/*- * 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 1.10 1999/05/15 03:47:45 grog Exp grog $ */ #include #include /* * 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); } } /* 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. */ while (lock->stripe) { /* wait for it to become free */ #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 splx(s); tsleep((void *) lock->stripe, PRIBIO | PCATCH, "vrlock", 2 * hz); plex->lockwaits++; /* waited one more time */ s = splbio(); } break; /* out of the inner level loop */ } } 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); while (newlock < plex->alloclocks) plex->lock[newlock++].stripe = 0; } 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 | 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); } } /* Local Variables: */ /* fill-column: 50 */ /* End: */