[PATCHv2 2/5] nvme: simplify passthrough bio cleanup

[Keith Busch <kbusch@meta.com>]

From: Keith Busch <kbusch@kernel.org>

Set the bio's bi_end_io to handle the cleanup so that uring_cmd doesn't
need this complex pdu->{bio,req} switchero and restore.

Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 drivers/nvme/host/ioctl.c | 26 +++++++++-----------------
 1 file changed, 9 insertions(+), 17 deletions(-)

diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index d24ea2e051564..278c57ee0db91 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -159,6 +159,11 @@ static struct request *nvme_alloc_user_request(struct request_queue *q,
 	return req;
 }
 
+static void nvme_uring_bio_end_io(struct bio *bio)
+{
+	blk_rq_unmap_user(bio);
+}
+
 static int nvme_map_user_request(struct request *req, u64 ubuffer,
 		unsigned bufflen, void __user *meta_buffer, unsigned meta_len,
 		u32 meta_seed, void **metap, struct io_uring_cmd *ioucmd,
@@ -204,6 +209,7 @@ static int nvme_map_user_request(struct request *req, u64 ubuffer,
 		*metap = meta;
 	}
 
+	bio->bi_end_io = nvme_uring_bio_end_io;
 	return ret;
 
 out_unmap:
@@ -249,8 +255,6 @@ static int nvme_submit_user_cmd(struct request_queue *q,
 	if (meta)
 		ret = nvme_finish_user_metadata(req, meta_buffer, meta,
 						meta_len, ret);
-	if (bio)
-		blk_rq_unmap_user(bio);
 	blk_mq_free_request(req);
 
 	if (effects)
@@ -443,10 +447,7 @@ struct nvme_uring_data {
  * Expect build errors if this grows larger than that.
  */
 struct nvme_uring_cmd_pdu {
-	union {
-		struct bio *bio;
-		struct request *req;
-	};
+	struct request *req;
 	u32 meta_len;
 	u32 nvme_status;
 	union {
@@ -482,8 +483,6 @@ static void nvme_uring_task_meta_cb(struct io_uring_cmd *ioucmd,
 	if (pdu->meta_len)
 		status = nvme_finish_user_metadata(req, pdu->u.meta_buffer,
 					pdu->u.meta, pdu->meta_len, status);
-	if (req->bio)
-		blk_rq_unmap_user(req->bio);
 	blk_mq_free_request(req);
 
 	io_uring_cmd_done(ioucmd, status, result, issue_flags);
@@ -494,9 +493,6 @@ static void nvme_uring_task_cb(struct io_uring_cmd *ioucmd,
 {
 	struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
 
-	if (pdu->bio)
-		blk_rq_unmap_user(pdu->bio);
-
 	io_uring_cmd_done(ioucmd, pdu->nvme_status, pdu->u.result, issue_flags);
 }
 
@@ -507,7 +503,6 @@ static enum rq_end_io_ret nvme_uring_cmd_end_io(struct request *req,
 	struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
 	void *cookie = READ_ONCE(ioucmd->cookie);
 
-	req->bio = pdu->bio;
 	if (nvme_req(req)->flags & NVME_REQ_CANCELLED)
 		pdu->nvme_status = -EINTR;
 	else
@@ -533,9 +528,6 @@ static enum rq_end_io_ret nvme_uring_cmd_end_io_meta(struct request *req,
 	struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
 	void *cookie = READ_ONCE(ioucmd->cookie);
 
-	req->bio = pdu->bio;
-	pdu->req = req;
-
 	/*
 	 * For iopoll, complete it directly.
 	 * Otherwise, move the completion to task work.
@@ -624,8 +616,8 @@ static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 			req->bio->bi_opf |= REQ_POLLED;
 		}
 	}
-	/* to free bio on completion, as req->bio will be null at that time */
-	pdu->bio = req->bio;
+
+	pdu->req = req;
 	pdu->meta_len = d.metadata_len;
 	req->end_io_data = ioucmd;
 	if (pdu->meta_len) {
-- 
2.34.1