fs/ntfs3: Fix missing i_op in ntfs_read_mft

There is null pointer dereference because i_op == NULL.
The bug happens because we don't initialize i_op for records in $Extend.
Fixes: 82cae269 ("fs/ntfs3: Add initialization of super block")
Reported-by: Liangbin Lian <jjm2473@gmail.com>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

fs/ntfs3/inode.c

@@ -430,6 +430,7 @@ static struct inode *ntfs_read_mft(struct inode *inode,
 	} else if (fname && fname->home.low == cpu_to_le32(MFT_REC_EXTEND) &&
 		   fname->home.seq == cpu_to_le16(MFT_REC_EXTEND)) {
 		/* Records in $Extend are not a files or general directories. */
+		inode->i_op = &ntfs_file_inode_operations;
 	} else {
 		err = -EINVAL;
 		goto out;