Provide a mechanism to notify userspace that there's been a link problem
on a NBD device. This will allow userspace to re-establish a connection
and provide the new socket to the device without disrupting the device.
Signed-off-by: Josef Bacik <jbacik@xxxxxx>
---
drivers/block/nbd.c | 89 ++++++++++++++++++++++++++++++++++------
include/uapi/linux/nbd-netlink.h | 6 ++-
2 files changed, 81 insertions(+), 14 deletions(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 27958c3..911e36c 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -53,6 +53,7 @@ struct nbd_sock {
int sent;
bool dead;
int fallback_index;
+ int cookie;
};
struct recv_thread_args {
@@ -61,6 +62,11 @@ struct recv_thread_args {
int index;
};
+struct link_dead_args {
+ struct work_struct work;
+ int index;
+};
+
#define NBD_TIMEDOUT 0
#define NBD_DISCONNECT_REQUESTED 1
#define NBD_DISCONNECTED 2
@@ -100,6 +106,7 @@ struct nbd_device {
struct nbd_cmd {
struct nbd_device *nbd;
int index;
+ int cookie;
struct completion send_complete;
};
@@ -120,6 +127,7 @@ static int nbd_dev_dbg_init(struct nbd_device *nbd);
static void nbd_dev_dbg_close(struct nbd_device *nbd);
static void nbd_config_put(struct nbd_device *nbd);
static void nbd_connect_reply(struct genl_info *info, int index);
+static void nbd_dead_link_work(struct work_struct *work);
static inline struct device *nbd_to_dev(struct nbd_device *nbd)
{
@@ -152,8 +160,24 @@ static struct device_attribute pid_attr = {
.show = pid_show,
};
-static void nbd_mark_nsock_dead(struct nbd_sock *nsock)
+static int nbd_disconnected(struct nbd_config *config)
+{
+ return test_bit(NBD_DISCONNECTED, &config->runtime_flags) ||
+ test_bit(NBD_DISCONNECT_REQUESTED, &config->runtime_flags);
+}
+
+static void nbd_mark_nsock_dead(struct nbd_device *nbd, struct nbd_sock *nsock,
+ int notify)
{
+ if (!nsock->dead && notify && !nbd_disconnected(nbd->config)) {
+ struct link_dead_args *args;
+ args = kmalloc(sizeof(struct link_dead_args), GFP_NOIO);
+ if (args) {
+ INIT_WORK(&args->work, nbd_dead_link_work);
+ args->index = nbd->index;
+ queue_work(system_wq, &args->work);
+ }
+ }
if (!nsock->dead)
kernel_sock_shutdown(nsock->sock, SHUT_RDWR);
nsock->dead = true;
@@ -215,8 +239,7 @@ static void sock_shutdown(struct nbd_device *nbd)
for (i = 0; i < config->num_connections; i++) {
struct nbd_sock *nsock = config->socks[i];
mutex_lock(&nsock->tx_lock);
- kernel_sock_shutdown(nsock->sock, SHUT_RDWR);
- nbd_mark_nsock_dead(nsock);
+ nbd_mark_nsock_dead(nbd, nsock, 0);
mutex_unlock(&nsock->tx_lock);
}
dev_warn(disk_to_dev(nbd->disk), "shutting down sockets\n");
@@ -248,7 +271,14 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
struct nbd_sock *nsock =
config->socks[cmd->index];
mutex_lock(&nsock->tx_lock);
- nbd_mark_nsock_dead(nsock);
+ /* We can have multiple outstanding requests, so
+ * we don't want to mark the nsock dead if we've
+ * already reconnected with a new socket, so
+ * only mark it dead if its the same socket we
+ * were sent out on.
+ */
+ if (cmd->cookie == nsock->cookie)
+ nbd_mark_nsock_dead(nbd, nsock, 1);
mutex_unlock(&nsock->tx_lock);
}
blk_mq_requeue_request(req, true);
@@ -370,6 +400,7 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
iov_iter_advance(&from, sent);
}
cmd->index = index;
+ cmd->cookie = nsock->cookie;
request.type = htonl(type);
if (type != NBD_CMD_FLUSH) {
request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
@@ -458,12 +489,6 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
return 0;
}
-static int nbd_disconnected(struct nbd_config *config)
-{
- return test_bit(NBD_DISCONNECTED, &config->runtime_flags) ||
- test_bit(NBD_DISCONNECT_REQUESTED, &config->runtime_flags);
-}
-
/* NULL returned = something went wrong, inform userspace */
static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
{
@@ -564,7 +589,7 @@ static void recv_work(struct work_struct *work)
struct nbd_sock *nsock = config->socks[args->index];
mutex_lock(&nsock->tx_lock);
- nbd_mark_nsock_dead(nsock);
+ nbd_mark_nsock_dead(nbd, nsock, 1);
mutex_unlock(&nsock->tx_lock);
ret = PTR_ERR(cmd);
break;
@@ -691,7 +716,7 @@ static int nbd_handle_cmd(struct nbd_cmd *cmd, int index)
if (ret == -EAGAIN) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Request send failed trying another connection\n");
- nbd_mark_nsock_dead(nsock);
+ nbd_mark_nsock_dead(nbd, nsock, 1);
mutex_unlock(&nsock->tx_lock);
goto again;
}
@@ -780,6 +805,7 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
nsock->sock = sock;
nsock->pending = NULL;
nsock->sent = 0;
+ nsock->cookie = 0;
socks[config->num_connections++] = nsock;
return 0;
@@ -824,6 +850,7 @@ static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
INIT_WORK(&args->work, recv_work);
args->index = i;
args->nbd = nbd;
+ nsock->cookie++;
mutex_unlock(&nsock->tx_lock);
sockfd_put(old);
@@ -1683,6 +1710,10 @@ static const struct genl_ops nbd_connect_genl_ops[] = {
},
};
+static const struct genl_multicast_group nbd_mcast_grps[] = {
+ { .name = NBD_GENL_MCAST_GROUP_NAME, },
+};
+
static struct genl_family nbd_genl_family __ro_after_init = {
.hdrsize = 0,
.name = NBD_GENL_FAMILY_NAME,
@@ -1691,6 +1722,8 @@ static struct genl_family nbd_genl_family __ro_after_init = {
.ops = nbd_connect_genl_ops,
.n_ops = ARRAY_SIZE(nbd_connect_genl_ops),
.maxattr = NBD_ATTR_MAX,
+ .mcgrps = nbd_mcast_grps,
+ .n_mcgrps = ARRAY_SIZE(nbd_mcast_grps),
};
static void nbd_connect_reply(struct genl_info *info, int index)
@@ -1717,6 +1750,38 @@ static void nbd_connect_reply(struct genl_info *info, int index)
genlmsg_reply(skb, info);
}
+static void nbd_mcast_index(int index)
+{
+ struct sk_buff *skb;
+ void *msg_head;
+ int ret;
+
+ skb = genlmsg_new(nla_total_size(sizeof(u32)), GFP_KERNEL);
+ if (!skb)
+ return;
+ msg_head = genlmsg_put(skb, 0, 0, &nbd_genl_family, 0,
+ NBD_CMD_LINK_DEAD);
+ if (!msg_head) {
+ nlmsg_free(skb);
+ return;
+ }
+ ret = nla_put_u32(skb, NBD_ATTR_INDEX, index);
+ if (ret) {
+ nlmsg_free(skb);
+ return;
+ }
+ genlmsg_end(skb, msg_head);
+ genlmsg_multicast(&nbd_genl_family, skb, 0, 0, GFP_KERNEL);
+}
+
+static void nbd_dead_link_work(struct work_struct *work)
+{
+ struct link_dead_args *args = container_of(work, struct link_dead_args,
+ work);
+ nbd_mcast_index(args->index);
+ kfree(args);
+}
+
static int __init nbd_init(void)
{
int i;
diff --git a/include/uapi/linux/nbd-netlink.h b/include/uapi/linux/nbd-netlink.h
index f932f96..b69105cc 100644
--- a/include/uapi/linux/nbd-netlink.h
+++ b/include/uapi/linux/nbd-netlink.h
@@ -18,8 +18,9 @@
#ifndef _UAPILINUX_NBD_NETLINK_H
#define _UAPILINUX_NBD_NETLINK_H
-#define NBD_GENL_FAMILY_NAME "nbd"
-#define NBD_GENL_VERSION 0x1
+#define NBD_GENL_FAMILY_NAME "nbd"
+#define NBD_GENL_VERSION 0x1
+#define NBD_GENL_MCAST_GROUP_NAME "nbd_mc_group"
/* Configuration policy attributes, used for CONNECT */
enum {
@@ -63,6 +64,7 @@ enum {
NBD_CMD_CONNECT,
NBD_CMD_DISCONNECT,
NBD_CMD_RECONFIGURE,
+ NBD_CMD_LINK_DEAD,
__NBD_CMD_MAX,
};
#define NBD_CMD_MAX (__NBD_CMD_MAX - 1)
--
2.7.4
