5518 Memory leaks in libzfs import implementation

[illumos-gate.git] / usr / src / lib / libzfs / common / libzfs_import.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 2015 Nexenta Systems, Inc.  All rights reserved.
 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2013 by Delphix. All rights reserved.
 */

/*
 * Pool import support functions.
 *
 * To import a pool, we rely on reading the configuration information from the
 * ZFS label of each device.  If we successfully read the label, then we
 * organize the configuration information in the following hierarchy:
 *
 *      pool guid -> toplevel vdev guid -> label txg
 *
 * Duplicate entries matching this same tuple will be discarded.  Once we have
 * examined every device, we pick the best label txg config for each toplevel
 * vdev.  We then arrange these toplevel vdevs into a complete pool config, and
 * update any paths that have changed.  Finally, we attempt to import the pool
 * using our derived config, and record the results.
 */

#include <ctype.h>
#include <devid.h>
#include <dirent.h>
#include <errno.h>
#include <libintl.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/vtoc.h>
#include <sys/dktp/fdisk.h>
#include <sys/efi_partition.h>
#include <thread_pool.h>

#include <sys/vdev_impl.h>

#include "libzfs.h"
#include "libzfs_impl.h"

/*
 * Intermediate structures used to gather configuration information.
 */
typedef struct config_entry {
        uint64_t                ce_txg;
        nvlist_t                *ce_config;
        struct config_entry     *ce_next;
} config_entry_t;

typedef struct vdev_entry {
        uint64_t                ve_guid;
        config_entry_t          *ve_configs;
        struct vdev_entry       *ve_next;
} vdev_entry_t;

typedef struct pool_entry {
        uint64_t                pe_guid;
        vdev_entry_t            *pe_vdevs;
        struct pool_entry       *pe_next;
} pool_entry_t;

typedef struct name_entry {
        char                    *ne_name;
        uint64_t                ne_guid;
        struct name_entry       *ne_next;
} name_entry_t;

typedef struct pool_list {
        pool_entry_t            *pools;
        name_entry_t            *names;
} pool_list_t;

static char *
get_devid(const char *path)
{
        int fd;
        ddi_devid_t devid;
        char *minor, *ret;

        if ((fd = open(path, O_RDONLY)) < 0)
                return (NULL);

        minor = NULL;
        ret = NULL;
        if (devid_get(fd, &devid) == 0) {
                if (devid_get_minor_name(fd, &minor) == 0)
                        ret = devid_str_encode(devid, minor);
                if (minor != NULL)
                        devid_str_free(minor);
                devid_free(devid);
        }
        (void) close(fd);

        return (ret);
}


/*
 * Go through and fix up any path and/or devid information for the given vdev
 * configuration.
 */
static int
fix_paths(nvlist_t *nv, name_entry_t *names)
{
        nvlist_t **child;
        uint_t c, children;
        uint64_t guid;
        name_entry_t *ne, *best;
        char *path, *devid;
        int matched;

        if (nvlist_lookup_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN,
            &child, &children) == 0) {
                for (c = 0; c < children; c++)
                        if (fix_paths(child[c], names) != 0)
                                return (-1);
                return (0);
        }

        /*
         * This is a leaf (file or disk) vdev.  In either case, go through
         * the name list and see if we find a matching guid.  If so, replace
         * the path and see if we can calculate a new devid.
         *
         * There may be multiple names associated with a particular guid, in
         * which case we have overlapping slices or multiple paths to the same
         * disk.  If this is the case, then we want to pick the path that is
         * the most similar to the original, where "most similar" is the number
         * of matching characters starting from the end of the path.  This will
         * preserve slice numbers even if the disks have been reorganized, and
         * will also catch preferred disk names if multiple paths exist.
         */
        verify(nvlist_lookup_uint64(nv, ZPOOL_CONFIG_GUID, &guid) == 0);
        if (nvlist_lookup_string(nv, ZPOOL_CONFIG_PATH, &path) != 0)
                path = NULL;

        matched = 0;
        best = NULL;
        for (ne = names; ne != NULL; ne = ne->ne_next) {
                if (ne->ne_guid == guid) {
                        const char *src, *dst;
                        int count;

                        if (path == NULL) {
                                best = ne;
                                break;
                        }

                        src = ne->ne_name + strlen(ne->ne_name) - 1;
                        dst = path + strlen(path) - 1;
                        for (count = 0; src >= ne->ne_name && dst >= path;
                            src--, dst--, count++)
                                if (*src != *dst)
                                        break;

                        /*
                         * At this point, 'count' is the number of characters
                         * matched from the end.
                         */
                        if (count > matched || best == NULL) {
                                best = ne;
                                matched = count;
                        }
                }
        }

        if (best == NULL)
                return (0);

        if (nvlist_add_string(nv, ZPOOL_CONFIG_PATH, best->ne_name) != 0)
                return (-1);

        if ((devid = get_devid(best->ne_name)) == NULL) {
                (void) nvlist_remove_all(nv, ZPOOL_CONFIG_DEVID);
        } else {
                if (nvlist_add_string(nv, ZPOOL_CONFIG_DEVID, devid) != 0) {
                        devid_str_free(devid);
                        return (-1);
                }
                devid_str_free(devid);
        }

        return (0);
}

/*
 * Add the given configuration to the list of known devices.
 */
static int
add_config(libzfs_handle_t *hdl, pool_list_t *pl, const char *path,
    nvlist_t *config)
{
        uint64_t pool_guid, vdev_guid, top_guid, txg, state;
        pool_entry_t *pe;
        vdev_entry_t *ve;
        config_entry_t *ce;
        name_entry_t *ne;

        /*
         * If this is a hot spare not currently in use or level 2 cache
         * device, add it to the list of names to translate, but don't do
         * anything else.
         */
        if (nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_STATE,
            &state) == 0 &&
            (state == POOL_STATE_SPARE || state == POOL_STATE_L2CACHE) &&
            nvlist_lookup_uint64(config, ZPOOL_CONFIG_GUID, &vdev_guid) == 0) {
                if ((ne = zfs_alloc(hdl, sizeof (name_entry_t))) == NULL)
                        return (-1);

                if ((ne->ne_name = zfs_strdup(hdl, path)) == NULL) {
                        free(ne);
                        return (-1);
                }
                ne->ne_guid = vdev_guid;
                ne->ne_next = pl->names;
                pl->names = ne;
                return (0);
        }

        /*
         * If we have a valid config but cannot read any of these fields, then
         * it means we have a half-initialized label.  In vdev_label_init()
         * we write a label with txg == 0 so that we can identify the device
         * in case the user refers to the same disk later on.  If we fail to
         * create the pool, we'll be left with a label in this state
         * which should not be considered part of a valid pool.
         */
        if (nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_GUID,
            &pool_guid) != 0 ||
            nvlist_lookup_uint64(config, ZPOOL_CONFIG_GUID,
            &vdev_guid) != 0 ||
            nvlist_lookup_uint64(config, ZPOOL_CONFIG_TOP_GUID,
            &top_guid) != 0 ||
            nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_TXG,
            &txg) != 0 || txg == 0) {
                nvlist_free(config);
                return (0);
        }

        /*
         * First, see if we know about this pool.  If not, then add it to the
         * list of known pools.
         */
        for (pe = pl->pools; pe != NULL; pe = pe->pe_next) {
                if (pe->pe_guid == pool_guid)
                        break;
        }

        if (pe == NULL) {
                if ((pe = zfs_alloc(hdl, sizeof (pool_entry_t))) == NULL) {
                        nvlist_free(config);
                        return (-1);
                }
                pe->pe_guid = pool_guid;
                pe->pe_next = pl->pools;
                pl->pools = pe;
        }

        /*
         * Second, see if we know about this toplevel vdev.  Add it if its
         * missing.
         */
        for (ve = pe->pe_vdevs; ve != NULL; ve = ve->ve_next) {
                if (ve->ve_guid == top_guid)
                        break;
        }

        if (ve == NULL) {
                if ((ve = zfs_alloc(hdl, sizeof (vdev_entry_t))) == NULL) {
                        nvlist_free(config);
                        return (-1);
                }
                ve->ve_guid = top_guid;
                ve->ve_next = pe->pe_vdevs;
                pe->pe_vdevs = ve;
        }

        /*
         * Third, see if we have a config with a matching transaction group.  If
         * so, then we do nothing.  Otherwise, add it to the list of known
         * configs.
         */
        for (ce = ve->ve_configs; ce != NULL; ce = ce->ce_next) {
                if (ce->ce_txg == txg)
                        break;
        }

        if (ce == NULL) {
                if ((ce = zfs_alloc(hdl, sizeof (config_entry_t))) == NULL) {
                        nvlist_free(config);
                        return (-1);
                }
                ce->ce_txg = txg;
                ce->ce_config = config;
                ce->ce_next = ve->ve_configs;
                ve->ve_configs = ce;
        } else {
                nvlist_free(config);
        }

        /*
         * At this point we've successfully added our config to the list of
         * known configs.  The last thing to do is add the vdev guid -> path
         * mappings so that we can fix up the configuration as necessary before
         * doing the import.
         */
        if ((ne = zfs_alloc(hdl, sizeof (name_entry_t))) == NULL)
                return (-1);

        if ((ne->ne_name = zfs_strdup(hdl, path)) == NULL) {
                free(ne);
                return (-1);
        }

        ne->ne_guid = vdev_guid;
        ne->ne_next = pl->names;
        pl->names = ne;

        return (0);
}

/*
 * Returns true if the named pool matches the given GUID.
 */
static int
pool_active(libzfs_handle_t *hdl, const char *name, uint64_t guid,
    boolean_t *isactive)
{
        zpool_handle_t *zhp;
        uint64_t theguid;

        if (zpool_open_silent(hdl, name, &zhp) != 0)
                return (-1);

        if (zhp == NULL) {
                *isactive = B_FALSE;
                return (0);
        }

        verify(nvlist_lookup_uint64(zhp->zpool_config, ZPOOL_CONFIG_POOL_GUID,
            &theguid) == 0);

        zpool_close(zhp);

        *isactive = (theguid == guid);
        return (0);
}

static nvlist_t *
refresh_config(libzfs_handle_t *hdl, nvlist_t *config)
{
        nvlist_t *nvl;
        zfs_cmd_t zc = { 0 };
        int err;

        if (zcmd_write_conf_nvlist(hdl, &zc, config) != 0)
                return (NULL);

        if (zcmd_alloc_dst_nvlist(hdl, &zc,
            zc.zc_nvlist_conf_size * 2) != 0) {
                zcmd_free_nvlists(&zc);
                return (NULL);
        }

        while ((err = ioctl(hdl->libzfs_fd, ZFS_IOC_POOL_TRYIMPORT,
            &zc)) != 0 && errno == ENOMEM) {
                if (zcmd_expand_dst_nvlist(hdl, &zc) != 0) {
                        zcmd_free_nvlists(&zc);
                        return (NULL);
                }
        }

        if (err) {
                zcmd_free_nvlists(&zc);
                return (NULL);
        }

        if (zcmd_read_dst_nvlist(hdl, &zc, &nvl) != 0) {
                zcmd_free_nvlists(&zc);
                return (NULL);
        }

        zcmd_free_nvlists(&zc);
        return (nvl);
}

/*
 * Determine if the vdev id is a hole in the namespace.
 */
boolean_t
vdev_is_hole(uint64_t *hole_array, uint_t holes, uint_t id)
{
        for (int c = 0; c < holes; c++) {

                /* Top-level is a hole */
                if (hole_array[c] == id)
                        return (B_TRUE);
        }
        return (B_FALSE);
}

/*
 * Convert our list of pools into the definitive set of configurations.  We
 * start by picking the best config for each toplevel vdev.  Once that's done,
 * we assemble the toplevel vdevs into a full config for the pool.  We make a
 * pass to fix up any incorrect paths, and then add it to the main list to
 * return to the user.
 */
static nvlist_t *
get_configs(libzfs_handle_t *hdl, pool_list_t *pl, boolean_t active_ok)
{
        pool_entry_t *pe;
        vdev_entry_t *ve;
        config_entry_t *ce;
        nvlist_t *ret = NULL, *config = NULL, *tmp, *nvtop, *nvroot;
        nvlist_t **spares, **l2cache;
        uint_t i, nspares, nl2cache;
        boolean_t config_seen;
        uint64_t best_txg;
        char *name, *hostname;
        uint64_t guid;
        uint_t children = 0;
        nvlist_t **child = NULL;
        uint_t holes;
        uint64_t *hole_array, max_id;
        uint_t c;
        boolean_t isactive;
        uint64_t hostid;
        nvlist_t *nvl;
        boolean_t found_one = B_FALSE;
        boolean_t valid_top_config = B_FALSE;

        if (nvlist_alloc(&ret, 0, 0) != 0)
                goto nomem;

        for (pe = pl->pools; pe != NULL; pe = pe->pe_next) {
                uint64_t id, max_txg = 0;

                if (nvlist_alloc(&config, NV_UNIQUE_NAME, 0) != 0)
                        goto nomem;
                config_seen = B_FALSE;

                /*
                 * Iterate over all toplevel vdevs.  Grab the pool configuration
                 * from the first one we find, and then go through the rest and
                 * add them as necessary to the 'vdevs' member of the config.
                 */
                for (ve = pe->pe_vdevs; ve != NULL; ve = ve->ve_next) {

                        /*
                         * Determine the best configuration for this vdev by
                         * selecting the config with the latest transaction
                         * group.
                         */
                        best_txg = 0;
                        for (ce = ve->ve_configs; ce != NULL;
                            ce = ce->ce_next) {

                                if (ce->ce_txg > best_txg) {
                                        tmp = ce->ce_config;
                                        best_txg = ce->ce_txg;
                                }
                        }

                        /*
                         * We rely on the fact that the max txg for the
                         * pool will contain the most up-to-date information
                         * about the valid top-levels in the vdev namespace.
                         */
                        if (best_txg > max_txg) {
                                (void) nvlist_remove(config,
                                    ZPOOL_CONFIG_VDEV_CHILDREN,
                                    DATA_TYPE_UINT64);
                                (void) nvlist_remove(config,
                                    ZPOOL_CONFIG_HOLE_ARRAY,
                                    DATA_TYPE_UINT64_ARRAY);

                                max_txg = best_txg;
                                hole_array = NULL;
                                holes = 0;
                                max_id = 0;
                                valid_top_config = B_FALSE;

                                if (nvlist_lookup_uint64(tmp,
                                    ZPOOL_CONFIG_VDEV_CHILDREN, &max_id) == 0) {
                                        verify(nvlist_add_uint64(config,
                                            ZPOOL_CONFIG_VDEV_CHILDREN,
                                            max_id) == 0);
                                        valid_top_config = B_TRUE;
                                }

                                if (nvlist_lookup_uint64_array(tmp,
                                    ZPOOL_CONFIG_HOLE_ARRAY, &hole_array,
                                    &holes) == 0) {
                                        verify(nvlist_add_uint64_array(config,
                                            ZPOOL_CONFIG_HOLE_ARRAY,
                                            hole_array, holes) == 0);
                                }
                        }

                        if (!config_seen) {
                                /*
                                 * Copy the relevant pieces of data to the pool
                                 * configuration:
                                 *
                                 *      version
                                 *      pool guid
                                 *      name
                                 *      comment (if available)
                                 *      pool state
                                 *      hostid (if available)
                                 *      hostname (if available)
                                 */
                                uint64_t state, version;
                                char *comment = NULL;

                                version = fnvlist_lookup_uint64(tmp,
                                    ZPOOL_CONFIG_VERSION);
                                fnvlist_add_uint64(config,
                                    ZPOOL_CONFIG_VERSION, version);
                                guid = fnvlist_lookup_uint64(tmp,
                                    ZPOOL_CONFIG_POOL_GUID);
                                fnvlist_add_uint64(config,
                                    ZPOOL_CONFIG_POOL_GUID, guid);
                                name = fnvlist_lookup_string(tmp,
                                    ZPOOL_CONFIG_POOL_NAME);
                                fnvlist_add_string(config,
                                    ZPOOL_CONFIG_POOL_NAME, name);

                                if (nvlist_lookup_string(tmp,
                                    ZPOOL_CONFIG_COMMENT, &comment) == 0)
                                        fnvlist_add_string(config,
                                            ZPOOL_CONFIG_COMMENT, comment);

                                state = fnvlist_lookup_uint64(tmp,
                                    ZPOOL_CONFIG_POOL_STATE);
                                fnvlist_add_uint64(config,
                                    ZPOOL_CONFIG_POOL_STATE, state);

                                hostid = 0;
                                if (nvlist_lookup_uint64(tmp,
                                    ZPOOL_CONFIG_HOSTID, &hostid) == 0) {
                                        fnvlist_add_uint64(config,
                                            ZPOOL_CONFIG_HOSTID, hostid);
                                        hostname = fnvlist_lookup_string(tmp,
                                            ZPOOL_CONFIG_HOSTNAME);
                                        fnvlist_add_string(config,
                                            ZPOOL_CONFIG_HOSTNAME, hostname);
                                }

                                config_seen = B_TRUE;
                        }

                        /*
                         * Add this top-level vdev to the child array.
                         */
                        verify(nvlist_lookup_nvlist(tmp,
                            ZPOOL_CONFIG_VDEV_TREE, &nvtop) == 0);
                        verify(nvlist_lookup_uint64(nvtop, ZPOOL_CONFIG_ID,
                            &id) == 0);

                        if (id >= children) {
                                nvlist_t **newchild;

                                newchild = zfs_alloc(hdl, (id + 1) *
                                    sizeof (nvlist_t *));
                                if (newchild == NULL)
                                        goto nomem;

                                for (c = 0; c < children; c++)
                                        newchild[c] = child[c];

                                free(child);
                                child = newchild;
                                children = id + 1;
                        }
                        if (nvlist_dup(nvtop, &child[id], 0) != 0)
                                goto nomem;

                }

                /*
                 * If we have information about all the top-levels then
                 * clean up the nvlist which we've constructed. This
                 * means removing any extraneous devices that are
                 * beyond the valid range or adding devices to the end
                 * of our array which appear to be missing.
                 */
                if (valid_top_config) {
                        if (max_id < children) {
                                for (c = max_id; c < children; c++)
                                        nvlist_free(child[c]);
                                children = max_id;
                        } else if (max_id > children) {
                                nvlist_t **newchild;

                                newchild = zfs_alloc(hdl, (max_id) *
                                    sizeof (nvlist_t *));
                                if (newchild == NULL)
                                        goto nomem;

                                for (c = 0; c < children; c++)
                                        newchild[c] = child[c];

                                free(child);
                                child = newchild;
                                children = max_id;
                        }
                }

                verify(nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_GUID,
                    &guid) == 0);

                /*
                 * The vdev namespace may contain holes as a result of
                 * device removal. We must add them back into the vdev
                 * tree before we process any missing devices.
                 */
                if (holes > 0) {
                        ASSERT(valid_top_config);

                        for (c = 0; c < children; c++) {
                                nvlist_t *holey;

                                if (child[c] != NULL ||
                                    !vdev_is_hole(hole_array, holes, c))
                                        continue;

                                if (nvlist_alloc(&holey, NV_UNIQUE_NAME,
                                    0) != 0)
                                        goto nomem;

                                /*
                                 * Holes in the namespace are treated as
                                 * "hole" top-level vdevs and have a
                                 * special flag set on them.
                                 */
                                if (nvlist_add_string(holey,
                                    ZPOOL_CONFIG_TYPE,
                                    VDEV_TYPE_HOLE) != 0 ||
                                    nvlist_add_uint64(holey,
                                    ZPOOL_CONFIG_ID, c) != 0 ||
                                    nvlist_add_uint64(holey,
                                    ZPOOL_CONFIG_GUID, 0ULL) != 0) {
                                        nvlist_free(holey);
                                        goto nomem;
                                }
                                child[c] = holey;
                        }
                }

                /*
                 * Look for any missing top-level vdevs.  If this is the case,
                 * create a faked up 'missing' vdev as a placeholder.  We cannot
                 * simply compress the child array, because the kernel performs
                 * certain checks to make sure the vdev IDs match their location
                 * in the configuration.
                 */
                for (c = 0; c < children; c++) {
                        if (child[c] == NULL) {
                                nvlist_t *missing;
                                if (nvlist_alloc(&missing, NV_UNIQUE_NAME,
                                    0) != 0)
                                        goto nomem;
                                if (nvlist_add_string(missing,
                                    ZPOOL_CONFIG_TYPE,
                                    VDEV_TYPE_MISSING) != 0 ||
                                    nvlist_add_uint64(missing,
                                    ZPOOL_CONFIG_ID, c) != 0 ||
                                    nvlist_add_uint64(missing,
                                    ZPOOL_CONFIG_GUID, 0ULL) != 0) {
                                        nvlist_free(missing);
                                        goto nomem;
                                }
                                child[c] = missing;
                        }
                }

                /*
                 * Put all of this pool's top-level vdevs into a root vdev.
                 */
                if (nvlist_alloc(&nvroot, NV_UNIQUE_NAME, 0) != 0)
                        goto nomem;
                if (nvlist_add_string(nvroot, ZPOOL_CONFIG_TYPE,
                    VDEV_TYPE_ROOT) != 0 ||
                    nvlist_add_uint64(nvroot, ZPOOL_CONFIG_ID, 0ULL) != 0 ||
                    nvlist_add_uint64(nvroot, ZPOOL_CONFIG_GUID, guid) != 0 ||
                    nvlist_add_nvlist_array(nvroot, ZPOOL_CONFIG_CHILDREN,
                    child, children) != 0) {
                        nvlist_free(nvroot);
                        goto nomem;
                }

                for (c = 0; c < children; c++)
                        nvlist_free(child[c]);
                free(child);
                children = 0;
                child = NULL;

                /*
                 * Go through and fix up any paths and/or devids based on our
                 * known list of vdev GUID -> path mappings.
                 */
                if (fix_paths(nvroot, pl->names) != 0) {
                        nvlist_free(nvroot);
                        goto nomem;
                }

                /*
                 * Add the root vdev to this pool's configuration.
                 */
                if (nvlist_add_nvlist(config, ZPOOL_CONFIG_VDEV_TREE,
                    nvroot) != 0) {
                        nvlist_free(nvroot);
                        goto nomem;
                }
                nvlist_free(nvroot);

                /*
                 * zdb uses this path to report on active pools that were
                 * imported or created using -R.
                 */
                if (active_ok)
                        goto add_pool;

                /*
                 * Determine if this pool is currently active, in which case we
                 * can't actually import it.
                 */
                verify(nvlist_lookup_string(config, ZPOOL_CONFIG_POOL_NAME,
                    &name) == 0);
                verify(nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_GUID,
                    &guid) == 0);

                if (pool_active(hdl, name, guid, &isactive) != 0)
                        goto error;

                if (isactive) {
                        nvlist_free(config);
                        config = NULL;
                        continue;
                }

                if ((nvl = refresh_config(hdl, config)) == NULL) {
                        nvlist_free(config);
                        config = NULL;
                        continue;
                }

                nvlist_free(config);
                config = nvl;

                /*
                 * Go through and update the paths for spares, now that we have
                 * them.
                 */
                verify(nvlist_lookup_nvlist(config, ZPOOL_CONFIG_VDEV_TREE,
                    &nvroot) == 0);
                if (nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_SPARES,
                    &spares, &nspares) == 0) {
                        for (i = 0; i < nspares; i++) {
                                if (fix_paths(spares[i], pl->names) != 0)
                                        goto nomem;
                        }
                }

                /*
                 * Update the paths for l2cache devices.
                 */
                if (nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_L2CACHE,
                    &l2cache, &nl2cache) == 0) {
                        for (i = 0; i < nl2cache; i++) {
                                if (fix_paths(l2cache[i], pl->names) != 0)
                                        goto nomem;
                        }
                }

                /*
                 * Restore the original information read from the actual label.
                 */
                (void) nvlist_remove(config, ZPOOL_CONFIG_HOSTID,
                    DATA_TYPE_UINT64);
                (void) nvlist_remove(config, ZPOOL_CONFIG_HOSTNAME,
                    DATA_TYPE_STRING);
                if (hostid != 0) {
                        verify(nvlist_add_uint64(config, ZPOOL_CONFIG_HOSTID,
                            hostid) == 0);
                        verify(nvlist_add_string(config, ZPOOL_CONFIG_HOSTNAME,
                            hostname) == 0);
                }

add_pool:
                /*
                 * Add this pool to the list of configs.
                 */
                verify(nvlist_lookup_string(config, ZPOOL_CONFIG_POOL_NAME,
                    &name) == 0);
                if (nvlist_add_nvlist(ret, name, config) != 0)
                        goto nomem;

                found_one = B_TRUE;
                nvlist_free(config);
                config = NULL;
        }

        if (!found_one) {
                nvlist_free(ret);
                ret = NULL;
        }

        return (ret);

nomem:
        (void) no_memory(hdl);
error:
        nvlist_free(config);
        nvlist_free(ret);
        for (c = 0; c < children; c++)
                nvlist_free(child[c]);
        free(child);

        return (NULL);
}

/*
 * Return the offset of the given label.
 */
static uint64_t
label_offset(uint64_t size, int l)
{
        ASSERT(P2PHASE_TYPED(size, sizeof (vdev_label_t), uint64_t) == 0);
        return (l * sizeof (vdev_label_t) + (l < VDEV_LABELS / 2 ?
            0 : size - VDEV_LABELS * sizeof (vdev_label_t)));
}

/*
 * Given a file descriptor, read the label information and return an nvlist
 * describing the configuration, if there is one.
 */
int
zpool_read_label(int fd, nvlist_t **config)
{
        struct stat64 statbuf;
        int l;
        vdev_label_t *label;
        uint64_t state, txg, size;

        *config = NULL;

        if (fstat64(fd, &statbuf) == -1)
                return (0);
        size = P2ALIGN_TYPED(statbuf.st_size, sizeof (vdev_label_t), uint64_t);

        if ((label = malloc(sizeof (vdev_label_t))) == NULL)
                return (-1);

        for (l = 0; l < VDEV_LABELS; l++) {
                if (pread64(fd, label, sizeof (vdev_label_t),
                    label_offset(size, l)) != sizeof (vdev_label_t))
                        continue;

                if (nvlist_unpack(label->vl_vdev_phys.vp_nvlist,
                    sizeof (label->vl_vdev_phys.vp_nvlist), config, 0) != 0)
                        continue;

                if (nvlist_lookup_uint64(*config, ZPOOL_CONFIG_POOL_STATE,
                    &state) != 0 || state > POOL_STATE_L2CACHE) {
                        nvlist_free(*config);
                        continue;
                }

                if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
                    (nvlist_lookup_uint64(*config, ZPOOL_CONFIG_POOL_TXG,
                    &txg) != 0 || txg == 0)) {
                        nvlist_free(*config);
                        continue;
                }

                free(label);
                return (0);
        }

        free(label);
        *config = NULL;
        return (0);
}

typedef struct rdsk_node {
        char *rn_name;
        int rn_dfd;
        libzfs_handle_t *rn_hdl;
        nvlist_t *rn_config;
        avl_tree_t *rn_avl;
        avl_node_t rn_node;
        boolean_t rn_nozpool;
} rdsk_node_t;

static int
slice_cache_compare(const void *arg1, const void *arg2)
{
        const char  *nm1 = ((rdsk_node_t *)arg1)->rn_name;
        const char  *nm2 = ((rdsk_node_t *)arg2)->rn_name;
        char *nm1slice, *nm2slice;
        int rv;

        /*
         * slices zero and two are the most likely to provide results,
         * so put those first
         */
        nm1slice = strstr(nm1, "s0");
        nm2slice = strstr(nm2, "s0");
        if (nm1slice && !nm2slice) {
                return (-1);
        }
        if (!nm1slice && nm2slice) {
                return (1);
        }
        nm1slice = strstr(nm1, "s2");
        nm2slice = strstr(nm2, "s2");
        if (nm1slice && !nm2slice) {
                return (-1);
        }
        if (!nm1slice && nm2slice) {
                return (1);
        }

        rv = strcmp(nm1, nm2);
        if (rv == 0)
                return (0);
        return (rv > 0 ? 1 : -1);
}

static void
check_one_slice(avl_tree_t *r, char *diskname, uint_t partno,
    diskaddr_t size, uint_t blksz)
{
        rdsk_node_t tmpnode;
        rdsk_node_t *node;
        char sname[MAXNAMELEN];

        tmpnode.rn_name = &sname[0];
        (void) snprintf(tmpnode.rn_name, MAXNAMELEN, "%s%u",
            diskname, partno);
        /*
         * protect against division by zero for disk labels that
         * contain a bogus sector size
         */
        if (blksz == 0)
                blksz = DEV_BSIZE;
        /* too small to contain a zpool? */
        if ((size < (SPA_MINDEVSIZE / blksz)) &&
            (node = avl_find(r, &tmpnode, NULL)))
                node->rn_nozpool = B_TRUE;
}

static void
nozpool_all_slices(avl_tree_t *r, const char *sname)
{
        char diskname[MAXNAMELEN];
        char *ptr;
        int i;

        (void) strncpy(diskname, sname, MAXNAMELEN);
        if (((ptr = strrchr(diskname, 's')) == NULL) &&
            ((ptr = strrchr(diskname, 'p')) == NULL))
                return;
        ptr[0] = 's';
        ptr[1] = '\0';
        for (i = 0; i < NDKMAP; i++)
                check_one_slice(r, diskname, i, 0, 1);
        ptr[0] = 'p';
        for (i = 0; i <= FD_NUMPART; i++)
                check_one_slice(r, diskname, i, 0, 1);
}

static void
check_slices(avl_tree_t *r, int fd, const char *sname)
{
        struct extvtoc vtoc;
        struct dk_gpt *gpt;
        char diskname[MAXNAMELEN];
        char *ptr;
        int i;

        (void) strncpy(diskname, sname, MAXNAMELEN);
        if ((ptr = strrchr(diskname, 's')) == NULL || !isdigit(ptr[1]))
                return;
        ptr[1] = '\0';

        if (read_extvtoc(fd, &vtoc) >= 0) {
                for (i = 0; i < NDKMAP; i++)
                        check_one_slice(r, diskname, i,
                            vtoc.v_part[i].p_size, vtoc.v_sectorsz);
        } else if (efi_alloc_and_read(fd, &gpt) >= 0) {
                /*
                 * on x86 we'll still have leftover links that point
                 * to slices s[9-15], so use NDKMAP instead
                 */
                for (i = 0; i < NDKMAP; i++)
                        check_one_slice(r, diskname, i,
                            gpt->efi_parts[i].p_size, gpt->efi_lbasize);
                /* nodes p[1-4] are never used with EFI labels */
                ptr[0] = 'p';
                for (i = 1; i <= FD_NUMPART; i++)
                        check_one_slice(r, diskname, i, 0, 1);
                efi_free(gpt);
        }
}

static void
zpool_open_func(void *arg)
{
        rdsk_node_t *rn = arg;
        struct stat64 statbuf;
        nvlist_t *config;
        int fd;

        if (rn->rn_nozpool)
                return;
        if ((fd = openat64(rn->rn_dfd, rn->rn_name, O_RDONLY)) < 0) {
                /* symlink to a device that's no longer there */
                if (errno == ENOENT)
                        nozpool_all_slices(rn->rn_avl, rn->rn_name);
                return;
        }
        /*
         * Ignore failed stats.  We only want regular
         * files, character devs and block devs.
         */
        if (fstat64(fd, &statbuf) != 0 ||
            (!S_ISREG(statbuf.st_mode) &&
            !S_ISCHR(statbuf.st_mode) &&
            !S_ISBLK(statbuf.st_mode))) {
                (void) close(fd);
                return;
        }
        /* this file is too small to hold a zpool */
        if (S_ISREG(statbuf.st_mode) &&
            statbuf.st_size < SPA_MINDEVSIZE) {
                (void) close(fd);
                return;
        } else if (!S_ISREG(statbuf.st_mode)) {
                /*
                 * Try to read the disk label first so we don't have to
                 * open a bunch of minor nodes that can't have a zpool.
                 */
                check_slices(rn->rn_avl, fd, rn->rn_name);
        }

        if ((zpool_read_label(fd, &config)) != 0) {
                (void) close(fd);
                (void) no_memory(rn->rn_hdl);
                return;
        }
        (void) close(fd);


        rn->rn_config = config;
        if (config != NULL) {
                assert(rn->rn_nozpool == B_FALSE);
        }
}

/*
 * Given a file descriptor, clear (zero) the label information.  This function
 * is currently only used in the appliance stack as part of the ZFS sysevent
 * module.
 */
int
zpool_clear_label(int fd)
{
        struct stat64 statbuf;
        int l;
        vdev_label_t *label;
        uint64_t size;

        if (fstat64(fd, &statbuf) == -1)
                return (0);
        size = P2ALIGN_TYPED(statbuf.st_size, sizeof (vdev_label_t), uint64_t);

        if ((label = calloc(sizeof (vdev_label_t), 1)) == NULL)
                return (-1);

        for (l = 0; l < VDEV_LABELS; l++) {
                if (pwrite64(fd, label, sizeof (vdev_label_t),
                    label_offset(size, l)) != sizeof (vdev_label_t)) {
                        free(label);
                        return (-1);
                }
        }

        free(label);
        return (0);
}

/*
 * Given a list of directories to search, find all pools stored on disk.  This
 * includes partial pools which are not available to import.  If no args are
 * given (argc is 0), then the default directory (/dev/dsk) is searched.
 * poolname or guid (but not both) are provided by the caller when trying
 * to import a specific pool.
 */
static nvlist_t *
zpool_find_import_impl(libzfs_handle_t *hdl, importargs_t *iarg)
{
        int i, dirs = iarg->paths;
        struct dirent64 *dp;
        char path[MAXPATHLEN];
        char *end, **dir = iarg->path;
        size_t pathleft;
        nvlist_t *ret = NULL;
        static char *default_dir = "/dev/dsk";
        pool_list_t pools = { 0 };
        pool_entry_t *pe, *penext;
        vdev_entry_t *ve, *venext;
        config_entry_t *ce, *cenext;
        name_entry_t *ne, *nenext;
        avl_tree_t slice_cache;
        rdsk_node_t *slice;
        void *cookie;

        if (dirs == 0) {
                dirs = 1;
                dir = &default_dir;
        }

        /*
         * Go through and read the label configuration information from every
         * possible device, organizing the information according to pool GUID
         * and toplevel GUID.
         */
        for (i = 0; i < dirs; i++) {
                tpool_t *t;
                char *rdsk;
                int dfd;
                boolean_t config_failed = B_FALSE;
                DIR *dirp;

                /* use realpath to normalize the path */
                if (realpath(dir[i], path) == 0) {
                        (void) zfs_error_fmt(hdl, EZFS_BADPATH,
                            dgettext(TEXT_DOMAIN, "cannot open '%s'"), dir[i]);
                        goto error;
                }
                end = &path[strlen(path)];
                *end++ = '/';
                *end = 0;
                pathleft = &path[sizeof (path)] - end;

                /*
                 * Using raw devices instead of block devices when we're
                 * reading the labels skips a bunch of slow operations during
                 * close(2) processing, so we replace /dev/dsk with /dev/rdsk.
                 */
                if (strcmp(path, "/dev/dsk/") == 0)
                        rdsk = "/dev/rdsk/";
                else
                        rdsk = path;

                if ((dfd = open64(rdsk, O_RDONLY)) < 0 ||
                    (dirp = fdopendir(dfd)) == NULL) {
                        if (dfd >= 0)
                                (void) close(dfd);
                        zfs_error_aux(hdl, strerror(errno));
                        (void) zfs_error_fmt(hdl, EZFS_BADPATH,
                            dgettext(TEXT_DOMAIN, "cannot open '%s'"),
                            rdsk);
                        goto error;
                }

                avl_create(&slice_cache, slice_cache_compare,
                    sizeof (rdsk_node_t), offsetof(rdsk_node_t, rn_node));
                /*
                 * This is not MT-safe, but we have no MT consumers of libzfs
                 */
                while ((dp = readdir64(dirp)) != NULL) {
                        const char *name = dp->d_name;
                        if (name[0] == '.' &&
                            (name[1] == 0 || (name[1] == '.' && name[2] == 0)))
                                continue;

                        slice = zfs_alloc(hdl, sizeof (rdsk_node_t));
                        slice->rn_name = zfs_strdup(hdl, name);
                        slice->rn_avl = &slice_cache;
                        slice->rn_dfd = dfd;
                        slice->rn_hdl = hdl;
                        slice->rn_nozpool = B_FALSE;
                        avl_add(&slice_cache, slice);
                }
                /*
                 * create a thread pool to do all of this in parallel;
                 * rn_nozpool is not protected, so this is racy in that
                 * multiple tasks could decide that the same slice can
                 * not hold a zpool, which is benign.  Also choose
                 * double the number of processors; we hold a lot of
                 * locks in the kernel, so going beyond this doesn't
                 * buy us much.
                 */
                t = tpool_create(1, 2 * sysconf(_SC_NPROCESSORS_ONLN),
                    0, NULL);
                for (slice = avl_first(&slice_cache); slice;
                    (slice = avl_walk(&slice_cache, slice,
                    AVL_AFTER)))
                        (void) tpool_dispatch(t, zpool_open_func, slice);
                tpool_wait(t);
                tpool_destroy(t);

                cookie = NULL;
                while ((slice = avl_destroy_nodes(&slice_cache,
                    &cookie)) != NULL) {
                        if (slice->rn_config != NULL && !config_failed) {
                                nvlist_t *config = slice->rn_config;
                                boolean_t matched = B_TRUE;

                                if (iarg->poolname != NULL) {
                                        char *pname;

                                        matched = nvlist_lookup_string(config,
                                            ZPOOL_CONFIG_POOL_NAME,
                                            &pname) == 0 &&
                                            strcmp(iarg->poolname, pname) == 0;
                                } else if (iarg->guid != 0) {
                                        uint64_t this_guid;

                                        matched = nvlist_lookup_uint64(config,
                                            ZPOOL_CONFIG_POOL_GUID,
                                            &this_guid) == 0 &&
                                            iarg->guid == this_guid;
                                }
                                if (!matched) {
                                        nvlist_free(config);
                                } else {
                                        /*
                                         * use the non-raw path for the config
                                         */
                                        (void) strlcpy(end, slice->rn_name,
                                            pathleft);
                                        if (add_config(hdl, &pools, path,
                                            config) != 0)
                                                config_failed = B_TRUE;
                                }
                        }
                        free(slice->rn_name);
                        free(slice);
                }
                avl_destroy(&slice_cache);

                (void) closedir(dirp);

                if (config_failed)
                        goto error;
        }

        ret = get_configs(hdl, &pools, iarg->can_be_active);

error:
        for (pe = pools.pools; pe != NULL; pe = penext) {
                penext = pe->pe_next;
                for (ve = pe->pe_vdevs; ve != NULL; ve = venext) {
                        venext = ve->ve_next;
                        for (ce = ve->ve_configs; ce != NULL; ce = cenext) {
                                cenext = ce->ce_next;
                                if (ce->ce_config)
                                        nvlist_free(ce->ce_config);
                                free(ce);
                        }
                        free(ve);
                }
                free(pe);
        }

        for (ne = pools.names; ne != NULL; ne = nenext) {
                nenext = ne->ne_next;
                free(ne->ne_name);
                free(ne);
        }

        return (ret);
}

nvlist_t *
zpool_find_import(libzfs_handle_t *hdl, int argc, char **argv)
{
        importargs_t iarg = { 0 };

        iarg.paths = argc;
        iarg.path = argv;

        return (zpool_find_import_impl(hdl, &iarg));
}

/*
 * Given a cache file, return the contents as a list of importable pools.
 * poolname or guid (but not both) are provided by the caller when trying
 * to import a specific pool.
 */
nvlist_t *
zpool_find_import_cached(libzfs_handle_t *hdl, const char *cachefile,
    char *poolname, uint64_t guid)
{
        char *buf;
        int fd;
        struct stat64 statbuf;
        nvlist_t *raw, *src, *dst;
        nvlist_t *pools;
        nvpair_t *elem;
        char *name;
        uint64_t this_guid;
        boolean_t active;

        verify(poolname == NULL || guid == 0);

        if ((fd = open(cachefile, O_RDONLY)) < 0) {
                zfs_error_aux(hdl, "%s", strerror(errno));
                (void) zfs_error(hdl, EZFS_BADCACHE,
                    dgettext(TEXT_DOMAIN, "failed to open cache file"));
                return (NULL);
        }

        if (fstat64(fd, &statbuf) != 0) {
                zfs_error_aux(hdl, "%s", strerror(errno));
                (void) close(fd);
                (void) zfs_error(hdl, EZFS_BADCACHE,
                    dgettext(TEXT_DOMAIN, "failed to get size of cache file"));
                return (NULL);
        }

        if ((buf = zfs_alloc(hdl, statbuf.st_size)) == NULL) {
                (void) close(fd);
                return (NULL);
        }

        if (read(fd, buf, statbuf.st_size) != statbuf.st_size) {
                (void) close(fd);
                free(buf);
                (void) zfs_error(hdl, EZFS_BADCACHE,
                    dgettext(TEXT_DOMAIN,
                    "failed to read cache file contents"));
                return (NULL);
        }

        (void) close(fd);

        if (nvlist_unpack(buf, statbuf.st_size, &raw, 0) != 0) {
                free(buf);
                (void) zfs_error(hdl, EZFS_BADCACHE,
                    dgettext(TEXT_DOMAIN,
                    "invalid or corrupt cache file contents"));
                return (NULL);
        }

        free(buf);

        /*
         * Go through and get the current state of the pools and refresh their
         * state.
         */
        if (nvlist_alloc(&pools, 0, 0) != 0) {
                (void) no_memory(hdl);
                nvlist_free(raw);
                return (NULL);
        }

        elem = NULL;
        while ((elem = nvlist_next_nvpair(raw, elem)) != NULL) {
                src = fnvpair_value_nvlist(elem);

                name = fnvlist_lookup_string(src, ZPOOL_CONFIG_POOL_NAME);
                if (poolname != NULL && strcmp(poolname, name) != 0)
                        continue;

                this_guid = fnvlist_lookup_uint64(src, ZPOOL_CONFIG_POOL_GUID);
                if (guid != 0 && guid != this_guid)
                        continue;

                if (pool_active(hdl, name, this_guid, &active) != 0) {
                        nvlist_free(raw);
                        nvlist_free(pools);
                        return (NULL);
                }

                if (active)
                        continue;

                if ((dst = refresh_config(hdl, src)) == NULL) {
                        nvlist_free(raw);
                        nvlist_free(pools);
                        return (NULL);
                }

                if (nvlist_add_nvlist(pools, nvpair_name(elem), dst) != 0) {
                        (void) no_memory(hdl);
                        nvlist_free(dst);
                        nvlist_free(raw);
                        nvlist_free(pools);
                        return (NULL);
                }
                nvlist_free(dst);
        }

        nvlist_free(raw);
        return (pools);
}

static int
name_or_guid_exists(zpool_handle_t *zhp, void *data)
{
        importargs_t *import = data;
        int found = 0;

        if (import->poolname != NULL) {
                char *pool_name;

                verify(nvlist_lookup_string(zhp->zpool_config,
                    ZPOOL_CONFIG_POOL_NAME, &pool_name) == 0);
                if (strcmp(pool_name, import->poolname) == 0)
                        found = 1;
        } else {
                uint64_t pool_guid;

                verify(nvlist_lookup_uint64(zhp->zpool_config,
                    ZPOOL_CONFIG_POOL_GUID, &pool_guid) == 0);
                if (pool_guid == import->guid)
                        found = 1;
        }

        zpool_close(zhp);
        return (found);
}

nvlist_t *
zpool_search_import(libzfs_handle_t *hdl, importargs_t *import)
{
        verify(import->poolname == NULL || import->guid == 0);

        if (import->unique)
                import->exists = zpool_iter(hdl, name_or_guid_exists, import);

        if (import->cachefile != NULL)
                return (zpool_find_import_cached(hdl, import->cachefile,
                    import->poolname, import->guid));

        return (zpool_find_import_impl(hdl, import));
}

boolean_t
find_guid(nvlist_t *nv, uint64_t guid)
{
        uint64_t tmp;
        nvlist_t **child;
        uint_t c, children;

        verify(nvlist_lookup_uint64(nv, ZPOOL_CONFIG_GUID, &tmp) == 0);
        if (tmp == guid)
                return (B_TRUE);

        if (nvlist_lookup_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN,
            &child, &children) == 0) {
                for (c = 0; c < children; c++)
                        if (find_guid(child[c], guid))
                                return (B_TRUE);
        }

        return (B_FALSE);
}

typedef struct aux_cbdata {
        const char      *cb_type;
        uint64_t        cb_guid;
        zpool_handle_t  *cb_zhp;
} aux_cbdata_t;

static int
find_aux(zpool_handle_t *zhp, void *data)
{
        aux_cbdata_t *cbp = data;
        nvlist_t **list;
        uint_t i, count;
        uint64_t guid;
        nvlist_t *nvroot;

        verify(nvlist_lookup_nvlist(zhp->zpool_config, ZPOOL_CONFIG_VDEV_TREE,
            &nvroot) == 0);

        if (nvlist_lookup_nvlist_array(nvroot, cbp->cb_type,
            &list, &count) == 0) {
                for (i = 0; i < count; i++) {
                        verify(nvlist_lookup_uint64(list[i],
                            ZPOOL_CONFIG_GUID, &guid) == 0);
                        if (guid == cbp->cb_guid) {
                                cbp->cb_zhp = zhp;
                                return (1);
                        }
                }
        }

        zpool_close(zhp);
        return (0);
}

/*
 * Determines if the pool is in use.  If so, it returns true and the state of
 * the pool as well as the name of the pool.  Both strings are allocated and
 * must be freed by the caller.
 */
int
zpool_in_use(libzfs_handle_t *hdl, int fd, pool_state_t *state, char **namestr,
    boolean_t *inuse)
{
        nvlist_t *config;
        char *name;
        boolean_t ret;
        uint64_t guid, vdev_guid;
        zpool_handle_t *zhp;
        nvlist_t *pool_config;
        uint64_t stateval, isspare;
        aux_cbdata_t cb = { 0 };
        boolean_t isactive;

        *inuse = B_FALSE;

        if (zpool_read_label(fd, &config) != 0) {
                (void) no_memory(hdl);
                return (-1);
        }

        if (config == NULL)
                return (0);

        verify(nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_STATE,
            &stateval) == 0);
        verify(nvlist_lookup_uint64(config, ZPOOL_CONFIG_GUID,
            &vdev_guid) == 0);

        if (stateval != POOL_STATE_SPARE && stateval != POOL_STATE_L2CACHE) {
                verify(nvlist_lookup_string(config, ZPOOL_CONFIG_POOL_NAME,
                    &name) == 0);
                verify(nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_GUID,
                    &guid) == 0);
        }

        switch (stateval) {
        case POOL_STATE_EXPORTED:
                /*
                 * A pool with an exported state may in fact be imported
                 * read-only, so check the in-core state to see if it's
                 * active and imported read-only.  If it is, set
                 * its state to active.
                 */
                if (pool_active(hdl, name, guid, &isactive) == 0 && isactive &&
                    (zhp = zpool_open_canfail(hdl, name)) != NULL) {
                        if (zpool_get_prop_int(zhp, ZPOOL_PROP_READONLY, NULL))
                                stateval = POOL_STATE_ACTIVE;

                        /*
                         * All we needed the zpool handle for is the
                         * readonly prop check.
                         */
                        zpool_close(zhp);
                }

                ret = B_TRUE;
                break;

        case POOL_STATE_ACTIVE:
                /*
                 * For an active pool, we have to determine if it's really part
                 * of a currently active pool (in which case the pool will exist
                 * and the guid will be the same), or whether it's part of an
                 * active pool that was disconnected without being explicitly
                 * exported.
                 */
                if (pool_active(hdl, name, guid, &isactive) != 0) {
                        nvlist_free(config);
                        return (-1);
                }

                if (isactive) {
                        /*
                         * Because the device may have been removed while
                         * offlined, we only report it as active if the vdev is
                         * still present in the config.  Otherwise, pretend like
                         * it's not in use.
                         */
                        if ((zhp = zpool_open_canfail(hdl, name)) != NULL &&
                            (pool_config = zpool_get_config(zhp, NULL))
                            != NULL) {
                                nvlist_t *nvroot;

                                verify(nvlist_lookup_nvlist(pool_config,
                                    ZPOOL_CONFIG_VDEV_TREE, &nvroot) == 0);
                                ret = find_guid(nvroot, vdev_guid);
                        } else {
                                ret = B_FALSE;
                        }

                        /*
                         * If this is an active spare within another pool, we
                         * treat it like an unused hot spare.  This allows the
                         * user to create a pool with a hot spare that currently
                         * in use within another pool.  Since we return B_TRUE,
                         * libdiskmgt will continue to prevent generic consumers
                         * from using the device.
                         */
                        if (ret && nvlist_lookup_uint64(config,
                            ZPOOL_CONFIG_IS_SPARE, &isspare) == 0 && isspare)
                                stateval = POOL_STATE_SPARE;

                        if (zhp != NULL)
                                zpool_close(zhp);
                } else {
                        stateval = POOL_STATE_POTENTIALLY_ACTIVE;
                        ret = B_TRUE;
                }
                break;

        case POOL_STATE_SPARE:
                /*
                 * For a hot spare, it can be either definitively in use, or
                 * potentially active.  To determine if it's in use, we iterate
                 * over all pools in the system and search for one with a spare
                 * with a matching guid.
                 *
                 * Due to the shared nature of spares, we don't actually report
                 * the potentially active case as in use.  This means the user
                 * can freely create pools on the hot spares of exported pools,
                 * but to do otherwise makes the resulting code complicated, and
                 * we end up having to deal with this case anyway.
                 */
                cb.cb_zhp = NULL;
                cb.cb_guid = vdev_guid;
                cb.cb_type = ZPOOL_CONFIG_SPARES;
                if (zpool_iter(hdl, find_aux, &cb) == 1) {
                        name = (char *)zpool_get_name(cb.cb_zhp);
                        ret = B_TRUE;
                } else {
                        ret = B_FALSE;
                }
                break;

        case POOL_STATE_L2CACHE:

                /*
                 * Check if any pool is currently using this l2cache device.
                 */
                cb.cb_zhp = NULL;
                cb.cb_guid = vdev_guid;
                cb.cb_type = ZPOOL_CONFIG_L2CACHE;
                if (zpool_iter(hdl, find_aux, &cb) == 1) {
                        name = (char *)zpool_get_name(cb.cb_zhp);
                        ret = B_TRUE;
                } else {
                        ret = B_FALSE;
                }
                break;

        default:
                ret = B_FALSE;
        }


        if (ret) {
                if ((*namestr = zfs_strdup(hdl, name)) == NULL) {
                        if (cb.cb_zhp)
                                zpool_close(cb.cb_zhp);
                        nvlist_free(config);
                        return (-1);
                }
                *state = (pool_state_t)stateval;
        }

        if (cb.cb_zhp)
                zpool_close(cb.cb_zhp);

        nvlist_free(config);
        *inuse = ret;
        return (0);
}