freebsd-dev/sys/dev/vinum/vinumlock.c
Greg Lehey 9702452a12 lockrange: Avoid a race condition which was causing random corruption,
panics and hangs in RAID-5 plexes, particularly with ata drives.

Original-code-by:   Bernd Walter <ticso@cicely.de>
Eagerly-awaited-by: sos
2000-05-04 07:37:11 +00:00

330 lines
9.3 KiB
C

/*-
* Copyright (c) 1997, 1998
* Nan Yang Computer Services Limited. All rights reserved.
*
* Parts copyright (c) 1997, 1998 Cybernet Corporation, NetMAX project.
*
* Written by Greg Lehey
*
* 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 1.12 2000/01/05 22:17:25 grog Exp grog $
* $FreeBSD$
*/
#include <dev/vinum/vinumhdr.h>
#include <dev/vinum/request.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,
"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,
"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,
"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);
}
}
/* Lock a stripe of a plex, wait if it's in use */
struct rangelock *
lockrange(daddr_t stripe, struct buf *bp, struct plex *plex)
{
int s;
struct rangelock *lock;
struct rangelock *pos; /* position of first free lock */
int foundlocks; /* number of locks found */
int newlock;
/*
* We could get by without counting the number
* of locks we find, but we have a linear search
* through a table which in most cases will be
* empty. It's faster to stop when we've found
* all the locks that are there. This is also
* the reason why we put pos at the beginning
* instead of the end, though it requires an
* extra test.
*/
pos = NULL;
foundlocks = 0;
/*
* we can't use 0 as a valid address, so
* increment all addresses by 1.
*/
stripe++;
/*
* We give the locks back from an interrupt
* context, so we need to raise the spl here.
*/
s = splbio();
/* Search the lock table for our stripe */
for (lock = plex->lock;
lock < &plex->lock[plex->alloclocks]
&& foundlocks < plex->usedlocks;
lock++) {
if (lock->stripe) { /* in use */
foundlocks++; /* found another one in use */
if ((lock->stripe == stripe) /* it's our stripe */
&&(lock->plexno == plex->plexno) /* and our plex */
&&(lock->bp != bp)) { /* but not our request */
/*
* It would be nice to sleep on the lock
* itself, but it could get moved if the
* table expands during the wait. Wait on
* the lock address + 1 (since waiting on
* 0 isn't allowed) instead. It isn't
* exactly unique, but we won't have many
* conflicts. The worst effect of a
* conflict would be an additional
* schedule and time through this loop.
*/
#ifdef VINUMDEBUG
if (debug & DEBUG_LASTREQS) {
struct rangelock info;
info.stripe = stripe;
info.bp = bp;
info.plexno = plex->plexno;
logrq(loginfo_lockwait, (union rqinfou) &info, bp);
}
#endif
plex->lockwaits++; /* waited one more time */
tsleep((void *) lock->stripe, PRIBIO, "vrlock", 2 * hz);
lock = plex->lock; /* start again */
foundlocks = 0;
pos = NULL;
}
} else if (pos == NULL) /* still looking for somewhere? */
pos = lock; /* a place to put this one */
}
/*
* The address range is free. Add our lock
* entry.
*/
if (pos == NULL) { /* Didn't find an entry */
if (foundlocks >= plex->alloclocks) { /* searched the lot, */
newlock = plex->alloclocks;
EXPAND(plex->lock, struct rangelock, plex->alloclocks, INITIAL_LOCKS);
pos = &plex->lock[newlock];
while (newlock < plex->alloclocks)
plex->lock[newlock++].stripe = 0;
} else
pos = lock; /* put it at the end */
}
pos->stripe = stripe;
pos->bp = bp;
pos->plexno = plex->plexno;
plex->usedlocks++; /* one more lock */
splx(s);
#ifdef VINUMDEBUG
if (debug & DEBUG_LASTREQS)
logrq(loginfo_lock, (union rqinfou) pos, bp);
#endif
return pos;
}
/* Unlock a volume and let the next one at it */
void
unlockrange(int plexno, struct rangelock *lock)
{
daddr_t lockaddr;
#ifdef VINUMDEBUG
if (debug & DEBUG_LASTREQS)
logrq(loginfo_unlock, (union rqinfou) lock, lock->bp);
#endif
lockaddr = lock->stripe;
lock->stripe = 0; /* no longer used */
PLEX[plexno].usedlocks--; /* one less lock */
wakeup((void *) lockaddr);
}
/* 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, "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);
}
}
/* Local Variables: */
/* fill-column: 50 */
/* End: */