9423 loader: zfs_bootfs() needs to use config pool txg for boot device

[unleashed.git] / usr / src / boot / sys / boot / zfs / zfs.c

/*
 * Copyright (c) 2007 Doug Rabson
 * All rights reserved.
 *
 * 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 AUTHOR 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 AUTHOR 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>

/*
 *      Stand-alone file reading package.
 */

#include <sys/disk.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/queue.h>
#include <part.h>
#include <stddef.h>
#include <stdarg.h>
#include <string.h>
#include <stand.h>
#include <bootstrap.h>

#include "libzfs.h"

#include "zfsimpl.c"

/* Define the range of indexes to be populated with ZFS Boot Environments */
#define         ZFS_BE_FIRST    4
#define         ZFS_BE_LAST     8

static int      zfs_open(const char *path, struct open_file *f);
static int      zfs_close(struct open_file *f);
static int      zfs_read(struct open_file *f, void *buf, size_t size, size_t *resid);
static off_t    zfs_seek(struct open_file *f, off_t offset, int where);
static int      zfs_stat(struct open_file *f, struct stat *sb);
static int      zfs_readdir(struct open_file *f, struct dirent *d);

struct devsw zfs_dev;

struct fs_ops zfs_fsops = {
        "zfs",
        zfs_open,
        zfs_close,
        zfs_read,
        null_write,
        zfs_seek,
        zfs_stat,
        zfs_readdir
};

/*
 * In-core open file.
 */
struct file {
        off_t           f_seekp;        /* seek pointer */
        dnode_phys_t    f_dnode;
        uint64_t        f_zap_type;     /* zap type for readdir */
        uint64_t        f_num_leafs;    /* number of fzap leaf blocks */
        zap_leaf_phys_t *f_zap_leaf;    /* zap leaf buffer */
};

#ifdef __FreeBSD__
static int      zfs_env_index;
static int      zfs_env_count;
#endif

SLIST_HEAD(zfs_be_list, zfs_be_entry) zfs_be_head = SLIST_HEAD_INITIALIZER(zfs_be_head);
struct zfs_be_list *zfs_be_headp;
struct zfs_be_entry {
        const char *name;
        SLIST_ENTRY(zfs_be_entry) entries;
} *zfs_be, *zfs_be_tmp;

/*
 * Open a file.
 */
static int
zfs_open(const char *upath, struct open_file *f)
{
        struct zfsmount *mount = (struct zfsmount *)f->f_devdata;
        struct file *fp;
        int rc;

        if (f->f_dev != &zfs_dev)
                return (EINVAL);

        /* allocate file system specific data structure */
        fp = malloc(sizeof(struct file));
        bzero(fp, sizeof(struct file));
        f->f_fsdata = (void *)fp;

        rc = zfs_lookup(mount, upath, &fp->f_dnode);
        fp->f_seekp = 0;
        if (rc) {
                f->f_fsdata = NULL;
                free(fp);
        }
        return (rc);
}

static int
zfs_close(struct open_file *f)
{
        struct file *fp = (struct file *)f->f_fsdata;

        dnode_cache_obj = 0;
        f->f_fsdata = (void *)0;
        if (fp == (struct file *)0)
                return (0);

        free(fp);
        return (0);
}

/*
 * Copy a portion of a file into kernel memory.
 * Cross block boundaries when necessary.
 */
static int
zfs_read(struct open_file *f, void *start, size_t size, size_t *resid   /* out */)
{
        const spa_t *spa = ((struct zfsmount *)f->f_devdata)->spa;
        struct file *fp = (struct file *)f->f_fsdata;
        struct stat sb;
        size_t n;
        int rc;

        rc = zfs_stat(f, &sb);
        if (rc)
                return (rc);
        n = size;
        if (fp->f_seekp + n > sb.st_size)
                n = sb.st_size - fp->f_seekp;

        rc = dnode_read(spa, &fp->f_dnode, fp->f_seekp, start, n);
        if (rc)
                return (rc);

        if (0) {
            int i;
            for (i = 0; i < n; i++)
                putchar(((char*) start)[i]);
        }
        fp->f_seekp += n;
        if (resid)
                *resid = size - n;

        return (0);
}

static off_t
zfs_seek(struct open_file *f, off_t offset, int where)
{
        struct file *fp = (struct file *)f->f_fsdata;

        switch (where) {
        case SEEK_SET:
                fp->f_seekp = offset;
                break;
        case SEEK_CUR:
                fp->f_seekp += offset;
                break;
        case SEEK_END:
            {
                struct stat sb;
                int error;

                error = zfs_stat(f, &sb);
                if (error != 0) {
                        errno = error;
                        return (-1);
                }
                fp->f_seekp = sb.st_size - offset;
                break;
            }
        default:
                errno = EINVAL;
                return (-1);
        }
        return (fp->f_seekp);
}

static int
zfs_stat(struct open_file *f, struct stat *sb)
{
        const spa_t *spa = ((struct zfsmount *)f->f_devdata)->spa;
        struct file *fp = (struct file *)f->f_fsdata;

        return (zfs_dnode_stat(spa, &fp->f_dnode, sb));
}

static int
zfs_readdir(struct open_file *f, struct dirent *d)
{
        const spa_t *spa = ((struct zfsmount *)f->f_devdata)->spa;
        struct file *fp = (struct file *)f->f_fsdata;
        mzap_ent_phys_t mze;
        struct stat sb;
        size_t bsize = fp->f_dnode.dn_datablkszsec << SPA_MINBLOCKSHIFT;
        int rc;

        rc = zfs_stat(f, &sb);
        if (rc)
                return (rc);
        if (!S_ISDIR(sb.st_mode))
                return (ENOTDIR);

        /*
         * If this is the first read, get the zap type.
         */
        if (fp->f_seekp == 0) {
                rc = dnode_read(spa, &fp->f_dnode,
                                0, &fp->f_zap_type, sizeof(fp->f_zap_type));
                if (rc)
                        return (rc);

                if (fp->f_zap_type == ZBT_MICRO) {
                        fp->f_seekp = offsetof(mzap_phys_t, mz_chunk);
                } else {
                        rc = dnode_read(spa, &fp->f_dnode,
                                        offsetof(zap_phys_t, zap_num_leafs),
                                        &fp->f_num_leafs,
                                        sizeof(fp->f_num_leafs));
                        if (rc)
                                return (rc);

                        fp->f_seekp = bsize;
                        fp->f_zap_leaf = (zap_leaf_phys_t *)malloc(bsize);
                        rc = dnode_read(spa, &fp->f_dnode,
                                        fp->f_seekp,
                                        fp->f_zap_leaf,
                                        bsize);
                        if (rc)
                                return (rc);
                }
        }

        if (fp->f_zap_type == ZBT_MICRO) {
        mzap_next:
                if (fp->f_seekp >= bsize)
                        return (ENOENT);

                rc = dnode_read(spa, &fp->f_dnode,
                                fp->f_seekp, &mze, sizeof(mze));
                if (rc)
                        return (rc);
                fp->f_seekp += sizeof(mze);

                if (!mze.mze_name[0])
                        goto mzap_next;

                d->d_fileno = ZFS_DIRENT_OBJ(mze.mze_value);
                d->d_type = ZFS_DIRENT_TYPE(mze.mze_value);
                strcpy(d->d_name, mze.mze_name);
                d->d_namlen = strlen(d->d_name);
                return (0);
        } else {
                zap_leaf_t zl;
                zap_leaf_chunk_t *zc, *nc;
                int chunk;
                size_t namelen;
                char *p;
                uint64_t value;

                /*
                 * Initialise this so we can use the ZAP size
                 * calculating macros.
                 */
                zl.l_bs = ilog2(bsize);
                zl.l_phys = fp->f_zap_leaf;

                /*
                 * Figure out which chunk we are currently looking at
                 * and consider seeking to the next leaf. We use the
                 * low bits of f_seekp as a simple chunk index.
                 */
        fzap_next:
                chunk = fp->f_seekp & (bsize - 1);
                if (chunk == ZAP_LEAF_NUMCHUNKS(&zl)) {
                        fp->f_seekp = (fp->f_seekp & ~(bsize - 1)) + bsize;
                        chunk = 0;

                        /*
                         * Check for EOF and read the new leaf.
                         */
                        if (fp->f_seekp >= bsize * fp->f_num_leafs)
                                return (ENOENT);

                        rc = dnode_read(spa, &fp->f_dnode,
                                        fp->f_seekp,
                                        fp->f_zap_leaf,
                                        bsize);
                        if (rc)
                                return (rc);
                }

                zc = &ZAP_LEAF_CHUNK(&zl, chunk);
                fp->f_seekp++;
                if (zc->l_entry.le_type != ZAP_CHUNK_ENTRY)
                        goto fzap_next;

                namelen = zc->l_entry.le_name_numints;
                if (namelen > sizeof(d->d_name))
                        namelen = sizeof(d->d_name);

                /*
                 * Paste the name back together.
                 */
                nc = &ZAP_LEAF_CHUNK(&zl, zc->l_entry.le_name_chunk);
                p = d->d_name;
                while (namelen > 0) {
                        int len;
                        len = namelen;
                        if (len > ZAP_LEAF_ARRAY_BYTES)
                                len = ZAP_LEAF_ARRAY_BYTES;
                        memcpy(p, nc->l_array.la_array, len);
                        p += len;
                        namelen -= len;
                        nc = &ZAP_LEAF_CHUNK(&zl, nc->l_array.la_next);
                }
                d->d_name[sizeof(d->d_name) - 1] = 0;

                /*
                 * Assume the first eight bytes of the value are
                 * a uint64_t.
                 */
                value = fzap_leaf_value(&zl, zc);

                d->d_fileno = ZFS_DIRENT_OBJ(value);
                d->d_type = ZFS_DIRENT_TYPE(value);
                d->d_namlen = strlen(d->d_name);

                return (0);
        }
}

static int
vdev_read(vdev_t *vdev, void *priv, off_t offset, void *buf, size_t bytes)
{
        int fd, ret;
        size_t res, size, remainder, rb_size, blksz;
        unsigned secsz;
        off_t off;
        char *bouncebuf, *rb_buf;

        fd = (uintptr_t) priv;
        bouncebuf = NULL;

        ret = ioctl(fd, DIOCGSECTORSIZE, &secsz);
        if (ret != 0)
                return (ret);

        off = offset / secsz;
        remainder = offset % secsz;
        if (lseek(fd, off * secsz, SEEK_SET) == -1)
                return (errno);

        rb_buf = buf;
        rb_size = bytes;
        size = roundup2(bytes + remainder, secsz);
        blksz = size;
        if (remainder != 0 || size != bytes) {
                bouncebuf = zfs_alloc(secsz);
                if (bouncebuf == NULL) {
                        printf("vdev_read: out of memory\n");
                        return (ENOMEM);
                }
                rb_buf = bouncebuf;
                blksz = rb_size - remainder;
        }

        while (bytes > 0) {
                res = read(fd, rb_buf, rb_size);
                if (res != rb_size) {
                        ret = EIO;
                        goto error;
                }
                if (bytes < blksz)
                        blksz = bytes;
                if (bouncebuf != NULL)
                        memcpy(buf, rb_buf + remainder, blksz);
                buf = (void *)((uintptr_t)buf + blksz);
                bytes -= blksz;
                remainder = 0;
                blksz = rb_size;
        }

        ret = 0;
error:
        if (bouncebuf != NULL)
                zfs_free(bouncebuf, secsz);
        return (ret);
}

static int
zfs_dev_init(void)
{
        spa_t *spa;
        spa_t *next;
        spa_t *prev;

        zfs_init();
        if (archsw.arch_zfs_probe == NULL)
                return (ENXIO);
        archsw.arch_zfs_probe();

        prev = NULL;
        spa = STAILQ_FIRST(&zfs_pools);
        while (spa != NULL) {
                next = STAILQ_NEXT(spa, spa_link);
                if (zfs_spa_init(spa)) {
                        if (prev == NULL)
                                STAILQ_REMOVE_HEAD(&zfs_pools, spa_link);
                        else
                                STAILQ_REMOVE_AFTER(&zfs_pools, prev, spa_link);
                } else
                        prev = spa;
                spa = next;
        }
        return (0);
}

struct zfs_probe_args {
        int             fd;
        const char      *devname;
        uint64_t        *pool_guid;
        u_int           secsz;
};

static int
zfs_diskread(void *arg, void *buf, size_t blocks, uint64_t offset)
{
        struct zfs_probe_args *ppa;

        ppa = (struct zfs_probe_args *)arg;
        return (vdev_read(NULL, (void *)(uintptr_t)ppa->fd,
            offset * ppa->secsz, buf, blocks * ppa->secsz));
}

static int
zfs_probe(int fd, uint64_t *pool_guid)
{
        spa_t *spa;
        int ret;

        ret = vdev_probe(vdev_read, (void *)(uintptr_t)fd, &spa);
        if (ret == 0 && pool_guid != NULL)
                *pool_guid = spa->spa_guid;
        return (ret);
}

static int
zfs_probe_partition(void *arg, const char *partname,
    const struct ptable_entry *part)
{
        struct zfs_probe_args *ppa, pa;
        struct ptable *table;
        char devname[32];
        int ret = 0;

        /* filter out partitions *not* used by zfs */
        switch (part->type) {
        case PART_RESERVED:     /* efi reserverd */
        case PART_VTOC_BOOT:    /* vtoc boot area */
        case PART_VTOC_SWAP:
                return (ret);
        default:
                break;
        }
        ppa = (struct zfs_probe_args *)arg;
        strncpy(devname, ppa->devname, strlen(ppa->devname) - 1);
        devname[strlen(ppa->devname) - 1] = '\0';
        sprintf(devname, "%s%s:", devname, partname);
        pa.fd = open(devname, O_RDONLY);
        if (pa.fd == -1)
                return (ret);
        ret = zfs_probe(pa.fd, ppa->pool_guid);
        if (ret == 0)
                return (ret);
        if (part->type == PART_SOLARIS2) {
                pa.devname = devname;
                pa.pool_guid = ppa->pool_guid;
                pa.secsz = ppa->secsz;
                table = ptable_open(&pa, part->end - part->start + 1,
                    ppa->secsz, zfs_diskread);
                if (table != NULL) {
                        enum ptable_type pt = ptable_gettype(table);

                        if (pt == PTABLE_VTOC8 || pt == PTABLE_VTOC)
                                ptable_iterate(table, &pa, zfs_probe_partition);
                        ptable_close(table);
                }
        }
        close(pa.fd);
        return (0);
}

int
zfs_probe_dev(const char *devname, uint64_t *pool_guid)
{
        struct ptable *table;
        struct zfs_probe_args pa;
        uint64_t mediasz;
        int ret;

        if (pool_guid)
                *pool_guid = 0;
        pa.fd = open(devname, O_RDONLY);
        if (pa.fd == -1)
                return (ENXIO);
        /* Probe the whole disk */
        ret = zfs_probe(pa.fd, pool_guid);
        if (ret == 0)
                return (0);

        /* Probe each partition */
        ret = ioctl(pa.fd, DIOCGMEDIASIZE, &mediasz);
        if (ret == 0)
                ret = ioctl(pa.fd, DIOCGSECTORSIZE, &pa.secsz);
        if (ret == 0) {
                pa.devname = devname;
                pa.pool_guid = pool_guid;
                table = ptable_open(&pa, mediasz / pa.secsz, pa.secsz,
                    zfs_diskread);
                if (table != NULL) {
                        ptable_iterate(table, &pa, zfs_probe_partition);
                        ptable_close(table);
                }
        }
        close(pa.fd);
        if (pool_guid && *pool_guid == 0)
                ret = ENXIO;
        return (ret);
}

/*
 * Print information about ZFS pools
 */
static int
zfs_dev_print(int verbose)
{
        spa_t *spa;
        char line[80];
        int ret = 0;

        if (STAILQ_EMPTY(&zfs_pools))
                return (0);

        printf("%s devices:", zfs_dev.dv_name);
        if ((ret = pager_output("\n")) != 0)
                return (ret);

        if (verbose) {
                return (spa_all_status());
        }
        STAILQ_FOREACH(spa, &zfs_pools, spa_link) {
                sprintf(line, "    zfs:%s\n", spa->spa_name);
                ret = pager_output(line);
                if (ret != 0)
                        break;
        }
        return (ret);
}

/*
 * Attempt to open the pool described by (dev) for use by (f).
 */
static int
zfs_dev_open(struct open_file *f, ...)
{
        va_list         args;
        struct zfs_devdesc      *dev;
        struct zfsmount *mount;
        spa_t           *spa;
        int             rv;

        va_start(args, f);
        dev = va_arg(args, struct zfs_devdesc *);
        va_end(args);

        if (dev->pool_guid == 0)
                spa = STAILQ_FIRST(&zfs_pools);
        else
                spa = spa_find_by_guid(dev->pool_guid);
        if (!spa)
                return (ENXIO);
        mount = malloc(sizeof(*mount));
        rv = zfs_mount(spa, dev->root_guid, mount);
        if (rv != 0) {
                free(mount);
                return (rv);
        }
        if (mount->objset.os_type != DMU_OST_ZFS) {
                printf("Unexpected object set type %ju\n",
                    (uintmax_t)mount->objset.os_type);
                free(mount);
                return (EIO);
        }
        f->f_devdata = mount;
        free(dev);
        return (0);
}

static int
zfs_dev_close(struct open_file *f)
{

        free(f->f_devdata);
        f->f_devdata = NULL;
        return (0);
}

static int
zfs_dev_strategy(void *devdata, int rw, daddr_t dblk, size_t size,
    char *buf, size_t *rsize)
{

        return (ENOSYS);
}

struct devsw zfs_dev = {
        .dv_name = "zfs",
        .dv_type = DEVT_ZFS,
        .dv_init = zfs_dev_init,
        .dv_strategy = zfs_dev_strategy,
        .dv_open = zfs_dev_open,
        .dv_close = zfs_dev_close,
        .dv_ioctl = noioctl,
        .dv_print = zfs_dev_print,
        .dv_cleanup = NULL
};

int
zfs_parsedev(struct zfs_devdesc *dev, const char *devspec, const char **path)
{
        static char     rootname[ZFS_MAXNAMELEN];
        static char     poolname[ZFS_MAXNAMELEN];
        spa_t           *spa;
        const char      *end;
        const char      *np;
        const char      *sep;
        int             rv;

        np = devspec;
        if (*np != ':')
                return (EINVAL);
        np++;
        end = strchr(np, ':');
        if (end == NULL)
                return (EINVAL);
        sep = strchr(np, '/');
        if (sep == NULL || sep >= end)
                sep = end;
        memcpy(poolname, np, sep - np);
        poolname[sep - np] = '\0';
        if (sep < end) {
                sep++;
                memcpy(rootname, sep, end - sep);
                rootname[end - sep] = '\0';
        }
        else
                rootname[0] = '\0';

        spa = spa_find_by_name(poolname);
        if (!spa)
                return (ENXIO);
        dev->pool_guid = spa->spa_guid;
        rv = zfs_lookup_dataset(spa, rootname, &dev->root_guid);
        if (rv != 0)
                return (rv);
        if (path != NULL)
                *path = (*end == '\0') ? end : end + 1;
        dev->d_dev = &zfs_dev;
        dev->d_type = zfs_dev.dv_type;
        return (0);
}

char *
zfs_bootfs(void *zdev)
{
        static char             rootname[ZFS_MAXNAMELEN];
        static char             buf[2 * ZFS_MAXNAMELEN];
        struct zfs_devdesc      *dev = (struct zfs_devdesc *)zdev;
        uint64_t                objnum;
        spa_t                   *spa;
        int                     n;

        buf[0] = '\0';
        if (dev->d_type != DEVT_ZFS)
                return (buf);

        spa = spa_find_by_guid(dev->pool_guid);
        if (spa == NULL) {
                printf("ZFS: can't find pool by guid\n");
                return (buf);
        }
        if (zfs_rlookup(spa, dev->root_guid, rootname)) {
                printf("ZFS: can't find filesystem by guid\n");
                return (buf);
        }
        if (zfs_lookup_dataset(spa, rootname, &objnum)) {
                printf("ZFS: can't find filesystem by name\n");
                return (buf);
        }

        /* Set the environment. */
        snprintf(buf, sizeof (buf), "%s/%llu", spa->spa_name,
            (unsigned long long)objnum);
        setenv("zfs-bootfs", buf, 1);
        if (spa->spa_boot_vdev->v_phys_path != NULL)
                setenv("bootpath", spa->spa_boot_vdev->v_phys_path, 1);
        if (spa->spa_boot_vdev->v_devid != NULL)
                setenv("diskdevid", spa->spa_boot_vdev->v_devid, 1);

        /*
         * Build the command line string. Once our kernel will read
         * the environment and we can stop caring about old kernels,
         * we can remove this part.
         */
        snprintf(buf, sizeof(buf), "zfs-bootfs=%s/%llu", spa->spa_name,
            (unsigned long long)objnum);
        n = strlen(buf);
        if (spa->spa_boot_vdev->v_phys_path != NULL) {
                snprintf(buf+n, sizeof (buf) - n, ",bootpath=\"%s\"",
                    spa->spa_boot_vdev->v_phys_path);
                n = strlen(buf);
        }
        if (spa->spa_boot_vdev->v_devid != NULL) {
                snprintf(buf+n, sizeof (buf) - n, ",diskdevid=\"%s\"",
                    spa->spa_boot_vdev->v_devid);
        }
        return (buf);
}

char *
zfs_fmtdev(void *vdev)
{
        static char             rootname[ZFS_MAXNAMELEN];
        static char             buf[2 * ZFS_MAXNAMELEN + 8];
        struct zfs_devdesc      *dev = (struct zfs_devdesc *)vdev;
        spa_t                   *spa;

        buf[0] = '\0';
        if (dev->d_type != DEVT_ZFS)
                return (buf);

        if (dev->pool_guid == 0) {
                spa = STAILQ_FIRST(&zfs_pools);
                dev->pool_guid = spa->spa_guid;
        } else
                spa = spa_find_by_guid(dev->pool_guid);
        if (spa == NULL) {
                printf("ZFS: can't find pool by guid\n");
                return (buf);
        }
        if (dev->root_guid == 0 && zfs_get_root(spa, &dev->root_guid)) {
                printf("ZFS: can't find root filesystem\n");
                return (buf);
        }
        if (zfs_rlookup(spa, dev->root_guid, rootname)) {
                printf("ZFS: can't find filesystem by guid\n");
                return (buf);
        }

        if (rootname[0] == '\0')
                sprintf(buf, "%s:%s:", dev->d_dev->dv_name, spa->spa_name);
        else
                sprintf(buf, "%s:%s/%s:", dev->d_dev->dv_name, spa->spa_name,
                    rootname);
        return (buf);
}

int
zfs_list(const char *name)
{
        static char     poolname[ZFS_MAXNAMELEN];
        uint64_t        objid;
        spa_t           *spa;
        const char      *dsname;
        int             len;
        int             rv;

        len = strlen(name);
        dsname = strchr(name, '/');
        if (dsname != NULL) {
                len = dsname - name;
                dsname++;
        } else
                dsname = "";
        memcpy(poolname, name, len);
        poolname[len] = '\0';

        spa = spa_find_by_name(poolname);
        if (!spa)
                return (ENXIO);
        rv = zfs_lookup_dataset(spa, dsname, &objid);
        if (rv != 0)
                return (rv);

        return (zfs_list_dataset(spa, objid));
}

#ifdef __FreeBSD__
void
init_zfs_bootenv(char *currdev)
{
        char *beroot;

        if (strlen(currdev) == 0)
                return;
        if(strncmp(currdev, "zfs:", 4) != 0)
                return;
        /* Remove the trailing : */
        currdev[strlen(currdev) - 1] = '\0';
        setenv("zfs_be_active", currdev, 1);
        setenv("zfs_be_currpage", "1", 1);
        /* Forward past zfs: */
        currdev = strchr(currdev, ':');
        currdev++;
        /* Remove the last element (current bootenv) */
        beroot = strrchr(currdev, '/');
        if (beroot != NULL)
                beroot[0] = '\0';
        beroot = currdev;
        setenv("zfs_be_root", beroot, 1);
}

int
zfs_bootenv(const char *name)
{
        static char     poolname[ZFS_MAXNAMELEN], *dsname, *root;
        char            becount[4];
        uint64_t        objid;
        spa_t           *spa;
        int             len, rv, pages, perpage, currpage;

        if (name == NULL)
                return (EINVAL);
        if ((root = getenv("zfs_be_root")) == NULL)
                return (EINVAL);

        if (strcmp(name, root) != 0) {
                if (setenv("zfs_be_root", name, 1) != 0)
                        return (ENOMEM);
        }

        SLIST_INIT(&zfs_be_head);
        zfs_env_count = 0;
        len = strlen(name);
        dsname = strchr(name, '/');
        if (dsname != NULL) {
                len = dsname - name;
                dsname++;
        } else
                dsname = "";
        memcpy(poolname, name, len);
        poolname[len] = '\0';

        spa = spa_find_by_name(poolname);
        if (!spa)
                return (ENXIO);
        rv = zfs_lookup_dataset(spa, dsname, &objid);
        if (rv != 0)
                return (rv);
        rv = zfs_callback_dataset(spa, objid, zfs_belist_add);

        /* Calculate and store the number of pages of BEs */
        perpage = (ZFS_BE_LAST - ZFS_BE_FIRST + 1);
        pages = (zfs_env_count / perpage) + ((zfs_env_count % perpage) > 0 ? 1 : 0);
        snprintf(becount, 4, "%d", pages);
        if (setenv("zfs_be_pages", becount, 1) != 0)
                return (ENOMEM);

        /* Roll over the page counter if it has exceeded the maximum */
        currpage = strtol(getenv("zfs_be_currpage"), NULL, 10);
        if (currpage > pages) {
                if (setenv("zfs_be_currpage", "1", 1) != 0)
                        return (ENOMEM);
        }

        /* Populate the menu environment variables */
        zfs_set_env();

        /* Clean up the SLIST of ZFS BEs */
        while (!SLIST_EMPTY(&zfs_be_head)) {
                zfs_be = SLIST_FIRST(&zfs_be_head);
                SLIST_REMOVE_HEAD(&zfs_be_head, entries);
                free(zfs_be);
        }

        return (rv);
}

int
zfs_belist_add(const char *name, uint64_t value __unused)
{

        /* Skip special datasets that start with a $ character */
        if (strncmp(name, "$", 1) == 0) {
                return (0);
        }
        /* Add the boot environment to the head of the SLIST */
        zfs_be = malloc(sizeof(struct zfs_be_entry));
        if (zfs_be == NULL) {
                return (ENOMEM);
        }
        zfs_be->name = name;
        SLIST_INSERT_HEAD(&zfs_be_head, zfs_be, entries);
        zfs_env_count++;

        return (0);
}

int
zfs_set_env(void)
{
        char envname[32], envval[256];
        char *beroot, *pagenum;
        int rv, page, ctr;

        beroot = getenv("zfs_be_root");
        if (beroot == NULL) {
                return (1);
        }

        pagenum = getenv("zfs_be_currpage");
        if (pagenum != NULL) {
                page = strtol(pagenum, NULL, 10);
        } else {
                page = 1;
        }

        ctr = 1;
        rv = 0;
        zfs_env_index = ZFS_BE_FIRST;
        SLIST_FOREACH_SAFE(zfs_be, &zfs_be_head, entries, zfs_be_tmp) {
                /* Skip to the requested page number */
                if (ctr <= ((ZFS_BE_LAST - ZFS_BE_FIRST + 1) * (page - 1))) {
                        ctr++;
                        continue;
                }
                
                snprintf(envname, sizeof(envname), "bootenvmenu_caption[%d]", zfs_env_index);
                snprintf(envval, sizeof(envval), "%s", zfs_be->name);
                rv = setenv(envname, envval, 1);
                if (rv != 0) {
                        break;
                }

                snprintf(envname, sizeof(envname), "bootenvansi_caption[%d]", zfs_env_index);
                rv = setenv(envname, envval, 1);
                if (rv != 0){
                        break;
                }

                snprintf(envname, sizeof(envname), "bootenvmenu_command[%d]", zfs_env_index);
                rv = setenv(envname, "set_bootenv", 1);
                if (rv != 0){
                        break;
                }

                snprintf(envname, sizeof(envname), "bootenv_root[%d]", zfs_env_index);
                snprintf(envval, sizeof(envval), "zfs:%s/%s", beroot, zfs_be->name);
                rv = setenv(envname, envval, 1);
                if (rv != 0){
                        break;
                }

                zfs_env_index++;
                if (zfs_env_index > ZFS_BE_LAST) {
                        break;
                }

        }
        
        for (; zfs_env_index <= ZFS_BE_LAST; zfs_env_index++) {
                snprintf(envname, sizeof(envname), "bootenvmenu_caption[%d]", zfs_env_index);
                (void)unsetenv(envname);
                snprintf(envname, sizeof(envname), "bootenvansi_caption[%d]", zfs_env_index);
                (void)unsetenv(envname);
                snprintf(envname, sizeof(envname), "bootenvmenu_command[%d]", zfs_env_index);
                (void)unsetenv(envname);
                snprintf(envname, sizeof(envname), "bootenv_root[%d]", zfs_env_index);
                (void)unsetenv(envname);
        }

        return (rv);
}
#endif