFUSED);
        }

        do {
                retry = 0;
                mutex_enter(&autofs_minor_lock);
                fngp = zone_getspecific(autofs_key, curproc->p_zone);
                mutex_exit(&autofs_minor_lock);
                if (fngp == NULL) {
                        if (hard) {
                                AUTOFS_DPRINT((5,
                                    "auto_calldaemon: "\
                                    "failed to get door handle\n"));
                                if (!printed_not_running_msg) {
                                        printed_not_running_msg = 1;
                                        zprintf(zoneid, "automountd not "\
                                            "running, retrying\n");
                                }
                                ddi_sleep(1);
                                retry = 1;
                        } else {
                                /*
                                 * There is no global data so no door.
                                 * There's no point in attempting to talk
                                 * to automountd if we can't get the door
                                 * handle.
                                 */
                                return (ECONNREFUSED);
                        }
                }
        } while (retry);

        if (printed_not_running_msg) {
                fngp->fng_printed_not_running_msg = printed_not_running_msg;
        }

        ASSERT(fngp != NULL);

        if (argsp != NULL && (xdr_len = xdr_sizeof(xarg_func, argsp)) == 0)
                return (EINVAL);
        xdr_argsp = kmem_zalloc(xdr_len + sizeof (*xdr_argsp), KM_SLEEP);
        xdr_argsp->xdr_len = xdr_len;
        xdr_argsp->cmd = which;

        if (argsp) {
                xdrmem_create(&xdrarg, (char *)&xdr_argsp->xdr_arg,
                    xdr_argsp->xdr_len, XDR_ENCODE);

                if (!(*xarg_func)(&xdrarg, argsp)) {
                        kmem_free(xdr_argsp, xdr_len + sizeof (*xdr_argsp));
                        return (EINVAL);
                }
        }

        /*
         * We're saving off the original pointer and length due to the
         * possibility that the results buffer returned by the door
         * upcall can be different then what we passed in. This is because
         * the door will allocate new memory if the results buffer passed
         * in isn't large enough to hold what we need to send back.
         * In this case we need to free the memory originally allocated
         * for that buffer.
         */
        if (resp)
                rlen = xdr_sizeof(xresp_func, resp);
        orl = (rlen == 0) ? doorbuf_defsz : MAX(rlen, doorbuf_defsz);
        orp = kmem_zalloc(orl, KM_SLEEP);

        do {
                retry = 0;
                mutex_enter(&fngp->fng_autofs_daemon_lock);
                dh = fngp->fng_autofs_daemon_dh;
                if (dh)
                        door_ki_hold(dh);
                mutex_exit(&fngp->fng_autofs_daemon_lock);

                if (dh == NULL) {
                        if (orp)
                                kmem_free(orp, orl);
                        kmem_free(xdr_argsp, xdr_len + sizeof (*xdr_argsp));
                        return (ENOENT);
                }
                door_args.data_ptr = (char *)xdr_argsp;
                door_args.data_size = sizeof (*xdr_argsp) + xdr_argsp->xdr_len;
                door_args.desc_ptr = NULL;
                door_args.desc_num = 0;
                door_args.rbuf = orp ? (char *)orp : NULL;
                door_args.rsize = orl;

                sigintr(&smask, 1);
                error =
                    door_ki_upcall_limited(dh, &door_args, NULL, SIZE_MAX, 0);
                sigunintr(&smask);

                door_ki_rele(dh);

                /*
                 * Handle daemon errors
                 */
                if (!error) {
                        /*
                         * Upcall successful. Let's check for soft errors
                         * from the daemon. We only recover from overflow
                         * type scenarios. Any other errors, we return to
                         * the caller.
                         */
                        autofs_door_res_t *adr =
                            (autofs_door_res_t *)door_args.rbuf;

                        if (door_args.rbuf != NULL) {
                                int      nl;

                                switch (error = adr->res_status) {
                                case 0: /* no error; continue */
                                        break;

                                case EOVERFLOW:
                                        /*
                                         * orig landing buf not big enough.
                                         * xdr_len in XDR_BYTES_PER_UNIT
                                         */
                                        if ((nl = adr->xdr_len) > 0 &&
                                            (btopr(nl) < freemem/64)) {
                                                if (orp)
                                                        kmem_free(orp, orl);
                                                orp = kmem_zalloc(nl, KM_SLEEP);
                                                orl = nl;
                                                retry = 1;
                                                break;
                                        }
                                        /*FALLTHROUGH*/

                                default:
                                        kmem_free(xdr_argsp,
                                            xdr_len + sizeof (*xdr_argsp));
                                        if (orp)
                                                kmem_free(orp, orl);
                                        return (error);
                                }
                        }
                        continue;
                }

                /*
                 * no daemon errors; now process door/comm errors (if any)
                 */
                switch (error) {
                case EINTR:
                        /*
                         * interrupts should be handled properly by the
                         * door upcall. If the door doesn't handle the
                         * interupt completely then we need to bail out.
                         */
                        if (lwp && (ISSIG(curthread,
                            JUSTLOOKING) || MUSTRETURN(curproc, curthread))) {
                                if (ISSIG(curthread, FORREAL) ||
                                    lwp->lwp_sysabort ||
                                    MUSTRETURN(curproc, curthread)) {
                                        lwp->lwp_sysabort = 0;
                                        return (EINTR);
                                }
                        }
                        /*
                         * We may have gotten EINTR for other reasons
                         * like the door being revoked on us. Instead
                         * of trying to extract this out of the door
                         * handle, sleep and try again, if still
                         * revoked we will get EBADF next time
                         * through.
                         *
                         * If we have a pending cancellation and we don't
                         * have cancellation disabled, we will get EINTR
                         * forever, no matter how many times we retry,
                         * so just get out now if this is the case.
                         */
                        if (schedctl_cancel_pending())
                                break;
                        /* FALLTHROUGH */
                case EAGAIN:    /* process may be forking */
                        /*
                         * Back off for a bit
                         */
                        ddi_sleep(1);
                        retry = 1;
                        break;
                case EBADF:     /* Invalid door */
                case EINVAL:    /* Not a door, wrong target */
                        /*
                         * A fatal door error, if our failing door
                         * handle is the current door handle, clean
                         * up our state.
                         */
                        mutex_enter(&fngp->fng_autofs_daemon_lock);
                        if (dh == fngp->fng_autofs_daemon_dh) {
                                door_ki_rele(fngp->fng_autofs_daemon_dh);
                                fngp->fng_autofs_daemon_dh = NULL;
                        }
                        mutex_exit(&fngp->fng_autofs_daemon_lock);
                        AUTOFS_DPRINT((5, "auto_calldaemon error=%d\n", error));
                        if (hard) {
                                if (!fngp->fng_printed_not_running_msg) {
                                        fngp->fng_printed_not_running_msg = 1;
                                        zprintf(zoneid, "automountd not "
                                            "running, retrying\n");
                                }
                                ddi_sleep(1);
                                retry = 1;
                                break;
                        } else {
                                error = ECONNREFUSED;
                                kmem_free(xdr_argsp,
                                    xdr_len + sizeof (*xdr_argsp));
                                if (orp)
                                        kmem_free(orp, orl);
                                return (error);
                        }
                default:        /* Unknown must be fatal */
                        error = ENOENT;
                        kmem_free(xdr_argsp, xdr_len + sizeof (*xdr_argsp));
                        if (orp)
                                kmem_free(orp, orl);
                        return (error);
                }
        } while (retry);

        if (fngp->fng_printed_not_running_msg == 1) {
                fngp->fng_printed_not_running_msg = 0;
                zprintf(zoneid, "automountd OK\n");
        }

        if (orp && orl) {
                autofs_door_res_t       *door_resp;
                door_resp = (autofs_door_res_t *)door_args.rbuf;

                if ((void *)door_args.rbuf != orp)
                        kmem_free(orp, orl);

                xdrmem_create(&xdrres, (char *)&door_resp->xdr_res,
                    door_resp->xdr_len, XDR_DECODE);

                if (!((*xresp_func)(&xdrres, resp)))
                        error = EINVAL;
                kmem_free(door_args.rbuf, door_args.rsize);
        }
        kmem_free(xdr_argsp, xdr_len + sizeof (*xdr_argsp));
        return (error);
}

static int
auto_null_request(zoneid_t zoneid, bool_t hard)
{
        int error;

        AUTOFS_DPRINT((4, "\tauto_null_request\n"));

        error = auto_calldaemon(zoneid, NULLPROC,
            xdr_void, NULL, xdr_void, NULL, 0, hard);

        AUTOFS_DPRINT((5, "\tauto_null_request: error=%d\n", error));
        return (error);
}

static int
auto_lookup_request(
        fninfo_t *fnip,
        char *key,
        struct linka *lnp,
        bool_t hard,
        bool_t *mountreq,
        cred_t *cred)
{
        int                             error;
        struct autofs_globals           *fngp;
        struct autofs_lookupargs         reqst;
        autofs_lookupres                *resp;
        struct linka                    *p;


        AUTOFS_DPRINT((4, "auto_lookup_equest: path=%s name=%s\n",
            fnip->fi_path, key));

        fngp = vntofn(fnip->fi_rootvp)->fn_globals;

        reqst.map = fnip->fi_map;
        reqst.path = fnip->fi_path;

        if (fnip->fi_flags & MF_DIRECT)
                reqst.name = fnip->fi_key;
        else
                reqst.name = key;
        AUTOFS_DPRINT((4, "auto_lookup_request: using key=%s\n", reqst.name));

        reqst.subdir = fnip->fi_subdir;
        reqst.opts = fnip->fi_opts;
        reqst.isdirect = fnip->fi_flags & MF_DIRECT ? TRUE : FALSE;
        reqst.uid = crgetuid(cred);

        resp = kmem_zalloc(sizeof (*resp), KM_SLEEP);

        error = auto_calldaemon(fngp->fng_zoneid, AUTOFS_LOOKUP,
            xdr_autofs_lookupargs, &reqst, xdr_autofs_lookupres,
            (void *)resp, sizeof (autofs_lookupres), hard);

        if (error) {
                xdr_free(xdr_autofs_lookupres, (char *)resp);
                kmem_free(resp, sizeof (*resp));
                return (error);
        }

        if (!error) {
                fngp->fng_verbose = resp->lu_verbose;
                switch (resp->lu_res) {
                case AUTOFS_OK:
                        switch (resp->lu_type.action) {
                        case AUTOFS_MOUNT_RQ:
                                lnp->link = NULL;
                                lnp->dir = NULL;
                                *mountreq = TRUE;
                                break;

                        case AUTOFS_LINK_RQ:
                        p = &resp->lu_type.lookup_result_type_u.lt_linka;
                                lnp->dir = kmem_alloc(strlen(p->dir) + 1,
                                    KM_SLEEP);
                                (void) strcpy(lnp->dir, p->dir);
                                lnp->link = kmem_alloc(strlen(p->link) + 1,
                                    KM_SLEEP);
                                (void) strcpy(lnp->link, p->link);
                                break;

                        case AUTOFS_NONE:
                                lnp->link = NULL;
                                lnp->dir = NULL;
                                break;

                        default:
                                auto_log(fngp->fng_verbose, fngp->fng_zoneid,
                                    CE_WARN, "auto_lookup_request: bad action "
                                    "type %d", resp->lu_res);
                                error = ENOENT;
                        }
                        break;

                case AUTOFS_NOENT:
                        error = ENOENT;
                        break;

                default:
                        error = ENOENT;
                        auto_log(fngp->fng_verbose, fngp->fng_zoneid, CE_WARN,
                            "auto_lookup_request: unknown result: %d",
                            resp->lu_res);
                        break;
                }
        }
done:
        xdr_free(xdr_autofs_lookupres, (char *)resp);
        kmem_free(resp, sizeof (*resp));
        AUTOFS_DPRINT((5, "auto_lookup_request: path=%s name=%s error=%d\n",
            fnip->fi_path, key, error));
        return (error);
}

static int
auto_mount_request(
        fninfo_t *fnip,
        char *key,
        action_list **alpp,
        cred_t *cred,
        bool_t hard)
{
        int                     error;
        struct autofs_globals   *fngp;
        autofs_lookupargs       reqst;
        autofs_mountres         *xdrres = NULL;

        AUTOFS_DPRINT((4, "auto_mount_request: path=%s name=%s\n",
            fnip->fi_path, key));

        fngp = vntofn(fnip->fi_rootvp)->fn_globals;
        reqst.map = fnip->fi_map;
        reqst.path = fnip->fi_path;

        if (fnip->fi_flags & MF_DIRECT)
                reqst.name = fnip->fi_key;
        else
                reqst.name = key;

        AUTOFS_DPRINT((4, "auto_mount_request: using key=%s\n", reqst.name));

        reqst.subdir = fnip->fi_subdir;
        reqst.opts = fnip->fi_opts;
        reqst.isdirect = fnip->fi_flags & MF_DIRECT ? TRUE : FALSE;
        reqst.uid = crgetuid(cred);

        xdrres = kmem_zalloc(sizeof (*xdrres), KM_SLEEP);

        error = auto_calldaemon(fngp->fng_zoneid, AUTOFS_MNTINFO,
            xdr_autofs_lookupargs, &reqst, xdr_autofs_mountres,
            (void *)xdrres, sizeof (autofs_mountres), hard);

        if (!error) {
                fngp->fng_verbose = xdrres->mr_verbose;
                switch (xdrres->mr_type.status) {
                case AUTOFS_ACTION:
                        error = 0;
                        /*
                         * Save the action list since it is used by
                         * the caller. We NULL the action list pointer
                         * in 'result' so that xdr_free() will not free
                         * the list.
                         */
                        *alpp = xdrres->mr_type.mount_result_type_u.list;
                        xdrres->mr_type.mount_result_type_u.list = NULL;
                        break;
                case AUTOFS_DONE:
                        error = xdrres->mr_type.mount_result_type_u.error;
                        break;
                default:
                        error = ENOENT;
                        auto_log(fngp->fng_verbose, fngp->fng_zoneid, CE_WARN,
                            "auto_mount_request: unknown status %d",
                            xdrres->mr_type.status);
                        break;
                }
        }

        xdr_free(xdr_autofs_mountres, (char *)xdrres);
        kmem_free(xdrres, sizeof (*xdrres));


        AUTOFS_DPRINT((5, "auto_mount_request: path=%s name=%s error=%d\n",
            fnip->fi_path, key, error));
        return (error);
}


static int
auto_send_unmount_request(
        fninfo_t *fnip,
        umntrequest *ul,
        bool_t hard)
{
        int     error;
        umntres xdrres;

        struct autofs_globals *fngp = vntofn(fnip->fi_rootvp)->fn_globals;

        AUTOFS_DPRINT((4, "\tauto_send_unmount_request: fstype=%s "
            " mntpnt=%s\n", ul->fstype, ul->mntpnt));

        bzero(&xdrres, sizeof (umntres));
        error = auto_calldaemon(fngp->fng_zoneid, AUTOFS_UNMOUNT,
            xdr_umntrequest, (void *)ul, xdr_umntres, (void *)&xdrres,
            sizeof (umntres), hard);

        if (!error)
                error = xdrres.status;

        AUTOFS_DPRINT((5, "\tauto_send_unmount_request: error=%d\n", error));

        return (error);
}

static int
auto_perform_link(fnnode_t *fnp, struct linka *linkp, cred_t *cred)
{
        vnode_t *vp;
        size_t len;
        char *tmp;

        AUTOFS_DPRINT((3, "auto_perform_link: fnp=%p dir=%s link=%s\n",
            (void *)fnp, linkp->dir, linkp->link));

        len = strlen(linkp->link) + 1;          /* include '\0' */
        tmp = kmem_zalloc(len, KM_SLEEP);
        (void) kcopy(linkp->link, tmp, len);
        mutex_enter(&fnp->fn_lock);
        fnp->fn_symlink = tmp;
        fnp->fn_symlinklen = (uint_t)len;
        fnp->fn_flags |= MF_THISUID_MATCH_RQD;
        crhold(cred);
        fnp->fn_cred = cred;
        mutex_exit(&fnp->fn_lock);

        vp = fntovn(fnp);
        vp->v_type = VLNK;

        return (0);
}

static void
auto_free_autofs_args(struct mounta *m)
{
        autofs_args     *aargs = (autofs_args *)m->dataptr;

        if (aargs->addr.buf)
                kmem_free(aargs->addr.buf, aargs->addr.len);
        if (aargs->path)
                kmem_free(aargs->path, strlen(aargs->path) + 1);
        if (aargs->opts)
                kmem_free(aargs->opts, strlen(aargs->opts) + 1);
        if (aargs->map)
                kmem_free(aargs->map, strlen(aargs->map) + 1);
        if (aargs->subdir)
                kmem_free(aargs->subdir, strlen(aargs->subdir) + 1);
        if (aargs->key)
                kmem_free(aargs->key, strlen(aargs->key) + 1);
        kmem_free(aargs, sizeof (*aargs));
}

static void
auto_free_action_list(action_list *alp)
{
        struct  mounta  *m;
        action_list     *lastalp;
        char            *fstype;

        m = &alp->action.action_list_entry_u.mounta;
        while (alp != NULL) {
                fstype = alp->action.action_list_entry_u.mounta.fstype;
                m = &alp->action.action_list_entry_u.mounta;
                if (m->dataptr) {
                        if (strcmp(fstype, "autofs") == 0) {
                                auto_free_autofs_args(m);
                        }
                }
                if (m->spec)
                        kmem_free(m->spec, strlen(m->spec) + 1);
                if (m->dir)
                        kmem_free(m->dir, strlen(m->dir) + 1);
                if (m->fstype)
                        kmem_free(m->fstype, strlen(m->fstype) + 1);
                if (m->optptr)
                        kmem_free(m->optptr, m->optlen);
                lastalp = alp;
                alp = alp->next;
                kmem_free(lastalp, sizeof (*lastalp));
        }
}

static boolean_t
auto_invalid_autofs(fninfo_t *dfnip, fnnode_t *dfnp, action_list *p)
{
        struct mounta *m;
        struct autofs_args *argsp;
        vnode_t *dvp;
        char buff[AUTOFS_MAXPATHLEN];
        size_t len;
        struct autofs_globals *fngp;

        fngp = dfnp->fn_globals;
        dvp = fntovn(dfnp);

        m = &p->action.action_list_entry_u.mounta;
        /*
         * Make sure we aren't geting passed NULL values or a "dir" that
         * isn't "." and doesn't begin with "./".
         *
         * We also only want to perform autofs mounts, so make sure
         * no-one is trying to trick us into doing anything else.
         */
        if (m->spec == NULL || m->dir == NULL || m->dir[0] != '.' ||
            (m->dir[1] != '/' && m->dir[1] != '\0') ||
            m->fstype == NULL || strcmp(m->fstype, "autofs") != 0 ||
            m->dataptr == NULL || m->datalen != sizeof (struct autofs_args) ||
            m->optptr == NULL)
                return (B_TRUE);
        /*
         * We also don't like ".."s in the pathname.  Symlinks are
         * handled by the fact that we'll use NOFOLLOW when we do
         * lookup()s.
         */
        if (strstr(m->dir, "/../") != NULL ||
            (len = strlen(m->dir)) > sizeof ("/..") - 1 &&
            m->dir[len] == '.' && m->dir[len - 1] == '.' &&
            m->dir[len - 2] == '/')
                return (B_TRUE);
        argsp = (struct autofs_args *)m->dataptr;
        /*
         * We don't want NULL values here either.
         */
        if (argsp->addr.buf == NULL || argsp->path == NULL ||
            argsp->opts == NULL || argsp->map == NULL || argsp->subdir == NULL)
                return (B_TRUE);
        /*
         * We know what the claimed pathname *should* look like:
         *
         * If the parent (dfnp) is a mount point (VROOT), then
         * the path should be (dfnip->fi_path + m->dir).
         *
         * Else, we know we're only two levels deep, so we use
         * (dfnip->fi_path + dfnp->fn_name + m->dir).
         *
         * Furthermore, "." only makes sense if dfnp is a
         * trigger node.
         *
         * At this point it seems like the passed-in path is
         * redundant.
         */
        if (dvp->v_flag & VROOT) {
                if (m->dir[1] == '\0' && !(dfnp->fn_flags & MF_TRIGGER))
                        return (B_TRUE);
                (void) snprintf(buff, sizeof (buff), "%s%s",
                    dfnip->fi_path, m->dir + 1);
        } else {
                (void) snprintf(buff, sizeof (buff), "%s/%s%s",
                    dfnip->fi_path, dfnp->fn_name, m->dir + 1);
        }
        if (strcmp(argsp->path, buff) != 0) {
                auto_log(fngp->fng_verbose, fngp->fng_zoneid,
                    CE_WARN, "autofs: expected path of '%s', "
                    "got '%s' instead.", buff, argsp->path);
                return (B_TRUE);
        }
        return (B_FALSE); /* looks OK */
}

/*
 * auto_invalid_action will validate the action_list received.  If all is good
 * this function returns FALSE, if there is a problem it returns TRUE.
 */
static boolean_t
auto_invalid_action(fninfo_t *dfnip, fnnode_t *dfnp, action_list *alistpp)
{

        /*
         * Before we go any further, this better be a mount request.
         */
        if (alistpp->action.action != AUTOFS_MOUNT_RQ)
                return (B_TRUE);
        return (auto_invalid_autofs(dfnip, dfnp, alistpp));

}

static int
auto_perform_actions(
        fninfo_t *dfnip,
        fnnode_t *dfnp,
        action_list *alp,
        cred_t *cred)   /* Credentials of the caller */
{

        action_list *p;
        struct mounta           *m, margs;
        struct autofs_args              *argsp;
        int                     error, success = 0;
        vnode_t                 *mvp, *dvp, *newvp;
        fnnode_t                *newfnp, *mfnp;
        int                     auto_mount = 0;
        int                     save_triggers = 0;
        int                     update_times = 0;
        char                    *mntpnt;
        char                    buff[AUTOFS_MAXPATHLEN];
        timestruc_t             now;
        struct autofs_globals   *fngp;
        cred_t                  *zcred;

        AUTOFS_DPRINT((4, "auto_perform_actions: alp=%p\n", (void *)alp));

        fngp = dfnp->fn_globals;
        dvp = fntovn(dfnp);

        /*
         * As automountd running in a zone may be compromised, and this may be
         * an attack, we can't trust everything passed in by automountd, and we
         * need to do argument verification.  We'll issue a warning and drop
         * the request if it doesn't seem right.
         */

        for (p = alp; p != NULL; p = p->next) {
                if (auto_invalid_action(dfnip, dfnp, p)) {
                        /*
                         * This warning should be sent to the global zone,
                         * since presumably the zone administrator is the same
                         * as the attacker.
                         */
                        cmn_err(CE_WARN, "autofs: invalid action list received "
                            "by automountd in zone %s.",
                            curproc->p_zone->zone_name);
                        /*
                         * This conversation is over.
                         */
                        xdr_free(xdr_action_list, (char *)alp);
                        return (EINVAL);
                }
        }

        zcred = zone_get_kcred(getzoneid());
        ASSERT(zcred != NULL);

        if (vn_mountedvfs(dvp) != NULL) {
                /*
                 * The daemon successfully mounted a filesystem
                 * on the AUTOFS root node.
                 */
                mutex_enter(&dfnp->fn_lock);
                dfnp->fn_flags |= MF_MOUNTPOINT;
                ASSERT(dfnp->fn_dirents == NULL);
                mutex_exit(&dfnp->fn_lock);
                success++;
        } else {
                /*
                 * Clear MF_MOUNTPOINT.
                 */
                mutex_enter(&dfnp->fn_lock);
                if (dfnp->fn_flags & MF_MOUNTPOINT) {
                        AUTOFS_DPRINT((10, "autofs: clearing mountpoint "
                            "flag on %s.", dfnp->fn_name));
                        ASSERT(dfnp->fn_dirents == NULL);
                        ASSERT(dfnp->fn_trigger == NULL);
                }
                dfnp->fn_flags &= ~MF_MOUNTPOINT;
                mutex_exit(&dfnp->fn_lock);
        }

        for (p = alp; p != NULL; p = p->next) {

                vfs_t *vfsp;    /* dummy argument */
                vfs_t *mvfsp;

                auto_mount = 0;

                m = &p->action.action_list_entry_u.mounta;
                argsp = (struct autofs_args *)m->dataptr;
                ASSERT(strcmp(m->fstype, "autofs") == 0);
                /*
                 * use the parent directory's timeout since it's the
                 * one specified/inherited by automount.
                 */
                argsp->mount_to = dfnip->fi_mount_to;
                /*
                 * The mountpoint is relative, and it is guaranteed to
                 * begin with "."
                 *
                 */
                ASSERT(m->dir[0] == '.');
                if (m->dir[0] == '.' && m->dir[1] == '\0') {
                        /*
                         * mounting on the trigger node
                         */
                        mvp = dvp;
                        VN_HOLD(mvp);
                        goto mount;
                }
                /*
                 * ignore "./" in front of mountpoint
                 */
                ASSERT(m->dir[1] == '/');
                mntpnt = m->dir + 2;

                AUTOFS_DPRINT((10, "\tdfnip->fi_path=%s\n", dfnip->fi_path));
                AUTOFS_DPRINT((10, "\tdfnip->fi_flags=%x\n", dfnip->fi_flags));
                AUTOFS_DPRINT((10, "\tmntpnt=%s\n", mntpnt));

                if (dfnip->fi_flags & MF_DIRECT) {
                        AUTOFS_DPRINT((10, "\tDIRECT\n"));
                        (void) sprintf(buff, "%s/%s", dfnip->fi_path, mntpnt);
                } else {
                        AUTOFS_DPRINT((10, "\tINDIRECT\n"));
                        (void) sprintf(buff, "%s/%s/%s",
                            dfnip->fi_path, dfnp->fn_name, mntpnt);
                }

                if (vn_mountedvfs(dvp) == NULL) {
                        /*
                         * Daemon didn't mount anything on the root
                         * We have to create the mountpoint if it
                         * doesn't exist already
                         *
                         * We use the caller's credentials in case a
                         * UID-match is required
                         * (MF_THISUID_MATCH_RQD).
                         */
                        rw_enter(&dfnp->fn_rwlock, RW_WRITER);
                        error = auto_search(dfnp, mntpnt, &mfnp, cred);
                        if (error == 0) {
                                /*
                                 * AUTOFS mountpoint exists
                                 */
                                if (vn_mountedvfs(fntovn(mfnp)) != NULL) {
                                        cmn_err(CE_PANIC,
                                            "auto_perform_actions:"
                                            " mfnp=%p covered", (void *)mfnp);
                                }
                        } else {
                                /*
                                 * Create AUTOFS mountpoint
                                 */
                                ASSERT((dfnp->fn_flags & MF_MOUNTPOINT) == 0);
                                error = auto_enter(dfnp, mntpnt, &mfnp, cred);
                                ASSERT(mfnp->fn_linkcnt == 1);
                                mfnp->fn_linkcnt++;
                        }
                        if (!error)
                                update_times = 1;
                        rw_exit(&dfnp->fn_rwlock);
                        ASSERT(error != EEXIST);
                        if (!error) {
                                /*
                                 * mfnp is already held.
                                 */
                                mvp = fntovn(mfnp);
                        } else {
                                auto_log(fngp->fng_verbose, fngp->fng_zoneid,
                                    CE_WARN, "autofs: mount of %s "
                                    "failed - can't create"
                                    " mountpoint.", buff);
                                continue;
                        }
                } else {
                        /*
                         * Find mountpoint in VFS mounted here. If not
                         * found, fail the submount, though the overall
                         * mount has succeeded since the root is
                         * mounted.
                         */
                        if (error = auto_getmntpnt(dvp, mntpnt, &mvp, kcred)) {
                                auto_log(fngp->fng_verbose, fngp->fng_zoneid,
                                    CE_WARN, "autofs: mount of %s "
                                    "failed - mountpoint doesn't"
                                    " exist.", buff);
                                continue;
                        }
                        if (mvp->v_type == VLNK) {
                                auto_log(fngp->fng_verbose, fngp->fng_zoneid,
                                    CE_WARN, "autofs: %s symbolic "
                                    "link: not a valid mountpoint "
                                    "- mount failed", buff);
                                VN_RELE(mvp);
                                error = ENOENT;
                                continue;
                        }
                }
mount:
                m->flags |= MS_SYSSPACE | MS_OPTIONSTR;

                /*
                 * Copy mounta struct here so we can substitute a
                 * buffer that is large enough to hold the returned
                 * option string, if that string is longer than the
                 * input option string.
                 * This can happen if there are default options enabled
                 * that were not in the input option string.
                 */
                bcopy(m, &margs, sizeof (*m));
                margs.optptr = kmem_alloc(MAX_MNTOPT_STR, KM_SLEEP);
                margs.optlen = MAX_MNTOPT_STR;
                (void) strcpy(margs.optptr, m->optptr);
                margs.dir = argsp->path;

                /*
                 * We use the zone's kcred because we don't want the
                 * zone to be able to thus do something it wouldn't
                 * normally be able to.
                 */
                error = domount(NULL, &margs, mvp, zcred, &vfsp);
                kmem_free(margs.optptr, MAX_MNTOPT_STR);
                if (error != 0) {
                        auto_log(fngp->fng_verbose, fngp->fng_zoneid,
                            CE_WARN, "autofs: domount of %s failed "
                            "error=%d", buff, error);
                        VN_RELE(mvp);
                        continue;
                }
                VFS_RELE(vfsp);

                /*
                 * If mountpoint is an AUTOFS node, then I'm going to
                 * flag it that the Filesystem mounted on top was
                 * mounted in the kernel so that the unmount can be
                 * done inside the kernel as well.
                 * I don't care to flag non-AUTOFS mountpoints when an
                 * AUTOFS in-kernel mount was done on top, because the
                 * unmount routine already knows that such case was
                 * done in the kernel.
                 */
                if (vfs_matchops(dvp->v_vfsp, vfs_getops(mvp->v_vfsp))) {
                        mfnp = vntofn(mvp);
                        mutex_enter(&mfnp->fn_lock);
                        mfnp->fn_flags |= MF_IK_MOUNT;
                        mutex_exit(&mfnp->fn_lock);
                }

                (void) vn_vfswlock_wait(mvp);
                mvfsp = vn_mountedvfs(mvp);
                if (mvfsp != NULL) {
                        vfs_lock_wait(mvfsp);
                        vn_vfsunlock(mvp);
                        error = VFS_ROOT(mvfsp, &newvp);
                        vfs_unlock(mvfsp);
                        if (error) {
                                /*
                                 * We've dropped the locks, so let's
                                 * get the mounted vfs again in case
                                 * it changed.
                                 */
                                (void) vn_vfswlock_wait(mvp);
                                mvfsp = vn_mountedvfs(mvp);
                                if (mvfsp != NULL) {
                                        error = dounmount(mvfsp, 0, CRED());
                                        if (error) {
                                                cmn_err(CE_WARN,
                                                    "autofs: could not unmount"
                                                    " vfs=%p", (void *)mvfsp);
                                        }
                                } else
                                        vn_vfsunlock(mvp);
                                VN_RELE(mvp);
                                continue;
                        }
                } else {
                        vn_vfsunlock(mvp);
                        VN_RELE(mvp);
                        continue;
                }

                auto_mount = vfs_matchops(dvp->v_vfsp,
                    vfs_getops(newvp->v_vfsp));
                newfnp = vntofn(newvp);
                newfnp->fn_parent = dfnp;

                /*
                 * At this time we want to save the AUTOFS filesystem
                 * as a trigger node. (We only do this if the mount
                 * occurred on a node different from the root.
                 * We look at the trigger nodes during
                 * the automatic unmounting to make sure we remove them
                 * as a unit and remount them as a unit if the
                 * filesystem mounted at the root could not be
                 * unmounted.
                 */
                if (auto_mount && (error == 0) && (mvp != dvp)) {
                        save_triggers++;
                        /*
                         * Add AUTOFS mount to hierarchy
                         */
                        newfnp->fn_flags |= MF_TRIGGER;
                        rw_enter(&newfnp->fn_rwlock, RW_WRITER);
                        newfnp->fn_next = dfnp->fn_trigger;
                        rw_exit(&newfnp->fn_rwlock);
                        rw_enter(&dfnp->fn_rwlock, RW_WRITER);
                        dfnp->fn_trigger = newfnp;
                        rw_exit(&dfnp->fn_rwlock);
                        /*
                         * Don't VN_RELE(newvp) here since dfnp now
                         * holds reference to it as its trigger node.
                         */
                        AUTOFS_DPRINT((10, "\tadding trigger %s to %s\n",
                            newfnp->fn_name, dfnp->fn_name));
                        AUTOFS_DPRINT((10, "\tfirst trigger is %s\n",
                            dfnp->fn_trigger->fn_name));
                        if (newfnp->fn_next != NULL)
                                AUTOFS_DPRINT((10, "\tnext trigger is %s\n",
                                    newfnp->fn_next->fn_name));
                        else
                                AUTOFS_DPRINT((10, "\tno next trigger\n"));
                } else
                        VN_RELE(newvp);

                if (!error)
                        success++;

                if (update_times) {
                        gethrestime(&now);
                        dfnp->fn_atime = dfnp->fn_mtime = now;
                }

                VN_RELE(mvp);
        }

        if (save_triggers) {
                /*
                 * Make sure the parent can't be freed while it has triggers.
                 */
                VN_HOLD(dvp);
        }

        crfree(zcred);

done:
        /*
         * Return failure if daemon didn't mount anything, and all
         * kernel mounts attempted failed.
         */
        error = success ? 0 : ENOENT;

        if (alp != NULL) {
                if ((error == 0) && save_triggers) {
                        /*
                         * Save action_list information, so that we can use it
                         * when it comes time to remount the trigger nodes
                         * The action list is freed when the directory node
                         * containing the reference to it is unmounted in
                         * unmount_tree().
                         */
                        mutex_enter(&dfnp->fn_lock);
                        ASSERT(dfnp->fn_alp == NULL);
                        dfnp->fn_alp = alp;
                        mutex_exit(&dfnp->fn_lock);
                } else {
                        /*
                         * free the action list now,
                         */
                        xdr_free(xdr_action_list, (char *)alp);
                }
        }
        AUTOFS_DPRINT((5, "auto_perform_actions: error=%d\n", error));
        return (error);
}

fnnode_t *
auto_makefnnode(
        vtype_t type,
        vfs_t *vfsp,
        char *name,
        cred_t *cred,
        struct autofs_globals *fngp)
{
        fnnode_t *fnp;
        vnode_t *vp;
        char *tmpname;
        timestruc_t now;
        /*
         * autofs uses odd inode numbers
         * automountd uses even inode numbers
         *
         * To preserve the age-old semantics that inum+devid is unique across
         * the system, this variable must be global across zones.
         */
        static ino_t nodeid = 3;

        fnp = kmem_zalloc(sizeof (*fnp), KM_SLEEP);
        fnp->fn_vnode = vn_alloc(KM_SLEEP);

        vp = fntovn(fnp);
        tmpname = kmem_alloc(strlen(name) + 1, KM_SLEEP);
        (void) strcpy(tmpname, name);
        fnp->fn_name = &tmpname[0];
        fnp->fn_namelen = (int)strlen(tmpname) + 1;     /* include '\0' */
        fnp->fn_uid = crgetuid(cred);
        fnp->fn_gid = crgetgid(cred);
        /*
         * ".." is added in auto_enter and auto_mount.
         * "." is added in auto_mkdir and auto_mount.
         */
        /*
         * Note that fn_size and fn_linkcnt are already 0 since
         * we used kmem_zalloc to allocated fnp
         */
        fnp->fn_mode = AUTOFS_MODE;
        gethrestime(&now);
        fnp->fn_atime = fnp->fn_mtime = fnp->fn_ctime = now;
        fnp->fn_ref_time = now.tv_sec;
        mutex_enter(&autofs_nodeid_lock);
        fnp->fn_nodeid = nodeid;
        nodeid += 2;
        fnp->fn_globals = fngp;
        fngp->fng_fnnode_count++;
        mutex_exit(&autofs_nodeid_lock);
        vn_setops(vp, &auto_vnodeops);
        vp->v_type = type;
        vp->v_data = (void *)fnp;
        vp->v_vfsp = vfsp;
        mutex_init(&fnp->fn_lock, NULL, MUTEX_DEFAULT, NULL);
        rw_init(&fnp->fn_rwlock, NULL, RW_DEFAULT, NULL);
        cv_init(&fnp->fn_cv_mount, NULL, CV_DEFAULT, NULL);
        vn_exists(vp);
        return (fnp);
}


void
auto_freefnnode(fnnode_t *fnp)
{
        vnode_t *vp = fntovn(fnp);

        AUTOFS_DPRINT((4, "auto_freefnnode: fnp=%p\n", (void *)fnp));

        ASSERT(fnp->fn_linkcnt == 0);
        ASSERT(vp->v_count == 0);
        ASSERT(fnp->fn_dirents == NULL);
        ASSERT(fnp->fn_parent == NULL);

        vn_invalid(vp);
        kmem_free(fnp->fn_name, fnp->fn_namelen);
        if (fnp->fn_symlink) {
                ASSERT(fnp->fn_flags & MF_THISUID_MATCH_RQD);
                kmem_free(fnp->fn_symlink, fnp->fn_symlinklen);
        }
        if (fnp->fn_cred)
                crfree(fnp->fn_cred);
        mutex_destroy(&fnp->fn_lock);
        rw_destroy(&fnp->fn_rwlock);
        cv_destroy(&fnp->fn_cv_mount);
        vn_free(vp);

        mutex_enter(&autofs_nodeid_lock);
        fnp->fn_globals->fng_fnnode_count--;
        mutex_exit(&autofs_nodeid_lock);
        kmem_free(fnp, sizeof (*fnp));
}

void
auto_disconnect(
        fnnode_t *dfnp,
        fnnode_t *fnp)
{
        fnnode_t *tmp, **fnpp;
        vnode_t *vp = fntovn(fnp);
        timestruc_t now;

        AUTOFS_DPRINT((4,
            "auto_disconnect: dfnp=%p fnp=%p linkcnt=%d\n v_count=%d",
            (void *)dfnp, (void *)fnp, fnp->fn_linkcnt, vp->v_count));

        ASSERT(RW_WRITE_HELD(&dfnp->fn_rwlock));
        ASSERT(fnp->fn_linkcnt == 1);

        if (vn_mountedvfs(vp) != NULL) {
                cmn_err(CE_PANIC, "auto_disconnect: vp %p mounted on",
                    (void *)vp);
        }

        /*
         * Decrement by 1 because we're removing the entry in dfnp.
         */
        fnp->fn_linkcnt--;
        fnp->fn_size--;

        /*
         * only changed while holding parent's (dfnp) rw_lock
         */
        fnp->fn_parent = NULL;

        fnpp = &dfnp->fn_dirents;
        for (;;) {
                tmp = *fnpp;
                if (tmp == NULL) {
                        cmn_err(CE_PANIC,
                            "auto_disconnect: %p not in %p dirent list",
                            (void *)fnp, (void *)dfnp);
                }
                if (tmp == fnp) {
                        *fnpp = tmp->fn_next;   /* remove it from the list */
                        ASSERT(vp->v_count == 0);
                        /* child had a pointer to parent ".." */
                        dfnp->fn_linkcnt--;
                        dfnp->fn_size--;
                        break;
                }
                fnpp = &tmp->fn_next;
        }

        mutex_enter(&fnp->fn_lock);
        gethrestime(&now);
        fnp->fn_atime = fnp->fn_mtime = now;
        mutex_exit(&fnp->fn_lock);

        AUTOFS_DPRINT((5, "auto_disconnect: done\n"));
}

int
auto_enter(fnnode_t *dfnp, char *name, fnnode_t **fnpp, cred_t *cred)
{
        struct fnnode *cfnp, **spp;
        vnode_t *dvp = fntovn(dfnp);
        ushort_t offset = 0;
        ushort_t diff;

        AUTOFS_DPRINT((4, "auto_enter: dfnp=%p, name=%s ", (void *)dfnp, name));

        ASSERT(RW_WRITE_HELD(&dfnp->fn_rwlock));

        cfnp = dfnp->fn_dirents;
        if (cfnp == NULL) {
                /*
                 * offset = 0 for '.' and offset = 1 for '..'
                 */
                spp = &dfnp->fn_dirents;
                offset = 2;
        }

        for (; cfnp; cfnp = cfnp->fn_next) {
                if (strcmp(cfnp->fn_name, name) == 0) {
                        mutex_enter(&cfnp->fn_lock);
                        if (cfnp->fn_flags & MF_THISUID_MATCH_RQD) {
                                /*
                                 * "thisuser" kind of node, need to
                                 * match CREDs as well
                                 */
                                mutex_exit(&cfnp->fn_lock);
                                if (crcmp(cfnp->fn_cred, cred) == 0)
                                        return (EEXIST);
                        } else {
                                mutex_exit(&cfnp->fn_lock);
                                return (EEXIST);
                        }
                }

                if (cfnp->fn_next != NULL) {
                        diff = (ushort_t)
                            (cfnp->fn_next->fn_offset - cfnp->fn_offset);
                        ASSERT(diff != 0);
                        if (diff > 1 && offset == 0) {
                                offset = (ushort_t)cfnp->fn_offset + 1;
                                spp = &cfnp->fn_next;
                        }
                } else if (offset == 0) {
                        offset = (ushort_t)cfnp->fn_offset + 1;
                        spp = &cfnp->fn_next;
                }
        }

        *fnpp = auto_makefnnode(VDIR, dvp->v_vfsp, name, cred,
            dfnp->fn_globals);
        if (*fnpp == NULL)
                return (ENOMEM);

        /*
         * I don't hold the mutex on fnpp because I created it, and
         * I'm already holding the writers lock for it's parent
         * directory, therefore nobody can reference it without me first
         * releasing the writers lock.
         */
        (*fnpp)->fn_offset = offset;
        (*fnpp)->fn_next = *spp;
        *spp = *fnpp;
        (*fnpp)->fn_parent = dfnp;
        (*fnpp)->fn_linkcnt++;  /* parent now holds reference to entry */
        (*fnpp)->fn_size++;

        /*
         * dfnp->fn_linkcnt and dfnp->fn_size protected by dfnp->rw_lock
         */
        dfnp->fn_linkcnt++;     /* child now holds reference to parent '..' */
        dfnp->fn_size++;

        dfnp->fn_ref_time = gethrestime_sec();

        AUTOFS_DPRINT((5, "*fnpp=%p\n", (void *)*fnpp));
        return (0);
}

int
auto_search(fnnode_t *dfnp, char *name, fnnode_t **fnpp, cred_t *cred)
{
        vnode_t *dvp;
        fnnode_t *p;
        int error = ENOENT, match = 0;

        AUTOFS_DPRINT((4, "auto_search: dfnp=%p, name=%s...\n",
            (void *)dfnp, name));

        dvp = fntovn(dfnp);
        if (dvp->v_type != VDIR) {
                cmn_err(CE_PANIC, "auto_search: dvp=%p not a directory",
                    (void *)dvp);
        }

        ASSERT(RW_LOCK_HELD(&dfnp->fn_rwlock));
        for (p = dfnp->fn_dirents; p != NULL; p = p->fn_next) {
                if (strcmp(p->fn_name, name) == 0) {
                        mutex_enter(&p->fn_lock);
                        if (p->fn_flags & MF_THISUID_MATCH_RQD) {
                                /*
                                 * "thisuser" kind of node
                                 * Need to match CREDs as well
                                 */
                                mutex_exit(&p->fn_lock);
                                match = crcmp(p->fn_cred, cred) == 0;
                        } else {
                                /*
                                 * No need to check CRED
                                 */
                                mutex_exit(&p->fn_lock);
                                match = 1;
                        }
                }
                if (match) {
                        error = 0;
                        if (fnpp) {
                                *fnpp = p;
                                VN_HOLD(fntovn(*fnpp));
                        }
                        break;
                }
        }

        AUTOFS_DPRINT((5, "auto_search: error=%d\n", error));
        return (error);
}

/*
 * If dvp is mounted on, get path's vnode in the mounted on
 * filesystem.  Path is relative to dvp, ie "./path".
 * If successful, *mvp points to a the held mountpoint vnode.
 */
/* ARGSUSED */
static int
auto_getmntpnt(
        vnode_t *dvp,
        char *path,
        vnode_t **mvpp,         /* vnode for mountpoint */
        cred_t *cred)
{
        int error = 0;
        vnode_t *newvp;
        char namebuf[TYPICALMAXPATHLEN];
        struct pathname lookpn;
        vfs_t *vfsp;

        AUTOFS_DPRINT((4, "auto_getmntpnt: path=%s\n", path));

        if (error = vn_vfsrlock_wait(dvp))
                return (error);

        /*
         * Now that we have the vfswlock, check to see if dvp
         * is still mounted on.  If not, then just bail out as
         * there is no need to remount the triggers since the
         * higher level mount point has gotten unmounted.
         */
        vfsp = vn_mountedvfs(dvp);
        if (vfsp == NULL) {
                vn_vfsunlock(dvp);
                error = EBUSY;
                goto done;
        }
        /*
         * Since mounted on, lookup "path" in the new filesystem,
         * it is important that we do the filesystem jump here to
         * avoid lookuppn() calling auto_lookup on dvp and deadlock.
         */
        error = VFS_ROOT(vfsp, &newvp);
        vn_vfsunlock(dvp);
        if (error)
                goto done;

        /*
         * We do a VN_HOLD on newvp just in case the first call to
         * lookuppnvp() fails with ENAMETOOLONG.  We should still have a
         * reference to this vnode for the second call to lookuppnvp().
         */
        VN_HOLD(newvp);

        /*
         * Now create the pathname struct so we can make use of lookuppnvp,
         * and pn_getcomponent.
         * This code is similar to lookupname() in fs/lookup.c.
         */
        error = pn_get_buf(path, UIO_SYSSPACE, &lookpn,
            namebuf, sizeof (namebuf));
        if (error == 0) {
                error = lookuppnvp(&lookpn, NULL, NO_FOLLOW, NULLVPP,
                    mvpp, rootdir, newvp, cred);
        } else
                VN_RELE(newvp);
        if (error == ENAMETOOLONG) {
                /*
                 * This thread used a pathname > TYPICALMAXPATHLEN bytes long.
                 * newvp is VN_RELE'd by this call to lookuppnvp.
                 *
                 * Using 'rootdir' in a zone's context is OK here: we already
                 * ascertained that there are no '..'s in the path, and we're
                 * not following symlinks.
                 */
                if ((error = pn_get(path, UIO_SYSSPACE, &lookpn)) == 0) {
                        error = lookuppnvp(&lookpn, NULL, NO_FOLLOW, NULLVPP,
                            mvpp, rootdir, newvp, cred);
                        pn_free(&lookpn);
                } else
                        VN_RELE(newvp);
        } else {
                /*
                 * Need to release newvp here since we held it.
                 */
                VN_RELE(newvp);
        }

done:
        AUTOFS_DPRINT((5, "auto_getmntpnt: path=%s *mvpp=%p error=%d\n",
            path, (void *)*mvpp, error));
        return (error);
}

#define DEEPER(x) (((x)->fn_dirents != NULL) || \
                        (vn_mountedvfs(fntovn((x)))) != NULL)

/*
 * The caller, should have already VN_RELE'd its reference to the
 * root vnode of this filesystem.
 */
static int
auto_inkernel_unmount(vfs_t *vfsp)
{
        vnode_t *cvp = vfsp->vfs_vnodecovered;
        int error;

        AUTOFS_DPRINT((4,
            "auto_inkernel_unmount: devid=%lx mntpnt(%p) count %u\n",
            vfsp->vfs_dev, (void *)cvp, cvp->v_count));

        ASSERT(vn_vfswlock_held(cvp));

        /*
         * Perform the unmount
         * The mountpoint has already been locked by the caller.
         */
        error = dounmount(vfsp, 0, kcred);

        AUTOFS_DPRINT((5, "auto_inkernel_unmount: exit count %u\n",
            cvp->v_count));
        return (error);
}

/*
 * unmounts trigger nodes in the kernel.
 */
static void
unmount_triggers(fnnode_t *fnp, action_list **alp)
{
        fnnode_t *tp, *next;
        int error = 0;
        vfs_t *vfsp;
        vnode_t *tvp;

        AUTOFS_DPRINT((4, "unmount_triggers: fnp=%p\n", (void *)fnp));
        ASSERT(RW_WRITE_HELD(&fnp->fn_rwlock));

        *alp = fnp->fn_alp;
        next = fnp->fn_trigger;
        while ((tp = next) != NULL) {
                tvp = fntovn(tp);
                ASSERT(tvp->v_count >= 2);
                next = tp->fn_next;
                /*
                 * drop writer's lock since the unmount will end up
                 * disconnecting this node from fnp and needs to acquire
                 * the writer's lock again.
                 * next has at least a reference count >= 2 since it's
                 * a trigger node, therefore can not be accidentally freed
                 * by a VN_RELE
                 */
                rw_exit(&fnp->fn_rwlock);

                vfsp = tvp->v_vfsp;

                /*
                 * Its parent was holding a reference to it, since this
                 * is a trigger vnode.
                 */
                VN_RELE(tvp);
                if (error = auto_inkernel_unmount(vfsp)) {
                        cmn_err(CE_PANIC, "unmount_triggers: "
                            "unmount of vp=%p failed error=%d",
                            (void *)tvp, error);
                }
                /*
                 * reacquire writer's lock
                 */
                rw_enter(&fnp->fn_rwlock, RW_WRITER);
        }

        /*
         * We were holding a reference to our parent.  Drop that.
         */
        VN_RELE(fntovn(fnp));
        fnp->fn_trigger = NULL;
        fnp->fn_alp = NULL;

        AUTOFS_DPRINT((5, "unmount_triggers: finished\n"));
}

/*
 * This routine locks the mountpoint of every trigger node if they're
 * not busy, or returns EBUSY if any node is busy.
 */
static boolean_t
triggers_busy(fnnode_t *fnp)
{
        int done;
        int lck_error = 0;
        fnnode_t *tp, *t1p;
        vfs_t *vfsp;

        ASSERT(RW_WRITE_HELD(&fnp->fn_rwlock));

        for (tp = fnp->fn_trigger; tp != NULL; tp = tp->fn_next) {
                AUTOFS_DPRINT((10, "\ttrigger: %s\n", tp->fn_name));
                /* MF_LOOKUP should never be set on trigger nodes */
                ASSERT((tp->fn_flags & MF_LOOKUP) == 0);
                vfsp = fntovn(tp)->v_vfsp;

                /*
                 * The vn_vfsunlock will be done in auto_inkernel_unmount.
                 */
                lck_error = vn_vfswlock(vfsp->vfs_vnodecovered);

                if (lck_error != 0 || (tp->fn_flags & MF_INPROG) ||
                    DEEPER(tp) || ((fntovn(tp))->v_count) > 2) {
                        /*
                         * couldn't lock it because it's busy,
                         * It is mounted on or has dirents?
                         * If reference count is greater than two, then
                         * somebody else is holding a reference to this vnode.
                         * One reference is for the mountpoint, and the second
                         * is for the trigger node.
                         */
                        AUTOFS_DPRINT((10, "\ttrigger busy\n"));

                        /*
                         * Unlock previously locked mountpoints
                         */
                        for (done = 0, t1p = fnp->fn_trigger; !done;
                            t1p = t1p->fn_next) {
                                /*
                                 * Unlock all nodes previously
                                 * locked. All nodes up to 'tp'
                                 * were successfully locked. If 'lck_err' is
                                 * set, then 'tp' was not locked, and thus
                                 * should not be unlocked. If
                                 * 'lck_err' is not set, then 'tp' was
                                 * successfully locked, and it should
                                 * be unlocked.
                                 */
                                if (t1p != tp || !lck_error) {
                                        vfsp = fntovn(t1p)->v_vfsp;
                                        vn_vfsunlock(vfsp->vfs_vnodecovered);
                                }
                                done = (t1p == tp);
                        }
                        return (B_TRUE);
                }
        }

        return (B_FALSE);
}

/*
 * It is the caller's responsibility to grab the VVFSLOCK.
 * Releases the VVFSLOCK upon return.
 */
static int
unmount_node(vnode_t *cvp, int force)
{
        int error = 0;
        fnnode_t *cfnp;
        vfs_t *vfsp;
        umntrequest ul;
        fninfo_t *fnip;

        AUTOFS_DPRINT((4, "\tunmount_node cvp=%p\n", (void *)cvp));

        ASSERT(vn_vfswlock_held(cvp));
        cfnp = vntofn(cvp);
        vfsp = vn_mountedvfs(cvp);

        if (force || cfnp->fn_flags & MF_IK_MOUNT) {
                /*
                 * Mount was performed in the kernel, so
                 * do an in-kernel unmount. auto_inkernel_unmount()
                 * will vn_vfsunlock(cvp).
                 */
                error = auto_inkernel_unmount(vfsp);
        } else {
                zone_t *zone = NULL;
                refstr_t *mntpt, *resource;
                size_t mntoptslen;

                /*
                 * Get the mnttab information of the node
                 * and ask the daemon to unmount it.
                 */
                bzero(&ul, sizeof (ul));
                mntfs_getmntopts(vfsp, &ul.mntopts, &mntoptslen);
                if (ul.mntopts == NULL) {
                        auto_log(cfnp->fn_globals->fng_verbose,
                            cfnp->fn_globals->fng_zoneid, CE_WARN,
                            "unmount_node: no memory");
                        vn_vfsunlock(cvp);
                        error = ENOMEM;
                        goto done;
                }
                if (mntoptslen > AUTOFS_MAXOPTSLEN)
                        ul.mntopts[AUTOFS_MAXOPTSLEN - 1] = '\0';

                mntpt = vfs_getmntpoint(vfsp);
                ul.mntpnt = (char *)refstr_value(mntpt);
                resource = vfs_getresource(vfsp);
                ul.mntresource = (char *)refstr_value(resource);

                fnip = vfstofni(cvp->v_vfsp);
                ul.isdirect = fnip->fi_flags & MF_DIRECT ? TRUE : FALSE;

                /*
                 * Since a zone'd automountd's view of the autofs mount points
                 * differs from those in the kernel, we need to make sure we
                 * give it consistent mount points.
                 */
                ASSERT(fnip->fi_zoneid == getzoneid());
                zone = curproc->p_zone;

                if (fnip->fi_zoneid != GLOBAL_ZONEID) {
                        if (ZONE_PATH_VISIBLE(ul.mntpnt, zone)) {
                                ul.mntpnt =
                                    ZONE_PATH_TRANSLATE(ul.mntpnt, zone);
                        }
                        if (ZONE_PATH_VISIBLE(ul.mntresource, zone)) {
                                ul.mntresource =
                                    ZONE_PATH_TRANSLATE(ul.mntresource, zone);
                        }
                }

                ul.fstype = vfssw[vfsp->vfs_fstype].vsw_name;
                vn_vfsunlock(cvp);

                error = auto_send_unmount_request(fnip, &ul, FALSE);
                kmem_free(ul.mntopts, mntoptslen);
                refstr_rele(mntpt);
                refstr_rele(resource);
        }

done:
        AUTOFS_DPRINT((5, "\tunmount_node cvp=%p error=%d\n", (void *)cvp,
            error));
        return (error);
}

/*
 * return EBUSY if any thread is holding a reference to this vnode
 * other than us. Result of this function cannot be relied on, since
 * it doesn't follow proper locking rules (i.e. vp->v_vfsmountedhere
 * and fnp->fn_trigger can change throughout this function). However
 * it's good enough for rough estimation.
 */
static int
check_auto_node(vnode_t *vp)
{
        fnnode_t *fnp;
        int error = 0;
        /*
         * number of references to expect for
         * a non-busy vnode.
         */
        uint_t count;

        AUTOFS_DPRINT((4, "\tcheck_auto_node vp=%p ", (void *)vp));
        fnp = vntofn(vp);

        count = 1;              /* we are holding a reference to vp */
        if (fnp->fn_flags & MF_TRIGGER) {
                /*
                 * parent holds a pointer to us (trigger)
                 */
                count++;
        }
        if (fnp->fn_trigger != NULL) {
                /*
                 * The trigger nodes have a hold on us.
                 */
                count++;
        }
        if (vn_ismntpt(vp)) {
                /*
                 * File system is mounted on us.
                 */
                count++;
        }
        mutex_enter(&vp->v_lock);
        ASSERT(vp->v_count > 0);
        if (vp->v_flag & VROOT)
                count++;
        AUTOFS_DPRINT((10, "\tcount=%u ", vp->v_count));
        if (vp->v_count > count)
                error = EBUSY;
        mutex_exit(&vp->v_lock);

        AUTOFS_DPRINT((5, "\tcheck_auto_node error=%d ", error));
        return (error);
}

/*
 * rootvp is the root of the AUTOFS filesystem.
 * If rootvp is busy (v_count > 1) returns EBUSY.
 * else removes every vnode under this tree.
 * ASSUMPTION: Assumes that the only node which can be busy is
 * the root vnode. This filesystem better be two levels deep only,
 * the root and its immediate subdirs.
 * The daemon will "AUTOFS direct-mount" only one level below the root.
 */
static void
unmount_autofs(vnode_t *rootvp)
{
        fnnode_t *fnp, *rootfnp, *nfnp;

        AUTOFS_DPRINT((4, "\tunmount_autofs rootvp=%p ", (void *)rootvp));

        /*
         * Remove all its immediate subdirectories.
         */
        rootfnp = vntofn(rootvp);
        rw_enter(&rootfnp->fn_rwlock, RW_WRITER);
        for (fnp = rootfnp->fn_dirents; fnp != NULL; fnp = nfnp) {
                ASSERT(fntovn(fnp)->v_count == 0);
                ASSERT(fnp->fn_dirents == NULL);
                ASSERT(fnp->fn_linkcnt == 2);
                fnp->fn_linkcnt--;
                auto_disconnect(rootfnp, fnp);
                nfnp = fnp->fn_next;
                auto_freefnnode(fnp);
        }
        rw_exit(&rootfnp->fn_rwlock);
}

/*
 * If a node matches all unmount criteria, do:
 *     destroy subordinate trigger node(s) if there is any
 *     unmount filesystem mounted on top of the node if there is any
 *
 * Function should be called with locked fnp's mutex. The mutex is
 * unlocked before return from function.
 */
static int
try_unmount_node(fnnode_t *fnp, boolean_t force)
{
        boolean_t       trigger_unmount = B_FALSE;
        action_list     *alp = NULL;
        vnode_t         *vp;
        int             error = 0;
        fninfo_t        *fnip;
        vfs_t           *vfsp;
        struct autofs_globals *fngp;

        AUTOFS_DPRINT((10, "\ttry_unmount_node: processing node %p\n",
            (void *)fnp));

        ASSERT(MUTEX_HELD(&fnp->fn_lock));

        fngp = fnp->fn_globals;
        vp = fntovn(fnp);
        fnip = vfstofni(vp->v_vfsp);

        /*
         * If either a mount, lookup or another unmount of this subtree is in
         * progress, don't attempt to unmount at this time.
         */
        if (fnp->fn_flags & (MF_INPROG | MF_LOOKUP)) {
                mutex_exit(&fnp->fn_lock);
                return (EBUSY);
        }

        /*
         * Bail out if someone else is holding reference to this vnode.
         * This check isn't just an optimization (someone is probably
         * just about to trigger mount). It is necessary to prevent a deadlock
         * in domount() called from auto_perform_actions() if unmount of
         * trigger parent fails. domount() calls lookupname() to resolve
         * special in mount arguments. Special is set to a map name in case
         * of autofs triggers (i.e. auto_ws.sun.com). Thus if current
         * working directory is set to currently processed node, lookupname()
         * calls into autofs vnops in order to resolve special, which deadlocks
         * the process.
         *
         * Note: This should be fixed. Autofs shouldn't pass the map name
         * in special and avoid useless lookup with potentially disasterous
         * consequence.
         */
        if (check_auto_node(vp) == EBUSY) {
                mutex_exit(&fnp->fn_lock);
                return (EBUSY);
        }

        /*
         * If not forced operation, back out if node has been referenced
         * recently.
         */
        if (!force &&
            fnp->fn_ref_time + fnip->fi_mount_to > gethrestime_sec()) {
                mutex_exit(&fnp->fn_lock);
                return (EBUSY);
        }

        /* block mounts/unmounts on the node */
        AUTOFS_BLOCK_OTHERS(fnp, MF_INPROG);
        fnp->fn_error = 0;
        mutex_exit(&fnp->fn_lock);

        /* unmount next level triggers if there are any */
        rw_enter(&fnp->fn_rwlock, RW_WRITER);
        if (fnp->fn_trigger != NULL) {
                trigger_unmount = B_TRUE;

                if (triggers_busy(fnp)) {
                        rw_exit(&fnp->fn_rwlock);
                        mutex_enter(&fnp->fn_lock);
                        AUTOFS_UNBLOCK_OTHERS(fnp, MF_INPROG);
                        mutex_exit(&fnp->fn_lock);
                        return (EBUSY);
                }

                /*
                 * At this point, we know all trigger nodes are locked,
                 * and they're not busy or mounted on.
                 *
                 * Attempt to unmount all trigger nodes, save the
                 * action_list in case we need to remount them later.
                 * The action_list will be freed later if there was no
                 * need to remount the trigger nodes.
                 */
                unmount_triggers(fnp, &alp);
        }
        rw_exit(&fnp->fn_rwlock);

        (void) vn_vfswlock_wait(vp);

        vfsp = vn_mountedvfs(vp);
        if (vfsp != NULL) {
                /* vn_vfsunlock(vp) is done inside unmount_node() */
                error = unmount_node(vp, force);
                if (error == ECONNRESET) {
                        if (vn_mountedvfs(vp) == NULL) {
                                /*
                                 * The filesystem was unmounted before the
                                 * daemon died. Unfortunately we can not
                                 * determine whether all the cleanup work was
                                 * successfully finished (i.e. update mnttab,
                                 * or notify NFS server of the unmount).
                                 * We should not retry the operation since the
                                 * filesystem has already been unmounted, and
                                 * may have already been removed from mnttab,
                                 * in such case the devid/rdevid we send to
                                 * the daemon will not be matched. So we have
                                 * to be content with the partial unmount.
                                 * Since the mountpoint is no longer covered, we
                                 * clear the error condition.
                                 */
                                error = 0;
                                auto_log(fngp->fng_verbose, fngp->fng_zoneid,
                                    CE_WARN, "autofs: automountd "
                                    "connection dropped when unmounting %s/%s",
                                    fnip->fi_path, (fnip->fi_flags & MF_DIRECT)
                                    ? "" : fnp->fn_name);
                        }
                }
        } else {
                vn_vfsunlock(vp);
                /* Destroy all dirents of fnp if we unmounted its triggers */
                if (trigger_unmount)
                        unmount_autofs(vp);
        }

        /* If unmount failed, we got to remount triggers */
        if (error != 0) {
                if (trigger_unmount) {
                        int     ret;

                        ASSERT((fnp->fn_flags & MF_THISUID_MATCH_RQD) == 0);

                        /*
                         * The action list was free'd by auto_perform_actions
                         */
                        ret = auto_perform_actions(fnip, fnp, alp, CRED());
                        if (ret != 0) {
                                auto_log(fngp->fng_verbose, fngp->fng_zoneid,
                                    CE_WARN, "autofs: can't remount triggers "
                                    "fnp=%p error=%d", (void *)fnp, ret);
                        }
                }
                mutex_enter(&fnp->fn_lock);
                AUTOFS_UNBLOCK_OTHERS(fnp, MF_INPROG);
                mutex_exit(&fnp->fn_lock);
        } else {
                /* Free the action list here */
                if (trigger_unmount)
                        xdr_free(xdr_action_list, (char *)alp);

                /*
                 * Other threads may be waiting for this unmount to
                 * finish. We must let it know that in order to
                 * proceed, it must trigger the mount itself.
                 */
                mutex_enter(&fnp->fn_lock);
                fnp->fn_flags &= ~MF_IK_MOUNT;
                if (fnp->fn_flags & MF_WAITING)
                        fnp->fn_error = EAGAIN;
                AUTOFS_UNBLOCK_OTHERS(fnp, MF_INPROG);
                mutex_exit(&fnp->fn_lock);
        }

        return (error);
}

/*
 * This is an implementation of depth-first search in a tree rooted by
 * start_fnp and composed from fnnodes. Links between tree levels are
 * fn_dirents, fn_trigger in fnnode_t and v_mountedvfs in vnode_t (if
 * mounted vfs is autofs). The algorithm keeps track of visited nodes
 * by means of a timestamp (fn_unmount_ref_time).
 *
 * Upon top-down traversal of the tree we apply following locking scheme:
 *      lock fn_rwlock of current node
 *      grab reference to child's vnode (VN_HOLD)
 *      unlock fn_rwlock
 *      free reference to current vnode (VN_RELE)
 * Similar locking scheme is used for down-top and left-right traversal.
 *
 * Algorithm examines the most down-left node in tree, which hasn't been
 * visited yet. From this follows that nodes are processed in bottom-up
 * fashion.
 *
 * Function returns either zero if unmount of root node was successful
 * or error code (mostly EBUSY).
 */
int
unmount_subtree(fnnode_t *rootfnp, boolean_t force)
{
        fnnode_t        *currfnp; /* currently examined node in the tree */
        fnnode_t        *lastfnp; /* previously processed node */
        fnnode_t        *nextfnp; /* next examined node in the tree */
        vnode_t         *curvp;
        vnode_t         *newvp;
        vfs_t           *vfsp;
        time_t          timestamp;

        ASSERT(fntovn(rootfnp)->v_type != VLNK);
        AUTOFS_DPRINT((10, "unmount_subtree: root=%p (%s)\n", (void *)rootfnp,
            rootfnp->fn_name));

        /*
         * Timestamp, which visited nodes are marked with, to distinguish them
         * from unvisited nodes.
         */
        timestamp = gethrestime_sec();
        currfnp = lastfnp = rootfnp;

        /* Loop until we examine all nodes in the tree */
        mutex_enter(&currfnp->fn_lock);
        while (currfnp != rootfnp || rootfnp->fn_unmount_ref_time < timestamp) {
                curvp = fntovn(currfnp);
                AUTOFS_DPRINT((10, "\tunmount_subtree: entering node %p (%s)\n",
                    (void *)currfnp, currfnp->fn_name));

                /*
                 * New candidate for processing must have been already visited,
                 * by us because we want to process tree nodes in bottom-up
                 * order.
                 */
                if (currfnp->fn_unmount_ref_time == timestamp &&
                    currfnp != lastfnp) {
                        (void) try_unmount_node(currfnp, force);
                        lastfnp = currfnp;
                        mutex_enter(&currfnp->fn_lock);
                        /*
                         * Fall through to next if-branch to pick
                         * sibling or parent of this node.
                         */
                }

                /*
                 * If this node has been already visited, it means that it's
                 * dead end and we need to pick sibling or parent as next node.
                 */
                if (currfnp->fn_unmount_ref_time >= timestamp ||
                    curvp->v_type == VLNK) {
                        mutex_exit(&currfnp->fn_lock);
                        /*
                         * Obtain parent's readers lock before grabbing
                         * reference to sibling.
                         */
                        rw_enter(&currfnp->fn_parent->fn_rwlock, RW_READER);
                        if ((nextfnp = currfnp->fn_next) != NULL) {
                                VN_HOLD(fntovn(nextfnp));
                                rw_exit(&currfnp->fn_parent->fn_rwlock);
                                VN_RELE(curvp);
                                currfnp = nextfnp;
                                mutex_enter(&currfnp->fn_lock);
                                continue;
                        }
                        rw_exit(&currfnp->fn_parent->fn_rwlock);

                        /*
                         * All descendants and siblings were visited. Perform
                         * bottom-up move.
                         */
                        nextfnp = currfnp->fn_parent;
                        VN_HOLD(fntovn(nextfnp));
                        VN_RELE(curvp);
                        currfnp = nextfnp;
                        mutex_enter(&currfnp->fn_lock);
                        continue;
                }

                /*
                 * Mark node as visited. Note that the timestamp could have
                 * been updated by somebody else in the meantime.
                 */
                if (currfnp->fn_unmount_ref_time < timestamp)
                        currfnp->fn_unmount_ref_time = timestamp;

                /*
                 * Don't descent below nodes, which are being unmounted/mounted.
                 *
                 * We need to hold both locks at once: fn_lock because we need
                 * to read MF_INPROG and fn_rwlock to prevent anybody from
                 * modifying fn_trigger until its used to traverse triggers
                 * below.
                 *
                 * Acquire fn_rwlock in non-blocking mode to avoid deadlock.
                 * If it can't be acquired, then acquire locks in correct
                 * order.
                 */
                if (!rw_tryenter(&currfnp->fn_rwlock, RW_READER)) {
                        mutex_exit(&currfnp->fn_lock);
                        rw_enter(&currfnp->fn_rwlock, RW_READER);
                        mutex_enter(&currfnp->fn_lock);
                }
                if (currfnp->fn_flags & MF_INPROG) {
                        rw_exit(&currfnp->fn_rwlock);
                        continue;
                }
                mutex_exit(&currfnp->fn_lock);

                /*
                 * Examine descendants in this order: triggers, dirents, autofs
                 * mounts.
                 */

                if ((nextfnp = currfnp->fn_trigger) != NULL) {
                        VN_HOLD(fntovn(nextfnp));
                        rw_exit(&currfnp->fn_rwlock);
                        VN_RELE(curvp);
                        currfnp = nextfnp;
                        mutex_enter(&currfnp->fn_lock);
                        continue;
                }

                if ((nextfnp = currfnp->fn_dirents) != NULL) {
                        VN_HOLD(fntovn(nextfnp));
                        rw_exit(&currfnp->fn_rwlock);
                        VN_RELE(curvp);
                        currfnp = nextfnp;
                        mutex_enter(&currfnp->fn_lock);
                        continue;
                }
                rw_exit(&currfnp->fn_rwlock);

                (void) vn_vfswlock_wait(curvp);
                vfsp = vn_mountedvfs(curvp);
                if (vfsp != NULL &&
                    vfs_matchops(vfsp, vfs_getops(curvp->v_vfsp))) {
                        /*
                         * Deal with /xfn/host/jurassic alikes here...
                         *
                         * We know this call to VFS_ROOT is safe to call while
                         * holding VVFSLOCK, since it resolves to a call to
                         * auto_root().
                         */
                        if (VFS_ROOT(vfsp, &newvp)) {
                                cmn_err(CE_PANIC,
                                    "autofs: VFS_ROOT(vfs=%p) failed",
                                    (void *)vfsp);
                        }
                        vn_vfsunlock(curvp);
                        VN_RELE(curvp);
                        currfnp = vntofn(newvp);
                        mutex_enter(&currfnp->fn_lock);
                        continue;
                }
                vn_vfsunlock(curvp);
                mutex_enter(&currfnp->fn_lock);
        }

        /*
         * Now we deal with the root node (currfnp's mutex is unlocked
         * in try_unmount_node()).
         */
        return (try_unmount_node(currfnp, force));
}

/*
 * XXX unmount_tree() is not suspend-safe within the scope of
 * the present model defined for cpr to suspend the system. Calls made
 * by the unmount_tree() that have been identified to be unsafe are
 * (1) RPC client handle setup and client calls to automountd which can
 * block deep down in the RPC library, (2) kmem_alloc() calls with the
 * KM_SLEEP flag which can block if memory is low, and (3) VFS_*() and
 * VOP_*() calls which can result in over the wire calls to servers.
 * The thread should be completely reevaluated to make it suspend-safe in
 * case of future updates to the cpr model.
 */
void
unmount_tree(struct autofs_globals *fngp, boolean_t force)
{
        callb_cpr_t     cprinfo;
        kmutex_t        unmount_tree_cpr_lock;
        fnnode_t        *root, *fnp, *next;

        mutex_init(&unmount_tree_cpr_lock, NULL, MUTEX_DEFAULT, NULL);
        CALLB_CPR_INIT(&cprinfo, &unmount_tree_cpr_lock, callb_generic_cpr,
            "unmount_tree");

        /*
         * autofssys() will be calling in from the global zone and doing
         * work on the behalf of the given zone, hence we can't always
         * assert that we have the right credentials, nor that the
         * caller is always in the correct zone.
         *
         * We do, however, know that if this is a "forced unmount"
         * operation (which autofssys() does), then we won't go down to
         * the krpc layers, so we don't need to fudge with the
         * credentials.
         */
        ASSERT(force || fngp->fng_zoneid == getzoneid());

        /*
         * If automountd is not running in this zone,
         * don't attempt unmounting this round.
         */
        if (force || auto_null_request(fngp->fng_zoneid, FALSE) == 0) {
                /*
                 * Iterate over top level autofs filesystems and call
                 * unmount_subtree() for each of them.
                 */
                root = fngp->fng_rootfnnodep;
                rw_enter(&root->fn_rwlock, RW_READER);
                for (fnp = root->fn_dirents; fnp != NULL; fnp = next) {
                        VN_HOLD(fntovn(fnp));
                        rw_exit(&root->fn_rwlock);
                        (void) unmount_subtree(fnp, force);
                        rw_enter(&root->fn_rwlock, RW_READER);
                        next = fnp->fn_next;
                        VN_RELE(fntovn(fnp));
                }
                rw_exit(&root->fn_rwlock);
        }

        mutex_enter(&unmount_tree_cpr_lock);
        CALLB_CPR_EXIT(&cprinfo);
        mutex_destroy(&unmount_tree_cpr_lock);
}

static void
unmount_zone_tree(struct autofs_globals *fngp)
{
        AUTOFS_DPRINT((5, "unmount_zone_tree started. Thread created.\n"));

        unmount_tree(fngp, B_FALSE);
        mutex_enter(&fngp->fng_unmount_threads_lock);
        fngp->fng_unmount_threads--;
        mutex_exit(&fngp->fng_unmount_threads_lock);

        AUTOFS_DPRINT((5, "unmount_zone_tree done. Thread exiting.\n"));

        zthread_exit();
        /* NOTREACHED */
}

void
auto_do_unmount(struct autofs_globals *fngp)
{
        callb_cpr_t cprinfo;
        clock_t timeleft;
        zone_t *zone = curproc->p_zone;

        CALLB_CPR_INIT(&cprinfo, &fngp->fng_unmount_threads_lock,
            callb_generic_cpr, "auto_do_unmount");

        for (;;) {      /* forever */
                mutex_enter(&fngp->fng_unmount_threads_lock);
                CALLB_CPR_SAFE_BEGIN(&cprinfo);
newthread:
                mutex_exit(&fngp->fng_unmount_threads_lock);
                timeleft = zone_status_timedwait(zone, ddi_get_lbolt() +
                    autofs_unmount_thread_timer * hz, ZONE_IS_SHUTTING_DOWN);
                mutex_enter(&fngp->fng_unmount_threads_lock);

                if (timeleft != -1) {   /* didn't time out */
                        ASSERT(zone_status_get(zone) >= ZONE_IS_SHUTTING_DOWN);
                        /*
                         * zone is exiting... don't create any new threads.
                         * fng_unmount_threads_lock is released implicitly by
                         * the below.
                         */
                        CALLB_CPR_SAFE_END(&cprinfo,
                            &fngp->fng_unmount_threads_lock);
                        CALLB_CPR_EXIT(&cprinfo);
                        zthread_exit();
                        /* NOTREACHED */
                }
                if (fngp->fng_unmount_threads < autofs_unmount_threads) {
                        fngp->fng_unmount_threads++;
                        CALLB_CPR_SAFE_END(&cprinfo,
                            &fngp->fng_unmount_threads_lock);
                        mutex_exit(&fngp->fng_unmount_threads_lock);

                        (void) zthread_create(NULL, 0, unmount_zone_tree, fngp,
                            0, minclsyspri);
                } else
                        goto newthread;
        }
        /* NOTREACHED */
}

/*
 * Is nobrowse specified in option string?
 * opts should be a null ('\0') terminated string.
 * Returns non-zero if nobrowse has been specified.
 */
int
auto_nobrowse_option(char *opts)
{
        char *buf;
        char *p;
        char *t;
        int nobrowse = 0;
        int last_opt = 0;
        size_t len;

        len = strlen(opts) + 1;
        p = buf = kmem_alloc(len, KM_SLEEP);
        (void) strcpy(buf, opts);
        do {
                if (t = strchr(p, ','))
                        *t++ = '\0';
                else
                        last_opt++;
                if (strcmp(p, MNTOPT_NOBROWSE) == 0)
                        nobrowse = 1;
                else if (strcmp(p, MNTOPT_BROWSE) == 0)
                        nobrowse = 0;
                p = t;
        } while (!last_opt);
        kmem_free(buf, len);

        return (nobrowse);
}

/*
 * used to log warnings only if automountd is running
 * with verbose mode set
 */

void
auto_log(int verbose, zoneid_t zoneid, int level, const char *fmt, ...)
{
        va_list args;

        if (verbose) {
                va_start(args, fmt);
                vzcmn_err(zoneid, level, fmt, args);
                va_end(args);
        }
}

#ifdef DEBUG
static int autofs_debug = 0;

/*
 * Utilities used by both client and server
 * Standard levels:
 * 0) no debugging
 * 1) hard failures
 * 2) soft failures
 * 3) current test software
 * 4) main procedure entry points
 * 5) main procedure exit points
 * 6) utility procedure entry points
 * 7) utility procedure exit points
 * 8) obscure procedure entry points
 * 9) obscure procedure exit points
 * 10) random stuff
 * 11) all <= 1
 * 12) all <= 2
 * 13) all <= 3
 * ...
 */
/* PRINTFLIKE2 */
void
auto_dprint(int level, const char *fmt, ...)
{
        va_list args;

        if (autofs_debug == level ||
            (autofs_debug > 10 && (autofs_debug - 10) >= level)) {
                va_start(args, fmt);
                (void) vprintf(fmt, args);
                va_end(args);
        }
}
#endif /* DEBUG */