fs/zfs/vdev_root.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 2010 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright (c) 2013 by Delphix. All rights reserved.
 */

#include <sys/zfs_context.h>
#include <sys/spa.h>
#include <sys/vdev_impl.h>
#include <sys/zio.h>
#include <sys/fs/zfs.h>

/*
 * Virtual device vector for the pool's root vdev.
 */

/*
 * We should be able to tolerate one failure with absolutely no damage
 * to our metadata.  Two failures will take out space maps, a bunch of
 * indirect block trees, meta dnodes, dnodes, etc.  Probably not a happy
 * place to live.  When we get smarter, we can liberalize this policy.
 * e.g. If we haven't lost two consecutive top-level vdevs, then we are
 * probably fine.  Adding bean counters during alloc/free can make this
 * future guesswork more accurate.
 */
static int
too_many_errors(vdev_t *vd, int numerrors)
{
    ASSERT3U(numerrors, <=, vd->vdev_children);
    return (numerrors > 0);
}

static int
vdev_root_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize,
    uint64_t *ashift)
{
    int lasterror = 0;
    int numerrors = 0;

    if (vd->vdev_children == 0) {
        vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
        return (SET_ERROR(EINVAL));
    }

    vdev_open_children(vd);

    for (int c = 0; c < vd->vdev_children; c++) {
        vdev_t *cvd = vd->vdev_child[c];

        if (cvd->vdev_open_error && !cvd->vdev_islog) {
            lasterror = cvd->vdev_open_error;
            numerrors++;
        }
    }

    if (too_many_errors(vd, numerrors)) {
        vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
        return (lasterror);
    }

    *asize = 0;
    *max_asize = 0;
    *ashift = 0;

    return (0);
}

static void
vdev_root_close(vdev_t *vd)
{
    for (int c = 0; c < vd->vdev_children; c++)
        vdev_close(vd->vdev_child[c]);
}

static void
vdev_root_state_change(vdev_t *vd, int faulted, int degraded)
{
    if (too_many_errors(vd, faulted)) {
        vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
            VDEV_AUX_NO_REPLICAS);
    } else if (degraded) {
        vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
    } else {
        vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
    }
}

vdev_ops_t vdev_root_ops = {
    vdev_root_open,
    vdev_root_close,
    vdev_default_asize,
    NULL,           /* io_start - not applicable to the root */
    NULL,           /* io_done - not applicable to the root */
    vdev_root_state_change,
    NULL,
    NULL,
    VDEV_TYPE_ROOT,     /* name of this vdev type */
    B_FALSE         /* not a leaf vdev */
};