diff options
authorXiubo Li <>2019-09-19 11:44:27 +0530
committerJens Axboe <>2019-10-10 09:44:56 -0600
commit862488105b84ca744b3d8ff131e0fcfe10644be1 (patch)
parent79a85e214d62da9a750cc63ef49483e62abbda81 (diff)
nbd: fix possible sysfs duplicate warningfor-linus-20191010
1. nbd_put takes the mutex and drops nbd->ref to 0. It then does idr_remove and drops the mutex. 2. nbd_genl_connect takes the mutex. idr_find/idr_for_each fails to find an existing device, so it does nbd_dev_add. 3. just before the nbd_put could call nbd_dev_remove or not finished totally, but if nbd_dev_add try to add_disk, we can hit: debugfs: Directory 'nbd1' with parent 'block' already present! This patch will make sure all the disk add/remove stuff are done by holding the nbd_index_mutex lock. Reported-by: Mike Christie <> Reviewed-by: Josef Bacik <> Signed-off-by: Xiubo Li <> Signed-off-by: Jens Axboe <>
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index ac07e8c94c79..478aa86fc1f2 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -248,8 +248,8 @@ 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);
+ mutex_unlock(&nbd_index_mutex);