nvme: helper for uring-passthrough checks

Factor out a helper consolidating the error checks, and fix typo in a
comment too. This is in preparation to support admin commands on this
path.
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220520090630.70394-2-joshi.k@samsung.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/host/ioctl.c

@@ -556,22 +556,30 @@ long nvme_ns_chr_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	return __nvme_ioctl(ns, cmd, (void __user *)arg);
 }
 
-static int nvme_ns_uring_cmd(struct nvme_ns *ns, struct io_uring_cmd *ioucmd,
-			     unsigned int issue_flags)
+static int nvme_uring_cmd_checks(unsigned int issue_flags)
 {
-	struct nvme_ctrl *ctrl = ns->ctrl;
-	int ret;
-
-	BUILD_BUG_ON(sizeof(struct nvme_uring_cmd_pdu) > sizeof(ioucmd->pdu));
-
 	/* IOPOLL not supported yet */
 	if (issue_flags & IO_URING_F_IOPOLL)
 		return -EOPNOTSUPP;
 
-	/* NVMe passthrough requires bit SQE/CQE support */
+	/* NVMe passthrough requires big SQE/CQE support */
 	if ((issue_flags & (IO_URING_F_SQE128|IO_URING_F_CQE32)) !=
 	    (IO_URING_F_SQE128|IO_URING_F_CQE32))
 		return -EOPNOTSUPP;
+	return 0;
+}
+
+static int nvme_ns_uring_cmd(struct nvme_ns *ns, struct io_uring_cmd *ioucmd,
+			     unsigned int issue_flags)
+{
+	struct nvme_ctrl *ctrl = ns->ctrl;
+	int ret;
+
+	BUILD_BUG_ON(sizeof(struct nvme_uring_cmd_pdu) > sizeof(ioucmd->pdu));
+
+	ret = nvme_uring_cmd_checks(issue_flags);
+	if (ret)
+		return ret;
 
 	switch (ioucmd->cmd_op) {
 	case NVME_URING_CMD_IO: