FreeBSD/Linux Kernel Cross Reference
sys/dev/vinum/vinumdaemon.c

     /* daemon.c: kernel part of Vinum daemon */
     /*-
      * Copyright (c) 1997, 1998
      *      Nan Yang Computer Services Limited.  All rights reserved.
      *
      *  This software is distributed under the so-called ``Berkeley
      *  License'':
      *
      * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by Nan Yang Computer
     *      Services Limited.
     * 4. Neither the name of the Company nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * This software is provided ``as is'', and any express or implied
     * warranties, including, but not limited to, the implied warranties of
     * merchantability and fitness for a particular purpose are disclaimed.
     * In no event shall the company or contributors be liable for any
     * direct, indirect, incidental, special, exemplary, or consequential
     * damages (including, but not limited to, procurement of substitute
     * goods or services; loss of use, data, or profits; or business
     * interruption) however caused and on any theory of liability, whether
     * in contract, strict liability, or tort (including negligence or
     * otherwise) arising in any way out of the use of this software, even if
     * advised of the possibility of such damage.
     *
     * $Id: vinumdaemon.c,v 1.2 2003/11/25 20:11:59 jdolecek Exp $
     * $FreeBSD$
     */
    
    #include <dev/vinum/vinumhdr.h>
    #include <dev/vinum/request.h>
    
    #ifdef VINUMDEBUG
    #include <sys/reboot.h>
    #endif
    
    /* declarations */
    void recover_io(struct request *rq);
    
    int daemon_options = 0;                                     /* options */
    int daemonpid;                                              /* PID of daemon */
    struct daemonq *daemonq;                                    /* daemon's work queue */
    struct daemonq *dqend;                                      /* and the end of the queue */
    
    /*
     * We normally call Malloc to get a queue element.  In interrupt
     * context, we can't guarantee that we'll get one, since we're not
     * allowed to wait.  If malloc fails, use one of these elements.
     */
    
    #define INTQSIZE 4
    struct daemonq intq[INTQSIZE];                              /* queue elements for interrupt context */
    struct daemonq *intqp;                                      /* and pointer in it */
    
    void
    vinum_daemon(void)
    {
        int s;
        struct daemonq *request;
    
        curproc->p_flag |= P_SYSTEM;                            /* we're a system process */
        daemon_save_config();                                   /* start by saving the configuration */
        daemonpid = curproc->p_pid;                             /* mark our territory */
        while (1) {
            tsleep(&vinum_daemon, PRIBIO, "vinum", 0);          /* wait for something to happen */
    
            /*
             * It's conceivable that, as the result of an
             * I/O error, we'll be out of action long
             * enough that another daemon gets started.
             * That's OK, just give up gracefully.
             */
            if (curproc->p_pid != daemonpid) {                  /* we've been ousted in our sleep */
                if (daemon_options & daemon_verbose)
                    log(LOG_INFO, "vinum: abdicating\n");
                return;
            }
            while (daemonq != NULL) {                           /* we have work to do, */
                s = splhigh();                                  /* don't get interrupted here */
                request = daemonq;                              /* get the request */
                daemonq = daemonq->next;                        /* and detach it */
                if (daemonq == NULL)                            /* got to the end, */
                    dqend = NULL;                               /* no end any more */
                splx(s);
    
                switch (request->type) {
                    /*
                     * We had an I/O error on a request.  Go through the
                    * request and try to salvage it
                    */
               case daemonrq_ioerror:
                   if (daemon_options & daemon_verbose) {
                       struct request *rq = request->info.rq;
   
                       log(LOG_WARNING,
                           "vinum: recovering I/O request: %p\n%s dev %d.%d, offset 0x%llx, length %ld\n",
                           rq,
                           rq->bp->b_flags & B_READ ? "Read" : "Write",
                           major(rq->bp->b_dev),
                           minor(rq->bp->b_dev),
                           (long long int) rq->bp->b_blkno,
                           rq->bp->b_bcount);
                   }
                   recover_io(request->info.rq);               /* the failed request */
                   break;
   
                   /*
                    * Write the config to disk.  We could end up with
                    * quite a few of these in a row.  Only honour the
                    * last one
                    */
               case daemonrq_saveconfig:
                   if ((daemonq == NULL)                       /* no more requests */
                   ||(daemonq->type != daemonrq_saveconfig)) { /* or the next isn't the same */
                       if (((daemon_options & daemon_noupdate) == 0) /* we're allowed to do it */
                       &&((vinum_conf.flags & VF_READING_CONFIG) == 0)) { /* and we're not building the config now */
                           /*
                              * We obviously don't want to save a
                              * partial configuration.  Less obviously,
                              * we don't need to do anything if we're
                              * asked to write the config when we're
                              * building it up, because we save it at
                              * the end.
                            */
                           if (daemon_options & daemon_verbose)
                               log(LOG_INFO, "vinum: saving config\n");
                           daemon_save_config();               /* save it */
                       }
                   }
                   break;
   
               case daemonrq_return:                           /* been told to stop */
                   if (daemon_options & daemon_verbose)
                       log(LOG_INFO, "vinum: stopping\n");
                   daemon_options |= daemon_stopped;           /* note that we've stopped */
                   Free(request);
                   while (daemonq != NULL) {                   /* backed up requests, */
                       request = daemonq;                      /* get the request */
                       daemonq = daemonq->next;                /* and detach it */
                       Free(request);                          /* then free it */
                   }
                   wakeup(&vinumclose);                        /* and wake any waiting vinum(8)s */
                   return;
   
               case daemonrq_ping:                             /* tell the caller we're here */
                   if (daemon_options & daemon_verbose)
                       log(LOG_INFO, "vinum: ping reply\n");
                   wakeup(&vinum_finddaemon);                  /* wake up the caller */
                   break;
   
               case daemonrq_closedrive:                       /* close a drive */
                   close_drive(request->info.drive);           /* do it */
                   break;
   
               case daemonrq_init:                             /* initialize a plex */
                   /* XXX */
               case daemonrq_revive:                           /* revive a subdisk */
                   /* XXX */
                   /* FALLTHROUGH */
               default:
                   log(LOG_WARNING, "Invalid request\n");
                   break;
               }
               if (request->privateinuse)                      /* one of ours, */
                   request->privateinuse = 0;                  /* no longer in use */
               else
                   Free(request);                              /* return it */
           }
       }
   }
   
   /*
    * Recover a failed I/O operation.
    *
    * The correct way to do this is to examine the request and determine
    * how to recover each individual failure.  In the case of a write,
    * this could be as simple as doing nothing: the defective drives may
    * already be down, and there may be nothing else to do.  In case of
    * a read, it will be necessary to retry if there are alternative
    * copies of the data.
    *
    * The easy way (here) is just to reissue the request.  This will take
    * a little longer, but nothing like as long as the failure will have
    * taken.
    *
    */
   void
   recover_io(struct request *rq)
   {
       vinumstrategy(rq->bp);                                  /* reissue the command */
   }
   
   /* Functions called to interface with the daemon */
   
   /* queue a request for the daemon */
   void
   queue_daemon_request(enum daemonrq type, union daemoninfo info)
   {
       int s;
   
       struct daemonq *qelt = (struct daemonq *) Malloc(sizeof(struct daemonq));
   
       if (qelt == NULL) {                                     /* malloc failed, we're prepared for that */
           /*
            * Take one of our spares.  Give up if it's still in use; the only
            * message we're likely to get here is a 'drive failed' message,
            * and that'll come by again if we miss it.
            */
           if (intqp->privateinuse)                            /* still in use? */
               return;                                         /* yes, give up */
           qelt = intqp++;
           if (intqp == &intq[INTQSIZE])                       /* got to the end, */
               intqp = intq;                                   /* wrap around */
           qelt->privateinuse = 1;                             /* it's ours, and it's in use */
       } else
           qelt->privateinuse = 0;
   
       qelt->next = NULL;                                      /* end of the chain */
       qelt->type = type;
       qelt->info = info;
       s = splhigh();
       if (daemonq) {                                          /* something queued already */
           dqend->next = qelt;
           dqend = qelt;
       } else {                                                /* queue is empty, */
           daemonq = qelt;                                     /* this is the whole queue */
           dqend = qelt;
       }
       splx(s);
       wakeup(&vinum_daemon);                                  /* and give the dæmon a kick */
   }
   
   /*
    * see if the daemon is running.  Return 0 (no error)
    * if it is, ESRCH otherwise
    */
   int
   vinum_finddaemon()
   {
       int result;
   
       if (daemonpid != 0) {                                   /* we think we have a daemon, */
           queue_daemon_request(daemonrq_ping, (union daemoninfo) 0); /* queue a ping */
           result = tsleep(&vinum_finddaemon, PUSER, "reap", 2 * hz);
           if (result == 0)                                    /* yup, the daemon's up and running */
               return 0;
       }
       /* no daemon, or we couldn't talk to it: start it */
       vinum_daemon();                                         /* start the daemon */
       return 0;
   }
   
   int
   vinum_setdaemonopts(int options)
   {
       daemon_options = options;
       return 0;
   }

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