From 799f9a38bc9f5551819fd118a82826df0a8525cf Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Thu, 6 Apr 2017 17:02:02 -0400 Subject: [PATCH] nbd: multicast dead link notifications 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 Signed-off-by: Jens Axboe --- 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 394ea891d909..b55cc057f569 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 @@ out: 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 @@ again: 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); @@ -1682,6 +1709,10 @@ 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, @@ -1690,6 +1721,8 @@ 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) @@ -1716,6 +1749,38 @@ 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 f932f96a7c2f..b69105cc8eea 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)