btrfs: remove superfluous return value check at btrfs_dio_iomap_begin()

In the if statement that checks the return value from
btrfs_check_data_free_space(), there's no point to check if 'ret' is not
zero in the else branch, since the main if branch checked that it's zero,
so in the else branch it necessarily has a non-zero value.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: fdmanana

fs/btrfs/direct-io.c

@@ -439,8 +439,8 @@ static int btrfs_dio_iomap_begin(struct inode *inode, loff_t start,
 						  start, data_alloc_len, false);
 		if (!ret)
 			dio_data->data_space_reserved = true;
-		else if (ret && !(BTRFS_I(inode)->flags &
-				  (BTRFS_INODE_NODATACOW | BTRFS_INODE_PREALLOC)))
+		else if (!(BTRFS_I(inode)->flags &
+			   (BTRFS_INODE_NODATACOW | BTRFS_INODE_PREALLOC)))
 			goto err;
 	}