Patrick Welche <prlw1@cam.ac.uk>

[netbsd-mini2440.git] / external / cddl / osnet / dist / uts / common / fs / zfs / spa_history.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 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

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

#include <sys/spa.h>
#include <sys/spa_impl.h>
#include <sys/zap.h>
#include <sys/dsl_synctask.h>
#include <sys/dmu_tx.h>
#include <sys/dmu_objset.h>
#include <sys/utsname.h>
#include <sys/cmn_err.h>
#include <sys/sunddi.h>
#ifdef _KERNEL
#include <sys/zone.h>
#endif

/*
 * Routines to manage the on-disk history log.
 *
 * The history log is stored as a dmu object containing
 * <packed record length, record nvlist> tuples.
 *
 * Where "record nvlist" is a nvlist containing uint64_ts and strings, and
 * "packed record length" is the packed length of the "record nvlist" stored
 * as a little endian uint64_t.
 *
 * The log is implemented as a ring buffer, though the original creation
 * of the pool ('zpool create') is never overwritten.
 *
 * The history log is tracked as object 'spa_t::spa_history'.  The bonus buffer
 * of 'spa_history' stores the offsets for logging/retrieving history as
 * 'spa_history_phys_t'.  'sh_pool_create_len' is the ending offset in bytes of
 * where the 'zpool create' record is stored.  This allows us to never
 * overwrite the original creation of the pool.  'sh_phys_max_off' is the
 * physical ending offset in bytes of the log.  This tells you the length of
 * the buffer. 'sh_eof' is the logical EOF (in bytes).  Whenever a record
 * is added, 'sh_eof' is incremented by the the size of the record.
 * 'sh_eof' is never decremented.  'sh_bof' is the logical BOF (in bytes).
 * This is where the consumer should start reading from after reading in
 * the 'zpool create' portion of the log.
 *
 * 'sh_records_lost' keeps track of how many records have been overwritten
 * and permanently lost.
 */

/* convert a logical offset to physical */
static uint64_t
spa_history_log_to_phys(uint64_t log_off, spa_history_phys_t *shpp)
{
        uint64_t phys_len;

        phys_len = shpp->sh_phys_max_off - shpp->sh_pool_create_len;
        return ((log_off - shpp->sh_pool_create_len) % phys_len
            + shpp->sh_pool_create_len);
}

void
spa_history_create_obj(spa_t *spa, dmu_tx_t *tx)
{
        dmu_buf_t *dbp;
        spa_history_phys_t *shpp;
        objset_t *mos = spa->spa_meta_objset;

        ASSERT(spa->spa_history == 0);
        spa->spa_history = dmu_object_alloc(mos, DMU_OT_SPA_HISTORY,
            SPA_MAXBLOCKSIZE, DMU_OT_SPA_HISTORY_OFFSETS,
            sizeof (spa_history_phys_t), tx);

        VERIFY(zap_add(mos, DMU_POOL_DIRECTORY_OBJECT,
            DMU_POOL_HISTORY, sizeof (uint64_t), 1,
            &spa->spa_history, tx) == 0);

        VERIFY(0 == dmu_bonus_hold(mos, spa->spa_history, FTAG, &dbp));
        ASSERT(dbp->db_size >= sizeof (spa_history_phys_t));

        shpp = dbp->db_data;
        dmu_buf_will_dirty(dbp, tx);

        /*
         * Figure out maximum size of history log.  We set it at
         * 1% of pool size, with a max of 32MB and min of 128KB.
         */
        shpp->sh_phys_max_off = spa_get_dspace(spa) / 100;
        shpp->sh_phys_max_off = MIN(shpp->sh_phys_max_off, 32<<20);
        shpp->sh_phys_max_off = MAX(shpp->sh_phys_max_off, 128<<10);

        dmu_buf_rele(dbp, FTAG);
}

/*
 * Change 'sh_bof' to the beginning of the next record.
 */
static int
spa_history_advance_bof(spa_t *spa, spa_history_phys_t *shpp)
{
        objset_t *mos = spa->spa_meta_objset;
        uint64_t firstread, reclen, phys_bof;
        char buf[sizeof (reclen)];
        int err;

        phys_bof = spa_history_log_to_phys(shpp->sh_bof, shpp);
        firstread = MIN(sizeof (reclen), shpp->sh_phys_max_off - phys_bof);

        if ((err = dmu_read(mos, spa->spa_history, phys_bof, firstread,
            buf)) != 0)
                return (err);
        if (firstread != sizeof (reclen)) {
                if ((err = dmu_read(mos, spa->spa_history,
                    shpp->sh_pool_create_len, sizeof (reclen) - firstread,
                    buf + firstread)) != 0)
                        return (err);
        }

        reclen = LE_64(*((uint64_t *)buf));
        shpp->sh_bof += reclen + sizeof (reclen);
        shpp->sh_records_lost++;
        return (0);
}

static int
spa_history_write(spa_t *spa, void *buf, uint64_t len, spa_history_phys_t *shpp,
    dmu_tx_t *tx)
{
        uint64_t firstwrite, phys_eof;
        objset_t *mos = spa->spa_meta_objset;
        int err;

        ASSERT(MUTEX_HELD(&spa->spa_history_lock));

        /* see if we need to reset logical BOF */
        while (shpp->sh_phys_max_off - shpp->sh_pool_create_len -
            (shpp->sh_eof - shpp->sh_bof) <= len) {
                if ((err = spa_history_advance_bof(spa, shpp)) != 0) {
                        return (err);
                }
        }

        phys_eof = spa_history_log_to_phys(shpp->sh_eof, shpp);
        firstwrite = MIN(len, shpp->sh_phys_max_off - phys_eof);
        shpp->sh_eof += len;
        dmu_write(mos, spa->spa_history, phys_eof, firstwrite, buf, tx);

        len -= firstwrite;
        if (len > 0) {
                /* write out the rest at the beginning of physical file */
                dmu_write(mos, spa->spa_history, shpp->sh_pool_create_len,
                    len, (char *)buf + firstwrite, tx);
        }

        return (0);
}

static char *
spa_history_zone()
{
#if defined(_KERNEL) && !defined(__NetBSD__)
        return (curproc->p_zone->zone_name);
#else
        return ("global");
#endif
}

/*
 * Write out a history event.
 */
static void
spa_history_log_sync(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
{
        spa_t           *spa = arg1;
        history_arg_t   *hap = arg2;
        const char      *history_str = hap->ha_history_str;
        objset_t        *mos = spa->spa_meta_objset;
        dmu_buf_t       *dbp;
        spa_history_phys_t *shpp;
        size_t          reclen;
        uint64_t        le_len;
        nvlist_t        *nvrecord;
        char            *record_packed = NULL;
        int             ret;

        /*
         * If we have an older pool that doesn't have a command
         * history object, create it now.
         */
        mutex_enter(&spa->spa_history_lock);
        if (!spa->spa_history)
                spa_history_create_obj(spa, tx);
        mutex_exit(&spa->spa_history_lock);

        /*
         * Get the offset of where we need to write via the bonus buffer.
         * Update the offset when the write completes.
         */
        VERIFY(0 == dmu_bonus_hold(mos, spa->spa_history, FTAG, &dbp));
        shpp = dbp->db_data;

        dmu_buf_will_dirty(dbp, tx);

#ifdef ZFS_DEBUG
        {
                dmu_object_info_t doi;
                dmu_object_info_from_db(dbp, &doi);
                ASSERT3U(doi.doi_bonus_type, ==, DMU_OT_SPA_HISTORY_OFFSETS);
        }
#endif

        VERIFY(nvlist_alloc(&nvrecord, NV_UNIQUE_NAME, KM_SLEEP) == 0);
        VERIFY(nvlist_add_uint64(nvrecord, ZPOOL_HIST_TIME,
            gethrestime_sec()) == 0);
        VERIFY(nvlist_add_uint64(nvrecord, ZPOOL_HIST_WHO,
            (uint64_t)crgetuid(cr)) == 0);
        if (hap->ha_zone[0] != '\0')
                VERIFY(nvlist_add_string(nvrecord, ZPOOL_HIST_ZONE,
                    hap->ha_zone) == 0);
#ifdef _KERNEL
        VERIFY(nvlist_add_string(nvrecord, ZPOOL_HIST_HOST,
            utsname.nodename) == 0);
#endif
        if (hap->ha_log_type == LOG_CMD_POOL_CREATE ||
            hap->ha_log_type == LOG_CMD_NORMAL) {
                VERIFY(nvlist_add_string(nvrecord, ZPOOL_HIST_CMD,
                    history_str) == 0);
        } else {
                VERIFY(nvlist_add_uint64(nvrecord, ZPOOL_HIST_INT_EVENT,
                    hap->ha_event) == 0);
                VERIFY(nvlist_add_uint64(nvrecord, ZPOOL_HIST_TXG,
                    tx->tx_txg) == 0);
                VERIFY(nvlist_add_string(nvrecord, ZPOOL_HIST_INT_STR,
                    history_str) == 0);
        }

        VERIFY(nvlist_size(nvrecord, &reclen, NV_ENCODE_XDR) == 0);
        record_packed = kmem_alloc(reclen, KM_SLEEP);

        VERIFY(nvlist_pack(nvrecord, &record_packed, &reclen,
            NV_ENCODE_XDR, KM_SLEEP) == 0);

        mutex_enter(&spa->spa_history_lock);
        if (hap->ha_log_type == LOG_CMD_POOL_CREATE)
                VERIFY(shpp->sh_eof == shpp->sh_pool_create_len);

        /* write out the packed length as little endian */
        le_len = LE_64((uint64_t)reclen);
        ret = spa_history_write(spa, &le_len, sizeof (le_len), shpp, tx);
        if (!ret)
                ret = spa_history_write(spa, record_packed, reclen, shpp, tx);

        if (!ret && hap->ha_log_type == LOG_CMD_POOL_CREATE) {
                shpp->sh_pool_create_len += sizeof (le_len) + reclen;
                shpp->sh_bof = shpp->sh_pool_create_len;
        }

        mutex_exit(&spa->spa_history_lock);
        nvlist_free(nvrecord);
        kmem_free(record_packed, reclen);
        dmu_buf_rele(dbp, FTAG);

        if (hap->ha_log_type == LOG_INTERNAL) {
                kmem_free((void*)hap->ha_history_str, HIS_MAX_RECORD_LEN);
                kmem_free(hap, sizeof (history_arg_t));
        }
}

/*
 * Write out a history event.
 */
int
spa_history_log(spa_t *spa, const char *history_str, history_log_type_t what)
{
        history_arg_t ha;

        ASSERT(what != LOG_INTERNAL);

        ha.ha_history_str = history_str;
        ha.ha_log_type = what;
        (void) strlcpy(ha.ha_zone, spa_history_zone(), sizeof (ha.ha_zone));
        return (dsl_sync_task_do(spa_get_dsl(spa), NULL, spa_history_log_sync,
            spa, &ha, 0));
}

/*
 * Read out the command history.
 */
int
spa_history_get(spa_t *spa, uint64_t *offp, uint64_t *len, char *buf)
{
        objset_t *mos = spa->spa_meta_objset;
        dmu_buf_t *dbp;
        uint64_t read_len, phys_read_off, phys_eof;
        uint64_t leftover = 0;
        spa_history_phys_t *shpp;
        int err;

        /*
         * If the command history  doesn't exist (older pool),
         * that's ok, just return ENOENT.
         */
        if (!spa->spa_history)
                return (ENOENT);

        if ((err = dmu_bonus_hold(mos, spa->spa_history, FTAG, &dbp)) != 0)
                return (err);
        shpp = dbp->db_data;

#ifdef ZFS_DEBUG
        {
                dmu_object_info_t doi;
                dmu_object_info_from_db(dbp, &doi);
                ASSERT3U(doi.doi_bonus_type, ==, DMU_OT_SPA_HISTORY_OFFSETS);
        }
#endif

        mutex_enter(&spa->spa_history_lock);
        phys_eof = spa_history_log_to_phys(shpp->sh_eof, shpp);

        if (*offp < shpp->sh_pool_create_len) {
                /* read in just the zpool create history */
                phys_read_off = *offp;
                read_len = MIN(*len, shpp->sh_pool_create_len -
                    phys_read_off);
        } else {
                /*
                 * Need to reset passed in offset to BOF if the passed in
                 * offset has since been overwritten.
                 */
                *offp = MAX(*offp, shpp->sh_bof);
                phys_read_off = spa_history_log_to_phys(*offp, shpp);

                /*
                 * Read up to the minimum of what the user passed down or
                 * the EOF (physical or logical).  If we hit physical EOF,
                 * use 'leftover' to read from the physical BOF.
                 */
                if (phys_read_off <= phys_eof) {
                        read_len = MIN(*len, phys_eof - phys_read_off);
                } else {
                        read_len = MIN(*len,
                            shpp->sh_phys_max_off - phys_read_off);
                        if (phys_read_off + *len > shpp->sh_phys_max_off) {
                                leftover = MIN(*len - read_len,
                                    phys_eof - shpp->sh_pool_create_len);
                        }
                }
        }

        /* offset for consumer to use next */
        *offp += read_len + leftover;

        /* tell the consumer how much you actually read */
        *len = read_len + leftover;

        if (read_len == 0) {
                mutex_exit(&spa->spa_history_lock);
                dmu_buf_rele(dbp, FTAG);
                return (0);
        }

        err = dmu_read(mos, spa->spa_history, phys_read_off, read_len, buf);
        if (leftover && err == 0) {
                err = dmu_read(mos, spa->spa_history, shpp->sh_pool_create_len,
                    leftover, buf + read_len);
        }
        mutex_exit(&spa->spa_history_lock);

        dmu_buf_rele(dbp, FTAG);
        return (err);
}

void
spa_history_internal_log(history_internal_events_t event, spa_t *spa,
    dmu_tx_t *tx, cred_t *cr, const char *fmt, ...)
{
        history_arg_t *hap;
        char *str;
        va_list adx;

        /*
         * If this is part of creating a pool, not everything is
         * initialized yet, so don't bother logging the internal events.
         */
        if (tx->tx_txg == TXG_INITIAL)
                return;

        hap = kmem_alloc(sizeof (history_arg_t), KM_SLEEP);
        str = kmem_alloc(HIS_MAX_RECORD_LEN, KM_SLEEP);

        va_start(adx, fmt);
        (void) vsnprintf(str, HIS_MAX_RECORD_LEN, fmt, adx);
        va_end(adx);

        hap->ha_log_type = LOG_INTERNAL;
        hap->ha_history_str = str;
        hap->ha_event = event;
        hap->ha_zone[0] = '\0';

        if (dmu_tx_is_syncing(tx)) {
                spa_history_log_sync(spa, hap, cr, tx);
        } else {
                dsl_sync_task_do_nowait(spa_get_dsl(spa), NULL,
                    spa_history_log_sync, spa, hap, 0, tx);
        }
        /* spa_history_log_sync() will free hap and str */
}