cifs: release leases for deferred close handles when freezing

We should not be caching closed files when freeze is invoked on an fs
(so we can release resources more gracefully).

Fixes xfstests generic/068 generic/390 generic/491

Reviewed-by: David Howells <dhowells@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: Steve French

fs/cifs/cifsfs.c

@@ -760,6 +760,20 @@ static void cifs_umount_begin(struct super_block *sb)
 	return;
 }
 
+static int cifs_freeze(struct super_block *sb)
+{
+	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
+	struct cifs_tcon *tcon;
+
+	if (cifs_sb == NULL)
+		return 0;
+
+	tcon = cifs_sb_master_tcon(cifs_sb);
+
+	cifs_close_all_deferred_files(tcon);
+	return 0;
+}
+
 #ifdef CONFIG_CIFS_STATS2
 static int cifs_show_stats(struct seq_file *s, struct dentry *root)
 {
@@ -798,6 +812,7 @@ static const struct super_operations cifs_super_ops = {
 	as opens */
 	.show_options = cifs_show_options,
 	.umount_begin   = cifs_umount_begin,
+	.freeze_fs      = cifs_freeze,
 #ifdef CONFIG_CIFS_STATS2
 	.show_stats = cifs_show_stats,
 #endif