[GFS2] Fix delayed demote race

There is a race in the delayed demote code where it does the wrong thing if a demotion to UN has occurred for other reasons before the delay has expired. This patch adds an assert to catch that condition as well as fixing the root cause by adding an additional check for the UN state. Signed-off-by: Steven Whitehouse <[email protected]> Cc: Bob Peterson <[email protected]>
beagleboard · Jul 7, 2008 · 265d529 · 265d529
1 parent f58ba88
commit 265d529
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
@@ -587,6 +587,7 @@ static void run_queue(struct gfs2_glock *gl, const int nonblock)
 		if (nonblock)
 			goto out_sched;
 		set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
+		GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
 		gl->gl_target = gl->gl_demote_state;
 	} else {
 		if (test_bit(GLF_DEMOTE, &gl->gl_flags))
@@ -617,7 +618,9 @@ static void glock_work_func(struct work_struct *work)
 	if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags))
 		finish_xmote(gl, gl->gl_reply);
 	spin_lock(&gl->gl_spin);
-	if (test_and_clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags)) {
+	if (test_and_clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
+	    gl->gl_state != LM_ST_UNLOCKED &&
+	    gl->gl_demote_state != LM_ST_EXCLUSIVE) {
 		unsigned long holdtime, now = jiffies;
 		holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
 		if (time_before(now, holdtime))