Btrfs: Fix a crash when mounting a subvolume
We should drop dentry before deactivating the superblock, otherwise
we can hit this bug:
BUG: Dentry f349a690{i=100,n=/} still in use (1) [unmount of btrfs loop1]
...
Steps to reproduce the bug:
# mount /dev/loop1 /mnt
# mkdir save
# btrfs subvolume snapshot /mnt save/snap1
# umount /mnt
# mount -o subvol=save/snap1 /dev/loop1 /mnt
(crash)
Reported-by: Michael Niederle <mniederle@gmx.at>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 47bf67c..61bd79a 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -685,9 +685,9 @@
mutex_unlock(&root->d_inode->i_mutex);
if (IS_ERR(new_root)) {
+ dput(root);
deactivate_locked_super(s);
error = PTR_ERR(new_root);
- dput(root);
goto error_free_subvol_name;
}
if (!new_root->d_inode) {