Re: [PATCH v2 15/17] libnvdimm: Set numa_node to NVDIMM devices

[Williams, Dan J]

On Thu, 2015-06-25 at 16:55 -0600, Toshi Kani wrote:
> On Thu, 2015-06-25 at 15:34 -0700, Dan Williams wrote:
> > On Thu, Jun 25, 2015 at 3:11 PM, Toshi Kani <toshi.kani@xxxxxx> wrote:
> > > On Thu, 2015-06-25 at 15:00 -0700, Dan Williams wrote:
> > > Yes, I see no problem with bound BTTs and their device files.  So, how
> > > do we bind BTT with this new version?
> > >
> > 
> > # cd /sys/bus/nd/devices
> > # uuidgen > btt6/uuid
> > # echo 4096 > btt6/sector_size
> > # echo namespace6.0 > btt6/namespace
> > # echo namespace6.0 > ../drivers/nd_pmem/unbind
> > # echo btt6 > ../drivers/nd_pmem/bind
> > 
> > After reboot, when the system sees namespace6.0 again it will notice
> > the btt instance and attach bttX instead.  The net effect is that now
> > you'll only ever have /dev/pmem6 or /dev/pmem6s, never both at the
> > same time that was a side effect of the stacking approach.
> > 
> > I'll post the patch that updates libndctl and the unit tests shortly
> 
> Maybe I am missing something, but I am getting errors on my system.  (I
> used btt0 since there is no btt6.)
> 
> # cat bind.sh
> set -x
> cd /sys/bus/nd/devices
> uuidgen > btt0/uuid
> echo 4096 > btt0/sector_size
> echo namespace0.0 > btt0/namespace
> echo namespace0.0 > ../drivers/nd_pmem/unbind
> echo btt0 > ../drivers/nd_pmem/bind
> 
> # sh bind.sh
> + cd /sys/bus/nd/devices
> + uuidgen
> + echo 4096
> + echo namespace0.0
> bind.sh: line 6: echo: write error: Device or resource busy
> + echo namespace0.0
> bind.sh: line 7: echo: write error: No such device
> + echo btt0
> bind.sh: line 8: echo: write error: No such device
> 
> # dmesg
>  :
> [12513.839162] nd btt0: uuid_store: result: 0 wrote:
> b32cd195-9aae-4c54-a5ac-49adb50a8a98
> [12513.880286] nd btt0: sector_size_store: result: 0 wrote: 4096
> [12513.909494] nd btt0: namespace0.0 already claimed
> [12513.933364] nd btt0: namespace_store: result: -16 wrote: namespace0.0
> [12513.966808]  ndbus0: nd_pmem.probe(btt0) = -19
> 

So this turned out to be a perfect example of why we might want to have
the region-id in the btt device name just like namespaces, because btt0
was actually bound to namespace4.0 on Toshi's system.  The following
update, that I will fold in to the series, fixes this.  Note that the
association of btt id to to namespace is still non-deterministic.  I.e.
btt0.1 could be assigned as the btt for namespace0.0, but at least when
looking at /sys/bus/nd/devices it will be clear which btts belong to
which regions.

# ls /sys/bus/nd/devices
btt0.0  btt3.0  btt6.0        namespace2.0  namespace5.0  nmem1  nmem4    region2  region5
btt1.0  btt4.0  namespace0.0  namespace3.0  namespace6.0  nmem2  region0  region3  region6
btt2.0  btt5.0  namespace1.0  namespace4.0  nmem0         nmem3  region1  region4


8<------------
diff --git a/drivers/nvdimm/btt_devs.c b/drivers/nvdimm/btt_devs.c
index 2dfb529f4d35..6ac8c0fea3ec 100644
--- a/drivers/nvdimm/btt_devs.c
+++ b/drivers/nvdimm/btt_devs.c
@@ -21,8 +21,6 @@
 #include "btt.h"
 #include "nd.h"
 
-static DEFINE_IDA(btt_ida);
-
 static void __nd_btt_detach_ndns(struct nd_btt *nd_btt)
 {
 	struct nd_namespace_common *ndns = nd_btt->ndns;
@@ -75,11 +73,12 @@ static bool nd_btt_attach_ndns(struct nd_btt *nd_btt,
 
 static void nd_btt_release(struct device *dev)
 {
+	struct nd_region *nd_region = to_nd_region(dev->parent);
 	struct nd_btt *nd_btt = to_nd_btt(dev);
 
 	dev_dbg(dev, "%s\n", __func__);
 	nd_btt_detach_ndns(nd_btt);
-	ida_simple_remove(&btt_ida, nd_btt->id);
+	ida_simple_remove(&nd_region->btt_ida, nd_btt->id);
 	kfree(nd_btt->uuid);
 	kfree(nd_btt);
 }
@@ -309,7 +308,7 @@ static struct device *__nd_btt_create(struct nd_region *nd_region,
 	if (!nd_btt)
 		return NULL;
 
-	nd_btt->id = ida_simple_get(&btt_ida, 0, 0, GFP_KERNEL);
+	nd_btt->id = ida_simple_get(&nd_region->btt_ida, 0, 0, GFP_KERNEL);
 	if (nd_btt->id < 0) {
 		kfree(nd_btt);
 		return NULL;
@@ -320,7 +319,7 @@ static struct device *__nd_btt_create(struct nd_region *nd_region,
 		uuid = kmemdup(uuid, 16, GFP_KERNEL);
 	nd_btt->uuid = uuid;
 	dev = &nd_btt->dev;
-	dev_set_name(dev, "btt%d", nd_btt->id);
+	dev_set_name(dev, "btt%d.%d", nd_region->id, nd_btt->id);
 	dev->parent = &nd_region->dev;
 	dev->type = &nd_btt_device_type;
 	dev->groups = nd_btt_attribute_groups;
diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
index 72c26461835d..c41f53e74277 100644
--- a/drivers/nvdimm/nd.h
+++ b/drivers/nvdimm/nd.h
@@ -91,6 +91,7 @@ struct nd_percpu_lane {
 struct nd_region {
 	struct device dev;
 	struct ida ns_ida;
+	struct ida btt_ida;
 	struct device *ns_seed;
 	struct device *btt_seed;
 	u16 ndr_mappings;
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index 55b424f6ba0d..a5233422f9dc 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -738,6 +738,7 @@ static struct nd_region *nd_region_create(struct nvdimm_bus *nvdimm_bus,
 	nd_region->ro = ro;
 	nd_region->numa_node = ndr_desc->numa_node;
 	ida_init(&nd_region->ns_ida);
+	ida_init(&nd_region->btt_ida);
 	dev = &nd_region->dev;
 	dev_set_name(dev, "region%d", nd_region->id);
 	dev->parent = &nvdimm_bus->dev;