[PATCH RFC v2 for-6.8/block 15/18] buffer: add a new helper to read sb block

[Christoph Hellwig]

On Mon, Dec 11, 2023 at 10:07:53PM +0800, Yu Kuai wrote:
> +static __always_inline int buffer_uptodate_or_error(struct buffer_head *bh)
> +{
> +	/*
> +	 * If the buffer has the write error flag, data was failed to write
> +	 * out in the block. In this case, set buffer uptodate to prevent
> +	 * reading old data.
> +	 */
> +	if (buffer_write_io_error(bh))
> +		set_buffer_uptodate(bh);
> +	return buffer_uptodate(bh);
> +}

So - risking this blows up into a lot of nasty work: Why do we even
clear the uptodate flag on write errors?  Doing so makes not sense to
me as the data isn't any less uptodate just because we failed to write
it..