1 files changed, 5 insertions, 1 deletions

diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index d24057d58f17..f6af76042d80 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -99,7 +99,8 @@ static int nilfs_ioctl_wrap_copy(struct the_nilfs *nilfs,
 static int nilfs_ioctl_change_cpmode(struct inode *inode, struct file *filp,
                                      unsigned int cmd, void __user *argp)
 {
-        struct inode *cpfile = NILFS_SB(inode->i_sb)->s_nilfs->ns_cpfile;
+        struct the_nilfs *nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
+        struct inode *cpfile = nilfs->ns_cpfile;
         struct nilfs_transaction_info ti;
         struct nilfs_cpmode cpmode;
         int ret;
@@ -109,14 +110,17 @@ static int nilfs_ioctl_change_cpmode(struct inode *inode, struct file *filp,
         if (copy_from_user(&cpmode, argp, sizeof(cpmode)))
                 return -EFAULT;
 
+        mutex_lock(&nilfs->ns_mount_mutex);
         nilfs_transaction_begin(inode->i_sb, &ti, 0);
         ret = nilfs_cpfile_change_cpmode(
                 cpfile, cpmode.cm_cno, cpmode.cm_mode);
         if (unlikely(ret < 0)) {
                 nilfs_transaction_abort(inode->i_sb);
+                mutex_unlock(&nilfs->ns_mount_mutex);
                 return ret;
         }
         nilfs_transaction_commit(inode->i_sb); /* never fails */
+        mutex_unlock(&nilfs->ns_mount_mutex);
         return ret;
 }