diff --git a/fs/nilfs2/cpfile.c b/fs/nilfs2/cpfile.c
index 1c6cfb59128d..3f5d5d06f53c 100644
--- a/fs/nilfs2/cpfile.c
+++ b/fs/nilfs2/cpfile.c
@@ -871,7 +871,6 @@ int nilfs_cpfile_change_cpmode(struct inode *cpfile, __u64 cno, int mode)
 		 * exclusive with a new mount job.  Though it doesn't cover
 		 * umount, it's enough for the purpose.
 		 */
-		mutex_lock(&nilfs->ns_mount_mutex);
 		if (nilfs_checkpoint_is_mounted(nilfs, cno, 1)) {
 			/* Current implementation does not have to protect
 			   plain read-only mounts since they are exclusive
@@ -880,7 +879,6 @@ int nilfs_cpfile_change_cpmode(struct inode *cpfile, __u64 cno, int mode)
 			ret = -EBUSY;
 		} else
 			ret = nilfs_cpfile_clear_snapshot(cpfile, cno);
-		mutex_unlock(&nilfs->ns_mount_mutex);
 		return ret;
 	case NILFS_SNAPSHOT:
 		return nilfs_cpfile_set_snapshot(cpfile, cno);
diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c
index 5040220c3732..2a0a5a3ac134 100644
--- a/fs/nilfs2/inode.c
+++ b/fs/nilfs2/inode.c
@@ -664,7 +664,6 @@ int nilfs_load_inode_block(struct nilfs_sb_info *sbi, struct inode *inode,
 	int err;
 
 	spin_lock(&sbi->s_inode_lock);
-	/* Caller of this function MUST lock s_inode_lock */
 	if (ii->i_bh == NULL) {
 		spin_unlock(&sbi->s_inode_lock);
 		err = nilfs_ifile_get_inode_block(sbi->s_ifile, inode->i_ino,
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;
 }
 
diff --git a/include/linux/nilfs2_fs.h b/include/linux/nilfs2_fs.h
index 79fec6af3f9f..ce520402e840 100644
--- a/include/linux/nilfs2_fs.h
+++ b/include/linux/nilfs2_fs.h
@@ -424,15 +424,6 @@ struct nilfs_dat_entry {
 	__le64 de_rsv;
 };
 
-/**
- * struct nilfs_dat_group_desc - block group descriptor
- * @dg_nfrees: number of free virtual block numbers in block group
- */
-struct nilfs_dat_group_desc {
-	__le32 dg_nfrees;
-};
-
-
 /**
  * struct nilfs_snapshot_list - snapshot list
  * @ssl_next: next checkpoint number on snapshot list