[PATCH for-next v2 4/4] nvme: wire up fixed buffer support for nvme passthrough

[Kanchan Joshi]

if io_uring sends passthrough command with IO_URING_F_FIXEDBUFS flag,
use the pre-registered buffer to form the bio.
While at it modify nvme_submit_user_cmd to take ubuffer as plain integer
argument, and do away with nvme_to_user_ptr conversion in callers.

Signed-off-by: Anuj Gupta <anuj20.g at samsung.com>
Signed-off-by: Kanchan Joshi <joshi.k at samsung.com>
---
 drivers/nvme/host/ioctl.c | 38 ++++++++++++++++++++++++++------------
 1 file changed, 26 insertions(+), 12 deletions(-)

diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index 7756b439a688..5a4649293e86 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -65,10 +65,11 @@ static int nvme_finish_user_metadata(struct request *req, void __user *ubuf,
 }
 
 static struct request *nvme_alloc_user_request(struct request_queue *q,
-		struct nvme_command *cmd, void __user *ubuffer,
+		struct nvme_command *cmd, u64 ubuffer,
 		unsigned bufflen, void __user *meta_buffer, unsigned meta_len,
 		u32 meta_seed, void **metap, unsigned timeout, bool vec,
-		blk_opf_t rq_flags, blk_mq_req_flags_t blk_flags)
+		blk_opf_t rq_flags, blk_mq_req_flags_t blk_flags,
+		struct io_uring_cmd *ioucmd, bool fixedbufs)
 {
 	bool write = nvme_is_write(cmd);
 	struct nvme_ns *ns = q->queuedata;
@@ -89,14 +90,27 @@ static struct request *nvme_alloc_user_request(struct request_queue *q,
 
 	if (ubuffer && bufflen) {
 		if (!vec)
-			ret = blk_rq_map_user(q, req, NULL, ubuffer, bufflen,
-				GFP_KERNEL);
+			if (fixedbufs) {
+				struct iov_iter iter;
+
+				ret = io_uring_cmd_import_fixed(ubuffer,
+						bufflen, rq_data_dir(req),
+						&iter, ioucmd);
+				if (ret < 0)
+					goto out;
+				ret = blk_rq_map_user_bvec(req, &iter);
+			} else {
+				ret = blk_rq_map_user(q, req, NULL,
+						nvme_to_user_ptr(ubuffer),
+						bufflen, GFP_KERNEL);
+			}
 		else {
 			struct iovec fast_iov[UIO_FASTIOV];
 			struct iovec *iov = fast_iov;
 			struct iov_iter iter;
 
-			ret = import_iovec(rq_data_dir(req), ubuffer, bufflen,
+			ret = import_iovec(rq_data_dir(req),
+					nvme_to_user_ptr(ubuffer), bufflen,
 					UIO_FASTIOV, &iov, &iter);
 			if (ret < 0)
 				goto out;
@@ -132,7 +146,7 @@ static struct request *nvme_alloc_user_request(struct request_queue *q,
 }
 
 static int nvme_submit_user_cmd(struct request_queue *q,
-		struct nvme_command *cmd, void __user *ubuffer,
+		struct nvme_command *cmd, u64 ubuffer,
 		unsigned bufflen, void __user *meta_buffer, unsigned meta_len,
 		u32 meta_seed, u64 *result, unsigned timeout, bool vec)
 {
@@ -142,7 +156,7 @@ static int nvme_submit_user_cmd(struct request_queue *q,
 	int ret;
 
 	req = nvme_alloc_user_request(q, cmd, ubuffer, bufflen, meta_buffer,
-			meta_len, meta_seed, &meta, timeout, vec, 0, 0);
+			meta_len, meta_seed, &meta, timeout, vec, 0, 0, NULL, 0);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
@@ -220,7 +234,7 @@ static int nvme_submit_io(struct nvme_ns *ns, struct nvme_user_io __user *uio)
 	c.rw.appmask = cpu_to_le16(io.appmask);
 
 	return nvme_submit_user_cmd(ns->queue, &c,
-			nvme_to_user_ptr(io.addr), length,
+			io.addr, length,
 			metadata, meta_len, lower_32_bits(io.slba), NULL, 0,
 			false);
 }
@@ -274,7 +288,7 @@ static int nvme_user_cmd(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 		timeout = msecs_to_jiffies(cmd.timeout_ms);
 
 	status = nvme_submit_user_cmd(ns ? ns->queue : ctrl->admin_q, &c,
-			nvme_to_user_ptr(cmd.addr), cmd.data_len,
+			cmd.addr, cmd.data_len,
 			nvme_to_user_ptr(cmd.metadata), cmd.metadata_len,
 			0, &result, timeout, false);
 
@@ -320,7 +334,7 @@ static int nvme_user_cmd64(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 		timeout = msecs_to_jiffies(cmd.timeout_ms);
 
 	status = nvme_submit_user_cmd(ns ? ns->queue : ctrl->admin_q, &c,
-			nvme_to_user_ptr(cmd.addr), cmd.data_len,
+			cmd.addr, cmd.data_len,
 			nvme_to_user_ptr(cmd.metadata), cmd.metadata_len,
 			0, &cmd.result, timeout, vec);
 
@@ -457,11 +471,11 @@ static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 		rq_flags |= REQ_POLLED;
 
 retry:
-	req = nvme_alloc_user_request(q, &c, nvme_to_user_ptr(d.addr),
+	req = nvme_alloc_user_request(q, &c, d.addr,
 			d.data_len, nvme_to_user_ptr(d.metadata),
 			d.metadata_len, 0, &meta, d.timeout_ms ?
 			msecs_to_jiffies(d.timeout_ms) : 0, vec, rq_flags,
-			blk_flags);
+			blk_flags, ioucmd, issue_flags & IO_URING_F_FIXEDBUFS);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 	req->end_io = nvme_uring_cmd_end_io;
-- 
2.25.1