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, which leads to a silent data
corruption.

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

Signed-off-by: Toshi Kani <toshi.k...@hpe.com>
Cc: Dan Williams <dan.j.willi...@intel.com>
Cc: Vishal Verma <vishal.l.ve...@intel.com>
---
 drivers/nvdimm/pmem.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

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 @@ static struct nd_region *to_region(struct pmem_device *pmem)
        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 @@ static void pmem_clear_poison(struct pmem_device *pmem, 
phys_addr_t offset,
                                __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 @@ static int pmem_do_bvec(struct pmem_device *pmem, struct 
page *page,
                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);
                }
        }

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