Commit c141ebda authored by Philipp Reisner's avatar Philipp Reisner
Browse files

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: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
parent ec0bddbc

drivers/block/drbd/drbd_int.h

+3 −6
Original line number Diff line number Diff line
@@ -169,11 +169,8 @@ drbd_insert_fault(struct drbd_conf *mdev, unsigned int type) { 
#define DRBD_MD_MAGIC (DRBD_MAGIC+4)



extern struct ratelimit_state drbd_ratelimit_state;

extern struct idr minors;

extern struct list_head drbd_tconns;

extern struct rw_semaphore drbd_cfg_rwsem;

/* drbd_cfg_rwsem protects: drbd_tconns list, minors idr, tconn->volumes idr 

   note: non sleeping iterations over the idrs are protoected by RCU */

extern struct idr minors; /* RCU, updates: genl_lock() */

extern struct list_head drbd_tconns; /* RCU, updates: genl_lock() */



/* on the wire */

enum drbd_packet {
@@ -1477,7 +1474,7 @@ extern struct page *drbd_alloc_pages(struct drbd_conf *, unsigned int, bool); 
extern void drbd_set_recv_tcq(struct drbd_conf *mdev, int tcq_enabled);

extern void _drbd_clear_done_ee(struct drbd_conf *mdev, struct list_head *to_be_freed);

extern void conn_flush_workqueue(struct drbd_tconn *tconn);

extern int drbd_connected(int vnr, void *p, void *data);

extern int drbd_connected(struct drbd_conf *mdev);

static inline void drbd_flush_workqueue(struct drbd_conf *mdev)

{

	conn_flush_workqueue(mdev->tconn);

drivers/block/drbd/drbd_main.c

+7 −13
Original line number Diff line number Diff line
@@ -120,7 +120,6 @@ module_param_string(usermode_helper, usermode_helper, sizeof(usermode_helper), 0 
 */

struct idr minors;

struct list_head drbd_tconns;  /* list of struct drbd_tconn */

DECLARE_RWSEM(drbd_cfg_rwsem);



struct kmem_cache *drbd_request_cache;

struct kmem_cache *drbd_ee_cache;	/* peer requests */
@@ -2331,21 +2330,20 @@ static void drbd_cleanup(void) 


	drbd_genl_unregister();



	down_write(&drbd_cfg_rwsem);

	idr_for_each_entry(&minors, mdev, i) {

		idr_remove(&minors, mdev_to_minor(mdev));

		idr_remove(&mdev->tconn->volumes, mdev->vnr);

		del_gendisk(mdev->vdisk);

		synchronize_rcu();

		/* synchronize_rcu(); No other threads running at this point */

		kref_put(&mdev->kref, &drbd_minor_destroy);

	}



	/* not _rcu since, no other updater anymore. Genl already unregistered */

	list_for_each_entry_safe(tconn, tmp, &drbd_tconns, all_tconn) {

		list_del_rcu(&tconn->all_tconn);

		synchronize_rcu();

		list_del(&tconn->all_tconn); /* not _rcu no proc, not other threads */

		/* synchronize_rcu(); */

		kref_put(&tconn->kref, &conn_destroy);

	}

	up_write(&drbd_cfg_rwsem);



	drbd_destroy_mempools();

	unregister_blkdev(DRBD_MAJOR, "drbd");
@@ -2408,7 +2406,7 @@ struct drbd_tconn *conn_get_by_name(const char *name) 
	if (!name || !name[0])

		return NULL;



	down_read(&drbd_cfg_rwsem);

	rcu_read_lock();

	list_for_each_entry_rcu(tconn, &drbd_tconns, all_tconn) {

		if (!strcmp(tconn->name, name)) {

			kref_get(&tconn->kref);
@@ -2417,7 +2415,7 @@ struct drbd_tconn *conn_get_by_name(const char *name) 
	}

	tconn = NULL;

found:

	up_read(&drbd_cfg_rwsem);

	rcu_read_unlock();

	return tconn;

}
@@ -2502,10 +2500,8 @@ struct drbd_tconn *conn_create(const char *name) 


	drbd_set_res_opts_defaults(&tconn->res_opts);



	down_write(&drbd_cfg_rwsem);

	kref_init(&tconn->kref);

	list_add_tail_rcu(&tconn->all_tconn, &drbd_tconns);

	up_write(&drbd_cfg_rwsem);



	return tconn;
@@ -2637,7 +2633,7 @@ enum drbd_ret_code conn_new_minor(struct drbd_tconn *tconn, unsigned int minor, 
	/* inherit the connection state */

	mdev->state.conn = tconn->cstate;

	if (mdev->state.conn == C_WF_REPORT_PARAMS)

		drbd_connected(vnr, mdev, tconn);

		drbd_connected(mdev);



	return NO_ERROR;
@@ -2913,12 +2909,10 @@ int drbd_md_read(struct drbd_conf *mdev, struct drbd_backing_dev *bdev) 
	}

	spin_unlock_irq(&mdev->tconn->req_lock);



	mutex_lock(&mdev->tconn->conf_update);

	/* This blocks wants to be get removed... */

	bdev->disk_conf->al_extents = be32_to_cpu(buffer->al_nr_extents);

	if (bdev->disk_conf->al_extents < DRBD_AL_EXTENTS_MIN)

		bdev->disk_conf->al_extents = DRBD_AL_EXTENTS_DEF;

	mutex_unlock(&mdev->tconn->conf_update);



 err:

	mutex_unlock(&mdev->md_io_mutex);

drivers/block/drbd/drbd_nl.c

+15 −28
Original line number Diff line number Diff line
@@ -335,10 +335,15 @@ static void conn_md_sync(struct drbd_tconn *tconn) 
	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 @@ int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info) 
		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 @@ int drbd_adm_connect(struct sk_buff *skb, struct genl_info *info) 
	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 @@ int get_one_status(struct sk_buff *skb, struct netlink_callback *cb) 
	 */



	/* 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 @@ int get_one_status(struct sk_buff *skb, struct netlink_callback *cb) 
        }



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 @@ int drbd_adm_add_minor(struct sk_buff *skb, struct genl_info *info) 
		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 @@ int drbd_adm_delete_minor(struct sk_buff *skb, struct genl_info *info) 
	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 @@ int drbd_adm_down(struct sk_buff *skb, struct genl_info *info) 
		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 @@ int drbd_adm_down(struct sk_buff *skb, struct genl_info *info) 
		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 @@ int drbd_adm_delete_connection(struct sk_buff *skb, struct genl_info *info) 
	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 @@ int drbd_adm_delete_connection(struct sk_buff *skb, struct genl_info *info) 
	} else {

		retcode = ERR_CONN_IN_USE;

	}

	up_write(&drbd_cfg_rwsem);



	if (retcode == NO_ERROR)

		drbd_thread_stop(&adm_ctx.tconn->worker);

drivers/block/drbd/drbd_proc.c

+2 −4
Original line number Diff line number Diff line
@@ -229,7 +229,7 @@ static int drbd_seq_show(struct seq_file *seq, void *v) 
	 oos .. known out-of-sync kB

	*/



	down_read(&drbd_cfg_rwsem);

	rcu_read_lock();

	idr_for_each_entry(&minors, mdev, i) {

		if (prev_i != i - 1)

			seq_printf(seq, "\n");
@@ -242,10 +242,8 @@ static int drbd_seq_show(struct seq_file *seq, void *v) 
		    mdev->state.role == R_SECONDARY) {

			seq_printf(seq, "%2d: cs:Unconfigured\n", i);

		} else {

			rcu_read_lock();

			nc = rcu_dereference(mdev->tconn->net_conf);

			wp = nc ? nc->wire_protocol - DRBD_PROT_A + 'A' : ' ';

			rcu_read_unlock();

			seq_printf(seq,

			   "%2d: cs:%s ro:%s/%s ds:%s/%s %c %c%c%c%c%c%c\n"

			   "    ns:%u nr:%u dw:%u dr:%u al:%u bm:%u "
@@ -299,7 +297,7 @@ static int drbd_seq_show(struct seq_file *seq, void *v) 
			}

		}

	}

	up_read(&drbd_cfg_rwsem);

	rcu_read_unlock();



	return 0;

}

drivers/block/drbd/drbd_receiver.c

+39 −22
Original line number Diff line number Diff line
@@ -63,7 +63,7 @@ enum finish_epoch { 


static int drbd_do_features(struct drbd_tconn *tconn);

static int drbd_do_auth(struct drbd_tconn *tconn);

static int drbd_disconnected(int vnr, void *p, void *data);

static int drbd_disconnected(struct drbd_conf *mdev);



static enum finish_epoch drbd_may_finish_epoch(struct drbd_conf *, struct drbd_epoch *, enum epoch_event);

static int e_end_block(struct drbd_work *, int);
@@ -811,9 +811,8 @@ static int drbd_socket_okay(struct socket **sock) 
}

/* Gets called if a connection is established, or if a new minor gets created

   in a connection */

int drbd_connected(int vnr, void *p, void *data)

int drbd_connected(struct drbd_conf *mdev)

{

	struct drbd_conf *mdev = (struct drbd_conf *)p;

	int err;



	atomic_set(&mdev->packet_seq, 0);
@@ -847,8 +846,9 @@ int drbd_connected(int vnr, void *p, void *data) 
static int conn_connect(struct drbd_tconn *tconn)

{

	struct socket *sock, *msock;

	struct drbd_conf *mdev;

	struct net_conf *nc;

	int timeout, try, h, ok;

	int vnr, timeout, try, h, ok;



	if (conn_request_state(tconn, NS(conn, C_WF_CONNECTION), CS_VERBOSE) < SS_SUCCESS)

		return -2;
@@ -1001,9 +1001,16 @@ static int conn_connect(struct drbd_tconn *tconn) 
	if (drbd_send_protocol(tconn) == -EOPNOTSUPP)

		return -1;



	down_read(&drbd_cfg_rwsem);

	h = !idr_for_each(&tconn->volumes, drbd_connected, tconn);

	up_read(&drbd_cfg_rwsem);

	rcu_read_lock();

	idr_for_each_entry(&tconn->volumes, mdev, vnr) {

		kref_get(&mdev->kref);

		rcu_read_unlock();

		drbd_connected(mdev);

		kref_put(&mdev->kref, &drbd_minor_destroy);

		rcu_read_lock();

	}

	rcu_read_unlock();



	return h;



out_release_sockets:
@@ -4242,8 +4249,9 @@ void conn_flush_workqueue(struct drbd_tconn *tconn) 


static void conn_disconnect(struct drbd_tconn *tconn)

{

	struct drbd_conf *mdev;

	enum drbd_conns oc;

	int rv = SS_UNKNOWN_ERROR;

	int vnr, rv = SS_UNKNOWN_ERROR;



	if (tconn->cstate == C_STANDALONE)

		return;
@@ -4252,9 +4260,16 @@ static void conn_disconnect(struct drbd_tconn *tconn) 
	drbd_thread_stop(&tconn->asender);

	drbd_free_sock(tconn);



	down_read(&drbd_cfg_rwsem);

	idr_for_each(&tconn->volumes, drbd_disconnected, tconn);

	up_read(&drbd_cfg_rwsem);

	rcu_read_lock();

	idr_for_each_entry(&tconn->volumes, mdev, vnr) {

		kref_get(&mdev->kref);

		rcu_read_unlock();

		drbd_disconnected(mdev);

		kref_put(&mdev->kref, &drbd_minor_destroy);

		rcu_read_lock();

	}

	rcu_read_unlock();



	conn_info(tconn, "Connection closed\n");



	if (conn_highest_role(tconn) == R_PRIMARY && conn_highest_pdsk(tconn) >= D_UNKNOWN)
@@ -4271,9 +4286,8 @@ static void conn_disconnect(struct drbd_tconn *tconn) 
		conn_request_state(tconn, NS(conn, C_STANDALONE), CS_VERBOSE | CS_HARD);

}



static int drbd_disconnected(int vnr, void *p, void *data)

static int drbd_disconnected(struct drbd_conf *mdev)

{

	struct drbd_conf *mdev = (struct drbd_conf *)p;

	enum drbd_fencing_p fp;

	unsigned int i;
@@ -4974,30 +4988,33 @@ static int got_skip(struct drbd_tconn *tconn, struct packet_info *pi) 
static int tconn_finish_peer_reqs(struct drbd_tconn *tconn)

{

	struct drbd_conf *mdev;

	int i, not_empty = 0;

	int vnr, not_empty = 0;



	do {

		clear_bit(SIGNAL_ASENDER, &tconn->flags);

		flush_signals(current);

		down_read(&drbd_cfg_rwsem);

		idr_for_each_entry(&tconn->volumes, mdev, i) {



		rcu_read_lock();

		idr_for_each_entry(&tconn->volumes, mdev, vnr) {

			kref_get(&mdev->kref);

			rcu_read_unlock();

			if (drbd_finish_peer_reqs(mdev)) {

				up_read(&drbd_cfg_rwsem);

				return 1; /* error */

				kref_put(&mdev->kref, &drbd_minor_destroy);

				return 1;

			}

			kref_put(&mdev->kref, &drbd_minor_destroy);

			rcu_read_lock();

		}

		up_read(&drbd_cfg_rwsem);

		set_bit(SIGNAL_ASENDER, &tconn->flags);



		spin_lock_irq(&tconn->req_lock);

		rcu_read_lock();

		idr_for_each_entry(&tconn->volumes, mdev, i) {

		idr_for_each_entry(&tconn->volumes, mdev, vnr) {

			not_empty = !list_empty(&mdev->done_ee);

			if (not_empty)

				break;

		}

		rcu_read_unlock();

		spin_unlock_irq(&tconn->req_lock);

		rcu_read_unlock();

	} while (not_empty);



	return 0;