nbd: add device refcounting
In order to support deleting the device on disconnect we need to refcount the actual nbd_device struct. So add the refcounting framework and change how we free the normal devices at rmmod time so we can catch reference leaks. Signed-off-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Josef Bacik
Jens Axboe
Родитель
47d902b90a
Коммит
c6a4759ea0
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@ -99,10 +99,12 @@ struct nbd_device {
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int index;
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refcount_t config_refs;
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refcount_t refs;
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struct nbd_config *config;
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struct mutex config_lock;
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struct gendisk *disk;
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struct list_head list;
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struct task_struct *task_recv;
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struct task_struct *task_setup;
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};
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@ -165,6 +167,28 @@ static struct device_attribute pid_attr = {
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.show = pid_show,
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};
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static void nbd_dev_remove(struct nbd_device *nbd)
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{
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struct gendisk *disk = nbd->disk;
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if (disk) {
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del_gendisk(disk);
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blk_cleanup_queue(disk->queue);
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blk_mq_free_tag_set(&nbd->tag_set);
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put_disk(disk);
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}
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kfree(nbd);
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}
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static void nbd_put(struct nbd_device *nbd)
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{
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if (refcount_dec_and_mutex_lock(&nbd->refs,
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&nbd_index_mutex)) {
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idr_remove(&nbd_index_idr, nbd->index);
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mutex_unlock(&nbd_index_mutex);
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nbd_dev_remove(nbd);
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}
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}
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static int nbd_disconnected(struct nbd_config *config)
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{
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return test_bit(NBD_DISCONNECTED, &config->runtime_flags) ||
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@ -1005,6 +1029,7 @@ static void nbd_config_put(struct nbd_device *nbd)
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}
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nbd_reset(nbd);
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mutex_unlock(&nbd->config_lock);
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nbd_put(nbd);
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module_put(THIS_MODULE);
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}
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}
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@ -1199,6 +1224,10 @@ static int nbd_open(struct block_device *bdev, fmode_t mode)
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ret = -ENXIO;
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goto out;
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}
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if (!refcount_inc_not_zero(&nbd->refs)) {
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ret = -ENXIO;
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goto out;
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}
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if (!refcount_inc_not_zero(&nbd->config_refs)) {
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struct nbd_config *config;
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@ -1214,6 +1243,7 @@ static int nbd_open(struct block_device *bdev, fmode_t mode)
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goto out;
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}
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refcount_set(&nbd->config_refs, 1);
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refcount_inc(&nbd->refs);
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mutex_unlock(&nbd->config_lock);
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}
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out:
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@ -1225,6 +1255,7 @@ static void nbd_release(struct gendisk *disk, fmode_t mode)
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{
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struct nbd_device *nbd = disk->private_data;
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nbd_config_put(nbd);
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nbd_put(nbd);
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}
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static const struct block_device_operations nbd_fops =
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@ -1378,18 +1409,6 @@ static const struct blk_mq_ops nbd_mq_ops = {
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.timeout = nbd_xmit_timeout,
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};
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static void nbd_dev_remove(struct nbd_device *nbd)
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{
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struct gendisk *disk = nbd->disk;
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if (disk) {
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del_gendisk(disk);
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blk_cleanup_queue(disk->queue);
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blk_mq_free_tag_set(&nbd->tag_set);
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put_disk(disk);
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}
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kfree(nbd);
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}
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static int nbd_dev_add(int index)
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{
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struct nbd_device *nbd;
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@ -1452,6 +1471,8 @@ static int nbd_dev_add(int index)
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mutex_init(&nbd->config_lock);
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refcount_set(&nbd->config_refs, 0);
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refcount_set(&nbd->refs, 1);
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INIT_LIST_HEAD(&nbd->list);
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disk->major = NBD_MAJOR;
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disk->first_minor = index << part_shift;
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disk->fops = &nbd_fops;
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@ -1549,16 +1570,26 @@ again:
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} else {
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nbd = idr_find(&nbd_index_idr, index);
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}
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mutex_unlock(&nbd_index_mutex);
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if (!nbd) {
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printk(KERN_ERR "nbd: couldn't find device at index %d\n",
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index);
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mutex_unlock(&nbd_index_mutex);
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return -EINVAL;
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}
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if (!refcount_inc_not_zero(&nbd->refs)) {
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mutex_unlock(&nbd_index_mutex);
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if (index == -1)
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goto again;
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printk(KERN_ERR "nbd: device at index %d is going down\n",
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index);
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return -EINVAL;
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}
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mutex_unlock(&nbd_index_mutex);
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mutex_lock(&nbd->config_lock);
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if (refcount_read(&nbd->config_refs)) {
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mutex_unlock(&nbd->config_lock);
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nbd_put(nbd);
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if (index == -1)
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goto again;
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printk(KERN_ERR "nbd: nbd%d already in use\n", index);
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@ -1566,11 +1597,13 @@ again:
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}
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if (WARN_ON(nbd->config)) {
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mutex_unlock(&nbd->config_lock);
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nbd_put(nbd);
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return -EINVAL;
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}
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config = nbd->config = nbd_alloc_config();
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if (!nbd->config) {
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mutex_unlock(&nbd->config_lock);
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nbd_put(nbd);
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printk(KERN_ERR "nbd: couldn't allocate config\n");
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return -ENOMEM;
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}
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@ -1655,14 +1688,23 @@ static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
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index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
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mutex_lock(&nbd_index_mutex);
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nbd = idr_find(&nbd_index_idr, index);
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mutex_unlock(&nbd_index_mutex);
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if (!nbd) {
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mutex_unlock(&nbd_index_mutex);
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printk(KERN_ERR "nbd: couldn't find device at index %d\n",
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index);
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return -EINVAL;
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}
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if (!refcount_inc_not_zero(&nbd->config_refs))
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if (!refcount_inc_not_zero(&nbd->refs)) {
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mutex_unlock(&nbd_index_mutex);
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printk(KERN_ERR "nbd: device at index %d is going down\n",
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index);
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return -EINVAL;
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}
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mutex_unlock(&nbd_index_mutex);
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if (!refcount_inc_not_zero(&nbd->config_refs)) {
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nbd_put(nbd);
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return 0;
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}
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mutex_lock(&nbd->config_lock);
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nbd_disconnect(nbd);
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mutex_unlock(&nbd->config_lock);
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@ -1670,6 +1712,7 @@ static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
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&nbd->config->runtime_flags))
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nbd_config_put(nbd);
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nbd_config_put(nbd);
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nbd_put(nbd);
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return 0;
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}
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@ -1690,16 +1733,24 @@ static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
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index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
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mutex_lock(&nbd_index_mutex);
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nbd = idr_find(&nbd_index_idr, index);
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mutex_unlock(&nbd_index_mutex);
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if (!nbd) {
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mutex_unlock(&nbd_index_mutex);
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printk(KERN_ERR "nbd: couldn't find a device at index %d\n",
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index);
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return -EINVAL;
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}
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if (!refcount_inc_not_zero(&nbd->refs)) {
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mutex_unlock(&nbd_index_mutex);
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printk(KERN_ERR "nbd: device at index %d is going down\n",
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index);
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return -EINVAL;
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}
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mutex_unlock(&nbd_index_mutex);
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if (!refcount_inc_not_zero(&nbd->config_refs)) {
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dev_err(nbd_to_dev(nbd),
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"not configured, cannot reconfigure\n");
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nbd_put(nbd);
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return -EINVAL;
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}
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@ -1758,6 +1809,7 @@ static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
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out:
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mutex_unlock(&nbd->config_lock);
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nbd_config_put(nbd);
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nbd_put(nbd);
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return ret;
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}
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@ -2003,16 +2055,32 @@ static int __init nbd_init(void)
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static int nbd_exit_cb(int id, void *ptr, void *data)
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{
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struct list_head *list = (struct list_head *)data;
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struct nbd_device *nbd = ptr;
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nbd_dev_remove(nbd);
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refcount_inc(&nbd->refs);
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list_add_tail(&nbd->list, list);
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return 0;
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}
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static void __exit nbd_cleanup(void)
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{
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struct nbd_device *nbd;
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LIST_HEAD(del_list);
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nbd_dbg_close();
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idr_for_each(&nbd_index_idr, &nbd_exit_cb, NULL);
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mutex_lock(&nbd_index_mutex);
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idr_for_each(&nbd_index_idr, &nbd_exit_cb, &del_list);
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mutex_unlock(&nbd_index_mutex);
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list_for_each_entry(nbd, &del_list, list) {
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if (refcount_read(&nbd->refs) != 2)
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printk(KERN_ERR "nbd: possibly leaking a device\n");
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nbd_put(nbd);
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nbd_put(nbd);
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}
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idr_destroy(&nbd_index_idr);
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genl_unregister_family(&nbd_genl_family);
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destroy_workqueue(recv_workqueue);
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