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[netbsd-mini2440.git] / sys / dev / dkwedge / dk.c

/*      $NetBSD: dk.c,v 1.51 2009/09/08 21:14:33 pooka Exp $    */

/*-
 * Copyright (c) 2004, 2005, 2006, 2007 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: dk.c,v 1.51 2009/09/08 21:14:33 pooka Exp $");

#ifdef _KERNEL_OPT
#include "opt_dkwedge.h"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/errno.h>
#include <sys/pool.h>
#include <sys/ioctl.h>
#include <sys/disklabel.h>
#include <sys/disk.h>
#include <sys/fcntl.h>
#include <sys/buf.h>
#include <sys/bufq.h>
#include <sys/vnode.h>
#include <sys/stat.h>
#include <sys/conf.h>
#include <sys/callout.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/device.h>
#include <sys/kauth.h>

#include <miscfs/specfs/specdev.h>

MALLOC_DEFINE(M_DKWEDGE, "dkwedge", "Disk wedge structures");

typedef enum {
        DKW_STATE_LARVAL        = 0,
        DKW_STATE_RUNNING       = 1,
        DKW_STATE_DYING         = 2,
        DKW_STATE_DEAD          = 666
} dkwedge_state_t;

struct dkwedge_softc {
        struct device   *sc_dev;        /* pointer to our pseudo-device */
        struct cfdata   sc_cfdata;      /* our cfdata structure */
        uint8_t         sc_wname[128];  /* wedge name (Unicode, UTF-8) */

        dkwedge_state_t sc_state;       /* state this wedge is in */

        struct disk     *sc_parent;     /* parent disk */
        daddr_t         sc_offset;      /* LBA offset of wedge in parent */
        uint64_t        sc_size;        /* size of wedge in blocks */
        char            sc_ptype[32];   /* partition type */
        dev_t           sc_pdev;        /* cached parent's dev_t */
                                        /* link on parent's wedge list */
        LIST_ENTRY(dkwedge_softc) sc_plink;

        struct disk     sc_dk;          /* our own disk structure */
        struct bufq_state *sc_bufq;     /* buffer queue */
        struct callout  sc_restart_ch;  /* callout to restart I/O */

        u_int           sc_iopend;      /* I/Os pending */
        int             sc_flags;       /* flags (splbio) */
};

#define DK_F_WAIT_DRAIN         0x0001  /* waiting for I/O to drain */

static void     dkstart(struct dkwedge_softc *);
static void     dkiodone(struct buf *);
static void     dkrestart(void *);
static void     dkminphys(struct buf *);

static int      dklastclose(struct dkwedge_softc *);
static int      dkwedge_detach(device_t, int);

static dev_type_open(dkopen);
static dev_type_close(dkclose);
static dev_type_read(dkread);
static dev_type_write(dkwrite);
static dev_type_ioctl(dkioctl);
static dev_type_strategy(dkstrategy);
static dev_type_dump(dkdump);
static dev_type_size(dksize);

const struct bdevsw dk_bdevsw = {
        dkopen, dkclose, dkstrategy, dkioctl, dkdump, dksize, D_DISK
};

const struct cdevsw dk_cdevsw = {
        dkopen, dkclose, dkread, dkwrite, dkioctl,
            nostop, notty, nopoll, nommap, nokqfilter, D_DISK
};

static struct dkwedge_softc **dkwedges;
static u_int ndkwedges;
static krwlock_t dkwedges_lock;

static LIST_HEAD(, dkwedge_discovery_method) dkwedge_discovery_methods;
static krwlock_t dkwedge_discovery_methods_lock;

/*
 * dkwedge_match:
 *
 *      Autoconfiguration match function for pseudo-device glue.
 */
static int
dkwedge_match(device_t parent, cfdata_t match,
    void *aux)
{

        /* Pseudo-device; always present. */
        return (1);
}

/*
 * dkwedge_attach:
 *
 *      Autoconfiguration attach function for pseudo-device glue.
 */
static void
dkwedge_attach(device_t parent, device_t self,
    void *aux)
{

        if (!pmf_device_register(self, NULL, NULL))
                aprint_error_dev(self, "couldn't establish power handler\n");
}

CFDRIVER_DECL(dk, DV_DISK, NULL);
CFATTACH_DECL3_NEW(dk, 0,
    dkwedge_match, dkwedge_attach, dkwedge_detach, NULL, NULL, NULL,
    DVF_DETACH_SHUTDOWN);

/*
 * dkwedge_wait_drain:
 *
 *      Wait for I/O on the wedge to drain.
 *      NOTE: Must be called at splbio()!
 */
static void
dkwedge_wait_drain(struct dkwedge_softc *sc)
{

        while (sc->sc_iopend != 0) {
                sc->sc_flags |= DK_F_WAIT_DRAIN;
                (void) tsleep(&sc->sc_iopend, PRIBIO, "dkdrn", 0);
        }
}

/*
 * dkwedge_compute_pdev:
 *
 *      Compute the parent disk's dev_t.
 */
static int
dkwedge_compute_pdev(const char *pname, dev_t *pdevp)
{
        const char *name, *cp;
        int punit, pmaj;
        char devname[16];

        name = pname;
        if ((pmaj = devsw_name2blk(name, devname, sizeof(devname))) == -1)
                return (ENODEV);

        name += strlen(devname);
        for (cp = name, punit = 0; *cp >= '0' && *cp <= '9'; cp++)
                punit = (punit * 10) + (*cp - '0');
        if (cp == name) {
                /* Invalid parent disk name. */
                return (ENODEV);
        }

        *pdevp = MAKEDISKDEV(pmaj, punit, RAW_PART);

        return (0);
}

/*
 * dkwedge_array_expand:
 *
 *      Expand the dkwedges array.
 */
static void
dkwedge_array_expand(void)
{
        int newcnt = ndkwedges + 16;
        struct dkwedge_softc **newarray, **oldarray;

        newarray = malloc(newcnt * sizeof(*newarray), M_DKWEDGE,
            M_WAITOK|M_ZERO);
        if ((oldarray = dkwedges) != NULL)
                memcpy(newarray, dkwedges, ndkwedges * sizeof(*newarray));
        dkwedges = newarray;
        ndkwedges = newcnt;
        if (oldarray != NULL)
                free(oldarray, M_DKWEDGE);
}

static void
dkgetproperties(struct disk *disk, struct dkwedge_info *dkw)
{
        prop_dictionary_t disk_info, odisk_info, geom;

        disk_info = prop_dictionary_create();

        prop_dictionary_set_cstring_nocopy(disk_info, "type", "ESDI");

        geom = prop_dictionary_create();

        prop_dictionary_set_uint64(geom, "sectors-per-unit", dkw->dkw_size);

        prop_dictionary_set_uint32(geom, "sector-size",
            DEV_BSIZE /* XXX 512? */);

        prop_dictionary_set_uint32(geom, "sectors-per-track", 32);

        prop_dictionary_set_uint32(geom, "tracks-per-cylinder", 64);

        prop_dictionary_set_uint32(geom, "cylinders-per-unit", dkw->dkw_size / 2048);

        prop_dictionary_set(disk_info, "geometry", geom);
        prop_object_release(geom);

        odisk_info = disk->dk_info;

        disk->dk_info = disk_info;

        if (odisk_info != NULL)
                prop_object_release(odisk_info);
}

/*
 * dkwedge_add:         [exported function]
 *
 *      Add a disk wedge based on the provided information.
 *
 *      The incoming dkw_devname[] is ignored, instead being
 *      filled in and returned to the caller.
 */
int
dkwedge_add(struct dkwedge_info *dkw)
{
        struct dkwedge_softc *sc, *lsc;
        struct disk *pdk;
        u_int unit;
        int error;
        dev_t pdev;

        dkw->dkw_parent[sizeof(dkw->dkw_parent) - 1] = '\0';
        pdk = disk_find(dkw->dkw_parent);
        if (pdk == NULL)
                return (ENODEV);

        error = dkwedge_compute_pdev(pdk->dk_name, &pdev);
        if (error)
                return (error);

        if (dkw->dkw_offset < 0)
                return (EINVAL);

        sc = malloc(sizeof(*sc), M_DKWEDGE, M_WAITOK|M_ZERO);
        sc->sc_state = DKW_STATE_LARVAL;
        sc->sc_parent = pdk;
        sc->sc_pdev = pdev;
        sc->sc_offset = dkw->dkw_offset;
        sc->sc_size = dkw->dkw_size;

        memcpy(sc->sc_wname, dkw->dkw_wname, sizeof(sc->sc_wname));
        sc->sc_wname[sizeof(sc->sc_wname) - 1] = '\0';

        memcpy(sc->sc_ptype, dkw->dkw_ptype, sizeof(sc->sc_ptype));
        sc->sc_ptype[sizeof(sc->sc_ptype) - 1] = '\0';

        bufq_alloc(&sc->sc_bufq, "fcfs", 0);

        callout_init(&sc->sc_restart_ch, 0);
        callout_setfunc(&sc->sc_restart_ch, dkrestart, sc);

        /*
         * Wedge will be added; increment the wedge count for the parent.
         * Only allow this to happend if RAW_PART is the only thing open.
         */
        mutex_enter(&pdk->dk_openlock);
        if (pdk->dk_openmask & ~(1 << RAW_PART))
                error = EBUSY;
        else {
                /* Check for wedge overlap. */
                LIST_FOREACH(lsc, &pdk->dk_wedges, sc_plink) {
                        daddr_t lastblk = sc->sc_offset + sc->sc_size - 1;
                        daddr_t llastblk = lsc->sc_offset + lsc->sc_size - 1;

                        if (sc->sc_offset >= lsc->sc_offset &&
                            sc->sc_offset <= llastblk) {
                                /* Overlaps the tail of the exsiting wedge. */
                                break;
                        }
                        if (lastblk >= lsc->sc_offset &&
                            lastblk <= llastblk) {
                                /* Overlaps the head of the existing wedge. */
                                break;
                        }
                }
                if (lsc != NULL)
                        error = EINVAL;
                else {
                        pdk->dk_nwedges++;
                        LIST_INSERT_HEAD(&pdk->dk_wedges, sc, sc_plink);
                }
        }
        mutex_exit(&pdk->dk_openlock);
        if (error) {
                bufq_free(sc->sc_bufq);
                free(sc, M_DKWEDGE);
                return (error);
        }

        /* Fill in our cfdata for the pseudo-device glue. */
        sc->sc_cfdata.cf_name = dk_cd.cd_name;
        sc->sc_cfdata.cf_atname = dk_ca.ca_name;
        /* sc->sc_cfdata.cf_unit set below */
        sc->sc_cfdata.cf_fstate = FSTATE_STAR;

        /* Insert the larval wedge into the array. */
        rw_enter(&dkwedges_lock, RW_WRITER);
        for (error = 0;;) {
                struct dkwedge_softc **scpp;

                /*
                 * Check for a duplicate wname while searching for
                 * a slot.
                 */
                for (scpp = NULL, unit = 0; unit < ndkwedges; unit++) {
                        if (dkwedges[unit] == NULL) {
                                if (scpp == NULL) {
                                        scpp = &dkwedges[unit];
                                        sc->sc_cfdata.cf_unit = unit;
                                }
                        } else {
                                /* XXX Unicode. */
                                if (strcmp(dkwedges[unit]->sc_wname,
                                           sc->sc_wname) == 0) {
                                        error = EEXIST;
                                        break;
                                }
                        }
                }
                if (error)
                        break;
                KASSERT(unit == ndkwedges);
                if (scpp == NULL)
                        dkwedge_array_expand();
                else {
                        KASSERT(scpp == &dkwedges[sc->sc_cfdata.cf_unit]);
                        *scpp = sc;
                        break;
                }
        }
        rw_exit(&dkwedges_lock);
        if (error) {
                mutex_enter(&pdk->dk_openlock);
                pdk->dk_nwedges--;
                LIST_REMOVE(sc, sc_plink);
                mutex_exit(&pdk->dk_openlock);

                bufq_free(sc->sc_bufq);
                free(sc, M_DKWEDGE);
                return (error);
        }

        /*
         * Now that we know the unit #, attach a pseudo-device for
         * this wedge instance.  This will provide us with the
         * "struct device" necessary for glue to other parts of the
         * system.
         *
         * This should never fail, unless we're almost totally out of
         * memory.
         */
        if ((sc->sc_dev = config_attach_pseudo(&sc->sc_cfdata)) == NULL) {
                aprint_error("%s%u: unable to attach pseudo-device\n",
                    sc->sc_cfdata.cf_name, sc->sc_cfdata.cf_unit);

                rw_enter(&dkwedges_lock, RW_WRITER);
                dkwedges[sc->sc_cfdata.cf_unit] = NULL;
                rw_exit(&dkwedges_lock);

                mutex_enter(&pdk->dk_openlock);
                pdk->dk_nwedges--;
                LIST_REMOVE(sc, sc_plink);
                mutex_exit(&pdk->dk_openlock);

                bufq_free(sc->sc_bufq);
                free(sc, M_DKWEDGE);
                return (ENOMEM);
        }

        /* Return the devname to the caller. */
        strlcpy(dkw->dkw_devname, device_xname(sc->sc_dev),
                sizeof(dkw->dkw_devname));

        /*
         * XXX Really ought to make the disk_attach() and the changing
         * of state to RUNNING atomic.
         */

        disk_init(&sc->sc_dk, device_xname(sc->sc_dev), NULL);
        dkgetproperties(&sc->sc_dk, dkw);
        disk_attach(&sc->sc_dk);

        /* Disk wedge is ready for use! */
        sc->sc_state = DKW_STATE_RUNNING;

        /* Announce our arrival. */
        aprint_normal("%s at %s: %s\n", device_xname(sc->sc_dev), pdk->dk_name,
            sc->sc_wname);      /* XXX Unicode */
        aprint_normal("%s: %"PRIu64" blocks at %"PRId64", type: %s\n",
            device_xname(sc->sc_dev), sc->sc_size, sc->sc_offset, sc->sc_ptype);

        return (0);
}

/*
 * dkwedge_find:
 *
 *      Lookup a disk wedge based on the provided information.
 *      NOTE: We look up the wedge based on the wedge devname,
 *      not wname.
 *
 *      Return NULL if the wedge is not found, otherwise return
 *      the wedge's softc.  Assign the wedge's unit number to unitp
 *      if unitp is not NULL.
 */
static struct dkwedge_softc *
dkwedge_find(struct dkwedge_info *dkw, u_int *unitp)
{
        struct dkwedge_softc *sc = NULL;
        u_int unit;

        /* Find our softc. */
        dkw->dkw_devname[sizeof(dkw->dkw_devname) - 1] = '\0';
        rw_enter(&dkwedges_lock, RW_READER);
        for (unit = 0; unit < ndkwedges; unit++) {
                if ((sc = dkwedges[unit]) != NULL &&
                    strcmp(device_xname(sc->sc_dev), dkw->dkw_devname) == 0 &&
                    strcmp(sc->sc_parent->dk_name, dkw->dkw_parent) == 0) {
                        break;
                }
        }
        rw_exit(&dkwedges_lock);
        if (unit == ndkwedges)
                return NULL;

        if (unitp != NULL)
                *unitp = unit;

        return sc;
}

/*
 * dkwedge_del:         [exported function]
 *
 *      Delete a disk wedge based on the provided information.
 *      NOTE: We look up the wedge based on the wedge devname,
 *      not wname.
 */
int
dkwedge_del(struct dkwedge_info *dkw)
{
        struct dkwedge_softc *sc = NULL;

        /* Find our softc. */
        if ((sc = dkwedge_find(dkw, NULL)) == NULL)
                return (ESRCH);

        return config_detach(sc->sc_dev, DETACH_FORCE | DETACH_QUIET);
}

static int
dkwedge_begindetach(struct dkwedge_softc *sc, int flags)
{
        struct disk *dk = &sc->sc_dk;
        int rc;

        rc = 0;
        mutex_enter(&dk->dk_openlock);
        mutex_enter(&sc->sc_parent->dk_rawlock);
        if (dk->dk_openmask == 0)
                ;       /* nothing to do */
        else if ((flags & DETACH_FORCE) == 0)
                rc = EBUSY;
        else
                rc = dklastclose(sc);
        mutex_exit(&sc->sc_parent->dk_rawlock);
        mutex_exit(&dk->dk_openlock);

        return rc;
}

/*
 * dkwedge_detach:
 *
 *      Autoconfiguration detach function for pseudo-device glue.
 */
static int
dkwedge_detach(device_t self, int flags)
{
        struct dkwedge_softc *sc = NULL;
        u_int unit;
        int bmaj, cmaj, rc, s;

        rw_enter(&dkwedges_lock, RW_WRITER);
        for (unit = 0; unit < ndkwedges; unit++) {
                if ((sc = dkwedges[unit]) != NULL && sc->sc_dev == self)
                        break;
        }
        if (unit == ndkwedges)
                rc = ENXIO;
        else if ((rc = dkwedge_begindetach(sc, flags)) == 0) {
                /* Mark the wedge as dying. */
                sc->sc_state = DKW_STATE_DYING;
        }
        rw_exit(&dkwedges_lock);

        if (rc != 0)
                return rc;

        pmf_device_deregister(self);

        /* Locate the wedge major numbers. */
        bmaj = bdevsw_lookup_major(&dk_bdevsw);
        cmaj = cdevsw_lookup_major(&dk_cdevsw);

        /* Kill any pending restart. */
        callout_stop(&sc->sc_restart_ch);

        /*
         * dkstart() will kill any queued buffers now that the
         * state of the wedge is not RUNNING.  Once we've done
         * that, wait for any other pending I/O to complete.
         */
        s = splbio();
        dkstart(sc);
        dkwedge_wait_drain(sc);
        splx(s);

        /* Nuke the vnodes for any open instances. */
        vdevgone(bmaj, unit, unit, VBLK);
        vdevgone(cmaj, unit, unit, VCHR);

        /* Clean up the parent. */
        mutex_enter(&sc->sc_dk.dk_openlock);
        mutex_enter(&sc->sc_parent->dk_rawlock);
        if (sc->sc_dk.dk_openmask) {
                if (sc->sc_parent->dk_rawopens-- == 1) {
                        KASSERT(sc->sc_parent->dk_rawvp != NULL);
                        (void) vn_close(sc->sc_parent->dk_rawvp, FREAD | FWRITE,
                            NOCRED);
                        sc->sc_parent->dk_rawvp = NULL;
                }
                sc->sc_dk.dk_openmask = 0;
        }
        mutex_exit(&sc->sc_parent->dk_rawlock);
        mutex_exit(&sc->sc_dk.dk_openlock);

        /* Announce our departure. */
        aprint_normal("%s at %s (%s) deleted\n", device_xname(sc->sc_dev),
            sc->sc_parent->dk_name,
            sc->sc_wname);      /* XXX Unicode */

        mutex_enter(&sc->sc_parent->dk_openlock);
        sc->sc_parent->dk_nwedges--;
        LIST_REMOVE(sc, sc_plink);
        mutex_exit(&sc->sc_parent->dk_openlock);

        /* Delete our buffer queue. */
        bufq_free(sc->sc_bufq);

        /* Detach from the disk list. */
        disk_detach(&sc->sc_dk);
        disk_destroy(&sc->sc_dk);

        /* Poof. */
        rw_enter(&dkwedges_lock, RW_WRITER);
        dkwedges[unit] = NULL;
        sc->sc_state = DKW_STATE_DEAD;
        rw_exit(&dkwedges_lock);

        free(sc, M_DKWEDGE);

        return 0;
}

/*
 * dkwedge_delall:      [exported function]
 *
 *      Delete all of the wedges on the specified disk.  Used when
 *      a disk is being detached.
 */
void
dkwedge_delall(struct disk *pdk)
{
        struct dkwedge_info dkw;
        struct dkwedge_softc *sc;

        for (;;) {
                mutex_enter(&pdk->dk_openlock);
                if ((sc = LIST_FIRST(&pdk->dk_wedges)) == NULL) {
                        KASSERT(pdk->dk_nwedges == 0);
                        mutex_exit(&pdk->dk_openlock);
                        return;
                }
                strcpy(dkw.dkw_parent, pdk->dk_name);
                strlcpy(dkw.dkw_devname, device_xname(sc->sc_dev),
                        sizeof(dkw.dkw_devname));
                mutex_exit(&pdk->dk_openlock);
                (void) dkwedge_del(&dkw);
        }
}

/*
 * dkwedge_list:        [exported function]
 *
 *      List all of the wedges on a particular disk.
 *      If p == NULL, the buffer is in kernel space.  Otherwise, it is
 *      in user space of the specified process.
 */
int
dkwedge_list(struct disk *pdk, struct dkwedge_list *dkwl, struct lwp *l)
{
        struct uio uio;
        struct iovec iov;
        struct dkwedge_softc *sc;
        struct dkwedge_info dkw;
        int error = 0;

        iov.iov_base = dkwl->dkwl_buf;
        iov.iov_len = dkwl->dkwl_bufsize;

        uio.uio_iov = &iov;
        uio.uio_iovcnt = 1;
        uio.uio_offset = 0;
        uio.uio_resid = dkwl->dkwl_bufsize;
        uio.uio_rw = UIO_READ;
        KASSERT(l == curlwp);
        uio.uio_vmspace = l->l_proc->p_vmspace;

        dkwl->dkwl_ncopied = 0;

        mutex_enter(&pdk->dk_openlock);
        LIST_FOREACH(sc, &pdk->dk_wedges, sc_plink) {
                if (uio.uio_resid < sizeof(dkw))
                        break;

                if (sc->sc_state != DKW_STATE_RUNNING)
                        continue;

                strlcpy(dkw.dkw_devname, device_xname(sc->sc_dev),
                        sizeof(dkw.dkw_devname));
                memcpy(dkw.dkw_wname, sc->sc_wname, sizeof(dkw.dkw_wname));
                dkw.dkw_wname[sizeof(dkw.dkw_wname) - 1] = '\0';
                strcpy(dkw.dkw_parent, sc->sc_parent->dk_name);
                dkw.dkw_offset = sc->sc_offset;
                dkw.dkw_size = sc->sc_size;
                strcpy(dkw.dkw_ptype, sc->sc_ptype);

                error = uiomove(&dkw, sizeof(dkw), &uio);
                if (error)
                        break;
                dkwl->dkwl_ncopied++;
        }
        dkwl->dkwl_nwedges = pdk->dk_nwedges;
        mutex_exit(&pdk->dk_openlock);

        return (error);
}

device_t
dkwedge_find_by_wname(const char *wname)
{
        device_t dv = NULL;
        struct dkwedge_softc *sc;
        int i;

        rw_enter(&dkwedges_lock, RW_WRITER);
        for (i = 0; i < ndkwedges; i++) {
                if ((sc = dkwedges[i]) == NULL)
                        continue;
                if (strcmp(sc->sc_wname, wname) == 0) {
                        if (dv != NULL) {
                                printf(
                                    "WARNING: double match for wedge name %s "
                                    "(%s, %s)\n", wname, device_xname(dv),
                                    device_xname(sc->sc_dev));
                                continue;
                        }
                        dv = sc->sc_dev;
                }
        }
        rw_exit(&dkwedges_lock);
        return dv;
}

void
dkwedge_print_wnames(void)
{
        struct dkwedge_softc *sc;
        int i;

        rw_enter(&dkwedges_lock, RW_WRITER);
        for (i = 0; i < ndkwedges; i++) {
                if ((sc = dkwedges[i]) == NULL)
                        continue;
                printf(" wedge:%s", sc->sc_wname);
        }
        rw_exit(&dkwedges_lock);
}

/*
 * dkwedge_set_bootwedge
 *
 *      Set the booted_wedge global based on the specified parent name
 *      and offset/length.
 */
void
dkwedge_set_bootwedge(device_t parent, daddr_t startblk, uint64_t nblks)
{
        struct dkwedge_softc *sc;
        int i;

        rw_enter(&dkwedges_lock, RW_WRITER);
        for (i = 0; i < ndkwedges; i++) {
                if ((sc = dkwedges[i]) == NULL)
                        continue;
                if (strcmp(sc->sc_parent->dk_name, device_xname(parent)) == 0 &&
                    sc->sc_offset == startblk &&
                    sc->sc_size == nblks) {
                        if (booted_wedge) {
                                printf("WARNING: double match for boot wedge "
                                    "(%s, %s)\n",
                                    device_xname(booted_wedge),
                                    device_xname(sc->sc_dev));
                                continue;
                        }
                        booted_device = parent;
                        booted_wedge = sc->sc_dev;
                        booted_partition = 0;
                }
        }
        /*
         * XXX What if we don't find one?  Should we create a special
         * XXX root wedge?
         */
        rw_exit(&dkwedges_lock);
}

/*
 * We need a dummy object to stuff into the dkwedge discovery method link
 * set to ensure that there is always at least one object in the set.
 */
static struct dkwedge_discovery_method dummy_discovery_method;
__link_set_add_bss(dkwedge_methods, dummy_discovery_method);

/*
 * dkwedge_init:
 *
 *      Initialize the disk wedge subsystem.
 */
void
dkwedge_init(void)
{
        __link_set_decl(dkwedge_methods, struct dkwedge_discovery_method);
        struct dkwedge_discovery_method * const *ddmp;
        struct dkwedge_discovery_method *lddm, *ddm;

        rw_init(&dkwedges_lock);
        rw_init(&dkwedge_discovery_methods_lock);

        if (config_cfdriver_attach(&dk_cd) != 0)
                panic("dkwedge: unable to attach cfdriver");
        if (config_cfattach_attach(dk_cd.cd_name, &dk_ca) != 0)
                panic("dkwedge: unable to attach cfattach");

        rw_enter(&dkwedge_discovery_methods_lock, RW_WRITER);

        LIST_INIT(&dkwedge_discovery_methods);

        __link_set_foreach(ddmp, dkwedge_methods) {
                ddm = *ddmp;
                if (ddm == &dummy_discovery_method)
                        continue;
                if (LIST_EMPTY(&dkwedge_discovery_methods)) {
                        LIST_INSERT_HEAD(&dkwedge_discovery_methods,
                                         ddm, ddm_list);
                        continue;
                }
                LIST_FOREACH(lddm, &dkwedge_discovery_methods, ddm_list) {
                        if (ddm->ddm_priority == lddm->ddm_priority) {
                                aprint_error("dk-method-%s: method \"%s\" "
                                    "already exists at priority %d\n",
                                    ddm->ddm_name, lddm->ddm_name,
                                    lddm->ddm_priority);
                                /* Not inserted. */
                                break;
                        }
                        if (ddm->ddm_priority < lddm->ddm_priority) {
                                /* Higher priority; insert before. */
                                LIST_INSERT_BEFORE(lddm, ddm, ddm_list);
                                break;
                        }
                        if (LIST_NEXT(lddm, ddm_list) == NULL) {
                                /* Last one; insert after. */
                                KASSERT(lddm->ddm_priority < ddm->ddm_priority);
                                LIST_INSERT_AFTER(lddm, ddm, ddm_list);
                                break;
                        }
                }
        }

        rw_exit(&dkwedge_discovery_methods_lock);
}

#ifdef DKWEDGE_AUTODISCOVER
int     dkwedge_autodiscover = 1;
#else
int     dkwedge_autodiscover = 0;
#endif

/*
 * dkwedge_discover:    [exported function]
 *
 *      Discover the wedges on a newly attached disk.
 */
void
dkwedge_discover(struct disk *pdk)
{
        struct dkwedge_discovery_method *ddm;
        struct vnode *vp;
        int error;
        dev_t pdev;

        /*
         * Require people playing with wedges to enable this explicitly.
         */
        if (dkwedge_autodiscover == 0)
                return;

        rw_enter(&dkwedge_discovery_methods_lock, RW_READER);

        error = dkwedge_compute_pdev(pdk->dk_name, &pdev);
        if (error) {
                aprint_error("%s: unable to compute pdev, error = %d\n",
                    pdk->dk_name, error);
                goto out;
        }

        error = bdevvp(pdev, &vp);
        if (error) {
                aprint_error("%s: unable to find vnode for pdev, error = %d\n",
                    pdk->dk_name, error);
                goto out;
        }

        error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        if (error) {
                aprint_error("%s: unable to lock vnode for pdev, error = %d\n",
                    pdk->dk_name, error);
                vrele(vp);
                goto out;
        }

        error = VOP_OPEN(vp, FREAD, NOCRED);
        if (error) {
                aprint_error("%s: unable to open device, error = %d\n",
                    pdk->dk_name, error);
                vput(vp);
                goto out;
        }
        VOP_UNLOCK(vp, 0);

        /*
         * For each supported partition map type, look to see if
         * this map type exists.  If so, parse it and add the
         * corresponding wedges.
         */
        LIST_FOREACH(ddm, &dkwedge_discovery_methods, ddm_list) {
                error = (*ddm->ddm_discover)(pdk, vp);
                if (error == 0) {
                        /* Successfully created wedges; we're done. */
                        break;
                }
        }

        error = vn_close(vp, FREAD, NOCRED);
        if (error) {
                aprint_error("%s: unable to close device, error = %d\n",
                    pdk->dk_name, error);
                /* We'll just assume the vnode has been cleaned up. */
        }
 out:
        rw_exit(&dkwedge_discovery_methods_lock);
}

/*
 * dkwedge_read:
 *
 *      Read some data from the specified disk, used for
 *      partition discovery.
 */
int
dkwedge_read(struct disk *pdk, struct vnode *vp, daddr_t blkno,
    void *tbuf, size_t len)
{
        struct buf *bp;
        int result;

        bp = getiobuf(vp, true);

        bp->b_dev = vp->v_rdev;
        bp->b_blkno = blkno;
        bp->b_bcount = len;
        bp->b_resid = len;
        bp->b_flags = B_READ;
        bp->b_data = tbuf;
        SET(bp->b_cflags, BC_BUSY);     /* mark buffer busy */

        VOP_STRATEGY(vp, bp);
        result = biowait(bp);
        putiobuf(bp);

        return result;
}

/*
 * dkwedge_lookup:
 *
 *      Look up a dkwedge_softc based on the provided dev_t.
 */
static struct dkwedge_softc *
dkwedge_lookup(dev_t dev)
{
        int unit = minor(dev);

        if (unit >= ndkwedges)
                return (NULL);

        KASSERT(dkwedges != NULL);

        return (dkwedges[unit]);
}

/*
 * dkopen:              [devsw entry point]
 *
 *      Open a wedge.
 */
static int
dkopen(dev_t dev, int flags, int fmt, struct lwp *l)
{
        struct dkwedge_softc *sc = dkwedge_lookup(dev);
        struct vnode *vp;
        int error = 0;

        if (sc == NULL)
                return (ENODEV);

        if (sc->sc_state != DKW_STATE_RUNNING)
                return (ENXIO);

        /*
         * We go through a complicated little dance to only open the parent
         * vnode once per wedge, no matter how many times the wedge is
         * opened.  The reason?  We see one dkopen() per open call, but
         * only dkclose() on the last close.
         */
        mutex_enter(&sc->sc_dk.dk_openlock);
        mutex_enter(&sc->sc_parent->dk_rawlock);
        if (sc->sc_dk.dk_openmask == 0) {
                if (sc->sc_parent->dk_rawopens == 0) {
                        KASSERT(sc->sc_parent->dk_rawvp == NULL);
                        error = bdevvp(sc->sc_pdev, &vp);
                        if (error)
                                goto popen_fail;
                        error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                        if (error) {
                                vrele(vp);
                                goto popen_fail;
                        }
                        error = VOP_OPEN(vp, FREAD | FWRITE, NOCRED);
                        if (error) {
                                vput(vp);
                                goto popen_fail;
                        }
                        /* VOP_OPEN() doesn't do this for us. */
                        mutex_enter(&vp->v_interlock);
                        vp->v_writecount++;
                        mutex_exit(&vp->v_interlock);
                        VOP_UNLOCK(vp, 0);
                        sc->sc_parent->dk_rawvp = vp;
                }
                sc->sc_parent->dk_rawopens++;
        }
        if (fmt == S_IFCHR)
                sc->sc_dk.dk_copenmask |= 1;
        else
                sc->sc_dk.dk_bopenmask |= 1;
        sc->sc_dk.dk_openmask =
            sc->sc_dk.dk_copenmask | sc->sc_dk.dk_bopenmask;

 popen_fail:
        mutex_exit(&sc->sc_parent->dk_rawlock);
        mutex_exit(&sc->sc_dk.dk_openlock);
        return (error);
}

/*
 * Caller must hold sc->sc_dk.dk_openlock and sc->sc_parent->dk_rawlock.
 */
static int
dklastclose(struct dkwedge_softc *sc)
{
        int error = 0;

        if (sc->sc_parent->dk_rawopens-- == 1) {
                KASSERT(sc->sc_parent->dk_rawvp != NULL);
                error = vn_close(sc->sc_parent->dk_rawvp,
                    FREAD | FWRITE, NOCRED);
                sc->sc_parent->dk_rawvp = NULL;
        }
        return error;
}

/*
 * dkclose:             [devsw entry point]
 *
 *      Close a wedge.
 */
static int
dkclose(dev_t dev, int flags, int fmt, struct lwp *l)
{
        struct dkwedge_softc *sc = dkwedge_lookup(dev);
        int error = 0;

        KASSERT(sc->sc_dk.dk_openmask != 0);

        mutex_enter(&sc->sc_dk.dk_openlock);
        mutex_enter(&sc->sc_parent->dk_rawlock);

        if (fmt == S_IFCHR)
                sc->sc_dk.dk_copenmask &= ~1;
        else
                sc->sc_dk.dk_bopenmask &= ~1;
        sc->sc_dk.dk_openmask =
            sc->sc_dk.dk_copenmask | sc->sc_dk.dk_bopenmask;

        if (sc->sc_dk.dk_openmask == 0)
                error = dklastclose(sc);

        mutex_exit(&sc->sc_parent->dk_rawlock);
        mutex_exit(&sc->sc_dk.dk_openlock);

        return (error);
}

/*
 * dkstragegy:          [devsw entry point]
 *
 *      Perform I/O based on the wedge I/O strategy.
 */
static void
dkstrategy(struct buf *bp)
{
        struct dkwedge_softc *sc = dkwedge_lookup(bp->b_dev);
        int s;

        if (sc->sc_state != DKW_STATE_RUNNING) {
                bp->b_error = ENXIO;
                goto done;
        }

        /* If it's an empty transfer, wake up the top half now. */
        if (bp->b_bcount == 0)
                goto done;

        /* Make sure it's in-range. */
        if (bounds_check_with_mediasize(bp, DEV_BSIZE, sc->sc_size) <= 0)
                goto done;

        /* Translate it to the parent's raw LBA. */
        bp->b_rawblkno = bp->b_blkno + sc->sc_offset;

        /* Place it in the queue and start I/O on the unit. */
        s = splbio();
        sc->sc_iopend++;
        bufq_put(sc->sc_bufq, bp);
        dkstart(sc);
        splx(s);
        return;

 done:
        bp->b_resid = bp->b_bcount;
        biodone(bp);
}

/*
 * dkstart:
 *
 *      Start I/O that has been enqueued on the wedge.
 *      NOTE: Must be called at splbio()!
 */
static void
dkstart(struct dkwedge_softc *sc)
{
        struct vnode *vp;
        struct buf *bp, *nbp;

        /* Do as much work as has been enqueued. */
        while ((bp = bufq_peek(sc->sc_bufq)) != NULL) {
                if (sc->sc_state != DKW_STATE_RUNNING) {
                        (void) bufq_get(sc->sc_bufq);
                        if (sc->sc_iopend-- == 1 &&
                            (sc->sc_flags & DK_F_WAIT_DRAIN) != 0) {
                                sc->sc_flags &= ~DK_F_WAIT_DRAIN;
                                wakeup(&sc->sc_iopend);
                        }
                        bp->b_error = ENXIO;
                        bp->b_resid = bp->b_bcount;
                        biodone(bp);
                }

                /* Instrumentation. */
                disk_busy(&sc->sc_dk);

                nbp = getiobuf(sc->sc_parent->dk_rawvp, false);
                if (nbp == NULL) {
                        /*
                         * No resources to run this request; leave the
                         * buffer queued up, and schedule a timer to
                         * restart the queue in 1/2 a second.
                         */
                        disk_unbusy(&sc->sc_dk, 0, bp->b_flags & B_READ);
                        callout_schedule(&sc->sc_restart_ch, hz / 2);
                        return;
                }

                (void) bufq_get(sc->sc_bufq);

                nbp->b_data = bp->b_data;
                nbp->b_flags = bp->b_flags;
                nbp->b_oflags = bp->b_oflags;
                nbp->b_cflags = bp->b_cflags;
                nbp->b_iodone = dkiodone;
                nbp->b_proc = bp->b_proc;
                nbp->b_blkno = bp->b_rawblkno;
                nbp->b_dev = sc->sc_parent->dk_rawvp->v_rdev;
                nbp->b_bcount = bp->b_bcount;
                nbp->b_private = bp;
                BIO_COPYPRIO(nbp, bp);

                vp = nbp->b_vp;
                if ((nbp->b_flags & B_READ) == 0) {
                        mutex_enter(&vp->v_interlock);
                        vp->v_numoutput++;
                        mutex_exit(&vp->v_interlock);
                }
                VOP_STRATEGY(vp, nbp);
        }
}

/*
 * dkiodone:
 *
 *      I/O to a wedge has completed; alert the top half.
 *      NOTE: Must be called at splbio()!
 */
static void
dkiodone(struct buf *bp)
{
        struct buf *obp = bp->b_private;
        struct dkwedge_softc *sc = dkwedge_lookup(obp->b_dev);

        if (bp->b_error != 0)
                obp->b_error = bp->b_error;
        obp->b_resid = bp->b_resid;
        putiobuf(bp);

        if (sc->sc_iopend-- == 1 && (sc->sc_flags & DK_F_WAIT_DRAIN) != 0) {
                sc->sc_flags &= ~DK_F_WAIT_DRAIN;
                wakeup(&sc->sc_iopend);
        }

        disk_unbusy(&sc->sc_dk, obp->b_bcount - obp->b_resid,
            obp->b_flags & B_READ);

        biodone(obp);

        /* Kick the queue in case there is more work we can do. */
        dkstart(sc);
}

/*
 * dkrestart:
 *
 *      Restart the work queue after it was stalled due to
 *      a resource shortage.  Invoked via a callout.
 */
static void
dkrestart(void *v)
{
        struct dkwedge_softc *sc = v;
        int s;

        s = splbio();
        dkstart(sc);
        splx(s);
}

/*
 * dkminphys:
 *
 *      Call parent's minphys function.
 */
static void
dkminphys(struct buf *bp)
{
        struct dkwedge_softc *sc = dkwedge_lookup(bp->b_dev);
        dev_t dev;

        dev = bp->b_dev;
        bp->b_dev = sc->sc_pdev;
        (*sc->sc_parent->dk_driver->d_minphys)(bp);
        bp->b_dev = dev;
}

/*
 * dkread:              [devsw entry point]
 *
 *      Read from a wedge.
 */
static int
dkread(dev_t dev, struct uio *uio, int flags)
{
        struct dkwedge_softc *sc = dkwedge_lookup(dev);

        if (sc->sc_state != DKW_STATE_RUNNING)
                return (ENXIO);

        return (physio(dkstrategy, NULL, dev, B_READ, dkminphys, uio));
}

/*
 * dkwrite:             [devsw entry point]
 *
 *      Write to a wedge.
 */
static int
dkwrite(dev_t dev, struct uio *uio, int flags)
{
        struct dkwedge_softc *sc = dkwedge_lookup(dev);

        if (sc->sc_state != DKW_STATE_RUNNING)
                return (ENXIO);

        return (physio(dkstrategy, NULL, dev, B_WRITE, dkminphys, uio));
}

/*
 * dkioctl:             [devsw entry point]
 *
 *      Perform an ioctl request on a wedge.
 */
static int
dkioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
{
        struct dkwedge_softc *sc = dkwedge_lookup(dev);
        int error = 0;

        if (sc->sc_state != DKW_STATE_RUNNING)
                return (ENXIO);

        error = disk_ioctl(&sc->sc_dk, cmd, data, flag, l);
        if (error != EPASSTHROUGH)
                return (error);

        error = 0;
        
        switch (cmd) {
        case DIOCCACHESYNC:
                /*
                 * XXX Do we really need to care about having a writable
                 * file descriptor here?
                 */
                if ((flag & FWRITE) == 0)
                        error = EBADF;
                else
                        error = VOP_IOCTL(sc->sc_parent->dk_rawvp,
                                          cmd, data, flag,
                                          l != NULL ? l->l_cred : NOCRED);
                break;
        case DIOCGWEDGEINFO:
            {
                struct dkwedge_info *dkw = (void *) data;

                strlcpy(dkw->dkw_devname, device_xname(sc->sc_dev),
                        sizeof(dkw->dkw_devname));
                memcpy(dkw->dkw_wname, sc->sc_wname, sizeof(dkw->dkw_wname));
                dkw->dkw_wname[sizeof(dkw->dkw_wname) - 1] = '\0';
                strcpy(dkw->dkw_parent, sc->sc_parent->dk_name);
                dkw->dkw_offset = sc->sc_offset;
                dkw->dkw_size = sc->sc_size;
                strcpy(dkw->dkw_ptype, sc->sc_ptype);

                break;
            }

        default:
                error = ENOTTY;
        }

        return (error);
}

/*
 * dksize:              [devsw entry point]
 *
 *      Query the size of a wedge for the purpose of performing a dump
 *      or for swapping to.
 */
static int
dksize(dev_t dev)
{
        struct dkwedge_softc *sc = dkwedge_lookup(dev);
        int rv = -1;

        if (sc == NULL)
                return (-1);
        
        if (sc->sc_state != DKW_STATE_RUNNING)
                return (ENXIO);

        mutex_enter(&sc->sc_dk.dk_openlock);
        mutex_enter(&sc->sc_parent->dk_rawlock);

        /* Our content type is static, no need to open the device. */

        if (strcmp(sc->sc_ptype, DKW_PTYPE_SWAP) == 0) {
                /* Saturate if we are larger than INT_MAX. */
                if (sc->sc_size > INT_MAX)
                        rv = INT_MAX;
                else
                        rv = (int) sc->sc_size;
        }

        mutex_exit(&sc->sc_parent->dk_rawlock);
        mutex_exit(&sc->sc_dk.dk_openlock);

        return (rv);
}

/*
 * dkdump:              [devsw entry point]
 *
 *      Perform a crash dump to a wedge.
 */
static int
dkdump(dev_t dev, daddr_t blkno, void *va, size_t size)
{
        struct dkwedge_softc *sc = dkwedge_lookup(dev);
        const struct bdevsw *bdev;
        int rv = 0;

        if (sc == NULL)
                return (-1);
        
        if (sc->sc_state != DKW_STATE_RUNNING)
                return (ENXIO);

        mutex_enter(&sc->sc_dk.dk_openlock);
        mutex_enter(&sc->sc_parent->dk_rawlock);

        /* Our content type is static, no need to open the device. */

        if (strcmp(sc->sc_ptype, DKW_PTYPE_SWAP) != 0) {
                rv = ENXIO;
                goto out;
        }
        if (size % DEV_BSIZE != 0) {
                rv = EINVAL;
                goto out;
        }
        if (blkno + size / DEV_BSIZE > sc->sc_size) {
                printf("%s: blkno (%" PRIu64 ") + size / DEV_BSIZE (%zu) > "
                    "sc->sc_size (%" PRIu64 ")\n", __func__, blkno,
                    size / DEV_BSIZE, sc->sc_size);
                rv = EINVAL;
                goto out;
        }

        bdev = bdevsw_lookup(sc->sc_pdev);
        rv = (*bdev->d_dump)(sc->sc_pdev, blkno + sc->sc_offset, va, size);

out:
        mutex_exit(&sc->sc_parent->dk_rawlock);
        mutex_exit(&sc->sc_dk.dk_openlock);

        return rv;
}

/*
 * config glue
 */

int
config_handle_wedges(struct device *dv, int par)
{
        struct dkwedge_list wl;
        struct dkwedge_info *wi;
        struct vnode *vn;
        char diskname[16];
        int i, error;

        if ((vn = opendisk(dv)) == NULL)
                return -1;

        wl.dkwl_bufsize = sizeof(*wi) * 16;
        wl.dkwl_buf = wi = malloc(wl.dkwl_bufsize, M_TEMP, M_WAITOK);

        error = VOP_IOCTL(vn, DIOCLWEDGES, &wl, FREAD, NOCRED);
        VOP_CLOSE(vn, FREAD, NOCRED);
        vput(vn);
        if (error) {
#ifdef DEBUG_WEDGE
                printf("%s: List wedges returned %d\n",
                    device_xname(dv), error);
#endif
                free(wi, M_TEMP);
                return -1;
        }

#ifdef DEBUG_WEDGE
        printf("%s: Returned %u(%u) wedges\n", device_xname(dv),
            wl.dkwl_nwedges, wl.dkwl_ncopied);
#endif
        snprintf(diskname, sizeof(diskname), "%s%c", device_xname(dv),
            par + 'a');

        for (i = 0; i < wl.dkwl_ncopied; i++) {
#ifdef DEBUG_WEDGE
                printf("%s: Looking for %s in %s\n", 
                    device_xname(dv), diskname, wi[i].dkw_wname);
#endif
                if (strcmp(wi[i].dkw_wname, diskname) == 0)
                        break;
        }

        if (i == wl.dkwl_ncopied) {
#ifdef DEBUG_WEDGE
                printf("%s: Cannot find wedge with parent %s\n",
                    device_xname(dv), diskname);
#endif
                free(wi, M_TEMP);
                return -1;
        }

#ifdef DEBUG_WEDGE
        printf("%s: Setting boot wedge %s (%s) at %llu %llu\n", 
                device_xname(dv), wi[i].dkw_devname, wi[i].dkw_wname,
                (unsigned long long)wi[i].dkw_offset,
                (unsigned long long)wi[i].dkw_size);
#endif
        dkwedge_set_bootwedge(dv, wi[i].dkw_offset, wi[i].dkw_size);
        free(wi, M_TEMP);
        return 0;
}