lockres_or_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);
lockres->l_level = lockres->l_requested;
+
+ /*
+ * We set the OCFS2_LOCK_UPCONVERT_FINISHING flag before clearing
+ * the OCFS2_LOCK_BUSY flag to prevent the dc thread from
+ * downconverting the lock before the upconvert has fully completed.
+ */
+ lockres_or_flags(lockres, OCFS2_LOCK_UPCONVERT_FINISHING);
+
lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
mlog_exit_void();
assert_spin_locked(&lockres->l_lock);
- lockres_or_flags(lockres, OCFS2_LOCK_BLOCKED);
-
if (level > lockres->l_blocking) {
/* only schedule a downconvert if we haven't already scheduled
* one that goes low enough to satisfy the level we're
lockres->l_blocking = level;
}
+ if (needs_downconvert)
+ lockres_or_flags(lockres, OCFS2_LOCK_BLOCKED);
+
mlog_exit(needs_downconvert);
return needs_downconvert;
}
mlog_entry_void();
spin_lock_irqsave(&lockres->l_lock, flags);
lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
+ lockres_clear_flags(lockres, OCFS2_LOCK_UPCONVERT_FINISHING);
if (convert)
lockres->l_action = OCFS2_AST_INVALID;
else
again:
wait = 0;
+ spin_lock_irqsave(&lockres->l_lock, flags);
+
if (catch_signals && signal_pending(current)) {
ret = -ERESTARTSYS;
- goto out;
+ goto unlock;
}
- spin_lock_irqsave(&lockres->l_lock, flags);
-
mlog_bug_on_msg(lockres->l_flags & OCFS2_LOCK_FREEING,
"Cluster lock called on freeing lockres %s! flags "
"0x%lx\n", lockres->l_name, lockres->l_flags);
goto unlock;
}
+ if (lockres->l_flags & OCFS2_LOCK_UPCONVERT_FINISHING) {
+ /*
+ * We've upconverted. If the lock now has a level we can
+ * work with, we take it. If, however, the lock is not at the
+ * required level, we go thru the full cycle. One way this could
+ * happen is if a process requesting an upconvert to PR is
+ * closely followed by another requesting upconvert to an EX.
+ * If the process requesting EX lands here, we want it to
+ * continue attempting to upconvert and let the process
+ * requesting PR take the lock.
+ * If multiple processes request upconvert to PR, the first one
+ * here will take the lock. The others will have to go thru the
+ * OCFS2_LOCK_BLOCKED check to ensure that there is no pending
+ * downconvert request.
+ */
+ if (level <= lockres->l_level)
+ goto update_holders;
+ }
+
if (lockres->l_flags & OCFS2_LOCK_BLOCKED &&
!ocfs2_may_continue_on_blocked_lock(lockres, level)) {
/* is the lock is currently blocked on behalf of
goto again;
}
+update_holders:
/* Ok, if we get here then we're good to go. */
ocfs2_inc_holders(lockres, level);
ret = 0;
unlock:
+ lockres_clear_flags(lockres, OCFS2_LOCK_UPCONVERT_FINISHING);
+
spin_unlock_irqrestore(&lockres->l_lock, flags);
out:
/*
/* Mark the lockres as being dropped. It will no longer be
* queued if blocking, but we still may have to wait on it
* being dequeued from the downconvert thread before we can consider
- * it safe to drop.
+ * it safe to drop.
*
* You can *not* attempt to call cluster_lock on this lockres anymore. */
void ocfs2_mark_lockres_freeing(struct ocfs2_lock_res *lockres)
unsigned long flags;
int blocking;
int new_level;
+ int level;
int ret = 0;
int set_lvb = 0;
unsigned int gen;
spin_lock_irqsave(&lockres->l_lock, flags);
- BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BLOCKED));
-
recheck:
+ /*
+ * Is it still blocking? If not, we have no more work to do.
+ */
+ if (!(lockres->l_flags & OCFS2_LOCK_BLOCKED)) {
+ BUG_ON(lockres->l_blocking != DLM_LOCK_NL);
+ spin_unlock_irqrestore(&lockres->l_lock, flags);
+ ret = 0;
+ goto leave;
+ }
+
if (lockres->l_flags & OCFS2_LOCK_BUSY) {
/* XXX
* This is a *big* race. The OCFS2_LOCK_PENDING flag
goto leave;
}
+ /*
+ * This prevents livelocks. OCFS2_LOCK_UPCONVERT_FINISHING flag is
+ * set when the ast is received for an upconvert just before the
+ * OCFS2_LOCK_BUSY flag is cleared. Now if the fs received a bast
+ * on the heels of the ast, we want to delay the downconvert just
+ * enough to allow the up requestor to do its task. Because this
+ * lock is in the blocked queue, the lock will be downconverted
+ * as soon as the requestor is done with the lock.
+ */
+ if (lockres->l_flags & OCFS2_LOCK_UPCONVERT_FINISHING)
+ goto leave_requeue;
+
+ /*
+ * How can we block and yet be at NL? We were trying to upconvert
+ * from NL and got canceled. The code comes back here, and now
+ * we notice and clear BLOCKING.
+ */
+ if (lockres->l_level == DLM_LOCK_NL) {
+ BUG_ON(lockres->l_ex_holders || lockres->l_ro_holders);
+ lockres->l_blocking = DLM_LOCK_NL;
+ lockres_clear_flags(lockres, OCFS2_LOCK_BLOCKED);
+ spin_unlock_irqrestore(&lockres->l_lock, flags);
+ goto leave;
+ }
+
/* if we're blocking an exclusive and we have *any* holders,
* then requeue. */
if ((lockres->l_blocking == DLM_LOCK_EX)
* may sleep, so we save off a copy of what we're blocking as
* it may change while we're not holding the spin lock. */
blocking = lockres->l_blocking;
+ level = lockres->l_level;
spin_unlock_irqrestore(&lockres->l_lock, flags);
ctl->unblock_action = lockres->l_ops->downconvert_worker(lockres, blocking);
goto leave;
spin_lock_irqsave(&lockres->l_lock, flags);
- if (blocking != lockres->l_blocking) {
+ if ((blocking != lockres->l_blocking) || (level != lockres->l_level)) {
/* If this changed underneath us, then we can't drop
* it just yet. */
goto recheck;
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff