Re: [PATCH] xfs: shutdown on failure to add page to log bio

[Christoph Hellwig <hch@infradead.org>]

On Wed, Mar 25, 2020 at 07:25:02AM -0400, Brian Foster wrote:
> diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
> index 2a90a483c2d6..92a58a6bc32b 100644
> --- a/fs/xfs/xfs_log.c
> +++ b/fs/xfs/xfs_log.c
> @@ -1703,7 +1703,7 @@ xlog_bio_end_io(
>  		   &iclog->ic_end_io_work);
>  }
>  
> -static void
> +static int
>  xlog_map_iclog_data(
>  	struct bio		*bio,
>  	void			*data,
> @@ -1714,11 +1714,14 @@ xlog_map_iclog_data(
>  		unsigned int	off = offset_in_page(data);
>  		size_t		len = min_t(size_t, count, PAGE_SIZE - off);
>  
> -		WARN_ON_ONCE(bio_add_page(bio, page, len, off) != len);
> +		if (bio_add_page(bio, page, len, off) != len)
> +			break;

I'd just return -EIO here.

>  
>  		data += len;
>  		count -= len;
>  	} while (count);
> +
> +	return count;

And 0 here.  Returning the remaining count obviously works as well,
but it feels a little unintuitive to me and would warrant a comment.