[Cluster-devel] [PATCH 2/3] gfs2: Dequeue waiters when withdrawn

[Bob Peterson <rpeterso@redhat.com>]

When a withdraw occurs, ordinary (not system) glocks may not be granted
anymore. This patch takes measures to remove any pending waiters from
the glocks that will never be granted.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
---
 fs/gfs2/glock.c | 14 ++++++++++++++
 fs/gfs2/glock.h |  1 +
 fs/gfs2/util.c  |  5 +++++
 3 files changed, 20 insertions(+)

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index e540d1290099..0bfecffd71f1 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -2223,6 +2223,20 @@ static void dump_glock_func(struct gfs2_glock *gl)
 	dump_glock(NULL, gl, true);
 }
 
+static void withdraw_dq(struct gfs2_glock *gl)
+{
+	spin_lock(&gl->gl_lockref.lock);
+	if (!__lockref_is_dead(&gl->gl_lockref) &&
+	    glock_blocked_by_withdraw(gl))
+		do_error(gl, LM_OUT_ERROR); /* remove pending waiters */
+	spin_unlock(&gl->gl_lockref.lock);
+}
+
+void gfs2_gl_dq_holders(struct gfs2_sbd *sdp)
+{
+	glock_hash_walk(withdraw_dq, sdp);
+}
+
 /**
  * gfs2_gl_hash_clear - Empty out the glock hash table
  * @sdp: the filesystem
diff --git a/fs/gfs2/glock.h b/fs/gfs2/glock.h
index c0ae9100a0bc..d6fc449aa7ff 100644
--- a/fs/gfs2/glock.h
+++ b/fs/gfs2/glock.h
@@ -273,6 +273,7 @@ extern void gfs2_cancel_delete_work(struct gfs2_glock *gl);
 extern bool gfs2_delete_work_queued(const struct gfs2_glock *gl);
 extern void gfs2_flush_delete_work(struct gfs2_sbd *sdp);
 extern void gfs2_gl_hash_clear(struct gfs2_sbd *sdp);
+extern void gfs2_gl_dq_holders(struct gfs2_sbd *sdp);
 extern void gfs2_glock_finish_truncate(struct gfs2_inode *ip);
 extern void gfs2_glock_thaw(struct gfs2_sbd *sdp);
 extern void gfs2_glock_add_to_lru(struct gfs2_glock *gl);
diff --git a/fs/gfs2/util.c b/fs/gfs2/util.c
index 78cb12d0fba1..acf94c83b29b 100644
--- a/fs/gfs2/util.c
+++ b/fs/gfs2/util.c
@@ -164,6 +164,11 @@ static void signal_our_withdraw(struct gfs2_sbd *sdp)
 		}
 		if (!ret)
 			gfs2_make_fs_ro(sdp);
+		/*
+		 * Dequeue any pending non-system glock holders that can no
+		 * longer be granted because the file system is withdrawn.
+		 */
+		gfs2_gl_dq_holders(sdp);
 		gfs2_freeze_unlock(&freeze_gh);
 	}
 
-- 
2.36.1