Btrfs: Various small fixes.

This trivial patch contains two locking fixes and a off by one fix.

---

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index a6a418b6894b..eb4b357d05e1 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -449,7 +449,9 @@ static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
                 s->s_flags |= MS_ACTIVE;
         }
 
+        mutex_lock(&s->s_root->d_inode->i_mutex);
         root = lookup_one_len(subvol_name, s->s_root, strlen(subvol_name));
+        mutex_unlock(&s->s_root->d_inode->i_mutex);
         if (IS_ERR(root)) {
                 up_write(&s->s_umount);
                 deactivate_super(s);