fs/zfs/dmu_traverse.c

	dmu_traverse.c revision b24ab6762772a3f6a89393947930c7fa61306783
/*
 * 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.
 */

#include <sys/zfs_context.h>
#include <sys/dmu_objset.h>
#include <sys/dmu_traverse.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_dir.h>
#include <sys/dsl_pool.h>
#include <sys/dnode.h>
#include <sys/spa.h>
#include <sys/zio.h>
#include <sys/dmu_impl.h>
#include <sys/callb.h>

struct prefetch_data {
    kmutex_t pd_mtx;
    kcondvar_t pd_cv;
    int pd_blks_max;
    int pd_blks_fetched;
    int pd_flags;
    boolean_t pd_cancel;
    boolean_t pd_exited;
};

struct traverse_data {
    spa_t *td_spa;
    uint64_t td_objset;
    blkptr_t *td_rootbp;
    uint64_t td_min_txg;
    int td_flags;
    struct prefetch_data *td_pfd;
    blkptr_cb_t *td_func;
    void *td_arg;
};

static int traverse_dnode(struct traverse_data *td, const dnode_phys_t *dnp,
    arc_buf_t *buf, uint64_t objset, uint64_t object);

/* ARGSUSED */
static int
traverse_zil_block(zilog_t *zilog, blkptr_t *bp, void *arg, uint64_t claim_txg)
{
    struct traverse_data *td = arg;
    zbookmark_t zb;

    if (bp->blk_birth == 0)
        return (0);

    if (claim_txg == 0 && bp->blk_birth >= spa_first_txg(td->td_spa))
        return (0);

    SET_BOOKMARK(&zb, td->td_objset, ZB_ZIL_OBJECT, ZB_ZIL_LEVEL,
        bp->blk_cksum.zc_word[ZIL_ZC_SEQ]);

    (void) td->td_func(td->td_spa, zilog, bp, &zb, NULL, td->td_arg);

    return (0);
}

/* ARGSUSED */
static int
traverse_zil_record(zilog_t *zilog, lr_t *lrc, void *arg, uint64_t claim_txg)
{
    struct traverse_data *td = arg;

    if (lrc->lrc_txtype == TX_WRITE) {
        lr_write_t *lr = (lr_write_t *)lrc;
        blkptr_t *bp = &lr->lr_blkptr;
        zbookmark_t zb;

        if (bp->blk_birth == 0)
            return (0);

        if (claim_txg == 0 || bp->blk_birth < claim_txg)
            return (0);

        SET_BOOKMARK(&zb, td->td_objset, lr->lr_foid, ZB_ZIL_LEVEL,
            lr->lr_offset / BP_GET_LSIZE(bp));

        (void) td->td_func(td->td_spa, zilog, bp, &zb, NULL,
            td->td_arg);
    }
    return (0);
}

static void
traverse_zil(struct traverse_data *td, zil_header_t *zh)
{
    uint64_t claim_txg = zh->zh_claim_txg;
    zilog_t *zilog;

    /*
     * We only want to visit blocks that have been claimed but not yet
     * replayed; plus, in read-only mode, blocks that are already stable.
     */
    if (claim_txg == 0 && spa_writeable(td->td_spa))
        return;

    zilog = zil_alloc(spa_get_dsl(td->td_spa)->dp_meta_objset, zh);

    (void) zil_parse(zilog, traverse_zil_block, traverse_zil_record, td,
        claim_txg);

    zil_free(zilog);
}

static int
traverse_visitbp(struct traverse_data *td, const dnode_phys_t *dnp,
    arc_buf_t *pbuf, blkptr_t *bp, const zbookmark_t *zb)
{
    zbookmark_t czb;
    int err = 0;
    arc_buf_t *buf = NULL;
    struct prefetch_data *pd = td->td_pfd;

    if (bp->blk_birth == 0) {
        err = td->td_func(td->td_spa, NULL, NULL, zb, dnp, td->td_arg);
        return (err);
    }

    if (bp->blk_birth <= td->td_min_txg)
        return (0);

    if (pd && !pd->pd_exited &&
        ((pd->pd_flags & TRAVERSE_PREFETCH_DATA) ||
        BP_GET_TYPE(bp) == DMU_OT_DNODE || BP_GET_LEVEL(bp) > 0)) {
        mutex_enter(&pd->pd_mtx);
        ASSERT(pd->pd_blks_fetched >= 0);
        while (pd->pd_blks_fetched == 0 && !pd->pd_exited)
            cv_wait(&pd->pd_cv, &pd->pd_mtx);
        pd->pd_blks_fetched--;
        cv_broadcast(&pd->pd_cv);
        mutex_exit(&pd->pd_mtx);
    }

    if (td->td_flags & TRAVERSE_PRE) {
        err = td->td_func(td->td_spa, NULL, bp, zb, dnp, td->td_arg);
        if (err)
            return (err);
    }

    if (BP_GET_LEVEL(bp) > 0) {
        uint32_t flags = ARC_WAIT;
        int i;
        blkptr_t *cbp;
        int epb = BP_GET_LSIZE(bp) >> SPA_BLKPTRSHIFT;

        err = arc_read(NULL, td->td_spa, bp, pbuf,
            arc_getbuf_func, &buf,
            ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
        if (err)
            return (err);

        /* recursively visitbp() blocks below this */
        cbp = buf->b_data;
        for (i = 0; i < epb; i++, cbp++) {
            SET_BOOKMARK(&czb, zb->zb_objset, zb->zb_object,
                zb->zb_level - 1,
                zb->zb_blkid * epb + i);
            err = traverse_visitbp(td, dnp, buf, cbp, &czb);
            if (err)
                break;
        }
    } else if (BP_GET_TYPE(bp) == DMU_OT_DNODE) {
        uint32_t flags = ARC_WAIT;
        int i;
        int epb = BP_GET_LSIZE(bp) >> DNODE_SHIFT;

        err = arc_read(NULL, td->td_spa, bp, pbuf,
            arc_getbuf_func, &buf,
            ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
        if (err)
            return (err);

        /* recursively visitbp() blocks below this */
        dnp = buf->b_data;
        for (i = 0; i < epb && err == 0; i++, dnp++) {
            err = traverse_dnode(td, dnp, buf, zb->zb_objset,
                zb->zb_blkid * epb + i);
            if (err)
                break;
        }
    } else if (BP_GET_TYPE(bp) == DMU_OT_OBJSET) {
        uint32_t flags = ARC_WAIT;
        objset_phys_t *osp;
        dnode_phys_t *dnp;

        err = arc_read_nolock(NULL, td->td_spa, bp,
            arc_getbuf_func, &buf,
            ZIO_PRIORITY_ASYNC_READ, ZIO_FLAG_CANFAIL, &flags, zb);
        if (err)
            return (err);

        osp = buf->b_data;
        traverse_zil(td, &osp->os_zil_header);

        dnp = &osp->os_meta_dnode;
        err = traverse_dnode(td, dnp, buf, zb->zb_objset,
            DMU_META_DNODE_OBJECT);
        if (err == 0 && arc_buf_size(buf) >= sizeof (objset_phys_t)) {
            dnp = &osp->os_userused_dnode;
            err = traverse_dnode(td, dnp, buf, zb->zb_objset,
                DMU_USERUSED_OBJECT);
        }
        if (err == 0 && arc_buf_size(buf) >= sizeof (objset_phys_t)) {
            dnp = &osp->os_groupused_dnode;
            err = traverse_dnode(td, dnp, buf, zb->zb_objset,
                DMU_GROUPUSED_OBJECT);
        }
    }

    if (buf)
        (void) arc_buf_remove_ref(buf, &buf);

    if (err == 0 && (td->td_flags & TRAVERSE_POST))
        err = td->td_func(td->td_spa, NULL, bp, zb, dnp, td->td_arg);

    return (err);
}

static int
traverse_dnode(struct traverse_data *td, const dnode_phys_t *dnp,
    arc_buf_t *buf, uint64_t objset, uint64_t object)
{
    int j, err = 0;
    zbookmark_t czb;

    for (j = 0; j < dnp->dn_nblkptr; j++) {
        SET_BOOKMARK(&czb, objset, object, dnp->dn_nlevels - 1, j);
        err = traverse_visitbp(td, dnp, buf,
            (blkptr_t *)&dnp->dn_blkptr[j], &czb);
        if (err)
            break;
    }
    return (err);
}

/* ARGSUSED */
static int
traverse_prefetcher(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
    const zbookmark_t *zb, const dnode_phys_t *dnp, void *arg)
{
    struct prefetch_data *pfd = arg;
    uint32_t aflags = ARC_NOWAIT | ARC_PREFETCH;

    ASSERT(pfd->pd_blks_fetched >= 0);
    if (pfd->pd_cancel)
        return (EINTR);

    if (bp == NULL || !((pfd->pd_flags & TRAVERSE_PREFETCH_DATA) ||
        BP_GET_TYPE(bp) == DMU_OT_DNODE || BP_GET_LEVEL(bp) > 0))
        return (0);

    mutex_enter(&pfd->pd_mtx);
    while (!pfd->pd_cancel && pfd->pd_blks_fetched >= pfd->pd_blks_max)
        cv_wait(&pfd->pd_cv, &pfd->pd_mtx);
    pfd->pd_blks_fetched++;
    cv_broadcast(&pfd->pd_cv);
    mutex_exit(&pfd->pd_mtx);

    (void) arc_read_nolock(NULL, spa, bp, NULL, NULL,
        ZIO_PRIORITY_ASYNC_READ,
        ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
        &aflags, zb);

    return (0);
}

static void
traverse_prefetch_thread(void *arg)
{
    struct traverse_data *td_main = arg;
    struct traverse_data td = *td_main;
    zbookmark_t czb;

    td.td_func = traverse_prefetcher;
    td.td_arg = td_main->td_pfd;
    td.td_pfd = NULL;

    SET_BOOKMARK(&czb, td.td_objset,
        ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
    (void) traverse_visitbp(&td, NULL, NULL, td.td_rootbp, &czb);

    mutex_enter(&td_main->td_pfd->pd_mtx);
    td_main->td_pfd->pd_exited = B_TRUE;
    cv_broadcast(&td_main->td_pfd->pd_cv);
    mutex_exit(&td_main->td_pfd->pd_mtx);
}

/*
 * NB: dataset must not be changing on-disk (eg, is a snapshot or we are
 * in syncing context).
 */
static int
traverse_impl(spa_t *spa, uint64_t objset, blkptr_t *rootbp,
    uint64_t txg_start, int flags, blkptr_cb_t func, void *arg)
{
    struct traverse_data td;
    struct prefetch_data pd = { 0 };
    zbookmark_t czb;
    int err;

    td.td_spa = spa;
    td.td_objset = objset;
    td.td_rootbp = rootbp;
    td.td_min_txg = txg_start;
    td.td_func = func;
    td.td_arg = arg;
    td.td_pfd = &pd;
    td.td_flags = flags;

    pd.pd_blks_max = 100;
    pd.pd_flags = flags;
    mutex_init(&pd.pd_mtx, NULL, MUTEX_DEFAULT, NULL);
    cv_init(&pd.pd_cv, NULL, CV_DEFAULT, NULL);

    if (!(flags & TRAVERSE_PREFETCH) ||
        0 == taskq_dispatch(system_taskq, traverse_prefetch_thread,
        &td, TQ_NOQUEUE))
        pd.pd_exited = B_TRUE;

    SET_BOOKMARK(&czb, objset,
        ZB_ROOT_OBJECT, ZB_ROOT_LEVEL, ZB_ROOT_BLKID);
    err = traverse_visitbp(&td, NULL, NULL, rootbp, &czb);

    mutex_enter(&pd.pd_mtx);
    pd.pd_cancel = B_TRUE;
    cv_broadcast(&pd.pd_cv);
    while (!pd.pd_exited)
        cv_wait(&pd.pd_cv, &pd.pd_mtx);
    mutex_exit(&pd.pd_mtx);

    mutex_destroy(&pd.pd_mtx);
    cv_destroy(&pd.pd_cv);

    return (err);
}

/*
 * NB: dataset must not be changing on-disk (eg, is a snapshot or we are
 * in syncing context).
 */
int
traverse_dataset(dsl_dataset_t *ds, uint64_t txg_start, int flags,
    blkptr_cb_t func, void *arg)
{
    return (traverse_impl(ds->ds_dir->dd_pool->dp_spa, ds->ds_object,
        &ds->ds_phys->ds_bp, txg_start, flags, func, arg));
}

/*
 * NB: pool must not be changing on-disk (eg, from zdb or sync context).
 */
int
traverse_pool(spa_t *spa, blkptr_cb_t func, void *arg, uint64_t txg_start)
{
    int err;
    uint64_t obj;
    dsl_pool_t *dp = spa_get_dsl(spa);
    objset_t *mos = dp->dp_meta_objset;

    /* visit the MOS */
    err = traverse_impl(spa, 0, spa_get_rootblkptr(spa),
        txg_start, TRAVERSE_PRE | TRAVERSE_PREFETCH, func, arg);
    if (err)
        return (err);

    /* visit each dataset */
    for (obj = 1; err == 0; err = dmu_object_next(mos, &obj, FALSE,
        txg_start)) {
        dmu_object_info_t doi;

        err = dmu_object_info(mos, obj, &doi);
        if (err)
            return (err);

        if (doi.doi_type == DMU_OT_DSL_DATASET) {
            dsl_dataset_t *ds;
            uint64_t txg = txg_start;

            rw_enter(&dp->dp_config_rwlock, RW_READER);
            err = dsl_dataset_hold_obj(dp, obj, FTAG, &ds);
            rw_exit(&dp->dp_config_rwlock);
            if (err)
                return (err);
            if (ds->ds_phys->ds_prev_snap_txg > txg)
                txg = ds->ds_phys->ds_prev_snap_txg;
            err = traverse_dataset(ds, txg,
                TRAVERSE_PRE | TRAVERSE_PREFETCH, func, arg);
            dsl_dataset_rele(ds, FTAG);
            if (err)
                return (err);
        }
    }
    if (err == ESRCH)
        err = 0;
    return (err);
}