pmem: report error on clear poison failure

ACPI Clear Uncorrectable Error DSM function may fail or may be
unsupported on a platform.  pmem_clear_poison() returns without clearing
badblocks in such cases.  This failure is detected at the next read
(-EIO).

This behavior can lead to an issue when user keeps writing but does not
read immediately.  For instance, flight recorder file may be only read
when it is necessary for troubleshooting.

Change pmem_do_bvec() and pmem_clear_poison() to return -EIO so that
filesystem can log an error message on a write error.

Cc: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 42b3a82..2461843 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -47,7 +47,7 @@
 	return to_nd_region(to_dev(pmem)->parent);
 }
 
-static void pmem_clear_poison(struct pmem_device *pmem, phys_addr_t offset,
+static int pmem_clear_poison(struct pmem_device *pmem, phys_addr_t offset,
 		unsigned int len)
 {
 	struct device *dev = to_dev(pmem);
@@ -62,8 +62,12 @@
 				__func__, (unsigned long long) sector,
 				cleared / 512, cleared / 512 > 1 ? "s" : "");
 		badblocks_clear(&pmem->bb, sector, cleared / 512);
+	} else {
+		return -EIO;
 	}
+
 	invalidate_pmem(pmem->virt_addr + offset, len);
+	return 0;
 }
 
 static void write_pmem(void *pmem_addr, struct page *page,
@@ -123,7 +127,7 @@
 		flush_dcache_page(page);
 		write_pmem(pmem_addr, page, off, len);
 		if (unlikely(bad_pmem)) {
-			pmem_clear_poison(pmem, pmem_off, len);
+			rc = pmem_clear_poison(pmem, pmem_off, len);
 			write_pmem(pmem_addr, page, off, len);
 		}
 	}