GFS2: Fix race relating to glock min-hold time

In the case that a request for a glock arrives right after the
grant reply has arrived, it sometimes means that the gl_tstamp
field hasn't been updated recently enough. The net result is that
the min-hold time for the glock is ignored. If this happens
often enough, it leads to poor performance.

This patch adds an additional test, so that if the reply pending
bit is set on a glock, then it will select the maximum length of
time for the min-hold time, rather than looking at gl_tstamp.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 4cbb6957a0d4f3cd513e18583815d7e37cef7f91..806e1eb0aa0da0617f97af488f9d914cc931052e 100644 (file)
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1265,6 +1265,8 @@ static void blocking_cb(struct gfs2_sbd *sdp, struct lm_lockname *name,
        holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
        if (time_before(now, holdtime))
                delay = holdtime - now;
+       if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
+               delay = gl->gl_ops->go_min_hold_time;
 
        spin_lock(&gl->gl_spin);
        handle_callback(gl, state, 1, delay);