-
-/*
- * This variable controls the maximum number of processes that will
- * be checked in doing deadlock detection.
- */
-int maxlockdepth = MAXDEPTH;
-
-/*
- * Set a byte-range lock.
- */
-ufs_setlock(lock)
- register struct lockf *lock;
-{
- register struct inode *ip = lock->lf_inode;
- register struct lockf *block;
- static char lockstr[] = "lockf";
- int priority, error;
-
-#ifdef LOCKF_DEBUG
- if (lockf_debug & 4)
- lf_print("ufs_setlock", lock);
-#endif /* LOCKF_DEBUG */
-
- /*
- * Set the priority
- */
- priority = PLOCK;
- if ((lock->lf_type & F_WRLCK) == 0)
- priority += 4;
- priority |= PCATCH;
- /*
- * Scan lock list for this file looking for locks that would block us.
- */
- while (block = lf_getblock(lock)) {
- /*
- * Free the structure and return if nonblocking.
- */
- if ((lock->lf_flags & F_WAIT) == 0) {
- free(lock, M_LOCKF);
- return (EAGAIN);
- }
- /*
- * We are blocked. Since flock style locks cover
- * the whole file, there is no chance for deadlock.
- * For byte-range locks we must check for deadlock.
- *
- * Deadlock detection is done by looking through the
- * wait channels to see if there are any cycles that
- * involve us. MAXDEPTH is set just to make sure we
- * do not go off into neverland.
- */
- if ((lock->lf_flags & F_POSIX) &&
- (block->lf_flags & F_POSIX)) {
- register struct proc *wproc;
- register struct lockf *waitblock;
- int i = 0;
-
- /* The block is waiting on something */
- wproc = (struct proc *)block->lf_id;
- while (wproc->p_wchan &&
- (wproc->p_wmesg == lockstr) &&
- (i++ < maxlockdepth)) {
- waitblock = (struct lockf *)wproc->p_wchan;
- /* Get the owner of the blocking lock */
- waitblock = waitblock->lf_next;
- if ((waitblock->lf_flags & F_POSIX) == 0)
- break;
- wproc = (struct proc *)waitblock->lf_id;
- if (wproc == (struct proc *)lock->lf_id) {
- free(lock, M_LOCKF);
- return (EDEADLK);
- }
- }
- }
- /*
- * Add our lock to the blocked
- * list and sleep until we're free.
- */
-#ifdef LOCKF_DEBUG
- if (lockf_debug & 4)
- lf_print("ufs_advlock: blocking on", block);
-#endif /* LOCKF_DEBUG */
- /*
- * Remember who blocked us (for deadlock detection)
- */
- lock->lf_next = block;
- lf_addblock(block, lock);
- if (error = tsleep((caddr_t *)lock, priority, lockstr, 0)) {
- free(lock, M_LOCKF);
- return (error);
- }
- }
- /*
- * No blocks!! Add the lock. Note that addlock will
- * downgrade or upgrade any overlapping locks this
- * process already owns.
- */
-#ifdef LOCKF_DEBUG
- if (lockf_debug & 4)
- lf_print("ufs_advlock: got the lock", lock);
-#endif /* LOCKF_DEBUG */
- lf_addlock(lock);
- return (0);
-}
-
-/*
- * Remove a byte-range lock on an inode.
- */
-ufs_advunlock(lock)
- struct lockf *lock;
-{
- struct lockf *blocklist;
-
- if (lock->lf_inode->i_lockf == (struct lockf *)0)
- return (0);
-#ifdef LOCKF_DEBUG
- if (lockf_debug & 4)
- lf_print("ufs_advunlock", lock);
-#endif /* LOCKF_DEBUG */
- /*
- * Generally, find the lock (or an overlap to that lock)
- * and remove it (or shrink it), then wakeup anyone we can.
- */
- blocklist = lf_remove(lock);
- FREE(lock, M_LOCKF);
- lf_wakelock(blocklist);
- return (0);
-}
-
-/*
- * Return the blocking pid
- */
-ufs_advgetlock(lock, fl)
- register struct lockf *lock;
- register struct flock *fl;
-{
- register struct lockf *block;
- off_t start, end;
-
-#ifdef LOCKF_DEBUG
- if (lockf_debug & 4)
- lf_print("ufs_advgetlock", lock);
-#endif /* LOCKF_DEBUG */
-
- if (block = lf_getblock(lock)) {
- fl->l_type = block->lf_type;
- fl->l_whence = SEEK_SET;
- fl->l_start = block->lf_start;
- if (block->lf_end == -1)
- fl->l_len = 0;
- else
- fl->l_len = block->lf_end - block->lf_start;
- if (block->lf_flags & F_POSIX)
- fl->l_pid = ((struct proc *)(block->lf_id))->p_pid;
- else
- fl->l_pid = -1;
- }
- FREE(lock, M_LOCKF);
- return (0);
-}
projects / unix-history / blobdiff