zfs/lib/libzfs/libzfs_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 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 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright (c) 2012 by Delphix. All rights reserved.
 */

/*
 * The pool configuration repository is stored in /etc/zfs/zpool.cache as a
 * single packed nvlist.  While it would be nice to just read in this
 * file from userland, this wouldn't work from a local zone.  So we have to have
 * a zpool ioctl to return the complete configuration for all pools.  In the
 * global zone, this will be identical to reading the file and unpacking it in
 * userland.
 */

#include <errno.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stddef.h>
#include <string.h>
#include <unistd.h>
#include <libintl.h>
#include <libuutil.h>

#include "libzfs_impl.h"

typedef struct config_node {
	char		*cn_name;
	nvlist_t	*cn_config;
	uu_avl_node_t	cn_avl;
} config_node_t;

/* ARGSUSED */
static int
config_node_compare(const void *a, const void *b, void *unused)
{
	int ret;

	const config_node_t *ca = (config_node_t *)a;
	const config_node_t *cb = (config_node_t *)b;

	ret = strcmp(ca->cn_name, cb->cn_name);

	if (ret < 0)
		return (-1);
	else if (ret > 0)
		return (1);
	else
		return (0);
}

void
namespace_clear(libzfs_handle_t *hdl)
{
	if (hdl->libzfs_ns_avl) {
		config_node_t *cn;
		void *cookie = NULL;

		while ((cn = uu_avl_teardown(hdl->libzfs_ns_avl,
		    &cookie)) != NULL) {
			nvlist_free(cn->cn_config);
			free(cn->cn_name);
			free(cn);
		}

		uu_avl_destroy(hdl->libzfs_ns_avl);
		hdl->libzfs_ns_avl = NULL;
	}

	if (hdl->libzfs_ns_avlpool) {
		uu_avl_pool_destroy(hdl->libzfs_ns_avlpool);
		hdl->libzfs_ns_avlpool = NULL;
	}
}

/*
 * Loads the pool namespace, or re-loads it if the cache has changed.
 */
static int
namespace_reload(libzfs_handle_t *hdl)
{
	nvlist_t *config;
	config_node_t *cn;
	nvpair_t *elem;
	zfs_cmd_t zc = {"\0", 0, 0, 0, 0, 0, 0, 0, "\0", "\0", "\0"};
	void *cookie;

	if (hdl->libzfs_ns_gen == 0) {
		/*
		 * This is the first time we've accessed the configuration
		 * cache.  Initialize the AVL tree and then fall through to the
		 * common code.
		 */
		if ((hdl->libzfs_ns_avlpool = uu_avl_pool_create("config_pool",
		    sizeof (config_node_t),
		    offsetof(config_node_t, cn_avl),
		    config_node_compare, UU_DEFAULT)) == NULL)
			return (no_memory(hdl));

		if ((hdl->libzfs_ns_avl = uu_avl_create(hdl->libzfs_ns_avlpool,
		    NULL, UU_DEFAULT)) == NULL)
			return (no_memory(hdl));
	}

	if (zcmd_alloc_dst_nvlist(hdl, &zc, 0) != 0)
		return (-1);

	for (;;) {
		zc.zc_cookie = hdl->libzfs_ns_gen;
		if (ioctl(hdl->libzfs_fd, ZFS_IOC_POOL_CONFIGS, &zc) != 0) {
			switch (errno) {
			case EEXIST:
				/*
				 * The namespace hasn't changed.
				 */
				zcmd_free_nvlists(&zc);
				return (0);

			case ENOMEM:
				if (zcmd_expand_dst_nvlist(hdl, &zc) != 0) {
					zcmd_free_nvlists(&zc);
					return (-1);
				}
				break;

			default:
				zcmd_free_nvlists(&zc);
				return (zfs_standard_error(hdl, errno,
				    dgettext(TEXT_DOMAIN, "failed to read "
				    "pool configuration")));
			}
		} else {
			hdl->libzfs_ns_gen = zc.zc_cookie;
			break;
		}
	}

	if (zcmd_read_dst_nvlist(hdl, &zc, &config) != 0) {
		zcmd_free_nvlists(&zc);
		return (-1);
	}

	zcmd_free_nvlists(&zc);

	/*
	 * Clear out any existing configuration information.
	 */
	cookie = NULL;
	while ((cn = uu_avl_teardown(hdl->libzfs_ns_avl, &cookie)) != NULL) {
		nvlist_free(cn->cn_config);
		free(cn->cn_name);
		free(cn);
	}

	elem = NULL;
	while ((elem = nvlist_next_nvpair(config, elem)) != NULL) {
		nvlist_t *child;
		uu_avl_index_t where;

		if ((cn = zfs_alloc(hdl, sizeof (config_node_t))) == NULL) {
			nvlist_free(config);
			return (-1);
		}

		if ((cn->cn_name = zfs_strdup(hdl,
		    nvpair_name(elem))) == NULL) {
			free(cn);
			nvlist_free(config);
			return (-1);
		}

		verify(nvpair_value_nvlist(elem, &child) == 0);
		if (nvlist_dup(child, &cn->cn_config, 0) != 0) {
			free(cn->cn_name);
			free(cn);
			nvlist_free(config);
			return (no_memory(hdl));
		}
		verify(uu_avl_find(hdl->libzfs_ns_avl, cn, NULL, &where)
		    == NULL);

		uu_avl_insert(hdl->libzfs_ns_avl, cn, where);
	}

	nvlist_free(config);
	return (0);
}

/*
 * Retrieve the configuration for the given pool.  The configuration is a nvlist
 * describing the vdevs, as well as the statistics associated with each one.
 */
nvlist_t *
zpool_get_config(zpool_handle_t *zhp, nvlist_t **oldconfig)
{
	if (oldconfig)
		*oldconfig = zhp->zpool_old_config;
	return (zhp->zpool_config);
}

/*
 * Retrieves a list of enabled features and their refcounts and caches it in
 * the pool handle.
 */
nvlist_t *
zpool_get_features(zpool_handle_t *zhp)
{
	nvlist_t *config, *features;

	config = zpool_get_config(zhp, NULL);

	if (config == NULL || !nvlist_exists(config,
	    ZPOOL_CONFIG_FEATURE_STATS)) {
		int error;
		boolean_t missing = B_FALSE;

		error = zpool_refresh_stats(zhp, &missing);

		if (error != 0 || missing)
			return (NULL);

		config = zpool_get_config(zhp, NULL);
	}

	verify(nvlist_lookup_nvlist(config, ZPOOL_CONFIG_FEATURE_STATS,
	    &features) == 0);

	return (features);
}

/*
 * Refresh the vdev statistics associated with the given pool.  This is used in
 * iostat to show configuration changes and determine the delta from the last
 * time the function was called.  This function can fail, in case the pool has
 * been destroyed.
 */
int
zpool_refresh_stats(zpool_handle_t *zhp, boolean_t *missing)
{
	zfs_cmd_t zc = {"\0", 0, 0, 0, 0, 0, 0, 0, "\0", "\0", "\0"};
	int error;
	nvlist_t *config;
	libzfs_handle_t *hdl = zhp->zpool_hdl;

	*missing = B_FALSE;
	(void) strcpy(zc.zc_name, zhp->zpool_name);

	if (zhp->zpool_config_size == 0)
		zhp->zpool_config_size = 1 << 16;

	if (zcmd_alloc_dst_nvlist(hdl, &zc, zhp->zpool_config_size) != 0)
		return (-1);

	for (;;) {
		if (ioctl(zhp->zpool_hdl->libzfs_fd, ZFS_IOC_POOL_STATS,
		    &zc) == 0) {
			/*
			 * The real error is returned in the zc_cookie field.
			 */
			error = zc.zc_cookie;
			break;
		}

		if (errno == ENOMEM) {
			if (zcmd_expand_dst_nvlist(hdl, &zc) != 0) {
				zcmd_free_nvlists(&zc);
				return (-1);
			}
		} else {
			zcmd_free_nvlists(&zc);
			if (errno == ENOENT || errno == EINVAL)
				*missing = B_TRUE;
			zhp->zpool_state = POOL_STATE_UNAVAIL;
			return (0);
		}
	}

	if (zcmd_read_dst_nvlist(hdl, &zc, &config) != 0) {
		zcmd_free_nvlists(&zc);
		return (-1);
	}

	zcmd_free_nvlists(&zc);

	zhp->zpool_config_size = zc.zc_nvlist_dst_size;

	if (zhp->zpool_config != NULL) {
		uint64_t oldtxg, newtxg;

		verify(nvlist_lookup_uint64(zhp->zpool_config,
		    ZPOOL_CONFIG_POOL_TXG, &oldtxg) == 0);
		verify(nvlist_lookup_uint64(config,
		    ZPOOL_CONFIG_POOL_TXG, &newtxg) == 0);

		if (zhp->zpool_old_config != NULL)
			nvlist_free(zhp->zpool_old_config);

		if (oldtxg != newtxg) {
			nvlist_free(zhp->zpool_config);
			zhp->zpool_old_config = NULL;
		} else {
			zhp->zpool_old_config = zhp->zpool_config;
		}
	}

	zhp->zpool_config = config;
	if (error)
		zhp->zpool_state = POOL_STATE_UNAVAIL;
	else
		zhp->zpool_state = POOL_STATE_ACTIVE;

	return (0);
}

/*
 * If the __ZFS_POOL_RESTRICT environment variable is set we only iterate over
 * pools it lists.
 *
 * This is an undocumented feature for use during testing only.
 *
 * This function returns B_TRUE if the pool should be skipped
 * during iteration.
 */
static boolean_t
check_restricted(const char *poolname)
{
	static boolean_t initialized = B_FALSE;
	static char *restricted = NULL;

	const char *cur, *end;
	int len, namelen;

	if (!initialized) {
		initialized = B_TRUE;
		restricted = getenv("__ZFS_POOL_RESTRICT");
	}

	if (NULL == restricted)
		return (B_FALSE);

	cur = restricted;
	namelen = strlen(poolname);
	do {
		end = strchr(cur, ' ');
		len = (NULL == end) ? strlen(cur) : (end - cur);

		if (len == namelen && 0 == strncmp(cur, poolname, len)) {
			return (B_FALSE);
		}

		cur += (len + 1);
	} while (NULL != end);

	return (B_TRUE);
}

/*
 * Iterate over all pools in the system.
 */
int
zpool_iter(libzfs_handle_t *hdl, zpool_iter_f func, void *data)
{
	config_node_t *cn;
	zpool_handle_t *zhp;
	int ret;

	/*
	 * If someone makes a recursive call to zpool_iter(), we want to avoid
	 * refreshing the namespace because that will invalidate the parent
	 * context.  We allow recursive calls, but simply re-use the same
	 * namespace AVL tree.
	 */
	if (!hdl->libzfs_pool_iter && namespace_reload(hdl) != 0)
		return (-1);

	hdl->libzfs_pool_iter++;
	for (cn = uu_avl_first(hdl->libzfs_ns_avl); cn != NULL;
	    cn = uu_avl_next(hdl->libzfs_ns_avl, cn)) {

		if (check_restricted(cn->cn_name))
			continue;

		if (zpool_open_silent(hdl, cn->cn_name, &zhp) != 0) {
			hdl->libzfs_pool_iter--;
			return (-1);
		}

		if (zhp == NULL)
			continue;

		if ((ret = func(zhp, data)) != 0) {
			hdl->libzfs_pool_iter--;
			return (ret);
		}
	}
	hdl->libzfs_pool_iter--;

	return (0);
}

/*
 * Iterate over root datasets, calling the given function for each.  The zfs
 * handle passed each time must be explicitly closed by the callback.
 */
int
zfs_iter_root(libzfs_handle_t *hdl, zfs_iter_f func, void *data)
{
	config_node_t *cn;
	zfs_handle_t *zhp;
	int ret;

	if (namespace_reload(hdl) != 0)
		return (-1);

	for (cn = uu_avl_first(hdl->libzfs_ns_avl); cn != NULL;
	    cn = uu_avl_next(hdl->libzfs_ns_avl, cn)) {

		if (check_restricted(cn->cn_name))
			continue;

		if ((zhp = make_dataset_handle(hdl, cn->cn_name)) == NULL)
			continue;

		if ((ret = func(zhp, data)) != 0)
			return (ret);
	}

	return (0);
}