[PATCHv10 4/9] block: allow ability to limit partition write hints

[Christoph Hellwig]

On Tue, Oct 29, 2024 at 08:19:17AM -0700, Keith Busch wrote:
> From: Keith Busch <kbusch at kernel.org>
> 
> When multiple partitions are used, you may want to enforce different
> subsets of the available write hints for each partition. Provide a
> bitmap attribute of the available write hints, and allow an admin to
> write a different mask to set the partition's allowed write hints.

This still offers all hints to all partitions by default, which still
breaks all use cases where you have actual users of the stream separation
on multiple paritions.

Please assign either all resources to the first partition and none to
the others (probably the easiest and useful for the most common use
case) or split it evenly.

Note that the bdev_max_streams value also needs to be adjusted to only
return the number of streams actually available to a partition.