linux-kernel - [PATCH 22/29] GFS2: Ensure workqueue is scheduled after noexp request

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Message-Id: <1396343741-1524-23-git-send-email-swhiteho@redhat.com>
Date:	Tue,  1 Apr 2014 10:15:34 +0100
From:	Steven Whitehouse <swhiteho@...hat.com>
To:	linux-kernel@...r.kernel.org, cluster-devel@...hat.com
Cc:	Bob Peterson <rpeterso@...hat.com>,
	Steven Whitehouse <swhiteho@...hat.com>
Subject: [PATCH 22/29] GFS2: Ensure workqueue is scheduled after noexp request

From: Bob Peterson <rpeterso@...hat.com>

This patch closes a small timing window whereby a request to hold the
transaction glock can get stuck. The problem is that after the DLM has
granted the lock, it can get into a state whereby it doesn't transition
the glock to a held state, due to not having requeued the glock state
machine to finish the transition.

Signed-off-by: Bob Peterson <rpeterso@...hat.com>
Signed-off-by: Steven Whitehouse <swhiteho@...hat.com>

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 52f7478..aec7f73 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1047,9 +1047,13 @@ int gfs2_glock_nq(struct gfs2_holder *gh)
 
 	spin_lock(&gl->gl_spin);
 	add_to_queue(gh);
-	if ((LM_FLAG_NOEXP & gh->gh_flags) &&
-	    test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
+	if (unlikely((LM_FLAG_NOEXP & gh->gh_flags) &&
+		     test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))) {
 		set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
+		gl->gl_lockref.count++;
+		if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
+			gl->gl_lockref.count--;
+	}
 	run_queue(gl, 1);
 	spin_unlock(&gl->gl_spin);
 
-- 
1.8.3.1

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