static DEFINE_IDR(nbd_index_idr);
static DEFINE_MUTEX(nbd_index_mutex);
+static struct workqueue_struct *nbd_del_wq;
static int nbd_total_devices = 0;
struct nbd_sock {
struct mutex config_lock;
struct gendisk *disk;
struct workqueue_struct *recv_workq;
+ struct work_struct remove_work;
struct list_head list;
struct task_struct *task_recv;
struct task_struct *task_setup;
- struct completion *destroy_complete;
unsigned long flags;
char *backend;
{
struct gendisk *disk = nbd->disk;
- if (disk) {
- del_gendisk(disk);
- blk_cleanup_disk(disk);
- blk_mq_free_tag_set(&nbd->tag_set);
- }
+ del_gendisk(disk);
+ blk_cleanup_disk(disk);
+ blk_mq_free_tag_set(&nbd->tag_set);
/*
- * Place this in the last just before the nbd is freed to
- * make sure that the disk and the related kobject are also
- * totally removed to avoid duplicate creation of the same
- * one.
+ * Remove from idr after del_gendisk() completes, so if the same ID is
+ * reused, the following add_disk() will succeed.
*/
- if (test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags) && nbd->destroy_complete)
- complete(nbd->destroy_complete);
+ mutex_lock(&nbd_index_mutex);
+ idr_remove(&nbd_index_idr, nbd->index);
+ mutex_unlock(&nbd_index_mutex);
kfree(nbd);
}
+static void nbd_dev_remove_work(struct work_struct *work)
+{
+ nbd_dev_remove(container_of(work, struct nbd_device, remove_work));
+}
+
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);
+ if (!refcount_dec_and_test(&nbd->refs))
+ return;
+
+ /* Call del_gendisk() asynchrounously to prevent deadlock */
+ if (test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags))
+ queue_work(nbd_del_wq, &nbd->remove_work);
+ else
nbd_dev_remove(nbd);
- mutex_unlock(&nbd_index_mutex);
- }
}
static int nbd_disconnected(struct nbd_config *config)
unsigned int cmd, unsigned long arg)
{
struct nbd_config *config = nbd->config;
+ loff_t bytesize;
switch (cmd) {
case NBD_DISCONNECT:
case NBD_SET_SIZE:
return nbd_set_size(nbd, arg, config->blksize);
case NBD_SET_SIZE_BLOCKS:
- return nbd_set_size(nbd, arg * config->blksize,
- config->blksize);
+ if (check_mul_overflow((loff_t)arg, config->blksize, &bytesize))
+ return -EINVAL;
+ return nbd_set_size(nbd, bytesize, config->blksize);
case NBD_SET_TIMEOUT:
nbd_set_cmd_timeout(nbd, arg);
return 0;
.timeout = nbd_xmit_timeout,
};
-static int nbd_dev_add(int index)
+static struct nbd_device *nbd_dev_add(int index, unsigned int refs)
{
struct nbd_device *nbd;
struct gendisk *disk;
nbd->tag_set.flags = BLK_MQ_F_SHOULD_MERGE |
BLK_MQ_F_BLOCKING;
nbd->tag_set.driver_data = nbd;
- nbd->destroy_complete = NULL;
+ INIT_WORK(&nbd->remove_work, nbd_dev_remove_work);
nbd->backend = NULL;
err = blk_mq_alloc_tag_set(&nbd->tag_set);
if (err)
goto out_free_nbd;
+ mutex_lock(&nbd_index_mutex);
if (index >= 0) {
err = idr_alloc(&nbd_index_idr, nbd, index, index + 1,
GFP_KERNEL);
if (err >= 0)
index = err;
}
+ nbd->index = index;
+ mutex_unlock(&nbd_index_mutex);
if (err < 0)
goto out_free_tags;
- nbd->index = index;
disk = blk_mq_alloc_disk(&nbd->tag_set, NULL);
if (IS_ERR(disk)) {
mutex_init(&nbd->config_lock);
refcount_set(&nbd->config_refs, 0);
- refcount_set(&nbd->refs, 1);
+ /*
+ * Start out with a zero references to keep other threads from using
+ * this device until it is fully initialized.
+ */
+ refcount_set(&nbd->refs, 0);
INIT_LIST_HEAD(&nbd->list);
disk->major = NBD_MAJOR;
+
+ /* Too big first_minor can cause duplicate creation of
+ * sysfs files/links, since first_minor will be truncated to
+ * byte in __device_add_disk().
+ */
disk->first_minor = index << part_shift;
+ if (disk->first_minor > 0xff) {
+ err = -EINVAL;
+ goto out_free_idr;
+ }
+
disk->minors = 1 << part_shift;
disk->fops = &nbd_fops;
disk->private_data = nbd;
sprintf(disk->disk_name, "nbd%d", index);
add_disk(disk);
+
+ /*
+ * Now publish the device.
+ */
+ refcount_set(&nbd->refs, refs);
nbd_total_devices++;
- return index;
+ return nbd;
out_free_idr:
+ mutex_lock(&nbd_index_mutex);
idr_remove(&nbd_index_idr, index);
+ mutex_unlock(&nbd_index_mutex);
out_free_tags:
blk_mq_free_tag_set(&nbd->tag_set);
out_free_nbd:
kfree(nbd);
out:
- return err;
+ return ERR_PTR(err);
}
-static int find_free_cb(int id, void *ptr, void *data)
+static struct nbd_device *nbd_find_get_unused(void)
{
- struct nbd_device *nbd = ptr;
- struct nbd_device **found = data;
+ struct nbd_device *nbd;
+ int id;
- if (!refcount_read(&nbd->config_refs)) {
- *found = nbd;
- return 1;
+ lockdep_assert_held(&nbd_index_mutex);
+
+ idr_for_each_entry(&nbd_index_idr, nbd, id) {
+ if (refcount_read(&nbd->config_refs) ||
+ test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags))
+ continue;
+ if (refcount_inc_not_zero(&nbd->refs))
+ return nbd;
}
- return 0;
+
+ return NULL;
}
/* Netlink interface. */
static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)
{
- DECLARE_COMPLETION_ONSTACK(destroy_complete);
- struct nbd_device *nbd = NULL;
+ struct nbd_device *nbd;
struct nbd_config *config;
int index = -1;
int ret;
again:
mutex_lock(&nbd_index_mutex);
if (index == -1) {
- ret = idr_for_each(&nbd_index_idr, &find_free_cb, &nbd);
- if (ret == 0) {
- int new_index;
- new_index = nbd_dev_add(-1);
- if (new_index < 0) {
- mutex_unlock(&nbd_index_mutex);
- printk(KERN_ERR "nbd: failed to add new device\n");
- return new_index;
- }
- nbd = idr_find(&nbd_index_idr, new_index);
- }
+ nbd = nbd_find_get_unused();
} else {
nbd = idr_find(&nbd_index_idr, index);
- if (!nbd) {
- ret = nbd_dev_add(index);
- if (ret < 0) {
+ if (nbd) {
+ if ((test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags) &&
+ test_bit(NBD_DISCONNECT_REQUESTED, &nbd->flags)) ||
+ !refcount_inc_not_zero(&nbd->refs)) {
mutex_unlock(&nbd_index_mutex);
- printk(KERN_ERR "nbd: failed to add new device\n");
- return ret;
+ pr_err("nbd: device at index %d is going down\n",
+ index);
+ return -EINVAL;
}
- nbd = idr_find(&nbd_index_idr, index);
}
}
- if (!nbd) {
- printk(KERN_ERR "nbd: couldn't find device at index %d\n",
- index);
- mutex_unlock(&nbd_index_mutex);
- return -EINVAL;
- }
-
- if (test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags) &&
- test_bit(NBD_DISCONNECT_REQUESTED, &nbd->flags)) {
- nbd->destroy_complete = &destroy_complete;
- mutex_unlock(&nbd_index_mutex);
-
- /* Wait untill the the nbd stuff is totally destroyed */
- wait_for_completion(&destroy_complete);
- goto again;
- }
+ mutex_unlock(&nbd_index_mutex);
- 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;
+ if (!nbd) {
+ nbd = nbd_dev_add(index, 2);
+ if (IS_ERR(nbd)) {
+ pr_err("nbd: failed to add new device\n");
+ return PTR_ERR(nbd);
+ }
}
- mutex_unlock(&nbd_index_mutex);
mutex_lock(&nbd->config_lock);
if (refcount_read(&nbd->config_refs)) {
if (register_blkdev(NBD_MAJOR, "nbd"))
return -EIO;
+ nbd_del_wq = alloc_workqueue("nbd-del", WQ_UNBOUND, 0);
+ if (!nbd_del_wq) {
+ unregister_blkdev(NBD_MAJOR, "nbd");
+ return -ENOMEM;
+ }
+
if (genl_register_family(&nbd_genl_family)) {
+ destroy_workqueue(nbd_del_wq);
unregister_blkdev(NBD_MAJOR, "nbd");
return -EINVAL;
}
nbd_dbg_init();
- mutex_lock(&nbd_index_mutex);
for (i = 0; i < nbds_max; i++)
- nbd_dev_add(i);
- mutex_unlock(&nbd_index_mutex);
+ nbd_dev_add(i, 1);
return 0;
}
struct list_head *list = (struct list_head *)data;
struct nbd_device *nbd = ptr;
- list_add_tail(&nbd->list, list);
+ /* Skip nbd that is being removed asynchronously */
+ if (refcount_read(&nbd->refs))
+ list_add_tail(&nbd->list, list);
+
return 0;
}
nbd_put(nbd);
}
+ /* Also wait for nbd_dev_remove_work() completes */
+ destroy_workqueue(nbd_del_wq);
+
idr_destroy(&nbd_index_idr);
genl_unregister_family(&nbd_genl_family);
unregister_blkdev(NBD_MAJOR, "nbd");
projects / linux-2.6-microblaze.git / blobdiff