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>
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index cb45d79..4237e72 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -99,10 +99,12 @@
int index;
refcount_t config_refs;
+ refcount_t refs;
struct nbd_config *config;
struct mutex config_lock;
struct gendisk *disk;
+ struct list_head list;
struct task_struct *task_recv;
struct task_struct *task_setup;
};
@@ -165,6 +167,28 @@
.show = pid_show,
};
+static void nbd_dev_remove(struct nbd_device *nbd)
+{
+ struct gendisk *disk = nbd->disk;
+ if (disk) {
+ del_gendisk(disk);
+ blk_cleanup_queue(disk->queue);
+ blk_mq_free_tag_set(&nbd->tag_set);
+ put_disk(disk);
+ }
+ kfree(nbd);
+}
+
+static void nbd_put(struct nbd_device *nbd)
+{
+ if (refcount_dec_and_mutex_lock(&nbd->refs,
+ &nbd_index_mutex)) {
+ idr_remove(&nbd_index_idr, nbd->index);
+ mutex_unlock(&nbd_index_mutex);
+ nbd_dev_remove(nbd);
+ }
+}
+
static int nbd_disconnected(struct nbd_config *config)
{
return test_bit(NBD_DISCONNECTED, &config->runtime_flags) ||
@@ -1005,6 +1029,7 @@
}
nbd_reset(nbd);
mutex_unlock(&nbd->config_lock);
+ nbd_put(nbd);
module_put(THIS_MODULE);
}
}
@@ -1199,6 +1224,10 @@
ret = -ENXIO;
goto out;
}
+ if (!refcount_inc_not_zero(&nbd->refs)) {
+ ret = -ENXIO;
+ goto out;
+ }
if (!refcount_inc_not_zero(&nbd->config_refs)) {
struct nbd_config *config;
@@ -1214,6 +1243,7 @@
goto out;
}
refcount_set(&nbd->config_refs, 1);
+ refcount_inc(&nbd->refs);
mutex_unlock(&nbd->config_lock);
}
out:
@@ -1225,6 +1255,7 @@
{
struct nbd_device *nbd = disk->private_data;
nbd_config_put(nbd);
+ nbd_put(nbd);
}
static const struct block_device_operations nbd_fops =
@@ -1378,18 +1409,6 @@
.timeout = nbd_xmit_timeout,
};
-static void nbd_dev_remove(struct nbd_device *nbd)
-{
- struct gendisk *disk = nbd->disk;
- if (disk) {
- del_gendisk(disk);
- blk_cleanup_queue(disk->queue);
- blk_mq_free_tag_set(&nbd->tag_set);
- put_disk(disk);
- }
- kfree(nbd);
-}
-
static int nbd_dev_add(int index)
{
struct nbd_device *nbd;
@@ -1452,6 +1471,8 @@
mutex_init(&nbd->config_lock);
refcount_set(&nbd->config_refs, 0);
+ refcount_set(&nbd->refs, 1);
+ INIT_LIST_HEAD(&nbd->list);
disk->major = NBD_MAJOR;
disk->first_minor = index << part_shift;
disk->fops = &nbd_fops;
@@ -1549,16 +1570,26 @@
} else {
nbd = idr_find(&nbd_index_idr, index);
}
- mutex_unlock(&nbd_index_mutex);
if (!nbd) {
printk(KERN_ERR "nbd: couldn't find device at index %d\n",
index);
+ mutex_unlock(&nbd_index_mutex);
return -EINVAL;
}
+ if (!refcount_inc_not_zero(&nbd->refs)) {
+ mutex_unlock(&nbd_index_mutex);
+ if (index == -1)
+ goto again;
+ printk(KERN_ERR "nbd: device at index %d is going down\n",
+ index);
+ return -EINVAL;
+ }
+ mutex_unlock(&nbd_index_mutex);
mutex_lock(&nbd->config_lock);
if (refcount_read(&nbd->config_refs)) {
mutex_unlock(&nbd->config_lock);
+ nbd_put(nbd);
if (index == -1)
goto again;
printk(KERN_ERR "nbd: nbd%d already in use\n", index);
@@ -1566,11 +1597,13 @@
}
if (WARN_ON(nbd->config)) {
mutex_unlock(&nbd->config_lock);
+ nbd_put(nbd);
return -EINVAL;
}
config = nbd->config = nbd_alloc_config();
if (!nbd->config) {
mutex_unlock(&nbd->config_lock);
+ nbd_put(nbd);
printk(KERN_ERR "nbd: couldn't allocate config\n");
return -ENOMEM;
}
@@ -1655,14 +1688,23 @@
index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
mutex_lock(&nbd_index_mutex);
nbd = idr_find(&nbd_index_idr, index);
- mutex_unlock(&nbd_index_mutex);
if (!nbd) {
+ mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: couldn't find device at index %d\n",
index);
return -EINVAL;
}
- if (!refcount_inc_not_zero(&nbd->config_refs))
+ if (!refcount_inc_not_zero(&nbd->refs)) {
+ mutex_unlock(&nbd_index_mutex);
+ printk(KERN_ERR "nbd: device at index %d is going down\n",
+ index);
+ return -EINVAL;
+ }
+ mutex_unlock(&nbd_index_mutex);
+ if (!refcount_inc_not_zero(&nbd->config_refs)) {
+ nbd_put(nbd);
return 0;
+ }
mutex_lock(&nbd->config_lock);
nbd_disconnect(nbd);
mutex_unlock(&nbd->config_lock);
@@ -1670,6 +1712,7 @@
&nbd->config->runtime_flags))
nbd_config_put(nbd);
nbd_config_put(nbd);
+ nbd_put(nbd);
return 0;
}
@@ -1690,16 +1733,24 @@
index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
mutex_lock(&nbd_index_mutex);
nbd = idr_find(&nbd_index_idr, index);
- mutex_unlock(&nbd_index_mutex);
if (!nbd) {
+ mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: couldn't find a device at index %d\n",
index);
return -EINVAL;
}
+ if (!refcount_inc_not_zero(&nbd->refs)) {
+ mutex_unlock(&nbd_index_mutex);
+ printk(KERN_ERR "nbd: device at index %d is going down\n",
+ index);
+ return -EINVAL;
+ }
+ mutex_unlock(&nbd_index_mutex);
if (!refcount_inc_not_zero(&nbd->config_refs)) {
dev_err(nbd_to_dev(nbd),
"not configured, cannot reconfigure\n");
+ nbd_put(nbd);
return -EINVAL;
}
@@ -1758,6 +1809,7 @@
out:
mutex_unlock(&nbd->config_lock);
nbd_config_put(nbd);
+ nbd_put(nbd);
return ret;
}
@@ -2003,16 +2055,32 @@
static int nbd_exit_cb(int id, void *ptr, void *data)
{
+ struct list_head *list = (struct list_head *)data;
struct nbd_device *nbd = ptr;
- nbd_dev_remove(nbd);
+
+ refcount_inc(&nbd->refs);
+ list_add_tail(&nbd->list, list);
return 0;
}
static void __exit nbd_cleanup(void)
{
+ struct nbd_device *nbd;
+ LIST_HEAD(del_list);
+
nbd_dbg_close();
- idr_for_each(&nbd_index_idr, &nbd_exit_cb, NULL);
+ mutex_lock(&nbd_index_mutex);
+ idr_for_each(&nbd_index_idr, &nbd_exit_cb, &del_list);
+ mutex_unlock(&nbd_index_mutex);
+
+ list_for_each_entry(nbd, &del_list, list) {
+ if (refcount_read(&nbd->refs) != 2)
+ printk(KERN_ERR "nbd: possibly leaking a device\n");
+ nbd_put(nbd);
+ nbd_put(nbd);
+ }
+
idr_destroy(&nbd_index_idr);
genl_unregister_family(&nbd_genl_family);
destroy_workqueue(recv_workqueue);