korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-11-11 04:18:39 +08:00
Code Issues Packages Projects Releases Wiki Activity

nbd: remove nbd->destroy_complete

Browse Source 
The nbd->destroy_complete pointer is not really needed.  For creating
a device without a specific index we now simplify skip devices marked
NBD_DESTROY_ON_DISCONNECT as there is not much point to reuse them.
For device creation with a specific index there is no real need to
treat the case of a requested but not finished disconnect different
than any other device that is being shutdown, i.e. we can just return
an error, as a slightly different race window would anyway.

Fixes: 6e4df4c648 ("nbd: reduce the nbd_index_mutex scope")
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: syzbot+2c98885bcd769f56b6d6@syzkaller.appspotmail.com
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20210825163108.50713-7-hch@lst.de
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2021-08-25 18:31:08 +02:00 committed by Jens Axboe
parent 438cd318c8
commit 7ee656c3ac
1 changed files with 15 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

54
drivers/block/nbd.c
View File

@ -120,7 +120,6 @@ struct nbd_device {
struct task_struct *task_recv;
struct task_struct *task_setup;
struct completion *destroy_complete;
unsigned long flags;
char *backend;
@ -235,19 +234,6 @@ static const struct device_attribute backend_attr = {
.show = backend_show,
};
/*
* 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.
*/
static void nbd_notify_destroy_completion(struct nbd_device *nbd)
{
if (test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags) &&
nbd->destroy_complete)
complete(nbd->destroy_complete);
}
static void nbd_dev_remove(struct nbd_device *nbd)
{
struct gendisk *disk = nbd->disk;
@ -262,7 +248,6 @@ static void nbd_dev_remove(struct nbd_device *nbd)
*/
mutex_lock(&nbd_index_mutex);
idr_remove(&nbd_index_idr, nbd->index);
nbd_notify_destroy_completion(nbd);
mutex_unlock(&nbd_index_mutex);
kfree(nbd);
@ -1702,7 +1687,6 @@ static struct nbd_device *nbd_dev_add(int index, unsigned int refs)
BLK_MQ_F_BLOCKING;
nbd->tag_set.driver_data = nbd;
INIT_WORK(&nbd->remove_work, nbd_dev_remove_work);
nbd->destroy_complete = NULL;
nbd->backend = NULL;
err = blk_mq_alloc_tag_set(&nbd->tag_set);
@ -1854,7 +1838,6 @@ static int nbd_genl_size_set(struct genl_info *info, struct nbd_device *nbd)
static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)
{
DECLARE_COMPLETION_ONSTACK(destroy_complete);
struct nbd_device *nbd;
struct nbd_config *config;
int index = -1;
@ -1876,31 +1859,24 @@ static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)
}
again:
mutex_lock(&nbd_index_mutex);
if (index == -1)
if (index == -1) {
nbd = nbd_find_get_unused();
else
nbd = idr_find(&nbd_index_idr, index);
if (nbd && index != -1) {
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 until the nbd device is completely destroyed */
wait_for_completion(&destroy_complete);
goto again;
}
if (!refcount_inc_not_zero(&nbd->refs)) {
mutex_unlock(&nbd_index_mutex);
pr_err("nbd: device at index %d is going down\n",
index);
return -EINVAL;
}
mutex_unlock(&nbd_index_mutex);
} else {
mutex_unlock(&nbd_index_mutex);
nbd = idr_find(&nbd_index_idr, index);
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);
pr_err("nbd: device at index %d is going down\n",
index);
return -EINVAL;
}
}
}
mutex_unlock(&nbd_index_mutex);
if (!nbd) {
nbd = nbd_dev_add(index, 2);
if (IS_ERR(nbd)) {
pr_err("nbd: failed to add new device\n");