We want to be able to reconnect dead connections to existing block
devices, so add a reconfigure netlink command. We will also allow users
to change their timeout on the fly, but everything else will require a
disconnect and reconnect. You won't be able to add more connections
either, simply replace dead connections with new more lively
connections.
Signed-off-by: Josef Bacik <jbacik@xxxxxx>
---
drivers/block/nbd.c | 141 +++++++++++++++++++++++++++++++++++++++
include/uapi/linux/nbd-netlink.h | 1 +
2 files changed, 142 insertions(+)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index b8764e1..27958c3 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -785,6 +785,59 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
return 0;
}
+static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
+{
+ struct nbd_config *config = nbd->config;
+ struct socket *sock, *old;
+ struct recv_thread_args *args;
+ int i;
+ int err;
+
+ sock = sockfd_lookup(arg, &err);
+ if (!sock)
+ return err;
+
+ args = kzalloc(sizeof(*args), GFP_KERNEL);
+ if (!args) {
+ sockfd_put(sock);
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < config->num_connections; i++) {
+ struct nbd_sock *nsock = config->socks[i];
+
+ if (!nsock->dead)
+ continue;
+
+ mutex_lock(&nsock->tx_lock);
+ if (!nsock->dead) {
+ mutex_unlock(&nsock->tx_lock);
+ continue;
+ }
+ sk_set_memalloc(sock->sk);
+ atomic_inc(&config->recv_threads);
+ refcount_inc(&nbd->config_refs);
+ old = nsock->sock;
+ nsock->fallback_index = -1;
+ nsock->sock = sock;
+ nsock->dead = false;
+ INIT_WORK(&args->work, recv_work);
+ args->index = i;
+ args->nbd = nbd;
+ mutex_unlock(&nsock->tx_lock);
+ sockfd_put(old);
+
+ /* We take the tx_mutex in an error path in the recv_work, so we
+ * need to queue_work outside of the tx_mutex.
+ */
+ queue_work(recv_workqueue, &args->work);
+ return 0;
+ }
+ sockfd_put(sock);
+ kfree(args);
+ return -ENOSPC;
+}
+
/* Reset all properties of an NBD device */
static void nbd_reset(struct nbd_device *nbd)
{
@@ -1529,6 +1582,89 @@ static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
return 0;
}
+static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
+{
+ struct nbd_device *nbd = NULL;
+ struct nbd_config *config;
+ int index;
+ int ret = -EINVAL;
+
+ if (!netlink_capable(skb, CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (!info->attrs[NBD_ATTR_INDEX]) {
+ printk(KERN_ERR "nbd: must specify a device to reconfigure\n");
+ return -EINVAL;
+ }
+ index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
+ mutex_lock(&nbd_index_mutex);
+ nbd = idr_find(&nbd_index_idr, index);
+ mutex_unlock(&nbd_index_mutex);
+ if (!nbd) {
+ printk(KERN_ERR "nbd: couldn't find a device at index %d\n",
+ index);
+ return -EINVAL;
+ }
+
+ if (!refcount_inc_not_zero(&nbd->config_refs)) {
+ dev_err(nbd_to_dev(nbd),
+ "not configured, cannot reconfigure\n");
+ return -EINVAL;
+ }
+
+ mutex_lock(&nbd->config_lock);
+ config = nbd->config;
+ if (!test_bit(NBD_BOUND, &config->runtime_flags) ||
+ !nbd->task_recv) {
+ dev_err(nbd_to_dev(nbd),
+ "not configured, cannot reconfigure\n");
+ goto out;
+ }
+
+ if (info->attrs[NBD_ATTR_TIMEOUT]) {
+ u64 timeout = nla_get_u64(info->attrs[NBD_ATTR_TIMEOUT]);
+ nbd->tag_set.timeout = timeout * HZ;
+ blk_queue_rq_timeout(nbd->disk->queue, timeout * HZ);
+ }
+
+ if (info->attrs[NBD_ATTR_SOCKETS]) {
+ struct nlattr *attr;
+ int rem, fd;
+
+ nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
+ rem) {
+ struct nlattr *socks[NBD_SOCK_MAX+1];
+
+ if (nla_type(attr) != NBD_SOCK_ITEM) {
+ printk(KERN_ERR "nbd: socks must be embedded in a SOCK_ITEM attr\n");
+ ret = -EINVAL;
+ goto out;
+ }
+ ret = nla_parse_nested(socks, NBD_SOCK_MAX, attr,
+ nbd_sock_policy);
+ if (ret != 0) {
+ printk(KERN_ERR "nbd: error processing sock list\n");
+ ret = -EINVAL;
+ goto out;
+ }
+ if (!socks[NBD_SOCK_FD])
+ continue;
+ fd = (int)nla_get_u32(socks[NBD_SOCK_FD]);
+ ret = nbd_reconnect_socket(nbd, fd);
+ if (ret) {
+ if (ret == -ENOSPC)
+ ret = 0;
+ goto out;
+ }
+ dev_info(nbd_to_dev(nbd), "reconnected socket\n");
+ }
+ }
+out:
+ mutex_unlock(&nbd->config_lock);
+ nbd_config_put(nbd);
+ return ret;
+}
+
static const struct genl_ops nbd_connect_genl_ops[] = {
{
.cmd = NBD_CMD_CONNECT,
@@ -1540,6 +1676,11 @@ static const struct genl_ops nbd_connect_genl_ops[] = {
.policy = nbd_attr_policy,
.doit = nbd_genl_disconnect,
},
+ {
+ .cmd = NBD_CMD_RECONFIGURE,
+ .policy = nbd_attr_policy,
+ .doit = nbd_genl_reconfigure,
+ },
};
static struct genl_family nbd_genl_family __ro_after_init = {
diff --git a/include/uapi/linux/nbd-netlink.h b/include/uapi/linux/nbd-netlink.h
index fd0f4e4..f932f96 100644
--- a/include/uapi/linux/nbd-netlink.h
+++ b/include/uapi/linux/nbd-netlink.h
@@ -62,6 +62,7 @@ enum {
NBD_CMD_UNSPEC,
NBD_CMD_CONNECT,
NBD_CMD_DISCONNECT,
+ NBD_CMD_RECONFIGURE,
__NBD_CMD_MAX,
};
#define NBD_CMD_MAX (__NBD_CMD_MAX - 1)
--
2.7.4
