drbd: Removing drbd_cfg_rwsem
* Updates to all configuration items is done under genl_lock().
Including removal of mdevs or tconns.
* All read non sleeping read sides are protected by rcu
* All sleeping read sides keep reference counts to keep the
objects alive
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index a0cf000..72ce3b0 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -335,10 +335,15 @@
struct drbd_conf *mdev;
int vnr;
- down_read(&drbd_cfg_rwsem);
- idr_for_each_entry(&tconn->volumes, mdev, vnr)
+ rcu_read_lock();
+ idr_for_each_entry(&tconn->volumes, mdev, vnr) {
+ kref_get(&mdev->kref);
+ rcu_read_unlock();
drbd_md_sync(mdev);
- up_read(&drbd_cfg_rwsem);
+ kref_put(&mdev->kref, &drbd_minor_destroy);
+ rcu_read_lock();
+ }
+ rcu_read_unlock();
}
int conn_khelper(struct drbd_tconn *tconn, char *cmd)
@@ -1193,12 +1198,12 @@
rcu_assign_pointer(mdev->rs_plan_s, new_plan);
}
+ mutex_unlock(&mdev->tconn->conf_update);
drbd_md_sync(mdev);
if (mdev->state.conn >= C_CONNECTED)
drbd_send_sync_param(mdev);
- mutex_unlock(&mdev->tconn->conf_update);
synchronize_rcu();
kfree(old_disk_conf);
kfree(old_plan);
@@ -2013,7 +2018,7 @@
new_my_addr = (struct sockaddr *)&new_conf->my_addr;
new_peer_addr = (struct sockaddr *)&new_conf->peer_addr;
- /* No need to take drbd_cfg_rwsem here. All reconfiguration is
+ /* No need for _rcu here. All reconfiguration is
* strictly serialized on genl_lock(). We are protected against
* concurrent reconfiguration/addition/deletion */
list_for_each_entry(oconn, &drbd_tconns, all_tconn) {
@@ -2672,7 +2677,7 @@
*/
/* synchronize with conn_create()/conn_destroy() */
- down_read(&drbd_cfg_rwsem);
+ rcu_read_lock();
/* revalidate iterator position */
list_for_each_entry_rcu(tmp, &drbd_tconns, all_tconn) {
if (pos == NULL) {
@@ -2738,7 +2743,7 @@
}
out:
- up_read(&drbd_cfg_rwsem);
+ rcu_read_unlock();
/* where to start the next iteration */
cb->args[0] = (long)pos;
cb->args[1] = (pos == tconn) ? volume + 1 : 0;
@@ -3018,9 +3023,7 @@
goto out;
}
- down_write(&drbd_cfg_rwsem);
retcode = conn_new_minor(adm_ctx.tconn, dh->minor, adm_ctx.volume);
- up_write(&drbd_cfg_rwsem);
out:
drbd_adm_finish(info, retcode);
return 0;
@@ -3053,9 +3056,7 @@
if (retcode != NO_ERROR)
goto out;
- down_write(&drbd_cfg_rwsem);
retcode = adm_delete_minor(adm_ctx.mdev);
- up_write(&drbd_cfg_rwsem);
out:
drbd_adm_finish(info, retcode);
return 0;
@@ -3078,52 +3079,43 @@
goto out;
}
- down_read(&drbd_cfg_rwsem);
/* demote */
idr_for_each_entry(&adm_ctx.tconn->volumes, mdev, i) {
retcode = drbd_set_role(mdev, R_SECONDARY, 0);
if (retcode < SS_SUCCESS) {
drbd_msg_put_info("failed to demote");
- goto out_unlock;
+ goto out;
}
}
- up_read(&drbd_cfg_rwsem);
- /* disconnect; may stop the receiver;
- * must not hold the drbd_cfg_rwsem */
retcode = conn_try_disconnect(adm_ctx.tconn, 0);
if (retcode < SS_SUCCESS) {
drbd_msg_put_info("failed to disconnect");
goto out;
}
- down_read(&drbd_cfg_rwsem);
/* detach */
idr_for_each_entry(&adm_ctx.tconn->volumes, mdev, i) {
retcode = adm_detach(mdev);
if (retcode < SS_SUCCESS) {
drbd_msg_put_info("failed to detach");
- goto out_unlock;
+ goto out;
}
}
- up_read(&drbd_cfg_rwsem);
/* If we reach this, all volumes (of this tconn) are Secondary,
* Disconnected, Diskless, aka Unconfigured. Make sure all threads have
- * actually stopped, state handling only does drbd_thread_stop_nowait().
- * This needs to be done without holding drbd_cfg_rwsem. */
+ * actually stopped, state handling only does drbd_thread_stop_nowait(). */
drbd_thread_stop(&adm_ctx.tconn->worker);
/* Now, nothing can fail anymore */
/* delete volumes */
- down_write(&drbd_cfg_rwsem);
idr_for_each_entry(&adm_ctx.tconn->volumes, mdev, i) {
retcode = adm_delete_minor(mdev);
if (retcode != NO_ERROR) {
/* "can not happen" */
drbd_msg_put_info("failed to delete volume");
- up_write(&drbd_cfg_rwsem);
goto out;
}
}
@@ -3140,10 +3132,7 @@
retcode = ERR_CONN_IN_USE;
drbd_msg_put_info("failed to delete connection");
}
- up_write(&drbd_cfg_rwsem);
goto out;
-out_unlock:
- up_read(&drbd_cfg_rwsem);
out:
drbd_adm_finish(info, retcode);
return 0;
@@ -3159,7 +3148,6 @@
if (retcode != NO_ERROR)
goto out;
- down_write(&drbd_cfg_rwsem);
if (conn_lowest_minor(adm_ctx.tconn) < 0) {
list_del_rcu(&adm_ctx.tconn->all_tconn);
synchronize_rcu();
@@ -3169,7 +3157,6 @@
} else {
retcode = ERR_CONN_IN_USE;
}
- up_write(&drbd_cfg_rwsem);
if (retcode == NO_ERROR)
drbd_thread_stop(&adm_ctx.tconn->worker);
