Create releng/7.2 from stable/7 in preparation for 7.2-RELEASE.

[FreeBSD/releng/7.2.git] / sys / cddl / contrib / opensolaris / uts / common / fs / zfs / spa_misc.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 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I%     %E% SMI"

#include <sys/zfs_context.h>
#include <sys/spa_impl.h>
#include <sys/zio.h>
#include <sys/zio_checksum.h>
#include <sys/zio_compress.h>
#include <sys/dmu.h>
#include <sys/dmu_tx.h>
#include <sys/zap.h>
#include <sys/zil.h>
#include <sys/vdev_impl.h>
#include <sys/metaslab.h>
#include <sys/uberblock_impl.h>
#include <sys/txg.h>
#include <sys/avl.h>
#include <sys/unique.h>
#include <sys/dsl_pool.h>
#include <sys/dsl_dir.h>
#include <sys/dsl_prop.h>
#include <sys/fs/zfs.h>

/*
 * SPA locking
 *
 * There are four basic locks for managing spa_t structures:
 *
 * spa_namespace_lock (global mutex)
 *
 *      This lock must be acquired to do any of the following:
 *
 *              - Lookup a spa_t by name
 *              - Add or remove a spa_t from the namespace
 *              - Increase spa_refcount from non-zero
 *              - Check if spa_refcount is zero
 *              - Rename a spa_t
 *              - add/remove/attach/detach devices
 *              - Held for the duration of create/destroy/import/export
 *
 *      It does not need to handle recursion.  A create or destroy may
 *      reference objects (files or zvols) in other pools, but by
 *      definition they must have an existing reference, and will never need
 *      to lookup a spa_t by name.
 *
 * spa_refcount (per-spa refcount_t protected by mutex)
 *
 *      This reference count keep track of any active users of the spa_t.  The
 *      spa_t cannot be destroyed or freed while this is non-zero.  Internally,
 *      the refcount is never really 'zero' - opening a pool implicitly keeps
 *      some references in the DMU.  Internally we check against SPA_MINREF, but
 *      present the image of a zero/non-zero value to consumers.
 *
 * spa_config_lock (per-spa crazy rwlock)
 *
 *      This SPA special is a recursive rwlock, capable of being acquired from
 *      asynchronous threads.  It has protects the spa_t from config changes,
 *      and must be held in the following circumstances:
 *
 *              - RW_READER to perform I/O to the spa
 *              - RW_WRITER to change the vdev config
 *
 * spa_config_cache_lock (per-spa mutex)
 *
 *      This mutex prevents the spa_config nvlist from being updated.  No
 *      other locks are required to obtain this lock, although implicitly you
 *      must have the namespace lock or non-zero refcount to have any kind
 *      of spa_t pointer at all.
 *
 * The locking order is fairly straightforward:
 *
 *              spa_namespace_lock      ->      spa_refcount
 *
 *      The namespace lock must be acquired to increase the refcount from 0
 *      or to check if it is zero.
 *
 *              spa_refcount            ->      spa_config_lock
 *
 *      There must be at least one valid reference on the spa_t to acquire
 *      the config lock.
 *
 *              spa_namespace_lock      ->      spa_config_lock
 *
 *      The namespace lock must always be taken before the config lock.
 *
 *
 * The spa_namespace_lock and spa_config_cache_lock can be acquired directly and
 * are globally visible.
 *
 * The namespace is manipulated using the following functions, all which require
 * the spa_namespace_lock to be held.
 *
 *      spa_lookup()            Lookup a spa_t by name.
 *
 *      spa_add()               Create a new spa_t in the namespace.
 *
 *      spa_remove()            Remove a spa_t from the namespace.  This also
 *                              frees up any memory associated with the spa_t.
 *
 *      spa_next()              Returns the next spa_t in the system, or the
 *                              first if NULL is passed.
 *
 *      spa_evict_all()         Shutdown and remove all spa_t structures in
 *                              the system.
 *
 *      spa_guid_exists()       Determine whether a pool/device guid exists.
 *
 * The spa_refcount is manipulated using the following functions:
 *
 *      spa_open_ref()          Adds a reference to the given spa_t.  Must be
 *                              called with spa_namespace_lock held if the
 *                              refcount is currently zero.
 *
 *      spa_close()             Remove a reference from the spa_t.  This will
 *                              not free the spa_t or remove it from the
 *                              namespace.  No locking is required.
 *
 *      spa_refcount_zero()     Returns true if the refcount is currently
 *                              zero.  Must be called with spa_namespace_lock
 *                              held.
 *
 * The spa_config_lock is manipulated using the following functions:
 *
 *      spa_config_enter()      Acquire the config lock as RW_READER or
 *                              RW_WRITER.  At least one reference on the spa_t
 *                              must exist.
 *
 *      spa_config_exit()       Release the config lock.
 *
 *      spa_config_held()       Returns true if the config lock is currently
 *                              held in the given state.
 *
 * The vdev configuration is protected by spa_vdev_enter() / spa_vdev_exit().
 *
 *      spa_vdev_enter()        Acquire the namespace lock and the config lock
 *                              for writing.
 *
 *      spa_vdev_exit()         Release the config lock, wait for all I/O
 *                              to complete, sync the updated configs to the
 *                              cache, and release the namespace lock.
 *
 * The spa_name() function also requires either the spa_namespace_lock
 * or the spa_config_lock, as both are needed to do a rename.  spa_rename() is
 * also implemented within this file since is requires manipulation of the
 * namespace.
 */

static avl_tree_t spa_namespace_avl;
kmutex_t spa_namespace_lock;
static kcondvar_t spa_namespace_cv;
static int spa_active_count;
int spa_max_replication_override = SPA_DVAS_PER_BP;

static kmutex_t spa_spare_lock;
static avl_tree_t spa_spare_avl;

kmem_cache_t *spa_buffer_pool;
int spa_mode;

#ifdef ZFS_DEBUG
int zfs_flags = ~0;
#else
int zfs_flags = 0;
#endif

/*
 * zfs_recover can be set to nonzero to attempt to recover from
 * otherwise-fatal errors, typically caused by on-disk corruption.  When
 * set, calls to zfs_panic_recover() will turn into warning messages.
 */
int zfs_recover = 0;
SYSCTL_DECL(_vfs_zfs);
TUNABLE_INT("vfs.zfs.recover", &zfs_recover);
SYSCTL_INT(_vfs_zfs, OID_AUTO, recover, CTLFLAG_RDTUN, &zfs_recover, 0,
    "Try to recover from otherwise-fatal errors.");

#define SPA_MINREF      5       /* spa_refcnt for an open-but-idle pool */

/*
 * ==========================================================================
 * SPA namespace functions
 * ==========================================================================
 */

/*
 * Lookup the named spa_t in the AVL tree.  The spa_namespace_lock must be held.
 * Returns NULL if no matching spa_t is found.
 */
spa_t *
spa_lookup(const char *name)
{
        spa_t search, *spa;
        avl_index_t where;

        ASSERT(MUTEX_HELD(&spa_namespace_lock));

        search.spa_name = (char *)name;
        spa = avl_find(&spa_namespace_avl, &search, &where);

        return (spa);
}

/*
 * Create an uninitialized spa_t with the given name.  Requires
 * spa_namespace_lock.  The caller must ensure that the spa_t doesn't already
 * exist by calling spa_lookup() first.
 */
spa_t *
spa_add(const char *name, const char *altroot)
{
        spa_t *spa;

        ASSERT(MUTEX_HELD(&spa_namespace_lock));

        spa = kmem_zalloc(sizeof (spa_t), KM_SLEEP);

        spa->spa_name = spa_strdup(name);
        spa->spa_state = POOL_STATE_UNINITIALIZED;
        spa->spa_freeze_txg = UINT64_MAX;
        spa->spa_final_txg = UINT64_MAX;

        mutex_init(&spa->spa_config_cache_lock, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&spa->spa_async_lock, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&spa->spa_scrub_lock, NULL, MUTEX_DEFAULT, NULL);

        cv_init(&spa->spa_scrub_cv, NULL, CV_DEFAULT, NULL);
        cv_init(&spa->spa_scrub_io_cv, NULL, CV_DEFAULT, NULL);
        cv_init(&spa->spa_async_cv, NULL, CV_DEFAULT, NULL);

        refcount_create(&spa->spa_refcount);
        refcount_create(&spa->spa_config_lock.scl_count);

        avl_add(&spa_namespace_avl, spa);

        /*
         * Set the alternate root, if there is one.
         */
        if (altroot) {
                spa->spa_root = spa_strdup(altroot);
                spa_active_count++;
        }

        return (spa);
}

/*
 * Removes a spa_t from the namespace, freeing up any memory used.  Requires
 * spa_namespace_lock.  This is called only after the spa_t has been closed and
 * deactivated.
 */
void
spa_remove(spa_t *spa)
{
        ASSERT(MUTEX_HELD(&spa_namespace_lock));
        ASSERT(spa->spa_state == POOL_STATE_UNINITIALIZED);
        ASSERT(spa->spa_scrub_thread == NULL);

        avl_remove(&spa_namespace_avl, spa);
        cv_broadcast(&spa_namespace_cv);

        if (spa->spa_root) {
                spa_strfree(spa->spa_root);
                spa_active_count--;
        }

        if (spa->spa_name)
                spa_strfree(spa->spa_name);

        spa_config_set(spa, NULL);

        refcount_destroy(&spa->spa_refcount);
        refcount_destroy(&spa->spa_config_lock.scl_count);

        cv_destroy(&spa->spa_async_cv);
        cv_destroy(&spa->spa_scrub_io_cv);
        cv_destroy(&spa->spa_scrub_cv);

        mutex_destroy(&spa->spa_scrub_lock);
        mutex_destroy(&spa->spa_async_lock);
        mutex_destroy(&spa->spa_config_cache_lock);

        kmem_free(spa, sizeof (spa_t));
}

/*
 * Given a pool, return the next pool in the namespace, or NULL if there is
 * none.  If 'prev' is NULL, return the first pool.
 */
spa_t *
spa_next(spa_t *prev)
{
        ASSERT(MUTEX_HELD(&spa_namespace_lock));

        if (prev)
                return (AVL_NEXT(&spa_namespace_avl, prev));
        else
                return (avl_first(&spa_namespace_avl));
}

/*
 * ==========================================================================
 * SPA refcount functions
 * ==========================================================================
 */

/*
 * Add a reference to the given spa_t.  Must have at least one reference, or
 * have the namespace lock held.
 */
void
spa_open_ref(spa_t *spa, void *tag)
{
        ASSERT(refcount_count(&spa->spa_refcount) > SPA_MINREF ||
            MUTEX_HELD(&spa_namespace_lock));

        (void) refcount_add(&spa->spa_refcount, tag);
}

/*
 * Remove a reference to the given spa_t.  Must have at least one reference, or
 * have the namespace lock held.
 */
void
spa_close(spa_t *spa, void *tag)
{
        ASSERT(refcount_count(&spa->spa_refcount) > SPA_MINREF ||
            MUTEX_HELD(&spa_namespace_lock));

        (void) refcount_remove(&spa->spa_refcount, tag);
}

/*
 * Check to see if the spa refcount is zero.  Must be called with
 * spa_namespace_lock held.  We really compare against SPA_MINREF, which is the
 * number of references acquired when opening a pool
 */
boolean_t
spa_refcount_zero(spa_t *spa)
{
        ASSERT(MUTEX_HELD(&spa_namespace_lock));

        return (refcount_count(&spa->spa_refcount) == SPA_MINREF);
}

/*
 * ==========================================================================
 * SPA spare tracking
 * ==========================================================================
 */

/*
 * Spares are tracked globally due to the following constraints:
 *
 *      - A spare may be part of multiple pools.
 *      - A spare may be added to a pool even if it's actively in use within
 *        another pool.
 *      - A spare in use in any pool can only be the source of a replacement if
 *        the target is a spare in the same pool.
 *
 * We keep track of all spares on the system through the use of a reference
 * counted AVL tree.  When a vdev is added as a spare, or used as a replacement
 * spare, then we bump the reference count in the AVL tree.  In addition, we set
 * the 'vdev_isspare' member to indicate that the device is a spare (active or
 * inactive).  When a spare is made active (used to replace a device in the
 * pool), we also keep track of which pool its been made a part of.
 *
 * The 'spa_spare_lock' protects the AVL tree.  These functions are normally
 * called under the spa_namespace lock as part of vdev reconfiguration.  The
 * separate spare lock exists for the status query path, which does not need to
 * be completely consistent with respect to other vdev configuration changes.
 */

typedef struct spa_spare {
        uint64_t        spare_guid;
        uint64_t        spare_pool;
        avl_node_t      spare_avl;
        int             spare_count;
} spa_spare_t;

static int
spa_spare_compare(const void *a, const void *b)
{
        const spa_spare_t *sa = a;
        const spa_spare_t *sb = b;

        if (sa->spare_guid < sb->spare_guid)
                return (-1);
        else if (sa->spare_guid > sb->spare_guid)
                return (1);
        else
                return (0);
}

void
spa_spare_add(vdev_t *vd)
{
        avl_index_t where;
        spa_spare_t search;
        spa_spare_t *spare;

        mutex_enter(&spa_spare_lock);
        ASSERT(!vd->vdev_isspare);

        search.spare_guid = vd->vdev_guid;
        if ((spare = avl_find(&spa_spare_avl, &search, &where)) != NULL) {
                spare->spare_count++;
        } else {
                spare = kmem_zalloc(sizeof (spa_spare_t), KM_SLEEP);
                spare->spare_guid = vd->vdev_guid;
                spare->spare_count = 1;
                avl_insert(&spa_spare_avl, spare, where);
        }
        vd->vdev_isspare = B_TRUE;

        mutex_exit(&spa_spare_lock);
}

void
spa_spare_remove(vdev_t *vd)
{
        spa_spare_t search;
        spa_spare_t *spare;
        avl_index_t where;

        mutex_enter(&spa_spare_lock);

        search.spare_guid = vd->vdev_guid;
        spare = avl_find(&spa_spare_avl, &search, &where);

        ASSERT(vd->vdev_isspare);
        ASSERT(spare != NULL);

        if (--spare->spare_count == 0) {
                avl_remove(&spa_spare_avl, spare);
                kmem_free(spare, sizeof (spa_spare_t));
        } else if (spare->spare_pool == spa_guid(vd->vdev_spa)) {
                spare->spare_pool = 0ULL;
        }

        vd->vdev_isspare = B_FALSE;
        mutex_exit(&spa_spare_lock);
}

boolean_t
spa_spare_exists(uint64_t guid, uint64_t *pool)
{
        spa_spare_t search, *found;
        avl_index_t where;

        mutex_enter(&spa_spare_lock);

        search.spare_guid = guid;
        found = avl_find(&spa_spare_avl, &search, &where);

        if (pool) {
                if (found)
                        *pool = found->spare_pool;
                else
                        *pool = 0ULL;
        }

        mutex_exit(&spa_spare_lock);

        return (found != NULL);
}

void
spa_spare_activate(vdev_t *vd)
{
        spa_spare_t search, *found;
        avl_index_t where;

        mutex_enter(&spa_spare_lock);
        ASSERT(vd->vdev_isspare);

        search.spare_guid = vd->vdev_guid;
        found = avl_find(&spa_spare_avl, &search, &where);
        ASSERT(found != NULL);
        ASSERT(found->spare_pool == 0ULL);

        found->spare_pool = spa_guid(vd->vdev_spa);
        mutex_exit(&spa_spare_lock);
}

/*
 * ==========================================================================
 * SPA config locking
 * ==========================================================================
 */

/*
 * Acquire the config lock.  The config lock is a special rwlock that allows for
 * recursive enters.  Because these enters come from the same thread as well as
 * asynchronous threads working on behalf of the owner, we must unilaterally
 * allow all reads access as long at least one reader is held (even if a write
 * is requested).  This has the side effect of write starvation, but write locks
 * are extremely rare, and a solution to this problem would be significantly
 * more complex (if even possible).
 *
 * We would like to assert that the namespace lock isn't held, but this is a
 * valid use during create.
 */
void
spa_config_enter(spa_t *spa, krw_t rw, void *tag)
{
        spa_config_lock_t *scl = &spa->spa_config_lock;

        mutex_enter(&scl->scl_lock);

        if (scl->scl_writer != curthread) {
                if (rw == RW_READER) {
                        while (scl->scl_writer != NULL)
                                cv_wait(&scl->scl_cv, &scl->scl_lock);
                } else {
                        while (scl->scl_writer != NULL ||
                            !refcount_is_zero(&scl->scl_count))
                                cv_wait(&scl->scl_cv, &scl->scl_lock);
                        scl->scl_writer = curthread;
                }
        }

        (void) refcount_add(&scl->scl_count, tag);

        mutex_exit(&scl->scl_lock);
}

/*
 * Release the spa config lock, notifying any waiters in the process.
 */
void
spa_config_exit(spa_t *spa, void *tag)
{
        spa_config_lock_t *scl = &spa->spa_config_lock;

        mutex_enter(&scl->scl_lock);

        ASSERT(!refcount_is_zero(&scl->scl_count));
        if (refcount_remove(&scl->scl_count, tag) == 0) {
                cv_broadcast(&scl->scl_cv);
                scl->scl_writer = NULL;  /* OK in either case */
        }

        mutex_exit(&scl->scl_lock);
}

/*
 * Returns true if the config lock is held in the given manner.
 */
boolean_t
spa_config_held(spa_t *spa, krw_t rw)
{
        spa_config_lock_t *scl = &spa->spa_config_lock;
        boolean_t held;

        mutex_enter(&scl->scl_lock);
        if (rw == RW_WRITER)
                held = (scl->scl_writer == curthread);
        else
                held = !refcount_is_zero(&scl->scl_count);
        mutex_exit(&scl->scl_lock);

        return (held);
}

/*
 * ==========================================================================
 * SPA vdev locking
 * ==========================================================================
 */

/*
 * Lock the given spa_t for the purpose of adding or removing a vdev.
 * Grabs the global spa_namespace_lock plus the spa config lock for writing.
 * It returns the next transaction group for the spa_t.
 */
uint64_t
spa_vdev_enter(spa_t *spa)
{
        /*
         * Suspend scrub activity while we mess with the config.
         */
        spa_scrub_suspend(spa);

        mutex_enter(&spa_namespace_lock);

        spa_config_enter(spa, RW_WRITER, spa);

        return (spa_last_synced_txg(spa) + 1);
}

/*
 * Unlock the spa_t after adding or removing a vdev.  Besides undoing the
 * locking of spa_vdev_enter(), we also want make sure the transactions have
 * synced to disk, and then update the global configuration cache with the new
 * information.
 */
int
spa_vdev_exit(spa_t *spa, vdev_t *vd, uint64_t txg, int error)
{
        int config_changed = B_FALSE;

        ASSERT(txg > spa_last_synced_txg(spa));

        /*
         * Reassess the DTLs.
         */
        vdev_dtl_reassess(spa->spa_root_vdev, 0, 0, B_FALSE);

        /*
         * If the config changed, notify the scrub thread that it must restart.
         */
        if (error == 0 && !list_is_empty(&spa->spa_dirty_list)) {
                config_changed = B_TRUE;
                spa_scrub_restart(spa, txg);
        }

        spa_config_exit(spa, spa);

        /*
         * Allow scrubbing to resume.
         */
        spa_scrub_resume(spa);

        /*
         * Note: this txg_wait_synced() is important because it ensures
         * that there won't be more than one config change per txg.
         * This allows us to use the txg as the generation number.
         */
        if (error == 0)
                txg_wait_synced(spa->spa_dsl_pool, txg);

        if (vd != NULL) {
                ASSERT(!vd->vdev_detached || vd->vdev_dtl.smo_object == 0);
                vdev_free(vd);
        }

        /*
         * If the config changed, update the config cache.
         */
        if (config_changed)
                spa_config_sync();

        mutex_exit(&spa_namespace_lock);

        return (error);
}

/*
 * ==========================================================================
 * Miscellaneous functions
 * ==========================================================================
 */

/*
 * Rename a spa_t.
 */
int
spa_rename(const char *name, const char *newname)
{
        spa_t *spa;
        int err;

        /*
         * Lookup the spa_t and grab the config lock for writing.  We need to
         * actually open the pool so that we can sync out the necessary labels.
         * It's OK to call spa_open() with the namespace lock held because we
         * allow recursive calls for other reasons.
         */
        mutex_enter(&spa_namespace_lock);
        if ((err = spa_open(name, &spa, FTAG)) != 0) {
                mutex_exit(&spa_namespace_lock);
                return (err);
        }

        spa_config_enter(spa, RW_WRITER, FTAG);

        avl_remove(&spa_namespace_avl, spa);
        spa_strfree(spa->spa_name);
        spa->spa_name = spa_strdup(newname);
        avl_add(&spa_namespace_avl, spa);

        /*
         * Sync all labels to disk with the new names by marking the root vdev
         * dirty and waiting for it to sync.  It will pick up the new pool name
         * during the sync.
         */
        vdev_config_dirty(spa->spa_root_vdev);

        spa_config_exit(spa, FTAG);

        txg_wait_synced(spa->spa_dsl_pool, 0);

        /*
         * Sync the updated config cache.
         */
        spa_config_sync();

        spa_close(spa, FTAG);

        mutex_exit(&spa_namespace_lock);

        return (0);
}


/*
 * Determine whether a pool with given pool_guid exists.  If device_guid is
 * non-zero, determine whether the pool exists *and* contains a device with the
 * specified device_guid.
 */
boolean_t
spa_guid_exists(uint64_t pool_guid, uint64_t device_guid)
{
        spa_t *spa;
        avl_tree_t *t = &spa_namespace_avl;

        ASSERT(MUTEX_HELD(&spa_namespace_lock));

        for (spa = avl_first(t); spa != NULL; spa = AVL_NEXT(t, spa)) {
                if (spa->spa_state == POOL_STATE_UNINITIALIZED)
                        continue;
                if (spa->spa_root_vdev == NULL)
                        continue;
                if (spa_guid(spa) == pool_guid) {
                        if (device_guid == 0)
                                break;

                        if (vdev_lookup_by_guid(spa->spa_root_vdev,
                            device_guid) != NULL)
                                break;

                        /*
                         * Check any devices we may in the process of adding.
                         */
                        if (spa->spa_pending_vdev) {
                                if (vdev_lookup_by_guid(spa->spa_pending_vdev,
                                    device_guid) != NULL)
                                        break;
                        }
                }
        }

        return (spa != NULL);
}

char *
spa_strdup(const char *s)
{
        size_t len;
        char *new;

        len = strlen(s);
        new = kmem_alloc(len + 1, KM_SLEEP);
        bcopy(s, new, len);
        new[len] = '\0';

        return (new);
}

void
spa_strfree(char *s)
{
        kmem_free(s, strlen(s) + 1);
}

uint64_t
spa_get_random(uint64_t range)
{
        uint64_t r;

        ASSERT(range != 0);

        (void) random_get_pseudo_bytes((void *)&r, sizeof (uint64_t));

        return (r % range);
}

void
sprintf_blkptr(char *buf, int len, const blkptr_t *bp)
{
        int d;

        if (bp == NULL) {
                (void) snprintf(buf, len, "<NULL>");
                return;
        }

        if (BP_IS_HOLE(bp)) {
                (void) snprintf(buf, len, "<hole>");
                return;
        }

        (void) snprintf(buf, len, "[L%llu %s] %llxL/%llxP ",
            (u_longlong_t)BP_GET_LEVEL(bp),
            dmu_ot[BP_GET_TYPE(bp)].ot_name,
            (u_longlong_t)BP_GET_LSIZE(bp),
            (u_longlong_t)BP_GET_PSIZE(bp));

        for (d = 0; d < BP_GET_NDVAS(bp); d++) {
                const dva_t *dva = &bp->blk_dva[d];
                (void) snprintf(buf + strlen(buf), len - strlen(buf),
                    "DVA[%d]=<%llu:%llx:%llx> ", d,
                    (u_longlong_t)DVA_GET_VDEV(dva),
                    (u_longlong_t)DVA_GET_OFFSET(dva),
                    (u_longlong_t)DVA_GET_ASIZE(dva));
        }

        (void) snprintf(buf + strlen(buf), len - strlen(buf),
            "%s %s %s %s birth=%llu fill=%llu cksum=%llx:%llx:%llx:%llx",
            zio_checksum_table[BP_GET_CHECKSUM(bp)].ci_name,
            zio_compress_table[BP_GET_COMPRESS(bp)].ci_name,
            BP_GET_BYTEORDER(bp) == 0 ? "BE" : "LE",
            BP_IS_GANG(bp) ? "gang" : "contiguous",
            (u_longlong_t)bp->blk_birth,
            (u_longlong_t)bp->blk_fill,
            (u_longlong_t)bp->blk_cksum.zc_word[0],
            (u_longlong_t)bp->blk_cksum.zc_word[1],
            (u_longlong_t)bp->blk_cksum.zc_word[2],
            (u_longlong_t)bp->blk_cksum.zc_word[3]);
}

void
spa_freeze(spa_t *spa)
{
        uint64_t freeze_txg = 0;

        spa_config_enter(spa, RW_WRITER, FTAG);
        if (spa->spa_freeze_txg == UINT64_MAX) {
                freeze_txg = spa_last_synced_txg(spa) + TXG_SIZE;
                spa->spa_freeze_txg = freeze_txg;
        }
        spa_config_exit(spa, FTAG);
        if (freeze_txg != 0)
                txg_wait_synced(spa_get_dsl(spa), freeze_txg);
}

void
zfs_panic_recover(const char *fmt, ...)
{
        va_list adx;

        va_start(adx, fmt);
        vcmn_err(zfs_recover ? CE_WARN : CE_PANIC, fmt, adx);
        va_end(adx);
}

/*
 * ==========================================================================
 * Accessor functions
 * ==========================================================================
 */

krwlock_t *
spa_traverse_rwlock(spa_t *spa)
{
        return (&spa->spa_traverse_lock);
}

int
spa_traverse_wanted(spa_t *spa)
{
        return (spa->spa_traverse_wanted);
}

dsl_pool_t *
spa_get_dsl(spa_t *spa)
{
        return (spa->spa_dsl_pool);
}

blkptr_t *
spa_get_rootblkptr(spa_t *spa)
{
        return (&spa->spa_ubsync.ub_rootbp);
}

void
spa_set_rootblkptr(spa_t *spa, const blkptr_t *bp)
{
        spa->spa_uberblock.ub_rootbp = *bp;
}

void
spa_altroot(spa_t *spa, char *buf, size_t buflen)
{
        if (spa->spa_root == NULL)
                buf[0] = '\0';
        else
                (void) strncpy(buf, spa->spa_root, buflen);
}

int
spa_sync_pass(spa_t *spa)
{
        return (spa->spa_sync_pass);
}

char *
spa_name(spa_t *spa)
{
        /*
         * Accessing the name requires holding either the namespace lock or the
         * config lock, both of which are required to do a rename.
         */
        ASSERT(MUTEX_HELD(&spa_namespace_lock) ||
            spa_config_held(spa, RW_READER) || spa_config_held(spa, RW_WRITER));

        return (spa->spa_name);
}

uint64_t
spa_guid(spa_t *spa)
{
        /*
         * If we fail to parse the config during spa_load(), we can go through
         * the error path (which posts an ereport) and end up here with no root
         * vdev.  We stash the original pool guid in 'spa_load_guid' to handle
         * this case.
         */
        if (spa->spa_root_vdev != NULL)
                return (spa->spa_root_vdev->vdev_guid);
        else
                return (spa->spa_load_guid);
}

uint64_t
spa_last_synced_txg(spa_t *spa)
{
        return (spa->spa_ubsync.ub_txg);
}

uint64_t
spa_first_txg(spa_t *spa)
{
        return (spa->spa_first_txg);
}

int
spa_state(spa_t *spa)
{
        return (spa->spa_state);
}

uint64_t
spa_freeze_txg(spa_t *spa)
{
        return (spa->spa_freeze_txg);
}

/*
 * In the future, this may select among different metaslab classes
 * depending on the zdp.  For now, there's no such distinction.
 */
metaslab_class_t *
spa_metaslab_class_select(spa_t *spa)
{
        return (spa->spa_normal_class);
}

/*
 * Return how much space is allocated in the pool (ie. sum of all asize)
 */
uint64_t
spa_get_alloc(spa_t *spa)
{
        return (spa->spa_root_vdev->vdev_stat.vs_alloc);
}

/*
 * Return how much (raid-z inflated) space there is in the pool.
 */
uint64_t
spa_get_space(spa_t *spa)
{
        return (spa->spa_root_vdev->vdev_stat.vs_space);
}

/*
 * Return the amount of raid-z-deflated space in the pool.
 */
uint64_t
spa_get_dspace(spa_t *spa)
{
        if (spa->spa_deflate)
                return (spa->spa_root_vdev->vdev_stat.vs_dspace);
        else
                return (spa->spa_root_vdev->vdev_stat.vs_space);
}

/* ARGSUSED */
uint64_t
spa_get_asize(spa_t *spa, uint64_t lsize)
{
        /*
         * For now, the worst case is 512-byte RAID-Z blocks, in which
         * case the space requirement is exactly 2x; so just assume that.
         * Add to this the fact that we can have up to 3 DVAs per bp, and
         * we have to multiply by a total of 6x.
         */
        return (lsize * 6);
}

uint64_t
spa_version(spa_t *spa)
{
        return (spa->spa_ubsync.ub_version);
}

int
spa_max_replication(spa_t *spa)
{
        /*
         * As of ZFS_VERSION == ZFS_VERSION_DITTO_BLOCKS, we are able to
         * handle BPs with more than one DVA allocated.  Set our max
         * replication level accordingly.
         */
        if (spa_version(spa) < ZFS_VERSION_DITTO_BLOCKS)
                return (1);
        return (MIN(SPA_DVAS_PER_BP, spa_max_replication_override));
}

uint64_t
bp_get_dasize(spa_t *spa, const blkptr_t *bp)
{
        int sz = 0, i;

        if (!spa->spa_deflate)
                return (BP_GET_ASIZE(bp));

        for (i = 0; i < SPA_DVAS_PER_BP; i++) {
                vdev_t *vd =
                    vdev_lookup_top(spa, DVA_GET_VDEV(&bp->blk_dva[i]));
                sz += (DVA_GET_ASIZE(&bp->blk_dva[i]) >> SPA_MINBLOCKSHIFT) *
                    vd->vdev_deflate_ratio;
        }
        return (sz);
}

/*
 * ==========================================================================
 * Initialization and Termination
 * ==========================================================================
 */

static int
spa_name_compare(const void *a1, const void *a2)
{
        const spa_t *s1 = a1;
        const spa_t *s2 = a2;
        int s;

        s = strcmp(s1->spa_name, s2->spa_name);
        if (s > 0)
                return (1);
        if (s < 0)
                return (-1);
        return (0);
}

int
spa_busy(void)
{
        return (spa_active_count);
}

void
spa_init(int mode)
{
        mutex_init(&spa_namespace_lock, NULL, MUTEX_DEFAULT, NULL);
        cv_init(&spa_namespace_cv, NULL, CV_DEFAULT, NULL);

        avl_create(&spa_namespace_avl, spa_name_compare, sizeof (spa_t),
            offsetof(spa_t, spa_avl));

        mutex_init(&spa_spare_lock, NULL, MUTEX_DEFAULT, NULL);

        avl_create(&spa_spare_avl, spa_spare_compare, sizeof (spa_spare_t),
            offsetof(spa_spare_t, spare_avl));

        spa_mode = mode;

        refcount_sysinit();
        unique_init();
        zio_init();
        dmu_init();
        zil_init();
        spa_config_load();
}

void
spa_fini(void)
{
        spa_evict_all();

        zil_fini();
        dmu_fini();
        zio_fini();
        refcount_fini();

        avl_destroy(&spa_namespace_avl);
        avl_destroy(&spa_spare_avl);

        cv_destroy(&spa_namespace_cv);
        mutex_destroy(&spa_namespace_lock);
        mutex_destroy(&spa_spare_lock);
}