fs/dev/sdev_vnops.c

	sdev_vnops.c revision 1c4bb543a73abbf7464757d5ba7d8b84899f2408
/*
 * 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 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * vnode ops for the /dev filesystem
 *
 * - VDIR, VCHR, CBLK, and VLNK are considered must supported files
 * - VREG and VDOOR are used for some internal implementations in
 *    the global zone, e.g. devname and devfsadm communication
 * - other file types are unusual in this namespace and
 *    not supported for now
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/t_lock.h>
#include <sys/systm.h>
#include <sys/sysmacros.h>
#include <sys/user.h>
#include <sys/time.h>
#include <sys/vfs.h>
#include <sys/vnode.h>
#include <sys/vfs_opreg.h>
#include <sys/file.h>
#include <sys/fcntl.h>
#include <sys/flock.h>
#include <sys/kmem.h>
#include <sys/uio.h>
#include <sys/errno.h>
#include <sys/stat.h>
#include <sys/cred.h>
#include <sys/cred_impl.h>
#include <sys/dirent.h>
#include <sys/pathname.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <sys/policy.h>
#include <vm/hat.h>
#include <vm/seg_vn.h>
#include <vm/seg_map.h>
#include <vm/seg.h>
#include <vm/as.h>
#include <vm/page.h>
#include <sys/proc.h>
#include <sys/mode.h>
#include <sys/sunndi.h>
#include <sys/ptms.h>
#include <fs/fs_subr.h>
#include <sys/fs/dv_node.h>
#include <sys/fs/sdev_impl.h>
#include <sys/fs/sdev_node.h>

/*ARGSUSED*/
static int
sdev_open(struct vnode **vpp, int flag, struct cred *cred, caller_context_t *ct)
{
    struct sdev_node *dv = VTOSDEV(*vpp);
    struct sdev_node *ddv = dv->sdev_dotdot;
    int error = 0;

    if ((*vpp)->v_type == VDIR)
        return (0);

    if (!SDEV_IS_GLOBAL(dv))
        return (ENOTSUP);

    ASSERT((*vpp)->v_type == VREG);
    if ((*vpp)->v_type != VREG)
        return (ENOTSUP);

    ASSERT(ddv);
    rw_enter(&ddv->sdev_contents, RW_READER);
    if (dv->sdev_attrvp == NULL) {
        rw_exit(&ddv->sdev_contents);
        return (ENOENT);
    }
    error = VOP_OPEN(&(dv->sdev_attrvp), flag, cred, ct);
    rw_exit(&ddv->sdev_contents);
    return (error);
}

/*ARGSUSED1*/
static int
sdev_close(struct vnode *vp, int flag, int count,
    offset_t offset, struct cred *cred, caller_context_t *ct)
{
    struct sdev_node *dv = VTOSDEV(vp);

    if (vp->v_type == VDIR) {
        cleanlocks(vp, ttoproc(curthread)->p_pid, 0);
        cleanshares(vp, ttoproc(curthread)->p_pid);
        return (0);
    }

    if (!SDEV_IS_GLOBAL(dv))
        return (ENOTSUP);

    ASSERT(vp->v_type == VREG);
    if (vp->v_type != VREG)
        return (ENOTSUP);

    ASSERT(dv->sdev_attrvp);
    return (VOP_CLOSE(dv->sdev_attrvp, flag, count, offset, cred, ct));
}

/*ARGSUSED*/
static int
sdev_read(struct vnode *vp, struct uio *uio, int ioflag, struct cred *cred,
    struct caller_context *ct)
{
    struct sdev_node *dv = (struct sdev_node *)VTOSDEV(vp);
    int error;

    if (!SDEV_IS_GLOBAL(dv))
        return (EINVAL);

    if (vp->v_type == VDIR)
        return (EISDIR);

    /* only supporting regular files in /dev */
    ASSERT(vp->v_type == VREG);
    if (vp->v_type != VREG)
        return (EINVAL);

    ASSERT(RW_READ_HELD(&VTOSDEV(vp)->sdev_contents));
    ASSERT(dv->sdev_attrvp);
    (void) VOP_RWLOCK(dv->sdev_attrvp, 0, ct);
    error = VOP_READ(dv->sdev_attrvp, uio, ioflag, cred, ct);
    VOP_RWUNLOCK(dv->sdev_attrvp, 0, ct);
    return (error);
}

/*ARGSUSED*/
static int
sdev_write(struct vnode *vp, struct uio *uio, int ioflag, struct cred *cred,
    struct caller_context *ct)
{
    struct sdev_node *dv = VTOSDEV(vp);
    int error = 0;

    if (!SDEV_IS_GLOBAL(dv))
        return (EINVAL);

    if (vp->v_type == VDIR)
        return (EISDIR);

    /* only supporting regular files in /dev */
    ASSERT(vp->v_type == VREG);
    if (vp->v_type != VREG)
        return (EINVAL);

    ASSERT(dv->sdev_attrvp);

    (void) VOP_RWLOCK(dv->sdev_attrvp, 1, ct);
    error = VOP_WRITE(dv->sdev_attrvp, uio, ioflag, cred, ct);
    VOP_RWUNLOCK(dv->sdev_attrvp, 1, ct);
    if (error == 0) {
        sdev_update_timestamps(dv->sdev_attrvp, kcred,
            AT_MTIME);
    }
    return (error);
}

/*ARGSUSED*/
static int
sdev_ioctl(struct vnode *vp, int cmd, intptr_t arg, int flag,
    struct cred *cred, int *rvalp,  caller_context_t *ct)
{
    struct sdev_node *dv = VTOSDEV(vp);

    if (!SDEV_IS_GLOBAL(dv) || (vp->v_type == VDIR))
        return (ENOTTY);

    ASSERT(vp->v_type == VREG);
    if (vp->v_type != VREG)
        return (EINVAL);

    ASSERT(dv->sdev_attrvp);
    return (VOP_IOCTL(dv->sdev_attrvp, cmd, arg, flag, cred, rvalp, ct));
}

static int
sdev_getattr(struct vnode *vp, struct vattr *vap, int flags,
    struct cred *cr, caller_context_t *ct)
{
    int         error = 0;
    struct sdev_node    *dv = VTOSDEV(vp);
    struct sdev_node    *parent = dv->sdev_dotdot;
    struct devname_nsmap *map = NULL;
    struct devname_ops  *dirops = NULL;
    int (*fn)(devname_handle_t *, struct vattr *, struct cred *);

    ASSERT(parent);

    rw_enter(&parent->sdev_contents, RW_READER);
    ASSERT(dv->sdev_attr || dv->sdev_attrvp);
    if (SDEV_IS_GLOBAL(dv) && (dv->sdev_state != SDEV_ZOMBIE)) {
        map = sdev_get_map(parent, 0);
        dirops = map ? map->dir_ops : NULL;
    }

    /*
     * search order:
     *  - for persistent nodes (SDEV_PERSIST): backstore
     *  - for non-persistent nodes: module ops if global, then memory
     */
    if (dv->sdev_attrvp) {
        rw_exit(&parent->sdev_contents);
        error = VOP_GETATTR(dv->sdev_attrvp, vap, flags, cr, ct);
        sdev_vattr_merge(dv, vap);
    } else if (dirops && (fn = dirops->devnops_getattr)) {
        sdev_vattr_merge(dv, vap);
        rw_exit(&parent->sdev_contents);
        error = (*fn)(&(dv->sdev_handle), vap, cr);
    } else {
        ASSERT(dv->sdev_attr);
        *vap = *dv->sdev_attr;
        sdev_vattr_merge(dv, vap);
        rw_exit(&parent->sdev_contents);
    }

    return (error);
}

/*ARGSUSED4*/
static int
sdev_setattr(struct vnode *vp, struct vattr *vap, int flags,
    struct cred *cred, caller_context_t *ctp)
{
    return (devname_setattr_func(vp, vap, flags, cred, NULL, 0));
}

static int
sdev_getsecattr(struct vnode *vp, struct vsecattr *vsap, int flags,
    struct cred *cr, caller_context_t *ct)
{
    int error;
    struct sdev_node *dv = VTOSDEV(vp);
    struct vnode *avp = dv->sdev_attrvp;

    if (avp == NULL) {
        /* return fs_fab_acl() if flavor matches, else do nothing */
        if ((SDEV_ACL_FLAVOR(vp) == _ACL_ACLENT_ENABLED &&
            (vsap->vsa_mask & (VSA_ACLCNT | VSA_DFACLCNT))) ||
            (SDEV_ACL_FLAVOR(vp) == _ACL_ACE_ENABLED &&
            (vsap->vsa_mask & (VSA_ACECNT | VSA_ACE))))
            return (fs_fab_acl(vp, vsap, flags, cr, ct));

        return (ENOSYS);
    }

    (void) VOP_RWLOCK(avp, 1, ct);
    error = VOP_GETSECATTR(avp, vsap, flags, cr, ct);
    VOP_RWUNLOCK(avp, 1, ct);
    return (error);
}

static int
sdev_setsecattr(struct vnode *vp, struct vsecattr *vsap, int flags,
    struct cred *cr, caller_context_t *ct)
{
    int error;
    struct sdev_node *dv = VTOSDEV(vp);
    struct vnode *avp = dv->sdev_attrvp;

    if (dv->sdev_state == SDEV_ZOMBIE)
        return (0);

    if (avp == NULL) {
        if (SDEV_IS_GLOBAL(dv) && !SDEV_IS_PERSIST(dv))
            return (fs_nosys());
        ASSERT(dv->sdev_attr);
        /*
         * if coming in directly, the acl system call will
         * have held the read-write lock via VOP_RWLOCK()
         * If coming in via specfs, specfs will have
         * held the rw lock on the realvp i.e. us.
         */
        ASSERT(RW_WRITE_HELD(&dv->sdev_contents));
        sdev_vattr_merge(dv, dv->sdev_attr);
        error = sdev_shadow_node(dv, cr);
        if (error) {
            return (fs_nosys());
        }

        ASSERT(dv->sdev_attrvp);
        /* clean out the memory copy if any */
        if (dv->sdev_attr) {
            kmem_free(dv->sdev_attr, sizeof (struct vattr));
            dv->sdev_attr = NULL;
        }
        avp = dv->sdev_attrvp;
    }
    ASSERT(avp);

    (void) VOP_RWLOCK(avp, V_WRITELOCK_TRUE, ct);
    error = VOP_SETSECATTR(avp, vsap, flags, cr, ct);
    VOP_RWUNLOCK(avp, V_WRITELOCK_TRUE, ct);
    return (error);
}

int
sdev_unlocked_access(void *vdv, int mode, struct cred *cr)
{
    struct sdev_node    *dv = vdv;
    int         shift = 0;
    uid_t           owner = dv->sdev_attr->va_uid;

    if (crgetuid(cr) != owner) {
        shift += 3;
        if (groupmember(dv->sdev_attr->va_gid, cr) == 0)
            shift += 3;
    }

    mode &= ~(dv->sdev_attr->va_mode << shift);
    if (mode == 0)
        return (0);

    return (secpolicy_vnode_access(cr, SDEVTOV(dv), owner, mode));
}

static int
sdev_access(struct vnode *vp, int mode, int flags, struct cred *cr,
    caller_context_t *ct)
{
    struct sdev_node    *dv = VTOSDEV(vp);
    int ret = 0;

    ASSERT(dv->sdev_attr || dv->sdev_attrvp);

    if (dv->sdev_attrvp) {
        ret = VOP_ACCESS(dv->sdev_attrvp, mode, flags, cr, ct);
    } else if (dv->sdev_attr) {
        rw_enter(&dv->sdev_contents, RW_READER);
        ret = sdev_unlocked_access(dv, mode, cr);
        if (ret)
            ret = EACCES;
        rw_exit(&dv->sdev_contents);
    }

    return (ret);
}

/*
 * Lookup
 */
/*ARGSUSED3*/
static int
sdev_lookup(struct vnode *dvp, char *nm, struct vnode **vpp,
    struct pathname *pnp, int flags, struct vnode *rdir, struct cred *cred,
    caller_context_t *ct, int *direntflags, pathname_t *realpnp)
{
    struct sdev_node *parent;
    int error;

    parent = VTOSDEV(dvp);
    ASSERT(parent);

    /* execute access is required to search the directory */
    if ((error = VOP_ACCESS(dvp, VEXEC, 0, cred, ct)) != 0)
        return (error);

    if (!SDEV_IS_GLOBAL(parent))
        return (prof_lookup(dvp, nm, vpp, cred));
    return (devname_lookup_func(parent, nm, vpp, cred, NULL, 0));
}

/*ARGSUSED2*/
static int
sdev_create(struct vnode *dvp, char *nm, struct vattr *vap, vcexcl_t excl,
    int mode, struct vnode **vpp, struct cred *cred, int flag,
    caller_context_t *ct, vsecattr_t *vsecp)
{
    struct vnode        *vp = NULL;
    struct vnode        *avp;
    struct sdev_node    *parent;
    struct sdev_node    *self = NULL;
    int         error = 0;
    vtype_t         type = vap->va_type;

    ASSERT(type != VNON && type != VBAD);

    if ((type == VFIFO) || (type == VSOCK) ||
        (type == VPROC) || (type == VPORT))
        return (ENOTSUP);

    parent = VTOSDEV(dvp);
    ASSERT(parent);

    rw_enter(&parent->sdev_dotdot->sdev_contents, RW_READER);
    if (parent->sdev_state == SDEV_ZOMBIE) {
        rw_exit(&parent->sdev_dotdot->sdev_contents);
        return (ENOENT);
    }

    /* non-global do not allow pure node creation */
    if (!SDEV_IS_GLOBAL(parent)) {
        rw_exit(&parent->sdev_dotdot->sdev_contents);
        return (prof_lookup(dvp, nm, vpp, cred));
    }
    rw_exit(&parent->sdev_dotdot->sdev_contents);

    /* execute access is required to search the directory */
    if ((error = VOP_ACCESS(dvp, VEXEC, 0, cred, ct)) != 0)
        return (error);

    /* check existing name */
/* XXXci - We may need to translate the C-I flags on VOP_LOOKUP */
    error = VOP_LOOKUP(dvp, nm, &vp, NULL, 0, NULL, cred, ct, NULL, NULL);

    /* name found */
    if (error == 0) {
        ASSERT(vp);
        if (excl == EXCL) {
            error = EEXIST;
        } else if ((vp->v_type == VDIR) && (mode & VWRITE)) {
            /* allowing create/read-only an existing directory */
            error = EISDIR;
        } else {
            error = VOP_ACCESS(vp, mode, 0, cred, ct);
        }

        if (error) {
            VN_RELE(vp);
            return (error);
        }

        /* truncation first */
        if ((vp->v_type == VREG) && (vap->va_mask & AT_SIZE) &&
            (vap->va_size == 0)) {
            ASSERT(parent->sdev_attrvp);
            error = VOP_CREATE(parent->sdev_attrvp,
                nm, vap, excl, mode, &avp, cred, flag, ct, vsecp);

            if (error) {
                VN_RELE(vp);
                return (error);
            }
        }

        sdev_update_timestamps(vp, kcred,
            AT_CTIME|AT_MTIME|AT_ATIME);
        *vpp = vp;
        return (0);
    }

    /* bail out early */
    if (error != ENOENT)
        return (error);

    /* verify write access - compliance specifies ENXIO */
    if ((error = VOP_ACCESS(dvp, VEXEC|VWRITE, 0, cred, ct)) != 0) {
        if (error == EACCES)
            error = ENXIO;
        return (error);
    }

    /*
     * For memory-based (ROFS) directory:
     *  - either disallow node creation;
     *  - or implement VOP_CREATE of its own
     */
    rw_enter(&parent->sdev_contents, RW_WRITER);
    if (!SDEV_IS_PERSIST(parent)) {
        rw_exit(&parent->sdev_contents);
        return (ENOTSUP);
    }
    ASSERT(parent->sdev_attrvp);
    error = sdev_mknode(parent, nm, &self, vap, NULL, NULL,
        cred, SDEV_READY);
    if (error) {
        rw_exit(&parent->sdev_contents);
        if (self)
            SDEV_RELE(self);
        return (error);
    }
    rw_exit(&parent->sdev_contents);

    ASSERT(self);
    /* take care the timestamps for the node and its parent */
    sdev_update_timestamps(SDEVTOV(self), kcred,
        AT_CTIME|AT_MTIME|AT_ATIME);
    sdev_update_timestamps(dvp, kcred, AT_MTIME|AT_ATIME);
    if (SDEV_IS_GLOBAL(parent))
        atomic_inc_ulong(&parent->sdev_gdir_gen);

    /* wake up other threads blocked on looking up this node */
    mutex_enter(&self->sdev_lookup_lock);
    SDEV_UNBLOCK_OTHERS(self, SDEV_LOOKUP);
    mutex_exit(&self->sdev_lookup_lock);
    error = sdev_to_vp(self, vpp);
    return (error);
}

static int
sdev_remove(struct vnode *dvp, char *nm, struct cred *cred,
    caller_context_t *ct, int flags)
{
    int error;
    struct sdev_node *parent = (struct sdev_node *)VTOSDEV(dvp);
    struct vnode *vp = NULL;
    struct sdev_node *dv = NULL;
    struct devname_nsmap *map = NULL;
    struct devname_ops *dirops = NULL;
    int (*fn)(devname_handle_t *);
    int len;
    int bkstore = 0;

    /* bail out early */
    len = strlen(nm);
    if (nm[0] == '.') {
        if (len == 1) {
            return (EINVAL);
        } else if (len == 2 && nm[1] == '.') {
            return (EEXIST);
        }
    }

    ASSERT(parent);
    rw_enter(&parent->sdev_contents, RW_READER);
    if (!SDEV_IS_GLOBAL(parent)) {
        rw_exit(&parent->sdev_contents);
        return (ENOTSUP);
    }

    /* execute access is required to search the directory */
    if ((error = VOP_ACCESS(dvp, VEXEC, 0, cred, ct)) != 0) {
        rw_exit(&parent->sdev_contents);
        return (error);
    }

    /* check existence first */
    dv = sdev_cache_lookup(parent, nm);
    if (dv == NULL) {
        rw_exit(&parent->sdev_contents);
        return (ENOENT);
    }

    vp = SDEVTOV(dv);
    if ((dv->sdev_state == SDEV_INIT) ||
        (dv->sdev_state == SDEV_ZOMBIE)) {
        rw_exit(&parent->sdev_contents);
        VN_RELE(vp);
        return (ENOENT);
    }

    /* write access is required to remove an entry */
    if ((error = VOP_ACCESS(dvp, VWRITE, 0, cred, ct)) != 0) {
        rw_exit(&parent->sdev_contents);
        VN_RELE(vp);
        return (error);
    }

    /* the module may record/reject removing a device node */
    map = sdev_get_map(parent, 0);
    dirops = map ? map->dir_ops : NULL;
    if (dirops && ((fn = dirops->devnops_remove) != NULL)) {
        error = (*fn)(&(dv->sdev_handle));
        if (error) {
            rw_exit(&parent->sdev_contents);
            VN_RELE(vp);
            return (error);
        }
    }

    /*
     * sdev_dirdelete does the real job of:
     *  - make sure no open ref count
     *  - destroying the sdev_node
     *  - releasing the hold on attrvp
     */
    bkstore = SDEV_IS_PERSIST(dv) ? 1 : 0;
    if (!rw_tryupgrade(&parent->sdev_contents)) {
        rw_exit(&parent->sdev_contents);
        rw_enter(&parent->sdev_contents, RW_WRITER);
    }
    error = sdev_cache_update(parent, &dv, nm, SDEV_CACHE_DELETE);
    rw_exit(&parent->sdev_contents);

    sdcmn_err2(("sdev_remove: cache_update error %d\n", error));
    if (error && (error != EBUSY)) {
        /* report errors other than EBUSY */
        VN_RELE(vp);
    } else {
        sdcmn_err2(("sdev_remove: cleaning node %s from cache "
            " with error %d\n", nm, error));

        /*
         * best efforts clean up the backing store
         */
        if (bkstore) {
            ASSERT(parent->sdev_attrvp);
            error = VOP_REMOVE(parent->sdev_attrvp, nm, cred,
                ct, flags);
            /*
             * do not report BUSY error
             * because the backing store ref count is released
             * when the last ref count on the sdev_node is
             * released.
             */
            if (error == EBUSY) {
                sdcmn_err2(("sdev_remove: device %s is still on"
                    "disk %s\n", nm, parent->sdev_path));
                error = 0;
            }
        }

        if (error == EBUSY)
            error = 0;
    }

    return (error);
}

/*
 * Some restrictions for this file system:
 *  - both oldnm and newnm are in the scope of /dev file system,
 *    to simply the namespace management model.
 */
/*ARGSUSED6*/
static int
sdev_rename(struct vnode *odvp, char *onm, struct vnode *ndvp, char *nnm,
    struct cred *cred, caller_context_t *ct, int flags)
{
    struct sdev_node    *fromparent = NULL;
    struct vattr        vattr;
    struct sdev_node    *toparent;
    struct sdev_node    *fromdv = NULL; /* source node */
    struct vnode        *ovp = NULL;    /* source vnode */
    struct sdev_node    *todv = NULL;   /* destination node */
    struct vnode        *nvp = NULL;    /* destination vnode */
    int         samedir = 0;    /* set if odvp == ndvp */
    struct vnode        *realvp;
    int         len;
    char            nnm_path[MAXPATHLEN];
    struct devname_nsmap    *omap = NULL;
    struct devname_ops  *odirops = NULL;
    int (*fn)(devname_handle_t *, char *);
    int (*rmfn)(devname_handle_t *);
    int error = 0;
    dev_t fsid;
    int bkstore = 0;
    vtype_t type;

    /* prevent modifying "." and ".." */
    if ((onm[0] == '.' &&
        (onm[1] == '\0' || (onm[1] == '.' && onm[2] == '\0'))) ||
        (nnm[0] == '.' &&
        (nnm[1] == '\0' || (nnm[1] == '.' && nnm[2] == '\0')))) {
        return (EINVAL);
    }

    fromparent = VTOSDEV(odvp);
    toparent = VTOSDEV(ndvp);

    /* ZOMBIE parent doesn't allow new node creation */
    rw_enter(&fromparent->sdev_dotdot->sdev_contents, RW_READER);
    if (fromparent->sdev_state == SDEV_ZOMBIE) {
        rw_exit(&fromparent->sdev_dotdot->sdev_contents);
        return (ENOENT);
    }

    /* renaming only supported for global device nodes */
    if (!SDEV_IS_GLOBAL(fromparent)) {
        rw_exit(&fromparent->sdev_dotdot->sdev_contents);
        return (ENOTSUP);
    }
    rw_exit(&fromparent->sdev_dotdot->sdev_contents);

    rw_enter(&toparent->sdev_dotdot->sdev_contents, RW_READER);
    if (toparent->sdev_state == SDEV_ZOMBIE) {
        rw_exit(&toparent->sdev_dotdot->sdev_contents);
        return (ENOENT);
    }
    rw_exit(&toparent->sdev_dotdot->sdev_contents);

    /*
     * acquire the global lock to prevent
     * mount/unmount/other rename activities.
     */
    mutex_enter(&sdev_lock);

    /* check existence of the source node */
/* XXXci - We may need to translate the C-I flags on VOP_LOOKUP */
    error = VOP_LOOKUP(odvp, onm, &ovp, NULL, 0, NULL, cred, ct,
        NULL, NULL);
    if (error) {
        sdcmn_err2(("sdev_rename: the source node %s exists\n",
            onm));
        mutex_exit(&sdev_lock);
        return (error);
    }

    if (VOP_REALVP(ovp, &realvp, ct) == 0) {
        VN_HOLD(realvp);
        VN_RELE(ovp);
        ovp = realvp;
    }

    /* check existence of destination */
/* XXXci - We may need to translate the C-I flags on VOP_LOOKUP */
    error = VOP_LOOKUP(ndvp, nnm, &nvp, NULL, 0, NULL, cred, ct,
        NULL, NULL);
    if (error && (error != ENOENT)) {
        mutex_exit(&sdev_lock);
        VN_RELE(ovp);
        return (error);
    }

    if (nvp && (VOP_REALVP(nvp, &realvp, ct) == 0)) {
        VN_HOLD(realvp);
        VN_RELE(nvp);
        nvp = realvp;
    }

    /*
     * make sure the source and the destination are
     * in the same dev filesystem
     */
    if (odvp != ndvp) {
        vattr.va_mask = AT_FSID;
        if (error = VOP_GETATTR(odvp, &vattr, 0, cred, ct)) {
            mutex_exit(&sdev_lock);
            VN_RELE(ovp);
            return (error);
        }
        fsid = vattr.va_fsid;
        vattr.va_mask = AT_FSID;
        if (error = VOP_GETATTR(ndvp, &vattr, 0, cred, ct)) {
            mutex_exit(&sdev_lock);
            VN_RELE(ovp);
            return (error);
        }
        if (fsid != vattr.va_fsid) {
            mutex_exit(&sdev_lock);
            VN_RELE(ovp);
            return (EXDEV);
        }
    }

    /* make sure the old entry can be deleted */
    error = VOP_ACCESS(odvp, VWRITE, 0, cred, ct);
    if (error) {
        mutex_exit(&sdev_lock);
        VN_RELE(ovp);
        return (error);
    }

    /* make sure the destination allows creation */
    samedir = (fromparent == toparent);
    if (!samedir) {
        error = VOP_ACCESS(ndvp, VEXEC|VWRITE, 0, cred, ct);
        if (error) {
            mutex_exit(&sdev_lock);
            VN_RELE(ovp);
            return (error);
        }
    }

    fromdv = VTOSDEV(ovp);
    ASSERT(fromdv);

    /* check with the plug-in modules for the source directory */
    rw_enter(&fromparent->sdev_contents, RW_READER);
    omap = sdev_get_map(fromparent, 0);
    rw_exit(&fromparent->sdev_contents);
    odirops = omap ? omap->dir_ops : NULL;
    if (odirops && ((fn = odirops->devnops_rename) != NULL)) {
        if (samedir) {
            error = (*fn)(&(fromdv->sdev_handle), nnm);
        } else {
            len = strlen(nnm) + strlen(toparent->sdev_name) + 2;
            (void) snprintf(nnm_path, len, "%s/%s",
                toparent->sdev_name, nnm);
            error = (*fn)(&(fromdv->sdev_handle), nnm);
        }

        if (error) {
            mutex_exit(&sdev_lock);
            sdcmn_err2(("sdev_rename: DBNR doesn't "
                "allow rename, error %d", error));
            VN_RELE(ovp);
            return (error);
        }
    }

    /* destination file exists */
    if (nvp) {
        todv = VTOSDEV(nvp);
        ASSERT(todv);
    }

    /*
     * link source to new target in the memory
     */
    error = sdev_rnmnode(fromparent, fromdv, toparent, &todv, nnm, cred);
    if (error) {
        sdcmn_err2(("sdev_rename: renaming %s to %s failed "
            " with error %d\n", onm, nnm, error));
        mutex_exit(&sdev_lock);
        if (nvp)
            VN_RELE(nvp);
        VN_RELE(ovp);
        return (error);
    }

    /* notify the DBNR module the node is going away */
    if (odirops && ((rmfn = odirops->devnops_remove) != NULL)) {
        (void) (*rmfn)(&(fromdv->sdev_handle));
    }

    /*
     * unlink from source
     */
    rw_enter(&fromparent->sdev_contents, RW_READER);
    fromdv = sdev_cache_lookup(fromparent, onm);
    if (fromdv == NULL) {
        rw_exit(&fromparent->sdev_contents);
        mutex_exit(&sdev_lock);
        sdcmn_err2(("sdev_rename: the source is deleted already\n"));
        return (0);
    }

    if (fromdv->sdev_state == SDEV_ZOMBIE) {
        rw_exit(&fromparent->sdev_contents);
        mutex_exit(&sdev_lock);
        VN_RELE(SDEVTOV(fromdv));
        sdcmn_err2(("sdev_rename: the source is being deleted\n"));
        return (0);
    }
    rw_exit(&fromparent->sdev_contents);
    ASSERT(SDEVTOV(fromdv) == ovp);
    VN_RELE(ovp);

    /* clean out the directory contents before it can be removed */
    type = SDEVTOV(fromdv)->v_type;
    if (type == VDIR) {
        error = sdev_cleandir(fromdv, NULL, 0);
        sdcmn_err2(("sdev_rename: cleandir finished with %d\n",
            error));
        if (error == EBUSY)
            error = 0;
    }

    rw_enter(&fromparent->sdev_contents, RW_WRITER);
    bkstore = SDEV_IS_PERSIST(fromdv) ? 1 : 0;
    error = sdev_cache_update(fromparent, &fromdv, onm,
        SDEV_CACHE_DELETE);

    /* best effforts clean up the backing store */
    if (bkstore) {
        ASSERT(fromparent->sdev_attrvp);
        if (type != VDIR) {
/* XXXci - We may need to translate the C-I flags on VOP_REMOVE */
            error = VOP_REMOVE(fromparent->sdev_attrvp,
                onm, kcred, ct, 0);
        } else {
/* XXXci - We may need to translate the C-I flags on VOP_RMDIR */
            error = VOP_RMDIR(fromparent->sdev_attrvp,
                onm, fromparent->sdev_attrvp, kcred, ct, 0);
        }

        if (error) {
            sdcmn_err2(("sdev_rename: device %s is "
                "still on disk %s\n", onm,
                fromparent->sdev_path));
            error = 0;
        }
    }
    rw_exit(&fromparent->sdev_contents);
    mutex_exit(&sdev_lock);

    /* once reached to this point, the rename is regarded successful */
    return (0);
}

/*
 * dev-fs version of "ln -s path dev-name"
 *  tnm - path, e.g. /devices/... or /dev/...
 *  lnm - dev_name
 */
/*ARGSUSED6*/
static int
sdev_symlink(struct vnode *dvp, char *lnm, struct vattr *tva,
    char *tnm, struct cred *cred, caller_context_t *ct, int flags)
{
    int error;
    struct vnode *vp = NULL;
    struct sdev_node *parent = (struct sdev_node *)VTOSDEV(dvp);
    struct sdev_node *self = (struct sdev_node *)NULL;

    ASSERT(parent);
    rw_enter(&parent->sdev_dotdot->sdev_contents, RW_READER);
    if (parent->sdev_state == SDEV_ZOMBIE) {
        rw_exit(&parent->sdev_dotdot->sdev_contents);
        sdcmn_err2(("sdev_symlink: parent %s is ZOMBIED \n",
            parent->sdev_name));
        return (ENOENT);
    }

    if (!SDEV_IS_GLOBAL(parent)) {
        rw_exit(&parent->sdev_dotdot->sdev_contents);
        return (ENOTSUP);
    }
    rw_exit(&parent->sdev_dotdot->sdev_contents);

    /* execute access is required to search a directory */
    if ((error = VOP_ACCESS(dvp, VEXEC, 0, cred, ct)) != 0)
        return (error);

    /* find existing name */
/* XXXci - We may need to translate the C-I flags here */
    error = VOP_LOOKUP(dvp, lnm, &vp, NULL, 0, NULL, cred, ct, NULL, NULL);
    if (error == 0) {
        ASSERT(vp);
        VN_RELE(vp);
        sdcmn_err2(("sdev_symlink: node %s already exists\n", lnm));
        return (EEXIST);
    }
    if (error != ENOENT)
        return (error);

    /* write access is required to create a symlink */
    if ((error = VOP_ACCESS(dvp, VWRITE, 0, cred, ct)) != 0)
        return (error);

    /* put it into memory cache */
    rw_enter(&parent->sdev_contents, RW_WRITER);
    error = sdev_mknode(parent, lnm, &self, tva, NULL, (void *)tnm,
        cred, SDEV_READY);
    if (error) {
        rw_exit(&parent->sdev_contents);
        sdcmn_err2(("sdev_symlink: node %s creation failed\n", lnm));
        if (self)
            SDEV_RELE(self);

        return (error);
    }
    ASSERT(self && (self->sdev_state == SDEV_READY));
    rw_exit(&parent->sdev_contents);

    /* take care the timestamps for the node and its parent */
    sdev_update_timestamps(SDEVTOV(self), kcred,
        AT_CTIME|AT_MTIME|AT_ATIME);
    sdev_update_timestamps(dvp, kcred, AT_MTIME|AT_ATIME);
    if (SDEV_IS_GLOBAL(parent))
        atomic_inc_ulong(&parent->sdev_gdir_gen);

    /* wake up other threads blocked on looking up this node */
    mutex_enter(&self->sdev_lookup_lock);
    SDEV_UNBLOCK_OTHERS(self, SDEV_LOOKUP);
    mutex_exit(&self->sdev_lookup_lock);
    SDEV_RELE(self);    /* don't return with vnode held */
    return (0);
}

/*ARGSUSED6*/
static int
sdev_mkdir(struct vnode *dvp, char *nm, struct vattr *va, struct vnode **vpp,
    struct cred *cred, caller_context_t *ct, int flags, vsecattr_t *vsecp)
{
    int error;
    struct sdev_node *parent = (struct sdev_node *)VTOSDEV(dvp);
    struct sdev_node *self = NULL;
    struct vnode    *vp = NULL;

    ASSERT(parent && parent->sdev_dotdot);
    rw_enter(&parent->sdev_dotdot->sdev_contents, RW_READER);
    if (parent->sdev_state == SDEV_ZOMBIE) {
        rw_exit(&parent->sdev_dotdot->sdev_contents);
        return (ENOENT);
    }

    /* non-global do not allow pure directory creation */
    if (!SDEV_IS_GLOBAL(parent)) {
        rw_exit(&parent->sdev_dotdot->sdev_contents);
        return (prof_lookup(dvp, nm, vpp, cred));
    }
    rw_exit(&parent->sdev_dotdot->sdev_contents);

    /* execute access is required to search the directory */
    if ((error = VOP_ACCESS(dvp, VEXEC, 0, cred, ct)) != 0) {
        return (error);
    }

    /* find existing name */
/* XXXci - We may need to translate the C-I flags on VOP_LOOKUP */
    error = VOP_LOOKUP(dvp, nm, &vp, NULL, 0, NULL, cred, ct, NULL, NULL);
    if (error == 0) {
        VN_RELE(vp);
        return (EEXIST);
    }
    if (error != ENOENT)
        return (error);

    /* require write access to create a directory */
    if ((error = VOP_ACCESS(dvp, VWRITE, 0, cred, ct)) != 0) {
        return (error);
    }

    /* put it into memory */
    rw_enter(&parent->sdev_contents, RW_WRITER);
    error = sdev_mknode(parent, nm, &self,
        va, NULL, NULL, cred, SDEV_READY);
    if (error) {
        rw_exit(&parent->sdev_contents);
        if (self)
            SDEV_RELE(self);
        return (error);
    }
    ASSERT(self && (self->sdev_state == SDEV_READY));
    rw_exit(&parent->sdev_contents);

    /* take care the timestamps for the node and its parent */
    sdev_update_timestamps(SDEVTOV(self), kcred,
        AT_CTIME|AT_MTIME|AT_ATIME);
    sdev_update_timestamps(dvp, kcred, AT_MTIME|AT_ATIME);
    if (SDEV_IS_GLOBAL(parent))
        atomic_inc_ulong(&parent->sdev_gdir_gen);

    /* wake up other threads blocked on looking up this node */
    mutex_enter(&self->sdev_lookup_lock);
    SDEV_UNBLOCK_OTHERS(self, SDEV_LOOKUP);
    mutex_exit(&self->sdev_lookup_lock);
    *vpp = SDEVTOV(self);
    return (0);
}

/*
 * allowing removing an empty directory under /dev
 */
/*ARGSUSED*/
static int
sdev_rmdir(struct vnode *dvp, char *nm, struct vnode *cdir, struct cred *cred,
    caller_context_t *ct, int flags)
{
    int error = 0;
    struct sdev_node *parent = (struct sdev_node *)VTOSDEV(dvp);
    struct sdev_node *self = NULL;
    struct vnode *vp = NULL;

    /* bail out early */
    if (strcmp(nm, ".") == 0)
        return (EINVAL);
    if (strcmp(nm, "..") == 0)
        return (EEXIST); /* should be ENOTEMPTY */

    /* no destruction of non-global node */
    ASSERT(parent && parent->sdev_dotdot);
    rw_enter(&parent->sdev_dotdot->sdev_contents, RW_READER);
    if (!SDEV_IS_GLOBAL(parent)) {
        rw_exit(&parent->sdev_dotdot->sdev_contents);
        return (ENOTSUP);
    }
    rw_exit(&parent->sdev_dotdot->sdev_contents);

    /* execute access is required to search the directory */
    if ((error = VOP_ACCESS(dvp, VEXEC, 0, cred, ct)) != 0)
        return (error);

    /* check existing name */
    rw_enter(&parent->sdev_contents, RW_WRITER);
    self = sdev_cache_lookup(parent, nm);
    if (self == NULL) {
        rw_exit(&parent->sdev_contents);
        return (ENOENT);
    }

    vp = SDEVTOV(self);
    if ((self->sdev_state == SDEV_INIT) ||
        (self->sdev_state == SDEV_ZOMBIE)) {
        rw_exit(&parent->sdev_contents);
        VN_RELE(vp);
        return (ENOENT);
    }

    /* write access is required to remove a directory */
    if ((error = VOP_ACCESS(dvp, VWRITE, 0, cred, ct)) != 0) {
        rw_exit(&parent->sdev_contents);
        VN_RELE(vp);
        return (error);
    }

    /* some sanity checks */
    if (vp == dvp || vp == cdir) {
        rw_exit(&parent->sdev_contents);
        VN_RELE(vp);
        return (EINVAL);
    }

    if (vp->v_type != VDIR) {
        rw_exit(&parent->sdev_contents);
        VN_RELE(vp);
        return (ENOTDIR);
    }

    if (vn_vfswlock(vp)) {
        rw_exit(&parent->sdev_contents);
        VN_RELE(vp);
        return (EBUSY);
    }

    if (vn_mountedvfs(vp) != NULL) {
        rw_exit(&parent->sdev_contents);
        vn_vfsunlock(vp);
        VN_RELE(vp);
        return (EBUSY);
    }

    self = VTOSDEV(vp);
    /* bail out on a non-empty directory */
    rw_enter(&self->sdev_contents, RW_READER);
    if (self->sdev_nlink > 2) {
        rw_exit(&self->sdev_contents);
        rw_exit(&parent->sdev_contents);
        vn_vfsunlock(vp);
        VN_RELE(vp);
        return (ENOTEMPTY);
    }
    rw_exit(&self->sdev_contents);

    /* unlink it from the directory cache */
    error = sdev_cache_update(parent, &self, nm, SDEV_CACHE_DELETE);
    rw_exit(&parent->sdev_contents);
    vn_vfsunlock(vp);

    if (error && (error != EBUSY)) {
        VN_RELE(vp);
    } else {
        sdcmn_err2(("sdev_rmdir: cleaning node %s from directory "
            " cache with error %d\n", nm, error));

        /* best effort to clean up the backing store */
        if (SDEV_IS_PERSIST(parent)) {
            ASSERT(parent->sdev_attrvp);
            error = VOP_RMDIR(parent->sdev_attrvp, nm,
                parent->sdev_attrvp, kcred, ct, flags);
            sdcmn_err2(("sdev_rmdir: cleaning device %s is on"
                " disk error %d\n", parent->sdev_path, error));
        }

        if (error == EBUSY)
            error = 0;
    }

    return (error);
}

/*
 * read the contents of a symbolic link
 */
static int
sdev_readlink(struct vnode *vp, struct uio *uiop, struct cred *cred,
    caller_context_t *ct)
{
    struct sdev_node *dv;
    int error = 0;

    ASSERT(vp->v_type == VLNK);

    dv = VTOSDEV(vp);

    if (dv->sdev_attrvp) {
        /* non-NULL attrvp implys a persisted node at READY state */
        return (VOP_READLINK(dv->sdev_attrvp, uiop, cred, ct));
    } else if (dv->sdev_symlink != NULL) {
        /* memory nodes, e.g. local nodes */
        rw_enter(&dv->sdev_contents, RW_READER);
        sdcmn_err2(("sdev_readlink link is %s\n", dv->sdev_symlink));
        error = uiomove(dv->sdev_symlink, strlen(dv->sdev_symlink),
            UIO_READ, uiop);
        rw_exit(&dv->sdev_contents);
        return (error);
    }

    return (ENOENT);
}

/*ARGSUSED4*/
static int
sdev_readdir(struct vnode *dvp, struct uio *uiop, struct cred *cred, int *eofp,
    caller_context_t *ct, int flags)
{
    struct sdev_node *parent = VTOSDEV(dvp);
    int error;

    /* execute access is required to search the directory */
    if ((error = VOP_ACCESS(dvp, VEXEC, 0, cred, ct)) != 0)
        return (error);

    ASSERT(parent);
    if (!SDEV_IS_GLOBAL(parent))
        prof_filldir(parent);
    return (devname_readdir_func(dvp, uiop, cred, eofp, SDEV_BROWSE));
}

/*ARGSUSED1*/
static void
sdev_inactive(struct vnode *vp, struct cred *cred, caller_context_t *ct)
{
    devname_inactive_func(vp, cred, NULL);
}

/*ARGSUSED2*/
static int
sdev_fid(struct vnode *vp, struct fid *fidp, caller_context_t *ct)
{
    struct sdev_node    *dv = VTOSDEV(vp);
    struct sdev_fid *sdev_fid;

    if (fidp->fid_len < (sizeof (struct sdev_fid) - sizeof (ushort_t))) {
        fidp->fid_len = sizeof (struct sdev_fid) - sizeof (ushort_t);
        return (ENOSPC);
    }

    sdev_fid = (struct sdev_fid *)fidp;
    bzero(sdev_fid, sizeof (struct sdev_fid));
    sdev_fid->sdevfid_len =
        (int)sizeof (struct sdev_fid) - sizeof (ushort_t);
    sdev_fid->sdevfid_ino = dv->sdev_ino;

    return (0);
}

/*
 * This pair of routines bracket all VOP_READ, VOP_WRITE
 * and VOP_READDIR requests.  The contents lock stops things
 * moving around while we're looking at them.
 */
/*ARGSUSED2*/
static int
sdev_rwlock(struct vnode *vp, int write_flag, caller_context_t *ctp)
{
    rw_enter(&VTOSDEV(vp)->sdev_contents,
        write_flag ? RW_WRITER : RW_READER);
    return (write_flag ? V_WRITELOCK_TRUE : V_WRITELOCK_FALSE);
}

/*ARGSUSED1*/
static void
sdev_rwunlock(struct vnode *vp, int write_flag, caller_context_t *ctp)
{
    rw_exit(&VTOSDEV(vp)->sdev_contents);
}

/*ARGSUSED1*/
static int
sdev_seek(struct vnode *vp, offset_t ooff, offset_t *noffp,
    caller_context_t *ct)
{
    struct vnode *attrvp = VTOSDEV(vp)->sdev_attrvp;

    ASSERT(vp->v_type != VCHR &&
        vp->v_type != VBLK && vp->v_type != VLNK);

    if (vp->v_type == VDIR)
        return (fs_seek(vp, ooff, noffp, ct));

    ASSERT(attrvp);
    return (VOP_SEEK(attrvp, ooff, noffp, ct));
}

/*ARGSUSED1*/
static int
sdev_frlock(struct vnode *vp, int cmd, struct flock64 *bfp, int flag,
    offset_t offset, struct flk_callback *flk_cbp, struct cred *cr,
    caller_context_t *ct)
{
    int error;
    struct sdev_node *dv = VTOSDEV(vp);

    ASSERT(dv);
    ASSERT(dv->sdev_attrvp);
    error = VOP_FRLOCK(dv->sdev_attrvp, cmd, bfp, flag, offset,
        flk_cbp, cr, ct);

    return (error);
}

static int
sdev_setfl(struct vnode *vp, int oflags, int nflags, cred_t *cr,
    caller_context_t *ct)
{
    struct sdev_node *dv = VTOSDEV(vp);
    ASSERT(dv);
    ASSERT(dv->sdev_attrvp);

    return (VOP_SETFL(dv->sdev_attrvp, oflags, nflags, cr, ct));
}

static int
sdev_pathconf(vnode_t *vp, int cmd, ulong_t *valp, cred_t *cr,
    caller_context_t *ct)
{
    switch (cmd) {
    case _PC_ACL_ENABLED:
        *valp = SDEV_ACL_FLAVOR(vp);
        return (0);
    }

    return (fs_pathconf(vp, cmd, valp, cr, ct));
}

vnodeops_t *sdev_vnodeops;

const fs_operation_def_t sdev_vnodeops_tbl[] = {
    VOPNAME_OPEN,       { .vop_open = sdev_open },
    VOPNAME_CLOSE,      { .vop_close = sdev_close },
    VOPNAME_READ,       { .vop_read = sdev_read },
    VOPNAME_WRITE,      { .vop_write = sdev_write },
    VOPNAME_IOCTL,      { .vop_ioctl = sdev_ioctl },
    VOPNAME_GETATTR,    { .vop_getattr = sdev_getattr },
    VOPNAME_SETATTR,    { .vop_setattr = sdev_setattr },
    VOPNAME_ACCESS,     { .vop_access = sdev_access },
    VOPNAME_LOOKUP,     { .vop_lookup = sdev_lookup },
    VOPNAME_CREATE,     { .vop_create = sdev_create },
    VOPNAME_RENAME,     { .vop_rename = sdev_rename },
    VOPNAME_REMOVE,     { .vop_remove = sdev_remove },
    VOPNAME_MKDIR,      { .vop_mkdir = sdev_mkdir },
    VOPNAME_RMDIR,      { .vop_rmdir = sdev_rmdir },
    VOPNAME_READDIR,    { .vop_readdir = sdev_readdir },
    VOPNAME_SYMLINK,    { .vop_symlink = sdev_symlink },
    VOPNAME_READLINK,   { .vop_readlink = sdev_readlink },
    VOPNAME_INACTIVE,   { .vop_inactive = sdev_inactive },
    VOPNAME_FID,        { .vop_fid = sdev_fid },
    VOPNAME_RWLOCK,     { .vop_rwlock = sdev_rwlock },
    VOPNAME_RWUNLOCK,   { .vop_rwunlock = sdev_rwunlock },
    VOPNAME_SEEK,       { .vop_seek = sdev_seek },
    VOPNAME_FRLOCK,     { .vop_frlock = sdev_frlock },
    VOPNAME_PATHCONF,   { .vop_pathconf = sdev_pathconf },
    VOPNAME_SETFL,      { .vop_setfl = sdev_setfl },
    VOPNAME_SETSECATTR, { .vop_setsecattr = sdev_setsecattr },
    VOPNAME_GETSECATTR, { .vop_getsecattr = sdev_getsecattr },
    NULL,           NULL
};

int sdev_vnodeops_tbl_size = sizeof (sdev_vnodeops_tbl);