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, 15 insertions, 1 deletions

diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index d47f5a5d18c7..5e64957a9b96 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -79,6 +79,20 @@ enum nvme_quirks {
 	NVME_QUIRK_DELAY_BEFORE_CHK_RDY		= (1 << 3),
 };
 
+/*
+ * Common request structure for NVMe passthrough.  All drivers must have
+ * this structure as the first member of their request-private data.
+ */
+struct nvme_request {
+	struct nvme_command	*cmd;
+	union nvme_result	result;
+};
+
+static inline struct nvme_request *nvme_req(struct request *req)
+{
+	return blk_mq_rq_to_pdu(req);
+}
+
 /* The below value is the specific amount of delay needed before checking
  * readiness in case of the PCI_DEVICE(0x1c58, 0x0003), which needs the
  * NVME_QUIRK_DELAY_BEFORE_CHK_RDY quirk enabled. The value (in ms) was
@@ -278,7 +292,7 @@ int nvme_setup_cmd(struct nvme_ns *ns, struct request *req,
 int nvme_submit_sync_cmd(struct request_queue *q, struct nvme_command *cmd,
 		void *buf, unsigned bufflen);
 int __nvme_submit_sync_cmd(struct request_queue *q, struct nvme_command *cmd,
-		struct nvme_completion *cqe, void *buffer, unsigned bufflen,
+		union nvme_result *result, void *buffer, unsigned bufflen,
 		unsigned timeout, int qid, int at_head, int flags);
 int nvme_submit_user_cmd(struct request_queue *q, struct nvme_command *cmd,
 		void __user *ubuffer, unsigned bufflen, u32 *result,