[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 <swhiteho@redhat.com>
Cc: Bob Peterson <rpeterso@redhat.com>
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 8d5450f..cd0aa21 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -587,6 +587,7 @@
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 @@
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))