ksmbd: fix open failure from block and char device file

char/block device file can't be opened with dentry_open() if device driver
is not loaded. Use O_PATH flags for fake opening file to handle it if file
is a block or char file.
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/server/smb2pdu.c

@@ -2052,18 +2052,20 @@ int smb2_tree_connect(struct ksmbd_work *work)
  * @access:		file access flags
  * @disposition:	file disposition flags
  * @may_flags:		set with MAY_ flags
- * @is_dir:		is creating open flags for directory
+ * @coptions:		file creation options
+ * @mode:		file mode
  *
  * Return:      file open flags
  */
 static int smb2_create_open_flags(bool file_present, __le32 access,
 				  __le32 disposition,
 				  int *may_flags,
-				  bool is_dir)
+				  __le32 coptions,
+				  umode_t mode)
 {
 	int oflags = O_NONBLOCK | O_LARGEFILE;
 
-	if (is_dir) {
+	if (coptions & FILE_DIRECTORY_FILE_LE || S_ISDIR(mode)) {
 		access &= ~FILE_WRITE_DESIRE_ACCESS_LE;
 		ksmbd_debug(SMB, "Discard write access to a directory\n");
 	}
@@ -2080,7 +2082,7 @@ static int smb2_create_open_flags(bool file_present, __le32 access,
 		*may_flags = MAY_OPEN | MAY_READ;
 	}
 
-	if (access == FILE_READ_ATTRIBUTES_LE)
+	if (access == FILE_READ_ATTRIBUTES_LE || S_ISBLK(mode) || S_ISCHR(mode))
 		oflags |= O_PATH;
 
 	if (file_present) {
@@ -3175,8 +3177,8 @@ int smb2_open(struct ksmbd_work *work)
 	open_flags = smb2_create_open_flags(file_present, daccess,
 					    req->CreateDisposition,
 					    &may_flags,
-		req->CreateOptions & FILE_DIRECTORY_FILE_LE ||
-		(file_present && S_ISDIR(d_inode(path.dentry)->i_mode)));
+					    req->CreateOptions,
+					    file_present ? d_inode(path.dentry)->i_mode : 0);
 
 	if (!test_tree_conn_flag(tcon, KSMBD_TREE_CONN_FLAG_WRITABLE)) {
 		if (open_flags & (O_CREAT | O_TRUNC)) {