On Sat, Sep 12, 2020 at 06:30:56AM +0100, Christoph Hellwig wrote:
On Sat, Sep 12, 2020 at 01:14:24PM +0900, Naohiro Aota wrote:
> For zoned devices you need to use bio_add_hw_page instead of so that all
> the hardware restrictions are applied. bio_add_hw_page asso gets the
> lenght limited passed as the last parameter so we won't need a separate
> check.
I think we can't use it here. This bio is built for btrfs's logical space,
so the corresponding request queue is not available here.
Technically, we can use fs_devices->lateste_bdev. But considering this bio
can map to multiple bios to multiple devices, limiting the size of this bio
under the minimum queue_max_zone_appends_sectors() among devices is
feasible.
Well, how do you then ensure the bio actually fits all the other
device limits as well? e.g. max segment size, no SG gaps policy,
etc?
Yeah, that's problematic, and I realized we could not deal with all the
restrictions in this manner. I'm reimplementing this patch basing on
bio_add_hw_page().
Regards,
