module/zfs/vdev_root.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25
  26 /*
  27  * Copyright (c) 2012 by Delphix. All rights reserved.
  28  */
  29
  30 #include <sys/zfs_context.h>
  31 #include <sys/spa.h>
  32 #include <sys/vdev_impl.h>
  33 #include <sys/zio.h>
  34 #include <sys/fs/zfs.h>
  35
  36 /*
  37  * Virtual device vector for the pool's root vdev.
  38  */
  39
  40 /*
  41  * We should be able to tolerate one failure with absolutely no damage
  42  * to our metadata.  Two failures will take out space maps, a bunch of
  43  * indirect block trees, meta dnodes, dnodes, etc.  Probably not a happy
  44  * place to live.  When we get smarter, we can liberalize this policy.
  45  * e.g. If we haven't lost two consecutive top-level vdevs, then we are
  46  * probably fine.  Adding bean counters during alloc/free can make this
  47  * future guesswork more accurate.
  48  */
  49 static int
  50 too_many_errors(vdev_t *vd, int numerrors)
  51 {
  52         ASSERT3U(numerrors, <=, vd->vdev_children);
  53         return (numerrors > 0);
  54 }
  55
  56 static int
  57 vdev_root_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize,
  58     uint64_t *ashift)
  59 {
  60         int lasterror = 0;
  61         int numerrors = 0;
  62         int c;
  63
  64         if (vd->vdev_children == 0) {
  65                 vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
  66                 return (EINVAL);
  67         }
  68
  69         vdev_open_children(vd);
  70
  71         for (c = 0; c < vd->vdev_children; c++) {
  72                 vdev_t *cvd = vd->vdev_child[c];
  73
  74                 if (cvd->vdev_open_error && !cvd->vdev_islog) {
  75                         lasterror = cvd->vdev_open_error;
  76                         numerrors++;
  77                 }
  78         }
  79
  80         if (too_many_errors(vd, numerrors)) {
  81                 vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
  82                 return (lasterror);
  83         }
  84
  85         *asize = 0;
  86         *max_asize = 0;
  87         *ashift = 0;
  88
  89         return (0);
  90 }
  91
  92 static void
  93 vdev_root_close(vdev_t *vd)
  94 {
  95         int c;
  96
  97         for (c = 0; c < vd->vdev_children; c++)
  98                 vdev_close(vd->vdev_child[c]);
  99 }
 100
 101 static void
 102 vdev_root_state_change(vdev_t *vd, int faulted, int degraded)
 103 {
 104         if (too_many_errors(vd, faulted)) {
 105                 vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
 106                     VDEV_AUX_NO_REPLICAS);
 107         } else if (degraded) {
 108                 vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
 109         } else {
 110                 vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
 111         }
 112 }
 113
 114 vdev_ops_t vdev_root_ops = {
 115         vdev_root_open,
 116         vdev_root_close,
 117         vdev_default_asize,
 118         NULL,                   /* io_start - not applicable to the root */
 119         NULL,                   /* io_done - not applicable to the root */
 120         vdev_root_state_change,
 121         NULL,
 122         NULL,
 123         VDEV_TYPE_ROOT,         /* name of this vdev type */
 124         B_FALSE                 /* not a leaf vdev */
 125 };