libnvdimm: fix mishandled nvdimm_clear_poison() return value

Colin, via static analysis, reports that the length could be negative
from nvdimm_clear_poison() in the error case. There was a similar
problem with commit 0a3f27b9a6a8 "libnvdimm, namespace: avoid multiple
sector calculations" that I noticed when merging the for-4.10/libnvdimm
topic branch into libnvdimm-for-next, but I missed this one. Fix both of
them to the following procedure:

* if we clear a block's worth of media, clear that many blocks in
  badblocks

* if we clear less than the requested size of the transfer return an
  error

* always invalidate cache after any non-error / non-zero
  nvdimm_clear_poison result

Fixes: 82bf1037f2ca ("libnvdimm: check and clear poison before writing to pmem")
Fixes: 0a3f27b9a6a8 ("libnvdimm, namespace: avoid multiple sector calculations")
Cc: Fabian Frederick <fabf@skynet.be>
Cc: Dave Jiang <dave.jiang@intel.com>
Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 5 insertions, 4 deletions

diff --git a/drivers/nvdimm/claim.c b/drivers/nvdimm/claim.c
index 97d1772774a8..b3323c0697f6 100644
--- a/drivers/nvdimm/claim.c
+++ b/drivers/nvdimm/claim.c
@@ -247,12 +247,13 @@ static int nsio_rw_bytes(struct nd_namespace_common *ndns,
 			long cleared;
 
 			cleared = nvdimm_clear_poison(&ndns->dev, offset, size);
-			if (cleared != size) {
-				size = cleared;
+			if (cleared < size)
 				rc = -EIO;
+			if (cleared > 0 && cleared / 512) {
+				cleared /= 512;
+				badblocks_clear(&nsio->bb, sector, cleared);
 			}
-
-			badblocks_clear(&nsio->bb, sector, cleared >> 9);
+			invalidate_pmem(nsio->addr + offset, size);
 		} else
 			rc = -EIO;
 	}