nvme: add vectored-io support for uring-cmd

wire up support for async passthru that takes an array of buffers (using
iovec). Exposed via a new op NVME_URING_CMD_IO_VEC. Same 'struct
nvme_uring_cmd' is to be used with -

1. cmd.addr as base address of user iovec array
2. cmd.data_len as count of iovec array elements
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220511054750.20432-6-joshi.k@samsung.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/host/ioctl.c

@@ -399,7 +399,7 @@ static void nvme_uring_cmd_end_io(struct request *req, blk_status_t err)
 }
 
 static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
-		struct io_uring_cmd *ioucmd, unsigned int issue_flags)
+		struct io_uring_cmd *ioucmd, unsigned int issue_flags, bool vec)
 {
 	struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
 	const struct nvme_uring_cmd *cmd = ioucmd->cmd;
@@ -449,7 +449,7 @@ static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 	req = nvme_alloc_user_request(q, &c, nvme_to_user_ptr(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, 0, rq_flags,
+			msecs_to_jiffies(d.timeout_ms) : 0, vec, rq_flags,
 			blk_flags);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
@@ -575,7 +575,10 @@ static int nvme_ns_uring_cmd(struct nvme_ns *ns, struct io_uring_cmd *ioucmd,
 
 	switch (ioucmd->cmd_op) {
 	case NVME_URING_CMD_IO:
-		ret = nvme_uring_cmd_io(ctrl, ns, ioucmd, issue_flags);
+		ret = nvme_uring_cmd_io(ctrl, ns, ioucmd, issue_flags, false);
+		break;
+	case NVME_URING_CMD_IO_VEC:
+		ret = nvme_uring_cmd_io(ctrl, ns, ioucmd, issue_flags, true);
 		break;
 	default:
 		ret = -ENOTTY;

include/uapi/linux/nvme_ioctl.h

@@ -107,5 +107,6 @@ struct nvme_uring_cmd {
 
 /* io_uring async commands: */
 #define NVME_URING_CMD_IO	_IOWR('N', 0x80, struct nvme_uring_cmd)
+#define NVME_URING_CMD_IO_VEC	_IOWR('N', 0x81, struct nvme_uring_cmd)
 
 #endif /* _UAPI_LINUX_NVME_IOCTL_H */