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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 <jbacik@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Josef Bacik 2017-04-06 17:02:07 -04:00 committed by Jens Axboe
parent c6a4759ea0
commit a2c97909f9
2 changed files with 35 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
drivers/block/nbd.c
View File

@ -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 @@ again:
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 @@ out:
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 @@ out:
mutex_unlock(&nbd->config_lock);
nbd_config_put(nbd);
nbd_put(nbd);
if (put_dev)
nbd_put(nbd);
return ret;
}

6
include/uapi/linux/nbd.h
View File

@ -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 */