freebsd-dev/sys/dev/vinum/vinumlock.c
Greg Lehey d026346c86 Change the way the plex lock mutexes work. Previously they were part
of the struct plex, which tore apart the mutex linked lists when the
plex table was expanded.  Now we maintain a pool of mutexes (currently
32) to be shared by all plexes.  This is still a lot better than the
splhigh() method used in other architectures.

Approved by: re (jhb)
2003-05-23 01:14:35 +00:00

265 lines
8.0 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 1.19 2003/05/23 01:07:18 grog Exp $
* $FreeBSD$
*/
#include <dev/vinum/vinumhdr.h>
#include <dev/vinum/request.h>
/* Lock a drive, wait if it's in use */
#ifdef 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 stripe of a plex, wait if it's in use */
struct rangelock *
lockrange(daddr_t stripe, struct buf *bp, struct plex *plex)
{
struct rangelock *lock;
struct rangelock *pos; /* position of first free lock */
int foundlocks; /* number of locks found */
/*
* 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++;
mtx_lock(plex->lockmtx);
/* Wait here if the table is full */
while (plex->usedlocks == PLEX_LOCKS) /* all in use */
msleep(&plex->usedlocks, plex->lockmtx, PRIBIO, "vlock", 0);
#ifdef DIAGNOSTIC
if (plex->usedlocks >= PLEX_LOCKS)
panic("lockrange: Too many locks in use");
#endif
lock = plex->lock; /* pointer in lock table */
if (plex->usedlocks > 0) /* something locked, */
/* Search the lock table for our stripe */
for (; lock < &plex->lock[PLEX_LOCKS]
&& foundlocks < plex->usedlocks;
lock++) {
if (lock->stripe) { /* in use */
foundlocks++; /* found another one in use */
if ((lock->stripe == stripe) /* it's our stripe */
&&(lock->bp != bp)) { /* but not our request */
#ifdef VINUMDEBUG
if (debug & DEBUG_LOCKREQS) {
struct rangelockinfo lockinfo;
lockinfo.stripe = stripe;
lockinfo.bp = bp;
lockinfo.plexno = plex->plexno;
logrq(loginfo_lockwait, (union rqinfou) &lockinfo, bp);
}
#endif
plex->lockwaits++; /* waited one more time */
msleep(lock, plex->lockmtx, PRIBIO, "vrlock", 0);
lock = &plex->lock[-1]; /* start again */
foundlocks = 0;
pos = NULL;
}
} else if (pos == NULL) /* still looking for somewhere? */
pos = lock; /* a place to put this one */
}
/*
* This untidy looking code ensures that we'll
* always end up pointing to the first free lock
* entry, thus minimizing the number of
* iterations necessary.
*/
if (pos == NULL) /* didn't find one on the way, */
pos = lock; /* use the one we're pointing to */
/*
* The address range is free, and we're pointing
* to the first unused entry. Make it ours.
*/
pos->stripe = stripe;
pos->bp = bp;
plex->usedlocks++; /* one more lock */
mtx_unlock(plex->lockmtx);
#ifdef VINUMDEBUG
if (debug & DEBUG_LOCKREQS) {
struct rangelockinfo lockinfo;
lockinfo.stripe = stripe;
lockinfo.bp = bp;
lockinfo.plexno = plex->plexno;
logrq(loginfo_lock, (union rqinfou) &lockinfo, bp);
}
#endif
return pos;
}
/* Unlock a volume and let the next one at it */
void
unlockrange(int plexno, struct rangelock *lock)
{
struct plex *plex;
plex = &PLEX[plexno];
#ifdef DIAGNOSTIC
if (lock < &plex->lock[0] || lock >= &plex->lock[PLEX_LOCKS])
panic("vinum: rangelock %p on plex %d invalid, not between %p and %p",
lock,
plexno,
&plex->lock[0],
&plex->lock[PLEX_LOCKS]);
#endif
#ifdef VINUMDEBUG
if (debug & DEBUG_LOCKREQS) {
struct rangelockinfo lockinfo;
lockinfo.stripe = lock->stripe;
lockinfo.bp = lock->bp;
lockinfo.plexno = plex->plexno;
logrq(loginfo_lockwait, (union rqinfou) &lockinfo, lock->bp);
}
#endif
lock->stripe = 0; /* no longer used */
plex->usedlocks--; /* one less lock */
if (plex->usedlocks == PLEX_LOCKS - 1) /* we were full, */
wakeup(&plex->usedlocks); /* get a waiter if one's there */
wakeup((void *) lock);
}
/* 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 global config 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: */