nbd: add a reconfigure netlink command

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@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index efd2eba37c695b5d8535c8feb3454c60c0354c99..394ea891d9094f1c7b171edf918a83a0af9aec8a 100644 (file)
--- 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)
 {
@@ -1528,6 +1581,89 @@ 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,
@@ -1539,6 +1675,11 @@ 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 fd0f4e45f03eea02421e74d33a71b29fa2c713f6..f932f96a7c2f1415a9c00ee5fa8aae38a7df070c 100644 (file)
--- 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)