nvme: use struct group for generic command dwords

This will allow the trace event to know the full size of the data
intended to be copied and silence read overflow checks.

Reported-by: John Garry <john.garry@huawei.com>
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/trace.h

@@ -69,7 +69,7 @@ TRACE_EVENT(nvme_setup_cmd,
 		__entry->metadata = !!blk_integrity_rq(req);
 		__entry->fctype = cmd->fabrics.fctype;
 		__assign_disk_name(__entry->disk, req->q->disk);
-		memcpy(__entry->cdw10, &cmd->common.cdw10,
+		memcpy(__entry->cdw10, &cmd->common.cdws,
 			sizeof(__entry->cdw10));
 	    ),
 	    TP_printk("nvme%d: %sqid=%d, cmdid=%u, nsid=%u, flags=0x%x, meta=0x%x, cmd=(%s %s)",

include/linux/nvme.h

@@ -906,12 +906,14 @@ struct nvme_common_command {
 	__le32			cdw2[2];
 	__le64			metadata;
 	union nvme_data_ptr	dptr;
+	struct_group(cdws,
 	__le32			cdw10;
 	__le32			cdw11;
 	__le32			cdw12;
 	__le32			cdw13;
 	__le32			cdw14;
 	__le32			cdw15;
+	);
 };
 
 struct nvme_rw_command {