drbd: debugfs: expose ed_data_gen_id

The effective data generation ID may be interesting for debugging
purposes of scenarios involving diskless states.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/block/drbd/drbd_debugfs.c

@@ -771,6 +771,13 @@ static int device_data_gen_id_show(struct seq_file *m, void *ignored)
 	return 0;
 }
 
+static int device_ed_gen_id_show(struct seq_file *m, void *ignored)
+{
+	struct drbd_device *device = m->private;
+	seq_printf(m, "0x%016llX\n", (unsigned long long)device->ed_uuid);
+	return 0;
+}
+
 #define drbd_debugfs_device_attr(name)						\
 static int device_ ## name ## _open(struct inode *inode, struct file *file)	\
 {										\
@@ -796,6 +803,7 @@ drbd_debugfs_device_attr(oldest_requests)
 drbd_debugfs_device_attr(act_log_extents)
 drbd_debugfs_device_attr(resync_extents)
 drbd_debugfs_device_attr(data_gen_id)
+drbd_debugfs_device_attr(ed_gen_id)
 
 void drbd_debugfs_device_add(struct drbd_device *device)
 {
@@ -839,6 +847,7 @@ void drbd_debugfs_device_add(struct drbd_device *device)
 	DCF(act_log_extents);
 	DCF(resync_extents);
 	DCF(data_gen_id);
+	DCF(ed_gen_id);
 #undef DCF
 	return;
 
@@ -854,6 +863,7 @@ void drbd_debugfs_device_cleanup(struct drbd_device *device)
 	drbd_debugfs_remove(&device->debugfs_vol_act_log_extents);
 	drbd_debugfs_remove(&device->debugfs_vol_resync_extents);
 	drbd_debugfs_remove(&device->debugfs_vol_data_gen_id);
+	drbd_debugfs_remove(&device->debugfs_vol_ed_gen_id);
 	drbd_debugfs_remove(&device->debugfs_vol);
 }
 

drivers/block/drbd/drbd_int.h

@@ -835,6 +835,7 @@ struct drbd_device {
 	struct dentry *debugfs_vol_act_log_extents;
 	struct dentry *debugfs_vol_resync_extents;
 	struct dentry *debugfs_vol_data_gen_id;
+	struct dentry *debugfs_vol_ed_gen_id;
 #endif
 
 	unsigned int vnr;	/* volume number within the connection */