e0e19a088b
Don't save config while we're reading it from disk. Change the way we handle the daemon: if we can't communicate with it for 1 second (which is possible), start a new one. The daemon saves its pid in daemonpid; on each iteration of the main loop the daemon checks whether it's still in favour. If not, it silently exits. Also, when trying to communicate with the daemon, check daemonpid first. If it's set to 0, don't even try.
227 lines
7.3 KiB
C
227 lines
7.3 KiB
C
/* daemon.c: kernel part of Vinum daemon */
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/*-
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* Copyright (c) 1997, 1998
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* Nan Yang Computer Services Limited. All rights reserved.
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*
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* This software is distributed under the so-called ``Berkeley
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* License'':
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Nan Yang Computer
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* Services Limited.
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* 4. Neither the name of the Company nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* This software is provided ``as is'', and any express or implied
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* warranties, including, but not limited to, the implied warranties of
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* merchantability and fitness for a particular purpose are disclaimed.
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* In no event shall the company or contributors be liable for any
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* direct, indirect, incidental, special, exemplary, or consequential
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* damages (including, but not limited to, procurement of substitute
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* goods or services; loss of use, data, or profits; or business
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* interruption) however caused and on any theory of liability, whether
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* in contract, strict liability, or tort (including negligence or
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* otherwise) arising in any way out of the use of this software, even if
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* advised of the possibility of such damage.
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*
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* $Id: vinumdaemon.c,v 1.3 1999/01/18 04:32:50 grog Exp grog $
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*/
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#define REALLYKERNEL
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#include <dev/vinum/vinumhdr.h>
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#include <dev/vinum/request.h>
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#ifdef VINUMDEBUG
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#include <sys/reboot.h>
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#endif
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/* declarations */
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void recover_io(struct request *rq);
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struct daemonq *daemonq; /* daemon's work queue */
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struct daemonq *dqend; /* and the end of the queue */
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int daemon_options = 0; /* options */
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int daemonpid; /* PID of daemon */
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void
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vinum_daemon(void)
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{
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struct daemonq *request;
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int s;
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daemon_save_config(); /* start by saving the configuration */
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daemonpid = curproc->p_pid; /* mark our territory */
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while (1) {
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tsleep(&vinum_daemon, PRIBIO, "vinum", 0); /* wait for something to happen */
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/*
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* It's conceivable that, as the result of an
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* I/O error, we'll be out of action long
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* enough that another daemon gets started.
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* That's OK, just give up gracefully.
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*/
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if (curproc->p_pid != daemonpid) { /* we've been ousted in our sleep */
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if (daemon_options & daemon_verbose)
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log(LOG_INFO, "vinumd: abdicating\n");
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return;
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}
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while (daemonq != NULL) { /* we have work to do, */
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s = splhigh(); /* don't get interrupted here */
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request = daemonq; /* get the request */
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daemonq = daemonq->next; /* and detach it */
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if (daemonq == NULL) /* got to the end, */
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dqend = NULL; /* no end any more */
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splx(s);
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switch (request->type) {
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/*
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* We had an I/O error on a request. Go through the
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* request and try to salvage it
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*/
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case daemonrq_ioerror:
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if (daemon_options & daemon_verbose) {
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struct request *rq = request->info.rq;
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log(LOG_WARNING,
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"vinumd: recovering I/O request: %x\n%s dev 0x%x, offset 0x%x, length %ld\n",
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(u_int) rq,
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rq->bp->b_flags & B_READ ? "Read" : "Write",
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rq->bp->b_dev,
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rq->bp->b_blkno,
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rq->bp->b_bcount);
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}
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recover_io(request->info.rq); /* the failed request */
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break;
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/*
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* Write the config to disk. We could end up with
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* quite a few of these in a row. Only honour the
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* last one
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*/
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case daemonrq_saveconfig:
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if ((daemonq == NULL) /* no more requests */
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||(daemonq->type != daemonrq_saveconfig)) { /* or the next isn't the same */
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if (((daemon_options & daemon_noupdate) == 0) /* we're allowed to do it */
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&&((vinum_conf.flags & VF_READING_CONFIG) == 0)) { /* and we're not building the config now */
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/*
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* We obviously don't want to save a
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* partial configuration. Less obviously,
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* we don't need to do anything if we're
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* asked to write the config when we're
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* building it up, because we save it at
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* the end.
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*/
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if (daemon_options & daemon_verbose)
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log(LOG_INFO, "vinumd: saving config\n");
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daemon_save_config(); /* save it */
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}
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}
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break;
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case daemonrq_return: /* been told to stop */
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if (daemon_options & daemon_verbose)
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log(LOG_INFO, "vinumd: stopping\n");
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daemon_options |= daemon_stopped; /* note that we've stopped */
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return;
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case daemonrq_ping: /* tell the caller we're here */
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if (daemon_options & daemon_verbose)
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log(LOG_INFO, "vinumd: ping reply\n");
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wakeup(&vinum_finddaemon); /* wake up the caller */
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break;
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case daemonrq_init: /* initialize a plex */
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/* XXX */
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case daemonrq_revive: /* revive a subdisk */
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/* XXX */
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default:
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log(LOG_WARNING, "Invalid request\n");
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break;
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}
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Free(request);
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}
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}
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}
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/*
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* Recover a failed I/O operation.
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*
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* The correct way to do this is to examine the request and determine
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* how to recover each individual failure. In the case of a write,
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* this could be as simple as doing nothing: the defective drives may
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* already be down, and there may be nothing else to do. In case of
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* a read, it will be necessary to retry if there are alternative
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* copies of the data.
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*
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* The easy way (here) is just to reissue the request. This will take
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* a little longer, but nothing like as long as the failure will have
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* taken.
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*
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*/
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void
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recover_io(struct request *rq)
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{
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vinumstrategy(rq->bp); /* reissue the command */
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}
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/* Functions called to interface with the daemon */
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/* queue a request for the daemon */
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void
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queue_daemon_request(enum daemonrq type, union daemoninfo info)
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{
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int s;
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struct daemonq *qelt = (struct daemonq *) Malloc(sizeof(struct daemonq));
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qelt->next = NULL; /* end of the chain */
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qelt->type = type;
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qelt->info = info;
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s = splhigh();
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if (daemonq) { /* something queued already */
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dqend->next = qelt;
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dqend = qelt;
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} else { /* queue is empty, */
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daemonq = qelt; /* this is the whole queue */
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dqend = qelt;
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}
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splx(s);
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wakeup(&vinum_daemon); /* and give the d<>mon a kick */
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}
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/*
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* see if the daemon is running. Return 0 (no error)
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* if it is, ESRCH otherwise
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*/
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int
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vinum_finddaemon()
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{
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int result;
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if (daemonpid != 0) { /* we think we have a daemon, */
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queue_daemon_request(daemonrq_ping, NULL); /* queue a ping */
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result = tsleep(&vinum_finddaemon, PUSER, "reap", 2 * hz);
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if (result == 0) /* yup, the daemon's up and running */
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return 0;
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}
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/* no daemon, or we couldn't talk to it: start it */
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vinum_daemon(); /* start the daemon */
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return 0;
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}
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int
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vinum_setdaemonopts(int options)
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{
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daemon_options = options;
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return 0;
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}
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