libnvdimm: write pmem label set

After 'uuid', 'size', and optionally 'alt_name' have been set to valid
values the labels on the dimms can be updated.

Write procedure is:
1/ Allocate and write new labels in the "next" index
2/ Free the old labels in the working copy
3/ Write the bitmap and the label space on the dimm
4/ Write the index to make the update valid

Label ranges directly mirror the dpa resource values for the given
label_id of the namespace.

Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Neil Brown <neilb@suse.de>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 72 insertions, 11 deletions

diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index ad0ec09ca40f..546e77e122fd 100644
--- a/drivers/nvdimm/namespace_devs.c
+++ b/drivers/nvdimm/namespace_devs.c
@@ -149,20 +149,53 @@ static resource_size_t nd_namespace_blk_size(struct nd_namespace_blk *nsblk)
         return size;
 }
 
+static int nd_namespace_label_update(struct nd_region *nd_region,
+                struct device *dev)
+{
+        dev_WARN_ONCE(dev, dev->driver,
+                        "namespace must be idle during label update\n");
+        if (dev->driver)
+                return 0;
+
+        /*
+         * Only allow label writes that will result in a valid namespace
+         * or deletion of an existing namespace.
+         */
+        if (is_namespace_pmem(dev)) {
+                struct nd_namespace_pmem *nspm = to_nd_namespace_pmem(dev);
+                struct resource *res = &nspm->nsio.res;
+                resource_size_t size = resource_size(res);
+
+                if (size == 0 && nspm->uuid)
+                        /* delete allocation */;
+                else if (!nspm->uuid)
+                        return 0;
+
+                return nd_pmem_namespace_label_update(nd_region, nspm, size);
+        } else if (is_namespace_blk(dev)) {
+                /* TODO: implement blk labels */
+                return 0;
+        } else
+                return -ENXIO;
+}
+
 static ssize_t alt_name_store(struct device *dev,
                 struct device_attribute *attr, const char *buf, size_t len)
 {
+        struct nd_region *nd_region = to_nd_region(dev->parent);
         ssize_t rc;
 
         device_lock(dev);
         nvdimm_bus_lock(dev);
         wait_nvdimm_bus_probe_idle(dev);
         rc = __alt_name_store(dev, buf, len);
+        if (rc >= 0)
+                rc = nd_namespace_label_update(nd_region, dev);
         dev_dbg(dev, "%s: %s(%zd)\n", __func__, rc < 0 ? "fail " : "", rc);
         nvdimm_bus_unlock(dev);
         device_unlock(dev);
 
-        return rc;
+        return rc < 0 ? rc : len;
 }
 
 static ssize_t alt_name_show(struct device *dev,
@@ -709,6 +742,7 @@ static ssize_t __size_store(struct device *dev, unsigned long long val)
 static ssize_t size_store(struct device *dev,
                 struct device_attribute *attr, const char *buf, size_t len)
 {
+        struct nd_region *nd_region = to_nd_region(dev->parent);
         unsigned long long val;
         u8 **uuid = NULL;
         int rc;
@@ -721,6 +755,8 @@ static ssize_t size_store(struct device *dev,
         nvdimm_bus_lock(dev);
         wait_nvdimm_bus_probe_idle(dev);
         rc = __size_store(dev, val);
+        if (rc >= 0)
+                rc = nd_namespace_label_update(nd_region, dev);
 
         if (is_namespace_pmem(dev)) {
                 struct nd_namespace_pmem *nspm = to_nd_namespace_pmem(dev);
@@ -744,7 +780,7 @@ static ssize_t size_store(struct device *dev,
         nvdimm_bus_unlock(dev);
         device_unlock(dev);
 
-        return rc ? rc : len;
+        return rc < 0 ? rc : len;
 }
 
 static ssize_t size_show(struct device *dev,
@@ -804,17 +840,34 @@ static int namespace_update_uuid(struct nd_region *nd_region,
         u32 flags = is_namespace_blk(dev) ? NSLABEL_FLAG_LOCAL : 0;
         struct nd_label_id old_label_id;
         struct nd_label_id new_label_id;
-        int i, rc;
+        int i;
 
-        rc = nd_is_uuid_unique(dev, new_uuid) ? 0 : -EINVAL;
-        if (rc) {
-                kfree(new_uuid);
-                return rc;
-        }
+        if (!nd_is_uuid_unique(dev, new_uuid))
+                return -EINVAL;
 
         if (*old_uuid == NULL)
                 goto out;
 
+        /*
+         * If we've already written a label with this uuid, then it's
+         * too late to rename because we can't reliably update the uuid
+         * without losing the old namespace.  Userspace must delete this
+         * namespace to abandon the old uuid.
+         */
+        for (i = 0; i < nd_region->ndr_mappings; i++) {
+                struct nd_mapping *nd_mapping = &nd_region->mapping[i];
+
+                /*
+                 * This check by itself is sufficient because old_uuid
+                 * would be NULL above if this uuid did not exist in the
+                 * currently written set.
+                 *
+                 * FIXME: can we delete uuid with zero dpa allocated?
+                 */
+                if (nd_mapping->labels)
+                        return -EBUSY;
+        }
+
         nd_label_gen_id(&old_label_id, *old_uuid, flags);
         nd_label_gen_id(&new_label_id, new_uuid, flags);
         for (i = 0; i < nd_region->ndr_mappings; i++) {
@@ -858,12 +911,16 @@ static ssize_t uuid_store(struct device *dev,
         rc = nd_uuid_store(dev, &uuid, buf, len);
         if (rc >= 0)
                 rc = namespace_update_uuid(nd_region, dev, uuid, ns_uuid);
+        if (rc >= 0)
+                rc = nd_namespace_label_update(nd_region, dev);
+        else
+                kfree(uuid);
         dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
                         rc, buf, buf[len - 1] == '\n' ? "" : "\n");
         nvdimm_bus_unlock(dev);
         device_unlock(dev);
 
-        return rc ? rc : len;
+        return rc < 0 ? rc : len;
 }
 static DEVICE_ATTR_RW(uuid);
 
@@ -907,6 +964,7 @@ static ssize_t sector_size_store(struct device *dev,
                 struct device_attribute *attr, const char *buf, size_t len)
 {
         struct nd_namespace_blk *nsblk = to_nd_namespace_blk(dev);
+        struct nd_region *nd_region = to_nd_region(dev->parent);
         ssize_t rc;
 
         if (!is_namespace_blk(dev))
@@ -916,8 +974,11 @@ static ssize_t sector_size_store(struct device *dev,
         nvdimm_bus_lock(dev);
         rc = nd_sector_size_store(dev, buf, &nsblk->lbasize,
                         ns_lbasize_supported);
-        dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
-                        rc, buf, buf[len - 1] == '\n' ? "" : "\n");
+        if (rc >= 0)
+                rc = nd_namespace_label_update(nd_region, dev);
+        dev_dbg(dev, "%s: result: %zd %s: %s%s", __func__,
+                        rc, rc < 0 ? "tried" : "wrote", buf,
+                        buf[len - 1] == '\n' ? "" : "\n");
         nvdimm_bus_unlock(dev);
         device_unlock(dev);