FreeBSD: Lock vnode in zfs_ioctl()

[zfs.git] / module / zfs / spa_config.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 https://opensource.org/licenses/CDDL-1.0.
 * 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.
 * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
 * Copyright (c) 2011, 2020 by Delphix. All rights reserved.
 * Copyright 2017 Joyent, Inc.
 * Copyright (c) 2021, Colm Buckley <colm@tuatha.org>
 */

#include <sys/spa.h>
#include <sys/file.h>
#include <sys/fm/fs/zfs.h>
#include <sys/spa_impl.h>
#include <sys/nvpair.h>
#include <sys/fs/zfs.h>
#include <sys/vdev_impl.h>
#include <sys/zfs_ioctl.h>
#include <sys/systeminfo.h>
#include <sys/sunddi.h>
#include <sys/zfeature.h>
#include <sys/zfs_file.h>
#include <sys/zfs_context.h>
#ifdef _KERNEL
#include <sys/zone.h>
#endif

/*
 * Pool configuration repository.
 *
 * Pool configuration is stored as a packed nvlist on the filesystem.  By
 * default, all pools are stored in /etc/zfs/zpool.cache and loaded on boot
 * (when the ZFS module is loaded).  Pools can also have the 'cachefile'
 * property set that allows them to be stored in an alternate location until
 * the control of external software.
 *
 * For each cache file, we have a single nvlist which holds all the
 * configuration information.  When the module loads, we read this information
 * from /etc/zfs/zpool.cache and populate the SPA namespace.  This namespace is
 * maintained independently in spa.c.  Whenever the namespace is modified, or
 * the configuration of a pool is changed, we call spa_write_cachefile(), which
 * walks through all the active pools and writes the configuration to disk.
 */

static uint64_t spa_config_generation = 1;

/*
 * This can be overridden in userland to preserve an alternate namespace for
 * userland pools when doing testing.
 */
char *spa_config_path = (char *)ZPOOL_CACHE;
#ifdef _KERNEL
static int zfs_autoimport_disable = B_TRUE;
#endif

/*
 * Called when the module is first loaded, this routine loads the configuration
 * file into the SPA namespace.  It does not actually open or load the pools; it
 * only populates the namespace.
 */
void
spa_config_load(void)
{
        void *buf = NULL;
        nvlist_t *nvlist, *child;
        nvpair_t *nvpair;
        char *pathname;
        zfs_file_t *fp;
        zfs_file_attr_t zfa;
        uint64_t fsize;
        int err;

#ifdef _KERNEL
        if (zfs_autoimport_disable)
                return;
#endif

        /*
         * Open the configuration file.
         */
        pathname = kmem_alloc(MAXPATHLEN, KM_SLEEP);

        (void) snprintf(pathname, MAXPATHLEN, "%s", spa_config_path);

        err = zfs_file_open(pathname, O_RDONLY, 0, &fp);

#ifdef __FreeBSD__
        if (err)
                err = zfs_file_open(ZPOOL_CACHE_BOOT, O_RDONLY, 0, &fp);
#endif
        kmem_free(pathname, MAXPATHLEN);

        if (err)
                return;

        if (zfs_file_getattr(fp, &zfa))
                goto out;

        fsize = zfa.zfa_size;
        buf = kmem_alloc(fsize, KM_SLEEP);

        /*
         * Read the nvlist from the file.
         */
        if (zfs_file_read(fp, buf, fsize, NULL) < 0)
                goto out;

        /*
         * Unpack the nvlist.
         */
        if (nvlist_unpack(buf, fsize, &nvlist, KM_SLEEP) != 0)
                goto out;

        /*
         * Iterate over all elements in the nvlist, creating a new spa_t for
         * each one with the specified configuration.
         */
        mutex_enter(&spa_namespace_lock);
        nvpair = NULL;
        while ((nvpair = nvlist_next_nvpair(nvlist, nvpair)) != NULL) {
                if (nvpair_type(nvpair) != DATA_TYPE_NVLIST)
                        continue;

                child = fnvpair_value_nvlist(nvpair);

                if (spa_lookup(nvpair_name(nvpair)) != NULL)
                        continue;
                (void) spa_add(nvpair_name(nvpair), child, NULL);
        }
        mutex_exit(&spa_namespace_lock);

        nvlist_free(nvlist);

out:
        if (buf != NULL)
                kmem_free(buf, fsize);

        zfs_file_close(fp);
}

static int
spa_config_remove(spa_config_dirent_t *dp)
{
        int error = 0;

        /*
         * Remove the cache file.  If zfs_file_unlink() in not supported by the
         * platform fallback to truncating the file which is functionally
         * equivalent.
         */
        error = zfs_file_unlink(dp->scd_path);
        if (error == EOPNOTSUPP) {
                int flags = O_RDWR | O_TRUNC;
                zfs_file_t *fp;

                error = zfs_file_open(dp->scd_path, flags, 0644, &fp);
                if (error == 0) {
                        (void) zfs_file_fsync(fp, O_SYNC);
                        (void) zfs_file_close(fp);
                }
        }

        return (error);
}

static int
spa_config_write(spa_config_dirent_t *dp, nvlist_t *nvl)
{
        size_t buflen;
        char *buf;
        int oflags = O_RDWR | O_TRUNC | O_CREAT | O_LARGEFILE;
        char *temp;
        int err;
        zfs_file_t *fp;

        /*
         * If the nvlist is empty (NULL), then remove the old cachefile.
         */
        if (nvl == NULL) {
                err = spa_config_remove(dp);
                if (err == ENOENT)
                        err = 0;

                return (err);
        }

        /*
         * Pack the configuration into a buffer.
         */
        buf = fnvlist_pack(nvl, &buflen);
        temp = kmem_zalloc(MAXPATHLEN, KM_SLEEP);

        /*
         * Write the configuration to disk.  Due to the complexity involved
         * in performing a rename and remove from within the kernel the file
         * is instead truncated and overwritten in place.  This way we always
         * have a consistent view of the data or a zero length file.
         */
        err = zfs_file_open(dp->scd_path, oflags, 0644, &fp);
        if (err == 0) {
                err = zfs_file_write(fp, buf, buflen, NULL);
                if (err == 0)
                        err = zfs_file_fsync(fp, O_SYNC);

                zfs_file_close(fp);
                if (err)
                        (void) spa_config_remove(dp);
        }
        fnvlist_pack_free(buf, buflen);
        kmem_free(temp, MAXPATHLEN);
        return (err);
}

/*
 * Synchronize pool configuration to disk.  This must be called with the
 * namespace lock held. Synchronizing the pool cache is typically done after
 * the configuration has been synced to the MOS. This exposes a window where
 * the MOS config will have been updated but the cache file has not. If
 * the system were to crash at that instant then the cached config may not
 * contain the correct information to open the pool and an explicit import
 * would be required.
 */
void
spa_write_cachefile(spa_t *target, boolean_t removing, boolean_t postsysevent,
    boolean_t postblkidevent)
{
        spa_config_dirent_t *dp, *tdp;
        nvlist_t *nvl;
        const char *pool_name;
        boolean_t ccw_failure;
        int error = 0;

        ASSERT(MUTEX_HELD(&spa_namespace_lock));

        if (!(spa_mode_global & SPA_MODE_WRITE))
                return;

        /*
         * Iterate over all cachefiles for the pool, past or present.  When the
         * cachefile is changed, the new one is pushed onto this list, allowing
         * us to update previous cachefiles that no longer contain this pool.
         */
        ccw_failure = B_FALSE;
        for (dp = list_head(&target->spa_config_list); dp != NULL;
            dp = list_next(&target->spa_config_list, dp)) {
                spa_t *spa = NULL;
                if (dp->scd_path == NULL)
                        continue;

                /*
                 * Iterate over all pools, adding any matching pools to 'nvl'.
                 */
                nvl = NULL;
                while ((spa = spa_next(spa)) != NULL) {
                        /*
                         * Skip over our own pool if we're about to remove
                         * ourselves from the spa namespace or any pool that
                         * is readonly. Since we cannot guarantee that a
                         * readonly pool would successfully import upon reboot,
                         * we don't allow them to be written to the cache file.
                         */
                        if ((spa == target && removing) ||
                            !spa_writeable(spa))
                                continue;

                        mutex_enter(&spa->spa_props_lock);
                        tdp = list_head(&spa->spa_config_list);
                        if (spa->spa_config == NULL ||
                            tdp == NULL ||
                            tdp->scd_path == NULL ||
                            strcmp(tdp->scd_path, dp->scd_path) != 0) {
                                mutex_exit(&spa->spa_props_lock);
                                continue;
                        }

                        if (nvl == NULL)
                                nvl = fnvlist_alloc();

                        if (spa->spa_import_flags & ZFS_IMPORT_TEMP_NAME)
                                pool_name = fnvlist_lookup_string(
                                    spa->spa_config, ZPOOL_CONFIG_POOL_NAME);
                        else
                                pool_name = spa_name(spa);

                        fnvlist_add_nvlist(nvl, pool_name, spa->spa_config);
                        mutex_exit(&spa->spa_props_lock);
                }

                error = spa_config_write(dp, nvl);
                if (error != 0)
                        ccw_failure = B_TRUE;
                nvlist_free(nvl);
        }

        if (ccw_failure) {
                /*
                 * Keep trying so that configuration data is
                 * written if/when any temporary filesystem
                 * resource issues are resolved.
                 */
                if (target->spa_ccw_fail_time == 0) {
                        (void) zfs_ereport_post(
                            FM_EREPORT_ZFS_CONFIG_CACHE_WRITE,
                            target, NULL, NULL, NULL, 0);
                }
                target->spa_ccw_fail_time = gethrtime();
                spa_async_request(target, SPA_ASYNC_CONFIG_UPDATE);
        } else {
                /*
                 * Do not rate limit future attempts to update
                 * the config cache.
                 */
                target->spa_ccw_fail_time = 0;
        }

        /*
         * Remove any config entries older than the current one.
         */
        dp = list_head(&target->spa_config_list);
        while ((tdp = list_next(&target->spa_config_list, dp)) != NULL) {
                list_remove(&target->spa_config_list, tdp);
                if (tdp->scd_path != NULL)
                        spa_strfree(tdp->scd_path);
                kmem_free(tdp, sizeof (spa_config_dirent_t));
        }

        spa_config_generation++;

        if (postsysevent)
                spa_event_notify(target, NULL, NULL, ESC_ZFS_CONFIG_SYNC);

        /*
         * Post udev event to sync blkid information if the pool is created
         * or a new vdev is added to the pool.
         */
        if ((target->spa_root_vdev) && postblkidevent) {
                vdev_post_kobj_evt(target->spa_root_vdev);
                for (int i = 0; i < target->spa_l2cache.sav_count; i++)
                        vdev_post_kobj_evt(target->spa_l2cache.sav_vdevs[i]);
                for (int i = 0; i < target->spa_spares.sav_count; i++)
                        vdev_post_kobj_evt(target->spa_spares.sav_vdevs[i]);
        }
}

/*
 * Sigh.  Inside a local zone, we don't have access to /etc/zfs/zpool.cache,
 * and we don't want to allow the local zone to see all the pools anyway.
 * So we have to invent the ZFS_IOC_CONFIG ioctl to grab the configuration
 * information for all pool visible within the zone.
 */
int
spa_all_configs(uint64_t *generation, nvlist_t **pools)
{
        spa_t *spa = NULL;

        if (*generation == spa_config_generation)
                return (SET_ERROR(EEXIST));

        int error = mutex_enter_interruptible(&spa_namespace_lock);
        if (error)
                return (SET_ERROR(EINTR));

        *pools = fnvlist_alloc();
        while ((spa = spa_next(spa)) != NULL) {
                if (INGLOBALZONE(curproc) ||
                    zone_dataset_visible(spa_name(spa), NULL)) {
                        mutex_enter(&spa->spa_props_lock);
                        fnvlist_add_nvlist(*pools, spa_name(spa),
                            spa->spa_config);
                        mutex_exit(&spa->spa_props_lock);
                }
        }
        *generation = spa_config_generation;
        mutex_exit(&spa_namespace_lock);

        return (0);
}

void
spa_config_set(spa_t *spa, nvlist_t *config)
{
        mutex_enter(&spa->spa_props_lock);
        if (spa->spa_config != NULL && spa->spa_config != config)
                nvlist_free(spa->spa_config);
        spa->spa_config = config;
        mutex_exit(&spa->spa_props_lock);
}

/*
 * Generate the pool's configuration based on the current in-core state.
 *
 * We infer whether to generate a complete config or just one top-level config
 * based on whether vd is the root vdev.
 */
nvlist_t *
spa_config_generate(spa_t *spa, vdev_t *vd, uint64_t txg, int getstats)
{
        nvlist_t *config, *nvroot;
        vdev_t *rvd = spa->spa_root_vdev;
        unsigned long hostid = 0;
        boolean_t locked = B_FALSE;
        uint64_t split_guid;
        const char *pool_name;

        if (vd == NULL) {
                vd = rvd;
                locked = B_TRUE;
                spa_config_enter(spa, SCL_CONFIG | SCL_STATE, FTAG, RW_READER);
        }

        ASSERT(spa_config_held(spa, SCL_CONFIG | SCL_STATE, RW_READER) ==
            (SCL_CONFIG | SCL_STATE));

        /*
         * If txg is -1, report the current value of spa->spa_config_txg.
         */
        if (txg == -1ULL)
                txg = spa->spa_config_txg;

        /*
         * Originally, users had to handle spa namespace collisions by either
         * exporting the already imported pool or by specifying a new name for
         * the pool with a conflicting name. In the case of root pools from
         * virtual guests, neither approach to collision resolution is
         * reasonable. This is addressed by extending the new name syntax with
         * an option to specify that the new name is temporary. When specified,
         * ZFS_IMPORT_TEMP_NAME will be set in spa->spa_import_flags to tell us
         * to use the previous name, which we do below.
         */
        if (spa->spa_import_flags & ZFS_IMPORT_TEMP_NAME) {
                VERIFY0(nvlist_lookup_string(spa->spa_config,
                    ZPOOL_CONFIG_POOL_NAME, &pool_name));
        } else
                pool_name = spa_name(spa);

        config = fnvlist_alloc();

        fnvlist_add_uint64(config, ZPOOL_CONFIG_VERSION, spa_version(spa));
        fnvlist_add_string(config, ZPOOL_CONFIG_POOL_NAME, pool_name);
        fnvlist_add_uint64(config, ZPOOL_CONFIG_POOL_STATE, spa_state(spa));
        fnvlist_add_uint64(config, ZPOOL_CONFIG_POOL_TXG, txg);
        fnvlist_add_uint64(config, ZPOOL_CONFIG_POOL_GUID, spa_guid(spa));
        fnvlist_add_uint64(config, ZPOOL_CONFIG_ERRATA, spa->spa_errata);
        if (spa->spa_comment != NULL)
                fnvlist_add_string(config, ZPOOL_CONFIG_COMMENT,
                    spa->spa_comment);
        if (spa->spa_compatibility != NULL)
                fnvlist_add_string(config, ZPOOL_CONFIG_COMPATIBILITY,
                    spa->spa_compatibility);

        hostid = spa_get_hostid(spa);
        if (hostid != 0)
                fnvlist_add_uint64(config, ZPOOL_CONFIG_HOSTID, hostid);
        fnvlist_add_string(config, ZPOOL_CONFIG_HOSTNAME, utsname()->nodename);

        int config_gen_flags = 0;
        if (vd != rvd) {
                fnvlist_add_uint64(config, ZPOOL_CONFIG_TOP_GUID,
                    vd->vdev_top->vdev_guid);
                fnvlist_add_uint64(config, ZPOOL_CONFIG_GUID,
                    vd->vdev_guid);
                if (vd->vdev_isspare)
                        fnvlist_add_uint64(config,
                            ZPOOL_CONFIG_IS_SPARE, 1ULL);
                if (vd->vdev_islog)
                        fnvlist_add_uint64(config,
                            ZPOOL_CONFIG_IS_LOG, 1ULL);
                vd = vd->vdev_top;              /* label contains top config */
        } else {
                /*
                 * Only add the (potentially large) split information
                 * in the mos config, and not in the vdev labels
                 */
                if (spa->spa_config_splitting != NULL)
                        fnvlist_add_nvlist(config, ZPOOL_CONFIG_SPLIT,
                            spa->spa_config_splitting);

                fnvlist_add_boolean(config, ZPOOL_CONFIG_HAS_PER_VDEV_ZAPS);

                config_gen_flags |= VDEV_CONFIG_MOS;
        }

        /*
         * Add the top-level config.  We even add this on pools which
         * don't support holes in the namespace.
         */
        vdev_top_config_generate(spa, config);

        /*
         * If we're splitting, record the original pool's guid.
         */
        if (spa->spa_config_splitting != NULL &&
            nvlist_lookup_uint64(spa->spa_config_splitting,
            ZPOOL_CONFIG_SPLIT_GUID, &split_guid) == 0) {
                fnvlist_add_uint64(config, ZPOOL_CONFIG_SPLIT_GUID, split_guid);
        }

        nvroot = vdev_config_generate(spa, vd, getstats, config_gen_flags);
        fnvlist_add_nvlist(config, ZPOOL_CONFIG_VDEV_TREE, nvroot);
        nvlist_free(nvroot);

        /*
         * Store what's necessary for reading the MOS in the label.
         */
        fnvlist_add_nvlist(config, ZPOOL_CONFIG_FEATURES_FOR_READ,
            spa->spa_label_features);

        if (getstats && spa_load_state(spa) == SPA_LOAD_NONE) {
                ddt_histogram_t *ddh;
                ddt_stat_t *dds;
                ddt_object_t *ddo;

                ddh = kmem_zalloc(sizeof (ddt_histogram_t), KM_SLEEP);
                ddt_get_dedup_histogram(spa, ddh);
                fnvlist_add_uint64_array(config,
                    ZPOOL_CONFIG_DDT_HISTOGRAM,
                    (uint64_t *)ddh, sizeof (*ddh) / sizeof (uint64_t));
                kmem_free(ddh, sizeof (ddt_histogram_t));

                ddo = kmem_zalloc(sizeof (ddt_object_t), KM_SLEEP);
                ddt_get_dedup_object_stats(spa, ddo);
                fnvlist_add_uint64_array(config,
                    ZPOOL_CONFIG_DDT_OBJ_STATS,
                    (uint64_t *)ddo, sizeof (*ddo) / sizeof (uint64_t));
                kmem_free(ddo, sizeof (ddt_object_t));

                dds = kmem_zalloc(sizeof (ddt_stat_t), KM_SLEEP);
                ddt_get_dedup_stats(spa, dds);
                fnvlist_add_uint64_array(config,
                    ZPOOL_CONFIG_DDT_STATS,
                    (uint64_t *)dds, sizeof (*dds) / sizeof (uint64_t));
                kmem_free(dds, sizeof (ddt_stat_t));
        }

        if (locked)
                spa_config_exit(spa, SCL_CONFIG | SCL_STATE, FTAG);

        return (config);
}

/*
 * Update all disk labels, generate a fresh config based on the current
 * in-core state, and sync the global config cache (do not sync the config
 * cache if this is a booting rootpool).
 */
void
spa_config_update(spa_t *spa, int what)
{
        vdev_t *rvd = spa->spa_root_vdev;
        uint64_t txg;
        int c;

        ASSERT(MUTEX_HELD(&spa_namespace_lock));

        spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
        txg = spa_last_synced_txg(spa) + 1;
        if (what == SPA_CONFIG_UPDATE_POOL) {
                vdev_config_dirty(rvd);
        } else {
                /*
                 * If we have top-level vdevs that were added but have
                 * not yet been prepared for allocation, do that now.
                 * (It's safe now because the config cache is up to date,
                 * so it will be able to translate the new DVAs.)
                 * See comments in spa_vdev_add() for full details.
                 */
                for (c = 0; c < rvd->vdev_children; c++) {
                        vdev_t *tvd = rvd->vdev_child[c];

                        /*
                         * Explicitly skip vdevs that are indirect or
                         * log vdevs that are being removed. The reason
                         * is that both of those can have vdev_ms_array
                         * set to 0 and we wouldn't want to change their
                         * metaslab size nor call vdev_expand() on them.
                         */
                        if (!vdev_is_concrete(tvd) ||
                            (tvd->vdev_islog && tvd->vdev_removing))
                                continue;

                        if (tvd->vdev_ms_array == 0)
                                vdev_metaslab_set_size(tvd);
                        vdev_expand(tvd, txg);
                }
        }
        spa_config_exit(spa, SCL_ALL, FTAG);

        /*
         * Wait for the mosconfig to be regenerated and synced.
         */
        txg_wait_synced(spa->spa_dsl_pool, txg);

        /*
         * Update the global config cache to reflect the new mosconfig.
         */
        if (!spa->spa_is_root) {
                spa_write_cachefile(spa, B_FALSE,
                    what != SPA_CONFIG_UPDATE_POOL,
                    what != SPA_CONFIG_UPDATE_POOL);
        }

        if (what == SPA_CONFIG_UPDATE_POOL)
                spa_config_update(spa, SPA_CONFIG_UPDATE_VDEVS);
}

EXPORT_SYMBOL(spa_config_load);
EXPORT_SYMBOL(spa_all_configs);
EXPORT_SYMBOL(spa_config_set);
EXPORT_SYMBOL(spa_config_generate);
EXPORT_SYMBOL(spa_config_update);

#ifdef __linux__
/* string sysctls require a char array on FreeBSD */
ZFS_MODULE_PARAM(zfs_spa, spa_, config_path, STRING, ZMOD_RD,
        "SPA config file (/etc/zfs/zpool.cache)");
#endif

ZFS_MODULE_PARAM(zfs, zfs_, autoimport_disable, INT, ZMOD_RW,
        "Disable pool import at module load");