Re: [PATCH v2] file-posix: fix zone write granularity assignment for zoned block devices

Stefan Hajnoczi <[email protected]> Wed, 12 Aug 2026 11:03:25 -0400

Newsgroups	gmane.comp.emulators.qemu,gmane.comp.emulators.qemu.block
Message-ID	<20260812150324.GE244786@fedora>

On Tue, Aug 11, 2026 at 03:32:36PM +0200, Niklas Cassel wrote:
> In the ZBC and ZAC specifications, the requirement is that the write
> granularity matches the physical block size.
> 
> However, in the ZNS specification, the requirement is simply that the
> write granularity matches the logical block size.
> 
> See:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a805a4fa4fa376bbc145762bb8b09caa2fa8af48
> 
> In Linux, there is a zone_write_granularity sysfs property which abstracts
> this away, so let's make use of it.
> 
> Currently, it is theoretically possible that QEMU presents an inflated
> write granularity for NVMe devices where the physical block size is larger
> than the logical block size.
> 
> Reviewed-by: Damien Le Moal <[email protected]>
> Fixes: a3c41f06d5a8 ("file-posix: add tracking of the zone write pointers")
> Signed-off-by: Niklas Cassel <[email protected]>
> ---
> Changes since v1:
> -Improved commit log.
> -Picked up tag.
> 
>  block/file-posix.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Stefan Hajnoczi <[email protected]>

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