linux-kernel - [PATCH] pmem: report error on clear poison failure

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Date:   Thu, 13 Oct 2016 09:54:21 -0600
From:   Toshi Kani <toshi.kani@....com>
To:     dan.j.williams@...el.com
Cc:     vishal.l.verma@...el.com, linux-nvdimm@...ts.01.org,
        linux-kernel@...r.kernel.org, Toshi Kani <toshi.kani@....com>
Subject: [PATCH] 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, 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.kani@....com>
Cc: Dan Williams <dan.j.williams@...el.com>
Cc: Vishal Verma <vishal.l.verma@...el.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);
 		}
 	}