remove unnecessary offset_t casts of 0

[unleashed.git] / kernel / fs / specfs / specvnops.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 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 * Copyright 2015 Nexenta Systems, Inc.  All rights reserved.
 * Copyright (c) 2017 by Delphix. All rights reserved.
 */

/*      Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T     */
/*        All Rights Reserved   */

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */

#include <sys/types.h>
#include <sys/thread.h>
#include <sys/t_lock.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bitmap.h>
#include <sys/buf.h>
#include <sys/cmn_err.h>
#include <sys/conf.h>
#include <sys/ddi.h>
#include <sys/debug.h>
#include <sys/dkio.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/fcntl.h>
#include <sys/flock.h>
#include <sys/file.h>
#include <sys/kmem.h>
#include <sys/mman.h>
#include <sys/open.h>
#include <sys/swap.h>
#include <sys/sysmacros.h>
#include <sys/uio.h>
#include <sys/vfs.h>
#include <sys/vnode.h>
#include <sys/stat.h>
#include <sys/poll.h>
#include <sys/stream.h>
#include <sys/strsubr.h>
#include <sys/policy.h>
#include <sys/devpolicy.h>

#include <sys/proc.h>
#include <sys/user.h>
#include <sys/session.h>
#include <sys/vmsystm.h>
#include <sys/vtrace.h>
#include <sys/pathname.h>

#include <sys/fs/snode.h>

#include <vm/seg.h>
#include <vm/seg_map.h>
#include <vm/page.h>
#include <vm/pvn.h>
#include <vm/seg_dev.h>
#include <vm/seg_vn.h>

#include <sys/fs_subr.h>

#include <sys/esunddi.h>
#include <sys/autoconf.h>
#include <sys/sunndi.h>
#include <sys/contract/device_impl.h>


static int spec_open(struct vnode **, int, struct cred *, caller_context_t *);
static int spec_close(struct vnode *, int, int, offset_t, struct cred *,
        caller_context_t *);
static int spec_read(struct vnode *, struct uio *, int, struct cred *,
        caller_context_t *);
static int spec_write(struct vnode *, struct uio *, int, struct cred *,
        caller_context_t *);
static int spec_ioctl(struct vnode *, int, intptr_t, int, struct cred *, int *,
        caller_context_t *);
static int spec_getattr(struct vnode *, struct vattr *, int, struct cred *,
        caller_context_t *);
static int spec_setattr(struct vnode *, struct vattr *, int, struct cred *,
        caller_context_t *);
static int spec_access(struct vnode *, int, int, struct cred *,
        caller_context_t *);
static int spec_create(struct vnode *, char *, vattr_t *, enum vcexcl, int,
        struct vnode **, struct cred *, int, caller_context_t *, vsecattr_t *);
static int spec_fsync(struct vnode *, int, struct cred *, caller_context_t *);
static void spec_inactive(struct vnode *, struct cred *, caller_context_t *);
static int spec_fid(struct vnode *, struct fid *, caller_context_t *);
static int spec_seek(struct vnode *, offset_t, offset_t *, caller_context_t *);
static int spec_frlock(struct vnode *, int, struct flock64 *, int, offset_t,
        struct flk_callback *, struct cred *, caller_context_t *);
static int spec_realvp(struct vnode *, struct vnode **, caller_context_t *);

static int spec_getpage(struct vnode *, offset_t, size_t, uint_t *, page_t **,
        size_t, struct seg *, caddr_t, enum seg_rw, struct cred *,
        caller_context_t *);
static int spec_putapage(struct vnode *, page_t *, uoff_t *, size_t *, int,
        struct cred *);
static struct buf *spec_startio(struct vnode *, page_t *, uoff_t, size_t,
        int);
static int spec_getapage(struct vnode *, uoff_t, size_t, uint_t *,
        page_t **, size_t, struct seg *, caddr_t, enum seg_rw, struct cred *);
static int spec_map(struct vnode *, offset_t, struct as *, caddr_t *, size_t,
        uchar_t, uchar_t, uint_t, struct cred *, caller_context_t *);
static int spec_addmap(struct vnode *, offset_t, struct as *, caddr_t, size_t,
        uchar_t, uchar_t, uint_t, struct cred *, caller_context_t *);
static int spec_delmap(struct vnode *, offset_t, struct as *, caddr_t, size_t,
        uint_t, uint_t, uint_t, struct cred *, caller_context_t *);

static int spec_poll(struct vnode *, short, int, short *, struct pollhead **,
        caller_context_t *);
static int spec_dump(struct vnode *, caddr_t, offset_t, offset_t,
    caller_context_t *);
static int spec_pageio(struct vnode *, page_t *, uoff_t, size_t, int,
    cred_t *, caller_context_t *);

static int spec_getsecattr(struct vnode *, vsecattr_t *, int, struct cred *,
        caller_context_t *);
static int spec_setsecattr(struct vnode *, vsecattr_t *, int, struct cred *,
        caller_context_t *);
static int spec_pathconf(struct vnode *, int, ulong_t *, struct cred *,
        caller_context_t *);

#define SN_HOLD(csp)    { \
        mutex_enter(&csp->s_lock); \
        csp->s_count++; \
        mutex_exit(&csp->s_lock); \
}

#define SN_RELE(csp)    { \
        mutex_enter(&csp->s_lock); \
        csp->s_count--; \
        ASSERT((csp->s_count > 0) || (csp->s_vnode->v_stream == NULL)); \
        mutex_exit(&csp->s_lock); \
}

#define S_ISFENCED(sp)  ((VTOS((sp)->s_commonvp))->s_flag & SFENCED)

/*
 * *PLEASE NOTE*: If you add new entry points to specfs, do
 * not forget to add support for fencing. A fenced snode
 * is indicated by the SFENCED flag in the common snode.
 * If a snode is fenced, determine if your entry point is
 * a configuration operation (Example: open), a detection
 * operation (Example: gettattr), an I/O operation (Example: ioctl())
 * or an unconfiguration operation (Example: close). If it is
 * a configuration or detection operation, fail the operation
 * for a fenced snode with an ENXIO or EIO as appropriate. If
 * it is any other operation, let it through.
 */

const struct vnodeops spec_vnodeops = {
        .vnop_name = "specfs",
        .vop_open = spec_open,
        .vop_close = spec_close,
        .vop_read = spec_read,
        .vop_write = spec_write,
        .vop_ioctl = spec_ioctl,
        .vop_getattr = spec_getattr,
        .vop_setattr = spec_setattr,
        .vop_access = spec_access,
        .vop_create = spec_create,
        .vop_fsync = spec_fsync,
        .vop_inactive = spec_inactive,
        .vop_fid = spec_fid,
        .vop_seek = spec_seek,
        .vop_pathconf = spec_pathconf,
        .vop_frlock = spec_frlock,
        .vop_realvp = spec_realvp,
        .vop_getpage = spec_getpage,
        .vop_putpage = spec_putpage,
        .vop_map = spec_map,
        .vop_addmap = spec_addmap,
        .vop_delmap = spec_delmap,
        .vop_poll = spec_poll,
        .vop_dump = spec_dump,
        .vop_pageio = spec_pageio,
        .vop_setsecattr = spec_setsecattr,
        .vop_getsecattr = spec_getsecattr,
};

/*
 * Return address of spec_vnodeops
 */
const struct vnodeops *
spec_getvnodeops(void)
{
        return (&spec_vnodeops);
}

extern vnode_t *rconsvp;

/*
 * Acquire the serial lock on the common snode.
 */
#define LOCK_CSP(csp)                   (void) spec_lockcsp(csp, 0, 1, 0)
#define LOCKHOLD_CSP_SIG(csp)           spec_lockcsp(csp, 1, 1, 1)
#define SYNCHOLD_CSP_SIG(csp, intr)     spec_lockcsp(csp, intr, 0, 1)

typedef enum {
        LOOP,
        INTR,
        SUCCESS
} slock_ret_t;

/*
 * Synchronize with active SLOCKED snode, optionally checking for a signal and
 * optionally returning with SLOCKED set and SN_HOLD done.  The 'intr'
 * argument determines if the thread is interruptible by a signal while
 * waiting, the function returns INTR if interrupted while there is another
 * thread closing this snonde and LOOP if interrupted otherwise.
 * When SUCCESS is returned the 'hold' argument determines if the open
 * count (SN_HOLD) has been incremented and the 'setlock' argument
 * determines if the function returns with SLOCKED set.
 */
static slock_ret_t
spec_lockcsp(struct snode *csp, int intr, int setlock, int hold)
{
        slock_ret_t ret = SUCCESS;
        mutex_enter(&csp->s_lock);
        while (csp->s_flag & SLOCKED) {
                csp->s_flag |= SWANT;
                if (intr) {
                        if (!cv_wait_sig(&csp->s_cv, &csp->s_lock)) {
                                if (csp->s_flag & SCLOSING)
                                        ret = INTR;
                                else
                                        ret = LOOP;
                                mutex_exit(&csp->s_lock);
                                return (ret);           /* interrupted */
                        }
                } else {
                        cv_wait(&csp->s_cv, &csp->s_lock);
                }
        }
        if (setlock)
                csp->s_flag |= SLOCKED;
        if (hold)
                csp->s_count++;         /* one more open reference : SN_HOLD */
        mutex_exit(&csp->s_lock);
        return (ret);                   /* serialized/locked */
}

/*
 * Unlock the serial lock on the common snode
 */
#define UNLOCK_CSP_LOCK_HELD(csp)                       \
        ASSERT(mutex_owned(&csp->s_lock));              \
        if (csp->s_flag & SWANT)                        \
                cv_broadcast(&csp->s_cv);               \
        csp->s_flag &= ~(SWANT|SLOCKED);

#define UNLOCK_CSP(csp)                                 \
        mutex_enter(&csp->s_lock);                      \
        UNLOCK_CSP_LOCK_HELD(csp);                      \
        mutex_exit(&csp->s_lock);

/*
 * compute/return the size of the device
 */
#define SPEC_SIZE(csp)  \
        (((csp)->s_flag & SSIZEVALID) ? (csp)->s_size : spec_size(csp))

/*
 * Compute and return the size.  If the size in the common snode is valid then
 * return it.  If not valid then get the size from the driver and set size in
 * the common snode.  If the device has not been attached then we don't ask for
 * an update from the driver- for non-streams SSIZEVALID stays unset until the
 * device is attached. A stat of a mknod outside /devices (non-devfs) may
 * report UNKNOWN_SIZE because the device may not be attached yet (SDIPSET not
 * established in mknod until open time). An stat in /devices will report the
 * size correctly.  Specfs should always call SPEC_SIZE instead of referring
 * directly to s_size to initialize/retrieve the size of a device.
 *
 * XXX There is an inconsistency between block and raw - "unknown" is
 * UNKNOWN_SIZE for VBLK and 0 for VCHR(raw).
 */
static uoff_t
spec_size(struct snode *csp)
{
        struct vnode    *cvp = STOV(csp);
        uoff_t  size;
        int             plen;
        uint32_t        size32;
        dev_t           dev;
        dev_info_t      *devi;
        major_t         maj;
        uint_t          blksize;
        int             blkshift;

        ASSERT((csp)->s_commonvp == cvp);       /* must be common node */

        /* return cached value */
        mutex_enter(&csp->s_lock);
        if (csp->s_flag & SSIZEVALID) {
                mutex_exit(&csp->s_lock);
                return (csp->s_size);
        }

        /* fop_getattr of mknod has not had devcnt restriction applied */
        dev = cvp->v_rdev;
        maj = getmajor(dev);
        if (maj >= devcnt) {
                /* return non-cached UNKNOWN_SIZE */
                mutex_exit(&csp->s_lock);
                return ((cvp->v_type == VCHR) ? 0 : UNKNOWN_SIZE);
        }

        /* establish cached zero size for streams */
        if (STREAMSTAB(maj)) {
                csp->s_size = 0;
                csp->s_flag |= SSIZEVALID;
                mutex_exit(&csp->s_lock);
                return (0);
        }

        /*
         * Return non-cached UNKNOWN_SIZE if not open.
         *
         * NB: This check is bogus, calling prop_op(9E) should be gated by
         * attach, not open. Not having this check however opens up a new
         * context under which a driver's prop_op(9E) could be called. Calling
         * prop_op(9E) in this new context has been shown to expose latent
         * driver bugs (insufficient NULL pointer checks that lead to panic).
         * We are keeping this open check for now to avoid these panics.
         */
        if (csp->s_count == 0) {
                mutex_exit(&csp->s_lock);
                return ((cvp->v_type == VCHR) ? 0 : UNKNOWN_SIZE);
        }

        /* Return non-cached UNKNOWN_SIZE if not attached. */
        if (((csp->s_flag & SDIPSET) == 0) || (csp->s_dip == NULL) ||
            !i_ddi_devi_attached(csp->s_dip)) {
                mutex_exit(&csp->s_lock);
                return ((cvp->v_type == VCHR) ? 0 : UNKNOWN_SIZE);
        }

        devi = csp->s_dip;

        /*
         * Established cached size obtained from the attached driver. Since we
         * know the devinfo node, for efficiency we use cdev_prop_op directly
         * instead of [cb]dev_[Ss]size.
         */
        if (cvp->v_type == VCHR) {
                size = 0;
                plen = sizeof (size);
                if (cdev_prop_op(dev, devi, PROP_LEN_AND_VAL_BUF,
                    DDI_PROP_NOTPROM | DDI_PROP_DONTPASS |
                    DDI_PROP_CONSUMER_TYPED, "Size", (caddr_t)&size,
                    &plen) != DDI_PROP_SUCCESS) {
                        plen = sizeof (size32);
                        if (cdev_prop_op(dev, devi, PROP_LEN_AND_VAL_BUF,
                            DDI_PROP_NOTPROM | DDI_PROP_DONTPASS,
                            "size", (caddr_t)&size32, &plen) ==
                            DDI_PROP_SUCCESS)
                                size = size32;
                }
        } else {
                size = UNKNOWN_SIZE;
                plen = sizeof (size);
                if (cdev_prop_op(dev, devi, PROP_LEN_AND_VAL_BUF,
                    DDI_PROP_NOTPROM | DDI_PROP_DONTPASS |
                    DDI_PROP_CONSUMER_TYPED, "Nblocks", (caddr_t)&size,
                    &plen) != DDI_PROP_SUCCESS) {
                        plen = sizeof (size32);
                        if (cdev_prop_op(dev, devi, PROP_LEN_AND_VAL_BUF,
                            DDI_PROP_NOTPROM | DDI_PROP_DONTPASS,
                            "nblocks", (caddr_t)&size32, &plen) ==
                            DDI_PROP_SUCCESS)
                                size = size32;
                }

                if (size != UNKNOWN_SIZE) {
                        blksize = DEV_BSIZE;            /* default */
                        plen = sizeof (blksize);

                        /* try to get dev_t specific "blksize" */
                        if (cdev_prop_op(dev, devi, PROP_LEN_AND_VAL_BUF,
                            DDI_PROP_NOTPROM | DDI_PROP_DONTPASS,
                            "blksize", (caddr_t)&blksize, &plen) !=
                            DDI_PROP_SUCCESS) {
                                /*
                                 * Try for dev_info node "device-blksize".
                                 * If this fails then blksize will still be
                                 * DEV_BSIZE default value.
                                 */
                                (void) cdev_prop_op(DDI_DEV_T_ANY, devi,
                                    PROP_LEN_AND_VAL_BUF,
                                    DDI_PROP_NOTPROM | DDI_PROP_DONTPASS,
                                    "device-blksize", (caddr_t)&blksize, &plen);
                        }

                        /* blksize must be a power of two */
                        ASSERT(BIT_ONLYONESET(blksize));
                        blkshift = highbit(blksize) - 1;

                        /* convert from block size to byte size */
                        if (size < (MAXOFFSET_T >> blkshift))
                                size = size << blkshift;
                        else
                                size = UNKNOWN_SIZE;
                }
        }

        csp->s_size = size;
        csp->s_flag |= SSIZEVALID;

        mutex_exit(&csp->s_lock);
        return (size);
}

/*
 * This function deal with vnode substitution in the case of
 * device cloning.
 */
static int
spec_clone(struct vnode **vpp, dev_t newdev, int vtype, struct stdata *stp)
{
        dev_t           dev = (*vpp)->v_rdev;
        major_t         maj = getmajor(dev);
        major_t         newmaj = getmajor(newdev);
        int             sysclone = (maj == clone_major);
        int             qassociate_used = 0;
        struct snode    *oldsp, *oldcsp;
        struct snode    *newsp, *newcsp;
        struct vnode    *newvp, *newcvp;
        dev_info_t      *dip;
        queue_t         *dq;

        ASSERT(dev != newdev);

        /*
         * Check for cloning across different drivers.
         * We only support this under the system provided clone driver
         */
        if ((maj != newmaj) && !sysclone) {
                cmn_err(CE_NOTE,
                    "unsupported clone open maj = %u, newmaj = %u",
                    maj, newmaj);
                return (ENXIO);
        }

        /* old */
        oldsp = VTOS(*vpp);
        oldcsp = VTOS(oldsp->s_commonvp);

        /* new */
        newvp = makespecvp(newdev, vtype);
        ASSERT(newvp != NULL);
        newsp = VTOS(newvp);
        newcvp = newsp->s_commonvp;
        newcsp = VTOS(newcvp);

        /*
         * Clones inherit fsid, realvp, and dip.
         * XXX realvp inherit is not occurring, does fstat of clone work?
         */
        newsp->s_fsid = oldsp->s_fsid;
        if (sysclone) {
                newsp->s_flag |= SCLONE;
                dip = NULL;
        } else {
                newsp->s_flag |= SSELFCLONE;
                dip = oldcsp->s_dip;
        }

        /*
         * If we cloned to an opened newdev that already has called
         * spec_assoc_vp_with_devi (SDIPSET set) then the association is
         * already established.
         */
        if (!(newcsp->s_flag & SDIPSET)) {
                /*
                 * Establish s_dip association for newdev.
                 *
                 * If we trusted the getinfo(9E) DDI_INFO_DEVT2INSTANCE
                 * implementation of all cloning drivers  (SCLONE and SELFCLONE)
                 * we would always use e_ddi_hold_devi_by_dev().  We know that
                 * many drivers have had (still have?) problems with
                 * DDI_INFO_DEVT2INSTANCE, so we try to minimize reliance by
                 * detecting drivers that use QASSOCIATE (by looking down the
                 * stream) and setting their s_dip association to NULL.
                 */
                qassociate_used = 0;
                if (stp) {
                        for (dq = stp->sd_wrq; dq; dq = dq->q_next) {
                                if (_RD(dq)->q_flag & _QASSOCIATED) {
                                        qassociate_used = 1;
                                        dip = NULL;
                                        break;
                                }
                        }
                }

                if (dip || qassociate_used) {
                        spec_assoc_vp_with_devi(newvp, dip);
                } else {
                        /* derive association from newdev */
                        dip = e_ddi_hold_devi_by_dev(newdev, 0);
                        spec_assoc_vp_with_devi(newvp, dip);
                        if (dip)
                                ddi_release_devi(dip);
                }
        }

        SN_HOLD(newcsp);

        /* deal with stream stuff */
        if (stp != NULL) {
                LOCK_CSP(newcsp);       /* synchronize stream open/close */
                mutex_enter(&newcsp->s_lock);
                newcvp->v_stream = newvp->v_stream = stp;
                stp->sd_vnode = newcvp;
                stp->sd_strtab = STREAMSTAB(newmaj);
                mutex_exit(&newcsp->s_lock);
                UNLOCK_CSP(newcsp);
        }

        /* substitute the vnode */
        SN_RELE(oldcsp);
        VN_RELE(*vpp);
        *vpp = newvp;

        return (0);
}

static int
spec_open(struct vnode **vpp, int flag, struct cred *cr, caller_context_t *cc)
{
        major_t maj;
        dev_t dev, newdev;
        struct vnode *vp, *cvp;
        struct snode *sp, *csp;
        struct stdata *stp;
        dev_info_t *dip;
        int error, type;
        contract_t *ct = NULL;
        int open_returns_eintr;
        slock_ret_t spec_locksp_ret;


        flag &= ~FCREAT;                /* paranoia */

        vp = *vpp;
        sp = VTOS(vp);
        ASSERT((vp->v_type == VCHR) || (vp->v_type == VBLK));
        if ((vp->v_type != VCHR) && (vp->v_type != VBLK))
                return (ENXIO);

        /*
         * If the VFS_NODEVICES bit was set for the mount,
         * do not allow opens of special devices.
         */
        if (sp->s_realvp && (sp->s_realvp->v_vfsp->vfs_flag & VFS_NODEVICES))
                return (ENXIO);

        newdev = dev = vp->v_rdev;

        /*
         * If we are opening a node that has not had spec_assoc_vp_with_devi
         * called against it (mknod outside /devices or a non-dacf makespecvp
         * node) then SDIPSET will not be set. In this case we call an
         * interface which will reconstruct the path and lookup (drive attach)
         * through devfs (e_ddi_hold_devi_by_dev -> e_ddi_hold_devi_by_path ->
         * devfs_lookupname).  For support of broken drivers that don't call
         * ddi_create_minor_node for all minor nodes in their instance space,
         * we call interfaces that operates at the directory/devinfo
         * (major/instance) level instead of to the leaf/minor node level.
         * After finding and attaching the dip we associate it with the
         * common specfs vnode (s_dip), which sets SDIPSET.  A DL_DETACH_REQ
         * to style-2 stream driver may set s_dip to NULL with SDIPSET set.
         *
         * NOTE: Although e_ddi_hold_devi_by_dev takes a dev_t argument, its
         * implementation operates at the major/instance level since it only
         * need to return a dip.
         */
        cvp = sp->s_commonvp;
        csp = VTOS(cvp);
        if (!(csp->s_flag & SDIPSET)) {
                /* try to attach, return error if we fail */
                if ((dip = e_ddi_hold_devi_by_dev(dev, 0)) == NULL)
                        return (ENXIO);

                /* associate dip with the common snode s_dip */
                spec_assoc_vp_with_devi(vp, dip);
                ddi_release_devi(dip);  /* from e_ddi_hold_devi_by_dev */
        }

        /* check if device fenced off */
        if (S_ISFENCED(sp))
                return (ENXIO);

#ifdef  DEBUG
        /* verify attach/open exclusion guarantee */
        dip = csp->s_dip;
        ASSERT((dip == NULL) || i_ddi_devi_attached(dip));
#endif  /* DEBUG */

        if ((error = secpolicy_spec_open(cr, vp, flag)) != 0)
                return (error);

        /* Verify existance of open(9E) implementation. */
        maj = getmajor(dev);
        if ((maj >= devcnt) ||
            (devopsp[maj]->devo_cb_ops == NULL) ||
            (devopsp[maj]->devo_cb_ops->cb_open == NULL))
                return (ENXIO);

        /*
         * split STREAMS vs. non-STREAMS
         *
         * If the device is a dual-personality device, then we might want
         * to allow for a regular OTYP_BLK open.  If however it's strictly
         * a pure STREAMS device, the cb_open entry point will be
         * nodev() which returns ENXIO.  This does make this failure path
         * somewhat longer, but such attempts to use OTYP_BLK with STREAMS
         * devices should be exceedingly rare.  (Most of the time they will
         * be due to programmer error.)
         */
        if ((vp->v_type == VCHR) && (STREAMSTAB(maj)))
                goto streams_open;

not_streams:
        /*
         * Wait for in progress last close to complete. This guarantees
         * to the driver writer that we will never be in the drivers
         * open and close on the same (dev_t, otype) at the same time.
         * Open count already incremented (SN_HOLD) on non-zero return.
         * The wait is interruptible by a signal if the driver sets the
         * D_OPEN_RETURNS_EINTR cb_ops(9S) cb_flag or sets the
         * ddi-open-returns-eintr(9P) property in its driver.conf.
         */
        if ((devopsp[maj]->devo_cb_ops->cb_flag & D_OPEN_RETURNS_EINTR) ||
            (devnamesp[maj].dn_flags & DN_OPEN_RETURNS_EINTR))
                open_returns_eintr = 1;
        else
                open_returns_eintr = 0;
        while ((spec_locksp_ret = SYNCHOLD_CSP_SIG(csp, open_returns_eintr)) !=
            SUCCESS) {
                if (spec_locksp_ret == INTR)
                        return (EINTR);
        }

        /* non streams open */
        type = (vp->v_type == VBLK ? OTYP_BLK : OTYP_CHR);
        error = dev_open(&newdev, flag, type, cr);

        /* deal with clone case */
        if (error == 0 && dev != newdev) {
                error = spec_clone(vpp, newdev, vp->v_type, NULL);
                /*
                 * bail on clone failure, further processing
                 * results in undefined behaviors.
                 */
                if (error != 0)
                        return (error);
                sp = VTOS(*vpp);
                csp = VTOS(sp->s_commonvp);
        }

        /*
         * create contracts only for userland opens
         * Successful open and cloning is done at this point.
         */
        if (error == 0 && !(flag & FKLYR)) {
                int spec_type;
                spec_type = (STOV(csp)->v_type == VCHR) ? S_IFCHR : S_IFBLK;
                if (contract_device_open(newdev, spec_type, NULL) != 0) {
                        error = EIO;
                }
        }

        if (error == 0) {
                sp->s_size = SPEC_SIZE(csp);

                if ((csp->s_flag & SNEEDCLOSE) == 0) {
                        int nmaj = getmajor(newdev);
                        mutex_enter(&csp->s_lock);
                        /* successful open needs a close later */
                        csp->s_flag |= SNEEDCLOSE;

                        /*
                         * Invalidate possible cached "unknown" size
                         * established by a fop_getattr while open was in
                         * progress, and the driver might fail prop_op(9E).
                         */
                        if (((cvp->v_type == VCHR) && (csp->s_size == 0)) ||
                            ((cvp->v_type == VBLK) &&
                            (csp->s_size == UNKNOWN_SIZE)))
                                csp->s_flag &= ~SSIZEVALID;

                        if (devopsp[nmaj]->devo_cb_ops->cb_flag & D_64BIT)
                                csp->s_flag |= SLOFFSET;
                        if (devopsp[nmaj]->devo_cb_ops->cb_flag & D_U64BIT)
                                csp->s_flag |= SLOFFSET | SANYOFFSET;
                        mutex_exit(&csp->s_lock);
                }
                return (0);
        }

        /*
         * Open failed. If we missed a close operation because
         * we were trying to get the device open and it is the
         * last in progress open that is failing then call close.
         *
         * NOTE: Only non-streams open has this race condition.
         */
        mutex_enter(&csp->s_lock);
        csp->s_count--;                 /* decrement open count : SN_RELE */
        if ((csp->s_count == 0) &&      /* no outstanding open */
            (csp->s_mapcnt == 0) &&     /* no mapping */
            (csp->s_flag & SNEEDCLOSE)) { /* need a close */
                csp->s_flag &= ~(SNEEDCLOSE | SSIZEVALID);

                /* See comment in spec_close() */
                if (csp->s_flag & (SCLONE | SSELFCLONE))
                        csp->s_flag &= ~SDIPSET;

                csp->s_flag |= SCLOSING;
                mutex_exit(&csp->s_lock);

                ASSERT(*vpp != NULL);
                (void) device_close(*vpp, flag, cr);

                mutex_enter(&csp->s_lock);
                csp->s_flag &= ~SCLOSING;
                mutex_exit(&csp->s_lock);
        } else {
                mutex_exit(&csp->s_lock);
        }
        return (error);

streams_open:
        /*
         * Lock common snode to prevent any new clone opens on this
         * stream while one is in progress. This is necessary since
         * the stream currently associated with the clone device will
         * not be part of it after the clone open completes. Unfortunately
         * we don't know in advance if this is a clone
         * device so we have to lock all opens.
         *
         * If we fail, it's because of an interrupt - EINTR return is an
         * expected aspect of opening a stream so we don't need to check
         * D_OPEN_RETURNS_EINTR. Open count already incremented (SN_HOLD)
         * on non-zero return.
         */
        if (LOCKHOLD_CSP_SIG(csp) != SUCCESS)
                return (EINTR);

        error = stropen(cvp, &newdev, flag, cr);
        stp = cvp->v_stream;

        /* deal with the clone case */
        if ((error == 0) && (dev != newdev)) {
                vp->v_stream = cvp->v_stream = NULL;
                UNLOCK_CSP(csp);
                error = spec_clone(vpp, newdev, vp->v_type, stp);
                /*
                 * bail on clone failure, further processing
                 * results in undefined behaviors.
                 */
                if (error != 0)
                        return (error);
                sp = VTOS(*vpp);
                csp = VTOS(sp->s_commonvp);
        } else if (error == 0) {
                vp->v_stream = stp;
                UNLOCK_CSP(csp);
        }

        /*
         * create contracts only for userland opens
         * Successful open and cloning is done at this point.
         */
        if (error == 0 && !(flag & FKLYR)) {
                /* STREAM is of type S_IFCHR */
                if (contract_device_open(newdev, S_IFCHR, &ct) != 0) {
                        UNLOCK_CSP(csp);
                        (void) spec_close(vp, flag, 1, 0, cr, cc);
                        return (EIO);
                }
        }

        if (error == 0) {
                /* STREAMS devices don't have a size */
                sp->s_size = csp->s_size = 0;

                if (!(stp->sd_flag & STRISTTY) || (flag & FNOCTTY))
                        return (0);

                /* try to allocate it as a controlling terminal */
                if (strctty(stp) != EINTR)
                        return (0);

                /* strctty() was interrupted by a signal */
                if (ct) {
                        /* we only create contracts for userland opens */
                        ASSERT(ttoproc(curthread));
                        (void) contract_abandon(ct, ttoproc(curthread), 0);
                }
                (void) spec_close(vp, flag, 1, 0, cr, cc);
                return (EINTR);
        }

        /*
         * Deal with stropen failure.
         *
         * sd_flag in the stream head cannot change since the
         * common snode is locked before the call to stropen().
         */
        if ((stp != NULL) && (stp->sd_flag & STREOPENFAIL)) {
                /*
                 * Open failed part way through.
                 */
                mutex_enter(&stp->sd_lock);
                stp->sd_flag &= ~STREOPENFAIL;
                mutex_exit(&stp->sd_lock);

                UNLOCK_CSP(csp);
                (void) spec_close(vp, flag, 1, 0, cr, cc);
        } else {
                UNLOCK_CSP(csp);
                SN_RELE(csp);
        }

        /*
         * Resolution for STREAMS vs. regular character device: If the
         * STREAMS open(9e) returns ENOSTR, then try an ordinary device
         * open instead.
         */
        if (error == ENOSTR) {
                goto not_streams;
        }
        return (error);
}

/*ARGSUSED2*/
static int
spec_close(
        struct vnode    *vp,
        int             flag,
        int             count,
        offset_t        offset,
        struct cred     *cr,
        caller_context_t *ct)
{
        struct vnode *cvp;
        struct snode *sp, *csp;
        enum vtype type;
        dev_t dev;
        int error = 0;
        int sysclone;

        if (!(flag & FKLYR)) {
                /* this only applies to closes of devices from userland */
                cleanlocks(vp, ttoproc(curthread)->p_pid, 0);
                cleanshares(vp, ttoproc(curthread)->p_pid);
                if (vp->v_stream)
                        strclean(vp);
        }
        if (count > 1)
                return (0);

        /* we allow close to succeed even if device is fenced off */
        sp = VTOS(vp);
        cvp = sp->s_commonvp;

        dev = sp->s_dev;
        type = vp->v_type;

        ASSERT(type == VCHR || type == VBLK);

        /*
         * Prevent close/close and close/open races by serializing closes
         * on this common snode. Clone opens are held up until after
         * we have closed this device so the streams linkage is maintained
         */
        csp = VTOS(cvp);

        LOCK_CSP(csp);
        mutex_enter(&csp->s_lock);

        csp->s_count--;                 /* one fewer open reference : SN_RELE */
        sysclone = sp->s_flag & SCLONE;

        /*
         * Invalidate size on each close.
         *
         * XXX We do this on each close because we don't have interfaces that
         * allow a driver to invalidate the size.  Since clearing this on each
         * close this causes property overhead we skip /dev/null and
         * /dev/zero to avoid degrading kenbus performance.
         */
        if (getmajor(dev) != mm_major)
                csp->s_flag &= ~SSIZEVALID;

        /*
         * Only call the close routine when the last open reference through
         * any [s, v]node goes away.  This can be checked by looking at
         * s_count on the common vnode.
         */
        if ((csp->s_count == 0) && (csp->s_mapcnt == 0)) {
                /* we don't need a close */
                csp->s_flag &= ~(SNEEDCLOSE | SSIZEVALID);

                /*
                 * A cloning driver may open-clone to the same dev_t that we
                 * are closing before spec_inactive destroys the common snode.
                 * If this occurs the s_dip association needs to be reevaluated.
                 * We clear SDIPSET to force reevaluation in this case.  When
                 * reevaluation occurs (by spec_clone after open), if the
                 * devinfo association has changed then the old association
                 * will be released as the new association is established by
                 * spec_assoc_vp_with_devi().
                 */
                if (csp->s_flag & (SCLONE | SSELFCLONE))
                        csp->s_flag &= ~SDIPSET;

                csp->s_flag |= SCLOSING;
                mutex_exit(&csp->s_lock);
                error = device_close(vp, flag, cr);

                /*
                 * Decrement the devops held in clnopen()
                 */
                if (sysclone) {
                        ddi_rele_driver(getmajor(dev));
                }
                mutex_enter(&csp->s_lock);
                csp->s_flag &= ~SCLOSING;
        }

        UNLOCK_CSP_LOCK_HELD(csp);
        mutex_exit(&csp->s_lock);

        return (error);
}

/*ARGSUSED2*/
static int
spec_read(
        struct vnode    *vp,
        struct uio      *uiop,
        int             ioflag,
        struct cred     *cr,
        caller_context_t *ct)
{
        int error;
        struct snode *sp = VTOS(vp);
        dev_t dev = sp->s_dev;
        size_t n;
        ulong_t on;
        uoff_t bdevsize;
        offset_t maxoff;
        offset_t off;
        struct vnode *blkvp;

        ASSERT(vp->v_type == VCHR || vp->v_type == VBLK);

        if (vp->v_stream) {
                ASSERT(vp->v_type == VCHR);
                smark(sp, SACC);
                return (strread(vp, uiop, cr));
        }

        if (uiop->uio_resid == 0)
                return (0);

        /*
         * Plain old character devices that set D_U64BIT can have
         * unrestricted offsets.
         */
        maxoff = spec_maxoffset(vp);
        ASSERT(maxoff != -1 || vp->v_type == VCHR);

        if (maxoff != -1 && (uiop->uio_loffset < 0 ||
            uiop->uio_loffset + uiop->uio_resid > maxoff))
                return (EINVAL);

        if (vp->v_type == VCHR) {
                smark(sp, SACC);
                ASSERT(vp->v_stream == NULL);
                return (cdev_read(dev, uiop, cr));
        }

        /*
         * Block device.
         */
        error = 0;
        blkvp = sp->s_commonvp;
        bdevsize = SPEC_SIZE(VTOS(blkvp));

        do {
                caddr_t base;
                offset_t diff;

                off = uiop->uio_loffset & (offset_t)MAXBMASK;
                on = (size_t)(uiop->uio_loffset & MAXBOFFSET);
                n = (size_t)MIN(MAXBSIZE - on, uiop->uio_resid);
                diff = bdevsize - uiop->uio_loffset;

                if (diff <= 0)
                        break;
                if (diff < n)
                        n = (size_t)diff;

                if (vpm_enable) {
                        error = vpm_data_copy(blkvp, (uoff_t)(off + on),
                            n, uiop, 1, NULL, 0, S_READ);
                } else {
                        base = segmap_getmapflt(segkmap, blkvp,
                            (uoff_t)(off + on), n, 1, S_READ);

                        error = uiomove(base + on, n, UIO_READ, uiop);
                }
                if (!error) {
                        int flags = 0;
                        /*
                         * If we read a whole block, we won't need this
                         * buffer again soon.
                         */
                        if (n + on == MAXBSIZE)
                                flags = SM_DONTNEED | SM_FREE;
                        if (vpm_enable) {
                                error = vpm_sync_pages(blkvp, off, n, flags);
                        } else {
                                error = segmap_release(segkmap, base, flags);
                        }
                } else {
                        if (vpm_enable) {
                                (void) vpm_sync_pages(blkvp, off, n, 0);
                        } else {
                                (void) segmap_release(segkmap, base, 0);
                        }
                        if (bdevsize == UNKNOWN_SIZE) {
                                error = 0;
                                break;
                        }
                }
        } while (error == 0 && uiop->uio_resid > 0 && n != 0);

        return (error);
}

/*ARGSUSED*/
static int
spec_write(
        struct vnode *vp,
        struct uio *uiop,
        int ioflag,
        struct cred *cr,
        caller_context_t *ct)
{
        int error;
        struct snode *sp = VTOS(vp);
        dev_t dev = sp->s_dev;
        size_t n;
        ulong_t on;
        uoff_t bdevsize;
        offset_t maxoff;
        offset_t off;
        struct vnode *blkvp;

        ASSERT(vp->v_type == VCHR || vp->v_type == VBLK);

        if (vp->v_stream) {
                ASSERT(vp->v_type == VCHR);
                smark(sp, SUPD);
                return (strwrite(vp, uiop, cr));
        }

        /*
         * Plain old character devices that set D_U64BIT can have
         * unrestricted offsets.
         */
        maxoff = spec_maxoffset(vp);
        ASSERT(maxoff != -1 || vp->v_type == VCHR);

        if (maxoff != -1 && (uiop->uio_loffset < 0 ||
            uiop->uio_loffset + uiop->uio_resid > maxoff))
                return (EINVAL);

        if (vp->v_type == VCHR) {
                smark(sp, SUPD);
                ASSERT(vp->v_stream == NULL);
                return (cdev_write(dev, uiop, cr));
        }

        if (uiop->uio_resid == 0)
                return (0);

        error = 0;
        blkvp = sp->s_commonvp;
        bdevsize = SPEC_SIZE(VTOS(blkvp));

        do {
                int pagecreate;
                int newpage;
                caddr_t base;
                offset_t diff;

                off = uiop->uio_loffset & (offset_t)MAXBMASK;
                on = (ulong_t)(uiop->uio_loffset & MAXBOFFSET);
                n = (size_t)MIN(MAXBSIZE - on, uiop->uio_resid);
                pagecreate = 0;

                diff = bdevsize - uiop->uio_loffset;
                if (diff <= 0) {
                        error = ENXIO;
                        break;
                }
                if (diff < n)
                        n = (size_t)diff;

                /*
                 * Check to see if we can skip reading in the page
                 * and just allocate the memory.  We can do this
                 * if we are going to rewrite the entire mapping
                 * or if we are going to write to end of the device
                 * from the beginning of the mapping.
                 */
                if (n == MAXBSIZE || (on == 0 && (off + n) == bdevsize))
                        pagecreate = 1;

                newpage = 0;

                /*
                 * Touch the page and fault it in if it is not in core
                 * before segmap_getmapflt or vpm_data_copy can lock it.
                 * This is to avoid the deadlock if the buffer is mapped
                 * to the same file through mmap which we want to write.
                 */
                uio_prefaultpages((long)n, uiop);

                if (vpm_enable) {
                        error = vpm_data_copy(blkvp, (uoff_t)(off + on),
                            n, uiop, !pagecreate, NULL, 0, S_WRITE);
                } else {
                        base = segmap_getmapflt(segkmap, blkvp,
                            (uoff_t)(off + on), n, !pagecreate, S_WRITE);

                        /*
                         * segmap_pagecreate() returns 1 if it calls
                         * page_create_va() to allocate any pages.
                         */

                        if (pagecreate)
                                newpage = segmap_pagecreate(segkmap, base + on,
                                    n, 0);

                        error = uiomove(base + on, n, UIO_WRITE, uiop);
                }

                if (!vpm_enable && pagecreate &&
                    uiop->uio_loffset <
                    P2ROUNDUP_TYPED(off + on + n, PAGESIZE, offset_t)) {
                        /*
                         * We created pages w/o initializing them completely,
                         * thus we need to zero the part that wasn't set up.
                         * This can happen if we write to the end of the device
                         * or if we had some sort of error during the uiomove.
                         */
                        long nzero;
                        offset_t nmoved;

                        nmoved = (uiop->uio_loffset - (off + on));
                        if (nmoved < 0 || nmoved > n) {
                                panic("spec_write: nmoved bogus");
                                /*NOTREACHED*/
                        }
                        nzero = (long)P2ROUNDUP(on + n, PAGESIZE) -
                            (on + nmoved);
                        if (nzero < 0 || (on + nmoved + nzero > MAXBSIZE)) {
                                panic("spec_write: nzero bogus");
                                /*NOTREACHED*/
                        }
                        (void) kzero(base + on + nmoved, (size_t)nzero);
                }

                /*
                 * Unlock the pages which have been allocated by
                 * page_create_va() in segmap_pagecreate().
                 */
                if (!vpm_enable && newpage)
                        segmap_pageunlock(segkmap, base + on,
                            (size_t)n, S_WRITE);

                if (error == 0) {
                        int flags = 0;

                        /*
                         * Force write back for synchronous write cases.
                         */
                        if (ioflag & (FSYNC|FDSYNC))
                                flags = SM_WRITE;
                        else if (n + on == MAXBSIZE || IS_SWAPVP(vp)) {
                                /*
                                 * Have written a whole block.
                                 * Start an asynchronous write and
                                 * mark the buffer to indicate that
                                 * it won't be needed again soon.
                                 * Push swap files here, since it
                                 * won't happen anywhere else.
                                 */
                                flags = SM_WRITE | SM_ASYNC | SM_DONTNEED;
                        }
                        smark(sp, SUPD|SCHG);
                        if (vpm_enable) {
                                error = vpm_sync_pages(blkvp, off, n, flags);
                        } else {
                                error = segmap_release(segkmap, base, flags);
                        }
                } else {
                        if (vpm_enable) {
                                (void) vpm_sync_pages(blkvp, off, n, SM_INVAL);
                        } else {
                                (void) segmap_release(segkmap, base, SM_INVAL);
                        }
                }

        } while (error == 0 && uiop->uio_resid > 0 && n != 0);

        return (error);
}

/*ARGSUSED6*/
static int
spec_ioctl(struct vnode *vp, int cmd, intptr_t arg, int mode, struct cred *cr,
    int *rvalp, caller_context_t *ct)
{
        struct snode *sp;
        dev_t dev;
        int error;

        if (vp->v_type != VCHR)
                return (ENOTTY);

        /*
         * allow ioctls() to go through even for fenced snodes, as they
         * may include unconfiguration operation - for example popping of
         * streams modules.
         */

        sp = VTOS(vp);
        dev = sp->s_dev;
        if (vp->v_stream) {
                error = strioctl(vp, cmd, arg, mode, U_TO_K, cr, rvalp);
        } else {
                error = cdev_ioctl(dev, cmd, arg, mode, cr, rvalp);
        }
        return (error);
}

static int
spec_getattr(
        struct vnode *vp,
        struct vattr *vap,
        int flags,
        struct cred *cr,
        caller_context_t *ct)
{
        int error;
        struct snode *sp;
        struct vnode *realvp;

        /* With ATTR_COMM we will not get attributes from realvp */
        if (flags & ATTR_COMM) {
                sp = VTOS(vp);
                vp = sp->s_commonvp;
        }
        sp = VTOS(vp);

        /* we want stat() to fail with ENXIO if the device is fenced off */
        if (S_ISFENCED(sp))
                return (ENXIO);

        realvp = sp->s_realvp;

        if (realvp == NULL) {
                static int snode_shift  = 0;

                /*
                 * Calculate the amount of bitshift to a snode pointer which
                 * will still keep it unique.  See below.
                 */
                if (snode_shift == 0)
                        snode_shift = highbit(sizeof (struct snode));
                ASSERT(snode_shift > 0);

                /*
                 * No real vnode behind this one.  Fill in the fields
                 * from the snode.
                 *
                 * This code should be refined to return only the
                 * attributes asked for instead of all of them.
                 */
                vap->va_type = vp->v_type;
                vap->va_mode = 0;
                vap->va_uid = vap->va_gid = 0;
                vap->va_fsid = sp->s_fsid;

                /*
                 * If the va_nodeid is > MAX_USHORT, then i386 stats might
                 * fail. So we shift down the snode pointer to try and get
                 * the most uniqueness into 16-bits.
                 */
                vap->va_nodeid = ((ino64_t)(uintptr_t)sp >> snode_shift) &
                    0xFFFF;
                vap->va_nlink = 0;
                vap->va_rdev = sp->s_dev;

                /*
                 * va_nblocks is the number of 512 byte blocks used to store
                 * the mknod for the device, not the number of blocks on the
                 * device itself.  This is typically zero since the mknod is
                 * represented directly in the inode itself.
                 */
                vap->va_nblocks = 0;
        } else {
                error = fop_getattr(realvp, vap, flags, cr, ct);
                if (error != 0)
                        return (error);
        }

        /* set the size from the snode */
        vap->va_size = SPEC_SIZE(VTOS(sp->s_commonvp));
        vap->va_blksize = MAXBSIZE;

        mutex_enter(&sp->s_lock);
        vap->va_atime.tv_sec = sp->s_atime;
        vap->va_mtime.tv_sec = sp->s_mtime;
        vap->va_ctime.tv_sec = sp->s_ctime;
        mutex_exit(&sp->s_lock);

        vap->va_atime.tv_nsec = 0;
        vap->va_mtime.tv_nsec = 0;
        vap->va_ctime.tv_nsec = 0;
        vap->va_seq = 0;

        return (0);
}

static int
spec_setattr(
        struct vnode *vp,
        struct vattr *vap,
        int flags,
        struct cred *cr,
        caller_context_t *ct)
{
        struct snode *sp = VTOS(vp);
        struct vnode *realvp;
        int error;

        /* fail with ENXIO if the device is fenced off */
        if (S_ISFENCED(sp))
                return (ENXIO);

        if (vp->v_type == VCHR && vp->v_stream && (vap->va_mask & AT_SIZE)) {
                /*
                 * 1135080:     O_TRUNC should have no effect on
                 *              named pipes and terminal devices.
                 */
                ASSERT(vap->va_mask == AT_SIZE);
                return (0);
        }

        if ((realvp = sp->s_realvp) == NULL)
                error = 0;      /* no real vnode to update */
        else
                error = fop_setattr(realvp, vap, flags, cr, ct);
        if (error == 0) {
                /*
                 * If times were changed, update snode.
                 */
                mutex_enter(&sp->s_lock);
                if (vap->va_mask & AT_ATIME)
                        sp->s_atime = vap->va_atime.tv_sec;
                if (vap->va_mask & AT_MTIME) {
                        sp->s_mtime = vap->va_mtime.tv_sec;
                        sp->s_ctime = gethrestime_sec();
                }
                mutex_exit(&sp->s_lock);
        }
        return (error);
}

static int
spec_access(
        struct vnode *vp,
        int mode,
        int flags,
        struct cred *cr,
        caller_context_t *ct)
{
        struct vnode *realvp;
        struct snode *sp = VTOS(vp);

        /* fail with ENXIO if the device is fenced off */
        if (S_ISFENCED(sp))
                return (ENXIO);

        if ((realvp = sp->s_realvp) != NULL)
                return (fop_access(realvp, mode, flags, cr, ct));
        else
                return (0);     /* Allow all access. */
}

/*
 * This can be called if creat or an open with O_CREAT is done on the root
 * of a lofs mount where the mounted entity is a special file.
 */
/*ARGSUSED*/
static int
spec_create(
        struct vnode *dvp,
        char *name,
        vattr_t *vap,
        enum vcexcl excl,
        int mode,
        struct vnode **vpp,
        struct cred *cr,
        int flag,
        caller_context_t *ct,
        vsecattr_t *vsecp)
{
        int error;
        struct snode *sp = VTOS(dvp);

        /* fail with ENXIO if the device is fenced off */
        if (S_ISFENCED(sp))
                return (ENXIO);

        ASSERT(dvp && (dvp->v_flag & VROOT) && *name == '\0');
        if (excl == NONEXCL) {
                if (mode && (error = spec_access(dvp, mode, 0, cr, ct)))
                        return (error);
                VN_HOLD(dvp);
                return (0);
        }
        return (EEXIST);
}

/*
 * In order to sync out the snode times without multi-client problems,
 * make sure the times written out are never earlier than the times
 * already set in the vnode.
 */
static int
spec_fsync(
        struct vnode *vp,
        int syncflag,
        struct cred *cr,
        caller_context_t *ct)
{
        struct snode *sp = VTOS(vp);
        struct vnode *realvp;
        struct vnode *cvp;
        struct vattr va, vatmp;

        /* allow syncing even if device is fenced off */

        /* If times didn't change, don't flush anything. */
        mutex_enter(&sp->s_lock);
        if ((sp->s_flag & (SACC|SUPD|SCHG)) == 0 && vp->v_type != VBLK) {
                mutex_exit(&sp->s_lock);
                return (0);
        }
        sp->s_flag &= ~(SACC|SUPD|SCHG);
        mutex_exit(&sp->s_lock);
        cvp = sp->s_commonvp;
        realvp = sp->s_realvp;

        if (vp->v_type == VBLK && cvp != vp && vn_has_cached_data(cvp) &&
            (cvp->v_flag & VISSWAP) == 0)
                (void) fop_putpage(cvp, 0, 0, 0, cr, ct);

        /*
         * For devices that support it, force write cache to stable storage.
         * We don't need the lock to check s_flags since we can treat
         * SNOFLUSH as a hint.
         */
        if ((vp->v_type == VBLK || vp->v_type == VCHR) &&
            !(sp->s_flag & SNOFLUSH)) {
                int rval, rc;
                struct dk_callback spec_callback;

                spec_callback.dkc_flag = FLUSH_VOLATILE;
                spec_callback.dkc_callback = NULL;

                /* synchronous flush on volatile cache */
                rc = cdev_ioctl(vp->v_rdev, DKIOCFLUSHWRITECACHE,
                    (intptr_t)&spec_callback, FNATIVE|FKIOCTL, cr, &rval);

                if (rc == ENOTSUP || rc == ENOTTY) {
                        mutex_enter(&sp->s_lock);
                        sp->s_flag |= SNOFLUSH;
                        mutex_exit(&sp->s_lock);
                }
        }

        /*
         * If no real vnode to update, don't flush anything.
         */
        if (realvp == NULL)
                return (0);

        vatmp.va_mask = AT_ATIME|AT_MTIME;
        if (fop_getattr(realvp, &vatmp, 0, cr, ct) == 0) {

                mutex_enter(&sp->s_lock);
                if (vatmp.va_atime.tv_sec > sp->s_atime)
                        va.va_atime = vatmp.va_atime;
                else {
                        va.va_atime.tv_sec = sp->s_atime;
                        va.va_atime.tv_nsec = 0;
                }
                if (vatmp.va_mtime.tv_sec > sp->s_mtime)
                        va.va_mtime = vatmp.va_mtime;
                else {
                        va.va_mtime.tv_sec = sp->s_mtime;
                        va.va_mtime.tv_nsec = 0;
                }
                mutex_exit(&sp->s_lock);

                va.va_mask = AT_ATIME|AT_MTIME;
                (void) fop_setattr(realvp, &va, 0, cr, ct);
        }
        (void) fop_fsync(realvp, syncflag, cr, ct);
        return (0);
}

/*ARGSUSED*/
static void
spec_inactive(struct vnode *vp, struct cred *cr, caller_context_t *ct)
{
        struct snode *sp = VTOS(vp);
        struct vnode *cvp;
        struct vnode *rvp;

        /*
         * If no one has reclaimed the vnode, remove from the
         * cache now.
         */
        if (vp->v_count < 1) {
                panic("spec_inactive: Bad v_count");
                /*NOTREACHED*/
        }
        mutex_enter(&stable_lock);

        mutex_enter(&vp->v_lock);
        VN_RELE_LOCKED(vp);
        if (vp->v_count != 0) {
                mutex_exit(&vp->v_lock);
                mutex_exit(&stable_lock);
                return;
        }
        mutex_exit(&vp->v_lock);

        sdelete(sp);
        mutex_exit(&stable_lock);

        /* We are the sole owner of sp now */
        cvp = sp->s_commonvp;
        rvp = sp->s_realvp;

        if (rvp) {
                /*
                 * If the snode times changed, then update the times
                 * associated with the "realvp".
                 */
                if ((sp->s_flag & (SACC|SUPD|SCHG)) != 0) {

                        struct vattr va, vatmp;

                        mutex_enter(&sp->s_lock);
                        sp->s_flag &= ~(SACC|SUPD|SCHG);
                        mutex_exit(&sp->s_lock);
                        vatmp.va_mask = AT_ATIME|AT_MTIME;
                        /*
                         * The user may not own the device, but we
                         * want to update the attributes anyway.
                         */
                        if (fop_getattr(rvp, &vatmp, 0, kcred, ct) == 0) {
                                if (vatmp.va_atime.tv_sec > sp->s_atime)
                                        va.va_atime = vatmp.va_atime;
                                else {
                                        va.va_atime.tv_sec = sp->s_atime;
                                        va.va_atime.tv_nsec = 0;
                                }
                                if (vatmp.va_mtime.tv_sec > sp->s_mtime)
                                        va.va_mtime = vatmp.va_mtime;
                                else {
                                        va.va_mtime.tv_sec = sp->s_mtime;
                                        va.va_mtime.tv_nsec = 0;
                                }

                                va.va_mask = AT_ATIME|AT_MTIME;
                                (void) fop_setattr(rvp, &va, 0, kcred, ct);
                        }
                }
        }
        ASSERT(!vn_has_cached_data(vp));
        vn_invalid(vp);

        /* if we are sharing another file systems vfs, release it */
        if (vp->v_vfsp && (vp->v_vfsp != &spec_vfs))
                VFS_RELE(vp->v_vfsp);

        /* if we have a realvp, release the realvp */
        if (rvp)
                VN_RELE(rvp);

        /* if we have a common, release the common */
        if (cvp && (cvp != vp)) {
                VN_RELE(cvp);
#ifdef DEBUG
        } else if (cvp) {
                /*
                 * if this is the last reference to a common vnode, any
                 * associated stream had better have been closed
                 */
                ASSERT(cvp == vp);
                ASSERT(cvp->v_stream == NULL);
#endif /* DEBUG */
        }

        /*
         * if we have a hold on a devinfo node (established by
         * spec_assoc_vp_with_devi), release the hold
         */
        if (sp->s_dip)
                ddi_release_devi(sp->s_dip);

        /*
         * If we have an associated device policy, release it.
         */
        if (sp->s_plcy != NULL)
                dpfree(sp->s_plcy);

        /*
         * If all holds on the devinfo node are through specfs/devfs
         * and we just destroyed the last specfs node associated with the
         * device, then the devinfo node reference count should now be
         * zero.  We can't check this because there may be other holds
         * on the node from non file system sources: ddi_hold_devi_by_instance
         * for example.
         */
        kmem_cache_free(snode_cache, sp);
}

static int
spec_fid(struct vnode *vp, struct fid *fidp, caller_context_t *ct)
{
        struct vnode *realvp;
        struct snode *sp = VTOS(vp);

        if ((realvp = sp->s_realvp) != NULL)
                return (fop_fid(realvp, fidp, ct));
        else
                return (EINVAL);
}

/*ARGSUSED1*/
static int
spec_seek(
        struct vnode *vp,
        offset_t ooff,
        offset_t *noffp,
        caller_context_t *ct)
{
        offset_t maxoff = spec_maxoffset(vp);

        if (maxoff == -1 || *noffp <= maxoff)
                return (0);
        else
                return (EINVAL);
}

static int
spec_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)
{
        struct snode *sp = VTOS(vp);
        struct snode *csp;

        csp = VTOS(sp->s_commonvp);
        /*
         * If file is being mapped, disallow frlock.
         */
        if (csp->s_mapcnt > 0)
                return (EAGAIN);

        return (fs_frlock(vp, cmd, bfp, flag, offset, flk_cbp, cr, ct));
}

static int
spec_realvp(struct vnode *vp, struct vnode **vpp, caller_context_t *ct)
{
        struct vnode *rvp;

        if ((rvp = VTOS(vp)->s_realvp) != NULL) {
                vp = rvp;
                if (fop_realvp(vp, &rvp, ct) == 0)
                        vp = rvp;
        }

        *vpp = vp;
        return (0);
}

/*
 * Return all the pages from [off..off + len] in block
 * or character device.
 */
/*ARGSUSED*/
static int
spec_getpage(
        struct vnode    *vp,
        offset_t        off,
        size_t          len,
        uint_t          *protp,
        page_t          *pl[],
        size_t          plsz,
        struct seg      *seg,
        caddr_t         addr,
        enum seg_rw     rw,
        struct cred     *cr,
        caller_context_t *ct)
{
        struct snode *sp = VTOS(vp);
        int err;

        ASSERT(sp->s_commonvp == vp);

        /*
         * XXX  Given the above assertion, this might not do
         *      what is wanted here.
         */
        if (vp->v_flag & VNOMAP)
                return (ENOSYS);
        TRACE_4(TR_FAC_SPECFS, TR_SPECFS_GETPAGE,
            "specfs getpage:vp %p off %llx len %ld snode %p",
            vp, off, len, sp);

        switch (vp->v_type) {
        case VBLK:
                if (protp != NULL)
                        *protp = PROT_ALL;

                if (((uoff_t)off + len) > (SPEC_SIZE(sp) + PAGEOFFSET))
                        return (EFAULT);        /* beyond EOF */

                err = pvn_getpages(spec_getapage, vp, (uoff_t)off, len,
                    protp, pl, plsz, seg, addr, rw, cr);
                break;

        case VCHR:
                cmn_err(CE_NOTE, "spec_getpage called for character device. "
                    "Check any non-ON consolidation drivers");
                err = 0;
                pl[0] = (page_t *)0;
                break;

        default:
                panic("spec_getpage: bad v_type 0x%x", vp->v_type);
                /*NOTREACHED*/
        }

        return (err);
}

extern int klustsize;   /* set in machdep.c */

int spec_ra = 1;
int spec_lostpage;      /* number of times we lost original page */

/*ARGSUSED2*/
static int
spec_getapage(
        struct vnode *vp,
        uoff_t  off,
        size_t          len,
        uint_t          *protp,
        page_t          *pl[],
        size_t          plsz,
        struct seg      *seg,
        caddr_t         addr,
        enum seg_rw     rw,
        struct cred     *cr)
{
        struct snode *sp;
        struct buf *bp;
        page_t *pp, *pp2;
        uoff_t io_off1, io_off2;
        size_t io_len1;
        size_t io_len2;
        size_t blksz;
        uoff_t blkoff;
        int dora, err;
        page_t *pagefound;
        uint_t xlen;
        size_t adj_klustsize;
        uoff_t size;
        uoff_t tmpoff;

        sp = VTOS(vp);
        TRACE_3(TR_FAC_SPECFS, TR_SPECFS_GETAPAGE,
            "specfs getapage:vp %p off %llx snode %p", vp, off, sp);
reread:

        err = 0;
        bp = NULL;
        pp = NULL;
        pp2 = NULL;

        if (pl != NULL)
                pl[0] = NULL;

        size = SPEC_SIZE(VTOS(sp->s_commonvp));

        if (spec_ra && sp->s_nextr == off)
                dora = 1;
        else
                dora = 0;

        if (size == UNKNOWN_SIZE) {
                dora = 0;
                adj_klustsize = PAGESIZE;
        } else {
                adj_klustsize = dora ? klustsize : PAGESIZE;
        }

again:
        if ((pagefound = page_exists(&vp->v_object, off)) == NULL) {
                if (rw == S_CREATE) {
                        /*
                         * We're allocating a swap slot and it's
                         * associated page was not found, so allocate
                         * and return it.
                         */
                        if ((pp = page_create_va(&vp->v_object, off,
                            PAGESIZE, PG_WAIT, seg, addr)) == NULL) {
                                panic("spec_getapage: page_create");
                                /*NOTREACHED*/
                        }
                        io_len1 = PAGESIZE;
                        sp->s_nextr = off + PAGESIZE;
                } else {
                        /*
                         * Need to really do disk I/O to get the page(s).
                         */
                        blkoff = (off / adj_klustsize) * adj_klustsize;
                        if (size == UNKNOWN_SIZE) {
                                blksz = PAGESIZE;
                        } else {
                                if (blkoff + adj_klustsize <= size)
                                        blksz = adj_klustsize;
                                else
                                        blksz =
                                            MIN(size - blkoff, adj_klustsize);
                        }

                        pp = pvn_read_kluster(vp, off, seg, addr, &tmpoff,
                            &io_len1, blkoff, blksz, 0);
                        io_off1 = tmpoff;
                        /*
                         * Make sure the page didn't sneek into the
                         * cache while we blocked in pvn_read_kluster.
                         */
                        if (pp == NULL)
                                goto again;

                        /*
                         * Zero part of page which we are not
                         * going to be reading from disk now.
                         */
                        xlen = (uint_t)(io_len1 & PAGEOFFSET);
                        if (xlen != 0)
                                pagezero(pp->p_prev, xlen, PAGESIZE - xlen);

                        bp = spec_startio(vp, pp, io_off1, io_len1,
                            pl == NULL ? (B_ASYNC | B_READ) : B_READ);
                        sp->s_nextr = io_off1 + io_len1;
                }
        }

        if (dora && rw != S_CREATE) {
                uoff_t off2;
                caddr_t addr2;

                off2 = ((off / adj_klustsize) + 1) * adj_klustsize;
                addr2 = addr + (off2 - off);

                pp2 = NULL;
                /*
                 * If we are past EOF then don't bother trying
                 * with read-ahead.
                 */
                if (off2 >= size)
                        pp2 = NULL;
                else {
                        if (off2 + adj_klustsize <= size)
                                blksz = adj_klustsize;
                        else
                                blksz = MIN(size - off2, adj_klustsize);

                        pp2 = pvn_read_kluster(vp, off2, seg, addr2, &tmpoff,
                            &io_len2, off2, blksz, 1);
                        io_off2 = tmpoff;
                }

                if (pp2 != NULL) {
                        /*
                         * Zero part of page which we are not
                         * going to be reading from disk now.
                         */
                        xlen = (uint_t)(io_len2 & PAGEOFFSET);
                        if (xlen != 0)
                                pagezero(pp2->p_prev, xlen, PAGESIZE - xlen);

                        (void) spec_startio(vp, pp2, io_off2, io_len2,
                            B_READ | B_ASYNC);
                }
        }

        if (pl == NULL)
                return (err);

        if (bp != NULL) {
                err = biowait(bp);
                pageio_done(bp);

                if (err) {
                        if (pp != NULL)
                                pvn_read_done(pp, B_ERROR);
                        return (err);
                }
        }

        if (pagefound) {
                se_t se = (rw == S_CREATE ? SE_EXCL : SE_SHARED);
                /*
                 * Page exists in the cache, acquire the appropriate
                 * lock.  If this fails, start all over again.
                 */

                if ((pp = page_lookup(&vp->v_object, off, se)) == NULL) {
                        spec_lostpage++;
                        goto reread;
                }
                pl[0] = pp;
                pl[1] = NULL;

                sp->s_nextr = off + PAGESIZE;
                return (0);
        }

        if (pp != NULL)
                pvn_plist_init(pp, pl, plsz, off, io_len1, rw);
        return (0);
}

/*
 * Flags are composed of {B_INVAL, B_DIRTY B_FREE, B_DONTNEED, B_FORCE}.
 * If len == 0, do from off to EOF.
 *
 * The normal cases should be len == 0 & off == 0 (entire vp list),
 * len == MAXBSIZE (from segmap_release actions), and len == PAGESIZE
 * (from pageout).
 */
/*ARGSUSED5*/
int
spec_putpage(
        struct vnode *vp,
        offset_t        off,
        size_t          len,
        int             flags,
        struct cred     *cr,
        caller_context_t *ct)
{
        struct snode *sp = VTOS(vp);
        struct vnode *cvp;
        page_t *pp;
        uoff_t io_off;
        size_t io_len = 0;      /* for lint */
        int err = 0;
        uoff_t size;
        uoff_t tmpoff;

        ASSERT(vp->v_count != 0);

        if (vp->v_flag & VNOMAP)
                return (ENOSYS);

        cvp = sp->s_commonvp;
        size = SPEC_SIZE(VTOS(cvp));

        if (!vn_has_cached_data(vp) || off >= size)
                return (0);

        ASSERT(vp->v_type == VBLK && cvp == vp);
        TRACE_4(TR_FAC_SPECFS, TR_SPECFS_PUTPAGE,
            "specfs putpage:vp %p off %llx len %ld snode %p",
            vp, off, len, sp);

        if (len == 0) {
                /*
                 * Search the entire vp list for pages >= off.
                 */
                err = pvn_vplist_dirty(vp, off, spec_putapage,
                    flags, cr);
        } else {
                uoff_t eoff;

                /*
                 * Loop over all offsets in the range [off...off + len]
                 * looking for pages to deal with.  We set limits so
                 * that we kluster to klustsize boundaries.
                 */
                eoff = off + len;
                for (io_off = off; io_off < eoff && io_off < size;
                    io_off += io_len) {
                        /*
                         * If we are not invalidating, synchronously
                         * freeing or writing pages use the routine
                         * page_lookup_nowait() to prevent reclaiming
                         * them from the free list.
                         */
                        if ((flags & B_INVAL) || ((flags & B_ASYNC) == 0)) {
                                pp = page_lookup(&vp->v_object, io_off,
                                                 (flags & (B_INVAL | B_FREE)) ? SE_EXCL : SE_SHARED);
                        } else {
                                pp = page_lookup_nowait(&vp->v_object,
                                                        io_off,
                                                        (flags & B_FREE) ? SE_EXCL : SE_SHARED);
                        }

                        if (pp == NULL || pvn_getdirty(pp, flags) == 0)
                                io_len = PAGESIZE;
                        else {
                                err = spec_putapage(vp, pp, &tmpoff, &io_len,
                                    flags, cr);
                                io_off = tmpoff;
                                if (err != 0)
                                        break;
                                /*
                                 * "io_off" and "io_len" are returned as
                                 * the range of pages we actually wrote.
                                 * This allows us to skip ahead more quickly
                                 * since several pages may've been dealt
                                 * with by this iteration of the loop.
                                 */
                        }
                }
        }
        return (err);
}


/*
 * Write out a single page, possibly klustering adjacent
 * dirty pages.
 */
/*ARGSUSED5*/
static int
spec_putapage(
        struct vnode    *vp,
        page_t          *pp,
        uoff_t  *offp,          /* return value */
        size_t          *lenp,          /* return value */
        int             flags,
        struct cred     *cr)
{
        struct snode *sp = VTOS(vp);
        uoff_t io_off;
        size_t io_len;
        size_t blksz;
        uoff_t blkoff;
        int err = 0;
        struct buf *bp;
        uoff_t size;
        size_t adj_klustsize;
        uoff_t tmpoff;

        /*
         * Destroy read ahead value since we are really going to write.
         */
        sp->s_nextr = 0;
        size = SPEC_SIZE(VTOS(sp->s_commonvp));

        adj_klustsize = klustsize;

        blkoff = (pp->p_offset / adj_klustsize) * adj_klustsize;

        if (blkoff + adj_klustsize <= size)
                blksz = adj_klustsize;
        else
                blksz = size - blkoff;

        /*
         * Find a kluster that fits in one contiguous chunk.
         */
        pp = pvn_write_kluster(vp, pp, &tmpoff, &io_len, blkoff,
            blksz, flags);
        io_off = tmpoff;

        /*
         * Check for page length rounding problems
         * XXX - Is this necessary?
         */
        if (io_off + io_len > size) {
                ASSERT((io_off + io_len) - size < PAGESIZE);
                io_len = size - io_off;
        }

        bp = spec_startio(vp, pp, io_off, io_len, B_WRITE | flags);

        /*
         * Wait for i/o to complete if the request is not B_ASYNC.
         */
        if ((flags & B_ASYNC) == 0) {
                err = biowait(bp);
                pageio_done(bp);
                pvn_write_done(pp, ((err) ? B_ERROR : 0) | B_WRITE | flags);
        }

        if (offp)
                *offp = io_off;
        if (lenp)
                *lenp = io_len;
        TRACE_4(TR_FAC_SPECFS, TR_SPECFS_PUTAPAGE,
            "specfs putapage:vp %p offp %p snode %p err %d",
            vp, offp, sp, err);
        return (err);
}

/*
 * Flags are composed of {B_ASYNC, B_INVAL, B_FREE, B_DONTNEED}
 */
static struct buf *
spec_startio(
        struct vnode *vp,
        page_t          *pp,
        uoff_t  io_off,
        size_t          io_len,
        int             flags)
{
        struct buf *bp;

        bp = pageio_setup(pp, io_len, vp, flags);

        bp->b_edev = vp->v_rdev;
        bp->b_dev = cmpdev(vp->v_rdev);
        bp->b_blkno = btodt(io_off);
        bp->b_un.b_addr = (caddr_t)0;

        (void) bdev_strategy(bp);

        if (flags & B_READ)
                lwp_stat_update(LWP_STAT_INBLK, 1);
        else
                lwp_stat_update(LWP_STAT_OUBLK, 1);

        return (bp);
}

static int
spec_poll(
        struct vnode    *vp,
        short           events,
        int             anyyet,
        short           *reventsp,
        struct pollhead **phpp,
        caller_context_t *ct)
{
        dev_t dev;
        int error;

        if (vp->v_type == VBLK)
                error = fs_poll(vp, events, anyyet, reventsp, phpp, ct);
        else {
                ASSERT(vp->v_type == VCHR);
                dev = vp->v_rdev;
                if (vp->v_stream) {
                        ASSERT(vp->v_stream != NULL);
                        error = strpoll(vp->v_stream, events, anyyet,
                            reventsp, phpp);
                } else if (devopsp[getmajor(dev)]->devo_cb_ops->cb_chpoll) {
                        error = cdev_poll(dev, events, anyyet, reventsp, phpp);
                } else {
                        error = fs_poll(vp, events, anyyet, reventsp, phpp, ct);
                }
        }
        return (error);
}

/*
 * This routine is called through the cdevsw[] table to handle
 * traditional mmap'able devices that support a d_mmap function.
 */
/*ARGSUSED8*/
int
spec_segmap(
        dev_t dev,
        off_t off,
        struct as *as,
        caddr_t *addrp,
        off_t len,
        uint_t prot,
        uint_t maxprot,
        uint_t flags,
        struct cred *cred)
{
        struct segdev_crargs dev_a;
        int (*mapfunc)(dev_t dev, off_t off, int prot);
        size_t i;
        int     error;

        if ((mapfunc = devopsp[getmajor(dev)]->devo_cb_ops->cb_mmap) == nodev)
                return (ENODEV);
        TRACE_4(TR_FAC_SPECFS, TR_SPECFS_SEGMAP,
            "specfs segmap:dev %x as %p len %lx prot %x",
            dev, as, len, prot);

        /*
         * Character devices that support the d_mmap
         * interface can only be mmap'ed shared.
         */
        if ((flags & MAP_TYPE) != MAP_SHARED)
                return (EINVAL);

        /*
         * Check to ensure that the entire range is
         * legal and we are not trying to map in
         * more than the device will let us.
         */
        for (i = 0; i < len; i += PAGESIZE) {
                if (cdev_mmap(mapfunc, dev, off + i, maxprot) == -1)
                        return (ENXIO);
        }

        as_rangelock(as);
        /* Pick an address w/o worrying about any vac alignment constraints. */
        error = choose_addr(as, addrp, len, off, ADDR_NOVACALIGN, flags);
        if (error != 0) {
                as_rangeunlock(as);
                return (error);
        }

        dev_a.mapfunc = mapfunc;
        dev_a.dev = dev;
        dev_a.offset = off;
        dev_a.prot = (uchar_t)prot;
        dev_a.maxprot = (uchar_t)maxprot;
        dev_a.hat_flags = 0;
        dev_a.hat_attr = 0;
        dev_a.devmap_data = NULL;

        error = as_map(as, *addrp, len, segdev_create, &dev_a);
        as_rangeunlock(as);
        return (error);
}

int
spec_char_map(
        dev_t dev,
        offset_t off,
        struct as *as,
        caddr_t *addrp,
        size_t len,
        uchar_t prot,
        uchar_t maxprot,
        uint_t flags,
        struct cred *cred)
{
        int error = 0;
        major_t maj = getmajor(dev);
        int map_flag;
        int (*segmap)(dev_t, off_t, struct as *,
            caddr_t *, off_t, uint_t, uint_t, uint_t, cred_t *);
        int (*devmap)(dev_t, devmap_cookie_t, offset_t,
            size_t, size_t *, uint_t);
        int (*mmap)(dev_t dev, off_t off, int prot);

        /*
         * Character device: let the device driver
         * pick the appropriate segment driver.
         *
         * 4.x compat.: allow 'NULL' cb_segmap => spec_segmap
         * Kindness: allow 'nulldev' cb_segmap => spec_segmap
         */
        segmap = devopsp[maj]->devo_cb_ops->cb_segmap;
        if (segmap == NULL || segmap == nulldev || segmap == nodev) {
                mmap = devopsp[maj]->devo_cb_ops->cb_mmap;
                map_flag = devopsp[maj]->devo_cb_ops->cb_flag;

                /*
                 * Use old mmap framework if the driver has both mmap
                 * and devmap entry points.  This is to prevent the
                 * system from calling invalid devmap entry point
                 * for some drivers that might have put garbage in the
                 * devmap entry point.
                 */
                if ((map_flag & D_DEVMAP) || mmap == NULL ||
                    mmap == nulldev || mmap == nodev) {
                        devmap = devopsp[maj]->devo_cb_ops->cb_devmap;

                        /*
                         * If driver provides devmap entry point in
                         * cb_ops but not xx_segmap(9E), call
                         * devmap_setup with default settings
                         * (NULL) for callback_ops and driver
                         * callback private data
                         */
                        if (devmap == nodev || devmap == NULL ||
                            devmap == nulldev)
                                return (ENODEV);

                        error = devmap_setup(dev, off, as, addrp,
                            len, prot, maxprot, flags, cred);

                        return (error);
                } else
                        segmap = spec_segmap;
        } else
                segmap = cdev_segmap;

        return ((*segmap)(dev, (off_t)off, as, addrp, len, prot,
            maxprot, flags, cred));
}

/*ARGSUSED9*/
static int
spec_map(
        struct vnode *vp,
        offset_t off,
        struct as *as,
        caddr_t *addrp,
        size_t len,
        uchar_t prot,
        uchar_t maxprot,
        uint_t flags,
        struct cred *cred,
        caller_context_t *ct)
{
        int error = 0;
        struct snode *sp = VTOS(vp);

        if (vp->v_flag & VNOMAP)
                return (ENOSYS);

        /* fail map with ENXIO if the device is fenced off */
        if (S_ISFENCED(sp))
                return (ENXIO);

        /*
         * If file is locked, fail mapping attempt.
         */
        if (vn_has_flocks(vp))
                return (EAGAIN);

        if (vp->v_type == VCHR) {
                return (spec_char_map(vp->v_rdev, off, as, addrp, len, prot,
                    maxprot, flags, cred));
        } else if (vp->v_type == VBLK) {
                struct segvn_crargs vn_a;
                struct vnode *cvp;
                struct snode *sp;

                /*
                 * Block device, use segvn mapping to the underlying commonvp
                 * for pages.
                 */
                if (off > spec_maxoffset(vp))
                        return (ENXIO);

                sp = VTOS(vp);
                cvp = sp->s_commonvp;
                ASSERT(cvp != NULL);

                if (off < 0 || ((offset_t)(off + len) < 0))
                        return (ENXIO);

                as_rangelock(as);
                error = choose_addr(as, addrp, len, off, ADDR_VACALIGN, flags);
                if (error != 0) {
                        as_rangeunlock(as);
                        return (error);
                }

                vn_a.vp = cvp;
                vn_a.offset = off;
                vn_a.type = flags & MAP_TYPE;
                vn_a.prot = (uchar_t)prot;
                vn_a.maxprot = (uchar_t)maxprot;
                vn_a.flags = flags & ~MAP_TYPE;
                vn_a.cred = cred;
                vn_a.amp = NULL;
                vn_a.szc = 0;
                vn_a.lgrp_mem_policy_flags = 0;

                error = as_map(as, *addrp, len, segvn_create, &vn_a);
                as_rangeunlock(as);
        } else
                return (ENODEV);

        return (error);
}

/*ARGSUSED1*/
static int
spec_addmap(
        struct vnode *vp,       /* the common vnode */
        offset_t off,
        struct as *as,
        caddr_t addr,
        size_t len,             /* how many bytes to add */
        uchar_t prot,
        uchar_t maxprot,
        uint_t flags,
        struct cred *cred,
        caller_context_t *ct)
{
        int error = 0;
        struct snode *csp = VTOS(vp);
        ulong_t npages;

        ASSERT(vp != NULL && VTOS(vp)->s_commonvp == vp);

        /*
         * XXX  Given the above assertion, this might not
         *      be a particularly sensible thing to test.
         */
        if (vp->v_flag & VNOMAP)
                return (ENOSYS);

        /* fail with EIO if the device is fenced off */
        if (S_ISFENCED(csp))
                return (EIO);

        npages = btopr(len);
        LOCK_CSP(csp);
        csp->s_mapcnt += npages;

        UNLOCK_CSP(csp);
        return (error);
}

/*ARGSUSED1*/
static int
spec_delmap(
        struct vnode *vp,       /* the common vnode */
        offset_t off,
        struct as *as,
        caddr_t addr,
        size_t len,             /* how many bytes to take away */
        uint_t prot,
        uint_t maxprot,
        uint_t flags,
        struct cred *cred,
        caller_context_t *ct)
{
        struct snode *csp = VTOS(vp);
        ulong_t npages;
        long mcnt;

        /* segdev passes us the common vp */

        ASSERT(vp != NULL && VTOS(vp)->s_commonvp == vp);

        /* allow delmap to succeed even if device fenced off */

        /*
         * XXX  Given the above assertion, this might not
         *      be a particularly sensible thing to test..
         */
        if (vp->v_flag & VNOMAP)
                return (ENOSYS);

        npages = btopr(len);

        LOCK_CSP(csp);
        mutex_enter(&csp->s_lock);
        mcnt = (csp->s_mapcnt -= npages);

        if (mcnt == 0) {
                /*
                 * Call the close routine when the last reference of any
                 * kind through any [s, v]node goes away.  The s_dip hold
                 * on the devinfo node is released when the vnode is
                 * destroyed.
                 */
                if (csp->s_count == 0) {
                        csp->s_flag &= ~(SNEEDCLOSE | SSIZEVALID);

                        /* See comment in spec_close() */
                        if (csp->s_flag & (SCLONE | SSELFCLONE))
                                csp->s_flag &= ~SDIPSET;

                        mutex_exit(&csp->s_lock);

                        (void) device_close(vp, 0, cred);
                } else
                        mutex_exit(&csp->s_lock);

                mutex_enter(&csp->s_lock);
        }
        ASSERT(mcnt >= 0);

        UNLOCK_CSP_LOCK_HELD(csp);
        mutex_exit(&csp->s_lock);

        return (0);
}

/*ARGSUSED4*/
static int
spec_dump(
        struct vnode *vp,
        caddr_t addr,
        offset_t bn,
        offset_t count,
        caller_context_t *ct)
{
        /* allow dump to succeed even if device fenced off */

        ASSERT(vp->v_type == VBLK);
        return (bdev_dump(vp->v_rdev, addr, (daddr_t)bn, (int)count));
}


/*
 * Do i/o on the given page list from/to vp, io_off for io_len.
 * Flags are composed of:
 *      {B_ASYNC, B_INVAL, B_FREE, B_DONTNEED, B_READ, B_WRITE}
 * If B_ASYNC is not set i/o is waited for.
 */
/*ARGSUSED5*/
static int
spec_pageio(
        struct vnode *vp,
        page_t  *pp,
        uoff_t io_off,
        size_t  io_len,
        int     flags,
        cred_t  *cr,
        caller_context_t *ct)
{
        struct buf *bp = NULL;
        int err = 0;

        if (pp == NULL)
                return (EINVAL);

        bp = spec_startio(vp, pp, io_off, io_len, flags);

        /*
         * Wait for i/o to complete if the request is not B_ASYNC.
         */
        if ((flags & B_ASYNC) == 0) {
                err = biowait(bp);
                pageio_done(bp);
        }
        return (err);
}

/*
 * Set ACL on underlying vnode if one exists, or return ENOSYS otherwise.
 */
int
spec_setsecattr(
        struct vnode *vp,
        vsecattr_t *vsap,
        int flag,
        struct cred *cr,
        caller_context_t *ct)
{
        struct vnode *realvp;
        struct snode *sp = VTOS(vp);
        int error;

        /* fail with ENXIO if the device is fenced off */
        if (S_ISFENCED(sp))
                return (ENXIO);

        /*
         * The acl(2) system calls fop_rwlock on the file before setting an
         * ACL, but since specfs does not serialize reads and writes, this
         * VOP does not do anything.  However, some backing file systems may
         * expect the lock to be held before setting an ACL, so it is taken
         * here privately to avoid serializing specfs reads and writes.
         */
        if ((realvp = sp->s_realvp) != NULL) {
                (void) fop_rwlock(realvp, V_WRITELOCK_TRUE, ct);
                error = fop_setsecattr(realvp, vsap, flag, cr, ct);
                (void) fop_rwunlock(realvp, V_WRITELOCK_TRUE, ct);
                return (error);
        } else
                return (fs_nosys());
}

/*
 * Get ACL from underlying vnode if one exists, or fabricate it from
 * the permissions returned by spec_getattr() otherwise.
 */
int
spec_getsecattr(
        struct vnode *vp,
        vsecattr_t *vsap,
        int flag,
        struct cred *cr,
        caller_context_t *ct)
{
        struct vnode *realvp;
        struct snode *sp = VTOS(vp);

        /* fail with ENXIO if the device is fenced off */
        if (S_ISFENCED(sp))
                return (ENXIO);

        if ((realvp = sp->s_realvp) != NULL)
                return (fop_getsecattr(realvp, vsap, flag, cr, ct));
        else
                return (fs_fab_acl(vp, vsap, flag, cr, ct));
}

int
spec_pathconf(
        vnode_t *vp,
        int cmd,
        ulong_t *valp,
        cred_t *cr,
        caller_context_t *ct)
{
        vnode_t *realvp;
        struct snode *sp = VTOS(vp);

        /* fail with ENXIO if the device is fenced off */
        if (S_ISFENCED(sp))
                return (ENXIO);

        if ((realvp = sp->s_realvp) != NULL)
                return (fop_pathconf(realvp, cmd, valp, cr, ct));
        else
                return (fs_pathconf(vp, cmd, valp, cr, ct));
}