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Commit a2c97909 authored by Josef Bacik's avatar Josef Bacik Committed by Jens Axboe
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nbd: add a flag to destroy an nbd device on disconnect 



For ease of management it would be nice for users to specify that the
device node for a nbd device is destroyed once it is disconnected and
there are no more users.  Add a client flag and enable this operation to
happen.

Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent c6a4759e

drivers/block/nbd.c

+30 −0
Original line number Diff line number Diff line
@@ -74,6 +74,7 @@ struct link_dead_args { 
#define NBD_HAS_PID_FILE		3

#define NBD_HAS_CONFIG_REF		4

#define NBD_BOUND			5

#define NBD_DESTROY_ON_DISCONNECT	6



struct nbd_config {

	u32 flags;
@@ -174,6 +175,7 @@ static void nbd_dev_remove(struct nbd_device *nbd) 
		del_gendisk(disk);

		blk_cleanup_queue(disk->queue);

		blk_mq_free_tag_set(&nbd->tag_set);

		disk->private_data = NULL;

		put_disk(disk);

	}

	kfree(nbd);
@@ -1028,6 +1030,7 @@ static void nbd_config_put(struct nbd_device *nbd) 
			kfree(config->socks);

		}

		nbd_reset(nbd);



		mutex_unlock(&nbd->config_lock);

		nbd_put(nbd);

		module_put(THIS_MODULE);
@@ -1539,6 +1542,7 @@ static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info) 
	struct nbd_config *config;

	int index = -1;

	int ret;

	bool put_dev = false;



	if (!netlink_capable(skb, CAP_SYS_ADMIN))

		return -EPERM;
@@ -1633,6 +1637,15 @@ static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info) 
	if (info->attrs[NBD_ATTR_SERVER_FLAGS])

		config->flags =

			nla_get_u64(info->attrs[NBD_ATTR_SERVER_FLAGS]);

	if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {

		u64 flags = nla_get_u64(info->attrs[NBD_ATTR_CLIENT_FLAGS]);

		if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {

			set_bit(NBD_DESTROY_ON_DISCONNECT,

				&config->runtime_flags);

			put_dev = true;

		}

	}



	if (info->attrs[NBD_ATTR_SOCKETS]) {

		struct nlattr *attr;

		int rem, fd;
@@ -1670,6 +1683,8 @@ static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info) 
		nbd_connect_reply(info, nbd->index);

	}

	nbd_config_put(nbd);

	if (put_dev)

		nbd_put(nbd);

	return ret;

}
@@ -1722,6 +1737,7 @@ static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info) 
	struct nbd_config *config;

	int index;

	int ret = -EINVAL;

	bool put_dev = false;



	if (!netlink_capable(skb, CAP_SYS_ADMIN))

		return -EPERM;
@@ -1773,6 +1789,18 @@ static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info) 
			nla_get_u64(info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);

		config->dead_conn_timeout *= HZ;

	}

	if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {

		u64 flags = nla_get_u64(info->attrs[NBD_ATTR_CLIENT_FLAGS]);

		if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {

			if (!test_and_set_bit(NBD_DESTROY_ON_DISCONNECT,

					      &config->runtime_flags))

				put_dev = true;

		} else {

			if (test_and_clear_bit(NBD_DESTROY_ON_DISCONNECT,

					       &config->runtime_flags))

				refcount_inc(&nbd->refs);

		}

	}



	if (info->attrs[NBD_ATTR_SOCKETS]) {

		struct nlattr *attr;
@@ -1810,6 +1838,8 @@ static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info) 
	mutex_unlock(&nbd->config_lock);

	nbd_config_put(nbd);

	nbd_put(nbd);

	if (put_dev)

		nbd_put(nbd);

	return ret;

}

include/uapi/linux/nbd.h

+5 −1
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ enum { 
	NBD_CMD_TRIM = 4

};



/* values for flags field */

/* values for flags field, these are server interaction specific. */

#define NBD_FLAG_HAS_FLAGS	(1 << 0) /* nbd-server supports flags */

#define NBD_FLAG_READ_ONLY	(1 << 1) /* device is read-only */

#define NBD_FLAG_SEND_FLUSH	(1 << 2) /* can flush writeback cache */
@@ -45,6 +45,10 @@ enum { 
#define NBD_FLAG_SEND_TRIM	(1 << 5) /* send trim/discard */

#define NBD_FLAG_CAN_MULTI_CONN	(1 << 8)	/* Server supports multiple connections per export. */



/* These are client behavior specific flags. */

#define NBD_CFLAG_DESTROY_ON_DISCONNECT	(1 << 0) /* delete the nbd device on

						    disconnect. */



/* userspace doesn't need the nbd_device structure */



/* These are sent over the network in the request/reply magic fields */