From a2c97909f97ef32b76e856572fba4f77e1885fe6 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Thu, 6 Apr 2017 17:02:07 -0400 Subject: [PATCH] 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: Josef Bacik Signed-off-by: Jens Axboe --- drivers/block/nbd.c | 30 ++++++++++++++++++++++++++++++ include/uapi/linux/nbd.h | 6 +++++- 2 files changed, 35 insertions(+), 1 deletion(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 4237e7286e99..b78f23ce2395 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -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; } diff --git a/include/uapi/linux/nbd.h b/include/uapi/linux/nbd.h index c91c642ea900..155e33f81913 100644 --- a/include/uapi/linux/nbd.h +++ b/include/uapi/linux/nbd.h @@ -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 */