On Wed, 23 Aug 2023 at 10:24, Sam Li <faithilike...@gmail.com> wrote: > > Hi Stefan, > > Stefan Hajnoczi <stefa...@gmail.com> 于2023年8月23日周三 21:26写道： > > > > Hi Sam and Klaus, > > Val is adding nvme-io_uring ZNS support to libblkio > > (https://gitlab.com/libblkio/libblkio/-/merge_requests/221) and asked > > how to test the size of the last zone when the namespace's total size > > is not a multiple of the zone size. > > I think a zone report operation can do the trick. Given zone configs, > the size of last zone should be [size - (nr_zones - 1) * zone_size]. > Reporting last zone on such devices tells whether the value is > correct.
In nvme_ns_zoned_check_calc_geometry() the number of zones is rounded down: ns->num_zones = le64_to_cpu(ns->id_ns.nsze) / ns->zone_size; Afterwards nsze is recalculated as follows: ns->id_ns.nsze = cpu_to_le64(ns->num_zones * ns->zone_size); I interpret this to mean that when the namespace's total size is not a multiple of the zone size, then the last part will be ignored and not exposed as a zone. > > > > > My understanding is that the zoned storage model allows the last zone > > to be smaller than the zone size in this case. However, the NVMe ZNS > > emulation code in QEMU makes all zones a multiple of the zone size. I > > think QEMU cannot be used for this test case at the moment. > > > > Are there any plans to allow the last zone to have a different size? > > Maybe Sam's qcow2 work will allow this? > > Yes, the zone report in qcow2 allows smaller last zone. > Please let me know if there is any problem. Great. Val can try your qcow2 patches and see if that allows her to test last zone size != zone_size. Thanks, Stefan
