FreeBSD: Lock vnode in zfs_ioctl()

[zfs.git] / cmd / zpool_influxdb / zpool_influxdb.c

/*
 * Gather top-level ZFS pool and resilver/scan statistics and print using
 * influxdb line protocol
 * usage: [options] [pool_name]
 * where options are:
 *   --execd, -e           run in telegraf execd input plugin mode, [CR] on
 *                         stdin causes a sample to be printed and wait for
 *                         the next [CR]
 *   --no-histograms, -n   don't print histogram data (reduces cardinality
 *                         if you don't care about histograms)
 *   --sum-histogram-buckets, -s sum histogram bucket values
 *
 * To integrate into telegraf use one of:
 * 1. the `inputs.execd` plugin with the `--execd` option
 * 2. the `inputs.exec` plugin to simply run with no options
 *
 * NOTE: libzfs is an unstable interface. YMMV.
 *
 * The design goals of this software include:
 * + be as lightweight as possible
 * + reduce the number of external dependencies as far as possible, hence
 *   there is no dependency on a client library for managing the metric
 *   collection -- info is printed, KISS
 * + broken pools or kernel bugs can cause this process to hang in an
 *   unkillable state. For this reason, it is best to keep the damage limited
 *   to a small process like zpool_influxdb rather than a larger collector.
 *
 * Copyright 2018-2020 Richard Elling
 *
 * This software is dual-licensed MIT and CDDL.
 *
 * The MIT License (MIT)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * 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.
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License Version 1.0 (CDDL-1.0).
 * You can obtain a copy of the license from the top-level file
 * "OPENSOLARIS.LICENSE" or at <http://opensource.org/licenses/CDDL-1.0>.
 * You may not use this file except in compliance with the license.
 *
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * CDDL HEADER END
 */
#include <string.h>
#include <getopt.h>
#include <stdio.h>
#include <stdint.h>
#include <inttypes.h>
#include <libzfs.h>

#define POOL_MEASUREMENT        "zpool_stats"
#define SCAN_MEASUREMENT        "zpool_scan_stats"
#define VDEV_MEASUREMENT        "zpool_vdev_stats"
#define POOL_LATENCY_MEASUREMENT        "zpool_latency"
#define POOL_QUEUE_MEASUREMENT  "zpool_vdev_queue"
#define MIN_LAT_INDEX   10  /* minimum latency index 10 = 1024ns */
#define POOL_IO_SIZE_MEASUREMENT        "zpool_io_size"
#define MIN_SIZE_INDEX  9  /* minimum size index 9 = 512 bytes */

/* global options */
int execd_mode = 0;
int no_histograms = 0;
int sum_histogram_buckets = 0;
char metric_data_type = 'u';
uint64_t metric_value_mask = UINT64_MAX;
uint64_t timestamp = 0;
int complained_about_sync = 0;
const char *tags = "";

typedef int (*stat_printer_f)(nvlist_t *, const char *, const char *);

/*
 * influxdb line protocol rules for escaping are important because the
 * zpool name can include characters that need to be escaped
 *
 * caller is responsible for freeing result
 */
static char *
escape_string(const char *s)
{
        const char *c;
        char *d;
        char *t = (char *)malloc(ZFS_MAX_DATASET_NAME_LEN * 2);
        if (t == NULL) {
                fprintf(stderr, "error: cannot allocate memory\n");
                exit(1);
        }

        for (c = s, d = t; *c != '\0'; c++, d++) {
                switch (*c) {
                case ' ':
                case ',':
                case '=':
                case '\\':
                        *d++ = '\\';
                        zfs_fallthrough;
                default:
                        *d = *c;
                }
        }
        *d = '\0';
        return (t);
}

/*
 * print key=value where value is a uint64_t
 */
static void
print_kv(const char *key, uint64_t value)
{
        printf("%s=%llu%c", key,
            (u_longlong_t)value & metric_value_mask, metric_data_type);
}

/*
 * print_scan_status() prints the details as often seen in the "zpool status"
 * output. However, unlike the zpool command, which is intended for humans,
 * this output is suitable for long-term tracking in influxdb.
 * TODO: update to include issued scan data
 */
static int
print_scan_status(nvlist_t *nvroot, const char *pool_name)
{
        uint_t c;
        int64_t elapsed;
        uint64_t examined, pass_exam, paused_time, paused_ts, rate;
        uint64_t remaining_time;
        pool_scan_stat_t *ps = NULL;
        double pct_done;
        const char *const state[DSS_NUM_STATES] = {
            "none", "scanning", "finished", "canceled"};
        const char *func;

        (void) nvlist_lookup_uint64_array(nvroot,
            ZPOOL_CONFIG_SCAN_STATS,
            (uint64_t **)&ps, &c);

        /*
         * ignore if there are no stats
         */
        if (ps == NULL)
                return (0);

        /*
         * return error if state is bogus
         */
        if (ps->pss_state >= DSS_NUM_STATES ||
            ps->pss_func >= POOL_SCAN_FUNCS) {
                if (complained_about_sync % 1000 == 0) {
                        fprintf(stderr, "error: cannot decode scan stats: "
                            "ZFS is out of sync with compiled zpool_influxdb");
                        complained_about_sync++;
                }
                return (1);
        }

        switch (ps->pss_func) {
        case POOL_SCAN_NONE:
                func = "none_requested";
                break;
        case POOL_SCAN_SCRUB:
                func = "scrub";
                break;
        case POOL_SCAN_RESILVER:
                func = "resilver";
                break;
#ifdef POOL_SCAN_REBUILD
        case POOL_SCAN_REBUILD:
                func = "rebuild";
                break;
#endif
        default:
                func = "scan";
        }

        /* overall progress */
        examined = ps->pss_examined ? ps->pss_examined : 1;
        pct_done = 0.0;
        if (ps->pss_to_examine > 0)
                pct_done = 100.0 * examined / ps->pss_to_examine;

#ifdef EZFS_SCRUB_PAUSED
        paused_ts = ps->pss_pass_scrub_pause;
        paused_time = ps->pss_pass_scrub_spent_paused;
#else
        paused_ts = 0;
        paused_time = 0;
#endif

        /* calculations for this pass */
        if (ps->pss_state == DSS_SCANNING) {
                elapsed = (int64_t)time(NULL) - (int64_t)ps->pss_pass_start -
                    (int64_t)paused_time;
                elapsed = (elapsed > 0) ? elapsed : 1;
                pass_exam = ps->pss_pass_exam ? ps->pss_pass_exam : 1;
                rate = pass_exam / elapsed;
                rate = (rate > 0) ? rate : 1;
                remaining_time = ps->pss_to_examine - examined / rate;
        } else {
                elapsed =
                    (int64_t)ps->pss_end_time - (int64_t)ps->pss_pass_start -
                    (int64_t)paused_time;
                elapsed = (elapsed > 0) ? elapsed : 1;
                pass_exam = ps->pss_pass_exam ? ps->pss_pass_exam : 1;
                rate = pass_exam / elapsed;
                remaining_time = 0;
        }
        rate = rate ? rate : 1;

        /* influxdb line protocol format: "tags metrics timestamp" */
        printf("%s%s,function=%s,name=%s,state=%s ",
            SCAN_MEASUREMENT, tags, func, pool_name, state[ps->pss_state]);
        print_kv("end_ts", ps->pss_end_time);
        print_kv(",errors", ps->pss_errors);
        print_kv(",examined", examined);
        print_kv(",skipped", ps->pss_skipped);
        print_kv(",issued", ps->pss_issued);
        print_kv(",pass_examined", pass_exam);
        print_kv(",pass_issued", ps->pss_pass_issued);
        print_kv(",paused_ts", paused_ts);
        print_kv(",paused_t", paused_time);
        printf(",pct_done=%.2f", pct_done);
        print_kv(",processed", ps->pss_processed);
        print_kv(",rate", rate);
        print_kv(",remaining_t", remaining_time);
        print_kv(",start_ts", ps->pss_start_time);
        print_kv(",to_examine", ps->pss_to_examine);
        printf(" %llu\n", (u_longlong_t)timestamp);
        return (0);
}

/*
 * get a vdev name that corresponds to the top-level vdev names
 * printed by `zpool status`
 */
static char *
get_vdev_name(nvlist_t *nvroot, const char *parent_name)
{
        static char vdev_name[256];
        uint64_t vdev_id = 0;

        const char *vdev_type = "unknown";
        (void) nvlist_lookup_string(nvroot, ZPOOL_CONFIG_TYPE, &vdev_type);

        if (nvlist_lookup_uint64(
            nvroot, ZPOOL_CONFIG_ID, &vdev_id) != 0)
                vdev_id = UINT64_MAX;

        if (parent_name == NULL) {
                (void) snprintf(vdev_name, sizeof (vdev_name), "%s",
                    vdev_type);
        } else {
                (void) snprintf(vdev_name, sizeof (vdev_name),
                    "%.220s/%s-%llu",
                    parent_name, vdev_type, (u_longlong_t)vdev_id);
        }
        return (vdev_name);
}

/*
 * get a string suitable for an influxdb tag that describes this vdev
 *
 * By default only the vdev hierarchical name is shown, separated by '/'
 * If the vdev has an associated path, which is typical of leaf vdevs,
 * then the path is added.
 * It would be nice to have the devid instead of the path, but under
 * Linux we cannot be sure a devid will exist and we'd rather have
 * something than nothing, so we'll use path instead.
 */
static char *
get_vdev_desc(nvlist_t *nvroot, const char *parent_name)
{
        static char vdev_desc[2 * MAXPATHLEN];
        char vdev_value[MAXPATHLEN];
        char *s, *t;

        const char *vdev_type = "unknown";
        uint64_t vdev_id = UINT64_MAX;
        const char *vdev_path = NULL;
        (void) nvlist_lookup_string(nvroot, ZPOOL_CONFIG_TYPE, &vdev_type);
        (void) nvlist_lookup_uint64(nvroot, ZPOOL_CONFIG_ID, &vdev_id);
        (void) nvlist_lookup_string(nvroot, ZPOOL_CONFIG_PATH, &vdev_path);

        if (parent_name == NULL) {
                s = escape_string(vdev_type);
                (void) snprintf(vdev_value, sizeof (vdev_value), "vdev=%s", s);
                free(s);
        } else {
                s = escape_string((char *)parent_name);
                t = escape_string(vdev_type);
                (void) snprintf(vdev_value, sizeof (vdev_value),
                    "vdev=%s/%s-%llu", s, t, (u_longlong_t)vdev_id);
                free(s);
                free(t);
        }
        if (vdev_path == NULL) {
                (void) snprintf(vdev_desc, sizeof (vdev_desc), "%s",
                    vdev_value);
        } else {
                s = escape_string(vdev_path);
                (void) snprintf(vdev_desc, sizeof (vdev_desc), "path=%s,%s",
                    s, vdev_value);
                free(s);
        }
        return (vdev_desc);
}

/*
 * vdev summary stats are a combination of the data shown by
 * `zpool status` and `zpool list -v`
 */
static int
print_summary_stats(nvlist_t *nvroot, const char *pool_name,
    const char *parent_name)
{
        uint_t c;
        vdev_stat_t *vs;
        char *vdev_desc = NULL;
        vdev_desc = get_vdev_desc(nvroot, parent_name);
        if (nvlist_lookup_uint64_array(nvroot, ZPOOL_CONFIG_VDEV_STATS,
            (uint64_t **)&vs, &c) != 0) {
                return (1);
        }
        printf("%s%s,name=%s,state=%s,%s ", POOL_MEASUREMENT, tags,
            pool_name, zpool_state_to_name((vdev_state_t)vs->vs_state,
            (vdev_aux_t)vs->vs_aux), vdev_desc);
        print_kv("alloc", vs->vs_alloc);
        print_kv(",free", vs->vs_space - vs->vs_alloc);
        print_kv(",size", vs->vs_space);
        print_kv(",read_bytes", vs->vs_bytes[ZIO_TYPE_READ]);
        print_kv(",read_errors", vs->vs_read_errors);
        print_kv(",read_ops", vs->vs_ops[ZIO_TYPE_READ]);
        print_kv(",write_bytes", vs->vs_bytes[ZIO_TYPE_WRITE]);
        print_kv(",write_errors", vs->vs_write_errors);
        print_kv(",write_ops", vs->vs_ops[ZIO_TYPE_WRITE]);
        print_kv(",checksum_errors", vs->vs_checksum_errors);
        print_kv(",fragmentation", vs->vs_fragmentation);
        printf(" %llu\n", (u_longlong_t)timestamp);
        return (0);
}

/*
 * vdev latency stats are histograms stored as nvlist arrays of uint64.
 * Latency stats include the ZIO scheduler classes plus lower-level
 * vdev latencies.
 *
 * In many cases, the top-level "root" view obscures the underlying
 * top-level vdev operations. For example, if a pool has a log, special,
 * or cache device, then each can behave very differently. It is useful
 * to see how each is responding.
 */
static int
print_vdev_latency_stats(nvlist_t *nvroot, const char *pool_name,
    const char *parent_name)
{
        uint_t c, end = 0;
        nvlist_t *nv_ex;
        char *vdev_desc = NULL;

        /* short_names become part of the metric name and are influxdb-ready */
        struct lat_lookup {
            const char *name;
            const char *short_name;
            uint64_t sum;
            uint64_t *array;
        };
        struct lat_lookup lat_type[] = {
            {ZPOOL_CONFIG_VDEV_TOT_R_LAT_HISTO,   "total_read", 0},
            {ZPOOL_CONFIG_VDEV_TOT_W_LAT_HISTO,   "total_write", 0},
            {ZPOOL_CONFIG_VDEV_DISK_R_LAT_HISTO,  "disk_read", 0},
            {ZPOOL_CONFIG_VDEV_DISK_W_LAT_HISTO,  "disk_write", 0},
            {ZPOOL_CONFIG_VDEV_SYNC_R_LAT_HISTO,  "sync_read", 0},
            {ZPOOL_CONFIG_VDEV_SYNC_W_LAT_HISTO,  "sync_write", 0},
            {ZPOOL_CONFIG_VDEV_ASYNC_R_LAT_HISTO, "async_read", 0},
            {ZPOOL_CONFIG_VDEV_ASYNC_W_LAT_HISTO, "async_write", 0},
            {ZPOOL_CONFIG_VDEV_SCRUB_LAT_HISTO,   "scrub", 0},
#ifdef ZPOOL_CONFIG_VDEV_TRIM_LAT_HISTO
            {ZPOOL_CONFIG_VDEV_TRIM_LAT_HISTO,    "trim", 0},
#endif
            {ZPOOL_CONFIG_VDEV_REBUILD_LAT_HISTO,    "rebuild", 0},
            {NULL,      NULL}
        };

        if (nvlist_lookup_nvlist(nvroot,
            ZPOOL_CONFIG_VDEV_STATS_EX, &nv_ex) != 0) {
                return (6);
        }

        vdev_desc = get_vdev_desc(nvroot, parent_name);

        for (int i = 0; lat_type[i].name; i++) {
                if (nvlist_lookup_uint64_array(nv_ex,
                    lat_type[i].name, &lat_type[i].array, &c) != 0) {
                        fprintf(stderr, "error: can't get %s\n",
                            lat_type[i].name);
                        return (3);
                }
                /* end count count, all of the arrays are the same size */
                end = c - 1;
        }

        for (int bucket = 0; bucket <= end; bucket++) {
                if (bucket < MIN_LAT_INDEX) {
                        /* don't print, but collect the sum */
                        for (int i = 0; lat_type[i].name; i++) {
                                lat_type[i].sum += lat_type[i].array[bucket];
                        }
                        continue;
                }
                if (bucket < end) {
                        printf("%s%s,le=%0.6f,name=%s,%s ",
                            POOL_LATENCY_MEASUREMENT, tags,
                            (float)(1ULL << bucket) * 1e-9,
                            pool_name, vdev_desc);
                } else {
                        printf("%s%s,le=+Inf,name=%s,%s ",
                            POOL_LATENCY_MEASUREMENT, tags, pool_name,
                            vdev_desc);
                }
                for (int i = 0; lat_type[i].name; i++) {
                        if (bucket <= MIN_LAT_INDEX || sum_histogram_buckets) {
                                lat_type[i].sum += lat_type[i].array[bucket];
                        } else {
                                lat_type[i].sum = lat_type[i].array[bucket];
                        }
                        print_kv(lat_type[i].short_name, lat_type[i].sum);
                        if (lat_type[i + 1].name != NULL) {
                                printf(",");
                        }
                }
                printf(" %llu\n", (u_longlong_t)timestamp);
        }
        return (0);
}

/*
 * vdev request size stats are histograms stored as nvlist arrays of uint64.
 * Request size stats include the ZIO scheduler classes plus lower-level
 * vdev sizes. Both independent (ind) and aggregated (agg) sizes are reported.
 *
 * In many cases, the top-level "root" view obscures the underlying
 * top-level vdev operations. For example, if a pool has a log, special,
 * or cache device, then each can behave very differently. It is useful
 * to see how each is responding.
 */
static int
print_vdev_size_stats(nvlist_t *nvroot, const char *pool_name,
    const char *parent_name)
{
        uint_t c, end = 0;
        nvlist_t *nv_ex;
        char *vdev_desc = NULL;

        /* short_names become the field name */
        struct size_lookup {
            const char *name;
            const char *short_name;
            uint64_t sum;
            uint64_t *array;
        };
        struct size_lookup size_type[] = {
            {ZPOOL_CONFIG_VDEV_SYNC_IND_R_HISTO,   "sync_read_ind"},
            {ZPOOL_CONFIG_VDEV_SYNC_IND_W_HISTO,   "sync_write_ind"},
            {ZPOOL_CONFIG_VDEV_ASYNC_IND_R_HISTO,  "async_read_ind"},
            {ZPOOL_CONFIG_VDEV_ASYNC_IND_W_HISTO,  "async_write_ind"},
            {ZPOOL_CONFIG_VDEV_IND_SCRUB_HISTO,    "scrub_read_ind"},
            {ZPOOL_CONFIG_VDEV_SYNC_AGG_R_HISTO,   "sync_read_agg"},
            {ZPOOL_CONFIG_VDEV_SYNC_AGG_W_HISTO,   "sync_write_agg"},
            {ZPOOL_CONFIG_VDEV_ASYNC_AGG_R_HISTO,  "async_read_agg"},
            {ZPOOL_CONFIG_VDEV_ASYNC_AGG_W_HISTO,  "async_write_agg"},
            {ZPOOL_CONFIG_VDEV_AGG_SCRUB_HISTO,    "scrub_read_agg"},
#ifdef ZPOOL_CONFIG_VDEV_IND_TRIM_HISTO
            {ZPOOL_CONFIG_VDEV_IND_TRIM_HISTO,    "trim_write_ind"},
            {ZPOOL_CONFIG_VDEV_AGG_TRIM_HISTO,    "trim_write_agg"},
#endif
            {ZPOOL_CONFIG_VDEV_IND_REBUILD_HISTO,    "rebuild_write_ind"},
            {ZPOOL_CONFIG_VDEV_AGG_REBUILD_HISTO,    "rebuild_write_agg"},
            {NULL,      NULL}
        };

        if (nvlist_lookup_nvlist(nvroot,
            ZPOOL_CONFIG_VDEV_STATS_EX, &nv_ex) != 0) {
                return (6);
        }

        vdev_desc = get_vdev_desc(nvroot, parent_name);

        for (int i = 0; size_type[i].name; i++) {
                if (nvlist_lookup_uint64_array(nv_ex, size_type[i].name,
                    &size_type[i].array, &c) != 0) {
                        fprintf(stderr, "error: can't get %s\n",
                            size_type[i].name);
                        return (3);
                }
                /* end count count, all of the arrays are the same size */
                end = c - 1;
        }

        for (int bucket = 0; bucket <= end; bucket++) {
                if (bucket < MIN_SIZE_INDEX) {
                        /* don't print, but collect the sum */
                        for (int i = 0; size_type[i].name; i++) {
                                size_type[i].sum += size_type[i].array[bucket];
                        }
                        continue;
                }

                if (bucket < end) {
                        printf("%s%s,le=%llu,name=%s,%s ",
                            POOL_IO_SIZE_MEASUREMENT, tags, 1ULL << bucket,
                            pool_name, vdev_desc);
                } else {
                        printf("%s%s,le=+Inf,name=%s,%s ",
                            POOL_IO_SIZE_MEASUREMENT, tags, pool_name,
                            vdev_desc);
                }
                for (int i = 0; size_type[i].name; i++) {
                        if (bucket <= MIN_SIZE_INDEX || sum_histogram_buckets) {
                                size_type[i].sum += size_type[i].array[bucket];
                        } else {
                                size_type[i].sum = size_type[i].array[bucket];
                        }
                        print_kv(size_type[i].short_name, size_type[i].sum);
                        if (size_type[i + 1].name != NULL) {
                                printf(",");
                        }
                }
                printf(" %llu\n", (u_longlong_t)timestamp);
        }
        return (0);
}

/*
 * ZIO scheduler queue stats are stored as gauges. This is unfortunate
 * because the values can change very rapidly and any point-in-time
 * value will quickly be obsoleted. It is also not easy to downsample.
 * Thus only the top-level queue stats might be beneficial... maybe.
 */
static int
print_queue_stats(nvlist_t *nvroot, const char *pool_name,
    const char *parent_name)
{
        nvlist_t *nv_ex;
        uint64_t value;

        /* short_names are used for the field name */
        struct queue_lookup {
            const char *name;
            const char *short_name;
        };
        struct queue_lookup queue_type[] = {
            {ZPOOL_CONFIG_VDEV_SYNC_R_ACTIVE_QUEUE,     "sync_r_active"},
            {ZPOOL_CONFIG_VDEV_SYNC_W_ACTIVE_QUEUE,     "sync_w_active"},
            {ZPOOL_CONFIG_VDEV_ASYNC_R_ACTIVE_QUEUE,    "async_r_active"},
            {ZPOOL_CONFIG_VDEV_ASYNC_W_ACTIVE_QUEUE,    "async_w_active"},
            {ZPOOL_CONFIG_VDEV_SCRUB_ACTIVE_QUEUE,      "async_scrub_active"},
            {ZPOOL_CONFIG_VDEV_REBUILD_ACTIVE_QUEUE,    "rebuild_active"},
            {ZPOOL_CONFIG_VDEV_SYNC_R_PEND_QUEUE,       "sync_r_pend"},
            {ZPOOL_CONFIG_VDEV_SYNC_W_PEND_QUEUE,       "sync_w_pend"},
            {ZPOOL_CONFIG_VDEV_ASYNC_R_PEND_QUEUE,      "async_r_pend"},
            {ZPOOL_CONFIG_VDEV_ASYNC_W_PEND_QUEUE,      "async_w_pend"},
            {ZPOOL_CONFIG_VDEV_SCRUB_PEND_QUEUE,        "async_scrub_pend"},
            {ZPOOL_CONFIG_VDEV_REBUILD_PEND_QUEUE,      "rebuild_pend"},
            {NULL,      NULL}
        };

        if (nvlist_lookup_nvlist(nvroot,
            ZPOOL_CONFIG_VDEV_STATS_EX, &nv_ex) != 0) {
                return (6);
        }

        printf("%s%s,name=%s,%s ", POOL_QUEUE_MEASUREMENT, tags, pool_name,
            get_vdev_desc(nvroot, parent_name));
        for (int i = 0; queue_type[i].name; i++) {
                if (nvlist_lookup_uint64(nv_ex,
                    queue_type[i].name, &value) != 0) {
                        fprintf(stderr, "error: can't get %s\n",
                            queue_type[i].name);
                        return (3);
                }
                print_kv(queue_type[i].short_name, value);
                if (queue_type[i + 1].name != NULL) {
                        printf(",");
                }
        }
        printf(" %llu\n", (u_longlong_t)timestamp);
        return (0);
}

/*
 * top-level vdev stats are at the pool level
 */
static int
print_top_level_vdev_stats(nvlist_t *nvroot, const char *pool_name)
{
        nvlist_t *nv_ex;
        uint64_t value;

        /* short_names become part of the metric name */
        struct queue_lookup {
            const char *name;
            const char *short_name;
        };
        struct queue_lookup queue_type[] = {
            {ZPOOL_CONFIG_VDEV_SYNC_R_ACTIVE_QUEUE, "sync_r_active_queue"},
            {ZPOOL_CONFIG_VDEV_SYNC_W_ACTIVE_QUEUE, "sync_w_active_queue"},
            {ZPOOL_CONFIG_VDEV_ASYNC_R_ACTIVE_QUEUE, "async_r_active_queue"},
            {ZPOOL_CONFIG_VDEV_ASYNC_W_ACTIVE_QUEUE, "async_w_active_queue"},
            {ZPOOL_CONFIG_VDEV_SCRUB_ACTIVE_QUEUE, "async_scrub_active_queue"},
            {ZPOOL_CONFIG_VDEV_REBUILD_ACTIVE_QUEUE, "rebuild_active_queue"},
            {ZPOOL_CONFIG_VDEV_SYNC_R_PEND_QUEUE, "sync_r_pend_queue"},
            {ZPOOL_CONFIG_VDEV_SYNC_W_PEND_QUEUE, "sync_w_pend_queue"},
            {ZPOOL_CONFIG_VDEV_ASYNC_R_PEND_QUEUE, "async_r_pend_queue"},
            {ZPOOL_CONFIG_VDEV_ASYNC_W_PEND_QUEUE, "async_w_pend_queue"},
            {ZPOOL_CONFIG_VDEV_SCRUB_PEND_QUEUE, "async_scrub_pend_queue"},
            {ZPOOL_CONFIG_VDEV_REBUILD_PEND_QUEUE, "rebuild_pend_queue"},
            {NULL, NULL}
        };

        if (nvlist_lookup_nvlist(nvroot,
            ZPOOL_CONFIG_VDEV_STATS_EX, &nv_ex) != 0) {
                return (6);
        }

        printf("%s%s,name=%s,vdev=root ", VDEV_MEASUREMENT, tags,
            pool_name);
        for (int i = 0; queue_type[i].name; i++) {
                if (nvlist_lookup_uint64(nv_ex,
                    queue_type[i].name, &value) != 0) {
                        fprintf(stderr, "error: can't get %s\n",
                            queue_type[i].name);
                        return (3);
                }
                if (i > 0)
                        printf(",");
                print_kv(queue_type[i].short_name, value);
        }

        printf(" %llu\n", (u_longlong_t)timestamp);
        return (0);
}

/*
 * recursive stats printer
 */
static int
print_recursive_stats(stat_printer_f func, nvlist_t *nvroot,
    const char *pool_name, const char *parent_name, int descend)
{
        uint_t c, children;
        nvlist_t **child;
        char vdev_name[256];
        int err;

        err = func(nvroot, pool_name, parent_name);
        if (err)
                return (err);

        if (descend && nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_CHILDREN,
            &child, &children) == 0) {
                (void) strlcpy(vdev_name, get_vdev_name(nvroot, parent_name),
                    sizeof (vdev_name));

                for (c = 0; c < children; c++) {
                        err = print_recursive_stats(func, child[c], pool_name,
                            vdev_name, descend);
                        if (err)
                                return (err);
                }
        }
        return (0);
}

/*
 * call-back to print the stats from the pool config
 *
 * Note: if the pool is broken, this can hang indefinitely and perhaps in an
 * unkillable state.
 */
static int
print_stats(zpool_handle_t *zhp, void *data)
{
        uint_t c;
        int err;
        boolean_t missing;
        nvlist_t *config, *nvroot;
        vdev_stat_t *vs;
        struct timespec tv;
        char *pool_name;

        /* if not this pool return quickly */
        if (data &&
            strncmp(data, zpool_get_name(zhp), ZFS_MAX_DATASET_NAME_LEN) != 0) {
                zpool_close(zhp);
                return (0);
        }

        if (zpool_refresh_stats(zhp, &missing) != 0) {
                zpool_close(zhp);
                return (1);
        }

        config = zpool_get_config(zhp, NULL);
        if (clock_gettime(CLOCK_REALTIME, &tv) != 0)
                timestamp = (uint64_t)time(NULL) * 1000000000;
        else
                timestamp =
                    ((uint64_t)tv.tv_sec * 1000000000) + (uint64_t)tv.tv_nsec;

        if (nvlist_lookup_nvlist(
            config, ZPOOL_CONFIG_VDEV_TREE, &nvroot) != 0) {
        zpool_close(zhp);
                return (2);
        }
        if (nvlist_lookup_uint64_array(nvroot, ZPOOL_CONFIG_VDEV_STATS,
            (uint64_t **)&vs, &c) != 0) {
        zpool_close(zhp);
                return (3);
        }

        pool_name = escape_string(zpool_get_name(zhp));
        err = print_recursive_stats(print_summary_stats, nvroot,
            pool_name, NULL, 1);
        /* if any of these return an error, skip the rest */
        if (err == 0)
        err = print_top_level_vdev_stats(nvroot, pool_name);

        if (no_histograms == 0) {
        if (err == 0)
                err = print_recursive_stats(print_vdev_latency_stats, nvroot,
                    pool_name, NULL, 1);
        if (err == 0)
                err = print_recursive_stats(print_vdev_size_stats, nvroot,
                    pool_name, NULL, 1);
        if (err == 0)
                err = print_recursive_stats(print_queue_stats, nvroot,
                    pool_name, NULL, 0);
        }
        if (err == 0)
                err = print_scan_status(nvroot, pool_name);

        free(pool_name);
        zpool_close(zhp);
        return (err);
}

static void
usage(char *name)
{
        fprintf(stderr, "usage: %s [--execd][--no-histograms]"
            "[--sum-histogram-buckets] [--signed-int] [poolname]\n", name);
        exit(EXIT_FAILURE);
}

int
main(int argc, char *argv[])
{
        int opt;
        int ret = 8;
        char *line = NULL, *ttags = NULL;
        size_t len, tagslen = 0;
        struct option long_options[] = {
            {"execd", no_argument, NULL, 'e'},
            {"help", no_argument, NULL, 'h'},
            {"no-histograms", no_argument, NULL, 'n'},
            {"signed-int", no_argument, NULL, 'i'},
            {"sum-histogram-buckets", no_argument, NULL, 's'},
            {"tags", required_argument, NULL, 't'},
            {0, 0, 0, 0}
        };
        while ((opt = getopt_long(
            argc, argv, "ehinst:", long_options, NULL)) != -1) {
                switch (opt) {
                case 'e':
                        execd_mode = 1;
                        break;
                case 'i':
                        metric_data_type = 'i';
                        metric_value_mask = INT64_MAX;
                        break;
                case 'n':
                        no_histograms = 1;
                        break;
                case 's':
                        sum_histogram_buckets = 1;
                        break;
                case 't':
                        free(ttags);
                        tagslen = strlen(optarg) + 2;
                        ttags = calloc(1, tagslen);
                        if (ttags == NULL) {
                                fprintf(stderr,
                                    "error: cannot allocate memory "
                                    "for tags\n");
                                exit(1);
                        }
                        (void) snprintf(ttags, tagslen, ",%s", optarg);
                        tags = ttags;
                        break;
                default:
                        usage(argv[0]);
                }
        }

        libzfs_handle_t *g_zfs;
        if ((g_zfs = libzfs_init()) == NULL) {
                fprintf(stderr,
                    "error: cannot initialize libzfs. "
                    "Is the zfs module loaded or zrepl running?\n");
                exit(EXIT_FAILURE);
        }
        if (execd_mode == 0) {
                ret = zpool_iter(g_zfs, print_stats, argv[optind]);
                return (ret);
        }
        while (getline(&line, &len, stdin) != -1) {
                ret = zpool_iter(g_zfs, print_stats, argv[optind]);
                fflush(stdout);
        }
        return (ret);
}