[PATCH 5.4] nvme: fix metadata handling in nvme-passthrough

[Hagar Hemdan <hagarhem@amazon.com>]

From: Puranjay Mohan <pjy@amazon.com>

[ Upstream commit 7c2fd76048e95dd267055b5f5e0a48e6e7c81fd9 ]

On an NVMe namespace that does not support metadata, it is possible to
send an IO command with metadata through io-passthru. This allows issues
like [1] to trigger in the completion code path.
nvme_map_user_request() doesn't check if the namespace supports metadata
before sending it forward. It also allows admin commands with metadata to
be processed as it ignores metadata when bdev == NULL and may report
success.

Reject an IO command with metadata when the NVMe namespace doesn't
support it and reject an admin command if it has metadata.

[1] https://lore.kernel.org/all/mb61pcylvnym8.fsf@amazon.com/

Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Puranjay Mohan <pjy@amazon.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
[ Move the changes from nvme_map_user_request() to nvme_submit_user_cmd()
  to make it work on 5.4 ]
Signed-off-by: Hagar Hemdan <hagarhem@amazon.com>
---
 drivers/nvme/host/core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 0676637e1eab..a841fd4929ad 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -921,11 +921,16 @@ static int nvme_submit_user_cmd(struct request_queue *q,
 	bool write = nvme_is_write(cmd);
 	struct nvme_ns *ns = q->queuedata;
 	struct gendisk *disk = ns ? ns->disk : NULL;
+	bool supports_metadata = disk && blk_get_integrity(disk);
+	bool has_metadata = meta_buffer && meta_len;
 	struct request *req;
 	struct bio *bio = NULL;
 	void *meta = NULL;
 	int ret;
 
+	if (has_metadata && !supports_metadata)
+		return -EINVAL;
+
 	req = nvme_alloc_request(q, cmd, 0, NVME_QID_ANY);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
@@ -940,7 +945,7 @@ static int nvme_submit_user_cmd(struct request_queue *q,
 			goto out;
 		bio = req->bio;
 		bio->bi_disk = disk;
-		if (disk && meta_buffer && meta_len) {
+		if (has_metadata) {
 			meta = nvme_add_user_metadata(bio, meta_buffer, meta_len,
 					meta_seed, write);
 			if (IS_ERR(meta)) {
-- 
2.40.1