FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/module/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 https://opensource.org/licenses/CDDL-1.0.
     * 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) 2012, 2016 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.
     */
    
    static uint64_t
    vdev_root_core_tvds(vdev_t *vd)
    {
            uint64_t tvds = 0;
    
            for (uint64_t c = 0; c < vd->vdev_children; c++) {
                    vdev_t *cvd = vd->vdev_child[c];
    
                    if (!cvd->vdev_ishole && !cvd->vdev_islog &&
                        cvd->vdev_ops != &vdev_indirect_ops) {
                            tvds++;
                    }
            }
    
            return (tvds);
    }
    
    /*
     * 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 boolean_t
    too_many_errors(vdev_t *vd, uint64_t numerrors)
    {
            uint64_t tvds;
    
            if (numerrors == 0)
                    return (B_FALSE);
    
            tvds = vdev_root_core_tvds(vd);
            ASSERT3U(numerrors, <=, tvds);
    
            if (numerrors == tvds)
                    return (B_TRUE);
    
            return (numerrors > spa_missing_tvds_allowed(vd->vdev_spa));
    }
    
    static int
    vdev_root_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize,
        uint64_t *ashift, uint64_t *pshift)
    {
            spa_t *spa = vd->vdev_spa;
            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 &&
                       cvd->vdev_ops != &vdev_indirect_ops) {
                           lasterror = cvd->vdev_open_error;
                           numerrors++;
                   }
           }
   
           if (spa_load_state(spa) != SPA_LOAD_NONE)
                   spa_set_missing_tvds(spa, 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;
           *pshift = 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 || faulted) {
                   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_op_init = NULL,
           .vdev_op_fini = NULL,
           .vdev_op_open = vdev_root_open,
           .vdev_op_close = vdev_root_close,
           .vdev_op_asize = vdev_default_asize,
           .vdev_op_min_asize = vdev_default_min_asize,
           .vdev_op_min_alloc = NULL,
           .vdev_op_io_start = NULL,       /* not applicable to the root */
           .vdev_op_io_done = NULL,        /* not applicable to the root */
           .vdev_op_state_change = vdev_root_state_change,
           .vdev_op_need_resilver = NULL,
           .vdev_op_hold = NULL,
           .vdev_op_rele = NULL,
           .vdev_op_remap = NULL,
           .vdev_op_xlate = NULL,
           .vdev_op_rebuild_asize = NULL,
           .vdev_op_metaslab_init = NULL,
           .vdev_op_config_generate = NULL,
           .vdev_op_nparity = NULL,
           .vdev_op_ndisks = NULL,
           .vdev_op_type = VDEV_TYPE_ROOT, /* name of this vdev type */
           .vdev_op_leaf = B_FALSE         /* not a leaf vdev */
   };

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