Re: Picking 0th namespace if it is idle

aneesh.kumar(a)linux.ibm.com (Aneesh Kumar K.V) writes: > Hi Dan, > > With the patch series to mark the namespace disabled if we have mismatch > in pfn superblock, we can endup with namespace0 marked idle/disabled. > > I am wondering why do do the below in ndctl. > > > static struct ndctl_namespace *region_get_namespace(struct ndctl_region *region) > { > struct ndctl_namespace *ndns; > > /* prefer the 0th namespace if it is idle */ > ndctl_namespace_foreach(region, ndns) > if (ndctl_namespace_get_id(ndns) == 0 > && !is_namespace_active(ndns)) > return ndns; > return ndctl_region_get_namespace_seed(region); > } > > I have a kernel patch that will create a namespace_seed even if we fail > to ename a pfn backing device. Something like below > > @@ -747,12 +752,23 @@ static void nd_region_notify_driver_action(struct nvdimm_bus *nvdimm_bus, > } > } > if (dev->parent && is_nd_region(dev->parent) && probe) { > nd_region = to_nd_region(dev->parent); > nvdimm_bus_lock(dev); > if (nd_region->ns_seed == dev) > nd_region_create_ns_seed(nd_region); > nvdimm_bus_unlock(dev); > } > + > + if (dev->parent && is_nd_region(dev->parent) && !probe && (ret == -EOPNOTSUPP)) { > + nd_region = to_nd_region(dev->parent); > + nvdimm_bus_lock(dev); > + if (nd_region->ns_seed == dev) > + nd_region_create_ns_seed(nd_region); > + nvdimm_bus_unlock(dev); > + } > + > > With that we can end up with something like the below after boot. > :/sys/bus/nd/devices/region0$ sudo ndctl list -Ni > [ > { > "dev":"namespace0.1", > "mode":"fsdax", > "map":"mem", > "size":0, > "uuid":"00000000-0000-0000-0000-000000000000", > "state":"disabled" > }, > { > "dev":"namespace0.0", > "mode":"fsdax", > "map":"mem", > "size":2147483648, > "uuid":"094e703b-4bf8-4078-ad42-50bebc03e538", > "state":"disabled" > } > ] > > namespace0.0 is the one we failed to initialize due to PAGE_SIZE > mismatch. > > We do have namespace_seed pointing to namespacece0.1 correct. But a ndtl > create-namespace will pick namespace0.0 even if we have seed file > pointing to namespacec0.1. > > > I am trying to resolve the issues related to creation of new namespaces > when we have some namespace marked disabled due to pfn_sb setting > mismatch. > > -aneesh With that ndctl namespace0.0 selection commented out, we do get pick the right idle namespace. #ndctl list -Ni [ { "dev":"namespace0.1", "mode":"fsdax", "map":"mem", "size":0, "uuid":"00000000-0000-0000-0000-000000000000", "state":"disabled" }, { "dev":"namespace0.0", "mode":"fsdax", "map":"mem", "size":2147483648, "uuid":"0c31ae4b-b053-43c7-82ff-88574e2585b0", "state":"disabled" } ] after ndctl create-namespace -s 2G -r region0 # ndctl list -Ni [ { "dev":"namespace0.2", "mode":"fsdax", "map":"mem", "size":0, "uuid":"00000000-0000-0000-0000-000000000000", "state":"disabled" }, { "dev":"namespace0.1", "mode":"fsdax", "map":"dev", "size":2130706432, "uuid":"60970059-9412-4eeb-9e7a-b314585a4da3", "align":65536, "blockdev":"pmem0.1", "supported_alignments":[ 65536 ] }, { "dev":"namespace0.0", "mode":"fsdax", "map":"mem", "size":2147483648, "uuid":"0c31ae4b-b053-43c7-82ff-88574e2585b0", "state":"disabled" } ]