[PATCHv9 4/7] block, fs: add write hint to kiocb

[Christoph Hellwig]

On Fri, Oct 25, 2024 at 02:36:42PM -0700, Keith Busch wrote:
> +static u16 blkdev_write_hint(struct kiocb *iocb, struct block_device *bdev)
> +{
> +	u16 hint = iocb->ki_write_hint;
> +
> +	if (!hint)
> +		return file_inode(iocb->ki_filp)->i_write_hint;
> +
> +	if (hint > bdev_max_write_hints(bdev))
> +		return file_inode(iocb->ki_filp)->i_write_hint;
> +
> +	if (bdev_is_partition(bdev) &&
> +	    !test_bit(hint - 1, bdev->write_hint_mask))
> +		return file_inode(iocb->ki_filp)->i_write_hint;

I would have expected an error when using an invalid stream identifier.

That of course requires telling the application how many are available
through e.g. statx as requested last time.