[PATCH 2/4] nvme: report synchronous passthrough copyback failures

[王 颖杰]

nvme_submit_user_cmd() discards the return from blk_rq_unmap_user().
For a successful unaligned READ, a failed bounce-buffer copy can
therefore leave the destination unchanged while the ioctl still reports
success.

Keep the real controller status for nvme_passthru_end(), then return the
copyback error only when the command itself succeeded.

A one-block READ into an unaligned PROT_NONE destination returned false
success in 20/20 runs before this change.  It returned -EFAULT in 20/20
runs afterward, while writable controls continued to succeed.

Fixes: d29ec8241c10 ("nvme: submit internal commands through the block layer")
Cc: stable at vger.kernel.org
Assisted-by: LLM
Signed-off-by: Yingjie Wang <x-professor at outlook.com>
---
 drivers/nvme/host/ioctl.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index e45572bc87d..9b830641a5b 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -200,7 +200,7 @@ static int nvme_submit_user_cmd(struct request_queue *q,
 	struct request *req;
 	struct bio *bio;
 	u32 effects;
-	int ret;
+	int ret, unmap_ret = 0;
 
 	req = nvme_alloc_user_request(q, cmd, 0, 0);
 	if (IS_ERR(req))
@@ -226,7 +226,9 @@ static int nvme_submit_user_cmd(struct request_queue *q,
 	if (effects)
 		nvme_passthru_end(ctrl, ns, effects, cmd, ret);
 	if (bio)
-		blk_rq_unmap_user(bio);
+		unmap_ret = blk_rq_unmap_user(bio);
+	if (!ret)
+		ret = unmap_ret;
 	return ret;
 
 out_free_req:
-- 
2.43.0