From 862488105b84ca744b3d8ff131e0fcfe10644be1 Mon Sep 17 00:00:00 2001
From: Xiubo Li <xiubli@redhat.com>
Date: Thu, 19 Sep 2019 11:44:27 +0530
Subject: [PATCH] nbd: fix possible sysfs duplicate warning
Git-commit: 862488105b84ca744b3d8ff131e0fcfe10644be1
Patch-mainline: v5.4-rc3
References: git-fixes
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 <mchristi@redhat.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Coly Li <colyli@suse.de>
---
drivers/block/nbd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
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);
nbd_dev_remove(nbd);
+ mutex_unlock(&nbd_index_mutex);
}
}
--
2.35.3