freebsd/sys/dev/vinum/vinumlock.c

/*-
 * 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: vinumlock.c,v 1.9 1999/03/13 03:26:00 grog Exp grog $
 */

#include <dev/vinum/vinumhdr.h>

/*
 * Lock routines.  Currently, we lock either an individual volume
 * or the global configuration.  I don't think tsleep and
 * wakeup are SMP safe. FIXME XXX
 */

/* Lock a drive, wait if it's in use */
#if VINUMDEBUG
int 
lockdrive(struct drive *drive, char *file, int line)
#else
int 
lockdrive(struct drive *drive)
#endif
{
    int error;

    /* XXX get rid of     drive->flags |= VF_LOCKING; */
    if ((drive->flags & VF_LOCKED)			    /* it's locked */
    &&(drive->pid == curproc->p_pid)) {			    /* by us! */
#ifdef VINUMDEBUG
	log(LOG_WARNING,
	    "vinum lockdrive: already locking %s from %s:%d, called from %s:%d\n",
	    drive->label.name,
	    drive->lockfilename,
	    drive->lockline,
	    basename(file),
	    line);
#else
	log(LOG_WARNING,
	    "vinum lockdrive: already locking %s\n",
	    drive->label.name);
#endif
	return 0;
    }
    while ((drive->flags & VF_LOCKED) != 0) {
	/*
	 * There are problems sleeping on a unique identifier,
	 * since the drive structure can move, and the unlock
	 * function can be called after killing the drive.
	 * Solve this by waiting on this function; the number
	 * of conflicts is negligible.
	 */
	if ((error = tsleep(&lockdrive,
		    PRIBIO | PCATCH,
		    "vindrv",
		    0)) != 0)
	    return error;
    }
    drive->flags |= VF_LOCKED;
    drive->pid = curproc->p_pid;			    /* it's a panic error if curproc is null */
#ifdef VINUMDEBUG
    bcopy(basename(file), drive->lockfilename, 15);
    drive->lockfilename[15] = '\0';			    /* truncate if necessary */
    drive->lockline = line;
#endif
    return 0;
}

/* Unlock a drive and let the next one at it */
void 
unlockdrive(struct drive *drive)
{
    drive->flags &= ~VF_LOCKED;
    /* we don't reset pid: it's of hysterical interest */
    wakeup(&lockdrive);
}

/* Lock a volume, wait if it's in use */
int 
lockvol(struct volume *vol)
{
    int error;

    while ((vol->flags & VF_LOCKED) != 0) {
	vol->flags |= VF_LOCKING;
	/*
	 * It would seem to make more sense to sleep on
	 * the address 'vol'.  Unfortuntaly we can't
	 * guarantee that this address won't change due to
	 * table expansion.  The address we choose won't change.
	 */
	if ((error = tsleep(&vinum_conf.volume + vol->volno,
		    PRIBIO | PCATCH,
		    "volock",
		    0)) != 0)
	    return error;
    }
    vol->flags |= VF_LOCKED;
    return 0;
}

/* Unlock a volume and let the next one at it */
void 
unlockvol(struct volume *vol)
{
    vol->flags &= ~VF_LOCKED;
    if ((vol->flags & VF_LOCKING) != 0) {
	vol->flags &= ~VF_LOCKING;
	wakeup(&vinum_conf.volume + vol->volno);
    }
}

/* Lock a plex, wait if it's in use */
int 
lockplex(struct plex *plex)
{
    int error;

    while ((plex->flags & VF_LOCKED) != 0) {
	plex->flags |= VF_LOCKING;
	/*
	 * It would seem to make more sense to sleep on
	 * the address 'plex'.  Unfortunately we can't
	 * guarantee that this address won't change due to
	 * table expansion.  The address we choose won't change.
	 */
	if ((error = tsleep(&vinum_conf.plex + plex->sdnos[0],
		    PRIBIO | PCATCH,
		    "plexlk",
		    0)) != 0)
	    return error;
    }
    plex->flags |= VF_LOCKED;
    return 0;
}

/* Unlock a plex and let the next one at it */
void 
unlockplex(struct plex *plex)
{
    plex->flags &= ~VF_LOCKED;
    if ((plex->flags & VF_LOCKING) != 0) {
	plex->flags &= ~VF_LOCKING;
	wakeup(&vinum_conf.plex + plex->plexno);
    }
}


/* Get a lock for the global config, wait if it's not available */
int 
lock_config(void)
{
    int error;

    while ((vinum_conf.flags & VF_LOCKED) != 0) {
	vinum_conf.flags |= VF_LOCKING;
	if ((error = tsleep(&vinum_conf, PRIBIO | PCATCH, "vincfg", 0)) != 0)
	    return error;
    }
    vinum_conf.flags |= VF_LOCKED;
    return 0;
}

/* Unlock and wake up any waiters  */
void 
unlock_config(void)
{
    vinum_conf.flags &= ~VF_LOCKED;
    if ((vinum_conf.flags & VF_LOCKING) != 0) {
	vinum_conf.flags &= ~VF_LOCKING;
	wakeup(&vinum_conf);
    }
}