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 <jbacik@xxxxxx>
---
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 b33014a..d220045 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);
@@ -1540,6 +1543,7 @@ 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;
@@ -1634,6 +1638,15 @@ 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;
@@ -1671,6 +1684,8 @@ 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;
}
@@ -1723,6 +1738,7 @@ 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;
@@ -1774,6 +1790,18 @@ 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;
@@ -1811,6 +1839,8 @@ 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 c91c642..155e33f 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 */
--
2.7.4
