libnvdimm, pmem: nvdimm_read_bytes() badblocks support

Support badblock checking in all the pmem read paths that do not go
through the block layer.  This protects info block reads (btt or pfn) as
well as data reads to a pmem namespace via a btt instance.
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

drivers/nvdimm/pmem.c

@@ -229,6 +229,7 @@ static int pmem_attach_disk(struct device *dev,
 	disk->driverfs_dev = dev;
 	set_capacity(disk, (pmem->size - pmem->data_offset) / 512);
 	pmem->pmem_disk = disk;
+	devm_exit_badblocks(dev, &pmem->bb);
 	if (devm_init_badblocks(dev, &pmem->bb))
 		return -ENOMEM;
 	nvdimm_namespace_add_poison(ndns, &pmem->bb, pmem->data_offset);
@@ -250,9 +251,13 @@ static int pmem_rw_bytes(struct nd_namespace_common *ndns,
 		return -EFAULT;
 	}
 
-	if (rw == READ)
+	if (rw == READ) {
+		unsigned int sz_align = ALIGN(size + (offset & (512 - 1)), 512);
+
+		if (unlikely(is_bad_pmem(&pmem->bb, offset / 512, sz_align)))
+			return -EIO;
 		memcpy_from_pmem(buf, pmem->virt_addr + offset, size);
-	else {
+	} else {
 		memcpy_to_pmem(pmem->virt_addr + offset, buf, size);
 		wmb_pmem();
 	}
@@ -427,6 +432,9 @@ static int nd_pmem_probe(struct device *dev)
 	pmem->ndns = ndns;
 	dev_set_drvdata(dev, pmem);
 	ndns->rw_bytes = pmem_rw_bytes;
+	if (devm_init_badblocks(dev, &pmem->bb))
+		return -ENOMEM;
+	nvdimm_namespace_add_poison(ndns, &pmem->bb, 0);
 
 	if (is_nd_btt(dev))
 		return nvdimm_namespace_attach_btt(ndns);