[PATCH] libnvdimm: Fix __nd_ioctl() to check error in cmd_rc

[Toshi Kani <toshi.kani@xxxxxxx>]

ndctl zero-labels completes with a large number of zeroed nmems when
it fails to do zeroing on a protected NVDIMM.

  # ndctl zero-labels nmem1
  zeroed 65504 nmems

When an ACPI call completes with error, xlat_status() called from
acpi_nfit_ctl() sets error to *cmd_rc.  __nd_ioctl(), however, does
not check this error and returns with success.

Fix __nd_ioctl() to check this error in cmd_rc.

Fixes: 006358b35c73a ("libnvdimm: add support for clear poison list and badblocks for device dax")
Reported-by: Robert Elliott <elliott@xxxxxxx>
Signed-off-by: Toshi Kani <toshi.kani@xxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Vishal Verma <vishal.l.verma@xxxxxxxxx>
Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
---
 drivers/nvdimm/bus.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
index f1fb39921236..af12817d8a02 100644
--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -1050,6 +1050,10 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm,
 	rc = nd_desc->ndctl(nd_desc, nvdimm, cmd, buf, buf_len, &cmd_rc);
 	if (rc < 0)
 		goto out_unlock;
+	if (cmd_rc < 0) {
+		rc = cmd_rc;
+		goto out_unlock;
+	}
 
 	if (!nvdimm && cmd == ND_CMD_CLEAR_ERROR && cmd_rc >= 0) {
 		struct nd_cmd_clear_error *clear_err = buf;