1 files changed, 19 insertions, 33 deletions

diff --git a/fs/gfs2/glops.c b/fs/gfs2/glops.c
index 01d433ed6ce7..7c48c7afd6a4 100644
--- a/fs/gfs2/glops.c
+++ b/fs/gfs2/glops.c
@@ -561,47 +561,33 @@ static void inode_go_dump(struct seq_file *seq, struct gfs2_glock *gl,
 }
 
 /**
- * freeze_go_sync - promote/demote the freeze glock
+ * freeze_go_callback - A cluster node is requesting a freeze
  * @gl: the glock
+ * @remote: true if this came from a different cluster node
  */
 
-static int freeze_go_sync(struct gfs2_glock *gl)
+static void freeze_go_callback(struct gfs2_glock *gl, bool remote)
 {
-	int error = 0;
 	struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
+	struct super_block *sb = sdp->sd_vfs;
+
+	if (!remote ||
+	    gl->gl_state != LM_ST_SHARED ||
+	    gl->gl_demote_state != LM_ST_UNLOCKED)
+		return;
 
 	/*
-	 * We need to check gl_state == LM_ST_SHARED here and not gl_req ==
-	 * LM_ST_EXCLUSIVE. That's because when any node does a freeze,
-	 * all the nodes should have the freeze glock in SH mode and they all
-	 * call do_xmote: One for EX and the others for UN. They ALL must
-	 * freeze locally, and they ALL must queue freeze work. The freeze_work
-	 * calls freeze_func, which tries to reacquire the freeze glock in SH,
-	 * effectively waiting for the thaw on the node who holds it in EX.
-	 * Once thawed, the work func acquires the freeze glock in
-	 * SH and everybody goes back to thawed.
+	 * Try to get an active super block reference to prevent racing with
+	 * unmount (see trylock_super()).  But note that unmount isn't the only
+	 * place where a write lock on s_umount is taken, and we can fail here
+	 * because of things like remount as well.
 	 */
-	if (gl->gl_state == LM_ST_SHARED && !gfs2_withdrawn(sdp) &&
-	    !test_bit(SDF_NORECOVERY, &sdp->sd_flags)) {
-		atomic_set(&sdp->sd_freeze_state, SFS_STARTING_FREEZE);
-		error = freeze_super(sdp->sd_vfs);
-		if (error) {
-			fs_info(sdp, "GFS2: couldn't freeze filesystem: %d\n",
-				error);
-			if (gfs2_withdrawn(sdp)) {
-				atomic_set(&sdp->sd_freeze_state, SFS_UNFROZEN);
-				return 0;
-			}
-			gfs2_assert_withdraw(sdp, 0);
-		}
-		queue_work(gfs2_freeze_wq, &sdp->sd_freeze_work);
-		if (test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))
-			gfs2_log_flush(sdp, NULL, GFS2_LOG_HEAD_FLUSH_FREEZE |
-				       GFS2_LFC_FREEZE_GO_SYNC);
-		else /* read-only mounts */
-			atomic_set(&sdp->sd_freeze_state, SFS_FROZEN);
+	if (down_read_trylock(&sb->s_umount)) {
+		atomic_inc(&sb->s_active);
+		up_read(&sb->s_umount);
+		if (!queue_work(gfs2_freeze_wq, &sdp->sd_freeze_work))
+			deactivate_super(sb);
 	}
-	return 0;
 }
 
 /**
@@ -761,9 +747,9 @@ const struct gfs2_glock_operations gfs2_rgrp_glops = {
 };
 
 const struct gfs2_glock_operations gfs2_freeze_glops = {
-	.go_sync = freeze_go_sync,
 	.go_xmote_bh = freeze_go_xmote_bh,
 	.go_demote_ok = freeze_go_demote_ok,
+	.go_callback = freeze_go_callback,
 	.go_type = LM_TYPE_NONDISK,
 	.go_flags = GLOF_NONDISK,
 };