nvme: introduce struct nvme_request

This adds a shared per-request structure for all NVMe I/O.  This structure
is embedded as the first member in all NVMe transport drivers request
private data and allows to implement common functionality between the
drivers.

The first use is to replace the current abuse of the SCSI command
passthrough fields in struct request for the NVMe command passthrough,
but it will grow a field more fields to allow implementing things
like common abort handlers in the future.

The passthrough commands are handled by having a pointer to the SQE
(struct nvme_command) in struct nvme_request, and the union of the
possible result fields, which had to be turned from an anonymous
into a named union for that purpose.  This avoids having to pass
a reference to a full CQE around and thus makes checking the result
a lot more lightweight.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index 7676557ce357..18ce9f7cc881 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -949,11 +949,11 @@ struct nvme_completion {
 	/*
 	 * Used by Admin and Fabrics commands to return data:
 	 */
-	union {
-		__le16	result16;
-		__le32	result;
-		__le64	result64;
-	};
+	union nvme_result {
+		__le16	u16;
+		__le32	u32;
+		__le64	u64;
+	} result;
 	__le16	sq_head;	/* how much of this queue may be reclaimed */
 	__le16	sq_id;		/* submission queue that generated this entry */
 	__u16	command_id;	/* of the command which completed */