external/cddl/osnet/dist/uts/common/fs/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 2008 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25
  26 #include <sys/zfs_context.h>
  27 #include <sys/spa.h>
  28 #include <sys/vdev_impl.h>
  29 #include <sys/zio.h>
  30 #include <sys/fs/zfs.h>
  31
  32 /*
  33  * Virtual device vector for the pool's root vdev.
  34  */
  35
  36 /*
  37  * We should be able to tolerate one failure with absolutely no damage
  38  * to our metadata.  Two failures will take out space maps, a bunch of
  39  * indirect block trees, meta dnodes, dnodes, etc.  Probably not a happy
  40  * place to live.  When we get smarter, we can liberalize this policy.
  41  * e.g. If we haven't lost two consecutive top-level vdevs, then we are
  42  * probably fine.  Adding bean counters during alloc/free can make this
  43  * future guesswork more accurate.
  44  */
  45 static int
  46 too_many_errors(vdev_t *vd, int numerrors)
  47 {
  48         ASSERT3U(numerrors, <=, vd->vdev_children);
  49         return (numerrors > 0);
  50 }
  51
  52 static int
  53 vdev_root_open(vdev_t *vd, uint64_t *asize, uint64_t *ashift)
  54 {
  55         int c;
  56         int lasterror = 0;
  57         int numerrors = 0;
  58
  59         if (vd->vdev_children == 0) {
  60                 vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
  61                 return (EINVAL);
  62         }
  63
  64         for (c = 0; c < vd->vdev_children; c++) {
  65                 vdev_t *cvd = vd->vdev_child[c];
  66                 int error;
  67
  68                 if ((error = vdev_open(cvd)) != 0 &&
  69                     !cvd->vdev_islog) {
  70                         lasterror = error;
  71                         numerrors++;
  72                         continue;
  73                 }
  74         }
  75
  76         if (too_many_errors(vd, numerrors)) {
  77                 vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
  78                 return (lasterror);
  79         }
  80
  81         *asize = 0;
  82         *ashift = 0;
  83
  84         return (0);
  85 }
  86
  87 static void
  88 vdev_root_close(vdev_t *vd)
  89 {
  90         int c;
  91
  92         for (c = 0; c < vd->vdev_children; c++)
  93                 vdev_close(vd->vdev_child[c]);
  94 }
  95
  96 static void
  97 vdev_root_state_change(vdev_t *vd, int faulted, int degraded)
  98 {
  99         if (too_many_errors(vd, faulted)) {
 100                 vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
 101                     VDEV_AUX_NO_REPLICAS);
 102         } else if (degraded) {
 103                 vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
 104         } else {
 105                 vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
 106         }
 107 }
 108
 109 vdev_ops_t vdev_root_ops = {
 110         vdev_root_open,
 111         vdev_root_close,
 112         vdev_default_asize,
 113         NULL,                   /* io_start - not applicable to the root */
 114         NULL,                   /* io_done - not applicable to the root */
 115         vdev_root_state_change,
 116         VDEV_TYPE_ROOT,         /* name of this vdev type */
 117         B_FALSE                 /* not a leaf vdev */
 118 };