convert cifs_ioctl_copychunk()

fdput() moved past mnt_drop_file_write(); harmless, if somewhat cringeworthy.
Reordering could be avoided either by adding an explicit scope or by making
mnt_drop_file_write() called via __cleanup.

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Author: Al Viro

fs/smb/client/ioctl.c

@@ -72,7 +72,6 @@ static long cifs_ioctl_copychunk(unsigned int xid, struct file *dst_file,
 			unsigned long srcfd)
 {
 	int rc;
-	struct fd src_file;
 	struct inode *src_inode;
 
 	cifs_dbg(FYI, "ioctl copychunk range\n");
@@ -89,29 +88,27 @@ static long cifs_ioctl_copychunk(unsigned int xid, struct file *dst_file,
 		return rc;
 	}
 
-	src_file = fdget(srcfd);
-	if (!fd_file(src_file)) {
+	CLASS(fd, src_file)(srcfd);
+	if (fd_empty(src_file)) {
 		rc = -EBADF;
 		goto out_drop_write;
 	}
 
 	if (fd_file(src_file)->f_op->unlocked_ioctl != cifs_ioctl) {
 		rc = -EBADF;
 		cifs_dbg(VFS, "src file seems to be from a different filesystem type\n");
-		goto out_fput;
+		goto out_drop_write;
 	}
 
 	src_inode = file_inode(fd_file(src_file));
 	rc = -EINVAL;
 	if (S_ISDIR(src_inode->i_mode))
-		goto out_fput;
+		goto out_drop_write;
 
 	rc = cifs_file_copychunk_range(xid, fd_file(src_file), 0, dst_file, 0,
 					src_inode->i_size, 0);
 	if (rc > 0)
 		rc = 0;
-out_fput:
-	fdput(src_file);
 out_drop_write:
 	mnt_drop_write_file(dst_file);
 	return rc;