Fix intermittent 'zpool add' failures

[mirror_zfs-debian.git] / cmd / zpool / zpool_vdev.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 (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 */

/*
 * Functions to convert between a list of vdevs and an nvlist representing the
 * configuration.  Each entry in the list can be one of:
 *
 *      Device vdevs
 *              disk=(path=..., devid=...)
 *              file=(path=...)
 *
 *      Group vdevs
 *              raidz[1|2]=(...)
 *              mirror=(...)
 *
 *      Hot spares
 *
 * While the underlying implementation supports it, group vdevs cannot contain
 * other group vdevs.  All userland verification of devices is contained within
 * this file.  If successful, the nvlist returned can be passed directly to the
 * kernel; we've done as much verification as possible in userland.
 *
 * Hot spares are a special case, and passed down as an array of disk vdevs, at
 * the same level as the root of the vdev tree.
 *
 * The only function exported by this file is 'make_root_vdev'.  The
 * function performs several passes:
 *
 *      1. Construct the vdev specification.  Performs syntax validation and
 *         makes sure each device is valid.
 *      2. Check for devices in use.  Using libblkid to make sure that no
 *         devices are also in use.  Some can be overridden using the 'force'
 *         flag, others cannot.
 *      3. Check for replication errors if the 'force' flag is not specified.
 *         validates that the replication level is consistent across the
 *         entire pool.
 *      4. Call libzfs to label any whole disks with an EFI label.
 */

#include <assert.h>
#include <ctype.h>
#include <devid.h>
#include <errno.h>
#include <fcntl.h>
#include <libintl.h>
#include <libnvpair.h>
#include <limits.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/efi_partition.h>
#include <sys/stat.h>
#include <sys/vtoc.h>
#include <sys/mntent.h>
#include <uuid/uuid.h>
#ifdef HAVE_LIBBLKID
#include <blkid/blkid.h>
#else
#define blkid_cache void *
#endif /* HAVE_LIBBLKID */

#include "zpool_util.h"

/*
 * For any given vdev specification, we can have multiple errors.  The
 * vdev_error() function keeps track of whether we have seen an error yet, and
 * prints out a header if its the first error we've seen.
 */
boolean_t error_seen;
boolean_t is_force;

/*PRINTFLIKE1*/
static void
vdev_error(const char *fmt, ...)
{
        va_list ap;

        if (!error_seen) {
                (void) fprintf(stderr, gettext("invalid vdev specification\n"));
                if (!is_force)
                        (void) fprintf(stderr, gettext("use '-f' to override "
                            "the following errors:\n"));
                else
                        (void) fprintf(stderr, gettext("the following errors "
                            "must be manually repaired:\n"));
                error_seen = B_TRUE;
        }

        va_start(ap, fmt);
        (void) vfprintf(stderr, fmt, ap);
        va_end(ap);
}

/*
 * Check that a file is valid.  All we can do in this case is check that it's
 * not in use by another pool, and not in use by swap.
 */
static int
check_file(const char *file, boolean_t force, boolean_t isspare)
{
        char  *name;
        int fd;
        int ret = 0;
        pool_state_t state;
        boolean_t inuse;

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

        if (zpool_in_use(g_zfs, fd, &state, &name, &inuse) == 0 && inuse) {
                const char *desc;

                switch (state) {
                case POOL_STATE_ACTIVE:
                        desc = gettext("active");
                        break;

                case POOL_STATE_EXPORTED:
                        desc = gettext("exported");
                        break;

                case POOL_STATE_POTENTIALLY_ACTIVE:
                        desc = gettext("potentially active");
                        break;

                default:
                        desc = gettext("unknown");
                        break;
                }

                /*
                 * Allow hot spares to be shared between pools.
                 */
                if (state == POOL_STATE_SPARE && isspare)
                        return (0);

                if (state == POOL_STATE_ACTIVE ||
                    state == POOL_STATE_SPARE || !force) {
                        switch (state) {
                        case POOL_STATE_SPARE:
                                vdev_error(gettext("%s is reserved as a hot "
                                    "spare for pool %s\n"), file, name);
                                break;
                        default:
                                vdev_error(gettext("%s is part of %s pool "
                                    "'%s'\n"), file, desc, name);
                                break;
                        }
                        ret = -1;
                }

                free(name);
        }

        (void) close(fd);
        return (ret);
}

static void
check_error(int err)
{
        (void) fprintf(stderr, gettext("warning: device in use checking "
            "failed: %s\n"), strerror(err));
}

static int
check_slice(const char *path, blkid_cache cache, int force, boolean_t isspare)
{
        struct stat64 statbuf;
        int err;
#ifdef HAVE_LIBBLKID
        char *value;
#endif /* HAVE_LIBBLKID */

        if (stat64(path, &statbuf) != 0) {
                vdev_error(gettext("cannot stat %s: %s\n"),
                           path, strerror(errno));
                return (-1);
        }

#ifdef HAVE_LIBBLKID
        /* No valid type detected device is safe to use */
        value = blkid_get_tag_value(cache, "TYPE", path);
        if (value == NULL)
                return (0);

        /*
         * If libblkid detects a ZFS device, we check the device
         * using check_file() to see if it's safe.  The one safe
         * case is a spare device shared between multiple pools.
         */
        if (strcmp(value, "zfs") == 0) {
                err = check_file(path, force, isspare);
        } else {
                if (force) {
                        err = 0;
                } else {
                        err = -1;
                        vdev_error(gettext("%s contains a filesystem of "
                                   "type '%s'\n"), path, value);
                }
        }

        free(value);
#else
        err = check_file(path, force, isspare);
#endif /* HAVE_LIBBLKID */

        return (err);
}

/*
 * Validate a whole disk.  Iterate over all slices on the disk and make sure
 * that none is in use by calling check_slice().
 */
static int
check_disk(const char *path, blkid_cache cache, int force,
           boolean_t isspare, boolean_t iswholedisk)
{
        struct dk_gpt *vtoc;
        char slice_path[MAXPATHLEN];
        int err = 0;
        int fd, i;

        /* This is not a wholedisk we only check the given partition */
        if (!iswholedisk)
                return check_slice(path, cache, force, isspare);

        /*
         * When the device is a whole disk try to read the efi partition
         * label.  If this is successful we safely check the all of the
         * partitions.  However, when it fails it may simply be because
         * the disk is partitioned via the MBR.  Since we currently can
         * not easily decode the MBR return a failure and prompt to the
         * user to use force option since we cannot check the partitions.
         */
        if ((fd = open(path, O_RDWR|O_DIRECT|O_EXCL)) < 0) {
                check_error(errno);
                return -1;
        }

        if ((err = efi_alloc_and_read(fd, &vtoc)) != 0) {
                (void) close(fd);

                if (force) {
                        return 0;
                } else {
                        vdev_error(gettext("%s does not contain an EFI "
                            "label but it may contain partition\n"
                            "information in the MBR.\n"), path);
                        return -1;
                }
        }

        /*
         * The primary efi partition label is damaged however the secondary
         * label at the end of the device is intact.  Rather than use this
         * label we should play it safe and treat this as a non efi device.
         */
        if (vtoc->efi_flags & EFI_GPT_PRIMARY_CORRUPT) {
                efi_free(vtoc);
                (void) close(fd);

                if (force) {
                        /* Partitions will no be created using the backup */
                        return 0;
                } else {
                        vdev_error(gettext("%s contains a corrupt primary "
                            "EFI label.\n"), path);
                        return -1;
                }
        }

        for (i = 0; i < vtoc->efi_nparts; i++) {

                if (vtoc->efi_parts[i].p_tag == V_UNASSIGNED ||
                    uuid_is_null((uchar_t *)&vtoc->efi_parts[i].p_guid))
                        continue;

                if (strncmp(path, UDISK_ROOT, strlen(UDISK_ROOT)) == 0)
                        (void) snprintf(slice_path, sizeof (slice_path),
                            "%s%s%d", path, "-part", i+1);
                else
                        (void) snprintf(slice_path, sizeof (slice_path),
                            "%s%s%d", path, isdigit(path[strlen(path)-1]) ?
                            "p" : "", i+1);

                err = check_slice(slice_path, cache, force, isspare);
                if (err)
                        break;
        }

        efi_free(vtoc);
        (void) close(fd);

        return (err);
}

static int
check_device(const char *path, boolean_t force,
             boolean_t isspare, boolean_t iswholedisk)
{
        static blkid_cache cache = NULL;

#ifdef HAVE_LIBBLKID
        /*
         * There is no easy way to add a correct blkid_put_cache() call,
         * memory will be reclaimed when the command exits.
         */
        if (cache == NULL) {
                int err;

                if ((err = blkid_get_cache(&cache, NULL)) != 0) {
                        check_error(err);
                        return -1;
                }

                if ((err = blkid_probe_all(cache)) != 0) {
                        blkid_put_cache(cache);
                        check_error(err);
                        return -1;
                }
        }
#endif /* HAVE_LIBBLKID */

        return check_disk(path, cache, force, isspare, iswholedisk);
}

/*
 * By "whole disk" we mean an entire physical disk (something we can
 * label, toggle the write cache on, etc.) as opposed to the full
 * capacity of a pseudo-device such as lofi or did.  We act as if we
 * are labeling the disk, which should be a pretty good test of whether
 * it's a viable device or not.  Returns B_TRUE if it is and B_FALSE if
 * it isn't.
 */
static boolean_t
is_whole_disk(const char *path)
{
        struct dk_gpt *label;
        int     fd;

        if ((fd = open(path, O_RDWR|O_DIRECT|O_EXCL)) < 0)
                return (B_FALSE);
        if (efi_alloc_and_init(fd, EFI_NUMPAR, &label) != 0) {
                (void) close(fd);
                return (B_FALSE);
        }
        efi_free(label);
        (void) close(fd);
        return (B_TRUE);
}

/*
 * This may be a shorthand device path or it could be total gibberish.
 * Check to see if it's a known device in /dev/, /dev/disk/by-id,
 * /dev/disk/by-label, /dev/disk/by-path, /dev/disk/by-uuid, or
 * /dev/disk/zpool/.  As part of this check, see if we've been given
 * an entire disk (minus the slice number).
 */
static int
is_shorthand_path(const char *arg, char *path,
                  struct stat64 *statbuf, boolean_t *wholedisk)
{
        if (zfs_resolve_shortname(arg, path, MAXPATHLEN) == 0) {
                *wholedisk = is_whole_disk(path);
                if (*wholedisk || (stat64(path, statbuf) == 0))
                        return (0);
        }

        strlcpy(path, arg, sizeof(path));
        memset(statbuf, 0, sizeof(*statbuf));
        *wholedisk = B_FALSE;

        return (ENOENT);
}

/*
 * Create a leaf vdev.  Determine if this is a file or a device.  If it's a
 * device, fill in the device id to make a complete nvlist.  Valid forms for a
 * leaf vdev are:
 *
 *      /dev/xxx        Complete disk path
 *      /xxx            Full path to file
 *      xxx             Shorthand for /dev/disk/yyy/xxx
 */
static nvlist_t *
make_leaf_vdev(const char *arg, uint64_t is_log)
{
        char path[MAXPATHLEN];
        struct stat64 statbuf;
        nvlist_t *vdev = NULL;
        char *type = NULL;
        boolean_t wholedisk = B_FALSE;
        int err;

        /*
         * Determine what type of vdev this is, and put the full path into
         * 'path'.  We detect whether this is a device of file afterwards by
         * checking the st_mode of the file.
         */
        if (arg[0] == '/') {
                /*
                 * Complete device or file path.  Exact type is determined by
                 * examining the file descriptor afterwards.  Symbolic links
                 * are resolved to their real paths for the is_whole_disk()
                 * and S_ISBLK/S_ISREG type checks.  However, we are careful
                 * to store the given path as ZPOOL_CONFIG_PATH to ensure we
                 * can leverage udev's persistent device labels.
                 */
                if (realpath(arg, path) == NULL) {
                        (void) fprintf(stderr,
                            gettext("cannot resolve path '%s'\n"), arg);
                        return (NULL);
                }

                wholedisk = is_whole_disk(path);
                if (!wholedisk && (stat64(path, &statbuf) != 0)) {
                        (void) fprintf(stderr,
                            gettext("cannot open '%s': %s\n"),
                            path, strerror(errno));
                        return (NULL);
                }

                /* After is_whole_disk() check restore original passed path */
                strlcpy(path, arg, MAXPATHLEN);
        } else {
                err = is_shorthand_path(arg, path, &statbuf, &wholedisk);
                if (err != 0) {
                        /*
                         * If we got ENOENT, then the user gave us
                         * gibberish, so try to direct them with a
                         * reasonable error message.  Otherwise,
                         * regurgitate strerror() since it's the best we
                         * can do.
                         */
                        if (err == ENOENT) {
                                (void) fprintf(stderr,
                                    gettext("cannot open '%s': no such "
                                    "device in %s\n"), arg, DISK_ROOT);
                                (void) fprintf(stderr,
                                    gettext("must be a full path or "
                                    "shorthand device name\n"));
                                return (NULL);
                        } else {
                                (void) fprintf(stderr,
                                    gettext("cannot open '%s': %s\n"),
                                    path, strerror(errno));
                                return (NULL);
                        }
                }
        }

        /*
         * Determine whether this is a device or a file.
         */
        if (wholedisk || S_ISBLK(statbuf.st_mode)) {
                type = VDEV_TYPE_DISK;
        } else if (S_ISREG(statbuf.st_mode)) {
                type = VDEV_TYPE_FILE;
        } else {
                (void) fprintf(stderr, gettext("cannot use '%s': must be a "
                    "block device or regular file\n"), path);
                return (NULL);
        }

        /*
         * Finally, we have the complete device or file, and we know that it is
         * acceptable to use.  Construct the nvlist to describe this vdev.  All
         * vdevs have a 'path' element, and devices also have a 'devid' element.
         */
        verify(nvlist_alloc(&vdev, NV_UNIQUE_NAME, 0) == 0);
        verify(nvlist_add_string(vdev, ZPOOL_CONFIG_PATH, path) == 0);
        verify(nvlist_add_string(vdev, ZPOOL_CONFIG_TYPE, type) == 0);
        verify(nvlist_add_uint64(vdev, ZPOOL_CONFIG_IS_LOG, is_log) == 0);
        if (strcmp(type, VDEV_TYPE_DISK) == 0)
                verify(nvlist_add_uint64(vdev, ZPOOL_CONFIG_WHOLE_DISK,
                    (uint64_t)wholedisk) == 0);

        return (vdev);
}

/*
 * Go through and verify the replication level of the pool is consistent.
 * Performs the following checks:
 *
 *      For the new spec, verifies that devices in mirrors and raidz are the
 *      same size.
 *
 *      If the current configuration already has inconsistent replication
 *      levels, ignore any other potential problems in the new spec.
 *
 *      Otherwise, make sure that the current spec (if there is one) and the new
 *      spec have consistent replication levels.
 */
typedef struct replication_level {
        char *zprl_type;
        uint64_t zprl_children;
        uint64_t zprl_parity;
} replication_level_t;

#define ZPOOL_FUZZ      (16 * 1024 * 1024)

/*
 * Given a list of toplevel vdevs, return the current replication level.  If
 * the config is inconsistent, then NULL is returned.  If 'fatal' is set, then
 * an error message will be displayed for each self-inconsistent vdev.
 */
static replication_level_t *
get_replication(nvlist_t *nvroot, boolean_t fatal)
{
        nvlist_t **top;
        uint_t t, toplevels;
        nvlist_t **child;
        uint_t c, children;
        nvlist_t *nv;
        char *type;
        replication_level_t lastrep = { 0 }, rep, *ret;
        boolean_t dontreport;

        ret = safe_malloc(sizeof (replication_level_t));

        verify(nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_CHILDREN,
            &top, &toplevels) == 0);

        lastrep.zprl_type = NULL;
        for (t = 0; t < toplevels; t++) {
                uint64_t is_log = B_FALSE;

                nv = top[t];

                /*
                 * For separate logs we ignore the top level vdev replication
                 * constraints.
                 */
                (void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_IS_LOG, &is_log);
                if (is_log)
                        continue;

                verify(nvlist_lookup_string(nv, ZPOOL_CONFIG_TYPE,
                    &type) == 0);
                if (nvlist_lookup_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN,
                    &child, &children) != 0) {
                        /*
                         * This is a 'file' or 'disk' vdev.
                         */
                        rep.zprl_type = type;
                        rep.zprl_children = 1;
                        rep.zprl_parity = 0;
                } else {
                        uint64_t vdev_size;

                        /*
                         * This is a mirror or RAID-Z vdev.  Go through and make
                         * sure the contents are all the same (files vs. disks),
                         * keeping track of the number of elements in the
                         * process.
                         *
                         * We also check that the size of each vdev (if it can
                         * be determined) is the same.
                         */
                        rep.zprl_type = type;
                        rep.zprl_children = 0;

                        if (strcmp(type, VDEV_TYPE_RAIDZ) == 0) {
                                verify(nvlist_lookup_uint64(nv,
                                    ZPOOL_CONFIG_NPARITY,
                                    &rep.zprl_parity) == 0);
                                assert(rep.zprl_parity != 0);
                        } else {
                                rep.zprl_parity = 0;
                        }

                        /*
                         * The 'dontreport' variable indicates that we've
                         * already reported an error for this spec, so don't
                         * bother doing it again.
                         */
                        type = NULL;
                        dontreport = 0;
                        vdev_size = -1ULL;
                        for (c = 0; c < children; c++) {
                                nvlist_t *cnv = child[c];
                                char *path;
                                struct stat64 statbuf;
                                uint64_t size = -1ULL;
                                char *childtype;
                                int fd, err;

                                rep.zprl_children++;

                                verify(nvlist_lookup_string(cnv,
                                    ZPOOL_CONFIG_TYPE, &childtype) == 0);

                                /*
                                 * If this is a replacing or spare vdev, then
                                 * get the real first child of the vdev.
                                 */
                                if (strcmp(childtype,
                                    VDEV_TYPE_REPLACING) == 0 ||
                                    strcmp(childtype, VDEV_TYPE_SPARE) == 0) {
                                        nvlist_t **rchild;
                                        uint_t rchildren;

                                        verify(nvlist_lookup_nvlist_array(cnv,
                                            ZPOOL_CONFIG_CHILDREN, &rchild,
                                            &rchildren) == 0);
                                        assert(rchildren == 2);
                                        cnv = rchild[0];

                                        verify(nvlist_lookup_string(cnv,
                                            ZPOOL_CONFIG_TYPE,
                                            &childtype) == 0);
                                }

                                verify(nvlist_lookup_string(cnv,
                                    ZPOOL_CONFIG_PATH, &path) == 0);

                                /*
                                 * If we have a raidz/mirror that combines disks
                                 * with files, report it as an error.
                                 */
                                if (!dontreport && type != NULL &&
                                    strcmp(type, childtype) != 0) {
                                        if (ret != NULL)
                                                free(ret);
                                        ret = NULL;
                                        if (fatal)
                                                vdev_error(gettext(
                                                    "mismatched replication "
                                                    "level: %s contains both "
                                                    "files and devices\n"),
                                                    rep.zprl_type);
                                        else
                                                return (NULL);
                                        dontreport = B_TRUE;
                                }

                                /*
                                 * According to stat(2), the value of 'st_size'
                                 * is undefined for block devices and character
                                 * devices.  But there is no effective way to
                                 * determine the real size in userland.
                                 *
                                 * Instead, we'll take advantage of an
                                 * implementation detail of spec_size().  If the
                                 * device is currently open, then we (should)
                                 * return a valid size.
                                 *
                                 * If we still don't get a valid size (indicated
                                 * by a size of 0 or MAXOFFSET_T), then ignore
                                 * this device altogether.
                                 */
                                if ((fd = open(path, O_RDONLY)) >= 0) {
                                        err = fstat64(fd, &statbuf);
                                        (void) close(fd);
                                } else {
                                        err = stat64(path, &statbuf);
                                }

                                if (err != 0 ||
                                    statbuf.st_size == 0 ||
                                    statbuf.st_size == MAXOFFSET_T)
                                        continue;

                                size = statbuf.st_size;

                                /*
                                 * Also make sure that devices and
                                 * slices have a consistent size.  If
                                 * they differ by a significant amount
                                 * (~16MB) then report an error.
                                 */
                                if (!dontreport &&
                                    (vdev_size != -1ULL &&
                                    (labs(size - vdev_size) >
                                    ZPOOL_FUZZ))) {
                                        if (ret != NULL)
                                                free(ret);
                                        ret = NULL;
                                        if (fatal)
                                                vdev_error(gettext(
                                                    "%s contains devices of "
                                                    "different sizes\n"),
                                                    rep.zprl_type);
                                        else
                                                return (NULL);
                                        dontreport = B_TRUE;
                                }

                                type = childtype;
                                vdev_size = size;
                        }
                }

                /*
                 * At this point, we have the replication of the last toplevel
                 * vdev in 'rep'.  Compare it to 'lastrep' to see if its
                 * different.
                 */
                if (lastrep.zprl_type != NULL) {
                        if (strcmp(lastrep.zprl_type, rep.zprl_type) != 0) {
                                if (ret != NULL)
                                        free(ret);
                                ret = NULL;
                                if (fatal)
                                        vdev_error(gettext(
                                            "mismatched replication level: "
                                            "both %s and %s vdevs are "
                                            "present\n"),
                                            lastrep.zprl_type, rep.zprl_type);
                                else
                                        return (NULL);
                        } else if (lastrep.zprl_parity != rep.zprl_parity) {
                                if (ret)
                                        free(ret);
                                ret = NULL;
                                if (fatal)
                                        vdev_error(gettext(
                                            "mismatched replication level: "
                                            "both %llu and %llu device parity "
                                            "%s vdevs are present\n"),
                                            lastrep.zprl_parity,
                                            rep.zprl_parity,
                                            rep.zprl_type);
                                else
                                        return (NULL);
                        } else if (lastrep.zprl_children != rep.zprl_children) {
                                if (ret)
                                        free(ret);
                                ret = NULL;
                                if (fatal)
                                        vdev_error(gettext(
                                            "mismatched replication level: "
                                            "both %llu-way and %llu-way %s "
                                            "vdevs are present\n"),
                                            lastrep.zprl_children,
                                            rep.zprl_children,
                                            rep.zprl_type);
                                else
                                        return (NULL);
                        }
                }
                lastrep = rep;
        }

        if (ret != NULL)
                *ret = rep;

        return (ret);
}

/*
 * Check the replication level of the vdev spec against the current pool.  Calls
 * get_replication() to make sure the new spec is self-consistent.  If the pool
 * has a consistent replication level, then we ignore any errors.  Otherwise,
 * report any difference between the two.
 */
static int
check_replication(nvlist_t *config, nvlist_t *newroot)
{
        nvlist_t **child;
        uint_t  children;
        replication_level_t *current = NULL, *new;
        int ret;

        /*
         * If we have a current pool configuration, check to see if it's
         * self-consistent.  If not, simply return success.
         */
        if (config != NULL) {
                nvlist_t *nvroot;

                verify(nvlist_lookup_nvlist(config, ZPOOL_CONFIG_VDEV_TREE,
                    &nvroot) == 0);
                if ((current = get_replication(nvroot, B_FALSE)) == NULL)
                        return (0);
        }
        /*
         * for spares there may be no children, and therefore no
         * replication level to check
         */
        if ((nvlist_lookup_nvlist_array(newroot, ZPOOL_CONFIG_CHILDREN,
            &child, &children) != 0) || (children == 0)) {
                free(current);
                return (0);
        }

        /*
         * If all we have is logs then there's no replication level to check.
         */
        if (num_logs(newroot) == children) {
                free(current);
                return (0);
        }

        /*
         * Get the replication level of the new vdev spec, reporting any
         * inconsistencies found.
         */
        if ((new = get_replication(newroot, B_TRUE)) == NULL) {
                free(current);
                return (-1);
        }

        /*
         * Check to see if the new vdev spec matches the replication level of
         * the current pool.
         */
        ret = 0;
        if (current != NULL) {
                if (strcmp(current->zprl_type, new->zprl_type) != 0) {
                        vdev_error(gettext(
                            "mismatched replication level: pool uses %s "
                            "and new vdev is %s\n"),
                            current->zprl_type, new->zprl_type);
                        ret = -1;
                } else if (current->zprl_parity != new->zprl_parity) {
                        vdev_error(gettext(
                            "mismatched replication level: pool uses %llu "
                            "device parity and new vdev uses %llu\n"),
                            current->zprl_parity, new->zprl_parity);
                        ret = -1;
                } else if (current->zprl_children != new->zprl_children) {
                        vdev_error(gettext(
                            "mismatched replication level: pool uses %llu-way "
                            "%s and new vdev uses %llu-way %s\n"),
                            current->zprl_children, current->zprl_type,
                            new->zprl_children, new->zprl_type);
                        ret = -1;
                }
        }

        free(new);
        if (current != NULL)
                free(current);

        return (ret);
}

static int
zero_label(char *path)
{
        const int size = 4096;
        char buf[size];
        int err, fd;

        if ((fd = open(path, O_WRONLY|O_EXCL)) < 0) {
                (void) fprintf(stderr, gettext("cannot open '%s': %s\n"),
                    path, strerror(errno));
                return (-1);
        }

        memset(buf, 0, size);
        err = write(fd, buf, size);
        (void) fdatasync(fd);
        (void) close(fd);

        if (err == -1) {
                (void) fprintf(stderr, gettext("cannot zero first %d bytes "
                    "of '%s': %s\n"), size, path, strerror(errno));
                return (-1);
        }

        if (err != size) {
                (void) fprintf(stderr, gettext("could only zero %d/%d bytes "
                    "of '%s'\n"), err, size, path);
                return (-1);
        }

        return 0;
}

/*
 * Go through and find any whole disks in the vdev specification, labelling them
 * as appropriate.  When constructing the vdev spec, we were unable to open this
 * device in order to provide a devid.  Now that we have labelled the disk and
 * know that slice 0 is valid, we can construct the devid now.
 *
 * If the disk was already labeled with an EFI label, we will have gotten the
 * devid already (because we were able to open the whole disk).  Otherwise, we
 * need to get the devid after we label the disk.
 */
static int
make_disks(zpool_handle_t *zhp, nvlist_t *nv)
{
        nvlist_t **child;
        uint_t c, children;
        char *type, *path, *diskname;
        char devpath[MAXPATHLEN];
        char udevpath[MAXPATHLEN];
        uint64_t wholedisk;
        struct stat64 statbuf;
        int ret;

        verify(nvlist_lookup_string(nv, ZPOOL_CONFIG_TYPE, &type) == 0);

        if (nvlist_lookup_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN,
            &child, &children) != 0) {

                if (strcmp(type, VDEV_TYPE_DISK) != 0)
                        return (0);

                /*
                 * We have a disk device.  If this is a whole disk write
                 * out the efi partition table, otherwise write zero's to
                 * the first 4k of the partition.  This is to ensure that
                 * libblkid will not misidentify the partition due to a
                 * magic value left by the previous filesystem.
                 */
                verify(!nvlist_lookup_string(nv, ZPOOL_CONFIG_PATH, &path));
                verify(!nvlist_lookup_uint64(nv, ZPOOL_CONFIG_WHOLE_DISK,
                    &wholedisk));

                if (!wholedisk) {
                        ret = zero_label(path);
                        return (ret);
                }

                if (realpath(path, devpath) == NULL) {
                        ret = errno;
                        (void) fprintf(stderr,
                            gettext("cannot resolve path '%s'\n"), path);
                        return (ret);
                }

                /*
                 * Remove any previously existing symlink from a udev path to
                 * the device before labeling the disk.  This makes
                 * zpool_label_disk_wait() truly wait for the new link to show
                 * up instead of returning if it finds an old link still in
                 * place.  Otherwise there is a window between when udev
                 * deletes and recreates the link during which access attempts
                 * will fail with ENOENT.
                 */
                zfs_append_partition(path, udevpath, sizeof (udevpath));
                if ((strncmp(udevpath, UDISK_ROOT, strlen(UDISK_ROOT)) == 0) &&
                    (lstat64(udevpath, &statbuf) == 0) &&
                    S_ISLNK(statbuf.st_mode))
                        (void) unlink(udevpath);

                diskname = strrchr(devpath, '/');
                assert(diskname != NULL);
                diskname++;
                if (zpool_label_disk(g_zfs, zhp, diskname) == -1)
                        return (-1);

                /*
                 * Now we've labeled the disk and the partitions have been
                 * created.  We still need to wait for udev to create the
                 * symlinks to those partitions.
                 */
                if ((ret = zpool_label_disk_wait(udevpath, 1000)) != 0) {
                        (void) fprintf(stderr,
                            gettext( "cannot resolve path '%s'\n"), udevpath);
                        return (-1);
                }

                /*
                 * Update the path to refer to FIRST_SLICE.  The presence of
                 * the 'whole_disk' field indicates to the CLI that we should
                 * chop off the slice number when displaying the device in
                 * future output.
                 */
                verify(nvlist_add_string(nv, ZPOOL_CONFIG_PATH, udevpath) == 0);

                /* Just in case this partition already existed. */
                (void) zero_label(udevpath);

                return (0);
        }

        for (c = 0; c < children; c++)
                if ((ret = make_disks(zhp, child[c])) != 0)
                        return (ret);

        if (nvlist_lookup_nvlist_array(nv, ZPOOL_CONFIG_SPARES,
            &child, &children) == 0)
                for (c = 0; c < children; c++)
                        if ((ret = make_disks(zhp, child[c])) != 0)
                                return (ret);

        if (nvlist_lookup_nvlist_array(nv, ZPOOL_CONFIG_L2CACHE,
            &child, &children) == 0)
                for (c = 0; c < children; c++)
                        if ((ret = make_disks(zhp, child[c])) != 0)
                                return (ret);

        return (0);
}

/*
 * Determine if the given path is a hot spare within the given configuration.
 */
static boolean_t
is_spare(nvlist_t *config, const char *path)
{
        int fd;
        pool_state_t state;
        char *name = NULL;
        nvlist_t *label;
        uint64_t guid, spareguid;
        nvlist_t *nvroot;
        nvlist_t **spares;
        uint_t i, nspares;
        boolean_t inuse;

        if ((fd = open(path, O_RDONLY|O_EXCL)) < 0)
                return (B_FALSE);

        if (zpool_in_use(g_zfs, fd, &state, &name, &inuse) != 0 ||
            !inuse ||
            state != POOL_STATE_SPARE ||
            zpool_read_label(fd, &label) != 0) {
                free(name);
                (void) close(fd);
                return (B_FALSE);
        }
        free(name);
        (void) close(fd);

        verify(nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID, &guid) == 0);
        nvlist_free(label);

        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++) {
                        verify(nvlist_lookup_uint64(spares[i],
                            ZPOOL_CONFIG_GUID, &spareguid) == 0);
                        if (spareguid == guid)
                                return (B_TRUE);
                }
        }

        return (B_FALSE);
}

/*
 * Go through and find any devices that are in use.  We rely on libdiskmgt for
 * the majority of this task.
 */
static int
check_in_use(nvlist_t *config, nvlist_t *nv, boolean_t force,
    boolean_t replacing, boolean_t isspare)
{
        nvlist_t **child;
        uint_t c, children;
        char *type, *path;
        int ret = 0;
        char buf[MAXPATHLEN];
        uint64_t wholedisk = B_FALSE;

        verify(nvlist_lookup_string(nv, ZPOOL_CONFIG_TYPE, &type) == 0);

        if (nvlist_lookup_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN,
            &child, &children) != 0) {

                verify(!nvlist_lookup_string(nv, ZPOOL_CONFIG_PATH, &path));
                if (strcmp(type, VDEV_TYPE_DISK) == 0)
                        verify(!nvlist_lookup_uint64(nv,
                               ZPOOL_CONFIG_WHOLE_DISK, &wholedisk));

                /*
                 * As a generic check, we look to see if this is a replace of a
                 * hot spare within the same pool.  If so, we allow it
                 * regardless of what libblkid or zpool_in_use() says.
                 */
                if (replacing) {
                        if (wholedisk)
                                (void) snprintf(buf, sizeof (buf), "%ss0",
                                    path);
                        else
                                (void) strlcpy(buf, path, sizeof (buf));

                        if (is_spare(config, buf))
                                return (0);
                }

                if (strcmp(type, VDEV_TYPE_DISK) == 0)
                        ret = check_device(path, force, isspare, wholedisk);

                if (strcmp(type, VDEV_TYPE_FILE) == 0)
                        ret = check_file(path, force, isspare);

                return (ret);
        }

        for (c = 0; c < children; c++)
                if ((ret = check_in_use(config, child[c], force,
                    replacing, B_FALSE)) != 0)
                        return (ret);

        if (nvlist_lookup_nvlist_array(nv, ZPOOL_CONFIG_SPARES,
            &child, &children) == 0)
                for (c = 0; c < children; c++)
                        if ((ret = check_in_use(config, child[c], force,
                            replacing, B_TRUE)) != 0)
                                return (ret);

        if (nvlist_lookup_nvlist_array(nv, ZPOOL_CONFIG_L2CACHE,
            &child, &children) == 0)
                for (c = 0; c < children; c++)
                        if ((ret = check_in_use(config, child[c], force,
                            replacing, B_FALSE)) != 0)
                                return (ret);

        return (0);
}

static const char *
is_grouping(const char *type, int *mindev, int *maxdev)
{
        if (strncmp(type, "raidz", 5) == 0) {
                const char *p = type + 5;
                char *end;
                long nparity;

                if (*p == '\0') {
                        nparity = 1;
                } else if (*p == '0') {
                        return (NULL); /* no zero prefixes allowed */
                } else {
                        errno = 0;
                        nparity = strtol(p, &end, 10);
                        if (errno != 0 || nparity < 1 || nparity >= 255 ||
                            *end != '\0')
                                return (NULL);
                }

                if (mindev != NULL)
                        *mindev = nparity + 1;
                if (maxdev != NULL)
                        *maxdev = 255;
                return (VDEV_TYPE_RAIDZ);
        }

        if (maxdev != NULL)
                *maxdev = INT_MAX;

        if (strcmp(type, "mirror") == 0) {
                if (mindev != NULL)
                        *mindev = 2;
                return (VDEV_TYPE_MIRROR);
        }

        if (strcmp(type, "spare") == 0) {
                if (mindev != NULL)
                        *mindev = 1;
                return (VDEV_TYPE_SPARE);
        }

        if (strcmp(type, "log") == 0) {
                if (mindev != NULL)
                        *mindev = 1;
                return (VDEV_TYPE_LOG);
        }

        if (strcmp(type, "cache") == 0) {
                if (mindev != NULL)
                        *mindev = 1;
                return (VDEV_TYPE_L2CACHE);
        }

        return (NULL);
}

/*
 * Construct a syntactically valid vdev specification,
 * and ensure that all devices and files exist and can be opened.
 * Note: we don't bother freeing anything in the error paths
 * because the program is just going to exit anyway.
 */
nvlist_t *
construct_spec(int argc, char **argv)
{
        nvlist_t *nvroot, *nv, **top, **spares, **l2cache;
        int t, toplevels, mindev, maxdev, nspares, nlogs, nl2cache;
        const char *type;
        uint64_t is_log;
        boolean_t seen_logs;

        top = NULL;
        toplevels = 0;
        spares = NULL;
        l2cache = NULL;
        nspares = 0;
        nlogs = 0;
        nl2cache = 0;
        is_log = B_FALSE;
        seen_logs = B_FALSE;

        while (argc > 0) {
                nv = NULL;

                /*
                 * If it's a mirror or raidz, the subsequent arguments are
                 * its leaves -- until we encounter the next mirror or raidz.
                 */
                if ((type = is_grouping(argv[0], &mindev, &maxdev)) != NULL) {
                        nvlist_t **child = NULL;
                        int c, children = 0;

                        if (strcmp(type, VDEV_TYPE_SPARE) == 0) {
                                if (spares != NULL) {
                                        (void) fprintf(stderr,
                                            gettext("invalid vdev "
                                            "specification: 'spare' can be "
                                            "specified only once\n"));
                                        return (NULL);
                                }
                                is_log = B_FALSE;
                        }

                        if (strcmp(type, VDEV_TYPE_LOG) == 0) {
                                if (seen_logs) {
                                        (void) fprintf(stderr,
                                            gettext("invalid vdev "
                                            "specification: 'log' can be "
                                            "specified only once\n"));
                                        return (NULL);
                                }
                                seen_logs = B_TRUE;
                                is_log = B_TRUE;
                                argc--;
                                argv++;
                                /*
                                 * A log is not a real grouping device.
                                 * We just set is_log and continue.
                                 */
                                continue;
                        }

                        if (strcmp(type, VDEV_TYPE_L2CACHE) == 0) {
                                if (l2cache != NULL) {
                                        (void) fprintf(stderr,
                                            gettext("invalid vdev "
                                            "specification: 'cache' can be "
                                            "specified only once\n"));
                                        return (NULL);
                                }
                                is_log = B_FALSE;
                        }

                        if (is_log) {
                                if (strcmp(type, VDEV_TYPE_MIRROR) != 0) {
                                        (void) fprintf(stderr,
                                            gettext("invalid vdev "
                                            "specification: unsupported 'log' "
                                            "device: %s\n"), type);
                                        return (NULL);
                                }
                                nlogs++;
                        }

                        for (c = 1; c < argc; c++) {
                                if (is_grouping(argv[c], NULL, NULL) != NULL)
                                        break;
                                children++;
                                child = realloc(child,
                                    children * sizeof (nvlist_t *));
                                if (child == NULL)
                                        zpool_no_memory();
                                if ((nv = make_leaf_vdev(argv[c], B_FALSE))
                                    == NULL)
                                        return (NULL);
                                child[children - 1] = nv;
                        }

                        if (children < mindev) {
                                (void) fprintf(stderr, gettext("invalid vdev "
                                    "specification: %s requires at least %d "
                                    "devices\n"), argv[0], mindev);
                                return (NULL);
                        }

                        if (children > maxdev) {
                                (void) fprintf(stderr, gettext("invalid vdev "
                                    "specification: %s supports no more than "
                                    "%d devices\n"), argv[0], maxdev);
                                return (NULL);
                        }

                        argc -= c;
                        argv += c;

                        if (strcmp(type, VDEV_TYPE_SPARE) == 0) {
                                spares = child;
                                nspares = children;
                                continue;
                        } else if (strcmp(type, VDEV_TYPE_L2CACHE) == 0) {
                                l2cache = child;
                                nl2cache = children;
                                continue;
                        } else {
                                verify(nvlist_alloc(&nv, NV_UNIQUE_NAME,
                                    0) == 0);
                                verify(nvlist_add_string(nv, ZPOOL_CONFIG_TYPE,
                                    type) == 0);
                                verify(nvlist_add_uint64(nv,
                                    ZPOOL_CONFIG_IS_LOG, is_log) == 0);
                                if (strcmp(type, VDEV_TYPE_RAIDZ) == 0) {
                                        verify(nvlist_add_uint64(nv,
                                            ZPOOL_CONFIG_NPARITY,
                                            mindev - 1) == 0);
                                }
                                verify(nvlist_add_nvlist_array(nv,
                                    ZPOOL_CONFIG_CHILDREN, child,
                                    children) == 0);

                                for (c = 0; c < children; c++)
                                        nvlist_free(child[c]);
                                free(child);
                        }
                } else {
                        /*
                         * We have a device.  Pass off to make_leaf_vdev() to
                         * construct the appropriate nvlist describing the vdev.
                         */
                        if ((nv = make_leaf_vdev(argv[0], is_log)) == NULL)
                                return (NULL);
                        if (is_log)
                                nlogs++;
                        argc--;
                        argv++;
                }

                toplevels++;
                top = realloc(top, toplevels * sizeof (nvlist_t *));
                if (top == NULL)
                        zpool_no_memory();
                top[toplevels - 1] = nv;
        }

        if (toplevels == 0 && nspares == 0 && nl2cache == 0) {
                (void) fprintf(stderr, gettext("invalid vdev "
                    "specification: at least one toplevel vdev must be "
                    "specified\n"));
                return (NULL);
        }

        if (seen_logs && nlogs == 0) {
                (void) fprintf(stderr, gettext("invalid vdev specification: "
                    "log requires at least 1 device\n"));
                return (NULL);
        }

        /*
         * Finally, create nvroot and add all top-level vdevs to it.
         */
        verify(nvlist_alloc(&nvroot, NV_UNIQUE_NAME, 0) == 0);
        verify(nvlist_add_string(nvroot, ZPOOL_CONFIG_TYPE,
            VDEV_TYPE_ROOT) == 0);
        verify(nvlist_add_nvlist_array(nvroot, ZPOOL_CONFIG_CHILDREN,
            top, toplevels) == 0);
        if (nspares != 0)
                verify(nvlist_add_nvlist_array(nvroot, ZPOOL_CONFIG_SPARES,
                    spares, nspares) == 0);
        if (nl2cache != 0)
                verify(nvlist_add_nvlist_array(nvroot, ZPOOL_CONFIG_L2CACHE,
                    l2cache, nl2cache) == 0);

        for (t = 0; t < toplevels; t++)
                nvlist_free(top[t]);
        for (t = 0; t < nspares; t++)
                nvlist_free(spares[t]);
        for (t = 0; t < nl2cache; t++)
                nvlist_free(l2cache[t]);
        if (spares)
                free(spares);
        if (l2cache)
                free(l2cache);
        free(top);

        return (nvroot);
}

nvlist_t *
split_mirror_vdev(zpool_handle_t *zhp, char *newname, nvlist_t *props,
    splitflags_t flags, int argc, char **argv)
{
        nvlist_t *newroot = NULL, **child;
        uint_t c, children;

        if (argc > 0) {
                if ((newroot = construct_spec(argc, argv)) == NULL) {
                        (void) fprintf(stderr, gettext("Unable to build a "
                            "pool from the specified devices\n"));
                        return (NULL);
                }

                if (!flags.dryrun && make_disks(zhp, newroot) != 0) {
                        nvlist_free(newroot);
                        return (NULL);
                }

                /* avoid any tricks in the spec */
                verify(nvlist_lookup_nvlist_array(newroot,
                    ZPOOL_CONFIG_CHILDREN, &child, &children) == 0);
                for (c = 0; c < children; c++) {
                        char *path;
                        const char *type;
                        int min, max;

                        verify(nvlist_lookup_string(child[c],
                            ZPOOL_CONFIG_PATH, &path) == 0);
                        if ((type = is_grouping(path, &min, &max)) != NULL) {
                                (void) fprintf(stderr, gettext("Cannot use "
                                    "'%s' as a device for splitting\n"), type);
                                nvlist_free(newroot);
                                return (NULL);
                        }
                }
        }

        if (zpool_vdev_split(zhp, newname, &newroot, props, flags) != 0) {
                if (newroot != NULL)
                        nvlist_free(newroot);
                return (NULL);
        }

        return (newroot);
}

/*
 * Get and validate the contents of the given vdev specification.  This ensures
 * that the nvlist returned is well-formed, that all the devices exist, and that
 * they are not currently in use by any other known consumer.  The 'poolconfig'
 * parameter is the current configuration of the pool when adding devices
 * existing pool, and is used to perform additional checks, such as changing the
 * replication level of the pool.  It can be 'NULL' to indicate that this is a
 * new pool.  The 'force' flag controls whether devices should be forcefully
 * added, even if they appear in use.
 */
nvlist_t *
make_root_vdev(zpool_handle_t *zhp, int force, int check_rep,
    boolean_t replacing, boolean_t dryrun, int argc, char **argv)
{
        nvlist_t *newroot;
        nvlist_t *poolconfig = NULL;
        is_force = force;

        /*
         * Construct the vdev specification.  If this is successful, we know
         * that we have a valid specification, and that all devices can be
         * opened.
         */
        if ((newroot = construct_spec(argc, argv)) == NULL)
                return (NULL);

        if (zhp && ((poolconfig = zpool_get_config(zhp, NULL)) == NULL))
                return (NULL);

        /*
         * Validate each device to make sure that its not shared with another
         * subsystem.  We do this even if 'force' is set, because there are some
         * uses (such as a dedicated dump device) that even '-f' cannot
         * override.
         */
        if (check_in_use(poolconfig, newroot, force, replacing, B_FALSE) != 0) {
                nvlist_free(newroot);
                return (NULL);
        }

        /*
         * Check the replication level of the given vdevs and report any errors
         * found.  We include the existing pool spec, if any, as we need to
         * catch changes against the existing replication level.
         */
        if (check_rep && check_replication(poolconfig, newroot) != 0) {
                nvlist_free(newroot);
                return (NULL);
        }

        /*
         * Run through the vdev specification and label any whole disks found.
         */
        if (!dryrun && make_disks(zhp, newroot) != 0) {
                nvlist_free(newroot);
                return (NULL);
        }

        return (newroot);
}