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nbd: Add the nbd NBD_DISCONNECT_ON_CLOSE config flag. 

If NBD_DISCONNECT_ON_CLOSE is set on a device, then the driver will
issue a disconnect from nbd_release if the device has no remaining
bdev->bd_openers.

Fix ret val so reconfigure with only setting the flag succeeds.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Doron Roberts-Kedes <doronrk@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Doron Roberts-Kedes 2018-06-15 14:05:32 -07:00 committed by Jens Axboe
parent ce042c183b
commit 08ba91ee6e
2 changed files with 37 additions and 8 deletions
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42
drivers/block/nbd.c
View File

@ -76,6 +76,7 @@ struct link_dead_args {
#define NBD_HAS_CONFIG_REF 4
#define NBD_BOUND 5
#define NBD_DESTROY_ON_DISCONNECT 6
#define NBD_DISCONNECT_ON_CLOSE 7
struct nbd_config {
u32 flags;
@ -138,6 +139,7 @@ static void nbd_config_put(struct nbd_device *nbd);
static void nbd_connect_reply(struct genl_info *info, int index);
static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info);
static void nbd_dead_link_work(struct work_struct *work);
static void nbd_disconnect_and_put(struct nbd_device *nbd);
static inline struct device *nbd_to_dev(struct nbd_device *nbd)
{
@ -1305,6 +1307,12 @@ static int nbd_open(struct block_device *bdev, fmode_t mode)
static void nbd_release(struct gendisk *disk, fmode_t mode)
{
struct nbd_device *nbd = disk->private_data;
struct block_device *bdev = bdget_disk(disk, 0);
if (test_bit(NBD_DISCONNECT_ON_CLOSE, &nbd->config->runtime_flags) &&
bdev->bd_openers == 0)
nbd_disconnect_and_put(nbd);
nbd_config_put(nbd);
nbd_put(nbd);
}
@ -1705,6 +1713,10 @@ static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)
&config->runtime_flags);
put_dev = true;
}
if (flags & NBD_CFLAG_DISCONNECT_ON_CLOSE) {
set_bit(NBD_DISCONNECT_ON_CLOSE,
&config->runtime_flags);
}
}
if (info->attrs[NBD_ATTR_SOCKETS]) {
@ -1749,6 +1761,17 @@ static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)
return ret;
}
static void nbd_disconnect_and_put(struct nbd_device *nbd)
{
mutex_lock(&nbd->config_lock);
nbd_disconnect(nbd);
nbd_clear_sock(nbd);
mutex_unlock(&nbd->config_lock);
if (test_and_clear_bit(NBD_HAS_CONFIG_REF,
&nbd->config->runtime_flags))
nbd_config_put(nbd);
}
static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
{
struct nbd_device *nbd;
@ -1781,13 +1804,7 @@ static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
nbd_put(nbd);
return 0;
}
mutex_lock(&nbd->config_lock);
nbd_disconnect(nbd);
nbd_clear_sock(nbd);
mutex_unlock(&nbd->config_lock);
if (test_and_clear_bit(NBD_HAS_CONFIG_REF,
&nbd->config->runtime_flags))
nbd_config_put(nbd);
nbd_disconnect_and_put(nbd);
nbd_config_put(nbd);
nbd_put(nbd);
return 0;
@ -1798,7 +1815,7 @@ static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
struct nbd_device *nbd = NULL;
struct nbd_config *config;
int index;
int ret = -EINVAL;
int ret = 0;
bool put_dev = false;
if (!netlink_capable(skb, CAP_SYS_ADMIN))
@ -1838,6 +1855,7 @@ static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
!nbd->task_recv) {
dev_err(nbd_to_dev(nbd),
"not configured, cannot reconfigure\n");
ret = -EINVAL;
goto out;
}
@ -1862,6 +1880,14 @@ static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
&config->runtime_flags))
refcount_inc(&nbd->refs);
}
if (flags & NBD_CFLAG_DISCONNECT_ON_CLOSE) {
set_bit(NBD_DISCONNECT_ON_CLOSE,
&config->runtime_flags);
} else {
clear_bit(NBD_DISCONNECT_ON_CLOSE,
&config->runtime_flags);
}
}
if (info->attrs[NBD_ATTR_SOCKETS]) {

3
include/uapi/linux/nbd.h
View File

@ -53,6 +53,9 @@ enum {
/* These are client behavior specific flags. */
#define NBD_CFLAG_DESTROY_ON_DISCONNECT (1 << 0) /* delete the nbd device on
disconnect. */
#define NBD_CFLAG_DISCONNECT_ON_CLOSE (1 << 1) /* disconnect the nbd device on
* close by last opener.
*/
/* userspace doesn't need the nbd_device structure */